JP7701678B2 - Positive-type photosensitive resin composition containing a specific copolymer - Google Patents

Description

The present invention relates to a positive-type photosensitive resin composition, a cured film obtained from the resin composition, a microlens, and a method for producing the same.

In imaging devices such as CCD image sensors and CMOS image sensors, or display devices such as liquid crystal displays and organic EL displays, tiny lenses called microlenses are often used to improve performance. For example, providing a microlens to the image sensor has the effect of improving the light collection rate and increasing the sensor sensitivity.

The etch-back method is known as one method for producing microlenses (see, for example, Patent Document 1). That is, a resin layer for microlenses is formed on a color filter, a positive resist is applied onto the resin layer, and a lens pattern is formed by exposing and developing a part of the resist and heating it as necessary. The lens pattern is used as an etching mask to perform etch-back, and the lens pattern shape is transferred to the resin layer for microlenses to produce the microlenses.

On the other hand, from the viewpoint of reducing manufacturing costs, a method has been proposed in which the positive resist is used as a microlens as it is. In this case, since it is necessary to have both the properties of a resist and the properties of a microlens, a photosensitive resin composition is required that is not only capable of positive patterning but also allows the microlens formed to have excellent transparency and chemical resistance. Here, the shape of the microlens varies depending on the design of the element, and various shapes such as a prism, a cylinder, a pyramid frustum, a cone frustum, and a spheroid may be required. When producing a spheroid-shaped microlens, a method is known in which a pattern such as a prism or pyramid frustum is formed and then reflowed (fluidized by heating; also called melt flow or thermal flow).

For example, Patent Document 2 proposes a photosensitive resin composition containing an alkali-soluble copolymer and a quinone diazide group-containing compound. By using this composition, a resin pattern can be formed by exposure and development, and then the phenolic hydroxyl group and the epoxy group can be crosslinked by heating to obtain a microlens.

However, in recent years, the use of devices with low heat resistance, such as organic devices and flexible devices, has led to an increasing demand for lower process temperatures. Accordingly, a positive-type photosensitive resin composition capable of producing microlenses with good performance even in low-temperature processes is desired. When producing a microlens with a spherical asymmetry, sufficient reflow is required even at low temperatures. A specific upper process temperature limit of 150°C is required, and particularly 130°C has been required recently. The photosensitive resin composition described in Patent Document 2 employs thermal curing of phenolic hydroxyl groups and epoxy groups, but this thermal curing reaction usually requires high-temperature conditions exceeding 150°C, and is therefore not suitable for low-temperature processes below 130°C.

Therefore, Patent Document 3 proposes a radiation-sensitive resin composition that contains an alkali-soluble copolymer, a 1,2-quinone diazide compound, and a compound that generates an acid upon exposure to radiation. By using this composition, a resin pattern is formed by exposure and development, and then a strong acid is generated inside the resin pattern by exposure again, allowing cationic polymerization to proceed, making it possible to lower the process temperature. However, the monomer that forms the alkali-soluble copolymer used in this composition contains a carboxylic acid or a carboxylic acid anhydride, and there is a risk of residue being generated when the copolymer is patterned. If part of the resin remains in the space between patterns, this has a significant adverse effect on the characteristics of the element, so a photosensitive resin composition that allows positive patterning without residue is required.

In addition, Patent Document 4 proposes a radiation-sensitive resin composition containing an alkali-soluble polymer, a quinone diazide compound, and a compound that generates an acid having a pKa of 4.0 or less. However, the alkali-soluble polymer does not mention long-term reliability (HTS test, THS test, xenon arc test, etc.) other than storage stability, and its characteristics are unknown. The organic devices and flexible devices must have reliability that can withstand practical use, and therefore there is a demand for a photosensitive resin composition that does not deteriorate even after long-term reliability tests such as HTS test (high temperature test), THS test (high temperature and high humidity test), and xenon arc test are performed, and that can produce microlenses with good performance.

Japanese Unexamined Patent Publication No. 1-10666 JP 2007-33518 A JP 2009-75329 A JP 2020-101659 A

The present invention has been made based on the above circumstances, and its object is to provide a positive-type photosensitive resin composition that enables positive patterning without residue, can form microlenses having a desired spherical or hemispherical shape even in a low-temperature process of 130°C or less, and provides microlenses formed with excellent transparency, chemical resistance, and long-term reliability.

（式中、Ｒ^０は水素原子又はメチル基を表し、Ｒ^１は単結合又は炭素原子数１又は２のアルキレン基を表し、Ｒ^２はメチル基を表し、ａは１又は２を表し、ｂは０乃至２の整数を表す。） The present inventors have conducted intensive research to solve the above problems, and as a result have completed the present invention. A first aspect of the present invention is a positive-type photosensitive resin composition comprising the following component (A), the following component (B), the following component (C), and a solvent:
Component (A): (a1) a monomer represented by the following formula (1), (a2) a monomer containing an epoxy ring, and (a3) a copolymer of a monomer containing a hydroxyl group having an acid dissociation constant pKa of 14 or more, the copolymer not containing a carboxyl group or a carboxylic anhydride group. Component (B): a quinone diazide compound. Component (C): a photoacid generator.

(In the formula, ^R0 represents a hydrogen atom or a methyl group, ^R1 represents a single bond or an alkylene group having 1 or 2 carbon atoms, ^R2 represents a methyl group, a represents 1 or 2, and b represents an integer of 0 to 2.)

（式中、Ｒ^０は水素原子又はメチル基を表し、Ｒ^３は下記式（Ｉ）で表される２価の有機基を表し、Ｒ^４は下記式（４）又は下記式（５）で表される１価の有機基を表し、Ｒ^５は下記式（Ｉ´）で表される１価の有機基を表す。）

（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の整数を表し、＊は前記式（２）又は前記式（３）で表されるモノマーのアルケニル基との結合手を表し、・は前記式（４）又は前記式（５）で表される１価の有機基との結合手を表す。） The (a2) monomer containing an epoxy ring is, for example, a monomer represented by the following formula (2), and the (a3) monomer containing a hydroxy group having an acid dissociation constant pKa of 14 or more is, for example, a monomer represented by the following formula (3).

(In the formula, ^R0 represents a hydrogen atom or a methyl group, ^R3 represents a divalent organic group represented by the following formula (I), ^R4 represents a monovalent organic group represented by the following formula (4) or (5), and ^R5 represents a monovalent organic group represented by the following formula (I').

(In the formula, c represents an integer of 0 to 3, d represents an integer of 1 to 3, e each independently represents an integer of 2 to 6, * represents a bond to the alkenyl group of the monomer represented by formula (2) or formula (3), and · represents a bond to the monovalent organic group represented by formula (4) or formula (5).)

（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は単結合又は炭素原子数１又は２のアルキレン基を表し、Ｒ^２はメチル基を表し、ｂは０乃至２の整数を表し、Ｒ^４は下記式（４）又は下記式（５）で表される１価の有機基を表し、ｅは２乃至６の整数を表す。）

The component (A) is, for example, a copolymer having a structural unit represented by the following formula (1a), a structural unit represented by the following formula (2a), and a structural unit represented by the following formula (3a).

(In the formula, ^R0 each independently represents a hydrogen atom or a methyl group, ^R1 represents a single bond or an alkylene group having 1 or 2 carbon atoms, ^R2 represents a methyl group, b represents an integer of 0 to 2, ^R4 represents a monovalent organic group represented by the following formula (4) or the following formula (5), and e represents an integer of 2 to 6.)

