TW202234154A - Radiation-sensitive resin composition, method of forming resist pattern, and polymer - Google Patents

Abstract

Provided are: a radiation-sensitive resin composition, a method of forming a resist pattern, and a polymer which enable forming a resist pattern with favorable sensitivity to exposure light and superiority in terms of CDU performance and resolution. The radiation-sensitive resin composition contains: a polymer having: a first structural unit represented by formula (1), and a second structural unit derived from a (meth)acrylic acid ester including an acid-labile group; and a radiation-sensitive acid generator.

Description

Radiation-sensitive resin composition, resist pattern forming method, and polymer

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

The radiation-sensitive resin composition used in the microfabrication by lithography is made of far-ultraviolet, extreme ultraviolet (Extreme Ultraviolet) light such as ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), etc. , EUV) (wavelength 13.5 nm) and other electromagnetic waves, charged particle beams such as electron beams and other radiations generate acid in the exposed part, and the exposed part and the non-exposed part are developed relative to each other by a chemical reaction using the acid as a catalyst. There is a difference in the dissolution rate of the liquid, and a resist pattern is formed on the substrate.

The radiation-sensitive resin composition is required not only to have good sensitivity to exposure light such as extreme ultraviolet rays and electron beams, but also to be excellent in critical dimension uniformity (CDU) performance and resolution.

In response to these requirements, the types and molecular structures of polymers, acid generators, and other components used in the radiation-sensitive resin composition have been studied, and their combinations have been studied in detail (refer to Japanese Patent Laid-Open No. 2010- 134279, Japanese Patent Laid-Open No. 2014-224984, and Japanese Patent Laid-Open No. 2016-047815). [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2010-134279 [Patent Document 2] Japanese Patent Laid-Open No. 2014-224984 [Patent Document 3] Japanese Patent Laid-Open No. 2016-047815

[The problem to be solved by the invention] With the further miniaturization of the resist pattern, the required level of the performance has been further increased, but the conventional radiation-sensitive resin composition could not satisfy these requirements.

The present invention is based on the above-mentioned circumstances, and an object of the present invention is to provide a radiation-sensitive resin composition and resist pattern formation capable of forming a resist pattern having good sensitivity to exposure light, CDU performance and resolution. Methods and polymers. [Means of Solving Problems]

（式（1）中，R ¹是氫原子、鹵素原子或碳數1～20的一價有機基。R ²及R ³分別獨立地為羥基、鹵素原子、硝基或碳數1～20的一價有機基。m是0～9的整數。n是0～9的整數。其中，m+n為9以下。於m為2以上的情況下，多個R ²彼此相同或不同。於n為2以上的情況下，多個R ³彼此相同或不同） The invention made in order to solve the above-mentioned problem is a radiation-sensitive resin composition containing a polymer (hereinafter, also referred to as "[A] polymer") having the following formula (1) and a second structural unit derived from a (meth)acrylate containing an acid dissociable group; and a radiation-sensitive acid generator (hereinafter, also referred to as "[B] acid generator"). [hua 1]

(In formula (1), R ¹ is a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms. R ² and R ³ are each independently a hydroxyl group, a halogen atom, a nitro group, or a carbon number 1 to 20 group. Monovalent organic group. m is an integer of 0 to 9. n is an integer of 0 to 9. However, m+n is 9 or less. When m is 2 or more, a plurality of R ² are the same or different from each other. In n In the case of 2 or more, a plurality of R ³ are the same or different from each other)

Another invention made in order to solve the above-mentioned problem is a method for forming a resist pattern, comprising: the step of directly or indirectly applying the radiation-sensitive resin composition on a substrate; A step of exposing the formed resist film; and a step of developing the exposed resist film.

Still another invention made in order to solve the above-mentioned problem is a polymer ([A] polymer) having the first structural unit represented by the above formula (1) and a polymer derived from an acid dissociable group containing The second structural unit of (meth)acrylate. [Effect of invention]

According to the radiation-sensitive resin composition and the 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 polymer of the present invention can be preferably used as a component of the radiation-sensitive resin composition. Therefore, these can be preferably used in the processing and the like of semiconductor elements which are expected to be further miniaturized in the future.

Hereinafter, the radiation-sensitive resin composition, the resist pattern forming method, and the polymer of the present invention will be described in detail.

<Radiation sensitive resin composition> The radiation-sensitive resin composition contains [A] a polymer and [B] an acid generator. The radiation-sensitive resin composition usually contains an organic solvent (hereinafter, also referred to as "[D] organic solvent"). The radiation-sensitive resin composition may contain an acid diffusion control agent (hereinafter, also referred to as "[C] acid diffusion control agent") as a preferable component. The radiation-sensitive resin composition may contain other arbitrary components within a range that does not impair the effects of the present invention.

By containing the [A] polymer and the [B] acid generator, the radiation-sensitive resin composition can form a resist pattern having good sensitivity to exposure light and excellent CDU performance and resolution. Although the reason why the radiation-sensitive resin composition exhibits the above-mentioned effect by including the above-mentioned structure is not necessarily clear, it can be estimated as follows, for example. That is, it is considered that the amount of the acid generated from the [B] acid generator or the like by exposure increases because the polymer [A] has a first structural unit represented by the following formula (1), which will be described later. Furthermore, it is considered that the acid dissociable group is dissociated from the second structural unit by the action of the acid generated from the [B] acid generator or the like, and the (methyl) derived from the high solubility in the developing solution is generated. In the case of the carboxyl group of acrylic acid, the amount of acid dissociable group dissociated from the second structural unit increases as the amount of acid generated from the [B] acid generator or the like increases, and the amount of carboxyl group derived from (meth)acrylic acid increases . As a result, it is considered that a resist pattern having good sensitivity to exposure light and excellent CDU performance and resolution can be formed.

The radiation-sensitive resin composition can be prepared, for example, by combining [A] a polymer, [B] an acid generator, and optionally [C] an acid diffusion control agent, [D] an organic solvent, and other arbitrary The components and the like are mixed in a predetermined ratio, and the obtained mixture is preferably filtered through a membrane filter having a pore size of 0.2 μm or less.

Hereinafter, each component contained in the radiation-sensitive resin composition will be described.

<[A] Polymer> [A] The polymer has a first structural unit (hereinafter, also referred to as "structural unit (I)") represented by the following formula (1) and derived from (meth)acrylate containing an acid dissociable group The second structural unit (hereinafter, also referred to as "structural unit (II)"). The radiation-sensitive resin composition may contain one kind or two or more kinds of [A] polymers.

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

The lower limit of the content ratio of the polymer [A] in the radiation-sensitive resin composition is preferably 50% by mass with respect to all components other than the organic solvent contained in the radiation-sensitive resin composition [D], More preferably, it is 70 mass %, and still more preferably, it is 80 mass %. As an upper limit of the said content ratio, 99 mass % is preferable, and 95 mass % is more preferable.

The lower limit of the polystyrene-equivalent weight average molecular weight (Mw) of the polymer [A] by gel permeation chromatography (GPC) is preferably 1,000, more preferably 3,000, and still more preferably 5,000, more preferably 6,000, particularly preferably 5,500. The upper limit of the Mw is preferably 50,000, more preferably 30,000, still more preferably 15,000, still more preferably 10,000, and particularly preferably 8,000. By setting the Mw of the [A] polymer to the above-mentioned range, the coatability of the radiation-sensitive resin composition can be improved.

