Positive-type resist composition

Abstract

A purpose of the present invention is to provide a positive-type resist composition that is capable of forming a highly distinct resist pattern at high sensitivity. The positive-type resist composition of the present invention includes a polymer A and a compound B. The polymer A is a main-chain scission polymer, the compound B is represented by formula (I), and when the content of the polymer A is WA and the content of the compound B is WB, the relationship WA ≥ WB is satisfied. Note that in formula (I), two or more of R1 to R3 may be bonded to form a ring structure which may have a substituent, and those of R1 to R3 that do not form a ring structure are each independently a hydrogen atom, a halogen atom, or an organic group, and may be the same or different.

Description

Positive-type resist composition

[0001] This invention relates to a positive-type resist composition.

[0002] Conventionally, in fields such as semiconductor manufacturing, polymers whose main chains are cleaved by irradiation with ionizing radiation such as electron beams or short-wavelength light such as ultraviolet light (including extreme ultraviolet (EUV)) (hereinafter, ionizing radiation and short-wavelength light may be collectively referred to as "ionizing radiation, etc.") and whose solubility in developing solutions increases have been used as main-chain cleavage type positive resists.

[0003] Such polymers are used, for example, as a positive-type resist composition containing the polymer and a solvent to form resist patterns. Specifically, a positive-type resist film (hereinafter sometimes simply referred to as "resist film") is formed by removing the solvent from the positive-type resist composition supplied to a substrate, and a desired pattern is drawn by irradiating (exposing) the resist film with ionizing radiation or the like. Next, by contacting (developing) the exposed resist film with a developer solution, the exposed parts of the resist film are dissolved, and a resist pattern consisting of unexposed parts can be formed on the substrate. Conventionally, improvements have been made to positive-type resist compositions that can be used to form main-chain-breaking positive-type resists in order to improve the characteristics of the resist pattern.

[0004] For example, Patent Document 1 states that the difference in surface free energy between them is 4 mJ / m ２ A positive-type resist composition comprising copolymer A and copolymer B, and a solvent is disclosed. According to Patent Document 1, using this positive-type resist composition makes it possible to form a resist pattern with less wear on the top of the resist pattern and high contrast. Patent Document 2 discloses a resist composition comprising a crosslinking agent that reacts with ionizing radiation or non-ionizing radiation with a wavelength of 300 nm or less, a solvent, and a polymer. According to Patent Document 1, using this resist composition makes it possible to form a clear resist pattern with a wide exposure margin and few defects.

[0005] International Publication No. 2022 / 190714, International Publication No. 2023 / 189969

[0006] However, there was room for improvement in the above conventional resist composition in terms of further improving the sensitivity in the resist pattern. In addition, it has been desired to further enhance the clarity of the resist pattern formed using the above conventional resist composition.

[0007] Therefore, an object of the present invention is to provide a positive resist composition capable of forming a resist pattern with high clarity at high sensitivity.

[0008] The present inventor conducted intensive studies to achieve the above object. And the present inventor newly found that a positive resist composition containing a main-chain cleavage type polymer and a compound represented by a predetermined formula in a predetermined quantitative ratio can form a resist pattern with high clarity at high sensitivity, and completed the present invention.

[0009] That is, the object of this invention is to advantageously solve the above problems, and according to the present invention, the positive resist compositions of the following [1] to [5] are provided.

[0010] [1] A positive resist composition containing a polymer A and a compound B, wherein the polymer A is a main-chain cleavage type polymer, and the compound B is represented by the following formula (I): (In formula (I), two or more of R １ to R ３ may be bonded to form a ring structure which may have a substituent, and R １ to R ３ which do not form a ring structure are each independently a hydrogen atom, a halogen atom, or an organic group, and may be the same or different from each other.) represented, and the content of the polymer A is W Ａ , the content of the compound B is W Ｂ , and W Ａ ≧ W ＢA positive-type resist composition that satisfies the following conditions. In this invention, "main-chain severing polymer" means a polymer whose main chain is severed and reduced in molecular weight by irradiation with ionizing radiation such as electron beams or short-wavelength light such as ultraviolet light (including extreme ultraviolet (EUV)). In this invention, "may have substituents" means "unsubstituted or substituted".

[0011] [2] R １ ~R ３ The positive-type resist composition according to [1] above, wherein two or more of the members are bonded together to form a ring structure which may have substituents.

[0012] [3] Compound B is of the following formulas (II) to (V): [In formula (II), R ４ ~R ８ Each of these independently comprises a hydrogen atom, a halogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, a nitro group, a cyano group, an optionally substituted ketone group, an optionally substituted aryl group, and NR ａ R ｂ (R ａ ~R ｂ Each is independently a hydrogen atom or an alkyl group, and may be the same or different from each other. Selected from the group consisting of ), which may be the same or different from each other, in formula (III), R ９ ~R １４ Each of these independently comprises a hydrogen atom, a halogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, a nitro group, a cyano group, an optionally substituted ketone group, an optionally substituted aryl group, and NR ａ R ｂ (R ａ ~R ｂ Each of these is independently a hydrogen atom or an alkyl group, and may be the same or different from each other. Selected from the group consisting of ), which may be the same or different from each other, in formula (IV), R １５ ~R １９Each of these independently comprises a hydrogen atom, a halogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, a nitro group, a cyano group, an optionally substituted ketone group, an optionally substituted aryl group, and NR ａ R ｂ (R ａ ~R ｂ Each is independently a hydrogen atom or an alkyl group, and may be the same or different from each other. Selected from the group consisting of ), which may be the same or different from each other, where L is a single bond or a divalent linking group, R ２０ ~R ２１ Each of these independently comprises a halogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, a nitro group, a cyano group, an optionally substituted ketone group, an optionally substituted aryl group, and NR ａ R ｂ (R ａ ~R ｂ Each of these is independently a hydrogen atom or an alkyl group, and they may be the same or different from each other.) are selected from the group consisting of ), and they may be the same or different from each other, and p is an integer between 0 and 4, and when p is 2 or more there are p R ２０ The elements may be identical or different from each other, q is an integer between 0 and 4 (inclusive), and when q is 2 or greater, there are q elements R. ２１ The positive-type resist composition described in [1] or [2] above, which is represented by either of the following:

[0013] [4] The positive resist composition according to any one of [1] to [3] above, wherein the content of compound B is 5 parts by mass or more and 50 parts by mass or less per 100 parts by mass of polymer A.

[0014] [5] The positive-type resist composition according to any one of [1] to [4] above, wherein the molecular weight of compound B is 2000 or less.

[0015] According to the present invention, it is possible to provide a positive-type resist composition that can form highly clear resist patterns with high sensitivity.

[0016] Embodiments of the present invention will now be described in detail. Herein, the positive-type resist composition of the present invention is used to form a resist film when forming a resist pattern using electron beams, EUV or other ionizing radiation. The resist pattern formation method of the present invention forms a resist pattern using the positive-type resist composition of the present invention. Each component disclosed herein, as well as preferred embodiments, numerical ranges, and thresholds defining such numerical ranges, can be independently combined with each other in any manner.

