JP5592064B2 - Positive resist composition - Google Patents

Description

  The present invention relates to a positive resist composition suitable for forming a thick resist film.

  With the progress of higher integration of LSI and ASIC, multi-pin thin film mounting for mounting LSI on electronic devices is required, and attention is paid to bare chip mounting by TCP method or flip chip method. In such a multi-pin mounting, it is necessary to dispose a protruding electrode with a height of 20 μm or more, called a bump as a connection terminal, on the substrate with high precision. In the future, bumps corresponding to further miniaturization of LSIs High accuracy is required.

  In order to form bumps, a positive resist composition containing an alkali-soluble novolak resin and a quinonediazide group-containing compound that is a photosensitizer has been conventionally used. In order to form the bumps, for example, a resist film having a thickness of about 20 μm is first formed on the support, and a resist pattern is formed by exposure and development through a predetermined mask pattern. Thereafter, a plating process such as gold, copper, or solder is performed to remove the surrounding resist pattern.

  In this positive resist composition, for example, in the case of bumps, the resist film does not crack during plating treatment or in subsequent water washing, and in the case of TCP, even on a flexible tape substrate. Similarly, it is required that the resist film does not crack. In addition, the verticality of the resist pattern sidewalls is good, the resolution is high as the pitch of bumps is narrowed, and no resist residue is generated after development.

In order to prevent the occurrence of cracks, for example, Patent Document 1 discloses a positive resist composition for a thick film containing an alkali-soluble novolak resin, a quinonediazide group-containing compound, and an alkali-soluble acrylic resin as a plasticizer. Have been described.
Japanese Patent No. 3710717

  However, when such a conventional alkali-soluble acrylic resin is used as a plasticizer, a mass-average molecular weight (in terms of polystyrene by gel permeation chromatography (GPC) measurement is used to obtain sufficient crack resistance. The same applies in this specification). .) Needs to be over 200,000, and as a result, there are problems that the resist pattern shape deteriorates, the resolution decreases, and resist residues are generated during development.

  The present invention has been made in view of such conventional problems, and is a positive type that has improved crack resistance while suppressing resist pattern shape deterioration, resolution degradation, and generation of resist residues during development. It is an object to provide a resist composition.

  The inventors of the present invention have made extensive studies to achieve the above object. As a result, it has been found that the above-mentioned problems can be solved by using an alkali-soluble acrylic resin having a specific structural unit as a plasticizer, and the present invention has been completed. Specifically, the present invention provides the following.

［一般式（Ｂ−１）中、Ｒ^１ｂは水素原子又はメチル基を示し、Ｒ^２ｂは置換基を有していてもよい炭素数５以上の直鎖状又は分岐鎖状のアルキル基を示す。］ The first aspect of the present invention comprises (A) an alkali-soluble novolak resin, (B) an alkali-soluble acrylic resin, and (C) a photosensitizer, and the (B) alkali-soluble acrylic resin is represented by the following general formula (B- A positive resist composition comprising (b1) a structural unit represented by 1).

[In General Formula (B-1), R ^1b represents a hydrogen atom or a methyl group, and R ^2b represents a linear or branched alkyl group having 5 or more carbon atoms which may have a substituent. . ]

  The second aspect of the present invention is: (A ′) an alkali-soluble novolak resin in which a part of the hydrogen atoms of the total phenolic hydroxyl group is substituted with a 1,2-naphthoquinonediazidosulfonyl group, and (B) an alkali-soluble acrylic resin. And the (B) alkali-soluble acrylic resin has a structural unit (b1) represented by the general formula (B-1).

  According to the present invention, crack resistance can be enhanced while suppressing the deterioration of the resist pattern shape, the resolution, and the generation of resist residues during development.

≪Positive resist composition≫
The positive resist composition according to the first aspect of the present invention comprises (A) an alkali-soluble novolak resin (hereinafter also referred to as “component (A)”), (B) an alkali-soluble acrylic resin (hereinafter referred to as “(B)”. And (C) a photosensitive agent (hereinafter also referred to as “component (C)”).
Further, the positive resist composition according to the second aspect of the present invention comprises (A ′) an alkali-soluble novolak resin in which a part of the hydrogen atoms of the total phenolic hydroxyl group is substituted with a 1,2-naphthoquinonediazidesulfonyl group ( Hereinafter, it is also referred to as “component (A ′)”) and (B) an alkali-soluble acrylic resin. In this second embodiment, (C) the photosensitive agent is an optional component.
Hereinafter, each component contained in the positive resist composition will be described in detail.

<(A) Alkali-soluble novolak resin>
The component (A) contained in the positive resist composition according to the present invention is not particularly limited, but an aromatic compound having a phenolic hydroxyl group (hereinafter simply referred to as “phenols”) and an aldehyde are acidified. Those obtained by addition condensation under a catalyst are preferred.

  Examples of the phenols include cresols such as phenol, o-cresol, m-cresol, and p-cresol; 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, Xylenols such as 3,4-xylenol and 3,5-xylenol; ethylphenols such as o-ethylphenol, m-ethylphenol and p-ethylphenol, 2-isopropylphenol, 3-isopropylphenol and 4-isopropylphenol Alkylphenols such as o-butylphenol, m-butylphenol, p-butylphenol and p-tert-butylphenol; trialkylphenols such as 2,3,5-trimethylphenol and 3,4,5-trimethylphenol; resorcinol; Polyhydric phenols such as tecol, hydroquinone, hydroquinone monomethyl ether, pyrogallol, phloroglicinol; alkyl polyhydric phenols such as alkylresorcin, alkylcatechol, alkylhydroquinone (all alkyl groups have 1 to 4 carbon atoms) , Α-naphthol, β-naphthol, hydroxydiphenyl, bisphenol A and the like. These phenols can be used individually or in combination of 2 or more types.

