KR102122293B1 - Resin composition for forming microlens - Google Patents

Abstract

(식 중, X는 시클로헥실기 또는 페닐기를 나타내고, Y는 페닐기, 비페닐릴기 또는 나프틸기를 나타내고, R⁰은 각각 독립적으로 수소원자 또는 메틸기를 나타내고, R¹은 수소원자 또는 탄소원자수 1 내지 3의 알킬기를 나타내고, R²는 탄소원자수 1 내지 10의 직쇄상, 분지쇄상 또는 환상의 알킬기를 나타내고, R¹과 R²는 서로 결합하여 4 내지 7원환의 함산소환구조를 형성할 수도 있고, R³은 단결합 또는 탄소원자수 1 내지 5의 알킬렌기를 나타내고, 해당 알킬렌기는 그 중에 에테르결합을 가질 수도 있고, R⁴는 에폭시기, 또는 에폭시환을 갖는 탄소원자수 5 내지 12의 유기기를 나타낸다.)A resin composition for forming a microlens containing a copolymer having structural units represented by the following formulas (1), (2), (3) and (4), and a solvent is provided.

(Wherein, X represents a cyclohexyl group or a phenyl group, Y represents a phenyl group, a biphenylyl group or a naphthyl group, R ⁰ each independently represents a hydrogen atom or a methyl group, R ¹ is a hydrogen atom or a number of carbon atoms 1 to Represents an alkyl group of 3, R ² represents a straight, branched or cyclic alkyl group having 1 to 10 carbon atoms, and R ¹ and R ² may combine with each other to form a 4 to 7 membered oxygen-containing ring structure, R ³ represents a single bond or an alkylene group having 1 to 5 carbon atoms, the alkylene group may have an ether bond therein, and R ⁴ represents an epoxy group or an organic group having 5 to 12 carbon atoms having an epoxy ring. )

Description

Resin composition for microlens formation {RESIN COMPOSITION FOR FORMING MICROLENS}

The present invention relates to a resin composition for forming a micro lens. More specifically, it relates to a resin composition used to form a microlens by an etchback (etchback) method.

Recently, as the high definition of the CCD/CMOS image sensor progresses, an improvement in sensor sensitivity is required, and for a mounted micro lens, high transparency or high heat resistance is required.

As one of the manufacturing methods of the microlens for CCD/CMOS image sensor, the etch-back method is known (Patent Document 1 and Patent Document 2). That is, a resist pattern is formed on the resin layer for microlenses formed on the color filter layer, and the resist pattern is reflowed by heat treatment to form a lens pattern. The lens pattern formed by reflowing the resist pattern is etched back as an etching mask, and a microlens is produced by etching back the resin layer for the microlens layer and transferring the lens pattern shape to the resin layer for microlens.

In the etch-back method, the dry etching rate X of the resist film and the dry etching rate Y of the resin layer for microlenses are equivalent (for example, X:Y=) in faithfully transferring the lens pattern shape to the lower layer resin layer for microlenses. 1:0.8 to 1.2) is required (Patent Document 3 and Patent Document 4).

Japanese Patent Publication H1-10666 Japanese Patent Publication H6-112459 International Publication No. 2013/005619 International Publication No. 2013/035569

The present invention has been made on the basis of the above circumstances, and its purpose is to provide a thermosetting resin composition excellent in storage stability, which can form a cured film having excellent transparency, heat resistance, solvent resistance, flatness and a dry etching rate equivalent to a resist film. Is to provide. Another object of the present invention is to provide a microlens having excellent transparency, heat resistance and solvent resistance.

The inventors of the present invention conducted a courtesy study to solve the above problems, and as a result, the present invention has been completed.

That is, this invention is the resin composition for microlens formation containing the copolymer which has a structural unit represented by following formula (1), Formula (2), Formula (3), and Formula (4), and a solvent.

[Formula 1]

(Wherein, X represents a cyclohexyl group or a phenyl group, Y represents a phenyl group, a biphenylyl group or a naphthyl group, R ⁰ each independently represents a hydrogen atom or a methyl group, R ¹ is a hydrogen atom or a number of carbon atoms 1 to Represents an alkyl group of 3, R ² represents a straight, branched or cyclic alkyl group having 1 to 10 carbon atoms, and R ¹ and R ² may combine with each other to form a 4 to 7 membered oxygen-containing ring structure, R ³ represents a single bond or an alkylene group having 1 to 5 carbon atoms, the alkylene group may have an ether bond therein, and R ⁴ represents an epoxy group or an organic group having 5 to 12 carbon atoms having an epoxy ring. )

This invention is also a cured film obtained from the said resin composition for microlens formation. Furthermore, the present invention is a microlens made of the resin composition for forming the microlens and a method of manufacturing the same. The microlens is produced by, for example, the etch-back method described above. That is, forming a resin layer by applying and baking the resin composition for forming a microlens of the present invention on a color filter layer, forming a resist pattern using a resist composition on the resin layer, and forming the resist pattern. This microlens is produced by a method comprising reflowing to form a lens pattern, and etching back the resin layer using the lens pattern as an etching mask. The said reflow is performed by heating the said resist pattern at the temperature of glass transition temperature (Tg) or more and less than 200 degreeC of the said resist pattern.

