TWI833951B - Radiation-sensitive resin composition and resist pattern forming method - Google Patents

Abstract

The present invention is a radiation-sensitive resin composition and a resist pattern forming method using the same. The radiation-sensitive resin composition contains: a polymer having a first structural unit containing a phenolic hydroxyl group, and a resist pattern forming method containing the following formula ( 1) The second structural unit of the group represented and the third structural unit including the acid-dissociating group; the radiation-sensitive acid generator; and the compound are represented by the following formula (2).

Description

Radiation-sensitive resin composition and resist pattern forming method

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

The radiation-sensitive resin composition used in microfabrication using lithography is produced by far ultraviolet rays, extreme ultraviolet (EUV) such as ArF excimer laser light (wavelength 193nm) and KrF excimer laser light (wavelength 248nm). ) (wavelength 13.5nm) and other electromagnetic waves, electron beams and other charged particle beams and other radiation irradiation generate acid in the exposed part, and the exposed part and the unexposed part are dissolved in the developer through a chemical reaction using the acid as a catalyst The speed difference creates a resist pattern on the substrate.

The radiation-sensitive composition has good sensitivity to exposure light such as extreme ultraviolet rays and electron beams, and also has excellent line width roughness (LWR) performance that is required to exhibit line width uniformity.

In response to these requirements, the types, molecular structures, etc. of polymers or other components used in the radiation-sensitive resin composition have been studied, and their combinations have also been studied in detail (see Japanese Patent Laid-Open No. 2009-244805 Publication No., Japanese Patent Application Publication No. 2004-012510 and Japanese Patent Application Publication No. 2017-141373).

[Prior art documents]

[Patent Document]

[Patent Document 1] Japanese Patent Application Laid-Open No. 2009-244805

[Patent Document 2] Japanese Patent Application Publication No. 2004-012510

[Patent Document 3] Japanese Patent Application Laid-Open No. 2017-141373

As resist patterns are further miniaturized, slight fluctuations in exposure and development conditions have an increasing impact on the shape or defects of the resist patterns. There is also a demand for a radiation-sensitive resin composition with a wide process window (process latitude) that can absorb minute jitter caused by such process conditions. However, the previous radiation-sensitive resin composition cannot meet these requirements.

The present invention is based on the above situation, and its object is to provide a radiation-sensitive resin composition and a resist that can form a resist pattern that has good sensitivity to exposure light, excellent LWR performance, and a wide process window. Pattern formation method.

The invention made to solve the above problems is a radiation-sensitive resin composition containing a polymer (hereinafter also referred to as "[A] polymer") having a first structural unit including a phenolic hydroxyl group, A second structural unit of a group represented by the following formula (1) and a third structural unit including an acid-dissociating group; a radiation-sensitive acid generator (hereinafter, also referred to as "[B] acid generator"); and The compound (hereinafter, also referred to as "[C] compound") is represented by the following formula (2).

(In formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are each independently a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom or a carbon number of 1 to 10. fluorinated hydrocarbon group. Among them, at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ is a fluorine atom or a fluorinated hydrocarbon group. R ^A is a hydrogen atom or a monovalent fluorinated hydrocarbon group with 1 to 20 carbon atoms. Organic group. * represents a bonding site with a part other than the group represented by the formula (1) in the second structural unit)

(In formula (2), R ⁷ , R ⁸ and R ⁹ are each independently a hydrogen atom, a fluorine atom or a monovalent organic group having 1 to 40 carbon atoms, or two or more of these groups are combined with each other and These bonded carbon atoms together form part of a ring structure with ring members of 3 to 20. A ⁺ is a monovalent radioactive linium cation)

Another invention made to solve the above problem is a resist pattern forming method, which includes the step of directly or indirectly applying the radiation-sensitive resin composition on a substrate; The step of exposing the formed resist film; and the step of developing the resist film after the exposure step.

According to the radiation-sensitive resin composition and resist pattern forming method of the present invention, a resist pattern with good sensitivity to exposure light, excellent LWR performance, and a wide process window can be formed. Therefore, these can be suitably used in processing processes of semiconductor devices that are expected to be further miniaturized in the future.

<Radiosensitive resin composition>

This radiation-sensitive resin composition contains [A] polymer, [B] acid generator, and [C] compound. The radiation-sensitive resin composition may also contain a solvent (hereinafter, also referred to as "[D] organic solvent") as a preferred component, and may also contain other arbitrary components within a range that does not impair the effects of the present invention.

Since the radiation-sensitive resin composition contains [A] polymer, [B] acid generator, and [C] compound, it is possible to form a resist that has good sensitivity to exposure light, excellent LWR performance, and a wide process window. agent pattern. The reason why the radiation-sensitive resin composition exhibits the above-described effect due to the above-described structure is not necessarily clear, but it can be estimated as follows, for example. That is, since the [A] polymer contained in the radiation-sensitive resin composition has a first structural unit including a phenolic hydroxyl group and a second structural unit including a group represented by the formula (1), with respect to development The solubility of the liquid is improved. Furthermore, since the radiation-sensitive resin composition contains the [C] compound, the solubility with respect to the developer is further improved. As a result, it is considered that this radiation-sensitive resin composition can form a resist pattern with good sensitivity to exposure light, excellent LWR performance, and a wide process window.

In the following, each component contained in the radiation-sensitive resin composition will be analyzed. instruction.

<[A]polymer>

[A] The polymer has a first structural unit including a phenolic hydroxyl group (hereinafter, also referred to as "first structural unit"), and a second structural unit including a group represented by the formula (1) (hereinafter, also referred to as "first structural unit"). is the "second structural unit") and the third structural unit including an acid-dissociating group (hereinafter, also referred to as the "third structural unit"). [A] The polymer may have other structural units other than the first structural unit, the second structural unit and the third structural unit. [A] The polymer may have one type or two or more types of each structural unit.

Each structural unit of [A] polymer is demonstrated below.

[First structural unit]

The first structural unit is a structural unit containing a phenolic hydroxyl group. The so-called "phenolic hydroxyl group" is not limited to hydroxyl groups directly bonded to a benzene ring, but refers to all hydroxyl groups directly bonded to an aromatic ring. Since the polymer [A] has the first structural unit, the hydrophilicity of the resist film can be improved, the solubility in the developer can be appropriately adjusted, and the adhesion of the resist pattern to the substrate can be improved. In addition, when extreme ultraviolet rays or electron beams are used as the radiation irradiated in the exposure step in the resist pattern forming method described below, the sensitivity to the exposure light can be further improved.

Examples of the first structural unit include a structural unit represented by the following formula (3) and the like.

[Chemical 3]

In the formula (3), R ¹⁰ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ¹¹ is a single bond, -O-, -COO- or -CONH-. Ar is a group obtained by removing (p+q+1) hydrogen atoms on an aromatic ring from an aromatic hydrocarbon with 6 to 20 ring members. p is an integer from 0 to 10. When p is 1, R ¹² is a monovalent organic group having 1 to 20 carbon atoms or a halogen atom. When p is 2 or more, the plurality of R ¹² are the same as or different from each other, and are monovalent organic groups or halogen atoms with 1 to 20 carbon atoms, or two or more of the plurality of R ¹² are bonded to each other and combined with these The bonded carbon chains together form part of a ring structure with 4 to 20 ring members. q is an integer from 1 to 11. Among them, p+q is 11 or less.

R ¹⁰ is preferably a hydrogen atom or a methyl group from the viewpoint of providing copolymerizability of the monomer of the first structural unit.

When R ¹¹ is -COO-, the oxygen atom of the oxygen group is preferably bonded to Ar. When R ¹¹ is -CONH-, the nitrogen atom is preferably bonded to Ar. That is, if ** represents the bonding site with Ar, -COO- is preferably -COO-**, and -CONH- is preferably -CONH-**. R ¹¹ is preferably a single bond or -COO-, more preferably a single bond.

The so-called "number of ring members" refers to the number of atoms constituting the rings of the alicyclic structure, aromatic carbocyclic structure, aliphatic heterocyclic structure and aromatic heterocyclic structure. In the case of polycyclic rings, it refers to the number of atoms constituting the polycyclic ring. number of atoms.

Examples of aromatic hydrocarbons having 6 to 20 ring members that provide Ar include: benzene, Naphthalene, anthracene, phenanthrene, tetraphenyl, pyrene, etc. Ar is preferably benzene or naphthalene, more preferably benzene.

The so-called "organic group" refers to a group containing at least one carbon atom. The so-called "carbon number" refers to the number of carbon atoms constituting the group. Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ¹² include: a monovalent hydrocarbon group having 1 to 20 carbon atoms, and a group containing a bivalent heteroatom-containing group between the carbons of the hydrocarbon group ( α), a group (β) in which part or all of the hydrogen atoms of the hydrocarbon group and the group containing a divalent heteroatom-containing group are substituted with a monovalent heteroatom-containing group, and the Hydrocarbon group, group (α) or group (β) combined with a divalent heteroatom-containing group (γ), etc.

