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

Abstract

To provide a radiation-sensitive composition and a pattern forming method capable of exhibiting sensitivity, pattern rectangularity, pattern circularity, exposure margin, focal depth, development defect suppression property, LWR and CDU at sufficient levels when forming a resist pattern, and having good storage stability. A radiation-sensitive composition contains an onium salt compound represented by formula (1), a polymer, and a solvent. In formula (1), Rf is a halogen atom or a cyano group. n is an integer of 0 to 4. When n is 2 or more, multiple Rf groups are the same or different from each other. R1 is a monovalent organic group having 1 to 20 carbon atoms, a hydrogen atom, a halogen atom, a cyano group or a fluorinated alkyl group that binds to a carbon atom to which R1 is bonded via *-COO-, *-OCO-, *-SO2-, *-S-, *-CO-, *-O-CO-O-, *-CONR'- or *-NR'CO-. Each R' independently is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. * is a bond with a carbon atom to which R1 is bonded. Provided that, when n is 0, R1 is a halogen atom or a cyano group. R2 is a hydroxy group, a nitro group, an amino group, a carboxy group, or a monovalent organic group having 1 to 20 carbon atoms. m is an integer of 0 to 4. When m is 2 or more, multiple R2 groups are the same or different from each other. n+m is an integer of 0 to 4. Ar is a monovalent organic group having an aromatic ring having 5 to 40 ring members. X is a methylene group, -O-, -CO- or -SO2-. Provided that when X is a methylene group, the aromatic ring of Ar is directly bonded to S+ in the formula, and R1 does not include a polymerizable group. R41, R42, R43, R44, R45 and R48 are each independently a hydrogen atom, a hydroxy group, a halogen atom or a monovalent organic group having 1 to 20 carbon atoms. R46 and R47 are each independently a hydrogen atom, a hydroxy group, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms, or R46 and R47 are combined to represent a ring structure having 3 to 10 ring members together with two carbon atoms to which they are bonded.

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] In the photolithography technology described above, from the viewpoint of pattern miniaturization, g-line and i-line KrF excimer lasers are being replaced with short-wavelength radiation such as ArF excimer lasers, and liquid immersion lithography, in which exposure is performed in a state in which the space between the lens of the exposure device and the resist film is filled with a liquid medium, is also being used. As a next-generation technology, lithography using shorter-wavelength radiation such as electron beams, X-rays, and EUV (extreme ultraviolet) is also being considered.

[0004] As for the photoacid generator, which is a main component of a resist composition, perfluoroalkylsulfonic acid or a salt thereof capable of imparting strong acidity is often used from the viewpoint of improving sensitivity, resolution, etc. Meanwhile, due to the recent increase in environmental awareness, photoacid generators that do not have a perfluoro structure are being investigated (see Japanese Patent No. 5965855).

[0005] Patent No. 5965855

[0006] In developing a photoacid generator that does not have a perfluoro structure, the resist composition is required to have various performance characteristics that are equivalent to or better than conventional ones in terms of sensitivity, pattern rectangularity, pattern circularity, storage stability, exposure latitude, depth of focus, suppression of development defects, LWR (Line Width Roughness), CDU (Critical Dimension Uniformity), and the like.

[0007] An object of the present invention is to provide a radiation-sensitive composition and a pattern forming method which are capable of exhibiting sufficient levels of sensitivity, pattern rectangularity, pattern circularity, exposure latitude, depth of focus, development defect suppression, LWR, and CDU during resist pattern formation, and which also have good storage stability.

[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 provides 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; and a solvent: (In formula (1), R ｆ is a halogen atom or a cyano group. n is an integer of 0 to 4. When n is 2 or more, multiple R ｆ are the same or different. １ is R １ and the carbon atom to which ＊ -COO-, ＊ -OCO-, ＊ -SO ２ -, ＊ -S-, ＊ -CO-, ＊ —O—CO—O—, ＊ -CONR'- or ＊ A monovalent organic group having 1 to 20 carbon atoms, a hydrogen atom, a halogen atom, a cyano group, or a fluorinated alkyl group bonded via —NR′CO—. Each R′ is independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. ＊ is R １ is a bond to the carbon atom to which it is bonded. However, when n is 0, R １ is a halogen atom or a cyano group. ２ is a hydroxy group, a nitro group, an amino group, a carboxy group, or a monovalent organic group having 1 to 20 carbon atoms. m is an integer of 0 to 4. When m is 2 or more, multiple R ２are the same or different. n+m is an integer of 0 to 4. Ar is a monovalent organic group having an aromatic ring with 5 to 40 ring members. X is a methylene group, —O—, —CO—, or —SO ２ However, when X is a methylene group, the aromatic ring of Ar and S in the formula ＋ and are directly bonded, and R １ does not contain a polymerizable group. ４１ , R ４２ , R ４３ , R ４４ , R ４５ and R ４８ are each independently a hydrogen atom, a hydroxy group, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms. ４６ and R ４７ are each independently a hydrogen atom, a hydroxy group, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms, or R ４６ and R ４７ represents a ring structure having 3 to 10 ring members formed by combining together with the two carbon atoms to which they are attached.

[0010] The radiation-sensitive composition contains the onium salt compound (1) as a radiation-sensitive acid generator, and therefore can exhibit excellent sensitivity, pattern rectangularity, pattern circularity, exposure latitude, depth of focus, development defect suppression, LWR, and CDU during pattern formation, and also has good storage stability. The reason for this is presumed to be as follows, without being bound by any theory.

[0011] In the onium salt compound (1), the halogen atom and electron-withdrawing group bonded to the benzene ring enable the onium salt compound (1) to generate acidity sufficient to change the solubility of the polymer, thereby enabling the compound (1) to exhibit various desired resist properties. Furthermore, the cationic moiety of the onium salt compound (1) has high transparency to radiation due to its structure and high acid generation efficiency, so that acid can be generated efficiently and uniformly throughout the entire thickness direction of the resist film upon exposure, enabling the compound (1) to exhibit various desired resist properties. Furthermore, as a radiation-sensitive acid generator, a compound (1) having an S structure in the cationic moiety is also suitable. ＋and a compound in which the ring structure containing X is a methylene group and the aromatic ring of Ar and S in the formula are ＋ In contrast, in the onium salt compound (1), the S of the cation moiety is not directly bonded to the compound. ＋ The structure containing S becomes a six-membered ring structure. ＋ When X is methylene, the aromatic ring of Ar and S in the formula ＋ and are directly bonded to S ＋ By reducing the cationicity of R, the onium salt compound (1) exhibits a structural stabilizing effect, and its storage stability can be improved. １ In contrast, in the case of the onium salt compound (1), when X is methylene, the reactive polymerizable group is not substituted by R １ Since the resin does not contain a perfluoro structure, its storage stability is not adversely affected. In addition, the absence of a perfluoro structure reduces the environmental impact. It is believed that these combined effects enable the resin to exhibit the desired resist performance and storage stability.

[0012] The term "organic group" refers to a group containing at least one carbon atom, provided that functional or characteristic groups containing a carbon atom (e.g., cyano, carboxy, or carbonyl groups) themselves are not included in the organic group.

[0013] In another embodiment, the present invention relates to a pattern forming method, comprising: a step of applying the radiation-sensitive composition directly or indirectly to a substrate to form a resist film; a step of exposing the resist film; and a step of developing the exposed resist film with a developer.

[0014] The pattern formation method uses the radiation-sensitive composition described above, which exhibits excellent sensitivity, pattern rectangularity, pattern circularity, exposure latitude, depth of focus, development defect suppression, LWR, and CDU during pattern formation, as well as good storage stability, and therefore can efficiently form a high-quality resist pattern.

[0015] In yet another embodiment, the present invention relates to an onium salt compound represented by the following formula (1): (In formula (1), R ｆ is a halogen atom or a cyano group. n is an integer of 0 to 4. When n is 2 or more, multiple R ｆ are the same or different. １ is R １ and the carbon atom to which ＊ -COO-, ＊ -OCO-, ＊ -SO ２ -, ＊ -S-, ＊ -CO-, ＊ —O—CO—O—, ＊ -CONR'- or ＊ A monovalent organic group having 1 to 20 carbon atoms, a hydrogen atom, a halogen atom, a cyano group, or a fluorinated alkyl group bonded via —NR′CO—. Each R′ is independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. ＊ is R １ is a bond to the carbon atom to which it is bonded. However, when n is 0, R １ is a halogen atom or a cyano group. ２ is a hydroxy group, a nitro group, an amino group, a carboxy group, or a monovalent organic group having 1 to 20 carbon atoms. m is an integer of 0 to 4. When m is 2 or more, multiple R ２ are the same or different. n+m is an integer of 0 to 4. Ar is a monovalent organic group having an aromatic ring with 5 to 40 ring members. X is a methylene group, —O—, —CO—, or —SO ２ However, when X is a methylene group, the aromatic ring of Ar and S in the formula ＋ and are directly bonded, and R １ does not contain a polymerizable group. ４１ , R ４２ , R ４３ , R ４４ , R ４５ and R ４８ are each independently a hydrogen atom, a hydroxy group, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms. ４６ and R４７ are each independently a hydrogen atom, a hydroxy group, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms, or R ４６ and R ４７ represents a ring structure having 3 to 10 ring members formed by combining together with the two carbon atoms to which they are attached.

[0016] Since the onium salt compound (1) has a specific structure, when it is blended into a radiation-sensitive composition, the composition can exhibit excellent sensitivity, pattern rectangularity, pattern circularity, exposure latitude, depth of focus, development defect suppression, LWR, and CDU during pattern formation, as well as good storage stability.

[0017] 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 embodiments are also preferred.

[0018] <Radiation-Sensitive Composition> The radiation-sensitive composition according to this embodiment (hereinafter also simply referred to as "composition") contains an onium salt compound (1), a polymer (hereinafter also referred to as "base polymer"), and a solvent. It may further contain an acid diffusion controller as needed. The composition may contain other optional components as long as they do not impair the effects of the present invention.

[0019] (Onium Salt Compound) The onium salt compound (1) is represented by the above formula (1) and functions as a radiation-sensitive acid generator that generates an acid upon irradiation (exposure) with radiation. The acid generated upon exposure dissociates the acid-dissociable group of the structural unit (I) that the base polymer may have, thereby generating a carboxyl group or the like.

[0020] R ｆ The halogen atom includes a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. Among them, R ｆ is preferably a fluorine atom, an iodine atom, or a cyano group.

[0021] n is preferably an integer of 1 to 4, more preferably an integer of 2 to 4, even more preferably 3 or 4, and particularly preferably 4.

[0022] R １The monovalent organic group having 1 to 20 carbon atoms represented by the formula (I) is not particularly limited, and may include a monovalent hydrocarbon group having 1 to 20 carbon atoms, a group in which some or all of the hydrogen atoms contained in the hydrocarbon group have been substituted with substituents (hereinafter also referred to as "group (α)"), and a group in which -CO-, -CS-, -O-, -S-, -SO ２ -, -NR'-, or a group containing a combination of two or more of these (hereinafter also referred to as "group (β)"), or a combination thereof. R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. However, R １ The monovalent organic group having 1 to 20 carbon atoms represented by the formula (I) does not include a fluorinated alkyl group.

[0023] 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.

[0024] Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include a linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms, and a linear or branched unsaturated hydrocarbon group having 1 to 20 carbon atoms.

[0025] Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include monocyclic or polycyclic saturated hydrocarbon groups, and monocyclic or polycyclic unsaturated hydrocarbon groups. Preferred monocyclic saturated hydrocarbon groups include cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. Preferred polycyclic cycloalkyl groups include bridged alicyclic hydrocarbon groups such as norbornyl, adamantyl, tricyclodecyl, and tetracyclododecyl groups. Examples of monocyclic unsaturated hydrocarbon groups include monocyclic cycloalkenyl groups such as cyclopropenyl, cyclobutenyl, cyclopentenyl, and cyclohexenyl groups. Examples of polycyclic unsaturated hydrocarbon groups include polycyclic cycloalkenyl groups such as norbornenyl, tricyclodecenyl, and tetracyclododecenyl groups. A bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two non-adjacent carbon atoms constituting the alicyclic ring are linked by a linking group containing one or more carbon atoms.

