Infrared light cut filter, filter for solid-state image sensor, solid-state image sensor, and method for manufacturing a filter for a solid-state image sensor

Abstract

To provide an infrared ray cut filter and the like that can achieve both developability and infrared ray absorptive power.SOLUTION: An infrared ray cut filter 13 includes: a cyanine dye including polymethine, cations located at terminals of polymethine and having heterocycles containing nitrogen, and tris(pentafluoroethyl)trifluorophosphate anions; an acrylic copolymer including a repeating unit represented by the following formula (1) or (2), and having an acid value of 50 KOHmg / g or more and 110 KOHmg / g or less; and a naphthoquinonediazide compound.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to an infrared light cut filter, a filter for a solid-state image sensor, a solid-state image sensor, and a method for manufacturing a filter for a solid-state image sensor. [Background technology]

[0002] Solid-state image sensors, 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 image sensor is capable of detecting light corresponding to multiple colors. The solid-state image sensor includes a color filter for each color and a photoelectric conversion element for each color, and detects light for each color using the photoelectric conversion element for each color (see, for example, Patent Document 1). Another example of a solid-state image sensor includes organic photoelectric conversion elements and inorganic photoelectric conversion elements, and detects light of each color using the photoelectric conversion element without using color filters (see, for example, Patent Document 2).

[0003] A solid-state image sensor is equipped with an infrared light cut-off filter on a photoelectric conversion element. The infrared light absorbing dye in the infrared light cut-off filter absorbs infrared light, thereby cutting off the infrared light that each photoelectric conversion element can detect. This improves the detection accuracy of visible light at each photoelectric conversion element. The infrared light cut-off filter includes, 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 Publication No. 2003-060176 [Patent Document 2] Japanese Patent Publication No. 2018-060910 [Patent Document 3] Japanese Patent Publication No. 2007-219114 [Overview of the project] [Problems that the invention aims to solve]

[0005] Infrared light cut filters in solid-state image sensors may require patterning depending on the layered structure of the image sensor. Methods for patterning thin films such as infrared light cut filters include, for example, photolithography or dry etching. Of these, photolithography does not require processing under vacuum, thus reducing the manufacturing cost of the solid-state image sensor compared to dry etching. Therefore, infrared light cut filters are required to be patternable by photolithography, or in other words, to be developable by photolithography.

[0006] There are two types of transfer methods in photolithography: negative and positive. In the negative method, the exposed portion of the object to be patterned forms the desired pattern. In contrast, in the positive method, the unexposed portion of the object to be patterned forms the desired pattern. In patterning infrared light cut filters, the infrared light cut filter, which is the object to be exposed, contains a cyanine dye. When the cyanine dye contained in the infrared light cut filter is exposed, it may degrade. Therefore, from the viewpoint of suppressing the degradation of the cyanine dye, it is preferable to select the positive method as the transfer method when patterning infrared light cut filters using photolithography.

[0007] On the other hand, positive resists containing naphthoquinone diazide compounds and novolac-type phenolic resins are widely used as resists for forming semiconductor devices. However, when an infrared light cut filter is formed using a positive resist containing a novolac-type phenolic resin, the cyanine dye may remain associated with the filter due to the difference in polarity between the novolac-type phenolic resin and the cyanine dye. This reduces the infrared light absorption capacity of the cyanine dye contained in the infrared light cut filter. [Means for solving the problem]

[0008] An infrared light cut filter for solving the above problems comprises polymethine, a cyanine dye containing a cation having a nitrogen-containing heterocycle located at each end of the polymethine and a tris(pentafluoroethyl)trifluorophosphate anion, an acrylic copolymer having an acid value of 50 KOH mg / g or more and 110 KOH mg / g or less, and a naphthoquinone diazide compound.

[0009] [ka]

[0010] [ka]

[0011] However, in formula (1), R1 is a hydrogen atom or a methyl group, R2 is an organic group having one or more carbon atoms, and R3 is a carboxyl group. Also, in formula (2), R4 is a hydrogen atom or a methyl group.

[0012] A method for manufacturing an infrared light cut filter to solve the above problems includes forming an infrared light cut filter comprising a polymethine, a cyanine dye containing a cation having two nitrogen-containing heterocycles located at each end of the polymethine and a tris(pentafluoroethyl)trifluorophosphate anion, an acrylic copolymer having an acid value of 50 KOH mg / g or more and 110 KOH mg / g or less, and a naphthoquinone diazide compound, and patterning the infrared light cut filter by photolithography.

[0013] According to the above-described infrared light cut filter and method for manufacturing the infrared light cut filter, the acrylic copolymer contains the first repeating unit described above. Since the first repeating unit contains a carboxyl group, the acrylic copolymer containing the first repeating unit can have a carboxyl group in its side chain. This allows the naphthoquinone diazide in the naphthoquinone diazide compound to interact with the carboxyl group of the acrylic copolymer, and as a result, the mixture of the acrylic copolymer and the naphthoquinone diazide compound can be insoluble in alkaline developer. Furthermore, when the naphthoquinone diazide compound is converted to indene carboxylic acid by exposure, the indene carboxylic acid does not interact with the carboxyl group of the acrylic copolymer. This allows the mixture of the acrylic copolymer and the naphthoquinone diazide compound to be soluble in acrylic developer.

[0014] Furthermore, since the acid value of the acrylic copolymer is 50 KOH mg / g or higher, it is possible to enhance the contrast during development in a mixture of the acrylic copolymer and the naphthoquinone diazide compound. In addition, since the acid value of the acrylic copolymer is 110 KOH mg / g or lower, the decrease in the infrared light absorption capacity of the infrared light cut filter can be suppressed.

[0015] According to the infrared light cut filter described above, the aromatic rings contained in the acrylic copolymer are positioned between other cyanine pigments located near the cyanine pigment, making it possible to form a distance between the cyanine pigments sufficient to suppress the aggregation of cyanine pigments. As a result, the decrease in absorbance at wavelengths in which absorption by the cyanine pigment is expected is suppressed.

[0016] In the above infrared light cut filter, the weight of the naphthoquinonediazide compound may be 5% by weight or more and 30% by weight or less based on the weight of the acrylic copolymer. According to this infrared light cut filter, when the amount of the naphthoquinonediazide compound is 5% by weight or more, in the infrared light cut filter, the developability of the unexposed portion is reduced and the developability of the exposed portion is improved. Thereby, the accuracy in the shape of the infrared light cut filter is enhanced. Further, when the amount of the naphthoquinonediazide compound is 30% by weight or less, deterioration of the cyanine dye is suppressed, so that a decrease in the absorbance of the infrared light cut filter is suppressed.

[0017] In the above infrared light cut filter, the average molecular weight of the acrylic copolymer may be 3,000 or more and 150,000 or less. According to this infrared light cut filter, when the average molecular weight of the acrylic copolymer is within this range, it is possible to maintain the developability of the infrared light cut filter while maintaining the spectral characteristics of the cyanine dye contained in the infrared light cut filter.

[0018] A filter for a solid-state imaging device for solving the above problems includes the above infrared light cut filter and a barrier layer that covers the infrared light cut filter and suppresses the transmission of an oxidation source that oxidizes the infrared light cut filter.

[0019] A solid-state imaging device for solving the above problems includes a photoelectric conversion element and the above filter for a solid-state imaging device.

Advantages of the Invention

[0020] According to the present invention, it is possible to achieve both the developability of the infrared light cut filter and the infrared light absorption ability.

Brief Description of the Drawings

[0021] [Figure 1] It is an exploded perspective view showing the structure in a solid-state imaging device of one embodiment.

Mode for Carrying Out the Invention

[0022] Referring to Figure 1, an infrared light cut filter, a filter for a solid-state image sensor, and one embodiment of the solid-state image sensor will be described. Below, the manufacturing method, manufacturing example, and test example of the solid-state image sensor and the filter for the solid-state image sensor will be described in order. In this embodiment, infrared light is light having a wavelength in the range of 0.7 μm to 1 mm, and near-infrared light is light having a wavelength in the range of 700 nm to 1100 nm within the infrared light spectrum.

[0023] [Solid-state image sensor] The solid-state image sensor will be explained with reference to Figure 1. Figure 1 is a schematic diagram showing the individual layers of a part of the solid-state image sensor separated.

