Radiation-sensitive resin composition and pattern forming method

Abstract

Provided are a radiation-sensitive resin composition capable of exhibiting adequate levels of sensitivity, LWR performance, and CDU performance, and a method for forming a pattern. This radiation-sensitive resin composition contains a solvent and an onium salt compound including a structure represented by formula (1). (In formula (1), Rf1 and Rf2 each independently represent a fluorine atom or a fluorinated monovalent hydrocarbon group having 1-20 carbon atoms.　R1 represents a hydrogen atom, a monovalent hydrocarbon group having 1-20 carbon atoms, a fluorine atom, or a fluorinated monovalent hydrocarbon group having 1-20 carbon atoms.　R2, R3, R4, R5, R6, and R7 each independently represent a hydrogen atom or a monovalent hydrocarbon group having 1-20 carbon atoms.　n1 is an integer of 0-4. When there are more than one of each of Rf1 and Rf2, such Rf1s and Rf2s are identical or different from each other.　n2 is an integer of 0-4. When there are more than one of each of R1 and R2, such R1s and R2s are identical or different from each other.　n1+n2 equals an integer of 2-8.　n3 is an integer of 0-5. When there are more than one of each of R3 and R4, such R3s and R4s are identical or different from each other.　X1 and X2 each independently represent an oxygen atom or a sulfur atom.　Each * represents a bond with another structure.　Z+ represents a radiation-sensitive monovalent onium cation.)

Description

[Technical field]

[0001] The present invention relates to a radiation-sensitive resin composition and a pattern forming 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] The above photolithography technology is promoting pattern miniaturization by using short-wavelength radiation such as ArF excimer lasers, and further by using liquid immersion lithography, in which exposure is performed with the space between the lens of the exposure device and the resist film filled with a liquid medium. Lithography using even shorter-wavelength radiation such as electron beams, X-rays, and EUV (extreme ultraviolet) is also being considered as a next-generation technology.

[0004] As efforts toward further technological advances continue, attempts are being made to improve the sensitivity, resolution, etc., of photoacid generators, which are the main components of resist compositions. For example, acid generators that can provide strong acidity by substituting the proximal carbon of a sulfonic acid group with fluorine are being studied (Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-12684 A Summary of the Invention [Problem to be solved by the invention]

[0006] In these efforts toward next-generation technologies, resist performances equivalent to or better than those of conventional resists are required in terms of sensitivity, LWR (Line Width Roughness) performance indicating the variation in line width of the resist pattern, CDU (Critical Dimension Uniformity) performance, etc. However, existing radiation-sensitive resin compositions do not provide these properties at a sufficient level.

[0007] An object of the present invention is to provide a radiation-sensitive resin composition and a pattern forming method that are capable of exhibiting sufficient levels of sensitivity, LWR performance, and CDU performance. [Means for solving the problem]

[0008] 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.

[0009] That is, in one embodiment, the present invention provides An onium salt compound having a structure represented by the following formula (1): Solvent and The present invention relates to a radiation-sensitive resin composition comprising the above compound. [ka] (In the above formula (1), R f1 and R f2 are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. R 1 is a hydrogen atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, a fluorine atom, or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. R 2 , R 3 , R 4 , R 5 , R 6 and R 7 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. n1 is an integer from 0 to 4.f1 and R f2 If there are multiple of each, multiple R f1 and R f2 are the same or different from each other. n2 is an integer from 0 to 4. 1 and R 2 If there are multiple of each, multiple R 1 and R 2 are the same or different from each other. Here, n1+n2 is an integer from 2 to 8. n3 is an integer from 0 to 5. 3 and R 4 If there are multiple of each, multiple R 3 and R 4 are the same or different from each other. X 1 and X 2 are each independently an oxygen atom or a sulfur atom. Each * represents a bond to another structure. Z + is a monovalent radiation-sensitive onium cation.

[0010] The radiation-sensitive resin composition contains an onium salt compound (hereinafter also referred to as "compound (1)") containing a structure represented by the above formula (1) as a radiation-sensitive acid generator, and therefore can exhibit excellent sensitivity, LWR performance, and CDU performance during resist pattern formation. Although not bound by any theory, the reason for this is presumed to be as follows. By bonding an electron-withdrawing group to the carbon atom to which the sulfo group is bonded, the generated acid can be strongly oxidized, and by introducing an ester bond and two adjacent (thio)ether structures into the skeleton portion, the diffusion length of the acid and the affinity with the resin can be made at an appropriate level, and the synergistic effect of these can exhibit the desired resist performances. The organic group refers to a group containing at least one carbon atom.

[0011] In another embodiment, the present invention provides a method for producing a resist film by directly or indirectly applying the radiation-sensitive resin composition onto a substrate, exposing the resist film to light; developing the exposed resist film with a developer; The present invention relates to a pattern forming method comprising the steps of:

[0012] In this pattern formation method, the above-mentioned radiation-sensitive resin composition, which has excellent sensitivity, LWR performance and CDU performance, is used, so that a high-quality resist pattern can be efficiently formed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, the embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments.

[0014] <Radiation sensitive resin composition> The radiation-sensitive resin composition according to this embodiment (hereinafter, also simply referred to as the "composition") contains compound (1) and a solvent. It further preferably contains a resin, and if necessary, contains an acid diffusion controller. The composition may contain other optional components as long as they do not impair the effects of the present invention. By containing compound (1) as a radiation-sensitive acid generator, the radiation-sensitive resin composition can be imparted with high levels of sensitivity LWR performance and CDU performance.

[0015] (Compound (1)) Compound (1) includes a structure represented by the following formula (1) (hereinafter, also referred to as "specific partial structure"). The form of compound (1) is not particularly limited as long as it includes the specific partial structure, and examples thereof include a resin form in which the other structure to which the specific partial structure is bonded is a resin (resin skeleton), and the specific partial structure is a part of the resin structure (hereinafter, a resin having a specific partial structure is also referred to as "acid-generating resin"). Examples of the compound (1) include a compound form in which the other structure to which the specific partial structure is bonded is an arbitrary group, and the specific partial structure is a part of a low molecular weight compound. When the composition includes compound (1) in a resin form (when compound (1) is an acid-generating resin), it may or may not include a resin that is a suitable component described later. As long as it includes the specific partial structure, the acid-generating resin is treated as compound (1). When compound (1) is in a compound form, the composition preferably includes a resin described later. Whether in a resin form or a compound form, it may include one specific partial structure or two or more specific partial structures. When it includes two or more specific partial structures, the multiple specific partial structures may be the same or different from each other. Compound (1) is preferably in the form of a compound.

[0016] [ka]

[0017] In the above formula (1), R f1 and R f2 are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. R 1 is a hydrogen atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, a fluorine atom, or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. R 2 , R 3 , R 4 , R 5 , R 6 and R 7 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. n1 is an integer from 0 to 4. f1 and R f2If there are multiple of each, multiple R f1 and R f2 are the same or different from each other. n2 is an integer from 0 to 4. 1 and R 2 If there are multiple of each, multiple R 1 and R 2 are the same or different from each other. Here, n1+n2 is an integer from 2 to 8. n3 is an integer from 0 to 5. 3 and R 4 If there are multiple of each, multiple R 3 and R 4 are the same or different from each other. X 1 and X 2 are each independently an oxygen atom or a sulfur atom. Each * represents a bond to another structure. Z + is a monovalent radiation-sensitive onium cation.

[0018] R f1 and R f2 Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms and a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0019] Examples of the monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms include Fluorinated alkyl groups such as a trifluoromethyl group, a 2,2,2-trifluoroethyl group, a pentafluoroethyl group, a 2,2,3,3,3-pentafluoropropyl group, a 1,1,1,3,3,3-hexafluoropropyl group, a heptafluoro n-propyl group, a heptafluoro i-propyl group, a nonafluoro n-butyl group, a nonafluoro i-butyl group, a nonafluoro t-butyl group, a 2,2,3,3,4,4,5,5-octafluoro n-pentyl group, a tridecafluoro n-hexyl group, and a 5,5,5-trifluoro-1,1-diethylpentyl group; Fluorinated alkenyl groups, such as a trifluoroethenyl group and a pentafluoropropenyl group; Examples of the fluorinated alkynyl groups include a fluoroethynyl group and a trifluoropropynyl group.

[0020] Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms include fluorinated cycloalkyl groups such as a fluorocyclopentyl group, a difluorocyclopentyl group, a nonafluorocyclopentyl group, a fluorocyclohexyl group, a difluorocyclohexyl group, an undecafluorocyclohexylmethyl group, a fluoronorbornyl group, a fluoroadamantyl group, a fluorobornyl group, a fluoroisobornyl group, a fluorotricyclodecyl group, and a fluorotetracyclodecyl group; Examples of the fluorinated cycloalkenyl group include a fluorocyclopentenyl group and a nonafluorocyclohexenyl group.

[0021] As the above-mentioned fluorinated hydrocarbon group, the above-mentioned monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms is preferred, and a monovalent fluorinated chain hydrocarbon group having 1 to 10 carbon atoms is more preferred. As the monovalent fluorinated chain hydrocarbon group having 1 to 10 carbon atoms, a group having 1 to 10 carbon atoms among the above-mentioned monovalent fluorinated chain hydrocarbon groups having 1 to 20 carbon atoms can be suitably used.

[0022] R f1 and R f2 From the viewpoints of the degree of freedom of the peripheral structure of the sulfo group and the acidity of the generated acid, a fluorine atom is preferred.

[0023] R 1 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0024] Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms 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.

[0025] The alicyclic hydrocarbon group having 3 to 20 carbon atoms may be a monocyclic or polycyclic saturated hydrocarbon group, or a monocyclic or polycyclic unsaturated hydrocarbon group. As the monocyclic saturated hydrocarbon group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, or a cyclooctyl group is preferable. As the polycyclic cycloalkyl group, a bridged alicyclic hydrocarbon group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, or a tetracyclododecyl group is preferable. 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.

