Radiation-sensitive composition, pattern formation method, polymer, and compound

Abstract

Provided are: a radiation-sensitive composition which has excellent CDU and excellent post-develop defect suppressing properties; a pattern formation method; a polymer; and a compound. This radiation-sensitive composition comprises: a polymer that includes at least one structural unit selected from the group consisting of a structural unit (IA) represented by formula (1A) and a structural unit (IB) represented by formula (1B); and a solvent.

Description

Radiation-sensitive composition, pattern forming method, polymer and compound

[0001] The present invention relates to a radiation-sensitive composition, a pattern forming method, a polymer, and a compound.

[0002] Photolithography techniques using resist compositions are used to form fine circuits in semiconductor elements. A typical procedure involves, for example, exposing a coating of the resist composition to radiation through a mask pattern to generate an acid, which is then catalyzed by a reaction that causes a difference in the solubility of the polymer in an alkaline or organic solvent-based developer between the exposed and unexposed areas, thereby forming a resist pattern on a substrate.

[0003] The photolithography technology described above uses short-wavelength radiation such as ArF excimer lasers, or combines this radiation with liquid immersion lithography to promote pattern miniaturization. As a next-generation technology, efforts are being made to utilize even shorter-wavelength radiation such as electron beams, X-rays, and EUV (extreme ultraviolet).

[0004] As patterns become finer, development of polymers, which are components of resist materials, is also progressing (JP 2023-161653 A).

[0005] JP 2023-161653 A

[0006] In developing the above-mentioned next-generation technology, resist performances equivalent to or better than conventional ones are required in terms of sensitivity, CDU, and suppression of development defects.

[0007] An object of the present invention is to provide a radiation-sensitive composition, a pattern-forming method, a polymer, and a compound that are excellent in sensitivity, CDU, and suppression of development defects during pattern formation.

[0008] As a result of extensive research into solving the above problem, the present inventors have found that the above object can be achieved by employing the following configuration, and have thus completed the present invention.

[0009] In one embodiment, the present invention relates to a radiation-sensitive composition comprising: a polymer including at least one structural unit selected from the group consisting of a structural unit (IA) represented by the following formula (1A) and a structural unit (IB) represented by the following formula (1B) (hereinafter, both of these may be collectively referred to as "structural unit (I)"); and a solvent. (In formulas (1A) and (1B), R α is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ａ is a single bond or a divalent linking group. Ar is a (p+q+r+s+1)-valent aromatic ring having 3 to 20 carbon atoms. R １ is an acid-dissociable group or —SO ３ - Z ＋ R is a monovalent organic group having 1 to 20 carbon atoms and containing ２ is a hydrogen atom or a monovalent organic group having 6 to 20 carbon atoms and a phenolic hydroxyl group. ３ is a fluoro group, a chloro group, a bromo group, a nitro group, a sulfanyl group, an amino group, a cyano group, a carboxy group, or a monovalent organic group having 1 to 20 carbon atoms. p is an integer of 1 to 3. q and r are each independently 1 or 2. s is an integer of 0 to 3. R １ , R ２ and R ３ When there are multiple R １ , R ２ and R ３ are the same or different. ＋ is a monovalent onium cation. １ is an acid-dissociable group, the carbon atom in Ar to which the iodo group is bonded and —OR ２ The carbon atoms in Ar to which the groups are attached are directly bonded to each other.

[0010] This radiation-sensitive composition can exhibit excellent sensitivity, CDU, and development defect suppression during resist pattern formation. The reason for this is unclear, but is presumed to be as follows: The iodine group in the structural unit (I) of the polymer has a high absorption of radiation such as EUV having a wavelength of 13.5 nm, which increases the secondary electron generation efficiency and increases the sensitivity of the resulting resist film. On the other hand, although the introduction of the iodine group increases hydrophobicity, the introduction of an -OR group on the aromatic ring to which the iodine group is bonded is in close proximity to the iodine group. ２ group, -COOR １ Group, -COO - Z ＋ By introducing a polar structure such as an acid-dissociable group, the polymer as a whole can exhibit good solubility. In addition, when the structural unit (IA) has an acid-dissociable group, the dissolution contrast between the exposed and unexposed areas can be improved, and when the structural unit (IA) has an onium salt structure (-SO ３ - Z ＋ ) or the polymer has an onium salt structure (—COO - Z ＋ In the case where the compound contains the structural unit (IB) having the structure (IB), the diffusion length of the generated acid can be appropriately controlled. It is presumed that the resist performance can be exhibited by the combined action of these factors.

[0011] In one embodiment, the present invention relates to a pattern forming method, comprising: a step of applying the radiation-sensitive composition directly or indirectly to a substrate to form a resist film; a step of exposing the resist film; and a step of developing the exposed resist film with a developer.

[0012] This pattern formation method uses the above-mentioned radiation-sensitive composition, which is capable of exhibiting excellent sensitivity, CDU, and suppression of development defects when forming a resist pattern, and therefore can efficiently form a high-quality resist pattern.

[0013] In one embodiment, the present invention relates to a polymer comprising at least one structural unit selected from the group consisting of a structural unit (IA) represented by the following formula (1A) and a structural unit (IB) represented by the following formula (1B): (In formulas (1A) and (1B), R α is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ａ is a single bond or a divalent linking group. Ar is a (p+q+r+s+1)-valent aromatic ring having 3 to 20 carbon atoms. R １ is an acid-dissociable group or —SO ３ - Z ＋ R is a monovalent organic group having 1 to 20 carbon atoms and containing ２ is a hydrogen atom or a monovalent organic group having 6 to 20 carbon atoms and a phenolic hydroxyl group. ３ is a fluoro group, a chloro group, a bromo group, a nitro group, a sulfanyl group, an amino group, a cyano group, a carboxy group, or a monovalent organic group having 1 to 20 carbon atoms. p is an integer of 1 to 3. q and r are each independently 1 or 2. s is an integer of 0 to 3. R １ , R ２ and R ３ When there are multiple R １ , R ２ and R ３ are the same or different. ＋ is a monovalent onium cation. １ is an acid-dissociable group, the carbon atom in Ar to which the iodo group is bonded and —OR ２ The carbon atoms in Ar to which the groups are attached are directly bonded to each other.

[0014] The polymer can exhibit good acid generation efficiency, dissolution contrast and solubility due to the introduction of the structural unit (I), and is therefore suitable as a polymer for a radiation-sensitive composition.

[0015] In one embodiment, the present invention relates to a compound represented by the following formula (1a) or (1b): (In formulas (1a) and (1b), R α is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ａ is a single bond or a divalent linking group. Ar is a (p+q+r+s+1)-valent aromatic ring having 3 to 20 carbon atoms. R １is an acid-dissociable group or —SO ３ - Z ＋ R is a monovalent organic group having 1 to 20 carbon atoms and containing ２ is a hydrogen atom or a monovalent organic group having 6 to 20 carbon atoms and a phenolic hydroxyl group. ３ is a fluoro group, a chloro group, a bromo group, a nitro group, a sulfanyl group, an amino group, a cyano group, a carboxy group, or a monovalent organic group having 1 to 20 carbon atoms. p is an integer of 1 to 3. q and r are each independently 1 or 2. s is an integer of 0 to 3. R １ , R ２ and R ３ When there are multiple R １ , R ２ and R ３ are the same or different. ＋ is a monovalent onium cation. １ is an acid-dissociable group, the carbon atom in Ar to which the iodo group is bonded and —OR ２ The carbon atoms in Ar to which the groups are attached are directly bonded to each other.

[0016] When the compound is introduced as a structural unit into a polymer, it can impart good acid generation efficiency, dissolution contrast, and solubility to the polymer, and is therefore suitable as a compound that provides the structural unit (I) of the polymer in the radiation-sensitive composition.

[0017] In this specification, "organic group" refers to a group having at least one carbon atom. However, this does not include groups that by themselves represent functional groups or characteristic groups (e.g., cyano, carboxy, carbonyl, formyl, carbamoyl, etc.). "Fused ring" refers to a polycyclic structure formed by adjacent rings sharing one edge (the bond between two adjacent atoms). "Assembly ring" refers to a structure in which two adjacent rings are bonded by a single bond. When attached to the structure of a substituent, "n-" represents a linear structure, "s-" represents a secondary carbon structure, and "t-" represents a tertiary carbon structure.

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

[0019] Radiation-Sensitive Composition The radiation-sensitive composition according to this embodiment (hereinafter also simply referred to as the "composition") contains a polymer (hereinafter also referred to as the "base polymer") and a solvent. The composition may contain a radiation-sensitive acid generator and an acid diffusion controller. Other optional components may also be included as long as they do not impair the effects of the present invention.

[0020] <Polymer> The polymer (i.e., base polymer) is an aggregate of polymer chains containing the structural unit (I). In addition to the structural unit (I), the base polymer may also contain a structural unit having a phenolic hydroxyl group (hereinafter also referred to as "structural unit (II)") or a structural unit containing a lactone structure (hereinafter also referred to as "structural unit (III)").

[0021] (Structural Unit (I)) The structural unit (I) is at least one structural unit selected from the group consisting of the structural unit (IA) and the structural unit (IB). The base polymer may contain, as the structural unit (I), one or more structural units (IA), one or more structural units (IB), or one or more structural units (IA) and one or more structural units (IB).

[0022] (Structural Unit (IA)) The structural unit (IA) is a structural unit represented by the following formula (1A). (In formula (1A), R α is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ａ is a single bond or a divalent linking group. Ar is a (p+q+r+s+1)-valent aromatic ring having 3 to 20 carbon atoms. R １ is an acid-dissociable group or —SO ３ - Z ＋ R is a monovalent organic group having 1 to 20 carbon atoms and containing ２ is a hydrogen atom or a monovalent organic group having 6 to 20 carbon atoms and a phenolic hydroxyl group.３ is a fluoro group, a chloro group, a bromo group, a nitro group, a sulfanyl group, an amino group, a cyano group, a carboxy group, or a monovalent organic group having 1 to 20 carbon atoms. p is an integer of 1 to 3. q and r are each independently 1 or 2. s is an integer of 0 to 3. R １ , R ２ and R ３ When there are multiple R １ , R ２ and R ３ are the same or different. ＋ is a monovalent onium cation. １ is an acid-dissociable group, the carbon atom in Ar to which the iodo group is bonded and —OR ２ The carbon atoms in Ar to which the groups are attached are directly bonded to each other.

[0023] First, R in the above formula (1A) １ is an acid-dissociable group (hereinafter, this embodiment will also be referred to as "structural unit (IA-1)"), and then R １ Ga-SO ３ - Z ＋ An embodiment in which the structural unit (IA-1) is a monovalent organic group having 1 to 20 carbon atoms and containing the following formula (hereinafter, this embodiment may be referred to as "structural unit (IA-2)") will be described.

[0024] (Structural Unit (IA-1)) The structural unit (IA-1) is a unit represented by the formula (1A) above, where R １ is an acid-dissociable group.

[0025] L Ａ Examples of the divalent linking group represented by the formula (I) include a divalent hydrocarbon group such as an alkanediyl group, a cycloalkanediyl group, an alkenediyl group, or an arenediyl group, a group in which some or all of the hydrogen atoms of the divalent hydrocarbon group have been substituted with substituents, a divalent heteroatom-containing group, a group in which the divalent heteroatom-containing group is incorporated between the carbon-carbon bonds of the divalent hydrocarbon group, or a group comprising a combination of these.

