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

Abstract

Provided is a radiation-sensitive composition or the like, which has satisfactory storage stability and can exhibit sensitivity, LWR, and Min CD at levels equal to or higher than conventional levels, at the time of pattern formation. The radiation-sensitive composition comprises a polymer containing a structural unit (I) having an acid-dissociable group, and a solvent, wherein the polymer has a partial structure (w) represented by formula (w1) or (w2), or the radiation-sensitive composition contains an onium salt compound having a partial structure (w) represented by formula (w1) or (w2).　Formula 1 (At least one selected from the group consisting of R1, R2, and R3 is an iodine atom or a bromine atom. X is an iodine atom or a bromine atom.)

Description

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

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

[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 solvent-based 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, or combine this radiation with liquid immersion lithography to advance pattern miniaturization. As a next-generation technology, efforts are being made to utilize even shorter-wavelength radiation such as electron beams, X-rays, and EUV (extreme ultraviolet).

[0004] As pattern miniaturization progresses, there is a need to improve resist performance such as sensitivity, and development is also progressing on quenchers, which are a component of resist materials (Japanese Patent Publication No. 7351257).

[0005] Patent No. 7351257

[0006] In deploying the above-mentioned next-generation technologies, the resist composition is required to have storage stability, sensitivity, LWR (Line Width Roughness) which indicates the variation in line width and resist pattern line width, and Min CD which is an indicator of resolution in low exposure areas, as well as other resist performance characteristics equivalent to or better than those of conventional resists.

[0007] The present invention aims to provide a radiation-sensitive composition, a pattern-forming method, an onium salt compound, and a polymer that have good storage stability and can exhibit sensitivity, LWR, and Min CD at levels equivalent to or better than conventional methods 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] In one embodiment, the present invention relates to a radiation-sensitive composition containing a polymer having a structural unit (I) with an acid-dissociable group and a solvent, wherein the polymer has a partial structure (w) represented by the following formula (w1) or (w2), or the radiation-sensitive composition contains an onium salt compound, and the onium salt compound has a partial structure (w) represented by the following formula (w1) or (w2) and generates an acid that dissociates the acid-dissociable group of the polymer upon exposure, and the radiation-sensitive composition contains at least one onium salt compound selected from the group consisting of an onium salt compound (1) and an onium salt compound (2) that has a partial structure (w) represented by the following formula (w1) or (w2) and does not dissociate the acid-dissociable group of the polymer upon exposure. (In formula (w1), R １ , R ２ and R ３ are each independently a hydrogen atom, a halogen atom, a nitro group or a monovalent organic group having 1 to 10 carbon atoms, or one selected from the group consisting of R １ , R ２ and R ３ is an iodine atom or a bromine atom, and the remaining two are combined with each other to form a ring structure having 5 to 20 carbon atoms. However, at least one selected from the group consisting of R １ , R ２ and R ３ is an iodine atom or a bromine atom. In formula (w2), X is an iodine atom or a bromine atom. * is a bond to another structure in the corresponding component.)

[0010] In this radiation-sensitive composition, the above substructure (w) is introduced into at least one of the onium salt compounds, whether polymers or radiation-sensitive acid generators or acid diffusion controllers (quenchers), thereby achieving good storage stability and exhibiting sensitivity, LWR, and Min CD at or above the level of conventional compositions. Although the reason for this is not entirely clear, it is presumed that the following is the case: The iodine atoms or bromine atoms (hereinafter also referred to as "iodine atoms, etc.") contained in the above substructure (w) increase the radiation absorption efficiency and improve the secondary electron generation efficiency, thereby improving sensitivity and LWR. Conventionally, when introducing iodine atoms, etc., they were often introduced onto aromatic rings. However, by introducing them into the above substructure (w), which is simple and has a relatively hydrophilic structure, the relative abundance of iodine atoms, etc. in the onium salt compound increases, and sensitivity, LWR, and Min CD can be improved more efficiently. Furthermore, while introducing iodine atoms, etc., onto a saturated hydrocarbon structure may reduce chemical stability, sufficient chemical stability can be obtained by introducing them into the above substructure (w). It is presumed that the above-mentioned resist performance and other properties are achieved 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 above-mentioned 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] This pattern formation method uses the above-mentioned radiation-sensitive composition, which exhibits excellent storage stability as well as superior sensitivity, LWR, and Min CD during pattern formation, thus enabling the efficient formation of high-quality resist patterns.

[0013] In another embodiment, the present invention relates to an onium salt compound having an organic acid anion and an onium cation, generating acid upon exposure, and having a substructure (w) represented by the following formula (w1) or (w2). (In formula (w1), R １ , R ２ and R ３Each of these is independently a hydrogen atom, a halogen atom, a cyano group, a nitro group, or a monovalent organic group having 1 to 10 carbon atoms, or R １ , R ２ and R ３ One of the group consisting of is selected to be an iodine atom or a bromine atom, and the remaining two are combined with each other to form a ring structure with 5 to 20 carbon atoms. However, R １ , R ２ and R ３ At least one atom selected from the group consisting of is either an iodine atom or a bromine atom. In formula (w2), X is either an iodine atom or a bromine atom. * represents a bond with another structure in the onium salt compound.

[0014] The onium salt compound has the above-described substructure (w) and possesses characteristics such as high secondary electron generation efficiency, a hydrophilic structure, and chemical stability, making it suitable as a radiation-sensitive acid generator or acid diffusion control agent in radiation-sensitive compositions.

[0015] In yet another embodiment, the present invention relates to a polymer comprising a structural unit (I) having an acid-dissociable group and having a substructure (w) represented by the following formula (w1) or (w2). (In formula (w1), R １ , R ２ and R ３ Each of these is independently a hydrogen atom, a halogen atom, a cyano group, a nitro group, or a monovalent organic group having 1 to 10 carbon atoms, or R １ , R ２ and R ３ One of the group consisting of is selected to be an iodine atom or a bromine atom, and the remaining two are combined with each other to form a ring structure with 5 to 20 carbon atoms. However, R １ , R ２ and R ３ At least one atom selected from the group consisting of is either an iodine atom or a bromine atom. In formula (w2), X is either an iodine atom or a bromine atom. * represents a bond with other structures in the polymer.

[0016] The polymer has the above-mentioned substructure (w) and possesses the characteristics of high secondary electron generation efficiency, hydrophilic structure, and chemical stability, making it suitable as a base polymer in radiation-sensitive compositions.

[0017] In this specification, "organic group" means a group having at least one carbon atom (excluding groups that constitute a functional group or characteristic group on their own, such as -CN, -COOH, -CO-, -COO-, -O-CO-O-, etc.).

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

[0019] 《Radiation-Sensitive Composition》 The radiation-sensitive composition according to this embodiment (hereinafter also simply referred to as "composition") contains at least a polymer (hereinafter also referred to as "base polymer") and a solvent. In the composition, a predetermined substructure (w) is introduced into the polymer, or an onium salt compound is included in the composition and the substructure (w) is introduced into the onium salt compound. If the composition contains an onium salt compound, the onium salt compound includes at least one onium salt compound selected from the group consisting of an onium salt compound (1) as a radiation-sensitive acid generator and an onium salt compound (2) as an acid diffusion control agent. The above composition may contain other optional components as long as they do not impair the effects of the present invention.

[0020] <Polymers> A polymer (i.e., a base polymer) is an aggregate of polymerization chains containing structural unit (I) having an acid-dissociable group. In addition to structural unit (I), the base polymer may also contain structural units containing acid-generating structures (hereinafter also referred to as "structural unit (II)" and "structural unit (III)" depending on the acid generated), structural units having phenolic hydroxyl groups (hereinafter also referred to as "structural unit (IV)"), structural units containing lactone structures, etc. (hereinafter also referred to as "structural unit (V)"), structural units containing polar groups (hereinafter also referred to as "structural unit (VI)"), etc.

[0021] (Structural Unit (I)) Structural Unit (I) is a structural unit having an acid-dissociable group. Upon exposure, the acid generated from the acid-generating structure in the case where the base polymer contains structural Unit (II) or from the above-mentioned radiation-sensitive acid generator dissociates the acid-dissociable group in structural Unit (I), generating carboxyl groups, etc. This creates a difference in solubility in the developer between the exposed and unexposed areas of the resist film, enabling pattern formation.

[0022] The structural unit (I) is not particularly limited as long as it has an acid-dissociable group, and examples include a structural unit having a tertiary alkyl ester moiety, a structural unit having an ester moiety derived from a secondary alcohol having an aromatic ring group and an aliphatic hydrocarbon group, a structural unit having a structure in which the hydrogen atom of a phenolic hydroxyl group is replaced by a tertiary alkyl group, and a structural unit having an acetal bond. From the viewpoint of improving the pattern-forming properties of the radiation-sensitive composition, the structural unit represented by the following formula (1) (hereinafter also referred to as "structural unit (I-1)") is preferred.

[0023] (In formula (1), R ａ L is a hydrogen atom, a fluorine atom, a methyl group, or a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms. α R is a divalent linking group. １Ａ and R １Ｂ Each of these independently represents a hydrogen atom, a monovalent linear hydrocarbon group having 1 to 10 carbon atoms, or a monovalent 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. However, R １Ａ and R １Ｂ It is not possible for both to be hydrogen atoms. １ This is an aromatic ring with 5 to 20 members and a (p+q+1) valency. １０１ R is a nitro group, cyano group, hydroxyl group, alkoxy group, or amino group. １０１ If multiple R １０１m1 and m2 are either identical or different. m1 and m2 are independently either 0 or 1. However, when m1 is 1, m2 is also 1. p is an integer between 1 and 3. q is an integer between 0 and 3. However, p + q is less than or equal to 5.

[0024] R ａ Examples of C1-C6 alkyl groups represented by include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, t-butyl group, n-pentyl group, isopentyl group, neopentyl group, and the like.

[0025] R ａ When an alkyl group having 1 to 6 carbon atoms represented by has substituents, examples of substituents include halogen atoms such as fluorine, chlorine, bromine, and iodine atoms; hydroxyl groups; carboxyl groups; cyano groups; nitro groups; amino 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.

[0026] R ａ Examples of alkoxy groups as substituents include linear or branched alkoxy groups having 1 to 8 carbon atoms, such as methoxy, ethoxy, and propoxy groups. Examples of alkoxycarbonyl groups include alkoxycarbonyl groups having 1 to 6 carbon atoms, such as methoxycarbonyl and ethoxycarbonyl groups. Examples of alkoxycarbonyloxy groups include linear or alicyclic alkoxycarbonyloxy groups having 2 to 16 carbon atoms, such as methoxycarbonyloxy, butoxycarbonyloxy, and adamantylmethyloxycarbonyloxy groups. Examples of acyl groups include aliphatic or aromatic acyl groups having 2 to 12 carbon atoms, such as acetyl, propionyl, benzoyl, and acryloyl groups. Examples of acyloxy groups include aliphatic or aromatic acyloxy groups having 2 to 12 carbon atoms, such as acetyloxy, propionyloxy, benzoyloxy, and acryloyloxy groups.

[0027] The above R ａFrom the viewpoint of copolymerizability of the monomer that gives structural unit (I-1), hydrogen atoms and methyl groups are preferred.

[0028] L α Examples of divalent linking groups represented by include divalent hydrocarbon groups such as alkanediyl groups, cycloalkanediyl groups, alkenediyl groups, or arenediyl groups; divalent heteroatom-containing groups; groups in which the divalent heteroatom-containing group is incorporated between the carbon-carbon bonds of the divalent hydrocarbon group; or groups combining these. R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. Examples of divalent heteroatom-containing groups include -CO-, -CS-, -O-, -S-, and -SO ２ -, -NR'-, or a combination of two or more of these groups. Some or all of the hydrogen atoms in these groups are R ａ It may be substituted with substituents that it may have.

[0029] The alkanediyl group described above is preferably an alkanediyl group having 1 to 8 carbon atoms, such as a methanediyl group, an ethanediyl group, a 1,3-propanediyl group, or a 2,2-propanediyl group.

[0030] Examples of the above-mentioned cycloalkanediyl groups include monocyclic cycloalkanediyl groups such as cyclopentanediyl and cyclohexanediyl groups; and polycyclic cycloalkanediyl groups such as norbornanediyl and adamantanediyl groups. A cycloalkanediyl group having 5 to 12 carbon atoms is preferred.

[0031] Examples of the alkenediyl group mentioned above include ethendiyl group, propenediyl group, and butenediyl group. A preferred alkenediyl group is one having 2 to 6 carbon atoms.

