JP6369301B2 - Radiation-sensitive resin composition and resist pattern forming method - Google Patents

Description

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

  For forming various electronic devices such as semiconductor devices and liquid crystal devices, a resist pattern forming method by photolithography is used. In this resist pattern forming method, for example, a radiation sensitive resin composition for forming a resist pattern on a substrate is used. The radiation-sensitive resin composition generates an acid in an exposed portion by irradiation with radiation such as deep ultraviolet rays such as ArF excimer laser light, electromagnetic waves such as extreme ultraviolet rays (EUV: Extreme Ultraviolet), electron beams, and the like. The action causes a difference in 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 can not only form a resist pattern with high resolution and excellent rectangular shape in cross section, but also has excellent LWR (Line Width Roughness) performance, depth of focus, etc., and a high precision pattern with a high yield. Is required to be obtained. In response to this requirement, various structures of the polymer contained in the radiation-sensitive resin composition have been studied. By having a lactone structure such as a butyrolactone structure or a norbornane lactone structure, the resist pattern can be adhered to the substrate. It is known that these properties can be improved while improving the performance (see JP-A-11-212265, JP-A-2003-5375 and JP-A-2008-83370).

  However, at the present time when the resist pattern is miniaturized to a level of 40 nm or less, the required level of the performance is further increased, and the conventional radiation-sensitive resin composition does not satisfy these requirements. Not done. Recently, in order to secure the film thickness of the resist film and further improve the above-described resolution and the like, it is possible to suppress the shrinkage of the resist film during post-exposure heating (PEB: Post Exposure Bake), that is, the film shrinkage. There is also a demand for excellent suppression.

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

  The present invention has been made based on the circumstances as described above, and its purpose is a radiation-sensitive resin composition that is excellent in resolution, rectangularity in cross-sectional shape, LWR performance, depth of focus, and film shrinkage suppression. And a resist pattern forming method.

（式（１）中、Ｘは、下記式（１−ａ）又は（１−ｂ）で表される１価の基である。Ｒ^１及びＲ^２は、それぞれ独立して、水素原子又はメチル基である。Ｒ^３は、水素原子又は炭素数１〜３０の１価の有機基である。ｎは、１〜５の整数である。）

（式（１−ａ）中、Ｒ^４及びＲ^５は、それぞれ独立して、−ＣＮ、−ＮＯ_２、炭素数１〜３０の１価のフッ素化炭化水素基、極性基で置換されている炭素数１〜３０の１価の炭化水素基又は−Ｙ−Ｚで表される１価の基である。Ｙは、−ＣＯ−、−ＣＯＯ−、−ＳＯ_２−又は−ＳＯ_２Ｏ−である。Ｚは、炭素数１〜３０の１価の有機基である。Ｒ^６は、水素原子、フッ素原子、−ＮＯ_２又はＲ^４、Ｒ^５及びＲ^６が結合する炭素原子に隣接する炭素原子、窒素原子若しくは硫黄原子を含む炭素数１〜３０の１価の有機基である。Ｒ^４、Ｒ^５及びＲ^６のうちの２以上は、互いに合わせられこれらが結合する炭素原子と共に環員数３〜２０の環構造を形成していてもよい。Ｙが複数の場合、複数のＹは同一でも異なっていてもよい。Ｚが複数の場合、複数のＺは同一でも異なっていてもよい。＊は、第１構造単位のＸ以外の部分に結合する部位を示す。
式（１−ｂ）中、Ｒ^４及びＲ^５は、それぞれ独立して、−ＣＮ、−ＮＯ_２、炭素数１〜３０の１価のフッ素化炭化水素基、極性基で置換されている炭素数１〜３０の１価の炭化水素基又は−Ｙ−Ｚで表される１価の基である。Ｙは、−ＣＯ−、−ＣＯＯ−、−ＳＯ_２−又は−ＳＯ_２Ｏ−である。Ｚは、炭素数１〜３０の１価の有機基である。Ｒ^４及びＲ^５は、互いに合わせられこれらが結合する窒素原子と共に環員数３〜２０の環構造を形成していてもよい。Ｙが複数の場合、複数のＹは同一でも異なっていてもよい。Ｚが複数の場合、複数のＺは同一でも異なっていてもよい。＊は、第１構造単位のＸ以外の部分に結合する部位を示す。） The invention made in order to solve the above-mentioned problems is a first polymer having a first structural unit represented by the following formula (1) (hereinafter also referred to as “structural unit (I)”) (hereinafter referred to as “[A ] Polymer "), a radiation sensitive acid generator (hereinafter also referred to as" [B] acid generator ") and a solvent (hereinafter also referred to as" [C] solvent "). It is a thing.

(In formula (1), X is a monovalent group represented by the following formula (1-a) or (1-b). R ¹ and R ² are each independently a hydrogen atom or methyl. R ³ is a hydrogen atom or a monovalent organic group having 1 to 30 carbon atoms, and n is an integer of 1 to 5.)

(In Formula (1-a), R ⁴ and R ⁵ are each independently substituted with —CN, —NO ₂ , a monovalent fluorinated hydrocarbon group having 1 to 30 carbon atoms, or a polar group. a monovalent monovalent group represented by a hydrocarbon group or a -Y-Z C1-30 .Y is, -CO -, - COO -, - SO 2 - or _-SO 2 O-in carbon some .Z is .R ⁶ is a monovalent organic group having 1 to 30 carbon atoms, which is adjacent to the hydrogen atom, a fluorine atom, the carbon atom to which -NO _2, or ^R 4, ^{R 5} and ^{R 6} are bonded It is a C1-C30 monovalent organic group containing an atom, a nitrogen atom or a sulfur atom, and two or more of R ⁴ , R ⁵ and R ⁶ are combined with each other and the number of ring members together with the carbon atom to which they are bonded. It may form a ring structure of 3 to 20. When Y is plural, the plural Ys may be the same or different. A plurality of cases, the plurality of Z in different may. * Also identical, indicating the site that binds to a portion other than the X of the first structural unit.
In formula (1-b), R ⁴ and R ⁵ each independently represent —CN, —NO ₂ , carbon having 1 to 30 carbon atoms substituted with a monovalent fluorinated hydrocarbon group or polar group. It is a monovalent hydrocarbon group represented by the formula 1-30, or a monovalent group represented by -YZ. Y is, -CO -, - COO -, - SO 2 - or _-SO 2 is O-. Z is a monovalent organic group having 1 to 30 carbon atoms. R ⁴ and R ⁵ may be combined with each other to form a ring structure having 3 to 20 ring members together with the nitrogen atom to which they are bonded. When Y is plural, the plural Ys may be the same or different. When there are a plurality of Zs, the plurality of Zs may be the same or different. * Indicates a site that binds to a portion other than X of the first structural unit. )

  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.

  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, the alicyclic hydrocarbon group does not need 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, the aromatic hydrocarbon group does not need to be composed only of an aromatic ring structure, and a part thereof may include a chain structure or an alicyclic structure. “Organic group” refers to a group containing at least one carbon atom. “Number of ring members” means the number of atoms constituting the ring of an aromatic ring structure, aromatic heterocyclic structure, alicyclic structure and aliphatic heterocyclic structure. In the case of a polycyclic ring structure, this polycyclic ring The number of atoms to be played.

  According to the radiation-sensitive resin composition and resist pattern forming method of the present invention, a resist pattern that exhibits excellent depth of focus and film shrinkage suppression, high resolution, low LWR, and excellent cross-sectional rectangularity. Can be formed. Accordingly, these can be suitably used for manufacturing semiconductor devices that are expected to be further miniaturized in the future.

<Radiation sensitive resin composition>
The radiation sensitive resin composition contains a [A] polymer, a [B] acid generator, and a [C] solvent. In addition, the radiation-sensitive resin composition includes a [D] acid diffusion controller and a second polymer having a fluorine atom content larger than that of the [A] polymer (hereinafter referred to as “[E] polymer”) as suitable components. And [F] an uneven distribution promoter, and may contain other optional components 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). Since the [A] polymer has the structural unit (I), the radiation-sensitive resin composition is excellent in resolution, rectangular cross-sectional shape, LWR performance, depth of focus, and film shrinkage suppression. The reason why the radiation-sensitive resin composition exhibits the above-described effect by having the above-described configuration is not necessarily clear, but can be inferred as follows, for example. That is, the [A] polymer has moderately high rigidity because the two groups R ⁴ and R ⁵ having high polarity are located in the vicinity of the main chain. As a result, according to the radiation sensitive resin composition, the diffusion length of the acid generated from the [B] acid generator can be appropriately shortened, so that the resolution and the LWR performance are excellent. Moreover, according to the said radiation sensitive resin composition, shrinkage | contraction of a resist film at the time of PEB etc. can be suppressed by the moderately high rigidity of [A] polymer. Furthermore, it is considered that the rectangularity of the cross-sectional shape and the depth of focus are improved by the rigidity and the like.

  [A] In addition to the structural unit (I), the polymer may be a second structural unit containing an acid dissociable group (hereinafter, also referred to as “structural unit (II)”), a lactone structure, a cyclic carbonate structure, a sultone structure, or the like. A third structural unit (hereinafter also referred to as “structural unit (III)”), a structural unit (IV) containing an alcoholic hydroxyl group, a structural unit (V) containing a phenolic hydroxyl group, or a combination thereof. Is preferred. Here, the “acid-dissociable group” refers to a group that substitutes a hydrogen atom of a carboxy group or a phenolic hydroxyl group and dissociates by the action of an acid. [A] The polymer may have other structural units other than the structural units (I) to (V). [A] The polymer may have one or more of the above structural units. Hereinafter, each structural unit will be described.

[Structural unit (I)]
The structural unit (I) is represented by the following formula (1).

In the above formula (1), X is a monovalent group represented by the following formula (1-a) or (1-b). R ¹ and R ² are each independently a hydrogen atom or a methyl group. R ³ is a hydrogen atom or a monovalent organic group having 1 to 30 carbon atoms. n is an integer of 1-5.

In the above formula (1-a), R ⁴ and R ⁵ are each independently substituted with —CN, —NO ₂ , a monovalent fluorinated hydrocarbon group having 1 to 30 carbon atoms, or a polar group. A monovalent hydrocarbon group having 1 to 30 carbon atoms or a monovalent group represented by -Y-Z. Y is, -CO -, - COO -, - SO 2 - or _-SO 2 is O-. Z is a monovalent organic group having 1 to 30 carbon atoms. R ⁶ is a hydrogen atom, a fluorine atom, —NO _2, or a C 1-30 monovalent organic containing a carbon atom, a nitrogen atom or a sulfur atom adjacent to the carbon atom to which R ⁴ , R ⁵ and R ⁶ are bonded. It is a group. Two or more of R ⁴ , R ⁵ and R ⁶ may be combined with each other to form a ring structure having 3 to 20 ring members together with the carbon atom to which they are bonded. When Y is plural, the plural Ys may be the same or different. When there are a plurality of Zs, the plurality of Zs may be the same or different. * Indicates a site that binds to a portion other than X of the first structural unit.

In the above formula (1-b), R ⁴ and R ⁵ are each independently substituted with —CN, —NO ₂ , a monovalent fluorinated hydrocarbon group having 1 to 30 carbon atoms, or a polar group. A monovalent hydrocarbon group having 1 to 30 carbon atoms or a monovalent group represented by -Y-Z. Y is, -CO -, - COO -, - SO 2 - or _-SO 2 is O-. Z is a monovalent organic group having 1 to 30 carbon atoms. R ⁴ and R ⁵ may be combined with each other to form a ring structure having 3 to 20 ring members together with the nitrogen atom to which they are bonded. When Y is plural, the plural Ys may be the same or different. When there are a plurality of Zs, the plurality of Zs may be the same or different. * Indicates a site that binds to a portion other than X of the first structural unit.