The polystyrene-equivalent weight average molecular weight of component (A) is, for example, 5,000 to 30,000.

（式中、Ｒ^６は炭素原子数１乃至１０の炭化水素基又はパーフルオロアルキル基を表し、Ｒ^７は炭素原子数１乃至８の直鎖状のアルキル基もしくはアルコキシ基、又は炭素原子数３乃至８の分岐鎖状のアルキル基もしくはアルコキシ基を表す。） The component (C) is, for example, a nonionic photoacid generator. The nonionic photoacid generator is, for example, a photoacid generator represented by the following formula (6).

(In the formula, ^R6 represents a hydrocarbon group or a perfluoroalkyl group having 1 to 10 carbon atoms, and ^R7 represents a linear alkyl group or an alkoxy group having 1 to 8 carbon atoms, or a branched alkyl group or an alkoxy group having 3 to 8 carbon atoms.)

The positive photosensitive resin composition of the present invention may further contain the following component (D).
Component (D): Multifunctional epoxy compound

The positive photosensitive resin composition of the present invention may further contain the following component (E).
Component (E): Sensitizer

The positive photosensitive resin composition of the present invention is used, for example, for producing microlenses.

A second aspect of the present invention is a cured film obtained from the positive photosensitive resin composition.

A third aspect of the present invention is a microlens made from the positive photosensitive resin composition.

A fourth aspect of the present invention is a method for producing a microlens, comprising: a coating step of coating the positive photosensitive resin composition on a substrate to form a resin film; a first exposure step of exposing at least a portion of the resin film to light after the coating step; a development step of removing the exposed portions of the resin film with a developer after the first exposure step to form a pattern of the unexposed portions of the resin film; a second exposure step of further exposing the pattern after the development step; and a post-bake step of heating the pattern at a temperature of 130°C or less after the second exposure step.

After the development step and before the second exposure step, a reflow step may be included in which the pattern is heated at a temperature of 130°C or less.

The substrate is, for example, a substrate on which a color filter is formed.

According to the present invention, a positive-type photosensitive resin composition can be provided which simultaneously contains component (A), which is a specific copolymer, component (B), which is a quinone diazide compound, and component (C), which is a photoacid generator, thereby enabling positive patterning without residue, and capable of forming microlenses having the desired spherical or hemispherical shape even in a low-temperature process of 130°C or less, and in which the formed microlenses have excellent transparency, chemical resistance, and long-term reliability.

（式中、Ｒ^０は水素原子又はメチル基を表し、Ｒ^１は単結合又は炭素原子数１又は２のアルキレン基を表し、Ｒ^２はメチル基を表し、ａは１又は２を表し、ｂは０乃至２の整数を表す。） The positive photosensitive resin composition of the present invention will now be described in more detail.
[Component (A)]
The component (A) contained in the positive photosensitive resin composition of the present invention is a copolymer of (a1) a monomer represented by the following formula (1), (a2) a monomer containing an epoxy ring, and (a3) a monomer containing a hydroxy group having an acid dissociation constant pKa of 14 or more, and is a copolymer containing no carboxy groups or carboxylic anhydride groups. Here, the carboxylic anhydride group is a divalent group represented by -CO-O-CO-:

(In the formula, ^R0 represents a hydrogen atom or a methyl group, ^R1 represents a single bond or an alkylene group having 1 or 2 carbon atoms, ^R2 represents a methyl group, a represents 1 or 2, and b represents an integer of 0 to 2.)

(a1) Examples of monomers represented by formula (1) include N-(2-hydroxyphenyl)(meth)acrylamide, N-(3-hydroxyphenyl)(meth)acrylamide, N-(4-hydroxyphenyl)(meth)acrylamide, N-(4-hydroxybenzyl)(meth)acrylamide, N-(4-hydroxyphenethyl)(meth)acrylamide, N-(3,5-dimethyl-4-hydroxyphenyl)(meth)acrylamide, N-(3,5-dimethyl-4-hydroxybenzyl)(meth)acrylamide, and N-(3,5-dimethyl-4-hydroxyphenethyl)(meth)acrylamide. These monomers may be used alone or in combination of two or more.

(a1) The ratio of the monomer represented by formula (1) is 5 parts by mass to 60 parts by mass, preferably 8 parts by mass to 50 parts by mass, and more preferably 10 parts by mass to 40 parts by mass, per 100 parts by mass of the monomers (a1), (a2) and (a3).

これらのモノマーは１種単独で使用しても、２種以上を組み合わせて使用してもよい。 The epoxy ring-containing monomer (a2) is a monomer having at least one epoxy ring in the molecule, and specific examples thereof include monomers represented by the following formulas (2-1) to (2-16).

These monomers may be used alone or in combination of two or more.

The ratio of the monomer containing an epoxy ring (a2) is 20 parts by mass to 80 parts by mass, preferably 30 parts by mass to 70 parts by mass, and more preferably 40 parts by mass to 60 parts by mass per 100 parts by mass of the monomers (a1), (a2) and (a3).

これらのモノマーは１種単独で使用しても、２種以上を組み合わせて使用してもよい。 (a3) The monomer containing a hydroxy group having an acid dissociation constant pKa of 14 or more is a monomer having at least one hydroxy group having an acid dissociation constant pKa (the lowest value in the case of a polyvalent acid) of 14 or more, and specific examples thereof include monomers represented by the following formulas (3-1) to (3-25). The monomer does not contain a functional group having an acid dissociation constant pKa of 13 or less, such as a silanol group, a fluoroalcohol group, a maleimide group, a carboxy group, or a phenolic hydroxy group.

These monomers may be used alone or in combination of two or more.

(a3) The proportion of monomers containing a hydroxy group having an acid dissociation constant pKa of 14 or more is 5 parts by mass to 60 parts by mass, preferably 8 parts by mass to 50 parts by mass, and more preferably 10 parts by mass to 40 parts by mass per 100 parts by mass of the monomers (a1), (a2) and (a3).

The weight average molecular weight of component (A), calculated as the polystyrene equivalent weight average molecular weight _Mw by gel permeation chromatography (GPC), is 5,000 to 30,000, preferably 5,000 to 20,000, and more preferably 5,000 to 15,000. By keeping the weight average molecular weight of component (A) within the above range, a good pattern can be formed after development without impairing chemical resistance.

The glass transition temperature of component (A) is 70°C to 130°C. By keeping the glass transition temperature of component (A) within this range, it has good reflow properties even in low-temperature processes at 130°C or less, and microlenses of the desired truncated or hemispherical shape can be produced.

[(B) Component]
The component (B) contained in the positive photosensitive resin composition of the present invention is not particularly limited as long as it is a compound having a 1,2-quinonediazide group, and for example, a condensate of a hydroxy group-containing compound and a 1,2-naphthoquinonediazide sulfonic acid halide can be used. Specifically, a compound in which 10 mol % to 100 mol %, preferably 20 mol % to 95 mol %, of the hydroxy groups of the hydroxy group-containing compound are esterified with the 1,2-naphthoquinonediazide sulfonic acid halide can be used. For the condensation reaction, various known methods can be adopted.

