Radiation-sensitive resin composition, pattern forming method, and radiation-sensitive acid generator

Abstract

Provided are: a radiation-sensitive resin composition, from which a resist film capable of exhibiting satisfactory levels of sensitivity, LWR performance, DOF performance, pattern rectangularity, CDU performance and pattern circularity can be formed in the formation of a resist pattern having a high aspect ratio; a pattern formation method; and a radiation-sensitive acid generator. This radiation-sensitive resin composition comprises: an onium salt compound represented by formula (1); a resin containing a structural unit (I) represented by formula (2); and a solvent. (In formula (1), R1, R2 and R3 each independently represent a monovalent organic group having 1 to 10 carbon atoms, or two or three of R1, R2 and R3 are combined with each other to form, together with a carbon atoms to which these residues are bound, a monovalent or bivalent group containing a cyclic structure having 3 to 20 carbon atoms, in which when two of R1, R2 and R3 form the above-mentioned cyclic structure, the remaining one is an organic group having 1 to 10 carbon atoms; R4 and R5 each independently represent a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group, or a monovalent fluorinated hydrocarbon group, in which when there are a plurality of R4's and R5's, the plurality of R4's and R5's are the same as or different from each other; R6, R7 and R8 each independently represent a fluorine atom or a monovalent fluorinated hydrocarbon group; m1 represents an integer of 0 to 8; and Z+ represents a monovalent radiation-sensitive onium cation.) (In formula (2), R9 represents a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group; and R10 represents a monovalent group containing at least one structure selected from the group consisting of a lactone structure, a cyclic polycarbonate structure and a sultone structure.)

Description

[Technical Field]

[0001] The present invention relates to a radiation-sensitive resin composition, a pattern-forming method, and a radiation-sensitive acid generator. [Background technology]

[0002] Photolithography, which uses resist compositions, is employed to form fine circuits in semiconductor devices. A typical procedure involves, for example, generating acid by irradiating a resist composition film with radiation through a mask pattern. This acid then acts as a catalyst, creating a difference in the solubility of the resin in alkaline or organic developers between the exposed and unexposed areas, thereby forming a resist pattern on the substrate.

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

[0004] Regarding photoacid generators, which are the main components of resist compositions, perfluoroalkyl sulfonic acid, which can impart strong acid, is widely used to improve sensitivity and resolution. On the other hand, in recent years, due to growing environmental awareness, acid generators in which only the peripheral portion of the sulfonic acid is fluorinated are being investigated (see Japanese Patent Publication No. 6761462). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 6761462 [Overview of the project] [Problems that the invention aims to solve]

[0006] One application of resist compositions is the formation of high-aspect-ratio resist patterns with line widths and hole diameters of 100 nm or less and resist film thicknesses of 100 nm to 200 nm or more. When forming such high-aspect-ratio patterns, the resist must have performance equivalent to or better than conventional resists in terms of sensitivity, LWR (Line Width Roughness) performance (indicating variations in line width and resist pattern line width), DOF (Depth of Focus) performance, pattern rectangularity (indicating the rectangularity of the cross-sectional shape of the resist pattern), critical dimension uniformity (CDU) performance (an indicator of the uniformity of line width and hole diameter), and pattern circularity (indicating the roundness of the hole shape).

[0007] The present invention aims to provide a radiation-sensitive resin composition, a pattern-forming method, and a radiation-sensitive acid generator capable of forming a resist film that exhibits sufficient levels of sensitivity, LWR performance, DOF performance, pattern rectangularity, CDU performance, and pattern circularity, even when forming a high aspect ratio resist pattern. [Means for solving the problem]

[0008] The inventors of this invention conducted extensive research to solve this problem and, as a result, found that the above objective can be achieved by adopting the following configuration, thus completing the present invention.

[0009] For example, in one embodiment, the present invention The onium salt compound represented by the following formula (1) (hereinafter also referred to as "onium salt compound (1)") and, A resin containing structural unit (I) represented by the following formula (2), Solvent and This invention relates to a radiation-sensitive resin composition containing [a specific substance]. [ka] (In formula (1), R 1 , R 2 and R3 is each independently a monovalent organic group having 1 to 10 carbon atoms or R 1 , R 2 and R 3 represent a monovalent or divalent group containing a cyclic structure having 3 to 20 carbon atoms formed by combining two or three of them together with the carbon atoms to which they are attached. When two of R 1 , R 2 and R 3 constitute the above cyclic structure, the remaining one is a monovalent organic group having 1 to 10 carbon atoms. R 4 and R 5 are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group or a monovalent fluorinated hydrocarbon group. When there are a plurality of R 4 and R 5 , the plurality of R 4 and R 5 are each the same or different. R 6 , R 7 and R 8 are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group. m1 is an integer from 0 to 8. Z + is a monovalent radiation-sensitive onium cation.)

Chemical formula

[0010] Since the radiation-sensitive resin composition contains an onium salt compound (1) as a radiation-sensitive acid generator, it is possible to form a resist film that exhibits excellent sensitivity, LWR performance, DOF performance, pattern rectangularity, CDU performance, and pattern circularity even when forming high aspect ratio resist patterns. The reason for this is presumed to be as follows, although it is not bound by any theory.

[0011] The anionic portion of the onium salt compound (1) contains a tertiary carbon atom and an ether bond adjacent to it, allowing for moderate control of the diffusion length of the generated acid while maintaining a high degree of conformational freedom. This reduces the uneven distribution of generated acid even when the resist film is thick. In addition, the interaction between the resin containing the cyclic polar structure and the onium salt compound (1) moderately controls the diffusion length of the generated acid, and the cyclic polar structure contained in the resin also improves the dissolution contrast in the developer between the exposed and unexposed areas. It is presumed that these synergistic effects enable the resist to exhibit its given properties. Note that an organic group refers to a group containing at least one carbon atom.

[0012] In another embodiment, the present invention is A step of applying the radiation-sensitive resin composition directly or indirectly to a substrate to form a resist film, The process of exposing the above-mentioned resist film, The process involves developing the exposed resist film with a developer solution. This relates to a pattern formation method, including the following:

[0013] This pattern formation method uses the above-mentioned radiation-sensitive resin composition, which is capable of forming a resist film with excellent sensitivity, LWR performance, DOF performance, pattern rectangularity, CDU performance, and pattern circularity, thus enabling the efficient formation of high-quality resist patterns.

[0014] In yet another embodiment, the present invention This invention relates to a radiation-sensitive acid generator comprising an onium salt compound represented by the following formula (1). [ka] (In formula (1), R 1 , R 2 and R 3 Each of these is independently a monovalent organic group having 1 to 10 carbon atoms, or R 1 , R 2 and R 3 R represents a monovalent or divalent group containing a cyclic structure with 3 to 20 carbon atoms, formed by combining two or three of these atoms with the carbon atoms to which they are bonded. 1 , R 2 and R 3 If two of them constitute the above cyclic structure, the remaining one is a monovalent organic group with 1 to 10 carbon atoms. R 4 and R 5 Each of these is independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group, or a monovalent fluorinated hydrocarbon group. 4 and R 5 If multiple R 4 and R 5 They are either the same or different. R 6 , R 7 and R 8 Each of these is independently a fluorine atom or a monovalent fluorinated hydrocarbon group. m1 is an integer between 0 and 8. Z + (This is a monovalent, radiation-sensitive onium cation.)

[0015] Since the radiation-sensitive acid generator consists of an onium salt compound (1) having the above-described specific structure, it can impart good sensitivity, LWR performance, DOF performance, pattern rectangularity, CDU performance, and pattern circularity to the resist film obtained when used in a radiation-sensitive resin composition. [Modes for carrying out the invention]

[0016] The embodiments of the present invention will be described in detail below, but the present invention is not limited to these embodiments. A preferred combination of embodiments is also preferable.

[0017] <Radiation sensitive resin composition> The radiation-sensitive resin composition according to this embodiment (hereinafter also simply referred to as "the composition") comprises an onium salt compound (1), a resin containing structural unit (I), and a solvent. It further optionally contains an acid diffusion control agent. The above composition may contain other optional components as long as they do not impair the effects of the present invention. By comprising an onium salt compound (1) as a radiation-sensitive acid generator and a resin containing structural unit (I) having a cyclic polar structure, the radiation-sensitive resin composition can be imparted with a high level of sensitivity, LWR performance, DOF performance, pattern rectangularity, CDU performance, and pattern circularity to the resist film of the radiation-sensitive resin composition.

[0018] (Onium salt compound (1)) The onium salt compound (1) is represented by the above formula (1) and functions as a radiation-sensitive acid generator that produces acid upon irradiation with radiation. The acid produced by exposure has the function of dissociating acid-dissociable groups in the resin and generating carboxyl groups, etc.

[0019] R 1 , R 2 and R 3The monovalent organic group having 1 to 10 carbon atoms represented by is not particularly limited and may be a chain structure, a cyclic structure, or a combination thereof. Examples of the chain structure include a chain hydrocarbon group having 1 to 10 carbon atoms, which can be saturated or unsaturated, linear or branched. Examples of the cyclic structure include a cyclic hydrocarbon group having 3 to 10 carbon atoms, which can be alicyclic, aromatic, or heterocyclic. Among these, preferred monovalent organic groups are substituted or unsubstituted monovalent chain hydrocarbon groups having 1 to 10 carbon atoms, substituted or unsubstituted monovalent alicyclic hydrocarbon groups having 3 to 10 carbon atoms, substituted or unsubstituted monovalent aromatic hydrocarbon groups having 6 to 10 carbon atoms, or combinations thereof. Other examples include groups in which some or all of the hydrogen atoms in a chain-like or cyclic structure are substituted with substituents, and groups in which CO, CS, O, S, SO2, or NR', or a combination of two or more of these, are present between carbon atoms (including between two adjacent carbon atoms and between two non-adjacent carbon atoms). R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 5 carbon atoms.

[0020] Substituents that replace some or all of the hydrogen atoms in the above organic group include, for example, halogen atoms such as fluorine, chlorine, bromine, and iodine; hydroxyl groups; carboxyl groups; cyano groups; nitro groups; amino groups; aldehyde groups; thiol groups; and oxo groups (=O) (wherein the above formula (1), R 1 , R 2 and R 3 Examples include: (It does not bond to carbon atoms adjacent to the carbon atom to which it is bonded.)

[0021] Examples of monovalent linear hydrocarbon groups having 1 to 10 carbon atoms include linear or branched saturated hydrocarbon groups having 1 to 10 carbon atoms, or linear or branched unsaturated hydrocarbon groups having 1 to 10 carbon atoms. Examples of linear or branched saturated hydrocarbon groups having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, 2-methylpropyl, 1-methylpropyl, t-butyl, n-pentyl, isopentyl, and neopentyl groups. Examples of linear or branched unsaturated hydrocarbon groups having 1 to 20 carbon atoms include alkenyl groups such as ethenyl, propenyl, and butenyl groups; and alkynyl groups such as ethynyl, propynyl, and butynyl groups.

[0022] Examples of monovalent alicyclic hydrocarbon groups having 3 to 10 carbon atoms include monocyclic or polycyclic saturated hydrocarbon groups, or monocyclic or polycyclic unsaturated hydrocarbon groups. Preferred monocyclic saturated hydrocarbon groups are cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. Preferred polycyclic cycloalkyl groups are bridged alicyclic hydrocarbon groups such as norbornyl, adamantyl, and tricyclodecyl groups. Examples of monocyclic unsaturated hydrocarbon groups include cyclopropenyl, cyclobutenyl, cyclopentenyl, and cyclohexenyl monocyclic cycloalkenyl groups. Examples of polycyclic unsaturated hydrocarbon groups are polycyclic cycloalkenyl groups such as norborneyl and tricyclodecenyl groups. A bridged alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which two carbon atoms constituting the alicyclic ring that are not adjacent to each other are bonded together by a bond chain containing one or more carbon atoms.

[0023] Examples of the above-mentioned monovalent aromatic hydrocarbon groups having 6 to 10 carbon atoms include aryl groups such as phenyl, tolyl, xyl, and naphthyl groups; and aralkyl groups such as benzyl and phenethyl groups.

[0024] Examples of the heterocyclic cyclic hydrocarbon groups mentioned above include groups obtained by removing one hydrogen atom from an aromatic heterocyclic structure and groups obtained by removing one hydrogen atom from an aliphatic heterocyclic structure. Aromatic structures with five-membered rings that acquire aromaticity by introducing a heteroatom are also included in heterocyclic structures. Examples of heteroatoms include oxygen atoms, nitrogen atoms, and sulfur atoms.

[0025] Examples of the above aromatic heterocyclic structures include, for example, Oxygen atom-containing aromatic heterocyclic structures such as furan, pyran, benzofuran, and benzopyran; Nitrogen-containing aromatic heterocyclic structures such as pyrrole, imidazole, pyridine, pyrimidine, pyrazine, indole, quinoline, and isoquinoline; Sulfur atom-containing aromatic heterocyclic structures such as thiophene; Examples include aromatic heterocyclic structures containing multiple heteroatoms such as thiazole, benzothiazole, thiazine, and oxazine.

