JP2010106118A - Polymer and photoresist composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polymer capable of giving a resist film having a large receding angle of water, and to provide a photoresist composition blended with the same. <P>SOLUTION: This polymer includes a structural unit derived from a monomer which has, in one molecule, at least two trifluoromethyl groups, a univalent unsaturated cyclic group expressed by formula (1) (wherein, A is a single bond, a methylene group, an isopropylidene group or an oxygen atom), and a hydroxy group. The photoresist composition includes a photoresist resin to change into alkali soluble by the action of an acid, an acid generating agent and the above polymer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polymer, particularly a polymer for blending in a photoresist composition, a photoresist composition containing the polymer, and the like.

  A photoresist composition is an organic material used in a lithography process for finely processing a semiconductor. For example, a composition described in Patent Document 1 is known. Such a photoresist composition is applied on a silicon wafer, exposed to light using a light source such as an ArF excimer laser, patterned, and then developed using an alkali developer to form a fine pattern. Can be formed.

  In recent years, an immersion exposure method has been developed and studied for use as a lithography process capable of finer patterning. In the immersion exposure method, exposure is performed in a state where the space between the projection lens of the semiconductor exposure apparatus and the silicon wafer is filled with ultrapure water, and patterning can be miniaturized without shortening the wavelength of the light source. Become.

In this immersion exposure method, defects caused by remaining water droplets after scanning are a serious problem. This defect is one of the defects characteristic to immersion exposure, and a defect is generated on the resist film by performing post-exposure baking with water droplets remaining. Non-Patent Document 1 describes that the number of defects due to remaining water droplets is related to the receding angle of water on the resist film, and it is possible to reduce defects due to remaining water droplets by increasing the receding angle. Has been.
JP 2001-209180 A K. Nakano et al., “Defectivity data taken with a full-field immersion exposure tool”, Presentation at the 2nd International Symposium on Immersion Lithography, Sep. 2005

  However, conventional resist films do not necessarily have a sufficient water receding angle, and there is a need for a photoresist composition that provides a resist film having a large water receding angle.

  In order to solve this problem, the present inventors diligently studied about a photoresist composition, and as a result, arrived at the inventions described in [1] to [5] below.

  [1] Containing a structural unit derived from a monomer having at least two trifluoromethyl groups, a monovalent unsaturated cyclic group represented by formula (1), and a hydroxyl group in one molecule. A polymer characterized by

(In the formula, A represents a single bond, a methylene group, an isopropylidene group or an oxygen atom.)
[2] The polymer according to [1], wherein the monomer is a compound represented by the formula (2).

(In the formula, A represents a single bond, a methylene group, an isopropylidene group or an oxygen atom. R represents an alkylene group having 1 to 12 carbon atoms. The methylene group in the alkylene group is substituted with an oxygen atom. The hydrogen atom in the alkylene group may be substituted with a fluorine atom.)
[3] The polymer according to [1], wherein the monomer is a compound represented by the formula (3).

[4] A photoresist composition comprising a photoresist resin that changes to alkali solubility by the action of an acid, an acid generator, and the polymer according to any one of [1] to [3].
[5] The proportions of the photoresist resin, the acid generator, and the polymer are 75 to 96.9 wt%, 0.1 to 20 wt%, and 3 to 5 wt%, respectively ( However, the total of these three components is 100% by weight). The photoresist composition according to [4].

  The photoresist composition containing the polymer of the present invention can provide a resist film having a large water receding angle.

  The polymer of the present invention contains a structural unit derived from a monomer having a specific structure. The monomer has at least two trifluoromethyl groups, a monovalent unsaturated cyclic group represented by the formula (1), and a hydroxyl group in one molecule. This monomer usually constitutes a polymer by addition polymerization of the unsaturated group in formula (1) representing the unsaturated cyclic group. Hereinafter, the monomer is also referred to as “monomer (1)”.

  In formula (1), A represents a single bond, a methylene group, an isopropylidene group or an oxygen atom. In the formula (1), the bonding position is not particularly limited, but from the viewpoint of availability, an unsaturated cyclic group having a bonding position shown in the following formula (1 ′) is preferable.

  As said monomer (1), the compound represented by following formula (2) is preferable.

  In formula (2), A represents a single bond, a methylene group, an isopropylidene group, or an oxygen atom as described above. R represents an alkylene group having 1 to 12 carbon atoms. The methylene group in the alkylene group may be substituted with an oxygen atom, and the hydrogen atom in the alkylene group may be substituted with a fluorine atom.

  As said monomer, the compound represented by the following formula | equation (3) is mentioned, for example.

  The polymer of the present invention may be a homopolymer of the monomer (1) or a copolymer of the monomer (1) and another acrylic monomer or methacrylic monomer. May be. Examples of the other monomer include a fluorine atom-containing acrylic acid ester or a fluorine atom-containing methacrylic acid ester.

  When the polymer is a copolymer, structural units derived from other monomers can be contained within a range in which the effects of the present invention can be achieved. Of the structural units constituting the polymer, 90 mol% or more It is preferable that the structural unit derived from the monomer (1) occupies. Most preferably, it is a homopolymer consisting only of structural units derived from the monomer (1).

  Although the molecular weight of the polymer of this invention is not specifically limited, Usually, the range of 700-100,000 is preferable at a weight average molecular weight, Preferably it is the range of 3000-20000.

  The method for producing the polymer is not particularly limited, and various polymerization methods can be used. Among them, the radical polymerization method is preferable. Specifically, first, each monomer to be polymerized and a radical polymerization initiator are sequentially added and dissolved in an organic solvent, and then the reaction solution is kept at a predetermined reaction temperature to obtain a target polymer. be able to.

