JP2010054809A - Positive photosensitive resin composition for spacer formation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive photosensitive resin composition for spacer formation capable of easily forming highly flexible spacers of different heights simultaneously with bumps. <P>SOLUTION: A positive photosensitive resin composition with mass average molecular weight of 60,000 or more is used that contains an alkali soluble resin with mass average molecular weight of 60,000 or more containing a constitutional unit (a1) represented by the general formula (a-1) and a constitutional unit (a2) having a crosslinkable group, the proportion of the constitutional unit (a1) exceeding 40 mol%, and a quinone diazide group-containing compound. In the alkali soluble resin, the proportions of the constitutional unit (a1) and the constitutional unit (a2) are preferably 50-80 mol% and 20-50 mol% respectively. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a spacer-forming photosensitive resin composition for forming a spacer provided between two substrates of a liquid crystal panel.

  In a liquid crystal panel of a liquid crystal display device, since a liquid crystal material is sandwiched between two transparent substrates such as a glass substrate, a spacer may be formed between the two substrates so that the liquid crystal material can be filled. is necessary.

  Conventionally, in order to form a spacer, a method in which bead particles serving as a spacer are dispersed over the entire surface of the substrate has been adopted. However, the beads are also adhered to the pixel display portion, and the image contrast and display image quality are deteriorated. was there. Therefore, in recent years, various methods for forming the spacer with a photosensitive resin composition have been proposed (see Patent Documents 1 and 2). In this method, a photosensitive resin composition is applied onto a substrate, exposed through a predetermined mask, and then developed to form a dot-like spacer. A predetermined portion other than a pixel display portion Only the spacer can be formed.

  Also, a method of forming two types of spacers having different heights using a negative photosensitive resin composition has been proposed in order to cope with the problems of plastic deformation and destruction of the spacer due to excessive load on the liquid crystal panel. (See Patent Document 3). The spacer having a high height sets a gap between the substrates, deforms when a load is applied to the liquid crystal panel, and restores when the load is removed. On the other hand, the spacer having a low height disperses the load when an excessive load is applied to the liquid crystal panel, thereby preventing plastic deformation and destruction of the spacer having a high height.

Further, a method of forming a liquid crystal alignment control bump (hereinafter also referred to as “bump”) in an MVA (Multi-domain Vertically Aligned) liquid crystal display simultaneously with a spacer using a positive photosensitive resin composition is also proposed. (See Patent Document 4). Thus, the productivity of the liquid crystal display can be increased by forming the spacer and the bump at the same time.
JP 2006-184841 A JP 2006-308961 A JP 2008-15072 A JP 2004-333964 A

  By the way, if the spacer cannot be elastically deformed following the thermal expansion or contraction of the liquid crystal, vacuum bubbles (low temperature bubbles) may be generated in the liquid crystal panel. I must. In particular, when two types of spacers having different heights are formed, the spacers having a high height are required to have a high flexibility that easily deforms with respect to the load and restores when the load is removed. However, the conventional photosensitive resin compositions described in Patent Documents 1 to 4 cannot form a spacer having a high degree of flexibility required.

  In Patent Document 3, a negative photosensitive resin composition is used. However, since the exposed portion of the negative photosensitive resin composition is cured, spacers having different heights can be formed by one exposure. It was difficult. More specifically, when forming spacers having different heights, a further pattern is accumulated in a similar process on a pattern cured by a process including application, exposure, development, and washing of the photosensitive resin composition. There is a need. Therefore, in order to accurately form a pattern on the previously formed pattern, precise alignment of the mask at the time of exposure is required. Thus, in the case of using a negative photosensitive resin composition, not only the process becomes complicated, but also there is a problem of a decrease in yield due to mask displacement, so that spacers having different heights are formed. In addition to being able to form a flexible spacer, the photosensitive resin composition is also required to be positive.

  The present invention has been made in view of the problems as described above, and an object of the present invention is to form a highly flexible spacer and to easily form spacers having different heights by one exposure. In addition, another object of the present invention is to provide a positive photosensitive resin composition for forming a spacer capable of simultaneously forming bumps.

  The inventors of the present invention have made extensive studies to solve the above problems. As a result, it has been found that the above problems can be solved by using a positive photosensitive resin composition containing a specific alkali-soluble resin and a quinonediazide group-containing compound, and the present invention has been completed.

