JP7311846B2 - Non-photosensitive resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a non-photosensitive resin composition, and a cured film, a protective film, a planarizing film and a microlens formed from the non-photosensitive resin composition. The non-photosensitive resin composition of the present invention is a composition that does not contain a photosensitive agent such as a quinonediazide compound, and the copolymer contained in the non-photosensitive resin composition of the present invention is a compound having a protected carboxy group. and thermally crosslinked to form a cured film.

Electronic devices such as liquid crystal displays and CCD/CMOS image sensors are exposed to chemical solutions such as acid or alkaline solutions and solvents in the manufacturing process, as well as processes exposed to high temperatures such as sputtering, dry etching, and solder reflow. is done. In order to prevent the element from being deteriorated or damaged by such treatment, a cured film resistant to such treatment is formed on the element as a protective film. Such a protective film is required to have chemical resistance, high transparency, heat resistance, and the like.

When forming the cured film on a surface with unevenness such as a color filter, a cured film with high planarization properties is required from the viewpoint of ensuring process margins in subsequent steps and ensuring uniformity of device characteristics. Is required. Further, a microlens is also produced from such a cured film.

An etch-back method is known as one of the methods of manufacturing microlenses for CCD/CMOS image sensors (Patent Documents 1 and 2). That is, a resist pattern is formed on a microlens resin film formed on a color filter, and the resist pattern is reflowed by heat treatment to form a lens pattern. Using the lens pattern formed by reflowing the resist pattern as an etching mask, the microlens resin film under the lens pattern is etched back, and the shape of the lens pattern is transferred to the microlens resin film, thereby forming the microlens. make.

For example, Patent Documents 3 to 5 disclose resin compositions used for producing microlenses. However, all of them are photosensitive (radiation-sensitive) resin compositions, and cannot be said to be suitable materials for forming microlenses by the above etch-back method.

JP-A-1-10666 JP-A-6-112459 JP 2006-251464 A JP 2007-033518 A JP 2007-171572 A

The present invention was made based on the above circumstances, and an object of the present invention is to provide a resin composition capable of forming a cured film having excellent chemical resistance, heat resistance, transparency and flattening properties. be. Another object of the present invention is to provide a microlens with excellent chemical resistance and transparency.

（式（１）、式（２）及び式（３）中、Ｒ^０はそれぞれ独立に水素原子又はメチル基を表し、Ｙは芳香族炭化水素基を表し、該芳香族炭化水素基は、水素原子の一部又は全てがアルキル基、アルコキシ基、シアノ基又はハロゲン原子で置換されていてもよく、Ｒ^１は下記式（Ｉ）、式（ＩＩ）又は式（ＩＩＩ）で表される２価の有機基を表し、Ｒ^１が下記式（Ｉ）で表される２価の有機基を表す場合、前記式（Ｉ）中のカルボニル基は上記式（２）で表される構造単位の主鎖と結合し、Ｒ^２はエポキシ基を有する有機基を表し、Ｒ^３はアルキル基を表す。）

（式中、ｃは０乃至３の整数を表し、ｄは１乃至３の整数を表し、ｅはそれぞれ独立に２乃至６の整数を表す。）The present inventors have completed the present invention as a result of earnest studies to solve the above problems. That is, the present invention provides a copolymer having structural units represented by the following formulas (1) and (2), and 5% by mass to 90% by mass of the following formula (3) with respect to 100% by mass of the copolymer. ) and a non-photosensitive resin composition containing a solvent.

(In formula (1), formula (2) and formula (3), R ⁰ each independently represents a hydrogen atom or a methyl group, Y represents an aromatic hydrocarbon group, and the aromatic hydrocarbon group is hydrogen Some or all of the atoms may be substituted with an alkyl group, an alkoxy group, a cyano group or a halogen atom, and R ¹ is a divalent group represented by the following formula (I), formula (II) or formula (III) When R ¹ represents a divalent organic group represented by the following formula (I), the carbonyl group in the formula (I) is the main structural unit represented by the formula (2) chain, ^R2 represents an organic group with an epoxy group, and ^R3 represents an alkyl group.)

