JP2020008842A - Radiation-sensitive resin composition, method for forming resist pattern and polymer composition - Google Patents

Abstract

To provide a radiation-sensitive resin composition having excellent defect suppressing property and LWR performance while maintaining sensitivity, a method for forming a resist pattern and a polymer component.SOLUTION: The radiation-sensitive resin composition comprises a polymer component having a first structural unit including a phenolic hydroxyl group and a second structural unit including an acid dissociable group, and a radiation-sensitive acid generator, in which the polymer component satisfies expression (A) below. In expression (A), X1 represents a content percentage (mol%) of the first structural unit with respect to the whole structural units constituting the polymer component included in a fraction which is obtained by eluting the polymer component by gel permeation chromatography (GPC) for a retention time period until the cumulative area of the polymer component detected by a differential refractometer reaches 1% with respect to the whole area of the GPC elution curve; and X2 represents a content percentage (mol%) of the first structural unit with respect to the whole structural units constituting the polymer component.SELECTED DRAWING: None

Description

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

  Radiation-sensitive compositions used for microfabrication by lithography are irradiated with radiation such as far-ultraviolet rays such as ArF excimer laser light and KrF excimer laser light, electromagnetic waves such as extreme ultraviolet rays (EUV), and charged particle beams such as electron beams. An acid is generated in the exposed portion, and a chemical reaction using the acid as a catalyst causes a difference in the dissolution rate of the exposed portion and the unexposed portion in a developing solution, thereby forming a resist pattern on the substrate.

  Such a radiation-sensitive composition has good sensitivity to exposure light such as EUV and electron beams, and has not only excellent resolution but also excellent LWR (Line Width Roughness) performance, It is required to obtain an accurate pattern. In response to this requirement, various studies have been made on the structure of the polymer contained in the radiation-sensitive resin composition, and it is known that the performance can be improved by having a lactone structure such as a butyrolactone structure or a norbornane lactone structure. (See JP-A-11-212265, JP-A-2003-5375 and JP-A-2008-83370).

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

  However, at the present time when the miniaturization of the resist pattern is progressing to the level of the line width of 40 nm or less, the required level of the performance is further increased, and the conventional radiation-sensitive resin composition satisfies these requirements. I haven't been able to. In addition, recently, with the miniaturization of the resist pattern, it is particularly required that occurrence of defects in the resist pattern is suppressed.

  The present invention has been made based on the above circumstances, and an object of the present invention is to provide a radiation-sensitive resin composition, a resist pattern forming method, and a polymer composition which are excellent in defect suppression and LWR performance while maintaining sensitivity. To provide things.

（式（Ａ）中、Ｘ１は、示差屈折計で検出される上記重合体成分のゲルパーミエーションクロマトグラフィー（ＧＰＣ）溶出曲線の全面積に対して累積面積が１％となる保持時間までに溶出された画分に含まれる上記重合体成分を構成する全構造単位に対する第１構造単位の含有割合の値（モル％）である。Ｘ２は、上記重合体成分を構成する全構造単位に対する第１構造単位の含有割合の値（モル％）である。） The invention made to solve the above-mentioned problem is characterized in that in the same or different polymer, a first structural unit containing a phenolic hydroxyl group (hereinafter also referred to as “structural unit (I)”) and a first structural unit containing an acid-dissociable group are contained. A polymer component having two structural units (hereinafter also referred to as “structural unit (II)”) (hereinafter also referred to as “[A] polymer component”) and a radiation-sensitive acid generator (hereinafter referred to as “[B] (Hereinafter also referred to as “acid generator”), wherein the polymer component (A) satisfies the following formula (A).

(In the formula (A), X1 is eluted by the retention time when the cumulative area is 1% with respect to the total area of the gel permeation chromatography (GPC) elution curve of the polymer component detected by the differential refractometer. X2 is the content ratio (mol%) of the first structural unit to all structural units constituting the polymer component contained in the fraction obtained, and X2 is the first structural unit content to all structural units constituting the polymer component. It is the value (mol%) of the content ratio of the structural unit.)

（式（Ｂ）中、Ｘ１は、示差屈折計で検出される上記重合体成分のゲルパーミエーションクロマトグラフィー（ＧＰＣ）溶出曲線の全面積に対して累積面積が１％となる保持時間までに溶出された画分に含まれる上記重合体成分を構成する全構造単位に対する第１構造単位の含有割合の値（モル％）である。Ｘ２は、上記重合体成分を構成する全構造単位に対する第１構造単位の含有割合の値（モル％）である。） Another invention made in order to solve the above-mentioned problem is that, in the same or different polymer, a first structural unit containing a phenolic hydroxyl group (structural unit (I)) and a second structural unit containing an acid dissociable group ( A radiation-sensitive resin composition comprising a polymer component ([A] polymer component) having a structural unit (II)) and a radiation-sensitive acid generator ([B] acid generator), [A] The polymer component is characterized by satisfying the following formula (B).

(In the formula (B), X1 is eluted by the retention time when the cumulative area is 1% with respect to the total area of the gel permeation chromatography (GPC) elution curve of the polymer component detected by the differential refractometer. X2 is the content ratio (mol%) of the first structural unit to all structural units constituting the polymer component contained in the fraction obtained, and X2 is the first structural unit content to all structural units constituting the polymer component. It is the value (mol%) of the content ratio of the structural unit.)

  Yet another invention made in order to solve the above problems, a step of directly or indirectly coating the substrate with the radiation-sensitive resin composition, and a step of exposing the resist film formed by the coating step And a step of developing the exposed resist film.

（式（Ａ）中、Ｘ１は、示差屈折計で検出される上記重合体成分のゲルパーミエーションクロマトグラフィー（ＧＰＣ）溶出曲線の全面積に対して累積面積が１％となる保持時間までに溶出された画分に含まれる上記重合体成分を構成する全構造単位に対する第１構造単位の含有割合の値（モル％）である。Ｘ２は、上記重合体成分を構成する全構造単位に対する第１構造単位の含有割合の値（モル％）である。） Still another invention made to solve the above-mentioned problem is that [A] having a structural unit (I) containing a phenolic hydroxyl group and a structural unit (II) containing an acid dissociable group in the same or different polymer. A polymer composition containing a polymer component, wherein the polymer component (A) satisfies the following formula (A).

(In the formula (A), X1 is eluted by the retention time when the cumulative area is 1% with respect to the total area of the gel permeation chromatography (GPC) elution curve of the polymer component detected by the differential refractometer. X2 is the content ratio (mol%) of the first structural unit to all structural units constituting the polymer component contained in the fraction obtained, and X2 is the first structural unit content to all structural units constituting the polymer component. It is the value (mol%) of the content ratio of the structural unit.)

（式（Ｂ）中、Ｘ１は、示差屈折計で検出される上記重合体成分のゲルパーミエーションクロマトグラフィー（ＧＰＣ）溶出曲線の全面積に対する累積面積が１％となる保持時間までに溶出された画分に含まれる上記重合体成分を構成する全構造単位に対する第１構造単位の含有割合の値（モル％）である。Ｘ２は、上記重合体成分を構成する全構造単位に対する第１構造単位の含有割合の値（モル％）である。） Still another invention made to solve the above-mentioned problem is that [A] having a structural unit (I) containing a phenolic hydroxyl group and a structural unit (II) containing an acid dissociable group in the same or different polymer. A polymer composition containing a polymer component, wherein the polymer component [A] satisfies the following formula (B).

(In the formula (B), X1 was eluted by a retention time at which the cumulative area of the polymer component detected by a differential refractometer with respect to the total area of a gel permeation chromatography (GPC) elution curve was 1%. X2 is the content ratio (mol%) of the first structural unit to all structural units constituting the polymer component contained in the fraction, and X2 is the first structural unit to all structural units constituting the polymer component. Is the value of the content ratio (mol%).)

  According to the radiation-sensitive resin composition and the method for forming a resist pattern of the present invention, a resist pattern with few defects and a small LWR can be formed while maintaining sensitivity. The polymer composition of the present invention can be suitably used as a component of the radiation-sensitive resin composition. Therefore, they can be suitably used for the manufacture of semiconductor devices, for which further miniaturization is expected in the future.

FIG. 1 is a diagram showing a fraction (fraction A) eluted by a retention time at which a cumulative area with respect to the entire area of a gel permeation chromatography (GPC) elution curve when calculating X1 is 1% with respect to the entire area. .

<Radiation sensitive resin composition>
The radiation-sensitive resin composition contains [A] a polymer component and [B] an acid generator. The radiation-sensitive resin composition usually contains a solvent (hereinafter, also referred to as “[D] solvent”). In addition, the radiation-sensitive resin composition may contain an acid diffusion controller (hereinafter, also referred to as “[C] acid diffusion controller”) as a suitable component, and the effect of the present invention is not impaired. In the above, other optional components may be contained.

  The radiation-sensitive resin composition is excellent in defect suppression properties and LWR performance while maintaining sensitivity. The reason that the radiation-sensitive resin composition has the above-described configuration to achieve the above-described effects is not necessarily clear, but can be estimated as follows, for example. The present inventors have found that a high molecular weight component having a large content of the structural unit (I) causes defects. The present inventors have conducted intensive studies based on such findings, and as a result, in the same or different polymers, a structural unit (I) containing a phenolic hydroxyl group and a structural unit (II) containing an acid-dissociable group in the same polymer In the [A] polymer component having the following formula, the content ratio of the structural unit (I) is such that the value (X1) in the high molecular weight portion is smaller than the value (X2) in the entire [A] polymer component. It has been found that the above effects can be obtained by using. By using such a polymer component [A], the radiation-sensitive resin composition is considered to have improved defect suppression and LWR performance.

  Hereinafter, each component will be described.

