JP2023108593A - Radiation-sensitive resin composition, resist pattern forming method, and compound - Google Patents

Abstract

To provide a radiation-sensitive resin composition, a resist pattern forming method, and a compound which are capable of forming a resist pattern good in sensitivity to exposure light and excellent in CDU performance and resolution.SOLUTION: The radiation-sensitive resin composition contains: a polymer whose solubility in a developer changes by the action of an acid; a radiation-sensitive acid generator; and a compound represented by the following formula (1).SELECTED DRAWING: None

Description

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

Radiation-sensitive resin compositions used for microfabrication by lithography include 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) and the like. Irradiation with radiation such as electromagnetic waves and charged particle beams such as electron beams generates acid in the exposed area, and a chemical reaction catalyzed by this acid causes a difference in the dissolution rate in the developer between the exposed area and the non-exposed area. Thus, a resist pattern is formed on the substrate.

Radiation-sensitive resin compositions are required to have good sensitivity to exposure light such as extreme ultraviolet rays and electron beams, as well as excellent CDU (Critical Dimension Uniformity) performance and resolution.

In response to these demands, the types and molecular structures of polymers, acid generators and other components used in radiation-sensitive resin compositions have been studied, and their combinations have also been studied in detail (especially See JP-A-2010-134279, JP-A-2014-224984 and JP-A-2016-047815).

JP 2010-134279 A JP 2014-224984 A JP 2016-047815 A

With the further miniaturization of resist patterns, the required level of the above performance has been further increased, and a radiation-sensitive resin composition that satisfies these requirements is desired.

The present invention has been made based on the circumstances as described above, and an object of the present invention is to provide a radiation-sensitive resist pattern having good sensitivity to exposure light and excellent CDU performance and resolution. An object of the present invention is to provide a resin composition, a method for forming a resist pattern, and a compound.

（式（１）中、Ａｒ^１は、環員数６～３０の芳香族炭化水素環から（ａ＋ｂ＋２）個の水素原子を除いた基である。Ｒ^１は、炭素数１～２０の１価の有機基又はハロゲン原子である。Ｌ^１は、２価の連結基である。Ｒ^２は、置換又は非置換の炭素数６～２０の１価の芳香族炭化水素基である。ａは、０～１０の整数である。ｂは、１～１０の整数である。但し、ａ＋ｂは１０以下である。ａが２以上の場合、複数のＲ^１は互いに同一又は異なる。ｂが２以上の場合、複数のＬ^１は互いに同一又は異なり、複数のＲ^２は互いに同一又は異なる。Ｘ^＋は、１価の感放射線性オニウムカチオンである。） The inventions made to solve the above problems are a polymer whose solubility in a developer is changed by the action of acid (hereinafter also referred to as "[A] polymer") and a radiation-sensitive acid generator (hereinafter referred to as It is a radiation-sensitive resin composition containing a "[C] acid generator") and a compound represented by the following formula (1) (hereinafter also referred to as a "[D] compound").

(In formula (1), Ar ¹ is a group obtained by removing (a + b + 2) hydrogen atoms from an aromatic hydrocarbon ring having 6 to 30 ring members. ^{R 1} is a monovalent an organic group or a halogen atom, L ¹ is a divalent linking group, R ² is a substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, a is 0 is an integer of up to 10. b is an integer of 1 to 10, provided that a+b is 10 or less, when a is 2 or more, a plurality of R ¹ are the same or different, and when b is 2 or more , a plurality of L ¹ are the same or different, a plurality of R ² are the same or different, and ^{X +} is a monovalent radiation-sensitive onium cation.)

Another invention made to solve the above problems is a step of directly or indirectly coating a substrate with the above-described radiation-sensitive resin composition, and a step of exposing the resist film formed by the coating step. and developing the exposed resist film.

Yet another invention made to solve the above problems is the [D] compound.

According to the radiation-sensitive resin composition and resist pattern forming method of the present invention, a resist pattern having good sensitivity to exposure light and excellent CDU performance and resolution can be formed. The compound of the present invention can be suitably used as a component of the radiation-sensitive resin composition. Therefore, these materials can be suitably used in the processing of semiconductor devices, which are expected to further miniaturize in the future.

The radiation-sensitive resin composition, resist pattern forming method and compound of the present invention are described in detail below.

<Radiation sensitive resin composition>
The radiation-sensitive resin composition contains [A] polymer, [C] acid generator, and [D] compound. The radiation-sensitive resin composition usually contains an organic solvent (hereinafter also referred to as "[E] organic solvent"). The radiation-sensitive resin composition may contain, as a preferred component, a polymer having a higher fluorine atom content than the [A] polymer (hereinafter also referred to as "[B] polymer"). The radiation-sensitive resin composition may contain other optional components as long as the effects of the present invention are not impaired.

The radiation-sensitive resin composition contains [A] polymer, [C] acid generator, and [D] compound, so that it has good sensitivity to exposure light, CDU performance and resolution. It is possible to form a resist pattern excellent in Although the reason why the radiation-sensitive resin composition having the above structure produces the above effects is not necessarily clear, it can be inferred, for example, as follows. That is, since the [D] compound has a bulky (bulky) structure, the diffusion length of the acid generated by exposure can be appropriately shortened, and as a result, sensitivity to exposure light, CDU performance and resolution are improved. can be improved.

The radiation-sensitive resin composition includes, for example, [A] polymer, [C] acid generator and [D] compound, and optionally [B] polymer, [E] organic solvent and other optional components. are mixed in a predetermined proportion, and the resulting mixture is preferably filtered through a membrane filter having a pore size of 0.20 μm or less.

Each component contained in the radiation-sensitive resin composition will be described below.

<[A] Polymer>
The [A] polymer is a polymer whose solubility in a developer changes under the action of acid. Usually, the [A] polymer has an acid-dissociable group, so that the property that the solubility in a developing solution is changed by the action of an acid is exhibited. Therefore, the [A] polymer preferably has a structural unit containing an acid-labile group (hereinafter also referred to as "structural unit (I)"). The radiation-sensitive resin composition may contain one or more [A] polymers.

[A] The polymer preferably further has a structural unit containing a phenolic hydroxyl group (hereinafter also referred to as "structural unit (II)"). [A] The polymer may further have structural units other than the structural units (I) and (II) (hereinafter also simply referred to as "other structural units"). [A] The polymer can have one or more structural units.

The lower limit of the content of the [A] polymer in the radiation-sensitive resin composition is preferably 50% by mass with respect to all components other than the [E] organic solvent contained in the radiation-sensitive resin composition. 70% by mass is more preferred, and 80% by mass is even more preferred. The upper limit of the content ratio is preferably 99% by mass, more preferably 95% by mass.

[A] The lower limit of the polystyrene equivalent weight average molecular weight (Mw) of the polymer measured by gel permeation chromatography (GPC) is preferably 1,000, more preferably 3,000, and even more preferably 4,000. The upper limit of Mw is preferably 50,000, more preferably 30,000, even more preferably 20,000, even more preferably 15,000, and particularly preferably 10,000. [A] By setting the Mw of the polymer within the above range, the coatability of the radiation-sensitive resin composition can be improved. [A] The Mw of the polymer can be adjusted, for example, by adjusting the type and amount of the polymerization initiator used in the synthesis.