［上記一般式中、Ｒ^０は水素原子又はメチル基を表し、Ｒ^１は単結合又は炭素数１〜５のアルキレン基を表し、Ｒ^２は炭素数１〜５のアルキル基を表し、ａは１〜５の整数を表し、ｂは０〜４の整数を表し、ａ＋ｂは５以下である。なお、Ｒ^２が２以上存在する場合、これらのＲ^２は相互に異なっていてもよいし同じでもよい。］
More specifically, the present invention is a positive photosensitive resin composition for spacer formation containing an alkali-soluble resin and a quinonediazide group-containing compound, wherein the alkali-soluble resin is represented by the following general formula (a-1). The structural unit (a1) and the structural unit (a2) having a crosslinkable group, wherein the proportion of the structural unit (a1) is more than 40 mol% and 90 mol% or less, and the mass average molecular weight A positive photosensitive resin composition for forming a spacer, wherein the composition is 60000 to 160000.

[In the above general formula, R ⁰ represents a hydrogen atom or a methyl group, R ¹ represents a single bond or an alkylene group having 1 to 5 carbon atoms, R ² represents an alkyl group having 1 to 5 carbon atoms, and a represents Represents an integer of 1 to 5, b represents an integer of 0 to 4, and a + b is 5 or less. In the case where R ² is present 2 or more, these R ² may be the same or may be different from each other. ]

  If the positive photosensitive resin composition for spacer formation of the present invention (hereinafter referred to as “photosensitive resin composition”) is used, a highly flexible spacer can be formed. Accordingly, since it becomes easier to follow the contraction / expansion of the liquid crystal, even when the liquid crystal contracts / expands greatly, the generation of vacuum bubbles can be prevented and display defects such as color unevenness can be prevented.

  In addition, since the photosensitive resin composition of the present invention is a positive type, spacers having different heights can be formed simultaneously by half-tone exposure, and spacers and bumps can be formed simultaneously. As a result, the productivity of the liquid crystal display is improved.

  Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention. . In addition, although description may be abbreviate | omitted suitably about the location where description overlaps, the summary of invention is not limited.

  The photosensitive resin composition of the present invention contains an alkali-soluble resin and a quinonediazide group-containing compound.

［上記一般式中、Ｒ^０は水素原子又はメチル基を表し、Ｒ^１は単結合又は炭素数１〜５のアルキレン基を表し、Ｒ^２は炭素数１〜５のアルキル基を表し、ａは１〜５の整数を表し、ｂは０〜４の整数を表し、ａ＋ｂは５以下である。なお、Ｒ^２が２以上存在する場合、これらのＲ^２は相互に異なっていてもよいし同じでもよい。］ <Alkali-soluble resin>
The alkyl-soluble resin in the present invention includes a structural unit (a1) represented by the following general formula (a-1) and a structural unit (a2) having a crosslinkable group.

[In the above general formula, R ⁰ represents a hydrogen atom or a methyl group, R ¹ represents a single bond or an alkylene group having 1 to 5 carbon atoms, R ² represents an alkyl group having 1 to 5 carbon atoms, and a represents Represents an integer of 1 to 5, b represents an integer of 0 to 4, and a + b is 5 or less. In the case where R ² is present 2 or more, these R ² may be the same or may be different from each other. ]

In the general formula (a-1), R ⁰ is preferably a methyl group.

R ¹ is a single bond or a linear or branched alkylene group having 1 to 5 carbon atoms. Specific examples of R ¹ include a single bond, methylene group, ethylene group, propylene group, isopropylene group, n-butylene group, isobutylene group, tert-butylene group, pentylene group, isopentylene group, neopentylene group, and the like. It is done. Among these, a single bond, a methylene group, and an ethylene group are preferable. In particular, a single bond is preferable because alkali solubility can be improved.

  Further, a is preferably 1 from the viewpoint of the effects of the present invention and the ease of production.

Moreover, it is preferable that the hydroxyl group in the benzene ring is bonded to the 4-position when the carbon atom bonded to R ¹ is used as a reference (1-position).

R ² is a linear or branched alkyl group having 1 to 5 carbon atoms. Specific examples of R ² include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, isopentyl, neopentyl and the like. Among these, a methyl group or an ethyl group is preferable from the viewpoint of easy production.

Specific examples of the structural unit (a1) include those represented by the following structural formulas (a-1-1) to (a-1-3). In particular, a structural unit represented by the structural formula (a-1-2) is preferable.

