Method or forming resist pattern and radiation-sensitive resin composition

Abstract

To provide a method or forming a resist pattern and a radiation-sensitive resin composition which have excellent performance in sensibility, resolution or the like in an exposure process when a next generation exposure technique is applied.SOLUTION: A method or forming a resist pattern includes: (1) a step of forming a resist film having a content of (C) a radiation-sensitive acid generator of 0.1 mass% or less; (2) a step of exposing the resist film by EUV or electron beam (EB); and (3) a step of developing the resist film exposed in the step (2). In the step (1), the resist film is formed of (A) a radiation-sensitive resin composition, the radiation-sensitive resin composition contains a resin having a structural unit (a2) which includes a group dissociating by EUV or electron beam (EB) exposure in the absence of (A1) radiation-sensitive acid generator, the structural unit (a2) has a tertiary alkyl ester portion, and the structural unit (a2) is expressed by a specific structure.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for forming a resist pattern and a radiation-sensitive resin composition that can be used for the method. [Background technology]

[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 resin in an alkaline or organic developer between the exposed and unexposed areas, thereby forming a resist pattern on a substrate.

[0003] The photolithography technology described above uses short-wavelength radiation such as ArF excimer lasers, or combines this radiation with liquid immersion lithography to promote pattern miniaturization. Next-generation technologies are being developed that utilize even shorter-wavelength radiation such as electron beams, X-rays, and extreme ultraviolet (EUV), and resist materials containing styrene-based resins with improved radiation absorption efficiency are also being investigated (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-52294 Summary of the Invention [Problem to be solved by the invention]

[0005] The above-mentioned next-generation technologies also require resist performance equal to or better than conventional ones in terms of sensitivity, resolution, etc. However, existing radiation-sensitive resin compositions do not provide these properties at a sufficient level.

[0006] An object of the present invention is to provide a radiation-sensitive resin composition and a method for forming a resist pattern that are capable of exhibiting sufficient levels of sensitivity and resolution when next-generation technology is applied. [Means for solving the problem]

[0007] 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.

[0008] That is, in one embodiment, the present invention provides: (C) Step (1) of forming a resist film containing a radiation-sensitive acid generator in an amount of 0.1% by mass or less; (2) exposing the resist film to EUV or electron beam (EB); and The present invention relates to a method for forming a resist pattern, which comprises a step (3) of developing the resist film exposed in the step (2).

[0009] The method for forming a resist pattern of the present invention includes step (1) of forming a resist film having a content of (C) radiation-sensitive acid generator of 0.1 mass % or less, thereby enabling the resist film to exhibit excellent levels of sensitivity, resolution, etc. in the exposure step. Although the scope of the present invention is not necessarily limited by this speculation, it is speculated that the mechanism of action for the manifestation of the above-mentioned effects is that by setting the content of (C) radiation-sensitive acid generator in the resist film to 0.1 mass % or less, the constituent components of the resist film are simplified, thereby improving uniformity, and adverse effects at the interface between exposed and unexposed areas due to acid generated during the exposure step are suppressed, resulting in improved resist performance.

[0010] In one embodiment, the method for forming a resist pattern of the present invention comprises: In the above step (1), the resist film is formed from (A) a radiation-sensitive resin composition, and the radiation-sensitive resin composition preferably contains (A1) a resin whose solubility changes upon exposure to EUV or electron beam (EB) in the absence of a radiation-sensitive acid generator. By having the above-described configuration, the resist film can function as a resist film in a conventional exposure step or the like even without substantially containing a radiation-sensitive acid generator (C), which is conventional, and as a result, various resist properties can be more reliably improved.

[0011] In one embodiment, the method for forming a resist pattern of the present invention comprises: In the above step (1), the resist film is preferably formed from (A) the radiation-sensitive resin composition, and the content of (C) the radiation-sensitive acid generator in the (A) radiation-sensitive resin composition is preferably 0.1 mass % or less relative to the total of all components other than (B) the solvent. This configuration makes it possible to more easily form a resist film that is substantially free of (C) the radiation-sensitive acid generator, and more reliably improves various resist performances.

[0012] In one embodiment, the method for forming a resist pattern of the present invention comprises: In the above step (1), the resist film is preferably formed from (A) a radiation-sensitive resin composition, and the (A) radiation-sensitive resin composition preferably does not contain a radiation-sensitive acid generator. By having the above configuration, a resist film that is substantially free of (C) a radiation-sensitive acid generator can be more easily formed, and various resist properties can be more reliably improved.

[0013] In one embodiment, the method for forming a resist pattern of the present invention comprises: The resin (A1) whose solubility changes is preferably a resin that changes to be water-soluble or alkali-soluble. By having the above-mentioned constitution, various resist properties can be improved more reliably.

[0014] On the other hand, the present invention provides, as another embodiment, The present invention relates to a radiation-sensitive resin composition comprising: (A2) a resin containing a group that dissociates upon exposure to EUV or an electron beam (EB); (B) a solvent; and (C) a radiation-sensitive acid generator, wherein the amount of the radiation-sensitive acid generator (C) in the radiation-sensitive resin composition is 0.1 mass % or less based on the total mass of components other than the solvent (B).

[0015] The radiation-sensitive resin composition of the present invention contains (A2) a resin containing a group that dissociates upon exposure to EUV or an electron beam (EB), and the radiation-sensitive resin composition contains the radiation-sensitive acid generator (C) in an amount of 0.1 mass% or less relative to the total of all components other than the solvent (B), thereby enabling the composition to exhibit excellent levels of sensitivity, resolution, etc. in the exposure step. While the scope of the present invention is not necessarily limited by this speculation, it is speculated that the mechanism of action for the manifestation of the above effects is that by limiting the content of the radiation-sensitive acid generator (C) in the radiation-sensitive resin composition to 0.1 mass% or less relative to the total of all components other than the solvent (B), the components constituting the resist film are simplified, thereby improving uniformity, and adverse effects at the interface between exposed and unexposed areas due to acid generated during the exposure step are suppressed, resulting in improved resist performance.

[0016] In one embodiment, the radiation-sensitive resin composition of the present invention comprises: It is preferable that the resist composition is composed of only (A2) a resin containing a group that dissociates upon exposure to EUV or an electron beam (EB), and (B) a solvent. By having the above-mentioned composition, the resist composition can function as a resist film in a conventional exposure step or the like even without substantially containing (C) a radiation-sensitive acid generator, which is conventional, and as a result, various resist properties can be more reliably improved.

[0017] In one embodiment, the radiation-sensitive resin composition of the present invention comprises: The resin containing the dissociating group (A2) is preferably a resin containing a group that dissociates to generate a carboxylic acid structure. By having the above-mentioned structure, the resin can function as a resist film in a conventional exposure step or the like even without substantially containing a conventional radiation-sensitive acid generator (C), and as a result, various resist properties can be more reliably improved. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments.

[0019] <(A) Radiation-sensitive resin composition> The radiation-sensitive resin composition (A) according to this embodiment (hereinafter also simply referred to as the "composition") contains a specific resin (A0) and a solvent (B). The composition may contain other optional components as long as the effects of the present invention are not impaired.

[0020] (Resin (A0)) The resin (A0) in the present invention is a resin that can be used to form a resist film in the exposure step and development step, even if it does not substantially contain a radiation-sensitive acid generator, because its solubility in a developer changes upon exposure to EUV or electron beam (EB). By using the resin (A0), the resist film can be used in the exposure step and development step without substantially relying on the acid generated by a radiation-sensitive acid generator upon exposure, as in the conventional case. Furthermore, the simplified components of the resist film can improve uniformity and suppress adverse effects at the interface between exposed and unexposed areas due to the acid generated during the exposure step, resulting in improved resist performance.

[0021] In the present invention, examples of the resin (A0) include (A1) a resin whose solubility changes upon exposure to EUV or electron beam (EB) in the absence of a radiation-sensitive acid generator.

[0022] In the present invention, the resin (A1) whose solubility changes upon exposure to EUV or electron beam (EB) in the absence of a radiation-sensitive acid generator refers to a resin whose solubility in a developer changes upon exposure to EUV or electron beam (EB) without substantially depending on the acid generated by a conventional radiation-sensitive acid generator upon exposure. The term "change in solubility" as used herein refers to a resin whose solubility in a developer increases or decreases.

[0023] Examples of the (A1) resin whose solubility changes include a resin that changes to become water-soluble or alkali-soluble. Examples of the resin that changes to become water-soluble or alkali-soluble include a resin that regenerates or generates, for example, a hydroxyl group, a carboxyl group, an amino group, an ionic group, or a sulfo group in the resin structure upon exposure to light.