"Hydrocarbon group" includes chain hydrocarbon groups, alicyclic hydrocarbon groups and aromatic hydrocarbon groups. 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 only contains a chain structure, and includes both linear hydrocarbon groups and branched hydrocarbon groups. The term "alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic structure as a ring structure and does not include an aromatic ring structure, and includes both monocyclic alicyclic hydrocarbon groups and polycyclic alicyclic hydrocarbon groups. Among them, it is not necessary to include only an alicyclic structure, but may also include a chain structure in a part thereof. The term "aromatic hydrocarbon group" refers to a hydrocarbon group containing an aromatic ring structure as a ring structure. It does not necessarily have to contain only an aromatic ring structure, but may also contain a chain structure or an alicyclic structure in a part thereof.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include monovalent chain hydrocarbon groups having 1 to 20 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms, and monovalent aromatic hydrocarbon groups having 6 to 20 carbon atoms. Hydrocarbyl etc.

Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, and isopropyl; alkenyl groups such as vinyl, propenyl, and butenyl; Alkynyl groups such as ethynyl, propynyl, butynyl, etc.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include alicyclic saturated hydrocarbon groups such as cyclopentyl, cyclohexyl, norbornyl, adamantyl, tricyclodecyl, tetracyclododecyl and the like. , cyclopentenyl, cyclohexenyl, norbornenyl, tricyclodecene, tetracyclododecenyl and other alicyclic unsaturated hydrocarbon groups, etc.

Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include aryl groups such as phenyl, tolyl, xylyl, naphthyl, and anthryl, benzyl, phenethyl, naphthylmethyl, and anthracenyl. Methyl and other aralkyl groups, etc.

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

Examples of the divalent heteroatom-containing group include -O-, -CO-, -S-, -CS-, -NR'-, and a group obtained by combining two or more of these. R' is a hydrogen atom or a monovalent hydrocarbon group.

R ¹² is preferably a monovalent hydrocarbon group, more preferably an alkyl group.

Examples of a ring structure with 4 to 20 ring members in which two or more of the plurality of R ¹² are bonded to each other and formed together with the bonded carbon chains include: cyclopentane structure, cyclohexane structure, cyclohexane structure, Pentene structure, cyclohexene structure and other alicyclic structures, etc.

As p, 0 to 2 are preferred, 0 or 1 is more preferred, and 0 is still more preferred.

As q, 1 to 3 are preferred, and 1 or 2 is more preferred.

Examples of the first structural unit include the following formulas (3-1) to (3-12) Represented structural units, etc.

In the formula (3-1) to formula (3-12), R ¹⁰ has the same meaning as the formula (3).

As the first structural unit, it is preferably the formula (3-1) or formula (3-2) the structural unit represented.

The lower limit of the content ratio of the first structural unit in the polymer [A] is preferably 10 mol%, more preferably 15 mol%, and still more preferably 20 mol%, the best is 25 mol%. The upper limit of the content ratio is preferably 70 mol%, more preferably 65 mol%, further preferably 60 mol%, and particularly preferably 55 mol%. By setting the content ratio of the first structural unit to the above range, the sensitivity and LWR performance of the resist pattern formed from the radiation-sensitive resin composition to exposure light can be further improved, and the process window can be further expanded. .

[Second structural unit]

The second structural unit is a structural unit containing a group represented by the following formula (1).

In the formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are each independently a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom or a carbon number of 1 to 10. Monovalent fluorinated hydrocarbon group. Among them, at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ is a fluorine atom or a fluorinated hydrocarbon group. R ^A is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. * represents a bonding site with a portion other than the group represented by the formula (1) in the second structural unit.

Examples of the hydrocarbon group substituted with a fluorine atom among the monovalent fluorinated hydrocarbon groups having 1 to 10 carbon atoms represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ include those represented by the formula ( 3) R ¹² is the same as the hydrocarbon group exemplified. Specifically, examples of the monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms include a fluorinated alkyl group having 1 to 10 carbon atoms.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by ^RA include the same monovalent organic groups exemplified as R ¹² in the formula (3).

R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are preferably a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms, more preferably a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms. fluorinated alkyl group, more preferably a fluorine atom.

At least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ is a fluorine atom or a fluorinated hydrocarbon group, preferably one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ At least two of are fluorine atoms or fluorinated hydrocarbon groups, more preferably at least two of R ¹ , R ² and R ³ and at least two of R ⁴ , R ⁵ and R ⁶ are fluorine atoms or fluorinated hydrocarbon groups, More preferably, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are fluorine atoms or fluorinated hydrocarbon groups. Particularly preferably, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are fluorine. atom.

As ^RA , a hydrogen atom is preferred.

Examples of the second structural unit include structural units represented by the following formula (1-1) or formula (1-2).

[Chemical 6]

In the formula (1-1) and formula (1-2), R ^a1 is each independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. X is a group represented by the formula (1).

In the formula (1-1), L is a single bond or -COO-. R ^a2 is an (n+1)-valent organic group having 1 to 20 carbon atoms. n is an integer from 1 to 3. When n is 2 or more, the plurality of X's are the same or different from each other.

In the formula (1-2), R ^a3 is a divalent hydrocarbon group having 1 to 10 carbon atoms. R ^a4 is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^a5 and R ^a6 are each independently a hydrogen atom or a monovalent hydrocarbon group with a carbon number of 1 to 10, or a ring member of 3 to 20 composed of R ^a5 and R ^a6 bonded to each other and the bonded carbon atoms. part of the ring structure.

R ^a1 is preferably a hydrogen atom or a methyl group from the viewpoint of providing copolymerizability of the monomer of the second structural unit.

As L, -COO- is preferred. When L is -COO-, it is preferable that the oxygen atom of the oxygen group is bonded to R ^a2 . That is, if *** represents the bonding site with R ^a2 , -COO- is preferably -COO-***.

Examples of R ^a2 include a group obtained by removing n hydrogen atoms from the monovalent organic group exemplified as R ¹² of the formula (3). R ^a2 is preferably a hydrocarbon group, more preferably a chain hydrocarbon group or an alicyclic hydrocarbon group, further preferably a saturated chain hydrocarbon group or an alicyclic saturated hydrocarbon group, and particularly preferably an alicyclic saturated hydrocarbon group.

As n, 1 or 2 is preferred, and 1 is more preferred.

Examples of R ^a3 include a group obtained by removing one hydrogen atom from the monovalent hydrocarbon group exemplified as R ¹² of the formula (3). R ^a3 is preferably a chain hydrocarbon group, more preferably a saturated chain hydrocarbon group.

Examples of R ^a4 include the same hydrocarbon groups exemplified as R ¹² in the formula (3). As R ^a4 , a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms is preferred, and an aryl group is more preferred.

Examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by R ^a5 and R ^a6 include the same hydrocarbon groups as those exemplified as R ¹² of the formula (3). R ^a5 and R ^a6 are preferably hydrogen atoms.

Examples of the ring structure with 3 to 20 ring members in which R ^a5 and R ^a6 are bonded to each other and constituted together with the bonded carbon atoms include an alicyclic structure with 3 to 20 ring members.

Examples of the second structural unit represented by the formula (1-1) include structural units represented by the following formulas (1-1-1) to formula (1-1-3).

[Chemical 7]

In the formula (1-1-1) to formula (1-1-3), R ^a1 has the same meaning as the formula (1-1).

Examples of the structural unit represented by the formula (1-2) among the second structural units include the structural unit represented by the following formula (1-2-1).

In the formula (1-2-1), R ^a1 has the same meaning as the formula (1-2).

As the second structural unit, the structural unit represented by the above-mentioned formula (1-1-1) or formula (1-2-1) is preferred.

As the lower limit of the content ratio of the second structural unit in [A] polymer, It is preferably 3 mol%, more preferably 5 mol%, and still more preferably 10 mol% based on all the structural units constituting the polymer [A]. The upper limit of the content ratio is preferably 50 mol%, more preferably 45 mol%, and still more preferably 40 mol%. By setting the content ratio of the second structural unit to the above range, the sensitivity and LWR performance of the resist pattern formed from the radiation-sensitive resin composition to exposure light can be further improved, and the process window can be further expanded. .

[Third structural unit]

The third structural unit is a structural unit containing an acid-dissociating group. The "acid-dissociable group" refers to a group that substitutes a hydrogen atom such as a carboxyl group or a phenolic hydroxyl group and dissociates by the action of an acid. Since the polymer [A] contains the third structural unit having an acid-dissociating group, the acid-dissociating group is dissociated in the exposed part by the action of the acid generated from the acid generator [B] by exposure, and the acid-dissociating group is dissociated in the exposed part. A resist pattern can be formed by creating a difference in solubility to the developer between the unexposed portion and the unexposed portion.

Examples of the third structural unit include structural units represented by the following formula (4-1A), formula (4-1B), formula (4-2A), or formula (4-2B). Furthermore, ⁱⁿ the following formulas ⁽ 4-1A) to formula ( ^{4-2B )} , ^-CR (OR ^W ) is an acid-dissociating group.

[Chemical 9]

In the formula (4-1A), formula (4-1B), formula (4-1C), formula (4-2A) and formula (4-2B), R ^T is independently a hydrogen atom, a fluorine atom, Methyl or trifluoromethyl.