[0026] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xylyl, naphthyl, and anthryl; and aralkyl groups such as benzyl, phenethyl, and naphthylmethyl.

[0027] The group (β) is also preferably a group containing a heterocyclic group containing a heteroatom between carbon atoms constituting the ring. Examples of the heterocyclic group include a group in which one hydrogen atom has been removed from an aromatic heterocyclic structure and a group in which one hydrogen atom has been removed from an aliphatic heterocyclic structure. Examples of the heteroatom include an oxygen atom, a nitrogen atom, and a sulfur atom.

[0028] Examples of the aromatic heterocyclic structure include: oxygen atom-containing aromatic heterocyclic structures such as furan, pyran, benzofuran, and benzopyran; nitrogen atom-containing aromatic heterocyclic structures such as pyrrole, imidazole, pyridine, pyrimidine, pyrazine, indole, quinoline, isoquinoline, acridine, phenazine, and carbazole; sulfur atom-containing aromatic heterocyclic structures such as thiophene; and aromatic heterocyclic structures containing multiple heteroatoms such as thiazole, benzothiazole, thiazine, and oxazine.

[0029] Examples of the aliphatic heterocyclic structure include: oxygen atom-containing aliphatic heterocyclic structures such as oxirane, tetrahydrofuran, tetrahydropyran, 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.

[0030] Examples of the aliphatic heterocyclic structure include a lactone structure, a cyclic carbonate structure, a sultone structure, and a structure containing a cyclic acetal, such as those represented by the following formulas (H-1) to (H-11).

[0031]

[0032] In the above formula, γ is an integer of 1 to 3.

[0033] R １ Examples of the substituent in 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, 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).

[0034] R １ The halogen atom represented by the above R ｆ The halogen atoms shown below can be preferably used.

[0035] R １Examples of the fluorinated alkyl group represented by the formula (I) include alkyl groups having 1 to 10 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms. Specific examples include a trifluoromethyl group, a difluoromethyl group, a 2,2,2-trifluoroethyl group, a pentafluoroethyl group, a 2,2,3,3,3-pentafluoropropyl group, a 1,1,1,3,3,3-hexafluoropropyl group, a heptafluoro n-propyl group, a heptafluoro i-propyl group, a nonafluoro n-butyl group, a nonafluoro i-butyl group, a nonafluoro t-butyl group, a 2,2,3,3,4,4,5,5-octafluoro n-pentyl group, a tridecafluoro n-hexyl group, and a 5,5,5-trifluoro-1,1-diethylpentyl group.

[0036] R １ is R １ and the carbon atom to which ＊ -COO-, ＊ -OCO-, ＊ -SO ２ -or ＊ It is preferably a monovalent organic group having 1 to 20 carbon atoms, a halogen atom, or a fluorinated alkyl group bonded via —CO—.

[0037] R １ The monovalent organic group having 1 to 20 carbon atoms represented by the formula (I) is preferably an alkyl group, a cycloalkyl group, an acyl group, a group containing a cyclic acetal structure, a group containing a lactone structure, or a group in which some or all of the hydrogen atoms of these groups have been substituted with a substituent, or a combination thereof. As the cyclic acetal structure or lactone structure, the groups shown in the above-mentioned aliphatic heterocyclic structure can be suitably used. Furthermore, as the substituent, the above-mentioned R １ The substituents in the following formula can be suitably employed.

[0038] R ２ The monovalent organic group having 1 to 20 carbon atoms represented by the above R １ A monovalent organic group having 1 to 20 carbon atoms and represented by the following formula can be suitably used. ２ The monovalent organic group having 1 to 20 carbon atoms represented by the formula (I) is preferably an alkoxy group, an alkoxycarbonyl group, or an alkoxyamide group.

[0039] m is preferably an integer of 0 to 3, more preferably an integer of 0 to 2, and even more preferably 0 or 1.

[0040] Specific examples of the anion moiety of the onium salt compound (1) include, but are not limited to, structures of the following formulae (1-1-1) to (1-1-54).

[0041]

[0042]

[0043]

[0044]

[0045] In the above formula (1), the monovalent organic group having an aromatic ring with 5 to 40 ring members represented by Ar is a monovalent organic group having an aromatic ring with 5 to 40 ring members and the above R １ and a monovalent organic group having 1 to 20 carbon atoms, represented by the following formula: Ar may contain the aromatic ring in the skeleton (between two atoms) that constitutes the monovalent organic group, or may have the aromatic ring at the end of the skeleton that constitutes the monovalent organic group.

[0046] Examples of the aromatic ring having 5 to 40 ring members in Ar include aromatic hydrocarbon rings such as a benzene ring, a naphthalene ring, an anthracene ring, a phenalene ring, a phenanthrene ring, a pyrene ring, a fluorene ring, a perylene ring, and a coronene ring, and 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, and combinations thereof. The aromatic ring of Ar is preferably a benzene ring or a naphthalene ring, and more preferably a benzene ring ... ＋ It is more preferable that it is directly bonded to

[0047] X is a methylene group, —O—, or —SO ２ It is preferably -, more preferably a methylene group or -O-, and most preferably -O-.

[0048] However, when X is a methylene group, the aromatic ring of Ar and S in the formula ＋ and are directly bonded, and R １ The polymerizable group does not contain a polymerizable group. The polymerizable group is an ethylenically unsaturated double bond or a structure containing an ethylenically unsaturated double bond as a partial structure constituting a ring (for example, a norbornene ring, a maleimide ring, etc.).

[0049] R ４１ , R ４２ , R ４３ , R ４４ , R ４５ , R ４６ , R ４７ and R ４８ The halogen atom represented by the above R ｆ The halogen atoms shown below can be preferably used.

[0050] R ４１ , R ４２ , R ４３ , R ４４ , R ４５ , R ４６ , R ４７ and R ４８ The monovalent organic group having 1 to 20 carbon atoms represented by the above R １ A monovalent organic group having 1 to 20 carbon atoms and represented by the following formula can be suitably used.

[0051] R ４６ and R ４７ As a ring structure having 3 to 10 ring members formed by combining these together with the two carbon atoms to which they are bonded, there is S in the above formula (1). ＋ A cycloalkane structure that forms a condensed ring with a 6-membered ring structure containing R ４６ and R ４７ The cycloalkane formed by the above R １ A structure corresponding to the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms in the above formula can be suitably employed.

[0052] R ４１ , R ４２ , R ４３ , R ４４ , R ４５ , R ４６ , R４７ and R ４８ are preferably all hydrogen atoms.

[0053] Specific examples of the cation moiety of the onium salt compound (1) include, but are not limited to, structures of the following formulae (1-2-1) to (1-2-44).

[0054]

[0055]

[0056]

[0057] The onium salt compound (1) can be obtained by appropriately combining the above-mentioned anion moiety and the above-mentioned cation moiety. Specific examples include, but are not limited to, structures of the following formulae (1-1) to (1-61).

[0058]

[0059]

[0060]

[0061]

[0062]

[0063] The lower limit of the content of the onium salt compound (1) (when multiple types of onium salt compounds (1) are contained, the total amount thereof) is preferably 0.1 parts by mass, more preferably 1 part by mass, and even more preferably 2 parts by mass, relative to 100 parts by mass of the polymer described below. The upper limit of the content is preferably 50 parts by mass, more preferably 40 parts by mass, and even more preferably 35 parts by mass. It is particularly preferable that the content be less than 20 parts by mass (less than 20 parts by mass). The content of the onium salt compound (1) is appropriately selected depending on the type of polymer used, exposure conditions, desired sensitivity, and the like. This allows the composition to maintain its storage stability while exhibiting excellent sensitivity, pattern rectangularity, pattern circularity, exposure margin, depth of focus, development defect suppression, LWR, and CDU during resist pattern formation.

[0064] (Method for Synthesizing Onium Salt Compound (1)) The desired onium salt compound (1) can be synthesized by salt exchange between an onium salt containing a diaryliodonium cation and a salt (e.g., a metal salt) of the anion portion of onium salt compound (1), followed by nucleophilic reaction of a thioxane analog with the diaryliodonium cation. Alternatively, the desired onium salt compound (1) can be synthesized by reacting an aryl alkyl ketone with a trimethylsilane halide to produce an enol ether, which is then nucleophilically reacted with a thioxane oxide analog to form a salt having the cation portion of onium salt compound (1), and finally salt exchange with a salt (e.g., a metal salt) of the anion portion of onium salt compound (1). The desired onium salt compound (1) can be synthesized by appropriately modifying the structures of the raw materials and intermediate reactants.

[0065] The radiation-sensitive composition may contain, in addition to the onium salt compound (1), another radiation-sensitive acid generator (for example, the following ionic radiation-sensitive acid generator (P1) or the following non-ionic radiation-sensitive acid generator (P2)).

[0066] <Ionic Radiation-Sensitive Acid Generator (P1)> Examples of the ionic radiation-sensitive acid generator (P1) include onium salt compounds (P1) represented by the following formula (P1) (excluding those corresponding to the onium salt compound (1)): (In formula (P1), R ４０ is a monovalent organic group having 1 to 40 carbon atoms. ｆ２１ and R ｆ２２ are each independently a hydrogen atom, a cyano group, a fluorine atom, or a monovalent fluorinated hydrocarbon group, provided that R bonded to the carbon atom adjacent to the sulfonate anion ｆ２１ and R ｆ２２ At least one of R is a fluorine atom, a monovalent fluorinated hydrocarbon group, or a cyano group. ｆ２１ and R ｆ２２ If there are multiple R ｆ２１ and R ｆ２２ are the same or different, and n is an integer of 1 to 4. Z ２＋ is a radiation-sensitive onium cation.

[0067] R ４０ The monovalent organic group having 1 to 40 carbon atoms represented by the formula (1) is R １ A group in which the monovalent organic group having 1 to 20 carbon atoms shown in the above formula is extended to have 40 carbon atoms can be suitably used.

[0068] R ｆ２１ and R ｆ２２ The monovalent fluorinated hydrocarbon group represented by the formula (1) is R １ Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms shown in the following formula (I) include groups in which some or all of the hydrogen atoms have been substituted with fluorine atoms.

[0069] Specific examples of the anion of the onium salt compound (P1) include, but are not limited to, structures of the following formulae:

[0070]

[0071]

[0072]

[0073] Z of the onium salt compound (P1) ２ ＋ Specific examples of the radiation-sensitive onium cation represented by the formula (I) are not limited to, but include the cation moiety in the onium salt compound (1) above, as well as triarylsulfonium cations, diaryliodonium cations, and radiation-sensitive onium cations that are readily available on the market.

[0074] The onium salt compound (P1) may have a structure in which the above anion and the above radiation-sensitive onium cation are combined in any order.

[0075] The onium salt compound (P1) is not limited, but examples thereof include compounds represented by the following formula:

[0076]

[0077]

[0078] <Nonionic Radiation-Sensitive Acid Generator (P2)> Examples of the nonionic radiation-sensitive acid generator (P2) include a compound represented by the following formula (P2-1) and a compound represented by the following formula (P2-2).

[0079] (In the above formula (P2-1), R ５１ is a divalent hydrocarbon group having 1 to 10 carbon atoms, and R ５２ is a monovalent organic group having 1 to 20 carbon atoms.

[0080] (In the above formula (P2-2), R ５３ are each independently a monovalent organic group having 1 to 20 carbon atoms.

