Radiation-sensitive composition, pattern formation method, and onium salt compound

Abstract

Provided are: a radiation-sensitive composition having excellent sensitivity, CDU, MEEF, development defect suppressing properties, pattern circularity, and pattern rectangularity when forming a pattern; a pattern formation method; and an onium salt compound. This radiation-sensitive composition comprises: an onium salt compound represented by formula (1); a polymer that contains a structural unit having an acid-dissociable group; and a solvent. (In the formula, R1 is a C4-C40 monovalent organic group. A- is –SO3 -, -COO-, or –N--SO2-RX. E1 is -O-, -S-, -SO-, or -SO2-. R2 and R3 are each a hydrogen atom or a C1-C20 monovalent organic group. E is –O- or –NRY-. R4 and R5 are each a C1-C20 monovalent organic group, or R4 and R5 are bonded to represent a C4-C12 ring structure together with a sulfur atom. m is 0 or 1. n is an integer of 0-4.)

Description

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

[0001] The present invention relates to a radiation-sensitive composition, a pattern forming method, and an onium salt compound.

[0002] Photolithography techniques using resist compositions are used to form fine circuits in semiconductor elements. A typical procedure involves, for example, exposing a coating of the resist composition to radiation through a mask pattern to generate an acid, which is then catalyzed by a reaction that causes a difference in the solubility of the polymer in alkaline or organic developers between exposed and unexposed areas, thereby forming a resist pattern on a substrate.

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

[0004] Regarding photoacid generators, which are photosensitive components that are the main components of resist compositions, various structures have been investigated from the viewpoint of cationic structure (see JP-A-2022-68394).

[0005] JP 2022-68394 A

[0006] As patterns become increasingly miniaturized, resist compositions are required to have various resist performances that are equal to or better than conventional ones in terms of sensitivity as well as critical dimension uniformity (CDU), which is an index of the uniformity of line width and hole diameter, mask error enhancement factor (MEEF), which is the amount of change in line width or hole diameter relative to the amount of change in mask size, suppression of development defects, pattern circularity, which indicates the circularity of the hole shape, and pattern rectangularity, which indicates the rectangularity of the cross-sectional shape of the resist pattern.

[0007] An object of the present invention is to provide a radiation-sensitive composition, a pattern forming method, and an onium salt compound that are excellent in sensitivity, CDU, MEEF, development defect suppression, pattern circularity, and pattern rectangularity during pattern formation.

[0008] As a result of extensive research into solving the above problem, the present inventors have found that the above object can be achieved by employing the following configuration, and have thus completed the present invention.

[0009] That is, in one embodiment, the present invention relates to a radiation-sensitive composition comprising: an onium salt compound represented by the following formula (1) (hereinafter also referred to as “onium salt compound (1)”); a polymer including a structural unit having an acid-dissociable group; and a solvent: (In formula (1), R １ is a monovalent organic group having 4 to 40 carbon atoms. - -SO ３ - , -COO - or -N - -SO ２ -R Ｘ It is. Ｘ is a monovalent organic group having 1 to 20 carbon atoms. １ is -O-, -S-, -SO- or -SO ２ - is. R ２ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. E is —O— or —NR Ｙ - is. R Ｙ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. ３ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. ４ and R ５ are each independently a monovalent organic group having 1 to 20 carbon atoms, or R ４ and R ５ R represents a ring structure having 4 to 12 carbon atoms formed by combining with each other and the sulfur atom to which they are attached. ６ R is a halogen atom, a hydroxy group, a nitro group, an amino group, a carboxy group, a cyano group, or a monovalent organic group having 1 to 20 carbon atoms. ６ If there are multiple R６ are the same or different from each other. m is 0 or 1. When m is 1, R ３ -E-CO- and R ２ -E １ - are bonded to the six-membered ring structure to which the sulfur atom in the above formula (1) is bonded. n is an integer of 0 to 4.

[0010] The radiation-sensitive composition contains the onium salt compound (1) as a radiation-sensitive acid generator or acid diffusion controller, and therefore exhibits excellent sensitivity, CDU, MEEF, development defect suppression, pattern circularity, and pattern rectangularity during pattern formation. Without being bound by any theory, the reason for this is presumed to be as follows: Since a substituent having an ester bond or an amide bond is bonded to the aromatic ring of the sulfonium cation of the onium salt compound (1), in addition to a substituent having an ether bond or a sulfur-containing bond, the polarity of the onium salt compound (1) as a whole is enhanced. This allows for control of solubility in a developer, and at the same time, increases compatibility with the base resin, thereby improving dispersibility in a resist film. Furthermore, since the aromatic ring is bonded with a bond capable of extending a conjugated system, such as an ether bond, a sulfur-containing bond, an ester bond, or an amide bond, the light absorption efficiency of the sulfonium cation is improved, thereby increasing the acid generation efficiency from the onium salt compound (1). Furthermore, since the number of carbon atoms in the organic acid anion of the onium salt compound (1) is within a predetermined range, the diffusion length of the generated acid can be appropriately controlled. It is presumed that the combined effects of these factors enable the above-mentioned resist properties to be exhibited.

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

[0012] In the pattern formation method, the radiation-sensitive composition having excellent sensitivity, CDU, MEEF, development defect suppression properties, pattern circularity, and pattern rectangularity is used in pattern formation, and therefore a high-quality resist pattern can be efficiently formed.

[0013] In yet another embodiment, the present invention relates to an onium salt compound represented by the following formula (1a): (In formula (1a), R １ａ is a monovalent organic group having 5 to 40 carbon atoms. - -SO ３ - , -COO - or -N - -SO ２ -R Ｘ It is. Ｘ is a monovalent organic group having 1 to 20 carbon atoms. １ is -O-, -S-, -SO- or -SO ２ - is. R ２ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. E is —O— or —NR Ｙ - is. R Ｙ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. ３ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. ４ and R ５ are each independently a monovalent organic group having 1 to 20 carbon atoms, or R ４ and R ５ represents a ring structure having 4 to 12 carbon atoms that is formed by combining with each other and the sulfur atom to which they are bonded. However, in the ring structure, when the ring containing the sulfur atom in the above formula (1a) and two rings are fused to form a three-ring structure, and the ring containing the sulfur atom in the above formula (1a) contains a heteroatom other than the sulfur atom, the heteroatom is an oxygen atom or a nitrogen atom. ６ R is a halogen atom, a hydroxy group, a nitro group, an amino group, a carboxy group, a cyano group, or a monovalent organic group having 1 to 20 carbon atoms. ６ If there are multiple R ６ are the same or different from each other. m is 0 or 1. When m is 1, R ３ -E-CO- and R ２ -E １ - are bonded to the six-membered ring structure to which the sulfur atom in the above formula (1a) is bonded. n is an integer of 0 to 4.

[0014] The onium salt compound has the developer affinity, acid generation efficiency, and acid diffusion length described above, and is therefore suitable as a radiation-sensitive acid generator or acid diffusion controller for a radiation-sensitive composition.

[0015] In this specification, "organic group" refers to a group containing at least one carbon atom (however, groups that constitute functional groups or characteristic groups by themselves, such as a cyano group or a ketone group, are excluded). "Fused ring structure" refers to a structure in which adjacent rings share one edge (two adjacent atoms). "Bridged ring hydrocarbon group" refers to a polycyclic cyclic hydrocarbon group in which two non-adjacent carbon atoms that constitute the ring are linked by a linking group containing one or more carbon atoms.

[0016] Hereinafter, the embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments. Combinations of preferred aspects are also preferred.

[0017] <Radiation-Sensitive Composition> The radiation-sensitive composition according to this embodiment (hereinafter also referred to simply as the "composition") contains an onium salt compound (1), a polymer containing a structural unit having an acid-dissociable group (hereinafter also referred to as the "base polymer"), and a solvent. The composition may contain other optional components as long as the effects of the present invention are not impaired. By containing the onium salt compound (1) as a radiation-sensitive acid generator or an acid diffusion controller, the radiation-sensitive composition can exhibit excellent sensitivity, CDU, MEEF, development defect suppression, pattern circularity, and pattern rectangularity during pattern formation.

[0018] (Onium Salt Compound (1)) The onium salt compound (1) comprises an organic acid anion represented by the above formula (1) and a sulfonium cation, and functions as a radiation-sensitive acid generator or an acid diffusion controller. The type of function is determined by the organic acid anion. First, the sulfonium cation will be explained, followed by the organic acid anion.

[0019] In the above formula (1), R ２Examples of the monovalent organic group having 1 to 20 carbon atoms and represented by the formula (I) include a monovalent hydrocarbon group having 1 to 20 carbon atoms, a group (a) having a divalent heteroatom-containing group between carbon atoms of the hydrocarbon group (between two adjacent or non-adjacent carbon atoms) or at the end of the hydrocarbon group, a group in which some or all of the hydrogen atoms of the hydrocarbon group or the group (a) have been substituted with a monovalent heteroatom-containing group, or a combination thereof.

[0020] Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, and combinations thereof.

[0021] Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, s-butyl, and t-butyl; alkenyl groups such as ethenyl, propenyl, and butenyl; and alkynyl groups such as ethynyl, propynyl, and butynyl.

[0022] Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include cycloalkyl groups such as a cyclopentyl group and a cyclohexyl group; cycloalkenyl groups such as a cyclopropenyl group, a cyclopentenyl group and a cyclohexenyl group; bridged ring saturated hydrocarbon groups such as a norbornyl group, an adamantyl group and a tricyclodecyl group; and bridged ring unsaturated hydrocarbon groups such as a norbornenyl group and a tricyclodecenyl group.

[0023] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xylyl, naphthyl, and anthryl groups, and aralkyl groups such as benzyl, phenethyl, naphthylmethyl, and anthrylmethyl groups.

[0024] Examples of heteroatoms constituting the divalent or monovalent heteroatom-containing group include oxygen atoms, nitrogen atoms, sulfur atoms, phosphorus atoms, silicon atoms, halogen atoms, etc. Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

[0025] Examples of the divalent heteroatom-containing group include —CO—, —CS—, —NR′—, —O—, —S—, and —SO ２ -, a group formed by combining these, etc. R' is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms.

[0026] Examples of the monovalent heteroatom-containing group include a hydroxy group, a sulfanyl group, a cyano group, a nitro group, and a halogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0027] R ２ As R, a hydrogen atom, an alkyl group, a cycloalkyl group, an acyl group, an alkoxycarbonyl group, an alkoxycarbonylalkyl group, a cycloalkoxycarbonylalkyl group, an alkoxyalkyl group, a lactone structure-containing group (a group in which one hydrogen atom has been removed from a lactone structure), a group in which the hydrogen atom of these groups has been substituted with the above-mentioned monovalent heteroatom-containing group, or a combination thereof is preferred. ２ is preferably a hydrogen atom, a methyl group, an ethyl group, a carboxymethyl group, a t-butoxycarbonylmethyl group, a methylcyclopentyloxycarbonylmethyl group, an ethylcyclopentyloxycarbonylmethyl group, a methyladamantyloxycarbonylmethyl group, an ethyladamantyloxycarbonylmethyl group, an acetyl group, or a pivaloyl group.

[0028] E １ is preferably —O— from the viewpoint of acid generation efficiency.

[0029] R in E Ｙ As the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by R ２ Among the monovalent hydrocarbon groups having 1 to 20 carbon atoms shown in the above, groups having 1 to 10 carbon atoms can be suitably used.

[0030] From the viewpoint of developer affinity, E is preferably —O—.

[0031] R ３ As the monovalent organic group having 1 to 20 carbon atoms represented by R ２ A monovalent organic group having 1 to 20 carbon atoms and represented by the following formula can be suitably used.