The polymer can be obtained from Sumitomo Bakelite Co., Ltd. as DUVCOR A5100 series. The polymer of the present invention is a photoresist resin (specifically, for example, alkaline by the action of an acid). It is most preferable to use it as a polymer for blending with a photoresist resin, which is used by being added to a chemically amplified positive photoresist resin which changes into solubility. Moreover, since it has low affinity with water, it can also be used as an additive for addition to the composition for forming a water-repellent film.

  When the polymer of the present invention is used as a polymer to be added to a photoresist resin for addition to a photoresist resin that changes to alkali solubility by the action of an acid, an acid generator that generates an acid upon exposure. A photoresist composition can be comprised by mix | blending.

  The photoresist resin that can be preferably used with the polymer of the present invention will be described. The photoresist resin is preferably a resin containing (a) a structural unit having an acid-labile group in the side chain. More preferably, the resin further contains at least one selected from the group consisting of (i) a structural unit having a hydroxyl group in the side chain and (u) a structural unit having a lactone structure in the side chain. The resin may contain (d) a structural unit having a structure containing fluorine in the side chain.

  As the structural unit (a) having an acid labile group in the side chain, a structural unit represented by the formula (Ia) or the formula (Ib) is preferable.

(In Formula (Ia) and Formula (Ib), R ¹ represents a hydrogen atom or a methyl group. R ² represents a linear, branched or cyclic alkyl group having 1 to 8 carbon atoms. R ³ represents a methyl group, n represents an integer of 0 to 14. R ⁴ and R ⁵ each independently represents a hydrogen atom or a monovalent carbon atom that may contain a hetero atom having 1 to 8 carbon atoms. Represents a hydrogen group, or R ⁴ and R ⁵ may be bonded to each other to form a ring, in which case it represents a divalent hydrocarbon group which may contain a hetero atom having 1 to 8 carbon atoms. Further, R ⁴ and R ⁵ represents a direct bond between the carbon atoms in which carbon atoms and R ⁵ wherein R ⁴ is bonded to bond binds, i.e., the carbon atom to which carbon atoms and R ⁵ wherein R ⁴ is attached is bound .m but it may be formed a double bond, .Z representing the integer of 1 to 3 is a single bond or - represents a [CH _{2] k} -COO- group k represents an integer of 1 to 4. In this structural unit, the alicyclic ring bonded to the ester group is an acid-labile group, and this is easily caused by the action of an acid generated by exposure. By cleaving from the (meth) acrylate site, the resist film after exposure becomes alkali-soluble. As the structural unit (a), only one type of structural units represented by the formula (Ia) or the formula (Ib) may be used, or two or more types of these structural units may be used in combination. .

  Specific examples of the monomer for deriving the structural unit represented by the formula (Ia) include the following monomers.

  Specific examples of the monomer for deriving the structural unit represented by the formula (Ib) include the following monomers.

  Among these, when 2-ethyl-2-adamantyl (meth) acrylate, 2-isopropyl-2-adamantyl (meth) acrylate or 1- (2-methyl-2-adamantyloxycarbonyl) methyl methacrylate is used, It is more preferable because the obtained photoresist composition for immersion is excellent in sensitivity and heat resistance.

  Although these monomers can be easily produced by a known method, for example, 2-alkyl-2-adamantyl (meth) acrylate is usually 2-alkyl-2-adamantanol or a metal salt thereof and acrylic acid halide or methacrylic acid. It can be produced by reaction with an acid halide.

  Among the structural units constituting the resin, (a) the proportion of the structural unit having an acid labile group in the side chain is insensitive to the type of radiation used for patterning exposure, the type of acid labile group, and the acid. Although it varies depending on the type of the stable group and the like, it is not particularly limited, but may be in the range of 10 to 80 mol%, for example.

  As the structural unit (a) having a hydroxyl group in the side chain, a structural unit represented by the formula (II) is preferable. As the structural unit (a), only one type of structural unit represented by the formula (II) may be used, or two or more types of structural units may be used in combination.

(In Formula (II), R ¹ represents a hydrogen atom or a methyl group. R ⁶ and R ⁷ each independently represents a hydrogen atom, a methyl group or a hydroxyl group. R ⁸ represents a methyl group. N ′ represents And represents an integer of 0 to 12. Z represents a single bond or a — [CH ₂ ] _k —COO— group, and k represents an integer of 1 to 4.)
Specific examples of the monomer that leads to the structural unit represented by the formula (II) include the following monomers.

  Among these, (meth) acrylic acid 3-hydroxy-1-adamantyl, (meth) acrylic acid 3, 5-dihydroxy-1-adamantyl, methacrylic acid 1- (3-hydroxy-1-adamantyloxycarbonyl) methyl, 1- (3,5-dihydroxy-1-adamantyloxycarbonyl) methyl methacrylate is more preferred because it provides a photoresist composition for immersion that exhibits high resolution.

  These monomers can be easily produced by a known method. For example, monomers such as 3-hydroxy-1-adamantyl (meth) acrylate and 3,5-dihydroxy-1-adamantyl (meth) acrylate are commercially available. However, it can also be produced, for example, by reacting the corresponding hydroxyadamantane with (meth) acrylic acid or its halide.

  Among the structural units constituting the photoresist resin, (a) the proportion of the structural unit having a hydroxyl group in the side chain is the type of radiation for patterning exposure, the type of acid labile group, and the group unstable to acid. Although it varies depending on the type of the material and is not particularly limited, it may be, for example, in the range of 0 to 40 mol%. Preferably it is 5-35 mol%. Within the above range, an immersion photoresist composition showing higher resolution can be provided.