As said R < ¹ > and R < ² >, a hydrogen atom is preferable from a copolymerizable viewpoint of a [A] polymer.

Examples of the monovalent organic group having 1 to 30 carbon atoms represented by R ³ include a monovalent hydrocarbon group having 1 to 30 carbon atoms, and a heteroatom-containing group between carbon-carbons of the hydrocarbon group. And a group in which some or all of the hydrogen atoms of these groups are substituted with a substituent. Here, the “hetero atom” refers to an atom other than a carbon atom and a hydrogen atom.

  Examples of the monovalent hydrocarbon group having 1 to 30 carbon atoms include a monovalent chain hydrocarbon group having 1 to 30 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 30 carbon atoms, and the number of carbon atoms. Examples thereof include 6-30 monovalent aromatic hydrocarbon groups.

Examples of the monovalent chain hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, and a t-butyl group. An alkyl group;
An alkenyl group such as an ethenyl group, a propenyl group, a butenyl group;
Examples thereof include alkynyl groups such as ethynyl group, propynyl group and butynyl group.

Examples of the monovalent alicyclic hydrocarbon group include monocyclic cycloalkyl groups such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cyclooctyl group;
A monocyclic cycloalkenyl group such as a cyclobutenyl group, a cyclopentenyl group, or a cyclohexenyl 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, a tricyclodecenyl group, and a tetracyclododecenyl group.

Examples of the monovalent aromatic hydrocarbon group include aryl groups such as phenyl group, tolyl group, xylyl group, naphthyl group, and anthryl group;
Examples include aralkyl groups such as benzyl group, phenethyl group, phenylpropyl group, naphthylmethyl group, and the like.

Examples of the hetero atom-containing group include —CO—, —CS—, —O—, —S—, —NR ″ —, —COO—, —SO ₂ —, —SO ₂ O—, or a combination thereof. R ″ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

Examples of the substituent include halogen atoms such as fluorine atom, chlorine atom, bromine atom and iodine atom;
Carboxy group, hydroxy group, carbonyl group, alkoxy group, cycloalkoxy group, aryloxy group, alkoxycarbonyl group, cycloalkyloxyoxycarbonyl group, aryloxycarbonyl group, acyl group, amino group, amide group, cyano group, isocyanate group And polar groups such as a sulfo group.

The substituent may be an ionic group formed by a combination of a cation group and an anion, or a combination of an anion group and a cation. Examples of the cationic group, e.g., _{^{- (NR X 4) +,}} - (SR X 2) +, - include ^{(IR X) +} and the like. R ^X is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. Examples of the anion include F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , perchlorate ion, hydrogen sulfate ion, dihydrogen phosphate ion, tetrafluoroborate ion, aliphatic sulfonate ion, and aromatic sulfonic acid. Ions, trifluoromethanesulfonic acid ions, fluorosulfonic acid ions, hexafluorophosphoric acid ions, hexachloroantimonic acid ions, and the like. Examples of the anionic group, for example _-SO ³ -, -COO ^-, and the like. Examples of the cation include onium cations such as a sulfonium cation, a phosphonium cation, an ammonium cation, and an iodonium cation. The onium cation may be a radiation-sensitive onium cation contained in the [B] acid generator described later.

R ³ may be an acid dissociable group or a non-acid dissociable group. R ³ may include a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination thereof.

R ³ is preferably a non-acid-dissociable group, more preferably a substituted or unsubstituted hydrocarbon group, a hydrocarbon group in which some or all of the hydrogen atoms are substituted with hydroxy groups or fluorine atoms, and unsubstituted The hydrocarbon group is more preferable, and an alkyl group in which part or all of the hydrogen atoms are substituted with a hydroxy group or a fluorine atom, and an unsubstituted alkyl group are particularly preferable.

The lower limit of the number of carbon atoms in the R ^3, 1 is preferred, 2 is more preferable. The upper limit of the carbon number of R ³ is preferably 20, more preferably 10, more preferably 5, and particularly preferably 3.

Examples of the monovalent fluorinated hydrocarbon group having 1 to 30 carbon atoms represented by R ⁴ and R ⁵ include, for example, a monovalent chain hydrocarbon group having 1 to 30 carbon atoms and 1 to 3 to 30 carbon atoms. Examples include a group in which part or all of hydrogen atoms such as a valent alicyclic hydrocarbon group and a monovalent aromatic hydrocarbon group having 6 to 30 carbon atoms are substituted with fluorine atoms.

Examples of the monovalent hydrocarbon group having 1 to 30 carbon atoms substituted with the polar group of R ⁴ and R ⁵ include, for example, a part or all of the hydrogen atoms of the monovalent hydrocarbon group are polar groups. Examples include substituted groups.

  Examples of the polar group include carboxy group, hydroxy group, carbonyl group, alkoxy group, cycloalkoxy group, aryloxy group, alkoxycarbonyl group, cycloalkyloxyoxycarbonyl group, aryloxycarbonyl group, acyl group, amino group, amide Group, cyano group, isocyanate group, sulfo group and the like. Note that halogen atoms such as fluorine atom, bromine atom and chlorine atom are not included in the polar group.

Examples of the monovalent organic group represented by Z include the same groups as the monovalent organic group represented by R ³ .

As said R < ⁴ > and R < ⁵ >, the monovalent group represented by -YZ is preferable. Y is preferably —CO—. Z is preferably a substituted or unsubstituted hydrocarbon group, more preferably a fluorinated hydrocarbon group and an unsubstituted hydrocarbon group, more preferably a fluorinated alkyl group and an alkyl group, a trifluoromethyl group and a methyl group. Is particularly preferred.

Examples of the monovalent organic group having 1 to 30 carbon atoms represented by R ⁶ include the same groups as the monovalent organic group represented by R ³ .

R ⁶ is preferably a hydrogen atom or a hydrocarbon group, more preferably a hydrogen atom, an aromatic hydrocarbon group or a chain hydrocarbon group, still more preferably a hydrogen atom, an aryl group or an alkyl group, a hydrogen atom, a phenyl group. A methyl group and an ethyl group are particularly preferable, and a hydrogen atom is further particularly preferable.

The upper limit of the carbon number of the organic group represented by R ⁶ is preferably 20, more preferably 10, more preferably 6, and particularly preferably 3.

In the above formula (1-a), the ring structure having 3 to 20 ring members composed of two or more of R ⁴ , R ⁵ and R ⁶ together with the carbon atom to which they are bonded includes, for example, fat Examples thereof include a ring structure, an aliphatic heterocyclic structure, an aromatic ring structure, and an aromatic heterocyclic structure.

Examples of the alicyclic structure include monocyclic cycloalkane structures such as a cyclopropane structure, a cyclobutane structure, a cyclopentane structure, a cyclohexane structure, a cycloheptane structure, and a cyclooctane structure;
Examples thereof include polycyclic cycloalkane structures such as a norbornane structure, an adamantane structure, a tricyclodecane structure, and a tetracyclododecane structure.

Examples of the aliphatic heterocyclic structure include azacycloalkane structures such as an azacyclopentane structure and an azacyclohexane structure;
Oxacycloalkane structures such as oxacyclopentane structure and oxacyclohexane structure;
Thiacycloalkane structures such as a thiacyclopentane structure and a thiacyclohexane structure;
Examples include oxazolidine, 1,4,2-dioxazolidine, thiazolidine and the like.

  Examples of the aromatic ring structure include a benzene ring structure, a naphthalene ring structure, an anthracene structure, and a phenanthrene structure.

  Examples of the aromatic heterocyclic structure include a furan structure, a pyridine structure, a quinoline structure, a pyrrole structure, an indole structure, a carbazole structure, a thiophene structure, an oxazole structure, and an isothiazole structure.

In the above formula (1-b), examples of the ring structure having 3 to 20 ring members constituted by the nitrogen atom to which R ⁴ and R ⁵ are combined and bonded to each other include, for example, an aliphatic heterocyclic structure and an aromatic heterocyclic structure. Examples thereof include a ring structure. Examples of the aliphatic heterocyclic structure and aromatic heterocyclic structure include structures similar to the aliphatic heterocyclic structure and aromatic heterocyclic structure exemplified in Formula (1-a).

  As said n, 1 and 2 are preferable and 1 is more preferable from a viewpoint which raises the rigidity of the principal chain of a [A] polymer more appropriately.

  As the structural unit (I), for example, structural units represented by the following formulas (I-1) to (I-21) (hereinafter also referred to as “structural units (I-1) to (I-21)”) and the like Is mentioned.

In the above formulas (I-1) to (I-21), R ^{1 to} R ³ have the same meaning as the above formula (1).

  As a minimum of the content rate of structural unit (I), 1 mol% is preferable with respect to all the structural units which comprise a [A] polymer, 3 mol% is more preferable, 6 mol% is further more preferable, 8 mol % Is particularly preferred. On the other hand, the upper limit of the content ratio of the structural unit (I) is preferably 30 mol%, more preferably 20 mol%, still more preferably 15 mol%, based on all structural units constituting the [A] polymer. 12 mol% is particularly preferred. By setting the content ratio of the structural unit (I) in the above range, it is possible to further improve the resolution, the rectangular shape of the cross-sectional shape, the LWR performance, the depth of focus, and the film shrinkage suppression property of the radiation-sensitive resin composition. it can.

  Examples of the monomer that gives the structural unit (I) include a compound represented by the following formula (i) (hereinafter also referred to as “compound (i)”).

In the above formula ^(i), R 1 ^{to R} 3, X and n have the same meanings as in formula (1).

  Examples of the compound (i) include compounds represented by the following formulas.

Compound (i) can be synthesized, for example, according to the following scheme when X is a monovalent group represented by formula (1-a).

In the above scheme, J is a halogen atom. R < ¹ > -R < ⁶ > and n are synonymous with the said Formula (1).

  As a halogen atom represented by said J, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom etc. are mentioned, for example, Among these, a bromine atom is preferable.

  A polymerizable carbon-carbon double bond-containing compound represented by the above formula (ia) and an active methylene compound represented by the above formula (ib) in the presence of a base such as potassium carbonate, tetrahydrofuran, etc. Compound (i ′) can be obtained by reacting in the above solvent. The compound (i ') can be isolated by appropriately purifying the obtained product by column chromatography, recrystallization, distillation or the like.

  Compound (i) other than compound (i ′) can also be synthesized by the same method.

[Structural unit (II)]
The structural unit (II) is a structural unit containing an acid dissociable group (except for those corresponding to the structural unit (I)). [A] Since the polymer has the structural unit (II), the dissolution contrast between the exposed portion and the unexposed portion can be adjusted to an appropriate value. As a result, the resolution of the radiation-sensitive resin composition can be improved. Property, rectangularity of the cross-sectional shape, and LWR performance can be further improved.

  Examples of the structural unit (II) include a structural unit represented by the following formula (3-1) (hereinafter also referred to as “structural unit (II-1)”) and a structure represented by the following formula (3-2). Unit (hereinafter also referred to as “structural unit (II-2)”) and the like.

In the formula (3-1), ^{R 7} is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ⁸ is a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ⁹ and R ¹⁰ are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms, or the number of ring members 3 to 20 configured together with the carbon atoms to which these groups are combined with each other. Represents an alicyclic structure.

In the formula ^{(3-2), R 11} is hydrogen atom or a methyl group. L ¹ is a single bond, —COO— or —CONH—. R ¹² is a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. R ¹³ and R ¹⁴ are each independently a monovalent hydrocarbon group having 1 to 20 carbon atoms or a monovalent oxyhydrocarbon group having 1 to 20 carbon atoms.

R ⁷ is preferably a hydrogen atom and a methyl group, more preferably a methyl group, from the viewpoint of copolymerization of the monomer that gives the structural unit (II-1).

