JP2008209799A - Photoresist pattern forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoresist pattern forming method using a radiation-sensitive resin composition and an upper layer film forming composition each having sufficient transmittance at an exposure wavelength, particularly at 248 nm (KrF) and 193 nm (ArF). <P>SOLUTION: The photoresist pattern forming method includes: forming a photoresist film on a substrate by applying the radiation-sensitive resin composition containing a resin containing >60 mol% of a monomer which becomes alkali-soluble under the action of an acid and a radiation-sensitive acid generator; forming an upper layer film on the photoresist film by applying the upper layer film forming composition containing an alkali-soluble resin containing at least one of specific monomers; and obtaining a resist pattern by disposing a liquid immersion medium between the upper layer film and a lens, irradiating the photoresist film and the upper layer film with exposure light via the liquid immersion medium and a mask having a predetermined pattern, and performing development. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention protects a photoresist film during immersion exposure used for lithography miniaturization, and forms an upper film that protects a lens of a projection exposure apparatus by suppressing elution of components of the photoresist film. The present invention relates to a method for forming a photoresist pattern using a composition for forming an upper layer film useful for the present invention.

  When manufacturing a semiconductor element or the like, a reticle pattern as a photomask is applied to each shot region on a wafer coated with a photoresist film (hereinafter sometimes referred to as “photoresist”) via a projection optical system. A stepper type or step-and-scan type projection exposure apparatus for transferring is used. The resolution of the projection optical system provided in 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.

In addition, when performing exposure, the depth of focus is important as well as the resolution. The resolution R and the depth of focus δ are each expressed by the following equations. In order to obtain the same resolution R, it is possible to obtain a large depth of focus δ by using radiation having a short wavelength.
R = k1 · λ / NA (i)
δ = k2 · λ / NA2 (ii)
(Where λ is the exposure wavelength, NA is the numerical aperture of the projection optical system, and k1 and k2 are both process coefficients)

A photoresist film is formed on the exposed wafer surface, and the pattern is transferred to the photoresist film. In the conventional projection exposure apparatus, the space in which the wafer is placed is filled with air or nitrogen. At this time, when the space between the wafer and the lens of the projection exposure apparatus is filled with a medium having a refractive index n, the resolution R and the depth of focus δ are expressed by the following equations.
R = k1 · (λ / n) / NA (iii)
δ = k2 · nλ / NA2 (iv)

  For example, when water is used as the medium in the ArF process, when the refractive index n = 1.44 in water of light having a wavelength of 193 nm is used, the resolution R is compared with that during exposure using air or nitrogen as a medium. 69.4% (R = k1 · (λ / 1.44) / NA), and the focal depth is 144% (δ = k2 · 1.44λ / NA2).

  In this way, the projection exposure method capable of shortening the wavelength of radiation for exposure and transferring a finer pattern is called immersion exposure, which is indispensable for lithography miniaturization, particularly lithography of several tens of nanometers. The projection exposure apparatus is also known (refer to Patent Document 1).

  In the immersion exposure method using water as a medium for immersion exposure, the photoresist film formed on the wafer and the lens of the projection exposure apparatus are in contact with water, respectively. Therefore, water may penetrate into the photoresist film and the resolution of the photoresist may be reduced. In addition, the lens of the projection exposure apparatus may contaminate the lens surface due to elution of components constituting the photoresist into water.

  For this reason, there is a method of forming an upper layer film (protective film) on the photoresist film for the purpose of blocking the photoresist film from a medium such as water. However, the upper layer film can be formed on the photoresist film with (1) sufficient transparency to the wavelength of radiation, and (2) almost no intermixing with the photoresist film. (3) It is possible to maintain a stable coating without leaching into a medium such as water at the time of immersion exposure, and (4) it is easily dissolved in an alkaline solution or the like as a developer. Is required. Note that Patent Documents 2 and 3 are disclosed as related prior art documents.

Japanese Patent Laid-Open No. 11-176727 JP 2005-264131 A JP 2006-64711 A

  According to the resist pattern forming method disclosed in Patent Documents 2 and 3, an intermixing layer is generated more than necessary in the step of applying the upper layer film depending on the constituent components of the resist film, and as a result, peeling with a developer is performed. Later, the desired resist film thickness cannot be maintained, and etching defects may occur in the subsequent dry etching process. Therefore, it is necessary to consider the incompatibility between the constituent components of the resist film protected by the upper layer film and the applied upper layer film component.

  The present invention has been made to address such problems, and has sufficient transparency at exposure wavelengths, particularly 248 nm (KrF) and 193 nm (ArF), and a photoresist film and an upper layer applied thereon. It is an object of the present invention to provide a method for forming a photoresist pattern using a radiation sensitive resin composition that hardly causes intermixing with a film and an upper film forming composition.

  The present inventors include a step of applying a resin containing an acid dissociable group and a radiation-sensitive resin composition on a substrate to form a photoresist film, a step of forming an upper layer film on the photoresist film, It has been found that the above problem can be achieved by disposing an immersion medium between the upper layer film and the lens, irradiating the photoresist film and the upper layer film with exposure light, and then developing. That is, according to the present invention, the following photoresist pattern forming method is provided.

  [1] A radiation-sensitive resin composition containing a resin (A) containing a repeating unit containing an acid-dissociable group in an amount exceeding 60 mol% and a radiation-sensitive acid generator (B) on the substrate. And a step of forming a photoresist film by applying to the photoresist film, and applying an upper layer film-forming composition containing an alcohol having 4 to 10 carbon atoms in a mass ratio of 50% by mass or less to the photoresist film. A step of forming an upper layer film, an immersion medium is disposed between the upper layer film and the lens, and the photoresist film and the upper layer film are exposed through the immersion medium and the mask having a predetermined pattern. Irradiating light and then developing to obtain a resist pattern.

（前記一般式（１−１）、（１−２）、（１−３）、（１−４）及び（１−５）中、Ｒ^１は水素、メチル基、又はトリフルオロメチル基を示し、Ｒ^２、Ｒ^３、Ｒ^４は互いに独立に、単結合、メチレン、炭素数２〜６の直鎖状若しくは分岐状のアルキレン基、又は炭素数４〜１２の脂環式のアルキレン基を示し、Ｒ^５は少なくとも一つの水素原子がフッ素原子で置換された炭素数１〜１０の直鎖状若しくは分岐状のアルキル基、又は炭素数３〜１０の脂環式のアルキル基を示し、Ｒ^６は単結合、メチレン、炭素数２〜６の直鎖状若しくは分岐状のアルキレン基、又は一般式、Ｃ（Ｏ）ＸＲ^８で表される基を示し、Ｘは酸素、硫黄、又はＮＨ基を示し、Ｒ^８はメチレン、炭素数２〜６の直鎖状又は分岐状のアルキレン基を示し、Ｒ^７は少なくとも一つの水素原子がフッ素原子で置換された炭素数１〜１２の直鎖状若しくは分岐状のアルキル基、又は少なくとも一つの水素原子がフッ素原子で置換された脂環式構造を有する炭素数１〜１２のアルキル基を示す） [2] The above [1] description, wherein the upper film-forming composition contains a resin (a) containing at least one repeating unit represented by the following general formulas (1-1) to (1-5). Resist pattern forming method.

(In the general formulas (1-1), (1-2), (1-3), (1-4) and (1-5), R ¹ represents hydrogen, a methyl group, or a trifluoromethyl group. , R ² , R ³ and R ⁴ each independently represent a single bond, methylene, a linear or branched alkylene group having 2 to 6 carbon atoms, or an alicyclic alkylene group having 4 to 12 carbon atoms. , R ⁵ represents a linear or branched alkyl group having 1 to 10 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom, or an alicyclic alkyl group having 3 to 10 carbon atoms, and R ⁶ is a single bond, a methylene, a linear or branched alkylene group having 2 to 6 carbon atoms, or the general formula, a group represented by C (O) XR ^8, X is oxygen, sulfur, or NH group shown, R ⁸ represents a methylene, a linear or branched alkylene group having 2 to 6 carbon atoms, R ⁷ is small C1-C12 linear or branched alkyl group in which at least one hydrogen atom is substituted with a fluorine atom, or carbon number having an alicyclic structure in which at least one hydrogen atom is substituted with a fluorine atom 1 to 12 alkyl groups)

  [3] The resist pattern forming method according to [1] or [2], wherein the resin (A) contained in the radiation-sensitive resin composition contains a repeating unit containing a lactone structure.

  The photoresist film and the upper layer film formed with the radiation-sensitive composition and the upper layer film-forming composition of the present invention have sufficient transparency at exposure wavelengths, particularly 248 nm (KrF) and 193 nm (ArF), A photoresist pattern can be formed with almost no intermixing between the respective films.

  Hereinafter, the best embodiment of the present invention will be described, but the present invention is not limited to the following embodiment, and changes, modifications, and improvements can be added without departing from the scope of the invention. .

[1] Radiation-sensitive composition The radiation-sensitive resin composition of the present invention comprises a resin (A) containing more than 60 mol% of a repeating unit that becomes alkali-soluble by the action of an acid and a radiation-sensitive acid generator ( A composition containing B).