[0017] (Positive-type resist composition) The positive-type resist composition of the present invention comprises polymer A and compound B, and optionally further contains a solvent and other components. Here, in the positive-type resist composition of the present invention, polymer A is a main-chain cleavage type polymer, and compound B is of the following formula (I): [In formula (I), R １ ~R ３ Two or more of these may be bonded together to form a ring structure which may have substituents, and R may not form a ring structure １ ~R ３ Each of these is independently a hydrogen atom, a halogen atom, or an organic group, and may be the same or different from each other. The content of polymer A is expressed as W Ａ The content of compound B is set to W Ｂ When that happens, W Ａ ≧W Ｂ It is characterized by satisfying the following conditions.

[0018] Furthermore, the positive-type resist composition of the present invention comprises a main-chain cleavage polymer A and a compound B represented by the above formula (I), wherein the content of polymer A is W Ａ The content of compound B is W Ｂ When W Ａ ≧W Ｂ To satisfy this condition, the positive-type resist composition can be used to form highly clear resist patterns with high sensitivity. The reason why the above effects are obtained by using the positive-type resist composition of the present invention is not entirely clear, but it is presumed to be as follows.

[0019] First, since the positive-type resist composition of the present invention contains a main-chain cleavage type polymer A, when a resist film formed using the positive-type resist composition of the present invention is exposed by irradiating it with ionizing radiation or the like, the main chain of polymer A in the resist film is cleaved, and a double bond or radical may be generated at the cleavage end of the main chain. Here, the positive-type resist composition of the present invention has an N-oxide structure (N) represented by the above formula (I). ＋ -O － The present invention contains compound B having ), and upon exposure, the double bonds or radicals at the main chain ends of polymer A react with compound B, and compound B can be added to the cleaved ends of the main chain. This addition of compound B increases the polarity of the resist film and improves the solubility of the resist film in the developer. As a result, it is believed that a highly clear resist pattern can be formed with high sensitivity by using the positive-type resist composition of the present invention. Furthermore, the positive-type resist composition of the present invention has a polymer A content of W Ａ The content of compound B is W Ｂ When that happens, W Ａ ≧W Ｂ It is believed that the above effects can be achieved effectively by satisfying these conditions. For the reasons stated above, it is believed that a highly clear resist pattern can be formed with high sensitivity using the positive-type resist composition of the present invention.

[0020] The positive-type resist composition of the present invention has a polymer A content of W Ａ The content of compound B is W Ｂ When that happens, W Ａ ≧W ＢThe following conditions must be met: The content of compound B in the positive-type resist composition of the present invention must be 100 parts by mass or less per 100 parts by mass of polymer A. If the content of compound B in the positive-type resist composition exceeds 100 parts by mass per 100 parts by mass of polymer A, sufficient sensitivity in resist pattern formation cannot be ensured, and the clarity of the formed resist pattern decreases. The content of compound B in the positive-type resist composition of the present invention is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, preferably 50 parts by mass or less, more preferably 40 parts by mass or less, even more preferably 30 parts by mass or less, even more preferably 25 parts by mass or less, and particularly preferably 20 parts by mass or less, per 100 parts by mass of polymer A. If the content of compound B per 100 parts by mass of polymer A is within the above range, the sensitivity in resist pattern formation can be further improved, and the clarity of the resist pattern can be further enhanced.

[0021] <Polymer A> As polymer A, a main-chain cleavage type positive resist can be used, in which the main chain is cleaved and reduced in molecular weight by irradiation with ionizing radiation such as electron beams or short-wavelength light such as ultraviolet light (including extreme ultraviolet (EUV)). Such polymer A is not particularly limited, and for example, those described in Japanese Patent Publication No. 8-3636, Japanese Patent Application Publication No. 2020-134683, International Publication No. 2019 / 150966, and International Publication No. 2020 / 066806 can be used.

[0022] In particular, from the viewpoint of further improving the sensitivity in resist pattern formation and further enhancing the clarity of the resist pattern, polymer A is given the following formula (VI): [In formula (VI), R ２２ is a halogen atom or an alkyl group substituted with a halogen atom, R ２３ R is an organic group, ２４ and R ２５Each of these is independently a hydrogen atom, a fluorine atom, an unsubstituted alkyl group, or an alkyl group substituted with a fluorine atom, and may be the same or different from each other. A monomer unit (VI) represented by ] and the following formula (VII): [In formula (VII), R ２６ , R ２９ and R ３０ Each of these is independently a hydrogen atom, a halogen atom, an unsubstituted alkyl group, or an alkyl group substituted with a halogen atom, and they may be the same or different from each other, R ２７ R is a hydrogen atom, a fluorine atom, an unsubstituted alkyl group, or an alkyl group substituted with a fluorine atom. ２８ It is preferable to use a polymer having monomer units (VII) represented by ], where is a hydrogen atom, an unsubstituted alkyl group, or an alkyl group substituted with a fluorine atom, and m and n are integers between 0 and 5, with m + n = 5.

[0023] Polymer A having monomer units (VI) and monomer units (VII) as described above may contain monomer units other than monomer units (VI) and monomer units (VII), but the proportion of monomer units (VI) and monomer units (VII) in the total monomer units constituting polymer A is preferably 90 mol% or more, more preferably 99 mol%, and even more preferably 100 mol% (i.e., polymer A contains only monomer units (VI) and monomer units (VII)). In this invention, the proportion of each monomer unit in the total monomer units constituting polymer A can be measured using nuclear magnetic resonance (NMR) spectroscopy, and more specifically, it can be measured according to the method described in the examples of this specification.

[0024] Furthermore, polymer A having monomer units (VI) and monomer units (VII) as described above may be any of the following, as long as it has monomer units (VI) and monomer units (VII), for example, a random polymer, a block polymer, an alternating polymer, etc., but it is preferable that the polymer contains 90% by mass or more (up to 100% by mass) of the alternating polymer.

[0025] Furthermore, since polymer A, as described above, contains predetermined monomer units (VI) and (VII), when irradiated with ionizing radiation or the like, the main chain is cleaved and its molecular weight is reduced.

[0026] <<Monomeric Unit (VI)>> The monomer unit (VI) is given by the following formula (VI'): [In formula (VI'), R ２２ ~R ２５ This is the same as formula (VI). It is a structural unit derived from monomer (a) represented by ]. In this invention, "monomer unit derived from monomer" means "a repeating unit derived from the monomer contained in a polymer obtained using the monomer."

[0027] Furthermore, the proportion of monomer units (VI) in the total monomer units constituting polymer A is not particularly limited, but can be, for example, 30 mol% or more and 70 mol% or less, and preferably 40 mol% or more and 60 mol% or less.

[0028] Here, R in equation (VI) ２２ From the viewpoint of absorption efficiency of ionizing radiation, etc., it is necessary that the element be a halogen atom or an alkyl group substituted with a halogen atom.

[0029] R in equation (VI) ２２ Examples of halogen atoms that can constitute this include fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).

[0030] R in equation (VI) ２２ Examples of alkyl groups substituted with halogen atoms that can constitute this include groups having a structure in which some or all of the hydrogen atoms in an alkyl group having 1 to 5 carbon atoms are replaced with halogen atoms.

