JPWO2013047072A1 - Composition for forming liquid immersion upper layer film and method for forming resist pattern - Google Patents

Abstract

This invention contains the structural unit (I) containing the polymer component containing [A] polymer (A1), and the [B] solvent, and polymer (A1) containing group represented by following formula (1). The composition for forming a liquid immersion upper layer film. In the following formula (1), R ¹ is an alkali dissociable group. R ² is an (n + 1) -valent linking group. A is —CO—O— *, —SO ₂ —O— *, an oxygen atom, or —NR ³ —. When A is an oxygen atom, the part directly connected to A in R ² is not a carbonyl group or a sulfonyl group.

Description

  The present invention relates to a composition for forming a liquid immersion upper layer film and a method for forming a resist pattern.

  With the miniaturization of various electronic device structures such as semiconductor devices and liquid crystal devices, pattern miniaturization in the lithography process is required. At present, it is possible to form a fine pattern with a line width of about 90 nm using, for example, an ArF excimer laser, but further fine pattern formation will be required in the future.

  In response to such demands, the use of an immersion exposure method in which exposure is performed by filling a space between a lens and a resist film with an immersion medium such as pure water or a fluorine-based inert liquid is expanding. This immersion exposure method has the advantage that the numerical aperture (NA) of the lens can be increased and high resolution can be obtained.

  However, the resist pattern forming method by the immersion exposure method has problems such as elution of the photoresist composition into the immersion medium and generation of pattern defects due to droplets remaining on the resist film surface. As a technique for improving such inconvenience and improving scanning speed, a method of providing a liquid immersion upper layer film on a resist film is known (Japanese Patent Application Laid-Open No. 2006-91798, International Publication No. 2008/47678 pamphlet). And International Publication No. 2009/41270 pamphlet). Such a liquid immersion upper layer film is required to have superior water repellency in order to satisfy the above requirements, but on the other hand, due to its excellent water repellency, a bridge defect in which a part of resist patterns are connected to each other. Further, development defects such as blob defects due to adhesion of development residues may be caused, and as a result, the accuracy of the pattern shape of the resist pattern may be reduced.

JP 2006-91798 A International Publication No. 2008/47678 Pamphlet International Publication No. 2009/41270 Pamphlet

  The present invention has been made on the basis of the circumstances as described above, and its purpose is to provide basic characteristics as a liquid immersion upper layer film such as water repellency and solubility in a developer, and bridge defects in resist pattern formation. An object of the present invention is to provide a composition for forming a liquid immersion upper layer film that can suppress development defects such as blob defects and can form a resist pattern having an excellent pattern shape.

（式（１）中、Ｒ^１は、アルカリ解離性基である。Ｒ^２は、（ｎ＋１）価の連結基である。Ａは、−ＣＯ−Ｏ−＊、−ＳＯ_２−Ｏ−＊、酸素原子又は−ＮＲ^３−である。Ｒ^３は、水素原子又はアルカリ解離性基である。＊は、Ｒ^１に結合する部位を示す。但し、Ａが酸素原子であるとき、Ｒ^２のＡに直結する部位が、カルボニル基又はスルホニル基となる場合はない。ｎは、１〜３の整数である。但し、ｎが２以上の場合、複数のＲ^１及びＡは、それぞれ同一でも異なっていてもよい。）The invention made to solve the above problems is
[A] a polymer component containing the polymer (A1) (hereinafter also referred to as “[A] polymer component”), and [B] a solvent,
The polymer (A1) is a composition for forming a liquid immersion upper layer film having a structural unit (I) containing a group represented by the following formula (1).

(In Formula (1), R ¹ is an alkali dissociable group. R ² is an (n + 1) -valent linking group. A is —CO—O— *, —SO ₂ —O— *, An oxygen atom or —NR ³ —, R ³ is a hydrogen atom or an alkali-dissociable group, * represents a site bonded to R ¹ , provided that when A is an oxygen atom, A in R ² There is no case where the site directly connected to carbonyl group or sulfonyl group, n is an integer of 1 to 3. However, when n is 2 or more, a plurality of R ¹ and A are the same or different. May be.)

  The composition for forming a liquid immersion upper layer film of the present invention contains a polymer (A1). When the polymer (A1) contains a group having an alkali-dissociable group represented by the above formula (1), the liquid immersion upper film formed from the liquid immersion upper film forming composition has water repellency. Excellent and good solubility in an alkali developer. In addition, after alkali development, the alkali-dissociable group is dissociated, so that the fluorine atom content in the liquid immersion upper layer film is lowered, and it is assumed that the affinity for the alkali developer is improved. As a result, development defects such as bridge defects and blob defects in resist pattern formation can be suppressed, and a resist pattern having an excellent pattern shape can be formed.

（式（２）中、Ｒ^５は、水素原子、メチル基、ヒドロキシメチル基又はトリフルオロメチル基である。Ｒ^４は、−ＣＯ−Ｏ−、−Ｏ−ＣＯ−Ｏ−、−Ｏ−、−ＳＯ_２−、−ＣＯ−ＮＨ−又は−ＳＯ_２ＮＨ−である。ｎ、Ｒ^１及びＲ^２は、上記式（１）と同義である。）The structural unit (I) is preferably represented by the following formula (2).

(In Formula (2), R ⁵ is a hydrogen atom, a methyl group, a hydroxymethyl group, or a trifluoromethyl group. R ⁴ is —CO—O—, —O—CO—O—, —O—, -SO ₂ -, - CO-NH- or _-SO 2 NH- .n, ^{R 1} and ^{R 2} is as defined in the above formula (1)).

  When the structural unit (I) has the specific structure, the liquid immersion upper film formed from the liquid immersion upper film forming composition is superior in water repellency and has better solubility in an alkali developer. Become. In addition, development defects such as bridge defects and blob defects in resist pattern formation can be more effectively suppressed, and a resist pattern that is more excellent in pattern shape can be formed.

（式（３）中、Ｒ^６〜Ｒ^９は、水素原子、フッ素原子又はパーフルオロアルキル基である。但し、Ｒ^６〜Ｒ^９の少なくとも１つは、フッ素原子又はパーフルオロアルキル基である。Ｒ^１０は、水素原子、フッ素原子又は１価の有機基である。
式（４）中、ａは、０又は１である。ｂは、０〜５の整数である。Ｒ^１１は、フッ素原子、又はフッ素原子を含んでいてもよい１価の有機基である。但し、ｂが２以上の場合、複数のＲ^１１は、同一でも異なっていてもよい。）The alkali dissociable group for R ¹ is preferably a monovalent hydrocarbon group having 1 to 20 carbon atoms, a group represented by the following formula (3), or a group represented by the following formula (4).

(In the formula (3), R ^{6 to} R ⁹ are a hydrogen atom, a fluorine atom or a perfluoroalkyl group, provided that at least one of R ^{6 to} R ⁹ is a fluorine atom or a perfluoroalkyl group. R ¹⁰ is a hydrogen atom, a fluorine atom or a monovalent organic group.
In the formula (4), a is 0 or 1. b is an integer of 0-5. R ¹¹ is a fluorine atom or a monovalent organic group that may contain a fluorine atom. However, when b is 2 or more, the plurality of R ¹¹ may be the same or different. )

When the alkali dissociable group of R ¹ has the above specific structure, the liquid immersion upper film formed from the liquid immersion upper film forming composition is excellent in water repellency and has sufficient basic characteristics as a liquid immersion upper film. Can be satisfied. Moreover, it becomes possible by using the said composition for liquid immersion upper layer film formation to form the resist pattern which is excellent in pattern shape.

  [A] The content ratio of the structural unit (I) in the polymer component is preferably 0.1 mol% or more and 50 mol% or less with respect to all the structural units constituting the [A] polymer component. By setting the content ratio of the structural unit (I) to 0.1 mol% or more, the liquid immersion upper layer film formed from the liquid immersion upper layer film-forming composition has further excellent water repellency, and 50 mol % Or less, the [A] polymer component is excellent in solubility in an alkali developer and also excellent in peeling resistance.

  [A] The polymer component contains at least one group selected from the group consisting of a fluorinated alkyl group and a fluorinated hydroxyalkyl group in the same or different polymer as the polymer (A1), and the above formula It is preferable to further have the structural unit (II) not containing the group represented by (1). [A] When the polymer component further has a structural unit (II) containing a fluorine atom, the liquid immersion upper film formed from the liquid immersion upper film forming composition has further excellent water repellency. The basic characteristics as a liquid immersion upper film can be sufficiently satisfied.

（式（１１）中、Ｒ^２３は、水素原子、ハロゲン原子、ニトロ基、アルキル基、１価の脂環式炭化水素基、アルコキシ基、アシル基、アラルキル基又はアリール基である。上記アルキル基、脂環式炭化水素基、アルコキシ基、アシル基、アラルキル基及びアリール基が有する水素原子の一部又は全部は置換されていてもよい。Ｒ^２４は、−Ｃ（＝Ｏ）−Ｒ^２５、−Ｓ（＝Ｏ）_２−Ｒ^２６、−Ｒ^２７−ＣＮ又は−Ｒ^２８−ＮＯ_２である。Ｒ^２５及びＲ^２６は、それぞれ独立して、水素原子、アルキル基、フッ素化アルキル基、１価の脂環式炭化水素基、アルコキシ基、シアノ基、シアノメチル基、アラルキル基又はアリール基である。但し、Ｒ^２５又はＲ^２６とＲ^２３とが互いに結合して環構造を形成していてもよい。Ｒ^２７及びＲ^２８は、それぞれ独立して、単結合、メチレン基又は炭素数２〜５のアルキレン基である。）[A] The polymer component is at least one group selected from the group consisting of a carboxy group, a sulfo group and a group represented by the following formula (11) in the same or different polymer as the polymer (A1). It is preferable to contain.

(In the formula (11), R ²³ is a hydrogen atom, a halogen atom, a nitro group, an alkyl group, a monovalent alicyclic hydrocarbon group, an alkoxy group, an acyl group, an aralkyl group or an aryl group. The above alkyl group A part or all of hydrogen atoms of the alicyclic hydrocarbon group, alkoxy group, acyl group, aralkyl group and aryl group may be substituted, R ²⁴ is —C (═O) —R ²⁵ , ^{_{-S (= O) 2 -R 26}} , -R 27 .R 25 and ^{R 26} is -CN or ^-R 28 -NO ₂ are each independently a hydrogen atom, an alkyl group, fluorinated alkyl group, 1 A valent alicyclic hydrocarbon group, an alkoxy group, a cyano group, a cyanomethyl group, an aralkyl group or an aryl group, provided that R ²⁵ or R ²⁶ and R ²³ are bonded to each other to form a ring structure. Good, R ²⁷ and R ²⁸ is each independently a single bond, a methylene group or an alkylene group having 2 to 5 carbon atoms.)