<[A] polymer component>
[A] The polymer component is a polymer component having the structural unit (I) and the structural unit (II) in the same or different polymers. In the present specification, the “polymer component” includes not only one kind of polymer but also a mixture of plural kinds of polymers. That is, the polymer component [A] may be one kind of polymer having the structural unit (I) and the structural unit (II), and may be a polymer having at least the structural unit (I) and at least a structural unit (II). ) May be used. In addition, the polymer component [A] may include a polymer that does not include any of the structural unit (I) and the structural unit (II).

  Examples of the form of the polymer component (A) in the radiation-sensitive resin composition include (i) a form containing one type of polymer having a structural unit (I) and a structural unit (II), and (ii) A form which is a mixture containing a plurality of types of polymers having a structural unit (I) and a structural unit (II), (iii) a polymer having a structural unit (I) and a polymer having a structural unit (II) And (iv) both the forms (i) and (iii), and (v) both the forms (ii) and (iii). Among them, the above (i) or (ii) is preferable from the viewpoint of further improving the defect suppressing property and the LWR performance.

  [A] The polymer component satisfies the formula (A) as described later. Further, the polymer component (A) satisfies the formula (B) as described later. [A] The polymer component may have a structural unit other than the structural unit (I) and the structural unit (II). [A] The polymer component may have one or more kinds of each structural unit. Hereinafter, each structural unit will be described.

[Structural unit (I)]
The structural unit (I) is a structural unit containing a phenolic hydroxyl group. The “phenolic hydroxyl group” refers to not only a hydroxy group directly bonded to a benzene ring but also all hydroxy groups directly bonded to an aromatic ring. [A] When the polymer component has the structural unit (I), the hydrophilicity of the resist film can be increased, the solubility in a developing solution can be appropriately adjusted, and in addition, the resist pattern can be added to the substrate. Can be improved. In the case of KrF exposure, EUV exposure or electron beam exposure, the sensitivity of the radiation-sensitive resin composition can be further increased.

  Examples of the structural unit (I) include a structural unit represented by the following formula (1).

In the above formula (1), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ² is a single bond, -O -, - COO- *, or -CONH- is *. * Indicates a binding site to Ar. Ar is a group obtained by removing (p + q + 1) hydrogen atoms on an aromatic ring from an arene having 6 to 20 ring members. p is an integer of 0 to 10. When p is 1, R ³ is a monovalent organic group having 1 to 20 carbon atoms or a halogen atom. When p is 2 or more, a plurality of R ³ are the same or different and are each a monovalent organic group having 1 to 20 carbon atoms or a halogen atom, or two or more of a plurality of R ³ are combined with each other and Is a part of a ring structure having 4 to 20 ring members formed together with the carbon atom to be bonded. q is an integer of 1 to 11. However, p + q is 11 or less.

R ¹ is preferably a hydrogen atom or a methyl group, and more preferably a hydrogen atom, from the viewpoint of copolymerizability of the monomer giving the structural unit (I).

R ² is preferably a single bond or —COO- *, and more preferably a single bond.

  "Number of ring members" refers to the number of atoms constituting a ring of an alicyclic structure, an aromatic carbocyclic structure, an aliphatic heterocyclic structure, and an aromatic heterocyclic structure. Refers to the number of atoms.

  Examples of arenes having 6 to 20 ring members that provide Ar include, for example, benzene, naphthalene, anthracene, phenanthrene, tetracene, pyrene and the like. Of these, benzene or naphthalene is preferred, and benzene is more preferred.

“Organic group” refers to a group containing at least one carbon atom. As the monovalent organic group having 1 to 20 carbon atoms represented by R ³ , for example, a monovalent hydrocarbon group having 1 to 20 carbon atoms, a carbon-carbon or a bond end of this hydrocarbon group A group containing a divalent hetero atom-containing group, a group in which part or all of the hydrogen atoms of the hydrocarbon group and the group containing the divalent hetero atom-containing group are substituted with a monovalent hetero atom-containing group, or the like. No.

  The “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 “chain hydrocarbon group” refers to a hydrocarbon group that does not include a cyclic structure but is composed of only a chain structure, and includes both a linear hydrocarbon group and a branched hydrocarbon group. “Alicyclic hydrocarbon group” refers to a hydrocarbon group containing only an alicyclic structure as a ring structure and not containing an aromatic ring structure, and includes a monocyclic alicyclic hydrocarbon group and a polycyclic alicyclic group. Contains both hydrocarbon groups. However, it is not necessary to be constituted only by an alicyclic structure, and a part thereof may include a chain structure. “Aromatic hydrocarbon group” refers to a hydrocarbon group containing an aromatic ring structure as a ring structure. However, it is not necessary to be composed of only an aromatic ring structure, and a part thereof may include a chain structure or an alicyclic structure.

  The monovalent hydrocarbon group having 1 to 20 carbon atoms includes, for example, a monovalent linear hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and 6 carbon atoms. To 20 monovalent aromatic hydrocarbon groups.

Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms include an alkyl group such as a methyl group, an ethyl group, an n-propyl group, and an i-propyl group;
Alkenyl groups such as an ethenyl group, a propenyl group and a butenyl group;
Alkynyl groups such as an ethynyl group, a propynyl group and a butynyl group are exemplified.

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

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

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

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

  Examples of the monovalent hetero atom-containing group include a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, a hydroxy group, a carboxy group, a cyano group, an amino group and a sulfanyl group.

As R ³ , a monovalent hydrocarbon group is preferable, and an alkyl group is more preferable.

Examples of the ring structure having 4 to 20 ring members in which two or more of a plurality of R ³ are combined with each other include, for example, an alicyclic structure such as a cyclopentane structure, a cyclohexane structure, a cyclopentene structure, and a cyclohexene structure; a lactone structure; Examples include an aliphatic heterocyclic structure such as a cyclic ether structure.

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

  As q, 1-3 are preferable and 1 or 2 is more preferable.

  Examples of the structural unit (I) include structural units represented by the following formulas (1-1) to (1-12) (hereinafter, also referred to as “structural units (I-1) to (I-12)”) and the like. Is mentioned.

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

  Among these, the structural units (I-1), (I-2), (I-6) and (I-8) are preferred.

  The lower limit of the content of the structural unit (I) is preferably 10 mol%, more preferably 20 mol%, and still more preferably 30 mol%, based on all the structural units constituting the polymer component [A]. The upper limit of the content ratio is preferably 80 mol%, more preferably 70 mol%, and still more preferably 60 mol%. When the content ratio of the structural unit (I) is in the above range, the defect suppressing property and the LWR performance of the radiation-sensitive resin composition can be further improved.

[Structural unit (II)]
The structural unit (II) is a structural unit containing an acid dissociable group (hereinafter, also referred to as “acid dissociable group (a)”). An “acid dissociable group” is a group that substitutes a hydrogen atom such as a carboxy group, a sulfo group, and a phenolic hydroxyl group, and refers to a group that dissociates by the action of an acid. [B] The acid generated from the acid generator by exposure to light causes the dissociation of the acid dissociable group (a), and the solubility of the polymer component [A] in the developing solution is changed. Can be.

As the structural unit (II), for example, a structural unit represented by the following formula (2-1A), formula (2-1B), formula (2-1C), formula (2-2A) or formula (2-2B) And the like. ^-CR X ^R Y ^{R Z} that binds to the oxy oxygen atom derived from a carboxy group or a phenolic hydroxyl group, or a group ^-CR U ^R V containing an unsaturated alicyclic structure (OR ^W) is the acid-dissociable group (a) is there.

In the above formulas (2-1A), (2-1B), (2-1C), (2-2A) and (2-2B), ^RT is each independently a hydrogen atom, a fluorine atom, a methyl group. Or a trifluoromethyl group.

In the formulas (2-1A) and (2-1B), R ^X is each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^Y and R ^Z are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a group having 3 to 3 ring members formed by combining these groups together with the carbon atom to which they are bonded. It is part of 20 alicyclic structures.

In the formula (2-1C), ^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 which 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 respectively bonded.

In the formula (2-2A) and (2-2B), ^{R U} and ^{R V} are each independently a monovalent hydrocarbon group having a hydrogen atom or a carbon number of 1 to 20, ^{R W} are each independently, or a monovalent hydrocarbon group having 1 to 20 carbon atoms, the alicyclic structure composed ring members 3 to 20 together with the carbon atom to which R ^U and R ^V are combined they are bound to each other one either a part, or R ^U and R ^W are carbon atoms and R ^W that keyed R ^U, bonded to each other is part of the aliphatic heterocyclic structure consisting ring members 5 to 20 together with the oxygen atom bonded .

As a ^RT , a hydrogen atom or a methyl group is preferable from the viewpoint of copolymerizability of a monomer giving the structural unit (II).

Examples of 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 and R ^W include R of the above formula (1) ^{The same} groups as the hydrocarbon groups exemplified as ³ are exemplified.

Examples of the divalent hydrocarbon group having 1 to 20 carbon atoms represented by R ^D include a group obtained by removing one hydrogen atom from the monovalent hydrocarbon group exemplified as R ^{3 in the} above formula (1). Is mentioned.

As R ^X , an alkyl group or an aryl group is preferable.

As R ^Y and R ^Z , an alkyl group or an alicyclic saturated hydrocarbon group is preferable.

The alicyclic structure of ring members 3-20 which R ^Y and R ^Z or R ^U and R ^V constitutes, for example, cyclopropane structure, a cyclobutane structure, a cyclopentane structure, a cyclohexane structure, a norbornane structure, a saturated fat, such as adamantane structure Ring structure,
Examples thereof include unsaturated alicyclic structures such as a cyclopropene structure, a cyclobutene structure, a cyclopentene structure, a cyclohexene structure, and a norbornene structure.
Among these, a cyclopentane structure, a cyclohexane structure, a cyclohexene structure or an adamantane structure is preferred.