[0024] As shown in Figure 1, the solid-state image sensor 10 comprises a solid-state image sensor 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 photoelectric conversion element 11P. Each of the photoelectric conversion elements 11R, 11G, and 11B for each color measures the intensity of visible light having a specific wavelength associated with that photoelectric conversion element 11R, 11G, and 11B. Each infrared photoelectric conversion element 11P measures the intensity of infrared light.

[0025] The solid-state image sensor 10 comprises 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. In Figure 1, for illustrative purposes, the repeating units of the photoelectric conversion elements 11 in the solid-state image sensor 10 are shown.

[0026] The solid-state image sensor filter 10F comprises multiple visible light filters, an infrared light pass filter 12P, an infrared light cut filter 13, multiple visible light microlenses, and an infrared light microlens 15P.

[0027] The visible light color filter consists 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 relative to the red photoelectric conversion element 11R. The green filter 12G is located on the light incident side relative to the green photoelectric conversion element 11G. The blue filter 12B is located on the light incident side relative to the blue photoelectric conversion element 11B.

[0028] The infrared light pass filter 12P is located on the light incident side with respect to the infrared light photoelectric converter 11P. The infrared light pass filter 12P cuts out visible light that the infrared light photoelectric converter 11P can detect. This improves the detection accuracy of infrared light by the infrared light photoelectric converter 11P. The infrared light that the infrared light photoelectric converter 11P can detect is, for example, near-infrared light.

[0029] The infrared light cut filter 13 is located on the light incidence side relative to the respective color filters 12R, 12G, and 12B. The infrared light cut filter 13 has a through hole 13H. When viewed from a viewpoint opposite to the plane on which the infrared light cut filter 13 extends, the infrared light pass filter 12P is located within the region demarcated by the through hole 13H. On the other hand, when viewed from a viewpoint opposite to the plane on which the infrared light cut filter 13 extends, the infrared light cut filter 13 is located on the red filter 12R, the green filter 12G, and the blue filter 12B.

[0030] The infrared light cut filter 13 contains a cyanine dye, which is an infrared light absorbing dye. The cyanine dye has the maximum absorption rate of infrared light at any wavelength included in the near-infrared light spectrum. Therefore, the infrared light cut filter 13 can reliably absorb near-infrared light passing through it. As a result, near-infrared light that can be detected by the photoelectric conversion elements 11 for each color is sufficiently cut off by the infrared light cut filter 13. The infrared light cut filter 13 can have a thickness of, for example, 300 nm or more and 3 μm or less.

[0031] The barrier layer 14 suppresses the transmission of oxidation sources through the infrared light cut filter 13. Oxidation sources include oxygen and water. The oxygen permeability of the barrier layer 14 is, for example, 5.0 cc / m³. 2 It is preferable that the oxygen permeability is less than or equal to / day / atm. The oxygen permeability is a value in accordance with JIS K7126:2006. Oxygen permeability of 5.0 cc / m³ 2 Since the temperature is set to less than / day / atm, the barrier layer 14 prevents oxidation sources from reaching the infrared light cut filter 13, making the infrared light cut filter 13 less susceptible to oxidation by oxidation sources. Therefore, the light resistance of the infrared light cut filter 13 can be improved.

[0032] The material forming the barrier layer 14 is an inorganic compound. Preferably, the material forming the barrier layer 14 is a silicon compound. The material forming the barrier layer 14 may be at least one selected from the group consisting of silicon nitride, silicon oxide, and silicon oxynitride.

[0033] The microlenses consist 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 incident side of the red filter 12R. The green microlens 15G is located on the incident side of the green filter 12G. The blue microlens 15B is located on the incident side of the blue filter 12B. The infrared microlens 15P is located on the incident side of the infrared light pass filter 12P.

[0034] Each microlens 15R, 15G, 15B, and 15P has an incident surface 15S, which is its outer surface. Each microlens 15R, 15G, 15B, and 15P has a refractive index difference between itself and the outside air to focus the light entering the incident surface 15S toward each photoelectric conversion element 11R, 11G, 11B, and 11P. Each microlens 15R, 15G, 15B, and 15P contains a transparent resin.

[0035] [Infrared light cut filter] The infrared light cut filter 13 will be explained in more detail below. The infrared light cut filter 13 contains a cyanine dye, an acrylic copolymer, and a naphthoquinone diazide compound. The cyanine dye contains a cation and anion. The cation is located at the ends of the polymethine and has a nitrogen-containing heterocycle. The anion is the tris(pentafluoroethyl)trifluorophosphate anion.

[0036] The acrylic copolymer contains repeating units represented by the following formula (1) or formula (2), and has an acid value of 50 KOH mg / g or more and 110 KOH mg / g or less.

[0037] [ka]

[0038] [ka]

[0039] However, in formula (1), R1 is a hydrogen atom or a methyl group, R2 is an organic group having one or more carbon atoms, and R3 is a carboxyl group. Also, in formula (2), R4 is a hydrogen atom or a methyl group.

[0040] Positive resists containing a naphthoquinone diazide compound and a novolac-type phenolic resin are widely used as positive resists for forming semiconductor devices. The novolac-type phenolic resin has multiple phenolic hydroxyl groups. The naphthoquinone diazide compound has multiple atomic groups containing naphthoquinone diazide. In an unexposed positive resist, the phenolic hydroxyl groups of the novolac-type phenolic resin interact with the diazonaphthoquinone of the naphthoquinone diazide compound, making the positive resist insoluble in alkaline developer. In contrast, in an exposed positive resist, the naphthoquinone diazide in the naphthoquinone diazide compound changes to indene carboxylic acid, which does not interact with phenolic hydroxyl groups. As a result, the positive resist becomes soluble in alkaline developer.

[0041] When an infrared light cut filter is formed using the positive-type resist described above, the infrared light cut filter exhibits high developability. On the other hand, because the novolac-type phenolic resin contains phenolic hydroxyl groups, the association of cyanine dyes occurs due to the difference in polarity between the phenolic hydroxyl groups and the cyanine dyes. As a result, an infrared light cut filter containing the associated cyanine dyes is formed. The spectral properties of the associated cyanine dyes differ from those of the unassociated cyanine dyes, and consequently, the infrared light absorption capacity of the infrared light cut filter decreases.

[0042] In this regard, the infrared light cut filter of this disclosure contains the first repeating unit described above in the acrylic copolymer. Since the first repeating unit contains a carboxyl group, the acrylic copolymer containing the first repeating unit can have carboxyl groups in its side chains. This allows the naphthoquinone diazide in the naphthoquinone diazide compound to interact with the carboxyl group of the acrylic copolymer, and as a result, the mixture of the acrylic copolymer and the naphthoquinone diazide compound can be insoluble in alkaline developer. Furthermore, when the naphthoquinone diazide compound is converted to indene carboxylic acid by exposure, the indene carboxylic acid does not interact with the carboxyl group of the acrylic copolymer. This allows the mixture of the acrylic copolymer and the naphthoquinone diazide compound to be soluble in acrylic developer.

[0043] The cyanine dye may have the structure shown in formula (3) below.

[0044] [ka]

[0045] In formula (3) above, X is one methine or polymethine. The hydrogen atoms bonded to the carbon atoms in the methine may be substituted with halogen atoms or organic groups. The polymethine may have a cyclic structure containing carbon atoms that form the polymethine. The cyclic structure may include three consecutive carbon atoms in the multiple carbon atoms that form the polymethine. If the polymethine has a cyclic structure, the number of carbon atoms in the polymethine may be five or more. Each nitrogen atom is contained in a five-membered or six-membered heterocycle. The heterocycle may be fused. - It is an anion.

[0046] Furthermore, the cyanine dye may have the structure shown in formula (4) below.

[0047] [ka]

[0048] In formula (4) above, n is an integer of 1 or more. n indicates the number of repeating units contained in the polymethine chain. R11 and R12 are hydrogen atoms or organic groups. R13 and R14 are hydrogen atoms or organic groups. R13 and R14 are preferably linear alkyl groups having 1 or more carbon atoms, or branched alkyl groups. Each nitrogen atom is contained in a five-membered ring or a six-membered ring heterocycle. The heterocycle may be fused.

[0049] In formula (3), if the polymethine includes 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 where the unsaturated bond resonates electronically as part of the polymethine chain. Such cyclic structures 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, and a benzene ring. All of these cyclic structures may have substituents.

