JP7459636B2 - Radiation-sensitive resin composition and method for forming resist pattern - Google Patents

Description

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

The radiation-sensitive resin composition used for microfabrication by lithography is capable of radiating far ultraviolet rays such as ArF excimer laser light (wavelength 193 nm) and KrF excimer laser light (wavelength 248 nm), extreme ultraviolet rays (EUV) (wavelength 13.5 nm), etc. Acid is generated in the exposed area by irradiation with radiation such as electromagnetic waves or charged particle beams such as electron beams, and a chemical reaction using this acid as a catalyst causes a difference in the rate of dissolution in the developer between the exposed area and the unexposed area. , forming a resist pattern on the substrate.

Such radiation-sensitive compositions have good sensitivity to exposure light such as extreme ultraviolet rays and electron beams, as well as excellent LWR (Line Width Roughness) performance, which indicates uniformity of line width. required.

To meet these demands, the types and molecular structures of polymers and other components used in radiation-sensitive resin compositions have been studied, and their combinations have also been studied in detail (Japanese Patent Laid-Open No. 2009-244805). (see Japanese Patent Application Publication No. 2004-012510 and Japanese Patent Application Publication No. 2017-141373).

Japanese Patent Application Publication No. 2009-244805 Japanese Patent Application Publication No. 2004-012510 JP 2017-141373 A

As resist patterns become further finer, the influence of slight fluctuations in exposure and development conditions on the resist pattern shape and the occurrence of defects is becoming more and more significant. There is also a need for a radiation-sensitive resin composition with a wide process window (process latitude) that can absorb such slight fluctuations in process conditions. However, the above-mentioned conventional radiation-sensitive resin compositions have not been able to meet these requirements.

The present invention was made based on the above-mentioned circumstances, and its object is to provide a radiation-sensitive resin composition and a method for forming a resist pattern that have good sensitivity to exposure light, excellent LWR performance, and can form a resist pattern with a wide process window.

（式（１）中、Ｒ^１、Ｒ^２、Ｒ^３、Ｒ^４、Ｒ^５及びＲ^６は、それぞれ独立して、水素原子、フッ素原子、塩素原子、臭素原子、ヨウ素原子又は炭素数１～１０の１価のフッ素化炭化水素基である。但し、Ｒ^１、Ｒ^２、Ｒ^３、Ｒ^４、Ｒ^５及びＲ^６のうちの少なくとも１つはフッ素原子又はフッ素化炭化水素基である。Ｒ^Ａは、水素原子又は炭素数１～２０の１価の有機基である。＊は、上記第２構造単位における上記式（１）で表される基以外の部分との結合部位を示す。）

（式（２）中、Ｒ^７、Ｒ^８及びＲ^９は、それぞれ独立して、水素原子、フッ素原子若しくは炭素数１～４０の１価の有機基であるか、又はこれらの基のうちの２つ以上が互いに合わせられこれらが結合する炭素原子と共に構成される環員数３～２０の環構造の一部である。Ａ^＋は、１価の感放射線性オニウムカチオンである。） The invention made to solve the above-mentioned problems is a radiation-sensitive resin composition containing a polymer (hereinafter also referred to as "polymer [A]") having a first structural unit containing a phenolic hydroxyl group, a second structural unit containing a group represented by the following formula (1), and a third structural unit containing an acid-dissociable group, a radiation-sensitive acid generator (hereinafter also referred to as "acid generator [B]"), and a compound represented by the following formula (2) (hereinafter also referred to as "compound [C]"):

(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 monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms, provided that 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. * indicates a bonding site to a portion other than the group represented by 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 combined with the carbon atoms to which they are bonded form a ring structure having 3 to 20 ring members. A ⁺ is a monovalent radiation-sensitive onium cation.)

Another invention made to solve the above problems includes a step of directly or indirectly coating the radiation-sensitive resin composition on a substrate, a step of exposing a resist film formed by the above coating step, This is a resist pattern forming method comprising a step of developing the resist film after the exposure step.

The radiation-sensitive resin composition and resist pattern forming method of the present invention can form a resist pattern that has good sensitivity to exposure light, excellent LWR performance, and a wide process window. Therefore, they can be suitably used in the processing of semiconductor devices, which are expected to become even more miniaturized in the future.

<Radiation-sensitive resin composition>
The radiation-sensitive resin composition contains a polymer [A], an acid generator [B], and a compound [C]. The radiation-sensitive resin composition may contain a solvent (hereinafter, also referred to as "organic solvent [D]") as a suitable component, and may contain other optional components within the scope not impairing the effects of the present invention.

The radiation-sensitive resin composition contains the polymer [A], the acid generator [B], and the compound [C], and thus has good sensitivity to exposure light, excellent LWR performance, and can form a resist pattern with a wide process window. The reason why the radiation-sensitive resin composition has the above-mentioned configuration is not necessarily clear, but it can be inferred, for example, as follows. That is, the polymer [A] contained in the radiation-sensitive resin composition has a first structural unit containing a phenolic hydroxyl group and a second structural unit containing a group represented by the above formula (1), and thus the solubility in the developer is improved. Furthermore, the radiation-sensitive resin composition contains the compound [C], and thus the solubility in the developer is further improved. As a result, it is believed that the radiation-sensitive resin composition can form a resist pattern that has good sensitivity to exposure light, excellent LWR performance, and a wide process window.

The components contained in the radiation-sensitive resin composition are described below.

<Polymer (A)>
The polymer [A] has a first structural unit (hereinafter also simply referred to as "first structural unit") containing a phenolic hydroxyl group, a second structural unit (hereinafter also simply referred to as "second structural unit") containing a group represented by the above formula (1), and a third structural unit (hereinafter also simply referred to as "third structural unit") containing an acid-dissociable group. The polymer [A] may have structural units other than the first structural unit, the second structural unit, and the third structural unit. The polymer [A] may have one or more types of each structural unit.

The structural units contained in polymer [A] are explained below.

[First structural unit]
The first structural unit is a structural unit containing a phenolic hydroxyl group. The term "phenolic hydroxyl group" refers not only to a hydroxyl group directly bonded to a benzene ring, but also to any hydroxyl group directly bonded to an aromatic ring. The polymer [A] having the first structural unit can increase the hydrophilicity of the resist film, can appropriately adjust the solubility in a developer, and can improve the adhesion of the resist pattern to a substrate. In addition, when extreme ultraviolet rays or electron beams are used as the radiation to be irradiated in the exposure step in the resist pattern forming method described later, 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).

