Method for forming resist pattern and radiation-sensitive resin composition

Abstract

To provide a method for forming a resist pattern that has excellent performance in sensitivity, resolution, etc. in an exposure step when a next-generation exposure technique is applied, and a radiation-sensitive resin composition.SOLUTION: A radiation-sensitive resin composition comprises: (A2) a resin containing a group that dissociates due to EUV or electron beam (EB) exposure; (B) a solvent; and (C) a radiation-sensitive acid generator, wherein in the radiation-sensitive resin composition, the radiation-sensitive acid generator (C) accounts for 0.1 mass% or less based on a total amount of components other than the solvent (B). The resin (A2) has a structural unit (a2) containing a group that dissociates due to EUV or electron beam (EB) exposure in the absence of the radiation-sensitive acid generator (A1). The structural unit (a2) is a structural unit that has a tertiary alkyl ester moiety.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 in the method. [Background technology]

[0002] Photolithography techniques using resist compositions are used for forming fine circuits in semiconductor elements. As a typical procedure, for example, an acid is generated by exposing a coating of the resist composition to radiation through a mask pattern, and a difference in solubility of the resin in an alkaline or organic developer is generated between an exposed portion and an unexposed portion by a reaction catalyzed by the acid, thereby forming a resist pattern on a substrate.

[0003] In the above photolithography technology, pattern miniaturization is being promoted by using short-wavelength radiation such as ArF excimer lasers, or by combining this radiation with liquid immersion lithography. As a next-generation technology, the use of even shorter-wavelength radiation such as electron beams, X-rays, and EUV (extreme ultraviolet) is being attempted, and resist materials containing styrene-based resins with improved radiation absorption efficiency are also being considered (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-52294 A Summary of the Invention [Problem to be solved by the invention]

[0005] The above-mentioned next-generation technologies also require resist properties equal to or better than those of conventional resists 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 intensive research into solving the above problem, the present inventors discovered that the above object can be achieved by adopting the following configuration, and thus completed the present invention.

[0008] That is, in one embodiment, the present invention provides (C) forming a resist film having a radiation-sensitive acid generator content of 0.1% by mass or less (1); (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 above step (2).

[0009] The method for forming a resist pattern of the present invention includes step (1) of forming a resist film containing 0.1 mass % or less of the radiation-sensitive acid generator (C), and therefore can exhibit excellent levels of sensitivity, resolution, etc. in the exposure step. Although the scope of the present invention is not necessarily limited by this presumption, it is presumed that the mechanism of action for the manifestation of the above-mentioned effect is that by setting the content of the radiation-sensitive acid generator (C) in the resist film to 0.1 mass % or less, the components constituting the resist film are simplified to improve uniformity, and adverse effects at the boundary 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 includes the steps of: 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 a resin whose solubility changes upon exposure to EUV or electron beam (EB) in the absence of (A1) a radiation-sensitive acid generator. By having the above-mentioned structure, the resist film can function as a resist film in a conventional exposure step or the like even if it does not substantially contain (C) a radiation-sensitive acid generator as in the conventional case, and as a result, various resist properties can be improved more reliably.

[0011] In one embodiment, the method for forming a resist pattern of the present invention includes the steps of: In the above step (1), the resist film is preferably formed from the radiation-sensitive resin composition (A), and the radiation-sensitive acid generator (C) in the radiation-sensitive resin composition (A) is preferably 0.1 mass % or less based on the total of the components other than the solvent (B). By having the above-mentioned configuration, a resist film that is substantially free of the radiation-sensitive acid generator (C) can be more easily formed, and various resist properties can be more reliably improved.

