JP2017181696A - Radiation-sensitive resin composition and method for forming resist pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation-sensitive resin composition excellent in sensitivity, LWR performance, and film thickness reduction-preventing properties.SOLUTION: This invention relates to a radiation-sensitive resin composition, comprising: a first polymer that has a carbon atom constituting a ring structure in a main chain, and has an aromatic ring and an acid-dissociable group in a side chain; and a radiation-sensitive acid generator. Preferably, the first polymer has a structural unit expressed by the following formula (1-1), (1-2), or (1-3). In the following formula, the ring structure represents: an alicyclic ring structure with a 4- to 20-membered ring, which has an aromatic ring and an acid-dissociable group; or an aliphatic heterocyclic structure with a 4- to 20-membered ring, which has an aromatic ring and an acid-dissociable group.SELECTED DRAWING: None

Description

  The present invention relates to a radiation-sensitive resin composition and a resist pattern forming method.

  With the miniaturization of various electronic device structures such as semiconductor devices and liquid crystal devices, further miniaturization of resist patterns in the lithography process is required, and various radiation-sensitive resin compositions have been studied. Such a radiation sensitive resin composition generates an acid in an exposed part by irradiation with exposure light such as deep ultraviolet light such as ArF excimer laser, extreme ultraviolet light (EUV), X-ray, electron beam, etc. The action causes a difference in the dissolution rate of the exposed portion and the unexposed portion with respect to the developer, thereby forming a resist pattern on the substrate.

  Such a radiation sensitive resin composition is not only excellent in resolution and the like, but also excellent in LWR (Line Width Roughness) performance and capable of obtaining a highly accurate pattern. High sensitivity to exposure light such as Extreme Ultra Violet Rays (EUV), X-rays, and electron beams is required. In response to this requirement, various structures of the polymer contained in the radiation-sensitive resin composition have been studied. By having a lactone structure such as a butyrolactone structure or a norbornane lactone structure, the resist pattern can be adhered to the substrate. It is known that these properties can be improved while improving the performance (see JP-A-11-212265, JP-A-2003-5375 and JP-A-2008-83370).

  However, these conventional radiation-sensitive resin compositions cannot satisfy these requirements. In addition, recently, when forming a resist pattern, it is required that the thickness of the resist film is reduced, and it is also required to have excellent film reduction suppression performance. As a result, the above-described resist performances can be further improved. It has been demanded.

JP 11-212265 A JP 2003-5375 A JP 2008-83370 A

  This invention is made | formed based on the above situations, The objective is to provide the radiation sensitive resin composition and resist pattern formation method which are excellent in a sensitivity, LWR performance, and a film | membrane reduction inhibitory property. .

  The invention made in order to solve the above-mentioned problems is a first polymer having a carbon atom constituting a ring structure in the main chain and an aromatic ring and an acid-dissociable group in the side chain (hereinafter referred to as “[A ] Polymer ”and a radiation-sensitive acid generator (hereinafter also referred to as“ [B] acid generator ”).

  Another invention made to solve the above problems includes a step of coating the radiation-sensitive resin composition on one side of the substrate, a step of exposing a resist film obtained by the coating, and And a step of developing the exposed resist film.

  Here, “ring structure” means “a structure consisting only of atoms constituting the ring”, and depending on the aromaticity of the ring and the type of atoms constituting the ring, the alicyclic structure, aromatic ring structure, aliphatic heterostructure It is classified into a ring structure and an aromatic heterocyclic structure. The “ring structure having an aromatic ring and an acid dissociable group” means “a ring structure in which an aromatic ring and a group containing an acid dissociable group are bonded”. The aromatic ring of the “aromatic ring and acid dissociable group” in the side chain may be contained in the acid dissociable group. “Main chain” means the longest chain of atoms in a polymer. The “side chain” refers to an atom chain other than the main chain in the polymer. The “aromatic ring” is a concept including an aromatic carbocyclic ring and an aromatic heterocyclic ring. The “acid-dissociable group” refers to a group that substitutes a hydrogen atom of a hydroxy group, a carboxy group, a sulfo group, etc., and dissociates by the action of an acid.

  According to the radiation-sensitive resin composition and the resist pattern forming method of the present invention, a resist pattern with high sensitivity, low LWR, and small film loss can be formed. Therefore, the pattern forming method can be suitably used for a semiconductor device processing process and the like that are expected to be further miniaturized in the future.

<Radiation sensitive resin composition>
The radiation-sensitive resin composition contains a [A] polymer and a [B] acid generator. The radiation-sensitive resin composition may contain a [C] nitrogen-containing compound and / or a [D] solvent as suitable components, and may contain other optional components as long as the effects of the present invention are not impaired. May be. Hereinafter, each component will be described.

<[A] polymer>
[A] The polymer is a polymer having a carbon atom constituting the ring structure in the main chain and an aromatic ring and an acid dissociable group in the side chain. The said radiation sensitive resin composition is excellent in a sensitivity, LWR performance, and film | membrane reduction inhibitory property by containing the [A] polymer and [B] acid generator which have the said specific structure. The reason why the radiation-sensitive resin composition has the above-described configuration and exhibits the above-mentioned effects is not necessarily clear, but can be inferred as follows, for example. That is, since the [A] polymer has carbon atoms constituting the ring structure in the main chain, the rigidity is high, and [B] the diffusion length of the acid generated from the acid generator is reasonably short. And as a result, the LWR performance is improved. In addition, it is considered that the acid dissociable group in the [A] polymer is located away from the main chain and in the vicinity of the periphery of the [A] polymer. As a result, the ease of dissociation of the acid dissociable group is improved, and the sensitivity Will improve. Furthermore, since the [A] polymer has a ring structure in the main chain and an aromatic ring in the side chain, even if the acid-dissociable group is eliminated during formation of the resist pattern, Since it is considered that the coalescence is difficult to shrink, the film loss suppression property is improved.

[A] Examples of the ring structure having a carbon atom in the main chain of the polymer include a cyclopropane structure, a cyclobutane structure, a cyclopentane structure, a cyclohexane structure, a cycloheptane structure, a cyclooctane structure, a cyclodecane structure, a cyclopentene structure, and a cyclohexene structure. Monocyclic alicyclic structures such as
Alicyclic structures such as polycyclic alicyclic structures such as norbornane structure, bicyclodecane structure, adamantane structure, tricyclododecane structure, norbornene structure, bicyclodecene structure, tricyclododecene structure,
Aromatic carbocyclic structures such as benzene, naphthalene, and anthracene structures;
Azacyclopentane structure (including succinimide structure), azacyclohexane structure (including glutarimide structure), thiacyclopentane structure, thiacyclohexane structure, oxacyclopentane structure (including butyrolactone structure), oxacyclohexane structure (valero) Monocyclic aliphatic heterocyclic structures such as lactone structures);
Aliphatic heterocyclic structures such as polycyclic aliphatic heterocyclic structures such as azanorbornane structure, thianorbornane structure, oxanorbornane structure,
Examples thereof include aromatic heterocyclic structures such as a pyrrole structure, a pyridine structure, a thiophene structure, a furan structure, and a pyran structure. Among these, an alicyclic structure and an aliphatic heterocyclic structure are preferable, a monocyclic alicyclic structure and a monocyclic aliphatic heterocyclic structure are more preferable, and a cyclopentane structure, an oxacyclopentane structure, and an azacyclopentane structure. Further preferred.

[A] Examples of the aromatic ring in the polymer include aromatic carbocyclic rings such as a benzene ring, a naphthalene ring, and an anthracene ring;
Aromatic heterocycles such as a pyrrole ring, a pyridine ring, a thiophene ring, a furan structure, and a pyran structure are exemplified. Among these, an aromatic carbocyclic ring is preferable, and a benzene ring is more preferable.

  [A] As the acid dissociable group in the polymer, for example, a group that replaces a hydrogen atom such as a hydroxy group, a carboxy group, and a sulfo group, such as a t-butyl group, a 1-alkylcyclopentan-1-yl group, Examples include aryl-substituted or unsubstituted tertiary alkyl groups such as 2-alkyladamantan-2-yl group and 2-phenylpropan-2-yl group. As the acid dissociable group, a 1-alkylcycloalkane-1-yl group and a 2-arylpropan-2-yl group are preferable, and a 1-alkylcyclopentan-1-yl group and a 2-phenylpropan-2-yl group are preferable. Is more preferable.

  [A] The polymer is not particularly limited as long as it has a carbon atom constituting the ring structure in the main chain and has an aromatic ring and an acid dissociable group in the side chain, but constitutes the ring structure. It is preferable to have a structural unit (hereinafter also referred to as “structural unit (I)”) having a carbon atom in the main chain and an aromatic ring and an acid-dissociable group in the side chain.

  [A] The polymer is a structural unit other than the structural unit (I) in addition to the structural unit (I), the structural unit (II) having an acid-dissociable group, and the structural unit (III) containing a phenolic hydroxyl group. It is preferable to have a structural unit (IV) containing a fluorine atom, and other structural units may be included in addition to the structural units (I) to (IV). [A] The polymer may have one or more of the above structural units. Hereinafter, each structural unit will be described.

[Structural unit (I)]
The structural unit (I) is a structural unit having a carbon atom constituting a ring structure in the main chain and an aromatic ring and an acid dissociable group in the side chain.

  Examples of the structural unit (I) include a structural unit represented by the following formula (1-1) (hereinafter, also referred to as “structural unit (I-1)”) and a structure represented by the following formula (1-2). Examples thereof include a unit (hereinafter also referred to as “structural unit (I-2)”), a structural unit represented by the following formula (1-3) (hereinafter also referred to as “structural unit (I-3)”), and the like.

(Structural unit (I-1))
The structural unit (I-1) is a structural unit represented by the following formula (1-1).

In the above formula (1-1), ^{R 1} and ^{R 2} are each independently a monovalent organic group hydrogen atom or 1 to 10 carbon atoms. R ³ represents an alicyclic structure having 4 to 20 ring members having an aromatic ring and an acid dissociable group, or an aliphatic heterocyclic structure having 4 to 20 ring members having an aromatic ring and an acid dissociable group.

  “Organic group” refers to a group containing at least one carbon atom. The “hydrocarbon group” includes a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. The “hydrocarbon group” may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. The “chain hydrocarbon group” refers to a hydrocarbon group that does not include a cyclic structure but includes only a chain structure, and includes both a linear hydrocarbon group and a branched hydrocarbon group. The term “alicyclic hydrocarbon group” refers to a hydrocarbon group that includes only an alicyclic structure as a ring structure and does not include an aromatic ring structure, and includes a monocyclic alicyclic hydrocarbon group and a polycyclic alicyclic group. Includes both hydrocarbon groups. However, it is not necessary to be composed only of the alicyclic structure, and a part thereof may include a chain structure. “Aromatic hydrocarbon group” refers to a hydrocarbon group containing an aromatic ring structure as a ring structure. However, it is not necessary to be composed only of an aromatic ring structure, and a part thereof may include a chain structure or an alicyclic structure. “Number of ring members” means the number of atoms constituting the ring of the alicyclic structure, aromatic ring structure, aliphatic heterocyclic structure and aromatic heterocyclic structure, and in the case of polycyclic, the number of atoms constituting this polycyclic ring Say.

