TWI671350B - Resin composition for forming microlens - Google Patents

Abstract

The present invention provides a resin composition for forming a microlens.

The resin composition for forming a microlens of the present invention contains a copolymer having a structural unit represented by the following formula (1), formula (2), formula (3), and formula (4), and a solvent.

(In the formula, X represents cyclohexyl or phenyl, Y represents phenyl, biphenyl, or naphthyl, R ⁰ each independently represents a hydrogen atom or a methyl group, and R ¹ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. , R ² represents a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, R ¹ and R ^{2 are} bonded to each other, and an oxygen-containing ring structure of 4 to 7 member rings can also be formed, R ³ Represents a single bond or an alkylene group having 1 to 5 carbon atoms, and the alkylene group may have an ether bond, 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

The present invention relates to a resin composition for forming a microlens. More specifically, it relates to a resin composition for forming a microlens by an etch-back method.

In recent years, high-resolution CCD / CMOS image sensors have been developed, and it is required to increase the sensitivity of the sensors. Therefore, the mounted microlenses require high transparency or high heat resistance.

An etch-back method, which is one of manufacturing methods of a microlens for a CCD / CMOS image sensor, is known (Patent Literature 1 and Patent Literature 2). That is, a resist pattern is formed on the microlens resin layer formed on the color filter layer, and this resist pattern is re-soldered by heat treatment to form a lens pattern. The lens pattern formed by re-soldering the resist pattern is used as an etching mask to etch back the lower microlens resin layer and transfer the lens pattern shape to the microlens resin layer, thereby fabricating a microlens.

When the etchback method faithfully transfers the lens pattern shape to the underlying microlens resin layer, the dry etching rate X of the resist film and the dry etching rate Y of the microlens resin layer need to be equal (for example, X: Y = 1: 0.8 to 1.2) (Patent Literature 3 and Patent Literature 4).

[Prior technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application Laid-Open No. 1-10666

[Patent Document 2] Japanese Unexamined Patent Publication No. 6-112459

[Patent Document 3] International Publication No. 2013/005619

[Patent Document 4] International Publication No. 2013/035569

The present invention has been completed based on the foregoing circumstances, and an object of the present invention is to provide a storage stability capable of forming a cured film having excellent transparency, heat resistance, solvent resistance, flatness, and dry etching speed equivalent to a resist film. Resin composition with excellent thermosetting properties. Another object of the present invention is to provide a microlens having excellent transparency, heat resistance, and solvent resistance.

The present inventors carefully reviewed the results in order to solve the aforementioned problems, and completed the present invention.

In other words, the present invention is a resin composition for forming a microlens, which contains a copolymer having a structural unit represented by the following formula (1), formula (2), formula (3), and formula (4), and a solvent.

(In the formula, 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, and R ¹ represents a hydrogen atom or a carbon number of 1 to 3 Alkyl group, R ² represents a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, R ¹ and R ^{2 are} bonded to each other, and an oxygen-containing ring structure of 4 to 7 members can also be formed R ³ represents a single bond or an alkylene group having 1 to 5 carbon atoms. The alkylene group may also have an ether bond, and R ⁴ represents an epoxy group or an epoxy ring having 5 to 12 carbon atoms. Organic).

The present invention is a cured film obtained from the resin composition for forming a microlens. In addition, the present invention is a microlens produced from the resin composition for forming a microlens and a method for producing the same. This microlens is produced, for example, by the aforementioned etch-back method. That is, the microlens is produced by a method including the following steps: the resin composition for forming a microlens of the present invention is coated on a color filter layer, and the resin layer is formed on the resin layer by baking; A step of forming a resist pattern using a resist composition, a step of reflowing the aforementioned resist pattern to form a lens pattern, and using the aforementioned lens pattern as an etching mask to etch back the aforementioned Stage of the resin layer. The reflow is above the glass transition temperature (Tg) of the aforementioned resist pattern. The resist pattern is usually heated at a temperature of less than 200 ° C.

Since the resin composition for forming a microlens of the present invention is a self-crosslinking type copolymer, it is not necessary to add a cross-linking agent, and it has thermosetting properties, and the structural unit represented by the above formula (3) Since the carboxyl group is blocked, it is excellent in storage stability. In addition, the film formed from 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 that of a resist film.

