JP5728884B2 - Radiation-sensitive resin composition and method for producing the same - Google Patents

Description

  The present invention relates to a chemically amplified resist composition, particularly a radiation-sensitive resin composition suitably used as a resist composition for immersion exposure, and a method for producing the radiation-sensitive resin composition.

  In the field of microfabrication represented by the manufacture of integrated circuit elements, conventionally, a resist film is formed on a substrate with a resin composition containing a polymer having an acid dissociable group, and the resist film is formed on the resist film via a mask pattern. A fine resist pattern is formed by irradiating a short-wavelength radiation such as an excimer laser for exposure, and removing an exposed portion with an alkaline developer. Under the present circumstances, the chemical amplification type resist which contained the radiation sensitive acid generator which generate | occur | produces an acid by irradiation in a resin composition, and improved the sensitivity by the effect | action of the acid is utilized.

  In such a chemically amplified resist, for example, as a method for forming a finer resist pattern having a line width of about 45 nm, the use of an immersion exposure method (liquid immersion lithography) is expanding. In this method, the exposure optical path space (between the lens and the resist film) is filled with an immersion medium having a refractive index (n) larger than that of air or an inert gas, such as pure water or a fluorine-based inert liquid. The exposure is performed in the state. Therefore, even when the numerical aperture (NA) of the lens is increased, there is an advantage that the depth of focus is hardly lowered and high resolution can be obtained.

  In the immersion exposure method, it is required to prevent device contamination by suppressing the elution of acid generators from the resist film, and to increase the scanning exposure speed by improving the water drainage of the film surface. Publication No. 2007/116664 proposes a resin composition containing a fluorine-containing polymer having high hydrophobicity.

  However, simply increasing the hydrophobicity of the resist film reduces the surface wettability of the developer and rinse solution, resulting in insufficient removal of the development residue, and development defects such as blobs may occur. . For the purpose of suppressing such development defects, Japanese Patent Application Laid-Open No. 2010-032994 discloses hydrophobicity during immersion exposure, but hydrophobicity due to hydrolysis of a base-dissociable group during alkaline development. Fluorine-containing polymers have been proposed in which the lowering is achieved.

  A fluoropolymer having such a base-dissociable group is preferably designed to have a high reactivity with an alkali such as an alkali developer because the development time can be shortened and the hydrolysis proceeds in a shorter time. ing. In addition, at present, when the miniaturization of the resist pattern is progressing to a level of 90 nm or less, a basic compound is used as an acid diffusion control agent for the purpose of improving the pattern shape and reducing the variation in the line width. Increasingly added. Therefore, the hydrolysis proceeds during long-term storage, and particles are easily generated in the composition. In addition, the radiation sensitivity of the composition, the receding contact angle of the resist film obtained from the composition, etc. There is an inconvenience that the characteristics are easily changed.

International Publication No. 2007/116664 JP 2010-032994 A

  The present invention has been made in view of these disadvantages, and its purpose is excellent in storage stability, generation of particles in the liquid is suppressed even during long-term storage, radiation sensitivity and receding contact of the resulting resist film. An object of the present invention is to provide a radiation-sensitive resin composition having a small variation with time in characteristics such as corners.

  As a result of intensive studies to achieve the above-mentioned object, the present inventors have made the radiation-sensitive resin composition at the time of storage by making the content of the metal contained in the radiation-sensitive resin composition below a certain value. As a result, it was found that fluctuations with time of the above characteristics can be suppressed, and the present invention has been completed.

The invention made to solve the above problems is
[A] containing a fluoropolymer having a structural unit (f) containing a base dissociable group,
A radiation-sensitive resin composition having a total metal content of 30 mass ppb or less.

  The radiation-sensitive resin composition of the present invention contains [A] a fluoropolymer, and is excellent in storage stability when the total content of metals is 30 mass ppb or less. That is, the generation of particles during storage in the composition is suppressed, and the radiation sensitivity of the composition and the characteristics such as the receding contact angle during exposure of the resist film surface to be obtained vary substantially even after long-term storage. do not do.

  As described above, the reason why the storage stability is improved by setting the total content of metals in the radiation-sensitive resin composition to 30 mass ppb or less is not necessarily clear. It is considered that the hydrolysis reaction is suppressed, and the generation of particles caused by the substance generated by the hydrolysis and the like and the fluctuation of the above characteristics are suppressed. It is also considered that the generation of particles in the liquid that occurs with metal as a nucleus is suppressed.

  The metal is preferably sodium, magnesium or iron, and each content of sodium, magnesium and iron is preferably 3 mass ppb or less. Of the metals in the radiation-sensitive resin composition, sodium, magnesium and iron have been found to have a large degree of influence on storage stability. Therefore, in order to further improve the storage stability of the radiation-sensitive resin composition, it is desirable that the contents of these metal species are all within the above range.

  The base dissociable group of the structural unit (f) may have a fluorine atom. A base dissociable group having a fluorine atom has a high dissociation property due to the electron withdrawing property of the fluorine atom. Since the radiation sensitive resin composition containing such a fluoropolymer generally tends to cause characteristic fluctuations during storage, the effect of setting the metal content within a specific range is particularly great.

  The base dissociable group may be an aromatic hydrocarbon group having a fluorine atom. When an aromatic hydrocarbon group having a fluorine atom is used as a base dissociable group, the dissociation property is further increased, and therefore, characteristic variation during storage tends to easily occur. Therefore, the effect of setting the metal content within a specific range is further increased.

（式（１）中、Ｒは水素原子、フッ素原子又は炭素数１〜４の１価の鎖状炭化水素基であり、この炭素数１〜４の１価の鎖状炭化水素基が少なくとも１個のハロゲン原子を有していてもよい。Ｅは単結合又は（ｎ＋１）価の連結基である。Ｒｆはフッ素原子を有していてもよい１価の鎖状炭化水素基又は１価の芳香族炭化水素基である。ｎは１〜３の整数である。ｎが２又は３の場合、Ｒｆはそれぞれ独立して上記定義を有する。） [A] The structural unit (f) in the fluoropolymer may be represented by the following formula (1).

(In Formula (1), R is a hydrogen atom, a fluorine atom, or a monovalent chain hydrocarbon group having 1 to 4 carbon atoms, and the monovalent chain hydrocarbon group having 1 to 4 carbon atoms is at least 1; E may be a single bond or a (n + 1) -valent linking group, Rf may be a monovalent chain hydrocarbon group that may have a fluorine atom, or a monovalent An aromatic hydrocarbon group, n is an integer of 1 to 3. When n is 2 or 3, each Rf independently has the above definition.

  When the structural unit (f) in the [A] fluoropolymer has the specific structure, the [A] fluoropolymer can be easily synthesized.

（式（１−１）中、Ｒ及びＲｆの定義は上記式（１）と同じである。Ｒ^ａは置換基を有していてもよい２価の鎖状の有機基又は芳香族炭化水素基である。Ｘは少なくとも１個のフッ素原子を有する２価の炭化水素基である。）

（式（１−２）中、Ｒ及びＲｆの定義は上記式（１）と同じである。Ｒ^ａは置換基を有していてもよい２価の鎖状の有機基又は芳香族炭化水素基である。）

（式（１−３）中、Ｒの定義は上記式（１）と同じである。Ｒ^０は１価の芳香族炭化水素基である。この芳香族炭化水素基の水素原子の一部又は全部が置換基によって置換されていてもよい。Ｒ^２１はメチレン基、−ＣＨ（ＣＨ_３）−、−Ｃ（ＣＨ_３）_２−、−ＣＨ_２ＣＨ_２−又は酸素原子である。Ｒ^２２は水素原子又は置換基である。）

（式（１−４）中、Ｒ’は少なくとも１個のフッ素原子を有する炭素数１〜４の１価の鎖状炭化水素基である。Ｒｆの定義は上記式（１）と同じである。） The said Formula (1) is good in it being at least 1 sort (s) chosen from the structural unit group respectively represented by following formula (1-1), (1-2), (1-3) and (1-4). .

(In the formula (1-1), the definitions of R and Rf are the same as those in the above formula (1). R ^a is ^a divalent chain organic group or aromatic hydrocarbon which may have ^a substituent. X is a divalent hydrocarbon group having at least one fluorine atom.)

(In the formula (1-2), the definitions of R and Rf are the same as those in the above formula (1). R ^a is ^a divalent chain-like organic group or aromatic hydrocarbon which may have ^a substituent. Group.)

(In formula (1-3), the definition of R is the same as that in the above formula (1). R ⁰ is a monovalent aromatic hydrocarbon group. A part of hydrogen atoms of this aromatic hydrocarbon group or all of which may be substituted by a substituent ^{.R 21} is methylene _{group, -CH (CH 3) -,} - C (CH 3) 2 -, - CH 2 CH 2 - or ^{.R 22} is an oxygen atom It is a hydrogen atom or a substituent.)

(In the formula (1-4), R ′ is a monovalent chain hydrocarbon group having 1 to 4 carbon atoms having at least one fluorine atom. The definition of Rf is the same as in the above formula (1). .)

  [A] When the structural unit (I) in the fluoropolymer has a specific structure selected from the above structural unit group, the monomer giving these structural units has high polymerizability, and [A] in the fluoropolymer The content of these structural units can be increased. Therefore, the magnitude of the receding contact angle on the resist film surface formed from the radiation-sensitive resin composition and the degree of reduction of the receding contact angle due to alkali development can be increased.

  [A] It is preferable that the fluoropolymer further has a structural unit (p) containing an acid dissociable group. [A] When the fluoropolymer further has a structural unit containing an acid-dissociable group, the shape of the resist pattern formed from the radiation-sensitive resin composition after alkali development can be improved.

（式（４）中、Ｒは水素原子、フッ素原子又は炭素数１〜４の１価の鎖状炭化水素基であり、この炭素数１〜４の１価の鎖状炭化水素基が少なくとも１個のハロゲン原子を有していてもよい。Ｙは下記式（Ｙ−１）で表される基である。）

（式（Ｙ−１）中、Ｒ^ｐ１は炭素数１〜４の１価の鎖状炭化水素基又は炭素数４〜２０の１価の脂肪族環状炭化水素基である。Ｒ^ｐ２及びＲ^ｐ３はそれぞれ独立して炭素数１〜４の１価の鎖状炭化水素基又は炭素数４〜２０の１価の脂肪族環状炭化水素基であるか、又はＲ^ｐ２及びＲ^ｐ３が互いに結合して、それぞれが結合している炭素原子と共に炭素数４〜２０の２価の脂肪族環状炭化水素基を形成する。） [A] The structural unit (p) in the fluoropolymer is preferably a structural unit (IV) represented by the following formula (4).

(In Formula (4), R is a hydrogen atom, a fluorine atom, or a monovalent chain hydrocarbon group having 1 to 4 carbon atoms, and the monovalent chain hydrocarbon group having 1 to 4 carbon atoms is at least 1; (Y may be a group represented by the following formula (Y-1)).

(In the formula (Y-1), R ^p1 is a monovalent chain hydrocarbon group having 1 to 4 carbon atoms or a monovalent aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms. R ^p2 and R ^p3 Are each independently a monovalent chain hydrocarbon group having 1 to 4 carbon atoms or a monovalent aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms, or R ^p2 and R ^p3 are bonded to each other. , Together with the carbon atoms to which each is bonded, a divalent aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms is formed.)

  [A] When the structural unit (p) of the fluoropolymer has the specific structure, a resist pattern formed from the radiation-sensitive resin composition due to the high dissociation ease of the acid dissociable group The shape after alkali development can be further improved.

Moreover, another invention made in order to solve the said subject is:
[A] A method for producing the radiation-sensitive resin composition, comprising a step of filtering a solution containing a fluoropolymer with a nylon filter or an ion exchange filter. According to the production method, the content of the metal contained in the radiation-sensitive resin composition can be easily within the specific range, and the radiation-sensitive resin composition having excellent storage stability can be produced at a low production cost. It can be manufactured easily and reliably while suppressing the rise.

  In the present specification, the term “hydrocarbon group” includes a chain hydrocarbon group, an aliphatic cyclic hydrocarbon group, and an aromatic hydrocarbon group. This “hydrocarbon group” may be a saturated hydrocarbon group or an unsaturated hydrocarbon group.

  In addition, the “chain hydrocarbon group” means a hydrocarbon group that does not include a cyclic structure in the main chain and is composed only of a chain structure, and includes both a linear hydrocarbon group and a branched hydrocarbon group. Shall be included. The “aliphatic cyclic hydrocarbon group” means a hydrocarbon group that includes only an aliphatic cyclic hydrocarbon structure as a ring structure and does not include an aromatic ring structure. However, it is not necessary to be constituted only by the structure of the aliphatic cyclic hydrocarbon, and a part thereof may include a chain structure. The “aromatic hydrocarbon group” means a hydrocarbon group containing an aromatic ring structure as a ring structure. However, it is not necessary to be composed only of an aromatic ring structure, and a part thereof may include a chain structure or an aliphatic cyclic hydrocarbon structure.

  As described above, the radiation-sensitive resin composition of the present invention contains the [A] fluoropolymer having a structural unit containing a base-dissociable group, and the total content of metals is a certain value or less. And excellent storage stability. That is, the radiation-sensitive resin composition suppresses the generation of particles even during long-term storage, and changes with time in characteristics such as radiation sensitivity and the receding contact angle of the resulting resist film are small. Moreover, according to the manufacturing method of the radiation sensitive resin composition of this invention, it can manufacture easily and reliably, suppressing the raise of manufacturing cost.

  Hereinafter, embodiments of the present invention will be described in detail.

<Radiation sensitive resin composition>
The radiation-sensitive resin composition of the present invention contains [A] a fluorine-containing polymer, and, as a preferred component, [B] a polymer having a smaller fluorine atom content than the [A] fluorine-containing polymer described later, [C] A radiation sensitive acid generator, [D] acid diffusion controller, and [E] solvent may be contained, and other optional components may be contained unless the effects of the present invention are impaired. The total metal content of the radiation-sensitive resin composition of the present invention is 30 mass ppb or less. Hereinafter, each component will be described in detail.

<[A] Fluoropolymer>
The [A] fluoropolymer in the present invention is a polymer having a structural unit (f) containing a base dissociable group and having a fluorine atom. [A] The fluoropolymer is not particularly limited as long as it has a fluorine atom in the polymer. The structural unit (f) may have a fluorine atom, or may be contained in another structural unit other than the structural unit (f). [A] The fluorine-containing polymer may have a fluorine atom in the main chain or in a side chain. [A] Since the fluorine-containing polymer has fluorine atoms, the resist coating surface exhibits a high dynamic contact angle due to its high hydrophobicity. Therefore, according to the radiation sensitive resin composition, the [A] fluoropolymer is unevenly distributed on the surface of the coating, and it is possible to suppress elution of the acid generator and the like from the coating and to impart high drainage characteristics to the coating surface. . [A] The fluorine-containing polymer has a structural unit (f) containing a base dissociable group and dissociates by hydrolysis in alkali development to produce a hydrophilic group. descend. As a result, the wettability of the coating surface with respect to the developer and the rinsing liquid is greatly improved in the alkali developing step, so that it is possible to suppress development defects of the resist film caused by the low cleaning efficiency with the rinsing liquid.

[Structural unit (f)]
The structural unit (f) contains a base dissociable group. The base dissociable group means a group that dissociates upon contact with a base, for example, a group that replaces a hydrogen atom in a polar functional group such as a hydroxyl group or a carboxyl group, and in the presence of an alkali (for example, 23 It means a group that dissociates at a temperature of 2.38 mass% tetramethylammonium hydroxyside (° C.). The base dissociable group in the structural unit (f) is not particularly limited as long as it is a group having such properties. Specific examples include groups represented by the following formulas (fa) to (fc). Can be mentioned.

In the above formulas (fa) and (fb), ^Rb is a hydrocarbon group which may have a fluorine atom.
In the above formula (fc), R ^c is a monovalent aromatic hydrocarbon group which may have a substituent. R ^d is a monovalent aliphatic hydrocarbon group or aromatic hydrocarbon group which may be substituted with a halogen atom.

  Among the above base dissociable groups, those having a fluorine atom are preferred. When the base-dissociable group has a fluorine atom having a high electron-withdrawing property, the base-dissociable group is easily dissociated, so that the benefit of the storage stability improving effect of the present invention is increased. Specific examples of the base-dissociable group having a fluorine atom include a chain hydrocarbon group having a fluorine atom, an aliphatic cyclic hydrocarbon group having a fluorine atom, and an aromatic hydrocarbon group having a fluorine atom. Among these, an aromatic hydrocarbon group having a fluorine atom is particularly preferable from the viewpoint of further increasing the ease of dissociation as a base dissociable group.