［上記一般式中、Ｒ^０、Ｒ^１、Ｒ^２、ａ、ｂは上記と同様である。］ This structural unit (a1) is obtained by polymerizing polymerizable monomers represented by the following general formula (a-1) ′, or a polymerizable monomer represented by the following general formula (a-1) ′. The polymer can be introduced into an alkali-soluble resin by copolymerizing it with another polymerizable monomer.

[In the above general formula, R ⁰ , R ¹ , R ² , a and b are the same as above. ]

  The structural unit (a2) in the present invention is a structural unit having a crosslinkable group. This crosslinkable group is crosslinked by heat. By including the structural unit (a2), stability and durability as a permanent film (spacer, MVA bump, etc.) are improved. Examples of the crosslinkable group include an epoxy group and an oxetanyl group. Among these, it is preferable that this structural unit (a2) has an epoxy group from the ease of manufacture of a copolymer. And when structural unit (a2) has an epoxy group, there is a problem in storage stability as a composition, but storage stability is improved by using a copolymer in combination with structural unit (a1). Can be improved.

  The structural unit (a2) having an epoxy group as such a crosslinkable group includes, for example, glycidyl acrylate, glycidyl methacrylate, acrylate-β-methylglycidyl methacrylate, β-methylglycidyl methacrylate, glycidyl α-ethyl acrylate, α-n-propyl glycidyl acrylate, α-n-butyl glycidyl acrylate, acrylic acid-3,4-epoxybutyl, methacrylic acid-3,4-epoxybutyl, acrylic acid-6,7-epoxyheptyl, methacrylic acid -6,7-epoxyheptyl, α-ethylacrylic acid-6,7-epoxyheptyl, o-vinylbenzyl glycidyl ether, m-vinylbenzyl glycidyl ether, p-vinylbenzyl glycidyl ether, (3,4-epoxycyclohexyl) Polymerizable simple substance such as methyl methacrylate It can be induced by copolymerizing the body. These structural units (a2) may be used alone or in combination.

［上記一般式中、Ｒ^３は水素原子又はメチル基を表す。］ Particularly preferred structural units (a2) include structural units represented by general formula (a-2) ′ below. The structural unit (a2) ′ is preferably used from the viewpoints of ease of production, cost advantage, and solvent resistance of the resulting spacer.

[In the above general formula, R ³ represents a hydrogen atom or a methyl group. ]

  The alkali-soluble resin used in the present invention may contain a structural unit (a3) other than the structural units (a1) and (a2). This structural unit (a3) will not be specifically limited if it is a structural unit which does not have a carboxyl group. By not having a carboxyl group, developability and storage stability can be improved.

  In addition, the alkali-soluble resin used in the present invention includes a copolymer including the structural unit (a1) and the structural unit (a2) having an epoxy group as a crosslinkable group, and is derived from unsaturated carboxylic acids. Is not included, that is, it is particularly preferable not to include a structural unit having a carboxyl group. Thereby, chemical resistance and especially storage stability can be improved. The above configuration allows storage at room temperature.

  In the alkali-soluble resin, the content of the structural unit (a1) is more than 40 mol% and 90 mol% or less. It is preferable that it is 50 mol%-90 mol%, More preferably, it is 60 mol%-80 mol%. If content of a structural unit (a1) exists in the said range, sufficient alkali solubility can be provided with respect to the photosensitive resin composition of this invention.

  In the alkali-soluble resin, the content of the structural unit (a2) is preferably 10 mol% to 50 mol%, more preferably 20 mol% to 45 mol%. By making content of a structural unit (a2) into the said range, sufficient thermosetting can be provided to the photosensitive resin composition of this invention. By sandwiching the spacer between the substrates when the thermosetting is not progressing and then thermosetting, the adhesion between the spacer and the substrate is improved, which is particularly effective in preventing display unevenness due to a decrease in adhesion. Moreover, if content of a structural unit (a2) exists in the said range, the chemical resistance of the spacer formed will also increase.

  Furthermore, the structural unit (a3) in the alkali-soluble resin is preferably 0 mol% to 30 mol%, more preferably 0 mol% to 10 mol%, and most preferably not contained.

  In the present invention, an alkali-soluble resin composed of the structural unit (a1) and the structural unit (a2) is preferable. It is preferable that the alkali-soluble resin is composed of the above two components because the effect of improving the flexibility of the spacer is further enhanced.

  The mass average molecular weight of the alkali-soluble resin used in the present invention (Mw: measured value by gel permeation chromatography (GPC) in terms of polystyrene. The same applies in the present specification) is 60000 to 160000, and 70000 to 150,000. More preferably, it is more preferably 80000-150,000, and particularly preferably 85000-100,000. Since the alkali-soluble resin has a high mass average molecular weight as described above, a highly flexible spacer can be formed.

