JP2008285540A - Polymer for upper layer film for immersion exposure and resin composition for upper layer film for immersion exposure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polymer and a resin composition for an upper layer film for immersion exposure that have sufficient transmissibility within the wavelength range of a radiation, can form a protecting film on a photoresist film without causing intermixing with the photoresist film, exhibits sufficient oil repellence to hardly cause liquid remaining on the film on high-speed scanning and can form an upper layer film having a sufficiently high refractive index corresponding to high NA exposure. <P>SOLUTION: The polymer for the upper layer film can form a film having a contact angle of at least 65° and less than 90° with trans-decahydronaphthalene, 1,1-bicylcohexyl and exo-tetrahydrodicyclopentadiene and having a refractive index of at least 1.6 and at most 1.8 at 193 nm and has a weight-average molecular weight of 2,000-100,000. The polymer for the upper layer film comprises a recurring unit having a fluorine atom-bearing group in its side chain and a recurring unit having a sulfur atom-bearing group in its side chain. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention provides an immersion liquid useful for protecting a photoresist during immersion exposure used for lithography miniaturization and for forming an upper layer film that suppresses elution of a photoresist component and protects a lens of a projection exposure apparatus. The present invention relates to an upper layer film-forming resin composition for liquid use, and a liquid immersion upper layer film polymer that can be used for the upper layer film.

Stepper-type or step-and-scan projection exposure that transfers a reticle pattern as a photomask to each shot area on a wafer coated with photoresist via a projection optical system when manufacturing semiconductor elements, etc. The device is in use.
The theoretical limit value of the resolution of the projection optical system provided with the projection exposure apparatus becomes higher as the exposure wavelength used is shorter and the numerical aperture of the projection optical system is larger. For this reason, with the miniaturization of integrated circuits, the exposure wavelength, which is the wavelength of radiation used in the projection exposure apparatus, has become shorter year by year, and the numerical aperture of the projection optical system has also increased.
As described above, in the field of manufacturing semiconductor devices, conventionally, the demand for miniaturization of integrated circuits has been met by shortening the exposure wavelength and increasing the numerical aperture. Currently, an ArF excimer laser (wavelength 193. Mass production of 1L1S (1: 1 line and space) half pitch 90 nm nodes using 4 nm) is under study. However, it is said that it is difficult to achieve the next generation half pitch 65 nm node or 45 nm node, which is further miniaturized, by using only an ArF excimer laser. Therefore, the use of short wavelength light sources such as F ₂ excimer laser (wavelength 157 nm), EUV (wavelength 13 nm), etc. has been studied for these next-generation technologies. However, the use of these light sources is technically difficult and is still difficult to use.

In the above exposure technique, a photoresist film is formed on the surface of the wafer to be exposed, and a pattern is transferred to the photoresist film. In a conventional projection exposure apparatus, a space in which a wafer is placed is viewed with air or nitrogen having a refractive index of 1.
However, by filling a liquid having a refractive index n between the lens of the projection exposure apparatus and the wafer and setting an appropriate optical system, the resolution limit value and the focal depth can be increased to 1 / n and n times, respectively. It is theoretically possible. For example, when water is used as a liquid that fills the space between the lens and wafer in a process using an ArF excimer laser as the exposure light source, the refractive index n of light having a wavelength of 193.4 nm in water is 1.44. Compared to the exposure using a medium, it is theoretically possible to design an optical system with a resolution of 69.4% and a focal depth of 144%.
A projection exposure method capable of shortening the effective wavelength of light for exposure and transferring a finer pattern is called immersion exposure. This technology is indispensable for future miniaturization of lithography, especially lithography in 10 nm units. It is believed that.

The applicant of the present application has a refractive index larger than that of conventional pure water in the immersion exposure method, has excellent transparency, prevents elution and dissolution of the photoresist film or its upper layer film component (especially hydrophilic component), As a result of investigating various compounds for the purpose of providing an immersion exposure liquid capable of forming a pattern with better resolution and depth of focus when used as an immersion liquid without eroding the lens, An alicyclic saturated hydrocarbon compound such as decahydronaphthalene, which has low absorption in the region and has a high refractive index suitable as a liquid for immersion exposure, has been found and has been applied for a patent (Patent Document 1).
In addition, as an upper layer film used when water is used as the immersion medium, a film including a repeating unit having a group containing a fluorine atom in its side chain and having a contact angle with water of 90 ° or more is formed. The present applicant has filed a patent application for a polymer that can be used (Patent Document 2).

However, since the immersion medium of the alicyclic saturated hydrocarbon compound comes into contact with the resist during exposure, it may penetrate into the photoresist film and deteriorate the resolution of the photoresist or cause development defects. In particular, when the oil repellency of the resist is low, there is a problem that the liquid remains on the resist after scanning and easily penetrates into the resist film.
As a countermeasure against these problems, there is a method of forming an upper layer film on the photoresist film. However, this upper layer film has sufficient permeability to the wavelength of the radiation and does not cause intermixing with the photoresist film. is necessary. In addition, the film must have sufficient oil repellency, no liquid residue on the film during high-speed scanning, and a sufficient refractive index to support high NA exposure, but these characteristics are satisfied. There is a problem that an upper layer film cannot be obtained.
WO2005 / 114711 JP 2006-335916 A

  The present invention has been made to overcome such problems, and has a sufficient transparency to the wavelength of radiation, and can form a protective film on the photoresist film without causing intermixing with the photoresist film. Furthermore, a liquid immersion upper film polymer and a liquid immersion upper layer capable of forming an upper film having sufficient oil repellency, little liquid remaining on the film during high-speed scanning, and having a sufficiently high refractive index corresponding to high NA exposure. It aims at provision of the resin composition for membranes.

The polymer for an immersion upper layer film of the present invention has a contact angle with an immersion liquid composed of a saturated hydrocarbon compound of 65 ° or more and less than 90 °, and a refractive index at 193 nm of 1.6 or more and 1.8. The following film | membrane can be formed and the weight average molecular weights measured by the gel permeation chromatography method are 2,000-100,000, It is characterized by the above-mentioned.
The saturated hydrocarbon compound is at least one saturated hydrocarbon compound selected from trans-decahydronaphthalene, 1,1-bicyclohexyl, and exo-tetrahydrodicyclopentadiene.

