JP5724794B2 - Composition for forming immersion upper layer film - Google Patents

Description

  The present invention relates to a composition for forming a liquid immersion upper layer film.

  In the manufacture of semiconductor devices, fine processing by lithography using a chemically amplified resist composition has been conventionally performed. The pattern forming method used in this microfabrication generally includes a step of forming a resist film on a substrate, an exposure step of irradiating the resist film with radiation such as ultraviolet rays through a mask, and developing the exposed resist film. A developing step, and a step of etching the substrate using the obtained resist pattern as a protective film.

  In this pattern formation method, the acid-dissociable group of the polymer in the resist composition is eliminated by the acid generated in the exposed portion, and the polarity is changed so that the dissolution rate in the developer is different between the exposed portion and the unexposed portion. Pattern formation.

  In recent years, as a method for forming a finer resist pattern, there has been a 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. It is expanding. According to this immersion exposure method, it is possible to increase the numerical aperture (NA) of the lens, and even when the NA is increased, there is an advantage that the depth of focus is not easily lowered and high resolution can be obtained. is there.

  In this pattern formation method by the immersion exposure method, it is required to suppress elution of the resist film component into the immersion medium, and to suppress pattern defects caused by droplets of the immersion medium remaining on the resist film surface. As a technique for satisfying these requirements, it has been proposed to provide a protective film (immersion upper layer film) between a resist film and an immersion medium (Japanese Patent Laid-Open No. 2006-91798, International Publication No. 2008/2008). 47678 and International Publication No. 2009/41270). In these publications, a liquid immersion upper layer film is formed on a resist film using a water-insoluble and alkali-soluble polymer, and at the time of exposure, elution of resist film components and blobs are caused by the water repellency of the liquid immersion upper layer film. It is disclosed to remove the liquid immersion upper layer film from the resist film surface by suppressing pattern defects such as defects and bridge defects and dissolving the liquid immersion upper layer film in a developing solution in the subsequent development process. .

  However, when the water repellency of the liquid immersion upper layer film is increased, the amount of the resist film component eluted into the liquid immersion upper layer film, the Blob defect and the bridge defect are reduced and improved, but the liquid immersion upper layer at the periphery of the liquid immersion upper film is improved. At the site where the film and the substrate are in direct contact, the resistance to peeling from the substrate tends to decrease due to the decrease in the adhesion between the liquid immersion upper layer film and the substrate. In addition, the solution stability as the composition, the solubility of the immersion upper layer film in the developer, and the pattern shape characteristics of the resist pattern to be formed must be satisfied, and these required characteristics must be satisfied in a well-balanced manner. Development of a composition for forming a liquid immersion upper layer film capable of forming a liquid immersion upper film capable of being developed is desired.

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

  The present invention has been made based on the circumstances as described above, and its purpose is to maintain the required characteristics of water repellency, elution amount, blob defect, bridge defect, solution stability, solubility, and pattern shape. However, an object of the present invention is to provide a composition for forming a liquid immersion upper film capable of forming a liquid immersion upper film capable of increasing the resistance to peeling from a substrate and satisfying these required characteristics in a well-balanced manner.

（式（１）中、Ｒ^１は、水素原子、ハロゲン原子、ニトロ基、アルキル基、脂環式炭化水素基、アルコキシ基、アシル基、アラルキル基又はアリール基である。但し、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^２は、−Ｃ（＝Ｏ）−Ｒ^３、−Ｓ（＝Ｏ）_２−Ｒ^４、−Ｒ^５−ＣＮ又は−Ｒ^６−ＮＯ_２である。上記Ｒ^３及びＲ^４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、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、上記Ｒ^３又はＲ^４とＲ^１とが互いに結合して、Ｒ^２及びＲ^１が結合している炭素原子と共に環構造を形成してもよい。上記Ｒ^５及びＲ^６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。Ｒ^７は、１価の有機基である。但し、上記Ｒ^７とＲ^１とが互いに結合して、Ｒ^７が結合している炭素原子及びＲ^１が結合している炭素原子と共に環構造を形成してもよい。） The invention made to solve the above problems is
[A] A compound represented by the following formula (1) having a molecular weight of 100 or more and 1,000 or less (hereinafter also referred to as “[A] compound”), [B] a weight having a structural unit (I) containing a fluorine atom. It is a composition for forming a liquid immersion upper layer film containing a polymer component (hereinafter also referred to as “[B] polymer component”) containing the coalescence (a), and a [C] solvent.

(In the formula (1), R ¹ is a hydrogen atom, a halogen atom, a nitro group, an alkyl group, an alicyclic hydrocarbon group, an alkoxy group, an acyl group, an aralkyl group or an aryl group, provided that the alkyl group, Some or all of the hydrogen atoms of the alicyclic hydrocarbon group, alkoxy group, acyl group, aralkyl group and aryl group may be substituted, and R ² represents —C (═O) —R ³ , —S (═O) ₂ —R ⁴ , —R ⁵ —CN or —R ⁶ —NO _{2. The} above R ³ and R ⁴ are each independently a hydrogen atom, an alkyl group, a fluorinated alkyl group, An alicyclic hydrocarbon group, an alkoxy group, a cyano group, a cyanomethyl group, an aralkyl group or an aryl group, provided that R ³ or R ⁴ and R ¹ are bonded to each other, and R ² and R ¹ are bonded to each other. Form a ring structure with the carbon atoms Or. The ^{R 5} and ^{R 6} may each independently represent a single bond, a methylene group or an alkylene group having 2 to 5 carbon atoms .R ⁷ is a monovalent organic group. However, the ^{R 7} And R ¹ may be bonded to each other to form a ring structure together with the carbon atom to which R ⁷ is bonded and the carbon atom to which R ¹ is bonded.)

  Thus, the liquid immersion upper film forming composition contains the [A] compound in addition to the [B] polymer component and the [C] solvent, thereby forming the liquid immersion upper film from the substrate. It is possible to form a liquid immersion upper layer film that enhances peeling resistance and can satisfy the above required characteristics in a well-balanced manner.

R ¹ in the above formula (1) is a hydrogen atom, a nitro group, an alkyl group, an alicyclic hydrocarbon group, an alkoxy group or an acyl group, and the above R ² is -C (= O) -R ³ ,- S (═O) ₂ —R ⁴ or —R ⁵ —CN is preferred. Thus, R ¹ and R ² within the above specified groups, can be met with higher balance the required properties.

（式（２）中、Ｒ^８は、１価の炭化水素基である。但し、上記Ｒ^８とＲ^１とが互いに結合して、Ｒ^７が結合している炭素原子及びＲ^１が結合している炭素原子と共に環構造を形成してもよい。） The organic group of R ⁷ in the above formula (1) is preferably represented by the following formula (2).

(In the formula (2), R ⁸ is a monovalent hydrocarbon group, provided that R ⁸ and R ¹ are bonded to each other, and the carbon atom to which R ⁷ is bonded and R ¹ are bonded. A ring structure may be formed together with the carbon atom.)

Thus, R ⁷ can satisfy the above required characteristics in a more balanced manner by being the specific group.