[0012] In one embodiment, the method for forming a resist pattern of the present invention includes the steps of: In the above step (1), the resist film is preferably formed from the radiation-sensitive resin composition (A), and the radiation-sensitive resin composition (A) does not contain a radiation-sensitive acid generator. By having the above-mentioned configuration, a resist film that does not substantially contain the radiation-sensitive acid generator (C) 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 includes the steps of: The (A1) resin whose solubility changes is preferably a resin whose solubility changes to 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 acid generator (C) in the radiation-sensitive resin composition is 0.1 mass% or less relative to the total of the components other than the solvent (B), so that the sensitivity, resolution, etc. in the exposure step can be exhibited at an excellent level. Although the scope of the invention is not necessarily limited by this presumption as the mechanism of action of the above effect, it is presumed that by setting 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 the components other than the solvent (B), the components constituting the resist film are simplified to improve uniformity, and adverse effects at the boundary between the 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 composition is composed of only (A2) a resin containing a group that dissociates upon exposure to EUV or electron beam (EB), and (B) a solvent. By having the above-mentioned composition, the composition can function as a resist film in a conventional exposure step or the like even if it does not substantially contain (C) a radiation-sensitive acid generator as in the conventional case, and as a result, various resist properties can be improved more reliably.

[0017] In one embodiment, the radiation-sensitive resin composition of the present invention comprises: The resin containing a dissociable 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 improved more reliably. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, the 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, 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 they do not impair the effects of the present invention.

[0020] (Resin (A0)) The resin (A0) in the present invention is a resin that can be used as 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) or the like. By using the resin (A0), it can be used as a resist film in the exposure step and development step without substantially relying on the acid generated by exposure from the radiation-sensitive acid generator as in the conventional case. Furthermore, the components of the resist film can be simplified to improve uniformity, and adverse effects on the boundary between exposed and unexposed areas due to the acid generated during the exposure step can be suppressed, 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 an acid generated by a conventional radiation-sensitive acid generator upon exposure. The above-mentioned "solubility changes" includes the property of increasing or decreasing the solubility in a developer.

[0023] Examples of the (A1) resin whose solubility changes include resins that change to water-soluble or alkali-soluble. Examples of the resins that change to water-soluble or alkali-soluble include resins that regenerate or generate hydroxyl groups, carboxyl groups, amino groups, ionic groups, sulfo groups, etc. 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, (A2) a resin containing a group dissociated by exposure to EUV or an electron beam (EB) refers to a resin containing a group that dissociates in the resin structure by elimination reaction or the like upon exposure to EUV or an electron beam (EB), without substantially depending on an acid generated by exposure from a conventional radiation-sensitive acid generator. Furthermore, the above-mentioned "dissociable group" can be, for example, a group that can generate a hydroxyl group, a carboxyl group, an amino group, an ionic group, a sulfo group, etc., upon dissociation upon exposure.

[0026] Examples of (A2) resins containing a group that dissociates upon exposure to EUV or electron beam (EB) include 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 (a carboxylate group, -COOH). -The hydroxyl group structure generated by dissociation includes an alcoholic hydroxyl group, a phenolic hydroxyl group (-OH) and a salt thereof (-O - ) etc.

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

[0028] Further, preferred examples of the structural unit having a polar group include those including 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) can also be an assembly 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 is also referred to as the "base resin").

[0030] The resin (A0) serving as the base resin may have 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. The resin (A0) can adjust the solubility in a developer more appropriately by having the structural unit (a1) and other structural units as necessary, and as a result, the resist performance such as the sensitivity and resolution of the radiation-sensitive resin composition can be improved. In addition, when EUV, electron beams, etc. are used as the radiation to be irradiated in the exposure step in the resist pattern forming method, the structural unit (a1) in the resin (A0) contributes to improving the etching resistance and the difference in solubility in the developer between the exposed and unexposed areas (dissolution contrast). In particular, the resin (A0) can be suitably applied to 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 R 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 from 1 to 3. f1 +n f2 is less than or equal to 5. af is an integer from 0 to 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 monovalent hydrocarbon groups having 1 to 20 carbon atoms, groups containing a divalent heteroatom-containing group between the carbon atoms of this hydrocarbon group or at the bond-side terminal of this hydrocarbon group, and groups in which some or all of the hydrogen atoms in this group and the hydrocarbon group have been substituted with monovalent heteroatom-containing groups.