[0026] The alkanediyl group is preferably an alkanediyl group having 1 to 8 carbon atoms, such as a methanediyl group, an ethanediyl group, a 1,3-propanediyl group, or a 2,2-propanediyl group.

[0027] Examples of the cycloalkanediyl group include monocyclic cycloalkanediyl groups such as cyclopentanediyl and cyclohexanediyl groups, and polycyclic cycloalkanediyl groups such as norbornanediyl and adamantanediyl groups. The cycloalkanediyl group is preferably a cycloalkanediyl group having 5 to 12 carbon atoms.

[0028] Examples of the alkenediyl group include an ethenediyl group, a propenediyl group, a butenediyl group, etc. The alkenediyl group is preferably an alkenediyl group having 2 to 6 carbon atoms.

[0029] Examples of the arenediyl group include a phenylene group, a tolylene group, a naphthylene group, etc. The arenediyl group is preferably an arenediyl group having 6 to 15 carbon atoms.

[0030] Examples of the divalent heteroatom-containing group include -CO-, -CS-, -O-, -S-, and -SO ２ -, -NR'-, or a combination of two or more of these groups, where R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

[0031] L Ａ Examples of the substituent that can substitute some or all of the hydrogen atoms in include a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom; a hydroxy group; a carboxy group; a cyano group; a nitro group; an alkyl group; an alkoxy group; an alkoxycarbonyl group; an alkoxycarbonyloxy group; an acyl group; a group in which the hydrogen atoms of these groups are substituted with halogen atoms; a group that is a combination of these groups; or an oxo group (═O).

[0032] L ＡExamples of the alkyl group as a substituent include linear or branched alkyl groups having 1 to 8 carbon atoms, such as methyl, ethyl, and propyl. Examples of the alkoxy group include linear or branched alkoxy groups having 1 to 8 carbon atoms, such as methoxy, ethoxy, and propoxy. Examples of the alkoxycarbonyl group include alkoxycarbonyl groups having 1 to 6 carbon atoms, such as methoxycarbonyl and ethoxycarbonyl. Examples of the alkoxycarbonyloxy group include linear or alicyclic alkoxycarbonyloxy groups having 2 to 16 carbon atoms, such as methoxycarbonyloxy, butoxycarbonyloxy, and adamantylmethyloxycarbonyloxy. Examples of the acyl group include aliphatic or aromatic acyl groups having 2 to 12 carbon atoms, such as acetyl, propionyl, benzoyl, and acryloyl. Examples of the acyloxy group include aliphatic or aromatic acyloxy groups having 2 to 12 carbon atoms, such as an acetyloxy group, a propionyloxy group, a benzoyloxy group, and an acryloyloxy group.

[0033] L Ａ is a single bond or -COO- ＊ (* indicates a bond on the Ar side), and a single bond is more preferred.

[0034] The aromatic ring in Ar is not particularly limited as long as it has an aromatic ring structure. Examples of the aromatic ring include aromatic hydrocarbon rings having 6 to 20 carbon atoms, such as a benzene ring, a naphthalene ring, an anthracene ring, a phenalene ring, a phenanthrene ring, a pyrene ring, a fluorene ring, and a perylene ring; aromatic heterocycles having 3 to 20 carbon atoms, such as an imidazole ring, a furan ring, a pyrrole ring, a thiophene ring, a phosphole ring, a pyrazole ring, an oxazole ring, an isoxazole ring, a thiazole ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a pyridazine ring, a triazine ring, an indole ring, a benzimidazole ring, a benzofuran ring, and a quinoline ring; and combinations thereof. The combination of these rings may be a fused ring, a ring assembly (a structure in which two rings are bonded by a single bond), or a spiro structure. Among these, a benzene ring and a naphthalene ring are preferred as the aromatic ring, and a benzene ring is more preferred.

[0035] Examples of the (p+q+r+s+1)-valent aromatic ring having 3 to 20 carbon atoms represented by Ar include groups in which (p+q+r+s+1) hydrogen atoms have been removed from the above-mentioned aromatic ring.

[0036] R １ The acid-dissociable group represented by the formula (I) is not particularly limited, and examples thereof include R １ a structure forming a tertiary alkyl ester moiety together with —COO— to which R is bonded; １ a structure that forms, together with —COO— to which R is bonded, a secondary unsaturated alkyl ester moiety having a double bond between the β-position carbon and the γ-position carbon of the terminal oxygen atom of —COO—; １ In order to improve the pattern formability of the radiation-sensitive composition, the acid-dissociable group is preferably represented by the following formula (i):

[0037]

[0038] In the above formula (i), R ８ R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ９ and R １０ are each independently a hydrogen atom, a substituted or unsubstituted monovalent chain hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a substituted or unsubstituted divalent alicyclic group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded. ９ and R １０ There is no case where both of R are hydrogen atoms. ９ or R １０ When one of R is a hydrogen atom, ８ is a substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms. * is a bond to an oxygen atom.

[0039] The above R ８ Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by the formula (I) include a chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0040] Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an s-butyl group, an isobutyl group, and a t-butyl group; alkenyl groups such as an ethenyl group, a propenyl group, and a butenyl group; and alkynyl groups such as an ethynyl group, a propynyl group, and a butynyl group.

[0041] Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include monocyclic alicyclic saturated hydrocarbon groups such as a cyclopentyl group and a cyclohexyl group; polycyclic alicyclic saturated hydrocarbon groups such as a norbornyl group, an adamantyl group, a tricyclodecyl group and a tetracyclododecyl group; monocyclic alicyclic unsaturated hydrocarbon groups such as a cyclopentenyl group and a cyclohexenyl group; and polycyclic alicyclic unsaturated hydrocarbon groups such as a norbornenyl group, a tricyclodecenyl group and a tetracyclododecenyl group.

[0042] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xylyl, naphthyl, and anthryl groups, and aralkyl groups such as benzyl, phenethyl, naphthylmethyl, and anthrylmethyl groups.

[0043] R ９ and R １０ As the divalent alicyclic group having 3 to 20 carbon atoms constituted by combining these together with the carbon atoms to which they are bonded, a group in which one hydrogen atom has been removed from the above-mentioned monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms can be suitably used.

[0044] Among these, R ８ ~R １０ are each an alkyl group having 1 to 4 carbon atoms, or R ８ is an alkyl group, alkenyl group or phenyl group having 1 to 4 carbon atoms, and R ９ and R １０ It is preferable that the alicyclic structure constituted by the formula: is a polycyclic or monocyclic cycloalkane structure.

[0045] R ８ ~R １０ When has a substituent, the substituent is L in the above formula (1A). ＡThe substituents that may be possessed by the group may be employed.

[0046] Preferred examples of the acid-dissociable group include structures represented by the following formulae (i-1) to (i-8).

[0047]

[0048] In the above formulas (i-1) to (i-8), R ８ ~R １０ has the same meaning as in formula (i) above. Ｌ１１ are each independently a halogen atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an alkyl group, a fluorinated alkyl group, an alkoxycarbonyloxy group, an acyl group, an acyloxy group, or an alkoxy group. i and j are each independently an integer of 1 to 4. g, k, and l are each 0 or 1. 3a are each independently an integer of 0 to 3. When 3a is 2 or more, multiple R Ｌ１１ are the same or different. * is a bond to the oxygen atom.

[0049] i and j are preferably 1. ８ R is preferably a methyl group, an ethyl group, an isopropyl group, a t-butyl group, a vinyl group, a phenyl group, or an iodophenyl group. ９ and R １０ As the alkyl group, a methyl group or an ethyl group is preferred.

[0050] When the acid-dissociable group contains a ring structure, some of the carbon atoms constituting the ring structure may be substituted with a divalent heteroatom-containing group, such as -CO-, -CS-, -NR'-, -O-, -S-, or -SO ２ - or a divalent group formed by combining these groups, etc. R' is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms.

[0051] In addition to or instead of the acid-dissociable group represented by formula (i), the acid-dissociable group may contain structures represented by the following formulae (1g) to (3g).

[0052]

[0053] In the above formulas (1g) to (3g), Rβｆ are each independently a hydrogen atom or a chain alkyl group having 1 to 5 carbon atoms. １ is an integer of 1 to 4. * is a bond to the oxygen atom.

[0054] The above R βｆ is preferably a hydrogen atom, a methyl group, or an ethyl group. １ As the number, 1 or 2 is preferred.

[0055] R ２ Examples of the monovalent organic group having 6 to 20 carbon atoms and a phenolic hydroxyl group represented by the formula (I) include a group in which one or more hydroxy groups are bonded to an aromatic hydrocarbon group having 6 to 20 carbon atoms, or a group having 6 to 20 carbon atoms formed by combining such a group with a monovalent organic group having 1 to 20 carbon atoms.

[0056] The aromatic hydrocarbon group having 6 to 20 carbon atoms is R ８ A monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms in the above formula can be suitably used.

[0057] Examples of the monovalent organic group having 1 to 20 carbon atoms include a monovalent hydrocarbon group having 1 to 20 carbon atoms, a group having a divalent heteroatom-containing group between carbon atoms of the hydrocarbon group (between two adjacent or non-adjacent carbon atoms) or at the end of the hydrocarbon group (hereinafter also referred to as "group (α)"), a group in which some or all of the hydrogen atoms in the hydrocarbon group or the group (α) have been substituted with a monovalent heteroatom-containing group, and a group comprising a combination thereof.

[0058] The monovalent hydrocarbon group having 1 to 20 carbon atoms includes R ８ A monovalent hydrocarbon group having 1 to 20 carbon atoms and represented by the following formula can be suitably used.

[0059] Examples of heteroatoms constituting the divalent or monovalent heteroatom-containing group include oxygen atoms, nitrogen atoms, sulfur atoms, phosphorus atoms, silicon atoms, halogen atoms, etc. Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.

[0060] As the divalent hetero atom-containing group, the divalent hetero atom-containing groups shown above in relation to the acid-dissociable group can be suitably employed.

[0061] Examples of the monovalent heteroatom-containing group include a hydroxy group, a carboxy group, a sulfanyl group, a cyano group, a nitro group, and a halogen atom.

[0062] R ２ is preferably a hydrogen atom.

[0063] R ３ As the monovalent organic group having 1 to 20 carbon atoms represented by R ２ The monovalent organic groups having 1 to 20 carbon atoms shown in the above formula can be suitably used.

[0064] Preferably, p is 1 or 2.

[0065] Preferably, q and r are 1.

[0066] s is preferably an integer of 0 to 2, and more preferably 0 or 1.

[0067] R in the above formula (1A) １ The structural unit (IA-1) in which is an acid-dissociable group is preferably represented by the following formula (1A-1).

[0068] (In formula (1A-1), R α , R ２ , R ３ and p have the same meanings as in formula (1A). ａ is a single bond or -COO- ＊ * indicates a bond on the benzene ring side. R ８ ~R １０ has the same meaning as in formula (i) above. s1 is an integer of 0 to 2.

[0069] L ａ is preferably a single bond.

[0070] s1 is preferably 0 or 1.