  In the composition for forming a liquid immersion upper layer film, the content of the [A] compound is preferably 0.1 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the [B] polymer component. Thus, the said required characteristic can be satisfy | filled with a sufficient balance effectively by making content of the [A] compound in the said composition for liquid immersion upper film formation into the said specific range.

（式（３−１）中、Ｒ^９及びＲ^１０は、水素原子、炭素数１〜４のアルキル基又は炭素数１〜４のフッ素化アルキル基である。但し、上記Ｒ^９及びＲ^１０のうち、少なくともいずれかは、炭素数１〜４のフッ素化アルキル基である。
式（３−２）中、Ｒ^１１は、炭素数１〜１０のフッ素化アルキル基又は炭素数３〜１０のフッ素化シクロアルキル基である。） The structural unit (I) is at least one selected from the group consisting of a structural unit containing a group represented by the following formula (3-1) and a structural unit containing a group represented by the following formula (3-2). The structural unit is preferably.

(In Formula (3-1), R ⁹ and R ¹⁰ are a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a fluorinated alkyl group having 1 to 4 carbon atoms, provided that R ⁹ and R ¹⁰ are Among these, at least one is a C1-C4 fluorinated alkyl group.
In formula (3-2), R ¹¹ represents a fluorinated alkyl group having 1 to 10 carbon atoms or a fluorinated cycloalkyl group having 3 to 10 carbon atoms. )

  As described above, when the structural unit (I) is a structural unit containing the specific group, the water repellency of the liquid immersion upper film formed from the liquid immersion upper film forming composition is further increased, and the amount of elution is increased. , The required characteristics for the Blob defect and the bridge defect can be made better.

  [B] The polymer component preferably further has a structural unit (II) containing a sulfo group in the same or different polymer as the polymer (a). Thus, the [B] polymer component further includes the structural unit (II) containing a sulfo group in the same or different polymer as the polymer (a), thereby reducing the film thickness of the resist film by the developer. As a result, it is possible to suppress defects in the resist pattern due to adhesion of development residues and the like.

  [C] The solvent preferably contains an ether solvent. Thus, when the [C] solvent contains an ether solvent, elution of the resist film component to the liquid immersion upper film at the time of liquid immersion upper film formation can be suppressed, and intermixing can be reduced.

  According to the composition for forming a liquid immersion upper layer film of the present invention, while maintaining the required properties of water repellency, elution amount, blob defect, bridge defect, solution stability, solubility and pattern shape, resistance to peeling from the substrate And a liquid immersion upper film that can satisfy these required characteristics in a well-balanced manner can be formed. Therefore, the composition for forming a liquid immersion upper layer film can be suitably applied to a semiconductor device manufacturing process in which further miniaturization of a resist pattern proceeds.

<Composition for forming liquid immersion upper layer film>
The composition for forming an immersion upper layer film of the present invention contains a [A] compound, a [B] polymer component, and a [C] solvent. Moreover, the said composition for liquid immersion upper film formation may contain arbitrary components in the range which does not impair the effect of this invention. Hereinafter, each component will be described in detail.

<[A] Compound>
The compound [A] is a compound having a molecular weight of 100 or more and 1,000 or less represented by the above formula (1). When the composition for forming a liquid immersion upper film contains the [A] compound having a methylene structure or a methine structure, the adhesion between the liquid immersion upper film and the substrate is enhanced. As a result, it is possible to increase the resistance to peeling of the liquid immersion upper layer film from the substrate. Moreover, it is excellent also in various characteristics about water repellency, elution amount, Blob defect, bridge defect, solution stability, solubility, and pattern shape. In addition, such a structure is presumed to have a lower influence of deprotection or the like on the resin in the resist film than carboxylic acid, sulfonic acid and the like, so that the lithography performance is also improved.

In the above formula (1), R ¹ is a hydrogen atom, a halogen atom, a nitro group, an alkyl group, an alicyclic hydrocarbon group, an alkoxy group, an acyl group, an aralkyl group or an aryl group. However, part 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 ² is —C (═O) —R ³ , —S (═O) ₂ —R ⁴ , —R ⁵ —CN or —R ⁶ —NO ₂ . R ³ and R ⁴ are each independently a hydrogen atom, an alkyl group, a fluorinated alkyl group, an alicyclic hydrocarbon group, an alkoxy group, a cyano group, a cyanomethyl group, an aralkyl group, or an aryl group. However, R ³ or R ⁴ and R ¹ may be bonded to each other to form a ring structure together with the carbon atom to which R ² and R ¹ are bonded. R ⁵ and R ⁶ are each independently a single bond, a methylene group or an alkylene group having 2 to 5 carbon atoms. R ⁷ is a monovalent organic group. However, R ⁷ and R ¹ may be bonded to each other to form a ring structure together with the carbon atom to which R ⁷ is bonded and the carbon atom to which R ¹ is bonded.

Examples of the halogen atom represented by R ¹ include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

The alkyl group represented by R ¹ is preferably an alkyl group having 1 to 20 carbon atoms, for example, a linear alkyl group such as a methyl group, an ethyl group, an n-propyl group, or an n-butyl group; Examples thereof include branched alkyl groups such as -propyl group, i-butyl group, sec-butyl group and t-butyl group.

The alicyclic hydrocarbon group represented by R ¹ is preferably an alicyclic hydrocarbon group having 3 to 20 carbon atoms, for example, a monocyclic alicyclic hydrocarbon group such as a cyclopentyl group or a cyclohexyl group; Examples thereof include polycyclic alicyclic hydrocarbon groups such as an adamantyl group, norbornyl group, and tetracyclodecanyl group. In the present specification, the alicyclic hydrocarbon group does not need to be composed only of the alicyclic hydrocarbon structure, and a part thereof may include a chain structure.

The alkoxy group represented by R ¹ is preferably an alkoxy group having 1 to 20 carbon atoms, and examples thereof include a methoxy group and an ethoxy group.

The acyl group represented by R ¹ is preferably an acyl group having 2 to 20 carbon atoms, and examples thereof include an acetyl group and a propionyl group.

The aralkyl group represented by R ¹ is preferably an aralkyl group having 7 to 12 carbon atoms, and examples thereof include a benzyl group, a phenethyl group, and a naphthylmethyl group.

The aryl group represented by R ¹ is preferably an aryl group having 6 to 10 carbon atoms, and examples thereof include a phenyl group, a tolyl group, a dimethylphenyl group, a 2,4,6-trimethylphenyl group, and a naphthyl group. It is done.

Examples of the group that may substitute the hydrogen atom of the alkyl group, monovalent alicyclic hydrocarbon group, alkoxy group, acyl group, aralkyl group and aryl group represented by R ¹ include a fluorine atom, A halogen atom such as a chlorine atom, a hydroxyl group, a nitro group, a cyano group and the like can be mentioned.

Examples of the alkyl group, alicyclic hydrocarbon group, alkoxy group, aralkyl group, and aryl group represented by R ³ and R ⁴ are the same as the examples of R ¹ . Examples of the fluorinated alkyl group represented by R ³ and R ⁴ include groups in which at least one of the hydrogen atoms exemplified as the alkyl group for R ¹ is substituted with a fluorine atom.

Examples of the alkylene group having 2 to 5 carbon atoms represented by R ⁵ and R ⁶ include an ethylene group, a propylene group, and a butylene group.