Ｒ¹、Ｒ²、Ｒ³は、それぞれ独立に、水素原子またはメチル基を表し、Ｒｆは少なくとも一部の水素原子がフッ素原子で置換された１価のフッ素化炭化水素基を表す。
上記硫黄原子を含む基をその側鎖に有する繰返し単位は、下記の式（２）で表されることを特徴とする。

Ｒ⁴、Ｒ⁵、Ｒ⁶は、水素原子またはメチル基を表し、Ｒsは硫黄原子を含む１価の有機基を表す。 The polymer for an immersion upper layer film of the present invention includes a repeating unit having a group containing a fluorine atom in its side chain and a repeating unit having a group containing a sulfur atom in its side chain.
Further, the repeating unit having a group containing a fluorine atom in its side chain is represented by the following formula (1).

R ¹ , R ² and R ³ each independently represents a hydrogen atom or a methyl group, and Rf represents a monovalent fluorinated hydrocarbon group in which at least a part of the hydrogen atoms are substituted with fluorine atoms.
The repeating unit having a group containing a sulfur atom in its side chain is represented by the following formula (2).

R ⁴ , R ⁵ and R ⁶ each represent a hydrogen atom or a methyl group, and Rs represents a monovalent organic group containing a sulfur atom.

  The immersion upper layer film-forming resin composition of the present invention is an immersion upper layer film-forming resin composition for forming an upper layer film to be coated on a photoresist film subjected to immersion exposure, and the resin composition comprises: The above-mentioned liquid immersion upper layer polymer is dissolved in an alcohol solvent.

  The polymer for an immersion upper layer film of the present invention has a contact angle with an immersion liquid composed of a saturated hydrocarbon compound of 65 ° or more and less than 90 °, and a refractive index at 193 nm of 1.6 or more and 1.8. Since the following film can be formed, an upper layer film having oil repellent property and a small amount of immersion liquid remaining on the upper layer film during high-speed scanning and having a sufficiently high refractive index corresponding to high NA exposure can be formed. .

The polymer constituting the upper film forming composition for immersion according to the present invention has a contact angle with an immersion liquid comprising a saturated hydrocarbon compound of 65 ° or more and less than 90 °, preferably 65 ° to 80 °. , A polymer capable of forming a film having a refractive index at 193 nm of 1.6 or more and 1.8 or less.
The contact angle with the immersion liquid is such that when the upper layer film is formed under the upper layer film forming conditions in each example described later, the surface of the upper layer film and the saturated hydrocarbon compound, in particular, the transmittance at 193 nm is 95% or more. The contact angle with a certain trans-decahydronaphthalene, 1,1-bicyclohexyl, or exo-tetrahydrodicyclopentadiene. This contact angle is measured using DSA-10 made by KRUS, and 0.05 ml of the test saturated hydrocarbon compound is dropped on the substrate on which the coating film is formed, and the contact angle after 3 to 10 seconds after dropping is measured. Measurements were taken every second, and the average value was determined as the contact angle.
If the contact angle is less than 65 °, the liquid residue tends to increase at the time of scanning. If the contact angle is 90 ° or more, bubbles tend to be generated at the interface with the resist and development defects tend to be generated.

  The refractive index of the polymer at 193 nm was determined using a high-speed spectroscopic ellipsometer M-2000 (manufactured by JA Woollam). If the refractive index is less than 1.6, the resolution may decrease at high NA, and if it exceeds 1.8, reflection occurs at the interface with the liquid and the throughput tends to decrease.

Ｒ¹、Ｒ²、Ｒ³は、それぞれ独立に、水素原子またはメチル基を表し、Ａは、単結合、酸素原子、カルボニル基、カルボニルオキシ基、オキシカルボニル基を表し、Ｂは、単結合、炭素数１〜２０の２価の有機基を表し、Ｘは１価の有機基を表し、ｎは１〜２０の整数を表す。
ＡおよびＢで表される炭素数１〜２０の２価の有機基としては、メチレン基、エチレン基、１，３−プロピレン基もしくは１，２−プロピレン基などのプロピレン基、テトラメチレン基、ペンタメチレン基、ヘキサメチレン基、ヘプタメチレン基、オクタメチレン基、ノナメチレン基、デカメチレン基、ウンデカメチレン基、ドデカメチレン基、トリデカメチレン基、テトラデカメチレン基、ペンタデカメチレン基、ヘキサデカメチレン基、ヘプタデカメチレン基、オクタデカメチレン基、ノナデカメチレン基、インサレン基、１−メチル−１，３−プロピレン基、２−メチル−１，３−プロピレン基、２−メチル−１，２−プロピレン基、１−メチル−１，４−ブチレン基、２−メチル−１，４−ブチレン基、メチリデン基、エチリデン基、プロピリデン基、または、２−プロピリデン基等の飽和鎖状炭化水素基、１，３−シクロブチレン基などのシクロブチレン基、１，３−シクロペンチレン基などのシクロペンチレン基、１，４−シクロヘキシレン基などのシクロヘキシレン基、１，５−シクロオクチレン基などのシクロオクチレン基等の炭素数３〜１０のシクロアルキレン基などの単環式炭化水素環基、１，４−ノルボルニレン基もしくは２，５−ノルボルニレン基などのノルボルニレン基、１，５−アダマンチレン基、２，６−アダマンチレン基などのアダマンチレン基等の２〜４環式炭素数４〜２０の炭化水素環基などの架橋環式炭化水素環基等が挙げられる。 The repeating unit having a group containing a fluorine atom in its side chain is a repeating unit capable of increasing the contact angle with water, and is preferably a repeating unit having a fluorinated alkylene group in the side chain.
As a monomer which produces | generates the repeating unit which has a fluorinated alkylene group in a side chain, the monomer represented by following formula (3) is mentioned.