In the resin composition for forming a microlens of the present invention, since the copolymer contained in the composition is a self-crosslinking type, it is not necessary to add a crosslinking agent. Since the carboxyl group is blocked, it has excellent storage stability. Furthermore, the film formed of the resin composition for forming a microlens of the present invention has excellent transparency, heat resistance, solvent resistance, a glass transition temperature (Tg) of 200°C or higher, and an etching rate equivalent to a resist film.

As described above, the film formed of the resin composition for forming a microlens of the present invention is colored in a microlens when heat treatment at a high temperature is performed in the forming process or a forming process of peripheral devices such as wiring. The possibility that the shape is deformed can be significantly reduced. Further, in the case of forming a resin layer with the resin composition for forming a microlens of the present invention and applying a resist solution thereon, and when forming an electrode/wiring after the microlens is formed, mixing with a resist, an organic solvent Also, problems such as deformation and peeling of the microlenses can be significantly reduced. Therefore, the resin composition for forming a microlens of the present invention is suitable as a material for forming a microlens.

The present invention is a resin composition containing a copolymer and a solvent. Hereinafter, each component is explained in full detail. The solid content excluding the solvent in the resin composition of the present invention is usually 1% by mass to 50% by mass.

<Copolymer>

The copolymer contained in the resin composition of the present invention is a copolymer having structural units represented by the formulas (1), (2), (3) and (4) described above.

N-cyclohexyl maleimide and N-phenyl maleimide are mentioned as a specific example of the compound (monomer) which forms the structural unit represented by said formula (1). These compounds may be used alone or in combination of two or more.

As specific examples of the compound (monomer) forming the structural unit represented by the formula (2), styrene, α-methylstyrene, 2-vinylbiphenyl, 3-vinylbiphenyl, 4-vinylbiphenyl, 1- Vinyl naphthalene and 2-vinyl naphthalene. These compounds may be used alone or in combination of two or more.

The structural unit represented by the formula (3) is, for example, a structural unit represented by the following formula (3-1) or formula (3-2).

[Formula 2]

(In the formula, R ⁰ each independently represents a hydrogen atom or a methyl group, R ² represents a straight, branched or cyclic alkyl group having 1 to 10 carbon atoms, and b represents 1 or 2.)

Specific examples of the compound (monomer) forming the structural unit represented by the formula (3) include 1-methoxyethyl (meth)acrylate, 1-ethoxyethyl (meth)acrylate, and 1-propoxyethyl (Meth)acrylate, 1-isopropoxyethyl (meth)acrylate, 1-n-butoxyethyl (meth)acrylate, 1-tert-butoxyethyl (meth)acrylate, 1-n-hexyloxy And monomers such as ethyl (meth)acrylate, 1-cyclohexyloxyethyl (meth)acrylate, and tetrahydro-2H-pyran-2-yl (meth)acrylate. Meanwhile, these monomers may be used alone or in combination of two or more.

The compound (monomer) forming the structural unit represented by the formula (3) is a method of polymerizing acrylate or methacrylate having a protected carboxyl group obtained by reacting acrylic acid or methacrylic acid with an alkenyl ether compound, or acrylic acid Or it is obtained by a method of reacting a polymer of methacrylic acid with an alkenyl ether compound.

The alkenyl ether compound used herein is a compound represented by the following formula (5).

[Formula 3]

(Wherein, R ¹ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R ² represents a straight, branched or cyclic alkyl group having 1 to 10 carbon atoms, and R ¹ and R ² are bonded to each other It is also possible to form an oxygen-containing ring structure of 4 to 7-membered rings.)

The reaction of a compound having a carboxyl group and an alkenyl ether compound can be performed, for example, by using monooctyl phosphate as one of the phosphoric acid esters as a catalyst and stirring at 70°C.

Examples of the alkenyl ether compound represented by the formula (5) include, for example, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, tert-butyl vinyl ether, Aliphatic vinyl ether compounds such as n-hexyl vinyl ether, cyclohexyl vinyl ether, 2-ethylhexyl vinyl ether, norbornyl vinyl ether, 1-adamantyl vinyl ether, and 2-adamantyl vinyl ether, 2,3-di And cyclic vinyl ether compounds such as hydrofuran, 4-methyl-2,3-dihydrofuran and 2,3-dihydro-4H-pyran.