Examples of the hydroxy group-containing compound include the compounds shown below.
Dihydroxybenzophenones such as 2,4-dihydroxybenzophenone;
Trihydroxybenzophenones such as 2,3,4-trihydroxybenzophenone and 2,4,6-trihydroxybenzophenone;
tetrahydroxybenzophenones such as 2,4,2',4'-tetrahydroxybenzophenone, 2,3,4,3'-tetrahydroxybenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, 2,3,4,2'-tetrahydroxy-4'-methylbenzophenone, and 2,3,4,4'-tetrahydroxy-3'-methoxybenzophenone;
Pentahydroxybenzophenones such as 2,3,4,2',4'-pentahydroxybenzophenone and 2,3,4,2',6'-pentahydroxybenzophenone;
hexahydroxybenzophenones such as 2,4,6,3',4',5'-hexahydroxybenzophenone and 3,4,5,3',4',5'-hexahydroxybenzophenone;
2,2-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,3,3-tris(4-hydroxyphenyl)butane, bis(2,4-dihydroxyphenyl)methane, bis(p-hydroxyphenyl)methane, tris(p-hydroxyphenyl)methane, 1,1,1-tris(p-hydroxyphenyl)ethane, bis(2,3,4-trihydroxyphenyl)methane, 2,2-bis(2,3,4-trihydroxyphenyl)propane, 1,1,3-tris(2,5 (polyhydroxyphenyl)alkanes such as 4,4'-[1-[4-[1-[4-hydroxyphenyl]-1-methylethyl]phenyl]ethylidene]bisphenol, bis(2,5-dimethyl-4-hydroxyphenyl)-2-hydroxyphenylmethane, 3,3,3',3'-tetramethyl-1,1'-spirobiindene-5,6,7,5',6',7'-hexanol, and 2,2,4-trimethyl-7,2',4'-trihydroxyflavan;
Other compounds such as phenol, o-cresol, m-cresol, p-cresol, hydroquinone, resorcinol, catechol, methyl gallate, ethyl gallate, 2-methyl-2-(2,4-dihydroxyphenyl)-4-(4-hydroxyphenyl)-7-hydroxychroman, 1-[1-(3-{1-(4-hydroxyphenyl)-1-methylethyl}-4,6-dihydroxyphenyl)-1-methylethyl]-3-(1-(3-{1-(4-hydroxyphenyl)-1-methylethyl}-4,6-dihydroxyphenyl)-1-methylethyl)benzene, and 4,6-bis{1-(4-hydroxyphenyl)-1-methylethyl}-1,3-dihydroxybenzene.
Among these compounds, 2,3,4,4'-tetrahydroxybenzophenone, 1,1,1-tris(p-hydroxyphenyl)ethane, and 4,4'-[1-[4-[1-[4-hydroxyphenyl]-1-methylethyl]phenyl]ethylidene]bisphenol are preferred.

The 1,2-naphthoquinone diazide sulfonic acid halide is preferably 1,2-naphthoquinone diazide sulfonic acid chloride, more preferably 1,2-naphthoquinone-2-diazide-4-sulfonic acid chloride and 1,2-naphthoquinone-2-diazide-5-sulfonic acid chloride, and even more preferably 1,2-naphthoquinone-2-diazide-5-sulfonic acid chloride.

The compound of component (B) may be used alone or in combination of two or more types.

The content of component (B) in the positive photosensitive resin composition of the present invention is 5 to 100 parts by mass, preferably 10 to 60 parts by mass, and more preferably 15 to 40 parts by mass, relative to 100 parts by mass of component (A). By setting the content of component (B) within the above range, the difference in solubility in an alkaline developer between exposed and unexposed areas can be increased without significantly reducing sensitivity, making positive patterning possible with a relatively low exposure dose.

[(C) Component]
The component (C) contained in the positive photosensitive resin composition of the present invention is not particularly limited as long as it is a compound that can generate an acid having an acid dissociation constant pKa of 4 or less upon exposure to light, and examples of the component (C) include ionic photoacid generators and nonionic photoacid generators.

As the ionic photoacid generator, for example, the following products and compounds can be used.
ADEKA ARCLES (registered trademark) SP-056, SP-171 (all manufactured by ADEKA CORPORATION), CPI (registered trademark)-100B(40), CPI-100P, CPI-101A, CPI-110A, CPI-110B, CPI-110P, CPI-200K, CPI-210S, CPI-300, CPI-310B, CPI-310FG, CPI-400, CPI-410B, CPI-410S, VC-1FG, ES-1B (all manufactured by San-Apro Co., Ltd.), TPS-TF, TPS-CS, TPS-PFBS (all manufactured by Toyo Gosei Co., Ltd.), TPS arylsulfonium salts such as TPS-102, TPS-103, TPS-105, TPS-106, TPS-109, TPS-200, TPS-300, TPS-1000, HDS-109, MDS-103, MDS-105, MDS-109, MDS-205, MDS-209, BDS-109, MNPS-109, DTS-102, DTS-103, DTS-105, DTS-200, NDS-103, NDS-105, NDS-155, and NDS-165 (all manufactured by Midori Chemical Co., Ltd.);
Adeka Arcles (registered trademark) SP-140 (manufactured by ADEKA CORPORATION), IK-1, IK-1PC (80), IK-1FG (manufactured by San-Apro Co., Ltd.), DTBPI-PFBS (manufactured by Toyo Gosei Co., Ltd.), DPI-105, DPI-106, DPI-109, DPI-201, BI-105, MPI-105, MPI-106, MPI-109, BBI-102, BBI-103, BBI-105, BBI-106, BBI-109, BBI-110, BBI-200, BBI-201, BBI-300, and BBI-301 (manufactured by Midori Chemical Co., Ltd.) and other aryl iodonium salts.

As the nonionic photoacid generator, for example, the following products and compounds can be used.
N-sulfonyloxyimides such as ADEKA ARCLES (registered trademark) SP-082, SP-606 (manufactured by ADEKA Corporation), NA-CS1, NP-TM2, NP-SE10 (manufactured by San-Apro Co., Ltd.), SI-105, SI-106, PI-106, NDI-101, NDI-105, NDI-106, NDI-109, NDI-1001, NDI-1004, NAI-100, NAI-101, NAI-105, NAI-106, NAI-109, NAI-1002, NAI-1003, and NAI-1004 (manufactured by Midori Chemical Co., Ltd.);
Oxime sulfonates such as IRGACURE (registered trademark) PAG103, PAG121, and PAG203 (all manufactured by BASF Japan Ltd.), PAI-01, PAI-101, PAI-106, PAI-1001, PAI-1002, PAI-1003, and PAI-1004 (all manufactured by Midori Chemical Industry Co., Ltd.);
TAZ-100, TAZ-101, TAZ-102, TAZ-103, TAZ-104, TAZ-107, TAZ-108, TAZ-109, TAZ-110, TAZ- Triazines such as 113, TAZ-114, TAZ-118, TAZ-122, TAZ-123, TAZ-203, and TAZ-204 (all manufactured by Midori Kagaku Co., Ltd.).

Among these ionic photoacid generators and nonionic photoacid generators, from the viewpoint of storage stability and sensitivity, nonionic photoacid generators are preferred, N-sulfonyloxyimides are more preferred, and the compound represented by formula (6) is even more preferred. Specific examples of the compound represented by formula (6) include the compounds represented by the following formulas (6-1) to (6-28).

The compound of component (C) may be used alone or in combination of two or more types.

The content of component (C) in the positive photosensitive resin composition of the present invention is 0.1 to 10 parts by mass, preferably 0.5 to 5 parts by mass, per 100 parts by mass of component (A). By keeping the content of component (C) within the above range, it is possible to improve chemical resistance without impairing transparency.