R ¹¹ is preferably a methyl group from the viewpoint of copolymerization of the monomer that gives the structural unit (II-2).

As a C1-C20 monovalent hydrocarbon group represented by said R < ⁸ > -R < ¹⁰ > and R < ¹² > -R < ¹⁴ >, the group similar to the hydrocarbon group illustrated by said R < ³ >, etc. are mentioned, for example.

Examples of the monovalent oxyhydrocarbon group having 1 to 20 carbon atoms represented by R ¹² , R ¹³ and R ¹⁴ include alkoxy groups such as a methoxy group, an ethoxy group, a propoxy group, and a butoxy group;
Alkenyloxy groups such as ethenyloxy group, propenyloxy group, butenyloxy group;
Monovalent oxy-chain hydrocarbon groups such as alkynyloxy groups such as ethynyloxy group, propynyloxy group, butynyloxy group, etc.
Monocyclic cycloalkyloxy groups such as cyclopropyloxy group, cyclobutyloxy group, cyclopentyloxy group, cyclohexyloxy group;
A monocyclic cycloalkenyloxy group such as a cyclopropenyloxy group, a cyclobutenyloxy group, a cyclopentenyloxy group;
A polycyclic cycloalkyloxy group such as a norbornyloxy group, an adamantyloxy group, a tricyclodecanyloxy group, a tetracyclododecyloxy group;
Monovalent oxyalicyclic hydrocarbon groups such as polycyclic cycloalkenyloxy groups such as norbornenyloxy group, tricyclodecenyloxy group, tetracyclododecenyloxy group, etc.,
Aryloxy groups such as phenoxy group, tolyloxy group, xylyloxy group, mesityloxy group, naphthyloxy group;
Examples thereof include aralkyloxy groups such as benzyloxy group, phenethyloxy group, phenylpropyloxy group and naphthylmethyloxy group.

Examples of the alicyclic structure having 3 to 20 ring members configured together with the carbon atoms to which R ⁹ and R ¹⁰ are combined and bonded to each other are the same as the alicyclic structures exemplified for R ⁴ , R ⁵ and R ⁶ above. And the like.

  As the structural unit (II-1), structural units represented by the following formulas (3-1-1) to (3-1-5) (hereinafter referred to as “structural units (II-1-1) to (II— 1-5) ") is preferred. As the structural unit (II-2), a structural unit represented by the following formula (3-2-1) (hereinafter also referred to as “structural unit (II-2-1)”) is preferable.

In the above formulas (3-1-1) to (3-1-5), R ^{7 to} R ¹⁰ have the same meaning as the above formula (3-1). R ^{8 ′} , R ^{9 ′} and R ^{10 ′} are each independently a monovalent chain hydrocarbon group having 1 to 10 carbon atoms. n _p is each independently an integer of 1 to 4.

In the above formula ^(3-2-1), R 11 ^{to R 14} is as defined in the above formula (3-2).

Examples of the structural units (II-1-1) to (II-1-5) include structural units represented by the following formulas.

In the above formula, R ⁷ has the same meaning as the above formula (3-1).

  Among these, structural units derived from 2-alkyl-2-adamantyl (meth) acrylate, structural units derived from 1-alkyl-1-cyclopentyl (meth) acrylate, 2- (1-adamantyl) -2-propyl Structural unit derived from (meth) acrylate, structural unit derived from 2-alkyl-2-tetracyclododecan-yl (meth) acrylate, structure derived from 2- (1-cyclohexyl) -2-propyl (meth) acrylate A unit, a structural unit derived from t-decane-yl (meth) acrylate and a structural unit derived from 1-alkyl-1-cyclooctyl (meth) acrylate are preferred.

  Examples of the structural unit (II-2) include a structural unit represented by the following formula.

In the above formula, R ¹¹ has the same meaning as the above formula (3-2).

  As the structural unit (II-2), a structural unit derived from p- (1-cyclohexylethoxyethoxy) styrene is preferable.

  [A] When the polymer has the structural unit (II), the lower limit of the content ratio of the structural unit (II) is preferably 10 mol% with respect to the total structural units constituting the [A] polymer, More preferably, mol% is more preferable, 30 mol% is further more preferable, and 40 mol% is especially preferable. On the other hand, the upper limit of the content ratio of the structural unit (II) is preferably 90 mol%, more preferably 80 mol%, still more preferably 70 mol%, based on all structural units constituting the [A] polymer. 60 mol% is particularly preferred. By making the content rate of structural unit (II) into the said range, the resolution of the said radiation sensitive resin composition, the rectangularity of a cross-sectional shape, and LWR performance can further be improved.

[Structural unit (III)]
The structural unit (III) is a structural unit containing a lactone structure, a cyclic carbonate structure, a sultone structure or a combination thereof (except for those corresponding to the structural unit (I)). [A] The polymer further has the structural unit (III), so that the solubility in the developer can be adjusted to an appropriate level. As a result, the resolution of the radiation-sensitive resin composition, The rectangularity of the cross-sectional shape and the LWR performance can be further improved. Moreover, the adhesiveness of the resist film formed from the said radiation sensitive resin composition and a board | substrate can be improved. Here, the lactone structure refers to a structure having a ring (lactone ring) containing a group represented by —O—C (O) —. The cyclic carbonate structure refers to a structure having a ring (cyclic carbonate ring) containing a group represented by —O—C (O) —O—. The sultone structure refers to a structure having a ring (sultone ring) containing a group represented by —O—S (O) ₂ —.

  Examples of the structural unit (III) 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.

  Among these, the structural unit (III) is preferably a structural unit containing a lactone structure, more preferably a structural unit containing a norbornane lactone structure, a structural unit containing an oxynorbornane lactone structure, or a structural unit containing a butyrolactone structure, Structural units derived from lactone-yl (meth) acrylate, structural units derived from cyano-substituted norbornanelactone-yl (meth) acrylate, structural units derived from oxynorbornanelactone-yl (meth) acrylate, and butyrolactone-3-yl ( More preferred are structural units derived from (meth) acrylates.

  [A] When the polymer has the structural unit (III), the lower limit of the content ratio of the structural unit (III) is preferably 1 mol% with respect to all the structural units constituting the [A] polymer. More preferably, mol% is more preferable, 20 mol% is further more preferable, and 35 mol% is especially preferable. On the other hand, the upper limit of the content ratio of the structural unit (III) is preferably 80 mol%, more preferably 70 mol%, still more preferably 60 mol%, based on all structural units constituting the [A] polymer. 50 mol% is particularly preferred. By making the content rate of structural unit (III) into the said range, [A] polymer can adjust the solubility to a developing solution more appropriately, As a result, the said radiation sensitive resin composition The resolution of the object, the rectangularity of the cross-sectional shape, and the LWR performance can be further improved. Moreover, the adhesiveness of the resist pattern formed from the said radiation sensitive resin composition and a board | substrate can be improved more.

[Structural unit (IV)]
The structural unit (IV) is a structural unit having an alcoholic hydroxyl group (except for those corresponding to the structural unit (I)). [A] The polymer further has the structural unit (IV), so that the solubility in the developer can be adjusted to a more appropriate one. As a result, the resolution of the radiation-sensitive resin composition can be improved. The rectangular shape of the cross-sectional shape and the LWR performance can be improved.

  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.

  [A] When the polymer has a structural unit (IV), the lower limit of the content ratio of the structural unit (IV) in the [A] polymer is 1 for all structural units constituting the [A] polymer. Mol% is preferable, 5 mol% is more preferable, and 8 mol% is more preferable. [A] The upper limit of the content ratio of the structural unit (IV) in the polymer is preferably 40 mol%, more preferably 30 mol%, and more preferably 20 mol%, based on all structural units constituting the [A] polymer. Is more preferable, and 15 mol% is particularly preferable. By making the content rate of structural unit (IV) into the said range, [A] polymer can adjust the solubility to a developing solution more appropriately, As a result, the said radiation sensitive resin composition The resolution of the object, the rectangularity of the cross-sectional shape, and the LWR performance can be further improved.

[Structural unit (V)]
The structural unit (V) is a structural unit containing a phenolic hydroxyl group (except for those corresponding to the structural unit (I)). [A] The polymer further has the structural unit (V), so that the solubility in the developer can be adjusted to a more appropriate level. As a result, the resolution of the radiation-sensitive resin composition can be improved. The rectangular shape of the cross-sectional shape and the LWR performance can be improved. In the case of KrF exposure, EUV exposure or electron beam exposure, the sensitivity of the radiation sensitive resin composition can be increased.

  Examples of the structural unit (V) include a structural unit represented by the following formula (5) (hereinafter also referred to as “structural unit (V-1)”).

In the above formula (5), R ^M1 is a hydrogen atom or a methyl group. L ² is a single bond or a divalent organic group having 1 to 20 carbon atoms. R ^M2 is a monovalent organic group having 1 to 20 carbon atoms. s is an integer of 0-9. When s is 2 or more, the plurality of R ^M2 may be the same or different. r is an integer of 1 to 3. p is an integer of 0-2.

  As the structural unit (V), for example, structural units represented by the following formulas (5-1) to (5-6) (hereinafter also referred to as “structural units (V-1) to (V-6)”) and the like Is mentioned.

  Of these, the structural unit (V-1) is preferable.

  [A] When the polymer has a structural unit (V), the lower limit of the content ratio of the structural unit (V) is preferably 10 mol% with respect to all the structural units constituting the [A] polymer. More preferably, mol% is more preferable, 35 mol% is more preferable, and 45 mol% is especially preferable. As an upper limit of the content rate of a structural unit (V), 80 mol% is preferable with respect to all the structural units which comprise a [A] polymer, 70 mol% is further more preferable, 60 mol% is more preferable, 55 mol% % Is particularly preferred. By setting the content ratio of the structural unit (V) in the above range, the [A] polymer can adjust the solubility in the developer to a more appropriate one, and as a result, the radiation-sensitive resin composition. Resolution, rectangularity of the cross-sectional shape, and LWR performance can be further improved. Moreover, the sensitivity in the case of KrF exposure, EUV exposure, or electron beam exposure of the said radiation sensitive resin composition can be improved more.

[Other structural units]
[A] The polymer may have other structural units in addition to the structural units (I) to (V). Examples of the other structural units include structural units other than the structural unit (I), including a structural unit containing a fluorine atom and a structural unit containing a non-dissociable alicyclic hydrocarbon group. [A] When the polymer has the above-mentioned other structural units, the upper limit of the content ratio of the above-mentioned other structural units is preferably 20 mol% with respect to all the structural units constituting the [A] polymer. Mole% is more preferable.

  [A] The lower limit of the weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) of the polymer is not particularly limited, but is preferably 1,000, more preferably 3,000, and 5,000. More preferably, 7,000 is particularly preferable. On the other hand, the upper limit of the Mw is not particularly limited, but is preferably 40,000, more preferably 20,000, still more preferably 12,000, and particularly preferably 8,000. By setting the Mw in the above range, the resolution, the rectangular shape of the cross-sectional shape, the LWR performance, the depth of focus and the film shrinkage suppression property of the radiation-sensitive resin composition can be further improved and formed. The heat resistance of the resist film can be improved.

  [A] The lower limit of the ratio (Mw / Mn) of Mw to the number average molecular weight (Mn) in terms of polystyrene by GPC of the polymer is usually 1, preferably 1.2, and more preferably 1.4. On the other hand, the upper limit of the Mw / Mn is preferably 5, more preferably 3, more preferably 2, and particularly preferably 1.6. By making said Mw / Mn into the said range, the resolution of the said radiation sensitive resin composition, the rectangularity of a cross-sectional shape, LWR performance, a focal depth, and film | membrane shrinkage | contraction suppression property can be improved more.