[0039] Above R AF2 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula: Alkyl groups such as a methyl group, an ethyl group, a propyl group, and a butyl group; alkenyl groups such as ethenyl, propenyl, and butenyl; Chain hydrocarbon groups such as alkynyl groups, e.g., 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, e.g., cyclopropenyl, cyclopentenyl, cyclohexenyl, and norbornenyl; Aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, or an anthryl group; Examples include aromatic hydrocarbon groups such as aralkyl groups, eg, benzyl group, phenethyl group, and naphthylmethyl group.

[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 or an adamantyl group is even more preferable.

[0041] Examples of the divalent heteroatom-containing group include -O-, -CO-, -CO-O-, -S-, -CS-, -SO2-, -NR'-, and combinations of 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, hydroxyl group, carboxy group, cyano group, amino group, and sulfanyl group (-SH).

[0043] Among 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 preferable, and 1 is more preferable.

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

[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 any of structural units represented by the following formulas (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] Among these, the structural units (a1-1) and (a1-2) are preferred, with (a1-1) being more preferred.

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

[0053] When a monomer having a phenolic hydroxyl group such as hydroxystyrene is directly subjected to radical polymerization, the polymerization may be inhibited by the influence of the phenolic hydroxyl group. In this case, the phenolic hydroxyl group may be protected by a protecting group such as an alkali dissociable group and polymerized in such a state, and then hydrolyzed to remove the protection to obtain 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 R 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 preferable, and among them, a methyl group and a tert-butoxy group are more preferable.

[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, "in the absence of a radiation-sensitive acid generator" refers to a state 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 a hydrogen atom of a phenolic hydroxyl group is substituted with a tertiary alkyl group, and a structural unit having an acetal bond, but 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 previous paragraph are structures known in the technical field as acid dissociable groups. In the present invention, the term "acid dissociable group" refers to a group that substitutes a hydrogen atom of a carboxy group, a phenolic hydroxyl group, an alcoholic hydroxyl group, a sulfo group, or the like, and has the property of dissociating under the action of an acid. As described above, in the present invention, it is not necessary that the structural unit (a2) undergoes 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 because the resin has the structural unit (a2).

[0060] [ka]

[0061] In the above formula (2), R 7 R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 8 R is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. 9 and R 10 each independently represents a monovalent linear 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 atom 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 The present invention also includes cases where a plurality of any 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 preferable, and a methyl group is more preferable.

[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 linear or branched saturated hydrocarbon groups having 1 to 20 carbon atoms, and linear or branched unsaturated hydrocarbon groups 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 (1) include monocyclic or polycyclic saturated hydrocarbon groups, or monocyclic or polycyclic unsaturated hydrocarbon groups. Preferred examples of the monocyclic saturated hydrocarbon group include cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. Preferred examples of the polycyclic cycloalkyl group include 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 carbon atoms that are not adjacent to each other among the carbon atoms constituting the alicyclic ring are bonded by a bond 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 (1) 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 and an alicyclic hydrocarbon group having 3 to 20 carbon atoms are preferable.

[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 The present invention also includes cases where a plurality of any of the above together form one alicyclic structure.

[0070] Above R 8 ~R 10When any of a plurality of the above are combined with each other to have at least one or more cyclic structures, 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 obtained 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. It may be either a monocyclic hydrocarbon group or a polycyclic hydrocarbon group, and the polycyclic hydrocarbon group may be either a bridged alicyclic hydrocarbon group or a condensed alicyclic hydrocarbon group, or it may be either a saturated hydrocarbon group or an unsaturated hydrocarbon group. The condensed alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group formed in such a way that a plurality of alicyclic rings share 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 include 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- and the like (* indicates a bond on the oxygen side). A part or all of the hydrogen atoms of these groups may be substituted with halogen atoms such as fluorine atoms and chlorine atoms, cyano groups, and the like.

[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, the above-mentioned cycloalkanediyl group, the above-mentioned 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 It is preferable that the alicyclic structure formed by combining these together with the carbon atoms to which they are bonded is a polycyclic or monocyclic cycloalkane structure. 1 is a single bond or * -R LA O- is preferred. 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] As i and j, 1 is preferable. 8 ~R 10 As the alkyl group, a methyl group, an ethyl group, an isopropyl group, a t-butyl group or a phenyl group is preferable.