(Wherein, c represents an integer of 0 to 3, d represents an integer of 1 to 3, and e each independently represents an integer of 2 to 6.)

（式中、Ｒ^０はそれぞれ独立に水素原子又はメチル基を表し、Ｒ^１はそれぞれ独立に前記式（Ｉ）、式（ＩＩ）又は式（ＩＩＩ）で表される２価の有機基を表す。）The structural unit represented by the formula (2) is, for example, a structural unit represented by the following formula (2-1) or (2-2).

(wherein R ⁰ each independently represents a hydrogen atom or a methyl group, and R ¹ each independently represents a divalent organic group represented by formula (I), formula (II) or formula (III) .)

The weight average molecular weight of the copolymer is, for example, 1,000 to 100,000.

In formula (3), R ³ represents, for example, an alkyl group having 1 to 4 carbon atoms.

The non-photosensitive resin composition of the present invention can further contain a surfactant. The non-photosensitive resin composition of the present invention may contain no additives other than the surfactant.

The non-photosensitive resin composition of the present invention is, for example, a protective film-forming resin composition, a flattening film-forming resin composition, or a microlens-forming resin composition. The present invention is also a cured film obtained from the non-photosensitive resin composition. Further, the present invention is a protective film, a planarizing film, or a microlens produced from the non-photosensitive resin composition. The microlens is produced by the etch-back method described above. That is, a step of applying the non-photosensitive resin composition on a substrate and baking it at a temperature of 80 ° C. to 200 ° C. to form a cured film, forming a resist pattern on the cured film, and heating the resist. A microlens is produced by a step of reflowing a pattern to form a lens pattern, and a step of etching back the cured film using the lens pattern as a mask to transfer the shape of the lens pattern to the cured film.

The cured film is formed, for example, by baking at a temperature of 80° C. to 150° C. to evaporate the solvent from the non-photosensitive resin composition, followed by baking at a temperature of 160° C. to 200° C. The base material is, for example, a substrate on which a color filter is formed.

A cured film formed from the non-photosensitive resin composition of the present invention has excellent chemical resistance, heat resistance, transparency and flatness. As a result, the cured film is exposed to chemicals such as acid or alkaline solutions, solvents, etc., and is exposed to high temperatures such as sputtering, dry etching, solder reflow, etc. in the formation process or the formation process of peripheral devices such as wiring. The likelihood of device degradation or damage when exposed processing is performed can be significantly reduced. In the case of forming a protective film, planarizing film or microlens from the non-photosensitive resin composition of the present invention and applying a resist thereon, and in the case of performing the electrode/wiring forming step, mixing with the resist is required. problems, and deformation and peeling of protective films, planarizing films or microlenses due to chemicals can also be significantly reduced. Furthermore, since the non-photosensitive resin composition of the present invention contains a compound having a protected carboxy group, it has excellent storage stability at room temperature. By using the non-photosensitive resin composition of the present invention, a protective film, a planarizing film or a microlens can be formed at a temperature of 80°C to 200°C. Moreover, the non-photosensitive resin composition of the present invention does not require additives other than surfactants. Therefore, the non-photosensitive resin composition of the present invention, which does not contain a compound having an unprotected carboxyl group, does not lose storage stability, and bleeds such that the additive floats on the surface of the cured film during baking to form the cured film. No out occurs, and no bleeding of the additive occurs when the formed cured film comes into contact with the solvent. Therefore, the non-photosensitive resin composition of the present invention is suitable as a material for forming protective films, flattening films and microlenses.

FIG. 1 is a schematic diagram showing a cured film formed by coating the non-photosensitive resin composition of the present invention on a stepped substrate and baking it.