  The structural unit (c) having a lactone structure in the side chain is represented by any one of the formula (IIIa), the formula (IIIb), the formula (IIIc), the formula (IIId), the formula (IIIe), or the formula (IIIf). The structural unit is preferred.

(In Formulas (IIIa) to (IIIf), R ¹ represents a hydrogen atom or a methyl group. R ⁹ represents a methyl group. L represents an integer of 0 to 5. l ″ represents 0 to (2j + 2). J represents an integer of 0 to 3. R ¹⁰ and R ¹¹ represent a carboxyl group, a cyano group, or a hydrocarbon group having 1 to 4 carbon atoms, and l ′ represents an integer of 0 to 3. When l ′ is 2 or more, a plurality of R ¹⁰ and R ¹¹ may be the same as or different from each other, Z represents a single bond or a — [CH ₂ ] _k —COO— group, 4 represents an integer of 4.) As the structural unit (c), only one type of structural units represented by formulas (IIIa) to (IIIf) may be used, or two or more types of these structural units may be used. May be used in combination.

  Specific examples of the monomer for deriving the structural unit represented by the formula (IIIa) include the following monomers.

  Specific examples of the monomer that leads to the structural unit represented by the formula (IIIb) include the following monomers.

  Specific examples of the monomer for deriving the structural unit represented by formula (IIIc) include the following monomers.

  Specific examples of the monomer that leads to the structural unit represented by the formula (IIId) include the following monomers.

  Specific examples of the monomer that leads to the structural unit represented by the formula (IIIe) include the following monomers.

  Specific examples of the monomer that leads to the structural unit represented by the formula (IIIf) include the following monomers.

  Among these, (meth) acrylic acid hexahydro-2-oxo-3,5-methano-2H-cyclopenta [b] furan-6-yl, (meth) acrylic acid tetrahydro-2-oxo-3-furyl, 2- (5-Oxo-4-oxatricyclo [4.2.1.0 ↑ 3,7 ↓] nonan-2-yloxy) -2-oxoethyl methacrylate is preferred.

  These monomers can be easily produced by known methods. For example, monomers such as (meth) acryloyloxy-γ-butyrolactone are α- or β-bromo-γ-butyrolactone in which the lactone ring may be substituted with alkyl. Acrylic acid or methacrylic acid may be reacted, or α- or β-hydroxy-γ-butyrolactone whose lactone ring may be substituted with alkyl may be reacted with acrylic acid halide or methacrylic acid halide. Moreover, the monomer which gives the structural unit represented by the formula (IIIb) or the formula (IIIc) is specifically produced by, for example, the reaction of the following alicyclic lactone having a hydroxyl group with (meth) acrylic acids. (For example, refer to Japanese Patent Laid-Open No. 2000-26446.)

  The proportion of (u) the structural unit having a lactone structure in the side chain in the structural units constituting the photoresist resin is the type of radiation used for patterning exposure, the type of acid labile group, and the acid labile. Although it varies depending on the type of the group and is not particularly limited, for example, it may be in the range of 0 to 80 mol%. Preferably it is 10-60 mol%. Within the above range, the substrate adhesion of the immersion photoresist composition is improved.

  As the structural unit (d) having a fluorine-containing structure in the side chain, a structural unit represented by the formula (IV) is preferable.

(In formula (IV), R ¹ represents a hydrogen atom or a methyl group. AR represents a linear, branched or cyclic aliphatic or alicyclic hydrocarbon group having 1 to 30 carbon atoms, At least one of the hydrogen atoms contained in the hydrocarbon group is substituted with a fluorine atom, and the carbon atom contained in the hydrocarbon group may be substituted with an oxygen atom, a nitrogen atom or a sulfur atom, The hydrogen atom contained in the hydrocarbon group may be substituted with a hydroxyl group or an alkyl group having 1 to 6 carbon atoms.) As the structural unit (d), 1 of the structural units represented by the formula (IV) Only seeds may be used, or two or more of these structural units may be used in combination.

  Specific examples of the monomer for deriving the structural unit represented by the formula (IV) include the following monomers.

  Among these, (meth) acrylic acid 5- (3,3,3-trifluoro-2-hydroxy-2- [trifluoromethyl] propyl) bicyclo [2.2.1] hept-2-yl, (meth ) Acrylic acid 6- (3,3,3-trifluoro-2-hydroxy-2- [trifluoromethyl] propyl) bicyclo [2.2.1] hept-2-yl, (meth) acrylic acid 4,4 -Bis (trifluoromethyl) -3-oxatricyclo [4.2.1.0. ↑ 2,5 ↓] Nonyl is more preferred because it provides an immersion photoresist composition that exhibits high resolution.

  Of the structural units constituting the photoresist resin, the proportion of the structural units having (d) fluorine-containing structures in the side chain is insensitive to the type of radiation used for patterning exposure, the type of acid-labile groups, and the acid. Although it varies depending on the type of the stable group and the like and is not particularly limited, for example, it may be in the range of 0 to 70 mol%, and more preferably in the range of 10 to 60 mol%. Within the above range, water-derived defects are suppressed due to the water repellent effect.

  The resin can also contain structural units derived from 2-norbornene. A resin containing such a structural unit has a rugged structure because it has an alicyclic group directly in its main chain, and exhibits excellent dry etching resistance. In the polymerization, 2-norbornene is introduced into the main chain by radical polymerization using, for example, an aliphatic unsaturated dicarboxylic anhydride such as maleic anhydride or itaconic anhydride in addition to the corresponding 2-norbornene. obtain. Accordingly, the structural unit derived from 2-norbornene is formed by opening a double bond of the norbornene structure and can be represented by the formula (d). The structural unit derived from maleic anhydride and itaconic anhydride is maleic anhydride. A double bond of acid and itaconic anhydride is formed by opening and can be represented by formulas (e) and (f), respectively.

