JP6318937B2 - Radiation-sensitive resin composition and resist pattern forming method - Google Patents

Description

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

  The radiation-sensitive resin composition used in the manufacture of various electronic devices such as semiconductor devices and liquid crystal devices is used to irradiate acid from the acid generator in the exposed area by exposure to far ultraviolet rays such as ArF excimer laser light and exposure light such as electron beams. The acid is used as a catalyst to change the dissolution rate of the exposed portion and the unexposed portion with respect to the developer, thereby forming a resist pattern on the substrate.

  Such a radiation-sensitive resin composition is required to be able to form a resist pattern with high resolution, excellent cross-sectional rectangularity, and few defects such as bridge defects. In response to these requirements, various studies have been made on the structure and production method of the polymer contained in the radiation-sensitive resin composition. As such a polymer, for example, a polymer having a structural unit containing an acid dissociable group, a structural unit containing a lactone structure such as a γ-butyrolactone structure, or a structural unit containing a polar group such as a hydroxy group is used. (Japanese Patent Laid-Open No. 2003-5375 and Japanese Patent Laid-Open No. 2008-83370). In such a polymer, these structural units may be distributed unevenly, which is considered to be one of the causes for causing a resist pattern defect. As a method for removing such a polymer and improving the bridge defect suppression property of the radiation-sensitive resin composition, a method of purifying the polymer using a resin having a solubility parameter and a specific surface area within a specific range is examined. (See JP 2007-19351 A). According to this method, it is said that the occurrence of bridge defects can be suppressed to some extent. However, in recent years when miniaturization of resist patterns has progressed to a level of 50 nm or less, the demand for suppression of bridge defects has further increased, and the above-described conventional method cannot satisfy the demand. .

JP 2003-5375 A JP 2008-83370 A JP 2007-19351 A

  This invention is made | formed based on the above situations, The objective is to provide the radiation sensitive resin composition which is excellent in defect inhibitory property.

（式（Ａ）中、Ｘ１は、上記重合体の示差屈折計で検出されるゲルパーミエーションクロマトグラフィー溶出曲線において、高分子量側からの累積エリア面積が全エリア面積に対してａ％以上ｂ％以下（ａは、０以上５未満の任意の値である。ｂは、５を超え１５未満の任意の値である。）となる部分の重合体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、高分子量側からの累積エリア面積が全エリア面積に対してｃ％以上ｄ％以下（ｃは、１５を超え５０未満の任意の値である。ｄは、５０を超え８５以下の任意の値である。）となる部分の重合体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 in order to solve the above-described problems is directed to a first structural unit containing a lactone ring group (hereinafter also referred to as “structural unit (I)”) and a second structural unit containing an acid dissociable group (hereinafter referred to as “structure”). Unit (II) ”) (hereinafter also referred to as“ [A] polymer ”), and a radiation-sensitive acid generator (hereinafter also referred to as“ [B] acid generator ”). It is a radiation sensitive resin composition, Comprising: The said [A] polymer satisfy | fills a following formula, It is a radiation sensitive resin composition characterized by the above-mentioned.

(In the formula (A), X1 is a gel permeation chromatography elution curve detected with a differential refractometer of the above polymer, and the cumulative area area from the high molecular weight side is a% or more and b% with respect to the total area area. (A is an arbitrary value of 0 or more and less than 5; b is an arbitrary value of more than 5 and less than 15) of the first structural unit relative to all the structural units constituting the polymer of the portion X2 is a cumulative area area from the high molecular weight side to c% or more and d% or less with respect to the total area area (c is an arbitrary value of more than 15 and less than 50) D is an arbitrary value exceeding 50 and not more than 85.) The value (mol%) of the content ratio of the first structural unit with respect to all the structural units constituting the polymer of the portion.

  Another invention made in order to solve the above-mentioned problems comprises a step of forming a resist film, a step of exposing the resist film, and a step of developing the exposed resist film, It is the resist pattern formation method formed with a conductive resin composition.

  Yet another invention made to solve the above problems is a polymer having a first structural unit containing a lactone ring group and a second structural unit containing an acid dissociable group, and satisfying the above formula (A). is there.

Here, the “hydrocarbon group” includes a chain hydrocarbon group, an alicyclic hydrocarbon group, and an aromatic hydrocarbon group. The “hydrocarbon group” may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. The “chain hydrocarbon group” refers to a hydrocarbon group that does not include a cyclic structure but includes only a chain structure, and includes both a linear hydrocarbon group and a branched hydrocarbon group. The term “alicyclic hydrocarbon group” refers to a hydrocarbon group that includes only an alicyclic structure as a ring structure and does not include an aromatic ring structure, and includes a monocyclic alicyclic hydrocarbon group and a polycyclic alicyclic group. Includes both hydrocarbon groups. However, it is not necessary to be composed only of the 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 only of an aromatic ring structure, and a part thereof may include a chain structure or an alicyclic structure.
The “organic group” refers to a group containing at least one carbon atom.

  According to the radiation sensitive resin composition and the resist pattern forming method of the present invention, a resist pattern with few defects can be formed. The polymer of this invention can be used suitably as a polymer component of the said radiation sensitive resin composition. Therefore, these can be suitably used for manufacturing processes of semiconductor devices that are expected to be further miniaturized in the future.

It is a figure explaining the method of calculating the ratio of the content rate of a 1st structural unit from a gel permeation chromatography elution curve. It is a figure explaining each fraction obtained by preparative GPC of a polymer in an example. It is a ¹³ C-NMR measurement chart of a polymer (A-1) in an example.

<Radiation sensitive resin composition>
The radiation-sensitive resin composition contains a [A] polymer and a [B] acid generator. The radiation-sensitive resin composition includes a [C] acid diffusion controller, a polymer having a higher fluorine atom content than the [D] [A] polymer (hereinafter referred to as “[D] polymer”). And [E] a solvent may be contained, and other optional components may be contained as long as the effects of the present invention are not impaired.
Hereinafter, each component will be described.

[[A] polymer]
[A] The polymer is a polymer having the structural unit (I) and the structural unit (II), and satisfies the following formula (A).

  In the formula (A), X1 is a gel permeation chromatography elution curve detected by a differential refractometer of the polymer, and the cumulative area area from the high molecular weight side is a% or more and b% with respect to the total area area. (A is an arbitrary value of 0 or more and less than 5; b is an arbitrary value of more than 5 and less than 15) of the first structural unit relative to all the structural units constituting the polymer of the portion It is a value (mol%) of the content ratio. X2 is a cumulative area area from the high molecular weight side of c% or more and d% or less with respect to the total area area (c is an arbitrary value of more than 15 and less than 50. d is an arbitrary value of more than 50 and less than 85 Is the value (mol%) of the content ratio of the first structural unit with respect to all the structural units constituting the polymer of the portion.

  The said radiation sensitive resin composition is excellent in defect suppression property, when a [A] polymer has structural unit (I) and structural unit (II), and satisfy | fills the said Formula (A). The reason why the radiation-sensitive resin composition has the above-described configuration and thus exhibits the above-mentioned effects is not necessarily clear, but can be inferred as follows, for example. That is, the [A] polymer has a structural unit containing a lactone ring group on the high molecular weight side as compared with a normal polymer satisfying the above formula (A) and having the structural unit (I) and the structural unit (II). Have more. On the high molecular weight side of the polymer, the solubility is generally lowered, but the [A] polymer has more lactone ring groups so that the solubility of the polymer is maintained. It is considered that the occurrence of bridge defects derived from the undissolved residue of the composition is suppressed.

[A] The polymer contains, in addition to the structural unit (I) and the structural unit (II), a structural unit (III) containing at least one selected from the group consisting of a carbonate ring group and a sultone ring group described later, and a polarity. It may have a structural unit (IV) containing a group, and may have other structural units other than the structural units (I) to (IV). [A] The polymer may have one or more of each structural unit.
Hereinafter, each structural unit will be described.

[Structural unit (I)]
The structural unit (I) is a structural unit containing a lactone ring group. [A] Since the polymer has the structural unit (I), the radiation-sensitive resin composition containing the [A] polymer can adjust the solubility of the resist film in the developer, Adhesion between the pattern and the substrate can be improved. A lactone ring group refers to a group formed by removing one or more hydrogen atoms from a monocyclic or polycyclic ring containing one ring (lactone ring) containing a group represented by —O—C (O) —. In addition, this lactone ring is counted as the first ring, and when it has only a lactone ring, it is called a monocyclic lactone ring group, and when it has another ring, it is called a polycyclic lactone ring group regardless of its structure.

Examples of the lactone ring group include:
Monocyclic lactone ring groups such as butyrolactone ring groups and valerolactone ring groups;
And polycyclic lactone ring groups such as norbornane lactone ring group and 5-oxo-4-oxatricyclo [4.3.1.1 ^3,8 ] undecane ring group.

  As the lactone ring group, those having a larger ring-opening reaction rate with an alkali than the unsubstituted norbornane lactone ring group are preferable. Here, the “rate of ring-opening reaction of lactone ring group by alkali” refers to the rate of ring-opening reaction of lactone ring group in an aqueous solution at pH 10.

The lactone ring group includes a monocyclic lactone ring group, a polycyclic lactone ring group substituted with an electron withdrawing group, and a polycyclic lactone containing an oxygen atom or a sulfur atom in a ring other than the lactone ring. A cyclic group is preferred. Such a lactone ring group usually has a higher rate of ring-opening reaction with alkali than an unsubstituted norbornane lactone ring group.
Examples of the electron withdrawing group for substituting the lactone ring group include halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom, and fluorinated hydrocarbon groups such as cyano group and fluorinated alkyl group. . Among these, a fluorine atom, a cyano group, and a fluorinated alkyl group are preferable, and a fluorine atom, a cyano group, a trifluoromethyl group, and a hexafluoroisopropyl group are preferable.