  Preferable examples of the structural unit (f) include the structural unit (I) represented by the above formula (1). When the [A] fluoropolymer has the structural unit (I), the [A] fluoropolymer can be easily synthesized by using a monomer that gives the structural unit (I).

  In the above formula (1), R is a hydrogen atom, a fluorine atom or a monovalent chain hydrocarbon group having 1 to 4 carbon atoms, and the monovalent chain hydrocarbon group having 1 to 4 carbon atoms is at least 1 May have one halogen atom. E is a single bond or a divalent linking group. Rf is a monovalent chain hydrocarbon group or monovalent aromatic hydrocarbon group which may have a fluorine atom.

  Examples of the monovalent chain hydrocarbon group having 1 to 4 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, t -A butyl group is mentioned.

  Examples of the halogen atom in the monovalent chain hydrocarbon group having 1 to 4 carbon atoms having at least one halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Specific examples of the C1-C4 monovalent chain hydrocarbon group having at least one halogen atom include, for example, a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a fluoroethyl group, and trifluoro Fluoroalkyl groups such as ethyl group, pentafluoroethyl group, trifluoropropyl group, hexafluoropropyl group, heptafluoropropyl group, trifluorobutyl group, nonafluorobutyl group; chloromethyl group, trichloromethyl group, trichloroethyl group, Chloroalkyl groups such as pentachloroethyl group, hexachloropropyl group, heptachloropropyl group, nonachlorobutyl group; bromoalkyl groups such as tribromomethyl group, pentabromoethyl group, heptabromopropyl group, nonabromobutyl group; triiodomethyl Group, pentayo Doechiru group, hepta-iodo propyl group, and iodo group such Nonaburomobuchiru group.

  E in the above formula (1) is a single bond or a divalent to tetravalent linking group.

Specific examples of the divalent to tetravalent linking group represented by E include a hydrocarbon group in which 2 to 4 hydrogen atoms have been removed from the following hydrocarbon compound.
Linear or branched chain saturated hydrocarbons such as methane, ethane, propane, butane, pentane, hexane, octane, decane, hexadecane and icosane;
Linear or branched chain unsaturated hydrocarbons such as ethylene, propylene, butene, pentene, hexene, octene, decene, tetradecene, propyne, hexyne, butadiene, hexadiene, decadiene, hexadiyne, decadiine;
Monocyclic saturated hydrocarbons such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, cyclooctane, cyclodecane;
Monocyclic unsaturated hydrocarbons such as cyclobutene, cyclopentene, cyclohexene, cyclooctene, cyclodecene, cyclododecine, cyclopentadiene, cyclohexadiene, cyclodecadiene, cyclodecadiyne;
Bicyclo [2.2.1] heptane, bicyclo [2.2.2] octane, tricyclo [5.2.1 ^2,6 ] decane, tricyclo [3.3.1.1 ^3,7 ] decane, tetracyclo [ 6.2.1.1 ^3,6 . 0 ^2,7 ] polycyclic saturated hydrocarbons such as dodecane and adamantane;
Bicyclo [2.2.1] heptene, bicyclo [2.2.2] octene, tricyclo [5.2.1 ^2,6 ] decene, tricyclo [3.3.1.1 ^3,7 ] decene, tetracyclo [ 6.2.1.1 ^3,6 . 0 ^2,7 ] dodecene and other polycyclic unsaturated hydrocarbons;
Aromatic hydrocarbons such as benzene, naphthalene, anthracene, phenanthrene, pyrene, toluene, xylene, trimethylbenzene, ethylbenzene, cumene, methylnaphthalene, dimethylnaphthalene, durene.
Among these, linear and branched chain saturated hydrocarbons having 1 to 8 carbon atoms, aliphatic cyclic hydrocarbons having 5 to 12 carbon atoms, chain unsaturated hydrocarbons having 2 to 6 carbon atoms, and carbon numbers 6 A hydrocarbon group obtained by removing 2 to 4 hydrogen atoms from ˜15 aromatic hydrocarbons is preferred.

  The linking group E may contain an ether group, a carbonyl group, an ester group, an amide group, a urethane group, a urea group, a carbonate group, an imino group, a thioether group, etc. at the terminal or non-terminal position. A heterocycle containing the group may be formed.

The linking group E may have a substituent. Examples of such ^{substituents, -R P1, -R P2 -O-} R P1, -R P2 -CO-R P1, -R P2 -CO-OR P1, -R P2 -O-CO-R P1, -R ^{P2 -OH,} -R ^{P2 -CN,} or ^-R P2 -COOH ^{(R P1} is a monovalent chain saturated hydrocarbon group having 1 to 10 carbon atoms, a monovalent aliphatic cyclic having 3 to 20 carbon atoms a saturated hydrocarbon group or a monovalent aromatic hydrocarbon group having 6 to 30 carbon atoms, partially or entirely single bond good .R ^P2 be substituted by fluorine atoms hydrogen atoms of these groups , A divalent chain saturated hydrocarbon group having 1 to 10 carbon atoms, a divalent aliphatic cyclic saturated hydrocarbon group having 3 to 20 carbon atoms, a divalent aromatic hydrocarbon group having 6 to 30 carbon atoms, or these And a part or all of the hydrogen atoms of the group of Tsu atom, may be mentioned a halogen atom such as a chlorine atom.

  Specific examples of the linking group E include divalent to tetravalent linking groups represented by the following formulas (E-1) and (E-2).

In the above formulas (E-1) and (E-2), R ^x is an (n + 1) -valent hydrocarbon group. R ^y is a divalent hydrocarbon group. Q is an ether group, carbonyl group, ester group, amide group, urethane group, urea group, carbonate group, imino group or thioether group. n is an integer of 1 to 3. “*” Represents a bond that is bonded to the group represented by the above formula (i).
In said formula (E-1), when n is 2 or 3, several Q and ^Ry have the said definition each independently.

Examples of the (n + 1) -valent hydrocarbon group R ^x include the examples of the (n + 1) -valent hydrocarbon group exemplified in the linking group E.

As an example of the divalent hydrocarbon group R ^y, an example of a divalent hydrocarbon group in the case of n = 1 of the (n + 1) valent hydrocarbon group exemplified in the linking group E can be given. .

  Q is preferably an ether group, a carbonyl group or an ester group from the viewpoint of the ease of synthesis of the monomer giving the structural unit (I).

  Specific examples of the linking group represented by the formula (E-1) include groups represented by the following formulas (E-1-1) to (E-1-6).

  In these, the connection group represented by the said Formula (E-1-1) and (E-1-2) is preferable from a viewpoint of the etching tolerance of the resist film obtained.

  Specific examples of the (n + 1) -valent linking group represented by the above formula (E-2) include groups represented by the following formulas (E-2-1) to (E-2-6). Can do.

  Among these, groups represented by the above formulas (E-2-1) and (E-2-2) are preferable from the viewpoint of etching resistance of the resist film to be obtained.

  The monovalent chain hydrocarbon group represented by Rf in the above formula (1) is, for example, a monovalent chain hydrocarbon group having 1 to 20 carbon atoms, such as a methyl group, an ethyl group, a propyl group, Examples include butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, hexadecyl group, octadecyl group and the like.

  The monovalent aromatic hydrocarbon group represented by Rf in the above formula (1) is, for example, a monovalent aromatic hydrocarbon group having 6 to 30 carbon atoms, such as a phenyl group, a tolyl group, a xylyl group, An aryl group such as a naphthyl group; an aralkyl group such as a benzyl group, a phenethyl group, and a phenylpropyl group.

  Preferable specific examples of the structural unit (I) include a structural unit represented by the above formula (1-1) (hereinafter also referred to as “structural unit (I-1)”).

Examples of the divalent chain organic group represented by R ^a in the above formula (1-1) include the groups exemplified as the divalent chain hydrocarbon group in the linking group E in the above formula (1). .

Examples of the divalent aromatic hydrocarbon group represented by R ^a in the above formula (1-1) include the groups exemplified as the divalent aromatic hydrocarbon group in the linking group E in the above formula (1). .

Examples of the divalent hydrocarbon group having at least one fluorine atom represented by X in the formula (1-1) include a divalent chain hydrocarbon group having 1 to 20 carbon atoms, and 3 to 20 carbon atoms. In which some or all of the hydrogen atoms of the divalent aliphatic cyclic hydrocarbon group or the divalent aromatic hydrocarbon group having 6 to 20 carbon atoms are substituted with fluorine atoms.
The divalent chain hydrocarbon group having 1 to 20 carbon atoms is preferably a divalent hydrocarbon group having 1 to 10 carbon atoms, and more preferably a divalent hydrocarbon group having 1 to 5 carbon atoms.
The divalent aliphatic cyclic hydrocarbon group having 3 to 20 carbon atoms is preferably a monocyclic saturated hydrocarbon group, particularly preferably a cyclopentanediyl group, a cyclohexanediyl group, or a cyclohexylmethanediyl group.
The divalent aromatic hydrocarbon group having 6 to 20 carbon atoms is more preferably a phenylene group, a benzylene group, or a phenethylene group. Among these, a C1-C5 bivalent hydrocarbon group is particularly preferable.

  X preferably has a fluorine atom or a structure having a carbon atom having a fluorine atom at the α-position of the carboxylic acid ester (that is, the carbon atom to which COORf in the above formula (1-1) is bonded), It is more preferable to take a structure having a fluorine atom or a perfluoroalkyl group at the α-position of the carboxylic acid ester. When X has such a structure, the reactivity of the [A] fluoropolymer with respect to the developer can be improved.

  Examples of X include groups represented by the following formulas (X2-1) to (X2-6).

Rf in the above formula (1-1) may be a monovalent aromatic hydrocarbon group optionally having a substituent, a monovalent chain hydrocarbon group having a fluorine atom, or a monovalent having a fluorine atom. Aliphatic cyclic hydrocarbon groups (hereinafter these groups are represented by “Rf ³ ”) are preferred. That is, a preferred example of the structural unit (1-1) includes a structural unit (I-1-1) represented by the following formula (1-1-1).

In the above formula (1-1-1), the definitions of R, R ^a and X are the same as those in the formula (1-1). Rf ³ represents a monovalent aromatic hydrocarbon group which may have a substituent, a monovalent chain hydrocarbon group having a fluorine atom, or a monovalent lipid-preventing cyclic hydrocarbon group having a fluorine atom. It is.

Examples of the monovalent aromatic hydrocarbon group represented by Rf ³ in the above formula (1-1-1) include a monovalent hydrocarbon group having benzene and naphthalene. Examples of such hydrocarbon groups include aryl groups such as phenyl, naphthyl, and tolyl groups; and aralkyl groups such as benzyl and phenethyl groups. Examples of the substituent that the monovalent aromatic hydrocarbon group represented by Rf ³ may have include examples of the substituent that the linking group E of the above formula (1) may have. it can. Among the examples, a halogen atom or R ^S1 is preferable, a fluorine atom or an alkyl group having 1 to 10 carbon atoms in which part or all of a hydrogen atom may be substituted is more preferable, and a fluorine atom or a trifluoromethyl group is particularly preferable. preferable. If Rf ³ is a monovalent aromatic hydrocarbon group preferably has 1 to 5 substituents mentioned above, more preferably to have 1-3, 1-2 has been It is particularly preferable.

Examples of the monovalent chain hydrocarbon group having a fluorine atom represented by Rf ³ in the above formula (1-1-1) include a monovalent chain hydrocarbon having 1 to 30 carbon atoms and having a fluorine atom. Groups.

  Examples of the monovalent chain hydrocarbon group having 1 to 30 carbon atoms having a fluorine atom include a methyl group, an ethyl group, a 1-propyl group, a 2-propyl group, a 1-butyl group, a 2-butyl group, and 2 -(2-methylpropyl) group, 1-pentyl group, 2-pentyl group, 3-pentyl group, 1- (2-methylbutyl) group, 1- (3-methylbutyl) group, 2- (2-methylbutyl) group 2- (3-methylbutyl) group, neopentyl group, 1-hexyl group, 2-hexyl group, 3-hexyl group, 1- (2-methylpentyl) group, 1- (3-methylpentyl) group, 1- (4-methylpentyl) group, 2- (2-methylpentyl) group, 2- (3-methylpentyl) group, 2- (4-methylpentyl) group, 3- (2-methylpentyl) group, 3- (3-methylpentyl) group, octyl group, nonyl group Decyl group, dodecyl group, tetradecyl group, hexadecyl group, and a group obtained by substituting at least one fluorine atom of the hydrogen atom of the like eicosanyl group. Among these, trifluoromethyl group, 2,2,2-trifluoroethyl group, perfluoroethyl group, 2,2,3,3,3-pentafluoropropyl group, 1,1,1,3,3 , 3-hexafluoropropyl group, perfluoro n-propyl group, perfluoro i-propyl group, perfluoro n-butyl group, perfluoro i-butyl group, perfluoro t-butyl group, 2,2,3,3 , 4,4,5,5-octafluoropentyl group, perfluorohexyl group and the like are preferable.

Examples of the monovalent aliphatic cyclic hydrocarbon group having a fluorine atom represented by Rf ³ include a C 3-30 monovalent aliphatic cyclic hydrocarbon group having a fluorine atom.

Examples of the monovalent aliphatic cyclic hydrocarbon group having 3 to 30 carbon atoms having a fluorine atom include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclodecyl group, and a methylcyclohexyl group. Monocyclic saturated hydrocarbon groups such as ethylcyclohexyl group;
Monocyclic unsaturated hydrocarbon groups such as cyclobutenyl, cyclopentenyl, cyclohexenyl, cycloheptenyl, cyclooctenyl, cyclodecenyl, cyclopentadienyl, cyclohexadienyl, cyclooctadienyl, cyclodecadiene ;
Bicyclo [2.2.1] heptyl group, bicyclo [2.2.2] octyl group, tricyclo [5.2.1.0 ^2,6 ] decyl group, tricyclo [3.3.1.1 ^3,7 ] Decyl group, tetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] a polycyclic saturated hydrocarbon group such as a dodecyl group or an adamantyl group;
Bicyclo [2.2.1] heptenyl group, bicyclo [2.2.2] octenyl group, tricyclo [5.2.1.0 ^2,6 ] decenyl group, tricyclo [3.3.1.1 ^3,7 ] Decenyl group, tetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] dodecene and other polycyclic unsaturated hydrocarbon groups and the like substituted at least one hydrogen atom with a fluorine atom.

The group represented by the above Rf ^3, is preferably at least one selected from the group consisting of groups represented by the following formulas from ^{(Rf 3 -a) (Rf 3} -f), the following formula (Rf ³ - At least one selected from the group consisting of groups each represented by a) to (Rf ³ -c) is more preferable.

In the above formulas (Rf ³ -a) to (Rf ³ -d), Rf ³¹ is each independently a monovalent organic group having a fluorine atom. R ^S11 is independently a substituent. n _f1 is independently 0 or 1. n _f11 is an integer of 1 to (5 + 2n _f1 ). n _f12 is an integer of 0 to (5 + 2n _f1 ). However, n _f11 + n _f12 ≦ 5 + 2n _f1 . n _f13 is an integer of 0 to (5 + 2n _f1 ).

Examples of the monovalent organic group having a fluorine atom represented by Rf ³¹ include those similar to Rf ³ described above. Among these, trifluoromethyl group, 2,2,2-trifluoroethyl group, perfluoroethyl group, 2,2,3,3,3-pentafluoropropyl group, 1,1,1,3,3, 3-hexafluoropropyl group, perfluoro n-propyl group, perfluoro i-propyl group, perfluoro n-butyl group, perfluoro i-butyl group, perfluoro t-butyl group, 2,2,3,3 A 4,4,5,5-octafluoropentyl group and a perfluorohexyl group are preferred.

Examples of the monovalent organic group represented by R ^S11 include —R ^{S1 ′} , —R ^{S2 ′} —O—R ^{S1 ′} , —R ^{S2 ′} —CO—R ^{S1 ′} , and —R ^{S2 ′} —CO—. OR ^{S1 ′} , —R ^{S2 ′} —O—CO—R ^{S1 ′} , —R ^{S2 ′} —CN and the like can be mentioned. R ^{S1 ′} is an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or an aryl group having 6 to 30 carbon atoms. R ^{S2 ′} is a single bond, an alkanediyl group having 1 to 10 carbon atoms, a cycloalkanediyl group having 3 to 20 carbon atoms, or an arylene group having 6 to 30 carbon atoms. Among these, —R ^{S1 ′} , —R ^{S2 ′} —O—R ^{S1 ′} , —R ^{S2 ′} —CO—R ^{S1 ′} , —R ^{S2 ′} —CO—OR ^{S1 ′} , —R ^{S2 ′} —O—CO— R ^{S1 ′} is preferred, and —R ^{S1 ′} is more preferred.