[0071] Specific examples of the monomer compound that provides the structural unit (IA-1) (including the case of formula (1A-1)) are not particularly limited, and include structures represented by the following formulae (1A-1-1) to (1A-1-24).

[0072]

[0073]

[0074] When the polymer contains the structural unit (IA-1), the lower limit of the content of the structural unit (IA-1) in the total structural units constituting the polymer is preferably 10 mol%, more preferably 15 mol%, and even more preferably 18 mol%.The upper limit of the content may be 100 mol%, but is preferably 60 mol%, and more preferably 40 mol%.

[0075] (Synthesis of Monomer Compound Providing Structural Unit (1A-1)) The monomer compound providing the structural unit (1A-1) can be synthesized by a known method. A representative synthesis scheme is shown for the case where p, q, r, and s correspond to the structure of the above formula (1A) where all of them are 1.

[0076]

[0077] The ketone (aa-1-1) is converted to an alkene (aa-1) by Wittig reaction, and then the desired acid-labile group structure R １ By carrying out an esterification reaction with an alcohol having the formula (Ia-1), a monomer compound (Ia-1) can be produced, which gives the structural unit (Ia-1). Other structures can also be synthesized by appropriately changing the structure of the ketone body or alcohol.

[0078] (Structural Unit (IA-2)) The structural unit (IA-2) is a unit represented by the formula (1A) above, where R １ Ga-SO ３ - Z ＋ The structural unit (IA-1) has a structure that is a monovalent organic group having 1 to 20 carbon atoms and containing the following structural unit (IA-2):

[0079] R １ -SO represented by ３- Z ＋ The monovalent organic group having 1 to 20 carbon atoms containing -SO is a monovalent organic group having 1 to 20 carbon atoms containing -SO ３ - Z ＋ It is sufficient that -SO is bonded. ３ - Z ＋ The number of -SO is not particularly limited, and may be one or two or more. ３ - Z ＋ The onium salt structure represented by the following formula preferably functions as a radiation-sensitive acid-generating structure: The radiation-sensitive acid-generating structure is a structure that generates an acid that dissociates the acid-dissociable group upon exposure to light.

[0080] The monovalent organic group having 1 to 20 carbon atoms includes R ２ The monovalent organic groups having 1 to 20 carbon atoms shown in the following formula can be suitably used.

[0081] R １ -SO ３ It is preferable that the organic group has a structure in which an electron-withdrawing group is bonded to a carbon atom at the α-position or β-position relative to the sulfur atom of the organic group.

[0082] Examples of the electron-withdrawing group include a fluorine atom, a fluorinated hydrocarbon group, a nitro group, a cyano group, etc. As the fluorinated hydrocarbon group, a perfluoroalkyl group having 1 to 5 carbon atoms is preferred.

[0083] R １ -SO represented by ３ - Z ＋ The monovalent organic group having 1 to 20 carbon atoms containing the fluorinated alkanediyl group having 1 to 10 carbon atoms includes a group having -SO ３ - Z ＋ As the substituent of the alkyl group, a group to which L in the above formula (1A) is bonded is preferred. Ａ The substituents that may be possessed by the group may be employed.

[0084] Z in the above formula (1A) ＋Examples of the radiolytic onium cation include a radiolytic onium cation. Examples of the radiolytic onium cation include a sulfonium cation, a tetrahydrothiophenium cation, an iodonium cation, etc. Among these, a sulfonium cation or an iodonium cation is preferred, and a sulfonium cation is more preferred.

[0085] The sulfonium cation is preferably represented by the following formula (Q-1):

[0086]

[0087] In the above formula (Q-1), Ra1 and Ra2 each independently represent a substituent. n1 represents an integer of 0 to 5, and when n1 is 2 or greater, multiple Ra1s may be the same or different. n2 represents an integer of 0 to 5, and when n2 is 2 or greater, multiple Ra2s may be the same or different. n3 represents an integer of 0 to 5, and when n3 is 2 or greater, multiple Ra3s may be the same or different. Ra3 represents a substituent. Ra1 and Ra2 may be bonded to each other to form a ring. When n1 is 2 or greater, multiple Ra1s may be bonded to each other to form a ring. When n2 is 2 or greater, multiple Ra2s may be bonded to each other to form a ring.

[0088] The substituents represented by Ra1, Ra2 and Ra3 are preferably an alkyl group, a cycloalkyl group, an alkoxy group, a cycloalkyloxy group, an alkoxycarbonyl group, an alkylsulfonyl group, a hydroxyl group, a halogen atom or a halogenated hydrocarbon group.

[0089] The alkyl groups of Ra1 and Ra2 may be linear or branched. The alkyl groups preferably have 1 to 10 carbon atoms, and examples thereof include methyl, ethyl, n-propyl, i-propyl, n-butyl, 2-methylpropyl, 1-methylpropyl, t-butyl, n-pentyl, neopentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, and n-decyl. Of these, methyl, ethyl, n-butyl, and t-butyl are particularly preferred.

[0090] The cycloalkyl group of Ra1 and Ra2 includes a monocyclic or polycyclic cycloalkyl group (preferably a cycloalkyl group having 3 to 20 carbon atoms), such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclododecanyl, cyclopentenyl, cyclohexenyl, and cyclooctadienyl groups. Of these, cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups are particularly preferred.

[0091] Examples of the alkyl group moiety of the alkoxy group of Ra1 and Ra2 include those previously listed as the alkyl groups of Ra1 and Ra2. As the alkoxy group, a methoxy group, an ethoxy group, an n-propoxy group, and an n-butoxy group are particularly preferred.

[0092] Examples of the cycloalkyl group moiety of the cycloalkyloxy group of Ra1 and Ra2 include those previously listed as the cycloalkyl groups of Ra1 and Ra2. As this cycloalkyloxy group, a cyclopentyloxy group and a cyclohexyloxy group are particularly preferred.

[0093] Examples of the alkoxy group moiety of the alkoxycarbonyl group of Ra1 and Ra2 include those previously listed as the alkoxy group of Ra1 and Ra2. As the alkoxycarbonyl group, a methoxycarbonyl group, an ethoxycarbonyl group, and an n-butoxycarbonyl group are particularly preferred.

[0094] Examples of the alkyl group moiety of the alkylsulfonyl group of Ra1 and Ra2 include those previously listed as the alkyl groups of Ra1 and Ra2. Also, examples of the cycloalkyl group moiety of the cycloalkylsulfonyl group of Ra1 and Ra2 include those previously listed as the cycloalkyl groups of Ra1 and Ra2. Particularly preferred alkylsulfonyl groups or cycloalkylsulfonyl groups are methanesulfonyl, ethanesulfonyl, n-propanesulfonyl, n-butanesulfonyl, cyclopentanesulfonyl, and cyclohexanesulfonyl.

[0095] Each of the groups Ra1 and Ra2 may further have a substituent, such as a halogen atom such as a fluorine atom (preferably a fluorine atom), a hydroxy group, a carboxy group, a cyano group, a nitro group, an alkoxy group, a cycloalkyloxy group, an alkoxyalkyl group, a cycloalkyloxyalkyl group, an alkoxycarbonyl group, a cycloalkyloxycarbonyl group, an alkoxycarbonyloxy group, and a cycloalkyloxycarbonyloxy group.

[0096] Examples of the halogen atom for Ra1 and Ra2 include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, with a fluorine atom and an iodine atom being preferred.

[0097] The halogenated hydrocarbon group of Ra1 and Ra2 is preferably a halogenated alkyl group. Examples of the alkyl group and halogen atom constituting the halogenated alkyl group are the same as those described above. Among them, a fluorinated alkyl group is preferred, and CF ３ is more preferred.

[0098] As described above, Ra1 and Ra2 may be bonded to each other to form a ring (i.e., a heterocycle containing a sulfur atom). In this case, it is preferable that Ra1 and Ra2 are bonded to each other to form a single bond or a divalent linking group. Examples of the divalent linking group include -COO-, -OCO-, -CO-, -O-, -S-, -SO-, and -SO ２ -, an alkylene group, a cycloalkylene group, an alkenylene group, or a combination of two or more thereof, and preferably has a total carbon number of 20 or less. When Ra1 and Ra2 are bonded to each other to form a ring, Ra1 and Ra2 are bonded to each other to form -COO-, -OCO-, -CO-, -O-, -S-, -SO-, -SO ２It is preferable to form - or a single bond. Among these, it is more preferable to form -O-, -S- or a single bond, and it is particularly preferable to form a single bond. Furthermore, when n1 is 2 or more, multiple Ra1s may be linked to each other to form a ring, and when n2 is 2 or more, multiple Ra2s may be linked to each other to form a ring. Such an example includes, for example, an embodiment in which two Ra1s are linked to each other to form a naphthalene ring together with the benzene ring to which they are bonded.

[0099] Ra3 is preferably a fluorine atom, an iodine atom, or a group having one or more fluorine atoms. Examples of the group having a fluorine atom include groups in which the alkyl group, cycloalkyl group, alkoxy group, cycloalkyloxy group, alkoxycarbonyl group, and alkylsulfonyl group represented by Ra1 and Ra2 are substituted with a fluorine atom. Among these, fluorinated alkyl groups are preferred, and CF ３ , C ２ F ５ , C ３ F ７ , C ４ F ９ , C ５ F １１ , C ６ F １３ , C ７ F １５ , C ８ F １７ , C.H. ２ CF ３ , C.H. ２ CH ２ CF ３ , C.H. ２ C ２ F ５ , C.H. ２ CH ２ C ２ F ５ , C.H. ２ C ３ F ７ , C.H. ２ CH ２ C ３ F ７ , C.H. ２ C ４ F ９ and CH ２ CH ２ C ４F ９ More preferred examples include CF ３ can be particularly preferably mentioned.

[0100] Ra3 is a fluorine atom or CF ３ is preferably, and a fluorine atom is more preferably.

[0101] n1 and n2 each independently represent an integer of 0 to 3, preferably an integer of 0 to 2.

[0102] n3 is preferably an integer of 1 to 3, and more preferably 1 or 2.

[0103] (n1+n2+n3) is preferably an integer of 1 to 15, more preferably an integer of 1 to 9, still more preferably an integer of 2 to 6, and particularly preferably an integer of 3 to 6. When (n1+n2+n3) is 1, n3=1 and Ra3 is a fluorine atom, an iodine atom, or CF ３ When (n1 + n2 + n3) is 2, n1 = n3 = 1, and Ra1 and Ra3 are each independently a fluorine atom, an iodine atom, or CF ３ and n3=2 and Ra3 is a fluorine atom, an iodine atom, or CF ３ When (n1+n2+n3) is 3, n1=n2=n3=1 and Ra1 to Ra3 are each independently a fluorine atom, an iodine atom, or CF ３ When (n1 + n2 + n3) is 4, n1 = n3 = 2 and Ra1 and Ra3 are each independently a fluorine atom, an iodine atom, or CF ３ When (n1+n2+n3) is 5, n1=n2=1 and n3=3, and Ra1 to Ra3 are each independently a fluorine atom, an iodine atom, or CF ３ a combination in which n1=n2=2 and n3=1, and Ra1 to Ra3 are each independently a fluorine atom, an iodine atom, or CF ３ and n3=5 and each Ra3 is independently a fluorine atom, an iodine atom, or CF ３When (n1+n2+n3) is 6, n1=n2=n3=2 and Ra1 to Ra3 are each independently a fluorine atom, an iodine atom, or CF ３ A combination in which:

[0104] Specific examples of such sulfonium cations represented by the above formula (Q-1) include the following: The fluorine atom and iodine atom in the following sulfonium cations can be substituted with hydrogen atoms or R １７ It may be substituted with the substituents shown in the above.