[(D) Component]
The component (D) contained as an optional component in the positive photosensitive resin composition of the present invention is not particularly limited as long as it is a compound having at least two epoxy rings in the molecule, and for example, the following products and compounds can be used.
EPICLON (registered trademark) 830, 830-S, 835, 840, 840-S, 850, 850-S, 850-LC, and HP-820 (all manufactured by DIC Corporation), DENACOL (registered trademark) EX-201, EX-211, EX-212, EX-252, EX-810, EX-811, EX-821, and EX-8 30, EX-832, EX-841, EX-850, EX-851, EX-861, EX-920, EX-931, EX-991L, EX-313, EX-314, EX-321, EX-321L, EX-411, EX-421, EX-512, EX-521, EX-612, EX-614, and EX-61 4B, and EX-622 (all manufactured by Nagase ChemteX Corporation), jER (registered trademark) 152, jER 630, jER 825, jER 827, jER 828, jER 828EL, jER 828US, and jER 828XA (all manufactured by Mitsubishi Chemical Corporation), TETRAD (registered trademark)-C and TETRAD-X (all manufactured by Mitsubishi Gas Chemical Company, Inc.), Celloxide (registered trademark) 2021P, and 2081 , Epolead (registered trademark) GT401 (all manufactured by Daicel Corporation), Epotohto (registered trademark) YD-115, YD-115CA, YD-127, YD-128, YD-128G, YD-128S, YD-128CA, YD-8125, YD-825GS, YDF-170, YDF-170N, YDF-8170C, YD F-870GS, ZX-1059, YH-404, YH-434, YH-434L, YH-513, YH-523, ST-3000 (all manufactured by Nippon Steel Chemical & Material Co., Ltd.), ADEKA RESIN (registered trademark) EP-4100, EP-4100G, EP-4100E, EP-4100TX, EP-4300E, EP-4 100, EP-4400, EP-4520S, EP-4530, EP-4901, EP-4901E, EP-4000, EP-4005, EP-7001 , EP-4080E, EPU-6, EPU-7N, EPU-11F, EPU-15F, EPU-1395, EPU-73B, EPU-17, EPU-17 T-6, EPR-1415-1, EPR-2000, EPR-2007, ED-503, ED-503G, ED-506, E D-523T, ED-505 (manufactured by ADEKA Co., Ltd.), Sumiepoxy (registered trademark) ELM-434, ELM-434L, ELM-434VL, ELM-100 , ELM-100H (all manufactured by Sumitomo Chemical Co., Ltd.), Epolite M-1230, Epolite 40E, Epolite 100E, Epolite 200E, Epolite 400E, Epolite 70P, Epolite 200P, Epolite 400P, Epolite 1500NP, Epolite 1600, Epolite 80MF, Epolite 4000, Epolite 3002(N) (all manufactured by Kyoeisha Chemical Co., Ltd.), and multifunctional epoxy resins such as THI-DE (manufactured by ENEOS Corporation).

The compound (D) may be used alone or in combination of two or more.

When the positive photosensitive resin composition of the present invention contains component (D), the content of component (D) is 5 parts by mass to 100 parts by mass, preferably 10 parts by mass to 50 parts by mass, per 100 parts by mass of component (A). By keeping the content of component (D) within the above range, chemical resistance can be improved.

[(E) component]
The component (E) contained as an optional component in the positive photosensitive resin composition of the present invention is not particularly limited as long as it is a substance that can transfer the energy of irradiated light to another substance, and examples thereof include p-toluquinone, 1-phenyl-1,2-propanedione, phenanthrene, anthracene, 9,10-diethoxyanthracene, 9,10-dipropyloxyanthracene, 9,10-dibutoxyanthracene, 9,10-dioctanoyloxyanthracene, 3,7-dimethoxyanthracene, pyrene, perylene, xanthone, thioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, and 2-isopropylthioxanthone.

The compound of component (E) may be used alone or in combination of two or more types.

When the positive photosensitive resin composition of the present invention contains component (E), the content of component (E) is 0.01 to 5 parts by mass, preferably 0.05 to 3 parts by mass, and more preferably 0.1 to 1 part by mass, relative to 100 parts by mass of component (A). By keeping the content of component (E) within the above range, it is possible to effectively exert a sensitizing effect on the photoacid generator of component (C) without impairing transparency, and to improve chemical resistance.

[solvent]
The solvent contained in the positive photosensitive resin composition of the present invention is not particularly limited as long as it dissolves the components (A) to (C) and any optional components added as necessary. For example, all organic solvents such as hydrocarbons, halogenated hydrocarbons, ethers, alcohols, aldehydes, ketones, esters, amides, and nitriles can be used.

Examples of the hydrocarbons include n-pentane, cyclopentane, methylcyclopentane, n-hexane, isohexane, cyclohexane, methylcyclohexane, ethylcyclohexane, n-heptane, benzene, toluene, o-xylene, m-xylene, p-xylene, and mesitylene.

Examples of the halogenated hydrocarbons include dichloromethane, chloroform, carbon tetrachloride, chloroethane, dichloroethane, trichloroethane, tetrachloroethane, hexachloroethane, dichloroethylene, trichloroethylene, tetrachloroethylene, chlorobenzene, hydrofluorocarbons and perfluorocarbons.

Examples of the ethers include diethyl ether, di-n-propyl ether, diisopropyl ether, di-n-butyl ether, diisobutyl ether, di-tert-butyl ether, di-n-pentyl ether, diisopentyl ether, di-n-hexyl ether, methyl-n-propyl ether, methyl isopropyl ether, ethyl-n-propyl ether, ethyl isopropyl ether, n-butyl methyl ether, isobutyl methyl ether, tert-butyl methyl ether, n-butyl ethyl ether, isobutyl ethyl ether, tert-butyl ethyl ether, methyl-n-pentyl ether, cyclopentyl methyl ether, n-hexyl methyl ether, cyclohexyl methyl ether, tetrahydrofuran, tetrahydropyran, 1,3-dioxane, 1,4-dioxane, Examples of the dimethyl ether include xanthane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dibutyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene glycol dibutyl ether, tripropylene glycol dimethyl ether, tripropylene glycol diethyl ether, and tripropylene glycol dibutyl ether.

The alcohols include, for example, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-2-butanol, neopentyl alcohol, cyclopentanol, methylcyclopentanol, 1-hexanol, 2-hexanol, 3-hexanol, cyclohexanol, methylcyclohexanol, 1-heptanol, 2-heptanol, 3-heptanol, 4- Monohydric alcohols such as heptanol, 1-octanol, 2-octanol, 3-octanol, 4-octanol, 2-ethyl-1-hexanol, benzyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether and tripropylene glycol monobutyl ether; ethylene glycol, diethylene glycol Examples of the dihydric alcohol include ethylene glycol, triethylene glycol, tetraethylene glycol, 1,3-propanediol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 1,5-pentanediol, 1,4-pentanediol, 1,3-pentanediol, 1,2-pentanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, and 1,2-hexanediol, as well as trihydric alcohols such as glycerin.

Examples of the aldehydes include ethanal, propanal, 2-methyl-1-propanal, butanal, 3-methylbutanal, pentanal and benzaldehyde.

Examples of the ketones include acetone, 2-butanone, 2-pentanone, 3-pentanone, cyclopentanone, 2,4-pentanedione, 4-methyl-2-pentanone, 4-hydroxy-4-methyl-2-pentanone, cyclohexanone, and 2-heptanone.