In the above formulas (Rf ³ -e) and (Rf ³ -f), the substituent represented by R ⁴¹ is -R ^Q1 , -R ^Q2 -O-R ^Q1 , -R ^Q2 -CO-R ^Q1 ,- ^{R Q2 -CO-OR Q1, -R} Q2 -O-CO-R Q1, -R Q2 -OH, -R Q2 -CN, -R Q2 -COOH (R Q1 is a monovalent chain of 1 to 10 carbon atoms A saturated saturated hydrocarbon group, a monovalent aliphatic cyclic saturated hydrocarbon group having 3 to 20 carbon atoms, or a monovalent aromatic hydrocarbon group having 6 to 30 carbon atoms, and part of hydrogen atoms of these groups Or R ^Q2 may be a single bond, a divalent chain saturated hydrocarbon group having 1 to 10 carbon atoms, or a divalent aliphatic cyclic saturated hydrocarbon having 3 to 20 carbon atoms. Group, a divalent aromatic hydrocarbon group having 6 to 30 carbon atoms, or a part of hydrogen atoms of these groups Or a group substituted entirely with fluorine atoms.

In addition, examples of the aliphatic cyclic hydrocarbon structure formed by combining R ⁴² and R ⁴³ together with the carbon atoms to which they are bonded include a cyclopentyl group, a cyclopentylmethyl group, a 1- (1-cyclopentylethyl) group, 1- ( 2-cyclopentylethyl) group, cyclohexyl group, cyclohexylmethyl group, 1- (1-cyclohexylethyl) group, 1- (2-cyclohexylethyl group), cycloheptyl group, cycloheptylmethyl group, 1- (1-cycloheptyl) Ethyl) group, 1- (2-cycloheptylethyl) group, 2-norbornyl group and the like.

  The structural unit (I-1) is preferably at least one selected from the group consisting of structural units represented by the following formulas (1-1a) to (1-1e). In the following structural unit (I-1), by taking the above structure, the reaction rate of hydrolysis in alkali development is further improved due to its high electron withdrawing property, and the dynamic contact angle of the coating surface is increased. Is further reduced.

In the above formulas (1-1a) to (1-1e), the definitions of R, R ^a , and Rf ³ are the same as those in the above formula (1-1).

  Examples of the structural unit represented by each of the above formulas (1-1a) to (1-1e) include those represented by the following formula.

In the above formula, the definitions of R and Rf ³ are the same as those in the above formula (1).

  Other specific examples of the structural unit (I-1) include those represented by the following formula.

  Another preferred specific example of the structural unit (I) includes a structural unit represented by the above formula (1-2) (hereinafter also referred to as “structural unit (I-2)”).

In the above formula (1-2), R is a hydrogen atom, a fluorine atom, a monovalent chain hydrocarbon group having 1 to 4 carbon atoms, or a monovalent chain having 1 to 4 carbon atoms having at least one halogen atom. It is a chain hydrocarbon group. Rf is a monovalent chain hydrocarbon group or monovalent aromatic hydrocarbon group which may have a fluorine atom. R ^a is ^a divalent chain hydrocarbon group or aromatic hydrocarbon group which may have ^a substituent.

Examples of the divalent chain hydrocarbon group or aromatic hydrocarbon group which may have a substituent represented by R ^a in the above formula (1-2) include those in the above formula (1-1). Examples of ^Ra can be given.

  Another preferred specific example of the structural unit (I) includes a structural unit represented by the above formula (1-3) (hereinafter also referred to as “structural unit (I-3)”).

In the above formula (1-3), R is a hydrogen atom, a fluorine atom, a monovalent chain hydrocarbon group having 1 to 4 carbon atoms, or a monovalent chain having 1 to 4 carbon atoms having at least one halogen atom. It is a chain hydrocarbon group. R ⁰ is a monovalent aromatic hydrocarbon group. Part or all of the hydrogen atoms of this aromatic hydrocarbon group may be substituted with a substituent. R ²¹ represents a methylene group, —CH (CH ₃ ) —, —C (CH ₃ ) ₂ —, —CH ₂ CH ₂ —, or an oxygen atom. R ²² is a hydrogen atom or a substituent.

Examples of the monovalent aromatic hydrocarbon group in which part or all of the hydrogen atoms represented by R ⁰ in the formula (1-3) may be substituted with a substituent include monovalent carbon having benzene and naphthalene, for example. A hydrogen group etc. are mentioned. Such hydrocarbon groups include aryl groups such as phenyl, naphthyl and tolyl groups; aralkyl groups such as benzyl and phenethyl groups, and some or all of the hydrogen atoms of these groups are substituted by substituents. What is being done is mentioned. Examples of the substituent that the monovalent aromatic hydrocarbon group represented by R ⁰ may have include the examples of the substituent that the linking group E may have. Among the above substituents, a halogen atom or R ^P1 is preferable, a fluorine atom or a monovalent chain saturated hydrocarbon group having 1 to 10 carbon atoms in which part or all of hydrogen atoms may be substituted is more preferable, and fluorine An atom or a trifluoromethyl group is particularly preferred. The number of substituents that R ⁰ has is preferably 1 to 5, more preferably 1 to 3, and particularly preferably 1 to 2.

Preferable examples of the group represented by R ⁰ include groups represented by the above formulas (Rf ³ -c) and (Rf ³ -d).

  Another preferred specific example of the structural unit (I) includes a structural unit represented by the above formula (1-4) (hereinafter also referred to as “structural unit (I-4)”).

  R 'in the above formula (1-4) is a C1-C4 monovalent chain hydrocarbon group having at least one fluorine atom. Examples of the monovalent chain hydrocarbon group having 1 to 4 carbon atoms having at least one fluorine atom include a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a fluoroethyl group, a difluoroethyl group, and trifluoro Examples include an ethyl group, a pentafluoroethyl group, a fluoropropyl group, a trifluoropropyl group, a heptafluoropropyl group, a fluorobutyl group, a trifluorobutyl group, and a nonafluorobutyl group.

  Examples of the monovalent chain hydrocarbon group optionally having a fluorine atom represented by Rf in the above formula (1-4) include Rf in the above formula (1).

  Examples of the monovalent aromatic hydrocarbon group optionally having a fluorine atom represented by Rf in the above formula (1-4) include Rf in the above formula (1).

  It is preferable that the content rate of the structural unit (f) with respect to all the structural units in said [A] fluoropolymer is 30 mol% or more and 100 mol% or less. By setting it as such a content rate, sufficient reduction of the dynamic contact angle by development can be achieved with the high dynamic contact angle at the time of immersion exposure.

  In the said radiation sensitive resin composition, it is preferable that [A] fluoropolymer further has at least 1 type of structural unit chosen from the group which consists of structural unit (II) and structural unit (III). The [A] fluoropolymer is formed from the radiation-sensitive resin composition by further having at least one structural unit selected from the group consisting of the structural unit (II) and the structural unit (III). The degree of change in the dynamic contact angle in the development process of the resist film can be further increased.

[Structural unit (II)]
[A] The fluoropolymer may have a structural unit (II) represented by the following formula (2).

In the above formula (2), R is a hydrogen atom, a fluorine atom or a monovalent chain hydrocarbon group having 1 to 4 carbon atoms, and the monovalent chain hydrocarbon group having 1 to 4 carbon atoms is at least 1 May have one halogen atom. G is a single bond, an oxygen atom, a sulfur atom, —CO—O—, —SO ₂ —O—NH—, —CO—NH—, or —O—CO—NH—. R ¹ is a monovalent chain hydrocarbon group having 1 to 6 carbon atoms having at least one fluorine atom or a monovalent aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms having at least one fluorine atom. is there.

  Specific examples of the group represented by R in the structural unit (II) include the example of R in the above formula (1).

Examples of the chain hydrocarbon group having 1 to 6 carbon atoms and having at least one fluorine atom represented by R ¹ in the structural unit (II) include, for example, a trifluoromethyl group and 2,2,2-trifluoroethyl. Group, perfluoroethyl group, 2,2,3,3,3-pentafluoropropyl group, 1,1,1,3,3,3-hexafluoropropyl group, perfluoro n-propyl group, perfluoro i- Propyl group, perfluoro n-butyl group, perfluoro i-butyl group, perfluoro t-butyl group, 2,2,3,3,4,4,5,5-octafluoropentyl group, perfluorohexyl group, etc. Is mentioned.

Examples of the aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms having at least one fluorine atom represented by R ¹ in the structural unit (II) include a monofluorocyclopentyl group, a difluorocyclopentyl group, a perfluoro group. Cyclopentyl, monofluorocyclohexyl, difluorocyclopentyl, perfluorocyclohexylmethyl, fluoronorbornyl, fluoroadamantyl, fluorobornyl, fluoroisobornyl, fluorotricyclodecyl, fluorotetracyclodecyl Etc.

  Examples of the monomer that gives the structural unit (II) include trifluoromethyl (meth) acrylate, 2,2,2-trifluoroethyl (meth) acrylate, and perfluoroethyl (meth) acrylate. Perfluoro n-propyl (meth) acrylate, perfluoro i-propyl (meth) acrylate, perfluoro n-butyl (meth) acrylate, perfluoro i-butyl (meth) acrylate, perfluoro Fluoro 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) Crylate, 1- (2,2,3,3,3-pentafluoropropyl) (meth) acrylate, monofluorocyclopentyl (meth) acrylate, difluorocyclopentyl (meth) acrylate, perfluorocyclopentyl (Meth) acrylic acid ester, monofluorocyclohexyl (meth) acrylic acid ester, difluorocyclopentyl (meth) acrylic acid ester, perfluorocyclohexylmethyl (meth) acrylic acid ester, fluoronorbornyl (meth) acrylic acid ester, fluoroadamantyl (Meth) acrylic acid ester, fluorobornyl (meth) acrylic acid ester, fluoroisobornyl (meth) acrylic acid ester, fluorotricyclodecyl (meth) acrylic acid ester, Oro tetracyclododecene decyl (meth) acrylic acid ester.

  In the above [A] fluoropolymer, the content of the structural unit (II) is preferably such that the total amount of the structural unit (II) with respect to all the structural units constituting the [A] fluoropolymer is 0 mol% to 50 mol%. 0 mol% to 30 mol% is more preferable, and 5 mol% to 30 mol% is particularly preferable. By setting it as such a content rate, the higher dynamic contact angle of the resist film surface can be expressed at the time of immersion exposure. In addition, the [A] fluoropolymer may have the structural unit (II) singly or in combination of two or more.

[Structural unit (III)]
[A] The fluoropolymer may have a structural unit (III) represented by the following formula (3).

In the above formula (3), R is a hydrogen atom, a fluorine atom, or a monovalent chain hydrocarbon group having 1 to 4 carbon atoms, and the monovalent chain hydrocarbon group having 1 to 4 carbon atoms is at least 1 May have one halogen atom. R ² is an (m + 1) -valent hydrocarbon group having 1 to 20 carbon atoms, and an oxygen atom, a sulfur atom, and —NR′— (wherein R ′ is a hydrogen atom or a monovalent group) at the terminal of R ^{2 on} the R ³ side. And a structure in which a carbonyl group, —CO—O— or —CO—NH— is bonded. R ³ is a single bond, a divalent chain hydrocarbon group having 1 to 10 carbon atoms, or a divalent aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms. X ² is a single bond or a divalent chain hydrocarbon group having 1 to 20 carbon atoms and having at least one fluorine atom. A is an oxygen atom, —NR ″ — (where R ″ is a hydrogen atom or a monovalent organic group), —CO—O— * or —SO ₂ —O— * (“*” represents R ⁴ shows a bond to be bonded. R ⁴ is a hydrogen atom or a monovalent organic group. m is an integer of 1-3. However, when m is 2 or 3, several R < ³ >, X < ² >, A and R < ⁴ > have the said definition each independently. )

In the above formula (3), when R ⁴ is a hydrogen atom, it is preferable in that the solubility of the [A] polymer in an alkaline developer can be improved.

In the above formula (3), examples of the monovalent organic group represented by R ⁴ include an acid-dissociable group or a hydrocarbon group having 1 to 30 carbon atoms which may have a substituent.

The “acid-dissociable group” refers to a group that substitutes a hydrogen atom in a polar functional group such as a hydroxyl group or a carboxyl group and dissociates in the presence of an acid. Thereby, the structural unit (III) generates a polar group by the action of an acid. Therefore, in the above formula (3), when R ⁴ is an acid-dissociable group, the solubility in the alkali developer of the exposed portion in the exposure step in the resist pattern forming method described later can be increased. preferable.

  Examples of the acid dissociable group include a t-butoxycarbonyl group, a tetrahydropyranyl group, a tetrahydrofuranyl group, a (thiotetrahydropyranylsulfanyl) methyl group, a (thiotetrahydrofuranylsulfanyl) methyl group, an alkoxy-substituted methyl group, and an alkylsulfanyl group. Examples include substituted methyl groups. In addition, as an alkoxyl group (substituent) in an alkoxy substituted methyl group, there exists a C1-C4 alkoxyl group, for example. Examples of the alkyl group (substituent) in the alkylsulfanyl-substituted methyl group include an alkyl group having 1 to 4 carbon atoms. Moreover, as an acid dissociable group, group represented by the formula (Y-1) described in the term of the structural unit (IV) mentioned later may be sufficient. Among these, in Formula (3), when A is an oxygen atom or —NR ″ —, a t-butoxycarbonyl group or an alkoxy-substituted methyl group is preferable. Moreover, in Formula (3), when A is -CO-O-, it is preferable that it is group represented by the formula (Y-1) described in the term of the structural unit (IV) mentioned later.

In the formula (3), X ² is a divalent chain hydrocarbon group having 1 to 20 carbon atoms and having at least one fluorine atom. Examples of X ² include groups represented by the above formulas (X2-1) to (X2-6).

X ² is preferably a group represented by the above formula (X2-1) when A is an oxygen atom in the above formula (3). In the above formula (3), when A is —CO—O—, it is preferably any one of the groups represented by the above formulas (X2-2) to (X2-6). And more preferably a group represented by the above formula (X2-1).

In addition, in said formula (3), m is an integer of 1-3. Accordingly, 1 to 3 R ⁴ are introduced into the structural unit (III). When m is 2 or 3, R ³ , R ⁴ , X ² and A are each independent. That is, when m is 2 or 3, the plurality of R ⁴ may have the same structure or different structures. When m is 2 or 3, a plurality of R ³ may be bonded to the same carbon atom of R ² or may be bonded to different carbon atoms.

  Examples of the structural unit (III) include structural units represented by the following formulas (3-1a) to (3-1c).

In the formula (3-1a) ~ (3-1c), R 5 is a divalent straight chain, branched or cyclic hydrocarbon group of saturated or unsaturated having 1 to 20 carbon atoms. The definitions of X ² , R ⁴ and m are the same as in the above formula (3). When m is 2 or 3, the plurality of X ² and R ⁴ are each independent.

  Examples of the monomer that gives the structural unit (III) include compounds represented by the following formulas (3m-1) to (3m-6).

In the above formulas (3m-1) to (3m-6), the definition of R is the same as that in the above formula (3). Each R ⁴ is independently a hydrogen atom or a monovalent organic group.

  In the above [A] fluoropolymer, the content of the structural unit (III) is preferably such that the total amount of the structural unit (III) with respect to all structural units constituting the [A] fluoropolymer is 0 mol% to 50 mol%. 5 mol% to 40 mol% is more preferable, and 10 mol% to 30 mol% is particularly preferable. By setting it as such a content rate, the resist film surface formed from the said radiation sensitive resin composition can improve the fall degree of a dynamic contact angle in alkali image development. In addition, the [A] polymer may have structural unit (III) individually by 1 type or in combination of 2 or more types.

[Structural unit (IV)]
The above [A] polymer may have a structural unit (IV) represented by the following formula (4). [A] When a polymer contains structural unit (IV), the shape after the alkali image development of the resist pattern formed from the said radiation sensitive resin composition can be improved more.

  In the above formula (4), R is a hydrogen atom, a fluorine atom or a monovalent chain hydrocarbon group having 1 to 4 carbon atoms, and the monovalent chain hydrocarbon group having 1 to 4 carbon atoms is at least 1 May have one halogen atom. Y is an acid dissociable group.

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

In the above formula (Y-1), R ^p1 represents a monovalent chain hydrocarbon group having 1 to 4 carbon atoms or a monovalent aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms. R ^p2 and R ^p3 are each independently a monovalent chain hydrocarbon group having 1 to 4 carbon atoms or a monovalent aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms, or R ^p2 and R ^p3. Are bonded to each other to form a divalent aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms together with the carbon atoms to which they are bonded.

