Radiation-sensitive composition, pattern forming method, polymer, and compound

Abstract

Provided are a radiation-sensitive composition, a pattern forming method, a polymer, and a compound which are excellent in terms of sensitivity, CDU, LWR, MEEF, development defect suppression, and pattern rectangularity during pattern formation. The radiation-sensitive composition contains a polymer including a structural unit (I) derived from a compound represented by formula (1), and a solvent. (In formula (1), R1 is a C1-C40 monovalent organic group. Here, when A- is-SO3 -, R1 is a C3-C40 monovalent organic group including a cyclic structure. A- is –SO3 -, -COO-, or –N--SO2-RX. RX is a C1-C20 monovalent organic group. R2 is a hydrogen atom or a C1-C20 monovalent organic group. R3 is hydroxy or a C1-C20 monovalent organic group. Here, any one of R1-R6 has one polymerizable group.)

Description

Radiation-sensitive compositions, pattern-forming methods, polymers, and compounds

[0001] The present invention relates to radiation-sensitive compositions, pattern-forming methods, polymers, and compounds.

[0002] Photolithography, which uses resist compositions, is employed to form fine circuits in semiconductor devices. A typical procedure involves, for example, generating acid by irradiating a resist composition film with radiation through a mask pattern. This acid then acts as a catalyst, creating a difference in the solubility of the polymer in alkaline or organic developers between the exposed and unexposed areas, thereby forming a resist pattern on the substrate.

[0003] The above-mentioned photolithography techniques utilize short-wavelength radiation such as ArF excimer lasers, and further advance pattern miniaturization by employing liquid immersion lithography, a method in which exposure is performed with the space between the lens of the exposure apparatus and the resist film filled with a liquid medium. As next-generation technologies, lithography using even shorter-wavelength radiation such as electron beams, X-rays, and EUV (extreme ultraviolet) is also being considered.

[0004] A technique is being investigated for introducing a photoacid generator, which is a photosensitive component that is a major component of resist compositions, into a polymer (see Japanese Patent Publication No. 5830503).

[0005] Patent No. 5830503

[0006] As patterns become finer, resist compositions are required to have resist performance equivalent to or better than conventional ones, in terms of sensitivity, critical dimension uniformity (CDU), an indicator of hole diameter uniformity; LWR (Line Width Roughness), which indicates the variation in line width and resist pattern line width; mask error enhancement factor (MEEF), which is the change in line width and hole diameter in response to the change in mask size; development defect suppression; and pattern rectangularity, which indicates the rectangularity of the cross-sectional shape of the resist pattern.

[0007] The present invention aims to provide a radiation-sensitive composition, a pattern forming method, a polymer, and a compound that are excellent in sensitivity, CDU, LWR, MEEF, development defect suppression, and pattern rectangularity during pattern formation.

[0008] As a result of intensive studies to solve this problem, the present inventors have found that the above object can be achieved by adopting the following configuration, and have completed the present invention.

[0009] That is, in one embodiment, the present invention relates to a radiation-sensitive composition containing a polymer containing a structural unit (I) derived from a compound represented by the following formula (1) and a solvent. (In formula (1), １ R is a monovalent organic group having 1 to 40 carbon atoms. However, when - A is -SO ３ - R is a monovalent organic group having 3 to 40 carbon atoms containing a cyclic structure. １ A is -SO - ３ - - -COO - or -N - -SO ２ -R Ｘ where R is a monovalent organic group having 1 to 20 carbon atoms. Ｘ R is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. ２ R is a hydroxy group or a monovalent organic group having 1 to 20 carbon atoms. ３ R and ４ R are each independently a monovalent organic group having 1 to 20 carbon atoms, or ５ R and ４ R together represent a ring structure having 4 to 12 carbon atoms formed together with the sulfur atom to which they are attached. ５ R is a halogen atom, a hydroxy group, a nitro group, an amino group, a carboxy group, a cyano group, or a monovalent organic group having 1 to 20 carbon atoms. When there are a plurality of ６ R, the plurality of ６ R are the same or different from each other. However, ６ R <00000​One of them has one polymerizable group. m is 0 or 1. If m is 1, R ３ -CO- and R ２ Both -O- atoms bond to the six-membered ring structure to which the sulfur atom in formula (1) above is bonded. (n is an integer from 0 to 4.)

[0010] In this radiation-sensitive composition, a structural unit (I) having a specific onium salt (sulfonium salt) structure as an acid-generating structure is introduced into the polymer, thereby enabling excellent sensitivity, CDU, LWR, MEEF, development defect suppression, and pattern rectangularity during pattern formation. The reason for this is not bound by any theory, but is presumed to be as follows: Since substituents having ester bonds are bonded to the aromatic ring of the sulfonium cation of the onium salt structure, along with substituents having ether bonds, the polarity of the entire polymer is increased. This improves solubility in the developer, thereby improving dissolution contrast. Furthermore, since bonds that can expand the conjugated system, such as ether bonds and ester bonds, are bonded to the aromatic ring, the light absorption efficiency of the sulfonium cation is improved, and the acid generation efficiency from the onium salt structure of structural unit (I) can be increased. Moreover, since the onium salt structure as an acid-generating structure is introduced as a structural unit of the polymer, the diffusion length of the generated acid can be appropriately controlled. It is presumed that the above-mentioned resist properties can be exhibited through the combined effects of these factors.

[0011] In another embodiment, the present invention relates to a pattern forming method comprising the steps of: applying the radiation-sensitive composition directly or indirectly to a substrate to form a resist film; exposing the resist film to light; and developing the exposed resist film with a developer.

[0012] In this pattern formation method, since the above-mentioned radiation-sensitive composition, which has excellent sensitivity, CDU, LWR, MEEF, development defect suppression, and pattern rectangularity, is used during pattern formation, high-quality resist patterns can be efficiently formed.

[0013] In another embodiment, the present invention relates to a polymer comprising a structural unit (I) derived from a compound represented by the following formula (1). (In formula (1), R １ A is a monovalent organic group having 1 to 40 carbon atoms. However, A - ga-SO ３ - If R １ A is a monovalent organic group with 3 to 40 carbon atoms that includes a cyclic structure. - is, -SO ３ - ,-COO - or -N - -SO ２ -R Ｘ That is. R Ｘ R is a monovalent organic group having 1 to 20 carbon atoms. ２ R is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. ３ R is a hydroxyl group or a monovalent organic group having 1 to 20 carbon atoms. ４ and R ５ Each of these is independently a monovalent organic group having 1 to 20 carbon atoms, or R ４ and R ５ These can be combined to form a ring structure with 4 to 12 carbon atoms, along with the sulfur atoms to which they are bonded. ６ R is a halogen atom, hydroxyl group, nitro group, amino group, carboxyl group, cyano group, or a monovalent organic group having 1 to 20 carbon atoms. ６ If multiple R ６ They are either identical or different from each other. However, R １ ~R ６ One of them has one polymerizable group. m is 0 or 1. If m is 1, R ３ -CO- and R ２ Both -O- atoms bond to the six-membered ring structure to which the sulfur atom in formula (1) above is bonded. (n is an integer from 0 to 4.)

[0014] In this polymer, by introducing a specific onium salt structure as the acid-generating structure into structural unit (I), it can exhibit the developer affinity, dispersibility, acid generation efficiency, and acid diffusion length described above, making it suitable as a polymer that is the main component of a radiation-sensitive composition.

[0015] In yet another embodiment, the present invention relates to a compound represented by the following formula (1). (In formula (1), R １ A is a monovalent organic group having 1 to 40 carbon atoms. However, A - ga-SO ３ - If R １ A is a monovalent organic group with 3 to 40 carbon atoms that includes a cyclic structure. - is, -SO ３ - ,-COO - or -N - -SO ２ -R Ｘ That is. R Ｘ R is a monovalent organic group having 1 to 20 carbon atoms. ２ R is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. ３ R is a hydroxyl group or a monovalent organic group having 1 to 20 carbon atoms. ４ and R ５ Each of these is independently a monovalent organic group having 1 to 20 carbon atoms, or R ４ and R ５ These can be combined to form a ring structure with 4 to 12 carbon atoms, along with the sulfur atoms to which they are bonded. ６ R is a halogen atom, hydroxyl group, nitro group, amino group, carboxyl group, cyano group, or a monovalent organic group having 1 to 20 carbon atoms. ６ If multiple R ６ They are either identical or different from each other. However, R １ ~R ６ One of them has one polymerizable group. m is 0 or 1. If m is 1, R ３ -CO- and R ２ Both -O- atoms bond to the six-membered ring structure to which the sulfur atom in formula (1) above is bonded. (n is an integer from 0 to 4.)

[0016] Because the compound possesses the developer affinity, dispersibility, acid generation efficiency, and acid diffusion length described above, it is suitable as a monomer compound that provides structural units for polymers.

[0017] In this specification, "organic group" means a group containing at least one carbon atom (excluding groups that constitute a functional or characteristic group on their own, such as cyano groups and ketone groups). "Fused ring structure" means a structure in which adjacent rings share one edge (two adjacent atoms). "Bridged ring hydrocarbon group" means a polycyclic cyclic hydrocarbon group in which two non-adjacent carbon atoms constituting the ring are bonded together by a linking group containing one or more carbon atoms.

[0018] The embodiments of the present invention will be described in detail below, but the present invention is not limited to these embodiments. A combination of preferred embodiments is also preferable.

[0019] <Radiation-sensitive composition> The radiation-sensitive composition according to this embodiment (hereinafter also simply referred to as "composition") comprises a polymer (hereinafter also referred to as "base polymer") and a solvent. The above composition may also contain other optional components such as a radiation-sensitive acid generator and an acid diffusion control agent, as long as they do not impair the effects of the present invention.

[0020] (Polymer) A polymer (i.e., a base polymer) is an aggregate of polymer chains containing structural unit (I) derived from the compound represented by formula (1) above. In addition to structural unit (I), the base polymer may also contain structural units (II) having an acid-dissociable group, structural units (III) having a phenolic hydroxyl group, structural units (IV) containing at least one selected from the group consisting of lactone structures, cyclic carbonate structures, and sultone structures, structural units (V) containing a polar group, and so on. Each structural unit will be described below.

[0021] [Structural Unit (I)] Structural unit (I) is a structural unit derived from the compound represented by formula (1) above. As represented by formula (1) above, structural unit (I) contains an organic acid anion and a sulfonium cation and functions as a radiation-sensitive acid generation structure or an acid diffusion control structure. When it functions as a radiation-sensitive acid generation structure, it is also called structural unit (I-1), and when it functions as an acid diffusion control structure, it is also called structural unit (I-2). The distinction between these functions is determined by the organic acid anion. First, the polymerizable group contained in either the organic acid anion or the sulfonium cation will be explained, followed by the sulfonium cation and the organic acid anion in that order.

[0022] In the above formula (1), R １ ~R ６ Each of these has one polymerizable group. Examples of polymerizable groups include an ethylenically unsaturated double bond, or a structure that includes an ethylenically unsaturated double bond as a substructure constituting a ring. The polymerizable group may have substituents.

[0023] Examples of substituents when the polymerizable group has substituents include halogen atoms, monovalent organic groups having 1 to 20 carbon atoms, hydroxyl groups, carboxyl groups, cyano groups, nitro groups, and oxo groups (=O).

[0024] Examples of halogen atoms include fluorine, chlorine, bromine, and iodine.

[0025] Examples of the monovalent organic groups having 1 to 20 carbon atoms include monovalent hydrocarbon groups having 1 to 20 carbon atoms, groups (a) having a divalent heteroatom-containing group between carbon atoms (between two adjacent or non-adjacent carbon atoms) or at the end of the hydrocarbon group, groups in which some or all of the hydrogen atoms of the hydrocarbon group or group (a) are replaced with monovalent heteroatom-containing groups, or combinations thereof.

[0026] Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms include monovalent linear hydrocarbon groups having 1 to 20 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, or combinations thereof.

[0027] Examples of monovalent chain hydrocarbon groups having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, s-butyl, and t-butyl groups; alkenyl groups such as ethenyl, propenyl, and butenyl groups; and alkynyl groups such as ethynyl, propynyl, and butynyl groups.

[0028] Examples of monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms include cycloalkyl groups such as cyclopentyl and cyclohexyl groups; cycloalkenyl groups such as cyclopropenyl, cyclopentenyl, and cyclohexenyl groups; bridged ring saturated hydrocarbon groups such as norbornyl, adamantyl, and tricyclodecyl groups; and bridged ring unsaturated hydrocarbon groups such as norbornyl and tricyclodecenyl groups.

[0029] Examples of monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xyl, naphthyl, and anthryl groups, and aralkyl groups such as benzyl, phenethyl, naphthylmethyl, and anthrylmethyl groups.