  Among these phenols, m-cresol and p-cresol are preferable, and it is more preferable to use m-cresol and p-cresol in combination. Various characteristics such as sensitivity and heat resistance as the positive resist composition can be adjusted by adjusting the blending ratio of the two. The blending ratio of m-cresol and p-cresol is not particularly limited, but m-cresol / p-cresol = 3/7 to 8/2 (mass ratio) is preferable. Sensitivity can be improved by setting the ratio of m-cresol to 3/7 or more, and heat resistance can be improved by setting it to 8/2 or less.

  Examples of the aldehydes include formaldehyde, paraformaldehyde, furfural, benzaldehyde, nitrobenzaldehyde, and acetaldehyde. These aldehydes can be used alone or in combination of two or more.

  Examples of the acid catalyst include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and phosphorous acid; organic acids such as formic acid, oxalic acid, acetic acid, diethylsulfuric acid, and paratoluenesulfonic acid; metal salts such as zinc acetate Etc. These acid catalysts can be used alone or in combination of two or more.

  The mass average molecular weight of the component (A) is preferably 1000 to 50000 from the viewpoints of developability, resolution, and plating solution resistance of the positive resist composition.

  The component (A) is preferably a fractionation resin in which the content of the low nuclei is reduced to 80% by mass or less, more preferably 50% by mass or less before the fractionation by the fractionation process. Here, the low nuclear body means the above-described phenols, that is, a phenol monomer, a dimer obtained from two molecules of the phenol monomer, a trimer obtained from three molecules of the phenol monomer, and the like. By using such a separation resin, the perpendicularity of the cross-sectional shape of the resist pattern is further improved, resist residues (scum) are hardly generated during development, and resolution is improved. Moreover, there exists a tendency which is excellent in heat resistance, and it is preferable.

  The fractionation treatment can be performed by, for example, the following well-known fractional precipitation treatment. First, as described above, after an addition condensation reaction between phenols and aldehydes, the obtained addition condensation product (novolak resin) is dissolved in a polar solvent, and water, heptane, hexane is added to this solution. Add a poor solvent such as pentane or cyclohexane. At this time, since the low nuclei have a relatively high solubility, they remain dissolved in the poor solvent, and thus a fractionated resin with a reduced content of the low nuclei can be obtained by filtering the precipitate. .

  Examples of the polar solvent include alcohols such as methanol and ethanol; ketones such as acetone and methyl ethyl ketone; glycol ether esters such as ethylene glycol monoethyl ether acetate; and cyclic ethers such as tetrahydrofuran.

  (A) Content of the low nucleus in a component can be confirmed from the result of GPC measurement. That is, from the GPC chart, the molecular weight distribution of the synthesized phenol novolak resin can be confirmed, and the content can be calculated by measuring the intensity ratio of the peak corresponding to the elution time of the low-nuclear body. . In addition, since the elution time of a low nuclear body changes with measuring means, identification of a column, an eluent, flow volume, temperature, a detector, sample concentration, injection amount, a measuring device, etc. is important.

  The dispersity [mass average molecular weight (Mw) / number average molecular weight (Mn)] of the fractional resin is preferably 3.0 or less, and more preferably 2.2 to 2.8.

<(A ′) Alkali-soluble novolak resin in which a part of hydrogen atoms of all phenolic hydroxyl groups is substituted with 1,2-naphthoquinonediazidesulfonyl group>
The component (A ′) contained in the positive resist composition according to the present invention is not particularly limited, but some of the hydrogen atoms of all phenolic hydroxyl groups contained in the component (A) are 1,2-naphtho. Those substituted with a quinonediazidosulfonyl group are preferred. When the component (A ′) is used, the sensitivity of the positive resist composition can be further improved because the naphthoquinonediazidesulfonyl group having a small amount of the component (A ′) itself has photosensitivity.

  Substitution with a 1,2-naphthoquinonediazidesulfonyl group can be performed by an esterification reaction of the component (A) with a 1,2-naphthoquinonediazidesulfonic acid compound. Examples of the 1,2-naphthoquinone diazide sulfonic acid compound include halides of quinone diazide compounds such as 1,2-naphthoquinone diazide-4-sulfonic acid chloride and 1,2-naphthoquinone diazide-5-sulfonic acid chloride.

  The ratio of substitution with 1,2-naphthoquinonediazidosulfonyl group, that is, the reaction rate of the esterification reaction is preferably 2 to 10 mol%, more preferably 3 to 7 mol%, further preferably 3 to 5 mol%. By setting the reaction rate to 2 mol% or more, the film loss of the unexposed portion can be suppressed, and by setting it to 10 mol% or less, the sensitivity is improved and the perpendicularity of the resist pattern cross-sectional shape is improved. be able to.

［一般式（Ｂ−１）中、Ｒ^１ｂは水素原子又はメチル基を示し、Ｒ^２ｂは置換基を有していてもよい炭素数５以上の直鎖状又は分岐鎖状のアルキル基を示す。］ <(B) Alkali-soluble acrylic resin>
The component (B) contained in the positive resist composition according to the present invention has a structural unit (b1) represented by the following general formula (B-1).

[In General Formula (B-1), R ^1b represents a hydrogen atom or a methyl group, and R ^2b represents a linear or branched alkyl group having 5 or more carbon atoms which may have a substituent. . ]

In the general formula (B-1), the carbon number of the alkyl group represented by ^{R 2} is preferably 5 to 15, 7 to 10 is more preferable. Examples of such an alkyl group include a linear alkyl group such as an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group, and an n-decyl group; an isopentyl group, Neopentyl group, isohexyl group, neohexyl group, isoheptyl group, neoheptyl group, 2-ethylpentyl group, isooctyl group, neooctyl group, 2-ethylhexyl group, isononyl group, neononyl group, 2-ethylheptyl group, isodecyl group, neodecyl group, Examples thereof include branched alkyl groups such as 2-ethyloctyl group. Among these, a branched alkyl group is preferable from the viewpoint of crack resistance.