  The alkali-soluble resin can be produced by a known radical polymerization. That is, it can be produced by dissolving the polymerizable monomer for deriving the structural units (a1), (a2), and (a3), and a known radical polymerization initiator in a polymerization solvent, followed by heating and stirring. .

  Furthermore, the alkali-soluble resin may contain other polymers in addition to the copolymer. Other polymers include a polymer containing the structural unit (a3), a copolymer of the structural unit (a1) and the structural unit (a3), and a copolymer of the structural unit (a2) and the structural unit (a3). Etc. Other copolymers may be used alone or in combination of two or more. The other copolymer is preferably 0 part by mass to 50 parts by mass, and more preferably 0 part by mass to 30 parts by mass with respect to 100 parts by mass of the copolymer.

<Quinonediazide group-containing compound>
Specific examples of the quinonediazide group-containing compound include completely esterified products and partially esterified products of a phenol compound (also referred to as a phenolic hydroxyl group-containing compound) and a naphthoquinonediazide sulfonic acid compound.

Specific examples of the phenol compound include polyhydroxybenzophenones such as 2,3,4-trihydroxybenzophenone and 2,3,4,4′-tetrahydroxybenzophenone;
Tris (4-hydroxyphenyl) methane, bis (4-hydroxy-3-methylphenyl) -2-hydroxyphenylmethane, bis (4-hydroxy-2,3,5-trimethylphenyl) -2-hydroxyphenylmethane, Bis (4-hydroxy-3,5-dimethylphenyl) -4-hydroxyphenylmethane, bis (4-hydroxy-3,5-dimethylphenyl) -3-hydroxyphenylmethane, bis (4-hydroxy-3,5- Dimethylphenyl) -2-hydroxyphenylmethane, bis (4-hydroxy-2,5-dimethylphenyl) -4-hydroxyphenylmethane, bis (4-hydroxy-2,5-dimethylphenyl) -3-hydroxyphenylmethane, Bis (4-hydroxy-2,5-dimethylphenyl) -2-hydroxyl Nylmethane, bis (4-hydroxy-3,5-dimethylphenyl) -3,4-dihydroxyphenylmethane, bis (4-hydroxy-2,5-dimethylphenyl) -3,4-dihydroxyphenylmethane, bis (4- Hydroxy-2,5-dimethylphenyl) -2,4-dihydroxyphenylmethane, bis (4-hydroxyphenyl) -3-methoxy-4-hydroxyphenylmethane, bis (5-cyclohexyl-4-hydroxy-2-methylphenyl) ) -4-hydroxyphenylmethane, bis (5-cyclohexyl-4-hydroxy-2-methylphenyl) -3-hydroxyphenylmethane, bis (5-cyclohexyl-4-hydroxy-2-methylphenyl) -2-hydroxyphenyl Methane, bis (5-cyclohexyl-4-hydro Shi-2-methylphenyl) -3,4-trisphenol compounds such dihydroxyphenyl methane;
Linear type 3 such as 2,4-bis (3,5-dimethyl-4-hydroxybenzyl) -5-hydroxyphenol, 2,6-bis (2,5-dimethyl-4-hydroxybenzyl) -4-methylphenol Nuclear phenolic compounds;
1,1-bis [3- (2-hydroxy-5-methylbenzyl) -4-hydroxy-5-cyclohexylphenyl] isopropane, bis [2,5-dimethyl-3- (4-hydroxy-5-methylbenzyl) ) -4-hydroxyphenyl] methane, bis [2,5-dimethyl-3- (4-hydroxybenzyl) -4-hydroxyphenyl] methane, bis [3- (3,5-dimethyl-4-hydroxybenzyl)- 4-hydroxy-5-methylphenyl] methane, bis [3- (3,5-dimethyl-4-hydroxybenzyl) -4-hydroxy-5-ethylphenyl] methane, bis [3- (3,5-diethyl- 4-hydroxybenzyl) -4-hydroxy-5-methylphenyl] methane, bis [3- (3,5-diethyl-4-hydroxybenzyl) -4- Loxy-5-ethylphenyl] methane, bis [2-hydroxy-3- (3,5-dimethyl-4-hydroxybenzyl) -5-methylphenyl] methane, bis [2-hydroxy-3- (2-hydroxy-) 5-methylbenzyl) -5-methylphenyl] methane, bis [4-hydroxy-3- (2-hydroxy-5-methylbenzyl) -5-methylphenyl] methane, bis [2,5-dimethyl-3- ( Linear tetranuclear phenolic compounds such as 2-hydroxy-5-methylbenzyl) -4-hydroxyphenyl] methane;
2,4-bis [2-hydroxy-3- (4-hydroxybenzyl) -5-methylbenzyl] -6-cyclohexylphenol, 2,4-bis [4-hydroxy-3- (4-hydroxybenzyl) -5 Linear type 5 such as -methylbenzyl] -6-cyclohexylphenol and 2,6-bis [2,5-dimethyl-3- (2-hydroxy-5-methylbenzyl) -4-hydroxybenzyl] -4-methylphenol Linear polyphenol compounds such as nuclear phenol compounds;
Bis (2,3-trihydroxyphenyl) methane, bis (2,4-dihydroxyphenyl) methane, 2,3,4-trihydroxyphenyl-4'-hydroxyphenylmethane, 2- (2,3,4- Trihydroxyphenyl) -2- (2 ', 3', 4'-trihydroxyphenyl) propane, 2- (2,4-dihydroxyphenyl) -2- (2 ', 4'-dihydroxyphenyl) propane, 2- (4-hydroxyphenyl) -2- (4'-hydroxyphenyl) propane, 2- (3-fluoro-4-hydroxyphenyl) -2- (3'-fluoro-4'-hydroxyphenyl) propane, 2- ( 2,4-dihydroxyphenyl) -2- (4'-hydroxyphenyl) propane, 2- (2,3,4-trihydroxyphenyl) -2- (4'- Rokishifeniru) propane, 2- (2,3,4-hydroxyphenyl) -2- (4'-hydroxy-3 ', 5'-dimethylphenyl) bisphenol compounds such as propane;
1- [1- (4-hydroxyphenyl) isopropyl] -4- [1,1-bis (4-hydroxyphenyl) ethyl] benzene, 1- [1- (3-methyl-4-hydroxyphenyl) isopropyl]- Polynuclear branched compounds such as 4- [1,1-bis (3-methyl-4-hydroxyphenyl) ethyl] benzene;
Examples thereof include condensed phenol compounds such as 1,1-bis (4-hydroxyphenyl) cyclohexane.
These can be used alone or in combination of two or more.