[0032] R ３ As R, a hydrogen atom, an alkyl group, a cycloalkyl group, an alkoxycarbonylalkyl group, a cycloalkoxycarbonylalkyl group, a lactone structure-containing group (a group in which one hydrogen atom has been removed from a lactone structure), a benzyl group, a hydroxyalkyl group, a group in which the hydrogen atom of these groups has been substituted with the above-mentioned monovalent heteroatom-containing group, or a combination thereof is preferred. ３ More preferred examples of R are a hydrogen atom, a methyl group, a 2-trifluoroethyl group, a t-butyl group, a t-amyl group, a methylcyclopentyl group, an ethylcyclopentyl group, a carboxymethyl group, a t-butoxycarbonylmethyl group, a methylcyclopentyloxycarbonylmethyl group, an ethylcyclopentyloxycarbonylmethyl group, a methyladamantyloxycarbonylmethyl group, and an ethyladamantyloxycarbonylmethyl group. ３ It is also preferable that the alkyl group contains an acid-dissociable group.

[0033] R ４ and R ５ As the monovalent organic group having 1 to 20 carbon atoms represented by R ２ A monovalent organic group having 1 to 20 carbon atoms and represented by the following formula can be suitably used.

[0034] R ４ and R ５ Examples of the ring structure having 4 to 12 carbon atoms that is formed by combining together with the sulfur atom to which they are bonded include a sulfur atom-containing aliphatic heterocyclic structure having 4 to 12 carbon atoms and a sulfur atom-containing aromatic heterocyclic structure having 4 to 12 carbon atoms. Examples of the sulfur atom-containing aliphatic heterocyclic structure include thietane, tetrahydrothiophene, oxathiolane, thiane, dithiane, thiomorpholine, and thioxane. Examples of the sulfur atom-containing aromatic heterocyclic structure include thiophene, thiazole, benzothiophene, dibenzothiophene, and phenoxathiin. Among these, R ４ and R ５ The ring structure formed by the formula (I) is more preferably tetrahydrothiophene, thioxane, dibenzothiophene, benzothiophene, or phenoxathiin.

[0035] R ４ and R ５ The ring structure may have a substituent. Examples of the substituent include a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom; a hydroxy group; a carboxy group; a cyano group; a nitro group; an alkyl group, an alkoxy group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, or an acyloxy group, or a group in which a hydrogen atom of any of these groups has been substituted with a halogen atom; and an oxo group (═O).

[0036] R ４ and R ５ are preferably each independently a substituted or unsubstituted phenyl group. ４ and R ５ The phenyl group in R ４ and R ５ The ring structure may have a substituent that can be possessed by the ring structure.

[0037] R ６ As the monovalent organic group having 1 to 20 carbon atoms represented by R ２ A monovalent organic group having 1 to 20 carbon atoms and represented by the following formula can be suitably used.

[0038] R ６ As the alkyl group, a hydroxy group, an alkyl group, or a halogen atom is preferred, and a hydroxy group, a methyl group, a fluoro group, an iodo group, a trifluoromethyl group, or a t-butyl group is more preferred.

[0039] Preferably, m is 0.

[0040] n is preferably an integer of 0 to 3, more preferably an integer of 0 to 2, and even more preferably 0 or 1.

[0041] In the above formula (1), R ２ -E １ -R ３ -E-CO- is in an ortho position (R ２ -E １ - and the carbon atom to which R ３It is preferable that the carbon atom to which -E-CO- is bonded is adjacent to the carbon atom to which -E-CO- is bonded. This makes it possible to appropriately control the acid generation efficiency, and the above-mentioned resist performances can be exhibited at a higher level.

[0042] Specific examples of the sulfonium cation of the onium salt compound (1) include, but are not limited to, structures represented by the following formulae (a-1) to (a-104).

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056] As described above, the onium salt compound (1) functions as either a radiation-sensitive acid generator or an acid diffusion controller depending on the structure of the organic acid anion. The radiation-sensitive acid generator is a compound that generates an acid that dissociates the acid-dissociable group upon exposure. The acid diffusion controller is a compound that generates an acid that does not dissociate the acid-dissociable group upon exposure, and has the function of suppressing the diffusion of the acid generated from the radiation-sensitive acid generator in unexposed areas. The acid generated from the acid diffusion controller can be said to be a relatively weaker acid (having a higher pKa) than the acid generated from the radiation-sensitive acid generator. Whether the onium salt compound (1) functions as a radiation-sensitive acid generator or an acid diffusion controller depends on the energy required to dissociate the acid-dissociable group in the base polymer and the acidity of the acid generated upon exposure. The onium salt compound (1) may be contained in the radiation-sensitive composition in a form in which it exists as a sole compound (free from the polymer), in a form incorporated as part of the polymer, or in both forms, although a form in which it exists as a sole compound is preferred.

[0057] Acids that are generated upon exposure include those that generate sulfonic acid, sulfonimide, carboxylic acid, and sulfonamide. The organic acid anion can have a structure corresponding to these.

[0058] Examples of such acids include: (1) compounds in which one or more fluorine atoms, fluorinated hydrocarbon groups, or cyano groups are substituted on the carbon atom at the α- or β-position of the sulfur atom of a sulfo group, (2) compounds having a sulfonimide structure containing a fluorine atom, and (3) compounds in which the carbon atom at the α- or β-position of the sulfur atom of a sulfo group is not substituted with a fluorine atom, a fluorinated hydrocarbon group, or a cyano group. Examples of carboxylic acids generated by exposure include: (4) compounds in which one or more fluorine atoms or fluorinated hydrocarbon groups are substituted on the carbon atom adjacent to a carboxy group, (5) compounds in which the carbon atom adjacent to a carboxy group is not substituted with a fluorine atom or a fluorinated hydrocarbon group, and (6) compounds having a sulfonamide structure which may have a fluorine atom.

[0059] Of these, preferred radiation-sensitive acid generators are those falling under the above categories (1) and (2). Preferred acid diffusion controllers are those falling under the above categories (3) to (6), with those falling under category (3) or (5) being particularly preferred. Even if the structure falls under category (3), it can function as a radiation-sensitive acid generator if an electron-withdrawing group (such as a cyano group) is bonded to the carbon atom at the α- or β-position of the sulfur atom of the sulfo group.

[0060] When the onium salt compound (1) is a radiation-sensitive acid generator, the organic acid anion of the onium salt compound (1) is preferably represented by the following formula (za). (In formula (z-a), R ｚａ is a monovalent organic group having 4 to 40 carbon atoms. ３ - A fluorine atom, a monovalent fluorinated hydrocarbon group, or a cyano group is bonded to the carbon atom at the α- or β-position of

[0061] R ｚａ The monovalent organic group having 4 to 40 carbon atoms represented by the formula (1) is R ２ A group in which the monovalent organic group having 1 to 20 carbon atoms represented by the following formula (I) is extended to have 4 to 40 carbon atoms can be suitably used.

[0062] R ｚａ is preferably a monovalent organic group having 4 to 40 carbon atoms and containing a cyclic structure. The organic group is not particularly limited and may be either a group containing only a cyclic structure or a group combining a cyclic structure and a chain structure. The cyclic structure may be a monocyclic ring, a polycyclic ring, or a combination thereof. The cyclic structure may be an alicyclic structure, an aromatic ring structure, or a combination thereof. In the case of a combination, the cyclic structures may be linked in a chain structure, or two or more cyclic structures may form a fused ring structure. These structures are preferably included as the smallest basic skeleton of the cyclic structure. The number of cyclic structures as the basic skeleton in the organic group may be one or two or more. The divalent heteroatom-containing group may be present between the carbon atoms forming the skeleton of the cyclic structure or the chain structure or at the terminal of the carbon chain, and hydrogen atoms on the carbon atoms of the cyclic structure or the chain structure may be substituted with other substituents.

[0063] The alicyclic structure may be R ２ A structure corresponding to the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms in the above formula can be suitably employed.

[0064] The aromatic ring structure includes R ２ Preferably, a structure corresponding to the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms in the formula (I) can be employed. In addition, aromatic heterocycles such as a furan ring, a pyrrole ring, a thiophene ring, a phosphole ring, a pyrazole ring, an oxazole ring, an isoxazole ring, a thiazole ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a pyridazine ring, and a triazine ring are also preferred.

[0065] The chain structure may be R ２ A structure corresponding to the monovalent chain hydrocarbon group having 1 to 20 carbon atoms in the above formula can be suitably employed.

[0066] The alicyclic structure may also be an aliphatic heterocyclic structure. Examples of the aliphatic heterocyclic structure include oxygen atom-containing aliphatic heterocyclic structures such as oxirane, tetrahydrofuran, tetrahydropyrane, dioxolane, and dioxane; nitrogen atom-containing aliphatic heterocyclic structures such as aziridine, pyrrolidine, piperidine, and piperazine; sulfur atom-containing aliphatic heterocyclic structures such as thietane, thiolane, and thiane; and aliphatic heterocyclic structures containing multiple heteroatoms such as morpholine, 1,2-oxathiolane, and 1,3-oxathiolane.

[0067] The aliphatic heterocyclic structure includes a lactone structure, a cyclic carbonate structure, a sultone structure, a cyclic acetal structure, a cyclic imide structure, or a combination thereof.

[0068] R ｚａ Preferably, contains the above alicyclic structure.

[0069] Examples of the substituents that substitute hydrogen atoms on the carbon atoms of the cyclic structure or chain structure include R ４ and R ５ Substituents that can be possessed by the above ring structure constituted by the following formula can be suitably employed.

[0070] Examples of the monovalent fluorinated hydrocarbon group include a monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms and a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0071] Examples of the monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms include fluorinated alkyl groups such as trifluoromethyl, difluoromethyl, 2,2,2-trifluoroethyl, pentafluoroethyl, 2,2,3,3,3-pentafluoropropyl, 1,1,1,3,3,3-hexafluoropropyl, heptafluoro-n-propyl, heptafluoroisopropyl, nonafluoro-n-butyl, nonafluoroisobutyl, nonafluoro-t-butyl, 2,2,3,3,4,4,5,5-octafluoro-n-pentyl, tridecafluoro-n-hexyl, and 5,5,5-trifluoro-1,1-diethylpentyl; fluorinated alkenyl groups such as trifluoroethenyl and pentafluoropropenyl; and fluorinated alkynyl groups such as fluoroethynyl and trifluoropropynyl.

[0072] Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms include fluorinated cycloalkyl groups such as a fluorocyclopentyl group, a difluorocyclopentyl group, a nonafluorocyclopentyl group, a fluorocyclohexyl group, a difluorocyclohexyl group, an undecafluorocyclohexylmethyl group, a fluoronorbornyl group, a fluoroadamantyl group, a fluorobornyl group, a fluoroisobornyl group, and a fluorotricyclodecyl group; and fluorinated cycloalkenyl groups such as a fluorocyclopentenyl group and a nonafluorocyclohexenyl group.

[0073] The fluorinated hydrocarbon group is preferably a monovalent fluorinated chain hydrocarbon group having 1 to 8 carbon atoms, more preferably a monovalent fluorinated straight chain hydrocarbon group having 1 to 5 carbon atoms.

[0074] Specific examples of the organic acid anion when the onium salt compound (1) is a radiation-sensitive acid generator include, but are not limited to, structures represented by the following formulas (z-1-1) to (z-1-64) (including the structure represented by the above formula (za)).

[0075]

[0076]

[0077]

[0078]

[0079]

[0080]

[0081]

[0082] The onium salt compound (1) as a radiation-sensitive acid generator can be obtained by any combination of the above-mentioned sulfonium cation and the above-mentioned organic acid anion when the onium salt compound (1) is used as a radiation-sensitive acid generator. Specific examples include, but are not limited to, structures represented by the following formulas (1B-1) to (1B-66).