[0031] Among the above, from the viewpoint of improving the cleavage of the main chain of polymer A when irradiated with ionizing radiation, etc., R in formula (VI) ２２R is preferably a chlorine atom, a fluorine atom, or an alkyl group having 1 to 5 carbon atoms substituted with a fluorine atom, more preferably a chlorine atom, a fluorine atom, or a perfluoromethyl group, even more preferably a chlorine atom or a fluorine atom, and particularly preferably a chlorine atom. Note that R in formula (VI') ２２ Monomers in which R is a chlorine atom exhibit excellent polymerization properties, and in formula (VI) ２２ Polymers having monomer units (VI) in which the monomer is a chlorine atom are also advantageous in that they are easy to prepare.

[0032] R in equation (VI) ２４ ~R ２５ The unsubstituted alkyl groups that can constitute the compound are not particularly limited, but include unsubstituted alkyl groups having 1 to 5 carbon atoms.

[0033] R in equation (VI) ２４ ~R ２５ Examples of alkyl groups substituted with fluorine atoms that can constitute this include, without any particular limitations, groups having a structure in which some or all of the hydrogen atoms in an alkyl group having 1 to 5 carbon atoms are replaced with fluorine atoms.

[0034] Among the above, from the viewpoint of improving the ease of preparation of polymer A, R in formula (VI) ２４ ~R ２５ Each of these is preferably a hydrogen atom or an unsubstituted alkyl group, more preferably a hydrogen atom or an unsubstituted alkyl group having 1 to 5 carbon atoms, and even more preferably a hydrogen atom.

[0035] R in equation (VI) ２３ The organic groups that can constitute this include, but are not particularly limited, alkyl groups having 1 to 10 carbon atoms that may have substituents, alkenyl groups having 2 to 10 carbon atoms that may have substituents, alkynyl groups having 2 to 10 carbon atoms that may have substituents, aliphatic groups having 2 to 10 carbon atoms that may have substituents, etc.; aromatic hydrocarbon groups having 6 to 12 carbon atoms that may have substituents; aromatic heterocyclic groups having 1 to 12 carbon atoms that may have substituents; and the like.

[0036] The substituents are not particularly limited, and examples thereof include a halogen atom (e.g., a fluorine atom), a hydroxyl group, a carboxyl group, an amino group, a cyano group, a sulfonyl group, an amide group, an ester group, an organometallic group, and the like. Among them, from the viewpoint of ensuring good cleavage property of the main chain of the polymer when irradiated with ionizing radiation or the like, a halogen atom is preferable, and a fluorine atom is more preferable.

[0037] Here, R in formula (VI) ２３ is ２ -Ar [where L ２ is a divalent linking group having a single bond or a halogen atom, and Ar is an aromatic ring group which may have a substituent. ] It is preferably a group represented by. When R ２３ is a group represented by L ２ -Ar, the sensitivity in resist pattern formation can be further improved, and the clarity of the resist pattern can be further enhanced.

[0038] And L ２ is preferably a divalent linking group having a halogen atom. As the halogen atom that L ２ may have, a fluorine atom is preferable, and as the divalent linking group of L ２ an alkylene group having 1 to 5 carbon atoms is preferable, and a methylene group is more preferable. And as L ２ a divalent linking group having a fluorine atom is preferable, an alkylene group having 1 to 5 carbon atoms having a fluorine atom is more preferable, and a bis(trifluoromethyl)methylene group (-C(CF ３ ) ２ -) is more preferable.

[0039] The number of halogen atoms of L ２ is preferably 3 or more, more preferably 4 or more, still more preferably 5 or more, preferably 10 or less, and more preferably 7 or less. When the number of halogen atoms of L ２ is at least the above lower limit, the sensitivity in resist pattern formation can be further improved, and the clarity of the resist pattern can be further enhanced. On the other hand, L ２If the number of halogen atoms is below the above upper limit, the manufacturing efficiency of polymer A can be improved.

[0040] Also, L ２ Examples of optionally substituted aromatic ring groups that can constitute Ar in a group represented by -Ar include optionally substituted aromatic hydrocarbon ring groups and optionally substituted aromatic heterocyclic groups.

[0041] Furthermore, the aromatic hydrocarbon ring group is not particularly limited, but examples include benzene ring group (phenyl group), biphenyl ring group, naphthalene ring group, azulene ring group, anthracene ring group, phenanthrene ring group, pyrene ring group, chrysene ring group, naphthacene ring group, triphenylene ring group, o-terphenyl ring group, m-terphenyl ring group, p-terphenyl ring group, acenaphthene ring group, coronene ring group, fluorene ring group, fluoranthrene ring group, pentacene ring group, perylene ring group, pentaphene ring group, picene ring group, pyranthrene ring group, and the like.

[0042] Furthermore, aromatic heterocyclic groups are not particularly limited, but include, for example, furan rings, thiophene rings, pyridine rings, pyridazine rings, pyrimidine rings, pyrazine rings, triazine rings, oxadiazole rings, triazole rings, imidazole rings, pyrazole rings, thiazole rings, indole rings, benzimidazole rings, benzothiazole rings, benzoxazole rings, quinoxaline rings, quinazoline rings, phthalazine rings, benzofuran rings, dibenzofuran rings, benzothiophene rings, dibenzothiophene rings, and carbazole rings.

[0043] Furthermore, the substituents that Ar may have are not particularly limited, and include, for example, alkyl groups, fluorine atoms, fluoroalkyl groups, etc. Examples of alkyl groups as substituents that Ar may have include chain alkyl groups having 1 to 6 carbon atoms, such as methyl groups, ethyl groups, propyl groups, n-butyl groups, and isobutyl groups. Examples of fluoroalkyl groups as substituents that Ar may have include fluoroalkyl groups having 1 to 5 carbon atoms, such as trifluoromethyl groups, trifluoroethyl groups, and pentafluoropropyl groups.

[0044] In particular, Ar is preferably an aromatic hydrocarbon ring group which may have substituents, more preferably an unsubstituted aromatic hydrocarbon ring group, and even more preferably a benzene ring group (phenyl group).

[0045] And, L ２ -Ar can be, for example, a benzyl group (C ６ H ５ -CH ２ -) of -CH ２ Examples include structures in which at least one, preferably both, of the two hydrogen atoms of the benzyl group are substituted with a fluorine atom or a fluoroalkyl group having 1 to 5 carbon atoms. In particular, the benzyl group -CH ２ A structure in which the - is substituted with a perfluoroalkyl group having 1 to 5 carbon atoms is preferred, and the benzyl group -CH ２ A structure in which the - is substituted with a perfluoroalkyl group having 1 to 3 carbon atoms is more preferred, and the benzyl group -CH ２ A structure in which the negative sign is replaced with a trifluoromethyl group is even more preferred.

[0046] From the viewpoint of further improving sensitivity in resist pattern formation and further enhancing the clarity of the resist pattern, in formula (VI), R ２３ is L ２ It is preferably a group represented by -Ar, and in formula (VI), R ２２ is a chlorine atom, R ２４ and R ２５ is a hydrogen atom, R ２３ is L ２ It is more preferable that the group be represented by -Ar.

[0047] Furthermore, the monomer (a) represented by the above-mentioned formula (VI') that can form the monomer unit (VI) represented by the above-mentioned formula (VI) is not particularly limited, but examples include α-chloroacrylate-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl (ACAFPh; monomer represented by the following formula (a-1)), α-chloroacrylate-1-phenyl-1-pentafluoroethyl (monomer represented by the following formula (a-2)), and α-chloroacrylate-1-phenyl-1-di(2-trifluoroethyl)-1-fluoromethyl (monomer represented by the following formula (a-3)). Among these, it is preferable to use α-chloroacrylate-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl (ACAFPh).