Examples of the esters include methyl formate, ethyl formate, n-propyl formate, isopropyl formate, n-butyl formate, isobutyl formate, tert-butyl formate, n-pentyl formate, isopentyl formate, methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, tert-butyl acetate, n-pentyl acetate, isopentyl acetate, cyclopentyl acetate, n-hexyl acetate, isohexyl acetate, cyclohexyl acetate, n-heptyl acetate, isoheptyl acetate, n-octyl acetate, isooctyl acetate, benzyl acetate, and ethylene glycol monoacetate. monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol diacetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, triethylene glycol monomethyl ether acetate, triethylene glycol monoethyl ether acetate, triethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether acetate, propylene glycol diacetate, dipropylene glycol monomethyl Ether acetate, dipropylene glycol monoethyl ether acetate, dipropylene glycol monobutyl ether acetate, tripropylene glycol monomethyl ether acetate, tripropylene glycol monoethyl ether acetate, tripropylene glycol monobutyl ether acetate, methyl propionate, ethyl propionate, n-propyl propionate, isopropyl propionate, n-butyl propionate, isobutyl propionate, tert-butyl propionate, methyl butyrate, ethyl butyrate, n-propyl butyrate, isopropyl butyrate, n-butyl butyrate, isobutyl butyrate, tert-butyl butyrate, methyl isobutyrate, ethyl isobutyrate, n-propyl butyrate, propyl isobutyrate, isopropyl isobutyrate, n-butyl isobutyrate, isobutyl isobutyrate, tert-butyl isobutyrate, methyl lactate, ethyl lactate, n-propyl lactate, isopropyl lactate, n-butyl lactate, isobutyl lactate, tert-butyl lactate, methyl acetoacetate, ethyl acetoacetate, n-propyl acetoacetate, isopropyl acetoacetate, n-butyl acetoacetate, isobutyl acetoacetate, tert-butyl acetoacetate, dimethyl malonate, diethyl malonate, triacetin, γ-butyrolactone, γ-valerolactone, γ-caprolactone, δ-valerolactone, δ-caprolactone and ε-caprolactone.

Examples of the amides include N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylisobutyramide, N-methylpyrrolidone, and N-ethylpyrrolidone.

Examples of the nitriles include acetonitrile, propionitrile, and butyronitrile.

These solvents may be used alone or in combination of two or more.

Among these solvents, from the viewpoint of improving the leveling properties of the cured film formed by applying the positive photosensitive resin composition of the present invention to a substrate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether, propylene glycol monopropyl ether, 2-heptanone, ethyl lactate, n-butyl lactate, cyclopentanone and cyclohexanone are preferred.

[Surfactants and other additives]
The positive photosensitive resin composition of the present invention may optionally contain a surfactant for the purpose of improving the coating property. Examples of the surfactant include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, and polyoxyethylene oleyl ether, polyoxyethylene alkylaryl ethers such as polyoxyethylene octylphenyl ether and polyoxyethylene nonylphenyl ether, polyoxyethylene/polyoxypropylene block copolymers, sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, and sorbitan tristearate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, and polyoxyethylene sorbitan tristearate, and other polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, and polyoxyethylene sorbitan tristearate. Nonionic surfactants such as ethylene sorbitan fatty acid esters, EFTOP (registered trademark) EF301, EF303, EF352 (all manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.), Megafac (registered trademark) F-171, F-173, R-30, R-40, R-40-LM (all manufactured by DIC Corporation), Fluorad FC430, FC431 (all manufactured by Sumitomo 3M Limited), Asahiguard (registered trademark) AG710, Surflon (registered trademark) S-382, and Surflon SC1 Fluorine-based surfactants such as Ftergent series (manufactured by Neos Co., Ltd.), FTX-206D, FTX-212D, FTX-218, FTX-220D, FTX-230D, FTX-240D, FTX-212P, FTX-220P, FTX-228P, FTX-240G, etc., and organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.). These surfactants may be used alone or in combination of two or more.

When the positive-type photosensitive resin composition of the present invention contains a surfactant, the content of the surfactant is 0.001 parts by mass to 3 parts by mass, preferably 0.005 parts by mass to 1 part by mass, and more preferably 0.01 parts by mass to 0.5 parts by mass, per 100 parts by mass of the total solids content excluding the solvent in the positive-type photosensitive resin composition.

The positive photosensitive resin composition of the present invention may further contain additives such as curing aids, antioxidants, ultraviolet absorbers, plasticizers, adhesion aids, etc., as necessary, as long as the effects of the present invention are not impaired.

[Method for preparing positive-type photosensitive resin composition]
The method for preparing the positive photosensitive resin composition of the present invention is not particularly limited, but may be, for example, a method in which the components (A) to (C) and optionally other components are dissolved in a solvent to prepare a homogeneous solution. If necessary, the solution may be filtered using a filter having a pore size of 0.1 μm to 10 μm.

[Method of manufacturing microlenses]
An example of the production of a microlens using the positive photosensitive resin composition of the present invention will be described.
<Coating process>
The positive photosensitive resin composition of the present invention is applied onto a substrate (e.g., a semiconductor substrate, a glass substrate, a quartz substrate, a plastic substrate, a silicon wafer, and a substrate having various metal films or elements such as color filters formed on the surface thereof) by a suitable application method such as a spinner or coater, and then preferably prebaked using a heating means such as an oven or a hot plate to remove the solvent, thereby forming a resin film. The prebaking conditions are appropriately selected from the ranges of a bake temperature of 60° C. to 130° C. and a bake time of 20 seconds to 30 minutes. The thickness of the formed resin film is 0.1 μm to 10 μm, preferably 0.2 μm to 5 μm.

<First exposure process>
After the coating process, at least a part of the formed resin film is exposed through a predetermined mask. For example, g-line, i-line, KrF excimer laser, and ArF excimer laser can be used as the light beam for exposure. The exposure dose is appropriately selected from the range of 20 mJ/ ^cm2 to 2000 mJ/ ^cm2 .

<Developing process>
After the first exposure step, the exposed portion of the resin film is removed by a developer to form a pattern of the unexposed portion of the resin film. The development method is not particularly limited, but examples thereof include a dip method, a paddle method, and a spray method. The development conditions are appropriately selected from the range of a development temperature of 5° C. to 50° C. and a development time of 10 seconds to 300 seconds. The developer used is not particularly limited as long as it can remove the exposed portion, but examples thereof include an alkaline aqueous solution such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, sodium phosphate, potassium phosphate, ammonia, tetramethylammonium hydroxide (TMAH), and tetraethylammonium hydroxide (TEAH). In addition, an alkaline aqueous solution to which a surfactant or an organic solvent has been added in an appropriate amount may be used as the developer. These developers may be used alone or in combination of two or more.

After development, the film may be rinsed with a rinse solution to wash away the developer. After development or rinsing, the film may be dried by spinning in a spinning device such as a spinner or coater, or by blowing compressed air or compressed nitrogen onto the film to remove any remaining developer or rinse solution.

<Reflow process>
The method may include a reflow step of heating the pattern formed after the development step using a heating means such as an oven or a hot plate before the second exposure step described later. The reflow conditions are appropriately selected from the ranges of a bake temperature of 80° C. to 130° C. and a bake time of 1 minute to 90 minutes. Although it is possible to prepare a microlens having a sagittal or hemispherical shape even if the reflow step is omitted, it is possible to prepare a microlens having a sagittal or hemispherical shape at a lower temperature by including the reflow step.