[0083]

[0084]

[0085]

[0086]

[0087]

[0088]

[0089]

[0090]

[0091] The lower limit of the content of the onium salt compound (1) as the radiation-sensitive acid generator (the total content when multiple types are included) is preferably 0.1 parts by mass, more preferably 1 part by mass, even more preferably 2 parts by mass, and particularly preferably 3 parts by mass, relative to 100 parts by mass of the base polymer described below. The upper limit of the content is preferably 100 parts by mass, more preferably 80 parts by mass, even more preferably 60 parts by mass, and particularly preferably 30 parts by mass. This allows the composition to exhibit excellent sensitivity, CDU, MEEF, development defect suppression, pattern circularity, and pattern rectangularity during pattern formation.

[0092] The composition may contain a known radiation-sensitive acid generator other than the onium salt compound (1) as the radiation-sensitive acid generator, as long as the effect of the present invention is not impaired.

[0093] When the onium salt compound (1) is an acid diffusion controller, the organic acid anion of the onium salt compound (1) is preferably represented by the following formula (z-b) or (z-c). (In formulas (z-b) and (z-c), R ｚｂ and R ｚｃ are each independently a monovalent organic group having 4 to 40 carbon atoms. ３ - No fluorine atom, monovalent fluorinated hydrocarbon group, or cyano group is bonded to the carbon atom at the α- or β-position of

[0094] R ｚｂ and R ｚｃ The monovalent organic group having 4 to 40 carbon atoms represented by the formula (za) is R ｚａ A monovalent organic group having 4 to 40 carbon atoms and represented by the following formula can be suitably used.

[0095] R ｚｂ and R ｚｃ R preferably contains at least one structure selected from the group consisting of a cyclic structure, a carbonyl group, and an ether bond. ｚｂ and R ｚｃ As the cyclic structure of the formula (z-a), R ｚａ The cyclic structure shown in the formula (I) can be preferably employed.

[0096] Specific examples of the organic acid anion when the onium salt compound (1) is an acid diffusion controller include, but are not limited to, structures represented by the following formulae (z-2-1) to (z-2-44) (including the structures represented by the above formulae (z-b) and (z-c)).

[0097]

[0098]

[0099]

[0100]

[0101]

[0102] The onium salt compound (1) as an acid diffusion controller can be obtained by arbitrarily combining the above-mentioned sulfonium cation with the above-mentioned organic acid anion when the onium salt compound (1) is used as an acid diffusion controller. Specific examples include, but are not limited to, structures represented by the following formulas (1C-1) to (1C-34).

[0103]

[0104]

[0105]

[0106]

[0107]

[0108] The lower limit of the content of the onium salt compound (1) as the acid diffusion controller (the total content when multiple types are included) is preferably 0.1 parts by mass, more preferably 2 parts by mass, and even more preferably 4 parts by mass, relative to 100 parts by mass of the base polymer described below. The upper limit of the content is preferably 60 parts by mass, more preferably 50 parts by mass, and even more preferably 40 parts by mass. This allows the composition to exhibit excellent sensitivity, CDU, MEEF, development defect suppression, pattern circularity, and pattern rectangularity during pattern formation.

[0109] The composition may contain a known acid diffusion controller other than the onium salt compound (1) as the acid diffusion controller, as long as the effect of the present invention is not impaired.

[0110] (Method for synthesizing onium salt compound (1)) The onium salt compound (1) can be typically synthesized according to the following scheme: ４ and R ５ is an aryl group, m and n are both 0, and R ２ -E １ -R ３ The case where -E-CO- is bonded to the ortho position will be described, but the present invention is not limited to this, and known methods can be used.

[0111] (In the scheme, R １ ~R ３ , E １ , E and A - has the same meaning as in the above formula (1). Ar is an aryl group. - is a trifluorosulfonate anion. ＋ is a monovalent alkali metal. - is a monovalent halide ion. ＋ is a monovalent cation.)

[0112] A diaryl sulfoxide and a benzoic acid derivative are reacted in the presence of a strong acid to form a sulfonium cation. This is then reacted with an alkali metal halide to form a halide salt, which is then reacted with a salt containing the desired organic acid anion for salt exchange, thereby synthesizing the desired onium salt compound (1). Because the cationization in the first step is a Friedel-Crafts type reaction, standard reactants used in such reactions can also be used. Other structures can also be synthesized by appropriately changing the starting materials, intermediate components, etc.

[0113] (Polymer) The polymer (i.e., base polymer) is an aggregate of polymer chains containing a structural unit having an acid-dissociable group (hereinafter also referred to as "structural unit (I)"). The "acid-dissociable group" refers to a group that substitutes a hydrogen atom in a carboxy group, a phenolic hydroxyl group, an alcoholic hydroxyl group, a sulfo group, or the like, and that dissociates under the action of an acid. The radiation-sensitive composition has excellent pattern formability because the polymer contains the structural unit (I).

[0114] In addition to the structural unit (I), the base polymer preferably contains a structural unit (II) containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure, which will be described later, and may contain structural units other than the structural units (I) and (II). Each structural unit will be described below.

[0115] [Structural Unit (I)] The structural unit (I) is a structural unit containing an acid-dissociable group. The structural unit (I) is not particularly limited as long as it has an acid-dissociable group, and examples thereof include a structural unit having a tertiary alkyl ester moiety, a structural unit having a structure in which the hydrogen atom of a phenolic hydroxyl group is substituted with a tertiary alkyl group, and a structural unit having an acetal bond. From the viewpoint of improving the pattern formability of the radiation-sensitive composition, a structural unit represented by the following formula (3) (hereinafter also referred to as "structural unit (I-1)") is preferred.

[0116]

[0117] In the above formula (3), R １７ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. １８ is a monovalent substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms. １９ and R ２０ L each independently represents a monovalent substituted or unsubstituted chain hydrocarbon group having 1 to 10 carbon atoms, a monovalent substituted or unsubstituted alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a divalent alicyclic group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded. １１ teeth, ＊ -COO-, ＊ -L １１ａCOO- or ＊ -COOL １１ａ COO-. １１ａ is a substituted or unsubstituted alkanediyl group or arenediyl group. * is R １７ is the bond to the carbon atom to which it is bonded.

[0118] The above R １７ From the viewpoint of copolymerizability of the monomer that gives the structural unit (I-1), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred.

[0119] L １１ａ Examples of the alkanediyl group represented by the formula (I) include alkanediyl groups having 1 to 10 carbon atoms, such as a methylene group, an ethanediyl group, a 1,3-propanediyl group, and a 2,2-propanediyl group. １１ａ As the alkyl group, a methylene group or an ethanediyl group is preferred.

[0120] L １１ａ Examples of the arenediyl group represented by the formula (I) include divalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, such as benzenediyl and naphthalenediyl groups. １１ａ As the alkyl group, a benzenediyl group is preferred.

[0121] L １１ａ Examples of the substituent that the arenediyl group represented by the formula (I) may have include a halogen atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an alkyl group, a fluorinated alkyl group, an alkoxycarbonyloxy group, an acyl group, an acyloxy group, and an alkoxy group.

[0122] The above R １８ Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a monovalent chain hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0123] The above R １８ ~R ２０ Examples of the monovalent chain hydrocarbon group having 1 to 10 carbon atoms represented by the formula (I) include a monovalent linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, and a monovalent linear or branched unsaturated hydrocarbon group having 1 to 10 carbon atoms.

[0124] The above R １８ ~R ２０ The monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (1) is ２ A monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms in the above formula can be suitably used.

[0125] The above R １８ The monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by the formula (1) is ２ A monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms in the above formula can be suitably used.

[0126] The above R １８ As the alkyl group, a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, or an alicyclic hydrocarbon group having 3 to 20 carbon atoms is preferred.

[0127] The above R １９ and R ２０ The divalent alicyclic group having 3 to 20 carbon atoms constituted by combining these together with the carbon atoms to which they are bonded can suitably be a group in which one hydrogen atom has been removed from the above-mentioned monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0128] Among these, R １８ is an alkyl group, an alkenyl group, or a phenyl group having 1 to 4 carbon atoms, and R １９ and R ２０ The alicyclic structure formed by combining these together with the carbon atoms to which they are bonded is preferably a polycyclic or monocyclic cycloalkane structure.

[0129] The above R １８ ~R ２０ Examples of the substituent that may be possessed by L include １１ａ Substituents that can be possessed by the arenediyl group represented by the following formula can be suitably employed.

[0130] Examples of the structural unit (I-1) include structural units represented by the following formulas (3-1) to (3-14) (hereinafter also referred to as "structural units (I-1-1) to (I-1-14)").

[0131]

[0132]

[0133] In the above formulas (3-1) to (3-14), R １７ ~R ２０ has the same meaning as in formula (3). Ｌ１１ is a halogen atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an alkyl group, a fluorinated alkyl group, an alkoxycarbonyloxy group, an acyl group, an acyloxy group, or an alkoxy group. i and j are each independently an integer of 1 to 4. k and l are each 0 or 1. 3a are each independently an integer of 0 to 3. When 3a is 2 or more, multiple R Ｌ１１ are the same or different from each other. a4 is an integer of 1 to 3.

[0134] i and j are preferably 1. １８ R is preferably a methyl group, an ethyl group, an isopropyl group, a t-butyl group, an ethenyl group, a phenyl group, or an iodophenyl group. １９ and R ２０ R is preferably a methyl group, an ethyl group, or an isopropyl group. Ｌ１１ is preferably an iodine atom, a hydroxy group, or an alkoxy group. Ｌ１１ By employing an iodine atom as the aryl group, an iodine group can be suitably introduced into the structural unit (I).

[0135] Furthermore, the polymer may contain structural units represented by the following formulae (1f) to (2f) as the structural unit (I).

[0136]

[0137] In the above formulas (1f) to (2f), R αｆ R are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. βｆ are each independently a hydrogen atom or a chain alkyl group having 1 to 5 carbon atoms. １ is an integer from 1 to 4.

[0138] The above R βｆ is preferably a hydrogen atom, a methyl group, or an ethyl group. １ As the number, 1 or 2 is preferred.

[0139] The lower limit of the content of the structural unit (I) (the total content when multiple types are contained) relative to all structural units constituting the base polymer is preferably 10 mol%, more preferably 20 mol%, and even more preferably 25 mol%. The upper limit of this content is preferably 80 mol%, more preferably 70 mol%, and even more preferably 65 mol%. By ensuring that the content of the structural unit (I) falls within this range, the pattern formability of the radiation-sensitive composition can be further improved.

[0140] [Structural Unit (II)] The structural unit (II) is a structural unit containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure. By further including the structural unit (II), the base polymer can adjust its solubility in a developer, thereby improving the lithography performance, such as resolution, of the radiation-sensitive composition. Furthermore, the adhesion between a resist pattern formed from the base polymer and a substrate can be improved.

[0141] Examples of the structural unit (II) include structural units represented by the following formulae (T-1) to (T-11).

[0142]

[0143] In the above formula, R Ｌ１ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ｌ２ ~R Ｌ５ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a cyano group, a trifluoromethyl group, a methoxy group, a methoxycarbonyl group, a hydroxy group, a hydroxymethyl group, a dimethylamino group, or a methylcyclopentyloxycarbonyl group. Ｌ４ and R Ｌ５ may be a divalent alicyclic group having 3 to 8 carbon atoms formed by combining together with the carbon atoms to which they are attached. ２ is a single bond or a divalent linking group. X is an oxygen atom or a methylene group. d is an integer of 0 to 3. e is an integer of 1 to 3.

[0144] The above R Ｌ４ and R Ｌ５The divalent alicyclic group having 3 to 8 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded includes R １９ and R ２０ Among divalent alicyclic groups having 3 to 20 carbon atoms constituted by combining these together with the carbon atoms to which they are bonded, groups having 3 to 8 carbon atoms are exemplified. One or more hydrogen atoms on this alicyclic group may be substituted with a hydroxy group.