[0050] Furthermore, in equation (4), the compound with n = 1 is cyanine, the compound with n = 2 is carbocyanine, and the compound with n = 3 is dicarbocyanine. In equation (4), the compound with n = 4 is tricarbocyanine.

[0051] The organic groups R11 and R12 may be, for example, alkyl groups, aryl groups, aralkyl groups, and alkenyl groups. 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. Aryl groups may be, for example, phenyl groups, tolyl groups, xylyl groups, and naphthyl groups. Aralkyl groups may be, for example, benzyl groups, phenylethyl groups, phenylpropyl groups, and so on. Alkenyl groups may be, for example, vinyl groups, allyl groups, propenyl groups, isopropenyl groups, butenyl groups, hexenyl groups, cyclohexenyl groups, and octenyl groups.

[0052] Furthermore, at least some of the hydrogen atoms in each organic group may be substituted with halogen atoms or cyano groups. Halogen atoms may include fluorine, bromine, and chlorine. Substituted organic groups may include, for example, chloromethyl, chloropropyl, bromoethyl, trifluoropropyl, and cyanoethyl groups.

[0053] R13 or R14 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 heterocycles containing each nitrogen atom may be, for example, pyrrole, imidazole, thiazole, and pyridine. The cations contained in these cyanine dyes may have structures represented by, for example, the following formulas (5) and (6).

[0055] [ka]

[0056] [ka]

[0057] Furthermore, the cations contained in the cyanine dye may have structures shown in formulas (7) to (46) below, for example. That is, each nitrogen atom contained in the cyanine dye may be contained within the cyclic structure shown below.

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[0098] Cyanine dyes have the maximum absorbance of infrared light at any wavelength between 700 nm and 1100 nm. Therefore, the infrared light cut filter 13 can reliably absorb near-infrared light passing through it. As a result, near-infrared light that can be detected by the photoelectric conversion elements 11 for each color is sufficiently cut off by the infrared light cut filter 13.

[0099] The infrared light cut filter 13 may contain only one type of cyanine dye, or it may contain two or more types of cyanine dyes. The absorbance Aλ at wavelength λ is calculated using the following formula. Aλ = -log 10 (%T / 100)

[0100] 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 is transmitted through an infrared light cut filter 13 containing a cyanine dye. In the infrared light cut filter 13, the transmittance T is the intensity of transmitted light when the intensity of incident light is set to 1, and the transmittance percentage %T is obtained by multiplying the transmittance T by 100.

[0101] Tris(pentafluoroethyl)trifluorophosphate anion ([(C2F5)3PF3] - ) has the structure shown by the following formula (47).

[0102] [ka]

[0103] During the manufacturing process of the solid-state image sensor 10, the infrared light cut filter 13 is heated to approximately 200°C. When the cyanine dye is heated to approximately 200°C, the structure of the cyanine dye changes, which can alter the transmittance of the cyanine dye to infrared light.

[0104] In this respect, the FAP anion has a molecular weight and molecular structure that allows it to be located near the polymethine chain in the cyanine dye, thus suppressing the cleavage of the polymethine chain in the cyanine dye by heating. Therefore, the change in the infrared light transmittance of the cyanine dye due to heating is suppressed, and as a result, the change in the infrared light transmittance in the infrared light cut filter 13 is suppressed.

[0105] As described above, the infrared light cut filter 13 contains an acrylic copolymer. The acrylic copolymer may contain repeating units derived from monomers containing acrylic acid or methacrylic acid. A monomer containing acrylic acid is an acrylate, and a monomer containing methacrylic acid is a methacrylate.

[0106] The acrylic copolymer contains a first repeating unit represented by the following formula (1) or formula (2).

[0107] [ka]

[0108] [ka]

[0109] However, in formula (1), R1 is a hydrogen atom or a methyl group, R2 is an organic group having one or more carbon atoms, and R3 is a carboxyl group. Also, in formula (2), R4 is a hydrogen atom or a methyl group. That is, the first repeating unit is derived from a monomer containing a carboxyl group.

[0110] Monomers having a carboxyl group may be, for example, acrylic acid, methacrylic acid, 2-methacryloyloxyethyl succinic acid, 2-acryloyloxyethyl succinic acid, 2-acryloyloxyethyl hexahydrophthalic acid, or 2-acryloyloxyethyl phthalic acid. Acrylic copolymers produced using monomers having a carboxyl group contain a carboxyl group in their side chain.

[0111] The acid value of the acrylic copolymer is within the range of 50 KOH mg / g to 110 KOH mg / g. Preferably, the acid value of the acrylic copolymer is between 80 KOH mg / g and 100 KOH mg / g.

[0112] The acid value of the acrylic copolymer is a value measured by a method conforming to JIS K 0070-1992, "Test methods for acid value, saponification value, ester value, iodine value, hydroxyl value and unsaponifiable matter of chemical products." In this disclosure, the acid value is a value measured by a method conforming to 3.2 "Potential difference measurement method" of the said standard.

[0113] By having the acid value of the acrylic copolymer fall within the above-mentioned range, the developability of the unexposed areas is suppressed, while the developability of the exposed areas is enhanced, thereby further improving the developability of infrared light cut filters containing acrylic copolymers. Specifically, an acid value of 110 KOH mg / g or less suppresses the dissolution of the unexposed areas in the developer. Furthermore, an acid value of 110 KOH mg / g or less suppresses the decrease in the infrared light absorption capacity of the infrared light cut filter. An acid value of 50 KOH mg / g or more increases the dissolution of the exposed areas in the alkaline developer.

[0114] Furthermore, the acid value of an acrylic copolymer has a positive correlation with the number of carboxyl groups it contains. That is, the higher the acid value of the acrylic copolymer, the more carboxyl groups it contains, and the lower the acid value, the fewer carboxyl groups it contains. In this respect, when the acid value of the acrylic copolymer falls within the range described above, the number of carboxyl groups it contains falls within a range that allows for increased solubility in the exposed areas while suppressing an increase in solubility in the unexposed areas.

[0115] Furthermore, by ensuring that the acid value of the acrylic copolymer falls within the aforementioned range, it is possible to reduce the number of first repeating units contained in the acrylic copolymer compared to cases where the acid value of the acrylic copolymer is higher. This allows the acrylic copolymer to contain more repeating units other than the first repeating units.

[0116] Furthermore, the acrylic copolymer may contain monomers other than the acrylic monomers mentioned above. Examples of monomers other than the acrylic monomers mentioned above include styrene monomers, (meth)acrylic monomers, vinyl ester monomers, vinyl ether monomers, halogen-containing vinyl monomers, and diene monomers.

[0117] Examples of styrene monomers include styrene, α-methylstyrene, p-methylstyrene, m-methylstyrene, p-methoxystyrene, p-hydroxystyrene, p-acetoxystyrene, vinyltoluene, ethylstyrene, phenylstyrene, and benzylstyrene.

[0118] (Meth)acrylic monomers include, for example, 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, tetracyclo Dodecyl (meth)acrylate, glycidyl (meth)acrylate, 2-methylglycidyl (meth)acrylate, 2-ethylglycidyl (meth)acrylate, 2-oxyranyl ethyl (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-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 ) may be acrylate, 3-[(3-methyl-3-oxetanyl)methyloxy]propyl (meth)acrylate, 3-[(3-ethyl-3-oxetanyl)methyloxy]propyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, etc.

[0119] Vinyl ester monomers may include, for example, vinyl acetate. Vinyl ether monomers may include, for example, vinyl methyl ether. Halogen-containing vinyl monomers may include, for example, vinyl chloride. Diene monomers may include, for example, butadiene and isobutylene.

[0120] Furthermore, the acrylic copolymer may contain monomers to adjust the polarity of the acrylic copolymer. Monomers for adjusting polarity add acidic or hydroxyl groups to the copolymer. Such monomers may be, for example, acrylic acid, methacrylic acid, maleic anhydride, maleic acid half-ester, 2-hydroxyethyl acrylate, and 4-hydroxyphenyl (meth)acrylic acid.

[0121] Furthermore, the acrylic copolymer may have any of the following structures: random copolymer, alternating copolymer, block copolymer, or graft copolymer. If the copolymer structure is random copolymer, the manufacturing process and preparation with cyanine dye are easy. For this reason, random copolymer is preferred over other copolymers.