The structural unit represented by the formula (4) is, for example, a structural unit represented by the following formula (4-1), formula (4-2) or formula (4-3).

[Formula 4]

(In the formula, R ⁰ each independently represents a hydrogen atom or a methyl group.)

Specific examples of the compound (monomer) forming the structural unit represented by the formula (4), glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, 3,4- And epoxycyclohexylmethyl (meth)acrylate. These monomers may be used alone or in combination of two or more.

In the copolymer having a structural unit represented by the formula (1), formula (2), formula (3) and formula (4), the structural unit represented by the formula (1), represented by the formula (2) The content of the structural unit represented by the formula (1) is 5 mol% to 80 mol% with respect to 100 mol% of the sum of the structural units, the structural unit represented by the formula (3) and the structural unit represented by the formula (4) Is, preferably 10 mol% to 70 mol%, the content of the structural unit represented by the formula (2) is 5 mol% to 80 mol%, preferably 10 mol% to 70 mol%, the structural unit represented by the formula (3) The content of is 5 mol% to 40 mol%, preferably 10 mol% to 30 mol%, the content of the structural unit represented by the formula (4) is 5 mol% to 40 mol%, preferably 10 mol% to 30 mol%.

The weight average molecular weight of the copolymer is usually 1,000 to 100,000, and preferably 3,000 to 50,000. On the other hand, the weight average molecular weight is a value obtained by using polystyrene as a standard sample by gel permeation chromatography (GPC).

Moreover, content of the said copolymer in the resin composition of this invention is 1 mass%-99 mass% normally based on content in the solid content of the said resin composition, Preferably it is 5 mass%-95 mass %.

In the present invention, the method for obtaining the copolymer is not particularly limited, but generally, the compound forming the structural unit represented by the formula (1), formula (2), formula (3) and formula (4) (Monomer) is obtained by polymerization in a solvent in the presence of a polymerization initiator, usually at a temperature of 50°C to 120°C. The copolymer obtained in this way is usually in the form of a solution dissolved in a solvent, and can be used in the resin composition of the present invention without isolation in this state.

Further, the solution of the copolymer obtained as described above is put into a poor solvent such as hexane, diethyl ether, methanol, and water, which is stirred, to reprecipitate the copolymer, and the resulting precipitate is filtered and washed, followed by normal pressure or The copolymer can be powdered by drying at room temperature or heating under low pressure. Through this operation, a polymerization initiator or an unreacted compound coexisting with the copolymer can be removed. In the present invention, the powder of the copolymer may be used as it is, or the powder may be redissolved in a solvent described later, for example, and used in the form of a solution.

The method for preparing the resin composition of the present invention is not particularly limited, but, for example, a solvent having a copolymer having structural units represented by the formulas (1), (2), (3) and (4) The method of dissolving in and making it a uniform solution is mentioned. Furthermore, in a suitable step of this preparation method, a method of adding and mixing other additives as necessary may be mentioned.

The solvent is not particularly limited as long as it dissolves the copolymer. Examples of such a solvent include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol, Propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether, propylene glycol monobutyl Acetate, toluene, xylene, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-hydroxypropionate ethyl, 2-hydroxy-2-methylpropionate ethyl, ethyl ethoxyacetate, ethyl hydroxyacetate, 2-hydroxy Methyl hydroxy-3-methylbutanoate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl acetate, butyl acetate, ethyl lactate, lactic acid And butyl, 2-heptanone and γ-butyrolactone. These solvents may be used alone or in combination of two or more.

Among these solvents, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, 2-heptanone, ethyl lactate, butyl lactate, from the viewpoint of improving the leveling property of the coating film formed by applying the resin composition of the present invention onto a substrate. Cyclopentanone and cyclohexanone are preferred.

Further, the resin composition of the present invention may contain a surfactant for the purpose of improving coatability.

Examples of the surfactant include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether and polyoxyethylene oleyl ether, and polyoxyethylene octylphenyl. Polyoxyethylene alkylaryl ethers such as ether and polyoxyethylene nonylphenyl ether, polyoxyethylene-polyoxypropylene block copolymers, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan Sorbitan fatty acid esters such as monooleate, sorbitan trioleate, sorbitan tristearate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, Nonionic surfactants, such as polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tristearate, and other polyoxyethylene sorbitan fatty acid esters, EFTOP (EFTOP) [registered trademark] EF301, EFTOP EF303, EFTOP EF352 (above, manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.), MEGAFAC (registered trademark) F-171, MEGAFAC F-173, MEGAFAC R-30, MEGAFAC R-40, MEGAFAC R-40-LM (Above, DIC CORPORATION), FLUORAD (Flora-de) FC430, FLUORAD FC431 (above, Sumitomo 3M Ltd.), ASAHI GUARD (registered trademark) AG710, SURFLON (sa-Fron) (registered trademark) 】 S-382, SURFLON SC101, SURFLON SC102, SURFLON SC103, SURFLON SC104, SURFLON SC105, SURFLON SC106 (manufactured by Asahi Glass Co., Ltd.), FTX-206D, FTX-212D, FTX-218, FTX-220D, FTX Fluorine surfactants such as FTERGENT series (manufactured by Neos Co., Ltd.) such as -230D, FTX-240D, FTX-212P, FTX-220P, FTX-228P, FTX-240G , Organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.). These surfactants may be used alone or in combination of two or more.