  The structural unit (I) is not particularly limited as long as it contains a lactone ring group. For example, a structural unit containing a monocyclic lactone ring group (hereinafter also referred to as “structural unit (I-1)”), polycyclic And a structural unit containing a lactone ring group (hereinafter also referred to as “structural unit (I-2)”).

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

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

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

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

  Among these, the structural unit (I), the structural unit (II) in which the lactone ring group is substituted with an electron withdrawing group, and the structural unit (II) containing an oxygen atom or a sulfur atom in a ring other than the lactone ring Preferably, a structural unit derived from γ-butyrolactone-yl (meth) acrylate, a structural unit derived from 1- (γ-butyrolactone-yl) cyclohexane-1-yl (meth) acrylate, and norbornanelactone-yl (meth) acrylate More preferred are structural units derived from, structural units derived from 5-cyanonorbornanelactone-yl (meth) acrylate, and structural units derived from 7-oxanorbornanelactone-yl (meth) acrylate, and 5-cyanonorbornanelactone-yl ( Structural unit derived from (meth) acrylate, 7-oxanorbornanelactone-yl ( More preferred are structural units derived from (meth) acrylates.

  As a content rate of the said structural unit (I), 10 mol%-90 mol% are preferable with respect to all the structural units in a [A] polymer, 20 mol%-80 mol% are more preferable, 30 mol%-75 mol The mol% is more preferable, and 50 mol% to 70 mol% is particularly preferable. By making the content rate of structural unit (I) into the said range, the solubility to the developing solution of a resist film can be adjusted more appropriately, and the adhesiveness of a resist pattern and a board | substrate can be improved more.

[Structural unit (II)]
The structural unit (II) is a structural unit containing an acid dissociable group. The “acid-dissociable group” refers to a group that replaces a hydrogen atom of a carboxy group, a hydroxy group, or a sulfo group, and dissociates by the action of an acid. [A] Since the polymer has the structural unit (II), the radiation-sensitive resin composition has a difference in solubility in the developer between the exposed part and the unexposed part due to the acid generated by the exposure. A resist pattern can be formed.

  Examples of the structural unit (II) include a structural unit represented by the following formula (1) (hereinafter also referred to as “structural unit (II-1)”).

In said formula (1), R < ¹ > is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. Y ¹ is a monovalent acid dissociable group.

R ¹ is preferably a hydrogen atom or a methyl group, and more preferably a methyl group, from the viewpoint of copolymerization of the monomer that gives the structural unit (II-1).

The monovalent acid-dissociable group represented by Y ^1, preferably a group represented by the following formula (Y-1).

In the above formula (Y-1), R ^e1 is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ^e2 and R ^e3 are each independently a monovalent chain hydrocarbon group having 1 to 20 carbon atoms or a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, or these groups are An alicyclic structure having 3 to 20 ring members composed of carbon atoms bonded to each other and bonded thereto is represented.

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

Examples of the monovalent chain hydrocarbon group having 1 to 20 carbon atoms represented by R ^e1 , R ^e2 and R ^e3 include, for example,
Alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl and n-pentyl;
Alkenyl groups such as ethenyl group, propenyl group, butenyl group, pentenyl group;
Examples include alkynyl groups such as ethynyl group, propynyl group, butynyl group, and pentynyl group.
Among these, an alkyl group is preferable, an alkyl group having 1 to 4 carbon atoms is preferable, a methyl group, an ethyl group, and an i-propyl group are more preferable, and an ethyl group is particularly preferable.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms represented by R ^e1 , R ^e2 and R ^e3 include, for example,
A monocyclic cycloalkyl group such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cyclooctyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, a tetracyclododecyl group;
A monocyclic cycloalkenyl group such as a cyclopropenyl group, a cyclobutenyl group, a cyclopentenyl group, a cyclohexenyl group;
And polycyclic cycloalkenyl groups such as a norbornenyl group and a tricyclodecenyl group.
Among these, a monocyclic cycloalkyl group and a polycyclic cycloalkyl group are preferable, and a cyclopentyl group, a cyclohexyl group, a norbornyl group, and an adamantyl group are more preferable.

Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms represented by R ^e1 include:
Aryl groups such as phenyl, tolyl, xylyl, mesityl, naphthyl, methylnaphthyl, anthryl, methylanthryl;
Examples include aralkyl groups such as benzyl group, phenethyl group, naphthylmethyl group, and anthrylmethyl group.

Examples of the alicyclic structure having 3 to 20 ring members constituted and represented together with the carbon atom to which these groups are combined with each other are, for example,
Monocyclic cycloalkane structures such as cyclopropane structure, cyclobutane structure, cyclopentane structure, cyclohexane structure, cyclooctane structure;
Polycyclic cycloalkane structures such as norbornane structure, adamantane structure, tricyclodecane structure and tetracyclododecane structure;
Monocyclic cycloalkene structures such as cyclopropene structure, cyclobutene structure, cyclopentene structure, cyclohexene structure, cyclooctene structure;
Examples thereof include polycyclic cycloalkene structures such as a norbornene structure, a tricyclodecene structure, and a tetracyclododecene structure.
Among these, a monocyclic cycloalkane structure and a polycyclic cycloalkane structure are preferable, a monocyclic cycloalkane structure having 5 to 8 carbon atoms, and a polycyclic cycloalkane structure having 7 to 12 carbon atoms are more preferable, A cyclopentane structure, a cyclohexane structure, a cyclooctane structure, a norbornane structure, and an adamantane structure are more preferable, and a cyclopentane structure and an adamantane structure are particularly preferable.

  Examples of the structural unit (II-1) include structural units represented by the following formulas (1-1) to (1-8).

In the formulas (1-1) to (1-8), R ¹ has the same meaning as the formula (1). R ^e1 , R ^e2 and R ^e3 have the same ^{meaning as} in the above formula (Y-1). Each r is independently an integer of 1 to 3.

As the structural unit (II-1), structural units represented by the above formulas (1-2), (1-3), (1-5) and (1-6) are preferable. ) Is more preferable, the structural unit represented by the above formula (1-3) in which r is 1 is more preferable, and the above formula (1-3) in which r is 1 and R ^e1 is a methyl group. ) Is particularly preferred.

  As a content rate of structural unit (II), 10 mol%-90 mol% are preferable with respect to all the structural units which comprise a [A] polymer, 20 mol%-80 mol% are more preferable, 25 mol% -65 mol% is further more preferable, and 30 mol%-50 mol% is especially preferable. By making the content rate of structural unit (II) into the said range, the pattern formation property of a radiation sensitive resin composition can be improved more.

[Structural unit (III)]
The structural unit (III) is a structural unit containing at least one selected from the group consisting of a carbonate ring group and a sultone ring group. The said radiation sensitive resin composition can improve the adhesiveness to the board | substrate of the resist pattern formed because a [A] polymer further has structural unit (III).

  Examples of the structural unit containing the carbonate ring group include a structural unit represented by the following formula.

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

  Examples of the structural unit containing the sultone ring group include a structural unit represented by the following formula.

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

  As a content rate of structural unit (III), 0 mol%-70 mol% are preferable with respect to all the structural units which comprise a [A] polymer, 0 mol%-65 mol% are more preferable, 35 mol% -60 mol% is more preferable. By making the said content rate into the said range, the adhesiveness to the board | substrate of the resist pattern formed from the said radiation sensitive resin composition can be improved more.

[Structural unit (IV)]
The structural unit (IV) is a structural unit containing a polar group. The said radiation sensitive resin composition can improve the adhesiveness to the board | substrate of the resist pattern formed because a [A] polymer further has structural unit (IV). Examples of the polar group include a hydroxy group, a carboxy group, a cyano group, a nitro group, and a sulfonamide group. Among these, a hydroxy group and a carboxy group are preferable, and a hydroxy group is more preferable.

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

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

  As a content rate of structural unit (IV), 0 mol%-50 mol% are preferable with respect to all the structural units which comprise a [A] polymer, and 0 mol%-40 mol% are more preferable. By making the said content rate into the said range, the said radiation sensitive resin composition can improve the adhesiveness to the board | substrate of the resist pattern formed more.

[Other structural units]
[A] The polymer may have other structural units other than the structural units (I) to (IV). Examples of other structural units include structural units containing a non-dissociable alicyclic hydrocarbon group. As a content rate of another structural unit, 20 mol% or less is preferable with respect to all the structural units which comprise a [A] polymer, and 10 mol% or less is more preferable.

[[A] Distribution of structural unit (I) in polymer]
[A] The polymer satisfies the following formula (A).

  In the formula (A), X1 is a gel permeation chromatography elution curve detected by a differential refractometer of the polymer, and the cumulative area area from the high molecular weight side is a% or more and b% with respect to the total area area. (A is an arbitrary value of 0 or more and less than 5; b is an arbitrary value of more than 5 and less than 15) of the first structural unit relative to all the structural units constituting the polymer of the portion It is a value (mol%) of the content ratio. X2 is a cumulative area area from the high molecular weight side of c% or more and d% or less with respect to the total area area (c is an arbitrary value of more than 15 and less than 50. d is an arbitrary value of more than 50 and less than 85 Is the value (mol%) of the content ratio of the first structural unit with respect to all the structural units constituting the polymer of the portion.

  That is, in the [A] polymer, the value of the ratio (A) represented by the left side of the formula (A) is not less than the specific value.

The value of the ratio (A) can be obtained as follows.
(1) [A] The polymer is divided into a plurality of fractions having different molecular weights by preparative gel permeation chromatography (preparative GPC).
(2) Of the plurality of fractions obtained above, in the GPC elution curve (see FIG. 1), the portion (P) that is a% or more and b% or less with respect to the total area area of the cumulative area area from the high molecular weight side And a portion (Q) that is c% or more and d% or less.
(3) The content ratio of the structural unit (I) of each [A] polymer in the part (P) and the part (Q) is determined by NMR measurement.
(4) The ratio (A) is calculated by the above formula (A) from the value of the content ratio of the structural unit (I) of each [A] polymer in the part (P) and the part (Q) obtained above.

