JP5267093B2 - Upper layer film forming composition, upper layer film and pattern forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an upper layer film-forming composition to be used for an immersion lithography method, the composition capable of improving a depth of focus and giving a good pattern, and to provide an upper layer film obtained from the upper layer film-forming composition, and a pattern forming method using the upper layer film. <P>SOLUTION: The upper layer film-forming composition to be used for forming an upper layer film on the surface of a photoresist film contains: a resin component (A) that dissolves in a developing solution for developing the photoresist film; and an amide group-containing compound (B). <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

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

  In the manufacture of semiconductor elements, miniaturization of patterns formed on a substrate is required in order to increase the density of devices. In order to meet this requirement, it is desired to further increase the resolution of the exposure apparatus. As one of means for realizing the higher resolution, a liquid immersion area is formed on the substrate, and the liquid immersion area is formed. An immersion exposure method has been devised in which a substrate is exposed through a region of liquid (see Patent Document 1).

  In the immersion exposure method, an immersion upper layer film is usually used for the purpose of suppressing eluate in the photoresist film, preventing defects in the photoresist, and increasing the scanning speed (see Patent Documents 2 to 5). ).

Further, in the immersion exposure method, the numerical aperture (NA) of the apparent lens is increased. However, when the NA is increased, the resolution is improved, but there is a problem that the depth of focus (DOF) is lowered.
Japanese Patent Laid-Open No. 11-176727 JP 2005-268382 A WO2006 / 035790 WO2005 / 069076 WO2007 / 049637

  The present invention relates to an upper layer film-forming composition used in an immersion exposure method, which can improve the depth of focus and obtain a good pattern, and the upper layer film-forming composition It is an object of the present invention to provide an upper layer film obtained from a product and a pattern forming method using the upper layer film.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that the above-mentioned problems can be achieved by the upper layer film-forming composition shown below, and have completed the present invention. That is, according to the present invention, the following upper layer film-forming composition and the like are provided.

[1] solution in immersion exposure, an upper layer film forming composition used to form the upper layer film on the surface of the photoresist film, the composition includes a resin component have a sulfonic acid group (A) An upper layer film-forming composition containing an amide group-containing compound (B).

[2] The upper layer film-forming composition according to [1], wherein the amide group-containing compound (B) is an Nt-butoxycarbonyl group-containing amino compound.

[3] The upper layer film-forming composition according to [1] or [2], wherein the resin component (A) contains a resin having a group represented by the following formula (1).

(In the formula, “*” indicates a bond)

[ 4 ] An upper film obtained from the upper film-forming composition according to any one of [1] to [ 3 ].

[ 5 ] (i) a step of applying a photoresist on the substrate to form a photoresist film, (ii) a step of forming the upper layer film according to [4] above on the photoresist film, and (iii) Forming a resist pattern by irradiating the photoresist film and the upper layer film with radiation through a mask having a predetermined pattern through an immersion medium and then developing the pattern.

  By using the upper layer film-forming composition of the present invention, the depth of focus can be improved in the immersion exposure method, and a good pattern can be obtained.

  BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out the present invention will be described below, but the present invention is not limited to the following embodiment, and is based on the ordinary knowledge of those skilled in the art without departing from the gist of the present invention. It should be understood that modifications and improvements as appropriate to the following embodiments also fall within the scope of the present invention.

[1] Upper layer film-forming composition:
One embodiment of 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, which is dissolved in a developer for developing the photoresist film. Containing the resin component (A) and the amide group-containing compound (B).

[1-1] Resin component (A):
The resin component (A) contained in the upper layer film-forming composition of the present embodiment is a component composed of a resin that dissolves in a developer for developing the photoresist film.

  The resin component (A) preferably contains a resin having a sulfonic acid group. The resin having a sulfonic acid group has a sulfonic acid group by including a repeating unit having a sulfonic acid group.

  Preferred examples of the monomer for deriving a repeating unit having a sulfonic acid group include vinyl sulfonic acid, 2-acryloylamino-2-methyl-1-propanesulfonic acid, allyl sulfonic acid, and 4-vinyl-1-benzene. Examples include sulfonic acid, sulfoethyl acrylate, sulfobutyl acrylate, sulfoethyl methacrylate, sulfobutyl methacrylate, and compounds of the following formula. Of these sulfonic acid monomers, vinyl sulfonic acid and allyl sulfonic acid are particularly preferred.

  The resin component (A) preferably also contains a resin having a group represented by the following formula (1).

(In the formula, “*” indicates a bond)

  The resin having a group represented by the formula (1) has the formula (1) by including a repeating unit having the formula (1).

  The resin having the formula (1) has both water repellency and solubility in an alkaline aqueous solution, can exhibit water repellency and increase the scanning speed, and can make a photoresist film into an existing alkaline developer. It can be soluble.

  Preferred examples of the monomer for deriving the repeating unit having the formula (1) include methacrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester and Mention may be made of the compounds of the formula.

  The resin component (A) may be composed of a resin containing both a repeating unit having a sulfonic acid group and a repeating unit having the formula (1), or a resin containing a repeating unit having a sulfonic acid group, A resin containing a repeating unit having the formula (1) may be blended.

  The resin component (A) contains a resin containing a repeating unit represented by at least one selected from the group consisting of the following general formulas (2-1), (2-2), and (2-3). preferable. By including such a repeating unit, the resin component (A) contains an alkali-soluble group. Therefore, the solubility of the upper layer film formed by the upper layer film forming composition of the present embodiment in the developer is extremely high. There is an advantage of being good.