[0145] The above L ２ Examples of the divalent linking group represented by the formula (I) include a divalent linear or branched hydrocarbon group having 1 to 10 carbon atoms, a divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms, or a group composed of one or more of these hydrocarbon groups and at least one group selected from -CO-, -O-, -NH-, and -S-.

[0146] Of these, the structural unit (II) is preferably a structural unit containing a lactone structure, more preferably a structural unit containing a norbornane lactone structure, and even more preferably a structural unit derived from norbornane lactone-yl (meth)acrylate.

[0147] The lower limit of the content of the structural unit (II) (the total content when multiple types are contained) relative to all structural units constituting the base polymer is preferably 2 mol%, more preferably 5 mol%, and even more preferably 8 mol%. The upper limit of the content is preferably 90 mol%, more preferably 80 mol%, and even more preferably 75 mol%. By setting the content of the structural unit (II) within the above range, the radiation-sensitive composition can further improve lithography performance such as resolution and adhesion of the formed resist pattern to the substrate.

[0148] [Structural Unit (III)] The base polymer optionally has other structural units in addition to the structural units (I) and (II). Examples of the other structural units include a structural unit (III) containing a polar group (excluding those corresponding to the structural units (I) and (II)). By further including the structural unit (III), the base polymer can adjust its solubility in a developer, thereby improving the lithography performance, such as the resolution, of the radiation-sensitive composition. Examples of the polar group include a hydroxy group, a carboxy group, a cyano group, a nitro group, and a sulfonamide group. Among these, a hydroxy group and a carboxy group are preferred, and a hydroxy group is more preferred.

[0149] Examples of the structural unit (III) include structural units represented by the following formula:

[0150]

[0151]

[0152] In the above formula, R Ｋ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0153] When the base polymer has the structural unit (III) having the polar group, the lower limit of the content of the structural unit (III) (the total content when multiple types are contained) relative to all structural units constituting the base polymer is preferably 1 mol%, more preferably 2 mol%, and even more preferably 3 mol%. The upper limit of the content is preferably 30 mol%, more preferably 20 mol%, and even more preferably 15 mol%. By setting the content of the structural unit (III) within the above range, the lithography performance such as resolution of the radiation-sensitive composition can be further improved.

[0154] [Structural Unit (IV)] The base polymer optionally contains, as another structural unit, a structural unit having a phenolic hydroxyl group (hereinafter also referred to as "structural unit (IV)") in addition to the structural unit (III) having the polar group. The structural unit (IV) contributes to improving etching resistance and improving the difference in developer solubility (dissolution contrast) between exposed and unexposed areas. This polymer is suitable for pattern formation using exposure to radiation having a wavelength of 50 nm or less, such as a KrF excimer laser, electron beam, or EUV. In this case, it is preferable that the polymer contains the structural unit (I) in addition to the structural unit (IV).

[0155] The structural unit having a phenolic hydroxyl group is preferably represented by the following formula (4).

[0156] (In the above formula (4), R β is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ＣＡ is a single bond, -COO- ＊ or -O-. * is a bond on the aromatic ring side. R １０２ R is a halogen atom, a cyano group, a nitro group, an alkyl group, an alkoxycarbonyl group, an acyl group, or an acyloxy group. １０２ If there are multiple R １０２ are the same or different. ３ is an integer from 0 to 2, and m ３ is an integer from 1 to 8, and m ４ are each independently an integer of 0 to 8, provided that 1≦m ３ +m ４ ≦2n ３ Meets +5.)

[0157] The above R β From the viewpoint of copolymerizability of the monomer that gives the structural unit (IV), it is preferably a hydrogen atom or a methyl group.

[0158] L ＣＡ is a single bond or -COO- ＊ is preferred.

[0159] R １０２ The halogen atom in is preferably an iodine atom.

[0160] The above n ３ is more preferably 0 or 1, and even more preferably 0.

[0161] The above m ３ is preferably an integer of 1 to 3, more preferably 1 or 2.

[0162] The above m ４ is preferably an integer of 0 to 3, and more preferably an integer of 0 to 2.

[0163] In order to obtain the structural unit (IV), it is preferable to polymerize the corresponding monomer in a state in which the phenolic hydroxyl group is protected with a protecting group such as an alkali-dissociable group (e.g., an acyl group) during polymerization, and then to obtain the structural unit (IV) by deprotecting the phenolic hydroxyl group by hydrolysis. The monomer may also be polymerized without protecting the phenolic hydroxyl group.

[0164] In the case of a polymer for exposure to a KrF excimer laser or radiation having a wavelength of 50 nm or less, the lower limit of the content of the structural unit (IV) (the total content when multiple types are contained) is preferably 20 mol %, more preferably 40 mol %, based on all structural units constituting the base polymer, and the upper limit of the content is preferably 60 mol %, more preferably 50 mol %.

[0165] [Other Structural Units] The base polymer may contain, as a structural unit other than the structural units listed above, a structural unit having an alicyclic structure represented by the following formula (6) (hereinafter also referred to as "structural unit (VII)"). (In the above formula (6), R １α is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ２α is a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0166] In the above formula (6), R ２α The monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (1) is ２ A monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms in the above formula can be suitably used.

[0167] When the base polymer contains the structural unit (VII), the lower limit of the content of the structural unit (VII) is preferably 2 mol%, more preferably 5 mol%, and even more preferably 8 mol%, based on the total structural units constituting the base polymer, and the upper limit of the content is preferably 30 mol%, more preferably 20 mol%, and even more preferably 15 mol%.

[0168] (Method of Synthesizing Base Polymer) The base polymer can be synthesized, for example, by polymerizing monomers that provide each structural unit in an appropriate solvent using a radical polymerization initiator or the like.

[0169] Examples of the radical polymerization initiator include azo radical initiators such as azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and dimethyl 2,2'-azobisisobutyrate; and peroxide radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, and cumene hydroperoxide. Among these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferred, and AIBN is more preferred. These radical initiators can be used alone or in combination of two or more.

[0170] Examples of the solvent used in the polymerization include alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane; cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, and norbornane; aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and cumene; halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, and chlorobenzene; saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, isobutyl acetate, methyl propionate, and propylene glycol monomethyl ether acetate; ketones such as acetone, methyl ethyl ketone, 2-butanone, 4-methyl-2-pentanone, 2-heptanone, and cyclohexanone; ethers such as tetrahydrofuran, dimethoxyethanes, diethoxyethane, and 1,4-dioxanes; Examples of the solvent include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 4-methyl-2-pentanol, and 1-methoxy-2-propanol (propylene glycol monomethyl ether); and lactones such as γ-butyrolactone. These solvents used in the polymerization may be used alone or in combination of two or more.

[0171] The reaction temperature in the polymerization is usually 40° C. to 150° C., preferably 50° C. to 120° C. The reaction time is usually 1 hour to 48 hours, preferably 1 hour to 24 hours.

[0172] The molecular weight of the base polymer is not particularly limited, but the lower limit of the weight average molecular weight (Mw) in terms of polystyrene measured by gel permeation chromatography (GPC) is preferably 3,000, more preferably 4,000, and even more preferably 5,000. The upper limit of Mw is preferably 30,000, more preferably 20,000, and even more preferably 12,000. By setting the Mw of the base polymer within the above range, the resulting resist film can have good heat resistance and developability.

[0173] The ratio (Mw / Mn) of Mw to the polystyrene-equivalent number average molecular weight (Mn) of the base polymer as determined by GPC is usually 1 or more and 5 or less, preferably 1 or more and 3 or less, and more preferably 1 or more and 2 or less.

[0174] The Mw and Mn of the polymer in this specification are values ​​measured using gel permeation chromatography (GPC) under the following conditions.

[0175] GPC columns: 2 G2000HXL, 1 G3000HXL, 1 G4000HXL (all manufactured by Tosoh Corporation) Column temperature: 40°C Elution solvent: tetrahydrofuran Flow rate: 1.0 mL / min Sample concentration: 1.0 mass% Sample injection volume: 100 μL Detector: differential refractometer Standard material: monodisperse polystyrene

[0176] The content of the base polymer is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 55% by mass or more, based on the total solid content of the radiation-sensitive composition.

[0177] (Other Polymers) The radiation-sensitive composition of the present embodiment may contain, as another polymer, a polymer having a higher mass content of fluorine atoms than the base polymer (hereinafter also referred to as a "high-fluorine content polymer"). When the radiation-sensitive composition contains a high-fluorine content polymer, the high-fluorine content polymer can be unevenly distributed in the surface layer of the resist film relative to the base polymer. As a result, it is possible to increase the water repellency of the surface of the resist film during immersion exposure, and to modify the surface of the resist film during EUV exposure and control the distribution of composition within the film.

[0178] The high fluorine content polymer may have, for example, a structural unit represented by the following formula (5) (hereinafter also referred to as "structural unit (V)").

[0179]

[0180] In the above formula (5), R １３ is a hydrogen atom, a methyl group, or a trifluoromethyl group. Ｌ represents a single bond, an alkanediyl group having 1 to 5 carbon atoms, an oxygen atom, a sulfur atom, -COO-, or -SO ２-ONH-, -CONH-, -OCONH- or a combination thereof. １４ is a monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0181] The above R １３ As the alkyl group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (V), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred.

[0182] Above G Ｌ As the group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (V), a single bond and -COO- are preferred, and -COO- is more preferred.

[0183] The above R １４ Examples of the monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a linear or branched alkyl group having 1 to 20 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms.

[0184] The above R １４ Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (I) include monocyclic or polycyclic hydrocarbon groups having 3 to 20 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms.

[0185] The above R １４ As the alkyl group, a fluorinated chain hydrocarbon group is preferable, a fluorinated alkyl group is more preferable, and a 2,2,2-trifluoroethyl group, a 2,2,3,3,3-pentafluoropropyl group, a 1,1,1,3,3,3-hexafluoropropyl group, and a 5,5,5-trifluoro-1,1-diethylpentyl group are even more preferable.

[0186] When the high-fluorine content polymer has the structural unit (V), the lower limit of the content of the structural unit (V) is preferably 50 mol%, more preferably 60 mol%, and even more preferably 70 mol%, based on all structural units constituting the high-fluorine content polymer. The upper limit of the content is preferably 95 mol%, more preferably 90 mol%, and even more preferably 85 mol%. By setting the content of the structural unit (V) within the above range, the mass content of fluorine atoms in the high-fluorine content polymer can be more appropriately adjusted, further promoting uneven distribution of fluorine atoms in the surface layer of the resist film, and as a result, the water repellency of the resist film during immersion exposure can be further improved.

[0187] The high-fluorine content polymer may have a fluorine atom-containing structural unit represented by the following formula (f-2) (hereinafter also referred to as structural unit (VI)) in addition to or instead of the structural unit (V): By having the structural unit (f-2), the high-fluorine content polymer has improved solubility in an alkaline developer, and can suppress the occurrence of development defects.

[0188]

[0189] The structural unit (VI) is roughly classified into two types: (x) a case having an alkali-soluble group, and (y) a case having a group that dissociates under the action of an alkali to increase the solubility in an alkali developer (hereinafter, also simply referred to as an "alkali-dissociable group"). In both (x) and (y), R Ｃ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ｄ is a single bond, a hydrocarbon group having 1 to 20 carbon atoms and a valence of (s+1), and R Ｅ Oxygen atom, sulfur atom, -NR at the end of ｄｄ R has a structure in which -, a carbonyl group, -COO-, -OCO-, or -CONH- is bonded, or a structure in which some of the hydrogen atoms in this hydrocarbon group are substituted with an organic group having a hetero atom. ｄｄ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. s is an integer of 1 to 3.