R ¹ , R ² and R ³ each independently represents a hydrogen atom or a methyl group, A represents a single bond, an oxygen atom, a carbonyl group, a carbonyloxy group or an oxycarbonyl group, and B represents a single bond, A divalent organic group having 1 to 20 carbon atoms is represented, X represents a monovalent organic group, and n represents an integer of 1 to 20.
Examples of the divalent organic group having 1 to 20 carbon atoms represented by A and B include a propylene group such as a methylene group, an ethylene group, a 1,3-propylene group or a 1,2-propylene group, a tetramethylene group, and a pentane group. Methylene group, hexamethylene group, heptamethylene group, octamethylene group, nonamethylene group, decamethylene group, undecamethylene group, dodecamethylene group, tridecamethylene group, tetradecamethylene group, pentadecamethylene group, hexadecamethylene group, Heptadecamethylene group, Octadecamethylene group, Nonadecamethylene group, Insalene 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, methylidene group, ethylidene group A propylidene group, a saturated chain hydrocarbon group such as a 2-propylidene group, a cyclobutylene group such as a 1,3-cyclobutylene group, a cyclopentylene group such as a 1,3-cyclopentylene group, 1,4- Monocyclic hydrocarbon ring groups such as cycloalkylene groups having 3 to 10 carbon atoms such as cyclohexylene groups such as cyclohexylene groups, cyclooctylene groups such as 1,5-cyclooctylene groups, 1,4-norbornylene groups Alternatively, a hydrocarbon ring group having 2 to 4 cyclic carbon atoms such as a norbornylene group such as 2,5-norbornylene group, an adamantylene group such as 1,5-adamantylene group, 2,6-adamantylene group, etc. And a crosslinked cyclic hydrocarbon ring group.

X represents a hydrogen atom, a halogen atom, a hydroxyl group, or a cyano group. As the halogen atom, a fluorine atom is preferable because the contact angle with water can be improved.
n is an integer of 1-20. When n exceeds 20, scum and development defects tend to remain when developed with an alkaline developer. The perfluoroalkylene group represented by (CF ₂ ) _n may be linear or branched. Preferably, it is a linear perfluoroalkylene group that can improve the contact angle with water.

Ｒ¹、Ｒ²、Ｒ³は、それぞれ独立に、水素原子またはメチル基を表し、Ｒｆは少なくとも一部の水素原子がフッ素原子で置換された１価のフッ素化炭化水素基を表す。
好ましいＲｆは炭素数１〜２０のフッ素置換炭化水素基であり、具体的にはメチル基、エチル基、プロピル基、ブチル基、ペンチル基、ヘキシル基、ヘプチル基、オクチル基、ノニル基、デシル基、ウンデシル基、ドデシル基、トリデシル基、テトラデシル基、ペンタデシル基、ヘキサデシル基、ヘプタデシル基、オクタデシル基、ノナデシル基、イコシル基の一部の水素をフッ素置換した基が挙げられる。
より好ましいＲｆとしてはパーフルオロメチル基、パーフルオロエチル基、パーフルオロプロピル基、パーフルオロブチル基、パーフルオロペンチル基、パーフルオロヘキシル基、パーフルオロヘプチル基、パーフルオロオクチル基、パーフルオロノニル基、パーフルオロウンデシル基、パーフルオロドデシル基、パーフルオロトリデシル基、パーフルオロテトラデシル基、パーフルオロペンタデシル基、パーフルオロヘキサデシル基、パーフルオロヘプタデシル基、パーフルオロオクタデシル基、パーフルオロノナデシル基、パーフルオロイコシル基、パーフルオロメチルメチル基、パーフルオロエチルメチル基、パーフルオロプロピルメチル基、パーフルオロブチルメチル基、パーフルオロペンチルメチル基、パーフルオロヘキシルメチル基、パーフルオロヘプチルメチル基、パーフルオロオクチルメチル基、パーフルオロノニルメチル基、パーフルオロウンデシルメチル基、パーフルオロドデシルメチル基、パーフルオロトリデシルメチル基、パーフルオロテトラデシルメチル基、パーフルオロペンタデシルメチル基、パーフルオロヘキサデシルメチル基、パーフルオロヘプタデシルメチル基、パーフルオロオクタデシルメチル基、パーフルオロノナデシルメチル基、パーフルオロメチルエチル基、パーフルオロエチルエチル基、パーフルオロプロピルエチル基、パーフルオロブチルエチル基、パーフルオロペンチルエチル基、パーフルオロヘキシルエチル基、パーフルオロヘプチルエチル基、パーフルオロオクチルエチル基、パーフルオロノニルエチル基、パーフルオロウンデシルエチル基、パーフルオロドデシルエチル基、パーフルオロトリデシルエチル基、パーフルオロテトラデシルエチル基、パーフルオロペンタデシルエチル基、パーフルオロヘキサデシルエチル基、パーフルオロヘプタデシルエチル基、パーフルオロオクタデシルエチル基、パーフルオロメチルプロピル基、パーフルオロエチルプロピル基、パーフルオロプロピルプロピル基、パーフルオロブチルプロピル基、パーフルオロペンチルプロピル基、パーフルオロヘキシルプロピル基、パーフルオロヘプチルプロピル基、パーフルオロオクチルプロピル基、パーフルオロノニルプロピル基、パーフルオロウンデシルプロピル基、パーフルオロドデシルプロピル基、パーフルオロトリデシルプロピル基、パーフルオロテトラデシルプロピル基、パーフルオロペンタデシルプロピル基、パーフルオロヘキサデシルプロピル基、パーフルオロヘプタデシルプロピル基が挙げられる。 Examples of preferred monomers include (meth) acrylates having a perfluoroalkylene group represented by the following formula (1a) in the side chain.