[0081] The above R ５１ The divalent hydrocarbon group having 1 to 10 carbon atoms is R １ Among the monovalent hydrocarbon groups having 1 to 20 carbon atoms in the above formula, groups in which one hydrogen atom has been removed from the group having the corresponding carbon number can be suitably used. ５１ As the alkylene group, an alkylene group having 1 to 3 carbon atoms and a cycloalkylene group containing a cyclic skeleton having an unsaturated bond are preferred.

[0082] The above R ５２ The monovalent organic group having 1 to 20 carbon atoms is R １ A monovalent organic group having 1 to 20 carbon atoms in the formula R ５２ The alkyl group preferably has at least one structure selected from the group consisting of an alicyclic structure having 6 or more carbon atoms, a chain structure having 6 or more carbon atoms, an ester bond, and a halogen atom.

[0083] The above R ５３ The monovalent organic group having 1 to 20 carbon atoms is R １ A monovalent organic group having 1 to 20 carbon atoms in the formula R ５３ It is preferable that the alkyl group has at least one structure selected from the group consisting of an alicyclic structure and an ether bond.

[0084] The alicyclic structure may be R１ A structure corresponding to the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms in the above formula can be suitably employed.

[0085] Examples of the compounds represented by the above formula (P2-1) or (P2-2) include the following structures.

[0086]

[0087] (Polymer) The polymer (hereinafter also referred to as "base polymer") can be appropriately selected depending on the radiation used during exposure for pattern formation. The polymer contains, as a main structural unit, a structural unit (I) having an acid-dissociable group, a structural unit (IV) having a phenolic hydroxyl group, etc. The main structural unit refers to the structural unit that is contained in the highest proportion among the structural units constituting the polymer. The polymer may contain structural units other than the structural units (I) and (IV). Each structural unit will be described below.

[0088] [Structural Unit (I)] The structural unit (I) is a structural unit containing an acid-dissociable group. 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 dissociates under the action of an acid. The radiation-sensitive composition has excellent pattern formability due to the polymer containing the structural unit (I).

[0089] The structural unit (I) is not particularly limited as long as it contains 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 (A1) (hereinafter, also referred to as "structural unit (I-1)") is preferred:

[0090] (In the above formula (A1), R α is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ａ１ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. Ａ２ and R Ａ３are each independently a monovalent chain hydrocarbon group having 1 to 20 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or R Ａ２ and R Ａ３ are combined together with the carbon atoms to which they are bonded to form a divalent alicyclic group having 3 to 20 carbon atoms. m11 and m12 are each independently 0 or 1. However, when m11 is 1, m12 is 1. When m11 is 0, L Ａ１ represents a single bond or a divalent linking group; when m11 is 1, L Ａ１ is a divalent linking group.

[0091] In the above formula (A1), L Ａ１ Examples of the divalent linking group represented by the formula (I) include an alkanediyl group, a cycloalkanediyl group, an alkenediyl group, an arenediyl group, and groups having —CO—, —CS—, —O—, —S—, —SO— between the carbon-carbon bonds of these groups. ２ Examples include -, -NR'-, or a group containing a combination of two or more of these, or a group combining these. R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. Some or all of the hydrogen atoms in these groups may be substituted with, for example, 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; an acyloxy group, or a group in which the hydrogen atoms of these groups have been substituted with halogen atoms.

[0092] The alkanediyl group is preferably an alkanediyl group having 1 to 8 carbon atoms, such as a methanediyl group, an ethanediyl group, a 1,3-propanediyl group, or a 2,2-propanediyl group.

[0093] Examples of the cycloalkanediyl group include monocyclic cycloalkanediyl groups such as cyclopentanediyl and cyclohexanediyl groups, and polycyclic cycloalkanediyl groups such as norbornanediyl and adamantanediyl groups. The cycloalkanediyl group is preferably a cycloalkanediyl group having 5 to 12 carbon atoms.

[0094] Examples of the alkenediyl group include an ethenediyl group, a propenediyl group, a butenediyl group, etc. The alkenediyl group is preferably an alkenediyl group having 2 to 6 carbon atoms.

[0095] Examples of the arenediyl group include a benzenediyl group, a toluenediyl group, a naphthalenediyl group, etc. The arenediyl group is preferably an arenediyl group having 6 to 15 carbon atoms.

[0096] The above R Ａ１ Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a chain hydrocarbon group having 1 to 20 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.

[0097] R Ａ１ ~R Ａ３ Examples of the monovalent linear hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a monovalent linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms, or a monovalent linear or branched unsaturated hydrocarbon group having 2 to 20 carbon atoms. Examples of the monovalent linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a 2-methylpropyl group, a 1-methylpropyl group, a t-butyl group, an n-pentyl group, an isopentyl group, and a neopentyl group. Examples of the monovalent linear or branched unsaturated hydrocarbon group having 2 to 20 carbon atoms include alkenyl groups such as an ethenyl group, a propenyl group, and a butenyl group; and alkynyl groups such as an ethynyl group, a propynyl group, and a butynyl group.

[0098] The above R Ａ１ ~R Ａ３Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (I) include monocyclic or polycyclic saturated hydrocarbon groups, and monocyclic or polycyclic unsaturated hydrocarbon groups. Examples of monocyclic saturated hydrocarbon groups include cycloalkyl groups such as cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. Examples of polycyclic saturated hydrocarbon groups include bridged alicyclic hydrocarbon groups such as norbornyl, adamantyl, tricyclodecyl, and tetracyclododecyl. Examples of monocyclic unsaturated hydrocarbon groups include monocyclic cycloalkenyl groups such as cyclopropenyl, cyclobutenyl, cyclopentenyl, and cyclohexenyl. Examples of polycyclic unsaturated hydrocarbon groups include polycyclic cycloalkenyl groups such as norbornenyl, tricyclodecenyl, and tetracyclododecenyl. The bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two carbon atoms that are not adjacent to each other among the carbon atoms that constitute the alicyclic ring are linked by a linking group containing one or more carbon atoms.

[0099] The above R Ａ１ Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by the formula (I) include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group; and aralkyl groups such as a benzyl group, a phenethyl group, and a naphthylmethyl group.

[0100] The above R Ａ１ As the alkyl group, a linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms, or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms is preferred.

[0101] R Ａ２ and R Ａ３ As the divalent alicyclic group having 3 to 20 carbon atoms constituted by combining these together with the carbon atoms to which they are bonded, a group in which one hydrogen atom has been removed from the above-mentioned monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms can be suitably used.

[0102] R Ａ２ and R Ａ３ is a monovalent chain hydrocarbon group having 1 to 10 carbon atoms, or R Ａ２ and R Ａ３are combined together together with the carbon atoms to which they are bonded, and a divalent alicyclic group having 3 to 20 carbon atoms is preferred, a monovalent linear hydrocarbon group having 1 to 10 carbon atoms or a divalent alicyclic group having 5 to 10 carbon atoms is more preferred, and as the monovalent linear hydrocarbon group having 1 to 10 carbon atoms or the divalent alicyclic group having 5 to 10 carbon atoms, a methyl group, an ethyl group, an isopropyl group, a tert-butyl group, a cyclopentanediyl group, a cyclohexanediyl group, or an adamantanediyl group is even more preferred.

[0103] When m11 is 0, L Ａ１ is preferably a single bond or an arenediyl group. Ａ１ is preferably an alkanediyl group.

[0104] Examples of the structural unit (I) include structural units represented by the following formulas (A1-1) to (A1-14) (hereinafter also referred to as "structural units (I-1) to (I-14)").

[0105]

[0106]

[0107] In the above formulas (A1-1) to (A1-14), R α , R Ａ１ ~R Ａ３ has the same meaning as formula (A1) above. X is a hydroxy group, a halogen atom, 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 0 or 1. a1 is an integer of 0 to 3. When a1 is 2 or more, multiple Xs are the same or different. a4 is an integer of 1 to 3.

[0108] i and j are preferably 1 or 2. k and l are preferably 1. R Ａ１ R is preferably a methyl group, an ethyl group, an isopropyl group, a t-butyl group, a phenyl group, or an iodophenyl group. Ａ２ and R Ａ３As X, a methyl group, an ethyl group, or an isopropyl group is preferable. As X, a hydroxy group, an iodine atom, or an alkyl group is preferable.

[0109] The polymer (A) may contain a structural unit represented by the following formula (B1) as the structural unit (I).

[0110] (In the above formula (B1), R α has the same meaning as in formula (A1). Ｂ１ , R Ｂ２ and R Ｂ３ are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms.

[0111] R Ｂ１ , R Ｂ２ and R Ｂ３ The monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (A1) is Ａ１ A monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the following formula can be preferably used. Ｂ１ , R Ｂ２ and R Ｂ３ As the alkyl group, a monovalent chain hydrocarbon group having 1 to 20 carbon atoms is preferred, a monovalent alkyl group having 1 to 10 carbon atoms is more preferred, and a methyl group or an ethyl group is even more preferred.

[0112] Furthermore, the polymer (A) may contain, as the structural unit (I), structural units represented by the following formulae (1f) to (2f).

[0113]

[0114] 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. h1 is an integer of 1 to 4.

[0115] The above R βｆ is preferably a hydrogen atom, a methyl group or an ethyl group. h1 is preferably 1 or 2.

[0116] The base polymer may contain one type of structural unit (I) or a combination of two or more types.

[0117] When the base polymer has the structural unit (I) having the acid-dissociable group, the lower limit of the content of the structural unit (I) (the total content when multiple types are included) 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 the content is preferably 80 mol%, more preferably 70 mol%, and even more preferably 65 mol%. By setting the content of the structural unit (I) within the above range, the pattern formability of the radiation-sensitive composition can be further improved.

[0118] [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.

[0119] Examples of the structural unit (II) include structural units represented by the following formulae (T-1) to (T-11).

[0120]

[0121] 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, or a dimethylamino 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. k is an integer of 0 to 3. m is an integer of 1 to 3.

[0122] The above R Ｌ４ and R Ｌ５ The 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.

[0123] 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-.

[0124] Of these, as the structural unit (II), a structural unit containing a lactone structure is preferable, a structural unit containing a γ-butyrolactone structure or a norbornane lactone structure is more preferable, and a structural unit derived from γ-butyrolactone-yl (meth)acrylate or norbornane lactone-yl (meth)acrylate is even more preferable.

[0125] When the base polymer has the structural unit (II), 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 5 mol%, more preferably 10 mol%, and even more preferably 15 mol%. The upper limit of the content is preferably 70 mol%, more preferably 60 mol%, and even more preferably 50 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.

[0126] [Structural Unit (III)] The structural unit (III) is a structural unit containing a polar group (excluding those corresponding to the structural unit (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 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.

[0127] Examples of the structural unit (III) include structural units represented by the following formula:

[0128]

[0129]

[0130] In the above formula, R Ａ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0131] 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 2 mol%, more preferably 6 mol%, and even more preferably 10 mol%. The upper limit of the content is preferably 40 mol%, more preferably 30 mol%, and even more preferably 25 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.

[0132] [Structural Unit (IV)] The structural unit (IV) is a structural unit having a phenolic hydroxyl group. The structural unit (IV) contributes to improving etching resistance and the difference in developer solubility between exposed and unexposed areas (dissolution contrast). In particular, the polymer is suitable for pattern formation using exposure to radiation having a wavelength of 50 nm or less, such as a KrF excimer laser, an electron beam, or EUV. In this case, the polymer preferably has the structural unit (I) in addition to the structural unit (IV).

[0133] The structural unit (IV) is represented by, for example, the following formulas (4-1) to (4-6).

[0134]

[0135] In the above formulas (4-1) to (4-6), R ４１ are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Y is a halogen atom, a trifluoromethyl group, a cyano group, an alkyl group or an alkoxy group having 1 to 6 carbon atoms, or an acyl group, acyloxy group, or alkoxycarbonyl group having 2 to 7 carbon atoms. When there are multiple Ys, the multiple Ys may be the same or different. t is an integer of 0 to 4.

