TWI858130B - Non-photosensitive resin composition - Google Patents

Abstract

The subject of the present invention is to provide a thermosetting non-photosensitive resin composition. The non-photosensitive resin composition of the present invention comprises: a copolymer having structural units represented by the following formula (1) and formula (2), a compound represented by the following formula (3) and a solvent. (In formula (1), formula (2) and formula (3), R ⁰ independently represents a hydrogen atom or a methyl group, Y represents an aromatic hydrocarbon group, a part or all of the hydrogen atoms of the aromatic hydrocarbon group may be substituted by an alkyl group, an alkoxy group, a cyano group or a halogen atom, R ¹ represents a divalent organic group represented by the following formula (I), formula (II) or formula (III), when R ¹ is a divalent organic group represented by the following formula (I), the carbonyl group in the aforementioned formula (I) is bonded to the main chain of the structural unit represented by the aforementioned formula (2), R ² represents an organic group having an epoxide group, and R ³ represents an alkyl group) (wherein c represents an integer from 0 to 3, d represents an integer from 1 to 3, and e represents an integer from 2 to 6 respectively).

Description

Non-photosensitive resin composition

The present invention relates to a non-photosensitive resin composition, and a cured film, a protective film, a planarized film, and a microlens formed by 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 forms a cured film by thermal crosslinking with a compound having a protected carboxyl group.

Electronic devices such as LCDs and CCD/CMOS image sensors are subjected to the following treatments during their manufacturing process: exposure to acid or alkaline solutions, solvents, and other chemical solutions, or exposure to high-temperature treatments such as sputtering, dry etching, and solder reflow. In order to prevent the components from being degraded or damaged by such treatments, a hardened film resistant to such treatments is formed on the components as a protective film. Such protective films are required to have chemical resistance, high transparency, and heat resistance.

When the above-mentioned cured film is formed on a surface with unevenness such as a color filter, a cured film with high flattening properties is required from the viewpoint of ensuring process margin in subsequent steps and ensuring uniformity of device characteristics. In addition, microlenses can also be manufactured from such a cured film.

As one of the methods for manufacturing microlenses for CCD/CMOS image sensors, an etch back method is known (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. The lens pattern formed by reflowing the resist pattern is used as an etching mask, and the microlens resin film under the lens pattern is etched back to manufacture a microlens by transferring the shape of the lens pattern to the microlens resin film.

For example, Patent Documents 3 to 5 disclose a resin composition used for the production of 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-mentioned etching method. [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent Publication No. 1-10666 [Patent Document 2] Japanese Patent Publication No. 6-112459 [Patent Document 3] Japanese Patent Publication No. 2006-251464 [Patent Document 4] Japanese Patent Publication No. 2007-033518 [Patent Document 5] Japanese Patent Publication No. 2007-171572

[The problem that the invention wants to solve]

The present invention is an invention completed based on the above situation, and its purpose is to provide a resin composition that can form a cured film with excellent chemical resistance, heat resistance, transparency and flattening properties. In addition, another purpose of the present invention is to provide a microlens with excellent chemical resistance and transparency. [Means for solving the problem]

The inventors of the present invention have completed the present invention after in-depth research to solve the above-mentioned problems. That is, the present invention is a non-photosensitive resin composition, comprising: a copolymer having structural units represented by the following formulas (1) and (2), a compound represented by the following formula (3), and a solvent, wherein the compound represented by the formula (3) is 5% to 90% by weight relative to 100% by weight of the copolymer. (In formula (1), formula (2) and formula (3), R ⁰ independently represents a hydrogen atom or a methyl group, Y represents an aromatic hydrocarbon group, a part of or all of the hydrogen atoms of the aromatic hydrocarbon group may be substituted by an alkyl group, an alkoxy group, a cyano group or a halogen atom, R ¹ represents a divalent organic group represented by the following formula (I), formula (II) or formula (III), when R ¹ is a divalent organic group represented by the following formula (I), the carbonyl group in the aforementioned formula (I) is bonded to the main chain of the structural unit represented by the aforementioned formula (2), R ² represents an organic group having an epoxide group, and R ³ represents an alkyl group). (wherein c represents an integer from 0 to 3, d represents an integer from 1 to 3, and e represents an integer from 2 to 6 respectively).