  In this specification, Mw and Mn are GPC columns (two "G2000HXL", one "G3000HXL" and one "G4000HXL" manufactured by Tosoh Corporation), a flow rate of 1.0 mL / min, and an elution solvent: tetrahydrofuran. Sample concentration: 1.0% by mass, sample injection amount: 100 μL, column temperature: 40 ° C., using a differential refractometer as a detector and a value measured by GPC using monodisperse polystyrene as a standard .

  [A] The lower limit of the content of the polymer is preferably 40% by mass, more preferably 50% by mass, still more preferably 60% by mass, based on the total solid content of the radiation-sensitive resin composition. Mass% is particularly preferred. On the other hand, the upper limit of the content of the [A] polymer is preferably 99% by mass, more preferably 90% by mass, and still more preferably 80% by mass with respect to the total solid content of the radiation-sensitive resin composition. 75 mass% is particularly preferable.

[[A] Polymer Synthesis Method]
[A] The polymer can be synthesized, for example, by using a radical polymerization initiator or the like and polymerizing monomers giving each structural unit in an appropriate solvent.

  Examples of the radical polymerization initiator include azobisisobutyronitrile (AIBN), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2-cyclopropyl). Azo radical polymerization initiators such as propionitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2′-azobisisobutyrate; benzoyl peroxide, t-butyl hydroper Examples thereof include peroxide radical polymerization initiators such as oxide and cumene hydroperoxide. Of these, AIBN and dimethyl 2,2'-azobisisobutyrate are preferred, and AIBN is more preferred. These radical polymerization initiators can be used singly or in combination of two or more.

Examples of the solvent used for the polymerization include alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane;
Cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, norbornane;
Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumene;
Halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, chlorobenzene;
Saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate and methyl propionate;
Ketones such as acetone, methyl ethyl ketone, 4-methyl-2-pentanone, 2-heptanone;
Ethers such as tetrahydrofuran, dimethoxyethanes, diethoxyethanes;
Examples include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, and 4-methyl-2-pentanol. These solvents can be used alone or in combination of two or more.

  As a minimum of reaction temperature in the above-mentioned polymerization, 40 ° C is preferred, 60 ° C is more preferred, and 70 ° C is still more preferred. On the other hand, the upper limit of the reaction temperature is preferably 150 ° C., more preferably 120 ° C., and still more preferably 100 ° C. As a minimum of reaction time in the above-mentioned polymerization, 30 minutes are preferred, 2 hours are more preferred, and 4 hours are still more preferred. On the other hand, the upper limit of the reaction time is preferably 48 hours, more preferably 24 hours, and even more preferably 10 hours.

  The polymer obtained by the polymerization reaction is preferably recovered by a reprecipitation method. That is, after completion of the polymerization reaction, the polymer is recovered as a powder by introducing the polymerization solution into a reprecipitation solvent. As the reprecipitation solvent, alcohols, alkanes and the like can be used singly or in combination of two or more. In addition to the reprecipitation method, the polymer can be recovered by removing low-molecular components 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 acid-dissociable group of the [A] polymer or the like is dissociated by the generated acid to generate a carboxy group or the like, and the solubility of the [A] polymer in the developer changes. A resist pattern can be formed from the object. The contained form of the [B] acid generator in the radiation-sensitive resin composition may be a low molecular compound form (hereinafter also referred to as “[B] acid generator”) as described below. The form incorporated as a part may be sufficient, and both of these forms may be sufficient.

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

  Examples of the onium salt compounds include sulfonium salts, iodonium salts, tetrahydrothiophenium 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 (7). [B] It is considered that the acid generator has the following structure, and 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. As a result, the resolution, the rectangularity of the cross-sectional shape, and the LWR performance of the radiation sensitive resin composition can be improved.

In the above formula (7), R ²³ 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 ²⁴ is a fluorinated alkanediyl group having 1 to 10 carbon atoms. X ⁺ is a monovalent radiation-sensitive onium cation.

Examples of the monovalent group having an alicyclic structure having 6 or more ring members represented by R ²³ include monocyclic groups such as a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, a cyclodecyl group, and a cyclododecyl group. A cycloalkyl group;
A monocyclic cycloalkenyl group such as a cyclohexenyl group, a cycloheptenyl group, a cyclooctenyl group, a cyclodecenyl group;
A polycyclic cycloalkyl group such as a norbornyl group, an adamantyl group, a tricyclodecyl group, a tetracyclododecyl group;
Examples thereof include polycyclic cycloalkenyl groups such as norbornenyl group and tricyclodecenyl group.

Examples of the monovalent group containing an aliphatic heterocyclic structure having 6 or more ring members represented by R ²³ 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;
Nitrogen atom-containing heterocyclic groups such as azacycloheptyl group and diazabicyclooctane-yl group;
And sulfur atom-containing heterocyclic groups such as a thiacycloheptyl group and a thianorbornyl group.

The lower limit of the ring members of the group represented by R ²³ is preferably 8, 9, and still more preferably 10. On the other hand, the upper limit of the ring members of the group represented by the above R ^23, preferably 15, 13 is more preferable. The the ring members of the group represented by R ²³ in the above range can be adjusted to ones more moderate diffusion length of the aforementioned acids.

Among them, R ²³ is preferably a monovalent group containing an alicyclic structure having 9 or more ring members and a monovalent group containing an aliphatic heterocyclic structure having 9 or more ring members, such as an adamantyl group or hydroxyadamantyl group. Group, norbornanelactone-yl group and 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 ²⁴ include one or more hydrogen atoms of an alkanediyl group having 1 to 10 carbon atoms such as a methanediyl group, an ethanediyl group, and a propanediyl group. And a group in which 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-sensitive onium cation represented by X ⁺ is a cation that decomposes upon irradiation with radiation. In the exposed portion, sulfonic acid is generated from protons generated by the decomposition of the radiation-sensitive onium cation and sulfonate anions. Examples of the monovalent radiation-sensitive onium cation represented by X ⁺ include elements such as S, I, O, N, P, Cl, Br, F, As, Se, Sn, Sb, Te, and Bi. Examples include radiation-sensitive onium cations. Examples of the cation containing S (sulfur) as an element include a sulfonium cation and a tetrahydrothiophenium cation. Examples of cations containing I (iodine) as an element include iodonium cations. Among these, a sulfonium cation represented by the following formula (X-1), a tetrahydrothiophenium cation represented by the following formula (X-2), and an iodonium cation represented by the following formula (X-3) preferable.

In the formula (X-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, a substituted or unsubstituted carbon. number 6-12 aromatic hydrocarbon group, or an -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. When there are a plurality of R ^{a1 to a3} and R ^P and R ^Q , the plurality of R ^a1 may be the same or different, the plurality of R ^a2 may be the same or different, and the plurality of R ^a3 are the same or different. The plurality of ^RPs may be the same or different, and the plurality of ^RQs may be the same or different.

In the above formula (X-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. q is an integer of 0-3.

In the above formula (X-3), R ^c1 and R ^c2 are each independently a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon group having 6 to 6 carbon atoms. 12 aromatic hydrocarbon group, expressed or a -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. When there are a plurality of R ^c1 , R ^c2 , R ^R and R ^S , the plurality of R ^c1s may be the same or different, the plurality of R ^c2s may be the same or different, and the plurality of R ^R may be the same may be different, more structured R ^S may be 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 an n-butyl group. Etc.

Examples of the unsubstituted branched alkyl group represented by R ^{a1 to} R ^a3 , R ^b1 , R ^b2 , R ^c1 and R ^c2 include i-propyl group, i-butyl group, sec-butyl group, t -A butyl group etc. are mentioned.

Examples of the unsubstituted aromatic hydrocarbon group represented by R ^{a1 to} R ^a3 , R ^c1, and R ^c2 include aryl groups such as a phenyl group, a tolyl group, a xylyl group, a mesityl group, and a naphthyl group; a benzyl group, And aralkyl groups such as 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 be substituted for 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. 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 and 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 (X-1), integers of 0 to 2 are preferable, 0 or 1 is more preferable, and 0 is more preferable.

  As k4 in the formula (X-2), an integer of 0 to 2 is preferable, 0 or 1 is more preferable, and 1 is 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 formula (X-3), an integer of 0 to 2 is preferable, 0 or 1 is more preferable, and 0 is more preferable.

As said X ^<+> , the cation represented by the said Formula (X-1) is preferable, and a triphenylsulfonium cation is more preferable.

  Examples of the [B] acid generator represented by the above formula (7) include compounds represented by the following formulas (7-1) to (7-13) (hereinafter referred to as “compounds (7-1) to (7). -13) ")) and the like.

In the above formulas (7-1) to (7-13), X ⁺ has the same meaning as in the above formula (7).

  [B] Among these, as the acid generator, a sulfonium salt and a tetrahydrothiophenium salt are preferable, and the compound (7-1), the compound (7-2), the compound (7-12), and the compound (7-13). ) Is more preferable.

  In the case where the [B] acid generator is incorporated as a part of the polymer, the [B] acid generator includes the above formulas such as structural units represented by the following formula (7-14) ( Those in which the structure 7) is incorporated as part of the polymer are also preferred.

In said formula (7-14), R 'is a hydrogen atom or a methyl group. X ⁺ is synonymous with the above formula (7).

  When the radiation sensitive resin composition contains the [B] acid generator as the [B] acid generator, the lower limit of the content of the [B] acid generator is 100 parts by mass of the [A] polymer. On the other hand, 0.1 mass part is preferable, 1 mass part is more preferable, 3 mass parts is further more preferable, and 7 mass parts is especially preferable. On the other hand, the upper limit of the content of the [B] acid generator is preferably 40 parts by mass, more preferably 30 parts by mass, and even more preferably 25 parts by mass with respect to 100 parts by mass of the [A] polymer. [B] By making content of an acid generator into the said range, the resolution of the said radiation sensitive resin composition, the rectangularity of a cross-sectional shape, and LWR performance can further be improved. The said radiation sensitive resin composition may contain [B] acid generators individually by 1 type or in mixture of 2 or more types.

<[C] solvent>
[C] solvent contained in the radiation sensitive resin composition includes at least [A] polymer, [B] acid generator, [D] acid diffusion controller, [E] polymer added as necessary. [F] There is no particular limitation as long as it can dissolve or disperse the uneven distribution accelerator and other optional components described below, but examples include alcohol solvents, ketone solvents, amide solvents, ether solvents, ester solvents, hydrocarbon solvents. And combinations thereof.

Examples of the alcohol solvent include methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, sec-butanol, tert-butanol, n-pentanol, i-pentanol, and 2-methylbutanol. , Sec-pentanol, tert-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, 3-heptanol, n-octanol, 2-ethyl Hexanol, sec-octanol, n-nonyl alcohol, 2,6-dimethyl-4-heptanol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-hepta Monoalcohol solvents such as decyl alcohol, furfuryl alcohol, phenol, cyclohexanol, methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol, diacetone alcohol;
Ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol, 2 -Polyhydric alcohol solvents such as ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol;
Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethylbutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl Ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol Monomethyl ether, dipropylene glycol monoethyl ether, and polyhydric alcohol partial ether solvents such as dipropylene glycol monopropyl ether.

Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, methyl-n-amyl ketone, ethyl-n-butyl ketone, methyl-n- Chain ketone solvents such as hexyl ketone, di-iso-butyl ketone, trimethylnonanone, acetophenone;
Cyclic ketone solvents such as cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone;
And diketone solvents such as 2,4-pentanedione and acetonylacetone.

  Examples of the amide solvents include N, N′-dimethylimidazolidinone, N-methylformamide, N, N-dimethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N-methylpropionamide, N-methylpyrrolidone and the like can be mentioned.