  Examples of the naphthoquinone diazide sulfonic acid compound include naphthoquinone-1,2-diazide-5-sulfonic acid and naphthoquinone-1,2-diazide-4-sulfonic acid.

  In addition, other quinonediazide group-containing compounds such as orthobenzoquinonediazide, orthonaphthoquinonediazide, orthoanthraquinonediazide, or orthonaphthoquinonediazidesulfonic acid esters can be used. Further, orthoquinonediazidesulfonyl chloride and a compound having a hydroxyl group or an amino group (for example, phenol, p-methoxyphenol, dimethylphenol, hydroquinone, bisphenol A, naphthol, pyrocatechol, pyrogallol, pyrogallol monomethyl ether, pyrogallol-1,3 -Dimethyl ether, gallic acid, gallic acid esterified or etherified with some hydroxyl groups remaining, aniline, p-aminodiphenylamine, etc.) and the like can also be used. You may use these individually or in combination of 2 or more types.

  These quinonediazide group-containing compounds include, for example, a trisphenol type compound and naphthoquinone-1,2-diazide-5-sulfonyl chloride or naphthoquinone-1,2-diazide-4-sulfonyl chloride in a suitable solvent such as dioxane. , In the presence of an alkali such as triethanolamine, alkali carbonate, alkali hydrogen carbonate and the like, and can be produced by complete esterification or partial esterification. As the quinonediazide group-containing compound, a naphthoquinonediazidesulfonic acid ester is preferable.

  Content of a quinonediazide group containing compound is 10 mass%-40 mass% with respect to all the solid components, Preferably it is 20 mass%-30 mass%. By setting the content of the quinonediazide group-containing compound to 10% by mass or more, the resolution can be improved. Further, it is possible to reduce the amount of pattern loss after the pattern is formed. In addition, when the content of the quinonediazide group-containing compound is 40% by mass or less, appropriate sensitivity and transmittance can be imparted.

<Organic solvent>
The photosensitive resin composition of the present invention is preferably used as a solution dissolved in an appropriate organic solvent in order to improve applicability or adjust the viscosity.