The monovalent organic group represented by R ⁷ is not particularly limited as long as it is a monovalent organic group, but is preferably a group represented by the above formula (2). When R ⁷ is a group represented by the above formula (2), the required characteristics can be satisfied in a more balanced manner.

In the above formula (2), R ⁸ is a monovalent hydrocarbon group. However, R ⁸ and R ¹ may be bonded to each other to form a ring structure together with the carbon atom to which R ⁷ is bonded and the carbon atom to which R ¹ is bonded.

Examples of the monovalent hydrocarbon group represented by R ⁸ include a linear or branched alkyl group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, Alternatively, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms can be used.

  Examples of the linear or branched alkyl group having 1 to 20 carbon atoms include, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, and sec-butyl group. , T-butyl group and the like.

Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclodecyl group, methylcyclohexyl group, and ethyl. Monocyclic saturated hydrocarbon group such as cyclohexyl group; cyclobutenyl group, cyclopentenyl group, cyclohexenyl group, cycloheptenyl group, cyclooctenyl group, cyclodecenyl group, cyclopentadienyl group, cyclohexadienyl group, cyclooctadienyl group, cyclo Monocyclic unsaturated hydrocarbon group such as decadiene; bicyclo [2.2.1] heptyl group, bicyclo [2.2.2] octyl group, tricyclo [5.2.1.0 ^2,6 ] decyl group , Tricyclo [3.3.1.1 ^3,7 ] decyl group, tetracyclo [6.2. 1.1 ^{3, 6} . 0 ^2,7 ] dodecyl group, polycyclic saturated hydrocarbon group such as adamantyl group and the like.

  Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include a phenyl group, a biphenyl group, a terphenyl group, a benzyl group, and a naphthyl group.

R ¹ is a hydrogen atom, nitro group, alkyl group, alicyclic hydrocarbon group, alkoxy group or acyl group, and R ² is —C (═O) —R ³ , —S (═O). ₂ -R is preferably ⁴ or ^-R 5 -CN. By using R ¹ and R ² as the specific group, the required characteristics can be satisfied in a more balanced manner.

  As the compound [A], a compound represented by the following formula is preferable.

  [A] The molecular weight of the compound is from 100 to 1,000, preferably from 100 to 500. When the molecular weight is within the specific range, the solubility in a [C] solvent described later is excellent.

  The compound [A] preferably has a boiling point of 200 ° C. or higher at 1 atmosphere. The compound [A] preferably has a melting point of 20 ° C. or higher.

  [A] The content of the compound is preferably 0.1 parts by mass or more and 100 parts by mass or less, and more preferably 0.5 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the polymer component [B]. [A] By making content of a compound into the said specific range, the said required characteristic can be satisfy | filled with sufficient balance effectively.

<[A] Compound Synthesis Method>
The compound [A] can be synthesized using a known method. Moreover, you may use a commercial item.

<[B] Polymer component>
[B] The polymer component includes a polymer (a) having a structural unit (I) containing a fluorine atom. [B] The polymer component may contain a polymer other than the polymer (a) (hereinafter also referred to as “other polymer”) within a range not impairing the effects of the present invention. In addition, the [B] polymer component may contain 2 or more types of each said polymer.

<Polymer (a)>
The polymer (a) has a structural unit (I) containing a fluorine atom. Moreover, it is preferable that a polymer (a) has structural unit (II) containing a sulfo group. Furthermore, the polymer (a) may have other structural units such as the structural unit (III). The polymer (a) may have two or more of each of the above structural units. Note that the structural units (II) and (III) may be included in the polymer (a) other polymer, or both the polymer (a) and the other polymer may be included. Good. Hereinafter, each structural unit will be described in detail.

[Structural unit (I)]
The structural unit (I) is a structural unit containing a fluorine atom. The structural unit (I) is not particularly limited as long as it is a structural unit containing a fluorine atom, but is represented by the structural unit containing a group represented by the formula (3-1) and the formula (3-2). It is preferably at least one structural unit selected from the group consisting of structural units containing groups. When the polymer (a) has the structural unit (I), the water repellency of the liquid immersion upper film formed from the liquid immersion upper film forming composition is increased, and the amount of elution, Blob defect and bridge defect are increased. The required characteristics can be improved.

In the above formula (3-1), ^{R 9} and ^{R 10} are hydrogen atom, a fluorinated alkyl group of 1 to 4 alkyl groups or carbon atoms having 1 to 4 carbon atoms. However, at least one of R ⁹ and R ¹⁰ is a fluorinated alkyl group having 1 to 4 carbon atoms. In said formula (3-2), R < ¹¹ > is a C1-C10 fluorinated alkyl group or a C3-C10 fluorinated cycloalkyl group. )

Examples of the alkyl group having 1 to 4 carbon atoms represented by R ⁹ and R ¹⁰ include linear alkyl groups such as methyl group, ethyl group, n-propyl group, and n-butyl group; i-propyl group , Branched alkyl groups such as i-butyl group, sec-butyl group and t-butyl group.

  The fluorinated alkyl group having 1 to 4 carbon atoms is a group in which at least one hydrogen atom of the alkyl group having 1 to 4 carbon atoms is substituted with a fluorine atom. As the alkyl group having 1 to 4 carbon atoms, the same groups as those exemplified as the alkyl group having 1 to 4 carbon atoms can be used.

The fluorinated alkyl group having 1 to 10 carbon atoms represented by R ¹¹ is a group in which at least one hydrogen atom of the alkyl group having 1 to 10 carbon atoms is substituted with a fluorine atom. Examples of the alkyl group having 1 to 10 carbon atoms include linear alkyl groups such as methyl group, ethyl group, n-propyl group, and n-butyl group; i-propyl group, i-butyl group, sec- Examples thereof include branched alkyl groups such as a butyl group and a t-butyl group.

The fluorinated cycloalkyl group having 3 to 10 carbon atoms represented by R ¹¹ is a group in which at least one hydrogen atom of the cycloalkyl group having 3 to 10 carbon atoms is substituted with a fluorine atom. Examples of the cycloalkyl group having 3 to 10 carbon atoms include a cyclopropyl group, a cyclopentyl group, and a cyclohexyl group.

  As the structural unit containing the group represented by the above formula (3-1) and the structural unit containing the group represented by the above formula (3-2), respectively, a structure represented by the following formula (3-1a) Examples thereof include a unit and a structural unit represented by the following formula (3-2a). In addition, examples of the structural unit containing a fluorine atom include a structural unit represented by the following formula (3-3a).

In the above formulas (3-1a), (3-2a) and (3-3a), R ¹² , R ¹⁴ and R ¹⁶ are each independently a hydrogen atom, a methyl group, a fluorine atom or a trifluoromethyl group. It is. In formula (3-1a), R ¹³ is a divalent linking group. In formula (3-2a), R ¹⁵ represents a divalent linking group. R ¹¹ has the same meaning as in formula (3-2). In the formula (3-3a), R ¹⁷ is a fluorinated alkyl group having 1 to 10 carbon atoms or a monovalent fluorinated alicyclic hydrocarbon group having 3 to 10 carbon atoms.