(In the general formulas (2-1), (2-2), and (2-3), R ¹ represents hydrogen, a methyl group, or a trifluoromethyl group, and R ² , R ^3, and R ⁴ are independent of each other. In addition, a single bond, methylene, a linear or branched alkylene group having 2 to 6 carbon atoms, a group in which a hydrogen atom of a linear or branched alkylene group having 2 to 6 carbon atoms is substituted with a fluorine atom, or A C 4-12 alicyclic alkylene group, wherein R ⁵ is a C 1-10 linear or branched alkyl group in which at least one hydrogen atom is substituted with a fluorine atom, or C 3 10 to 10 alicyclic alkyl groups)

R ² and R ⁴ in the general formulas (2-1) and (2-3) are a single bond, methylene, a linear or branched alkylene group having 2 to 6 carbon atoms, or 4 to 12 carbon atoms. Of the alicyclic alkylene group. Examples of the linear or branched alkylene group having 2 to 6 carbon atoms or the alicyclic alkylene group having 4 to 12 carbon atoms include a methylene group, an ethylene group, a 1,3-propylene group, and 1, Propylene group such as 2-propylene group, tetramethylene group, pentamethylene group, hexamethylene group, heptamethylene group, octamethylene group, nonamethylene group, decamethylene group, undecamethylene group, dodecamethylene group, tridecamethylene group, tetra Decamethylene group, pentadecamethylene group, hexadecamethylene group, heptacamethylene group, octadecamethylene group, nonacamethylene 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- Styrene group, methylidene group, ethylidene group, propylidene group, saturated chain hydrocarbon group such as 2-propylidene group, cyclobutylene group such as 1,3-cyclobutylene group, 1,3-cyclopentylene group, etc. Monocyclic hydrocarbons such as C3-C10 cycloalkylene groups such as cyclopentylene groups, cyclohexylene groups such as 1,4-cyclohexylene groups, and cyclooctylene groups such as 1,5-cyclooctylene groups 2-4 ring carbon number such as a ring group, a norbornylene group such as 1,4-norbornylene group or 2,5-norbornylene group, an adamantylene group such as 1,5-adamantylene group, 2,6-adamantylene group, etc. Examples thereof include bridged cyclic hydrocarbon ring groups such as 4 to 30 hydrocarbon ring groups. Among the R ² and R ⁴ linear or branched alkylene groups having 2 to 6 carbon atoms or the alicyclic alkylene groups having 4 to 12 carbon atoms, carbonization including a 2,5-norbornylene group. A hydrogen group, 1,2-ethylene group and propylene group are preferred.

In the case where R ² and R ⁴ contain a divalent aliphatic cyclic hydrocarbon group, a bistrifluoromethyl-hydroxy-methyl group (—CF ₃ —C (OH) —CF ₃ group) and the above divalent group It is preferable to arrange | position a C1-C4 alkylene group as a spacer between these aliphatic cyclic hydrocarbon groups.

As a monomer used in order to obtain the repeating unit represented by the general formulas (2-1) and (2-3), for example, (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. .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.

When R ³ in the general formula (2-2) is represented by “—Y—X—Y—”, specific examples of “X” include a single bond, a carbonyl group, a carbonyloxy group, an oxycarbonyl group, and the like. Can be mentioned. Specific examples of “Y” include a single bond, a methylene group, an alkylene group having 2 to 12 carbon atoms, and a group in which a hydrogen atom of an alkylene group having 2 to 12 carbon atoms is substituted with a fluorine atom. .

  Among specific examples of “Y”, the alkylene group having 2 to 20 carbon atoms includes, for example, a methylene group, an ethylene group, a propylene group such as a 1,3-propylene group or a 1,2-propylene group, a tetramethylene group, Pentamethylene 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, Icosalen 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, ethyl group, Ridene group, propylidene group, saturated chain hydrocarbon group such as 2-propylidene group, arylene group such as phenylene group and tolylene group, cyclobutylene group such as 1,3-cyclobutylene group, 1,3-cyclopentyl A cycloalkylene group having 3 to 10 carbon atoms such as a cyclopentylene group such as a lenylene group, a cyclohexylene group such as a 1,4-cyclohexylene group, and a cyclooctylene group such as a 1,5-cyclooctylene group. Examples include cyclic hydrocarbon ring groups, norbornylene groups such as 1,4-norbornylene group or 2,5-norbornylene group, adamantylene groups such as 1,5-adamantylene group, 2,6-adamantylene group, and the like. it can.

Examples of the monomer used to obtain the repeating unit represented by the general formula (2-2) include (meth) acrylic acid and bicyclo [2.2.1] hept-5-en-2- Ylmethanecarboxylic acid, 2-bicyclo [2.2.1] hept-5-enecarboxylic acid, 4-tricyclo [5.2.1.0 ^2,6 ] dec-8-enecarboxylic acid, tricyclo [5. 2.1.0 ^2,6 ] dec-8-en-4-ylmethanecarboxylic acid, bicyclo [2.2.1] hept-5-en-2-ylmethanecarboxylic acid, and the like.

R ⁵ in the general formula (2-3) is 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 a fat having 3 to 10 carbon atoms. It represents a cyclic alkyl group. Examples of these alkyl groups include a monofluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a 2,2,2-trifluoroethyl group, a perfluoroethyl group, and the like. A fluoromethyl group and the like are preferable.

  As a monomer used in order to obtain the repeating unit represented by the general formula (2-3), for example, (((trifluoromethyl) sulfonyl) amino) ethyl-1-methacrylate, 2-((( Examples thereof include trifluoromethyl) sulfonyl) amino) ethyl-1-acrylate, a compound represented by the following formula, and the like.