The present invention is a non-photosensitive resin composition containing a copolymer, a compound having a protected carboxyl group and a solvent. Details of each component contained in the non-photosensitive resin composition of the present invention are described below. The solid content of the non-photosensitive resin composition of the present invention after removing the solvent is usually 1% by mass to 50% by mass.

<Copolymer>
The copolymer contained in the non-photosensitive resin composition of the present invention is a copolymer having structural units represented by the formulas (1) and (2).

In formula (1), specific examples of the aromatic hydrocarbon group include a phenyl group, a biphenylyl group, and a naphthyl group. Specific examples of the compound (monomer) forming the structural unit represented by formula (1) include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-tert- Butylstyrene, 4-methoxystyrene, 4-cyanostyrene, 4-fluorostyrene, 4-chlorostyrene, 4-bromostyrene, 4-vinylbiphenyl, 1-vinylnaphthalene and 2-vinylnaphthalene. These compounds may be used individually by 1 type, or may be used in combination of 2 or more type.

The structural unit represented by the formula (2) is a structural unit represented by the formula (2-1) or formula (2-2), and the formula (2-1) or formula (2-2) Specific examples of compounds (monomers) forming structural units represented by the following formulas (2-1-1) to (2-1-8) and formulas (2-2-1) to (2 -2-8). In addition, these monomers may be used individually by 1 type, or may be used in combination of 2 or more type.

In the copolymer having the structural units represented by the formulas (1) and (2), the sum of the structural units represented by the formula (1) and the structural units represented by the formula (2) is 100 mol%. , the content of the structural unit represented by the formula (1) is 20 mol% to 95 mol%, preferably 50 mol% to 90 mol%, more preferably 65 mol% to 85 mol%, and the formula ( The content of the structural unit represented by 2) is 5 mol % to 80 mol %, preferably 10 mol % to 50 mol %, more preferably 15 mol % to 35 mol %.

The weight average molecular weight of the 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.

Further, the content of the copolymer in the non-photosensitive resin composition of the present invention is usually 1% by mass to 99% by mass based on the content in the solid content of the non-photosensitive resin composition, It is preferably 5% by mass to 95% by mass.

In the present invention, the method for obtaining the copolymer is not particularly limited. It can be obtained by polymerizing at a temperature of 50° C. to 120° C. in the presence of a solvent. The copolymer thus obtained is usually in the form of a solution dissolved in a solvent, and can be used in the non-photosensitive resin composition of the present invention without isolation in this state.

In addition, the copolymer solution obtained as described above is put into a poor solvent such as hexane, diethyl ether, methanol, or water, which is stirred, to reprecipitate the copolymer, and the resulting precipitate is After filtration and washing, the copolymer can be powdered by drying at room temperature or by heating under normal pressure or reduced pressure. By such an operation, the polymerization initiator and unreacted compounds 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, for example, in a solvent to be described later and used in the form of a solution.

<Solvent>
The solvent is not particularly limited as long as it dissolves the copolymer. Examples of such solvents 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, and propylene glycol monomethyl ether acetate. , propylene glycol monoethyl ether, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether, propylene glycol propyl ether acetate, propylene glycol monobutyl ether, propylene glycol monobutyl ether acetate, toluene, xylene, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2 -ethyl hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutanoate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, 3 -ethyl ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl acetate, butyl acetate, ethyl lactate, butyl lactate, 2-heptanone, γ-butyrolactone. These solvents may be used singly or in combination of two or more.

Among these solvents, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and propylene glycol are preferred from the viewpoint of improving the leveling properties of the coating film formed by coating the non-photosensitive resin composition of the present invention on a substrate. Monoethyl ether, propylene glycol monopropyl ether, 2-heptanone, ethyl lactate, butyl lactate, cyclopentanone and cyclohexanone are preferred.