As described above, in the step of forming a film formed of the resin composition for forming a microlens of the present invention, or the step of forming peripheral devices such as wiring, high-temperature heat treatment can significantly reduce the possibility of microlens coloration and lens shape deformation. Sex. In addition, when the resin layer is formed from the resin composition for forming a microlens according to the present invention, when a resist solution is applied thereon, and when the electrode / wiring formation step is performed after the microlens is formed, the resin layer is mixed with the resist and caused by an organic solvent. Deformation and peeling of microlenses can also be significantly reduced. Therefore, the resin composition for forming a microlens of the present invention is suitable as a material for forming a microlens.

[Form of Implementing Invention]

The present invention is a resin composition containing a copolymer and a solvent. The details of each component are described below. The solid content after removing the solvent from 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 a structural unit represented by the aforementioned formula (1), formula (2), formula (3), and formula (4).

Specific examples of the compound (monomer) that forms the structural unit represented by the formula (1) include, for example, N-cyclohexylmaleimide and N-phenylmaleimide. These compounds can be used alone or in combination of two or more.

Specific examples of the compound (monomer) forming the structural unit represented by the aforementioned formula (2) include, for example, styrene, α-methylstyrene, 2-vinylbiphenyl, 3-vinylbiphenyl, 4- Vinylbiphenyl, 1-vinylnaphthalene and 2-vinylnaphthalene. These compounds may be used alone or in combination of two or more.

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

(In the formula, each of R ⁰ independently represents a hydrogen atom or a methyl group, R ² represents a linear, 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, for example, 1-methoxyethyl (meth) acrylate, 1-ethoxyethyl (meth) acrylate, 1-propoxyethyl (meth) acrylate, 1-isopropoxyethyl (meth) acrylate, 1-n-butoxyethyl (meth) acrylate, 1-tert-butyl Oxyethyl (meth) acrylate, 1-n-hexyloxyethyl (meth) acrylate, 1-cyclohexyloxyethyl (meth) acrylate, tetrahydro-2H-pyran- A monomer such as 2-yl (meth) acrylate. These monomers may be used alone or in combination of two or more.

The compound (monomer) forming the structural unit represented by the aforementioned formula (3) can be carried out by reacting acrylic acid or methacrylic acid with an alkenyl ether compound to obtain an acrylate or methacrylate having a protected carboxyl group. It is obtained by a method of polymerization or a method of reacting a polymer of acrylic acid or methacrylic acid with an alkenyl ether compound.

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

(In the formula, R ¹ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R ² represents a linear, branched chain, or cyclic alkyl group having 1 to 10 carbon atoms, and R ¹ and R ^{2 are} mutually Bonding can also form an oxygen-containing ring structure with 4 to 7 member rings).

Reaction of a compound having a carboxyl group with an alkenyl ether compound, For example, it can be carried out by using monooctyl phosphate, which is one of the phosphate esters, as a catalyst and stirring at 70 ° C.

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

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

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

Specific examples of the compound (monomer) that forms the structural unit represented by the formula (4) include, for example, glycidyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, glycidyl ether, 3,4-epoxycyclohexylmethyl (meth) acrylate. These monomers can be used alone or in combination of two or more. use.

In the copolymer having the structural units represented by the aforementioned formula (1), (2), (3), and (4), the copolymer has the structure represented by the aforementioned formula (1) and the structure represented by the aforementioned formula (2). The sum of the unit, the structural unit represented by the aforementioned formula (3) and the structural unit represented by the aforementioned formula (4) is 100 mol%, and the content rate of the structural unit represented by the aforementioned formula (1) is 5 mol% to 80 mol%, preferably 10 mol% To 70 mol%, the content rate of the structural unit represented by the foregoing formula (2) is 5 mol% to 80 mol%, preferably 10 mol% to 70 mol%, and the content rate of the structural unit represented by the foregoing formula (3) is 5 mol% to 40 mol% It is preferably 10 mol% to 30 mol%, and the content rate of the structural unit represented by the foregoing formula (4) is 5 mol% to 40 mol%, and preferably 10 mol% to 30 mol%.