  [A] Removal of the liquid immersion upper layer film formed from the composition for forming a liquid immersion upper layer film because the polymer component contains a highly polar sulfo group, carboxy group or group represented by the above formula (11) Property and peeling resistance are improved. As a result, when the liquid immersion upper layer film forming composition is used, development defects such as a bridge defect and a blob defect can be further suppressed, and a resist pattern that is superior in pattern shape can be formed.

  [B] The solvent preferably contains an ether solvent. Since the resist film is difficult to dissolve in an ether solvent, the resist film surface is eroded by the solvent in the composition for forming an upper liquid immersion film when the composition for forming the upper liquid film is applied on the resist film. Can prevent the inconvenience.

The resist pattern forming method of the present invention comprises:
(1) forming a resist film on the substrate;
(2) A step of laminating an immersion upper film on the resist film using the composition for forming an immersion upper film;
(3) immersion exposure of the resist film on which the liquid immersion upper layer film is laminated by irradiation of radiation through a photomask; and (4) a step of developing the immersion exposed resist film.

  According to the resist pattern forming method, development defects such as bridge defects and blob defects can be suppressed, and a resist pattern that is more excellent in pattern shape can be formed.

  According to the composition for forming a liquid immersion upper layer film and the method for forming a resist pattern of the present invention, a liquid immersion upper film sufficiently satisfying basic characteristics such as water repellency and solubility in a developer can be formed, and resist pattern formation can be performed. Development defects such as bridge defects and blob defects can be suppressed, and a resist pattern having an excellent pattern shape can be formed. Therefore, they can be suitably used for lithography processes in the manufacture of electronic devices that will be increasingly miniaturized in the future.

<Composition for forming liquid immersion upper layer film>
The composition for forming an immersion upper layer film of the present invention contains [A] a polymer component and [B] a solvent. The composition for forming a liquid immersion upper layer film may contain an optional component in addition to the [A] polymer component and the [B] solvent, as long as the effects of the present invention are not impaired. Hereinafter, each component will be described in detail.

<[A] Polymer component>
[A] The polymer component includes a polymer (A1). This polymer (A1) is a polymer having a structural unit (I) containing a group represented by the above formula (1). [A] The polymer component may consist of only the polymer (A1), and may contain a polymer (A2) having no structural unit (I) in addition to the polymer (A1). . [A] The polymer component may contain one or more polymers.
[A] When the polymer component contains a group having an alkali-dissociable group represented by the above formula (1), the liquid immersion upper film formed from the liquid immersion upper film forming composition has water repellency. In addition, the solubility in an alkali developer is good. As a result, development defects such as bridge defects and blob defects in resist pattern formation can be suppressed, and a resist pattern having an excellent pattern shape can be formed.

  [A] The polymer component is selected from the group consisting of a fluorinated alkyl group and a fluorinated hydroxyalkyl group in addition to the structural unit (I) in the same or different polymer as the polymer (A1). A structural unit (II) that contains at least one kind of group and does not contain the group represented by the above formula (1), and / or a sulfo group, a carboxy group, and a group represented by the above formula (11). It is preferable to further have at least one structural unit (III) selected from the group. Moreover, the [A] polymer component may have another structural unit other than these structural units, unless the effect of this invention is impaired. In addition, the [A] polymer component may have each structural unit individually by 1 type, and may have 2 or more types.

  The polymer (A1) contains at least one group selected from the group consisting of a fluorinated alkyl group and a fluorinated hydroxyalkyl group, in addition to the structural unit (I), and in the formula (1) It is preferable to further have a structural unit (II) that does not contain the represented group. In addition, the polymer (A1) may have other structural units in addition to these structural units as long as the effects of the present invention are not impaired. In addition, the polymer (A1) may have each structural unit individually by 1 type, and may have 2 or more types.

  As the polymer (A2) having no structural unit (I), at least one structural unit (III) selected from the group consisting of a sulfo group, a carboxy group and a group represented by the above formula (11) is used. It is preferable to have.

[A] In the polymer component, when the polymer (A2) different from the polymer (A1) contains a highly polar sulfo group, carboxy group or group represented by the above formula (11), the immersion upper layer In the film-forming composition, the polymer (A1) component having high water repellency can be unevenly distributed on the surface of the liquid immersion upper layer film. Thereby, the liquid immersion upper film formed from the liquid immersion upper film forming composition can sufficiently satisfy basic characteristics such as water repellency. Further, when the polymer (A2) contains a highly polar sulfo group, carboxy group or group represented by the above formula (11), the polymer (A2) is excellent in solubility in alkali during alkali development and has the effect of suppressing defects during development. Is expensive. When the polymer (A2) has the structural unit (III), it contains at least one group selected from the group consisting of a fluorinated alkyl group and a fluorinated hydroxyalkyl group in addition to the structural unit (III), and It is preferable to further have a structural unit (II) that does not contain a group represented by the above formula (1). The polymer (A2) may have other structural units as long as the effects of the present invention are not impaired. In addition, the polymer (A2) may have each structural unit individually by 1 type, and may have 2 or more types.
Hereinafter, each structural unit will be described in detail.

[Structural unit (I)]
The structural unit (I) is a structural unit containing a group represented by the above formula (1). The structural unit (I) may have one or a plurality of groups represented by the above formula (1) in the structural unit, or may have a plurality of types.

In the above formula (1), R ¹ is an alkali dissociable group. R ² is an (n + 1) -valent linking group. A is —CO—O— *, —SO ₂ —O— *, an oxygen atom, or —NR ³ —. R ³ is a hydrogen atom or an alkali dissociable group. * Indicates a site binding to ^{R 1.} However, when A is an oxygen atom, the site directly connected to A in R ² is not a carbonyl group or a sulfonyl group. n is an integer of 1 to 3. However, when n is 2 or more, the plurality of R ¹ and A may be the same or different.

The alkali dissociable group represented by R ¹ is a group that is dissociated by an alkali developer used in the development step of the resist pattern forming method, and does not contain a fluorine atom even if it contains a fluorine atom. Although it may be a thing and it is not specifically limited, It is a C1-C20 monovalent hydrocarbon group, group represented by the said Formula (3), or group represented by the said Formula (4). Is preferred. When the alkali dissociable group for R ¹ is the specific group, the water repellency of the liquid immersion upper film formed from the liquid immersion upper film forming composition can be improved. Further, when the alkali dissociable group contains a fluorine atom, in the development process, the alkali dissociable group containing the fluorine atom is dissociated by the alkali developer, so that the fluorine atom content is reduced, and bridge defects, blob defects, etc. Development defects can be further suppressed.

Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms represented by R ¹ include an alkyl group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 4 to 20 carbon atoms, and 6 to 20 carbon atoms. And aromatic hydrocarbon groups.

  Examples of the alkyl group having 1 to 10 carbon atoms include methyl group, ethyl group, propyl group, n-butyl group, i-butyl group, n-pentyl group, i-pentyl group, n-hexyl group, i- A hexyl group etc. are mentioned.

  Examples of the alicyclic hydrocarbon group having 4 to 20 carbon atoms include a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a norbornyl group, an adamantyl group, and the like.

  As said C6-C20 aromatic hydrocarbon group, a phenyl group, a naphthyl group, etc. are mentioned, for example.

  Among these, the monovalent hydrocarbon group is preferably an alkyl group having 1 to 10 carbon atoms, more preferably a methyl group or an ethyl group, and further preferably a methyl group.

In said formula (3), R < ⁶ > -R < ⁹ > is a hydrogen atom, a fluorine atom, or a perfluoroalkyl group. However, at least one of R ^{6 to} R ⁹ is a fluorine atom or a perfluoroalkyl group. R ¹⁰ is a hydrogen atom, a fluorine atom or a monovalent organic group.

Examples of the perfluoroalkyl group represented by R ^{6 to} R ⁹ include a trifluoromethyl group, a perfluoroethyl group, a perfluoro n-propyl group, a perfluoro i-propyl group, a perfluoro n-butyl group, Examples include a perfluoro i-butyl group, a perfluoro t-butyl group, and a perfluorocyclohexylmethyl group.

Examples of the monovalent organic group represented by R ¹⁰ include an alkyl group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 4 to 20 carbon atoms, and an aromatic hydrocarbon group having 6 to 20 carbon atoms. Is mentioned.

  Examples of the alkyl group having 1 to 10 carbon atoms include methyl group, ethyl group, propyl group, n-butyl group, i-butyl group, n-pentyl group, i-pentyl group, n-hexyl group, i- A hexyl group etc. are mentioned.

  Examples of the alicyclic hydrocarbon group having 4 to 20 carbon atoms include a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a norbornyl group, an adamantyl group, and the like.

  As said C6-C20 aromatic hydrocarbon group, a phenyl group, a naphthyl group, etc. are mentioned, for example.

  Examples of the group represented by the above formula (3) include 2,2-difluoroethyl group, 2,2,2-trifluoroethyl group, 2,2,3,3,3-pentafluoroethyl group, 2 , 2,3,3,4,4,4-hexafluoroethyl group, 1,1,1-trifluoro-2-propyl group, 1,1,1,3,3,3-hexafluoro-2-propyl group Etc. Among these, 2,2,2-trifluoroethyl group, 2,2,3,3,3-pentafluoroethyl group, 1,1,1,3,3,3-hexafluoro-2-propyl group Is preferred.

In the above formula (4), a is 0 or 1. b is an integer of 0-5. R ¹¹ is a monovalent organic group which may contain a fluorine atom or a fluorine atom. However, when b is 2 or more, the plurality of R ¹¹ may be the same or different. Further, at least one R ¹¹ is preferably a fluorine atom or a monovalent organic group containing a fluorine atom.

Examples of the monovalent organic group that may contain a fluorine atom represented by R ¹¹ include an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, and an acyl group having 1 to 10 carbon atoms. And an acyloxy group having 1 to 10 carbon atoms. Note that some or all of the hydrogen atoms contained in these groups may be substituted with fluorine atoms.