The a is 0 or more and less than 5, preferably 0 or more and 3 or less, more preferably 0 or more and 2 or less, further preferably 0 or more and 1 or less, and particularly preferably 0.
The above b is more than 5 and less than 15, preferably 7 or more and 13 or less, more preferably 8 or more and 12 or less, further preferably 9 or more and 11 or less, and particularly preferably 10.
The c is more than 15 and less than 50, preferably 17 or more and 40 or less, more preferably 18 or more and 30 or less, still more preferably 19 or more and 25 or less, and particularly preferably 20.
The d is more than 50 and 85 or less, preferably 55 or more and 75 or less, more preferably 57 or more and 70 or less, further preferably 58 or more and 65 or less, and particularly preferably 60.

  In addition to the method described above, the ratio (A) can be obtained, for example, by dividing the [A] polymer into a number of fractions, and determining the content of the structural unit (I) of the [A] polymer in each fraction. After obtaining by NMR measurement, a method of calculating the values of X1 and X2 in the above formula (A) from these values may be used.

  The lower limit of the ratio (A) is 0.03, 0.05 is preferable, 0.07 is more preferable, 0.09 is further preferable, 0.10 is particularly preferable, and 0.11 is more particularly preferable. 0.12 is more particularly preferable, and 0.13 is most preferable. The upper limit of the ratio (B) is preferably 0.3, more preferably 0.25, still more preferably 0.20, and particularly preferably 0.18.

  [A] The weight average molecular weight (Mw) in terms of polystyrene by GPC (Gel Permeation Chromatography) of the polymer is preferably 1,000 to 50,000, more preferably 2,000 to 30,000, and more preferably 3,000 to 20 Is more preferable, and 4,000 to 10,000 is particularly preferable. [A] When the Mw of the polymer is less than the lower limit, the heat resistance of the resist film may be lowered. [A] If the Mw of the polymer exceeds the above upper limit, the developability of the radiation-sensitive resin composition may deteriorate.

  [A] The ratio (Mw / Mn, dispersity) of Mw to the number average molecular weight (Mn) in terms of polystyrene by GPC of the polymer is preferably 1 to 5, more preferably 1 to 3, and 1 to 2.5. More preferably, 1-2 is especially preferable.

  [A] The content of the polymer is preferably 70% by mass or more, more preferably 80% by mass or more, and still more preferably 85% by mass or more based on the total solid content in the radiation-sensitive resin composition.

[[A] Polymer Synthesis Method]
[A] The polymer can be synthesized according to a conventional method such as radical polymerization. For example, (1) a method in which a solution containing a monomer and a radical initiator is dropped into a reaction solvent or a solution containing a monomer to cause a polymerization reaction, (2) a solution containing the monomer and a radical initiator A method of dropping a solution containing a monomer separately into a reaction solvent or a solution containing a monomer to cause a polymerization reaction, (3) a plurality of types of solutions containing each monomer and a solution containing a radical initiator And (4) a method of polymerizing a solution containing a monomer and a radical initiator in the absence of a solvent or in a reaction solvent, etc. Can be synthesized.

  [A] The polymer has more structural units (I) containing a lactone ring group on the high molecular weight side. The method for obtaining such a polymer is not particularly limited. For example, at the initial stage of the polymerization reaction (A), the concentration of the monomer that gives the structural unit (I) is higher than the concentration of other monomers. (B) a method of adjusting the addition amount or addition rate of each monomer, and (B) when the polymerization rate of the monomer giving the structural unit (I) is higher than that of other monomers, the polymerization reaction is lower A method of starting with temperature and gradually increasing the temperature can be applied. Each addition amount and each addition rate of each monomer, and the polymerization reaction temperature may be appropriately selected according to the type of radical polymerization initiator, the type of monomer, and the desired value (X1-X2) / X2. it can.

  In addition, when making a monomer solution drop and react with respect to a monomer solution, as monomer amount in the dropped monomer solution, it is 30 with respect to the monomer total amount used for superposition | polymerization. It is preferably at least mol%, more preferably at least 50 mol%, still more preferably at least 70 mol%.

  What is necessary is just to determine the reaction temperature in these methods suitably with initiator seed | species. Usually, it is 30 degreeC-150 degreeC, 40 degreeC-150 degreeC is preferable, and 50 degreeC-140 degreeC is more preferable. Although dripping time changes with conditions, such as reaction temperature, the kind of initiator, and the monomer made to react, it is 30 minutes-8 hours normally, 45 minutes-6 hours are preferable, and 1 hour-5 hours are more preferable. Also, the total reaction time including the dropping time varies depending on the conditions as in the dropping time, but is usually 30 minutes to 12 hours, preferably 45 minutes to 12 hours, and more preferably 1 to 10 hours.

  Examples of the radical initiator used in the polymerization include azobisisobutyronitrile (AIBN), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), and 2,2′-azobis. (2-cyclopropylpropionitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2'-azobis (2-methylpropionate), dimethyl 2,2'-azobis Examples thereof include azo radical initiators such as isobutyrate; peroxide radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, and the like. Of these, AIBN and dimethyl 2,2'-azobis (2-methylpropionate) are preferred. In addition, 1 type (s) or 2 or more types may be used for a radical initiator.

  As a reaction solvent, any solvent other than a solvent that inhibits polymerization (nitrobenzene having a polymerization inhibiting effect, mercapto compound having a chain transfer effect, etc.) and capable of dissolving the monomer may be used. it can. Examples thereof include alcohols, ethers, ketones, amides, esters / lactones, nitriles, and mixed solvents thereof. One or two or more of these solvents may be used.

  The polymer obtained by the polymerization reaction is preferably recovered by a reprecipitation method. That is, after the polymerization reaction is completed, the polymer is recovered as a powder by introducing the polymerization solution into a reprecipitation solvent. As the reprecipitation solvent, alcohols or alkanes may be used alone or in combination of two or more. In addition to the reprecipitation method, the polymer can also be recovered by removing low molecular parts such as monomers and oligomers by a liquid separation operation, a column operation, an ultrafiltration operation, or the like.

<[B] Acid generator>
[B] The acid generator is a substance that generates an acid upon exposure. The generated acid dissociates the acid-dissociable group or the like of the structural unit (II) of the polymer [A] to produce an oxo acid group and / or a phenolic hydroxyl group, and dissolves these polymers in the developer. As the inclusion form of the [B] acid generator in the radiation-sensitive resin composition, a resist pattern can be formed from the radiation-sensitive resin composition. It may be in the form of a compound (hereinafter also referred to as “[B] acid generator” as appropriate), a form incorporated as part of a polymer, or both forms.

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

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

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

  [B] The acid generator is preferably a compound represented by the following formula (2). [B] Since the acid generator has the following structure, the diffusion length of the acid generated by exposure in the resist film is appropriately shortened due to the interaction with the polar structure of the [A] polymer and the like. As a result, the LWR performance and the like of the radiation sensitive resin composition can be further improved.

In the above formula (2), R ² is a monovalent group containing an alicyclic structure having 6 or more ring members or a monovalent group containing an aliphatic heterocyclic structure having 6 or more ring members. R ³ is a fluorinated alkanediyl group having 1 to 10 carbon atoms. G ⁺ is a monovalent radiolytic onium cation.

The “number of ring members” in R ² refers to the number of atoms constituting the ring of the alicyclic structure and the aliphatic heterocyclic structure, and in the case of the polycyclic alicyclic structure and the polycyclic aliphatic heterocyclic structure, The number of atoms that make up the ring.

Examples of the monovalent group containing an alicyclic structure having 6 or more ring members represented by R ² include:
A monocyclic cycloalkyl group such as a cyclooctyl group, a cyclononyl group, a cyclodecyl group, a cyclododecyl group;
A monocyclic cycloalkenyl group such as a cyclooctenyl group and a cyclodecenyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, a tetracyclododecyl group;
And polycyclic cycloalkenyl groups such as a norbornenyl group and a tricyclodecenyl group.

Examples of the monovalent group containing an aliphatic heterocyclic structure having 6 or more ring members represented by R ² include:
A group containing a lactone structure such as a norbornanelactone-yl group;
A group containing a sultone structure such as a norbornane sultone-yl group;
An oxygen atom-containing heterocyclic group such as an oxacycloheptyl group and an oxanorbornyl group;
A nitrogen atom-containing heterocyclic group such as an azacyclohexyl group, an azacycloheptyl group, a diazabicyclooctane-yl group;
And sulfur atom-containing heterocyclic groups such as a thiacycloheptyl group and a thianorbornyl group.

The number of ring members of the group represented by R ² is preferably 8 or more, more preferably 9 to 15 and even more preferably 10 to 13 from the viewpoint that the diffusion length of the acid described above becomes more appropriate.

Among these, R ² is preferably a monovalent group containing an alicyclic structure having 9 or more ring members, or a monovalent group containing an aliphatic heterocyclic structure having 9 or more ring members, an adamantyl group, a hydroxyadamantyl group , A norbornanelactone-yl group, and a 5-oxo-4-oxatricyclo [4.3.1.1 ^3,8 ] undecan-yl group are more preferable, and an adamantyl group is more preferable.

Examples of the fluorinated alkanediyl group having 1 to 10 carbon atoms represented by R ³ include one of hydrogen atoms of an alkanediyl group having 1 to 10 carbon atoms such as a methanediyl group, an ethanediyl group, and a propanediyl group. Examples include groups in which the above is substituted with a fluorine atom.
Among these, SO ₃ ^- fluorinated alkane diyl group which has a fluorine atom to carbon atom is bonded to adjacent groups are preferred, SO ₃ ^- 2 fluorine atoms to the carbon atom adjacent to the group is attached More preferred are fluorinated alkanediyl groups, 1,1-difluoromethanediyl group, 1,1-difluoroethanediyl group, 1,1,3,3,3-pentafluoro-1,2-propanediyl group, 1,1 1,2,2-tetrafluoroethanediyl group, 1,1,2,2-tetrafluorobutanediyl group, and 1,1,2,2-tetrafluorohexanediyl group are more preferable.

