JP2012215722A - Composition for forming overlay film for liquid immersion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for forming an overlay film for a liquid immersion process, the composition excellent in adhesiveness (peeling resistance) to a substrate.SOLUTION: The composition for forming an overlay film for a liquid immersion process contains a polymer component (A) having a repeating unit (a) including a plurality of carboxyl groups, and a solvent (B). Specifically, the repeating unit having a plurality of carboxyl groups is expressed by formula (a1).

Description

  The present invention relates to a composition for forming a liquid immersion upper layer film, and more particularly to a composition for forming a liquid immersion upper layer film used for forming an upper layer film for protecting a resist film during liquid immersion exposure.

  Conventionally, chemically amplified resists are used in the field of microfabrication represented by the manufacture of integrated circuit elements. In chemically amplified resists, acid is generated in the exposed area by irradiation with short-wave radiation (for example, excimer laser), and the dissolution rate of the alkali developer in the exposed area and unexposed area due to the reaction using the acid as a catalyst. As a result, a resist pattern is formed on the substrate.

  In such a chemically amplified resist, as a method of forming a finer resist pattern, exposure is performed by filling a space between the lens and the resist film with an immersion medium (for example, pure water or a fluorine-based inert liquid). The use of immersion exposure (liquid immersion lithography) is expanding. According to this immersion exposure method, it is possible to increase the numerical aperture (NA) of the lens, and even when the NA is increased, there is an advantage that the depth of focus is not easily lowered and high resolution can be obtained. is there.

  In resist pattern formation by the immersion exposure method, it is required to suppress dissolution of the resist coating composition into the immersion medium and pattern defects due to droplets remaining on the coating surface, and to improve the scanning speed. . As a technique for satisfying the requirement, it has been proposed to provide a protective film between the resist film and the immersion medium (see Patent Document 1). In these Patent Documents 1, a water-insoluble and alkali-soluble polymer is used to form a protective film on a resist film, whereby the resist film composition is eluted due to the water repellency of the protective film during immersion exposure. In addition, the protective film is removed from the surface of the resist film by suppressing the pattern defects and the like, and dissolving the protective film in the developer in the subsequent alkali development step. Patent Document 1 discloses that a repeating unit having one carboxyl group is used as one of the constituent components of the polymer.

International Publication No. 2009/41270

  However, the above-mentioned conventional composition for forming an upper layer film for liquid immersion has a problem in that the adhesiveness to the substrate (resistance to peeling) is not sufficient.

  The present invention has been made in view of the above problems, and an object thereof is to provide a composition for forming a liquid immersion upper layer film that is excellent in adhesiveness (resisting resistance) to a substrate.

  As a result of intensive studies to solve the problems of the prior art as described above, the present inventors have used a composition for forming a liquid immersion upper layer film containing a polymer component having a repeating unit containing a plurality of carboxyl groups. The present inventors have found that the above problems can be solved, and have completed the present invention. Specifically, the following composition for forming a liquid immersion upper film is provided.

[1] A composition for forming a liquid immersion upper layer film comprising a polymer component (A) having a repeating unit (a) containing a plurality of carboxyl groups and a solvent (B).
[2] The composition for forming a liquid immersion upper layer film according to [1], wherein the repeating unit containing a plurality of carboxyl groups is represented by the following formula (a1).

（上記式（ａ１）中、Ｑは（ｍ＋１）価の有機基であり、Ｒは、それぞれ独立に水素原子、メチル基またはトリフルオロメチル基を示し、ｍは、２〜４の整数である。）
［３］前記式（ａ１）において、Ｑが、炭素数１〜１０の（ｍ＋１）価の脂肪族炭化水素基、または炭素数３〜１０の（ｍ＋１）価の脂環式炭化水素基である、前記［１］または［２］に記載の液浸上層膜形成用組成物。
［４］重合体成分（Ａ）が、スルホ基を有する繰り返し単位（ｓ）を有する、前記［１］〜［３］のいずれかに記載の液浸上層膜形成用組成物
［５］重合体成分（Ａ）が、フッ素原子を有する繰り返し単位（ｆ）を有する、前記［１］〜［４］のいずれかに記載の液浸上層膜形成用組成物。
［６］前記［１］〜［５］のいずれかに記載の液浸上層膜形成用組成物を用いて形成された液浸上層膜。
［７］基板上にフォトレジスト組成物を塗布してフォトレジスト膜を形成する工程（１）と、前記［１］〜［６］のいずれか一項に記載の液浸上層膜形成用組成物を前記フォトレジスト膜上に塗布して前記フォトレジスト膜上に上層膜を形成する工程（２）と、前記上層膜上に液浸媒体を配し、所定のパターンを有するマスクおよび液浸液体を通過させた露光光を、前記上層膜及び前記フォトレジスト膜に照射することによって、前記上層膜及び前記フォトレジスト膜を露光する工程（３）と、露光された前記上層膜及び前記フォトレジスト膜を現像液で現像する工程（４）と、を備えるレジストパターン形成方法。

(In the above formula (a1), Q is an (m + 1) -valent organic group, R independently represents a hydrogen atom, a methyl group or a trifluoromethyl group, and m is an integer of 2 to 4. )
[3] In the formula (a1), Q is an (m + 1) -valent aliphatic hydrocarbon group having 1 to 10 carbon atoms or an (m + 1) -valent alicyclic hydrocarbon group having 3 to 10 carbon atoms. The composition for forming a liquid immersion upper layer film according to [1] or [2].
[4] The composition for forming an upper liquid immersion film according to any one of [1] to [3], wherein the polymer component (A) has a repeating unit (s) having a sulfo group [5] Polymer The composition for forming an immersion upper layer film according to any one of [1] to [4], wherein the component (A) has a repeating unit (f) having a fluorine atom.
[6] A liquid immersion upper film formed using the liquid immersion upper film forming composition according to any one of [1] to [5].
[7] A step (1) of forming a photoresist film by applying a photoresist composition on a substrate, and the composition for forming an immersion upper layer film according to any one of [1] to [6] A step (2) of forming an upper layer film on the photoresist film by applying an immersion medium on the photoresist film, an immersion medium is disposed on the upper layer film, and a mask having a predetermined pattern and an immersion liquid are provided. The step (3) of exposing the upper layer film and the photoresist film by irradiating the upper layer film and the photoresist film with the passed exposure light, and the exposed upper layer film and the photoresist film And a step (4) of developing with a developer.

  According to the composition for forming an upper layer film for immersion according to the present invention (hereinafter, also simply referred to as “the composition for forming an upper layer film”), the composition for forming an upper layer film containing a polymer component having a specific repeating unit. By using a thing, it is excellent in adhesiveness (separation resistance) with a board | substrate.

Hereinafter, the present invention will be described in detail. In the present specification, “(meth) acryl” means acrylic and methacrylic.
The composition for forming a liquid immersion upper layer film of the present invention (hereinafter also referred to as a composition for forming an upper layer film) includes a polymer component (A) and a solvent (B), and all repeating units of the polymer component (A). At least a part of the repeating unit (a) having a plurality of carboxyl groups. Hereinafter, the composition for forming a liquid immersion upper layer film of the present invention will be described in detail.

[Polymer component (A)]
[Repeating unit having a plurality of carboxyl groups (a)]
The polymer component in the present invention includes a repeating unit (a) having a plurality of carboxyl groups (hereinafter, also referred to as “repeating unit (a)) as a part of all repeating units.
Examples of the repeating unit having a plurality of carboxyl groups include a repeating unit represented by the following formula (a1).

  In the above formula (a1), Q is an (m + 1) -valent organic group, R independently represents a hydrogen atom, a methyl group or a trifluoromethyl group, and m is an integer of 2 to 4. Accordingly, 2 to 4 carboxyl groups are introduced into the repeating unit (a1).

In general formula (a1), Q is an (m + 1) -valent organic group, preferably an (m + 1) -valent organic group having 1 to 30 carbon atoms, and an (m + 1) -valent organic group having 1 to 20 carbon atoms. It is more preferably a group, and further preferably an (m + 1) -valent organic group having 1 to 10 carbon atoms.
Examples of the (m + 1) -valent organic group having 1 to 30 carbon atoms include an (m + 1) -valent hydrocarbon group having 1 to 30 carbon atoms, an (m + 1) -valent halogenated hydrocarbon group having 1 to 30 carbon atoms, and oxygen An (m + 1) -valent organic group containing at least one atom selected from the group consisting of an atom, a sulfur atom and a nitrogen atom can be given.

  Examples of the (m + 1) -valent hydrocarbon group having 1 to 30 carbon atoms include a linear or branched (m + 1) -valent hydrocarbon group having 1 to 30 carbon atoms and an (m + 1) -valent fat having 3 to 30 carbon atoms. Examples thereof include a cyclic hydrocarbon group and an (m + 1) -valent aromatic hydrocarbon group having 6 to 30 carbon atoms.