Examples of the ether solvent include dialiphatic ether solvents such as diethyl ether, dipropyl ether, and dibutyl ether;
Aromatic ring ether solvents such as anisole and diphenyl ether;
Examples thereof include cyclic ether solvents such as tetrahydrofuran and dioxane.

Examples of the ester solvent include monocarboxylic acid ester solvents such as n-butyl acetate and ethyl lactate;
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 n-pentane, i-pentane, n-hexane, i-hexane, n-heptane, i-heptane, 2,2,4-trimethylpentane, n-octane, i-octane, Aliphatic hydrocarbon solvents such as cyclohexane and methylcyclohexane;
Fragrances such as benzene, toluene, xylene, mesitylene, ethylbenzene, trimethylbenzene, methylethylbenzene, n-propylbenzene, i-propylbenzene, diethylbenzene, i-butylbenzene, triethylbenzene, di-i-propylbenzene, n-amylnaphthalene Group hydrocarbon solvents and the like.

  [C] The solvent is preferably an ester solvent, a ketone solvent or a combination thereof, more preferably a polyhydric alcohol partial ether carboxylate solvent, a cyclic ketone solvent or a combination thereof, propylene glycol monomethyl ether acetate, cyclohexanone. Or a combination thereof is more preferable.

<[D] Acid diffusion controller>
[D] The acid diffusion controller is a component that controls the diffusion phenomenon in the resist film of the acid generated from the [B] acid generator by exposure and suppresses an undesirable chemical reaction in the unexposed area. In addition, since the storage stability of the radiation-sensitive resin composition is improved, it is possible to suppress a change in the line width of the resist pattern due to a change in the holding time from exposure to development processing. Thereby, the radiation sensitive resin composition excellent in process stability is obtained. The content of the [D] acid diffusion controller may be a free compound (hereinafter also referred to as “[D] acid diffusion controller”), or may be incorporated as part of the polymer. Both of these forms may be used.

  [D] Examples of the acid diffusion controller include amine compounds, amide group-containing compounds, urea compounds, nitrogen-containing heterocyclic compounds, and the like.

  Examples of the amine compound include mono (cyclo) alkylamines; di (cyclo) alkylamines; tri (cyclo) alkylamines; substituted alkylanilines such as 2,6-diisopropylaniline or derivatives thereof; ethylenediamine, N, N, N ′, N′-tetramethylethylenediamine, tetramethylenediamine, hexamethylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 4,4′-diaminobenzophenone, 4,4′-diamino Diphenylamine, 2,2-bis (4-aminophenyl) propane, 2- (3-aminophenyl) -2- (4-aminophenyl) propane, 2- (4-aminophenyl) -2- (3-hydroxyphenyl) ) Propane, 2- (4-aminophenyl) -2- ( -Hydroxyphenyl) propane, 1,4-bis (1- (4-aminophenyl) -1-methylethyl) benzene, 1,3-bis (1- (4-aminophenyl) -1-methylethyl) benzene, Bis (2-dimethylaminoethyl) ether, bis (2-diethylaminoethyl) ether, 1- (2-hydroxyethyl) -2-imidazolidinone, 2-quinoxalinol, N, N, N ′, N′— Examples include tetrakis (2-hydroxypropyl) ethylenediamine, N, N, N ′, N ″ N ″ -pentamethyldiethylenetriamine, and triethanolamine.

  Examples of the amide group-containing compound include Nt-butoxycarbonyl group-containing amino compounds such as t-butyl-4-hydroxy-1-piperidinecarboxylate, and t-amyl-4-hydroxy-1-piperidinecarboxylate. Nt-amyloxycarbonyl group-containing amino compound, formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methyl Examples include pyrrolidone, N-acetyl-1-adamantylamine, and isocyanuric acid tris (2-hydroxyethyl).

  Examples of the urea compound include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, and tri-n-butylthiourea. Etc.

  Examples of the nitrogen-containing heterocyclic compound include imidazoles; pyridines; piperazines; pyrazine, pyrazole, pyridazine, quinosaline, purine, pyrrolidine, piperidine, 4-hydroxy-N-amyloxycarbonylpiperidine, piperidineethanol, 3-piperidino. -1,2-propanediol; morpholine, 4-methylmorpholine, 1- (4-morpholinyl) ethanol, 4-acetylmorpholine, N- (2-cyclohexylcarbonyloxyethyl) morpholine, 3- (N-morpholino) -1 , 2-propanediol and the like; 1,4-dimethylpiperazine, 1,4-diazabicyclo [2.2.2] octane and the like.

  Among these, amine compounds and amide group-containing compounds are preferred, substituted alkylanilines and Nt-amyloxycarbonyl group-containing compounds are more preferred, t-amyl-4-hydroxy-1-piperidinecarboxylate and 2,6 -Diisopropylaniline is more preferred.

  [D] As the acid diffusion controller, a photodisintegrating base that generates a weak acid by exposure can also be used. The photodegradable base exhibits an acid capturing function by an anion in an unexposed area and functions as a quencher, and captures an acid diffused from the exposed area. On the other hand, in the exposed area, an acid is generated and the anion disappears, so that the acid capturing function is lost. That is, since it functions as a quencher only in the unexposed part, the contrast of the dissociation reaction of the acid dissociable group is improved, and as a result, the resolution and LWR performance of the radiation sensitive resin composition can be further improved. it can. Examples of the photodegradable base include an onium salt compound that loses acid diffusion controllability by being decomposed by exposure. Examples of the onium salt compound include a sulfonium salt compound represented by the following formula (D1) and an iodonium salt compound represented by the following formula (D2).

In the formula (D1) and Formula ^{(D2), R} 25 ~R ²⁹ are each independently a hydrogen atom, an alkyl group, an alkoxy group, hydroxy group, a halogen atom or _-SO 2 -R ^A. R ^A is an alkyl group, a cycloalkyl group, an alkoxy group or an aryl group. Q ^- and ^E - ^{are, OH -, R B -COO -} , R C -SO 2 -N - -R B, R B -SO 3 - is an anion represented by or the following formula (D3). R ^B is a linear or branched alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, an aralkyl group having 7 to 30 carbon atoms. Some or all of the hydrogen atoms of the alkyl group, cycloalkyl group, aryl group and aralkyl group may be substituted. R ^C is a linear or branched alkyl group having 1 to 10 carbon atoms or a cycloalkyl group having 3 to 20 carbon atoms. Some or all of the hydrogen atoms of the alkyl group and cycloalkyl group may be substituted with fluorine atoms. However, when Q ⁻ is R ^B —SO ₃ ^— , a fluorine atom is not bonded to a carbon atom to which SO ₃ ^— is bonded.

In the above formula (D3), R ³⁰ is a linear or branched alkyl group having 1 to 12 carbon atoms, in which part or all of the hydrogen atoms may be substituted with fluorine atoms, or 1 to 12 carbon atoms. These are linear or branched alkoxy groups. u is an integer of 0-2.

The ^R 25 ^{to R 29} in the formula (D1) and (D2), hydrogen atom and _-SO 2 -R ^A is preferred. Moreover, as said ^RA , a cycloalkyl group is preferable and a cyclohexyl group is more preferable.

The alkyl group represented by R ^B, for example a methyl group, an ethyl group, a propyl group, i- propyl group, butyl group, i- butyl, t- butyl group, a part of the hydrogen atoms of these groups or Examples include groups in which all are substituted.

Examples of the cycloalkyl group represented by R ^B include a cyclopentyl group, a cyclohexyl group, a norbornyl group, a tricyclodecanyl group, a tetracyclododecanyl group, an adamantyl group, and a part or all of hydrogen atoms of these groups. Examples include substituted groups.

Examples of the aryl group represented by R ^B include a phenyl group, a naphthyl group, an anthranyl group, and a group in which some or all of the hydrogen atoms of these groups are substituted.

Examples of the aralkyl group represented by R ^B include a benzyl group, a phenylethyl group, a phenylpropyl group, and a group in which some or all of the hydrogen atoms of these groups are substituted.

  As a substituent which the said alkyl group, a cycloalkyl group, an aryl group, and an alkaryl group have, a hydroxyl group, a halogen atom, an alkoxy group, a lactone group, an alkylcarbonyl group etc. are mentioned, for example.

Examples of the alkyl group represented by R ^C include a methyl group, an ethyl group, a propyl group, and a butyl group.

Examples of the cycloalkyl group represented by R ^C include a cyclopentyl group, a cyclohexyl group, a norbornyl group, an adamantyl group, and the like.

  Examples of the photodegradable base include compounds represented by the following formulas.

  Among these, triphenylsulfonium salicylate and triphenylsulfonium camphorsulfonate are preferable, and triphenylsulfonium salicylate is more preferable.

  When the said radiation sensitive resin composition contains the [D] acid diffusion control agent as a [D] acid diffusion control body, as a minimum of content of a [D] acid diffusion control agent, it is the [A] polymer 100. 0.1 parts by mass is preferable with respect to parts by mass, 1 part by mass is more preferable, 1.5 parts by mass is further preferable, and 2 parts by mass is particularly preferable. On the other hand, the upper limit of the content of the [D] acid diffusion controller is preferably 20 parts by mass, more preferably 10 parts by mass, further preferably 7 parts by mass with respect to 100 parts by mass of the polymer [A]. Part by mass is particularly preferred.

<[E] polymer>
The said radiation sensitive resin composition may contain the [E] polymer with a larger fluorine atom content rate (mass%) than a [A] polymer. When the radiation sensitive resin composition contains an [E] polymer, the distribution is unevenly distributed near the resist film surface due to the oil-repellent characteristics of the [E] polymer in the film when the resist film is formed. Therefore, it is possible to suppress the elution of the [B] acid generator, the [D] acid diffusion controller and the like in the immersion medium during the immersion exposure described later. Further, due to the water-repellent characteristics of the [E] 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, since the receding contact angle between the resist film and the immersion medium is increased, it is possible to perform high-speed scanning exposure without leaving water droplets. Thus, when the said radiation sensitive resin composition contains an [E] polymer, the resist film suitable for an immersion exposure method can be formed. The fluorine atom content (% by mass) can be calculated from the structure of the polymer determined by ¹³ C-NMR analysis.

  [E] The polymer is formed by polymerizing one or more monomers containing fluorine atoms in the structure. The monomer containing a fluorine atom in the structure includes a monomer that gives a polymer containing a fluorine atom in the main chain, a monomer that gives a polymer containing a fluorine atom in the side chain, a main chain and a side chain, And a monomer that gives a polymer containing a fluorine atom.

  Examples of monomers that give a polymer containing a fluorine atom in the main chain include α-fluoroacrylate compounds, α-trifluoromethyl acrylate compounds, β-fluoroacrylate compounds, β-trifluoromethyl acrylate compounds, α, β- Examples thereof include a fluoroacrylate compound, an α, β-trifluoromethyl acrylate compound, a compound in which hydrogen at one or more vinyl sites is substituted with a fluorine atom or a trifluoromethyl group.

  As a monomer that gives a polymer containing a fluorine atom in a side chain, for example, a fluorine atom or a fluoroalkyl group or a derivative group thereof is bonded to a site not containing a double bond of an alicyclic olefin compound such as norbornene. An ester compound of acrylic acid or methacrylic acid and a fluoroalkyl group or a derivative group thereof, a fluorine atom or a fluoroalkyl group or a derivative group thereof bonded to a site not containing a double bond of one or more olefins, etc. It is done.