[0136] In order to obtain the structural unit (IV), it is preferable to carry out polymerization 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. Alternatively, a monomer that gives the structural unit (IV) may be polymerized without protecting the phenolic hydroxyl group.

[0137] In the case of a polymer for exposure to a KrF excimer laser or radiation having a wavelength of 50 nm or less, the content of the structural unit (IV) (the total content when multiple types are contained) is preferably 10 mol % and more preferably 20 mol % relative to all structural units constituting the polymer, and the upper limit of the content is preferably 80 mol %, more preferably 70 mol %.

[0138] [Other Structural Units] The base polymer may contain a structural unit having a hydrocarbon group represented by the following formula (6) (hereinafter also referred to as "structural unit (VII)") as a structural unit other than the structural units listed above. (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 hydrocarbon group having 1 to 20 carbon atoms.

[0139] In the above formula (6), R ２α The monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (1) is１ A monovalent hydrocarbon group having 1 to 20 carbon atoms in the above formula can be suitably used.

[0140] When the base polymer contains the structural unit (VII), the lower limit of the content of the structural unit (VII) (the total content when multiple types are contained) is preferably 2 mol%, more preferably 5 mol%, and even more preferably 8 mol%, based on all structural units constituting the base polymer, and the upper limit of the content is preferably 80 mol%, more preferably 70 mol%, and even more preferably 60 mol%.

[0141] When the base polymer is for exposure using a KrF excimer laser, in addition to the above structural units, it may also contain structural units derived from (meth)acrylic acid.When the base polymer contains the structural units derived from (meth)acrylic acid, the lower limit of the content ratio of the structural units derived from (meth)acrylic acid (when multiple types are contained, the total content ratio) is preferably 1 mol%, more preferably 2 mol%, and even more preferably 3 mol% relative to the total structural units constituting the base polymer.Furthermore, the upper limit of the content ratio is preferably 15 mol%, more preferably 10 mol%, and even more preferably 8 mol%.

[0142] (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.

[0143] 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. Of 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.

[0144] 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, i-butyl acetate, and methyl propionate; lactones such as γ-butyrolactone and δ-valerolactone; polyhydric alcohol partial ether acetate solvents such as diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate; Examples of the solvent include ketones such as acetone, methyl ethyl ketone, 2-butanone, 4-methyl-2-pentanone, 2-heptanone, and cyclohexanone; chain ethers such as dimethoxyethanes and diethoxyethanes; cyclic ethers such as tetrahydrofuran and 1,4-dioxanes; polyhydric alcohol partial ethers such as 1-methoxy-2-propanol (propylene glycol monomethyl ether); and alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 4-methyl-2-pentanol, and 1-methoxy-2-propanol. These solvents used in the polymerization may be used alone or in combination of two or more.

[0145] 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.

[0146] 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 2,000, more preferably 3,000, even more preferably 4,000, and particularly preferably 4,500. The upper limit of Mw is preferably 30,000, more preferably 20,000, even more preferably 10,000, and particularly preferably 8,000. By setting the Mw of the base polymer within the above range, the resulting resist film can exhibit good heat resistance and developability.

[0147] 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.

[0148] The Mw and Mn of the polymer in this specification are values ​​measured using gel permeation chromatography (GPC) under the following conditions.

[0149] 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

[0150] The content of the base polymer is preferably 60% by mass or more, more preferably 65% ​​by mass or more, and even more preferably 70% by mass or more, based on the total solid content of the radiation-sensitive composition.

[0151] (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.

[0152] The high-fluorine content polymer preferably has, for example, a structural unit represented by the following formula (5) (hereinafter also referred to as "structural unit (V)"), and may also have the structural unit (I), structural unit (III), or structural unit (VII) of the base polymer, as necessary.

[0153]

[0154] 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.

[0155] 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.

[0156] 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.

[0157] 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.

[0158] 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.

[0159] The above R １４As 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.

[0160] When the high-fluorine-content polymer has the structural unit (V), the lower limit of the content of the structural unit (V) (the total content when multiple types are contained) relative to all structural units constituting the high-fluorine-content polymer is preferably 50 mol%, more preferably 60 mol%, and even more preferably 70 mol%. The upper limit of this 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.

[0161] 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 (VI), the high-fluorine content polymer has improved solubility in an alkaline developer, and can suppress the occurrence of development defects.

[0162]

[0163] 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 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 At the end of the side, there is an oxygen atom, a sulfur atom, and -NR ｄｄR 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.

[0164] When the structural unit (VI) has an alkali-soluble group (x), R Ｆ is 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.

[0165] 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-*. 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. １is 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. １ is 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.

[0166] 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.

[0167] R Ｅ When is a divalent organic group, it is preferably a group having a lactone structure, more preferably a group having a polycyclic lactone structure, and even more preferably a group having a norbornane lactone structure.

[0168] When the high-fluorine-content polymer has the structural unit (VI), the lower limit of the content of the structural unit (VI) (the total content when multiple types are contained) relative to all structural units constituting the high-fluorine-content polymer is preferably 40 mol%, more preferably 50 mol%, and even more preferably 55 mol%. 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 (VI) within the above range, it is possible to increase the water repellency of the resist film during immersion exposure and to improve the solubility in an alkaline developer, thereby suppressing the occurrence of development defects.

[0169] [Other Structural Units] The high fluorine content polymer may contain, as a structural unit other than the structural units listed above, the structural unit (VII) in addition to the structural unit (I) and the structural unit (III) in the base polymer.

[0170] When the high-fluorine content polymer contains the structural unit (I), the structural unit (III), or the structural unit (VII), the content ratio of each structural unit in the high-fluorine content polymer can suitably be the content ratio described for the base polymer.

[0171] The lower limit of Mw of the high fluorine content polymer is preferably 2,000, more preferably 4,000, and even more preferably 5,000. The upper limit of Mw is preferably 20,000, more preferably 12,000, and even more preferably 8,000.

[0172] 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.

[0173] When the radiation-sensitive composition contains a high-fluorine-containing polymer, the content of the high-fluorine-containing polymer is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 1.5 parts by mass or more, relative to 100 parts by mass of the base polymer, and is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 8 parts by mass or less.

[0174] 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.

[0175] (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.

[0176] (Acid Diffusion Controller) The radiation-sensitive composition may contain an acid diffusion controller, if necessary. The acid diffusion controller controls the diffusion phenomenon in the resist film of the acid generated from the onium salt compound (1) upon exposure, thereby suppressing undesirable chemical reactions in unexposed areas. The storage stability of the resulting radiation-sensitive composition is also improved. Furthermore, the resolution of the resist pattern is further improved, and changes in the line width of the resist pattern due to variations in the incubation time from exposure to development can be suppressed, resulting in a radiation-sensitive composition with excellent process stability.

[0177] Examples of the acid diffusion controller include a compound represented by the following formula (7) (hereinafter also referred to as "nitrogen-containing compound (I)"), a compound having two nitrogen atoms in the same molecule (hereinafter also referred to as "nitrogen-containing compound (II)"), a compound having three nitrogen atoms (hereinafter also referred to as "nitrogen-containing compound (III)"), an amide group-containing compound, a urea compound, and a nitrogen-containing heterocyclic compound.

[0178]

[0179] In the above formula (7), R ２２ , R ２３ and R ２４ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group.

[0180] Examples of the nitrogen-containing compound (I) include monoalkylamines such as n-hexylamine; dialkylamines such as di-n-butylamine; trialkylamines such as triethylamine; and aromatic amines such as aniline and 2,6-di-i-propylaniline.

[0181] Examples of the nitrogen-containing compound (II) include ethylenediamine and N,N,N',N'-tetramethylethylenediamine.

[0182] Examples of the nitrogen-containing compound (III) include polyamine compounds such as polyethyleneimine and polyallylamine; and polymers such as dimethylaminoethylacrylamide.

[0183] Examples of the amide group-containing compound include formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, benzamide, pyrrolidone, and N-methylpyrrolidone.

[0184] Examples of the urea compound include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, and tributylthiourea.

[0185] Examples of the nitrogen-containing heterocyclic compound include pyridines such as pyridine and 2-methylpyridine; morpholines such as N-propylmorpholine and N-(undecylcarbonyloxyethyl)morpholine; pyrazine, pyrazole, and the like.

[0186] The nitrogen-containing organic compound is preferably a compound having an acid-dissociable group. Examples of such nitrogen-containing organic compounds having an acid-dissociable group include N-t-butoxycarbonylpiperidine, N-t-butoxycarbonylimidazole, N-t-butoxycarbonylbenzimidazole, N-t-butoxycarbonyl-2-phenylbenzimidazole, N-(t-butoxycarbonyl)di-n-octylamine, N-(t-butoxycarbonyl)diethanolamine, N-(t-butoxycarbonyl)dicyclohexylamine, N-(t-butoxycarbonyl)diphenylamine, N-t-butoxycarbonyl-4-hydroxypiperidine, N-t-butoxycarbonyl-4-acetoxypiperidine, and N-t-amyloxycarbonyl-4-hydroxypiperidine.

[0187] Furthermore, a radiation-sensitive weak acid generator that generates a weak acid upon exposure can also be suitably used as the acid diffusion controller. The acid generated by the radiation-sensitive weak acid generator is a weak acid that does not induce dissociation of the acid-dissociable group in the polymer under conditions that dissociate the acid-dissociable group. In this specification, "dissociation" of the acid-dissociable group refers to dissociation upon post-exposure baking at 110°C for 60 seconds.

[0188] Examples of the radiation-sensitive weak acid generator include onium salt compounds that decompose upon exposure to light and lose their ability to control acid diffusion. Examples of the onium salt compound include sulfonium salt compounds represented by the following formula (8-1) and iodonium salt compounds represented by the following formula (8-2). Other examples include compounds containing a sulfonium cation and an anion in the same molecule represented by the following formula (8-3), and compounds containing an iodonium cation and anion in the same molecule represented by the following formula (8-4).

[0189]

[0190] In the above formulas (8-1) to (8-4), J ＋ is a sulfonium cation, and U ＋ is an iodonium cation. ＋ Examples of the sulfonium cation represented by the formula (I) include a triarylsulfonium cation, and examples of the sulfonium cation represented by the formula (I) include a triarylsulfonium cation.＋ Examples of the iodonium cation represented by the formula (I) include diaryliodonium cations. － and Q － are each independently OH － , R α -COO － , R α -SO ３ － It is an anion represented by R α is a single bond or a monovalent organic group having 1 to 30 carbon atoms. Examples of this organic group include a monovalent hydrocarbon group having 1 to 20 carbon atoms, a group having a divalent heteroatom-containing group between carbon atoms of this hydrocarbon group or at the carbon chain end, a group in which some or all of the hydrogen atoms of the hydrocarbon group have been substituted with a monovalent heteroatom-containing group, or a combination thereof.

[0191] The monovalent hydrocarbon group having 1 to 20 carbon atoms includes R １ A monovalent hydrocarbon group having 1 to 20 carbon atoms in the above formula can be suitably used.

[0192] 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.

[0193] Examples of the divalent heteroatom-containing group include -CO-, -CS-, -NH-, -O-, -S-, -SO-, and -SO ２ -, or a group in which these are combined.

[0194] Examples of the monovalent heteroatom-containing group include a hydroxy group, a sulfanyl group, a cyano group, a nitro group, and a halogen atom.

[0195] Examples of the radiation-sensitive weak acid generator include compounds represented by the following formula:

[0196]

[0197]

[0198] Of these, the radiation-sensitive weak acid generator is preferably a sulfonium salt, more preferably a triarylsulfonium salt, and even more preferably triphenylsulfonium carboxylate or triphenylsulfonium sulfonate.

[0199] The lower limit of the content of the acid diffusion controller is preferably 0.01 parts by mass, more preferably 0.02 parts by mass, and even more preferably 0.03 parts by mass, relative to 100 parts by mass of the polymer, and the upper limit of the content is preferably 30 parts by mass, more preferably 20 parts by mass, and even more preferably 15 parts by mass.