R ¹ , R ² and R ³ each independently represents a hydrogen atom or a methyl group, and Rf represents a monovalent fluorinated hydrocarbon group in which at least a part of the hydrogen atoms are substituted with fluorine atoms.
Preferred Rf is a fluorine-substituted hydrocarbon group having 1 to 20 carbon atoms, specifically, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group. , A group obtained by substituting a part of hydrogens of undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group and icosyl group with fluorine.
More preferable Rf is a perfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, a perfluorohexyl group, a perfluoroheptyl group, a perfluorooctyl group, a perfluorononyl group, Perfluoroundecyl group, perfluorododecyl group, perfluorotridecyl group, perfluorotetradecyl group, perfluoropentadecyl group, perfluorohexadecyl group, perfluoroheptadecyl group, perfluorooctadecyl group, perfluorononadecyl group Group, perfluoroicosyl group, perfluoromethylmethyl group, perfluoroethylmethyl group, perfluoropropylmethyl group, perfluorobutylmethyl group, perfluoropentylmethyl group, perfluorohexylmethyl Group, perfluoroheptylmethyl group, perfluorooctylmethyl group, perfluorononylmethyl group, perfluoroundecylmethyl group, perfluorododecylmethyl group, perfluorotridecylmethyl group, perfluorotetradecylmethyl group, perfluoropenta Decylmethyl, perfluorohexadecylmethyl, perfluoroheptadecylmethyl, perfluorooctadecylmethyl, perfluorononadecylmethyl, perfluoromethylethyl, perfluoroethylethyl, perfluoropropylethyl, Fluorobutylethyl, perfluoropentylethyl, perfluorohexylethyl, perfluoroheptylethyl, perfluorooctylethyl, perfluorononylethyl, perfluoro Decylethyl group, perfluorododecylethyl group, perfluorotridecylethyl group, perfluorotetradecylethyl group, perfluoropentadecylethyl group, perfluorohexadecylethyl group, perfluoroheptadecylethyl group, perfluorooctadecylethyl group, Perfluoromethylpropyl group, perfluoroethylpropyl group, perfluoropropylpropyl group, perfluorobutylpropyl group, perfluoropentylpropyl group, perfluorohexylpropyl group, perfluoroheptylpropyl group, perfluorooctylpropyl group, perfluoro Nonylpropyl group, perfluoroundecylpropyl group, perfluorododecylpropyl group, perfluorotridecylpropyl group, perfluorotetradecylpropyl group, -Fluoropentadecylpropyl group, perfluorohexadecylpropyl group, perfluoroheptadecylpropyl group.

Ｒ⁴、Ｒ⁵、Ｒ⁶は水素原子またはメチル基を表す。また、Ｒsは硫黄原子を含む１価の有機基を表し、Ｒsとしては式（２）のカルボニル基の炭素原子が硫黄原子で連結される下記の環式または複素環式硫黄含有基が挙げられる。

上記Ｒs基を有する式（２）で表される繰返し単位を生成するラジカル重合性単量体は、（メタ）アクリル酸クロリドと環構造を有するチオールとを塩基性条件にて反応させチオエステル化することにより合成できる。 The repeating unit having a group containing a sulfur atom in its side chain is a repeating unit that improves developability and is represented by the formula (2).

R ⁴ , R ⁵ and R ⁶ represent a hydrogen atom or a methyl group. Rs represents a monovalent organic group containing a sulfur atom, and examples of Rs include the following cyclic or heterocyclic sulfur-containing groups in which the carbon atom of the carbonyl group of formula (2) is linked by a sulfur atom. .

The radical polymerizable monomer that generates the repeating unit represented by the formula (2) having the Rs group reacts (meth) acrylic acid chloride with a thiol having a ring structure under basic conditions to form a thioester. Can be synthesized.

  The polymer of the present invention comprises a repeating unit represented by formula (1) and a repeating unit represented by formula (2), a repeating unit having a carboxyl group in a side chain, and a repeating unit represented by formula (2) In addition, a repeating unit having a sulfo group in the side chain, or a repeating unit having an alcoholic hydroxyl group having a fluoroalkyl group at the α-position in the side chain can be included.

Examples of the radical polymerizable monomer that generates a repeating unit having a carboxyl group in the side chain include (meth) acrylic acid, crotonic acid, cinnamic acid, atropic acid, 3-acetyloxy (meth) acrylic acid, and 3-benzoyl. Unsaturated monocarboxylic acids such as oxy (meth) acrylic acid, α-methoxyacrylic acid and 3-cyclohexyl (meth) acrylic acid; unsaturated polycarboxylic acids such as fumaric acid, maleic acid, citraconic acid, mesaconic acid and itaconic acid Monoesters of the unsaturated polycarboxylic acid such as monomethyl ester, monoethyl ester, mono n-propyl ester, mono n-butyl ester; 2- (meth) acrylamide-2-methylpropanecarboxylic acid, 2-α- Carboxyacrylamide-2-methylpropane carboxylic acid, 2-α-carboxymethyl acrylate Amido-2-methylpropanecarboxylic acid, 2-α-methoxycarbonylacrylamide-2-methylpropanecarboxylic acid, 2-α-acetyloxyacrylamide-2-methylpropanecarboxylic acid, 2-α-phenylacrylamide-2-methylpropane Carboxylic acid, 2-α-benzylacrylamide-2-methylpropanecarboxylic acid, 2-α-methoxyacrylamide-2-methylpropanecarboxylic acid, 2-α-cyclohexylacrylamide-2-methylpropanecarboxylic acid, 2-α-cyano And acrylamide-2-methylpropanecarboxylic acid.
Of the above, (meth) acrylic acid and crotonic acid are preferred.

  Examples of the radical polymerizable monomer that generates a repeating unit having a sulfo group in the side chain include vinyl sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methyl-1-propanesulfonic acid, 4-vinyl- Examples include 1-benzenesulfonic acid. Of these sulfonic acid monomers, vinyl sulfonic acid and allyl sulfonic acid are particularly preferred.