Examples of the monovalent organic group having 1 to 10 carbon atoms represented by R ¹ and R ² include, for example, a monovalent hydrocarbon group having 1 to 10 carbon atoms, and the carbon-carbon or bond side of the hydrocarbon group. A group (α) containing a divalent heteroatom-containing group at the terminal thereof, a group obtained by substituting a part or all of the hydrogen atoms of the hydrocarbon group and group (α) with a monovalent heteroatom-containing group, and the like. It is done.

  Examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms include a monovalent chain hydrocarbon group having 1 to 10 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 10 carbon atoms, and 6 to 6 carbon atoms. 10 monovalent aromatic hydrocarbon groups and the like.

Examples of the monovalent chain hydrocarbon group having 1 to 10 carbon atoms include alkyl groups such as a methyl group, an ethyl group, an n-propyl group, and an i-propyl group;
An alkenyl group such as an ethenyl group, a propenyl group, a butenyl group;
Examples thereof include alkynyl groups such as ethynyl group, propynyl group and butynyl group.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 10 carbon atoms include monocyclic monovalent alicyclic saturated hydrocarbon groups such as a cyclopentyl group and a cyclohexyl group;
Monocyclic monovalent alicyclic unsaturated hydrocarbon groups such as cyclopentenyl group and cyclohexenyl group;
A polycyclic monovalent alicyclic saturated hydrocarbon group such as a norbornyl group, an adamantyl group and a tricyclodecyl group;
Examples thereof include polycyclic monovalent alicyclic unsaturated hydrocarbon groups such as a norbornenyl group and a tricyclodecenyl group.

Examples of the monovalent aromatic hydrocarbon group having 6 to 10 carbon atoms include aryl groups such as a phenyl group, a tolyl group, a xylyl group, and a naphthyl group;
Examples include aralkyl groups such as benzyl group and phenethyl group.

  Examples of the hetero atom constituting the monovalent and divalent heteroatom-containing group include an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom, a silicon atom, and a halogen atom. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

  Examples of the divalent heteroatom-containing group include —O—, —CO—, —S—, —CS—, —NR′—, a group in which two or more of these are combined, and the like. R 'is a hydrogen atom or a monovalent hydrocarbon group. Of these, -O- is preferred.

  Examples of the monovalent heteroatom-containing group include halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom, hydroxy group, carboxy group, cyano group, amino group and sulfanyl group (—SH). Among these, a fluorine atom is preferable.

R ¹ and R ² are preferably a hydrogen atom and a monovalent hydrocarbon group having 1 to 10 carbon atoms, more preferably a hydrogen atom and an alkyl group having 1 to 10 carbon atoms, still more preferably a hydrogen atom and a methyl group, A hydrogen atom is particularly preferred.

Examples of the alicyclic structure having 4 to 20 ring members having an aromatic ring and an acid dissociable group represented by R ³ include a cyclobutane structure, a cyclopentane structure, a cyclohexane structure, a cyclooctane structure, a cyclodecane structure, a norbornane structure, and an adamantane structure. And the like include a structure in which a group containing an aromatic ring and an acid-dissociable group is bonded.

Examples of the aliphatic heterocyclic structure having 4 to 20 ring members having an aromatic ring and an acid dissociable group represented by R ³ include an azacyclopentane structure, an azacyclohexane structure, a thiacyclopentane structure, a thiacyclohexane structure, an oxacyclo Examples include a structure in which an aromatic ring and a group containing an acid dissociable group are bonded to a pentane structure, an oxacyclohexane structure, or the like.

R ³ is preferably an alicyclic structure having 4 to 6 ring members and an aliphatic heterocyclic structure having 4 to 6 ring members, more preferably a cyclopentane structure, an azacyclopentane structure or an oxacyclopentane structure, a cyclopentane structure, A succinimide structure and a butyrolactone structure are more preferable.

  Examples of the structural unit (I-1) include a structural unit represented by the following formula (1-1-1) (hereinafter also referred to as “structural unit (I-1-1)”).

In said formula (1-1-1), R < ¹ > and R < ² > are synonymous with the said formula (1-1). R ¹² and R ¹³ are each independently a hydrogen atom, a halogen atom, a hydroxy group, or a monovalent organic group having 1 to 20 carbon atoms. n is an integer of 0-4. When n is 2 or more, the plurality of R ¹² may be the same or different, and the plurality of R ¹³ may be the same or different. Even if two or more of one or more R ¹² and one or more R ¹³ represent a ring structure having 3 to 20 ring members that is formed together with a carbon atom or a carbon chain to which they are combined and bonded to each other. Good. R ¹⁴ is a divalent group containing an aromatic ring and an acid dissociable group.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ¹² and R ¹³ include the same groups as the monovalent organic group represented by R ¹ and R ² above.

R ¹² and R ¹³ are preferably a hydrogen atom.

Examples of R ¹⁴ in the above formula (1-1-1) include groups represented by the following formula (2-1), (2-2), (2-3) or (2-4). .

In said formula (2-1), R < ¹⁵ > is a hydrogen atom or a C1-C20 monovalent organic group. Ar ¹ is a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 20 ring members. R ¹⁶ is a single bond or a divalent organic group having 1 to 20 carbon atoms. R ^A is a monovalent acid dissociable group.

In the above formula (2-2), Ar ² is a substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 to 20 ring members. R ¹⁷ is a single bond or a divalent organic group having 1 to 20 carbon atoms. R ^B is a monovalent acid dissociable group.

In the formula ^{(2-3), R 18} is a tetravalent group constituting an alicyclic structure ring members 3 to 20 together with the carbon atoms. R ¹⁹ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. Ar ³ is a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 20 ring members. R ²⁰ is a single bond or a divalent organic group having 1 to 20 carbon atoms. R ^C is a monovalent acid dissociable group.

In said formula (2-4), R < ²¹ > is a tetravalent group which comprises a C3-C20 alicyclic structure with a carbon atom. Ar ⁴ is a substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 to 20 ring members. R ²² is a single bond or a divalent organic group having 1 to 20 carbon atoms. ^RD is a monovalent acid dissociable group.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ¹⁹ include the same groups as those exemplified as the monovalent organic group represented by R ¹ and R ² above. Examples of the divalent organic group having 1 to 20 carbon atoms represented by R ¹⁵ , R ¹⁷ and R ²² include one hydrogen atom from a monovalent organic group having 1 to 20 carbon atoms represented by R ^19. And the like except for.

As monovalent aromatic hydrocarbon groups having 6 to 20 ring members represented by Ar ² and Ar ⁴ , for example, among the monovalent aromatic hydrocarbon groups exemplified as R ¹ and R ² above, the number of ring members is 6 -20 or the like. Examples of the divalent aromatic hydrocarbon group having 6 to 20 ring members represented by Ar ¹ and Ar ³ include, for example, the monovalent aromatic hydrocarbon having 6 to 20 ring members represented by Ar ² and Ar ^4. And a group obtained by removing one hydrogen atom from a group. Examples of the substituent for the aromatic hydrocarbon group of Ar ^{1 to} Ar ⁴ include a halogen atom and a hydroxy group.

Examples of the alicyclic structure having 3 to 20 ring members constituted by a tetravalent group represented by R ¹⁸ or R ²¹ and a carbon atom include 3 to 3 ring members exemplified as the ring structure in the above-mentioned [A] polymer. The structure similar to 20 alicyclic structures, etc. are mentioned.

R ^{15 in the} above formula (2-1) is preferably a hydrogen atom and a monovalent hydrocarbon group, more preferably a hydrogen atom, a monovalent chain hydrocarbon group and a monovalent alicyclic hydrocarbon group, A hydrogen atom, an alkyl group, and a monovalent alicyclic saturated hydrocarbon group are more preferable, and a hydrogen atom is particularly preferable. Ar ¹ is preferably a substituted or unsubstituted divalent aromatic hydrocarbon group, more preferably a substituted or unsubstituted arenediyl group, still more preferably a substituted or unsubstituted benzenediyl group, and particularly preferably a benzenediyl group. . R ¹⁶ is preferably a divalent organic group, preferably a divalent oxyhydrocarbon group, more preferably an oxyalkanediyl group, and particularly preferably an oxymethanediyl group. R ^A is preferably a t-alkyl group, more preferably a monovalent alicyclic saturated hydrocarbon group in which the carbon atom of the bond is alkyl-substituted, more preferably a 1-alkylcycloalkane-1-yl group. -Ethylcyclopentan-1-yl group is particularly preferred.

Ar ^{2 in the} above formula (2-2) is preferably a substituted or unsubstituted aryl group, more preferably a substituted or unsubstituted phenyl group, and even more preferably a phenyl group. R ¹⁷ is preferably a divalent organic group, more preferably a divalent hydrocarbon group, still more preferably a divalent chain hydrocarbon group, particularly preferably an alkanediyl group, and particularly preferably a methanediyl group and an ethanediyl group. preferable. R ^B is preferably an aromatic ring-substituted or unsubstituted t-alkyl group, more preferably a monovalent alicyclic saturated hydrocarbon group or 2-arylpropan-2-yl group in which the carbon atom of the bond is alkyl-substituted. A 1-alkylcycloalkane-1-yl group and a 2-phenylpropan-2-yl group are more preferable, and a 1-ethylcyclopentan-1-yl group and a 2-phenylpropan-2-yl group are particularly preferable.

R ^{18 in the} above formula (2-3) is preferably a tetravalent group constituting a cyclopentane structure or a cyclohexane structure together with a carbon atom. R ¹⁹ is preferably a hydrogen atom or a monovalent hydrocarbon group, more preferably a hydrogen atom, a monovalent chain hydrocarbon group or a monovalent alicyclic hydrocarbon group, a hydrogen atom, an alkyl group or a monovalent group. Are more preferable, and a hydrogen atom is particularly preferable. Ar ³ is preferably a substituted or unsubstituted divalent aromatic hydrocarbon group, more preferably a substituted or unsubstituted arenediyl group, still more preferably a substituted or unsubstituted benzenediyl group, and particularly preferably a benzenediyl group. . R ²⁰ is preferably a divalent organic group, preferably a divalent oxyhydrocarbon group, more preferably an oxyalkanediyl group, and particularly preferably an oxymethanediyl group. R ^C is preferably a t-alkyl group, more preferably a monovalent alicyclic saturated hydrocarbon group in which the carbon atom of the bond is substituted with an alkyl, more preferably a 1-alkylcycloalkane-1-yl group. -Ethylcyclopentan-1-yl group is particularly preferred.

As R < ²¹ > of said Formula (2-4), the tetravalent group which comprises a cyclopentane structure or a cyclohexane structure with a carbon atom is preferable. Ar ⁴ is preferably a substituted or unsubstituted aryl group, more preferably a substituted or unsubstituted phenyl group, and still more preferably a phenyl group. R ²² is preferably a divalent organic group, more preferably a divalent hydrocarbon group, further preferably a divalent chain hydrocarbon group, particularly preferably an alkanediyl group, and particularly preferably a methanediyl group. ^RD is preferably a t-alkyl group, more preferably a monovalent alicyclic saturated hydrocarbon group in which the carbon atom of the bond is alkyl-substituted, more preferably a 1-alkylcycloalkane-1-yl group. -Ethylcyclopentan-1-yl group is particularly preferred.

As R ¹⁴ in the structural unit (I-1), a group represented by the above formula (2-1) and a group represented by the above formula (2-2) are preferable.

(Structural unit (I-2))
The structural unit (I-2) is a structural unit represented by the following formula (1-2).