[0122] Polymerization methods for obtaining acrylic copolymers may include, for example, radical polymerization, cationic polymerization, anionic polymerization, living radical polymerization, living cationic polymerization, and living anionic polymerization. Radical polymerization is preferred as the polymerization method for obtaining acrylic copolymers because it is easily industrially produced. Radical polymerization may include solution polymerization, emulsion polymerization, bulk polymerization, and suspension polymerization. Solution polymerization is preferred for radical polymerization. Using solution polymerization makes it easy to control the average molecular weight in the acrylic copolymer. Furthermore, after monomer polymerization, the solution containing the copolymer can be used in the state of the solution for manufacturing filters for solid-state image sensors.

[0123] In radical polymerization, the monomers described above may be diluted with a polymerization solvent, and then a radical polymerization initiator may be added to carry out the polymerization of the monomers. The polymerization solvent may be, for example, an ester solvent, an alcohol ether solvent, a ketone solvent, an aromatic solvent, an amide solvent, or an alcohol solvent. Ester solvents may be, for example, methyl acetate, ethyl acetate, n-butyl acetate, isobutyl acetate, t-butyl acetate, methyl lactate, ethyl lactate, and propylene glycol monomethyl ether acetate. Alcohol ether solvents may be, for example, 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. Ketone solvents may be, for example, acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Aromatic solvents may be, for example, benzene, toluene, and xylene. Amide solvents may be, for example, formamide and dimethylformamide. Alcohol-based solvents may include, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, s-butanol, t-butanol, diacetone alcohol, and 2-methyl-2-butanol. Of these, ketone-based solvents and ester-based solvents are preferred because they can be used in the manufacture of filters for solid-state image sensors. In addition, one of the polymerization solvents described above may be used alone, or two or more may be used in mixture form.

[0124] In radical polymerization, the amount of polymerization solvent used is not particularly limited, but 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 1000 parts by weight or less, and more preferably 10 parts by weight or more and 500 parts by weight or less.

[0125] The radical polymerization initiator may be, for example, a peroxide and an azo compound. The peroxide may be, for example, benzoyl peroxide, t-butyl peroxyacetate, t-butyl peroxybenzoate, and di-t-butyl peroxide. The azo compound may be, for example, azobisisobutyronitrile, azobisamidinopropane salt, azobiscyanovaleric acid (salt), and 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide].

[0126] The amount of radical polymerization initiator used is preferably 0.0001 parts by weight or more and 20 parts by weight or less, more preferably 0.001 parts by weight or more and 15 parts by weight or less, and even more preferably 0.005 parts by weight or more and 10 parts by weight or less, 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 polymerization begins, or it may be added dropwise into the polymerization reaction system. Adding the radical polymerization initiator dropwise to the monomers and polymerization solvent into the polymerization reaction system is preferable because it can suppress the exothermic reaction caused by polymerization.

[0127] The reaction temperature for radical polymerization is appropriately selected depending on the type of radical polymerization initiator and polymerization solvent. From the viewpoint of ease of manufacture and reaction controllability, the reaction temperature is preferably between 60°C and 110°C.

[0128] The glass transition temperature of the acrylic 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 increase the certainty of suppressing changes in the transmittance of infrared light when the infrared light cut filter 13 is heated in the infrared light cut filter.

[0129] The average molecular weight of the acrylic copolymer is preferably between 3,000 and 150,000, and more preferably between 5,000 and 50,000. By having the average molecular weight of the acrylic copolymer fall within this range, it is possible to maintain the developability of the infrared light cut filter 13 while preserving the spectral characteristics of the cyanine dye contained in the infrared light cut filter 13.

[0130] When an acrylic copolymer has an average molecular weight exceeding 150,000, its solubility in the developer decreases. As a result, when an infrared light cut filter 13 containing an acrylic copolymer is developed, the infrared light cut filter 13 becomes less soluble in the developer, making it easier for the infrared light cut filter 13 to peel off from its support. Therefore, when the average molecular weight of the acrylic copolymer exceeds 150,000, it is not easy to pattern the infrared light cut filter 13. In contrast, if the average molecular weight of the acrylic copolymer is 150,000 or less, the solubility of the acrylic copolymer in the developer does not decrease significantly, thus suppressing the peeling of the infrared light cut filter 13 during development. Therefore, it is easier to pattern the infrared light cut filter 13.

[0131] Furthermore, if the average molecular weight of the acrylic copolymer is less than 3000, it is difficult to suppress the association of cyanine pigments contained in the infrared light cut filter 13. As a result, the absorbance in the infrared region of the infrared light cut filter 13 tends to decrease. On the other hand, if the average molecular weight of the acrylic copolymer is 3000 or more, the acrylic copolymer suppresses the association of cyanine pigments contained in the infrared light cut filter 13. This suppresses the decrease in absorbance in the infrared region of the infrared light cut filter 13.

[0132] The average molecular weight of an acrylic copolymer is its weight-average molecular weight. This weight-average molecular weight can be measured, for example, by gel permeation chromatography. For instance, in a radical polymerization reaction, the average molecular weight of an acrylic copolymer can be controlled by changing the concentrations of monomers and radical polymerization initiators in the solution.

[0133] The polymer solution obtained by the production of the acrylic copolymer contains the acrylic copolymer and the acrylic monomer. The acrylic monomer is the monomer that was prepared for the production of the acrylic copolymer but was not used in the production of the acrylic copolymer. In the polymer solution, the weight of the acrylic copolymer is the first weight W1, and the weight of the acrylic monomer is the second weight W2.

[0134] The percentage of the second weight W2 ({W2 / (W1+W2)}×100) relative to the sum of the first weight W1 and the second weight W2 (W1+W2) is preferably 20% or less. In other words, it is preferable that the residual monomer of the monomer prepared for the production of the acrylic copolymer is 20% or less. By having a residual monomer of 20% or less, the improvement in transmittance in the infrared light cut filter is suppressed compared to when the residual monomer is greater than 20%.

[0135] Furthermore, the percentage of the second weight W2 to the sum of the first weight W1 and the second weight W2 is more preferably 10% or less, and even more preferably 3% or less. The first weight W1 and the second weight W2 can be quantified based on the analysis results of the acrylic copolymer. The analysis method for the acrylic copolymer may be, for example, gas chromatography-mass spectroscopy (GC-MS), nuclear magnetic resonance spectroscopy (NMR), and infrared spectroscopy (IR).

[0136] For example, when quantifying the first weight W1 and the second weight using NMR analysis results, first, a spectrum for the polymer solution is obtained by NMR analysis. Next, the peaks for the acrylic copolymer and the peaks for the acrylic monomer are identified in the obtained spectrum. Then, the area ratio of each peak is calculated. The area ratio of the acrylic copolymer peak is the first weight W1, and the area ratio of the acrylic monomer peak is the second weight W2.

[0137] Methods for changing the percentage of the second weight W2 relative to the sum of the first weight W1 and the second weight W2 may include, for example, changing the polymerization time and changing the polymerization temperature. Alternatively, a method for changing the percentage of the second weight W2 relative to the sum of the first weight W1 and the second weight W2 may be changing the concentrations of the monomer and radical polymerization initiator at the start of the polymerization reaction. Another method for changing the percentage of the second weight W2 relative to the sum of the first weight W1 and the second weight W2 may be changing the purification conditions after the polymerization reaction. Of these, changing the polymerization time is preferred because it provides high precision in controlling the proportion of the second weight W2.

[0138] When the radical polymerization initiator used during the polymerization of the acrylic copolymer is an organic peroxide having an aromatic ring in its side chain, it is preferable that the infrared light cut filter contains less than 0.35 parts by weight of organic peroxide when the copolymer contained in the infrared light cut filter is set to 100 parts by weight. By containing less than 0.35 parts by weight of organic peroxide in the infrared light cut filter, the degradation of the spectral characteristics of the infrared light cut filter in the visible light region and the infrared light region is suppressed.

[0139] The naphthoquinone diazide compound may be a naphthoquinone diazide-based photosensitive agent. Naphthoquinone diazide-based photosensitive agents are also used as photosensitive agents for positive-type photoresists. The naphthoquinone diazide-based photosensitive agent may be, for example, an ester compound of naphthoquinone diazidosulfonic acid chloride and a phenolic compound.