Here, R ²⁵ and R ²⁶ in formula (d) are each independently a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, a hydroxyl group, a carboxyl group, a cyano group, or —COOU (U is an alcohol residue). Or R ²⁵ and R ²⁶ represent a carboxylic acid anhydride residue represented by —C (═O) OC (═O) —.

  The —COOU is an ester of a carboxyl group, and examples of the alcohol residue corresponding to U include an optionally substituted alkyl group having about 1 to 8 carbon atoms, 2-oxooxolane— A 3- or -4-yl group etc. can be mentioned. Here, a hydroxyl group, an alicyclic hydrocarbon residue, or the like may be bonded as a substituent of the alkyl group.

Specific examples of R ²⁵ and / or R ²⁶ being an alkyl group include a methyl group, an ethyl group, and a propyl group. Specific examples of the alkyl group to which a hydroxyl group is bonded include a hydroxymethyl group, 2- Examples thereof include a hydroxyethyl group.

  Specific examples of the monomer that leads to the norbornene structure represented by the formula (d) include the following compounds.

2-norbornene,
2-hydroxy-5-norbornene,
5-norbornene-2-carboxylic acid,
Methyl 5-norbornene-2-carboxylate,
2-hydroxy-1-ethyl 5-norbornene-2-carboxylate,
5-norbornene-2-methanol,
5-norbornene-2,3-dicarboxylic anhydride.

  In addition, about U of —COOU in the formula (d), a norbornene structure is used as long as it is an acid-labile group such as an alicyclic ester in which the carbon atom bonded to the oxygen side of the carboxyl group is a quaternary carbon atom. However, it corresponds to the structural units (a) and (a) ′ having an acid labile group in the side chain. Examples of the monomer containing a norbornene structure and an acid labile group include, for example, 5-norbornene-2-carboxylic acid-t-butyl, 5-norbornene-2-carboxylic acid 1-cyclohexyl-1-methylethyl, and 5-norbornene. 2-carboxylate 1-methylcyclohexyl, 5-norbornene-2-carboxylic acid 2-methyl-2-adamantyl, 5-norbornene-2-carboxylic acid 2-ethyl-2-adamantyl, 5-norbornene-2-carboxylic acid 1- (4-methylcyclohexyl) -1-methylethyl, 5-norbornene-2-carboxylic acid 1- (4-hydroxycyclohexyl) -1-methylethyl, 5-norbornene-2-carboxylic acid 1-methyl-1- (4-Oxocyclohexyl) ethyl, 5-norbornene-2-carboxylic acid 1- (1-adama) Chill) -1-methylethyl and the like.

  The molecular weight of the photoresist resin that can be used in the present invention is not particularly limited, but is usually about 1,000 to 500,000 in weight average molecular weight, and preferably 4,000 to 50,000.

  The method for producing the resin of the present invention is not particularly limited, and various polymerization methods can be used. Among these, the radical polymerization method is preferable. Specifically describing this radical polymerization method, first, each monomer to be polymerized and a radical polymerization initiator are sequentially added to and dissolved in an organic solvent, and then the reaction solution is kept at a predetermined reaction temperature. The desired copolymer is obtained.

  Although the organic solvent used by the said polymerization method is not specifically limited, The solvent which can melt | dissolve all of a monomer, a polymerization initiator, and the copolymer obtained is preferable. Examples of such an organic solvent include hydrocarbons such as toluene, 1,4-dioxane, tetrahydrofuran, methyl isobutyl ketone, isopropyl alcohol, γ-butyrolactone, propylene glycol monomethyl ether acetate, and ethyl lactate. These solvents may be used alone or in combination of two or more.

  The polymerization initiator is not particularly limited, and a known compound can be used. Specifically, for example, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane-1-carbonitrile), 2 , 2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl-2,2′-azobis (2-methylpropionate) ), 2,2′-azobis (2-hydroxymethylpropionitrile) and the like; lauryl peroxide, tert-butyl hydroperoxide, benzoyl peroxide, tert-butyl peroxybenzoate, cumene hydroperoxide, Diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, tert-butyl Organic peroxides such as peroxyneodecanoate, tert-butyl peroxypivalate, (3,5,5-trimethylhexanoyl) peroxide; inorganic peroxides such as potassium persulfate, ammonium persulfate, and hydrogen peroxide Etc.

  Of these, azo compounds are preferred, and 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile). ), 1,1′-azobis (cyclohexane-1-carbonitrile) and dimethyl-2,2′-azobis (2-methylpropionate), more preferably 2,2′-azobisisobutyronitrile, 2 2,2′-azobis (2,4-dimethylvaleronitrile) is more preferred. When two kinds of polymerization initiators are used in combination, 2,2′-azobis (2,4-dimethylvaleronitrile) and 2,2′-azobisisobutyronitrile are combined, 2,2′-azobis ( 2,2-dimethylvaleronitrile) and 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile) and 1,1′-azobis ( A combination with cyclohexane-1-carbonitrile), and a combination of 2,2′-azobis (2,4-dimethylvaleronitrile) and dimethyl-2,2′-azobis (2-methylpropionate), The molar ratio is preferably in the range of 1: 1 to 1:10.