Examples of the divalent linking group represented by R ¹³ include, for example, a linear or branched divalent hydrocarbon group having 1 to 6 carbon atoms and a divalent alicyclic carbon group having 4 to 12 carbon atoms. Examples thereof include a hydrogen group or a group obtained by combining these.

  Examples of the linear or branched divalent hydrocarbon group having 1 to 6 carbon atoms include methylene group, ethylene group, 1,3-propylene group, 1,2-propylene group, and 1,1-propylene. Group, 2,2-propylene group, tetramethylene group, pentamethylene group, hexamethylene group, 1-methyl-1,3-propylene group, 2-methyl-1,3-propylene group, 2-methyl-1,2 -A propylene group, 1-methyl- 1, 4- butylene group, 2-methyl- 1, 4- butylene group etc. are mentioned.

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

As the divalent linking group represented by R ¹⁵ , for example, the groups exemplified as the divalent linking group represented by R ¹³ can be applied.

The fluorinated alkyl group having 1 to 10 carbon atoms represented by R ¹⁷ is a group in which at least one hydrogen atom of the alkyl group having 1 to 10 carbon atoms is substituted with a fluorine atom.

  Examples of the alkyl group having 1 to 10 carbon atoms include linear alkyl groups such as methyl group, ethyl group, n-propyl group, and n-butyl group; i-propyl group, i-butyl group, sec- Examples thereof include branched alkyl groups such as a butyl group and a t-butyl group.

In the monovalent fluorinated alicyclic hydrocarbon group having 3 to 10 carbon atoms represented by R ¹⁷ , at least one hydrogen atom of the monovalent alicyclic hydrocarbon group having 3 to 10 carbon atoms is fluorine. A group substituted with an atom.

  Examples of the monovalent alicyclic hydrocarbon group having 3 to 10 carbon atoms include monocyclic alicyclic hydrocarbon groups such as cyclopentyl group and cyclohexyl group; polycyclic alicyclic rings such as adamantyl group and norbornyl group. A formula hydrocarbon group and the like.

  Examples of the structural unit having a group represented by the above formula (3-1) include structural units represented by the following formulas (3-1-1) to (3-1-8).

In the above formulas (3-1-1) to (3-1-8), R ¹² has the same meaning as the above formula (3-1a). Among these, structural units represented by formulas (3-1-4) and (3-1-8) are preferable.

  Examples of the structural unit having a group represented by the above formula (3-2) include structural units represented by the following formulas (3-2-1) to (3-2-3).

In the above formulas (3-2-1) to (3-2-3), R ¹⁴ has the same meaning as the above formula (3-2a). Among these, the structural unit represented by the formula (3-2-1) is preferable.

  Examples of the structural unit represented by the above formula (3-3a) include structural units represented by the following formulas (3-3-1) to (3-3-6).

In the formulas (3-3-1) to (3-3-6), R ¹⁶ has the same meaning as the formula (3-3a). Among these, structural units represented by formulas (3-3-1) and (3-3-3) are preferable.

  As content rate of the structural unit (I) with respect to all the structural units in a polymer (a), 50 mol% or more is preferable and 80 mol% or more is more preferable. By making the content rate of structural unit (I) into the said specific range, water repellency can be improved effectively, and, thereby, the required characteristic about an elution amount, a Blob defect, and a bridge defect can be made more favorable.

[Structural unit (II)]
The structural unit (II) is a structural unit containing a sulfo group. When the polymer (a) further has the structural unit (II), the resist film can be appropriately reduced by the developer, and as a result, resist pattern defects caused by adhesion of development residues, etc. Can be suppressed. This effect is particularly remarkable in a positive resist.

  Examples of the structural unit (II) include a structural unit represented by the following formula (4).

In the formula (4), R ¹⁸ is a hydrogen atom, a methyl group, a fluorine atom or a trifluoromethyl group. R ¹⁹ is a single bond, an oxygen atom, a sulfur atom, a linear or branched divalent hydrocarbon group having 1 to 6 carbon atoms, a divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms, carbon It is a bivalent aromatic hydrocarbon group or a —C (═O) —X—Y— group of formula 6-12. X is an oxygen atom, a sulfur atom or an NH group. Y is a single bond, a linear or branched divalent hydrocarbon group having 1 to 6 carbon atoms, a divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms, or a divalent group having 6 to 12 carbon atoms. Is an aromatic hydrocarbon group.

Examples of the linear or branched divalent hydrocarbon group having 1 to 6 carbon atoms represented by R ¹⁹ and Y include, for example, methylene group, ethylene group, 1,3-propylene group, 1,2- Propylene group, 1,1-propylene group, 2,2-propylene group, tetramethylene group, pentamethylene group, hexamethylene group, 1-methyl-1,3-propylene group, 2-methyl-1,3-propylene group 2-methyl-1,2-propylene group, 1-methyl-1,4-butylene group, 2-methyl-1,4-butylene group and the like.

Examples of the divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms represented by R ¹⁹ and Y include monocyclic hydrocarbon groups such as a cyclobutylene group, a cyclopentylene group, and a cyclooctylene group. A polycyclic hydrocarbon group such as a norbornylene group or an adamantylene group;

Examples of the divalent aromatic hydrocarbon group having 6 to 12 carbon atoms represented by R ¹⁹ and Y, for example, a phenylene group, such as an arylene group such as a tolylene group. The alicyclic hydrocarbon group and the aromatic hydrocarbon group do not need to be composed of only a ring structure, and may include a chain structure in a part thereof.

  Examples of the structural unit (II) include structural units represented by the following formulas (4-1) to (4-5).

In the above formulas (4-1) to (4-5), R ¹⁸ has the same meaning as the above formula (4). Among these, (4-1) and (4-5) are preferable.

  As content rate of structural unit (II) with respect to all the structural units in a polymer (a), 0.1 to 10 mol% is preferable. By making the content rate of structural unit (II) into the said specific range, a pattern defect can be suppressed effectively.

[Other structural units]
The polymer (a) may have other structural units such as the following structural unit (III) as long as the effects of the present invention are not impaired.

[Structural unit (III)]
The structural unit (III) is a structural unit containing a carboxyl group. When the polymer (a) further includes the structural unit (III), it is possible to further increase the peeling resistance of the liquid immersion upper layer film from the substrate.

  Examples of the structural unit (III) include structural units represented by the following formulas (5-1) to (5-3).

In the above formula ^{(5-1) ~ (5-3),} R 20 represents a hydrogen atom, a methyl group, a fluorine atom or a trifluoromethyl group. R ²¹ in the above formulas (5-1) and (5-2) and R ²² in the above formula (5-1) are each independently a linear or branched group having 1 to 6 carbon atoms. They are a bivalent hydrocarbon group, a C4-C12 bivalent alicyclic hydrocarbon group, or a C6-C12 bivalent aromatic hydrocarbon group.

A linear or branched divalent hydrocarbon group having 1 to 6 carbon atoms represented by R ²¹ and R ²² , a divalent alicyclic hydrocarbon group having 4 to 12 carbon atoms, and 6 carbon atoms. As the divalent aromatic hydrocarbon group of ˜12, for example, the groups exemplified above for R ¹⁹ can be applied.