Examples of the alkyl group having 1 to 10 carbon atoms, for example, such as the same group as the alkyl group having 1 to 10 carbon atoms represented by R ¹ can be mentioned.

  As said C1-C10 alkoxy group, a methoxy group, an ethoxy group, n-propoxy group, i-propoxy group, n-butoxy group, t-butoxy group etc. are mentioned, for example.

  Examples of the acyl group having 1 to 10 carbon atoms include formyl group, acetyl group, propionyl group, butyryl group, valeryl group, trioyl group, caproyl group and the like.

  Examples of the acyloxy group having 1 to 10 carbon atoms include an acetoxy group, an ethylyloxy group, a butyryloxy group, a t-butyryloxy group, a t-amylyloxy group, an n-hexane carbonyloxy group, and an n-octane carbonyloxy group. It is done.

  As a, 1 is preferable. As b, the integer of 0-3 is preferable, the integer of 0-2 is more preferable, and 1 and 2 are further more preferable.

  Examples of the group represented by the above formula (4) include phenyl group, tolyl group, fluorophenyl group, fluorobenzyl group, difluorobenzyl group, trifluoromethylbenzyl group and the like. Among these, a difluorobenzyl group and a trifluoromethylbenzyl group are preferable.

Among these, R ¹ is an alkyl group having 1 to 4 carbon atoms, R ⁷ , R ⁹ and R ¹⁰ in the above formula (3) are a fluorine atom or a trifluoromethyl group, and R ⁶ is a hydrogen atom. More preferably, a group in which R ⁸ is a hydrogen atom or a trifluoromethyl group, or a fluorinated benzyl group.

Examples of the (n + 1) -valent linking group represented by R ² include (n + 1) -valent hydrocarbon groups having 1 to 20 carbon atoms, (n + 1) -valent fluorinated hydrocarbon groups having 1 to 20 carbon atoms, -O -, - S -, - COO -, - OCO -, - SO 2 -, - CO-, and a group formed by combining these.

  Examples of the (n + 1) -valent hydrocarbon group having 1 to 20 carbon atoms include (n + 1) -valent linear or branched hydrocarbon groups having 1 to 10 carbon atoms, and (n + 1) -valent hydrocarbon groups having 4 to 20 carbon atoms. Examples thereof include alicyclic hydrocarbon groups and (n + 1) -valent aromatic hydrocarbon groups having 6 to 20 carbon atoms.

  Examples of the (n + 1) -valent linear or branched hydrocarbon group having 1 to 10 carbon atoms include (n + 1) hydrogen atoms from alkanes such as methane, ethane, propane, butane, pentane, hexane, and octane. Examples include groups other than atoms. Of these, a methylene group, a methanetriyl group, an ethanetriyl group, and an i-propanetetrayl group are preferable.

Examples of the (n + 1) -valent alicyclic hydrocarbon group having 4 to 20 carbon atoms include:
A group obtained by removing (n + 1) hydrogen atoms from a monocyclic saturated hydrocarbon such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclodecane, methylcyclohexane, ethylcyclohexane;
A group obtained by removing (n + 1) hydrogen atoms from a monocyclic unsaturated hydrocarbon such as cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, cyclodecene, cyclopentadiene, cyclohexadiene, cyclooctadiene, cyclodecadiene;
Bicyclo [2.2.1] heptane, bicyclo [2.2.2] octane, tricyclo [5.2.1.0 ^2,6 ] decane, tetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] a group obtained by removing (n + 1) hydrogen atoms from a polycyclic saturated hydrocarbon such as dodecane or adamantane;
Bicyclo [2.2.1] heptene, bicyclo [2.2.2] octene, tricyclo [5.2.1.0 ^2,6 ] decene, tetracyclo [6.2.1.1 ^3,6 . And a group obtained by removing (n + 1) hydrogen atoms from a polycyclic unsaturated hydrocarbon such as 0 ^2,7 ] dodecene.

  Examples of the (n + 1) -valent aromatic hydrocarbon group having 6 to 20 carbon atoms include groups obtained by removing (n + 1) hydrogen atoms from aromatic hydrocarbons such as benzene, toluene, xylene, naphthalene, and anthracene. Is mentioned.

  In addition, as the (n + 1) -valent fluorinated hydrocarbon group having 1 to 20 carbon atoms, at least a part of the hydrogen atoms of the groups exemplified as the (n + 1) -valent hydrocarbon group having 1 to 20 carbon atoms is used. And a group substituted with a fluorine atom.

Moreover, with these hydrocarbon groups and fluorinated hydrocarbon groups, -O -, - S -, - COO -, - OCO -, - SO 2 -, - CO-, at least one selected from the group consisting of Examples of the group formed by combining with the above group include -O-, -S-, -COO-, -OCO-, -SO _2-in the ring structure of the alicyclic hydrocarbon group and the fluorinated alicyclic hydrocarbon group. And those containing at least one group selected from the group consisting of -CO-.

  Examples of the ring structure composed of -O- and a hydrocarbon group having 1 to 20 carbon atoms include a cyclic ether structure having 3 to 8 carbon atoms.

  Examples of the ring structure composed of -S- and a hydrocarbon group having 1 to 20 carbon atoms include a cyclic thioether structure having 3 to 8 carbon atoms.

  Examples of the ring structure composed of the -COO- and a hydrocarbon group having 1 to 20 carbon atoms include a lactone structure having 3 to 8 carbon atoms.

  Examples of the ring structure composed of -CO- and a hydrocarbon group having 1 to 20 carbon atoms include a cyclic ketone structure having 3 to 8 carbon atoms.

Examples of the ring structure composed of the —SO ₂ — and the hydrocarbon group having 1 to 20 carbon atoms include a cyclic sulfonyl structure having 3 to 8 carbon atoms.

When the group represented by A is —NR ³ —, the alkali dissociable group of R ³ is not particularly limited as long as it is a group dissociated by an alkali developer used in the development step of the resist pattern forming method. Examples thereof include the same groups as the alkali dissociable group represented by R ¹ above.

  The A is preferably —CO—O—.

The structural unit (I) is preferably a structural unit represented by the above formula (2) (hereinafter also referred to as “structural unit (I-1)”). In the formula (2), R ⁵ represents a hydrogen atom, a methyl group, a hydroxymethyl group or a trifluoromethyl group. R ⁴ is —CO—O—, —O—CO—O—, —O—, —SO ₂ —, —CO—NH— or —SO ₂ NH—. n, R ¹ and R ² are as defined in the above formula (1).

  Examples of the structural unit (I) include structural units represented by the following formulas (1-1) to (1-15).

In the above formulas (1-1) to (1-15), R ⁵ has the same meaning as the above formula (2).

  Among these, the structural units represented by the above formulas (1-1) to (1-4), the structural unit represented by the above formula (1-8), and the above formulas (1-11) to (1-15). ) Is preferred.

  As a monomer which gives structural unit (I), the compound etc. which are represented by a following formula are mentioned, for example.

[A] The content ratio of the structural unit (I) in the polymer component is usually 0.1 mol% or more and 50 mol% or less with respect to all the structural units constituting the [A] polymer component, preferably Is 0.3 mol% or more and 20 mol% or less, more preferably 0.5 mol% or more and 10 mol% or less. By setting the content ratio of the structural unit (I) to 0.1 mol% or more, the liquid immersion upper layer film formed from the liquid immersion upper layer film-forming composition has further excellent water repellency, and 50 mol % Or less, the [A] polymer component is excellent in solubility in an alkali developer and also excellent in peeling resistance.
The content ratio of the structural unit (I) in the polymer (A1) is preferably from 0.1 mol% to 30 mol%, more preferably from 0.5 mol% to 20 mol%, and more preferably from 1 mol% to 10 mol. % Or less is more preferable. By setting the content ratio of the structural unit (I) in the above range, the liquid immersion upper layer film obtained from the liquid immersion upper layer film-forming composition sufficiently satisfies the water repellency, and has bridge defects and blobs in resist pattern formation. Development defects such as defects can be further suppressed.

[Structural unit (II)]
The structural unit (II) includes at least one group selected from the group consisting of a fluorinated alkyl group and a fluorinated hydroxyalkyl group, and does not include the group represented by the formula (1). . [A] When the polymer component further has a structural unit (II) containing a fluorine atom, the liquid immersion upper film formed from the liquid immersion upper film forming composition has further excellent water repellency. The basic characteristics as a liquid immersion upper film can be sufficiently satisfied.

  Examples of the structural unit (II) include structural units represented by the following formulas (5) to (7) (hereinafter also referred to as “structural units (II-1) to (II-3)”).

In said formula (5), R < ¹² > is a hydrogen atom, a methyl group, a fluorine atom, or a trifluoromethyl group. R ¹³ is a divalent linking group.
In the above formula (6), R ¹⁴ is a hydrogen atom, a methyl group, a fluorine atom or a trifluoromethyl group. R ¹⁵ is a fluorinated alkyl group having 1 to 10 carbon atoms or a fluorinated alicyclic hydrocarbon group having 3 to 10 carbon atoms.
In the above formula (7), R ¹⁶ is a hydrogen atom, a methyl group, a fluorine atom or a trifluoromethyl group. R ¹⁷ is a divalent linking group. R ¹⁸ is a fluorinated alkyl group having 1 to 20 carbon atoms.

In the above formula (5), examples of the divalent linking group represented by R ¹³ include a linear or branched divalent hydrocarbon group having 1 to 12 carbon atoms and 2 having 4 to 12 carbon atoms. Valent alicyclic hydrocarbon groups, groups formed by combining these, and the like.

  Examples of the linear or branched divalent hydrocarbon group having 1 to 12 carbon atoms include a methylene group, an ethylene group, an n-propylene group, an i-propylene group, an n-butylene group, and an i-butylene group. , N-pentylene group, i-pentylene group and the like. Among these, a C1-C3 bivalent hydrocarbon group is preferable and a methylene group, ethylene group, n-propylene group, and i-propylene group are more preferable.

  Examples of the divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms include monocyclic alicyclic hydrocarbon groups such as cyclobutylene group, cyclopentylene group, cyclohexylene group, and cyclooctylene group; norbornylene And a polycyclic alicyclic hydrocarbon group having a 2- to 4-membered ring such as a group and an adamantylene group. Of these, norbornylene group and adamantylene group are preferable.