  The reaction temperature for radical polymerization for producing the resin of the present invention is usually in the range of 0 to 150 ° C, preferably in the range of 40 to 100 ° C. The amount of the organic solvent used is preferably 1 to 5 times by weight based on the total amount of charged monomers, and the amount of the polymerization initiator used is preferably 1 to 20 mol% with respect to the total amount of charged monomers.

  The photoresist composition of the present invention contains an acid generator that generates an acid upon exposure, in addition to the resins detailed above.

  The acid generator decomposes the substance to generate an acid by applying radiation such as light or electron beam to the substance itself or to a positive photoresist composition containing the substance. The acid generated from the acid generator acts on the resin to cleave the alicyclic ring in the structural unit (a) represented by the formula (Ia) or (Ib) from the (meth) acrylate site. .

  Examples of the acid generator include onium salts, organic halogen compounds, sulfone compounds, and sulfonate compounds, and onium salts are preferable. As an acid generator, the acid generator described in Unexamined-Japanese-Patent No. 2003-5374 is mentioned, for example.

  Examples of the acid generator used in the present invention include compounds represented by the following formula (V).

In the formula (V), R ¹² represents a linear or branched hydrocarbon group having 1 to 6 carbon atoms or a cyclic hydrocarbon group having 3 to 30 carbon atoms. However, the carbon atom contained in the hydrocarbon group may be substituted with a carbonyl group or an oxygen atom, and the hydrocarbon group is an alkoxy group having 1 to 6 carbon atoms or a perfluoroalkyl group having 1 to 4 carbon atoms. In addition, one or more of a hydroxyalkyl group having 1 to 6 carbon atoms, a hydroxyl group, a cyano group, a carbonyl group, and an ester group may be included as a substituent. The cyclic hydrocarbon group is one of an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a perfluoroalkyl group having 1 to 4 carbon atoms, a cyano group, a carbonyl group, a hydroxyl group, and an ester group. One or more may be included as a substituent. A ⁺ represents an organic counter ion. Y ¹ and Y ² each independently represent a fluorine atom or a C 1-6 perfluoroalkyl group. )
Specific examples of the anion moiety of the compound represented by the formula (V) include the following anions.

  Preferable acid generators used in the present invention include compounds represented by the following formula (VI) or formula (VII).

In formula (VI) and formula (VII), ring X represents a monocyclic or polycyclic hydrocarbon group having 3 to 30 carbon atoms. A ⁺ represents an organic counter ion. Y ¹ and Y ² each independently represent a fluorine atom or a C 1-6 perfluoroalkyl group. The ring X is substituted with an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a perfluoroalkyl group having 1 to 4 carbon atoms, a hydroxyalkyl group having 1 to 6 carbon atoms, a hydroxyl group, or a cyano group. May be included. Z ′ represents a single bond or an alkylene group having 1 to 4 carbon atoms.

  Examples of the ring X include a cycloalkyl skeleton having 4 to 8 carbon atoms, an adamantyl skeleton, and a norbornane skeleton. Any of the skeletons are substituted with an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a perfluoroalkyl group having 1 to 4 carbon atoms, a hydroxyalkyl group having 1 to 6 carbon atoms, a hydroxyl group, or a cyano group. May be included.

  The following anions are mentioned as a specific example of the anion part of the acid generator represented by Formula (VI) and Formula (VII).

Examples of the acid generator used in the present invention include compounds represented by the following formula (VIII).
A ⁺ -O ₃ S-R ¹³ (VIII)
In the formula (VIII), R ¹³ represents a linear or branched perfluoroalkyl group having 1 to 6 carbon atoms, and A ⁺ represents an organic counter ion.

Specific examples of the anion moiety of formula (VIII) include the following ions.
Trifluoromethanesulfonate,
Pentafluoroethanesulfonate,
Heptafluoropropanesulfonate,
Perfluorobutane sulfonate.

In the formula (V), (VI), (VII) or (VIII), A ⁺ represents an organic counter ion, specifically, the following formula (IXz), formula (IXb), formula (IXc) Or at least 1 sort (s) of cation chosen from the group which consists of a cation represented by a formula (IXd) is mentioned.

  Here, the formula (IXz) is the following formula.

In formula (IXz), P ^{a to} P ^c each independently represents a linear or branched alkyl group having 1 to 30 carbon atoms or a cyclic hydrocarbon group having 3 to 30 carbon atoms. The alkyl group may contain one or more of a hydroxyl group, an alkoxy group having 1 to 12 carbon atoms, and a cyclic hydrocarbon group having 3 to 12 carbon atoms as a substituent, and the cyclic hydrocarbon group is In addition, one or more of a hydroxyl group, an alkyl group having 1 to 12 carbon atoms, and an alkoxy group having 1 to 12 carbon atoms may be included as a substituent. The alkyl group and the alkoxy group may be linear or branched.

  Among the cations represented by the formula (IXz), the cation represented by the formula (IXa) is preferable.

In Formula (IXa), P ^{1 to} P ³ each independently represent a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms, and the alkyl group and the alkoxy group are They may be linear or branched. )
Specific examples of the alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl. Examples of the alkoxy group include methoxy group, ethoxy group, propoxy group, butoxy group, hexyloxy group, octyloxy group, 2-ethylhexyloxy group and the like.

  Formula (IXb) is the following formula containing an iodine cation.

In Formula (IXb), P ⁴ and P ⁵ each independently represent a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms, and the alkyl group and the alkoxy group are Represents the same meaning as the alkyl group and alkoxy group of formula (IXa).

  Formula (IXc) is the following formula.

