TW202348648A - Copolymer, copolymer mixture, and positive resist composition - Google Patents

Abstract

The purpose of the present invention is to provide a copolymer capable of raising the pattern collapse resistance while maintaining the clarity of a resist pattern. The present invention is a copolymer having a monomer unit (I) represented by formula (I), a monomer unit (II) represented by formula (II) different from the monomer unit (I), and a monomer unit (III) represented by formula (III). Furthermore, in the formulas, L1, Ar1, X1, R1, X2, R2, R3, and R4 are predetermined groups, p and q are integers of 0-5 inclusive, and p + q = 5.

Description

Copolymers, copolymer mixtures and positive photoresist compositions

The present invention relates to copolymers, copolymer mixtures and positive photoresist compositions.

In the past, in fields such as semiconductor manufacturing, cutting was performed by irradiation with ionizing radiation such as electron beams or short-wavelength light such as ultraviolet light (hereinafter, ionizing radiation and short-wavelength light are sometimes collectively referred to as "ionizing radiation, etc."). Polymers that break the main chain to increase the solubility in the developer are used as main chain-cut positive photoresists.

Furthermore, for example, Patent Document 1 discloses a product composed of an α-chloroacrylic acid-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl ester unit and an α-methylstyrene unit. A positive photoresist made of a copolymer, which is a backbone-chain-cut positive photoresist that has excellent sensitivity to ionizing radiation, etc. and excellent heat resistance.

"Patent documents" "Patent Document 1": Japanese Patent Publication No. 2018-154754

Here, in the main chain cut type positive photoresist, it is required that the photoresist pattern obtained is clear, that is, the boundary between the portion of the photoresist film remaining (residual film) and the dissolved portion is clear. Specifically, from the perspective of making it possible to pattern a photoresist with higher definition, the photoresist is required to have the following characteristics: "If the irradiation dose does not reach a specific amount, it will not dissolve in the developer. The chain will be quickly cut off and dissolved in the developer, that is, the γ value that represents the slope of the sensitivity curve is increased. The sensitivity curve represents the common logarithm of the amount of exposure to ionizing radiation, etc., and the photoresist after development. relationship to the residual film thickness.

In addition, in the main chain cut type positive photoresist, the photoresist pattern may collapse (pattern collapse) when the photoresist pattern is formed by irradiation with ionizing radiation or the like and development using a developer. Therefore, in the main chain cut type positive photoresist, it is required to suppress this pattern collapse (in other words, to improve the pattern collapse resistance).

Therefore, an object of the present invention is to provide a copolymer that can improve the resistance to pattern collapse while ensuring the clarity of the photoresist pattern.

Furthermore, an object of the present invention is to provide a copolymer mixture that can improve the resistance to pattern collapse while ensuring the clarity of the photoresist pattern.

Furthermore, an object of the present invention is to provide a positive photoresist composition capable of forming a photoresist pattern with high resistance to pattern collapse while ensuring clarity.

The present inventors have devoted themselves to research in order to achieve the above object. Then, the inventor newly discovered that if a copolymer having three specified monomer units is used in a positive photoresist composition, the above problems can be solved, and the present invention was completed.

That is, this invention aims to successfully solve the above-mentioned problems. [1] The present invention is a copolymer having the following formula (I): 『Chemical 1』 [In the formula (I), L ¹ is a divalent linking group having a fluorine atom, Ar ¹ is an aromatic ring group which may have a substituent, and X ¹ is a halogen atom, a cyano group, an alkylsulfonyl group, or an alkoxy group. group, nitro group, acyl group, alkyl ester group or haloalkyl group. 〕The monomer unit (I) shown is different from the aforementioned monomer unit (I) by the following formula (II): 『Chemical 2』 [In the formula (II ⁾ , R ¹ is an organic group with the number of fluorine atoms being 3 or more and 10 or less, and Ester group or haloalkyl group. 〕The monomer unit (II) shown, and the following formula (III): 『Chemical 3』 [In formula (III), R ² is an alkyl group, R ³ is a hydrogen atom, a fluorine atom, an unsubstituted alkyl group or an alkyl group substituted with a fluorine atom, and R ⁴ is a hydrogen atom, an unsubstituted alkyl group or an alkyl group substituted with a fluorine atom. For atom-substituted alkyl groups, p and q are integers from 0 to 5, and p+q=5. 〕Monomer unit (III) shown.

If it is the above-mentioned copolymer, the clarity of the photoresist pattern can be ensured while the resistance to pattern collapse can be improved.

In addition, in this specification, "it may have a substituent" means "it is unsubstituted or it has a substituent".

[2] In the copolymer of [1] above, the number of fluorine atoms in R ¹ is preferably 5 or more.

If the number of fluorine atoms in R ¹ is above the above lower limit, the sensitivity of the copolymer to ionizing radiation, etc. can be improved.

[3] In the copolymer of [1] or [2] above, the number of fluorine atoms in L ¹ is preferably 4 or more.

If the number of fluorine atoms in L ¹ is more than the above lower limit, the sensitivity of the copolymer to ionizing radiation, etc. can be improved.

[4] In the copolymer of any one of the above [1] to [3], the total ratio of the aforementioned monomer unit (I) and the aforementioned monomer unit (II) is based on all the monomers in the aforementioned copolymer. When the unit is set to 100 mol%, it is preferably 45 mol% or more and 70 mol% or less.

If the total ratio of monomer units (I) and monomer units (II) is above the above lower limit when all monomer units in the copolymer are 100 mol%, the clarity of the photoresist pattern can be improved.

On the other hand, if the total ratio of monomer units (I) and monomer units (II) is below the above upper limit when all monomer units in the copolymer are 100 mol%, the pattern collapse resistance can be improved. sex. Furthermore, the amount of unintentional residue (hereinafter sometimes referred to as "photoresist residue") remaining below the line pitch portion of the photoresist pattern can be reduced.

In addition, in this specification, the proportion of monomer units in the copolymer can be measured using a nuclear magnetic resonance (NMR) method such as ¹ H-NMR.

Furthermore, this invention aims to successfully solve the above problems. [5] The present invention is a copolymer mixture including copolymer A and copolymer B, wherein the copolymer A is one of the above [1] to [4] In any of the copolymers, the difference between the surface free energy of the aforementioned copolymer B and the surface free energy of the aforementioned copolymer A is 3 mJ/m ² or more.

If it is the above-mentioned copolymer mixture, the clarity of the photoresist pattern can be ensured and the resistance to pattern collapse can be improved.

In addition, in this specification, "surface free energy" can be measured using the method described in the embodiments of this specification.

Furthermore, this invention aims to successfully solve the above problems. [6] The present invention is a copolymer mixture including copolymer A and copolymer B, wherein the copolymer A is one of the above [1] to [4] Any of the copolymers, the aforementioned copolymer B has the following formula (IV): 『Chemical 4』 [In the formula (IV), L ² is a divalent linking group having a fluorine atom, Ar ² is an aromatic ring group which may have a substituent, and X ³ is a halogen atom, a cyano group, an alkylsulfonyl group, or an alkoxy group. group, nitro group, acyl group, alkyl ester group or haloalkyl group. 〕The monomer unit (IV) shown is, and the following formula (V): 『Chemical 5』 [In the formula (V), R ⁵ is an alkyl group, R ⁶ is a hydrogen atom, an alkyl group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a carboxyl group or a halogenated carboxyl group, and R ⁷ is a hydrogen atom, an unsubstituted alkyl group or a fluorinated alkyl group. For atom-substituted alkyl groups, r and s are integers from 0 to 5, and r+s=5. 〕The monomer unit (V) shown.

If it is the above-mentioned copolymer mixture, the clarity of the photoresist pattern can be ensured and the resistance to pattern collapse can be improved.

Furthermore, this invention aims to successfully solve the above-mentioned problems. [7] The present invention is a positive photoresist composition containing any one of the following (A) to (C) and a solvent. (A) The copolymer of any one of the above [1] to [4] (B) A copolymer mixture including copolymer A and copolymer B, wherein the aforementioned copolymer A is the above [1] to [4] The copolymer of any one of the above, the difference between the surface free energy of the aforementioned copolymer B and the surface free energy of the aforementioned copolymer A is more than 3 mJ/m ² (C) A copolymer mixture, which includes copolymer A and copolymer B, wherein the aforementioned copolymer A is a copolymer of any one of the above [1] to [4], and the aforementioned copolymer B has the following formula (IV): 『Chemical 6』 [In the formula (IV), L ² is a divalent linking group having a fluorine atom, Ar ² is an aromatic ring group which may have a substituent, and X ³ is a halogen atom, a cyano group, an alkylsulfonyl group, or an alkoxy group. group, nitro group, acyl group, alkyl ester group or haloalkyl group. 〕The monomer unit (IV) shown is, and the following formula (V): 『Chemical 7』 [In the formula (V), R ⁵ is an alkyl group, R ⁶ is a hydrogen atom, an alkyl group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a carboxyl group or a halogenated carboxyl group, and R ⁷ is a hydrogen atom, an unsubstituted alkyl group or a fluorinated alkyl group. For atom-substituted alkyl groups, r and s are integers from 0 to 5, and r+s=5. 〕Single unit (V) shown

If the positive photoresist composition is used, it is possible to form a photoresist pattern that is highly resistant to pattern collapse while ensuring clarity.

[8] In the positive photoresist composition of the above [7], it is preferable that there is substantially no component with a weight average molecular weight of less than 1,000.

If there is substantially no component with a weight average molecular weight of less than 1,000, the clarity of the photoresist pattern can be improved.

In addition, in this specification, the proportion (presence or absence) of "components with a weight average molecular weight less than 1,000" can be measured using the method described in the Examples.

In addition, in this specification, the term "substantially does not contain" means that it is not actively blended and excludes unavoidable mixing. Specifically, it means that the content ratio of components with a weight average molecular weight of less than 1000 in the positive photoresist composition does not reach 0.05% by mass.

According to the present invention, a copolymer capable of improving pattern collapse resistance while ensuring the clarity of a photoresist pattern can be provided.

Furthermore, according to the present invention, it is possible to provide a copolymer mixture that can improve the pattern collapse resistance while ensuring the clarity of the photoresist pattern.

Furthermore, according to the present invention, it is possible to provide a positive photoresist composition capable of forming a photoresist pattern with high resistance to pattern collapse while ensuring clarity.

The embodiments of the present invention will be described in detail below.

Here, the copolymer of the present invention can be suitably used in a main chain-cut positive photoresist composition in which the main chain is cut by ionizing radiation or the like to reduce the molecular weight. In addition, the copolymer mixture of the present invention containing the copolymer of the present invention can also be well used in a main chain scission-type positive photoresist composition. Furthermore, the positive photoresist composition of the present invention, which contains the copolymer of the present invention or the copolymer mixture of the present invention, can be used to form photoresist patterns in the process of printing substrates such as build-up substrates.

(copolymer)

The copolymer of the present invention has the following formula (I): 『Chemical 8』 [In the formula (I), L ¹ is a divalent linking group having a fluorine atom, Ar ¹ is an aromatic ring group which may have a substituent, and X ¹ is a halogen atom, a cyano group, an alkylsulfonyl group, or an alkoxy group. group, nitro group, acyl group, alkyl ester group or haloalkyl group. 〕The monomer unit (I) shown is different from the monomer unit (I) by the following formula (II): 『Chemical 9』 [In the formula (II ⁾ , R ¹ is an organic group with the number of fluorine atoms being 3 or more and 10 or less, and Ester group or haloalkyl group. 〕The monomer unit (II) shown is, and the following formula (III): 『Chemical 10』 [In formula (III), R ² is an alkyl group, R ³ is a hydrogen atom, a fluorine atom, an unsubstituted alkyl group or an alkyl group substituted with a fluorine atom, and R ⁴ is a hydrogen atom, an unsubstituted alkyl group or an alkyl group substituted with a fluorine atom. For atom-substituted alkyl groups, p and q are integers from 0 to 5, and p+q=5. 〕Monomer unit (III) shown.

In addition, the copolymer of the present invention may also contain any monomer unit other than the monomer unit (I), the monomer unit (II) and the monomer unit (III), but among all the monomer units constituting the copolymer, the monomer unit The proportion of unit (I), monomer unit (II) and monomer unit (III) is preferably 90 mol% or more in total, and 100 mol% (that is, the copolymer only contains monomer unit (I) , monomer unit (II) and monomer unit (III)) are preferred.

Here, as long as the copolymer of the present invention has monomer units (I), monomer units (II) and monomer units (III), it may also be, for example, a random copolymer, a block copolymer, a ternary alternating copolymer, etc. Any one, but ternary alternating copolymer is preferred. In addition, in this specification, the so-called ternary alternating copolymer refers to an alternating copolymer in which the monomer unit (I) or the monomer unit (II) is copolymerized between the monomer units (III). That is, to express schematically, each monomer unit is bonded in the form of "-(III)-(I)-(III)-(II)-(III)-".

The copolymer of the present invention has designated monomer units (I), monomer units (II) and monomer units (III). If the irradiation amount of ionizing radiation or the like reaches a specific amount, only the irradiated part of the copolymer The main chain will be well cut and the molecular weight will be reduced. Moreover, the low-molecular components are well dissolved in the developer. Thereby, the clarity of the photoresist pattern can be ensured (that is, the γ value becomes higher.). The reason for this is not clear, but it is presumed that the sensitivity to ionizing radiation, etc. and the ease of generation of free radicals when irradiated with ionizing radiation etc. vary depending on the difference between L ¹ of the monomer unit (I) and the monomer unit (II). This is because the ability of the fluorine atom in R ¹ to pull electrons increases.

Furthermore, the copolymer of the present invention can improve pattern collapse resistance by having designated monomer units (I), monomer units (II) and monomer units (III). The reason for this is not clear, but it is presumed that the liquid repellency of the copolymer is increased by the fluorine atoms in L ¹ of the monomer unit (I) and R ¹ of the monomer unit (II), which can be used in the photoresist. This prevents the patterns from pulling together when removing the developer or rinse solution during the pattern formation process.

Furthermore, the copolymer of the present invention can suppress the generation of photoresist residue by having designated monomer units (I), monomer units (II) and monomer units (III). The reason for this is not clear, but it is presumed that the solubility in the developer increases due to the aromatic ring group contained in the monomer unit (I) and the monomer unit (III).

〈Monomer unit (I)〉

Here, the monomer unit (I) is derived from the following formula (a): 『Chemical 11』 [In formula (a), L ¹ , Ar ¹ and X ¹ are the same as in formula (I). 〕The structural unit of the monomer (a) shown.