The monovalent radiation-decomposable onium cation represented by G ⁺ is a cation that is decomposed by exposure light exposure. In the exposed portion, sulfonic acid is generated from protons generated by the decomposition of the radiolytic onium cation and the sulfonate anion. Examples of the monovalent radiolytic onium cation represented by X ⁺ include elements such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, and Bi. And radiation-decomposable onium cations. Examples of the cation containing S (sulfur) as an element include a sulfonium cation and a tetrahydrothiophenium cation. Examples of the cation containing I (iodine) as an element include an iodonium cation. Among these, a sulfonium cation represented by the following formula (G-1), a tetrahydrothiophenium cation represented by the following formula (G-2), and an iodonium cation represented by the following formula (G-3) preferable.

In the above formula (G-1), R ^a1 , R ^a2 and R ^a3 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, substituted or unsubstituted. aromatic hydrocarbon group having 6 to 12 carbon atoms, a or a -OSO ₂ -R ^P or _-SO 2 -R ^Q, or two or more are combined with each other configured ring of these groups . R ^P and R ^Q are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms. Or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k1, k2 and k3 are each independently an integer of 0 to 5. R ^a1 to R ^a3 and when ^{R P} and ^{R Q} are a plurality each of the plurality of ^R a1 ^{to R a3} and ^{R P} and ^{R Q} may be the same as or different from each other.
In the above formula (G-2), R ^b1 represents a substituted or unsubstituted linear or branched alkyl group having 1 to 8 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon having 6 to 8 carbon atoms. It is a group. k4 is an integer of 0-7. If R ^b1 is plural, the plurality of R ^b1 may be the same or different, and plural R ^b1 may represent a constructed ring aligned with each other. R ^b2 is a substituted or unsubstituted linear or branched alkyl group having 1 to 7 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 or 7 carbon atoms. k5 is an integer of 0-6. If R ^b2 is plural, the plurality of R ^b2 may be the same or different, and plural R ^b2 may represent a keyed configured ring structure. t is an integer of 0-3.
In the above formula (G-3), R ^c1 and R ^c2 each independently represent a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number of 6 12 aromatic hydrocarbon group, or an -OSO ₂ -R ^R or _-SO 2 -R ^S, or two or more are combined with each other configured ring of these groups. R ^R and R ^S are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, or a substituted or unsubstituted alicyclic hydrocarbon group having 5 to 25 carbon atoms. Or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms. k6 and k7 are each independently an integer of 0 to 5. R ^{c1, R} c2, ^R when ^R and ^{R S} is plural respective plurality of ^{R c1,} R c2, ^{R R} and ^{R S} may have respectively the same or different.

Examples of the unsubstituted linear alkyl group represented by R ^{a1 to} R ^a3 , R ^b1 , R ^b2 , R ^c1 and R ^c2 include a methyl group, an ethyl group, an n-propyl group, and n-butyl. Groups and the like.
Examples of the unsubstituted branched alkyl group represented by R ^{a1 to} R ^a3 , R ^b1 , R ^b2 , R ^c1 and R ^c2 include an i-propyl group, an i-butyl group, a sec-butyl group, Examples include t-butyl group.
Examples of the unsubstituted aromatic hydrocarbon group represented by R ^{a1 to} R ^a3 , R ^c1, and R ^c2 include aryl groups such as phenyl group, tolyl group, xylyl group, mesityl group, and naphthyl group; benzyl group And aralkyl groups such as a phenethyl group.
Examples of the unsubstituted aromatic hydrocarbon group represented by R ^b1 and R ^b2 include a phenyl group, a tolyl group, and a benzyl group.

Examples of the substituent that may substitute the hydrogen atom of the alkyl group and aromatic hydrocarbon 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, and a cyano group. Group, nitro group, alkoxy group, alkoxycarbonyl group, alkoxycarbonyloxy group, acyl group, acyloxy group and the like.
Among these, a halogen atom is preferable and a fluorine atom is more preferable.

R ^{a1 to} R ^a3 , R ^b1 , R ^b2 , R ^c1 and R ^c2 include an unsubstituted linear or branched alkyl group, a fluorinated alkyl group, and an unsubstituted monovalent aromatic hydrocarbon group. , —OSO ₂ —R ″ and —SO ₂ —R ″ are preferred, fluorinated alkyl groups, unsubstituted monovalent aromatic hydrocarbon groups are more preferred, and fluorinated alkyl groups are more preferred. R ″ is an unsubstituted monovalent alicyclic hydrocarbon group or an unsubstituted monovalent aromatic hydrocarbon group.

As k1, k2, and k3 in the formula (G-1), integers of 0 to 2 are preferable, 0 or 1 is more preferable, and 0 is more preferable.
As k4 in the said Formula (G-2), the integer of 0-2 is preferable, 0 or 1 is more preferable and 1 is further more preferable. k5 is preferably an integer of 0 to 2, more preferably 0 or 1, and still more preferably 0.
As k6 and k7 in the said Formula (G-3), the integer of 0-2 is preferable, 0 or 1 is more preferable, and 0 is further more preferable.

  Examples of the acid generator represented by the above formula (2) include compounds represented by the following formulas (2-1) to (2-13) (hereinafter referred to as “compounds (2-1) to (2-13)”. ) ")) And the like.

In the formulas (2-1) to (2-13), G ⁺ has the same meaning as the formula (2).

  [B] Of these, the acid generator is preferably an onium salt compound, more preferably a sulfonium salt, a sulfonium salt having an anion containing an adamantane structure, a sulfonium salt having an anion containing a norbornane sultone structure, or a sulfonamide structure Is more preferable, and a compound (2-4) is especially preferable.

  In addition, as the [B] acid generator, a polymer in which the structure of the above formula (2) such as a polymer having a structural unit represented by the following formula (2-14) is incorporated as a part of the polymer is also included. preferable.

In said formula (2-14), R 'is a hydrogen atom or a methyl group. G ⁺ is synonymous with the above formula (2).

  [B] As the content of the acid generator, when the [B] acid generator is a [B] acid generator, from the viewpoint of ensuring the sensitivity and developability of the radiation-sensitive resin composition, [A] 0.1 parts by mass or more and 40 parts by mass or less are preferable, 100 parts by mass or more and 30 parts by mass or less are more preferable, and 1 part by mass or more and 20 parts by mass or less are more preferable, and 3 parts by mass is preferable. 15 parts by mass or more is particularly preferable. [B] By making content of an acid generator into the said range, the sensitivity and developability of the said radiation sensitive resin composition improve more, and as a result, LWR performance etc. can be improved more. [B] 1 type (s) or 2 or more types can be used for an acid generator.

<[C] Acid diffusion controller>
The said radiation sensitive resin composition may contain a [C] acid diffusion control body as needed.
[C] The acid diffusion control body controls the diffusion phenomenon in the resist film of the acid generated from the [B] acid generator by exposure, has the effect of suppressing undesirable chemical reactions in the non-exposed areas, and the radiation sensitivity obtained The storage stability of the photosensitive resin composition is further improved, the resolution of the resist is further improved, and the change in the line width of the resist pattern due to fluctuations in the holding time from exposure to development processing can be suppressed, thereby stabilizing the process. A radiation-sensitive resin composition having excellent properties can be obtained. [C] The content of the acid diffusion controller in the radiation-sensitive resin composition is incorporated as a part of the polymer even in the form of a free compound (hereinafter referred to as “[C] acid diffusion controller” as appropriate). Or both of these forms.

  [C] Examples of the acid diffusion controller include a compound represented by the following formula (3) (hereinafter also referred to as “nitrogen-containing compound (I)”), a compound having two nitrogen atoms in the same molecule (hereinafter referred to as “nitrogen-containing compound (I)”). , “Nitrogen-containing compound (II)”, compounds having three nitrogen atoms (hereinafter also referred to as “nitrogen-containing compound (III)”), amide group-containing compounds, urea compounds, nitrogen-containing heterocyclic compounds, etc. Can be mentioned.

In the above formula (3), R ⁴ , R ⁵ and R ⁶ are each independently a hydrogen atom, an optionally substituted linear, branched or cyclic alkyl group, an aryl group or an aralkyl group. .

  Examples of the nitrogen-containing compound (I) include monoalkylamines such as n-hexylamine; dialkylamines such as di-n-butylamine; trialkylamines such as triethylamine and tri-n-pentylamine; Aromatic amines etc. are mentioned.

  Examples of the nitrogen-containing compound (II) include ethylenediamine, N, N, N ′, N′-tetramethylethylenediamine, and the like.

  Examples of the nitrogen-containing compound (III) include polyamine compounds such as polyethyleneimine and polyallylamine; and polymers such as dimethylaminoethylacrylamide.

  Examples of the amide group-containing compound include formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methylpyrrolidone and the like. Can be mentioned.

  Examples of the urea compound include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, tributylthiourea and the like. .

  Examples of the nitrogen-containing heterocyclic compound include pyridines such as pyridine and 2-methylpyridine; morpholines such as N-propylmorpholine and N- (undecan-1-ylcarbonyloxyethyl) morpholine; pyrazine, pyrazole and the like. It is done.

  Moreover, the compound which has an acid dissociable group can also be used as said nitrogen-containing organic compound. Examples of the nitrogen-containing organic compound having such an acid dissociable group include Nt-butoxycarbonylpiperidine, Nt-butoxycarbonylimidazole, Nt-butoxycarbonylbenzimidazole, Nt-butoxycarbonyl- 2-phenylbenzimidazole, N- (t-butoxycarbonyl) di-n-octylamine, N- (t-butoxycarbonyl) diethanolamine, N- (t-butoxycarbonyl) dicyclohexylamine, N- (t-butoxycarbonyl) Examples thereof include diphenylamine, Nt-butoxycarbonyl-4-hydroxypiperidine, Nt-amyloxycarbonyl-4-hydroxypiperidine and the like.