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

In addition, the content of the aforementioned copolymer in the resin composition of the present invention is based on the content in the solid content of the resin composition, and is usually 1% to 99% by mass, and preferably 5% to 95% by mass.

In the present invention, the method for obtaining the aforementioned copolymer is not particularly limited, and in general, the compound (monomer) which will form the structural unit represented by the aforementioned formula (1), formula (2), formula (3), and formula (4) ), Obtained by reacting in a solvent in the presence of a polymerization initiator, usually at a temperature of 50 ° C to 120 ° C. The copolymer thus obtained is usually in a solution state dissolved in a solvent, and does not separate in this state, and can be used for the resin composition of the present invention.

In addition, the solution of the copolymer obtained as described above is put into a poor solvent such as hexane, diethyl ether, methanol, water, etc., to reprecipitate the copolymer, and the resulting precipitate is filtered and washed. The copolymer can be made into powder by drying at room temperature or heating and drying under normal pressure or reduced pressure. By doing so, the polymerization initiator or unreacted compound coexisting with the aforementioned 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 a solution state.

The method for preparing the resin composition of the present invention is not particularly limited. For example, a copolymer having a structural unit represented by the above formula (1), formula (2), formula (3), and formula (4) is dissolved in a solvent to form Method for homogeneous solution. In addition, for example, there is a method in which another additive is added and mixed at an appropriate stage of the preparation method, if necessary.

The solvent is not particularly limited as long as it is a soluble copolymer. Examples of such solvents include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl cellulose acetate, ethyl cellulose acetate, diethylene glycol monomethyl ether, and 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 Ester, propylene glycol monobutyl ether, propylene glycol monobutyl ether acetate, toluene, xylene, methyl ethyl ketone, cyclopentanone, cyclohexanone, ethyl 2-hydroxypropionate, 2-hydroxy-2- Ethyl methyl propionate, ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutyrate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate Ester, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate Esters, ethyl acetate, butyl acetate, ethyl lactate, butyl lactate, 2-heptane, γ-butyrolactone. These solvents can be used alone or in combination of two or more.

Among these solvents, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and propylene glycol monomethyl ether acetate are preferred from the viewpoint of improving the flatness of the coating film formed by coating the resin composition of the present invention on a substrate. -Heptanone, ethyl lactate, butyl lactate, cyclopentanone and cyclohexanone.

The resin composition of the present invention may contain a surfactant for the purpose of improving coating properties.

Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl ethers, polyoxyethylene octylphenyl ether, polyoxyethylene Polyoxyethylene alkylaryl ethers such as ethylene nonylphenyl ether, polyoxyethylene‧polyoxypropylene block copolymers, sorbitan monolaurate, sorbitan monopalmitate, sorbitan mono Sorbitan fatty acid esters such as stearates, sorbitan monooleate, sorbitan trioleate, sorbitan tristearate, polyoxyethylene sorbitan monolaurate, poly Polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tristearate, etc. Nonionic surfactants such as alcohol anhydride fatty acid esters, Eftop [registered trademark] EF301, same as EF303, same as EF352 (the above is made by Mitsubishi Materials Electronics Co., Ltd.), MEGAFAC [registered trademark] F-171, same as F -173, same as R-30, same as R-40, same as R-40-LM (the above is made by DIC (stock)), Fluorad FC430, same as FC431 (above Sumitomo 3M (shares) system), Asahi Guard [registrars Tagged] AG710, Surflon [registered trademark] S-382, same SC101, same SC102, same SC103, same SC104, same SC105, same SC106 (made by Asahi Glass), FTX-206D, FTX-212D, FTX-218, FTX-220D, FTX-230D, FTX-240D, FTX-212P, FTX-220P, FTX-228P, FTX-240G and other ftergent series (manufactured by NEOS) and other fluorine-based surfactants and organosiloxane polymerization KP341 (Shin-Etsu Chemical Industry Co., Ltd.). These surfactants can be used alone or in combination of two or more kinds.

When the aforementioned surfactant is used, the content in the resin composition of the present invention is based on the solid content of the lipid composition, which is 3% by mass or less, preferably 1% by mass or less, and more preferably 0.5% by mass. the following.