In formula (IXc), P ⁶ and P ⁷ each independently represent an alkyl group having 1 to 12 carbon atoms or a cycloalkyl group having 3 to 12 carbon atoms. The alkyl group may be linear or branched. Specific examples of the alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl. Groups and the like. Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclodecyl group. P ⁶ and P ⁷ may be bonded to form a C 3-12 divalent hydrocarbon group such as an alkylene group. P ⁸ represents a hydrogen atom, and P ⁹ represents an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or an optionally substituted aromatic ring group (for example, phenyl group, benzyl group). Group) or P ⁸ and P ⁹ are bonded to each other to represent a C 3-12 divalent hydrocarbon group such as an alkylene group. The alkyl group representing P ⁹ may be linear or branched. Specific examples of the alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl. Groups and the like. Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclodecyl group. Any carbon atom contained in the divalent hydrocarbon group may be substituted with a carbonyl group, an oxygen atom, or a sulfur atom.

  Formula (IXd) is the following formula.

In formula (IXd), P ^{10 to} P ²¹ each independently represents a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. The alkyl group and the alkoxy group have the same meaning as the alkyl group and alkoxy group of the formula (IXa).

  B represents a sulfur atom or an oxygen atom. m represents 0 or 1.

Specific examples of the cation A ⁺ represented by the formula (IXz) include the following cations.

Specific examples of the cation A ⁺ represented by the formula (IXb) include the following cations.

Specific examples of the cation A ⁺ represented by the formula (IXc) include the following cations.

Specific examples of the cation A ⁺ represented by the formula (IXd) include the following cations.

A ⁺ is preferably a cation represented by the formula (IXe).

In formula (IXe), P ^{22 to} P ²⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and the alkyl group may be linear or branched.

  In the positive photoresist composition of the present invention, the acid generator may be used alone or in combination of two or more.

  Among the acid generators used in the present invention, the acid generator represented by the above formula (VI) or (VII) is preferable, and further represented by the following formula (Xa), (Xb) or (Xc). The acid generator is more preferred because it provides a photoresist composition that exhibits excellent resolution and pattern shape.

In formulas (Xa) to (Xc), P ^{25 to} P ²⁷ each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. P ²⁸ and P ²⁹ each independently represent an alkyl group having 1 to 12 carbon atoms or a cycloalkyl group having 3 to 12 carbon atoms, and the alkyl group may be linear or branched. Alternatively, by bonding and P ²⁸ and P ^29, it may form a divalent hydrocarbon group having 3 to 12 carbon atoms such as an alkylene group. P ³⁰ represents a hydrogen atom, and P ³¹ represents an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or an optionally substituted aromatic ring group, or P ³⁰ P ³¹ is bonded to represent a C 3-12 divalent hydrocarbon group. Here, the carbon atom contained in the divalent hydrocarbon group may be substituted with a carbonyl group, an oxygen atom, or a sulfur atom. Y ¹¹ , Y ¹² , Y ²¹ , Y ²² , Y ³¹ , or Y ³² each independently represents a fluorine atom or a C 1-6 perfluoroalkyl group.

  The acid generator represented by the formula (VI) or the formula (VII) can be easily synthesized by a known method (for example, see JP-A-2007-249192).

  The photoresist composition of the present invention preferably contains a basic compound together with the resin and acid generator described above. The basic compound acts as a quencher, and this compounding can improve performance deterioration due to acid deactivation accompanying holding after exposure. As the basic compound, a basic nitrogen-containing organic compound is preferable, and an amine or an ammonium salt is more preferable.

  Specific examples of the basic compound used for the quencher include compounds represented by the following formulas.

In the formula, T ¹ , T ² and T ⁷ each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group or an aryl group. The hydrogen atom of the alkyl group, the hydrogen atom of the cycloalkyl group, or the hydrogen atom of the aryl group may be each independently substituted with a hydroxyl group, an amino group, or an alkoxy group having 1 to 6 carbon atoms. The hydrogen atom of the amino group may be substituted with an alkyl group having 1 to 4 carbon atoms. The alkyl group preferably has about 1 to 6 carbon atoms, the cycloalkyl group preferably has about 5 to 10 carbon atoms, and the aryl group preferably has about 6 to 10 carbon atoms.

T ³ , T ⁴ and T ⁵ each independently represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group or an alkoxy group. The hydrogen atom of the alkyl group, the hydrogen atom of the cycloalkyl group, the hydrogen atom of the aryl group, or the hydrogen atom of the alkoxy group is each independently substituted with a hydroxyl group, an amino group, or an alkoxy group having 1 to 6 carbon atoms. May be. The hydrogen atom of the amino group may be substituted with an alkyl group having 1 to 4 carbon atoms. In addition, the alkyl group preferably has about 1 to 6 carbon atoms, the cycloalkyl group preferably has about 5 to 10 carbon atoms, the aryl group preferably has about 6 to 10 carbon atoms, and the alkoxy group has carbon atoms. A number of about 1 to 6 is preferable.

T ⁶ represents an alkyl group or a cycloalkyl group. The hydrogen atom of the alkyl group or the hydrogen atom of the cycloalkyl group may be each independently substituted with a hydroxyl group, an amino group, or an alkoxy group having 1 to 6 carbon atoms. The hydrogen atom of the amino group may be substituted with an alkyl group having 1 to 4 carbon atoms. The alkyl group preferably has about 1 to 6 carbon atoms, and the cycloalkyl group preferably has about 5 to 10 carbon atoms.

  A represents an alkylene group, a carbonyl group, an imino group, a sulfide group or a disulfide group. The alkylene preferably has about 2 to 6 carbon atoms.