[0026] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include Examples of the alkyl group 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.

[0027] R 1 As the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by the formula: f1 and R f2 The monovalent fluorinated hydrocarbon groups having 1 to 20 carbon atoms exemplified in the above can be suitably used.

[0028] R 2 , R 3 , R 4 , R 5 , R 6 and R 7 As the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula: 1 The monovalent hydrocarbon groups having 1 to 20 carbon atoms exemplified in the above can be suitably used.

[0029] R 1 , R 2 , R 3 , R 4 , R 5 , R 6 and R 7 are each independently preferably a hydrogen atom or a linear or branched saturated hydrocarbon group having 1 to 20 carbon atoms. 1and R 2 It is preferable that both of are hydrogen atoms.

[0030] n1 and n2 are each independently preferably an integer of 1 to 4, more preferably an integer of 1 to 3, and further preferably 1 or 2. It is particularly preferable that n1 and n2 are both 1.

[0031] n1+n2 is preferably an integer of 2 to 4, more preferably 2 or 3, and even more preferably 2.

[0032] n3 is preferably an integer of 0 to 3, more preferably an integer of 0 to 2, further preferably 0 or 1, and particularly preferably 0.

[0033] X 1 and X 2 Preferably, both are oxygen atoms.

[0034] In the above formula (1), the above Z + Examples of the monovalent radiation-sensitive onium cation represented by the formula (X-1) include radiation-decomposable onium cations containing elements such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, and Bi, and examples thereof include sulfonium cations, tetrahydrothiophenium cations, iodonium cations, phosphonium cations, diazonium cations, and pyridinium cations. Among these, sulfonium cations and iodonium cations are preferred. The sulfonium cations and iodonium cations are preferably represented by the following formulas (X-1) to (X-6).

[0035] [ka]

[0036] [ka]

[0037] [ka]

[0038] [ka]

[0039] [ka]

[0040] [ka]

[0041] In the above formula (X-1), R a1 , R a2 and R a3 each independently represents a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or an alkoxycarbonyloxy group, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a hydroxy group, a halogen atom, -OSO2-R P , -SO2-R Q Or -SR T or a ring structure formed by combining two or more of these groups together. The ring structure may contain a heteroatom such as O or S between the carbon-carbon bonds that form the skeleton. R P , R Q and R T are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k1, k2, and k3 are each independently an integer of 0 to 5. R a1 ~R a3 And R P , R Q and R TIf there are multiple R a1 ~R a3 And R P , R Q and R T may be the same or different.

[0042] In the above formula (X-2), R b1 is a substituted or unsubstituted linear or branched alkyl or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxy group. k is 0 or 1. k When is 0, k4 is an integer from 0 to 4, and n k When is 1, k4 is an integer from 0 to 7. b1 If there are multiple, multiple R b1 may be the same or different, and multiple R b1 R may represent a ring structure formed by combining with each other. b2 L is a substituted or unsubstituted linear or branched alkyl group having 1 to 7 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 or 7 carbon atoms. C is a single bond or a divalent linking group. k5 is an integer of 0 to 4. R b2 If there are multiple, multiple R b2 may be the same or different, and multiple R b2 may represent a ring structure formed by combining with each other. q is an integer of 0 to 3. In the formula, S + The ring structure containing the following may contain a heteroatom such as O or S between the carbon-carbon bonds that form the backbone.

[0043] In the above formula (X-3), R c1 , R c2 and R c3 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms.

[0044] In the above formula (X-4), R g1is a substituted or unsubstituted linear or branched alkyl or alkoxy group having 1 to 20 carbon atoms, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxy group. k is 0 or 1. k2 When is 0, k10 is an integer from 0 to 4, and n k2 When is 1, k10 is an integer from 0 to 7. R g1 If there are multiple, multiple R g1 may be the same or different, and multiple R g1 R may represent a ring structure formed by combining with each other. g2 and R g3 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or an alkoxycarbonyloxy group, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a hydroxy group, a halogen atom, or a ring structure formed by combining these groups together. k11 and k12 are each independently an integer of 0 to 4. R g2 and R g3 If there are multiple R g2 and R g3 may be the same or different.

[0045] In the above formula (X-5), R d1 and R d2 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or an alkoxycarbonyl group, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a halogen atom, a halogenated alkyl group having 1 to 4 carbon atoms, a nitro group, or a ring structure formed by combining two or more of these groups together. k6 and k7 are each independently an integer of 0 to 5. R d1 and R d2 If there are multiple R d1 and R d2 may be the same or different.

[0046] In the above formula (X-6), R e1 and R e2 are each independently a halogen atom, a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k8 and k9 are each independently an integer of 0 to 4.

[0047] Specific examples of the radiation-sensitive onium cation include, but are not limited to, structures of the following formulas.

[0048] [ka]

[0049] [ka]

[0050] Compound (1) may have a structure in which any anion moiety containing a specific partial structure is combined with any radiation-sensitive onium cation.

[0051] When compound (1) is in the form of a compound, the compound is preferably an onium salt compound represented by the following formula (1-1) (hereinafter also referred to as "compound (1-1)") or an onium salt compound represented by the following formula (1-2) (hereinafter also referred to as "compound (1-2)"). [ka]

[0052] In the above formulas (1-1) and (1-2), R f1 , R f2 , R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7, n1, n2, n3, X 1 , X 2 and Z + has the same meaning as the above formula (1). R 8a and R 9a are each independently a monovalent organic group having 1 to 40 carbon atoms. R 8b and R 9b are each independently a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms, or R 8b and R 9b represent a ring structure having 3 to 20 ring members formed by combining with each other and the carbon atom to which they are bonded. n4 is an integer from 1 to 4. 8b and R 9b If there are multiple of each, multiple R 8b and R 9b are the same or different from each other.

[0053] R 8a , R 9a , R 8b and R 9b The monovalent organic group having 1 to 40 carbon atoms represented by the formula (I) is not particularly limited, and may be any of a chain structure, a cyclic structure, or a combination thereof. The chain structure may be a chain hydrocarbon group, whether saturated or unsaturated, linear or branched. The cyclic structure may be a cyclic hydrocarbon group, whether alicyclic, aromatic, or heterocyclic. Among them, the monovalent organic group is preferably a substituted or unsubstituted monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, or a combination thereof. In addition, examples of the monovalent organic group include a group having a chain structure or a group having a cyclic structure in which some or all of the hydrogen atoms contained therein are substituted with a substituent, and a group containing CO, CS, O, S, SO2, or NR', or a combination of two or more of these, between the carbon atoms of these groups. R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

[0054] Examples of the substituent that replaces some or all of the hydrogen atoms in the organic group include halogen atoms such as fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms; hydroxy groups; carboxy groups; cyano groups; nitro groups; alkyl groups, alkoxy groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, acyl groups, acyloxy groups, or groups in which the hydrogen atoms of these groups are replaced with halogen atoms; oxo groups (=O), and the like.

[0055] The monovalent chain hydrocarbon group having 1 to 20 carbon atoms, the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include R 1 Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms, the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, which are exemplified in the above. Among these, the above alicyclic hydrocarbon group is preferably a monovalent monocyclic alicyclic group having 3 to 10 carbon atoms or a monovalent polycyclic alicyclic group having 6 to 14 carbon atoms.

[0056] The heterocyclic cyclic hydrocarbon group includes a group in which one hydrogen atom is removed from an aromatic heterocyclic structure and a group in which one hydrogen atom is removed from an alicyclic heterocyclic structure. The heterocyclic structure also includes a 5-membered aromatic structure that has aromaticity due to the introduction of a heteroatom. Examples of the heteroatom include an oxygen atom, a nitrogen atom, and a sulfur atom.

[0057] Examples of the aromatic heterocyclic structure include Aromatic heterocyclic structures containing oxygen atoms, such as furan, pyran, benzofuran, and benzopyran; Nitrogen atom-containing aromatic heterocyclic structures such as pyrrole, imidazole, pyridine, pyrimidine, pyrazine, indole, quinoline, isoquinoline, acridine, phenazine, and carbazole; Sulfur-containing aromatic heterocyclic structures such as thiophene; Examples of the heterocyclic ring include aromatic heterocyclic structures containing a plurality of heteroatoms, such as thiazole, benzothiazole, thiazine, and oxazine.

[0058] Examples of the alicyclic heterocyclic structure include Oxygen atom-containing alicyclic heterocyclic structures such as oxirane, tetrahydrofuran, tetrahydropyran, dioxolane, and dioxane; Nitrogen-containing alicyclic heterocyclic structures such as aziridine, pyrrolidine, piperidine, and piperazine; Sulfur-containing alicyclic heterocyclic structures such as thietane, thiolane, and thiane; Examples of the heterocyclic ring include alicyclic heterocyclic structures containing multiple heteroatoms such as morpholine, 1,2-oxathiolane, and 1,3-oxathiolane.

[0059] Examples of the cyclic structure include a lactone structure, a cyclic carbonate structure, a sultone structure, and a structure containing a cyclic acetal. Examples of such structures include structures represented by the following formulas (H-1) to (H-10).

[0060] [ka]

[0061] In the above formula, m is an integer of 1 to 3.

[0062] Above R 8b and R 9b The ring structure having 3 to 20 ring members constituted by combining with each other together with the carbon atoms to which they are bonded is preferably an alicyclic monocyclic structure having 3 to 10 carbon atoms, an alicyclic polycyclic structure having 6 to 14 carbon atoms, or an aromatic ring structure having 8 to 20 carbon atoms. The alicyclic monocyclic structure having 3 to 10 carbon atoms and the alicyclic polycyclic structure having 6 to 14 carbon atoms may be either a saturated hydrocarbon structure or an unsaturated hydrocarbon structure. The alicyclic polycyclic structure may be either a bridged alicyclic hydrocarbon structure or a condensed alicyclic hydrocarbon structure. The condensed alicyclic hydrocarbon structure refers to a polycyclic alicyclic hydrocarbon structure constituted in such a manner that a plurality of alicyclic rings share a side (a bond between two adjacent carbon atoms).