In the formula (4-1A) and formula (4-1B), R ^X is each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^Y and R ^Z are each independently a monovalent hydrocarbon group with 1 to 20 carbon atoms, or an alicyclic ring with 3 to 20 ring members formed by R ^Y and R ^Z combined with each other and the bonded carbon atoms. part of the structure.

In the formula (4-1C), R ^C is a hydrogen atom. R ^D and R ^E are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. ^RF is a divalent hydrocarbon group with 1 to 20 carbon atoms forming an unsaturated alicyclic structure with 4 to 20 ring members together with the carbon atoms to which R ^C , ^RD and ^RE are respectively bonded.

In the formula (4-2A) and formula (4-2B), R ^U and R ^V are each independently a hydrogen atom or a monovalent hydrocarbon group with a carbon number of 1 to 20, and R ^W is each independently a hydrogen atom or a monovalent hydrocarbon group with a carbon number of 1 to 20. A monovalent hydrocarbon group, or a part of an alicyclic structure with 3 to 20 ring members formed by R ^U and R ^V bonded to each other and together with the bonded carbon atoms, or R ^U and R ^W bonded to each other and It is part of an aliphatic heterocyclic structure with 5 to 20 ring members formed together with the carbon atom to which R ^U is bonded and the oxygen atom to which R ^W is bonded.

R ^T is preferably a hydrogen atom or a methyl group from the viewpoint of providing copolymerizability of the monomer of the third structural unit.

Examples ^{of the monovalent} hydrocarbon group having ^{1 to 20 carbon} atoms represented by ^{R 12.} The hydrocarbon groups exemplified are the same groups.

Examples of the divalent hydrocarbon group having 1 to 20 carbon atoms represented by ^RF include a group obtained by removing one hydrogen atom from the monovalent hydrocarbon group exemplified as R ¹² of the formula (3).

Examples of an alicyclic structure with 3 to 20 ring members in which R ^Y and R ^Z or R ^U and R ^V are bonded to each other and formed together with the bonded carbon atoms include: cyclopropane structure and cyclobutane structure. , cyclopentane structure, cyclohexane structure and other single-ring saturated alicyclic structures, norbornane structure, adamantane structure, tricyclic decane structure, tetracyclododecane structure and other polycyclic saturated alicyclic structures, rings Propylene structure, cyclobutene structure, cyclopentene structure, cyclohexene structure and other monocyclic unsaturated alicyclic structures, norbornene structure, tricyclic decene structure, tetracyclododecene structure and other polycyclic unsaturated structures Alicyclic structure, etc.

As an aliphatic heterocyclic structure with 5 to 20 ring members, R ^U and R ^W are bonded to each other and formed together with the carbon atom to which R ^U is bonded and the oxygen atom to which R ^W is bonded. Examples include: oxygen heterocyclic ring Butane structure, oxolane structure, oxane structure and other saturated oxygen-containing heterocyclic structures, oxetene structure, oxolane structure, oxane structure and other unsaturated oxygen-containing heterocyclic structures Heterocyclic structure, etc.

Examples of the unsaturated alicyclic structure with 4 to 20 ring members formed by the carbon atoms to which R ^F and R ^C , R ^D and ^RE are bonded together include: cyclobutene structure, cyclopentene structure, ring Unsaturated alicyclic structures such as hexene structure and norbornene structure.

As ^R

R ^Y and R ^Z are preferably a hydrocarbon group, more preferably a chain hydrocarbon group or an alicyclic hydrocarbon group, and further preferably an alkyl group or an alicyclic saturated hydrocarbon group.

R ^U is preferably a hydrogen atom or a hydrocarbon group, more preferably a hydrogen atom.

As ^RV and R ^W , a hydrocarbon group is preferred, and a chain hydrocarbon group is more preferred.

As the third structural unit, the structural unit represented by the above-mentioned formula (4-1A) is preferred.

The lower limit of the content ratio of the third structural unit in the polymer [A] is preferably 5 mol%, more preferably 10 mol%, and still more preferably 15 mol%. The upper limit of the content ratio is preferably 80 mol%, more preferably 70 mol%, and still more preferably 60 mol%. By setting the content ratio of the third structural unit within the above range, it is possible to further improve the sensitivity of the radiation. The sensitivity and LWR performance of the resist pattern formed by the linear resin composition relative to the exposure light can further expand the process window.

[Other structural units]

Examples of other structural units include structural units containing a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination of these structures. Structural units other than the second structural unit containing an alcoholic hydroxyl group are derived from Structural units of benzyl (meth)acrylate, etc. By having [A] polymer further having these other structural units, the solubility to the developer can be adjusted more appropriately. As a result, the resist pattern formed from the radiation-sensitive resin composition can be further improved. The sensitivity and LWR performance relative to the exposure light can further expand the process window. In addition, the adhesion between the resist pattern and the substrate can be further improved.

Examples of the structural unit including a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination of these structures include structural units represented by the following formulas.

[Chemical 10]

[Chemical 13]

In the formula, R ^L1 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

As the structural unit containing a lactone structure, a cyclic carbonate structure, a sultone structure or a combination of these structures, a structural unit containing a lactone structure is preferred, and a structural unit containing a norbornane lactone structure is more preferred. , and more preferably, a structural unit derived from norbornane lactone-based (meth)acrylate.

Examples of the structural unit containing an alcoholic hydroxyl group other than the second structural unit include a structural unit represented by the following formula.

In the formula, R ^L2 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

When [A] polymer has other structural units, the lower limit of the content ratio of other structural units is preferably 1 mol%, more preferably 5 mol% based on all the structural units in [A] polymer. Ear%. The upper limit of the content ratio is preferably 30 mol%, more preferably 20 mol%.

As [A] polymer by gel permeation chromatography (Gel Permeation The lower limit of the polystyrene-converted weight average molecular weight (Mw) obtained by Chromatography (GPC) is preferably 2,000, more preferably 3,000, further preferably 4,000, and particularly preferably 5,000. The upper limit of Mw is preferably 11,000, more preferably 10,000, further preferably 9,000, and particularly preferably 8,000. By setting the Mw of the polymer [A] to the above range, the coating properties of the radiation-sensitive resin composition can be improved. As a result, the resist formed from the radiation-sensitive resin composition can be further improved. The sensitivity of the pattern to the exposure light and LWR performance can further expand the process window.

The upper limit of the ratio (Mw/Mn) of the Mw obtained by GPC to the polystyrene-reduced number average molecular weight (Mn) of the polymer [A] is preferably 2.50, more preferably 2.00, and still more preferably 1.75 . The lower limit of the ratio is usually 1.00, preferably 1.10, more preferably 1.20. By setting the Mw/Mn of the polymer [A] to the above range, the coating properties of the radiation-sensitive resin composition can be further improved.

The Mw and Mn of the polymer in this specification are values measured by gel permeation chromatography (GPC) under the following conditions.

GPC columns: two "G2000HXL", one "G3000HXL" and one "G4000HXL" from Tosoh Co., Ltd.

Dissolution solvent: tetrahydrofuran

Flow: 1.0mL/min

Sample concentration: 1.0 mass%

Sample injection volume: 100μL

Tube string temperature: 40℃

Detector: Differential Refractometer

Standard material: monodisperse polystyrene

The lower limit of the content ratio of [A] polymer in the radiation-sensitive resin composition is preferably 50 mass %, more preferably 60 mass %, and still more preferably 50 mass % with respect to all components except [D] organic solvent. 70% by mass, preferably 80% by mass.

[A] The polymer can be synthesized, for example, by polymerizing monomers providing each structural unit using a known method.

<[B]Acid generator>

[B] An acid generator is a substance that generates acid by irradiation with radiation. Examples of radiation include electromagnetic waves such as visible rays, ultraviolet rays, far ultraviolet rays, extreme ultraviolet rays (EUV), X-rays, and gamma rays, and charged particle beams such as electron beams and alpha rays. The acid-dissociable group contained in the third structural unit of the [A] polymer is dissociated using the acid generated from the [B] acid generator by irradiation (exposure) of radiation to generate a carboxyl group, and the carboxyl group is generated in the exposed portion The difference in the solubility of the [A] polymer to the developer between the unexposed portion and the unexposed portion allows a resist pattern to be formed. Examples of the containing form of the [B] acid generator in the radiation-sensitive resin composition include: a form of a low molecular compound (hereinafter also referred to as "[B] acid generator"), [A] polymer part of it, or both of them.

The lower limit of the temperature at which an acid dissociates an acid-dissociating group is preferably 80°C, more preferably 90°C, and even more preferably 100°C. The upper limit of the temperature is preferably 130°C, more preferably 120°C, and even more preferably 110°C. The lower limit of the time for the acid to dissociate the acid-dissociating group is preferably 10 seconds, more preferably 1 minute. The upper limit of the time is preferably 10 minutes, more preferably 2 minutes.

Examples of the acid generated from the acid generator [B] include sulfonic acid, phenimidic acid, and the like.

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

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

Specific examples of [B] the acid generator include compounds described in paragraphs [0080] to [0113] of Japanese Patent Application Laid-Open No. 2009-134088, and the like.