In addition, the resin composition of the present invention may contain a cross-linking agent, a curing aid, an ultraviolet absorber, a sensitizer, a plasticizer, an antioxidant, a light stabilizer, and an adhesion aid, as long as the effect of the present invention is not affected. Additives and other additives.

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

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

The baking conditions can be appropriately selected from a baking temperature of 80 to 300 ° C, and a baking time of 0.3 to 60 minutes. Baking can be performed in more than two stages.

The film thickness of the film formed from the resin composition of the present invention is, for example, 0.001 to 100 μm, and preferably 0.01 to 10 μm.

Next, a resin solution for microlenses formed from the resin composition of the present invention is coated with a resist solution, and exposed through a specific photomask, and if necessary, heated after exposure (PEB), developed by alkali, washed, The stage of drying to form a specific resist pattern. For exposure, for example, g-line, i-line, KrF excimer laser, and ArF excimer laser can be used.

Next, the above-mentioned resist pattern is re-soldered to form a lens pattern by heat treatment. This lens pattern is used as an etching mask to etch back the underlying microlens resin layer, and transfer the lens pattern shape to the microlens resin layer to produce a microlens.

[Example]

The following examples illustrate the present invention in more detail, but the present invention is not limited to those examples.

[Measurement of weight average molecular weight of obtained copolymer]

Installation: GPC system made by JASCO Corporation

Column: Shodex [registered trademark] KF-804L and KF-803L

Column oven: 40 ℃

Flow: 1mL / min

Eluent: Tetrahydrofuran

[Synthesis of copolymer] <Synthesis example 1>

5.0 g of N-phenylmaleimide, 4.5 g of 2-vinylnaphthalene, 3.6 g of 1-n-butoxyethyl methacrylate, 3,4-epoxycyclohexylmethylmethyl 3.8 g of acrylate (Cyclomer [registered trademark] M100 ((share) DAICEL))) and 0.84 g of 2,2'-azobisisobutyronitrile were dissolved in 41.2 g of cyclohexanone, and the solution was dropped over 4 hours. In a flask holding 11.8 g of cyclohexanone at 70 ° C. After the completion of the dropping, the reaction was further performed 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>

5.0 g of N-phenylmaleimide, 5.9 g of 2-vinylnaphthalene, 2.7 g of 1-n-butoxyethyl methacrylate, and 4-hydroxybutyl acrylate epoxypropyl ether ( 4HBAGE (manufactured by Nippon Kasei Co., Ltd.)) 2.9 g and 2,2'-azobisisobutyronitrile 0.83 g were dissolved in 40.5 g of cyclohexanone, and this solution was dropped over 11.6 g of cyclohexanone over 4 hours. Keep in a 70 ° C flask. After the dropping was completed, the reaction was allowed to proceed for another 18 hours to obtain a copolymer solution (solid content concentration: 25 mass) %). The weight average molecular weight Mw of the obtained copolymer was 20,000 (in terms of polystyrene).

<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 epoxypropylmethacrylate, After dissolving 0.85 g of 2,2'-azobisisobutyronitrile in 41.7 g of cyclohexanone, this solution was dropped into a flask holding 11.9 g of cyclohexanone at 70 ° C. over 4 hours. After the completion of the dropping, the reaction was further performed 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 equivalent).

<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 epoxypropylmethacrylate, After dissolving 0.90 g of 2,2'-azobisisobutyronitrile in 43.5 g of cyclohexanone, this solution was dropped into a flask holding 12.5 g of cyclohexanone at 70 ° C. over 4 hours. After the completion of the dropping, the reaction was further performed 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 (in terms of polystyrene).

<Synthesis example 5>

3.5 g of N-cyclohexylmaleimide, 10.5 g of 4-vinylbiphenyl, 1.7 g of tetrahydro-2H-pyran-2-yl methacrylate, and epoxypropyl After 1.4 g of methacrylate and 0.86 g of 2,2'-azobisisobutyronitrile were dissolved in 42.0 g of cyclohexanone, this solution was dropped over 4 hours to a flask holding 12.0 g of cyclohexanone at 70 ° C. in. After the completion of the dropping, the reaction was further performed 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 (polystyrene equivalent).