The upper limit of the ratio (hereinafter, also referred to as "dispersity" or "Mw/Mn") of Mw obtained by GPC of the polymer to the number average molecular weight (Mn) in terms of polystyrene is preferably 2.5, more preferably 2.0, still more preferably 1.7. The lower limit of the ratio is usually 1.0, preferably 1.1, more preferably 1.2, still more preferably 1.3.

[Measuring method of Mw and Mn] The Mw and Mn of the [A] polymer in this specification are values measured using gel permeation chromatography (GPC) under the following conditions. GPC Columns: 2 "G2000HXL", 1 "G3000HXL" and 1 "G4000HXL" from Tosoh Co., Ltd. Column temperature: 40℃ Dissolution medium: 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

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

Hereinafter, each structural unit contained in the [A] polymer will be described.

[Structural unit (I)] The structural unit (I) is a structural unit represented by the following formula (1). Since the polymer [A] has the structural unit (I), a resist pattern having good sensitivity to exposure light and excellent CDU performance and resolution can be formed. [A] The polymer may have one or two or more structural units (I).

[hua 2]

In the above formula (1), R ¹ is a hydrogen atom, a halogen atom or a monovalent organic group having 1 to 20 carbon atoms. R ² and R ³ are each independently a hydroxyl group, a halogen atom, a nitro group, or a monovalent organic group having 1 to 20 carbon atoms. m is an integer of 0-9. n is an integer of 0-9. However, m+n is 9 or less. When m is 2 or more, a plurality of R ² are the same or different from each other. When n is 2 or more, a plurality of R ^3s are the same or different from each other.

As a halogen atom in R<^1> , R<^2> or R< ³ >, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom are mentioned.

In this specification, the "carbon number" refers to the number of carbon atoms constituting a group, and the "organic group" refers to a group containing at least one carbon atom.

Examples of the monovalent organic group having 1 to 20 carbon atoms represented by R ¹ , R ² or R ³ include a monovalent hydrocarbon group having 1 to 20 carbon atoms, and the hydrocarbon group includes a divalent heteroatom between carbon and carbon. The group (α) of the group, the hydrocarbon group, or the group (β) in which a part or all of the hydrogen atoms possessed by the group (α) are substituted with a monovalent heteroatom-containing group, the hydrocarbon group, the The above-mentioned group (α) or the above-mentioned group (β) combined with a divalent heteroatom-containing group (γ), etc.

The "hydrocarbon group" includes a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. The "hydrocarbon group" may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. The "chain hydrocarbon group" refers to a hydrocarbon group that does not contain a cyclic structure but consists only of a chain structure, and includes both a straight-chain hydrocarbon group and a branched-chain hydrocarbon group. The "alicyclic hydrocarbon group" refers to a hydrocarbon group including only an alicyclic structure as a ring structure but not an aromatic ring structure, and includes both a monocyclic alicyclic hydrocarbon group and a polycyclic alicyclic hydrocarbon group. Among them, it is not necessary to include only an alicyclic structure, and a chain structure may be included in a part thereof. The "aromatic hydrocarbon group" refers to a hydrocarbon group including an aromatic ring structure as a ring structure. Among them, it is not necessary to include only an aromatic ring structure, and a chain structure or an alicyclic structure may be included in a part thereof.

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 a monovalent aromatic group having 6 to 20 carbon atoms. Hydrocarbons etc.

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

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

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

As a heteroatom which comprises a monovalent or divalent heteroatom-containing group, an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom, a silicon atom, a halogen atom, etc. are mentioned, for example. As a halogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. are mentioned.

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

R ¹ is preferably a hydrogen atom from the viewpoint of providing copolymerizability of the monomer of the structural unit (I).

As m, 0 to 2 are preferable, 0 or 1 is more preferable, and 0 is still more preferable. As n, 0 to 2 are preferable, 0 or 1 is more preferable, and 0 is still more preferable. Among them, it is particularly preferable that both m and n are 0.

The lower limit of the content ratio of the structural unit (I) in the polymer [A] is preferably 0.5 mol %, more preferably 1 mol %, more preferably 0.5 mol % with respect to all the structural units constituting the [A] polymer. It is 2.5 mol%, more preferably 5 mol%. The upper limit of the content ratio is preferably 40 mol %, more preferably 30 mol %, more preferably 20 mol %, and further preferably 15 mol %. By setting the content ratio of the structural unit (I) within the above-mentioned range, the sensitivity to exposure light, CDU performance, and resolution of the radiation-sensitive resin composition can be further improved.

[Structural unit (II)] The structural unit (II) is a structural unit derived from a (meth)acrylate containing an acid dissociable group. In the present specification, the term "acid-dissociable group" refers to a group that replaces a hydrogen atom in a carboxyl group and dissociates by the action of an acid to provide a carboxyl group. "(meth)acrylate" is a concept including both acrylate and methacrylate. The acid dissociable group is dissociated by the action of the acid generated from the [B] acid generator or the like by the exposure, and the solubility of the [A] polymer in the developing solution between the exposed part and the non-exposed part is different. This can form a resist pattern. [A] The polymer may contain one or two or more structural units (II).

As the structural unit (II), for example, structural units represented by the following formulae (2-1) to (2-3) (hereinafter, also referred to as “structural unit (II-1) to structural unit (II- 3)") etc. In addition, for example, in the following formula (2-1), -C(R ^X )(R ^Y )(R ^Z ) bonded to an etheric oxygen atom derived from a carboxyl group corresponds to an acid dissociable group (a).

[hua 3]

In the above formula (2-1), formula (2-2) and formula (2-3), R ^T is each independently a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

In the formula (2-1), R ^X is each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^Y and R ^Z are each independently a substituted or unsubstituted monovalent hydrocarbon group with 1 to 20 carbon atoms, or the groups are bonded to each other and together with the bonded carbon atoms to form a ring member with a number of 3 to 3 ring members. Part of the saturated alicyclic structure of 20.

In the above formula (2-2), ^RA is a hydrogen atom. R ^B and R ^C are each 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 that forms an unsaturated alicyclic structure having 4 to 20 ring members together with the carbon atoms to which R ^A , R ^B and R ^C are each bonded.

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

In this specification, the "number of ring members" refers to the number of atoms constituting a ring structure, and in the case of a polycyclic ring, refers to the number of atoms constituting the polycyclic ring.

As the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^X , R ^Y , R ^Z , R ^B , R ^C , R ^U , R ^V or R ^W , for example, the same as R in the above formula (1) can be mentioned. ¹ . The same groups as those exemplified by the monovalent hydrocarbon group having 1 to 20 carbon atoms in the monovalent organic group having 1 to 20 carbon atoms in R ² or R ³ .

Examples of the substituent of the hydrocarbon group represented by R ^Y or R ^Z include a halogen atom such as a fluorine atom, a hydroxyl group, a carboxyl group, a cyano group, a nitro group, an alkoxy group, an alkoxycarbonyl group, and an alkoxy group. Carbonyloxy, acyloxy, acyloxy, etc. Among these, a halogen atom is preferable, and a fluorine atom is more preferable.

Examples of the saturated alicyclic structure having 3 to 20 ring members in which R ^Y and R ^Z are bonded together with the carbon atoms bonded to each other include a cyclopropane structure, a cyclobutane structure, and a cyclopentane structure. , monocyclic saturated alicyclic structures such as cyclohexane structure; polycyclic saturated alicyclic structures such as norbornane structure and adamantane structure, etc.