[1-1] Resin (A)
The resin (A) contains a repeating unit (1) that becomes alkali-soluble by the action of an acid represented by the following general formula (1).

（前記一般式（１）中、Ｒ^１は相互に独立に、炭素数４〜２０の一価の脂環式炭化水素基若しくはその誘導体、又は炭素数１〜４の直鎖状若しくは分岐状のアルキル基を表し、かつ、Ｒ^１の少なくとも１つが上記脂環式炭化水素基若しくはその誘導体であり、３つのＲ^１のうち何れか２つのＲ^１が相互に結合して、それぞれが結合している炭素原子と共に炭素数４〜２０の２価の脂環式炭化水素基若しくはその誘導体を形成し、残りのＲ^１が炭素数１〜４の直鎖状若しくは分岐状のアルキル基、又は炭素数４〜２０の一価の脂環式炭化水素基若しくはその誘導体を表す）

(In the general formula (1), R ¹ are independently of each other a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof, or a linear or branched chain having 1 to 4 carbon atoms. represents an alkyl group, and at least one of R ¹ is a alicyclic hydrocarbon group or its derivative, three with any two of R ¹ of R ¹ are bonded to each other, are bonded to each other A divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof together with the carbon atom, and the remaining R ¹ is a linear or branched alkyl group having 1 to 4 carbon atoms, or carbon number 4-20 monovalent alicyclic hydrocarbon groups or derivatives thereof)

  Examples of the monomer for constituting the repeating unit (1) include (meth) acrylic acid 2-methyladamantyl-2-yl ester, (meth) acrylic acid 2-ethyladamantyl-2-yl ester, (Meth) acrylic acid-2-methylbicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid-2-ethylbicyclo [2.2.1] hept-2-yl ester, (meth) Acrylic acid 1- (bicyclo [2.2.1] hept-2-yl) -1-methylethyl ester, (meth) acrylic acid 1- (adamantan-1-yl) -1-methylethyl ester, (meth) 1-methyl-1-cyclopentyl acrylate, 1-ethyl-1-cyclopentyl (meth) acrylate, 1-methyl-1-cyclohexyl (meth) acrylate Glycol ester, (meth) acrylic acid 1-ethyl-1-cyclohexyl ester, and the like are preferable. In addition, the polymer for radiation sensitive resin compositions of this invention may contain the 2 or more types of said repeating unit (1).

Moreover, the radiation sensitive resin composition of this invention may contain the repeating unit (2) which has a lactone skeleton as another repeating unit. As a monomer for constituting the repeating unit (2), for example, (meth) acrylic acid-5-oxo-4-oxa-tricyclo [4.2.1.0 ^3,7 ] non-2-yl Ester, (meth) acrylic acid-5-oxo-4-oxa-tricyclo [5.2.1.0 ^3,8 ] dec-2-yl ester, (meth) acrylic acid-6-oxo-7-oxa- Bicyclo [3.2.1] oct-2-yl ester, (meth) acrylic acid-7-oxo-8-oxa-bicyclo [3.3.1] oct-2-yl ester, (meth) acrylic acid- 2-oxotetrahydropyran-4-yl ester, (meth) acrylic acid-5-oxotetrahydrofuran-3-yl ester, (meth) acrylic acid-2-oxotetrahydrofuran-3-yl ester, (meth) acrylic ester Examples thereof include oxalic acid-2-oxotetrahydrofuran-3-yl ester and (meth) acrylic acid-5-oxotetrahydrofuran-2-ylmethyl ester.

As other repeating units, meth) acrylic acid-bicyclo [2.2.1] heptyl ester, (meth) acrylic acid-cyclohexyl ester, (meth) acrylic acid-bicyclo [4.4.0] decanyl ester , (Meth) acrylic acid-bicyclo [2.2.2] octyl ester, (meth) acrylic acid-tricyclo [5.2.1.0 ^2,6 ] decanyl ester, (meth) acrylic acid-tetracyclo [6] 2.1.1 ^3,6 . 0 ^2,7 ] dodecanyl ester, (meth) acrylic acid-tricyclo [3.3.1.1 ^3,7 ] decanyl ester, and the like.

(Meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-3-propyl) ester, (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl) -2-hydroxy-5-pentyl) ester, (meth) acrylic acid 2-{[5- (1 ′, 1 ′, 1′-trifluoro-2′-trifluoromethyl-2′-hydroxy) propyl] bicyclo [2.2.1] heptyl} ester, (meth) acrylic acid 3-{[8- (1 ′, 1 ′, 1′-trifluoro-2′-trifluoromethyl-2′-hydroxy) propyl] tetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] dodecyl} ester and the like.

  (Meth) acrylic acid 3-hydroxyadamantan-1-ylmethyl ester, (meth) acrylic acid 3,5-dihydroxyadamantan-1-ylmethyl ester, (meth) acrylic acid 3-hydroxy-5-methyladamantan-1-yl Ester, (meth) acrylic acid 3,5-dihydroxy-7-methyladamantan-1-yl ester, (meth) acrylic acid 3-hydroxy-5,7-dimethyladamantan-1-yl ester, (meth) acrylic acid 3 -Hydroxy-5,7-dimethyladamantan-1-ylmethyl ester and the like.

  (Meth) acrylic acid adamantylmethyl, (meth) acrylic acid carboxynorbornyl, (meth) acrylic acid carboxytricyclodecanyl, (meth) acrylic acid methyl, (meth) acrylic acid ethyl, (meth) acrylic acid n- Propyl, n-butyl (meth) acrylate, 2-methylpropyl (meth) acrylate, 1-methylpropyl (meth) acrylate, t-butyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (Meth) acrylic acid 2-hydroxypropyl, (meth) acrylic acid 3-hydroxypropyl, (meth) acrylic acid cyclopentyl, (meth) acrylic acid cyclohexyl, (meth) acrylic acid 4-methoxycyclohexyl, and the like.

  1,2-adamantanediol di (meth) acrylate, 1,3-adamantanediol di (meth) acrylate, 1,4-adamantanediol di (meth) acrylate, tricyclodecanyl dimethylol di (meth) acrylate, etc., methylene Glycol di (meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 2,5-dimethyl-2,5-hexanediol di (meth) ) Acrylate, 1,8-octanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,4-bis (2-hydroxypropyl) benzenedi (meth) acrylate, 1,3-bis ( 2-hydroxypropyl) benzenedi Meth) acrylate.

  When resin (A) contains a repeating unit (1), it is preferable that the content rate contains more than 60 mol% with respect to all the repeating units of the said polymer. There exists a possibility that the resolution performance as a resist may fall that the content rate of a repeating unit (1) is 60 mol% or less.

  Resin (A) uses, for example, a radical polymerization initiator such as hydroperoxides, dialkyl peroxides, diacyl peroxides, and azo compounds, and in the presence of a chain transfer agent, if necessary, in a suitable solvent. It can be produced by polymerizing a polymerizable unsaturated monomer for constituting each repeating unit.

  Examples of the solvent used for the polymerization include alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, cyclohexane, cycloheptane, cyclooctane, decalin, norbornane. Cycloalkanes such as benzene, toluene, xylene, ethylbenzene, cumene and other aromatic hydrocarbons, chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, halogenated hydrocarbons such as chlorobenzene, ethyl acetate, Saturated carboxylic acid esters such as n-butyl acetate, i-butyl acetate and methyl propionate, ketones such as acetone, 2-butanone, 4-methyl-2-pentanone and 2-heptanone, tetrahydrofuran, dimethoxyethanes, di Ethers such as ethoxyethanes It can be mentioned. In addition, these solvents can be used individually or in mixture of 2 or more types. Moreover, the reaction temperature in the said superposition | polymerization is 40-150 degreeC normally, Preferably it is 50-120 degreeC, and reaction time is 1-48 hours normally, Preferably it is 1-24 hours.

  The molecular weight of the polymer for radiation-sensitive resin composition of the present invention is not particularly limited, but the polystyrene-reduced weight average molecular weight (hereinafter sometimes referred to as “Mw”) by gel permeation chromatography (GPC) is 1. It is good that it is 1,000-100,000, Preferably it is 1,000-30,000, More preferably, it is 1,000-20,000. When the Mw of the polymer is less than 1,000, when the resist film is formed, the heat resistance may be lowered. On the other hand, if it exceeds 100,000, the developability of the resist film may decrease. The ratio (Mw / Mn) of the polymer Mw to the polystyrene-equivalent number average molecular weight (hereinafter sometimes referred to as “Mn”) by gel permeation chromatography (GPC) is usually 1 to 5, preferably Is 1-3.

  In addition, the polymer for radiation-sensitive resin composition of the present invention preferably has a low content of impurities such as halogen and metal, and if the impurities are reduced, the sensitivity, resolution, process stability, pattern of the resist film to be formed are reduced. The shape and the like can be further improved. Examples of the purification method of the polymer 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. Can do. In addition, the polymer for radiation sensitive resin compositions of this invention can be used individually or in mixture of 2 or more types.