In said formula (1-2), R < ⁴ > -R < ⁷ > is respectively independently a hydrogen atom or a C1-C10 monovalent organic group. R ⁸ represents an alicyclic structure having 4 to 20 ring members having an aromatic ring and an acid dissociable group, or an aliphatic heterocyclic structure having 4 to 20 ring members having an aromatic ring and an acid dissociable group.

Examples of the monovalent organic group having 1 to 10 carbon atoms represented by R ^{4 to} R ⁷ include the same groups exemplified as the above R ¹ and R ² .

R ^{4 to} R ⁷ are preferably a hydrogen atom and a monovalent hydrocarbon group, more preferably a hydrogen atom and a chain hydrocarbon group, still more preferably a hydrogen atom and an alkyl group, particularly preferably a hydrogen atom and a methyl group, Particularly preferred is a hydrogen atom.

Examples of the alicyclic structure having 4 to 20 ring members having an aromatic ring and an acid dissociable group represented by R ⁸ include the same structures as those exemplified as R ³ above.

Examples of the aliphatic heterocyclic structure having 4 to 20 ring members having an aromatic ring and an acid dissociable group represented by R ⁸ include structures similar to those exemplified as R ³ above.

  Examples of the structural unit (I-2) include a structural unit represented by the following formula (1-2-1) (hereinafter also referred to as “structural unit (I-2-1)”).

In said formula (1-2-1), R < ⁴ > -R < ⁷ > is synonymous with said formula (1-2). R ²³ is a divalent organic group containing an aromatic ring and an acid dissociable group. m is an integer of 0-5.

  As m, 0-2 are preferable, 1 and 2 are more preferable, and 1 is further more preferable.

Examples of the divalent organic group containing an aromatic ring and an acid dissociable group represented by R ²³ include a methanediyl group to which a group containing an aromatic ring and an acid dissociable group is bonded. R ²³ is preferably a 2-arylpropan-2-yloxycarbonylmethanediyl group, more preferably a 2-phenylpropan-2-ylcarbonylmethanediyl group.

  In the case where the structural unit (I-2) is formed by ring-opening metathesis polymerization (ROMP) of a cyclic olefin compound, the structure that is usually composed of an ethanediyl group or an ethenediyl group in the [A] polymer The unit is adjacent to the structural unit (I-2)

(Structural unit (I-3))
The structural unit (I-3) is a structural unit represented by the following formula (1-3).

In the above formula (1-3), ^{R 9} and ^{R 10} are each independently a monovalent organic group hydrogen atom or 1 to 10 carbon atoms. R ¹¹ represents an alicyclic structure having 4 to 20 ring members having an aromatic ring and an acid dissociable group, or an aliphatic heterocyclic structure having 4 to 20 ring members having an aromatic ring and an acid dissociable group.

Examples of the monovalent organic group having 1 to 10 carbon atoms represented by R ⁹ and R ¹⁰ include the same groups exemplified as the above R ¹ and R ² .

R ⁹ and R ¹⁰ are preferably a hydrogen atom and a monovalent hydrocarbon group, more preferably a hydrogen atom and a chain hydrocarbon group, still more preferably a hydrogen atom and an alkyl group, particularly preferably a hydrogen atom and a methyl group, Particularly preferred is a hydrogen atom.

Examples of the alicyclic structure having 4 to 20 ring members having an aromatic ring and an acid dissociable group represented by R ¹¹ include structures similar to those exemplified as R ³ above.

Examples of the aliphatic heterocyclic structure having 4 to 20 ring members having an aromatic ring and an acid dissociable group represented by R ¹¹ include structures similar to those exemplified as R ³ above.

  Examples of the structural unit (I-3) include a structural unit represented by the following formula (1-3-1) (hereinafter also referred to as “structural unit (I-3-1)”).

In the above formula (1-3-1), ^{R 9} and ^{R 10} is as defined in the above formula (1-3). R ²⁴ is a monovalent organic group containing an aromatic ring and an acid dissociable group. k is an integer of 0-5.

The monovalent organic group containing an aromatic ring and an acid dissociable group represented by R ²⁴ is preferably, for example, a methyl group to which a monovalent group containing an aromatic ring and an acid dissociable group is bonded, and an acid containing an aromatic ring. Methyl bonded with a monovalent group having a dissociable group is more preferable, 2-arylpropan-2-yloxycarbonylmethyl group is more preferable, and 2-phenylpropan-2-yloxycarbonylmethyl group is particularly preferable.

  As the compound that gives the structural unit (I), for example, compounds represented by the following formulas (i-1-1) to (i-1-3) that give the structural unit (I-1) are structural units ( The compound represented by the following formula (i-2-1) as the compound that provides I-2) is represented by the following formula (i-3-1) as the compound that provides the structural unit (I-3). Compounds and the like.

  As a minimum of the content rate of structural unit (I), 1 mol% is preferable with respect to all the structural units which comprise a [A] polymer, 5 mol% is more preferable, 10 mol% is further more preferable, 15 mol % Is particularly preferred. As an upper limit of the content rate of structural unit (I), 100 mol% is preferable, 50 mol% is more preferable, 30 mol% is further more preferable, 25 mol% is especially preferable. By making the said content rate into the said range, the LWR performance and the film | membrane reduction inhibitory property of the said radiation sensitive resin composition can be improved more.

[Structural unit (II)]
The structural unit (II) is a structural unit other than the structural unit (I) and includes an acid dissociable group. Examples of the structural unit (II) include a structural unit represented by the following formula (3). The group represented by —CR ³² R ³³ R ³⁴ in the following formula (3) is an acid dissociable group. In the radiation-sensitive resin composition, the [A] polymer has the structural unit (II), whereby the sensitivity is improved and, as a result, the LWR performance can be improved.

In the formula (3), R ³¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ³² is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ³³ and R ³⁴ are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or 3 to 3 carbon atoms composed of these groups combined with the carbon atom to which they are bonded. 20 alicyclic structures are represented.

R ³¹ is preferably a hydrogen atom and a methyl group, more preferably a methyl group, from the viewpoint of copolymerization of the monomer that gives the structural unit (II).

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ³² , R ³³ and R ³⁴ include the monovalent hydrocarbon groups exemplified as R ¹ and R ^{2 in} the above formula (1-1). And the like groups.

  Examples of the alicyclic structure having 3 to 20 carbon atoms constituted by the carbon atoms to which these groups are combined with each other are exemplified as a ring structure having a carbon atom in the main chain of the above-mentioned [A] polymer. The thing similar to an alicyclic structure is mentioned.

  As the structural unit (II), structural units represented by the following formulas (3-1) to (3-4) (hereinafter also referred to as “structural units (II-1) to (II-4)”) are preferable. .

In the above formulas (3-1) to (3-4), R ^{31 to} R ³⁴ have the same meaning as the above formula (3). i and j are each independently an integer of 1 to 4.

  Examples of the structural unit (II) include a structural unit represented by the following formula.

In the above formula, R ³¹ has the same meaning as the above formula (3).

  As the structural unit (II), structural units (II-1) and (II-3) are preferable, and structural units derived from 1-alkylcyclopentan-1-yl (meth) acrylate and 2-arylpropane-2- A structural unit derived from yl (meth) acrylate is more preferable, and a structural unit derived from 1-ethylcyclopentan-1-yl (meth) acrylate and a structure derived from 2-phenylpropan-2-yl (meth) acrylate. Further preferred.

  [A] When the polymer has the structural unit (II), the lower limit of the content ratio of the structural unit (II) is preferably 5 mol% with respect to the total structural units constituting the [A] polymer. % Is more preferable, and 15 mol% is more preferable. As an upper limit of the said content rate, 80 mol% is preferable, 60 mol% is more preferable, and 40 mol% is further more preferable. By making the said content rate into the said range, the sensitivity of the said radiation sensitive resin composition improves more, and, as a result, LWR performance can further be improved.

[Structural unit (III)]
The structural unit (III) is a structural unit containing a phenolic hydroxyl group. The said radiation sensitive resin composition can further improve the sensitivity in the case of exposure of EUV, an electron beam, KrF, etc. by having further structural unit (III). Examples of the structural unit (III) include a structural unit represented by the following formula (a).

In said formula (a), ^R41 is a hydrogen atom or a methyl group. L ² is a single bond or a divalent organic group having 1 to 20 carbon atoms. R ⁴² is a monovalent organic group having 1 to 20 carbon atoms. p is an integer of 0-2. q is an integer of 0-9. When q is 2 or more, the plurality of R ⁴² may be the same or different. r is an integer of 1 to 3.

  As the structural unit (III), for example, structural units represented by the following formulas (a-1) to (a-7) (hereinafter also referred to as “structural units (III-1) to (III-7)”) and the like Is mentioned.

In said formula (a-1)-(a-7), ^R41 is synonymous with the said formula (a).

  Among these, the structural unit (III-1) and the structural unit (III-5) are preferable.

  [A] When the polymer has the structural unit (III), the lower limit of the content ratio of the structural unit (III) is preferably 10 mol% with respect to all the structural units constituting the [A] polymer. Mole% is more preferable, and 30 mol% is more preferable. As an upper limit of the said content rate, 80 mol% is preferable, 60 mol% is more preferable, and 50 mol% is further more preferable. By making the content rate of structural unit (III) into the said range, the sensitivity in the case of exposure of EUV, an electron beam, KrF, etc. can further be improved.

  The structural units (III-1) to (III-4) and (III-7) are monomers in which the hydrogen atom of the —OH group of styrene containing a phenolic hydroxyl group such as hydroxystyrene is substituted with an acetyl group or the like. After the polymerization, etc., the obtained polymer can be formed by performing a hydrolysis reaction in the presence of a base such as an amine.

(Structural unit (IV))
The structural unit (IV) is a structural unit containing a fluorine atom (excluding those corresponding to the structural units (I) to (III)). The said radiation sensitive resin composition can further improve the sensitivity in the case of exposure of EUV, an electron beam, KrF, etc. by having further structural unit (IV). Examples of the structural unit (IV) include a structural unit represented by the following formula (b).

In said formula (b), ^R51 is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. L ³ is a single bond, —O— or a divalent organic group having 1 to 20 carbon atoms. R ⁵² is a single bond or a divalent organic group having 1 to 20 carbon atoms.

R ⁵¹ is preferably a hydrogen atom or a methyl group from the viewpoint of the copolymerizability of the monomer that gives the structural unit (IV).

Examples of the divalent organic group having 1 to 20 carbon atoms represented by L ³ include —COO— and —CONH—. Of these, -COO- is preferable.

Examples of the divalent organic group having 1 to 20 carbon atoms represented by R ⁵² include a divalent hydrocarbon group. Among these, a divalent alicyclic hydrocarbon group and a divalent aromatic hydrocarbon group are preferable, a divalent polycyclic alicyclic saturated hydrocarbon group and an arenediyl group are more preferable, a norbornanediyl group and More preferred is a benzenediyl group.

  As the structural unit (IV), structural units derived from p- (hydroxy-1,1,1,3,3,3-hexafluoropropan-2-yl) styrene and 5- (hydroxy-1,1,1) , 3,3,3-hexafluoropropan-2-ylmethanediylnorbornan-2-yl) (meth) acrylate is preferred.

  [A] When a polymer has a structural unit (IV), as a minimum of the content rate of a structural unit (IV), 5 mol% is preferable with respect to all the structural units which comprise a [A] polymer, 10 Mole% is more preferable, and 15 mol% is more preferable. As an upper limit of the said content rate, 80 mol% is preferable, 50 mol% is more preferable, and 30 mol% is further more preferable. By making the content rate of structural unit (IIV) into the said range, the sensitivity in the case of exposure of EUV, an electron beam, KrF, etc. can further be improved.

