JP5540818B2 - Radiation-sensitive resin composition and polymer - Google Patents

Description

  The present invention relates to a chemically amplified radiation-sensitive resin composition useful for fine processing in a manufacturing process of a semiconductor such as an integrated circuit, a manufacturing process of a circuit board such as a liquid crystal or a thermal head, and other photolithography processes, and a composition thereof. It is related with the polymer used for etc.

  In recent years, in the field of microfabrication represented by the manufacture of integrated circuits and the like, in order to obtain a higher degree of integration, the processing size in the lithography process has been miniaturized, and a technique for stably performing such microfabrication is required. It has been. Therefore, it is necessary to form a fine pattern with high precision for the resist used, and lithography using radiation with shorter wavelengths is being studied.

  As short-wavelength radiation, far ultraviolet rays typified by KrF excimer laser (wavelength 248 nm) and ArF excimer laser (wavelength 193 nm), charged particle beams typified by electron beams, and the like are used. Various resist compositions that can be used have been studied. Among such resist compositions, acid is generated in the exposed area by irradiation with radiation (hereinafter also referred to as “exposure”), and the dissolution rate of the exposed area and the unexposed area in the developer by the catalytic action of this acid. There is known a radiation-sensitive resin composition that causes a difference between the two and forms a resist pattern on a substrate. The ArF excimer laser is also used in immersion exposure that enables further fine processing by using immersion.

  As these techniques, for example, in Japanese Patent Application Laid-Open No. 2002-23371, a polymer having a structural unit having an oxazolidinone skeleton is used as a constituent material as a lithographic material capable of fine processing at a shorter wavelength using an ArF excimer laser as a light source. A radiation sensitive resin composition is disclosed.

  However, even with such a radiation-sensitive resin composition, in recent years when further device miniaturization is progressing, resist characteristics such as sensitivity, resolution, and exposure margin cannot be sufficiently satisfied. There is a demand for a radiation-sensitive resin composition that is capable of forming a chemically amplified resist that is more excellent in resist characteristics.

JP 2002-23371 A

  The present invention has been made in view of such inconveniences, and an object of the present invention is to provide a novel radiation-sensitive resin composition excellent in sensitivity, resolution and exposure margin, and a polymer used for the composition.

（式（Ｉ）中、Ｒ^１は、水素原子又はメチル基である。Ｒ^２は、炭素数１〜２０の炭化水素基である。） The invention made to solve the above problems is
[A] a polymer having a structural unit represented by the following formula (I) (hereinafter also referred to as “structural unit (1)”), and [B] a radiation-sensitive resin containing a radiation-sensitive acid generator. It is a composition.

(In Formula (I), R ¹ is a hydrogen atom or a methyl group. R ² is a hydrocarbon group having 1 to 20 carbon atoms.)

The radiation-sensitive resin composition contains a polymer [A] having the structural unit (1) and [B] a radiation-sensitive acid generator (hereinafter also referred to as “acid generator [B]”). To do. Since the polymer [A] has an oxazolinone group, the polymer [A] has an affinity for an alkali developer, and further has a linking group represented by R ^2. Affinity for is improved. In the present specification, the “structural unit” means one unit included in the polymer structure, and may be present repeatedly.

In the above formula (I), ^{R 2} is preferably a alkanediyl group having 1 to 4 carbon atoms. By setting R ² to a chain length in a more preferable range, both the flexibility of the side chain and the rigidity of the resin can be achieved, and the sensitivity, resolution, and exposure margin can be further increased.

（式（ＩＩ）中、Ｒ^３は、水素原子又はメチル基である。Ｒ^４は、炭素数１〜４のアルキル基又は炭素数４〜２０の１価の脂環式炭化水素基である。Ｒ^５及びＲ^６は、それぞれ独立して、炭素数１〜４のアルキル基又は炭素数４〜２０の１価の脂環式炭化水素基であるか、又はＲ^５及びＲ^６が互いに結合して、それらが結合している炭素原子と共に炭素数４〜２０の２価の脂環式炭化水素基を形成する。） The polymer [A] preferably further has a structural unit represented by the following formula (II) (hereinafter also referred to as “structural unit (2)”).