[0048] <<Monomeric Unit (VII)>> The monomer unit (VII) is given by the following formula (VII'): [In formula (VII'), R ２６ ~R ３０ m and n are the same as in formula (VII). These are structural units derived from monomer (b) represented by ].

[0049] Furthermore, the proportion of monomer unit (VII) in the total monomer units constituting polymer A is not particularly limited, but can be, for example, 30 mol% or more and 70 mol% or less, and preferably 40 mol% or more and 60 mol% or less.

[0050] R in equation (VII) ２６ and R ２９ ~R ３０ Examples of halogen atoms that can constitute it include R in formula (VI). ２２ Examples include halogen atoms that can constitute it.

[0051] R in equation (VII) ２６ ~R ３０ Examples of unsubstituted alkyl groups that can constitute it include R in formula (VI). ２４ ~R ２５ Examples of unsubstituted alkyl groups that can constitute this include similar groups.

[0052] R in equation (VII) ２６ and R２９ ~R ３０ Examples of alkyl groups substituted with halogen atoms that can constitute it include, for example, R in formula (VI). ２２ Examples include alkyl groups substituted with halogen atoms that can constitute the group.

[0053] R in equation (VII) ２７ ~R ２８ Examples of alkyl groups substituted with fluorine atoms that can constitute it include, for example, R in formula (VI). ２４ ~R ２５ Examples include alkyl groups substituted with fluorine atoms that can constitute the group.

[0054] Among the above, from the viewpoint of improving the ease of preparation of polymer A, R in formula (VII) ２６ R is preferably a hydrogen atom or an unsubstituted alkyl group, more preferably a hydrogen atom or an unsubstituted alkyl group having 1 to 5 carbon atoms, even more preferably a hydrogen atom or a methyl group, and particularly preferably a methyl group. Also, from the viewpoint of improving the ease of preparation of polymer A, R in formula (VII) ２９ ~R ３０ Each of these is preferably a hydrogen atom or an unsubstituted alkyl group, more preferably a hydrogen atom or an unsubstituted alkyl group having 1 to 5 carbon atoms, even more preferably a hydrogen atom or a methyl group, and particularly preferably a hydrogen atom.

[0055] Multiple Rs exist in equation (VII) ２７ and / or R ２８ Preferably, all of them are hydrogen atoms, unsubstituted alkyl groups, or alkyl groups substituted with fluorine atoms; more preferably, they are hydrogen atoms, unsubstituted alkyl groups having 1 to 5 carbon atoms, or alkyl groups having 1 to 5 carbon atoms substituted with fluorine atoms; even more preferably, they are alkyl groups having 1 to 5 carbon atoms substituted with hydrogen atoms or fluorine atoms; and particularly preferably, they are hydrogen atoms or trifluoromethyl groups.

[0056] In equation (VII), m is 5, n is 0, and there are 5 R ２７Preferably, all of them are hydrogen atoms, unsubstituted alkyl groups, or alkyl groups substituted with fluorine atoms, and there are five R ２７ It is more preferable that all of them are hydrogen atoms, unsubstituted alkyl groups having 1 to 5 carbon atoms, or alkyl groups having 1 to 5 carbon atoms substituted with fluorine atoms, and there are five R ２７ It is more preferable that all of them are alkyl groups having 1 to 5 carbon atoms substituted with hydrogen atoms or fluorine atoms, and there are five R ２７ It is particularly preferable that all of them are hydrogen atoms or trifluoromethyl groups.

[0057] Furthermore, the monomer (b) represented by formula (VII') above, which can form the monomer unit (VII) represented by formula (VII) above, is not particularly limited and includes, for example, α-methylstyrene (AMS) and its derivatives such as the following monomers (b-1) to (b-19) (for example, 4-fluoro-α-methylstyrene (4FAMS) according to formula (b-2), and 3,5-bis(trifluoromethyl)-α-methylstyrene (BAMS) according to formula (b-7).

[0058] Furthermore, it is preferable that the monomer unit (VII) is a structural unit derived from the monomer (b-1) or monomer (b-7) described above.

[0059] <<Other Monomer Units>> Other monomer units are not particularly limited, but examples include monomer units derived from known monomers copolymerizable with monomers (a) and (b) described above. Polymer A may contain one or more of these other monomer units.

[0060] <<Method for preparing polymer A>> The method for preparing polymer A is not particularly limited. For example, polymer A, which contains the monomer units (VI) and (VII) described above, can be prepared by polymerizing a monomer composition containing the monomer (a) and monomer (b) described above, and then purifying the polymer obtained as desired.

[0061] [Polymerization of Monomer Composition] Here, the monomer composition used to prepare polymer A containing monomer units (VI) and (VII) described above can be a mixture of monomer components containing monomer (a) and monomer (b), an optional solvent, an optional polymerization initiator, and an optional additive. The polymerization of the monomer composition can be carried out using known methods. Among these, cyclopentanone, water, etc., are preferred as the solvent.

[0062] Furthermore, polymers obtained by polymerizing monomer compositions are not particularly limited and can be recovered by adding a good solvent such as tetrahydrofuran to a solution containing the polymer, and then dropping the solution containing the good solvent into a poor solvent such as methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, or hexane to coagulate the polymer.

[0063] [Purification of Polymers] The purification method used to purify the obtained polymers is not particularly limited and includes known purification methods such as reprecipitation and column chromatography. Among these, reprecipitation is preferred as the purification method. Furthermore, the purification of the polymers may be repeated multiple times.

[0064] Furthermore, the purification of polymers by reprecipitation is preferably carried out, for example, by dissolving the obtained polymer in a good solvent such as tetrahydrofuran, and then dropping the resulting solution into a mixed solvent of a good solvent such as tetrahydrofuran and a poor solvent such as methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, or hexane, thereby precipitating a portion of the polymer. By purifying the polymer by dropping the solution into a mixed solvent of a good solvent and a poor solvent in this way, the molecular weight distribution, number average molecular weight, and weight average molecular weight of the obtained polymer can be easily adjusted by changing the types and mixing ratios of the good and poor solvents. Specifically, for example, the higher the proportion of the good solvent in the mixed solvent, the higher the molecular weight of the polymer precipitated in the mixed solvent can be.

[0065] When purifying polymers by reprecipitation, polymer A may be polymer precipitated in a mixed solvent of a good solvent and a poor solvent, or polymer that did not precipitate in the mixed solvent (i.e., polymer dissolved in the mixed solvent), provided that the desired properties are met. Here, polymer that did not precipitate in the mixed solvent can be recovered from the mixed solvent using known methods such as concentration to dryness.

[0066] <Compound B> Compound B is given by the following formula (I): [In formula (I), R １ ~R ３ Two or more of these may be bonded together to form a ring structure which may have substituents, and R may not form a ring structure １ ~R ３ Each of these is independently a hydrogen atom, a halogen atom, or an organic group, and they may be the same or different from each other. The compound is represented by [ ].