Examples of the divalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^D include those selected from among the monovalent organic groups having 1 to 20 carbon atoms in the formula (1) as R ¹ , R ² or R ³ , for example. A group obtained by removing one hydrogen atom from the groups exemplified as a monovalent hydrocarbon group having 1 to 20 carbon atoms.

Examples of the unsaturated alicyclic structure having 4 to 20 ring members composed of carbon atoms to which R ^D and R ^A , R ^B and R ^C are bonded together include, for example, a cyclobutene structure, a cyclopentene structure, a ring Monocyclic unsaturated alicyclic structures such as hexene structures; polycyclic unsaturated alicyclic structures such as norbornene structures, etc.

Examples of the alicyclic structure having 3 to 20 ring members in which R ^U and R ^V are bonded together with the carbon atoms bonded to each other include, for example, a cyclopropane structure, a cyclobutane structure, a cyclopentane structure, Monocyclic saturated alicyclic structures such as cyclohexane structure; polycyclic saturated alicyclic structures such as norbornane structure and adamantane structure; monocyclic structures such as cyclopropene structure, cyclobutene structure, cyclopentene structure and cyclohexene structure Cyclic unsaturated alicyclic structures; polycyclic unsaturated alicyclic structures such as norbornene structures, etc.

Examples of the aliphatic heterocyclic structure having 4 to 20 ring members in which R ^U and R ^W are bonded together with the carbon atom to which R ^U is bonded and the oxygen atom to which R ^W is bonded include, for example: oxygen heterocycle Butane structure, oxolane structure, oxane structure and other heterocyclic structures containing saturated oxygen; oxetene structure, oxolane structure, oxane structure, etc. Oxygen heterocyclic structure, etc.

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

As R ^X , a chain hydrocarbon group or an aromatic hydrocarbon group is preferable, an alkyl group or an aryl group is more preferable, and a methyl group, an ethyl group, an isopropyl group or a phenyl group is still more preferable.

R ^Y and R ^Z are preferably substituted or unsubstituted chain hydrocarbon groups or substituted or unsubstituted alicyclic hydrocarbon groups, more preferably unsubstituted chain hydrocarbon groups or substituted alicyclic hydrocarbon groups The hydrocarbon group is further preferably an unsubstituted alkyl group or a substituted cycloalkyl group, and further preferably a methyl group or a fluorine atom-substituted cyclohexyl group.

Moreover, R ^Y and R ^Z are also preferably a part of a saturated alicyclic structure having 3 to 20 ring members which are bonded to each other and constituted together with the carbon atoms bonded to each other. The saturated alicyclic structure is preferably a cyclopentane structure, a cyclohexane structure or an adamantane structure.

As R ^B , a hydrogen atom is preferred.

As R ^C , a hydrogen atom or a chain hydrocarbon group is preferable, a hydrogen atom or an alkyl group is more preferable, and a hydrogen atom or a methyl group is still more preferable.

The unsaturated alicyclic structure having 4 to 20 ring members formed by R ^D and the carbon atoms to which R ^A , R ^B and R ^C are bonded, respectively, is preferably a monocyclic unsaturated alicyclic structure, more preferably Cyclohexene structure.

As the structural unit (II), the structural unit (II-1) or the structural unit (II-2) is preferable.

The structural unit (II-1) is preferably, for example, a structural unit represented by the following formulae (2-1-1) to (2-1-8) (hereinafter, also referred to as "structural unit (II-1)" -1) ~ Structural unit (II-1-8)").

[hua 4]

In the above formulas (2-1-1) to (2-1-8), R ^T has the same meaning as the above formula (2-1).

The structural unit (II-2) is preferably a structural unit represented by the following formula (2-2-1) (hereinafter, also referred to as "structural unit (II-2-1)").

[hua 5]

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

The lower limit of the content ratio of the structural unit (II) in the polymer [A] is preferably 30 mol %, more preferably 40 mol %, more preferably 30 mol % with respect to all the structural units constituting the [A] polymer. is 50 mol%. The upper limit of the content ratio is preferably 90 mol %, more preferably 80 mol %, and still more preferably 70 mol %. By setting the content ratio of the structural unit (II) to the above-mentioned range, the sensitivity to exposure light, CDU performance, and resolution of the radiation-sensitive resin composition can be further improved.

[Structural unit (III)] The structural unit (III) is a structural unit containing a phenolic hydroxyl group. The "phenolic hydroxyl group" is not limited to the hydroxyl group directly bonded to the benzene ring, but refers to all the hydroxyl groups directly bonded to the aromatic ring. [A] The polymer may contain one or two or more of the structural units (III).

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

As the structural unit (III), for example, structural units represented by the following formulae (3-1) to (3-16) (hereinafter, also referred to as “structural unit (III-1) to structural unit (III- 16)") etc.

[hua 6]

In the above formulae (3-1) to (3-16), R ^P is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

As R ^P , a hydrogen atom or a methyl group is preferable, and a hydrogen atom is more preferable from the viewpoint of providing copolymerizability of the monomer of the structural unit (III).

As the structural unit (III), structural unit (III-1), structural unit (III-2), structural unit (III-3), structural unit (III-6), structural unit (III-15), Structural unit (III-16) or a combination of these. In the case of a combination, the CDU performance and resolution of the radiation-sensitive resin composition can be further improved. As a combination, preferably structural unit (III-1), structural unit (III-2), structural unit (III-3), structural unit (III-6), structural unit (III-15) or structural unit (III -16) combination.

When the [A] polymer has a structural unit (III), the lower limit of the content ratio of the structural unit (III) in the [A] polymer is preferable with respect to all the structural units constituting the [A] polymer. It is 5 mol %, more preferably 10 mol %, more preferably 20 mol %, particularly preferably 25 mol %. The upper limit of the content ratio is preferably 60 mol %, more preferably 50 mol %, further preferably 40 mol %, particularly preferably 35 mol %.

As a monomer which provides a structural unit (III), the monomer etc. which replaced the hydrogen atom of a phenolic hydroxyl group (-OH) with an acetyl group etc. can also be used, for example. In this case, the polymer [A] having the structural unit (III) can be synthesized by subjecting the obtained polymerization reaction product to a hydrolysis reaction in the presence of a base such as an amine after the monomer is polymerized, for example.

[Other Structural Units] Examples of other structural units include: a structural unit containing an alcoholic hydroxyl group (hereinafter, also referred to as "structural unit (IV)"); a lactone structure, a cyclic carbonate structure, a sultone structure, or those containing A combined structural unit (hereinafter, also referred to as "structural unit (V)") and the like. [A] The polymer may contain one kind or two or more kinds of other structural units.

(Structural Unit (IV)) The structural unit (IV) is a structural unit containing an alcoholic hydroxyl group. When the polymer [A] has a structural unit (IV), the sensitivity to exposure light and CDU performance of the radiation-sensitive resin composition can be further improved.

As a structural unit (IV), the structural unit etc. which are represented by the following formula are mentioned, for example.