The polymer of the present invention can be copolymerized with other radical polymerizable monomers for the purpose of controlling the molecular weight of the resin, the glass transition point, and the like. “Other” means a radical polymerizable monomer other than the above-mentioned radical polymerizable monomers. Moreover, an acid dissociable group-containing monomer can be copolymerized.
Other radical polymerizable monomers or acid dissociable group-containing monomers include (meth) acrylic acid alkyl esters, (meth) acrylic acid aryl esters, dicarboxylic acid diesters, nitrile group-containing radical polymerizable monomers. Examples include a monomer, an amide bond-containing radical polymerizable monomer, a fatty acid vinyl, a chlorine-containing radical polymerizable monomer, a conjugated diolefin, and a hydroxyl group-containing (meth) acrylic acid alkyl ester.
Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, isopropyl (meth) acrylate, n-hexyl (Meth) acrylate, cyclohexyl (meth) acrylate, 2-methylcyclohexyl (meth) acrylate, dicyclopentanyloxyethyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, methoxydipropylene glycol (Meth) acrylate, butoxy-dipropylene glycol (meth) acrylate, methoxydiethylene glycol (meth) acrylate, methoxypropylene glycol (meth) acrylate, 2-methyl 2-adamantyl (meth) acrylate, 2-ethyl-2-adamantyl (meth) acrylate, 2-propyl-2-adamantyl (meth) acrylate, 2-butyl-2-adamantyl (meth) acrylate, 1- Methyl-1-cyclohexyl (meth) acrylate, 1-ethyl-1-cyclohexyl (meth) acrylate, 1-propyl-1-cyclohexyl (meth) acrylate, 1-butyl-1-cyclohexyl (meth) acrylate, 1-methyl-1-cyclopentyl (meth) acrylate, 1-ethyl-1-cyclopentyl (meth) acrylate, 1-propyl-1-cyclopentyl (meth) acrylate, 1-butyl-1-cyclopentyl (meth) acryl Rate, 1-adamantyl-1-methyl ester (Meth) acrylic acid alkyl esters such as ru (meth) acrylate, 1-bicyclo [2.2.1] heptyl-1-methylethyl (meth) acrylate; diethyl maleate, diethyl fumarate, diethyl itaconate, etc. Dicarboxylic acid diesters of (meth) acrylic acid aryl esters such as phenyl (meth) acrylate and benzyl (meth) acrylate; styrene, α-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, p-methoxy Aromatic vinyls such as styrene, radical polymerizable monomers containing nitrile groups such as acrylonitrile and methacrylonitrile; radical polymerizable monomers containing amide bonds such as acrylamide, methacrylamide and trifluoromethanesulfonylaminoethyl (meth) acrylate Body; fatty acid vinyls such as vinyl acetate; chlorine-containing radical polymerizable monomers such as vinyl chloride and vinylidene chloride; and conjugated diolefins such as 1,3-butadiene, isoprene and 1,4-dimethylbutadiene may be used. it can.
Examples of the hydroxyl group-containing (meth) acrylic acid alkyl ester include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) ) Acrylate, 2,3-dihydroxypropyl (meth) acrylate, polypropylene glycol (meth) acrylate, 2-hydroxycyclohexyl (meth) acrylate, 4-hydroxycyclohexyl (meth) acrylate, 3-hydroxy-1- Examples thereof include adamantyl (meth) acrylate, 3,5-dihydroxy-1-adamantyl (meth) acrylate, and among these, 2-hydroxyethyl (meth) acrylate and 3-hydroxy-1-adamantyl. Meth) acrylate are preferable.
These monomers can be used alone or in combination of two or more.

The polymer of this invention contains 10-80 mol% of the repeating unit represented by said Formula (1) with respect to all the repeating units which comprise a polymer, Preferably it contains 20-75 mol%. If it is less than 10 mol%, it becomes difficult for the contact angle with water to be 65 ° or more. On the other hand, if it exceeds 80 mol%, the solubility in an alkaline aqueous solution as a developer is lowered, and the upper layer film cannot be removed, and a residue may be generated on the resist pattern after development.
The repeating unit represented by the formula (2) is contained in an amount of 10 to 70 mol%, preferably 20 to 60 mol%, based on all repeating units constituting the polymer. If it is less than 10 mol%, the refractive index at 193 nm will be low, and if it exceeds 70 mol%, the contact angle of the coating film with the immersion liquid will not be sufficiently large.
Further, when it contains a repeating unit having a carboxyl group, a sulfo group, or an alcoholic hydroxyl group having a fluoroalkyl group at the α-position in the side chain, the carboxyl group-containing repeating unit is 5 to 40 mol%, and the sulfo group-containing repeating unit is 5 It is preferable to contain -40 mol% of alcoholic hydroxyl group-containing repeating units having a fluoroalkyl group at the α-position and 5-40 mol%. When the repeating unit is outside the above range, solubility in an alkaline aqueous solution as a developer is lowered. The repeating unit derived from the other radical polymerizable monomer is 30 mol% or less.

  Examples of the polymerization solvent used when producing the polymer of the present invention include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, ethylene glycol, diethylene glycol, and propylene glycol; Cyclic ethers such as tetrahydrofuran and dioxane; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, Propylene glycol monomethyl Alkyl ethers of polyhydric alcohols such as ether and propylene glycol monoethyl ether; alkyl ether acetates of polyhydric alcohols such as ethylene glycol ethyl ether acetate, diethylene glycol ethyl ether acetate, propylene glycol ethyl ether acetate, propylene glycol monomethyl ether acetate; Aromatic hydrocarbons such as toluene and xylene; Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, 4-hydroxy-4-methyl-2-pentanone, diacetone alcohol; ethyl acetate, butyl acetate, 2-hydroxy Ethyl propionate, ethyl 2-hydroxy-2-methylpropionate, ethyl 2-hydroxy-2-methylpropionate , Ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutanoate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, ethyl acetate, Examples include esters such as butyl acetate. Of these, cyclic ethers, alkyl ethers of polyhydric alcohols, alkyl ether acetates of polyhydric alcohols, ketones, and esters are preferable.

  Moreover, as a polymerization catalyst in radical polymerization, a normal radical polymerization initiator can be used, for example, 2,2′-azobisisobutyronitrile, 2,2′-azobis- (methyl 2-methylpropionate), 2 Azo compounds such as 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobis- (4-methoxy-2-dimethylvaleronitrile); benzoyl peroxide, lauroyl peroxide, tert-butylperoxypi Mention may be made of organic peroxides such as barate, 1,1′-bis- (tert-butylperoxy) cyclohexane, hydrogen peroxide, and the like. When a peroxide is used as a radical polymerization initiator, a redox initiator may be combined with a reducing agent.