[A] The upper limit of the ratio of Mw to the polystyrene equivalent number average molecular weight (Mn) of the polymer by GPC (hereinafter also referred to as "dispersity" or "Mw/Mn") is preferably 2.5, and 2.0. is more preferred, and 1.7 is even more preferred. The lower limit of the ratio is usually 1.0, preferably 1.1, more preferably 1.2, and even more preferably 1.3.

[Method for measuring Mw and Mn]
The Mw and Mn of the polymer herein are values measured using gel permeation chromatography (GPC) under the following conditions.
GPC column: 2 "G2000HXL", 1 "G3000HXL" and 1 "G4000HXL" manufactured by Tosoh Corporation Column temperature: 40°C
Elution solvent: Tetrahydrofuran Flow rate: 1.0 mL/min Sample concentration: 1.0% by mass
Sample injection volume: 100 μL
Detector: Differential refractometer Standard material: Monodisperse polystyrene

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

Each structural unit contained in the [A] polymer is described below.

[Structural unit (I)]
Structural unit (I) is a structural unit containing an acid-labile group. The term "acid-dissociable group" means a group that substitutes a hydrogen atom in a carboxy group, a hydroxy group or the like, and is dissociated by the action of an acid to give a carboxy group, a hydroxy group or the like. The acid dissociable group is dissociated by the action of the acid generated from the [C] acid generator or the like upon exposure, and a difference occurs in the solubility of the [A] polymer in the developer between the exposed area and the non-exposed area. Thereby, a resist pattern can be formed. [A] The polymer can have one or more structural units (I).

Examples of the structural unit (I) include structural units represented by the following formulas (2-1) and (2-2).

In formulas (2-1) and (2-2) above, R ³ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. Z is an acid-labile group (hereinafter also referred to as "acid-labile group (Z)").

In formula (2-2) above, L ² is a single bond, -COO-, -CONH- or -O-. Ar ² is a group obtained by removing (s+t+u+1) hydrogen atoms from an aromatic hydrocarbon ring having 6 to 20 ring members. s is an integer from 0-10 and t is an integer from 0-10. However, s+t is an integer of 1-10. When s is 2 or more, multiple Zs are the same or different. When s is 1 or more, R ⁴ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. When t is 2 or more, multiple R ⁴ are the same or different. When s is 0 and t is 1, ^R4 is an acid labile group. When s is 0 and t is 2 or more, at least one of the plurality of R ⁴ is an acid-labile group. R ⁵ is a monovalent organic group having 1 to 20 carbon atoms or a halogen atom. u is an integer from 0 to 10; When u is 2 or more, the plurality of ^R5 are the same or different. However, s + t + u is 10 or less

The term "number of ring members" refers to the number of atoms forming a ring structure, and in the case of a polycyclic ring, the number of atoms forming the polycyclic ring. "Aromatic ring" includes "aromatic hydrocarbon ring" and "aromatic heterocyclic ring". "Aromatic ring" includes "monocyclic aromatic ring" and "polycyclic aromatic ring". A “polycyclic aromatic ring” includes condensed polycyclic rings in which the two rings have two shared atoms, as well as polycyclic ring assemblies in which two rings have no shared atoms and are connected by a single bond. is also included.

"Carbon number" refers to the number of carbon atoms that constitute a group. "Organic group" refers to a group containing at least one carbon atom. A "hydrocarbon group" includes a chain hydrocarbon group, an alicyclic hydrocarbon group and an aromatic hydrocarbon group. This "hydrocarbon group" may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. The term "chain hydrocarbon group" refers to a hydrocarbon group that does not contain a cyclic structure and is composed only of a chain structure, and includes both linear hydrocarbon groups and branched hydrocarbon groups. The term "alicyclic hydrocarbon group" refers to a hydrocarbon group containing only an alicyclic ring as a ring structure and not containing an aromatic ring, and includes monocyclic alicyclic hydrocarbon groups and polycyclic alicyclic hydrocarbon groups. both groups. However, it is not necessary to consist only of an alicyclic ring, and a part thereof may contain a chain structure. An "aromatic hydrocarbon group" refers to a hydrocarbon group containing an aromatic ring as a ring structure. However, it is not necessary to consist only of an aromatic ring, and a part thereof may contain a chain structure or an alicyclic ring. An "aliphatic hydrocarbon group" refers to a chain hydrocarbon group and an alicyclic hydrocarbon group.

R ³ is preferably a hydrogen atom or a methyl group, more preferably a hydrogen atom, from the viewpoint of copolymerizability of the monomer that gives the structural unit (I).

^L2 is preferably a single bond.

Examples of aromatic hydrocarbon rings having 6 to 20 ring members that give Ar ² include benzene ring; condensed polycyclic aromatic hydrocarbon rings such as naphthalene ring, phenanthrene ring, anthracene ring and fluorene ring; biphenyl ring and terphenyl ring, binaphthalene ring, ring assembly type aromatic hydrocarbon ring such as phenylnaphthalene ring, and the like.

A benzene ring is preferable as the aromatic hydrocarbon ring having 6 to 20 ring members that gives Ar ² .

s is preferably 0 to 3, more preferably 0 to 2, and even more preferably 1.

When s is 1 or more, the monovalent organic group having 1 to 20 carbon atoms represented by R ⁴ includes, for example, a monovalent hydrocarbon group having 1 to 20 carbon atoms, and a carbon-carbon bond of this hydrocarbon group. A group (α) containing a divalent heteroatom-containing group therebetween, a group (β) in which some or all of the hydrogen atoms of the hydrocarbon group or the group (α) are substituted with a monovalent heteroatom-containing group , the above hydrocarbon group, the above group (α), or a group (γ) obtained by combining the above group (β) with a divalent heteroatom-containing group, and the like. Further, the organic group in this case may be an acid dissociable group (Z) described later.

Examples of monovalent hydrocarbon groups 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 6 carbon atoms. to 20 monovalent aromatic hydrocarbon groups and the like.

Examples of monovalent chain hydrocarbon groups 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. , an ethynyl group, a propynyl group, and an alkynyl group such as a butynyl group.

Examples of monovalent alicyclic hydrocarbon groups having 3 to 20 carbon atoms include monocyclic saturated alicyclic hydrocarbon groups such as cyclopentyl group and cyclohexyl group, norbornyl group, adamantyl group, tricyclodecyl group, tetracyclo Polycyclic alicyclic saturated hydrocarbon groups such as dodecyl group, monocyclic alicyclic unsaturated hydrocarbon groups such as cyclopentenyl group and cyclohexenyl group, norbornenyl group, tricyclodecenyl group, tetracyclodode Examples include polycyclic alicyclic unsaturated hydrocarbon groups such as senyl group.

Examples of monovalent aromatic hydrocarbon groups 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. and aralkyl groups such as groups.

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

Examples of divalent heteroatom-containing groups include -O-, -CO-, -S-, -CS-, -NR'-, and groups in which two or more of these are combined (e.g., -COO-, -CONR'-, etc.). R' is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. As the monovalent hydrocarbon group having 1 to 10 carbon atoms represented by R′, for example, those having 1 to 10 carbon atoms among the groups exemplified as the above-mentioned “monovalent hydrocarbon group having 1 to 20 carbon atoms” etc.