The structural unit represented by the above formula (2) is, for example, a structural unit represented by the following formula (2-1) or formula (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 the aforementioned formula (I), formula (II) or formula (III)).

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

In the above 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 may further contain a surfactant. The non-photosensitive resin composition of the present invention may not contain additives other than the aforementioned surfactant.

The non-photosensitive resin composition of the present invention is, for example, a resin composition for forming a protective film, a resin composition for forming a planarized film, or a resin composition for making a microlens. The present invention is also a cured film obtained from the aforementioned non-photosensitive resin composition. Furthermore, the present invention is a protective film, a planarized film, or a microlens made from the aforementioned non-photosensitive resin composition. The aforementioned microlens is made by the aforementioned etching back method. That is, the microlens is manufactured by the following steps: The aforementioned non-photosensitive resin composition is coated on a substrate and baked at a temperature of 80°C to 200°C to form a cured film; A resist pattern is formed on the cured film, and the aforementioned resist pattern is reflowed by heat treatment to form a lens pattern; and The shape of the lens pattern is transferred to the cured film by using the lens pattern as a mask and etching back the aforementioned 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, and then baking at a temperature of 160°C to 200°C. The substrate is, for example, a substrate on which a color filter is formed. [Effect of the invention]

The cured film formed by the non-photosensitive resin composition of the present invention has excellent chemical resistance, heat resistance, transparency and planarization properties. Therefore, in the formation step or the formation step of peripheral devices such as wiring, even when exposed to a chemical solution such as an acid or alkaline solution or a solvent, or exposed to a high temperature treatment such as sputtering, dry etching, solder reflow, etc., the aforementioned cured film can significantly reduce the possibility of deterioration or damage of the device. In addition, when a protective film, a planarization film or a microlens is formed by the non-photosensitive resin composition of the present invention and a resist is applied thereon, and when an electrode/wiring formation step is performed, problems such as mixing with the resist and deformation and peeling of the protective film, the planarization film or the microlens caused by the chemical solution can be significantly reduced. Furthermore, since the non-photosensitive resin composition of the present invention contains a compound having a protected carboxyl group, the storage stability at room temperature is excellent. By using the non-photosensitive resin composition of the present invention, a protective film, a planarization film or a microlens can be formed at a temperature of 80°C to 200°C. In addition, 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 suffer from loss of storage stability, does not cause the additive to bleed out on the surface of the cured film during baking to form the cured film, and does not cause the additive to bleed out when the formed cured film contacts the solvent. Therefore, the non-photosensitive resin composition of the present invention is suitable as a material for forming a protective film, a planarizing film, and a microlens.

[Best Mode for Carrying Out the Invention]

The present invention is a non-photosensitive resin composition, comprising: a copolymer, a compound having a protected carboxyl group, and a solvent. The following describes the details of each component contained in the non-photosensitive resin composition of the present invention. The solid content after removing the solvent from the non-photosensitive resin composition of the present invention is generally 1 mass % to 50 mass %.

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

In the above formula (1), specific examples of the aromatic hydrocarbon group include phenyl, biphenyl, and naphthyl. Specific examples of the compound (monomer) forming the structural unit represented by the above 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 alone or in combination of two or more.

The structural unit represented by the aforementioned formula (2) is the structural unit represented by the aforementioned formula (2-1) or formula (2-2). As specific examples of the compound (monomer) forming the structural unit represented by the aforementioned formula (2-1) or formula (2-2), monomers represented by the following formulas (2-1-1) to (2-1-8) and (2-2-1) to (2-2-8) can be cited. In addition, these monomers can be used alone or in combination of two or more.

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

The weight average molecular weight of the copolymer is generally 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.