[0063] Among the alicyclic monocyclic structures, preferred saturated hydrocarbon structures are cyclopentane, cyclohexane, cycloheptane, cyclooctane, etc., and preferred unsaturated hydrocarbon structures are cyclopentene, cyclohexene, cycloheptene, cyclooctene, cyclodecene, etc. Preferred alicyclic polycyclic structures are bridged alicyclic saturated hydrocarbon structures, such as bicyclo[2.2.1]heptane (norbornane), bicyclo[2.2.2]octane, tricyclo[3.3.1.1]heptane, etc. 3,7 ]Decane (adamantane), etc. are preferred.

[0064] Examples of the aromatic ring structure having 8 to 20 carbon atoms include indene, fluorene, and xanthene.

[0065] n4 is preferably an integer of 1 to 3, more preferably 1 or 2, and particularly preferably 1.

[0066] Compound (1) is represented by the above formula (1-2), and R f1 and R f2 are each independently a fluorine atom or a perfluoroalkyl group having 1 to 5 carbon atoms, and R 1 and R 2 is a hydrogen atom, n1 and n2 are 1, n3 is 0, and n4 is 1; X 1 and X 2 is preferably an oxygen atom. When compound (1) has this structure, the sensitivity, LWR performance, and CDU performance can be improved.

[0067] Specific examples of compound (1-1) include, but are not limited to, onium salt compounds represented by the following formulas (1-1-1) to (1-1-32) (hereinafter, the onium salt compounds represented by the following formulas (1-1-1) to (1-1-32) are also referred to as "compound (1-1-1) to compound (1-1-32)").

[0068] [ka]

[0069] [ka]

[0070] [ka]

[0071] In the above formulas (1-1-1) to (1-1-32), Z + is a radiation-sensitive onium cation.

[0072] Specific examples of compound (1-2) include, but are not limited to, the following formulas (1-2-1) to (1-2-86) (hereinafter, the onium salt compounds represented by the following formulas (1-2-1) to (1-2-86) are also referred to as "compound (1-2-1) to compound (1-2-86)").

[0073] [ka]

[0074] [ka]

[0075] [ka]

[0076] [ka]

[0077] [ka]

[0078] In the above formulas (1-2-1) to (1-2-86), Z + is a radiation-sensitive onium cation.

[0079] The compounds (1-1-1) to (1-1-32) and the compounds (1-2-1) to (1-2-86) are onium salt compounds having one specific partial structure. The compounds (1-2-80) and the compounds (1-2-83) to (1-2-86) are compounds that can be polymerized with other acrylic acid ester monomers or hydroxystyrene monomers, if necessary, to give a resin form (acid generating resin) having the specific partial structure as a part of the resin.

[0080] Examples of the onium salt compound having two specific partial structures include compounds represented by the following formulas (1-3-1) to (1-3-2).

[0081] [ka]

[0082] The content of the compound (1) in the form of a compound (the total of the compounds (1) when used in combination) is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more, and particularly preferably 0.5 parts by mass or more, relative to 100 parts by mass of the resin described below. The content is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 30 parts by mass or less. The content of the compound (1) in the form of a resin is the amount of the resin in the form of a compound replaced with an acid generating resin, and the content of the other components may be defined as the amount relative to 100 parts by mass of the acid generating resin. The content of the compound (1) is appropriately selected depending on the type of resin used, the exposure conditions and the required sensitivity, and the type and content of the radiation-sensitive acid generator described below. This allows the resist pattern to exhibit excellent sensitivity, LWR performance, and CDU performance during the formation of the resist pattern.

[0083] (Method of synthesizing compound (1)) As a method for synthesizing compound (1), a compound (1-2) (in the above formula (1-2), X 1 and X 2are oxygen atoms and n4 is 1) will be taken as an example. As shown in the following scheme, a dihydroxycarboxylic acid is first converted into an ester, and then the diol of this ester is reacted with a ketone to form an acetal. Next, the ester is hydrolyzed with an appropriate alkali (lithium hydroxide in the scheme below) to form a carboxylic acid, and finally, the target compound (1-2a) can be synthesized by esterification with a hydroxyonium salt compound.

[0084] [ka]

[0085] In the above scheme, R f1 , R f2 , R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8b , R 9b , n1, n2, n3 and Z + R has the same meaning as in formula (1) above. 101 is an alkyl group.

[0086] As a method for synthesizing compound (1), a compound (1-1) (in the above formula (1-1), X 1 and X 2 are both oxygen atoms, and R 8a and R 9a Here, an example in which both are acyl groups will be used for explanation. Typically, as shown in the scheme below, a diester is first formed between the hydroxy group of the ester obtained in the synthesis scheme of compound (1-2) and a carboxylic acid. Furthermore, a triester is formed between the hydroxy group of the diester and a carboxylic acid halide (chloride in the scheme). Next, this is hydrolyzed with an appropriate alkali (lithium hydroxide in the scheme below) to form a diester carboxylic acid, and finally, the target compound (1-1a) can be synthesized through esterification with a hydroxyonium salt compound.

[0087] [ka]

[0088] In the above scheme, R f1 , R f2 , R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , n1, n2, n3 and Z + R has the same meaning as in formula (1) above. 101 is an alkyl group. 102 and R 103 is a monovalent organic group.

[0089] Compounds (1) having other structures can be similarly synthesized by appropriately selecting the respective precursors corresponding to the anion portion and the onium cation portion.

[0090] (resin) The resin is an assembly of polymers having a structural unit (hereinafter also referred to as "structural unit (I)") containing an acid-dissociable group (hereinafter also referred to as "base resin"). The "acid-dissociable group" refers to a group that substitutes a hydrogen atom in a carboxy group, a phenolic hydroxyl group, an alcoholic hydroxyl group, a sulfo group, etc., and dissociates under the action of an acid. The radiation-sensitive resin composition has excellent pattern formability because the resin has the structural unit (I).

[0091] In addition to the structural unit (I), the base resin preferably has a structural unit (II) containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure, which will be described later, and may have other structural units other than the structural units (I) and (II). Each structural unit will be described below.

[0092] Structural Units The structural unit (I) is a structural unit containing an acid dissociable group. The structural unit (I) is not particularly limited as long as it contains an acid dissociable group, and examples thereof include a structural unit having a tertiary alkyl ester moiety, a structural unit having a structure in which 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 (3) (hereinafter also referred to as "structural unit (I-1)") is preferred.

[0093] [ka]

[0094] In the above formula (3), R 17 R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 18 R is a monovalent hydrocarbon group having 1 to 20 carbon atoms. 19 and R 20 each independently represents a monovalent chain hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a divalent alicyclic group having 3 to 20 carbon atoms constituted by combining these groups together with the carbon atoms to which they are bonded.

[0095] Above R 17 From the viewpoint of copolymerizability of the monomer that gives the structural unit (I-1), a hydrogen atom or a methyl group is preferable, and a methyl group is more preferable.

[0096] Above R 18 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.

[0097] Above R 18 ~R 20 Examples of the chain hydrocarbon group having 1 to 10 carbon atoms represented by the formula (I) include linear or branched saturated hydrocarbon groups having 1 to 10 carbon atoms, and linear or branched unsaturated hydrocarbon groups having 1 to 10 carbon atoms.

[0098] Above R 18 ~R 20 Examples of the 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. Examples of the monocyclic saturated hydrocarbon group include a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. Examples of the polycyclic cycloalkyl group include a bridged alicyclic hydrocarbon group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, and a tetracyclododecyl group. 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.

[0099] Above R 18 Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by the formula: Examples of the alkyl group include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, and an anthryl group; and aralkyl groups such as a benzyl group, a phenethyl group, and a naphthylmethyl group.

[0100] Above R 18 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.

[0101] Above R 19 and R 20 The divalent alicyclic group having 3 to 20 carbon atoms, which is formed by combining chain hydrocarbon groups or alicyclic hydrocarbon groups represented by the formula (I) with each other and the carbon atoms to which they are bonded, is not particularly limited as long as it is a group in which two hydrogen atoms are removed 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, and may be either a saturated hydrocarbon group or an unsaturated hydrocarbon group. Note that the condensed alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group formed in such a way that multiple alicyclic rings share a side (a bond between two adjacent carbon atoms).

[0102] 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.

[0103] Among these, R 18 is an alkyl group having 1 to 4 carbon atoms, and R 19 and R 20 The alicyclic structure formed by combining these together with the carbon atoms to which they are bonded is preferably a polycyclic or monocyclic cycloalkane structure.

[0104] Examples of the structural unit (I-1) include structural units represented by the following formulas (3-1) to (3-6) (hereinafter also referred to as "structural units (I-1-1) to (I-1-6)").

[0105] [ka]

[0106] In the above formulas (3-1) to (3-6), R 17 ~R 20 has the same meaning as in the above formula (3). i and j each independently represent an integer of 1 to 4. k and l each represent 0 or 1.

[0107] As i and j, 1 is preferable. 18 R is preferably a methyl group, an ethyl group, or an isopropyl group. 19 and R20 As the alkyl group, a methyl group or an ethyl group is preferable.

[0108] The base resin may contain one type of structural unit (I) or a combination of two or more types.

[0109] The content of the structural unit (I) (the total content when multiple types are included) is preferably 10 mol% or more, more preferably 20 mol% or more, even more preferably 30 mol% or more, and particularly preferably 35 mol% or more, based on the total structural units constituting the base resin. Also, it is preferably 80 mol% or less, more preferably 75 mol% or less, even more preferably 70 mol% or less, and particularly preferably 65 mol% or less. By setting the content of the structural unit (I) within the above range, the pattern formability of the radiation-sensitive resin composition can be further improved.