[0024] In the present invention, examples of the resin (A0) include (A2) a resin containing a group that dissociates upon exposure to EUV or electron beam (EB).

[0025] In the present invention, the resin (A2) containing a group that dissociates upon exposure to EUV or an electron beam (EB) refers to a resin that contains a group that dissociates in the resin structure by an elimination reaction or the like upon exposure to EUV or an electron beam (EB), without substantially relying on an acid generated by exposure from a conventional radiation-sensitive acid generator. The "dissociable group" may be, for example, a group that can generate a hydroxyl group, a carboxyl group, an amino group, an ionic group, a sulfo group, or the like upon dissociation upon exposure.

[0026] Furthermore, (A2) resins containing a group that dissociates upon exposure to EUV or electron beam (EB) include, for example, resins containing a group that dissociates to generate a carboxylic acid structure, and resins containing a group that dissociates to generate a hydroxyl group structure. The carboxylic acid structure that dissociates includes, for example, a carboxyl group (-COOH) or a salt thereof (carboxylate group, -COOH). -The hydroxyl group structure generated by dissociation includes an alcoholic hydroxyl group, a phenolic hydroxyl group (-OH) and its salt (-O - ) etc. can be mentioned.

[0027] The resin (A2) containing a dissociating group may, for example, contain a structural unit having a group that dissociates to form a carboxylic acid structure, or a structural unit having a group that dissociates to form a hydroxyl group structure. Preferred examples include a resin containing a structural unit having a group that dissociates to form a carboxylic acid structure, a structural unit having a phenolic hydroxyl group, and at least one structural unit selected from structural units having a polar group.

[0028] Further, preferred examples of the structural unit having a polar group include those containing at least one selected from the group consisting of a structural unit having an alcoholic hydroxyl group, a structural unit having a lactone structure, a structural unit having a cyclic carbonate structure, and a structural unit having a sultone structure.

[0029] In the present invention, the resin (A0) may also be an aggregate of polymers having a structural unit (a1) containing a phenolic hydroxyl group and a structural unit (a2) containing a group that dissociates upon exposure to EUV or electron beam (EB) in the absence of a radiation-sensitive acid generator (hereinafter, this resin may also be referred to as a "base resin").

[0030] The base resin (A0) may contain structural units other than the structural units (a1) and (a2). Each structural unit will be described below.

[0031] [Structural unit (a1)] The structural unit (a1) is a structural unit containing a phenolic hydroxyl group. By including the structural unit (a1) and, if necessary, other structural units, the resin (A0) can more appropriately adjust its solubility in a developer, thereby further improving the sensitivity, resolution, and other resist performance of the radiation-sensitive resin composition. Furthermore, when EUV, electron beams, or the like are used as the radiation irradiated in the exposure step of the resist pattern formation method, the structural unit (a1) in the resin (A0) contributes to improving etching resistance and the difference in developer solubility (dissolution contrast) between exposed and unexposed areas. This is particularly suitable for pattern formation using exposure to radiation with a wavelength of 50 nm or less, such as electron beams or EUV.

[0032] Examples of the structural unit (a1) include structural units represented by the following formula (af):

[0033] [ka]

[0034] In the above formula (af), R AF1 is a hydrogen atom or a methyl group. AF is a single bond, -COO-, -O- or -CONH-. AF2 is a monovalent organic group having 1 to 20 carbon atoms. f1 is an integer from 0 to 3. f1 If is 2 or 3, multiple R AF2 may be the same or different. f2 is an integer between 1 and 3, where n f1 +n f2 is less than or equal to 5. af is an integer between 0 and 2.

[0035] L AF is preferably a single bond or —COO—.

[0036] From the viewpoint of copolymerizability of the monomer that gives the structural unit (a1), L AFWhen is a single bond, the above R AF1 is preferably a hydrogen atom. AF If -COO-, then the above R AF1 is preferably a methyl group.

[0037] The organic group in the resin (A0) refers to a group containing at least one carbon atom.

[0038] Above R AF2 Examples of the monovalent organic group having 1 to 20 carbon atoms represented by the formula (I) include a monovalent hydrocarbon group having 1 to 20 carbon atoms, a group containing a divalent heteroatom-containing group between carbon atoms of the hydrocarbon group or at the terminal on the bond side, and a group in which some or all of the hydrogen atoms in the group or the hydrocarbon group have been substituted with a monovalent heteroatom-containing group.

[0039] Above R AF2 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula: Alkyl groups such as methyl, ethyl, propyl, and butyl groups; alkenyl groups such as ethenyl, propenyl, and butenyl; chain hydrocarbon groups such as alkynyl groups such as ethynyl, propynyl, and butynyl; cycloalkyl groups such as a cyclopropyl group, a cyclopentyl group, a cyclohexyl group, a cyclooctyl group, a norbornyl group, and an adamantyl group; alicyclic hydrocarbon groups such as cycloalkenyl groups such as cyclopropenyl, cyclopentenyl, cyclohexenyl, and norbornenyl; aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group; Examples include aromatic hydrocarbon groups such as aralkyl groups such as benzyl, phenethyl, and naphthylmethyl groups.

[0040] Above R AF2As the alkyl group, a chain hydrocarbon group or a cycloalkyl group is preferable, an alkyl group or a cycloalkyl group is more preferable, and a methyl group, an ethyl group, a propyl group, a cyclopentyl group, a cyclohexyl group, a cyclooctyl group, and an adamantyl group are further preferable.

[0041] Examples of the divalent heteroatom-containing group include -O-, -CO-, -CO-O-, -S-, -CS-, -SO2-, -NR'-, and groups combining two or more of these, where R' is a hydrogen atom or a monovalent hydrocarbon group.

[0042] Examples of the monovalent heteroatom-containing group include halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom, hydroxy group, carboxy group, cyano group, amino group and sulfanyl group (-SH).

[0043] Of these, a monovalent chain hydrocarbon group is preferred, an alkyl group is more preferred, and a methyl group is even more preferred.

[0044] Above n f1 is preferably an integer of 0 to 2, more preferably 0 or 1, and even more preferably 0.

[0045] Above n f2 As the group, 1 and 2 are preferred, and 1 is more preferred.

[0046] Above n af As the number, 0 and 1 are preferred, and 0 is more preferred.

[0047] In the radiation-sensitive resin composition of the present invention, the structural unit (a1) may be a structural unit derived from hydroxystyrene.

[0048] The structural unit (a1) is preferably a structural unit represented by any of the following formulae (a1-1) to (a1-6).

[0049] [ka]

[0050] In the above formulas (a1-1) to (a1-6), R AF1 is the same as the above formula (af).

[0051] Of these, the structural units (a1-1) and (a1-2) are preferred, with (a1-1) being more preferred.

[0052] With respect to the structural unit (a1) in the resin (A0), the lower limit of the content of the structural unit (a1) relative to all structural units constituting the resin (A0) is preferably 10 mol%, more preferably 15 mol%, even more preferably 20 mol%, and particularly preferably 25 mol%. The upper limit of this content is preferably 90 mol%, more preferably 80 mol%, even more preferably 70 mol%, and particularly preferably 60 mol%. By ensuring that the content of the structural unit (a1) falls within the above range, the radiation-sensitive resin composition can further improve various resist properties such as sensitivity and resolution.

[0053] When attempting to directly radically polymerize a monomer having a phenolic hydroxyl group, such as hydroxystyrene, polymerization may be inhibited by the influence of the phenolic hydroxyl group. In this case, the phenolic hydroxyl group can be protected by a protecting group such as an alkali-labile group and then polymerized in that state, followed by hydrolysis to remove the protection group, thereby obtaining the structural unit (a1). The structural unit that gives the structural unit (a1) upon hydrolysis is preferably represented by the following formula (1):

[0054] [ka]

[0055] In the above formula (1), R 11 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 12 R is a monovalent hydrocarbon group or alkoxy group having 1 to 20 carbon atoms. 12Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include monovalent hydrocarbon groups having 1 to 20 carbon atoms. Examples of the alkoxy group include a methoxy group, an ethoxy group, and a tert-butoxy group.

[0056] Above R 12 As the alkyl group, an alkyl group and an alkoxy group are preferred, and among these, a methyl group and a tert-butoxy group are more preferred.

[0057] [Structural unit (a2)] The structural unit (a2) is, for example, a group whose solubility changes upon exposure to EUV or an electron beam (EB) in the absence of a radiation-sensitive acid generator, or a group that dissociates upon exposure to EUV or an electron beam (EB) in the absence of a radiation-sensitive acid generator.

[0058] In the present invention, the phrase "in the absence of a radiation-sensitive acid generator" refers to a situation in which a radiation-sensitive acid generator is not present or is substantially not present. Examples of the structural unit (a2) 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 resin composition, a structural unit represented by the following formula (2) (hereinafter also referred to as "structural unit (a2-1)") is preferred.