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

In the present invention, the method for obtaining the above-mentioned copolymer is not particularly limited, and is generally obtained by polymerizing the compounds (monomers) forming the structural units represented by the above-mentioned formula (1) and formula (2) 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 manner is generally in the form of a solution dissolved in the solvent, and can therefore be used in the non-photosensitive resin composition of the present invention in this state without isolation.

Furthermore, the copolymer can be made into powder by putting the solution of the copolymer obtained in the above manner into a stirred poor solvent such as hexane, diethyl ether, methanol, water, etc., re-precipitating the copolymer, filtering and washing the resulting precipitate, and then drying at room temperature or heating under normal pressure or reduced pressure. By such an operation, the polymerization initiator or unreacted compound coexisting with the copolymer can be removed. In the present invention, the copolymer powder can be used directly, or the powder can be redissolved in, for example, a solvent described later and used in the state of a solution.

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

From the viewpoint of improving the leveling property of the coating formed by coating the non-photosensitive resin composition of the present invention on a substrate, among the solvents, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether, propylene glycol monopropyl ether, 2-heptanone, ethyl lactate, butyl lactate, cyclopentanone and cyclohexanone are preferred.

<Compounds with protected carboxyl groups> For the purpose of forming a cured film, the non-photosensitive resin composition of the present invention contains a compound with protected carboxyl groups which is excellent in terms of storage stability. The content of the compound with protected carboxyl groups is 5% to 90% by mass, preferably 15% to 70% by mass, relative to 100% by mass of the copolymer contained in the non-photosensitive resin composition. When the content of the compound with protected carboxyl groups is less than 5% by mass, the cured film formed may not be sufficiently cured and may not have chemical resistance. When the content exceeds 90% by mass, during baking when the cured film is formed, there is a risk of defects such as voids due to the deprotection of the protective group.

As the aforementioned compound having a protected carboxyl group, there can be mentioned a compound represented by the aforementioned formula (3) having three carboxyl groups protected by an alkyl vinyl ether in the molecule. The compound represented by the aforementioned formula (3) is not particularly limited as long as the alkyl vinyl ether is dissociated and volatilized when the non-photosensitive resin composition coated on the substrate is baked. Among the compounds represented by the aforementioned formula (3), a compound in which R ³ represents an alkyl group having 1 to 4 carbon atoms (methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl) is particularly preferred.

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

<Surfactant> In addition, for the purpose of improving coating properties, the non-photosensitive resin composition of the present invention may also contain a surfactant. Examples of the aforementioned surfactant include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl aryl ethers such as polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene-polyoxypropylene block polymers, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, sorbitan Nonionic surfactants such as sorbitan fatty acid esters such as tristearate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tristearate, etc., F-Top [registered trademark] EF301, EF303, EF352 (all manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.), Megaface [registered trademark] F-171, F-173, R-30, R-40, R-40-LM (all manufactured by DIC Co., Ltd.), Fluorad FC430, FC431 (all manufactured by Sumitomo 3M Co., Ltd.), AashiGuard [registered trademark] AG710, Surflon [registered trademark] S-382, SC101, SC102, SC103, SC104, SC105, SC106 (AGC Co., Ltd.), FTX-206D, FTX-212D, FTX-218, FTX-220D, FTX-230D, FTX-240D, FTX-212P, FTX-220P, FTX-228P, FTX-240G and other Ftergent series (Neos Co., Ltd.), and organic silicone polymer KP341 (Shin-Etsu Chemical Co., Ltd.). These surfactants may be used alone or in combination of two or more.

When the surfactant is used, the content of the surfactant in the non-photosensitive resin composition of the present invention is 0.0001% by mass to 3% by mass, preferably 0.001% by mass to 1% by mass, and more preferably 0.01% by mass to 0.5% by mass, based on the content in the solid content of the non-photosensitive resin composition.

The non-photosensitive resin composition of the present invention may not contain a curing agent other than the compound having a protected carboxyl group. Furthermore, the non-photosensitive resin composition of the present invention may not contain additives such as a curing aid, an ultraviolet absorber, a sensitizer, a plasticizer, an antioxidant, and an adhesion aid.