  The linear or branched (m + 1) -valent hydrocarbon group having 1 to 30 carbon atoms is preferably a linear or branched (m + 1) -valent hydrocarbon group having 1 to 20 carbon atoms, 10 to 10 linear or branched (m + 1) -valent hydrocarbon groups are more preferable. Preferable specific examples of the linear or branched (m + 1) -valent hydrocarbon group having 1 to 30 carbon atoms include, for example, methane, ethane, propane, butane, 2-methylpropane, pentane, 2-methylbutane, 2 , 2-dimethylpropane, hexane, heptane, octane, nonane, decane, etc., a structure in which (m + 1) hydrogen atoms are removed from a chain hydrocarbon having 1 to 20 carbon atoms.

The (m + 1) -valent alicyclic hydrocarbon group having 3 to 30 carbon atoms is preferably an (m + 1) -valent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and (m + 1) having 3 to 10 carbon atoms. A valent alicyclic hydrocarbon group is more preferred. Preferable specific examples of the (m + 1) -valent alicyclic hydrocarbon group having 3 to 30 carbon atoms include, for example, cyclobutane, cyclopentane, cyclohexane, bicyclo [2.2.1] heptane, and bicyclo [2.2. 2] Hydrogen atoms from alicyclic hydrocarbons having 3 to 20 carbon atoms such as octane, tricyclo [5.2.1.0 ^2,6 ] decane, tricyclo [3.3.1.1 ^3,7 ] decane, etc. A hydrocarbon group having a structure in which (m + 1) pieces are removed may be mentioned.

  As the C6-C30 aromatic hydrocarbon group, a (m + 1) -valent aromatic hydrocarbon group having 6 to 20 carbon atoms is preferable, and a (m + 1) -valent aromatic hydrocarbon group having 6 to 10 carbon atoms. Is more preferable. Preferable specific examples of the (m + 1) -valent alicyclic hydrocarbon group having 6 to 30 carbon atoms include a hydrocarbon group having a structure in which (m + 1) hydrogen atoms are removed from an aromatic hydrocarbon such as benzene and naphthalene. Etc.

  As the (m + 1) -valent halogenated hydrocarbon group having 1 to 30 carbon atoms, a part or all of the hydrogen atoms of the aforementioned (m + 1) -valent hydrocarbon group having 1 to 30 carbon atoms is a halogen atom such as a fluorine atom. And a group substituted with.

  Examples of the (m + 1) -valent organic group having 1 to 30 carbon atoms including an oxygen atom include a hydrogen atom, a carbon atom, and an organic group composed of an oxygen atom, and among them, an ether bond, a carbonyl group or an ester group, Preferred examples include (m + 1) -valent organic groups having a total carbon number of 1 to 30 consisting of hydrocarbon groups, and the total carbon number is preferably 1 to 20, and more preferably 1 to 10. .

  Examples of the (m + 1) -valent organic group having 1 to 30 carbon atoms containing a sulfur atom include an organic group consisting of a hydrogen atom, a carbon atom, and a sulfur atom. Among them, a thioether bond, a thiocarbonyl group, or a thioester group The (m + 1) -valent organic group having 1 to 30 carbon atoms, which is composed of a hydrocarbon group, can be preferably mentioned, and the total carbon number is preferably 1 to 20 and more preferably 1 to 10. preferable.

  Examples of the organic group having 1 to 30 carbon atoms including a nitrogen atom include an organic group consisting of a hydrogen atom, a carbon atom, and a nitrogen atom, and specifically, hydrogen from imidazole, triazole, benzimidazole, benztriazole, and the like. An organic group having a structure in which (m + 1) atoms are removed may be mentioned.

  Examples of the organic group having 1 to 30 carbon atoms including an oxygen atom and a nitrogen atom include an organic group composed of a hydrogen atom, a carbon atom, an oxygen atom, and a nitrogen atom. Specifically, an oxazole group, an oxadiazole An organic group having a structure in which (m + 1) hydrogen atoms are removed from a group, a benzoxazole group, a benzoxadiazole group, and the like.

  Examples of the repeating unit represented by the general formula (a1) include the repeating units represented by the following general formula (a1-1) or (a1-2).

（上記式（ａ１−１）中、Ｑ^１は、単結合または炭素数１〜３０の（ｎ１＋２）価の炭化水素基を示し、Ｅは、単結合またはメチレン基であり、Ｒは、それぞれ独立に水素原子、メチル基またはトリフルオロメチル基を示し、ｎ１は１または２である。上記式（ａ１−２）中、Ｑ^２は、単結合または炭素数１〜１０の２価の炭化水素基を示し、Ｒ^１、Ｒ^２は、それぞれ独立して水素原子、フッ素原子又は炭素数１〜５の１価の炭化水素基であり、Ｒは、それぞれ独立に水素原子、メチル基またはトリフルオロメチル基を示し、ａは、０又は１である。ｂは、０〜２の整数である。）

(In the above formula (a1-1), Q ¹ represents a single bond or a (n1 + 2) valent hydrocarbon group having 1 to 30 carbon atoms, E represents a single bond or a methylene group, and R represents an independent group. a hydrogen atom, a methyl group or a trifluoromethyl group, n1 is 1 or 2. in the formula (a1-2), ^{Q 2} is a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms R ¹ and R ² are each independently a hydrogen atom, a fluorine atom or a monovalent hydrocarbon group having 1 to 5 carbon atoms, and R is independently a hydrogen atom, a methyl group or trifluoromethyl. A represents 0 or 1. b represents an integer of 0 to 2.)

（上記式中、Ｒは、それぞれ独立に水素原子、メチル基またはトリフルオロメチル基を示す。） Specific examples of the repeating unit (a1-1) include those represented by the following formula.

(In the above formula, each R independently represents a hydrogen atom, a methyl group or a trifluoromethyl group.)

（上記式中、Ｒは、それぞれ独立に水素原子、メチル基またはトリフルオロメチル基を示す。）
前記重合体成分（Ａ）における繰り返し単位（ａ）の含有量は、重合体成分（Ａ）が有する全繰り返し単位を１００モル％として、通常、０．１〜３０モル％であり、好ましくは０．５〜２０モル％である。繰り返し単位（ａ）の含有量がある上記範囲であると、Ｂｌｏｂ欠陥を抑制でき、また、下地となるレジスト層に影響しにくく、さらに基板との密着性に優れる。 Specific examples of the repeating unit (a1-2) include the following formulas.

(In the above formula, each R independently represents a hydrogen atom, a methyl group or a trifluoromethyl group.)
The content of the repeating unit (a) in the polymer component (A) is usually from 0.1 to 30 mol%, preferably 0, based on 100 mol% of all repeating units of the polymer component (A). .5 to 20 mol%. When the content of the repeating unit (a) is within the above range, Blob defects can be suppressed, the resist layer as a base is hardly affected, and the adhesion to the substrate is excellent.

[Repeating unit having sulfo group (s)]
The polymer component in the present invention includes a repeating unit (s) having a sulfo group (hereinafter, also referred to as “repeating unit (s)) as a part of all the repeating units.
Although it does not specifically limit as a repeating unit which has a sulfo group, The repeating unit represented by the following general formula (S-1) or (S-2) can be mentioned.

［一般式（Ｓ−１）及び（Ｓ−２）において、Ｒは、それぞれ独立に水素原子、メチル基またはトリフルオロメチル基を示し、Ｒ^ｓ１は、それぞれ独立に単結合、炭素数１〜６の直鎖状若しくは分岐状の２価の炭化水素基、炭素数４〜１２の２価の脂環式炭化水素基、または炭素数６〜１２の２価の芳香族炭化水素基を示す。］

[In General Formulas (S-1) and (S-2), R each independently represents a hydrogen atom, a methyl group or a trifluoromethyl group, and R ^s1 each independently represents a single bond, having 1 to 6 carbon atoms. A linear or branched divalent hydrocarbon group, a divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 12 carbon atoms. ]

Examples of the linear or branched divalent hydrocarbon group having 1 to 6 carbon atoms of R ^{s1 in} the general formulas (S-1) and (S-2) include a methylene group and an ethylene group; Propylene groups such as 1,3-propylene group and 1,2-propylene group; tetramethylene group, pentamethylene group, hexamethylene group, 1-methyl-1,3-propylene group, 2-methyl-1,3-propylene group 2-methyl-1,2-propylene group, 1-methyl-1,4-butylene group, 2-methyl-1,4-butylene group, ethylidene group, propylidene group, 2-propylidene group, and the like. .