[0030] Examples of heteroatoms that constitute a divalent or monovalent heteroatom-containing group include oxygen, nitrogen, sulfur, phosphorus, silicon, and halogen atoms. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms.

[0031] Examples of divalent heteroatom-containing groups include -CO-, -CS-, -NR'-, -O-, -S-, and combinations thereof. R' is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms.

[0032] Examples of monovalent heteroatom-containing groups include hydroxyl groups, carboxyl groups, sulfanyl groups, cyano groups, nitro groups, and halogen atoms. Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

[0033] Specific examples of the polymerizable group mentioned above include, but are not limited to, structures represented by the following formula.

[0034] (In the formula, * represents a bond with an atom constituting R １ ~R ６ .)

[0035] In the above formula (1), as the monovalent organic group having 1 to 20 carbon atoms represented by R ２ the monovalent organic group having 1 to 20 carbon atoms shown in the above polymerizable group can be preferably employed.

[0036] As R ２ in addition to the above polymerizable group, a hydrogen atom, an alkyl group, an acyl group, an alkoxycarbonylalkyl group, a cycloalkoxycarbonylalkyl group, an alkoxyalkyl group, a lactone structure-containing group (a group obtained by removing one hydrogen atom from the lactone structure), a group in which a hydrogen atom of these groups is substituted with the above monovalent heteroatom-containing group, or a combination thereof is preferable. Among them, as R ２ a hydrogen atom, a methyl group, an ethyl group, a carboxymethyl group, a t-butoxycarbonylmethyl group, a methylcyclopentyloxycarbonylmethyl group, an ethylcyclopentyloxycarbonylmethyl group, a methyladamantyloxycarbonylmethyl group, an ethyladamantyloxycarbonylmethyl group, an acetyl group, a pivaloyl group are preferable.

[0037] When R ２ has a polymerizable group, it is preferably introduced as a (meth)acryloyl group.

[0038] As the monovalent organic group having 1 to 20 carbon atoms represented by R ３ the monovalent organic group having 1 to 20 carbon atoms represented by R ２ can be preferably employed. R ３ is preferably a monovalent organic group having 1 to 20 carbon atoms having an ether bond on the bonding hand side.

[0039] As R ３Examples include a hydroxy group, an alkyl group, a cycloalkyl group, an alkoxy group, a cycloalkyloxy group, an alkoxycarbonylalkyloxy group, a cycloalkoxycarbonylalkyloxy group, a lactone structure-containing group (a group obtained by removing one hydrogen atom from the lactone structure), a group in which a hydrogen atom of these groups is substituted with the above-mentioned monovalent heteroatom-containing group, or a combination thereof. Among them, R ３ Examples include a hydroxy group, a methoxy group, an ethoxy group, a 2,2,2-trifluoroethoxy group, a t-butoxy group, a t-amyloxy group, a methylcyclopentyloxy group, an ethylcyclopentyloxy group, a t-butoxycarbonylmethyloxy group, a methylcyclopentyloxycarbonylmethyloxy group, an ethylcyclopentyloxycarbonylmethyloxy group, a methyladamantyloxycarbonylmethyloxy group, and an ethyladamantyloxycarbonylmethyloxy group. Also, R ３ Preferably contains an acid dissociable group.

[0040] In the above formula (1), R ２ For -O-, R ３ -CO is preferably in an ortho or para position relationship, and more preferably in an ortho position relationship. This makes it possible to appropriately control the acid generation efficiency and exhibit the above-mentioned various resist performances at a higher level.

[0041] R ４ and R ５ As the monovalent organic group having 1 to 20 carbon atoms represented by, a monovalent organic group having 1 to 20 carbon atoms represented by R ２ can be preferably employed.

[0042] R ４ and R ５Examples of C4-C12 ring structures formed by combining these elements with the sulfur atoms to which they bond include C4-C12 sulfur atom-containing aliphatic heterocyclic structures and C4-C12 sulfur atom-containing aromatic heterocyclic structures. Examples of the above sulfur atom-containing aliphatic heterocyclic structures include thiethane, tetrahydrothiophene, oxathiolane, thiane, dithiane, thiomorpholine, and thioxane. Examples of the above sulfur atom-containing aromatic heterocyclic structures include thiophene, thiazole, benzothiophene, dibenzothiophene, and phenoxathiin. Among these, R ４ and R ５ Tetrahydrothiophene, thioxane, dibenzothiophene, benzothiophene, and phenoxatiin are more preferred as the above-mentioned ring structure.

[0043] R ４ and R ５ The above-mentioned ring structure may have substituents. Examples of substituents include halogen atoms such as fluorine, chlorine, bromine, and iodine atoms; hydroxyl groups; carboxyl groups; cyano groups; nitro groups; alkyl groups, alkoxy groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, acyl groups, acyloxy groups, or groups in which the hydrogen atoms of these groups are substituted with halogen atoms; oxo groups (=O), etc.

[0044] R ４ and R ５ Each of these is preferably a substituted or unsubstituted phenyl group. ４ and R ５ The phenyl group in R ４ and R ５ The above ring structure composed of may have substituents. ４ and R ５ Preferred substituents on the phenyl group in this compound are alkyl groups, halogen atoms, and alkyl halides, with methyl groups, t-butyl groups, fluoro groups, iodo groups, and trifluoromethyl groups being more preferred.

[0045] R ４ or R ５If the polymerizable group is present, it is preferable to introduce it as a (meth)acryloyl group.

[0046] R ６ As a monovalent organic group having 1 to 20 carbon atoms, R ２ A monovalent organic group having 1 to 20 carbon atoms, represented by [the formula shown], can be suitably used.

[0047] R ６ Preferably, alkyl groups, halogen atoms, and alkyl halides are used, and more preferably, methyl groups, t-butyl groups, fluoro groups, iodo groups, and trifluoromethyl groups.

[0048] m is preferably 0.

[0049] n is preferably an integer between 0 and 3, more preferably an integer between 0 and 2, and even more preferably 0 or 1.

[0050] Specific examples of sulfonium cations in an onium salt structure include, but are not limited to, structures represented by the following formulas (a-1) to (a-134).

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059]

[0060]

[0061]

[0062]

[0063]

[0064]

[0065]

[0066] The onium salt structure formed by the organic acid anion and organic cation of structural unit (I) functions as either a radiation-sensitive acid generation structure or an acid diffusion control structure, depending on the structure of the organic acid anion, as described above. The radiation-sensitive acid generation structure is a structure that generates an acid that dissociates the acid-dissociable group when the polymer contains a structural unit having an acid-dissociable group, upon exposure. The acid diffusion control structure is a structure that generates an acid that does not dissociate the acid-dissociable group upon exposure, and has the function of suppressing the diffusion of acid generated from the radiation-sensitive acid generation structure or, if necessary, the radiation-sensitive acid generator in the unexposed areas. The acid generated from the acid diffusion control structure can be said to be a relatively weaker acid (an acid with a high pKa) than the acid generated from the radiation-sensitive acid generation structure. Whether the onium salt structure in structural unit (I) functions as a radiation-sensitive acid generation structure or an acid diffusion control structure depends on the energy required for the dissociation of the acid-dissociable group of the base polymer, and the acidity of the acid generated upon exposure, etc.

[0067] Acids generated by exposure include sulfonic acids, sulfonimides, carboxylic acids, and sulfonamides. Organic acid anions can employ structures corresponding to these.

[0068] Examples of such acids include: (1) a structure in which one or more cyano groups, fluorine atoms, or fluorinated hydrocarbon groups are substituted on the α or β carbon atoms of the sulfur atom of the sulfo group; (2) a structure having a sulfonimide structure containing a fluorine atom; and (3) a structure in which neither the α nor β carbon atoms of the sulfur atom of the sulfo group are substituted with a cyano group, fluorine atom, or fluorinated hydrocarbon group. Examples of carboxylic acids generated by exposure include: (4) a structure in which one or more fluorine atoms or fluorinated hydrocarbon groups are substituted on the carbon atoms adjacent to the carboxyl group; (5) a structure in which the carbon atoms adjacent to the carboxyl group are not substituted with a fluorine atom or fluorinated hydrocarbon group; and (6) a structure having a sulfonamide structure which may contain a fluorine atom.

[0069] Of these, the radiation-sensitive acid-generating structure of structural unit (I-1) is preferably one that corresponds to (1) to (2) above. The acid diffusion-controlling structure of structural unit (I-2) is preferably one that corresponds to (3) to (6) above, with (3) or (5) being particularly preferred.

[0070] The organic acid anion of the monomer compound that gives structural unit (I-1) is preferably represented by the following formula (z-a). (In formula (z-a), R ｚａ It is a divalent organic group with 3 to 40 carbon atoms that includes a cyclic structure. However, -SO ３ - R relative to the sulfur atom inside １ (A cyano group, fluorine atom, or fluorinated hydrocarbon group is bonded to the α-carbon or β-carbon in the molecule.)

[0071] The organic group is not particularly limited and may be a group containing only a cyclic structure or a group combining a cyclic structure and a chain structure. The cyclic structure may be monocyclic, polycyclic, or a combination thereof. The cyclic structure may also be an alicyclic structure, an aromatic ring structure, or a combination thereof. In the case of a combination, the cyclic structure may be linked by a chain structure, or two or more cyclic structures may form a fused ring structure. These structures are preferably included as the smallest basic skeleton of the cyclic structure. The number of cyclic structures as the basic skeleton in the organic group may be one or two or more. The divalent heteroatom-containing group may be present between carbon atoms or at the ends of carbon chains forming the skeleton of the cyclic or chain structure, and hydrogen atoms on carbon atoms of the cyclic or chain structure may be substituted with other substituents.

[0072] R １ Preferably, it includes at least one structure selected from the group consisting of a carbonyl group and an ether bond, and a cyclic structure.

[0073] The above alicyclic structure is R in formula (1) above. ２ A structure corresponding to a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms can be suitably adopted.

[0074] The above aromatic ring structure is R in formula (1) above. ２ Structures corresponding to monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms can be suitably adopted. In addition, aromatic heterocycles such as furan rings, pyrrole rings, thiophene rings, phosphole rings, pyrazole rings, oxazole rings, isoxazole rings, thiazole rings, pyridine rings, pyrazine rings, pyrimidine rings, pyridazine rings, and triazine rings are also suitable.

[0075] The above chain-like structure is R in formula (1) above. ２ A structure corresponding to a monovalent chain hydrocarbon group having 1 to 20 carbon atoms can be suitably adopted.

[0076] Aliphatic heterocyclic structures can also be used as the alicyclic structures described above. Examples of such aliphatic heterocyclic structures include oxygen-containing aliphatic heterocyclic structures such as oxirane, tetrahydrofuran, tetrahydropyran, dioxolane, and dioxane; nitrogen-containing aliphatic heterocyclic structures such as aziridine, pyrrolidine, piperidine, and piperazine; sulfur-containing aliphatic heterocyclic structures such as thiethane, thiolane, and thian; and aliphatic heterocyclic structures containing multiple heteroatoms such as morpholine, 1,2-oxathiolane, and 1,3-oxathiolane.

[0077] Aliphatic heterocyclic structures include lactone structures, cyclic carbonate structures, sultone structures, cyclic acetal structures, cyclic imide structures, or combinations thereof.

[0078] As substituents that substitute hydrogen atoms on carbon atoms in the above cyclic or chain structure, R ４ and R ５ The substituents that the above-mentioned ring structure can have can be suitably adopted.

[0079] Examples of the above-mentioned monovalent fluorinated hydrocarbon groups include monovalent fluorinated chain hydrocarbon groups having 1 to 20 carbon atoms and monovalent fluorinated alicyclic hydrocarbon groups having 3 to 20 carbon atoms.

[0080] Examples of the above-mentioned monovalent fluorinated chain hydrocarbon groups having 1 to 20 carbon atoms include fluorinated alkyl groups such as trifluoromethyl group, difluoromethyl group, 2,2,2-trifluoroethyl group, pentafluoroethyl group, 2,2,3,3,3-pentafluoropropyl group, 1,1,1,3,3,3-hexafluoropropyl group, heptafluoron-propyl group, heptafluoroisopropyl group, nonafluoron-butyl group, nonafluoroisobutyl group, nonafluorot-butyl group, 2,2,3,3,4,4,5,5-octafluoron-pentyl group, tridecafluoron-hexyl group, and 5,5,5-trifluoro-1,1-diethylpentyl group; fluorinated alkenyl groups such as trifluoroethenyl group and pentafluoropropenyl group; and fluorinated alkynyl groups such as fluoroethynyl group and trifluoropropynyl group.