Moreover, when the said surfactant is used, content in the resin composition of this invention is 3 mass% or less, preferably 1 mass% or less, more preferably based on content in the solid content of the said resin composition, More preferably Is 0.5% by mass or less.

In addition, the resin composition of the present invention may contain additives such as a crosslinking agent, a curing aid, a UV absorber, a sensitizer, a plasticizer, an antioxidant, a light stabilizer, and an adhesion aid, as necessary, unless the effects of the present invention are inhibited. Can be.

Hereinafter, a method of manufacturing the microlens of the present invention, which is a typical use example of the cured film obtained from the resin composition of the present invention, will be described. This method includes the following four steps.

First, a substrate {for example, a semiconductor substrate such as silicon coated with a silicon oxide film, a semiconductor substrate such as silicon coated with a silicon nitride film or a silicon oxynitride film, a semiconductor substrate such as silicon with a color filter, a silicon nitride substrate, a quartz substrate. , Glass substrate (including alkali-free glass, low-alkali glass, crystallized glass), ITO film-formed glass substrate}, after applying the resin composition of the present invention by a suitable coating method such as spinner, coater, hot plate, etc. It is a step of forming a resin layer for a microlens by baking and curing using a heating means.

The baking conditions are suitably selected within a baking temperature of 80°C to 300°C and a baking time of 0.3 minutes to 60 minutes. Baking can also be carried out in two or more steps.

Moreover, as a film thickness of the film formed from the resin composition of this invention, it is 0.001 micrometers-100 micrometers, for example, Preferably it is 0.01 micrometers-10 micrometers.

Thereafter, a resist solution is applied onto a resin layer for a microlens formed from the resin composition of the present invention, exposed through a predetermined mask, heated (PEB) after exposure if necessary, and alkali developed, rinsed, and dried. This is a step of forming a predetermined resist pattern. For exposure, for example, g-ray, i-ray, KrF excimer laser, ArF excimer laser can be used.

Subsequently, by heat treatment, the resist pattern is reflowed to form a lens pattern. It is a step of producing a microlens by etching the lens pattern again as an etching mask and etching back the resin layer for the microlens layer, and transferring the lens pattern shape to the resin layer for microlenses.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

(Measurement of Weight Average Molecular Weight of the Copolymer Obtained)

Device: GPC system made by JASCO Corporation

Column: Shodex (registered trademark) KF-804L and KF-803L

Column oven: 40℃

Flow rate: 1 mL/min

Eluent: Tetrahydrofuran

[Synthesis of copolymers]

<Synthesis Example 1>

N-phenylmaleimide 5.0g, 2-vinyl naphthalene 4.5g, 1-n-butoxyethyl methacrylate 3.6g, 3,4-epoxycyclohexylmethylmethacrylate (CYCLOMER (registered trademark) M100 (manufactured by Daicel Corporation) )) After dissolving 3.8 g and 0.84 g of 2,2'-azobisisobutyronitrile in 41.2 g of cyclohexanone, this solution was placed in a flask maintaining 11.8 g of cyclohexanone at 70°C for 4 hours. Dropped over. After completion of dropping, the mixture was reacted again for 18 hours to obtain a copolymer solution (solid content concentration: 25% by mass). The weight average molecular weight Mw of the obtained copolymer was 30,000 (in terms of polystyrene).

<Synthesis Example 2>

N-phenylmaleimide 5.0g, 2-vinyl naphthalene 5.9g, 1-n-butoxyethyl methacrylate 2.7g, 4-hydroxybutyl acrylate glycidyl ether (4HBAGE (manufactured by Nippon Kasei Chemical Company Limited)) After 2.9 g and 0.83 g of 2,2'-azobisisobutyronitrile were dissolved in 40.5 g of cyclohexanone, the solution was added dropwise over 4 hours in a flask maintaining 11.6 g of cyclohexanone at 70°C. Did. After completion of dropping, the mixture was reacted again for 18 hours to obtain a copolymer solution (solid content concentration: 25% by mass). The weight average molecular weight Mw of the obtained copolymer was 20,000 (polystyrene conversion).