Examples of the substituent that the alkyl group represented by R ² may have include a hydroxyl group, an amino group, and carboxyl.

  The proportion of the structural unit (b1) in the component (B) is preferably 10 to 90% by mass, and more preferably 15 to 50% by mass. (B1) By setting the proportion of the structural unit to 10% by mass or more, crack resistance can be enhanced while suppressing the deterioration of the resist pattern shape, the resolution, and the generation of resist residues during development. By setting it as the mass% or less, film | membrane slip and the fall of resolution can be suppressed.

  Moreover, it is preferable that (B) component has the structural unit induced | guided | derived from the polymeric compound which has developability (b2) carboxyl group. (B2) As structural units, monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid; dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid; 2-methacryloyloxyethyl succinic acid, 2-methacryloyloxyethyl maleic acid Methacrylic acid derivatives having a carboxyl group and an ester bond, such as 2-methacryloyloxyethyl phthalic acid and 2-methacryloyloxyethyl hexahydrophthalic acid. Of these, acrylic acid and methacrylic acid are preferable. These (b2) structural units can be used individually or in combination of 2 or more types.

  (B) When a component has (b2) structural unit, it is preferable that the ratio is 2-50 mass%, and it is more preferable that it is 5-40 mass%. (B2) By making the proportion of the structural unit 2% by mass or more, the developability can be improved, and by setting it to 50% by mass or less, it is possible to suppress the decrease in the remaining film rate and improve the plating resistance. it can.

  Furthermore, the component (B) may have a structural unit derived from another polymerizable compound in order to adjust physical and chemical properties. Examples of such polymerizable compounds include (meth) acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate; phenyl (meth) acrylate, benzyl (meth) acrylate, and the like. (Meth) acrylic acid aryl esters; dicarboxylic acid diesters such as diethyl maleate and dibutyl fumarate; vinyl group-containing aromatic compounds such as styrene and α-methylstyrene; vinyl group-containing aliphatic compounds such as vinyl acetate; Conjugated diolefins such as butadiene and isoprene; Nitrile group-containing polymerizable compounds such as acrylonitrile and methacrylonitrile; Chlorine-containing polymerizable compounds such as vinyl chloride and vinylidene chloride; Amide bond-containing polymerizable compounds such as acrylamide and methacrylamide Is It is. These structural units can be used individually or in combination of 2 or more types.

  The proportion of the structural unit derived from the other polymerizable compound in component (B) is preferably less than 50% by weight, and more preferably less than 40% by weight.

Examples of the polymerization solvent used when the component (B) is synthesized include alcohols such as ethanol and diethylene glycol; alkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, and diethylene glycol ethyl methyl ether; ethylene Alkyl ether acetates of polyhydric alcohols such as glycol ethyl ether acetate and propylene glycol methyl ether acetate; Aromatic hydrocarbons such as toluene and xylene; Ketones such as acetone and methyl isobutyl ketone; Esters such as ethyl acetate and butyl acetate And the like.
Moreover, as a polymerization catalyst used when synthesize | combining (B) component, for example, azo compounds, such as 2,2'-azobisisobutyronitrile; Organic, such as benzoyl peroxide and di-tert- butyl peroxide A peroxide etc. are mentioned.

  The weight average molecular weight of the component (B) is preferably 10,000 to 200,000, more preferably 50,000 to 150,000, from the viewpoints of the resist pattern shape, resolution, resist residue during development, and crack resistance. In the conventional alkali-soluble acrylic resin, it was necessary to make the mass average molecular weight more than 200,000 in order to obtain sufficient crack resistance, but the component (B) in the present invention has the above-mentioned (b1) structural unit. Even if the mass average molecular weight is 100,000 or less, sufficient crack resistance is exhibited.

  Moreover, it is preferable that the glass transition point (Tg) of (B) component is -20 degrees C or less. By setting the glass transition point to −20 ° C. or lower, the flexibility of the resist film can be increased and the crack resistance can be improved. Since the component (B) of the present invention has the structural unit (b1), the glass transition point can be lowered to -20 ° C or lower. The lower limit of the glass transition point is preferably -100 ° C.

  Moreover, it is preferable that the acid value of (B) component is 20 mgKOH / g or more. By making the acid value 20 mgKOH / g or more, developability can be improved. The upper limit of this acid value is preferably 60 mgKOH / g.

  The content of the component (B) is preferably 5 to 50 parts by mass, and more preferably 10 to 40 parts by mass with respect to 100 parts by mass of the component (A) or the component (A ′). By setting the content to 5 parts by mass or more, the plating solution resistance can be improved, and by setting the content to 50 parts by mass or less, the strength of the formed resist film is increased and the resolution is improved.