In the above formula (6), examples of the fluorinated alkyl group having 1 to 10 carbon atoms represented by R ¹⁵ include a methyl group, an ethyl group, a propyl group, an n-butyl group, an i-butyl group, and an n-pentyl group. , A group in which at least one hydrogen atom of an alkyl group such as i-pentyl group, n-hexyl group and i-hexyl group is substituted with a fluorine atom, and the like.

Examples of the fluorinated alicyclic hydrocarbon group having 3 to 10 carbon atoms represented by R ¹⁵ include a hydrogen atom contained in a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a norbornyl group, an adamantyl group, and the like. And a group in which at least one of is substituted with a fluorine atom.

In the above formula (7), examples of the divalent linking group represented by R ¹⁷ include the same groups as those exemplified as the divalent linking group represented by R ¹³ .

Examples of the fluorinated alkyl group having 1 to 20 carbon atoms represented by R ¹⁸ include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, and an n-pentyl group. Group, i-pentyl group, n-hexyl group, i-hexyl group, n-decyl group, i-decyl group, n-dodecyl group, i-dodecyl group, etc. And a group substituted with.

  Examples of the structural unit (II-1) include structural units represented by the following formulas (2-1) to (2-8).

R < ¹² > is synonymous with the said Formula (5) in said formula (2-1)-(2-8).

  Among these, the structural units represented by the above formulas (2-4) and (2-8) are preferable.

  Examples of the structural unit (II-2) include structural units represented by the following formulas (2-9) to (2-14).

In the above formulas (2-9) to (2-14), R ¹⁴ has the same meaning as the above formula (6).

  Among these, the structural units represented by the above formulas (2-9) and (2-11) are preferable.

  Examples of the structural unit (II-3) include structural units represented by the following formulas (2-15) to (2-17).

In the above formulas (2-15) to (2-17), R ¹⁶ has the same meaning as in the above formula (7).

  Among these, the structural unit represented by the above formula (2-15) is preferable.

  As a monomer which gives structural unit (II), the compound etc. which are represented by a following formula are mentioned, for example.

  [A] The content ratio of the structural unit (II) in the polymer component is preferably 30 mol% or more and less than 100 mol%, preferably 40 mol% or more and 99 mol% with respect to all the structural units constituting the [A] polymer component. 0.5 mol% or less is more preferable, and 50 mol% or more and 99 mol% or less is more preferable. [A] By making the content rate of structural unit (II) in a polymer component into the said range, it is excellent by the water repellency and removability of the liquid immersion upper layer film formed from the said liquid immersion upper layer film formation composition.

  When the polymer (A1) contains the structural unit (II), the content ratio of the structural unit (II) is preferably 40 mol% or more and less than 100 mol%, more preferably 60 mol% or more and less than 100 mol%, 80 mol% or more and less than 10 mol% is more preferable. By making the content rate of structural unit (II) into the said range, the liquid immersion upper film obtained from the said liquid immersion upper film formation composition can fully satisfy water repellency.

  When the polymer (A2) contains the structural unit (II), the content of the structural unit (II) is preferably 30 mol% or more and less than 100 mol%, more preferably 40 mol% or more and 99.5 mol% or less. Preferably, it is 50 mol% or more and 99 mol% or less. By setting the content ratio of the structural unit (II) in the above range, basic characteristics such as water repellency of the liquid immersion upper layer film obtained from the liquid immersion upper layer film forming composition can be sufficiently satisfied.

[Structural unit (III)]
The structural unit (III) is a structural unit containing at least one group selected from the group consisting of a carboxy group, a sulfo group, and a group represented by the above formula (11).
Among the structural units (III), the structural unit containing a sulfo group (hereinafter also referred to as “structural unit (III-1)”) is, for example, a structural unit represented by the following formula (8) (hereinafter referred to as “structural unit”). (III-1-1) ") and the like.

In the formula (8), R ¹⁹ is a hydrogen atom, a methyl group, a fluorine atom or a trifluoromethyl group. R ²⁰ is a single bond or a divalent linking group.

Examples of the divalent linking group represented by R ²⁰ include an oxygen atom, a sulfur atom, a divalent linear or branched hydrocarbon group having 1 to 6 carbon atoms, and a divalent group having 4 to 12 carbon atoms. Alicyclic hydrocarbon groups, divalent aromatic hydrocarbon groups having 6 to 12 carbon atoms, carbonyl groups, ester groups, —NH—, groups formed by combining these groups, and the like.

  As said C1-C6 bivalent linear or branched hydrocarbon group, a methylene group, an ethanediyl group, a propanediyl group, a butanediyl group etc. are mentioned, for example.

  Examples of the divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms include a cyclobutanediyl group, a cyclopentanediyl group, a cyclohexanediyl group, a norbornylene group, and an adamantylene group.

  Examples of the divalent aromatic hydrocarbon group having 6 to 12 carbon atoms include a phenylene group and a naphthylene group.

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

In the above formula, R ¹⁹ has the same meaning as in the above formula (8).

  Among these, a structural unit derived from vinyl sulfonic acid and a structural unit derived from (meth) acryloylaminopropyl sulfonic acid are preferable.

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

  Among the structural units (III), examples of the structural unit containing a carboxy group (hereinafter also referred to as “structural unit (III-2)”) include a structural unit represented by the following formula (9) (hereinafter referred to as “structural unit”). (Also referred to as “(III-2-1)”), a structural unit represented by the following formula (10) (hereinafter also referred to as “structural unit (III-2-2)”), and the like.

In the above formulas (9) and (10), R ²¹ represents a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ²² is a divalent linking group.

Examples of the divalent linking group represented by R ²² include a linear or branched divalent hydrocarbon group having 1 to 6 carbon atoms and a divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms. Groups, divalent aromatic hydrocarbon groups having 6 to 12 carbon atoms, groups formed by combining these groups with ester groups, and the like.

The said C1-C6 linear or branched bivalent hydrocarbon group, C4-C12 bivalent alicyclic hydrocarbon group, C6-C12 bivalent aromatic hydrocarbon the group can be applied to description of each of the groups represented by R ^20.

  Examples of the structural unit (III-2-1) include a structural unit represented by the following formula.

In said formula, R < ²¹ > is synonymous with the said Formula (9).

  Of these, structural units derived from carboxycyclohexyl (meth) acrylate are preferred.

  Examples of the monomer that gives the structural unit (III-2-1) or the structural unit (III-2-2) include compounds represented by the following formulas.

  Next, of the structural unit (III), the structural unit containing the group represented by the above formula (11) (hereinafter also referred to as “structural unit (III-3)”) will be described.

In the above formula (11), R ²³ represents a hydrogen atom, a halogen atom, a nitro group, an alkyl group, a monovalent alicyclic hydrocarbon group, an alkoxy group, an acyl group, an aralkyl group or an aryl group. Some or all of the hydrogen atoms of the alkyl group, alicyclic hydrocarbon group, alkoxy group, acyl group, aralkyl group and aryl group may be substituted. R ²⁴ is —C (═O) —R ²⁵ , —S (═O) ₂ —R ²⁶ , —R ²⁷ —CN or —R ²⁸ —NO ₂ . R ²⁵ and R ²⁶ are each independently a hydrogen atom, an alkyl group, a fluorinated alkyl group, a monovalent alicyclic hydrocarbon group, an alkoxy group, a cyano group, a cyanomethyl group, an aralkyl group or an aryl group. However, R ²⁵ or R ²⁶ and R ²³ may be bonded to each other to form a ring structure. R ²⁷ and R ²⁸ are each independently a single bond, a methylene group or an alkylene group having 2 to 5 carbon atoms.

The halogen atom represented by R ^23, for example, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among these, a fluorine atom and a chlorine atom are preferable.

The alkyl group represented by ^{R 23,} for example, a methyl group, an ethyl group, n- propyl group, a branched alkyl group such as n- butyl group; i-propyl, i- butyl, sec- Examples thereof include branched alkyl groups such as a butyl group and a t-butyl group. As said alkyl group, a C1-C20 alkyl group is preferable.

Examples of the monovalent alicyclic hydrocarbon group represented by R ²³ include a monocyclic alicyclic hydrocarbon group such as a cyclopentyl group and a cyclohexyl group; an adamantyl group, a norbornyl group, a tetracyclodecanyl group, and the like. And the polycyclic alicyclic hydrocarbon group. As said alicyclic hydrocarbon group, a C3-C20 alicyclic hydrocarbon group is preferable.

The alkoxy group represented by R ^23, for example, a methoxy group, an ethoxy group, and the like. As said alkoxy group, a C1-C20 alkoxy group is preferable.

The acyl group represented by R ^23, for example, an acetyl group, a propionyl group and the like. As said acyl group, a C2-C20 acyl group is preferable.

Examples of the aralkyl group represented by R ²³ include a benzyl group, a phenethyl group, and a naphthylmethyl group. As said aralkyl group, a C7-C12 aralkyl group is preferable.

The aryl group represented by R ^23, for example, a phenyl group, a tolyl group, dimethylphenyl group, a 2,4,6-trimethylphenyl group, a naphthyl group, and the like. As said aryl group, a C6-C10 aryl group is preferable.

Examples of the substituent that the alkyl group, monovalent alicyclic hydrocarbon group, alkoxy group, acyl group, aralkyl group and aryl group represented by R ²³ may have include a fluorine atom and a chlorine atom. And halogen atoms such as hydroxyl group, nitro group, cyano group and the like.

As R ²³ , among these, from the viewpoint of balancing the developer solubility and the peeling resistance of the upper film formed from the immersion upper film forming composition, among them, a hydrogen atom, an alkyl group having 1 to 5 carbon atoms. , An alkoxy group having 1 to 5 carbon atoms and an acyl group having 2 to 5 carbon atoms are preferable, and a hydrogen atom, a methyl group, an ethyl group, and an acetyl group are more preferable.

When R ²⁴ is —C (═O) —R ²⁵ and —S (═O) ₂ —R ²⁶ , the alkyl group represented by R ²⁵ and R ²⁶ , a monovalent alicyclic hydrocarbon group, and an alkoxy group as the aralkyl group and the aryl group, for example, such as the same groups as those exemplified as the respective groups of R ²³ can be mentioned. Examples of the fluorinated alkyl group represented by R ²⁵ and R ²⁶ include groups in which at least one of the hydrogen atoms of the groups exemplified as the alkyl group for R ²³ is substituted with a fluorine atom. Among these, as R ²⁵ and R ²⁶ , a hydrogen atom and an alkyl group are preferable, and a hydrogen atom, a methyl group, and an ethyl group are more preferable.