Examples of the divalent connecting group having a fluorine atom that constitutes L ¹ in the formula (I) and the formula (a) include a divalent chain alkyl group having 1 to 5 carbon atoms having a fluorine atom. Specifically, examples of the divalent linking group having a fluorine atom include trifluoromethylmethylene, pentafluoroethylmethylene, bis(trifluoromethyl)methylene, and the like. Among these, pentafluoroethylmethylene and bis(trifluoromethyl)methylene are preferred, and bis(trifluoromethyl)methylene is more preferred.

The number of fluorine atoms in L ¹ (divalent linking group having a fluorine atom) is preferably 3 or more, more preferably 4 or more, more preferably 5 or more, preferably 10 or less, and more preferably 7 or less. good.

If the number of fluorine atoms in L ¹ is above the above lower limit, the sensitivity to ionizing radiation and the like and the clarity of the photoresist pattern can be improved.

On the other hand, if the number of fluorine atoms in L ¹ is less than the above upper limit, the production efficiency of the copolymer can be improved.

Examples of the optionally substituted aromatic ring group constituting Ar ¹ in formula (I) and formula (a) include: an optionally substituted aromatic hydrocarbon ring group and an optionally substituted aromatic heterocyclic group. .

The aromatic hydrocarbon ring group is not particularly limited, and examples thereof include phenyl ring group, biphenyl ring group, naphthyl ring group, azulenyl ring group, anthracenyl ring group, phenanthrene ring group, pyrene ring group, phenyl ring group, pyrene ring group, and pyrene ring group. Benzene ring group, di-triphenyl ring group, o-triphenyl ring group, meta-triphenyl ring group, p-triphenyl ring group, ethane naphthalenyl ring group, benzene ring group, fluorine ring group, allene fluoride group Ring base, fused pentaphenyl ring base, perylene ring base, iso-fused pentaphenyl ring base, sulfenyl ring base, ranyl ring base, etc.

The aromatic heterocyclic ring is not particularly limited, and examples thereof include furan ring group, thiophene ring group, pyridine ring group, pyridine ring group, pyrimidine ring group, pyridine ring group, trioxadiazole ring group, and oxadiazole ring. base, triazole ring base, imidazole ring base, pyrazole ring base, thiazole ring base, indole ring base, benzimidazole ring base, benzothiazole ring base, benzothiazole ring base, quinoline ring base, Quinazoline ring group, fluorine ring group, benzofuran ring group, dibenzofuran ring group, benzothiophene ring group, dibenzothiophene ring group, carbazole ring group, etc.

The substituent Ar ¹ has is not particularly limited, and examples include an alkyl group, a fluorine atom, a fluoroalkyl group, and the like. Examples of "the alkyl group having a substituent as Ar ¹ " include chain alkyl groups having 1 to 6 carbon atoms such as methyl, ethyl, propyl, n-butyl, isobutyl, and the like. Examples of "the fluoroalkyl group having a substituent as Ar ¹ " include fluoroalkyl groups having 1 to 5 carbon atoms such as trifluoromethyl, trifluoroethyl, and pentafluoropropyl.

Among them, from the viewpoint of improving the ease of production of the copolymer, Ar ¹ is preferably an aromatic hydrocarbon ring group which may have a substituent, an unsubstituted aromatic hydrocarbon ring group is more preferred, and a phenyl ring group (phenyl group) is preferred. ) is better.

Examples of the halogen atom constituting X ¹ in formula (I) and formula (a) include a chlorine atom, a fluorine atom, a bromine atom, an iodine atom, and an acetate atom.

Examples of the alkylsulfonyl group constituting X ¹ in formula (I) and formula (a) include methanesulfonyl group, ethylsulfonyl group, and the like.

Examples of the alkoxy group constituting X ¹ in formula (I) and formula (a) include methoxy group, ethoxy group, propoxy group, and the like.

Examples of the acyl group constituting X ¹ in the formula (I) and formula (a) include a formyl group, an acetyl group, a propyl group, and the like.

Examples of the alkyl ester group constituting X ¹ in formula (I) and formula (a) include methyl ester group, ethyl ester group, and the like.

Examples of the halogenated alkyl group constituting X ¹ in formula (I) and formula (a) include halogenated methyl groups with the number of halogen atoms being 1 or more and 3 or less.

Among the above, X ¹ is preferably a halogen atom, and more preferably a chlorine atom.

From the viewpoint of fully improving the sensitivity to ionizing radiation and the like, the monomer (a) represented by the formula (a) is selected from the group consisting of α-chloroacrylic acid-1-phenyl-1-trifluoromethyl-2 ,2,2-trifluoroethyl ester (ACAFPh), α-chloroacrylic acid-1-phenyl-2,2,2-trifluoroethyl ester (ACAHFPh) and α-chloroacrylic acid-1-(4-methoxy At least one monomer from the group consisting of phenyl)-1-trifluoromethyl-2,2,2-trifluoroethyl ester (ACAFPhOMe) is preferred, with α-chloroacrylic acid-1-phenyl-1 -Trifluoromethyl-2,2,2-trifluoroethyl ester is preferred. That is, the copolymer has a unit selected from the group consisting of α-chloroacrylic acid-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl ester, α-chloroacrylic acid-1-phenyl-2, A group of 2,2-trifluoroethyl ester units and α-chloroacrylic acid-1-(4-methoxyphenyl)-1-trifluoromethyl-2,2,2-trifluoroethyl ester units It is preferable to have at least one kind of monomer unit, and it is preferable to have an α-chloroacrylic acid-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl ester unit.

The proportion of monomer units (I) in the copolymer is preferably 1 mol% or more, preferably 3 mol% or more, and 5 mol% when all monomer units in the copolymer are 100 mol%. More preferably, 8 mol% or more is more preferred, 40 mol% or less is more preferred, 30 mol% or less is more preferred, 20 mol% or less is more preferred, and 15 mol% or less is more preferred. For better.

If the proportion of monomer units (I) in the copolymer is above the above lower limit when all monomer units in the copolymer are 100 mol%, the pattern collapse resistance of the photoresist pattern can be improved. Moreover, the amount of photoresist residue can be reduced.

On the other hand, if the proportion of monomer units (I) in the copolymer is below the above upper limit when all monomer units in the copolymer are 100 mol%, the sensitivity and sensitivity to ionizing radiation, etc. can be improved. Clarity of photoresist pattern.

〈Monomer unit (II)〉

Here, the monomer unit (II) that is different from the monomer unit (I) is derived from the following formula (b) that is different from the monomer unit (a): 『Chemical 12』 [In formula (b), R ¹ and X ² are the same as in formula (II). 〕The structural unit of the monomer (b) shown.

R ¹ in formula (II) and formula (b) is an organic group with the number of fluorine atoms being 3 or more and 10 or less. Furthermore, the number of fluorine atoms in R ¹ is preferably 5 or more, more preferably 6 or more, more preferably 7 or more, more preferably 8 or more, and more preferably 9 or less.

If the number of fluorine atoms in R ¹ is above the above lower limit, the sensitivity to ionizing radiation and the like and the clarity of the photoresist pattern can be improved. Furthermore, if the number of fluorine atoms in R ¹ is 8 or more, the production efficiency of the copolymer can be improved.

On the other hand, if the number of fluorine atoms in R ¹ is less than the above upper limit, the production efficiency of the copolymer can also be improved. Furthermore, although the reason is not yet determined, if the number of fluorine atoms in R ¹ is less than the above upper limit, the sensitivity to ionizing radiation and the like can be improved.

The carbon number of R ¹ in formula (II) and formula (b) is preferably 2 or more and 10 or less, and more preferably 5 or less.

If the number of carbon atoms is equal to or higher than the above-mentioned lower limit, the solubility in the developer can be sufficiently improved.

On the other hand, if the carbon number is below the above upper limit, the clarity of the photoresist pattern can be fully guaranteed.

The organic group in R ¹ is preferably in the form of a chain without an aromatic ring. Examples of such organic groups include: fluoroalkyl groups such as the following (b-1) to (b-31); fluoroalkoxyalkyl groups such as the following (b-32) to (b-55); fluoroethoxyethylene Such as fluoroalkoxyalkenyl; etc.

"Chemical 13"

"Chemical 14"

Among the above, the organic group in R ¹ is preferably a fluoroalkyl group. The fluoroalkyl group of (b-13) (2,2,2-trifluoroethyl), the fluoroalkyl group of (b-20) ( 2,2,3,3,3-pentafluoropropyl), (b-25) fluoroalkyl (2,2,3,3,4,4,4-heptafluorobutyl) or (b-31 ) of the fluoroalkyl group (2,2,3,3,4,4,5,5,5-nonafluoropentyl) is preferred, with 2,2,3,3,3-pentafluoropropyl, 2 ,2,3,3,4,4,4-heptafluorobutyl or 2,2,3,3,4,4,5,5,5-nonafluoropentyl is more preferred, with 2,2,3 ,3,4,4,4-heptafluorobutyl or 2,2,3,3,4,4,5,5,5-nonafluoropentyl is more preferred, with 2,2,3,3, 4,4,5,5,5-nonafluoropentyl is further preferred.

Examples of the halogen atom constituting X ² in the formula (II) and the formula (b) include a chlorine atom, a fluorine atom, a bromine atom, an iodine atom, and a styrene atom.

Examples of the alkylsulfonyl group constituting X ² in formula (II) and formula (b) include a methanesulfonyl group, an ethylsulfonyl group, and the like.

Examples of the alkoxy group constituting X ² in formula (II) and formula (b) include methoxy group, ethoxy group, propoxy group, and the like.

Examples of the acyl group constituting X ² in formula (II) and formula (b) include formyl group, acetyl group, propyl group, and the like.

Examples of the alkyl ester group constituting X ² in formula (II) and formula (b) include methyl ester group, ethyl ester group, and the like.

Examples of the halogenated alkyl group constituting X ² in formula (II) and formula (b) include halogenated methyl groups with the number of halogen atoms being from 1 to 3.

Among the above, X ² is preferably a halogen atom, more preferably a chlorine atom, and more preferably the same as X ¹ .

More specifically, examples of the monomer (b) represented by the formula (b) include α-chloroacrylic acid-2,2,2-trifluoroethyl ester (ACATFE), α-chloroacrylic acid-2, 2,3,3,3-pentafluoropropyl ester (ACAPFP), α-chloroacrylic acid-3,3,4,4,4-pentafluorobutyl ester, α-chloroacrylic acid-2,2,3,3,4 ,4,5,5,5-nonafluoropentyl ester, α-chloroacrylate-1H-1-(trifluoromethyl)trifluoroethyl ester, α-chloroacrylate-1H,1H,3H-hexafluorobutyl ester, α-Chloroacrylate-1,2,2,2-tetrafluoro-1-(trifluoromethyl)ethyl ester, α-chloroacrylate-2,2,3,3,4,4,4-heptafluorobutyl ester (ACAHFB) and other α-chloroalkyl acrylates; α-chloropentafluoroethoxymethyl acrylate, α-chloropentafluoroethoxyethyl acrylate and other α-chloroalkyl acrylates; α-chloropentafluoroacrylate Ethoxyethylene ester and other α-chloroalkoxyalkyl acrylate; etc.

Among these, α-fluoroalkyl acrylate is preferred in terms of improving the sensitivity to ionizing radiation, and α-chloroacrylate-2,2,2-trifluoroethyl, α-chloroacrylate- 2,2,3,3,3-pentafluoropropyl ester, α-chloroacrylic acid-2,2,3,3,4,4,4-heptafluorobutyl ester, α-chloroacrylic acid-2,2,3, 3,4,4,5,5,5-nonafluoropentyl is preferred, with α-chloroacrylic acid-2,2,3,3,3-pentafluoropropyl ester, α-chloroacrylic acid-2,2, 3,3,4,4,4-heptafluorobutyl ester is more preferred, α-chloroacrylic acid-2,2,3,3,4,4,4-heptafluorobutyl ester and α-chloroacrylic acid-2, 2,3,3,4,4,5,5,5-nonafluoropentyl is more preferred, and α-chloroacrylic acid 2,2,3,3,4,4,5,5,5-nonafluoro Amyl ester is further preferred. That is, the copolymer preferably has α-chloroacrylic acid fluoroalkyl ester units, and preferably has α-chloroacrylic acid-2,2,2-trifluoroethyl units, α-chloroacrylic acid-2,2,3, 3,3-pentafluoropropyl ester unit, α-chloroacrylic acid-2,2,3,3,4,4,4-heptafluorobutyl ester unit and α-chloroacrylic acid-2,2,3,3,4, It is preferred that at least one monomer unit of the group consisting of 4,5,5,5-nonafluoropentyl units has a monomer unit selected from α-chloroacrylic acid-2,2,3,3,3-pentafluoro Propyl ester unit, α-chloroacrylic acid-2,2,3,3,4,4,4-heptafluorobutyl unit and α-chloroacrylic acid-2,2,3,3,4,4,5,5, It is more preferred that at least one monomer unit of the group consisting of 5-nonafluoropentyl ester unit has α-chloroacrylic acid-2,2,3,3,4,4,4-heptafluorobutyl unit and It is more preferred that at least any monomer unit of the α-chloroacrylic acid-2,2,3,3,4,4,5,5,5-nonafluoropentyl unit has α-chloroacrylic acid-2,2 ,3,3,4,4,5,5,5-nonafluoropentyl unit is further preferred.

The proportion of monomer units (II) in the copolymer is preferably 10 mol% or more, preferably 20 mol% or more, and 30 mol% when all monomer units in the copolymer are 100 mol%. Mol% or more is more preferred, 35 mol% or more is more preferred, 70 mol% or less is preferred, 60 mol% or less is preferred, 50 mol% or less is more preferred, and 45 mol% or less is more preferred. For better.

If the proportion of monomer units (II) in the copolymer is above the above lower limit when all monomer units in the copolymer are 100 mol%, the sensitivity to ionizing radiation and the like and the quality of the photoresist pattern can be improved. Clarity.

On the other hand, if the proportion of monomer units (II) in the copolymer is below the above upper limit when all monomer units in the copolymer are 100 mol%, the pattern collapse resistance of the photoresist pattern can be improved. sex. Moreover, the amount of photoresist residue can be reduced.

In addition, the total ratio of monomer units (I) and monomer units (II) in the copolymer is preferably 45 mol% or more, assuming that all monomer units in the copolymer are 100 mol%. 47 mol% or more is preferred, 70 mol% or less is preferred, 60 mol% or less is preferred, and 55 mol% or less is more preferred.