[0190] When the structural unit (VI) has an alkali-soluble group (x), R Ｆis a hydrogen atom, and A １ is an oxygen atom, -COO-* or -SO ２ O-*. * is R Ｆ The binding site of W is shown. １ represents a single bond, a hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated hydrocarbon group. １ is an oxygen atom, W １ is A １ is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group on the carbon atom to which R is bonded. Ｅ is a single bond or a divalent organic group having 1 to 20 carbon atoms. When s is 2 or 3, multiple R Ｅ , W １ , A １ and R Ｆ may be the same or different. When the structural unit (VI) has an alkali-soluble group (x), it is possible to increase affinity for an alkaline developer and suppress development defects. As the structural unit (VI) having an alkali-soluble group (x), A １ is an oxygen atom and W １ It is particularly preferred that is a 1,1,1,3,3,3-hexafluoro-2,2-methanediyl group.

[0191] When the structural unit (VI) has an alkali-dissociable group (y), R Ｆ is a monovalent organic group having 1 to 30 carbon atoms, and A １ is an oxygen atom, -NR ａａ -, -COO-*, -OCO-* or -SO ２ O-*. R ａａ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. * is R Ｆ The binding site of W is shown. １ is a single bond or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. Ｅ is a single bond or a divalent organic group having 1 to 20 carbon atoms. １ is -COO-*, -OCO-* or -SO ２ If O-*, then W １ or R Ｆ is A １ A has a fluorine atom on the carbon atom bonded to or adjacent to the carbon atom. １is an oxygen atom, W １ , R Ｅ is a single bond, and R Ｄ is a hydrocarbon group having 1 to 20 carbon atoms. Ｅ A carbonyl group is bonded to the end of the R Ｆ is an organic group having a fluorine atom. When s is 2 or 3, a plurality of R Ｅ , W １ , A １ and R Ｆ may be the same or different. When the structural unit (VI) has an alkali-dissociable group (y), the surface of the resist film changes from hydrophobic to hydrophilic in the alkali development step. As a result, affinity to the developer is significantly increased, and development defects can be more efficiently suppressed. Examples of the structural unit (VI) having an alkali-dissociable group (y) include A １ is -COO-*, and R Ｆ Or W １ It is particularly preferred that both of them have a fluorine atom.

[0192] R Ｃ As the alkyl group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (VI), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred.

[0193] When the high-fluorine content polymer has the structural unit (VI), the content of the structural unit (VI) is preferably 30 mol%, more preferably 40 mol%, and even more preferably 50 mol%, based on all structural units constituting the high-fluorine content polymer. The upper limit of the content is preferably 95 mol%, more preferably 90 mol%, and even more preferably 80 mol%. By setting the content of the structural unit (VI) within the above range, it is possible to increase the water repellency of the resist film during immersion exposure and to improve its solubility in an alkaline developer, thereby suppressing the occurrence of development defects.

[0194] [Other Structural Units] The high fluorine content polymer may, if necessary, contain structural units other than the structural units listed above, such as the structural unit (I), the structural unit (III), or the structural unit (VII) in the base polymer.

[0195] When the high-fluorine content polymer contains the structural unit (I), the content of the structural unit (I) is preferably 5 mol %, more preferably 8 mol %, based on all structural units constituting the high-fluorine content polymer, and the upper limit of the content is preferably 40 mol %, more preferably 30 mol %.

[0196] When the high-fluorine content polymer contains the structural unit (III), the content of the structural unit (III) is preferably 5 mol %, more preferably 8 mol %, based on all structural units constituting the high-fluorine content polymer, and the upper limit of the content is preferably 50 mol %, more preferably 40 mol %.

[0197] When the high-fluorine content polymer contains the structural unit (VII), the content of the structural unit (VII) is preferably 20 mol %, more preferably 30 mol %, based on all structural units constituting the high-fluorine content polymer, and the upper limit of the content is preferably 60 mol %, more preferably 50 mol %.

[0198] The lower limit of Mw of the high fluorine content polymer 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 10,000, and even more preferably 8,000.

[0199] The lower limit of Mw / Mn of the high fluorine content polymer is usually 1, more preferably 1.1. The upper limit of Mw / Mn is usually 5, preferably 3, more preferably 2.

[0200] When the radiation-sensitive composition contains a high-fluorine-containing polymer, the lower limit of the content of the high-fluorine-containing polymer is preferably 0.5 parts by mass, more preferably 1 part by mass, and even more preferably 1.5 parts by mass, relative to 100 parts by mass of the base polymer, and the upper limit of the content is preferably 15 parts by mass, more preferably 10 parts by mass, and even more preferably 8 parts by mass.

[0201] By setting the content of the high fluorine content polymer within the above range, the high fluorine content polymer can be more effectively localized in the surface layer of the resist film, which results in improving the water repellency of the surface of the resist film during immersion lithography, and enabling control of the surface modification of the resist film and the distribution of the composition within the film during EUV exposure. The radiation-sensitive composition may contain one or more high fluorine content polymers.

[0202] (Method for synthesizing high fluorine content polymer) The high fluorine content polymer can be synthesized by the same method as the above-mentioned method for synthesizing the base polymer.

[0203] (Solvent) The radiation-sensitive composition according to this embodiment contains a solvent. The solvent is not particularly limited as long as it can dissolve or disperse at least the onium salt compound (1), the base polymer, and optional components that may be contained as desired.

[0204] Examples of the solvent include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

[0205] Examples of alcohol-based solvents include monoalcohol-based 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-based 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-based solvents in which some of the hydroxy groups in the above-mentioned polyhydric alcohol-based solvents are etherified. In this embodiment, alcohol-based solvents also include alcohol acid ester-based solvents, such as methyl lactate, ethyl lactate, propyl lactate, butyl lactate, methyl 2-hydroxyisobutyrate, isopropyl 2-hydroxyisobutyrate, isobutyl 2-hydroxyisobutyrate, and n-butyl 2-hydroxyisobutyrate.

[0206] Examples of ether-based solvents include dialkyl ether-based solvents such as diethyl ether, dipropyl ether, and dibutyl ether; cyclic ether-based solvents such as tetrahydrofuran and tetrahydropyran; aromatic ring-containing ether-based solvents such as diphenyl ether and anisole (methyl phenyl ether); and polyhydric alcohol ether-based solvents obtained by etherifying the hydroxy groups of the above-mentioned polyhydric alcohol-based solvents.

[0207] Examples of the ketone solvent include chain 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.

[0208] Examples of the amide solvent include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; and chain amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0209] Examples of ester-based solvents include monocarboxylic acid ester-based solvents such as n-butyl acetate; polyhydric alcohol partial ether acetate-based solvents such as diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate; lactone-based solvents such as γ-butyrolactone and valerolactone; carbonate-based solvents such as diethyl carbonate, ethylene carbonate, and propylene carbonate; and polyvalent carboxylic acid diester-based solvents such as propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoacetate, and diethyl phthalate.

[0210] 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.

[0211] Among these, alcohol-based solvents, ester-based solvents, and ketone-based solvents are preferred, polyhydric alcohol partial ether acetate-based solvents, polyhydric alcohol partial ether-based solvents, lactone-based solvents, and cyclic ketone-based solvents are more preferred, and propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, γ-butyrolactone, and cyclohexanone are even more preferred. The radiation-sensitive composition may contain one or more solvents.

[0212] (Other Optional Components) The radiation-sensitive composition may contain other optional components in addition to the components described above. Examples of the other optional components include a crosslinking agent, a localization promoter, a surfactant, an alicyclic skeleton-containing compound, and a sensitizer. These other optional components may be used alone or in combination of two or more.

[0213] <Method for Preparing Radiation-Sensitive Composition> The radiation-sensitive composition can be prepared, for example, by mixing the onium salt compound (1), a polymer, and, if necessary, a high-fluorine-content polymer, and a solvent in a predetermined ratio. After mixing, the radiation-sensitive composition is preferably filtered, for example, through a filter having a pore size of about 0.05 μm to 0.40 μm. The solids concentration of the radiation-sensitive composition is usually 0.1% by mass to 50% by mass, preferably 0.5% by mass to 30% by mass, and more preferably 1% by mass to 20% by mass.

[0214] <Pattern Forming Method> A pattern forming method according to one embodiment of the present invention includes: a step (1) of applying the radiation-sensitive composition directly or indirectly to a substrate to form a resist film (hereinafter also referred to as a "resist film forming step"); a step (2) of exposing the resist film (hereinafter also referred to as an "exposure step"); and a step (3) of developing the exposed resist film with a developer (hereinafter also referred to as a "development step").

[0215] According to the pattern formation method, the radiation-sensitive composition is used, which is capable of exhibiting excellent sensitivity, CDU, MEEF, suppression of development defects, pattern circularity, and pattern rectangularity during pattern formation, and therefore a high-quality resist pattern can be efficiently formed. Each step will be described below.

[0216] [Resist Film Forming Step] In this step (step (1) above), a resist film is formed from the radiation-sensitive composition. Examples of substrates on which the resist film is formed include conventionally known substrates such as silicon wafers, silicon dioxide wafers, and aluminum-coated wafers. Alternatively, an organic or inorganic anti-reflective coating, such as those disclosed in JP-B-6-12452 and JP-A-59-93448, may be formed on the substrate. Examples of coating methods include spin coating, casting coating, and roll coating. After coating, if necessary, pre-baking (PB) may be performed to volatilize the solvent in the coating film. The PB temperature is typically 60°C to 160°C, and preferably 80°C to 140°C. The PB time is typically 5 to 600 seconds, and preferably 10 to 300 seconds.

[0217] The lower limit of the thickness of the resist film to be formed is preferably 10 nm, more preferably 15 nm, and even more preferably 20 nm, and the upper limit is preferably 500 nm, more preferably 350 nm, and even more preferably 280 nm.

[0218] When performing immersion exposure, regardless of whether the radiation-sensitive composition contains a water-repellent polymer additive such as a high-fluorine-content polymer, a protective film for immersion exposure that is insoluble in the immersion liquid may be provided on the formed resist film in order to prevent direct contact between the immersion liquid and the resist film. The protective film for immersion exposure may be either a solvent-peelable protective film that is peeled off with a solvent before the development step (see, for example, JP-A No. 2006-227632), or a developer-peelable protective film that is peeled off simultaneously with development in the development step (see, for example, WO 2005-069076 and WO 2006-035790). However, from the viewpoint of throughput, it is preferable to use a developer-peelable protective film for immersion exposure.

[0219] [Exposure Step] In this step (step (2) above), the resist film formed in the resist film formation step (1) above is exposed to radiation through a photomask (or, in some cases, through an immersion liquid such as water). Examples of radiation used for exposure include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV (extreme ultraviolet), X-rays, and gamma rays; and charged particle beams such as electron beams and alpha rays, depending on the line width of the desired pattern. Among these, far ultraviolet light, electron beams, and EUV are preferred, with ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), electron beams, and EUV being more preferred, and electron beams and EUV with wavelengths of 50 nm or less, which are positioned as next-generation exposure technologies, being even more preferred.

[0220] When exposure is performed by immersion exposure, examples of the immersion liquid used include water and fluorine-based inert liquids. The immersion liquid is preferably a liquid that is transparent to the exposure wavelength and has as small a temperature coefficient of refractive index as possible so as to minimize distortion of the optical image projected onto the film. However, particularly when the exposure light source is an ArF excimer laser beam (wavelength 193 nm), water is preferred from the above-mentioned viewpoints, as well as from the viewpoints of ease of availability and ease of handling. When water is used, a small proportion of an additive that reduces the surface tension of water and increases its surfactant power may be added. It is preferable that this additive does not dissolve the resist film on the wafer and has negligible effect on the optical coating on the underside of the lens. Distilled water is preferred as the water used.

[0221] After the exposure, post-exposure baking (PEB) is preferably performed to promote dissociation of acid-dissociable groups in the polymer or the like in the exposed portions of the resist film by the acid generated from the radiation-sensitive acid generator upon exposure. This PEB results in a difference in solubility in a developer between the exposed and unexposed portions. The PEB temperature is typically 50°C to 180°C, preferably 80°C to 130°C. The PEB time is typically 5 seconds to 600 seconds, preferably 10 seconds to 300 seconds.