<Synthesis Example 3>

8.5 g of N-phenylmaleimide, 5.3 g of 4-vinylbiphenyl, 1.8 g of 1-n-butoxyethyl methacrylate, 1.4 g of glycidyl methacrylate, and 2,2'-azobisisobutyronitrile After 0.85 g was dissolved in 41.7 g of cyclohexanone, this solution was added dropwise over 4 hours in a flask maintaining 11.9 g of cyclohexanone at 70°C. After completion of dropping, the mixture was reacted again for 18 hours to obtain a copolymer solution (solid content concentration: 25% by mass). The weight average molecular weight Mw of the obtained copolymer was 22,000 (polystyrene conversion).

<Synthesis Example 4>

3.5 g of N-phenylmaleimide, 10.9 g of 4-vinylbiphenyl, 1.9 g of 1-n-butoxyethyl methacrylate, 1.5 g of glycidyl methacrylate, and 2,2'-azobisisobutyronitrile After 0.90 g was dissolved in 43.5 g of cyclohexanone, this solution was added dropwise over 4 hours in a flask maintaining 12.5 g of cyclohexanone at 70°C. After completion of dropping, the mixture was reacted again for 18 hours to obtain a copolymer solution (solid content concentration: 25% by mass). The weight average molecular weight Mw of the obtained copolymer was 18,000 (polystyrene conversion).

<Synthesis Example 5>

3.5 g of N-cyclohexylmaleimide, 10.5 g of 4-vinylbiphenyl, 1.7 g of tetrahydro-2H-pyran-2-ylmethacrylate, 1.4 g of glycidyl methacrylate, and 2,2'-azobis After 0.86 g of isobutyronitrile was dissolved in 42.0 g of cyclohexanone, this solution was added dropwise over 4 hours into a flask where 12.0 g of cyclohexanone was maintained at 70°C. After completion of dropping, the mixture was reacted again for 18 hours to obtain a copolymer solution (solid content concentration: 25% by mass). The weight average molecular weight Mw of the obtained copolymer was 16,000 (in terms of polystyrene).

<Synthesis Example 6>

N-cyclohexylmaleimide 3.5g, 4-vinyl biphenyl 10.5g, 2-hydroxyethyl methacrylate 1.3g, 2-(O-[1'-methylpropylideneamino]carboxyamino)ethyl methacrylate ( Karenz (registered trademark) 2.4 g of MOI-BM (manufactured by Showa Denko KK)) and 0.88 g of 2,2'-azobisisobutyronitrile were dissolved in 43.4 g of cyclohexanone, and then this solution was cyclohexanone. 12.4 g was added dropwise over 4 hours in a flask maintained at 70°C. After completion of dropping, the mixture was reacted again for 18 hours to obtain a copolymer solution (solid content concentration: 25% by mass). The weight average molecular weight Mw of the obtained copolymer was 19,000 (polystyrene conversion).

<Synthesis Example 7>

N-phenylmaleimide 3.5g, 2-vinylnaphthalene 7.8g, 4-hydroxybutyl acrylate 2.2g, 2-(O-[1'-methylpropylideneamino]carboxyamino)ethyl methacrylate (Karenz[registered Trademark] MOI-BM (manufactured by Showa Denko KK)) 3.7 g, and 0.86 g of 2,2'-azobisisobutyronitrile were dissolved in 42.0 g of cyclohexanone, and then this solution was dissolved in 12.0 g of cyclohexanone. Dropping was carried out over 4 hours in a flask maintained at 70°C. After completion of dropping, the mixture was reacted again for 18 hours to obtain a copolymer solution (solid content concentration: 25% by mass). The weight average molecular weight Mw of the obtained copolymer was 21,000 (polystyrene conversion).

<Synthesis Example 8>

N-phenylmaleimide 4.0g, styrene 2.4g, 2-vinyl naphthalene 7.1g, 2-hydroxyethyl methacrylate 1.5g, 2-[(3,5-dimethylpyrazolyl)carboxyamino]ethyl methacrylate ( Karenz (registered trademark) 2.9 g of MOI-BP (manufactured by Showa Denko KK)) and 0.90 g of 2,2'-azobisisobutyronitrile were dissolved in 43.9 g of cyclohexanone, and then this solution was cyclohexanone. 12.6 g was added dropwise over 4 hours in a flask maintained at 70°C. After completion of dropping, the mixture was reacted again for 18 hours to obtain a copolymer solution (solid content concentration: 25% by mass). The weight average molecular weight Mw of the obtained copolymer was 15,000 (polystyrene conversion).

<Synthesis Example 9>

Styrene 12.0 g, 2-hydroxyethyl methacrylate 1.9 g, 2-(O-[1'-methylpropylideneamino]carboxyamino) ethyl methacrylate (Karenz (registered trademark) MOI-BM (manufactured by Showa Denko KK )) After dissolving 3.5 g, and 0.87 g of 2,2'-azobisisobutyronitrile in 42.5 g of cyclohexanone, the solution was placed in a flask maintaining 12.2 g of cyclohexanone at 70°C for 4 hours. Dropped over. After completion of dropping, the mixture was reacted again for 18 hours to obtain a copolymer solution (solid content concentration: 25% by mass). The weight average molecular weight Mw of the obtained copolymer was 16,000 (in terms of polystyrene).