If the total ratio of monomer units (I) and monomer units (II) in the copolymer is above the above lower limit when all monomer units in the copolymer are 100 mol%, the photoresist pattern can be improved of clarity.

On the other hand, if the total ratio of monomer units (I) and monomer units (II) in the copolymer is less than the above upper limit when all monomer units in the copolymer are taken as 100 mol%, then it can be Improves resistance to pattern collapse. Moreover, the amount of photoresist residue can be reduced.

〈Monomer unit (III)〉

Here, the monomer unit (III) is derived from the following formula (c): 『Chemical 15』 [In formula (c), R ² to R ⁴ , p and q are the same as in formula (III). 〕The structural unit of the monomer (c) shown.

The alkyl group constituting R ² in formula (III) and formula (c) is not particularly limited, and examples thereof include alkyl groups having 1 to 5 carbon atoms. Among them, the alkyl group constituting R ² is preferably a methyl group or an ethyl group.

The unsubstituted alkyl group constituting R ³ and R ⁴ in formula (III) and formula (c) is not particularly limited, and examples thereof include unsubstituted alkyl groups having 1 to 5 carbon atoms. Among them, the unsubstituted alkyl group constituting R ³ and R ⁴ is preferably a methyl group or an ethyl group.

The alkyl group substituted with a fluorine atom to form R ³ and R ⁴ in formula (III) and formula (c) is not particularly limited. Examples include alkyl groups having one or all of the hydrogen atoms in the alkyl group. The basis of the structure substituted by fluorine atoms.

In formula (III) and formula (c), when p is 2 or more, each R ³ may be the same as each other or different. Moreover, when q is 2 or more, each R ⁴ may be the same as each other or may be different.

In addition, for formula (III) and formula (c), p=5 (that is, q=0) is preferred.

From the perspective of improving the ease of preparation of the copolymer, it is preferred that there are multiple R ³ and/or R ⁴ in formula (III) and formula (c), all of which are hydrogen atoms or unsubstituted alkyl groups. The alkyl group having all hydrogen atoms or an unsubstituted alkyl group having 1 to 5 carbon atoms is preferred, and the alkyl group having all hydrogen atoms is more preferred.

The monomer (c) represented by the formula (c) is not particularly limited, and examples thereof include α-methylstyrene (AMS) such as the following monomers (c-1) to (c-11) and Its derivatives (e.g. 4-fluoro-α-methylstyrene: 4FAMS).

"Chemical 16"

In addition, from the viewpoint of improving the ease of preparation of the copolymer and the cleavage property of the main chain when irradiating an electron beam or the like, α-methylbenzene is used as the monomer (c) represented by the formula (c). Ethylene (c-1) or 4-fluoro-α-methylstyrene (c-2) is preferred, and α-methylstyrene is preferred. That is, the copolymer preferably has α-methylstyrene units or 4-fluoro-α-methylstyrene units, and the copolymer preferably has α-methylstyrene units.

The proportion of monomer units (III) in the copolymer is not particularly limited. When all monomer units in the copolymer are set to 100 mol%, it can be, for example, 30 mol% or more, and 40 mol%. The above is preferred, and 45 mol% or more is more preferred, and it can be, for example, 70 mol% or less, 60 mol% or less is preferred, 55 mol% or less is preferred, and 53 mol% or less is more preferred.

〈Characteristics of copolymer〉

[Weight average molecular weight (Mw)]

The weight average molecular weight (Mw) of the copolymer is preferably 10,000 or more, more preferably 17,000 or more, more preferably 25,000 or more, and preferably 250,000 or less, 180,000 or less is more preferably, 80,000 or less is more preferably, Less than 50,000 is better.

If the weight average molecular weight (Mw) of the copolymer is equal to or higher than the above-mentioned lower limit, the solubility of the photoresist film to the developer under low irradiation dose can be suppressed from being too high.

On the other hand, if the weight average molecular weight (Mw) of the copolymer is below the above upper limit, the positive photoresist composition can be easily prepared.

In addition, in this specification, "weight average molecular weight" can be measured using the method described in the Examples.

[Number average molecular weight (Mn)]

The number average molecular weight (Mn) of the copolymer is preferably 7,000 or more, preferably 10,000 or more, more preferably 20,000 or more, and 150,000 or less, preferably 100,000 or less, and 70,000 or less. Less than 40,000 is better.

If the number average molecular weight (Mn) of the copolymer is equal to or higher than the above lower limit, excessive solubility of the photoresist film in the developer under low irradiation dose can be further suppressed, and a photoresist pattern with further improved definition can be formed.

On the other hand, if the number average molecular weight (Mn) of the copolymer is below the above upper limit, the positive photoresist composition can be prepared more easily.

In addition, in this specification, "number average molecular weight" can be measured in the form of a standard polystyrene converted value using gel permeation chromatography.

[Molecular weight distribution (Mw/Mn)]

The molecular weight distribution (Mw/Mn) of the copolymer is preferably 1.10 or more, more preferably 1.20 or more, more preferably 1.45 or more, and 1.80 or less, preferably 1.70 or less, and 1.65 or less. .

If the molecular weight distribution (Mw/Mn) of the copolymer is not less than the above lower limit, the ease of production of the copolymer can be improved.

On the other hand, if the molecular weight distribution (Mw/Mn) of the copolymer is below the above upper limit, the clarity of the obtained photoresist pattern can be further improved.

In addition, in this specification, "molecular weight distribution" can be obtained by calculating the ratio of the weight average molecular weight to the number average molecular weight (weight average molecular weight/number average molecular weight).

[Surface free energy]

The surface free energy of the copolymer is preferably above 18 mJ/m ² , preferably above 19 mJ/m ² , preferably above 20 mJ/m ² , and preferably below 27 mJ/m ² , with 26 mJ/m ² or less is preferred, 25 mJ/m ² or less is more preferred, 24 mJ/m ² or less is more preferred, and 22 mJ/m ² or less is further preferred.

In addition, the surface free energy can be adjusted by the type or proportion of monomer units constituting the copolymer.

〈Preparation method of copolymer〉

The preparation method of the copolymer is not particularly limited. For example, a copolymer having monomer units (I), monomer units (II) and monomer units (III) can be prepared by containing monomer (a), monomer (b), monomer ( c) After polymerization with a monomer composition of any monomer that can be copolymerized with these monomers, the obtained copolymer is recovered and optionally purified to prepare.

In addition, the composition, molecular weight distribution, number average molecular weight and weight average molecular weight of the copolymer can be adjusted by changing the polymerization conditions and purification conditions. For example, if the polymerization temperature is lowered, the number average molecular weight and the weight average molecular weight can be increased. Furthermore, if the polymerization time is shortened, the number average molecular weight and weight average molecular weight can be increased. Furthermore, if purified, the molecular weight distribution can be reduced.

[Polymerization of monomer components]

As the monomer composition used in the preparation of the copolymer, for example, "a monomer including monomer (a), monomer (b), monomer (c) and any monomer capable of copolymerizing with these monomers can be used. It is a mixture of bulk components, optional solvents, optional polymerization initiators, and optional additives. Furthermore, the polymerization of the monomer composition can be carried out using known methods. Among them, as the solvent, cyclopentanone, water, etc. are preferably used. Furthermore, as the polymerization initiator, it is preferable to use, for example, azobisisobutyronitrile or the like.

The polymerization crude product obtained by polymerizing the monomer composition is not particularly limited. After adding a good solvent such as tetrahydrofuran to a solution containing the polymerization crude product, the solution containing the good solvent is added dropwise to methanol, ethanol, or The crude polymerization product is condensed and recovered in poor solvents such as 1-propanol, 1-butanol, 1-pentanol, and hexane.

[Purification of crude polymerization product]

The purification method used when purifying the obtained crude polymerization product is not particularly limited, and may include known purification methods such as reprecipitation or column chromatography. Among them, the reprecipitation method is preferably used as the purification method.

In addition, the purification of the crude polymerization product can also be repeated multiple times.

Purification of the crude polymerization product by the reprecipitation method is preferably carried out, for example, as follows: after dissolving the obtained crude polymerization product in a good solvent such as tetrahydrofuran, the obtained solution is added dropwise To a mixed solvent of good solvents such as tetrahydrofuran and poor solvents such as methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, hexane, etc., a part of the crude polymerization product can be separated out. If the solution of the crude polymerization product is dropped into a mixed solvent of a good solvent and a poor solvent for purification, the molecular weight distribution of the obtained copolymer can be easily adjusted by changing the type or mixing ratio of the good solvent and the poor solvent. , number average molecular weight and weight average molecular weight. For example, the higher the proportion of good solvent in the mixed solvent, the greater the molecular weight of the copolymer precipitated in the mixed solvent can be increased.

When the crude polymerization product is purified by the reprecipitation method, as long as the copolymer satisfies the desired properties, the crude polymerization product precipitated in a mixed solvent of a good solvent and a poor solvent can be used, or a copolymer that has not been mixed can be used. The crude polymerization product precipitated from the solvent (that is, the crude polymerization product dissolved in the mixed solvent). Here, the crude polymerization product that has not precipitated in the mixed solvent can be recovered from the mixed solvent using known methods such as concentration to dryness.

(copolymer blend)

The copolymer mixture of the present invention includes copolymer A and copolymer B, optionally further including polymers other than copolymer A and copolymer B. Furthermore, in the copolymer mixture of the present invention, copolymer A is the copolymer of the present invention. Since the copolymer of the present invention can ensure the clarity of the photoresist pattern while improving the resistance to pattern collapse, the copolymer mixture of the present invention including this copolymer can also ensure the clarity of the photoresist pattern while improving the resistance to pattern collapse. Collapse. In addition, there are usually no solvents in the copolymer mixture.

〈Copolymer A〉

As copolymer A, the copolymer of the present invention is used. Since the details of the copolymer of the present invention have been described above, the description is omitted here.

[Proportion of copolymer A]

The content ratio of the copolymer A in the copolymer mixture is preferably 1 mass % or more, more preferably 5 mass % or more, and 10 mass % when the total of all components of the copolymer mixture is 100 mass %. % or more is more preferred, 15 mass % or more is more preferred, 40 mass % or less is more preferred, 30 mass % or less is more preferred, and 25 mass % or less is more preferred.

If the proportion of copolymer A in the copolymer mixture is equal to or higher than the above-mentioned lower limit when the sum of all components of the copolymer mixture is 100% by mass, the clarity of the photoresist pattern can be improved.

On the other hand, if the proportion of copolymer A in the copolymer mixture is equal to or less than the above upper limit when the total of all components of the copolymer mixture is 100% by mass, the sensitivity to ionizing radiation and the like can be improved.

〈Copolymer B〉

The copolymer B is not particularly limited as long as it is a polymer that does not conform to the copolymer of the present invention and the main chain is cut by irradiation with ultraviolet rays or the like, and any copolymer can be used. Examples of copolymers in which the main chain is cut include the copolymers described in Japanese Patent Publication No. 2022-65445.

Among them, as the copolymer B, (1) a copolymer with a surface free energy difference of 3 mJ/m ² or more from the copolymer A or (2) a copolymer having the monomer unit (IV) and the monomer described later can be used. Copolymers of unit (V) are preferred.

In addition, as the copolymer B, it is preferable to use a copolymer that has a surface free energy difference from the copolymer A of 3 mJ/m ² or more and has a monomer unit (IV) and a monomer unit (V).

Here, in the embodiment of (1) above, the difference between the surface free energy of copolymer B and the surface free energy of copolymer A is 3 mJ/m ² or more. If the difference between the surface free energy of copolymer B and the surface free energy of copolymer A is 3 mJ/m ² or more, the clarity of the photoresist pattern can be ensured while the pattern collapse resistance can be improved.

The difference between the surface free energy of copolymer B and the surface free energy of copolymer A is preferably 4 mJ/m ² or more, 5.5 mJ/m ² or more is better, 6 mJ/m ² or more is better, and 6.5 mJ/m ² or more is more preferred, 8 mJ/m ² or more is still more preferred, 9 mJ/m ² or more is still more preferred, and 10 mJ/m ² or more is particularly preferred.

If the difference between the surface free energy of copolymer B and the surface free energy of copolymer A is above the above lower limit, the clarity of the photoresist pattern can be improved.

On the other hand, the difference between the surface free energy of copolymer B and the surface free energy of copolymer A is, for example, 14 mJ/m ² or less, or it may be 13 mJ/m ² or less, or it may be 12 mJ/m ² or less. It can also be 11 mJ/m ² or less.

Here, the surface free energy of copolymer B can be larger or smaller than the surface free energy of copolymer A, but the relationship between the surface free energy of copolymer B and the surface free energy of copolymer A can be easily adjusted. In other words, the surface free energy of copolymer B is preferably greater than the surface free energy of copolymer A (that is, "surface free energy of copolymer B" > "surface free energy of copolymer A").

In addition, the surface free energy of copolymer B is preferably 28 mJ/m ² or more, more preferably 29 mJ/m ² or more, more preferably 30 mJ/m ² or more, and 35 mJ/m ² or less. The best is 34 mJ/m ² or less, and 33 mJ/m ² or less is even better.

Here, in the embodiment of (2) above, copolymer B has the following formula (IV): 『Chemical 17』 [In the formula (IV), L ² is a divalent linking group having a fluorine atom, Ar ² is an aromatic ring group which may have a substituent, and X ³ is a halogen atom, a cyano group, an alkylsulfonyl group, or an alkoxy group. group, nitro group, acyl group, alkyl ester group or haloalkyl group. 〕The monomer unit (IV) shown is, and the following formula (V): 『Chemical 18』 [In the formula (V), R ⁵ is an alkyl group, R ⁶ is a hydrogen atom, an alkyl group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a carboxyl group or a halogenated carboxyl group, and R ⁷ is a hydrogen atom, an unsubstituted alkyl group or a fluorinated alkyl group. For atom-substituted alkyl groups, r and s are integers from 0 to 5, and r+s=5. 〕The monomer unit (V) shown. If copolymer B has monomer units (IV) and monomer units (V), it can ensure the clarity of the photoresist pattern while improving the pattern collapse resistance.

In addition, copolymer B may also contain any monomer unit other than monomer unit (IV) and monomer unit (V) (but excluding monomer unit (II).), but in all monomer units constituting copolymer B The proportion of the monomer unit (IV) and the monomer unit (V) is preferably more than 90 mol% in total, and 100 mol% (that is, the copolymer B only contains the monomer unit (IV) and the monomer Unit (V)) is preferred.

Here, the copolymer B may be any of a random copolymer, a block copolymer, an alternating ternary copolymer, etc., but a ternary alternating copolymer is preferred.