[0222] [Development Step] In this step (step (3) above), the resist film exposed in the exposure step (step (2) above) is developed. This allows a predetermined resist pattern to be formed. After development, the resist film is generally washed with a rinse liquid such as water or alcohol, and then dried.

[0223] In the case of alkaline development, the developer used in the development may be, for example, an alkaline aqueous solution containing at least one alkaline compound dissolved therein, 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, or 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, an aqueous TMAH solution is preferred, and a 2.38 mass % aqueous TMAH solution is more preferred.

[0224] In the case of organic solvent development, examples of the organic solvent include hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, and alcohol solvents, as well as solvents containing an organic solvent. Examples of the organic solvent include one or more of the solvents listed above as solvents for the radiation-sensitive composition. Among these, ether solvents, ester solvents, and ketone solvents are preferred. As the ether solvent, glycol ether solvents are preferred, and ethylene glycol monomethyl ether and propylene glycol monomethyl ether are more preferred. As the ester solvent, acetate ester solvents are preferred, and n-butyl acetate and amyl acetate are more preferred. As the ketone solvent, chain ketones are preferred, and 2-heptanone is more preferred. The content of the 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 the organic solvent in the developer include water and silicone oil.

[0225] As mentioned above, the developer may be either an alkaline developer or an organic solvent developer, and can be appropriately selected depending on whether the desired pattern is a positive or negative pattern.

[0226] Examples of the developing method include a method of immersing a substrate in a tank filled with a developer for a certain period of time (dip method), a method of developing by piling up a developer on the surface of the substrate by surface tension and leaving it to stand for a certain period of time (puddle method), a method of spraying the developer onto the surface of the substrate (spray method), and a method of continuously discharging the developer while scanning a developer discharging nozzle at a constant speed onto a substrate rotating at a constant speed (dynamic dispense method).

[0227] <Onium Salt Compound> The onium salt compound is represented by the following formula (1a): Such an onium salt compound is a compound in which R of the organic acid anion in the above formula (1) in the radiation-sensitive composition is a １ The onium salt compound (1) can be suitably used, except that the monovalent organic group has 5 to 40 carbon atoms.

[0228] (In formula (1a), R １ａ is a monovalent organic group having 5 to 40 carbon atoms. - -SO ３ - , -COO - or -N - -SO ２ -R Ｘ It is. Ｘ is a monovalent organic group having 1 to 20 carbon atoms. １ is -O-, -S-, -SO- or -SO ２ - is. R ２ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. E is —O— or —NR Ｙ - is. R Ｙ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. ３ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. ４ and R ５are each independently a monovalent organic group having 1 to 20 carbon atoms, or R ４ and R ５ represents a ring structure having 4 to 12 carbon atoms that is formed by combining with each other and the sulfur atom to which they are bonded. However, in the ring structure, when the ring containing the sulfur atom in the above formula (1a) and two rings are fused to form a three-ring structure, and the ring containing the sulfur atom in the above formula (1a) contains a heteroatom other than the sulfur atom, the heteroatom is an oxygen atom or a nitrogen atom. ６ R is a halogen atom, a hydroxy group, a nitro group, an amino group, a carboxy group, a cyano group, or a monovalent organic group having 1 to 20 carbon atoms. ６ If there are multiple R ６ are the same or different from each other. m is 0 or 1. When m is 1, R ３ -E-CO- and R ２ -E １ - are bonded to the six-membered ring structure to which the sulfur atom in the above formula (1a) is bonded. n is an integer of 0 to 4.

[0229] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Measurement methods for various physical properties are shown below.

[0230] [Weight-average molecular weight (Mw) and number-average molecular weight (Mn)] The Mw and Mn of the polymer were measured under the conditions described above. The dispersity (Mw / Mn) was calculated from the measurement results of Mw and Mn.

[0231] [ １３ C-NMR analysis of polymer １３ C-NMR analysis was carried out using a nuclear magnetic resonance spectrometer (JNM-Delta400 manufactured by JEOL Ltd.).

[0232] <Synthesis of Polymer> The monomers used in the synthesis of each polymer in each Example and Comparative Example are shown below. In the following synthesis examples, unless otherwise specified, parts by mass refer to a value when the total mass of the monomers used is taken as 100 parts by mass, and mol % refers to a value when the total number of moles of the monomers used is taken as 100 mol %.

[0233]

[0234]

[0235] Synthesis Example 1 Synthesis of Polymer (A-1) Monomer (M-1), monomer (M-2), monomer (M-5), monomer (M-10), and monomer (M-14) were dissolved in 2-butanone (200 parts by mass) to a molar ratio of 40 / 10 / 20 / 25 / 5 (mol%), and AIBN (azobisisobutyronitrile) (5 mol% relative to 100 mol% of the total monomers used) was added as an initiator to prepare a monomer solution. 2-butanone (100 parts by mass) was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C, and the monomer solution was added dropwise over 3 hours with stirring. The start of the dropwise addition marked the start of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled to below 30°C with water. The cooled polymerization solution was poured into methanol (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with methanol, filtered off, and dried at 50°C for 24 hours to obtain a white powdery polymer (A-1) (yield: 80%). The Mw of the polymer (A-1) was 5,900, and the Mw / Mn was 1.61. １３ As a result of C-NMR analysis, the contents of the structural units derived from (M-1), (M-2), (M-5), (M-10) and (M-14) were 39.3 mol%, 9.4 mol%, 20.5 mol%, 24.8 mol% and 6.0 mol%, respectively.

[0236] Synthesis Examples 2 to 11 (Synthesis of Polymers (A-2) to (A-11)) Polymers (A-2) to (A-11) were synthesized in the same manner as in Synthesis Example 1, except that the types and blending ratios of monomers shown in Table 1 below were used. The content (mol %) of each structural unit and physical properties (Mw and Mw / Mn) of the resulting polymers are also shown in Table 1 below. In Table 1 below, "-" indicates that the corresponding monomer was not used (the same applies to the following tables).

[0237]

[0238] Synthesis Example 12 Synthesis of Polymer (A-12) Monomer (M-1) and monomer (M-29) were dissolved in 1-methoxy-2-propanol (200 parts by mass) to a molar ratio of 55 / 45 (mol %), and MAIB (dimethyl 2,2'-azobisisobutyrate) (4 mol %) was added as an initiator to prepare a monomer solution. 1-Methoxy-2-propanol (100 parts by mass) was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C, and the monomer solution was added dropwise over 3 hours with stirring. The start of the dropwise addition marked the start of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled to below 30°C with water. The cooled polymerization solution was poured into hexane (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane, filtered, and dissolved in 1-methoxy-2-propanol (300 parts by mass). Methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were then added, and a hydrolysis reaction was carried out at 70°C for 6 hours with stirring. After completion of the reaction, the residual solvent was distilled off, and the resulting solid was dissolved in acetone (100 parts by mass) and added dropwise to water (500 parts by mass) to coagulate the polymer. The resulting solid was filtered and dried at 50°C for 13 hours to obtain a white powdery polymer (A-12) (yield: 85%). The Mw of the polymer (A-12) was 7,000, and the Mw / Mn was 1.57. １３ As a result of C-NMR analysis, the content ratios of the structural units derived from (M-1) and (M-29) were 52.3 mol % and 47.8 mol %, respectively.

[0239] [Synthesis Examples 13 to 34] (Synthesis of Polymers (A-13) to (A-34)) Polymers (A-13) to (A-34) were synthesized in the same manner as in Synthesis Example 12, except that the types and blending ratios of monomers shown in Table 2 below were used. Note that the monomer that gives the structural unit (IV) is １３ C-NMR analysis confirmed that the peaks of the carbonyl groups of the acetyl groups had disappeared, and that substantially all of the alkali-dissociable groups had been hydrolyzed to phenolic hydroxyl groups. The content (mol %) of each structural unit and physical properties (Mw and Mw / Mn) of the obtained polymer are also shown in Table 2 below.

[0240]

[0241] Synthesis Example 35 Synthesis of High Fluorine Content Polymer (F-1) Monomer (M-1), monomer (M-15), and monomer (M-20) were dissolved in 2-butanone (200 parts by mass) to give a molar ratio of 20 / 10 / 70 (mol %), and AIBN (5 mol %) was added as an initiator to prepare a monomer solution. 2-Butanone (100 parts by mass) was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C, and the monomer solution was added dropwise over 3 hours with stirring. The start of the dropwise addition marked the start of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled to below 30°C with water. The solvent was replaced with acetonitrile (400 parts by mass), and then hexane (100 parts by mass) was added, stirred, and the acetonitrile layer was collected. This process was repeated three times. The solvent was replaced with propylene glycol monomethyl ether acetate to obtain a solution of high fluorine content polymer (F-1) (yield: 75%). The Mw of the high fluorine content polymer (F-1) was 6,600, and the Mw / Mn was 1.67. １３ As a result of C-NMR analysis, the contents of the structural units derived from (M-1), (M-15) and (M-20) were 19.7 mol %, 10.1 mol % and 70.2 mol %, respectively.

[0242] [Synthesis Examples 36 to 39] (Synthesis of high fluorine content polymer (F-2) to high fluorine content polymer (F-5)) High fluorine content polymer (F-2) to high fluorine content polymer (F-5) were synthesized in the same manner as in Synthesis Example 35, except for using monomers of the types and blending ratios shown in Table 3 below. The content (mol %) of each structural unit and physical properties (Mw and Mw / Mn) of the obtained high fluorine content polymers are also shown in Table 3 below.

[0243]

[0244] <Synthesis of Radiation-Sensitive Acid Generator (B)> [Example B1] (Synthesis of Onium Salt Compound (B-1)) An onium salt compound (B-1) serving as the radiation-sensitive acid generator (B) was synthesized according to the following synthesis scheme.

[0245]

[0246] A reaction vessel was charged with 20.0 mmol of diphenyl sulfoxide, 40.0 mmol of t-butyl-2-methoxybenzoate, and trifluorosulfonic anhydride (Tf ２ 30.0 mmol of HCl and 50 g of dichloromethane were added and stirred at -78°C for 12 hours. Subsequently, saturated aqueous sodium bicarbonate solution was added to the reaction solution to terminate the reaction, followed by extraction with dichloromethane and separation of the organic layer. The resulting organic layer was washed with saturated aqueous sodium chloride solution and then with water. After drying with sodium sulfate, the solvent was distilled off and the mixture was purified by column chromatography to obtain compound (B-1-a) in good yield.

[0247] 50 g of a 1 M aqueous solution of sodium iodide and 50 g of dichloromethane were added to the compound (B-1-a) and stirred at 50° C. for 12 hours. The reaction solution was then extracted with dichloromethane, and the organic layer was separated. The solvent in the resulting organic layer was distilled off, yielding compound (B-1-b) in good yield.

[0248] 20.0 mmol of compound (B-1-c), 50 g of dichloromethane, and 50 g of water were added to the compound (B-1-b) and stirred at room temperature for 4 hours. Dichloromethane was added to the reaction solution for extraction, and the organic layer was separated. The resulting organic layer was washed with a saturated aqueous sodium chloride solution and then with water. After drying with sodium sulfate, the solvent was distilled off, and the mixture was purified by column chromatography to obtain compound (B-1) represented by formula (B-1) in good yield.

[0249] Examples B2 to B37 (Synthesis of onium salt compounds (B-2) to (B-37)) Onium salt compounds represented by the following formulas (B-2) to (B-37) were synthesized as radiation-sensitive acid generators in the same manner as in Example B1, except that the raw materials and precursors were changed as appropriate (onium salt compound (B-1) is also shown).