  Further, as the [D] acid diffusion control agent, a photodisintegratable base that is exposed to light and generates a weak acid by exposure can also be used. Examples of the photodegradable base include an onium salt compound that decomposes upon exposure and loses acid diffusion controllability. Examples of the onium salt compound include a sulfonium salt compound represented by the following formula (4-1), an iodonium salt compound represented by the following formula (4-2), and the like.

In the above formulas (4-1) and (4-2), R ^{7 to} R ¹¹ are each independently a hydrogen atom, an alkyl group, an alkoxy group, a hydroxy group, or a halogen atom. E ^- and Q ^- are each ^{independently, OH -, R β -COO -} , R β -SO 3 -, R γ -N - Table with ^-SO ₂ O-R δ or the following formula (4-3) Anion. However, R ( ^beta) is an alkyl group, an aryl group, or an aralkyl group. R ^γ and R ^δ are each independently a monovalent organic group having 1 to 20 carbon atoms, or composed of —N ⁻ —SO ₂ O— in which these groups are combined with each other and bonded to each other. A ring structure having 4 to 20 carbon atoms is represented.

In the above formula (4-3), R ^12, a part or all of the hydrogen atoms linear or branched alkyl group having 1 to 12 carbon atoms which may be substituted by a fluorine atom, or carbon atoms 1 It is a -12 linear or branched alkoxyl group. u is an integer of 0-2.

  As said photodegradable base, the compound etc. which are represented by a following formula are mentioned, for example.

  Of these, the photodegradable base is preferably a sulfonium salt, more preferably a triarylsulfonium salt, and even more preferably triphenylsulfonium salicylate or triphenylsulfonium 10-camphorsulfonate.

  [C] The content of the acid diffusion controller is 0 to 20 parts by mass with respect to 100 parts by mass of the polymer [A] when the [C] acid diffusion controller is a [C] acid diffusion controller. Part, preferably 0.1 part by weight to 15 parts by weight, more preferably 0.5 part by weight to 10 parts by weight, and particularly preferably 1 part by weight to 7 parts by weight. [C] By setting the content of the acid diffusion controller within the above range, the resolution, storage stability, and the like of the radiation-sensitive resin composition can be improved. [C] When the content of the acid diffusion controller exceeds the upper limit, the sensitivity of the radiation-sensitive resin composition may be lowered.

<[D] Polymer>
[D] The polymer is a polymer having a higher fluorine atom content than the [A] polymer. When the radiation-sensitive resin composition contains a [D] polymer, when the resist film is formed, the distribution is unevenly distributed near the resist film surface due to the oil-repellent characteristics of the fluorine atom-containing polymer in the resist film. It is possible to prevent the acid generator, the acid diffusion controller and the like from being eluted into the immersion medium during immersion exposure. Further, due to the water-repellent characteristics of this fluorine atom-containing polymer, the advancing contact angle between the resist film and the immersion medium can be controlled within a desired range, and the occurrence of bubble defects can be suppressed. Furthermore, the receding contact angle between the resist film and the immersion medium is increased, and high-speed scanning exposure is possible without leaving water droplets. Thus, the said radiation sensitive resin composition can form the resist film suitable for an immersion exposure method by further containing a [D] polymer.

  The [D] polymer is not particularly limited as long as it is a polymer having a fluorine atom, but preferably has a structural unit containing a fluorine atom. Examples of the structural unit containing a fluorine atom include 1,1,1,3,3,3-hexafluoro-2-propyl (meth) acrylate and 1,1-difluoro-1-ethoxycarbonylbutan-2-yl. Examples include structural units derived from (meth) acrylates containing fluorine atoms such as (meth) acrylates. As a structural unit containing the said fluorine atom, an alkali dissociable group may be included, for example. An “alkali dissociable group” is a group that replaces a hydrogen atom such as a carboxy group or a hydroxy group, and is dissociated by the action of an alkali (for example, an aqueous 2.38 mass% tetramethylammonium hydroxide solution at 23 ° C.). Refers to the group.

  As a content rate of the structural unit containing the said fluorine atom, 10 mol%-80 mol% are preferable with respect to all the structural units which comprise a [D] polymer, 15 mol%-60 mol% are more preferable, 20 More preferably, mol% to 40 mol%. By making the said content rate into the said range, the uneven distribution of the [D] polymer to the above-mentioned resist film surface vicinity can be promoted more.

The [D] polymer preferably further has a structural unit containing an acid dissociable group. [D] When a polymer further has a structural unit containing an acid dissociable group, the undissolved residue of the [D] polymer after development can be further suppressed. Examples of the structural unit containing an acid dissociable group include the structural unit (II) in the above [A] polymer.
As a content rate of the structural unit containing the said acid dissociable group, 0 mol%-90 mol% are preferable with respect to all the structural units which comprise a [D] polymer, and 20 mol%-85 mol% are more preferable. 40 mol% to 80 mol% is more preferable.

  As content of the said [D] polymer, 0.1 mass part-20 mass parts are preferable with respect to 100 mass parts of [A] polymers, 0.5 mass part-15 mass parts are more preferable, 1 More preferred is 10 parts by mass.

<[E] solvent>
The radiation-sensitive resin composition usually contains an [E] solvent. [E] The solvent is not particularly limited as long as it is a solvent capable of dissolving or dispersing at least the [A] polymer, the [B] acid generator, and the optionally contained [C] acid diffusion controller.

  [E] Examples of the solvent include alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, hydrocarbon solvents, and the like.

As an alcohol solvent, for example,
C1-C18 aliphatic monoalcohol solvents such as 4-methyl-2-pentanol and n-hexanol;
An alicyclic monoalcohol solvent having 3 to 18 carbon atoms such as cyclohexanol;
A C2-C18 polyhydric alcohol solvent such as 1,2-propylene glycol;
Examples thereof include C3-C19 polyhydric alcohol partial ether solvents such as propylene glycol monomethyl ether.

As an ether solvent, for example,
Dialkyl ether solvents such as diethyl ether, dipropyl ether, dibutyl ether, dipentyl ether, diisoamyl ether, dihexyl ether, diheptyl ether;
Cyclic ether solvents such as tetrahydrofuran and tetrahydropyran;
Aromatic ring-containing ether solvents such as diphenyl ether and anisole (methylphenyl ether) are exemplified.

Examples of ketone solvents include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, 2-heptanone (methyl-n-pentyl ketone), and ethyl-n-butyl ketone. Chain ketone solvents such as methyl-n-hexyl ketone, di-iso-butyl ketone and trimethylnonanone:
Cyclic ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone and methylcyclohexanone:
2,4-pentanedione, acetonylacetone, acetophenone and the like can be mentioned.

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

Examples of ester solvents 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;
Polycarboxylic 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
an aliphatic hydrocarbon solvent 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.

  Among these, ester solvents and ketone solvents are preferable, polyhydric alcohol partial ether acetate solvents and cyclic ketone solvents are more preferable, and propylene glycol monomethyl ether acetate and cyclohexanone are further preferable. The radiation-sensitive resin composition may contain one or more [E] solvents.

<Other optional components>
In addition to the components [A] to [D], the radiation-sensitive resin composition includes, for example, an uneven distribution accelerator, a surfactant, an alicyclic skeleton-containing compound, a sensitizer, and the like as other optional components. May be contained. The said radiation sensitive resin composition may contain 1 type (s) or 2 or more types of other arbitrary components, respectively.

[Uneven distribution promoter]
The uneven distribution accelerator has an effect of segregating the [D] polymer on the resist film surface more efficiently when the radiation-sensitive resin composition contains the [D] polymer. By including this uneven distribution accelerator in the radiation sensitive resin composition, the amount of the [D] polymer added can be reduced as compared with the conventional case. Therefore, it is possible to further suppress the elution of components from the resist film to the immersion liquid without impairing the resolution, LWR performance, and defect suppression, or to perform immersion exposure at a higher speed by high-speed scanning. As a result, it is possible to improve the hydrophobicity of the resist film surface that suppresses immersion-derived defects such as watermark defects. Examples of such an uneven distribution promoter include low molecular compounds having a relative dielectric constant of 30 or more and 200 or less and a boiling point at 1 atm of 100 ° C. or more. Specific examples of such compounds include lactone compounds, carbonate compounds, nitrile compounds, and polyhydric alcohols.

Examples of the lactone compound include γ-butyrolactone, valerolactone, mevalonic lactone, and norbornane lactone.
Examples of the carbonate compound include propylene carbonate, ethylene carbonate, butylene carbonate, vinylene carbonate, and the like.
Examples of the nitrile compound include succinonitrile.
Examples of the polyhydric alcohol include glycerin.

  The content of the uneven distribution accelerator is preferably 10 parts by mass to 500 parts by mass, more preferably 15 parts by mass to 300 parts by mass with respect to 100 parts by mass of the total amount of the polymer in the radiation sensitive resin composition. 20 mass parts-250 mass parts are further more preferable, and 25 mass parts-200 mass parts are especially preferable.

[Surfactant]
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, polyethylene glycol diacrylate. Nonionic surfactants such as stearate; commercially available products include KP341 (Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (above, Kyoeisha Chemical Co., Ltd.), F-top EF301, EF303, EF352 (above, Tochem Products), MegaFuck F171, F173 (above, DIC), Florard FC430, FC431 (above, Sumitomo 3M) Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (above, Asahi Glass Industrial Co., Ltd.) Can be mentioned.
As content of the said surfactant, it is 2 mass parts or less normally with respect to 100 mass parts of [A] polymers.

[Alicyclic skeleton-containing compound]
The alicyclic skeleton-containing compound has an effect of improving dry etching resistance, pattern shape, adhesion to the substrate, and the like.