[Monomeric unit (IV)]

Here, the monomer unit (IV) is derived from the following formula (d): 『Chemical 19』 [In formula (d), L ² , Ar ² and X ³ are the same as in formula (IV). 〕The structural unit of the monomer (d) shown.

Examples of the divalent linking group having a fluorine atom that constitutes L ² in the formula (IV) and the formula (d) include a fluorine atom that constitutes L ¹ in the formula (I) and the formula (a). The linking base of 2 valences is the same base.

Examples of the aromatic ring group that may have a substituent for Ar ² constituting the formula (IV) and the formula (d) include those that may have a substituent for Ar ¹ constituting the formula (I) and the formula (a). The aromatic ring group of the base is the same.

Examples of the halogen atom constituting X ³ in formula (IV) and formula (d) include the same groups as the halogen atom constituting X ¹ in formula (I) and formula (a).

Examples of the alkylsulfonyl group constituting X ³ in formula (IV) and formula (d) include the same groups as the alkylsulfonyl group constituting X ¹ in formula (I) and formula (a). .

Examples of the alkoxy group constituting X ³ in formula (IV) and formula (d) include the same alkoxy group constituting X ¹ in formula (I) and formula (a).

Examples of the acyl group that constitutes X ³ in formula (IV) and formula (d) include the same acyl groups as those that constitute X ¹ in formula (I) and formula (a).

Examples of the alkyl ester group constituting X ³ in formula (IV) and formula (d) include the same alkyl ester group constituting X ¹ in formula (I) and formula (a).

Examples of the halogenated alkyl group constituting X ³ in formula (IV) and formula (d) include the same groups as the halogenated alkyl group constituting X ¹ in formula (I) and formula (a).

Among the above, X ³ is preferably a halogen atom, more preferably a chlorine atom, and more preferably the same as X ¹ .

The proportion of monomer units (IV) in copolymer B is not particularly limited. When all monomer units in copolymer B are set to 100 mol%, it can be, for example, 30 mol% or more. It is preferably 40 mol% or more, more preferably 45 mol% or more, and it can be, for example, 70 mol% or less, preferably 60 mol% or less, and preferably 55 mol% or less.

[Single unit (V)]

Here, the monomer unit (V) is derived from the following formula (e): 『Chemical 20』 [In formula (e), R ⁵ to R ⁷ , r and s are the same as in formula (V). 〕The structural unit of the monomer (e) shown.

The alkyl group constituting R ⁵ and R ⁶ in formula (V) and formula (e) is not particularly limited, and examples thereof include unsubstituted alkyl groups having 1 to 5 carbon atoms. Among them, the alkyl group constituting R ⁵ and R ⁶ is preferably a methyl group or an ethyl group.

The halogen atom constituting R ⁶ in the formula (V) and the formula (e) is not particularly limited, and examples include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like. Among them, as the halogen atom, a fluorine atom is preferred.

The halogenated alkyl group constituting R ⁶ in formula (V) and formula (e) is not particularly limited, and examples thereof include fluoroalkyl groups having 1 to 5 carbon atoms. Among these, as the halogenated alkyl group, a perfluoroalkyl group having 1 to 5 carbon atoms is preferred, and a trifluoromethyl group is preferred.

The hydroxyl halide group constituting R ⁶ in formula (V) and formula (e) is not particularly limited, and examples thereof include: hydroxyl chloride group (-C(=O)-Cl), hydroxyl fluoride group (- C(=O)-F), acyl bromide group (-C(=O)-Br), etc.

The unsubstituted alkyl group constituting R ⁷ in formula (V) and formula (e) is not particularly limited, and examples thereof include unsubstituted alkyl groups having 1 to 5 carbon atoms. Among them, the unsubstituted alkyl group constituting R ⁷ is preferably a methyl group or an ethyl group.

The alkyl group substituted with a fluorine atom to obtain R ⁷ in the formula (V) and the formula (e) is not particularly limited. Examples include those in which part or all of the hydrogen atoms in the alkyl group have been replaced with fluorine atoms. The basis of the substituted structure.

In formula (V) and formula (e), when r is 2 or more, each R ⁶ may be the same as each other or different. Furthermore, when s is 2 or more, each R ⁷ may be the same as each other or may be different.

In addition, for formula (V) and formula (e), r=5 (that is, s=0) is preferred.

When there are a plurality of R ⁶ and/or R ⁷ in formula (V) and formula (e), it is preferable that all of them are hydrogen atoms.

The monomer (e) represented by the formula (e) is not particularly limited, and examples thereof include α-methylstyrene (AMS) such as the following monomers (e-1) to (e-12) and its derivatives.

"Chemical 21"

In addition, from the viewpoint of improving the ease of preparation of the copolymer B and the cleavage property of the main chain when irradiating an electron beam or the like, as the monomer (e) represented by the formula (e), α-methyl Styrene (e-1) is preferred. That is, copolymer B preferably has α-methylstyrene units.

The proportion of monomer units (V) in copolymer B is not particularly limited. When all monomer units in copolymer B are set to 100 mol%, it can be, for example, 30 mol% or more, and 40 mol%. Mol% or more is preferred, and 45 mol% or more is more preferred. For example, the content may be 70 mol% or less, 60 mol% or less is preferred, and 55 mol% or less is preferred.

[Characteristics of copolymer B]

- Weight average molecular weight (Mw) -

The weight average molecular weight (Mw) of copolymer B is preferably 100,000 or more, more preferably 125,000 or more, more preferably 150,000 or more, and 600,000 or less, preferably 500,000 or less, and more preferably 300,000 or less. .

- Number average molecular weight (Mn) -

The number average molecular weight (Mn) of the copolymer B is preferably 100,000 or more, more preferably 110,000 or more, and 300,000 or less, preferably 200,000 or less, and more preferably 150,000 or less.

-Molecular weight distribution (Mw/Mn)-

The molecular weight distribution (Mw/Mn) of copolymer B is preferably above 1.20, preferably above 1.25, more preferably above 1.30, preferably below 2.00, preferably below 1.80, and preferably below 1.60. good.

[Proportion of copolymer B]

The content ratio of the copolymer B in the copolymer mixture is preferably 60 mass% or more, more preferably 70 mass% or more, and 75 mass% when the total of all components of the copolymer mixture is 100 mass%. % or more is more preferred, 99 mass% or less is more preferred, 95 mass% or less is more preferred, 90 mass% or less is more preferred, and 85 mass% or less is more preferred.

If the proportion of the copolymer B in the copolymer mixture is equal to or higher than the above-mentioned lower limit when the total of all components of the copolymer mixture is 100% by mass, the sensitivity to ionizing radiation and the like can be improved.

On the other hand, if the proportion of copolymer B in the copolymer mixture is less than the above upper limit when the sum of all components of the copolymer mixture is 100% by mass, the clarity of the photoresist pattern can be improved.

[Preparation method of copolymer B]

The preparation method of copolymer B is not particularly limited. For example, the copolymer B having the monomer unit (IV) and the monomer unit (V) mentioned above can be obtained by containing the monomer (d), the monomer (e) and the monomer capable of being combined with these monomers. It is prepared by polymerizing a monomer composition of any monomer that is copolymerized, recovering the obtained copolymer and optionally purifying it. Here, the polymerization method and the purification method are not particularly limited, and may be the same as those described in the above item "Preparation method of copolymer". Furthermore, as the polymerization method and the purification method, conventionally well-known methods such as suspension polymerization and solution polymerization can also be used. In addition, when preparing copolymer B, a polymerization initiator may also be used.

(Positive photoresist composition)

The positive photoresist composition of the present invention includes the copolymer of the present invention or the copolymer mixture of the present invention and a solvent, optionally further including known additives that can be blended into the photoresist composition. Specifically, the positive photoresist composition of the present invention contains, for example, any one of (A) to (C) shown below and a solvent. (A) The copolymer of the present invention (B) A copolymer mixture including copolymer A and copolymer B, wherein copolymer A is the copolymer of the present invention, and the surface free energy of copolymer B is equal to the surface free energy of copolymer A. The difference in free energy is more than 3 mJ/m ² (C) A copolymer mixture including copolymer A and copolymer B, wherein copolymer A is the copolymer of the present invention, and copolymer B has the following formula (IV ): "Chemical 22" [In the formula (IV), L ² is a divalent linking group having a fluorine atom, Ar ² is an aromatic ring group which may have a substituent, and X ³ is a halogen atom, a cyano group, an alkylsulfonyl group, or an alkoxy group. group, nitro group, acyl group, alkyl ester group or haloalkyl group. 〕The monomer unit (IV) shown is, and the following formula (V): 『Chemical 23』 [In the formula (V), R ⁵ is an alkyl group, R ⁶ is a hydrogen atom, an alkyl group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a carboxyl group or a halogenated carboxyl group, and R ⁷ is a hydrogen atom, an unsubstituted alkyl group or a fluorinated alkyl group. For atom-substituted alkyl groups, r and s are integers from 0 to 5, and r+s=5. 〕Single unit (V) shown

Since the copolymer of the present invention and the copolymer mixture of the present invention can ensure the clarity of the photoresist pattern while improving the pattern collapse resistance, if it is a positive photoresist of the present invention containing the copolymer or the copolymer mixture, The composition can form a photoresist pattern that is highly resistant to pattern collapse while ensuring clarity.

The positive-type photoresist composition of the present invention preferably does not substantially contain components with a weight-average molecular weight of less than 1,000. Specifically, the positive-type photoresist composition contains components with a weight-average molecular weight of less than 1,000 in a proportion of less than 1,000. 0.05% by mass, preferably less than 0.01% by mass, preferably less than 0.001% by mass.

If there is substantially no component with a weight average molecular weight of less than 1,000, the clarity of the photoresist pattern can be improved.

〈Copolymer, copolymer mixture〉

Since the details of the copolymer of the present invention and the copolymer mixture (copolymer A and copolymer B) of the present invention have been described above, description thereof will be omitted here.

[Proportion of copolymer in embodiment (A)]

When the total content of all components of the positive photoresist composition is 100% by mass, the content ratio of the copolymer in the positive photoresist composition is preferably 0.5 mass% or more, and more preferably 1 mass% or more. Preferably, it is more than 1.5 mass%, more preferably not more than 15 mass%, more preferably not more than 10 mass%, more preferably not more than 5 mass%.

[Proportion of copolymer mixture in embodiments (B) and (C)]

In the case where the positive photoresist composition includes a copolymer mixture (that is, in the case where the positive photoresist composition includes copolymer A and copolymer B), the copolymer mixture in the positive photoresist composition When the total content of all components of the positive photoresist composition is 100% by mass, the content ratio is preferably 0.5% by mass or more, more preferably 1% by mass or more, and more preferably 1.5% by mass or more. In addition, the content is preferably 15 mass% or less, more preferably 10 mass% or less, and more preferably 5 mass% or less.

〈solvent〉

The solvent is not particularly limited as long as it can dissolve the copolymer of the present invention and the copolymer A and copolymer B in the copolymer mixture. For example, known solvents such as those described in Japanese Patent No. 5938536 can be used. Solvent. Among them, from the perspective of obtaining a positive photoresist composition with a moderate viscosity to improve the coatability of the positive photoresist composition, as solvents, methoxybenzene, propylene glycol monomethyl ether acetate (PGMEA), Cyclopentanone, cyclohexanone or isopentyl acetate are preferred.

〈Preparation of positive photoresist composition〉

The positive photoresist composition can be prepared by mixing the copolymer or copolymer mixture (copolymer A and copolymer B) of the present invention, a solvent and optionally known additives. The mixing method is not particularly limited and may be mixed by well-known methods. Moreover, it can also be prepared by mixing each component and filtering the mixture.

〔Filter〕

Here, the filtration method of the mixture is not particularly limited. For example, a filter can be used for filtration. The filter is not particularly limited, and examples thereof include fluorocarbon-based, cellulose-based, nylon-based, polyester-based, and hydrocarbon-based filter membranes. Among them, it is from the viewpoint of effectively preventing impurities such as metal from being mixed into the positive photoresist composition from metal pipes and the like used in the copolymer of the present invention and in the preparation of copolymer A and copolymer B in the copolymer mixture. In terms of polyethylene, polypropylene, polytetrafluoroethylene, Teflon (registered trademark) and other polyfluorocarbons, tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer (PFA), nylon and polyethylene and Nylon composite membranes are preferred as the material constituting the filter. For example, the filter disclosed in US Patent No. 6103122 can also be used. In addition, you can also use those commercially available as Zeta Plus (registered trademark) 40Q manufactured by CUNO Incorporated as a filter. Furthermore, the filter may also contain an ion exchange resin with strong cationicity or weak cationicity. Here, the average particle size of the ion exchange resin is not particularly limited, but is preferably 2 μm or more and 10 μm or less. Examples of the cation exchange resin include: sulfonated phenol-formaldehyde condensate, sulfonated phenol-benzaldehyde condensate, sulfonated styrene/divinylbenzene copolymer, sulfonated methyl Acrylic acid/divinylbenzene copolymer and other types of polymers containing sulfonic acid or carboxylic acid groups. The cation exchange resin is supplied with H ⁺ counter ions, NH ₄ ⁺ counter ions, or alkali metal counter ions such as K ⁺ and Na ⁺ counter ions. Furthermore, the cation exchange resin preferably has hydrogen counter ions. Examples of such a cation exchange resin include Microlite (registered trademark) PrCH of Purolite Corporation, a sulfonated styrene/divinylbenzene copolymer having H ⁺ counter ions. This cation exchange resin is commercially available as AMBERLYST (registered trademark) by Rohm and Haas.

The pore size of the filter is preferably 0.001 μm or more and 1 μm or less. If the pore size of the filter is within the above range, impurities such as metal can be sufficiently prevented from being mixed into the positive photoresist composition.

(Photoresist pattern formation method)

Here, the positive photoresist composition of the present invention described above can be suitably used for photoresist pattern formation. Moreover, the photoresist pattern forming method at least includes: a step of forming a photoresist film using the positive photoresist composition of the present invention described above (photoresist film forming step), and a step of exposing the photoresist film (exposure step) ), and the process of developing the exposed photoresist film (development process).

In addition, the photoresist pattern forming method may further include processes other than the above-mentioned photoresist film forming process, exposure process and development process. Specifically, the photoresist pattern forming method may include a step of forming an underlayer film on the substrate on which the photoresist film is formed (underlayer film forming step) before the photoresist film forming step. Furthermore, the photoresist pattern forming method may also include a process of heating the exposed photoresist film (post-exposure bake (PEB) process) between the exposure process and the development process. Furthermore, the photoresist pattern forming method may further include a step of removing the developer (developer removal step) after the development step. Moreover, after forming the photoresist pattern through the photoresist pattern forming method, a process of etching the underlying film and/or the substrate (etching process) may also be included.