In the above 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 hydrogen atoms on (p+q+1) aromatic rings from an arene having 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 multiple R ¹² are the same or different from each other and are a monovalent organic group having 1 to 20 carbon atoms or a halogen atom, or two or more of the multiple R ¹² are combined with each other to form a part of a ring structure having 4 to 20 ring members together with the carbon chain to which they are bonded. q is an integer from 1 to 11. However, p+q is 11 or less.

From the viewpoint of copolymerizability of the monomer that provides the first structural unit, R ¹⁰ is preferably a hydrogen atom or a methyl group.

When R ¹¹ is -COO-, it is preferable that an oxyoxygen atom is bonded to Ar, and when R ¹¹ is -CONH-, it is preferable that a nitrogen atom is bonded to Ar. That is, if ** indicates the bonding site with Ar, -COO- is preferably -COO-**, and -CONH- is preferably -CONH-**. R ¹¹ is preferably a single bond or -COO-, and more preferably a single bond.

"Number of ring members" refers to the number of atoms constituting the rings of alicyclic structures, aromatic carbocyclic structures, aliphatic heterocyclic structures, and aromatic heterocyclic structures; Refers to the number of atoms.

Examples of arenes having 6 to 20 ring members that give Ar include benzene, naphthalene, anthracene, phenanthrene, tetracene, pyrene, etc. Ar is preferably benzene or naphthalene, and more preferably benzene.

"Organic group" refers to a group containing at least one carbon atom. "Number of carbon atoms" refers to the number of carbon atoms constituting a 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 divalent hetero atom-containing between carbon atoms of this hydrocarbon group. a group containing a group (α), a group (β) in which some or all of the hydrogen atoms of the above hydrocarbon group and the above divalent heteroatom-containing group are substituted with a monovalent heteroatom-containing group; Examples include a hydrocarbon group, a group (α), or a group (γ) that is a combination of a group (β) and a divalent heteroatom-containing group.

"Hydrocarbon group" includes linear hydrocarbon group, alicyclic hydrocarbon group, and aromatic hydrocarbon group. This "hydrocarbon group" may be a saturated or unsaturated hydrocarbon group. "Linear hydrocarbon group" refers to a hydrocarbon group that does not include a cyclic structure and is composed only of a linear structure, and includes both linear hydrocarbon group and branched hydrocarbon group. "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 both monocyclic alicyclic hydrocarbon group and polycyclic alicyclic hydrocarbon group. However, it does not have to be composed only of an alicyclic structure, and it may include a linear structure as part of it. "Aromatic hydrocarbon group" refers to a hydrocarbon group that includes an aromatic ring structure as a ring structure. However, it does not have to be composed only of an aromatic ring structure, and it may include a linear structure or an alicyclic structure as part of it.

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

Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include alkyl groups such as methyl group, ethyl group, n-propyl group, and i-propyl group, and alkenyl groups such as ethenyl group, propenyl group, and butenyl group. , alkynyl groups such as ethynyl group, propynyl group, butynyl group, and the like.

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

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

Examples of the heteroatoms constituting the monovalent and divalent heteroatom-containing groups 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 divalent heteroatom-containing groups include -O-, -CO-, -S-, -CS-, -NR'-, and groups that combine 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 ring structures having 4 to 20 ring members in which two or more of a plurality of R ¹² are combined together with carbon chains to which they are bonded include cyclopentane structure, cyclohexane structure, cyclopentene structure, cyclohexene structure, etc. Examples include alicyclic structures.

p is preferably 0 to 2, more preferably 0 or 1, and even more preferably 0.

q is preferably 1 to 3, more preferably 1 or 2.

Examples of the first structural unit include structural units represented by the following formulas (3-1) to (3-12).

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

As the first structural unit, a structural unit represented by the above formula (3-1) or (3-2) is preferable.

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

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

In the above 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 monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms, provided that 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. * indicates a bonding site in the above second structural unit to a portion other than the group represented by the above formula (1).

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

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R 1 ^A include the same monovalent organic groups as exemplified as R ¹² in the above 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; A valent fluorinated alkyl group is more preferred, and a fluorine atom is even more preferred.

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 at least two of R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ 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, further preferably R ¹ , R ² , R ³ , R 4 , ^{R 5} and R ⁶ are fluorine atoms or fluorinated hydrocarbon groups, and particularly preferably R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are fluorine atoms.

R ^A is preferably a hydrogen atom.

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

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

In the above formula (1-1), L is a single bond or -COO-. R ^a2 is a (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, multiple Xs are the same or different.

In the above 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 having 1 to 10 carbon atoms, or R ^a5 and R ^a6 are bonded to each other to form a part of a ring structure having 3 to 20 ring members together with the carbon atom to which they are bonded.

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

L is preferably -COO-. When L is -COO-, it is preferable that the oxyoxygen atom is bonded to R ^a2 . That is, when *** represents the bonding site with R ^a2 , -COO- is preferably -COO-***.

Examples of R ^a2 include groups in which n hydrogen atoms have been removed from the monovalent organic groups exemplified as R ¹² in the above 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.

n is preferably 1 or 2, and more preferably 1.

Examples of R ^a3 include groups in which one hydrogen atom has been removed from the monovalent hydrocarbon groups exemplified as R ¹² in the above formula (3). R ^a3 is preferably a chain hydrocarbon group, and more preferably a saturated chain hydrocarbon group.

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

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

Examples of the ring structure having 3 to 20 ring members formed by R ^a5 and R ^a6 bonding to each other together with the carbon atom to which they are bonded include alicyclic structures having 3 to 20 ring members.

Among the second structural units, examples of the structural unit represented by the above formula (1-1) include structural units represented by the following formulas (1-1-1) to (1-1-3). It will be done.

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

Among the second structural units, the structural unit represented by the above formula (1-2) includes, for example, the structural unit represented by the following formula (1-2-1).

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

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

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

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

Examples of the third structural unit include structural units represented by the following formulas (4-1A), (4-1B), (4-2A), or (4-2B). ^{In addition} , ⁱⁿ the following formulas (4-1A) to ( ^4-2B ) ^{, -CR} It is an acid dissociable group.