The weight average molecular weight (hereinafter abbreviated as Mw) of the polymer obtained by the above method is usually 2,000 to 100,000, preferably 2,500 to 50,000, in terms of polystyrene by gel permeation chromatography. Preferably it is 3,000-20,000. In this case, when the Mw of the polymer is less than 2,000, the water resistance and mechanical properties as the upper layer film are remarkably low. On the other hand, when it exceeds 100,000, the solubility in a solvent described later is remarkably poor. The ratio (Mw / Mn) of the resin Mw to the polystyrene-equivalent number average molecular weight (hereinafter abbreviated as Mn) by gel permeation chromatography (GPC) is usually 1 to 5, preferably 1 to 3. .
In addition, it is preferable that the polymer has less impurities such as halogen and metal, so that the coating property as an upper layer film and the uniform solubility in an alkali developer can be further improved. Examples of polymer purification methods include chemical purification methods such as washing with water and liquid-liquid extraction, and combinations of these chemical purification methods with physical purification methods such as ultrafiltration and centrifugation. it can. In this invention, a polymer can be used individually or in mixture of 2 or more types.

The upper layer film-forming resin composition for immersion of the present invention is obtained by dissolving the above polymer as a resin component in an alcohol solvent. As the alcohol solvent, a solvent that dissolves the polymer and does not deteriorate the lithography performance by causing intermixing with the photoresist film when applied onto the photoresist film can be used.
Examples of such an alcohol solvent include a solvent containing a monohydric alcohol. For example, methanol, ethanol, 1-propanol, isopropanol, n-propanol, 1-butanol, 2-butanol, tert-butanol, 1-pentanol, 2-pentanol, 3-pentanol, n-hexanol, cyclohexanol, 2-methyl-2-butanol, 3-methyl-2-butanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-methyl-1-pentanol, 2-methyl-2-pentanol, 2- Methyl-3-pentanol, 3-methyl-1-pentanol, 3-methyl-2-pentanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2-pen C1-C6 monohydric alcohols such as butanol, 2,2-dimethyl-3-pentanol, 2,3-dimethyl -3-pentanol, 2,4-dimethyl-3-pentanol, 4,4-dimethyl-2-pentanol, 3-ethyl-3-pentanol, 1-heptanol, 2-heptanol, 3-heptanol, 2 Monovalent alcohols having 7 carbon atoms such as methyl-2-hexanol, 2-methyl-3-hexanol, 5-methyl-1-hexanol, 5-methyl-2-hexanol; 2-ethyl-1-hexanol, 4- Carbon such as methyl-3-heptanol, 6-methyl-2-heptanol, 1-octanol, 2-octanol, 3-octanol, 2-propyl-1-pentanol, 2,4,4-trimethyl-1-pentanol Monohydric alcohol of number 8; 2,6-dimethyl-4-heptanol, 3-ethyl-2,2-dimethyl-pentanol, 1-nonanol C9 monohydric alcohols such as 2-nonanol and 3,5,5-trimethyl-1-hexanol; 1-decanol, 2-decanol, 4-decanol, 3,7-dimethyl-1-octanol, 3,7 Examples thereof include monohydric alcohols having 10 carbon atoms such as dimethyl-3-octanol. These alcohols can be used alone or in combination of two or more.
Among these alcohols, 1-butanol, 3-methyl-2-pentanol and 4-methyl-2-pentanol are preferable because they have a boiling point and a flash point suitable for the use environment and the working environment.

In addition, when the upper layer film is applied on the photoresist film, another solvent can be mixed for the purpose of adjusting the coating property. Other solvents have the effect of uniformly coating the upper layer film without eroding the photoresist film.
Other solvents include polyhydric alcohols such as ethylene glycol and propylene glycol; cyclic ethers such as tetrahydrofuran and dioxane; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol monomethyl ether Alkyl ethers of polyhydric alcohols such as diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether; ethylene glycol ethyl ether acetate, diethylene glycol ethyl Alkyl ether acetates of polyhydric alcohols such as ether acetate, propylene glycol ethyl ether acetate, and propylene glycol monomethyl ether acetate; aromatic hydrocarbons such as toluene and xylene; acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, 4-hydroxy- Ketones such as 4-methyl-2-pentanone and diacetone alcohol; ethyl acetate, butyl acetate, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl 2-hydroxy-2-methylpropionate , Ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutanoate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, Kishipuropion acid ethyl esters such as methyl 3-ethoxypropionate, and water. Among these, cyclic ethers, polyhydric alcohol alkyl ethers, polyhydric alcohol alkyl ether acetates, ketones, esters, and water are preferable.

  The blending ratio of the other solvent is 30% by weight or less, preferably 20% by weight or less in the solvent component. If it exceeds 30% by weight, the photoresist film is eroded, causing problems such as intermixing with the upper layer film, and the resolution performance of the photoresist is significantly deteriorated.

In the upper layer film-forming resin composition for immersion according to the present invention, a surfactant can also be blended for the purpose of improving coating properties, antifoaming properties, leveling properties and the like.
Surfactants include, for example, BM-1000, BM-1100 (above, manufactured by BM Chemie), MegaFuck F142D, F172, F173, F183 (above, manufactured by Dainippon Ink and Chemicals), Florard FC-135, FC-170C, FC-430, FC-431 (above, manufactured by Sumitomo 3M), Surflon S-112, S-113, S-131, S-141, Commercially available under trade names such as S-145 (above, manufactured by Asahi Glass Co., Ltd.), SH-28PA, i-190, i-193, SZ-6032, SF-8428 (above, made by Toray Dow Corning Silicone Co., Ltd.) Fluorosurfactant that has been used can be used.
The compounding amount of these surfactants is preferably 5 parts by weight or less with respect to 100 parts by weight of the polymer.