In this method of forming a photoresist pattern, since the positive photoresist composition of the present invention is used as the positive photoresist composition, it is possible to form a photoresist pattern with high resistance to pattern collapse while ensuring clarity.

<Underlayer film formation process>

In the underlayer film forming step, which may be optionally performed before the photoresist film forming step, the underlayer film is formed on the substrate. By providing an underlayer film on the substrate, the surface of the substrate is hydrophobicized. Thereby, the affinity between the substrate and the photoresist film can be improved, and the adhesion between the substrate and the photoresist film can be improved. The lower film may be an inorganic lower layer film or an organic lower layer film.

The inorganic underlayer film can be formed by applying an inorganic material on a substrate and firing it. Examples of inorganic materials include silicon-based materials.

The organic underlayer film can be formed by applying an organic material on a substrate to form a coating film and drying it. The organic material is not limited to those that are sensitive to light or electron beams. For example, photoresist materials or resin materials generally used in the semiconductor field and liquid crystal field can be used. Among them, as an organic material, a material capable of forming an organic underlying film capable of etching, especially dry etching, is preferred. If it is such an organic material, the organic lower layer film can be etched using the pattern formed by processing the photoresist film to transfer the pattern to the lower layer film to form the pattern of the lower layer film. Among them, the organic material is preferably a material that can form an organic underlayer film that can be etched by oxygen plasma etching or the like. Examples of organic materials used in the formation of organic underlayer films include AL412 from Brewer Science.

The organic material described above can be coated by conventionally well-known methods such as spin coating or use of a spinner. Furthermore, the method for drying the coating film may be any method that can volatilize the solvent contained in the organic material, and examples thereof include a baking method. At this time, the baking conditions are not particularly limited, but the baking temperature is preferably 80°C or higher and 300°C or lower, and the baking temperature is preferably 200°C or higher and 300°C or lower. Moreover, the baking time is preferably 30 seconds or more, 60 seconds or more, preferably 500 seconds or less, 400 seconds or less, more preferably 300 seconds or less, especially 180 seconds or less. good. Furthermore, the thickness of the lower layer film after drying of the coating film is not particularly limited, but is preferably 10 nm or more and 100 nm or less.

[Substrate]

Here, as the substrate on which the underlying film or the photoresist film is formed in the photoresist pattern forming method, there is no particular limitation. Examples of substrates that can be used include: a substrate having an insulating layer and copper disposed on the insulating layer, which is used in the manufacture of printed circuit boards. Foil substrates, and blank masks with a light-shielding layer formed on the substrate.

Examples of the material of the substrate include metals (silicon, copper, chromium, iron, aluminum, etc.), glass, inorganic substances such as titanium oxide, silicon dioxide (SiO ₂ ), silica, and mica; nitrides such as SiN; SiON, etc. Oxygen nitride; organic matter such as acrylic, polystyrene, cellulose, cellulose acetate, phenolic resin, etc. Among them, metal is preferred as the material of the substrate. By using, for example, a silicon substrate, a silicon dioxide substrate, or a copper substrate as a substrate, preferably a silicon substrate or a silicon dioxide substrate, a cylindrical structure can be formed.

The size and shape of the substrate are not particularly limited. In addition, the surface of the substrate may be smooth, may have a curved surface, an uneven shape, or may be a sheet-shaped substrate.

Surface treatment can also be applied to the surface of the substrate if required. For example, if the substrate has a hydroxyl group on the surface layer of the substrate, a silane-based coupling agent that can react with the hydroxyl group may be used for surface treatment of the substrate. Thereby, the surface layer of the substrate is changed from hydrophilic to hydrophobic, thereby improving the adhesion between the substrate and the underlying film or the substrate and the photoresist layer. At this time, the silane-based coupling agent is not particularly limited, but hexamethyldisilazane is preferred.

<Photoresist film formation process>

In the photoresist film forming step, the positive photoresist composition of the present invention is coated on a workpiece such as a substrate processed with a photoresist pattern (on the underlayer film when an underlayer film is formed). The coated positive photoresist composition is dried to form a photoresist film.

The coating method and drying method of the positive photoresist composition are not particularly limited, and methods commonly used in the formation of photoresist films can be used. Among them, heating (prebaking) is preferred as a drying method, and from the viewpoint of increasing the film density of the photoresist film, the prebaking temperature is preferably 100°C or higher, and more preferably 120°C or higher. , preferably above 140℃. Furthermore, from the viewpoint of reducing changes in the molecular weight and molecular weight distribution of the copolymer of the present invention and the copolymer A and copolymer B in the copolymer mixture of the present invention in the photoresist film before and after prebaking, prebaking is required. The baking temperature is preferably below 250°C, preferably below 220°C, and even more preferably below 200°C. Furthermore, from the perspective of increasing the film density of the photoresist film formed by prebaking, the pre-baking time is preferably 10 seconds or more, 20 seconds or more is more preferred, and 30 seconds or more is preferred. For the better. Furthermore, from the viewpoint of further reducing changes in the molecular weight and molecular weight distribution of the copolymer of the present invention and the copolymer A and copolymer B in the copolymer mixture of the present invention in the photoresist film before and after prebaking, The pre-baking time is preferably less than 10 minutes, more preferably less than 5 minutes, and even more preferably less than 3 minutes.

〈Exposure process〉

In the exposure process, the photoresist film formed in the photoresist film forming process is irradiated with ionizing radiation or the like to draw a desired pattern. In addition, a known drawing device such as an electron beam drawing device or an EUV exposure device can be used for electron beam irradiation.

〈Post-exposure baking process〉

In an optional post-exposure baking process, the photoresist film exposed in the exposure process is heated. If a post-exposure baking process is implemented, the surface roughness of the photoresist pattern can be reduced.

Here, the heating temperature is preferably 70°C or higher, more preferably 80°C or higher, more preferably 90°C or higher, and preferably 200°C or lower, preferably 170°C or lower, and more preferably 150°C or lower. good. If the heating temperature is within the above range, the surface roughness of the photoresist pattern can be well reduced while improving the clarity of the photoresist pattern.

The time for heating the photoresist film (heating time) in the post-exposure baking process is preferably 10 seconds or more, more preferably 20 seconds or more, and more preferably 30 seconds or more. If the heating time is more than 10 seconds, the surface roughness of the photoresist pattern can be fully reduced while further improving the clarity of the photoresist pattern. On the other hand, from the viewpoint of production efficiency, for example, the heating time is preferably 10 minutes or less, more preferably 5 minutes or less, and more preferably 3 minutes or less.

The method of heating the photoresist film in the post-exposure baking process is not particularly limited. For example, the method of heating the photoresist film with a heating plate, the method of heating the photoresist film in an oven, the method of heating the photoresist film The method of blowing hot air through the film.

〈Development process〉

In the development process, the exposed photoresist film (when performing the post-exposure baking process, the exposed and heated photoresist film) is developed to form a developed film on the workpiece.

Here, the photoresist film can be developed, for example, by contacting the photoresist film with a developer. The method of bringing the photoresist film into contact with the developer is not particularly limited, and known methods such as immersing the photoresist film in the developer or applying the developer to the photoresist film can be used.

[Developer]

The developer can be appropriately selected according to the properties of the copolymer of the present invention and the copolymer A and copolymer B in the copolymer mixture of the present invention. Specifically, when selecting a developer, it is preferable to select a developer that does not dissolve the photoresist film before the exposure process but can dissolve the exposed portion of the photoresist film that has undergone the exposure process. In addition, one type of developer may be used alone, or two or more types may be mixed and used at any ratio.

Furthermore, as the developer, for example, 1,1,1,2,3,4,4,5,5,5-decafluoropentane (CF ₃ CFHCFHCF ₂ CF ₃ ), 1,1,1,2 can be used ,2,3,3,4,4,5,5,6,6-tridecafluorohexane, 1,1,1,2,2,3,4,5,5,5-decafluoropentane, 1,1,1,3,3-pentafluorobutane, 1,1,1,2,2,3,3,4,4-nonafluorohexane and other hydrofluorocarbons, 2,2-dichloro- 1,1,1-trifluoroethane, 1,1-dichloro-1-fluoroethane, 1,1-dichloro-2,2,3,3,3-pentafluoropropane (CF ₃ CF ₂ CHCl ₂ ), 1,3-dichloro-1,1,2,2,3-pentafluoropropane (CClF ₂ CF ₂ CHClF) and other hydrofluorochlorocarbons, methyl nonafluorobutyl ether (CF ₃ CF ₂ CF ₂ CF ₂ OCH ₃ ), methyl nonafluoroisobutyl ether, ethyl nonafluorobutyl ether (CF ₃ CF ₂ CF ₂ CF ₂ OC ₂ H ₅ ), ethyl nonafluoroisobutyl ether, perfluorohexyl Methyl ether (CF ₃ CF ₂ CF(OCH ₃ )C ₃ F ₇ ) and other hydrofluoroethers, as well as CF ₄ , C ₂ F ₆ , C ₃ F ₈ , C ₄ F ₈ , C ₄ F ₁₀ , C ₅ F ₁₂ , C ₆ F ₁₂ , C ₆ F ₁₄ , C ₇ F ₁₄ , C ₇ F ₁₆ , C ₈ F ₁₈ , C ₉ F ₂₀ and other perfluorocarbons and other fluorine-based solvents; methanol, ethanol, 1-propanol, 2-Propanol (isopropanol), 1-butanol, 2-butanol, 1-pentanol, 2-pentanol, 3-pentanol and other alcohols; ethyl acetate, hexyl acetate and other alkyl groups Acid esters; mixtures of fluorine-based solvents and alcohols; mixtures of fluorine-based solvents and acetate esters with alkyl groups; mixtures of alcohols and acetate esters with alkyl groups; fluorine-based solvents, alcohols, and acetate esters with alkyl groups mixture; etc. Among these, from the viewpoint of further improving the clarity of the photoresist pattern, it is preferable to use an alcohol such as 2-butanol or isopropyl alcohol for development.

In addition, the temperature of the developer during development is not particularly limited, but may be, for example, 5°C or more and 40°C or less. Moreover, the development time can be set to 10 seconds or more and 4 minutes or less, for example.

〈Developer removal process〉

In the developer removal step optionally included in the photoresist pattern forming method, the developer is removed from the developed photoresist film to form a photoresist pattern on the workpiece.

The developer can be removed by blowing with gas such as nitrogen or rinsing with a rinsing solution.

Here, in the rinse treatment, the method of bringing the developed photoresist film into contact with the rinse solution is not particularly limited. The photoresist film can be immersed in the rinse solution or the rinse solution can be applied to Known methods such as photoresist film. Specific examples of the rinse solution include, for example, the same developers as those exemplified in the “development step”, hydrocarbon solvents such as octane and heptane, and water. Here, the rinse liquid may also contain surfactants. Furthermore, when selecting a rinse solution, it is better to select a rinse solution that is less likely to dissolve the photoresist film before the exposure process than the developer used in the development process and that is easy to mix with the developer.

In addition, the temperature of the rinse liquid during rinse is not particularly limited, but may be, for example, 5°C or more and 40°C or less. Moreover, the rinsing time can be set to 5 seconds or more and 3 minutes or less, for example.

The developer and rinse solutions mentioned above can also be filtered before use. Furthermore, as a filtration method, for example, the filtration method using a filter described in the item "Preparation of a positive photoresist composition" mentioned above can be cited.

<Etching process>

In an optional etching process, the above-mentioned photoresist pattern is used as a mask to etch the underlying film and/or the substrate, and form a pattern on the underlying film and/or substrate.

At this time, the number of etching times is not particularly limited and may be once or multiple times. Furthermore, the etching may be dry etching or wet etching, but dry etching is preferred. Dry etching can be performed using well-known dry etching equipment. The etching gas used in dry etching can be appropriately selected according to the elemental composition of the underlying film or substrate to be etched. Examples of the etching gas include fluorine-based gases such as CHF ₃ , CF ₄ , C ₂ F ₆ , C ₃ F ₈ , and SF ₆ ; chlorine-based gases such as Cl ₂ and BCl ₃ ; O ₂ , O ₃ , and H ₂ O Oxygen series _gases ; H ₂ , NH ₃ , CO, CO ₂ , CH ₄ , C 2 H 2 , C ₂ H ₄ , C ₂ H ₆ , C ₃ H ₄ , C ₃ H ₆ , C _{3 H 8} , HF , HI, HBr, HCl, NO, BCl ₃ and other reducing gases; He, N ₂ , Ar and other inert gases (inert gas); etc. One type of these gases may be used alone, or two or more types may be mixed and used. In addition, oxygen-based gas is usually used for dry etching of the inorganic underlying film. In addition, fluorine-based gas is usually used for dry etching of substrates, and it is suitable to use a mixture of fluorine-based gas and inert gas.

Furthermore, if necessary, the underlying film remaining on the substrate may also be removed before etching the substrate or after etching the substrate. When the lower layer film is removed before etching the substrate, the lower layer film may be a patterned lower layer film or an unpatterned lower layer film.

Here, as a method of removing the lower layer film, for example, the dry etching described above can be used. Furthermore, in the case of an inorganic underlayer film, the underlayer film can be removed by bringing a liquid such as an alkaline liquid or an acidic liquid, preferably an alkaline liquid, into contact with the underlayer film. Here, the alkaline liquid is not particularly limited, and examples thereof include alkaline hydrogen peroxide aqueous solution. The method for removing the lower layer film by wet peeling using an alkaline hydrogen peroxide aqueous solution is not particularly limited as long as the lower layer film and the alkaline hydrogen peroxide aqueous solution can be contacted for a certain period of time under heating conditions, and examples thereof include For example: the method of immersing the lower film in a heated alkaline hydrogen peroxide aqueous solution, the method of spraying the lower film with an alkaline hydrogen peroxide aqueous solution in a heated environment, and the method of applying the heated alkaline hydrogen peroxide aqueous solution to the lower layer Membrane methods, etc. After performing any of these methods, the substrate is washed with water and dried, thereby obtaining a substrate from which the underlying film has been removed.

An example of a photoresist pattern forming method using the positive photoresist composition of the present invention and an etching method of an underlying film and a substrate using the formed photoresist pattern will be described below. However, since the substrate used in the following examples and the conditions in each process are the same as the substrates and conditions in each process described above, descriptions thereof are omitted below. In addition, the photoresist pattern forming method is not limited to the method disclosed in the following example.