[1-2] Radiation sensitive acid generator (B)
The radiation-sensitive acid generator (hereinafter also referred to as “acid generator (B)”) according to the present invention is a compound that generates an acid in the coating film by irradiating the photoresist film with radiation (exposure). is there. The acid generated from the acid generator (B) by exposure to the resin (A) containing the repeating unit (1) having a structure that expresses alkali solubility by the action of an acid acts, whereby the repeating unit (1) The acid dissociable group is dissociated (the protecting group is eliminated). As a result, the exposed portion of the photoresist film becomes readily soluble in an alkali developer, and a positive resist pattern is formed. Examples of the acid generator (B) include the following substances.

  For example, triphenylsulfonium trifluoromethanesulfonate, tri-tert-butylphenylsulfonium trifluoromethanesulfonate, 4-cyclohexylphenyl-diphenylsulfonium trifluoromethanesulfonate, 4-methanesulfonylphenyl-diphenylsulfonium trifluoromethanesulfonate, 1- (3,5- Dimethyl-4-hydroxyphenyl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-n-butoxynaphthyl) tetrahydrothiophenium trifluoromethanesulfonate, triphenylsulfonium perfluoro-n-butanesulfonate, tri-tert-butylphenyl Sulfonium perfluoro-n-butanesulfonate, 4-cyclohexylpheny -Diphenylsulfonium perfluoro-n-butanesulfonate, 4-methanesulfonylphenyl-diphenylsulfonium perfluoro-n-butanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium perfluoro-n- Butanesulfonate, 1- (4-n-butoxynaphthyl) tetrahydrothiophenium perfluoro-n-butanesulfonate, and the like.

  Triphenylsulfonium perfluoro-n-octane sulfonate, tri-tert-butylphenylsulfonium perfluoro-n-octane sulfonate, 4-cyclohexylphenyl-diphenylsulfonium perfluoro-n-octane sulfonate, 4-methanesulfonylphenyl-diphenylsulfonium per Fluoro-n-octanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (4-n-butoxynaphthyl) tetrahydrothiophenium perfluoro- n-octanesulfonate, triphenylsulfonium 2- (bicyclo [2.2.1] hepta-2'-yl) -1,1,2,2-tetrafluoroethanesulfonate, tri -Tert-butylphenylsulfonium 2- (bicyclo [2.2.1] hepta-2'-yl) -1,1,2,2-tetrafluoroethanesulfonate, 4-cyclohexylphenyl-diphenylsulfonium 2- (bicyclo [ 2.2.1] Hepta-2′-yl) -1,1,2,2-tetrafluoroethanesulfonate, 4-methanesulfonylphenyl-diphenylsulfonium 2- (bicyclo [2.2.1] hepta-2 ′ -Yl) -1,1,2,2-tetrafluoroethanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium 2- (bicyclo [2.2.1] hepta-2 ' -Yl) -1,1,2,2-tetrafluoroethanesulfonate, 1- (4-n-butoxynaphthyl) tetrahydrothiophenium 2- (bicyclo [2.2.1] hepta-2'-yl) -1,1,2,2-tetrafluoroethanesulfonate and the like.

  Triphenylsulfonium 2- (bicyclo [2.2.1] hepta-2'-yl) -1,1-difluoroethanesulfonate, tri-tert-butylphenylsulfonium 2- (bicyclo [2.2.1] hepta-2 '-Yl) -1,1-difluoroethanesulfonate, 4-cyclohexylphenyl-diphenylsulfonium 2- (bicyclo [2.2.1] hepta-2'-yl) -1,1-difluoroethanesulfonate, 4-methanesulfonylphenyl -Diphenylsulfonium 2- (bicyclo [2.2.1] hepta-2'-yl) -1,1-difluoroethanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium 2- ( Bicyclo [2.2.1] hepta-2'-yl) -1,1-difluoroethanesulfur 1- (4-n-butoxynaphthyl) tetrahydrothiophenium 2- (bicyclo [2.2.1] hepta-2'-yl) -1,1-difluoroethanesulfonate, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium Nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, diphenyliodonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate, bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate, bis (4-t-butylphenyl) iodonium perfluoro-n-octa Sulfonate, bis (4-t- butylphenyl) iodonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate like.

  Trifluoromethanesulfonylbicyclo [2.2.1] hept-5-ene-2,3-dicarbodiimide, nonafluoro-n-butanesulfonylbicyclo [2.2.1] hept-5-ene-2,3-dicarbodiimide Perfluoro-n-octanesulfonylbicyclo [2.2.1] hept-5-ene-2,3-dicarbodiimide, 2-bicyclo [2.2.1] hept-2-yl-1,1,2 , 2-tetrafluoroethanesulfonylbicyclo [2.2.1] hept-5-ene-2,3-dicarbodiimide, N- (trifluoromethanesulfonyloxy) succinimide, N- (nonafluoro-n-butanesulfonyloxy) succinimide N- (perfluoro-n-octanesulfonyloxy) succinimide, N- (2-bicyclo [2.2 1] Hept-2-yl-1,1,2,2-tetrafluoroethanesulfonyloxy) succinimide, 1,8-naphthalenedicarboxylic imide trifluoromethanesulfonate, and the following formulas (B1-1) to (B1- 8).

  An acid generator (B) can be used individually or in mixture of 2 or more types.

  In the present invention, the total amount of the acid generator (B) used is based on 100 parts by mass of the resin (A) from the viewpoint of resist sensitivity, developability, and suppression of elution from the composition into the immersion liquid. The amount is usually 0.1 to 20 parts by mass, preferably 0.5 to 10 parts by mass. In this case, if the amount used is less than 0.1 parts by mass, the sensitivity and developability tend to decrease. On the other hand, if it exceeds 20 parts by mass, the transparency to radiation decreases and it is difficult to obtain a rectangular resist pattern. Therefore, the elution suppression effect tends to be lost.

[1-3] Other additives The radiation-sensitive resin composition of the present invention preferably contains one or more additives in addition to the resin (A) and the acid generator (B). Other additives include nitrogen-containing compounds.

  Examples of the nitrogen-containing compound include tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine, tri-n-heptylamine, tri-n-octylamine, cyclohexyldimethylamine, dicyclohexylmethylamine, Tri (cyclo) alkylamines such as tricyclohexylamine, aromatic amines such as N-methylaniline, N, N-dimethylaniline and 2,6-diisopropylaniline, triethanolamine, N, N-di (hydroxyethyl) ) Alkanolamines such as aniline, N, N, N ′, N′-tetramethylethylenediamine, N, N, N ′, N′-tetrakis (2-hydroxypropyl) ethylenediamine, 1,3-bis [1- ( 4-Aminophenyl) -1-methylethyl] benzenetetramethyl Njiamin, bis (2-dimethylaminoethyl) ether, bis (2-diethylaminoethyl) ether.

  Nt-butoxycarbonyldi-n-octylamine, Nt-butoxycarbonyldi-n-nonylamine, Nt-butoxycarbonyldi-n-decylamine, Nt-butoxycarbonyldicyclohexylamine, Nt- Butoxycarbonyl-1-adamantylamine, Nt-butoxycarbonyl-2-adamantylamine, Nt-butoxycarbonyl-N-methyl-1-adamantylamine, (S)-(−)-1- (t-butoxy Carbonyl) -2-pyrrolidinemethanol, (R)-(+)-1- (t-butoxycarbonyl) -2-pyrrolidinemethanol, Nt-butoxycarbonyl-4-hydroxypiperidine, Nt-butoxycarbonylpyrrolidine, etc. .

  Nt-butoxycarbonylpiperazine, N, N-di-t-butoxycarbonyl-1-adamantylamine, N, N-di-t-butoxycarbonyl-N-methyl-1-adamantylamine, Nt-butoxycarbonyl -4,4'-diaminodiphenylmethane, N, N'-di-t-butoxycarbonylhexamethylenediamine, N, N, N'N'-tetra-t-butoxycarbonylhexamethylenediamine, N, N'-di- t-butoxycarbonyl-1,7-diaminoheptane, N, N′-di-t-butoxycarbonyl-1,8-diaminooctane, N, N′-di-t-butoxycarbonyl-1,9-diaminononane, N , N′-di-t-butoxycarbonyl-1,10-diaminodecane, N, N′-di-t-butoxycarbonyl-1,12 Diaminododecane, N, N′-di-t-butoxycarbonyl-4,4′-diaminodiphenylmethane, Nt-butoxycarbonylbenzimidazole, Nt-butoxycarbonyl-2-methylbenzimidazole, Nt-butoxy Nt-butoxycarbonyl group-containing amino compounds such as carbonyl-2-phenylbenzimidazole.

  In addition to pyridines such as 2-phenylpyridine, 4-phenylpyridine, 2-methyl-4-phenylpyridine and nicotinamide, piperazine such as piperazine and 1- (2-hydroxyethyl) piperazine, purine, 3- Piperidino-1,2-propanediol, 4-methylmorpholine, 1,4-dimethylpiperazine, 1,4-diazabicyclo [2.2.2] octane, benzimidazole, 2-phenylbenzimidazole, Nt-butoxycarbonyl Examples thereof include benzimidazole, Nt-butoxycarbonyl-2-methylbenzimidazole, Nt-butoxycarbonyl-2-phenylbenzimidazole and the like. In addition, the said nitrogen containing compound can be used individually or in mixture of 2 or more types.