<Method for preparing non-photosensitive resin composition> The method for preparing the non-photosensitive resin composition of the present invention is not particularly limited, and an example thereof is a method in which a copolymer having structural units represented by the aforementioned formula (1) and formula (2) and a compound represented by the aforementioned formula (3) are dissolved in a solvent to prepare a uniform solution.

<Method for producing cured film, protective film and planarized film> The method for producing a cured film, protective film and planarized film obtained by using the non-photosensitive resin composition of the present invention is described. The non-photosensitive resin composition of the present invention is applied to a substrate (e.g., a semiconductor substrate, a glass substrate, a quartz substrate, a silicon wafer, and a substrate having various metal films or color filters formed on the surface thereof) by an appropriate coating method such as a spinner or a coater, and then baked using a heating method such as a heating plate or an oven to cure the substrate, thereby producing a cured film, a protective film, or a planarized film.

The baking conditions can be 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. Since a flat film can be obtained, it is preferred that the baking be carried out in two or more stages. When the baking is carried out in two or more stages, the initial baking is carried out to evaporate the solvent from the non-photosensitive resin composition applied on the aforementioned substrate. In addition, the film thickness of the film formed by the non-photosensitive resin composition of the present invention is, for example, 0.001μm~100μm, preferably 0.01μm~10μm.

<Microlens production method> The following describes a method for producing a microlens using the non-photosensitive resin composition of the present invention. The non-photosensitive resin composition of the present invention is applied to a substrate (e.g., a semiconductor substrate, a glass substrate, a quartz substrate, a silicon wafer, and a substrate having various metal films or color filters formed on the surface thereof) by an appropriate coating method such as a spinner or a coating machine, and then is baked to cure using a heating method such as a heating plate or an oven to produce a cured film.

The baking conditions can be 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. Since a flat film can be obtained, it is preferred that the baking be carried out in two or more stages. When the baking is carried out in two or more stages, the initial baking is carried out to evaporate the solvent from the non-photosensitive resin composition applied on the aforementioned substrate. In addition, the film thickness of the cured film formed by the non-photosensitive resin composition of the present invention is, for example, 0.1μm to 100μm, preferably 0.5μm to 10μm.

Afterwards, a resist is applied on the prepared cured film, and exposure is performed through a specified mask, and post-exposure heating (PEB) is performed as required, and alkaline development, rinsing and drying are performed to form a specified resist pattern. Exposure can use, for example, g-line, i-line, KrF excimer laser, ArF excimer laser. Next, the resist pattern is reflowed by heat treatment to form a lens pattern. By using the lens pattern as an etching mask and etching back the underlying cured film, the shape of the lens pattern is transferred to the cured film to produce a microlens. [Example]

The present invention is 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 copolymer obtained in the following synthesis example] 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 above 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, and the solution was dripped into a flask containing 12.8 g of propylene glycol monomethyl ether acetate at 70°C for 4 hours. After the dripping was completed, the mixture was allowed to react for 18 hours to obtain a copolymer solution (solid content concentration 35% by mass). The weight average molecular weight Mw of the obtained copolymer was 30,000 (polystyrene conversion).

<Synthesis Example 2> 9.0 g of the monomer represented by the above formula (2-1-3), 25.0 g of 4-methylstyrene and 0.68 g of 2,2'-azobisisobutyronitrile were dissolved in 52.0 g of propylene glycol monomethyl ether acetate, and the solution was dripped into a flask containing 12.4 g of propylene glycol monomethyl ether acetate at 70°C for 4 hours. After the dripping was completed, the mixture was further reacted for 18 hours to obtain a copolymer solution (solid content concentration 35% by mass). The weight average molecular weight Mw of the obtained copolymer was 22,000 (polystyrene conversion).