<(C) Photosensitive agent>
Although it does not specifically limit as (C) component contained in the positive resist composition which concerns on this invention, A quinonediazide group containing compound is preferable. Examples of the quinonediazide group-containing compound include 2,3,4-trihydroxybenzophenone, 2,4,4′-trihydroxybenzophenone, 2,4,6-trihydroxybenzophenone, and 2,3,6-trihydroxybenzophenone. 2,3,4-trihydroxy-2'-methylbenzophenone, 2,3,4,4'-tetrahydroxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 2,3', 4 4 ′, 6-pentahydroxybenzophenone, 2,2 ′, 3,4,4′-pentahydroxybenzophenone, 2,2 ′, 3,4,5-pentahydroxybenzophenone, 2,3 ′, 4,4 ′, Polyhydroxybenzoes such as 5 ′, 6-hexahydroxybenzophenone and 2,3,3 ′, 4,4 ′, 5′-hexahydroxybenzophenone Phenones; bis (2,4-dihydroxyphenyl) methane, bis (2,3,4-trihydroxyphenyl) methane, 2- (4-hydroxyphenyl) -2- (4′-hydroxyphenyl) propane, 2- (2,4-dihydroxyphenyl) -2- (2 ′, 4′-dihydroxyphenyl) propane, 2- (2,3,4-trihydroxyphenyl) -2- (2 ′, 3 ′, 4′-tri Hydroxyphenyl) propane, 4,4 ′-{1- [4- [2- (4-hydroxyphenyl) -2-propyl] phenyl] ethylidene} bisphenol, 3,3′-dimethyl- {1- [4- [ Bis [(poly) hydroxyphenyl] alkanes such as 2- (3-methyl-4-hydroxyphenyl) -2-propyl] phenyl] ethylidene} bisphenol; tris (4-hydroxy Phenyl) methane, bis (4-hydroxy-3,5-dimethylphenyl) -4-hydroxyphenylmethane, bis (4-hydroxy-2,5-dimethylphenyl) -4-hydroxyphenylmethane, bis (4-hydroxy- 3,5-dimethylphenyl) -2-hydroxyphenylmethane, bis (4-hydroxy-2,5-dimethylphenyl) -2-hydroxyphenylmethane, bis (4-hydroxy-2,5-dimethylphenyl) -3, Tris (hydroxyphenyl) methanes such as 4-dihydroxyphenylmethane and bis (4-hydroxy-3,5-dimethylphenyl) -3,4-dihydroxyphenylmethane or methyl-substituted products thereof; bis (3-cyclohexyl-4- Hydroxyphenyl) -3-hydroxyphenylmethane, bis (3-cycl Rohexyl-4-hydroxyphenyl) -2-hydroxyphenylmethane, bis (3-cyclohexyl-4-hydroxyphenyl) -4-hydroxyphenylmethane, bis (5-cyclohexyl-4-hydroxy-2-methylphenyl) -2- Hydroxyphenylmethane, bis (5-cyclohexyl-4-hydroxy-2-methylphenyl) -3-hydroxyphenylmethane, bis (5-cyclohexyl-4-hydroxy-2-methylphenyl) -4-hydroxyphenylmethane, bis ( 3-cyclohexyl-2-hydroxyphenyl) -3-hydroxyphenylmethane, bis (5-cyclohexyl-4-hydroxy-3-methylphenyl) -4-hydroxyphenylmethane, bis (5-cyclohexyl-4-hydroxy-3- Methylpheny ) -3-hydroxyphenylmethane, bis (5-cyclohexyl-4-hydroxy-3-methylphenyl) -2-hydroxyphenylmethane, bis (3-cyclohexyl-2-hydroxyphenyl) -4-hydroxyphenylmethane, bis ( 3-cyclohexyl-2-hydroxyphenyl) -2-hydroxyphenylmethane, bis (5-cyclohexyl-2-hydroxy-4-methylphenyl) -2-hydroxyphenylmethane, bis (5-cyclohexyl-2-hydroxy-4-) Bis (cyclohexylhydroxyphenyl) (hydroxyphenyl) methanes such as methylphenyl) -4-hydroxyphenylmethane or methyl-substituted products thereof; phenol, p-methoxyphenol, dimethylphenol, hydroquinone, naphthol, pyrocate , Pyrogallol, pyrogallol monomethyl ether, pyrogallol-1,3-dimethyl ether, gallic acid, aniline, p-aminodiphenylamine, compounds having a hydroxyl group or amino group such as 4,4′-diaminobenzophenone; novolak, pyrogallol-acetone resin , Homopolymers of p-hydroxystyrene or copolymers with monomers copolymerizable therewith, and naphthoquinone-1,2-diazide-5-sulfonic acid, naphthoquinone-1,2-diazide-4-sulfonic acid, ortho Examples include complete ester compounds, partial ester compounds, amidated products, partially amidated products, and the like with quinonediazide group-containing sulfonic acids such as anthraquinone diazide sulfonic acid. These photosensitizers can be used alone or in combination of two or more.

［一般式（Ｃ−１）、（Ｃ−２）中、Ｒ^１ｃ〜Ｒ^７ｃはそれぞれ独立して水素原子、置換基を有していてもよい炭素数１〜５のアルキル基、置換基を有していてもよい炭素数４〜８のシクロアルキル基を示す。］ Among these, quinonediazide sulfonic acid esters of compounds represented by the following general formulas (C-1) and (C-2) are preferable.

[In General Formulas (C-1) and (C-2), R ^{1c to} R ^7c each independently represent a hydrogen atom or an optionally substituted alkyl group or substituent having 1 to 5 carbon atoms. The C4-C8 cycloalkyl group which you may have is shown. ]

Among the quinonediazide sulfonates of the compounds represented by the general formulas (C-1) and (C-2), the quinonediazide sulfonate of the compound represented by the following structural formula (C-3) is particularly preferable.

  Here, in the compounds represented by the general formulas (C-1), (C-2) and the structural formula (C-3), the naphthoquinone-1,2-diazide-sulfonyl group is located at the 4-position or the 5-position. Those having a sulfonyl group bonded thereto are preferred. These compounds dissolve well in a solvent usually used when the composition is used as a solution, and have good compatibility with the component (A). When used as a photosensitizer for a positive resist composition, In addition to excellent image contrast and cross-sectional shape with sensitivity, heat resistance, and a composition that does not generate foreign matter when used as a solution.