[0032] Examples of the above-mentioned arenediyl group include a phenylene group, a torylene group, a naphthylene group, and the like. A preferred arenediyl group is one having 6 to 15 carbon atoms.

[0033] L αThe divalent linking group represented by is preferably an alkanediyl group or an arenediyl group, more preferably an alkanediyl group having 1 to 4 carbon atoms or an arenediyl group having 6 to 10 carbon atoms, and even more preferably a methanediyl group or a benzenediyl group.

[0034] R １Ａ and R １Ｂ Examples of monovalent linear hydrocarbon groups having 1 to 10 carbon atoms include monovalent linear or branched saturated hydrocarbon groups having 1 to 10 carbon atoms, or monovalent linear or branched unsaturated hydrocarbon groups having 1 to 10 carbon atoms. Examples of the above monovalent linear or branched saturated hydrocarbon groups having 1 to 10 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, 2-methylpropyl, 1-methylpropyl, t-butyl, n-pentyl, isopentyl, and neopentyl groups. Examples of monovalent linear or branched unsaturated hydrocarbon groups having 2 to 10 carbon atoms include alkenyl groups such as ethenyl, propenyl, and butenyl groups; and alkynyl groups such as ethynyl, propynyl, and butynyl groups.

[0035] R １Ａ and R １Ｂ Examples of monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, represented by , include monocyclic or polycyclic saturated hydrocarbon groups, or monocyclic or polycyclic unsaturated hydrocarbon groups. Preferred monocyclic saturated hydrocarbon groups are cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. Preferred polycyclic cycloalkyl groups are bridged alicyclic hydrocarbon groups such as norbornyl, adamantyl, tricyclodecyl, and tetracyclododecyl groups. Examples of monocyclic unsaturated hydrocarbon groups are monocyclic cycloalkenyl groups such as cyclopropenyl, cyclobutenyl, cyclopentenyl, and cyclohexenyl groups. Examples of polycyclic unsaturated hydrocarbon groups are polycyclic cycloalkenyl groups such as norborneyl, tricyclodecenyl, and tetracyclododecenyl groups. A bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two non-adjacent carbon atoms constituting the alicyclic ring are linked by a linking group containing one or more carbon atoms.

[0036] R １Ａ and R １Ｂ As a divalent alicyclic group having 3 to 20 carbon atoms that is formed when these are combined with each other and bonded together with the carbon atoms, a group obtained by removing one hydrogen atom from the above-mentioned monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms can be suitably adopted.

[0037] R １Ａ and R １Ｂ Examples include monovalent chain hydrocarbon groups having 1 to 10 carbon atoms, or R １Ａ and R １Ｂ Divalent alicyclic groups having 3 to 20 carbon atoms are preferred, formed by combining these groups with the carbon atoms to which they are bonded; monovalent linear hydrocarbon groups having 1 to 10 carbon atoms or divalent alicyclic groups having 5 to 10 carbon atoms are more preferred; and methyl groups, ethyl groups, cyclopentanediyl groups, and cyclohexanediyl groups are even more preferred.

[0038] Ar １ The aromatic ring in is not particularly limited as long as it is an aromatic ring structure. Examples of aromatic rings include aromatic hydrocarbon rings such as benzene rings, naphthalene rings, anthracene rings, phenalene rings, phenanthrene rings, pyrene rings, fluorene rings, perylene rings, and coronene rings; 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, triazine rings, carbazole rings, and dibenzofuran rings; or combinations thereof. Among these, Ar １ The aromatic ring in is preferably a benzene ring, a thiophene ring, or a furan ring, with a benzene ring being more preferred. １ As an aromatic ring with 5 to 20 members and a (p+q+1) value, represented by the above Ar １ A group obtained by removing (p + q + 1) hydrogen atoms from the aromatic ring can be suitably adopted.

[0039] R １０１ The alkoxy group represented by is R in formula (1) above. ａ The alkoxy group shown is an example of a substituent.

[0040] p is preferably 1 or 2. q is preferably 0 or 1.

[0041] When introducing a substructure (w) into a base polymer, the substructure (w) may be introduced into a structural unit (I). The substructure (w) is a structure represented by the following formula (w1) or (w2). (In formula (w1), R １ , R ２ and R ３ Each of these is independently a hydrogen atom, a halogen atom, a nitro group, or a monovalent organic group having 1 to 10 carbon atoms, or R １ , R ２ and R ３ One of the group consisting of is selected to be an iodine atom or a bromine atom, and the remaining two are combined with each other to form a ring structure with 5 to 20 carbon atoms. However, R １ , R ２ and R ３ At least one atom selected from the group consisting of is either an iodine atom or a bromine atom. In formula (w2), X is either an iodine atom or a bromine atom. * represents a bond with another structure in the corresponding component.

[0042] In formula (w1), R １ ~R ３ Examples of monovalent organic groups having 1 to 10 carbon atoms represented by include monovalent hydrocarbon groups having 1 to 10 carbon atoms, groups (α) having a divalent heteroatom-containing group between carbon atoms of the hydrocarbon group or at the terminal end of the hydrocarbon group, groups in which some or all of the hydrogen atoms of the hydrocarbon group or group (α) are replaced with monovalent heteroatom-containing groups, or combinations thereof.

[0043] Examples of monovalent hydrocarbon groups having 1 to 10 carbon atoms in the above-mentioned organic group include monovalent linear hydrocarbon groups having 1 to 10 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 10 carbon atoms, monovalent aromatic hydrocarbon groups having 6 to 10 carbon atoms, or combinations thereof.

[0044] The above monovalent chain hydrocarbon group having 1 to 10 carbon atoms is R of formula (1) above. １Ａ The monovalent chain hydrocarbon groups having 1 to 10 carbon atoms shown in the above can be suitably used.

[0045] As the above monovalent alicyclic hydrocarbon group having 3 to 10 carbon atoms, R of formula (1) above １Ａ Among the monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms shown above, those corresponding to groups having 3 to 10 carbon atoms are examples.

[0046] Examples of monovalent aromatic hydrocarbon groups having 6 to 10 carbon atoms include aryl groups such as phenyl, tolyl, xyl, and naphthyl groups, and aralkyl groups such as benzyl and phenethyl groups.

[0047] As a divalent heteroatom-containing group, L in formula (1) above is an example. α The divalent heteroatom-containing group shown can be suitably adopted.

[0048] Examples of monovalent heteroatom-containing groups include hydroxyl groups, carboxyl groups, sulfanyl groups, cyano groups, nitro groups, and halogen atoms.

[0049] In formula (w1), R １ ~R ３ The monovalent organic group having 1 to 10 carbon atoms represented by is preferably a monovalent hydrocarbon group having 1 to 10 carbon atoms or a group in which some or all of the hydrogen atoms of the hydrocarbon group are substituted with a monovalent heteroatom-containing group, more preferably a monovalent chain hydrocarbon group having 1 to 5 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms or a group in which some or all of the hydrogen atoms of the aromatic hydrocarbon group are substituted with halogen atoms, and even more preferably a methyl group, a phenyl group or an iodophenyl group.

[0050] R １ , R ２ and R ３ If one selected from the group consisting of is an iodine atom or a bromine atom, the remaining two can be combined to form a ring structure having 5 to 20 carbon atoms, which may be a monocyclic or polycyclic unsaturated hydrocarbon structure that includes a carbon-carbon double bond as in formula (w1), or a group having the above-mentioned divalent heteroatom-containing group between the carbon atoms of this unsaturated hydrocarbon structure.

[0051] The monocyclic or polycyclic unsaturated hydrocarbon structure mentioned above is R in formula (1) above. １ＡStructures corresponding to the monocyclic or polycyclic unsaturated hydrocarbon groups shown above can be mentioned.

[0052] As the ring structure having 5 to 20 carbon atoms, a structure corresponding to the monocyclic unsaturated hydrocarbon group is preferable, a structure corresponding to the monocyclic cycloalkenyl group is more preferable, and a structure corresponding to the cyclohexenyl group is even more preferable.

[0053] In the above formula (w1), at least one selected from the group consisting of R １ , R ２ and R ３ is preferably an iodine atom. It is more preferable that two selected from the group consisting of R １ , R ２ and R ３ are iodine atoms, and it is even more preferable that R １ , R ２ and R ３ are all iodine atoms. Other than the iodine atom in R １ , R ２ and R ３ are preferably a hydrogen atom or a methyl group, and more preferably a hydrogen atom.

[0054] In the above formula (w2), X is preferably an iodine atom.

[0055] Although the specific examples of the partial structure (w) are not particularly limited, for example, the structures represented by the following formulas (w1-1) to (w1-30) and formulas (w2-1) to (w2-2) can be mentioned.

[0056]

[0057]

[0058] When introducing the above partial structure (w) into the structural unit (I-1) represented by the above formula (1), in the above formula (1), at least one selected from the group consisting of L α , R １Ａ , R １Ｂ and Ar １ is preferably bonded with the partial structure (w), and R １Ａ , R １Ｂ and Ar １It is more preferable that the substructure (w) is bonded to at least one selected from the group consisting of Ar １ It is even more preferable that a substructure (w) is bonded to it. α , R １Ａ , R １Ｂ and Ar １ "At least one substructure (w) is bonded to L" means that L α , R １Ａ , R １Ｂ and Ar １ This includes not only the case where a substructure (w) is directly bonded to at least one selected from the group consisting of L, but also L α , R １Ａ , R １Ｂ and Ar １ This also includes the case where the substructure (w) is bonded via a linking group to at least one selected from the group consisting of the above.

[0059] Furthermore, the polymer may contain structural units (I) represented by the following formulas (1f) to (2f).

[0060]

[0061] 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.

[0062] The above R βｆ Preferably, it is a hydrogen atom, a methyl group, or an ethyl group. １ 1 or 2 is preferred.

[0063] While there are no particular limitations on specific examples of structural unit (I) (including structural unit (I-1)), examples include structures represented by the following formulas (1-1) to (1-68).

[0064]

[0065]

[0066]

[0067]

[0068]

[0069]

[0070] In the formula, R ａ This is equivalent to equation (1) above.

[0071] The lower limit of the content of structural unit (I) (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 75 mol%, and even more preferably 70 mol%. By setting the content of structural unit (I) within the above range, the pattern-forming properties of the radiation-sensitive composition can be further improved. If the acid-dissociable group has an iodine group, the sensitivity can be further improved.

[0072] (Structural Unit (II)) The base polymer may include structural unit (II) which has a first organic acid anion and a first onium cation, and which includes a first acid generation structure that generates an acid that dissociates the acid-dissociable group upon exposure. Preferably, at least one selected from the group consisting of the first organic acid anion and the first onium cation has the above substructure (w), and more preferably, the first organic acid anion has the above substructure (w).

[0073] The onium salt structure formed by the first organic acid anion and the first onium cation (i.e., the first acid generation structure) functions as a radiation-sensitive acid generation structure. Because the base polymer contains the above radiation-sensitive acid generation structure, the polarity of the base polymer in the exposed area increases, making it soluble in the developer in the case of alkaline aqueous solution development, while it becomes sparingly soluble in the developer in the case of organic solvent development.

[0074] The form in which the first organic acid anion and the first onium cation are contained in the structural unit (II) of the base polymer is not particularly limited. The base polymer may have the first organic acid anion as a side chain portion, or it may have the first onium cation as a side chain portion. Having it as a side chain portion means that the corresponding first organic acid anion or first onium cation is bonded (covalently bonded) to the main chain as a side chain structure of the base polymer. When the first organic acid anion is bonded to the main chain as a side chain structure of the base polymer, the first onium cation is ionically bonded to the first organic acid anion as its counterion. On the other hand, when the first onium cation is bonded to the main chain as a side chain structure of the base polymer, the first organic acid anion is ionically bonded to the first onium cation as its counterion. From the viewpoint of controlling the acid diffusion length, it is preferable that the base polymer has the first organic acid anion as a side chain portion.

[0075] The above-mentioned first organic acid anion preferably has at least one selected from the group consisting of sulfonic acid anions and sulfonimide anions as the acid anion portion, and more preferably has a sulfonic acid anion. As the acid generated by exposure, sulfonic acid and sulfonimide can be given, corresponding to the above-mentioned acid anion portion.

[0076] The above-mentioned first organic acid anion preferably includes, as a structure other than the acid anion portion, -O-, -CO-, a cyclic structure, or a combination thereof. This combination also includes structures (heterocyclic structures) in which -O- or -CO- are incorporated as ring-forming parts within the cyclic structure.