Examples of the alicyclic skeleton-containing compound include adamantane derivatives such as 1-adamantanecarboxylic acid, 2-adamantanone, and 1-adamantanecarboxylic acid t-butyl;
Deoxycholic acid esters such as t-butyl deoxycholate, t-butoxycarbonylmethyl deoxycholic acid, 2-ethoxyethyl deoxycholic acid;
Lithocholic acid esters such as t-butyl lithocholic acid, t-butoxycarbonylmethyl lithocholic acid, 2-ethoxyethyl lithocholic acid;
3- [2-Hydroxy-2,2-bis (trifluoromethyl) ethyl] tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodecane, 2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo [4.2.1.0 ^3,7 ] nonane, and the like.
As content of the said alicyclic skeleton containing compound, it is 5 mass parts or less normally with respect to 100 mass parts of [A] polymers.

[Sensitizer]
A sensitizer exhibits the effect | action which increases the production amount of the acid from [B] acid generator etc., and there exists an effect which improves the "apparent sensitivity" of the said radiation sensitive resin composition.

Examples of the sensitizer include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, phenothiazines and the like. These sensitizers may be used alone or in combination of two or more.
As content of the said sensitizer, it is 2 mass parts or less normally with respect to 100 mass parts of [A] polymers.

<Method for preparing radiation-sensitive resin composition>
The radiation sensitive resin composition includes, for example, [A] polymer, [B] acid generator, optional components such as [C] acid diffusion controller contained as necessary, and [E] solvent as predetermined. It can prepare by mixing in the ratio. The radiation-sensitive resin composition is preferably filtered after mixing with, for example, a filter having a pore size of about 0.2 μm. As solid content concentration of the said radiation sensitive resin composition, it is 0.1 mass%-50 mass% normally, 0.5 mass%-30 mass% are preferable, and 1 mass%-20 mass% are more preferable.

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

<Resist pattern formation method>
The resist pattern forming method is:
A step of forming a resist film (hereinafter also referred to as a “resist film forming step”),
A step of exposing the resist film (hereinafter also referred to as “exposure step”), and a step of developing the exposed resist film (hereinafter also referred to as “development step”).
The resist film is formed from the radiation-sensitive resin composition.

According to the resist pattern forming method, since the radiation sensitive resin composition described above is used, a resist pattern with few defects can be formed.
Hereinafter, each step will be described.

[Resist film forming step]
In this step, a resist film is formed using the radiation sensitive resin composition. Examples of the substrate on which the resist film is formed include conventionally known ones such as a silicon wafer, silicon dioxide, and a wafer coated with aluminum. Further, for example, an organic or inorganic antireflection film disclosed in Japanese Patent Publication No. 6-12452, Japanese Patent Application Laid-Open No. 59-93448, or the like may be formed on the substrate. Examples of the application method include spin coating (spin coating), cast coating, roll coating, and the like. After application, pre-baking (PB) may be performed as needed to volatilize the solvent in the coating film. As PB temperature, it is 60 to 140 degreeC normally, and 80 to 120 degreeC is preferable. The PB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds. The thickness of the resist film to be formed is preferably 10 nm to 1,000 nm, and more preferably 10 nm to 500 nm.

  In order to prevent the influence of basic impurities and the like contained in the environmental atmosphere, a protective film disclosed in, for example, JP-A-5-188598 can be provided on the resist film. Further, in order to prevent the acid generator and the like from flowing out of the resist film, a liquid immersion protective film disclosed in, for example, JP-A-2005-352384 can be provided on the resist film. These techniques can be used in combination.

[Exposure process]
In this step, exposure is performed by irradiating the resist film formed in the resist film forming step with exposure light through a photomask or the like. The exposure light may be, for example, electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, extreme ultraviolet light (13.5 nm, EUV), X-rays, γ-rays, electron beams, α-rays, depending on the line width of the target pattern. And charged particle beams. Among these, far ultraviolet rays, EUV, and electron beams are preferable, ArF excimer laser light (wavelength 193 nm), KrF excimer laser light (wavelength 248 nm), EUV, and electron beams are more preferable, and ArF excimer laser light, EUV, and electron beams are preferable. Further preferred.

  When exposure is performed by immersion exposure, examples of the immersion liquid to be used include water and a fluorine-based inert liquid. The immersion liquid is preferably a liquid that is transparent to the exposure wavelength and has a refractive index temperature coefficient that is as small as possible so as to minimize distortion of the optical image projected onto the film. In the case of excimer laser light (wavelength 193 nm), it is preferable to use water from the viewpoints of availability and easy handling in addition to the above-described viewpoints. When water is used, an additive that reduces the surface tension of water and increases the surface activity may be added in a small proportion. This additive is preferably one that does not dissolve the resist film on the wafer and can ignore the influence on the optical coating on the lower surface of the lens. The water used is preferably distilled water.

  After the exposure, post-exposure baking (PEB) is performed, and in the exposed part of the resist film, the acid-dissociable group of the [A] polymer and the like by the acid generated from the [B] acid generator by the exposure Is preferably promoted. This PEB causes a difference in solubility in the developer between the exposed area and the unexposed area. As PEB temperature, it is 50 to 180 degreeC normally, and 70 to 130 degreeC is preferable. The PEB time is usually 5 seconds to 600 seconds, and preferably 10 seconds to 300 seconds.

[Development process]
In this step, the resist film exposed in the exposure step is developed using a developer. Thereby, a predetermined resist pattern is formed. Examples of the developer include an alkali developer and a developer containing an organic solvent. The developer can be selected according to the pattern shape to be formed. When a mask pattern is projected onto a resist film by exposure, a positive resist pattern is formed by developing an area with high light irradiation intensity with an alkaline aqueous solution to dissolve and remove the exposed area above a predetermined threshold. Can be formed. On the other hand, when the mask pattern is projected onto the resist film by exposure, an area where the light irradiation intensity is weak is developed with a liquid containing an organic solvent, so that the exposed area below a predetermined threshold is dissolved and removed. A mold resist pattern can be formed. It is also possible to develop by combining these developers depending on the desired resolution and pattern shape.

  Examples of the alkali developer 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, 1,5-diazabicyclo- [4.3.0] -5-Alkaline aqueous solution in which at least one kind of alkaline compound such as nonene is dissolved.

  Examples of the organic solvent contained in the developer containing the organic solvent include one or more of the solvents listed as the [E] solvent of the above-described radiation-sensitive resin composition. Among these, ether solvents, ester solvents, and ketone solvents are preferable. As the ether solvent, an aromatic-containing ether solvent is preferable, and anisole is more preferable. As the ester solvent, an acetate solvent is preferable, and n-butyl acetate is more preferable. As the ketone solvent, a chain ketone solvent is preferable, and 2-heptanone is more preferable.

  As content of the organic solvent in a developing solution, 80 mass% or more is preferable, 90 mass% or more is more preferable, 95 mass% or more is further more preferable, 99 mass% or more is especially preferable. By making the content of the organic solvent in the developer within the above range, the contrast between the exposed part and the unexposed part can be improved, and as a result, while exhibiting a better depth of focus and exposure margin, A resist pattern with smaller LWR and CDU can be formed. Examples of components other than the organic solvent include water and silicone oil.

  An appropriate amount of a surfactant can be added to the developer as necessary. As the surfactant, for example, an ionic or nonionic fluorine-based and / or silicon-based surfactant can be used.

  As a developing method, for example, a method in which a substrate is immersed in a tank filled with a developer for a certain period of time (dip method), a method in which the developer is raised on the surface of the substrate by surface tension and is left stationary for a certain time (paddle method) ), A method of spraying the developer on the substrate surface (spray method), a method of continuously applying the developer while scanning the developer coating nozzle on the substrate rotating at a constant speed (dynamic dispensing method) Etc.

  After the development, it is preferable to rinse with a rinsing liquid such as water or alcohol and then dry. As the rinsing method, for example, a method of continuously applying a rinsing liquid onto a substrate rotating at a constant speed (rotary coating method), a method of immersing the substrate in a tank filled with the rinsing liquid for a certain period of time (dip method) ), A method (spray method) of spraying a rinse liquid on the substrate surface, and the like.

<Polymer>
The polymer of the present invention is a polymer having a first structural unit containing a lactone ring group and a second structural unit containing an acid dissociable group and satisfying the following formula (A).

  In the formula (A), X1 is a gel permeation chromatography elution curve detected by a differential refractometer of the polymer, and the cumulative area area from the high molecular weight side is a% or more and b% with respect to the total area area. (A is an arbitrary value of 0 or more and less than 5; b is an arbitrary value of more than 5 and less than 15) of the first structural unit relative to all the structural units constituting the polymer of the portion It is a value (mol%) of the content ratio. X2 is a cumulative area area from the high molecular weight side of c% or more and d% or less with respect to the total area area (c is an arbitrary value of more than 15 and less than 50. d is an arbitrary value of more than 50 and less than 85 Is the value (mol%) of the content ratio of the first structural unit with respect to all the structural units constituting the polymer of the portion.

  The said polymer has the said 1st structural unit and a 2nd structural unit, and improves the defect inhibitory property of the radiation sensitive resin composition containing this polymer by satisfy | filling the said Formula (A). Can do. Therefore, the polymer can be suitably used as a polymer component of the radiation sensitive resin composition described above.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. The measuring method of various physical property values is shown below.

[Mw, Mn and Mw / Mn]
Mw and Mn use Tosoh GPC columns ("G2000HXL", "G3000HXL" and "G4000HXL"), flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran, sample concentration: 1 0.0 mass%, sample injection amount: 100 μL, column temperature: 40 ° C., detector: measured by 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.

[ ¹³ C-NMR analysis]
The ¹³ C-NMR analysis for determining the content of the structural unit of the polymer was performed under the following conditions.
Apparatus: Nuclear magnetic resonance apparatus ("AVANCE III HD" from Bruker, frequency 700 MHz)
Measurement solvent: Deuterated chloroform Reference substance: Tetramethylsilane paramagnetic relaxation reagent: Tris (2,4-pentandionato) chromium (III): Addition concentration 30 mg / cc
Sample solution concentration: 10 mg / cc
Resonance frequency: 175 MHz
Detection pulse flip angle: 90 °
Data acquisition time: 0.7078 sec
Delay time: 1.2139sec
Integration count: 1800 times (measurement time 1h15min)
Measurement temperature: 25 ° C

<Synthesis of polymer>
The monomers used for polymer synthesis are shown below.