Examples of the divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms of R ^s1 include a monocyclic hydrocarbon group and a bridged cyclic hydrocarbon group.
Examples of the monocyclic hydrocarbon group include a cyclobutylene group such as a 1,3-cyclobutylene group, a cyclopentylene group such as a 1,3-cyclopentylene group, and a cyclohexylene group such as a 1,4-cyclohexylene group. And a cycloalkylene group having 4 to 12 carbon atoms such as a cyclooctylene group such as 1,5-cyclooctylene group.
Examples of the bridged cyclic hydrocarbon group include a norbornylene group such as a 1,4-norbornylene group and a 2,5-norbornylene group, an adamantylene group such as a 1,5-adamantylene group, and a 2,6-adamantylene group. 2-4 cyclic hydrocarbon groups having 4 to 12 carbon atoms.
The divalent aromatic hydrocarbon group having 6 to 12 carbon atoms of the R ^s1, for example, a phenylene group, such as an arylene group such as a tolylene group.

  Among these, in the general formula (S-1), a single bond, a linear or branched divalent hydrocarbon group having 1 to 6 carbon atoms, or a divalent aromatic hydrocarbon having 6 to 12 carbon atoms. Group is preferred, and a single bond, a methylene group or a phenylene group is particularly preferred. In the general formula (S-2), a linear or branched divalent hydrocarbon group having 1 to 6 carbon atoms is preferable, and a 2-methylpropane-2,3-diyl group is particularly preferable.

  Specific examples of the repeating unit (s) include those represented by the following formula.

（上記式においてＲは水素原子、メチル基またはトリフルオロメチル基を示す。）

(In the above formula, R represents a hydrogen atom, a methyl group or a trifluoromethyl group.)

  The content of the repeating unit (s) in the polymer component (A) is usually 1 to 20 mol%, preferably 1 to 10 mol, based on 100 mol% of all repeating units of the polymer component (A). Mol%. When the content of the repeating unit (s) is within the above range, blob defects can be suppressed and the resist layer serving as a base is hardly affected.

[Repeating unit (f)]
The repeating unit (f) has a fluorine atom. Specifically, the repeating unit (f1) represented by the following formula (f-1) and the repeating unit represented by the following formula (f-2) A unit (f2) can be mentioned.

（上記式（ｆ−１）中、Ｒ^ｆ１は２価の連結基であり、上記式（ｆ−２）中、Ｒ^ｆ２はフッ素原子を含有する炭素数１〜１０の直鎖状若しくは分岐状の１価の炭化水素基又は炭素数３〜１０の１価の脂環式炭化水素基である。Ｒは、それぞれ独立に水素原子、メチル基またはトリフルオロメチル基を示す。）

(In the above formula (f-1), R ^f1 is a divalent linking group, and in the above formula (f-2), R ^f2 is a linear or branched chain having 1 to 10 carbon atoms containing a fluorine atom. And a monovalent alicyclic hydrocarbon group having 3 to 10 carbon atoms, each independently representing a hydrogen atom, a methyl group or a trifluoromethyl group.)

As the divalent linking group for R ^{f1 in} the above formula (f-1), a linear or branched divalent hydrocarbon group having 1 to 6 carbon atoms or a divalent fat having 4 to 12 carbon atoms. It may be mentioned cyclic hydrocarbon group, the specific examples illustrated by L ² in the formula (3) can be applied as it is. In addition, the methylene group (—CH ₂ —) in the hydrocarbon group and alicyclic hydrocarbon group may be substituted with an oxygen atom, a carbonyl group, or an ester group. R ^f1 is preferably a linear or branched divalent hydrocarbon group having 1 to 3 carbon atoms, a divalent group containing a norbornene skeleton, or a divalent group containing an adamantane skeleton.

  Specific examples of the repeating unit (f1) include repeating units represented by the following formulas (f1-1) to (f1-6).

（上記式中、Ｒは、それぞれ独立に水素原子、メチル基またはトリフルオロメチル基を示す。）

(In the above formula, each R independently represents a hydrogen atom, a methyl group or a trifluoromethyl group.)

The repeating unit (f2) is a monovalent linear or branched hydrocarbon group containing a fluorine atom of R ^f2 having 2 to 8 carbon atoms or a monovalent alicyclic hydrocarbon. A group having 4 to 8 carbon atoms is more preferable.

  Specific examples of the repeating unit (f-2) include those represented by the following formula.

（上記式中、Ｒは、それぞれ独立に水素原子、メチル基またはトリフルオロメチル基を示す。）
前記重合体成分（Ａ）における繰り返し単位（ｆ）の含有量は、重合体成分（Ａ）が有する全繰り返し単位を１００モル％として、好ましくは、５０〜９７モル％であり、より好ましくは６０〜９５モル％である。繰り返し単位（ｆ）の含有量がある上記範囲であると、上層膜表面と水滴との接触角を良好にすることができ、特に後退接触角を高くすることができる。

(In the above formula, each R independently represents a hydrogen atom, a methyl group or a trifluoromethyl group.)
The content of the repeating unit (f) in the polymer component (A) is preferably 50 to 97 mol%, more preferably 60, based on 100 mol% of all repeating units of the polymer component (A). -95 mol%. When the content of the repeating unit (f) is within the above range, the contact angle between the surface of the upper film and the water droplet can be improved, and in particular, the receding contact angle can be increased.

  In addition to the above repeating units, the polymer component in the present invention contains a repeating unit (n1) represented by the following formula (n-1) for the purpose of improving the solubility in an alkali developer. You can also.

（式（ｎ−１）中、Ｒ^ｎ２は、炭素数１〜２０のフルオロアルキル基である。Ｒ^ｎ１は、上記式（ｆ−１）のＲ^ｆ１と同義であり、Ｒは、それぞれ独立に水素原子、メチル基またはトリフルオロメチル基を示す。）

(In formula (n-1), ^Rn2 is a C1-C20 fluoroalkyl group. ^Rn1 is synonymous with ^Rf1 of the said Formula (f-1), and R is each independently. Represents a hydrogen atom, a methyl group or a trifluoromethyl group.)

  In addition to the above repeating units, the polymer component in the present invention may contain, for example, a repeating unit (n2) represented by the following formula (n-2) for the purpose of improving water repellency. .

［一般式（ｎ−２）において、Ｒ^ｎ３は炭素数１〜２０の直鎖状若しくは分岐状のアルキル基、又は炭素数４〜２０の１価の脂環式炭化水素基の有する水素原子の一部または全部がフッ素原子で置換された基を示し、Ｒは、それぞれ独立に水素原子、メチル基またはトリフルオロメチル基を示す。］

[In General Formula (n-2), R ⁿ³ represents a hydrogen atom of a linear or branched alkyl group having 1 to 20 carbon atoms or a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms. R represents a group partially or entirely substituted with a fluorine atom, and each R independently represents a hydrogen atom, a methyl group or a trifluoromethyl group. ]

  Examples of the monomer for obtaining the repeating unit (n2) include compounds represented by the following formulas.

  In addition to the above repeating units, the polymer component in the present invention may contain, for example, a repeating unit having one carboxyl group for the purpose of improving the solubility in an alkali developer, or For the purpose of controlling the molecular weight, glass transition point, solubility in a solvent, etc., a repeating unit having an acid-dissociable group that can be eliminated by the action of an acid or other repeating units can be contained.

  The repeating unit having one carboxyl group is represented by the repeating unit represented by the following formula (C-1), the repeating unit represented by the following formula (C-2), and the following formula (C-3). Any one of at least one repeating unit selected from repeating units may be mentioned.

（上記一般式（Ｃ−１）〜（Ｃ−３）において、Ｒは、それぞれ独立に水素原子、メチル基またはトリフルオロメチル基を示す。Ｒ^ｃ１及びＲ^ｃ２は、それぞれ独立に、炭素数１〜６の直鎖状若しくは分岐状の２価の炭化水素基、炭素数４〜１２の２価の脂環式炭化水素基、または炭素数６〜１２の２価の芳香族炭化水素基を示す。）

(In the above general formulas (C-1) to (C-3), R each independently represents a hydrogen atom, a methyl group or a trifluoromethyl group. R ^c1 and R ^c2 each independently represent 1 carbon atom. Represents a -6 linear or branched divalent hydrocarbon group, a divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 12 carbon atoms. .)

In the general formulas (C-1) and (C-2), a linear or branched divalent hydrocarbon group having 1 to 6 carbon atoms of R ^c1 and R ^c2 and a divalent hydrocarbon having 4 to 12 carbon atoms. For the alicyclic hydrocarbon group and the divalent aromatic hydrocarbon group having 6 to 12 carbon atoms, the description of R ^s1 in the general formulas (S-1) and (S-2) can be applied as it is. it can.