<Second exposure process>
After the developing step or the reflow step, the pattern is further exposed to light. For example, g-line, i-line, KrF excimer laser, and ArF excimer laser can be used as the light beam for exposure. The exposure dose is appropriately selected from the range of 100 mJ/ ^cm2 to 5000 mJ/ ^cm2 .

<Post-bake process>
After the second exposure step, the pattern is heated using a heating means such as an oven or a hot plate, etc. The post-baking conditions are appropriately selected from the ranges of a baking temperature of 80° C. to 130° C. and a baking time of 1 minute to 90 minutes.

The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to the examples below.

The apparatus and conditions used for measuring the weight average molecular weight _Mw of the copolymer in terms of polystyrene are as follows:
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 Sample concentration: 10 mg/mL
Sample injection volume: 20 μL
Standard material: Monodisperse polystyrene Detector: Differential refractometer

The compounds used in the examples and comparative examples are as follows.
<(B) component>
B-1: Condensate of 1 mol of 4,4'-[1-[4-[1-[4-hydroxyphenyl]-1-methylethyl]phenyl]ethylidene]bisphenol and 1.5 mol of 1,2-naphthoquinone-2-diazide-5-sulfonic acid chloride (component (C))
C-1: ADEKA ARCLES (registered trademark) SP-606 (manufactured by ADEKA Corporation)
C-2: CPI-110P (manufactured by San-Apro Co., Ltd.)
<(D) component>
D-1: Epolead (registered trademark) GT401 (manufactured by Daicel Corporation)
<(E) component>
E-1: 2-isopropylthioxanthone (Tokyo Chemical Industry Co., Ltd.)
<Surfactant>
R-40: Megafac (registered trademark) R-40 (manufactured by DIC Corporation)

[Synthesis of component (A)]
<Synthesis Example 1>
A stirrer and 50 g of propylene glycol monomethyl ether as a solvent were placed in the flask, and the flask was immersed in a heated oil bath and maintained at 87°C. Next, a solution containing 30 g of N-(4-hydroxyphenyl)methacrylamide as a monomer represented by (a1) above, 60 g of 3,4-epoxycyclohexylmethyl methacrylate (the above formula (2-6)) as a monomer containing an epoxy ring (a2), 10 g of 2-hydroxyethyl methacrylate (the above formula (3-5)) as a monomer containing a hydroxy group having an acid dissociation constant pKa of 14 or more (a3), 4.5 g of 2,2'-azobisisobutyronitrile as a thermal radical generator, and 194 g of propylene glycol monomethyl ether as a solvent was placed in a dropping funnel and connected to the flask, and after nitrogen replacement, the mixture was dropped over 3 hours while stirring. After the dropping was completed, the mixture was allowed to react for another 15 hours to obtain a copolymer solution (solid content concentration 30% by mass). The resulting copolymer had a polystyrene-equivalent weight average molecular weight _Mw of 8000. Hereinafter, in this specification, the copolymer obtained in Synthesis Example 1 will be referred to as A-1.

<Synthesis Example 2>
A copolymer solution (solid content concentration 30 mass%) was obtained in the same manner as in Synthesis Example 1, except that 25 g of N-(4-hydroxyphenyl)methacrylamide, 15 g of 2-hydroxyethyl methacrylate, and 4.6 g of 2,2'-azobisisobutyronitrile were used. The polystyrene-equivalent weight average molecular weight M _W of the obtained copolymer was 8,000. Hereinafter, in this specification, the copolymer obtained in Synthesis Example 2 will be referred to as A-2.

<Synthesis Example 3>
A copolymer solution (solid content concentration 30 mass%) was obtained in the same manner as in Synthesis Example 1, except that 20 g of N-(4-hydroxyphenyl)methacrylamide, 20 g of 2-hydroxyethyl methacrylate, and 4.7 g of 2,2'-azobisisobutyronitrile were used. The polystyrene-equivalent weight average molecular weight M _W of the obtained copolymer was 8,000. Hereinafter, in this specification, the copolymer obtained in Synthesis Example 3 will be referred to as A-3.

<Synthesis Example 4>
A stirrer and 50 g of propylene glycol monomethyl ether as a solvent were placed in the flask, and the flask was immersed in a heated oil bath and maintained at 80°C. Next, a solution containing 40 g of N-(4-hydroxyphenyl)methacrylamide and 60 g of 3,4-epoxycyclohexylmethyl methacrylate as monomers, 4.4 g of 2,2'-azobisisobutyronitrile as a thermal radical generator, and 194 g of propylene glycol monomethyl ether as a solvent was placed in a dropping funnel and connected to the flask, and after nitrogen replacement, the mixture was dropped over 3 hours while stirring. After the dropwise addition was completed, the mixture was allowed to react for another 15 hours to obtain a copolymer solution (solid concentration 30% by mass). The polystyrene-equivalent weight average molecular weight M _W of the obtained copolymer was 11,000. Hereinafter, in this specification, the copolymer obtained in Synthesis Example 4 is referred to as A-4.

<Synthesis Example 5>
A stirrer and 90 g of propylene glycol monomethyl ether as a solvent were placed in the flask, and the flask was immersed in a heated oil bath and maintained at 70°C. Next, a solution containing 10 g of acrylic acid, 30 g of 4-hydroxybutyl acrylate, and 60 g of styrene as monomers, 4.5 g of 2,2'-azobisisobutyronitrile as a thermal radical generator, and 105 g of propylene glycol monomethyl ether as a solvent was placed in a dropping funnel and connected to the flask, and after nitrogen replacement, the mixture was dropped over 3 hours while stirring. After the dropwise addition was completed, the reaction was continued for another 15 hours to obtain a copolymer solution (solid concentration 35% by mass). The polystyrene-equivalent weight average molecular weight M _W of the obtained copolymer was 18,000. Hereinafter, in this specification, the copolymer obtained in Synthesis Example 5 is referred to as A-5.

[Preparation of positive-type photosensitive resin composition]
Example 1
70.0 g of copolymer A-1 obtained in Synthesis Example 1 as component (A) (21.0 g as solid content), 4.8 g of B-1 as component (B), 0.2 g of C-1 as component (C), 6.3 g of D-1 as component (D), 0.01 g of R-40 as surfactant, 6.6 g of propylene glycol monomethyl ether and 23.8 g of propylene glycol monomethyl ether acetate as solvents were mixed to obtain a uniform solution. Thereafter, the mixture was filtered using a polyethylene microfilter having a pore size of 0.10 μm to obtain a positive photosensitive resin composition (solid content concentration 29% by mass).

Example 2
70.0 g of copolymer A-1 obtained in Synthesis Example 1 as component (A) (21.0 g as solid content), 4.8 g of B-1 as component (B), 0.3 g of C-2 as component (C), 6.3 g of D-1 as component (D), 0.01 g of R-40 as surfactant, 6.8 g of propylene glycol monomethyl ether and 23.9 g of propylene glycol monomethyl ether acetate as solvents were mixed to obtain a uniform solution. Then, the mixture was filtered using a polyethylene microfilter having a pore size of 0.10 μm to obtain a positive photosensitive resin composition (solid content concentration 29% by mass).