[0077] The cyclic structure may be monocyclic, polycyclic, or a combination thereof. Furthermore, the cyclic structure may be alicyclic, aromatic, heterocyclic, or a combination thereof. In the case of a combination, the cyclic structures may be linked by a chain structure, and two or more cyclic structures may form a fused ring structure, a bridged ring structure, or a spiro-ring structure. Divalent heteroatom-containing groups may be present between carbon atoms forming the skeleton of the cyclic or chain structure, and some or all of the hydrogen atoms on the carbon atoms of the cyclic or chain structure may be substituted with other substituents.

[0078] As a divalent heteroatom-containing group, L in formula (1) above is an example. α The divalent heteroatom-containing group shown can be suitably adopted.

[0079] A substituent that replaces some or all of the hydrogen atoms on the carbon atoms of the above cyclic or chain structure is R in formula (1) above. ａ The substituents shown in can be suitably adopted.

[0080] In the above-described first acid generation structure, the first organic acid anion preferably has a sulfonic acid anion as the acid anion portion, and an electron-withdrawing group is preferably bonded to the carbon atom at the α or β position relative to the sulfur atom in the sulfonic acid anion. This allows the first acid generation structure to efficiently exhibit the above-described function. Examples of electron-withdrawing groups include fluorine atoms, fluorinated hydrocarbon groups, nitro groups, and cyano groups. As the fluorinated hydrocarbon group, a perfluoroalkyl group having 1 to 5 carbon atoms is preferred.

[0081] Examples of the first onium cation mentioned above include radiodegradable onium cations. Examples of radiodegradable onium cations include sulfonium cations, tetrahydrothiophenium cations, and iodonium cations. Among these, sulfonium cations or iodonium cations are preferred, and sulfonium cations are more preferred.

[0082] The first onium cation in structural unit (II) is preferably a halogen-containing onium cation having a fluoro group or an iodine group. The halogen-containing onium cation is preferably a halogen-containing aromatic ring structure. The halogen-containing aromatic ring structure is a structure in which some or all of the hydrogen atoms in the aromatic ring are replaced by a fluoro group or an iodine group. The aromatic ring in the halogen-containing aromatic ring structure is Ar of formula (1) above. １ The aromatic ring in this material can be suitably employed. This increases the radiation absorption efficiency, thereby improving sensitivity.

[0083] The structural unit (II) can efficiently perform the above-mentioned functions by combining the above-mentioned structures.

[0084] The structural unit (II) is preferably a structural unit represented by the following formula (a1) (hereinafter also referred to as "structural unit (II-1)").

[0085]

[0086] In the formula, R Ｖ This is a hydrogen atom or a methyl group. V １ This is a single bond or an ester group. V ２ This is a linear, branched, or cyclic alkylene group having 1 to 12 carbon atoms, a cycloalkylene group having 3 to 12 carbon atoms, or an arylene group having 6 to 10 carbon atoms, or a combination thereof, or an amide bond, and a portion of the methylene groups constituting the alkylene group, the cycloalkylene group, or the arylene group may be substituted with an ether group, an ester group, or a lactone ring-containing group. ３ This is a single bond, an ether group, an ester group, or a linear or branched alkylene group having 1 to 12 carbon atoms, a cyclic cycloalkylene group having 3 to 12 carbon atoms, or a combination thereof, and a portion of the methylene groups constituting the alkylene group or the cycloalkylene group may be substituted with an ether group or an ester group. ２ and V ３Some or all of the hydrogen atoms in the compound may be substituted with a monovalent hydrocarbon group having 1 to 20 carbon atoms, which may contain a hydroxyl group, a carboxyl group, a halogen atom, an oxo group, a cyano group, an amide group, a nitro group, or a heteroatom. Rf １ ~Rf ２ Each of these is independently a hydrogen atom, a fluorine atom, or a trifluoromethyl group, but at least one is a fluorine atom or a fluorinated hydrocarbon group. kk is an integer from 1 to 4. w is independently a substructure (w) represented by the above formula (w1) or (w2). L ａ１ and L ａ２ These are, independently, a single bond, an alkylene group having 1 to 12 carbon atoms, an ether group, an ester group, a thioether group, or a combination thereof. w, L ａ１ and L ａ２ If there are multiple instances, there are multiple instances of w, L ａ１ and L ａ２ They are either identical or different. na and nb are independent integers between 0 and 3, except that na + nb is 1 or greater. Z １ ＋ This is a sulfonium cation or an iodonium cation.

[0087] V ２ and V ３ The C1-C20 monovalent hydrocarbon group in this is preferably a C1-C12 alkyl group, a C3-C12 cycloalkyl group, or a C6-C20 aryl group. Some or all of the hydrogen atoms in these groups may be substituted with heteroatom-containing groups such as hydroxyl groups, carboxyl groups, halogen atoms, oxo groups, cyano groups, amide groups, nitro groups, sultone groups, sulfone groups, or sulfonium salt-containing groups, alkoxy groups, or alkoxycarbonyl groups. Some of the methylene groups constituting these groups may be substituted with ether groups, ester groups, carbonyl groups, carbonate groups, or sulfonic acid ester groups.

[0088] V ２ It is preferable that it is an arylene group having 6 to 10 carbon atoms. ａ１ and L ａ２It is preferable that the group is a combination of an alkylene group having 1 to 12 carbon atoms and an ether group. Na is preferably 1 or 2. NB is preferably 0 or 1.

[0089] The structural unit (II-1) is preferably a structural unit represented by the following formula (a1-1).

[0090]

[0091] In the formula, R Ｖ , Rf １ ~Rf ２ , V １ ,kk,w,L ａ１ na and Z １ ＋ This is equivalent to the above formula (a1). R ４８ n is a linear, branched, or cyclic alkyl group having 1 to 4 carbon atoms, a halogen atom, a hydroxyl group, a linear, branched, or cyclic alkoxy group having 1 to 4 carbon atoms, or a linear, branched, or cyclic alkoxycarbonyl group having 2 to 5 carbon atoms. n is an integer from 0 to 3.

[0092] The first organic acid anion of the monomer that gives structural unit (II) (including structural unit (II-1)) is shown below, but is not limited to these structures. In the following, w-L in formula (a1) above ａ１ -or w-L ａ１ -The corresponding structure is a hydrogen atom or R in formula (1) above. ａ Substitutions may be made with the substituents shown in [reference].

[0093]

[0094]

[0095]

[0096] In the above formula, R Ｖ This is equivalent to equation (a1) above.

[0097] Z in the above formula (a1) １ ＋ Preferably, it is a sulfonium cation represented by the following formula (Q-1).

[0098]

[0099] In the above formula (Q-1), Ra1 and Ra2 each independently represent substituents. n1 represents an integer from 0 to 5, and if n1 is 2 or greater, multiple Ra1s may be the same or different. n2 represents an integer from 0 to 5, and if n2 is 2 or greater, multiple Ra2s may be the same or different. Ra3 represents a substituent. n3 represents an integer from 0 to 5, and if n3 is 2 or greater, multiple Ra3s may be the same or different. Ra1 and Ra2 may be linked to each other to form a ring. If n1 is 2 or greater, multiple Ra1s may be linked to each other to form a ring. If n2 is 2 or greater, multiple Ra2s may be linked to each other to form a ring.

[0100] In the above formula (Q-1), w is a substructure (w) that is independently represented by the above formula (w1) or (w2). ｑ１ , L ｑ２ and L ｑ３ These are, independently, a single bond, an ether group, an ester group, or a thioether group. w, L ｑ１ , L ｑ２ and L ｑ３ If there are multiple instances, there are multiple instances of w, L ｑ１ , L ｑ２ and L ｑ３ They are either identical or different from each other. qa, qb, and qc are each independent integers between 0 and 3.

[0101] Preferred substituents represented by Ra1, Ra2, and Ra3 are alkyl groups, cycloalkyl groups, alkoxy groups, cycloalkyloxy groups, alkoxycarbonyl groups, alkylsulfonyl groups, hydroxyl groups, halogen atoms, and halogenated hydrocarbon groups.

[0102] The alkyl groups Ra1 and Ra2 may be linear or branched alkyl groups. Preferably, these alkyl groups have 1 to 10 carbon atoms, and examples include methyl, ethyl, n-propyl, i-propyl, n-butyl, 2-methylpropyl, 1-methylpropyl, t-butyl, n-pentyl, neopentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl groups. Of these, methyl, ethyl, n-butyl, and t-butyl groups are particularly preferred.

[0103] Examples of cycloalkyl groups for Ra1 and Ra2 include monocyclic or polycyclic cycloalkyl groups (preferably cycloalkyl groups having 3 to 20 carbon atoms), such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclododecanyl, cyclopentenyl, cyclohexenyl, and cyclooctadienyl groups. Of these, cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups are particularly preferred.

[0104] Examples of the alkyl groups of the alkoxy groups of Ra1 and Ra2 include those previously listed as alkyl groups of Ra1 and Ra2. Methoxy, ethoxy, n-propoxy, and n-butoxy groups are particularly preferred as alkoxy groups.

[0105] Examples of the cycloalkyl group portions of Ra1 and Ra2 include those previously listed as cycloalkyl groups of Ra1 and Ra2. Cyclopentyloxy and cyclohexyloxy groups are particularly preferred as these cycloalkyl groups.

[0106] Examples of the alkoxy carbonyl groups of Ra1 and Ra2 include those previously listed as alkoxy groups of Ra1 and Ra2. Methoxycarbonyl groups, ethoxycarbonyl groups, and n-butoxycarbonyl groups are particularly preferred as alkoxycarbonyl groups.

[0107] Examples of the alkyl group portion of the alkylsulfonyl groups of Ra1 and Ra2 include those previously listed as alkyl groups of Ra1 and Ra2. Similarly, examples of the cycloalkyl group portion of the cycloalkylsulfonyl groups of Ra1 and Ra2 include those previously listed as cycloalkyl groups of Ra1 and Ra2. Among these alkylsulfonyl groups or cycloalkylsulfonyl groups, methanesulfonyl, ethanesulfonyl, n-propanesulfonyl, n-butanesulfonyl, cyclopentanesulfonyl, and cyclohexanesulfonyl groups are particularly preferred.

[0108] Each of the Ra1 and Ra2 groups may have further substituents. Examples of such substituents include halogen atoms such as fluorine atoms (preferably fluorine atoms), hydroxyl groups, carboxyl groups, cyano groups, nitro groups, alkoxy groups, cycloalkyloxy groups, alkoxyalkyl groups, cycloalkyloxyalkyl groups, alkoxycarbonyl groups, cycloalkyloxycarbonyl groups, alkoxycarbonyloxy groups, and cycloalkyloxycarbonyloxy groups.

[0109] Examples of halogen atoms for Ra1 and Ra2 include fluorine, chlorine, bromine, and iodine atoms, with fluorine and iodine atoms being preferred.

[0110] As the halogenated hydrocarbon groups of Ra1 and Ra2, halogenated alkyl groups are preferred. The alkyl groups and halogen atoms constituting the halogenated alkyl groups are the same as those described above. Among these, fluorinated alkyl groups are preferred, and CF ３ This is preferable.

[0111] As described above, Ra1 and Ra2 may be linked to each other to form a ring (i.e., a heterocycle containing a sulfur atom). In this case, it is preferable that Ra1 and Ra2 are linked to each other to form a single bond or a divalent linking group. Examples of divalent linking groups include -COO-, -OCO-, -CO-, -O-, -S-, -SO-, and -SO ２-, alkylene group, cycloalkylene group, alkenylene group, or combination of two or more of these, preferably with a total carbon number of 20 or less. When Ra1 and Ra2 are linked to each other to form a ring, Ra1 and Ra2 are linked to each other as -COO-, -OCO-, -CO-, -O-, -S-, -SO-, -SO ２ - or single bond formation is preferable. Among these, -O-, -S-, or single bond formation is more preferable, and single bond formation is particularly preferable. Furthermore, when n1 is 2 or more, multiple Ra1s may be linked to each other to form a ring, and when n2 is 2 or more, multiple Ra2s may be linked to each other to form a ring. An example of such a configuration is one in which two Ra1s are linked to each other and form a naphthalene ring together with the benzene ring to which they are linked.