The liquid film forming resin composition for immersion according to the present invention is used for forming an upper film on a photoresist film formed on a silicon wafer. The photoresist used is not particularly limited, and can be selected in a timely manner according to the purpose of use of the resist. Examples of the resist include a chemically amplified positive type or negative type resist containing an acid generator.
An upper film can be formed by applying and baking the upper film forming resin composition of the present invention on a photoresist film. The upper layer film is formed to protect the photoresist film and to prevent contamination of the lens of the projection exposure apparatus caused by elution of components contained in the photoresist film into the immersion liquid.
The upper layer film obtained from the upper layer film-forming resin composition of the present invention comprises at least one saturated hydrocarbon selected from trans-decahydronaphthalene, 1,1-bicyclohexyl, and exo-tetrahydrodicyclopentadiene as an immersion liquid. When a compound is used, it has a molecular structure in which the contact angle with the liquid is 65 ° or more and less than 90 °. The refractive index at 193 nm is 1.6 or more and 1.8 or less.
As the thickness of the upper layer film is closer to an odd multiple of λ / 4m (λ is the wavelength of radiation and m is the refractive index of the upper layer film), the reflection suppressing effect at the upper interface of the resist film is increased. For this reason, it is preferable that the thickness of the upper layer film be close to this value.
The photoresist film on which the upper layer film is formed is irradiated with radiation through the immersion liquid and then developed to form a resist pattern.
Radiation used for immersion exposure is selected from various types of radiation such as visible light; ultraviolet rays such as g-rays and i-rays; far ultraviolet rays such as excimer lasers; X-rays such as synchrotron radiation; and charged particle beams such as electron beams. Can be used. In particular, an ArF excimer laser (wavelength 193 nm) or a KrF excimer laser (wavelength 248 nm) is preferable.

Polymers (A-1) and (A-2) for the liquid immersion upper layer film were synthesized by the method shown below. In addition, Mw and Mn of each polymer are the Tosoh Co., Ltd. high-speed GPC apparatus (model "HLC-8120"), Tosoh Co., Ltd. GPC column (brand name "G2000H _XL "; 2 pieces, "G3000H _XL ") ”; One,“ G4000H _XL ”; one), gel permeation chromatography (GPC) using monodisperse polystyrene as a standard under flow rate of 1.0 ml / min, elution solvent tetrahydrofuran, and column temperature of 40 ° C. It was measured by. Moreover, the ratio of each repeating unit in a polymer was measured by ¹³ C NMR.
The monomer used for each polymer synthesis is represented below as formulas (M-1) to (M-4).

Example 1
3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl acrylate (M-1) 8.36 g, 2, 2,2-trifluoroethyl acrylate (M-2) 4.73 g, 2-acrylamido-2-methylpropanesulfonic acid (M-3) 1.67 g, 2-methacrylic acid-S- (2-tetrahydropyran-2 -Yl) 5.24 g of ester (M-4) and 60 g of 2-propanol were put into a flask and heated to 70 ° C. to obtain a uniform solution. Thereafter, the temperature of the solution was lowered to 65 ° C., and 0.8 g of AIBN (azoisobutyronitrile) was added. Thereafter, the mixture was reacted at 65 ° C. for 6 hours. After the reaction, the reaction mixture was added to 300 g of hexane, and the solvent was removed by decantation to obtain a white solid. The obtained solid was vacuum-dried at 60 ° C. for 4 hours to obtain a polymer for liquid immersion upper layer film (A-1) (yield 60% by weight).
As a result of ¹³ C-NMR measurement, the obtained polymer (A-1) is a repeating unit derived from the monomer (M-1) / a repeating unit derived from the same (M-2) / the same (M-3). It was a polymer composed of the repeating unit derived from / the repeating unit derived from (M-4) = 20/35/10/35 (molar ratio). Moreover, it was Mw17000 and Mw / Mn1.7.

Example 2
3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl acrylate (M-1) 8.27 g, 2, 2.67 g of 2,2-trifluoroethyl acrylate (M-2), 1.65 g of 2-acrylamido-2-methylpropanesulfonic acid (M-3), 2-methacrylic acid-S- (2-tetrahydrofuran-2-) Yl) 7.41 g of ester (M-4) and 60 g of 2-propanol were put into a flask and heated to 65 ° C. to obtain a uniform solution. Thereafter, 0.8 g of AIBN (azoisobutyronitrile) was added. Thereafter, the mixture was reacted at 65 ° C. for 6 hours. After the reaction, the reaction mixture was added to 300 g of hexane, and the solvent was removed by decantation to obtain a white solid. The obtained solid was vacuum-dried at 60 ° C. for 4 hours to obtain a polymer for liquid immersion upper layer film (A-2) (yield: 58% by weight).
As a result of ¹³ C-NMR measurement, the obtained polymer (A-2) is a repeating unit derived from the monomer (M-1) / a repeating unit derived from the same (M-2) / the same (M-3). It was a polymer composed of the repeating unit derived from / the repeating unit derived from (M-4) = 20/20/10/50 (molar ratio). Moreover, it was Mw16000 and Mw / Mn1.8.

Example 3
5 g of the polymer (A-1) was dissolved in 95 g of 4-methyl-2-pentanol to obtain a liquid immersion upper layer film-forming resin composition (B-1).
The resin composition (B-1) is spin-coated (2500 rpm) on a silicon wafer previously coated with ArF resist AR1244J (manufactured by JSR), and baked at 150 ° C. for 5 minutes to obtain an upper layer film (C-1). It was.
The contact angle, refractive index at 193 nm, and developability of the upper layer film (C-1) were measured. The results are shown in Table 1.
The contact angle was measured using DSA-10 manufactured by KRUS for the contact angle with trans-decahydronaphthalene, 1,1-bicyclohexyl, and exo-tetrahydrodicyclopentadiene. 0.05 ml of liquid was dropped on the upper layer film (C-1), the contact angle 3 to 10 seconds after dropping was measured every other second, and the average value was obtained as the contact angle.
The refractive index at 193 nm was measured at 25 ° C. using a spectroscopic ellipsometer.
As for developability, when the silicon wafer coated with the upper layer film (C-1) was immersed in a 2.38% TMAH (tetramethylammonium hydroxide) aqueous solution and the upper layer film was completely removed, the developability was ○, and was not removed. In this case, the developability was evaluated as x.