Examples of the [B] acid generator that generates sulfonic acid upon irradiation of radiation include a compound represented by the following formula (5) (hereinafter also referred to as "compound (5)"). It is considered that the [B] acid generator having the following structure utilizes the interaction with the [A] polymer to shorten the diffusion length of the generated acid in the resist film more appropriately. As a result, it is possible to Further improving the sensitivity and LWR performance of the resist pattern formed by the radiation-sensitive resin composition with respect to exposure light can further expand the process window.

In the formula (5), R ^p1 is a monovalent group containing a ring structure with 5 or more ring members. R ^p2 is a bivalent 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 from 0 to 10. n ^p2 is an integer from 0 to 10. n ^p3 is an integer from 0 to 10. Among them, n ^p1 +n ^p2 +n ^p3 is 1 or more and 30 or less. When n ^p1 is 2 or more, a plurality of R ^p2 are the same as or different from each other. When n ^p2 is 2 or more, a plurality of R ^p3 are the same as or different from each other, and a plurality of R ^p4 are the same as or different from each other. When n ^p3 is 2 or more, a plurality of R ^p5 are the same as or different from each other, and a plurality of R ^p6 are the same as or different from each other. T ⁺ is a monovalent radioactive linium cation.

Examples of the monovalent group containing a ring structure with 5 or more ring members represented by R ^p1 include a monovalent group containing an alicyclic structure with 5 or more ring members, and an aliphatic heterocyclic ring with 5 or more ring members. A monovalent group of the structure, a monovalent group including an aromatic carbocyclic structure with 5 or more ring members, a monovalent group including an aromatic heterocyclic structure with 5 or more ring members, etc.

Examples of the alicyclic structure having 5 or more ring members include a cyclopentane structure, a cyclohexane structure, a cycloheptane structure, a cyclooctane structure, a cyclononane structure, a cyclodecane structure, and a cyclododecane structure. Monocyclic saturated alicyclic structures such as cyclopentene structure, cyclohexene structure, cycloheptene structure, cyclooctene structure, cyclodecene structure and other monocyclic unsaturated alicyclic structures, norbornane structure, adamantane Structure, tricyclic decane structure, tetracyclododecane structure and other polycyclic saturated alicyclic structures, norbornene structure, tricyclic decene structure and other polycyclic unsaturated alicyclic structures, etc.

Examples of aliphatic heterocyclic structures with 5 or more ring members include: hexane Lactone structure, norbornane lactone structure, lactone structure, hexane sultone structure, norbornane sultone structure, etc. sultone structure, oxepane structure, oxanorbornane structure, etc. Oxygen-containing Atomic heterocyclic structures, azacyclohexane structures, diazabicyclooctane structures and other nitrogen-containing heterocyclic structures, thiane structures, thianorbornane structures and other sulfur-atom-containing heterocyclic structures wait.

Examples of the aromatic carbon ring structure having 5 or more ring members include a benzene structure, a naphthalene structure, a phenanthrene structure, an anthracene structure, and the like.

Examples of the aromatic heterocyclic structure having 5 or more ring members include oxygen atom-containing heterocyclic structures such as furan structure, pyran structure, benzofuran structure, and benzopyran structure, pyridine structure, pyrimidine structure, and indole structure. Indole structure and other heterocyclic structures containing nitrogen atoms.

The lower limit of the number of ring members in the ring structure of R ^p1 is preferably 6, more preferably 8, further preferably 9, and particularly preferably 10. The upper limit of the number of ring members is preferably 15, more preferably 14, further preferably 13, and particularly preferably 12. By setting the number of ring members in the above range, the diffusion length of the acid can be shortened more appropriately. As a result, the resistance of the resist pattern formed from the radiation-sensitive resin composition to exposure can be further improved. The light sensitivity and LWR performance can further expand the process window.

Some or all of the hydrogen atoms in the ring structure of R ^p1 may be substituted with substituents. Examples of the substituent include: halogen atoms such as fluorine atom, chlorine atom, bromine atom, and iodine atom; hydroxyl group, carboxyl group, cyano group, nitro group, alkoxy group, alkoxycarbonyl group, and alkoxycarbonyloxy group , acyl group, acyloxy group, etc. Among these, hydroxyl group is preferred.

R ^p1 is preferably a monovalent group containing an alicyclic structure with 5 or more ring members or a monovalent group containing an aliphatic heterocyclic structure with 5 or more ring members, and more preferably a saturated alicyclic structure containing multiple rings. A monovalent group, a monovalent group containing a heterocyclic structure containing an oxygen atom, or a monovalent group containing a heterocyclic structure containing a nitrogen atom, and more preferably an adamantyl group, a norbornane sultone-based group or a nitrogen heterocyclic ring Hexane-based.

Examples of the divalent linking group represented by R ^p2 include a carbonyl group, an ether group, a carbonyloxy group, a thioether group, a thiocarbonyl group, a sulfonyl group, a divalent hydrocarbon group, and the like. Among these, a carbonyloxy group, a sulfonyl group, an alkanediyl group or a divalent alicyclic saturated hydrocarbon group is preferred, and a carbonyloxy group or a sulfonyl group is more 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 or a fluorinated alkyl group, more preferably a fluorine atom or a perfluoroalkyl group, and still more preferably a fluorine atom or 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 or a fluorinated alkyl group, more preferably a fluorine atom or a perfluoroalkyl group, further preferably a fluorine atom or a trifluoromethyl group, and particularly preferably a fluorine atom.

As n ^p1 , 0 to 5 is preferred, 0 to 2 is more preferred, and 0 or 1 is even more preferred.

As n ^p2 , 0 to 5 is preferred, 0 to 2 is more preferred, and 0 or 1 is even more preferred.

As the lower limit of n ^p3 , 1 is preferred, and 2 is more preferred. By setting n ^p3 to 1 or more, the strength of the acid generated from the compound (5) can be increased. As a result, the resistance of the resist pattern formed from the radiation-sensitive resin composition to exposure can be further improved. The light sensitivity and LWR performance can further expand the process window. The upper limit of n ^p3 is preferably 4, more preferably 3, and still more preferably 2.

As the lower limit of n ^p1 +n ^p2 +n ^p3 , 2 is preferred, and 4 is more preferred. 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 T ⁺ include: a cation represented by the following formula (ra) (hereinafter also referred to as "cation (ra)"), a cation represented by the following formula (rb) (hereinafter, also referred to as "cation (rb)"), a cation represented by the following formula (rc) (hereinafter, also referred to as "cation (rc)"), etc.

In the formula (ra), R ^B3 and R ^B4 are each independently a monovalent organic group having 1 to 20 carbon atoms. b3 is an integer from 0 to 11. When b3 is 1, R ^B5 is a monovalent organic group with 1 to 20 carbon atoms, a hydroxyl group, a nitro group or a halogen atom. When b3 is 2 or more, multiple R ^B5 are the same or different from each other, and are monovalent organic groups with 1 to 20 carbon atoms, hydroxyl groups, nitro groups or halogen atoms, or represent that these groups are combined with each other and with these groups. The bonded carbon chains together form part of a ring structure with 4 to 20 ring members. _nbb is an integer from 0 to 3.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by ^RB3 , ^RB4 , and ^RB5 include the same organic groups as those exemplified as ^R12 of the formula (3).

R ^B3 and R ^B4 are preferably a monovalent unsubstituted hydrocarbon group having 1 to 20 carbon atoms or a hydrocarbon group in which a hydrogen atom is substituted with a substituent, and more preferably a monovalent unsubstituted hydrocarbon group having 6 to 18 carbon atoms. A substituted aromatic hydrocarbon group or an aromatic hydrocarbon group in which a hydrogen atom is substituted with a substituent is more preferably a substituted or unsubstituted phenyl group, and particularly preferably an unsubstituted phenyl group.

The substituent that can replace the hydrogen atom of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented as R ^B3 and R ^B4 is preferably a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. Hydrocarbyl, -OSO ₂ -R ^k , -SO ₂ -R ^k , -OR ^k , -COOR ^k , -O-CO-R ^k , -OR ^kk -COOR ^k , -R ^kk -CO-R ^k or -SR ^k . R ^k is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ^kk is a single bond or a divalent hydrocarbon group with 1 to 10 carbon atoms.

R ^B5 is preferably a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, -OSO ₂ -R ^k , -SO ₂ -R ^k , -OR ^k , -COOR ^k , -O-CO -R ^k , -OR ^kk -COOR ^k , -R ^kk -CO-R ^k or -SR ^k . R ^k is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ^kk is a single bond or a divalent hydrocarbon group with 1 to 10 carbon atoms.

In the formula (rb), b4 is an integer from 0 to 9. When b4 is 1, R ^B6 is a monovalent organic group with 1 to 20 carbon atoms, a hydroxyl group, a nitro group or a halogen atom. When b4 is 2 or more, multiple R ^B6 are the same or different from each other, and are monovalent organic groups with 1 to 20 carbon atoms, hydroxyl groups, nitro groups or halogen atoms, or represent that these groups are combined with each other and with these groups. The bonded carbon chains together form part of a ring structure with 4 to 20 ring members. b5 is an integer from 0 to 10. When b5 is 1, R ^B7 is a monovalent organic group with 1 to 20 carbon atoms, a hydroxyl group, a nitro group or a halogen atom. When b5 is 2 or more, multiple R ^B7 are the same as or different from each other, and are monovalent organic groups with 1 to 20 carbon atoms, hydroxyl groups, nitro groups or halogen atoms, or represent that these groups are combined with each other and with these groups. The bonded carbon atoms or carbon chains together form part of a ring structure with 3 to 20 ring members. n _b2 is an integer from 0 to 3. R ^B8 is a single bond or a divalent organic group with 1 to 20 carbon atoms. n _b1 is an integer from 0 to 2.