  As the structural unit represented by the above formula (5-1), for example, structural units represented by the following formulas (5-1-1) to (5-1-3) are represented by the above formula (5-2). Examples of the structural unit represented include structural units represented by the following formulas (5-2-1) to (5-2-2).

上記式（５−１−１）〜（５−２−２）中、Ｒ^２０は、上記式（５−１）〜（５−３）と同義である。

In the above formulas (5-1-1) to (5-2-2), R ²⁰ has the same meaning as the above formulas (5-1) to (5-3).

  When the polymer (a) has the structural unit (III), the content of the structural unit (III) with respect to all the structural units in the polymer (a) is preferably 1 mol% or more and 50 mol% or less. By making the content rate of structural unit (III) into the said specific range, the peeling tolerance from the board | substrate of a liquid immersion upper layer film | membrane can be improved effectively.

  [B] The content of the polymer (a) with respect to the total polymer in the polymer component is preferably 30% by mass or more and 100% by mass or less, and more preferably 50% by mass or more and 100% by mass or less.

<Other polymers>
Other polymer is a polymer which [B] polymer component may contain in the range which does not impair the effect of this invention. The other polymer preferably has a structural unit (II) containing a sulfo group. Furthermore, the other polymer may have other structural units such as the structural unit (III). In addition, since the structure and effect of each said structural unit in another polymer are the same as that of the said polymer (a), the detailed description is abbreviate | omitted. The other polymer may contain two or more of each of the above structural units.

<Method for synthesizing each polymer>
Each of the above polymers can be synthesized, for example, by polymerizing a monomer corresponding to each predetermined structural unit in a suitable polymerization solvent using a polymerization initiator.

  Examples of the polymerization initiator include 2,2′-azobis- (methyl 2-methylpropionate), 2,2′-azobisisobutyronitrile, 2,2′-azobis (4-methoxy-2, 4-dimethylvaleronitrile), 2,2′-azobis (2-cyclopropylpropionitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2-methylpro) Pionitrile), dimethyl 2,2-azobisisobutyrate and the like. These polymerization initiators can be used alone or in combination of two or more.

  The polymerization solvent is not particularly limited as long as radical polymerization is performed as long as it is a solvent other than a solvent that inhibits polymerization (nitrobenzene having a polymerization inhibiting effect, mercapto compound having a chain transfer effect, or the like). Examples of the polymerization solvent include alcohol solvents, ketone solvents, amide solvents, ester / lactone solvents, nitrile solvents, and mixed solvents thereof. These solvents can be used alone or in combination of two or more.

  Each polymer obtained by the polymerization reaction is preferably recovered by a reprecipitation method. That is, after completion of the polymerization reaction, the polymer is recovered as a powder by introducing the polymerization solution into a reprecipitation solvent. As the reprecipitation solvent, alcohols or alkanes can be used alone or in combination of two or more. In addition to the reprecipitation method, each polymer can be recovered by removing low-molecular components by liquid separation operation, column operation, ultrafiltration operation, or the like.

  As a polystyrene conversion weight average molecular weight (Mw) by gel permeation chromatography (GPC) of each polymer, 2,000-100,000 are preferable and 3,000-50,000 are more preferable. If the Mw is less than 2,000, the water resistance and mechanical properties of the liquid immersion upper layer film may be lowered, and if it exceeds 100,000, each polymer may be hardly dissolved in the solvent. Moreover, 1-5 are preferable and, as for ratio (Mw / Mn) of Mw with respect to the polystyrene conversion number average molecular weight (Mn) by GPC, 1-3 are more preferable.

  In addition, Mw and Mn of this specification use the Tosoh GPC column (G2000HXL 2 pieces, G3000HXL 1 piece, G4000HXL 1 piece), flow rate 1.0mL / min, elution solvent tetrahydrofuran, and column temperature of 40 degreeC analysis conditions. Measured by GPC using monodisperse polystyrene as a standard.

<[C] solvent>
[C] The solvent is a solvent that dissolves the [A] compound and the [B] polymer component.

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

  Examples of the alcohol solvent include monohydric alcohols such as butanol, pentanol and 4-methyl-2-pentanol; polyhydric alcohols such as ethylene glycol and propylene glycol.

  Examples of the ether solvents include polyhydric alcohol alkyl ethers 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; ethylene glycol monomethyl Alkyl ether acetates of polyhydric alcohols such as ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate; diethyl ether, dipropyl ether, dibutyl ether, butyl methyl ether, butyl ethyl ether, di Isoamyl ether, Aliphatic ethers such as xylmethyl ether, octyl methyl ether, cyclopentyl methyl ether and dicyclopentyl ether; aliphatic-aromatic ethers such as anisole and phenylethyl ether; cyclic ethers such as tetrahydrofuran, tetrahydropyran and dioxane Can be mentioned.

  Examples of the hydrocarbon solvent include higher hydrocarbons such as decane, dodecene, and untecan.

  Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, methyl-n-pentyl ketone, ethyl-n-butyl ketone, methyl- n-hexyl ketone, di-iso-butyl ketone, trimethylnonanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone, diacetone alcohol, acetophenone, etc. Can be mentioned.

  Examples of the ester solvent include diethyl carbonate, propylene carbonate, methyl acetate, ethyl acetate, γ-valerolactone, n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl acetate, sec-butyl acetate. 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, methyl acetoacetate, Ethyl acetoacetate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol mono-acetate -Butyl ether, propylene glycol monomethyl ether, 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, methoxy acetate Triglycol, ethyl propionate, n-butyl propionate, iso-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate, diethyl malonate , Dimethyl phthalate, diethyl phthalate and the like.

  Among these, ether solvents are preferable. [C] When the solvent contains an ether solvent, elution of the resist film component to the liquid immersion upper layer film at the time of liquid immersion upper layer film formation can be suppressed, and intermixing can be reduced.

<Optional component>
The composition for forming a liquid immersion upper layer film can contain an optional component as long as the effects of the present invention are not impaired. Each optional component can be used alone or in combination of two or more. Moreover, the compounding quantity of an arbitrary component can be suitably determined according to the objective.

<Method for preparing composition for forming liquid immersion upper layer film>
The composition for forming a liquid immersion upper layer film can be prepared by mixing the [A] compound, the [B] polymer component, the [C] solvent and the like at a predetermined ratio.

<Method for forming resist pattern>
A method for forming a resist pattern formed using the composition for forming a liquid immersion upper layer film,
(1) A step of applying a resist composition on a substrate to form a resist film (2) A step of applying the liquid immersion upper layer film forming composition on the resist film to form a liquid immersion upper layer film,
(3) Disposing an immersion medium between the immersion upper layer film and the lens, irradiating radiation through the immersion medium and a mask, and exposing the resist film and the immersion upper layer film; and (4) A step of developing the exposed resist film and immersion upper layer film with a developer to form a resist pattern.

[Step (1)]
This step is a step of applying a resist composition on the substrate to form a resist film. Examples of the substrate include a silicon wafer.