[0059] The structural units exemplified in the preceding paragraph are structures known in the art as acid-dissociable groups. In the present invention, the term "acid-dissociable group" refers to a group that substitutes a hydrogen atom in a carboxy group, a phenolic hydroxyl group, an alcoholic hydroxyl group, a sulfo group, or the like, and that has the property of dissociating under the action of an acid. As described above, the present invention does not require that the structural unit (a2) undergo dissociation such as elimination or a change in solubility due to the presence of an acid during the exposure step or the acid generated from the radiation-sensitive acid generator upon exposure. The radiation-sensitive resin composition has excellent pattern formability due to the resin containing the structural unit (a2).

[0060] [ka]

[0061] In the above formula (2), R 7 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 8 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. 9 and R 10 each independently represents a monovalent chain hydrocarbon group having 1 to 20 carbon atoms and substituted or unsubstituted with a fluorine atom, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms and substituted or unsubstituted with a fluorine atom, or a monovalent aromatic hydrocarbon group having 5 to 20 carbon atoms, or a divalent alicyclic group having 3 to 20 carbon atoms and substituted or unsubstituted with a fluorine atom, which is formed by combining these groups together with the carbon atoms to which they are bonded. 8 ~R 10 and / or, when the alicyclic group is present, the alicyclic group may have an unsaturated bond. 8 ~R 10 This also includes cases where two or more of the above together form one alicyclic structure.

[0062] Above R 7 From the viewpoint of copolymerizability of the monomer that gives the structural unit (a2-1), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred.

[0063] Above R 8 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 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0064] Above R 9 and R 10 Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) 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.

[0065] Above R 9 and R 10 Examples 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. Preferred monocyclic saturated hydrocarbon groups are cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. Preferred polycyclic cycloalkyl groups are bridged alicyclic hydrocarbon groups such as norbornyl, adamantyl, tricyclodecyl, and tetracyclododecyl groups. The bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two non-adjacent carbon atoms constituting the alicyclic ring are bonded together by a bonding chain containing one or more carbon atoms.

[0066] Above R 9 and R 10 Examples of the monovalent aromatic hydrocarbon group having 5 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.

[0067] Above R 8 As the alkyl group, a linear or branched saturated hydrocarbon group having 1 to 10 carbon atoms, or an alicyclic hydrocarbon group having 3 to 20 carbon atoms is preferred.

[0068] Also, R 8 ~R 10 and / or, when the above alicyclic group is present, the alicyclic group may have an unsaturated bond.

[0069] Also, R 8 ~R 10 This also includes cases where two or more of the above together form one alicyclic structure.

[0070] Above R 8 ~R 10When a plurality of the above are combined with each other to form at least one cyclic structure, the divalent alicyclic group having 3 to 20 carbon atoms formed by combining chain hydrocarbon groups or alicyclic hydrocarbon groups with each other and the carbon atoms to which they are bonded is not particularly limited as long as it is a group formed by removing two hydrogen atoms from the same carbon atom constituting a carbon ring of a monocyclic or polycyclic alicyclic hydrocarbon having the above carbon number. Either a monocyclic hydrocarbon group or a polycyclic hydrocarbon group may be used, and the polycyclic hydrocarbon group may be either a bridged alicyclic hydrocarbon group or a fused alicyclic hydrocarbon group, and may be either a saturated hydrocarbon group or an unsaturated hydrocarbon group. Note that a fused alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group formed by multiple alicyclic rings sharing a side (a bond between two adjacent carbon atoms).

[0071] Among the monocyclic alicyclic hydrocarbon groups, preferred saturated hydrocarbon groups include cyclopentanediyl, cyclohexanediyl, cycloheptanediyl, and cyclooctanediyl groups, while preferred unsaturated hydrocarbon groups include cyclopentenediyl, cyclohexenediyl, cycloheptenediyl, cyclooctenediyl, and cyclodecenediyl groups. Preferred polycyclic alicyclic hydrocarbon groups are bridged alicyclic saturated hydrocarbon groups, such as bicyclo[2.2.1]heptane-2,2-diyl (norbornane-2,2-diyl), bicyclo[2.2.2]octane-2,2-diyl, and tricyclo[3.3.1.1]heptane-2,2-diyl. 3,7 ]Decane-2,2-diyl group (adamantane-2,2-diyl group) and the like are preferred.

[0072] The above L 1 Examples of the divalent linking group represented by the formula (I) include an alkanediyl group, a cycloalkanediyl group, an alkenediyl group, * -R LA O-, * -R LB COO-, etc. (* indicates a bond on the oxygen side.) Some or all of the hydrogen atoms in these groups may be substituted with halogen atoms such as fluorine atoms or chlorine atoms, cyano groups, etc.

[0073] The alkanediyl group is preferably an alkanediyl group having 1 to 8 carbon atoms.

[0074] Examples of the cycloalkanediyl group include monocyclic cycloalkanediyl groups such as a cyclopentanediyl group and a cyclohexanediyl group, and polycyclic cycloalkanediyl groups such as a norbornanediyl group and an adamantanediyl group. The cycloalkanediyl group is preferably a cycloalkanediyl group having 5 to 12 carbon atoms.

[0075] 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.

[0076] the above * -R LA O-R LA Examples of the alkyl group include the above-mentioned alkanediyl group, the above-mentioned cycloalkanediyl group, and the above-mentioned alkenediyl group. * -R LB COO-R LB Examples of the arenediyl group include the above-mentioned alkanediyl group, cycloalkanediyl group, alkenediyl group, and arenediyl group. Examples of the arenediyl group include a phenylene group, a tolylene group, and a naphthylene group. The arenediyl group is preferably an arenediyl group having 6 to 15 carbon atoms.

[0077] Among these, R 8 is an alkyl group having 1 to 4 carbon atoms, and R 9 and R 10 The alicyclic structure formed by combining these together with the carbon atoms to which they are bonded is preferably a polycyclic or monocyclic cycloalkane structure. 1 is a single bond or * -R LA Preferably, R is O-. LA is preferably an alkanediyl group.

[0078] Examples of the structural unit (a2-1) include structural units represented by the following formulas (2-1) to (2-6) (hereinafter also referred to as "structural units (a2-1-1) to (a2-1-6)").

[0079] [ka] [ka]

[0080] In the above formulas (a2-1-1) to (a2-1-6), R 7 ~R 10 is the same as in the above formula (2). i and j each independently represent an integer of 1 to 4. In addition, the cycloalkyl ring in formula (a2-1-3) may be substituted with a halogen atom.

[0081] In the above formulas (a2-1-5) to (a2-1-6), n A is 0 or 1.

[0082] i and j are preferably 1. 8 ~R 10 is preferably a methyl group, an ethyl group, an isopropyl group, a t-butyl group or a phenyl group.

[0083] Further, examples of the structural unit (a2-1) include structural units represented by the following formulas (2-7) to (2-8) (hereinafter also referred to as "structural units (a2-1-7) to (a2-1-8)").

[0084] [ka]

[0085] In the above formulas (2-7) to (2-8), R αf R are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. βfare each independently a hydrogen atom or a chain alkyl group having 1 to 5 carbon atoms. h1 is an integer of 1 to 4.

[0086] Above R βf is preferably a hydrogen atom, a methyl group, or an ethyl group. h1 is preferably 1 or 2.

[0087] Also, the above R βf A plurality of R may together form a single alicyclic structure. For example, two R βf Examples include those in which both form a single cyclohexane structure or a benzene ring structure.

[0088] Of these, the structural unit (a2-1) is preferably the structural unit (a2-1-1), the structural unit (a2-1-2), the structural unit (a2-1-3), the structural unit (a2-1-4), or the structural unit (a2-1-7), and more preferably a structural unit having a 1-alkylcycloalkyl group, a structural unit having a 1-arylcycloalkyl group, a structural unit having a cycloalkenyl group, a structural unit having a 1-alkyladamantyl group, a structural unit having an arylalkyl group, or a structural unit having a substituted or unsubstituted cycloalkylalkyl group.

[0089] The resin (A0) may contain one type of structural unit (a2) or a combination of two or more types.

[0090] The lower limit of the content of the structural unit (a2) is preferably 10 mol%, more preferably 15 mol%, even more preferably 20 mol%, and particularly preferably 30 mol%, based on all structural units constituting the base resin (A0). The upper limit of the content is preferably 90 mol%, more preferably 80 mol%, even more preferably 75 mol%, and particularly preferably 70 mol%. By keeping the content of the structural unit (a2) within the above range, the pattern formability of the radiation-sensitive resin composition can be further improved.