R ^D is R ^A, unsaturated alicyclic structure ring members 4-20 which constitute together with the carbon atom to which R ^B and R ^C are respectively coupled, for example cyclobutene structure, cyclopentene structure, cyclohexene structure, unsaturated such as norbornene structure An alicyclic structure is exemplified.

R ^U and the aliphatic heterocyclic structure ring members 5 to 20 in which R ^W is configured, for example, oxacyclobutane structure, oxacyclopentane structure, saturated oxygen-containing heterocyclic structure, such as oxacyclohexane structure; oxa-cyclobutene structure, oxa Examples include an unsaturated oxygen-containing heterocyclic structure such as a cyclopentene structure and an oxacyclohexene structure.

  As the structural unit represented by the above formula (2-1A), a structural unit derived from 1-alkylcycloalkane-1-yl (meth) acrylate and a structural unit derived from 1-arylcycloalkane-1-yl (meth) acrylate And a structural unit derived from 2-adamantylpropan-2-yl (meth) acrylate. As the structural unit represented by the above formula (2-1B), a structural unit derived from t-alkyloxystyrene is preferable. As the structural unit represented by the above formula (2-1C), a structural unit derived from cyclohexen-3-yl (meth) acrylate is preferable. As the structural unit represented by the above formula (2-2A), (1-ethoxy) ethoxy (meth) acrylate is preferable. As the structural unit represented by the above formula (2-2B), p- (1-ethoxy) ethoxystyrene is preferable.

  As the structural unit (II), a structural unit represented by the above formula (2-1A), (2-1B) or (2-1C) is preferable.

  The lower limit of the content ratio of the structural unit (II) is preferably 5 mol%, more preferably 10 mol%, still more preferably 15 mol%, based on all the structural units constituting the polymer component [A]. Molar% is particularly preferred. The upper limit of the content ratio is preferably 90 mol%, more preferably 80 mol%, further preferably 70 mol%, and particularly preferably 65 mol%. By setting the content to be in the above range, the sensitivity of the radiation-sensitive composition can be further increased, and as a result, defect suppression and LWR performance can be further improved.

[Other structural units]
[A] The polymer component may have one or more kinds of polymers other than the structural unit (I) and the structural unit (II). Examples of the other structural unit include a structural unit containing a lactone structure, a cyclic carbonate structure, a sultone structure or a combination thereof (hereinafter, also referred to as “structural unit (III)”), an alcoholic hydroxyl group other than structural unit (III) And a structural unit containing a non-acid-dissociable hydrocarbon group (hereinafter also referred to as a “structural unit (V)”).

  [A] The polymer component preferably has another structural unit. In the radiation-sensitive resin composition, when the polymer component [A] has another structural unit, the defect suppressing property and the LWR performance tend to be further improved. Hereinafter, the structural units (III) to (V) will be described.

(Structural unit (III))
The structural unit (III) is a structural unit containing a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination thereof. [A] When the polymer component has the structural unit (III), the solubility in a developer can be improved, and as a result, the defect suppression property and the LWR performance of the radiation-sensitive composition can be further improved. Can be. Further, the adhesion between the resist pattern and the substrate can be further improved.

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

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

  As the structural unit (III), a structural unit having a lactone structure is preferable, a structural unit having a norbornane lactone structure is more preferable, and a structural unit derived from cyanonorbornane lactone-yl (meth) acrylate is further preferable.

  [A] When the polymer component has the structural unit (III), the upper limit of the content ratio of the structural unit (III) is preferably 60 mol%, and more preferably 50 mol%, based on all the structural units constituting the polymer component. % Is more preferable, and 30 mol% is still more preferable. The lower limit of the content ratio is, for example, 1 mol%.

(Structural unit (IV))
The structural unit (IV) is a structural unit containing an alcoholic hydroxy group other than the structural unit (III). [A] When the polymer component has the structural unit (IV), the solubility in a developer can be improved, and as a result, the defect suppression property and the LWR performance of the radiation-sensitive composition can be further improved. Can be.

  As the structural unit (IV), for example, a hydroxy chain hydrocarbon group such as a structural unit derived from 3-hydroxyadamantan-1-yl (meth) acrylate, a structural unit derived from 2-hydroxyethyl (meth) acrylate, or a hydroxy group Hydroxyfluorine such as a structural unit containing an alicyclic hydrocarbon group, a structural unit derived from 2-hydroxy-2-trifluoromethyl-1,1,1-trifluoropropan-1-ylnorbornane-yl (meth) acrylate And a structural unit containing an alkylated alkyl group.

  [A] When the polymer component has the structural unit (IV), the upper limit of the content ratio of the structural unit (IV) is preferably 60 mol%, and more preferably 50 mol%, based on all the constituent units constituting the polymer component. % Is more preferred. The lower limit of the content ratio is, for example, 1 mol%.

(Structural unit (V))
The structural unit (V) is a structural unit containing a non-acid dissociable hydrocarbon group. [A] When the polymer component has the structural unit (V), the solubility in a developer can be improved, and as a result, the defect suppression property and the LWR performance of the radiation-sensitive composition can be further improved. Can be.

  Examples of the monomer giving the structural unit (V) include styrene, vinylnaphthalene, phenyl (meth) acrylate, benzyl (meth) acrylate, n-pentyl (meth) acrylate, cyclohexyl (meth) acrylate, and spiro [tetrahydronaphthalene- 1,5'-methylenebutyrolactone].

  [A] When the polymer component has the structural unit (V), the upper limit of the content ratio of the structural unit (V) is preferably 60 mol% based on all the structural units constituting the polymer component [A]. , 50 mol% is more preferable. The lower limit of the content ratio is, for example, 1 mol%.

  [A] The lower limit of the weight average molecular weight (Mw) of the polymer component in terms of polystyrene measured by gel permeation chromatography (GPC) is preferably 2,000, more preferably 3,000, still more preferably 4,000, and Is particularly preferred. The upper limit of Mw is preferably 50,000, more preferably 30,000, still more preferably 15,000, and particularly preferably 8,000. [A] By setting the Mw of the polymer component in the above range, the coating property of the radiation-sensitive resin composition can be further improved.

  [A] The lower limit of the degree of dispersion of the polymer component, that is, the lower limit of the ratio (Mw / Mn) of Mw to the number average molecular weight (Mn) in terms of polystyrene by GPC is preferably 1.1, more preferably 1.25, and 1. 4 is more preferred, and 1.5 is particularly preferred. As the upper limit of the degree of dispersion, 5 is preferable, 3 is more preferable, and 2 is further preferable. [A] By setting the Mw / Mn of the polymer component in the above range, the defect suppressing properties and LWR performance of the radiation-sensitive resin composition can be further improved.

The Mw and Mn of the polymer component in the present specification are values measured using gel permeation chromatography (GPC) under the following conditions.
GPC column: 2 “G2000HXL”, 1 “G3000HXL”, 1 “G4000HXL” from Tosoh Corporation Flow rate: 1.0 mL / min Eluent solvent: tetrahydrofuran Sample concentration: 1.0% by mass
Sample injection volume: 100 μL
Column temperature: 40 ° C
Detector: Differential refractometer Standard substance: Monodisperse polystyrene

[Formula (A)]
[A] The polymer component satisfies the following formula (A).

  In the above formula (A), X1 is a retention time at which the cumulative area is 1% with respect to the total area of the gel permeation chromatography (GPC) elution curve of the polymer component [A] detected by a differential refractometer. In the fraction (hereinafter also referred to as “fraction A”) contained in the fraction eluted up to and including the (A) content ratio (mol%) of the structural unit (I) to all the structural units constituting the polymer component. is there. X2 is a value (mol%) of a content ratio of the structural unit (I) with respect to all structural units constituting the polymer component [A].

X1 (mol%) is obtained by fractionating fraction A (see FIG. 1) corresponding to the area of 1% from the shorter retention time by preparative GPC under the following conditions, for example. The polymer component can be determined by measuring the content ratio of the structural unit (I) with respect to all structural units constituting the polymer component. In the preparative GPC, since fractionation is performed from high-molecular-weight components, fractions having a short retention time contain relatively more high-molecular-weight components than fractions having a long retention time. [A] When the polymer component is contained in the composition, the [A] polymer component is fractionated from the composition, and the obtained [A] polymer component is subjected to preparative GPC in the same manner as described above. X1 can be obtained by the following.
Preparative GPC column (“JAIGEL2.5H + 2H” of Nippon Kagaku Kogyo Co., Ltd.)
Flow rate: 4.0 mL / min Elution solvent: tetrahydrofuran Sample concentration: 3% by mass
Sample injection volume: 3 mL
Column temperature: 40 ° C
Detector: Differential refractometer

  The content ratio of the structural unit (I) in the polymer component is calculated, for example, by using PyGC-MS (Agilent Technologies) to calculate the area ratio of each monomer that gives each structural unit, and to calculate the area ratio of each monomer. Of the monomers giving the structural unit (I).

  X2 (mol%) can be determined by measuring the content ratio of the structural unit (I) with respect to all the structural units constituting the polymer component for the entire polymer component [A] without performing the above fractionation. . The content ratio of the structural unit (I) can be determined using, for example, PyGC-MS, as described above.

  As described above, in the polymer component [A], the content ratio (mol%) of the structural unit (I) is determined by the gel permeation chromatography elution curve detected by the differential refractometer in the polymer component [A]. In the above, the value (X1) in the high molecular weight portion where the cumulative area from the high molecular weight side is 1% with respect to the total area is smaller than the value (X2) in the entire polymer component [A].

  As a lower limit of X1, 25 mol% is preferred, 30 mol% is more preferred, and 35 mol% is still more preferred. As a maximum of X1, 60 mol% is preferred, 50 mol% is more preferred, and 45 mol% is still more preferred.

