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

Abstract

This radiation-sensitive composition comprises: a polymer of which the solubility in a development liquid changes due to the action of an acid; and a compound which has a sulfonate anion and a radiation-sensitive onium cation. The sulfonate anion has: an aromatic ring in which at least one hydrogen atom is substituted with a substituent; and at least one group selected from the group consisting of a hydroxy group and a carboxy group. The substituent is at least one group selected from the group consisting of fluorinated alkyl groups, unsubstituted tertiary alkyl groups, and trialkylsilyl groups. The radiation-sensitive onium cation has an aromatic ring in which at least one hydrogen atom is substituted with a fluoro group or a fluorinated alkyl group.

Description

Radiation-sensitive composition, method for forming resist pattern, and compound

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

[0002] Radiation-sensitive compositions used in microfabrication by lithography generate an acid in exposed areas when irradiated with radiation such as far ultraviolet rays such as ArF excimer laser light (wavelength 193 nm) and KrF excimer laser light (wavelength 248 nm), electromagnetic waves such as extreme ultraviolet rays (EUV, wavelength 13.5 nm), or charged particle rays such as electron beams, and a chemical reaction initiated by this acid causes a difference in the dissolution rate in a developer between exposed and unexposed areas, thereby forming a resist pattern on a substrate.

[0003] The radiation-sensitive composition is required to have good sensitivity to radiation such as extreme ultraviolet rays and electron beams, as well as good LWR (Line Width Roughness), resolution, and the like.

[0004] In response to these requirements, the types and molecular structures of polymers, acid generators, and other components used in radiation-sensitive compositions have been investigated, and combinations thereof have also been investigated in detail (see JP-A-2010-134279, JP-A-2014-224984, JP-A-2016-047815, and JP-A-2021-009357).

[0005] JP 2010-134279 A JP 2014-224984 A JP 2016-047815 A JP 2021-009357 A

[0006] As resist patterns become finer, the level of performance required is becoming higher and higher, and there is a demand for radiation-sensitive compositions that satisfy these requirements.

[0007] The present invention has been made in light of the above-mentioned circumstances, and an object of the present invention is to provide a radiation-sensitive composition and a method for forming a resist pattern that have good sensitivity, LWR, and resolution. Another object of the present invention is to provide a compound that is suitable as a radiation-sensitive acid generator to be contained in the radiation-sensitive composition.

[0008] The invention made to solve the above problems provides a radiation-sensitive composition comprising a polymer whose solubility in a developer changes under the action of an acid, and a compound having a sulfonate anion and a radiation-sensitive onium cation, wherein the sulfonate anion has an aromatic ring in which at least one hydrogen atom is substituted with a substituent, and at least one group selected from the group consisting of a hydroxy group and a carboxy group, the substituent being at least one group selected from the group consisting of a fluorinated alkyl group, an unsubstituted tertiary alkyl group, and a trialkylsilyl group, and the radiation-sensitive onium cation has an aromatic ring in which at least one hydrogen atom is substituted with a fluoro group or a fluorinated alkyl group.

[0009] Another invention made to solve the above-mentioned problems is a method for forming a resist pattern, comprising the steps of applying the radiation-sensitive composition described above directly or indirectly to a substrate, exposing the resist film formed by the application to light, and developing the exposed resist film.

[0010] Yet another invention made to solve the above-mentioned problems is a compound having a sulfonate anion and a radiation-sensitive onium cation, wherein the sulfonate anion has an aromatic ring in which at least one hydrogen atom is substituted with a substituent, and at least one group selected from the group consisting of a hydroxy group and a carboxy group, and the substituent is at least one group selected from the group consisting of a fluorinated alkyl group, an unsubstituted tertiary alkyl group, and a trialkylsilyl group, and the radiation-sensitive onium cation is a compound having an aromatic ring in which at least one hydrogen atom is substituted with a fluoro group or a fluorinated alkyl group.

[0011] The radiation-sensitive composition of the present invention has good sensitivity, LWR, and resolution. According to the method for forming a resist pattern of the present invention, a resist pattern having good sensitivity, LWR, and resolution can be formed. The compound of the present invention is suitable as a radiation-sensitive acid generator contained in the radiation-sensitive composition. Therefore, these compounds can be suitably used in the processing of semiconductor devices, which are expected to become even more miniaturized in the future.

[0012] The radiation-sensitive composition, method of forming a resist pattern, and compound of the present invention will be described in detail below.

[0013] Unless otherwise specified, the description of the upper and lower limits of a numerical range in this specification may be "less than or equal to" or "less than," and the lower limit may be "greater than or equal to" or "greater than." The upper and lower limits may be any combination of the disclosed numerical values. When a numerical range is indicated using the symbol "to," it means that the numerical range includes the upper and lower limit numerical values. For example, "1 to 20 carbon atoms" means "1 to 20 carbon atoms inclusive."

[0014] <Radiation-Sensitive Composition> The radiation-sensitive composition contains a polymer whose solubility in a developer changes under the action of an acid (hereinafter also referred to as "polymer [A]"), and a compound having a specific sulfonate anion described below and a specific radiation-sensitive onium cation described below (hereinafter also referred to as "compound [Z]"). The sulfonate anion has an aromatic ring in which at least one hydrogen atom is substituted with a substituent, and at least one group selected from the group consisting of a hydroxy group and a carboxy group. The substituent is at least one group selected from the group consisting of a fluorinated alkyl group, an unsubstituted tertiary alkyl group, and a trialkylsilyl group. The radiation-sensitive onium cation has an aromatic ring in which at least one hydrogen atom is substituted with a fluoro group or a fluorinated alkyl group.

[0015] The radiation-sensitive composition has the above-described structure, which provides the effect of excellent sensitivity, LWR, and resolution. The reasons for this are not entirely clear, but are presumed to be, for example, as follows: First, it is believed that the sulfonate anion has an aromatic ring with a specific substituent, which optimizes the distribution of the compound [Z] in the resist film. Second, it is believed that the sulfonate anion has a specific hydrophilic group, which contributes to high solubility. Third, it is believed that the radiation-sensitive onium cation has an aromatic ring substituted with a fluoro group or the like, which lowers the lowest unoccupied molecular orbital of the cation, thereby increasing acid generation efficiency. The radiation-sensitive composition has the above-described structure, which combines the above effects to provide a good balance between sensitivity, LWR, and resolution.

[0016] The radiation-sensitive composition usually contains an organic solvent (hereinafter also referred to as "organic solvent [E]"). The radiation-sensitive composition may contain a radiation-sensitive acid generator other than the compound [Z]. For example, when the polymer [A] has a structural unit containing a group that generates a sulfonic acid upon the action of radiation, an example of the radiation-sensitive acid generator is the polymer [A] itself. Furthermore, as a component other than the polymer [A], a radiation-sensitive acid generator (hereinafter also referred to as "acid generator [B]") may be used. The radiation-sensitive composition may also contain an acid diffusion controller. For example, when the polymer [A] has a structural unit containing a group that generates a carboxylic acid upon the action of radiation, an example of the acid diffusion controller is the polymer [A] itself. Furthermore, as a component other than the polymer [A], an acid diffusion controller (hereinafter also referred to as "acid diffusion controller [C]") may be used. The radiation-sensitive composition may also contain a carboxy group-containing compound (hereinafter also referred to as "compound [D]"). The radiation-sensitive composition may contain a polymer (hereinafter also referred to as "polymer [F]") having a higher fluorine atom content than the polymer [A]. The radiation-sensitive composition may contain other optional components as long as the effects of the present invention are not impaired.

[0017] The radiation-sensitive composition can be prepared, for example, by mixing the polymer (A) and the compound (Z), and, if necessary, the acid diffusion controller (C), the compound (D), the organic solvent (E), and other optional components in a predetermined ratio, and filtering the resulting mixture through a membrane filter having a pore size of 0.2 μm or less.

[0018] Each component contained in the radiation-sensitive composition will be described below.

[0019] <Polymer (A)> The polymer (A) is a polymer whose solubility in a developer changes under the action of an acid. The radiation-sensitive composition may contain one or more types of polymer (A).

[0020] The polymer [A] usually has a structural unit containing an acid-dissociable group (hereinafter also referred to as "structural unit (Ia)"). The polymer [A] preferably has a structural unit containing a phenolic hydroxyl group (hereinafter also simply referred to as "structural unit (IIa)").

[0021] The polymer (A) may further have other structural units (hereinafter simply referred to as "other structural units") other than the structural units (I) and (II). The polymer (A) may have one or more types of each structural unit.

[0022] The other structural units are structural units other than the structural units (Ia) and (IIa). Examples of the other structural units include a structural unit containing a polar group (hereinafter also referred to as "structural unit (IIIa)") and a structural unit containing a group that generates an acid when exposed to radiation (hereinafter also referred to as "structural unit (IVa)").

[0023] In this specification, the term "structural unit" refers to one of the repeating units obtained by polymerizing a monomer, and is composed of a portion that constitutes a main chain and a side chain. The term "main chain" refers to the longest atomic chain that constitutes a polymer. The term "side chain" refers to an atomic chain other than the main chain that constitutes a polymer.

[0024] The polymer [A] preferably has an iodine group. When the polymer [A] has an iodine group, the sensitivity of the radiation-sensitive composition may be further improved. The polymer [A] preferably has an iodine group on a side chain of the polymer [A]. Examples of embodiments in which the polymer [A] has an iodine group include an embodiment in which the structural unit (Ia) contains an iodine group, an embodiment in which the structural unit (IIa) contains an iodine group, an embodiment in which the structural unit (IIIa) contains an iodine group, an embodiment in which a radiation-sensitive onium cation in the structural unit (IVa), which will be described later, contains an iodine group, and an embodiment in which an anion in the structural unit (IVa), which will be described later, contains an iodine group.

[0025] The lower limit of the content of the polymer (A) in the radiation-sensitive composition is preferably 50% by mass, more preferably 70% by mass, and even more preferably 80% by mass, based on all components other than the organic solvent (D) contained in the radiation-sensitive composition, and the upper limit of the content is preferably 99% by mass, more preferably 95% by mass.

[0026] The lower limit of the weight average molecular weight (Mw) of the polymer [A], as measured by gel permeation chromatography (GPC) in terms of polystyrene, is preferably 1,000, more preferably 2,000, even more preferably 3,000, and still more preferably 5,000. The upper limit of the Mw is preferably 30,000, more preferably 20,000, even more preferably 15,000, and still more preferably 12,000. By setting the Mw of the polymer [A] within the above range, the coatability of the radiation-sensitive composition can be improved. The Mw of the polymer [A] can be adjusted, for example, by adjusting the type and amount of polymerization initiator used in the synthesis of the polymer [A].

[0027] The upper limit of the ratio of Mw to the polystyrene-equivalent number average molecular weight (Mn) of the polymer (A) as determined by GPC (hereinafter also referred to as "Mw / Mn") is preferably 2.5, more preferably 2.0, and even more preferably 1.9. The lower limit of the ratio is usually 1.0, preferably 1.1, and more preferably 1.2.