<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 dissolved in 50.5 g of propylene glycol monomethyl ether acetate, and the solution was dripped into a flask containing 12.0 g of propylene glycol monomethyl ether acetate at 70°C for 4 hours. After the dripping was completed, the mixture was allowed to react for 18 hours to obtain a copolymer solution (solid content concentration 35% by mass). The weight average molecular weight Mw of the obtained copolymer was 15,000 (polystyrene conversion).

<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 dissolved in 105 g of propylene glycol monomethyl ether acetate, and the solution was dripped into a flask containing 25.1 g of propylene glycol monomethyl ether acetate at 70°C for 4 hours. After the dripping was completed, the mixture was further reacted for 18 hours to obtain a copolymer solution (solid content concentration 35% by mass). The weight average molecular weight Mw of the obtained copolymer was 22,000 (polystyrene conversion).

[Preparation of non-photosensitive resin composition] <Example 1> 50.0 g of the solution of the copolymer obtained in Synthesis Example 1, 9.3 g of Nofcure [registered trademark] TN-1 (60% by mass solid content PGMEA solution) (manufactured by NOF Corporation) as the compound represented by the above formula (3), and 0.01 g of Megaface [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 solution was filtered using a polyethylene microfilter with 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, 8.5 g of Nofcure [registered trademark] TN-1 (60% by mass solid content PGMEA solution) (manufactured by NOF Corporation) as the compound represented by the above formula (3), and 0.01 g of Megaface [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 solution 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 and 0.01 g of Megaface [registered trademark] R-30 (manufactured by DIC Corporation) as a surfactant were dissolved in 17.3 g of propylene glycol monomethyl ether acetate and 16.8 g of propylene glycol monomethyl ether to prepare a solution. Thereafter, the solution was filtered using a polyethylene microfilter having a pore size of 0.10 μm to prepare a non-photosensitive resin composition. The compound represented by the above formula (3) was not used in this comparative example.

<Comparative Example 2> 50.0 g of the copolymer solution obtained in Synthesis Example 4, 2.2 g of 3-(4-hydroxyphenyl)methane as a curing agent, and 0.01 g of Megaface [registered trademark] R-30 (manufactured by DIC Corporation) as a surfactant were dissolved in 6.8 g of propylene glycol monomethyl ether acetate and 16.8 g of propylene glycol monomethyl ether to prepare a solution. Thereafter, the solution was filtered using a polyethylene microfilter having a pore size of 0.10 μm to prepare a non-photosensitive resin composition. In this comparative example, the curing agent used was not equivalent to the compound represented by the aforementioned formula (3).

[Chemical resistance test] Using a rotary coater, the non-photosensitive resin compositions prepared in Example 1 and Example 2, and Comparative Examples 1 and Comparative Examples 2 were coated on a silicon wafer, respectively, and baked on a hot plate at 100°C for 1 minute, and then at 180°C for 5 minutes to form a film with a thickness of 2μm. For these films, an immersion test was performed at 23°C for 5 minutes in propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, cyclohexanone, γ-butyrolactone, 2-propanol, 2-heptanone, and a 2.38 mass% concentration of tetramethylammonium hydroxide (TMAH) aqueous solution. The film thickness was measured before and after immersion, and the change in film thickness before and after immersion was calculated. If the film thickness increased or decreased by 5% or more compared to the film thickness before immersion, even if it was one of the solvents used to immerse the film, it was marked as "×"; if the film thickness increased or decreased by less than 5% compared to all solvents, it was marked as "○" to evaluate the chemical resistance. The evaluation results are shown in Table 1.

[Transmittance measurement] Using a rotary coater, the non-photosensitive resin compositions prepared in Example 1 and Example 2, and Comparative Examples 1 and Comparative Examples 2 were coated on a quartz substrate, respectively, and baked on a hot plate at 100°C for 1 minute and then at 180°C for 5 minutes to form a film with 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 using an ultraviolet-visible spectrophotometer UV-2550 (manufactured by Shimadzu Corporation). The minimum transmittance values measured in the range of 400 nm to 800 nm are shown in Table 1.