[hua 7]

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

When the polymer [A] has a structural unit (IV), the lower limit of the content ratio of the structural unit (IV) is preferably 0.5 mol % with respect to all the structural units constituting the polymer [A], more preferably 0.5 mol %. Preferably, it is 1 mol %, and more preferably, it is 2.5 mol %. The upper limit of the content ratio is preferably 20 mol %, more preferably 15 mol %, and still more preferably 10 mol %.

(structural unit (V)) The structural unit (V) is a structural unit including a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination of these. When the polymer [A] has a structural unit (V), the CDU performance of the resist pattern formed from the radiation-sensitive resin composition may be further improved.

As a structural unit (V), the structural unit etc. which are represented by the following formula are mentioned, for example.

[hua 8]

[Chemical 9]

[Chemical 10]

[Chemical 11]

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

The structural unit (V) is preferably a structural unit containing a lactone structure or a cyclic carbonate structure.

When the polymer [A] has a structural unit (V), the lower limit of the content ratio of the structural unit (V) is preferably 0.5 mol % with respect to all the structural units constituting the polymer [A], more preferably 0.5 mol %. Preferably, it is 1 mol %, and more preferably, it is 2.5 mol %. The upper limit of the content ratio is preferably 20 mol %, more preferably 15 mol %, and still more preferably 10 mol %.

<[B] Acid generator> [B] An acid generator is a substance that generates an acid by exposure to light. As the exposure light, for example, the same ones as those exemplified as the exposure light in the exposure step of the resist pattern forming method described later can be mentioned. The acid dissociable group in the structural unit (II) contained in the polymer etc. is dissociated by the acid generated by exposure to generate a carboxyl group, and the resist film is exposed to the developer between the exposed portion and the non-exposed portion. A difference in solubility is produced in , whereby a resist pattern can be formed.

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

The form of containing the [B] acid generator in the radiation-sensitive resin composition may be, for example, a form of a compound that is not a polymer (hereinafter, also referred to as "[B] acid generator"), or may be a form of a compound that is not a polymer. The form in which a part of the polymer is introduced may be in both forms. The radiation-sensitive resin composition may contain one or two or more kinds of [B] acid generators.

As the [B] acid generator, for example, an onium salt compound, an N-sulfonyloxyimide compound, a sulfonylimide compound, a halogen-containing compound, a diazoketone compound, etc. are mentioned.

As an onium salt compound, a pernium salt, a tetrahydrothiophenium salt, an iodonium salt, a phosphonium salt, a diazonium salt, a pyridinium salt, etc. are mentioned, for example.

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

As an [B] acid generator which generates sulfonic acid by exposure, the compound represented by following formula (4) (henceforth "[B] compound") etc. are mentioned, for example. [Chemical 12]

In the formula (4), R ¹⁴ is a monovalent organic group having 1 to 30 carbon atoms. R ¹⁵ is a hydrogen atom, a fluorine atom, or a monovalent organic group having 1 to 10 carbon atoms. Y ⁺ is a monovalent radioactive onium cation.

Examples of the monovalent organic group having 1 to 30 carbon atoms represented by R ¹⁴ include monovalent organic groups having 1 to 20 carbon atoms represented by R ¹ , R ² or R ³ in the above formula (1). On the other hand, the exemplified monovalent organic groups are the same groups and the like.

Examples of the monovalent organic group having 1 to 10 carbon atoms represented by R ¹⁵ include monovalent organic groups having 1 to 20 carbon atoms represented by R ¹ , R ² or R ³ in the above formula (1). On the other hand, the exemplified monovalent organic groups are the same groups and the like.

The organic group represented by R ¹⁴ is preferably a monovalent group containing a ring structure having 5 or more ring members. Examples of the ring structure having 5 or more ring members include an alicyclic structure having 5 or more ring members, an aliphatic heterocyclic structure having 5 or more ring members, an aromatic carbocyclic structure having 5 or more ring members, 5 or more aromatic heterocyclic structures or combinations thereof, etc.

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

Examples of the aliphatic heterocyclic structure having 5 or more ring members include lactone structures such as a caprolactone structure and a norbornane lactone structure; a caprolactone structure, a norbornane sultone structure, and the like. Sultone structure; oxygen-containing heterocyclic structures such as oxane structure and oxanorbornane structure; nitrogen-containing heterocyclic structures such as azacyclohexane structure and diazabicyclooctane structure; Heterocyclic structures containing sulfur atoms such as thiacyclohexane structures, thianorbornane structures, etc.

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

Examples of the aromatic heterocyclic structure having 5 or more ring members include oxygen atom-containing heterocyclic structures such as a furan structure, a pyran structure, a benzofuran structure, and a benzopyran structure; a pyridine structure, a pyrimidine structure, an indone structure Nitrogen-containing heterocyclic structures such as inole structures, etc.

The lower limit of the number of ring members of the ring structure is preferably 6, more preferably 8, still more preferably 9, particularly preferably 10. The upper limit of the number of ring members is preferably 15, more preferably 14, still more preferably 13, particularly preferably 12.

As R ¹⁵ , a fluorine atom is preferred.

Examples of the monovalent radioactive onium cation represented by Y ⁺ include monovalent cations represented by the following formulae (ra) to (rc) (hereinafter, also referred to as “cation (ra) to cation (rc)) ")Wait.

[Chemical 13]

In the said formula (ra), b1 is an integer of 0-4. When b1 is 1, R ^B1 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen atom. When b1 is 2 or more, a plurality of R ^B1 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 A part of a ring structure having 4 to 20 ring members formed by the bonded carbon chains. b2 is an integer of 0-4. When b2 is 1, R ^B2 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen atom. When b2 is 2 or more, a plurality of R ^B2 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 A part of a ring structure having 4 to 20 ring members formed by the bonded carbon chains. R ^B3 and R ^B4 are each independently a hydrogen atom, a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen atom, or represent a single bond formed by combining these. b3 is an integer of 0-11. When b3 is 1, R ^B5 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, or a halogen atom. When b3 is 2 or more, a plurality of R ^B5 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 A part of a ring structure having 4 to 20 ring members formed by the bonded carbon chains. n _b1 is an integer of 0-3.

In the above formula (rb), 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, a plurality of R ^B6 are the same or different from each other, and are a monovalent organic group with 1 to 20 carbon atoms, a hydroxyl group, a nitro group or a halogen atom, or these groups are combined with each other and A part of a ring structure with 4 to 20 ring members formed by the bonded carbon chains. b5 is an integer of 0-10. 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, a plurality of R ^B7 are the same or different from each other, and are monovalent organic groups with 1 to 20 carbon atoms, hydroxyl groups, nitro groups or halogen atoms, or these groups are combined with each other and A part of a ring structure with 3 to 20 ring members composed of bonded carbon atoms or carbon chains. n _b3 is an integer of 0-3. R ^B8 is a single bond or a divalent organic group having 1 to 20 carbon atoms. n _b2 is an integer of 0-2.

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

As the monovalent organic group having 1 to 20 carbon atoms represented by R ^B1 , R ^B2 , R ^B3 , R ^B4 , R ^B5 , R ^B6 , R ^B7 , R ^B9 and R ^B10 , for example, those represented by the formula ( The monovalent organic group having 1 to 20 carbon atoms represented by R ¹ , R ² or R ³ in 1) is the same as the group exemplified.

The divalent organic group represented by R ^B8 is, for example, removed from the groups exemplified as the monovalent organic group having 1 to 20 carbon atoms represented by R ¹ , R ² or R ³ in the above formula (1). A base made of a hydrogen atom, etc.