[0110] [Structural unit (II)] The structural unit (II) is a structural unit containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, and a sultone structure. The base resin further contains the structural unit (II), which allows the base resin to adjust its solubility in a developer, and as a result, the radiation-sensitive resin composition can improve lithography performance such as resolution. In addition, the adhesion between the resist pattern formed from the base resin and the substrate can be improved.

[0111] Examples of the structural unit (II) include structural units represented by the following formulas (T-1) to (T-10).

[0112] [ka]

[0113] In the above formula, R L1 R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L2 ~R L5are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a cyano group, a trifluoromethyl group, a methoxy group, a methoxycarbonyl group, a hydroxy group, a hydroxymethyl group, or a dimethylamino group. L4 and R L5 L may be combined with each other to form a divalent alicyclic group having 3 to 8 carbon atoms together with the carbon atom to which they are bonded. 2 is a single bond or a divalent linking group. X is an oxygen atom or a methylene group. k is an integer of 0 to 3. m is an integer of 1 to 3.

[0114] Above R L4 and R L5 Examples of the divalent alicyclic group having 3 to 8 carbon atoms formed by combining together with the carbon atom to which they are bonded include R 19 and R 20 Among divalent alicyclic groups having 3 to 20 carbon atoms constituted by combining chain hydrocarbon groups or alicyclic hydrocarbon groups represented by the following formula (I) together with the carbon atoms to which they are bonded, groups having 3 to 8 carbon atoms are exemplified. One or more hydrogen atoms on this alicyclic group may be substituted with a hydroxy group.

[0115] The above L 2 Examples of the divalent linking group represented by the formula (I) include a divalent linear or branched hydrocarbon group having 1 to 10 carbon atoms, a divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms, or a group composed of one or more of these hydrocarbon groups and at least one group selected from -CO-, -O-, -NH-, and -S-.

[0116] Of these, the structural unit (II) is preferably a structural unit containing a lactone structure, more preferably a structural unit containing a norbornane lactone structure, and even more preferably a structural unit derived from norbornane lactone-yl (meth)acrylate.

[0117] The content of the structural unit (II) is preferably 20 mol% or more, more preferably 30 mol% or more, and even more preferably 35 mol% or more, based on the total structural units constituting the base resin. Also, it is preferably 75 mol% or less, more preferably 70 mol% or less, and even more preferably 65 mol% or less. By setting the content of the structural unit (II) within the above range, the radiation-sensitive resin composition can further improve the lithography performance such as resolution and the adhesion of the formed resist pattern to the substrate.

[0118] [Structural unit (III)] The base resin may have other structural units in addition to the structural units (I) and (II). Examples of the other structural units include a structural unit (III) containing a polar group (excluding the structural unit (II)). The base resin may further have the structural unit (III) to adjust the solubility in a developer, thereby improving the lithography performance of the radiation-sensitive resin composition, such as the resolution. Examples of the polar group include a hydroxy group, a carboxy group, a cyano group, a nitro group, and a sulfonamide group. Among these, a hydroxy group and a carboxy group are preferred, and a hydroxy group is more preferred.

[0119] Examples of the structural unit (III) include structural units represented by the following formula:

[0120] [ka]

[0121] In the above formula, R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0122] When the base resin has the structural unit (III) having the polar group, the content of the structural unit (III) is preferably 5 mol% or more, more preferably 8 mol% or more, and even more preferably 10 mol% or more, based on the total structural units constituting the base resin. Also, it is preferably 40 mol% or less, more preferably 35 mol% or less, and even more preferably 30 mol% or less. By setting the content of the structural unit (III) within the above range, the lithography performance such as the resolution of the radiation-sensitive resin composition can be further improved.

[0123] Structural Units (IV) The base resin optionally has, as other structural units, a structural unit derived from hydroxystyrene or a structural unit having a phenolic hydroxyl group (hereinafter, both of them are also referred to as "structural unit (IV)") in addition to the structural unit (III) having the polar group. The structural unit (IV) contributes to improving the etching resistance and the difference in developer solubility (dissolution contrast) between the exposed and unexposed areas. In particular, it 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. In this case, it is preferable that the resin has the structural unit (I) together with the structural unit (IV).

[0124] In this case, it is preferable to carry out polymerization in a state in which the phenolic hydroxyl group is protected by a protecting group such as an alkali-dissociable group, and then to obtain the structural unit (IV) by deprotection through hydrolysis. The structural unit that gives the structural unit (IV) upon hydrolysis is preferably represented by the following formula (4-1) or (4-2).

[0125] [ka]

[0126] In the above formulas (4-1) and (4-2), 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.12 As the monovalent hydrocarbon group having 1 to 20 carbon atoms, R 8 Examples of the alkoxy group include a methoxy group, an ethoxy group, and a tert-butoxy group.

[0127] 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.

[0128] In the case of a resin for exposure to radiation having a wavelength of 50 nm or less, the content of the structural unit (IV) is preferably 10 mol % or more, more preferably 20 mol % or more, based on the total structural units constituting the resin, and is preferably 70 mol % or less, more preferably 60 mol % or less.

[0129] (Method of synthesizing base resin) The base resin can be synthesized, for example, by polymerizing monomers that provide each structural unit in an appropriate solvent using a radical polymerization initiator or the like.

[0130] 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.

[0131] Examples of the solvent used in the polymerization include Alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane; Cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, and norbornane; Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and cumene; Halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, and chlorobenzene; Saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate, and methyl propionate; Ketones such as acetone, methyl ethyl ketone, 4-methyl-2-pentanone, and 2-heptanone; Ethers such as tetrahydrofuran, dimethoxyethanes, and diethoxyethanes; Examples of the solvent include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 4-methyl-2-pentanol, etc. These solvents used in the polymerization may be used alone or in combination of two or more kinds.

[0132] The reaction temperature in the polymerization 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.

[0133] The molecular weight of the base resin 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 base resin is less than the lower limit, the heat resistance of the resulting resist film may be reduced. If the Mw of the base resin is greater than the upper limit, the developability of the resist film may be reduced.

[0134] The ratio (Mw / Mn) of Mw to the polystyrene-equivalent number average molecular weight (Mn) of the base resin as determined by GPC is usually 1 or more and 5 or less, preferably 1 or more and 3 or less, and more preferably 1 or more and 2 or less.

[0135] In this specification, the Mw and Mn of the resin are values ​​measured by gel permeation chromatography (GPC) under the following conditions.

[0136] 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

[0137] The content of the base resin is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass or more, based on the total solid content of the radiation-sensitive resin composition.

[0138] (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 water repellency of the surface of the resist film during immersion exposure can be increased.

[0139] The high fluorine content resin preferably has, for example, a structural unit represented by the following formula (5) (hereinafter also referred to as "structural unit (V)"), and may have the structural unit (I) or the structural unit (II) in the above base resin, as necessary.

[0140] [ka]

[0141] In the above formula (5), R 13is a hydrogen atom, a methyl group, or a trifluoromethyl group. L is a single bond, an oxygen atom, a sulfur atom, -COO-, -SO2ONH-, -CONH-, or -OCONH-. 14 represents 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.

[0142] Above R 13 From the viewpoint of copolymerizability of the monomer that gives the structural unit (V), a hydrogen atom or a methyl group is preferable, and a methyl group is more preferable.

[0143] Above G L As the group, from the viewpoint of copolymerizability of the monomer that gives the structural unit (V), a single bond and -COO- are preferable, and -COO- is more preferable.

[0144] Above R 14 Examples of the monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) 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.

[0145] Above R 14 Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the following formula 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.

[0146] 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.

[0147] When the high fluorine content resin has the structural unit (V), the content of the structural unit (V) is preferably 30 mol% or more, more preferably 40 mol% or more, even more preferably 45 mol% or more, and particularly preferably 50 mol% or more, based on the total structural units constituting the high fluorine content resin. Also, it is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less. By setting the content of the structural unit (V) 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 the fluorine atoms in the surface layer of the resist film can be further promoted, and as a result, the water repellency of the resist film during immersion exposure can be further improved.

[0148] The high fluorine content resin may have a fluorine atom-containing structural unit represented by the following formula (f-2) (hereinafter also referred to as structural unit (VI)) in addition to or instead of the structural unit (V). By having the structural unit (f-2), the high fluorine content resin has improved solubility in an alkaline developer, and the occurrence of development defects can be suppressed.

[0149] [ka]

[0150] The structural unit (VI) is roughly classified into two types: (x) a type having an alkali-soluble group, and (y) a type having a group that dissociates under the action of an alkali to increase the solubility in an alkali developer (hereinafter, also referred to simply 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. ddrepresents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. s represents an integer of 1 to 3.

[0151] When the structural unit (VI) has an alkali-soluble group (x), R F is a hydrogen atom, and A 1 is an oxygen atom, -COO-* or -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 If 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. E is a single bond or a divalent organic group having 1 to 20 carbon atoms. When s is 2 or 3, multiple R E , W 1 , A 1 and R F may be the same or different. When the structural unit (VI) has an alkali-soluble group (x), it is possible to increase the affinity for an alkali developer and suppress development defects. As the structural unit (VI) having an alkali-soluble group (x), A 1 is an oxygen atom and W 1 It is particularly preferred that R is a 1,1,1,3,3,3-hexafluoro-2,2-methanediyl group.

[0152] When the structural unit (VI) 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 1or R F A 1 A has a fluorine atom on the carbon atom bonded to or adjacent to the carbon atom. 1 If 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 F may be the same or different. When the structural unit (VI) has an alkali dissociable group (y), the surface of the resist film changes from hydrophobic to hydrophilic in the 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 (VI) 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.

[0153] R C From the viewpoint of copolymerizability of the monomer that gives the structural unit (VI), etc., a hydrogen atom or a methyl group is preferable, and a methyl group is more preferable.

[0154] 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.