[0250]

[0251]

[0252]

[0253]

[0254]

[0255] Example C1 Synthesis of Onium Salt Compound (C-1) An onium salt compound (C-1) as an acid diffusion controller (C) was synthesized according to the following synthesis scheme.

[0256]

[0257] A reaction vessel was charged with 20.0 mmol of diphenyl sulfoxide, 40.0 mmol of 2-methoxybenzoic acid, and trifluorosulfonic anhydride (Tf ２ 30.0 mmol of HCl and 50 g of dichloromethane were added and stirred at −78° C. for 12 hours. Water was then added to the reaction solution to terminate the reaction, followed by extraction with dichloromethane and separation of the organic layer. The resulting organic layer was washed with a saturated aqueous sodium chloride solution and then with water. After drying with sodium sulfate, the solvent was distilled off, and the mixture was purified by column chromatography to obtain compound (C-1-a) in good yield.

[0258] 50 g of a 1 M aqueous solution of sodium iodide and 50 g of dichloromethane were added to the compound (C-1-a) and stirred at 50° C. for 12 hours. The reaction solution was then extracted with dichloromethane, and the organic layer was separated. The solvent in the resulting organic layer was distilled off, yielding compound (C-1-b) in good yield.

[0259] 20.0 mmol of compound (C-1-c), 50 g of dichloromethane, and 50 g of water were added to the compound (C-1-b) and stirred at room temperature for 4 hours. Dichloromethane was added to the reaction solution for extraction, and the organic layer was separated. The resulting organic layer was washed with a saturated aqueous sodium chloride solution and then with water. After drying with sodium sulfate, the solvent was distilled off, yielding compound (C-1) represented by formula (C-1) in good yield.

[0260] Examples C2 to C17 Synthesis of onium salt compounds (C-2) to (C-17) Onium salt compounds as acid diffusion controllers represented by the following formulas (C-2) to (C-17) were synthesized in the same manner as in Examples C1 and B1, except that the raw materials and precursors were appropriately changed.

[0261]

[0262]

[0263] The following compounds were used as components other than the components synthesized above.

[0264] [Radiation-sensitive acid generators other than radiation-sensitive acid generators (B-1) to (B-37)] b-1 to b-10: compounds represented by the following formulas (b-1) to (b-10) (hereinafter, the compounds represented by formulas (b-1) to (b-10) may be referred to as "compound (b-1)" to "compound (b-10)", respectively).

[0265]

[0266]

[0267] [Radiation-sensitive acid generators other than acid diffusion controllers (C-1) to (C-17)] cc-1 to cc-6: Compounds represented by the following formulas (cc-1) to (cc-6) (hereinafter, the compounds represented by formulas (cc-1) to (cc-6) may be referred to as "compound (cc-1)" to "compound (cc-6)", respectively).

[0268]

[0269] [Solvent (E)] E-1: Propylene glycol monomethyl ether acetate E-2: Propylene glycol monomethyl ether E-3: γ-butyrolactone E-4: Cyclohexanone

[0270] [Other Additive Components (W)] W-1: MEGAFACE EFS-321 (manufactured by DIC Corporation) (non-fluorine-based) W-2: BYK-399 (manufactured by BYK Japan KK) (non-silicone-based)

[0271] [Preparation of positive-tone radiation-sensitive composition for ArF immersion exposure] [Example 1] 100 parts by mass of (A-1) as the polymer (A), 10.0 parts by mass of (B-1) as the radiation-sensitive acid generator (B), 10.0 parts by mass of (cc-1) as the acid diffusion controller (C), 2.0 parts by mass (solids content) of (F-1) as the high-fluorine-content polymer (F), 0.1 parts by mass of (W-1) as the other additive component (W), and 3,400 parts by mass of a mixed solvent of (E-1) / (E-2) / (E-3) as the solvent (E) were mixed and filtered through a membrane filter having a pore size of 0.2 μm to prepare a radiation-sensitive composition (J-1).

[0272] [Examples 2 to 43, 101 to 103 and Comparative Examples 1 to 13] Radiation-sensitive compositions (J-2) to (J-43), (J-101) to (J-103), and (CJ-1) to (CJ-13) were prepared in the same manner as in Example 1, except that the types and amounts of each component shown in Tables 4-1 and 4-2 below were used.

[0273]

[0274]

[0275] <Formation of Resist Pattern Using Positive Radiation-Sensitive Composition for ArF Immersion Exposure> A composition for forming a bottom antireflective coating ("ARC66" from Brewer Science) was applied to a 12-inch silicon wafer using a spin coater ("CLEAN TRACK ACT12" from Tokyo Electron Limited), and then heated at 205°C for 60 seconds to form a bottom antireflective coating with an average thickness of 100 nm. The positive radiation-sensitive composition for ArF exposure prepared above was applied to this bottom antireflective coating using the spin coater, and prebaked at 100°C for 60 seconds. The wafer was then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 120 nm. Next, this resist film was exposed to light using an ArF excimer laser immersion exposure system (ASML's "TWINSCAN XT-1900i") under optical conditions of NA = 1.35 and dipole (σ = 0.9 / 0.7) through a mask pattern with 50 nm holes and a 100 nm pitch. After exposure, a post-exposure bake (PEB) was performed at 100°C for 60 seconds. Thereafter, the resist film was subjected to alkaline development using a 2.38 mass% aqueous TMAH solution as an alkaline developer, and after development, it was washed with water and further dried to form a positive resist pattern (50 nm holes, 100 nm pitch).

[0276] <Evaluation> The resist patterns formed using the above-mentioned positive radiation-sensitive composition for ArF immersion exposure were evaluated for sensitivity, CDU, MEEF, number of development defects, pattern circularity, and pattern rectangularity according to the methods described below. The results are shown in Tables 5-1 and 5-2 below. The resist patterns were measured using a scanning electron microscope (CG-5000 manufactured by Hitachi High-Technologies Corporation).

[0277] [Sensitivity] In forming a resist pattern using the positive radiation-sensitive composition for ArF immersion exposure, the exposure dose to form a pattern with 50 nm holes and a 100 nm pitch was defined as the optimum exposure dose, and this optimum exposure dose was defined as the sensitivity (mJ / cm ２ The sensitivity was 40 mJ / cm ２ "Good" if below 40 mJ / cm ２ If it exceeded this, it was rated as "poor".

[0278] [CDU] A total of 1,800 resist patterns with 50 nm holes and a 100 nm pitch were measured at arbitrary points from the top of the pattern using the above-mentioned scanning electron microscope. The dimensional variation (3σ) was calculated and used as the CDU (nm). The smaller the CDU value, the smaller the variation in hole diameter over a long period, indicating better results. CDU performance was evaluated as "good" when it was 3.5 nm or less, and "poor" when it exceeded 3.5 nm.

[0279] [MEEF] In the resist patterns resolved by irradiation with the above-mentioned optimum exposure dose, the diameter of the resist pattern formed using a mask pattern with hole diameters of 52 nm, 54 nm, 56 nm, 58 nm, and 60 nm was plotted on the vertical axis against the diameter of the mask pattern on the horizontal axis, and the slope of the line was calculated and defined as MEEF. The closer the MEEF value is to 1, the better the mask reproducibility. MEEF of 2 or less was evaluated as "good," and MEEF of more than 2 was evaluated as "poor."

[0280] [Number of Development Defects] A resist film was exposed to an optimal exposure dose to form a resist pattern with 50 nm holes and a 100 nm pitch, which was used as a wafer for defect inspection. The number of defects on this wafer for defect inspection was measured using a defect inspection device (KLA-Tencor's "KLA2810"). Defects with a diameter of 5 μm or less were determined to be derived from the resist film, and the number was calculated. After development, the number of defects determined to be derived from the resist film was evaluated as "good" if the number of defects was 100 or less, and as "poor" if the number of defects was more than 100.

[0281] [Pattern circularity] The 50 nm holes and 100 nm pitch contact holes formed by irradiating with the optimum exposure dose obtained in the sensitivity evaluation were observed in plan view using the scanning electron microscope described above, and their vertical and horizontal sizes were measured. If the ratio of the vertical size to the horizontal size was 0.90 or more and 1.10 or less, the pattern was evaluated as "A" (good), and if it was less than 0.90 or more than 1.10, the pattern was evaluated as "B" (poor).

[0282] [Pattern Rectangularity] The 50 nm holes and 100 nm pitch contact holes formed by irradiating with the optimum exposure dose obtained in the sensitivity evaluation were observed using the scanning electron microscope described above, and the cross-sectional shape of the contact hole pattern was evaluated. The rectangularity of the resist pattern was evaluated as "A" (very good) if the ratio of the length of the lower side to the length of the upper side (opening diameter) in the cross-sectional shape of the hole portion was 1 or more and 1.05 or less, "B" (good) if it was more than 1.05 and 1.10 or less, and "C" (poor) if it was more than 1.10.

[0283]

[0284]

[0285] As is clear from the results in Tables 5-1 and 5-2, when the radiation-sensitive compositions of the Examples were used in ArF immersion exposure, the sensitivity, CDU, MEEF, development defect performance, and pattern shape were good, whereas the Comparative Examples were inferior in each property to the Examples. Therefore, when the radiation-sensitive compositions of the Examples are used in ArF immersion exposure, resist patterns with high sensitivity and good roughness performance, development defect performance, and pattern shape can be formed.

[0286] [Preparation of Negative Radiation-Sensitive Composition for ArF Immersion Exposure, and Formation and Evaluation of Resist Pattern Using This Composition] [Example 44] 100 parts by mass of (A-8) as the polymer (A), 12.0 parts by mass of (B-2) and 3.0 parts by mass of (B-33) as the radiation-sensitive acid generator (B), 3.0 parts by mass of (cc-6) as the acid diffusion controller (C), 3.0 parts by mass (solids content) of (F-3) as the high fluorine-containing polymer (F), and 3,230 parts by mass of a mixed solvent of (E-1) / (E-2) / (E-3) (mass ratio 2,240 / 960 / 30) as the solvent (E) were mixed, and the mixture was filtered through a membrane filter having a pore size of 0.2 μm, to prepare a radiation-sensitive composition (J-44).

[0287] A composition for forming a bottom antireflective coating ("ARC66" from Brewer Science) was applied to a 12-inch silicon wafer using a spin coater ("CLEAN TRACK ACT12" from Tokyo Electron Limited), and then heated at 205°C for 60 seconds to form a bottom antireflective coating with an average thickness of 100 nm. The negative radiation-sensitive composition for ArF exposure (J-44) prepared above was applied to this bottom antireflective coating using the spin coater, and prebaked at 100°C for 60 seconds. This was followed by cooling at 23°C for 30 seconds to form a resist film with an average thickness of 230 nm. Next, this resist film was exposed to light using an ArF excimer laser immersion exposure system (ASML's "TWINSCAN XT-1900i") under optical conditions of NA = 1.35 and annular (σ = 0.8 / 0.6) through a mask pattern with 80 nm holes and a 150 nm pitch. After exposure, a post-exposure bake (PEB) was performed at 100°C for 60 seconds. The resist film was then developed using n-butyl acetate as an organic solvent developer and dried to form a negative resist pattern (a contact hole pattern with 80 nm holes and a 150 nm pitch).

[0288] The resist patterns formed using the negative-tone radiation-sensitive composition for ArF immersion exposure were evaluated for sensitivity, CDU, MEEF, and pattern circularity in the same manner as in the evaluation of resist patterns formed using the positive-tone radiation-sensitive composition for ArF immersion exposure. As a result, the radiation-sensitive composition of Example 44 exhibited good sensitivity, MEEF, CDU, and pattern circularity, even when a negative-tone resist pattern was formed by ArF immersion exposure.