  When the resin constituting the resin component (A) includes a repeating unit represented by at least one selected from the group consisting of the general formulas (2-1), (2-2), and (2-3), The ratio of the total amount of these repeating units is preferably 50 to 99 mol%, more preferably 80 to 95 mol%, based on all the repeating units of the resin constituting the resin component (A). . If the ratio is less than 50 mol%, sufficient solubility in a developer may not be maintained. On the other hand, when the ratio is more than 99 mol%, the resist shape may be deteriorated.

  For the resin constituting the resin component (A) contained in the upper layer film-forming composition of this embodiment, other radical polymerizable monomers are used for the purpose of controlling the molecular weight of the resin, the glass transition point, the solubility in a solvent, and the like. A repeating unit derived from a monomer (hereinafter sometimes referred to as “other repeating unit”) or a structural unit derived from an acid-dissociable group-containing monomer can be contained.

  Examples of the monomer used to obtain the other repeating unit include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, and 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, methoxy Propylene 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 (meta ) Acrylate, 1-methyl-1-cyclopentyl (meth) acrylate, 1-ethyl-1-cyclopentyl (meth) acrylate, 1-propyl-1-cyclopentyl (meth) acrylate, 1-butyl-1-cyclopentyl (meth) acrylate , - 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 and diethyl itaconate; (meth) acrylic acid aryl esters such as phenyl (meth) acrylate and benzyl (meth) acrylate; styrene, α-methylstyrene, m-methylstyrene, Aromatic vinyls such as p-methylstyrene, vinyltoluene and p-methoxystyrene, nitrile group-containing radical polymerizable monomers such as acrylonitrile and methacrylonitrile; amide bond-containing radical polymerizable monomers such as acrylamide and methacrylamide Body; fatty acid vinyls such as vinyl acetate; chlorine-containing radical polymerizable monomers such as vinyl chloride and vinylidene chloride; conjugated diolefins such as 1,3-butadiene, isoprene and 1,4-dimethylbutadiene. Among these, (meth) acrylic acid alkyl ester, nitrile group-containing radical polymerizable monomer, amide bond-containing radical polymerizable monomer, and hydroxyl group-containing (meth) acrylic acid alkyl ester are preferable. In addition, these monomers can be used individually or in combination of 2 or more types.

  The proportion of the other repeating units is preferably 50 mol% or less, and 40 mol% or less, based on all the repeating units of the resin constituting the resin component (A) containing the other repeating units. More preferably. When the ratio is more than 50 mol%, the solubility in an alkaline aqueous solution used as a developer is lowered, so that it is difficult to remove the upper layer film, and a residue may be formed on the resist after development.

[1-3: Manufacturing method of resin constituting resin component (A)]
The production method of the resin constituting the resin component (A) is not particularly limited, and the resin constituting the resin component (A) can be used in a polymerization solvent in the presence of an appropriate initiator or chain transfer agent. One or more radical polymerizable monomers and other monomers used for obtaining other repeating units (hereinafter, these monomers are collectively referred to as “to produce a resin constituting the resin component (A)”). And the like may be referred to as "monomers used in the above".

  Examples of the initiator include 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2′-azobis ( 2-methylpropionate), 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis [N- ( 2-propenyl) -2-methylpropionamide], 1-[(cyano-1-methylethyl) azo] formamide, 2,2′-azobis (N-butyl-2-methylpropionamide), 2,2′- Azo compounds such as azobis (N-cyclohexyl-2-methylpropionamide), 2,2′-azobisisobutyronitrile, 2,2′-azobisdimethylvaleronitrile;

  Examples thereof include di-tert-butyl peroxide, tert-butyl hydroperoxide, benzoyl peroxide, lauroyl peroxide, potassium persulfate, t-butyl peroxypivalate, t-butyl hydro-oxide, and dicumyl peroxide. Among these, dimethyl 2,2'-azobis (2-methylpropionate) and 2,2'-azobisisobutyronitrile are preferable.

  Examples of the chain transfer agent include halogen compounds such as carbon tetrachloride and carbon tetrabromide, alcohols such as isopropyl alcohol and isobutyl alcohol; 2-methyl-1-butene, 2,4-diphenyl-4-methyl-1 -Olefins such as pentene; ethanethiol, butanethiol, dodecanethiol, mercaptoethanol, mercaptopropanol, methyl mercaptopropionate, ethyl mercaptopropionate, mercaptopropionic acid, thioglycolic acid, ethyl disulfide, 2-butyl disulfide, 2- Sulfur-containing compounds such as hydroxyethyl disulfide, thiosalicylic acid, thiophenol, thiocresol, benzyl mercaptan, phenethyl mercaptan; and α-methylstyrene dimer.

  Examples of the polymerization solvent used when producing the resin constituting the resin component (A) include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, ethylene glycol, diethylene glycol, and propylene glycol. Alcohols such as tetrahydrofuran; cyclic ethers such as 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 Alkyl ethers of polyhydric alcohols such as rumonomethyl 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 and propylene glycol monomethyl ether acetate Kind;

  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 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. Among these, cyclic ethers, alkyl ethers of polyhydric alcohols, alkyl ether acetates of polyhydric alcohols, ketones, esters and the like are preferable.

  As a method for radical polymerization, for example, the monomer, initiator, chain transfer agent, and polymerization solvent used for producing the resin constituting the resin component (A) are all charged in the reaction vessel, and then polymerization is performed. After filling the reaction vessel with at least one of the polymerization method to be started and the monomer, initiator, chain transfer agent, and polymerization solvent used for producing the resin constituting the resin component (A), etc. A polymerization method in which the above components are added dropwise for polymerization. The polymerization conditions for radical polymerization can be performed under conventionally known conditions. For example, the reaction is preferably performed at 50 to 100 ° C. for 2 to 10 hours.