  Examples of the monomer that gives a polymer containing fluorine atoms in the main chain and the side chain include α-fluoroacrylic acid, β-fluoroacrylic acid, α, β-fluoroacrylic acid, α-trifluoromethylacrylic acid, Ester compound of β-trifluoromethylacrylic acid, α, β-trifluoromethylacrylic acid and the like with a fluoroalkyl group or a derivative group thereof, hydrogen in one or more vinyl sites is substituted with a fluorine atom or a trifluoromethyl group A compound in which a fluorine atom or a fluoroalkyl group or a derivative group thereof is bonded to a site not including a double bond of the compound, or a hydrogen atom bonded to a double bond of one or more alicyclic olefin compounds Examples thereof include those substituted with a fluoromethyl group and having a fluoroalkyl group or a derivative group bonded to a site not containing a double bond. In addition, the said alicyclic olefin compound shows the compound in which a part of ring is a double bond.

  [E] Examples of the structural unit of the polymer include a structural unit represented by the following formula (E1) (hereinafter also referred to as “structural unit (EI)”).

In the above formula (E1), R ^E1 represents hydrogen, a fluorine atom, a methyl group, or a trifluoromethyl group. R ^E2 is a divalent linking group. R ^E3 is a linear or branched alkyl group having 1 to 6 carbon atoms containing at least one fluorine atom, a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms, or a derivative thereof. .

Examples of the divalent linking group represented by R ^E2 include a single bond, an oxygen atom, a sulfur atom, a carbonyloxy group, an oxycarbonyl group, an amide group, a sulfonylamide group, and a urethane group.

  Examples of the monomer that gives the structural unit (EI) include trifluoromethyl (meth) acrylic acid ester, 2,2,2-trifluoroethyl (meth) acrylic acid ester, and perfluoroethyl (meth) acrylic acid. Ester, perfluoro n-propyl (meth) acrylate, perfluoro i-propyl (meth) acrylate, perfluoro n-butyl (meth) acrylate, perfluoro i-butyl (meth) acrylate, Perfluoro t-butyl (meth) acrylic acid ester, 2- (1,1,1,3,3,3-hexafluoropropyl) (meth) acrylic acid ester, 1- (2,2,3,3,4 , 4,5,5-octafluoropentyl) (meth) acrylic acid ester, perfluorocyclohexylmethyl (meth) a 1- (2,2,3,3,3-pentafluoropropyl) (meth) acrylic acid ester, 1- (3,3,4,4,5,5,6,6,7,7 , 8,8,9,9,10,10,10-heptadecafluorodecyl) (meth) acrylic acid ester, 1- (5-trifluoromethyl-3,3,4,4,5,6,6, 6-octafluorohexyl) (meth) acrylic acid ester and the like.

  [E] The polymer may have only one type of structural unit (EI) or may have two or more types. As a minimum of the content rate of a structural unit (EI), when all the structural units in a [E] polymer shall be 100 mol%, it is 5 mol% normally, 10 mol% is preferable and 20 mol% is preferable. More preferred is 25 mol%. As an upper limit of the content rate of a structural unit (EI), when all the structural units in a [E] polymer shall be 100 mol%, 50 mol% is preferable, 40 mol% is more preferable, 30 mol% is Further preferred. By setting the content ratio of the structural unit (EI) within the above range, a sufficient receding contact angle can be obtained.

  [E] The polymer preferably has a structural unit containing an acid-dissociable group (hereinafter also referred to as “structural unit (E-II)”) in addition to the structural unit (EI). Examples of the structural unit (E-II) include those similar to the structural unit (II) in the [A] polymer. [E] The polymer may have only one type of structural unit (E-II), or may have two or more types. The lower limit of the content ratio of the structural unit (E-II) is preferably 30 mol%, more preferably 50 mol%, and 65 mol% when all the structural units in the [E] polymer are 100 mol%. Further preferred. The upper limit of the content ratio of the structural unit (E-II) is preferably 95 mol%, more preferably 85 mol%, and 75 mol% when the total structural unit in the [E] polymer is 100 mol%. Further preferred.

  [E] The lower limit of the Mw of the polymer is preferably 1,000, more preferably 2,000, still more preferably 4,000, and particularly preferably 7,000. On the other hand, the upper limit of the Mw of the [E] polymer is preferably 50,000, more preferably 30,000, still more preferably 10,000, and particularly preferably 8,000. [E] By making Mw of a polymer into the said range, sufficient advance contact angle can be obtained and developability can be improved further.

  [E] The lower limit of Mw / Mn of the polymer is usually 1, preferably 1.2, and more preferably 1.4. On the other hand, the upper limit of Mw / Mn of the [E] polymer is usually 5, preferably 3 and more preferably 2.3.

  [E] The polymer can be synthesized, for example, by polymerizing a monomer that gives each predetermined structural unit in a suitable solvent using a radical polymerization initiator.

  When the said radiation sensitive resin composition contains a [E] polymer, as a minimum of content of a [E] polymer, 0.1 mass part is preferable with respect to 100 mass parts of [A] polymers. 1 part by mass is more preferable, 2 parts by mass is further preferable, and 2.5 parts by mass is particularly preferable. On the other hand, as an upper limit of content of [E] polymer, 50 mass parts is preferable, 20 mass parts is more preferable, 10 mass parts is further more preferable, and 5 mass parts is especially preferable. By making content of the [E] polymer in the said radiation sensitive resin composition into the said range, the water repellency and elution suppression property of the resist film surface obtained can be improved more.

[[F] uneven distribution promoter]
[F] The uneven distribution accelerator has an effect of segregating the [E] polymer more efficiently on the resist film surface when the radiation sensitive resin composition contains the [E] polymer. It is. By adding the [F] uneven distribution accelerator to the radiation sensitive resin composition, the amount of the [E] 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 LWR performance, etc., and to perform immersion exposure at a higher speed by high-speed scanning, resulting in a watermark defect or the like. It is possible to improve the hydrophobicity of the resist film surface that suppresses immersion-derived defects. Examples of such [F] uneven distribution promoters include low molecular compounds having a relative dielectric constant of 30 to 200 and a boiling point of 100 ° C. at 1 atm. Specific examples of such compounds include lactone compounds, carbonate compounds, nitrile compounds, and polyhydric alcohols.

  Examples of the lactone compound include butyrolactone, valerolactone, mevalonic lactone, norbornane lactone, and the like. 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.

  When the said radiation sensitive resin composition contains [F] uneven distribution promoter, as a minimum of content of [F] uneven distribution accelerator, the total amount of the polymer in the said radiation sensitive resin composition is 100 mass parts On the other hand, 10 mass parts is preferable, 15 mass parts is more preferable, 20 mass parts is further more preferable, and 25 mass parts is especially preferable. On the other hand, the upper limit of the content of the [F] uneven distribution accelerator is preferably 200 parts by weight, more preferably 100 parts by weight, with respect to 100 parts by weight of the total amount of the polymer in the radiation-sensitive resin composition. Part by mass is more preferable, and 40 parts by mass is particularly preferable.

<Other optional components>
The radiation-sensitive resin composition can contain other optional components in addition to the components [A] to [F]. Examples of the other optional components include surfactants, alicyclic skeleton-containing compounds, and sensitizers. The said radiation sensitive resin composition may contain other arbitrary components individually by 1 type or in mixture of 2 or more types, respectively.

[Surfactant]
The surfactant exhibits the effect of improving the coating property, striation, developability and the like of the radiation sensitive resin composition. 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 are listed. Examples of commercially available surfactants 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. These surfactants can be used singly or in combination of two or more. When the said radiation sensitive resin composition contains surfactant, as an upper limit of content of surfactant, it is 2 mass parts normally with respect to 100 mass parts of [A] polymers.

[Alicyclic skeleton-containing compound]
The alicyclic skeleton-containing compound has an effect of improving the dry etching resistance, pattern shape, adhesion to the substrate, and the like of the resist pattern formed by the radiation-sensitive resin composition.

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 [4.4.0.12,5.17,10] dodecane, 2-hydroxy-9-methoxycarbonyl-5-oxo- 4-oxa-tricyclo [4.2.1.03,7] nonane and the like. These alicyclic skeleton-containing compounds can be used singly or in combination of two or more. When the said radiation sensitive resin composition contains an alicyclic skeleton containing compound, as an upper limit of content of an alicyclic skeleton containing compound, it is 5 mass parts normally with respect to 100 mass parts of [A] polymers. is there.

[Sensitizer]
A sensitizer exhibits the effect | action which increases the production amount of the acid from a [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 can be used alone or in combination of two or more. When the said radiation sensitive resin composition contains a sensitizer, as an upper limit of content of a sensitizer, it is 2 mass parts 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, [C] solvent, [D] acid diffusion controller, [E] polymer, F] It can be prepared by mixing an uneven distribution promoter and other optional components at a predetermined ratio, and preferably filtering through a membrane filter having a pore size of about 0.2 μm. As a minimum of solid content concentration of the radiation sensitive resin composition, 0.1 mass% is preferred, 1 mass% is more preferred, 3 mass% is still more preferred, and 4 mass% is especially preferred. On the other hand, the upper limit of the solid content concentration is preferably 50% by mass, more preferably 25% by mass, further preferably 15% by mass, and particularly preferably 5% by mass.

<Resist pattern formation method>
The resist pattern forming method of the present invention includes a step of forming a resist film (hereinafter also referred to as “resist film forming step”), a step of exposing the resist film (hereinafter also referred to as “exposure step”), and the exposure. A step of developing the resist film (hereinafter also referred to as “development step”), and the resist film is formed of the radiation-sensitive resin composition. Hereinafter, each step will be described.

[Resist film forming step]
In this step, a resist film is formed from the radiation sensitive resin composition. As a substrate on which the resist film is formed, a conventionally known substrate such as a silicon wafer or a wafer coated with aluminum can be used. 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 coating method include spin coating (spin coating), cast coating, and roll coating. As a minimum of the film thickness of the resist film formed, 5 nm is preferable and 10 nm is more preferable. On the other hand, the upper limit of the film thickness is preferably 1,000 nm, and more preferably 500 nm.

  After apply | coating the said radiation sensitive resin composition, you may volatilize the solvent in a coating film by prebaking (PB) as needed. The lower limit of the PB temperature is appropriately selected depending on the composition of the radiation-sensitive resin composition, but is preferably 30 ° C and more preferably 60 ° C. On the other hand, the upper limit of the PB temperature is appropriately selected depending on the composition of the radiation sensitive resin composition, but is preferably 200 ° C., more preferably 120 ° C. The lower limit of the PB time is preferably 5 seconds, and more preferably 10 seconds. On the other hand, the upper limit of the PB time is preferably 600 seconds, and more preferably 200 seconds.

  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, the resist film formed in the resist film forming step is exposed. As this exposure, for example, an isotrench pattern can be formed by performing reduced projection exposure on a desired region through an isoline pattern mask. Moreover, you may perform exposure twice or more with a desired pattern and a mask pattern. When performing exposure twice or more, it is preferable to perform exposure continuously. In the case of performing multiple exposures, for example, a first reduced projection exposure is performed on a desired area via a line and space pattern mask, and then the second is so that the line intersects the exposed portion where the first exposure has been performed. Reduced projection exposure is performed. The first exposure part and the second exposure part are preferably orthogonal. By being orthogonal, it becomes easy to form a perfect circular contact hole pattern in the unexposed area surrounded by the exposed area.

  As the exposure method, immersion exposure is preferred. By using immersion exposure, it is possible to exhibit the effect of change in contact angle before and after development of the resist film formed by the radiation-sensitive resin composition and the effect of suppressing development defects. Examples of the immersion liquid used for exposure 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 decreases 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 layer 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.

  The radiation used for the exposure is appropriately selected according to the type of [B] acid generator. For example, electromagnetic waves such as ultraviolet rays, far ultraviolet rays, extreme ultraviolet rays, visible rays, X-rays and γ rays; Examples thereof include charged particle beams such as α rays. Among these, far ultraviolet rays, extreme ultraviolet rays, and electron beams are preferable, ArF excimer laser light and KrF excimer laser light (wavelength 248 nm) are more preferable, and ArF excimer laser is more preferable. The exposure conditions such as the exposure amount are appropriately selected according to the blending composition of the radiation-sensitive resin composition, the type of additive, and the like. In the pattern formation method, the exposure process may be performed a plurality of times, and the same light source or different light sources may be used for the plurality of exposures, but ArF excimer laser light is used for the first exposure. Is preferred.