[0140] The naphthoquinone diazide sulfonate chloride may be, for example, 1,2-naphthoquinone-2-diazide-5-sulfonate chloride or 1,2-naphthoquinone-2-diazide-4-sulfonate chloride.

[0141] Phenolic compounds include, for example, trihydroxybenzophenone, tetrahydroxybenzophenone, pentahydroxybenzophenone, hexahydroxybenzophenone, (polyhydroxyphenyl)alkanes, 2,3,4-trihydroxybenzophenone, 2,4,6-trihydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,3,4,3'-tetrahydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, and 2,3,4,2'-tetrahydroxy-4'-methylbenzophenone. phenone, 2,3,4,4'-tetrahydroxy-3'-methoxybenzophenone, 2,3,4,2',6'-pentahydroxybenzophenone, 2,4,6,3',4',5'-hexahydroxybenzophenone, 3,4,5,3',4',5'-hexahydroxybenzophenone, bis(2,4-dihydroxyphenyl)methane, bis(p-hydroxyphenyl)methane, tris(p-hydroxyphenyl)methane, 1,1,1-tris(p-hydroxyphenyl)ethane, bis(2,3,4-trihydroxyphenyl)methane, 2,2 -Bis(2,3,4-trihydroxyphenyl)propane, 1,1,3-tris(2,5-dimethyl-4-hydroxyphenyl)-3-phenylpropane, 4,4'-[1-{4-(1-[4-hydroxyphenyl]-1-methylethyl)phenyl}ethylidene]bisphenol, bis(2,5-dimethyl-4-hydroxyphenyl)-2-hydroxyphenylmethane, 3,3,3',3'-tetramethyl-1,1'-spirovindene-5,6,7,5',6',7'-hexanol, 2,2,4-trimethyl-7,2',4'-trimethyl The compounds may be droxyflavan, 2-methyl-2-(2,4-dihydroxyphenyl)-4-(4-hydroxyphenyl)-7-hydroxychroman, 1-[1-{3-(1-[4-hydroxyphenyl]-1-methylethyl)-4,6-dihydroxyphenyl}-1-methylethyl]-3-[1-{3-(1-[4-hydroxyphenyl]-1-methylethyl)-4,6-dihydroxyphenyl}-1-methylethyl]benzene, or 4,6-bis{1-(4-hydroxyphenyl)-1-methylethyl}-1,3-dihydroxybenzene. The infrared light cut filter 13 may contain only one naphthoquinone diazide compound, or it may contain two or more.

[0142] The weight of the naphthoquinone diazide compound may be between 5% and 30% by weight relative to the weight of the acrylic copolymer. That is, when the total amount of the acrylic copolymer is set to 100% by weight, the weight of the naphthoquinone diazide compound may be between 5% and 30% by weight relative to the total amount of the acrylic copolymer.

[0143] When the amount of naphthoquinone diazide compound is 5% by weight or more, the developability of the unexposed areas of the infrared light cut filter 13 decreases, while the developability of the exposed areas improves. This improves the precision of the shape of the infrared light cut filter 13. Furthermore, when the amount of naphthoquinone diazide compound is 30% by weight or less, the degradation of the cyanine dye is suppressed, thus suppressing the decrease in absorbance of the infrared light cut filter 13.

[0144] The infrared light cut filter 13 may contain surfactants, preservatives, adhesives, heat-resistant enhancers, etc. The infrared light cut filter 13 may contain only one of these, or two or more.

[0145] [Manufacturing method for filters for solid-state image sensors] The method for manufacturing the filter 10F for a solid-state image sensor includes forming an infrared light cut filter 13 and patterning the infrared light cut filter 13 by photolithography. The formation of the infrared light cut filter 13 involves forming an infrared light cut filter 13 containing a cyanine dye, an acrylic copolymer, and a naphthoquinone diazide compound. The acrylic copolymer contains a first repeating unit represented by formula (1) or formula (2) described above. The method for manufacturing the filter 10F for a solid-state image sensor will be described in more detail below.

[0146] The filters 12R, 12G, 12B for each color, and the infrared light pass filter 12P are formed by forming a coating film containing a colored photosensitive resin and patterning the coating film using photolithography. For example, the coating film containing the red photosensitive resin is formed by applying a coating solution containing the red photosensitive resin and drying the coating film formed by the application. The red filter 12R is formed by exposing the coating film containing the red photosensitive resin to the area corresponding to the red filter 12R and then developing it. The green filter 12G, the blue filter 12B, and the infrared light pass filter 12P are formed in the same way as the red filter 12R.

[0147] 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 used individually or in combination of two or more types. The pigments are preferably highly color-developing and highly heat-resistant, particularly highly heat-degradable, and are preferably organic pigments. Examples of organic pigments include phthalocyanine-based, azo-based, anthraquinone-based, quinacridone-based, dioxazine-based, anthensrone-based, indanthrone-based, perylene-based, thioindigo-based, isoindoline-based, quinophthalone-based, and diketopyrrolopyrrole-based pigments.

[0148] Furthermore, the coloring component contained in the infrared light pass filter 12P may be a black pigment or a black dye. The black pigment may be a single pigment that is black, or a mixture of two or more pigments that is black. Examples of black dyes may be azo dyes, anthraquinone dyes, azine dyes, quinoline dyes, perinone dyes, perylene dyes, and methine dyes.

[0149] Each color of photosensitive coloring composition further includes a binder resin, a photopolymerization initiator, a polymerizable monomer, an organic solvent, and a leveling agent. When forming the infrared light cut filter 13, a coating solution containing the cyanine dye, acrylic copolymer, naphthoquinone diazide compound, and organic solvent is applied to the respective color filters 12R, 12G, 12B and the infrared light pass filter 12P. This forms the infrared light cut filter 13. Next, the infrared light cut filter 13 is exposed using a positive-type photomask. After that, the exposed infrared light cut filter 13 is developed using an alkaline developer, then the developed infrared light cut filter 13 is washed with water and dried. The dried infrared light cut filter 13 is cured by heating. This patterns the infrared light cut filter 13.

[0150] An aqueous solution of tetraammonium hydroxide (TMAH) can be used as the alkaline developer. The concentration of the TMAH aqueous solution is not particularly limited, as long as it is at a concentration that allows for the development of the infrared light cut filter 13. The method of bringing the infrared light cut filter 13 into contact with the developer may be the dip method, the spray method, or the spin method.

[0151] The barrier layer 14 is formed by a vapor deposition method such as sputtering, CVD, or ion plating, or by a liquid deposition method such as coating. The barrier layer 14 formed from silicon oxide can be formed, for example, by sputtering on a substrate on which the infrared light cut filter 13 is formed using a silicon oxide target. The barrier layer 14 formed from silicon oxide can be formed, for example, by CVD using silane and oxygen on a substrate on which the infrared light cut filter 13 is formed. The barrier layer 14 formed from silicon oxide can be formed, for example, by coating, modifying, and drying a coating solution containing polysilazane. The layer structure of the barrier layer 14 may be a single layer structure made of a single compound, a stacked structure of layers made of a single compound, or a stacked structure of layers made of mutually different compounds.

[0152] 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 reflow by heat treatment. The transparent resin is, 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, a norbornene resin, or the like.

[0153] [Production Example] Referring to Table 1, a production example in an acrylic polymer for manufacturing an infrared cut filter will be described. When the acrylic polymer is a copolymer produced using two or more monomers, the weight ratio in the repeating units derived from each monomer in the produced copolymer is equal to the weight ratio of each monomer at the time of copolymer production.

[0154] In Table 1, IBXMA is isobornyl methacrylate (C 14 H 22 O2), BzMA is benzyl methacrylate (C 11 H 12 O2), and HPMA is 4-hydroxyphenyl methacrylate (C 10 H 10 O3). Also, AA is acrylic acid (C3H4O2), and MAA is methacrylic acid (C4H6O2). Among these, acrylic acid and methacrylic acid are acrylic monomers containing a carboxyl group.