[0081] Examples of the above-mentioned monovalent fluorinated alicyclic hydrocarbon groups having 3 to 20 carbon atoms include fluorinated cycloalkyl groups such as fluorocyclopentyl group, difluorocyclopentyl group, nonafluorocyclopentyl group, fluorocyclohexyl group, difluorocyclohexyl group, undecafluorocyclohexylmethyl group, fluoronorbornyl group, fluoroadamantyl group, fluorobornyl group, fluoroisobornyl group, and fluorotricyclodecyl group; and fluorinated cycloalkenyl groups such as fluorocyclopentenyl group and nonafluorocyclohexenyl group.

[0082] The above-mentioned fluorinated hydrocarbon group is preferably a monovalent fluorinated linear hydrocarbon group having 1 to 8 carbon atoms, and more preferably a monovalent fluorinated linear hydrocarbon group having 1 to 5 carbon atoms.

[0083] The organic acid anion of the monomer compound that gives structural unit (I-1) preferably has the structure represented by the following formula (Z1). (In formula (Z1), W is a polymerizable group. L) １１ This is a single bond or a divalent heteroatom-containing group. Cy １１ and Cy １２ These are, independently, substituted or unsubstituted cyclic structures. １２ If there are multiple Cy １２ They are either identical or different from each other. １２ and L １３ Each of these is independently a single bond, a substituted or unsubstituted divalent hydrocarbon group having 1 to 10 carbon atoms, a divalent heteroatom-containing group, or a combination thereof. １２ If there are multiple L １２ They are either identical or different from each other. ｆ１ and R ｆ２ Each of these is independently a hydrogen atom, a cyano group, a fluorine atom, or a fluorinated hydrocarbon group. However, R ｆ１ and R ｆ２ At least one selected from the group consisting of the following is a cyano group, a fluorine atom, or a fluorinated hydrocarbon group. z11 is 0 or 1. z12 is an integer from 0 to 3. z13 is an integer from 1 to 4.

[0084] The polymerizable group represented by W can preferably be the polymerizable group shown in formula (1) above.

[0085] L １１ ~L １３ As the divalent heteroatom-containing group represented by the above formula (1), the divalent heteroatom-containing group shown in the polymerizable group of formula (1) can be suitably adopted.

[0086] Cy １１ and Cy １２ The cyclic structure represented by the above formula (z-a) is R ｚａ The cyclic structure shown can be suitably adopted. Substituents that the cyclic structure may have include R in formula (1) above. ４ and R ５ The substituents that the ring structure composed of can have can be suitably adopted.

[0087] L １２ and L １３ As the divalent hydrocarbon group having 1 to 10 carbon atoms in the polymerizable group of formula (1) above, a group obtained by removing one hydrogen atom from the group corresponding to 1 to 10 carbon atoms among the monovalent hydrocarbon groups having 1 to 20 carbon atoms shown above. The substituents that the hydrocarbon group may have are R in formula (1) above. ４ and R ５ The substituents that the ring structure composed of can have can be suitably adopted.

[0088] R ｆ１ and R ｆ２ As the fluorinated hydrocarbon group represented by the above formula (z-a), the fluorinated hydrocarbon group shown can be suitably adopted.

[0089] z11 is preferably 1. z12 is preferably an integer between 0 and 2, and more preferably 0 or 1. z13 is preferably an integer between 1 and 3, and more preferably 1 or 2.

[0090] Specific examples of organic acid anions of monomeric compounds that give structural unit (I-1) include, but are not limited to, structures represented by the following formulas (z-1-1) to (z-1-56) (including the structures represented by the above formulas (z-a) and (Z1)).

[0091]

[0092]

[0093]

[0094]

[0095]

[0096]

[0097]

[0098] The monomeric compound that gives structural unit (I-1) is obtained by combining the above-mentioned organic acid anion (sulfonic acid anion, sulfonimide anion, etc.) with the above-mentioned sulfonium cation. Specific examples, though not limited to them, include structures represented by the following formulas (A-1) to (A-54).

[0099]

[0100]

[0101]

[0102]

[0103]

[0104]

[0105] When the base polymer has structural unit (I-1), the lower limit of the content of structural unit (I-1) in the total structural units constituting the polymer (total percentage if multiple types exist) is preferably 1 mol%, more preferably 2 mol%, and still more preferably 3 mol%. The upper limit of the above content is preferably 30 mol%, more preferably 25 mol%, and still more preferably 20 mol%. As a result, the composition can exhibit excellent sensitivity, CDU, LWR, MEEF, development defect suppression, and pattern rectangularity during pattern formation.

[0106] As long as the effects of the present invention are not impaired, the polymer may contain known structural units having an onium salt structure as a radiation-sensitive acid-generating structure, in addition to structural unit (I-1).

[0107] The organic acid anion of the monomer compound that gives structural unit (I-2) is preferably represented by the following formula (z-b) or (z-c). (In equations (z-b) and (z-c), R ｚｂ and R ｚｃ These are, independently, monovalent organic groups having 1 to 40 carbon atoms. However, in formula (z-c), -SO ３ - R relative to the sulfur atom inside ｚｃ Neither the α-carbon nor the β-carbon in the molecule has a cyano group, fluorine atom, or fluorinated hydrocarbon group bonded to it.

[0108] R ｚｂ and R ｚｃ As the monovalent organic group having 1 to 40 carbon atoms represented by the formula (1) above, the monovalent organic group having 1 to 40 carbon atoms shown in the polymerizable group of formula (1) above can be suitably adopted.

[0109] R ｚｂ and R ｚｃ It is preferable that it includes at least one structure selected from the group consisting of a carbonyl group and an ether bond, and a cyclic structure. ｚｂ and R ｚｃ The ring structure is R in the above formula (z-a). ｚａ A ring-shaped structure can be suitably adopted in this case.

[0110] The organic acid anion of the monomer compound that gives structural unit (I-2) preferably has a structure represented by the following formula (Z2) or formula (Z3).

[0111] (In formulas (Z2) and (Z3), W is a polymerizable group. L) ２１ and L ３１ Each of these is independently a single bond or a divalent heteroatom-containing group. Cy ２１ and Cy ２２ And Cy ３１ and Cy ３２ These are, independently, substituted or unsubstituted cyclic structures. ２２ and Cy ３２ If there are multiple Cy ２２ and Cy ３２ Each is either identical or different from the others. ２２ and L ２３ and L ３２ and L ３３ Each of these is independently a single bond, a substituted or unsubstituted divalent hydrocarbon group having 1 to 10 carbon atoms, a divalent heteroatom-containing group, or a combination thereof. ２２ and L ３２ If there are multiple L ２２ and L ３２ These are either identical or different from each other. However, -SO in formula (Z3) ３ - L relative to the sulfur atom inside ３３ The α-carbon or β-carbon in the molecule is not bonded to a cyano group, fluorine atom, or fluorinated hydrocarbon group. z21 and z31 are independently 0 or 1. z22 and z32 are independently integers between 0 and 3.

[0112] The polymerizable group represented by W can preferably be the polymerizable group shown in formula (1) above.

[0113] L ２１ ~L ２３ and L ３１ ~L ３３ As the divalent heteroatom-containing group represented by the above formula (1), the divalent heteroatom-containing group shown in the polymerizable group of formula (1) can be suitably adopted.

[0114] Cy ２１ and Cy ２２ And Cy ３１ and Cy ３２ The cyclic structure represented by the above formula (z-a) is R ｚａ The cyclic structure shown can be suitably adopted. Substituents that the cyclic structure may have include R in formula (1) above. ４ and R ５ The substituents that the ring structure composed of can have can be suitably adopted.

[0115] L ２２ and L ２３ and L ３２ and L ３３ As the divalent hydrocarbon group having 1 to 10 carbon atoms in the polymerizable group of formula (1) above, a group obtained by removing one hydrogen atom from the group corresponding to 1 to 10 carbon atoms among the monovalent hydrocarbon groups having 1 to 20 carbon atoms shown above. The substituents that the hydrocarbon group may have are R in formula (1) above. ４ and R ５ The substituents that the ring structure composed of can have can be suitably adopted.

[0116] z21 and z31 are preferably 1. z22 and z32 are each independently preferably integers between 0 and 2, and more preferably 0 or 1.

[0117] Specific examples of organic acid anions of monomeric compounds that give structural unit (I-2) include, but are not limited to, structures represented by the following formulas (z-2-1) to (z-2-30) (including structures represented by the above formulas (z-b) and (z-c)).

[0118]

[0119]

[0120]

[0121]

[0122] The monomeric compound that gives structural unit (I-2) can be obtained by arbitrarily combining the above-mentioned sulfonium cation and the above-mentioned organic acid anion when it functions as an acid diffusion control structure. Specific examples, though not limited to them, include structures represented by the following formulas (B-1) to (B-28).

[0123]

[0124]

[0125]

[0126]

[0127] When the base polymer has structural unit (I-2), the lower limit of the content of structural unit (I) in the total structural units constituting the polymer (total percentage if multiple types exist) is preferably 1 mol%, more preferably 2 mol%, and still more preferably 3 mol%. The upper limit of the above content is preferably 20 mol%, more preferably 18 mol%, and still more preferably 16 mol%. As a result, the composition can exhibit excellent sensitivity, CDU, LWR, MEEF, development defect suppression, and pattern rectangularity during pattern formation.

[0128] The composition may contain known acid diffusion control agents other than the onium salt compound (1) as an acid diffusion control agent, as long as it does not impair the effects of the present invention.

[0129] (Synthesis method for monomer compounds that give structural unit (I)) Monomer compounds that give structural unit (I) can typically be synthesized according to the following scheme. In formula (1) above, R ４ and R ５ It is an aryl group, and both m and n are 0, R ２ -O- vs R ３ This section describes the case where -CO- is bonded to the ortho position. However, it is not limited to this case, and known methods can be employed.

[0130]

[0131] In the scheme, R ２ ~R ３ and A- This is equivalent to formula (1) above. Ar is an aryl group. TfO - This is a trifluorosulfonate anion. ＋ X is a monovalent alkali metal. - R is a monovalent halide ion. ５１ Y is a divalent organic group. ＋ is a monovalent cation. W is a polymerizable group. R ５２ It is a single bond or a divalent organic group.

[0132] Diaryl sulfoxides and benzoic acid derivatives are reacted in the presence of a strong acid to form sulfonium cations. These are then reacted with alkali metal halides to form a halide salt. The halide salt is then reacted with a salt containing an organic acid anion precursor (a hydroxyl group-containing structure in the scheme) to introduce polymerizable groups, followed by salt exchange. Finally, the mixture is reacted with a polymerizable carboxylic acid to synthesize the desired monomer compound. Other structures can also be synthesized by appropriately changing the starting materials and intermediate components.

[0133] [Structural Unit (II)] Structural unit (II) is a structural unit containing an acid-dissociable group. An "acid-dissociable group" is a hydrogen atom-substituting group such as a carboxyl group, phenolic hydroxyl group, alcoholic hydroxyl group, or sulfo group that dissociates upon the action of an acid. The radiation-sensitive composition exhibits excellent pattern-forming properties because the polymer contains structural unit (II).

[0134] Structural unit (II) is not particularly limited as long as it has an acid-dissociable group, and examples include structural units having a tertiary alkyl ester moiety, structural units having a structure in which the hydrogen atom of a phenolic hydroxyl group is replaced by a tertiary alkyl group, and structural units having an acetal bond. However, from the viewpoint of improving the pattern-forming properties of the radiation-sensitive composition, the structural unit represented by the following formula (3) (hereinafter also referred to as "structural unit (II-1)") is preferred.

[0135]

[0136] In the above formula (3), R １７R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. １８ R is a monovalent substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms. １９ and R ２０ Each of these independently represents either a monovalent substituted or unsubstituted linear hydrocarbon group having 1 to 10 carbon atoms, a monovalent substituted or unsubstituted alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a divalent alicyclic group having 3 to 20 carbon atoms formed by combining these groups with the carbon atoms to which they are bonded. Ｑ teeth, ＊ -COO-, ＊ -L Ｑａ COO- or ＊ -COOL Ｑａ Represents COO-. Ｑａ * is a substituted or unsubstituted alkanediyl group or arenediyl group. １７ This is the bonding site with the carbon atom to which it is bonded.

[0137] The above R １７ From the viewpoint of copolymerization of the monomer that gives the structural unit (II-1), hydrogen atoms and methyl groups are preferred, and methyl groups are more preferred.

[0138] L Ｑａ Examples of alkanediyl groups represented by include methylene groups, ethanediyl groups, 1,3-propanediyl groups, and 2,2-propanediyl groups, which have 1 to 10 carbon atoms. Ｑａ Methylene groups and ethanediyl groups are preferred as the base group.

[0139] L Ｑａ Examples of allenediyl groups represented by include divalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, such as benzenediyl groups and naphthalenediyl groups. Ｑａ A benzenediyl group is preferred as the group.