  The compounding amount of the nitrogen-containing compound is preferably less than 10 parts by mass and more preferably less than 5 parts by mass with respect to 100 parts by mass of the resin (A). If the amount of the nitrogen-containing compound exceeds 10 parts by mass, the sensitivity as a resist film may be significantly reduced.

  As other additives other than the nitrogen-containing compound, various additives such as an alicyclic additive having an acid-dissociable group, a surfactant, and a sensitizer can be used.

  The alicyclic additive having an acid dissociable group is a component that exhibits an action of further improving dry etching resistance, pattern shape, adhesion to a substrate, and the like. Examples of such alicyclic additives include 1-adamantanecarboxylic acid, 2-adamantanone, 1-adamantanecarboxylic acid t-butyl, 1-adamantanecarboxylic acid t-butoxycarbonylmethyl, 1-adamantanecarboxylic acid α. -Butyrolactone ester, 1,3-adamantane dicarboxylic acid di-t-butyl, 1-adamantane acetate t-butyl, 1-adamantane acetate t-butoxycarbonylmethyl, 1,3-adamantane diacetate di-t-butyl, 2, Adamantane derivatives such as 5-dimethyl-2,5-di (adamantylcarbonyloxy) hexane;

Deoxycholate t-butyl, deoxycholate t-butoxycarbonylmethyl, deoxycholate 2-ethoxyethyl, deoxycholate 2-cyclohexyloxyethyl, deoxycholate 3-oxocyclohexyl, deoxycholate tetrahydropyranyl, deoxychol Deoxycholic acid esters such as acid mevalonolactone ester, tert-butyl lithocholic acid, t-butoxycarbonylmethyl lithocholic acid, 2-ethoxyethyl lithocholic acid, 2-cyclohexyloxyethyl lithocholic acid, 3-oxocyclohexyl lithocholic acid, lithocol Lithocholic acid esters such as tetrahydropyranyl acid, lithocholic acid mevalonolactone ester, dimethyl adipate, diethyl adipate, dipropyl adipate, di-n-adipate Chill, alkyl carboxylic acid esters such as adipate t- butyl or 3- [2-hydroxy-2,2-bis (trifluoromethyl) ethyl] tetracyclo [4.4.0.1 ^{2, 5.} 1 ^7,10 ] dodecane and the like. In addition, these alicyclic additives can be used individually or in mixture of 2 or more types.

  The surfactant is a component having an action of improving coatability, striation, developability and the like. Examples of such surfactants include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, and polyethylene glycol dilaurate. In addition to nonionic surfactants such as polyethylene glycol distearate, KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (manufactured by Kyoeisha Chemical Co., Ltd.), F-top EF301, EF303, EF352 (manufactured by Tochem Products), Megafax F171, F173 (manufactured by Dainippon Ink and Chemicals), Florard FC430, FC431 (Sumitomo 3M) Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (made by Asahi Glass Co., Ltd.), etc. Can do. In addition, these surfactant can be used individually or in mixture of 2 or more types.

  The sensitizer absorbs radiation energy and transmits the energy to the acid generator (B), thereby increasing the amount of acid produced. This component has the effect of improving the apparent sensitivity. Examples of such sensitizers include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, phenothiazines, and the like. In addition, these sensitizers can be used individually or in mixture of 2 or more types.

  In addition to the above-mentioned additives other than those described above, by adding a dye or a pigment, the latent image in the exposed area can be visualized and the influence of halation during exposure can be reduced. Moreover, the adhesiveness with a board | substrate can be improved by mix | blending an adhesion aid. Furthermore, an alkali-soluble resin, a low-molecular alkali solubility control agent having an acid-dissociable protecting group, an antihalation agent, a storage stabilizer, an antifoaming agent, and the like can be blended.

[1-4] Solvent Examples of the solvent include 2-butanone, 2-pentanone, 3-methyl-2-butanone, 2-hexanone, 4-methyl-2-pentanone, 3-methyl-2-pentanone, 3, Linear or branched ketones such as 3-dimethyl-2-butanone, 2-heptanone, 2-octanone, cyclopentanone, 3-methylcyclopentanone, cyclohexanone, 2-methylcyclohexanone, 2,6-dimethyl Cyclic ketones such as cyclohexanone and isophorone, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol mono-n-propyl ether acetate, propylene glycol mono-i-propyl ether acetate, propylene glycol mono-n-butyl Propylene glycol monoalkyl ether acetates such as chill ether acetate, propylene glycol mono-i-butyl ether acetate, propylene glycol mono-sec-butyl ether acetate, propylene glycol mono-t-butyl ether acetate, methyl 2-hydroxypropionate, 2-hydroxy Ethyl propionate, n-propyl 2-hydroxypropionate, i-propyl 2-hydroxypropionate, n-butyl 2-hydroxypropionate, i-butyl 2-hydroxypropionate, sec-butyl 2-hydroxypropionate, 2 -Alkyl 2-hydroxypropionates such as t-butyl hydroxypropionate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, 3- Methyl Kishipuropion acid, ethyl 3-ethoxypropionate and the like of 3-alkoxy propionic acid other alkyls such.

  Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di-n-propyl ether, diethylene glycol di-n-butyl ether, Ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol mono-n-propyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, 2-hydroxy-2-methyl Ethyl propionate, ethoxy Ethyl acetate, hydroxyethyl acetate, methyl 2-hydroxy-3-methylbutyrate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutylpropionate, 3-methyl-3 -Methoxybutyl butyrate, ethyl acetate, n-propyl acetate, n-butyl acetate, methyl acetoacetate, ethyl acetoacetate, methyl pyruvate, ethyl pyruvate, di-n-hexyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether And γ-butyrolactone.

  Among these, linear or branched ketones, cyclic ketones, propylene glycol monoalkyl ether acetates, alkyl 2-hydroxypropionate, alkyl 3-alkoxypropionate, γ-butyrolactone and the like are preferable. . These solvents can be used alone or in admixture of two or more.

[2] Upper Layer Film Forming Composition The upper layer film forming composition of the present invention is an upper layer film forming composition used for forming an upper layer film on the surface of a photoresist film, and is represented by the following formula (2-1): A resin (a) containing one or more repeating units represented by (2-5) and a solvent such as an alkyl ether having a C 4-10 alcohol and / or a C 4-10 alkyl chain. . Each component will be described below.

（前記一般式（２−１）、（２−２）、（２−３）、（２−４）及び（２−５）中、Ｒは水素、メチル基、又はトリフルオロメチル基を示し、Ｒ^２、Ｒ^３、Ｒ^４は互いに独立に、単結合、メチレン、炭素数２〜６の直鎖状若しくは分岐状のアルキレン基、又は炭素数４〜１２の脂環式のアルキレン基を示し、Ｒ^５は少なくとも一つの水素原子がフッ素原子で置換された炭素数１〜１０の直鎖状若しくは分岐状のアルキル基、又は炭素数３〜１０の脂環式のアルキル基を示し、Ｒ^６は単結合、メチレン、炭素数２〜６の直鎖状若しくは分岐状のアルキレン基、又は一般式、Ｃ（Ｏ）ＸＲ^８で表される基を示し、Ｘは酸素、硫黄、又はＮＨ基を示し、Ｒ^８はメチレン、炭素数２〜６の直鎖状又は分岐状のアルキレン基を示し、Ｒ^７は少なくとも一つの水素原子がフッ素原子で置換された炭素数１〜１２の直鎖状若しくは分岐状のアルキル基、又は少なくとも一つの水素原子がフッ素原子で置換された脂環式構造を有する炭素数１〜１２のアルキル基を示す） [2-1] Resin (a)
The resin (a) can contain one or more repeating units represented by the following general formulas (2-1) to (2-5).

(In the general formulas (2-1), (2-2), (2-3), (2-4) and (2-5), R represents hydrogen, a methyl group, or a trifluoromethyl group, R ² , R ³ , and R ⁴ each independently represent a single bond, methylene, a linear or branched alkylene group having 2 to 6 carbon atoms, or an alicyclic alkylene group having 4 to 12 carbon atoms, R ⁵ represents a linear or branched alkyl group having 1 to 10 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom, or an alicyclic alkyl group having 3 to 10 carbon atoms, and R ⁶ represents A single bond, methylene, a linear or branched alkylene group having 2 to 6 carbon atoms, or a group represented by the general formula, C (O) XR ⁸ , wherein X represents an oxygen, sulfur, or NH group , R ⁸ represents methylene, a linear or branched alkylene group having 2 to 6 carbon atoms, and R ⁷ is small Or a linear or branched alkyl group having 1 to 12 carbon atoms in which one hydrogen atom is substituted with a fluorine atom, or an alicyclic structure in which at least one hydrogen atom is substituted with a fluorine atom. Represents an alkyl group of ˜12)

  Examples of the monomer that gives the repeating unit represented by the general formula (2-1) include (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-3-propyl). ) Ester, (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-butyl) ester, (meth) acrylic acid (1,1,1-trifluoro-2) -Trifluoromethyl-2-hydroxy-5-pentyl) ester, (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester, (meth) acrylic Acid 2-{[5- (1 ′, 1 ′, 1′-trifluoro-2′-trifluoromethyl-2′-hydroxy) propyl] bicyclo [2.2.1] heptyl} ester (Meth) acrylic acid 3-{[8- (1 ′, 1 ′, 1′-trifluoro-2′-trifluoromethyl-2′-hydroxy) propyl] tetracyclo [6.2.1.13,6. 02,7] dodecyl} ester and the like.