[0028] [Method for measuring Mw and Mn] The Mw and Mn of the polymer in this specification are values ​​measured using gel permeation chromatography (GPC) under the following conditions: GPC columns: two "G2000HXL" columns, one "G3000HXL" column, and one "G4000HXL" column, all manufactured by Tosoh Corporation; column temperature: 40°C; elution solvent: tetrahydrofuran; flow rate: 1.0 mL / min; sample concentration: 1.0 mass%; sample injection amount: 100 μL; detector: differential refractometer; standard material: monodisperse polystyrene.

[0029] The polymer (A) can be synthesized, for example, by polymerizing monomers that provide the respective structural units by a known method.

[0030] Each structural unit contained in the polymer (A) will be described below.

[0031] [Structural Unit (Ia)] The structural unit (Ia) is a structural unit containing an acid-dissociable group. The "acid-dissociable group" refers to a group that substitutes a hydrogen atom in a carboxy group and dissociates under the action of an acid to give a carboxy group.

[0032] The polymer [A] has a structural unit (Ia) containing an acid-dissociable group, and thereby exhibits a property in which its solubility in a developer changes under the action of an acid. The acid-dissociable group is dissociated by the action of an acid generated from the radiation-sensitive acid generator in response to the action of radiation, resulting in a difference in the solubility of the polymer [A] in a developer between an exposed area and a non-exposed area, and thereby enabling the formation of a resist pattern.

[0033] The acid-dissociable group is a group that substitutes a hydrogen atom of the carboxy group in the structural unit (Ia). In other words, in the structural unit (Ia), the acid-dissociable group is bonded to the etheric oxygen atom of the carbonyloxy group.

[0034] Examples of the acid-dissociable group include groups represented by the following formulae (a-1) and (a-2) (hereinafter also referred to as "acid-dissociable groups (a-1) and (a-2)").

[0035]

[0036] In the above formulas (a-1) and (a-2), * indicates the bonding site of the carbonyloxy group with the etheric oxygen atom.

[0037] In the above formula (a-1), R Ｘ R is a substituted or unsubstituted monovalent chain hydrocarbon group having 1 to 20 carbon atoms, or a group in which one hydrogen atom has been removed from a substituted or unsubstituted aromatic ring having 5 to 20 ring members. Ｙ and R Ｚ are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or these groups are combined with each other to form a saturated alicyclic ring having 3 to 20 ring members together with the carbon atoms to which they are attached.

[0038] In the above formula (a-2), R Ａ and R Ｂ are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or R Ａ and R Ｂ are combined with each other to form an unsaturated alicyclic ring having 3 to 20 ring members together with the carbon atoms to which they are attached. Ｂ has a carbon atom forming a carbon-carbon double bond at the α-position of the carbon atom bonded to *.

[0039] The term "hydrocarbon group" includes "aliphatic hydrocarbon groups" and "aromatic hydrocarbon groups." The term "aliphatic hydrocarbon group" includes "chain hydrocarbon groups" and "alicyclic hydrocarbon groups." From another perspective, the term "aliphatic hydrocarbon group" includes "saturated hydrocarbon groups" and "unsaturated hydrocarbon groups." The term "chain hydrocarbon group" refers to a hydrocarbon group that does not contain a ring structure and is composed only of a chain structure, and includes both straight-chain hydrocarbon groups and branched-chain hydrocarbon groups. The term "alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic ring as a ring structure and does not contain an aromatic ring, and includes both monocyclic alicyclic hydrocarbon groups and polycyclic alicyclic hydrocarbon groups. However, it does not have to be composed only of an alicyclic ring, and may contain a chain structure as part of it. The term "aromatic hydrocarbon group" refers to a hydrocarbon group that contains an aromatic ring as a ring structure. However, it does not have to be composed only of an aromatic ring, and may contain a chain structure or an alicyclic ring as part of it.

[0040] The "number of ring members" refers to the number of atoms constituting the ring structure, and in the case of a polycycle, it refers to the number of atoms constituting the polycycle. "Polycycle" includes not only fused polycycles in which two rings share two common atoms, but also ring assembly polycycles in which two rings do not share a common atom and are connected by a single bond.

[0041] The term "aromatic ring" includes "aromatic hydrocarbon ring" and "aromatic heterocycle." Among aromatic rings, polycyclic rings including aromatic hydrocarbon rings and aromatic heterocycles are considered to be "aromatic heterocycles."

[0042] R Ｘ Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms that gives the formula (I) include alkyl groups such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a sec-butyl group, an isobutyl group, and a tert-butyl group; alkenyl groups such as an ethenyl group, a propenyl group, a butenyl group, and a 2-methylprop-1-en-1-yl group; and alkynyl groups such as an ethynyl group, a propynyl group, and a butynyl group.

[0043] R Ｘ Examples of aromatic rings having 5 to 20 ring members that give the formula include aromatic hydrocarbon rings having 6 to 20 ring members and aromatic heterocyclic rings having 5 to 20 ring members.

[0044] Examples of aromatic hydrocarbon rings having 6 to 20 ring members include a benzene ring; condensed polycyclic aromatic hydrocarbon rings such as a naphthalene ring, an anthracene ring, a fluorene ring, a biphenylene ring, a phenanthrene ring, and a pyrene ring; ring-assembly aromatic hydrocarbon rings such as a biphenyl ring, a terphenyl ring, a binaphthalene ring, and a phenylnaphthalene ring; and a 9,10-ethanoanthracene ring.

[0045] Examples of the aromatic heterocycle having 5 to 20 ring members include oxygen atom-containing heterocycles such as a furan ring, a pyran ring, a benzofuran ring, and a benzopyran ring; nitrogen atom-containing heterocycles such as a pyridine ring, a pyrimidine ring, and an indole ring; and sulfur atom-containing heterocycles such as a thiophene ring.

[0046] R ＸExamples of the substituent that the group represented by the formula (I) may have include a halogeno group such as a fluoro group or an iodo group, a hydroxy group, a carboxy group, a cyano group, a nitro group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, and an acyloxy group.

[0047] R Ｙ , R Ｚ , R Ａ , or R Ｂ Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms that gives the formula (I) include a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms.

[0048] The monovalent chain hydrocarbon group having 1 to 20 carbon atoms includes the above-mentioned R Ｘ Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms that gives the following formula include those given above.

[0049] 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.

[0050] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xylyl, naphthyl, and anthryl; and aralkyl groups such as benzyl, phenethyl, naphthylmethyl, and anthrylmethyl.

[0051] R Ｙ and R Ｚ Among the saturated alicyclic rings having 3 to 20 ring members formed by combining these rings together with the carbon atoms to which they are bonded, examples of the aliphatic hydrocarbon ring include monocyclic rings such as a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, and a cyclohexane ring; and polycyclic rings such as a norbornane ring, an adamantane ring, a tricyclodecane ring, and a tetracyclododecane ring.

[0052] R Ｙ and R Ｚ Among saturated alicyclic rings having 3 to 20 ring members formed by combining these rings together with the carbon atoms to which they are bonded, examples of the aliphatic heterocyclic ring include oxygen atom-containing heterocyclic rings such as tetrahydrofuran ring.

[0053] R Ａ and R Ｂ Examples of the unsaturated alicyclic ring having 3 to 20 ring members formed by combining these together with the carbon atoms to which they are bonded include monocyclic unsaturated alicyclic rings such as a cyclobutene structure, a cyclopentene structure, and a cyclohexene structure, and polycyclic unsaturated alicyclic rings such as a norbornene structure.

[0054] R Ｙ and R Ｚ is a monovalent hydrocarbon group having 1 to 20 carbon atoms, R Ｙ and R Ｚ As R, a chain hydrocarbon group is preferable, an alkyl group is preferable, and a methyl group or an ethyl group is more preferable. Ｘ As the substituted or unsubstituted aromatic ring having 5 to 20 ring members, a group in which one hydrogen atom has been removed is preferred, a group in which one hydrogen atom has been removed from a substituted or unsubstituted aromatic hydrocarbon ring having 6 to 20 ring members is more preferred, and a phenyl group, an iodophenyl group, or a fluorophenyl group is even more preferred.

[0055] R Ｙ and R Ｚ When R are combined with each other to form a saturated alicyclic ring having 3 to 20 ring members together with the carbon atoms to which they are bonded, the saturated alicyclic ring is preferably a cyclopentane ring or a cyclohexane ring. Ｘ As the aryl group, an alkyl group, an alkenyl group, a group in which one hydrogen atom has been removed from a substituted or unsubstituted benzene ring, or a group in which one hydrogen atom has been removed from a substituted or unsubstituted sulfur atom-containing heterocycle is preferred, and a methyl group, an ethenyl group, a phenyl group, an iodophenyl group, or an iodothiophenyl group is more preferred.

[0056] R Ａ and R Ｂ are both monovalent hydrocarbon groups having 1 to 20 carbon atoms, R ＡAs R, a chain hydrocarbon group is preferable, an alkyl group is preferable, and a methyl group is more preferable. Ｂ As the alkyl group, a substituted or unsubstituted aromatic hydrocarbon group is preferable, a substituted or unsubstituted aryl group is more preferable, and an iodophenyl group is even more preferable.

[0057] R Ａ and R Ｂ When these are combined with each other to form an unsaturated alicyclic ring having 3 to 20 ring members together with the carbon atoms to which they are bonded, the unsaturated alicyclic ring is preferably a monocyclic unsaturated alicyclic ring, more preferably a cyclohexene ring.

[0058] Examples of the acid-dissociable group (a-1) include groups represented by the following formulae (a-1-1) to (a-1-9): Examples of the acid-dissociable group (a-2) include groups represented by the following formulae (a-2-1) to (a-2-2):

[0059]

[0060] Examples of the structural unit (Ia) include a structural unit represented by the following formula (Ia):

[0061] In the above formula (Ia), R Ｈ１ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ｈ is a single bond, *-COO- or *-CONH-. * is R Ｈ１ indicates the bonding site with the carbon atom to which R is attached. Ｈ２ R is a single bond, a divalent chain hydrocarbon group having 1 to 10 carbon atoms, or a group in which two hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring having 6 to 20 ring members. Ｈ３ is the acid-dissociable group.

[0062] R Ｈ１ From the viewpoint of copolymerizability of the monomer that gives the structural unit (Ia), a hydrogen atom or a methyl group is preferred.

[0063] L Ｈ is preferably a single bond or *-COO-.

[0064] R Ｈ２Examples of the divalent chain hydrocarbon group having 1 to 10 carbon atoms that gives the formula Ｘ Among the examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms that gives the formula (I), a group in which one hydrogen atom has been removed from a group having 1 to 10 carbon atoms can be mentioned. Ｈ２ The divalent chain hydrocarbon group giving the formula (I) is preferably a methanediyl group.