[0105]

[0106]

[0107]

[0108]

[0109] The iodonium cation is preferably a diaryliodonium cation. The aryl group is preferably a phenyl group. The diaryliodonium cation preferably has one or more fluorine atoms, iodine atoms, or fluorinated hydrocarbon groups as substituents on the aryl group.

[0110] The structural unit (IA-2) is preferably represented by the following formula (1A-2).

[0111] (In formula (1A-2), R α , L ａ , R ２ , R ３ , p and s1 have the same meanings as in formula (1A-1) above. ｂ -SO ３ - Z is a divalent linking group having 2 to 20 carbon atoms in which an electron-withdrawing group is bonded to the carbon atom at the α- or β-position relative to the sulfur atom in １ ＋ is a sulfonium cation or an iodonium cation.

[0112] R in the above formula (1A) １ -SO represented by ３- Z ＋ is -L in the above formula (1A-2). ｂ -SO ３ - Z １ ＋ Corresponds to.

[0113] L ｂ In the formula (1A), the divalent linking group having 2 to 20 carbon atoms is L Ａ Among the divalent linking groups represented by the following formula, groups having 2 to 20 carbon atoms can be suitably used. ｂ As the —SO 3 group, an alkanediyl group having 2 to 10 carbon atoms is preferred, an alkanediyl group having 2 to 6 carbon atoms is more preferred, and an alkanediyl group having 2 to 4 carbon atoms is even more preferred. ３ - An electron-withdrawing group is bonded to the carbon atom alpha or beta to the sulfur atom in the alkylene.

[0114] The electron-withdrawing group is R １ The electron-withdrawing groups shown in the following formula can be suitably employed.

[0115] Z １ ＋ The sulfonium cation and iodonium cation represented by the formula (1A) are ＋ The sulfonium cations and iodonium cations shown in the following formula can be suitably employed.

[0116] Specific examples of the monomer compound that provides the structural unit (IA-2) (including the case of formula (1A-2)) are not particularly limited, but include structures represented by the following formulae (1A-2-1) to (1A-2-12).

[0117]

[0118]

[0119] When the polymer contains the structural unit (IA-2), the lower limit of the content of the structural unit (IA-2) in the total structural units constituting the polymer is preferably 2 mol%, more preferably 5 mol%, and even more preferably 8 mol%.The upper limit of the content is preferably 20 mol%, more preferably 15 mol%, and even more preferably 12 mol%.

[0120] (Synthesis of Monomer Compound Providing Structural Unit (1A-2)) The monomer compound providing the structural unit (1A-2) can be synthesized by a known method. A representative synthesis scheme is shown below: １ is -L in the above formula (1A-2). ｂ -SO ３ - Z １ ＋ This shows the case where

[0121]

[0122] A condensation reaction between a carboxylic acid (aa-2) and an alcohol having a desired onium salt structure can produce a monomer compound (1a-2) that gives the structural unit (1A-2). Other structures can also be synthesized by appropriately changing the structures of the carboxylic acid and alcohol.

[0123] (Structural Unit (IB)) The structural unit (IB) is a structural unit represented by the following formula (1B).

[0124] (In formula (1B), R α is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ａ is a single bond or a divalent linking group. Ar is a (p+q+r+s+1)-valent aromatic ring having 3 to 20 carbon atoms. R ２ is a hydrogen atom or a monovalent organic group having 6 to 20 carbon atoms and a phenolic hydroxyl group. ３is a fluoro group, a chloro group, a bromo group, a nitro group, a sulfanyl group, an amino group, a cyano group, a carboxy group, or a monovalent organic group having 1 to 20 carbon atoms. p is an integer of 1 to 3. q and r are each independently 1 or 2. s is an integer of 0 to 3. R １ , R ２ and R ３ When there are multiple R １ , R ２ and R ３ are the same or different. ＋ is a monovalent onium cation.

[0125] R α , L Ａ , Ar, R ２ , R ３ , p, q, r, s and Z ＋ As for the above, the configuration and values ​​shown in the above formula (1A) can be adopted.

[0126] The structural unit (IB) is preferably a structural unit represented by the following formula (1B-1):

[0127] (In formula (1B-1), R α , R ２ , R ３ and p have the same meanings as in formula (1A). ａ is a single bond or -COO- ＊ * is a bond on the benzene ring side. s1 is an integer of 0 to 2. Z １ ＋ is a sulfonium cation or an iodonium cation.

[0128] L ａ , s1 and Z １ ＋ As the value, the configuration and values ​​shown in the above formula (1A-2) can be adopted.

[0129] Specific examples of the monomer compound that provides the structural unit (IB) (including the case of formula (1B-1)) are not particularly limited, and include structures represented by the following formulae (1B-1-1) to (1B-1-6).

[0130]

[0131] When the polymer contains the structural unit (IB), the lower limit of the content of the structural unit (IB) in all structural units constituting the polymer is preferably 1 mol%, more preferably 2 mol%, and even more preferably 3 mol%, and the upper limit of the content is preferably 10 mol%, more preferably 8 mol%, and even more preferably 6 mol%.

[0132] (Synthesis of Monomer Compound Providing Structural Unit (1B)) The monomer compound providing the structural unit (1B) can be synthesized by a known method. A representative synthesis scheme is shown for the case where p, q, r, and s correspond to the structure of the above formula (1B) where all of them are 1.

[0133] (In the scheme, X - is a halide ion.)

[0134] Carboxylic acid (bb-1) and the desired onium cation Z ＋ By carrying out an esterification (salt exchange) reaction with an onium salt having the formula (Ib-1), a monomer compound (Ib-1) can be produced, which gives the structural unit (Ib). Other structures can also be synthesized by appropriately changing the structure of the carboxylic acid or the onium salt.

[0135] (Structural Unit (II)) The structural unit (II) is a structural unit having a phenolic hydroxyl group (excluding structures corresponding to the structural unit (I)). When the polymer contains the structural unit (II), the solubility in a developer can be more appropriately adjusted, and as a result, the sensitivity of the radiation-sensitive composition can be further improved. Furthermore, when KrF excimer laser light, EUV, electron beams, or the like is used as the radiation to be irradiated in the exposure step of the resist pattern formation method, the structural unit (II) contributes to improving the etching resistance and the difference in developer solubility (dissolution contrast) between exposed and unexposed areas. In particular, the structural unit (II) is suitably applied to pattern formation using exposure to radiation having a wavelength of 50 nm or less, such as electron beams or EUV. The structural unit (II) is preferably represented by the following formula (2):

[0136] (In the above formula (2), R β is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. ＣＡ is a single bond, -COO- ＊ or -O-. * is a bond on the aromatic ring side. R １０２ R is a halogen atom, a cyano group, a nitro group, an alkyl group, an alkoxycarbonyl group, an acyl group, or an acyloxy group. １０２ If there are multiple R １０２ are the same or different. ３ is an integer from 0 to 2, and m ３ is an integer from 1 to 8, and m ４ are each independently an integer of 0 to 8, provided that 1≦m ３ +m ４ ≦2n ３ Meets +5.)

[0137] The above R β From the viewpoint of copolymerizability of the monomer that gives the structural unit (II), the alkyl group is preferably a hydrogen atom or a methyl group.

[0138] L ＣＡ is a single bond or -COO- ＊ is preferred.

[0139] R １０２ The halogen atom, alkyl group, alkoxycarbonyloxy group, acyl group or acyloxy group in the formula (1) is preferably L Ａ The groups listed as the substituents of R can be suitably used. １０２ The halogen atom in is preferably an iodine atom.

[0140] The above n ３ is more preferably 0 or 1, and even more preferably 0.

[0141] The above m ３ is preferably an integer of 1 to 3, more preferably 1 or 2.

[0142] The above m ４ is preferably an integer of 0 to 3, and more preferably an integer of 0 to 2.

[0143] The structural unit (II) is preferably a structural unit represented by the following formulas (2-1) to (2-21) (hereinafter also referred to as "structural unit (II-1) to structural unit (II-21)").

[0144]

[0145]

[0146] In the above formulas (2-1) to (2-21), R β is the same as the above formula (2).

[0147] When the base polymer contains the structural unit (II), the lower limit of the content of the structural unit (II) (total content when multiple types of structural unit (II) are present) relative to all structural units constituting the polymer is preferably 5 mol%, more preferably 10 mol%, and even more preferably 15 mol%. The upper limit of the content is preferably 90 mol%, more preferably 80 mol%, and even more preferably 75 mol%. By setting the content of the structural unit (II) within the above range, the radiation-sensitive composition can achieve further improvements in sensitivity and development contrast.

[0148] (Structural Unit (III)) The structural unit (III) is a structural unit having an acid-dissociable group (excluding structures corresponding to the structural unit (I)). The acid-dissociable group is R １ From the viewpoint of improving the pattern formability of the radiation-sensitive composition, a structural unit represented by the following formula (3) (hereinafter also referred to as "structural unit (III-1)") is preferred.

[0149] (In formula (3), R γ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. １ is a divalent linking group. １Ａ and R １Ｂare each independently a hydrogen atom, a monovalent chain hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a divalent alicyclic group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded. １Ａ and R １Ｂ There is no case where both of Ar and Ar are hydrogen atoms. １ is a (p+q+1)-valent aromatic ring having 5 to 20 ring members. １０１ is a nitro group, a cyano group, a hydroxy group, an alkoxy group, or an amino group. １０１ If there are multiple R １０１ are the same or different. d1 and d2 are each independently 0 or 1. However, when d1 is 1, d2 is 1. d3 is an integer from 1 to 3. d4 is an integer from 0 to 3. However, d3 + d4 is 5 or less.

[0150] L １ As the divalent linking group represented by the formula (1A), Ａ A divalent linking group represented by the following formula can be preferably used.

[0151] L １ The divalent linking group represented by the formula (I) is preferably an alkanediyl group or an arenediyl group, more preferably an alkanediyl group having 1 to 4 carbon atoms or an arenediyl group having 6 to 10 carbon atoms, and even more preferably a methanediyl group or a benzenediyl group.

[0152] R １Ａ and R １Ｂ The monovalent chain hydrocarbon group having 1 to 10 carbon atoms represented by the formula (i) is R ８ Among the chain hydrocarbon groups having 1 to 20 carbon atoms in the above formula, groups having 1 to 10 carbon atoms can be suitably used.

[0153] R １Ａ and R １Ｂ The monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by the formula (i) is R ８ A monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms in the above formula can be suitably used.

[0154] R１Ａ and R １Ｂ As the divalent alicyclic group having 3 to 20 carbon atoms constituted by combining these together with the carbon atoms to which they are bonded, a group in which one hydrogen atom has been removed from the above-mentioned monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms can be suitably used.