The ^RB6 and ^RB7 are preferably substituted or unsubstituted monovalent hydrocarbon groups having 1 to 20 carbon atoms, -OR ^k , -COOR ^k , -O-CO-R ^k , -OR ^kk -COOR ^k or -R ^kk -CO-R ^k . R ^k is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ^kk is a single bond or a divalent hydrocarbon group with 1 to 10 carbon atoms.

In the formula (rc), b6 is an integer from 0 to 5. When b6 is 1, R ^B9 is a monovalent organic group with 1 to 20 carbon atoms, a hydroxyl group, a nitro group or a halogen atom. When b6 is 2 or more, multiple R ^B9 are the same or different from each other, and are monovalent organic groups with 1 to 20 carbon atoms, hydroxyl groups, nitro groups or halogen atoms, or represent that these groups are combined with each other and with these groups. The bonded carbon chains together form part of a ring structure with 4 to 20 ring members. b7 is an integer from 0 to 5. When b7 is 1, R ^B10 is a monovalent organic group with 1 to 20 carbon atoms, a hydroxyl group, a nitro group or a halogen atom. When b7 is 2 or more, the plurality of R ^B10 are the same as or different from each other, and are monovalent organic groups with 1 to 20 carbon atoms, hydroxyl, nitro or halogen atoms, or these groups are combined with each other and with these groups. The bonded carbon chains together form part of a ring structure with 4 to 20 ring members.

As the ^RB9 and ^RB10 , preferred are substituted or unsubstituted monovalent hydrocarbon groups having 1 to 20 carbon atoms, -OSO ₂ -R ^k , -SO ₂ -R ^k , -OR ^k , -COOR ^k , -O-CO-R ^k , -OR ^kk -COOR ^k , -R ^kk -CO-R ^k , -SR ^k or a ring structure formed by two or more of these groups combined with each other. R ^k is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ^kk is a single bond or a divalent hydrocarbon group with 1 to 10 carbon atoms.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by ^RB5 , ^RB6 , ^RB7 , ^RB9 , and ^RB10 include linear alkyl groups such as methyl, ethyl, n-propyl, and n-butyl. branched alkyl groups such as isopropyl, isobutyl, 2nd butyl, 3rd butyl, phenyl, tolyl, xylyl, mesityl, naphthyl and other aryl groups, benzyl, benzene Ethyl and other aralkyl groups, etc.

Examples of the divalent organic group represented by ^RB8 include monovalent organic groups having 1 to 20 carbon atoms exemplified as ^RB3 , ^RB4 , and ^RB5 of the formula (ra) by removing one hydrogen atom. The base et al.

Examples of the substituent that can replace the hydrogen atom of the hydrocarbon group represented by ^RB5 , ^RB6 , ^RB7 , ^RB9 , and ^RB10 include halogen atoms such as fluorine atom, chlorine atom, bromine atom, and iodine atom. , hydroxyl, carboxyl, cyano, nitro, alkoxy, alkoxycarbonyl, alkoxycarbonyloxy, acyl, acyloxy, etc. Among these, a halogen atom is preferred, and a fluorine atom is more preferred.

As ^RB5 , ^RB6 , ^RB7 , ^RB9 , and ^RB10 , preferred are unsubstituted linear or branched monovalent alkyl groups, monovalent fluorinated alkyl groups, and unsubstituted monovalent aromatic groups. The hydrocarbon group, -OSO ₂ -R ^k or -SO ₂ -R ^k , is more preferably a fluorinated alkyl group or an unsubstituted monovalent aromatic hydrocarbon group, and further preferably is a fluorinated alkyl group.

As b3 in the formula (ra), 0 to 2 are preferred, 0 or 1 is more preferred, and 0 is still more preferred. As n _bb , 0 or 1 is preferred, and 0 is more preferred. As b4 in the formula (rb), 0 to 2 are preferred, 0 or 1 is more preferred, and 0 is still more preferred. As b5, 0 to 2 are preferred, 0 or 1 is more preferred, and 0 is more preferred. As n _b2 , 2 or 3 is preferred, and 2 is more preferred. As n _b1 , 0 or 1 is preferred, and 0 is more preferred. As b6 and b7 in the formula (rc), 0 to 2 are preferred, 0 or 1 is more preferred, and 0 is still more preferred.

Among these, T ⁺ is preferably a cation (ra), and more preferably a triphenylsulfonium cation.

Regarding [B] acid generator, examples of the acid generator that generates sulfonic acid include compounds represented by the following formula (5-1) to formula (5-5) (hereinafter also referred to as "compound (5- 1)~Compound (5-5)"), etc.

[Chemical 17]

In the formulas (5-1) to (5-5), T ⁺ is a monovalent radioactive linium cation.

When [B] acid generator is [B] acid generator, the lower limit of the content of [B] acid generator in the radiation-sensitive resin composition is, relative to 100 parts by mass of [A] polymer, Preferably it is 0.1 part by mass, more preferably 1 part by mass, and still more preferably 5 parts by mass. The upper limit of the content is preferably 70 parts by mass, more preferably 50 parts by mass, further preferably 40 parts by mass, and particularly preferably 30 parts by mass. By setting the content of [B] acid generator to the above range, the sensitivity and LWR performance of the resist pattern formed from the radiation-sensitive resin composition to exposure light can be further improved, and the process window can be increased. Expand further.

<[C]Compound>

[C] The compound is a compound represented by the following formula (2). [C] Compound as acid Diffusion control agents come into play. The acid diffusion control agent exerts an effect of controlling the diffusion phenomenon of acid generated from the [B] acid generator or the like by exposure in the resist film and controlling undesirable chemical reactions in the non-exposed area. By containing the [C] compound in the radiation-sensitive resin composition, a resist pattern with good sensitivity to exposure light, excellent LWR performance, and a wide process window can be formed.

In the formula (2), R ⁷ , R ⁸ and R ⁹ are each independently a hydrogen atom, a fluorine atom or a monovalent organic group having 1 to 40 carbon atoms, or two or more of these groups are combined with each other. A part of a ring structure with 3 to 20 ring members formed together with these bonded carbon atoms. A ⁺ is a monovalent radioactive linium cation.

Examples of the monovalent organic group having 1 to 40 carbon atoms represented by R ⁷ , R ⁸ and R ⁹ include the same monovalent organic groups exemplified as R ¹² of the formula (3).

Examples of a ring structure with 3 to 20 ring members in which two or more of R ⁷ , R ⁸ and R ⁹ are bonded to each other and formed together with the bonded carbon atoms include: Alicyclic structure, aliphatic heterocyclic structure with 4 to 20 ring members, aromatic carbocyclic structure with 6 to 20 ring members, aromatic heterocyclic structure with 6 to 20 ring members, etc.

As an alicyclic structure with 3 to 20 ring members, an aliphatic heterocyclic structure with 4 to 20 ring members, an aromatic carbocyclic structure with 6 to 20 ring members, and an aromatic heterocyclic structure with 6 to 20 ring members. , for example, the same ring structures as the alicyclic structure, aliphatic heterocyclic structure, aromatic carbon ring structure and aromatic heterocyclic structure exemplified respectively as R ^p1 of the formula (5).

Examples of the monovalent radiation-sensitive onium cation represented by A ⁺ include the monovalent radiation-sensitive onium cation illustrated as T ⁺ in the formula (5).

As for R ⁷ , R ⁸ and R ⁹ , it is preferable that at least one of them is a fluorine atom, more preferably two of them are fluorine atoms, and it is still more preferable that R ⁷ and R ⁹ are fluorine atoms.

R ⁸ is preferably a monovalent organic group having 1 to 40 carbon atoms. Among them, a monovalent organic group having 1 to 40 carbon atoms containing a heteroatom other than a fluorine atom is more preferred. Examples of heteroatoms other than fluorine atoms include nitrogen atoms, oxygen atoms, and sulfur atoms, and an oxygen atom is preferred. R ⁸ is further preferably a monovalent organic group having 1 to 40 carbon atoms containing at least one selected from the group consisting of an ester structure, a ketone structure and a hydroxyl group. In addition, R ⁸ is also preferably a monovalent organic group having 1 to 40 carbon atoms having a ring structure. Examples of such a ring structure include an alicyclic structure, an aromatic carbocyclic structure, an aliphatic heterocyclic structure, and an aromatic heterocyclic structure. The specific ring structure is the same as described above. Among them, as the ring structure, an alicyclic structure is preferred, and a cycloalkyl ring and adamantane ring are more preferred. Alternatively, R ⁸ is preferably a monovalent organic group having 1 to 40 carbon atoms that does not contain a fluorine atom. Particularly preferably, R ⁷ and R ⁹ are fluorine atoms and R ⁸ is in this form.