In the above formulas (4-1A), (4-1B), (4-1C), (4-2A) and (4-2B), R 1 ^T each independently represents a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

In the above formulas (4-1A) and (4-1B), R ^{1 X} is each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^{1 Y} and R 1 ^Z are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or R 1 ^Y and R 1 ^Z taken together with the carbon atom to which they are bonded are part of an alicyclic structure having 3 to 20 ring members.

In the above 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. R ^F is a divalent hydrocarbon group having 1 to 20 carbon atoms which, together with the carbon atoms to which R ^C , R ^D , and R ^E are each bonded, constitutes an unsaturated alicyclic structure having 4 to 20 ring members.

In the above formulas (4-2A) and (4-2B), R ^U and R ^V are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ^W is each Independently, it is a monovalent hydrocarbon group having 1 to 20 carbon atoms, or an alicyclic structure having 3 to 20 ring members formed by combining R ^U and R ^V together with the carbon atoms to which they are bonded. or is part of an aliphatic heterocyclic structure having 5 to 20 ring members, in which R ^U and R ^W are combined together with the carbon atom to which R ^U is bonded and the oxygen atom to which R ^W is bonded. .

R 1 ^T is preferably a hydrogen atom or a methyl group from the viewpoint of copolymerizability of the monomer that provides the third structural unit.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^X , R ^Y , R ^Z , R ^D , R ^E , R ^U , R ^V , and R ^W include the same groups as the hydrocarbon groups exemplified as R ¹² in the above formula (3).

Examples of the divalent hydrocarbon group having 1 to 20 carbon atoms represented by R 2 ^F include groups in which one hydrogen atom has been removed from the monovalent hydrocarbon groups exemplified as R ¹² in the above formula (3).

Examples of the alicyclic structure having 3 to 20 ring members constituted by combining R ^Y and R ^Z or R ^U and R ^V with each other and the carbon atoms to which they are bonded include monocyclic saturated alicyclic structures such as a cyclopropane structure, a cyclobutane structure, a cyclopentane structure, and a cyclohexane structure; polycyclic saturated alicyclic structures such as a norbornane structure, an adamantane structure, a tricyclodecane structure, and a tetracyclododecane structure; monocyclic unsaturated alicyclic structures such as a cyclopropene structure, a cyclobutene structure, a cyclopentene structure, and a cyclohexene structure; and polycyclic unsaturated alicyclic structures such as a norbornene structure, a tricyclodecene structure, and a tetracyclododecene structure.

Examples of aliphatic heterocyclic structures having 5 to 20 ring members, which are formed by combining R ^U and R ^W together with the carbon atom to which R ^U is bonded and the oxygen atom to which R ^W is bonded, include oxacyclobutane structure, oxacyclopentane structure, etc. structure, a saturated oxygen-containing heterocyclic structure such as an oxacyclohexane structure, an unsaturated oxygen-containing heterocyclic structure such as an oxacyclobutene structure, an oxacyclopentene structure, an oxacyclohexene structure, and the like.

Examples of the unsaturated alicyclic structure having 4 to 20 ring members constituted by R ^F together with the carbon atoms to which R ^C , R ^D and R ^E are bonded include unsaturated alicyclic structures such as a cyclobutene structure, a cyclopentene structure, a cyclohexene structure and a norbornene structure.

R ^{1 X} is preferably a hydrocarbon group, more preferably a chain hydrocarbon group or an aromatic hydrocarbon group, and further preferably an alkyl group or an aryl group.

R ^{1 Y} and R 1 ^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, and more preferably a hydrogen atom.

R ^V and R ^W are preferably hydrocarbon groups, and more preferably chain hydrocarbon groups.

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

[A] The lower limit of the content of the third structural unit in the polymer is preferably 5 mol%, more preferably 10 mol%, and 15 mol% based on the total structural units constituting the polymer [A]. More preferred. The upper limit of the content ratio is preferably 80 mol%, more preferably 70 mol%, and even more preferably 60 mol%. By setting the content ratio of the third structural unit within the above range, the sensitivity to exposure light and LWR performance of the resist pattern formed by the radiation-sensitive resin composition can be further improved, and the process window can be further expanded. be able to.

[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, a structural unit containing an alcoholic hydroxyl group other than the second structural unit, and a structural unit derived from benzyl (meth)acrylate. Examples include. [A] By further having these other structural units, the polymer can further adjust its solubility in the developer, and as a result, the resist formed from the radiation-sensitive resin composition The sensitivity of the pattern to exposure light and the LWR performance can be further improved, and the process window can be further expanded. Furthermore, the adhesion between the resist pattern and the substrate can be further improved.

Examples of the structural unit containing a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination thereof include a structural unit represented by the following formula.

In the above 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 thereof, a structural unit containing a lactone structure is preferred, a structural unit containing a norbornane lactone structure is more preferred, and a structural unit derived from norbornane lactone-yl (meth)acrylate is even more preferred.

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

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

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

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

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

In this specification, the Mw and Mn of the polymer are values measured by gel permeation chromatography (GPC) under the following conditions.
GPC columns: two "G2000HXL", one "G3000HXL" and one "G4000HXL" from Tosoh Corporation. Elution solvent: tetrahydrofuran. Flow rate: 1.0 mL/min. Sample concentration: 1.0% by mass.
Sample injection volume: 100 μL
Column temperature: 40°C
Detector: Differential refractometer Standard material: Monodisperse polystyrene

The lower limit of the content of the [A] polymer in the radiation-sensitive resin composition is preferably 50% by mass, more preferably 60% by mass, and 70% by mass based on all components other than the organic solvent [D]. is more preferable, and 80% by mass is particularly preferable.

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

<[B] Acid generator>
[B] Acid generator is a substance that generates acid upon irradiation with radiation. Examples of the radiation include electromagnetic waves such as visible light, 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. Upon irradiation with radiation (exposure), the acid generated from the acid generator [B] dissociates the acid-dissociable group contained in the third structural unit of the polymer [A] to form a carboxyl group, which separates the exposed and unexposed areas. A resist pattern can be formed by the difference in the solubility of the [A] polymer in a developer between the two parts. The [B] acid generator contained in the radiation-sensitive resin composition may be in the form of a low molecular compound (hereinafter also referred to as "[B] acid generator"), or incorporated as part of the [A] polymer. or both of these forms.