[0065] R Ｈ２ Examples of aromatic hydrocarbon rings having 6 to 20 ring members that give the formula include the above-mentioned R Ｘ Among aromatic rings having 5 to 20 ring members that give the formula R Ｈ２ As the aromatic hydrocarbon ring which gives the following formula, a benzene ring is preferred.

[0066] R Ｈ２ Examples of the substituent that the aromatic hydrocarbon ring may have include the above-mentioned R Ｘ Examples of the substituent that the group represented by the following formula may have include those exemplified above.

[0067] Specific examples of the structure of the monomer that provides the structural unit (Ia) include the monomers (M-7) to (M-20) in the examples described below.

[0068] The lower limit of the content of the structural unit (Ia) in the polymer [A] is preferably 10 mol %, more preferably 20 mol %, and even more preferably 30 mol %, based on all structural units constituting the polymer [A]. The upper limit of the content is preferably 90 mol %, more preferably 80 mol %, and even more preferably 70 mol %.

[0069] [Structural Unit (IIa)] The structural unit (IIa) is a structural unit containing a phenolic hydroxyl group. The term "phenolic hydroxyl group" refers not only to a hydroxyl group directly bonded to a benzene ring, but also to any hydroxyl group directly bonded to an aromatic ring.

[0070] In the case of KrF exposure, EUV exposure, or electron beam exposure, the polymer (A) having the structural unit (IIa) can further increase the sensitivity of the radiation-sensitive composition, and therefore the radiation-sensitive composition can be suitably used as a radiation-sensitive composition for KrF exposure, EUV exposure, or electron beam exposure.

[0071] Examples of the structural unit (IIa) include a structural unit represented by the following formula (IIa).

[0072]

[0073] In the above formula (IIa), R Ｐ is a hydrogen atom, a fluoro group, a methyl group, or a trifluoromethyl group. Ｐ is a single bond, *-COO-, -O-, or *-CONH-. * is R Ｐ indicates the bonding site with the carbon atom to which Ar is bonded. Ｐ represents a group in which (p+1) hydrogen atoms have been removed from a substituted or unsubstituted aromatic hydrocarbon ring having 6 to 20 ring members, and p is an integer of 1 to 3.

[0074] R Ｐ From the viewpoint of copolymerizability of the monomer that gives the structural unit (IIa), a hydrogen atom or a methyl group is preferred.

[0075] L Ｐ is preferably a single bond or *-COO-.

[0076] Ar Ｐ Examples of aromatic hydrocarbon rings having 6 to 20 ring members that give the formula include the above-mentioned R Ｘ Among aromatic rings having 5 to 20 ring members that give the formula (I), examples of aromatic hydrocarbon rings having 6 to 20 ring members include Ar Ｐ As the aromatic hydrocarbon ring which gives the following formula, a benzene ring is preferred.

[0077] Ar Ｐ Examples of the substituent that the aromatic hydrocarbon ring may have include the above-mentioned R Ｘ Examples of the substituent that the group represented by the following formula may have include those exemplified above.

[0078] As p, 1 or 2 is preferred.

[0079] Examples of the structural unit (IIa) include structural units represented by the following formulae (IIa-1) to (IIa-20).

[0080]

[0081] In the above formulas (IIa-1) to (IIa-20), R Ｐ has the same meaning as in formula (IIa) above.

[0082] Specific examples of the structure of the monomer that provides the structural unit (IIa) include the monomers (M-1) to (M-6) in the examples described below.

[0083] The lower limit of the content of the structural unit (II) in the polymer [A] is preferably 10 mol %, more preferably 20 mol %, based on all structural units constituting the polymer [A].The upper limit of the content is preferably 70 mol %, more preferably 60 mol %.

[0084] [Structural Unit (IIIa)] The structural unit (IIIa) is a structural unit containing a polar group. The polymer (A) has the structural unit (IIIa), so that the solubility in a developer can be appropriately adjusted. Examples of the polar group include a lactone structure, a cyclic carbonate structure, a sultone structure, or a group containing a combination thereof, an alkoxy group, and a fluorinated alcohol group.

[0085] Among the structural units (IIIa), examples of structural units containing a group containing a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination thereof include structural units represented by the following formula:

[0086]

[0087]

[0088]

[0089]

[0090] In the above formula, R Ｌ１ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group.

[0091] Specific examples of the structure of the monomer that provides the structural unit (IIIa) include the monomers (M-31) to (M-34) in the Examples described below. Among these, the monomer (M-31) corresponds to a monomer that provides a structural unit that includes an alkoxy group as a polar group, and the monomers (M-32) to (M-34) correspond to monomers that provide a structural unit that includes a lactone structure, a cyclic carbonate structure, a sultone structure, or a group that includes a combination thereof as a polar group.

[0092] When the polymer [A] contains the structural unit (IIIa), the lower limit of the content of the structural unit (IIIa) is preferably 5 mol %, more preferably 10 mol %, based on all structural units constituting the polymer [A]. The upper limit of the content is preferably 30 mol %, more preferably 20 mol %.

[0093] [Structural Unit (IVa)] The structural unit (IVa) is a structural unit containing a group (hereinafter also referred to as "group (x)") that generates an acid when exposed to radiation. Examples of the radiation include those exemplified as radiation in the section <Method of Forming a Resist Pattern> described below. Examples of the acid that is generated when exposed to radiation include sulfonic acid and carboxylic acid.

[0094] Examples of the group (x) include a structure containing an anion and a radiation-sensitive onium cation. Such structures are classified into a structure in which an anion is bonded to a side chain of a polymer (hereinafter also referred to as "Structure 1") and a structure in which a radiation-sensitive onium cation is bonded to a side chain of a polymer (hereinafter also referred to as "Structure 2"). The group (x) may be either Structure 1 or Structure 2.

[0095] The group (x) is classified according to the type of acid generated by the action of radiation, for example, into a group that generates a sulfonic acid by the action of radiation (hereinafter also referred to as a "group (xa)") and a group that generates a carboxylic acid by the action of radiation (hereinafter also referred to as a "group (xb)").

[0096] The polymer [A] acts as a radiation-sensitive acid generator, an acid diffusion controller, or both in the radiation-sensitive composition, depending on the type of group (x) in the structural unit (IVa). When the structural unit (IVa) has a group (xa), the polymer [A] acts as a radiation-sensitive acid generator in the radiation-sensitive composition. When the structural unit (IVa) has a group (xb), the polymer [A] acts as an acid diffusion controller in the radiation-sensitive composition. When the structural unit (IVa) has a group (xa) and a group (xb), or when the polymer [A] has a structural unit (IVa) having a group (xa) and a structural unit (IVa) having a group (xb), the polymer [A] acts as both a radiation-sensitive acid generator and an acid diffusion controller in the radiation-sensitive composition.

[0097] When the structural unit (IVa) has a group (xb) (i.e., when it has a group that generates a carboxylic acid upon the action of radiation), the polymer [A] can also be broadly referred to as a "radiation-sensitive acid generator." However, the carboxylic acid generated from the group (xb) upon the action of radiation does not dissociate the acid-dissociable group under conditions in which the acid generated from the acid generator [B] or the group (xa) dissociates the acid-dissociable group, and therefore the "radiation-sensitive acid generator" is clearly distinguished from the "acid diffusion controller."

[0098] When the group (x) corresponds to the above structure 1, the structural unit (IVa) may be, for example, a structural unit represented by the following formula (IVa).

[0099]

[0100] In the above formula (IV), R Ｐ１ is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Ｐ１ is a single bond or *-COO-. * is R Ｐ１ indicates the bonding site with the carbon atom to which L is attached. Ｐ２ and L Ｐ３ are each independently a single bond or a divalent linking group. Ｐ２ is a group in which two hydrogen atoms have been removed from a substituted or unsubstituted ring structure. Ｐ１ is 0 or 1. Ｐ２ is an integer from 1 to 3.Ｐ２ If there are two or more R Ｐ２ are the same or different, and multiple L Ｐ３ are the same or different. Ｐ３ and R Ｐ４ are each independently a hydrogen atom, a fluoro group, an alkyl group having 1 to 10 carbon atoms, or a monovalent fluorinated alkyl group having 1 to 10 carbon atoms. Ｐ３ is an integer from 0 to 10. Ｐ３ If there are two or more R Ｐ３ are the same or different, and multiple R Ｐ４ are the same or different. Ｐ５ and R Ｐ６ are each independently a fluoro group or a monovalent fluorinated alkyl group having 1 to 10 carbon atoms. Ｐ４ is an integer from 0 to 10. Ｐ３ If there are two or more R Ｐ５ are the same or different, and multiple R Ｐ６ are the same or different. － is -SO ３ － or -COO － It is. ＋ is a monovalent radiation-sensitive onium cation.

[0101] R Ｐ１ From the viewpoint of copolymerizability of the monomer that gives the structural unit (V), a hydrogen atom or a methyl group is preferred.

[0102] L Ｐ１ may be a single bond or *-COO-.

[0103] L Ｐ２ may be a single bond or a divalent linking group.

[0104] L Ｐ３ may be a single bond or a divalent linking group.

[0105] The term "linking group" refers to a group that links two or more structures. The linking group remains in the structure of a compound or polymer due to reasons such as the synthetic materials or synthetic methods, and does not affect the effects of the present invention, or has an extremely small effect on the effects of the present invention. However, this does not mean that all structures other than the linking group contribute to the exertion of the effects of the present invention.

[0106] The divalent linking group is not particularly limited as long as it is a group that links two structures, and examples thereof include a carbonyl group, an ether group, a carbonyloxy group, an amide bond, a sulfide group, a sulfonyl group, an alkanediyl group having 1 to 10 carbon atoms, or a group formed by combining these.

[0107] R Ｐ２ Examples of the ring structure having 5 or more ring members that gives the formula (I) include an aliphatic hydrocarbon ring having 5 or more ring members, an aliphatic heterocycle having 5 or more ring members, an aromatic hydrocarbon ring having 6 or more ring members, and an aromatic heterocycle having 5 or more ring members.

[0108] The "ring structure" includes an "alicyclic ring" and an "aromatic ring." The "alicyclic ring" includes an "aliphatic hydrocarbon ring" and an "aliphatic heterocyclic ring." Among alicyclic rings, polycyclic rings including an aliphatic hydrocarbon ring and an aliphatic heterocyclic ring are considered to be "aliphatic heterocyclic rings."

[0109] Examples of the aliphatic hydrocarbon ring having 5 or more ring members include monocyclic saturated alicyclic rings such as a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, a cyclooctane ring, a cyclononane ring, a cyclodecane ring, and a cyclododecane ring; monocyclic unsaturated alicyclic rings such as a cyclopentene ring, a cyclohexene ring, a cycloheptene ring, a cyclooctene ring, and a cyclodecene ring; polycyclic saturated alicyclic rings such as a norbornane ring, an adamantane ring, a tricyclodecane ring, a tetracyclododecane ring, and a steroid structure; and polycyclic unsaturated alicyclic rings such as a norbornene ring and a tricyclodecene ring. The term "steroid structure" refers to a structure having a basic skeleton (sterane skeleton) in which three six-membered rings and one five-membered ring are fused.