The group containing a ring structure formed by combining R ²⁵ or R ²⁶ and R ²³ with each other includes a carbon atom to which R ²⁵ or R ²⁶ and R ²³ are bonded, and having an oxo group. A divalent alicyclic hydrocarbon group of 5 to 12 is preferred.

When R ²⁴ is —R ²⁷ —CN and —R ²⁸ —NO ₂ , R ²⁷ and R ²⁸ are preferably a single bond, a methanediyl group or an ethanediyl group.

  As group represented by said Formula (11), group represented by following formula (11-1)-(11-8) is preferable.

  In the above formulas (11-1) to (11-8), * represents a binding site.

  The structural unit (III-3) is derived from, for example, a (meth) acrylic acid ester derivative, a (meth) acrylamide derivative, a vinyl ether derivative, an olefin derivative, a styrene derivative, or the like having a group represented by the above formula (11). Examples include structural units. In this, the structural unit derived from a (meth) acrylic acid ester derivative is preferable. That is, as the structural unit (III-3), a structural unit represented by the following formula (12) (hereinafter also referred to as “structural unit (III-3-1)”) is preferable.

In the above formula ^{(12), R 23} and ^{R 24} is as defined in the above formula (11). m is an integer of 1-3. If R ²³ and ^{R 24} are a plurality of each of the plurality of ^{R 23} and ^{R 24} may be the same as or different from each other. R ³⁰ is a (m + 1) -valent linking group. R ²⁹ is a hydrogen atom, a methyl group, a fluorine atom or a trifluoromethyl group.

R ²⁹ is preferably a hydrogen atom or a methyl group, more preferably a methyl group, from the viewpoint of the copolymerizability of the monomer that gives the structural unit (III-3).

Examples of the (m + 1) -valent linking group represented by R ³⁰ include an alkanediyl group, a divalent alicyclic hydrocarbon group, and an alkenediyl group as a divalent linking group (when n is 1). And arenediyl groups. Note that some or all of the hydrogen atoms contained in these groups may be substituted with a halogen atom such as a fluorine atom or a chlorine atom, a cyano group, or the like.

  Examples of the alkanediyl group include methanediyl group, ethanediyl group, propanediyl group, butanediyl group, hexanediyl group, and octanediyl group. As said alkanediyl group, a C1-C8 alkanediyl group is preferable.

  Examples of the divalent alicyclic hydrocarbon group include monocyclic alicyclic hydrocarbon groups such as cyclopentanediyl group and cyclohexanediyl group; and polycyclic alicyclic groups such as norbornanediyl group and adamantanediyl group. A hydrocarbon etc. are mentioned. As said bivalent alicyclic hydrocarbon group, a C5-C12 alicyclic hydrocarbon group is preferable.

  Examples of the alkenediyl group include an ethenediyl group, a propenediyl group, and a butenediyl group. As said alkenediyl group, a C2-C6 alkenediyl group is preferable.

  Examples of the arenediyl group include a phenylene group, a tolylene group, and a naphthylene group. As the above arenediyl group, an arenediyl group having 6 to 15 carbon atoms is preferable.

Among these, as R ³⁰ , an alkanediyl group, a divalent alicyclic hydrocarbon group is preferable, an alkanediyl group having 1 to 4 carbon atoms, and a divalent alicyclic hydrocarbon group having 6 to 11 carbon atoms. Is more preferable. When R ³⁰ is a divalent alicyclic hydrocarbon group, it is preferable from the viewpoint of improving the water repellency of the resulting upper layer film.

  As the structural unit (III-3-1), structural units represented by the following formulas (12-1) to (12-10) are preferable, and a structural unit represented by the following formula (12-7) is more preferable. .

In the formulas (12-1) to (12-10), R ²⁹ has the same meaning as the formula (12).

  [A] The content ratio of the structural unit (III) in the polymer component is preferably 0 mol% to 40 mol%, preferably 0.5 mol% to the total structural unit constituting the [A] polymer component. 30 mol% is more preferable and 1 mol%-25 mol% are further more preferable. [A] By making the content rate of structural unit (III) in a polymer component into the said range, the removability and peeling resistance of the liquid immersion upper film formed from the said liquid immersion upper film formation composition improve.

  When the polymer (A2) contains the structural unit (III), the content ratio of the structural unit (III) is 0.1 mol% or more when the polymer (A2) contains the structural unit (II). 20 mol% or less is preferable, 0.5 mol% or more and 10 mol% or less is more preferable, and 1 mol% or more and 5 mol% or less is more preferable. When the polymer (A2) does not contain the structural unit (II), the content of the structural unit (III) is preferably 70 mol% or more and 100 mol% or less, more preferably 90 mol% or more and 100 mol% or less. preferable. By setting the content ratio of the structural unit (III) in the above range, in the liquid immersion upper film obtained from the liquid immersion upper film forming composition, the polymer (A1) component having high water repellency is added to the surface of the liquid upper film. Can be unevenly distributed. Accordingly, the liquid immersion upper layer film formed from the liquid immersion upper layer film forming composition can sufficiently satisfy basic characteristics such as water repellency and has excellent peeling resistance. Moreover, since the content rate of structural unit (III) is made into the said range, since it is excellent in the solubility to the alkali at the time of alkali image development, the effect of the defect suppression at the time of image development is high.

[Other structural units]
[A] In addition to the structural units (I) to (III), the polymer component includes other structural units such as propyl (meth) acrylate and butyl (meth) acrylate for the purpose of improving water repellency, ( You may have the structural unit derived from alkyl (meth) acrylates, such as a lauryl acrylate. Further, for the purpose of controlling the molecular weight of the polymer, the glass transition point, the solubility in a solvent, and the like, it may have a structural unit having an acid dissociable group that can be removed by the action of an acid.

<Synthesis Method of Polymers (A1) and (A2)>
The polymers (A1)) and (A2) can be produced, for example, by polymerizing monomers corresponding to predetermined respective structural units in a suitable solvent using a radical polymerization initiator. For example, a method of dropping a solution containing a monomer and a radical initiator into a reaction solvent or a solution containing the monomer to cause a polymerization reaction, a solution containing the monomer, and a solution containing the radical initiator Separately, a method of dropping a reaction solvent or a monomer-containing solution into a polymerization reaction, a plurality of types of solutions containing each monomer, and a solution containing a radical initiator, It is preferable to synthesize by a method such as a method of dropping it into a reaction solvent or a solution containing a monomer to cause a polymerization reaction.

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

  Although the reaction temperature in the said polymerization should just be suitably determined according to the kind of radical initiator, it is 40 to 150 degreeC normally, and 50 to 120 degreeC is preferable. The reaction time is usually 1 hour to 48 hours, preferably 1 hour to 24 hours.

  Examples of the radical initiator used in the polymerization include azobisisobutyronitrile (AIBN), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2 -Cyclopropylpropionitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylpropionitrile) and the like. Two or more of these initiators may be mixed and used.

  The polymer obtained by the polymerization reaction is preferably recovered by a reprecipitation method. That is, after completion of the polymerization reaction, the target resin 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.

  The weight average molecular weight (Mw) of the polymers (A1) and (A2) by gel permeation chromatography (GPC) is preferably 1,000 to 100,000, more preferably 2,000 to 50,000. 30,000 to 30,000 are more preferable. By setting the Mw of the polymers (A1) and (A2) within the specific range, film loss can be suppressed and the LWR of the resulting pattern can be made an excellent value.

  The ratio (Mw / Mn) of Mw and number average molecular weight (Mn) of the polymers (A1) and (A2) is usually 1 to 5, preferably 1 to 3, and more preferably 1 to 2. By making Mw / Mn into such a specific range, film loss can be suppressed and the LWR of the resulting pattern can be made an excellent value.

  In this specification, Mw and Mn are GPC columns (2 G2000HXL, 1 G3000HXL, 1 G4000HXL, or more from Tosoh), flow rate 1.0 mL / min, elution solvent tetrahydrofuran, sample concentration 1.0 mass. %, A sample injection amount of 100 μL, and a column temperature of 40 ° C., using a differential refractometer as a detector and a value measured by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard.

<[B] Solvent>
The composition for forming a liquid immersion upper layer film contains a [B] solvent. [B] The solvent is not particularly limited as long as the [A] polymer component and the optional component can be dissolved. [B] Examples of the solvent include alcohol solvents, ether solvents, ketone solvents, amide solvents, ester solvents, hydrocarbon solvents, and mixed solvents thereof.

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

Examples of ether solvents include polyhydric alcohol partial alkyl ether solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol methyl ethyl ether, ethylene glycol diethyl ether, and diethylene glycol dimethyl ether;
Polyhydric alcohol partial alkyl ether acetate solvents such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate;
Aliphatic ether solvents such as diethyl ether, dipropyl ether, dibutyl ether, butyl methyl ether, butyl ethyl ether, diisoamyl ether, hexyl methyl ether, octyl methyl ether, cyclopentyl methyl ether, dicyclopentyl ether;
Aliphatic-aromatic ether solvents such as anisole and phenylethyl ether;
Examples include cyclic ether solvents such as tetrahydrofuran, tetrahydropyran, and dioxane. Of these, diisoamyl ether is preferred.

  Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-i-butyl ketone, methyl-n-pentyl ketone, ethyl-n-butyl ketone, methyl-n- Examples include hexyl ketone, di-i-butyl ketone, trimethylnonanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone, and acetophenone.

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

  Examples of ester solvents include diethyl carbonate, propylene carbonate, methyl acetate, ethyl acetate, γ-butyrolactone, γ-valerolactone, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, sec sec -Butyl, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methyl pentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methyl cyclohexyl acetate, n-nonyl acetate, acetoacetic acid Methyl, ethyl acetoacetate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol acetate Non-n-butyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, glycol diacetate Methoxytriglycol acetate, ethyl propionate, n-butyl propionate, i-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate, Examples include diethyl malonate, dimethyl phthalate, and diethyl phthalate.