Examples of the compound represented by the general formula (C-1) include 1-hydroxy-4- [1,1-bis (4-hydroxyphenyl) ethyl] benzene and naphthoquinone-1,2-diazide-sulfonyl chloride. It can be produced by condensing in a solvent such as dioxane in the presence of an alkali such as triethanolamine, alkali carbonate, alkali hydrogencarbonate, etc., and complete esterification or partial esterification. The compound represented by the general formula (C-2) is, for example, 1- [1- (4-hydroxyphenyl) isopropyl] -4- [1,1-bis (4-hydroxyphenyl) ethyl] benzene and By condensing naphthoquinone-1,2-diazide-sulfonyl chloride in a solvent such as dioxane in the presence of an alkali such as triethanolamine, alkali carbonate, alkali hydrogencarbonate, etc., to complete esterification or partial esterification Can be manufactured.
The naphthoquinone-1,2-diazide-sulfonyl chloride is preferably naphthoquinone-1,2-diazide-4-sulfonyl chloride or naphthoquinone-1,2-diazide-5-sulfonyl chloride.

When the component (A) is used as the base resin, the content of the component (C) is preferably 5 to 100 parts by mass and more preferably 10 to 50 parts by mass with respect to 100 parts by mass of the component (A). preferable. By setting the content to 5 parts by mass or more, a desired resist pattern can be obtained. By setting the content to 50 parts by mass or less, sensitivity can be maintained.
On the other hand, when the component (A ′) is used as the base resin, the component (C) is not essential, but when the component (C) is contained, 1 to 30 parts by mass with respect to 100 parts by mass of the component (A ′). It is preferable that it is 5-20 mass parts.

<Other ingredients>
The positive resist composition according to the present invention is preferably used in the form of a solution by dissolving the above components in an appropriate solvent. Examples of such solvents include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol alkyl ethers such as ethylene glycol monobutyl ether; diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, Diethylene glycol dialkyl ethers such as diethylene glycol dibutyl ether; ethylene glycol alkyl ether acetates such as methyl cellosolve acetate and ethyl cellosolve acetate; propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether Propylene glycol alkyl ether acetates such as cetate; ketones such as acetone, methyl ethyl ketone, cyclohexanone and methyl amyl ketone; aromatic hydrocarbons such as toluene and xylene; cyclic ethers such as dioxane; methyl 2-hydroxypropionate; Ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl oxyacetate, methyl 2-hydroxy-3-methylbutanoate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl Examples thereof include esters such as acetate, ethyl formate, ethyl acetate, butyl acetate, methyl acetoacetate and ethyl acetoacetate. These solvents can be used alone or in combination of two or more.
The amount of the solvent used is preferably such that the solid concentration in the positive resist composition is 20 to 65% by mass in order to obtain a film thickness of 3 μm or more by using, for example, a spin coating method.

In addition, the positive resist composition according to the present invention may contain a surfactant in order to improve coating properties, antifoaming properties, leveling properties and the like. Examples of the surfactant include BM-1000, BM-1100 (manufactured by BM Chemie), MegaFuck F142D, F172, F173, F183 (manufactured by Dainippon Ink and Chemicals), Florard FC-135, FC -170C, FC-430, FC-431 (Sumitomo 3M), Surflon S-112, S-113, S-131, S-141, S-145 (Asahi Glass), SH Commercially available fluorine-based surfactants such as -28PA, -190, -193, SZ-6032, and SF-8428 (manufactured by Toray Silicone Co., Ltd.) can be used.
It is preferable that content of surfactant is 5 mass parts or less with respect to 100 mass parts of (A) component or (A ') component.

Further, the positive resist composition according to the present invention may contain an adhesion assistant in order to improve the adhesion with the substrate. A functional silane coupling agent is preferred as the adhesion assistant. Here, the functional silane coupling agent means a silane coupling agent having a reactive substituent such as a carboxyl group, a methacryloyl group, an isocyanate group, and an epoxy group. Specific examples include trimethoxysilylbenzoic acid, γ- Examples include methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, vinyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and the like.
The content of the adhesion assistant is preferably 20 parts by mass or less with respect to 100 parts by mass of the component (A) or the component (A ′).

  Further, the positive resist composition according to the present invention finely adjusts the solubility in an alkali developer, so that acetic acid, propionic acid, n-butyric acid, isobutyric acid, n-valeric acid, isovaleric acid, benzoic acid, Monocarboxylic acids such as cinnamic acid; lactic acid, 2-hydroxybutyric acid, 3-hydroxybutyric acid, salicylic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid, 2-hydroxycinnamic acid, 3-hydroxycinnamic acid, 4-hydroxycinnamic acid Hydroxy monocarboxylic acids such as acid, 5-hydroxyisophthalic acid and syringic acid; oxalic acid, succinic acid, glutaric acid, adipic acid, maleic acid, itaconic acid, hexahydrophthalic acid, phthalic acid, isophthalic acid, terephthalic acid, 1 , 2-cyclohexanedicarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, trimellitic acid, pyromellitic Polyvalent carboxylic acids such as cyclopentanetetracarboxylic acid, butanetetracarboxylic acid, 1,2,5,8-naphthalenetetracarboxylic acid; itaconic anhydride, succinic anhydride, citraconic anhydride, dodecenyl succinic anhydride, tricarbanilic anhydride , Maleic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hymic anhydride, 1,2,3,4, -butanetetracarboxylic acid, cyclopentanetetracarboxylic dianhydride, phthalic anhydride, pyrone anhydride It may contain acid anhydrides such as merit acid, trimellitic anhydride, benzophenone tetracarboxylic anhydride, ethylene glycol bis trimellitic anhydride, and glycerin tris anhydrous trimellitate. Further, N-methylformamide, N, N-dimethylformamide, N-methylformanilide, N-methylacetamide, N, N-dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, benzylethyl ether, dihexyl ether, acetonylacetone , Isophorone, caproic acid, caprylic acid, 1-octanol, 1-nonanol, benzyl alcohol, benzyl acetate, ethyl benzoate, diethyl oxalate, diethyl maleate, γ-butyrolactone, ethylene carbonate, propylene carbonate, phenyl cellosolve acetate, etc. A high boiling point solvent may be contained. The content of the compound for finely adjusting the solubility in the alkali developer can be adjusted according to the application and application method, and is not particularly limited as long as the composition can be mixed uniformly. However, it is preferably 60% by weight or less, more preferably 40% by weight or less, based on the positive resist composition.