  Moreover, it is preferable to perform PEB after exposure. By performing PEB, the dissociation reaction of the acid dissociable group in the radiation sensitive resin composition can proceed smoothly. As a minimum of the above-mentioned PEB temperature, 30 ° C is preferred, 50 ° C is more preferred, and 70 ° C is still more preferred. On the other hand, the upper limit of the PEB temperature is preferably 200 ° C, more preferably 170 ° C, and still more preferably 120 ° C. The lower limit of the PEB time is preferably 5 seconds, and more preferably 10 seconds. On the other hand, the upper limit of the PEB time is preferably 600 seconds, and more preferably 200 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 as a main component. Here, the “main component” is a component having the highest content, for example, a component having a content of 50% by mass or more. 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 and dissolving an exposed area with a predetermined threshold value or more by developing an area with high light irradiation intensity with an alkaline aqueous solution. Can be formed. On the other hand, when a mask pattern is projected onto a resist film by exposure, an exposed portion having a predetermined threshold value or less is dissolved and removed by developing a region having a low light irradiation intensity with a developer containing an organic solvent as a main component. Thus, a negative 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, methyl Diethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide (TMAH), pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, and 1,5-diazabicyclo- [4.3.0] -5 An alkaline aqueous solution in which at least one selected from the group consisting of alkaline compounds such as nonene is dissolved. The concentration of the alkaline aqueous solution is preferably 10% by mass or less. When the concentration of the alkaline aqueous solution exceeds 10% by mass, the unexposed area may be dissolved in the developer. An organic solvent can also be added to the alkaline aqueous solution.

  Examples of the organic solvent contained in the developer containing the organic solvent as a main component include the same organic solvents as those exemplified for the solvent [C]. These organic solvents may be used alone or in combination of two or more. As a minimum of content of the organic solvent contained in the developing solution which has an organic solvent as a main component, 80 mass% is preferred, 90 mass% is more preferred, and 99 mass% is still more preferred. By setting the content to be not less than the above lower limit, good development characteristics can be obtained, and a pattern having more excellent lithography characteristics can be formed. Examples of components other than the organic solvent include water and silicone oil.

  As the developer, a developer containing an organic solvent as a main component is preferable. Since the radiation-sensitive resin composition is excellent in film shrinkage inhibition property, film shrinkage hardly occurs even when PEB is performed after forming a negative resist pattern. Therefore, the resist film formed with the radiation sensitive resin composition can be suitably used for development with a developer containing an organic solvent as a main component.

  An appropriate amount of a surfactant can be added to the developer as necessary. As the surfactant, 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, the formed resist pattern may be washed with a rinse solution. In the case of alkaline development, the rinse liquid is preferably water, and more preferably pure water. In the case of organic solvent development, the rinsing liquid is preferably an alcohol solvent or an ester solvent, more preferably a monovalent alcohol solvent having 6 to 8 carbon atoms, 1-hexanol, 2-hexanol, 2-heptanol and 4 -Methyl-2-pentanol is more preferred.

  As a cleaning method, for example, a method of continuously applying a rinse liquid onto a substrate rotating at a constant speed (rotary coating method), a method of immersing the substrate in a tank filled with the rinse liquid for a predetermined time (dip method) ), A method (spray method) of spraying a rinse liquid on the substrate surface, and the like.

  Examples Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition, each measurement in an Example and a comparative example was performed with the following method.

[Mw and Mn]
Using GPC columns (Toso's "G2000HXL": 2, "G3000HXL": 1 and "G4000HXL": 1), flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran, sample concentration: 1.0 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. Mw / Mn was calculated from the measurement results of Mw and Mn.

[ ¹³ C-NMR analysis]
Using “JNM-ECX400” manufactured by JEOL Ltd., deuterated chloroform was used as a measurement solvent, and the content ratio (mol%) of each structural unit in each polymer was analyzed.

<Synthesis of compounds>
[Synthesis Example 1] (Synthesis of Compound (M-1))
To a 300 mL round bottom flask, 17.2 g (124.3 mmol) of potassium carbonate, 12.2 g (108.8 mmol) of a compound represented by the following formula (m-1) and 100 mL of tetrahydrofuran were added, and stirring was started at room temperature. Thereto was slowly added dropwise a solution prepared by dissolving 20.0 g (103.6 mmol) of the compound represented by the following formula (m-2) in 20 mL of tetrahydrofuran. After completion of dropping, the mixture was stirred at room temperature for 1 hour and then stirred at 50 ° C. for 10 hours. After removing the salt by suction filtration and distilling off the solvent, ethyl acetate was added and the mixture was washed twice with a saturated aqueous ammonium chloride solution. After drying with anhydrous sodium sulfate and distilling off the solvent, 16.2 g (yield 70%) of a compound represented by the following formula (M-1) was obtained by purification by column chromatography.

[Synthesis Examples 2 to 19] (Synthesis of Compounds (M-2) to (M-19))
By appropriately selecting a precursor and performing the same operation as in Synthesis Example 1, compounds represented by the following formulas (M-2) to (M-19) were synthesized.

<Synthesis of [A] polymer and [E] polymer>
The monomers used in the synthesis of each polymer in each example and comparative example are shown below.

[Synthesis Example 20] (Synthesis of Polymer (A-1))
Compound (M′-2) 9.37 g (50 mol%), compound (M′-1) 8.49 g (40 mol%) and compound (M-1) 2.14 g (10 mol%) were converted to 2-butanone. It melt | dissolved in 40g and added AIBN 0.78g (5 mol% with respect to all the monomers) as a radical polymerization initiator, and prepared the monomer solution. Next, a 100 mL three-necked flask containing 20 g of 2-butanone was purged with nitrogen for 30 minutes, and then heated to 80 ° C. with stirring, and the prepared monomer solution was added dropwise over 3 hours using a dropping funnel. The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled with water and cooled to 30 ° C. or lower. The polymerization solution cooled in 400 g of methanol was added, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 80 g of methanol, further filtered and dried at 50 ° C. for 17 hours to synthesize a white powdery polymer (A-1) (15.7 g, yield). 79%). Mw of the polymer (A-1) was 7,300, and Mw / Mn was 1.54. As a result of ¹³ C-NMR analysis, the content ratios of the structural units derived from the compound (M′-2), the compound (M′-1) and the compound (M-1) were 50.1 mol% and 40, respectively. 2 mol% and 9.7 mol%.

[Synthesis Examples 21 to 46] (Synthesis of Polymers (A-2) to (A-27))
Polymers (A-2) to (A-27) were synthesized by performing the same operations as in Synthesis Example 20 using the types and amounts of monomers shown in Table 1 below. The total mass of the monomers used was 20 g.

[Synthesis Example 47] (Synthesis of Polymer (A-28))
Compound (M′-3) 44.55 g (50 mol%), Compound (M′-2) 43.13 g (40 mol%), Compound (M-1) 12.32 g (10 mol%), radical polymerization initiation After dissolving 4.51 g of AIBN (5 mol% based on the total monomers) and 14 g of t-dodecyl mercaptan as an agent in 100 g of propylene glycol monomethyl ether, the reaction temperature was maintained at 70 ° C. in a nitrogen atmosphere. Copolymerized for 16 hours. After completion of the polymerization reaction, the polymer solution was dropped into 1,000 g of n-hexane to solidify and purify the polymer. Next, 150 g of propylene glycol monomethyl ether was added to the polymer again, and then 150 g of methanol, 34 g of triethylamine and 6 g of water were further added, and a hydrolysis reaction was performed for 8 hours while refluxing at the boiling point. After completion of the reaction, the solvent and triethylamine were distilled off under reduced pressure, and the resulting polymer was dissolved in 150 g of acetone, then dropped into 2,000 g of water to solidify, and the resulting white powder was filtered and filtered at 50 ° C. It was made to dry for a period of time to obtain a white powdery polymer (A-28) (62.1 g, yield 70%). Mw of the polymer (A-28) was 7,200, and Mw / Mn was 1.88. As a result of ¹³ C-NMR analysis, the content ratios of the structural units derived from the compound (M′-3), the compound (M′-2), and the compound (M-1) were 50.2 mol% and 40, respectively. 1 mol% and 9.7 mol%.

[Synthesis Example 48] (Synthesis of Polymer (CA-1))
A polymer (CA-1) was synthesized by performing the same operation as in Synthesis Example 20 using the types and amounts of monomers shown in Table 1 below. The total mass of the monomers used was 20 g.

  Table 1 below shows the types and amounts of monomers used in the synthesis of the polymers (A-1) to (A-28) and (CA-1). Table 1 below shows the content (mol%), yield (%), Mw, and Mw / Mn of each structural unit of the polymer. In Table 1, “-” indicates that the corresponding monomer was not used.

[Synthesis Example 49] (Synthesis of Polymer (E-1))
Compound (M′-12) 71.67 g (70 mol%) and compound (M′-13) 28.33 g (30 mol%) were dissolved in 100 g of 2-butanone, and dimethyl 2,2 was used as a radical polymerization initiator. A monomer solution was prepared by dissolving 4.61 g of '-azobisisobutyrate (5 mol% based on the total monomers). Next, a 1,000 mL three-necked flask containing 100 g of 2-butanone was purged with nitrogen for 30 minutes, and then heated to 80 ° C. with stirring, and the prepared monomer solution was added dropwise over 3 hours using a dropping funnel. did. The dripping start was set as the polymerization reaction start time, and the polymerization reaction was carried out for 6 hours. After completion of the polymerization reaction, the polymerization solution was cooled with water and cooled to 30 ° C. or lower. After transferring the polymerization solution to a 2 L separatory funnel, the polymerization solution was uniformly diluted with 150 g of n-hexane, and 600 g of methanol was added and mixed.

Next, 30 g of distilled water was added, and the mixture was further stirred and allowed to stand for 30 minutes. Thereafter, the lower layer was recovered to obtain a propylene glycol monomethyl ether acetate solution containing the polymer (E-1) as a solid content (yield 60%). Mw of the polymer (E-1) was 7,200, and Mw / Mn was 2.00. As a result of ¹³ C-NMR analysis, the content ratios of the structural units derived from the compound (M′-12) and the compound (M′-13) were 71.1 mol% and 28.9 mol%, respectively.

<Preparation of radiation-sensitive resin composition>
[B] acid generator, [C] solvent, [D] acid diffusion controller and [F] uneven distribution accelerator used in the preparation of the radiation sensitive resin compositions of Examples 1 to 31 and Comparative Example 1 below. It is shown below.

[[B] acid generator]
Each structural formula is shown below.
B-1: Triphenylsulfonium 2- (adamantan-1-ylcarbonyloxy) -1,1,3,3,3-pentafluoropropane-1-sulfonate B-2: Triphenylsulfonium norbornane sultone-2-yloxy Carbonyl difluoromethanesulfonate B-3: Triphenylsulfonium 3- (piperidin-1-ylsulfonyl) -1,1,2,2,3,3-hexafluoropropane-1-sulfonate B-4: Triphenylsulfonium adamantane- 1-yloxycarbonyldifluoromethanesulfonate

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

[[D] acid diffusion controller]
Each structural formula is shown below.
D-1: Triphenylsulfonium salicylate D-2: Triphenylsulfonium 10-camphorsulfonate D-3: N- (n-undecan-1-ylcarbonyloxyethyl) morpholine D-4: 2,6-dii -Propylaniline D-5: Tri-n-pentylamine

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

[Example 1] (Preparation of radiation-sensitive resin composition (J-1))
[A] 100 parts by mass of polymer (A-1) as a polymer, [B] 8.5 parts by mass of (B-1) as an acid generator, [C] (C-1) 2, as a solvent 240 parts by mass and (C-2) 960 parts by mass, [D] 2.3 parts by mass of (D-1) acid diffusion control agent, [E] 3 parts by mass of polymer (E-1) as a polymer And [F] 30 mass parts of (F-1) as an uneven distribution promoter were mix | blended, and the radiation sensitive resin composition (J-1) was prepared by filtering with a membrane filter with the hole diameter of 0.2 micrometer.