[0091] [Structural unit (a3)] The structural unit (a3) ​​is a structural unit containing a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination thereof. Resin (A0) can have appropriate polarity by further containing the structural unit (a3) ​​in addition to the structural unit (a1) and the structural unit (a2). As a result, the radiation-sensitive resin composition can form a finer resist pattern with excellent cross-sectional rectangularity as a chemically amplified resist material. Here, the lactone structure refers to a structure having one ring (lactone ring) containing a group represented by -OC(O)-. The cyclic carbonate structure refers to a structure having one ring (cyclic carbonate ring) containing a group represented by -OC(O)-O-. The sultone structure refers to a structure having one ring (sultone ring) containing a group represented by -OS(O)2-.

[0092] Examples of the structural unit (a3) ​​include structural units represented by the following formula:

[0093] [ka]

[0094] [ka]

[0095] [ka]

[0096] [ka]

[0097] In the above formula, R AL is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0098] Above R ALAs the alkyl group, a hydrogen atom and a methyl group are preferred, and a methyl group is more preferred, from the viewpoint of copolymerizability of the monomer that gives the structural unit (a3).

[0099] Of these, the structural unit (a3) ​​is preferably a structural unit containing a norbornane lactone structure, a structural unit containing an oxanorbornane lactone structure, a structural unit containing a γ-butyrolactone structure, a structural unit containing an ethylene carbonate structure, or a structural unit containing a norbornane sultone structure, and more preferably a structural unit derived from norbornane lactone-yl (meth)acrylate, a structural unit derived from oxanorbornane lactone-yl (meth)acrylate, a structural unit derived from cyano-substituted norbornane lactone-yl (meth)acrylate, a structural unit derived from norbornane lactone-yloxycarbonylmethyl (meth)acrylate, a structural unit derived from butyrolactone-3-yl (meth)acrylate, or a structural unit derived from butyrolactone-3-yl (meth)acrylate. More preferred are structural units derived from norbornane sulton-4-yl (meth)acrylate, structural units derived from 3,5-dimethylbutyrolactone-3-yl (meth)acrylate, structural units derived from 4,5-dimethylbutyrolactone-4-yl (meth)acrylate, structural units derived from 1-(butyrolactone-3-yl)cyclohexene-1-yl (meth)acrylate, structural units derived from ethylene carbonate-ylmethyl (meth)acrylate, structural units derived from cyclohexene carbonate-ylmethyl (meth)acrylate, structural units derived from norbornane sulton-yl (meth)acrylate, and structural units derived from norbornane sulton-yloxycarbonylmethyl (meth)acrylate.

[0100] When the resin (A0) contains the structural unit (a3), the lower limit of the content of the structural unit (a3) ​​relative to all structural units constituting the resin (A0) is preferably 1 mol%, more preferably 10 mol%, even more preferably 20 mol%, and particularly preferably 25 mol%. Meanwhile, the upper limit of the content is preferably 70 mol%, more preferably 65 mol%, even more preferably 60 mol%, and particularly preferably 55 mol%. By keeping the content within the above range, a resist pattern that is finer and has excellent rectangular cross-sectional shape can be formed.

[0101] [Structural unit (a4)] The resin (A0) may appropriately contain a structural unit (also referred to as a structural unit (a4)) other than the above structural units (a1) to (a3). Examples of the structural unit (a4) include structural units having a fluorine atom, an alcoholic hydroxyl group, a carboxy group, a cyano group, a nitro group, a sulfonamide group, etc. Among these, structural units having a fluorine atom, structural units having an alcoholic hydroxyl group, and structural units having a carboxy group are preferred, and structural units having a fluorine atom and structural units having an alcoholic hydroxyl group are more preferred.

[0102] When the resin (A0) contains the structural unit (a4), the lower limit of the content of the structural unit (a4) relative to all structural units constituting the resin (A0) is preferably 1 mol%, more preferably 5 mol%, and even more preferably 10 mol%. On the other hand, the upper limit of the content is preferably 50 mol%, more preferably 40 mol%, and even more preferably 30 mol%. By setting the content of the other structural units within the above range, the solubility of the resin (A0) in the developer can be made more appropriate. If the content of the other structural units exceeds the above upper limit, pattern formability may be reduced.

[0103] In the resin (A0) of the present invention, for example, (i) a repeating unit of hydroxystyrene obtained by polymerizing a hydroxystyrene monomer protected with an alkali-hydrolyzable group and then hydrolyzing the polymerized hydroxystyrene monomer, and (ii) a repeating unit obtained by directly polymerizing the hydroxystyrene monomer, can both be considered as the structural unit (a1). Furthermore, (iii) a repeating unit obtained by polymerizing a hydroxystyrene monomer in which the hydroxyl group is protected with a group that dissociates upon exposure to EUV or an electron beam (EB) can be considered as the "structural unit (a2)."

[0104] The content of resin (A0) is usually 85% by mass or more of the total solid content of the radiation-sensitive resin composition. It is preferably 95% by mass or more, more preferably 99% by mass or more, even more preferably 99.9% by mass or more, and particularly preferably 99.99% by mass or more. Here, "solid content" refers to all components contained in the radiation-sensitive resin composition excluding (B) solvent.

[0105] (Method for synthesizing resin (A0)) The resin (A0) serving as the base resin can be synthesized, for example, by polymerizing monomers that provide the respective structural units in an appropriate solvent using a radical polymerization initiator or the like.

[0106] Examples of the radical polymerization initiator include azo radical initiators such as azobisisobutyronitrile (AIBN), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and dimethyl 2,2'-azobisisobutyrate; and peroxide radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, and cumene hydroperoxide. Among these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferred, with AIBN being more preferred. These radical initiators can be used alone or in combination.

[0107] Examples of solvents used in the polymerization reaction 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; ketones such as acetone, methyl ethyl ketone, 4-methyl-2-pentanone, and 2-heptanone; ethers such as tetrahydrofuran, dimethoxyethanes, and diethoxyethanes; and alcohols such as methanol, ethanol, 1-propanol, 2-propanol, and 4-methyl-2-pentanol. These solvents may be used alone or in combination.

[0108] The reaction temperature in the polymerization reaction is usually 40° C. to 150° C., and preferably 50° C. to 120° C. The reaction time is usually 1 hour to 48 hours, and preferably 1 hour to 24 hours.

[0109] The molecular weight of the base resin (A0) is not particularly limited, but the weight average molecular weight (Mw) of the base resin as measured by gel permeation chromatography (GPC) in terms of polystyrene is preferably 1,000 to 50,000, more preferably 2,000 to 30,000, even more preferably 3,000 to 15,000, and particularly preferably 4,000 to 12,000. If the Mw of the resin (A0) is below the lower limit, the heat resistance of the resulting resist film may be reduced. If the Mw of the resin (A0) is above the upper limit, the developability of the resist film may be reduced.

[0110] The ratio (Mw / Mn) of Mw to the polystyrene-equivalent number average molecular weight (Mn) of the base resin (A0) 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.

[0111] The Mw and Mn of the resin in this specification are values ​​measured using gel permeation chromatography (GPC) under the following conditions. GPC columns: 2 G2000HXL, 1 G3000HXL, 1 G4000HXL (all manufactured by Tosoh) Column temperature: 40℃ Elution solvent: tetrahydrofuran Flow rate: 1.0mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Detector: differential refractometer Standard material: monodisperse polystyrene

[0112] (other resins) The radiation-sensitive resin composition of this embodiment may contain, as another resin, a resin having a higher mass content of fluorine atoms than the base resin (hereinafter also referred to as a "high-fluorine content resin"). When the radiation-sensitive resin composition contains a high-fluorine content resin, the high-fluorine content resin can be unevenly distributed in the surface layer of the resist film relative to the base resin, and as a result, the state of the resist film surface and the component distribution in the resist film can be controlled to a desired state.

[0113] The high-fluorine-containing resin preferably has, for example, a structural unit represented by the following formula (3) (hereinafter also referred to as "structural unit (a5)"). [ka]

[0114] In the above formula (3), R 13 is a hydrogen atom, a methyl group, or a trifluoromethyl group. G is a single bond, an oxygen atom, a sulfur atom, -COO-, -SO2ONH-, -CONH-, or -OCONH-. R 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.

[0115] Above R13 As the alkyl group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (a5), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred.

[0116] Above G L As the group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (a5), a single bond and —COO— are preferred, and —COO— is more preferred.

[0117] 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.

[0118] Above R 14 Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (I) include a monocyclic or polycyclic hydrocarbon group having 3 to 20 carbon atoms in which some or all of the hydrogen atoms have been substituted with fluorine atoms.