<Compound Having Protected Carboxy Group>
The non-photosensitive resin composition of the present invention contains a compound having a protected carboxyl group, which is excellent in terms of storage stability, for the purpose of forming a cured film. The content thereof is 5% to 90% by mass, preferably 15% to 70% by mass, based on 100% by mass of the copolymer contained in the non-photosensitive resin composition. If the content of the compound having a protected carboxyl group is less than 5% by mass, the resulting film may not be sufficiently cured and may not have chemical resistance. Deprotected protective groups may cause defects such as voids during baking for film formation.

Examples of the compound having a protected carboxy group include compounds represented by the above formula (3) having three carboxy groups protected by alkyl vinyl ether in the molecule. The compound represented by the formula (3) is not particularly limited as long as the alkyl vinyl ether dissociates and volatilizes when the non-photosensitive resin composition coated on the substrate is baked. . In the compound represented by the formula (3), R ³ is an alkyl group having 1 to 4 carbon atoms (methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, isobutyl more preferred are the compounds representing the group (group, tert-butyl group).

Examples of commercially available products of the compound represented by formula (3) include the following products. Nofcure (registered trademark) TN-1, TN-4, TN-5 (manufactured by NOF Corporation).

<Surfactant>
Moreover, the non-photosensitive 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; polyoxyethylene octylphenyl ether; Polyoxyethylene alkylaryl ethers such as ethylene nonylphenyl ether, polyoxyethylene/polyoxypropylene block copolymers, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, sorbitan Sorbitan fatty acid esters such as tristearate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tristearate, etc. Nonionic surfactants such as polyoxyethylene sorbitan fatty acid esters, F-top [registered trademark] EF301, EF303, EF352 (manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.), Megafac [registered trademark] F-171 , F-173, R-30, R-40, R-40-LM (manufactured by DIC Corporation), Florard FC430, FC431 (manufactured by Sumitomo 3M), Asahi Guard [Registered Trademark] AG710, Surflon [Registered Trademark] S-382, SC101, SC102, SC103, SC104, SC105, SC106 (manufactured by AGC Inc.), FTX-206D, FTX-212D, FTX- 218, FTX-220D, FTX-230D, FTX-240D, FTX-212P, FTX-220P, FTX-228P, FTX-240G, etc. Ftergent series (manufactured by Neos Co., Ltd.) and other fluorine-based surfactants, organo Siloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.) can be mentioned. These surfactants may be used alone or in combination of two or more.

Further, when the surfactant is used, the content of the surfactant in the non-photosensitive resin composition of the present invention is 0 based on the content in the solid content of the non-photosensitive resin composition. 0001% to 3% by mass, preferably 0.001% to 1% by mass, more preferably 0.01% to 0.5% by mass.

The non-photosensitive resin composition of the present invention does not need to contain a curing agent other than the compound having a protected carboxyl group. In addition, the non-photosensitive resin composition of the present invention does not need to contain additives such as curing aids, ultraviolet absorbers, sensitizers, plasticizers, antioxidants and adhesion aids.

<Method for preparing non-photosensitive resin composition>
The method for preparing the non-photosensitive resin composition of the present invention is not particularly limited. For example, a copolymer having structural units represented by the formulas (1) and (2), and A method of dissolving the represented compound in a solvent to form a uniform solution can be mentioned.

<Method for preparing cured film, protective film and flattening film>
A method for producing a cured film, a protective film and a planarizing film using the non-photosensitive resin composition of the present invention will be described. The composition of the present invention is applied onto a substrate (for example, a semiconductor substrate, a glass substrate, a quartz substrate, a silicon wafer, and substrates having various metal films or color filters formed thereon) by an appropriate coating method using a spinner, coater, or the like. After applying the non-photosensitive resin composition, it is cured by baking using a heating means such as a hot plate or an oven to prepare a cured film, a protective film, or a planarizing film.