The lower limit of the temperature at which the acid dissociates the acid-dissociable group is preferably 80°C, more preferably 90°C, and even more preferably 100°C. The upper limit of the above 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-dissociable group is preferably 10 seconds, more preferably 1 minute. The upper limit of the above time is preferably 10 minutes, more preferably 2 minutes.

[B] Examples of acids generated from the acid generator include sulfonic acids and imide acids.

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

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

Examples of the acid generator [B] that generates sulfonic acid upon irradiation with radiation include a compound represented by the following formula (5) (hereinafter also referred to as "compound (5)"). [B] When the acid generator has the following structure, it is thought that the diffusion length of the generated acid in the resist film becomes more appropriately shortened due to interaction with the [A] polymer, and as a result, the said sensitivity The sensitivity to exposure light and the LWR performance of the resist pattern formed by the radiation-active resin composition can be further improved, and the process window can be further expanded.

In the above formula (5), R ^p1 is a monovalent group containing a ring structure having 5 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 from 0 to 10. n ^p2 is an integer from 0 to 10. n ^p3 is an integer from 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, multiple R ^p2 are the same or different from each other. When ^np2 is 2 or more, the multiple ^Rp3 are the same or different from each other, and the multiple ^Rp4 are the same or different from each other. When ^np3 is 2 or more, the multiple ^Rp5 are the same or different from each other, and the multiple ^Rp6 are the same or different from each other. T ⁺ is a monovalent radiation-sensitive onium cation.

Examples of the monovalent group containing a ring structure having 5 or more ring members, represented by R ^p1 , include a monovalent group containing an alicyclic structure having 5 or more ring members, a monovalent group containing an aliphatic heterocyclic structure having 5 or more ring members, a monovalent group containing an aromatic carbon ring structure having 5 or more ring members, and a monovalent group containing an aromatic heterocyclic structure having 5 or more ring members.

Examples of alicyclic structures having 5 or more ring members include monocyclic saturated alicyclic structures such as cyclopentane structure, cyclohexane structure, cycloheptane structure, cyclooctane structure, cyclononane structure, cyclodecane structure, and cyclododecane structure; monocyclic unsaturated alicyclic structures such as cyclopentene structure, cyclohexene structure, cycloheptene structure, cyclooctene structure, and cyclodecene structure; polycyclic saturated alicyclic structures such as norbornane structure, adamantane structure, tricyclodecane structure, and tetracyclododecane structure; and polycyclic unsaturated alicyclic structures such as norbornene structure and tricyclodecene structure.

Examples of aliphatic heterocyclic structures having 5 or more ring members include lactone structures such as a hexanolactone structure and a norbornanelactone structure, sultone structures such as a hexanosultone structure and a norbornanesultone structure, oxygen atom-containing heterocyclic structures such as an oxacycloheptane structure and an oxanorbornane structure, nitrogen atom-containing heterocyclic structures such as an azacyclohexane structure and a diazabicyclooctane structure, and sulfur atom-containing heterocyclic structures such as a thiacyclohexane structure and a thianorbornane structure.

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

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

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

A part or all of the hydrogen atoms 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, and acyloxy group. Among these, hydroxy group is preferred.

R ^p1 is preferably a monovalent group containing an alicyclic structure having 5 or more ring members or a monovalent group containing an aliphatic heterocyclic structure having 5 or more ring members, more preferably a monovalent group containing a polycyclic saturated alicyclic structure, a monovalent group containing an oxygen atom-containing heterocyclic structure or a monovalent group containing a nitrogen atom-containing heterocyclic structure, and still more preferably an adamantyl group, a norbornane sultonyl group or an azacyclohexylanyl group.

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, a divalent hydrocarbon group, etc. 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 even 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.

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

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

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

The lower limit of ^np1 + ^np2 + ^np3 is preferably 2, and more preferably 4. The upper limit of ^np1 + ^np2 + ^np3 is preferably 20, and more preferably 10.

Examples of the monovalent radiation-sensitive onium cation represented by T ⁺ include the cation represented by the following formula (ra) (hereinafter also referred to as "cation (ra)"), the following formula (r- The cation represented by b) (hereinafter also referred to as "cation (r-b)"), the cation represented by the following formula (r-c) (hereinafter also referred to as "cation (r-c)"), etc. Can be mentioned.

In the above 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 having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. When b3 is 2 or more, the plurality of R ^B5s are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom, or these groups are combined with each other. These represent a part of a ring structure with 4 to 20 ring members that is formed together with the carbon chains to which they are bonded. n _bb is an integer from 0 to 3.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ^B3 , R ^B4 and R ^B5 include groups similar to the organic group exemplified as R ¹² in formula (3) above.

R ^B3 and R ^B4 are preferably monovalent unsubstituted hydrocarbon groups having 1 to 20 carbon atoms or hydrocarbon groups in which a hydrogen atom is substituted with a substituent; An aromatic hydrocarbon group or an aromatic hydrocarbon group in which the hydrogen atom is substituted with a substituent is more preferable, a substituted or unsubstituted phenyl group is even more preferable, and an unsubstituted phenyl group is particularly preferable.

The substituent which may substitute a hydrogen atom of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^B3 and R ^B4 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 , -O-R ^kk -COOR ^k , -R ^kk -CO-R ^k or -S-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 having 1 to 10 carbon atoms.

R ^B5 is 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 , -O-R ^kk -COOR ^k , -R ^kk -CO-R ^k or -S-R ^k are preferred. R ^k is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ^kk is a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms.

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

The above R ^B6 and R ^B7 are substituted or unsubstituted monovalent hydrocarbon groups having 1 to 20 carbon atoms, -OR ^k , -COOR ^k , -O-CO-R ^k , -O-R ^kk -COOR ^k or -R ^kk -CO-R ^k is preferred. R ^k is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ^kk is a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms.

In the above formula (rc), b6 is an integer from 0 to 5. When b6 is 1, R ^B9 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. When b6 is 2 or more, the plurality of R ^B9s are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom, or these groups are combined with each other. These represent a part of a ring structure with 4 to 20 ring members that is formed together with the carbon chains to which they are bonded. b7 is an integer from 0 to 5. When b7 is 1, R ^B10 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. When b7 is 2 or more, the plurality of R ^B10s are the same or different and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom, or these groups are combined with each other. These represent a part of a ring structure with 4 to 20 ring members that is formed together with the carbon chains to which they are bonded.