[0026] Examples of the above aliphatic heterocyclic structures include, for example, Oxygen atom-containing aliphatic heterocyclic structures such as oxiranes, tetrahydrofurans, tetrahydropyrans, dioxolanes, and dioxanes; Nitrogen-containing aliphatic heterocyclic structures such as aziridine, pyrrolidine, piperidine, and piperazine; Sulfur atom-containing aliphatic heterocyclic structures such as thiethane, thiolane, and thian; Examples include aliphatic heterocyclic structures containing multiple heteroatoms such as morpholine, 1,2-oxathiolane, and 1,3-oxathiolane.

[0027] R 1 , R 2 and R 3 When two or three of these are combined and these are formed together with the carbon atoms to which they are bonded, the cyclic structure of carbon 3 to 20 that is included in a monovalent or divalent group is represented as follows: 1 , R 2 and R 3Examples include groups obtained by extending the above-mentioned monovalent alicyclic hydrocarbon group having 3 to 10 carbon atoms up to 20 carbon atoms, and groups obtained by removing one or two hydrogen atoms from the corresponding alicyclic hydrocarbon structure.

[0028] R 1 , R 2 and R 3 A preferred embodiment of R 1 , R 2 and R 3 These may all be substituted or unsubstituted monovalent linear hydrocarbon groups having 1 to 10 carbon atoms. Also, R 1 , R 2 and R 3 Two of these are substituted or unsubstituted monovalent linear hydrocarbon groups having 1 to 10 carbon atoms, and the remaining one may be a monovalent organic group having 3 to 10 carbon atoms that includes a cyclic hydrocarbon structure. Furthermore, R 1 , R 2 and R 3 Two of them are divalent alicyclic hydrocarbon groups with 5 to 20 carbon atoms that can be combined with the carbon atoms to which they are bonded, and the remaining one is a substituted or unsubstituted monovalent linear hydrocarbon group with 1 to 10 carbon atoms, or R 1 , R 2 and R 3 These may be monovalent alicyclic hydrocarbon groups having 6 to 20 carbon atoms, which can be combined with each other and bonded together with the carbon atoms.

[0029] As the monovalent organic group having 3 to 10 carbon atoms and containing the above-mentioned cyclic hydrocarbon structure, the above-mentioned cyclic hydrocarbon group having 3 to 10 carbon atoms, or a group formed by combining the above-mentioned monovalent organic group having 1 to 10 carbon atoms with the above-mentioned cyclic hydrocarbon group to have a total of 3 to 10 carbon atoms, can be suitably adopted.

[0030] R 1 , R 2 and R 3 Two of these can be combined with each other to form a divalent alicyclic hydrocarbon group with 5 to 20 carbon atoms, such as R 1 , R 2 and R 3In the above-mentioned monovalent alicyclic hydrocarbon group having 3 to 10 carbon atoms, a group obtained by extending this to 20 carbon atoms, specifically a group obtained by removing two hydrogen atoms from the secondary carbon atoms in the structure corresponding to 5 to 20 carbon atoms, can be suitably adopted.

[0031] R 1 , R 2 and R 3 When these are combined with each other, and together with the carbon atoms to which they are bonded, the monovalent alicyclic hydrocarbon group having 6 to 20 carbon atoms is R. 1 , R 2 and R 3 In the above-mentioned monovalent alicyclic hydrocarbon group having 3 to 10 carbon atoms, a group obtained by extending this to 20 carbon atoms, specifically a group in which one hydrogen atom is removed from the tertiary carbon atom in the structure corresponding to 6 to 20 carbon atoms, can be suitably adopted.

[0032] R 4 and R 5 As the monovalent hydrocarbon group represented by , the monovalent chain hydrocarbon group having 1 to 10 carbon atoms, the monovalent alicyclic hydrocarbon group having 3 to 10 carbon atoms, the monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms, or a combination thereof can be suitably adopted.

[0033] R 4 , R 5 , R 6 , R 7 and R 8 Examples of monovalent fluorinated hydrocarbon groups represented by this formula include monovalent fluorinated linear hydrocarbon groups having 1 to 20 carbon atoms and monovalent fluorinated alicyclic hydrocarbon groups having 3 to 20 carbon atoms.

[0034] Examples of the above monovalent fluorinated chain hydrocarbon groups having 1 to 20 carbon atoms include, for example, Fluorinated alkyl groups such as trifluoromethyl group, 2,2,2-trifluoroethyl group, pentafluoroethyl group, 2,2,3,3,3-pentafluoropropyl group, 1,1,1,3,3,3-hexafluoropropyl group, heptafluoro n-propyl group, heptafluoro i-propyl group, nonafluoro n-butyl group, nonafluoro i-butyl group, nonafluoro t-butyl group, 2,2,3,3,4,4,5,5-octafluoro n-pentyl group, tridecafluoro n-hexyl group, 5,5,5-trifluoro-1,1-diethylpentyl group, etc.; Fluorinated alkenyl groups such as trifluoroethenyl group, pentafluoropropenyl group, etc.; Fluorinated alkynyl groups such as fluoroethynyl group, trifluoropropynyl group, etc. may be mentioned.

[0035] Examples of the monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms include Fluorinated cycloalkyl groups such as fluorocyclopentyl group, difluorocyclopentyl group, nonafluorocyclopentyl group, fluorocyclohexyl group, difluorocyclohexyl group, undecafluorocyclohexylmethyl group, fluoronorbornyl group, fluoroadamantyl group, fluorobornyl group, fluoroisobornyl group, fluorotricyclodecyl group, etc.; Fluorinated cycloalkenyl groups such as fluorocyclopentenyl group, nonafluorocyclohexenyl group, etc., may be mentioned

[0036] As the fluorinated hydrocarbon group, the monovalent fluorinated chain hydrocarbon group having 1 to 8 carbon atoms is preferable, and the monovalent fluorinated straight-chain hydrocarbon group having 1 to 5 carbon atoms is more preferable.

[0037] R 4 and R 5 From the viewpoint of the degree of freedom of the anion structure, each is independently preferably a hydrogen atom, a fluorine atom, a monovalent straight-chain saturated hydrocarbon group having 1 to 5 carbon atoms or a monovalent fluorinated straight-chain hydrocarbon group having 1 to 5 carbon atoms. R 6 R 7 and R 8In terms of the degree of freedom of the surrounding structure of the sulfo group and the acidity of the generated acid, a fluorine atom or a monovalent fluorinated linear hydrocarbon group having 1 to 5 carbon atoms is preferred, and it is more preferable that all atoms are fluorine atoms.

[0038] m1 is preferably an integer between 0 and 6, more preferably an integer between 0 and 4, even more preferably an integer between 0 and 3, and particularly preferably an integer between 1 and 3.

[0039] Specific examples of the anionic portion of the onium salt compound (1) include, but are not limited to, the structures shown in formulas (1-1-1) to (1-1-37) below.

[0040] [ka]

[0041] [ka]

[0042] In the above equation (1), the above Z + Examples of monovalent radiosensitive onium cations represented by the formulas (X-1) to (X-6) below include radiodegradable onium cations containing elements such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, and Bi. Examples of radiodegradable onium cations include sulfonium cations, tetrahydrothiophenium cations, iodonium cations, phosphonium cations, diazonium cations, and pyridinium cations. Among these, sulfonium cations or iodonium cations are preferred. Sulfonium cations or iodonium cations are preferably represented by the following formulas (X-1) to (X-6).

[0043] [ka]

[0044] In the above equation (X-1), Ra1 , R a2 and R a3 are each independently a substituted or unsubstituted linear or branched alkyl group, alkoxy group or alkoxycarbonyloxy group having 1 to 12 carbon atoms, 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 , -S-R T , -O-, -CO- or a combination thereof, or represents a ring structure formed by combining two or more of these groups. The ring structure may contain heteroatoms such as O or S between carbon-carbon bonds forming 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 from to 5. R a1 ~R a3 as well as R P , R Q and R T when each is plural, the plural R a1 ~R a3 as well as R P , R Q and R T may be the same or different from each other.

[0045] In the above formula (X-2), R b1 is a substituted or unsubstituted linear or branched alkyl group or alkoxy group having 1 to 20 carbon atoms, an alkoxyalkyloxy group, a substituted or unsubstituted acyl group having 2 to 8 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxy group. n k is 0 or 1. n k When n is 0, k4 is an integer from 0 to 4, and when n k is 1, k4 is an integer from 0 to 7. Rb1 If there are multiple, then multiple R b1 They may be the same or different, and there may be multiple R b1 R may represent a ring structure formed by combining with other elements. b2 This 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 k5 is a single bond or a divalent linking group. k5 is an integer from 0 to 4. b2 If there are multiple, then multiple R b2 They may be the same or different, and there may be multiple R b2 may represent a ring structure formed by combining with each other. q is an integer between 0 and 3. In the formula, S + The ring structure containing may include heteroatoms such as O and S between the carbon-carbon bonds that form the skeleton.

[0046] In the above equation (X-3), R c1 , R c2 and R c3 Each of these is independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms.

[0047] In the above equation (X-4), R g1 This 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, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms, or a hydroxyl group. k2 n is either 0 or 1. k2 When k10 is 0, k10 is an integer from 0 to 4, and n k2 When k10 is 1, k10 is an integer from 0 to 7. g1 If there are multiple, then multiple R g1 They may be the same or different, and there may be multiple R g1 R may represent a ring structure formed by combining with other elements. g2 is and R g3Each of these independently represents a substituted or unsubstituted linear or branched alkyl group, alkoxy group or alkoxycarbonyloxy group having 1 to 12 carbon atoms, a substituted or unsubstituted monocyclic or polycyclic cycloalkyl group having 3 to 12 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group, hydroxyl group, halogen atom having 6 to 12 carbon atoms, or a ring structure formed by combining these groups. k11 and k12 are each independently integers from 0 to 4. R g2 is and R g3 If each of them is multiple, then multiple R g2 is and R g3 These may be the same or different.

[0048] In the above equation (X-5), R d1 and R d2 Each of these independently represents a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, an alkoxy group or 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 two or more of these groups being combined. k6 and k7 are each independently integers from 0 to 5. d1 and R d2 If each of them is multiple, then multiple R d1 and R d2 These may be the same or different.

[0049] In the above equation (X-6), R e1 and R e2 k8 and k9 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.

[0050] Specific examples of the above-mentioned radiation-sensitive onium cation include, but are not limited to, the structures shown in formulas (1-2-1) to (1-2-52) below.

[0051] [ka]

[0052] [ka]

[0053] [ka]

[0054] The onium salt compound (1) can be obtained by appropriately combining the above-mentioned anionic moiety and the above-mentioned radiation-sensitive onium cation. Specific examples, though not limited to them, include structures such as those shown in formulas (1-1) to (1-38) below.

[0055] [ka]

[0056] [ka]

[0057] The lower limit of the onium salt compound (1) content (total if multiple types of onium salt compounds (1) are included) is preferably 0.1 parts by mass, more preferably 0.5 parts by mass, even more preferably 1 part by mass, and particularly preferably 3 parts by mass per 100 parts by mass of the resin described later. The upper limit of the above content is preferably 50 parts by mass, more preferably 40 parts by mass, even more preferably 30 parts by mass, and particularly preferably 25 parts by mass. The onium salt compound (1) content is appropriately selected depending on the type of resin used, exposure conditions, and the required sensitivity. This enables excellent sensitivity, LWR performance, DOF performance, pattern rectangularity, CDU performance, and pattern circularity during resist pattern formation.

[0058] (Method for synthesizing onium salt compound (1)) As a method for synthesizing the onium salt compound (1), in formula (1) above, R 4 and R 5 Both are hydrogen atoms, R 6 , R 7 and R 8 We will explain using the example where both are fluorine atoms and m1 is 2. A typical scheme is shown below.

[0059] [ka]

[0060] In the above scheme, R 1 , R 2 , R 3 and Z + This is equivalent to equation (1) above.

[0061] The bromo portion of 4-bromo-2,2,3,3-tetrafluoro-1-ol is converted to a sulfonate using a dithionite and an oxidizing agent, and the onium cation halide salt (bromide salt in the scheme) corresponding to the onium cation portion is reacted with the onium cation halide salt to proceed with salt exchange and obtain the onium salt. Finally, the hydroxyl group of the onium salt and R 1 , R 2 and R 3 The desired onium salt compound (1) represented by formula (1a) can be synthesized by dehydrating it with a tertiary alcohol having the structure shown. Other onium salt compounds (1) having different structures can be synthesized in a similar manner by appropriately selecting starting materials and precursors corresponding to the anionic and onium cation parts.

[0062] (resin) The resin is an aggregate of polymers containing structural unit (I) represented by formula (2) above (hereinafter this resin is also referred to as the "base resin"). The base resin preferably contains structural unit (II) having an acid-dissociable group, as described later, in addition to structural unit (I), and may also contain other structural units other than structural units (I) and (II). Each structural unit will be described below.

[0063] [Structural Unit (I)] Structural unit (I) is represented by formula (2) above and is a structural unit that includes at least one structure selected from the group consisting of lactone structures, cyclic carbonate structures, and sultone structures. The base resin can have its solubility in the developer adjusted by further containing structural unit (I), 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.