(In the formula (II), ^{R 3} is, .R ⁴ is a hydrogen atom or a methyl group, a monovalent alicyclic hydrocarbon group having an alkyl group or 4 to 20 carbon atoms having 1 to 4 carbon atoms. R ⁵ and R ⁶ are each independently an alkyl group having 1 to 4 carbon atoms or a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms, or R ⁵ and R ⁶ are bonded to each other. And a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms together with the carbon atom to which they are bonded.)

  When the polymer [A] further has the structural unit (2), the pattern forming ability of the radiation-sensitive resin composition containing the polymer [A] is improved, and the resolution as a resist is improved.

  The polymer [A] preferably further includes at least one selected from a structural unit containing a lactone structure and a structural unit containing a cyclic carbonate structure (hereinafter also referred to as “structural unit (3)”). When the polymer [A] further has the structural unit (3), the radiation-sensitive resin composition can exhibit resist characteristics in which sensitivity, resolution, and exposure allowance are more highly balanced. As a result, a resist having an excellent process margin can be obtained. Here, “excellent process margin” means that usable conditions for exposure and development (for example, conditions such as time and temperature) for pattern formation in the process are wide. In addition, a synergistic effect of improving developability as a resist, low defect property, low post exposure bake (hereinafter also referred to as “PEB”) temperature dependency, and the like is exhibited.

（式（Ｉ）中、Ｒ^１は、水素原子又はメチル基である。Ｒ^２は、炭素数１〜２０の炭化水素基である。） The polymer of the present invention has a structural unit represented by the following formula (I).

(In Formula (I), R ¹ is a hydrogen atom or a methyl group. R ² is a hydrocarbon group having 1 to 20 carbon atoms.)

Since the polymer has an oxazolinone group, it has an affinity for an alkaline developer, and further has a linking group represented by R ² , so that the polymer can easily come into contact with the alkali developer, and further has an affinity for an alkali developer. For example, it is considered that it can be suitably used for a radiation-sensitive resin composition used in lithography technology.

  As described above, the radiation-sensitive resin composition of the present invention contains a polymer having a structural unit having a specific structure, and thus has superior sensitivity, resolution, and exposure compared to conventional radiation-sensitive resin compositions. You can demonstrate your spare time. Therefore, as a chemically amplified radiation-sensitive resin composition sensitive to actinic radiation of short wavelength, it is possible to manufacture products with an excellent process margin at the time of microfabrication, and further integration is expected to progress further in the future. It can be suitably used in the field of circuit elements and the like.

  The radiation sensitive resin composition of this invention contains the polymer which has [A] structural unit (1), and an acid generator [B], and can contain another arbitrary component as needed. Hereinafter, the present invention will be described in detail. The “radiation” of the “radiation-sensitive resin composition” and “radiation-sensitive acid generator” in the present specification is a concept including visible light, ultraviolet light, far ultraviolet light, X-rays, charged particle beams, and the like. is there.

(Polymer [A])
The polymer [A] is usually a polymer that is insoluble or hardly soluble in alkali, but becomes alkali-soluble by an acid generated from the acid generator [B] during exposure. Further, the polymer [A] is characterized by having an oxazolinone group exhibiting an affinity for an alkali developer. The term “alkali-insoluble or alkali-insoluble” as used herein refers to a resist film under the alkali development conditions employed when a resist pattern is formed from a resist film formed from the radiation-sensitive resin composition. When a film using only the polymer [A] is developed instead of 50%, it means a property that 50% or more of the initial film thickness of the film remains after development.

Further, as illustrated above formula (I), oxazolidinone group via R ² and ester bond with an appropriate chain length, bonded to the carbon atoms constituting the main chain skeleton of the resin. By having this specific structure, it becomes easy to contact with an alkaline developer, and the affinity for the alkaline developer is further improved. Therefore, for example, the polymer [A] can be suitably used for a radiation-sensitive resin composition used in lithography technology.

R ^{1 in the} above formula (I) is a hydrogen atom or a methyl group, and R ² is a hydrocarbon group having 1 to 20 carbon atoms. Examples of the hydrocarbon group having 1 to 20 carbon atoms represented by R ² include:
Methylene group, ethylene group, n-propylene group, i-propylene group, n-butylene group, n-pentylene group, n-hexylene group, n-heptylene group, n-octylene group, n-nonylene group, n-decylene group A divalent linear or branched hydrocarbon group having 1 to 20 carbon atoms, such as
Bivalent alicyclic ring having 3 to 20 carbon atoms such as cyclobutanediyl group, cyclopentanediyl group, cyclohexanediyl group, cyclooctanediyl group, norbornanediyl group, tricyclodecanediyl group, tetracyclododecanediyl group, adamantanediyl group A hydrocarbon group of formula;
Arylene groups having 6 to 20 carbon atoms such as a phenylene group and a naphthylene group;
Examples thereof include an arylene alkylene group having 7 to 20 carbon atoms such as a benzylene group, a phenyleneethylene group, a phenylenepropylene group, a naphthylenemethylene group, and a naphthyleneethylene group.