[0110] Examples of the aliphatic heterocyclic ring having 5 or more ring members include lactone rings such as a hexanolactone ring and a norbornanelactone ring; sultone rings such as a hexanosultone ring and a norbornanesultone ring; dioxolane ring, oxacycloheptane ring, oxanorbornane ring, 3,5-dioxatricyclo[5.2.1.0 ２，６ ] Examples of heterocyclic rings include an oxygen atom-containing heterocyclic ring such as a decane ring; a nitrogen atom-containing heterocyclic ring such as an azacyclohexane ring or a diazabicyclooctane ring; and a sulfur atom-containing heterocyclic ring such as a thiacyclohexane ring or a thianorbornane ring.

[0111] Examples of aromatic hydrocarbon rings having 6 or more ring members include the above-mentioned R Ｘ Among aromatic rings having 5 to 20 ring members which give the above formula, examples of aromatic hydrocarbon rings having 6 to 20 ring members include those exemplified above.

[0112] Examples of aromatic heterocyclic rings having 5 or more ring members include the above-mentioned R Ｘ Among aromatic rings having 5 to 20 ring members which give the above formula, examples of aromatic heterocycles having 5 to 20 ring members include those exemplified above.

[0113] The lower limit of the number of ring members in the ring structure is preferably 6, more preferably 8, still more preferably 9, and particularly preferably 10. The upper limit of the number of ring members is preferably 25.

[0114] In the ring structure, some or all of the hydrogen atoms bonded to the atoms constituting the ring structure may be substituted with a substituent. Ｘ Examples of the substituent that the group represented by the following formula may have include those exemplified above.

[0115] n Ｐ１ As the number, 1 is preferred.

[0116] n Ｐ２ As the number, 1 or 2 is preferred.

[0117] R Ｐ３ and R Ｐ４ Examples of the alkyl group having 1 to 10 carbon atoms represented by the formula (I) include a methyl group, an ethyl group, and a propyl group.

[0118] R Ｐ３ , R Ｐ４ , R Ｐ５ or RＰ６ Examples of the fluorinated alkyl group having 1 to 10 carbon atoms represented by the formula (I) include perfluoroalkyl groups such as trifluoromethyl groups.

[0119] R Ｐ３ and R Ｐ４ is preferably a hydrogen atom.

[0120] R Ｐ５ and R Ｐ６ As the group, a fluoro group or a perfluoroalkyl group is preferred, and a fluoro group or a trifluoromethyl group is more preferred.

[0121] n Ｐ３ is preferably 0 to 5, more preferably 0 to 2, and even more preferably 0 or 1.

[0122] n Ｐ３ is preferably 0 to 5, more preferably 0 to 3, and even more preferably 0 to 2.

[0123] M ＋ Examples of the monovalent radiation-sensitive onium cation represented by the formula (I) include those known as radiation-sensitive onium cations in onium salts used as radiation-sensitive acid generators or acid diffusion controllers contained in radiation-sensitive compositions. For example, sulfonium cations (S ＋ ), iodonium cation (I ＋ ) are listed.

[0124] Examples of the monovalent radiation-sensitive onium cation include monovalent cations represented by the following formulas (r-a) to (r-c) (hereinafter also referred to as "cations (r-a) to (r-c)").

[0125]

[0126] In the above formula (r-a), b1 is an integer of 0 to 4. When b1 is 1, R Ｂ１ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogeno group. Ｂ１ are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group or a halogeno group, or a plurality of R Ｂ１are combined with each other to form a ring structure having 4 to 20 ring members together with the carbon chain to which they are attached. b2 is an integer of 0 to 4. When b2 is 1, R Ｂ２ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogeno group. Ｂ２ are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group or a halogeno group, or a plurality of R Ｂ２ are combined with each other to form a ring structure having 4 to 20 ring members together with the carbon chain to which they are attached. Ｂ３ and R Ｂ４ are each independently a hydrogen atom, a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogeno group, or R Ｂ３ and R Ｂ４ are combined with each other to form a polycyclic sulfur atom-containing aromatic heterocycle together with the sulfur atom to which they are bonded. b3 is an integer of 0 to 11. When b3 is 1, R Ｂ５ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogeno group. Ｂ５ are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group or a halogeno group, or a plurality of R Ｂ５ are combined with each other to form a ring structure having 4 to 20 ring members together with the carbon chain to which they are attached. ｂ１ is an integer from 0 to 3.

[0127] In the above formula (r-b), b4 is an integer of 0 to 9. When b4 is 1, R Ｂ６ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogeno group. Ｂ６ are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group or a halogeno group, or a plurality of R Ｂ６ are combined with each other to form a ring structure having 4 to 20 ring members together with the carbon chain to which they are bonded. b5 is an integer of 0 to 10. When b5 is 1, R Ｂ７ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogeno group.Ｂ７ are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group or a halogeno group, or a plurality of R Ｂ７ are combined with each other to form a ring structure having 3 to 20 ring members together with the carbon atoms or carbon chains to which they are attached. ｂ３ is an integer from 0 to 3. Ｂ８ is a single bond or a divalent linking group. ｂ２ is an integer from 0 to 2.

[0128] In the above formula (rc), b6 is an integer of 0 to 5. When b6 is 1, R Ｂ９ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogeno group. Ｂ９ are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group or a halogeno group, or a plurality of R Ｂ９ are combined with each other to form a ring structure having 4 to 20 ring members together with the carbon chain to which they are bonded. b7 is an integer of 0 to 5. When b7 is 1, R Ｂ１０ is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogeno group. Ｂ１０ are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group or a halogeno group, or a plurality of R Ｂ１０ are combined with each other to form a ring structure having 4 to 20 ring members together with the carbon chain to which they are attached.

[0129] "Organic group" refers to a group containing at least one carbon atom.

[0130] R Ｂ１ , R Ｂ２ , R Ｂ３ , R Ｂ４ , R Ｂ５ , R Ｂ６ , R Ｂ７ , R Ｂ９ or R Ｂ１０Examples of the monovalent organic group having 1 to 20 carbon atoms and represented by the formula (I) include a monovalent hydrocarbon group having 1 to 20 carbon atoms, a group containing a divalent heteroatom-containing group between the carbon-carbon bonds of this hydrocarbon group (hereinafter also referred to as "group (β1)"), a group in which some or all of the hydrogen atoms in the hydrocarbon group or the group (β1) have been substituted with a monovalent heteroatom-containing group (hereinafter also referred to as "group (β2)"), and a group in which the hydrocarbon group, the group (β1) or the group (β2) is combined with a divalent heteroatom-containing group (hereinafter also referred to as "group (β3)").

[0131] Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include the above-mentioned R Ｙ , R Ｚ , R Ａ , or R Ｂ Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms that gives the following formula are given below.

[0132] Examples of heteroatoms constituting the monovalent or divalent heteroatom-containing group include oxygen atoms, nitrogen atoms, sulfur atoms, phosphorus atoms, silicon atoms, and halogen atoms.

[0133] Examples of the monovalent heteroatom-containing group include a halogeno group, a hydroxy group, a carboxy group, a cyano group, an amino group, a sulfanyl group (-SH), and an oxo group (=O).

[0134] Examples of the divalent heteroatom-containing group include —O—, —CO—, —S—, and —SO ２ Examples of such groups include -, -CS-, -NR'-, and groups formed by combining two or more of these groups (for example, -COO-, -CONR'-). R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. Examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by R' include those having 1 to 10 carbon atoms among the groups exemplified above as the "monovalent hydrocarbon group having 1 to 20 carbon atoms".

[0135] R Ｂ８ Examples of the divalent organic group represented by the formula (I) include those in which one hydrogen atom has been removed from the above monovalent organic group.

[0136] R Ｂ１ , R Ｂ２ , R Ｂ５ , RＢ６ , R Ｂ９ and R Ｂ１０ As the alkyl group, a perfluoroalkyl group, a fluoro group, an iodo group, a hydroxy group, an alkoxy group, an alkylsulfonyl group or a group containing an acid-dissociable group is preferred.

[0137] R Ｂ３ and R Ｂ４ is preferably a hydrogen atom or a single bond formed by combining these, and is preferably a hydrogen atom.

[0138] b1 and b2 are preferably 0 to 2, more preferably 0 or 1, and even more preferably 0. b3 is preferably 0 to 4, more preferably 0 to 2, and even more preferably 0 or 1. n ｂ１ is preferably 0 or 1.

[0139] The radiation-sensitive onium cation is preferably the cation (ra) or the cation (rc).

[0140] Examples of the cation (ra) include cations represented by the following formulas (ra-1) to (ra-19).

[0141]

[0142] Examples of the cation (r-c) include cations represented by the following formulae (r-c-1) to (r-c-4).

[0143]

[0144] Specific examples of the structure of the monomer that provides the structural unit (IVa) include the monomers (M-21) to (M-30) in the examples described below.

[0145] The lower limit of the content of the structural unit (IVa) in the polymer [A] is preferably 0.5 mol %, more preferably 1 mol %, still more preferably 2 mol %, and particularly preferably 5 mol %, based on the total structural units constituting the polymer [A]. The upper limit of the content is preferably 30 mol %, more preferably 20 mol %, and still more preferably 15 mol %.

[0146] <[Z] Compound> The [Z] compound is a compound having a sulfonate anion (hereinafter also referred to as "anion (X)") and a radiation-sensitive onium cation (hereinafter also referred to as "cation (Y)"), in which the anion (X) has an aromatic ring (hereinafter also referred to as "aromatic ring (p)") in which at least one hydrogen atom is substituted with a substituent (hereinafter also referred to as "substituent (a)"), and at least one group (hereinafter also referred to as "group (b)") selected from the group consisting of a hydroxy group and a carboxy group, in which the substituent (a) is at least one group selected from the group consisting of a fluorinated alkyl group, an unsubstituted tertiary alkyl group, and a trialkylsilyl group, and the cation (Y) has an aromatic ring (hereinafter also referred to as "aromatic ring (q)") in which at least one hydrogen atom is substituted with a fluoro group or a fluorinated alkyl group.

[0147] The compound [Z] is a substance that generates an acid when exposed to radiation. Examples of the radiation include those exemplified as radiation in the section <Method of Forming a Resist Pattern> below. The acid generated by the radiation dissociates acid-dissociable groups and generates carboxyl groups, which results in a difference in the solubility of the resist film in a developer between the exposed and unexposed areas, thereby forming a resist pattern.

[0148] Each structure of the compound (Z) will be explained below.

[0149] [Anion (X)] The anion (X) has an aromatic ring (p) in which at least one hydrogen atom is substituted with a substituent (a), and at least one group (b) selected from the group consisting of a hydroxy group and a carboxy group.