A ⁺ is preferably the cation (ra), the cation (rb) or the cation (rc), more preferably the cation (ra) or the cation (rb), and further preferably the cation (rb). Cation (ra), particularly preferably triphenylsulfonium cation.

Examples of [C] compounds include compounds represented by the following formulas (2-1) to (2-15) (hereinafter also referred to as "compounds (2-1) to compounds (2-15)") wait.

In the formula (2-1) to formula (2-15), A ⁺ has the same meaning as the formula (2).

As the [C] compound, the compound (2-1)~ compound is preferred (2-7).

The lower limit of the content ratio of the [C] compound in the radiation-sensitive resin composition is preferably 1 mol%, more preferably 5 mol%, based on 100 mol% of the [B] acid generator. The best value is 10 mol%. The upper limit of the content ratio is preferably 200 mol%, more preferably 100 mol%, and still more preferably 50 mol%. By setting the content ratio of the [C] compound to the above range, the sensitivity and LWR performance of the resist pattern formed from the radiation-sensitive resin composition to exposure light can be further improved, and the process window can be further expanded. .

<[D]Organic solvent>

The radiation-sensitive resin composition usually contains [D] organic solvent. [D] The organic solvent is not particularly limited as long as it is a solvent that can dissolve or disperse at least the [A] polymer, [B] acid generator, [C] compound, and optionally contained optional components.

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

Examples of alcohol-based solvents include aliphatic monoalcohol solvents having 1 to 18 carbon atoms such as 4-methyl-2-pentanol and n-hexanol, and alicyclic monoalcohols having 3 to 18 carbon atoms such as cyclohexanol. It is a solvent, a polyol solvent with a carbon number of 2 to 18 such as 1,2-propanediol, a partial ether solvent of a polyol with a carbon number of 3 to 19 such as propylene glycol-1-monomethyl ether, etc.

Examples of the ether solvent include dialkyl ether solvents such as diethyl ether, dipropyl ether, dibutyl ether, dipyl ether, diisoamyl ether, dihexyl ether, and diheptyl ether, tetrahydrofuran, and tetrahydropyran. Such as cyclic ether solvents, diphenyl ether, anisole and other ether solvents containing aromatic rings, etc.

Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-isobutyl ketone, and 2-heptanone. , ethyl-n-butyl ketone, methyl-n-hexyl ketone, di-isobutyl ketone, trimethyl nonanone and other chain ketone solvents, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone , cyclic ketone solvents such as methylcyclohexanone, 2,4-pentanedione, acetonyl acetone, acetophenone, etc.

Examples of the amide-based solvent include cyclic amide-based solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone, N-methylformamide, N,N-dimethylformamide, and the like. Methylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpropionamide and other chain forms Amide solvents, etc.

Examples of the ester solvent include monocarboxylate solvents such as n-butyl acetate and ethyl lactate, lactone solvents such as γ-butyrolactone and valerolactone, and polyol carboxylic acid esters such as propylene glycol acetate. Solvents, polyol partial ether carboxylate solvents such as propylene glycol monomethyl ether acetate, polycarboxylic acid diester solvents such as diethyl oxalate, carbonate solvents such as dimethyl carbonate, diethyl carbonate, etc. wait.

Examples of the hydrocarbon solvent include aliphatic hydrocarbon solvents having 5 to 12 carbon atoms, such as n-pentane and n-hexane, and aromatic hydrocarbon solvents having 6 to 16 carbon atoms, such as toluene and xylene.

[D] The organic solvent is preferably an alcohol solvent or an ester solvent, more preferably a polyol partial ether solvent or a polyol partial ether carboxylate solvent having 3 to 19 carbon atoms, and even more preferably propylene glycol-1 -Monomethyl ether or propylene glycol monomethyl ether acetate. [D] The organic solvent may contain one type or two or more types.

When the radiation-sensitive resin composition contains [D] organic solvent Below, the lower limit of the content ratio of [D] organic solvent is preferably 50 mass %, more preferably 60 mass %, and still more preferably 70 mass % with respect to all components contained in the radiation-sensitive resin composition. , the best is 80 mass%. The upper limit of the content ratio is preferably 99.9 mass%, more preferably 99.5 mass%, and further preferably 99.0 mass%.

<Any other ingredients>

Examples of other optional components include acid diffusion control substances other than the [C] compound, surfactants, and the like. The radiation-sensitive resin composition may contain one or more other optional components.

[[C]Acid diffusion control substances other than compounds]

Examples of the content forms of other acid diffusion control agents other than the [C] compound in the radiation-sensitive resin composition include: forms of low molecular compounds (hereinafter also referred to as "other acid diffusion control agents"), as [ A] A form in which a part of a polymer such as a polymer is incorporated, or a form in which both of them are incorporated.

Examples of other acid diffusion control agents include compounds containing nitrogen atoms, photodegradable bases that are exposed to light and generate weak acids (excluding those equivalent to [C] compounds), and the like.

Examples of compounds containing nitrogen atoms include amine compounds such as tripentylamine and trioctylamine, amide group-containing compounds such as formamide and N,N-dimethylacetamide, urea, 1, Urea compounds such as 1-dimethylurea, pyridine, N-(undecylcarbonyloxyethyl)morpholine, N-tert-pentyloxycarbonyl-4-hydroxypiperidine and other nitrogen-containing heterocyclic compounds, etc.

Examples of the photodegradable base include onium which is decomposed by exposure to light. Compounds of cations and weakly acidic anions (excluding compounds equivalent to [C]), etc.

When the radiation-sensitive resin composition contains other acid diffusion control agents, the lower limit of the content ratio of the other acid diffusion control agents in the radiation-sensitive resin composition is 100 moles of [B] acid generator %, preferably 1 mol%, more preferably 5 mol%, even more preferably 10 mol%. The upper limit of the content ratio is preferably 200 mol%, more preferably 100 mol%, and still more preferably 50 mol%.

[Surfactant]

Surfactants have the effect of improving coating properties, streaks, developability, etc. Examples of surfactants include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, and polyoxyethylene n-nonylphenyl. Non-ionic surfactants such as ether, polyethylene glycol dilaurate, polyethylene glycol distearate, etc. Examples of commercially available products include: KP341 (Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, Polyflow No. 95 (the above, Kyoeisha Chemical Co., Ltd.) , Eftop EF301, Eftop EF303, Eftop EF352 (above, Tochem Products (shares)), Megafac F171, Megafac ( Megafac) F173 (above, DIC (shares)), Fluorad (Fluorad) FC430, Fluorad (Fluorad) FC431 (above, Sumitomo 3M (shares)), Asahi Guard AG710, Surflon S-382, Surflon SC-101, Surflon SC-102, Surflon SC-103, Surflon SC-104, Surflon SC-105, Surflon SC-106 (above, Asahi Glass Industry Co., Ltd.), etc.

When the radiation-sensitive resin composition contains a surfactant, the upper limit of the content of the surfactant in the radiation-sensitive resin composition is preferably 2 parts by mass relative to 100 parts by mass of the polymer [A] share. The lower limit of the content is, for example, 0.1 parts by mass.

<Preparation method of radiation-sensitive resin composition>

The radiation-sensitive resin composition can be obtained by mixing [A] polymer, [B] acid generator, [C] compound and optionally [D] organic solvent and other optional components in a predetermined ratio, for example. It is preferably prepared by filtering the obtained mixture through a membrane filter with a pore size of 0.2 μm or less.

The radiation-sensitive resin composition can be used for positive pattern formation using an alkaline developer, and can also be used for negative pattern formation using a developer containing an organic solvent.

This radiation-sensitive resin composition is used for exposure using radiation (exposure light) irradiated in the exposure step in the resist pattern forming method described below. Among the exposure lights, extreme ultraviolet (EUV) or electron beams have relatively high energy. However, according to the radiation-sensitive resin composition, even when extreme ultraviolet rays or electron beams are used as the exposure light, it is possible to form Resist pattern with good light sensitivity, excellent LWR performance, and wide process window. Therefore, the radiation-sensitive resin composition can be particularly preferably used for extreme ultraviolet exposure or electron beam exposure.

<Resist pattern formation method>

The resist pattern forming method includes: a step of directly or indirectly coating the radiation-sensitive resin composition on a substrate (hereinafter also referred to as a "coating step"); The step of exposing the resist film (hereinafter, also referred to as the "exposure step"); and the step of developing the exposed resist film (hereinafter, also referred to as the "development step").

According to this resist pattern forming method, by using the radiation-sensitive resin composition in the coating step, a resist pattern with good sensitivity to exposure light, excellent LWR performance, and a wide process window can be formed.

Each step included in this resist pattern forming method will be described below.