  Furthermore, the positive resist composition according to the present invention may contain a filler, a colorant, a viscosity modifier and the like. Examples of the filler include silica, alumina, talc, bentonite, zirconium silicate, and powdered glass. As colorants, extender pigments such as alumina white, clay, barium carbonate, barium sulfate, etc .; inorganics such as zinc white, lead white, yellow lead, red lead, ultramarine, bitumen, titanium oxide, zinc chromate, bengara, carbon black Pigments; organic pigments such as brilliant carmine 6B, permanent red 6B, permanent red R, benzidine yellow, phthalocyanine blue, and phthalocyanine green; basic dyes such as magenta and rhodamine; direct dyes such as direct scarlet and direct orange; Examples include acid dyes such as yellow. Examples of the viscosity modifier include bentonite, silica gel, and aluminum powder. The content of these additives is preferably 50% by weight or less with respect to the positive resist composition.

<Preparation of positive resist composition>
When the positive resist composition according to the present invention does not contain a filler or a pigment, it can be prepared by mixing and stirring by a usual method. Moreover, when it contains a filler and a pigment, it can prepare by disperse | distributing and mixing using dispersers, such as a dissolver, a homogenizer, and a 3 roll mill. If necessary, it may be further filtered using a mesh, a membrane filter or the like.

≪Usage of positive resist composition≫
The positive resist composition according to the present invention is suitable for a thick film, but its use mode is not limited to this. For example, a protective film or a semiconductor during etching of various substrates such as copper, chromium, iron, glass substrate, etc. It can also be used when forming a production resist film. In the case of forming a resist film using the positive resist composition according to the present invention, the film thickness is preferably 1 to 100 μm, more preferably 3 to 40 μm, further preferably 20 to 30 μm.

  Bump formation using the positive resist composition according to the present invention is performed, for example, as follows.

  First, the positive resist composition prepared as described above is applied to a substrate having a predetermined wiring pattern with a film thickness of 15 to 100 μm, preferably 20 to 40 μm, and the solvent is removed by heating (pre-baking). Then, a desired resist film is formed. Examples of the coating method on the substrate include a spin coating method, a roll coating method, a screen printing method, and an applicator method. Prebaking conditions vary depending on the type, content, coating thickness, and the like of each component in the positive resist composition, but are usually 70 to 130 ° C., preferably 80 to 120 ° C., and about 2 to 60 minutes.

Next, the obtained resist film is exposed to radiation, for example, ultraviolet rays having a wavelength of 300 to 500 nm or visible light through a mask having a predetermined pattern, so that only the wiring pattern portion on which the bump is formed is exposed. Examples of these radiation sources include a low-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a metal halide lamp, and an argon gas laser. Here, the radiation means ultraviolet rays, visible rays, far ultraviolet rays, X-rays, electron beams, and the like. The amount of radiation irradiation varies depending on the type and content of each component in the positive resist composition, the thickness of the resist film, and the like, but is, for example, 100 to 2000 mJ / cm ² when using an ultrahigh pressure mercury lamp.

  Next, the resist film after irradiation with radiation is developed using an alkali developer to form a resist pattern. Examples of the alkali developer include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, Dimethylethanolamine, triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, pyrrole, piperidine, 1,8-diazabicyclo [5,4,0] -7-undecene, 1,5-diazabicyclo [4,3, 0] -5-nonane and the like. The development time varies depending on the type and content of each component in the positive resist composition, the film thickness of the resist film, and the like, but is usually 1 to 30 minutes. Further, the developing method may be any of a liquid piling method, a dipping method, a paddle method, a spray developing method and the like. After the development, washing with running water is performed for 30 to 90 seconds and air-dried using an air gun or the like, or dried in an oven.

  Next, bumps are formed by embedding a conductor such as metal in the non-resist portion (portion removed with the alkali developer) of the obtained resist pattern by plating. The plating method is not particularly limited, and various conventionally known methods can be employed. As the plating solution, a solder plating solution, a copper plating solution, a gold plating solution, or a nickel plating solution is preferable. The remaining resist pattern is finally removed using a stripping solution or the like according to a conventional method.

  Examples of the present invention will be described below, but the scope of the present invention is not limited to these examples.

<Synthesis of alkali-soluble novolac resin>
(Synthesis Example 1)
m-cresol and p-cresol are mixed at m-cresol / p-cresol = 60/40 (mass ratio), formalin is added thereto, and cresol novolac resin is added and condensed by an ordinary method using an oxalic acid catalyst. Got. The resin was subjected to a fractionation treatment to cut a low molecular region to obtain a novolak resin A1 having a mass average molecular weight of 15000.

<Synthesis of alkali-soluble acrylic resin>
(Synthesis Example 2)
A flask equipped with a stirrer, a reflux device, a thermometer, and a dropping tank was purged with nitrogen, and then 200 g of propylene glycol methyl ether acetate was charged as a solvent, and stirring was started. Thereafter, the temperature of the solvent was raised to 80 ° C. A dropping tank was charged with 125 g of 2-methoxyethyl acrylate, 30 g of methacrylic acid, 45 g of isononyl acrylate, 0.5 g of 2,2′-azobisisobutyronitrile as a polymerization catalyst, and stirred until the polymerization catalyst was dissolved. The solution was uniformly dropped into the flask for 3 hours, followed by polymerization at 80 ° C. for 5 hours. Then, it cooled to room temperature and obtained acrylic resin B1 with a mass mean molecular weight 96000 and a glass transition point -42 degreeC.