[0155]

Table 1

[0156] [Production Example 1] 150 parts by weight of propylene glycol monomethyl ether acetate (PGMAc) was prepared as the polymerization solvent. Additionally, 15 parts by weight of isobonyl methacrylate, 69 parts by weight of benzyl methacrylate, and 16 parts by weight of acrylic acid were prepared as acrylic monomers. Furthermore, 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 tubing, and the mixture was stirred and refluxed for 8 hours while heating to 80°C, with nitrogen gas being introduced into the vessel. This yielded a polymer solution containing an acrylic copolymer produced from isobonyl methacrylate, benzyl methacrylate, and acrylic acid.

[0157] [Manufacturing Example 2] 15 parts by weight of isobonyl methacrylate, 72 parts by weight of benzyl methacrylate, and 13 parts by weight of acrylic acid were prepared as acrylic monomers. Otherwise, a polymer solution containing an acrylic copolymer produced from isobonyl methacrylate, benzyl methacrylate, and acrylic acid was obtained by the same method as in Production Example 1.

[0158] [Manufacturing Example 3] 15 parts by weight of isovonyl methacrylate, 75 parts by weight of benzyl methacrylate, and 10 parts by weight of acrylic acid were prepared as acrylic monomers. Otherwise, a polymer solution containing an acrylic copolymer produced from isovonyl methacrylate, benzyl methacrylate, and acrylic acid was obtained by the same method as in Production Example 1.

[0159] [Manufacturing Example 4] Fifteen parts by weight of isovonyl methacrylate, 79 parts by weight of benzyl methacrylate, and 6 parts by weight of acrylic acid were prepared as acrylic monomers. Otherwise, a polymer solution containing an acrylic copolymer produced from isovonyl methacrylate, benzyl methacrylate, and acrylic acid was obtained by the same method as in Production Example 1.

[0160] [Manufacturing Example 5] 15 parts by weight of isobonyl methacrylate, 70 parts by weight of benzyl methacrylate, and 15 parts by weight of methacrylic acid were prepared as acrylic monomers. Otherwise, a polymer solution containing an acrylic copolymer produced from isobonyl methacrylate, benzyl methacrylate, and methacrylic acid was obtained by the same method as in Production Example 1.

[0161] [Manufacturing Example 6] 15 parts by weight of isobonyl methacrylate, 73 parts by weight of benzyl methacrylate, and 12 parts by weight of methacrylic acid were prepared as acrylic monomers. Otherwise, a polymer solution containing an acrylic copolymer produced from isobonyl methacrylate, benzyl methacrylate, and methacrylic acid was obtained by the same method as in Production Example 1.

[0162] [Manufacturing Example 7] Fifteen parts by weight of isobonyl methacrylate, eighty parts by weight of benzyl methacrylate, and five parts by weight of methacrylic acid were prepared as acrylic monomers. Otherwise, a polymer solution containing an acrylic copolymer produced from isobonyl methacrylate, benzyl methacrylate, and methacrylic acid was obtained by the same method as in Production Example 1.

[0163] [Manufacturing Example 8] 100 parts by weight of 4-hydroxyphenyl methacrylate was prepared as the acrylic monomer. Otherwise, a polymer solution containing an acrylic homopolymer produced from 4-hydroxyphenyl methacrylate was obtained by the same method as in Production Example 1.

[0164] [Manufacturing Example 9] 70 parts by weight of benzyl methacrylate and 30 parts by weight of 4-hydroxyphenyl methacrylate were prepared as acrylic monomers. Otherwise, a polymer solution containing an acrylic copolymer produced from benzyl methacrylate and 4-hydroxyphenyl methacrylate was obtained by the same method as in Production Example 1.

[0165] [Method for measuring acid value] The acid value of the acrylic copolymers in each manufacturing example was measured using the following method. As mentioned above, the acid value was measured using the method compliant with JIS K 0070-1992 "Test methods for acid value, saponification value, ester value, iodine value, hydroxyl value and unsaponifiable matter of chemical products," section 3.2 "Potential difference measurement method."

[0166] In detail, 1.5 g of polymer solution was dissolved in a mixed solvent of 90 g of acetone and 10 g of water, and the mixed solvent containing the polymer was titrated with a 0.1 mol / L potassium hydroxide ethanol solution. An automatic titrator (COM-A19, manufactured by Hiranuma Sangyo Co., Ltd.) was used for the titration. The weight of the non-volatile components in the polymer solution was then calculated by removing the volatile components from the polymer solution. Next, the concentration of the non-volatile components was determined by dividing the weight of the non-volatile components by the weight of the polymer solution, and then the acid value per gram of polymer was determined using this concentration (mgKOH / g).

[0167] [Test Example 1] In each manufacturing example, a 25% polymer solution was obtained by diluting the polymer solution so that the weight of the homopolymer or acrylic copolymer relative to the weight of the polymer solution was 25%. The infrared light cut filters of Test Examples 1-1 to 1-9 were obtained by sequentially using the 25% polymer solutions from Manufacturing Examples 1 to 9. The infrared light cut filters in each test example before exposure were prepared by the following method.

[0168] A coating solution was prepared containing 0.4 g of cyanine dye, 12.5 g of a 25% polymer solution, 0.625 g of a naphthoquinone diazide compound, and 10 g of propylene glycol monomethyl ether acetate. In this preparation, the cyanine dye used was the dye represented by formula (5) above, and nine polymer solutions containing the acrylic copolymers obtained in Production Examples 1 to 9 described above were used. Furthermore, as the naphthoquinone diazide compound, an ester of 4,4'-[1-[4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl]ethylidene]bisphenol and 1,2-naphthoquinone-2-diazide-5-sulfonic acid chloride was used. A coating film was formed by applying the coating solution to a transparent substrate, and then the film was heated to 90°C. This dried the film, resulting in a pre-exposure infrared light cut filter with a thickness of 2.0 μm.

[0169] Furthermore, using a novolac-based positive resist (OFPR-800, manufactured by Tokyo Ohka Kogyo Co., Ltd.), infrared light cut filters for Test Examples 1-10 were obtained by the following method. Positive resist was diluted with propylene glycol monomethyl ether acetate to a solid content of 25% by weight. Next, 0.4 g of cyanine dye was mixed with the diluted positive resist to prepare a coating solution. In this case, the dye represented by formula (5) above was used as the cyanine dye. A coating film was formed by applying the coating solution onto a transparent substrate, and then the coating film was heated to 90°C. By drying the coating film in this way, infrared light cut filters of Test Examples 1-10 with a thickness of 2.0 μm were obtained.

[0170] [Evaluation of developability] The development rate (R1) of the infrared light cut filter in the exposed area and the development rate (R2) of the infrared light cut filter in the unexposed area were calculated using the method described below. The ratio of the development rate R1 in the exposed area to the development rate R2 in the unexposed area (R1 / R2) was calculated as the development contrast.

[0171] [Development speed R1 in the exposure area] An unexposed infrared cut filter was exposed using an exposure unit (FPA-5510iZ, manufactured by Canon Inc.). The exposure setting of the exposure unit was 5000 J / m². 2 The settings were adjusted as follows. Next, the concentration of tetraammonium hydroxide (TMAH) was adjusted with pure water to 0.05% by weight, thereby producing an alkaline developer. After exposure, the infrared cut filter was immersed in the alkaline developer for 10 seconds, and then washed with pure water for 30 seconds. Subsequently, the thickness of the infrared cut filter after immersion in the alkaline developer was measured. Based on the change in the thickness of the infrared cut filter before and after immersion in the alkaline developer, and the immersion time of the infrared cut filter in the alkaline developer, the development speed R1 (nm / s) of the exposed area was calculated using the following formula. Development speed R1 (nm / s) = change in thickness / immersion time

[0172] In the formula for calculating the development speed R1, the change in thickness was calculated by subtracting the thickness of the infrared light cut filter after immersion in the alkaline developer from the thickness of the infrared light cut filter before immersion in the alkaline developer. As mentioned above, the thickness of the infrared light cut filter before immersion in the alkaline developer was 2.0 μm. Also, as mentioned above, the immersion time was set to 10 seconds.

[0173] Furthermore, the development speed R1 was calculated using an alkaline developer obtained by adjusting the TMAH concentration with pure water to 2.4% by weight, in the same manner as when using a 0.05% by weight alkaline developer.