[Coating step]

In this step, the radiation-sensitive resin composition is directly or indirectly coated on the substrate. Thereby, a resist film is formed. Examples of the substrate include conventionally known ones such as silicon wafers, silicon dioxide, and aluminum-coated wafers. In addition, as the lower layer film, an organic or inorganic anti-reflection film disclosed in Japanese Patent Application Publication No. 6-12452, Japanese Patent Application Publication No. 59-93448, etc. may also be formed on the substrate. Examples of coating methods include spin coating (spin coating), cast coating, roll coating, and the like. After coating, in order to volatilize the solvent in the coating film, prebake (PB) may also be performed if necessary. The lower limit of the temperature of PB is preferably 60°C, more preferably 80°C. The upper limit of the temperature is preferably 150°C, more preferably 140°C. The lower limit of the PB time is preferably 5 seconds, more preferably 10 seconds. The upper limit of the time is preferably 600 seconds, more preferably 300 seconds. as a form The lower limit of the average thickness of the formed resist film is preferably 10 nm, more preferably 20 nm. The upper limit of the average thickness is preferably 1,000 nm, more preferably 500 nm.

[Exposure steps]

In this step, the resist film formed by the coating step is exposed. This exposure is performed by irradiating exposure light through a light mask (or through a liquid immersion medium such as water, as appropriate). Examples of the exposure light include, depending on the line width of the target pattern, electromagnetic waves such as visible rays, ultraviolet rays, far ultraviolet rays, extreme ultraviolet rays (EUV), X-rays, and gamma rays; and charged particle beams such as electron beams and alpha rays. Among these, far ultraviolet light, EUV or electron beam is preferred, ArF excimer laser light (wavelength 193nm), KrF excimer laser light (wavelength 248nm), EUV or electron beam is more preferred, and ArF excimer laser light is even more preferred. Radiation light, EUV or electron beam, particularly preferably EUV or electron beam. In addition, exposure conditions such as exposure amount can be appropriately selected based on the compounding composition of the radiation-sensitive resin composition, the type of additives, the type of exposure light, and the like.

Preferably, post exposure bake (PEB) is performed after the exposure, and the acid generated from the [B] acid generator or the like by exposure is used to promote the exposed portion of the resist film. [A] Dissociation of the acid-dissociable group contained in the polymer. This PEB can increase the difference in solubility to the developer between the exposed portion and the unexposed portion. The lower limit of the temperature of PEB is preferably 50°C, more preferably 80°C, and even more preferably 90°C. The upper limit of the temperature is preferably 180°C, more preferably 130°C. The lower limit of the PEB time is preferably 5 seconds, more preferably 10 seconds, and still more preferably 30 seconds. The upper limit of the time is preferably 600 seconds, more preferably 300 seconds, and still more preferably 100 seconds.

[Development step]

In this step, the exposed resist film is developed. Thereby, a predetermined resist pattern can be formed. Generally speaking, after development, the eluent such as water or alcohol is used for cleaning and drying. The development method in the development step may be alkali development or organic solvent development.

In the case of alkali development, examples of the developer used for development include dissolved sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, Diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethyl ammonium hydroxide (TMAH), pyrrole, piperazine alkaloids, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, 1,5-diazabicyclo-[4.3.0]-5-nonene and other basic compounds At least one alkaline aqueous solution, etc. Among these, a TMAH aqueous solution is preferred, and a 2.38 mass% TMAH aqueous solution is more preferred.

In the case of organic solvent development, examples of the developer include organic solvents such as hydrocarbon-based solvents, ether-based solvents, ester-based solvents, ketone-based solvents, and alcohol-based solvents, and solvents containing these organic solvents. Examples of the organic solvent include one, two or more solvents exemplified as the organic solvent [D] of the radiation-sensitive resin composition. Among these, an ester solvent or a ketone solvent is preferred. As the ester solvent, an acetate solvent is preferred, and n-butyl acetate is more preferred. As the ketone solvent, chain ketones are preferred, and 2-heptanone is more preferred. The lower limit of the organic solvent content in the developer is preferably 80 mass%, more preferably 90 mass%, further preferably 95 mass%, and particularly preferably 99 mass%. As components other than organic solvents in the developer, Examples include water, silicone oil, and the like.

Examples of the development method include: a method in which the substrate is immersed in a tank filled with a developer for a fixed period of time (immersion method); a method in which the developer is deposited on the surface of the substrate using surface tension and left to stand for a fixed period of time (coating method). puddle method); a method of spraying a developer solution on the surface of a substrate (spray method); a method of continuously spraying a developer solution toward a substrate rotating at a fixed speed while scanning the developer ejection nozzle at a fixed speed (dynamic distribution method) )wait.

Examples of patterns formed by this resist pattern forming method include line and space patterns, hole patterns, and the like.

[Example]

Hereinafter, the present invention will be described in detail based on Examples, but the present invention is not limited to these Examples. Methods for measuring various physical property values are shown below.

[Weight average molecular weight (Mw), number average molecular weight (Mn) and dispersion (Mw/Mn)]

The Mw and Mn of the polymer were measured by gel permeation chromatography (GPC) using Tosoh Co., Ltd.'s GPC columns (two "G2000HXL", one "G3000HXL", and one "G4000HXL" roots), measured according to the following conditions. In addition, the degree of dispersion (Mw/Mn) is calculated based on the measurement results of Mw and Mn.

Dissolution solvent: tetrahydrofuran

Flow: 1.0mL/min

Sample concentration: 1.0 mass%

Sample injection volume: 100μL

Tube string temperature: 40℃

Detector: Differential Refractometer

Standard material: monodisperse polystyrene

[Content ratio of each structural unit in the polymer]

The content ratio of each structural unit in the polymer was determined by ¹³ C-NMR analysis using a nuclear magnetic resonance apparatus ("JNM-Delta 400" of JEOL Ltd.).

<Synthesis of [A]Polymer>

The monomers used for the synthesis of each polymer in each Example and Comparative Example are shown below. In addition, in the following synthesis examples, unless otherwise specified, the mass part refers to the value when the total mass of the monomers used is 100 mass parts, and the mole % refers to the value when the monoliths used are used. The value when the total mole number of the body is set to 100 mol%.

[Synthesis Example 1] Synthesis of polymer (A-1)

Dissolve monomer (M-1), monomer (M-3) and monomer (M-10) in propylene glycol-1- so that the molar ratio becomes 40/40/20 (mol%). AIBN (6 mol%) as a starting agent was added to monomethyl ether (200 parts by mass) to prepare a monomer solution. Propylene glycol-1-monomethyl ether (100 parts by mass) was placed in an empty reaction vessel, and the mixture was heated to 85°C while stirring. Next, the monomer solution was dropped into the reaction vessel over 3 hours, and further heated at 85° C. for 3 hours. The start of the dropwise addition of the monomer solution was set as the start time of the polymerization reaction, and a total of 6 hours of polymerization. After the polymerization reaction is completed, the polymerization solution is cooled to room temperature. The cooled polymerization solution was put into hexane (500 parts by mass relative to 100 parts by mass of the polymerization solution), and the precipitated white powder was separated by filtration. The white powder separated by filtration was washed twice with hexane (100 parts by mass relative to 100 parts by mass of the polymerization solution), and then separated by filtration and dissolved in propylene glycol-1-monomethyl ether (300 parts by mass). Next, methanol (500 parts by mass), triethylamine (50 parts by mass) and ultrapure water (10 parts by mass) were added, and a hydrolysis reaction was performed at 70° C. for 6 hours while stirring. After the hydrolysis reaction was completed, the residual solvent was distilled off, and the obtained solid was dissolved in acetone (100 parts by mass). This solution was added dropwise to 500 parts by mass of water to solidify the resin, and the obtained solid was separated by filtration and dried at 50° C. for 12 hours to obtain a white powdery polymer (A-1). The Mw of polymer (A-1) is 5600, and Mw/Mn is 1.62. In addition, the results of ¹³ C-NMR analysis showed that the content ratios of each structural unit derived from (M-1), (M-3) and (M-10) were 42.3 mol%, 39.8 mol% and 17.9 respectively. Mol%.

[Synthesis Example 2 to Synthesis Example 8] Polymer (A-2) to Polymer (A-8) synthesis

Polymers (A-2) to (A-8) were synthesized in the same manner as in Synthesis Example 1, except that monomers of the types and blending ratios shown in Table 1 below were used. Table 1 below shows the content ratio of each structural unit and the physical property values (Mw and Mw/Mn) of the obtained polymer. In addition, "-" in Table 1 below indicates that the corresponding monomer is not used.

[Synthesis Example 9] Synthesis of polymer (A-9)

The monomers of the types and blending ratios shown in Table 1 below were synthesized by the same method as the synthesis method of "polymer (B-3-1)" described in Japanese Patent Application Laid-Open No. 2009-244805. Aggregate (A-9). Table 1 below shows the content ratio of each structural unit and the physical property values (Mw and Mw/Mn) of the obtained polymer.

[Table 1]

<Preparation of radiation-sensitive resin composition>

Components other than the polymer [A] used in the preparation of the radiation-sensitive resin composition are shown below. In addition, in the following Examples and Comparative Examples, unless otherwise specified, the mass part refers to the value when the mass of the polymer used is 100 mass parts, and the molar % refers to the [B ] The value when the molar number of the acid generator is set to 100 mol%.