[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 is 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] In addition, the above R βf may be combined to 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), (a2-1-3), (a2-1-4) or (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 the total 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 setting 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. The resin (A0) can have an appropriate polarity by further having 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 resist pattern that is finer and has excellent rectangular cross-sectional shape 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 formulas:

[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 ALFrom the viewpoint of copolymerizability of the monomer that gives the structural unit (a3), a hydrogen atom or a methyl group is preferred, and a methyl group is more preferred.

[0099] As the structural unit (a3), of these, 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, and a structural unit containing a norbornane sultone structure are preferred, and 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 a 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 ... More preferred are structural units derived from norbornane sultone-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)cyclohexan-1-yl (meth)acrylate, structural units derived from ethylene carbonate-yl methyl (meth)acrylate, structural units derived from cyclohexene carbonate-yl methyl (meth)acrylate, structural units derived from norbornane sultone-yl (meth)acrylate, and structural units derived from norbornane sultone-yloxycarbonylmethyl (meth)acrylate.

[0100] When the resin (A0) has the structural unit (a3), the lower limit of the content of the structural unit (a3) ​​relative to the total structural units constituting the resin (A0) is preferably 1 mol%, more preferably 10 mol%, even more preferably 20 mol%, and particularly preferably 25 mol%. On the other hand, 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 setting 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)] Resin (A0) may appropriately have a structural unit (also referred to as 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, and the like. Among these, a structural unit having a fluorine atom, a structural unit having an alcoholic hydroxyl group, and a structural unit having a carboxy group are preferred, and a structural unit having a fluorine atom and a structural unit having an alcoholic hydroxyl group are more preferred.

[0102] When the resin (A0) has the structural unit (a4), the lower limit of the content ratio of the structural unit (a4) to the total 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 ratio is preferably 50 mol%, more preferably 40 mol%, and even more preferably 30 mol%. By setting the content ratio 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 ratio of the other structural units exceeds the above upper limit, the 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 polymerizing the hydroxystyrene monomer as it is, can both correspond to the above structural unit (a1). Also, (iii) a repeating unit obtained by polymerizing a hydroxystyrene monomer in which a hydroxyl group is protected with a group that dissociates upon exposure to EUV or an electron beam (EB) can correspond to the above "structural unit (a2)".

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

[0105] (Method of synthesizing resin (A0)) The resin (A0) serving as the base resin can be synthesized, for example, by polymerizing monomers which 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, and AIBN is more preferred. These radical initiators can be used alone or in combination of two or more.

[0107] Examples of the solvent 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. The solvents used in these polymerization reactions may be used alone or in combination of two or more.

[0108] The reaction temperature in the above 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) calculated based on polystyrene standards by gel permeation chromatography (GPC) 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 less than the lower limit, the heat resistance of the resulting resist film may decrease. If the Mw of the resin (A0) is more than the upper limit, the developability of the resist film may decrease.

[0110] The ratio (Mw / Mn) of Mw to the polystyrene-equivalent number average molecular weight (Mn) of the base resin (A0) measured 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] In this specification, the Mw and Mn of the resin are values ​​measured by 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 the present 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 content 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 From the viewpoint of copolymerizability of the monomer that gives the structural unit (a5), a hydrogen atom or a methyl group is preferable, and a methyl group is more preferable.

[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 preferable, and -COO- is more preferable.

[0117] Above R 14 Examples of the monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms represented by the formula (1) include linear or branched alkyl groups 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 following formula 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.

[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 further 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 the total structural units constituting the high fluorine content resin. The upper limit of the 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, and the uneven distribution of fluorine atoms in the surface layer of the resist film can be further promoted.

[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 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 R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. D is a single bond, a (s+1)-valent hydrocarbon group having 1 to 20 carbon atoms, and R of this hydrocarbon group E At the end of the side, there is an oxygen atom, a sulfur atom, and -NR dd R is a structure in which -, a carbonyl group, -COO- or -CONH- is bonded, or a structure in which some of the hydrogen atoms in the hydrocarbon group are replaced by an organic group having a hetero atom. dd represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. s represents 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 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 alkali 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 R 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, 1 is an oxygen atom, -NR aa -, -COO-* or -SO2O-*. 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 -S0-*, W 1 or R F 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 R 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, 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, the 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 Or, it is particularly preferable that both of them have a fluorine atom.