  The weight average molecular weight of the resin constituting the resin component (A) (hereinafter sometimes referred to as “Mw”) is preferably 2,000 to 100,000, respectively, and is 2,500 to 50,000. More preferably, it is particularly preferably 3,000 to 20,000. If the Mw of the resin constituting the resin component (A) is less than 2,000, the water resistance and mechanical properties as the upper layer film may be significantly reduced. On the other hand, if it exceeds 100,000, there is a possibility that the solubility in a solvent described later is remarkably lowered. Further, the ratio (Mw / Mn) of Mw of the resin constituting the resin component (A) to the number average molecular weight (hereinafter sometimes referred to as “Mn”) is preferably 1 to 5, 3 is more preferable. In the present specification, “weight average molecular weight” and “number average molecular weight” are values in terms of polystyrene measured by gel permeation chromatography (GPC).

  In the polymerization reaction liquid obtained by radical polymerization, the smaller the impurities such as halogen and metal, the better. By reducing the impurities, the coating property of the upper layer film-forming composition of this embodiment and the uniform solubility of the upper layer film in the alkaline developer are further improved. Examples of the purification method of the resin constituting the resin component (A) include chemical purification methods such as water washing and liquid-liquid extraction, and these chemical purification methods and physical purification methods such as ultrafiltration and centrifugation. And the like.

  By including the resin component (A) in the upper layer film-forming composition of this embodiment, it is possible to form a stable upper layer film (protective film) against a medium (immersion liquid) such as water. Therefore, it can be suitably used for immersion exposure. Further, it is possible to form an upper layer film that can be dissolved in a developer used for forming a resist pattern. Here, “stable with respect to the medium (immersion liquid)” means that the change rate of the film thickness measured by the following [stability evaluation test] is within 3% of the initial film thickness. It shall be.

[Stability evaluation test]:
Using a coater / developer (1) (trade name: CLEAN TRACK ACT8, manufactured by Tokyo Electron Ltd.), a resin component (A) dissolved in a solvent described later as an upper layer film-forming composition on an 8-inch silicon wafer Spin coating is performed and pre-baking (PB) is performed at 90 ° C. for 60 seconds to form an upper film having a thickness of 90 nm. The film thickness of this upper layer film is measured using an optical interference type film thickness measuring device (trade name: Lambda Ace VM-2010, manufactured by Dainippon Screen Mfg. Co., Ltd.). In addition, the film thickness at this time is called initial film thickness. Next, after the ultrapure water is discharged from the rinse nozzle of the coater / developer (1) for 60 seconds onto the surface of the wafer on which the upper layer film is formed, it is shaken off at a rotational speed of 4000 rpm for 15 seconds and spin-dried. Thereafter, the film thickness of the upper layer film is measured again with the optical interference film thickness measuring apparatus, and the change ratio of the film thickness with respect to the initial film thickness is calculated. If the calculated change ratio is within 3%, it is evaluated as “stable with respect to the medium (immersion liquid)”. Further, “being soluble in the developer” means that when an alkaline aqueous solution is used as the developer, there is no residue of the upper layer film on the resist pattern, and the upper layer film is removed. In addition, the presence or absence of a residue is performed visually.

  As described above, the resin component (A) contained in the upper layer film-forming composition of the present embodiment hardly dissolves in a medium such as water, and is a developer during development after radiation irradiation. It consists of an alkali-soluble resin that can be dissolved in an alkaline aqueous solution.

  The upper film formed by the upper film forming composition of the present embodiment prevents the photoresist film and a medium such as water from coming into direct contact during immersion exposure, and the photoresist formed by the penetration of the medium. It is difficult to deteriorate the lithography performance of the film, and it is possible to prevent the lens of the projection exposure apparatus from being contaminated by components eluted from the photoresist film.

[1-2] Amide group-containing compound (B):
The upper layer film-forming composition of this embodiment contains an amide group-containing compound (B). Examples of the amide group-containing compound (B) include 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-butoxycarbonyl) -2-pyrrolidinemethanol, (R)-(+)-1- (t-butoxycarbonyl) -2-pyrrolidinemethanol, Nt-butoxycarbonyl- 4-hydroxypiperidine, Nt-butoxycarbonylpyrrolidine, Nt-butoxy Rubonylpiperazine, Nt-butoxycarbonylpiperidine, 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, N In addition to Nt-butoxycarbonyl group-containing amino compounds such as -t-butoxycarbonyl-2-phenylbenzimidazole, formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N Examples include -dimethylacetamide, propionamide, benzamide, pyrrolidone, N-methylpyrrolidone, N-acetyl-1-adamantylamine, and isocyanuric acid tris (2-hydroxyethyl). Nt-butoxycarbonyl group-containing amino compounds are preferred.

  The compounding amount of the amide group-containing compound (B) is preferably 0.05 parts by mass or more and 10 parts by mass or less, more preferably 0.05 parts by mass or more and 5 parts by mass with respect to 100 parts by mass of the resin component (A). Hereinafter, it is particularly preferably 0.05 parts by mass or more and 3 parts by mass or less.

[1-3] Solvent (C):
It is preferable to add a solvent (C) to the upper layer film-forming composition of this embodiment for the purpose of dissolving the resin component (A) and the amide group-containing compound (B). As the solvent, it is preferable to use a solvent that hardly deteriorates the lithography performance, such as causing intermixing with the photoresist film when applied on the photoresist film.