<Synthesis Example 10>

14.0 g of 2-vinyl naphthalene, 2.1 g of 1-n-butoxyethyl methacrylate, 1.6 g of glycidyl methacrylate, and 1.3 g of 2,2'-azobisisobutyronitrile were added to 44.3 g of cyclohexanone. After dissolving, 12.6 g of cyclohexanone was added dropwise over 4 hours in a flask maintained at 70°C. After completion of dropping, the mixture was reacted again for 18 hours to obtain a copolymer solution (solid content concentration: 25% by mass). The weight average molecular weight Mw of the obtained copolymer was 7,000 (polystyrene conversion).

<Synthesis Example 11>

2-vinyl naphthalene 8.0 g, 2-hydroxyethyl methacrylate 3.4 g, 2-(O-[1'-methylpropylideneamino]carboxyamino) ethyl methacrylate (Karenz [trademark] MOI-BM (Showa Denko KK))) After dissolving 6.3 g and 0.88 g of 2,2'-azobisisobutyronitrile in 43.3 g of cyclohexanone, this solution was placed in a flask maintaining 12.4 g of cyclohexanone at 70°C. It was dripped over 4 hours. After completion of dropping, the mixture was reacted again for 18 hours to obtain a copolymer solution (solid content concentration: 25% by mass). The weight average molecular weight Mw of the obtained copolymer was 20,000 (polystyrene conversion).

<Synthesis Example 12>

9.0 g of 4-vinyl biphenyl, 4.7 g of 1-n-butoxyethyl methacrylate, 3.6 g of glycidyl methacrylate, and 0.86 g of 2,2'-azobisisobutyronitrile 42.1 g of cyclohexanone After dissolving in, this solution was added dropwise over 4 hours in a flask where 12.0 g of cyclohexanone was kept at 70°C. After completion of dropping, the mixture was reacted again for 18 hours to obtain a copolymer solution (solid content concentration: 25% by mass). The weight average molecular weight Mw of the obtained copolymer was 14,000 (polystyrene conversion).

<Synthesis Example 13>

8.0 g of N-phenylmaleimide, 3.0 g of 2-hydroxyethyl methacrylate, 2-[(3,5-dimethylpyrazolyl)carbonylamino]ethyl methacrylate (Karenz (registered trademark) MOI-BP (Showa Denko KK))) After dissolving 5.8g and 0.84g of 2,2'-azobisisobutyronitrile in 41.2g of cyclohexanone, this solution was placed in a flask in which 11.8g of cyclohexanone was kept at 70°C. It was dripped over 4 hours. After completion of dropping, the mixture was reacted again for 18 hours to obtain a copolymer solution (solid content concentration: 25% by mass). The weight average molecular weight Mw of the obtained copolymer was 19,000 (polystyrene conversion).

[Preparation of resin composition for forming microlens]

<Example 1>

MEGAFAC (registered trademark) R-30 (manufactured by DIC CORPORATION) as a surfactant was dissolved in 40.0 g of the copolymer obtained in Synthesis Example 1 (including 10.0 g of solid content). Then, using a micro filter made of polyethylene having a pore diameter of 0.10 μm, it was filtered to prepare a resin composition for forming a micro lens.

<Example 2>

MEGAFAC [registered trademark] R-30 (manufactured by DIC CORPORATION) as a surfactant was dissolved in 40.0 g (containing 10.0 g of solid content) of the copolymer solution obtained in Synthesis Example 2. Then, using a micro filter made of polyethylene having a pore diameter of 0.10 μm, it was filtered to prepare a resin composition for forming a micro lens.

<Example 3>

MEGAFAC (registered trademark) R-30 (manufactured by DIC CORPORATION) as a surfactant was dissolved in 40.0 g of a copolymer obtained in Synthesis Example 3 (containing 10.0 g of solid content). Then, using a micro filter made of polyethylene having a pore diameter of 0.10 μm, it was filtered to prepare a resin composition for forming a micro lens.

<Example 4>

MEGAFAC (registered trademark) R-30 (manufactured by DIC CORPORATION) as a surfactant was dissolved in 40.0 g of the copolymer obtained in Synthesis Example 4 (containing 10.0 g of solid content). Then, using a micro filter made of polyethylene having a pore diameter of 0.10 μm, it was filtered to prepare a resin composition for forming a micro lens.

<Example 5>

MEGAFAC (registered trademark) R-30 (manufactured by DIC CORPORATION) as a surfactant was dissolved in 40.0 g of the copolymer obtained in Synthesis Example 5 (containing 10.0 g of solid content). Then, using a micro filter made of polyethylene having a pore diameter of 0.10 μm, it was filtered to prepare a resin composition for forming a micro lens.