  The lower limit of the value obtained by subtracting X1 from X2 (X2−X1) is preferably 0.1 mol%, more preferably 1 mol%, and still more preferably 1.5 mol%. As a maximum of X2-X1, 10 mol% is preferred and 6 mol% is more preferred.

[Formula (B)]
[A] The polymer component satisfies the following formula (B).

  In the above formula (B), X1 and X2 have the same meaning as in the above formula (A).

  The lower limit of the ratio of X2 to X1 (X2 / X1) in the above formula (B) is preferably 1.01, more preferably 1.03, and even more preferably 1.05. The upper limit of X2 / X1 is preferably 1.20, more preferably 1.15.

  [A] In the gel permeation chromatography elution curve of the polymer component detected by a differential refractometer, the lower limit of the molecular weight of the high molecular weight portion where the cumulative area from the high molecular weight side is 1% of the total area is as follows: 3,000 is preferred, and 5,000 is more preferred. The upper limit of the molecular weight is preferably 15,000, more preferably 10,000.

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

[[A] Method for synthesizing polymer component]
[A] The polymer component is obtained by mixing a structural unit (I), a structural unit (II) and, if necessary, a monomer giving another structural unit at an appropriate molar ratio, and adding azobisisobutyronitrile It can be synthesized by performing polymerization by a known method in the presence of a polymerization initiator such as (AIBN) and in the presence or absence of a chain transfer agent such as 2-cyano-2-propyldodecyltrithiocarbonate. it can. When the structural unit (I) is a structural unit derived from hydroxystyrene, hydroxyvinylnaphthalene, or the like, these structural units obtain a polymer component using, for example, acetoxystyrene, acetoxyvinylnaphthalene, or the like as a monomer. It can be formed by hydrolyzing the polymer component in the presence of a base such as triethylamine. [A] The polymer component can be obtained by mixing a plurality of types of the polymer having the structural unit (I), the structural unit (II), and, if necessary, other structural units synthesized by the above method; Can also be obtained by mixing a polymer having the structural unit (I) and optionally other structural units with a polymer having the structural unit (II) and optionally other structural units. . Further, the polymer component [A] is separated from the polymer component having the structural unit (I), the structural unit (II) and, if necessary, other structural units synthesized by polymerizing by the above-mentioned known method. It can also be obtained by fractionating an appropriate portion using GPC or the like.

  [A] The polymer component may be a polymer component synthesized by polymerization by the above-described known method and purified by a known method. Examples of such purification include purification using a solvent, purification by preparative GPC, and the like. For purification using a solvent, for example, butyl acetate is added to dissolve the solid, washed with an aqueous sodium hydrogen carbonate solution, and then the organic layer is washed with ultrapure water, and the obtained concentrate is dropped in hexane. To solidify the polymer. For purification by preparative GPC, for example, using the preparative GPC described above, a fraction having a cumulative area corresponding to 25% with respect to the entire area of the GPC elution curve from the shorter retention time and a GPC The fraction corresponding to the cumulative area of 25% with respect to the total area of the elution curve was removed, and the remaining fraction (the fraction corresponding to the cumulative area of 25% to 75% with respect to the total area of the GPC elution area) was separated. And then using this as the [A] polymer component.

<[B] acid generator>
[B] The acid generator is a substance that generates an acid (hereinafter, also referred to as “acid (b)”) upon irradiation with radiation. Examples of the radiation include electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV, X-rays, and γ-rays; and charged particle beams such as electron beams and α-rays. [B] The acid (b) generated from the acid generator dissociates the acid dissociable group (a) of the polymer component [A] to form a carboxy group, a sulfo group, a phenolic hydroxyl group, and the like. Since the solubility of the coalesced component in the developer changes, a resist pattern can be formed from the radiation-sensitive resin composition. The content of the acid generator [B] in the radiation-sensitive resin composition may be a low molecular weight compound (hereinafter, also referred to as “[B] acid generator”) or a polymer such as the polymer component [A]. It may be a form incorporated as part of the union or both forms.

  The lower limit of the temperature at which the acid (b) dissociates the acid dissociable group (a) is preferably 80 ° C, more preferably 90 ° C, and even more preferably 100 ° C. As an upper limit of the above-mentioned temperature, 130 ° C is preferred, 120 ° C is more preferred, and 110 ° C is still more preferred. The lower limit of the time for the acid (b) to dissociate the acid dissociable group (a) is preferably 10 seconds, more preferably 1 minute. The upper limit of the time is preferably 10 minutes, more preferably 2 minutes.

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

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

  Examples of the onium salt compound include a sulfonium salt, a tetrahydrothiophenium salt, an iodonium salt, a phosphonium salt, a diazonium salt, a pyridinium salt and the like.

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

  Examples of the acid generator [B] that generates a sulfonic acid upon irradiation with a radiation include a compound represented by the following formula (3) (hereinafter, also referred to as “compound (3)”). [B] When the acid generator has the following structure, [A] the diffusion length of the generated acid (b) in the resist film by the interaction of the polymer component with the structural unit (I) is more moderate. It is considered to be shorter, and as a result, the defect suppression property and the LWR performance of the radiation-sensitive resin composition can be further improved.

In the above formula (3), R ^p1 is a monovalent group containing a ring structure having 5 or more ring members. R ^p2 is a divalent linking group. R ^p3 and R ^p4 are each independently a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. R ^p5 and R ^p6 are each independently a fluorine atom or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. n ^p1 is an integer of 0 to 10. ^np2 is an integer of 0 to 10. ^np3 is an integer of 0 to 10. However, n ^p1 + n ^p2 + n ^p3 is 1 or more and 30 or less. When n ^p1 is 2 or more, a plurality of R ^p2 are the same or different from each other. When n ^p2 is 2 or more, a plurality of R ^p3 are the same or different from each other, and a plurality of R ^p4 are the same or different from each other. When n ^p3 is 2 or more, a plurality of R ^p5 are the same or different from each other, and a plurality of R ^p6 are the same or different from each other. T ⁺ is a monovalent radiation-sensitive onium cation.

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

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

Examples of the aliphatic heterocyclic structure having 5 or more ring members include a lactone structure such as a hexanolactone structure and a norbornane lactone structure;
Sultone structures such as a hexanosultone structure and a norbornane sultone structure;
An oxygen atom-containing heterocyclic structure such as an oxacycloheptane structure or an oxanorbornane structure;
A heterocyclic structure containing a nitrogen atom such as an azacyclohexane structure or a diazabicyclooctane structure;
Examples thereof include a sulfur atom-containing heterocyclic structure such as a thiacyclohexane structure and a thiannorbornane structure.

  Examples of the aromatic ring structure having 5 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 an oxygen atom-containing heterocyclic structure such as a furan structure, a pyran structure, a benzofuran structure, and a benzopyran structure;
Examples include a nitrogen atom-containing heterocyclic structure such as a pyridine structure, a pyrimidine structure, and an indole structure.

The lower limit of the number of ring members of the ring structure of R ^p1 is preferably 6, more preferably 8, more preferably 9, and particularly preferably 10. The upper limit of the number of ring members is preferably 15, more preferably 14, more preferably 13, and particularly preferably 12. By setting the number of ring members in the above range, the diffusion length of the acid can be further appropriately reduced, and as a result, the LWR performance and the like of the radiation-sensitive resin composition can be further improved.

Some or all of the hydrogen atoms of the ring structure of R ^p1 may be substituted with a substituent. Examples of the substituent include a fluorine atom, a chlorine atom, a bromine atom, a halogen atom such as 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, Acyloxy group and the like. Of these, a hydroxy group is preferred.

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

Examples of the divalent linking group represented by R ^p2 include a carbonyl group, an ether group, a carbonyloxy group, a sulfide group, a thiocarbonyl group, a sulfonyl group, a divalent hydrocarbon group, and the like. Among these, a carbonyloxy group, a sulfonyl group, an alkanediyl group or a divalent alicyclic saturated hydrocarbon group is preferable, a carbonyloxy group or a divalent alicyclic saturated hydrocarbon group is more preferable, and a carbonyloxy group Or a norbornanediyl group is more preferred, and a carbonyloxy group is particularly preferred. When R ^p2 is a carbonyloxy group, the direction of the carbonyloxy group is not particularly limited. That is, the carbonyl carbon atom of the carbonyloxy group may be bonded to R ^p1 , or the oxy oxygen atom may be bonded to R ^p1 .

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

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

As ^np1 , 0-5 are preferable, 0-3 are more preferable, 0-2 are more preferable, and 0 or 1 is especially preferable.

The n ^p2, preferably 0-5, more preferably 0-2, more preferably 0 or 1, 0 is particularly preferred.

As a lower limit of ^np3 , 1 is preferable and 2 is more preferable. By setting ^np3 to 1 or more, the strength of the acid generated from the compound (3) can be increased, and as a result, the defect suppression property and the LWR performance of the radiation-sensitive resin composition can be further improved. . As an upper limit of ^np3 , 4 is preferable, 3 is more preferable, and 2 is further preferable.

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

Examples of the monovalent radiation-sensitive onium cation represented by T ⁺ include a cation represented by the following formula (r-a) (hereinafter, also referred to as “cation (r-a)”) and a compound represented by the following formula (r- b) (hereinafter, also referred to as “cation (rb)”), a cation represented by the following formula (rc) (hereinafter, also referred to as “cation (rc)”), and the like. No.

In the above formula (ra), ^RB3 and ^RB4 are each independently a monovalent organic group having 1 to 20 carbon atoms. b3 is an integer of 0 to 11. When b3 is 1, ^RB5 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. When b3 is 2 or more, a plurality of ^RB5s are the same or different and are each a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group or a halogen atom, or these groups are combined with each other. These are part of a ring structure having 4 to 20 ring members formed together with the carbon chain to which they are bonded. n _bb is an integer of 0 to 3.