Of these, R ² is preferably an alkanediyl group having 1 to 4 carbon atoms, more preferably an ethylene group, a propylene group and a butylene group, and particularly preferably an ethylene group. By setting R ² to a chain length in a more preferable range, both the flexibility of the side chain and the rigidity of the resin can be achieved, and the sensitivity, resolution, and exposure margin can be further increased.

The content of the structural unit (1) is preferably from 1 mol% to 60 mol%, more preferably from 1 mol% to 50 mol%, particularly preferably from 5 mol% to 40 mol%, based on all structural units constituting the polymer [A]. . When the content of the structural unit (1) is in the above range, the radiation-sensitive resin composition can exhibit resist characteristics in which sensitivity, resolution, and exposure margin are highly balanced. If it is less than 1mol%, -R ² - Effect of oxazolinone groups may not be sufficiently exhibited. If it exceeds 60 mol%, the resolution performance as a resist may be deteriorated.

The polymer [A] preferably further has the structural unit (2). The structural unit (2) is a unit having a group in which —CR ⁴ R ⁵ R ⁶ is dissociated to form a (meth) acrylic acid structure in the presence of an acid. Therefore, a polymer having the structural unit (2) [ A] becomes alkali-soluble from alkali-insoluble or alkali-insoluble by an acid generated from the acid generator [B].

  When the polymer [A] further has the structural unit (2), the pattern forming ability of the radiation-sensitive resin composition containing the polymer [A] is improved, and the resolution as a resist is improved.

In said formula (II), R < ³ > is a hydrogen atom or a methyl group. R ⁴ is an alkyl group having 1 to 4 carbon atoms or a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms. R ⁵ and R ⁶ are each independently an alkyl group having 1 to 4 carbon atoms or a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms, or R ⁵ and R ⁶ are bonded to each other. Thus, a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms is formed together with the carbon atom to which they are bonded.

The alkyl group having 1 to 4 carbon atoms represented by ^{R 4} in above-mentioned formula (II), for example, a methyl group, an ethyl group, n- propyl group, i- propyl and n- butyl. Examples of the monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms represented by R ⁴ include a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a norbornyl group, and a tricyclodecyl group. , Tetracyclododecyl group, adamantyl group and the like.

Examples of the alkyl group having 1 to 4 carbon atoms and the monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms represented by R ⁵ and R ⁶ in the above formula (II) include R ^{4 in the} above formula (II). The definition of can be applied. Examples of the divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms formed together with the carbon atom to which R ⁵ and R ^{6 in} the formula (II) are bonded to each other include, for example, Examples thereof include a cyclobutanediyl group, a cyclopentanediyl group, a cyclohexanediyl group, a cyclooctanediyl group, a norbornanediyl group, a tricyclodecanediyl group, a tetracyclododecandiyl group, and an adamantanediyl group.

  As the structural unit (2), for example, structural units represented by the following formulas (II-1) to (II-20) are preferable. Among these structural units (2), (II-1), (II-2), (II-3), (II-4), (II-5), (II-6), (II-8) ), (II-9), (II-11), (II-12), (II-13), (II-14), (II-15), (II-16), (II-17), (II-19) is more preferred. These may be used alone or in combination of two or more.

(In formulas (II-1) to (II-20), R ³ has the same meaning as defined in formula (II) above.)

  The content of the structural unit (2) is preferably 5 mol% to 80 mol%, more preferably 10 mol% to 80 mol%, and particularly preferably 20 mol% to 70 mol% with respect to all the structural units constituting the polymer [A]. . When the content of the structural unit (2) is within the above range, the resolution as a resist is improved, and the sensitivity and the exposure margin are both excellent.

  The polymer [A] is at least selected from, for example, a structural unit containing a lactone structure represented by the following formulas (III-1) to (III-6) and a structural unit (3) containing a cyclic carbonate structure. It is preferable to have one.