R ⁴ when s is 1 or more is preferably a monovalent organic group having 1 to 20 carbon atoms, and is a combination of a monovalent hydrocarbon group having 1 to 20 carbon atoms and a divalent heteroatom-containing group. A group is more preferable, a group obtained by combining a monovalent chain hydrocarbon group having 1 to 20 carbon atoms and -CO- is even more preferable, and an acyl group is even more preferable.

Examples of R ⁴ when s is 0 include groups similar to the acid dissociable group (Z) described later.

t is preferably 0 to 2, more preferably 1.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ⁵ include the same groups as those exemplified as the monovalent organic group having 1 to 20 carbon atoms represented by R ⁴ above. be done.

A halogen atom represented by ^R5 is a fluorine atom, a chlorine atom, a bromine atom or an iodine atom.

u is preferably 0 or 1, more preferably 0.

(Acid dissociable group (Z))
The acid-labile group (Z) is a group that substitutes for a hydrogen atom in a carboxy group, and is a group that dissociates under the action of an acid to give a carboxy group. Examples of the acid-dissociable group (Z) include groups represented by the following formulas (3-1) and (3-2).

In formula (3-1) above, R ^{1 X} is a substituted or unsubstituted 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 having 3 to It is part of twenty saturated alicyclic rings.

In formula (3-2) above, R ^A is a hydrogen atom. Each of R ^{1 B} and R 2 ^C is independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^D is a divalent hydrocarbon group having 1 to 20 carbon atoms forming an unsaturated alicyclic ring having 4 to 20 ring members together with the carbon atoms to which R ^A , R ^B and R ^C are respectively bonded.

Examples of monovalent hydrocarbon groups having 1 to 20 carbon atoms represented by R ^X , R ^Y , R ^Z , R ^B or R ^C include, for example, in the above formula (2-2), R ⁴ having 1 to Among the 20 monovalent organic groups, the same groups as those exemplified as the monovalent hydrocarbon groups having 1 to 20 carbon atoms can be mentioned.

Examples of substituents that the hydrocarbon group represented by R ^X above may have include halogen atoms such as a fluorine atom and an iodine atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an alkoxy group, an alkoxycarbonyl group, An alkoxycarbonyloxy group, an acyl group, an acyloxy group and the like can be mentioned.

The 3- to 20-membered saturated alicyclic ring in which R ^Y and R ^Z are combined together and formed together with the carbon atoms to which they are bonded include, for example, monocyclic rings such as cyclopropane ring, cyclobutane ring, cyclopentane ring and cyclohexane ring. Examples include polycyclic saturated alicyclic rings such as saturated alicyclic rings, norbornane rings, and adamantane rings.

As the divalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^D , for example, in the above formula (2-2), among the monovalent organic groups having 1 to 20 carbon atoms in R ⁴ , Examples include groups obtained by removing one hydrogen atom from the groups exemplified as the 1 to 20 monovalent hydrocarbon groups.

The 4- to 20-membered unsaturated alicyclic ring composed of R ^D and three carbon atoms to which R ^A , R ^B and R ^C respectively bond includes monocyclic rings such as cyclobutene ring, cyclopentene ring and cyclohexene ring. and polycyclic unsaturated alicyclic rings such as norbornene rings.

R ^X is preferably a substituted or unsubstituted chain hydrocarbon group or a substituted or unsubstituted aromatic hydrocarbon group, more preferably an unsubstituted chain hydrocarbon group or an unsubstituted aromatic hydrocarbon group, An unsubstituted alkyl group or an unsubstituted aryl group is more preferred, and a methyl group, ethyl group or phenyl group is even more preferred.

^RY is preferably a chain hydrocarbon group or an alicyclic hydrocarbon group, more preferably an alkyl group or polycyclic saturated alicyclic hydrocarbon group, and even more preferably a methyl group or a norbornyl group.

R ^Z is preferably a chain hydrocarbon group, more preferably an alkyl group, and even more preferably a methyl group.

R 2 ^Y and R ^{2 Z} are also preferably part of a saturated alicyclic ring having 3 to 20 ring members formed together with the carbon atoms to which they are combined. The saturated alicyclic ring is preferably a monocyclic saturated alicyclic ring, more preferably a cyclopentane ring or a cyclohexane ring.

Structural units (I) are preferably structural units represented by the following formulas (2-1-1) to (2-1-3) or (2-2-1).

In formulas (2-1-1) to (2-1-3) and (2-2-1) above, R ³ has the same definition as in formulas (2-1) to (2-2) above.

The lower limit of the content of the structural unit (I) in the [A] polymer is preferably 20 mol%, more preferably 25 mol%, and 30 mol% with respect to the total structural units constituting the [A] polymer. is more preferred, and 35 mol % is even more preferred. The upper limit of the content ratio is preferably 90 mol %, more preferably 80 mol %, and even more preferably 75 mol %. By setting the content of the structural unit (I) within the above range, the sensitivity to exposure light, CDU performance and resolution of the radiation-sensitive resin composition can be further improved. In addition, unless otherwise specified, the upper limit and lower limit of the numerical range in this specification may be "less than" or "less than", and the lower limit may be "more than" or "more than ' may be Also, the upper limit and the lower limit can be arbitrarily combined.

In some cases, the structural unit of the [A] polymer may be considered to overlap with two or more types of structural unit classification. For example, structural units that are considered applicable not only to structural unit (I) but also to structural units other than structural unit (I) may be included. To explain using a specific example, the structural unit represented by the following formula not only corresponds to structural unit (I) as "a structural unit having an acid-dissociable group", but also corresponds to "a structural unit having an alcoholic hydroxyl group" described later. It is also considered that the structural unit (III) also corresponds to the “structural unit containing”. In this specification, such a structural unit shall be treated as corresponding to the structural unit with the lower number in parentheses. That is, the structural unit represented by the following formula is treated as a structural unit (I) as a "structural unit having an acid-dissociable group" although it is a structural unit having an alcoholic hydroxyl group.

In the above formulas, R ³ has the same meaning as in formulas (2-1) and (2-2) above.

[Structural unit (II)]
Structural unit (II) is a group containing a phenolic hydroxyl group. The “phenolic hydroxyl group” refers not only to a hydroxy group directly attached to a benzene ring but also to general hydroxy groups directly attached to an aromatic ring. Structural unit (II) is a structural unit different from structural unit (I). Structural units containing both phenolic hydroxyl groups and acid-labile groups are classified as structural units (I). That is, structural unit (II) does not contain an acid-labile group. [A] The polymer may contain one or more structural units (II).

In the case of KrF exposure, EUV exposure, or electron beam exposure, the [A] polymer having the structural unit (II) can further increase the sensitivity of the radiation-sensitive resin composition to exposure light. Therefore, when the polymer [A] has the structural unit (II), the radiation-sensitive resin composition can be suitably used as a radiation-sensitive resin composition for KrF exposure, EUV exposure, or electron beam exposure. can be done.

Examples of the structural unit (II) include structural units represented by the following formulas (II-1) to (II-17) (hereinafter also referred to as "structural units (II-1) to (II-17)"), and the like. is mentioned.