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

  Examples of the monohydric alcohols include 1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, 2-pentanol, 3-pentanol, tert-amyl alcohol, and 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- Monovalent compounds having 4 to 10 carbon atoms such as butanol, 3-methyl-3-pentanol, 4-methyl-1-pentanol, 4-methyl-2-pentanol, 4-methyl-3-pentanol, cyclohexanol, etc. Examples include alcohol.

  Examples of the polyhydric alcohols include ethylene glycol and propylene glycol; and examples of polyhydric alcohol alkyl ethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and 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 .; as alkyl ether acetates of polyhydric alcohol, ethylene glycol ethyl ether acetate, diethylene glycol Call ethyl ether acetate, propylene glycol ethyl ether acetate, and the like propylene glycol monomethyl ether acetate.

  Examples of the ethers 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, cyclohexyl propyl ether, cyclohexyl-2- Propyl ether, cyclopentyl butyl ether, cyclopentyl-te t- butyl ether, cyclohexyl ether, and a cyclohexyl -tert- butyl ether. Examples of cyclic ethers include tetrahydrofuran and dioxane.

  Examples of the higher hydrocarbons include decane, dodecane, and undecane. Examples of aromatic hydrocarbons include benzene, toluene, xylene and the like. Examples of ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, 4-hydroxy-4-methyl-2-pentanone, diacetone alcohol, and the like. Examples of the esters include ethyl acetate, butyl acetate, ethyl 2-hydroxypropionate, methyl 2-hydroxy-2-methylpropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, Mention may be made of methyl 2-hydroxy-3-methylbutanoate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate and methyl 3-ethoxypropionate.

  Among these, monohydric alcohols, ethers, cyclic ethers, polyhydric alcohol alkyl ethers, polyhydric alcohol alkyl ether acetates, and higher hydrocarbons are preferable, alcohol having 4 to 10 carbon atoms, carbon number More preferred are alkyl ethers having 4 to 10 alkyl chains. These can be used alone or in combination of two or more.

  It is particularly preferable to contain at least one selected from a solvent (C-i) which is an alcohol having 4 to 10 carbon atoms and a solvent (C-ii) which is an alkyl ether having an alkyl chain having 4 to 10 carbon atoms.

[1-4] Additive:
In addition, a surfactant or the like can be added to the upper layer film-forming composition of the present embodiment for the purpose of improving coating properties, antifoaming properties, leveling properties and the like.

  Examples of commercially available surfactants include BM-1000 and BM-1100 (all manufactured by BM Chemie), MegaFuck F142D, F172, F173, and F183 (all Dainippon, Japan). Ink Chemical Industries Co., Ltd.), Florard FC-135, FC-170C, FC-430, FC-431 (above, manufactured by Sumitomo 3M), Surflon S-112, S-113, S-131, S-141, S-145 (made by Asahi Glass Co., Ltd.), SH-28PA, -190, -193, SZ-6032, SF-8428 (made by Toray Dow Corning Silicone), Emulgen A- Fluorosurfactants such as 60, 104P, and 306P (above, manufactured by Kao Corporation) can be exemplified. 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 a resin component (A) and an amide group containing compound (B).

[2] Pattern formation method:
Next, an embodiment of the pattern forming method of the present invention will be described. The pattern forming method of this embodiment includes (i) a step of applying a photoresist on a substrate to form a photoresist film, (ii) a step of forming an upper layer film on the photoresist film, and (iii) the step of The photoresist film and the upper layer film are irradiated with radiation through a mask having a predetermined pattern via an immersion medium, and then developed to form a resist pattern, thereby forming a resist pattern.

  In the step of forming a photoresist film by applying a photoresist on the substrate, for example, a silicon wafer, a wafer coated with aluminum, or the like can be used as the substrate. In order to maximize the potential of the resist film, an organic or inorganic antireflection film is formed on the substrate to be used, as disclosed in, for example, Japanese Patent Publication No. 6-12452. I can leave.

  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.

  When using the upper layer film formed of the composition of the present invention, a positive resist is particularly preferable. In a chemically amplified positive resist, an acid-dissociable organic group in the polymer is dissociated by the action of an acid generated from an acid generator by exposure to generate, for example, a carboxyl group. The solubility in an alkali developer is increased, and the exposed portion is dissolved and removed by the alkali developer to obtain a positive resist pattern.

  The photoresist film is prepared by dissolving a resin for forming a photoresist film in a suitable solvent at a solid content concentration of, for example, 0.1 to 20% by weight, and then filtering the solution by, for example, a filter having a pore diameter of about 30 nm. The resist solution is prepared by applying it onto a substrate by an appropriate application method such as spin coating, cast coating, roll coating, etc., and pre-baking (hereinafter referred to as “PB”) to volatilize the solvent. To do. In this case, a commercially available resist solution can be used as it is.

  The step of forming the upper layer film on the photoresist film using the upper layer film-forming composition is performed by applying the upper layer film-forming composition of the present invention on the photoresist film and usually firing again. It is a process of forming the upper layer film of the invention. This step is a step of forming an upper layer film for the purpose of protecting the photoresist film and preventing contamination of the lens of the projection exposure apparatus caused by elution of components contained in the resist from the photoresist film to the liquid. is there.

  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. In the present invention, any of the pre-baking after the application of the resist solution and the baking after the application of the upper layer film forming composition solution may be omitted for simplification of the process.

  The step of forming a resist pattern by irradiating the photoresist film and the upper layer film with water through a mask having a predetermined pattern using water as a medium and then developing is performed by immersion exposure and baking at a predetermined temperature. This is a step of developing after performing.

  The pH of water filled between the photoresist film and the upper film can be adjusted. In particular, pure water is preferred.