An example of a photoresist pattern forming method is a photoresist pattern forming method using electron beam or EUV, which includes the above-mentioned underlayer film formation process, photoresist film formation process, exposure process, development process and developer removal process. Furthermore, an example of the etching method is to use a photoresist pattern formed by a photoresist pattern forming method as a mask, and includes an etching process.

Specifically, in the underlayer film forming step, an inorganic underlayer film is formed by applying an inorganic material on the substrate and firing.

Next, in the photoresist film forming process, the positive photoresist composition of the present invention is coated on the inorganic underlayer film formed in the underlayer film forming process and dried to form a photoresist film.

Thereafter, in the exposure process, the photoresist film formed in the photoresist film forming process is irradiated with EUV to draw a desired pattern.

Next, in the developing process, the photoresist film exposed in the exposure process is brought into contact with a developer to develop the photoresist film and form a photoresist pattern on the underlying film.

Then, in the developer removal process, the photoresist film developed in the development process is brought into contact with the rinse solution to rinse the developed photoresist film.

Thereafter, in the etching process, the lower layer film is etched using the above-mentioned photoresist pattern as a mask, and a pattern is formed on the lower layer film.

Subsequently, the substrate is etched using the patterned lower film as a mask to form a pattern on the substrate.

<Etching resistance of photoresist film>

The photoresist film obtained by the above-described photoresist pattern forming method has excellent etching resistance, especially dry etching resistance. In addition, the greater the ratio of the carbon content per unit volume of the copolymer A and copolymer B in the copolymer mixture of the present invention included in the positive photoresist composition, the photoresist film will have dry The corrosion resistance tends to be better.

〈Stack〉

The stack obtained through the above-described photoresist pattern forming method includes a substrate and a photoresist film formed on the substrate. Furthermore, such a stacked body can be suitably used as a printed circuit board.

"Example"

The present invention is specifically described below based on examples, but the present invention is not limited to these examples.

In addition, in the Examples, Comparative Examples and Preparation Examples, the proportion of monomer units in the copolymer, the number average molecular weight, weight average molecular weight, molecular weight distribution and surface free energy of the copolymer were measured by the following methods. Here, the surface free energy was measured only for Examples 1, 2, 5, 10, 11 and Preparation Examples 1 and 2.

Furthermore, in the examples and comparative examples, the γ value, Eth, pattern collapse resistance and photoresist residue were measured or evaluated by the following methods.

〈Proportion of monomer units in copolymer〉

For the copolymer obtained in the preparation example, the ratio of the monomer units in the copolymer was calculated using the ¹ H-NMR method.

Specifically, the copolymer obtained in the preparation example was dissolved in deuterated chloroform 99.8% (manufactured by FUJIFILM Wako Pure Chemical Corporation) so as to become 10% by mass, and measured using a nuclear magnetic resonance device (manufactured by JEOL Ltd., 400 mHz). For this solution, the proportion of monomer units in the copolymer is calculated from the measurement results.

〈Number average molecular weight, weight average molecular weight and molecular weight distribution〉

For the copolymer A and copolymer B obtained in the Examples, Comparative Examples and Preparation Examples, the number average molecular weight (Mn) and the weight average molecular weight (Mw) were measured using gel permeation chromatography, and the molecular weight distribution (Mw/ Mn).

Specifically, a gel permeation chromatography (HLC-8220 manufactured by Tosoh Corporation) was used, and tetrahydrofuran was used as the eluent to determine the number average molecular weight (Mn) of the copolymer in terms of standard polystyrene conversion values and Weight average molecular weight (Mw). Then, the molecular weight distribution (Mw/Mn) is calculated. In addition, in each of copolymer A and copolymer B, it was confirmed that components with a weight average molecular weight less than 1000 were substantially absent (less than 0.05 mass %).

〈Surface free energy〉

The surface free energy was measured using the copolymers obtained in Examples 1, 2, 5, 10, 11 and Preparation Examples 1 and 2.

Specifically, the copolymer was first dissolved in isoamyl acetate as a solvent to prepare a positive photoresist composition with a concentration of 2 mass %. Subsequently, a spin coater (MS-A150 manufactured by MIKASA) was used to coat the positive photoresist composition on a 4-inch-diameter silicon wafer to a thickness of 50 nm. Subsequently, the coated positive photoresist composition is heated on a hot plate at a temperature of 170°C for 1 minute to form a thin film (photoresist film) on the silicon wafer. For the obtained thin film (photoresist film), use a contact angle meter (Drop Master 700 manufactured by Kyowa Interface Science) to measure the surface tension, polarity term (p) and dispersion force term (d) under the following conditions, which are known 2 The contact angle of two solvents (water and diiodomethane) was evaluated using the Owens-Wendt (Extended Fowkes Method) method to obtain the surface free energy, and the film (photoresist film) was calculated. ) surface free energy.

"Measurement Conditions of Contact Angle" Needle: Metal needle 22G (water), Teflon (registered trademark) coating 22G (diiodomethane) Standby time: 1000 ms Liquid volume: 1.8 μL Liquid identification: water 50 dat, diiodomethane 100 dat Temperature: 23℃

〈γ value〉

The γ value was measured using the positive photoresist compositions obtained in the examples and comparative examples.

Specifically, first, a spin coater (MS-A150 manufactured by MIKASA) was used to coat a positive photoresist composition on a 4-inch-diameter silicon wafer to a thickness of 50 nm. Subsequently, the coated positive photoresist composition is heated on a hot plate at a temperature of 170° C. for 1 minute to form a photoresist film on the silicon wafer (photoresist film forming step). Then, using an electron beam drawing device (ELIONIX Co., Ltd., ELS-S50), a plurality of patterns (size 500 μm × 500 μm) with different electron beam irradiation amounts are drawn on the photoresist film (exposure process). , heat the exposed photoresist film on a hot plate at 100°C for 1 minute (post-exposure baking process). For the heated photoresist film, use isopropyl alcohol (IPA) as a developer and develop at a temperature of 23°C for 1 minute (development process). Thereafter, the developer is removed by blowing nitrogen (developer removal step).

In addition, the electron beam irradiation dose was varied by 4 μC/cm 2 in the range of 4 μC/cm ² to 200 μC/cm ^{2 .} Secondly, an optical film thickness meter (Lambda Ace manufactured by Screen Semiconductor Solutions) was used to measure the thickness of the photoresist film in the depicted part, and a common logarithm of the total irradiation dose of the electron beam and the value of the photoresist film after development were produced. Sensitivity curve of the relationship between the remaining film rate (= film thickness of the photoresist film after development/film thickness of the photoresist film formed on the silicon wafer).

Find the γ value using the following equation. The results are disclosed in Table 2 and Table 3. In addition, in the following formula, E ₀ is a function of fitting the sensitivity curve to a quadratic function in the range of the remaining film rate from 0.20 to 0.80, and comparing the obtained quadratic function (the common logarithm of the remaining film rate and the total irradiation amount ) is substituted into the logarithm of the total irradiation dose obtained when the residual film rate is 0. Furthermore, _E1 is used to create a straight line (an approximate line of the slope of the sensitivity curve) connecting the point where the residual film rate is 0 and the point where the residual film rate is 0.50 on the obtained quadratic function, and to calculate the obtained straight line (residual film rate). The logarithm of the total irradiation dose obtained when the residual film rate is 1.00. Furthermore, the following formula represents the slope of the straight line between the remaining film ratio of 0 and the remaining film ratio of 1.00. In addition, the larger the value of γ, the greater the slope of the sensitivity curve, and the better the formation of clear patterns. Here, if the γ value is 10 or more, it can be said that the clarity of the photoresist pattern is ensured. "Mathematical formula 1"

〈Eth〉

According to the evaluation method of "γ value", a photoresist film is formed on the silicon wafer. The initial thickness T ₀ of the obtained photoresist film was measured with an optical film thickness meter (manufactured by Screen Semiconductor Solutions, Lambda Ace). Furthermore, the total electron beam irradiation dose Eth (μC/cm ² ) at which the remaining film rate of the straight line (approximate line of the slope of the sensitivity curve) obtained when the γ value is calculated becomes 0 is determined. The results are disclosed in Table 2 and Table 3. The smaller the value of Eth, the higher the sensitivity of the photoresist film and the higher the efficiency of forming the photoresist pattern.

〈Pattern collapse resistance〉

The positive photoresist compositions obtained in Examples and Comparative Examples were used to evaluate pattern collapse resistance.

Specifically, first, a spin coater (MS-A150 manufactured by MIKASA) was used to coat a positive photoresist composition on a 4-inch-diameter silicon wafer to a thickness of 50 nm. Subsequently, the coated positive photoresist composition is heated on a hot plate at a temperature of 120° C. for 1 minute to form a photoresist film on the silicon wafer (photoresist film forming step). The thickness of the photoresist film is 50 nm. Then, the photoresist film was exposed at an optimal exposure amount (Eop) using an electron beam drawing device (ELIONIX Co., Ltd., ELS-S50) to draw a pattern (exposure process). Heat the exposed photoresist film on a hot plate at 90°C for 1 minute (post-exposure baking process). For the photoresist film after the post-exposure baking process, use isopropyl alcohol (IPA) as the developer and develop at a temperature of 23°C for 1 minute (development process). Thereafter, the developer is removed by blowing nitrogen to form a photoresist pattern (developer removal step).

Then, the presence or absence of pattern collapse of the formed photoresist pattern is observed. In addition, the optimal exposure (Eop) is set appropriately by setting a value of approximately 2 times Eth as a standard. Furthermore, the line width (unexposed area) and line spacing (exposed area) of the photoresist pattern were each set to 20 nm.

Then, the suppression of pattern collapse was evaluated based on the following criteria. The results are disclosed in Table 2 and Table 3. A: No pattern collapse B: Pattern collapse occurs in more than 1 and less than 3 places C: Pattern collapse occurred in 4 or more places

〈Photoresist residue〉

The positive photoresist compositions obtained in Examples and Comparative Examples were used to evaluate photoresist residues.

Specifically, a spin coater (MS-A150 manufactured by MIKASA) was first used to coat the positive photoresist composition on a 4-inch diameter silicon wafer. Subsequently, the coated positive photoresist composition is heated on a hot plate at a temperature of 180°C for 3 minutes to form a photoresist film with a thickness of 40 nm on the silicon wafer (photoresist film forming process). Then, the photoresist film was exposed at an optimal exposure amount (Eop) using an electron beam drawing device (ELIONIX Co., Ltd., ELS-S50) to draw a pattern (exposure process). Then, using isopropyl alcohol (IPA) as a developer, a development process (development process) was performed at a temperature of 23°C for 1 minute. Then, use a fluorine-based solvent with a surface tension of 13.6 mN/m (3M Company, Novec (registered trademark) 7100, methyl nonafluorobutyl ether, freezing point: -135°C, boiling point: 61°C) as a rinsing fluid. Wash for 10 seconds to form a photoresist pattern (developer removal process). Subsequently, a scanning electron microscope (SEM) was used to observe at a magnification of 100,000 times, and the extent to which the residue remained in the photoresist pattern was evaluated based on the following criteria. In addition, the residue remaining in the photoresist pattern can be confirmed in the SEM image as "dots" with high brightness compared with the line width pattern area without attached residue. The results are revealed in Table 2. A: No residue was found in the photoresist pattern of hp25 nm. B: Although there is very little residue in the hp25 nm photoresist pattern, it is within the allowable range. C: A lot of residue was found in the hp25 nm photoresist pattern and was outside the allowable range.

(Example 1)

〈Preparation of copolymer〉

It will contain 0.7207 g of α-chloroacrylic acid-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl ester (ACAFPh) as the monomer (a), and α as the monomer (b). -Chloroacrylic acid-2,2,3,3,4,4,4-heptafluorobutyl ester (ACAHFB) 2.5004 g, α-methylstyrene as monomer (c) 3.0000 g (combined ACAFPh and ACAHFB When the total is 1 equivalent, it is equivalent to approximately 2.34 equivalents), 0.0048 g of azobisisobutyronitrile as a polymerization initiator, and 1.5565 g of cyclopentanone as a solvent, the monomer composition A1 is placed in a glass container. The glass container was sealed and replaced with nitrogen, and stirred in a constant temperature bath at 78° C. for 6 hours in a nitrogen atmosphere.

After returning to room temperature and opening the glass container to the atmosphere, 10 g of THF was added to the obtained solution. Then, the solution to which THF was added was dropped into 100 g of MeOH as a solvent to precipitate the crude polymerization product. Thereafter, the solution containing the precipitated crude polymerization product was filtered through a Kiriyama funnel to obtain a white aggregate (copolymer A1). The ¹ H-NMR method was used to calculate the proportion of monomer units in the obtained copolymer A1. The result was that the copolymer A1 contained 10 mol% of α-chloroacrylic acid-1-phenyl-1-trifluoromethyl-2,2 , 2-trifluoroethyl ester unit, 40 mol% α-chloroacrylic acid-2,2,3,3,4,4,4-heptafluorobutyl ester unit, 50 mol% α-methylstyrene unit copolymer.

Thereafter, the number average molecular weight, weight average molecular weight, molecular weight distribution and surface free energy of the obtained copolymer A1 were measured. The results are revealed in Table 1.

〈Preparation of positive photoresist composition〉

The copolymer A1 prepared as described above was dissolved in isoamyl acetate as a solvent to prepare a positive photoresist composition with a concentration of 2 mass %.

For the obtained positive photoresist composition, the γ value, Eth, pattern collapse resistance and photoresist residue are measured or evaluated. The results are revealed in Table 2.

(Example 2)

In addition to the preparation of the copolymer, 1.4413 g of α-chloroacrylic acid-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl ester (ACAFPh) as monomer (a) was used, α-Chloroacrylic acid-2,2,3,3,4,4,4-heptafluorobutyl (ACAHFB) as monomer (b) 1.8753 g, α-methylstyrene as monomer (c) 3.0000 g (corresponding to approximately 2.34 equivalents when the sum of ACAFPh and ACAHFB is 1 equivalent), 0.0048 g of azobisisobutyronitrile as a polymerization initiator, and 1.5803 g of cyclopentanone as a solvent. Except for preparing copolymer A2 by replacing monomer composition A1 with compound A2, various operations, measurements and evaluations were carried out in accordance with the procedures of Example 1. The results are disclosed in Table 1 and Table 2.