[Crosslinking reaction rate measurement] Using a rotary coater, the non-photosensitive resin composition prepared in Example 1 and Example 2, and Comparative Example 1 and Comparative Example 2 were coated on a quartz substrate, respectively, and baked on a heating plate at 100°C for 1 minute to form a film with a thickness of 2 μm. For such films, the infrared absorption spectrum was measured using a Fourier transform infrared spectrophotometer Nicolet 6700 (manufactured by Thermo Scientific (Stock)). Furthermore, the film was baked at 180°C for 5 minutes, and the infrared absorption spectrum of the obtained film was measured again. The crosslinking reaction rate calculated based on the peak intensity at 906 cm ^-1 is shown in Table 1. The peak intensity at 906 cm ^-1 of the film formed by baking at 100°C for 1 minute was defined as a reaction rate of 0%, and a peak intensity of 0 was defined as a reaction rate of 100%. The crosslinking reaction rate was calculated from the peak intensity at 906 cm ^-1 of the film obtained by baking at 180°C for 5 minutes.

[High-low Flatness] Using a rotary coater, the non-photosensitive resin composition prepared in Example 1 and Example 2 was coated on a high-low substrate with a height of 0.5 μm, a line width of 10 μm, and a line spacing of 10 μm, respectively, and baked on a hot plate at 100°C for 1 minute and then at 180°C for 5 minutes to form a film with a thickness of 2 μm. The flattening rate was calculated from h1 (high-low substrate high-low substrate) and h2 (thickness difference of cured film) shown in Figure 1 using the "formula: (1-(h2/h1))×100". The evaluation results are shown in Table 1.

[Dry Etching Rate Measurement] The etching machine and etching gas used for dry etching rate measurement are as follows. Etching machine: RIE-10NR (manufactured by Samco) Etching gas: CF ₄

Using a spin coater, the non-photosensitive resin compositions prepared in Example 1 and Example 2 were coated on a silicon wafer, respectively, and baked on a hot plate at 100°C for 1 minute and then at 180°C for 5 minutes to form a film with a thickness of 2 μm. The dry etching rates of the films were measured using the aforementioned etching machine and etching gas. Similarly, a resist solution (THMR-iP1800 (manufactured by Tokyo Ohka Industry Co., Ltd.) was applied to a silicon wafer using a spin coater and baked on a hot plate at 90°C for 1.5 minutes to form a resist film with a thickness of 1 μm, and the dry etching rate was measured. In addition, the dry etching rate ratio of the film obtained by the non-photosensitive resin composition prepared in Examples 1 and 2 relative to the aforementioned resist was determined. The evaluation results are shown in Table 1.

According to the results in Table 1, the film formed by the non-photosensitive resin composition of the present invention has high chemical resistance and high transparency, and is a cured film with excellent curing property with a crosslinking reaction rate of 70% or more. In addition, the higher the value of the crosslinking reaction rate, the better. In addition, the film formed by the non-photosensitive resin composition of the present invention has a high-height flattening property with a flattening rate of 70% or more. Furthermore, in the production of microlenses by the back-etching method, when the shape of the lens pattern is faithfully transferred to the resin film of the lower layer of the lens pattern, the dry etching rate X of the resist film is required to be the same as the dry etching rate Y of the resin film of the lower layer of the lens pattern (X:Y=1:0.8~1.2). The film formed by the non-photosensitive resin composition of the present invention satisfies this result. On the other hand, the films formed by the non-photosensitive resin compositions prepared in Comparative Examples 1 and 2 have insufficient crosslinking reaction rates compared to the films formed by the non-photosensitive resin composition of the present invention, and are more likely to be deteriorated in film properties due to exposure to high temperature treatment in subsequent steps. Therefore, they are unsuitable for use as protective films, planarization films, and microlenses.

1: Height difference substrate 2: Cured film 3: Line width 4: Line interval h1: Height difference of height difference substrate h2: Thickness difference of cured film

[Fig. 1] Fig. 1 is a schematic diagram showing a cured film formed by coating the non-photosensitive resin composition of the present invention on a substrate with a height difference and baking the coating.