<Synthesis example 6>

3.5 g of N-cyclohexylmaleimide, 10.5 g of 4-vinylbiphenyl, 1.3 g of 2-hydroxyethyl methacrylate, 2- (O- [1'-methylpropylene amine Group] carboxyamino group) ethyl methacrylate (karenz [registered trademark] MOI-BM (manufactured by Showa Denko Corporation)) 2.4 g, and 0.88 g of 2,2'-azobisisobutyronitrile were dissolved in the ring After 43.4 g of hexanone, this solution was dropped into a flask holding 12.4 g of cyclohexanone at 70 ° C. over 4 hours. After the completion of the dropping, the reaction was further performed 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 equivalent).

<Synthesis example 7>

3.5 g of N-phenylmaleimide, 7.8 g of 2-vinylnaphthalene, 2.2 g of 4-hydroxybutyl acrylate, 2- (O- [1'-methylidene) amino group ] Carboxylamino) ethyl methacrylate (Karenz [registered trademark] MOI-BM (manufactured by Showa Denko Corporation)) 3.7 g, and 0.86 g of 2,2'-azobisisobutyronitrile were dissolved in cyclohexyl After 42.0 g of ketones, this solution was dropped into a flask holding 12.0 g of cyclohexanone at 70 ° C. over 4 hours. After dripping is finished, let reaction 18 A copolymer solution (solid content concentration: 25% by mass) was obtained for hours. The weight average molecular weight Mw of the obtained copolymer was 21,000 (polystyrene equivalent).

<Synthesis example 8>

4.0 g of N-phenylmaleimide, 2.4 g of styrene, 7.1 g of 2-vinylnaphthalene, 1.5 g of 2-hydroxyethyl methacrylate, 2-[(3,5-dimethylpyridine Azole group) carboxyamino group] ethyl methacrylate (karenz [registered trademark] MOI-BP (manufactured by Showa Denko Corporation)) 2.9 g, and 0.90 g of 2,2'-azobisisobutyronitrile were dissolved in After 43.9 g of cyclohexanone, this solution was dripped over 4 hours into a flask holding 12.6 g of cyclohexanone at 70 ° C. After the completion of the dropping, the reaction was further performed 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 (in terms of polystyrene).

<Synthesis example 9>

12.0 g of styrene, 1.9 g of 2-hydroxyethyl methacrylate, 2- (O- [1'-methylpropyleneamino] carboxyamino) ethyl methacrylate (karenz [registered trademark] ] MOI-BM (manufactured by Showa Denko Co., Ltd.)) 3.5 g and 2,2'-azobisisobutyronitrile 0.87 g were dissolved in 42.5 g of cyclohexanone, and the solution was dropped over 4 hours on cyclohexanone 12.2 g of ketone was kept in a flask at 70 ° C. After the completion of the dropping, the reaction was further performed 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 (polystyrene equivalent).

<Synthesis example 10>

14.0 g of 2-vinylnaphthalene, 2.1 g of 1-n-butoxyethyl methacrylate, 1.6 g of epoxypropylmethacrylate, and 1.3 g of 2,2'-azobisisobutyronitrile After dissolving in 44.3 g of cyclohexanone, this solution was dropped over 4 hours into a flask holding 12.6 g of cyclohexanone at 70 ° C. After the completion of the dropping, the reaction was further performed 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 (in terms of polystyrene).

<Synthesis example 11>

8.0 g of 2-vinylnaphthalene, 3.4 g of 2-hydroxyethyl methacrylate, and 2- (O- [1'-methylpropyleneamino] carboxyamino) ethyl methacrylate (karenz [Registered Trademark] 6.3 g of MOI-BM (manufactured by Showa Denko Corporation)) and 0.88 g of 2,2'-azobisisobutyronitrile were dissolved in 43.3 g of cyclohexanone, and the solution was dripped over 4 hours. 12.4 g of cyclohexanone was kept in a flask at 70 ° C. After the completion of the dropping, the reaction was further performed 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 (in terms of polystyrene).