[0064] The cyclic structure that forms the basis of the cyclic polar structure contained in structural unit (I) may be a monocyclic structure with one ring (i.e., constituting a monocyclic polar structure), or a polycyclic structure with two, three, four, five, or six or more rings (i.e., constituting a polycyclic polar structure). The cyclic structure may be an alicyclic structure, an aromatic ring structure, or a combination thereof. If the above cyclic structure is a polycyclic structure, the bonding mode of two adjacent rings is not particularly limited, and may be a structure in which two adjacent rings share two or more carbon atoms (fused ring structure, bridged ring structure, etc.), a structure in which two adjacent rings are joined by a single bond, a spiro structure in which two adjacent rings share one carbon atom, or a structure that combines these. At least one of the rings forming these monocyclic or polycyclic structures has to have a lactone structure, a sultone structure, or a cyclic carbonate structure. Furthermore, if a single structural unit (I) contains both a monocyclic polar structure and a polycyclic polar structure (the polar structures may be the same or different), that structural unit (I) is treated as a structural unit having a polycyclic polar structure.

[0065] R in equation (2) above 10 It is preferable that the structure is a polycyclic lactone structure, a polycyclic carbonate structure, or a polycyclic sultone structure. Among these, R 10 The polycyclic lactone structure in the above is preferably a norbornane lactone structure or an adamantane lactone structure.

[0066] As the above structural unit (I), R 10The structural unit in which is a monovalent group containing a polycyclic lactone structure is preferably represented by the following formulas (T-1-1), (T-1-2), or (T-1-3). [ka] (In the above formulas (T-1-1) to (T-1-3), R L1 These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R L2 Each of these is independently a hydrogen atom, a C1-C4 alkyl group, a cyano group, a trifluoromethyl group, an alkoxy group, a (cyclo)alkoxycarbonyl group, a hydroxyl group, a hydroxyalkyl group, a dimethylamino group, or a lactone structure. L2 If multiple R L2 They are the same or different. L 1 Each of these is independently a single bond or a divalent linking group. X 1 Each of these is independently either an oxygen atom or a methanediyl group. d1 is an integer between 0 and 3.

[0067] R L1 From the viewpoint of copolymerization of monomers that give structural unit (II), hydrogen atoms and methyl groups are preferred, and methyl groups are more preferred.

[0068] R L2 Examples of alkyl groups represented by this symbol include linear or branched alkyl groups having 1 to 10 carbon atoms, such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, and t-butyl group.

[0069] R L2 Examples of alkoxy groups represented by this symbol include linear or branched alkoxy groups having 1 to 10 carbon atoms, such as methoxy groups, ethoxy groups, n-propoxy groups, i-propoxy groups, n-butoxy groups, and t-butoxy groups.

[0070] R L2 Examples of (cyclo)alkoxycarbonyl groups represented by include linear or branched alkoxycarbonyl groups having 1 to 10 carbon atoms, such as methoxycarbonyl group, ethoxycarbonyl group, n-propoxycarbonyl group, i-propoxycarbonyl group, n-butoxycarbonyl group, and t-butoxycarbonyl group, and cycloalkoxycarbonyl groups having 3 to 10 carbon atoms, such as cyclopropoxycarbonyl group, cyclobutoxycarbonyl group, cyclopropoxycarbonyl group, cyclopentyloxycarbonyl group, 1-methylcyclopentyloxycarbonyl group, 1-ethylcyclopentyloxycarbonyl group, and cyclohexyloxycarbonyl group.

[0071] R L2 Examples of hydroxyalkyl groups represented by this symbol include groups in which some or all of the hydrogen atoms of a linear or branched alkyl group having 1 to 10 carbon atoms, such as a hydroxymethyl group, a hydroxyethyl group, a hydroxypropyl group, or a hydroxybutyl group, are substituted with hydroxyl groups.

[0072] R L2 Examples of groups containing the lactone structure represented by the formula (L2) below include the group represented by the formula (L2). [ka] (In formula (L2), L 11 These are single bonds, divalent hydrocarbon groups having 1 to 10 carbon atoms, -CO-, -O-, -NH-, or combinations thereof. R L22 R is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a cyano group, a trifluoromethyl group, an alkoxy group, a (cyclo)alkoxycarbonyl group, a hydroxyl group, a hydroxyalkyl group, or a dimethylamino group. L22 If multiple R L22 They are the same or different. nL1 is an integer between 1 and 3. nL2 is an integer between 0 and 3. * represents a bond with the ring structure in the above formulas (T-1-1), (T-1-2), or (T-1-3).

[0073] L 11 As a divalent hydrocarbon group having 1 to 10 carbon atoms represented by the above R 4 and R 5 A group obtained by removing one hydrogen atom from a monovalent hydrocarbon group represented by can be suitably adopted. 11 Preferably, the group is a chain-like hydrocarbon group having 1 to 10 carbon atoms, -CO-, -O-, or a combination thereof; more preferably, a linear hydrocarbon group having 1 to 5 carbon atoms, -CO-, -O-, or a combination thereof; and even more preferably, a linear hydrocarbon group having 1 to 5 carbon atoms or a combination of a linear hydrocarbon group having 1 to 5 carbon atoms and -COO-.

[0074] R L22 The structure is R in the above equations (T-1-1) to (T-1-3) L2 The structure (excluding the group containing the lactone structure) can be suitably adopted.

[0075] nL1 is preferably 1 or 2. nL2 is preferably an integer between 0 and 2, and more preferably 0 or 1.

[0076] In the above formulas (T-1-1) to (T-1-3), L 1 Examples of divalent linking groups represented by include alkanediyl groups, cycloalkanediyl groups, alkenediyl groups, and -R LA O- * , -R LB COO- * Or combinations of these are possible (* indicates a bond on the ring structure side).

[0077] As the above alkanediyl group, an alkanediyl group having 1 to 8 carbon atoms is preferred.

[0078] Examples of the above-mentioned cycloalkanediyl groups include monocyclic cycloalkanediyl groups such as cyclopentanediyl and cyclohexanediyl groups, and polycyclic cycloalkanediyl groups such as norbornanediyl and adamantanediyl groups. A cycloalkanediyl group having 5 to 12 carbon atoms is preferred.

[0079] Examples of the alkenediyl group mentioned above include ethendiyl group, propenediyl group, and butenediyl group. A preferred alkenediyl group is one having 2 to 6 carbon atoms.

[0080] The above -R LA O- * R LA Examples include the above-mentioned alkanediyl group, the above-mentioned cycloalkanediyl group, the above-mentioned alkenediyl group, etc. Above-R LB COO- * R LB Examples of these groups include the alkanediyl group, cycloalkanediyl group, alkenediyl group, and arenediyl group. Examples of arenediyl groups include benzenediyl group, torylene group, and naphthalenediyl group. Among the above arenediyl groups, arenediyl groups having 6 to 15 carbon atoms are preferred.

[0081] Among these, L c is a single bond or -R LB COO- * It is preferable that this is the case. LB An alkanediyl group is preferred as the group.

[0082] L 1 Some or all of the hydrogen atoms on the carbon atoms inside may be substituted with halogen atoms such as fluorine or chlorine atoms, alkyl halides such as trifluoromethyl groups, alkoxy groups such as methoxy groups, cyano groups, etc.

[0083] X 1 It is preferable that it is a methanediyl group.

[0084] d1 is preferably an integer between 0 and 2, and more preferably 0 or 1.

[0085] R 10 Examples of monomeric compounds that give a monovalent structural unit (II) containing a polycyclic lactone structure include the compound represented by the following formula. [ka]

[0086] [ka]

[0087] As the above structural unit (II), R 10 The structural unit in which is a monovalent group containing a polycyclic sultone structure is preferably represented by the following formulas (T-2-1), (T-2-2), or (T-2-3). [ka] (In the above formulas (T-2-1) to (T-2-3), R S1 These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R S2 Each of these is independently a hydrogen atom, a C1-C4 alkyl group, a cyano group, a trifluoromethyl group, an alkoxy group, a (cyclo)alkoxycarbonyl group, a hydroxyl group, a hydroxyalkyl group, a dimethylamino group, or a lactone structure. S2 If multiple R S2 They are the same or different. L 2 Each of these is independently a single bond or a divalent linking group. X 2 Each of these is independently either an oxygen atom or a methanediyl group. d2 is an integer between 0 and 3.

[0088] The above R S1 , R S2 , L2 , X 2 For d2, the R values ​​in the above equations (T-1-1) to (T-1-3) are respectively. L1 , R L2 , L 1 , X 1 The structure or value shown in d1 can be preferably adopted.

[0089] R 10 Examples of monomeric compounds that give a structural unit in which a monovalent group containing a polycyclic sultone structure include the compound represented by the following formula. [ka]

[0090] [ka]

[0091] As a structural unit (II), R 10 The structural unit in which is a monovalent group containing a polycyclic carbonate structure is preferably represented by the following formula (T-3-1) or (T-3-2). [ka] (In the above formulas (T-3-1) to (T-3-2), R T1 These are, independently, a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R T2 Each of these is independently a hydrogen atom, a C1-C4 alkyl group, a cyano group, a trifluoromethyl group, an alkoxy group, a (cyclo)alkoxycarbonyl group, a hydroxyl group, a hydroxyalkyl group, a dimethylamino group, or a lactone structure. T2 If multiple R T2 They are the same or different. L 3 Each of these is independently a single bond or a divalent linking group. X 3Each of these is independently either an oxygen atom or a methanediyl group. nt is an integer between 1 and 3. d3 is an integer between 0 and 3.

[0092] The above R T1 , R T2 , L 3 , X 3 For d3, the R values ​​in the above equations (T-1-1) to (T-1-3) are respectively. L1 , R L2 , L 1 , X 1 The structure or value shown in d1 can be preferably adopted.

[0093] R 10 Examples of monomeric compounds that give a monovalent group structural unit containing a polycyclic carbonate structure include the compound represented by the following formula. [ka]

[0094] As the above structural unit (I), R 10 The structural unit in which is a monovalent group containing a monocyclic lactone structure is R in formula (2) above. 10 It is preferable that the structural unit is a group represented by the above formula (L2) (however, in this case, * in the above formula (L2) is a bond with the oxygen atom of the above formula (2)).

[0095] R 10 Examples of monomeric compounds that give a structural unit which is a monovalent group containing a monocyclic carbonate structure include the compound represented by the following formula. [ka]

[0096] As the above structural unit (I), R 10 The structural unit in which is a monovalent group containing a monocyclic sultone structure is preferably represented by the following formula (T-2-11). [ka] (In the above formula (T-2-11), R S1 , R S2 , L 2 These are equivalent to the above equation (T-2-1). t1 (where d21 is an integer between 1 and 3, and d21 is an integer between 0 and 2.)

[0097] R 10 Examples of monomeric compounds that give a structural unit containing a monocyclic sultone structure and a monovalent group include the compound represented by the following formula. [ka]

[0098] As the above structural unit (I), R 10 The structural unit in which is a monovalent group containing a monocyclic carbonate structure is preferably represented by the following formula (T-3-11). [ka] (In the above formula (T-3-11), R T1 , R T2 , L 3 These are equivalent to the above equation (T-3-1). t2 (where d31 is an integer between 1 and 3, and d31 is an integer between 0 and 2.)

[0099] R 10 Examples of monomeric compounds that give a structural unit which is a monovalent group containing a monocyclic carbonate structure include the compound represented by the following formula. [ka]

[0100] The base resin may contain one or more structural units (I) in combination.

[0101] The lower limit of the content ratio of structural unit (I) in all the structural units constituting the base resin (when including a plurality of types, the total content ratio) is preferably 1 mol%, more preferably 10 mol%, still more preferably 20 mol%, and particularly preferably 30 mol%. Further, the upper limit of the content ratio is preferably 80 mol%, more preferably 75 mol%, still more preferably 70 mol%, and particularly preferably 65 mol%. By setting the content ratio of structural unit (I) within the above range, the radiation-sensitive resin composition can further improve lithography performance such as resolution and the adhesion of the formed resist pattern to the substrate.

[0102] [Structural unit (II)] Structural unit (II) is a structural unit containing an acid dissociable group. The "acid dissociable group" is a group that substitutes a hydrogen atom of a carboxy group, phenolic hydroxyl group, alcoholic hydroxyl group, sulfo group, etc., and dissociates by the action of an acid. The radiation-sensitive resin composition is excellent in pattern formability because the resin has structural unit (II).

[0103] Structural unit (II) is not particularly limited as long as it contains an acid dissociable group. For example, a structural unit having a tertiary alkyl ester moiety, a structural unit having a structure in which the hydrogen atom of a phenolic hydroxyl group is substituted with a tertiary alkyl group, a structural unit having an acetal bond, etc. can be mentioned. From the viewpoint of improving the pattern formability of the radiation-sensitive resin composition, the structural unit represented by the following formula (3) (hereinafter, also referred to as "structural unit (II-1)") is preferable.

[0104] [Chemical formula]

[0105] In the above formula (3), R 17 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R 18 is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R 19 and R 20Each independently represents a monovalent linear hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a divalent alicyclic group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are attached.

[0106] The above R 17 From the viewpoint of the copolymerizability of the monomer that gives the structural unit (II-1), a hydrogen atom and a methyl group are preferable, and a methyl group is more preferable.

[0107] The above R 18 Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the above R include a linear hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, and the like.

[0108] The above R 18 ~R 20 As the linear hydrocarbon group having 1 to 10 carbon atoms represented by the above, the monovalent linear hydrocarbon group having 1 to 10 carbon atoms in R, R, and R in the above formula (1) can be preferably adopted. 1 R 2 And R 3 Regarding the monovalent linear hydrocarbon group having 1 to 10 carbon atoms, it can be preferably adopted.