In formulas (II-1) to (II-17) above, R ^{1 P} is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

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

The structural unit (II) includes structural units (II-1) to (II-3), (II-6) to (II-8), (II-11), (II-12), or combinations thereof. preferable.

When the [A] polymer has the structural unit (II), the lower limit of the content of the structural unit (II) in the [A] polymer is 15 per all structural units constituting the [A] polymer. mol % is preferred, 20 mol % is more preferred, and 25 mol % is even more preferred. The upper limit of the content ratio is preferably 60 mol %, more preferably 50 mol %, still more preferably 40 mol %, and particularly preferably 35 mol %.

[Other structural units]
Other structural units include a structural unit containing an alcoholic hydroxyl group (hereinafter also referred to as "structural unit (III)"), a structural unit containing an alkoxyalkyl group (hereinafter also referred to as "structural unit (IV)"), lactone structure, a cyclic carbonate structure, a sultone structure, or a structural unit containing a combination thereof (hereinafter also referred to as "structural unit (V)").

(Structural unit (III))
Structural unit (III) is a structural unit containing an alcoholic hydroxyl group. By further having the structural unit (III), the solubility in a developer can be more moderately adjusted.

Examples of the structural unit (III) include structural units represented by the following formula.

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

(Structural unit (IV))
Structural unit (IV) is a structural unit containing an alkoxyalkyl group. Adhesion to the substrate can be improved by further including the structural unit (IV).

Examples of the alkoxyalkyl group include groups obtained by combining an alkanediyl group having 2 to 5 carbon atoms, such as a methoxyethyl group and an ethoxyethyl group, with an alkoxy group having 1 to 5 carbon atoms. In other words, a group represented by —R ⁴¹ —OR ⁴² (R ⁴¹ is an alkanediyl group having 2 to 5 carbon atoms and R ⁴² is an alkyl group having 1 to 5 carbon atoms), etc. mentioned.

Examples of the structural unit (IV) include structural units represented by the following formula.

In the above formula, R ^L3 is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

When the [A] polymer 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 [A] polymer. preferable. The upper limit of the content ratio is preferably 30 mol %, more preferably 20 mol %.

<[B] Polymer>
The [B] polymer is a polymer different from the [A] polymer and has a higher fluorine atom content than the [A] polymer. Generally, a polymer having higher hydrophobicity than the base polymer tends to be unevenly distributed on the surface layer of the resist film. Since the [B] polymer has a higher fluorine atom content than the [A] polymer, it tends to be unevenly distributed on the surface layer of the resist film due to the characteristics resulting from this hydrophobicity. As a result, when the radiation-sensitive resin composition contains the [B] polymer, it is expected that the cross-sectional shape of the formed resist pattern will be good. The radiation-sensitive resin composition may contain the polymer [B] as a surface conditioner for resist films, for example. The radiation-sensitive resin composition may contain one or more [B] polymers.

<[C] acid generator>
[C] The acid generator is a substance that generates an acid upon exposure to light. Examples of the exposure light include those similar to those exemplified as the exposure light in the exposure step of the resist pattern forming method described later. The acid generated by exposure dissociates the acid dissociable group in the structural unit (I) of the polymer [A], causing a difference in solubility in the developer between the exposed and non-exposed areas of the resist film. Thereby, a resist pattern can be formed.

[C] Examples of the acid generated from the acid generator include sulfonic acid and imidic acid.

The [C] acid generator contained in the radiation-sensitive resin composition may be, for example, in the form of a low-molecular-weight compound (hereinafter also referred to as "[C] acid generator") described later, or may be a radiation-sensitive acid generator. It may be in the form of a generating polymer (hereinafter also referred to as "[C] acid-generating polymer") or in both of these forms. A "low-molecular weight compound" means a compound having a molecular weight of 1,000 or less that does not have a molecular weight distribution. A "radiation-sensitive acid-generating polymer" means a polymer having a structural unit that generates an acid upon exposure. In other words, the [C] acid-generating polymer can also be said to have a form in which the [C] acid-generating body is incorporated as a part of the polymer. The [C] acid-generating polymer may be a polymer different from the [A] polymer and [B] polymer. The radiation-sensitive resin composition may contain one or more [C] acid generators.

The [C] acid generator is preferably a [C] acid generator. [C] Acid generators include, for example, onium salt compounds, N-sulfonyloxyimide compounds, sulfonimide compounds, halogen-containing compounds, and diazoketone compounds.

Onium salt compounds include, for example, sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, pyridinium salts and the like.

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

As the [C] acid generator, a [C] acid generator that generates sulfonic acid upon exposure is preferred. Examples of [C] acid generators that generate sulfonic acid upon exposure include compounds represented by the following formula (4).

In formula (4) above, R ^a1 is a monovalent organic group having 1 to 30 carbon atoms. ^La is a divalent linking group. n _a1 is an integer from 0 to 10; When n _a1 is 2 or more, a plurality of L ^a are the same or different. R ^a2 and R ^a3 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. n _a2 is an integer of 0-10. When n _a2 is 2 or more, multiple R ^a2 are the same or different, and multiple R ^a3 are the same or different. Y ⁺ is a monovalent radiation-sensitive onium cation.

Examples of the monovalent organic group having 1 to 30 carbon atoms represented by R ^a1 include the monovalent organic groups having 1 to 20 carbon atoms represented by R ⁴ in the above formula (2-2). Examples thereof include the same groups as the valent organic groups.

The monovalent organic group having 1 to 30 carbon atoms represented by R ^a1 is preferably a monovalent group having 1 to 30 carbon atoms and containing a ring structure having 5 or more ring members. Examples of the ring structure having 5 or more ring members include an alicyclic ring having 5 or more ring members, an aliphatic heterocycle having 5 or more ring members, an aromatic hydrocarbon ring having 5 or more ring members, an aromatic heterocyclic ring having 5 or more ring members, or Combinations of these are included.

Some or all of the hydrogen atoms in the ring structure may be substituted with a substituent. Examples of substituents include halogen atoms such as fluorine atoms and iodine atoms, hydroxy groups, carboxy groups, cyano groups, nitro groups, alkyl groups, alkoxy groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, acyl groups, acyloxy groups, oxo group (=O) and the like.

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

Aliphatic heterocycles having 5 or more ring members include, for example, lactone structures such as hexanolactone ring and norbornane lactone ring; sultone structures such as hexanosultone ring and norbornane sultone ring; Examples include atom-containing heterocycles, nitrogen atom-containing heterocycles such as azacyclohexane ring and diazabicyclooctane ring, and sulfur atom-containing heterocycles such as thiacyclohexane ring and thianolbornane ring.

Examples of aromatic hydrocarbon rings having 5 or more ring members include benzene ring, naphthalene ring, phenanthrene ring, and anthracene ring.

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

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

Examples of the divalent linking group represented by L ^a include a carbonyl group, an ether group, a carbonyloxy group (-COO-), an oxycarbonyl group (-OCO-), a sulfide group, a thiocarbonyl group, a sulfonyl group, or Groups in which these are combined, and the like are included. Among these, an ether group, a carbonyloxy group or an oxycarbonyl group is preferred.

n _a1 is preferably 0 or 1.