(Other structural units)
Other structural units include, for example, a structural unit containing a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination thereof, an alcoholic hydroxyl group, an amino group, a cyano group, a nitro group, a sulfonamide group, or a combination thereof. Etc. [A] The polymer can further improve the adhesion between the resist pattern and the substrate by having other structural units.

  [A] When the polymer has other structural units, the upper limit of the content ratio of the other structural units is preferably 30 mol%, preferably 10 mol%, based on all structural units constituting the [A] polymer. Is more preferable, and 5 mol% is further more preferable.

  [A] The lower limit of the content of the polymer is preferably 70% by mass, more preferably 80% by mass with respect to the total solid content of the radiation-sensitive resin composition (total of components other than the solvent), 85 More preferred is mass%.

<[A] Polymer Synthesis Method>
[A] The polymer can be synthesized, for example, by polymerizing monomers that give each structural unit in a suitable solvent using a radical polymerization initiator or the like.

  Examples of the radical polymerization initiator include azobisisobutyronitrile (AIBN), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2-cyclopropylpropylene). Pionitrile), azo radical initiators such as 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2′-azobisisobutyrate; benzoyl peroxide, t-butyl hydroperoxide, And peroxide radical initiators such as cumene hydroperoxide. Of these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferred, and AIBN is more preferred. These radical polymerization initiators can be used alone or in combination of two or more.

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

  As a minimum of reaction temperature in superposition | polymerization, 40 degreeC is preferable and 50 degreeC is more preferable. As an upper limit of the said reaction temperature, 150 degreeC is preferable and 120 degreeC is more preferable. As a minimum of reaction time in superposition | polymerization, 1 hour is preferable and 2 hours is more preferable. The upper limit of the reaction time is preferably 48 hours, more preferably 24 hours.

  The [A] polymer can also be synthesized by subjecting a cyclic olefin compound to ring-opening metathesis polymerization in a solvent such as toluene in the presence of a catalyst such as a ruthenium complex.

  [A] The lower limit of the weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) of the polymer is preferably 1,000, more preferably 2,000, still more preferably 3,000, 000 is particularly preferred. The upper limit of Mw is preferably 50,000, more preferably 30,000, still more preferably 20,000, and particularly preferably 10,000. [A] By making Mw of a polymer into the said range, the applicability | paintability of the said radiation sensitive resin composition can be improved, As a result, development defect inhibitory property can be improved more.

  [A] The upper limit of the ratio (Mw / Mn) of Mw to the number average molecular weight (Mn) in terms of polystyrene by GPC of the polymer is preferably 5, more preferably 3, still more preferably 2, and particularly preferably 1.7. . The lower limit of the ratio is usually 1 and preferably 1.1.

Mw and Mn of the polymer in this specification are values measured using gel permeation chromatography (GPC) under the following conditions.
GPC column: 2 "G2000HXL" from Tosoh Corporation, 1 "G3000HXL" and 1 "G4000HXL" Column temperature: 40 ° C
Elution solvent: Tetrahydrofuran (Wako Pure Chemical Industries)
Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass
Sample injection volume: 100 μL
Detector: Differential refractometer Standard material: Monodisperse polystyrene

<[B] Acid generator>
[B] The acid generator is a substance that generates an acid upon exposure. The contained form of the [B] acid generator in the radiation-sensitive resin composition may be a low molecular compound form (hereinafter also referred to as “[B] acid generator” as appropriate), as described later. It may be in the form of an acid generating group incorporated as a part, or in both forms.

  [B] Examples of the acid generator include onium salt compounds, N-sulfonyloxyimide compounds, sulfonimide compounds, halogen-containing compounds, and diazoketone compounds.

  Examples of the onium salt compounds include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, pyridinium salts, and the like.

  [B] Specific examples of the acid generator include compounds described in paragraphs [0080] to [0113] of JP-A-2009-134088.

  [B] Examples of the acid generated from the acid generator include sulfonic acid, imidic acid, amide acid, methide acid, phosphinic acid, and carboxylic acid. Among these, sulfonic acid, imide acid, amic acid, methide acid and carboxylic acid are preferable, and sulfonic acid and carboxylic acid are more preferable.

  [B] The acid generator preferably has a ring structure. As a minimum of the number of ring members of a ring structure, 6 are preferred, 7 is more preferred, 8 is still more preferred, 9 is especially preferred, and 10 is still especially preferred. The upper limit of the number of ring members is 20, for example. [B] By setting the number of ring members of the ring structure of the acid generator within the above range, [B] the diffusion length of the acid generated from the acid generator is considered to be appropriately shortened. As a result, the radiation-sensitive resin The LWR performance of the composition can be further improved.

([B1] acid generator)
Examples of the [B] acid generator include a compound represented by the following formula (4) (hereinafter also referred to as “[B1] acid generator”). [B1] The acid-dissociable group of the [A] polymer and the like is dissociated by the acid generated from the acid generator to generate a carboxy group, a hydroxy group, etc., and the solubility of the [A] polymer in the developer is lowered. Therefore, a resist pattern can be formed from the radiation sensitive resin composition.

In the above formula (4), A ⁻ represents a monovalent sulfonate anion, a monovalent imido acid anion, a monovalent amidate anion, or a monovalent methide acid anion. Z ⁺ is a monovalent radiation-sensitive onium cation.

[B1] acid generator, the above equation in (4) A ^- If the sulfonate anion (hereinafter, also referred to as "[B1a] acid generator"), a sulfonic acid is generated. A ^- is the case of the imide anion (hereinafter, also referred to as "[B1b] acid generator"), imide acid produced. A ^- is the case of the amide anion (hereinafter, also referred to as "[B1c] acid generator"), an amide acid occurs. A ^- is the case of the methide anion (hereinafter, also referred to as "[B1d] acid generator"), methide acid is generated.

  [B1a] Examples of the acid generator include a compound represented by the following formula (4-1) (hereinafter also referred to as “compound (4-1)”). [B1] When the acid generator has the following structure, the diffusion length of the acid generated by exposure in the resist film is appropriately shortened due to the interaction with the structural unit (I) of the polymer [A]. As a result, the LWR performance and the like of the radiation sensitive resin composition can be further improved.

In the above formula (4-1), R ^p1 is a monovalent group containing a ring structure having 6 or more ring members. R ^p2 is a divalent linking group. R ^p3 and R ^p4 are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. R ^p5 and R ^p6 are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. n ^p1 is an integer of 0 to 10. n ^p2 is an integer of 0 to 10. n ^p3 is an integer of 0 to 10. However, n ^p1 + n ^p2 + n ^p3 is 1 or more and 30 or less. When n ^p1 is 2 or more, the plurality of R ^p2 may be the same or different. When n ^p2 is 2 or more, the plurality of R ^p3 may be the same or different, and the plurality of R ^p4 may be the same or different. When n ^p3 is 2 or more, the plurality of R ^p5 may be the same or different, and the plurality of R ^p6 may be the same or different. Z ⁺ has the same ^{meaning as} in the above formula (3).

Examples of the monovalent group including a ring structure having 6 or more ring members represented by R ^p1 include a monovalent group including an alicyclic structure having 6 or more ring members and an aliphatic heterocyclic structure having 6 or more ring members. A monovalent group, a monovalent group containing an aromatic ring structure having 6 or more ring members, a monovalent group containing an aromatic heterocyclic structure having 6 or more ring members, and the like.

Examples of the alicyclic structure having 6 or more ring members include monocyclic saturated alicyclic structures such as a cyclohexane structure, a cycloheptane structure, a cyclooctane structure, a cyclononane structure, a cyclodecane structure, and a cyclododecane structure;
Monocyclic unsaturated alicyclic structures such as cyclohexene structure, cycloheptene structure, cyclooctene structure, cyclodecene structure;
Polycyclic saturated alicyclic structures such as norbornane structure, adamantane structure, tricyclodecane structure and tetracyclododecane structure;
Examples thereof include polycyclic unsaturated alicyclic structures such as a norbornene structure and a tricyclodecene structure.

Examples of the aliphatic heterocyclic structure having 6 or more ring members include lactone structures such as a hexanolactone structure and a norbornane lactone structure;
Sultone structures such as hexanosultone structure and norbornane sultone structure;
An oxygen atom-containing heterocyclic structure such as an oxacycloheptane structure or an oxanorbornane structure;
Nitrogen atom-containing heterocyclic structures such as azacyclohexane structure and diazabicyclooctane structure;
Examples thereof include a sulfur atom-containing heterocyclic structure having a thiacyclohexane structure and a thianorbornane structure.

  Examples of the aromatic ring structure having 6 or more ring members include a benzene structure, a naphthalene structure, a phenanthrene structure, and an anthracene structure.

Examples of aromatic heterocyclic structures having 6 or more ring members include oxygen atom-containing heterocyclic structures such as furan structures, pyran structures, and benzopyran structures;
Examples thereof include a nitrogen atom-containing heterocyclic structure such as a pyridine structure, a pyrimidine structure and an indole structure.

The lower limit of the number of ring members of the ring structure of R ^p1 is preferably 7, more preferably 8, more preferably 9, and particularly preferably 10. The upper limit of the number of ring members is preferably 15, more preferably 14, more preferably 13, and particularly preferably 12. By setting the number of ring members in the above range, the acid diffusion length can be further appropriately shortened, and as a result, the LWR performance and the like of the radiation-sensitive resin composition can be further improved.

A part or all of the hydrogen atoms ^{contained in} the ring structure of R ^p1 may be substituted with a substituent. Examples of the substituent include halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom, hydroxy group, carboxy group, cyano group, nitro group, alkoxy group, alkoxycarbonyl group, alkoxycarbonyloxy group, acyl group, Examples include an acyloxy group. Of these, a hydroxy group is preferred.

R ^p1 is preferably a monovalent group containing an alicyclic structure having 6 or more ring members and a monovalent group containing an aliphatic heterocyclic structure having 6 or more ring members, and 1 containing an alicyclic structure having 9 or more ring members. And a monovalent group containing an aliphatic heterocyclic structure having 9 or more ring members, an adamantyl group, a hydroxyadamantyl group, a norbornane lactone-yl group, a norbornane sultone-yl group, and 5-oxo-4-oxa A tricyclo [4.3.1.1 ^3,8 ] undecan-yl group is more preferred, and an adamantyl group is particularly preferred.

Examples of the divalent linking group represented by R ^p2 include a carbonyl group, an ether group, a carbonyloxy group, a sulfide group, a thiocarbonyl group, a sulfonyl group, and a divalent hydrocarbon group. Among these, a carbonyloxy group, a sulfonyl group, an alkanediyl group and a cycloalkanediyl group are preferred, a carbonyloxy group and a cycloalkanediyl group are more preferred, a carbonyloxy group and a norbornanediyl group are more preferred, and a carbonyloxy group is preferred. Particularly preferred.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^p3 and R ^p4 include an alkyl group having 1 to 20 carbon atoms. Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by R ^p3 and R ^p4 include a fluorinated alkyl group having 1 to 20 carbon atoms. R ^p3 and R ^p4 are preferably a hydrogen atom, a fluorine atom and a fluorinated alkyl group, more preferably a fluorine atom and a perfluoroalkyl group, and still more preferably a fluorine atom and a trifluoromethyl group.