<Synthesis example 12>

9.0 g of 4-vinylbiphenyl, 4.7 g of 1-n-butoxyethyl methacrylate, 3.6 g of epoxypropylmethacrylate, and 2,2'-azobisisobutyronitrile After 0.86 g was dissolved in 42.1 g of cyclohexanone, this solution was dropped into a flask holding 12.0 g of cyclohexanone at 70 ° C. over 4 hours. After dripping, The reaction was further performed 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 (in terms of polystyrene).

<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 (manufactured by Showa Denko))) 5.8 g, and 0.82 g of 2,2'-azobisisobutyronitrile were dissolved in 41.2 g of cyclohexanone, and the solution was added for 4 hours. It dripped into the flask which hold | maintained 11.8g of cyclohexanone at 70 degreeC. After the completion of the dropping, the reaction was further performed 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 equivalent).

[Preparation of resin composition for microlens formation] <Example 1>

0.01 g of Megafac [registered trademark] R-30 (manufactured by DIC Corporation) as a surfactant was dissolved in 40.0 g (including 10.0 g of solid content) of the solution of the copolymer obtained in Synthesis Example 1. Then, it filtered using a polyethylene microfilter with a pore diameter of 0.10 micrometer, and prepared the fat composition for microlens formation.

<Example 2>

Make Megafac [registered trademark] R- as a surfactant 30 (manufactured by DIC Corporation) 0.01 g was dissolved in 40.0 g (including 10.0 g of solid content) of the copolymer solution obtained in Synthesis Example 2. Then, it filtered with a polyethylene fine filter with a pore diameter of 0.10 micrometer, and prepared the fat composition for microlens formation.

<Example 3>

0.01 g of Megafac [registered trademark] R-30 (manufactured by DIC Corporation) as a surfactant was dissolved in 40.0 g (including 10.0 g of solid content) of the solution of the copolymer obtained in Synthesis Example 3. Then, it filtered with a polyethylene fine filter with a pore diameter of 0.10 micrometer, and prepared the fat composition for microlens formation.

<Example 4>

0.01 g of Megafac [registered trademark] R-30 (manufactured by DIC (KK)) as a surfactant was dissolved in 40.0 g (including 10.0 g of solid content) of the solution of the copolymer obtained in Synthesis Example 4. Then, it filtered with a polyethylene fine filter with a pore diameter of 0.10 micrometer, and prepared the fat composition for microlens formation.

<Example 5>

0.01 g of Megafac [registered trademark] R-30 (manufactured by DIC Corporation) as a surfactant was dissolved in 40.0 g (including 10.0 g of a solid content) of the solution of the copolymer obtained in Synthesis Example 5. Then, it was filtered with a polyethylene fine filter having a pore size of 0.10 μm to prepare a lipid composition for microlens formation. Thing.

<Reference Example 1>

0.01 g of Megafac [registered trademark] R-30 (manufactured by DIC Corporation) as a surfactant was dissolved in 40.0 g (including 10.0 g of a solid content) of the solution of the copolymer obtained in Synthesis Example 6. Then, it filtered with a polyethylene fine filter with a pore diameter of 0.10 micrometer, and prepared the fat composition for microlens formation.

<Reference Example 2>

0.01 g of Megafac [registered trademark] R-30 (manufactured by DIC (stock)) as a surfactant was dissolved in 40.0 g (including 10.0 g of a solid content) of the solution of the copolymer obtained in Synthesis Example 7. Then, it filtered with a polyethylene fine filter with a pore diameter of 0.10 micrometer, and prepared the fat composition for microlens formation.

<Reference Example 3>

0.01 g of Megafac [registered trademark] R-30 (manufactured by DIC Corporation) as a surfactant was dissolved in 40.0 g (including 10.0 g of solid content) of the solution of the copolymer obtained in Synthesis Example 8. Then, it filtered with a polyethylene fine filter with a pore diameter of 0.10 micrometer, and prepared the fat composition for microlens formation.