[0112] Ra3 is preferably a fluorine atom, a group having one or more fluorine atoms, or an iodine atom. Examples of groups having fluorine atoms include alkyl groups, cycloalkyl groups, alkoxy groups, cycloalkyloxy groups, alkoxycarbonyl groups, and alkylsulfonyl groups, which are substituted with fluorine atoms as Ra1 and Ra2. Among these, fluorinated alkyl groups are particularly preferred, and CF ３ , C ２ F ５ , C ３ F ７ , C ４ F ９ , C ５ F １１ , C ６ F １３ , C ７ F １５ , C ８ F １７ ,CH ２ CF ３ ,CH ２ CH ２ CF ３ ,CH ２ C ２ F ５ ,CH ２ CH ２ C ２ F ５ ,CH ２ C ３ F７ ,CH ２ CH ２ C ３ F ７ ,CH ２ C ４ F ９ and CH ２ CH ２ C ４ F ９ The following can be more preferably listed: CF ３ The following can be particularly preferred.

[0113] Ra3 is a fluorine atom, an iodine atom, or CF ３ It is preferable that it be a fluorine atom or an iodine atom.

[0114] n1 and n2 are each independently preferably integers between 0 and 3, and preferably integers between 0 and 2.

[0115] n3 is preferably an integer between 1 and 3, and more preferably 1 or 2.

[0116] (n1 + n2 + n3) is preferably an integer from 1 to 15, more preferably an integer from 1 to 9, even more preferably an integer from 2 to 6, and particularly preferably an integer from 3 to 6. When (n1 + n2 + n3) is 1, n3 = 1 and Ra3 is a fluorine atom, an iodine atom, or CF ３ It is preferable that (n1 + n2 + n3) is 2, then n1 = n3 = 1 and Ra1 and Ra3 are each independently a fluorine atom, an iodine atom, or CF ３ The combinations are as follows, and n3=2 and Ra3 is a fluorine atom, an iodine atom or CF ３ The following combinations are preferred. When (n1 + n2 + n3) is 3, n1 = n2 = n3 = 1 and Ra1 to Ra3 are each independently a fluorine atom, an iodine atom, or CF ３ The following combinations are preferred. When (n1 + n2 + n3) is 4, n1 = n3 = 2 and Ra1 and Ra3 are each independently a fluorine atom, an iodine atom or CF ３ The following combinations are preferred. When (n1 + n2 + n3) is 5, n1 = n2 = 1 and n3 = 3, and Ra1 to Ra3 are each independently a fluorine atom, an iodine atom, or CF ３The combination is such that n1=n2=2 and n3=1, and Ra1 to Ra3 are each independently a fluorine atom, an iodine atom, or CF ３ The combinations are such that n3=5 and each Ra3 is independently a fluorine atom, an iodine atom, or CF ３ The following combinations are preferred. When (n1 + n2 + n3) is 6, n1 = n2 = n3 = 2 and Ra1 to Ra3 are each independently a fluorine atom, an iodine atom, or CF ３ The combination is preferable.

[0117] Specific examples of sulfonium cations represented by the above formula (Q-1) include the following: fluorine atoms and iodine atoms in the sulfonium cations listed below, and w-L in the above formula (a1). ａ１ -or w-L ａ１ -The corresponding structure is a hydrogen atom or R in formula (1) above. ａ It may be substituted with the substituents shown in [reference].

[0118]

[0119]

[0120]

[0121]

[0122]

[0123] The first onium cation of structural unit (II) may be a diaryliodonium cation. The diaryliodonium cation preferably has one or more fluorine or iodine atoms. At least one of the aryl groups of the iodonium cation preferably has the halogen-containing aromatic ring structure or the substructure (w). A phenyl group is preferred as the aryl group.

[0124] In this configuration, a first onium cation is bonded to the main chain as the side chain structure of the base polymer, and a first organic acid anion is ionically bonded to the first onium cation as its counterion. In this case, the first onium cation is bonded to the main chain via a divalent linking group or a single bond, and V in formula (a1) is formed. ２ From SO ３ - It is preferable that the structure up to this point is ionically bonded to the first onium cation as a counterion. The divalent linking group is L of formula (1) above. α The group represented by , the above-mentioned divalent heteroatom-containing group, or a combination thereof can be suitably adopted.

[0125] When the base polymer has structural unit (II), the lower limit of the content of structural unit (II) (total content if multiple types are included) is preferably 1 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%. By setting the content of structural unit (II) within the above range, the function as an acid-generating structure can be fully exhibited, and the above resist properties can be achieved.

[0126] The monomer that gives structural unit (II-1) can be synthesized, for example, by the same method as the sulfonium salt having a polymerizable anion described in Japanese Patent Publication No. 5201363.

[0127] (Structural Unit (III)) The base polymer may also contain a structural unit (III) which has a second organic acid anion and a second onium cation, and which includes a second acid generation structure that generates an acid that does not dissociate the acid-dissociable group upon exposure. Preferably, at least one selected from the group consisting of the second organic acid anion and the second onium cation has the above substructure (w), and more preferably, the second organic acid anion has the above substructure (w).

[0128] The onium salt structure formed by the second organic acid anion and the second onium cation (i.e., the second acid generation structure) functions as an acid diffusion control structure. Specifically, under pattern formation conditions using the above-mentioned radiation-sensitive composition, the second acid generation structure substantially prevents the dissociation of the acid-dissociable group of structural unit (I), and has the function of suppressing the diffusion of acid generated from the first acid generation structure or the radiation-sensitive acid generator (if present) in the unexposed areas by salt exchange. The acid generated from the second acid generation structure can be said to be a relatively weaker acid (an acid with a high pKa) than the acid generated from the first acid generation structure. Whether the onium salt structure functions as a radiation-sensitive acid generation structure or an acid diffusion control structure depends on the energy required to dissociate the acid-dissociable group of the base polymer, and the acidity of the onium salt structure or the generated acid.

[0129] The form in which the second organic acid anion and the second onium cation are contained in the structural unit (III) of the base polymer is not particularly limited, and the base polymer may have the second organic acid anion as a side chain portion, or it may have the second onium cation as a side chain portion. Having it as a side chain portion means that the corresponding second organic acid anion or second onium cation is bonded (covalently bonded) to the main chain as a side chain structure of the base polymer. When the second organic acid anion is bonded to the main chain as a side chain structure of the base polymer, the second onium cation is ionically bonded to the second organic acid anion as its counterion. On the other hand, when the second onium cation is bonded to the main chain as a side chain structure of the base polymer, the second organic acid anion is ionically bonded to the second onium cation as its counterion. From the viewpoint of development contrast, it is preferable that the base polymer has the second organic acid anion as a side chain portion.

[0130] The above-mentioned second organic acid anion preferably has a sulfonic acid anion or a carboxylic acid anion as the acid anion portion, and more preferably has a carboxylic acid anion. However, when the above-mentioned second organic acid anion has the above-mentioned sulfonic acid anion, no electron-withdrawing group is bonded to either the α-position or the β-position carbon atom of the sulfur atom in the above-mentioned sulfonic acid anion. Examples of electron-withdrawing groups include electron-withdrawing groups that the above-mentioned first organic acid anion may have in the above-mentioned first acid generation structure. The acid generated by exposure is a carboxylic acid or sulfonic acid, corresponding to the above-mentioned acid anion portion.

[0131] The above-mentioned second organic acid anion preferably includes -O-, -CO-, a cyclic structure, or a combination thereof as a structure other than the acid anion portion. The structure shown for the above-mentioned first organic acid anion can be suitably adopted as such a structure.

[0132] The above-mentioned second organic acid anion preferably has a hydroxyl group.

[0133] Examples of the second onium cation mentioned above include radiodegradable or non-radiodegradable onium cations. Examples of radiodegradable or non-radiodegradable onium cations include sulfonium cations, tetrahydrothiophenium cations, iodonium cations, and ammonium cations. Among these, sulfonium cations or iodonium cations are preferred, and sulfonium cations are more preferred.

[0134] The second onium cation in structural unit (III) preferably has the halogen-containing aromatic ring structure described above. This increases the radiation absorption efficiency, thereby improving sensitivity.

[0135] The structural unit (III) can efficiently perform the above-mentioned functions by combining the above-mentioned structures.

[0136] The structural unit (III) is preferably a structural unit represented by the following formula (p1) (hereinafter also referred to as "structural unit (III-1)").

[0137]

[0138] In formula (p1), R A This is either a hydrogen atom or a methyl group.

[0139] In formula (p1), X 1 These are single bonds, ester bonds, ether bonds, amide bonds, arylene groups, or combinations thereof. Examples of arylene groups include phenylene groups and naphthylene groups.

[0140] In formula (p1), X ２ This is a single bond, a saturated hydrocarbylene group or arylene group having 1 to 12 carbon atoms, or a combination thereof, and the saturated hydrocarbylene group may include an ether bond, an ester bond, an amide bond, a lactone ring, or a sultone ring. ２ The hydrocarbylene group represented by can be linear, branched, or cyclic, and specific examples include methylene group, ethane-1,1-diyl group, ethane-1,2-diyl group, propane-1,2-diyl group, propane-1,3-diyl group, propane-2,2-diyl group, butane-1,2-diyl group, butane-1,3-diyl group, butane-1,4-diyl group, butane-2,2-diyl group, butane-2,3-diyl group, 2-methylpropane-1,3- Examples include C1-C12 alkanediyl groups such as diyl groups, pentane-1,5-diyl groups, hexane-1,6-diyl groups, heptane-1,7-diyl groups, octane-1,8-diyl groups, nonane-1,9-diyl groups, and decane-1,10-diyl groups; C3-C12 cyclic saturated hydrocarbylene groups such as cyclopentanediyl groups, cyclohexanediyl groups, norbornanediyl groups, and adamantanediyl groups; and groups obtained by combining these.

[0141] In formula (p1), X 1 ~X ２ Some or all of the hydrogen atoms in may be substituted with substituents. Examples of substituents include R in formula (1) above. ａ The substituents shown in can be suitably adopted.

[0142] In formula (p1), w is a substructure (w) that is independently represented by formula (w1) or (w2) above. ｐ１and L ｐ２ These are, independently, a single bond, an alkylene group having 1 to 12 carbon atoms, an ether group, an ester group, a thioether group, or a combination thereof. w, L ｐ１ and L ｐ２ If there are multiple instances, there are multiple instances of w, L ｐ１ and L ｐ２ They are either identical or different. pa and pb are independent integers between 0 and 3, except that pa + pb is 1 or greater. 1 ~X ２ If the compound has a phenylene group, it is preferable that some or all of the hydrogen atoms of the phenylene group are substituted with a substructure (w) represented by the above formula (w1) or (w2).

[0143] In formula (p1), Z ２ ＋ This is Z in the above formula (a1). １ ＋ It is synonymous with [the above].

[0144] In the above formula (p1), an iodonium cation can also be used as the second onium cation. The diaryliodonium cation shown as the onium cation of structural unit (II-1) can be suitably adopted as the iodonium cation.

[0145] The second organic acid anion of the monomer that gives structural unit (III) can be, but is not limited to, the following structures. ａ１ -or w-L ａ１ -The corresponding structure is a hydrogen atom or R in formula (1) above. ａ It may be substituted with substituents shown in the following formula. Ａ The same applies as described above. It is preferable that the second organic acid anion has a carboxylic acid anion and a hydroxyl group.

[0146]

[0147]

[0148]

[0149] As the second onium cation of structural unit (III), the sulfonium cation represented by the above formula (Q-1) can be suitably adopted.

[0150] In this configuration, a secondary onium cation is bonded to the main chain as the side chain structure of the base polymer, and a secondary organic acid anion is ionically bonded to the secondary onium cation as its counterion. In this case, the secondary onium cation is bonded to the main chain via a divalent linking group or a single bond, and X in formula (p1) above is formed. １ From COO - It is preferable that the structure up to this point is ionically bonded to the second onium cation as a counterion. The divalent linking group is the L of formula (1) above. α A group represented by or the above-mentioned divalent heteroatom-containing group can be suitably adopted.

[0151] When the base polymer contains structural unit (III), the lower limit of the content of structural unit (III) (or the total content if multiple types are included) is preferably 1 mol%, more preferably 3 mol%, and even more preferably 4 mol%, relative to the total amount of the monomer that provides structural unit (II) and the radiation-sensitive acid generator (if both are included). The upper limit of the above content is preferably 30 mol%, more preferably 20 mol%, and even more preferably 10 mol%. When an optional component, such as an acid diffusion control agent, is included, the total amount of the monomer that provides structural unit (III) and the acid diffusion control agent should be within the above range. By setting the content of structural unit (III) within the above range, the function as an acid diffusion control structure can be fully exhibited.