  Examples of the monomer that gives the repeating unit represented by the general formula (2-2) include (meth) acrylic acid, bicyclo [2.2.1] hept-5-en-2-ylmethanecarboxylic acid, 2 -Bicyclo [2.2.1] hept-5-enecarboxylic acid, 4-tricyclo [5.2.1.02,6] dec-8-enecarboxylic acid, tricyclo [5.2.1.02,6 ] Deca-8-en-4-ylmethanecarboxylic acid, bicyclo [2.2.1] hept-5-en-2-ylmethanecarboxylic acid and the like.

  Examples of the monomer that gives the repeating unit represented by the general formula (2-3) include (((trifluoromethyl) sulfonyl) amino) ethyl-1-methacrylate, 2-(((trifluoromethyl) sulfonyl). Amino) ethyl-1-acrylate and the compound represented by the following formula are mentioned.

  Examples of the monomer that gives the repeating unit represented by the general formula (2-4) include vinyl sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methyl-1-propanesulfonic acid, and 4-vinyl. -1-benzenesulfonic acid and the like.

  Examples of the monomer that gives the repeating unit representing the general formula (2-5) include trifluoromethyl (meth) acrylate, 2,2,2-trifluoroethyl (meth) acrylate, and perfluoro. Ethyl (meth) acrylate, perfluoro n-propyl (meth) acrylate, perfluoro i-propyl (meth) acrylate, perfluoro n-butyl (meth) acrylate, perfluoro i-butyl ( (Meth) acrylic acid ester, perfluoro t-butyl (meth) acrylic acid ester, 2- (1,1,1,3,3,3-hexafluoropropyl) (meth) acrylic acid ester, 1- (2,2 , 3,3,4,4,5,5-octafluoropentyl) (meth) acrylic ester, perfluorocyclohexane Silmethyl (meth) acrylic acid ester, 1- (2,2,3,3,3-pentafluoropropyl) (meth) acrylic acid ester, 1- (3,3,4,4,5,5,6,6 , 7,7,8,8,9,9,10,10,10-heptadecafluorodecyl) (meth) acrylic acid ester, 1- (5-trifluoromethyl-3,3,4,4,5, 6,6,6-octafluorohexyl) (meth) acrylic acid ester and the like.

  The resin (a) contains a repeating unit derived from another radical polymerizable monomer (hereinafter sometimes referred to as “other repeating unit”) and a structural unit derived from an acid-dissociable group-containing monomer. Can be made.

  Examples of the monomer used for producing the other repeating unit include 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, Toxipropylene 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) Acryle DOO, 1-adamantyl-1-methylethyl (meth) acrylate, 1-bicyclo [2.2.1] (meth) acrylic acid alkyl esters such as heptyl-1-methylethyl (meth) acrylate.

  Dicarboxylic acid diesters such as diethyl maleate, diethyl fumarate, diethyl itaconate, (meth) acrylic acid aryl esters such as phenyl (meth) acrylate, benzyl (meth) acrylate, styrene, α-methylstyrene, m-methylstyrene, Aromatic vinyls such as p-methylstyrene, vinyltoluene and p-methoxystyrene, radical polymerizable monomers containing nitrile groups such as acrylonitrile and methacrylonitrile, radical polymerizable monomers containing amide bonds such as acrylamide and methacrylamide Isomers, 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. . Of these, (meth) acrylic acid alkyl esters, nitrile group-containing radical polymerizable monomers, amide bond-containing radical polymerizable monomers, and hydroxyl group-containing (meth) acrylic acid alkyl esters are preferred. In addition, these monomers can be used individually or in combination of 2 or more types.

  It is preferable that the ratio of said other repeating unit contains less than 40 mol% with respect to all the repeating units of resin (a) containing this other repeating unit.

  Examples of the polymerization solvent used in producing the resin (a) 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, etc. .

  Aromatic hydrocarbons such as toluene and xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, ketones such as 4-hydroxy-4-methyl-2-pentanone, diacetone alcohol, ethyl acetate, butyl acetate, 2-hydroxy Methyl propionate, ethyl 2-hydroxy-2-methylpropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutanoate, methyl 3-methoxypropionate And esters such as ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate and methyl 3-ethoxypropionate. Of these, cyclic ethers, polyhydric alcohol alkyl ethers, polyhydric alcohol alkyl ether acetates, ketones, and esters are preferred.

  The polystyrene-reduced weight average molecular weight (hereinafter may be referred to as “Mw”) by gel permeation chromatography (GPC) of the resin (a) is preferably 2,000 to 100,000, respectively. , 500 to 50,000, and more preferably 3,000 to 20,000. If the Mw of the resin (a) is less than 2,000, the water resistance and mechanical properties as the upper layer film may be remarkably lowered. On the other hand, when it exceeds 100,000, there is a possibility that the solubility in the above-mentioned solvent sometimes becomes extremely poor. Moreover, ratio (Mw / Mn) of Mw of the resin (a) and polystyrene-equivalent number average molecular weight (hereinafter may be referred to as “Mn”) by gel permeation chromatography (GPC) is 1 to 5. It is preferable that it is 1-3.

  In addition, resin (a) is so preferable that there are few impurities, such as a halogen and a metal, and it can further improve the applicability | paintability as an upper layer film | membrane, and the uniform solubility to an alkali developing solution by reducing an impurity. Examples of the purification method of the resin (a) 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. be able to.

[2-2] Solvent The upper film forming composition of the present invention contains one or more solvents selected from alcohols having 4 to 10 carbon atoms and / or alkyl ethers having an alkyl chain having 4 to 10 carbon atoms. be able to. As the composition of the solvent, the alcohol having 4 to 10 carbon atoms is 0 to 50% by mass in the total solvent, preferably 0 to 30% by mass, more preferably 0 to 10% by mass and contained as a sub-solvent. Further, alkyl ether is preferable as the main solvent. Suppressing deterioration of lithography performance, such as intermixing with the photoresist film, when the upper layer film-forming composition contains an alcohol having 4 to 10 carbon atoms as a secondary solvent on the photoresist film. Can do.

  Examples of the alcohol having 4 to 10 carbon atoms include 1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, tert-amyl alcohol, Neopentyl alcohol, 2-methyl-1-butanol, 3-methyl-1-butanol, 3-methyl-3-pentanol, cyclopentanol, 1-hexanol, 2-hexanol, 3-hexanol, 2,3-dimethyl 2-butanol, 3,3-dimethyl-1-butanol, 3,3-dimethyl-2-butanol, 2-diethyl-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-pentanol, 4-methyl-3-pentanol, it may be mentioned cyclohexanol.

  Examples of the alkyl ether having an alkyl chain having 4 to 10 carbon atoms include dipropyl ether, diisopropyl ether, butyl methyl ether, butyl ethyl ether, butyl propyl ether, dibutyl ether, diisobutyl ether, tert-butyl-methyl ether, tert -Butyl ethyl ether, tert-butyl propyl ether, di-tert-butyl ether, dipentyl ether, diisoamyl ether, cyclopentyl methyl ether, cyclohexyl methyl ether, cyclopentyl ethyl ether, cyclohexyl ethyl ether, cyclopentyl propyl ether, cyclopentyl-2-propyl ether , Cyclohexylpropyl ether, cyclohexyl-2-propyl ether, cyclopentyl Chirueteru, cyclopentyl -tert- butyl ether, cyclohexyl ether, and cyclohexyl -tert- butyl ether.

  The upper layer film-forming composition of the present invention can be mixed with one or more of the above solvents. Further, other solvents can be appropriately contained.

  Other solvents include, for example, ethylene glycol, propylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether. , Diethylene glycol ethyl methyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, etc., ethylene glycol ethyl ether acetate, diethylene glycol ethyl ether acetate, propylene glycol ethyl ether acetate, propylene glycol monomethyl Ether acetate, etc., tetrahydrofuran, dioxane, etc., decane, dodecane, undecane, etc., benzene, toluene, xylene, etc., acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, 4-hydroxy-4-methyl-2-pentanone, diacetone alcohol, etc. Ethyl acetate, butyl acetate, ethyl 2-hydroxypropionate, methyl 2-hydroxy-2-methylpropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, 2-hydroxy-3-methylbutane Examples include methyl acrylate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, and the like.

[2-3] Additives The upper layer film-forming composition of the present invention may contain a surfactant or the like for the purpose of improving coating properties, antifoaming properties, leveling properties and the like.

  Examples of the surfactant include, for example, BM-1000, BM-1100 (manufactured by BM Chemie), Megafuck F142D, F172, F173, F173 (manufactured by Dainippon Ink and Chemicals, Inc.), Fluorard FC-135, FC-170C, FC-430, FC-431 (manufactured by Sumitomo 3M), Surflon S-112, S-113, S-131, S-141, S-145 (Asahi Glass), SH-28PA, -190, -193, SZ-6032, SF-8428 (Toray Dow Corning Silicone), Emulgen A-60, 104P, 306P (Kao) Fluorosurfactant that has been used can be used. It is preferable that the compounding quantity of these surfactant is 5 mass parts or less with respect to 100 mass parts of total amounts of resin (A) and resin (B).