As the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^a2 or R ^a3 , for example, in the above formula (2-2), among the monovalent organic groups having 1 to 20 carbon atoms for R ⁴ , the same groups as those exemplified as the monovalent hydrocarbon group having 1 to 20 carbon atoms, and the like.

As the monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms represented by R ^a2 or R ^a3 , for example, some or all of the hydrogen atoms in the above monovalent hydrocarbon group having 1 to 20 carbon atoms are fluorine Atom-substituted groups and the like are included.

R ^a2 and R ^a3 are preferably a hydrogen atom, a fluorine atom, an alkyl group or a fluorinated alkyl group, more preferably a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

n _a2 is preferably 0 to 5, more preferably 0 to 4.

Examples of the monovalent radiation-sensitive onium cation represented by Y ⁺ include monovalent cations represented by the following formulas (r−a) to (r−c) (hereinafter referred to as “cations (r−a) to (r−c)”) and the like.

In the above formula (ra), R ^{1 B1} and R ^{1 B2} are each independently a group obtained by removing one hydrogen atom from a substituted or unsubstituted 6-20 ring-membered aromatic hydrocarbon ring? , or R ^{1 B1} and R ^{1 B2} are part of a substituted or unsubstituted 9- to 30-membered polycyclic aromatic ring composed together with the sulfur atom to which they are attached. R ^B3 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group or a halogen atom. b1 is an integer from 0 to 9; When b1 is 2 or more, the plurality of R ^B3 are the same or different. _nb1 is an integer of 0-3.

In the above formula (rb), R ^{1 B4} and R ^{1 B5} are each independently a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group or a halogen atom. b2 is an integer from 0 to 9; When b2 is 2 or more, the plurality of R ^B4 are the same or different. b3 is an integer from 0 to 10; When b3 is 2 or more, the plurality of R ^B5 are the same or different. It is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group or a halogen atom. R ^B6 is a single bond or a divalent organic group having 1 to 20 carbon atoms. _nb2 is an integer from 0 to 2; _nb3 is an integer of 0-3.

In formula (rc) above, R ^{1 B7} and R ^{1 B8} are each independently a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group or a halogen atom. b4 is an integer from 0 to 5; When b4 is 2 or more, the plurality of R ^B7 are the same or different. b5 is an integer from 0 to 5; When b5 is 2 or more, the plurality of R ^B8 are the same or different.

Examples of the 6- to 20-membered aromatic hydrocarbon ring that gives R ^{1 B1} and R ^{2 B2} include the rings exemplified as the 6- to 20-membered aromatic hydrocarbon ring that gives Ar ² of the above formula (2-2). Similar rings and the like are included. The 6- to 20-membered aromatic hydrocarbon ring that gives R ^{1 B1} and R ^{2 B2} is preferably a benzene ring or a naphthalene ring, more preferably a benzene ring.

The 9- to 30-membered polycyclic aromatic ring in which R ^{1 B1} and R ^{2 B2} are combined and formed together with the sulfur atom to which they are bonded includes a benzothiophene ring, a dibenzothiophene ring, a thioxanthene ring, a thioxanthone ring, or a phenoxathi In-ring and the like are preferred.

In the above aromatic hydrocarbon ring and the above polycyclic aromatic ring, some or all of the hydrogen atoms bonded to the atoms constituting these ring structures may be substituted with substituents. Examples of substituents include halogen atoms such as fluorine atoms and iodine atoms, hydroxyl groups, carboxy groups, cyano groups, nitro groups, alkyl groups, fluorinated alkyl groups, alkoxy groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, and acyl groups. , an acyloxy group, an oxo group (=O), or a combination thereof. Among these, a fluorine atom, a hydroxy group, a trifluoromethyl group, a cyano group, a methyl group and a tert-butyl group are preferred.

Examples of monovalent organic groups having 1 to 20 carbon atoms represented by R ^B3 , R ^B4 , R ^B5 , R ^B7 and R ^B8 include 1 carbon atom represented by R ⁴ in formula (2-2) above. Examples include groups similar to the groups exemplified as monovalent organic groups of 1 to 20, and the like.

The divalent organic group represented by R ^B6 is, for example, one hydrogen atom selected from the groups exemplified as the monovalent organic group having 1 to 20 carbon atoms represented by R ⁴ in the above formula (2-2). and groups other than

b1 is preferably 0 to 2, more preferably 0 or 1, and still more preferably 0. As _nb1 , 0 or 1 is preferable.

The monovalent radiation-sensitive onium cation represented by Y ⁺ is preferably a cation (ra).

As the cation (ra), cations represented by the following formulas (ra-1) to (ra-13) are preferable.

[C] Acid generators are preferably compounds represented by the following formulas (4-1) to (4-10).

In formulas (4-1) to (4-10) above, Y ⁺ has the same meaning as in formula (4) above.

The lower limit of the content of the [C] acid generator in the radiation-sensitive resin composition is preferably 5 parts by mass, more preferably 10 parts by mass, and 15 parts by mass with respect to 100 parts by mass of the [A] polymer. is more preferred. The upper limit of the content is preferably 50 parts by mass, more preferably 40 parts by mass, and even more preferably 30 parts by mass. [C] By setting the content of the acid generator within the above range, the sensitivity to exposure light, CDU performance and resolution of the radiation-sensitive resin composition can be further improved.

<[D] compound>
The [D] compound is a compound represented by the following formula (1). The [D] compound acts as an acid diffusion control agent (quencher). The acid diffusion control agent controls the diffusion phenomenon in the resist film of the acid generated from the [C] acid generator or the like upon exposure, and controls undesirable chemical reactions (e.g., dissociation reaction of acid dissociable groups) in non-exposed regions. It is something to do. By containing the [D] compound, the radiation-sensitive resin composition has good sensitivity to exposure light and can form a resist pattern with excellent CDU performance and resolution.

In the above formula (1), Ar ¹ is a group obtained by removing (a+b+2) hydrogen atoms from an aromatic hydrocarbon ring having 6 to 30 ring members. R ¹ is a monovalent organic group having 1 to 20 carbon atoms or a halogen atom. L ¹ is a divalent linking group. R ² is a substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms. a is an integer from 0 to 10; b is an integer from 1 to 10; However, a+b is 10 or less. When a is 2 or more, the plurality of R ¹ are the same or different. When b is 2 or more, multiple ^L1 's are the same or different, and multiple ^R2 's are the same or different. X ⁺ is a monovalent radiation-sensitive onium cation.

Examples of the 6- to 30-membered aromatic hydrocarbon ring giving Ar ¹ include, for example, the same rings as those exemplified as the 6- to 20-membered aromatic hydrocarbon ring giving Ar ² in the above formula (2-2). etc. As the aromatic hydrocarbon ring having 6 to 30 ring members that gives Ar ¹ , a benzene ring or a naphthalene ring is preferable.

The carboxylate group (—COO ⁻ ) and the hydroxy group in the above formula (1) are preferably bonded to adjacent carbon atoms constituting Ar ¹ respectively. In other words, the carboxylate group and the hydroxy group are preferably attached to the same benzene ring in Ar ¹ at positions ortho to each other. In other words, it is preferred that the carbon atom on Ar ¹ to which the carboxylate group is attached and the carbon atom on Ar ¹ to which the hydroxy group is attached are directly connected. In this case, the storage stability of the radiation-sensitive resin composition can be improved.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ¹ include the groups exemplified as the monovalent organic groups having 1 to 20 carbon atoms represented by R ⁴ in the above formula (2-2). groups similar to and the like.