[0152] (Structural Unit (IV)) Structural unit (IV) is a structural unit having a phenolic hydroxyl group (excluding structures corresponding to structural units (I) to (III)). By including structural unit (IV) in the polymer, the solubility in the developer can be adjusted more appropriately, and as a result, the sensitivity of the above-mentioned radiation-sensitive composition can be further improved. Furthermore, when KrF excimer laser light, EUV, electron beams, etc. are used as the radiation irradiated in the exposure step in the resist pattern formation method, structural unit (IV) contributes to improving etching resistance and improving the difference in developer solubility between the exposed and unexposed areas (dissolution contrast). In particular, it can be suitably applied to pattern formation using exposure with radiation of wavelength 50 nm or less, such as electron beams and EUV. Structural unit (IV) is preferably represented by the following formula (2).

[0153] (In the above formula (2), R β L is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ＣＡ This is a single bond, -COO- ＊ , -O- or -CONH- ＊ This is the case. * 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.)

[0154] The above R β From the viewpoint of copolymerization of the monomer that gives structural unit (IV), it is preferable that it be a hydrogen atom or a methyl group.

[0155] L ＣＡ For example, a single bond or -COO- ＊ It is preferable.

[0156] R １０２ The halogen atom, alkyl group, alkoxycarbonyloxy group, acyl group, or acyloxy group in formula (1) above is R ａ The groups listed below can be suitably adopted as substituents. １０２ In this mixture, iodine or fluorine atoms are preferred as halogen atoms, with iodine atoms being more preferred.

[0157] The above n ３ As such, 0 or 1 is more preferable, and 0 is even more preferable. ３ If the value is 1 or greater, then -OH and -R in formula (2) above. １０２ Each of these may be bonded to any of the multiple benzene rings that are condensed.

[0158] The above m ３ Preferably, the integer is between 1 and 3, and more preferably 1 or 2.

[0159] The above m ４ Preferably, the integer is between 0 and 3, and more preferably between 0 and 2.

[0160] The above structural unit (IV) is preferably a structural unit represented by the following formulas (2-1) to (2-24) (hereinafter also referred to as "structural unit (2-1) to structural unit (2-24)").

[0161]

[0162]

[0163] In the above equations (2-1) to (2-24), R β This is the same as equation (2) above.

[0164] When the base polymer has structural units (IV), the lower limit of the content of structural units (IV) (total if there are multiple types of structural units (IV)) is preferably 10 mol%, more preferably 20 mol%, and even more preferably 30 mol%, relative to the total structural units constituting the polymer. The upper limit of the above content is preferably 85 mol%, more preferably 75 mol%, and even more preferably 70 mol%. By setting the content of structural units (IV) within the above range, the radiation-sensitive composition can achieve further improvements in sensitivity and development contrast.

[0165] (Structural Unit (V)) Structural unit (V) 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 (V), 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. In addition, the adhesion between the resist pattern formed from the base polymer and the substrate can be improved.

[0166] Among these, structural units (V) that include a lactone structure are preferred, and structural units that include a γ-butyrolactone structure, norbornane lactone structure, or adamantane lactone structure are more preferred.

[0167] When the base polymer has structural units (V), the lower limit of the content of structural units (V) (total content if multiple types are included) is preferably 5 mol%, more preferably 10 mol%, and even more preferably 15 mol%, relative to the total structural units constituting the base polymer. The upper limit of the above content is preferably 70 mol%, more preferably 60 mol%, and even more preferably 55 mol%. By setting the content of structural units (V) 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.

[0168] (Structural Unit (VI)) Structural unit (VI) is a structural unit containing a polar group (excluding those corresponding to structural units (I) to (V)). The solubility of the base polymer in the developer can be adjusted by further containing structural unit (VI). Examples of the above polar groups include hydroxyl groups, carboxyl groups, cyano groups, nitro groups, sulfo groups, and sulfonamide groups. Among these, hydroxyl groups and carboxyl groups are preferred, and hydroxyl groups are more preferred.

[0169] Examples of structural units (VI) include structural units represented by the following formula.

[0170]

[0171]

[0172] In the above formula, R Ｋ This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0173] When the base polymer has structural units (VI) having the polar group described above, the lower limit of the content of structural units (VI) (total content if multiple types are included) is preferably 5 mol%, more preferably 10 mol%, and even more preferably 15 mol%, relative to the total structural units constituting the base polymer. The upper limit of the above content is preferably 40 mol%, more preferably 35 mol%, and even more preferably 30 mol%. By setting the content of structural units (VI) within the above range, the solubility of the base polymer in the developer can be efficiently adjusted.

[0174] (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.

[0175] The molecular weight of the base polymer is not particularly limited, but the lower limit of the weight-average molecular weight (Mw) in polystyrene terms, as 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 20,000, more preferably 16,000, and even more preferably 12,000. By setting the Mw of the base polymer within the above range, the resulting resist film can exhibit good heat resistance and developability.

[0176] 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.

[0177] The methods for measuring Mw and Mn of polymers in this specification are as described in the examples.

[0178] The lower limit of the base polymer content is preferably 40% by mass, more preferably 50% by mass, and even more preferably 60% by mass, relative to the total solid content of the radiation-sensitive composition. The upper limit of the above content is preferably 95% by mass, and more preferably 90% by mass.

[0179] (Other Polymers) The radiation-sensitive composition of this embodiment may also contain, as other polymers, polymers with a higher mass content of fluorine atoms than the base polymer (hereinafter also referred to as "high-fluorine content polymers"). When the radiation-sensitive composition contains high-fluorine content polymers, they can be unevenly distributed on the surface of the resist film relative to the base polymer, thereby improving the water repellency of the surface of the resist film during immersion exposure, and controlling the surface modification of the resist film and the distribution of the internal composition during EUV exposure. The radiation-sensitive composition may contain one or more high-fluorine content polymers.

[0180] When a high-fluorine-content polymer has a structural unit (VIII) containing a monovalent or divalent fluorinated hydrocarbon group (however, this is different from structural units (II), (III), and (VI)), the content of structural unit (VIII) is preferably 40 mol%, more preferably 50 mol%, and even more preferably 55 mol%, relative to the total structural units constituting the high-fluorine-content polymer. Furthermore, the upper limit of the above content is preferably 90 mol%, more preferably 85 mol%, and even more preferably 80 mol%. By setting the content of structural unit (VIII) within the above range, it is possible to improve the water repellency and surface modification properties of the resist film, as well as improve solubility in alkaline developers, and efficiently suppress the occurrence of development defects.

[0181] [Other structural units] High-fluorine polymers may also contain structural units other than those listed above, such as structural unit (I) and structural unit (VI) in the base polymer.

[0182] The lower limit of Mw for the high-fluorine-content polymer is preferably 2,000, more preferably 4,000, and even more preferably 6,000. The upper limit of Mw is preferably 20,000, more preferably 15,000, and even more preferably 10,000.

[0183] The lower limit of Mw / Mn for high-fluorine-content polymers is usually 1, and 1.1 is more preferred. The upper limit of Mw / Mn is usually 5, 3 is preferred, and 2 is more preferred.

[0184] If the radiation-sensitive composition contains a high-fluorine-content polymer, the content of the high-fluorine-content polymer is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1 part by mass or more, and particularly preferably 1.5 parts by mass or more, per 100 parts by mass of the base polymer. Furthermore, it is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 8 parts by mass or less, and particularly preferably 5 parts by mass or less.

[0185] (Method for synthesizing high-fluorine content polymers) High-fluorine content polymers can be synthesized by the same method as the base polymer synthesis method described above.

[0186] <Onium Salt Compounds> The radiation-sensitive composition may contain onium salt compounds. If the composition contains onium salt compounds, the onium salt compounds include at least one onium salt compound selected from the group consisting of onium salt compound (1) as a radiation-sensitive acid generator and onium salt compound (2) as an acid diffusion control agent. If the base polymer contains structural unit (II), the inclusion of onium salt compound (1) in the composition is optional, and the inclusion of onium salt compound (2) is preferred. If the base polymer contains structural unit (III), the composition is preferably inclusion of onium salt compound (1), and the inclusion of onium salt compound (2) is optional. If the base polymer contains structural units (II) and (III), the inclusion of onium salt compounds (1) and (2) in the composition is optional, respectively. If the base polymer does not contain structural unit (II), the composition is preferably inclusion of onium salt compound (1) and onium salt compound (2). If the base polymer does not contain structural unit (III), the composition preferably contains onium salt compound (1) and onium salt compound (2).

[0187] (Onium salt compound (1)) Onium salt compound (1) as a radiation-sensitive acid generator contains a third organic acid anion and a third onium cation, forming an onium salt structure. A 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. Onium salt compound (1) as a 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 is different from a radiation-sensitive acid-generating structure in which the first organic acid anion or the first onium cation is bonded (covalently) to the main chain as a side chain structure of the base polymer, as in structural unit (II) in the base polymer.

[0188] It is preferable that at least one selected from the group consisting of the above-mentioned third organic acid anion and third onium cation has the above-mentioned substructure (w), and it is more preferable that the above-mentioned third organic acid anion has the above-mentioned substructure (w).

[0189] The above-mentioned third organic acid anion preferably has at least one selected from the group consisting of sulfonic acid anions and sulfonimide anions as the acid anion portion, and more preferably has a sulfonic acid anion. As the acid generated by exposure, sulfonic acid and sulfonimide can be given, corresponding to the above-mentioned acid anion portion.

[0190] The above-mentioned third organic acid anion preferably includes -O-, -CO-, a cyclic structure, or a combination thereof as a structure other than the acid anion portion. This combination also includes structures (heterocyclic structures) in which -O- or -CO- are incorporated as ring-forming parts within the cyclic structure. As the above-mentioned cyclic structure, the cyclic structure shown in structural unit (II) above can be suitably adopted.

[0191] In the above-described third acid generation structure, the third organic acid anion preferably has a sulfonic acid anion as the acid anion portion, and an electron-withdrawing group is bonded to the carbon atom at the α or β position relative to the sulfur atom in the sulfonic acid anion. This allows the third acid generation structure to efficiently perform the above-described function. As the electron-withdrawing group, the electron-withdrawing group shown in the above-described structural unit (II) can be suitably adopted.

[0192] The above-mentioned third onium cation can be suitably adopted. In particular, the above-mentioned third onium cation is preferably a sulfonium cation or an iodonium cation.

[0193] The structure of the third organic acid anion in the onium salt compound (1) is V in the above formula (a1) of the structural unit (II) of the base polymer. ２ From SO ３ - In addition to the structure represented by the following formula (a11) corresponding to the above, a structure in which the above substructure (w) is introduced into a conventionally known anionic structure can be suitably adopted.

[0194]

[0195] In the formula, V ２１This is a linear, branched, or cyclic alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or an aryl group having 6 to 10 carbon atoms, or a combination thereof, and some of the methylene groups constituting the alkyl group, cycloalkyl group, or aryl group may be substituted with an ether group, an ester group, or a lactone ring-containing group. ３ , Rf １ ~Rf ２ ,kk,w,L ａ１ , L ａ２ na and nb are equivalent to the above formula (a1). V ２１ and V ３ Some or all of the hydrogen atoms in it are V in formula (a1) above ２ and V ３ It may be substituted with substituents that it may have.

[0196] The third organic acid anion of the onium salt compound (1) may be, but is not limited to, the structures shown below. In the following formula, w-L in formula (a11) above ａ１ -or w-L ａ２ -The corresponding structure is a hydrogen atom or R in formula (1) above. ａ Substitutions may be made with the substituents shown in [reference].

[0197]

[0198]

[0199]

[0200] The structure of the third onium cation in the onium salt compound (1) can preferably be the structure of the first onium cation of structural unit (II) in the base polymer.

[0201] The onium salt compound (1) used as a radiation-sensitive acid generator can also be synthesized by known methods, particularly by salt exchange reactions. Known radiation-sensitive acid generators can also be used, as long as they do not impair the effects of the present invention.

[0202] These onium salt compounds (1) may be used individually or in combination of two or more. When the radiation-sensitive composition contains onium salt compounds (1), the lower limit of the onium salt compound (1) content (total in the case of multiple types) is preferably 10 parts by mass, more preferably 20 parts by mass, and even more preferably 25 parts by mass, per 100 parts by mass of the base polymer. The upper limit of the above content is preferably 60 parts by mass, more preferably 50 parts by mass, and even more preferably 40 parts by mass. This allows for excellent sensitivity during resist pattern formation.

[0203] (Onium salt compound (2)) The radiation-sensitive composition may contain an onium salt compound (2) as an acid diffusion control agent. The onium salt compound (2) contains a fourth organic acid anion and a fourth onium cation, and upon irradiation with radiation, generates an acid with a higher pKa than the acid generated from the first acid generation structure of the structural unit (II) and the onium salt compound (1). As an acid diffusion control agent, the onium salt compound (2) has the function of substantially preventing the dissociation of the acid-dissociable groups of the base polymer under pattern-forming conditions using the radiation-sensitive composition, and suppressing the diffusion of the acid generated from the first acid generation structure of the structural unit (II) and the onium salt compound (1) in the unexposed areas by salt exchange.