[[A] Synthesis of polymer]
[Example 1] (Synthesis of polymer (A-1))
51.6 g (38 mol%) of the compound (M-1), 40.7 g (20 mol%) of the compound (M-2) and 57.7 g (42 mol%) of the compound (M-3) were added to 200 g of 2- It melt | dissolved in butanone, Furthermore, AIBN 9.28g as a radical polymerization initiator was added, and the monomer solution was prepared. Next, 100 g of 2-butanone was charged into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes. After purging with nitrogen, 2-butanone in the three-necked flask was heated to 60 ° C. with stirring. Subsequently, the monomer solution prepared above was dropped over 4 hours using a dropping funnel. In that case, it controlled so that the temperature of a polymerization reaction liquid rose about 2 degreeC every 20 minutes from dripping start. The temperature of the polymerization reaction liquid at the end of dropping was 82 ° C. After completion of dropping, the mixture was stirred at 82 ° C. for 2 hours.
After completion of the polymerization reaction, the polymerization reaction solution was cooled to 30 ° C. or less by water cooling. Next, 150 g of 2-butanone was added to the polymerization reaction solution, and then poured into 3,000 g of methanol to precipitate a white powder, which was filtered off. The obtained white powder was slurry-washed twice with 600 g of methanol and then filtered off. The obtained white powder was dried at 60 ° C. for 17 hours to obtain a polymer (A-1) (yield 115 g, yield 77%).
Mw of the polymer (A-1) was 6,900, and Mw / Mn was 1.46. As a result of ¹³ C-NMR analysis, the content ratio of the structural unit derived from (M-1): the structural unit derived from (M-2): the structural unit derived from (M-3) was 31.9: 19. 5: 48.6 (mol%).

[Example 2] (Synthesis of polymer (A-2))
60.7 g (50 mol%) of the above compound (M-1) and 89.3 g (50 mol%) of the compound (M-4) were dissolved in 300 g of 2-butanone, and AIBN7. A monomer solution was prepared by adding 11 g. Next, 150 g of 2-butanone was charged into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes. After purging with nitrogen, 2-butanone in the three-necked flask was heated to 70 ° C. with stirring. Subsequently, the monomer solution prepared above was dropped over 4 hours using a dropping funnel. In that case, it controlled so that the temperature of a polymerization reaction liquid rose about 1 degreeC every 20 minutes from dripping start. The temperature of the polymerization reaction liquid at the end of dropping was 82 ° C. After completion of dropping, the mixture was stirred at 82 ° C. for 2 hours.
After completion of the polymerization reaction, the polymerization reaction solution was cooled to 30 ° C. or less by water cooling. Next, 150 g of 2-butanone was added to the polymerization reaction solution, and then poured into 3,000 g of methanol to precipitate a white powder, which was separated by filtration. The obtained white powder was slurry-washed twice with 600 g of methanol and then filtered off. The obtained white powder was dried at 60 ° C. for 17 hours to obtain a polymer (A-2) (yield 122 g, yield 81%).
Mw of the polymer (A-2) was 7,300, and Mw / Mn was 1.46. As a result of ¹³ C-NMR analysis, the content ratio of the structural unit derived from (M-1) :( M-4) was 45.7: 54.3 (mol%).

[Example 3] (Synthesis of polymer (A-3))
64.3 g (50 mol%) of the above compound (M-1) and 85.7 g (50 mol%) of the compound (M-5) were dissolved in 300 g of 2-butanone, and AIBN7. A monomer solution was prepared by adding 53 g. On the other hand, 150 g of 2-butanone was charged into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes. After purging with nitrogen, 2-butanone in the three-necked flask was heated to 70 ° C. with stirring. Subsequently, the monomer solution prepared above was dropped over 4 hours using a dropping funnel. At that time, the temperature of the polymerization reaction solution was controlled to increase by about 1 ° C. every 20 minutes from the start of dropping. The temperature of the polymerization reaction liquid at the end of dropping was 82 ° C. After completion of dropping, the mixture was stirred at 82 ° C. for 2 hours.
After completion of the polymerization reaction, the polymerization reaction solution was cooled to 30 ° C. or less by water cooling. Next, this polymerization reaction liquid was put into 3,000 g of methanol to precipitate a white powder, which was separated by filtration. The obtained white powder was slurry-washed twice with 600 g of methanol and then filtered off. The obtained white powder was dried at 60 ° C. for 17 hours to obtain a polymer (A-3) (yield 119 g, yield 79%).
Mw of the polymer (A-3) was 7,000, and Mw / Mn was 1.44. As a result of ¹³ C-NMR analysis, the content ratio of the structural unit derived from (M-1): structural unit derived from (M-5) was 46.2: 53.8 (mol%).

[Example 4] (Synthesis of polymer (A-4))
64.6 g (50 mol%) of the above compound (M-1) and 85.4 g (50 mol%) of the compound (M-6) were dissolved in 300 g of 2-butanone, and further AIBN.6 as a radical polymerization initiator. A monomer solution was prepared by adding 94 g. On the other hand, 150 g of 2-butanone was charged into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes. After purging with nitrogen, 2-butanone in the three-necked flask was heated to 75 ° C. with stirring. Subsequently, the monomer solution prepared above was dropped over 4 hours using a dropping funnel. In that case, it controlled so that the temperature of a polymerization reaction liquid rose about 1 degreeC every 30 minutes from the dripping start. The temperature of the polymerization reaction liquid at the end of dropping was 82 ° C. After completion of dropping, the mixture was stirred at 82 ° C. for 2 hours.
After completion of the polymerization reaction, the polymerization reaction solution was cooled to 30 ° C. or less by water cooling. Next, this polymerization reaction liquid was put into 3,000 g of methanol to precipitate a white powder, which was separated by filtration. The obtained white powder was slurry-washed twice with 600 g of methanol and then filtered off. The obtained white powder was dried at 60 ° C. for 17 hours to obtain a polymer (A-4) (yield 119 g, yield 79%).
Mw of the polymer (A-4) was 7,100, and Mw / Mn was 1.45. As a result of ¹³ C-NMR analysis, the content ratio of the structural unit derived from (M-1) :( M-5) was 47.5: 52.5 (mol%).

[Synthesis Example 1] (Synthesis of Polymer (A-5))
44.8 g (33.2 mol%) of the above compound (M-1), 37.6 g (18.6 mol%) of the compound (M-2) and 53.5 g (39.2 mol%) of the compound (M-3). ) Was dissolved in 200 g of 2-butanone, and 7.24 g of AIBN as a radical polymerization initiator was further added to prepare a monomer solution. Next, 100 g of 2-butanone, 6.5 g (4.8 mol%) of the above compound (M-1), 5.7 g (2.8 mol%) of compound (M-2) and compound (M-3) 1.9 g (1.4 mol%) was charged into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes. After the nitrogen purge, the solution in the three-necked flask was heated to 80 ° C. with stirring. Subsequently, the monomer solution prepared above was dropped over 4 hours using a dropping funnel. After completion of dropping, the mixture was stirred at 80 ° C. for 2 hours.
After completion of the polymerization reaction, the polymerization reaction solution was cooled to 30 ° C. or less by water cooling. 150 g of 2-butanone was added to this polymerization reaction solution, and then poured into 3,000 g of methanol to precipitate a white powder, which was filtered off. The obtained white powder was slurry-washed twice with 600 g of methanol and then filtered off. The obtained white powder was dried at 60 ° C. for 17 hours to obtain a polymer (A-5) (yield 120 g, yield 80%).
Mw of this polymer (A-5) was 6,500, and Mw / Mn was 1.46. As a result of ¹³ C-NMR analysis, the content ratio of the structural unit derived from (M-1): the structural unit derived from (M-2): the structural unit derived from (M-3) was 33.4: 19.5. : 47.1 (mol%).

[Synthesis Example 2] (Synthesis of polymer (A-6))
58.8 g (45.4 mol%) of the above compound (M-1) and 81.2 g (47.5 mol%) of the compound (M-6) were dissolved in 300 g of 2-butanone, and further a radical polymerization initiator. A monomer solution was prepared by adding 6.95 g of AIBN. Next, 150 g of 2-butanone, 6.9 g (5.3 mol%) of the above compound (M-1) and 3.1 g (1.8 mol%) of the compound (M-6) were added to a 1,000 mL three-necked flask. And purged with nitrogen gas for 30 minutes. After the nitrogen purge, the solution in the three-necked flask was heated to 80 ° C. with stirring. Subsequently, the monomer solution prepared above was dropped over 4 hours using a dropping funnel. After completion of dropping, the mixture was stirred at 80 ° C. for 2 hours.
After completion of the polymerization reaction, the polymerization reaction solution was cooled to 30 ° C. or less by water cooling. This polymerization reaction solution was poured into 3,000 g of methanol to precipitate a white powder, which was filtered off. The obtained white powder was slurry-washed twice with 600 g of methanol and then filtered off. The obtained white powder was dried at 60 ° C. for 17 hours to obtain a polymer (A-6) (yield 122 g, yield 81%).
Mw of the polymer (A-6) was 6,500, and Mw / Mn was 1.45. As a result of ¹³ C-NMR analysis, the content ratio of the structural unit derived from (M-1) :( M-6) was 47.9: 52.1 (mol%).

  The kind and amount (mol%) of the monomer used for the synthesis of the polymers (A-1) to (A-6), the yield (%) of each polymer obtained, Mw, Mw / Mn, and The values of the content ratio (mol%) of each structural unit are shown in Table 1 below.