  Specific examples of the repeating unit represented by the formula (C-1) or (C-2) include those represented by the following formula.

（上記各式において、Ｒは、それぞれ独立に水素原子、メチル基またはトリフルオロメチル基を示す。）

(In the above formulas, each R independently represents a hydrogen atom, a methyl group or a trifluoromethyl group.)

[Polymer (A1)]
When the polymer component contains the polymer (A1), the content of the repeating unit (a) in the polymer (A1) is preferably 100% by mole based on all the repeating units of the polymer (A1). It is 1-50 mol%, More preferably, it is 3-20 mol%. When the content of the repeating unit (a) is 1 mol% or more, the number of defects can be reduced by reducing the amount of undissolved polymer (A1), and when the content is 50 mol% or less, the polymer ( The hydrophilicity of A1) does not become too high, and the water repellency of the upper layer film can be improved.

  The polymer (A1) may have a repeating unit other than the repeating unit (a) among those exemplified above as the repeating unit that may be contained in the polymer component. Specific examples include the repeating unit (s) and the repeating unit (f).

  The content of the polymer (A1) is preferably 60 to 95% by mass, based on 100% by mass of all the polymer components contained in the composition for forming a liquid immersion upper layer film. More preferably, it is 90 mass%. When the content of the polymer (A1) is 60% by mass or more, the dissolution rate of the upper layer film in the alkaline developer can be further increased, and defects due to the undissolved portion of the upper layer film can be reduced. . Further, when it is 95% by mass or less, in the polymer component, when the polymer (A2) described later is included, the high water repellency of the polymer (A2) is easily maintained, and the receding contact angle is maintained high in the upper layer film. can do.

[Other polymers]
[Polymer (A2)]
In the composition for forming an upper layer film of the present invention, a polymer (A2) having higher water repellency than the polymer (A1) is used as a polymer (hereinafter also referred to as other polymer) different from the polymer (A1). ). In this case, the polymer (A2) is likely to be localized on the surface of the upper layer film, and the water repellency of the polymer (A2) can improve the contact angle between the surface of the upper layer film and the water droplets. The contact angle can be increased. On the other hand, the polymer (A1) is likely to be localized on the interface side between the resist film and the upper film, and defects are suppressed by the presence of the mixing layer formed at the interface, regardless of the type of resist. A rectangular resist shape can be obtained (dependence of the resist shape can be reduced). Moreover, when a polymer (A1) has a repeating unit (c), the developing solution solubility in a mixing layer can be improved more, and the inhibitory effect of a defect can be improved further.

  The polymer (A2) preferably has a fluorine atom content (mass%) higher than that of the polymer (A1). The polymer (A2) preferably includes the repeating unit (f). Specifically, (i) a homopolymer of the repeating unit (f1), (ii) the repeating unit (f1) and Examples include a copolymer with the above repeating unit (f2), a copolymer with (iii) a repeating unit in which a polymerizable unsaturated bond in alkyl (meth) acrylate is cleaved, and the above repeating unit (f1). it can. More specifically, for example, methacrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester homopolymer, methacrylic acid (2,2,2-trifluoro) Ethyl) ester / methacrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester copolymer, methacrylic acid (2,2,2-trifluoroethyl) ester Methacrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester copolymer, butyl methacrylate / methacrylic acid (1,1,1-trifluoro-2-tri Fluoromethyl-2-hydroxy-4-pentyl) ester copolymer, lauryl methacrylate / methacrylic acid (1,1,1-trifluoro) 2-trifluoromethyl-2-hydroxy-4-pentyl) ester copolymer, methacrylic acid (1,1,1,3,3,3, -hexafluoro-2-propyl) ester / methacrylic acid (1,1 , 1-trifluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester copolymer and the like. These may be used individually by 1 type and may be used in combination of 2 or more type.

  The content of the repeating unit (f) in the polymer (A2) is preferably 10 to 100 mol%, more preferably 20 to 100, based on 100 mol% of all repeating units of the polymer (A2). Mol%. When the content of the repeating unit (f) is 10 mol% or more, the solubility of the polymer (A2) in the alkali developer is not too low, and the effect of suppressing undissolved defects is high.

  The content of the polymer (A2) is preferably 5 to 40% by mass, based on 100% by mass of the entire polymer component (A) contained in the upper layer film-forming composition. More preferably, it is -30 mass%. By setting it as the said range, a receding contact angle can be made high moderately and a defect can be suppressed more.

Moreover, the said polymer component (A) may contain polymers other than the said polymer (A2) as another polymer. Specifically, for example, as the other polymer, the polymer (A2) and a polymer (A3) having a fluorine atom content lower than that of the polymer (A2) and higher than that of the polymer (A1). The form to contain can be mentioned. Specific examples of the polymer (A3) include a copolymer (A3) of an alkali-soluble group such as the repeating unit (f1) and the repeating unit (s).
In addition, this polymer component does not necessarily need to contain "other polymer", and may be comprised with the said polymer (A1) independent.

  The method for producing each polymer contained as the polymer component (A) is not particularly limited. For example, one or more corresponding radicals in a polymerization solvent in the presence of an appropriately selected initiator or chain transfer agent. It can be produced by radical polymerization of a polymerizable monomer.

  Examples of the polymerization solvent include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, ethylene glycol, diethylene glycol, and propylene glycol; cyclic ethers such as tetrahydrofuran and dioxane; ethylene Glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl Alkyl ethers of polyhydric alcohols such as ethers; alkyl ether acetates of polyhydric alcohols such as ethylene glycol ethyl ether acetate, diethylene glycol ethyl ether acetate, propylene glycol ethyl ether acetate, propylene glycol monomethyl ether acetate; aromas such as toluene and xylene Group hydrocarbons; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, 4-hydroxy-4-methyl-2-pentanone, diacetone alcohol; ethyl acetate, butyl acetate, methyl 2-hydroxypropionate, 2- Ethyl hydroxy-2-methylpropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, - hydroxy-3-methylbutanoate, methyl 3-methoxypropionate, 3-methoxypropionate, ethyl 3-ethoxy ethyl propionate, it can be mentioned esters such as 3-ethoxymethyl propionate. Among these, cyclic ethers, polyhydric alcohol alkyl ethers, polyhydric alcohol alkyl ether acetates, ketones, and esters are preferable. In addition, these solvents may be used individually by 1 type, and may be used in combination of 2 or more type.

The weight average molecular weight (hereinafter also referred to as “Mw”) of each polymer contained as the polymer component (A) is preferably 2,000 to 100,000, more preferably 2,500. 50,000 to 50,000, more preferably 3,000 to 20,000. When this Mw is less than 2,000, the water resistance and mechanical properties as the upper layer film may be remarkably lowered. On the other hand, when it exceeds 100,000, the solubility in the solvent may be remarkably deteriorated.
Further, the ratio (Mw / Mn) between Mw and the number average molecular weight (hereinafter also referred to as “Mn”) of each polymer is preferably 1 to 5, and more preferably 1 to 3. In the present specification, “weight average molecular weight” and “number average molecular weight” are values in terms of polystyrene measured by gel permeation chromatography (GPC).

The polymer component (A) is preferably as less as possible as impurities such as halogen ions and metals. By reducing the impurities, the coating properties as the upper layer film and the uniform solubility in the alkali developer can be further improved. Can do.
Furthermore, as a method for purifying the polymer contained in the polymer component (A), for example, chemical purification methods such as washing with water, liquid-liquid extraction, etc., and these chemical purification methods and ultrafiltration, centrifugation, etc. The combination with a physical purification method etc. can be mentioned.

  The polymer component (A) in the present invention can form an upper layer film (protective film) that is stable against an immersion medium (immersion liquid) such as water upon irradiation with radiation, that is, an upper layer film having high water resistance. It can be dissolved in a developer used for forming a resist pattern. Here, “stable against immersion liquid” means that water (for example, ultrapure water) is supplied from a nozzle to a coating film formed using the composition for forming an upper layer film of the present invention for a predetermined time (for example, 60 Second) after discharge, the rate of change in film thickness is within 3% of the initial film thickness when spin-dried at a predetermined rotation speed (for example, 4,000 rpm) for a predetermined time (for example, 15 seconds). It shall be.

[solvent]
Further, the composition for forming an upper layer film of the present invention contains a solvent for the purpose of dissolving the polymer component and the like. As the solvent, a solvent that hardly causes deterioration of lithography performance such as excessive intermixing with the photoresist film when applied on the resist film can be suitably used.

  Examples of the solvent include monohydric alcohols, polyhydric alcohols, polyhydric alcohol alkyl ethers, polyhydric alcohol alkyl ether acetates, ethers, cyclic ethers, higher hydrocarbons, ketones, Examples include esters and water.