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

[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) is preferably 10 mol%, more preferably 20 mol%, further preferably 30 mol%, and particularly preferably 35 mol% based on the total structural units constituting the high fluorine content resin. The upper limit of the content is preferably 90 mol%, more preferably 75 mol%, and further preferably 60 mol%. By setting the content of the structural unit (a6) 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 mass%, more preferably 0.5 mass%, further preferably 1 mass%, and even more preferably 1.5 mass%, based on the total solid content in the radiation-sensitive resin composition. The upper limit of the content is preferably 20 mass%, more preferably 15 mass%, further preferably 10 mass%, and particularly preferably 7 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. 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 content resin within the above range, the high fluorine content resin can be more effectively unevenly distributed in the surface layer of the resist film, and as a result, the water repellency of the surface of the resist film during immersion exposure can be further improved. The radiation-sensitive resin composition may contain one or more types of high fluorine content resins.

[0133] (Method of 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 any optional components 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 of the polyhydric alcohol partially etherified solvents include those 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 of the polyhydric alcohol solvent include polyhydric alcohol ether solvents obtained by etherifying the hydroxyl groups of the above-mentioned 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, methylcyclohexanone, etc. Examples include 2,4-pentanedione, acetonylacetone, and acetophenone.

[0139] Examples of the amide solvents 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-based 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 the polyvalent carboxylic acid diester solvents include propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoacetate, ethyl lactate, and diethyl phthalate.

[0141] Examples of the hydrocarbon solvent include: Aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; Examples of the solvent include aromatic hydrocarbon solvents such as benzene, toluene, di-iso-propylbenzene, 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. As such an onium salt compound, a known compound can be used.

[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 (C) is preferably small, and the radiation-sensitive resin composition (A) preferably contains the radiation-sensitive acid generator (C) in an amount of 0.1% by mass or less, more preferably 0.05% by mass or less, and even more preferably 0.01% by 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 (C) is, for example, 0.0001% by mass or 0.00001% by mass, but it is preferable that the composition does not contain the radiation-sensitive acid generator (C) (0% by mass).

[0145] As described above, in the present invention, it is not necessary that the structural unit (a2) undergoes dissociation such as elimination or solubility change due to the presence of acid during the exposure process or the acid generated from the radiation-sensitive acid generator by exposure. In addition, 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 components of the resist film are simplified to improve uniformity, and adverse effects at the boundary between exposed and unexposed areas due to the acid generated during the exposure process are suppressed. As a result, various resist properties can be improved more reliably. Therefore, it is particularly preferable that the radiation-sensitive acid generator (C) is not included or 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 control agent) The radiation-sensitive resin composition may contain an acid diffusion controller as necessary. The acid diffusion controller controls the diffusion phenomenon in the resist film of the acid generated from the radiation-sensitive acid generator by exposure, and suppresses undesirable chemical reactions in the non-exposed region. In addition, the storage stability of the obtained radiation-sensitive resin composition is improved. Furthermore, the resolution of the resist pattern is further improved, and the line width change of the resist pattern due to the fluctuation of the delay time from exposure to development treatment can be suppressed, and a radiation-sensitive resin composition with excellent process stability can be obtained.

[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 catalysis in the baking step after the floodwise exposure step, thereby increasing the molecular weight of the polymer component and decreasing the solubility of the patternwise exposed area in the 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 making the high fluorine content resin unevenly distributed on the resist film surface more efficiently. By incorporating this uneven distribution promoter in the radiation-sensitive resin composition, the amount of the high fluorine content resin added can be reduced compared to the conventional case. Therefore, while maintaining the lithography performance of the radiation-sensitive resin composition, it is possible to further suppress the elution of components from the resist film into the immersion medium, and perform immersion exposure at a higher speed by high-speed scanning, thereby improving the hydrophobicity of the resist film surface, which suppresses immersion-induced defects such as watermark defects. Examples of the uneven distribution promoter that can be used include low-molecular compounds having a relative dielectric constant of 30 to 200 and a boiling point of 100° C. or higher at 1 atmospheric pressure. Specific examples of such compounds include lactone compounds, carbonate compounds, nitrile compounds, polyhydric alcohols, and the like.