[0200] By setting the content of the acid diffusion controller within the above range, the lithography performance of the radiation-sensitive composition can be further improved. The radiation-sensitive composition may contain one or more types of acid diffusion controller.

[0201] (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) and the polymer, as well as an optional acid diffusion controller and the like.

[0202] Examples of the solvent include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

[0203] Examples of alcohol-based solvents include monoalcohol-based solvents having 1 to 18 carbon atoms, such as iso-propanol, 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 have been etherified, such as propylene glycol monomethyl ether. In the present embodiment, alcoholic acid ester solvents such as methyl lactate, ethyl lactate, propyl lactate, butyl lactate, methyl 2-hydroxyisobutyrate, i-propyl 2-hydroxyisobutyrate, i-butyl 2-hydroxyisobutyrate, and n-butyl 2-hydroxyisobutyrate are also included in the alcoholic solvents.

[0204] 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 (partial) ether-based solvents obtained by etherifying the hydroxy groups of the above-mentioned polyhydric alcohol-based solvents.

[0205] Examples of ketone solvents include chain ketone solvents such as acetone, butanone, and methyl-iso-butyl ketone; cyclic ketone solvents such as cyclopentanone, cyclohexanone, and methylcyclohexanone; 2,4-pentanedione, acetonylacetone, and acetophenone.

[0206] 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.

[0207] 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.

[0208] Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; and aromatic hydrocarbon solvents such as benzene, toluene, di-isopropylbenzene, and n-amylnaphthalene.

[0209] Among these, alcohol-based solvents, ester-based solvents, and ether-based solvents are preferred, alcohol acid ester-based solvents, polyhydric alcohol partial ether acetate-based solvents, polyhydric alcohol (partial) ether-based solvents, lactone-based solvents, and ketone-based solvents are more preferred, and ethyl lactate, propylene glycol monomethyl ether acetate, γ-butyrolactone, propylene glycol monomethyl ether, and cyclohexanone are even more preferred. The radiation-sensitive composition may contain one or more solvents.

[0210] (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 radiation-sensitive acid generator other than the onium salt compound (1), a crosslinking agent, a localization promoter, a surfactant, an alicyclic skeleton-containing compound, and a sensitizer. With regard to these other optional components, a perfluoromethyl group (—CF ３ ) or a perfluoromethylene group (—CF ２ It is preferable that the other optional components do not contain any of the following: One kind of these optional components may be used alone or two or more kinds of these optional components may be used in combination.

[0211] <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.

[0212] <Pattern Forming Method> A pattern forming method according to one embodiment of the present invention includes the steps 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"); exposing the resist film (hereinafter also referred to as an "exposing step"); and developing the exposed resist film (hereinafter also referred to as a "developing step").

[0213] According to the above-mentioned method for forming a resist pattern, a high-quality resist pattern can be efficiently formed because the above-mentioned radiation-sensitive composition is used, which has good storage stability and is capable of exhibiting excellent sensitivity, pattern rectangularity, pattern circularity, exposure latitude, depth of focus, development defect suppression, LWR, and CDU during pattern formation. Each step will be described below.

[0214] [Resist Film Formation Step] In this step, a resist film is formed from the radiation-sensitive composition. Examples of substrates on which this 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 70°C to 150°C, preferably 90°C to 140°C. The PB time is typically 5 to 600 seconds, preferably 10 to 300 seconds.

[0215] The lower limit of the film thickness of the resist film to be formed is preferably 10 nm, more preferably 15 nm, and even more preferably 20 nm. The upper limit of the film thickness is preferably 500 nm, more preferably 400 nm, and even more preferably 300 nm. When exposure is performed with a KrF excimer laser in the exposure step described below, the lower limit of the film thickness may be 500 nm, 800 nm, or 1200 nm (1.2 μm). The upper limit of the film thickness may be 10 μm, 6 μm, or 4 μm.

[0216] 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 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.

[0217] When the subsequent exposure step is carried out using a KrF excimer laser or radiation with a wavelength of 50 nm or less, it is preferable to use a polymer having the structural units (I) and (IV) as the base polymer in the composition.

[0218] [Exposure Step] In this step, the resist film formed in the resist film formation step 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, and ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), electron beams, and EUV are more preferred.

[0219] 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.

[0220] 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 160°C, preferably 80°C to 130°C. The PEB time is typically 5 seconds to 600 seconds, preferably 10 seconds to 300 seconds.

[0221] [Development Step] In this step, the resist film exposed in the exposure step 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.

[0222] In the case of alkaline development, examples of the developer used in the development include 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, and 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, an aqueous TMAH solution is preferred, and a 2.38% by mass aqueous TMAH solution is more preferred.

[0223] 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 ether solvents, glycol ether solvents are preferred, with ethylene glycol monomethyl ether and propylene glycol monomethyl ether being more preferred. As ester solvents, acetate ester solvents are preferred, with n-butyl acetate and amyl acetate being more preferred. As ketone solvents, chain ketones are preferred, with 2-heptanone being 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.

[0224] 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.

[0225] 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).

[0226] <Onium Salt Compound> The onium salt compound according to this embodiment is a compound represented by the following formula (1). (In formula (1), R ｆ is a halogen atom or a cyano group. n is an integer of 0 to 4. When n is 2 or more, multiple R ｆ are the same or different. １ is R １ and the carbon atom to which ＊ -COO-, ＊ -OCO-, ＊ -SO ２ -, ＊ -S-, ＊ -CO-, ＊ —O—CO—O—, ＊ -CONR'- or ＊ A monovalent organic group having 1 to 20 carbon atoms, a hydrogen atom, a halogen atom, a cyano group, or a fluorinated alkyl group bonded via —NR′CO—. Each R′ is independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. ＊ is R １ is a bond to the carbon atom to which it is bonded. However, when n is 0, R １ is a halogen atom or a cyano group. ２ is a hydroxy group, a nitro group, an amino group, a carboxy group, or a monovalent organic group having 1 to 20 carbon atoms. m is an integer of 0 to 4. When m is 2 or more, multiple R ２are the same or different. n+m is an integer of 0 to 4. Ar is a monovalent organic group having an aromatic ring with 5 to 40 ring members. X is a methylene group, —O—, —CO—, or —SO ２ However, when X is a methylene group, the aromatic ring of Ar and S in the formula ＋ and are directly bonded, and R １ does not contain a polymerizable group. ４１ , R ４２ , R ４３ , R ４４ , R ４５ and R ４８ are each independently a hydrogen atom, a hydroxy group, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms. ４６ and R ４７ are each independently a hydrogen atom, a hydroxy group, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms, or R ４６ and R ４７ represents a ring structure having 3 to 10 ring members formed by combining together with the two carbon atoms to which they are attached.

[0227] As the onium salt compound, the onium salt compound (1) contained in the radiation-sensitive composition can be suitably used.

[0228] 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.

[0229] [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.

[0230] [ 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.).

[0231] <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 %.

[0232]

[0233] Synthesis Example 1 Synthesis of Polymer (A-1) Monomer (M-1), monomer (M-4), and monomer (M-17) were dissolved in 1-methoxy-2-propanol (200 parts by mass) to a molar ratio of 60 / 30 / 10 (mol %), and AIBN (5 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 separated by filtration. The white powder collected by filtration was washed twice with hexane, filtered, and then 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 collected by filtration and dried at 50°C for 13 hours to obtain a white powdery polymer (A-1) (yield: 80%). The Mw of the polymer (A-1) was 7,100, 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-4) and (M-17) were 60.2 mol %, 30.0 mol % and 9.8 mol %, respectively.

[0234] [Synthesis Examples 2 to 9] (Synthesis of Polymers (A-2) to (A-9)) Polymers (A-2) to (A-9) 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. Note that the monomer that gives the structural unit (IV) in the polymers is １３ C-NMR analysis confirmed that the peaks of the carbonyl groups of the acetyl groups had disappeared, indicating 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 1 below. In Table 1 below, "-" indicates that the corresponding component was not used (the same applies to the following tables).

[0235]

[0236] Synthesis Example 10 Synthesis of Polymer (A-10) Monomer (M-6) and monomer (M-2) were dissolved in 1-methoxy-2-propanol (200 parts by mass) to give a molar ratio of 50 / 50 (mol %), and AIBN (5 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 with water to below 30°C. The cooled polymerization solution was poured into hexane (2,000 parts by mass), and the precipitated white powder was filtered off. The white powder separated by filtration was washed twice with hexane, filtered off, and dissolved in 1-methoxy-2-propanol (300 parts by mass). Next, methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were 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-10) (yield: 81%). The Mw of the polymer (A-10) was 5,500, and the Mw / Mn was 1.62. １３As a result of C-NMR analysis, the content ratios of the structural units derived from (M-6) and (M-2) were 50.2 mol % and 49.8 mol %, respectively.

[0237] [Synthesis Examples 11 to 13] (Synthesis of Polymers (A-11) to (A-13)) Polymers (A-11) to (A-13) were synthesized in the same manner as in Synthesis Example 10, 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) in the polymer 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.

[0238]

[0239] Synthesis Example 14 Synthesis of Polymer (A-14) Monomer (M-5), monomer (M-6), monomer (M-12), and monomer (M-13) were dissolved in 2-butanone (200 parts by mass) to give a molar ratio of 10 / 50 / 20 / 20 (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 separated by filtration. The white powder collected by filtration was washed twice with methanol, filtered, and dried at 50°C for 24 hours to obtain a white powdery polymer (A-14) (yield: 85%). The Mw of the polymer (A-14) was 7,100, and the Mw / Mn was 1.61. １３ As a result of C-NMR analysis, the contents of the structural units derived from (M-5), (M-6), (M-12) and (M-13) were 8.3 mol%, 50.8 mol%, 20.5 mol%, and 20.4 mol%, respectively.

[0240] [Synthesis Examples 15 and 16] (Synthesis of Polymer (A-15) and Polymer (A-16)) Polymer (A-15) and Polymer (A-16) were synthesized in the same manner as in Synthesis Example 14, except that the types and blending ratios of monomers shown in Table 3 below were used. The content (mol %) of each structural unit and physical properties (Mw and Mw / Mn) of the obtained polymers are also shown in Table 3 below.

[0241]

[0242] Synthesis Example 17 Synthesis of High Fluorine Content Polymer (F-1) Monomer (M-6) and monomer (M-19) were dissolved in 2-butanone (200 parts by mass) to give a molar ratio of 20 / 80 (mol %), and AIBN (4 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 polymerized solution was cooled with water to below 30°C. 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 operation was repeated three times. The solvent was replaced with propylene glycol monomethyl ether acetate, yielding a solution of high fluorine content polymer (F-1) (yield: 75%). The high fluorine content polymer (F-1) had an Mw of 6,200 and an Mw / Mn ratio of 1.77. １３ As a result of C-NMR analysis, the content ratios of the structural units derived from (M-6) and (M-19) were 19.5 mol % and 80.5 mol %, respectively.

[0243] Synthesis Examples 18 and 19 Synthesis of high fluorine content polymer (F-2) and high fluorine content polymer (F-3) High fluorine content polymer (F-2) and high fluorine content polymer (F-3) were synthesized in the same manner as in Synthesis Example 17, except that the types and blending ratios of monomers shown in Table 4 below were used. The content (mol %) of each structural unit and physical properties (Mw and Mw / Mn) of the obtained polymers are also shown in Table 4 below.