[0119] Above R 14 As the alkyl group, a fluorinated chain hydrocarbon group is preferable, a fluorinated alkyl group is more preferable, and a 2,2,2-trifluoroethyl group, a 1,1,1,3,3,3-hexafluoropropyl group, and a 5,5,5-trifluoro-1,1-diethylpentyl group are even more preferable.

[0120] When the high-fluorine-content resin has the structural unit (a5), the lower limit of the content of the structural unit (a5) is preferably 10 mol%, more preferably 15 mol%, even more preferably 20 mol%, and particularly preferably 25 mol%, based on all structural units constituting the high-fluorine-content resin. The upper limit of this content is preferably 60 mol%, more preferably 50 mol%, and even more preferably 40 mol%. By setting the content of the structural unit (a5) within the above range, the mass content of fluorine atoms in the high-fluorine-content resin can be more appropriately adjusted, thereby further promoting uneven distribution of fluorine atoms in the surface layer of the resist film.

[0121] The high-fluorine-content resin may have a fluorine atom-containing structural unit represented by the following formula (f-1) (hereinafter also referred to as structural unit (a6)) in addition to the structural unit (a5): By having the structural unit (f-1), the high-fluorine-content resin has improved solubility in an alkaline developer, and can suppress the occurrence of development defects. [ka]

[0122] The structural unit (a6) 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 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 of this hydrocarbon group E Oxygen atom, sulfur atom, -NR dd -, a carbonyl group, -COO-, or -CONH- is bonded to the hydrocarbon group, or a structure in which some of the hydrogen atoms in the 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.

[0123] When the structural unit (a6) has an alkali-soluble group (x), R F is a hydrogen atom, and A 1 is an oxygen atom, -COO-* or -SO2O-*. * is R F The binding site of W is shown. 1 A is 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. Eis 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 (a6) has an alkali-soluble group (x), it is possible to increase the affinity for an alkaline developer and suppress development defects. As the structural unit (a6) 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.

[0124] When the structural unit (a6) 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-* or -SO2O-*. R aa is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. * is R F The binding site of W is shown. 1 R is a single bond or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. E A is a single bond or a divalent organic group having 1 to 20 carbon atoms. 1 When is -COO-* or -S02O-*, W 1 or R F is A 1 A has a fluorine atom on the carbon atom bonded to or adjacent to A. 1 is an oxygen atom, W 1 , R E is a single bond, and R D R is a hydrocarbon group with 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, multiple R E , W 1 , A 1 and R Fmay be the same or different. When the structural unit (a6) has an alkali dissociable group (y), the surface of the resist film changes from hydrophobic to hydrophilic in the alkaline development step. As a result, affinity to the developer is significantly increased, and development defects can be more efficiently suppressed. As the structural unit (a6) having an alkali dissociable group (y), A 1 is -COO-* and R F Or W 1 It is particularly preferred that both of them have a fluorine atom.

[0125] R C As the structural unit (a6), from the viewpoint of copolymerizability of the monomer that gives the structural unit (a6), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred.

[0126] 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 more preferably a group having a norbornane lactone structure.

[0127] When the high-fluorine-content resin has the structural unit (a6), the lower limit of the content of the structural unit (a6) relative to all structural units constituting the high-fluorine-content resin is preferably 10 mol%, more preferably 20 mol%, even more preferably 30 mol%, and particularly preferably 35 mol%. The upper limit of this content is preferably 90 mol%, more preferably 75 mol%, and even more preferably 60 mol%. By ensuring that the content of the structural unit (a6) falls within the above range, the water repellency of the resist film during immersion exposure can be further improved.

[0128] The lower limit of Mw of the high fluorine content resin is preferably 1,000, more preferably 2,000, further preferably 3,000, and particularly preferably 5,000. The upper limit of Mw is preferably 50,000, more preferably 30,000, further preferably 20,000, and particularly preferably 15,000.

[0129] The lower limit of Mw / Mn of the high fluorine content resin is usually 1, and more preferably 1.1. The upper limit of the Mw / Mn is usually 5, and is preferably 3, more preferably 2, and even more preferably 1.7.

[0130] The lower limit of the content of the high-fluorine-content resin is preferably 0.1% by mass, more preferably 0.5% by mass, even more preferably 1% by mass, and still more preferably 1.5% by mass, based on the total solid content in the radiation-sensitive resin composition. The upper limit of the content is preferably 20% by mass, more preferably 15% by mass, even more preferably 10% by mass, and particularly preferably 7% by mass.

[0131] The lower limit of the content of the high-fluorine content resin is preferably 0.1 parts by mass, more preferably 0.5 parts by mass, even more preferably 1 part by mass, and particularly preferably 1.5 parts by mass, relative to 100 parts by mass of the base resin, and the upper limit of the content is preferably 15 parts by mass, more preferably 10 parts by mass, even more preferably 8 parts by mass, and particularly preferably 5 parts by mass.

[0132] By setting the content of the high-fluorine-containing resin within the above range, the high-fluorine-containing resin can be more effectively distributed unevenly on the surface layer of the resist film, thereby further improving the water repellency of the surface of the resist film during immersion lithography. The radiation-sensitive resin composition may contain one or more high-fluorine-containing resins.

[0133] (Method for synthesizing high fluorine content resin) The high fluorine content resin can be synthesized by the same method as the above-mentioned method for synthesizing the base resin.

[0134] ((B) Solvent) The radiation-sensitive resin composition contains a solvent. The solvent is not particularly limited as long as it can dissolve or disperse at least the resin, the radiation-sensitive acid generator, and optional components that may be contained as desired.

[0135] Examples of the solvent include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

[0136] Examples of alcohol-based solvents include: Monoalcohol 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 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; Examples include polyhydric alcohol partially etherified solvents obtained by etherifying some of the hydroxy groups of the above polyhydric alcohol solvents.

[0137] Examples of ether solvents include: dialkyl ether solvents such as diethyl ether, dipropyl ether, and dibutyl ether; cyclic ether solvents such as tetrahydrofuran and tetrahydropyran; Aromatic ring-containing ether solvents such as diphenyl ether and anisole (methyl phenyl ether); Examples include polyhydric alcohol ether solvents obtained by etherifying the hydroxy groups of the above polyhydric alcohol solvents.

[0138] 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: Examples include 2,4-pentanedione, acetonylacetone, and acetophenone.

[0139] Examples of the amide solvent include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; Examples of the solvent include chain amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0140] Examples of ester solvents include: Monocarboxylic acid ester solvents such as n-butyl acetate and ethyl lactate; polyhydric alcohol partial ether acetate solvents such as diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate; Lactone solvents such as γ-butyrolactone and valerolactone; Carbonate solvents such as diethyl carbonate, ethylene carbonate, and propylene carbonate; Examples of suitable solvents include polyvalent carboxylic acid diesters such as propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoacetate, ethyl lactate, and diethyl phthalate.

[0141] Examples of hydrocarbon solvents include: Aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; Examples of the solvent include aromatic hydrocarbon solvents such as benzene, toluene, di-isopropylbenzene, and n-amylnaphthalene.

[0142] Among these, ester-based solvents and ketone-based solvents are preferred, polyhydric alcohol partial ether acetate-based solvents, cyclic ketone-based solvents and lactone-based solvents are more preferred, and propylene glycol monomethyl ether acetate, cyclohexanone and γ-butyrolactone are even more preferred. The radiation-sensitive resin composition may contain one or more solvents.

[0143] ((C) Radiation-sensitive acid generator) The radiation-sensitive resin composition of the present invention may contain a radiation-sensitive acid generator. (C) The radiation-sensitive acid generator is preferably an onium salt compound, more preferably a sulfonium salt compound or an iodonium salt compound. Known compounds can be used as such onium salt compounds.

[0144] In the present invention, when the radiation-sensitive resin composition (A) contains a radiation-sensitive acid generator (C), the amount of the radiation-sensitive acid generator is preferably small, and the amount of the radiation-sensitive acid generator in the radiation-sensitive resin composition (A) is preferably 0.1 mass % or less, more preferably 0.05 mass % or less, and even more preferably 0.01 mass % or less, based on the total amount of components other than the solvent (B). On the other hand, the lower limit of the amount of the radiation-sensitive acid generator may be, for example, 0.0001 mass % or 0.00001 mass %, but it is desirable that the composition contains no radiation-sensitive acid generator (C) (0 mass %).

[0145] As described above, the present invention does not require that the structural unit (a2) undergo dissociation (e.g., elimination) or a change in solubility due to the presence of an acid during the exposure step or the acid generated from the radiation-sensitive acid generator upon exposure. Furthermore, by not including or substantially not including the radiation-sensitive acid generator (C) in the radiation-sensitive resin composition or resist film of the present invention, the constituent components of the resist film can be simplified, improving uniformity and suppressing adverse effects at the interface between exposed and unexposed areas due to the acid generated during the exposure step. As a result, various resist performances can be more reliably improved. Therefore, it is particularly desirable that the radiation-sensitive acid generator (C) is not included or is substantially not included in the radiation-sensitive resin composition or resist film of the present invention.