A halogen atom represented by R ¹ is a fluorine atom, a chlorine atom, a bromine atom or an iodine atom.

R ¹ is preferably a halogen atom, more preferably an iodine atom.

a is preferably 0 to 2, more preferably 0 or 1, and still more preferably 0.

Examples of the divalent linking group represented by L ¹ include an ether group (--O--), a carbonyloxy group (--CO--O--), an oxycarbonyl group (--O--CO--), a carbonyl sulfide group (-- CO—S—), a sulfide group (—S—), a thiocarbonyl group (—CS—), a sulfonyl group (—SO ₂ —), an alkanediyl group having 1 to 5 carbon atoms, or a combination thereof, and the like. be done.

L ¹ is preferably a carbonyloxy group, an oxycarbonyl group, an ether group, a sulfide group, an alkanediyl group having 1 to 5 carbon atoms, or a group consisting of a combination thereof, such as a carbonyloxy group, a methanediyloxy group (—CH ₂ — O—), a methanediylsulfide group (—CH ₂ —S—) or an oxycarbonylmethanediyloxy group (—O—CO—CH ₂ —O—) is more preferred.

Moreover, when combining the above divalent linking groups, it may be preferable not to combine groups of the same type. In other words, L ¹ is a carbonyloxy group, an oxycarbonyl group, an ether group, a sulfide group, an alkanediyl group having 1 to 5 carbon atoms, or a group combining these (provided that a combination of two or more groups of the same type is ) may be preferred. For example, the oxycarbonylmethanediyloxy group can also be regarded as a group in which two ether groups, a carbonyl group, and a methanediyl group are combined. However, the "carbonyl group" is not included in the divalent linking groups exemplified above. Therefore, it is regarded as a group obtained by combining an oxycarbonyl group, a methanediyl group and an ether group, and a combination of two or more groups of the same type is treated as not applicable. On the other hand, for example, an oxymethanediyloxy group (--O-- _CH.sub.2 --O--) is a group in which two ether groups are combined, so it is treated as a combination of two or more groups of the same type.

As the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms for R ² , for example, in the above formula (2-2), among the monovalent organic groups having 1 to 20 carbon atoms for R ⁴ , 6 carbon atoms Examples include the same groups as those exemplified as the monovalent aromatic hydrocarbon groups of 1 to 20, and the like.

R ² is preferably a substituted or unsubstituted aryl group, more preferably a substituted or unsubstituted phenyl group or a substituted or unsubstituted naphthyl group.

Examples of substituents that the aromatic hydrocarbon group represented by R ² may have include halogen atoms such as a fluorine atom and an iodine atom, a hydroxy group, a carboxy group, a cyano group, a nitro group, an alkoxy group, and an alkoxycarbonyl group. groups, alkoxycarbonyloxy groups, acyl groups, acyloxy groups, and the like. Among these, a fluorine atom, an iodine atom or an alkoxy group is preferable, and an iodine atom is more preferable.

R ² is more preferably a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms in which at least one hydrogen atom on the aromatic ring is replaced with an iodine atom. In this case, sensitivity to exposure light can be further improved.

Examples of the monovalent radiation-sensitive onium cation represented by X ⁺ include the monovalent radiation-sensitive onium cations exemplified as Y ⁺ in the above formula (4). X ⁺ is preferably the above cation (ra), more preferably cations (ra-1) to (ra-13).

Compounds [D] are preferably compounds represented by the following formulas (1-1) to (1-14).

In formulas (1-1) to (1-14) above, X ⁺ has the same meaning as in formula (1) above.

The lower limit of the content of the [D] compound in the radiation-sensitive resin composition is preferably 1 mol%, more preferably 5 mol%, and 10 mol% with respect to 100 mol% of the [C] acid generator. More preferred. The upper limit of the content ratio is preferably 200 mol %, more preferably 100 mol %, still more preferably 50 mol %, and particularly preferably 25 mol %. By setting the content of the compound [D] within the above range, the sensitivity to exposure light, CDU performance and resolution of the resist pattern formed from the radiation-sensitive resin composition can be further improved.

<[E] Organic solvent>
The radiation-sensitive resin composition usually contains [E] an organic solvent. The [E] organic solvent is particularly limited as long as it can dissolve or disperse at least the [A] polymer, [C] acid generator and [D] compound, and optionally other optional components. not.

[E] Organic solvents include, for example, alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, hydrocarbon solvents and the like. The radiation-sensitive resin composition may contain one or more [E] organic solvents.

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

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; diphenyl ether; Aromatic ring-containing ether solvents such as anisole are included.

Ketone solvents include, for example, 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, chain ketone solvents such as di-iso-butyl ketone and trimethylnonanone; cyclic ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone and methylcyclohexanone; 2,4-pentanedione and acetonylacetone , acetophenone, and the like.

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, N -methylacetamide, N,N-dimethylacetamide, chain amide solvents such as N-methylpropionamide, and the like.

Examples of ester solvents include monocarboxylic acid ester solvents such as n-butyl acetate and ethyl lactate, lactone solvents such as γ-butyrolactone and valerolactone, polyhydric alcohol carboxylate solvents such as propylene glycol acetate, and propylene acetate. Examples include polyhydric alcohol partial ether carboxylate solvents such as glycol monomethyl ether, 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 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. be done.

[E] The organic solvent is preferably an alcohol solvent, an ester solvent, or a combination thereof, and a polyhydric alcohol partial ether solvent having 3 to 19 carbon atoms, a polyhydric alcohol partial ether carboxylate solvent, or a combination thereof. More preferred are propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and combinations thereof.

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

<Other optional ingredients>
Other optional components include, for example, acid diffusion control agents other than the above [D] compound, surfactants, and the like. The radiation-sensitive resin composition may contain one or more other optional components.

<Resist pattern forming method>
The resist pattern forming method includes a step of directly or indirectly coating a substrate with a radiation-sensitive resin composition (hereinafter also referred to as a "coating step"), and exposing the resist film formed by the coating step. and a step of developing the exposed resist film (hereinafter also referred to as a “development step”).

According to the resist pattern forming method, by using the radiation-sensitive resin composition described above as the radiation-sensitive resin composition in the coating step, the sensitivity to exposure light is good, and the CDU performance and resolution are improved. It is possible to form a resist pattern excellent in

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

[Coating process]
In this step, the substrate is directly or indirectly coated with the radiation-sensitive resin composition. Thereby, a resist film is formed directly or indirectly on the substrate.

In this step, the radiation-sensitive resin composition described above is used as the radiation-sensitive resin composition.

Examples of the substrate include conventionally known substrates such as silicon wafers, silicon dioxide, and aluminum-coated wafers.

Examples of the coating method include spin coating, cast coating, roll coating, and the like. After coating, if necessary, prebaking (hereinafter also referred to as “PB”) may be performed in order to volatilize the solvent in the coating film. 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. The lower limit of the average thickness of the resist film to be formed 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 process]
In this step, the resist film formed in the 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 is preferably deep ultraviolet, EUV or electron beam, more preferably ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), EUV (wavelength 13.5 nm) or electron beam, KrF excimer laser Light, EUV or electron beams are more preferred, and EUV or electron beams are particularly preferred.