[0067] R １ ~R ３ The ring structure formed by the bonding of two or more of these elements is not particularly limited and may be either a saturated ring or an unsaturated ring. Examples of saturated rings include monocyclic saturated hydrocarbon rings, monocyclic saturated heterocycles, polycyclic saturated hydrocarbon rings, and polycyclic saturated heterocycles. Examples of unsaturated rings include monocyclic unsaturated hydrocarbon rings, monocyclic unsaturated heterocycles, polycyclic unsaturated hydrocarbon rings, and polycyclic unsaturated heterocycles.

[0068] Among the above, from the viewpoint of further improving the sensitivity in resist pattern formation and further enhancing the clarity of the resist pattern, R １ ~R ３ The ring structure formed by the bonding of two or more of these elements is preferably a saturated ring, more preferably a monocyclic saturated ring, and even more preferably a monocyclic saturated heterocyclic ring.

[0069] Also, R １ ~R ３The number of ring members in the ring structure formed by the bonding of two or more of these is not particularly limited, but is usually 3 to 20, preferably 4 to 12, more preferably 6 to 12, and even more preferably 6.

[0070] These ring structures may have substituents. Substituents that the ring structures may have are not particularly limited, but include, for example, halogen atoms, hydroxyl groups, carboxyl groups, cyano groups, vinyl groups, alkoxy groups, alkyl groups, alkyl halides, nitro groups, ketone groups, aryl groups, and NR ａ R ｂ (R ａ ~R ｂ Each of these elements is independently a hydrogen atom or an alkyl group, and they may be the same or different from each other. ) are some examples.

[0071] R in equation (I) １ ~R ３ Examples of halogen atoms that can constitute this include fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).

[0072] R in equation (I) １ ~R ３ Organic groups that can constitute the compound include, but are not limited to, alkyl groups having 1 to 10 carbon atoms that may have substituents, alkenyl groups having 2 to 10 carbon atoms that may have substituents, alkynyl groups having 2 to 10 carbon atoms that may have substituents, aliphatic groups having 2 to 10 carbon atoms that may have substituents, etc.; aromatic hydrocarbon groups having 6 to 12 carbon atoms that may have substituents; aromatic heterocyclic groups having 1 to 12 carbon atoms that may have substituents; and others. Substituents include, but are not limited to, halogen atoms, hydroxyl groups, carboxyl groups, cyano groups, vinyl groups, alkoxy groups, alkyl groups, alkyl halides, nitro groups, ketone groups, aryl groups, NR ａ R ｂ (R ａ ~R ｂ Each of these elements is independently a hydrogen atom or an alkyl group, and they may be the same or different from each other. ) are some examples.

[0073] Here, from the viewpoint of further improving the sensitivity in resist pattern formation and further enhancing the clarity of the resist pattern, compound B is defined by the following formulas (II) to (V): [In formula (II), R ４ ~R ８ Each of these independently comprises a hydrogen atom, a halogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, a nitro group, a cyano group, an optionally substituted ketone group, an optionally substituted aryl group, and NR ａ R ｂ (R ａ ~R ｂ Each is independently a hydrogen atom or an alkyl group, and may be the same or different from each other. Selected from the group consisting of ), which may be the same or different from each other, in formula (III), R ９ ~R １４ Each of these independently comprises a hydrogen atom, a halogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, a nitro group, a cyano group, an optionally substituted ketone group, an optionally substituted aryl group, and NR ａ R ｂ (R ａ ~R ｂ Each of these is independently a hydrogen atom or an alkyl group, and may be the same or different from each other. Selected from the group consisting of ), which may be the same or different from each other, in formula (IV), R １５ ~R １９ Each of these independently comprises a hydrogen atom, a halogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, a nitro group, a cyano group, an optionally substituted ketone group, an optionally substituted aryl group, and NR ａ R ｂ (R ａ ~R ｂ Each is independently a hydrogen atom or an alkyl group, and may be the same or different from each other. Selected from the group consisting of ), which may be the same or different from each other, where L is a single bond or a divalent linking group, R ２０ ~R２１ Each of these independently comprises a halogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, a nitro group, a cyano group, an optionally substituted ketone group, an optionally substituted aryl group, and NR ａ R ｂ (R ａ ~R ｂ Each of these is independently a hydrogen atom or an alkyl group, and they may be the same or different from each other.) are selected from the group consisting of ), and they may be the same or different from each other, and p is an integer between 0 and 4, and when p is 2 or more there are p R ２０ The elements may be identical or different from each other, q is an integer between 0 and 4 (inclusive), and when q is 2 or greater, there are q elements R. ２１ These may be the same or different from each other. It is preferable that they be represented by either of the following:

[0074] R in equations (II) to (V) ４ ~R ２１ The alkyl group that may have substituents can be any alkyl group having 1 to 5 carbon atoms, without any particular limitations. Examples of substituents include halogen atoms, hydroxyl groups, carboxyl groups, amino groups, cyano groups, vinyl groups, and alkoxy groups.

[0075] R in equations (II) to (V) ４ ~R ２１ The alkoxy groups that may constitute the compound are not particularly limited to alkoxy groups having 1 to 5 carbon atoms that may have substituents. Examples of substituents include halogen atoms, hydroxyl groups, carboxyl groups, amino groups, cyano groups, vinyl groups, and the like.

[0076] R in equations (II) to (V) ４ ~R ２１ The ketone group that may have substituents and can constitute the compound is not particularly limited to groups represented by -CO-R (where R is an alkyl group having 1 to 5 carbon atoms). Examples of substituents include halogen atoms, hydroxyl groups, carboxyl groups, amino groups, cyano groups, vinyl groups, alkoxy groups, and alkyl halogenates.

[0077] R in equations (II) to (V) ４ ~R ２１ Examples of aryl groups that may have substituents and can constitute the compound include, but are not limited to, aryl groups with 6 to 10 carbon atoms, such as phenyl groups and naphthyl groups. Examples of substituents include halogen atoms, hydroxyl groups, carboxyl groups, amino groups, cyano groups, vinyl groups, alkoxy groups, and alkyl halides.

[0078] R in equations (II) to (V) ４ ~R ２１ NR that can constitute ａ R ｂ This does not particularly limit NR ａ R ｂ (R ａ ~R ｂ Examples include a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, which may be the same or different from each other.

[0079] Furthermore, in order to further improve the sensitivity in resist pattern formation and to further enhance the clarity of the resist pattern, R in equations (II) to (IV) ４ ~R １９ These are, respectively, a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, and NR ａ R ｂ (R ａ ~R ｂ It is preferably a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, which may be the same or different from each other), a halogen atom, or an aryl group, and is preferably a hydrogen atom, a methyl group, a methoxy group, or an amino group (NH ２ ), NHR (where R is an alkyl group having 1 to 5 carbon atoms), fluorine atom, chlorine atom, bromine atom, iodine atom, or phenyl group is more preferable, and hydrogen atom, methyl group, methoxy group, amino group (NH ２ It is even more preferable that it be ), or NHR (where R is an alkyl group having 1 to 5 carbon atoms).