[0155] R １Ａ and R １Ｂ is a monovalent chain hydrocarbon group having 1 to 10 carbon atoms, or R １Ａ and R １Ｂ are combined together together with the carbon atoms to which they are bonded, a divalent alicyclic group having 3 to 20 carbon atoms is preferred, a monovalent linear hydrocarbon group having 1 to 10 carbon atoms or a divalent alicyclic group having 5 to 10 carbon atoms is more preferred, and a methyl group, an ethyl group, a cyclopentanediyl group, or a cyclohexanediyl group is even more preferred.

[0156] Ar １ As the aromatic ring in Ar, the aromatic ring in Ar in the above formula (1A) can be suitably used. １ The aromatic ring in Ar is preferably a benzene ring, a thiophene ring or a furan ring, and more preferably a benzene ring. １ The aromatic ring having 5 to 20 ring members and a valence of (p+q+1) is represented by the above Ar １ A group in which (p+q+1) hydrogen atoms have been removed from the aromatic ring of the formula (I) can be suitably used.

[0157] R １０１ The alkoxy group represented by the formula (1) is Ａ Examples of the alkoxy groups include those shown as the substituents of the above.

[0158] d3 is preferably 1 or 2. d4 is preferably 0 or 1.

[0159] Furthermore, the polymer may contain structural units represented by the following formulae (1f) to (3f) as the structural unit (I).

[0160]

[0161] In the above formulas (1f) to (3f), R αｆR are each independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. βｆ are each independently a hydrogen atom or a chain alkyl group having 1 to 5 carbon atoms. １ is an integer from 1 to 4.

[0162] The above R βｆ is preferably a hydrogen atom, a methyl group, or an ethyl group. １ As the number, 1 or 2 is preferred.

[0163] Specific examples of the structural unit (III) (including the structural unit (III-1)) are not particularly limited, but include structures represented by the following formulae (3-1) to (3-51).

[0164]

[0165]

[0166]

[0167] In the formula, R γ is the same as the above formula (3).

[0168] When the base polymer contains the structural unit (III), the lower limit of the content of the structural unit (III) (the total content when multiple types are contained) relative to all structural units constituting the base polymer is preferably 10 mol%, more preferably 20 mol%, and even more preferably 30 mol%. The upper limit of the content is preferably 80 mol%, more preferably 70 mol%, and even more preferably 60 mol%. By setting the content of the structural unit (III) within the above range, the pattern formability of the radiation-sensitive composition can be further improved. When the acid-dissociable group has an iodine group, the sensitivity can be further improved.

[0169] (Structural Unit (IV)) The structural unit (IV) is a structural unit containing at least one selected from the group consisting of a lactone structure, a cyclic carbonate structure, a sultone structure, and a cyclic sulfone structure. By further including the structural unit (IV), the base polymer can adjust its solubility in a developer, and as a result, the radiation-sensitive composition can improve lithography performance such as resolution. In addition, the adhesion between a resist pattern formed from the base polymer and a substrate can be improved.

[0170] The base polymer may contain one or more types of structural unit (IV).

[0171] When the base polymer contains the structural unit (IV), the lower limit of the content of the structural unit (IV) (total when multiple types are contained) relative to all structural units constituting the base polymer is preferably 5 mol%, more preferably 10 mol%, and even more preferably 15 mol%. The upper limit of the content is preferably 40 mol%, more preferably 30 mol%, and even more preferably 25 mol%. By setting the content of the structural unit (IV) within the above range, the radiation-sensitive composition can further improve lithography performance such as resolution and adhesion of the formed resist pattern to the substrate.

[0172] (Structural Unit (V)) The structural unit (V) is a structural unit containing a polar group (excluding those corresponding to the structural units (I) to (IV)). By further including the structural unit (V), the base polymer can adjust its solubility in a developer, thereby improving the lithography performance, such as resolution, of the radiation-sensitive composition. Examples of the polar group include a hydroxy group, a carboxy group, a cyano group, a nitro group, and a sulfonamide group. Of these, a hydroxy group and a carboxy group are preferred, and a hydroxy group is more preferred.

[0173] Examples of the structural unit (V) include structural units represented by the following formula:

[0174]

[0175]

[0176] In the above formula, R Ｋ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[0177] When the base polymer has the structural unit (V) having the polar group, the lower limit of the content of the structural unit (V) is preferably 1 mol%, more preferably 2 mol%, and even more preferably 3 mol%, based on the total structural units constituting the base polymer. The upper limit of the content is preferably 30 mol%, more preferably 25 mol%, and even more preferably 20 mol%. By setting the content of the structural unit (V) within the above range, the lithography performance such as resolution of the radiation-sensitive composition can be further improved.

[0178] (Method of Synthesizing Base Polymer) The base polymer can be synthesized, for example, by polymerizing monomers that provide each structural unit in an appropriate solvent using a radical polymerization initiator or the like.

[0179] The molecular weight of the base polymer is not particularly limited, but the lower limit of the weight average molecular weight (Mw) in terms of polystyrene measured by gel permeation chromatography (GPC) is preferably 2,000, more preferably 4,000, and even more preferably 5,000. The upper limit of Mw is preferably 20,000, more preferably 13,000, and even more preferably 9,000. By setting the Mw of the base polymer within the above range, the resulting resist film can exhibit good heat resistance and developability.

[0180] The ratio (Mw / Mn) of Mw to the polystyrene-equivalent number average molecular weight (Mn) of the base polymer as determined by GPC is usually 1 or more and 5 or less, preferably 1 or more and 3 or less, and more preferably 1 or more and 2 or less.

[0181] The method for measuring Mw and Mn of the polymer in this specification is as described in the Examples.

[0182] The lower limit of the content of the base polymer is preferably 50% by mass, more preferably 60% by mass, and even more preferably 70% by mass, based on the total solid content of the radiation-sensitive composition, and the upper limit of the content is preferably 98% by mass, more preferably 95% by mass, and even more preferably 92% by mass.

[0183] <Other Polymers> The radiation-sensitive composition of the present embodiment may contain, as another polymer, a polymer having a higher mass content of fluorine atoms than the base polymer (hereinafter also referred to as a "high-fluorine-content polymer"). When the radiation-sensitive composition contains a high-fluorine-content polymer, the high-fluorine-content polymer can be unevenly distributed in the surface layer of the resist film relative to the base polymer, and as a result, the state of the resist film surface and the component distribution in the resist film can be controlled to desired states.

[0184] The high-fluorine-containing polymer may have a structural unit represented by the following formula (6) (hereinafter also referred to as "structural unit (VI)").

[0185] In the above formula (6), R ７３ is a hydrogen atom, a methyl group, or a trifluoromethyl group. Ｌ represents a single bond, an oxygen atom, a sulfur atom, -COO-, or -SO ２ -ONH-, -CONH- or -OCONH-. ７４ 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.

[0186] The high-fluorine content polymer may have a fluorine atom-containing structural unit represented by the following formula (f-2) (hereinafter also referred to as structural unit (VII)) in addition to or instead of the structural unit (VI). By having the structural unit (VII), the high-fluorine content polymer has improved solubility in an alkaline developer, and can suppress the occurrence of development defects.

[0187]

[0188] The structural unit (VII) is roughly classified into two types: (x) a case having an alkali-soluble group, and (y) a case having a group that dissociates under the action of an alkali to increase the solubility in an alkali developer (hereinafter, also simply referred to as an "alkali-dissociable group"). In both (x) and (y), R Ｃ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ｄ is a single bond, a hydrocarbon group having 1 to 20 carbon atoms and a valence of (s+1), and R Ｅ Oxygen atom, sulfur atom, -NR at the end of ｄｄ R has a structure in which -, a carbonyl group, -COO-, -OCO-, or -CONH- is bonded, or a structure in which some of the hydrogen atoms in this hydrocarbon group are substituted with an organic group having a hetero atom. ｄｄ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. s is an integer of 1 to 3.

[0189] When the structural unit (VII) has (x) an alkali-soluble group, R Ｆ is a hydrogen atom, and A １ is an oxygen atom, -COO-* or -SO ２ O-*. * is R Ｆ The binding site of W is shown. １ represents a single bond, a hydrocarbon group having 1 to 20 carbon atoms, or a divalent fluorinated hydrocarbon group. １ is an oxygen atom, W １ is A １ is a fluorinated hydrocarbon group having a fluorine atom or a fluoroalkyl group on the carbon atom to which R is bonded. Ｅ is a single bond or a divalent organic group having 1 to 20 carbon atoms. When s is 2 or 3, multiple R Ｅ , W １ , A １ and R Ｆ may be the same or different.

[0190] When the structural unit (VII) has (y) an alkali-dissociable group, R Ｆ is a monovalent organic group having 1 to 30 carbon atoms, and A １ is an oxygen atom, -NR ａａ -, -COO-*, -OCO-* or -SO ２O-*. R ａａ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. * is R Ｆ The binding site of W is shown. １ is a single bond or a divalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. Ｅ is a single bond or a divalent organic group having 1 to 20 carbon atoms. １ is -COO-*, -OCO-* or -SO ２ If O-*, then W １ or R Ｆ is A １ A has a fluorine atom on the carbon atom bonded to or adjacent to the carbon atom. １ is an oxygen atom, W １ , R Ｅ is a single bond, and R Ｄ is a hydrocarbon group having 1 to 20 carbon atoms. Ｅ A carbonyl group is bonded to the end of the R Ｆ is an organic group having a fluorine atom. When s is 2 or 3, a plurality of R Ｅ , W １ , A １ and R Ｆ may be the same or different.

[0191] The high fluorine content polymer may, for example, have the structural units (III) and (V) of the base polymer, if necessary. The content ratio of each structural unit in the high fluorine content polymer, including these, can be appropriately set.

[0192] The lower limit of Mw of the high fluorine content polymer is preferably 2,000, more preferably 3,000, and even more preferably 4,000. The upper limit of Mw is preferably 20,000, more preferably 15,000, still more preferably 10,000, and particularly preferably 8,000.

[0193] The lower limit of the content of the high fluorine content polymer is preferably 0.5 parts by mass, more preferably 1 part by mass, and even more preferably 3 parts by mass, relative to 100 parts by mass of the radiation-sensitive acid-generating polymer, and the upper limit of the content is preferably 15 parts by mass, more preferably 12 parts by mass, and even more preferably 10 parts by mass.

[0194] The radiation-sensitive composition may contain one or more high-fluorine-containing polymers.

[0195] <Radiation-Sensitive Acid Generator> The radiation-sensitive composition of this embodiment may further contain a radiation-sensitive acid generator that generates an acid upon irradiation (exposure) with radiation. When the base polymer contains the structural unit (IA-1) or the structural unit (III) having an acid-dissociable group, the acid generated from the radiation-sensitive acid generator upon exposure can dissociate the acid-dissociable group of the structural unit (IA-1) or the structural unit (III) to generate a carboxy group or the like. The radiation-sensitive acid generator is preferably contained in the radiation-sensitive composition in a form that exists as a compound by itself (i.e., liberated from the polymer).

[0196] When the radiation-sensitive composition contains the radiation-sensitive acid generator, the polarity of the polymer in the exposed area increases, and the polymer in the exposed area becomes soluble in a developer in the case of development with an aqueous alkali solution, while becoming poorly soluble in the developer in the case of development with an organic solvent.