Among the groups represented by R ^{p1 to} R ^{p3 in the} above formula (Y-1), examples of the monovalent chain hydrocarbon group having 1 to 4 carbon atoms include a methyl group, an ethyl group, and n-propyl. Group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group, t-butyl group and other alkyl groups; vinyl group, allyl group, propenyl group, butenyl group and other alkenyl groups. It is done.

A monovalent aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms, or a divalent fatty acid having 4 to 20 carbon atoms formed together with carbon atoms to which R ^p2 and R ^p3 are bonded to each other. Examples of the group cyclic hydrocarbon group include a bridged skeleton such as an adamantane skeleton and a norbornane skeleton, and a group having a cycloalkane skeleton such as cyclopentane and cyclohexane; these groups include, for example, a methyl group, an ethyl group, n- Groups having an aliphatic cyclic hydrocarbon skeleton such as a group substituted with one or more of linear, branched or cyclic alkyl groups having 1 to 10 carbon atoms such as propyl group and i-propyl group. It is done. Among these, a group having a cycloalkane skeleton is preferable in that the shape of the resist pattern after development can be further improved.

  Examples of the structural unit (IV) include structural units represented by the following formulas (4-1) to (4-4).

In the above formulas (4-1) to (4-4), the definition of R is the same as the above formula (4). R ^{p1 to} R ^p3 are each independently synonymous with the formula (Y-1). R ^p2 and R ^p3 may be bonded to each other to form a divalent aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms together with the carbon atom to which each is bonded. r is an integer of 1 to 3.

  In the [A] fluoropolymer, the content of the structural unit (IV) is preferably such that the total amount of the structural unit (IV) with respect to all the structural units constituting the [A] fluoropolymer is 70 mol% or less. % To 60 mol% is more preferable. By setting such a content, the resist pattern shape after development can be further improved. In addition, the [A] fluoropolymer may have structural unit (IV) individually or in combination of 2 or more types.

[Structural unit (V)]
The [A] fluoropolymer may have a structural unit having an alkali-soluble group (hereinafter also referred to as “structural unit (V)”). [A] When the fluoropolymer contains the structural unit (V), the affinity for the developer can be improved.

  The alkali-soluble group in the structural unit (V) is preferably a functional group having a hydrogen atom having a pKa of 4 to 11 from the viewpoint of improving solubility in a developer. Examples of such functional groups include functional groups represented by the following formulas (5s-1) and (5s-2).

In the formula (5s-1), ^{R 9} is a hydrocarbon group having 1 to 10 carbon atoms and having at least one fluorine atom.

In the above formula (5s-1), the hydrocarbon group having 1 to 10 carbon atoms having at least one fluorine atom represented by R ⁹ is part or all of hydrogen in the hydrocarbon group having 1 to 10 carbon atoms. There is no particular limitation as long as the atom is substituted with a fluorine atom. For example, a trifluoromethyl group is preferable.

  Although it does not specifically limit as a monomer used in order to incorporate the said structural unit (V) in a [A] fluoropolymer, Methacrylic acid ester, acrylic acid ester, or alpha-trifluoroacrylic acid An ester or the like is preferable.

  Examples of the structural unit (V) include structural units derived from (meth) acrylic acid, and those described in paragraphs [0018] to [0022] of WO2009 / 041270 pamphlet.

  In the [A] fluoropolymer, the content of the structural unit (V) is such that the total amount of the structural unit (V) with respect to all the structural units constituting the [A] fluoropolymer is usually 50 mol% or less, and 5 mol % To 30 mol% is preferable, and 5 mol% to 20 mol% is more preferable. By setting such a content, it is possible to achieve a good balance between ensuring water repellency during immersion exposure and improving affinity for the developer during development.

[Structural unit (VI)]
[A] The fluoropolymer may have a structural unit (VI) represented by the following formula (6). [A] When the fluoropolymer contains the structural unit (VI), the affinity for the developer can be improved.

In the above formula (6), R is a hydrogen atom, a fluorine atom or a monovalent chain hydrocarbon group having 1 to 4 carbon atoms, and the monovalent chain hydrocarbon group having 1 to 4 carbon atoms is at least 1 May have one halogen atom. R ^L21 is a single bond or a divalent linking group. R ^L21 is a monovalent organic group having a lactone structure or a monovalent organic group having a cyclic carbonate structure.

Examples of the divalent linking group R ^L21 in the above formula (6) include examples of the divalent linking group in the structural unit (I).

In the above formula (6), examples of the monovalent organic group having a lactone structure represented by R ^Lc include groups represented by the following formulas (Lc-1) to (Lc-6).

In the formulas (Lc-1) to (Lc-6), R ^Lc1 is independently an oxygen atom or a methylene group. R ^Lc2 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. n _Lc1 is each independently 0 or 1. _nLc2 is an integer of 0-3. “*” ^Represents a bond bonded to R ^L21 in the above formula (6). In addition, the groups represented by the formulas (Lc-1) to (Lc-6) may have a substituent.

  Examples of the structural unit (VI) include those described in paragraphs [0054] to [0057] of JP2007-304537A, those described in paragraphs [0086] to [0088] of JP2008-088343A, and Examples include compounds represented by formulas (6-1a) to (6-1j).

  In the above formulas (6-1a) to (6-1j), R is a hydrogen atom, a fluorine atom or a monovalent chain hydrocarbon group having 1 to 4 carbon atoms, and this monovalent chain having 1 to 4 carbon atoms. The chain hydrocarbon group may have at least one halogen atom.

  In addition, the said structural unit (VI) may be contained individually or in combination of 2 or more types. Preferable monomers that give the structural unit (VI) include those described in paragraph [0043] of International Publication No. 2007/116664.

  Among the structural units (VI), examples of the structural unit having a cyclic carbonate structure include a structural unit represented by the following formula (6-2a).

  In said formula (6-2a), R is synonymous with said formula (6). D is a trivalent chain hydrocarbon group having 1 to 30 carbon atoms, a trivalent aliphatic cyclic hydrocarbon group having 3 to 30 carbon atoms, or a trivalent aromatic hydrocarbon group having 6 to 30 carbon atoms. . D may have an oxygen atom, a carbonyl group, or —NH— in its skeleton. D may have a substituent.

  Monomers that give structural units represented by the above formula (6-2a) are described in, for example, Tetrahedron Letters, Vol. 27, no. 32 p. 3741 (1986), Organic Letters, Vol. 4, no. 15 p. 2561 (2002) and the like, and can be synthesized by a conventionally known method.

  Preferable examples of the structural unit represented by the above formula (6-2a) include those described in paragraph [0020] of JP 2010-066653 A, and more preferably the following formula (6-2a-1) And structural units represented by (6-2a-2).

  In the above formulas (6-2a-1) and (6-2a-2), R has the same meaning as in the above formula (6).

  In the [A] fluoropolymer, the content of the structural unit (VI) is such that the total amount of the structural unit (VI) with respect to all the structural units constituting the [A] fluoropolymer is usually 50 mol% or less, and 5 mol % To 40 mol% is preferable, and 5 mol% to 30 mol% is more preferable. By setting it as such a content rate, the sufficient fall of the dynamic contact angle by image development can be achieved with the high dynamic contact angle at the time of immersion exposure.

  [A] The content of the fluorine-containing polymer is based on the total polymer of [A] the fluorine-containing polymer and other polymers to be contained as necessary in the radiation sensitive resin composition. 0.1 mass%-20 mass% are preferable, 0.3 mass%-10 mass% are more preferable, 0.5 mass%-8 mass% are especially preferable. [A] If the content of the fluoropolymer is less than 0.1% by mass, the dynamic contact angle of the resist film obtained from the radiation-sensitive resin composition may vary depending on the location. On the other hand, if this content exceeds 20% by mass, the difference in dissolution of the resist film between the exposed part and the unexposed part becomes small, which may deteriorate the pattern shape.

[[A] Fluoropolymer Production Method]
The [A] fluoropolymer can be synthesized according to a conventional method such as radical polymerization. As a method of radical polymerization, for example, (1) a method in which a solution containing a monomer and a radical initiator is dropped into a reaction solvent or a solution containing a monomer to cause a polymerization reaction; (2) monomer A solution containing a radical initiator and a solution containing a radical initiator are separately dropped into a reaction solvent or a solution containing a monomer to cause a polymerization reaction; (3) a plurality of types each containing a monomer; A method such as a method in which a solution containing a radical initiator and a solution containing a radical initiator are dropped into a reaction solvent or a solution containing a monomer to cause a polymerization reaction is preferable.

  In addition, when the monomer solution is dropped and reacted with respect to the monomer solution, the amount of the monomer in the dropped monomer solution is 30 mol% with respect to the total amount of monomers used for polymerization. Preferably, the amount is 50 mol% or more, more preferably 70 mol% or more.

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

  Examples of the radical initiator used in the polymerization include dimethyl 2,2′-azobis (2-isobutyronitrile), azobisisobutyronitrile (AIBN), 2,2′-azobis (4-methoxy-2). , 4-dimethylvaleronitrile), 2,2′-azobis (2-cyclopropylpropionitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2′-azobis (2- Azo radical initiators such as methyl propionate); peroxide radical initiators such as benzoyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, and the like. Of these, dimethyl 2,2'-azobis (2-isobutyronitrile) is preferred. These can be used alone or in combination of two or more.

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

  The polymer obtained by the polymerization reaction is preferably recovered by a reprecipitation method. That is, after the polymerization reaction is completed, the polymer is recovered as a powder by introducing the polymerization solution into a reprecipitation solvent. As the reprecipitation solvent, alcohols or alkanes can be used alone or in admixture 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.

  Although the polystyrene conversion weight average molecular weight (Mw) by the gel permeation chromatography (GPC) of said [A] polymer is not specifically limited, It is preferable that it is 1,000-50,000, and 1,000-40,000. It is more preferable that it is 1,000-30,000, and it is especially preferable. [A] When the Mw of the fluoropolymer is less than 1,000, a resist film having a sufficient dynamic contact angle may not be obtained. On the other hand, if the Mw of the [A] polymer exceeds 50,000, the developability of the resist film may be lowered.

  Moreover, ratio (Mw / Mn) of Mw with respect to polystyrene conversion number average molecular weight (Mn) by GPC of said [A] polymer is 1.0-5.0 normally, and is 1.0-4.0. It is preferable that it is 1.0 to 2.0.

[Low molecular weight polymer content]
In the radiation sensitive resin composition, the content of the [A] fluoropolymer having a molecular weight of 1,000 or less (hereinafter also referred to as “low molecular weight polymer”) is 0.02% by mass or less. Is preferable, 0.017 mass% or less is more preferable, and 0.014 mass% or less is further more preferable. Storage stability improves further by making content of the low molecular weight polymer of the said radiation sensitive resin composition into the said range. The reason why the storage stability is improved by making the content of the low molecular weight polymer of the radiation sensitive resin composition in the above range is not necessarily clear, but for example, such a low molecular weight polymer is [A] Compared with the higher molecular weight component of the fluoropolymer, the hydrolysis reaction of the base-dissociable group is likely to occur, which is likely to cause generation of particles in the liquid. Therefore, it is considered that a reduction in the content of the low molecular weight polymer leads to an improvement in storage stability. The low molecular weight polymer content in the radiation sensitive resin composition can be measured using a gas chromatograph-mass spectrometer (GC-MS).

  As a method for producing the radiation-sensitive resin composition having a low low molecular weight polymer content, [A] a good solvent for the fluorinated polymer and [A] a fluoropolymer solution or synthetic polymerization reaction solution [A] Fluoropolymer such as a method of treating by a liquid-liquid purification method using a poor solvent, [A] a polymerization reaction liquid when synthesizing a fluorinated polymer, and a prepared radiation-sensitive resin composition A method of filtering a solution containing an ultrafiltration membrane, a method of synthesizing and using a high molecular weight polymer or a polymer having a narrow molecular weight distribution as the [A] fluorine-containing polymer, or [A] a fluorine-containing polymer as a solvent For example, a method of reducing and using a low molecular weight polymer by dissolving and reprecipitating in the solution can be used.

<[B] polymer>
The radiation-sensitive resin composition has a [B] acid-dissociable group separately from the [A] fluoropolymer, and a polymer having a smaller fluorine atom content than the above [A] fluoropolymer ( Hereinafter, it is also preferable to contain simply “[B] polymer”. Such a polymer having an acid-dissociable group is insoluble or hardly soluble in alkali prior to the action of an acid. When the acid-dissociable group is eliminated by the action of an acid generated from a [C] acid generator, which will be described later, the polymer is alkali. It becomes soluble. The polymer is “alkali-insoluble or hardly alkali-soluble” means that the resist film is formed under the alkali development conditions employed when forming a resist pattern from the resist film formed using the radiation-sensitive resin composition. Instead, when a film having a thickness of 100 nm using only such a polymer is developed, 50% or more of the initial film thickness of the film remains after development.

When the said radiation sensitive resin composition contains a [B] polymer further, when forming a resist film from the radiation sensitive resin composition containing a [A] fluorine-containing polymer and a [B] polymer. [A] The degree of uneven distribution of the fluorine-containing polymer on the resist coating surface is increased. As a result, the hydrophobicity of the above-mentioned [A] fluoropolymer and the characteristics resulting from the reduction thereof are more efficiently expressed. The fluorine atom content can be measured by ¹³ C-NMR.

  [B] The specific structure of the polymer is not particularly limited as long as it is a polymer having the above-described properties, but [A] in the above formula (3) for the fluoropolymer It is preferable to have the structural unit (III) represented and the structural unit (VI) represented by the above formula (6).

  In the above [B] polymer, the content of the structural unit (III) is preferably such that the total amount of the structural unit (III) with respect to all the structural units constituting the [B] polymer is 0 to 30 mol%, and 0 to 15 mol. % Is more preferable. If the content exceeds 30 mol%, the adhesion with the substrate is insufficient and the pattern may be peeled off.

  In the above [B] polymer, the content of the structural unit (VI) is preferably such that the total amount of the structural unit (VI) with respect to all the structural units constituting the [B] polymer is 5 mol to 75 mol%, and 15 mol to 65 mol. % Is more preferable, and 25 mol to 55 mol% is particularly preferable. If the content is less than 5 mol%, the adhesiveness to the substrate as a resist becomes insufficient and the pattern may be peeled off. On the other hand, if the content exceeds 75 mol%, the contrast after dissolution is impaired, and the pattern shape may be lowered.

  [B] The polymer may have a structural unit other than the structural unit (III) and the structural unit (VI) as long as it has the fluorine atom content. Examples of the polymerizable unsaturated monomer constituting the other structural unit include monomers disclosed in International Publication No. 2007 / 116664A [0065] to [0085].

Other structural units include
Structural units derived from 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, or 3-hydroxypropyl (meth) acrylate;
The structural unit (V);
A structural unit represented by the following formula (o-1) or the like is preferable.

In the above formula (o-1), R is a hydrogen atom, a fluorine atom or a monovalent chain hydrocarbon group having 1 to 4 carbon atoms, and this monovalent chain hydrocarbon group having 1 to 4 carbon atoms is It may have at least one halogen atom. R ^o1 is a divalent linking group.

Examples of the divalent linking group represented by R ^o1 in the above formula (o-1) include examples of the divalent linking group in the structural unit (I).

  [B] The Mw of the polymer is usually 3,000 to 300,000, preferably 4,000 to 200,000, and more preferably 4,000 to 100,000. If Mw is less than 3,000, the heat resistance as a resist may be reduced. On the other hand, if Mw exceeds 300,000, the developability as a resist may be lowered.

  In the said radiation sensitive resin composition, it is preferable that content of [A] fluoropolymer is 0.1 to 10 mass parts with respect to 100 mass parts of [B] polymers. [A] By setting the content of the fluoropolymer in the above range, segregation of the [A] fluoropolymer to the surface of the resist film occurs effectively, so that elution from the resist film is further suppressed. At the same time, since the dynamic contact angle on the resist coating surface is further increased, water drainage can be further improved.

<[C] Radiation sensitive acid generator>
The radiation sensitive resin composition of the present invention preferably contains a [C] radiation sensitive acid generator (hereinafter also simply referred to as “[C] acid generator”). [C] Examples of the acid generator include onium salt compounds such as sulfonium salts and iodonium salts, organic halogen compounds, and sulfone compounds such as disulfones and diazomethane sulfones. [C] An acid generator can be used individually or in combination of 2 or more types.