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

  Of these, ether solvents and alcohol solvents are preferable, and ether solvents are more preferable, from the viewpoint that elution of resist film components hardly occurs. As the alcohol solvent, a monoalcohol solvent is preferable, an alcohol solvent having 4 to 8 carbon atoms is more preferable, an alcohol solvent having 5 or 6 carbon atoms is more preferable, and 4-methyl-2-pentanol is particularly preferable. . As the ether solvent, an aliphatic ether solvent is preferable, an aliphatic ether solvent having 6 to 12 carbon atoms is more preferable, an aliphatic ether solvent having 9 to 11 carbon atoms is further preferable, and diisoamyl ether is particularly preferable. . These solvents may be used alone or in combination of two or more.

<Optional component>
In addition to the [A] polymer component and the [B] solvent, the composition for forming a liquid immersion upper layer film may contain an optional component as long as the effects of the present invention are not impaired. Examples of the optional component include a surfactant that can improve the coating property of the composition for forming a liquid immersion upper layer film on a resist film.

<Method for Preparing Composition for Forming Liquid Immersion Upper Layer>
The composition for forming a liquid immersion upper layer film can be prepared, for example, by mixing the [A] polymer component and, if necessary, the optional component in the [B] solvent at a predetermined ratio. In addition, the composition for forming a liquid immersion upper layer film can be prepared and used in a state of being dissolved or dispersed in an appropriate [B] solvent.

<Resist pattern formation method>
The resist pattern forming method of the present invention comprises:
(1) forming a resist film on the substrate;
(2) A step of laminating an immersion upper film on the resist film using the composition for forming an immersion upper film;
(3) immersion exposure of the resist film on which the liquid immersion upper layer film is laminated by irradiation of radiation through a photomask; and (4) a step of developing the immersion exposed resist film. Each step will be described in detail below.

[(1) Process]
In this step, a resist film is formed on the substrate. This step is usually performed by applying a photoresist composition to the substrate. As the substrate, for example, a conventionally known substrate such as a silicon wafer or a wafer coated with aluminum can be used. Further, for example, an organic or inorganic lower antireflection film disclosed in Japanese Patent Publication No. 6-12452, Japanese Patent Application Laid-Open No. 59-93448, etc. may be formed on the substrate.

  Examples of the coating method include spin coating (spin coating), cast coating, and roll coating. In addition, as a film thickness of the resist film formed, it is 0.01 micrometer-1 micrometer normally, and 0.01 micrometer-0.5 micrometer are preferable.

  After apply | coating a photoresist composition, you may volatilize the solvent in a coating film by prebaking (PB) as needed. The heating conditions for PB are appropriately selected depending on the composition of the photoresist composition, but are usually about 30 ° C to 200 ° C, preferably 50 ° C to 150 ° C.

  In order to prevent the influence of basic impurities contained in the environmental atmosphere, a protective film disclosed in, for example, Japanese Patent Laid-Open No. 5-188598 can be provided on the resist layer. Furthermore, in order to prevent the acid generator and the like from flowing out of the resist layer, a liquid immersion protective film disclosed in, for example, Japanese Patent Application Laid-Open No. 2005-352384 can be provided on the resist layer. These techniques can be used in combination.

[Step (2)]
In this step, the liquid immersion upper layer film is laminated on the resist film formed in step (1) using the liquid immersion upper layer film forming composition. In this step, it is preferable to fire after applying the composition for forming a liquid immersion upper layer film. By laminating the immersion film on the resist film in this way, the immersion liquid and the resist film are not in direct contact with each other, so that the immersion liquid penetrates into the resist film, resulting in the lithography performance of the resist film. It is effectively prevented that the lens of the projection exposure apparatus is contaminated by a component that is reduced or is eluted from the resist film into the immersion liquid. As a method for laminating the liquid immersion upper layer film, a method similar to the method for forming the resist film can be adopted except that the liquid immersion upper layer film forming composition is used instead of the resist composition.

  The thickness of the immersion 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). By doing in this way, the reflection suppression effect in the upper interface of a resist film can be enlarged.

[Step (3)]
In this step, the resist film on which the liquid immersion upper layer film is laminated is subjected to liquid immersion exposure by irradiation with radiation through a photomask. In this immersion exposure, an immersion medium is disposed between the immersion upper layer film and the lens, and exposure light is applied to the resist film and the immersion upper layer film through the immersion medium and a mask having a predetermined pattern. This is done by irradiating.

  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. In a state where the immersion medium is interposed, that is, in a state where the immersion medium is filled between the lens of the exposure apparatus and the upper immersion film, a mask having a predetermined pattern is irradiated with radiation from the exposure apparatus. Then, the liquid immersion upper layer film and the photoresist film are exposed.

  The radiation used for this exposure (immersion exposure) can be appropriately selected according to the type of resist film or immersion upper layer film. For example, visible rays; ultraviolet rays such as g rays and i rays; Various radiations such as ultraviolet rays; X-rays such as synchrotron radiation; and charged particle beams such as electron beams can be used. Among these, an ArF excimer laser (wavelength 193 nm) and a KrF excimer laser (wavelength 248 nm) are preferable. The exposure light irradiation conditions, for example, the radiation dose, can be appropriately set according to the composition of the photoresist composition and / or the composition for forming an immersion upper layer film, the type of additive, and the like.

  In addition, post exposure baking (PEB) is preferably performed after exposure. By performing PEB, the dissociation reaction of the acid dissociable group in the photoresist composition can proceed smoothly. As a heating condition of PEB, it is 30 degreeC-200 degreeC normally, and 50 degreeC-170 degreeC is preferable.

[Step (4)]
This step is a step of developing the resist film subjected to immersion exposure in the step (3) to form a resist pattern. In the method of forming the resist pattern, the liquid immersion upper layer film is formed by the liquid immersion upper layer film forming composition. Therefore, with the developer during development, or with the cleaning liquid when cleaning after development, The liquid immersion upper layer film can be easily removed. That is, no separate peeling process is required to remove the liquid immersion upper layer film.

  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, dimethylethanolamine. , Triethanolamine, tetraalkylammonium hydroxide (TMAH), tetraalkylammonium hydroxides such as tetraethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene An alkaline aqueous solution in which at least one alkaline compound such as 1,5-diazabicyclo- [4.3.0] -5-nonane is dissolved is preferable. Among these, tetraalkylammonium hydroxide aqueous solutions are more preferable.

  An appropriate amount of a water-soluble organic solvent such as alcohols such as methanol and ethanol, and a surfactant can be added to the developer. In addition, when developing using alkaline aqueous solution, it is preferable to wash with water after image development, and you may dry after washing with water.

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

[Weight average molecular weight (Mw), number average molecular weight (Mn) and dispersity (Mw / Mn)]
Mw and Mn of the polymer were measured by gel permeation chromatography (GPC) using Tosoh GPC columns (2 G2000HXL, 1 G3000HXL, 1 G4000HXL) under the following conditions. The degree of dispersion (Mw / Mn) was calculated from the measurement results of Mw and Mn.
Eluent: Tetrahydrofuran Flow rate: 1.0 mL / min Sample concentration: 1.0% by mass
Sample injection volume: 100 μL
Column temperature: 40 ° C
Detector: Differential refractometer Standard material: Monodisperse polystyrene

[ ¹³ C-NMR analysis]
^{The 13} C-NMR analysis was performed using JEOL JNM-EX270 and using acetone-d ₆ as a measurement solvent. The content rate of each structural unit in a polymer was computed from the area ratio of the peak corresponding to each structural unit in the spectrum obtained by < ¹³ > C-NMR.

<[A] Synthesis of polymer component>
The monomer used for the synthesis | combination of a polymer (A1) and a polymer (A2) is shown below.

[Synthesis Example 1]
Compound (M-1) giving structural unit (I) 0.62 g (5 mol%), compound (M-5) giving structural unit (II) 6.90 g (35 mol%) and compound (M-8) A monomer solution prepared by dissolving 5.49 g (60 mol%) and 1.00 g of a polymerization initiator 2,2′-azobis- (methyl methyl 2-methylpropionate) in 40.00 g of methyl ethyl ketone was prepared for 30 minutes. Nitrogen purged. After purging with nitrogen, the inside of the flask was heated to 80 ° C. while stirring with a magnetic stirrer, and a monomer solution prepared in advance was added dropwise over 3 hours using a dropping funnel. After completion of dropping, the reaction was continued for another 3 hours. The polymerization liquid was obtained by cooling until it became 30 degrees C or less.
Subsequently, after concentrating the obtained copolymer liquid to 44 g, it moved to the separatory funnel. To this separatory funnel, 44 g of methanol and 220 g of n-hexane were added for separation and purification. After separation, the lower layer solution was recovered. The recovered lower layer solution and 220 g of n-hexane were added to carry out separation and purification. After separation, the lower layer solution was recovered. The recovered lower layer solution was replaced with 4-methyl-2-pentanol to obtain a solution containing the polymer component (A-1). The solid content concentration of the solution containing the polymer component (A-1) is calculated from the mass of the residue after 0.5 g of the polymer solution is placed on an aluminum dish and heated on a hot plate heated to 155 ° C. for 30 minutes. Then, the value of the solid content concentration was used for the subsequent preparation of the protective film-forming composition solution and the yield calculation. Mw of the obtained polymer (A-1) was 10,500, Mw / Mn was 1.53, and the yield was 80%. Moreover, as a result of the ¹³ C-NMR analysis, the content ratio of each structural unit derived from the compound (M-1), the compound (M-5) and the compound (M-8) was 5.0: 34.7: 60. .3 (mol%).

[Synthesis Examples 2 to 11]
Polymers (A-2) to (A-10) and (a-1) were obtained in the same manner as in Synthesis Example 1 except that a predetermined amount of the monomers listed in Table 1 were used. In addition, Table 2 shows the content of each structural unit, Mw, Mw / Mn ratio, and yield (%) of each polymer obtained. In Tables 1 and 2, “-” indicates that the corresponding monomer was not used.

<Synthesis of polymer (A2)>
[Synthesis Example 12]
60.57 g (85 mol%) of the compound (M-5) giving the structural unit (II) and 4.53 g of the polymerization initiator 2,2′-azobis- (methyl 2-methylpropionate) were added to 40.00 g of isopropanol. A dissolved monomer solution was prepared.
Meanwhile, 50 g of isopropanol was charged 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 a monomer solution prepared in advance was added dropwise over 2 hours using a dropping funnel. After completion of the dropping, the reaction was further continued for 1 hour, and 10 g of an isopropanol solution of 3.19 g (15 mol%) of the compound (M-11) giving the structural unit (III) was dropped over 30 minutes. Then, after reacting further for 1 hour, the polymerization liquid was obtained by cooling until it became 30 degrees C or less.
The obtained polymerization solution was concentrated to 150 g and 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 put into the above 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 substituted with 4-methyl-2-pentanol to obtain a solution containing the polymer (A2-1). Mw of the obtained polymer (A2-1) was 8,000, Mw / Mn was 1.51, and the yield was 80%. Moreover, the content rate of each structural unit derived from (M-5) and (M-11) was 98 mol% and 2 mol%, respectively.