[0197] Examples of the radiation-sensitive acid generator include onium salts, sulfonimide compounds, halogen-containing compounds, diazoketone compounds, etc. As the onium salt, an onium salt having an organic acid anion and an onium cation is preferred, and examples thereof include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, pyridinium salts, etc. Of these, sulfonium salts and iodonium salts are preferred.

[0198] The acid generated upon exposure is preferably one that generates a sulfonic acid upon exposure. Examples of such acids include compounds in which one or more fluorine atoms or fluorinated hydrocarbon groups are substituted on the carbon atom at the α- or β-position relative to the sulfo group. Among these, the acid anion of the radiation-sensitive acid generator is particularly preferably one having a cyclic structure such as an alicyclic hydrocarbon, an aromatic hydrocarbon, or a structure in which a carbon atom constituting the ring of such a hydrocarbon is substituted with the above-mentioned divalent heteroatom-containing group, or a structure in which such a cyclic structure is combined with the above-mentioned divalent heteroatom-containing group.

[0199] Examples of organic acid anions of the radiation-sensitive acid generator include, but are not limited to, those shown below. Note that the iodo group in the following formula may be substituted with an atom or group other than the iodo group, such as a hydrogen atom or another substituent.

[0200]

[0201]

[0202]

[0203]

[0204] The onium cation contained in the radiation-sensitive acid generator is R 1 of the structural unit (IA) in the base polymer. １ Z shown in ＋ Onium cations represented by the following formula can be preferably used.

[0205] The above-mentioned radiation-sensitive acid generator can be synthesized by a known method, particularly by a salt exchange reaction. Known radiation-sensitive acid generators can also be used as long as they do not impair the effects of the present invention.

[0206] These radiation-sensitive acid generators may be used alone or in combination of two or more. When the radiation-sensitive composition contains a radiation-sensitive acid generator, the lower limit of the content of the radiation-sensitive acid generator (total content when multiple types are used) is preferably 10 parts by mass, more preferably 15 parts by mass, per 100 parts by mass of the base polymer. The upper limit of the content is preferably 50 parts by mass, more preferably 30 parts by mass. This allows excellent sensitivity to be exhibited during resist pattern formation.

[0207] <Acid Diffusion Controller> The radiation-sensitive composition may contain an acid diffusion controller. The acid diffusion controller preferably contains an organic acid anion and an onium cation, and generates an acid having a higher pKa than the acid generated from the radiation-sensitive acid generator upon irradiation with radiation. The acid diffusion controller has the function of substantially not dissociating an acid-dissociable group that the base polymer may have under pattern formation conditions using the radiation-sensitive composition, and of suppressing the diffusion of the acid generated from the radiation-sensitive acid generator in unexposed areas through salt exchange.

[0208] By including the acid diffusion controller in the radiation-sensitive composition, it is possible to suppress the diffusion of acid in unexposed areas, and to form a resist pattern with superior resolution and development contrast.

[0209] The organic acid anion of the acid diffusion controller is preferably a carboxylate anion or a sulfonate anion, more preferably a carboxylate anion. When the organic acid anion of the acid diffusion controller is a sulfonate anion, no electron-withdrawing group is bonded to the carbon atom at the α- or β-position relative to the sulfur atom of the sulfonate anion. The carboxylate anion preferably has a cyclic structure or a divalent heteroatom-containing group as shown in the organic acid anion of the radiation-sensitive acid generator.

[0210] Examples of organic acid anions of the acid diffusion controller include, but are not limited to, those shown below. Examples also include compounds containing an iodonium cation and anion in the same molecule and compounds containing a sulfonium cation and anion in the same molecule. The iodo group in the following formula may be substituted with an atom or group other than an iodo group, such as a hydrogen atom or another substituent.

[0211]

[0212]

[0213] The onium cation in the acid diffusion controller is R １ Z shown in ＋ Onium cations represented by the following formula can be preferably used.

[0214] The acid diffusion controller can also be synthesized by known methods, particularly by salt exchange reaction.

[0215] The acid diffusion controller may be used alone or in combination of two or more. When the composition contains an acid diffusion controller, the lower limit of the content of the acid diffusion controller (total when multiple types are used) is preferably 10 mol %, more preferably 15 mol %, based on the total content of the monomer corresponding to the content ratio of the structural unit (IA-2) of the base polymer and the content of the radiation-sensitive acid generator. The upper limit of the content is preferably 40 mol %, more preferably 30 mol %.

[0216] <Solvent> The radiation-sensitive composition according to this embodiment contains a solvent. The solvent is not particularly limited as long as it can dissolve or disperse the base polymer and, optionally, the radiation-sensitive acid generator, additives, and the like.

[0217] Examples of the solvent include alcohol-based solvents, ether-based solvents, ketone-based solvents, amide-based solvents, ester-based solvents, and hydrocarbon-based solvents.

[0218] Examples of alcohol-based solvents include monoalcohol-based solvents having 1 to 18 carbon atoms, such as isopropanol, 4-methyl-2-pentanol, 3-methoxybutanol, n-hexanol, 2-ethylhexanol, furfuryl alcohol, cyclohexanol, 3,3,5-trimethylcyclohexanol, and diacetone alcohol; polyhydric alcohol-based solvents having 2 to 18 carbon atoms, such as ethylene glycol, 1,2-propylene glycol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol; and polyhydric alcohol partial ether-based solvents in which some of the hydroxy groups in the above-mentioned polyhydric alcohol-based solvents are etherified. In this embodiment, alcohol-based solvents also include alcohol acid ester-based solvents, such as methyl lactate, ethyl lactate, propyl lactate, butyl lactate, methyl 2-hydroxyisobutyrate, isopropyl 2-hydroxyisobutyrate, isobutyl 2-hydroxyisobutyrate, and n-butyl 2-hydroxyisobutyrate.

[0219] Examples of ether-based solvents include dialkyl ether-based solvents such as diethyl ether, dipropyl ether, and dibutyl ether; cyclic ether-based solvents such as tetrahydrofuran and tetrahydropyran; aromatic ring-containing ether-based solvents such as diphenyl ether and anisole (methyl phenyl ether); and polyhydric alcohol ether-based solvents in which the hydroxy groups of the above-mentioned polyhydric alcohol-based solvents have been etherified, such as propylene glycol monomethyl ether (1-methoxy-2-propanol).

[0220] Examples of the ketone solvent include chain ketone solvents such as acetone, butanone, and methyl isobutyl ketone; cyclic ketone solvents such as cyclopentanone, cyclohexanone, and methylcyclohexanone; and 2,4-pentanedione, acetonylacetone, and acetophenone.

[0221] Examples of the amide solvent include cyclic amide solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; and chain amide solvents such as N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, and N-methylpropionamide.

[0222] Examples of ester-based solvents include monocarboxylic acid ester-based solvents such as n-butyl acetate; polyhydric alcohol partial ether acetate-based solvents such as diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate; lactone-based solvents such as γ-butyrolactone and valerolactone; carbonate-based solvents such as diethyl carbonate, ethylene carbonate, and propylene carbonate; and polyvalent carboxylic acid diester-based solvents such as propylene glycol diacetate, methoxytriglycol acetate, diethyl oxalate, ethyl acetoacetate, and diethyl phthalate.

[0223] Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents such as n-hexane, cyclohexane, and methylcyclohexane; and aromatic hydrocarbon solvents such as benzene, toluene, diisopropylbenzene, and n-amylnaphthalene.

[0224] Among these, ester-based solvents and ether-based solvents are preferred, polyhydric alcohol partial ether acetate-based solvents and polyhydric alcohol partial ether-based solvents are more preferred, and propylene glycol monomethyl ether acetate and propylene glycol monomethyl ether are even more preferred. The radiation-sensitive composition may contain one or more solvents.

[0225] <Other Optional Components> The radiation-sensitive composition may contain other optional components in addition to the components described above. Examples of the other optional components include a crosslinking agent, a localization promoter, a surfactant, an alicyclic skeleton-containing compound, and a sensitizer. These other optional components may be used alone or in combination of two or more.

[0226] <Method for Preparing Radiation-Sensitive Composition> The radiation-sensitive composition can be prepared, for example, by mixing a base polymer, a solvent, and, if necessary, other optional components in a predetermined ratio. After mixing, the radiation-sensitive composition is preferably filtered, for example, through a filter having a pore size of approximately 0.05 μm to 0.4 μm. The solids concentration of the radiation-sensitive composition is usually 0.1% by mass to 50% by mass, preferably 0.5% by mass to 30% by mass, and more preferably 1% by mass to 20% by mass.

[0227] <Pattern Forming Method> The pattern forming method of the present embodiment includes: a step (1) of applying the radiation-sensitive composition directly or indirectly to a substrate to form a resist film (hereinafter also referred to as a "resist film forming step"); a step (2) of exposing the resist film to light (hereinafter also referred to as an "exposure step"); and a step (3) of developing the exposed resist film with a developer (hereinafter also referred to as a "development step").

[0228] According to the pattern formation method, the radiation-sensitive composition is used, which is capable of exhibiting excellent sensitivity, CDU, and suppression of development defects during pattern formation, and therefore a high-quality resist pattern can be efficiently formed. Each step will be described below.

[0229] [Resist Film Forming Step] In this step (step (1) above), a resist film is formed from the radiation-sensitive composition. Examples of substrates on which the resist film is formed include conventionally known substrates such as silicon wafers, silicon dioxide wafers, and aluminum-coated wafers. Alternatively, an organic or inorganic anti-reflective coating, such as those disclosed in JP-B-6-12452 and JP-A-59-93448, may be formed on the substrate. Examples of coating methods include spin coating, casting coating, and roll coating. After coating, soft baking (SB) may be performed, if necessary, to volatilize the solvent in the coating film. The SB temperature is typically 60°C to 160°C, preferably 80°C to 140°C. The PB time is typically 5 seconds to 600 seconds, preferably 10 seconds to 300 seconds. The thickness of the resist film formed is preferably 10 nm to 1,000 nm, more preferably 10 nm to 500 nm.

[0230] When the subsequent exposure step is carried out using radiation with a wavelength of 50 nm or less, it is preferable to use a polymer having the structural unit (II) as the base polymer in the composition.

[0231] [Exposure Step] In this step (the above step (2)), the resist film formed in the above step (1), the resist film formation step, is irradiated with radiation through a photomask to expose it. Examples of radiation used for exposure include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV (extreme ultraviolet light), X-rays, and gamma rays; and charged particle beams such as electron beams and alpha rays, depending on the line width of the desired pattern. Among these, far ultraviolet light, electron beams, and EUV are preferred, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), electron beams, and EUV are more preferred, and electron beams and EUV with wavelengths of 50 nm or less, which are positioned as next-generation exposure technologies, are even more preferred.

[0232] After the exposure, post-exposure baking (PEB) is preferably performed to promote dissociation of acid-dissociable groups in the polymer or the like in the exposed portions of the resist film by the acid generated from the radiation-sensitive acid generator upon exposure. This PEB results in a difference in solubility in a developer between the exposed and unexposed portions. The PEB temperature is typically 50°C to 180°C, preferably 80°C to 150°C. The PEB time is typically 5 seconds to 600 seconds, preferably 10 seconds to 300 seconds.