<Preparation of polymer>
Polymer fractionation was carried out using GPC columns (one “JAI GEL-2.5H” and one “JAI GEL-2H” from Nippon Analytical Industries, Ltd.) under the following conditions.
Apparatus: Preparative GPC (“2535 Quarterly Gradient Module” by Waters)
Column temperature: 40 ° C
Elution solvent: Chloroform (Wako Pure Chemical Industries)
Flow rate: 4.0 mL / min Sample concentration: 15.0% by mass
Sample injection volume: 3.0 mL
Detector: Differential refractometer

The polymer [A] was fractionated into the following fractions by preparative GPC under the above conditions.
Fraction 1 (Fr.1): Partial fraction 2 (Fr.2): polymer in which the accumulated area area from the high molecular weight side is 0% or more and 10% or less with respect to the total area area in the GPC elution curve of the polymer In the GPC elution curve, the fractional area 3 (Fr.3) in which the accumulated area area from the high molecular weight side exceeds 10% and is less than 20% with respect to the total area area: in the GPC elution curve of the polymer Partial fraction 4 (Fr.4) in which the accumulated area area from 20 to 80% of the total area area is the total area area from the high molecular weight side in the GPC elution curve of the polymer Partial fraction 5 (Fr. 5), which is more than 80% and 90% or less, in the GPC elution curve of the polymer, the cumulative area area from the high molecular weight side is Portion serving as 100% or less than 90% with respect to A area

The [A] polymer in each of the obtained fractions was subjected to ¹³ C-NMR analysis under the above conditions.
From the result of the obtained ¹³ C-NMR analysis, the content ratio of each structural unit of the [A] polymer was determined as follows. For example, in the case of the polymer (A-1), in the ¹³ C-NMR chart shown in FIG. 3 obtained, the peak integrated value of 92 ppm derived from the structural unit given by the compound (M-1) and the compound (M− The content ratio of the structural unit (I) and the structural unit (II) from the peak integrated value of 67 ppm derived from the structural unit given by 2) and the peak integrated value of 73 ppm derived from the structural unit given by the compound (M-3) (Mol%) was calculated respectively.

  In Table 2 below, using the above method, the content of the structural unit derived from each compound in the [A] polymer in each fraction obtained by fractionating the polymers (A-1) to (A-6) Indicates.

[[D] Synthesis of polymer]
[Synthesis Example 3] (Synthesis of Polymer (D-1))
58.2 g (40 mol%) of the above compound (M-7) and 91.9 g (60 mol%) of the compound (M-8) are dissolved in 200 g of 2-butanone, and further 5.32 g of AIBN as a radical polymerization initiator. Was added to prepare a monomer solution. Next, 100 g of 2-butanone was charged into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes. After purging with nitrogen, the inside of the three-necked flask was heated to 80 ° C. while stirring. Next, the monomer solution prepared above was dropped over 3 hours using a dropping funnel. After completion of dropping, the mixture was stirred at 80 ° C. for 3 hours.
After completion of the polymerization reaction, the polymerization reaction solution was cooled to 30 ° C. or less by water cooling. This polymerization reaction liquid was put into 3,000 g of a mixed liquid of methanol and water (mass ratio 1: 1) to precipitate a white viscous solid, which was separated by filtration. The obtained white viscous solid was washed twice with 600 g of a mixture of methanol and water (mass ratio 1: 1), and then filtered off. The obtained white viscous solid was dried at 60 ° C. for 17 hours to obtain a colorless solid polymer (D-1) (yield 78 g, yield 52%).
Mw of this polymer (D-1) was 6,600, and Mw / Mn was 1.51. As a result of ¹³ C-NMR analysis, the content ratio of the structural unit derived from (M-7) and the structural unit derived from (M-8) was 38:62 (mol%), respectively.

<Preparation of radiation-sensitive resin composition>
The [B] acid generator, [C] acid diffusion controller, [E] solvent, and [F] uneven distribution accelerator used for the preparation of the radiation sensitive resin composition are shown below.

[[B] acid generator]
B-1: Triphenylsulfonium 1,1,2,2-tetrafluoro-6- (1-adamantanecarbonyloxy) hexane-1-sulfonate (compound represented by the following formula (B-1))

[[C] acid diffusion controller]
C-1: Triphenylsulfonium 6-methyl-4-oxo-1,2,3-oxathiazine-3-id-2,2-dioxide (compound represented by the following formula (C-1))

[[E] solvent]
E-1: Propylene glycol monomethyl ether acetate

[[F] uneven distribution promoter]
F-1: γ-butyrolactone

[Example 5]
[A] 100 parts by mass of (A-1) as a polymer, [B] 8.5 parts by mass of (B-1) as an acid generator, [C] (C-1) 5 as an acid diffusion controller 1 part by weight, 2.0 parts by weight of (D-1) as a [D] polymer, 3,191 parts by weight of (E-1) as a solvent [E] and (F) ( F-1) 200 parts by mass was mixed, and the resulting mixture was filtered through a membrane filter having a pore size of 0.2 μm to prepare a radiation sensitive resin composition (J-1).

[Examples 6 to 8 and Comparative Examples 1 and 2]
Except having used each component of the kind and content shown in following Table 3, it operated similarly to Example 5 and the radiation sensitive resin composition (J-2)-(J-4) and (CJ-1). ) And (CJ-2) were prepared.

<Formation of resist pattern>
A 12-inch silicon wafer surface was coated with a composition for forming a lower antireflection film (“ARC66” from Brewer Science Co., Ltd.) using a spin coater (“CLEAN TRACK ACT12” from Tokyo Electron), and then 205 ° C. Was heated for 60 seconds to form a lower antireflection film having a thickness of 105 nm. On the lower antireflection film, the prepared radiation sensitive resin composition was applied using the spin coater, and PB was performed at 100 ° C. for 60 seconds. Then, it cooled at 23 degreeC for 30 second, and formed the resist film with a film thickness of 90 nm. Next, this resist film was subjected to an optical condition of NA = 1.3 and dipole (Sigma 0.977 / 0.782) using an ArF excimer laser immersion exposure apparatus (“NSR-S610C” manufactured by NIKON). , And exposed through a mask pattern for forming 42 nm line and space (1L1S). After exposure, PEB was performed at 95 ° C. for 60 seconds. Thereafter, the resist was alkali-developed using a 2.38 mass% TMAH aqueous solution as an alkali developer, washed with water, and dried to form a positive resist pattern. When this resist pattern was formed, an exposure amount at which a one-to-one line and space with a line width of 42 nm was formed was determined as an optimum exposure amount using a one-to-one line and space mask with a target dimension of 42 nm. A line and space resist pattern having a line width of 42 nm was formed on the entire surface of the wafer with this optimum exposure amount.

<Evaluation>
About the formed resist pattern, the following evaluation was performed in accordance with the following method. The evaluation results are shown in Table 4 below.
[Defect suppression]
The number of defects on the obtained resist pattern was measured using a defect inspection apparatus (“KLA2810” manufactured by KLA-Tencor). Furthermore, the defects measured by the defect inspection apparatus were classified into those determined to be resist-derived and foreign matters derived from the outside. The total number of defects determined to be derived from the resist was calculated and used as the number of defects (pieces).

[LWR performance]
When observing a resist pattern with 42nm line / 82nm pitch resolved at the optimum exposure dose from the top of the pattern with a length measurement SEM ("CG4000" from Hitachi, Ltd.), the line width is 10 points at an arbitrary point. Observed and the value of the distribution of the measured values expressed as 3 sigma was defined as LWR performance (nm). It can be determined that the smaller the value, the better the line width uniformity of the pattern after development.

[EL performance]
When the mask pattern for forming a resist pattern of 42 nm line and space (1L / 1S) is used, the resist pattern dimension resolved is within ± 10% of the mask design dimension. The ratio (10% EL) to the optimum exposure amount was defined as EL performance (%). It can be determined that the larger the value of the EL performance is, the smaller the change amount of the patterning performance with respect to the exposure amount change is.

  As can be seen from the results in Table 4 above, according to the radiation-sensitive resin composition of the example, a resist pattern with few defects can be obtained while maintaining the LWR performance and the EL performance.

  According to the radiation sensitive resin composition and the resist pattern forming method of the present invention, a resist pattern with few defects can be formed. Therefore, these can be suitably used for manufacturing processes of semiconductor devices that are expected to be further miniaturized in the future.

Claims (6)

A first polymer having a first structural unit containing a lactone ring group and a second structural unit containing an acid dissociable group ;
A radiation sensitive acid generator , and
A radiation-sensitive resin composition containing a second polymer having a fluorine content higher than that of the first polymer ,
The said 1st polymer satisfy | fills following formula (A), The radiation sensitive resin composition characterized by the above-mentioned.

(In formula (A), X1 is a gel permeation chromatography elution curve detected by the differential refractometer of the first polymer, and the cumulative area area from the high molecular weight side is a% or more with respect to the total area area. b% or less (a is .b an arbitrary value from 0 to less than 5 is any value less than 15 more than 5.) the relative total structural units constituting the first polymer of the portion to be the 1 is a content value (mol%) of a structural unit, where X2 is a cumulative area area from the high molecular weight side of not less than c% and not more than d% with respect to the total area area. D is an arbitrary value greater than 50 and less than or equal to 85.) The content ratio (mol%) of the first structural unit relative to all the structural units constituting the first polymer in the portion is there.)   The radiation-sensitive resin composition according to claim 1, wherein the right side of the formula (A) is 0.05.   The radiation-sensitive resin composition according to claim 1 or 2, wherein the lactone ring group has a higher ring-opening reaction rate with an alkali than the unsubstituted norbornane lactone ring group.   The lactone ring group is a monocyclic lactone ring group, a polycyclic lactone ring group substituted with an electron withdrawing group, or a polycyclic lactone ring group containing an oxygen atom or a sulfur atom in a ring other than the lactone ring. The radiation-sensitive resin composition according to claim 1 or 2. The radiation-sensitive resin composition according to any one of claims 1 to 4, wherein the second structural unit is represented by the following formula (1).

(In Formula (1), R is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ^p is a monovalent acid-dissociable group having 1 to 30 carbon atoms.) Forming a resist film;
A step of exposing the resist film, and a step of developing the exposed resist film,
A resist pattern forming method, wherein the resist film is formed from the radiation-sensitive resin composition according to any one of claims 1 to 5.

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