As R ^B3 and R ^B4 , hydrogen atoms or single bonds bonded to each other are preferable.

As b1 and b2, 0 to 2 are preferable, 0 or 1 is more preferable, and 0 is still more preferable. As b3, 0-4 are preferable, 0-2 are more preferable, and 0 or 1 are still more preferable. As n _b1 , 0 or 1 is preferable.

When b3 is 1 or more, R ^B5 is preferably a cyclohexyl group or a cyclohexylsulfonyl group.

The monovalent radioactive onium cation represented by Y ⁺ is preferably a cation (ra).

Examples of the cation (r-a) include cations represented by the following formulae (r-a-1) to (r-a-7) (hereinafter, also referred to as "cation (r-a-1) to cation (r-a-7)") Wait.

[Chemical 14]

Examples of the compound [B] include compounds represented by the following formulae (4-1) to (4-8) (hereinafter, also referred to as "compound (B1) to compound (B8)") and the like.

[Chemical 15]

In the above formulas (4-1) to (4-8), Y ⁺ has the same meaning as the above formula (4).

The lower limit of the content of the [B] acid generator in the radiation-sensitive resin composition is preferably 5 parts by mass, more preferably 10 parts by mass, and still more preferably 15 parts by mass relative to 100 parts by mass of the [A] polymer parts by mass. The upper limit of the content is preferably 60 parts by mass, more preferably 55 parts by mass, still more preferably 50 parts by mass. By setting the content of the acid generator [B] to the above-mentioned range, the sensitivity to exposure light, CDU performance, and resolution of the radiation-sensitive resin composition can be further improved.

＜[C]Acid Diffusion Control Agent＞ The [C] acid diffusion control agent has the effect of controlling the diffusion phenomenon in the resist film of the acid generated from the [B] acid generator or the like by exposure, and controlling the unsatisfactory chemical reaction in the non-exposed area. By containing [C] an acid diffusion control agent, the radiation-sensitive resin composition can further improve the sensitivity to exposure light, CDU performance, and resolution of the radiation-sensitive resin composition. The radiation-sensitive resin composition may contain one or two or more kinds of [C] acid diffusion control agents.

[C] As an acid diffusion control agent, a nitrogen atom-containing compound, a photodegradable base which is exposed to light and generates a weak acid, etc. are mentioned, for example.

Examples of the nitrogen atom-containing compound include amine compounds such as triamylamine and trioctylamine; carbamide group-containing compounds such as carboxamide and N,N-dimethylacetamide; urea, 1, Urea compounds such as 1-dimethylurea; pyridine, N-(undecylcarbonyloxyethyl)morpholine, 1-(tertiary butoxycarbonyl)-4-hydroxypiperidine, N-tertiary pentane Nitrogen-containing heterocyclic compounds such as oxycarbonyl-4-hydroxypiperidine, etc. Among these, an amine compound or a nitrogen-containing heterocyclic compound is preferable, and trioctylamine or 1-(3-butoxycarbonyl)-4-hydroxypiperidine is more preferable.

Examples of the photodegradable base include compounds containing an onium cation decomposed by exposure and an anion of a weak acid. The photodegradable alkali generates an acid in the exposed part to increase the solubility or insolubility of the polymer [A] with respect to the developing solution, and as a result, the roughness of the exposed part surface after development is suppressed. On the other hand, in the non-exposed part, the anion exhibits a high acid capturing function, and it functions as a quencher, and captures the acid diffused from the exposed part. That is, since it functions as a quencher only in the non-exposed part, the contrast of the deprotection reaction is improved, and as a result, the resolution can be improved.

Examples of the onium cation decomposed by the exposure include the same ones exemplified as the monovalent radiosensitive onium cation in the [B] acid generator. Among them, a triphenyl perionium cation or a phenyl dibenzothiophenium cation is preferable.

As an anion of the said weak acid, the anion etc. which are represented by the following formula are mentioned, for example.

[Chemical 16]

As the photodegradable base, a compound obtained by appropriately combining the onium cation decomposed by the exposure and the anion of the weak acid can be used.

When the radiation-sensitive resin composition contains the [C] acid diffusion control agent, as the lower limit of the content ratio of the [C] acid diffusion control agent in the radiation-sensitive resin composition, with respect to the [B] acid generation The dosage is 100 mol%, preferably 1 mol%, more preferably 5 mol%, and further preferably 10 mol%. The upper limit of the content is preferably 100 mol %, more preferably 60 mol %, and still more preferably 50 mol %. By setting the content ratio of the acid diffusion control agent [C] to the above-mentioned range, the sensitivity to exposure light, CDU performance, and resolution of the radiation-sensitive resin composition can be further improved.

＜[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 can dissolve or disperse at least the [A] polymer and the [B] acid generator, and optionally the [C] acid diffusion control agent and other optional components. limited.

[D] As an organic solvent, an alcohol-based solvent, an ether-based solvent, a ketone-based solvent, an amide-based solvent, an ester-based solvent, a hydrocarbon-based solvent, etc. are mentioned, for example. The radiation-sensitive resin composition may contain one or more [D] organic solvents.

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

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

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

Examples of the amide-based solvent include cyclic amide-based solvents such as N,N'-dimethylimidazolidinone and N-methylpyrrolidone; Methylformamide, N,N-diethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpropionamide, etc. amide-based solvent, etc.

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

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

The organic solvent [D] is preferably an alcohol-based solvent and/or an ester-based solvent, more preferably a polyhydric alcohol partial ether-based solvent and/or a polyhydric alcohol partial ether carboxylate-based solvent having 3 to 19 carbon atoms, and even more preferably It is propylene glycol-1-monomethyl ether and/or propylene glycol monomethyl ether acetate.

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

<Other optional ingredients> As other arbitrary components, surfactant etc. are mentioned, for example. The radiation-sensitive resin composition may contain one or two or more other optional components.

<Method for forming a resist pattern> The resist pattern forming method includes: a step of directly or indirectly applying a radiation-sensitive resin composition to a substrate (hereinafter, also referred to as a "coating step"); A step of exposing the resist film (hereinafter, also referred to as an “exposure 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 as the radiation-sensitive resin composition in the coating step, it is possible to form a good sensitivity to exposure light and excellent CDU performance and resolution. resist pattern.

Hereinafter, each step included in the resist pattern forming method will be described.

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

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

As the substrate, for example, conventionally known ones, such as a silicon wafer, a silicon dioxide, and an aluminum-coated wafer, can be mentioned. Moreover, as a case where this radiation sensitive resin composition is indirectly apply|coated to a board|substrate, the case where this radiation sensitive resin composition is apply|coated to the antireflection film formed on a board|substrate, etc. are mentioned, for example. Examples of such an antireflection film include organic or inorganic antireflection films disclosed in Japanese Patent Laid-Open No. 6-12452, Japanese Patent Laid-Open No. 59-93448, and the like.