[0150] (Surfactant) The surfactant has the effect of improving the coating property, striation, developability, etc. Examples of the surfactant 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 No. Examples include F-TOP EF301, EF303, and EF352 (all manufactured by Tochem Products), Megafac F171 and F173 (all manufactured by DIC), Fluorad FC430 and FC431 (all manufactured by Sumitomo 3M), Asahiguard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, and 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 exhibits the effect of improving dry etching resistance, pattern shape, adhesion to a 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; Deoxycholic acid esters such as t-butyl deoxycholate, t-butoxycarbonylmethyl deoxycholate, and 2-ethoxyethyl deoxycholate; Lithocholic acid esters such as t-butyl lithocholic acid, t-butoxycarbonylmethyl lithocholic acid, and 2-ethoxyethyl lithocholic acid; 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 based on 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 exerts the effect of improving the "apparent sensitivity" of the radiation-sensitive resin composition.

[0154] Examples of the sensitizer 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 having a pore size of about 0.05 μm. The solid content concentration of the radiation-sensitive resin 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.

[0156] <Method of forming resist pattern> The method for forming a resist pattern according to the present invention comprises the steps of: (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 a "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) of developing the resist film exposed in the above step (2) (hereinafter, also referred to as the "developing step").

[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, is used, so that a resist pattern capable of exhibiting excellent levels of sensitivity and resolution in the exposure step can be formed. Each step will be described below.

[0158] [Resist film formation process] In this step (step (1) above), a resist film is formed from the radiation-sensitive resin composition or the like. Examples of the substrate on which the resist film is formed include conventionally known substrates such as silicon wafers, silicon dioxide, and aluminum-coated wafers. In addition, an organic or inorganic anti-reflective film disclosed in, for example, JP-B-6-12452 and JP-A-59-93448 may be formed on the substrate. Examples of the coating method include spin coating, casting coating, and roll coating. After coating, pre-baking (PB) may be performed as necessary to volatilize the solvent in the coating film. The PB temperature is usually 60° C. to 140° C., and preferably 80° C. to 120° C. The PB time is usually 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 the presence or absence of the water-repellent polymer additive such as the high fluorine content resin in the radiation-sensitive resin composition, a protective film for immersion that is insoluble in the immersion medium may be provided on the formed resist film in order to prevent direct contact between the immersion medium and the resist film. As the protective film for immersion, 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, WO2005-069076 and WO2006-035790) may be used. However, from the viewpoint of throughput, it is preferable to use a developer-peelable protective film for immersion.

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

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

[0162] The resist film formed in the above step (1) has a content of the radiation-sensitive acid generator (C) of 0.1% by mass or less, but when the resist film contains the radiation-sensitive acid generator (C), the amount of the radiation-sensitive acid generator (C) is preferably small, and for example, the amount of the radiation-sensitive acid generator (C) in the resist film is more preferably 0.05% by mass or less, and even more preferably 0.01% by mass or less. On the other hand, the lower limit of the blending amount is preferably no radiation-sensitive acid generator (C) (0% by mass).

[0163] As described above, in the present invention, for example, the presence of acid during the exposure process or the acid generated from the radiation-sensitive acid generator by exposure does not require the structural unit (a2) to undergo dissociation such as elimination or change in solubility. In addition, 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 are simplified to improve uniformity, and adverse effects at the boundary between exposed and unexposed areas due to the acid generated during the exposure process are suppressed. As a result, various resist properties can be improved more reliably. Therefore, it is particularly preferable that the radiation-sensitive acid generator (C) is not included or is substantially not included in the resist film of the present invention.

[0164] [Exposure process] In this step (step (2) above), the resist film formed in the resist film forming step (1) above 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 EUV (extreme ultraviolet) and electron beam (EB), depending on the line width of the desired pattern.