[0150] The number of aromatic rings (p) in the anion (X) is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1.

[0151] Examples of the aromatic ring that provides the aromatic ring (p) include the above-mentioned R Ｘ Examples of aromatic rings having 5 to 20 ring members that give the following formula are given below.

[0152] The aromatic ring providing the aromatic ring (p) is preferably an aromatic hydrocarbon ring having 6 to 20 ring members, and is preferably a benzene ring.

[0153] The aromatic ring (p) may have a substituent other than the substituent (a), such as a halogeno group such as a fluoro group or an iodo group, a cyano group, a nitro group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, or an acyloxy group.

[0154] The substituent (a) is at least one group selected from the group consisting of a fluorinated alkyl group, an unsubstituted tertiary alkyl group, and a trialkylsilyl group. The term "fluorinated alkyl group" refers to an alkyl group in which some or all of the hydrogen atoms have been substituted with fluoro groups.

[0155] Fluorinated alkyl groups include fluorinated primary alkyl groups, fluorinated secondary alkyl groups, and fluorinated tertiary alkyl groups.

[0156] The number of carbon atoms in the fluorinated alkyl group is preferably 1 to 20, more preferably 1 to 10, and even more preferably 1 to 5. When the fluorinated alkyl group is a fluorinated primary alkyl group, the number of carbon atoms is more preferably 1 to 3, and particularly preferably 1 or 2.

[0157] Examples of primary alkyl groups that can provide fluorinated primary alkyl groups include methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, heptyl, octyl, nonyl, and decyl groups.

[0158] Examples of secondary alkyl groups that provide fluorinated secondary alkyl groups include an isopropyl group, a sec-butyl group, and a 2-ethylhexyl group.

[0159] Examples of the tertiary alkyl group that provides the fluorinated tertiary alkyl group and the unsubstituted tertiary alkyl group include a tert-butyl group, a tert-pentyl group, and a tert-octyl group.

[0160] The number of carbon atoms in each alkyl group in the trialkylsilyl group is preferably 1 to 10, more preferably 1 to 5, and even more preferably 1 to 3.

[0161] Examples of the trialkylsilyl group include a trimethylsilyl group, a triethylsilyl group, and a triisopropylsilyl group.

[0162] The fluorinated alkyl group is preferably a perfluoroalkyl group.

[0163] The substituent (a) is preferably a fluorinated primary alkyl group, an unsubstituted tertiary alkyl group, or a trialkylsilyl group, and more preferably a trifluoromethyl group, a tert-butyl group, or a trimethylsilyl group. When the substituent (a) is a trifluoromethyl group, the LWR of the radiation-sensitive composition tends to be further improved.

[0164] The number of substituents (a) in the aromatic ring (p) is preferably 1 to 5, more preferably 1 to 3, and even more preferably 1 or 2. When the number of substituents (a) is 2 or more, the sensitivity of the radiation-sensitive composition tends to be further improved.

[0165] When the number of the substituents (a) is 2 or more and the substituents (a) are trifluoromethyl groups, the sensitivity, LWR, and resolution of the radiation-sensitive composition tend to be further improved.

[0166] The group (b) is at least one group selected from the group consisting of a hydroxy group and a carboxy group. The group (b) may be a hydroxy group or a carboxy group. When the group (b) is an alcoholic hydroxy group (i.e., not a phenolic hydroxy group), the LWR and resolution of the radiation-sensitive composition tend to be further improved. When the group (b) is a carboxy group, the LWR of the radiation-sensitive composition tends to be further improved.

[0167] The group (b) may be bonded to the aromatic ring (p) or to a site different from the aromatic ring (p).

[0168] The number of groups (b) in the anion (X) is preferably 1 to 5, more preferably 1 to 3, and even more preferably 1 or 2.

[0169] The anion (X) preferably further has a ring structure other than the aromatic ring (p). Examples of the other ring structure include the above-mentioned R Ｐ２ Examples of ring structures having 5 or more ring members that give the following formula are given below.

[0170] [Cation (Y)] The cation (Y) is a radiation-sensitive onium cation having an aromatic ring (q) in which at least one hydrogen atom is substituted with a fluoro group or a fluorinated alkyl group.

[0171] The number of aromatic rings (q) in the cation (Y) is preferably 1 to 3.

[0172] Examples of the aromatic ring that provides the aromatic ring (q) include the above-mentioned R Ｘ Examples of aromatic rings having 5 to 20 ring members that give the following formula are given below.

[0173] The aromatic ring that provides the aromatic ring (q) is preferably an aromatic hydrocarbon ring having 6 to 20 ring members, and is preferably a benzene ring.

[0174] Examples of the fluorinated alkyl group contained in the aromatic ring (q) include those exemplified above as the fluorinated alkyl group contained in the aromatic ring (p).

[0175] The fluorinated alkyl group contained in the aromatic ring (q) is preferably a perfluoroalkyl group, more preferably a trifluoromethyl group.

[0176] The aromatic ring (q) may have a substituent other than a fluoro group or a fluorinated alkyl group, such as a halogeno group (e.g., an iodo group), a cyano group, a nitro group, an alkoxycarbonyl group, an alkoxycarbonyloxy group, an acyl group, an acyloxy group, or an alkylsulfonyl group.

[0177] Examples of the cation (X) include those having a fluoro group or a fluorinated alkyl group among the above-mentioned cations (r-a) to (r-c). More specifically, the cation (X) is a cation represented by the above formula (r-a) in which b1 + b2 + b3 is 1 or more and R Ｂ１ , R Ｂ２ and R Ｂ３wherein at least one of the groups is a fluoro group or a fluorinated alkyl group; and in the above formula (r-b), b4 is 1 or more, and R ６ is a fluoro group or a fluorinated alkyl group, in the above formula (r-c), b6+b7 is 1 or more, and R Ｂ９ and R Ｂ１０ At least one of the groups is a fluoro group or a fluorinated alkyl group.

[0178] Specific examples of the cation (X) include the cations represented by the above formulae (r-a-6) to (r-a-16), (r-a-18) and (r-a-19), and the cations represented by the above formula (r-c-2) or (r-c-4).

[0179] The compound [Z] may be a compound represented by the following formula (1).

[0180]

[0181] In the above formula (1), Ar １ is a substituted or unsubstituted aromatic ring (n １ +n ２ +1) hydrogen atoms are removed. １ is a fluorinated alkyl group, an unsubstituted tertiary alkyl group, or a trialkylsilyl group. １ is an integer from 1 to 5. １ If there are two or more R １ are the same or different. ２ and R ３ are each independently a hydroxy group or a carboxy group. ２ is a divalent organic group. ２ is an integer from 0 to 5. ３ is an integer from 0 to 5. ２ +n ３ is an integer of 1 or more. ２ If there are two or more R ２ are the same or different, and multiple L ２ are the same or different. ３ If is 2 or more, R ３ are the same or different. １ is (n ３+2)valent organic group. ４ and R ５ are each independently a hydrogen atom, a fluoro group, an alkyl group or a fluorinated alkyl group. ４ is an integer from 0 to 10. ４ If there are two or more R ４ are the same or different, and multiple R ５ are the same or different. ６ and R ７ are each independently a fluoro group or a fluorinated alkyl group. ５ is an integer from 1 to 10. ５ If there are two or more R ６ are the same or different, and multiple R ７ are the same or different. ＋ is the radiation-sensitive onium cation.

[0182] Ar １ The aromatic ring giving the formula (I) is described above as the aromatic ring (p).

[0183] R １ The fluorinated alkyl groups, unsubstituted tertiary alkyl groups and trialkylsilyl groups which give the following are described above as the substituent (a).

[0184] R １ As the alkyl group, a trifluoromethyl group is preferred. In this case, the LWR of the radiation-sensitive composition tends to be further improved.

[0185] n １ is preferably 1 to 3, and more preferably 1 or 2. １ When is 2 or more, the sensitivity of the radiation-sensitive composition tends to be further improved.

[0186] n １ is 2 or more, and R １ When is a trifluoromethyl group, the sensitivity, LWR, and resolution of the radiation-sensitive composition tend to be further improved.

[0187] R ２ and R ３ The hydroxy or carboxy group giving the formula (I) is described above as group (b).

[0188] L １ and L ２ Examples of the organic group that gives the above-mentioned R Ｂ１ , R Ｂ２ , R Ｂ３ , R Ｂ４ , R Ｂ５ , R Ｂ６ , R Ｂ７ , R Ｂ９ or R Ｂ１０ Examples of the monovalent organic group having 1 to 20 carbon atoms represented by the following formula (I) include groups in which the corresponding number of hydrogen atoms have been removed from the examples of the monovalent organic group having 1 to 20 carbon atoms represented by the following formula (I).

[0189] L １ and L ２ The organic group that provides the formula (I) preferably contains a ring structure. The ring structure is explained as a ring structure other than the above-mentioned aromatic ring (p).

[0190] n ２ +n ３ As the number, 1 to 5 is preferred, 1 to 3 is more preferred, and 1 or 2 is even more preferred.

[0191] n ２ When is 1 or more, the LWR of the radiation-sensitive composition tends to be further improved.

[0192] n ３ is 1 or more, and R ３ When is a carboxy group, the LWR of the radiation-sensitive composition tends to be further improved.

[0193] n ３ is 1 or more, and R ３ When R is a hydroxy group, the LWR and resolution of the radiation-sensitive composition tend to be further improved. ３ This tendency is stronger when is an alcoholic hydroxy group.

[0194] R ４ Examples of the alkyl group that gives Ｐ３ and R Ｐ４ Examples of the alkyl group having 1 to 10 carbon atoms represented by the following formula are given below.

[0195] R ４ or R ５Examples of the fluorinated alkyl group that gives the formula Ｐ３ , R Ｐ４ , R Ｐ５ or R Ｐ６ Examples of the fluorinated alkyl group having 1 to 10 carbon atoms represented by the following formula are given below.

[0196] n ４ is preferably 0 to 5, more preferably 0 to 3, and even more preferably 0 or 1.

[0197] n ５ is preferably 1 to 5, more preferably 1 to 3, and even more preferably 1 or 2. ５ When is 2 or more, the LWR and resolution of the radiation-sensitive composition tend to be further improved.

[0198] M ＋ The radiation-sensitive onium cation represented by the formula (I) is explained above as the cation (Y).

[0199] The compound [Z] is preferably a compound represented by the following formulas (1-1) to (1-4).

[0200]

[0201] In the above formulas (1-1) to (1-4), Ar １ , R １ , n １ , R ２ , n ２ , R ４ , R ５ , n ４ , R ６ , R ７ , n ５ and M ＋ has the same meaning as in formula (1). ８ is a hydroxy group or a carboxy group. ６ is an integer from 1 to 5. ６ If there are two or more R ８ are the same or different. ２ is a substituted or unsubstituted aromatic ring (n ６ +1) hydrogen atoms are removed. ３ and L ４ is a divalent linking group. ９R is a trivalent chain hydrocarbon group or a group in which three hydrogen atoms have been removed from a ring structure. １０ is a group in which three hydrogen atoms have been removed from a ring structure. １１ is a divalent chain hydrocarbon group. １２ is a group in which two hydrogen atoms have been removed from a ring structure.