[0109] The above R 18 ~R 20 As the alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the above, a group obtained by expanding the monovalent alicyclic hydrocarbon group having 3 to 10 carbon atoms in R, R, and R in the above formula (1) to 20 carbon atoms can be preferably adopted. 1 R 2 And R 3 Regarding the monovalent alicyclic hydrocarbon group having 3 to 10 carbon atoms, it can be preferably adopted.

[0110] The above R 18 As the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by the above, a group obtained by expanding the monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms in R, R, and R in the above formula (1) to 20 carbon atoms can be preferably adopted. 1 R 2 And R 3 Regarding the monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms, it can be preferably adopted.

[0111] The above R 18Preferred carbon atoms include linear or branched saturated hydrocarbon groups having 1 to 10 carbon atoms, and alicyclic hydrocarbon groups having 3 to 20 carbon atoms.

[0112] The above R 19 and R 20 A divalent alicyclic group having 3 to 20 carbon atoms, formed by combining chain-like hydrocarbon groups or alicyclic hydrocarbon groups represented by the above formula with the carbon atoms to which they are bonded, is not particularly limited as long as it is a group obtained by removing two hydrogen atoms from the same carbon atom constituting the carbon ring of a monocyclic or polycyclic alicyclic hydrocarbon of the above carbon number. It may be either a monocyclic hydrocarbon group or a polycyclic hydrocarbon group, and as a polycyclic hydrocarbon group, it 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. A condensed alicyclic hydrocarbon group refers to a polycyclic alicyclic hydrocarbon group in which multiple alicyclics share an edge (a bond between two adjacent carbon atoms).

[0113] Among 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. Among polycyclic alicyclic hydrocarbon groups, bridged alicyclic saturated hydrocarbon groups are preferred, 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 3,7 A decane-2,2-diyl group (adamantane-2,2-diyl group) is preferred.

[0114] Among these, R 18 R is an alkyl group having 1 to 4 carbon atoms. 19 and R 20 It is preferable that the alicyclic structure formed by combining these atoms with the carbon atoms to which they are bonded is a polycyclic or monocyclic cycloalkane structure.

[0115] Examples of structural units (I-1) include structural units represented by the following formulas (3-1) to (3-6) (hereinafter also referred to as "structural units (II-1-1) to (II-1-6)").

[0116] [ka]

[0117] In the above equations (3-1) to (3-6), R 17 ~R 20 This is equivalent to equation (3) above. i and j are independent integers between 1 and 4. k and l are 0 or 1.

[0118] i and j are preferably 1. 18 As such, a methyl group, ethyl group, isopropyl group, t-butyl group, or cyclopentyl group is preferred. 19 and R 20 A methyl group or an ethyl group is preferred.

[0119] The base resin may contain one or more structural units (II) in combination.

[0120] The lower limit of the content of structural unit (II) (total content if multiple types are included) is preferably 10 mol%, more preferably 20 mol%, even more preferably 30 mol%, and particularly preferably 35 mol%, relative to the total structural units constituting the base resin. The upper limit of the above content is preferably 80 mol%, more preferably 75 mol%, even more preferably 70 mol%, and particularly preferably 65 mol%. By setting the content of structural unit (II) within the above range, the pattern-forming properties of the radiation-sensitive resin composition can be further improved.

[0121] [Structural Unit (III)] In addition to the above structural units (I) and (II), the base resin may optionally have other structural units. Examples of the other structural units include structural units (III) containing a polar group (excluding those corresponding to structural unit (I)). By further having structural unit (III), the solubility of the base resin in the developer can be adjusted, and as a result, the lithography performance such as the resolution of the radiation-sensitive resin composition can be improved. Examples of the polar group include a hydroxy group, a carboxy group, a cyano group, a nitro group, a sulfonamide group, etc. Among these, a hydroxy group and a carboxy group are preferable, and a hydroxy group is more preferable.

[0122] Examples of structural unit (III) include structural units represented by the following formula.

[0123] [Chemical formula]

[0124] In the above formula, R A is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0125] When the base resin has structural unit (III) having the above polar group, the lower limit of the content ratio of structural unit (III) is preferably 2 mol%, more preferably 5 mol%, and even more preferably 8 mol% with respect to all the structural units constituting the base resin. The upper limit of the content ratio is preferably 30 mol%, more preferably 20 mol%, and even more preferably 15 mol%. By setting the content ratio of structural unit (III) within the above range, the lithography performance such as the resolution of the radiation-sensitive resin composition can be further improved.

[0126] [Structural unit (IV)] The base resin may optionally contain structural units having phenolic hydroxyl groups (hereinafter, both are collectively referred to as "structural unit (IV)") in addition to structural unit (III) having polar groups. Structural unit (IV) contributes to improved etching resistance and improved difference in developer solubility (dissolution contrast) between exposed and unexposed areas. In particular, it can be suitably applied to pattern formation using exposure with radiation of wavelength 50 nm or less, such as electron beams and EUV. In this case, it is preferable that the resin contains structural unit (I) along with structural unit (IV).

[0127] Structural units (IV) are represented, for example, by the following formulas (4-1) to (4-4).

[0128] [ka]

[0129] In the above equations (4-1) to (4-4), R 41 Each of these is independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Y is a halogen atom, a trifluoromethyl group, a cyano group, an alkyl or alkoxy group having 1 to 6 carbon atoms, or an acyl group, acyloxy group, or alkoxycarbonyl group having 2 to 7 carbon atoms. If there are multiple Ys, they are either identical or different from each other. t is an integer from 0 to 4.

[0130] When obtaining structural unit (IV), it is preferable to polymerize the corresponding monomer with the phenolic hydroxyl group protected by a protecting group such as an alkali-dissociable group (e.g., an acyl group) during polymerization, and then deprotect it by hydrolysis to obtain structural unit (IV). Alternatively, the corresponding monomer may be polymerized without protecting the phenolic hydroxyl group.

[0131] For resins used for exposure with radiation of wavelength 50 nm or less, the lower limit of the content of structural unit (IV) is preferably 10 mol%, and more preferably 15 mol%, relative to the total structural units constituting the resin. The upper limit of the above content is preferably 50 mol%, and more preferably 40 mol%.

[0132] [Other structural units] The base resin may include structural units having an alicyclic structure represented by the following formula (6), in addition to 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 (It is a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms.)

[0133] In the above formula (6), R 2α As a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the above formula (3), the above R 18 ~R 20 A monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, represented by [the formula shown], can be suitably used.

[0134] When the base resin contains structural units having the above-mentioned alicyclic structure, the lower limit of the content of structural units having the above-mentioned alicyclic structure is preferably 2 mol%, more preferably 5 mol%, and even more preferably 8 mol%, relative to the total structural units constituting the base resin. The upper limit of the above-mentioned content is preferably 30 mol%, more preferably 20 mol%, and even more preferably 15 mol%.

[0135] (Method of synthesizing the base resin) The base resin can be synthesized, for example, by polymerizing monomers that provide each structural unit in a suitable solvent using a radical polymerization initiator or the like.

[0136] Examples of the radical polymerization initiators mentioned above include azo-based 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-based 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 individually or in combination of two or more.

[0137] Examples of solvents used in the polymerization described above 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, 2-butanone (methyl ethyl ketone), 4-methyl-2-pentanone, and 2-heptanone; Ethers such as tetrahydrofuran, dimethoxyethanes, and diethoxyethanes; Examples include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 4-methyl-2-pentanol, and 1-methoxy-2-propanol. The solvent used in these polymerizations may be used alone or in combination of two or more.

[0138] The reaction temperature in the polymerization described above is typically 40°C to 150°C, with 50°C to 120°C being preferred. The reaction time is typically 1 hour to 48 hours, with 1 hour to 24 hours being preferred.

[0139] The molecular weight of the base resin is not particularly limited, but the lower limit of the polystyrene-equivalent weight-average molecular weight (Mw) determined by gel permeation chromatography (GPC) is preferably 2,000, more preferably 3,000, even more preferably 4,000, and particularly preferably 4,500. The upper limit of Mw is preferably 30,000, more preferably 20,000, even more preferably 10,000, and particularly preferably 8,000. By setting the Mw of the base resin within the above range, the resulting resist film can exhibit good heat resistance and developability.

[0140] The ratio of Mw (Mw / Mn) to the polystyrene-equivalent number-average molecular weight (Mn) of the base resin, calculated by GPC, is usually between 1 and 5, preferably between 1 and 3, and more preferably between 1 and 2.

[0141] In this specification, the Mw and Mn values ​​of the resin are measured using gel permeation chromatography (GPC) under the following conditions.

[0142] GPC columns: 2 x G2000HXL, 1 x G3000HXL, 1 x G4000HXL (all manufactured by Tosoh) Column temperature: 40℃ Leaching 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

[0143] The base resin content is preferably 60% by mass or more, more preferably 65% ​​by mass or more, and even more preferably 70% by mass or more, relative to the total solid content of the radiation-sensitive resin composition.

[0144] (Other resins) The radiation-sensitive resin composition of this embodiment may also contain, as another resin, a resin with a higher mass content of fluorine atoms than the base resin (hereinafter also referred to as "high-fluorine content resin"). When the radiation-sensitive resin composition contains a high-fluorine content resin, it can be unevenly distributed on the surface of the resist film relative to the base resin, and as a result, it is possible to improve the water repellency of the surface of the resist film during immersion exposure, or to control the surface modification of the resist film and the distribution of the composition within the film during EUV exposure.

[0145] The high-fluorine-content resin preferably has a structural unit represented by the following formula (5) (hereinafter also referred to as "structural unit (V)"), and may also have structural unit (II) or structural unit (III) in the base resin as needed.

[0146] [ka]

[0147] In the above equation (5), R 13 This is a hydrogen atom, a methyl group, or a trifluoromethyl group. L R consists of a single bond, an alkanediyl group with 1 to 5 carbon atoms, an oxygen atom, a sulfur atom, -COO-, -SO2ONH-, -CONH-, -OCONH-, or a combination thereof. 14 This is a monovalent fluorinated chain hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 20 carbon atoms.

[0148] The above R 13 From the viewpoint of copolymerization of monomers that provide structural unit (V), hydrogen atoms and methyl groups are preferred, and methyl groups are more preferred.

[0149] The above G L From the viewpoint of copolymerization of monomers that provide structural unit (V), combinations of single bonds, -COO-, -COO- and alkanediyl groups having 1 to 5 carbon atoms are preferred, with -COO- being more preferred.

[0150] The above R 14 Examples of monovalent fluorinated linear hydrocarbon groups having 1 to 20 carbon atoms, represented by , include those in which some or all of the hydrogen atoms in a linear or branched alkyl group having 1 to 20 carbon atoms are substituted with fluorine atoms.

[0151] The above R 14 Examples of monovalent fluorinated alicyclic hydrocarbon groups having 3 to 20 carbon atoms, represented by , include those in which some or all of the hydrogen atoms in a monocyclic or polycyclic hydrocarbon group having 3 to 20 carbon atoms are substituted with fluorine atoms.

[0152] The above R 14 Preferably, the group is a fluorinated chain hydrocarbon group, more preferably a fluorinated alkyl group, and even more preferably a 2,2,2-trifluoroethyl group, a 2,2,3,3,3-pentafluoropropyl group, a 1,1,1,3,3,3-hexafluoropropyl group, and a 5,5,5-trifluoro-1,1-diethylpentyl group.

[0153] When a high-fluorine-content resin has structural units (V), the lower limit of the content of structural units (V) is preferably 40 mol%, more preferably 50 mol%, and even more preferably 55 mol%, relative to the total structural units constituting the high-fluorine-content resin. The upper limit of the above content is preferably 80 mol%, more preferably 70 mol%, and even more preferably 65 mol%. By setting the content of structural units (V) within the above range, the mass content of fluorine atoms in the high-fluorine-content resin can be more appropriately adjusted, further promoting the uneven distribution of fluorine atoms on the surface of the resist film, and as a result, the water repellency of the resist film during immersion exposure can be further improved.

[0154] High-fluorine content resins may have fluorine atom-containing structural units (hereinafter also referred to as structural unit (VI)) represented by the following formula (f-2), either together with or in place of structural unit (V). The presence of structural unit (f-2) in high-fluorine content resins improves solubility in alkaline developers and suppresses the occurrence of development defects.

[0155] [ka]

[0156] Structural units (VI) can be broadly classified into two types: (x) those having an alkali-soluble group, and (y) those having a group that dissociates upon the action of alkali, increasing its solubility in an alkaline developer (hereinafter also simply referred to as an "alkali-dissociable group"). In both (x) and (y), in the above formula (f-2), R C R is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. D This is a single bond, a (s+1) valent hydrocarbon group with 1 to 20 carbon atoms, and the R of this hydrocarbon group E At the terminal end of the side are an oxygen atom, a sulfur atom, and -NR dd -, a structure to which a carbonyl group, -COO-, -OCO-, or -CONH- is bonded, or a structure in which some of the hydrogen atoms of this hydrocarbon group are replaced by an organic group having a heteroatom. dd is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. s is an integer from 1 to 3.