The ^{R B3,} as the monovalent organic group ^{R B4} or having 1 to 20 carbon atoms represented by ^{R B5,} for example, a monovalent hydrocarbon group having 1 to 20 carbon atoms, the carbon of the hydrocarbon group - carbon-carbon Alternatively, a monovalent group (g) containing a divalent hetero atom-containing group at the terminal on the bond side, and part or all of the hydrogen atoms of the hydrocarbon group and the group (g) are substituted with a hetero atom-containing group. Monovalent groups and the like can be mentioned.

The R ^B3 and R ^B4, preferably a hydrocarbon radical monovalent unsubstituted hydrocarbon group or a hydrogen atom having 1 to 20 carbon atoms is substituted by a substituent, unsubstituted monovalent C6-18 Is more preferably an aromatic hydrocarbon group or an aromatic hydrocarbon group in which a hydrogen atom is substituted by a substituent, more preferably a substituted or unsubstituted phenyl group, and particularly preferably an unsubstituted phenyl group.

Examples of the substituent which may substitute a hydrogen atom of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by ^RB3 and ^RB4 include a substituted or unsubstituted 1 to 20 carbon atom. Divalent hydrocarbon group, -OSO ₂ -R ^k , -SO ₂ -R ^k , -OR ^k , -COOR ^k , -O-CO-R ^k , -O-R ^kk -COOR ^k , -R ^kk -CO -R ^k, or ^{-S-R k} are preferred. R ^k is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ^kk is a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms.

The R ^B5, 1 monovalent hydrocarbon group substituted or unsubstituted C _{^{1~20, -OSO 2 -R k, -SO}} 2 -R k, -OR k, -COOR k, -O-CO- R ^k , —O—R ^kk —COOR ^k , —R ^kk —CO—R ^k or —S—R ^k is preferred. R ^k is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ^kk is a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms.

In the above formula (rb), b4 is an integer of 0 to 9. When b4 is 1, ^RB6 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. When b4 is 2 or more, a plurality of ^RB6s are the same or different from each other and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group or a halogen atom, or these groups are combined with each other. These are part of a ring structure having 4 to 20 ring members formed together with the carbon chain to which they are bonded. b5 is an integer of 0 to 10. When b5 is 1, ^RB7 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. When b5 is 2 or more, a plurality of ^RB7s are the same or different and are each a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom, or these groups are combined with each other. These are part of a ring structure having 3 to 20 ring members formed together with the carbon atom or carbon chain to which they are bonded. _nb2 is an integer of 0 to 3. ^RB8 is a single bond or a divalent organic group having 1 to 20 carbon atoms. _nb1 is an integer of 0 to 2.

As the ^{R B6} and ^{R B7,} 1 monovalent hydrocarbon group substituted or unsubstituted C ^{1~20, -OR k, -COOR k,} -O-CO-R k, -O-R kk -COOR ^k or -R ^kk -CO-R ^k is preferred. R ^k is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ^kk is a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms.

In the above formula (rc), b6 is an integer of 0 to 5. When b6 is 1, ^RB9 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. When b6 is 2 or more, a plurality of ^RB9s are the same or different from each other and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom, or these groups are combined with each other. These are part of a ring structure having 4 to 20 ring members formed together with the carbon chain to which they are bonded. b7 is an integer of 0 to 5. When b7 is 1, ^RB10 is a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom. When b7 is 2 or more, a plurality of ^RB10s are the same or different from each other and are a monovalent organic group having 1 to 20 carbon atoms, a hydroxy group, a nitro group, or a halogen atom, or these groups are combined with each other. These are part of a ring structure having 4 to 20 ring members formed together with the carbon chain to which they are bonded.

Examples of the ^{R B9} and ^{R B10,} 1 monovalent hydrocarbon group having 1 to 20 carbon atoms substituted or _{^{unsubstituted, -OSO 2 -R k, -SO 2}} -R k, -OR k, -COOR k, - O-CO-R ^k , -OR ^kk -COOR ^k , -R ^kk -CO-R ^k , -SR ^k or a ring structure formed by combining two or more of these groups with each other. preferable. R ^k is a monovalent hydrocarbon group having 1 to 10 carbon atoms. R ^kk is a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms.

R ^B5, examples of the monovalent hydrocarbon group ^{R B6, R B7, R B9} or having 1 to 20 carbon atoms represented by ^{R B10,} a methyl group, an ethyl group, n- propyl group, n- butyl group A linear alkyl group;
branched alkyl groups such as i-propyl group, i-butyl group, sec-butyl group, t-butyl group;
Aryl groups such as phenyl, tolyl, xylyl, mesityl, and naphthyl;
And aralkyl groups such as benzyl group and phenethyl group.

The divalent organic group represented by R ^B8, for example, the formula (r-a) of the ^{R B3, R B4} and one hydrogen from a monovalent organic group having 1 to 20 carbon atoms exemplified as ^{R B5} Examples thereof include groups excluding atoms.

Examples of the substituent which may substitute a hydrogen atom of the hydrocarbon group represented by R ^B5 , R ^B6 , R ^B7 , R ^B9 or R ^B10 include, for example, a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. And the like, a halogen 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. Among these, a halogen atom is preferred, and a fluorine atom is more preferred.

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

B3 in the formula (r-a) is preferably 0 to 2, more preferably 0 or 1, and still more preferably 0. As n _bb , 0 or 1 is preferable, and 0 is more preferable. B4 in Formula (rb) is preferably 0 to 2, more preferably 0 or 1, and still more preferably 0. b5 is preferably 0 to 2, more preferably 0 or 1, and still more preferably 0. _nb2 is preferably 2 or 3, and more preferably 2. As n _b1 , 0 or 1 is preferable, and 0 is more preferable. As b6 and b7 in the formula (rc), 0 to 2 are preferable, 0 or 1 is more preferable, and 0 is further preferable.

As T ⁺ , among these, a cation (ra) is preferable, and a triphenylsulfonium cation is more preferable.

  [B] As the acid generator that generates sulfonic acid, for example, compounds represented by the following formulas (3-1) to (3-20) (hereinafter, “compounds (3-1) to (3) 3-20) "), as an acid generator for generating imidic acid, for example, compounds represented by the following formulas (4-1) to (4-3) (hereinafter, referred to as" compounds (4-1) to (4) 4-3) ").

In the above formulas (3-1) to (3-20) and (4-1) to (4-3), T ⁺ is a monovalent radiation-sensitive onium cation.

  Further, as the acid generator [B], the structure of an acid generator such as a polymer having a structural unit represented by the following formula (3 ') is incorporated as a part of the polymer component [A]. Coalescence.

In the above formula (3 ′), R ^p7 is a hydrogen atom or a methyl group. L ⁴ is a single bond or —COO— or a divalent carbonyloxy hydrocarbon group. R ^p8 is a fluorinated alkanediyl group having 1 to 10 carbon atoms. T ⁺ is a monovalent radiation-sensitive onium cation. When L ⁴ is —COO— or a divalent carbonyloxy hydrocarbon group, the carbonyl carbon atom of these groups is bonded to the carbon atom to which R ^p7 is bonded.

As R ^p7 , a methyl group is preferable from the viewpoint of copolymerizability of a monomer giving a structural unit represented by the above formula (3 ′).

The L ^4, preferably a divalent carbonyloxy hydrocarbon group, a carbonyl oxy alkanediyl group or carbonyloxy alkanediyl arene diyl group are more preferable.

As R ^p8 , a fluorinated alkanediyl group having 1 to 4 carbon atoms is preferable, a perfluoroalkanediyl group having 1 to 4 carbon atoms is more preferable, and a hexafluoropropanediyl group is further preferable.

  [B] As the acid generator, compound (3) is preferable, and compound (3-2), (3-11), (3-12), (3-13), (3-15) or (3- 20) is more preferred.

  When the acid generator [B] is an acid generator [B], the lower limit of the content of the acid generator [B] is preferably 0.1 part by mass with respect to 100 parts by mass of the polymer component [A]. 1 part by mass is more preferable, 5 parts by mass is more preferable, and 10 parts by mass is particularly preferable. As a maximum of the above-mentioned content, 50 mass parts is preferred, 40 mass parts is more preferred, 30 mass parts is still more preferred, and 25 mass parts is especially preferred. [B] By setting the content of the acid generator in the above range, the radiation-sensitive resin composition has improved sensitivity and developability, and as a result, defect suppression and LWR performance can be further improved. . [B] The acid generator may contain one type or two or more types.

<[C] Acid diffusion controller>
[C] The acid diffusion controller has the effect of controlling the diffusion phenomenon of the acid generated from the [B] acid generator or the like in the resist film by exposure, and suppressing an undesired chemical reaction in the non-exposed area. Further, the storage stability of the radiation-sensitive resin composition is improved, and the resolution as a resist is further improved. Further, a change in the line width of the resist pattern due to a change in the withdrawal time from exposure to development can be suppressed, and a radiation-sensitive resin composition having excellent process stability can be obtained. The [C] acid diffusion controller may be contained in the radiation-sensitive resin composition in the form of a low molecular weight compound (hereinafter, also referred to as “[C] acid diffusion controller” as appropriate) or the [A] polymer component. Or a form incorporated as a part of the polymer.

  [C] Examples of the acid diffusion controller include a nitrogen atom-containing compound and a photo-degradable base that is exposed to light to generate a weak acid.

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

  Examples of the photodisintegrable base include a compound containing an onium cation decomposed by exposure to light and an anion of a weak acid. In the photodegradable base, a weak acid is generated from the proton generated by the decomposition of the onium cation and the anion of the weak acid in the exposed portion, so that the acid diffusion controllability is reduced.

Examples of the photodisintegrable base include a compound represented by the following formula, a compound represented by the above formula (3) (where n ^p3 is 0, R ^p3 and R ^p4 are each independently a hydrogen atom or a carbon atom And a monovalent hydrocarbon group of 1 to 20).