[0140] L Ｑａ The substituents that the arenediyl group represented by can have include halogen atoms, hydroxyl groups, carboxyl groups, cyano groups, nitro groups, alkyl groups, fluorinated alkyl groups, alkoxycarbonyloxy groups, acyl groups, acyloxy groups, and alkoxy groups.

[0141] The above R １８ As the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (1) above, the monovalent hydrocarbon group having 1 to 20 carbon atoms shown in the polymerizable group of formula (1) above can be suitably adopted.

[0142] The above R １８ Preferably, the hydrocarbon group is a straight-chain or branched-chain saturated hydrocarbon group having 1 to 10 carbon atoms, or an alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0143] The above R １９ and R ２０ The divalent alicyclic groups having 3 to 20 carbon atoms, which are formed by combining these atoms with the carbon atoms to which they are bonded, can preferably be groups obtained by removing one hydrogen atom from the above-mentioned monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms.

[0144] Among these, R １８ R is an alkyl group, alkenyl group, or phenyl group having 1 to 4 carbon atoms. １９ and R ２０ It is preferable that the alicyclic structure formed by combining these elements with the carbon atoms to which they are bonded is a polycyclic or monocyclic cycloalkane structure.

[0145] The above R １８ ~R ２０ The substituents that can be present are L Ｑａ The substituents that the arenediyl group represented by can have can be suitably adopted.

[0146] Examples of structural units (II-1) include the structural units represented by the following formulas (3-1) to (3-15) (hereinafter also referred to as "structural units (II-1-1) to (II-1-15)").

[0147]

[0148]

[0149] In the above equations (3-1) to (3-15), R １７ ~R ２０ This is equivalent to equation (3) above. R Ｌ１１R is a halogen atom, hydroxyl group, carboxyl group, cyano group, nitro group, alkyl group, fluorinated alkyl group, alkoxycarbonyloxy group, acyl group, acyloxy group, or alkoxy group. i and j are each independently integers from 1 to 4. k and l are 0 or 1. 3a are each independently integers from 0 to 3. If 3a is 2 or more, multiple R Ｌ１１ They are either identical or different from each other. a4 is an integer between 1 and 3.

[0150] i and j are preferably 1. １８ Preferred groups include methyl, ethyl, isopropyl, t-butyl, cyclopentyl, ethenyl, phenyl, and iodophenyl groups. １９ and R ２０ Preferably, the group is a methyl group, an ethyl group, or an isopropyl group. Ｌ１１ By employing an iodine atom, an iodine group can be suitably introduced into the structural unit (II).

[0151] Furthermore, the polymer may contain structural units represented by the following formulas (1f) to (2f) as structural units (II).

[0152]

[0153] In the above equations (1f) to (2f), R αｆ Each of these is independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. βｆ Each of these is independently a hydrogen atom or a chain-like alkyl group having 1 to 5 carbon atoms. １ is an integer between 1 and 4.

[0154] The above R βｆ Preferably, it is a hydrogen atom, a methyl group, or an ethyl group. １ 1 or 2 is preferred.

[0155] The lower limit of the content of structural unit (II) (total content if multiple types are included) is preferably 10 mol%, more preferably 20 mol%, and even more preferably 30 mol%, relative to the total structural units constituting the base polymer. The upper limit of the above content is preferably 80 mol%, more preferably 70 mol%, and even more preferably 60 mol%. By setting the content of structural unit (II) within the above range, the pattern-forming properties of the radiation-sensitive composition can be further improved.

[0156] [Structural Unit (III)] Structural unit (III) is a structural unit having a phenolic hydroxyl group. Structural unit (III) contributes to improved etching resistance and improved difference in developer solubility between exposed and unexposed areas (dissolution contrast). It can be suitably applied to pattern formation using exposure with radiation of wavelength 50 nm or less, such as KrF excimer lasers, electron beams, and EUV. In this case, it is preferable that the polymer has structural unit (II) along with structural unit (III).

[0157] The structural unit having a phenolic hydroxyl group is preferably represented by the following formula (4).

[0158] (In the above formula (4), R β L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ＣＡ This is a single bond, -COO- ＊ Or -O-. * indicates a bond on the aromatic ring side. R １０２ R is a halogen atom, cyano group, nitro group, alkyl group, alkoxycarbonyl group, acyl group, or acyloxy group. １０２ If multiple R １０２ They are either identical or different from each other. ３ m is an integer between 0 and 2. ３ m is an integer from 1 to 8. ４ Each of these is an independent integer between 0 and 8, where 1 ≤ m. ３ +m ４ ≤ 2n ３ (Saves +5.)

[0159] The above R βFrom the viewpoint of copolymerization of the monomer that gives structural unit (III), it is preferable that the atom is a hydrogen atom or a methyl group.

[0160] L ＣＡ For example, a single bond or -COO- ＊ It is preferable.

[0161] R １０２ In this case, an iodine atom is preferred as the halogen atom.

[0162] The above n ３ 0 or 1 is more preferable, and 0 is even more preferable.

[0163] The above m ３ Preferably, the integer is between 1 and 3, and more preferably 1 or 2.

[0164] The above m ４ Preferably, the integer is between 0 and 3, and more preferably between 0 and 2.

[0165] For polymers used for exposure with KrF excimer lasers or radiation with wavelengths of 50 nm or less, the lower limit of the content of structural unit (III) in the total structural units constituting the base polymer (the total content if multiple types are included) is preferably 10 mol%, and more preferably 20 mol%. The upper limit of the above content is preferably 60 mol%, and more preferably 50 mol%.

[0166] [Structural Unit (IV)] Structural Unit (IV) is a structural unit comprising at least one selected from the group consisting of lactone structures, cyclic carbonate structures, and sultone structures. By further comprising Structural Unit (IV), the solubility of the base polymer in the developer can be adjusted, and as a result, the radiation-sensitive composition can improve lithography performance such as resolution. Furthermore, the adhesion between the resist pattern formed from the base polymer and the substrate can be improved.

[0167] Examples of structural units (IV) include those represented by the following formulas (T-1) to (T-11).

[0168]

[0169] In the above formula, R Ｌ１R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ｌ２ ~R Ｌ５ These are, independently, a hydrogen atom, a C1-C4 alkyl group, a cyano group, a trifluoromethyl group, a methoxy group, a methoxycarbonyl group, a hydroxyl group, a hydroxymethyl group, and a dimethylamino group. Ｌ４ and R Ｌ５ These may be divalent alicyclic groups having 3 to 8 carbon atoms, which can be combined with each other and bonded together with the carbon atoms. ２ is a single bond or a divalent linking group. X is an oxygen atom or a methylene group. k is an integer from 0 to 3. m is an integer from 1 to 3.

[0170] The above R Ｌ４ and R Ｌ５ When these are combined with each other, the divalent alicyclic group having 3 to 8 carbon atoms, formed together with the carbon atoms to which they are bonded, is R in formula (3) above. １９ and R ２０ Examples include divalent alicyclic groups with 3 to 20 carbon atoms, where these groups are combined with each other and formed together with the carbon atoms to which they are bonded, specifically groups with 3 to 8 carbon atoms. One or more hydrogen atoms on these alicyclic groups may be substituted with hydroxyl groups.

[0171] The above L ２ Examples of divalent linking groups represented by include divalent linear or branched hydrocarbon groups having 1 to 10 carbon atoms, divalent alicyclic hydrocarbon groups having 4 to 12 carbon atoms, or groups composed of one or more of these hydrocarbon groups and at least one of the groups -CO-, -O-, -NH-, and -S-.

[0172] Among these, structural units (IV) are preferably those containing a lactone structure, more preferably those containing a γ-butyrolactone structure or a norbornane lactone structure, and even more preferably those derived from γ-butyrolactone-yl-(meth)acrylate or norbornane lactone-yl(meth)acrylate.

[0173] When the base polymer contains structural unit (IV), the lower limit of the content of structural unit (IV) in the total structural units constituting the base polymer (the total content if multiple types are included) is preferably 2 mol%, more preferably 5 mol%, and even more preferably 8 mol%. The upper limit of the content is preferably 80 mol%, more preferably 70 mol%, and even more preferably 60 mol%. By setting the content of structural unit (II) within the above range, the radiation-sensitive composition can further improve lithography performance such as resolution and the adhesion of the formed resist pattern to the substrate.

[0174] [Structural Unit (V)] Structural unit (V) is a structural unit containing a polar group (excluding those corresponding to structural units (I) to (IV)). The base polymer can have its solubility in the developer adjusted by further containing structural unit (V), and as a result, the lithographic performance such as resolution of the radiation-sensitive composition can be improved. Examples of the above polar group include a hydroxyl group, a carboxyl group, a cyano group, a nitro group, a sulfonamide group, etc. Among these, a hydroxyl group and a carboxyl group are preferred, and a hydroxyl group is more preferred.

[0175] Examples of structural units (V) include structural units represented by the following formula.

[0176]

[0177]

[0178] In the above formula, R Ｋ This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0179] When the base polymer has a structural unit (V) having the polar group, the lower limit of the content of the structural unit (V) in the total structural units constituting the base polymer (the total content if multiple types are included) is preferably 1 mol%, more preferably 2 mol%, and still preferably 3 mol%. The upper limit of the content is preferably 20 mol%, more preferably 10 mol%, and still preferably 8 mol%. By setting the content of structural unit (V) within the above range, the lithographic performance, such as resolution, of the radiation-sensitive composition can be further improved.

[0180] [Other structural units] The base polymer may also contain structural units other than those listed above, such as structural units having an alicyclic structure represented by the following formula (6) (hereinafter also referred to as "structural unit (VI)"). (In the above formula (6), R １α R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ２α (It is a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.)

[0181] In the above formula (6), R ２α As a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the above formula (1), R ２ A monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms can be suitably used in this material.

[0182] When the base polymer contains structural unit (VI), the lower limit of the content of structural unit (VI) is preferably 2 mol%, more preferably 5 mol%, and even more preferably 8 mol%, relative to the total structural units constituting the base polymer. The upper limit of the above content is preferably 30 mol%, more preferably 20 mol%, and even more preferably 15 mol%.

[0183] (Method for synthesizing base polymers) Base polymers can be synthesized, for example, by polymerizing monomers that give each structural unit in a suitable solvent using a radical polymerization initiator or the like.

[0184] Examples of the radical polymerization initiators mentioned above include azo-based radical initiators such as azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and dimethyl 2,2'-azobisisobutyrate; and peroxide-based radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, and cumene hydroperoxide. Among these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferred. These radical initiators can be used individually or in combination of two or more.

[0185] Solvents used in the above polymerization include, for example, alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane; cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, and norbornane; aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and cumene; halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, and chlorobenzene; saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, isobutyl acetate, and methyl propionate; polyhydric alcohol partial ether acetate solvents such as diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate; and ketones such as acetone, methyl ethyl ketone, 2-butanone, 4-methyl-2-pentanone, 2-heptanone, and cyclohexanone. Examples include ethers such as tetrahydrofuran, dimethoxyethanes, diethoxyethanes, and 1,4-dioxanes; alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 4-methyl-2-pentanol, and 1-methoxy-2-propanol (propylene glycol monomethyl ether); and lactones such as γ-butyrolactone. The solvents used in these polymerizations may be used alone or in combination of two or more.

[0186] The reaction temperature in the polymerization described above is usually 40°C to 150°C, with 50°C to 120°C being preferred. The reaction time is usually 1 hour to 48 hours, with 1 hour to 24 hours being preferred.

[0187] The molecular weight of the base polymer is not particularly limited, but the lower limit of the polystyrene-equivalent weight-average molecular weight (Mw) determined by gel permeation chromatography (GPC) is preferably 3,000, more preferably 4,000, and even more preferably 5,000. The upper limit of Mw is preferably 30,000, more preferably 20,000, and even more preferably 14,000. By keeping the Mw of the base polymer within the above range, good heat resistance and developability can be obtained in the resulting resist film.

[0188] The ratio of Mw to the polystyrene-equivalent number-average molecular weight (Mn) of the base polymer (Mw / Mn) determined by GPC is usually between 1 and 5, preferably between 1 and 3, and more preferably between 1 and 2.

[0189] In this specification, the Mw and Mn values ​​of polymers are measured using gel permeation chromatography (GPC) under the following conditions.

[0190] GPC columns: 2 x G2000HXL, 1 x G3000HXL, 1 x G4000HXL (all manufactured by Tosoh) Column temperature: 40°C Elution solvent: Tetrahydrofuran Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Detector: Differential refractometer Standard material: Monodisperse polystyrene

[0191] The base polymer content is preferably 60% by mass or more, more preferably 65% ​​by mass or more, and even more preferably 70% by mass or more, based on the total solid content of the radiation-sensitive composition.