[0157] If structural unit (VI) has (x) an alkali-soluble group, R F is a hydrogen atom, A 1 * is an oxygen atom, -COO-* or -SO2O-*. F This shows the site of binding. 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, then W 1 is A 1 It is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group at the carbon atom to which it is bonded. E is a single bond or a divalent organic group with 1 to 20 carbon atoms. If s is 2 or 3, there are multiple R E , W 1 , A 1 and R FThese may be the same or different. Having (x) an alkali-soluble group in structural unit (VI) increases its affinity for alkaline developer and suppresses development defects. A structural unit (VI) having (x) an alkali-soluble group is A 1 is an oxygen atom and W 1 It is particularly preferable that the group is a 1,1,1,3,3,3-hexafluoro-2,2-methanediyl group.

[0158] If structural unit (VI) has an alkali-dissociable group (y), R F A is a monovalent organic group having 1 to 30 carbon atoms. 1 is an oxygen atom, -NR aa -, -COO-*, -OCO-*, or -SO2O-*. aa * is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. F This shows the site of binding. 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 If is -COO-*, -OCO-*, or -SO2O-*, then W 1 or R F is A 1 It has a fluorine atom on the carbon atom bonded to it or on an adjacent carbon atom. 1 If is an oxygen atom, then W 1 , R E It is a single bond, R D R is a hydrocarbon group with 1 to 20 carbon atoms. E It is a structure in which a carbonyl group is bonded to the terminal end, R F is an organic group containing a fluorine atom. When s is 2 or 3, multiple R E , W 1 , A 1 and R FThese may be the same or different. The presence of (y) an alkali-dissociable group in structural unit (VI) causes the resist film surface to change from hydrophobic to hydrophilic during the alkali development process. As a result, the affinity for the developer is significantly increased, and development defects can be suppressed more efficiently. Examples of structural unit (VI) having (y) an alkali-dissociable group include A 1 is -COO-*, R F Or W 1 Alternatively, it is particularly preferable that both of these contain fluorine atoms.

[0159] R C From the viewpoint of copolymerizability of the monomer that gives structural unit (VI), hydrogen atoms and methyl groups are preferred, and methyl groups are more preferred.

[0160] R E When the group is a divalent organic group, a group having a lactone structure is preferred, a group having a polycyclic lactone structure is more preferred, and a group having a norbornane lactone structure is even more preferred.

[0161] When a high-fluorine-content resin has structural units (VI), the content of structural units (VI) is preferably 40 mol%, more preferably 50 mol%, and even more preferably 55 mol%, relative to the total structural units constituting the high-fluorine-content resin. Furthermore, the upper limit of the above content is preferably 95 mol%, more preferably 90 mol%, and even more preferably 85 mol%. By setting the content of structural units (VI) within the above range, the water repellency of the resist film during immersion exposure can be further improved.

[0162] [Other structural units] The high-fluorine-content resin may include structural units other than those listed above, such as structural units (II) and (III) in the base resin, as well as structural units having an alicyclic structure represented by formula (6).

[0163] When a high-fluorine content resin contains structural unit (II) or structural unit (III), the content ratio of each structural unit in the high-fluorine content resin can preferably be the same as the content ratio described for the base resin.

[0164] When a high-fluorine-content resin contains structural units having the above-mentioned alicyclic structure, the content of these structural units is preferably 10 mol%, more preferably 20 mol%, and even more preferably 30 mol%, relative to the total structural units constituting the high-fluorine-content resin. Furthermore, the upper limit of the above content is preferably 60 mol%, more preferably 50 mol%, and even more preferably 45 mol%.

[0165] The lower limit of Mw for the high-fluorine-content resin is preferably 2,000, more preferably 4,000, even more preferably 6,000, and particularly preferably 8,000. The upper limit of Mw is preferably 30,000, more preferably 20,000, even more preferably 12,000, and particularly preferably 10,000.

[0166] The lower limit of the Mw / Mn ratio for high-fluorine-content resins is usually 1, with 1.1 being more preferable. The upper limit of the above Mw / Mn ratio is usually 5, with 3 being preferable, and 2 being more preferable.

[0167] If the radiation-sensitive resin composition contains a high-fluorine content resin, the amount of the high-fluorine content resin is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 1.5 parts by mass or more, and particularly preferably 2 parts by mass or more, per 100 parts by mass of the base resin. Furthermore, it 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 6 parts by mass or less.

[0168] By setting the content of the high-fluorine resin within the above range, the high-fluorine resin can be more effectively distributed to 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 enhanced. Furthermore, the surface modification of the resist film and the distribution of its internal composition during EUV exposure can be controlled to a high degree. The radiation-sensitive resin composition may contain one or more high-fluorine resins.

[0169] (Method for synthesizing high-fluorine content resins) High-fluorine-content resins can be synthesized by the same method as the base resin synthesis method described above.

[0170] (Acid diffusion control agent) The radiation-sensitive resin composition may optionally contain an acid diffusion control agent. The acid diffusion control agent controls the diffusion phenomenon of the acid generated from the onium salt compound (1) upon exposure in the resist film, and has the effect of suppressing undesirable chemical reactions in the unexposed areas. Furthermore, the storage stability of the resulting radiation-sensitive resin composition is improved. In addition, the resolution of the resist pattern is further improved, and changes in the line width of the resist pattern due to variations in the holding time from exposure to development can be suppressed, resulting in a radiation-sensitive resin composition with excellent process stability.

[0171] Examples of acid diffusion control agents include compounds represented by the following formula (7) (hereinafter also referred to as "nitrogen-containing compounds (I)"), compounds having two nitrogen atoms in the same molecule (hereinafter also referred to as "nitrogen-containing compounds (II)"), compounds having three nitrogen atoms (hereinafter also referred to as "nitrogen-containing compounds (III)"), amide group-containing compounds, urea compounds, nitrogen-containing heterocyclic compounds, and the like.

[0172] [ka]

[0173] In equation (7) above, R 22 , R 23 and R 24Each of these is 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.

[0174] Examples of nitrogen-containing compounds (I) include monoalkylamines such as n-hexylamine; dialkylamines such as di-n-butylamine; trialkylamines such as triethylamine; and aromatic amines such as aniline and 2,6-di-i-propylaniline.

[0175] Examples of nitrogen-containing compounds (II) include ethylenediamine and N,N,N',N'-tetramethylethylenediamine.

[0176] Examples of nitrogen-containing compounds (III) include polyamine compounds such as polyethyleneimine and polyallylamine; and polymers such as dimethylaminoethylacrylamide.

[0177] Examples of amide group-containing compounds include formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, benzamide, pyrrolidone, and N-methylpyrrolidone.

[0178] Examples of urea compounds include urea, methyl urea, 1,1-dimethyl urea, 1,3-dimethyl urea, 1,1,3,3-tetramethyl urea, 1,3-diphenyl urea, and tributylthiourea.

[0179] Examples of nitrogen-containing heterocyclic compounds include pyridines such as pyridine and 2-methylpyridine; morpholines such as N-propylmorpholine and N-(undecylcarbonyloxyethyl)morpholine; and pyrazines and pyrazoles.

[0180] Furthermore, compounds having an acid-dissociable group can also be used as the nitrogen-containing organic compound. Examples of nitrogen-containing organic compounds having an acid-dissociable group include Nt-butoxycarbonylpiperidine, Nt-butoxycarbonylimidazole, Nt-butoxycarbonylbenzimidazole, Nt-butoxycarbonyl-2-phenylbenzimidazole, Nt-amyloxycarbonyl-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-butoxycarbonyl-4-acetoxypiperidine, and Nt-amyloxycarbonyl-4-hydroxypiperidine.

[0181] Furthermore, a radiation-sensitive weak acid generator that generates a weak acid upon exposure can be suitably used as an acid diffusion control agent. The acid generated by the above-mentioned radiation-sensitive weak acid generator is a weak acid that does not induce the dissociation of the acid-dissociable groups in the resin under conditions that would normally cause the dissociation of those groups. In this specification, "dissociation" of an acid-dissociable group refers to dissociation that occurs when post-exposure baking is performed at 110°C for 60 seconds.

[0182] Examples of radiation-sensitive weak acid generators include onium salt compounds that decompose upon exposure and lose their ability to control acid diffusion. Examples of onium salt compounds include sulfonium salt compounds represented by the following formula (8-1) and iodonium salt compounds represented by the following formula (8-2). Also, examples include compounds containing a sulfonium cation and anion in the same molecule, represented by the following formula (8-3), and compounds containing an iodonium cation and anion in the same molecule, represented by the following formula (8-4).

[0183] [ka]

[0184] In the above equations (8-1) to (8-4), J + It is a sulfonium cation, U + This is an iodonium cation. + Examples of sulfonium cations represented by the above formulas (X-1) to (X-4) include U + Examples of iodonium cations represented by the above formulas (X-5) to (X-6) include iodonium cations represented by E - and Q - Each of them is independent of OH - , R α -COO - , R α -SO3 - This is an anion represented by R. α This refers to a single bond or a monovalent organic group having 1 to 30 carbon atoms. Examples of such organic groups include monovalent hydrocarbon groups having 1 to 20 carbon atoms, groups having a divalent heteroatom-containing group between carbon atoms or at the end of the carbon chain of the hydrocarbon group, groups in which some or all of the hydrogen atoms of the hydrocarbon group are replaced with a monovalent heteroatom-containing group, or combinations thereof.

[0185] Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms include monovalent linear hydrocarbon groups having 1 to 20 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms, or combinations thereof.

[0186] Examples of heteroatoms that constitute a divalent or monovalent heteroatom-containing group include oxygen, nitrogen, sulfur, phosphorus, silicon, and halogen atoms. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine atoms.

[0187] Examples of divalent heteroatom-containing groups include -CO-, -CS-, -NH-, -O-, -S-, -SO-, -SO2-, or combinations thereof.

[0188] Examples of monovalent heteroatom-containing groups include hydroxyl groups, sulfanyl groups, cyano groups, nitro groups, and halogen atoms.

[0189] Examples of the above-mentioned radiation-sensitive weak acid generating agent include compounds represented by the following formula.

[0190] [ka]

[0191] [ka]

[0192] Among the above-mentioned radiation-sensitive weak acid generating agents, sulfonium salts are preferred, triarylsulfonium salts are more preferred, and triphenylsulfonium salicylate and triphenylsulfonium 10-camphorsulfonate are even more preferred.

[0193] The lower limit of the acid diffusion control agent content is preferably 0.5 parts by mass, more preferably 1 part by mass, and even more preferably 2 parts by mass, per 100 parts by mass of the resin. The upper limit of the above content is preferably 30 parts by mass, more preferably 20 parts by mass, and even more preferably 15 parts by mass.

[0194] By setting the content of the acid diffusion control agent 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 control agents.

[0195] (solvent) The radiation-sensitive resin composition according to this embodiment contains a solvent. The solvent is not particularly limited as long as it is capable of dissolving or dispersing at least the onium salt compound (1) and the resin, as well as optionally contained acid diffusion control agents, etc.

[0196] Examples of solvents include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

[0197] Examples of alcohol-based solvents include, Monoalcohol solvents with 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 with 2 to 18 carbon atoms, such as ethylene glycol, 1,2-propylene glycol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol; Examples include polyhydric alcohol partial ether solvents, in which some of the hydroxyl groups of the above-mentioned polyhydric alcohol solvents have been etherified.

[0198] Examples of ether-based 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 (methylphenyl ether); Examples include polyhydric alcohol ether solvents, which are obtained by etherifying the hydroxyl groups of the above-mentioned polyhydric alcohol solvents.

[0199] Examples of ketone solvents include chain-like ketone solvents such as acetone, butanone, and methyl-iso-butyl ketone: Cyclopentanone, cyclohexanone, methylcyclohexanone, and other cyclic ketone solvents: Examples include 2,4-pentanedione, acetonylacetone, and acetophenone.

[0200] Examples of amide solvents include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; Examples include chain-like amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0201] 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-based solvents such as γ-butyrolactone and valerolactone; Carbonate-based solvents such as diethyl carbonate, ethylene carbonate, and propylene carbonate; Examples of polycarboxylic acid diester solvents include propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoacetate, and diethyl phthalate.

[0202] Examples of hydrocarbon solvents include, for example, Aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; Examples include aromatic hydrocarbon solvents such as benzene, toluene, di-iso-propylbenzene, and n-amylnaphthalene.

[0203] Among these, ester solvents and ether solvents are preferred, polyhydric alcohol partial ether acetate solvents, lactone solvents, monocarboxylic acid ester solvents, and ketone solvents are more preferred, and propylene glycol monomethyl ether acetate, γ-butyrolactone, ethyl lactate, and cyclohexanone are even more preferred. The radiation-sensitive resin composition may contain one or more solvents.

[0204] (Other optional components) The above-mentioned radiation-sensitive resin composition may contain other optional components in addition to the components listed above. Examples of these other optional components include crosslinking agents, segregation promoters, surfactants, alicyclic skeleton-containing compounds, sensitizers, and the like. These other optional components may be used individually or in combination of two or more types.

[0205] <Method for preparing a radiation-sensitive resin composition> The above radiation-sensitive resin composition can be prepared, for example, by mixing an onium salt compound (1), a resin, and optionally an acid diffusion control agent, a high-fluorine content resin, and a solvent in predetermined proportions. After mixing, the above radiation-sensitive resin composition is preferably filtered using a filter with a pore size of approximately 0.05 μm to 0.40 μm. The solid content concentration of the above radiation-sensitive resin composition is usually 0.1% to 50% by mass, preferably 0.5% to 30% by mass, and more preferably 1% to 20% by mass.