Baking conditions are appropriately selected from a baking temperature of 80° C. to 260° C., preferably 80° C. to 200° C., and a baking time of 0.3 minutes to 60 minutes. It is preferable to perform baking in two or more steps because a flat film can be obtained. When baking is performed in two or more steps, the first baking is performed to evaporate the solvent from the non-photosensitive resin composition applied on the substrate. The thickness of the film formed from the non-photosensitive resin composition of the invention is, for example, 0.001 μm to 100 μm, preferably 0.01 μm to 10 μm.

<Method for producing microlens>
A method for producing a microlens using the non-photosensitive resin composition of the present invention will be described. The composition of the present invention is applied onto a substrate (for example, a semiconductor substrate, a glass substrate, a quartz substrate, a silicon wafer, and substrates having various metal films or color filters formed thereon) by an appropriate coating method using a spinner, coater, or the like. After applying the non-photosensitive resin composition, it is baked and cured using a heating means such as a hot plate or an oven to prepare a cured film.

Baking conditions are appropriately selected from a baking temperature of 80° C. to 260° C., preferably 80° C. to 200° C., and a baking time of 0.3 minutes to 60 minutes. It is preferable to perform baking in two or more steps because a flat film can be obtained. When baking is performed in two or more steps, the first baking is performed to evaporate the solvent from the non-photosensitive resin composition applied on the substrate. The thickness of the cured film formed from the non-photosensitive resin composition of the present invention is, for example, 0.1 μm to 100 μm, preferably 0.5 μm to 10 μm.

After that, a resist is applied on the prepared cured film, exposed through a predetermined mask, post-exposure baking (PEB) is performed as necessary, alkali development, rinsing, and drying are performed to obtain a predetermined resist pattern. to form For exposure, for example, g-line, i-line, KrF excimer laser, ArF excimer laser can be used. Then, the resist pattern is reflowed by heat treatment to form a lens pattern. Using this lens pattern as an etching mask, the underlying cured film is etched back, and the shape of the lens pattern is transferred to the cured film to form a microlens.

EXAMPLES The present invention will be described in more detail below based on Examples and Comparative Examples, but the present invention is not limited to these Examples.
[Measurement of Weight Average Molecular Weight of Copolymers Obtained in Synthesis Examples Below]
Apparatus: GPC system manufactured by JASCO Corporation Column: Shodex (registered trademark) KF-804L and KF-803L
Column oven: 40°C
Flow rate: 1 mL/min Eluent: Tetrahydrofuran

[Synthesis of copolymer]
<Synthesis Example 1>
10.2 g of the monomer represented by the formula (2-1-3), 25.0 g of styrene and 0.77 g of 2,2′-azobisisobutyronitrile were dissolved in 53.9 g of propylene glycol monomethyl ether acetate. After that, this solution was added dropwise over 4 hours into a flask in which 12.8 g of propylene glycol monomethyl ether acetate was kept at 70°C. After completion of the dropwise addition, reaction was continued for 18 hours to obtain a copolymer solution (solid concentration: 35% by mass). The weight average molecular weight Mw of the resulting copolymer was 30,000 (converted to polystyrene).

<Synthesis Example 2>
9.0 g of the monomer represented by the formula (2-1-3), 25.0 g of 4-methylstyrene and 0.68 g of 2,2′-azobisisobutyronitrile were added to 52.0 g of propylene glycol monomethyl ether acetate. After dissolution, this solution was added dropwise over 4 hours into a flask in which 12.4 g of propylene glycol monomethyl ether acetate was maintained at 70°C. After completion of the dropwise addition, reaction was continued for 18 hours to obtain a copolymer solution (solid concentration: 35% by mass). The weight average molecular weight Mw of the resulting copolymer was 22,000 (converted to polystyrene).