[0165] When the exposure is performed by immersion exposure, the immersion medium used may be, for example, water, a fluorine-based inert liquid, etc. The immersion medium is preferably a liquid that is transparent to the exposure wavelength and has a temperature coefficient of refractive index as small 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 water and increases the surface activity may be added. This additive is preferably one that does not dissolve the resist film on the wafer and has a negligible effect on the optical coating on the lower surface of the lens. Distilled water is preferably used as the water to be used.

[0166] In the present invention, after the exposure, the solubility in the developer is different between the exposed and unexposed areas. Since the present invention does not contain or substantially does not contain a radiation-sensitive acid generator, it is not necessary to perform post-exposure baking (PEB) for the purpose of promoting dissociation of an acid-dissociable group of a resin or the like by an acid generated from the radiation-sensitive acid generator after the exposure. However, in all embodiments of the present invention, PEB as a heat treatment is not excluded after the exposure for a purpose other than the purpose of generating an acid from the radiation-sensitive acid generator by exposure. The PEB temperature as the heat treatment is, for example, 50°C to 180°C, such as 80°C to 130°C. The PEB time as the heat treatment is, for example, 5 seconds to 600 seconds, such as 10 seconds to 300 seconds.

[0167] [Development process] In this step (step (3) above), the resist film exposed in the exposure step (2) above is developed. This allows a desired 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, examples of the developer used in the development include an alkaline aqueous solution in which at least one of alkaline compounds 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 is dissolved. Among these, an aqueous TMAH solution is preferred, and a 2.38 mass % aqueous TMAH 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, or solvents containing organic solvents. Examples of the organic solvent include one or more of the solvents listed as the solvents for the radiation-sensitive resin composition described above. Among these, ester solvents and ketone solvents are preferred. As the ester solvent, acetate solvents are preferred, and n-butyl acetate and amyl acetate are more preferred. As the ketone solvent, chain ketones are preferred, and 2-heptanone is more preferred. The content of the organic solvent in the developer is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more. Examples of components other than the organic solvent in the developer include water and silicone oil.

[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 (paddle method), a method in which developer is sprayed onto the substrate surface (spray method), and a method in which developer is continuously dispensed by scanning a developer dispensing nozzle at a constant speed over a substrate 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 steps of: The method further includes a step (4-1) of forming a pattern on a substrate using the resist pattern formed by any one 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 one of the above methods as a mask.

[0175] The above-mentioned substrate processing method and the above-mentioned metal film pattern manufacturing method use the above-mentioned radiation-sensitive resin composition or the above-mentioned resist film, and therefore can function as a resist film in a conventional exposure step or the like even if they do not substantially contain the 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 the method of 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 on the portion where there is no resist, and a method of forming a resist pattern, and then depositing a substrate component by CVD or the like on the portion where there is no resist, or depositing a metal by a method such as electroless plating to form a part or the whole 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 attaching a metal to the parts where there is no resist by a method such as electroless plating to form a metal film, and a method of forming a resist pattern on a metal film, and removing the metal film from the parts where there is no resist by a method such as dry etching to form a metal film. EXAMPLES

[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 (G2000HXL: 2, G3000HXL: 1, and G4000HXL: 1) under the following analytical conditions: flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran, sample concentration: 1.0 mass%, sample injection amount: 100 μL, column temperature: 40° C., detector: differential refractometer, with monodisperse polystyrene as the standard. The dispersity (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 when the total mass of the monomers used is taken as 100 parts by mass, and % by mole refers to a value when 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 while stirring. Next, the monomer solution prepared above was dropped over 3 hours, and then heated at 85°C for another 3 hours, and the polymerization reaction was carried out for a total of 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to room temperature.

[0183] Then, the cooled polymerization solution was 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 100 parts by mass of hexane 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 the hydrolysis reaction was carried out at 70°C for 6 hours while stirring.