  When the radiation-sensitive resin composition contains the [C] acid diffusion controller, the lower limit of the content of the [C] acid diffusion controller is 0.1 to 100 parts by mass of the [A] polymer component. 1 part by mass is preferable, 0.5 part by mass is more preferable, and 1 part by mass is further preferable. As a maximum of the above-mentioned content, 20 mass parts is preferred, 10 mass parts is more preferred, and 5 mass parts is still more preferred.

  When the radiation-sensitive resin composition contains the acid diffusion controller [C], the lower limit of the content of the acid diffusion controller [C] is 1 mol per 100 mol% of the acid generator [B]. % Is preferable, 5 mol% is more preferable, and 10 mol% is further preferable. As a maximum of the above-mentioned content, 250 mol% is preferred, 150 mol% is more preferred, and 100 mol% is still more preferred.

  [C] By controlling the content of the acid diffusion controller in the above range, the defect suppressing property and the LWR performance of the radiation-sensitive resin composition can be further improved. [C] The acid diffusion controller may contain one type or two or more types.

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

  [D] The solvent includes, for example, alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, hydrocarbon solvents and the like.

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;
An alicyclic monoalcohol solvent having 3 to 18 carbon atoms such as cyclohexanol;
A polyhydric alcohol solvent having 2 to 18 carbon atoms such as 1,2-propylene glycol;
Examples thereof include polyhydric alcohol partial ether solvents having 3 to 19 carbon atoms such as 1-methoxy-2-propanol.

Examples of the ether solvent 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;
Examples include aromatic ring-containing ether solvents such as diphenyl ether and anisole.

Examples of the ketone solvent include 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:
Examples thereof include 2,4-pentanedione, acetonylacetone, and acetophenone.

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

Examples of the ester solvent include monocarboxylic acid ester solvents such as n-butyl acetate and ethyl lactate;
Polyhydric alcohol carboxylate solvents such as propylene glycol acetate;
Polyhydric alcohol partial ether carboxylate solvents such as propylene glycol monomethyl ether acetate;
Polyvalent carboxylic acid diester solvents such as diethyl oxalate;
Examples thereof include carbonate solvents such as dimethyl carbonate and diethyl carbonate.

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

  Of these, ester solvents and / or ketone solvents are preferred, polyhydric alcohol partial ether carboxylate solvents and / or cyclic ketone solvents are more preferred, and propylene glycol monomethyl ether acetate and / or cyclohexanone are even more preferred. [D] The solvent may contain one type or two or more types.

<Other optional components>
Other optional components include, for example, surfactants. The radiation-sensitive resin composition may contain one or more other optional components.

  Surfactants have the effect of improving coatability, striation, developability, and the like. Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, and polyethylene glycol dilaurate. Nonionic surfactants such as stearate; as commercial products, KP341 (Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75; 95 (Kyoeisha Chemical Co., Ltd.), F-Top EF301, EF303, EF352 (Tokchem Products, Ltd.), Megafac F171, F173 (DIC, DIC), Florard FC430, FC431 (above, Sumitomo 3M Limited), Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 ( As mentioned above, Asahi Glass Co., Ltd.) can be mentioned.

  When the radiation-sensitive resin composition contains a surfactant, the upper limit of the surfactant content is preferably 2 parts by mass with respect to 100 parts by mass of the polymer component (A). The lower limit of the content is, for example, 0.1 part by mass.

<Method of preparing radiation-sensitive resin composition>
The radiation-sensitive resin composition is prepared by mixing arbitrary components such as a polymer component [A], an acid generator [B], a solvent [D] and, if necessary, an acid diffusion controller [C] at a predetermined ratio. Preferably, it can be prepared by filtering the obtained mixture with a membrane filter having a pore size of about 0.2 μm.

  The radiation-sensitive resin composition can be used both for forming a positive pattern using an alkali developer and for forming a negative pattern using a developer containing an organic solvent.

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

  According to the method for forming a resist pattern, since the radiation-sensitive resin composition described above is used, a resist pattern with few defects and a small LWR can be formed while maintaining sensitivity. Hereinafter, each step will be described.

[Coating process]
In this step, the radiation-sensitive resin composition is applied directly or indirectly to the substrate. As a result, a resist film is formed. Examples of the substrate include conventionally known substrates such as a silicon wafer, silicon dioxide, and a wafer coated with aluminum. In the case where the radiation-sensitive resin composition is applied to the substrate indirectly, for example, the radiation-sensitive resin composition is applied to an antireflection film formed on the substrate. Examples of such an antireflection film include an organic or inorganic antireflection film disclosed in Japanese Patent Publication No. 6-12452 and Japanese Patent Application Laid-Open No. 59-93448. Examples of the coating method include spin coating, spin coating, roll coating, and the like. After the application, if necessary, a pre-bake (PB) may be performed to volatilize the solvent in the coating film. The lower limit of the PB temperature is preferably 60 ° C, more preferably 80 ° C. As an upper limit of the above-mentioned temperature, 150 ° C is preferred and 140 ° C is more preferred. The lower limit of the PB time is preferably 5 seconds, and more preferably 10 seconds. As a lower limit of the above-mentioned time, 600 seconds are preferred and 300 seconds are more preferred. The lower limit of the average thickness of the formed resist film is preferably 10 nm, more preferably 20 nm. The upper limit of the average thickness is preferably 1,000 nm, more preferably 500 nm.

[Exposure process]
In this step, the resist film formed in the coating step is exposed. This exposure is performed by irradiating exposure light via a photomask (in some cases, via an immersion medium such as water). Examples of the exposure light include, for example, electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, EUV, X-rays, and γ-rays; and charged particle beams such as electron beams and α-rays, depending on the line width of the target pattern. Can be Among them, far ultraviolet rays, EUV or electron beams are preferable, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), EUV or electron beam are more preferable, and ArF excimer laser light, EUV or electron beam is preferable. Even more preferred is EUV or electron beam.

  After the above-mentioned exposure, post-exposure bake (PEB) is performed, and in the exposed portion of the resist film, [B] an acid dissociable group of a polymer component or the like due to an acid generated from an acid generator or the like by the exposure. Preferably, the dissociation of (a) is promoted. By this PEB, the difference in solubility in the developing solution between the exposed part and the unexposed part can be increased. The lower limit of the temperature of PEB is preferably 50 ° C, more preferably 80 ° C, and still 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 step]
In this step, the exposed resist film is developed. Thereby, a predetermined resist pattern can be formed. After development, it is common to wash with water or a rinse solution such as alcohol and dry. The developing method in the developing step may be alkali developing or organic solvent developing.

  In the case of alkali development, examples of a developer used for development include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n- Propylamine, triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, 1 And an aqueous alkaline solution in which at least one kind of an alkaline compound such as 2,5-diazabicyclo- [4.3.0] -5-nonene is dissolved. Of these, a TMAH aqueous solution is preferable, and a 2.38% by mass TMAH aqueous solution is more preferable.

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

  As a developing method, for example, a method of dipping a substrate in a bath filled with a developing solution for a certain time (dip method), a method of raising the developing solution on the substrate surface by surface tension and stopping for a certain time (paddle method) ), A method of spraying a developing solution onto a substrate surface (spray method), a method of continuously applying a developing solution while scanning a developing solution application nozzle at a constant speed on a substrate rotating at a constant speed (dynamic dispense method). And the like.

  Examples of the pattern formed by the resist pattern forming method include a line-and-space pattern and a hole pattern.

<Polymer composition>
The polymer composition contains the polymer component (A). In the present specification, the “polymer composition” includes not only a mixture of plural kinds of polymers but also one kind of polymer. The polymer component [A] has been described as the polymer component [A] contained in the radiation-sensitive resin composition described above.

  Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. Physical properties in the examples were measured as follows.

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

[Measurement of X1 and X2]
Using a preparative GPC column (“JAIGEL2.5H + 2H” of Nippon Kagaku Kogyo Co., Ltd.), flow rate: 4.0 mL / min, elution solvent: tetrahydrofuran, sample concentration: 3% by mass, sample injection amount: 3 mL, column temperature: 40 ° C., Detector: Under the analysis conditions of the differential refractometer, a fraction corresponding to an area of 1% was collected from the one having the shorter retention time, and the polymer component contained in the collected fraction was analyzed by Agilent Technologies. The area ratio of each monomer which gives each structural unit was calculated using PyGC-MS of the company. The area ratio of the hydroxystyrene unit in the area ratio of each monomer was defined as X1 (mol%). On the other hand, the same analysis was performed by PyGC-MS on the entire polymer component without fractionation, and the area ratio of hydroxystyrene units was defined as X2 (mol%).

<[A] Synthesis of polymer component>
[A] The monomers used in the synthesis of the polymer component are shown below.

  In the following examples, unless otherwise specified, the numerical value of parts by mass is a value with the total mass of the used monomers being 100 parts by mass, and the numerical value of mol% is the total number of moles of the used monomers. Is 100 mol%.

[Example 1] (Synthesis of polymer component (A-1))
The monomer (M-1), the monomer (M-4) and the monomer (M-9) have a content ratio (molar ratio) of each structural unit in the finally obtained polymer of 35. / 45/20 was dissolved in 60 parts by mass of 1-methoxy-2-propanol. Next, 3.5 mol% of 2-cyano-2-propyldodecyltrithiocarbonate as a chain transfer agent with respect to all monomers and azobisisobutyronitrile (AIBN) as a polymerization initiator were added. 0.7 mol% was added to the monomer to prepare a monomer solution. After the monomer solution was purged with nitrogen for 30 minutes, the monomer solution was heated to 80 ° C. while stirring, and the time when the temperature of the monomer solution reached 80 ° C. was defined as the start time of the polymerization reaction. For 6 hours. After the completion of the polymerization reaction, with the temperature of the polymerization reaction solution kept at 80 ° C, 14.3 mol% of AIBN based on all monomers and 17.8 mol% of tert- A solution of dodecanethiol dissolved in 50 parts by mass of 1-methoxy-2-propanol was added dropwise over 15 minutes. After completion of the dropwise addition, the mixture was heated at 80 ° C. for 2 hours to perform terminal treatment, and then the polymerization reaction solution was cooled with water and cooled to 30 ° C. or less.