  The upper layer film-forming composition of the present invention can further contain a crosslinking agent and an acidic compound.

  As the crosslinking agent for the protective film of the present invention, any crosslinking agent that is soluble in the solvent can be used. Among these, a nitrogen-containing compound having an amino group and / or an imino group substituted with a hydroxyalkyl group and / or an alkoxyalkyl group can be preferably used.

  The nitrogen-containing compound is preferably at least one selected from melamine derivatives, guanamine derivatives, glycoluril derivatives, succinylamide derivatives, and urea derivatives.

  Specifically, these nitrogen-containing compounds include, for example, the above melamine compounds, urea compounds, guanamine compounds, acetoguanamine compounds, benzoguanamine compounds, glycoluril compounds, succinylamide compounds, ethylene urea compounds. Etc. are reacted with formalin in boiling water to form methylol, or further reacted with a lower alcohol, specifically methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, etc. Can be obtained.

  As such a cross-linking agent, tetrabutoxymethylated glycoluril is more preferably used.

  Furthermore, as the crosslinking agent, a condensation reaction product of a hydrocarbon compound substituted with at least one hydroxyl group and / or alkyloxy group and a monohydroxymonocarboxylic acid compound can also be suitably used.

  As the monohydroxymonocarboxylic acid, those in which a hydroxyl group and a carboxyl group are bonded to the same carbon atom or two adjacent carbon atoms are preferable.

  An acidic component (desirably, a fluorocarbon compound) can be further added to the upper layer film-forming composition of the present invention. Such an acidic component preferably has a holding and stabilizing effect. The fluorine-containing compounds that bring about the above-described action are shown below. These fluorine-containing compounds are not subject to the Important New Use Rules (SNUR) and are usable chemical substances.

Examples of these fluorocarbon compounds include (C ₄ F ₉ SO ₂ ) ₂ NH, (C ₃ F ₇ SO ₂ ) ₂ NH, C ₁₀ F ₂₁ COOH, and the following formulas (3-1) and (3-2): ) Is preferred.

  The upper layer film-forming composition of the present invention contains the resin (a), and after the upper layer film-forming composition is applied on the surface of the photoresist film, pre-baking is performed at 50 to 150 ° C. for 1 to 360 seconds. When the upper layer film is formed by performing the step, the receding contact angle θ of the upper layer film measured with respect to water is 70 ° or more (the receding contact angle θ: 25 μL disposed on the upper layer film). Of water droplets at a rate of 10 μL / min). By having a sufficiently high receding contact angle in this way, even when forming a resist pattern at a high scan speed, it is difficult for droplets to remain on the photoresist film, effectively suppressing the occurrence of defects such as watermark defects. can do.

[3] Photoresist Pattern Forming Method Next, an embodiment of the photoresist pattern forming method of the present invention will be described. The method for forming a photoresist pattern of the present invention comprises a step of applying a photoresist composition on a substrate to form a photoresist film (step (1)), and the above-described upper layer film-forming composition is applied to the photoresist film. A step of applying and forming an upper layer film (step (2)), an immersion medium is disposed between the upper layer film and the lens, and the photo is passed through the immersion medium and a mask having a predetermined pattern. Irradiating the resist film and the upper layer film with exposure light and then developing the resist pattern to obtain a resist pattern (step (3)).

Process (1)
Step (1) is a step of forming a photoresist film by applying a photoresist composition on a substrate. As the substrate, a silicon wafer, a silicon wafer coated with aluminum, or the like is usually used. In order to maximize the characteristics of the photoresist film, an organic or inorganic antireflection film is preferably formed on the surface of the substrate in advance (for example, Japanese Patent Publication No. 6-12252). (See the official gazette).

  The type of the material for forming the photoresist film is not particularly limited, and it is appropriately selected from materials conventionally used for forming a photoresist film according to the purpose of use of the resist. do it. However, it is preferable to use a chemically amplified resist material containing an acid generator, particularly a positive resist material. Examples of the chemically amplified positive resist material include a radiation sensitive resin composition containing an acid dissociable group-modified alkali-soluble resin and a radiation sensitive acid generator as essential components. In such a resin composition, an acid is generated from an acid generator by irradiation (exposure), and an acid-dissociable group that protected an acidic group (for example, a carboxyl group) of the resin by the action of the generated acid. Dissociates to expose acidic groups. Accordingly, the alkali solubility of the exposed portion of the resist is increased, and the exposed portion is dissolved and removed by the alkali developer, so that a positive resist pattern can be formed.

  For the photoresist film, a solvent is added to the resin component for forming the photoresist film to obtain a solution in which the total solid content concentration is adjusted to 0.2 to 20% by mass. The obtained solution is filtered through a filter having a pore size of about 30 nm to prepare a coating solution, and this coating solution is applied to the substrate using a conventionally known coating method such as spin coating, cast coating, roll coating or the like. It can form by apply | coating to. This photoresist film may be pre-baked (hereinafter may be referred to as “PB”) in order to volatilize the solvent. In forming the photoresist film, the coating solution may be prepared by itself or a commercially available resist solution may be used as the coating solution.

Process (2)
Step (2) is a step of forming the upper film by applying the above-described upper film forming composition to the photoresist film. This step is a step of forming the upper layer film by applying the above-described upper layer film forming composition on the surface of the photoresist film formed in the step (1) and preferably baking again. By forming the upper layer film, the immersion liquid is prevented from coming into direct contact with the photoresist film during the immersion exposure, and the lithography performance of the photoresist film is reduced by the penetration of the immersion liquid, or the photoresist film It is possible to effectively prevent the lens of the projection exposure apparatus from being contaminated by the components eluted from

  The thickness of the upper layer film is preferably as close as possible to an odd multiple of λ / 4m (where λ is the wavelength of radiation and m is the refractive index of the protective film). This is because the reflection suppressing effect at the upper interface of the photoresist film is increased.

Step (3)
In the step (3), an immersion medium is disposed between the upper layer film and the lens, a mask is disposed on the lens, and the photoresist is passed through the immersion medium and a mask having a predetermined pattern. This is a step of obtaining a resist pattern by irradiating the film and the upper film with exposure light and then developing the film.

  As the immersion medium, a liquid having a higher refractive index than air is usually used. Specifically, water is preferably used, and pure water is more preferably used. In addition, you may adjust pH of immersion liquid as needed. With this immersion medium interposed (that is, with the immersion medium filled between the lens of the exposure apparatus and the photoresist film), the photoresist film is irradiated with radiation through a mask having a predetermined pattern. To expose.

  The radiation that can be used in the immersion exposure may be appropriately selected according to the type of the photoresist film or the upper layer film to be used. For example, visible light, g-ray having a wavelength of 436 nm, i-line having a wavelength of 365 nm Various types of radiation such as ultraviolet rays such as excimer laser, deep ultraviolet rays such as excimer laser, X-rays such as synchrotron radiation, and charged particle beams such as electron beams can be used. Among these, it is preferable to use a KrF excimer laser (wavelength 248 nm) or an ArF excimer laser (wavelength 193 nm). Moreover, what is necessary is just to set suitably exposure conditions, such as a radiation dose, according to the compounding composition of a radiation sensitive resin composition, the kind of additive, etc.

  In order to improve the resolution, pattern shape, developability, and the like of the photoresist film, baking (PEB) is preferably performed after exposure. The firing temperature is appropriately adjusted depending on the type of the radiation-sensitive resin composition used, and is usually 30 to 200 ° C, preferably 50 to 150 ° C.

  If development is performed after exposure or after PEB and washing is performed as necessary, a desired photoresist pattern can be formed. The upper layer film is formed by the upper layer film forming composition which is one embodiment of the present invention. Therefore, this upper layer film does not need to be removed by a separate peeling process, and can be easily removed during development or washing after development. In developing, an alkaline developer is usually used.

  Examples of the developer include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, dimethylethanol. Amine, triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, 1,5-diazabicyclo- [4. 3.0] It is preferable to use an alkaline aqueous solution in which at least one alkaline compound such as 5-nonane is dissolved. Especially, the aqueous solution of tetraalkylammonium hydroxide can be used suitably.

  For example, an appropriate amount of a water-soluble organic solvent including alcohols such as methanol and ethanol, and a surfactant can be added to the developer. In addition, when developing using said alkaline aqueous solution, it wash | cleans with water after image development normally. In addition, if it dries suitably after image development or the water washing as needed, the target photoresist pattern can be formed.

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

Preparation of Radiation Sensitive Resin Composition Resin (A-1) contained in the radiation sensitive composition of the present invention was synthesized by the following method.

Molecular weight (Mw, Mn) measurement method Mw and Mn of resins (A-1) to (A-3) were measured using a GPC column (product of Tosoh Corporation) on a high-speed GPC device (model "HLC-8120") manufactured by Tosoh Corporation. Name “G2000HXL”: 2; “G3000HXL”: 1; “G4000HXL”: 1), standard flow rate of 1.0 ml / min, elution solvent tetrahydrofuran, column temperature 40 ° C. Measured by gel permeation chromatography (GPC).