[0192] (Other Polymers) The radiation-sensitive composition of this embodiment may also contain, as other polymers, a polymer with a higher mass content of fluorine atoms than the base polymer (hereinafter also referred to as a "high-fluorine content polymer"). When the radiation-sensitive composition contains a high-fluorine content polymer, it can be unevenly distributed on the surface of the resist film relative to the base polymer, and as a result, it is possible to improve the water repellency of the surface of the resist film during immersion exposure, or to modify the surface of the resist film and control the distribution of the composition within the film during EUV exposure.

[0193] High-fluorine-content polymers may have, for example, a structural unit represented by the following formula (5) (hereinafter also referred to as "structural unit (VII)").

[0194]

[0195] In the above formula (5), R １３ This is a hydrogen atom, a methyl group, or a trifluoromethyl group. Ｌ It consists of a single bond, an alkanediyl group with 1 to 5 carbon atoms, an oxygen atom, a sulfur atom, -COO-, and -SO ２ ONH-, -CONH-, -OCONH-, or a combination thereof. １４ This is a monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0196] The above R １３ From the viewpoint of copolymerization of monomers that give structural unit (VII), hydrogen atoms and methyl groups are preferred, and methyl groups are more preferred.

[0197] The above G Ｌ From the viewpoint of copolymerization of monomers that provide structural unit (VII), single bonds and -COO- are preferred, and -COO- is more preferred.

[0198] The above R １４ Examples of monovalent fluorinated linear hydrocarbon groups having 1 to 20 carbon atoms, represented by , include those in which some or all of the hydrogen atoms in a linear or branched alkyl group having 1 to 20 carbon atoms are substituted with fluorine atoms.

[0199] The above R １４Examples of monovalent fluorinated alicyclic hydrocarbon groups having 3 to 20 carbon atoms, represented by , include those in which some or all of the hydrogen atoms in a monocyclic or polycyclic hydrocarbon group having 3 to 20 carbon atoms are substituted with fluorine atoms.

[0200] The above R １４ Preferably, the group is a fluorinated chain hydrocarbon group, more preferably a fluorinated alkyl group, and even more preferably a 2,2,2-trifluoroethyl group, a 2,2,3,3,3-pentafluoropropyl group, a 1,1,1,3,3,3-hexafluoropropyl-2-yl group, and a 5,5,5-trifluoro-1,1-diethylpentyl group.

[0201] When a high-fluorine-content polymer has structural unit (VII), the lower limit of the content of structural unit (VII) is preferably 50 mol%, more preferably 60 mol%, and even more preferably 70 mol%, relative to the total structural units constituting the high-fluorine-content polymer. The upper limit of the above content is preferably 95 mol%, more preferably 90 mol%, and even more preferably 85 mol%. By setting the content of structural unit (VII) within the above range, the mass content of fluorine atoms in the high-fluorine-content polymer can be more appropriately adjusted, further promoting the uneven distribution on the surface of the resist film, and as a result, the water repellency of the resist film during immersion exposure can be further improved.

[0202] High-fluorine polymers may have a fluorine atom-containing structural unit represented by the following formula (f-2) (hereinafter also referred to as structural unit (VIII)) together with or in place of structural unit (VII). The presence of structural unit (f-2) in high-fluorine polymers improves solubility in alkaline developers and suppresses the occurrence of development defects.

[0203]

[0204] Structural units (VIII) can be broadly classified into two types: (x) those having an alkali-soluble group, and (y) those having a group that dissociates under the action of alkali, increasing its solubility in an alkaline developer (hereinafter also simply referred to as an "alkali-dissociable group"). In both (x) and (y), in the above formula (f-2), R ＣR is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ｄ R is a single bond, a (s+1) valent hydrocarbon group with 1 to 20 carbon atoms, and this hydrocarbon group Ｅ At the end of the side are an oxygen atom, a sulfur atom, and -NR ｄｄ -A structure to which a carbonyl group, -COO-, -OCO-, or -CONH- is bonded, or a structure in which some of the hydrogen atoms of this hydrocarbon group are substituted by an organic group having a heteroatom. ｄｄ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. s is an integer from 1 to 3.

[0205] If structural unit (VIII) has (x) an alkali-soluble group, R Ｆ A is a hydrogen atom, １ The oxygen atom is -COO-* or -SO ２ It is O-*. * is R Ｆ This indicates the binding site. １ This is a single bond, a hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated hydrocarbon group. １ If is an oxygen atom, W １ is A １ It is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group at the carbon atom to which it is bonded. Ｅ is a single bond or a divalent organic group having 1 to 20 carbon atoms. When s is 2 or 3, multiple R Ｅ , W １ A １ and R Ｆ These may be the same or different. The structural unit (VIII) having (x) an alkali-soluble group increases its affinity for alkaline developers and suppresses development defects. A is an example of a structural unit (VIII) having (x) an alkali-soluble group. １ is an oxygen atom and W １ It is particularly preferable that the group is a 1,1,1,3,3,3-hexafluoro-2,2-methanediyl group.

[0206] If structural unit (VIII) has an alkali-dissociable group (y), R Ｆ A is a monovalent organic group having 1 to 30 carbon atoms. １ is an oxygen atom, -NR ａａ-, -COO-*, -OCO-*, or -SO ２ It is O-*. ａａ * is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. Ｆ This indicates the binding site. １ R is a single bond or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. Ｅ A is a single bond or a divalent organic group having 1 to 20 carbon atoms. １ -COO-*, -OCO-*, or -SO ２ If it is O-*, then W １ or R Ｆ is A １ It has a fluorine atom on the carbon atom bonded to it or on an adjacent carbon atom. １ If is an oxygen atom, W １ , R Ｅ It is a single bond, R Ｄ R is a hydrocarbon group having 1 to 20 carbon atoms. Ｅ It is a structure in which a carbonyl group is bonded to the terminal end, R Ｆ is an organic group having a fluorine atom. When s is 2 or 3, multiple R Ｅ , W １ A １ and R Ｆ These may be the same or different. The presence of a (y) alkali-dissociable group in structural unit (VIII) causes the resist film surface to change from hydrophobic to hydrophilic during the alkali development process. As a result, the affinity for the developer is significantly increased, and development defects can be suppressed more efficiently. Examples of structural unit (VIII) having a (y) alkali-dissociable group include A １ is -COO-*, R Ｆ Or W １ Alternatively, it is particularly preferable that both of these contain fluorine atoms.

[0207] R Ｃ From the viewpoint of copolymerizability of monomers that give structural unit (VIII), hydrogen atoms and methyl groups are preferred, and methyl groups are more preferred.

[0208] When a high-fluorine-content polymer has structural unit (VIII), the content of structural unit (VIII) is preferably 20 mol%, more preferably 30 mol%, and even more preferably 40 mol%, relative to the total structural units constituting the high-fluorine-content polymer. Furthermore, the upper limit of the above content is preferably 80 mol%, more preferably 70 mol%, and even more preferably 60 mol%. By setting the content of structural unit (VI) within the above range, it is possible to improve the water repellency of the resist film during immersion exposure and improve solubility in alkaline developers, thereby suppressing the occurrence of development defects.

[0209] [Other structural units] High-fluorine polymers may, if necessary, include structural units other than those listed above, such as structural unit (I-2), structural unit (II), and structural unit (VI) in the base polymer.

[0210] When a high-fluorine-content polymer contains structural unit (I-2), the content of structural unit (I-2) is preferably 1 mol%, and more preferably 2 mol%, relative to the total structural units constituting the high-fluorine-content polymer. Furthermore, the upper limit of the above content is preferably 20 mol%, and more preferably 10 mol%.

[0211] When a high-fluorine-content polymer contains structural unit (II), the content of structural unit (II) is preferably 20 mol%, and more preferably 30 mol%, relative to the total structural units constituting the high-fluorine-content polymer. Furthermore, the upper limit of the above content is preferably 60 mol%, and more preferably 50 mol%.

[0212] When a high-fluorine-content polymer contains structural units (VI), the content of structural units (VI) is preferably 20 mol%, and more preferably 30 mol%, relative to the total structural units constituting the high-fluorine-content polymer. Furthermore, the upper limit of the above content is preferably 60 mol%, and more preferably 50 mol%.

[0213] The lower limit of Mw for the high-fluorine-content polymer is preferably 4,000, more preferably 5,000, and even more preferably 6,000. The upper limit of Mw is preferably 20,000, more preferably 10,000, and even more preferably 8,000.

[0214] The lower limit of Mw / Mn of the high-fluorine content polymer is usually 1, and more preferably 1.1. The upper limit of Mw / Mn is usually 5, preferably 3, and more preferably 2.

[0215] When the radiation-sensitive composition contains a high-fluorine content polymer, the lower limit of the content of the high-fluorine content polymer is preferably 0.5 parts by mass, more preferably 1 part by mass, and still more preferably 1.5 parts by mass with respect to 100 parts by mass of the base polymer. The upper limit of the content is preferably 15 parts by mass, more preferably 10 parts by mass, and still more preferably 8 parts by mass.

[0216] By setting the content of the high-fluorine content polymer within the above range, the high-fluorine content polymer can be more effectively unevenly distributed on the surface layer of the resist film. As a result, the water repellency of the surface of the resist film during immersion exposure can be enhanced, or surface modification of the resist film and control of the distribution of the composition within the film during EUV exposure can be achieved. The radiation-sensitive composition may contain one or more high-fluorine content polymers.

[0217] (Synthesis method of high-fluorine content polymer) The high-fluorine content polymer can be synthesized by the same method as the synthesis method of the above-described base polymer.

[0218] (Solvent) The radiation-sensitive composition according to the present embodiment contains a solvent. The solvent is not particularly limited as long as it can dissolve or disperse at least the base polymer and optional components that may be contained as desired.

[0219] Examples of the solvent include alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, hydrocarbon solvents, and the like.

[0220] Examples of alcohol-based solvents include monoalcohol solvents having 1 to 18 carbon atoms, such as isopropanol, 4-methyl-2-pentanol, n-hexanol, 2-ethylhexanol, furfuryl alcohol, cyclohexanol, 3,3,5-trimethylcyclohexanol, and diacetone alcohol; polyhydric alcohol solvents having 2 to 18 carbon atoms, such as ethylene glycol, 1,2-propylene glycol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol; and polyhydric alcohol partial ether solvents, such as 3-methoxybutanol and 1-methoxy-2-propanol (propylene glycol monomethyl ether), which are obtained by etherifying some of the hydroxyl groups in the above-mentioned polyhydric alcohol solvents. In this embodiment, alcohol acid ester solvents such as methyl lactate, ethyl lactate, propyl lactate, butyl lactate, methyl 2-hydroxyisobutyrate, isopropyl 2-hydroxyisobutyrate, isobutyl 2-hydroxyisobutyrate, and n-butyl 2-hydroxyisobutyrate are also included in the alcohol-based solvents.

[0221] Examples of ether-based solvents include dialkyl ether solvents such as diethyl ether, dipropyl ether, and dibutyl ether; cyclic ether solvents such as tetrahydrofuran and tetrahydropyran; aromatic ring-containing ether solvents such as diphenyl ether and anisole (methylphenyl ether); and polyhydric alcohol ether solvents obtained by etherifying the hydroxyl groups of the above-mentioned polyhydric alcohol solvents.

[0222] Examples of ketone solvents include: linear ketone solvents such as acetone, butanone, and methyl isobutyl ketone; cyclic ketone solvents such as cyclopentanone, cyclohexanone, and methylcyclohexanone; and 2,4-pentanedione, acetonylacetone, and acetophenone.

[0223] Examples of amide solvents include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; and chain-like amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0224] Examples of ester solvents include monocarboxylic acid ester solvents such as n-butyl acetate; polyhydric alcohol partial ether acetate solvents such as diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate; lactone solvents such as γ-butyrolactone and valerolactone; carbonate solvents such as diethyl carbonate, ethylene carbonate, and propylene carbonate; and polyhydric carboxylic acid diester solvents such as propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoethyl acetate, and diethyl phthalate.

[0225] Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; and aromatic hydrocarbon solvents such as benzene, toluene, diisopropylbenzene, and n-amylnaphthalene.

[0226] Among these, alcohol-based solvents, ester-based solvents, and ketone-based solvents are preferred, alcoholic acid ester-based solvents, C1-C18 monoalcohol-based solvents, polyhydric alcohol partial ether acetate-based solvents, polyhydric alcohol partial ether-based solvents, and lactone-based solvents are more preferred, and methyl 2-hydroxyisobutyrate, diacetone alcohol, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, and γ-butyrolactone are even more preferred. The radiation-sensitive composition may contain one or more solvents.