[0080] Furthermore, in order to further improve the sensitivity in resist pattern formation and to further enhance the clarity of the resist pattern, R in formula (V) ２０ ~R ２１ These are methyl group, NR ａ R ｂ (R ａ ~R ｂ It is preferably a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, which may be the same or different from each other), a halogen atom, or an aryl group, and is preferably a methyl group, an amino group (NH ２ It is more preferable that the group is an ), NHR (where R is an alkyl group having 1 to 5 carbon atoms), or a phenyl group.

[0081] Examples of divalent linking groups constituting L in formula (V) include single bonds, ether bonds, optionally substituted alkylene groups, and optionally substituted arylene groups. Substituents are not particularly limited and include halogen atoms, hydroxyl groups, carboxyl groups, amino groups, cyano groups, vinyl groups, alkoxy groups, and alkyl halides. Among these, L is preferably a single bond.

[0082] In equation (V), p and q must be integers between 0 and 4, preferably between 0 and 3, more preferably between 0 and 2, even more preferably between 0 and 1, and particularly preferably p = 0 and q = 0.

[0083] Furthermore, from the viewpoint of further improving the sensitivity in resist pattern formation and further enhancing the clarity of the resist pattern, compound B is preferably represented by any of the above-mentioned formulas (II), (IV), and (V), and more preferably by formula (IV).

[0084] Examples of compound B represented by formulas (II) to (V) include the following compounds (c-1) to (c-15).

[0085] Among the compounds (c-1) to (c-15) described above, compounds (c-1) to (c-3), (c-5), (c-7) to (c-8), (c-10) to (c-11), and (c-14) to (c-15) are preferred from the viewpoint of further improving the sensitivity in resist pattern formation and further enhancing the clarity of the resist pattern, (c-1), (c-7), and (c-15) are more preferred, and (c-1) is even more preferred.

[0086] <<Properties of Compound B>> [Molecular Weight] The molecular weight of Compound B is preferably 2000 or less, more preferably 1000 or less, even more preferably 500 or less, even more preferably 250 or less, and particularly preferably 150 or less, from the viewpoint of further improving the sensitivity in resist pattern formation and further enhancing the clarity of the resist pattern. The lower limit of the molecular weight of Compound B is not particularly limited and can be, for example, 50 or more, or 80 or more.

[0087] [Mulliken charge] Compound B has N ＋ -O － Oxygen atom in bond (O － The Mullliken charge of the oxygen atom (O) is preferably -0.500 or less, more preferably -0.510 or less, even more preferably -0.530 or less, even more preferably -0.550 or less, and particularly preferably -0.570 or less. － If the Mulliken charge of the oxygen atom (O) is less than or equal to the above value, the oxidizing ability of compound B is sufficiently ensured, further improving the sensitivity in resist pattern formation and further enhancing the clarity of the resist pattern. － The lower limit of the Mulliken charge of the oxygen atom is not particularly limited and can be, for example, -0.800 or higher, -0.700 or higher, or -0.600 or higher. The Mulliken charge of the oxygen atom can be determined using the method described in the examples of this specification.

[0088] <Solvent> The solvent is not particularly limited as long as it is capable of dissolving or dispersing the polymer A and compound B described above, and known solvents such as the solvent described in Japanese Patent Publication No. 5938536 can be used. In particular, from the viewpoint of obtaining a positive-type resist composition with appropriate viscosity and improving the coating properties of the positive-type resist composition, anisole, propylene glycol monomethyl ether acetate (PGMEA), cyclopentanone, cyclohexanone, isoamyl acetate, 1-methoxy-2-propanol (PGME), and γ-butyllactone are preferred as solvents, propylene glycol monomethyl ether acetate (PGMEA), isoamyl acetate, and 1-methoxy-2-propanol (PGME) are more preferred, and propylene glycol monomethyl ether acetate (PGMEA) and 1-methoxy-2-propanol (PGME) are even more preferred. Note that one solvent may be used alone, or multiple solvents may be used in mixture form.

[0089] Here, if the positive-type resist composition of the present invention contains a solvent, the concentration of compound B in the positive-type resist composition is preferably 0.05% by mass or more, more preferably 0.10% by mass or more, even more preferably 0.15% by mass or more, preferably 0.50% by mass or less, more preferably 0.45% by mass or less, and even more preferably 0.40% by mass or less, based on 100% by mass of the total amount of the positive-type resist composition. If the concentration of compound B in the positive-type resist composition is equal to or greater than the above values, the sensitivity in resist pattern formation can be further improved, and the clarity of the resist pattern can be further enhanced. On the other hand, if the concentration of compound B in the positive-type resist composition is equal to or less than the above values, the solubility of compound B in the positive-type resist composition is sufficiently ensured, which further improves the sensitivity in resist pattern formation and enhances the clarity of the resist pattern.

[0090] <Other Components> In addition to the components described above, the positive-type resist composition of the present invention may optionally further contain polymer components other than polymer A described above and known additives that can be incorporated into the resist composition. The amount of additives is not particularly limited and can be added in appropriate amounts depending on the application.

[0091] <Method for preparing a positive-type resist composition> A positive-type resist composition can be prepared by mixing the polymer A and compound B described above, as well as any solvent and other components used. The mixing method is not particularly limited and can be done by any known method. Alternatively, the mixture may be prepared by filtering after mixing each component.

[0092] (Method for forming a resist pattern) A method for forming a resist pattern using the positive-type resist composition of the present invention preferably includes the steps of forming a resist film using the positive-type resist composition of the present invention as described above (resist film formation step), exposing the obtained resist film (exposure step), and developing the exposed resist film (development step). Furthermore, optionally, the method may include a step of heating the exposed resist film after the exposure step (post-exposure bake step) or a step of removing the developer after the development step (developer removal step).

[0093] <Resist Film Formation Process> In the resist film formation process, the positive-type resist composition of the present invention is applied to a workpiece such as a substrate that will be processed using the resist pattern, and the applied positive-type resist composition is dried to form a resist film. The application method and drying method are not particularly limited and can be carried out using known application and drying methods.

[0094] <Exposure Process> In the exposure process, the resist film is irradiated with ionizing radiation or the like to create the desired pattern. Known lithography devices such as electron beam lithography systems and laser lithography systems can be used for irradiating with ionizing radiation.

[0095] <Development Process> In the development process, the resist film exposed in the exposure process is brought into contact with a developer to develop the resist film and form a resist pattern on the workpiece. The method of bringing the resist film into contact with the developer is not particularly limited, and known methods such as immersion of the resist film in the developer or application of the developer to the resist film can be used. The temperature of the developer is not particularly limited, but can be, for example, between -20°C and 25°C. Furthermore, the development time can be, for example, between 30 seconds and 10 minutes.

[0096] [Developer] The developer can be appropriately selected according to the composition and properties of the positive-type resist composition used to form the resist film. Specifically, when selecting a developer, it is preferable to select one that does not dissolve the resist film before the exposure process, but can dissolve the exposed areas of the resist film after the exposure process. Note that one type of developer may be used alone, or multiple types may be mixed and used.