  Specifically, the monohydric alcohol preferably has 4 to 10 carbon atoms, and examples thereof include butyl alcohol and pentanol. Examples of the polyhydric alcohol include ethylene glycol and propylene glycol. Examples of the alkyl ethers of polyhydric alcohols include ethylene glycol monomethyl ether and ethylene glycol monoethyl ether. Examples of polyhydric alcohol alkyl ether acetates include ethylene glycol ethyl ether acetate and diethylene glycol ethyl ether acetate. Ethers having an alkyl chain of 4 to 10 carbon atoms are preferred, for example, , Dipropyl ether, butyl methyl ether, diisoamyl ether, and the like. Examples of cyclic ethers include tetrahydrofuran and dioxane. Examples of higher hydrocarbons include decane, dodecene, and untecan. Examples of ketones include acetone and methyl ethyl ketone. Examples of esters include ethyl acetate, Examples include butyl acetate.

  Among these solvents, monohydric alcohols, ethers, cyclic ethers, alkyl ethers of polyhydric alcohols, alkyl ether acetates of polyhydric alcohols, and higher hydrocarbons are preferable. Those having at least one of the above monohydric alcohols and alkyl ethers having an alkyl chain having 4 to 10 carbon atoms are preferred.

  In addition, an additive such as a surfactant can be further blended in the composition for forming an upper layer film of the present invention for the purpose of improving coating properties, antifoaming properties, leveling properties and the like.

Examples of the surfactants include BM-1000 and BM-1100 (all manufactured by BM Chemie), MegaFuck F142D, F172, F173, and F183 (all Dainippon Ink and Chemicals, Inc.). ), FLORARD FC-135, FC-170C, FC-430, FC-431 (above, manufactured by Sumitomo 3M), Surflon S-112, S-113, S-131, S- 141, S-145 (above, manufactured by Asahi Glass), SH-28PA, -190, -193, SZ-6032, SF-8428 (above, manufactured by Toray Dow Corning Silicone), Emulgen A-60, 104P , 306P (manufactured by Kao Corporation) and other commercially available fluorine-based surfactants can be used. These may be used individually by 1 type and may be used in combination of 2 or more type.
It is preferable that the compounding quantity of this surfactant is 5 mass parts or less with respect to 100 mass parts of total amounts of a polymer (A) and a polymer (B).

[Photoresist pattern forming method]
Next, an embodiment of the photoresist pattern forming method of the present invention will be described. The method for forming a photoresist pattern of the present invention comprises a step of applying a photoresist composition on a substrate to form a photoresist film (step (1)), and the above-described upper layer film-forming composition is applied to the photoresist film. A step of applying and forming an upper layer film (step (2)), an immersion medium is disposed between the upper layer film and the lens, and the photo is passed through the immersion medium and a mask having a predetermined pattern. Irradiating the resist film and the upper layer film with exposure light and then developing the resist pattern to obtain a resist pattern (step (3)).
By providing such a process, the photoresist pattern forming method of the present invention has sufficient transmission with respect to the exposure wavelength, particularly 248 nm (KrF) and 193 nm (ArF), and causes almost intermixing with the photoresist film. It is formed on the photoresist film without immersion and maintains a stable coating that is extremely difficult to elute in a medium such as water during immersion exposure, and can form a high-resolution resist pattern while having a sufficiently high receding contact angle. The upper layer film, that is, the occurrence of watermark defects and pattern defect defects can be effectively suppressed at a normal scan speed (for example, 500 mm / s), and even if the scan speed is high (for example, 700 mm / s) The occurrence of defects can be effectively suppressed.

(Process (1))
Step (1) is a step of forming a photoresist film by applying a photoresist composition on a substrate. As the substrate, a silicon wafer, a silicon wafer coated with aluminum, or the like is usually used. In order to maximize the characteristics of the photoresist film, an organic or inorganic antireflection film is preferably formed on the surface of the substrate in advance (for example, Japanese Patent Publication No. 6-12252). (See the official gazette).
The type of the material for forming the photoresist film is not particularly limited, and it is appropriately selected from materials conventionally used for forming a photoresist film according to the purpose of use of the resist. do it. However, it is preferable to use a chemically amplified resist material containing an acid generator, particularly a positive resist material. Examples of the chemically amplified positive resist material include a radiation sensitive resin composition containing an acid dissociable group-modified alkali-soluble resin and a radiation sensitive acid generator as essential components. In such a resin composition, an acid is generated from an acid generator by irradiation (exposure), and an acid-dissociable group that protected an acidic group (for example, a carboxyl group) of the resin by the action of the generated acid. Dissociates to expose acidic groups. When the acidic group is exposed, the alkali solubility of the exposed portion of the resist is increased, and the exposed portion is dissolved and removed by the alkali developer, so that a positive resist pattern can be formed.
For the photoresist film, a solvent is added to the resin component for forming the photoresist film to obtain a solution in which the total solid content concentration is adjusted to 0.2 to 20% by mass, and the resulting solution is obtained with a pore diameter of about 30 nm. A coating liquid is prepared by filtering with a filter, and the coating liquid can be formed by coating on a substrate using a conventionally known coating method such as spin coating, cast coating, roll coating, or the like. it can. This photoresist film may be pre-baked (hereinafter may be referred to as “PB”) in order to volatilize the solvent. In forming the photoresist film, the coating solution may be prepared by itself or a commercially available resist solution may be used as the coating solution.

(Process (2))
Step (2) is a step of forming the upper film by applying the above-described upper film forming composition to the photoresist film. This step is a step of forming the upper layer film by applying the above-described upper layer film forming composition on the surface of the photoresist film formed in the step (1) and preferably baking again. By forming the upper layer film, the immersion liquid is prevented from coming into direct contact with the photoresist film during the immersion exposure, and the lithography performance of the photoresist film is reduced by the penetration of the immersion liquid, or the photoresist film It is possible to effectively prevent the lens of the projection exposure apparatus from being contaminated by the components eluted from
The thickness of the upper layer film is preferably as close as possible to an odd multiple of λ / 4m (where λ is the wavelength of radiation and m is the refractive index of the protective film). This is because the reflection suppressing effect at the upper interface of the photoresist film is increased.

(Process (3))
In the step (3), an immersion medium is disposed between the upper layer film and the lens, and the photoresist film and the upper layer film are irradiated with exposure light through the immersion medium and a mask having a predetermined pattern. And then developing the resist pattern.
As the immersion medium, a liquid having a higher refractive index than air is usually used. Specifically, water is preferably used, and pure water is more preferably used. In addition, you may adjust pH of immersion liquid as needed. With this immersion medium interposed (that is, with the immersion medium filled between the lens of the exposure apparatus and the photoresist film), the photoresist film is irradiated with radiation through a mask having a predetermined pattern. To expose.
The radiation that can be used in the immersion exposure may be appropriately selected according to the type of the photoresist film and the upper layer film used, and examples thereof include visible light; ultraviolet light such as g-line and i-line; excimer laser. Various radiations such as deep ultraviolet rays such as X-rays, X-rays such as synchrotron radiation, and charged particle beams such as electron beams can be used. Among these, it is preferable to use an ArF excimer laser (wavelength 193 nm) or a KrF excimer laser (wavelength 248 nm). Moreover, what is necessary is just to set suitably exposure conditions, such as a radiation dose, according to the compounding composition of a radiation sensitive resin composition, the kind of additive, etc.
In order to improve the resolution, pattern shape, developability, and the like of the photoresist film, baking (PEB) is preferably performed after exposure. The firing temperature is appropriately adjusted depending on the type of the radiation-sensitive resin composition used, and is usually 30 to 200 ° C, preferably 50 to 150 ° C.
A desired photoresist pattern can be formed by performing development after exposure or PEB and washing as necessary. The upper layer film is formed by the upper layer film forming composition which is one embodiment of the present invention. Therefore, this upper layer film does not need to be removed by a separate peeling step, and can be easily removed during development or washing after development. In developing, an alkaline developer is usually used.
Examples of the developer include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, dimethylethanol. Amine, triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, 1,5-diazabicyclo- [4. 3.0] It is preferable to use an alkaline aqueous solution in which at least one alkaline compound such as 5-nonane is dissolved. Especially, the aqueous solution of tetraalkylammonium hydroxide can be used suitably.
For example, an appropriate amount of a water-soluble organic solvent including alcohols such as methanol and ethanol, and a surfactant can be added to the developer. In addition, when developing using said alkaline aqueous solution, it wash | cleans with water after image development normally. In addition, if it dries suitably after image development or the water washing as needed, the target photoresist pattern can be formed.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. In the examples and comparative examples, “parts” and “%” are based on mass unless otherwise specified. Moreover, the measuring method of various physical-property values and the evaluation method of various characteristics are shown below.