[0155] When the high fluorine content resin has the structural unit (VI), the content of the structural unit (VI) is preferably 40 mol% or more, more preferably 50 mol% or more, and even more preferably 60 mol% or more, based on the total structural units constituting the high fluorine content resin. Also, it is preferably 95 mol% or less, more preferably 90 mol% or less, and even more preferably 85 mol% or less. By setting the content of the structural unit (VI) within the above range, the water repellency of the resist film during immersion exposure can be further improved.

[0156] [Other structural units] The high fluorine content resin may contain a structural unit having an alicyclic structure represented by the following formula (6) as a structural unit other than the structural units listed above. [ka] (In the above formula (6), R 1α R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. 2α is a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0157] In the above formula (6), R 2α As the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (1), 8 A monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, represented by the following formula, can be suitably used.

[0158] When the high-fluorine-content resin contains the structural unit having the alicyclic structure, the content of the structural unit having the alicyclic structure is preferably 10 mol % or more, more preferably 20 mol % or more, and even more preferably 30 mol % or more, based on the total structural units constituting the high-fluorine-content resin, and is preferably 70 mol % or less, more preferably 60 mol % or less, and even more preferably 50 mol % or less.

[0159] The Mw of the high fluorine content resin is preferably 1,000 or more, more preferably 2,000 or more, even more preferably 3,000 or more, and particularly preferably 5,000 or more. Also, it is preferably 50,000 or less, more preferably 30,000 or less, even more preferably 20,000 or less, and particularly preferably 15,000 or less.

[0160] The Mw / Mn of the high fluorine content resin is usually 1 or more, and more preferably 1.1 or more, and usually 5 or less, and preferably 3 or less, more preferably 2 or less, and even more preferably 1.9 or less.

[0161] The content of the high fluorine content resin is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1 part by mass or more, and particularly preferably 1.5 parts by mass or more, relative to 100 parts by mass of the base resin, and is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 8 parts by mass or less, and particularly preferably 5 parts by mass or less.

[0162] 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.

[0163] (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.

[0164] (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 compound (1) upon exposure, and has the effect of suppressing undesirable chemical reactions in non-exposed regions. In addition, the storage stability of the resulting radiation-sensitive resin composition is improved. Furthermore, the resolution of the resist pattern is further improved, and changes in the line width of the resist pattern due to fluctuations in the delay time from exposure to development can be suppressed, resulting in a radiation-sensitive resin composition with excellent process stability.

[0165] Examples of the acid diffusion controller include a compound represented by the following formula (7) (hereinafter also referred to as "nitrogen-containing compound (I)"), a compound having two nitrogen atoms in the same molecule (hereinafter also referred to as "nitrogen-containing compound (II)"), a compound having three nitrogen atoms (hereinafter also referred to as "nitrogen-containing compound (III)"), an amide group-containing compound, a urea compound, and a nitrogen-containing heterocyclic compound.

[0166] [ka]

[0167] In the above formula (7), R 22 , R 23 and R 24 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group.

[0168] Examples of the nitrogen-containing compound (I) include monoalkylamines such as n-hexylamine; dialkylamines such as di-n-butylamine; trialkylamines such as triethylamine; and aromatic amines such as aniline.

[0169] Examples of the nitrogen-containing compound (II) include ethylenediamine and N,N,N',N'-tetramethylethylenediamine.

[0170] Examples of the nitrogen-containing compound (III) include polyamine compounds such as polyethyleneimine and polyallylamine; polymers such as dimethylaminoethylacrylamide; and the like.

[0171] Examples of the amide group-containing compound include formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, benzamide, pyrrolidone, and N-methylpyrrolidone.

[0172] Examples of the urea compound include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, and tributylthiourea.

[0173] Examples of the nitrogen-containing heterocyclic compound include pyridines such as pyridine and 2-methylpyridine; morpholines such as N-propylmorpholine and N-(undecylcarbonyloxyethyl)morpholine; pyrazine, pyrazole, and the like.

[0174] In addition, as the nitrogen-containing organic compound, a compound having an acid dissociable group can also be used.As the nitrogen-containing organic compound having an acid dissociable group, for example, Nt-butoxycarbonylpiperidine, Nt-butoxycarbonylimidazole, Nt-butoxycarbonylbenzimidazole, Nt-butoxycarbonyl-2-phenylbenzimidazole, N-(t-butoxycarbonyl)di-n-octylamine, N-(t-butoxycarbonyl)diethanolamine, N-(t-butoxycarbonyl)dicyclohexylamine, N-(t-butoxycarbonyl)diphenylamine, Nt-butoxycarbonyl-4-hydroxypiperidine, Nt-amyloxycarbonyl-4-hydroxypiperidine, etc. can be mentioned.

[0175] Also, a radiation-sensitive weak acid generator that generates a weak acid upon exposure can be suitably used as the acid diffusion control agent. The acid generated by the radiation-sensitive acid generator is a weak acid that does not induce dissociation of the acid-dissociable group in the resin under conditions that dissociate the acid-dissociable group. In this specification, the "dissociation" of the acid-dissociable group refers to dissociation upon post-exposure baking at 110°C for 60 seconds.

[0176] Examples of the radiation-sensitive weak acid generator include onium salt compounds that decompose upon exposure to light and lose their ability to control acid diffusion. Examples of the onium salt compound include sulfonium salt compounds represented by the following formula (8-1) and iodonium salt compounds represented by the following formula (8-2).

[0177] [ka]

[0178] In the above formula (8-1) and formula (8-2), J + is a sulfonium cation, and U + is the iodonium cation. + Examples of the sulfonium cation represented by the formula (X-1) to (X-3) include the sulfonium cations represented by the formula (X-1) to (X-3), and U + Examples of the iodonium cation represented by the formula (X-4) to (X-5) include the iodonium cation represented by the formula (X-4) to (X-5). - and Q - are each independently OH - , R α -COO - , R α -SO3 - It is an anion represented by R α R is an alkyl group, an aryl group, or an aralkyl group. α A hydrogen atom in the aromatic ring of the aryl group or aralkyl group represented by the following formula may be substituted with a hydroxy group, a fluorine atom-substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.

[0179] Examples of the radiation-sensitive weak acid generator include compounds represented by the following formula:

[0180] [ka]

[0181] Of these, the radiation-sensitive weak acid generator is preferably a sulfonium salt, more preferably a triarylsulfonium salt, and even more preferably triphenylsulfonium salicylate or triphenylsulfonium 10-camphorsulfonate.

[0182] The content of the acid diffusion controller is preferably 3 parts by mass or more, more preferably 4 parts by mass or more, and even more preferably 5 parts by mass or more, relative to 100 parts by mass of the total of the radiation-sensitive acid generators, and is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, and even more preferably 110 parts by mass or less.

[0183] By setting the content of the acid diffusion controller within the above range, the lithography performance of the radiation-sensitive resin composition can be further improved. The radiation-sensitive resin composition may contain one or more types of acid diffusion controller.

[0184] (solvent) The radiation-sensitive resin composition according to the present embodiment contains a solvent. The solvent is not particularly limited as long as it is capable of dissolving or dispersing at least the compound (1) and the resin, as well as the radiation-sensitive acid generator and other components that are optionally contained therein.

[0185] Examples of the solvent include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

[0186] 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-mentioned polyhydric alcohol solvents.

[0187] 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.

[0188] 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.

[0189] 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.

[0190] 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 solvent include polyvalent carboxylate diester solvents such as propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoacetate, ethyl lactate, and diethyl phthalate.

[0191] 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.

[0192] 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.

[0193] (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 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.

[0194] (Crosslinking agent) The crosslinking agent is a compound having two or more functional groups, which causes a crosslinking reaction in the resin component by an acid catalysis in the baking step after the floodwise exposure step, thereby increasing the molecular weight of the resin 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.

[0195] (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.

[0196] Examples of the lactone compound include γ-butyrolactone, valerolactone, mevalonic lactone, and norbornane lactone.

[0197] Examples of the carbonate compound include propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, and the like.

[0198] The nitrile compound may, for example, be succinonitrile.

[0199] An example of the polyhydric alcohol is glycerin.

[0200] The content of the uneven distribution promoter is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, and even more preferably 25 parts by mass or more, based on 100 parts by mass of the total amount of the resin in the radiation-sensitive resin composition. Also, the content is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, even more preferably 100 parts by mass or less, and particularly preferably 80 parts by mass or less. The radiation-sensitive resin composition may contain one or more kinds of uneven distribution promoters.

[0201] (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.

[0202] (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.

[0203] 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.

[0204] (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.

[0205] 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.

[0206] <Method for preparing radiation-sensitive resin composition> The radiation-sensitive resin composition can be prepared, for example, by mixing compound (A), a resin, a radiation-sensitive acid generator, and if necessary, a high-fluorine content resin, and a solvent 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 to 0.2 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.

[0207] <Pattern formation method> A pattern forming method according to one embodiment of the present invention includes the steps of: a step (1) of directly or indirectly applying the radiation-sensitive resin composition onto a substrate to form a resist film (hereinafter also referred to as a "resist film forming step"); a step (2) of exposing the resist film to light (hereinafter also referred to as an "exposure step"); and a step (3) of developing the exposed resist film (hereinafter also referred to as the "developing step").

[0208] According to the above-mentioned method for forming a resist pattern, since the above-mentioned radiation-sensitive resin composition having excellent sensitivity, LWR performance, and CDU performance in the exposure step is used, a high-quality resist pattern can be formed. Each step will be described below.

[0209] [Resist film formation process] In this step (step (1) above), a resist film is formed from the radiation-sensitive resin composition. 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.

[0210] 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 liquid may be provided on the formed resist film in order to prevent direct contact between the immersion liquid 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.

[0211] 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 above structural units (I) and (IV) as the base resin in the composition.

[0212] [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 electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV (extreme ultraviolet light), X-rays, and gamma rays; and charged particle beams such as electron beams and alpha rays, depending on the line width of the desired pattern. Among these, far ultraviolet light, electron beams, and EUV are preferred, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), electron beams, and EUV are more preferred, and electron beams and EUV with wavelengths of 50 nm or less, which are positioned as next-generation exposure technologies, are even more preferred.