[0097] As for specific developing solutions, CF ３ CFHCFHCF ２ CF ３ CF ３ CF ２ CHCl ２ , CClF ２ CF ２ CHClF, C ８ F １８ Fluorine-based solvents such as (fluorine-containing solvents other than hydrofluoroether solvents); C ３ F ７ OCH ３ , C ４ F ９ OCH ３ , C ４ F ９ OC ２ H ５ , C ２ F ５ CF(OCH) ３ ) C ３ F ７Hydrofluoroether solvents such as methanol, ethanol, 1-propanol, isopropyl alcohol (also known as 2-propanol), 1-butanol, 2-methyl-1-propanol, 2-butanol, 2-methyl-2-propanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-methyl-2-butanol, 3-methyl-2-butanol, 2,2-dimethyl-1-propanol, and other alcohols having 1 to 5 carbon atoms; acetate esters having alkyl groups such as amyl acetate and hexyl acetate; mixtures of fluorinated solvents and alcohols; mixtures of fluorinated solvents and acetate esters having alkyl groups; mixtures of alcohols and acetate esters having alkyl groups; mixtures of fluorinated solvents, alcohols and acetate esters having alkyl groups; etc. can be used. Among these, from the viewpoint of further improving sensitivity in resist pattern formation and further enhancing the clarity of the resist pattern, alcohols having 1 to 5 carbon atoms are preferred, alcohols having 3 carbon atoms are more preferred, and isopropyl alcohol is even more preferred.

[0098] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. In the following description, "%" and "parts" representing quantities refer to mass unless otherwise specified. In addition, in copolymers produced by copolymerizing multiple types of monomers, the proportion of monomer units formed by polymerizing a certain monomer in the copolymer is usually equal to the ratio of that certain monomer to the total monomers used in the polymerization of the copolymer (starting ratio), unless otherwise specified. In the examples and comparative examples, various measurements and evaluations were performed by the following methods.

[0099] <Percentage of monomer units in polymer A> For polymer A obtained in the examples and comparative examples, １３The proportion of monomer units in polymer A was calculated using the 1C-NMR method. Specifically, polymer A was dissolved in chloroform-d, 99.8% (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) to a concentration of 10%, and this solution was measured using a nuclear magnetic resonance spectrometer (manufactured by JEOL Ltd., 400 MHz). From the measurement results, the proportion of each monomer unit in polymer A was calculated. <Mulliken charge of oxygen atom> The structure of compound B was optimized using a quantum chemical calculation program (Gaussian 16) at calculation level B3LYP / 6-31G(d). After structural optimization, N ＋ -O － Oxygen atom in bond (O － The Mulliken charge of the ) was confirmed. <Clarity (γ value)> Using a spin coater (Mikasa, MS-A150), the positive-type resist compositions prepared in the examples and comparative examples were coated onto a 4-inch diameter silicon wafer to a thickness of 50 nm. The coated positive-type resist compositions were then heated on a hot plate at 120°C for 1 minute to form a resist film on the silicon wafer. Then, using an electron beam lithography system (Elionix, ELS-S50), multiple line-and-space patterns (pitch 120 nm, line 90 nm) with different electron beam irradiation doses were drawn on the resist film, and development was performed using isopropyl alcohol (IPA) as the developer at a temperature of 23°C for 30 seconds. After that, drying was performed by blowing nitrogen gas. The electron beam irradiation dose was 4 μC / cm ２ From 200 μC / cm ２ Within the range of 4 μC / cm ２ The thickness was varied for each area. Next, the thickness of the resist film in the drawn area was measured using an optical film thickness meter (Lambda Ace, manufactured by SCREEN Semiconductor Solutions Inc.), and a sensitivity curve was created showing the relationship between the common logarithm of the total electron beam irradiation dose and the residual film percentage of the resist film after development (= film thickness of the resist film after development / film thickness of the resist film formed on the silicon wafer). Then, the following formula was applied to the obtained sensitivity curve (horizontal axis: common logarithm of the total electron beam irradiation dose, vertical axis: residual film percentage of the resist film (0 ≤ residual film percentage ≤ 1.00)): The γ value was determined using the following. A larger γ value indicates a steeper slope of the sensitivity curve, suggesting that a clearer pattern can be formed more effectively. Note that in the above formula, E ０ This is the logarithm of the total irradiation dose obtained when the sensitivity curve is fitted to a quadratic function in the range of residual film percentage 0.40 to 0.80, and a residual film percentage of 0 is substituted into the resulting quadratic function (a function of residual film percentage and the common logarithm of the total irradiation dose). Also, E １ This is the logarithm of the total irradiation dose obtained when a residual film percentage of 1.00 is substituted into the resulting line (a function of residual film percentage and the common logarithm of the total irradiation dose) which is an approximation of the slope of the sensitivity curve, by creating a straight line (approximation of the slope of the sensitivity curve) connecting the point with a residual film percentage of 0 and the point with a residual film percentage of 0.50 on the obtained quadratic function. The above formula represents the slope of the above line between residual film percentages of 0 and 1.00. <Sensitivity (Eth)> A resist film was formed on a silicon wafer using the positive-type resist composition prepared in the examples and comparative examples in the same manner as the evaluation method for "clarity". Then, the total electron beam irradiation dose Eth (μC / cm) at which the residual film percentage of the straight line (approximation of the slope of the sensitivity curve) obtained when calculating the γ value becomes 0 was calculated. ２ The following was calculated: A smaller Eth value indicates higher sensitivity of the resist film and higher efficiency of resist pattern formation.

[0100] (Example 1) <Preparation of Polymer A> [Preparation of an 18% solids aqueous solution of semi-hardened beef tallow fatty acid potassium soap] 100 g of ion-exchanged water was prepared and heated to 70°C while stirring, and 8.40 g of potassium hydroxide (49% aqueous solution) was added. Next, 19.6 g of beef tallow 45° hardened fatty acid HFA (manufactured by NOF Corporation) was added at an addition rate of 1.28 g / min, and then 0.126 g of potassium silicate was added. The mixture was then stirred at 80°C for more than 2 hours to obtain an 18% solids aqueous solution of semi-hardened beef tallow fatty acid potassium soap. [Synthesis of Polymer] 3 g of α-chloroacrylate-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl (ACAFPh) as monomer (a) and 1.066 g of α-methylstyrene (AMS) as monomer (b) were added to a glass ampoule containing a stirring bar. Furthermore, to the same ampoule, 6.771 g of deionized water was added to 0.5463 g of an 18% solids aqueous solution of the semi-hardened beef tallow fatty acid potassium soap prepared above to form a monomer composition. The ampoule was then sealed, and oxygen in the system was removed by repeatedly pressurizing and depressurizing with nitrogen gas 10 times. The system was then heated to 75°C, and the polymerization reaction was carried out for 1 hour. Next, 10 g of tetrahydrofuran (THF) was added to the system, and the resulting solution was added dropwise to 100 g of a mixed solvent of THF and methanol (MeOH) (THF:MeOH (mass ratio) 30:70) to precipitate the polymer. The precipitated polymer was then recovered by filtration. The obtained polymer was a polymer containing 54 mol% of α-chloroacrylate-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl units and 46 mol% of α-methylstyrene units. [Purification of Polymer] The polymer recovered by filtration was dissolved in 10 g of THF, and the resulting solution was added dropwise to 100 g of a mixed solvent of THF and MeOH (THF:MeOH (mass ratio) 34:66) to precipitate a white solidified substance (polymer containing ACAFPh units and AMS units). Subsequently, the solution containing the precipitated polymer was filtered using a Kiriyama funnel to obtain a white polymer A (polymer containing 54 mol% ACAFPh units and 46 mol% AMS units).<Preparation of Positive-Type Resist Composition> 100 parts of polymer A obtained above, 20 parts of 4-methylmorpholine N-oxide (manufactured by Tokyo Chemical Industry Co., Ltd.; Mulliken charge of oxygen atom: -0.575) as compound B, and 4200 parts of propylene glycol monomethyl ether acetate (PGMEA) and 1800 parts of 1-methoxy-2-propanol (PGME) as solvents were mixed. The resulting mixed solution was filtered through a membrane filter with a pore size of 20 nm to prepare a positive-type resist composition. Clarity (γ value) and sensitivity (Eth) were evaluated using this positive-type resist composition according to the above. The results are shown in Table 1.