Examples of the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by R ^p5 and R ^p6 include a fluorinated alkyl group having 1 to 20 carbon atoms. R ^p5 and R ^p6 are preferably a fluorine atom and a fluorinated alkyl group, more preferably a fluorine atom and a perfluoroalkyl group, still more preferably a fluorine atom and a trifluoromethyl group, and particularly preferably a fluorine atom.

The n ^p1, preferably an integer of 0 to 5, more preferably an integer of 0 to 3, more preferably an integer of 0 to 2, 0 and 1 are particularly preferred.

The n ^p2, preferably an integer of 0 to 5, more preferably an integer of 0 to 2, more preferably 0 and 1, 0 being particularly preferred.

As a minimum of ^np3 , 1 is preferable and 2 is more preferable. By setting n ^p3 to 1 or more, the strength of the acid generated from the compound (4-1) can be increased, and as a result, the LWR performance and the like of the radiation-sensitive resin composition can be further improved. The upper limit of n ^p3 is preferably 4, more preferably 3, and even more preferably 2.

The lower limit of n ^p1 + n ^p2 + n ^p3 is preferably 2 and more preferably 4. The upper limit of n ^p1 + n ^p2 + n ^p3 is preferably 20, and more preferably 10.

Examples of the monovalent radiation-sensitive onium cation represented by Z ⁺ include cations represented by the following formulas (Z-1) to (Z-3) (hereinafter referred to as “cations (Z-1) to (Z−)”. 3) ")) and the like.

In the formula (Z-1), R ^a1 , R ^a2 and R ^a3 each independently represent a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted aromatic group having 6 to 12 carbon atoms. family hydrocarbon group, two or more are combined with each other configured ring structure of either a -OSO ₂ -R ^P or _-SO 2 -R ^Q, or their groups. R ^P and R ^Q are each independently a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms, or a substituted or unsubstituted carbon. It is an aromatic hydrocarbon group of formula 6-12. k1, k2 and k3 are each independently an integer of 0 to 5. R ^a1 to R ^a3 and when ^{R P} and ^{R Q} are a plurality each of the plurality of ^R a1 ^{to R a3} and ^{R P} and ^{R Q} may be the same as or different from each other.

In the above formula (Z-2), R ^a4 is a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 8 carbon atoms. k4 is an integer of 0 to 7. If R ^a4 is plural, the plurality of R ^a4 may be the same or different, and plural R ^a4 may represent a constructed ring aligned with each other. R ^a5 is a substituted or unsubstituted alkyl group having 1 to 7 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 or 7 carbon atoms. k5 is an integer of 0-6. If R ^a5 is plural, the plurality of R ^a5 may be the same or different, and plural R ^a5 may represent a keyed configured ring structure. r is an integer of 0-3. R ^a6 is a single bond or a divalent organic group having 1 to 20 carbon atoms. t is an integer of 0-2.

In the above formula (Z-3), R ^a7 and R ^a8 are each independently a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms or a substituted or unsubstituted aromatic hydrocarbon having 6 to 12 carbon atoms. group, or an -OSO ₂ -R ^R or _-SO 2 -R ^S, or two or more are combined with each other configured ring of these groups. R ^R and R ^S are each independently a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms, or a substituted or unsubstituted carbon. It is an aromatic hydrocarbon group of formula 6-12. k6 and k7 are each independently an integer of 0 to 5. R ^{a7, R} a8, ^R when ^R and ^{R S} is plural respective plurality of ^{R a7,} R a8, ^{R R} and ^{R S} may be the same as or different from each other.

Examples of the alkyl group represented by R ^{a1 to} R ^a3 , R ^a4 , R ^a5 , R ^a7 and R ^a8 include linear alkyl groups such as a methyl group, an ethyl group, an n-propyl group, and an n-butyl group;
Examples thereof include branched alkyl groups such as i-propyl group, i-butyl group, sec-butyl group and t-butyl group.

Examples of the aromatic hydrocarbon group represented by R ^{a1 to} R ^a3 , R ^a4 and R ^a5 include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a mesityl group, and a naphthyl group;
Examples include aralkyl groups such as benzyl group and phenethyl group.

Examples of the aromatic hydrocarbon group represented by R ^a4 and R ^a5 include a phenyl group, a tolyl group, and a benzyl group.

Examples of the divalent organic group represented by R ^a6 include a group obtained by removing one hydrogen atom from the monovalent organic group represented by R ^{4 in} the above formula (a-3).

  Examples of the substituent for substituting the hydrogen atom of the alkyl group and aromatic hydrocarbon group include halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom, hydroxy group, carboxy group, cyano group, nitro group, alkoxy Group, alkoxycarbonyl group, alkoxycarbonyloxy group, acyl group, acyloxy group and the like. Among these, a halogen atom is preferable and a fluorine atom is more preferable.

R ^{a1 to} R ^a3 , R ^a4 , R ^a5 , R ^a7 and R ^a8 include an unsubstituted alkyl group, a fluorinated alkyl group, an unsubstituted monovalent aromatic hydrocarbon group, —OSO ₂ —R ″ and —SO ₂ —R ″ is preferable, a fluorinated alkyl group and an unsubstituted monovalent aromatic hydrocarbon group are more preferable, and a fluorinated alkyl group is further preferable. R ″ is an unsubstituted monovalent alicyclic hydrocarbon group or an unsubstituted monovalent aromatic hydrocarbon group.

  As k1, k2, and k3 in Formula (Z-1), integers of 0 to 2 are preferable, 0 and 1 are more preferable, and 0 is more preferable. As k4 in Formula (Z-2), an integer of 0 to 2 is preferable, 0 and 1 are more preferable, and 1 is more preferable. k5 is preferably an integer of 0 to 2, more preferably 0 and 1, and still more preferably 0. As r, 2 and 3 are preferable, and 2 is more preferable. As t, 0 and 1 are preferable, and 0 is more preferable. As k6 and k7 in Formula (Z-3), an integer of 0 to 2 is preferable, 0 and 1 are more preferable, and 0 is more preferable.

Among these, cation (Z-1) and cation (Z-2) are preferable as Z ⁺ , and triphenylsulfonium cation and 4-butoxynaphthalen-1-yltetrahydrothiophenium cation are more preferable.

  [B1a] Examples of the acid generator include compounds represented by the following formulas (4-1-1) to (4-1-16) (hereinafter, “compounds (4-1-1) to (4-1-1)”. 16) ")) and the like. [B1b] Examples of the acid generator include compounds represented by the following formulas (4-2-1) to (4-2-3) (hereinafter referred to as “compounds (4-2-1) to (4-2-2)”. 3) ")) and the like. [B1c] Examples of the acid generator include compounds represented by the following formula (4-3-1) and formula (4-3-2) (hereinafter referred to as “compound (4-3-1), (4-3)”. -2) "). [B1d] Examples of the acid generator include compounds represented by the following formula (4-4-1) and formula (4-4-2) (hereinafter referred to as “compound (4-4-1), (4-4)”. -2) ").

Formulas (4-1-1) to (4-1-16), (4-2-1) to (4-2-3), (4-3-1), (4-3-2), In (4-4-1) and (4-4-2), Z ⁺ is a monovalent onium cation.

  [B1] The acid generator is preferably an acid generator [B1a], and the compounds (4-1-1), (4-1-4), (4-1-12) and (4-1-16) In addition, a radiation-sensitive onium cation salt of 10-camphorsulfonic acid is more preferable.

  [B] The acid generator is also preferably a polymer in which the structure of an acid generator such as a polymer having a structural unit represented by the following formula (4-1 ′) is incorporated as a part of the polymer. .

In the above formula (4-1 ′), R ^p7 represents a hydrogen atom or a methyl group. L ⁴ is a single bond or —COO— or a divalent carbonyloxy hydrocarbon group. R ^p8 is a fluorinated alkanediyl group having 1 to 10 carbon atoms. Z ⁺ is synonymous with the above formula (4).

As R ^p7 , a hydrogen atom and a methyl group are preferable, and a methyl group is more preferable, from the viewpoint of copolymerization of the monomer that gives the structural unit represented by the above formula (4-1 ′).

L ⁴ is preferably a divalent carbonyloxy hydrocarbon group, preferably a carbonyloxyalkanediyl group, and more preferably a carbonyloxyethanediyl group.

R ^p8 is preferably a fluorinated alkanediyl group having 1 to 4 carbon atoms, more preferably a perfluoroalkanediyl group having 1 to 4 carbon atoms, and even more preferably a tetrafluoroethanediyl group.

  When the said radiation sensitive resin composition contains a [B1] acid generator, as a minimum of content of a [B1] acid generator, it is 0.1 mass part with respect to 100 mass parts of [A] polymers. Is preferred, 1 part by weight is more preferred, 3 parts by weight is further preferred, 5 parts by weight is particularly preferred, 7 parts by weight is even more preferred, and 10 parts by weight is most preferred. As an upper limit of the said content, 50 mass parts is preferable and 40 mass parts is more preferable.

  [B1] By making content of an acid generator into the said range, the sensitivity and developability of the said radiation sensitive resin composition improve more, As a result, LWR performance etc. can be improved further. In particular, when the exposure light is EUV or an electron beam, from the viewpoint of further increasing the sensitivity of the radiation sensitive resin composition, the lower limit of the content of [B] acid generator is 100 parts by mass of [A] polymer. On the other hand, 20 mass parts is preferable, 25 mass parts is more preferable, and 30 mass parts is further more preferable.

([B2] acid generator)
Examples of the acid generator [B] include photodisintegrable bases (hereinafter, also referred to as “[B2] acid generator”) that are exposed to light upon exposure to generate a weak acid. Examples of the weak acid that generates a photodegradable base include carboxylic acid and sulfonic acid. Of these, carboxylic acids are preferred. [B2] With the acid generator, the acid diffusion controllability is lowered in the exposed area by exposure and the acid diffusion controllability is maintained in the unexposed area. Therefore, the radiation sensitive resin composition contains the [B2] acid generator, whereby the contrast between the exposed portion and the unexposed portion is improved, and as a result, the LWR performance can be further improved.

  [B2] Examples of the acid generator include compounds represented by the following formula (5).

In the above formula (5), E ⁻ represents a monovalent carboxylate anion or a monovalent sulfonate anion. Z ⁺ is a monovalent radiation-sensitive onium cation.

E ^- The monovalent carboxylic acid anion represented by, for example, anionic, and the like represented by the following formula (5-a).

In the above formula (5-a), R ^A is a linear or branched alkyl group having 1 to 12 carbon atoms, a linear or branched fluorinated alkyl group having 1 to 12 carbon atoms, or 1 carbon atom. -12 linear or branched alkoxy groups. u is an integer of 0-2. When u is 2, two R ^A may be the same or different.

As R ^A in the above formula (5-a), a fluorinated alkyl group is preferable, and a trifluoromethyl group is more preferable.

  [B2] Examples of the acid generator include compounds represented by the following formulas.

  [B2] The acid generator is preferably a sulfonium salt, more preferably a triarylsulfonium salt, and even more preferably triphenylsulfonium salicylate and triphenylsulfonium 10-camphorsulfonate.

  When the said radiation sensitive resin composition contains a [B2] acid generator, as a minimum of content of a [B2] acid generator, it is 0.1 mass part with respect to 100 mass parts of [A] polymers. Is more preferable, 0.5 parts by mass is more preferable, 1 part by mass is further preferable, 2 parts by mass is particularly preferable, 3 parts by mass is further particularly preferable, and 5 parts by mass is most preferable. As an upper limit of the said content, 20 mass parts is preferable, 15 mass parts is more preferable, 10 mass parts is further more preferable, and 8 mass parts is especially preferable.