  The radiation used for immersion exposure depends on the photoresist film used and the combination of the photoresist film and the upper layer film for immersion, for example, visible rays; ultraviolet rays such as g rays and i rays; Various types of radiation such as ultraviolet rays; X-rays such as synchrotron radiation; and charged particle beams such as electron beams can be selectively used. In particular, an ArF excimer laser (wavelength 193 nm) or a KrF excimer laser (wavelength 248 nm) is preferable.

  In order to improve the resolution, pattern shape, developability, etc. of the resist film, it is preferable to perform baking (hereinafter referred to as “PEB”) after exposure. The baking temperature is appropriately adjusted depending on the resist used and the like, but is usually about 30 to 200 ° C., preferably 50 to 150 ° C.

  Next, the photoresist film is developed with a developer and washed to form a desired resist pattern. In this case, the upper film for immersion according to the present invention does not need to be subjected to a separate peeling step, and is completely removed during development or washing after development. This is one of the important features of the present invention.

  Examples of the developer used for forming the resist pattern in the present invention include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, diethylamine, and di-n-. Propylamine, triethylamine, methyldiethylamine, dimethylethanolamine, triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene And an alkaline aqueous solution in which 1,5-diazabicyclo- [4.3.0] -5-nonane and the like are dissolved. In addition, an appropriate amount of a water-soluble organic solvent, for example, an alcohol such as methanol or ethanol, or a surfactant can be added to these developers. In the case where development is performed using the alkaline aqueous solution, it is usually washed with water after development.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.

  Hereinafter, the embodiment of the present invention will be described more specifically with reference to examples. In the description of Examples, “part” and “%” are based on mass unless otherwise specified.

[1] Synthesis of resin component (A) used in composition for upper layer film for liquid immersion As the resin component (A), a stable film can be formed in water at the time of irradiation with radiation. Resin (A-1)-(A-4) which melt | dissolves was synthesize | combined by the method shown below.

Synthesis Example 1 Synthesis of Resin (A-1) 2-Methacryloyloxyethyl hexahydrophthalate: 46.95 g (85 mol%) and initiator 2,2′-azobis- (methyl 2-methylpropionate) : A monomer solution in which 6.91 g was dissolved in 100 g of isopropanol was prepared.

  Meanwhile, 50 g of isopropanol was charged into a 500 ml three-necked flask equipped with a thermometer and a dropping funnel, and purged with nitrogen for 30 minutes. After purging with nitrogen, the inside of the flask was heated to 80 ° C. while stirring with a magnetic stirrer.

  And the monomer solution prepared beforehand was dripped over 2 hours using the dropping funnel. After completion of the dropping, the reaction was further continued for 1 hour, and 10 g of an isopropanol solution of vinylsulfonic acid: 3.05 g (15 mol%) was added dropwise over 30 minutes. Thereafter, the reaction was further performed for 1 hour, and then cooled to 30 ° C. or lower to obtain a copolymer solution.

  Next, the obtained copolymer solution was concentrated to 150 g, and then transferred to a separatory funnel. The separatory funnel was charged with 50 g of methanol and 600 g of n-hexane to carry out separation and purification. After separation, the lower layer solution was recovered. This lower layer solution was diluted with isopropanol to 100 g, and again transferred to a separatory funnel. Thereafter, 50 g of methanol and 600 g of n-hexane were added to the separatory funnel, separation and purification were performed, and the lower layer liquid was recovered after separation. The recovered lower layer solution was replaced with 4-methyl-2-pentanol, and the total amount was adjusted to 250 g. After the adjustment, 250 g of water was added for separation and purification. After separation, the upper layer liquid was recovered. The recovered upper layer liquid was replaced with 4-methyl-2-pentanol to obtain a resin solution. The solid concentration of the sample (resin solution) after the 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, it 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 composition solution for the upper layer film and the yield calculation.

  Mw of the copolymer contained in the obtained resin solution was 11060, Mw / Mn was 1.55, and the yield was 75%. Moreover, the content rate of the repeating unit derived from 2-methacryloyloxyethyl hexahydrophthalate contained in this copolymer and the repeating unit derived from vinylsulfonic acid was 95: 5 (mol%). . This copolymer is referred to as “resin (A-1)”.

(Synthesis Example 2) Synthesis of Resin (A-2) 2-Methacryloyloxyethyl hexahydrophthalate: 50.0 g and initiator (2,2′-azobis- (methyl 2-methylpropionate)): 3. A monomer solution in which 24 g was dissolved in 50 g of isopropanol was prepared.

  On the other hand, 100 g of isopropanol 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.

  And the monomer solution prepared beforehand was dripped over 3 hours using the dropping funnel. After completion of dropping, the reaction was further continued for 3 hours, and then cooled to 30 ° C. or lower to obtain a polymerization solution. The obtained polymerization solution was added to 2400 g of water, and the precipitate was collected and dried for 24 hours at room temperature and under reduced pressure to obtain a resin powder. The resin powder was dissolved in 1000 g of methanol, transferred to a separatory funnel, purified by adding 2000 g of n-hexane and 400 g of water, and the lower layer was recovered. Thereafter, the lower layer was concentrated to 100 g and substituted with 4-methyl-2-pentanol to obtain a resin solution. The solid concentration of the sample (resin solution) after the 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, it 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 composition solution for the upper layer film and the yield calculation.

  Mw of the resin contained in the obtained resin solution was 9760, Mw / Mn was 1.31, and the yield was 50%. This is designated as resin (A-2).