  Examples of the resist composition include a positive or negative chemically amplified resist composition containing an acid generator, a positive resist composition comprising an alkali-soluble resin and a quinonediazide-based photosensitizer, and an alkali-soluble resin and a crosslinking agent. And negative resist compositions composed of an agent. In addition, a commercially available resist composition can also be used as a resist composition. The method for applying the resist composition is not particularly limited, and for example, it can be applied by a known method such as a spin coating method. In addition, when apply | coating a resist composition, the quantity of the resist composition to apply | coat is adjusted so that the resist film formed may become a desired film thickness. In addition, after apply | coating a resist composition on a board | substrate, in order to volatilize a solvent, you may pre-bake (henceforth "PB").

[Step (2)]
This step is a step in which the liquid immersion upper layer film-forming composition is applied onto the resist film to form a liquid immersion upper layer film.

  In this step, it is preferable that the liquid immersion upper layer film forming composition is applied and then baked. Since the immersion medium and the resist film are not in direct contact with each other by this baking, the lithography performance of the resist film due to the immersion medium penetrating into the resist film is deteriorated or the components eluted from the resist film into the immersion medium This effectively prevents the lens of the projection exposure apparatus from being contaminated. As a method for forming 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.

[Step (3)]
This step is a step of exposing the resist film and the liquid immersion upper layer film by irradiating the resist film and the liquid immersion upper film with radiation with an immersion medium interposed between the liquid immersion upper layer film and the lens.

  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 a state where the immersion medium is interposed, that is, in a state where the immersion medium is filled between the lens and the immersion upper layer film, radiation is irradiated from the exposure apparatus, and the resist film is passed through a mask having a predetermined pattern. And exposing the liquid immersion upper layer film.

  Examples of the radiation include visible light; ultraviolet rays such as g rays and i rays; far ultraviolet rays such as excimer lasers; X rays; Among these, an ArF excimer laser (wavelength 193 nm) and a KrF excimer laser (wavelength 248 nm) are preferable. Irradiation conditions such as radiation dose can be appropriately set according to the resist composition, the composition for forming an immersion upper layer film, and the like.

[Step (4)]
This step is a step of developing the exposed resist film and immersion upper layer film with a developer to form a resist pattern. Since the liquid immersion upper film is formed from the composition for forming the liquid immersion upper film, the liquid immersion upper film can be easily removed with a developer, and a special process for removing the liquid immersion upper film is required. And not.

  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, dimethyl. Ethanolamine, triethanolamine, tetraalkylammonium hydroxides (eg, tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide, etc.), pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0 ] An alkaline aqueous solution in which at least one alkaline compound such as -7-undecene and 1,5-diazabicyclo- [4.3.0] -5-nonane is dissolved is preferable. Aqueous solution of Nmo um hydroxides are more preferred. For example, a suitable 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 order to improve the resolution and the like of the resist film, baking after exposure (hereinafter also referred to as “PEB”) is preferably performed before development. The baking temperature can be appropriately set depending on the resist composition to be used, the composition for forming a liquid immersion upper layer film, and the like, but is preferably 30 to 200 ° C, more preferably 50 to 150 ° C.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

<[A] Preparation of Compound>
The compounds represented by the following formulas (A-1), (A-6), (A-7), and (A-9) were manufactured by Tokyo Chemical Industry.

  The compounds represented by the following formulas (A-2), (A-3), (A-4), (A-5), (A-8) and (A-10) were synthesized based on the following documents, respectively. did.

A-2: (Reference 1) Bulletin of the Chemical Society of Japan, 1989, vol. 62, # 4, p. 1179-1187,
A-3: (Reference 2) Journal of the American Chemical Society, 1987, vol. 109, # 24, p. 7488-7494,
A-4: (Reference 3) Journal of Organic Chemistry, 1991, vol. 56, # 21, p. 6199-6205,
A-5: (Reference 4) Journal of Organic Chemistry, 2009, vol. 74, # 23, p. 8988-8996,
A-8: (Reference 5) WO2006 / 1223639
A-10: (Reference 6) Tetrahedron: Asymmetry, 1998, vol. 9, # 15, p. 2619-2626

<[B] Synthesis of polymer component>
Each polymer component was synthesized using monomers represented by the following formulas (M-1) to (M-7).

[Synthesis Example 1] Synthesis of (B-1) A mixed solution in which 0.9 g of 2,2-azobis (methyl 2-methylisopropionate) was dissolved in 0.9 g of methyl ethyl ketone as a polymerization initiator was prepared. On the other hand, in a 200 ml three-necked flask equipped with a thermometer and a dropping funnel, (M-1) 11.8 g (40 mol%), (M-5) 8.2 g (60 mol%), and methyl ethyl ketone 39. 1 g was charged and purged with nitrogen for 30 minutes. After purging with nitrogen, the flask was heated to 75 ° C. while stirring with a magnetic stirrer. Subsequently, using a dropping funnel, a previously prepared mixed solution was dropped over 5 minutes and aged for 360 minutes. Then, it cooled to 30 degrees C or less, and obtained the copolymer liquid.

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 (B-1). The solid content concentration of the solution containing the polymer component (B-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. The obtained polymer component (B-1) has Mw = 9,000, Mw / Mn = 1, 7, yield 70%, and each structure derived from (M-1) and (M-5). The unit content was 40 mol% and 60 mol%, respectively. In addition, ¹ H-NMR, ¹³ C-NMR, and ¹⁹ F-NMR analysis for obtaining the content (mol%) of each structural unit in the [B] polymer component are determined by a nuclear magnetic resonance apparatus (JNM-ECX400, JEOL Ltd.) was used.

[Synthesis Examples 2 to 3] Synthesis of (B-2) to (B-3) Except that the types and amounts of each component are as described in Table 1, the same operations as in Synthesis Example 1 were performed. A coalescence was synthesized. Table 1 shows Mw and Mw / Mn of each polymer.

[Synthesis Example 4] (Synthesis of polymer (B-4))
(M-1) A monomer solution in which 60.57 g (85 mol%) and 4.53 g of 2,2′-azobis- (methyl 2-methylpropionate) as a polymerization initiator are dissolved in 40.00 g of isopropanol. 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 the monomer solution prepared beforehand was dripped over 2 hours using the dropping funnel. After completion of dropping, the reaction was further continued for 1 hour, and 10 g of an isopropanol solution of 3.19 g (15 mol%) of (M-7) was added dropwise over 30 minutes. Then, after reacting for further 1 hour, it cooled to 30 degrees C or less, and obtained the polymerization liquid.

  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 replaced with 4-methyl-2-pentanol to obtain a solution containing the polymer (B-4). Mw of the obtained polymer (B-4) was 9,500, Mw / Mn was 1.8, and the yield was 75%. Moreover, the content rate of each structural unit derived from (M-1) and (M-7) was 98 mol% and 2 mol%, respectively.

[Synthesis Examples 5 to 6] Synthesis of (B-5) to (B-6) Except that the types and amounts of each component were as described in Table 1, the same operations as in Synthesis Example 4 were performed. A coalescence was synthesized. Table 1 shows Mw and Mw / Mn of each polymer.

<Preparation of composition for forming liquid immersion upper layer film>
Each component other than the [A] compound and the [B] polymer component used for the preparation of the composition for forming the liquid immersion upper layer film is shown below.