[0204] By including the onium salt compound (2) as the acid diffusion control agent in the radiation-sensitive composition, acid diffusion in unexposed areas can be suppressed, and a resist pattern with superior LWR and development contrast can be formed.

[0205] It is preferable that at least one selected from the group consisting of the above-mentioned fourth organic acid anion and fourth onium cation has the above-mentioned substructure (w), and it is more preferable that the above-mentioned fourth organic acid anion has the above-mentioned substructure (w).

[0206] Although the structure of the above-mentioned fourth organic acid anion is not specified, it is preferable that it includes -O-, -CO-, a cyclic structure, or a combination thereof. As the cyclic structure, the cyclic structure of the above-mentioned first organic acid anion of structural unit (II) of the base polymer can be suitably adopted.

[0207] In the onium salt compound (2), it is preferable that the fourth organic anion has a sulfonic acid anion or a carboxylic acid anion as the acid anion portion (however, if the fourth organic acid anion has a sulfonic acid anion, then no electron-withdrawing group is bonded to either the α-position or the β-position carbon atom of the sulfur atom in the sulfonic acid anion). This allows the onium salt compound (2) to efficiently exhibit the above function as an acid diffusion control agent.

[0208] The structure of the fourth organic acid anion in the onium salt compound (2) is X in the above formula (p1) of the structural unit (III) of the base polymer. １ From COO - In addition to the structure represented by the following formula (p11) corresponding to the above, a structure in which the above substructure (w) is introduced into a conventionally known anionic structure can be suitably adopted.

[0209]

[0210] In formula (p11), X １１ X is a single bond, ester bond, ether bond, amide bond, aryl group, or a combination thereof. ２ , w, L ｐ１ , L ｐ２ , pa and pb are equivalent to the above formula (p1). X １１ and X ２ Some or all of the hydrogen atoms in it are V in formula (a1) above ２ and V ３ It may be substituted with substituents that it may have.

[0211] The fourth organic acid anion of the onium salt compound (2) can be, but is not limited to, the structures shown below. In the following formula, w-L in formula (p11) above ｐ１ -or w-L ｐ２ -The corresponding structure is a hydrogen atom or R in formula (1) above. ａ Substitutions may be made with the substituents shown in [reference].

[0212]

[0213]

[0214]

[0215] As the fourth onium cation in the above onium salt compound (2), the structure of the first onium cation of structural unit (II) in the above base polymer can be suitably adopted.

[0216] The above onium salt compound (2) can also be synthesized by known methods, particularly by salt exchange reactions.

[0217] These onium salt compounds (2) as acid diffusion control agents may be used alone or in combination of two or more. When the radiation-sensitive composition contains onium salt compounds (2), the lower limit of the onium salt compound (2) content (total in the case of multiple types) is preferably 10 mol%, more preferably 30 mol%, and even more preferably 40 mol%, relative to the total amount of monomers that give structural units (II) of the base polymer and radiation-sensitive acid generators (if both are included). The upper limit of the above content is preferably 80 mol%, more preferably 70 mol%, and even more preferably 60 mol%.

[0218] <Solvent> The radiation-sensitive composition according to this embodiment contains a solvent. The solvent is not particularly limited as long as it is capable of dissolving or dispersing the base polymer and optionally contained additives.

[0219] Examples of solvents include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

[0220] Examples of alcohol-based solvents include monoalcohol solvents having 1 to 18 carbon atoms, such as isopropanol, 4-methyl-2-pentanol, 3-methoxybutanol, 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 propylene glycol 1-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, i-propyl 2-hydroxyisobutyrate, i-butyl 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 ester solvents such as diethylene glycol acetate mono-n-butyl ether, propylene glycol acetate monomethyl ether, and dipropylene glycol acetate monomethyl ether; 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, ester solvents and ether solvents are preferred, polyhydric alcohol partial ether acetate ester solvents and polyhydric alcohol partial ether solvents are more preferred, and propylene glycol acetate monomethyl ether and propylene glycol 1-monomethyl ether are even more preferred. The radiation-sensitive composition may contain one or more solvents.

[0227] <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 accelerators, surfactants, alicyclic skeleton-containing compounds, sensitizers, etc. These other optional components may be used individually or in combination of two or more types.

[0228] <Method for preparing a radiation-sensitive composition> The above radiation-sensitive composition can be prepared, for example, by mixing a base polymer and a solvent with an onium salt compound and other optional components in a predetermined ratio, if necessary. After mixing, the above radiation-sensitive composition is preferably filtered using a filter with a pore size of approximately 0.05 μm to 0.4 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.

[0229] <Pattern Forming Method> The pattern forming method in this embodiment includes the steps of: applying the above-mentioned radiation-sensitive composition directly or indirectly to a substrate to form a resist film (1) (hereinafter also referred to as the "resist film forming step"), exposing the resist film to light (2) (hereinafter also referred to as the "exposure step"), and developing the exposed resist film with a developer (3) (hereinafter also referred to as the "development step").

[0230] According to the pattern formation method described above, high-quality resist patterns can be efficiently formed because the radiation-sensitive composition exhibits good storage stability and high sensitivity, LWR, and Min CD during pattern formation. Each step will be described below.

[0231] [Resist Film Formation Process] In this process (step (1) above), a resist film is formed using the above-mentioned radiation-sensitive composition. 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 disclosed in, for example, 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, soft baking (SB) 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. The thickness of the formed resist film is preferably 10 nm to 1,000 nm, and more preferably 10 nm to 500 nm.

[0232] [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. 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.

[0233] After the exposure described above, it is preferable to perform a post-exposure bake (PEB) to promote the dissociation of acid-dissociable groups in polymers, etc., by the acid generated from the first acid-generating structure of structural unit (II) and the onium salt compound (1) in the exposed portion of the resist film. 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 150°C being preferred. The PEB time is usually 5 seconds to 600 seconds, with 10 seconds to 300 seconds being preferred.

[0234] [Development Process] In this process (step (3) above), the resist film exposed in the exposure process, which is step (2) above, is developed with a developer. 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.

[0235] 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.

[0236] In addition, in the case of organic solvent development, examples of organic solvents include hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents, 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, ester solvents and ketone solvents are preferred. As for ester solvents, acetic acid 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 solvent 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.

[0237] 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 letting it remain 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).

[0238] Onium salt compound: The onium salt compound has an organic acid anion and an onium cation, generates acid upon exposure, and has a substructure (w) represented by the following formula (w1) or (w2). (In formula (w1), R １ , R ２ and R ３ Each of these is independently a hydrogen atom, a halogen atom, a cyano group, a nitro group, or a monovalent organic group having 1 to 10 carbon atoms, or R １ , R ２ and R ３ One of the group consisting of is selected to be an iodine atom or a bromine atom, and the remaining two are combined with each other to form a ring structure with 5 to 20 carbon atoms. However, R １ , R ２ and R ３At least one atom selected from the group consisting of is either an iodine atom or a bromine atom. In formula (w2), X is either an iodine atom or a bromine atom. * represents a bond with another structure in the onium salt compound.

[0239] Suitable onium salt compounds include monomeric compounds and onium salt compounds (onium salt compounds (1) and (2)) that give structural units (II) and (III) respectively in the above-mentioned radiation-sensitive composition.

[0240] 《Polymer》 The polymer contains a structural unit (I) having an acid-dissociable group and has a substructure (w) represented by the following formula (w1) or (w2). (In formula (w1), R １ , R ２ and R ３ Each of these is independently a hydrogen atom, a halogen atom, a cyano group, a nitro group, or a monovalent organic group having 1 to 10 carbon atoms, or R １ , R ２ and R ３ One of the group consisting of is selected to be an iodine atom or a bromine atom, and the remaining two are combined with each other to form a ring structure with 5 to 20 carbon atoms. However, R １ , R ２ and R ３ At least one atom selected from the group consisting of is either an iodine atom or a bromine atom. In formula (w2), X is either an iodine atom or a bromine atom. * represents a bond with other structures in the polymer.

[0241] As such onium salt compounds, the polymer (base polymer) in the above-mentioned radiation-sensitive composition can be suitably used.

[0242] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. In the following examples, "parts" and "%" refer to mass unless otherwise specified. The measurement methods for each physical property are shown below.

[0243] [Weight-average molecular weight (Mw) and number-average molecular weight (Mn) of polymers] The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of polymers were measured by gel permeation chromatography (GPC) using Tosoh Corporation's GPC columns (two "G2000HXL" columns, one "G3000HXL" column, and one "G4000HXL" column) under the following conditions: Eluent: Tetrahydrofuran (Wako Pure Chemical Industries, Ltd.) Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Column temperature: 40°C Detector: Differential refractometer Standard material: Monodisperse polystyrene

[0244] <Synthesis of Compound (M)> [Example M-15] (Synthesis of Monomer (M-15)) Monomer (M-15) was synthesized according to the reaction scheme below.

[0245]

[0246] 30 mmol of 5-vinyl salicylic acid, 39 mmol of the compound represented by formula (S-1), 39 mmol of 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide (EDC), 6 mmol of 4-dimethylaminopyridine (DMAP), and 50 mL of dichloromethane (DCM) were added to a reaction vessel and stirred for 2 hours. 50 mL of 2 M hydrochloric acid was added to separate the organic layer. The layer was washed twice with 50 mL of saturated sodium bicarbonate aqueous solution, and then once with 50 mL of ultrapure water to obtain the compound represented by formula (pM-15).

[0247] 29.74 mmol of the compound represented by compound (pM-15), 148.7 mmol of potassium carbonate, and 100 mL of acetone were added to a reaction vessel. After stirring for 1 hour, 59.47 mmol of 3-bromo-1-iodopropine was added, and the mixture was heated and stirred at 55°C for 5 hours. After cooling to room temperature, the precipitated solid was filtered, and the filtrate was concentrated. The monomer (M-15) was obtained by purification by silica gel column chromatography.

[0248] [Example M-16] (Synthesis of monomer (M-16)) Monomer (M-16) was synthesized according to the reaction scheme below.

[0249]

[0250] 29.74 mmol of 2-hydroxy-4-vinylbenzaldehyde, 148.7 mmol of potassium carbonate, and 100 mL of acetone were added to a reaction vessel. After stirring for 1 hour, 59.47 mmol of 2,3,3-triiodaryl chloride was added, and the mixture was heated and stirred at 55°C for 5 hours. After cooling to room temperature, the precipitated solid was filtered, and the filtrate was concentrated. The filtrate was purified by silica gel column chromatography to obtain the compound represented by the above formula (pM-16).

[0251] 20 mmol of the compound represented by formula (S-2), 21 mmol of compound (pM-16), 4 mmol of p-toluenesulfonic acid (p-TsOH), and 100 mL of toluene were added to the reaction vessel. A Dean-Stark tube was placed in the reaction vessel, and the mixture was heated and stirred under reflux conditions for 4 hours. 50 mL of saturated sodium bicarbonate aqueous solution was added to separate the organic layer. The organic layer was dried over sodium sulfate, and the solvent was removed. The monomer (M-16) was obtained by purification by silica gel chromatography.

[0252] [Example M-19] (Synthesis of monomer (M-19)) Monomer (M-19) was synthesized according to the reaction scheme below.

[0253]

[0254] 20 mmol of 5-bromo-4-hydroxysalicylic acid, 22 mmol of vinylboronic acid, 0.2 mmol of palladium acetate, 60 mmol of sodium carbonate, and 80 mL of ultrapure water were added to a reaction vessel and stirred at room temperature for 1 hour. 320 mL of ultrapure water was added and the mixture was filtered, and the filtrate was neutralized with 2 M hydrochloric acid. After filtering and drying the precipitated solid, it was dissolved in 300 mL of acetone and filtered again. 500 mL of ultrapure water was added to the filtrate and recrystallized to obtain the compound represented by the above formula (ppM-19).

[0255] 29.74 mmol of compound (ppM-19), 148.7 mmol of potassium carbonate, and 100 mL of acetone were added to a reaction vessel. After stirring for 1 hour, 59.47 mmol of 3-bromo-1-iodopropine was added, and the mixture was heated and stirred at 55°C for 5 hours. After cooling to room temperature, the precipitated solid was filtered, and the filtrate was concentrated. The filtrate was purified by silica gel column chromatography to obtain the compound represented by the above formula (pM-19).