[0227] (Radiation-sensitive acid generator) The radiation-sensitive composition may contain a radiation-sensitive acid generator. The radiation-sensitive acid generator contains an organic acid anion and an onium cation, forming an onium salt structure. This onium salt structure differs from the onium salt structure in structural unit (I-1) in that it does not have polymerizable groups. The radiation-sensitive acid generator is a component that generates acid upon exposure. The acid generated upon exposure has the function of dissociating the acid-dissociable groups of the base polymer and generating carboxyl groups, etc. The radiation-sensitive acid generator has a form in which the onium salt structure exists alone as a low molecular weight compound (liberated from the polymer), and differs from structural unit (I-1) in the above base polymer in which the organic acid anion or sulfonium cation is bonded (covalently bonded) to the main chain as a side chain structure of the base polymer.

[0228] The structural formulas and specific examples of the organic acid anion and onium cation possessed by the radiation-sensitive acid generator can suitably employ structures other than the polymerizable group in the monomer compound that gives the structural unit (I-1) of the base polymer.

[0229] The radiation-sensitive acid generator may be used alone or in combination of two or more types. The content of the radiation-sensitive acid generator (total in the case of multiple types) can be determined by whether or not the base polymer has structural unit (I-1). If the base polymer has structural unit (I-1), the lower limit of the radiation-sensitive acid generator content may be 0 parts by mass (i.e., no radiation-sensitive acid generator), 1 part by mass, or 3 parts by mass. The upper limit of the above content is preferably 15 parts by mass, more preferably 10 parts by mass, and still more preferably 8 parts by mass. If the base polymer does not have structural unit (I-1), the lower limit of the radiation-sensitive acid generator content is preferably 5 parts by mass, more preferably 10 parts by mass, and still more preferably 15 parts by mass. The upper limit of the above content is preferably 80 parts by mass, more preferably 70 parts by mass, and still more preferably 60 parts by mass. This allows the above-mentioned resist properties to be fully exhibited during pattern formation.

[0230] <Acid Diffusion Control Agent> The radiation-sensitive composition may contain an acid diffusion control agent. The acid diffusion control agent contains an onium salt structure formed by an organic acid anion and an onium cation. This onium salt structure differs from the onium salt structure in structural unit (I-2) in that it does not have polymerizable groups. Under pattern-forming conditions using the radiation-sensitive composition, the acid diffusion control agent has the function of substantially preventing the dissociation of the acid-dissociable groups of the base polymer and suppressing the diffusion of acid generated from the radiation-sensitive acid generator in the unexposed areas by salt exchange. In other words, the acid diffusion control agent can be said to generate an acid with a higher pKa than the radiation-sensitive acid-generating structure or the acid generated from the radiation-sensitive acid generator upon irradiation with radiation. The acid diffusion control agent has a form in which the onium salt structure exists alone as a low molecular weight compound (liberated from the polymer), and differs from structural unit (I-2) in the base polymer in which an organic acid anion or sulfonium cation is bonded (covalently bonded) to the main chain as a side chain structure of the base polymer.

[0231] By including the above-mentioned acid diffusion control agent in the radiation-sensitive composition, acid diffusion in unexposed areas can be suppressed, enabling the formation of a resist pattern with superior roughness suppression, resolution, and development contrast.

[0232] The structural formulas and specific examples of the organic acid anion and onium cation possessed by the acid diffusion control agent can suitably employ structures other than the polymerizable group in the monomer compound that gives the structural unit (I-2) of the base polymer.

[0233] The acid diffusion control agent may be used alone or in combination of two or more types. The content of the acid diffusion control agent (total in the case of multiple types) can be determined by whether or not the base polymer has structural units (I-2). If the base polymer has structural units (I-2), the lower limit of the acid diffusion control agent content may be 0 parts by mass (i.e., no acid diffusion control agent), 1 part by mass, or 3 parts by mass. The upper limit of the above content is preferably 15 parts by mass, more preferably 10 parts by mass, and still more preferably 8 parts by mass. If the base polymer does not have structural units (I-2), the lower limit of the acid diffusion control agent content is preferably 3 parts by mass, more preferably 6 parts by mass, and still more preferably 10 parts by mass. The upper limit of the above content is preferably 60 parts by mass, more preferably 50 parts by mass, and still more preferably 40 parts by mass. This allows the above-mentioned resist properties to be fully exhibited during pattern formation.

[0234] (Other optional components) The above-mentioned radiation-sensitive composition may contain other optional components in addition to the components listed above. Examples of these other optional components include crosslinking agents, localization promoters, surfactants, alicyclic skeleton-containing compounds, sensitizers, etc. These other optional components may be used individually or in combination of two or more types.

[0235] <Method for preparing a radiation-sensitive composition> The above radiation-sensitive composition can be prepared by mixing, for example, a polymer, and optionally a high-fluorine-content polymer, and a solvent in a predetermined ratio. After mixing, the above radiation-sensitive composition is preferably filtered using, for example, a filter with a pore size of about 0.05 μm to 0.40 μm. The solid content concentration of the above radiation-sensitive composition is usually 0.1% to 50% by mass, preferably 0.5% to 30% by mass, and more preferably 1% to 20% by mass.

[0236] <Pattern Forming Method> A pattern forming method according to one embodiment of the present invention includes a step (1) of applying the above-mentioned radiation-sensitive composition directly or indirectly to a substrate to form a resist film (hereinafter also referred to as the "resist film forming step"), a step (2) of exposing the resist film (hereinafter also referred to as the "exposure step"), and a step (3) of developing the exposed resist film with a developer (hereinafter also referred to as the "development step").

[0237] According to the pattern formation method described above, since the radiation-sensitive composition that exhibits excellent sensitivity, CDU, LWR, MEEF, development defect suppression, and pattern rectangularity is used during pattern formation, high-quality resist patterns can be efficiently formed. The following describes each step.

[0238] [Resist Film Formation Process] In this process (step (1) above), a resist film is formed using the radiation-sensitive composition described above. Examples of substrates for forming this resist film include conventionally known materials such as silicon wafers, silicon dioxide wafers, and aluminum-coated wafers. Alternatively, an organic or inorganic anti-reflective film, such as those disclosed in Japanese Patent Publication No. 6-12452 or Japanese Patent Publication No. 59-93448, may be formed on the substrate. Examples of coating methods include spin coating, casting, and roll coating. After coating, pre-baking (PB) may be performed as needed to volatilize the solvent in the coating film. The PB temperature is usually 60°C to 160°C, with 80°C to 140°C being preferred. The PB time is usually 5 seconds to 600 seconds, with 10 seconds to 300 seconds being preferred.

[0239] The lower limit of the thickness of the formed resist film is preferably 10 nm, more preferably 15 nm, and even more preferably 20 nm. The upper limit of the thickness is preferably 500 nm, more preferably 350 nm, and even more preferably 280 nm.

[0240] When performing immersion exposure, regardless of the presence or absence of water-repellent polymer additives such as the high-fluorine-content polymer in the above-mentioned radiation-sensitive composition, an immersion-insoluble protective film may be provided on the formed resist film to avoid direct contact between the immersion liquid and the resist film. As the immersion-protective film, either a solvent-peelable protective film that is peeled off with a solvent before the development process (see, for example, Japanese Patent Application Publication No. 2006-227632) or a developer-peelable protective film that is peeled off simultaneously with development in the development process (see, for example, Japanese Patent Application Publication Nos. WO2005-069076 and WO2006-035790) may be used. However, from the viewpoint of throughput, it is preferable to use a developer-peelable immersion-protective film.

[0241] [Exposure Process] In this process (process (2) above), the resist film formed in the resist film formation process, which is process (1) above, is exposed by irradiating it with radiation through a photomask (and, in some cases, through an immersion liquid such as water). The radiation used for exposure can be electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV (extreme ultraviolet light), X-rays, and gamma rays, depending on the line width of the desired pattern; for example, electron beams and charged particle beams such as alpha rays. Among these, far ultraviolet light, electron beams, and EUV are preferred, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), electron beams, and EUV are more preferred, and electron beams and EUV with wavelengths of 50 nm or less, which are positioned as next-generation exposure technologies, are even more preferred.

[0242] When exposure is performed by immersion lithography, the immersion liquid used can be, for example, water or a fluorine-based inert liquid. The immersion liquid is preferably transparent to the exposure wavelength and has the smallest possible temperature coefficient of refractive index to minimize distortion of the optical image projected onto the film. In particular, when the exposure light source is ArF excimer laser light (wavelength 193 nm), in addition to the above considerations, water is preferred due to its availability and ease of handling. When water is used, a small amount of an additive that reduces the surface tension of the water and increases its surfactant properties may be added. This additive is preferably one that does not dissolve the resist film on the wafer and has negligible effect on the optical coating on the underside of the lens. Distilled water is preferred as the water used.

[0243] After the exposure described above, it is preferable to perform a post-exposure bake (PEB) to promote the dissociation of acid-dissociable groups of polymers, etc., in the exposed portion of the resist film by the acid generated from the structural unit (I-1) or the radiation-sensitive acid generator due to the exposure. This PEB creates a difference in solubility in the developer between the exposed and unexposed portions. The PEB temperature is usually 50°C to 180°C, with 80°C to 130°C being preferred. The PEB time is usually 5 seconds to 600 seconds, with 10 seconds to 300 seconds being preferred.

[0244] [Development Process] In this process (step (3) above), the resist film exposed in the exposure process, which is step (2) above, is developed. This allows a predetermined resist pattern to be formed. After development, it is common to wash with a rinsing solution such as water or alcohol and then dry it.

[0245] Examples of developers used in the above development process include, in the case of alkaline development, an alkaline aqueous solution containing at least one alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, and 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, an aqueous TMAH solution is preferred, and a 2.38% by mass aqueous TMAH solution is more preferred.

[0246] Furthermore, in the case of organic solvent development, examples of organic solvents include hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents, etc., or solvents containing organic solvents. Examples of the above organic solvents include one or more of the solvents listed above as solvents for the radiation-sensitive composition. Among these, ether solvents, ester solvents, and ketone solvents are preferred. As for ether solvents, glycol ether solvents are preferred, and ethylene glycol monomethyl ether and propylene glycol monomethyl ether are more preferred. As for ester solvents, acetate ester solvents are preferred, and n-butyl acetate and amyl acetate are more preferred. As for ketone solvents, chain ketones are preferred, and 2-heptanone is more preferred. The content of organic solvents in the developer is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more. Examples of components other than organic solvents in the developer include water and silicone oil.

[0247] As mentioned above, either an alkaline developer or an organic solvent developer may be used as the developer. The appropriate developer can be selected depending on whether a positive or negative pattern is desired.

[0248] Examples of development methods include immersing the substrate in a tank filled with developer solution for a certain period of time (dip method), developing by puddling the developer solution onto the substrate surface using surface tension and leaving it still for a certain period of time (paddle method), spraying the developer solution onto the substrate surface (spray method), and continuously dispensing the developer solution while scanning a developer solution dispensing nozzle at a constant speed onto a substrate rotating at a constant speed (dynamic dispensing method).

[0249] <Polymer> The polymer in question is a polymer that contains structural unit (I) derived from the compound represented by the following formula (1). (In formula (1), R １ A is a monovalent organic group having 1 to 40 carbon atoms. However, A - ga-SO ３ - If R １ A is a monovalent organic group with 3 to 40 carbon atoms that includes a cyclic structure. - is, -SO ３ - ,-COO - or -N - -SO ２ -R Ｘ That is. R Ｘ R is a monovalent organic group having 1 to 20 carbon atoms. ２ R is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. ３ R is a hydroxyl group or a monovalent organic group having 1 to 20 carbon atoms. ４ and R ５ Each of these is independently a monovalent organic group having 1 to 20 carbon atoms, or R ４ and R ５ These can be combined to form a ring structure with 4 to 12 carbon atoms, along with the sulfur atoms to which they are bonded. ６ R is a halogen atom, hydroxyl group, nitro group, amino group, carboxyl group, cyano group, or a monovalent organic group having 1 to 20 carbon atoms. ６ If multiple R ６ They are either identical or different from each other. However, R １ ~R ６Any one of them has one polymerizable group. m is 0 or 1. When m is 1, R ３ -CO- and R ２ -O- are both bonded to the 6-membered ring structure to which the sulfur atom in the above formula (1) is bonded. n is an integer from 0 to 4. )

[0250] As such a polymer, the polymer (base polymer) in the above radiation-sensitive composition can be preferably employed.