[0233] [Development Step] In this step (step (3) above), the resist film exposed in the exposure step (step (2) above) is developed with a developer. This allows a predetermined resist pattern to be formed. After development, the resist film is generally washed with a rinse liquid such as water or alcohol, and then dried.

[0234] In the case of alkaline development, the developer used in the development may be, for example, an alkaline aqueous solution containing at least one alkaline compound dissolved therein, such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, 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.

[0235] In the case of organic solvent development, examples of the organic solvent include hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, and alcohol solvents, as well as solvents containing an organic solvent. Examples of the organic solvent include one or more of the solvents listed above as solvents for the radiation-sensitive composition. Among these, ester solvents and ketone solvents are preferred. As the ester solvent, acetate ester solvents are preferred, with n-butyl acetate and amyl acetate being more preferred. As the ketone solvent, chain ketones are preferred, with 2-heptanone being more preferred. The content of the organic solvent in the developer is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more. Examples of components other than the organic solvent in the developer include water and silicone oil.

[0236] Examples of the developing method include a method of immersing a substrate in a tank filled with a developer for a certain period of time (dip method), a method of piling up a developer on the surface of the substrate by surface tension and leaving it to stand for a certain period of time to develop (puddle method), a method of spraying the developer onto the surface of the substrate (spray method), and a method of continuously discharging the developer while scanning a developer discharging nozzle at a constant speed onto a substrate that is rotating at a constant speed (dynamic dispense method).

[0237] <Polymer> The polymer according to this embodiment is a polymer including at least one structural unit selected from the group consisting of a structural unit (IA) represented by the following formula (1A) and a structural unit (IB) represented by the following formula (1B): (In formulas (1A) and (1B), R α is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ａ is a single bond or a divalent linking group. Ar is a (p+q+r+s+1)-valent aromatic ring having 3 to 20 carbon atoms. R １ is an acid-dissociable group or —SO ３ - Z ＋ R is a monovalent organic group having 1 to 20 carbon atoms and containing ２is a hydrogen atom or a monovalent organic group having 6 to 20 carbon atoms and a phenolic hydroxyl group. ３ is a fluoro group, a chloro group, a bromo group, a nitro group, a sulfanyl group, an amino group, a cyano group, a carboxy group, or a monovalent organic group having 1 to 20 carbon atoms. p is an integer of 1 to 3. q and r are each independently 1 or 2. s is an integer of 0 to 3. R １ , R ２ and R ３ When there are multiple R １ , R ２ and R ３ are the same or different. ＋ is a monovalent onium cation. １ is an acid-dissociable group, the carbon atom in Ar to which the iodo group is bonded and —OR ２ The carbon atoms in Ar to which the groups are attached are directly bonded to each other.

[0238] As such a polymer, the base polymer in the radiation-sensitive composition can be suitably used.

[0239] <<Compound>> The compound according to this embodiment is a compound represented by the following formula (1a) or (1b). (In formulas (1a) and (1b), R α is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ａ is a single bond or a divalent linking group. Ar is a (p+q+r+s+1)-valent aromatic ring having 3 to 20 carbon atoms. R １ is an acid-dissociable group or —SO ３ - Z ＋ R is a monovalent organic group having 1 to 20 carbon atoms and containing ２ is a hydrogen atom or a monovalent organic group having 6 to 20 carbon atoms and a phenolic hydroxyl group. ３is a fluoro group, a chloro group, a bromo group, a nitro group, a sulfanyl group, an amino group, a cyano group, a carboxy group, or a monovalent organic group having 1 to 20 carbon atoms. p is an integer of 1 to 3. q and r are each independently 1 or 2. s is an integer of 0 to 3. R １ , R ２ and R ３ When there are multiple R １ , R ２ and R ３ are the same or different. ＋ is a monovalent onium cation. １ is an acid-dissociable group, the carbon atom in Ar to which the iodo group is bonded and —OR ２ The carbon atoms in Ar to which the groups are attached are directly bonded to each other.

[0240] As such a compound, a monomer compound that provides the structural unit (I) contained in the base polymer in the radiation-sensitive composition can be suitably used.

[0241] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. Various physical properties in the examples and comparative examples were measured by the following methods.

[0242] [Weight-average molecular weight (Mw) and number-average molecular weight (Mn)] Measurements were performed by gel permeation chromatography (GPC) using Tosoh GPC columns (2 G2000HXL, 1 G3000HXL, 1 G4000HXL) under the following analytical conditions: flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran, sample concentration: 1.0 mass%, sample injection volume: 100 μL, column temperature: 40 ° C., detector: differential refractometer, using monodisperse polystyrene as the standard. The dispersity (Mw / Mn) was calculated from the measurement results of Mw and Mn.

[0243] [ １ H-NMR analysis of polymer １ The H-NMR analysis was carried out using a nuclear magnetic resonance spectrometer (JNM-Delta400 manufactured by JEOL Ltd.).

[0244] <[A] Synthesis of Compound (Monomer)> [Example A-1: ​​Synthesis of Compound Represented by Formula (A-1)] The compound represented by formula (A-1) was synthesized according to the following synthesis scheme.

[0245]

[0246] The compound represented by formula (Z-1) (267 mmol), methyltriphenylphosphonium bromide (669 mmol), and tetrahydrofuran (500 mL) were added to a reaction vessel and cooled to 0°C. Potassium t-butoxide (669 mmol) was added, followed by stirring at room temperature for 5 hours. The reaction solution was then filtered, and a saturated aqueous ammonium chloride solution was added, followed by extraction with ethyl acetate. The resulting organic layer was washed with water and dried over sodium sulfate. The solvent was then distilled off, and the residue was purified by column chromatography to obtain the compound represented by formula (Z-2) in good yield.

[0247] The compound represented by formula (Z-2) (154 mmol), N,N-dimethylaminopyridine (DMAP) (15.4 mmol), and t-butyl alcohol (154 mL) were mixed and stirred at room temperature. Next, a solution of N,N'-dicyclohexylcarbodiimide (DCC) (169 mmol) in tetrahydrofuran (384 mL) was added dropwise over 1 hour. After the addition was completed, the mixture was stirred at 70°C for an additional 10 hours, and then methylene chloride (500 mL) was added and filtered, and the solvent in the filtrate was distilled off. The mixture was purified by silica gel column chromatography to obtain the compound represented by formula (A-1) in good yield.

[0248] [Examples A-2 to A-21 and Comparative Examples A-22 to A-24: Synthesis of Compounds Represented by Formulas (A-2) to (A-21) and (cA-22) to (cA-24)] Compounds represented by the following formulas (A-2) to (A-21) and (cA-22) to (cA-24) were synthesized in the same manner as in Example A-1, except that the raw materials and precursors were changed appropriately.

[0249]

[0250]

[0251] <Synthesis of Compound (Monomer) [B]> [Example B-1: Synthesis of Compound Represented by Formula (B-1)] The compound represented by formula (B-1) was synthesized according to the following synthesis scheme.

[0252]

[0253] The compound represented by formula (Z-2) (20 mmol) and dichloromethane (100 mL) were added to a reaction vessel and cooled to 0°C. 1,1'-carbonylbis-1H-imidazole (30 mmol) and the compound represented by formula (Z-3) (30 mmol) were added, and the mixture was allowed to return to room temperature and stirred. The organic layer was washed twice with an aqueous ammonium chloride solution. The organic layer was dried over sodium sulfate and filtered. The solvent was distilled off, and the mixture was isolated by column chromatography to obtain the compound represented by formula (B-1).

[0254] [Examples B-2 to B-7 and Comparative Examples B-8 to B-9: Synthesis of Compounds Represented by Formulae (B-2) to (B-7) and (cB-8) to (cB-9)] Compounds represented by the following formulae (B-2) to (B-7) and (cB-8) to (cB-9) were synthesized in the same manner as in Example B-1, except that the raw materials and precursors were changed appropriately.

[0255]

[0256]

[0257] <[C] Synthesis of Compound (Monomer)> [Example C-1: Synthesis of Compound Represented by Formula (C-1)] The compound represented by formula (C-1) was synthesized according to the following synthesis scheme.

[0258]

[0259] The compound represented by formula (Z-2) (20 mmol), the compound represented by formula (Z-4) (20 mmol), dichloromethane (100 mL), water (100 mL), and sodium bicarbonate (30 mmol) were added to a reaction vessel and stirred at room temperature. The organic layer was washed twice with water. The organic layer was dried over sodium sulfate and filtered. The solvent was evaporated to obtain the compound represented by formula (C-1).

[0260] [Examples C-2 to C-3 and Comparative Example C-4: Synthesis of Compounds Represented by Formulae (C-2) to (C-3) and (cC-4)] Compounds represented by the following formulae (C-2) to (C-3) and (cC-4) were synthesized in the same manner as in Example C-1, except that the raw materials and precursors were appropriately changed.

[0261]

[0262] Among the monomers used in the synthesis of the polymers in each Example and Comparative Example, the structures of the monomers other than the monomers synthesized above are shown below.

[0263]

[0264] <[P] Polymer Synthesis> [Examples P-1 to P-52 and Comparative Examples P-53 to P-63: Synthesis of Polymers (P-1) to (P-52) and (CP-1) to (CP-11)] Each monomer was combined and copolymerized in 1-methoxy-2-propanol (200 parts by mass relative to the total amount of monomers) as a solvent. The cooled polymerization solution was poured into hexane (500 parts by mass relative to the polymerization solution), and the precipitated white powder was filtered off. The filtered white powder was washed twice with 100 parts by mass of hexane relative to the polymerization solution, then filtered off and dissolved in 1-methoxy-2-propanol (300 parts by mass). The polymer was coagulated by dropping the mixture into 500 parts by mass of water, and the resulting solid was filtered off. The mixture was dried at 50°C for 12 hours to obtain white powdery polymers (P-1) to (P-52) and (CP-1) to (CP-11). The resulting polymers had the following compositions: １ The Mw and dispersity (Mw / Mn) were confirmed by H-NMR under the GPC conditions described above. The type and amount of each monomer are shown in Tables 1-1 to 1-3. In the tables below, "-" indicates that the corresponding component was not used. The same applies to the following tables.

[0265]

[0266]

[0267]

[0268] <[F] Synthesis of Highly Fluorine-Containing Polymers> [Polymer Synthesis Examples F-1 to F-2: Synthesis of Polymers (F-1) to (F-2)] Each monomer was combined and copolymerized in a 2-butanone (200 parts by mass) solvent. After the polymerization reaction was completed, the polymer solution was cooled to 30°C or less with water. After replacing the solvent with acetonitrile (400 parts by mass), hexane (100 parts by mass) was added, stirred, and the acetonitrile layer was collected. This procedure was repeated three times. By replacing the solvent with propylene glycol monomethyl ether acetate, solutions of polymers (F-1) to (F-2) were obtained in good yields. The compositions of the obtained polymers were as follows: １ The Mw and dispersity (Mw / Mn) were confirmed by H-NMR under the above-mentioned GPC conditions. The type and amount of each monomer are shown in Table 2.

[0269]

[0270] <Preparation of Radiation-Sensitive Composition> The radiation-sensitive acid generator, acid diffusion controller, and solvent that constitute the radiation-sensitive composition are described below.