[0256] 10 mmol of compound (pM-19), 20 mmol of sodium hydrogen carbonate, 125 mL of dichloromethane, 125 mL of ultrapure water, and 11 mmol of tris(4-fluorophenyl)sulfonium bromide were added to a reaction vessel, and the mixture was stirred at room temperature for 1 hour. After separating the organic layer, it was washed with 100 mL of ultrapure water to obtain monomer (M-19).

[0257] [Example M-20] (Synthesis of monomer (M-20)) Monomer (M-20) was synthesized according to the following reaction scheme.

[0258]

[0259] 20 mmol of zinc, 0.1 mmol of 1,2-dibromoethane, 20 mL of tetrahydrofuran, 1.6 mmol of trimethylsilyl chloride (TMSCl), and 20 mmol of methyl bromodifluoroacetate were added to a reaction vessel, and the mixture was stirred at room temperature for 3 hours. 10 mmol of 1-(4-vinylphenyl)ethanone was added, and the mixture was stirred at room temperature for 6 hours. 100 mL of ethyl acetate and 100 mL of saturated aqueous ammonium chloride solution were added, and the organic layer was separated. It was purified by silica gel column chromatography to obtain the compound represented by the above formula (pppM-20).

[0260] 5 mmol of compound (pppM-20) and 25 mmol of potassium carbonate were added to a reaction vessel. After stirring for 1 hour, 10 mmol of 2,3,3-triiodoallyl chloride was added, and the mixture was heated and stirred at 55 °C for 5 hours. After cooling to room temperature, the precipitated solid was filtered, and the filtrate was concentrated. It was purified by silica gel column chromatography to obtain the compound represented by the above formula (ppM-20).

[0261] 15 mmol of compound (ppM-20), 75 mmol of lithium hydroxide, 10 mL of tetrahydrofuran, and 20 mL of ultrapure water were added to a reaction vessel and stirred at room temperature. 50 mL of dichloromethane was added, and it was washed once with 2M hydrochloric acid and twice with ultrapure water, and the organic layer was separated. Then, it was concentrated to obtain the compound represented by the above formula (pM-20).

[0262] 10 mmol of compound (pM-20), 20 mmol of sodium hydrogen carbonate, 125 mL of dichloromethane, 125 mL of ultrapure water, and 11 mmol of bis(4-trifluoromethylphenyl)-phenylsulfonium chloride were added to a reaction vessel and stirred at room temperature for 1 hour. After separating the organic layer, it was washed with 100 mL of ultrapure water to obtain monomer (M-20).

[0263] <Synthesis of onium salt compound (B)> [Example B-1] (Synthesis of onium salt compound (1) (B-1) as a radiation-sensitive acid generator) According to the following reaction scheme, onium salt compound (1) (hereinafter also referred to as "radiation-sensitive acid generator") (B-15) was synthesized.

[0264]

[0265] 30 mmol of the compound represented by the above formula (S-3), 39 mmol of 3-iodo-2-propynol, 39 mmol of EDC, 6 mmol of DMAP, and 50 mL of dichloromethane were added to a reaction vessel and stirred for 2 hours. 50 mL of 2M hydrochloric acid was added to separate the organic layer. After washing twice with 50 mL of saturated aqueous sodium hydrogen carbonate solution and once with 50 mL of ultrapure water, radiation-sensitive acid generator (B-1) was obtained.

[0266] [Examples B-2 to B-3] (Synthesis of radiation-sensitive acid generators (B-2) to (B-3)) Radiation-sensitive acid generators (B-2) to (B-3) were synthesized in the same manner as in Example B-1, except that the substrates used were appropriately selected.

[0267]

[0268] [Example B-4] (Synthesis of radiation-sensitive acid generator (B-4)) According to the following reaction scheme, radiation-sensitive acid generator (B-4) was synthesized.

[0269]

[0270] 30 mmol of the compound represented by formula (S-4), 39 mmol of (Z)-3-iodopropenoic acid, 39 mmol of EDC, 6 mmol of DMAP, and 50 mL of dichloromethane were added to a reaction vessel and stirred for 2 hours. 50 mL of 2 M hydrochloric acid was added to separate the organic layer. The layer was washed twice with 50 mL of saturated sodium bicarbonate aqueous solution, and then once with 50 mL of ultrapure water to obtain the radiation-sensitive acid generator (B-4).

[0271] [Examples B-5 to B-6, B-9 to B-10, B-19] (Synthesis of radiation-sensitive acid generators (B-5) to (B-6), (B-9) to (B-10), (B-19)) Radiation-sensitive acid generators (B-5) to (B-6), (B-9) to (B-10), (B-19) were synthesized in the same manner as in Example B-4, except that the substrates used were appropriately selected.

[0272]

[0273] [Example B-7] (Synthesis of radiation-sensitive acid generator (B-7)) A radiation-sensitive acid generator (B-7) was synthesized according to the reaction scheme below.

[0274]

[0275] 20 mmol of the compound represented by formula (S-5), 100 mmol of potassium carbonate, and 100 mL of acetone were added to a reaction vessel. After stirring for 1 hour, 40 mmol of 3-bromo-1-iodopropine was added, and the mixture was heated and stirred at 55°C for 5 hours. After cooling to room temperature, the precipitated solid was filtered, and the filtrate was concentrated. The filtrate was purified by silica gel column chromatography to obtain the compound represented by formula (ppB-7).

[0276] 10 mmol of compound (ppB-7), 125 mL of dichloromethane, 125 mL of ultrapure water, and 11 mmol of the compound represented by formula (S-6) were added to a reaction vessel and stirred at room temperature for 1 hour. After separating the organic layer, it was washed with 100 mL of ultrapure water to obtain the compound represented by formula (pB-7).

[0277] 20 mmol of compound (pB-7), 21 mmol of 3-iodopropioaldehyde, 4 mmol of p-TsOH, and 100 mL of toluene were added to a reaction vessel. A Dean-Stark tube was placed in the reaction vessel, and the mixture was heated and stirred under reflux conditions for 4 hours. 50 mL of saturated sodium bicarbonate aqueous solution was added to separate the organic layer. The organic layer was dried over sodium sulfate, and the solvent was removed. The mixture was purified by silica gel chromatography to obtain the radiation-sensitive acid generator (B-7).

[0278] [Examples B-8, B-11 to B-17] (Synthesis of radiation-sensitive acid generators (B-8), (B-11) to (B-17)) Radiation-sensitive acid generators (B-8), (B-11) to (B-17) were synthesized in the same manner as in Example B-7, except that the substrate to be used was appropriately selected.

[0279]

[0280] [Example B-18] (Synthesis of radiation-sensitive acid generator (B-18)) A radiation-sensitive acid generator (B-18) was synthesized according to the reaction scheme below.

[0281]

[0282] 20 mmol of the compound represented by formula (S-7), 100 mmol of potassium carbonate, and 100 mL of acetone were added to a reaction vessel. After stirring for 1 hour, 40 mmol of 3-bromo-1-iodopropine was added, and the mixture was heated and stirred at 55°C for 5 hours. After cooling to room temperature, the precipitated solid was filtered, and the filtrate was concentrated. The filtrate was purified by silica gel column chromatography to obtain a radiation-sensitive acid generator (B-18).

[0283] <Synthesis of Compound (Z)> [Example Z-1] (Synthesis of Onium Salt Compound (2) (Z-1) as an Acid Diffusion Control Agent) Onium salt compound (2) (hereinafter also referred to as "acid diffusion control agent") (Z-1) was synthesized according to the reaction scheme below.

[0284]

[0285] 10 mmol of the compound represented by the above formula (S-8), 20 mmol of sodium hydrogen carbonate, and 50 mL of ultrapure water were added to a reaction vessel and stirred for 30 minutes. Next, 10 mmol of triphenylsulfonium bromide and 50 mL of dichloromethane were added and stirred vigorously for 3 hours. The organic layer was separated and washed twice with 50 mL of ultrapure water. The organic layer was concentrated to obtain an acid diffusion controller (Z-1).

[0286] [Examples Z-2 to Z-4] (Synthesis of acid diffusion controllers (Z-2) to (Z-4)) Acid diffusion controllers (Z-2) to (Z-4) were synthesized in the same manner as in Example Z-1, except that the substrates used were appropriately selected.

[0287]

[0288] [Example Z-5] (Synthesis of acid diffusion controller (Z-5)) An acid diffusion controller (Z-5) was synthesized according to the following reaction scheme.

[0289]

[0290] 20 mmol of methyl 2,4-dihydroxybenzoate, 100 mmol of potassium carbonate, and 100 mL of acetone were added to a reaction vessel. After stirring for 1 hour, 40 mmol of 3-bromo-1-iodopropene was added, and the mixture was heated and stirred at 55 °C for 5 hours. After cooling to room temperature, the precipitated solid was filtered, and the filtrate was concentrated. The compound represented by the above formula (ppZ-5) was obtained by purification by silica gel column chromatography.

[0291] 15 mmol of the compound (ppZ-5), 75 mmol of lithium hydroxide, 10 mL of tetrahydrofuran, and 20 mL of ultrapure water were added to a reaction vessel and stirred at room temperature. 50 mL of dichloromethane was added, and the mixture was washed once with 2 M hydrochloric acid and twice with ultrapure water, and the organic layer was separated. Then, it was concentrated to obtain the compound represented by the above formula (pZ-5).

[0292] 10 mmol of compound (pZ-5), 20 mmol of sodium bicarbonate, and 50 mL of ultrapure water were added to a reaction vessel and stirred for 30 minutes. Next, 10 mmol of the compound represented by the above formula (S-9) and 50 mL of dichloromethane were added and the mixture was vigorously stirred for 3 hours. The organic layer was separated and washed twice with 50 mL of ultrapure water. The organic layer was concentrated to obtain the acid diffusion control agent (Z-5).

[0293] [Examples Z-6 to Z-8, Z-11 to Z-21] (Synthesis of acid diffusion control agents (Z-6) to (Z-8), (Z-11) to (Z-21)) Acid diffusion control agents (Z-6) to (Z-8), (Z-11) to (Z-21) were synthesized in the same manner as in Example Z-5, except that the substrates used were appropriately selected.

[0294]

[0295]

[0296] [Example Z-10] (Synthesis of Acid Diffusion Control Agent (Z-10)) The acid diffusion control agent (Z-10) was synthesized according to the reaction scheme below.

[0297]

[0298] 15 mmol of 3-iodo-1-phenylpropinol, 15 mmol of ethyl chloroglyoxylate, 30 mmol of triethylamine, and 30 mL of dichloromethane were added to a reaction vessel and stirred at room temperature. The mixture was washed twice with saturated sodium bicarbonate solution, and the organic layer was separated. The mixture was then concentrated to obtain the compound represented by the above formula (ppZ-10).

[0299] 15 mmol of compound (ppZ-10), 75 mmol of lithium hydroxide, 10 mL of tetrahydrofuran, and 20 mL of ultrapure water were added to a reaction vessel and stirred at room temperature. 50 mL of dichloromethane was added, and the mixture was washed once with 2 M hydrochloric acid and twice with ultrapure water to separate the organic layer. The resulting mixture was then concentrated to obtain the compound represented by the above formula (pZ-10).

[0300] 10 mmol of compound (pZ-10), 20 mmol of sodium bicarbonate, and 50 mL of ultrapure water were added to a reaction vessel and stirred for 30 minutes. Next, 10 mmol of the compound represented by the above formula (S-10) and 50 mL of dichloromethane were added and the mixture was vigorously stirred for 3 hours. The organic layer was separated and washed twice with 50 mL of ultrapure water. The organic layer was concentrated to obtain the acid diffusion control agent (Z-10).

[0301] [Example Z-9] (Synthesis of acid diffusion control agent (Z-9)) Acid diffusion control agent (Z-9) was synthesized in the same manner as in Example Z-10, except that the substrate used was appropriately selected.

[0302]

[0303] 2. Synthesis of Base Polymers [Polymer Synthesis Examples 1-22 and Polymer Examples 1-4] Synthesis of base polymers Each monomer was combined in the compositions shown in Table 1 below, and copolymerization was carried out under tetrahydrofuran (THF) solvent. After crystallization in methanol and repeated washing with hexane, the mixture was isolated and dried to obtain base polymers A-1 to A-26 having each monomer in the proportions shown in Table 1.

[0304]

[0305] The monomers used in polymerization are shown below.

[0306]

[0307]

[0308] 4. Preparation and Evaluation of Radiation-Sensitive Compositions The compounds used in the preparation of the radiation-sensitive compositions are shown below.