The above R ^B9 and R ^B10 are 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 , -O-R ^kk -COOR ^k , -R ^kk -CO-R ^k , -S-R ^k or a ring structure formed by combining two or more of these groups. R ^k is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ^kk is a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms.

Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms represented by R ^B5 , R ^B6 , R ^B7 , R ^B9 and R ^B10 include methyl group, ethyl group, n-propyl group, n-butyl group, etc. Straight chain alkyl groups, i-propyl groups, i-butyl groups, sec-butyl groups, branched alkyl groups such as t-butyl groups, phenyl groups, tolyl groups, xylyl groups, mesityl groups, naphthyl groups, etc. Examples include aryl groups, benzyl groups, aralkyl groups such as phenethyl groups, and the like.

Examples of the divalent organic group represented by R ^B8 include groups in which one hydrogen atom has been removed from the monovalent organic groups having 1 to 20 carbon atoms exemplified as R ^B3 , R ^B4 and R ^B5 in the above formula (ra).

Examples of substituents that may substitute the hydrogen atoms of the hydrocarbon groups represented by R ^B5 , R ^B6 , R ^B7 , R ^B9 and R ^B10 include fluorine atom, chlorine atom, bromine atom, and iodine atom. Examples include halogen atoms such as hydroxy groups, carboxy groups, cyano groups, nitro groups, alkoxy groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, acyl groups, and acyloxy groups. Among these, halogen atoms are preferred, and fluorine atoms are more preferred.

R ^B5 , R ^B6 , R ^B7 , R ^B9 and R ^B10 are preferably an unsubstituted linear or branched monovalent alkyl group, a monovalent fluorinated alkyl group, an unsubstituted monovalent aromatic hydrocarbon group, -OSO ₂ -R ^k or -SO ₂ -R ^k , more preferably a fluorinated alkyl group or an unsubstituted monovalent aromatic hydrocarbon group, and even more preferably a fluorinated alkyl group.

In formula (r-a), b3 is preferably 0 to 2, more preferably 0 or 1, and even more preferably 0. In _formula (r-b), b4 is preferably 0 to 2, more preferably 0 or 1, and even more preferably 0. In formula (r-b), b5 is preferably 0 to 2, more preferably 0 or 1, and even more preferably 0. In formula (r-c), _b6 and _b7 are preferably 0 to 2, more preferably 0 or 1, and even more preferably 0.

Of these, T ⁺ is preferably the cation (ra), more preferably the triphenylsulfonium cation.

[B] Examples of the acid generator that generates sulfonic acid include compounds represented by the following formulas (5-1) to (5-5) (hereinafter also referred to as "compounds (5-1) to (5-5)").

In the above formulas (5-1) to (5-5), T ⁺ is a monovalent radiation-sensitive onium cation.

When the [B] acid generator is a [B] acid generator, the lower limit of the content of the [B] acid generator in the radiation-sensitive resin composition is based on 100 parts by mass of the [A] polymer. , is preferably 0.1 part by mass, more preferably 1 part by mass, and even more preferably 5 parts by mass. The upper limit of the content is preferably 70 parts by mass, more preferably 50 parts by mass, even more preferably 40 parts by mass, and particularly preferably 30 parts by mass. [B] By setting the content of the acid generator within the above range, the sensitivity to exposure light and LWR performance of the resist pattern formed by the radiation-sensitive resin composition can be further improved, and the process window can be widened. It can be further expanded.

<[C] Compound>
[C] The compound is a compound represented by the following formula (2). [C] The compound acts as an acid diffusion control agent. The acid diffusion control agent has the effect of controlling the diffusion phenomenon of acid generated from the [B] acid generator and the like in the resist film upon exposure, and controlling undesirable chemical reactions in non-exposed areas. By containing the [C] compound, the radiation-sensitive resin composition has good sensitivity to exposure light, excellent LWR performance, and can form a resist pattern with a wide process window.

In the above 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 combined with the carbon atoms to which they are bonded form a ring structure having 3 to 20 ring members. A ⁺ is a monovalent radiation-sensitive onium 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 as exemplified as R ¹² in the above formula (3).

A ring structure having 3 to 20 ring members formed by combining two or more of R ⁷ , R ⁸ and R ⁹ together with the carbon atom to which they are bonded includes, for example, an alicyclic structure having 3 to 20 ring members; Examples include aliphatic heterocyclic structures having 4 to 20 ring members, aromatic carbocyclic structures having 6 to 20 ring members, and aromatic heterocyclic structures having 6 to 20 ring members.

Examples of the alicyclic structure having 3 to 20 ring members, the aliphatic heterocyclic structure having 4 to 20 ring members, the aromatic carbocyclic structure having 6 to 20 ring members, and the aromatic heterocyclic structure having 6 to 20 ring members include ring structures similar to the aliphatic heterocyclic structure, aliphatic heterocyclic structure, aromatic carbocyclic structure, and aromatic heterocyclic structure exemplified as R ^p1 in the above formula (5).

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

At least one of R ⁷ , R ⁸ and R ⁹ is preferably a fluorine atom, more preferably two of them are fluorine atoms, and R ⁷ and R ⁹ are fluorine atoms. is even more preferable.

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 preferable. Examples of heteroatoms other than a fluorine atom include a nitrogen atom, an oxygen atom, and a sulfur atom, and an oxygen atom is preferable. R ⁸ is more preferably a monovalent organic group having 1 to 40 carbon atoms containing at least one selected from an ester structure, a ketone structure, and a hydroxyl group. R ⁸ is also preferably a monovalent organic group having 1 to 40 carbon atoms and having a ring structure. Examples of such ring structures include an alicyclic structure, an aromatic carbon ring structure, an aliphatic heterocyclic structure, and an aromatic heterocyclic structure, and specific ring structures are the same as those described above. Among them, an alicyclic structure is preferable as the ring structure, and a cycloalkyl ring and an adamantane ring are more preferable. Alternatively, R ⁸ is also preferably a monovalent organic group having 1 to 40 carbon atoms not containing a fluorine atom. It is particularly preferable that R ⁷ and R ⁹ are fluorine atoms, and R ⁸ is in such an embodiment.