[0101] (Example 2) Except for changing the amount of 4-methylmorpholine N-oxide used in the preparation of the positive resist composition from 20 parts to 10 parts, various operations, measurements, and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

[0102] (Example 3) The same procedures, measurements, and evaluations were performed as in Example 1, except that 10 parts of pyridine N-oxide (manufactured by Tokyo Chemical Industry Co., Ltd.; Mulliken charge of oxygen atom: -0.517) were used instead of 20 parts of 4-methylmorpholine N-oxide when preparing the positive-type resist composition. The results are shown in Table 1.

[0103] (Example 4) The same procedures, measurements, and evaluations were performed as in Example 1, except that 20 parts of pyridine N-oxide were used instead of 20 parts of 4-methylmorpholine N-oxide when preparing the positive-type resist composition. The results are shown in Table 1.

[0104] (Example 5) Various operations, measurements, and evaluations were carried out in the same manner as in Example 1, except that polymer A prepared as described below was used. The results are shown in Table 1. <Preparation of Polymer A> Polymer A was prepared in the same manner as in Example 1, except that 2.295 g of 3,5-bis(trifluoromethyl)-α-methylstyrene (BAMS) was used instead of 1.066 g of AMS as monomer (b). The obtained polymer A was a polymer containing 52 mol% ACAFPh units and 48 mol% BAMS units.

[0105] (Example 6) The same procedures, measurements, and evaluations were carried out as in Example 1, except that 10 parts of 2,2'-bipyridyl 1,1'-dioxide (manufactured by Tokyo Chemical Industry Co., Ltd.; Mulliken charge of oxygen atom: -0.506) were used instead of 20 parts of 4-methylmorpholine N-oxide when preparing the positive-type resist composition. The results are shown in Table 1.

[0106] (Example 7) The same procedures, measurements, and evaluations were performed as in Example 1, except that 20 parts of 2,2'-bipyridyl 1,1'-dioxide were used instead of 20 parts of 4-methylmorpholine N-oxide when preparing the positive-type resist composition. The results are shown in Table 1.

[0107] (Comparative Example 1) The same procedures, measurements, and evaluations were performed as in Example 1, except that 4-methylmorpholine N-oxide was not added during the preparation of the positive-type resist composition. The results are shown in Table 1.

[0108] (Comparative Example 2) The same procedures, measurements, and evaluations were performed as in Example 5, except that 4-methylmorpholine N-oxide was not added during the preparation of the positive-type resist composition. The results are shown in Table 1.

[0109] (Comparative Example 3) Except for changing the amount of 4-methylmorpholine N-oxide used in the preparation of the positive-type resist composition from 20 parts to 110 parts, various operations, measurements, and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

[0110] In Table 1 below, "ACAFPh" represents the α-chloroacrylate-1-phenyl-1-trifluoromethyl-2,2,2-trifluoroethyl unit, "AMS" represents the α-methylstyrene unit, "BAMS" represents the 3,5-bis(trifluoromethyl)-α-methylstyrene unit, "c-1" represents 4-methylmorpholine N-oxide (compound (c-1) described above), "c-2" represents pyridine N-oxide (compound (c-2) described above), "c-3" represents 2,2'-bipyridyl 1,1'-dioxide (compound (c-3) described above), "PGMEA" represents propylene glycol monomethyl ether acetate, "PGME" represents 1-methoxy-2-propanol, and "Poor coating" indicates that evaluation could not be performed due to poor coating when forming the resist film using the positive-type resist composition. Furthermore, in Table 1, the concentration (mass%) of compound B is shown rounded to the third decimal place.

[0111]

[0112] According to the present invention, it is possible to provide a positive-type resist composition that can form highly clear resist patterns with high sensitivity.

Claims

1. A positive-type resist composition comprising polymer A and compound B, wherein polymer A is a main-chain cleavage type polymer, and compound B is of the following formula (I): [In formula (I), R １ ~R ３ Two or more of these may be bonded together to form a ring structure which may have substituents, and R may not form a ring structure １ ~R ３ Each of these is independently a hydrogen atom, a halogen atom, or an organic group, and may be the same or different from each other. The content of polymer A is expressed as W Ａ The content of compound B is W Ｂ As, W Ａ ≧W Ｂ A positive-type resist composition that satisfies the following conditions.

2. R １ ~R ３ The positive resist composition according to claim 1, wherein two or more of R １ to R ３ are combined to form a ring structure which may have a substituent.

3. Compound B is represented by the following formulas (II) to (V): [In formula (II), R ４ ~R ８ Each of these independently comprises a hydrogen atom, a halogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, a nitro group, a cyano group, an optionally substituted ketone group, an optionally substituted aryl group, and NR ａ R ｂ (R ａ ~R ｂ Each is independently a hydrogen atom or an alkyl group, and may be the same or different from each other. Selected from the group consisting of ), which may be the same or different from each other, in formula (III), R ９ ~R １４ Each of these independently comprises a hydrogen atom, a halogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, a nitro group, a cyano group, an optionally substituted ketone group, an optionally substituted aryl group, and NR ａ R ｂ (R ａ ~R ｂ Each of these is independently a hydrogen atom or an alkyl group, and may be the same or different from each other. Selected from the group consisting of ), which may be the same or different from each other, in formula (IV), R １５ ~R １９ Each of these independently comprises a hydrogen atom, a halogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, a nitro group, a cyano group, an optionally substituted ketone group, an optionally substituted aryl group, and NR ａ R ｂ (R ａ ~R ｂ Each is independently a hydrogen atom or an alkyl group, and may be the same or different from each other. Selected from the group consisting of ), which may be the same or different from each other, where L is a single bond or a divalent linking group, R ２０ ~R ２１ Each of these independently comprises a halogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, a nitro group, a cyano group, an optionally substituted ketone group, an optionally substituted aryl group, and NR ａ R ｂ (R ａ ~R ｂ Each of these is independently a hydrogen atom or an alkyl group, and they may be the same or different from each other.) are selected from the group consisting of ), and they may be the same or different from each other, and p is an integer between 0 and 4, and when p is 2 or more there are p R ２０ The elements may be identical or different from each other, q is an integer between 0 and 4 (inclusive), and when q is 2 or greater, there are q elements R. ２１ The positive-type resist composition according to claim 1, which is represented by either of the following: ].

4. The positive resist composition according to claim 1, wherein the content of compound B is 5 parts by mass or more and 50 parts by mass or less per 100 parts by mass of polymer A.

5. The positive-type resist composition according to any one of claims 1 to 4, wherein the molecular weight of compound B is 2000 or less.

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