As a coating method, spin coating (spin coating), casting coating, roll coating, etc. are mentioned, for example. After coating, in order to volatilize the solvent in the coating film, pre-bake (PB) (hereinafter, also referred to as "PB") may be performed as necessary. As a lower limit of the temperature of PB, 60 degreeC is preferable, and 80 degreeC is more preferable. The upper limit of the temperature is preferably 150°C, more preferably 140°C. As a lower limit of the time of PB, 5 seconds are preferable, and 10 seconds are more preferable. 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 step] In this step, the resist film formed by the coating step is exposed to light. This exposure is performed by irradiating exposure light through a photomask (in some cases, through a liquid immersion medium such as water). Examples of exposure light include electromagnetic waves such as visible rays, ultraviolet rays, extreme ultraviolet rays, extreme ultraviolet rays (EUV), X rays, and γ rays, and charged particle beams such as electron beams and α rays, depending on the line width and the like of the target pattern. Among these, far-ultraviolet rays, EUV or electron beams are preferred, and ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), EUV (wavelength 13.5 nm) or electron beams are more preferred, Further preferred is KrF excimer laser light, EUV or electron beam, and particularly preferred is EUV or electron beam.

It is preferable to perform a Post Exposure Bake (PEB) (hereinafter, also referred to as "PEB") after the exposure, and the exposed portion of the resist film is exposed to [B]. ] An acid generated by an acid generator or the like promotes the dissociation of the acid dissociable group possessed by the [A] polymer or the like. With this PEB, the difference in solubility in the developer can be increased between the exposed portion and the non-exposed portion. As a lower limit of the temperature of PEB, 50 degreeC is preferable, 80 degreeC is more preferable, and 100 degreeC is still more preferable. The upper limit of the temperature is preferably 180°C, more preferably 130°C. The lower limit of the time for PEB is preferably 5 seconds, more preferably 10 seconds, and still more preferably 30 seconds. The upper limit of the time is preferably 600 seconds, more preferably 300 seconds, and still more preferably 100 seconds.

[Development step] In this step, the exposed resist film is developed. Thereby, a predetermined resist pattern can be formed. Generally, it is washed with a rinse solution such as water or alcohol and dried after development. The developing method in the developing step may be alkali development or organic solvent development.

In the case of alkali development, examples of the developer for development include dissolving sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia water, ethylamine, n-propylamine, Diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (hereinafter, also referred to as "TMAH (Tetramethyl ammonium hydroxide)" Ammonium Hydroxide)"), pyrrole, piperidine, choline, 1,8-diazabicyclo-[5.4.0]-7-undecene, 1,5-diazabicyclo-[4.3.0]- An alkaline aqueous solution of at least one basic compound such as 5-nonene, etc. Among these, TMAH aqueous solution is preferable, and 2.38 mass % TMAH aqueous solution is more preferable.

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

Examples of the developing method include: a method of immersing a substrate in a tank filled with a developing solution for a fixed period of time (dipping method); a method of developing by depositing a developing solution on the surface of the substrate by utilizing surface tension and standing still for a fixed period of time (overlay method) liquid (puddle) method); the method of spraying the developer on the surface of the substrate (spray method); the method of continuously spraying the developer on the substrate rotating at a fixed speed while scanning the developer ejection nozzle at a fixed speed (dynamic distribution method) )Wait.

As a pattern formed by this resist pattern formation method, a line-and-space pattern, a hole pattern, etc. are mentioned, for example.

＜Polymer＞ This compound was described as the [A] polymer in the radiation-sensitive resin composition. This polymer can be preferably used as a component of a radiation-sensitive resin composition. [Example]

Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. The measurement method of each physical property value is shown below.

[Weight-average molecular weight (Mw), number-average molecular weight (Mn), and degree of dispersion (Mw/Mn)] [A] The Mw and Mn of the polymer were measured under the conditions described in the item of the above-mentioned [Method for Measuring Mw and Mn]. The degree of dispersion (Mw/Mn) of the polymer was calculated from the measurement results of Mw and Mn.

<[A] Synthesis of polymer> The monomers represented by the following formulas (M-1) to (M-20) (hereinafter, also referred to as "monomers (M-1) to monomers) were used in the synthesis of the polymer [A]. (M-20)”). In the following synthesis examples, unless otherwise specified, the parts by mass refer to the value when the total mass of the monomers used is 100 parts by mass, and the mole % refers to the total of the monomers used. The number of moles is set to 100 mole%.

[Chemical 17]

[Synthesis Example 1] Synthesis of Polymer (A-1) Monomer (M-5), Monomer (M-6) and Monomer (M-1) were dissolved in propylene glycol-1-monomethyl ether (200 parts by mass). Next, 6 mol % of azobisisobutyronitrile (AIBN) was added as a starting agent to prepare a monomer solution. On the other hand, propylene glycol-1-monomethyl ether (100 parts by mass) was placed in an empty reaction vessel, and the mixture was heated to 85°C while stirring. Next, the prepared monomer solution was added dropwise over 3 hours, and then further heated at 85°C for 3 hours, and the polymerization reaction was carried out for a total of 6 hours. After the polymerization reaction was completed, the polymerization solution was cooled to room temperature.

The cooled polymerization solution was put into hexane (500 parts by mass with respect to the polymerization solution), and the precipitated white powder was separated by filtration. After the white powder separated by filtration was washed twice with 100 parts by mass of hexane with respect to the polymerization solution, it was separated by filtration and dissolved in propylene glycol-1-monomethyl ether (300 parts by mass). Next, methanol (500 parts by mass), triethylamine (50 parts by mass), and ultrapure water (10 parts by mass) were added, and a hydrolysis reaction was performed at 70° C. for 6 hours while stirring. After the hydrolysis reaction was completed, the residual solvent was distilled off, and the obtained solid was dissolved in acetone (100 parts by mass). The resin was added dropwise to 500 parts by mass of water to solidify the resin, and the obtained solid was separated by filtration. It dried at 50 degreeC for 12 hours, and obtained the white powdery polymer (A-1). The Mw of the polymer (A-1) was 7,100, and the Mw/Mn was 1.52.

[Synthesis Example 2 to Synthesis Example 21] Synthesis of Polymer (A-2) to Polymer (A-20) and Polymer (a-1) A polymer (A-2) to a polymer (A-20) and a polymer (a-1) were synthesized in the same manner as in Synthesis Example 1, except that the monomers of the types and usage ratios shown in the following Table 1 were used.

The types and usage ratios of monomers that provide each structural unit of the polymers obtained in Synthesis Example 1 to Synthesis Example 21, as well as Mw and Mw/Mn are shown in Table 1 below. In addition, in Table 1, "-" shows that the corresponding monomer was not used.