[0146] (Other optional ingredients) The radiation-sensitive resin composition may contain other optional components in addition to the above components. Examples of the other optional components include an acid diffusion controller, a crosslinking agent, a localization promoter, a surfactant, an alicyclic skeleton-containing compound, and a sensitizer. These other optional components may be used alone or in combination of two or more.

[0147] ((D) Acid diffusion controller) The radiation-sensitive resin composition may optionally contain an acid diffusion controller. The acid diffusion controller controls the diffusion of acid generated from the radiation-sensitive acid generator upon exposure in the resist film, thereby suppressing undesirable chemical reactions in unexposed regions. The storage stability of the resulting radiation-sensitive resin 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 exposure time between exposure and development can be suppressed, resulting in a radiation-sensitive resin composition with excellent process stability.

[0148] (Crosslinking agent) The crosslinking agent is a compound having two or more functional groups, which causes a crosslinking reaction in the polymer component by an acid-catalyzed reaction in the baking step after the floodwise exposure step, thereby increasing the molecular weight of the polymer component and reducing the solubility of the patternwise exposed area in a developer. Examples of the functional group include a (meth)acryloyl group, a hydroxymethyl group, an alkoxymethyl group, an epoxy group, and a vinyl ether group.

[0149] (Uneven distribution promoter) The uneven distribution promoter has the effect of more efficiently unevenly distributing the high-fluorine-content resin on the resist film surface. By incorporating this uneven distribution promoter into the radiation-sensitive resin composition, the amount of the high-fluorine-content resin added can be reduced compared to conventional methods. Therefore, while maintaining the lithography performance of the radiation-sensitive resin composition, it is possible to further suppress elution of components from the resist film into the immersion medium and perform immersion exposure at higher speeds through high-speed scanning. As a result, it is possible to improve the hydrophobicity of the resist film surface, which suppresses immersion-related defects such as watermark defects. Examples of compounds that can be used as such uneven distribution promoters include low-molecular-weight compounds having a dielectric constant of 30 to 200 and a boiling point of 100°C or higher at 1 atmosphere. Specific examples of such compounds include lactone compounds, carbonate compounds, nitrile compounds, and polyhydric alcohols.

[0150] (surfactant) The surfactant has the effect of improving coating properties, striations, developability, etc. Examples of surfactants include nonionic surfactants such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, and polyethylene glycol distearate; commercially available products include KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, and Polyflow No. 95 (all manufactured by Kyoeisha Chemical), F-Top EF301, EF303, EF352 (all manufactured by Tochem Products), Megafac F171, F173 (all manufactured by DIC), Fluorad FC430, FC431 (all manufactured by Sumitomo 3M), Asahiguard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (all manufactured by Asahi Glass Co., Ltd.) The content of the surfactant in the radiation-sensitive resin composition is usually 2 parts by mass or less per 100 parts by mass of the resin.

[0151] (alicyclic skeleton-containing compounds) The alicyclic skeleton-containing compound has the effect of improving dry etching resistance, pattern shape, adhesion to the substrate, and the like.

[0152] Examples of the alicyclic skeleton-containing compound include: Adamantane derivatives such as 1-adamantanecarboxylic acid, 2-adamantanone, and t-butyl 1-adamantanecarboxylate; deoxycholate esters such as t-butyl deoxycholate, t-butoxycarbonylmethyl deoxycholate, and 2-ethoxyethyl deoxycholate; Lithocholate esters such as t-butyl lithocholate, t-butoxycarbonylmethyl lithocholate, and 2-ethoxyethyl lithocholate; Examples include 3-[2-hydroxy-2,2-bis(trifluoromethyl)ethyl]tetracyclo[4.4.0.1(2,5).1(7,10)]dodecane, 2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo[4.2.1.0(3,7)]nonane, etc. The content of the alicyclic skeleton-containing compound in the radiation-sensitive resin composition is usually 5 parts by mass or less per 100 parts by mass of the resin.

[0153] (sensitizer) The sensitizer acts to increase the amount of acid generated from the radiation-sensitive acid generator or the like, and has the effect of improving the "apparent sensitivity" of the radiation-sensitive resin composition.

[0154] Examples of sensitizers include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, and phenothiazines. These sensitizers may be used alone or in combination of two or more. The content of the sensitizer in the radiation-sensitive resin composition is usually 2 parts by mass or less per 100 parts by mass of the resin.

[0155] <Method for preparing radiation-sensitive resin composition> The radiation-sensitive resin composition (A) can be prepared, for example, by mixing the resin (A0), the solvent (B), and, if necessary, other components in a predetermined ratio. After mixing, the radiation-sensitive resin composition is preferably filtered, for example, through a filter with a pore size of about 0.05 μm. The solids concentration of the radiation-sensitive resin composition is usually 0.1% to 50% by mass, preferably 0.5% to 30% by mass, and more preferably 1% to 20% by mass.

[0156] <Method for forming a resist pattern> The method for forming a resist pattern according to the present invention comprises: (C) a step (1) of forming a resist film having a radiation-sensitive acid generator content of 0.1% by mass or less (hereinafter also referred to as the "resist film forming step"); a step (2) of exposing the resist film to EUV or electron beam (EB) (hereinafter also referred to as the "exposure step"); and The method includes a step (3) (hereinafter also referred to as a "developing step") of developing the resist film exposed in the above step (2).

[0157] According to the above-mentioned method for forming a resist pattern, a resist film or the like having a content of the radiation-sensitive acid generator (C) of 0.1 mass % or less, which is formed using the above-mentioned radiation-sensitive resin composition or the like, can be used, and therefore a resist pattern can be formed that can exhibit excellent levels of sensitivity and resolution in the exposure step. Each step will be described below.

[0158] [Resist film formation process] In this step (the above step (1)), a resist film is formed from the above radiation-sensitive resin composition or the like. Examples of substrates on which the resist film is formed include conventionally known substrates such as silicon wafers, silicon dioxide wafers, and aluminum-coated wafers. Alternatively, an organic or inorganic anti-reflective coating, as disclosed in, for example, Japanese Patent Publication No. 6-12452 or Japanese Patent Application Laid-Open No. 59-93448, may be formed on the substrate. Examples of coating methods include spin coating, casting coating, and roll coating. After coating, pre-baking (PB) may be performed, if necessary, to volatilize the solvent in the coating film. The PB temperature is typically 60°C to 140°C, and preferably 80°C to 120°C. The PB time is typically 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds. The thickness of the resist film formed is preferably 10 nm to 1,000 nm, and more preferably 10 nm to 500 nm.

[0159] When performing immersion exposure, regardless of whether the radiation-sensitive resin composition contains a water-repellent polymer additive such as a high-fluorine-content resin, a protective film for immersion exposure that is insoluble in the immersion medium may be provided on the formed resist film to prevent direct contact between the immersion medium and the resist film. The protective film for immersion exposure may be either a solvent-removable protective film that is removed with a solvent before the development step (see, for example, JP-A No. 2006-227632), or a developer-removable protective film that is removed simultaneously with development in the development step (see, for example, WO2005-069076 and WO2006-035790). However, from the viewpoint of throughput, it is preferable to use a developer-removable protective film for immersion exposure.

[0160] When the next exposure step is carried out using radiation with a wavelength of 50 nm or less, it is preferable to use a resin having the structural unit (a1) and the structural unit (a2) as the base resin in the composition.

[0161] Furthermore, the above-mentioned step (1) is a step of forming a resist film containing 0.1 mass % or less of the radiation-sensitive acid generator (C). The resist film can be formed by any known method. The resist film can be formed, for example, by using the above-mentioned resin (A0). More specifically, for example, the resist film can be easily formed from a radiation-sensitive resin composition (A) in which the radiation-sensitive acid generator (C) is present in an amount of 0.1 mass % or less relative to the total amount of components other than the solvent (B). Alternatively, for example, the resist film can be easily formed from a radiation-sensitive resin composition (A) that does not contain a radiation-sensitive acid generator.

[0162] The resist film formed in step (1) has a radiation-sensitive acid generator (C) content of 0.1% by mass or less, but when the resist film contains a radiation-sensitive acid generator (C), the amount of the radiation-sensitive acid generator (C) is preferably small, and the amount of the radiation-sensitive acid generator (C) in the resist film is preferably 0.05% by mass or less, and more preferably 0.01% by mass or less. Meanwhile, the lower limit of the amount of the radiation-sensitive acid generator (C) is preferably 0% by mass or less.