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

  [C] Specific examples of the acid generator include diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, and bis (4-t-butylphenyl) iodonium. Trifluoromethanesulfonate, bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate, bis (4-t-butylphenyl) iodonium perfluoro-n-octanesulfonate, triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium Nonafluoro-n-butanesulfonate, triphenylsulfonium perfluoro-n-octanesulfonate, cyclohexyl 2-oxocyclohexyl Methylsulfonium trifluoromethanesulfonate, dicyclohexyl-2-oxocyclohexylsulfonium trifluoromethanesulfonate, 2-oxocyclohexyldimethylsulfonium trifluoromethanesulfonate, 4-hydroxy-1-naphthyldimethylsulfonium trifluoromethanesulfonate, 4-hydroxy-1-naphthyltetrahydro Thiophenium trifluoromethanesulfonate, 4-hydroxy-1-naphthyltetrahydrothiophenium nonafluoro-n-butanesulfonate, 4-hydroxy-1-naphthyltetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (1- Naphthylacetomethyl) tetrahydrothiophenium trifluoromethanesulfonate, 1- ( -Naphthylacetomethyl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (1-naphthylacetomethyl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (3,5-dimethyl-4-hydroxy Phenyl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) Tetrahydrothiophenium perfluoro-n-octane sulfonate, trifluoromethanesulfonyl bicyclo [2.2.1] hept-5-ene-2,3-dicarbodiimide, nonafluoro-n-butanesulfonyl bicyclo [2.2.1 ] Hept-5-ene-2,3-dicarbodiimide, perfluoro-n-octanesulfonylbicyclo [2.2.1] hept-5-ene-2,3-dicarbodiimide, N-hydroxysuccinimide trifluoromethane Preferred are sulfonate, N-hydroxysuccinimide nonafluoro-n-butane sulfonate, N-hydroxysuccinimide perfluoro-n-octane sulfonate, 1,8-naphthalenedicarboxylic acid imide trifluoromethanesulfonate. These can be used alone or in combination of two or more.

  [C] As a blending amount of the acid generator, from the viewpoint of ensuring the sensitivity and developability as a resist, 0.1 mass with respect to 100 mass parts of the total amount of the polymer contained in the radiation-sensitive resin composition. Part-30 mass parts is preferable, and 0.1 mass part-20 mass parts is more preferable. When the blending amount of the acid generator is less than 0.1 parts by mass, the sensitivity and developability tend to decrease, and when it exceeds 30 parts by mass, the transparency to radiation decreases and it is difficult to obtain a rectangular resist pattern. Tend to be.

<[D] Acid diffusion controller>
[D] Examples of the acid diffusion controller include a compound represented by the following formula (8) (hereinafter also referred to as “nitrogen-containing compound (I)”), a compound having two nitrogen atoms in the same molecule (hereinafter referred to as “nitrogen-containing compound (I)”) , “Nitrogen-containing compound (II)”), compounds having 3 or more nitrogen atoms (hereinafter also referred to as “nitrogen-containing compound (III)”), amide group-containing compounds, urea compounds, nitrogen-containing heterocycles. Compounds and the like. [D] When an acid diffusion control agent is contained, the pattern shape and dimensional fidelity as a resist can be improved. [D] The acid diffusion controller can be used alone or in combination of two or more.

In said formula (8), R < ¹² > -R < ¹⁴ > is respectively independently a hydrogen atom, the linear, branched or cyclic alkyl group, aryl group, or aralkyl group which may be substituted.

Examples of the nitrogen-containing compound (I) include monoalkylamines such as n-hexylamine;
Dialkylamines such as di-n-butylamine;
Trialkylamines such as triethylamine;
And aromatic amines such as aniline.

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

  Examples of the nitrogen-containing compound (III) include polymers of polyethyleneimine, polyallylamine, dimethylaminoethylacrylamide, and the like.

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

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

  Examples of the nitrogen-containing heterocyclic compound include pyridines such as pyridine and 2-methylpyridine, pyrazine, pyrazole and the like.

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

In addition, as the acid diffusion controller, a compound represented by the following formula (9) can also be used.
X ⁺ Z ^- ··· (9)

In the above formula (9), X ⁺ is a cation represented by the following formula (9-1-1) or (9-1-2). Z ⁻ is an anion represented by OH ⁻ , R ^D1 —COO ^— , an anion represented by R ^D1 —SO ₃ ^— , or an anion represented by R ^D1 —N ⁻ —SO ₂ —RD ² . However, R ^D1 represents an optionally substituted alkyl group, a monovalent aliphatic cyclic hydrocarbon group, or an aryl group. R ^D2 is an alkyl group or a monovalent aliphatic cyclic hydrocarbon group in which some or all of the hydrogen atoms are substituted with fluorine atoms.

In the above formula (9-1-1), R ^{D3 to} R ^D5 each independently represent a hydrogen atom, an alkyl group, an alkoxyl group, a hydroxyl group, or a halogen atom. In the above formula (9-1-2), R ^D6 and R ^D7 each independently represent a hydrogen atom, an alkyl group, an alkoxyl group, a hydroxyl group, or a halogen atom.

  The above compound is used as an acid diffusion control agent that is decomposed by exposure and loses acid diffusion controllability (hereinafter also referred to as “photodegradable acid diffusion control agent”). By containing this compound, the acid diffuses in the exposed area and the acid diffusion is controlled in the unexposed area, so that the contrast between the exposed area and the unexposed area is excellent, that is, the boundary between the exposed area and the unexposed area. Since the portion becomes clear, it is particularly effective for improving the LWR (Line Width Roughness) and MEEF (Mask Error Enhancement Factor) of the radiation-sensitive resin composition of the present invention.

X ⁺ in the above formula (9) is a cation represented by the general formula (9-1-1) or (9-1-2) as described above. R ^{D3 to} R ^D5 in the formula (9-1-1) are each independently a hydrogen atom, an alkyl group, an alkoxyl group, a hydroxyl group, or a halogen atom, and among these, A hydrogen atom, an alkyl group, an alkoxy group, and a halogen atom are preferred because of the effect of lowering the solubility in a developer. In addition, R ^D6 and R ^D7 in the above formula (9-1-2) are each independently a hydrogen atom, an alkyl group, an alkoxyl group, a hydroxyl group, or a halogen atom, and among these, a hydrogen atom, an alkyl group A halogen atom is preferred.

^Z in the above formula (9) - ^are, OH ^-, R D1 -COO ^- anion represented ^by, R D1 -SO ₃ ^- anion represented, the formula ^R D1 ^-N - _-SO 2 ^{-R D2} An anion represented by However, R ^D1 in these formulas is an optionally substituted alkyl group, aliphatic cyclic hydrocarbon group or aryl group, and among these, the effect of lowering the solubility of the above-mentioned compound in a developer is effective. For this reason, an aliphatic cyclic hydrocarbon group or an aryl group is preferable.

As the alkyl group which may be substituted in the above formula (9), for example, a hydroxyalkyl group having 1 to 4 carbon atoms such as a hydroxymethyl group;
An alkoxyl group having 1 to 4 carbon atoms such as a methoxy group;
A cyano group;
And a group having one or more substituents such as a cyanoalkyl group having 2 to 5 carbon atoms such as a cyanomethyl group. Among these, a hydroxymethyl group, a cyano group, and a cyanomethyl group are preferable.

  Examples of the optionally substituted aliphatic cyclic hydrocarbon group in the above formula (9) include cycloalkane skeletons such as hydroxycyclopentane, hydroxycyclohexane, and cyclohexanone; 1,7,7-trimethylbicyclo [2.2.1]. And a monovalent group derived from an aliphatic cyclic hydrocarbon such as a bridged aliphatic cyclic hydrocarbon skeleton such as heptan-2-one (camphor). Among these, a group derived from 1,7,7-trimethylbicyclo [2.2.1] heptan-2-one is preferable.

  Examples of the aryl group which may be substituted in the above formula (9) include a phenyl group, a benzyl group, a phenylethyl group, a phenylpropyl group, a phenylcyclohexyl group and the like. And the like substituted with a group. Among these, a phenyl group, a benzyl group, and a phenylcyclohexyl group are preferable.

Z in the above formula (9) ^- is an anion represented by the following formula (9-2-1) ^{(i.e., R D1} is ^R D1 -COO a phenyl group ^- anion represented by), the following formula ( 9-2-2) (ie, R ^D1 is a group derived from 1,7,7-trimethylbicyclo [2.2.1] heptan-2-one, and is represented by R ^D1 —SO ₃ ^— . Anion) or an anion represented by the following formula (9-2-3) (that is, R ^D1 is a butyl group, and R ^D2 is a trifluoromethyl group, R ^D1 —N ^— SO ₂ —R ^D2 Anion represented by

  The photodegradable acid diffusion controller is represented by the general formula (9), and specifically, is a sulfonium salt compound or an iodonium salt compound that satisfies the above conditions.

  Examples of the sulfonium salt compounds include triphenylsulfonium hydroxide, triphenylsulfonium salicylate, triphenylsulfonium 4-trifluoromethyl salicylate, diphenyl-4-hydroxyphenylsulfonium salicylate, triphenylsulfonium 10-camphor sulfone. Nert, 4-t-butoxyphenyl diphenylsulfonium 10-camphorsulfonate and the like.

  Examples of the iodonium salt compound include bis (4-t-butylphenyl) iodonium hydroxide, bis (4-t-butylphenyl) iodonium salicylate, bis (4-t-butylphenyl) iodonium 4-trifluoromethyl salicylate. Examples include tilate and bis (4-t-butylphenyl) iodonium 10-camphorsulfonate.

  [D] The content of the acid diffusion controller is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less with respect to 100 parts by mass of the total amount of the polymer contained in the radiation-sensitive resin composition. If the acid diffusion controller is excessively contained, the sensitivity of the formed resist film may be remarkably lowered.

<[E] solvent>
The radiation-sensitive resin composition usually contains an [E] solvent. [E] The solvent is not particularly limited as long as it is a solvent capable of dissolving at least the [A] fluorine-containing polymer, and the optionally contained [B] polymer, [C] acid generator and the like. Such solvents include, for example, linear or branched ketones;
Cyclic ketones;
Propylene glycol monoalkyl ether acetates;
Alkyl 2-hydroxypropionates;
Examples include alkyl 3-alkoxypropionates.
Of these, from the viewpoint of storage stability of the radiation-sensitive resin composition, linear or branched ketones, cyclic ketones, and propylene glycol monoalkyl ether acetates are preferable, and propylene glycol monomethyl ether acetate. And cyclohexanone is more preferred.

  In addition, from the viewpoint of further improving the storage stability of the radiation-sensitive resin composition, the solubility parameter (Solubility Parameter: SP value) of the [E] solvent is preferably 8 to 11, and 8.5 to 10.7. Is more preferable, and 9 to 10.5 is more preferable. [E] The reason why the storage stability of the radiation-sensitive resin composition is improved when the solubility parameter of the solvent is in the above range is, for example, suppressing the hydrolysis reaction of the base-dissociable group during storage, It is conceivable that the precipitation of particles is suppressed. These can be used alone or in combination of two or more. The SP value can be obtained by, for example, the Fedors method. The method is described in POLYMER ENGINEERING AND SCIENCE, FEBRUARY, 1974, vol. 14, Issue 2, p. 147-154.

<Other optional components>
In addition to the above, the radiation-sensitive resin composition of the present invention contains an uneven distribution accelerator, a surfactant, an alicyclic skeleton-containing compound, a sensitizer, a crosslinking agent, etc. as other optional components as necessary. can do.

[Uneven distribution promoter]
The uneven distribution accelerator has the effect of segregating the [A] fluoropolymer more efficiently on the resist film surface. By adding the uneven distribution accelerator to the radiation sensitive resin composition, the amount of the [A] fluoropolymer 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 damaging the basic resist characteristics such as LWR, development defects, and pattern collapse resistance, and to perform immersion exposure at a higher speed by high-speed scanning. As a result, it is possible to improve the hydrophobicity of the resist film surface which suppresses immersion-derived defects such as watermark defects. Examples of such an uneven distribution promoter include low molecular compounds having a relative dielectric constant of 30 or more and 200 or less and a boiling point of 100 ° C. or more at 1 atm. Examples of such compounds include lactone compounds, carbonate compounds, nitrile compounds, and polyhydric alcohols. These can be used alone or in combination of two or more.

  Examples of the lactone compound include γ-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.

  The content of the uneven distribution accelerator is preferably 10 parts by mass to 500 parts by mass, and more preferably 30 parts by mass to 300 parts by mass when the total amount of the polymer is 100 parts by mass.

[Surfactant]
A surfactant is a component that exhibits an effect of improving coatability, developability, and the like. Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol diacrylate. In addition to nonionic surfactants such as stearate, KP341 (Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (Kyoeisha Chemical Co., Ltd.), F-Top EF301, EF303, EF352 (Tochem Products), MegaFuck F171, F173 (Dainippon Ink and Chemicals), Florard FC430, FC431 (Sumitomo 3M), Asahi Examples include Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (Asahi Glass Co., Ltd.). These can be used alone or in combination of two or more.

  As content of surfactant, it is 2 mass parts or less normally with respect to 100 mass parts of total amounts of the polymer contained in the said radiation sensitive resin composition.

[Alicyclic skeleton-containing compound]
The alicyclic skeleton-containing compound is a component having an action of further improving dry etching resistance, pattern shape, adhesion to a substrate, and the like.

Examples of the alicyclic skeleton-containing compound include adamantane derivatives such as 1-adamantanecarboxylic acid, 2-adamantanone, and 1-adamantanecarboxylic acid t-butyl;
Deoxycholic acid esters such as t-butyl deoxycholate, t-butoxycarbonylmethyl deoxycholic acid, 2-ethoxyethyl deoxycholic acid;
Lithocholic acid esters such as t-butyl lithocholic acid, t-butoxycarbonylmethyl lithocholic acid, 2-ethoxyethyl lithocholic acid;
3- [2-Hydroxy-2,2-bis (trifluoromethyl) ethyl] tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodecane, 2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo [4.2.1.0 ^3,7 ] nonane, and the like. These can be used alone or in combination of two or more.

  As a compounding quantity of an alicyclic skeleton containing compound, it is 50 mass parts or less normally with respect to 100 mass parts of total amounts of the polymer contained in the said radiation sensitive resin composition, and 30 mass parts or less are preferable.

[Sensitizer]
The sensitizer absorbs energy other than the energy of radiation absorbed by the [C] acid generator, and transmits the energy to the [C] acid generator in the form of, for example, electrons and radicals, thereby It has the effect of increasing the amount of acid produced, and has the effect of improving the “apparent sensitivity” of the 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 can be used alone or in combination of two or more.

[Crosslinking agent]
When the radiation-sensitive resin composition of the present invention is used as a negative-type radiation-sensitive resin composition, a compound capable of crosslinking a polymer soluble in an alkali developer in the presence of an acid (hereinafter referred to as “crosslinking agent”). May be blended). Examples of the crosslinking agent include compounds having at least one functional group having a crosslinking reactivity with a polymer soluble in an alkali developer (hereinafter, sometimes referred to as “crosslinkable functional group”). .

  Examples of the crosslinkable functional group include glycidyl ether group, glycidyl ester group, glycidyl amino group, methoxymethyl group, ethoxymethyl group, benzyloxymethyl group, acetoxymethyl group, benzoyloxymethyl group, formyl group, acetyl group, vinyl Group, isopropenyl group, (dimethylamino) methyl group, (diethylamino) methyl group, (dimethylolamino) methyl group, (diethylolamino) methyl group, morpholinomethyl group and the like.

  Examples of the crosslinking agent include those described in paragraphs [0169] to [0172] of WO2009 / 51088.

  As the crosslinking agent, a methoxymethyl group-containing compound is preferable, and dimethoxymethylurea, tetramethoxymethylglycoluril and the like are more preferable. These can be used alone or in combination of two or more.

  As a usage-amount of a crosslinking agent, 5 mass parts-95 mass parts are preferable with respect to 100 mass parts of polymers soluble in an alkali developing solution, 15 mass parts-85 mass parts are more preferable, 20 mass parts-75 mass parts. Part by mass is particularly preferred. If the amount of the crosslinking agent used is less than 5 parts by mass, the remaining film ratio tends to decrease, the pattern meanders or swells easily, and if it exceeds 95 parts by mass, the alkali developability tends to decrease. .

[Others]
The radiation-sensitive resin composition can also contain a dye, a pigment, an adhesion aid and the like in addition to the above-described other optional components. For example, by using a dye or a pigment, the latent image of the exposed area can be visualized, and the influence of halation during exposure can be reduced. Moreover, the adhesiveness with a board | substrate can be improved by mix | blending an adhesion aid. Examples of other additives include alkali-soluble resins, low-molecular alkali-solubility control agents having an acid-dissociable protecting group, antihalation agents, storage stabilizers, antifoaming agents, and the like. These can be used alone or in combination of two or more.