Example 3
70.0 g of copolymer A-2 obtained in Synthesis Example 2 as component (A) (21.0 g as solid content), 4.8 g of B-1 as component (B), 0.2 g of C-1 as component (C), 6.3 g of D-1 as component (D), 0.01 g of R-40 as surfactant, 6.6 g of propylene glycol monomethyl ether and 23.8 g of propylene glycol monomethyl ether acetate as solvent were mixed to obtain a uniform solution. Then, the mixture was filtered using a polyethylene microfilter having a pore size of 0.10 μm to obtain a positive photosensitive resin composition (solid content concentration 29% by mass).

Example 4
70.0 g of copolymer A-3 obtained in Synthesis Example 3 as component (A) (21.0 g as solid content), 4.8 g of B-1 as component (B), 0.2 g of C-1 as component (C), 6.3 g of D-1 as component (D), 0.01 g of R-40 as surfactant, 30.2 g of propylene glycol monomethyl ether and 79.2 g of propylene glycol monomethyl ether acetate as solvents were mixed to obtain a uniform solution. Thereafter, the mixture was filtered using a polyethylene microfilter having a pore size of 0.10 μm to obtain a positive photosensitive resin composition (solid content concentration 17% by mass).

Example 5
70.0 g (21.0 g as solid content) of copolymer A-3 obtained in Synthesis Example 3 as component (A), 4.8 g of B-1 as component (B), 0.2 g of C-1 as component (C), 0.01 g of R-40 as surfactant, 25.1 g of propylene glycol monomethyl ether and 74.1 g of propylene glycol monomethyl ether acetate as solvents were mixed to obtain a homogeneous solution. The mixture was then filtered using a polyethylene microfilter having a pore size of 0.10 μm to obtain a positive photosensitive resin composition (solid content concentration 15% by mass).

Example 6
84.0 g of copolymer A-3 obtained in Synthesis Example 3 as component (A) (25.2 g as solid content), 5.8 g of B-1 as component (B), 0.2 g of C-1 as component (C), 7.6 g of D-1 as component (D), 0.05 g of E-1 as component (E), 0.01 g of R-40 as surfactant, 36.2 g of propylene glycol monomethyl ether and 95.0 g of propylene glycol monomethyl ether acetate as solvent were mixed to obtain a uniform solution. Then, the mixture was filtered using a polyethylene microfilter having a pore size of 0.10 μm to obtain a positive photosensitive resin composition (solid content concentration 17% by mass).

<Comparative Example 1>
70.0 g of copolymer A-4 obtained in Synthesis Example 4 not corresponding to component (A) (21.0 g as solid content), 4.8 g of B-1 as component (B), 0.2 g of C-1 as component (C), 6.3 g of D-1 as component (D), 0.01 g of R-40 as surfactant, 9.4 g of propylene glycol monomethyl ether as solvent, and 25.0 g of propylene glycol monomethyl ether acetate were mixed to obtain a uniform solution. Then, the mixture was filtered using a polyethylene microfilter having a pore size of 0.10 μm to obtain a positive photosensitive resin composition (solid content concentration 28% by mass).

<Comparative Example 2>
60.0 g of copolymer A-5 obtained in Synthesis Example 5 not corresponding to component (A) (21.0 g as solid content), 4.8 g of B-1 as component (B), 0.2 g of C-1 as component (C), 10.5 g of D-1 as component (D), 0.01 g of R-40 as surfactant, 3.8 g of propylene glycol monomethyl ether as solvent and 35.1 g of propylene glycol monomethyl ether acetate were mixed to obtain a uniform solution. Then, the mixture was filtered using a polyethylene microfilter having a pore size of 0.10 μm to obtain a positive photosensitive resin composition (solid content concentration 32% by mass).

Table 1 shows the components contained in the positive-type photosensitive resin compositions of Examples 1 to 6, and the contents of components (B) to (E) per 100 parts by mass of component (A).

[Patterning Evaluation]
The positive photosensitive resin compositions prepared in Examples 1 to 6 and Comparative Examples 1 and 2 were each applied onto a silicon wafer using a spin coater, and prebaked on a hot plate at 80° C. for 90 seconds to form a resin film having a thickness as shown in Table 2. Next, the resin film was subjected to a first exposure using an i-line stepper (NSR-2205i12D, NA=0.63, manufactured by Nikon Corporation) through a predetermined mask at an exposure dose as shown in Table 2. Here, as the mask, a mask forming a 4 μm×4 μm square dot pattern/4 μm space was used for the resin film having a thickness of 4 μm (Examples 1 to 3 and Comparative Examples 1 and 2), and a mask forming a 1 μm×1 μm square dot pattern/1 μm space was used for the resin film having a thickness of 1 μm (Examples 4 to 6). Thereafter, within 10 minutes from the first exposure, development was performed using a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution, and a 4 μm×4 μm square dot pattern was formed for the 4 μm thick resin film, and a 1 μm×1 μm square dot pattern was formed for the 1 μm thick resin film. The formed square dot pattern was observed at a magnification of 5000 times using a scanning electron microscope, and the patterning property was evaluated as “×” when the residue of the resin film was clearly visible in the space between adjacent square dot patterns, and as “○” when the residue of the resin film was not visible. The evaluation results are shown in Table 2.

[Lens shape evaluation]
Using the positive photosensitive resin compositions prepared in Examples 1 to 6 and Comparative Examples 1 and 2, a 4 μm×4 μm square dot pattern was formed on a silicon wafer for a 4 μm thick resin film, and a 1 μm×1 μm square dot pattern was formed for a 1 μm thick resin film on a silicon wafer according to the procedure described in [Patterning property evaluation]. The square dot pattern was then baked for 5 minutes on a hot plate at the reflow temperature described in Table 2. Furthermore, the i-line stepper was used to perform a second exposure on the entire surface of the square dot pattern at 500 mJ/cm ² , and then the square dot pattern was baked for 10 minutes on a hot plate at the post-bake temperature described in Table 2 to produce a microlens. Furthermore, the entire surface of a 1 μm x 1 μm square dot pattern formed using the positive photosensitive resin composition prepared in Example 4 was subjected to a second exposure at 500 mJ/ ^cm2 using the i-line stepper without baking at the reflow temperature (the reflow temperature is shown as "none" in Table 2), and then baked on a hot plate for 10 minutes at the post-bake temperature shown in Table 2 to produce microlenses. Microlenses that were shaped like a square prism or a truncated square pyramid were evaluated as "□", and those that were shaped like a spheroid or a hemisphere were evaluated as "◯". The evaluation results are shown in Table 2.

[Chemical resistance evaluation]
The positive photosensitive resin compositions prepared in Examples 1 to 6 and Comparative Examples 1 and 2 were each applied onto a silicon wafer using a spin coater, and prebaked on a hot plate at 80° C. for 90 seconds to form a resin film having a thickness as shown in Table 2. Next, the entire surface of the resin film was exposed to light at 500 mJ/cm ² using the i-line stepper, and then baked on a hot plate at the post-bake temperature as shown in Table 2 for 10 minutes to form a cured film. The silicon wafer on which the cured film was formed was immersed in propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, cyclohexanone, and an aqueous solution of tetramethylammonium hydroxide (TMAH) having a concentration of 2.38% by mass at 23° C. for 5 minutes. The thickness of the cured film before and after immersion was measured, and the change in thickness before and after immersion was calculated. When the film thickness of the film before immersion was increased or decreased by 10% or more for any of the solvents used for the immersion, the chemical resistance was evaluated as "x", and when the film thickness was increased or decreased by less than 10% for all of the solvents, the chemical resistance was evaluated as "○". The evaluation results are shown in Table 2.