[0251] <Compound> The compound is a compound represented by the following formula (1). (In formula (1), １ R is a monovalent organic group having 1 to 40 carbon atoms. However, when A - is -SO ３ - , R １ is a monovalent organic group having 3 to 40 carbon atoms including a cyclic structure. A - is -SO ３ - , -COO - or -N - -SO ２ -R Ｘ . R Ｘ is a monovalent organic group having 1 to 20 carbon atoms. R ２ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. R ３ is a hydroxy group or a monovalent organic group having 1 to 20 carbon atoms. R ４ and R ５ are each independently a monovalent organic group having 1 to 20 carbon atoms, or R ４ and R ５ are combined with each other and represent a ring structure having 4 to 12 carbon atoms formed together with the sulfur atom to which they are bonded. R ６ is a halogen atom, a hydroxy group, a nitro group, an amino group, a carboxy group, a cyano group or a monovalent organic group having 1 to 20 carbon atoms. When there are a plurality of R ６ , the plurality of R ６ are the same as or different from each other. However, R １ to R ６One of them has one polymerizable group. m is 0 or 1. If m is 1, R ３ -CO- and R ２ Both -O- atoms bond to the six-membered ring structure to which the sulfur atom in formula (1) above is bonded. (n is an integer from 0 to 4.)

[0252] Suitable examples of such compounds include monomer compounds that provide structural unit (I) in the polymer (base polymer) of the above-mentioned radiation-sensitive composition.

[0253] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. The methods for measuring various physical properties are shown below.

[0254] [Weight-average molecular weight (Mw) and number-average molecular weight (Mn)] The Mw and Mn of the polymer were measured under the conditions described above. The degree of dispersion (Mw / Mn) was calculated from the measured results of Mw and Mn.

[0255] [ １３ [C-NMR analysis] Polymer １３ C-NMR analysis was performed using a nuclear magnetic resonance spectrometer (JEOL Ltd.'s "JNM-Delta400").

[0256] <Synthesis of Compound (Monomer)> [Example A1] (Synthesis of Monomer (A-1)) Compound (A-1) was synthesized according to the following synthesis scheme.

[0257]

[0258] In the reaction vessel, combine 20.0 mmol of 4,4'-sulfinylbis(fluorobenzene), 40.0 mmol of tert-butyl-2-methoxybenzoate, and trifluorosulfonic anhydride (Tf ２ 30.0 mmol of O) and 50 g of dichloromethane were added and the mixture was stirred at -78°C for 12 hours. Then, saturated sodium bicarbonate aqueous solution was added to the reaction solution to terminate the reaction, and dichloromethane was added for extraction, separating the organic layer. The obtained organic layer was washed with saturated sodium chloride aqueous solution, and then with water. After drying over sodium sulfate, the solvent was removed by distillation, and the compound (A-1-a) was obtained in good yield by purification by column chromatography.

[0259] To the above compound (A-1-a), 50 g of 1 M aqueous sodium iodide solution and 50 g of dichloromethane were added and the mixture was stirred at 50°C for 12 hours. Then, dichloromethane was added to the reaction solution for extraction, and the organic layer was separated. By distilling off the solvent from the resulting organic layer, compound (A-1-b) was obtained in good yield.

[0260] To the above compound (A-1-b), 20.0 mmol of compound (A-1-c), 50 g of dichloromethane, and 50 g of water were added and the mixture was stirred at room temperature for 4 hours. Dichloromethane was added to the reaction mixture and extracted, and the organic layer was separated. The obtained organic layer was dried over sodium sulfate, and the solvent was removed by distillation to obtain compound (A-1-d) represented by the above formula (A-1-d) in good yield.

[0261] To the above compound (A-1-d), 20.0 mmol of 3-iodo-4-vinylbenzoic acid, 30.0 mmol of 1,1'-carbonylbis-1H-imidazole, and 100 g of dichloromethane were added and the mixture was stirred at room temperature for 12 hours. After adding saturated ammonium chloride aqueous solution to terminate the reaction, dichloromethane was added for extraction, and the organic layer was separated. The obtained organic layer was washed with saturated sodium chloride aqueous solution, and then with water. After drying over sodium sulfate, the solvent was removed by distillation, and the compound (A-1) represented by the above formula (A-1) was purified by column chromatography to obtain compound (A-1) in good yield.

[0262] [Examples A2 to A22] (Synthesis of monomers (A-2) to (A-22)) Monomers represented by the following formulas (A-2) to (A-22) were synthesized in the same manner as in Example A1, except that the raw materials and precursors were appropriately changed.

[0263]

[0264]

[0265]

[0266] [Example B1] (Synthesis of monomer (B-1)) Compound (B-1) was synthesized according to the following synthesis scheme.

[0267]

[0268] 20.0 mmol of the above compound (A-1-b), 20.0 mmol of 5-vinylbenzoic acid, 30.0 mmol of sodium bicarbonate, 50 g of dichloromethane, and 50 g of water were added to a reaction vessel and stirred at room temperature for 4 hours. Dichloromethane was added to the reaction mixture and extracted, and the organic layer was separated. The obtained organic layer was washed with saturated sodium chloride aqueous solution, and then with water. After drying over sodium sulfate, the solvent was removed by distillation to obtain compound (B-1) represented by the above formula (B-1) in good yield.

[0269] [Examples B2 to B9] (Synthesis of monomers (B-2) to (B-9)) Monomers represented by the following formulas (B-2) to (B-9) were synthesized in the same manner as in Example B1, except that the raw materials and precursors were appropriately changed.

[0270]

[0271] Among the monomers used in the synthesis of each polymer, monomers other than monomers (A-1) to (A-22) and monomers (B-1) to (B-9) are shown below. Hereinafter, compounds represented by formulas (M-1) to (M-20), formulas (a-1) to (a-5), and formula (b-1) may be referred to as "compound (M-1)" to "compound (M-20)" or "monomer (M-1)" to "monomer (M-20)," respectively.

[0272]

[0273]

[0274] <Synthesis of Polymers> In the following synthesis examples, unless otherwise specified, parts by mass refers to the value when the total mass of the monomers used is set to 100 parts by mass, and mol% refers to the value when the total number of moles of the monomers used is set to 100 mol%.

[0275] [Example P1] (Synthesis of Polymer (P-1)) Monomer (A-1), monomer (M-1), and monomer (M-9) were dissolved in 1-methoxy-2-propanol (200 parts by mass) in a molar ratio of 15 / 40 / 45 (mol%), and AIBN (azobisisobutyronitrile) (5 mol% relative to the total 100 mol% of monomers used) was added as an initiator to prepare a monomer solution. 100 parts by mass of 1-methoxy-2-propanol was placed in an empty reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C, and the monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the completion of the polymerization reaction, the polymerization solution was cooled to below 30°C by water cooling. The cooled polymerization solution was added to hexane (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane, filtered again, and dried at 50°C for 10 hours to obtain a white powdery polymer (P-1) (yield: 85%). The Mw of polymer (P-1) was 7,500, and the Mw / Mn ratio was 1.50. １３ ¹³C-NMR analysis revealed that the content percentages of each structural unit derived from monomer (A-1), monomer (M-1), and monomer (M-9) were 16.0 mol%, 41.5 mol%, and 42.5 mol%, respectively.

[0276] [Examples P2-47 and Comparative Examples CP1-7] (Synthesis of polymers (P-2) to polymer (P-47) and polymer (CP-1) to polymer (CP-7)) Polymers (P-2) to polymer (P-47) and polymer (CP-1) to polymer (CP-7) were synthesized in the same manner as in Example P1, except that monomers of the types and blending ratios shown in Tables 1-1 to 1-3 below were used. The content percentage (mol%) and physical properties (Mw and Mw / Mn) of each structural unit of the obtained polymers are shown in Tables 1-1 to 1-3 below.

[0277]

[0278]

[0279]

[0280] [Example PF1] (Synthesis of high-fluorine-content polymer (PF-1)) Monomers (M-9), (M-17), (M-18), and (B-1) were dissolved in 200 parts by mass of 2-butanone to a molar ratio of 40 / 50 / 5 / 5 (mol%), and MAIB (5 mol%) was added as an initiator to prepare a monomer solution. 100 parts by mass of 2-butanone was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the temperature inside the reaction vessel was set to 80°C, and the monomer solution was added dropwise over 3 hours while stirring. The start of the dropwise addition was defined as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to below 30°C by water cooling. The solvent was replaced with acetonitrile (400 parts by mass), and hexane (100 parts by mass) was added and stirred, and the acetonitrile layer was recovered. This process was repeated three times. By substituting the solvent with propylene glycol monomethyl ether acetate, a solution of the high-fluorine-content polymer (PF-1) was obtained (yield: 78%). The Mw of the high-fluorine-content polymer (PF-1) was 7,200, and the Mw / Mn ratio was 1.67. １３ ¹³C-NMR analysis revealed that the content percentages of each structural unit derived from (M-9), (M-17), (M-18), and (B-1) were 40.4 mol%, 49.8 mol%, 5.4 mol%, and 4.4 mol%, respectively.

[0281] [Synthesis Example F1] (Synthesis of High Fluorine-Content Polymer (F-1)) Monomers (M-9), (M-17), and (M-18) were dissolved in 2-butanone (200 parts by mass) in a molar ratio of 45 / 50 / 5 (mol%), and MAIB (5 mol%) was added as an initiator to prepare a monomer solution. The subsequent procedure was the same as in Example PF1 to synthesize the high fluorine-content polymer (F-1). The Mw of the high fluorine-content polymer (F-1) was 7,500, and the Mw / Mn was 1.70. １３ ¹³C-NMR analysis revealed that the content of each structural unit derived from (M-9), (M-17), and (M-18) was 45.6 mol%, 49.3 mol%, and 5.1 mol%, respectively.

[0282] [C] Radiation-sensitive acid generators C-1 to C-3: Compounds represented by the following formulas (C-1) to (C-3)

[0283]

[0284] [D] Acid diffusion control agents D-1 to D-3: Compounds represented by the following formulas (D-1) to (D-3)

[0285]

[0286] [Solvents] E-1: Propylene glycol monomethyl ether acetate E-2: Propylene glycol monomethyl ether E-3: Methyl 2-hydroxyisobutyrate E-4: Diacetone alcohol E-5: γ-Butyrolactone

[0287] [Preparation of positive-type radiation-sensitive composition for extreme ultraviolet (EUV) exposure] [Example 1] Radiation-sensitive composition (J-1) was prepared by mixing 100 parts by mass of (P-1) as polymer (A), 35.0 parts by mass of (D-1) as acid diffusion control agent (D), 5.0 parts by mass (solids) of (F-1) as high-fluorine-content polymer (F), and 7,000 parts by mass of a mixed solvent of (E-1) / (E-2) as solvent (E), and filtering the mixture through a membrane filter with a pore size of 0.2 μm.

[0288] [Examples 2-48 and Comparative Examples 1-6] Radiation-sensitive compositions (J-2) to (J-48) and (CJ-1) to (CJ-6) were prepared in the same manner as in Example 1, except that the components of the types and amounts shown in Table 2 below were used.

[0289]

[0290] <Formation of a resist pattern using a positive-type radiation-sensitive composition for EUV exposure> An anti-reflective underlayer film (ARC66 from Brewer Sciences) was applied to a 12-inch silicon wafer using a spin coater (CLEAN TRACK ACT12 from Tokyo Electron Limited), and then heated at 205°C for 60 seconds to form an anti-reflective underlayer film with an average thickness of 105 nm. The prepared positive-type radiation-sensitive composition for EUV exposure was applied to this anti-reflective underlayer film using the spin coater, and PB (plate blot) was performed at 130°C for 60 seconds. Subsequently, a resist film with an average thickness of 65 nm was formed by cooling at 23°C for 30 seconds. Next, the resist film was exposed using an EUV lithography system (ASML's "NXE3300") with NA = 0.33, illumination conditions: Conventional s = 0.89, and mask: imecDEFECT32FFR02. After exposure, PEB was performed at 120°C for 60 seconds. Subsequently, the resist film was alkaline developed using a 2.38 mass% TMAH aqueous solution as the alkaline developer, washed with water after development, and then dried to form a positive-type resist pattern (30 nm contact hole pattern).

[0291] <Evaluation> The sensitivity, CDU, and number of development defects of the resist patterns formed using the above-mentioned positive-type radiation-sensitive composition for EUV exposure were evaluated according to the following method. The results are shown in Table 3 below. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000") was used to measure the length of the resist patterns.

[0292] [Sensitivity] In forming a resist pattern using the above-mentioned positive-type radiation-sensitive composition for EUV exposure, the exposure amount used to form a 30 nm contact hole pattern is defined as the optimal exposure amount, and this optimal exposure amount is defined as the sensitivity (mJ / cm²). ２ The sensitivity was set to 40 mJ / cm². ２ In the following cases, it is considered "good" and 40 mJ / cm². ２ If it exceeded this value, it was rated as "poor."