[metal]
The total content of metals in the radiation-sensitive resin composition of the present invention needs to be 30 mass ppb or less, preferably 20 mass ppb or less, and more preferably 10 mass ppb or less. The said radiation sensitive resin composition becomes the thing excellent in storage stability because the total content of a metal shall be 30 mass ppb or less. That is, it is possible to obtain a radiation-sensitive resin composition in which generation of particles is suppressed even during long-term storage and sensitivity and a change in the receding contact angle of the resulting resist film are small.

  The reason why the storage stability is improved by setting the metal content in the radiation-sensitive resin composition to 30 mass ppb or less is not necessarily clear, but the metal in the radiation-sensitive resin composition is probably [A]. It serves as a catalyst for the hydrolysis reaction of the base-dissociable group of the fluorinated polymer, and the hydrolysis reaction can be suppressed by keeping the metal content below a certain value. It is conceivable that an increase in the number of particles generated due to this, a decrease in receding contact angle on the surface of the resulting resist film, a change in sensitivity of the composition, and the like are suppressed. Moreover, since aggregation in a solvent of a resin having a metal as a core as an impurity is reduced, the number of particles in the liquid may be reduced.

  The upper limit of the ratio (M / A) of the total metal content M (mass ppb) to the content A (mass%) of the [A] fluoropolymer in the radiation-sensitive resin composition is preferably 180, 120 is more preferable, and 60 is more preferable. By setting the content ratio of the total metal content and the [A] fluoropolymer in the radiation-sensitive resin composition within the above range, the storage stability is further improved. The reason why the above ratio and storage stability correlate is, for example, that the metal is involved in the base dissociable group of the [A] fluorine-containing polymer and the storage stability is lowered.

  Examples of the metal contained in the radiation sensitive resin composition include sodium, potassium, magnesium, calcium, copper, aluminum, iron, manganese, tin, chromium, nickel, zinc, lead, titanium, zirconium, silver, platinum, etc. Is mentioned. It does not specifically limit as a form of the metal contained in the said radiation sensitive resin composition, A metal cation, a metal complex, a metal metal, an ionic compound, etc. are mentioned. Each content and total content of the metal in a radiation sensitive resin composition can be measured by ICP-MS method (Inductively Coupled Plasma-Mass Spectrum) etc.

  Among the above metals, the contents of sodium, magnesium, and iron are preferably 3 mass ppb or less. Sodium, magnesium, and iron have a particularly large catalytic effect on the above hydrolysis reaction and a particle generation rate due to the metal as a nucleus compared to other metals. Therefore, the storage stability of the radiation-sensitive resin composition is stable. It has been shown that the effect on sex is significant. Accordingly, the content of at least one metal is preferably 3 mass ppb or less, and the content of all these metals is more preferably 3 mass ppb or less.

  From the above viewpoint, in the radiation-sensitive resin composition, when the metal content is M (mass ppb) and the total content of sodium, magnesium and iron among these metals is S (mass ppb), Q = As the converted metal content Q (mass ppb) obtained by the formula of 3.2 × S + M, 40 mass ppb is preferable, 30 mass ppb is more preferable, and 20 mass ppb is more preferable.

  As a method of setting the total content of metals in the radiation-sensitive resin composition within the above range, a radiation-sensitive resin composition having a metal content exceeding 30 mass ppb is used as a raw material, for example, a nylon 66 membrane is used as a filtration medium. The method of filtering with the used filter, an ion exchange filter, etc. is mentioned.

[water]
In the said radiation sensitive resin composition, it is preferable that water content is 3 mass% or less, 1.5 mass% or less is more preferable, and 0.3 mass% or less is further more preferable. By setting the water content of the radiation-sensitive resin composition in the above range, the storage stability over a long period of time is further improved. The reason why the storage stability is improved by setting the water content of the radiation-sensitive resin composition to a certain value or less is not necessarily clear, but can be considered as follows, for example. That is, it is considered that the presence of water in the radiation-sensitive resin composition promotes the hydrolysis reaction of the base-dissociable group of the [A] fluoropolymer during storage. And since a carboxyl group etc. generate | occur | produce by the said hydrolysis and the compatibility in the composition of a [A] fluoropolymer falls, generation | occurrence | production of a particle is estimated to occur. Therefore, according to the said radiation sensitive resin composition whose water content is below a fixed value, particle generation is suppressed. The acid generation efficiency of the radiation-sensitive acid generator in the composition is considered to be affected by the presence of the generated carboxyl group and the like. Therefore, according to the said radiation sensitive resin composition, the fluctuation | variation of the radiation sensitivity can be suppressed. Furthermore, the hydrophobicity of the [A] fluoropolymer decreases due to hydrolysis during storage of the radiation-sensitive resin composition. However, according to the radiation-sensitive resin composition, since such hydrolysis is suppressed and generation of polar groups such as carboxyl groups from the base-dissociable groups is suppressed, the radiation-sensitive resin after storage It is considered that the decrease and fluctuation of the receding contact angle on the resist film surface obtained from the composition can be suppressed. In addition, content of the water in a radiation sensitive resin composition can be measured by the Karl Fischer method.

  As a method of setting the content of water contained in the radiation-sensitive resin composition to 3% by mass or less, a method of performing distillation or addition of a desiccant with respect to the solvent used for preparing the radiation-sensitive resin composition, radiation sensitivity And a method of treating the functional resin composition by nitrogen bubbling. In addition, hygroscopic substances such as [A] fluoropolymers, [B] polymers, especially [C] acid generators, etc. used in the preparation of the radiation sensitive resin composition are controlled under dry conditions to contain water. The method of suppressing is also effective.

<Method for producing radiation-sensitive resin composition>
The radiation-sensitive resin composition is usually dissolved in the solvent so that the total solid content concentration is 1% by mass to 50% by mass, and preferably 3% by mass to 25% by mass. It is prepared as a composition solution by filtering with a filter of about 0.02 μm.

  The manufacturing method of the radiation sensitive resin composition of this invention has the process of filtering the solution containing a [A] fluoropolymer with a nylon filter or an ion exchange filter. [A] By filtering the solution containing the fluoropolymer with a nylon filter or an ion exchange filter, the content of the metal in the radiation-sensitive resin composition can be easily and reliably set within the above range. It can be manufactured easily and reliably while suppressing an increase in the cost of the radiation resin composition.

  The solution containing the [A] fluoropolymer to be filtered is not particularly limited as long as it contains the [A] fluoropolymer. Even if it is a solution of the prepared radiation-sensitive resin composition, the solution containing the [A] It may be a solution obtained by dissolving a fluoropolymer in a solvent, or a polymerization reaction solution when the [A] fluoropolymer is synthesized by polymerization or the like.

  Nylon filters that can be used in the production method of the present invention are not particularly limited, but as commercially available products, for example, “Photoclean EZD” manufactured by Nippon Pole, “Photoclean DDF” manufactured by Japan Pole, “ Ultiplez / P-nylon "and the like. Although it does not specifically limit as a hole diameter of the said nylon filter, 2-150 nm is preferable, 5-100 nm is more preferable, 10-70 nm is further more preferable. If the pore size of the nylon filter exceeds 150 nm, it is necessary to treat with a large number of filters in order to reduce the total metal content of the radiation-sensitive resin composition of the present invention, which may complicate the production method. is there. On the other hand, if the pore size of the nylon filter is smaller than 2 nm, the processing speed becomes very small, and it may take a long time for production.

  Although it does not specifically limit as an ion exchange filter which can be used for the manufacturing method of this invention, The cation exchange type filter by which the ion exchange group was fixed to the polyethylene porous membrane or the polypropylene porous membrane is preferable. Such an ion exchange filter is not particularly limited, and examples of commercially available products include “Ion Clean” manufactured by Pall Japan.

  In addition to the above method, the method for reducing the content of the metal or the like of the radiation sensitive resin composition includes, for example, chemical purification methods such as water washing, liquid-liquid extraction, and the like, and these chemical purification methods. Known methods such as a combination with physical purification methods such as filtration and centrifugation can be employed.

  Moreover, in the said manufacturing method, in order to reduce content of water, it is preferable to have the process of performing a dehydration process further. As a method for performing such a dehydration treatment, for example, a method of bubbling a gas into a solution containing the above [A] fluoropolymer can be mentioned. By adopting a method of bubbling gas, the water content in the radiation-sensitive resin composition can be reduced to a certain value or less very easily. As the gas used for bubbling, for example, an inert gas such as nitrogen or argon can be used, and air or the like can be used from a low-cost viewpoint, but it affects the quality of the resulting radiation-sensitive resin composition. From the viewpoint of preventing this, it is preferable to use an inert gas, and it is more preferable to use nitrogen among them. The gas used for bubbling preferably has a low content of water vapor. The content of the water vapor contained is preferably less than 10,000 ppm by mass, more preferably less than 1,000 ppm by mass, and even more preferably less than 100 ppm by mass. The temperature of the solution containing the [A] fluoropolymer for bubbling gas is not particularly limited as long as it is equal to or lower than the boiling point of this solution. For example, 0 to 100 ° C, preferably 10 to 70 ° C, more preferably 15 to 40 ° C.

  In the production method, the content of the low molecular weight polymer of the [A] fluoropolymer in the radiation sensitive resin composition is reduced to further improve the storage stability of the composition. You may have the process of processing the solution containing a [A] fluoropolymer before or after by a liquid-liquid purification method. The liquid-liquid purification method is a method of adjusting the content of the low molecular weight polymer using a good solvent and a poor solvent for the [A] fluoropolymer. Usually, after adding a good solvent to the solution containing the [A] fluorine-containing polymer, this solution is put into a poor solvent, and the resulting good solvent layer is recovered to adjust the content of the low molecular weight polymer. Processing is performed.

  In this case, the solution containing the [A] fluoropolymer is not particularly limited as long as it contains the [A] fluoropolymer, and is a solution obtained by dissolving the [A] fluoropolymer in a solvent. Alternatively, it may be a polymerization reaction solution when the [A] fluoropolymer is synthesized by polymerization, or a solution obtained by further adding a solvent to these solutions or contained in these solutions A solution obtained by removing a part or all of the solvent by distillation or the like may be used. The good solvent / poor solvent combination, the amount used, and the ratio thereof are appropriately selected depending on the type and molecular weight of the [A] fluoropolymer. Examples of the good solvent include methanol, ethanol, and the like. Alcohols such as acetone, 2-butanone and methyl isobutyl ketone; ethers such as tetrahydrofuran, dioxane, ethylene glycol dimethyl ether and diethylene glycol dimethyl ether; esters such as ethyl acetate, ethylene glycol monomethyl ether acetate and propylene glycol monomethyl ether acetate; These mixed solvents are exemplified. Examples of the poor solvent include hydrocarbons such as n-pentane, n-hexane, n-heptane, cyclohexane, benzene, and toluene. [A] The number of times of treatment by the liquid-liquid purification method for the solution containing the fluoropolymer may be one time or may be repeated a plurality of times. [A] Since the low molecular weight polymer content of the fluoropolymer can be further reduced, it is preferably repeated a plurality of times.

  Moreover, in the said manufacturing method, as a method of reducing the content of the low molecular weight polymer of [A] fluoropolymer and further improving the storage stability of the said composition, before the said metal content adjustment process process, Or you may have the process of filtering the solution containing a [A] fluoropolymer later with an ultrafiltration membrane later.

  In this case, the solution to be filtered using the ultrafiltration membrane is not particularly limited as long as it contains the [A] fluoropolymer, and even the prepared solution of the radiation sensitive resin composition contains [A]. It may be a solution obtained by dissolving a fluoropolymer in a solvent, or may be a polymerization reaction solution obtained by synthesizing [A] a fluoropolymer by polymerization. Further, a solvent may be added to these solutions. A solution obtained by adding or removing a part or all of the solvent contained in these solutions by distillation or the like may be used.

  The ultrafiltration membrane used is not particularly limited as long as it can remove at least a part of the low molecular weight polymer of [A] fluoropolymer, and a general ultrafiltration membrane is used. Can be used. Examples of the material of the ultrafiltration membrane include cellulose, polysulfone, polyamide, ceramics, and the like, but ceramics are preferable from the viewpoint of solvent resistance. The lower limit of the molecular weight cut-off of the ultrafiltration membrane is preferably 700, more preferably 800, and even more preferably 1,000. Examples of the shape of the ultrafiltration membrane include a flat membrane, a cylindrical shape, a hollow fiber, a spiral, and the like, but a cylindrical shape is preferable because a high permeation flow rate is possible and clogging is small.

<Method for forming photoresist pattern>
The resist pattern forming method using the radiation-sensitive resin composition is (1) a step of forming a photoresist film on a substrate using the radiation-sensitive resin composition (hereinafter also referred to as “step (1)”). (2) A step of placing an immersion exposure liquid on the photoresist film and subjecting the photoresist film to immersion exposure via the immersion exposure liquid (hereinafter also referred to as “step (2)”). And (3) a step of developing the photoresist film subjected to immersion exposure to form a resist pattern (hereinafter also referred to as “step (3)”). In the forming method, since the radiation-sensitive resin composition is used as a photoresist composition, the film surface has high water drainage, and the process time is shortened by high-speed scanning exposure, and the occurrence of development defects is suppressed. A good resist pattern can be formed efficiently.

  In the above step (1), the solution of the radiation-sensitive resin composition of the present invention is applied to a substrate such as a silicon wafer or a wafer coated with aluminum by an appropriate application means such as spin coating, cast coating or roll coating. A photoresist film is formed by applying on top. Specifically, after applying the radiation-sensitive resin composition solution so that the resulting resist film has a predetermined thickness, the solvent in the coating film is volatilized by pre-baking to form a resist film.

  The thickness of the resist film is preferably 10 nm to 5,000 nm, and more preferably 10 nm to 2,000 nm.

  Although the prebaking heating conditions vary depending on the composition of the radiation-sensitive resin composition, the prebaking temperature is preferably about 30 ° C to 200 ° C, more preferably 50 ° C to 150 ° C. The prebaking time is preferably 10 seconds to 300 seconds, and more preferably 20 seconds to 200 seconds.

  In the step (2), an immersion exposure liquid is disposed on the photoresist film formed in the step (1), and the photoresist film is immersed by irradiation with radiation through the immersion exposure liquid. .

  Examples of the immersion exposure liquid include pure water, long-chain or cyclic aliphatic compounds, and fluorine-based inert liquids.

  The radiation is appropriately selected from visible rays, ultraviolet rays, far ultraviolet rays, X-rays, charged particle beams, etc., depending on the type of acid generator used. ArF excimer laser (wavelength 193 nm) or Far ultraviolet rays typified by a KrF excimer laser (wavelength 248 nm) are preferable, and an ArF excimer laser (wavelength 193 nm) is more preferable.

  Moreover, exposure conditions, such as exposure amount, can be suitably selected according to the composition of the radiation-sensitive resin composition, the type of additive, and the like.

  In the present invention, it is preferable to perform heat treatment (PEB) after exposure. By this PEB, the dissociation reaction of the acid dissociable group in the resin component can proceed smoothly. The heating condition of PEB is appropriately adjusted depending on the composition of the radiation sensitive resin composition, but the temperature of PEB is preferably 30 ° C to 200 ° C, more preferably 50 ° C to 170 ° C. The PEB time is preferably 10 seconds to 300 seconds, more preferably 20 seconds to 200 seconds.

  In the present invention, in order to maximize the potential of the radiation-sensitive resin composition, it is used as disclosed in, for example, Japanese Patent Publication No. 6-12452 (Japanese Patent Application Laid-Open No. 59-93448). An organic or inorganic antireflection film may be formed on the substrate. In order to prevent the influence of basic impurities contained in the environmental atmosphere, a protective film can be provided on the photoresist film as disclosed in, for example, Japanese Patent Laid-Open No. 5-188598. Further, in order to prevent the acid generator and the like from flowing out of the photoresist film in the immersion exposure, an immersion protective film is formed on the photoresist film as disclosed in, for example, JP-A-2005-352384. It can also be provided. Moreover, these techniques can be used together.

  In addition, in the resist pattern formation method by immersion exposure, only the photoresist film obtained by using the radiation-sensitive resin composition of the present invention without providing the above-described protective film (upper layer film) on the photoresist film. Thus, a resist pattern can be formed. When a resist pattern is formed using such an upper film-free photoresist film, a protective film (upper film) forming step can be omitted, and an improvement in throughput can be expected.

  In the step (3), a predetermined resist pattern is formed by developing the exposed resist film.

  Examples of the developer used in the development step include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, Triethylamine, methyldiethylamine, ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, 1,5-diazabicyclo- [ 4.3.0] An alkaline aqueous solution in which at least one alkaline compound such as 5-nonene is dissolved is preferable.