In addition, any of T ^{1 to} T ⁷ that can take both a linear structure and a branched structure may be used.

  Specific examples of the basic compound include hexylamine, heptylamine, octylamine, nonylamine, decylamine, aniline, 2-, 3- or 4-methylaniline, 4-nitroaniline, 1- or 2-naphthylamine, and ethylenediamine. , Tetramethylenediamine, hexamethylenediamine, 4,4′-diamino-1,2-diphenylethane, 4,4′-diamino-3,3′-dimethyldiphenylmethane, 4,4′-diamino-3,3′- Diethyldiphenylmethane, dibutylamine, dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, N-methylaniline, piperidine, diphenylamine, triethylamine, trimethylamine, tripropylamine, tributylamine , Tripentylamine, trihexylamine, triheptylamine, trioctylamine, trinonylamine, tridecylamine, methyldibutylamine, methyldipentylamine, methyldihexylamine, methyldicyclohexylamine, methyldiheptylamine, methyldioctylamine Methyldinonylamine, methyldidecylamine, ethyldibutylamine, ethyldipentylamine, ethyldihexylamine, ethyldiheptylamine, ethyldioctylamine, ethyldinonylamine, ethyldidecylamine, dicyclohexylmethylamine, tris [2- (2-methoxyethoxy) ethyl] amine, triisopropanolamine, N, N-dimethylaniline, 2,6-diisopropylaniline, imidazole, pyridine 4-methylpyridine, 4-methylimidazole, bipyridine, 2,2'-dipyridylamine, di-2-pyridyl ketone, 1,2-di (2-pyridyl) ethane, 1,2-di (4-pyridyl) ethane 1,3-di (4-pyridyl) propane, 1,2-bis (2-pyridyl) ethylene, 1,2-bis (4-pyridyl) ethylene, 1,2-bis (4-pyridyloxy) ethane, 4,4'-dipyridyl sulfide, 4,4'-dipyridyl disulfide, 1,2-bis (4-pyridyl) ethylene, 2,2'-dipicolylamine, 3,3'-dipicolylamine, tetramethylammonium hydroxy , Tetraisopropylammonium hydroxide, tetrabutylammonium hydroxide, tetra-n-hexylammonium hydroxide, tetra-n -Octylammonium hydroxide, phenyltrimethylammonium hydroxide, 3- (trifluoromethyl) phenyltrimethylammonium hydroxide and choline can be mentioned. In addition, a hindered amine compound having a piperidine skeleton as disclosed in JP-A-11-52575 can also be used.

  As the basic compound used in the present invention, a compound represented by the formula (XII) is preferable from the viewpoint of improving the resolution. Specific examples of the compound represented by the formula (XII) include tetramethylammonium hydroxide, tetrabutylammonium hydroxide, tetrahexylammonium hydroxide, tetraoctylammonium hydroxide, phenyltrimethylammonium hydroxide, 3-trifluoro And methyl-phenyltrimethylammonium hydroxide.

  The photoresist composition of the present invention contains 75-96.9% by weight of the photoresist resin, 0.1-20% by weight of the acid generator, and 3-5% by weight of the polymer of the present invention. (However, the total of these three components is 100% by weight). Within this blending ratio range, it is easy to obtain a resist film having a large water receding angle. Moreover, when mix | blending the basic compound which is a quencher, what is necessary is just to mix | blend in the range of about 0.01 to 1 weight% normally on the basis of the total amount of solid content of the said composition.

  The photoresist composition of the present invention can further contain a small amount of various additives such as a sensitizer, a dissolution inhibitor, other resins, a surfactant, a stabilizer, and a dye, if necessary.

  The photoresist composition of the present invention is usually applied to a substrate such as a silicon wafer in a state where the above-described components are dissolved in a solvent according to a method that is usually used industrially, such as spin coating. The solvent used here may be any solvent that dissolves each component, has an appropriate drying rate, and gives a uniform and smooth coating film after the solvent evaporates, and a solvent generally used in this field is used. Yes. For example, ethyl etherosolve acetate, methyl cellosolve acetate, glycol ether esters such as propylene glycol monomethyl ether acetate, glycol ethers such as propylene glycol monomethyl ether, esters such as ethyl lactate, butyl acetate, amyl acetate and ethyl pyruvate, acetone And ketones such as methyl isobutyl ketone, 2-heptanone (methyl amyl ketone) and cyclohexanone, and cyclic esters such as γ-butyrolactone. These solvents can be used alone or in combination of two or more.

  The resist film coated and dried on the substrate is subjected to an exposure process for patterning, followed by a heat treatment for promoting a deprotecting group reaction, and then developed with an alkali developer. The alkaline developer used here may be various alkaline aqueous solutions used in this field, and examples thereof include aqueous solutions of tetramethylammonium hydroxide and (2-hydroxyethyl) trimethylammonium hydroxide (commonly called choline).

  The photoresist composition containing the polymer of the present invention can provide a resist film having a large water receding angle. Therefore, in a lithography process, particularly a lithography process of an immersion exposure method, a resist with less generation of defects. It becomes possible to give a film.

  EXAMPLES Next, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited at all by these Examples. In the examples, “%” and “part” representing the content or amount used are based on weight unless otherwise specified. The average molecular weight is a value determined by gel permeation chromatography. Measurement conditions are as follows.