  The radiation-sensitive resin composition can contain one or more [B] acid generators. The radiation-sensitive resin composition preferably contains two or more [B] acid generators, and more preferably contains at least one [B1] acid generator and [B2] acid generator. . The said radiation sensitive resin composition can improve LWR performance more by containing 2 or more types of [B] acid generators.

  When the radiation sensitive resin composition contains both [B1] acid generator and [B2] acid generator as [B] acid generator, the lower limit of the content of [B2] acid generator is: [B1] With respect to 100 parts by mass of the acid generator, 5 parts by mass is preferable, 10 parts by mass is more preferable, 15 parts by mass is further preferable, and 20 parts by mass is particularly preferable. As an upper limit of the said content, 100 mass parts is preferable, 60 mass parts is more preferable, 40 mass parts is further more preferable, 30 mass parts is especially preferable. The radiation sensitive resin composition can further improve the LWR performance by setting the content of the [B2] acid generator to the [B1] acid generator within the above range.

<[C] Nitrogen-containing compound>
The said radiation sensitive resin composition may contain a [C] nitrogen-containing compound as needed. [C] The nitrogen-containing compound controls the diffusion phenomenon in the resist film of the acid generated from the [B] acid generator by exposure, and has an effect of suppressing an undesirable chemical reaction in the non-exposed region. Further, the storage stability of the radiation sensitive resin composition is improved, and the resolution as a resist is further improved. Furthermore, a change in the line width of the resist pattern due to fluctuations in the holding time from exposure to development processing can be suppressed, and a radiation-sensitive resin composition excellent in process stability can be obtained.

  [C] Examples of the nitrogen-containing compound include a compound represented by the following formula (6) (hereinafter, also referred to as “nitrogen-containing compound (I)”), a compound having two nitrogen atoms in the same molecule (hereinafter, “ Nitrogen-containing compound (II) ”, compounds having three nitrogen atoms (hereinafter also referred to as“ nitrogen-containing compound (III) ”), amide group-containing compounds, urea compounds, nitrogen-containing heterocyclic compounds, and the like. .

In the above formula (6), R ⁶¹ , R ⁶² and R ⁶³ are each independently a hydrogen atom, an optionally substituted linear, branched or cyclic alkyl group, aryl group or aralkyl group. .

  Examples of the nitrogen-containing compound (I) include monoalkylamines such as n-hexylamine; dialkylamines such as di-n-butylamine; trialkylamines such as triethylamine; aromatic amines such as aniline. It is done.

  Examples of the nitrogen-containing compound (II) include ethylenediamine, N, N, N ′, N′-tetramethylethylenediamine, and the like.

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

  Examples of the amide group-containing compound include formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methylpyrrolidone and the like. It is done.

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

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

  As the nitrogen-containing organic compound, a compound having an acid dissociable group can also be used. Examples of the nitrogen-containing organic compound having such an acid dissociable group include Nt-butoxycarbonylpiperidine, Nt-butoxycarbonylimidazole, Nt-butoxycarbonylbenzimidazole, Nt-butoxycarbonyl-2. -Phenylbenzimidazole, N- (t-butoxycarbonyl) di-n-octylamine, N- (t-butoxycarbonyl) diethanolamine, N- (t-butoxycarbonyl) dicyclohexylamine, N- (t-butoxycarbonyl) diphenylamine Nt-butoxycarbonyl-4-hydroxypiperidine, Nt-amyloxycarbonyl-4-hydroxypiperidine and the like.

  When the said radiation sensitive resin composition contains a [C] nitrogen-containing compound, as a minimum of content of [C] nitrogen-containing compound, it is 0.1 mass part with respect to 100 mass parts of [A] polymers. Is preferred, 0.3 parts by weight is more preferred, and 0.5 parts by weight is even more preferred. As an upper limit of the said content, 10 mass parts is preferable, 5 mass parts is more preferable, and 2 mass parts is further more preferable.

<[D] solvent>
The radiation-sensitive resin composition usually contains a [D] solvent. [D] The solvent is not particularly limited as long as it is a solvent capable of dissolving or dispersing at least the [A] polymer, the [B] acid generator, and the optionally contained [C] nitrogen-containing compound.

  [D] Examples of the solvent include alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, hydrocarbon solvents, and the like.

Examples of alcohol solvents include methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, n-pentanol, iso-pentanol, 2-methylbutanol, sec-pentanol, tert-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, 3-heptanol, n-octanol, 2-ethylhexanol , Sec-octanol, n-nonyl alcohol, 2,6-dimethyl-4-heptanol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec -Monoalcohol solvents such as heptadecyl alcohol, furfuryl alcohol, phenol, cyclohexanol, methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol, diacetone alcohol;
Ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol, 2 -Polyhydric alcohol solvents such as ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol;
Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethylbutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl Ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol Monomethyl ether, dipropylene glycol monoethyl ether, polyhydric alcohol partial ether solvents such as dipropylene glycol monopropyl ether.

Examples of ether solvents include dialkyl ether solvents such as diethyl ether, dipropyl ether, and dibutyl ether;
Cyclic ether solvents such as tetrahydrofuran and tetrahydropyran;
Aromatic ring-containing ether solvents such as diphenyl ether and anisole (methylphenyl ether) are exemplified.

Examples of the ketone solvent include acetone, butanone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, 2-heptanone (methyl-n-pentyl ketone), and ethyl-n-butyl ketone. Chain ketone solvents such as methyl-n-hexyl ketone, di-iso-butyl ketone and trimethylnonanone:
Cyclic ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone and methylcyclohexanone:
2,4-pentanedione, acetonylacetone, acetophenone and the like can be mentioned.

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

Examples of the ester solvent include methyl acetate, ethyl acetate, n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl acetate, sec-butyl acetate, n-pentyl acetate, i-pentyl acetate, sec -Acetate solvents such as pentyl, 3-methoxybutyl acetate, methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methylcyclohexyl acetate, n-nonyl acetate;
Ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol mono-n-butyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether Polyhydric alcohol partial ether acetate solvents such as acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate;
Carbonate solvents such as dimethyl carbonate and diethyl carbonate;
Lactic acid ester solvents such as methyl lactate, ethyl lactate, n-butyl lactate, and n-amyl lactate;
Diethyl acetate, methoxytriglycol acetate, ethyl propionate, n-butyl propionate, iso-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl acetoacetate, ethyl acetoacetate, diethyl malonate, phthalate Examples thereof include dimethyl acid and diethyl phthalate.

Examples of the hydrocarbon solvent include n-pentane, iso-pentane, n-hexane, iso-hexane, n-heptane, iso-heptane, 2,2,4-trimethylpentane, n-octane, iso-octane, and cyclohexane. , Aliphatic hydrocarbon solvents such as methylcyclohexane;
Fragrances such as benzene, toluene, xylene, mesitylene, ethylbenzene, trimethylbenzene, methylethylbenzene, n-propylbenzene, iso-propylbenzene, diethylbenzene, iso-butylbenzene, triethylbenzene, di-iso-propylbenzene and n-amylnaphthalene Group hydrocarbon solvents and the like.

  Of these, ester solvents are preferred, polyhydric alcohol partial ether acetate solvents and lactic acid ester solvents are more preferred, and propylene glycol monomethyl ether acetate and ethyl lactate are even more preferred. The radiation-sensitive resin composition may contain one or more [D] solvents.

<Other optional components>
The radiation-sensitive resin composition may contain other optional components in addition to the above [A] to [D]. Examples of the other optional components include a fluorine atom-containing polymer, a surfactant, an alicyclic skeleton-containing compound, and a sensitizer. Each of these other optional components may be used alone or in combination of two or more.

[Fluorine atom-containing polymer]
The fluorine atom-containing polymer is a polymer having a higher fluorine atom content than the [A] polymer. When the radiation-sensitive composition contains a fluorine atom-containing polymer, when the resist film is formed, the distribution is unevenly distributed near the resist film surface due to the oil-repellent characteristics of the fluorine atom-containing polymer in the resist film. It is possible to prevent the acid generator, the acid diffusion controller and the like from being eluted into the immersion medium during immersion exposure. Further, due to the water-repellent characteristics of this fluorine atom-containing polymer, the advancing contact angle between the resist film and the immersion medium can be controlled within a desired range, and the occurrence of bubble defects can be suppressed. Furthermore, the receding contact angle between the resist film and the immersion medium is increased, and high-speed scanning exposure is possible without leaving water droplets. Thus, the said radiation sensitive composition can form the resist film suitable for an immersion exposure method by further containing a fluorine atom containing polymer.

  As a minimum of content of a fluorine atom content polymer, 0.1 mass part is preferred to 100 mass parts of [A] polymer, 0.5 mass part is more preferred, and 1 mass part is still more preferred. As an upper limit of the said content, 20 mass parts is preferable, 15 mass parts is more preferable, and 10 mass parts is further more preferable.

[Surfactant]
Surfactants have the effect of improving coatability, striation, developability, and the like. Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol diacrylate. Nonionic surfactants such as stearate; commercially available products include KP341 (Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (above, Kyoeisha Chemical Co., Ltd.), F-top EF301, EF303, EF352 (above, Tochem Products), MegaFuck F171, F173 (above, DIC), Florard FC430, FC431 (above, Sumitomo 3M) Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (above, Asahi Glass Industrial Co., Ltd.) Can be mentioned. As an upper limit of content of surfactant, 2 mass parts is preferable with respect to 100 mass parts of [A] polymers.

[Alicyclic skeleton-containing compound]
The alicyclic skeleton-containing compound has an effect of improving dry etching resistance, pattern shape, adhesion to the substrate, and the like.

Examples of the alicyclic skeleton-containing compound include adamantane derivatives such as 1-adamantanecarboxylic acid, 2-adamantanone, and 1-adamantanecarboxylic acid t-butyl;
Deoxycholic acid esters such as t-butyl deoxycholate, t-butoxycarbonylmethyl deoxycholic acid, 2-ethoxyethyl deoxycholic acid;
Lithocholic acid esters such as t-butyl lithocholic acid, t-butoxycarbonylmethyl lithocholic acid, 2-ethoxyethyl lithocholic acid;
3- [2-Hydroxy-2,2-bis (trifluoromethyl) ethyl] tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodecane, 2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo [4.2.1.0 ^3,7 ] nonane, and the like. As an upper limit of content of an alicyclic frame | skeleton containing compound in the said radiation sensitive resin composition, 5 mass parts is preferable with respect to 100 mass parts of [A] polymers.

[Sensitizer]
A sensitizer exhibits the effect | action which increases the production amount of the acid from [B] acid generator etc., and there exists an effect which improves the "apparent sensitivity" of the said radiation sensitive resin composition.

  Examples of the sensitizer include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, phenothiazines and the like. As an upper limit of content of the sensitizer in the said radiation sensitive resin composition, 2 mass parts is preferable with respect to 100 mass parts of [A] polymers.