  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 may be added to the developer composed of the alkaline aqueous solution. Examples of the organic solvent include ketones such as acetone, methyl ethyl ketone, methyl i-butyl ketone, cyclopentanone, cyclohexanone, 3-methylcyclopentanone, and 2,6-dimethylcyclohexanone;
Alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, t-butyl alcohol, cyclopentanol, cyclohexanol, 1,4-hexanediol, 1,4-hexanedimethylol Kind;
Ethers such as tetrahydrofuran and dioxane;
Esters such as ethyl acetate, n-butyl acetate, i-amyl acetate;
Aromatic hydrocarbons such as toluene and xylene, phenol, acetonyl acetone, dimethylformamide and the like can be mentioned. These can be used alone or in combination of two or more.

  As the usage-amount of an organic solvent, 100 volume parts or less are preferable with respect to 100 volume parts of alkaline aqueous solution. When the usage-amount of an organic solvent exceeds 100 volume part, developability may fall and there exists a possibility that the image development residue of an exposure part may increase. An appropriate amount of a surfactant or the like can be added to the developer composed of the alkaline aqueous solution. In addition, after developing with the developing solution which consists of alkaline aqueous solution, generally it wash | cleans with water and dries.

  Using the radiation-sensitive resin composition of the present invention, the resist pattern obtained as described above has suppressed degradation of film performance due to elution from the resist film, and has various defects such as watermark defects and development defects. Since generation is suppressed, it has a good pattern property and is suitable for fine processing using a physographic technique. In addition, since the radiation-sensitive resin composition is excellent in storage stability, it is possible to obtain a high-quality resist product under simple management because variations and variations in various characteristics due to differences in storage periods are small. .

  EXAMPLES Hereinafter, although this invention is explained in full detail based on an Example, this invention is not interpreted limitedly based on description of this Example. The measuring method of various physical property values is shown below.

[Weight average molecular weight (Mw)]
The weight average molecular weight (Mw) was measured under the analysis conditions using a GPC column (2 G2000HXL, 1 G3000HXL, 1 G4000HXL) manufactured by Tosoh Corporation, a flow rate of 1.0 mL / min, tetrahydrofuran as an elution solvent, and a column temperature of 40 ° C. Measured by gel permeation chromatography using monodisperse polystyrene as a standard.

[ ¹³ C-NMR analysis]
The ¹³ C-NMR analysis for determining each structural unit content of the polymer was measured using a nuclear magnetic resonance apparatus (“JNM-ECX400” manufactured by JEOL Ltd.).

<[A] Synthesis of fluoropolymer>
[A] Polymers (A-1) to (A-11), which are fluoropolymers, were converted to compounds represented by the following formulas (M-1) to (M-15) (hereinafter referred to as “compound (M -1) to (M-15) ".) Was used and synthesized according to the following procedure.

[Synthesis Example 1] (Synthesis of polymer (A-1))
42.7 g (60 mol%) of the compound (M-4) and 57.3 g (40 mol%) of the compound (M-5) were dissolved in 200 g of 2-butanone, and 2,2′-azobisisobutyronitrile 3 was further dissolved. .2 g was added to prepare a monomer solution. On the other hand, 100 g of 2-butanone was put into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes.
After purging with nitrogen, the inside of the three-necked flask was heated to 80 ° C. while stirring. Subsequently, the monomer solution prepared in advance was dropped over 3 hours using a dropping funnel. After completion of dropping, the mixture was further stirred at 80 ° C. for 3 hours.
After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or less by water cooling. Then, this polymerization solution was put into 2,000 g of methanol to precipitate a white powder, which was then filtered off. The filtered white powder was washed twice with 300 g of methanol and then filtered. Next, the white powder was dried at 50 ° C. for 17 hours to obtain a colorless solid copolymer (yield 72 g, yield 72%). As a result of ¹³ C-NMR analysis, the content (mol%) of the structural unit derived from the compound (M-4) and the compound (M-5) was 61:39, respectively. This is referred to as a polymer (A-1). The Mw of this copolymer was 7,500.

[Synthesis Example 2] (Synthesis of polymer (A-2))
Compound (M-4) 11.1 g (20 mol%) and compound (M-5) 88.9 g (80 mol%) were dissolved in 2-butanone 200 g, and 2,2′-azobisisobutyronitrile 2 was further dissolved. .49 g was added to prepare a monomer solution. On the other hand, 100 g of 2-butanone was put into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes.
After purging with nitrogen, the inside of the three-necked flask was heated to 80 ° C. while stirring. Subsequently, the monomer solution prepared in advance was dropped over 3 hours using a dropping funnel. After completion of dropping, the mixture was further stirred at 80 ° C. for 3 hours.
After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or less by water cooling. Then, this polymerization solution was put into 2,000 g of methanol to precipitate a white powder, which was then filtered off. The filtered white powder was washed twice with 300 g of methanol and then filtered. Next, the white powder was dried at 50 ° C. for 17 hours to obtain a colorless solid copolymer (yield 70 g, yield 70%). As a result of ¹³ C-NMR analysis, the content (mol%) of the structural unit derived from the compound (M-4) and the compound (M-5) was 20:80, respectively. This is referred to as a polymer (A-2). The Mw of this copolymer was 7,300.

[Synthesis Example 3] (Synthesis of Polymer (A-3))
100 g (100 mol%) of the compound (M-5) was dissolved in 200 g of 2-butanone, and 2.24 g of 2,2′-azobisisobutyronitrile was further added to prepare a monomer solution. On the other hand, 100 g of 2-butanone was put into a 1,000 ml three-necked flask and purged with nitrogen gas for 30 minutes. After purging with nitrogen, the inside of the three-necked flask was heated to 80 ° C. while stirring. Subsequently, the monomer solution prepared in advance was dropped over 3 hours using a dropping funnel. After completion of dropping, the mixture was further stirred at 80 ° C. for 3 hours.
After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or less by water cooling. Then, this polymerization solution was put into 2,000 g of methanol to precipitate a white powder, which was then filtered off. The filtered white powder was washed twice with 300 g of methanol and then filtered. Subsequently, the white powder was dried at 50 ° C. for 17 hours to obtain a colorless solid polymer (yield 75 g, yield 75%). This is referred to as a polymer (A-3). The Mw of this polymer was 7,400.

[Synthesis Example 4] (Synthesis of Polymer (A-4))
15.4 g (20 mol%) of the compound (M-4) and 84.6 g (80 mol%) of the compound (M-6) were dissolved in 200 g of 2-butanone, and 2,2′-azobisisobutyronitrile 3 was further dissolved. .47 g was added to prepare a monomer solution. On the other hand, 100 g of 2-butanone was put into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes.
After purging with nitrogen, the inside of the three-necked flask was heated to 80 ° C. while stirring. Subsequently, the monomer solution prepared in advance was dropped over 3 hours using a dropping funnel. After completion of dropping, the mixture was further stirred at 80 ° C. for 3 hours.
After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or less by water cooling. Then, this polymerization solution was put into 2,000 g of methanol to precipitate a white powder, which was then filtered off. The filtered white powder was washed twice with 300 g of methanol and then filtered. Next, the white powder was dried at 50 ° C. for 17 hours to obtain a colorless solid copolymer (yield 72 g, yield 72%). As a result of ¹³ C-NMR analysis, the content (mol%) of the structural unit derived from the compound (M-4) and the compound (M-5) was 21:79, respectively. This is referred to as a polymer (A-4). The Mw of this copolymer was 6,400.

[Synthesis Example 5] (Synthesis of Polymer (A-5))
11.6 g (20 mol%) of the compound (M-4) and 88.4 g (80 mol%) of the compound (M-7) are dissolved in 200 g of 2-butanone, and 2,2′-azobisisobutyronitrile is further dissolved. 2.61 g was added to prepare a monomer solution. On the other hand, 100 g of 2-butanone was put into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes.
After purging with nitrogen, the inside of the three-necked flask was heated to 80 ° C. while stirring. Subsequently, the monomer solution prepared in advance was dropped over 3 hours using a dropping funnel. After completion of dropping, the mixture was further stirred at 80 ° C. for 3 hours.
After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or less by water cooling. Then, this polymerization solution was put into 2,000 g of methanol to precipitate a white solid, which was then filtered off. The white solid separated by filtration was washed twice with 400 g of methanol and then filtered. Next, the white solid was dried at 60 ° C. for 17 hours to obtain a white solid copolymer (yield 70 g, yield 70%). As a result of ¹³ C-NMR analysis, the content (mol%) of the structural unit derived from the compound (M-4) and the compound (M-7) was 21:79, respectively. This is referred to as “polymer (A-5)”. The Mw of this copolymer was 7,500.

[Synthesis Example 6] (Synthesis of Polymer (A-6))
13.8 g (20 mol%) of the compound (M-8) and 86.2 g (80 mol%) of the compound (M-9) were dissolved in 200 g of 2-butanone, and 2,2′-azobisisobutyronitrile was further dissolved. 2.13 g was added to prepare a monomer solution. On the other hand, 100 g of 2-butanone was put into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes.
After purging with nitrogen, the inside of the three-necked flask was heated to 80 ° C. while stirring. Subsequently, the monomer solution prepared in advance was dropped over 3 hours using a dropping funnel. After completion of dropping, the mixture was further stirred at 80 ° C. for 3 hours.
After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or less by water cooling. Then, this polymerization solution was put into 2,000 g of methanol to precipitate a white solid, which was then filtered off. The filtered white solid was twice washed with 400 g of methanol and then filtered. Then, the white solid was dried at 60 ° C. for 17 hours to obtain a white solid copolymer (yield 65 g, yield 65%). As a result of ¹³ C-NMR analysis, the content (mol%) of the structural unit derived from the compound (M-8) and the compound (M-9) was 20:80, respectively. This is referred to as a polymer (A-6). The Mw of this copolymer was 7,300.

[Synthesis Example 7] (Synthesis of Polymer (A-7))
Compound (M-9) 78.1 g (75 mol%) and compound (M-10) 21.9 g (25 mol%) were dissolved in 2-butanone 200 g, and 2,2′-azobisisobutyronitrile was further dissolved. 2.05 g was added to prepare a monomer solution. On the other hand, 100 g of 2-butanone was put into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes.
After purging with nitrogen, the inside of the three-necked flask was heated to 80 ° C. while stirring. Subsequently, the monomer solution prepared in advance was dropped over 3 hours using a dropping funnel. After completion of dropping, the mixture was further stirred at 80 ° C. for 3 hours.
After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or less by water cooling. Then, this polymerization solution was put into 2,000 g of methanol to precipitate a white solid, which was then filtered off. The filtered white solid was twice washed with 400 g of methanol and then filtered. Next, the white solid was dried at 60 ° C. for 17 hours to obtain a white solid copolymer (yield 68 g, yield 68%). As a result of ¹³ C-NMR analysis, the content (mol%) of the repeating units derived from the compound (M-9) and the compound (M-10) was 76:24, respectively. This is designated as polymer (A-7). The Mw of this copolymer was 7,600.

[Synthesis Example 8] (Synthesis of polymer (A-8))
16.3 g (30 mol%) of the compound (M-4) and 83.7 g (70 mol%) of the compound (M-11) are dissolved in 200 g of 2-butanone, and 2,2′-azobisisobutyronitrile is further dissolved. 2.44 g was added to prepare a monomer solution. On the other hand, 100 g of 2-butanone was put into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes.
After purging with nitrogen, the inside of the three-necked flask was heated to 80 ° C. while stirring. Subsequently, the monomer solution prepared in advance was dropped over 3 hours using a dropping funnel. After completion of dropping, the mixture was further stirred at 80 ° C. for 3 hours.
After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or less by water cooling. Then, this polymerization solution was put into 2,000 g of methanol to precipitate a white solid, which was then filtered off. The filtered white solid was twice washed with 400 g of methanol and then filtered. Next, the white solid was dried at 60 ° C. for 17 hours to obtain a white solid copolymer (yield 68 g, yield 68%). As a result of ¹³ C-NMR analysis, the content (mol%) of the structural unit derived from the compound (M-4) and the compound (M-11) was 33:67, respectively. This is referred to as a polymer (A-8). The Mw of this copolymer was 7,200.

[Synthesis Example 9] (Synthesis of Polymer (A-9))
16.0 g (20 mol%) of compound (M-4) and 84.0 g (80 mol%) of compound (M-12) were dissolved in 200 g of 2-butanone, and 2,2′-azobisisobutyronitrile was further dissolved. 3.59 g was added to prepare a monomer solution. On the other hand, 100 g of 2-butanone was put into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes.
After purging with nitrogen, the inside of the three-necked flask was heated to 80 ° C. while stirring. Subsequently, the monomer solution prepared in advance was dropped over 3 hours using a dropping funnel. After completion of dropping, the mixture was further stirred at 80 ° C. for 3 hours.
After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or less by water cooling. Then, this polymerization solution was put into 2,000 g of methanol to precipitate a white solid, which was then filtered off. The filtered white solid was twice washed with 400 g of methanol and then filtered. Next, the white solid was dried at 60 ° C. for 17 hours to obtain a colorless solid copolymer (yield 64 g, yield 64%). As a result of ¹³ C-NMR analysis, the content (mol%) of the structural unit derived from the compound (M-4) and the compound (M-12) was 23:77, respectively. This is referred to as a polymer (A-9). The Mw of this copolymer was 7,400.

[Synthesis Example 10] (Synthesis of Polymer (A-10))
14.0 g (20 mol%) of the compound (M-4) and 86.0 g (80 mol%) of the compound (M-13) are dissolved in 200 g of 2-butanone, and 2,2′-azobisisobutyronitrile is further dissolved. 3.15 g was added to prepare a monomer solution. On the other hand, 100 g of 2-butanone was put into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes.
After purging with nitrogen, the inside of the three-necked flask was heated to 80 ° C. while stirring. Subsequently, the monomer solution prepared in advance was dropped over 3 hours using a dropping funnel. After completion of dropping, the mixture was further stirred at 80 ° C. for 3 hours.
After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or less by water cooling. Then, this polymerization solution was put into 2,000 g of methanol to precipitate a white solid, which was then filtered off. The filtered white solid was twice washed with 400 g of methanol and then filtered. Next, the white solid was dried at 60 ° C. for 17 hours to obtain a white solid copolymer (yield 63 g, yield 63%). As a result of ¹³ C-NMR analysis, the content (mol%) of the structural unit derived from the compound (M-4) and the compound (M-12) was 24:76, respectively. This is referred to as a polymer (A-10). The Mw of this copolymer was 7,300.

[Synthesis Example 11] (Synthesis of Polymer (A-11))
18.8 g (30 mol%) of the compound (M-4), 5.4 g (10 mol%) of the compound (M-15) and 75.8 g (60 mol%) of the compound (M-14) were dissolved in 200 g of 2-butanone. Further, 2.82 g of 2,2′-azobisisobutyronitrile was added to prepare a monomer solution. On the other hand, 100 g of 2-butanone was put into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes.
After purging with nitrogen, the inside of the three-necked flask was heated to 80 ° C. while stirring. Subsequently, the monomer solution prepared in advance was dropped over 3 hours using a dropping funnel. After completion of dropping, the mixture was further stirred at 80 ° C. for 3 hours.
After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or less by water cooling. Then, this polymerization solution was put into 2,000 g of methanol to precipitate a white solid, which was then filtered off. The filtered white solid was twice washed with 400 g of methanol and then filtered. Next, the white solid was dried at 60 ° C. for 17 hours to obtain a colorless solid copolymer (yield 64 g, yield 64%). As a result of ¹³ C-NMR analysis, the content (mol%) of the structural unit derived from the compound (M-4), the compound (M-15) and the compound (M-14) was 32:11:57, respectively. . This is referred to as a polymer (A-11). The Mw of this copolymer was 7,600.

<[A] Purification of fluoropolymer>
When the synthesized [A] fluorine-containing polymer (polymers (A-1) to (A-11)) is used for the preparation of the radiation-sensitive resin composition, the obtained [A] fluorine-containing polymer is obtained. The combined polymerization reaction solution was used after the following purification operation.
(I) The polymerization reaction solution of [A] fluoropolymer was concentrated until the solid content concentration became 50% by mass. The concentrated liquid was transferred to a separatory funnel, and an equal mass of methanol was added to the concentrated liquid to uniformly dilute the concentrated liquid, and then 4 times as much n-hexane as the concentrated liquid mass was added and mixed.
(Ii) The obtained lower layer was recovered, transferred to a separatory funnel, and then 2-butanone 0.2 times the mass of the concentrate was added, again with the same mass of methanol, and then with the same mass of n. -Hexane was added and mixed.
(Iii) The above operation (ii) was repeated once more.
(Iv) The resulting lower layer was solvent-substituted with propylene glycol monomethyl ether acetate solvent using an evaporator to obtain a 25% by weight solution of [A] fluoropolymer.
(V) The above solution was used as a [A] fluoropolymer solution for the preparation of the radiation sensitive resin composition.