Post-exposure baking (hereinafter also referred to as “PEB”) is preferably performed after the exposure. This PEB can increase the difference in solubility in a developer between the exposed area and the non-exposed area. The lower limit of the PEB temperature is preferably 50°C, more preferably 80°C, and even more preferably 100°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 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. The developing method in the developing step may be alkali development or organic solvent development.

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

In the case of organic solvent development, the developer includes organic solvents such as hydrocarbon solvents, ether solvents, ester solvents, ketone solvents, alcohol solvents, and solutions containing the above organic solvents. Examples of the organic solvent include the solvents exemplified as the [D] organic solvent of the radiation-sensitive resin composition described above.

<Compound>
The compound is described as the [D] compound in the radiation-sensitive resin composition described above. The compound can be suitably used as a component of a radiation-sensitive resin composition. In addition, the compound can be suitably used as an acid diffusion controller.

EXAMPLES The present invention will be specifically described below based on Examples, but the present invention is not limited to these Examples. The method for measuring each physical property value is 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 according to the conditions described in the section [Method for measuring Mw and Mn] above. The dispersity (Mw/Mn) of the polymer was calculated from the measurement results of Mw and Mn.

<Synthesis of [D] compound>
[Synthesis Example 1-1] Synthesis of Compound (D-1) Sodium hydride (41.6 mmol) was dispersed in a container containing N,N-dimethylformamide (10 mL). A solution of 2,4-dihydroxybenzoic acid (10.0 mmol) in N,N-dimethylformamide (7.5 mL) was added dropwise to this vessel at room temperature over 1 hour. Then, a solution of 2-(bromomethyl)naphthalene (10.0 mmol) in N,N-dimethylformamide (7.5 mL) was added dropwise at room temperature over 1 hour. After the dropwise addition was completed, the mixture was further stirred at room temperature for 2 hours. After cooling to 10° C. or less, 1 mol/L hydrochloric acid (100 mL) was added to terminate the reaction. The precipitated solid was filtered, washed with distilled water and methylene chloride, respectively, and the compound represented by the following formula (pD-1) (2-hydroxy-4-((naphthalen-2-ylmethoxy)benzoic acid; hereinafter, " Compound (pD-1)” was obtained.

Compound (pD-1) (8.20 mmol), sodium hydrogen carbonate (16.4 mmol), triphenylsulfonium chloride (12.3 mmol), methylene chloride (82 mL) and distilled water (82 mmol) were mixed and incubated at room temperature for 3 hours. Stirred. After completion of the reaction, liquid separation was performed, and the organic layer was dried over anhydrous sodium sulfate and filtered. The solvent was distilled off to obtain a compound represented by the following formula (D-1) (hereinafter also referred to as “compound (D-1)”).

A synthesis scheme of compound (D-1) is shown below.

[Synthesis Examples 1-2 to 1-14] Synthesis of Compounds (D-2) to (D-14) In the same manner as in Synthesis Example 1, except that the precursors were appropriately selected, the following formulas (D-2) to Compounds represented by (D-14) (hereinafter also referred to as “compounds (D-2) to (D-14)”) were synthesized.

<[A] Synthesis of polymer>
[A] In the synthesis of the polymer, monomers represented by the following formulas (M-1) to (M-11) (hereinafter also referred to as "monomers (M-1) to (M-11)" ) was used. In the following synthesis examples, unless otherwise specified, "parts by mass" means the value when the total mass of the monomers used is 100 parts by mass, and "mol%" is the total amount of the monomers used. It means a value when the number of moles is 100 mol%.

[Synthesis Example 2-1] Synthesis of polymer (A-1) Monomer (M-1), monomer (M-5) and monomer (M-8) at a molar ratio of 45/45/ 10 by dissolving in propylene glycol-1-monomethyl ether (200 parts by mass). 7 mol % of 2,2'-azobis(methyl isobutyrate) was added as an initiator to prepare a monomer solution. On the other hand, propylene glycol monomethyl ether (100 parts by mass with respect to the total amount of monomers) was added to an empty container and heated to 85° C. while stirring. The above monomer solution was added dropwise to this container over 3 hours. After the addition was completed, the mixture was heated at 85° C. for 3 hours, and then cooled to room temperature. The polymer solution was dropped into n-hexane (1,000 parts by mass) to coagulate and purify the polymer.

The above polymer was added again to propylene glycol monomethyl ether (150 parts by mass) and dissolved. Methanol (150 parts by mass), triethylamine (1.5 molar equivalents relative to the amount of compound (M-1) used) and water (1.5 molar equivalents relative to the amount of compound (M-1) used) were added thereto. rice field. The hydrolysis reaction was carried out by refluxing at the boiling point for 8 hours. After completion of the reaction, the solvent and triethylamine were distilled off under reduced pressure, and the resulting polymer was dissolved in acetone (150 parts by mass). This was dropped into water (2,000 parts by mass) to solidify, and the resulting white powder was separated by filtration. After drying at 50° C. for 17 hours, a white powdery polymer (A-1) was obtained in good yield. Polymer (A-1) had an Mw of 7,200 and an Mw/Mn of 1.5.

[Synthesis Examples 2-2 to 2-8] Synthesis of Polymers (A-2) to (A-8) Same as in Synthesis Example 1 except that the types and proportions of monomers shown in Table 1 below were used. Then, polymers (A-2) to (A-8) were synthesized.

<[B] Polymer Synthesis>
[Synthesis Example 3-1] Synthesis of polymer (B-1) 2-butanone (100 mass part). 5 mol % of azobisisobutyronitrile was added as an initiator to prepare a monomer solution. On the other hand, 2-butanone (50 parts by mass) was placed in an empty container and purged with nitrogen for 30 minutes. The inside of the container was heated to 80° C., and the above monomer solution was added dropwise over 3 hours while stirring. After the addition was completed, the mixture was further heated at 80°C for 3 hours, and then cooled to 30°C or lower by water cooling. After the polymerization solution was transferred to a separatory funnel, hexane (150 parts by mass) was added to uniformly dilute the polymerization solution, and methanol (600 parts by mass) and water (30 parts by mass) were added and mixed. . After standing still for 30 minutes, the lower layer was collected and the solvent was replaced with propylene glycol monomethyl ether acetate. Thus, a propylene glycol monomethyl ether solution containing the polymer (B-1) was obtained. The polymer (B-1) had an Mw of 7,800 and an Mw/Mn of 1.8.

<Preparation of Radiation-Sensitive Resin Composition>
The [C] acid generator, [D] acid diffusion controller and [E] organic solvent 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" means the value when the mass of the [A] polymer used is 100 parts by mass, and "mol%" is used [ C] Means the value when the number of moles of the acid generator is 100 mol %.

[[C] acid generator]
[C] As an acid generator, compounds represented by the following formulas (C-1) to (C-10) (hereinafter also referred to as “acid generators (C-1) to (C-10)”) are used. board.

[[D] Acid diffusion control agent]
[D] As an acid diffusion control agent, compounds represented by the above compounds (D-1) to (D-14) and the following formulas (d-1) to (d-2) (hereinafter referred to as "compound (d-1 ) ~ (d-2)”) was used.