<Method for preparing radiation-sensitive resin composition>
In the radiation sensitive resin composition, for example, a [A] polymer, a [B] acid generator, a [C] nitrogen-containing compound contained as necessary, and a [D] solvent are mixed at a predetermined ratio. Can be prepared. The radiation-sensitive resin composition is preferably filtered after mixing with, for example, a filter having a pore size of about 0.2 μm. As a minimum of solid concentration of the radiation sensitive resin composition, 0.1 mass% is preferred, 0.5 mass% is more preferred, and 1 mass% is still more preferred. As an upper limit of the said solid content concentration, 50 mass% is preferable, 30 mass% is more preferable, and 10 mass% is further more preferable.

<Resist pattern formation method>
In the resist pattern forming method, a step of coating the radiation-sensitive resin composition on one surface side of a substrate (hereinafter also referred to as “coating step”) and a resist film obtained by the coating are exposed. A step (hereinafter also referred to as “exposure step”) and a step of developing the exposed resist film (hereinafter also referred to as “development step”).

  According to the resist pattern forming method, since the radiation sensitive resin composition described above is used, a resist pattern with high sensitivity, low LWR, and small film loss can be formed. Hereinafter, each step will be described.

[Resist film forming step]
In this step, the radiation sensitive resin composition is applied to one surface side of the substrate. Thereby, a resist film is formed. Examples of the substrate include conventionally known ones such as a silicon wafer, silicon dioxide, and a wafer coated with aluminum. Further, for example, an organic or inorganic antireflection film disclosed in Japanese Patent Publication No. 6-12452, Japanese Patent Application Laid-Open No. 59-93448, or the like may be formed on the substrate. Examples of the coating method include spin coating, spin coating, and roll coating. After coating, soft baking (SB) may be performed as needed to volatilize the solvent in the coating film. As a minimum of the temperature of SB, 60 degreeC is preferable and 80 degreeC is more preferable. As an upper limit of the said temperature, 140 degreeC is preferable and 120 degreeC is more preferable. The lower limit of the SB time is preferably 5 seconds, and more preferably 10 seconds. As a minimum of the above-mentioned time, 600 seconds are preferred and 300 seconds are more preferred. As a minimum of the average thickness of the resist film formed, 10 nm is preferable and 20 nm is more preferable. As an upper limit of the average thickness, 1,000 nm is preferable, and 500 nm is more preferable.

  When immersion exposure is performed and the radiation-sensitive resin composition does not contain a fluorine atom-containing polymer, the direct contact between the immersion liquid and the resist film is formed on the resist film formed above. In order to avoid this, an immersion protective film that is insoluble in the immersion liquid may be provided. As the immersion protective film, a solvent peeling type protective film that peels off with a solvent before the developing step (see JP 2006-227632 A), a developer peeling type protective film that peels off simultaneously with development in the developing step (International Publication No. 1). Any of 2005/069096 and International Publication No. 2006/035790 may be used. However, from the viewpoint of throughput, it is preferable to use a developer peeling type immersion protective film.

[Exposure process]
In this step, the resist film obtained by the above coating is exposed. This exposure may be performed through a photomask (in some cases, through an immersion medium such as water). As the exposure light, electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light (EUV), X-rays and γ rays; charged particle beams such as electron beams and α rays, depending on the line width of the target pattern. Etc. Among these, far ultraviolet rays, EUV, X-rays and electron beams are preferable, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), EUV, X-rays and electron beams are more preferable, EUV, X-rays And an electron beam are more preferable.

  When the exposure is performed by immersion exposure, examples of the immersion liquid to be used include water and a fluorine-based inert liquid. The immersion liquid is preferably a liquid that is transparent to the exposure wavelength and has a refractive index temperature coefficient that is as small as possible so as to minimize distortion of the optical image projected onto the film. In the case of excimer laser light (wavelength 193 nm), it is preferable to use water from the viewpoints of availability and easy handling in addition to the above-described viewpoints. When water is used, an additive that reduces the surface tension of water and increases the surface activity may be added in a small proportion. This additive is preferably one that does not dissolve the resist film on the wafer and can ignore the influence on the optical coating on the lower surface of the lens. The water used is preferably distilled water.

  After the above exposure, post exposure baking (PEB) is performed, and in the exposed portion of the resist film, the acid dissociable group of the [A] polymer or the like by the acid generated from the [B] acid generator or the like by the exposure It is preferable to promote dissociation. This PEB can increase the difference in solubility in the developer between the exposed portion and the unexposed portion. As a minimum of the temperature of PEB, 50 degreeC is preferable and 80 degreeC is more preferable. As an upper limit of the said temperature, 180 degreeC is preferable and 130 degreeC is more preferable. The lower limit of the PEB time is preferably 5 seconds, and more preferably 10 seconds. The upper limit of the time is preferably 600 seconds, and more preferably 300 seconds.

[Development process]
In this step, the exposed resist film is developed. Thereby, a predetermined resist pattern can be formed. After development, it is common to wash with water or a rinse solution such as alcohol and then dry. The development method in the development step may be alkali development or organic solvent development.

  In the case of alkaline development, examples of the developer used for development include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n- Propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, 1 , 5-diazabicyclo- [4.3.0] -5-nonene, and an alkaline aqueous solution in which at least one alkaline compound is dissolved. Among these, a TMAH aqueous solution is preferable, and a 2.38 mass% TMAH aqueous solution is more preferable.

  In the case of organic solvent development, examples of the developer include hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents, and other organic solvents, and solvents containing the above organic solvents. As said organic solvent, the 1 type (s) or 2 or more types of the solvent enumerated as the [E] solvent of the above-mentioned radiation sensitive resin composition are mentioned, for example. Among these, ester solvents and ketone solvents are preferable. As the ester solvent, an acetate solvent is preferable, and n-butyl acetate is more preferable. As the ketone solvent, a chain ketone is preferable, and 2-heptanone is more preferable. As a minimum of content of the organic solvent in a developing solution, 80 mass% is preferred, 90 mass% is more preferred, 95 mass% is still more preferred, and 99 mass% is especially preferred. Examples of components other than the organic solvent in the developer include water and silicone oil.

  As a developing method, for example, a method in which a substrate is immersed in a tank filled with a developer for a certain period of time (dip method), a method in which the developer is raised on the surface of the substrate by surface tension and is left stationary for a certain time (paddle method) ), A method of spraying the developer on the substrate surface (spray method), a method of continuously applying the developer while scanning the developer coating nozzle on the substrate rotating at a constant speed (dynamic dispensing method) Etc.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. The measuring method of each physical property is shown below.

[Weight average molecular weight (Mw), number average molecular weight (Mn) and dispersity (Mw / Mn)]
Mw and Mn use Tosoh's GPC columns (G2000HXL: 2, G3000HXL: 1, G4000HXL: 1), flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran, sample concentration: 1.0 mass% Sample injection amount: 100 μL, column temperature: 40 ° C., detector: measured by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard under the analysis conditions of a differential refractometer. The degree of dispersion (Mw / Mn) was calculated from the measurement results of Mw and Mn.

[ ¹³ C-NMR analysis]
Using a nuclear magnetic resonance apparatus (“JNM-ECX400” manufactured by JEOL Ltd.), heavy DMSO was used as a measurement solvent, and analysis for determining the content ratio (mol%) of each structural unit in each polymer was performed.

<[A] Synthesis of polymer>
The monomers used in the synthesis of each polymer are shown below. Compound (M-12) provides a structural unit containing the structure of [B] acid generator.

[Synthesis Example 1] (Synthesis of polymer (A-1))
Compound (M-1) 30.72 g (20 mol%), Compound (M-7) 16.26 g (20 mol%), Compound (M-9) 28.93 g (40 mol%) and Compound (M-10) ) 24.09 g (20 mol%), AIBN 4.4 g (6 mol% based on the total monomers) as a radical polymerization initiator, and 1.67 g of t-dodecyl mercaptan (2. 28 mol%) was dissolved in 200 g of propylene glycol monomethyl ether to prepare a monomer solution. Next, a 500 mL three-necked flask containing 100 g of propylene glycol monomethyl ether was purged with nitrogen for 30 minutes, and then heated to 85 ° C. with stirring, and the prepared monomer solution was added dropwise over 3 hours using a dropping funnel. The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, 200 g of ethyl acetate, 120 g of methanol, 32 g of water and 800 g of hexane were added to the polymerization reaction solution, mixed, and transferred to a 3 L separatory funnel. After standing for 30 minutes, the lower layer was recovered and solvent substitution was performed with propylene glycol monomethyl ether to obtain 200 g of a solution. Next, 250 g of methanol, 22 g of triethylamine and 4 g of water were added, and a hydrolysis reaction was performed for 8 hours while refluxing at the boiling point. After completion of the reaction, the solvent and triethylamine were distilled off under reduced pressure, and the resulting polymer was dissolved in propylene glycol monomethyl ether acetate to obtain a solution containing the polymer (A-1) having a solid content concentration of 25% by mass (244 g). Yield 61%). Mw of the polymer (A-1) was 6,300, and Mw / Mn was 1.45. As a result of ¹³ C-NMR analysis, the content ratio of each structural unit derived from (M-1), (M-7), p-hydroxystyrene and (M-10) was 19.5 mol% and 20. 5 mol%, 38.2 mol%, and 21.8 mol%.

[Synthesis Examples 2-5, 7, 8, and 10] (Synthesis of Polymers (A-2) to (A-5), (A-7), (A-8), and (A-10))
Polymers (A-2) to (A-5), (A-7), (A) are prepared by performing the same operations as in Synthesis Example 1 using monomers of the types and amounts shown in Table 1 below. -8) and (A-10) were synthesized.

[Synthesis Example 6] (Synthesis of Polymer (A-6))
Compound (M-3) 31.07 g (20 mol%), Compound (M-7) 15.54 g (20 mol%), Compound (M-8) 30.38 g (40 mol%) and Compound (M-10) 23.02 g (20 mol%), AIBN 4.2 g (6 mol% based on the total monomers) as a radical polymerization initiator, and 1.6 g of t-dodecyl mercaptan (2. 28 mol%) was dissolved in 200 g of propylene glycol monomethyl ether to prepare a monomer solution. Next, a 500 mL three-necked flask containing 100 g of propylene glycol monomethyl ether was purged with nitrogen for 30 minutes, and then heated to 85 ° C. with stirring, and the prepared monomer solution was added dropwise over 3 hours using a dropping funnel. The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, 200 g of ethyl acetate, 120 g of methanol, 32 g of water and 800 g of hexane were added to the polymerization reaction solution, mixed, and transferred to a 3 L separatory funnel. After standing for 30 minutes, the lower layer was recovered and dissolved in propylene glycol monomethyl ether acetate to obtain a solution containing the polymer (A-6) having a solid content concentration of 25% by mass (264 g, yield 66%). Mw of the polymer (A-6) was 6,170, and Mw / Mn was 1.42. As a result of ¹³ C-NMR analysis, the content ratio of each structural unit derived from (M-3), (M-7), (M-8) and (M-10) was 18.1 mol%, 21 0.7 mol%, 39.0 mol% and 21.2 mol%.

[Synthesis Example 9] (Synthesis of Polymer (A-9))
132.4 g (517 mmol) of the compound (M-5) as a cyclic olefin compound and 0.37 g (4.4 mmol) of 1-hexene as a molecular weight regulator were added to 180 g of toluene, and the mixture was heated and stirred at 80 ° C. To this toluene solution, 96.6 μg (0.15 μmol) of a compound represented by the following formula (1-1) as a catalyst (product name: “Umicore M51”) was added as a toluene solution (0.98 mL), and polymerization was performed. The reaction was started. One hour after the start of polymerization, 0.15 μmol of ethyl vinyl ether was added as a reaction terminator to stop the polymerization. After completion of the polymerization reaction, the polymerization reaction solution was added to 1,500 g of methanol to perform reprecipitation. The obtained powder was dissolved in propylene glycol monomethyl ether acetate to obtain a solution containing the polymer (A-9) having a solid concentration of 25% by mass (360 g, yield 90%). Mw of the polymer (A-9) was 21,000, and Mw / Mn was 1.23.