[Table 1] [A] Polymer Monomers that provide structural units (I) Monomers that provide structural unit (II) Monomers that provide structural unit (III) Monomers that provide other building blocks Mw Mw/Mn type Use ratio (mol%) type Use ratio (mol%) type Use ratio (mol%) type Use ratio (mol%) Synthesis Example 1 A-1 M-5 5 M-6 60 M-1 35 - - 7100 1.5 Synthesis Example 2 A-2 M-5 10 M-6 60 M-1 30 - - 7200 1.6 Synthesis Example 3 A-3 M-5 15 M-6 60 M-1 25 - - 7500 1.6 Synthesis Example 4 A-4 M-5 5 M-6 60 M-1/M-2 30/5 - - 7000 1.5 Synthesis Example 5 A-5 M-5 5 M-6 60 M-1/M-3 30/5 - - 6500 1.5 Synthesis Example 6 A-6 M-5 5 M-6 60 M-1/M-4 30/5 - - 6900 1.6 Synthesis Example 7 A-7 M-5 5 M-7 60 M-1 35 - - 6800 1.5 Synthesis Example 8 A-8 M-5 5 M-8 60 M-1 35 - - 6700 1.5 Synthesis Example 9 A-9 M-5 5 M-9 60 M-1 35 - - 6700 1.6 Synthesis Example 10 A-10 M-5 5 M-10 60 M-1 35 - - 6600 1.6 Synthesis Example 11 A-11 M-5 5 M-11 60 M-1 35 - - 7000 1.6 Synthesis Example 12 A-12 M-5 5 M-12 60 M-1 35 - - 7500 1.6 Synthesis Example 13 A-13 M-5 5 M-13 60 M-1 35 - - 6300 1.5 Synthesis Example 14 A-14 M-5 5 M-14 60 M-1 35 - - 6000 1.6 Synthesis Example 15 A-15 M-5 5 M-6 60 M-1 30 M-15 5 6500 1.6 Synthesis Example 16 A-16 M-5 5 M-6 60 M-1 30 M-16 5 6400 1.6 Synthesis Example 17 A-17 M-5 5 M-6 60 M-1 30 M-17 5 7100 1.5 Synthesis Example 18 A-18 M-5 5 M-6 60 M-1 30 M-18 5 7200 1.6 Synthesis Example 19 A-19 M-5 5 M-6 60 M-1/M-19 30/5 - - 7100 1.5 Synthesis Example 20 A-20 M-5 5 M-6 60 M-1/M-20 30/5 - - 7400 1.6 Synthesis Example 21 a-1 - - M-6 60 M-1 40 - - 7600 1.6

<Preparation of radiation-sensitive resin composition> The [B] acid generator, [C] acid diffusion control agent, and [D] 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 refer to the value when the mass of the used [A] polymer is 100 parts by mass, and mol % refers to the amount of the [A] polymer used. B] The value when the molar number of the acid generator is set to 100 mol %.

[[B] Acid generator] As the [B] acid generator, compounds represented by the following formulae (B-1) to (B-8) (hereinafter, also referred to as "acid generator (B-1) to acid generator (B- 8)").

[Chemical 18]

[[C] Acid Diffusion Control Agent] As the [C] acid diffusion control agent, compounds represented by the following formulae (C-1) to (C-8) (hereinafter, also referred to as "acid diffusion control agent (C-1) to acid diffusion control agent) were used. (C-8)").

[Chemical 19]

[[D]Organic solvent] As the [D] organic solvent, the following (D-1) and (D-2) were used. (D-1): Propylene glycol monomethyl ether acetate (D-2): Propylene glycol-1-monomethyl ether

[Example 1] Preparation of radiation-sensitive resin composition (R-1) 100 parts by mass of (A-1) as the [A] polymer, 20 parts by mass of (B-1) as the [B] acid generator, and 45 mol % with respect to (B-1) were used as [ C] (C-1) of an acid diffusion control agent, and [D] 4,800 mass parts of (D-1) and (D-2) 2,000 mass parts as an organic solvent were mixed. The obtained mixed solution was filtered through a membrane filter with a pore size of 0.20 μm, thereby preparing a radiation-sensitive resin composition (R-1).

[Examples 2 to 28 and Comparative Example 1] Preparation of radiation-sensitive resin composition (R-2) to radiation-sensitive resin composition (R-36) and radiation-sensitive resin composition (CR-1) A radiation-sensitive resin composition (R-2) to a radiation-sensitive resin composition (R-36) and a radiation-sensitive resin composition (R-36) and a radiation-sensitive resin composition were prepared in the same manner as in Example 1, except that each component of the type and content shown in the following Table 2 was used. Resin composition (CR-1).

[Table 2] Radiation sensitive resin composition [A] Polymer [B] Acid generator [C] Acid diffusion control agent [D] Organic solvent type Content (mass parts) type Content (mass parts) type Content ratio (mol%) type Content (mass parts) Example 1 R-1 A-1 100 B-1 20 C-1 45 D-1/D-2 4800/2000 Example 2 R-2 A-2 100 B-1 20 C-1 45 D-1/D-2 4800/2000 Example 3 R-3 A-3 100 B-1 20 C-1 45 D-1/D-2 4800/2000 Example 4 R-4 A-4 100 B-1 20 C-1 45 D-1/D-2 4800/2000 Example 5 R-5 A-5 100 B-1 20 C-1 45 D-1/D-2 4800/2000 Example 6 R-6 A-6 100 B-1 20 C-1 45 D-1/D-2 4800/2000 Example 7 R-7 A-7 100 B-1 20 C-1 45 D-1/D-2 4800/2000 Example 8 R-8 A-8 100 B-1 20 C-1 45 D-1/D-2 4800/2000 Example 9 R-9 A-9 100 B-1 20 C-1 45 D-1/D-2 4800/2000 Example 10 R-10 A-10 100 B-1 20 C-1 45 D-1/D-2 4800/2000 Example 11 R-11 A-11 100 B-1 20 C-1 45 D-1/D-2 4800/2000 Example 12 R-12 A-12 100 B-1 20 C-1 45 D-1/D-2 4800/2000 Example 13 R-13 A-13 100 B-1 20 C-1 45 D-1/D-2 4800/2000 Example 14 R-14 A-14 100 B-1 20 C-1 45 D-1/D-2 4800/2000 Example 15 R-15 A-15 100 B-1 20 C-1 45 D-1/D-2 4800/2000 Example 16 R-16 A-16 100 B-1 20 C-1 45 D-1/D-2 4800/2000 Example 17 R-17 A-17 100 B-1 20 C-1 45 D-1/D-2 4800/2000 Example 18 R-18 A-18 100 B-1 20 C-1 45 D-1/D-2 4800/2000 Example 19 R-19 A-19 100 B-1 20 C-1 45 D-1/D-2 4800/2000 Example 20 R-20 A-20 100 B-1 20 C-1 45 D-1/D-2 4800/2000 Example 21 R-21 A-1 100 B-1 30 C-1 45 D-1/D-2 4800/2000 Example 22 R-22 A-1 100 B-1 40 C-1 45 D-1/D-2 4800/2000 Example 23 R-23 A-1 100 B-2 20 C-1 45 D-1/D-2 4800/2000 Example 24 R-24 A-1 100 B-3 20 C-1 45 D-1/D-2 4800/2000 Example 25 R-25 A-1 100 B-4 20 C-1 45 D-1/D-2 4800/2000 Example 26 R-26 A-1 100 B-5 20 C-1 45 D-1/D-2 4800/2000 Example 27 R-27 A-1 100 B-6 20 C-1 45 D-1/D-2 4800/2000 Example 28 R-28 A-1 100 B-7 20 C-1 45 D-1/D-2 4800/2000 Example 29 R-29 A-1 100 B-8 20 C-1 45 D-1/D-2 4800/2000 Example 30 R-30 A-1 100 B-1 20 C-2 45 D-1/D-2 4800/2000 Example 31 R-31 A-1 100 B-1 20 C-3 45 D-1/D-2 4800/2000 Example 32 R-32 A-1 100 B-1 20 C-4 45 D-1/D-2 4800/2000 Example 33 R-33 A-1 100 B-1 20 C-5 45 D-1/D-2 4800/2000 Example 34 R-34 A-1 100 B-1 20 C-6 45 D-1/D-2 4800/2000 Example 35 R-35 A-1 100 B-1 20 C-7 45 D-1/D-2 4800/2000 Example 36 R-36 A-1 100 B-1 20 C-8 45 D-1/D-2 4800/2000 Comparative Example 1 CR-1 a-1 100 B-1 20 C-1 45 D-1/D-2 4800/2000