[0244]

[0245] Synthesis Example 20 Synthesis of Radiation-Sensitive Acid-Generating Polymer (PP-1) Monomer (M-1), monomer (M-4), and monomer (M-22) were dissolved in 1-methoxy-2-propanol (200 parts by mass) so that the molar ratio was 60 / 35 / 5 (mol %), and AIBN (5 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 with water to below 30°C. The cooled polymerization solution was poured into hexane (2,000 parts by mass), and the precipitated white powder was separated by filtration. The white powder collected by filtration was washed twice with hexane, filtered, and then 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 collected by filtration and dried at 50°C for 13 hours to obtain a white powdery polymer (PP-1) (yield: 80%). The Mw of the polymer (PP-1) was 7,100, 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-4) and (M-22) were 60.2 mol %, 35.0 mol % and 4.8 mol %, respectively.

[0246] <Synthesis of Radiation-Sensitive Acid Generator [B]> An onium salt compound (1) represented by the following formula was synthesized as the radiation-sensitive acid generator [B].

[0247]

[0248]

[0249] Example B1 Synthesis of Compound (B-1) Compound (B-1) was synthesized according to the following synthesis scheme.

[0250]

[0251] 20.0 mmol of iodine, 40.0 mmol of tert-butylbenzene, 40.0 mmol of metachloroperbenzoic acid (mCPBA), 40.0 mmol of tosylic acid monohydrate (pTsOH), and 100 g of chloroform were added to a reaction vessel and stirred at room temperature for 24 hours. After that, the mixture was diluted with water, extracted with methylene chloride, and the organic layer was separated. The resulting organic layer was washed with a saturated aqueous sodium chloride solution. After drying with sodium sulfate, the solvent was distilled off, and the mixture was recrystallized and purified with diethyl ether to obtain the salt represented by the above formula (B-1-a) in good yield.

[0252] 20.0 mmol of a sodium sulfonate compound was added to the salt represented by formula (B-1-a) above, and a mixed solution of water:dichloromethane (1:1 (mass ratio)) was added to prepare a 0.5 M solution. After vigorously stirring at room temperature for 3 hours, dichloromethane was added for extraction, and the organic layer was separated. The obtained organic layer was dried over sodium sulfate, the solvent was distilled off, and the mixture was purified by column chromatography to obtain the salt represented by formula (B-1-b) above in good yield.

[0253] To the salt represented by formula (B-1-b) were added 20.0 mmol of 1,4-thioxane, 2.00 mmol of copper (II) acetate, and 50 g of chloroform, followed by stirring at room temperature for 24 hours. After removing impurities by filtration through Celite, the solvent was distilled off, and the residue was purified by column chromatography to obtain compound (B-1) represented by formula (B-1) in good yield.

[0254] [Examples B2 to B20 and B25 to B27] (Synthesis of Compounds (B-2) to (B-20) and (B-25) to (B-27)) Radiation-sensitive acid generators represented by the following formulas (B-2) to (B-20) and (B-25) to (B-27) were synthesized in the same manner as in Example B1, except that the raw materials and precursors were appropriately changed.

[0255]

[0256]

[0257] Example B21 Synthesis of Compound (B-21) Compound (B-21) was synthesized according to the following synthesis scheme.

[0258]

[0259] 20.0 mmol of the ketone compound, 25.0 mmol of trimethylsilyl chloride (TMSCl), 30.0 mmol of triethylamine, and 100 g of chloroform were added to a reaction vessel and stirred at room temperature for 24 hours. Subsequently, the mixture was diluted with a saturated aqueous ammonium chloride solution, and then extracted with methylene chloride to separate the organic layer. The resulting organic layer was washed with a saturated aqueous sodium chloride solution. After drying with sodium sulfate, the solvent was distilled off, and the compound represented by formula (B-21-a) was obtained in good yield.

[0260] The compound represented by the formula (B-21-a) was treated with 20.0 mmol of 1,4-thioxane-4-oxide and trifluoromethanesulfonic anhydride (Tf ２ 20.00 mmol of HCl (C10) and 50 g of chloroform were added and stirred at room temperature for 24 hours. Thereafter, the mixture was diluted with a saturated aqueous solution of sodium bicarbonate, and then extracted with methylene chloride to separate the organic layer. The resulting organic layer was washed with a saturated aqueous solution of sodium chloride. After drying with sodium sulfate, the solvent was distilled off and the residue was purified by column chromatography to obtain the salt represented by the above formula (B-21-b) in good yield.

[0261] 20.0 mmol of a sodium sulfonate compound was added to the salt represented by formula (B-21-b) above, and a mixed solution of water:dichloromethane (1:1 (mass ratio)) was added to prepare a 0.5 M solution. After vigorously stirring at room temperature for 3 hours, dichloromethane was added for extraction, and the organic layer was separated. The obtained organic layer was dried over sodium sulfate, the solvent was distilled off, and the mixture was purified by column chromatography to obtain the salt represented by formula (B-21) above in good yield.

[0262] [Examples B22 to B24] (Synthesis of Compounds (B-22) to (B-24)) Radiation-sensitive acid generators represented by the following formulas (B-22) to (B-24) were synthesized in the same manner as in Example B21, except that the raw materials and precursors were appropriately changed.

[0263]

[0264] The following compounds were used as components other than the components synthesized above.

[0265] [Radiation-sensitive acid generators other than radiation-sensitive acid generators (B-1) to (B-27)] b-1 to b-17: compounds represented by the following formulas (b-1) to (b-17) (hereinafter, the compounds represented by formulas (b-1) to (b-17) may be referred to as "compound (b-1)" to "compound (b-17)," respectively).

[0266]

[0267] [[C] Acid diffusion controller] C-1 to C-10: Compounds represented by the following formulas (C-1) to (C-10) (hereinafter, the compounds represented by formulas (C-1) to (C-10) may be referred to as "compound (C-1)" to "compound (C-10)," respectively).

[0268]

[0269] [[D] Other Additives] D-1 to D-8: Compounds represented by the following formulas (D-1) to (D-6) and additive compounds (D-7) to (D-8) (hereinafter, compounds (D-1) to (D-8) may be referred to as "compound (D-1)" to "compound (D-8)," respectively).

[0270]

[0271] D-7: MEGAFACE EFS-321 (manufactured by DIC Corporation) (non-fluorine-based) D-8: BYK-399 (manufactured by BYK Japan Co., Ltd.) (non-silicone-based)

[0272] [[E] Solvent] E-1: Propylene glycol monomethyl ether acetate E-2: Cyclohexanone E-3: γ-butyrolactone E-4: Ethyl lactate E-5: Propylene glycol monomethyl ether

[0273] [Preparation of Positive Radiation-Sensitive Composition for KrF Exposure] [Example 1] [A] 100 parts by mass of (A-1) as a polymer, [B] 3.0 parts by mass of (B-1) as a radiation-sensitive acid generator, [C] 0.05 parts by mass of (C-2) as an acid diffusion controller, [D] 0.05 parts by mass of (D-6) as other additives, and [E] 400 parts by mass of a mixed solvent of (E-1) / (E-2) as a solvent were mixed and filtered through a membrane filter having a pore size of 0.2 μm to prepare a radiation-sensitive composition (J-1).

[0274] [Examples 2 to 45, 120 to 126 and Comparative Examples 1 to 9] Radiation-sensitive compositions (J-2) to (J-45), (J-120) to (J-126), and (CJ-1) to (CJ-9) were prepared in the same manner as in Example 1, except that the types and amounts of each component shown in Table 5 below were used.

[0275]

[0276] <Formation of Resist Pattern Using Positive Radiation-Sensitive Composition for KrF Exposure> The positive radiation-sensitive composition for KrF exposure prepared above was applied to a 12-inch silicon wafer that had been treated with hexamethyldisilazane using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT8"), and prebaked at 130°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 3 μm. Next, this resist film was exposed to light through a 250 nm line-and-space mask pattern using a KrF excimer laser scanner (ASML's "PAS5500 / 850C wavelength 248 nm") under optical conditions of NA = 0.68 and σ = 0.60. After exposure, the wafer was subjected to post-exposure bake (PEB) at 130°C for 60 seconds. Thereafter, the resist film was subjected to alkaline development using a 2.38% by mass aqueous solution of TMAH as an alkaline developer, and after development, the resist film was washed with water and further dried to form a positive resist pattern (250 nm line and space pattern).

[0277] <Evaluation> The resist patterns formed using the above-mentioned positive-working radiation-sensitive compositions for KrF exposure were evaluated for sensitivity, pattern rectangularity, storage stability, exposure latitude, number of development defects, and depth of focus according to the methods described below. A scanning electron microscope (CG-5000 manufactured by Hitachi High-Technologies Corporation) was used to measure the length of the resist patterns. The results are shown in Table 6 below.

[0278] [Sensitivity] In forming a resist pattern using the positive-working radiation-sensitive composition for KrF exposure, the exposure amount for forming a 250 nm line and space pattern was defined as the optimum exposure amount, and this optimum exposure amount was defined as the sensitivity (mJ / cm ２ The sensitivity was 45 mJ / cm ２ The following cases are considered "good" and 45 mJ / cm ２ If it exceeded this, it was rated as "poor".

[0279] [Pattern rectangularity] A 250 nm line-and-space resist pattern formed by irradiating with the optimum exposure dose obtained in the sensitivity evaluation was observed using the scanning electron microscope, and the cross-sectional shape of the line-and-space pattern was evaluated. The rectangularity of the resist pattern was evaluated as "A" (very good) if the ratio of the length of the bottom side to the length of the top side in the cross-sectional shape was 1.00 or more and 1.10 or less, and as "B" (poor) if it exceeded 1.10.

[0280] [Storage Stability] The positive-working radiation-sensitive composition for KrF exposure was stored at 35° C. for 30 days, and then the optimum exposure dose for forming a 250 nm line and space pattern, i.e., the sensitivity S ３０ The sensitivity S before storage was measured. ０ The sensitivity fluctuation ratio after 30 days of storage was calculated based on the following formula: If the fluctuation ratio was 0% or more and 1.0% or less, it was evaluated as "A" (good), and if it was more than 1.0%, it was evaluated as "B" (bad). Sensitivity fluctuation ratio (%) = {|S ３０ -S ０ | / S ０} x 100

[0281] [Exposure latitude] In the range of exposure amount including the above sensitivity, the exposure amount is set to 1 mJ / cm ２Resist patterns were formed at different exposure doses, and the line widths of each were measured using the scanning electron microscope. From the relationship between the obtained line width and exposure dose, the exposure dose E(225) at which the line width was 225 nm and the exposure dose E(275) at which the line width was 275 nm were determined, and the exposure latitude (%) was calculated using the formula: exposure latitude = (E(225) - E(275)) x 100 / (optimum exposure dose). The larger the exposure latitude value, the smaller the fluctuation in the dimensions of the pattern obtained when the exposure dose fluctuates, and the higher the yield during device fabrication can be. When the exposure latitude value was compared to that of Comparative Example 1, an improvement of 10% or more (exposure latitude value of 110% or more) was evaluated as "A" (good), and an improvement of less than 10% (exposure latitude value less than 110%) was evaluated as "B" (poor). In the table, the "-" for Comparative Example 1 indicates that this is the standard for calculating the exposure latitude.

[0282] [Depth of Focus] The depth of focus (DOF) range in which the line and space pattern formed was 225 nm or more and 275 nm or less was measured for the resist pattern resolved at the optimum exposure dose obtained in the sensitivity evaluation above. The depth of focus was evaluated as "A" (good) when it was 150 nm or more, and as "B" (poor) when it was less than 150 nm.

[0283] [Number of Development Defects] A resist film was exposed to an optimum exposure dose to form a 250 nm line and space 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 50 μm or less were determined to be derived from the resist film, and the number of such defects was calculated. The number of development defects was evaluated as "good" when the number of defects determined to be derived from the resist film was 150 or less, and as "poor" when the number exceeded 150.

[0284]

[0285] As is clear from the results in Table 6, when the radiation-sensitive compositions of the Examples were used for KrF positive-tone exposure, they were good in sensitivity, pattern rectangularity, storage stability, exposure latitude, development defect performance, and depth of focus, whereas the Comparative Examples were inferior in each property to the Examples. Therefore, when the radiation-sensitive compositions of the Examples are used for KrF positive-tone exposure, resist patterns can be formed that have optimal sensitivity and good pattern rectangularity, storage stability, exposure latitude, development defect performance, and depth of focus.