[0206] <Pattern Formation Method> A pattern forming method according to one embodiment of the present invention is: The above radiation-sensitive resin composition is applied directly or indirectly to a substrate to form a resist film (1) (hereinafter also referred to as the "resist film formation step"), The above resist film is exposed in step (2) (hereinafter also referred to as the "exposure step"), The process includes (3) developing the exposed resist film (hereinafter also referred to as the "development step").

[0207] According to the pattern formation method described above, a high-quality resist pattern can be formed because the above-mentioned radiation-sensitive resin composition is used, which is capable of forming a resist film with excellent sensitivity, LWR performance, DOF performance, pattern rectangularity, CDU performance, and pattern circularity in the exposure process. The following describes each step.

[0208] [Resist film formation process] In this step (step (1) above), a resist film is formed using the radiation-sensitive resin composition. Examples of substrates for forming this resist film include conventionally known materials such as silicon wafers, silicon dioxide wafers, and aluminum-coated wafers. Alternatively, an organic or inorganic anti-reflective film, such as those disclosed in Japanese Patent Publication No. 6-12452 or Japanese Patent Publication No. 59-93448, may be formed on the substrate. Examples of coating methods include spin coating, casting, and roll coating. After coating, pre-baking (PB) may be performed as needed to volatilize the solvent in the coating film. The PB temperature is usually 60°C to 140°C, with 80°C to 130°C being preferred. The PB time is usually 5 seconds to 600 seconds, with 10 seconds to 300 seconds being preferred.

[0209] The lower limit of the thickness of the formed resist film is preferably 10 nm, more preferably 20 nm, and even more preferably 30 nm. The upper limit of the thickness is preferably 500 nm, more preferably 400 nm, and even more preferably 300 nm. In particular, when a thick resist film is exposed to ArF excimer laser light in the exposure process described later, the lower limit of the thickness may be 100 nm, 150 nm, or 200 nm.

[0210] When performing immersion exposure, regardless of the presence or absence of water-repellent polymer additives such as the high-fluorine-content resin in the above-mentioned radiation-sensitive resin composition, a protective immersion film insoluble in the immersion liquid may be provided on the formed resist film to avoid direct contact between the immersion liquid and the resist film. As the protective immersion film, either a solvent-peelable protective film that is peeled off with a solvent before the development process (see, for example, Japanese Patent Application Publication No. 2006-227632) or a developer-peelable protective film that is peeled off simultaneously with development in the development process (see, for example, Japanese Patent Application Publication Nos. WO2005-069076 and WO2006-035790) may be used. However, from the viewpoint of throughput, it is preferable to use a developer-peelable protective immersion film.

[0211] Furthermore, when the subsequent exposure process is carried out with radiation of a wavelength of 50 nm or less, it is preferable to use a resin having structural unit (II) and structural unit (IV) as the base resin in the above composition.

[0212] [Synthesis process] In this step (step (2) above), the resist film formed in the resist film formation step (1) above is exposed by irradiating it with radiation through a photomask (and, in some cases, through an immersion liquid such as water). The radiation used for exposure can be electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV (extreme ultraviolet light), X-rays, and gamma rays, depending on the line width of the desired pattern; or charged particle beams such as electron beams and alpha rays. 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 exposure is performed by immersion lithography, the immersion liquid used can be, for example, water or a fluorinated inert liquid. The immersion liquid is preferably transparent to the exposure wavelength and has the smallest possible temperature coefficient of refractive index to minimize distortion of the optical image projected onto the film. In particular, when the exposure light source is ArF excimer laser light (wavelength 193 nm), in addition to the above considerations, water is preferred due to its availability and ease of handling. When water is used, a small amount of an additive that reduces the surface tension of the water and increases its surfactant properties may be added. This additive is preferably one that does not dissolve the resist film on the wafer and has negligible effect on the optical coating on the underside of the lens. Distilled water is preferred as the water used.

[0214] After the exposure described above, it is preferable to perform a post-exposure bake (PEB) to promote the dissociation of acid-dissociable groups in the resin, etc., by the acid generated from the radiation-sensitive acid generator during exposure in the exposed portion of the resist film. This PEB creates a difference in solubility in the developer between the exposed and unexposed portions. The PEB temperature is usually 50°C to 180°C, with 80°C to 130°C being preferred. The PEB time is usually 5 seconds to 600 seconds, with 10 seconds to 300 seconds being preferred.

[0215] [Development process] In this step (step (3) above), the resist film exposed in the exposure step (step (2) above) is developed. This allows a predetermined resist pattern to be formed. After development, it is common to wash with a rinsing solution such as water or alcohol and then dry it.

[0216] Examples of developers used in the above development process include, in the case of alkaline development, an alkaline aqueous solution containing at least one alkaline compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, or 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, an aqueous TMAH solution is preferred, and a 2.38% by mass aqueous TMAH solution is more preferred.

[0217] Furthermore, in the case of organic solvent development, examples of organic solvents include hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents, or solvents containing organic solvents. Examples of the above organic solvents include one or more of the solvents listed above as solvents for the radiation-sensitive resin composition. Among these, ether solvents, ester solvents, and ketone solvents are preferred. As for ether solvents, glycol ether solvents are preferred, and ethylene glycol monomethyl ether and propylene glycol monomethyl ether are more preferred. As for ester solvents, acetate ester solvents are preferred, and n-butyl acetate and amyl acetate are more preferred. As for ketone solvents, chain ketones are preferred, and 2-heptanone is more preferred. The content of organic solvents 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 organic solvents in the developer include water and silicone oil.

[0218] As mentioned above, either an alkaline developer or an organic solvent developer may be used as the developer. The appropriate choice can be made depending on whether a positive or negative pattern is desired.

[0219] Examples of development methods include immersing the substrate in a tank filled with developer solution for a certain period of time (dip method), developing by piling up the developer solution on the substrate surface using surface tension and letting it remain still for a certain period of time (paddle method), spraying the developer solution onto the substrate surface (spray method), and continuously dispensing the developer solution while scanning a developer solution dispensing nozzle at a constant speed onto a substrate rotating at a constant speed (dynamic dispensing method).

[0220] <Radiation-sensitive acid generator> The radiation-sensitive acid generator according to this embodiment consists of an onium salt compound represented by the following formula (1). [ka] (In formula (1), R 1 , R 2 and R 3 Each of these is independently a monovalent organic group having 1 to 10 carbon atoms, or R 1 , R 2 and R 3 R represents a monovalent or divalent group containing a cyclic structure with 3 to 20 carbon atoms, formed by combining two or three of these atoms with the carbon atoms to which they are bonded. 1 , R 2 and R 3 If two of them constitute the above cyclic structure, the remaining one is a monovalent organic group with 1 to 10 carbon atoms. R 4 and R 5 Each of these is independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group, or a monovalent fluorinated hydrocarbon group. 4 and R 5 If multiple R 4 and R 5 They are either the same or different. R 6 , R 7 and R 8 Each of these is independently a fluorine atom or a monovalent fluorinated hydrocarbon group. m1 is an integer between 0 and 8. Z + (This is a monovalent, radiation-sensitive onium cation.)

[0221] As the onium salt compound represented by the above formula (1), the onium salt compound (1) in the radiation-sensitive resin composition can be suitably adopted. [Examples]

[0222] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. The methods for measuring various physical properties are shown below.

[0223] [Weight-average molecular weight (Mw) and number-average molecular weight (Mn)] The Mw and Mn of the resin were measured under the conditions described above. The degree of dispersion (Mw / Mn) was calculated from the measured Mw and Mn values.

[0224] [ 13 C-NMR analysis] resin 13 ¹

[0225] <Synthesis of resins> The monomers used in the synthesis of each resin in each example and comparative example are shown below. In the following synthesis examples, unless otherwise specified, parts by mass refers to the value when the total mass of the monomers used is 100 parts by mass, and mol% refers to the value when the total number of moles of the monomers used is 100 mol%.

[0226] [ka]

[0227] [Synthesis Example 1] (Synthesis of resin (A-1)) Monomers (M-1), (M-4), (M-6), (M-18), and (M-22) were dissolved in 200 parts by mass of 2-butanone in a molar ratio of 40 / 10 / 20 / 20 / 10 (mol%). AIBN (azobisisobutyronitrile) (6 mol% relative to the total 100 mol% of the monomers used) was added as an initiator to prepare the monomer solution. 100 parts by mass of 2-butanone was placed in a reaction vessel, and after purging with nitrogen for 30 minutes, the reaction vessel was heated to 80°C. The monomer solution was then added dropwise over 3 hours while stirring. The start of the dropwise addition was defined 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 to below 30°C by water cooling. The cooled polymerization solution was added to methanol (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with methanol, filtered again, and dried at 50°C for 24 hours to obtain a white powdery resin (A-1) (yield: 80%). The Mw of resin (A-1) was 5,500, and the Mw / Mn ratio was 1.61. 13 ¹³C-NMR analysis revealed that the content of each structural unit derived from (M-1), (M-4), (M-6), (M-18), and (M-22) was 40.3 mol%, 7.8 mol%, 20.1 mol%, 19.8 mol%, and 12.0 mol%, respectively.

[0228] [Synthesis Examples 2-17] (Synthesis of resins (A-2) to (A-17)) Resins (A-2) to (A-17) were synthesized in the same manner as in Synthesis Example 1, except that the monomers used were of the types and proportions shown in Table 1 below. The content percentage (mol%) and physical properties (Mw and Mw / Mn) of each structural unit of the obtained resins are also shown in Table 1 below. In Table 1 below, "-" indicates that the corresponding monomer was not used (the same applies to subsequent tables).

[0229] [Table 1]

[0230] [Synthesis Example 18] (Synthesis of resin (A-18)) Monomers (M-1), (M-5), and (M-20) were dissolved in 1-methoxy-2-propanol (200 parts by mass) in a molar ratio of 40 / 30 / 30 (mol%), and AIBN (5 mol%) was added as an initiator to prepare monomer solutions. 100 parts by mass of 1-methoxy-2-propanol 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 solutions were added dropwise over 3 hours while stirring. The start of the dropwise addition was defined 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 to below 30°C by water cooling. The cooled polymerization solution was added to hexane (2,000 parts by mass), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane, filtered again, 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 with stirring. After the reaction was complete, the residual solvent was removed by distillation, and the obtained solid was dissolved in acetone (100 parts by mass) and added dropwise to water (500 parts by mass) to solidify the resin. The obtained solid was filtered off and dried at 50°C for 13 hours to obtain a white powdered resin (A-18) (yield: 81%). The Mw of resin (A-18) was 5,500, and the Mw / Mn ratio was 1.59. 13 1C-NMR analysis revealed that the content of each structural unit derived from (M-1), (M-5), and (M-20) was 40.5 mol%, 29.6 mol%, and 29.9 mol%, respectively.

[0231] [Synthesis Examples 19-24] (Synthesis of resins (A-19) to (A-24)) Resins (A-19) to (A-24) were synthesized in the same manner as in Synthesis Example 18, except that the monomers used were of the types and proportions shown in Table 2 below. Note that the monomers that give structural unit (IV) in the polymer were... 13¹¹C-NMR measurements confirmed the disappearance of the carbonyl group peak of the acetyl group, indicating that virtually all alkali-dissociable groups had been hydrolyzed to phenolic hydroxyl groups. The content percentage (mol%) and physical properties (Mw and Mw / Mn) of each structural unit of the obtained resin are shown in Table 2 below.

[0232] [Table 2]

[0233] [Synthesis Example 25] (Synthesis of high-fluorine content resin (F-1)) Monomers (M-2), (M-22), and (M-26) were dissolved in 200 parts by mass of 2-butanone in a molar ratio of 20 / 10 / 70 (mol%), and AIBN (3 mol%) was added as an initiator to prepare monomer solutions. 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 solutions were added dropwise over 3 hours while stirring. The start of the dropwise addition was defined 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 to below 30°C by water cooling. The solvent was replaced with acetonitrile (400 parts by mass), and hexane (100 parts by mass) was added and stirred, and the acetonitrile layer was recovered. This process was repeated three times. By replacing the solvent with propylene glycol monomethyl ether acetate, a solution of high-fluorine-content resin (F-1) was obtained (yield: 73%). The Mw of the high-fluorine-content resin (F-1) was 9,800, and the Mw / Mn ratio was 1.79. Furthermore, 13 ¹³C-NMR analysis revealed that the content of each structural unit derived from (M-2), (M-22), and (M-26) was 18.3 mol%, 10.7 mol%, and 71.0 mol%, respectively.

[0234] [Synthesis Examples 26-29] (Synthesis of high-fluorine content resins (F-2) to high-fluorine content resins (F-5)) High-fluorine-content resins (F-2) to (F-5) were synthesized in the same manner as in Synthesis Example 25, except that monomers of the types and proportions shown in Table 3 below were used. The content percentage (mol%) and physical properties (Mw and Mw / Mn) of each structural unit of the obtained high-fluorine-content resins are shown in accordance with Table 3 below.