(Synthesis Example 3) Synthesis of Resin (A-3) 2-Methacryloyloxyethyl hexahydrophthalate: 48.15 g (95 mol%) and 2-acryloylamino-2-methyl-1-propanesulfonic acid: 1. A monomer solution was prepared by dissolving 85 g (5 mol%) and initiator 2,2′-azobis- (methyl methyl 2-methylpropionate): 3.28 g in 50 g of isopropanol.

  On the other hand, 100 g of isopropanol 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.

  And the monomer solution prepared beforehand was dripped over 3 hours using the dropping funnel. After completion of dropping, the reaction was further continued for 3 hours, and then cooled to 30 ° C. or lower to obtain a polymerization solution.

  Next, the obtained polymerization solution was added to 2400 g of water, and then the precipitate was collected and dried for 24 hours at room temperature under reduced pressure to obtain a resin powder. The resin powder was dissolved in 1000 g of methanol, transferred to a separatory funnel, purified by adding 2000 g of n-hexane and 400 g of water, and the lower layer was recovered. Thereafter, the lower layer was concentrated to 100 g and substituted with 4-methyl-2-pentanol to obtain a resin solution. The solid concentration of the sample (resin solution) after the 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, it 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 composition solution for the upper layer film and the yield calculation.

  Mw of the copolymer contained in the obtained resin solution was 9260, Mw / Mn was 1.35, and the yield was 30%. The content of the repeating unit derived from 2-methacryloyloxyethyl hexahydrophthalate and the repeating unit derived from 2-acryloylamino-2-methyl-1-propanesulfonic acid contained in this copolymer is 97: 3 (mol%). This copolymer is referred to as “resin (A-3)”.

(Synthesis Example 4) Synthesis of Resin (A-4) A mixed solution in which 25.0 g of 2,2-azobis (methyl 2-methylisopropionate): 25.0 g was dissolved in 25.0 g of methyl ethyl ketone was prepared.

  On the other hand, in a 2000 ml three-necked flask equipped with a thermometer and a dropping funnel, methacrylic acid (1,1,1,3,3,3-hexafluoro-2-propyl) ester: 104.6 g, methacrylic acid (1 , 1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester: 195.4 g and methyl ethyl ketone: 575.0 g were charged and purged with nitrogen for 30 minutes. After purging with nitrogen, the inside of the flask was heated to 80 ° C. while stirring with a magnetic stirrer.

  And the prepared mixture solution was dripped over 5 minutes using the dropping funnel, and it was made to age | cure | ripen for 360 minutes. Then, it cooled to 30 degrees C or less, and obtained the copolymer liquid.

  Next, the obtained copolymer solution was concentrated to 600 g and then transferred to a separatory funnel. To this separatory funnel, 193 g of methanol and 1542 g of n-hexane were added for separation and purification. After separation, the lower layer solution was recovered. 117 g of methyl ethyl ketone and 1870 g of n-hexane were added to the recovered lower layer solution, and separation and purification were performed. After separation, the lower layer solution was recovered. Further, 93 g of methanol, 77 g of methyl ethyl ketone, and 1238 g of n-hexane were added to the recovered lower layer solution, followed by separation and purification. After separation, the lower layer solution was recovered. The recovered lower layer solution was replaced with 4-methyl-2-pentanol, this solution was washed with distilled water, and replaced with 4-methyl-2-pentanol again to obtain a resin solution. The solid concentration of the sample (resin solution) after the 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, it 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 yield calculation.

  Mw of the copolymer contained in the obtained resin solution was 10200, Mw / Mn was 1.65, and the yield was 65%. Further, repeating units derived from methacrylic acid (1,1,1,3,3,3-hexafluoro-2-propyl) ester contained in this copolymer, and methacrylic acid (1,1,1-trimethyl) The content of repeating units derived from (fluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester was 39.5: 60.5 (mol%). This copolymer is referred to as “resin (A-4)”.

[2] Preparation of composition for forming upper layer film for immersion (Example 1)
As resin component (A), 95 parts of resin (A-1), 5 parts of resin (A-2), 0.05 part of Nt-butoxycarbonyl-4-hydroxypiperidine (B-1), solvent (4 carbon atoms) To 100 alcohol), 100 parts of 4-methyl-2-pentanol ("solvent (C-1)" in Table 1) was mixed, stirred for 2 hours, and then filtered through a filter having a pore size of 200 nm. A composition solution for the upper layer film of Example 1 was prepared.

(Examples 2-8 and Comparative Examples 1-4)
Except having used the composition shown in Table 1, the composition solution for each upper layer film of Examples 2-8 and Comparative Examples 1-4 was prepared by the method similar to Example 1. FIG.

In addition, the detail of each component used in a table | surface is as follows.
B-1: Nt-butoxycarbonyl-4-hydroxypiperidine B-2: Nt-butoxycarbonyldicyclohexylamine BR-1: triethylamine C-1: 4-methyl-2-pentanol

[3] Preparation of Radiation Sensitive Resin Composition (Reference Example 1) Synthesis of Resin for Radiation Sensitive Resin Composition 53.93 g (50 mol%) of a compound for constituting the following repeating unit (M-1), 35.38 g (40 mol%) of the compound for constituting the repeating unit (M-2), 10.69 g (10 mol%) of the compound for constituting the repeating unit (M-3) shown below were added to 200 g of 2-butanone. And a monomer solution charged with 5.58 g of dimethyl 2,2′-azobis (2-methylpropionate) was prepared. On the other hand, 100 g of 2-butanone 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 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 (74 g, yield 74%).

The obtained copolymer has Mw of 6900 and Mw / Mn of 1.70. As a result of ¹³ C-NMR analysis, the repeating units (M-1), (M-2) and (M-3) The content was a copolymer of 53.0: 37.2: 9.8 (mol%), respectively, and the content of the repeating unit containing an acid dissociable group was 37.2 mol%. This was made into resin ((alpha) -1) for radiation sensitive resin compositions.