[Synthesis Examples 13 to 17]
Polymers (A2-2) to (A2-6) were obtained in the same manner as in Synthesis Example 12 except that a predetermined amount of the monomers listed in Table 3 were used. In addition, Table 4 shows the content of each structural unit, Mw, Mw / Mn ratio, and yield (%) of each polymer obtained. In Tables 3 and 4, “-” indicates that the corresponding monomer was not used.

<Preparation of composition for forming liquid immersion upper layer film>
The [B] solvent used for the preparation of the composition for forming the liquid immersion upper layer film is shown below.
[[B] solvent]
(B-1): 4-Methyl-2-pentanol (B-2): Diisoamyl ether

[Example 1]
[A] 20 parts by mass of the polymer (A1-1) as the polymer component, 80 parts by mass of the polymer (A2-1), and (B-1) 1,000 parts by mass of (B-1) as the solvent and (B -2) After mixing 4,000 mass parts and stirring for 2 hours, the composition for liquid immersion upper film | membrane formation of Example 1 was obtained by filtering with a 0.2 micrometer pore diameter filter.

[Examples 2 to 14 and Comparative Example 1]
Each composition for forming an immersion upper layer film was obtained in the same manner as in Example 1 except that the components of the types and amounts described in Table 5 were mixed.

<Preparation of photoresist composition>
A photoresist composition for forming a resist film was prepared by the following method.

<Synthesis of polymer for photoresist composition>
[Synthesis Example 18]
The following compound (RM-1) 53.93 g (50 mol%), compound (RM-2) 35.38 g (40 mol%), compound (RM-3) 10.69 g (10 mol%) was added to 2-butanone 200 g And a monomer solution charged with 5.58 g of dimethyl 2,2′-azobis (2-methylpropionate) was prepared, and a 500 mL three-necked flask charged with 100 g of 2-butanone was charged with nitrogen for 30 minutes. Purged. 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 less, poured into 2,000 g of methanol, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice by slurry with 400 g of methanol, filtered, and dried at 50 ° C. for 17 hours to obtain a white powder polymer (P-1). (74 g, 74% yield). This polymer (P-1) had Mw of 6,900 and Mw / Mn = 1.70. As a result of ¹³ C-NMR analysis, the content ratio of each structural unit derived from the compound (RM-1), the compound (RM-2) and the compound (RM-3) was 53.0: 37.2: 9. 0.8 (mol%). 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.

<Preparation of photoresist composition>
[Synthesis Example 19]
100 parts by weight of polymer (P-1), 1.5 parts by weight of triphenylsulfonium nonafluoro-n-butanesulfonate as acid generator and 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium nona 6 parts by mass of fluoro-n-butanesulfonate and 0.65 parts by mass of R-(+)-(tert-butoxycarbonyl) -2-piperidinemethanol as an acid diffusion controller are mixed, and propylene glycol as a solvent is mixed with this mixture. By adding 2,900 parts by mass of monomethyl ether acetate, 1,250 parts by mass of cyclohexanone and 100 parts by mass of γ-butyrolactone, adjusting the total solid content concentration to 5% by mass and filtering with a filter having a pore size of 30 nm, a photoresist is obtained. A composition (α) was prepared.

<Evaluation>
A liquid immersion upper film was formed using each liquid immersion upper film forming composition obtained in the above Examples and Comparative Examples, and various evaluations shown below were performed. The evaluation results are shown in Table 5. Note that “-” in Table 5 indicates that the item was not evaluated.

[Solubility]
Each composition for forming a liquid immersion upper layer film was stirred for 30 minutes. Then, the case where it became cloudy visually was set to "B (defect)", and the case where it melt | dissolved without becoming cloudy was evaluated as "A (good)." In addition, about the thing whose solubility test became x, other evaluation was not performed.

[Solubility in developer]
Each liquid upper layer film forming composition is spin-coated on an 8-inch silicon wafer with CLEAN TRACK ACT8 (manufactured by Tokyo Electron), and PB is performed at 90 ° C. for 60 seconds to form a liquid immersion upper layer film with a film thickness of 90 nm. did. The film thickness was measured using Lambda Ace VM90 (Dainippon Screen). The liquid immersion upper layer film was subjected to paddle development for 60 seconds using a 2.38 mass% TMAH aqueous solution, spin-dried by shaking, and the wafer surface was observed. At this time, if there was no residue and the film was developed, the dissolution performance in the developer was “A (good)”, and if the residue was observed, it was “B (bad)”.

[Backward contact angle (°)]
Each composition for forming a liquid immersion upper layer film was spin-coated on an 8-inch silicon wafer, and PB was performed at 90 ° C. for 60 seconds on a hot plate to form a liquid immersion upper film having a thickness of 30 nm. Thereafter, using DSA-10 (manufactured by KRUS), the receding contact angle was quickly measured in an environment of 23 ° C., humidity 45%, and normal pressure. That is, the wafer stage position of DSA-10 was adjusted, and the wafer was set on the adjusted stage. Next, water was injected into the needle, and the position of the needle was finely adjusted to an initial position where water droplets can be formed on the set wafer. Thereafter, water was discharged from the needle to form a 25 μL water droplet on the wafer. The needle was once withdrawn from the water droplet, and the needle was pulled down to the initial position again and placed in the water droplet. Subsequently, a water droplet was sucked with a needle at a speed of 10 μL / min for 90 seconds, and at the same time, the contact angle was measured once every second, for a total of 90 times. Of these, the average value for the contact angle for 20 seconds from the time when the measured value of the contact angle was stabilized was calculated as the receding contact angle (°). The closer the receding contact angle is to 90 °, the higher the water repellency of the liquid immersion upper layer film.

[Evaluation of dissolution amount of photoresist composition]
Silicon with a central portion hollowed out into a circular shape with a diameter of 11.3 cm at the center on an 8-inch silicon wafer subjected to HMDS (hexamethyldisilazane) treatment at 100 ° C. for 60 seconds using the CLEAN TRACK ACT8. A rubber sheet (made by Kureha Elastomer, thickness: 1.0 mm, shape: square with a side of 30 cm) was placed. Next, 10 mL of ultrapure water was filled in the hollowed out portion at the center of the silicon rubber using a 10 mL hole pipette.
On the other hand, a lower antireflection film composition (ARC29A, manufactured by Brewer Science) was applied in advance so as to form a lower antireflection film having a film thickness of 77 nm using the CLEAN TRACK ACT8. Next, a photoresist composition (α) was spin-coated on the lower antireflection film, and PB was performed at 115 ° C. for 60 seconds to form a resist film having a thickness of 205 nm. Thereafter, each liquid immersion upper film forming composition was applied onto the resist film to form a liquid immersion upper film. The liquid immersion upper layer side was stacked so as to come into contact with the ultrapure water in the silicon rubber sheet of the prepared wafer, and kept in that state for 10 seconds. Thereafter, ultrapure water was collected with a glass syringe and used as a sample for analysis. Note that the recovery rate of ultrapure water after the experiment was 95% or more.
The peak intensity of the anion part of the photoacid generator in ultrapure water is described below using LC-MS (liquid chromatograph mass spectrometer, LC part: SERIES1100 manufactured by AGILENT, MS part: Mariner manufactured by Perseptive Biosystems, Inc.). The measurement conditions were as follows. At that time, the peak intensity of the 1 ppb, 10 ppb, and 100 ppb aqueous solutions of the photoacid generator was measured under the following measurement conditions to prepare a calibration curve, and the elution amount was calculated from the peak intensity using this calibration curve. Similarly, each peak intensity of the 1 ppb, 10 ppb, and 100 ppb aqueous solutions of the acid diffusion control agent is measured under the following measurement conditions to create a calibration curve, and the calibration curve is used to calculate the acid diffusion control agent from the peak intensity. The amount of elution was calculated. When the elution amount is 5.0 × 10 ⁻¹² mol / cm ² or less, the elution suppression performance of the photoresist composition is “A (good)”, 5.0 × 10 ⁻¹² mol / cm ^2. If it was larger than "B (defect)".

(Measurement condition)
Column used: “CAPCELL PAK MG”, manufactured by Shiseido, 1 flow rate: 0.2 mL / min Eluent: water / methanol (3/7) with 0.1% by weight of formic acid Measurement temperature: 35 ° C.

[Blob defect]
A 12-inch silicon wafer surface was spin-coated with a lower antireflection film (ARC66, manufactured by Nissan Chemical Co., Ltd.) using Lithius Pro-i (manufactured by Tokyo Electron), and then subjected to PB (205 ° C., 60 seconds) to form a film. A lower antireflection film having a thickness of 105 nm was formed. Next, a photoresist composition (α) was spin-coated using CLEAN TRACK ACT12, PB was performed at 100 ° C. for 60 seconds, and cooled at 23 ° C. for 30 seconds to form a resist film having a thickness of 100 nm. Thereafter, each liquid immersion upper film forming composition was applied onto the resist film to form a liquid immersion upper film.
Next, using an ArF immersion exposure apparatus (S610C, manufactured by NIKON), exposure was performed through a mask for projecting a pattern of 45 nm line / 90 nm pitch under the optical conditions of NA: 1.30 and Crosspore ( Hereinafter, the dimension of the pattern projected by the mask is referred to as the “pattern dimension.” For example, a mask having a pattern dimension of 40 nm line / 84 nm pitch is a mask for projecting a pattern of 40 nm line / 84 nm pitch. ). After PEB was performed on the above-mentioned Lithius Pro-i hot plate at 100 ° C. for 60 seconds and cooled at 23 ° C. for 30 seconds, a 2.38 wt% TMAH aqueous solution was used as a developer at the GP nozzle of the developing cup. Paddle development was performed for 10 seconds and rinsed with ultrapure water. An evaluation substrate on which a resist pattern was formed was obtained by spin-drying at 2,000 rpm for 15 seconds. At this time, the exposure amount at which a resist pattern having a 45 nm line / 90 nm pitch was formed in a mask having a pattern dimension of 45 nm line / 90 nm pitch was determined as the optimum exposure amount. When a resist pattern with a 45 nm / 90 nm pitch was formed, the case where the number of blob defects in the unexposed area was 200 or less was evaluated as “A (good)”, and the case where it exceeded 200 was evaluated as “B (defective)”. .