[0163] As described above, the present invention does not require that the structural unit (a2) undergo dissociation (e.g., elimination) or a change in solubility due to, for example, the presence of acid during the exposure step or the acid generated from the radiation-sensitive acid generator upon exposure. Furthermore, by not including or substantially not including the radiation-sensitive acid generator (C) in the resist film of the present invention, the components of the resist film can be simplified, improving uniformity and suppressing adverse effects at the interface between exposed and unexposed areas due to the acid generated during the exposure step. As a result, various resist performances can be more reliably improved. Therefore, it is particularly desirable that the radiation-sensitive acid generator (C) is not included in or substantially not included in the resist film of the present invention.

[0164] [Exposure process] In this step (the above step (2)), the resist film formed in the above step (1), the resist film forming step, is exposed to radiation through a photomask (or, in some cases, through an immersion medium such as water). Examples of radiation used for exposure include extreme ultraviolet (EUV) and electron beams (EB), depending on the line width of the desired pattern.

[0165] When exposure is performed by immersion exposure, examples of the immersion medium used include water and fluorine-based inert liquids. The immersion medium 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. When water is used, a small proportion of an additive that reduces the surface tension of the water and increases its surfactant power may be added. This additive is preferably one that does not dissolve the resist film on the wafer and has negligible effect on the optical coating on the underside of the lens. Distilled water is preferably used as the water.

[0166] In the present invention, after the exposure, a difference in solubility in a developer occurs between the exposed and unexposed areas. Since the present invention does not contain or substantially does not contain a radiation-sensitive acid generator, there is essentially no need to perform post-exposure baking (PEB) after the exposure for the purpose of promoting dissociation of acid-dissociable groups in the resin or the like by the acid generated from the radiation-sensitive acid generator. However, in all embodiments of the present invention, PEB as a heat treatment may be performed after the exposure for a purpose other than generating acid from the radiation-sensitive acid generator by exposure. The PEB temperature for the heat treatment is, for example, 50°C to 180°C, e.g., 80°C to 130°C. The PEB time for the heat treatment is, for example, 5 seconds to 600 seconds, e.g., 10 seconds to 300 seconds.

[0167] [Development process] In this step (step (3) above), the resist film exposed in the exposure step (step (2) above) is developed. This allows a predetermined resist pattern to be formed. After development, the resist film is generally washed with a rinse liquid such as water or alcohol, and then dried.

[0168] In the above step (3), in one embodiment, a negative pattern can be formed by developing with an organic solvent.

[0169] In the above step (3), in one embodiment, a positive pattern can be formed by developing with an alkaline developer.

[0170] In the case of alkaline development, the developer used for the development may be, for example, an alkaline aqueous solution containing at least one alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, or 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, a TMAH aqueous solution is preferred, and a 2.38 mass % TMAH aqueous solution is more preferred.

[0171] 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 organic solvents. Examples of the organic solvent include one or more of the solvents listed above as solvents for the radiation-sensitive resin composition. Among these, ester solvents and ketone solvents are preferred. As the ester solvent, acetate ester solvents are preferred, with n-butyl acetate and amyl acetate being more preferred. As the ketone solvent, 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.

[0172] Examples of development methods include a method in which a substrate is immersed in a tank filled with developer for a certain period of time (dip method), a method in which developer is piled up on the surface of the substrate by surface tension and left to stand for a certain period of time (puddle method), a method in which developer is sprayed onto the surface of the substrate (spray method), and a method in which developer is continuously dispensed by scanning a developer dispensing nozzle at a constant speed over a substrate that is rotating at a constant speed (dynamic dispense method).

[0173] <Substrate processing method, metal film pattern manufacturing method> The method for processing a substrate according to the present invention includes: The method further includes a step (4-1) of forming a pattern on a substrate using the resist pattern formed by any of the above methods as a mask.

[0174] Further, the method for producing a metal film pattern according to the present invention comprises the steps of: The method further includes a step (4-2) of forming a metal film using the resist pattern formed by any of the above methods as a mask.

[0175] The substrate processing method and the metal film pattern manufacturing method use the radiation-sensitive resin composition or the resist film, and therefore can function as a resist film in a conventional exposure step or the like even without substantially containing a conventional radiation-sensitive acid generator (C), thereby enabling the processing of a high-quality substrate pattern and a high-quality metal film pattern, respectively.

[0176] The above step (4-1) is a step of forming a pattern on a substrate using a resist pattern formed by any of the methods as a mask. Examples of methods for forming a pattern on a substrate using a resist pattern as a mask include a method of forming a resist pattern on a substrate and then forming a pattern on the substrate by a method such as dry etching in areas where there is no resist, and a method of forming a resist pattern and then depositing substrate components by CVD or the like in areas where there is no resist, or depositing metal by a method such as electroless plating to form part or all of the substrate.

[0177] The above-mentioned step (4-2) is a step of forming a metal film using a resist pattern formed by any of the methods as a mask. Examples of the method of forming a metal film using a resist pattern as a mask include a method of forming a resist pattern, and then depositing metal by a method such as electroless plating on areas where there is no resist to form a metal film, and a method of forming a resist pattern on a metal film, and removing the metal film from areas where there is no resist by a method such as dry etching to form a metal film. [Example]

[0178] The present invention will now be described in detail with reference to examples, but the present invention is not limited to the following examples. Measurement methods for various physical properties are shown below.

[0179] [Measurement of weight average molecular weight (Mw), number average molecular weight (Mn) and dispersity (Mw / Mn)] The Mw and Mn of the polymers used in the examples were measured by gel permeation chromatography (GPC) using Tosoh GPC columns (two G2000HXL columns, one G3000HXL column, and one G4000HXL column) under the following analytical conditions: flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran, sample concentration: 1.0 mass%, sample injection volume: 100 μL, column temperature: 40°C, detector: differential refractometer, with monodisperse polystyrene as the standard. The polydispersity (Mw / Mn) was calculated from the measurement results of Mw and Mn.

[0180] <Synthesis of Polymer [A]> 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 where the total mass of the monomers used is taken as 100 parts by mass, and mol % refers to a value where the total number of moles of the monomers used is taken as 100 mol %.

[0181] [ka]

[0182] [Synthesis Example 1] (Synthesis of Polymer (A-1)) Compound (M-1) and compound (M-4) were dissolved in 1-methoxy-2-propanol (200 parts by mass relative to the total monomer amount) so that the molar ratio was 40 / 60. Next, azobisisobutyronitrile was added as an initiator in an amount of 6 mol% relative to the total monomer amount to prepare a monomer solution. Meanwhile, 1-methoxy-2-propanol (100 parts by mass relative to the total monomer amount) was added to an empty reaction vessel and heated to 85°C with stirring. Next, the monomer solution prepared above was added dropwise over 3 hours, and then heated at 85°C for another 3 hours, allowing the polymerization reaction to proceed for a total of 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to room temperature.

[0183] The cooled polymerization solution was then poured into hexane (500 parts by mass relative to the polymerization solution), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane (100 parts by mass relative to the polymerization solution), 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.

[0184] After the reaction was completed, the remaining solvent was distilled off, and the resulting solid was dissolved in acetone (100 parts by mass). The solution was added dropwise to 500 parts by mass of water to solidify the resin, and the resulting solid was filtered off. The resulting solid was dried at 50°C for 12 hours to synthesize a white powdery polymer (A-1).

[0185] The resulting polymer (A-1) had an Mw of 5,700 and an Mw / Mn ratio of 1.61.

[0186] [Synthesis Examples 2 to 18] (Synthesis of Polymers (A-2) to (A-12)) Polymers (A-2) to (A-12) and (A-14) were synthesized by selecting monomers according to the formulations in Table 1 and carrying out the same operations as in Synthesis Example 1. Table 1 also shows the Mw and Mw / Mn of the resulting polymers (A-2) to (A-12).

[0187] The formulations and preparation results of each synthesis example are shown in Table 1 below.

[0188] [Table 1]

[0189] <Preparation of Radiation-Sensitive Resin Composition> The acid generators [C], acid diffusion controllers [D], and solvents [B] used in the preparation of the radiation-sensitive resin compositions of the Examples and Comparative Examples are shown below.

[0190] [[C] Acid generator] The structural formula of the acid generator is shown below. [ka]

[0191] [[D] Acid diffusion control agent] The structural formula of the acid diffusion controller is shown below. [ka]

[0192] [[B] Organic solvent] The organic solvents are shown below. B-1: Propylene glycol monomethyl ether acetate B-2: Propylene glycol 1-monomethyl ether

[0193] [Example 1] 100 parts by mass of (A-1) as the polymer [A], 12,200 parts by mass of (B-1) as the organic solvent [B], and 5,200 parts by mass of (B-2) were mixed and filtered through a 20 nm membrane filter to prepare a radiation-sensitive resin composition (R-1).