[0289] [Preparation of Positive-Working Radiation-Sensitive Composition for Extreme Ultraviolet (EUV) Exposure] [Example 45] 100 parts by mass of (A-12) as the polymer (A), 50.0 parts by mass of (B-13) as the radiation-sensitive acid generator (B), 25.0 parts by mass of (C-9) as the acid diffusion controller (C), 5.0 parts by mass (solids content) of (F-5) as the high fluorine-content polymer (F), and 6,800 parts by mass of a mixed solvent of (E-1) / (E-2) as the solvent (E) were mixed and the mixture was filtered through a membrane filter having a pore size of 0.2 μm, to prepare a radiation-sensitive composition (J-45).

[0290] [Examples 46 to 93, 104 to 105 and Comparative Examples 14 to 26] Radiation-sensitive compositions (J-46) to (J-93), (J-104) to (J-105), and (CJ-14) to (CJ-26) were prepared in the same manner as in Example 44, except that the types and amounts of each component shown in Tables 6-1 and 6-2 below were used.

[0291]

[0292]

[0293] <Formation of Resist Pattern Using Positive Radiation-Sensitive Composition for EUV Exposure> A composition for forming a bottom antireflective coating ("ARC66" from Brewer Science) was applied to a 12-inch silicon wafer using a spin coater ("CLEAN TRACK ACT12" from Tokyo Electron Limited), and then heated at 205°C for 60 seconds to form a bottom antireflective coating with an average thickness of 105 nm. The positive radiation-sensitive composition for EUV exposure prepared above was applied to this bottom antireflective coating using the spin coater, and then subjected to PB at 130°C for 60 seconds. Subsequently, the wafer was cooled at 23°C for 30 seconds to form a resist film with an average thickness of 65 nm. Next, this resist film was exposed using an EUV exposure device (ASML's "NXE3300") with NA = 0.33, illumination conditions: Conventional s = 0.89, and mask: imecDEFECT32FFR02. After exposure, PEB was performed at 120°C for 60 seconds. Thereafter, the resist film was subjected to alkaline development using a 2.38 mass% aqueous TMAH solution as an alkaline developer, and after development, the resist film was washed with water and further dried to form a positive resist pattern (30 nm contact hole pattern).

[0294] <Evaluation> The resist patterns formed using the above-described positive-tone radiation-sensitive compositions for EUV exposure were evaluated for sensitivity, CDU, and number of development defects according to the following methods. The results are shown in Tables 7-1 and 7-2 below. The resist patterns were measured using a scanning electron microscope (CG-5000 manufactured by Hitachi High-Technologies Corporation).

[0295] [Sensitivity] In forming a resist pattern using the positive-working radiation-sensitive composition for EUV exposure, the exposure dose required to form a 30 nm contact hole pattern was defined as the optimum exposure dose, and this optimum exposure dose was used as the sensitivity (mJ / cm ２ The sensitivity was 40 mJ / cm ２ The following cases are considered "good" and 40 mJ / cm ２ If it exceeded this, it was rated as "poor".

[0296] [CDU] A resist pattern was formed by adjusting the mask size so that a 30 nm contact hole pattern was formed by irradiating the optimal exposure dose determined in the sensitivity evaluation. The formed resist pattern was observed from above the pattern using the scanning electron microscope described above. The hole diameter was measured at 16 points within a 500 nm range to determine the average value, and this average value was measured at a total of 500 points at any point. The 1 sigma value was calculated from the distribution of the measured values, and this was used as the CDU performance (nm). The smaller the CDU value, the smaller the variation in hole diameter over a long period, and the better the performance. CDU performance was evaluated as "good" when it was 2.0 nm or less, and as "poor" when it exceeded 2.0 nm.

[0297] [Number of Development Defects] A resist film was exposed to an optimum exposure dose to form a 30 nm contact hole pattern, which was used as a wafer for defect inspection. The number of defects on this wafer for defect inspection was measured using a defect inspection device (KLA-Tencor's "KLA2810"). Defects with a diameter of 5 μm or less were determined to be derived from the resist film, and the number was calculated. After development, the number of defects determined to be derived from the resist film was evaluated as "good" when the number of defects was 50 or less, and as "poor" when the number of defects was more than 50.

[0298]

[0299]

[0300] As is clear from the results in Tables 7-1 and 7-2, the radiation-sensitive compositions of the Examples exhibited good sensitivity, CDU, and development defect performance when used for EUV exposure, whereas the Comparative Examples were inferior to the Examples in each of the properties.

[0301] [Preparation of Negative Radiation-Sensitive Composition for EUV Exposure, and Formation and Evaluation of Resist Pattern Using This Composition] [Example 94] 100 parts by mass of (A-15) as the polymer (A), 20.0 parts by mass of (B-10) as the radiation-sensitive acid generator (B), 18.0 parts by mass of (D-4) as the acid diffusion controller (D), 2.0 parts by mass (solids content) of (F-5) as the high fluorine-content polymer (F), and 6,110 parts by mass of a mixed solvent of (E-1) / (E-2) (mass ratio 4,280 / 1,830) as the solvent (E) were mixed, and the mixture was filtered through a membrane filter having a pore size of 0.2 μm, to prepare a radiation-sensitive composition (J-94).

[0302] A composition for forming a bottom antireflective coating ("ARC66" from Brewer Science) was applied to a 12-inch silicon wafer using a spin coater ("CLEAN TRACK ACT12" from Tokyo Electron Limited), and then heated at 205°C for 60 seconds to form a bottom antireflective coating with an average thickness of 105 nm. The negative radiation-sensitive composition for EUV exposure (J-94) prepared above was applied to this bottom antireflective coating using the spin coater, and baked at 130°C for 60 seconds. This was then cooled at 23°C for 30 seconds to form a resist film with an average thickness of 55 nm. Next, this resist film was exposed to light using an EUV exposure system ("NXE3300" from ASML) with NA=0.33, illumination conditions: Conventional s=0.89, and a mask: imecDEFECT32FFR15. After the exposure, PEB was performed for 60 seconds at 120° C. Thereafter, the resist film was developed with n-butyl acetate as an organic solvent developer and dried to form a negative resist pattern (a contact hole pattern with 25 nm holes and a 50 nm pitch).

[0303] The resist pattern formed using the negative-tone radiation-sensitive composition for EUV exposure was evaluated in the same manner as the evaluation of the resist pattern formed using the negative-tone radiation-sensitive composition for ArF immersion exposure. As a result, the radiation-sensitive composition of Example 94 exhibited good sensitivity, CDU, and pattern circularity, even when a negative-tone resist pattern was formed by EUV exposure.

[0304] The radiation-sensitive composition and pattern forming method described above can form a resist pattern that has good sensitivity to exposure light and is excellent in CDU, MEEF, development defect suppression, pattern circularity, and pattern rectangularity. Therefore, these compositions can be suitably used in processing processes for semiconductor devices, which are expected to become even more miniaturized in the future.

Claims

an onium salt compound represented by the following formula (1); a polymer including a structural unit having an acid-dissociable group; Solvent and A radiation-sensitive composition comprising: (In formula (1), R １ is a monovalent organic group having 4 to 40 carbon atoms. A - -SO ３ - , -COO - or -N - -SO ２ -R Ｘ It is. Ｘ is a monovalent organic group having 1 to 20 carbon atoms. E １ is -O-, -S-, -SO- or -SO ２ -It is. R ２ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. E is —O— or —NR Ｙ - is. R Ｙ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ３ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. R ４ and R ５ are each independently a monovalent organic group having 1 to 20 carbon atoms, or R ４ and R ５ represents a ring structure having 4 to 12 carbon atoms that is formed by combining together with the sulfur atom to which they are attached. R ６ R is a halogen atom, a hydroxy group, a nitro group, an amino group, a carboxy group, a cyano group, or a monovalent organic group having 1 to 20 carbon atoms. ６ If there are multiple R ６ are the same or different from each other. m is 0 or 1. When m is 1, R ３ -E-CO- and R ２ -E １ - is bonded to the six-membered ring structure to which the sulfur atom in the above formula (1) is bonded. n is an integer from 0 to 4. 　 In the above formula (1), E and E １ The radiation-sensitive composition according to claim 1 , wherein is —O—. 　 The radiation-sensitive composition according to claim 1 , wherein m is 0. 　 In the above formula (1), R ２ -E １ -R ３ 4. The radiation-sensitive composition according to claim 1, wherein -E-CO- is in an ortho-position relationship. 　 In the above formula (1), R ２ The radiation-sensitive composition according to any one of claims 1 to 3, wherein is an alkyl group, an alkoxyalkyl group, an alkoxycarbonylalkyl group, or a cycloalkoxycarbonylalkyl group. 　 In the above formula (1), R １ The radiation-sensitive composition according to any one of claims 1 to 3, wherein contains at least one structure selected from the group consisting of a cyclic structure, a carbonyl group, and an ether bond. 　 In the above formula (1), A - -SO ３ - and -SO ３ - R for sulfur atom in １ 4. The radiation-sensitive composition according to claim 1, wherein a fluorine atom, a fluorinated hydrocarbon group, or a cyano group is bonded to an α-position carbon or a β-position carbon of the compound. 　 In the above formula (1), A - is -COO - or A - -SO ３ - and -SO ３ - R for sulfur atom in １ 4. The radiation-sensitive composition according to claim 1, wherein no fluorine atom, fluorinated hydrocarbon group, or cyano group is bonded to the α- or β-position carbon of the compound.

4. The radiation-sensitive composition according to claim 1, wherein the content of the onium salt compound is 0.1 parts by mass or more and 100 parts by mass or less based on 100 parts by mass of the polymer.

4. The radiation-sensitive composition according to claim 1, wherein the structural unit having an acid-dissociable group is represented by the following formula (3): (In formula (3), R １７ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R １８ is a monovalent substituted or unsubstituted hydrocarbon group having 1 to 20 carbon atoms. R １９ and R ２０ each independently represents a monovalent substituted or unsubstituted chain hydrocarbon group having 1 to 10 carbon atoms, a monovalent substituted or unsubstituted alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a divalent alicyclic group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded. L １１ teeth, ＊ -COO-, ＊ -L １１ａ COO- or ＊ -COOL １１ａ COO-. １１ａ is a substituted or unsubstituted alkanediyl group or arenediyl group. * indicates R １７ is the bond to the carbon atom to which it is bonded.) 　 a step of directly or indirectly applying the radiation-sensitive composition according to any one of claims 1 to 3 to a substrate to form a resist film; exposing the resist film to light; developing the exposed resist film with a developer; A pattern forming method comprising:

12. The pattern forming method according to claim 11, wherein the exposure is carried out with an ArF excimer laser or extreme ultraviolet light. 　 An onium salt compound represented by the following formula (1a): (In formula (1a), R １ａ is a monovalent organic group having 5 to 40 carbon atoms. A - -SO ３ - , -COO - or -N - -SO ２ -R Ｘ It is. Ｘ is a monovalent organic group having 1 to 20 carbon atoms. E １ is -O-, -S-, -SO- or -SO ２ -It is. R ２ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. E is —O— or —NR Ｙ - is. R Ｙ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ３ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. R ４ and R ５ are each independently a monovalent organic group having 1 to 20 carbon atoms, or R ４ and R ５ represents a ring structure having 4 to 12 carbon atoms that is formed by combining with each other and the sulfur atom to which they are bonded, provided that in the ring structure, when the ring containing the sulfur atom in the above formula (1a) and two other rings are fused to form a tricyclic structure, and when the ring containing the sulfur atom in the above formula (1a) contains a heteroatom other than the sulfur atom, the heteroatom is an oxygen atom or a nitrogen atom. R ６ R is a halogen atom, a hydroxy group, a nitro group, an amino group, a carboxy group, a cyano group, or a monovalent organic group having 1 to 20 carbon atoms. ６ If there are multiple R ６ are the same or different from each other. m is 0 or 1. When m is 1, R ３ -E-CO- and R ２ -E １ - is bonded to the six-membered ring structure to which the sulfur atom in the above formula (1a) is bonded. n is an integer from 0 to 4.

Images