<Reference Example 1>

MEGAFAC (registered trademark) R-30 (manufactured by DIC CORPORATION) as a surfactant was dissolved in 40.0 g of the copolymer obtained in Synthesis Example 6 (containing 10.0 g of solid content). Then, using a micro filter made of polyethylene having a pore diameter of 0.10 μm, it was filtered to prepare a resin composition for forming a micro lens.

<Reference Example 2>

MEGAFAC (registered trademark) R-30 (manufactured by DIC CORPORATION) as a surfactant was dissolved in 40.0 g of the copolymer obtained in Synthesis Example 7 (containing 10.0 g of solid content). Then, using a micro filter made of polyethylene having a pore diameter of 0.10 μm, it was filtered to prepare a resin composition for forming a micro lens.

<Reference Example 3>

MEGAFAC (registered trademark) R-30 (manufactured by DIC CORPORATION) as a surfactant was dissolved in 40.0 g of the copolymer obtained in Synthesis Example 8 (including 10.0 g of solid content). Then, using a micro filter made of polyethylene having a pore diameter of 0.10 μm, it was filtered to prepare a resin composition for forming a micro lens.

<Comparative Example 1>

MEGAFAC (registered trademark) R-30 (manufactured by DIC CORPORATION) as a surfactant was dissolved in 40.0 g of the copolymer obtained in Synthesis Example 9 (including 10.0 g of solid content). Then, using a micro filter made of polyethylene having a pore diameter of 0.10 μm, it was filtered to prepare a resin composition for forming a micro lens.

<Comparative Example 2>

MEGAFAC (registered trademark) R-30 (manufactured by DIC CORPORATION) as a surfactant was dissolved in 40.0 g (containing 10.0 g of solid content) of the copolymer solution obtained in Synthesis Example 10. Then, using a micro filter made of polyethylene having a pore diameter of 0.10 μm, it was filtered to prepare a resin composition for forming a micro lens.

<Comparative Example 3>

MEGAFAC (registered trademark) R-30 (manufactured by DIC CORPORATION) as a surfactant was dissolved in 40.0 g (containing 10.0 g of solid content) of the solution of the copolymer obtained in Synthesis Example 11. Then, using a micro filter made of polyethylene having a pore diameter of 0.10 μm, it was filtered to prepare a resin composition for forming a micro lens.

<Comparative Example 4>

MEGAFAC (registered trademark) R-30 (manufactured by DIC CORPORATION) as a surfactant was dissolved in 40.0 g of the copolymer obtained in Synthesis Example 12 (containing 10.0 g of solid content). Then, using a micro filter made of polyethylene having a pore diameter of 0.10 μm, it was filtered to prepare a resin composition for forming a micro lens.

<Comparative Example 5>

MEGAFAC (registered trademark) R-30 (manufactured by DIC CORPORATION) as a surfactant was dissolved in 40.0 g (containing 10.0 g of solid content) of the solution of the copolymer obtained in Synthesis Example 13. Then, using a micro filter made of polyethylene having a pore diameter of 0.10 μm, it was filtered to prepare a resin composition for forming a micro lens.

[Solvent resistance test]

The resin compositions for forming microlenses prepared in Examples 1 to 5, Reference Examples 1 to Reference Example 3 and Comparative Examples 1 to 5 were respectively coated with a spin coater on a silicon wafer and on a hot plate. In this case, baking was performed at 100°C for 1 minute and at 230°C for 10 minutes to form a film having a thickness of 2 µm. For these membranes, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, butyl acetate, 3-methoxypropionate methyl, acetone, methyl isobutyl ketone, 2-heptanone, 2-propanol, and 2.38 mass The test was performed by immersing in an aqueous solution of tetramethylammonium hydroxide (TMAH) at a concentration of 23% under a temperature condition of 23°C for 5 minutes. The film thickness change before and after immersion was measured, and even if one of the above immersion solvents had a film thickness increase or decrease of 5% or more relative to the film thickness before immersion, the film thickness increase or decrease was less than 5% for all solvents. Estimated solvent resistance as “○”. Table 1 shows the evaluation results.

[Measurement of transmittance]

The resin compositions for forming microlenses prepared in Examples 1 to 5, Reference Examples 1 to 3, and Comparative Examples 1 to 5 were coated on a quartz substrate using a spin coater, respectively, on a hot plate. In this case, baking was performed at 100°C for 1 minute and at 230°C for 10 minutes to form a film having a thickness of 2 µm. For these films, the transmittance was measured by changing the wavelength by 2 nm in the range of 400 nm to 800 nm in wavelength using an ultraviolet visible spectrophotometer UV-2550 (manufactured by Shimadzu Corporation). After heating the film at 260° C. for 5 minutes again, the transmittance was measured by changing the wavelength by 2 nm in the range of 400 nm to 800 nm again. Table 1 shows the values of the minimum transmittance measured in the range of 400 nm to 800 nm in wavelength before and after heating at 260° C. for 5 minutes.