[0194] [Examples 2 to 18 and Comparative Example 1] (Radiation-sensitive resin compositions (R-2) to (R-18) and (CR-1)) Each radiation-sensitive resin composition was prepared in the same manner as in Example 1, except that the types and amounts of each component shown in Table 2 below were used.

[0195] [Table 2]

[0196] [Resist pattern formation by EUV exposure and alkaline development] Each radiation-sensitive resin composition listed in Table 2 was applied to the surface of a 12-inch silicon wafer on which a 20-nm-thick underlayer film (AL412 (Brewer Science)) had been formed, using a spin coater (CLEAN TRACK ACT12, Tokyo Electron), and prebaked (PB) at 100°C for 60 seconds. The wafer was then cooled at 23°C for 30 seconds to form a 20-nm-thick resist film.

[0197] Next, the obtained resist film was irradiated with EUV light using an EUV exposure machine (model "NXE3300", manufactured by ASML, NA = 0.33, illumination conditions: Dipole). After irradiation, the resist film was developed using a 2.38 wt% TMAH aqueous solution at 23°C for 30 seconds, then washed with water and dried to form a positive line-and-space resist pattern.

[0198] [evaluation] The sensitivity and resolution of each radiation-sensitive resin composition were evaluated by measuring each of the resist patterns formed above according to the methods described below. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-4100") was used to measure the resist patterns. The evaluation results are shown in Table 3 below.

[0199] [sensitivity] In forming the resist pattern, the exposure dose for forming an 18 nm line and space pattern was set as the optimum exposure dose, and this optimum exposure dose was used as the sensitivity (mJ / cm 2 The sensitivity was 100mJ / cm 2 The cases below were judged as "good", and those above 100 mJ / cm2 were judged as "poor".

[0200] [Resolution] At the above-mentioned optimum exposure dose, the size of the mask pattern forming the line and space (1L / 1S) was changed, and the dimension of the smallest resist pattern resolved was measured, and this measurement value was taken as the resolution (nm). The smaller the value, the better the resolution. Resolution can be evaluated as good when it is less than 18 nm, and as poor when it is 18 nm or more.

[0201] The results of forming each resist pattern are shown in Table 3 below.

[0202] [Table 3]

[0203] [Synthesis Example 19] (Synthesis of Polymer (A-19)) Compounds (M-5) and (M-13) were dissolved in 2-butanone (200 parts by mass) at a molar ratio of 60 / 40 (mol%), and AIBN (azobisisobutyronitrile) (8 mol% relative to the total of 100 mol% of the monomers used) was added as an initiator to prepare a monomer solution. 2-butanone (100 parts by mass) was placed in an empty reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C and the monomer solution was added dropwise over 3 hours with stirring. The start of the dropwise addition marked the start of the polymerization reaction, which was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled to below 30°C with water. The cooled polymerization solution was poured into methanol (2,000 parts by mass), and the precipitated white powder was filtered off. The white powder was washed twice with methanol, filtered off, and dried at 50°C for 10 hours to obtain polymer (A-19) in the form of a white powder. The Mw of the polymer (A-19) was 5,700, and the Mw / Mn was 1.61. 13 As a result of C-NMR analysis, the content ratios of the structural units derived from (M-5) and (M-13) were 58.5 mol % and 41.5 mol %, respectively.

[0204] [Synthesis Example 20] (Synthesis of Polymer (A-20)) Polymer (A-20) was synthesized by selecting each monomer according to the recipe in Table 4 and carrying out the same operation as in Synthesis Example 1. Table 4 also shows the Mw and Mw / Mn of the obtained polymer (A-20).

[0205] The formulations and preparation results of each synthesis example are shown in Table 4 below.

[0206] [Table 4]

[0207] <Preparation of Radiation-Sensitive Resin Composition> [Example 19] (Radiation-sensitive resin composition (R-19)) 100 parts by mass of (A-19) as the polymer [A], 12,200 parts by mass of (B-1) as the organic solvent [B], and 5,200 parts by mass of (B-2) were mixed and filtered through a 20 nm membrane filter to prepare a radiation-sensitive resin composition (R-19).

[0208] [Example 20] (Radiation-sensitive resin composition (R-20)) Each radiation-sensitive resin composition was prepared in the same manner as in Example 19, except that the types and amounts of each component shown in Table 5 below were used.

[0209] [Table 5]

[0210] [Resist pattern formation by EUV exposure and alkaline development] A positive line-and-space resist pattern was formed in the same manner as described above using the radiation-sensitive resin composition (R-19) or (R-20).

[0211] [evaluation] The sensitivity and resolution of each resist pattern formed as above were evaluated in the same manner as described above, and the evaluation results are shown in Table 6 below.

[0212] [Table 6]

[0213] As shown in Tables 3 and 6, the radiation-sensitive resin compositions of the Examples all exhibited good sensitivity and resolution in the exposure step. In contrast, the radiation-sensitive resin compositions of the Comparative Examples did not exhibit the above-mentioned performance results as good as those of the Examples. Thus, it was found that the radiation-sensitive resin compositions of the Examples of the present invention were excellent in sensitivity and resolution. [Industrial Applicability]

[0214] As explained above, the radiation-sensitive resin composition and method for forming a resist pattern, etc. of the present invention are capable of exhibiting superior performance compared to conventional methods in terms of sensitivity, resolution, etc. The radiation-sensitive resin composition and method for forming a resist pattern, etc. of the present invention can be suitably used for, for example, forming fine resist patterns in lithography processes for various electronic devices such as semiconductor devices and liquid crystal devices.

Claims

1. (C) a step (1) of forming a resist film containing a radiation-sensitive acid generator in an amount of 0.1% by mass or less; (2) exposing the resist film to EUV or electron beam (EB); and A method for forming a resist pattern, comprising: a step (3) of developing the resist film exposed in the step (2), In the step (1), the resist film is formed from (A) a radiation-sensitive resin composition, The radiation-sensitive resin composition includes (A1) a resin having a structural unit (a2) including a group that dissociates upon exposure to EUV or electron beam (EB) in the absence of a radiation-sensitive acid generator, The structural unit (a2) is a structural unit having a tertiary alkyl ester moiety, The structural unit (a2) is a structural unit represented by the following formula (2): 【Chemical 1】 (In the above formula (2), R ７ is a hydrogen atom, a methyl group, or a trifluoromethyl group. R ８ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ９ and R １０ each independently represents a monovalent chain hydrocarbon group having 1 to 20 carbon atoms and substituted or unsubstituted with a fluorine atom, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms and substituted or unsubstituted with a fluorine atom, or a monovalent aromatic hydrocarbon group having 5 to 20 carbon atoms, or a divalent alicyclic group having 3 to 20 carbon atoms and substituted or unsubstituted with a fluorine atom, which is formed by combining these groups together with the carbon atoms to which they are bonded. Also, R ８ ~R １０ and / or, when the above alicyclic group is present, the alicyclic group may have an unsaturated bond. Also, R ８ ~R １０ This also includes cases where two or more of the above together form one alicyclic structure.) The content of the structural unit represented by formula (2) is 10 mol% or more relative to all structural units constituting the resin. A method for forming a resist pattern.

2. 2. The method for forming a resist pattern according to claim 1, wherein in the step (1), the resist film is formed from the radiation-sensitive resin composition (A), and the content of the radiation-sensitive acid generator (C) in the radiation-sensitive resin composition (A) is 0.1 mass% or less, based on the total mass of components other than the solvent (B).

3. 3. The method for forming a resist pattern according to claim 1, wherein in the step (1), the resist film is formed from the radiation-sensitive resin composition (A), and the radiation-sensitive resin composition (A) does not contain a radiation-sensitive acid generator.

4. 4. The method for forming a resist pattern according to claim 1, wherein the resin (A1) whose solubility changes is a resin that changes to be water-soluble or alkali-soluble.

5. 5. The method for forming a resist pattern according to claim 1, wherein in the step (3), a negative pattern is formed by developing with an organic solvent.

6. 5. The method for forming a resist pattern according to claim 1, wherein in the step (3), a positive pattern is formed by developing with an alkaline developer.

7. A method for processing a substrate, comprising the step (4-1) of forming a pattern on a substrate using a resist pattern formed by the method according to any one of claims 1 to 6 as a mask.

8. A method for producing a metal film pattern, comprising the step (4-2) of forming a metal film using the resist pattern formed by the method according to any one of claims 1 to 6 as a mask.

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