(Example 3)

In addition to the preparation of the copolymer, 2.1620 g of α-chloroacrylic acid-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl ester (ACAFPh) as monomer (a) was used, α-Chloroacrylic acid-2,2,3,3,4,4,4-heptafluorobutyl (ACAHFB) as monomer (b) 1.2502 g, α-methylstyrene as monomer (c) 3.0000 g (equivalent to about 2.34 equivalents when the sum of ACAFPh and ACAHFB is 1 equivalent), 0.0048 g of azobisisobutyronitrile as a polymerization initiator, and 1.6042 g of cyclopentanone as a solvent. Except for preparing copolymer A3 by replacing monomer composition A1 with product A3, various operations, measurements and evaluations were carried out according to the operation of Example 1. The results are disclosed in Table 1 and Table 2.

(Example 4)

In addition to the preparation of the copolymer, 2.8826 g of α-chloroacrylic acid-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl ester (ACAFPh) as monomer (a) was used, α-Chloroacrylic acid-2,2,3,3,4,4,4-heptafluorobutyl (ACAHFB) as monomer (b) 0.6251 g, α-methylstyrene as monomer (c) 3.0000 g (equivalent to about 2.34 equivalents when the sum of ACAFPh and ACAHFB is 1 equivalent), 0.0048 g of azobisisobutyronitrile as a polymerization initiator, and 1.6281 g of cyclopentanone as a solvent. Except that copolymer A4 was prepared using product A4 instead of monomer composition A1, various operations, measurements, and evaluations were carried out according to the operation of Example 1. The results are disclosed in Table 1 and Table 2.

(Example 5)

In addition to the preparation of the copolymer, 0.7207 g of α-chloroacrylic acid-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl ester (ACAFPh) as monomer (a) was used, α-Chloroacrylic acid-2,2,3,3,3-pentafluoropropyl (ACAPFP) as monomer (b) 2.0711 g, α-methylstyrene as monomer (c) 3.0000 g (in the The sum of ACAFPh and ACAPFP is equivalent to approximately 2.34 equivalents when 1 equivalent), 0.0048 g of azobisisobutyronitrile as a polymerization initiator, and 1.4491 g of cyclopentanone as a solvent are used instead of the monomer composition A5. Except for preparing the copolymer A5 from the bulk composition A1, various operations, measurements, and evaluations were carried out according to the operation of Example 1. The results are disclosed in Table 1 and Table 2.

(Example 6)

In addition to the preparation of the copolymer, 1.4413 g of α-chloroacrylic acid-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl ester (ACAFPh) as monomer (a) was used, 1.5534 g of α-chloroacrylic acid-2,2,3,3,3-pentafluoropropyl (ACAPFP) as monomer (b), 3.0000 g of α-methylstyrene as monomer (c) (in the When the sum of ACAFPh and ACAPFP is 1 equivalent, it corresponds to about 2.34 equivalents), 0.0048 g of azobisisobutyronitrile as a polymerization initiator, and 1.4999 g of cyclopentanone as a solvent are used instead of the monomer composition A6. Except for preparing the copolymer A6 from the bulk composition A1, various operations, measurements, and evaluations were carried out according to the operation of Example 1. The results are disclosed in Table 1 and Table 2.

(Example 7)

In addition to the preparation of the copolymer, 2.1620 g of α-chloroacrylic acid-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl ester (ACAFPh) as monomer (a) was used, 1.0356 g of α-chloroacrylic acid-2,2,3,3,3-pentafluoropropyl (ACAPFP) as monomer (b), 3.0000 g of α-methylstyrene as monomer (c) (in the The sum of ACAFPh and ACAPFP is equivalent to about 2.34 equivalents when 1 equivalent), 0.0048 g of azobisisobutyronitrile as a polymerization initiator, and 1.5506 g of cyclopentanone as a solvent are used instead of the monomer composition A7. Except for preparing the copolymer A7 from the bulk composition A1, various operations, measurements, and evaluations were carried out according to the operation of Example 1. The results are disclosed in Table 1 and Table 2.

(Example 8)

In addition to the preparation of the copolymer, 2.8826 g of α-chloroacrylic acid-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl ester (ACAFPh) as monomer (a) was used, α-Chloroacrylic acid-2,2,3,3,3-pentafluoropropyl (ACAPFP) as monomer (b) 0.5178 g, α-methylstyrene as monomer (c) 3.0000 g (in the The sum of ACAFPh and ACAPFP is equivalent to approximately 2.34 equivalents when 1 equivalent), 0.0048 g of azobisisobutyronitrile as a polymerization initiator, and 1.6013 g of cyclopentanone as a solvent are used instead of the monomer composition A8. Except for preparing the copolymer A8 from the bulk composition A1, various operations, measurements, and evaluations were carried out according to the operation of Example 1. The results are disclosed in Table 1 and Table 2.

(Example 9)

In addition to the preparation of the copolymer, 0.7207 g of α-chloroacrylic acid-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl ester (ACAFPh) as monomer (a) was used, 1.6361 g of α-chloroacrylic acid-2,2,2-trifluoroethyl (ACATFE) as monomer (b), 3.0000 g of α-methylstyrene as monomer (c) (after combining ACAFPh and ACATFE When the total is 1 equivalent, it is equivalent to approximately 2.34 equivalents), 0.0048 g of azobisisobutyronitrile as a polymerization initiator, and 1.4021 g of cyclopentanone as a solvent, in place of the monomer composition A1. Except for preparing copolymer A9, various operations, measurements, and evaluations were performed as in Example 1. The results are disclosed in Table 1 and Table 2.

(Example 10)

In addition to the preparation of the copolymer, 0.5731 g of α-chloroacrylic acid-1-phenyl-2,2,2-trifluoroethyl ester (ACAHFPh) as monomer (a) and monomer (b) were used. 2.5004 g of α-chloroacrylic acid-2,2,2-trifluoroethyl ester (ACAHFB), 3.0000 g of α-methylstyrene as monomer (c) (when the sum of ACAHFPh and ACAHFB is 1 equivalent (corresponding to about 2.34 equivalents below), 0.0048 g of azobisisobutyronitrile as a polymerization initiator, and 1.5196 g of cyclopentanone as a solvent, except that the copolymer A10 was prepared instead of the monomer composition A1. Example 1 Operation Various operations, measurements, and evaluations were performed. The results are disclosed in Table 1 and Table 2.

(Example 11)

In addition to the preparation of the copolymer, 0.5731 g of α-chloroacrylic acid-1-phenyl-2,2,2-trifluoroethyl ester (ACAHFPh) as monomer (a) and monomer (b) were used. 2.0711 g of α-chloroacrylic acid-2,2,2-trifluoroethyl ester (ACAPFP), 3.0000 g of α-methylstyrene as monomer (c) (when the sum of ACAHFPh and ACAPFP is taken as 1 equivalent (corresponding to about 2.34 equivalents below), 0.0048 g of azobisisobutyronitrile as the polymerization initiator and 1.4122 g of cyclopentanone as the solvent were used instead of the monomer composition A1 to prepare the copolymer A11. Example 1 Operation Various operations, measurements, and evaluations were performed. The results are disclosed in Table 1 and Table 2.

(Example 12)

In addition to the preparation of the copolymer, 0.5731 g of α-chloroacrylic acid-1-phenyl-2,2,2-trifluoroethyl ester (ACAHFPh) as monomer (a) and monomer (b) were used. 1.6361 g of α-chloroacrylic acid-2,2,2-trifluoroethyl ester (ACATFE), 3.0000 g of α-methylstyrene as monomer (c) (when the sum of ACAHFPh and ACATFE is taken as 1 equivalent (corresponding to about 2.34 equivalents below), 0.0048 g of azobisisobutyronitrile as the polymerization initiator and 1.3781 g of cyclopentanone as the solvent were used instead of the monomer composition A1 to prepare the copolymer A12. Example 1 Operation Various operations, measurements, and evaluations were performed. The results are disclosed in Table 1 and Table 2.

(Example 13)

In addition to the preparation of the copolymer, α-chloroacrylic acid-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl ester (ACAFPh) 0.7221 g, α-Chloroacrylic acid-2,2,3,3,4,4,5,5,5-nonafluoropentyl (ACANFP) as monomer (b) 2.9394 g, α-methane as monomer (c) 3.0000 g of styrene (equivalent to about 2.34 equivalents when the sum of ACAFPh and ACANFP is 1 equivalent), 0.0067 g of azobisisobutyronitrile as a polymerization initiator, and 1.6587 g of cyclopentanone as a solvent Except for preparing copolymer A13 using monomer composition A13 instead of monomer composition A1, various operations, measurements, and evaluations were carried out according to the operation of Example 1. The results are disclosed in Table 1 and Table 2.

(Example 14)

In addition to the preparation of the copolymer, 1.4442 g of α-chloroacrylic acid-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl ester (ACAFPh) as monomer (a) was used, α-Chloroacrylic acid-2,2,3,3,4,4,5,5,5-nonafluoropentyl (ACANFP) as monomer (b) 2.3990 g, α-methyl as monomer (c) 3.0000 g of styrene (equivalent to about 2.34 equivalents when the sum of ACAFPh and ACANFP is 1 equivalent), 0.0066 g of azobisisobutyronitrile as a polymerization initiator, and 1.6556 g of cyclopentanone as a solvent Except for preparing copolymer A14 using monomer composition A14 instead of monomer composition A1, various operations, measurements, and evaluations were carried out according to the operation of Example 1. The results are disclosed in Table 1 and Table 2.

(Comparative example 1)

In addition to the preparation of the copolymer, 3.0000 g of α-chloroacrylic acid-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl ester (ACAFPh) as monomer (a) was used, Various operations were carried out as in Example 1 except that the copolymer A15 was prepared by replacing the monomer composition A1 with 0.0396 g of azobisisobutyronitrile as the polymerization initiator and 7.0924 g of cyclopentanone as the solvent. Measurement and evaluation. The results are disclosed in Table 1 and Table 2.

(Comparative example 2)

In addition to the preparation of the copolymer, 3.0000 g of α-chloroacrylic acid-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl ester (ACAFPh) as monomer (a) was used, A monomer consisting of 2.4930 g of α-methylstyrene as the monomer (c) (corresponding to approximately 2.34 equivalents when ACAFPh is defined as 1 equivalent) and 0.0040 g of azobisisobutyronitrile as the polymerization initiator. Except for preparing copolymer A16 using composition A16 instead of monomer composition A1, various operations, measurements, and evaluations were carried out according to the operation of Example 1. The results are disclosed in Table 1 and Table 2.

(Comparative example 3)

In addition to the preparation of the copolymer, 3.0000 g of α-chloroacrylic acid-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl ester (ACAFPh) as monomer (a) was used, 0.5389 g of α-chloroacrylic acid-2,2,3,3,3-pentafluoropropyl (ACAPFP) as monomer (b), 0.1980 g of azobisisobutyronitrile as polymerization initiator, and 0.1980 g of azobisisobutyronitrile as solvent. Various operations, measurements, and evaluations were performed according to the operation of Example 1, except that the monomer composition A17 of 8.9801 g of cyclopentanone was used instead of the monomer composition A1 to prepare the copolymer A17. The results are disclosed in Table 1 and Table 2.

(Comparative example 4)

In addition to the preparation of the copolymer, 3.0000 g of α-chloroacrylic acid-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl ester (ACAFPh) as monomer (a) was used, 0.6506 g of α-chloroacrylic acid-2,2,3,3,4,4,4-heptafluorobutyl ester (ACAHFB) as monomer (b), 0.1980 g of azobisisobutyronitrile as polymerization initiator Various operations, measurements, and evaluations were performed as in Example 1, except that copolymer A18 was prepared using monomer composition A18 containing 8.9801 g of cyclopentanone as the solvent instead of monomer composition A1. The results are disclosed in Table 1 and Table 2.

(Comparative example 5)

In addition to the preparation of the copolymer, 3.0000 g of α-chloroacrylic acid-2,2,3,3,3-pentafluoropropyl (ACAPFP) as monomer (b) and α-chloroacrylate as monomer (c) were used. - A single unit of 3.4764 g of methylstyrene (equivalent to approximately 2.34 equivalents when ACAPFP is set to 1 equivalent), 0.0055 g of azobisisobutyronitrile as a polymerization initiator, and 1.6205 g of cyclopentanone as a solvent. Except for preparing copolymer A19 using monomer composition A19 instead of monomer composition A1, various operations, measurements, and evaluations were carried out according to the operation of Example 1. The results are disclosed in Table 1 and Table 2.

(Preparation Example 1)

〈Preparation of copolymer〉

Add α-chloroacrylic acid-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl (ACAFPh) as monomer (d) to a glass ampoule with a stirrer inserted. 3.0000 g, monomer composition B1 of 1.0659 g of α-methylstyrene as monomer (e) and 1.8000 g of ion-exchange water as solvent and sealed. Repeat 10 times to pressurize and release nitrogen to remove the system. of oxygen.

Next, the system was heated to 60° C. and the reaction was carried out for 8 hours to obtain a reaction solution in which the crude polymerization product was suspended. Afterwards, the crude polymerization product in the reaction solution is recovered by filtration.

Next, the crude polymerization product recovered by filtration was dissolved in 10 g of THF, and the obtained solution was dropped into 100 g of a mixed solvent of THF and MeOH (THF: MeOH (mass ratio) 33:67) to form a white aggregate. Precipitate. The aggregate was recovered by filtration again, and the crude polymerization product recovered by filtration was dissolved in 10 g of THF, and the obtained solution was dropped into 100 g of a mixed solvent of THF and MeOH (THF: MeOH (mass ratio) 33:67 ), causing white aggregates (copolymer B1) to precipitate. Thereafter, the solution containing the precipitated copolymer B1 was filtered through a Kiriyama funnel to obtain white copolymer B1. The ¹ H-NMR method was used to calculate the proportion of monomer units in the obtained copolymer B1. The result was that the copolymer B1 contained 55 mol% of α-chloroacrylic acid-1-phenyl-1-trifluoromethyl-2,2 , a copolymer of 2-trifluoroethyl ester units and 45 mol% α-methylstyrene units.

Thereafter, the number average molecular weight, weight average molecular weight, molecular weight distribution and surface free energy of the obtained copolymer B1 were measured. The results are revealed in Table 1.

(Preparation Example 2)

In addition to the preparation of the copolymer, 2.3855 g of α-chloroacrylic acid-1-phenyl-2,2,2-trifluoroethyl (ACAHFPh) as monomer (d) and monomer (e) were used. Various operations and measurements were performed as in Preparation Example 1, except that copolymer B2 was prepared by replacing monomer composition B1 with monomer composition B2 of 1.0659 g of α-methylstyrene and 1.8000 g of ion-exchange water as a solvent. The results are revealed in Table 1.