  Organic solvents include benzene, toluene, xylene, methyl ethyl ketone, acetone, methyl isobutyl ketone, cyclohexanone, methanol, ethanol, propanol, butanol, hexanol, cyclohexanol, ethylene glycol, diethylene glycol, glycerin, ethylene glycol monomethyl ether, ethylene glycol monoethyl Ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, 3-methoxybutyl acetate (MA), 3-methoxybutanol (BM), 3-methyl- 3-methoxybu Le acetate, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether propionate, propylene glycol monoethyl ether propionate, methyl carbonate, ethyl carbonate, propyl carbonate, and carbonate-butyl or mixtures thereof and the like.

  Although the usage-amount of an organic solvent is not specifically limited, It is a density | concentration which can be apply | coated to a board | substrate etc., and is suitably set according to a coating film thickness. Specifically, it is preferable to use the photosensitive resin composition so that the solid content concentration is in the range of 10% by mass to 50% by mass, preferably 15% by mass to 35% by mass.

[Others]
The photosensitive resin composition according to the present invention may contain various additives such as a surfactant, a sensitizer, an antifoaming agent, and a crosslinking agent.

  The surfactant may be a conventionally known surfactant, and examples thereof include anionic, cationic, and nonionic compounds. Specific examples include X-70-090 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.). By adding the surfactant, the coating property and flatness can be improved.

  As the sensitizer, those used in conventionally known positive resists can be used. As said antifoamer, a conventionally well-known thing may be used and a silicone type compound and a fluorine-type compound are mentioned.

  Moreover, as a crosslinking agent, the polymeric compound which has an ethylenically unsaturated bond is mentioned. Among these compounds, monofunctional, bifunctional, or trifunctional or higher (meth) acrylates are preferably used from the viewpoint of good polymerizability and improved strength of the obtained spacer.

  Examples of the monofunctional (meth) acrylate include 2-hydroxyethyl (meth) acrylate, carbitol (meth) acrylate, isobornyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, and 2- (meth) acryloyloxyethyl. -2-hydroxypropyl phthalate and the like. As the commercial item, for example, Aronix M-101, M-111, M-114 (manufactured by Toa Gosei Chemical Co., Ltd.), KAYARAD TC-110S, TC-120S (manufactured by Nippon Kayaku Co., Ltd.) , Biscote 158, 2311 (manufactured by Osaka Organic Chemical Industry Co., Ltd.).

  Examples of the bifunctional (meth) acrylate include ethylene glycol (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, polypropylene glycol di (meth) acrylate, Examples include tetraethylene glycol di (meth) acrylate and bisphenoxyethanol full orange acrylate. As the commercial products, for example, Aronix M-210, M-240, M-6200 (manufactured by Toa Gosei Chemical Co., Ltd.), KAYARAD HDDA, HX-220, R-604 (Nippon Kayaku Co., Ltd.) ), Viscoat 260, 312 and 335HP (Osaka Organic Chemical Co., Ltd.).

  Examples of the trifunctional or higher functional (meth) acrylate include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, tri ((meth) acryloyloxyethyl) phosphate, and pentaerythritol tetra (meth) acrylate. , Dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and the like. As the commercial product, for example, Aronix M-309, M-400, M-402, M-405, M-450, M-7100, M-8030, M-8060 (Toa Gosei Chemical) Industrial Co., Ltd.), KAYARAD TMPTA, DPHA, DPCA-20, DPCA-30, DPCA-60, DPCA-60, DPCA-120 (manufactured by Nippon Kayaku Co., Ltd.), Biscote 295, 300, 360 , GPT, 3PA, 400 (produced by Osaka Organic Chemical Industry Co., Ltd.), and the like. These crosslinking agents are used alone or in combination.

<Preparation of positive photosensitive resin composition for spacer formation>
The photosensitive resin composition according to the present invention is prepared by, for example, mixing (dispersing and kneading) each component with a stirrer such as a roll mill, a ball mill, and a sand mill, and filtering with a filter such as a 5 μm membrane filter as necessary. can do.

<Spacer formation>
Next, a method for forming a spacer on a substrate using the photosensitive resin composition of the present invention will be described.

  First, after applying the photosensitive resin composition to the substrate, the solvent is removed by pre-baking to form a film. As the substrate, for example, a substrate made of glass, quartz, silicone, transparent resin or the like can be used. As a coating method, for example, various methods such as a spray method, a roll coating method, and a spin coating method can be used. Moreover, although the conditions of prebaking differ also with the kind of each component, a mixture ratio, etc., the conditions for about 1 minute-10 minutes at 80 to 120 degreeC are suitable.