  In addition, the measurement and evaluation in the said synthesis example were performed in the following way. The same applies to each synthesis example in the subsequent stage.

<Mw and Mn>
Using a Tosoh GPC column (trade name “G2000HXL”; two, “G3000HXL”; one, “G4000HXL”; one) on a high-speed GPC device (model “HLC-8120”) manufactured by Tosoh Measurement was performed by gel permeation chromatography (GPC) using monodisperse polystyrene as a standard under the analysis conditions of 1.0 ml / min, elution solvent tetrahydrofuran, and column temperature of 40 ° C. Further, the degree of dispersion Mw / Mn was calculated from the measurement results.

< ^13C -NMR analysis>
The ¹³ C-NMR analysis of each polymer was measured using “JNM-EX270” manufactured by JEOL Ltd.

Reference Example 2 Preparation of Radiation Sensitive Resin Composition Resin for Radiation Sensitive Resin Composition (α-1): 100 parts, Triphenylsulfonium / Nonafluoro-n-butanesulfonate: 1.5 parts, 1- (4 -N-butoxynaphthalen-1-yl) tetrahydrothiophenium nonafluoro-n-butanesulfonate: 6 parts, R-(+)-(tert-butoxycarbonyl) -2-piperidinemethanol: 0.65 parts, propylene glycol Monomethyl ether acetate: 2400 parts were mixed and stirred for 2 hours, and then filtered through a filter having a pore size of 200 nm to prepare a radiation sensitive resin composition.

[4] Performance Evaluation of Examples The following various measurements and evaluations were performed on the upper layer film obtained using each of the upper layer film composition solutions prepared as described above. These results are shown in Table 1.

(4-1) Depth of focus (DOF)
Using a trade name “CLEAN TRACK ACT8” on an 8-inch silicon wafer, a composition for a lower antireflection film (trade name “ARC29A”, manufactured by Brewer Science Co., Ltd.) is spin-coated, and 205 ° C. × 60 seconds. By performing PB under the conditions, a 77 nm-thick coating film (lower antireflection film) was formed. The radiation-sensitive resin composition was spin-coated on the formed lower antireflection film, and PB was performed at 90 ° C. × 60 seconds to form a 120 nm-thick coating film (photoresist film).

  Thereafter, the upper layer film composition is spin-coated on the formed photoresist film, and PB (a condition of 90 ° C. × 60 seconds or a condition of 110 ° C. × 60 seconds) is performed to form a coating film having a thickness of 90 nm ( Upper layer film) was formed. 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. Then, PEB was performed under the condition of 105 ° C. × 60 seconds using a hot plate with the trade name “CLEAN TRACK ACT8”, and then paddle development (developer: 2.38% TMAH aqueous solution) was performed for 30 seconds using an LD nozzle. went. Next, after rinsing with ultrapure water, spin drying was performed by shaking off at 4000 rpm for 15 seconds. At this time, with respect to the formed resist pattern, an 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 an optimum exposure amount. For the measurement, a scanning electron microscope (trade name “S-9380”, manufactured by Hitachi Keiki Co., Ltd.) was used.

  Thereafter, a line-and-space pattern having a line width of 90 nm was observed with a scanning electron microscope (manufactured by Hitachi Keiki Co., Ltd., “S9260A”), and the depth of focus (DOF) was measured.

(4-2) Pattern Shape Using a method similar to the evaluation of the depth of focus (DOF), the cross-sectional shape at the best focus of the line-and-space pattern with a line width of 90 nm is scanned with a scanning electron microscope (model number “S-4200”). And manufactured by Hitachi Sokki Co., Ltd.). FIG. 1 is a cross-sectional view schematically showing the shape of a line and space pattern.

  Then, when 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 are measured, and 0.9 ≦ La / Lb ≦ 1.1 The case where “◯”, La / Lb <0.9, or La / Lb> 1.1 was evaluated as “x”.

  As is apparent from Table 1, the upper layer film-forming compositions of the present invention of Examples 1 to 8 are both excellent in DOF and pattern shape. On the other hand, in Comparative Examples 1 and 2 in which the amide group-containing compound (B) is not used, the DOF is shallow and the pattern shape is inferior. When triethylamine (BR-1) is used instead of the amide group-containing compound (B), the configuration of Comparative Example 3 has a good pattern shape but a shallow DOF. In the configuration of Comparative Example 4, the DOF is shallow and the pattern shape is inferior.

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

It is sectional drawing which shows the shape of a line and space pattern typically.

Explanation of symbols

1: substrate, 2: pattern.

Claims (5)

In the liquid immersion exposure, an upper layer film forming composition used to form the upper layer film on the surface of a photoresist film,
The composition, resin component have a sulfonic acid group (A) and the amide group-containing compound (B) and the upper layer film forming composition containing a.   The upper film-forming composition according to claim 1, wherein the amide group-containing compound (B) is an Nt-butoxycarbonyl group-containing amino compound. The upper film | membrane formation composition of Claim 1 or 2 in which the said resin component (A) contains resin which has group shown by following formula (1).

(In the formula, “*” indicates a bond) The upper film | membrane obtained from the upper film | membrane formation composition as described in any one of Claims 1-3 . (I) applying a photoresist on the substrate to form a photoresist film;
(Ii) forming an upper film according to claim 4 on the photoresist film;
(Iii) forming a resist pattern by irradiating the photoresist film and the upper layer film with radiation through a mask having a predetermined pattern through an immersion medium and then developing the pattern.

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