[Evaluation of polymer]
(1) Measuring method of molecular weight (Mw, Mn) Mw and Mn of the polymers (A1) to (A3) are the GPC column (product of Tosoh Corp.) Name, “G2000H _XL ”; 2; “G3000H _XL ”; 1; “G4000H _XL ”; 1), monodisperse under analytical conditions of flow rate 1.0 ml / min, elution solvent tetrahydrofuran, column temperature 40 ° C. It was measured by gel permeation chromatography (GPC) using polystyrene as a standard.

[Synthesis Example 1] Synthesis of monomer (a-1a)

  75 g of 1,6-hexanediol and 30 g of p-toluenesulfonyl chloride were placed in a 1 liter reaction flask, and 300 ml of THF was added thereto. After slowly dropping 24 g of triethylamine, the mixture was stirred at room temperature for 20 hours. After completion of the reaction, THF was distilled off using an evaporator, the residue was extracted with 500 ml of ethyl acetate, washed with 200 ml of water, and then the organic layer was washed with 200 ml of saturated brine, and then dried over anhydrous magnesium sulfate. I let you. The organic layer was concentrated, purified by silica gel column chromatography (developing solvent: hexane / ethyl acetate = 2/3), and 32.8 g of the compound represented by the above formula (a-1a-1) (yield: 76). %).

  Under a nitrogen atmosphere, 7.2 g of sodium hydride containing 40% oil was placed in a 1 liter reaction flask, and 250 ml of anhydrous DMF was added thereto. The DMF solution was cooled to 0 ° C., 45 g of di-t-butyl malonate was slowly added dropwise, and the mixture was stirred at 40 ° C. for 3 hours. Thereafter, 32.5 g of the compound represented by the above formula (a-1a-1) was slowly added dropwise at room temperature, followed by stirring at 30 ° C. for 15 hours. After completion of the reaction, 400 ml of ethyl acetate and 300 ml of water were added to the reaction solution and washed with water. Subsequently, the organic layer was washed with 300 ml of saturated brine, and then dried over anhydrous magnesium sulfate. The organic layer was concentrated and purified by silica gel column chromatography (developing solvent: hexane / ethyl acetate = 8/1 and 2/1) to obtain 33.3 g of the compound represented by the above formula (a-1a-2) ( Yield: 84%) was obtained.

Under a nitrogen atmosphere, 31.6 g of the compound represented by the above formula (a-1a-2) and 15.2 g of triethylamine were placed in a 1 liter reaction flask, and 300 ml of toluene was added thereto. The toluene solution was cooled to 0 ° C., and 11 g of methacrylic acid chloride was slowly added dropwise, followed by stirring at room temperature for 5 hours. After completion of the reaction, 400 ml of ethyl acetate and 300 ml of water were added to the reaction solution and washed with water. Subsequently, the organic layer was washed with 300 ml of saturated brine, and then dried over anhydrous magnesium sulfate. The organic layer was concentrated, purified by silica gel column chromatography (developing solvent: hexane / ethyl acetate = 8/1), and 31.7 g of the compound represented by the above formula (a-1a-3) (yield: 83). %).

  12.0 g of the compound represented by the above formula (a-1a-3) was placed in a 300 ml eggplant flask, 50 ml of trifluoroacetic acid was added thereto, and the mixture was stirred at room temperature for 10 hours. After completion of the reaction, 50 ml of toluene was added to the reaction solution, and toluene and trifluoroacetic acid were distilled off using an evaporator. The procedure of adding 50 ml of toluene again to the residue and evaporating it was repeated three times to completely remove trifluoroacetic acid. Thereafter, the precipitated white solid was washed with hexane and suction filtered to obtain 7.8 g (yield: 92%) of the compound (a-1a) represented by the above formula (a-1a).

[Synthesis Example 2] Synthesis of monomer (a-1b)

窒素雰囲気下、クエン酸トリエチル ５．０ｇ、 トリエチルアミン ３．７ｇ、１，４−ジアザビシクロ〔２，２，２〕オクタン ０．６ｇを２００ｍｌの反応フラスコに入れ、そこにトルエン １００ｍｌを加えた。０℃にトルエン溶液を冷やし、メタクリル酸クロライド ２．８ｇをゆっくりと滴下した後、室温で４時間攪拌した。反応終了後、反応溶液に酢酸エチル２００ｍｌ及び水１００ｍｌを加え水洗し、続いて有機層を１００ｍｌの飽和食塩水で洗浄した後、無水硫酸マグネシウムで乾燥させた。有機層を濃縮し、シリカゲルカラムクロマトグラフィー（展開溶媒：ヘキサン／酢酸エチル＝８／１）で精製を行い、上記式（ａ−１ｂ−１）で表される化合物４．６ｇ（収率：７４％）を得た。

Under a nitrogen atmosphere, 5.0 g of triethyl citrate, 3.7 g of triethylamine, and 0.6 g of 1,4-diazabicyclo [2,2,2] octane were placed in a 200 ml reaction flask, and 100 ml of toluene was added thereto. The toluene solution was cooled to 0 ° C. and 2.8 g of methacrylic acid chloride was slowly added dropwise, followed by stirring at room temperature for 4 hours. After completion of the reaction, 200 ml of ethyl acetate and 100 ml of water were added to the reaction solution and washed with water. Subsequently, the organic layer was washed with 100 ml of saturated saline and then dried over anhydrous magnesium sulfate. The organic layer was concentrated and purified by silica gel column chromatography (developing solvent: hexane / ethyl acetate = 8/1) to obtain 4.6 g of the compound represented by the above formula (a-1b-1) (yield: 74 %).

4.0 g of the compound represented by the above formula (a-1b-1) was placed in a 200 ml eggplant flask, and 30 ml of a mixed solvent of methanol / water = 5/1 was added thereto. The mixed solvent was cooled to 0 ° C., 3 g of 10% aqueous lithium hydroxide was added thereto, and then stirred for 1 hour while maintaining 0 ° C. After completion of the reaction, the solvent was distilled off using an evaporator. Thereafter, 100 ml of toluene was added to the residue, and a series of operations for removing the solvent again was repeated three times to remove water. The residue is dissolved in a mixed solvent of ethyl acetate / methanol = 8/1, purified by silica gel column chromatography (developing solvent: ethyl acetate / methanol = 8/1), and the compound represented by the above formula (a-1b) 1.4 g (yield: 47%) of (a-1b) was obtained.

[Synthesis Example 3] Synthesis of Polymer (A1) 1.82 g (4 mol%) of the above-mentioned compound (a-1a) used for obtaining the above-mentioned repeating unit (a) and the above-mentioned repeating unit (f). 35.62 g (81 mol%) of the monomeric methacrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-butyl) ester used to obtain the initiator [2 , 2′-azobis- (methyl 2-methylpropionate)] was prepared as a monomer solution in which 40.00 g of isopropanol was dissolved.
On the other hand, 50 g of isopropanol was put into a 200 ml three-necked flask equipped with a thermometer and a dropping funnel and purged with nitrogen for 30 minutes. After purging with nitrogen, the inside of the flask was heated to 80 ° C. while stirring with a magnetic stirrer.
And the monomer solution prepared beforehand was dripped over 2 hours using the dropping funnel. After completion of the dropwise addition, the reaction was further continued for 1 hour, and 10 g of an isopropanol solution of 2.55 g (15 mol%) of the monomer [vinyl sulfonic acid] used for obtaining the above repeating unit (s) was dropped over 30 minutes. did. Thereafter, the reaction was further performed for 1 hour, and then cooled to 30 ° C. or lower to obtain a copolymer solution.

  The obtained copolymer solution was concentrated to 150 g and then transferred to a separatory funnel. The separatory funnel was charged with 50 g of methanol and 600 g of n-hexane to carry out separation and purification. After separation, the lower layer solution was recovered. This lower layer solution was diluted with isopropanol to 100 g, and again transferred to a separatory funnel. Thereafter, 50 g of methanol and 600 g of n-hexane were added to the separatory funnel, separation and purification were performed, and the lower layer liquid was recovered after separation. The recovered lower layer solution was replaced with 4-methyl-2-pentanol, and the total amount was adjusted to 250 g. After the adjustment, 250 g of water was added for separation and purification. After separation, the upper layer liquid was recovered. The recovered upper layer liquid was replaced with 4-methyl-2-pentanol to obtain a resin solution. The solid content concentration of the sample after solvent replacement was calculated from the mass of the residue after 1 hour of heating on a hot plate heated to 140 ° C. by placing 0.3 g of the resin solution on an aluminum dish, and then forming a protective film The composition solution was used for the preparation and yield calculation. Mw of the copolymer contained in the obtained resin solution was 10010, Mw / Mn was 1.55, and the yield was 75%. Further, it is derived from the above-mentioned compound (a-1a), methacrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-butyl) ester contained in this copolymer. The content of the repeating unit and the repeating unit derived from vinyl sulfonic acid was 5: 93: 2 (mol%). Let this copolymer be a specific polymer (A1-1).