<Comparative example 1>

0.01 g of Megafac [registered trademark] R-30 (manufactured by DIC (stock)) as a surfactant was dissolved in 40.0 g (including 10.0 g of solid content) of the solution of the copolymer obtained in Synthesis Example 9. Then, it filtered with a polyethylene fine filter with a pore diameter of 0.10 micrometer, and prepared the fat composition for microlens formation.

<Comparative example 2>

0.01 g of Megafac [registered trademark] R-30 (manufactured by DIC Corporation) as a surfactant was dissolved in 40.0 g (including 10.0 g of a solid content) of the solution of the copolymer obtained in Synthesis Example 10. Then, it filtered with a polyethylene fine filter with a pore diameter of 0.10 micrometer, and prepared the fat composition for microlens formation.

<Comparative example 3>

0.01 g of Megafac [registered trademark] R-30 (manufactured by DIC (KK)) as a surfactant was dissolved in 40.0 g (including 10.0 g of solid content) of the solution of the copolymer obtained in Synthesis Example 11. Then, it filtered with a polyethylene fine filter with a pore diameter of 0.10 micrometer, and prepared the fat composition for microlens formation.

<Comparative Example 4>

0.01 g of Megafac [registered trademark] R-30 (manufactured by DIC Corporation) as a surfactant was dissolved in 40.0 g (including 10.0 g of a solid content) of the solution of the copolymer obtained in Synthesis Example 12. Then, use a pore size of 0.10 μm It is filtered with a polyethylene fine filter to prepare a lipid composition for microlens formation.

<Comparative example 5>

0.01 g of Megafac [registered trademark] R-30 (manufactured by DIC Corporation) as a surfactant was dissolved in 40.0 g (including 10.0 g of a solid content) of the solution of the copolymer obtained in Synthesis Example 13. Then, it filtered with a polyethylene fine filter with a pore diameter of 0.10 micrometer, and prepared the fat composition for microlens formation.

[Solvent resistance test]

The microlens-forming resin compositions prepared in Examples 1 to 5, Reference Examples 1 to 3, and Comparative Examples 1 to 5 were each coated on a silicon wafer using a spin coater, and heated. The plate was baked at 100 ° C. for 1 minute, and then baked at 230 ° C. for 10 minutes to form a film having a film thickness of 2 μm. For these films, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, butyl acetate, methyl 3-methoxypropionate, acetone, methyl isobutyl ketone, 2 -Heptane, 2-propanol, and a 2.38% by mass tetramethylammonium hydroxide (TMAH) aqueous solution were each immersed in a test at a temperature of 23 ° C for 5 minutes. Before and after immersion, the change in film thickness was measured. Even if one of the above immersion solvents had a film thickness increase or decrease of 5% or more before the immersion, it was evaluated as “×”. For all solvents, the film thickness increase or decrease was When it reached 5%, it was evaluated as "○" to evaluate the solvent resistance. The evaluation results are shown in Table 1.

[Transmittance measurement]

The microlens-forming resin compositions prepared in Examples 1 to 5, Reference Examples 1 to 3, and Comparative Examples 1 to 5 were each coated on a quartz substrate using a spin coater, and heated on a hot plate. The film was baked at 100 ° C. for 1 minute, and then baked at 230 ° C. for 10 minutes to form a film having a film thickness of 2 μm. For these films, an ultraviolet-visible spectrophotometer UV-2550 (manufactured by Shimadzu Corporation) was used, and the wavelength was changed by 2 nm each time in the range of 400 nm to 800 nm to measure the transmittance. After heating the film at 260 ° C for 5 minutes, the wavelength was changed by 2 nm each time in the range of 400 nm to 800 nm, and the transmittance was measured. Table 1 shows the minimum transmittance values measured in the range of wavelengths from 400nm to 800nm before and after heating at 260 ° C for 5 minutes.

[Measurement of dry etching speed]

The etchant and the etching gas for measuring the dry etching rate are as follows.