[0286] [Preparation of Negative Radiation-Sensitive Composition for KrF Exposure] [Example 46] [A] 100 parts by mass of (A-1) as a polymer, [B] 5.0 parts by mass of (B-1) as a radiation-sensitive acid generator, [C] 0.05 parts by mass of (C-2) as an acid diffusion controller, [D] 15.0 parts by mass of (D-3) and 0.05 parts by mass of (D-6) as other additives, and [E] 400 parts by mass of a mixed solvent of (E-1) and (E-5) as a solvent were mixed and filtered through a membrane filter having a pore size of 0.2 μm, to prepare a radiation-sensitive composition (J-46).

[0287] Examples 47 to 86 and Comparative Examples 10 to 16 Radiation-sensitive compositions (J-47) to (J-86) and (CJ-10) to (CJ-16) were prepared in the same manner as in Example 46, except that the types and amounts of each component shown in Table 7 below were used.

[0288]

[0289] <Formation of Resist Pattern Using Negative Radiation-Sensitive Composition for KrF Exposure> The negative radiation-sensitive composition for KrF exposure prepared above was applied to a 12-inch silicon wafer that had been treated with hexamethyldisilazane using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT8"), and prebaked at 130°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 5 μm. Next, this resist film was exposed to light using a KrF excimer laser scanner (ASML's "PAS5500 / 850C wavelength 248 nm") through a mask pattern with 200 nm holes and a 500 nm pitch under optical conditions of NA = 0.68 and σ = 0.60. After exposure, the wafer was subjected to post-exposure bake (PEB) at 130°C for 60 seconds. Thereafter, the resist film was subjected to alkaline development using a 2.38% by mass aqueous solution of TMAH as an alkaline developer, and after development, the resist film was washed with water and further dried to form a negative resist pattern (200 nm holes, 500 nm pitch).

[0290] <Evaluation> The resist patterns formed using the above-described negative radiation-sensitive compositions for KrF exposure were evaluated for sensitivity, pattern circularity, storage stability, exposure latitude, and depth of focus according to the methods described below. A scanning electron microscope (CG-5000 manufactured by Hitachi High-Technologies Corporation) was used to measure the resist patterns. The results are shown in Table 8 below.

[0291] [Sensitivity] In forming a resist pattern using the negative radiation-sensitive composition for KrF exposure, the exposure dose for forming a contact hole pattern with 200 nm holes and a 500 nm pitch was defined as the optimum exposure dose, and this optimum exposure dose was used as the sensitivity (mJ / cm ２ The sensitivity was 50 mJ / cm ２ The following cases are considered "good" and 50mJ / cm ２ If it exceeded this, it was rated as "poor".

[0292] [Pattern circularity] The 200 nm holes and 500 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).

[0293] [Storage Stability] The negative radiation-sensitive composition for KrF exposure was stored at 35° C. for 30 days, and then the optimum exposure dose for forming a contact hole pattern with 200 nm holes and a 500 nm pitch, i.e., the sensitivity S ３０ The sensitivity S before storage was measured. ０ The sensitivity fluctuation ratio after 30 days of storage was calculated based on the following formula: If the fluctuation ratio was 0% or more and 1.0% or less, it was evaluated as "A" (good), and if it was more than 1.0%, it was evaluated as "B" (bad). Sensitivity fluctuation ratio (%) = {|S ３０ -S ０ | / S ０} x 100

[0294] [Exposure latitude] In the range of exposure amount including the above sensitivity, the exposure amount is set to 1 mJ / cm ２ Resist patterns were formed at different exposure doses, and the diameters of the holes were measured using the scanning electron microscope. From the relationship between the obtained diameter and exposure dose, the exposure dose E(180) at which the diameter became 180 nm and the exposure dose E(220) at which the diameter became 220 nm were determined, and the exposure latitude (%) was calculated using the formula: exposure latitude = (E(180) - E(220)) x 100 / (optimum exposure dose). The larger the exposure latitude value, the smaller the fluctuation in the dimensions of the pattern obtained when the exposure dose fluctuates, thereby increasing the yield during device fabrication. When the exposure latitude value was compared to that of Comparative Example 1, an improvement of 10% or more (exposure latitude value of 110% or more) was evaluated as "A" (good), and an improvement of less than 10% (exposure latitude value less than 110%) was evaluated as "B" (poor). In the table, the "-" for Comparative Example 1 indicates that this is the standard for calculating the exposure latitude.

[0295] [Depth of Focus] The depth of focus (DOF) range in which the hole pattern formed was 180 nm or more and 220 nm or less was measured for the resist pattern resolved at the optimum exposure dose obtained in the sensitivity evaluation above. The depth of focus was evaluated as "A" (good) when it was 150 nm or more, and as "B" (poor) when it was less than 150 nm.

[0296]

[0297] As is clear from the results in Table 8, when the radiation-sensitive compositions of the Examples were used for KrF negative exposure, they were excellent in sensitivity, pattern circularity, storage stability, exposure latitude, and depth of focus, whereas the Comparative Examples were inferior in each property to the Examples. Therefore, when the radiation-sensitive compositions of the Examples are used for KrF negative exposure, resist patterns with optimal sensitivity and excellent pattern circularity, storage stability, exposure latitude, and depth of focus can be formed.

[0298] [Preparation of Positive Radiation-Sensitive Composition for Extreme Ultraviolet (EUV) Exposure] [Example 87] [A] 100 parts by mass of (A-10) as a polymer, [B] 20.0 parts by mass of (B-1) as a radiation-sensitive acid generator, [C] 10.0 parts by mass of (C-10) as an acid diffusion controller, [F] 3.0 parts by mass (solids content) of (F-3) as a high fluorine content polymer, and [E] 6,110 parts by mass of a mixed solvent of (E-1) / (E-4) as a solvent were mixed and filtered through a membrane filter having a pore size of 0.2 μm, to prepare a radiation-sensitive composition (J-87).

[0299] Examples 88 to 104 and Comparative Examples 17 to 20 Radiation-sensitive compositions (J-88) to (J-104) and (CJ-17) to (CJ-20) were prepared in the same manner as in Example 87, except that the types and amounts of each component shown in Table 9 below were used.

[0300]

[0301] <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 50 nm. Next, this resist film was exposed using an EUV exposure apparatus (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 (20 nm line and space pattern).

[0302] <Evaluation> The resist patterns formed using the above-described positive-working radiation-sensitive composition for EUV exposure were evaluated for sensitivity, LWR, pattern rectangularity, and storage stability according to the methods described below. The results are shown in Table 10. The resist patterns were measured using a scanning electron microscope (CG-5000 manufactured by Hitachi High-Technologies Corporation).

[0303] [Sensitivity] In forming a resist pattern using the positive-working radiation-sensitive composition for EUV exposure, the exposure dose required to form a 20 nm line and space pattern was defined as the optimum exposure dose, and this optimum exposure dose was used as the sensitivity (mJ / cm ２ The sensitivity was 35 mJ / cm ２ The following cases are considered "good" and 35 mJ / cm ２ If it exceeded this, it was rated as "poor".

[0304] [LWR] A resist pattern was formed by irradiating the resist with the optimal exposure dose determined in the sensitivity evaluation above, and adjusting the mask size to form a 20 nm line-and-space pattern. The formed resist pattern was observed from above the pattern using the scanning electron microscope described above. The line width variation was measured at a total of 500 points, and a 3 sigma value was calculated from the distribution of the measured values, and this 3 sigma value was taken as the LWR (nm). The smaller the LWR value, the smaller the line chatter and the better the result. LWR was evaluated as "good" when it was 2.5 nm or less, and as "poor" when it exceeded 2.5 nm.

[0305] [Pattern rectangularity] A 20 nm line-and-space resist pattern formed by irradiating with the optimum exposure dose obtained in the sensitivity evaluation was observed using the scanning electron microscope, and the cross-sectional shape of the line-and-space pattern was evaluated. The rectangularity of the resist pattern was evaluated as "A" (good) if the ratio of the length of the bottom side to the length of the top side in the cross-sectional shape was 1.00 or more and 1.10 or less, and as "B" (poor) if it exceeded 1.10.

[0306] [Storage Stability] The positive-working radiation-sensitive composition for EUV exposure was stored at 35° C. for 30 days, and then the optimum exposure dose for forming a 20 nm line and space pattern, i.e., the sensitivity S ３０ The sensitivity S before storage was measured. ０ The sensitivity fluctuation ratio after 30 days of storage was calculated based on the following formula: If the fluctuation ratio was 0% or more and 1.0% or less, it was evaluated as "A" (good), and if it was more than 1.0%, it was evaluated as "B" (bad). Sensitivity fluctuation ratio (%) = {|S ３０ -S ０ | / S ０} x 100

[0307]

[0308] As is clear from the results in Table 10, when the radiation-sensitive compositions of the Examples were used for EUV exposure, the sensitivity, LWR, pattern rectangularity, and storage stability were good, whereas the Comparative Examples were inferior to the Examples in each of the properties.

[0309] [Preparation of positive-tone radiation-sensitive composition for ArF immersion exposure] [Example 105] 100 parts by mass of [A] polymer (A-14), 10.0 parts by mass of [B] radiation-sensitive acid generator (B-1), 4.0 parts by mass of [C] acid diffusion controller (C-1), 5.0 parts by mass (solids content) of [F] high-fluorine polymer (F-1), and 3,400 parts by mass of a mixed solvent of (E-1) / (E-2) / (E-3) as a solvent were mixed and filtered through a membrane filter having a pore size of 0.2 μm, to prepare a radiation-sensitive composition (J-105).

[0310] [Examples 106 to 116, 127 to 129 and Comparative Examples 21 to 24] Radiation-sensitive compositions (J-106) to (J-116), (J-127) to (J-129), and (CJ-21) to (CJ-24) were prepared in the same manner as in Example 105, except that the types and amounts of each component shown in Table 11 below were used.

[0311]

[0312] <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 having an average thickness of 100 nm. The positive radiation-sensitive composition for ArF immersion 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 having an average thickness of 90 nm. Next, this resist film was exposed to light through a 70 nm line and space mask pattern 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). After exposure, a PEB (post-exposure bake) 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 (70 nm line and space pattern).

[0313] <Evaluation> The resist patterns formed using the above-described positive-working radiation-sensitive composition for ArF immersion exposure were evaluated for sensitivity, LWR, pattern rectangularity, and storage stability according to the methods described below. The results are shown in Table 12. The resist patterns were measured using a scanning electron microscope (CG-5000 manufactured by Hitachi High-Technologies Corporation).

[0314] [Sensitivity] In forming a resist pattern using the positive radiation-sensitive composition for ArF immersion exposure, the exposure dose required to form a 70 nm line and space pattern was defined as the optimum exposure dose, and this optimum exposure dose was defined as the sensitivity (mJ / cm ２ The sensitivity was 35 mJ / cm ２ The following cases are considered "good" and 35 mJ / cm ２ If it exceeded this, it was rated as "poor".

[0315] [LWR] A 70 nm line-and-space resist pattern was formed by irradiating the resist with 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 line width variation was measured at a total of 500 points, and a 3 sigma value was calculated from the distribution of the measured values, and this 3 sigma value was taken as the LWR (nm). The smaller the LWR value, the smaller the line roughness and the better the result. LWR was evaluated as "good" when it was 3.0 nm or less, and as "poor" when it exceeded 3.0 nm.

[0316] [Pattern rectangularity] A 70 nm line-and-space resist pattern formed by irradiating with the optimum exposure dose obtained in the sensitivity evaluation was observed using the scanning electron microscope, and the cross-sectional shape of the line-and-space pattern was evaluated. The rectangularity of the resist pattern was evaluated as "A" (good) if the ratio of the length of the bottom side to the length of the top side in the cross-sectional shape was 1.00 or more and 1.10 or less, and as "B" (poor) if it exceeded 1.10.