[0235] [Table 3]

[0236] [B] Synthesis of radiation-sensitive acid generators [Example B1] (Synthesis of onium salt compound (B-1)) [B] An onium salt compound (B-1) as a radiation-sensitive acid generator was synthesized according to the following synthesis scheme.

[0237] [ka]

[0238] In a reaction vessel, 20.0 mmol of 4-bromo-3,3,4,4-tetrafluorobutan-1-ol was mixed with acetonitrile and water (1:1 by mass) to make a 1 M solution. Then, 40.0 mmol of sodium dithionite and 60.0 mmol of sodium bicarbonate were added, and the mixture was reacted at 70°C for 4 hours. After extraction with acetonitrile and removal of the solvent, a mixture of acetonitrile and water (3:1 by mass) was added to make a 0.5 M solution. 60.0 mmol of hydrogen peroxide and 2.00 mmol of sodium tungstate were added, and the mixture was heated and stirred at 50°C for 12 hours. The sodium sulfonate salt compound was obtained by extraction with acetonitrile and removal of the solvent. 20.0 mmol of triphenylsulfonium bromide was added to the above sodium sulfonate salt compound, and a mixture of water and dichloromethane (1:3 by mass) was added to make a 0.5 M solution. After vigorous stirring at room temperature for 3 hours, dichloromethane was added for extraction, and the organic layer was separated. The obtained organic layer was dried over sodium sulfate, the solvent was removed by distillation, and the onium salt was purified by column chromatography to obtain the salt in good yield.

[0239] 20.0 mmol of 1-adamantanol, 30.0 mmol of concentrated sulfuric acid, and 50 g of toluene were added to the above onium salt and the mixture was stirred at 100°C for 10 hours. Then, saturated sodium bicarbonate aqueous solution was added to stop the reaction, and methylene chloride was added for extraction, separating the organic layer. The obtained organic layer was washed with saturated sodium chloride aqueous solution, and then with water. After drying with sodium sulfate, the solvent was removed by distillation, and the compound was purified by column chromatography to obtain the onium salt compound (B-1) represented by the above formula (B-1) in good yield.

[0240] [Examples B2-B14] (Synthesis of onium salt compounds (B-2) to (B-14)) Except for appropriately changing the raw materials and precursors, onium salt compounds as radiation-sensitive acid generators represented by the following formulas (B-2) to (B-14) were synthesized in the same manner as in Example B1.

[0241] [ka]

[0242] In addition to the synthesized components mentioned above, the following compounds were used.

[0243] [Radiation-sensitive acid generators other than (B-1) to (B-14)] b-1 to b-11: Compounds represented by the following formulas (b-1) to (b-11) (Hereafter, compounds represented by formulas (b-1) to (b-11) may be referred to as "compound (b-1)" to "compound (b-11)," respectively.)

[0244] [ka]

[0245] [[D] Acid diffusion control agent] D-1 to D-7: Compounds represented by the following formulas (D-1) to (D-7).

[0246] [Chemical]

[0247] [[E] Solvent] E-1: Propylene glycol monomethyl ether acetate E-2: Cyclohexanone E-3: γ-Butyrolactone E-4: Ethyl lactate

[0248] [Preparation of Positive Radiation-Sensitive Resin Composition for ArF Immersion Lithography] [Example 1] [A] 100 parts by mass of (A-1) as resin, 12.0 parts by mass of (B-1) as radiation-sensitive acid generator, 5.0 parts by mass of (D-1) as acid diffusion controller, 5.0 parts by mass (solid content) of (F-1) as high fluorine content resin, and 3,400 parts by mass of mixed solvent of (E-1) / (E-2) / (E-3) as [E] 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-1).

[0249] [Examples 2 to 42 and Comparative Examples 1 to 10] Except for using each component of the types and contents shown in Table 4 below, the radiation-sensitive resin compositions (J-2) to (J-42) and (CJ-1) to (CJ-10) were prepared in the same manner as in Example 1.

[0250] [Table 4]

[0251] [Formation of Resist Pattern Using Positive Radiation-Sensitive Resin Composition for ArF Immersion Lithography] On a 12-inch silicon wafer, a base layer anti-reflective coating composition (Brewer Science's "ARC66") was applied using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"), and then heated at 205°C for 60 seconds to form a base layer anti-reflective coating with an average thickness of 100 nm. On this base layer anti-reflective coating, the ArF exposure positive-type radiation-sensitive resin composition prepared above was applied using the same spin coater, and pre-bake (PB) was performed at 100°C for 60 seconds. Subsequently, a resist film with an average thickness of 150 nm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed using an ArF excimer laser immersion lithography system (ASML's "TWINSCAN XT-1900i") under optical conditions of NA=1.35 and Dipole (σ=0.9 / 0.7) through a 60 nm line-and-space mask pattern. After exposure, post-exposure baking (PEB) was performed at 100°C for 60 seconds. Subsequently, the resist film was alkaline developed using a 2.38% by mass aqueous TMAH solution as the alkaline developer. After development, it was washed with water and then dried to form a positive-type resist pattern (60 nm line and space pattern).

[0252] <Rating> The sensitivity, LWR performance, DOF performance, and pattern rectangularity of resist patterns formed using the above-mentioned positive-type radiation-sensitive resin composition for ArF immersion lithography were evaluated according to the following methods. The results are shown in Table 5 below. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000") was used to measure the length of the resist patterns. The results are shown in Table 5 below.

[0253] [sensitivity] In forming a resist pattern using the above-mentioned positive-type radiation-sensitive resin composition for ArF immersion lithography, the exposure amount for forming a 60 nm line-and-space pattern is defined as the optimal exposure amount, and this optimal exposure amount is set to the sensitivity (mJ / cm²). 2 The sensitivity was set to 35 mJ / cm². 2 The following cases are considered "good" and 35 mJ / cm². 2 If it exceeded this value, it was rated as "poor."

[0254] [LWR performance] A 60nm line-and-space resist pattern was formed by irradiating with the optimal exposure dose determined in the sensitivity evaluation described above. The formed resist pattern was observed from the top using the scanning electron microscope described above. Line width variation was measured at a total of 500 points, and the 3-sigma value was determined from the distribution of these measurements. This 3-sigma value was defined as LWR (nm). A smaller LWR value indicates less line roughness and better performance. LWR performance was evaluated as "good" if it was 3.5nm or less, and "poor" if it was greater than 3.5nm.

[0255] [DOF performance] Following the method used for measuring sensitivity, a mask with dimensions such that the line width of the formed line-and-space pattern (1L1S) is 60 nm was used, and the depth of focus (DOF) range in which the line width of the space in the formed line-and-space pattern is between 50 nm and 70 nm was measured. DOF performance was evaluated as "good" if it was 150 nm or higher, and "poor" if it was below 150 nm.

[0256] [Pattern Rectangle] The 60nm line-and-space resist patterns formed by irradiating with the optimal exposure dose determined in the sensitivity evaluation above were observed using the scanning electron microscope described above, and the cross-sectional shape of the line-and-space patterns was evaluated. The rectangularity of the resist pattern was evaluated as follows: if the ratio of the length of the lower side to the length of the upper side in the cross-sectional shape was 1 or more and 1.05 or less, it was evaluated as "A" (excellent); if it was greater than 1.05 and 1.10 or less, it was evaluated as "B" (good); and if it was greater than 1.10, it was evaluated as "C" (poor).

[0257] [Table 5]

[0258] As is clear from the results in Table 5, the radiation-sensitive resin composition of the example had good sensitivity, LWR performance, DOF performance, and pattern rectangularity when used in ArF immersion exposure. In contrast, in the comparative examples, each characteristic was inferior to that of the example. Therefore, when the radiation-sensitive resin composition of the example is used in ArF immersion exposure, a resist pattern with high sensitivity and good LWR performance, DOF performance, and pattern rectangularity can be formed.

[0259] [Preparation of Positive-Type Radiation-Sensitive Resin Composition for ArF-Dry Exposure] [Example 43] [A] 100 parts by mass of (A-1) as a resin, [B] 10.0 parts by mass of (B-1) as a radiation-sensitive acid generator, [D] 3.0 parts by mass of (D-6) as an acid diffusion controller, and 3,230 parts by mass of a mixed solvent of (E-1) / (E-2) / (E-3) as [E] 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-43).

[0260] [Examples 44 to 50 and Comparative Examples 11 to 12] Except for using the components of the types and contents shown in Table 6 below, in the same manner as in Example 43, radiation-sensitive resin compositions (J-44) to (J-50) and (CJ-11) to (CJ-12) were prepared.

[0261]

Table 6

[0262] [Formation of Resist Pattern Using Positive-Type Radiation-Sensitive Resin Composition for ArF-Dry Exposure] On an 8-inch silicon wafer, a base layer anti-reflective coating composition (Brewer Science's "ARC29") was applied using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT8"), and then heated at 205°C for 60 seconds to form a base layer anti-reflective coating with an average thickness of 77 nm. On this base layer anti-reflective coating, the ArF-Dry exposure positive-type radiation-sensitive resin composition prepared above was applied using the same spin coater, and pre-bake (PB) was performed at 100°C for 60 seconds. Subsequently, a resist film with an average thickness of 300 nm was formed by cooling at 23°C for 30 seconds. Next, a resist pattern with a line width of 90 nm line and space was formed on this resist film using an ArF excimer laser exposure system (Nikon's "S306C") under optical conditions of NA=0.75 and Annular (σ=0.8 / 0.6). After exposure, post-exposure bake (PEB) was performed at 100°C for 60 seconds. Subsequently, the resist film was alkaline-developed using a 2.38% by mass aqueous TMAH solution as the alkaline developer. After development, it was washed with water and then dried to form a positive-type resist pattern (a 90 nm line-and-space resist pattern).

[0263] <Rating> The sensitivity, LWR performance, DOF performance, and pattern rectangularity of resist patterns formed using the above-mentioned positive-type radiation-sensitive resin composition for ArF-Dry exposure were evaluated according to the following methods. The results are shown in Table 7 below. A scanning electron microscope (Hitachi High-Technologies Corporation's "S-9380") was used to measure the length of the resist patterns.

[0264] [sensitivity] In forming a resist pattern using the above-mentioned positive-type radiation-sensitive resin composition for ArF-Dry exposure, the exposure amount for forming a 90nm line-and-space pattern is defined as the optimal exposure amount, and this optimal exposure amount is set to the sensitivity (mJ / cm²). 2 The sensitivity was set to 35 mJ / cm². 2 The following cases are considered "good" and 35 mJ / cm². 2 If it exceeded this value, it was rated as "poor."

[0265] [LWR performance] A 90nm line-and-space resist pattern was formed by irradiating with the optimal exposure dose determined in the sensitivity evaluation described above. The formed resist pattern was observed from the top using the scanning electron microscope described above. Line width variation was measured at a total of 500 points, and the 3-sigma value was determined from the distribution of these measurements. This 3-sigma value was defined as LWR (nm). A smaller LWR value indicates less line roughness and better performance. LWR performance was evaluated as "good" if it was 4.0nm or less, and "poor" if it was greater than 4.0nm.

[0266] [DOF performance] Following the method used for measuring sensitivity, a mask with dimensions such that the line width of the formed line-and-space pattern (1L1S) is 90 nm was used, and the depth of focus (DOF) range in which the line width of the space in the formed line-and-space pattern is between 80 nm and 100 nm was measured. DOF performance was evaluated as "good" if it was 150 nm or higher, and "poor" if it was below 150 nm.

[0267] [Pattern Rectangle] The 90nm line-and-space resist patterns formed by irradiating with the optimal exposure dose determined in the sensitivity evaluation above were observed using the scanning electron microscope described above, and the cross-sectional shape of the line-and-space patterns was evaluated. The rectangularity of the resist pattern was evaluated as follows: if the ratio of the length of the lower side to the length of the upper side in the cross-sectional shape was 1 or more and 1.05 or less, it was "A" (excellent); if it was greater than 1.05 and 1.10 or less, it was "B" (good); and if it was greater than 1.10, it was "C" (poor).

[0268] [Table 7]

[0269] As is clear from the results in Table 7, the radiation-sensitive resin composition of the example had good sensitivity, LWR performance, DOF performance, and pattern rectangularity when used for ArF-Dry exposure. In contrast, in the comparative examples, each characteristic was inferior to that of the example. Therefore, when the radiation-sensitive resin composition of the example is used for ArF-Dry exposure, a resist pattern with high sensitivity and good LWR performance, DOF performance, and pattern rectangularity can be formed.

[0270] [Preparation of Positive-Type Radiation-Sensitive Resin Composition for Extreme Ultraviolet (EUV) Exposure] [Example 51] [A] 100 parts by mass of (A-18) as a resin, [B] 30.0 parts by mass of (B-1) as a radiation-sensitive acid generator, [D] 20.0 parts by mass of (D-2) as an acid diffusion controller, [F] 3.0 parts by mass (solid content) of (F-5) as a high fluorine content resin, and 6,110 parts by mass of a mixed solvent of (E-1) / (E-4) as a solvent were mixed and filtered through a membrane filter with a pore size of 0.2 μm to prepare a radiation-sensitive resin composition (J-51).

[0271] [Examples 52 to 60 and Comparative Examples 13 to 14] Except for using each component of the types and contents shown in Table 8 below, the radiation-sensitive resin compositions (J-52) to (J-60) and (CJ-13) to (CJ-14) were prepared in the same manner as in Example 51.