[0202] Ar ２ The aromatic ring that gives １ This is similar to the aromatic ring that gives

[0203] L ３ and L ４ Examples of the divalent linking group that gives Ｐ３ Examples of the divalent linking group that gives the following include those exemplified above.

[0204] R ９ and R １１ Examples of the chain hydrocarbon group that gives the above-mentioned R Ｘ Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms which gives the following formula include those obtained by removing the corresponding number of hydrogen atoms from the examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms which gives the formula:

[0205] R ９ , R １０ and R １２ Examples of the ring structure that gives Ｐ２ Examples of ring structures having 5 or more ring members that give the following formula are given below.

[0206] Examples of the compound [Z] include compounds represented by the following formulas (1-1-1), (1-2-1) to (1-2-4), (1-3-1) to (1-3-2), and (1-4-1).

[0207]

[0208] In the above formulas (1-1-1), (1-2-1) to (1-2-4), (1-3-1) to (1-3-2), and (1-4-1), M ＋ is synonymous with the above formula (1).

[0209] Specific structures of the compound [Z] include, for example, compounds (Z-1) to (Z-8) in the examples described later.

[0210] Compound [Z] can be synthesized by known methods, such as those described in Synthesis Examples 3-1 to 3-8 in the Examples below.

[0211] The lower limit of the amount of the compound [Z] in the radiation-sensitive composition is preferably 5 parts by mass and more preferably 10 parts by mass, relative to 100 parts by mass of the polymer [A].The upper limit of the amount is preferably 100 parts by mass and more preferably 90 parts by mass.

[0212] <Acid Diffusion Controller (C)> The acid diffusion controller (C) controls the diffusion phenomenon in the resist film of the acid generated from the compound (Z) or the like upon exposure, and thereby controls undesirable chemical reactions in the unexposed areas. The radiation-sensitive composition may contain one or more acid diffusion controllers (C).

[0213] Examples of the acid diffusion controller (C) include nitrogen atom-containing compounds and compounds having a radiation-sensitive onium cation and an organic acid anion (hereinafter also referred to as "photodegradable bases").

[0214] Examples of the nitrogen atom-containing compound include amine compounds such as tripentylamine and trioctylamine; amide group-containing compounds such as formamide and N,N-dimethylacetamide; urea compounds such as urea and 1,1-dimethylurea; and nitrogen-containing heterocyclic compounds such as pyridine, N-(undecylcarbonyloxyethyl)morpholine, and N-t-pentyloxycarbonyl-4-hydroxypiperidine.

[0215] The photodegradable base generates a weak acid in the exposed area to increase the solubility or insolubility of the polymer (A) in a developer, thereby suppressing the surface roughness of the exposed area after development. On the other hand, in the unexposed area, the anion exerts a high acid-scavenging function and functions as a quencher, capturing acid diffusing from the exposed area.

[0216] Examples of the radiation-sensitive onium cation in the photodegradable base include the radiation-sensitive onium cations described above in the section <[F] Polymer>.

[0217] The organic acid anion in the photodegradable base is not particularly limited as long as it is usable as an organic acid anion in a photodegradable base, and examples thereof include carboxylate anions.

[0218] As the photodegradable base, a compound in which the above-mentioned radiation-sensitive onium cation and the above-mentioned anion are appropriately combined can be used.

[0219] Specific examples of the structure of the acid diffusion controller [C] include the acid diffusion controllers (C-1) to (C-11) in the examples described later.

[0220] When the radiation-sensitive composition contains the acid diffusion controller (C), the lower limit of the content of the acid diffusion controller (C) in the radiation-sensitive composition is preferably 5 mol %, more preferably 10 mol %, and even more preferably 15 mol %, relative to 100 mol % of the radiation-sensitive acid generator (or the total amount of the radiation-sensitive acid generators, if multiple radiation-sensitive acid generators are present). The upper limit of the content is preferably 100 mol %, more preferably 70 mol %, and even more preferably 60 mol %.

[0221] <Compound [D]> The compound [D] is a compound containing a carboxy group. By including the compound [D], the radiation-sensitive composition can have improved solubility, and as a result, improved resolution. Examples of the compound [D] include saturated aliphatic carboxylic acids, unsaturated aliphatic carboxylic acids, alkoxycarboxylic acids, ketocarboxylic acids, and aromatic carboxylic acids.

[0222] Examples of saturated aliphatic carboxylic acids include monovalent saturated aliphatic carboxylic acids such as formic acid, acetic acid, propionic acid, n-butanoic acid, 2-methylpropionic acid, pentanoic acid, hexanoic acid, and heptanoic acid; and polyvalent saturated aliphatic carboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, and suberic acid.

[0223] Examples of unsaturated aliphatic carboxylic acids include monovalent unsaturated aliphatic carboxylic acids such as (meth)acrylic acid, crotonic acid, isocrotonic acid, 3-butenoic acid, 4-pentenoic acid, and 2-butynoic acid; and polyvalent unsaturated aliphatic carboxylic acids such as maleic acid and fumaric acid.

[0224] Examples of the alkoxycarboxylic acid include methoxyacetic acid.

[0225] Examples of ketocarboxylic acids include pyruvic acid and benzoylformic acid.

[0226] Examples of aromatic carboxylic acids include monovalent aromatic carboxylic acids such as benzoic acid, p-hydroxybenzoic acid, and salicylic acid; and polyvalent aromatic carboxylic acids such as phthalic acid, terephthalic acid, and isophthalic acid.

[0227] The compound [D] is preferably an aromatic carboxylic acid, and more preferably a compound containing a salicylic acid structure, such as salicylic acid, 4-methylsalicylic acid, 3,4-dimethylsalicylic acid, 5-ethylsalicylic acid, 6-methoxysalicylic acid, 2,6-dihydroxybenzoic acid, 2,6-dihydroxy-4-methylbenzoic acid, and 2,4-dihydroxy-6-methylbenzoic acid.

[0228] Compound (D) is preferably a compound containing an iodo group, more preferably an aromatic carboxylic acid containing an iodo group, and even more preferably a compound containing an iodo group and a salicylic acid structure.

[0229] Examples of the compound containing an iodo group include aliphatic carboxylic acids containing an iodo group, such as iodoacetic acid, 3-iodopropionic acid, fluoroiodoacetic acid, and 4-iodobutanoic acid, and aromatic carboxylic acids containing an iodo group, such as 2,3,5-triiodobenzoic acid and 3,5-diiodo-4-methoxybenzoic acid.

[0230] An example of a compound containing an iodo group and a salicylic acid structure is 3,5-diiodosalicylic acid.

[0231] The lower limit of the amount of the compound [D] in the radiation-sensitive composition is preferably 0.01 parts by mass, more preferably 0.1 parts by mass, and even more preferably 1 part by mass, relative to 100 parts by mass of the polymer [A].The upper limit of the amount is preferably 30 parts by mass, more preferably 20 parts by mass, and even more preferably 10 parts by mass.

[0232] <[E] Organic Solvent> The radiation-sensitive composition usually contains an organic solvent [E]. The organic solvent [E] is not particularly limited as long as it is a solvent that can dissolve or disperse at least the polymer [A], the compound [Z], the acid diffusion controller [C], the compound [D], the polymer [F], and other optional components that may be contained as needed.

[0233] Examples of the organic solvent (E) include alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, and hydrocarbon solvents. The radiation-sensitive composition may contain one or more organic solvents (E).

[0234] Examples of alcohol-based solvents include aliphatic monoalcohol-based solvents such as 4-methyl-2-pentanol, n-hexanol, diacetone alcohol, and methyl 2-hydroxyisobutyrate; alicyclic monoalcohol-based solvents such as cyclohexanol; polyhydric alcohol-based solvents such as 1,2-propylene glycol; and polyhydric alcohol partial ether-based solvents such as propylene glycol monomethyl ether.

[0235] Examples of ether solvents include dialkyl ether solvents such as diethyl ether, dipropyl ether, dibutyl ether, dipentyl ether, diisoamyl ether, dihexyl ether, and diheptyl ether; cyclic ether solvents such as tetrahydrofuran and tetrahydropyran; and aromatic ring-containing ether solvents such as diphenyl ether and anisole.

[0236] Examples of ketone solvents include chain ketone solvents such as acetone, methyl ethyl ketone, methyl n-propyl ketone, methyl n-butyl ketone, diethyl ketone, methyl isobutyl ketone, 2-heptanone, ethyl n-butyl ketone, methyl n-hexyl ketone, di-isobutyl ketone, and trimethylnonanone; cyclic ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, and methylcyclohexanone; 2,4-pentanedione, acetonylacetone, and acetophenone.

[0237] 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.

[0238] Examples of ester-based solvents include monocarboxylic acid ester-based solvents such as n-butyl acetate and ethyl lactate; lactone-based solvents such as γ-butyrolactone and valerolactone; polyhydric alcohol carboxylate-based solvents such as propylene glycol acetate; polyhydric alcohol partial ether carboxylate-based solvents such as propylene glycol monomethyl ether acetate; polycarboxylic acid diester-based solvents such as diethyl oxalate; and carbonate-based solvents such as dimethyl carbonate and diethyl carbonate.

[0239] Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents such as n-pentane and n-hexane; and aromatic hydrocarbon solvents such as toluene and xylene.

[0240] The organic solvent (E) is preferably an alcohol solvent, an ester solvent, or a combination thereof, more preferably an aliphatic monoalcohol solvent, a polyhydric alcohol partial ether solvent, a polyhydric alcohol partial ether carboxylate solvent, or a combination thereof, and even more preferably diacetone alcohol, methyl 2-hydroxyisobutyrate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, or a combination thereof.

[0241] When the radiation-sensitive composition contains the organic solvent (E), the lower limit of the content of the organic solvent (E) is preferably 50 mass %, more preferably 60 mass %, still more preferably 70 mass %, and particularly preferably 80 mass %, based on all components contained in the radiation-sensitive composition, and the upper limit of the content is preferably 99.9 mass %, preferably 99.5 mass %, and more preferably 99.0 mass %.

[0242] <Polymer [F]> The polymer [F] is a polymer different from the polymer [A] and has a higher fluorine atom content than the polymer [A]. Typically, polymers that are more hydrophobic than the base polymer tend to be unevenly distributed in the surface layer of the resist film. The polymer [F] has a higher fluorine atom content than the polymer [A], and due to this hydrophobicity-induced property, the polymer [F] tends to be unevenly distributed in the surface layer of the resist film. As a result, when the radiation-sensitive composition contains the polymer [F], it is expected that the cross-sectional shape of the formed resist pattern will be excellent.