(Synthesis Example 3)
A flask equipped with a stirrer, a reflux device, a thermometer, and a dropping tank was purged with nitrogen, and then 200 g of propylene glycol methyl ether acetate was charged as a solvent, and stirring was started. Thereafter, the temperature of the solvent was raised to 80 ° C. A dropping tank was charged with 30 g of methacrylic acid, 170 g of isononyl acrylate, and 0.5 g of 2,2′-azobisisobutyronitrile as a polymerization catalyst. After stirring until the polymerization catalyst was dissolved, this solution was placed in the flask for 3 hours. The solution was dropped uniformly, and then polymerization was carried out at 80 ° C. for 5 hours. Then, it cooled to room temperature and obtained acrylic resin B2 with a mass average molecular weight 95000 and a glass transition point -70 degreeC.

(Synthesis Example 4)
A flask equipped with a stirrer, a reflux device, a thermometer, and a dropping tank was purged with nitrogen, and then 200 g of propylene glycol methyl ether acetate was charged as a solvent, and stirring was started. Thereafter, the temperature of the solvent was raised to 80 ° C. In a dropping tank, 125 g of 2-methoxyethyl acrylate, 30 g of methacrylic acid, 45 g of lauryl methacrylate and 0.5 g of 2,2′-azobisisobutyronitrile as a polymerization catalyst were added and stirred until the polymerization catalyst was dissolved. Was uniformly dropped into the flask for 3 hours, followed by polymerization at 80 ° C. for 5 hours. Then, it cooled to room temperature and obtained acrylic resin B3 with a mass mean molecular weight 94000 and a glass transition point -25 degreeC.

(Comparative Synthesis Example 1)
A flask equipped with a stirrer, a reflux device, a thermometer, and a dropping tank was purged with nitrogen, and then 200 g of propylene glycol monomethyl ether acetate was charged as a solvent, and stirring was started. Thereafter, the temperature of the solvent was raised to 80 ° C. In a dropping tank, 130 g of 2-methoxyethyl acrylate, 50 g of benzyl methacrylate, 20 g of acrylic acid and 0.5 g of 2,2′-azobisisobutyronitrile as a polymerization catalyst were added and stirred until the polymerization catalyst was dissolved. Was uniformly dropped into the flask for 3 hours, followed by polymerization at 80 ° C. for 5 hours. Then, it cooled to room temperature and obtained acrylic resin B4 of the mass mean molecular weight 92000 and glass transition point-10 degreeC.

<Example 1>
The following components (A) to (C) were dissolved in the following solvent. This was filtered with a membrane filter to prepare a positive resist composition.
(A) Component: Novolak resin A1 ... 100 parts by mass (B) Component: Acrylic resin B1 ... 17 parts by mass (C) Component: 1- [1- (4-hydroxyphenyl) isopropyl] -4- [ Photosensitizer in which 2 moles of hydrogen atoms of all phenolic hydroxyl groups of 1,1-bis (4-hydroxyphenyl) ethyl] benzene are replaced with 1,2-naphthoquinonediazide-4-sulfonyl group: 17 parts by mass solvent : Propylene glycol monoethyl ether acetate ... 190 parts by mass

<Example 2>
The following components (A) to (C) were dissolved in the following solvent. This was filtered with a membrane filter to prepare a positive resist composition.
(A) Component: Novolak resin A1 ... 100 parts by mass (B) Component: Acrylic resin B2 ... 17 parts by mass (C) Component: 1- [1- (4-hydroxyphenyl) isopropyl] -4- [ Photosensitizer in which 2 moles of hydrogen atoms of all phenolic hydroxyl groups of 1,1-bis (4-hydroxyphenyl) ethyl] benzene are replaced with 1,2-naphthoquinonediazide-4-sulfonyl group: 17 parts by mass solvent : Propylene glycol monoethyl ether acetate ... 190 parts by mass

<Example 3>
The following components (A) to (C) were dissolved in the following solvent. This was filtered with a membrane filter to prepare a positive resist composition.
(A) Component: Novolak resin A1 ... 100 parts by mass (B) Component: Acrylic resin B3 ... 17 parts by mass (C) Component: 1- [1- (4-hydroxyphenyl) isopropyl] -4- [ Photosensitizer in which 2 moles of hydrogen atoms of all phenolic hydroxyl groups of 1,1-bis (4-hydroxyphenyl) ethyl] benzene are replaced with 1,2-naphthoquinonediazide-4-sulfonyl group: 17 parts by mass solvent : Propylene glycol monoethyl ether acetate ... 190 parts by mass <Comparative Example 1>
The following (A) and (C) components were dissolved in the following solvent. This was filtered with a membrane filter to prepare a positive resist composition.
(A) Component: Novolak resin A1... 100 parts by mass (C) Component: 1- [1- (4-hydroxyphenyl) isopropyl] -4- [1,1-bis (4-hydroxyphenyl) ethyl] benzene Photosensitive agent in which 2 moles of hydrogen atoms of all phenolic hydroxyl groups in the above were substituted with 1,2-naphthoquinonediazide-4-sulfonyl group .... 17 parts by mass Solvent: propylene glycol monoethyl ether acetate ... 140 parts by mass

<Comparative example 2>
The following components (A) to (C) were dissolved in the following solvent. This was filtered with a membrane filter to prepare a positive resist composition.
(A) Component: Novolak resin A1 ... 100 parts by mass (B) Component: Acrylic resin B4 ... 17 parts by mass (C) Component: 1- [1- (4-hydroxyphenyl) isopropyl] -4- [ Photosensitizer in which 2 moles of hydrogen atoms of all phenolic hydroxyl groups of 1,1-bis (4-hydroxyphenyl) ethyl] benzene are replaced with 1,2-naphthoquinonediazide-4-sulfonyl group: 17 parts by mass solvent : Propylene glycol monoethyl ether acetate ... 190 parts by mass

<Evaluation>
Various physical properties of the positive resist compositions prepared in Examples 1 to 3 and Comparative Examples 1 and 2 were determined by the following methods. The results are shown in Table 1.