As A ⁺ , the above cation (r-a), the above cationic formula (r-b) or the above cation (r-c) is preferable, the above cation (r-a) or the above cation (r-b) is more preferable, the above cation (r-a) is further preferable, and a triphenylsulfonium cation is particularly preferable.

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

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

As the [C] compound, the above compounds (2-1) to (2-7) are preferable.

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

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

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

Examples of alcohol-based solvents include aliphatic monoalcohol solvents having 1 to 18 carbon atoms, such as 4-methyl-2-pentanol and n-hexanol; alicyclic monoalcohol solvents having 3 to 18 carbon atoms, such as cyclohexanol; polyhydric alcohol solvents having 2 to 18 carbon atoms, such as 1,2-propylene glycol; and polyhydric alcohol partial ether solvents having 3 to 19 carbon atoms, such as propylene glycol-1-monomethyl ether.

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

Examples of ketone solvents include chain ketone solvents such as acetone, methyl ethyl ketone, methyl n-propyl ketone, methyl n-butyl ketone, diethyl ketone, methyl iso-butyl ketone, 2-heptanone, ethyl n-butyl ketone, 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, and acetophenone.

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

Examples of ester solvents include monocarboxylic acid ester solvents such as n-butyl acetate and ethyl lactate, lactone solvents such as gamma-butyrolactone and valerolactone, polyhydric alcohol carboxylate solvents such as propylene glycol acetate, polyhydric alcohol partial ether carboxylate solvents such as propylene glycol monomethyl ether acetate, polyvalent carboxylic acid diester solvents such as diethyl oxalate, and carbonate solvents such as dimethyl carbonate and diethyl carbonate.

Examples of hydrocarbon solvents include aliphatic hydrocarbon solvents with 5 to 12 carbon atoms, such as n-pentane and n-hexane, and aromatic hydrocarbon solvents with 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 polyhydric alcohol partial ether solvent having 3 to 19 carbon atoms or a polyhydric alcohol partial ether carboxylate solvent, propylene glycol-1- More preferred are monomethyl ether or propylene glycol acetate monomethyl ether. [D] The organic solvent may contain one type or two or more types.

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

<Other optional ingredients>
Examples of the other optional components include an acid diffusion controller other than the compound [C], a surfactant, etc. The radiation-sensitive resin composition may contain one or more types of each of the other optional components.

[Other acid diffusion controllers other than [C] compound]
In the radiation-sensitive resin composition, the content form of the acid diffusion control agent other than [C] compound includes the form of a low molecular compound (hereinafter also referred to as "other acid diffusion control agent"), [A] heavy Examples include a form incorporated as a part of a polymer, such as a combination, or a form of both.

Other examples of acid diffusion control agents include nitrogen atom-containing compounds and photodecomposable bases that are exposed to light and generate weak acids (excluding those that fall under the category of [C] compounds).

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

Examples of photodegradable bases include compounds containing onium cations and weak acid anions that decompose upon exposure to light (excluding those corresponding to [C] compounds).

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

[Surfactant]
The surfactant has the effect of improving the coating property, striation, developability, etc. Examples of the surfactant include nonionic surfactants such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, and polyethylene glycol distearate. Commercially available products include KP341 (Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, and Polyflow No. Examples of such products include EFTOP EF301, EF303, and EF352 (manufactured by Tochem Products Co., Ltd.), Megafac F171 and F173 (manufactured by DIC Corporation), Fluorad FC430 and FC431 (manufactured by Sumitomo 3M Limited), Asahiguard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, and SC-106 (manufactured by Asahi Glass Industry Co., Ltd.).

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 2 parts by mass per 100 parts by mass of the [A] polymer. is preferred. The lower limit of the content is, for example, 0.1 part by mass.

<Method for preparing radiation-sensitive resin composition>
The radiation-sensitive resin composition is prepared by mixing, for example, [A] polymer, [B] acid generator, [C] compound, and if necessary, [D] organic solvent and other optional components in a predetermined ratio. However, it can be prepared by preferably 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 both positive pattern formation using an alkaline developer and negative pattern formation using an organic solvent-containing developer.

The radiation-sensitive resin composition is for exposure by radiation (exposure light) irradiated in the exposure step of the resist pattern formation method described below. Among exposure lights, extreme ultraviolet light (EUV) or electron beams have relatively high energy, but the radiation-sensitive resin composition has good sensitivity to the exposure light, even when extreme ultraviolet light or electron beams are used as the exposure light, and can form a resist pattern that has excellent LWR performance and a wide process window. Therefore, the radiation-sensitive resin composition can be particularly suitably used for extreme ultraviolet light 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 the substrate (hereinafter also referred to as "coating step"), and exposing the resist film formed by the above coating step to light. (hereinafter also referred to as "exposure step"); and a step of developing the exposed resist film (hereinafter also referred to as "developing step").

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

Each step of the resist pattern formation method is described below.

[Coating process]
In this step, the radiation-sensitive resin composition is applied directly or indirectly to a substrate. This forms a resist film. Examples of the substrate include conventionally known substrates such as silicon wafers, silicon dioxide, and aluminum-coated wafers. In addition, an organic or inorganic anti-reflective film disclosed in, for example, JP-B-6-12452 or JP-A-59-93448 may be formed on the substrate as the underlayer film. Examples of the coating method include spin coating, casting coating, and roll coating. After coating, pre-baking (PB) may be performed as necessary to volatilize the solvent in the coating film. The lower limit of the PB temperature is preferably 60° C., and more preferably 80° C. The upper limit of the temperature is preferably 150° C., and more preferably 140° C. The lower limit of the PB time is preferably 5 seconds, and more preferably 10 seconds. The lower limit of the time is preferably 600 seconds, and more preferably 300 seconds. The lower limit of the average thickness of the resist film formed is preferably 10 nm, more preferably 20 nm, and the upper limit of the average thickness is preferably 1,000 nm, more preferably 500 nm.