(Example 15)

〈Preparation of positive photoresist composition〉

Copolymer A1 prepared as described above and copolymer B1 prepared as described above were dissolved in acetic acid as a solvent so that the mass ratio of copolymer A1 to copolymer B1 became 5:95 (copolymer A: copolymer B). Isoamyl ester was used to prepare a positive photoresist composition with a concentration of 2% by mass.

For the obtained positive photoresist composition, the γ value, Eth, pattern collapse resistance and photoresist residue are measured or evaluated. The results are revealed in Table 3.

(Example 16)

In addition to changing the mass ratio of copolymer A1 to copolymer B1 to 10:90 (copolymer A: copolymer B) in the preparation of the positive photoresist composition, various operations, measurements, and Evaluation. The results are revealed in Table 3.

(Example 17)

In addition to changing the mass ratio of copolymer A1 to copolymer B1 to 20:80 (copolymer A: copolymer B) in the preparation of the positive photoresist composition, various operations, measurements, and Evaluation. The results are revealed in Table 3.

(Example 18)

In addition to changing the mass ratio of copolymer A1 to copolymer B1 to 30:70 (copolymer A: copolymer B) in the preparation of the positive photoresist composition, various operations, measurements, and Evaluation. The results are revealed in Table 3.

(Example 19)

Except that copolymer A2 was used instead of copolymer A1 in the preparation of the positive photoresist composition, various operations, measurements, and evaluations were performed as in Example 17. The results are revealed in Table 3.

(Example 20)

Except that copolymer A5 was used instead of copolymer A1 in the preparation of the positive photoresist composition, various operations, measurements, and evaluations were performed as in Example 17. The results are revealed in Table 3.

(Example 21)

Except that copolymer A10 was used instead of copolymer A1 in the preparation of the positive photoresist composition, various operations, measurements, and evaluations were performed as in Example 17. The results are revealed in Table 3.

(Example 22)

Except that copolymer A11 was used instead of copolymer A1 in the preparation of the positive photoresist composition, various operations, measurements, and evaluations were performed as in Example 17. The results are revealed in Table 3.

(Example 23)

Except that copolymer A13 was used instead of copolymer A1 in the preparation of the positive photoresist composition, various operations, measurements, and evaluations were performed as in Example 17. The results are revealed in Table 3.

(Example 24)

Except that copolymer A14 was used instead of copolymer A1 in the preparation of the positive photoresist composition, various operations, measurements, and evaluations were performed as in Example 17. The results are revealed in Table 3.

(Example 25)

Except that copolymer B2 was used instead of copolymer B1 in the preparation of the positive photoresist composition, various operations, measurements, and evaluations were performed as in Example 17. The results are revealed in Table 3.

In addition, in the table, The so-called "solution" means solution polymerization, The so-called "overall" refers to the overall aggregation, The so-called "suspension" means suspension polymerization. "ACAFPh" means α-chloroacrylic acid-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl ester, "ACAHFPh" means α-chloroacrylic acid-1-phenyl-2,2,2-trifluoroethyl ester, "ACANFP" means α-chloroacrylic acid-2,2,3,3,4,4,5,5,5-nonafluoropentyl, "ACAHFB" means α-chloroacrylate-2,2,3,3,4,4,4-heptafluorobutyl, "ACAPFP" means alpha-chloroacrylate-2,2,3,3,3-pentafluoropropyl, "ACATFE" means α-chloroacrylate-2,2,2-trifluoroethyl, "IPA" means isopropyl alcohol.

"Table 1" Preparation example 2 B2 levitate 2.3855 1.0659 - 1.8000 8 60 55 45 132095 198274 1.501 34.1 1 B1 levitate 3.0000 1.0659 - 1.8000 8 60 55 45 123481 184728 1.496 31.0 Comparative example 5 A19 solution 3.0000 3.4764 0.0055 1.6205 6 78 50 50 25718 43834 1.704 - 4 A18 solution 3.0000 0.6506 0.1980 8.9801 6 78 80 20 8952 12601 1.408 - 3 A17 solution 3.0000 0.5389 0.1980 8.9801 6 78 80 20 9981 13928 1.395 - 2 A16 Overall 3.0000 2.4930 0.0040 6 78 50 50 27454 48923 1.782 - 1 A15 solution 3.0000 0.0396 7.0924 6 78 100 27082 47118 1.740 - Example 14 A14 solution 1.4442 2.3990 3.0000 0.0066 1.6556 6 78 20 30 50 28158 45004 1.598 21.7 13 A13 solution 0.7221 2.9394 3.0000 0.0067 1.6587 6 78 10 40 50 28168 44424 1.577 20.4 12 A12 solution 0.5731 1.6361 3.0000 0.0048 1.3781 6 78 10 40 50 32329 52341 1.619 - 11 A11 solution 0.5731 2.0711 3.0000 0.0048 1.4122 6 78 10 40 50 31204 50021 1.603 26.7 10 A10 solution 0.5731 2.5004 3.0000 0.0048 1.5196 6 78 10 40 50 31032 50123 1.615 25.4 9 A9 solution 0.7207 1.6361 3.0000 0.0048 1.4021 6 78 10 40 50 31203 54952 1.761 - 8 A8 solution 2.8826 0.5178 3.0000 0.0048 1.6013 6 78 40 10 50 28928 50722 1.753 - 7 A7 solution 2.1620 1.0356 3.0000 0.0048 1.5506 6 78 30 20 50 29831 52096 1.746 - 6 A6 solution 1.4413 1.5534 3.0000 0.0048 1.4999 6 78 20 30 50 29118 50471 1.733 - 5 A5 solution 0.7207 2.0711 3.0000 0.0048 1.4491 6 78 10 40 50 30129 53546 1.777 26.1 4 A4 solution 2.8826 0.6251 3.0000 0.0048 1.6281 6 78 40 10 50 26298 46111 1.753 - 3 A3 solution 2.1620 1.2502 3.0000 0.0048 1.6042 6 78 30 20 50 30208 47360 1.568 - 2 A2 solution 1.4413 1.8753 3.0000 0.0048 1.5803 6 78 20 30 50 26471 45883 1.733 24.9 1 A1 solution 0.7207 2.5004 3.0000 0.0048 1.5565 6 78 10 40 50 30434 48678 1.599 22.9 ellipses for copolymers aggregation method ACAFPh ACAHFPh ACANFP ACAHFB ACAPFP ACATFE alpha-methylstyrene ACAFPh ACAHFPh alpha-methylstyrene Azobisisobutyronitrile[g] Cyclopentanone[g] Ion exchange water[g] time[h] Temperature[℃] ACAFPh ACAHFPh ACANFP ACAHFB ACAPFP ACATFE alpha-methylstyrene ACAFPh ACAHFPh alpha-methylstyrene Number average molecular weight (Mn)[‐] Weight average molecular weight (Mw)[‐] Molecular weight distribution (Mw/Mn)[‐] Surface free energy [mJ/m ² ] Monomer(a) Monomer(b) Monomer(c) Monomer(d) Monomer(e) Single unit (I) Monomeric unit(II) Monomeric unit(III) Monomeric unit (IV) Single unit(V) Monomer usage [g] starter solvent reaction conditions Composition of copolymer [mol%] Physical properties of copolymers

"Table 2" Positive photoresist composition photoresist film Types of copolymers Types of developer Measurement and evaluation Eth [μC/cm ² ] γ value[-] Resistance to pattern collapse Photoresist residue Example 1 A1 IPA 99.40 15.05 A A 2 A2 IPA 90.55 11.05 A A 3 A3 IPA 68.96 11.55 A A 4 A4 IPA 78.05 10.93 A A 5 A5 IPA 88.65 13.43 A A 6 A6 IPA 84.54 10.78 A A 7 A7 IPA 65.68 11.12 A A 8 A8 IPA 76.54 10.32 A A 9 A9 IPA 110.54 12.12 A A 10 A10 IPA 102.30 12.43 A A 11 A11 IPA 103.12 12.21 A A 12 A12 IPA 116.54 11.89 A A 13 A13 IPA 99.31 15.00 A A 14 A14 IPA 90.57 10.89 A A Comparative example 1 A15 IPA 256.87 11.79 C A 2 A16 IPA 81.45 8.32 B A 3 A17 IPA 97.65 10.67 C B 4 A18 IPA 101.43 10.98 C B 5 A19 IPA 156.15 7.47 B C

"table 3" Positive photoresist composition photoresist film Type of copolymer A Type of copolymer B Copolymer A: Copolymer B (mass ratio) The difference between the surface free energy of copolymer B and the surface free energy of copolymer A [mJ/m ² ] Types of developer Measurement and evaluation Eth [μC/cm ² ] γ value[-] Resistance to pattern collapse Photoresist residue Example 15 A1 B1 5:95 8.1 IPA 80.01 15.98 A A 16 A1 B1 10:90 8.1 IPA 80.12 16.56 A A 17 A1 B1 20:80 8.1 IPA 81.56 18.34 A A 18 A1 B1 30:70 8.1 IPA 87.54 19.21 B A 19 A2 B1 20:80 6.1 IPA 80.00 11.60 A B 20 A5 B1 20:80 4.9 IPA 79.11 17.79 A A twenty one A10 B1 20:80 5.6 IPA 81.98 16.98 A A twenty two A11 B1 20:80 4.3 IPA 82.45 16.65 A A twenty three A13 B1 20:80 10.6 IPA 81.48 18.29 A A twenty four A14 B1 20:80 9.3 IPA 80.02 11.44 A A 25 A1 B2 20:80 11.2 IPA 84.31 17.65 A A

It is obvious from Table 2 and Table 3 that Examples 1 to 25 have high pattern collapse resistance (γ value is 10 or more) while ensuring the clarity of the photoresist pattern.

According to the present invention, a copolymer capable of improving pattern collapse resistance while ensuring the clarity of a photoresist pattern can be provided.

Furthermore, according to the present invention, it is possible to provide a copolymer mixture that can improve the pattern collapse resistance while ensuring the clarity of the photoresist pattern.

Furthermore, according to the present invention, it is possible to provide a positive photoresist composition capable of forming a photoresist pattern with high resistance to pattern collapse while ensuring clarity.

without

without.

without.

Claims (8)

A copolymer having: the following formula (I): 『Chemical 1』 [In the formula (I), L ¹ is a divalent linking group having a fluorine atom, Ar ¹ is an aromatic ring group which may have a substituent, and X ¹ is a halogen atom, a cyano group, an alkylsulfonyl group, or an alkoxy group. The monomer unit (I) represented by a group, a nitro group, a acyl group, an alkyl ester group or a halogenated alkyl group, which is different from the aforementioned monomer unit (I), is represented by the following formula (II): "Chemical 2" [In the formula (II ⁾ , R ¹ is an organic group with the number of fluorine atoms being 3 or more and 10 or less, and Monomer unit (II) represented by ester group or halogenated alkyl group, and the following formula (III): "Chemical 3" [In formula (III), R ² is an alkyl group, R ³ is a hydrogen atom, a fluorine atom, an unsubstituted alkyl group or an alkyl group substituted with a fluorine atom, and R ⁴ is a hydrogen atom, an unsubstituted alkyl group or an alkyl group substituted with a fluorine atom. Atom-substituted alkyl group, p and q are integers from 0 to 5, monomer unit (III) represented by p+q=5]. The copolymer according to claim 1, wherein the number of fluorine atoms in ^R1 is 5 or more. The copolymer according to claim 1, wherein the number of fluorine atoms in L ¹ is 4 or more. The copolymer as claimed in any one of claims 1 to 3, wherein the total ratio of the aforementioned monomer units (I) and the aforementioned monomer units (II) is set to 100 mol of all monomer units in the aforementioned copolymer. %, it is 45 mol% or more and 70 mol% or less. A copolymer mixture comprising copolymer A and copolymer B, wherein the aforementioned copolymer A is the copolymer as described in any one of claims 1 to 4, and the surface free energy of the aforementioned copolymer B is the same as that of the aforementioned copolymer A. The difference in surface free energy is more than 3 mJ/m ² . A copolymer mixture comprising copolymer A and copolymer B, wherein the aforementioned copolymer A is the copolymer described in any one of claims 1 to 4, and the aforementioned copolymer B has the following formula (IV): "Chemical 4" [In the formula (IV), L ² is a divalent linking group having a fluorine atom, Ar ² is an aromatic ring group which may have a substituent, and X ³ is a halogen atom, a cyano group, an alkylsulfonyl group, or an alkoxy group. group, nitro group, acyl group, alkyl ester group or halogenated alkyl group], and the following formula (V): "Chemical 5" [In the formula (V), R ⁵ is an alkyl group, R ⁶ is a hydrogen atom, an alkyl group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a carboxyl group or a halogenated carboxyl group, and R ⁷ is a hydrogen atom, an unsubstituted alkyl group or a fluorinated alkyl group. Atom-substituted alkyl group, r and s are integers from 0 to 5, and r+s=5] represents the monomer unit (V). A positive photoresist composition comprising any one of the following (A) to (C) and a solvent: (A) the copolymer described in any one of claims 1 to 4; (B) a copolymer material mixture, which includes copolymer A and copolymer B, wherein the aforementioned copolymer A is the copolymer according to any one of claims 1 to 4, and the surface free energy of the aforementioned copolymer B is the same as the surface free energy of the aforementioned copolymer A. The difference in free energy is 3 mJ/m ² or more; (C) a copolymer mixture including copolymer A and copolymer B, wherein the aforementioned copolymer A is a copolymer as described in any one of claims 1 to 4 The aforementioned copolymer B has the following formula (IV): 『Chemical 6』 [In the formula (IV), L ² is a divalent linking group having a fluorine atom, Ar ² is an aromatic ring group which may have a substituent, and X ³ is a halogen atom, a cyano group, an alkylsulfonyl group, or an alkoxy group. group, nitro group, acyl group, alkyl ester group or halogenated alkyl group], and the following formula (V): "Chemical 7" [In the formula (V), R ⁵ is an alkyl group, R ⁶ is a hydrogen atom, an alkyl group, a halogen atom, a halogenated alkyl group, a hydroxyl group, a carboxyl group or a halogenated carboxyl group, and R ⁷ is a hydrogen atom, an unsubstituted alkyl group or a fluorinated alkyl group. Atom-substituted alkyl group, r and s are integers from 0 to 5, and r+s=5] represents the monomer unit (V). The positive photoresist composition described in claim 7 does not contain components with a weight average molecular weight less than 1,000.