Synthesis example 1
First, 31.30 g (30 mol%) of the following compound (M-1), 29.09 g (34 mol%) of the compound (M-2), and 39.61 g (36 mol%) of the compound (M-4) were A monomer solution dissolved in 200 g of butanone and further charged with 3.85 g of 2,2′-azobis (isobutyronitrile) was prepared. On the other hand, 100 g of 2-butanone was charged into a 1000 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. Using a dropping funnel, a monomer solution prepared in advance was added dropwise over 3 hours. The polymerization start was carried out for 6 hours with the start of dropping as the polymerization start time. After completion of the polymerization, the polymerization solution was cooled to 30 ° C. or less by water cooling. After cooling, it was poured into 2000 g of methanol, and the precipitated white powder was filtered off. The filtered white powder was washed twice with 400 g of methanol as a slurry. Thereafter, the mixture was filtered and dried at 50 ° C. for 17 hours to obtain a white powder copolymer (73 g, recovery rate 73%).

The obtained copolymer has Mw of 5300 and Mw / Mn of 1.67, and as a result of ¹³ C-NMR analysis, the repeating unit derived from compound (M-1), derived from compound (M-2) The content of the repeating unit derived from the compound (M-4) was 30.6: 34.1: 35.3 (mol%). This was made into resin (A-1).

Acid generator (C)
C-1: Triphenylsulfonium 2- (bicyclo [2.2.1] hepta-2'-yl) -1,1-difluoroethanesulfonate

Nitrogen-containing compound (D)
D-1: Nt-butoxycarbonyl-4-hydroxypiperidine

Solvent (E)
E-1: Propylene glycol monomethyl ether acetate, E-2: Cyclohexanone, E-3: γ-butyrolactone

Preparation of Upper Layer Film-Forming Composition Resins (a-1) to (a-3) contained in the upper layer film forming composition of the present invention were synthesized by the following method.

Synthesis example 2
A 2-liter four-necked flask equipped with a reflux condenser and a stirrer was charged with 750 g of isobutyl alcohol, and nitrogen blowing was started. After raising the temperature to 80 ° C. with stirring, as a methacrylic acid monomer, a mixture of acrylic acid 60 g, dicyclopentanyl methacrylate 40 g, n-butyl acrylate 40 g, cyclohexyl methacrylate 20 g, heptadecafluorodecyl methacrylate 40 g Then, a mixed solution composed of 50 g of isobutyl alcohol as a solvent and 1.7 g of benzoyl peroxide as a polymerization initiator was dropped from separate dropping nozzles over 4 hours. The dropping was continuously performed, and the dropping rate of each component was constant throughout the dropping. After completion of the dropwise addition, the polymerization reaction solution was aged at 80 ° C. for 4 hours as it was, and then the polymerization reaction solution was heated up and aged for 1 hour until reflux of the solvent was observed, thereby completing the polymerization. Thereafter, the polymerization solution was charged into a large amount of n-hexane to obtain a white powder copolymer polymer (recovery rate: 90%). As a result of ¹³ C-NMR analysis, this polymer has a content of each repeating unit derived from acrylic acid, dicyclopentanyl methacrylate, n-butyl acrylate, cyclohexyl methacrylate, and heptadecafluorodecyl methacrylate. The copolymer was 52: 12: 9: 21: 6 (mol%). This polymer is referred to as “resin (a-1)”.

Synthesis example 3
First, 46.95 g (85 mol%) of methacrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester and an initiator (2,2′-azobis- ( A monomer solution was prepared by dissolving 6.91 g of methyl 2-methylpropionate)) in 100 g of isopropanol. Meanwhile, 50 g of isopropanol was charged into a 500 ml three-necked flask equipped with a thermometer and a dropping funnel, and purged with nitrogen for 30 minutes. After purging with nitrogen, the inside of the flask was heated to 80 ° C. while stirring with a magnetic stirrer. Using a dropping funnel, a monomer solution prepared in advance was added dropwise over 2 hours. After completion of the dropwise addition, the reaction is further performed for 1 hour, and 10 g of an isopropanol solution of 3.05 g (15 mol%) of vinyl sulfonic acid is used as a monomer used for producing the repeating unit represented by the general formula (1-1). Was added dropwise over 30 minutes, and then the reaction was further carried out for 1 hour. It cooled to 30 degrees C or less, and the copolymer liquid was obtained.

  The obtained copolymer 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. 50 g of methanol and 600 g of n-hexane were put into the above separatory funnel, followed by separation and purification. After separation, the lower layer liquid was recovered. The recovered lower layer solution was replaced with 4-methyl-2-pentanol, and the total amount was adjusted to 250 g. After the adjustment, 250 g of water was added for separation and purification. After separation, the upper layer liquid was recovered. The recovered upper layer liquid was replaced with 4-methyl-2-pentanol to obtain a resin solution. The solid content concentration of the sample (resin solution) after substitution with 4-methyl-2-pentanol was measured by weighing 0.3 g of the resin solution in an aluminum dish and heating on a hot plate at 140 ° C. for 1 hour. Then, the mass was calculated from the mass of the resin solution before heating and the mass of the residue (after heating). This solid content concentration was used for the preparation of the upper layer film-forming composition solution and the recovery rate calculation.

  The copolymer contained in the obtained resin solution had Mw of 9,760, Mw / Mn of 1.51, and a recovery rate of 65%. Moreover, the repeating unit derived from methacrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester contained in this copolymer, and derived from vinyl sulfonic acid The content of the repeating unit was 95: 5 (mol%). This copolymer is referred to as “resin (a-2)”.

Synthesis example 4
First, 50 g of methacrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester and 1.95 g of 2,2-azobis (methyl 2-methylisopropionate) A monomer solution previously dissolved in 50 g of methyl ethyl ketone was prepared. On the other hand, 50 g of methyl ethyl ketone was put into a 500 ml three-necked flask equipped with a thermometer and a dropping funnel, and purged with nitrogen for 30 minutes. After purging with nitrogen, the inside of the flask was heated to 80 ° C. while stirring with a magnetic stirrer. Using the dropping funnel, the monomer solution prepared in advance was dropped over 3 hours. After completion of the dropwise addition, the reaction was carried out for 1 hour, and 1.17 g of 2,2-azobis (methyl 2-methylisopropionate) was further added. Thereafter, the reaction was further performed for 2 hours, and the mixture was cooled to 30 ° C. or less to obtain a copolymer liquid.

  150 g of the obtained copolymer solution was transferred to a separatory funnel, and 50 g of methanol and 600 g of n-hexane were added to the separatory funnel for separation and purification. After separation, the lower layer solution was recovered. The recovered lower layer solution was diluted with methyl ethyl ketone to 100 g, and again transferred to a separatory funnel. 50 g of methanol and 600 g of n-hexane were put into a 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 to carry out liquid separation purification, and after separation, the upper layer liquid was recovered. The recovered upper layer liquid was replaced with 4-methyl-2-pentanol to obtain a resin solution. The solid content concentration of this resin solution was calculated in the same manner as in Synthesis Example 1 above. The copolymer contained in the obtained resin solution had Mw of 11,090, Mw / Mn of 1.52, and a recovery rate of 70%. This copolymer was designated as resin (a-3).

Additive (F)
F-1: (CF ₂ ) ₃ (SO ₂ ) ₂ NH

Solvent (G)
G-1: 4-methyl-2-pentanol, G-2: diisoamyl ether

  Various evaluations shown below were performed on this upper layer film-forming composition.

Evaluation method Method of measuring receding contact angle First, an upper layer film-forming composition was spin-coated on an 8-inch silicon wafer, and heated at 90 ° C. for 60 seconds to form a coating film (upper layer film) having a film thickness of 90 nm. Thereafter, using the trade name “DSA-10” (manufactured by KRUS), the receding contact angle was quickly measured by the following procedure in an environment of room temperature: 23 ° C., humidity: 45%, and normal pressure.

  The wafer stage position of the product name “DSA-10” (manufactured by KRUS) is adjusted, and the wafer is set on the adjusted stage. Next, water is injected into the needle, and the position of the needle is finely adjusted to an initial position where water droplets can be formed on the set wafer. Thereafter, water is discharged from the needle to form a 25 μL water droplet on the wafer. The needle is once withdrawn from the water droplet, and the needle is pulled down again to the initial position and placed in the water droplet. Subsequently, a water droplet is sucked with a needle at a speed of 10 μL / min for 90 seconds, and at the same time, the contact angle is measured once per second (90 times in total). Of these, the average value for the contact angle for 20 seconds from the time when the measured value of the contact angle was stabilized was calculated as the receding contact angle (°). The evaluation results are shown in Table 3. In Table 3, “retreating contact angle” indicates this evaluation.