[Exposure process]
In this step, the resist film formed in the above coating step is exposed. This exposure is performed by irradiating exposure light through a photomask (in some cases, through an immersion medium such as water). The exposure light can be electromagnetic waves such as visible light, ultraviolet rays, far ultraviolet rays, extreme ultraviolet rays (EUV), X-rays, and γ-rays; charged particles such as electron beams and α-rays, depending on the line width of the target pattern, etc. Examples include lines. Among these, far ultraviolet rays, EUV or electron beams are preferable, ArF excimer laser beams (wavelength 193 nm), KrF excimer laser beams (wavelength 248 nm), EUV or electron beams are more preferable, and ArF excimer laser beams, EUV or electron beams are preferable. More preferred is EUV or electron beam. The exposure conditions such as the exposure amount can be appropriately selected depending on the composition of the radiation-sensitive resin composition, the type of additive, the type of exposure light, and the like.

After the exposure, it is preferable to perform a post-exposure bake (PEB) to promote dissociation of the acid-dissociable group of the polymer [A] by the acid generated from the acid generator [B] by exposure in the exposed portion of the resist film. This PEB can increase the difference in solubility in the developer between the exposed portion and the unexposed portion. The lower limit of the PEB temperature is preferably 50°C, more preferably 80°C, and even more preferably 90°C. The upper limit of the temperature is preferably 180°C, and more preferably 130°C. The lower limit of the PEB time is preferably 5 seconds, more preferably 10 seconds, and even more preferably 30 seconds. The upper limit of the time is preferably 600 seconds, more preferably 300 seconds, and even more preferably 100 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 a rinsing liquid such as water or alcohol and dry. The developing method in the developing step may be alkaline development or organic solvent development.

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

In the case of organic solvent development, examples of the developer include organic solvents such as hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, and alcohol solvents, and solvents containing the above organic solvents. Examples of the organic solvent include one or more of the solvents exemplified as the organic solvent [D] of the radiation-sensitive resin composition described above. Among these, ester solvents or ketone solvents are preferred. As the ester solvent, acetate ester solvents are 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 content of the organic solvent in the developer is preferably 80% by mass, more preferably 90% by mass, even more preferably 95% by mass, and particularly preferably 99% by mass. Examples of components other than the organic solvent in the developer include water and silicone oil.

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

Examples of patterns formed by this resist pattern formation method include line and space patterns, hole patterns, etc.

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

[Weight average molecular weight (Mw), number average molecular weight (Mn) and dispersity (Mw/Mn)]
The Mw and Mn of the polymer were measured by gel permeation chromatography (GPC) using GPC columns (two "G2000HXL", one "G3000HXL", and one "G4000HXL" from Tosoh Corporation) under the following conditions. The dispersity (Mw/Mn) was calculated from the measurement results of Mw and Mn.

Elution solvent: tetrahydrofuran Flow rate: 1.0 mL/min Sample concentration: 1.0 mass%
Sample injection volume: 100 μL
Column temperature: 40°C
Detector: Differential refractometer Standard material: Monodisperse polystyrene

[Content of each structural unit of 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-Delta400" manufactured by JEOL Ltd.).

<[A] Synthesis of polymer>
The monomers used in the synthesis of each polymer in each Example and Comparative Example are shown below. In addition, in the following synthesis examples, unless otherwise specified, parts by mass mean the values when the total mass of the monomers used is 100 parts by mass, and mol% means the total number of moles of the monomers used. It means the value when it is taken as 100 mol%.

Synthesis Example 1: Synthesis of Polymer (A-1) Monomer (M-1), monomer (M-3) and monomer (M-10) were dissolved in propylene glycol-1-monomethyl ether (200 parts by mass) so that the molar ratio was 40/40/20 (mol%), and AIBN (6 mol%) was added as an initiator to prepare a monomer solution. Propylene glycol-1-monomethyl ether (100 parts by mass) was placed in an empty reaction vessel and heated to 85°C with stirring. Next, the monomer solution was dropped into the reaction vessel over 3 hours, and further heated at 85°C for 3 hours. The polymerization reaction was carried out for a total of 6 hours, with the start of the drop of the monomer solution being the start time of the polymerization reaction. After the polymerization reaction was completed, the polymerization solution was cooled to room temperature. The cooled polymerization solution was poured into hexane (500 parts by mass relative to 100 parts by mass of the polymerization solution), and the precipitated white powder was filtered off. The filtered white powder was washed twice with hexane (100 parts by mass relative to 100 parts by mass of the polymerization solution), filtered, 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 the hydrolysis reaction was carried out 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 dropped into 500 parts by mass of water to coagulate the resin, and the obtained solid was filtered and dried at 50 ° C. for 12 hours to obtain a white powdery polymer (A-1). The Mw of the polymer (A-1) was 5600, and the Mw / Mn was 1.62. As a result of ¹³ C-NMR analysis, the contents of the structural units derived from (M-1), (M-3) and (M-10) were 42.3 mol %, 39.8 mol % and 17.9 mol %, respectively.

[Synthesis Examples 2 to 8] Synthesis of Polymers (A-2) to (A-8) Polymers (A-2) to (A-8) were synthesized in the same manner as in Synthesis Example 1, except that the types and blending ratios of monomers shown in Table 1 below were used. The content ratios of each structural unit and physical properties (Mw and Mw/Mn) of the obtained polymers are also shown in Table 1 below. In Table 1 below, "-" indicates that the corresponding monomer was not used.

[Synthesis Example 9] Synthesis of Polymer (A-9) Using monomers of the type and blending ratio shown in Table 1 below, "Polymer (B-3-1)" described in JP-A No. 2009-244805 was synthesized. Polymer (A-9) was synthesized by a method similar to that of . The content ratio and physical property values (Mw and Mw/Mn) of each structural unit of the obtained polymer are shown in Table 1 below.

<Preparation of Radiation-Sensitive Resin Composition>
The components other than the polymer [A] used in the preparation of the radiation-sensitive resin composition are shown below. In the following examples and comparative examples, unless otherwise specified, parts by mass refer to a value when the mass of the polymer used is taken as 100 parts by mass, and mol % refers to a value when the number of moles of the acid generator [B] used is taken as 100 mol %.