Example 4
5 g of the polymer (A-2) was dissolved in 95 g of 4-methyl-2-pentanol to obtain a liquid immersion upper layer film-forming resin composition (B-2).
An upper layer film (C-2) was obtained by the same method as in Example 3 except that this liquid immersion upper layer film-forming resin composition (B-2) was used. The contact angle of 2), the refractive index at 193 nm, and developability were measured. The results are shown in Table 1.

Comparative Example 1
6. 10.0 g of cyclohexyl acrylate, 2.41 g of 2-acrylamido-2-methylpropanesulfonic acid (M-3), 2-methacrylic acid-S- (2-tetrahydropyran-2-yl) ester (M-4) 588 g and 2-propanol 60 g were put into a flask and heated to 65 ° C. to obtain a uniform solution. Thereafter, 0.8 g of AIBN (azoisobutyronitrile) was added. Thereafter, the mixture was reacted at 65 ° C. for 6 hours. After the reaction, the reaction mixture was added to 300 g of hexane, and the solvent was removed by decantation to obtain a white solid. The obtained solid was vacuum-dried at 60 ° C. for 4 hours to obtain a polymer (H-1) (yield 55% by weight).
As a result of ¹³ C-NMR measurement, the obtained polymer (H-1) was a repeating unit derived from cyclohexyl acrylate / a repeating unit derived from the monomer (M-3) / a repeating unit derived from the same (M-4). = 55/10/35 (molar ratio). Moreover, it was Mw18000 and Mw / Mn1.9.
5 g of the polymer (H-1) was dissolved in 95 g of 4-methyl-2-pentanol to obtain a liquid immersion upper layer film-forming resin composition. An upper film (D-1) was obtained by the same method as in Example 3 except that this liquid immersion upper film forming resin composition was used, and the contact angle of the upper film (D-1) by the same method as in Example 3. The refractive index and developability at 193 nm were measured. The results are shown in Table 1.

Comparative Example 2
3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl acrylate (M-1) 9.296 g, 2, 10.518 g of 2,2-trifluoroethyl acrylate (M-2), 1.71 g of 2-acrylamido-2-methylmethacrylic acid and 60 g of 2-propanol were put into a flask and heated to 65 ° C. to obtain a uniform solution. did. Thereafter, 0.8 g of AIBN (azoisobutyronitrile) was added. Thereafter, the mixture was reacted at 65 ° C. for 6 hours. After the reaction, the reaction mixture was added to 300 g of hexane, and the solvent was removed by decantation to obtain a white solid. The obtained solid was vacuum-dried at 60 ° C. for 4 hours to obtain a polymer (H-2) (yield 57% by weight).
As a result of ¹³ C-NMR measurement, the obtained polymer (H-2) was found to have a repeating unit derived from the monomer (M-1) / a repeating unit derived from the same (M-2) / 2-acrylamide-2- It was a polymer composed of repeating units derived from methyl methacrylic acid = 20/70/10 (molar ratio). Moreover, it was Mw15000 and Mw / Mn1.8.
5 g of the polymer (H-2) was dissolved in 95 g of 4-methyl-2-pentanol to obtain a liquid immersion upper layer film-forming resin composition. An upper layer film (D-2) was obtained by the same method as in Example 3 except that this liquid immersion upper layer film-forming resin composition was used, and the contact angle of the upper layer film (D-2) by the same method as in Example 3. The refractive index and developability at 193 nm were measured. The results are shown in Table 1.

  Since the polymer of the present invention described above has oil repellency and little liquid remains for immersion on the upper film during high-speed scanning, it can form an upper film having a sufficiently high refractive index corresponding to high NA exposure. At the time of immersion exposure, even if scanning exposure is performed at a high speed, the “stain” is difficult to remain because the liquid for immersion is good. In addition, the upper layer film can protect the lens and the resist during immersion exposure, and can form a resist pattern excellent in resolution, developability, and the like. Therefore, it can be used very suitably for the manufacture of semiconductor devices that are expected to be further miniaturized in the future.

Claims (6)

  A film having a contact angle with an immersion liquid composed of a saturated hydrocarbon compound of 65 ° or more and less than 90 ° and a refractive index at 193 nm of 1.6 or more and 1.8 or less can be formed. A polymer for a liquid immersion upper layer film having a weight average molecular weight of 2,000 to 100,000 as measured by a permeation chromatography method.   The liquid according to claim 1, wherein the saturated hydrocarbon compound is at least one saturated hydrocarbon compound selected from trans-decahydronaphthalene, 1,1-bicyclohexyl, and exo-tetrahydrodicyclopentadiene. Polymer for immersion layer film.   The liquid according to claim 1 or 2, wherein the polymer contains a repeating unit having a group containing a fluorine atom in its side chain and a repeating unit having a group containing a sulfur atom in its side chain. Polymer for immersion layer film. The polymer for an immersion upper layer film according to claim 3, wherein the repeating unit having a group containing a fluorine atom in its side chain is represented by the following formula (1).

(R ¹ , R ² , and R ³ each independently represents a hydrogen atom or a methyl group, and Rf represents a monovalent fluorinated hydrocarbon group in which at least some of the hydrogen atoms are substituted with fluorine atoms.) The polymer for an immersion upper layer film according to claim 3, wherein the repeating unit having a group containing a sulfur atom in its side chain is represented by the following formula (2).

(R ⁴ , R ⁵ and R ⁶ represent a hydrogen atom or a methyl group, and Rs represents a monovalent organic group containing a sulfur atom.) An immersion upper layer film-forming resin composition for forming an upper layer film to be coated on a photoresist film subjected to immersion exposure,
The resin composition is obtained by dissolving a resin in an alcohol solvent, and the resin is the polymer according to any one of claims 1 to 5. .