(In (III-1) to (III-6), R ⁷ and R ⁸ are each independently a hydrogen atom or a methyl group, R ⁹ is a hydrogen atom or a methoxy group, and A is a single atom. A bond or a methylene group, B is a methylene group or an oxygen atom, and a and b are each independently an integer of 0 to 2.)

  When the polymer [A] further has the structural unit (3), the radiation-sensitive resin composition can exhibit resist characteristics in which sensitivity, resolution, and exposure margin are highly balanced. In addition, synergistic effects that improve developability as a resist, defect properties, temperature dependency of low PEB, and the like are exhibited.

  As the structural unit (3), for example, structural units represented by the following formulas (III-1a) to (III-6) are preferable. These may be used alone or in combination of two or more.

(In formulas (III-1a) to (III-6), R ⁷ has the same definition as that defined in formula (3) above.)

  The content of the structural unit (3) is preferably 0 mol% to 70 mol%, more preferably 0 mol% to 60 mol%, based on all the structural units constituting the polymer [A]. By making the content rate of a structural unit into the said range, the developability as a resist, defect property, low PEB temperature dependence, etc. can be improved. In addition, when the content rate of a structural unit (3) exceeds 70 mol%, there exists a possibility that the resolution as a resist may fall.

  The polymer [A] may further contain, for example, one or more structural units represented by the following formula.

(In the formula, R ¹⁰ is a hydrogen atom or a methyl group.)

Furthermore, the polymer [A] includes, for example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate, and (meth) acrylic acid. -Bicyclo [2.2.1] heptyl ester, (meth) acrylic acid-cyclohexyl ester, (meth) acrylic acid-bicyclo [4.4.0] decanyl ester, (meth) acrylic acid-bicyclo [2.2 .2] Octyl ester, (meth) acrylic acid-tricyclo [5.2.1.0 ^2,6 ] decanyl ester, (meth) acrylic acid-adamantyl, (meth) acrylic acid-tricyclo [3.3.1]. ^.1,3,7 ] may contain a structural unit derived from alkyl (meth) acrylate such as decanyl ester.

  The radiation sensitive resin composition of the present invention is characterized by containing a polymer [A] as a base polymer. The base polymer may be the polymer [A] alone or a mixture of the polymer [A] and another polymer. The other polymer does not contain the structural unit (1) and is selected from the group consisting of the above-mentioned other structural units (structural unit (2), structural unit (3), structural unit (4), and other structural units). The polymer containing at least one selected from the above is preferably used. Moreover, another polymer can be used individually by 1 type or in mixture of 2 or more types.

  In the base polymer used in the positive-type radiation-sensitive resin composition, the content of the structural unit (2) in the total structural unit of the total polymer including the polymer [A] and other polymers to be included as necessary The rate is preferably 20% by mass to 70% by mass, and particularly preferably 20% by mass to 60% by mass. When the structural unit (2) is 20% by mass or more, the base polymer is an alkali-insoluble or hardly alkali-soluble polymer and has a property of being alkali-soluble in the presence of an acid generated by exposure.

The polymer [A] can be synthesized according to a conventional method such as radical polymerization. For example,
A method in which a solution containing a monomer and a radical initiator is dropped into a reaction solvent or a solution containing a monomer to cause a polymerization reaction;
A method in which a solution containing a monomer and a solution containing a radical initiator are separately dropped into a reaction solvent or a solution containing a monomer to cause a polymerization reaction;
A plurality of types of solutions containing each monomer and a solution containing a radical initiator are separately added to a reaction solvent or a solution containing a monomer and synthesized by a method such as a polymerization reaction. It is preferable.

  In addition, when the monomer solution is dropped and reacted with respect to the monomer solution, the amount of the monomer in the dropped monomer solution is 30 mol% with respect to the total amount of monomers used for polymerization. The above is preferable, 50 mol% or more is more preferable, and 70 mol% or more is particularly preferable.

  What is necessary is just to determine the reaction temperature in these methods suitably with initiator seed | species. Usually, it is 30 degreeC-150 degreeC, 40 degreeC-150 degreeC is preferable, and 50 degreeC-140 degreeC is further more preferable. The dropping time varies depending on the reaction temperature, the type of initiator, the monomer to be reacted, etc., but is usually 30 minutes to 8 hours, preferably 45 minutes to 6 hours, and more preferably 1 hour to 5 hours. . Further, the total reaction time including the dropping time varies depending on the conditions as in the dropping time, but is usually 30 minutes to 12 hours, preferably 45 minutes to 12 hours, and more preferably 1 to 10 hours.