[0213] When the exposure is performed by immersion exposure, the immersion liquid used may be, for example, water or a fluorine-based inert liquid. The immersion liquid 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, but when the exposure light source is an ArF excimer laser light (wavelength 193 nm), in addition to the above-mentioned viewpoint, water is preferably used from the viewpoint of ease of availability and ease of handling. When water is used, a small proportion of an additive that reduces the surface tension of water and increases the surfactant power may be added. It is preferable that this additive 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.

[0214] After the exposure, it is preferable to perform post-exposure baking (PEB) to promote dissociation of acid-dissociable groups of resins and the like by the acid generated from the radiation-sensitive acid generator by exposure in the exposed parts of the resist film. This PEB causes a difference in solubility in a developer between the exposed parts and the unexposed parts. The PEB temperature is usually 50°C to 180°C, and preferably 80°C to 130°C. The PEB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds.

[0215] [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.

[0216] 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.

[0217] 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 an organic solvent. 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, ether solvents, ester solvents, and ketone solvents are preferred. As the ether solvent, glycol ether solvents are preferred, and ethylene glycol monomethyl ether and propylene glycol monomethyl ether are more preferred. As the ester solvent, acetate ester solvents are preferred, and n-butyl acetate and amyl acetate are more preferred. As the ketone solvent, chain ketones are preferred, and 2-heptanone is more preferred. The content of the organic solvent in the developer is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more. Examples of components other than the organic solvent in the developer include water and silicone oil.

[0218] As described above, the developer may be either an alkaline developer or an organic solvent developer, and can be appropriately selected depending on whether the desired pattern is a positive type or a negative type.

[0219] Examples of development methods include a method in which a substrate is immersed in a tank filled with a developer for a certain period of time (dip method), a method in which a 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 a developer is sprayed onto the substrate surface (spray method), and a method in which a developer is continuously dispensed while a developer dispensing nozzle is scanned at a constant speed onto a substrate rotating at a constant speed (dynamic dispense method). EXAMPLES

[0220] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Measurement methods for various physical properties are shown below.

[0221] [Weight average molecular weight (Mw) and number average molecular weight (Mn)] The Mw and Mn of the resin (including the acid generating resin) were measured under the conditions described above. The dispersity (Mw / Mn) was calculated from the measurement results of Mw and Mn.

[0222] [ 13 C-NMR analysis] Resin 13 C-NMR analysis was performed using a nuclear magnetic resonance spectrometer (JNM-Delta400 manufactured by JEOL Ltd.).

[0223] <Synthesis of compound (1)> [Synthesis Example 1] (Synthesis of compound (B-1)) Compound (B-1) was synthesized according to the following synthesis scheme.

[0224] [ka]

[0225] 20.0 mmol of glyceric acid, 1.00 mmol of concentrated sulfuric acid, and 50 g of methanol were added to a reaction vessel and stirred at 100°C for 12 hours. Thereafter, a saturated aqueous solution of sodium bicarbonate was added to stop the reaction, and then ethyl acetate was added for extraction and the organic layer was separated. The obtained organic layer was washed with a saturated aqueous solution of sodium chloride and then with water. After drying with sodium sulfate, the solvent was distilled off, and the ester was obtained in good yield by purifying by column chromatography.

[0226] 20.0 mmol of 2-adamantanone, 1.00 mmol of concentrated sulfuric acid, and 50 g of toluene were added to the above ester, and the mixture was stirred at 150° C. for 4 hours. Thereafter, a saturated aqueous solution of sodium bicarbonate was added to terminate the reaction, and then ethyl acetate was added for extraction and the organic layer was separated. The organic layer obtained was washed with a saturated aqueous solution of sodium chloride and then with water. After drying with sodium sulfate, the solvent was distilled off, and the product was purified by column chromatography to obtain an acetal product in good yield.

[0227] A mixture of acetonitrile and water (1:1 (mass ratio)) was added to the above acetal product to prepare a 1M solution, and then 20.0 mmol of lithium hydroxide was added and reacted at room temperature for 4 hours. Thereafter, 1M hydrochloric acid was added to make the system acidic, and methylene chloride was added for extraction and separation of the organic layer. The resulting organic layer was washed with a saturated aqueous sodium chloride solution and then with water. After drying with sodium sulfate, the solvent was distilled off to obtain a carboxylic acid product in good yield.

[0228] The carboxylic acid was added with 20.0 mmol of triphenylsulfonium 1,1-difluoro-2-hydroxymethane-1-sulfonate, 30.0 mmol of dicyclohexylcarbodiimide, and 50 g of methylene chloride, and reacted at room temperature for 5 hours. After that, water was added for dilution, and methylene chloride was added for extraction, and the organic layer was separated. The organic layer obtained was washed with a saturated aqueous sodium chloride solution and then with water. After drying with sodium sulfate, the solvent was distilled off, and the compound (B-1) represented by the above formula (B-1) was obtained in good yield by purifying the compound by column chromatography.

[0229] [Synthesis Examples 2-22] (Synthesis of compounds (B-2) to (B-22)) Compounds (1) represented by the following formulae (B-2) to (B-22) were synthesized in the same manner as in Synthesis Example 1, except that the raw materials and precursors were appropriately changed. The compounds represented by the following formulae (B-21) to (B-22) were used to synthesize an acid-generating resin.

[0230] [ka]

[0231] [Synthesis Example 23] (Synthesis of compound (B-23)) Using the above-mentioned ester as a raw material, compound (B-23) was synthesized according to the following synthesis scheme.

[0232] [ka]

[0233] The above ester (20.0 mmol), pivalic acid (20.0 mmol), dicyclohexylcarbodiimide (20.0 mmol), and methylene chloride (50 g) were added to a reaction vessel and reacted at room temperature for 5 hours. After that, water was added for dilution, and methylene chloride was added for extraction and the organic layer was separated. The obtained organic layer was washed with a saturated aqueous sodium chloride solution and then with water. After drying with sodium sulfate, the solvent was distilled off and the diester was purified by column chromatography to obtain a good yield.

[0234] The diester was added with 20.0 mmol of 1-adamantanecarbonyl chloride, 20.0 mmol of triethylamine, and 50 g of acetonitrile, and stirred at room temperature for 12 hours. After that, a saturated aqueous solution of ammonium chloride was added to stop the reaction, and then ethyl acetate was added for extraction and the organic layer was separated. The organic layer obtained was washed with a saturated aqueous solution of sodium chloride and then with water. After drying with sodium sulfate, the solvent was distilled off, and the triester was purified by column chromatography to obtain a good yield.

[0235] The triester was added with a mixture of acetonitrile and water (1:1 (mass ratio)) to give a 1M solution, and then 15.0 mmol of lithium hydroxide was added and reacted at room temperature for 1 hour. Then, 1M hydrochloric acid was added to make the system acidic, and methylene chloride was added for extraction and separation of the organic layer. The resulting organic layer was washed with a saturated aqueous sodium chloride solution and then with water. After drying with sodium sulfate, the solvent was distilled off to give a diester carboxylic acid in good yield.

[0236] The diester carboxylic acid was added with 15.0 mmol of triphenylsulfonium 1,1-difluoro-2-hydroxymethane-1-sulfonate, 25.0 mmol of dicyclohexylcarbodiimide, and 50 g of methylene chloride, and reacted at room temperature for 5 hours. After that, water was added for dilution, and methylene chloride was added for extraction, and the organic layer was separated. The obtained organic layer was washed with a saturated aqueous sodium chloride solution and then with water. After drying with sodium sulfate, the solvent was distilled off, and the compound (B-23) represented by the above formula (B-23) was obtained in good yield by purifying the compound by column chromatography.

[0237] [Synthesis Examples 24-31] (Synthesis of compounds (B-24) to (B-31)) Compounds (1) represented by the following formulae (B-24) to (B-31) were synthesized in the same manner as in Synthesis Example 23, except that the raw materials and precursors were appropriately changed.

[0238] [ka]

[0239] [Radiation-sensitive acid generators other than compounds (B-1) to (B-31)] b-1 to b-15: Compounds represented by the following formulas (b-1) to (b-15) (hereinafter, the compounds represented by the formulas (b-1) to (b-15) may be referred to as "compound (b-1)" to "compound (b-15)", respectively.)

[0240] [ka]

[0241] <Synthesis of resin and high fluorine content resin> The monomers used in the synthesis of each resin and high-fluorine content resin 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 %.

[0242] [ka]

[0243] [Synthesis Example 32] (Synthesis of Resin (A-1)) Monomer (M-1), monomer (M-2) and monomer (M-13) were dissolved in 2-butanone (200 parts by mass) so that the molar ratio was 40 / 15 / 45 (mol%), and AIBN (azobisisobutyronitrile) (3 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 a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C, and the monomer solution was dropped 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 was washed twice with methanol, filtered, and dried at 50°C for 24 hours to obtain a white powdery resin (A-1) (yield: 83%). The Mw of the resin (A-1) was 8,800, and the Mw / Mn was 1.50. 13 As a result of C-NMR analysis, the contents of the structural units derived from (M-1), (M-2) and (M-13) were 41.3 mol %, 13.8 mol % and 44.9 mol %, respectively.

[0244] [Synthesis Examples 33-42] (Synthesis of Resin (A-2) to Resin (A-11)) Resins (A-2) to (A-11) were synthesized in the same manner as in Synthesis Example 1, except that the types and blending ratios of monomers shown in Table 1 were used. The content ratio (mol %) of each structural unit, yield (%), and physical properties (Mw and Mw / Mn) of the obtained resins are also shown in Table 1. In Table 1, "-" indicates that the corresponding monomer was not used (the same applies to the following tables).