[0293] [CDU] The mask size was adjusted to form a 30 nm contact hole pattern by irradiating with the optimal exposure amount determined in the sensitivity evaluation above, and a resist pattern was formed. The formed resist pattern was observed from the top of the pattern using the scanning electron microscope described above. The hole diameter was measured at 16 points in the range of 500 nm and the average value was calculated. This average value was then measured at a total of 500 points at arbitrary points, and the 1 sigma value was calculated from the distribution of the measured values, and this was defined as the CDU performance (nm). The smaller the CDU performance value, the smaller the variation in hole diameter over long periods, and the better the performance. CDU performance was evaluated as "good" if it was 2.5 nm or less, and as "poor" if it was greater than 2.5 nm.

[0294] [Development Defect Count] A 30 nm contact hole pattern was formed by exposing a resist film with the optimal exposure dose, and this was used as a wafer for defect inspection. The number of defects on this wafer for defect inspection was measured using a defect inspection device (KLA-Tencor's "KLA2810"). Defects with a diameter of 50 μm or less were judged to be originating from the resist film, and their number was calculated. After development, the defect count was evaluated as "good" if the number of defects judged to be originating from the resist film was 50 or less, and as "poor" if it exceeded 50.

[0295]

[0296] As is clear from the results in Table 3, the radiation-sensitive composition of the example showed good sensitivity, CDU, and development defect performance when used in EUV exposure, whereas the comparative example exhibited inferior characteristics compared to the example.

[0297] [Preparation of positive-type radiation-sensitive composition for ArF immersion exposure] [Example 49] 100 parts by mass of (P-19) as polymer (P), 8.0 parts by mass of (D-1) as acid diffusion control agent (D), 3.0 parts by mass (solids) of (F-1) as high-fluorine-content polymer (F), and 2,730 parts by mass of a mixed solvent of (E-1) / (E-2) / (E-3) as solvent (E) were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive composition (J-49).

[0298] [Examples 50-56 and Comparative Example 7] Radiation-sensitive compositions (J-50) to (J-56) and (CJ-7) were prepared in the same manner as in Example 49, except that the components of the types and amounts shown in Table 5 below were used.

[0299]

[0300] <Formation of a resist pattern using a positive-type radiation-sensitive composition for ArF immersion lithography> An anti-reflective underlayer film formation composition ("ARC66" from Brewer Science) was applied to a 12-inch silicon wafer using a spin coater ("CLEAN TRACK ACT12" from Tokyo Electron Limited), and then heated at 205°C for 60 seconds to form an anti-reflective underlayer film with an average thickness of 100 nm. The positive-type radiation-sensitive composition for ArF lithography prepared above was applied to this anti-reflective underlayer film using the same spin coater, and pre-bake (PB) was performed at 100°C for 60 seconds. Subsequently, a resist film with an average thickness of 120 nm was formed by cooling at 23°C for 30 seconds. Next, the resist film was exposed to a 50 nm line-and-space pattern using an ArF excimer laser immersion lithography system (ASML's "TWINSCAN XT-1900i") under optical conditions of NA = 1.35 and Dipole (σ = 0.9 / 0.7). After exposure, post-exposure baking (PEB) was performed at 100°C for 60 seconds. Subsequently, the resist film was alkaline developed using a 2.38 mass% TMAH aqueous solution as the alkaline developer, washed with water after development, and then dried to form a positive-type resist pattern (50 nm line-and-space pattern).

[0301] <Evaluation> The sensitivity, LWR, MEEF, and pattern rectangularity of the resist patterns formed using the above ArF immersion exposure positive-type radiation-sensitive composition were evaluated according to the following method. The results are shown in Table 5 below. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000") was used to measure the length of the resist patterns.

[0302] [Sensitivity] In forming a resist pattern using the above ArF immersion lithography positive-type radiation-sensitive composition, the exposure amount used to form a 50 nm line-and-space pattern is defined as the optimal exposure amount, and this optimal exposure amount is defined as the sensitivity (mJ / cm²). ２ The sensitivity was set to 30 mJ / cm². ２ The following conditions are considered "good": 30 mJ / cm² ２ If it exceeded this value, it was rated as "poor."

[0303] [LWR] A 50 nm line-and-space resist pattern was formed by irradiating with the optimal exposure amount determined in the sensitivity evaluation above. The formed resist pattern was observed from the top of the pattern using the scanning electron microscope described above. The variation in line width was measured at a total of 500 points, and the 3-sigma value was determined from the distribution of these measurements. This 3-sigma value was defined as LWR (nm). A smaller LWR value indicates less line roughness and better quality. An LWR of 3.0 nm or less was evaluated as "good," and an LWR greater than 3.0 nm was evaluated as "poor."

[0304] [MEEF] For resist patterns resolved by irradiating with the optimal exposure amount described above, the slope of the straight line was calculated when the line width of the resist pattern formed using mask patterns with line widths of 52 nm, 54 nm, 56 nm, 58 nm, and 60 nm was plotted on the vertical axis and the line width of the mask pattern on the horizontal axis, and this was defined as MEEF. A MEEF value closer to 1 indicates better mask reproducibility. MEEF values ​​of 2 or less were evaluated as "good," and values ​​greater than 2 were evaluated as "poor."

[0305] [Pattern Rectangularity] The 50 nm line and space pattern formed by irradiating with the optimal exposure amount determined in the sensitivity evaluation above was observed using the scanning electron microscope described above, and the cross-sectional shape of the line pattern was evaluated. The rectangularity of the resist pattern was evaluated as follows: if the ratio of the length of the lower side to the length of the upper side in the cross-sectional shape of the line pattern was 1 or more and 1.05 or less, it was evaluated as "A" (very good); if it was greater than 1.05 and 1.10 or less, it was evaluated as "B" (good); and if it was greater than 1.10, it was evaluated as "C" (poor).

[0306]

[0307] As is clear from the results in Table 5, the radiation-sensitive composition of the example showed good sensitivity, LWR, MEEF, and pattern shape when used in ArF exposure, whereas the comparative example showed inferior characteristics compared to the example.

[0308] The radiation-sensitive composition, pattern formation method, polymer, and compound described above enable the formation of resist patterns with good sensitivity to exposure light and excellent CDU, LWR, MEEF, development defect performance, and pattern shape. Therefore, these can be suitably used in semiconductor device processing processes and the like, where further miniaturization is expected in the future.

Claims

1. A radiation-sensitive composition containing a polymer comprising a structural unit (I) derived from a compound represented by the following formula (1) and a solvent. (In formula (1), １ R is a monovalent organic group having 1 to 40 carbon atoms. However, when - A is -SO ３ - R is a monovalent organic group having 3 to 40 carbon atoms containing a cyclic structure. １ A is -SO - ３ - - - ２ -COO - or -N or -N-SO -R Ｘ R is a monovalent organic group having 1 to 20 carbon atoms. Ｘ R is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. ２ R is a hydroxy group or a monovalent organic group having 1 to 20 carbon atoms. ３ R ４ and R ５ are each independently a monovalent organic group having 1 to 20 carbon atoms, or ４ R and ４ R together represent a ring structure having 4 to 12 carbon atoms formed together with the sulfur atom to which they are bonded. ５ ６ R is a halogen atom, a hydroxy group, a nitro group, an amino group, a carboxy group, a cyano group or a monovalent organic group having 1 to 20 carbon atoms. When there are a plurality of ６ R, the plurality of ６ R are the same or different from each other. However, any one of １ R to ６ R has one polymerizable group. ３ m is 0 or 1. When m is 1, both ２ -CO- and R ２ [[ID=5.O- are bonded to the 6-membered ring structure to which the sulfur atom in the above formula (1) is bonded. n is an integer of 0 to 4. ) 2. In the above formula (1), R １ The radiation-sensitive composition according to claim 1, wherein one polymerizable group is present.

3. In the above formula (1), R ３ The radiation-sensitive composition according to claim 1, wherein is a monovalent organic group having 1 to 20 carbon atoms and having an ether bond on the bonding side.

4. The radiation-sensitive composition according to claim 1, wherein m is 0 in formula (1) above.

5. In the above formula (1), R ２ -O- vs R ３ The radiation-sensitive composition according to claim 1, wherein -CO- is in an ortho or para position.

6. In the above formula (1), R ２ The radiation-sensitive composition according to claim 1, wherein is a hydrogen atom, an alkyl group, an alkoxyalkyl group, an alkoxycarbonylalkyl group, or a cycloalkoxycarbonylalkyl group.

7. In the above formula (1), R １ The radiation-sensitive composition according to claim 1, comprising at least one structure selected from the group consisting of a carbonyl group and an ether bond, and a cyclic structure.

8. In the above formula (1), A - is, -SO ３ - And, -SO ３ - R relative to the sulfur atom inside １ The radiation-sensitive composition according to claim 1, wherein a cyano group, a fluorine atom, or a fluorinated hydrocarbon group is bonded to the α-carbon or β-carbon in the composition.

9. The radiation-sensitive composition according to claim 8, wherein the content of the structural unit (I) in the total structural units constituting the polymer is 1 mol% or more and 30 mol% or less.

10. In the above formula (1), A - -COO - A - is, -SO ３ - And, -SO ３ - R relative to the sulfur atom inside １ The radiation-sensitive composition according to claim 1, wherein no cyano group, fluorine atom, or fluorinated hydrocarbon group is bonded to the α-carbon or β-carbon in the composition.

11. The radiation-sensitive composition according to claim 10, wherein the content of the structural unit (I) in relation to the total structural units constituting the polymer is 1 mol% or more and 20 mol% or less.

12. The radiation-sensitive composition according to claim 1, wherein the polymer further comprises a structural unit (II) having an acid-dissociable group.

13. The above structural unit (II) is represented by the following formula (3), the radiation-sensitive composition according to claim 12. (In formula (3), R １７ R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. １８ R is a monovalent substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms. １９ and R ２０ Each of these independently represents either a monovalent substituted or unsubstituted linear hydrocarbon group having 1 to 10 carbon atoms, a monovalent substituted or unsubstituted alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a divalent alicyclic group having 3 to 20 carbon atoms formed by combining these groups with the carbon atoms to which they are bonded. ３１ teeth, ＊ -COO- or ＊ -L ３１ａ Represents COO-. ３１ａ * is a substituted or unsubstituted alkanediyl group or arenediyl group. １７ This is the bonding site with the carbon atom to which it is bonded.

14. A pattern forming method comprising the steps of: applying a radiation-sensitive composition according to any one of claims 1 to 13 directly or indirectly to a substrate to form a resist film; exposing the resist film; and developing the exposed resist film with a developer.

15. The pattern formation method according to claim 14, wherein the exposure is performed using an ArF excimer laser or extreme ultraviolet light.

16. A polymer containing structural unit (I) derived from a compound represented by the following formula (1). (In formula (1), R １ A is a monovalent organic group having 1 to 40 carbon atoms. However, A - ga-SO ３ - If R １ A is a monovalent organic group with 3 to 40 carbon atoms that includes a cyclic structure. - is, -SO ３ - ,-COO - or -N - -SO ２ -R Ｘ That is. R Ｘ R is a monovalent organic group having 1 to 20 carbon atoms. ２ R is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. ３ R is a hydroxyl group or a monovalent organic group having 1 to 20 carbon atoms. ４ and R ５ Each of these is independently a monovalent organic group having 1 to 20 carbon atoms, or R ４ and R ５ These can be combined to form a ring structure with 4 to 12 carbon atoms, along with the sulfur atoms to which they are bonded. ６ R is a halogen atom, hydroxyl group, nitro group, amino group, carboxyl group, cyano group, or a monovalent organic group having 1 to 20 carbon atoms. ６ If multiple R ６ They are either identical or different from each other. However, R １ ~R ６ One of them has one polymerizable group. m is 0 or 1. If m is 1, R ３ -CO- and R ２ Both -O- atoms bond to the six-membered ring structure to which the sulfur atom in formula (1) above is bonded. (n is an integer from 0 to 4.) 17. A compound represented by the following formula (1). (In formula (1), １ R is a monovalent organic group having 1 to 40 carbon atoms. However, when - A is -SO ３ - R is a monovalent organic group having 3 to 40 carbon atoms including a cyclic structure. １ A is -SO - is -SO ３ - -COO - or -N - -SO ２ -R Ｘ is. Ｘ R is a monovalent organic group having 1 to 20 carbon atoms. ２ R is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. ３ R is a hydroxy group or a monovalent organic group having 1 to 20 carbon atoms. ４ R ５ and R ４ and R ５ are each independently a monovalent organic group having 1 to 20 carbon atoms, or ６ R and R ６ together represent a ring structure having 4 to 12 carbon atoms formed together with the sulfur atom to which they are bonded. ６ R １ to R ６ any one of which has one polymerizable group. ３ m is 0 or 1. When m is 1, ２ both R-CO- and R-O- are bonded to the 6-membered ring structure to which the sulfur atom in the above formula (1) is bonded. n is an integer of 0 to 4. )

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