  Next, the coating film is exposed to radiation such as ultraviolet rays and then developed with an alkali developer to remove unnecessary portions and form a predetermined pattern. Visible rays, ultraviolet rays, far ultraviolet rays, electron beams, X-rays, and the like can be used as radiation used for exposure.

  Examples of the alkali developer include inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, and ammonia; primary amines such as ethylamine and n-propylamine; diethylamine, di- Secondary amines such as n-propylamine; tertiary amines such as trimethylamine, methyldiethylamine, dimethylethylamine and triethylamine; alkanolamines such as dimethylethanolamine, methyldiethanolamine and triethanolamine; pyrrole, piperidine and N-methyl Cyclic tertiary amines such as piperidine, N-methylpyrrolidine, 1,8-diazabicyclo [5.4.0] -7-undecene, 1,5-diazabicyclo [4.3.0] -5-nonene; pyridine, Collidine, Luci Emissions, aromatic tertiary amines such as quinoline; tetramethylammonium hydroxide, the aqueous solution of quaternary ammonium salts such as tetraethyl ammonium hydroxide may be used. In addition, an appropriate amount of a water-soluble organic solvent such as methanol or ethanol and / or a surfactant can be added to the alkaline developer.

  The developing method may be any of a liquid piling method, a dipping method, a shower method, and the like, and the developing time is usually 10 seconds to 180 seconds. After alkali development, for example, washing with running water is performed, and the pattern is formed, for example, by drying with compressed air or compressed nitrogen.

  Next, the spacer can be formed by performing post-baking for a predetermined time at a predetermined temperature, for example, 150 ° C. to 250 ° C., using a heating device such as a hot plate or an oven.

  Since the photosensitive resin composition of the present invention is a positive type, spacers having different heights can be simultaneously formed by one exposure. As a pattern mask and exposure operation used for exposure, for example, there is a method of performing exposure once using one type of halftone mask having both a high spacer portion and a low spacer portion. Can be mentioned. Visible rays, ultraviolet rays, far ultraviolet rays, electron beams, X-rays, and the like can be used as radiation used for exposure.

  In addition, bumps can be formed simultaneously with the spacer formation. For example, a method of exposing once using a halftone mask having both a spacer part pattern and a bump part pattern at the time of the exposure can be mentioned. By forming the spacer and the bump at the same time, the productivity of the liquid crystal display can be improved. In this case, the unexposed portion becomes a spacer portion, the portion exposed through the halftone mask becomes the MVA bump portion (becomes a pattern portion lower than the spacer portion), and the exposed portion becomes a portion having no pattern. That is, a pattern having a step can be formed by a single exposure / development. On the other hand, when a negative photosensitive resin composition is used, it is difficult to form a pattern having a step by one exposure.

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

<Examples 1-7, Comparative Examples 1-3, 4, 5>
The following components were mixed to prepare a photosensitive resin composition.

  In Table 1, [] means parts by mass. A1 to A7 and A′1 to A′3 are polymers represented by the formula (I) and have the mass average molecular weights described in Table 2. In the formula (I), a1 and a2 at the right corner of the structural unit represent a molar ratio. A′5, B1, and S1 are as described below.

A′5: Novolak resin (molecular weight 5000, m / p cresol ratio = 50/50)
B1: 1- [1- (4-hydroxyphenyl) isopropyl] -4- [1,1-bis (4-hydroxyphenyl) ethyl] benzene-1,2-naphthoquinonediazide-5-sulfonic acid ester (esterification rate) 67%)
S1: 3-methoxybutyl acetate

The negative resist composition of Comparative Example 4 was obtained by adjusting the following components.
Alkali-soluble resin [100 parts by mass]: polymer represented by formula (II) (molecular weight: 15000). The number at the right corner of the structural unit in formula (II) indicates the molar ratio.
・ Dipentaerythritol hexaacrylate [30 parts by mass]
Initiator [10 parts by mass]: IRGACURE OXE02 (manufactured by Ciba Specialty Chemicals)
Organic solvent [300 parts by mass]: Mixed solvent of cyclohexanone / PGMEA = 1/2

<Evaluation>
<Dot pattern formation (developability)>
The photosensitive resin compositions of Examples 1 to 7 and Comparative Examples 1 to 5 were formed on a glass substrate (manufactured by Dow Corning: 0.7 mm × 150 mm (thickness × diameter)) to a film thickness of 2.6 μm. After coating with a spinner, it was dried on a hot plate at 110 ° C. for 120 seconds to obtain a coating film. This coating film was exposed using a mirror projection aligner (trade name: TME-150 RTO, manufactured by Topcon Corporation) through a positive mask pattern. Next, development was carried out by immersing in a NaOH / Na ₂ CO ₃ mixed aqueous solution (0.825 mass%) (developer) at 26 ° C. for 90 seconds, and unnecessary portions were removed after rinsing with pure water. . Thereafter, post-baking was performed at 230 ° C. for 20 minutes.