[0245] [Table 1]

[0246] [Synthesis Example 43] (Synthesis of acid generating resin (B-32)) Monomer (M-1), monomer (M-2), monomer (M-5) and monomer (B-22) were dissolved in 2-butanone (200 parts by mass) so that the molar ratio was 40 / 10 / 45 / 5 (mol%), and AIBN (azobisisobutyronitrile) (6 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 a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C, and the monomer solution was dropped 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 hexane (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane, filtered, and dried at 50°C for 24 hours to obtain a white powdery resin (A-12) (yield: 72%). The acid generating resin (B-32) had an Mw of 5,600 and an Mw / Mn of 1.61. 13 As a result of C-NMR analysis, the contents of the structural units derived from (M-1), (M-2), (M-5) and (B-22) were 41.3 mol %, 9.1 mol %, 45.6 mol % and 4.0 mol %, respectively.

[0247] [Synthesis Examples 44-45] (Synthesis of Acid-Generating Resin (B-33) to Acid-Generating Resin (B-34)) Acid generating resin (B-33) to acid generating resin (B-34) were synthesized in the same manner as in Synthesis Example 12, except that the types and blending ratios of monomers shown in Table 2 were used. The content ratio (mol %) of each structural unit, the yield (%) and physical properties (Mw and Mw / Mn) of the obtained acid generating resins are also shown in Table 2.

[0248] [Table 2]

[0249] [Synthesis Example 46] (Synthesis of Resin (A-12)) Monomer (M-1) and monomer (M-18) were dissolved in 1-methoxy-2-propanol (200 parts by mass) so that the molar ratio was 50 / 50 (mol%), and AIBN (5 mol%) was added as an initiator to prepare a monomer solution. 1-Methoxy-2-propanol (100 parts by mass) was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C, and the monomer solution was dropped 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 hexane (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane, filtered off, and dissolved in 1-methoxy-2-propanol (300 parts by mass). Next, methanol (500 parts by mass), triethylamine (50 parts by mass) and ultrapure water (10 parts by mass) were added, and the hydrolysis reaction was carried out at 70°C for 6 hours while stirring. After the reaction was completed, the remaining solvent was distilled off, and the obtained solid was dissolved in acetone (100 parts by mass) and dropped into water (500 parts by mass) to coagulate the resin. The obtained solid was filtered and dried at 50°C for 13 hours to obtain a white powdery resin (A-12) (yield: 79%). The Mw of the resin (A-15) was 5,200, and the Mw / Mn was 1.60. In addition, as a result of 13C-NMR analysis, the content ratios of each structural unit derived from (M-1) and (M-18) were 51.3 mol% and 48.7 mol%, respectively.

[0250] [Synthesis Examples 47-51] (Synthesis of Resin (A-13) to Resin (A-15) and Acid-Generating Resin (B-35) to Acid-Generating Resin (B-36)) Resins (A-13) to (A-15) and acid-generating resins (B-35) to (B-36) were synthesized in the same manner as in Synthesis Example 46, except that the types and blending ratios of monomers shown in Table 3 were used. The content ratios (mol%) of each structural unit, yields (%) and physical properties (Mw and Mw / Mn) of the obtained resins and acid-generating resins are also shown in Table 3.

[0251] [Table 3]

[0252] [Synthesis Example 52] (Synthesis of high fluorine content resin (E-1)) Monomer (M-1) and monomer (M-20) were dissolved in 2-butanone (200 parts by mass) so that the molar ratio was 20 / 80 (mol%), and AIBN (4 mol%) was added as an initiator to prepare a monomer solution. 2-butanone (100 parts by mass) was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C, and the monomer solution was added dropwise over 3 hours while stirring. The start of the drop marked 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 solvent was replaced with acetonitrile (400 parts by mass), and then hexane (100 parts by mass) was added and stirred, and the acetonitrile layer was collected. This operation was repeated three times. The solvent was replaced with propylene glycol monomethyl ether acetate to obtain a solution of high fluorine content resin (E-1) (yield: 69%). The high fluorine content resin (E-1) had an Mw of 6,000 and an Mw / Mn ratio of 1.62. 13 As a result of C-NMR analysis, the contents of the structural units derived from (M-1) and (M-20) were 19.9 mol % and 80.1 mol %, respectively.

[0253] [Synthesis Examples 53-56] (Synthesis of high fluorine content resin (E-2) to high fluorine content resin (E-5)) High fluorine content resin (E-2) to high fluorine content resin (E-5) were synthesized in the same manner as in Synthesis Example 52, except that the types and blending ratios of monomers shown in the following Table 3 were used. The content ratio (mol %) of each structural unit, yield (%) and physical properties (Mw and Mw / Mn) of the obtained high fluorine content resins are also shown in the following Table 4.

[0254] [Table 4]

[0255] [[C] Acid diffusion control agent] C-1 to C-5: Compounds represented by the following formulas (C-1) to (C-5)

[0256] [ka]

[0257] [[D] Solvent] D-1: Propylene glycol monomethyl ether acetate D-2: Propylene glycol monomethyl ether D-3: γ-butyrolactone D-4: Ethyl lactate

[0258] [Preparation of positive-type radiation-sensitive resin composition for ArF exposure] [Example 1] A radiation-sensitive resin composition (J-1) was prepared by mixing 100 parts by mass of (A-1) as the resin [A], 12.0 parts by mass of (B-1) as the compound (1), 3.0 parts by mass of (C-1) as the acid diffusion controller, 3.0 parts by mass (solids content) of (E) as the high fluorine content resin, and 3,230 parts by mass of a mixed solvent of (D-1) / (D-2) / (D-3) as the solvent, and filtering the mixture through a membrane filter having a pore size of 0.2 μm.

[0259] [Examples 2 to 57 and Comparative Examples 1 to 15] Except for using the components of the types and contents shown in Table 5 below, the radiation-sensitive resin compositions (J-2) to (J-57) and (CJ-1) to (CJ-15) were prepared in the same manner as in Example 1.

[0260] [Table 5]

[0261] <Formation of Resist Pattern Using Positive-Type Radiation-Sensitive Resin Composition for ArF Exposure> On a 12-inch silicon wafer, using a spin coater ("CLEAN TRACK ACT12" of Tokyo Electron Limited), a composition for forming an underlying antireflection film ("ARC66" of Brewer Science, Inc.) was applied, and then heated at 205°C for 60 seconds to form an underlying antireflection film with an average thickness of 100 nm. On this underlying antireflection film, the positive-type radiation-sensitive resin composition for ArF exposure prepared above was applied using the above spin coater, and PB (pre-bake) was performed at 100°C for 60 seconds. Then, by cooling at 23°C for 30 seconds, a resist film with an average thickness of 90 nm was formed. Next, for this resist film, using an ArF excimer laser immersion exposure apparatus ("TWINSCAN XT-1900i" of ASML), under the optical conditions of NA = 1.35 and Dipole (σ = 0.9 / 0.7), it was exposed through a mask pattern of 40 nm line and space. After exposure, PEB (post-exposure bake) was performed at 100°C for 60 seconds. Then, the resist film was alkali-developed using a 2.38 mass% aqueous TMAH solution as an alkali developer, washed with water after development, and further dried to form a positive-type resist pattern (40 nm line and space pattern).

[0262] <Evaluation> Regarding the resist pattern formed using the above positive-type radiation-sensitive resin composition for ArF exposure, the sensitivity and LWR performance were evaluated according to the following methods. The results are shown in Table 6 below. For the length measurement of the resist pattern, a scanning electron microscope ("CG-5000" of Hitachi High-Technologies Corporation) was used.

[0263] [sensitivity] In forming a resist pattern using the positive-tone radiation-sensitive resin composition for ArF exposure, the exposure dose required to form a 40 nm line and space pattern was determined as the optimum exposure dose, and this optimum exposure dose was determined as the sensitivity (mJ / cm2). 2 The following are considered "good" and 25mJ / cm 2 If it exceeded this, it was rated as "poor".

[0264] [LWR performance] A 40 nm line and space resist pattern was formed by irradiating the substrate with the optimum exposure dose determined in the above sensitivity evaluation. The formed resist pattern was observed from above the pattern using the above scanning electron microscope. The line width variation was measured at a total of 500 points, and a 3 sigma value was calculated from the distribution of the measured values, and this 3 sigma value was taken as the LWR (nm). The smaller the LWR value, the smaller the line roughness and the better the result. LWR performance was evaluated as "good" when it was 3.0 nm or less, and "poor" when it exceeded 3.0 nm.

[0265] [Table 6]

[0266] As is clear from the results in Table 6, the radiation-sensitive resin compositions of the Examples had good sensitivity and LWR performance when used for ArF exposure, whereas the Comparative Examples had inferior properties compared to the Examples. Therefore, when the radiation-sensitive resin compositions of the Examples are used for ArF exposure, resist patterns with high sensitivity and good LWR performance can be formed.

[0267] [Preparation of positive-type radiation-sensitive resin composition for extreme ultraviolet (EUV) exposure] [Example 58] 100 parts by mass of (A-12) as a resin, 15.0 parts by mass of (B-7) as a compound (1), 4.0 parts by mass of (C-2) as an acid diffusion control agent, 3.0 parts by mass (solid content) of (E-5) as a high fluorine content resin, and 6,110 parts by mass of a mixed solvent of (D-1) / (D-4) as a solvent were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive resin composition (J-58).

[0268] [Examples 59 to 70 and Comparative Examples 16 to 19] Radiation-sensitive resin compositions (J-59) to (J-70) and (CJ-16) to (CJ-19) were prepared in the same manner as in Example 58, except that the components of the types and contents shown in Table 7 below were used.