Etching machine: RIE-10NR (samco)

Etching gas: CF ₄

The microlens-forming resin compositions prepared in Examples 1 to 5, Reference Examples 1 to 3, and Comparative Examples 1 to 5 were each coated on a silicon wafer using a spin coater, and heated. The plate was baked at 100 ° C. for 1 minute, and then baked at 230 ° C. for 10 minutes to form a film having a film thickness of 2 μm. Using the above etching machine and etching gas, measure these Film dry etch rate. Similarly, a resist solution (THMR-iP1800 (manufactured by Tokyo Chemical Industry Co., Ltd.) was coated on a silicon wafer using a spin coater, and baked on a hot plate at 90 ° C for 1.5 minutes and 110 ° C. After baking for 1.5 minutes at 180 ° C. for 1 minute, a resist film with a thickness of 1 μm was formed, and the dry etching rate was measured. Then, from Example 1 to Example 5 and Reference Example 1 to Reference, the resist film was determined. The dry etching rate of the film obtained from the resin composition for microlens formation prepared in Example 3 and Comparative Examples 1 to Comparative Example 5. The evaluation results are shown in Table 1.

[Measurement of glass transition temperature (Tg)]

The microlens-forming resin compositions prepared in Examples 1 to 5, Reference Examples 1 to 3, and Comparative Examples 1 to 5 were each coated on a silicon wafer using a spin coater, and heated. The plate was baked at 100 ° C. for 1 minute, and then baked at 230 ° C. for 10 minutes to form a film having a film thickness of 2 μm. These films were peeled from the silicon wafer and measured using a differential scanning calorimeter DSC3100SR (manufactured by Mac Science). The evaluation results are shown in Table 1.

From the results in Table 1, the film formed from the resin composition for forming a microlens of the present invention has high solvent resistance, high transparency, and high heat resistance without coloring even after heating at 260 ° C. In addition, when the etch-back method faithfully transfers the lens pattern shape to the underlying microlens resin layer, the dry etching rate X of the resist film and the dry etching rate Y of the microlens resin layer need to be the same (X: Y = 1: 0.8 ~ 1.2, preferably X: Y = 1: 0.9 ~ 1.1), but the resin composition for forming a microlens of the present invention is a result satisfying this condition. From the viewpoint of the microlens forming process and the viewpoint of reliability as a permanent member, the Tg of the film formed of the microlens forming resin composition is preferably 200 ° C or higher, and more preferably a temperature exceeding 200 ° C. 200 ° C means that in the process of making microlenses from the film, resistance is formed on the film The temperature above the heating temperature required in the flux pattern is also the temperature above the reflow temperature of the resist pattern. The film formed from the resin composition for forming a microlens of the present invention satisfies the result that the Tg is 200 ° C or higher. On the other hand, it was found that the films formed from the resin compositions for microlens formation prepared in Comparative Examples 1 to 5 did not satisfy all the characteristics. The films formed from the resin compositions for microlens formation prepared in Reference Examples 1 to 3 had Tgs of 200 ° C.

Claims (6)

A resin composition for forming a microlens, characterized by containing a structural unit represented by the following formula (1), a structural unit represented by the formula (2), a structural unit represented by the formula (3-1) or (3-2) Copolymers and solvents with structural units represented by formula (4-1), (4-2) or (4-3),

(In the formula, X represents a cyclohexyl group or a phenyl group, Y represents a biphenyl group or a naphthyl group, R ⁰ independently represents a hydrogen atom or a methyl group, and R ² represents a linear, branched, or Cyclic alkyl, b represents 1 or 2). The resin composition for forming a microlens as claimed in item 1 of the patent scope, wherein the copolymer is a structural unit represented by the formula (3-1) and X is a structural unit represented by the formula (1). For example, the resin composition for forming a microlens according to item 1 or 2 of the patent application further contains a surfactant. The resin composition for forming a microlens as claimed in item 1 or 2 of the patent application, wherein the weight average molecular weight of the aforementioned copolymer is 1,000 to 100,000. A cured film whose characteristics are obtained from the resin composition for forming a microlens as described in any one of items 1 to 4 of the patent application. A method of manufacturing a microlens, which is characterized by the following stage: applying the resin composition for forming a microlens as described in any one of the patent application items 1 to 4 on a color filter layer and forming it by baking The stage of the resin layer, the stage of forming a resist pattern using the resist composition on the resin layer, the stage of reflowing the resist pattern to form a lens pattern, and using the lens pattern as an etching mask , Etching back the stage of the aforementioned resin layer.