[0184] After the reaction was completed, the remaining solvent was distilled off, and the obtained solid was dissolved in acetone (100 parts by mass). The solution was dropped into 500 parts by mass of water to coagulate the resin, and the obtained solid was filtered off. The mixture 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 recipes 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 obtained 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] [Formation of resist patterns by EUV exposure and alkaline development] Each radiation-sensitive resin composition shown 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", 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 resist pattern formed as described above according to the following method. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-4100") was used to measure the length of the resist pattern. 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 defined as the optimum exposure dose, and this optimum exposure dose was defined as the sensitivity (mJ / cm 2 The sensitivity was 100mJ / cm 2 The cases below were judged as "good", and those exceeding 100 mJ / cm2 were judged as "poor".

[0200] [Resolution] At the above optimum exposure dose, the dimensions of the smallest resist pattern resolved when the size of the mask pattern forming the line and space (1L / 1S) was changed was measured, and this measurement value was taken as the resolution (nm). The smaller the value of the resolution, the better it is. 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) so that the molar ratio was 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 while stirring. The start of the dropwise addition was set as the start time of the polymerization reaction, and the polymerization reaction was carried out for 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled with water to 30°C or less. The cooled polymerization solution was poured into methanol (2,000 parts by mass), and the precipitated white powder was filtered off. The white powder that was filtered off was washed twice with methanol, filtered off, and dried at 50°C for 10 hours to obtain a white powdery polymer (A-19). 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 contents 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 recipes 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] [Formation of resist patterns 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. 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 in the Examples all had good sensitivity and resolution in the exposure step. In contrast, the radiation-sensitive resin compositions in the Comparative Examples did not perform as well as the Examples in the above-mentioned performance. Thus, it was found that the radiation-sensitive resin compositions in the Examples of the present invention were excellent in sensitivity and resolution. [Industrial Applicability]

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

Claims

1. A radiation-sensitive resin composition comprising: (A2) a resin containing a group that dissociates upon exposure to EUV or 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 a total amount of components other than the solvent (B), The resin (A2) has a structural unit (a2) including a group that dissociates upon exposure to EUV or electron beam (EB) in the absence of the radiation-sensitive acid generator (A1), The structural unit (a2) is a structural unit having a tertiary alkyl ester moiety. Radiation sensitive resin composition.

2. A radiation-sensitive resin composition consisting of only (A2) a resin containing a group that dissociates upon exposure to EUV or electron beam (EB), and (B) a solvent.

3. 3. The radiation-sensitive resin composition according to claim 2, wherein the group in the resin (A2) that dissociates upon exposure to an electron beam (EB) is a structural unit having a tertiary alkyl ester moiety.

4. The radiation-sensitive resin composition according to any one of claims 1 to 3, wherein the resin (A2) containing a dissociable group is a resin containing a group that dissociates to generate a carboxylic acid structure.

5. The radiation-sensitive resin composition according to any one of claims 1 to 4, wherein the resin (A2) containing a dissociable group contains a structural unit represented by the following formula (2): 【Chemistry 1】 In the formula (2), R ７ R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ８ R is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. ９ and R １０ each independently represents a monovalent linear hydrocarbon group having 1 to 20 carbon atoms which is substituted or unsubstituted with a fluorine atom, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms which is 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 which is substituted or unsubstituted with a fluorine atom and which is constituted by combining these groups together with the carbon atom 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 The present invention also includes a case where a plurality of any of the above together form one alicyclic structure.

6. The R ９ and R １０ The radiation-sensitive resin composition according to claim 5, wherein are combined together and constituted together with the carbon atom to which they are bonded, a divalent saturated or unsaturated alicyclic group having 3 to 20 carbon atoms.

7. The R ８ represents a hydrogen atom, a fluorine atom-substituted or unsubstituted monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a carbon atom-substituted or unsubstituted monovalent aromatic hydrocarbon group.

8. The radiation-sensitive resin composition according to any one of claims 1 to 7, wherein the (A2) resin containing a dissociable group contains a structural unit having a group that dissociates to generate a carboxylic acid structure, a structural unit having a phenolic hydroxyl group, and at least one structural unit selected from a structural unit having a polar group.

9. 9. The radiation-sensitive resin composition according to claim 8, wherein the structural unit having a polar group includes 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.

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