[0272]

Table 8

[0273] [Formation of Resist Pattern Using Positive-Type Radiation-Sensitive Resin Composition for EUV Exposure] On a 12-inch silicon wafer, a base layer anti-reflective coating composition (Brewer Science's "ARC66") was applied using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"), and then heated at 205°C for 60 seconds to form a base layer anti-reflective coating with an average thickness of 105 nm. The prepared positive-type radiation-sensitive resin composition for EUV exposure was applied to this base layer anti-reflective coating using the same spin coater, and PB was performed at 130°C for 60 seconds. Subsequently, a resist film with an average thickness of 60 nm was formed by cooling at 23°C for 30 seconds. Next, this resist film was exposed using an EUV exposure apparatus (ASML's "NXE3300") with NA=0.33, illumination conditions: Conventional s=0.89, and mask: imecDEFECT32FFR02. After exposure, PEB was performed at 120°C for 60 seconds. Subsequently, the resist film was alkaline-developed using a 2.38% by mass aqueous TMAH solution as the alkaline developer. After development, it was washed with water and then dried to form a positive-type resist pattern (30 nm line and space pattern).

[0274] <Rating> The sensitivity, LWR performance, and pattern rectangularity of resist patterns formed using the above-mentioned positive-type radiation-sensitive resin composition for EUV exposure were evaluated according to the following method. The results are shown in Table 9 below. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000") was used to measure the length of the resist patterns.

[0275] [sensitivity] In forming a resist pattern using the above-mentioned positive-type radiation-sensitive resin composition for EUV lithography, the exposure amount for forming a 30 nm line-and-space pattern is defined as the optimal exposure amount, and this optimal exposure amount is set to the sensitivity (mJ / cm²). 2 The sensitivity was set to 40 mJ / cm². 2 The following cases are considered "good" and 40 mJ / cm². 2 If it exceeded this value, it was rated as "poor."

[0276] [LWR performance] The mask size was adjusted to form a 30nm line-and-space pattern by irradiating with the optimal exposure amount determined in the sensitivity evaluation described above, and a resist pattern was formed. The formed resist pattern was observed from the top of the pattern using the scanning electron microscope described above. The line width variation was measured at a total of 500 points, and the 3-sigma value was determined from the distribution of these measurements. This 3-sigma value was defined as LWR (nm). A smaller LWR value indicates less line jaggedness and better performance. LWR performance was evaluated as "good" if it was 3.0nm or less, and "poor" if it was greater than 3.0nm.

[0277] [Pattern Rectangle] The 30nm line-and-space resist patterns formed by irradiating with the optimal exposure dose determined in the sensitivity evaluation above were observed using the scanning electron microscope described above, and the cross-sectional shape of the line-and-space patterns was evaluated. The rectangularity of the resist pattern was evaluated as follows: if the ratio of the length of the lower side to the length of the upper side in the cross-sectional shape was 1 or more and 1.05 or less, it was evaluated as "A" (excellent); if it was greater than 1.05 and 1.10 or less, it was evaluated as "B" (good); and if it was greater than 1.10, it was evaluated as "C" (poor).

[0278] [Table 9]

[0279] As is clear from the results in Table 9, the radiation-sensitive resin composition of the example showed good sensitivity, LWR performance, and pattern rectangularity when used in EUV exposure, whereas the comparative example exhibited inferior characteristics compared to the example.

[0280] [Preparation of negative-type radiation-sensitive resin composition for ArF exposure, formation and evaluation of resist patterns using this composition] [Example 61] A radiation-sensitive resin composition (J-61) was prepared by mixing [A] 100 parts by mass of (A-1) as a resin, [B] 8.0 parts by mass of (B-1) as a radiation-sensitive acid generator, [D] 5.0 parts by mass of (D-5) as an acid diffusion control agent, [F] 2.0 parts by mass (solids) of (F-3) as a high-fluorine-content resin, and [E] 3,230 parts by mass of a mixed solvent of (E-1) / (E-2) / (E-3) (mass ratio 2,240 / 960 / 30) as a solvent, and filtering the mixture through a membrane filter with a pore size of 0.2 μm.

[0281] On a 12-inch silicon wafer, a base layer anti-reflective coating composition (Brewer Science's "ARC66") was applied using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"), and then heated at 205°C for 60 seconds to form a base layer anti-reflective coating with an average thickness of 100 nm. On this base layer anti-reflective coating, the ArF exposure negative-type radiation-sensitive resin composition (J-61) prepared above was applied using the same spin coater, and pre-bake (PB) was performed at 100°C for 60 seconds. Subsequently, 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 using an ArF excimer laser immersion lithography system (ASML's "TWINSCAN XT-1900i") under optical conditions of NA=1.35 and Annular (σ=0.8 / 0.6) through a mask pattern with 50 nm holes and a 100 nm pitch. After exposure, post-exposure baking (PEB) was performed at 100°C for 60 seconds. Subsequently, the resist film was developed using n-butyl acetate as the organic solvent developer and dried to form a negative-type resist pattern (50 nm holes, 100 nm pitch contact hole pattern).

[0282] The sensitivity of the resist pattern using the above-mentioned ArF exposure negative-type radiation-sensitive resin composition was evaluated in the same manner as the evaluation of the resist pattern using the above-mentioned ArF exposure positive-type radiation-sensitive resin composition. In addition, the CDU performance and pattern circularity were evaluated according to the following methods.

[0283] [CDU performance] The optimal exposure dose determined in the sensitivity evaluation above was used to form 50 nm holes and 100 nm pitch contact holes. The formed resist pattern was observed from the top using the scanning electron microscope described above. The variation in contact hole diameter was measured at a total of 500 points, and the 3-sigma value was determined from the distribution of these measurements. This 3-sigma value was defined as CDU (nm). A smaller CDU value indicates less roughness and better performance of the holes. CDU performance was evaluated as "good" if it was less than 3.5 nm and "poor" if it was 3.5 nm or greater.

[0284] [Circular Pattern] The 50nm holes and 100nm pitch contact holes formed by irradiating with the optimal exposure amount determined in the sensitivity evaluation above were observed in plan view using the scanning electron microscope described above, and their vertical and horizontal sizes were measured. If the ratio of vertical size to horizontal size was 0.95 or more and less than 1.05, it was evaluated as "A" (excellent); if it was 0.90 or more and less than 0.95, or 1.05 or more and less than 1.10, it was evaluated as "B" (good); and if it was less than 0.90, or 1.10 or more, it was evaluated as "C" (poor).

[0285] As a result, the radiation-sensitive resin composition of Example 61 exhibited good sensitivity, CDU performance, and pattern circularity even when a negative-type resist pattern was formed by ArF exposure.

[0286] [Preparation of negative-type radiation-sensitive resin composition for EUV exposure, formation and evaluation of resist patterns using this composition] [Example 62] A radiation-sensitive resin composition (J-62) was prepared by mixing [A] 100 parts by mass of (A-18) as a resin, [B] 25.0 parts by mass of (B-9) as a radiation-sensitive acid generator, [D] 10.0 parts by mass of (D-4) as an acid diffusion control agent, [F] 5.0 parts by mass of (F-5) as a high-fluorine-content resin (solids), and [E] 6,110 parts by mass (mass ratio 4,280 / 1,830) of a mixed solvent of (E-1) / (E-4) as a solvent, and filtering the mixture through a membrane filter with a pore size of 0.2 μm.

[0287] On a 12-inch silicon wafer, a base layer anti-reflective coating composition (Brewer Science's "ARC66") was applied using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"), and then heated at 205°C for 60 seconds to form a base layer anti-reflective coating with an average thickness of 105 nm. On this base layer anti-reflective coating, the prepared EUV exposure negative-type radiation-sensitive resin composition (J-62) was applied using the same spin coater, and PB was performed at 130°C for 60 seconds. Subsequently, 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 using an EUV exposure apparatus (ASML's "NXE3300") with NA=0.33, illumination conditions: Conventional s=0.89, and mask: imecDEFECT32FFR15. After exposure, PEB was performed at 120°C for 60 seconds. Subsequently, the resist film was developed using n-butyl acetate as the organic solvent developer and dried to form a negative-type resist pattern (a contact hole pattern with 20 nm holes and a 40 nm pitch).

[0288] The resist patterns using the above-mentioned negative-type radiation-sensitive resin composition for EUV exposure were evaluated in the same manner as the resist patterns using the above-mentioned negative-type radiation-sensitive resin composition for ArF exposure. As a result, the radiation-sensitive resin composition of experiment 62 showed good sensitivity, CDU performance, and pattern circularity even when negative-type resist patterns were formed by EUV exposure. [Industrial applicability]

[0289] The radiation-sensitive resin composition, pattern formation method, and radiation-sensitive acid generator described above enable the formation of resist patterns that exhibit good sensitivity to exposure light and have excellent LWR performance, DOF performance, pattern rectangularity, CDU performance, and pattern circularity. Therefore, these can be suitably used in semiconductor device processing processes and the like, where further miniaturization is expected in the future.

Claims

1. An onium salt compound represented by the following formula (1), A resin containing structural unit (I) represented by the following formula (2), Solvent and A radiation-sensitive resin composition containing [a specific substance]. 【Chemistry 1】 (In formula (1), R1, R2, and R3 are substituted or unsubstituted monovalent linear hydrocarbon groups having 1 to 10 carbon atoms. Of R1, R2, and R3, two are substituted or unsubstituted monovalent linear hydrocarbon groups having 1 to 10 carbon atoms, and the remaining one is a monovalent organic group having 3 to 10 carbon atoms containing a cyclic hydrocarbon structure (however, no ester bonds are bonded to the carbon atoms to which R1, R2, and R3 are bonded in formula (1) above). Two of R1, R2, and R3 are a divalent alicyclic hydrocarbon group having 5 to 20 carbon atoms, formed by combining them with the carbon atoms to which they are bonded; a group in which some or all of the hydrogen atoms contained in the alicyclic hydrocarbon group are substituted with substituents; or a group containing SO2 between carbon atoms (including between two adjacent carbon atoms and between two non-adjacent carbon atoms), and the remaining one is a substituted or unsubstituted monovalent linear hydrocarbon group having 1 to 10 carbon atoms, or R1, R2, and R3 are monovalent alicyclic hydrocarbon groups having 6 to 20 carbon atoms that can be combined with each other and formed together with the carbon atoms to which they are bonded, groups in which some or all of the hydrogen atoms contained in the alicyclic hydrocarbon group are replaced with substituents, or groups that contain CO, O, or a combination of two or more of these in the carbon-carbon spaces (including between two adjacent carbon atoms and between two non-adjacent carbon atoms) of these groups (however, no ester bonds are bonded to the carbon atoms to which R1, R2, and R3 are bonded in formula (1) above). R ４ and R ５ Each of these is independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group, or a monovalent fluorinated hydrocarbon group. ４ and R ５ If multiple R ４ and R ５ They are either the same or different. R ６ , R ７ and R ８ are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group. I understand １ This is an integer between 0 and 8. Z ＋ (This is a monovalent, radiation-sensitive onium cation.) 【Chemistry 2】 (In formula (2), R ９ This is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R １０ (This is a monovalent group comprising at least one structure selected from the group consisting of lactone structures, cyclic carbonate structures, and sultone structures.)

2. In the above formula (1), R ６ , R ７ and R ８ The radiation-sensitive resin composition according to claim 1, wherein all atoms are fluorine atoms.

3. In the above formula (1), m １ The radiation-sensitive resin composition according to claim 1 or 2, wherein is an integer from 1 to 4.

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

5. The radiation-sensitive resin composition according to claim 1 or 2, wherein the content of the onium salt compound is 0.1 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the resin.

6. In the above formula (2), R １０ The radiation-sensitive resin composition according to claim 1 or 2, wherein is a polycyclic lactone structure, a polycyclic carbonate structure, or a polycyclic sultone structure.

7. In the above formula (2), R １０ The radiation-sensitive resin composition according to claim 6, wherein the polycyclic lactone structure in is a norbornane lactone structure or an adamantane lactone structure.

8. The radiation-sensitive resin composition according to claim 1 or 2, wherein the content of the structural unit (I) in the total structural units constituting the resin is 1 mol% or more and 80 mol% or less.

9. The radiation-sensitive resin composition according to claim 1 or 2, wherein the resin further comprises a structural unit (II) having an acid-dissociable group.

10. The above structural unit (II) is represented by the following formula (3), the radiation-sensitive resin composition according to claim 9. 【Transformation 3】 (In formula (3), R １７ These are a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R １８ It is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R １９ and R ２０ Each of these is independently either a monovalent linear hydrocarbon group having 1 to 10 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or R １９ and R ２０ (This represents a divalent alicyclic group with 3 to 20 carbon atoms, which can be combined with other carbon atoms to form a bonded structure.)

11. A radiation-sensitive resin composition according to claim 1 or 2, further comprising an acid diffusion control agent.

12. A step of forming a resist film by directly or indirectly applying the radiation-sensitive resin composition according to claim 1 or 2 to a substrate, The process of exposing the above-mentioned resist film, The process involves developing the exposed resist film with a developer solution. A pattern formation method, including the following.

13. The pattern formation method according to claim 12, wherein the exposure is performed using an ArF excimer laser or extreme ultraviolet light.