[0243] The form in which fluorine atoms are contained in the polymer [F] is not particularly limited, and they may be bonded to either the main chain or the side chain of the polymer [F]. Regarding the form in which fluorine atoms are contained in the polymer [F], it is preferable that the polymer [F] has a structural unit containing a fluorine atom (hereinafter also referred to as "structural unit (If)"). Specific examples of monomers that provide the structural unit (If) include, for example, monomers (FM-1) to (FM-10) in the examples described later.

[0244] The polymer [F] may further have a structural unit other than the structural unit (F). Examples of structural units other than the structural unit (F) include the structural unit (Ia) containing an acid-dissociable group and the structural unit (IIIa) containing a polar group, which are described above in the section <Polymer [A]>. The polymer [F] may have one or more types of each structural unit.

[0245] When the radiation-sensitive composition contains the polymer [F], the lower limit of the amount of the polymer [F] relative to 100 parts by mass of the polymer [A] is preferably 0.1 parts by mass and more preferably 0.5 parts by mass, and the upper limit of the amount is preferably 20 parts by mass and more preferably 10 parts by mass.

[0246] <Other Optional Components> Examples of other optional components include a radiation-sensitive acid generator other than the compound [Z] and a surfactant. The radiation-sensitive composition may contain one or more other optional components.

[0247] <Method of Forming a Resist Pattern> The method of forming a resist pattern includes a step of applying a radiation-sensitive composition directly or indirectly to a substrate (hereinafter also referred to as a "coating step"), a step of exposing the resist film formed in the coating step (hereinafter also referred to as an "exposure step"), and a step of developing the exposed resist film (hereinafter also referred to as a "developing step").

[0248] In the coating step, the radiation-sensitive composition is the radiation-sensitive composition described above. Therefore, according to the method for forming a resist pattern, a resist pattern with excellent sensitivity, LWR, and resolution can be formed.

[0249] Each step of the resist pattern forming method will be described below.

[0250] [Coating Step] In this step, the radiation-sensitive composition is coated directly or indirectly onto a substrate, thereby forming a resist film directly or indirectly on the substrate.

[0251] In this step, the radiation-sensitive composition described above is used as the radiation-sensitive composition.

[0252] Substrates include, for example, silicon wafers, silicon dioxide, and aluminum coated wafers.

[0253] Examples of coating methods include spin coating, casting coating, and roll coating. After coating, if necessary, pre-baking (hereinafter also referred to as "PB") may be performed to volatilize the solvent in the coating film. The PB temperature and PB time are not particularly limited, and are, for example, performed at a temperature of 60°C to 150°C for 5 seconds to 300 seconds. The average thickness of the formed resist film is not particularly limited, and is, for example, 10 nm to 1,000 nm.

[0254] [Exposure Step] In this step, the resist film formed in the coating step is exposed to radiation. This exposure is carried out by irradiating the resist film through a photomask (or, in some cases, through an immersion medium such as water) with radiation. The radiation can be appropriately selected depending on the line width, diameter, etc. of the desired pattern, and examples thereof include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light (EUV), X-rays, and gamma rays; and charged particle beams such as electron beams and alpha rays. Among these, far ultraviolet light, EUV, or electron beams are preferred, with ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), EUV (wavelength 13.5 nm), or electron beams being more preferred, and KrF excimer laser light, EUV, or electron beams being even more preferred, with EUV or electron beams being particularly preferred.

[0255] After the exposure, it is preferable to perform post-exposure baking (hereinafter also referred to as "PEB"). This PEB can increase the difference in solubility in a developer between the exposed and unexposed areas. The PEB temperature and PEB time are not particularly limited, and can be performed, for example, at a temperature of 50°C to 180°C for 5 to 600 seconds.

[0256] [Development Step] In this step, the exposed resist film is developed. This allows a predetermined resist pattern to be formed. The development method in the development step may be alkali development or organic solvent development.

[0257] In the case of alkaline development, examples of the developer used for development include alkaline aqueous solutions 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 (hereinafter also referred to as "TMAH"), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, and 1,5-diazabicyclo-[4.3.0]-5-nonene. Among these, aqueous TMAH solutions are preferred, and 2.38% by mass aqueous TMAH solutions are more preferred.

[0258] In the case of organic solvent development, examples of the developer include the organic solvents exemplified above as the organic solvent (E) of the radiation-sensitive composition.

[0259] <Compound> The compound is described above as the compound [Z]. The compound can be suitably used as a radiation-sensitive acid generator in a radiation-sensitive composition.

[0260] Specific structures of the compounds include, for example, compounds (Z-1) to (Z-7) in the examples described below.

[0261] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0262] <Synthesis of Polymer [A]> [Synthesis Examples 1-1 to 1-33] Synthesis of Polymers (A-1) to (A-33) Monomers were combined according to the compositions shown in Table 1 below, and copolymerization was carried out in tetrahydrofuran (THF). The resulting polymers were crystallized in methanol, repeatedly washed with hexane, and then isolated and dried to obtain Polymers (A-1) to (A-33). Compounds represented by the following formulas (M-1) to (M-34) (hereinafter also referred to as "Monomers (M-1) to (M-34)") were used to synthesize Polymer [A]. The Mw and Mw / Mn of the resulting Polymer [A] were confirmed by GPC as described above in the section [Method for Measuring Mw and Mn].

[0263]

[0264]

[0265]

[0266] The types and contents of the monomers that provide each structural unit of the polymers obtained in Synthesis Examples 1-1 to 1-33, as well as Mw and Mw / Mn, are shown in the following Table 1. In the following Table 1, "-" indicates that the corresponding monomer was not used.

[0267]

[0268] <Synthesis of Polymer [F]> [Synthesis Examples 2-1 to 2-19] Synthesis of Polymers (F-1) to (F-19) Monomers were combined in the compositions shown in Table 2 below and copolymerized in THF. After polymerization, the solvent was replaced with acetonitrile and the mixture was washed with hexane. The solvent was then replaced with propylene glycol monomethyl ether acetate to obtain Polymers (F-1) to (F-19). The synthesis of Polymer [F] used the above-mentioned monomers (M-7), (M-9), and (M-31) to (M-34), as well as compounds represented by the following formulae (FM-1) to (FM-10) and (M-35) (hereinafter also referred to as "Monomers (FM-1) to (FM-10) and (M-35)"). The Mw and Mw / Mn of the obtained Polymer [F] were confirmed by GPC as described above in the section [Method for Measuring Mw and Mn].

[0269]

[0270] The types and contents of the monomers that provide each structural unit of the polymers obtained in Synthesis Examples 2-1 to 2-19, as well as Mw and Mw / Mn, are shown in Table 2. In Table 2, "-" indicates that the corresponding monomer was not used.

[0271]

[0272] <Synthesis of Compound [Z]> Compounds represented by the following formulae (Z-1) to (Z-8) (hereinafter also referred to as "compounds (Z-1) to (Z-8)") were synthesized according to the following method.

[0273]

[0274] Synthesis Example 3-1 Synthesis of Compound (Z-1) Compound (Z-1) was synthesized according to the following reaction scheme.

[0275]

[0276] 50 mmol of anthracene, 50 mmol of succinic anhydride, and 50 ml of xylene were added to a reaction vessel, and the mixture was heated to reflux at 140° C. for 12 hours. After the reaction was completed, the mixture was cooled to 0° C., and the precipitated solid was filtered and dried to obtain a compound represented by the above formula (ppZ-1) (hereinafter also referred to as "compound (ppZ-1)").

[0277] 40 mmol of compound (ppZ-1), 40 mmol of N,N,N-trimethyl-1-phenylmethaneammonium 1,1-difluoro-2-((2-hydroxy-4-(trifluoromethyl)benzoyl)oxy)ethane-1-sulfonate, and 80 ml of acetonitrile were added to a reaction vessel and cooled to 0°C. Next, 42 mmol of sodium hydride was added, and the mixture was stirred at room temperature for 12 hours. After completion of the reaction, the mixture was diluted with ethyl acetate and washed twice with 2 M hydrochloric acid and twice with ultrapure water. The solvent was distilled off, and the residue was purified by silica gel column chromatography to obtain a compound represented by the above formula (pZ-1) (hereinafter also referred to as "compound (pZ-1)").

[0278] 20 mmol of compound (pZ-1), 20 mmol of bis(3,5-difluorophenyl)(phenyl)sulfonium chloride, 40 ml of dichloromethane, and 40 ml of ultrapure water were added to a reaction vessel and vigorously stirred at room temperature for 3 hours. Next, the organic layer was washed three times with ultrapure water, and the solvent was distilled off to obtain compound (Z-1).

[0279] Synthesis Example 3-2 Synthesis of Compound (Z-2) Compound (Z-2) was synthesized according to the following reaction scheme.

[0280]

[0281] 55 mmol of magnesium and 10 ml of tetrahydrofuran were added to a reaction vessel, and while maintaining the temperature at room temperature, 50 ml of a 1 M solution of 5-bromo-2,2-dimethyl-1,3-benzodioxole in tetrahydrofuran was added dropwise, followed by stirring for 2 hours. Next, 50 ml of a 1 M solution of 3,5-bis(trifluoromethyl)benzaldehyde in tetrahydrofuran was added dropwise, followed by stirring for 2 hours. The reaction was quenched with 2 M hydrochloric acid, and the mixture was extracted with ethyl acetate. The organic layer was washed twice with ultrapure water, and the solvent was distilled off. The resulting residue was dissolved in 100 ml of dichloromethane, 10 ml of trifluoroacetic acid was added, and the mixture was stirred for 24 hours. After washing twice with ultrapure water, the solvent was distilled off, and the mixture was purified by silica gel column chromatography to obtain a compound represented by the above formula (pZ-2) (hereinafter also referred to as "compound (pZ-2)").

[0282] 30 mmol of compound (pZ-2), 30 mmol of (4-fluorophenyl)bis(4-(trifluoromethyl)phenyl)sulfonium carboxydifluoromethanesulfonate, 3 mmol of 4-dimethylaminopyridine, and 50 ml of dichloromethane were added to a reaction vessel and cooled to 0°C. Next, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride was added, and the mixture was stirred at room temperature for 4 hours. The reaction was quenched with 2 M hydrochloric acid, and the organic layer was washed twice with ultrapure water. The solvent was distilled off, and the resulting residue was purified by silica gel column chromatography to obtain compound (Z-2).

[0283] Synthesis Examples 3-3 and 3-4: Synthesis of Compounds (Z-3) and (Z-4) Compounds (Z-3) and (Z-4) were synthesized in the same manner as in Synthesis Example 3-2, except that the substrates used were appropriately selected.

[0284] Synthesis Example 3-5 Synthesis of Compound (Z-5) Compound (Z-5) was synthesized according to the following reaction scheme.