(1) Pattern shape evaluation A positive resist composition was applied onto a copper substrate using a spinner and dried on a hot plate at 110 ° C. for 240 seconds to obtain a resist film having a thickness of 10 μm. Next, a reduced projection exposure apparatus NSR-2005i10D (manufactured by Nikon Corporation, NA = 0.50) is used through this resist film through a predetermined mask, and a line / space with a mask dimension of 5 μm is finished according to the mask dimension. Exposed for 5-3 seconds. Next, as a developing operation, an aqueous 2.38 mass% tetramethylammonium hydroxide (TMAH) solution at 23 ° C. was applied onto the substrate, held for 60 seconds, and then shaken off by rotation of a spinner. This developing operation was repeated three times, then washed with water for 30 seconds and dried. The obtained pattern shape is observed with an SEM (scanning electron microscope), and the ratio (B / T) of the width (B) of the pattern bottom to the width (T) of the top of the space pattern is 0.90 ≦ ( B / T) ≦ 1.0 was evaluated as ○, 0.80 ≦ (B / T) <0.90 as Δ, and 0.8> (B / T) as ×.

(2) Evaluation of resolution A positive resist composition was applied onto a copper substrate using a spinner, and dried on a hot plate at 110 ° C. for 240 seconds to obtain a resist film having a thickness of 10 μm. Next, the resist film was exposed using a reduction projection exposure apparatus NSR-2005i10D (Nikon Corporation, NA = 0.50) through a predetermined mask. In the exposure amount where a line / space with a mask dimension of 5 μm is finished according to the mask dimension, the minimum mask dimension (μm) separated from the bottom of the pattern is set as the limit resolution, and the limit resolution is 3 μm or less, and larger than 3 μm Was evaluated as x.

(3) Evaluation of Resist Residue In the above “Evaluation of shape”, evaluation was made as “◯” when no resist residue was observed after development, and “X” when resist residue was observed.

(4) Evaluation of crack resistance (thermal shock resistance) A positive resist composition was applied on a copper substrate to a film thickness of 12 μm using a spinner and dried on a hot plate at 120 ° C. for 240 seconds. Immediately after that, it was cooled rapidly to 23 ° C. At this time, the case where cracks due to thermal shock were not recognized on the resist film surface was evaluated as ◯, the case where it was partially recognized as Δ, and the case where it was recognized as the entire substrate was evaluated as x.

  As can be seen from Table 1, the positive resist compositions of Examples 1 to 3 containing the alkali-soluble acrylic resin having the structural unit (b1) have good resist pattern shape and resolution, and development. Occasionally, no resist residue was generated and the crack resistance was good. On the other hand, the positive resist composition of Comparative Example 1 which does not contain an alkali-soluble acrylic resin has a good resist pattern shape and resolution, and no resist residue is generated during development, but has a crack resistance. It was extremely bad. In contrast, the positive resist composition of Comparative Example 2 containing an alkali-soluble acrylic resin having no (b1) structural unit was excellent in crack resistance, but the shape and resolution of the resist pattern. The resist residue was also generated during development.

Claims (8)

(A) an alkali-soluble novolak resin, (B) an alkali-soluble acrylic resin (excluding those having a fluorine atom) , and (C) a photosensitizer,
The (B) alkali-soluble acrylic resin has a structural unit (b1) represented by the following general formula (B-1), and has a mass average molecular weight of 50,000 to 200,000.
The positive resist composition, wherein the photosensitizer (C) is a quinonediazide group-containing compound.

[In General Formula (B-1), R ^1b represents a hydrogen atom or a methyl group, and R ^2b represents a linear or branched alkyl group having 5 or more carbon atoms which may have a substituent. . ] (A ′) an alkali-soluble novolak resin in which part of the hydrogen atoms of the total phenolic hydroxyl group is substituted with a 1,2-naphthoquinonediazidosulfonyl group, and (B) an alkali-soluble acrylic resin (however, those having a fluorine atom ) Excluding)
(B) the alkali-soluble acrylic resin have a represented by (b1) constituent units by the following formula (B-1), and a positive resist composition weight average molecular weight is characterized in that it is a 50000-200000 object.

[In General Formula (B-1), R ^1b represents a hydrogen atom or a methyl group, and R ^2b represents a linear or branched alkyl group having 5 or more carbon atoms which may have a substituent. . ]   The positive resist composition according to claim 2, further comprising (C) a photosensitizer. The positive resist composition according to any one of claims 1 to 3, wherein R ^{2b in the} general formula (B-1) is a branched alkyl group.   5. The positive resist composition according to claim 1, wherein the alkali-soluble acrylic resin (B) has a glass transition point (Tg) of −20 ° C. or lower.   The positive resist composition according to any one of claims 1 to 5, wherein a ratio of the (b1) constituent unit in the (B) alkali-soluble acrylic resin is 10 to 90% by mass.   The positive resist composition according to any one of claims 1 to 6, wherein the (B) alkali-soluble acrylic resin further comprises (b2) a structural unit derived from a polymerizable compound having a carboxyl group. . The positive resist composition according to any one of claims 1 to 7, wherein the acid value of the (B) alkali-soluble acrylic resin is 20 mgKOH / g or more.