<Preparation of radiation-sensitive resin composition>
The [B] acid generator, the [C] solvent and the [D] nitrogen-containing compound used for the preparation of the radiation sensitive resin composition are shown below.

[[B] acid generator]
Each structural formula is shown below.
([B1] acid generator)
B1-1: Triphenylsulfonium 3- (piperidin-1-ylsulfonyl) -1,1,2,2,3,3-hexafluoropropane-1-sulfonate B1-2: Triphenylsulfonium adamantane-1-yloxy Carbonyl difluoromethanesulfonate B1-3: Triphenylsulfonium 6- (adamantan-1-ylcarbonyloxy) -1,1,2,2-tetrafluorobutane-1-sulfonate B1-4: Triphenylsulfonium 10-camphorsulfonate B1 -5: cyclohexylsulfonylphenyldiphenylsulfonium 5,6-di (cyclohexyloxycarbonyl) norbornane-2-sulfonate ([B2] acid generator)
B2-1: Triphenylsulfonium trifluoromethyl salicylate

[[C] Nitrogen-containing compound]
C-1: N- (n-undecan-1-ylcarbonyloxyethyl) morpholine

[[D] solvent]
D-1: Propylene glycol monomethyl ether acetate D-2: Ethyl lactate

[Example 1]
[A] (A-1) 100 parts by mass as a polymer, [B] (B1-1) 25 parts by mass and (B2-1) 6 parts by mass as an acid generator, and [D] (D -1) 4,493 mass parts and (D-2) 1,926 mass parts were mix | blended, and the radiation sensitive resin composition (J-1) was prepared.

[Examples 2 to 14 and Comparative Example 1]
Except having used each component of the kind and content shown in following Table 2, it operated similarly to Example 1 and each radiation sensitive resin composition (J-2)-(J-14) and (CJ- 1) was prepared. “-” In Table 2 indicates that the corresponding component was not used.

<Formation of resist pattern>
Using a spin coater (“CLEAN TRACK ACT8” manufactured by Tokyo Electron Ltd.) on the surface of an 8-inch silicon wafer, each radiation-sensitive resin composition shown in Table 3 below was applied, and SB was performed at 130 ° C. for 60 seconds. It was. Then, it cooled at 23 degreeC for 30 second, and formed the resist film with an average thickness of 50 nm. Next, the resist film was irradiated with an electron beam by using a simple electron beam drawing apparatus (“HL800D” manufactured by Hitachi, Ltd., output: 50 KeV, current density: 5.0 A / cm ² ). After the irradiation, PEB was performed for 60 seconds at the temperature shown in Table 3 below. Thereafter, development was performed at 23 ° C. for 30 seconds using a 2.38 mass% TMAH aqueous solution as an alkali developer, washed with water, and dried to form a positive resist pattern.

<Evaluation>
About each prepared said radiation sensitive resin composition and each formed said resist pattern, the sensitivity, LWR performance, and film | membrane reduction inhibitory property were evaluated in accordance with the following method. The evaluation results are shown in Table 3. “-” Of Comparative Example 1 in Table 3 indicates that it is a criterion for evaluation. A scanning electron microscope (Hitachi High-Technologies “S-9380”) was used for measuring the resist pattern.

[sensitivity]
The resist pattern was observed from above the pattern using the scanning electron microscope. The exposure amount at which the line width becomes a line and space pattern with a line width of 150 nm was taken as the optimum exposure amount, and the value of this optimum exposure amount was taken as the sensitivity (μC / cm ² ). The sensitivity indicates that the smaller the value, the better. When the sensitivity is 10% or more (sensitivity value is 90% or less) compared to that of Comparative Example 1, the sensitivity is “◯”, and the improvement is more than 0% and less than 10% (sensitivity is increased). When the value was greater than 90% and less than 100%, the evaluation was “Δ”, and when the sensitivity value was equal to or greater than that of Comparative Example 1, the evaluation was “x”.

[LWR performance]
The resist pattern was observed from above the pattern using the scanning electron microscope. A total of 50 line widths were measured at arbitrary points, and a 3-sigma value was obtained from the distribution of the measured values, and this was defined as LWR performance. The LWR performance indicates that the smaller the value, the better. When the value of LWR performance is 10% or more (LWR performance value is 90% or less) when the value of LWR performance is compared with the value of Comparative Example 1, “◯” and less than 10% (LWR) In the case where the performance value was more than 90%), it was evaluated as “Δ”.

[Membrane loss suppression]
Using a spin coater (“CLEAN TRACK ACT8” manufactured by Tokyo Electron Ltd.) on the surface of an 8-inch silicon wafer, each radiation-sensitive resin composition shown in Table 3 was applied, and PB was performed at 130 ° C. for 60 seconds. Then, it developed for 30 seconds at 23 degreeC using 2.38 mass% TMAH aqueous solution as an alkali developing solution, washed with water, and dried. After completion of the series of processes, the film thickness of the remaining resist film was measured, and the value obtained by subtracting the remaining film thickness from the initial film thickness was defined as the film reduction amount (nm), which was used as an index for film thickness reduction inhibition. For the film thickness measurement, an optical interference type film thickness measuring device (“Lambda Ace” manufactured by Dainippon Screen Mfg. Co., Ltd.) was used. It indicates that the smaller the value is, the better the film reduction suppression property is. The film loss inhibition property is evaluated as “◯” when an improvement of 10% or more is observed when the value of the film loss inhibition property is compared with the value of Comparative Example 1, and “△” when less than 10%. did.

  As is clear from the results in Table 3, according to the radiation-sensitive resin composition of the example, a resist pattern with high sensitivity, low LWR, and small film loss can be formed. Generally, according to electron beam exposure, it is known to show the same tendency as in the case of EUV exposure. Therefore, according to the radiation-sensitive resin composition of the example, even in the case of EUV exposure, It is presumed to be excellent in sensitivity, LWR performance and film loss suppression.

According to the radiation-sensitive resin composition and the resist pattern forming method of the present invention, a resist pattern with high sensitivity, low LWR, and small film loss can be formed. Therefore, the pattern forming method can be suitably used for a semiconductor device processing process and the like that are expected to be further miniaturized in the future.

Claims (12)

A first polymer having a carbon atom constituting a ring structure in the main chain and having an aromatic ring and an acid dissociable group in the side chain;
A radiation-sensitive resin composition comprising: a radiation-sensitive acid generator. The radiation-sensitive resin composition according to claim 1, wherein the first polymer has a structural unit represented by the following formula (1-1), (1-2), or (1-3).
(In Formula (1-1), R ¹ and R ² are each independently a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms. R ³ represents an aromatic ring and an acid-dissociable group. It represents an alicyclic structure having 4 to 20 ring members or an aliphatic heterocyclic structure having 4 to 20 ring members having an aromatic ring and an acid dissociable group.
(In formula (1-2), R ^{4 to} R ⁷ are each independently a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms. R ⁸ represents an aromatic ring and an acid-dissociable group. It represents an alicyclic structure having 4 to 20 ring members or an aliphatic heterocyclic structure having 4 to 20 ring members having an aromatic ring and an acid dissociable group.
In formula (1-3), R ⁹ and R ¹⁰ are each independently a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms. R ¹¹ represents an alicyclic structure having 4 to 20 ring members having an aromatic ring and an acid dissociable group, or an aliphatic heterocyclic structure having 4 to 20 ring members having an aromatic ring and an acid dissociable group. ) The radiation sensitive resin composition according to claim 2, wherein the structural unit represented by the formula (1-1) is represented by the following formula (1-1-1).
(In Formula (1-1-1), R ¹ and R ² have the same meanings as those in Formula (1-1). R ¹² and R ¹³ are each independently a hydrogen atom, a halogen atom, or a hydroxy group. Or a monovalent organic group having 1 to 20 carbon atoms, n is an integer of 0 to 4. When n is 2 or more, a plurality of R ¹² may be the same or different, and a plurality of R ¹³ 2 or more of one or more of R ¹² and one or more of R ¹³ may be combined with each other to form a ring member having 3 carbon atoms or carbon chains to which they are bonded. R ¹⁴ may be a divalent group containing an aromatic ring and an acid dissociable group. The feeling according to claim 3, wherein R ^{14 in the} formula (1-1-1) is represented by the following formula (2-1), (2-2), (2-3) or (2-4). Radiation resin composition.
(In Formula (2-1), R ¹⁵ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. Ar ¹ is a substituted or unsubstituted divalent aromatic group having 6 to 20 ring members. R ¹⁶ is a single bond or a divalent organic group having 1 to 20 carbon atoms, and R ^A is a monovalent acid-dissociable group.
In Formula (2-2), Ar ² is a substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 to 20 ring members. R ¹⁷ is a single bond or a divalent organic group having 1 to 20 carbon atoms. R ^B is a monovalent acid dissociable group.
In formula (2-3), R ¹⁸ is a tetravalent group constituting an alicyclic structure having 3 to 20 ring members together with a carbon atom. R ¹⁹ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. Ar ³ is a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 20 ring members. R ²⁰ is a single bond or a divalent organic group having 1 to 20 carbon atoms. R ^C is a monovalent acid dissociable group.
In formula (2-4), R ²¹ is a tetravalent group constituting an alicyclic structure having 3 to 20 ring members together with a carbon atom. Ar ⁴ is a substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 to 20 ring members. R ²² is a single bond or a divalent organic group having 1 to 20 carbon atoms. ^RD is a monovalent acid dissociable group. The radiation sensitive resin composition according to claim 2, wherein the structural unit represented by the formula (1-2) is represented by the following formula (1-2-1).
(In Formula (1-2-1), R ^{5 to} R ⁸ have the same meanings as in Formula (1-2) above. R ²³ is a divalent organic group containing an aromatic ring and an acid-dissociable group. M is an integer of 0 to 5) The radiation sensitive resin composition according to claim 2, wherein the structural unit represented by the formula (1-3) is represented by the following formula (1-3-1).

(In Formula (1-3-1), R ⁹ and R ¹⁰ have the same meanings as in Formula (1-3) above. R ²⁴ is a monovalent organic group containing an aromatic ring and an acid-dissociable group. K is an integer from 0 to 5.)   The radiation sensitive resin composition according to any one of claims 1 to 6, wherein the radiation sensitive acid generator has a ring structure having 6 or more ring members.   The radiation sensitive resin composition according to any one of claims 1 to 7, wherein the first polymer has a structural unit containing a phenolic hydroxyl group.   The radiation sensitive resin composition according to any one of claims 1 to 8, wherein the first polymer has a structural unit containing a fluorine atom.   The radiation sensitive resin composition of any one of Claims 1-9 containing the said radiation sensitive acid generator 2 or more types. Applying the radiation sensitive resin composition according to any one of claims 1 to 10 to one surface side of the substrate;
Exposing the resist film obtained by the coating,
And a step of developing the exposed resist film.   The resist pattern forming method according to claim 11, wherein the exposure light used in the exposure step is extreme ultraviolet rays, X-rays, or electron beams.