[[B] Acid Generator]
B-1 to B-4: Compounds represented by the following formulas (B-1) to (B-4)

[[C] Acid diffusion control agent]
C-1 to C-9: Compounds represented by the following formulas (C-1) to (C-9)

[D] Organic Solvents
D-1: Propylene glycol monomethyl ether acetate D-2: Propylene glycol-1-monomethyl ether

[Example 1]
A radiation-sensitive resin composition (R-1) was prepared by mixing 100 parts by mass of (A-1) as a polymer [A], 20 parts by mass of (B-1) as an acid generator [B], 20 mol% of (C-1) as an acid diffusion controller [C], 4,800 parts by mass of (D-1) as an organic solvent [D], and 2,000 parts by mass of (D-2). The mixture was filtered through a membrane filter having a pore size of 0.2 μm.

[Examples 2 to 14 and Comparative Examples 1 to 3]
Radiation-sensitive resin compositions (R-2) to (R-14) and (CR-1) to (CR-3) was prepared.

<Formation of Resist Pattern (EUV Exposure, Alkaline Development)>
The radiation-sensitive resin composition prepared above was applied onto the underlayer film of a 12-inch silicon wafer having an average thickness of 20 nm (Brewer Science's "AL412") using a spin coater (Tokyo Electron Co., Ltd.'s "CLEAN TRACK ACT12"), and soft baked (SB) at 130°C for 60 seconds. Thereafter, the resist film was cooled at 23°C for 30 seconds to form a resist film having an average thickness of 50 nm. Next, the resist film was exposed to light using an EUV exposure device (ASML's "NEX3300") with NA = 0.33, illumination conditions: Conventional s = 0.89, and mask: imecDEFECT32FFR02. After exposure, the resist film was developed for 30 seconds at 23°C using a 2.38 mass% TMAH solution as an alkaline developer to form a positive resist pattern (32 nm line and space pattern).

<Evaluation>
The resist patterns thus formed were evaluated for sensitivity, LWR performance, and process window according to the following methods. A scanning electron microscope (CG-4100, Hitachi High-Technologies Corporation) was used to measure the length of the resist patterns. The evaluation results are shown in Table 3 below. Note that "-" in Table 3 below indicates that in Comparative Example 2, even the unexposed areas were dissolved in the alkaline developer, so that no resist pattern was formed and various evaluations could not be performed.

[sensitivity]
In forming the resist pattern, the exposure amount for forming a 32 nm line-and-space pattern was defined as the optimum exposure amount, and this optimum exposure amount was defined as the sensitivity (mJ/cm ² ). Sensitivity can be evaluated as "good" if it is 30 mJ/cm ² or less, and "poor" if it exceeds 30 mJ/cm ² .

[LWR performance]
The resist pattern formed above was observed from above the resist pattern using the scanning electron microscope. The line width was measured at a total of 50 points at arbitrary locations, a 3 sigma value was determined from the distribution of the measured values, and this 3 sigma value was defined as LWR (nm). The smaller the value of LWR, the less wobbling the line is, indicating that it is better. The LWR performance can be evaluated as "good" if it is 4.0 nm or less, and "poor" if it exceeds 4.0 nm.

[Process Window]
The "process window" refers to the range of resist dimensions that can form a pattern without bridge defects or collapse. Patterns from low to high exposure doses were formed using a mask that forms a 32 nm line and space pattern (1L/1S). In general, defects such as bridge formation between patterns are observed in the case of low exposure doses, and defects such as pattern collapse are observed in the case of high exposure doses. The difference between the maximum and minimum resist dimensions where these defects are not observed was defined as the "CD (Critical Dimension) margin." The larger the CD margin value, 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 "bad."

As is clear from the results in Table 3, the radiation-sensitive resin compositions of Examples had better sensitivity, LWR performance, and CD margin than the radiation-sensitive resin compositions of Comparative Examples.

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

Claims (6)

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 structural unit including an acid dissociable group:
A radiation-sensitive acid generator;
A radiation-sensitive resin composition comprising 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 monovalent fluorinated hydrocarbon group having 1 to 10 carbon atoms, provided that 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. * indicates a bonding site to a portion other than the group represented by 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 having 1 to 40 carbon atoms containing at least one structure selected from an ester structure and a ketone structure, and A ⁺ is a monovalent radiation-sensitive onium cation.) The radiation-sensitive resin composition according to claim 1, wherein the content of the third structural unit in the polymer is 30 mol % or more and 80 mol % or less of all 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, 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 hydrogen atoms on (p+q+1) aromatic rings from an arene having 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, multiple R ¹² are the same or different and are a monovalent organic group having 1 to 20 carbon atoms or a halogen atom, or two or more of the multiple R ¹² are combined with each other to form a part of a ring structure having 4 to 20 ring members together with the carbon chain to which they are bonded. q is an integer from 1 to 11. However, p+q is 11 or less.) Claim 1, wherein the third structural unit is represented by the following formula (4-1A), formula (4-1B), formula (4-1C), formula (4-2A), or formula (4-2B). radiation-sensitive resin composition.

(In formulas (4-1A), (4-1B), (4-1C), (4-2A) and (4-2B), R ^T is each independently a hydrogen atom, a fluorine atom, a methyl group Or a trifluoromethyl group.
In formulas (4-1A) and (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 having 1 to 20 carbon atoms, or a ring formed by combining R ^Y and R ^Z together with the carbon atom to which they are bonded. It is part of an alicyclic structure with 3 to 20 members.
In formula (4-1C), R ^C is a hydrogen atom. R ^D and R ^E each independently represent a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^F is a divalent hydrocarbon group having 1 to 20 carbon atoms that constitutes an unsaturated alicyclic structure having 4 to 20 ring members together with the carbon atoms to which R ^C , R ^D and R ^E are bonded, respectively.
In formulas (4-2A) and (4-2B), R ^U and R ^V are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R ^W is each independently and is a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a part of an alicyclic structure having 3 to 20 ring members formed by combining R ^U and R ^V together with the carbon atoms to which they are bonded. or is part of an aliphatic heterocyclic structure having 5 to 20 ring members formed by combining R ^U and R ^W together with the carbon atom to which R ^U is bonded and the oxygen atom to which R ^W is bonded. ) The radiation-sensitive resin composition according to claim 1, which is for use in extreme ultraviolet exposure or electron beam exposure. A step of directly or indirectly applying the radiation-sensitive resin composition according to any one of claims 1 to 5 to a substrate;
a step of exposing the resist film formed by the coating step;
and developing the resist film after the exposure step.