[Transparency assessment]
The positive photosensitive resin compositions prepared in Examples 1 to 6 and Comparative Examples 1 and 2 were each applied onto a quartz substrate using a spin coater, and prebaked on a hot plate at 80° C. for 90 seconds to form a resin film having a thickness as shown in Table 2. Next, the entire surface of the resin film was exposed to light at 500 mJ/cm ² using the i-line stepper, and then baked on a hot plate at the post-bake temperature as shown in Table 2 for 10 minutes to form a cured film. The transmittance of the quartz substrate on which the cured film was formed was measured at a wavelength of 400 nm using a UV-2550 ultraviolet-visible spectrophotometer (manufactured by Shimadzu Corporation). When the transmittance at a wavelength of 400 nm was less than 90%, the transparency was evaluated as “x”, and when it was 90% or more, the transparency was evaluated as “○”. The evaluation results are shown in Table 2.

[Long-term reliability evaluation]
<HTS Testing>
Using the positive photosensitive resin compositions prepared in Examples 1 to 6, cured films were formed on quartz substrates according to the procedure described in the above [Transparency Evaluation]. The quartz substrates on which the cured films were formed were heated in an oven at 100° C. for 1,000 hours, and then the transmittance at a wavelength of 400 nm was measured using the above UV-Vis spectrophotometer. When the transmittance at a wavelength of 400 nm increased or decreased by 5% or more compared to the transmittance before heating for 1,000 hours, the result was evaluated as “x”, and when the transmittance increased or decreased by less than 5%, the result was evaluated as “○”. The evaluation results are shown in Table 2.

<THS Test>
Using the positive photosensitive resin compositions prepared in Examples 1 to 6, a cured film was formed on a quartz substrate according to the procedure described in the above [Transparency Evaluation]. The quartz substrate on which the cured film was formed was stored for 1,000 hours in a thermo-hygrostat chamber whose inside was kept at 85° C. and a relative humidity of 85%, and then the transmittance at a wavelength of 400 nm was measured using the above UV-visible spectrophotometer. When the transmittance at a wavelength of 400 nm increased or decreased by 5% or more compared to the transmittance before the 1,000-hour storage, it was evaluated as "x", and when the transmittance increased or decreased by less than 5%, it was evaluated as "○". The evaluation results are shown in Table 2.

<Xenon arc test>
Using the positive photosensitive resin compositions prepared in Examples 1 to 6, a cured film was formed on a quartz substrate according to the procedure described in the above [Transparency Evaluation]. A cut filter (L38, manufactured by Shibuya Optical Co., Ltd.) was attached to the quartz substrate on which the cured film was formed, and the substrate was exposed to 25 million [lx·h] in a xenon arc tester (Q-SUNXe-1, manufactured by Q-Lab Co., Ltd.), and the transmittance at a wavelength of 400 nm was measured using the ultraviolet-visible spectrophotometer. When the transmittance increased or decreased by 5% or more compared to the transmittance at a wavelength of 400 nm before exposure using the xenon arc tester, the transmittance was evaluated as "x", and when the transmittance increased or decreased by less than 5%, the transmittance was evaluated as "○".

The results in Table 2 show that by using the positive photosensitive resin composition of the present invention, positive patterning is possible without leaving any residue, and that microlenses having a truncated or hemispherical shape can be formed even in a low-temperature process at 130° C. or less, and that these microlenses have excellent transparency, chemical resistance, and long-term reliability.

Claims (14)

A positive photosensitive resin composition comprising the following component (A), component (B), component (C), and a solvent:
Component (A): (a1) a monomer represented by the following formula (1), (a2) a monomer containing an epoxy ring, and (a3) a copolymer of a monomer containing a hydroxyl group having an acid dissociation constant pKa of 14 or more, the copolymer not containing a carboxyl group or a carboxylic anhydride group. Component (B): a quinone diazide compound. Component (C): a photoacid generator.

(In the formula, ^R0 represents a hydrogen atom or a methyl group, ^R1 represents a single bond or an alkylene group having 1 or 2 carbon atoms, ^R2 represents a methyl group, a represents 1 or 2, and b represents an integer of 0 to 2.) 2. The positive photosensitive resin composition according to claim 1, wherein the (a2) monomer containing an epoxy ring is a monomer represented by the following formula (2), and the (a3) monomer containing a hydroxy group having an acid dissociation constant pKa of 14 or more is a monomer represented by the following formula (3):

(In the formula, each ^R0 independently represents a hydrogen atom or a methyl group, ^R3 represents a divalent organic group represented by the following formula (I), ^R4 represents a monovalent organic group represented by the following formula (4) or (5), and ^R5 represents a monovalent organic group represented by the following formula (I').

(In the formula, c represents an integer of 0 to 3, d represents an integer of 1 to 3, e each independently represents an integer of 2 to 6, * represents a bond to the alkenyl group of the monomer represented by formula (2) or formula (3), and · represents a bond to the monovalent organic group represented by formula (4) or formula (5).) 2. The positive photosensitive resin composition according to claim 1, wherein the component (A) is a copolymer having a structural unit represented by the following formula (1a), a structural unit represented by the following formula (2a), and a structural unit represented by the following formula (3a):

(In the formula, ^R0 each independently represents a hydrogen atom or a methyl group, ^R1 represents a single bond or an alkylene group having 1 or 2 carbon atoms, ^R2 represents a methyl group, b represents an integer of 0 to 2, ^R4 represents a monovalent organic group represented by the following formula (4) or the following formula (5), and e represents an integer of 2 to 6.)

The positive photosensitive resin composition according to claim 1, wherein the polystyrene-equivalent weight average molecular weight of component (A) is 5,000 to 30,000. The positive-type photosensitive resin composition according to claim 1, wherein the component (C) is a nonionic photoacid generator. The positive photosensitive resin composition according to claim 5 , wherein the nonionic photoacid generator is a photoacid generator represented by the following formula (6):

(In the formula, ^R6 represents a hydrocarbon group or a perfluoroalkyl group having 1 to 10 carbon atoms, and ^R7 represents a linear alkyl group or an alkoxy group having 1 to 8 carbon atoms, or a branched alkyl group or an alkoxy group having 3 to 8 carbon atoms.) The positive photosensitive resin composition according to claim 1 , further comprising the following component (D):
Component (D): Multifunctional epoxy compound The positive photosensitive resin composition according to claim 1 , further comprising the following component (E):
Component (E): Sensitizer The positive-type photosensitive resin composition according to claim 1, which is used for producing microlenses. A cured film obtained from the positive-type photosensitive resin composition according to any one of claims 1 to 9. A microlens made from the positive-type photosensitive resin composition according to any one of claims 1 to 9. A method for producing a microlens, comprising: a coating step of coating a substrate with the positive photosensitive resin composition according to any one of claims 1 to 9 to form a resin film; a first exposure step of exposing at least a part of the resin film to light after the coating step; a development step of removing the exposed parts of the resin film with a developer after the first exposure step to form a pattern of the unexposed parts of the resin film; a second exposure step of further exposing the pattern after the development step; and a post-bake step of heating the pattern at a temperature of 130°C or less after the second exposure step. The method for producing a microlens according to claim 12, further comprising a reflow step of heating the pattern at a temperature of 130°C or less after the developing step and before the second exposure step. The method for producing a microlens according to claim 12, wherein the base material is a substrate on which a color filter is formed.