[[E] organic solvent]
[E] The following (E-1) and (E-2) were used as organic solvents.
(E-1): Propylene glycol monomethyl ether acetate (E-2): Propylene glycol monomethyl ether

[Example 1] Preparation of radiation-sensitive resin composition (R-1) [A] 100 parts by mass of (A-1) as a polymer, [B] 1 part by mass of (B-1) as a polymer, [C] 22 parts by mass of (C-1) as an acid generator, [D] 20 mol% of (D-1) as an acid diffusion controller based on (C-1), and [E] an organic solvent As (E-1) 5,500 parts by weight and (E-2) 1,500 parts by weight were mixed. A radiation-sensitive resin composition (R-1) was prepared by filtering the resulting mixture through a membrane filter with a pore size of 0.20 μm.

[Examples 2 to 30 and Comparative Examples 1 to 2] Preparation of radiation sensitive resin compositions (R-2) to (R-30) and (CR-1) to (CR-2) Types shown in Table 2 below Radiation-sensitive resin compositions (R-2) to (R-30) and (CR-1) to (CR-2) were prepared in the same manner as in Example 1 except that each component of and content was used. prepared.

<Formation of resist pattern>
A spin coater ("CLEAN TRACK ACT12" available from Tokyo Electron Co., Ltd.) was used to prepare the above preparation on the surface of a 12-inch silicon wafer on which an underlayer film having an average thickness of 20 nm ("AL412" available from Brewer Science) was formed. Each radiation sensitive resin composition was applied. After pre-baking (PB) at 130° C. for 60 seconds, it was cooled at 23° C. for 30 seconds to form a resist film with an average thickness of 30 nm. Next, this resist film was irradiated with EUV light using an EUV exposure machine ("NXE3300" by ASML, NA=0.33, illumination conditions: Conventional s=0.89, mask imecDEFECT32FFR02). After the irradiation, the resist film was post-exposure baked (PEB) at 130° C. for 60 seconds. Then, using a 2.38% by mass TMAH aqueous solution, development was performed at 23° C. for 30 seconds to form a positive contact hole pattern (25 nm diameter, 50 nm pitch).

<Evaluation>
Each resist pattern formed as described above was evaluated for sensitivity, CDU performance and resolution according to the following methods. A scanning electron microscope (“CG-4100” manufactured by Hitachi High-Tech Co., Ltd.) was used to measure the length of the resist pattern. The evaluation results are shown in Table 3 below.

[sensitivity]
In the formation of the resist pattern, the exposure amount for forming a contact hole pattern with a diameter of 25 nm was defined as the optimum exposure amount, and this optimum exposure amount was defined as Eop (mJ/cm ² ). Sensitivity was judged to be “good” when Eop was 60 mJ/cm ² or less, and “poor” when Eop was over 60 mJ/cm ² .

[CDU performance]
Using the above scanning electron microscope, the resist pattern was observed from above, the diameter of the contact hole pattern was measured at arbitrary points in total 800, and the 3 sigma value was obtained from the distribution of the measured values, which was expressed as CDU (unit: nm). The CDU performance indicates that the smaller the CDU value, the smaller the dispersion of the hole diameter in the long period and the better. The CDU performance was evaluated as "good" when the CDU was 4.5 nm or less and "bad" when the CDU was greater than 4.5 nm.

[Resolution]
In the formation of the resist pattern, the minimum diameter of the contact hole pattern resolved when the exposure dose was changed was measured, and this measured value was taken as the resolution (unit: nm). A smaller resolution value indicates better resolution. The resolution was evaluated as "good" when the resolution was 22 nm or less, and as "bad" when the resolution exceeded 22 nm.

Claims (8)

a polymer whose solubility in a developer changes under the action of an acid;
a radiation-sensitive acid generator;
A radiation-sensitive resin composition containing a compound represented by the following formula (1).

(In formula (1), Ar ¹ is a group obtained by removing (a + b + 2) hydrogen atoms from an aromatic hydrocarbon ring having 6 to 30 ring members. ^{R 1} is a monovalent an organic group or a halogen atom, L ¹ is a divalent linking group, R ² is a substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, a is 0 is an integer of up to 10. b is an integer of 1 to 10, provided that a+b is 10 or less, when a is 2 or more, a plurality of R ¹ are the same or different, and when b is 2 or more , a plurality of L ¹ are the same or different, a plurality of R ² are the same or different, and ^{X +} is a monovalent radiation-sensitive onium cation.) 2. The sensor according to claim 1, wherein R ² in the above formula (1) is a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms in which at least one hydrogen atom on the aromatic ring is replaced with an iodine atom. A radioactive resin composition. 3. According to claim 1 or claim 2, wherein L ¹ in the above formula (1) is a carbonyloxy group, an oxycarbonyl group, an ether group, a sulfide group, an alkanediyl group having 1 to 5 carbon atoms, or a combination thereof. radiation-sensitive resin composition. 4. The radiation-sensitive resin composition according to claim 1, 2 or 3, wherein the carboxylate group and the hydroxy group in the formula (1) are respectively bonded to adjacent carbon atoms constituting ^Ar1 . 5. The radiation-sensitive resin composition according to any one of claims 1 to 4, wherein the polymer has a structural unit containing an acid-labile group. 6. The radiation-sensitive resin composition according to claim 5, wherein the structural unit is represented by the following formula (2-1) or (2-2).

(In formulas (2-1) and (2-2), R ³ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. Z is an acid dissociable group.
In formula (2-2), L ² is a single bond, -COO-, -CONH- or -O-. Ar ² is a group obtained by removing (s+t+u+1) hydrogen atoms from an aromatic hydrocarbon ring having 6 to 20 ring members. s is an integer from 0-10 and t is an integer from 0-10. However, s+t is an integer of 1-10. When s is 2 or more, multiple Zs are the same or different. When s is 1 or more, R ⁴ is a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. When t is 2 or more, multiple R ⁴ are the same or different. When s is 0 and t is 1, ^R4 is an acid labile group. When s is 0 and t is 2 or more, at least one of the plurality of R ⁴ is an acid-labile group. R ⁵ is a monovalent organic group having 1 to 20 carbon atoms or a halogen atom. u is an integer from 0 to 10; When u is 2 or more, the plurality of ^R5 are the same or different. However, s+t+u is 10 or less. ) a step of directly or indirectly coating a substrate with the radiation-sensitive resin composition according to any one of claims 1 to 6;
A step of exposing the resist film formed by the coating step;
and a step of developing the exposed resist film. A compound represented by the following formula (1).

(In formula (1), Ar ¹ is a group obtained by removing (a + b + 2) hydrogen atoms from an aromatic hydrocarbon ring having 6 to 30 ring members. ^{R 1} is a monovalent an organic group or a halogen atom, L ¹ is a divalent linking group, R ² is a substituted or unsubstituted monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, a is 0 is an integer of up to 10. b is an integer of 1 to 10, provided that a+b is 10 or less, when a is 2 or more, a plurality of R ¹ are the same or different, and when b is 2 or more , a plurality of L ¹ are the same or different, a plurality of R ² are the same or different, and ^{X +} is a monovalent radiation-sensitive onium cation.)