  The cooled polymerization reaction solution was added to 500 parts by mass of hexane based on 100 parts by mass of the polymerization reaction solution, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 100 parts by mass of hexane with respect to 100 parts by mass of the polymerization reaction solution, filtered, and dissolved in 300 parts by mass of 1-methoxy-2-propanol. Next, 500 parts by mass of methanol, 50 parts by mass of triethylamine and 10 parts by mass of ultrapure water were added, and a hydrolysis reaction was carried out at 70 ° C. for 6 hours while stirring.

  After completion of the reaction, the remaining solvent was distilled off, and the obtained solid was dissolved in 100 parts by mass of acetone. The polymer was solidified by dropping into 500 parts by mass of water, and the obtained solid was separated by filtration. Further, 3,000 parts by mass of butyl acetate was added to dissolve the solid, and the solid was washed with 3,000 parts by mass of a 5% by mass aqueous sodium hydrogen carbonate solution. Next, the organic layer was washed three times with 3,000 parts by mass of ultrapure water, and then concentrated to 300 parts by mass with respect to all monomers. The obtained concentrate was dropped into hexane of 5 times mass to coagulate the polymer, and dried at 50 ° C. for 12 hours to synthesize a white powdery polymer component (A-1).

[Examples 2 to 6] (Synthesis of Polymer Components (A-2) to (A-6))
Polymer components (A-2) to (A-6) were synthesized in the same manner as in Example 1 except that monomers having the types and the use ratios shown in Table 1 below were used. "-" Shown in Table 1 indicates that the corresponding monomer was not used.

[Example 7] (Synthesis of polymer component (A-7))
The monomer (M-1), the monomer (M-4) and the monomer (M-9) have a content ratio (molar ratio) of each structural unit in the finally obtained polymer of 35. / 45/20 in 200 parts by mass of 1-methoxy-2-propanol. Next, AIBN as a polymerization initiator was added in an amount of 5 mol% based on all monomers to prepare a monomer solution. On the other hand, after the empty reaction vessel was purged with nitrogen for 30 minutes, 100 parts by mass of 1-methoxy-2-propanol was added, and the mixture was heated to 80 ° C. with stirring. Next, the monomer solution prepared above was added dropwise over 3 hours, and then further heated at 80 ° C. for 3 hours to carry out a polymerization reaction for a total of 6 hours. After the completion of the polymerization reaction, the polymerization reaction solution was cooled with water and cooled to 30 ° C. or lower.

  The cooled polymerization reaction solution was added to 500 parts by mass of hexane based on 100 parts by mass of the polymerization reaction solution, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 100 parts by mass of hexane with respect to 100 parts by mass of the polymerization reaction solution, then, filtered and dissolved in 300 parts by mass of 1-methoxy-2-propanol. Next, 500 parts by mass of methanol, 50 parts by mass of triethylamine and 10 parts by mass of ultrapure water were added, and a hydrolysis reaction was carried out at 70 ° C. for 6 hours while stirring.

  After completion of the reaction, the remaining solvent was distilled off, and the obtained solid was dissolved in 100 parts by mass of acetone. The polymer was solidified by dropping into 500 parts by mass of water, and the obtained solid was separated by filtration. Further, 3,000 parts by mass of butyl acetate was added to dissolve the solid, and the solid was washed with 3,000 parts by mass of a 5% by mass aqueous sodium hydrogen carbonate solution. Next, the organic layer was washed three times with 3,000 parts by mass of ultrapure water, and then concentrated to 300 parts by mass with respect to all monomers. The obtained concentrate was dropped into hexane of 5 times mass to coagulate the polymer, and dried at 50 ° C for 12 hours to synthesize a white powdery polymer component (A-7).

[Examples 8 to 10] (Synthesis of polymer components (A-8) to (A-10))
Polymer components (A-8) to (A-10) were synthesized in the same manner as in Example 7, except that monomers having the types and content ratios shown in Table 1 below were used.

[Example 11] (Purification of polymer component (A-1) by preparative GPC)
For the polymer component (A-1), using a preparative GPC of GL Sciences Co., Ltd., a fraction having a cumulative area corresponding to 25% with respect to the entire area of the GPC elution curve from the shorter retention time, and a retention time The fraction corresponding to the cumulative area of 25% with respect to the total area of the GPC elution curve was removed from the longest, and the remaining fraction (the cumulative area of the GPC elution area with respect to the total area of 25% to 75% corresponding to the total area). (Fraction) was taken as a polymer component (A-1P). The total area of the GPC elution curve is defined as 100%.

[Reference Synthesis Examples 1 and 2] (Synthesis of Polymer Components (A-11) to (A-12))
Polymer components (A-11) to (A-12) were synthesized in the same manner as in Example 7, except that monomers having the types and content ratios shown in Table 1 below were used.

[Examples 12 to 14] (Synthesis of polymer components (A-13) to (A-15))
Polymer components (A-13) to (A-15) were synthesized in the same manner as in Example 7, except that monomers having the types and content ratios shown in Table 1 below were used.

[Comparative Synthesis Example 1] (Synthesis of polymer component (a-1))
The monomer (M-1), the monomer (M-4) and the monomer (M-9) have a content ratio (molar ratio) of each structural unit in the finally obtained polymer of 35. / 45/20 was dissolved in 60 parts by mass of 1-methoxy-2-propanol. Next, 3.5 mol% of 2-cyano-2-propyldodecyltrithiocarbonate as a chain transfer agent with respect to all the monomers and AIBN as a polymerization initiator of 0.1 mol with respect to all the monomers were used. 7 mol% was added to prepare a monomer solution. This monomer solution was purged with nitrogen for 30 minutes, and then heated to 80 ° C. with stirring. The time when the temperature of the monomer solution reached 80 ° C. was defined as the start time of the polymerization reaction, and the polymerization reaction was performed for 6 hours. . After the completion of the polymerization reaction, while keeping the temperature of the polymerization reaction solution at 80 ° C., 14.3 mol% of AIBN based on all monomers and 17.8 mol% of tert-dodecane based on all monomers. A solution of thiol dissolved in 60 parts by mass of 1-methoxy-2-propanol was added dropwise over 15 minutes. After completion of the dropwise addition, the mixture was heated at 80 ° C. for 2 hours to perform a terminal treatment, and then the polymerization reaction solution was cooled with water to 30 ° C. or lower.

  The cooled polymerization reaction solution was added to 500 parts by mass of hexane based on 100 parts by mass of the polymerization reaction solution, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 100 parts by mass of hexane with respect to 100 parts by mass of the polymerization reaction solution, then, filtered and dissolved in 300 parts by mass of 1-methoxy-2-propanol. Next, 500 parts by mass of methanol, 50 parts by mass of triethylamine and 10 parts by mass of ultrapure water were added, and a hydrolysis reaction was carried out at 70 ° C. for 6 hours while stirring.

  After completion of the reaction, the remaining solvent was distilled off, and the obtained solid was dissolved in 100 parts by mass of acetone. The polymer was solidified by dropping into 500 parts by mass of water, and the obtained solid was separated by filtration. The polymer component (a-1) in the form of a white powder was synthesized by drying at 50 ° C. for 12 hours.

[Comparative Synthesis Examples 2 to 4] (Synthesis of Polymer Components (a-2) to (a-4))
Polymer components (a-2) to (a-4) were synthesized in the same manner as in Comparative Synthesis Example 1, except that monomers having the types and content ratios shown in Table 1 below were used.

[Comparative Synthesis Example 5] (Synthesis of polymer component (a-5))
The monomer (M-1), the monomer (M-4) and the monomer (M-11) have a content ratio (molar ratio) of each structural unit in the finally obtained polymer of 50. / 30/20 in 200 parts by mass of 1-methoxy-2-propanol. Next, AIBN as a polymerization initiator was added in an amount of 5 mol% based on all monomers to prepare a monomer solution. On the other hand, after the empty reaction vessel was purged with nitrogen for 30 minutes, 100 parts by mass of 1-methoxy-2-propanol was added, and the mixture was heated to 80 ° C. with stirring. Next, the monomer solution prepared above was added dropwise over 3 hours, and then heated at 80 ° C. for another 3 hours to carry out a polymerization reaction for a total of 6 hours. After the completion of the polymerization reaction, the polymerization reaction solution was cooled with water and cooled to 30 ° C. or lower.

  The cooled polymerization reaction solution was added to 500 parts by mass of hexane based on 100 parts by mass of the polymerization reaction solution, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 100 parts by mass of hexane with respect to 100 parts by mass of the polymerization reaction solution, then filtered and dissolved in 300 parts by mass of 1-methoxy-2-propanol. Next, 500 parts by mass of methanol, 50 parts by mass of triethylamine and 10 parts by mass of ultrapure water were added, and a hydrolysis reaction was carried out at 70 ° C. for 6 hours while stirring.

  After completion of the reaction, the remaining solvent was distilled off, and the obtained solid was dissolved in 100 parts by mass of acetone. The polymer was coagulated by dropping into 500 parts by mass of water, and the obtained solid was separated by filtration and dried at 50 ° C. for 12 hours to synthesize a white powdery polymer component (a-5).

[Comparative Synthesis Examples 6 to 8] (Synthesis of Polymer Components (a-6) to (a-8))
Polymer components (a-6) to (a-8) were synthesized in the same manner as in Comparative Synthesis Example 5 except that monomers having the types and content ratios shown in Table 1 below were used.