<Synthesis Example 3>
6.3 g of the monomer represented by the above formula (2-1-3), 18.0 g of styrene, 8.3 g of 1-n-butoxyethyl methacrylate and 1.1 g of 2,2′-azobisisobutyronitrile were added to propylene. After dissolving in 50.5 g of glycol monomethyl ether acetate, this solution was added dropwise over 4 hours into a flask in which 12.0 g of propylene glycol monomethyl ether acetate was maintained at 70°C. After completion of the dropwise addition, reaction was continued for 18 hours to obtain a copolymer solution (solid concentration: 35% by mass). The weight average molecular weight Mw of the resulting copolymer was 15,000 (converted to polystyrene).

<Synthesis Example 4>
19.9 g of the monomer represented by the above formula (2-1-3), 38.0 g of styrene, 10.0 g of 4-hydroxyphenyl methacrylate and 2.3 g of 2,2′-azobisisobutyronitrile were mixed with propylene glycol monomethyl After dissolving in 105 g of ether acetate, this solution was added dropwise over 4 hours into a flask in which 25.1 g of propylene glycol monomethyl ether acetate was maintained at 70°C. After completion of the dropwise addition, reaction was continued for 18 hours to obtain a copolymer solution (solid concentration: 35% by mass). The weight average molecular weight Mw of the resulting copolymer was 22,000 (converted to polystyrene).

[Preparation of non-photosensitive resin composition]
<Example 1>
50.0 g of the solution of the copolymer obtained in Synthesis Example 1, Nofcure (registered trademark) TN-1 (PGMEA solution with a solid content concentration of 60% by mass) as the compound represented by the formula (3) (NOF ( (manufactured by DIC Corporation) and 0.01 g of Megafac (registered trademark) R-30 (manufactured by DIC Corporation) as a surfactant were dissolved in 29.5 g of propylene glycol monomethyl ether acetate to prepare a solution. Thereafter, the mixture was filtered using a polyethylene microfilter having a pore size of 0.10 μm to prepare a non-photosensitive resin composition.

<Example 2>
50.0 g of the copolymer solution obtained in Synthesis Example 2, Nofcure (registered trademark) TN-1 (PGMEA solution with a solid content concentration of 60% by mass) as the compound represented by the formula (3) (NOF ( (manufactured by DIC Corporation) and 0.01 g of Megafac (registered trademark) R-30 (manufactured by DIC Corporation) as a surfactant were dissolved in 28.4 g of propylene glycol monomethyl ether acetate to prepare a solution. Thereafter, the mixture was filtered using a polyethylene microfilter having a pore size of 0.10 μm to prepare a non-photosensitive resin composition.

<Comparative Example 1>
50.0 g of the copolymer solution obtained in Synthesis Example 3, 0.01 g of Megafac R-30 (manufactured by DIC Corporation) as a surfactant, and 17.3 g of propylene glycol monomethyl ether acetate and 16.8 g of propylene glycol monomethyl ether to form a solution. Thereafter, the mixture was filtered using a polyethylene microfilter having a pore size of 0.10 μm to prepare a non-photosensitive resin composition. This comparative example does not use the compound represented by the formula (3).

<Comparative Example 2>
50.0 g of the copolymer solution obtained in Synthesis Example 4, 2.2 g of tris(4-hydroxyphenyl)methane as a curing agent, and Megafac (registered trademark) R-30 (manufactured by DIC Corporation) as a surfactant. ) was dissolved in 6.8 g of propylene glycol monomethyl ether acetate and 16.8 g of propylene glycol monomethyl ether to form a solution. Thereafter, the mixture was filtered using a polyethylene microfilter having a pore size of 0.10 μm to prepare a non-photosensitive resin composition. The curing agent used in this comparative example does not correspond to the compound represented by the formula (3).