[Bridge defect]
A 12-inch silicon wafer surface was spin-coated with a lower antireflection film (ARC66, manufactured by Nissan Chemical Co., Ltd.) using Lithius Pro-i (manufactured by Tokyo Electron), and then subjected to PB (205 ° C., 60 seconds) to form a film. A lower antireflection film having a thickness of 105 nm was formed. Next, the photoresist composition (α) was spin-coated using the CLEAN TRACK ACT12, PB was performed at 100 ° C. for 60 seconds, and cooled at 23 ° C. for 30 seconds to form a resist film having a thickness of 100 nm. . Thereafter, each liquid immersion upper film forming composition was applied onto the resist film to form a liquid immersion upper film.
Next, using an ArF immersion exposure apparatus (S610C, manufactured by NIKON), exposure was performed through a mask for projecting a pattern of 45 nm line / 90 nm pitch under the optical conditions of NA: 1.30 and Crosspore ( Hereinafter, the dimension of the pattern projected by the mask is referred to as the “pattern dimension.” For example, a mask having a pattern dimension of 40 nm line / 84 nm pitch is a mask for projecting a pattern of 40 nm line / 84 nm pitch. ). After PEB was performed on the above-mentioned Lithius Pro-i hot plate at 100 ° C. for 60 seconds and cooled at 23 ° C. for 30 seconds, a 2.38 wt% TMAH aqueous solution was used as a developer at the GP nozzle of the developing cup. Paddle development was performed for 10 seconds and rinsed with ultrapure water. An evaluation substrate on which a resist pattern was formed was obtained by spin-drying at 2,000 rpm for 15 seconds. At this time, the exposure amount at which a resist pattern having a 45 nm line / 90 nm pitch was formed in a mask having a pattern dimension of 45 nm line / 90 nm pitch was determined as the optimum exposure amount. When a resist pattern having a 45 nm / 90 nm pitch was formed, the case where no bridge defect was found was designated as “A (good)”, and the case where it was seen was designated as “B (defective)”.

[Peeling resistance]
As the substrate, an 8-inch silicon wafer not subjected to HMDS treatment was used. Each liquid immersion upper layer resin composition was spin-coated on the substrate with the CLEAN TRACK ACT8, and then PB was performed at 90 ° C. for 60 seconds to obtain a liquid immersion upper layer film having a thickness of 30 nm. Thereafter, rinsing with pure water was performed for 60 seconds in the CLEAN TRACK ACT8, followed by drying by shaking off. The case where peeling is observed in the center after rinsing by visual inspection is “C (defect)”, the case where peeling is observed only at the edge is “B (slightly good)”, and the case where peeling is not observed is “A ( It was evaluated as “good”.

[Pattern shape]
This evaluation was performed to evaluate whether or not a high-resolution resist pattern was formed. First, by using the above-mentioned Lithius Pro-i on a 12-inch silicon wafer, spin coating the composition for the lower antireflection film (ARC66, manufactured by Nissan Chemical Industries) and performing PB (205 ° C., 60 seconds) A lower antireflection film having a thickness of 105 nm was formed. A photoresist composition (α) was spin-coated on the formed lower antireflection film, and PB (100 ° C., 60 seconds) was performed to form a resist film having a thickness of 100 nm.
On the formed resist film, each liquid immersion upper layer film-forming composition was spin coated, and PB (90 ° C., 60 seconds) was performed to form a liquid immersion upper layer film having a thickness of 30 nm. Using an ArF immersion exposure apparatus (S610C, manufactured by NIKON), exposure was performed through a mask for projecting a pattern of 45 nm line / 90 nm pitch. After PEB was performed on the above-mentioned Lithius Pro-i hot plate at 100 ° C. for 60 seconds and cooled at 23 ° C. for 30 seconds, a 2.38 wt% TMAH aqueous solution was used as a developer at the GP nozzle of the developing cup. Paddle development was performed for 10 seconds and rinsed with ultrapure water. An evaluation substrate on which a resist pattern was formed was obtained by spin-drying at 2,000 rpm for 15 seconds.
With respect to the formed resist pattern, the exposure amount for forming a line-and-space pattern (1L1S) having a line width of 90 nm in a one-to-one line width was determined as the optimum exposure amount. Note that a scanning electron microscope (CG-4000, manufactured by Hitachi Instruments) was used for the measurement. In addition, the cross-sectional shape of the line-and-space pattern with a line width of 90 nm was observed with a scanning electron microscope (S-4800, manufactured by Hitachi Keiki Co., Ltd.). The line width Lb in the middle in the height direction of the pattern formed on the substrate and the line width La in the upper part of the pattern are measured, and when 0.9 ≦ La / Lb ≦ 1.1, the case of “A ( The case where “good”, La / Lb <0.9, or La / Lb> 1.1 was evaluated as “B (defect)”.

  As shown in Table 5, according to the compositions for forming a liquid immersion upper layer film of Examples 1 to 14, a liquid immersion upper film sufficiently satisfying basic characteristics such as water repellency, solubility in a developer, and peeling resistance is formed. I was able to. Moreover, according to the composition for liquid immersion upper layer film formation of Examples 1-14, the bridge | bridging defect and the blob defect were suppressed in resist pattern formation, and the pattern shape was also excellent.

  According to the composition for forming a liquid immersion upper layer film of the present invention, a liquid immersion upper film sufficiently satisfying basic characteristics such as water repellency and solubility in a developer can be formed, and bridge defects and blobs in resist pattern formation can be formed. Development defects such as defects can be suppressed, and a resist pattern having an excellent pattern shape can be formed. Therefore, they can be suitably used for lithography processes in the manufacture of electronic devices that will be increasingly miniaturized in the future.

Claims (8)

[A] a polymer component containing a polymer (A1), and [B] a solvent,
The composition for liquid immersion upper film formation in which a polymer (A1) has the structural unit (I) containing group represented by following formula (1).

(In Formula (1), R ¹ is an alkali dissociable group. R ² is an (n + 1) -valent linking group. A is —CO—O— *, —SO ₂ —O— *, An oxygen atom or —NR ³ —, R ³ is a hydrogen atom or an alkali-dissociable group, * represents a site bonded to R ¹ , provided that when A is an oxygen atom, A in R ² There is no case where the site directly connected to carbonyl group or sulfonyl group, n is an integer of 1 to 3. However, when n is 2 or more, a plurality of R ¹ and A are the same or different. May be.) The composition for forming a liquid immersion upper layer film according to claim 1, wherein the structural unit (I) is represented by the following formula (2).

(In Formula (2), R ⁵ is a hydrogen atom, a methyl group, a hydroxymethyl group, or a trifluoromethyl group. R ⁴ is —CO—O—, —O—CO—O—, —O—, -SO ₂ -, - CO-NH- or _-SO 2 NH- .n, ^{R 1} and ^{R 2} is as defined in the above formula (1)). The alkali dissociable group of R ¹ is a monovalent hydrocarbon group having 1 to 20 carbon atoms, a group represented by the following formula (3), or a group represented by the following formula (4): Or the composition for liquid immersion upper film formation of Claim 2.

(In the formula (3), R ^{6 to} R ⁹ are a hydrogen atom, a fluorine atom or a perfluoroalkyl group, provided that at least one of R ^{6 to} R ⁹ is a fluorine atom or a perfluoroalkyl group. R ¹⁰ is a hydrogen atom, a fluorine atom or a monovalent organic group.
In the formula (4), a is 0 or 1. b is an integer of 0-5. R ¹¹ is a fluorine atom or a monovalent organic group that may contain a fluorine atom. However, when b is 2 or more, the plurality of R ¹¹ may be the same or different. )   [A] The content ratio of the structural unit (I) in the polymer component is 0.1 mol% or more and 50 mol% or less with respect to all the structural units constituting the [A] polymer component. The composition for forming a liquid immersion upper layer film according to claim 2.   [A] The polymer component contains at least one group selected from the group consisting of a fluorinated alkyl group and a fluorinated hydroxyalkyl group in the same or different polymer as the polymer (A1), and the above formula The composition for forming a liquid immersion upper layer film according to claim 1 or 2, further comprising a structural unit (II) not containing the group represented by (1). [A] The polymer component is at least one group selected from the group consisting of a carboxy group, a sulfo group and a group represented by the following formula (11) in the same or different polymer as the polymer (A1). The composition for forming a liquid immersion upper layer film according to claim 1, further comprising a structural unit (III) containing

(In the formula (11), R ²³ is a hydrogen atom, a halogen atom, a nitro group, an alkyl group, a monovalent alicyclic hydrocarbon group, an alkoxy group, an acyl group, an aralkyl group or an aryl group. The above alkyl group A part or all of hydrogen atoms of the alicyclic hydrocarbon group, alkoxy group, acyl group, aralkyl group and aryl group may be substituted, R ²⁴ is —C (═O) —R ²⁵ , ^{_{-S (= O) 2 -R 26}} , -R 27 .R 25 and ^{R 26} is -CN or ^-R 28 -NO ₂ are each independently a hydrogen atom, an alkyl group, fluorinated alkyl group, 1 A valent alicyclic hydrocarbon group, an alkoxy group, a cyano group, a cyanomethyl group, an aralkyl group or an aryl group, provided that R ²⁵ or R ²⁶ and R ²³ are bonded to each other to form a ring structure. Good, R ²⁷ and R ²⁸ is each independently a single bond, a methylene group or an alkylene group having 2 to 5 carbon atoms.)   [B] The composition for forming a liquid immersion upper layer film according to claim 1 or 2, wherein the solvent comprises an ether solvent. (1) forming a resist film on the substrate;
(2) A step of laminating an immersion upper film on the resist film using the composition for forming an immersion upper film according to claim 1 or 2,
(3) a resist pattern including a step of immersion exposure of the resist film on which the liquid immersion upper layer film is laminated by irradiation of radiation through a photomask; and (4) a step of developing the liquid immersion exposed resist film. Forming method.