[C] Solvent C-1: 4-Methyl-2-pentanol C-2: Diisoamyl ether

[Example 1]
[A] 3 parts by mass as compound (A-1), [B] 20 parts by mass as polymer component (B-1) and 80 parts by mass (B-4), and [C] as solvent (C-1) 4,000 parts by mass and (C-2) 1,000 parts by mass were blended to prepare a composition for forming a liquid immersion upper layer film.

[Examples 2 to 12 and Comparative Example 1]
Each composition for forming a liquid immersion upper layer film was prepared in the same manner as in Example 1 except that the type and amount (parts by mass) of each component to be blended were as described in Table 2. In Table 2, the column denoted by “−” indicates that the component is not blended.

<Synthesis of polymer contained in resist composition>
Polymers contained in the resist composition were synthesized using monomers represented by the following formulas (M-8) to (M-10).

[Synthesis Example 17]
In a 500 mL flask, (M-8) 53.9 g (50 mol%), (M-9) 35.4 g (40 mol%), (M-10) 10.7 g (10 mol%), dimethyl 2, 5.6 g of 2′-azobis (2-methylpropionate) and 200 g of 2-butanone were charged, and a polymerization reaction was performed at 80 ° C. for 6 hours under nitrogen. After completion of the polymerization, the polymer solution is cooled to 30 ° C. or lower by water cooling, and then poured into 2,000 g of methanol to precipitate a polymer. After filtering the polymer, 800 g of methanol is added to form a polymer. Was washed. The polymer was further filtered and dried at 50 ° C. for 17 hours to obtain a polymer (P-1) (74 g, yield 74%). This polymer had Mw of 6900 and Mw / Mn of 1.7. As a result of ¹³ C-NMR analysis, the content of each structural unit derived from (M-8), (M-9) and (M-10) was 53 mol%, 37 mol%, 10 mol%, respectively. It was a copolymer.

<Preparation of resist composition>
100 parts by weight of (P-1) polymer, 1.5 parts by weight of triphenylsulfonium nonafluoro-n-butanesulfonate and 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium as the acid generator 6 parts by mass of nonafluoro-n-butanesulfonate and 0.65 parts by mass of R-(+)-(tert-butoxycarbonyl) -2-piperidinemethanol as an acid diffusion controller were mixed, and propylene glycol as a solvent was mixed with this mixture. A resist composition is prepared 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 solid content concentration to 5% by mass, and filtering with a filter having a pore size of 30 nm. Was prepared.

<Evaluation>
Water repellency, elution amount, Blob defect, bridge defect, solution stability, solubility, peeling resistance, and pattern shape were evaluated, and the evaluation results are shown in Table 3.

[Water repellency]
Each liquid immersion upper layer film-forming composition was spin-coated on a silicon wafer, and PB was performed at 90 ° C. for 60 seconds to form a liquid immersion upper layer film having a thickness of 30 nm. Thereafter, the wafer is set on a receding contact angle measuring device (DSA-10, manufactured by KRUS), water is discharged from the needle on the wafer to form a 20 μL water droplet, and once the needle is pulled out of the water droplet, A needle was inserted into the water droplet, and the receding contact angle was measured at a frequency of once per second while sucking the water droplet at a speed of 10 μL / min for 90 seconds with this needle. And the average value of the receding contact angle for 20 seconds after the measurement value was stabilized was calculated, and this value was defined as water repellency (°). It should be noted that if the water repellency is 69 ° or more, the level is practically satisfactory.

[Elution volume]
Silicone rubber with a central part cut out was placed on a silicon wafer, and the cut out part was filled with 10 mL of ultrapure water. Then, another silicon wafer on which the resist film and the liquid immersion upper film were formed was stacked so that the liquid immersion upper film and the ultrapure water were in contact with each other. The resist film was formed by spin coating the resist composition on a wafer and then PB at 115 ° C. for 60 seconds (film thickness 205 nm). Further, the liquid immersion upper layer film was formed by spin-coating each of the liquid immersion upper layer film forming compositions on the resist film and then PB at 90 ° C. for 60 seconds (film thickness 30 nm).

Then, after the immersion upper layer film and the ultrapure water are brought into contact with each other for 10 seconds, the other silicon wafer is removed, and the ultrapure water is recovered and dissolved in the acid generator and the acid diffusion control agent. The amount of elution was measured with a liquid chromatograph mass spectrometer (LC part: SERIES1100 manufactured by AGILENT, MS part: Mariner manufactured by Perseptive Biosystems, Inc.). The measurement uses one column (CAPCELL PAK MG, manufactured by Shiseido), measurement temperature: 35 ° C., flow rate: 0.2 mL / min, effluent solvent: water / methanol (3/7), 0.1% by mass. The formic acid was added. Elution amount if the elution amount in this case the acid generator and the acid diffusion controller both are 5.0 × ¹⁰ -12 mol / cm ² or less good "A", at least one is 5.0 × ¹⁰ -12 mol / If it exceeded cm ² , it was judged as defective “B”.

[Blob defect]
A resist composition was spin-coated on a silicon wafer previously subjected to HMDS (hexamethyldisilazane) treatment at 100 ° C. for 60 seconds, and PB was performed at 90 ° C. for 60 seconds to form a resist film having a thickness of 120 nm. Then, each liquid immersion upper layer forming composition was spin-coated on this resist film, and PB was performed at 90 ° C. for 60 seconds to form a liquid immersion upper layer film having a thickness of 30 nm. Then, it exposed through the plain abrasion glass.

  The formed liquid immersion upper layer film was rinsed with ultrapure water, dried, and then subjected to paddle development for 30 seconds using a 2.38% TMAH aqueous solution to remove the liquid immersion upper layer film. And the undissolved residue of the liquid immersion upper layer film was measured with “KLA2351” (manufactured by KLA Tencor), and this measured value was defined as a Blob defect. At this time, if the number of blob defects is 200 or less, the blob defect is good “A”, and if it exceeds 200, the defect is “B”.

[Bridge defect]
A resist composition was spin-coated on a silicon wafer, and PB was performed at 100 ° C. for 60 seconds to form a resist film having a thickness of 100 nm. Then, each liquid immersion upper layer film-forming composition was applied onto this resist film to form a liquid immersion upper layer film. Then, using an ArF immersion exposure apparatus (S610C, manufactured by NIKON), exposure was performed through a 45 nm line / 90 nm pitch pattern formation mask under the optical conditions of NA: 1.30 and Crosspore. Then, PEB was performed at 100 ° C. for 60 seconds, and after cooling, paddle development was performed for 10 seconds using a 2.38% TMAH aqueous solution, rinsed with ultrapure water, and dried to form a resist pattern. At this time, if no bridge defect was found in the formed resist pattern, the bridge defect was judged as “A”, and if found, it was judged as “B”.

[Solution stability]
Each prepared liquid upper layer film-forming composition was stirred for 30 minutes and then visually confirmed. If it was dissolved without becoming cloudy, the solution stability was good “A”, and if it was cloudy, it was bad “B”. It was.