The composition which showed specific polymer (A1-2)-(A1-6) and polymer (A'1-2)-(A'1-3) in Table 1 using the method similar to the synthesis example 3. Was synthesized. Table 2 shows the composition of the obtained polymer.

Synthesis Example 4 Synthesis of Polymer (A2-1) A mixed solution in which 13.85 g of 2,2-azobis (methyl 2-methylisopropionate) was dissolved in 13.85 g of methyl ethyl ketone was prepared.
Meanwhile, in a 2000 ml three-necked flask equipped with a thermometer and a dropping funnel, 198.87 g of methacrylic acid (1,1,1,3,3,3-hexafluoro-2-propyl) ester, methacrylic acid (1, 1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester (101.13 g) and methyl ethyl ketone (586.15 g) were added and purged with nitrogen for 30 minutes. After purging with nitrogen, the flask was heated to 75 ° C. while stirring with a magnetic stirrer.
And the prepared mixture solution was dripped over 5 minutes using the dropping funnel, and it was made to age | cure | ripen for 360 minutes. Then, it cooled to 30 degrees C or less, and obtained the copolymer liquid.

Next, the obtained copolymer solution was concentrated to 600 g and then transferred to a separatory funnel. To this separatory funnel, 193 g of methanol and 1542 g of n-hexane were added for separation and purification. After separation, the lower layer solution was recovered. 117 g of methyl ethyl ketone and 1870 g of n-hexane were added to the recovered lower layer solution, and separation and purification were performed. After separation, the lower layer solution was recovered. Further, 93 g of methanol, 77 g of methyl ethyl ketone, and 1238 g of n-hexane were added to the recovered lower layer solution, followed by separation and purification. After separation, the lower layer solution was recovered. The recovered lower layer solution was substituted with 4-methyl-2-pentanol, and this solution was washed with distilled water and again substituted with 4-methyl-2-pentanol to obtain a polymer solution. The solid content concentration of the sample (polymer solution) after substitution with 4-methyl-2-pentanol was determined by weighing 0.3 g of the polymer solution into an aluminum dish and 140 ° C. × 1 on a hot plate. After heating for a period of time, the mass was calculated from the mass of the polymer solution before heating and the mass of the residue (after heating). This solid content concentration was used for the preparation of the upper layer film-forming composition solution and the yield calculation.
Mw of the copolymer contained in the obtained polymer solution was 10200, Mw / Mn was 1.65, and the yield was 65%. Further, repeating units derived from methacrylic acid (1,1,1,3,3,3-hexafluoro-2-propyl) ester contained in this copolymer, and methacrylic acid (1,1,1-trimethyl) The content of repeating units derived from (fluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester was 69.5: 30.5 (mol%). This copolymer is referred to as “polymer (A2-1)”.
The receding contact angle with water at the time of film formation using the polymer (A2-1) was 82 °.

Synthesis Example 5 Synthesis of Polymer (A3-1) 46.95 g (85 mol%) of methacrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester A monomer solution was prepared by dissolving 6.91 g of initiator (methyl 2,2′-azobis- (methyl 2-methylpropionate)) in 100 g of isopropanol.
Meanwhile, 50 g of isopropanol was charged into a 500 ml three-necked flask equipped with a thermometer and a dropping funnel, and purged with nitrogen for 30 minutes. After purging with nitrogen, the inside of the flask was heated to 80 ° C. while stirring with a magnetic stirrer.
And the monomer solution prepared beforehand was dripped over 2 hours using the dropping funnel. After completion of dropping, the reaction was further continued for 1 hour, and 10 g of an isopropanol solution of 3.05 g (15 mol%) of vinyl sulfonic acid was dropped over 30 minutes. Thereafter, the reaction was further performed for 1 hour, and then cooled to 30 ° C. or lower to obtain a copolymer solution.

Subsequently, after concentrating the obtained copolymer liquid to 150 g, it moved to the separatory funnel. The separatory funnel was charged with 50 g of methanol and 600 g of n-hexane to carry out separation and purification. After separation, the lower layer solution was recovered. This lower layer solution was diluted with isopropanol to 100 g, and again transferred to a separatory funnel. Thereafter, 50 g of methanol and 600 g of n-hexane were added to the separatory funnel, separation and purification were performed, and the lower layer liquid was recovered after separation. The recovered lower layer solution was replaced with 4-methyl-2-pentanol, and the total amount was adjusted to 250 g. After the adjustment, 250 g of water was added for separation and purification. After separation, the upper layer liquid was recovered. Next, the recovered upper layer liquid was substituted with 4-methyl-2-pentanol to obtain a polymer solution. The solid content concentration of the sample (polymer solution) after substitution with 4-methyl-2-pentanol was measured by weighing 0.5 g of the polymer solution in an aluminum dish and heating it to 155 ° C. on a hot plate. After heating for 30 minutes on the hot plate, the mass was calculated from the mass of the polymer solution before heating and the mass of the residue (after heating). This solid content concentration was used for the preparation of the upper layer film-forming composition solution and the yield calculation.
Mw of the copolymer contained in the obtained polymer solution was 9760, Mw / Mn was 1.51, and the yield was 65%. Moreover, the repeating unit derived from methacrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester contained in this copolymer, and derived from vinyl sulfonic acid The content of the repeating unit was 98: 2 (mol%). This copolymer is referred to as “polymer (A3-1)”.
In addition, the receding contact angle with water when the film was formed using the polymer (A3-1) was 69 °.

Using the same method as in Synthesis Example 5, the specific polymer (A3-2) was synthesized with the composition shown in Table 1. Table 2 shows the composition of the obtained polymer.

In the table, each monomer is as follows.
s-2: vinylsulfonic acid ca: 2-((3- (methacryloyloxy) propoxy) carbonyl) cyclohexanecarboxylic acid f-1a: methacrylic acid (1,1,1-trifluoro-2-trifluoromethyl- 2-hydroxy-4-butyl) ester f-1b: methacrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester f-2: methacrylic acid (1-tri Fluoromethyl-2,2,2-trifluoroethyl) ester

[Examples 1 to 18]
A composition for forming an upper layer film for immersion was prepared using the resin obtained in the above example. The solvent was added so that the total amount of the solid content of the resin shown in Table 1 was 4 g and the solvent (G) shown in Table 1 was 96 g in the weight ratio indicated, and the mixture was stirred for 2 hours, and then filtered through a filter having a pore size of 200 nm. Prepared. In Table 1, 4-methyl-2-pentanol (hereinafter “G-1”) represents diisoamyl ether (hereinafter “G-2”). In Table 1, the solvent ratio in the case of a mixed solvent represents a weight ratio. The obtained composition for forming an upper layer film was evaluated by the following method. The results are shown in Table 3.

[Comparative Examples 1 to 9]
Except using the components shown in Table 1, compositions for forming upper layer films of Comparative Examples 1 to 9 were obtained in the same manner as in Example 1.

[Preparation Example] Preparation of Photoresist Composition A photoresist composition for forming a photoresist film was prepared by the following method.

[Synthesis Example 4] Synthesis Example of Photoresist Composition Polymer (M) The following compound (M-1) 53.93 g (50 mol%), compound (M-2) 35.38 g (40 mol%), compound (M-5) A monomer solution in which 10.69 g (10 mol%) was dissolved in 200 g of 2-butanone and 5.58 g of dimethyl 2,2′-azobis (2-methylpropionate) was further added was prepared. Then, a 500 ml three-necked flask charged with 100 g of 2-butanone was purged with nitrogen for 30 minutes. After purging with nitrogen, the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added dropwise using a dropping funnel over 3 hours. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization, the polymerization solution was cooled with water to 30 ° C. or lower, poured into 2000 g of methanol, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 400 g of methanol on the slurry, filtered, and dried at 50 ° C. for 17 hours to obtain a white powder polymer (74 g, yield 74%). . This polymer has Mw of 6900, Mw / Mn = 1.70, and as a result of ¹³ C-NMR analysis, each repeating unit derived from compound (M-1), compound (M-2), and compound (M-3). Was a copolymer having a content of 53.0: 37.2: 9.8 (mol%). This polymer is referred to as “acrylic polymer (c)”. In addition, content of the low molecular weight component derived from each monomer in this polymer was 0.03 mass% with respect to 100 mass% of this polymer. This is designated as polymer (M).