<[B] Synthesis of polymer>
[Synthesis Example 12] (Synthesis of Polymer (B-1))
Compound (M-1) 33.11 g (40 mol%), compound (M-2) 12.22 g (10 mol%) and compound (M-3) 54.67 g (50 mol%) were converted into 2-butanone 200 g. In addition, 8.08 g of 2,2′-azobisisobutyronitrile was added to prepare a monomer solution. On the other hand, 100 g of 2-butanone was put into a 1,000 mL three-necked flask and purged with nitrogen gas for 30 minutes.
After purging with nitrogen, 2-butanone in the three-necked flask was heated to 80 ° C. with stirring. Subsequently, the monomer solution prepared in advance was dropped over 3 hours using a dropping funnel. After completion of dropping, the mixture was further stirred at 80 ° C. for 3 hours.
After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or less by water cooling. Then, this polymerization reaction solution was put into 2,000 g of methanol to precipitate a white powder, which was then filtered off. The white powder separated by filtration was twice washed with 400 g of methanol and then filtered. Next, the white powder (copolymer) was dried at 50 ° C. for 17 hours (yield 80.1 g, yield 80%). As a result of ¹³ C-NMR analysis, the content (mol%) of the structural unit derived from the compound (M-1), the compound (M-2) and the compound (M-3) was 41:10:49, respectively. . This is referred to as a polymer (B-1). Mw of this polymer (B-1) was 7,300.

<Preparation of radiation-sensitive resin composition>
Components ([C] acid generator, [D] acid diffusion inhibitor, [E] constituting the radiation-sensitive resin composition other than [A] fluoropolymer and [B] polymer synthesized in the above synthesis example. The solvent is shown below.

[C] Acid generator (C-1) 4-cyclohexylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate (C-2) triphenylsulfonium-tricyclo [3.3.1.1 ^3,7 ] decanyl difluoromethane Sulfonate

[D] Acid diffusion inhibitor (D-1) tert-butyl-4-hydroxy-1-piperidinecarboxylate (D-2) 2,6-diisopropylaniline

[E] Solvent (E-1) Propylene glycol monomethyl ether acetate (E-2) Cyclohexanone

[Example 1]
Polymer (A-1) solution obtained by the above purification containing 5 parts by mass of polymer (A-1), 100 parts by mass of polymer (B-1), and 6 parts by mass of acid generator (C-1). And (C-2) 6 parts by mass, acid diffusion inhibitor (D-1) 0.8 part by mass, and solvent (E-1) 1,980 parts by mass (the amount brought in from the [A] fluoropolymer solution) And 848 parts by mass of the solvent (E-2) were mixed to obtain a uniform solution. The obtained homogeneous solution had a low molecular weight polymer content of 0.009% by mass. The obtained solution was further filtered using a HDPE filter “Photoclean DDF PE-clean” having a pore diameter of 10 nm and a nylon filter “Photoclean DDF Ultipleat / P-nylon” having a pore diameter of 10 nm. A radiation sensitive resin composition was prepared.

[Examples 2 to 11]
The radiation sensitive resin compositions of Examples 2 to 11 were prepared in the same manner as in Example 1 except that the components and the blending amounts shown in Table 1 below were used as the components constituting the radiation sensitive resin composition.

[Example 12]
In Example 1, instead of using a nylon filter “Photoclean DDF Ultiplez P-Nylon” having a pore size of 10 nm, the same feeling as in Example 12 was used except that a filter having a pore size of 20 nm was used. A radiation resin composition was prepared.

[Examples 13 and 14]
Example 13 and Example 13 were carried out in the same manner as in Example 1 except that a nylon filter “Photoclean DDF Ultiplez / P-nylon” having a pore diameter of 10 nm was used instead of a nylon filter having a pore diameter of 30 nm. The radiation sensitive resin composition of Example 14 was prepared. In Example 14, a solvent having a high water content was used as the solvent (F-1).

[Examples 15 and 16]
Example 15 and Example 15 were carried out in the same manner as in Example 1 except that a nylon filter “Photoclean DDF Ultiplez / P-nylon” having a pore diameter of 10 nm was used instead of a nylon filter having a pore diameter of 40 nm. The radiation sensitive resin composition of Example 16 was prepared. In Example 16, a solvent having a high water content was used as the solvent (F-1).

[Comparative Examples 1-3]
The components constituting the radiation-sensitive resin composition were the types and blending amounts shown in Table 1 below, and the filtration was conducted using a membrane filter having a pore diameter of 200 nm instead of the nylon filter in the same manner as in Example 1. Radiation sensitive resin compositions of Comparative Examples 1 to 3 were prepared.

[Comparative Example 4]
In Comparative Example 1, the radiation-sensitive resin composition of Comparative Example 4 was the same as Comparative Example 1 except that the filtrate obtained by the membrane filter was subjected to nitrogen bubbling to reduce the water content in the liquid. I got a thing.

<Each content measurement>
About each radiation sensitive resin composition of the said Example and comparative example, each content was measured by the following method about the composition after storing for 90 days at room temperature and a dark place after preparation.

[Metal content]
Each radiation-sensitive resin composition was diluted 10 times with nitric acid, and using ICP-MS (“ELAN DRCII” manufactured by Perkin Elmer), Na, K, Mg, Ca, contained in the radiation-sensitive resin composition Each content about the metal of Cu, Al, Fe, Mn, Sn, Cr, Ni, Zn, Pb, Ti, Zr, Ag, and Pt was measured. Moreover, the total content was calculated from the measured value of each content.

[Water content]
The amount (% by mass) of water contained in each radiation-sensitive resin composition was determined using a trace moisture measuring device (Mitsubishi Chemical Corporation). ) AX ”was measured by Karl Fischer method using“ Aquamicron (registered trademark) CXU ”manufactured by API Corporation.

[Low molecular weight polymer content]
The content (mass%) of the low molecular weight polymer in each radiation-sensitive resin composition, that is, the [A] fluoropolymer having a molecular weight of 1,000 or less was measured by the following method.
50 g of the radiation sensitive resin composition was weighed into an eggplant-shaped flask, the solvent was distilled off with an evaporator at a bath temperature of 30 ° C. over 2 days, the mass of the remaining solid was measured, and the radiation sensitive resin composition The solid content concentration (% by mass) was calculated.
Based on the calculated solid content concentration, 100 g of the radiation sensitive resin composition was concentrated until the solid content concentration became 25% in the same manner as in the above operation. The obtained concentrated liquid was slowly added dropwise to 10-fold mass n-hexane which was being stirred to precipitate insoluble components. The obtained suspension was filtered through a 0.1 μm membrane filter, and the filtrate mass of the obtained filtrate (hereinafter referred to as “(1)”, unit: g) was measured.
N-Hexane is completely distilled off from the filtrate using an evaporator, the mass of the resulting residue is measured, and the residue component concentration in the filtrate (hereinafter referred to as “(2)”. Unit: mass%). Calculated.
Each component in the residue was identified using a gas chromatograph-mass spectrometer (GC-MS: Thermo Scientific ITQ900), and the components corresponding to the low molecular weight polymer were selected. Furthermore, using GC (hydrogen flame ionization detector (FID): Thermo Scientific TRACE GC Ultra), the ratio of the components of the low molecular weight polymer in the residue (hereinafter referred to as “(3)”) (Unit: mass%).
The content (mass%) of the low molecular weight polymer contained in the radiation-sensitive resin composition was determined from the obtained values (1) to (3) using the following formula (L).
Low molecular weight polymer content (% by mass) in the radiation sensitive resin composition
= Mass of low molecular weight polymer in radiation sensitive resin composition / mass of radiation sensitive resin composition (100 g) × 100
= [(1) × {(2) / 100} × {(3) / 100}] × 100/100
= (1) × (2) × (3) / 10,000 (L)

<Evaluation method>
Each radiation-sensitive resin composition prepared in the above Examples and Comparative Examples was measured and evaluated for each of the following items using the composition immediately after preparation and after being stored in a predetermined number of days, room temperature, and dark place. .

[Number of particles in liquid]
In the above Examples and Comparative Examples, the composition after storage and after storage for 30 days in a dark place at room temperature was subjected to radiation sensitivity using an in-liquid particle counter (“KS-41” manufactured by Rion Co., Ltd.). The number of particles of 0.15 μm or more contained per 1 mL of the resin composition was measured.
When the number of particles in the liquid after storage for 30 days after preparation is 0 or more and 10 or less is “◯”, when it exceeds 10 and is 50 or less, “△”, when it exceeds 50 Was evaluated as “×”.

[Backward contact angle]
In the above examples and comparative examples, the receding contact angle of the resist film formed from the radiation-sensitive resin composition was determined according to the following procedure immediately after the preparation and after the preparation and after storage for 30 days in the dark at room temperature. ,It was measured.
(1) Formation of antireflection layer A composition for forming a lower antireflection film (trade name “ARC66”, manufactured by Nissan Chemical Co., Ltd.) on a 12-inch silicon wafer surface, a semiconductor manufacturing apparatus (model name “Lithius Pro-i”), Spin coating using Tokyo Electron). Next, pre-baking (PB) (205 ° C., 60 seconds) was performed to form an antireflection layer having a thickness of 105 nm.
(2) Formation of photoresist layer Thereafter, the photoresist composition was spin-coated using a semiconductor manufacturing apparatus (model name “CLEAN TRACK ACT12”, manufactured by Tokyo Electron Ltd.). Then, PB (110 ° C., 60 seconds) and cooling (23 ° C., 30 seconds) were performed to form a 100 nm-thick photoresist layer.
(3) Measurement of contact angle The receding contact angle of the formed coating film was measured according to the following procedure using “DSA-10” manufactured by KRUS under an environment of room temperature 23 ° C., humidity 45% and normal pressure.
First, the wafer stage position is adjusted. Next, the wafer is set on the stage. Water is injected into the “DSA-10” needle. Next, the position of the needle is finely adjusted. Next, water is discharged from the needle to form a 25 μL water droplet on the wafer, and then the needle is once pulled out of the water droplet. Next, the needle is pulled down again to the finely adjusted position. Subsequently, a water droplet is sucked with a needle at a rate of 10 μL / min for 90 seconds, and the contact angle is measured every second (total 90 times). Next, from the time when the contact angle was stabilized, an average value was calculated for a total of 20 contact angles, which were set as receding contact angles (°).

  From the value of the receding contact angle of the resist film formed from the radiation sensitive resin composition immediately after preparation and after storage for 30 days, the storage stability was evaluated as follows. That is, when the fluctuation between the two values is within 3%, “◯” is given, and when it exceeds 3% and 5% or less, “Δ” is given, and when it exceeds 5%, “X” is given.

[sensitivity]
About each radiation sensitive resin composition of the said Example and comparative example, the optimal exposure amount was measured with the following procedure immediately after preparation and after 30 days preservation | save, and it was set as each "sensitivity."

(1) Formation of antireflection layer A composition for forming a lower antireflection film (trade name “ARC66”, manufactured by Nissan Chemical Co., Ltd.) on a 12-inch silicon wafer surface, a semiconductor manufacturing apparatus (model name “Lithius Pro-i”), Spin coating using Tokyo Electron). Next, PB (205 ° C., 60 seconds) was performed to form an antireflection layer having a thickness of 105 nm.
(2) Formation of photoresist layer Thereafter, the photoresist composition was spin-coated using a semiconductor manufacturing apparatus (model name “CLEAN TRACK ACT12”, manufactured by Tokyo Electron Ltd.). Then, PB (110 ° C., 60 seconds) and cooling (23 ° C., 30 seconds) were performed to form a 100 nm-thick photoresist layer.
(3) Formation of resist pattern Next, using an ArF immersion exposure apparatus (trade name “S610C”, manufactured by NIKON), the target size is 48 nm line / 96 nm under the optical conditions of NA: 1.30 and Crosspore. Exposure was through a pitch mask. Thereafter, PEB (95 ° C., 60 seconds) and cooling (23 ° C., 30 seconds) were performed on a hot plate of a semiconductor manufacturing apparatus (model name “Lithius Pro-i”, manufactured by Tokyo Electron Ltd.). Next, paddle development (10 seconds) was performed using a 2.38% tetramethylammonium hydroxide aqueous solution as a developer with a GP nozzle of the developing cup, and rinsed with ultrapure water. Thereafter, the silicon wafer for evaluation on which a resist pattern (line and space pattern) of 48 nm line / 96 nm pitch was formed was obtained by spin-drying by shaking off at 2000 rpm for 15 seconds. At this time, in the mask dimension of 48 nm line / 96 nm pitch, the exposure amount for forming a pattern of 48 nm line / 96 nm pitch was determined as the optimum exposure amount, and this was set as “sensitivity”.

  From the value of “sensitivity” obtained for the radiation-sensitive resin composition immediately after preparation and after storage for 30 days, storage stability was evaluated as follows. That is, when the fluctuation between the two values was 0% or more and 3% or less, “◯” was evaluated, and when it exceeded 3% and less than 5%, “Δ” was evaluated, and when it was 5% or more, “X” was evaluated.

  Each metal content obtained by the above measurement, converted metal content Q (mass ppb) calculated by the above formula, water content, and each evaluation result regarding the storage stability are shown in Table 1 below.

  From the results of Table 1 above, when the total content of metals contained in the radiation-sensitive resin composition is 30 mass ppb or less, it is excellent in storage stability with respect to particles in liquid, receding contact angle and sensitivity. Indicated. On the other hand, it was also shown that when the total content of metals exceeds 30 mass ppb, the storage stability for each characteristic deteriorates.

The radiation-sensitive resin composition of the present invention can be suitably used as a chemically amplified resist for manufacturing semiconductor devices, particularly a resist for immersion exposure.

Claims (6)

[A] a fluoropolymer having a structural unit (f) containing a base-dissociable group and a structural unit (p) containing an acid-dissociable group, and [C] a radiation-sensitive acid generator,
The structural unit (f) is represented by the following formula (1):
A radiation-sensitive resin composition having a total metal content of 20 mass ppb or less.

(In Formula (1), R is a hydrogen atom, a fluorine atom, or a monovalent chain hydrocarbon group having 1 to 4 carbon atoms, and the monovalent chain hydrocarbon group having 1 to 4 carbon atoms is at least 1; E is an (n + 1) -valent linking group, Rf is a monovalent chain hydrocarbon group which may have a fluorine atom, or a monovalent aromatic carbon group. A hydrogen group, n is an integer of 1 to 3. When n is 2 or 3, each Rf independently has the above definition.) The converted metal content represented by the following formula Q is 20 mass ppb or less, The radiation sensitive resin composition of Claim 1.
Q = 3.2 × S + M (wherein Q is the converted metal content (mass ppb), M is the metal content (mass ppb), and S is the total content of sodium, magnesium and iron (mass) ppb).)   The radiation sensitive resin composition according to claim 1 or 2, wherein the metal contains sodium, magnesium or iron, and each content of sodium, magnesium or iron is 3 mass ppb or less. The radiation sensitive resin composition according to claim 1, wherein the structural unit (f) is represented by the following formula (1-1).

(In Formula (1-1), R is a hydrogen atom, a fluorine atom, or a monovalent chain hydrocarbon group having 1 to 4 carbon atoms, and the monovalent chain hydrocarbon group having 1 to 4 carbon atoms is May be substituted with at least one halogen atom, Rf is a monovalent chain hydrocarbon group or aromatic hydrocarbon group optionally substituted with a fluorine atom, and ^Ra is substituted with a substituent; A divalent chain organic group or an aromatic hydrocarbon group which may be substituted, and X is a divalent hydrocarbon group substituted with at least one fluorine atom.) The radiation sensitive resin composition according to any one of claims 1 to 4, wherein the structural unit (p) is represented by the following formula (4).

(In Formula (4), R is a hydrogen atom, a fluorine atom, or a monovalent chain hydrocarbon group having 1 to 4 carbon atoms, and the monovalent chain hydrocarbon group having 1 to 4 carbon atoms is at least 1; Y may be a group represented by the following formula (Y-1).

(In the formula (Y-1), R ^p1 is a monovalent chain hydrocarbon group having 1 to 4 carbon atoms or a monovalent aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms. R ^p2 and R ^p3 Are each independently a monovalent chain hydrocarbon group having 1 to 4 carbon atoms or a monovalent aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms, or R ^p2 and R ^p3 are bonded to each other. , Together with the carbon atoms to which each is bonded, a divalent aliphatic cyclic hydrocarbon group having 4 to 20 carbon atoms is formed.)   [A] The method for producing a radiation-sensitive resin composition according to any one of claims 1 to 5, further comprising a step of filtering the solution containing the fluoropolymer with a nylon filter having a pore diameter of 10 nm or less.