  As a result, with respect to the photosensitive resin compositions of Examples 1 to 7, Comparative Example 2, Comparative Example 4 and Comparative Example 5, a dot pattern with a diameter of 30 μm was formed. In Comparative Example 1 and Comparative Example 3, no dot pattern was formed due to poor development.

<Flexibility>
The dot patterns of Examples 1 to 7 and Comparative Examples 2 and 4 were subjected to a compression test under the following conditions, and “Total Deformation (hereinafter referred to as TD)” and “Elastic Recovery (hereinafter referred to as ER)” were performed. In search of flexibility. The evaluation results are shown in Table 3.
Device: MCT-W201 (manufactured by Shimadzu Corporation)
Maximum test force: 80mN
Minimum test force: 1.960 mN
Load speed: 4.413 mN / sec
Holding time: 5 seconds Measurement temperature: 23 ° C

TD (μm) means the amount of displacement from the original pattern height (2.6 μm).
TD = 2.6-(Pattern height when held at maximum test force for 5 seconds)
ER (%) indicates how much the height of the pattern has returned to TD.
ER (%) = {(pattern height after test−pattern height when held at maximum test force for 5 seconds) / (TD)} × 100

  In addition, ER shows that flexibility is so favorable that a value is large, Preferably it is 90% or more.

<Shape>
About the dot pattern of Examples 1-7 and Comparative Example 2 and Comparative Example 4, the cross-sectional shape was observed with SEM and evaluated according to the following criteria. Note that a good shape with a high taper angle means that the heat resistance is excellent (because the pattern does not sag during post-baking).

◎ The flatness of the upper surface of the dot pattern is good, and the taper angle is high.
○ The flatness of the upper surface of the dot pattern is good, and the taper angle is slightly low.
ΔTaper angle is low, and there is no flatness on the top surface of the dot pattern

  As can be seen from Table 3, the spacers of Examples 1 to 7 have a better ER of 90% or more than Comparative Examples 2, 4, and 5 and are excellent in shape (that is, in heat resistance). I understood it. This is very useful when forming the spacer and the MVA bump at the same time.

Claims (5)

A positive photosensitive resin composition for spacer formation comprising an alkali-soluble resin and a quinonediazide group-containing compound,
The alkali-soluble resin includes a structural unit (a1) represented by the following general formula (a-1) and a structural unit (a2) having a crosslinkable group, and the proportion of the structural unit (a1) is: A positive photosensitive resin composition for forming a spacer, wherein the positive photosensitive resin composition has a molar average molecular weight of 60,000 to 160000 and more than 40 mol% and 90 mol% or less.

[In the above general formula, R ⁰ represents a hydrogen atom or a methyl group, R ¹ represents a single bond or an alkylene group having 1 to 5 carbon atoms, R ² represents an alkyl group having 1 to 5 carbon atoms, and a represents Represents an integer of 1 to 5, b represents an integer of 0 to 4, and a + b is 5 or less. In the case where R ² is present 2 or more, these R ² may be the same or may be different from each other. ]   In the alkali-soluble resin, the proportion of the structural unit (a1) is 50 mol% to 80 mol%, and the proportion of the structural unit (a2) is 20 mol% to 50 mol%. The positive photosensitive resin composition for spacer formation according to claim 1.   The positive photosensitive resin composition for forming a spacer according to claim 1, wherein the crosslinkable group is an epoxy group.   The said alkali-soluble resin is a structural unit other than the said structural units (a1) and (a2), Comprising: The structural unit (a3) which does not have a carboxyl group, The any one of Claim 1 to 3 characterized by the above-mentioned. 2. A positive photosensitive resin composition for forming a spacer according to item 1.   5. The positive photosensitive resin composition for forming a spacer according to claim 4, wherein the proportion of the structural unit (a3) in the alkali-soluble resin is 1 mol% to 30 mol%.