[0271] ([D] Radiation-Sensitive Acid Generator) Compounds represented by the following formulae (D-1) to (D-8).

[0272]

[0273] ([E] Acid Diffusion Controller) Compounds represented by the following formulas (E-1) to (E-6).

[0274]

[0275] ([S] Solvent) S-1: Propylene glycol monomethyl ether acetate S-2: Propylene glycol monomethyl ether

[0276] [Preparation of Radiation-Sensitive Compositions] [Examples 1 to 66 and Comparative Examples 1 to 11] (P-1) as a polymer, (D-1) as a radiation-sensitive acid generator, (E-1) as an acid diffusion controller, (F-1) as a high-fluorine-content resin, and (S-1) and (S-2) as solvents were combined and mixed. This mixture was filtered through a membrane filter with a pore size of 0.2 μm to prepare radiation-sensitive compositions (R-1) to (R-66) and (CR-1) to (CR-11). The types and amounts of each component are shown in Tables 3-1 and 3-2. The content of the acid diffusion controller [E] is a value relative to the total 100 mol % of the content of the monomer corresponding to the content of the structural unit (IA-2) of the polymer [P] and the content of the radiation-sensitive acid generator.

[0277]

[0278]

[0279] <Formation of Resist Pattern> Each of the radiation-sensitive compositions prepared above was applied to the surface of a 12-inch silicon wafer on which a 20-nm-thick underlayer film (AL412 (Brewer Science)) had been formed, using a spin coater (CLEAN TRACK ACT12, Tokyo Electron). After soft baking (SB) at 100°C for 60 seconds, the wafer was cooled at 23°C for 30 seconds to form a 30-nm-thick resist film. This resist film was irradiated with EUV light using an EUV exposure machine (model "NXE3300," ASML, NA=0.33, illumination conditions: Conventional s=0.89). The resist film was then post-exposure baked (PEB) at 100°C for 60 seconds. Next, development was carried out using a 2.38 wt % aqueous solution of TMAH at 23° C. for 30 seconds to form a positive-type 50 nm pitch, 25 nm contact hole pattern.

[0280] <Evaluation> The sensitivity, CDU, and number of development defects of each radiation-sensitive composition were evaluated by measuring each of the resist patterns formed above according to the methods described below. A scanning electron microscope (Hitachi High-Technologies Corporation's "CG-5000") was used to measure the resist patterns. The evaluation results are shown in Table 5 below.

[0281] [Sensitivity] In forming the resist pattern, the exposure dose for forming a 25 nm contact hole pattern was defined as the optimum exposure dose, and this optimum exposure dose was used as the sensitivity (mJ / cm ２ The smaller the value, the better the sensitivity. The sensitivity was 32 mJ / cm ２ If it is less than 32 mJ / cm, it is "A" (very good). ２ 35mJ / cm or more ２ Below "B" (good), 35 mJ / cm ２ If it exceeded this, it was judged as "C" (poor).

[0282] [CDU] A 25 nm contact hole pattern was formed by irradiating the resist with the optimal exposure dose determined in the sensitivity evaluation. The formed resist pattern was observed from above using the scanning electron microscope described above. The hole diameter variation was measured at a total of 600 points, and a 3 sigma value was calculated from the distribution of the measured values. This 3 sigma value was designated as CDU (nm). The smaller the CDU value, the smaller the long-period hole diameter variation and the better the result. CDU was evaluated as "A" (very good) for values ​​less than 2.4 nm, "B" (good) for values ​​between 2.4 nm and 2.7 nm, and "C" (poor) for values ​​greater than 2.7 nm.

[0283] [Number of Development Defects] A resist film was exposed to an optimal exposure dose to form a 25 nm contact hole pattern, which was used as a wafer for defect inspection. The number of defects on this wafer for defect inspection was measured using a defect inspection device (KLA-Tencor's "KLA2810"). Of the measured defects, defects with a diameter of 0.5 μm or less were determined to be originating from the resist film. The number of development defects was evaluated as "A" (very good) when the number of defects determined to be originating from the resist film was less than 30, "B" (good) when the number was 30 to 50, and "C" (poor) when the number was more than 50.

[0284]

[0285]

[0286] The radiation-sensitive composition, pattern forming method, polymer, and compound of the present invention can improve sensitivity, CDU, and the number of development defects compared to conventional methods, and therefore can be suitably used for forming fine resist patterns in lithography processes for various electronic devices such as semiconductor devices and liquid crystal devices.

Claims

1. A radiation-sensitive composition comprising: a polymer containing at least one structural unit selected from the group consisting of a structural unit (IA) represented by the following formula (1A) and a structural unit (IB) represented by the following formula (1B); and a solvent. (In formulas (1A) and (1B), R α is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ａ is a single bond or a divalent linking group. Ar is a (p+q+r+s+1)-valent aromatic ring having 3 to 20 carbon atoms. R １ is an acid-dissociable group or —SO ３ - Z ＋ R is a monovalent organic group having 1 to 20 carbon atoms and containing ２ is a hydrogen atom or a monovalent organic group having 6 to 20 carbon atoms and a phenolic hydroxyl group. ３ is a fluoro group, a chloro group, a bromo group, a nitro group, a sulfanyl group, an amino group, a cyano group, a carboxy group, or a monovalent organic group having 1 to 20 carbon atoms. p is an integer of 1 to 3. q and r are each independently 1 or 2. s is an integer of 0 to 3. R １ , R ２ and R ３ When there are multiple R １ , R ２ and R ３ are the same or different. ＋ is a monovalent onium cation. １ is an acid-dissociable group, the carbon atom in Ar to which the iodo group is bonded and —OR ２ The carbon atoms in Ar to which the groups are attached are directly bonded to each other.

2. The radiation-sensitive composition according to claim 1, wherein in the formulae (1A) and (1B), the aromatic ring is a benzene ring.

3. In the above formulas (1A) and (1B), L Ａ is a single bond or -COO- ＊ 2. The radiation-sensitive composition according to claim 1, wherein * represents a bond on the Ar side.

4. In the above formula (1A), R １ The radiation-sensitive composition according to claim 1 , wherein is an acid-dissociable group.

5. In formula (1B), Z ＋ The radiation-sensitive composition according to claim 1 , wherein is a sulfonium cation or an iodonium cation.

6. The radiation-sensitive composition according to claim 1, wherein the structural unit (IA) is represented by the following formula (1A-1) or (1A-2), and the structural unit (IB) is represented by the following formula (1B-1). (In formulas (1A-1), (1A-2) and (1B-1), R α , R ２ , R ３ and p have the same meanings as in formula (1A). ａ is a single bond or -COO- ＊ * indicates a bond on the benzene ring side. R ８ R is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. ９ and R １０ are each independently a hydrogen atom, a substituted or unsubstituted monovalent chain hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or a substituted or unsubstituted divalent alicyclic group having 3 to 20 carbon atoms formed by combining these groups together with the carbon atoms to which they are bonded. ９ and R １０ There is no case where both of R are hydrogen atoms. ９ or R １０ When one of R is a hydrogen atom, ８ is a substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms. ｂ -SO ３ - is a divalent linking group having 2 to 20 carbon atoms in which an electron-withdrawing group is bonded to the carbon atom at the α- or β-position relative to the sulfur atom in １ ＋ is a sulfonium cation or an iodonium cation.

7. The polymer is R of the formula (1A) １ 2. The radiation-sensitive composition according to claim 1, wherein, when the structural unit (IA) is an acid-dissociable group, the content of the structural unit (IA) in all structural units constituting the polymer is 10 mol % or more and 100 mol % or less.

8. The polymer is R of the formula (1A) １ Ga-SO ３ - Z ＋ 2. The radiation-sensitive composition according to claim 1, wherein when the radiation-sensitive composition contains a structural unit (IA) that is a monovalent organic group having 1 to 20 carbon atoms and that contains the following structural unit (IA), the content of the structural unit (IA) in all structural units constituting the polymer is 2 mol % or more and 20 mol % or less.

9. The radiation-sensitive composition according to claim 1, wherein, when the polymer contains the structural unit (IB), the content of the structural unit (IB) in all structural units constituting the polymer is 1 mol % or more and 10 mol % or less.

10. The radiation-sensitive composition according to claim 1, wherein the polymer further contains a structural unit having a phenolic hydroxyl group (excluding the structural units (IA) and (IB)).

11. The radiation-sensitive composition according to claim 1, wherein the polymer further contains a structural unit (excluding the structural unit (IA)) having an acid-dissociable group.

12. The radiation-sensitive composition of claim 1, further comprising a radiation-sensitive acid generator.

13. The radiation-sensitive composition according to claim 1, further comprising an acid diffusion controller.

14. A pattern forming method comprising the steps of: applying the radiation-sensitive composition according to any one of claims 1 to 13 directly or indirectly to a substrate to form a resist film; exposing the resist film; and developing the exposed resist film with a developer.

15. The pattern forming method according to claim 14, wherein the exposure is carried out with extreme ultraviolet rays or electron beams.

16. A polymer comprising at least one structural unit selected from the group consisting of a structural unit (IA) represented by the following formula (1A) and a structural unit (IB) represented by the following formula (1B): (In formulas (1A) and (1B), R α is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ａ is a single bond or a divalent linking group. Ar is a (p+q+r+s+1)-valent aromatic ring having 3 to 20 carbon atoms. R １ is an acid-dissociable group or —SO ３ - Z ＋ R is a monovalent organic group having 1 to 20 carbon atoms and containing ２ is a hydrogen atom or a monovalent organic group having 6 to 20 carbon atoms and a phenolic hydroxyl group. ３ is a fluoro group, a chloro group, a bromo group, a nitro group, a sulfanyl group, an amino group, a cyano group, a carboxy group, or a monovalent organic group having 1 to 20 carbon atoms. p is an integer of 1 to 3. q and r are each independently 1 or 2. s is an integer of 0 to 3. R １ , R ２ and R ３ When there are multiple R １ , R ２ and R ３ are the same or different. ＋ is a monovalent onium cation. １ is an acid-dissociable group, the carbon atom in Ar to which the iodo group is bonded and —OR ２ The carbon atoms in Ar to which the groups are attached are directly bonded to each other.

17. A compound represented by the following formula (1a) or (1b): (In formulas (1a) and (1b), R α is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ａ is a single bond or a divalent linking group. Ar is a (p+q+r+s+1)-valent aromatic ring having 3 to 20 carbon atoms. R １ is an acid-dissociable group or —SO ３ - Z ＋ R is a monovalent organic group having 1 to 20 carbon atoms and containing ２ is a hydrogen atom or a monovalent organic group having 6 to 20 carbon atoms and a phenolic hydroxyl group. ３ is a fluoro group, a chloro group, a bromo group, a nitro group, a sulfanyl group, an amino group, a cyano group, a carboxy group, or a monovalent organic group having 1 to 20 carbon atoms. p is an integer of 1 to 3. q and r are each independently 1 or 2. s is an integer of 0 to 3. R １ , R ２ and R ３ When there are multiple R １ , R ２ and R ３ are the same or different. ＋ is a monovalent onium cation. １ is an acid-dissociable group, the carbon atom in Ar to which the iodo group is bonded and —OR ２ The carbon atoms in Ar to which the groups are attached are directly bonded to each other.

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