Column: TSKgel Multipore H _XL -M x 3 + guardcolumn (manufactured by Tosoh Corporation)
Eluent: Tetrahydrofuran Flow rate: 1.0 mL / min
Detector: RI detector Column temperature: 40 ° C
Injection volume: 100 μl
Molecular weight standard: Standard polystyrene (manufactured by Tosoh Corporation)
Synthesis example 1
[Synthesis of photoresist resin: A1]
15.00 g of monomer A, 4.89 g of monomer B, 11.12 g of monomer C, and 8.81 g of monomer D (molar ratio 35: 12: 23: 30), 1.5 times the total amount of monomers 1,4-dioxane was added to make a solution. Thereto, 2,2′-azobisisobutyronitrile and 2,2′-azobis (2,4-dimethylvaleronitrile) were added as initiators in an amount of 1 mol% and 3 mol%, respectively, with respect to the total monomer amount, and 77 ° C. For about 5 hours. Thereafter, the reaction solution was purified by pouring it into a large amount of a mixed solvent of methanol and water and precipitating three times to obtain a copolymer having a weight average molecular weight of about 8100 in a yield of 78%. This copolymer has each structural unit of the following formula, and this is designated as resin A1.

Synthesis example 2
[Synthesis of photoresist resin: A2]
5.20 parts of monomer E, 2.62 parts of monomer B and 10.37 parts of monomer C were charged (molar ratio 50:25:25), and 1,4-dioxane was 2.6 times by weight of the total amount of monomers. In addition, a solution was obtained. 2,2′-azobisisobutyronitrile as an initiator was added thereto in an amount of 3 mol% with respect to the total amount of monomers, and heated at 87 ° C. for about 5 hours. Thereafter, the reaction solution was purified by pouring it into a mixed solvent of a large amount of methanol and water for three times to obtain a copolymer having a weight average molecular weight of about 10600 in a yield of 81%. This copolymer has each structural unit of the following formula, and this is designated as resin A2.

Polymers B1 to B3:
DUVCOR A5100 series (addition polymer of monomer P) manufactured by Sumitomo Bakelite Co., Ltd. was used.

Polymer B1: DUVCOR A5100 Lot. 2057 (Mw 9590 Mw / Mn 1.94)
Polymer B2: DUVCOR A5100 Lot. 2056 (Mw 5580 Mw / Mn 1.45)
Polymer B3: DUVCOR A5100 Lot. 2055 (Mw 8210 Mw / Mn 1.64)
Examples 1-7 and Comparative Examples 1-3
Each component shown in Table 1 and below was mixed and dissolved at the stated ratios, and further filtered through a fluororesin filter having a pore size of 0.2 μm to prepare a photoresist composition.
<Acid generator>
Acid generator: C1

Acid generator: C2

<Quencher>
Quencher Q1: 2,6-diisopropylaniline 0.03 part <solvent>
Propylene glycol monomethyl ether acetate 140 parts Propylene glycol monomethyl ether 20 parts 2-heptanone 35 parts γ-butyrolactone 3 parts Next, the receding angle of the unexposed film was measured. The results are shown in Table 1.

  The test procedure and results of the receding angle are shown below.

  The quencher and solvent are mixed in the above parts, and the photoresist resin, polymer and acid generator are mixed and dissolved in the parts described in Table 1 below, and further filtered through a fluororesin filter having a pore diameter of 0.2 μm. A photoresist composition was prepared.

  On the silicon wafer, the said composition was spin-coated so that the film thickness after drying might be set to 0.15 micrometer. After application of the above composition, it was pre-baked on a direct hot plate to 100 ° C. for 60 seconds. With respect to each wafer on which the resist film was thus formed, the receding angle was measured using Drop Master-700 manufactured by Kyowa Interface Science. The receding angle was measured in a graded slope mode using 50 microliters of water by the slope method.

  The photoresist compositions of Examples 1 to 7 were spin-coated on a silicon wafer so that the film thickness after drying was 0.15 μm. After applying the photoresist composition, it was pre-baked at 100 ° C. for 60 seconds on a direct hot plate. The film thickness of the resist film was measured using a film thickness meter (VM-3100, manufactured by Dainippon Screen Mfg. Co., Ltd.).

  Each wafer on which the resist film was formed was post-exposure baked on a hot plate at 105 ° C. for 60 seconds, and further paddle developed for 60 seconds with a 2.38 wt% tetramethylammonium hydroxide aqueous solution. The film thickness of the remaining resist film was measured in the same manner.

  When the remaining film ratio (%) was calculated according to the following formula, it was found that the remaining film ratio was around 99% and could be used as a resist film.

  In all of the examples, the receding angle was high and good results were obtained.

  The photoresist composition containing the polymer of the present invention can provide a resist film having a large water receding angle.

Claims (5)

It contains a structural unit derived from a monomer having at least two trifluoromethyl groups, a monovalent unsaturated cyclic group represented by the formula (1), and a hydroxyl group in one molecule. To polymer.

(In the formula, A represents a single bond, a methylene group, an isopropylidene group or an oxygen atom.) The polymer according to claim 1, wherein the monomer is a compound represented by the formula (2).

(In the formula, A represents a single bond, a methylene group, an isopropylidene group or an oxygen atom. R represents an alkylene group having 1 to 12 carbon atoms. The methylene group in the alkylene group is substituted with an oxygen atom. The hydrogen atom in the alkylene group may be substituted with a fluorine atom.) The polymer according to claim 1, wherein the monomer is a compound represented by the formula (3).
  A photoresist composition comprising a photoresist resin that changes to alkali solubility by the action of an acid, an acid generator, and the polymer according to claim 1.   The proportions of the photoresist resin, the acid generator, and the polymer are 75 to 96.9% by weight, 0.1 to 20% by weight, and 3 to 5% by weight, respectively (however, these 5. The photoresist composition according to claim 4, wherein the total of the three components is 100% by weight.