[0285]

[0286] 50 mmol of 3,5-bis(trifluoromethyl)phenol, 50 mmol of methyl 5-bromo-4-oxopentanoate, 50 mmol of potassium iodide, 50 mmol of potassium carbonate, and 200 ml of acetone were added to a reaction vessel and stirred at room temperature for 12 hours. The solvent was distilled off, and 200 ml of 2 M aqueous sodium hydroxide solution was added, followed by stirring for 24 hours. 400 ml of 2 M hydrochloric acid was added, and the mixture was extracted with dichloromethane. The solvent was distilled off, and the residue was purified by silica gel column chromatography to obtain a compound represented by the above formula (pZ-5) (hereinafter also referred to as "compound (pZ-5)").

[0287] 20 mmol of compound (pZ-5), 20 mmol of (4-methoxy-3-(methylsulfonyl)phenyl)bis(4-(trifluoromethyl)phenyl)sulfonium 2-(5,6-dihydroxybicyclo[2.2.1]heptan-2-yl)-1,1,2,2-tetrafluoroethane-1-sulfonate, 2 mmol of sulfuric acid, and 100 ml of toluene were added to a reaction vessel, and the mixture was heated and stirred at 140°C for 12 hours. The mixture was diluted with dichloromethane and washed three times with ultrapure water. The solvent was distilled off, and the mixture was purified by silica gel column chromatography to obtain compound (Z-5).

[0288] Synthesis Examples 3-6 and 3-8: Synthesis of Compounds (Z-6) to (Z-8) Compounds (Z-6) to (Z-8) were synthesized in the same manner as in Synthesis Example 3-5, except that the substrates used were appropriately selected.

[0289] <Preparation of Radiation-Sensitive Composition> The components used in preparing the radiation-sensitive composition are shown below. In the following examples and comparative examples, unless otherwise specified, "parts by mass" means a value when the mass of the polymer [A] used is taken as 100 parts by mass.

[0290] [Polymer (A)] As the polymer (A), polymers (A-1) to (A-33) were used.

[0291] [[B] Acid Generator] As the acid generator [B], compounds (Z-1) to (Z-8) and compounds represented by the following formulas (B-1) to (B-9) (hereinafter also referred to as "compounds (B-1) to (B-9)") were used. Note that compounds (B-1) to (B-9) are control compounds that do not correspond to the above-mentioned [Z] compounds.

[0292]

[0293] [[C] Acid Diffusion Controller] As the acid diffusion controller [C], compounds represented by the following formulas (C-1) to (C-11) (hereinafter also referred to as "acid diffusion controllers (C-1) to (C-11)") were used.

[0294]

[0295] [Compound [D]] As the compound [D], compounds represented by the following formulas (D-1) to (D-9) (hereinafter also referred to as "compounds (D-1) to (D-9)") were used.

[0296]

[0297] [[E] Organic Solvent] The following organic solvents were used as the organic solvent [E]: (E-1): Propylene glycol monomethyl ether acetate (E-2): Propylene glycol monomethyl ether (E-3): Diacetone alcohol (E-4): Methyl 2-hydroxyisobutyrate

[0298] [Polymer (F)] Polymers (F-1) to (F-19) were used as the polymer (F).

[0299] Example 1 Preparation of Radiation-Sensitive Composition (R-1) 100 parts by mass of polymer (A-1), 30 parts by mass of compound (Z-1), 30 mol% of acid diffusion controller (C-1) relative to compound (Z-1), 5 parts by mass of polymer (F-1), 2,000 parts by mass of organic solvent (E-1), and 4,800 parts by mass of organic solvent (E-2) were mixed. The resulting mixture was filtered through a membrane filter with a pore size of 0.20 μm to prepare radiation-sensitive composition (R-1).

[0300] Examples 2 to 69 and Comparative Examples 1 to 11 Preparation of Radiation-Sensitive Compositions (R-2) to (R-98) and (CR-1) to (CR-11) Radiation-sensitive compositions (R-2) to (R-69) and (CR-1) to (CR-11) were prepared in the same manner as in Example 1, except that the types and amounts of each component shown in Tables 3 to 5 below were used.

[0301] In Tables 3 to 5 below, "-" indicates that the corresponding component was not used. In Tables 3 to 5 below, the content of the acid diffusion controller [C] refers to the molar ratio relative to the radiation-sensitive acid generator (total of the radiation-sensitive acid generators if multiple radiation-sensitive acid generators are present). For example, the content of the acid diffusion controller (C-1) in Example 15 means that it was 30 mol % relative to the total of the compound (Z-1) and the structural units derived from the monomer (M-21) in the polymer (A-15). Examples 16 to 24 were similar to Example 15.

[0302]

[0303]

[0304]

[0305] <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 50-nm-thick underlayer film (AL412 (manufactured by Brewer Science)) had been formed, using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"). After PB at 130°C for 60 seconds, the wafer was cooled at 23°C for 30 seconds to form a 50-nm-thick resist film. Next, this resist film was irradiated with EUV using an EUV exposure machine (ASML's "NXE3300", NA = 0.33, illumination conditions: Conventional s = 0.89, mask: imecDEFECT32FFR02). The resist film was subjected to PEB at 110°C for 60 seconds. The resist was then developed with a 2.38% by mass aqueous solution of TMAH at 23° C. for 30 seconds to form a positive 32 nm line and space pattern.

[0306] <Evaluation> The sensitivity, LWR and resolution were evaluated according to the following methods. The results are shown in Tables 6 to 8 below.

[0307] [Sensitivity] The exposure dose at which the resist pattern was formed in the above section <Formation of Resist Pattern> was taken as the optimum exposure dose, and this value was used to determine the sensitivity (unit: mJ / cm ２ The sensitivity was 40 mJ / cm ２ If it is less than 40 mJ / cm, it is rated as "A" (good). ２ 45mJ / cm or more ２If it is less than 45 mJ / cm, it is rated as "B" (fairly good). ２ In the above cases, the evaluation was "C" (poor).

[0308] [LWR] The resist pattern formed in the above section <Formation of Resist Pattern> was observed from above the pattern using a scanning electron microscope (Hitachi High-Tech Corporation's "CG-4100"). Line widths were measured at a total of 50 arbitrary points. A 3 sigma value was determined from the distribution of the measured values, and the determined 3 sigma value was taken as the LWR (unit: nm). The smaller the LWR value, the better the result. LWR was evaluated as "A" (good) when it was less than 2.6 nm, "B" (fairly good) when it was 2.6 nm or more but less than 2.8 nm, and "C" (poor) when it was 2.8 nm or more.

[0309] [Resolution] The resist pattern formed in the above section <Formation of Resist Pattern> was observed from above the pattern using the above scanning electron microscope. In the above pattern, the minimum value of the width of the space pattern that can be resolved without bridge defects or residue defects was defined as the minimum CD (Critical Dimension) (unit: nm). The smaller the minimum CD, the better the resolution can be evaluated. The resolution was evaluated as "A" (good) when the minimum CD value was less than 12.5 nm, "B" (fairly good) when it was 12.5 nm or more but less than 13.0 nm, and "C" (poor) when it was 13.0 nm or more.

[0310]

[0311]

[0312]

[0313] The results in Tables 6 to 8 show that the radiation-sensitive compositions of the Examples all had better sensitivity, LWR and resolution than the radiation-sensitive compositions of the Comparative Examples.

Claims

1. A radiation-sensitive composition comprising: a polymer whose solubility in a developer changes under the action of an acid; and a compound having a sulfonate anion and a radiation-sensitive onium cation, wherein the sulfonate anion has an aromatic ring in which at least one hydrogen atom is substituted with a substituent, and at least one group selected from the group consisting of a hydroxy group and a carboxy group, the substituent being at least one group selected from the group consisting of a fluorinated alkyl group, an unsubstituted tertiary alkyl group, and a trialkylsilyl group, and the radiation-sensitive onium cation has an aromatic ring in which at least one hydrogen atom is substituted with a fluoro group or a fluorinated alkyl group.

2. The radiation-sensitive composition according to claim 1, wherein the fluorinated alkyl group of the sulfonate anion is a perfluoroalkyl group.

3. A radiation-sensitive composition wherein the compound is represented by the following formula (1): (In formula (1), Ar １ is a substituted or unsubstituted aromatic ring (n １ +n ２ +1) hydrogen atoms are removed. １ is a fluorinated alkyl group, an unsubstituted tertiary alkyl group, or a trialkylsilyl group. １ is an integer from 1 to 5. １ If there are two or more R １ are the same or different. ２ and R ３ are each independently a hydroxy group or a carboxy group. ２ is a divalent organic group. ２ is an integer from 0 to 5. ３ is an integer from 0 to 5. ２ +n ３ is an integer of 1 or more. ２ If there are two or more R ２ are the same or different, and multiple L ２ are the same or different. ３ If is 2 or more, R ３ are the same or different. １ is (n ３ +2)valent organic group. ４ and R ５ are each independently a hydrogen atom, a fluoro group, an alkyl group or a fluorinated alkyl group. ４ is an integer from 0 to 10. ４ If there are two or more R ４ are the same or different, and multiple R ５ are the same or different. ６ and R ７ are each independently a fluoro group or a fluorinated alkyl group. ５ is an integer from 1 to 10. ５ If there are two or more R ６ are the same or different, and multiple R ７ are the same or different. ＋ is the above-mentioned radiation-sensitive onium cation.

4. R １ 4. The radiation-sensitive composition according to claim 3, wherein is a trifluoromethyl group.

5. n １ 4. The radiation-sensitive composition according to claim 3, wherein is an integer of 2 to 5.

6. R １ is a trifluoromethyl group, and n １ 4. The radiation-sensitive composition according to claim 3, wherein is an integer of 2 to 5.

7. n ２ 4. The radiation-sensitive composition according to claim 3, wherein is an integer of 1 to 5.

8. n ３ is an integer from 1 to 5, and R ３ 4. The radiation-sensitive composition according to claim 3, wherein is a carboxy group.

9. n ３ is an integer from 1 to 5, and R ３ 4. The radiation-sensitive composition according to claim 3, wherein is a hydroxy group.

10. n ５ 4. The radiation-sensitive composition according to claim 3, wherein is an integer of 2 to 10.

11. A method for forming a resist pattern, comprising the steps of: applying the radiation-sensitive composition according to any one of claims 1 to 10 directly or indirectly to a substrate; exposing a resist film formed by the application; and developing the exposed resist film.

12. A compound having a sulfonate anion and a radiation-sensitive onium cation, wherein the sulfonate anion has an aromatic ring in which at least one hydrogen atom is substituted with a substituent, and at least one group selected from the group consisting of a hydroxy group and a carboxy group, and the substituent is at least one group selected from the group consisting of a fluorinated alkyl group, an unsubstituted tertiary alkyl group, and a trialkylsilyl group, and the radiation-sensitive onium cation has an aromatic ring in which at least one hydrogen atom is substituted with a fluoro group or a fluorinated alkyl group.

Images