  Examples of the radical initiator used for the polymerization include azobisisobutyronitrile (hereinafter also referred to as “AIBN”), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2 2,2′-azobis (2-cyclopropylpropionitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), and the like. These initiators can be used alone or in admixture of two or more.

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

  The resin obtained by the polymerization reaction is preferably recovered by a reprecipitation method. That is, after completion of the polymerization reaction, the target resin is recovered as a powder by introducing the polymerization solution into a reprecipitation solvent. As the reprecipitation solvent, alcohols or alkanes can be used alone or in admixture of two or more. In addition to the reprecipitation method, the resin can be recovered by removing low-molecular components such as monomers and oligomers by a liquid separation operation, a column operation, an ultrafiltration operation, or the like.

  The polystyrene-converted weight average molecular weight (hereinafter also referred to as “Mw”) of the polymer [A] by gel permeation chromatography (hereinafter also referred to as GPC) is not particularly limited, but is 1,000 or more and 100,000 or less. Is preferable, 1,000 or more and 30,000 or less are more preferable, and 1,000 or more and 20,000 or less are particularly preferable. In addition, when Mw of the polymer [A] is less than 1,000, heat resistance when used as a resist tends to be lowered. On the other hand, when the Mw of the polymer [A] exceeds 100,000, the developability when used as a resist tends to be lowered.

  Further, the ratio (Mw / Mn) of Mw to the polystyrene-equivalent number average molecular weight (hereinafter also referred to as “Mn”) by GPC of the polymer [A] is usually 1.0 or more and 5.0 or less, 1.0 or more and 3.0 or less are preferable and 1.0 or more and 2.0 or less are more preferable.

  Mw and Mn in this specification are GPC columns (Tosoh Corp., 2 G2000HXL, 1 G3000HXL, 1 G4000HXL), flow conditions of 1.0 ml / min, elution solvent tetrahydrofuran, column temperature of 40 ° C. The value measured by GPC using monodisperse polystyrene as a standard.

  The said radiation sensitive resin composition may use the said polymer [A] individually or in combination of 2 or more types. In addition, the polymer [A] may be mixed with another polymer having at least one selected from the structural unit (2), the structural unit (3), and other structural units.

(Acid generator [B])
The acid generator [B] generates an acid by exposure, dissociates an acid dissociable group present in the polymer [A] by the acid, and generates an acid. As a result, the polymer [A] becomes readily soluble in the alkali developer. The inclusion form of the acid generator [B] in the radiation-sensitive resin composition may be a compound form as described later or a form incorporated as a part of the polymer [A] or the other polymer described above. Both of these forms may be used.

  Examples of the acid generator [B] include onium salt compounds, sulfonimide compounds, halogen-containing compounds, diazoketone compounds, and the like. Of these acid generators [B], onium salt compounds are preferred.

  Examples of the onium salt compounds include sulfonium salts (including tetrahydrothiophenium salts), iodonium salts, phosphonium salts, diazonium salts, pyridinium salts, and the like. Of these onium salt compounds, sulfonium salts are preferred.

  Examples of the sulfonium salt include triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium perfluoro-n-octanesulfonate, triphenylsulfonium 2-bicyclo [2.2.1] hept. 2-yl-1,1,2,2-tetrafluoroethanesulfonate, triphenylsulfonium camphorsulfonate, 4-cyclohexylphenyldiphenylsulfonium trifluoromethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4- Cyclohexylphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-cyclohexylphenyldiphenyl Rusulfonium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 4-cyclohexylphenyldiphenylsulfonium camphorsulfonate, 4-methanesulfonylphenyldiphenylsulfonium trifluoromethanesulfonate 4-methanesulfonylphenyldiphenylsulfonium nonafluoro-n-butanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium 2-bicyclo [2.2.1] hept- 2-yl-1,1,2,2-tetrafluoroethanesulfonate, 4-methanesulfonylphenyldiphenylsulfonium camphorsulfonate, etc. It is. Of these, triphenylsulfonium trifluoromethanesulfonate and triphenylsulfonium nonafluoro-n-butanesulfonate are preferable, and triphenylsulfonium nonafluoro-n-butanesulfonate is more preferable.