[Solubility]
Each liquid immersion upper layer film-forming composition was spin coated on a silicon wafer, and PB was performed at 90 ° C. for 60 seconds to form a coating film having a thickness of 90 nm. Then, paddle development was performed for 60 seconds with a 2.38% TMAH aqueous solution, and after drying, the wafer surface was observed. At this time, if there was no residue, the solubility was good “A”, and if the residue was observed, the defect was “B”.

[Peeling resistance]
Each liquid immersion upper film forming composition was spin-coated on a silicon wafer that had not been subjected to HMDS treatment, and PB was performed at 90 ° C. for 60 seconds to form a coating film (liquid immersion upper film) having a thickness of 30 nm. Then, rinsing with pure water was performed for 60 seconds using a semiconductor manufacturing apparatus (CLEAN TRACK ACT8, manufactured by Tokyo Electron), followed by drying. Then, the presence or absence of peeling of the liquid immersion upper layer film is visually observed. If no peeling is observed, the peeling resistance is particularly good “AA”, and if peeling is observed only at the edge portion, the peeling resistance is good “A”. If peeling was observed at the part, it was determined as “B”.

[Pattern shape]
This evaluation was performed to evaluate the formation of a high-resolution resist pattern. Also, a 12-inch silicon wafer was spin-coated with a composition for a lower antireflection film (trade name “ARC66”, manufactured by Nissan Chemical Co., Ltd.) using a trade name “Lithius Pro-i”, and PB (205 ° C., 60 seconds) to form a coating film (lower antireflection film) having a thickness of 105 nm. The resist composition was spin-coated on the formed lower antireflection film, and PB (100 ° C., 60 seconds) was performed to form a coating film (resist film) having a thickness of 100 nm. A liquid immersion upper layer film-forming composition was spin-coated on the formed resist film, and PB (90 ° C., 60 seconds) was performed to form a 30 nm thick coating film (immersion upper layer film). 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. PEB is performed on a Lithius Pro-i hot plate at 100 ° C. for 60 seconds, cooled at 23 ° C. for 30 seconds, and then paddle developed with a 2.38% TMAH aqueous solution as a developer at the GP nozzle of the developing cup. 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 45 nm in a one-to-one line width was determined as the optimum exposure amount. For the measurement, a scanning electron microscope (trade name “CG-4000”, manufactured by Hitachi Keiki Co., Ltd.) was used. Further, the cross-sectional shape of the line-and-space pattern having a line width of 90 nm was observed with a scanning electron microscope (model number “S-4800”, manufactured by Hitachi Instruments). The line width Lb in the middle of the resist film of the formed resist pattern and the line width La at the upper part of the resist film were measured, and the measurement result was used as a pattern shape. At this time, when 0.9 ≦ La / Lb ≦ 1.1, the pattern shape is good “A”, when La / Lb <0.9, or La / Lb> 1.1, it is poor “ B ".

  From the results in Table 3, the liquid immersion upper layer films formed by the liquid immersion upper layer film forming compositions of Examples 1 to 12 had better peeling resistance than those of Comparative Example 1. In addition, the properties of water repellency, elution amount, blob defect, bridge defect, solution stability, solubility and pattern shape were good, and the required characteristics were well-balanced.

  According to the composition for forming a liquid immersion upper layer film of the present invention, while maintaining the required properties of water repellency, elution amount, blob defect, bridge defect, solution stability, solubility and pattern shape, resistance to peeling from the substrate And a liquid immersion upper film that can satisfy these required characteristics in a well-balanced manner can be formed. Therefore, the composition for forming a liquid immersion upper layer film can be suitably applied to a semiconductor device manufacturing process in which further miniaturization of a resist pattern proceeds.

Claims (7)

[A] a compound having a molecular weight of 100 or more and 1,000 or less represented by the following formula (1):
[B] A polymer component containing the polymer (a) having the structural unit (I) containing a fluorine atom, and [C] a composition for forming an immersion upper layer film containing a solvent.

(In the formula (1), R ¹ is a hydrogen atom, a halogen atom, a nitro group, an alkyl group, an alicyclic hydrocarbon group, an alkoxy group, an acyl group, an aralkyl group or an aryl group, provided that the alkyl group, Some or all of the hydrogen atoms of the alicyclic hydrocarbon group, alkoxy group, acyl group, aralkyl group and aryl group may be substituted, and R ² represents —C (═O) —R ³ , —S (═O) ₂ —R ⁴ , —R ⁵ —CN or —R ⁶ —NO _{2. The} above R ³ represents a hydrogen atom, an alkyl group, a fluorinated alkyl group, an alicyclic hydrocarbon group , a An ano group, a cyanomethyl group, an aralkyl group or an aryl group , wherein R ⁴ represents a hydrogen atom, an alkyl group, a fluorinated alkyl group, an alicyclic hydrocarbon group, an alkoxy group, a cyano group, a cyanomethyl group, an aralkyl group or an aryl group; a group. And combines the ^{R 3} or ^{R 4} and ^{R 1} and each other, together with the carbon atom ^{to which R 2} and ^{R 1} is attached may form a ring structure. The above ^{R 5} and ^{R 6} are each independently A single bond, a methylene group or an alkylene group having 2 to 5 carbon atoms, R ⁷ is a monovalent organic group, provided that R ⁷ and R ¹ are bonded to each other, and R ⁷ is (A ring structure may be formed together with the carbon atom to which R ¹ is bonded and the carbon atom to which R ¹ is bonded.) R ¹ in the above formula (1) is a hydrogen atom, a nitro group, an alkyl group, an alicyclic hydrocarbon group, an alkoxy group or an acyl group, and the above R ² is —C (═O) —R ³ , — The composition for forming a liquid immersion upper layer film according to claim 1, wherein the composition is S (═O) ₂ —R ⁴ or —R ⁵ —CN. The composition for forming a liquid immersion upper layer film according to claim 1 or 2, wherein the organic group of R ⁷ in the formula (1) is represented by the following formula (2).

(In the formula (2), R ⁸ is a monovalent hydrocarbon group, provided that R ⁸ and R ¹ are bonded to each other, and the carbon atom to which R ⁷ is bonded and R ¹ are bonded. A ring structure may be formed together with the carbon atom.)   The content of [A] compound is 0.1 to 100 parts by mass with respect to 100 parts by mass of [B] polymer component. Composition for forming an upper layer film. The structural unit (I) is at least one selected from the group consisting of a structural unit containing a group represented by the following formula (3-1) and a structural unit containing a group represented by the following formula (3-2) The composition for forming a liquid immersion upper layer film according to any one of claims 1 to 4, wherein the composition is a structural unit.

(In Formula (3-1), R ⁹ and R ¹⁰ are a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a fluorinated alkyl group having 1 to 4 carbon atoms, provided that R ⁹ and R ¹⁰ are Among these, at least one is a C1-C4 fluorinated alkyl group.
In formula (3-2), R ¹¹ represents a fluorinated alkyl group having 1 to 10 carbon atoms or a fluorinated cycloalkyl group having 3 to 10 carbon atoms. )   [B] The liquid according to any one of claims 1 to 5, wherein the polymer component further has a structural unit (II) containing a sulfo group in the same or different polymer as the polymer (a). A composition for forming a submerged layer film.   [C] The composition for forming a liquid immersion upper layer film according to any one of claims 1 to 6, wherein the solvent contains an ether solvent.