[0317] [Storage Stability] The positive radiation-sensitive composition for ArF immersion exposure was stored at 35° C. for 30 days, and then the optimum exposure dose for forming a 70 nm line and space pattern, i.e., the sensitivity S ３０ The sensitivity S before storage was measured. ０ The sensitivity fluctuation ratio after 30 days of storage was calculated based on the following formula: If the fluctuation ratio was 0% or more and 1.0% or less, it was evaluated as "A" (good), and if it was more than 1.0%, it was evaluated as "B" (bad). Sensitivity fluctuation ratio (%) = {|S ３０ -S ０ | / S ０} x 100

[0318]

[0319] As is clear from the results in Table 12, when the radiation-sensitive compositions of the Examples were used in ArF immersion exposure, they exhibited good sensitivity, LWR, pattern rectangularity, and storage stability, whereas the Comparative Examples were inferior in each property to the Examples. Therefore, when the radiation-sensitive compositions of the Examples were used in ArF immersion exposure, resist patterns with optimal sensitivity, good LWR, pattern rectangularity, and storage stability could be formed.

[0320] [Preparation of Negative Radiation-Sensitive Composition for ArF Exposure, and Formation and Evaluation of Resist Pattern Using This Composition] [Example 117] 100 parts by mass of [A] polymer (A-14), 12.0 parts by mass of [B] radiation-sensitive acid generator (B-1), 10.0 parts by mass of [D] acid diffusion controller (D-1), 2.0 parts by mass (solids content) of [F] high-fluorine-content polymer (F-2), and 3,230 parts by mass (2,240 parts by mass / 960 parts by mass / 200 parts by mass) of a mixed solvent of (E-1) / (E-2) / (E-3) as a 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-117).

[0321] 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 having an average thickness of 100 nm. The negative radiation-sensitive composition for ArF exposure (J-117) 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 having an average thickness of 90 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 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 developed using n-butyl acetate as an organic solvent developer, and dried to form a negative resist pattern (a contact hole pattern with 50 nm holes and a 100 nm pitch).

[0322] The resist patterns prepared using the negative-working radiation-sensitive composition for ArF exposure were evaluated for sensitivity in the same manner as in the evaluation of the resist patterns prepared using the positive-working radiation-sensitive composition for ArF exposure. The CDU performance, pattern circularity, storage stability, and depth of focus were also evaluated according to the following methods.

[0323] [CDU] 50 nm holes and 100 nm pitch contact holes were formed by irradiating the resist with 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 variation in the contact holes was measured at a total of 500 points, and a 3 sigma value was calculated from the distribution of the measured values, and this 3 sigma value was taken as CDU (nm). The smaller the CDU value, the smaller the hole roughness and the better it was. CDU performance was evaluated as "good" when it was less than 3.5 nm, and as "poor" when it was 3.5 nm or more.

[0324] [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, and their vertical and horizontal sizes were measured. A ratio of vertical size to horizontal size of 0.95 or more and less than 1.05 was evaluated as "A" (very good), a ratio of 0.90 or more and less than 0.95, or 1.05 or more and less than 1.10 was evaluated as "B" (good), and a ratio of less than 0.90 or 1.10 or more was evaluated as "C" (poor).

[0325] [Storage Stability] The negative radiation-sensitive composition for ArF exposure was stored at 35° C. for 30 days, and then the optimum exposure dose for forming a contact hole pattern with 50 nm holes and a 100 nm pitch, i.e., the sensitivity S ３０ The sensitivity S before storage was measured. ０ The sensitivity fluctuation ratio after 30 days of storage was calculated based on the following formula: If the fluctuation ratio was 0% or more and 1.0% or less, it was evaluated as "A" (very good), if it was more than 1.0% and 2.0% or less, it was evaluated as "B" (good), and if it was more than 2.0%, it was evaluated as "C" (poor). Sensitivity fluctuation ratio (%) = {|S ３０ -S ０ | / S ０} x 100

[0326] [Depth of Focus] The depth of focus (DOF) range in which the diameter of the hole pattern formed was 40 nm to 60 nm in the resist pattern resolved at the optimum exposure dose determined in the sensitivity evaluation was measured. A depth of focus of 100 nm or more was evaluated as "good," and a depth of focus of less than 100 nm was evaluated as "poor."

[0327] As a result, the radiation-sensitive composition of Example 117 exhibited excellent sensitivity, CDU, pattern circularity, storage stability and depth of focus even when a negative resist pattern was formed by ArF exposure.

[0328] [Preparation of Negative Radiation-Sensitive Composition for EUV Exposure, and Formation and Evaluation of Resist Pattern Using This Composition] [Example 118] 100 parts by mass of [A] (A-10) as a polymer, [B] 30.0 parts by mass of (B-13) as a radiation-sensitive acid generator, [C] 10.0 parts by mass of (C-10) as an acid diffusion controller, [F] 5.0 parts by mass (solids content) of (F-3) as a high fluorine content polymer, and [E] 6,110 parts by mass (4280 parts by mass / 1830 parts by mass) of a mixed solvent of (E-1) / (E-4) as a solvent were mixed and filtered through a membrane filter having a pore size of 0.2 μm, to prepare a radiation-sensitive composition (J-118).

[0329] 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-118) 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 40 nm pitch).

[0330] The resist pattern formed using the negative radiation-sensitive composition for EUV exposure was evaluated in the same manner as the evaluation of the resist pattern formed using the negative radiation-sensitive composition for ArF exposure. As a result, the radiation-sensitive composition of Example 118 was found to have good sensitivity, CDU performance, pattern circularity, storage stability, and depth of focus, even when a negative resist pattern was formed by EUV exposure.

[0331] The radiation-sensitive composition, pattern forming method, and onium salt compound described above can form a resist pattern that has good storage stability, good sensitivity to exposure light, and excellent pattern rectangularity, pattern circularity, exposure latitude, depth of focus, development defect suppression, LWR, and CDU. Therefore, these can be suitably used in the processing of semiconductor devices, which are expected to become increasingly miniaturized in the future.

Claims

1. A radiation-sensitive composition comprising an onium salt compound represented by the following formula (1), a polymer, and a solvent: (In formula (1), R ｆ is a halogen atom or a cyano group. n is an integer of 0 to 4. When n is 2 or more, multiple R ｆ are the same or different. １ is R １ and the carbon atom to which ＊ -COO-, ＊ -OCO-, ＊ -SO ２ --, ＊ -S-, ＊ -CO-, ＊ -O-CO-O-, ＊ -CONR'- or ＊ It is a monovalent organic group having 1 to 20 carbon atoms, a hydrogen atom, a halogen atom, a cyano group or a fluorinated alkyl group bonded via --NR'CO--. Each R' is independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. ＊ is R １ is a bond to the carbon atom to which n is bonded. However, when n is 0, R １ is a halogen atom or a cyano group. ２ is a hydroxy group, a nitro group, an amino group, a carboxy group, or a monovalent organic group having 1 to 20 carbon atoms. m is an integer of 0 to 4. When m is 2 or more, multiple R ２ are the same or different. n+m is an integer of 0 to 4. Ar is a monovalent organic group having an aromatic ring with 5 to 40 ring members. X is a methylene group, -O-, -CO- or -SO ２ However, when X is a methylene group, the aromatic ring of Ar and S in the formula ＋ and are directly bonded, and R １ does not contain a polymerizable group. ４１ , R ４２ , R ４３ , R ４４ , R ４５ and R ４８ R are each independently a hydrogen atom, a hydroxyl group, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms. ４６ and R ４７ are each independently a hydrogen atom, a hydroxyl group, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms, or R ４６ and R ４７ represent a ring structure having 3 to 10 ring members formed by combining with each other and the two carbon atoms to which they are attached.

2. The radiation-sensitive composition according to claim 1, wherein the aromatic ring is a benzene ring or a naphthalene ring.

3. The radiation-sensitive composition according to claim 1, wherein X is a methylene group or --O--.

4. R ４１ , R ４２ , R ４３ , R ４４ , R ４５ , R ４６ , R ４７ and R ４８ The radiation-sensitive composition according to claim 1 , wherein is a hydrogen atom.

5. The radiation-sensitive composition according to claim 1, wherein n is an integer of 1 to 4.

6. R １ is R １ and the carbon atom to which ＊ -COO-, ＊ -OCO-, ＊ -SO ２ -or- ＊ 6. The radiation-sensitive composition according to claim 1, wherein the alkyl group is a monovalent organic group having 1 to 20 carbon atoms, a halogen atom, a cyano group, or a fluorinated alkyl group bonded via --CO--.

7. The radiation-sensitive composition according to any one of claims 1 to 5, wherein the content of the onium salt compound is 0.1 parts by mass or more and 50 parts by mass or less based on 100 parts by mass of the polymer.

8. The radiation-sensitive composition according to any one of claims 1 to 5, wherein the polymer contains a structural unit having an acid-dissociable group, and the structural unit is represented by the following formula (A1): (In the above formula (A1), R α R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ａ１ R is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. Ａ２ and R Ａ３ each independently represents a monovalent linear hydrocarbon group having 1 to 20 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or R Ａ２ and R Ａ３ are combined together with the carbon atom to which they are bonded to form a divalent alicyclic group having 3 to 20 carbon atoms. m11 and m12 are each independently 0 or 1. However, when m11 is 1, m12 is 1. When m11 is 0, L Ａ１ represents a single bond or a divalent linking group; when m11 is 1, L Ａ１ is a divalent linking group.

9. The radiation-sensitive composition according to any one of claims 1 to 5, wherein the polymer further contains a structural unit having a phenolic hydroxyl group.

10. The radiation-sensitive composition according to any one of claims 1 to 5, further comprising an acid diffusion controller.

11. A pattern forming method comprising the steps of: applying the radiation-sensitive composition according to any one of claims 1 to 5 directly or indirectly to a substrate to form a resist film; exposing the resist film to light; and developing the exposed resist film.

12. The pattern forming method according to claim 11, wherein the exposure is carried out with g-line, i-line, KrF excimer laser, ArF excimer laser or extreme ultraviolet ray.

13. An onium salt compound represented by the following formula (1): (In formula (1), R ｆ is a halogen atom or a cyano group. n is an integer of 0 to 4. When n is 2 or more, multiple R ｆ are the same or different. １ is R １ and the carbon atom to which ＊ -COO-, ＊ -OCO-, ＊ -SO ２ --, ＊ -S-, ＊ -CO-, ＊ -O-CO-O-, ＊ -CONR'- or ＊ It is a monovalent organic group having 1 to 20 carbon atoms, a hydrogen atom, a halogen atom, a cyano group or a fluorinated alkyl group bonded via --NR'CO--. Each R' is independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. ＊ is R １ is a bond to the carbon atom to which n is bonded. However, when n is 0, R １ is a halogen atom or a cyano group. ２ is a hydroxy group, a nitro group, an amino group, a carboxy group, or a monovalent organic group having 1 to 20 carbon atoms. m is an integer of 0 to 4. When m is 2 or more, multiple R ２ are the same or different. n+m is an integer of 0 to 4. Ar is a monovalent organic group having an aromatic ring with 5 to 40 ring members. X is a methylene group, -O-, -CO- or -SO ２ However, when X is a methylene group, the aromatic ring of Ar and S in the formula ＋ and are directly bonded, and R １ does not contain a polymerizable group. ４１ , R ４２ , R ４３ , R ４４ , R ４５ and R ４８ R are each independently a hydrogen atom, a hydroxyl group, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms. ４６ and R ４７ are each independently a hydrogen atom, a hydroxyl group, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms, or R ４６ and R ４７ represent a ring structure having 3 to 10 ring members formed by combining with each other and the two carbon atoms to which they are attached.

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