[Measurement of dry etching rate]

The etching and etching gas used for the measurement of the dry etching rate are as follows.

Echer: RIE-10NR (manufactured by SAMCO Inc.)

Etching gas: CF ₄

The resin compositions for forming microlenses prepared in Examples 1 to 5, Reference Examples 1 to Reference Example 3 and Comparative Examples 1 to 5 were respectively coated with a spin coater on a silicon wafer and on a hot plate. In this case, baking was performed at 100°C for 1 minute and at 230°C for 10 minutes to form a film having a thickness of 2 µm. The dry etching rate of these films was measured using the above-mentioned etching agent and etching gas. Similarly, a resist solution (THMR-iP1800 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) was coated on a silicon wafer using a spin coater, and on a hot plate at 90°C for 1.5 minutes and at 110°C for 1.5 minutes, Again, baking was performed at 180° C. for 1 minute to form a resist film having a film thickness of 1 μm, and a dry etching rate was measured, and for the resist film, Examples 1 to 5, Reference Examples 1 to 3, and The dry etching rate of the films obtained from the resin composition for microlens formation prepared in Comparative Examples 1 to 5 was obtained.

[Measurement of glass transition temperature (Tg)]

The resin compositions for forming microlenses prepared in Examples 1 to 5, Reference Examples 1 to Reference Example 3 and Comparative Examples 1 to 5 were respectively coated with a spin coater on a silicon wafer and on a hot plate. In this case, baking was performed at 100°C for 1 minute and at 230°C for 10 minutes to form a film having a thickness of 2 µm. These films were peeled from the silicon wafer, and measured using a differential scanning calorimeter DSC3100SR (manufactured by Mac Science Co., Ltd.). Table 1 shows the evaluation results.

[Table 1]

From the results in Table 1, the film formed of the resin composition for forming a microlens of the present invention was of high solvent resistance and high transparency, and had high heat resistance not to be colored even after heating at 260°C. Further, in the etch-back method, the dry etching rate X of the resist film and the dry etching rate Y of the resin layer for microlenses are equal (X:Y=1:) in faithfully transferring the lens pattern shape to the resin layer for microlenses of the lower layer. 0.8 ~ 1.2, preferably X: Y = 1: 0.9 ~ 1.1) is required, the resin composition for forming a micro lens of the present invention has been found to satisfy this. In addition, from the viewpoint of the microlens forming process and the reliability as a permanent member, the Tg of the film formed of the resin composition for microlens formation is preferably 200°C or higher, and more preferably 200°C or higher. 200°C is a temperature above the heating temperature required to form a resist pattern on the film in the process of manufacturing a microlens from the film, and also a temperature above the reflow temperature of the resist pattern. The film formed from the resin composition for forming a microlens of the present invention has a result of satisfying that Tg is 200°C or higher. On the other hand, it was found that the films formed of the resin composition for forming microlenses prepared in Comparative Examples 1 to 5 did not satisfy all the characteristics. All of the films formed of the resin composition for forming microlenses prepared in Reference Examples 1 to 3 had a Tg of 200°C.

Claims (7)

Structural unit represented by the following formula (1),
Structural unit represented by formula (2),
Structural unit represented by formula (3-1) or formula (3-2), and
A resin composition for forming a microlens containing a copolymer having a structural unit represented by formula (4-1), formula (4-2) or formula (4-3), and a solvent.

(Wherein, X represents a cyclohexyl group or a phenyl group, Y represents a biphenylyl group or a naphthyl group, R ⁰ each independently represents a hydrogen atom or a methyl group, R ² is a straight chain having 1 to 10 carbon atoms, Represents a branched or cyclic alkyl group, and b represents 1 or 2.)
According to claim 1,
The copolymer is a resin composition for forming a micro lens having a structural unit represented by the formula (3-1) and a structural unit represented by the formula (1) in which X is a phenyl group.
The method according to claim 1 or 2,
A resin composition for forming a micro lens further comprising a surfactant.
The method according to claim 1 or 2,
The resin composition for forming a micro lens, wherein the copolymer has a weight average molecular weight of 1,000 to 100,000.
A cured film obtained from the resin composition for forming a microlens according to claim 1 or 2.
Forming a resin layer by applying and baking the resin composition for forming a microlens according to claim 1 or 2 on a color filter layer, and forming a resist pattern using the resist composition on the resin layer; And reflowing the resist pattern to form a lens pattern, and etching back the resin layer using the lens pattern as an etching mask. delete