<Formation of resist pattern> Using a spin coater (“CLEAN TRACK ACT12” from Tokyo Electron Co., Ltd.), each of the radiation-sensitive resin compositions prepared as described above was applied to an underlayer film (Brewer) formed with an average thickness of 20 nm. Technology (Brewer Science) "AL412") 12-inch silicon wafer surface. After prebaking (PB) for 60 seconds at 130° C., it 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 irradiated with EUV using an EUV exposure machine (“NXE3300” from ASML, numerical aperture (NA)=0.33, illumination condition: conventional (Conventional) s=0.89, mask: imecDEFECT32FFR02) Light. After irradiation, the resist film was subjected to a post-exposure bake (PEB) at 130° C. for 60 seconds. Next, using a 2.38 mass % TMAH aqueous solution, development was performed at 23° C. for 30 seconds to form a positive-type contact hole pattern (diameter 25 nm, pitch 50 nm).

＜Evaluation＞ For each resist pattern formed as described above, sensitivity, CDU performance, and resolution were evaluated by the following methods. The length of the resist pattern was measured using a scanning electron microscope (“CG-4100” of Hitachi High-Tech Co., Ltd.). 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 the optimum exposure amount was defined as Eop (mJ/cm ² ). Regarding the sensitivity, the case where Eop was 50 mJ/cm ² or less was judged as "good", and the case where Eop exceeded 50 mJ/cm ² was judged as "defect".

[CDU performance] The resist pattern was observed from the top using the scanning electron microscope, the diameters of a total of 800 contact hole patterns were measured at arbitrary locations, and the 3-sigma value was obtained from the distribution of the measured values, which was defined as CDU (unit: nm) . Regarding the CDU performance, the smaller the value of the CDU, the smaller the deviation of the aperture in the long period, which means the better the CDU performance. Regarding CDU performance, the case where the CDU was 4.3 nm or less was evaluated as "good", and the case where the CDU exceeded 4.3 nm was evaluated as "poor".

[analytical] In the formation of the resist pattern, the diameter of the smallest contact hole pattern for which the analysis was obtained was measured while changing the exposure amount, and the measured value was used as the resolution (unit: nm). Regarding the resolution, the smaller the value of the resolution, the better the resolution. Regarding the resolution, the case where the resolution was 24.5 nm or less was evaluated as "good", and the case where the resolution exceeded 24.5 nm was evaluated as "poor".

[table 3] Radiation sensitive resin composition Eop (mJ/cm ² ) CDU (nm) Resolution (nm) Example 1 R-1 48 4.2 22.5 Example 2 R-2 49 4.0 20.5 Example 3 R-3 50 3.8 18.5 Example 4 R-4 49 4.1 21.5 Example 5 R-5 49 4.1 20.5 Example 6 R-6 46 4.1 20.5 Example 7 R-7 48 4.1 21.5 Example 8 R-8 49 4.0 18.5 Example 9 R-9 47 4.3 24.5 Example 10 R-10 48 4.1 19.5 Example 11 R-11 49 4.1 23.5 Example 12 R-12 48 4.0 20.5 Example 13 R-13 50 4.4 24.5 Example 14 R-14 48 3.9 19.5 Example 15 R-15 47 4.1 23.5 Example 16 R-16 47 4.1 20.5 Example 17 R-17 48 4.2 23.5 Example 18 R-18 48 4.1 23.5 Example 19 R-19 46 4.0 23.0 Example 20 R-20 48 4.0 22.0 Example 21 R-21 49 4.2 19.5 Example 22 R-22 50 4.3 20.5 Example 23 R-23 47 4.1 21.5 Example 24 R-24 46 4.0 19.5 Example 25 R-25 49 4.3 20.5 Example 26 R-26 48 4.3 24.5 Example 27 R-27 47 4.3 23.5 Example 28 R-28 46 3.9 20.0 Example 29 R-29 44 3.8 19.0 Example 30 R-30 47 4.1 18.5 Example 31 R-31 46 4.3 21.5 Example 32 R-32 45 4.3 20.5 Example 33 R-33 44 4.1 20.0 Example 34 R-34 43 4.0 18.5 Example 35 R-35 41 3.9 18.0 Example 36 R-36 42 3.9 18.0 Comparative Example 1 CR-1 53 4.6 25.5

As is clear from the results in Table 3, compared with the radiation-sensitive resin compositions of Comparative Examples, the radiation-sensitive resin compositions of the Examples were all favorable in sensitivity, CDU performance, and resolution. [Industrial Availability]

According to the radiation-sensitive resin composition and the 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 polymer of the present invention can be preferably used as a component of the radiation-sensitive resin composition. Therefore, these can be preferably used in the processing and the like of semiconductor elements which are expected to be further miniaturized in the future.

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Claims (5)

A radiation-sensitive resin composition comprising: a polymer having a first structural unit represented by the following formula (1) and a second structural unit derived from a (meth)acrylate containing an acid dissociable group; and a sensor radioactive acid generators;

(In formula (1), R ¹ is a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms; R ² and R ³ are independently a hydroxyl group, a halogen atom, a nitro group, or a monovalent organic group having 1 to 20 carbon atoms. monovalent organic group; m is an integer of 0 to 9; n is an integer of 0 to 9; wherein, m+n is 9 or less; when m is 2 or more, a plurality of R ² are the same or different from each other; In the case of 2 or more, a plurality of R ³ are the same or different from each other). The radiation-sensitive resin composition according to claim 1, wherein R ¹ in the formula (1) is a hydrogen atom. The radiation-sensitive resin composition according to claim 1 or claim 2, wherein the content ratio of the first structural unit to all the structural units constituting the polymer is 1 mol % or more and 20 mol % the following. A method for forming a resist pattern, comprising: a coating step of directly or indirectly coating a radiation-sensitive resin composition on a substrate; a step of exposing a resist film formed by the coating step; and The step of developing the exposed resist film, wherein the radiation-sensitive resin composition contains a polymer having a first structural unit represented by the following formula (1) and a polymer derived from an acid dissociable group The second structural unit of the (meth)acrylate; and a radiation-sensitive acid generator;

(In formula (1), R ¹ is a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms; R ² and R ³ are independently a hydroxyl group, a halogen atom, a nitro group, or a monovalent organic group having 1 to 20 carbon atoms. monovalent organic group; m is an integer of 0 to 9; n is an integer of 0 to 9; wherein, m+n is 9 or less; when m is 2 or more, a plurality of R ² are the same or different from each other; In the case of 2 or more, a plurality of R ³ are the same or different from each other). A polymer having a first structural unit represented by the following formula (1) and a second structural unit derived from a (meth)acrylate containing an acid dissociable group;

(In formula (1), R ¹ is a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms; R ² and R ³ are independently a hydroxyl group, a halogen atom, a nitro group, or a monovalent organic group having 1 to 20 carbon atoms. monovalent organic group; m is an integer of 0 to 9; n is an integer of 0 to 9; wherein, m+n is 9 or less; when m is 2 or more, a plurality of R ² are the same or different from each other; In the case of 2 or more, a plurality of R ³ are the same or different from each other).