[Chemical resistance test]
The non-photosensitive resin compositions prepared in Examples 1 and 2, and Comparative Examples 1 and 2 were each applied onto a silicon wafer using a spin coater, placed on a hot plate at 100°C for 1 minute, Further, baking was performed at 180° C. for 5 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, cyclohexanone, γ-butyrolactone, 2-propanol, 2-heptanone and tetramethylammonium hydroxide (TMAH) at a concentration of 2.38 wt. A test was conducted by immersing the sample in an aqueous solution at a temperature of 23°C for 5 minutes. The film thickness was measured before and after immersion, and the change in film thickness before and after immersion was calculated. If even one of the solvents in which the film was immersed had a film thickness change of 5% or more compared to the film thickness before immersion, the film thickness was "x", and the film thickness change was less than 5% for all solvents. In that case, the chemical resistance was evaluated as “○”. Table 1 shows the evaluation results.

[Transmittance measurement]
Each of the non-photosensitive resin compositions prepared in Examples 1 and 2 and Comparative Examples 1 and 2 was applied onto a quartz substrate using a spin coater, placed on a hot plate at 100°C for 1 minute, Further, baking was performed at 180° C. for 5 minutes to form a film having a thickness of 2 μm. The transmittance of these films was measured using an ultraviolet-visible spectrophotometer UV-2550 (manufactured by Shimadzu Corporation) while changing the wavelength by 2 nm in the wavelength range of 400 nm to 800 nm. Table 1 shows the minimum transmittance values measured in the wavelength range of 400 nm to 800 nm.

[Measurement of cross-linking reaction rate]
The non-photosensitive resin compositions prepared in Examples 1 and 2 and Comparative Examples 1 and 2 were each applied onto a quartz substrate using a spin coater and baked on a hot plate at 100°C for 1 minute. was performed to form a film having a thickness of 2 μm. Infrared absorption spectra of these films were measured using a Fourier transform infrared spectrophotometer Nicolet 6700 (manufactured by Thermo Fisher Scientific Co., Ltd.). Further, this film was baked at 180° C. for 5 minutes, and the infrared absorption spectrum of the obtained film was measured again. Table 1 shows the cross-linking reaction rate calculated from the peak intensity at 906 cm ⁻¹ . The cross-linking reaction rate is defined as 0% reaction rate and 100% reaction rate at 906 cm ^-1 of the film formed by baking at 100 ° C. for 1 minute. It was calculated from the peak intensity at 906 cm ^-1 of the film obtained by baking for 5 minutes.

[Level difference flatness]
The non-photosensitive resin compositions prepared in Examples 1 and 2 were each applied onto a stepped substrate having a height of 0.5 μm, a line width of 10 μm, and a line-to-line space of 10 μm using a spin coater, and placed on a hot plate. It was baked at 100° C. for 1 minute and further at 180° C. for 5 minutes to form a film with a thickness of 2 μm. From h1 (step of stepped substrate) and h2 (film thickness difference of cured film) shown in FIG. Table 1 shows the evaluation results.

[Measurement of dry etching rate]
The etcher and etching gas used for measuring the dry etching rate are as follows.
Etcher: RIE-10NR (manufactured by Samco Corporation)
Etching gas: _CF4

Each of the non-photosensitive resin compositions prepared in Examples 1 and 2 was applied onto a silicon wafer using a spin coater, and baked on a hot plate at 100°C for 1 minute and then at 180°C for 5 minutes. , a film having a thickness of 2 μm was formed. The dry etching rates of these films were measured using the above etcher and etching gas. Similarly, a resist solution (THMR-iP1800 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied onto a silicon wafer using a spin coater and baked on a hot plate at 90° C. for 1.5 minutes to give a film thickness of 1 μm. A resist film was formed and the dry etching rate was measured, and the dry etching rate ratio of the film obtained from the non-photosensitive resin composition prepared in Examples 1 and 2 to the resist film was determined. Table 1 shows the evaluation results.