[0174] [Development speed R2 in unexposed areas] An alkaline developer was prepared by adjusting the TMAH concentration to 0.05% by weight using pure water. An unexposed infrared cut filter was then immersed in the alkaline developer for 30 seconds, and subsequently washed with pure water for 10 seconds. The thickness of the infrared cut filter after immersion in the alkaline developer was then measured. Based on the change in the thickness of the infrared cut filter before and after immersion in the alkaline developer, and the immersion time of the infrared cut filter in the alkaline developer, the development rate R2 (nm / s) of the unexposed area was calculated using the following formula.

[0175] Development speed R2 (nm / s) = change in thickness / immersion time In the formula for calculating the development speed R2, the change in thickness was calculated by subtracting the thickness of the infrared light cut filter after immersion in the alkaline developer from the thickness of the infrared light cut filter before immersion in the alkaline developer. As mentioned above, the thickness of the infrared light cut filter before immersion in the alkaline developer was 2.0 μm. Also, as mentioned above, the immersion time was set to 10 seconds.

[0176] Furthermore, the development speed R2 was calculated using an alkaline developer obtained by adjusting the TMAH concentration with pure water to 2.4% by weight, in the same manner as when using a 0.05% by weight alkaline developer.

[0177] [Ratio of development speed R1 to development speed R2] The development contrast was calculated as the ratio of the development speed R1 in the exposed area to the development speed R2 in the unexposed area using the following formula. The development contrast was calculated for both cases: when the TMAH concentration was 0.05 wt% and when it was 2.4 wt%.

[0178] Development contrast = Development speed R1 in exposed areas / Development speed R2 in unexposed areas Furthermore, if the development contrast of an infrared light cut filter is 10 or higher, the accuracy of pattern formation in the infrared light cut filter is good. In other words, the infrared light cut filter has high development performance.

[0179] [Spectroscopic properties] An unexposed infrared cut filter was cured by heating it to 200°C. The transmittance of the cured infrared cut filter for light with wavelengths from 350 nm to 1150 nm was measured using a spectrophotometer (U-4100, Hitachi High-Technologies Corporation). This obtained the transmittance spectrum for each infrared cut filter. The transmittance spectrum for the cyanine dye represented by equation (5) above shows the lowest transmittance at 950 nm. An infrared cut filter with a transmittance of 20% or less at 950 nm has desirable infrared light absorption when applied to a solid-state image sensor.

[0180] [Evaluation Results] For each test example of the infrared light cut filter, the evaluation results for development speed R1, development speed R2, development contrast, and spectral characteristics are shown in Table 2 below.

[0181] [Table 2]

[0182] As shown in Table 2, the infrared light cut filters in Test Examples 1-1 to 1-7 showed a development contrast of 4 or higher when the TMAH concentration was either 0.05% by weight or 2.4% by weight. In addition, the infrared light cut filters in Test Examples 1-1 to 1-7 showed a transmittance of 40% or less for light with a wavelength of 950 nm.

[0183] In contrast, compared to the infrared light cut filters of Test Examples 1-1 to 1-7, the infrared light cut filter of Test Example 1-8 showed higher development contrast while also exhibiting higher transmittance of light with a wavelength of 950 nm. Furthermore, the infrared light cut filter of Test Example 1-9 showed similar transmittance of light with a wavelength of 950 nm, but with lower development contrast. Finally, the infrared light cut filter of Test Example 1-10 showed high development contrast while also exhibiting high transmittance of light with a wavelength of 950 nm.

[0184] Thus, it was found that the acrylic copolymer contained in the infrared light cut filter, by containing a first repeating unit derived from a monomer containing a carboxyl group, prevents either the development contrast or the transmittance from becoming extremely low compared to cases where the first repeating unit is not present. In other words, by including the first repeating unit in the acrylic copolymer, it can be said that the infrared light cut filter achieves both low transmittance to infrared light and good developability.

[0185] In particular, in test examples 1-2, 1-3, 1-5, and 1-6, it was observed that the development contrast was 10 or higher, and the transmittance of light with a wavelength of 950 nm was 20% or less. From these results, it can be said that when the acid value of the acrylic copolymer is within the range of 50 KOH mg / g to 110 KOH mg / g, and especially within the range of 80 KOH mg / g to 100 KOH mg / g, both lower transmittance to infrared light and higher developability can be achieved.

[0186] [Test Example 2] [Content of naphthoquinone diazide compounds] By using the acrylic copolymer from Manufacturing Example 2, seven types of infrared light cut filters, as described below, were obtained.

[0187] A coating solution was prepared containing 0.4 g of cyanine dye, 12.5 g of a 25% polymer solution, a naphthoquinone diazide compound, and 10 g of propylene glycol monomethyl ether acetate. The cyanine dye used was the one represented by formula (5) above. The naphthoquinone diazide used was an ester of 4,4'-[1-[4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl]ethylidene]bisphenol and 1,2-naphthoquinone-2-diazide-5-sulfonic acid chloride. The coating solution was applied to a transparent substrate to form a coating film, which was then heated to 90°C. This dried the coating film, resulting in an infrared light cut filter with a thickness of 2.0 μm.

[0188] By changing the amount of naphthoquinone diazide compound in seven different ways, as shown in Table 3 below, seven types of infrared light cut-off filters were obtained.

[0189] [Table 3]

[0190] As shown in Table 3, in Test Example 2-1, the amount of naphthoquinone diazide compound was set to 0.095 g, which resulted in the amount of naphthoquinone diazide compound being 3% by weight when the acrylic copolymer was 100% by weight. In Test Example 2-2, the amount of naphthoquinone diazide compound was set to 0.155 g, which resulted in the amount of naphthoquinone diazide compound being 5% by weight when the acrylic copolymer was 100% by weight.

[0191] In Test Example 2-3, the amount of naphthoquinone diazide compound was set to 0.315 g, which resulted in the amount of naphthoquinone diazide compound being 10% by weight when the acrylic copolymer was 100% by weight. In Test Example 2-4, the amount of naphthoquinone diazide compound was set to 0.625 g, which resulted in the amount of naphthoquinone diazide compound being 20% ​​by weight when the acrylic copolymer was 100% by weight.

[0192] In Test Example 2-5, the amount of naphthoquinone diazide compound was set to 0.950 g, which resulted in the amount of naphthoquinone diazide compound being 30% by weight when the acrylic copolymer was 100% by weight. In Test Example 2-6, the amount of naphthoquinone diazide compound was set to 1.100 g, which resulted in the amount of naphthoquinone diazide compound being 35% by weight when the acrylic copolymer was 100% by weight. In Test Example 2-7, the amount of naphthoquinone diazide compound was set to 1.250 g, which resulted in the amount of naphthoquinone diazide compound being 40% by weight when the acrylic copolymer was 100% by weight.

[0193] [Evaluation Results] Using the same method as described in Test Example 1, the development speed R1 in the exposed area, the development speed R2 in the unexposed area, and the development contrast were calculated for each infrared light cut filter in each test example. For the evaluation of developability, the TMAH concentration was set to 2.4% by weight. Furthermore, the spectral characteristics of each infrared light cut filter in each test example were measured using the same method as described in Test Example 1. The results of the evaluation of development speed R1, development speed R2, development contrast, and spectral characteristics are shown in Table 4 below.

[0194] [Table 4]

[0195] As shown in Table 4, the infrared light cut filters of Test Examples 2-1 to 2-7 were found to suppress the extreme decrease in either the development contrast or the spectral characteristics of the acrylic polymer compared to the case where the first repeating unit was not present. In other words, the infrared light cut filters of Test Examples 2-1 to 2-7 were found to achieve a balance between developability and infrared light absorption. In particular, in Test Example 2-1, even with a small amount of naphthoquinone diazide compound, the development contrast was found to be higher than in Test Example 1-9, which is a test example containing an acrylic polymer without the first repeating unit.

[0196] Furthermore, according to the infrared light cut filters in Test Examples 2-2 to 2-7, specifically, when the acrylic copolymer is 100% by weight, it was found that the development contrast in the infrared light cut filters was further enhanced when the amount of naphthoquinone diazide compound was 5% by weight or more. In detail, it was found that the infrared light cut filters exhibited a development contrast of 10 or higher.

[0197] On the other hand, according to the infrared light cut filters of Test Examples 2-1 to 2-5, that is, when the acrylic copolymer is 100% by weight, it was found that the infrared light absorption capacity of the infrared light cut filter was further enhanced when the amount of naphthoquinone diazide compound was 30% by mass or less. Specifically, it was found that the transmittance of light with a wavelength of 950 nm was 20% or less in the infrared light cut filter.