Evaluation method for intermixing (intermixing)
This evaluation was performed to evaluate that intermixing with the photoresist film is prevented. First, a radiation sensitive resin composition was spin-coated on an 8-inch silicon wafer that had been previously subjected to HMDS treatment (100 ° C., 60 seconds) using a trade name “CLEAN TRACK ACT8”. PB shown in Table 1 was performed to form a 120 nm thick coating film (photoresist film). On the formed coating film, the upper layer film-forming composition was spin-coated, and PB (90 ° C., 60 seconds) was performed to form a coating film having a thickness of 90 nm. Then, PEB shown in Table 1 was performed, and then using the product name “CLEAN TRACK ACT8”, paddle development (developer: 2.38% TMAH aqueous solution) was performed for 60 seconds with an LD nozzle to remove the upper layer film. did. Although the upper layer film is removed by the above development, the photoresist film remains as it is because it is not exposed. Before and after development, the film thickness of the photoresist film is measured using the trade name “Lambda Ace VM90” (Dainippon Screen Co., Ltd.). If the change rate of the film thickness is within 5%, the photoresist film In other words, it was judged that there was no intermixing between the upper film and the film was evaluated as “◯”, and when the film thickness change rate exceeded 5%, it was evaluated as “x”. The evaluation results are shown in Table 3. In Table 3, “Intermixing” indicates this evaluation.

Patterning evaluation This evaluation was performed to evaluate the formation of a high-resolution resist pattern. First, using a trade name “CLEAN TRACK ACT8” on an 8-inch silicon wafer, a composition for a lower antireflection film (trade name “ARC29A” (Brewer Science Co., Ltd.)) was spin-coated, and PB ( (205 ° C., 60 seconds) to form a 77 nm-thickness coating film (lower antireflection film). A radiation sensitive resin composition was spin-coated on the formed lower antireflection film, and PB shown in Table 1 was performed to form a coating film (photoresist film) having a thickness of 120 nm.

  On the formed photoresist film, the upper layer film-forming composition was spin-coated, and PB (90 ° C., 60 seconds) was performed to form a coating film (upper layer film) having a thickness of 90 nm. Next, using an ArF projection exposure apparatus (model number “S306C”, manufactured by Nikon Corporation), exposure is performed under optical conditions of NA: 0.78, sigma: 0.85, 2/3 Ann, and trade name “CLEAN TRACK ACT8” From the rinse nozzle, ultrapure water was discharged onto the wafer for 60 seconds, and spin-drying was performed at 4000 rpm for 15 seconds. Thereafter, PEB shown in Table 1 was performed using a hot plate having a trade name “CLEAN TRACK ACT8”, and then paddle development (developer: 2.38% TMAH aqueous solution) was performed for 30 seconds using an LD nozzle. After rinsing with ultra pure water, spin drying was performed by shaking off at 4000 rpm for 15 seconds.

Measurement of elution volume (elution volume)
As shown in FIG. 1 and FIG. 2, 8-inch silicon on which a HMDS (hexamethyldisilazane) treatment layer 8 was previously performed using “CLEAN TRACK ACT8” (manufactured by Tokyo Electron) under treatment conditions of 100 ° C. for 60 seconds. A wafer 2 was prepared. A silicon rubber sheet (manufactured by Kureha Elastomer Co., Ltd., thickness: 1.0 mm, shape: 30 cm on a side) is formed on the surface of the 8-inch silicon wafer 2 on the side of the HMDS treatment layer, and the center is cut into a circular shape having a diameter of 11.3 cm. (Square) 4 was placed. At this time, the center portion (the cut-out portion 5) of the silicon rubber sheet 4 in the center portion of the 8-inch silicon wafer 2 was positioned. Next, 10 mL of ultrapure water 6 was filled in the hollowed portion 5 of the silicon rubber sheet 4 using a 10 mL hole pipette.

  On the other hand, a lower antireflection film 10, a resist film 13 and an upper film 12 were formed in advance. An 8-inch silicon wafer 15 different from the 8-inch silicon wafer 2 is prepared, and the 8-inch silicon wafer 15 is arranged so that the upper layer film 12 is located on the silicon rubber sheet 4 side, that is, with the upper layer film 12 and The ultrapure water 6 was placed in contact with the ultrapure water 6 so as not to leak.

  The lower antireflection film 10, the resist film 13 and the upper film 12 on the other 8-inch silicon wafer 15 were formed as follows. First, a composition for a lower antireflection film (“ARC29A”, manufactured by Brewer Science) was applied using the “CLEAN TRACK ACT8” so as to form a lower antireflection film having a thickness of 77 nm. Next, the radiation sensitive resin composition (α) is spin-coated on the lower antireflection film using the “CLEAN TRACK ACT8” and baked at 115 ° C. for 60 seconds to form a resist having a thickness of 205 nm. A coating 13 was formed. Thereafter, the upper film forming composition was applied onto the resist film 13 to form the upper film 12.

  After placing the upper layer film 12 so as to be positioned on the silicon rubber sheet 4 side, it was kept in that state for 10 seconds. Thereafter, the other 8-inch silicon wafer 15 was removed, and the ultrapure water 6 that had been in contact with the upper layer film 12 was collected with a glass syringe. This ultrapure water 6 was used as a sample for analysis. Note that the recovery rate of the ultrapure water 6 filled in the cut-out portion 5 of the silicon rubber sheet 4 was 95% or more.

  With respect to the formed resist pattern, the exposure amount for forming a line-and-space pattern (1L1S) having a line width of 90 nm in a one-to-one line width was determined as the optimum exposure amount. For the measurement, a scanning electron microscope (trade name “S-9380” (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-4200”, manufactured by Hitachi Keiki Co., Ltd.). FIG. 3 is a cross-sectional view schematically showing the shape of a line and space pattern. The line width Lb in the middle of the film of the pattern 2 formed on the substrate 1 and the line width La in the upper part of the film were measured, and 0.9 ≦ (La−Lb) /Lb≦1.1. The case was evaluated as “X” when “O”, (La−Lb) / Lb <0.9, or (La−Lb) / Lb> 1.1. The evaluation results are shown in Table 3. In Table 3, “patterning” indicates this evaluation.

  As is apparent from Table 3, it can be seen that intermixing is less likely to occur in Examples 1 to 4 than Comparative Examples 1 and 2, and it is assumed that no major problems occur in the actual etching process.

  The resist pattern forming method of the present invention comprises a resin (A) containing more than 60 mol% of a repeating unit that becomes alkali-soluble by the action of an acid and a radiation-sensitive acid generator (B). By forming the upper layer film with the upper layer film composition of the present invention on the resist film formed with the radiation sensitive resin composition, the film thickness of the unexposed area after development and peeling is maintained at the thickness at the time of coating. Is done. Therefore, the resist pattern forming method of the present invention can maintain a film thickness that can withstand dry etching even after immersion exposure / development, and a semiconductor device manufacturing process that is expected to be further miniaturized in the future. Can be used very suitably.

It is a figure which shows typically the state which mounts an 8-inch silicon wafer on a silicon rubber sheet so that an ultrapure water may not leak in the measurement of the elution amount of the upper film formed with the upper film formation composition of this invention. It is sectional drawing in the measurement state of the elution amount of the upper film formed with the upper film formation composition of this invention. It is sectional drawing which shows the shape of a line and space pattern typically.

Explanation of symbols

2: 8 inch silicon wafer, 4: silicon rubber sheet, 5: hollowed out part, 6: ultrapure water, 8: hexamethyldisilazane treatment layer, 10: lower antireflection film, 12: upper film, 13: resist film, 15: 8-inch silicon wafer, 16: substrate, 18: pattern, La: line width at the top of the film, Lb: line width at the middle of the film.

Claims (3)

A radiation-sensitive resin composition containing a resin (A) containing a repeating unit containing an acid-dissociable group in excess of 60 mol% and a radiation-sensitive acid generator (B) is coated on a substrate. And forming a photoresist film,
A step of applying an upper layer film-forming composition containing an alcohol having 4 to 10 carbon atoms in a mass ratio of 0 to 50% by mass or less to the photoresist film to form an upper layer film;
An immersion medium is disposed between the upper layer film and the lens, and the photoresist film and the upper layer film are irradiated with exposure light through the immersion medium and the mask having a predetermined pattern, and then developed. And a step of obtaining a resist pattern. 2. The photoresist pattern according to claim 1, wherein the upper layer film-forming composition contains a resin (a) containing at least one repeating unit represented by the following general formulas (1-1) to (1-5). Forming method.

(In the general formulas (1-1), (1-2), (1-3), (1-4) and (1-5), R ¹ represents hydrogen, a methyl group, or a trifluoromethyl group. , R ² , R ³ and R ⁴ each independently represent a single bond, methylene, a linear or branched alkylene group having 2 to 6 carbon atoms, or an alicyclic alkylene group having 4 to 12 carbon atoms. , R ⁵ represents a linear or branched alkyl group having 1 to 10 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom, or an alicyclic alkyl group having 3 to 10 carbon atoms, and R ⁶ is a single bond, a methylene, a linear or branched alkylene group having 2 to 6 carbon atoms, or the general formula, a group represented by C (O) XR ^8, X is oxygen, sulfur, or NH group shown, R ⁸ represents a methylene, a linear or branched alkylene group having 2 to 6 carbon atoms, R ⁷ is small C1-C12 linear or branched alkyl group in which at least one hydrogen atom is substituted with a fluorine atom, or carbon number having an alicyclic structure in which at least one hydrogen atom is substituted with a fluorine atom 1 to 12 alkyl groups)   The photoresist pattern formation method of Claim 1 or 2 in which the said resin (A) contained in the said radiation sensitive resin composition contains the repeating unit containing a lactone structure.

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