[Examples 2-31 and Comparative Example 1] (Preparation of radiation-sensitive resin compositions (J-2) to (J-31) and (CJ-1))
Except having used each component of the kind and compounding quantity which are shown in following Table 2, it operated similarly to Example 1 and prepared each radiation sensitive resin composition.

<Formation of resist pattern (1)>
On the surface of a 12-inch silicon wafer, using a spin coater (“CLEAN TRACK ACT12” manufactured by Tokyo Electron), a composition for forming a lower antireflection film (“ARC66” manufactured by Brewer Science) was applied at 205 ° C. Was heated for 60 seconds to form a lower antireflection film having a thickness of 105 nm. On the lower antireflection film, each of the prepared radiation sensitive resin compositions was applied using the spin coater, and PB was performed at 90 ° 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). , Exposed through a 40 nm line and space (1L1S) mask pattern. After the exposure, PEB was performed at 90 ° C. for 60 seconds. Thereafter, alkali development was performed using a 2.38 mass% TMAH aqueous solution as an alkaline developer, washed with water, and dried to form a positive resist pattern. When this resist pattern is formed, the line width formed through a one-to-one line and space mask having a target dimension of 40 nm is defined as an optimum exposure amount. did.

<Formation of resist pattern (2)>
A negative resist pattern was prepared in the same manner as in the above resist pattern formation (1) except that n-butyl acetate was used instead of the TMAH aqueous solution and the organic solvent was developed, and washing with water was not performed. Formed.

<Evaluation>
About the resist pattern formed using each radiation sensitive resin composition, LWR performance, resolution, rectangularity of cross-sectional shape, and depth of focus were evaluated according to the following method. The evaluation results are shown in Table 3 below. A scanning electron microscope (Hitachi High-Technologies “CG-4100”) was used for measuring the resist pattern.

[LWR performance]
The resist pattern was observed from above the pattern using the scanning electron microscope. A total of 50 line widths were measured at arbitrary points, and a 3-sigma value was obtained from the distribution of the measured values, and this was defined as LWR performance (nm). The LWR performance indicates that the smaller the value, the smaller the backlash of the line. The LWR performance can be evaluated as “good” when it is 3.6 nm or less, and “bad” when it exceeds 3.6 nm.

[Resolution]
The dimension of the minimum resist pattern that can be resolved at the optimum exposure dose is measured, and the measurement result is defined as resolution (nm). The resolution indicates that the smaller the value, the better. The resolution can be evaluated as “good” when it is 34 nm or less, and “bad” when it exceeds 34 nm.

[Rectangularity of cross-sectional shape]
The cross-sectional shape of the resist pattern resolved at the optimum exposure dose was observed, and the line width Lb in the middle of the resist pattern in the height direction and the line width La at the top of the film were measured. The rectangularity of the cross-sectional shape can be evaluated as “good” when 0.9 ≦ La / Lb ≦ 1.1, and “bad” when outside the above range.

[Depth of focus]
In the resist pattern resolved at the optimum exposure amount, the depth when the focus is changed in the depth direction is observed, and the depth within which the pattern dimension is 90% or more and 110% or less of the reference without any bridge or residue. The degree of directional margin was measured, and the measurement result was defined as the depth of focus (nm). It shows that the larger the value of the depth of focus, the smaller the variation of the dimension of the pattern obtained when the position of the focal point varies, and the higher the yield at the time of device fabrication. The depth of focus can be evaluated as “good” when it is 45 nm or more, and “bad” when it is less than 45 nm.

  From the results in Table 3, it was shown that the radiation-sensitive resin compositions of the examples were excellent in LWR performance, resolution, rectangularity of the cross-sectional shape, and depth of focus. On the other hand, it was shown that the radiation sensitive resin composition of the comparative example was inferior in all of the above performances to the examples.

[Membrane shrinkage by PEB]
On the surface of a 12-inch silicon wafer, using a spin coater (“CLEAN TRACK ACT12” manufactured by Tokyo Electron), a composition for forming a lower antireflection film (“ARC66” manufactured by Brewer Science) was applied at 205 ° C. Was heated for 60 seconds to form a lower antireflection film having a thickness of 105 nm. On the lower antireflection film, each of the prepared radiation sensitive resin compositions was applied using the spin coater, and PB was performed at 90 ° 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 exposed to the whole surface at 70 mJ using an ArF excimer laser immersion exposure apparatus (“NSR-S610C” manufactured by NIKON), and the film thickness was measured to obtain the film thickness A. Then, after implementing PEB for 60 seconds at 90 degreeC, the film thickness measurement was implemented again and the film thickness B was calculated | required. At this time, 100 × (A−B) / A (%) was obtained and used as the film shrinkage rate (%) by PEB. These results are shown in Table 4 below. The smaller the value of the film shrinkage rate by PEB, the better. The film shrinkage rate by PEB can be evaluated as “good” when it is 20% or less, and “bad” when it exceeds 20%.

  From the results in Table 4, it was shown that the radiation-sensitive resin compositions of the examples had a small film shrinkage rate due to PEB, that is, excellent film shrinkage inhibition properties. On the other hand, it was shown that the radiation-sensitive resin composition of the comparative example has a greater film shrinkage inhibition property than that of the example, that is, inferior to the film shrinkage inhibition property.

[Example 32] (Preparation of radiation-sensitive resin composition (J-32))
[A] 100 parts by mass of (A-1) as a polymer, [B] 20 parts by mass of (B-1) as an acid generator, [C] 4,280 parts by mass of (C-1) as a solvent, and (C-2) 1,830 parts by mass and [D] 3.6 parts by mass of (D-1) as an acid diffusion controller are mixed and filtered through a membrane filter having a pore size of 0.2 μm to provide a radiation sensitive resin. A composition (J-32) was prepared.

[Examples 33 to 35 and Comparative Example 2] (Preparation of radiation-sensitive resin compositions (J-33) to (J-35) and (CJ-2))
Each radiation-sensitive resin composition was prepared in the same manner as in Example 32 except that the components of the types and blending amounts shown in Table 5 below were used.

<Formation of resist pattern (3)>
Using a spin coater (“CLEAN TRACK ACT8” manufactured by Tokyo Electron Co., Ltd.) on the surface of an 8-inch silicon wafer, each radiation-sensitive resin composition shown in Table 5 was applied, and PB was performed at 90 ° C. for 60 seconds. It was. Then, it cooled at 23 degreeC for 30 second, and formed the resist film with a film thickness of 50 nm. Next, the resist film was irradiated with an electron beam by using a simple electron beam drawing apparatus (“HL800D” manufactured by Hitachi, Ltd., output: 50 KeV, current density: 5.0 A / cm ² ). After irradiation, PEB was performed at 120 ° C. for 60 seconds. Thereafter, development was performed at 23 ° C. for 30 seconds using a 2.38 mass% TMAH aqueous solution as an alkali developer, washed with water, and dried to form a positive resist pattern.

<Formation of resist pattern (4)>
A negative resist pattern was prepared in the same manner as in the above resist pattern formation (3) except that n-butyl acetate was used instead of the TMAH aqueous solution and the organic solvent was developed. Formed.

<Evaluation>
About the resist pattern formed using each radiation sensitive resin composition, LWR performance was evaluated in accordance with the following method, and resolution, rectangularity of a cross-sectional shape, and depth of focus were evaluated in the same manner as in Examples 1-31. . These results are shown in Table 6 below.

[LWR performance]
The evaluation was performed in the same manner as the evaluation of the LWR performance described above, except that the criteria for determining the LWR performance were changed as follows. The LWR performance can be evaluated as “good” when it is 5 nm or less and “bad” when it exceeds 5 nm.

  From the results of Table 6, it was shown that the radiation-sensitive resin compositions of the examples were excellent in LWR performance, resolution, rectangularity of the cross-sectional shape, and depth of focus. On the other hand, it was shown that the radiation sensitive resin composition of the comparative example was inferior in all of the above performances to the examples.

  According to the radiation-sensitive resin composition and resist pattern forming method of the present invention, a resist pattern that exhibits excellent depth of focus and film shrinkage suppression, high resolution, low LWR, and excellent cross-sectional rectangularity. Can be formed. Accordingly, these can be suitably used for manufacturing semiconductor devices that are expected to be further miniaturized in the future.

Claims (7)

A first polymer having a first structural unit represented by the following formula (1):
A radiation-sensitive resin composition comprising a radiation-sensitive acid generator and a solvent.

(In formula (1), X is a monovalent group represented by the following formula (1-a) or (1-b). R ¹ and R ² are each independently a hydrogen atom or methyl. R ³ is a hydrogen atom or a monovalent organic group having 1 to 30 carbon atoms, and n is an integer of 1 to 5.)

(In Formula (1-a), R ⁴ and R ⁵ are each independently substituted with —CN, —NO ₂ , a monovalent fluorinated hydrocarbon group having 1 to 30 carbon atoms, or a polar group. a monovalent monovalent group represented by a hydrocarbon group or a -Y-Z C1-30 .Y is, -CO -, - COO -, - SO 2 - or _-SO 2 O-in carbon some .Z is .R ⁶ is a monovalent organic group having 1 to 30 carbon atoms, which is adjacent to the hydrogen atom, a fluorine atom, the carbon atom to which -NO _2, or ^R 4, ^{R 5} and ^{R 6} are bonded It is a C1-C30 monovalent organic group containing an atom, a nitrogen atom or a sulfur atom, and two or more of R ⁴ , R ⁵ and R ⁶ are combined with each other and the number of ring members together with the carbon atom to which they are bonded. It may form a ring structure of 3 to 20. When Y is plural, the plural Ys may be the same or different. A plurality of cases, the plurality of Z in different may. * Also identical, indicating the site that binds to a portion other than the X of the first structural unit.
In formula (1-b), R ⁴ and R ⁵ each independently represent —CN, —NO ₂ , carbon having 1 to 30 carbon atoms substituted with a monovalent fluorinated hydrocarbon group or polar group. It is a monovalent hydrocarbon group represented by the formula 1-30, or a monovalent group represented by -YZ. Y is, -CO -, - COO -, - SO 2 - or _-SO 2 is O-. Z is a monovalent organic group having 1 to 30 carbon atoms. R ⁴ and R ⁵ may be combined with each other to form a ring structure having 3 to 20 ring members together with the nitrogen atom to which they are bonded. When Y is plural, the plural Ys may be the same or different. When there are a plurality of Zs, the plurality of Zs may be the same or different. * Indicates a site that binds to a portion other than X of the first structural unit. )   2. The radiation-sensitive resin composition according to claim 1, wherein the content ratio of the first structural unit with respect to all the structural units constituting the first polymer is 1 mol% or more and 30 mol% or less.   The radiation sensitive resin composition according to claim 1 or 2, wherein the first polymer further has a second structural unit containing an acid dissociable group.   4. The radiation-sensitive resin composition according to claim 1, wherein the first polymer further has a third structural unit including a lactone structure, a cyclic carbonate structure, a sultone structure, or a combination thereof.   N in said Formula (1) is 1, The radiation sensitive resin composition of any one of Claims 1-4. 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.   The resist pattern forming method according to claim 6, wherein the developer used in the developing step contains an organic solvent as a main component.