[0198] Thus, from the viewpoint of achieving both the developability and infrared light absorption capacity of the infrared light cut filter, it was found that when the acrylic copolymer is 100% by weight, the amount of the naphthoquinone diazide compound is preferably 5% to 30% by weight.

[0199] As described above, according to one embodiment of an infrared light cut filter, a filter for a solid-state image sensor, a solid-state image sensor, and a method for manufacturing a filter for a solid-state image sensor, the effects described below can be obtained.

[0200] (1) According to the acrylic copolymer containing the first repeating unit, it is possible to increase the ratio of the development rate when insoluble in an alkaline developer to the development rate when soluble in an alkaline developer.

[0201] (2) When the acid value of the acrylic copolymer is within the range of 50 KOH mg / g or more and 110 KOH mg / g or less, the developability of the unexposed portion is suppressed, and the developability of the exposed portion is enhanced. As a result, it is possible to further enhance the developability of the infrared cut filter containing the acrylic copolymer. Further, when the acid value of the acrylic copolymer is 110 KOH mg / g or less, it is possible to suppress a decrease in the infrared light absorption ability in the infrared cut filter.

[0202] (3) If the molecular weight of the acrylic copolymer is 150,000 or less, the solubility of the acrylic copolymer in the developer is less likely to decrease, so peeling of the infrared cut filter 13 during development of the infrared cut filter 13 is suppressed. Therefore, patterning of the infrared cut filter 13 is easy.

[0203] (4) When the molecular weight of the acrylic copolymer is 3,000 or more, the association of the cyanine dye contained in the infrared cut filter 13 is suppressed by the acrylic copolymer. Thereby, a decrease in the absorbance in the infrared region in the infrared cut filter 13 is suppressed.

[0204] (5) When the amount of the naphthoquinone diazide compound is 5% by weight or more, in the infrared cut filter 13, the developability of the unexposed portion decreases, and the developability of the exposed portion improves. As a result, the accuracy of the shape of the infrared cut filter 13 is enhanced. Further, when the amount of the naphthoquinone diazide compound is 30% by weight or less, deterioration of the cyanine dye is suppressed, so a decrease in the absorbance of the infrared cut filter 13 is suppressed.

[0205] The above-described embodiment can be implemented with the following modifications. [Barrier layer] The barrier layer 14 is not limited to being placed between the infrared light cut filter 13 and the microlenses 15R, 15G, 15B, and 15P, but may also be placed on the outer surface of each microlens 15R, 15G, 15B, and 15P.

[0206] The solid-state image sensor 10 may have an anchor layer between the barrier layer 14 and the layer below the barrier layer 14. In this case, the adhesion between the barrier layer 14 and the layer below the barrier layer 14 is enhanced by the anchor layer. Alternatively, the solid-state image sensor 10 may have an anchor layer between the barrier layer 14 and the layer above the barrier layer 14. In this case, the adhesion between the barrier layer and the layer above the barrier layer is enhanced by the anchor layer. The material forming the anchor layer is, for example, a polyfunctional acrylic resin or a silane coupling agent.

[0207] The layer structure of the barrier layer 14 may be a single layer structure consisting of a single compound, a stacked structure of layers consisting of a single compound, or a stacked structure of layers consisting of mutually different compounds.

[0208] The barrier layer 14 may also function as a planarizing layer that fills the step difference formed between the surface of the infrared light cut filter 13 and the surface of the infrared light pass filter 12P. The filter 10F for the solid-state image sensor does not need to have a barrier layer 14. Even in this case, it is possible to obtain the same effect as described in (1) above.

[0209] [others] The thicknesses of the color filters 12R, 12G, and 12B may be equal to or different from those of the infrared light pass filter 12P. For example, the thickness of the color filters 12R, 12G, and 12B may be between 0.5 μm and 5 μm.

[0210] The color filter may be a three-color filter including a cyan filter, a yellow filter, and a magenta filter. Alternatively, the color filter may be a four-color filter including a cyan filter, a yellow filter, a magenta filter, and a black filter. Alternatively, the color filter may be a four-color filter including a transparent filter, a yellow filter, a red filter, and a black filter.

[0211] Each color filter 12R, 12G, and 12B may have the same thickness as the infrared light pass filter 12P, or they may have different thicknesses. The thickness of each color filter 12R, 12G, and 12B may be, for example, 0.5 μm or more and 5 μm or less.

[0212] The materials forming the infrared light cut filter 13 include additives such as light stabilizers, antioxidants, heat stabilizers, and antistatic agents, and the infrared light cut filter 13 may include additives that provide functions other than absorbing infrared light.

[0213] • In the solid-state image sensor 10, the oxygen permeability of the stacked structure located on the incident surface 15S side with respect to the infrared light cut filter 13 is 5.0 cc / m³. 2 The oxygen permeability may be less than / day / atm. For example, the laminated structure may consist of other functional layers such as a planarization layer or an adhesion layer, and together with each microlens, its oxygen permeability may be 5.0 cc / m³. 2 It can also be under / day / atm.

[0214] The solid-state image sensor 10 may be equipped with a bandpass filter on the light incident surface side for multiple microlenses. The bandpass filter is a filter that transmits only light with specific wavelengths of visible light and near-infrared light, and has a function similar to that of an infrared light cut filter 13. That is, the bandpass filter can cut out unwanted infrared light that can be detected by the photoelectric conversion elements 11R, 11G, and 11B for each color. This makes it possible to improve the detection accuracy of visible light by the photoelectric conversion elements 11R, 11G, and 11B for each color, and the detection accuracy of near-infrared light with wavelengths in the 850nm or 940nm band, which is the target of detection by the photoelectric conversion element 11P for infrared light. [Explanation of Symbols]

[0215] 10…Solid-state image sensor 10F...Filter for solid-state image sensors 11…Photoelectric conversion element 12R…Red filter 12G...Green filter 12B... Blue filter 12P... Infrared light pass filter 13…Infrared light cut filter 13H...Through hole 14… Barrier layer 15B... Microlens for blue light 15G... Microlens for green 15P…Microlens for infrared light 15R… Microlens for red light

Claims

1. A polymethine, and a cyanine dye comprising a cation located at each end of the polymethine and having a nitrogen-containing heterocycle, and a tris(pentafluoroethyl)trifluorophosphate anion, An acrylic copolymer comprising a first repeating unit represented by the following formula (1) or formula (2), and having an acid value of 50 KOH mg / g or more and 110 KOH mg / g or less, It contains naphthoquinone diazide compounds, The weight of the naphthoquinone diazide compound is 5% by weight or more and 30% by weight or less relative to the weight of the acrylic copolymer. Infrared light cut filter. 【Chemistry 1】 【Chemistry 2】 However, in formula (1), R1 is a hydrogen atom or a methyl group, R2 is an organic group having one or more carbon atoms, and R3 is a carboxyl group. Also, in formula (2), R4 is a hydrogen atom or a methyl group.

2. The average molecular weight of the acrylic copolymer is between 3,000 and 150,000. The infrared light cut filter according to claim 1.

3. An infrared light cut filter according to claim 1 or 2, The infrared light cut filter is covered by a barrier layer that suppresses the transmission of oxidation sources that oxidize the infrared light cut filter. Filters for solid-state image sensors.

4. Photoelectric conversion element, The filter for a solid-state image sensor according to claim 3 comprises Solid-state image sensor.

5. To form an infrared light cut filter comprising a polymethine, a cyanine dye containing a cation having two nitrogen-containing heterocycles located at each end of the polymethine, and a tris(pentafluoroethyl)trifluorophosphate anion, an acrylic copolymer having an acid value of 50 KOH mg / g or more and 110 KOH mg / g or less, and a naphthoquinone diazide compound, This includes patterning the infrared light cut filter by photolithography, The weight of the naphthoquinone diazide compound is 5% by weight or more and 30% by weight or less relative to the weight of the acrylic copolymer. A method for manufacturing filters for solid-state image sensors. 【Transformation 3】 【Chemistry 4】 However, in formula (1), R1 is a hydrogen atom or a methyl group, R2 is an organic group having one or more carbon atoms, and R3 is a carboxyl group. Also, in formula (2), R4 is a hydrogen atom or a methyl group.

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