1: Height difference substrate

2: Hardening film

3: Line width

4: Line spacing

h1: height difference of the height difference substrate

h2: Thickness difference of hardened film

Claims (9)

A microlens is produced by using a non-photosensitive resin composition for microlens production, wherein the non-photosensitive resin composition for microlens production comprises: a copolymer having structural units represented by the following formulas (1) and (2), a compound represented by the following formula (3), and a solvent, wherein the compound represented by the formula (3) accounts for 5% to 90% by weight relative to 100% by weight of the copolymer.

(In formula (1), formula (2) and formula (3), R ⁰ independently represents a hydrogen atom or a methyl group, Y represents an aromatic hydrocarbon group, a part or all of the hydrogen atoms of the aromatic hydrocarbon group may be substituted by an alkyl group, an alkoxy group, a cyano group or a halogen atom, R ¹ represents a divalent organic group represented by the following formula (I), formula (II) or formula (III), when R ¹ is a divalent organic group represented by the following formula (I), the carbonyl group in the aforementioned formula (I) is bonded to the main chain of the structural unit represented by the aforementioned formula (2), R ² represents an organic group having an epoxide group, and R ³ independently represents an alkyl group)

(wherein c represents an integer from 0 to 3, d represents an integer from 1 to 3, and e represents an integer from 2 to 6 respectively). The microlens of claim 1, wherein the structural unit represented by the aforementioned formula (2) is a structural unit represented by the following formula (2-1) or formula (2-2),

(wherein, ^R0 and ^R1 have the same meaning as defined in claim 1). The microlens of claim 1 or claim 2, wherein the weight average molecular weight of the copolymer is 1,000 to 100,000. The microlens of claim 1 or claim 2, wherein ^R3 in the above formula (3) represents an alkyl group having 1 to 4 carbon atoms. As in the microlens of claim 1 or claim 2, wherein the microlens is made of a non-photosensitive resin composition and further contains a surfactant. As in claim 5, the microlens is made of a non-photosensitive resin composition that does not contain additives other than the surfactant. A method for manufacturing a microlens comprises the following steps: coating a non-photosensitive resin composition for the microlens on a substrate and baking the composition at a temperature of 80°C to 200°C to form a hardened film; forming a resist pattern on the hardened film, and reflowing the resist pattern by heat treatment to form a lens pattern; and using the lens pattern as a mask and etching back the resist pattern. The non-photosensitive resin composition for making the microlens comprises: a copolymer having structural units represented by the following formula (1) and formula (2), a compound represented by the following formula (3), and a solvent, wherein the compound represented by the following formula (3) accounts for 5% to 90% by weight relative to 100% by weight of the copolymer.

(In formula (1), formula (2) and formula (3), R ⁰ independently represents a hydrogen atom or a methyl group, Y represents an aromatic hydrocarbon group, a part or all of the hydrogen atoms of the aromatic hydrocarbon group may be substituted by an alkyl group, an alkoxy group, a cyano group or a halogen atom, R ¹ represents a divalent organic group represented by the following formula (I), formula (II) or formula (III), when R ¹ is a divalent organic group represented by the following formula (I), the carbonyl group in the aforementioned formula (I) is bonded to the main chain of the structural unit represented by the aforementioned formula (2), R ² represents an organic group having an epoxide group, and R ³ independently represents an alkyl group)

(wherein c represents an integer from 0 to 3, d represents an integer from 1 to 3, and e represents an integer from 2 to 6 respectively). As in claim 7, the method for manufacturing a microlens, wherein the hardened film is formed by baking at a temperature of 80°C to 150°C to evaporate the solvent from the non-photosensitive resin composition for manufacturing the microlens, and then baking at a temperature of 160°C to 200°C. A method for manufacturing a microlens as claimed in claim 7 or claim 8, wherein the substrate is a substrate having a color filter formed thereon.

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