<Preparation of radiation-sensitive resin composition>
The [B] acid generator, [C] acid diffusion controller and [D] solvent used in the preparation of the radiation-sensitive resin composition are shown below.

[[B] acid generator]
B-1 to B-6: compounds represented by the following formulas (B-1) to (B-6)

[C] Acid diffusion controller
C-1 to C-4: compounds represented by the following formulas (C-1) to (C-4)

[[D] solvent]
D-1: Propylene glycol monomethyl acetate acetate D-2: Cyclohexanone

[Example 15]
[A] 100 parts by mass of (A-1) as a polymer component, [B] 20 parts by mass of (B-1) as an acid generator, and [C] (C-1) as an acid diffusion controller are described above. 30 mol% with respect to (B-1) and 4,800 parts by mass of (D-1) and 2,000 parts by mass of (D-2) as a solvent [D] were mixed, and the resulting mixture was treated with a pore size of 0. A radiation-sensitive resin composition (R-1) was prepared by filtration with a 0.2 μm membrane filter.

[Examples 16 to 36 and Comparative Examples 1 to 10]
Except for using each component having the kind and content shown in Table 2 below, the same procedures as in Example 15 were carried out to obtain radiation-sensitive resin compositions (R-2) to (R-22) and (CR-1). ) To (CR-10) were prepared. When preparing the radiation-sensitive resin composition (R-19), the mixture of (A-11) 50 parts by mass and (A-12) 50 parts by mass was subjected to measurement of X1 and X2. <X2, and X2 / X1> 1.0. In Example 33, 100 parts by mass of the above mixture was used as the polymer component [A].

<Formation of resist pattern>
A radiation-sensitive resin composition prepared above using a spin coater (“CLEAN TRACK ACT8” manufactured by Tokyo Electron Limited) on the surface of a 12-inch silicon wafer coated with AL412 (Brewer Science) having a thickness of 20 nm. Was applied, PB was performed at 130 ° C. for 60 seconds, and then cooled at 23 ° C. for 30 seconds to form a 55-nm-thick resist film. Next, the resist film was irradiated with EUV light using an EUV exposure apparatus (model “NXE3300”, manufactured by ASML, NA = 0.33, illumination condition: Conventionals = 0.89, mask imecDEFECT32FFR02). Next, PEB was performed at 110 ° C. for 60 seconds, then cooled at 23 ° C. for 30 seconds, and developed using a 2.38 mass% TMAH aqueous solution at 23 ° C. for 30 seconds to form a positive 32 nm line and space pattern. .

<Evaluation>
The defect suppression properties, sensitivity, and LWR performance of the radiation-sensitive resin composition were evaluated by the following methods. For measuring the length of the resist pattern in sensitivity and LWR performance, a high-resolution FEB length measuring device (“CG5000” manufactured by Hitachi High-Technologies Corporation) was used.

[Defect suppression]
With respect to the formed line and space pattern, the number of defects (pieces / cm ² ) was measured by a defect inspection device (“KLA2925” manufactured by KLA-Tencor). The defect suppressing property can be evaluated as “good” when the number is 20 pieces / cm ² or less, and “bad” when the number exceeds 20 pieces / cm ² .

[sensitivity]
In forming the resist pattern, the exposure amount for forming a 32 nm line and space pattern was defined as the optimum exposure amount, and the optimum exposure amount was defined as the sensitivity (mJ / cm ² ).

[LWR performance]
The formed 32 nm line and space pattern was observed from above the pattern, the line width was measured at an arbitrary point at a total of 50 points, and a 3 sigma value was obtained from the distribution of the measured values. ). The LWR performance indicates that the smaller the value, the smaller the variation in line width and the better. The LWR performance can be evaluated as “good” when it is 3.1 nm or less, and “bad” when it exceeds 3.1 nm.

  As is evident from the results in Table 3, the radiation-sensitive resin compositions of the examples were all excellent in defect suppression and LWR performance. Further, the radiation-sensitive resin composition using the polymer component (A-1P) obtained by purification by preparative GPC also showed the same defect suppression properties and LWR performance.

According to the radiation-sensitive resin composition and the method for forming a resist pattern of the present invention, a resist pattern with few defects and a small LWR can be formed while maintaining sensitivity. The polymer component of the present invention can be suitably used as a component of the radiation-sensitive resin composition. Therefore, they can be suitably used for the manufacture of semiconductor devices, for which further miniaturization is expected in the future.

Claims (9)

In the same or different polymers, a polymer component having a first structural unit containing a phenolic hydroxyl group and a second structural unit containing an acid-dissociable group,
A radiation-sensitive resin composition containing a radiation-sensitive acid generator and
A radiation-sensitive resin composition, wherein the polymer component satisfies the following formula (A).

(In the formula (A), X1 is eluted by the retention time when the cumulative area is 1% with respect to the total area of the gel permeation chromatography (GPC) elution curve of the polymer component detected by the differential refractometer. X2 is the content ratio (mol%) of the first structural unit to all structural units constituting the polymer component contained in the fraction obtained, and X2 is the first structural unit content to all structural units constituting the polymer component. It is the value (mol%) of the content ratio of the structural unit.) In the same or different polymers, a polymer component having a first structural unit containing a phenolic hydroxyl group and a second structural unit containing an acid-dissociable group,
A radiation-sensitive resin composition containing a radiation-sensitive acid generator and
A radiation-sensitive resin composition, wherein the polymer component satisfies the following formula (B).

(In the formula (B), X1 is eluted by the retention time when the cumulative area is 1% with respect to the total area of the gel permeation chromatography (GPC) elution curve of the polymer component detected by the differential refractometer. X2 is the content ratio (mol%) of the first structural unit to all structural units constituting the polymer component contained in the fraction obtained, and X2 is the first structural unit content to all structural units constituting the polymer component. It is the value (mol%) of the content ratio of the structural unit.) The radiation-sensitive resin composition according to claim 1 or 2, wherein the first structural unit is represented by the following formula (1).

(In the formula (1), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ² is a single bond, —O—, —COO- *, or —CONH- *. * Indicates a binding site to Ar, where Ar is a group obtained by removing hydrogen atoms on (p + q + 1) aromatic rings from an arene having 6 to 20 ring members, and p is an integer of 0 to 10. When p is 1, R ³ is a monovalent organic group having 1 to 20 carbon atoms or a halogen atom, and when p is 2 or more, a plurality of R ³ are the same or different and have 1 to 20 carbon atoms. It is a monovalent organic group or a halogen atom, or a part of a ring structure having 4 to 20 ring members in which two or more of a plurality of R ³ are combined with each other and formed together with a carbon atom to which they are bonded. Q is an integer of 1 to 11, provided that p + q is 11 or less.) The claim 1, wherein the second structural unit is represented by the following formula (2-1A), formula (2-1B), formula (2-1C), formula (2-2A), or formula (2-2B). The radiation-sensitive resin composition according to claim 2 or 3.

(In the formulas (2-1A), (2-1B), (2-1C), (2-2A), and (2-2B), ^RT is each independently a hydrogen atom, a fluorine atom, a methyl group. Or a trifluoromethyl group.
In the formulas (2-1A) and (2-1B), R ^X is each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^Y and R ^Z are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or a group having 3 to 3 ring members formed by combining these groups together with the carbon atom to which they are bonded. It is part of 20 alicyclic structures.
In the formula (2-1C), ^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 which 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 respectively bonded.
Wherein (2-2A) and (2-2B), ^{R U} and ^{R V} are each independently a monovalent hydrocarbon group having a hydrogen atom or a carbon number of 1 to 20, ^{R W} are each independently to either a monovalent hydrocarbon group having 1 to 20 carbon atoms, a part of the alicyclic structure formed ring members 3 to 20 together with the carbon atom to which R ^U and R ^V are combined they are bound to each other or it is, or is part of R ^U and R ^W aliphatic heterocyclic structure consisting ring members 5 to 20 together with the oxygen atom is bonded carbon atoms and R ^W that keyed R ^U, bonded to each other. )   The radiation-sensitive resin composition according to any one of claims 1 to 4, wherein the polymer component further has a structural unit other than the first structural unit and the second structural unit.   The ratio of the weight average molecular weight in terms of polystyrene as determined by gel permeation chromatography to the number average molecular weight in terms of polystyrene determined by gel permeation chromatography of the polymer component is 1.4 or more. 3. The radiation-sensitive resin composition according to item 1. Applying a radiation-sensitive resin composition according to any one of claims 1 to 6 directly or indirectly to a substrate;
Exposing the resist film formed by the coating step,
Developing the exposed resist film. In the same or different polymer, a polymer composition containing a polymer component having a first structural unit containing a phenolic hydroxyl group and a second structural unit containing an acid-dissociable group, wherein the polymer component is A polymer composition satisfying the formula (A).

(In the formula (A), X1 is the X1 by the retention time when the cumulative area with respect to the total area of the gel permeation chromatography (GPC) elution curve of the polymer component detected by the differential refractometer becomes 1%. X2 is the value (mol%) of the content ratio of the first structural unit to all the structural units constituting the polymer component contained in the eluted fraction, and X2 is the value of the ratio of the first structural unit to all the structural units constituting the polymer component. It is the value (mol%) of the content ratio of one structural unit.) In the same or different polymer, a polymer composition containing a polymer component having a first structural unit containing a phenolic hydroxyl group and a second structural unit containing an acid-dissociable group, wherein the polymer component is A polymer composition satisfying the formula (B).

(In the formula (B), X1 was eluted by a retention time at which the cumulative area of the polymer component detected by a differential refractometer with respect to the total area of a gel permeation chromatography (GPC) elution curve was 1%. X2 is the content ratio (mol%) of the first structural unit to all structural units constituting the polymer component contained in the fraction, and X2 is the first structural unit to all structural units constituting the polymer component. Is the value of the content ratio (mol%).)

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