  The photoresist composition (α) for forming the photoresist film is composed of 100 parts by mass of the polymer for photoresist composition (M) and triphenylsulfonium nonafluoro-n-butanesulfonate as an acid generator (C). 5 parts by mass, 6 parts by mass of 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium / nonafluoro-n-butanesulfonate, R-(+)-(tert- (Butoxycarbonyl) -2-piperidinemethanol (0.65 parts by mass) was mixed, and as a solvent (E), 2900 parts by mass of propylene glycol monomethyl ether acetate, 120 parts by mass of cyclohexanone, and 100 parts by mass of γ-butyrolactone were added. It was prepared by filtering through a filter.

[Evaluation]
Various evaluation shown below was performed about the composition for upper-layer film formation of Examples 1-18 and Comparative Examples 1-9. The evaluation results are shown in Table 3.

(1) Peeling resistance test An 8-inch silicon wafer not subjected to HMDS treatment was used as a substrate.
A composition for forming an upper layer film was spin-coated on the substrate with CLEAN TRACK ACT8, and then subjected to PB under the conditions of 90 ° C. × 60 seconds to obtain an upper layer film having a thickness of 30 nm. Thereafter, rinsing with pure water was performed for 60 seconds in CLEAN TRACK ACT8, and drying by shaking was performed.
The case where peeling was observed at the edge portion after rinsing by visual observation was evaluated as “×”, and the case where peeling was not observed was evaluated as “◯”. The results are shown in Table 3.

(2) Defect performance (watermark defect)
As the substrate, a 12-inch silicon wafer having a 77 nm-thick lower layer antireflection film (“ARC29A”, manufactured by Brewer Science) on the surface was used. Note that “CLEAN TRACK ACT12” (manufactured by Tokyo Electron Ltd.) was used for the formation of the lower antireflection film.

  A radiation sensitive resin composition (α) was spin-coated on the substrate by the CLEAN TRACK ACT12, and then a PB (90 ° C., 60 seconds) film thickness of 120 nm was obtained. Then, after spin-coating the upper film | membrane formation composition solution on the photoresist film, the coating film (upper film | membrane) with a film thickness of 30 nm was obtained by PB (90 degreeC, 60 second). Next, exposure is performed through a mask pattern using an ArF projection exposure apparatus (model number “S610C”, manufactured by Nikon Corporation) under the conditions of NA = 0.85, σ0 / σ1 = 0.97 / 0.78, and Azimuth. It was. At this time, pure water was placed as an immersion solvent between the upper surface of the resist (photoresist film) and the immersion exposure machine lens. Then, after baking at PB (115 ° C., 60 seconds), development was performed at 23 ° C. for 60 seconds with a 2.38 mass% tetramethylammonium hydroxide aqueous solution, washed with water, and dried to form a positive resist pattern. Formed. At this time, an exposure amount for forming a line-and-space pattern (1L1S) having a line width of 100 nm with a one-to-one line width was defined as an optimum exposure amount, and this optimum exposure amount was defined as sensitivity. For this measurement, a scanning electron microscope (“S-9380”, manufactured by Hitachi High-Technologies Corporation) was used.

  Thereafter, the defect performance on the line and space pattern (1L1S) having a line width of 100 nm was measured using “KLA2810” manufactured by KLA-Tencor. Specifically, the defect measured by “KLA2810” is observed using a scanning electron microscope (“S-9380”, manufactured by Hitachi High-Technologies Corporation), and is expected to be derived from ArF excimer laser immersion exposure. A watermark defect (water-mark defect) and a bubble defect were distinguished. And the number of those was measured and it was set as the defect performance. The results are shown in Table 3. The evaluation of the watermark defect is “◯” when the number of detected watermark defects is less than 50, “Δ” when the number is 50 or more and less than 100, and “X” when the number exceeds 100. The evaluation results are shown in Table 3. In Table 3, “watermark defect” indicates this evaluation. The evaluation of bubble defects was “◯” when the number of detected bubble defects was 50 or less, “Δ” when the number was 50 or more and less than 100, and “X” when the number exceeded 100. The evaluation results are shown in Table 3.

(3) Defect performance (bridge defect)
A radiation sensitive resin composition (α) was spin-coated on the substrate by the CLEAN TRACK ACT12, and then a PB (90 ° C., 60 seconds) film thickness of 120 nm was obtained. Then, after spin-coating the upper film | membrane formation composition solution on the photoresist film, the coating film (upper film | membrane) with a film thickness of 30 nm was obtained by PB (90 degreeC, 60 second). Next, exposure is performed through a mask pattern under conditions of NA = 0.85, σ ₀ / σ ₁ = 0.97 / 0.78, and Azimuth with an ArF excimer laser immersion exposure apparatus (model number “S610C”). went. At this time, pure water was placed as an immersion solvent between the upper surface of the resist (photoresist film) and the immersion exposure machine lens. Then, after baking at PB (115 ° C., 60 seconds), development was performed at 23 ° C. for 60 seconds with a 2.38 mass% tetramethylammonium hydroxide aqueous solution, washed with water, and dried to form a positive resist pattern. Formed. At this time, an exposure amount for forming a line-and-space pattern (1L1S) having a line width of 100 nm with a one-to-one line width was defined as an optimum exposure amount, and this optimum exposure amount was defined as sensitivity. For this measurement, a scanning electron microscope (“S-9380”, manufactured by Hitachi High-Technologies Corporation) was used.

  Thereafter, the defect performance on the line and space pattern (1L1S) having a line width of 100 nm was measured using “KLA2810” manufactured by KLA-Tencor. Specifically, the defects measured by “KLA2810” were observed using a scanning electron microscope (“S-9380”, manufactured by Hitachi High-Technologies Corporation) to confirm bridge defects. And the number of those was measured and it was set as the defect performance. The results are shown in Table 6. The evaluation of the bridge defect is “◯” when the number of detected bridge defects is less than 50, “Δ” when the number is 50 or more and less than 100, and “X” when the number exceeds 100. The evaluation results are shown in Table 3. In Table 3, “bridge defect” indicates this evaluation.

As is clear from Table 3, it can be confirmed that the upper layer film-forming compositions of Examples 1 to 18 have better peeling resistance and fewer watermark defects than the compositions of Comparative Examples 1, 4, and 5. It was. Moreover, it has confirmed that peeling resistance was favorable compared with the composition of the comparative example 2. Moreover, it has confirmed that there were few bridge | bridging defects compared with the composition of Comparative Example 3,8,9. Furthermore, it was confirmed that watermark defects can be suppressed as compared with the compositions of Comparative Examples 6 and 7.
From the above, it has been found that the upper layer film of the present invention can form an upper layer film that suppresses watermark defects and bridge defects and has good peeling resistance.

  The composition for forming an upper layer film of the present invention can form an upper layer film that can be suitably used for immersion exposure, and is extremely preferably used in a semiconductor device manufacturing process that is expected to be further miniaturized in the future. be able to.

Claims (7)

  A composition for forming a liquid immersion upper layer film comprising a polymer component (A) having a repeating unit (a) containing a plurality of carboxyl groups and a solvent (B). The composition for forming a liquid immersion upper layer film according to claim 1, wherein the repeating unit containing a plurality of carboxyl groups is represented by the following formula (a1).

(In the above formula (a1), Q is an (m + 1) -valent organic group, R independently represents a hydrogen atom, a methyl group or a trifluoromethyl group, and m is an integer of 2 to 4. )   In the formula (a1), Q is an (m + 1) -valent aliphatic hydrocarbon group having 1 to 10 carbon atoms or an (m + 1) -valent alicyclic hydrocarbon group having 3 to 10 carbon atoms. 3. The composition for forming a liquid immersion upper layer film according to 1 or 2.   The composition for forming a liquid immersion upper layer film according to any one of claims 1 to 3, wherein the polymer component (A) has a repeating unit (s) having a sulfo group.   The composition for liquid immersion upper film formation in any one of Claims 1-4 in which a polymer component (A) has a repeating unit (f) which has a fluorine atom.   A liquid immersion upper film formed by using the composition for forming a liquid immersion upper film according to claim 1. A step (1) of applying a photoresist composition on a substrate to form a photoresist film;
Applying the composition for liquid immersion upper layer film formation according to any one of claims 1 to 6 on the photoresist film to form an upper layer film on the photoresist film;
An immersion medium is disposed on the upper layer film, and the upper layer film and the photo resist film are irradiated with exposure light having passed through a mask having a predetermined pattern and an immersion liquid, and thereby the upper layer film and the photo film. A step (3) of exposing the resist film;
And a step (4) of developing the exposed upper layer film and the photoresist film with a developer.