[0269] [Table 7]

[0270] <Formation of a resist pattern using a positive-type radiation-sensitive resin composition for EUV lithography> A composition for forming a lower anti-reflective coating ("ARC66" from Brewer Science) was applied onto a 12-inch silicon wafer using a spin coater ("CLEAN TRACK ACT12" from Tokyo Electron Co., Ltd.), and then heated at 205°C for 60 seconds to form a lower anti-reflective coating with an average thickness of 105 nm. The positive-type radiation-sensitive resin composition for EUV exposure prepared above was applied onto this lower anti-reflective coating using the spin coater, and PB was performed at 130°C for 60 seconds. Thereafter, a resist film with an average thickness of 55 nm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed to light using an EUV exposure device ("NXE3300" from ASML) with NA=0.33, illumination conditions: Conventional s=0.89, and mask: imecDEFECT32FFR02. After exposure, PEB was performed at 120°C for 60 seconds. Thereafter, the resist film was subjected to alkaline development using a 2.38 mass % aqueous solution of TMAH as an alkaline developer, and after development, it was washed with water and further dried to form a positive resist pattern (32 nm line and space pattern).

[0271] <Evaluation> The sensitivity and LWR performance of the resist patterns formed using the positive radiation-sensitive resin composition for EUV exposure were evaluated according to the following methods. The results are shown in Table 8. The resist patterns were measured using a scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000").

[0272] [sensitivity] In forming a resist pattern using the positive-type radiation-sensitive resin composition for EUV exposure, the exposure amount for forming a 32 nm line and space pattern was defined as the optimal exposure amount, and this optimal exposure amount was determined as the sensitivity (mJ / cm 2 The sensitivity was 30 mJ / cm 2 The following are considered "good": 30mJ / cm 2 If it exceeded this, it was rated as "poor".

[0273] [LWR performance] A resist pattern was formed by adjusting the mask size so that the optimum exposure dose determined in the sensitivity evaluation above was applied to form a 32 nm line and space pattern. The formed resist pattern was observed from above the pattern using the above scanning electron microscope. A total of 500 points of line width variation were measured, and a 3 sigma value was calculated from the distribution of the measured values, and this 3 sigma value was taken as the LWR (nm). The smaller the LWR value, the smaller the line wobble and the better it is. LWR performance was evaluated as "good" when it was 3.5 nm or less, and "poor" when it exceeded 3.5 nm.

[0274] [Table 8]

[0275] As is clear from the results in Table 8, the radiation-sensitive resin compositions of the Examples had good sensitivity and LWR performance when used for EUV exposure, whereas the Comparative Examples were inferior in each property to the Examples.

[0276] [Preparation of a negative-tone radiation-sensitive resin composition for ArF exposure, and formation and evaluation of a resist pattern using this composition] [Example 71] A radiation-sensitive resin composition (J-71) was prepared by mixing 100 parts by mass of (A-6) as the resin [A], 12.0 parts by mass of (B-8) as the compound (1), 4.0 parts by mass of (C-5) as the acid diffusion controller, 5.0 parts by mass (solids content) of (E) as the high fluorine content resin [E-3], and 3,230 parts by mass of a mixed solvent of (D-1) / (D-2) / (D-3) as the solvent, and filtering the mixture through a membrane filter having a pore size of 0.2 μm.

[0277] A composition for forming a lower anti-reflective coating ("ARC66" by Brewer Science) was applied onto a 12-inch silicon wafer using a spin coater ("CLEAN TRACK ACT12" by Tokyo Electron Co., Ltd.), and then heated at 205°C for 60 seconds to form a lower anti-reflective coating with an average thickness of 100 nm. The negative radiation-sensitive resin composition for ArF exposure (J-71) prepared above was applied onto this lower anti-reflective coating using the spin coater, and PB (pre-baking) was performed at 100°C for 60 seconds. Thereafter, a resist film with an average thickness of 90 nm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed to light through a mask pattern with 40 nm holes and 105 nm pitch using an ArF excimer laser immersion exposure device ("TWINSCAN XT-1900i" by ASML) under optical conditions of NA=1.35 and Annular (σ=0.8 / 0.6). After the exposure, PEB (post-exposure bake) was performed for 60 seconds at 100° C. Then, the resist film was developed with n-butyl acetate as an organic solvent developer, and dried to form a negative resist pattern (40 nm holes, 105 nm pitch).

[0278] <Evaluation> The resist patterns formed using the negative radiation-sensitive resin composition for ArF exposure were evaluated for CDU performance according to the following method. The resist patterns were measured using a scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000").

[0279] [CDU performance] A resist pattern with 40 nm holes and 105 nm pitch was measured at 1,800 arbitrary points from the top of the pattern using the above scanning electron microscope. The dimensional variation (3σ) was calculated and used as the CDU performance (nm). The smaller the CDU value, the smaller the variation in hole diameter over a long period and the better the result.

[0280] The resist patterns formed using the negative-tone radiation-sensitive resin compositions for ArF exposure were evaluated as described above. As a result, the radiation-sensitive resin composition of Example 71 had good sensitivity and CDU performance even when a negative-tone resist pattern was formed by ArF exposure.

[0281] [Preparation of a negative-tone radiation-sensitive resin composition for EUV exposure, and formation and evaluation of a resist pattern using this composition] [Example 72] A radiation-sensitive resin composition (J-72) was prepared by mixing 100 parts by mass of (A-13) as the resin [A], 21.0 parts by mass of (B-7) as the compound (1), 5.0 parts by mass of (C-2) as the acid diffusion controller, 3.0 parts by mass (solids content) of (E) as the high fluorine content resin [E-5], and 6,110 parts by mass of the mixed solvent of (D-1) / (D-4) as the solvent, and filtering the mixture through a membrane filter having a pore size of 0.2 μm.

[0282] A composition for forming a lower anti-reflective coating ("ARC66" by Brewer Science) was applied onto a 12-inch silicon wafer using a spin coater ("CLEAN TRACK ACT12" by Tokyo Electron Co., Ltd.), and then heated at 205°C for 60 seconds to form a lower anti-reflective coating with an average thickness of 105 nm. The negative radiation-sensitive resin composition for EUV exposure prepared above was applied onto this lower anti-reflective coating using the spin coater, and PB was performed at 130°C for 60 seconds. Thereafter, a resist film with an average thickness of 55 nm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed to light using an EUV exposure device ("NXE3300" by ASML Co., Ltd.) with NA=0.33, illumination conditions: Conventional s=0.89, and mask: imecDEFECT32FFR02. After exposure, PEB was performed at 120°C for 60 seconds. Thereafter, the resist film was developed with n-butyl acetate as an organic solvent developer, and dried to form a negative resist pattern (40 nm holes, 105 nm pitch).

[0283] The resist pattern using the negative-tone radiation-sensitive resin composition for EUV exposure was evaluated in the same manner as the resist pattern using the negative-tone radiation-sensitive resin composition for ArF exposure. As a result, the radiation-sensitive resin composition of Example 72 had good sensitivity and CDU performance even when a negative-tone resist pattern was formed by EUV exposure. [Industrial Applicability]

[0284] According to the radiation-sensitive resin composition and the method for forming a resist pattern described above, a resist pattern having good sensitivity to exposure light and excellent LWR performance and CDU performance can be formed. Therefore, these can be suitably used in the processing of semiconductor devices, which are expected to become even more miniaturized in the future.

Claims

1. An onium salt compound having a structure represented by the following formula (1-2): Solvent and A radiation-sensitive resin composition comprising: 【Chemistry 1】 (In the above formula (1-2), R ｆ１ and R ｆ２ are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. R １ is a hydrogen atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, a fluorine atom, or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. R ２ , R ５ , R ６ and R ７ are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. n １ is an integer of 1 or 2. ｆ１ and R ｆ２ If there are multiple R ｆ１ and R ｆ２ are the same or different from each other. n ２ is an integer from 0 to 4. １ and R ２ If there are multiple R １ and R ２ are the same or different from each other. However, n １ +n ２ is an integer from 2 to 6. n ３ is 0. X １ and X ２ are each independently an oxygen atom or a sulfur atom. Each * represents a bond to other structures. Z ＋ is a monovalent radiation-sensitive onium cation. R 8b and R 9b are each independently a hydrogen atom or a monovalent organic group having 1 to 40 carbon atoms, or R 8b and R 9b taken together represent a ring structure having 3 to 20 ring members formed together with the carbon atom to which they are bonded. n4 is 1.)

2. The radiation-sensitive resin composition according to claim 1 , further comprising a resin containing a structural unit having an acid-dissociable group.

3. The above R ８ｂ and R ９ｂ and each of the organic groups represented by the following formula (1) is independently a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, or a combination thereof.

4. 4. The radiation-sensitive resin composition according to claim 3, wherein the alicyclic hydrocarbon group is a monovalent monocyclic alicyclic group having 3 to 10 carbon atoms or a monovalent polycyclic alicyclic group having 6 to 14 carbon atoms.

5. The above R ８ｂ and R ９ｂ The radiation-sensitive resin composition according to any one of claims 1 to 4, wherein the ring structure having 3 to 20 ring members constituted by combining these together with the carbon atoms to which they are bonded is an alicyclic monocyclic structure having 3 to 10 carbon atoms, an alicyclic polycyclic structure having 6 to 14 carbon atoms, or an aromatic ring structure having 8 to 20 carbon atoms.

6. 6. The radiation-sensitive resin composition according to claim 1, wherein the radiation-sensitive onium cation in the formula (1-2) is a sulfonium cation or an iodonium cation.

7. In the above formula, n ２ The radiation-sensitive resin composition according to any one of claims 1 to 6, wherein is an integer of 1 to 4.

8. In the above formula, n １ +n ２ The radiation-sensitive resin composition according to any one of claims 1 to 7, wherein

9. The onium salt compound is represented by the above formula (1-2), The above R ｆ１ and R ｆ２ each independently represents a fluorine atom or a perfluoroalkyl group having 1 to 5 carbon atoms, R １ and R ２ is a hydrogen atom, n １ and n ２ is 1, X １ and X ２ 6. The radiation-sensitive resin composition according to claim 1, wherein: is an oxygen atom.

10. 3. The radiation-sensitive resin composition according to claim 2, wherein the content of the onium salt compound is from 0.01 parts by mass to 50 parts by mass based on 100 parts by mass of the resin.

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

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

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