From the results of Table 1, the film formed from the non-photosensitive resin composition of the present invention is a cured film having high chemical resistance, high transparency, and excellent curability with a crosslinking reaction rate of 70% or more. there were. Incidentally, the higher the cross-linking reaction rate, the better. In addition, the film formed from the non-photosensitive resin composition of the present invention had a level difference flattening property with a flattening rate of 70% or more. Furthermore, in the fabrication of microlenses by the etch-back method, when the shape of the lens pattern is faithfully transferred to the resin film under the lens pattern, the dry etching rate X of the resist film and the dryness of the resin film under the lens pattern are determined. Etching rate Y is required to be equivalent (X: Y = 1: 0.8 to 1.2), and the film formed from the non-photosensitive resin composition of the present invention satisfies this. rice field. On the other hand, the films formed from the non-photosensitive resin compositions prepared in Comparative Examples 1 and 2 had insufficient cross-linking reaction rates compared to the films formed from the non-photosensitive resin composition of the present invention. , and it is highly likely that the film characteristics will change due to the subsequent process of exposure to high temperature, and it is not suitable for protective films, flattening films, and microlenses.

1: stepped substrate 2: cured film 3: line width 4: space between lines h1: stepped substrate h2: film thickness difference of cured film

Claims (11)

A copolymer having structural units represented by the following formulas (1) and (2), and a compound represented by the following formula (3) in an amount of 5% to 90% by mass based on 100% by mass of the copolymer. and a non-photosensitive resin composition for microlens production containing a solvent.

(In formula (1), formula (2) and formula (3), R ⁰ each independently represents a hydrogen atom or a methyl group, Y represents an aromatic hydrocarbon group, and the aromatic hydrocarbon group is hydrogen Some or all of the atoms may be substituted with an alkyl group, an alkoxy group, a cyano group or a halogen atom, and R ¹ is a divalent group represented by the following formula (I), formula (II) or formula (III) When R ¹ represents a divalent organic group represented by the following formula (I), the carbonyl group in the formula (I) is the main structural unit represented by the formula (2) linked to the chain, ^R2 represents an organic group having an epoxy group, and ^R3 each independently represents an alkyl group.)

(Wherein, c represents an integer of 0 to 3, d represents an integer of 1 to 3, and e each independently represents an integer of 2 to 6.) 2. The non-photosensitive resin composition for producing a microlens according to claim 1, wherein the structural unit represented by the formula (2) is a structural unit represented by the following formula (2-1) or (2-2). thing.

(Wherein, R ⁰ and R ¹ have the same definitions as in claim 1.) 3. The non-photosensitive resin composition for producing microlenses according to claim 1, wherein the copolymer has a weight average molecular weight of 1,000 to 100,000. 4. The non-photosensitive resin composition for producing microlenses according to any one of claims 1 to 3, wherein R3 in the formula ( ³ ) represents an alkyl group having 1 to 4 carbon atoms. 5. The non-photosensitive resin composition for producing microlenses according to any one of claims 1 to 4, further comprising a surfactant. 6. The non-photosensitive resin composition for producing microlenses according to claim 5, which does not contain additives other than the surfactant. A cured film obtained from the non-photosensitive resin composition for producing a microlens according to any one of claims 1 to 6. A microlens produced from the non-photosensitive resin composition for microlens production according to claim 1 . A step of applying the non-photosensitive resin composition for microlens fabrication according to any one of claims 1 to 6 onto a substrate and baking the composition at a temperature of 80°C to 200°C to form a cured film; forming a resist pattern on the cured film, reflowing the resist pattern by heat treatment to form a lens pattern, and etching back the cured film using the lens pattern as a mask to shape the lens pattern. A method for producing a microlens, including a step of transferring onto a cured film. The cured film is formed by baking the non-photosensitive resin composition for microlens fabrication at a temperature of 80° C. to 150° C. in order to evaporate the solvent, followed by baking at a temperature of 160° C. to 200° C. 10. The method of fabricating a microlens according to claim 9 . 11. The method of manufacturing a microlens according to claim 9 , wherein the base material is a substrate on which a color filter is formed.

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