[[B]Acid generator]

B-1 to B-4: Compounds represented by the following formulas (B-1) to formula (B-4)

[[C]Acid diffusion control agent]

C-1 to C-9: Compounds represented by the following formulas (C-1) to formula (C-9)

[Chemistry 22]

[[D]Organic solvent]

D-1: Propylene glycol monomethyl ether acetate

D-2: Propylene glycol-1-monomethyl ether

[Example 1]

100 parts by mass of (A-1) as [A] polymer, 20 parts by mass of (B-1) as [B] acid generator, and 20 mol% of (C) as [C] acid diffusion control agent -1) Prepare a radiation-sensitive resin composition by mixing 4800 parts by mass of (D-1) and 2000 parts by mass of (D-2) as [D] organic solvent, and filtering with a membrane filter with a pore size of 0.2 μm. Object (R-1).

[Example 2 to Example 14 and Comparative Example 1 to Comparative Example 3]

The radiation-sensitive resin composition (R-2) to the radiation-sensitive resin composition (R-14) and the radiation-sensitive resin composition (R-14) were prepared in the same manner as in Example 1 except that the types and contents of each component shown in Table 2 below were used. Radioactive resin composition (CR-1)~radiation-sensitive resin composition (CR-3).

<Formation of resist pattern (EUV exposure, alkali development)>

The radiation-sensitive resin composition prepared as described above was coated on an underlayer film having an average thickness of 20 nm ( Soft bake (SB) was performed at 130°C for 60 seconds on the lower film of a 12-inch silicon wafer (Brewer Science's "AL412"). Thereafter, a resist film having an average thickness of 50 nm was formed by cooling at 23° C. for 30 seconds. Next, the resist film was exposed using an EUV exposure device (ASML's "NEX3300") under NA=0.33, lighting conditions: Conventional s=0.89, and mask: imecDEFECT32FFR02. After exposure, use 2.38% by mass TMAH solution was used as an alkaline developer and developed at 23°C for 30 seconds to form a positive resist pattern (32nm line and space pattern).

<evaluation>

For the formed resist pattern, the sensitivity, LWR performance and process window were evaluated according to the following methods. For the length measurement of the resist pattern, a scanning electron microscope ("CG-4100" manufactured by Hitachi High-Technologies Co., Ltd.) was used. The evaluation results are shown in Table 3 below. In addition, "-" in the following Table 3 indicates that in Comparative Example 2, since the unexposed portion was also dissolved in the alkaline developer and a resist pattern was not formed, various evaluations could not be performed.

[Sensitivity]

In the formation of the resist pattern, the exposure amount to form a 32 nm line and space pattern was regarded as the optimal exposure amount, and the optimal exposure amount was regarded as the sensitivity (mJ/cm ² ). Regarding the sensitivity, a sensitivity of 30 mJ/cm ² or less can be evaluated as "good", and a sensitivity exceeding 30 mJ/cm ² can be evaluated as "poor".

[LWR performance]

Using the scanning electron microscope, the formed resist pattern was observed from the upper portion of the resist pattern. A total of 50 line widths were measured at any location, and a 3 sigma value was calculated based on the distribution of the measured values. This 3 sigma value was set to LWR (nm). The smaller the value of LWR, the smaller the jitter of the line and the better it is. As for the LWR performance, the case where the thickness is 4.0nm or less can be evaluated as "good", and the case where it exceeds 4.0nm can be evaluated as "poor".

[Process window]

The so-called "process window" refers to the range of resist dimensions that can form patterns without bridging defects or collapse. Use a mask that forms a 32nm line and space pattern (1L/1S) to form patterns from low exposure to high exposure. Generally speaking, under low exposure conditions, defects such as the formation of bridges between patterns are seen, and under high exposure conditions, defects such as pattern collapse are seen. The difference between the maximum value and the minimum value of the resist size where these defects cannot be seen is set as the "Critical Dimension (CD) margin". The larger the value of CD margin, the wider and better the process window is. A CD margin of 30 nm or more can be evaluated as "good", and a CD margin of less than 30 nm can be evaluated as "poor".

From the results in Table 3, it is clear that the radiation-sensitive resin composition of the Example has better sensitivity, LWR performance, and CD margin than the radiation-sensitive resin composition of the Comparative Example.

[Industrial availability]

According to the radiation-sensitive resin composition and resist pattern forming method of the present invention, a resist pattern with good sensitivity to exposure light, excellent LWR performance, and a wide process window can be formed. Therefore, these can be suitably used in processing processes of semiconductor devices that are expected to be further miniaturized in the future.

Claims (6)

A radiation-sensitive resin composition containing a polymer having a first structural unit including a phenolic hydroxyl group, a second structural unit including a group represented by the following formula (1), and a third structure including an acid-dissociable group A unit; a radiosensitive acid generator; and a compound represented by the following formula (2),

(In formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are each independently a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom or a carbon number of 1 to 10. fluorinated hydrocarbon group; wherein, at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ is a fluorine atom or a fluorinated hydrocarbon group; R ^A is a hydrogen atom or a monovalent fluorinated hydrocarbon group with 1 to 20 carbon atoms. Organic group; * represents a bonding site with a part other than the group represented by the formula (1) in the second structural unit)

(In formula (2), R ⁷ and R ⁹ are fluorine atoms, R ⁸ is a monovalent organic group with 1 to 40 carbon atoms containing at least one selected from the group consisting of an ester structure and a ketone structure; A ⁺ is a monovalent hydroxyl group. radioactive onium cations). The radiation-sensitive resin composition according to claim 1, wherein the phase The content ratio of the third structural unit in the polymer is 30 mol% or more and 80 mol% or less with respect to all the structural units constituting the polymer. The radiation-sensitive resin composition according to claim 1, wherein the first structural unit is represented by the following formula (3),

(In formula (3), R ¹⁰ is a hydrogen atom, fluorine atom, methyl or trifluoromethyl; R ¹¹ is a single bond, -O-, -COO- or -CONH-; Ar is a self-ring member number 6~ 20 aromatic hydrocarbons are groups formed by removing (p+q+1) hydrogen atoms from the aromatic ring; p is an integer from 0 to 10; when p is 1, R ¹² is a carbon number from 1 to 20 A valent organic group or a halogen atom; when p is 2 or more, multiple R ^12s are the same as or different from each other, and are monovalent organic groups or halogen atoms with a carbon number of 1 to 20, or two of multiple R ^12s The above combined with each other and the bonded carbon chains form part of a ring structure with 4 to 20 ring members; q is an integer from 1 to 11; where p+q is 11 or less). The radiation-sensitive resin composition according to claim 1, wherein the third structural unit is composed of the following formula (4-1A), formula (4-1B), formula (4-1C), formula (4- 2A) or represented by formula (4-2B),

(In formula (4-1A), formula (4-1B), formula (4-1C), formula (4-2A) and formula (4-2B), R ^T is independently a hydrogen atom, a fluorine atom, a methyl group or trifluoromethyl; in formula (4-1A ⁾ and formula (4-1B ⁾ , ^R A monovalent hydrocarbon group with 1 to 20 carbon atoms, or part of an alicyclic structure with 3 to 20 ring members formed by R ^Y and R ^Z combined with each other and the bonded carbon atoms; formula (4-1C ), ^RC is a hydrogen atom; ^RD and ^RE are independently hydrogen atoms or monovalent hydrocarbon groups with 1 to 20 carbon atoms; ^RF is the carbon atom bonded to ^RC , ^RD and ^RE respectively. A divalent hydrocarbon group with 1 to 20 carbon atoms that together constitute an unsaturated alicyclic structure with 4 to 20 ring members; in formula (4-2A) and formula (4-2B), R ^U and R ^V are each independently hydrogen Atoms or monovalent hydrocarbon groups with 1 to 20 carbon atoms. R ^{and W} are independently monovalent hydrocarbon groups with 1 to 20 carbon atoms, or R ^U and R ^V are combined with each other and are composed of these bonded carbon atoms. Part of an alicyclic structure with ring members of 3 to 20, or a ring member of 5 to 20 composed of R ^U and R ^W bonded to each other and together with the carbon atom to which R ^U is bonded and the oxygen atom to which R ^W is bonded. part of the aliphatic heterocyclic structure). The radiation-sensitive resin composition according to claim 1 is used for extreme ultraviolet exposure or electron beam exposure. A resist pattern forming method, including: a step of directly or indirectly coating a radiation-sensitive resin composition on a substrate; a step of exposing the resist film formed by the coating step; and In the step of developing the resist film after the exposure step, the radiation-sensitive resin composition contains: a polymer having a first structural unit including a phenolic hydroxyl group, and a group represented by the following formula (1) The second structural unit and the third structural unit including an acid-dissociating group; a radiation-sensitive acid generator; and a compound represented by the following formula (2),

(In formula (1), R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are each independently a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom or a carbon number of 1 to 10. fluorinated hydrocarbon group; wherein, at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ is a fluorine atom or a fluorinated hydrocarbon group; R ^A is a hydrogen atom or a monovalent fluorinated hydrocarbon group with 1 to 20 carbon atoms. Organic group; * represents a bonding site with a part other than the group represented by the formula (1) in the second structural unit)

(In formula (2), R ⁷ and R ⁹ are fluorine atoms, R ⁸ is a monovalent organic group with 1 to 40 carbon atoms containing at least one selected from the group consisting of ester structure and ketone structure; A ⁺ is a monovalent hydroxyl group. radioactive onium cations).