[0309] <[B] Radiation-sensitive acid generators> B-1 to B-22: Compounds represented by the following formulas (B-1) to (B-22)

[0310]

[0311]

[0312]

[0313] <[Z] Acid Diffusion Control Agents> Z-1 to Z-24: Compounds represented by the following formulas (Z-1) to (Z-24)

[0314]

[0315]

[0316]

[0317] [D] Solvent D-1: Propylene glycol monomethyl ether acetate D-2: Propylene glycol 1-monomethyl ether

[0318] <Preparation of Radiation-Sensitive Composition> [Example 1] [A] 100 parts by mass of polymer (A-1) as a base polymer, [B] 30 parts by mass of radiation-sensitive acid generator (B-1), [Z] compound (Z-22) as an acid diffusion control agent at 50 mol% relative to the radiation-sensitive acid generator (B-1), and [D] 2,000 parts by mass of D-1 and 4,800 parts by mass of D-2 as solvents. The resulting mixture was filtered through a membrane filter with a pore size of 0.20 μm to prepare a radiation-sensitive composition (R-1).

[0319] [Examples 2-60 and Comparative Examples 1-10] Radiation-sensitive compositions (R-2) to (R-60) and (CR-1) to (CR-10) were prepared in the same manner as in Example 1, except that the types and amounts of each component shown in Tables 2-1 to 2-2 below were used. In Examples 56-57 and Comparative Examples 6-7, the amount of the [Z] acid diffusion control agent was added so that it was 50 mol% of the amount of monomers that give structural units (II) contained in 100 parts by mass of the [A] base polymer.

[0320]

[0321]

[0322] <Formation of Resist Pattern> (EUV Exposure, Alkaline Development) Each of the radiation-sensitive compositions prepared above was applied to the surface of a 12-inch silicon wafer on which a 40 nm thick underlayer film (AL412 (manufactured by Brewer Science)) had been formed, using a spin coater (CLEAN TRACK ACT12, manufactured by Tokyo Electron). After soft baking at 130°C for 60 seconds, the wafer was cooled at 23°C for 30 seconds to form a 50 nm thick resist film. Next, this resist film was irradiated with EUV light using an EUV exposure machine (model "NXE3300", manufactured by ASML, NA = 0.33, illumination conditions: Conventional s = 0.89, mask: imecDEFECT32FFR02). Subsequently, PEB was performed on the resist film at 110°C for 60 seconds. Next, a 2.38% by mass aqueous TMAH solution was used to develop the image at 23°C for 30 seconds, forming a positive-type 32 nm line-and-space pattern.

[0323] <Formation of Resist Pattern> (KrF Exposure, Alkaline Development) The radiation-sensitive composition prepared above was applied to the surface of a 12-inch silicon wafer on which a 20 nm thick underlayer film (DUV42 (manufactured by Nissan Chemical)) had been formed, using a spin coater (CLEAN TRACK ACT12, manufactured by Tokyo Electron). Spin coating was performed at 130°C for 60 seconds, followed by cooling at 23°C for 30 seconds to form a 70 nm thick resist film. Next, this resist film was irradiated with KrF light using a KrF exposure machine (model "S210D", manufactured by Nikon, NA = 0.55, illumination conditions: Annular s = 0.8, mask 150 nm LS). PEB was performed on the resist film at 110°C for 60 seconds. Then, development was performed using a 2.38 wt% TMAH aqueous solution at 23°C for 30 seconds to form a positive-type 150 nm line and space pattern.

[0324] <Evaluation> The sensitivity, LWR, Min CD, and storage stability of each radiation-sensitive composition were evaluated by measuring each resist pattern formed as described above according to the method below. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-4100") was used to measure the length of the resist patterns. The evaluation results are shown in Tables 3-1 to 3-2 below.

[0325] [Sensitivity] In the formation of the resist pattern by EUV exposure described above, the exposure amount for forming the 32 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 smaller the sensitivity value, the better, as it allows for the formation of the desired resist pattern with less exposure.

[0326] [LWR] The resist pattern formed by the EUV exposure described above was observed from above using the scanning electron microscope described above. The line width was measured at a total of 50 points at arbitrary locations, and the 3-sigma value was determined from the distribution of these measurements, and this was defined as the LWR (unit: nm). A smaller LWR value indicates less line jaggedness and better quality.

[0327] [Min CD] In the formation of the resist pattern by EUV exposure described above, the line width was measured while decreasing the exposure amount, and the minimum line width at which the line did not break or collapse was defined as Min CD (unit: nm). The smaller the Min CD value, the wider and better the process margin for forming the line.

[0328] [Storage Stability] After preparing the radiation-sensitive composition, it was stored for two weeks at two temperature levels: -15°C and 35°C. Subsequently, in the resist pattern formation by KrF exposure described above, the exposure amount for forming a 150 nm line and space pattern was set as the optimal exposure amount, and the sensitivity at 35°C was compared to that at -15°C. Sensitivity E at -15°C Ｌ And sensitivity E when stored at 35°C Ｈ If the sensitivity difference calculated using the following formula was ±1.0% or less, it was judged as "good," and if it exceeded ±1.0%, it was judged as "poor." Sensitivity difference (%) = {(E Ｌ -E Ｈ ) / E Ｈ} × 100

[0329]

[0330]

[0331] As is clear from the results in Tables 3-1 to 3-2, in all of the example radiation-sensitive compositions, sensitivity, LWR, Min CD, and storage stability were improved in a well-balanced manner compared to the comparative example radiation-sensitive compositions.

[0332] The radiation-sensitive composition, pattern-forming method, onium salt compound, and polymer of the present invention can improve sensitivity, LWR, resolution in the low exposure range, and storage stability compared to conventional methods. Therefore, these can be suitably used for forming fine resist patterns in the lithography process of various electronic devices such as semiconductor devices and liquid crystal devices.

Claims

1. A radiation-sensitive composition containing a polymer having a structural unit (I) with an acid-dissociable group and a solvent, wherein the polymer has a partial structure (w) represented by the following formula (w1) or (w2), or the radiation-sensitive composition contains an onium salt compound, the onium salt compound has a partial structure (w) represented by the following formula (w1) or (w2), and generates an acid that dissociates the acid-dissociable group of the polymer upon exposure, and an onium salt compound (1), and has a partial structure (w) represented by the following formula (w1) or (w2), and does not dissociate the acid-dissociable group of the polymer upon exposure, and an onium salt compound (2) that generates an acid, and contains at least one onium salt compound selected from the group consisting of the onium salt compounds (2). (In formula (w1), R １ , R ２ and R ３ are each independently a hydrogen atom, a halogen atom, a nitro group or a monovalent organic group having 1 to 10 carbon atoms, or one selected from the group consisting of R １ , R ２ and R ３ is an iodine atom or a bromine atom, and the remaining two are combined with each other to form a ring structure having 5 to 20 carbon atoms. However, at least one selected from the group consisting of R １ , R ２ and R ３ is an iodine atom or a bromine atom. In formula (w2), X is an iodine atom or a bromine atom. * is a bond with another structure in the corresponding component.) 2. In the above formula (w1), R １ , R ２ and R ３ The radiation-sensitive composition according to claim 1, wherein at least one selected from the group consisting of is an iodine atom, and in the above formula (w2), X is an iodine atom.

3. The radiation-sensitive composition according to claim 1, wherein the onium salt compound (1) has a tertiary organic acid anion and a tertiary onium cation, and the tertiary organic acid anion has the above-mentioned substructure (w).

4. The radiation-sensitive composition according to claim 3, wherein the third organic acid anion has a sulfonate anion, and an electron-withdrawing group is bonded to the carbon atom at the α or β position of the sulfur atom in the sulfonate anion.

5. The radiation-sensitive composition according to claim 3, wherein the third organic acid anion comprises at least one selected from the group consisting of a cyclic structure, -O-, and -CO-.

6. The radiation-sensitive composition according to claim 3, wherein the third onium cation is a sulfonium cation or an iodonium cation.

7. The radiation-sensitive composition according to claim 1, wherein the onium salt compound (2) has a quaternary organic acid anion and a quaternary onium cation, and the quaternary organic acid anion has the substructure (w).

8. The radiation-sensitive composition according to claim 7, wherein the fourth organic acid anion has a sulfonic acid anion or a carboxylic acid anion (provided that if the fourth organic acid anion has a sulfonic acid anion, no electron-withdrawing group is bonded to either the α- or β-carbon atoms of the sulfur atom in the sulfonic acid anion).

9. The radiation-sensitive composition according to claim 7, wherein the above-mentioned fourth organic acid anion comprises at least one selected from the group consisting of a cyclic structure, -O-, and -CO-.

10. The radiation-sensitive composition according to claim 7, wherein the fourth onium cation is a sulfonium cation or an iodonium cation.

11. The radiation-sensitive composition according to claim 1, wherein the polymer comprises at least one selected from the group consisting of: a structural unit (II) having a first organic acid anion and a first onium cation, which generates an acid that dissociates the acid-dissociable group upon exposure; and a structural unit (III) having a second organic acid anion and a second onium cation, which generates an acid that does not dissociate the acid-dissociable group upon exposure; and at least one selected from the group consisting of the first organic acid anion and the second organic acid anion having the substructure (w).

12. The radiation-sensitive composition according to claim 11, wherein the first organic acid anion has a sulfonate anion, an electron-withdrawing group is bonded to the carbon atom at the α or β position of the sulfur atom in the sulfonate anion, and the polymer has the first organic acid anion as a side chain portion.

13. The radiation-sensitive composition according to claim 11, wherein the first onium cation is a sulfonium cation or an iodonium cation.

14. The radiation-sensitive composition according to claim 11, wherein the second organic acid anion has a sulfonic acid anion or a carboxylic acid anion (provided that if the second organic acid anion has a sulfonic acid anion, no electron-withdrawing group is bonded to either the α- or β-carbon atoms of the sulfur atom in the sulfonic acid anion), and the polymer has the second organic acid anion as a side chain portion.

15. The radiation-sensitive composition according to claim 11, wherein the second onium cation is a sulfonium cation or an iodonium cation.

16. The radiation-sensitive composition according to claim 1, wherein the content of structural unit (I) in the total structural units constituting the polymer is 10 mol% or more and 80 mol% or less.

17. The radiation-sensitive composition according to claim 11, wherein the content of structural unit (II) in the total structural units constituting the polymer is 1 mol% or more and 30 mol% or less.

18. The radiation-sensitive composition according to claim 11, wherein the content of structural unit (III) in the total structural units constituting the polymer is 1 mol% or more and 30 mol% or less.

19. The radiation-sensitive composition according to any one of claims 1 to 18, wherein the polymer further comprises a structural unit (IV) having a phenolic hydroxyl group.

20. The radiation-sensitive composition according to any one of claims 1 to 18, further comprising a high-fluorine-content polymer having a higher mass content of fluorine atoms than the polymer.

21. A pattern forming method comprising the steps of: applying a radiation-sensitive composition according to any one of claims 1 to 18 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.

22. The pattern forming method according to claim 21, wherein the exposure is performed using extreme ultraviolet light or an electron beam.

23. An onium salt compound having an organic acid anion and an onium cation, generating acid upon exposure, and having a substructure (w) represented by the following formula (w1) or (w2). (In formula (w1), R １ , R ２ and R ３ Each of these is independently a hydrogen atom, a halogen atom, a cyano group, a nitro group, or a monovalent organic group having 1 to 10 carbon atoms, or R １ , R ２ and R ３ One of the group consisting of is an iodine atom or a bromine atom, and the remaining two are combined to form a ring structure with 5 to 20 carbon atoms. However, R １ , R ２ and R ３ At least one atom selected from the group consisting of is either an iodine atom or a bromine atom. In formula (w2), X is either an iodine atom or a bromine atom. * represents a bond with another structure in the onium salt compound.

24. The onium salt compound according to claim 23, wherein the above organic acid anion has a sulfonate anion or a carboxylic acid anion.

25. A polymer comprising a structural unit (I) having an acid-dissociable group, and having a substructure (w) represented by the following formula (w1) or (w2). (In formula (w1), R １ , R ２ and R ３ Each of these is independently a hydrogen atom, a halogen atom, a cyano group, a nitro group, or a monovalent organic group having 1 to 10 carbon atoms, or R １ , R ２ and R ３ One of the group consisting of is an iodine atom or a bromine atom, and the remaining two are combined to form a ring structure with 5 to 20 carbon atoms. However, R １ , R ２ and R ３ At least one atom selected from the group consisting of is either an iodine atom or a bromine atom. In formula (w2), X is either an iodine atom or a bromine atom. * represents a bond with other structures in the polymer.

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