  Examples of the tetrahydrothiophenium salt include 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium. Nonafluoro-n-butanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothio Phenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium camphor Sulfonate, 1- (6-n-butoxynaphthalen-2-yl) Tetrahydrothiophenium trifluoromethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothio Phenium perfluoro-n-octanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2, 2-tetrafluoroethanesulfonate, 1- (6-n-butoxynaphthalen-2-yl) tetrahydrothiophenium camphorsulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (3,5-dimethyl- -Hydroxyphenyl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (3,5-dimethyl -4-hydroxyphenyl) tetrahydrothiophenium 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (3,5-dimethyl-4- Hydroxyphenyl) tetrahydrothiophenium camphorsulfonate and the like. Of these tetrahydrothiophenium salts, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) Tetrahydrothiophenium perfluoro-n-octane sulfonate and 1- (3,5-dimethyl-4-hydroxyphenyl) tetrahydrothiophenium nonafluoro-n-butane sulfonate are preferred.

  Examples of the iodonium salt include diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium perfluoro-n-octanesulfonate, diphenyliodonium 2-bicyclo [2.2.1] hept-2-yl. -1,1,2,2-tetrafluoroethanesulfonate, diphenyliodonium camphorsulfonate, bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate, bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate Bis (4-t-butylphenyl) iodonium perfluoro-n-octanesulfonate, bis (4-t-butylphenyl) iodonium 2-bicyclo [2. .1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, bis (4-t- butylphenyl) iodonium camphorsulfonate, and the like. Of these iodonium salts, bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate is preferred.

Examples of the sulfonimide compound include N- (trifluoromethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (nonafluoro-n-butanesulfonyloxy) bicyclo. [2.2.1] Hept-5-ene-2,3-dicarboximide, N- (perfluoro-n-octanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3 -Dicarboximide, N- (2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonyloxy) bicyclo [2.2.1] hept-5 ene-2,3-dicarboximide, N- (2- (3- tetracyclo ^[4.4.0.1 2,5 ^{.1 7,10]} dodecanyl) -1,1-difluoroethanesulfonate two Ruoxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide, N- (camphorsulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-di Carboximide etc. can be mentioned. Of these sulfonimide compounds, N- (trifluoromethanesulfonyloxy) bicyclo [2.2.1] hept-5-ene-2,3-dicarboximide is preferred.

  The acid generator [B] can be used alone or in combination of two or more. The amount of the acid generator [B] used is usually 0.1 parts by mass or more and 10 parts by mass or less, preferably 100 parts by mass or less with respect to 100 parts by mass of the polymer [A], from the viewpoint of ensuring sensitivity and developability as a resist. Is 0.5 parts by mass or more and 9 parts by mass or less. In this case, if the amount of the acid generator [B] used is less than 0.1 parts by mass, the sensitivity and developability tend to decrease. On the other hand, if it exceeds 10 parts by mass, the transparency to radiation decreases and the rectangular shape It tends to be difficult to obtain a resist pattern.

(Optional component)
In addition to the polymer [A] and the acid generator [B], the radiation-sensitive resin composition of the present invention includes a fluorine-containing resin and an alicyclic skeleton as optional components as long as the effects of the present invention are not impaired. A compound, a surfactant, an acid diffusion controller, a sensitizer, a solvent and the like can be contained. The compounding quantity of an arbitrary component can be suitably determined according to the purpose.

(Fluorine-containing resin)
The fluorine-containing resin exhibits an action of developing water repellency on the resist film surface particularly in immersion exposure. In addition, it has the effect of suppressing elution of components from the resist film to the immersion liquid, and even when immersion exposure is performed by high-speed scanning, it does not leave droplets, resulting in immersion-derived defects such as watermark defects. There is an effect to suppress.

As the structure of the fluorine-containing resin, for example,
A fluorine-containing resin which itself is insoluble in a developer and becomes alkali-soluble by the action of an acid;
A fluorine-containing resin which is itself soluble in a developer and whose alkali solubility is increased by the action of an acid;
A fluorine-containing resin which itself is insoluble in a developer and becomes alkali-soluble by the action of alkali;
Examples thereof include a fluorine-containing resin which is itself soluble in a developer and whose alkali solubility is increased by the action of an alkali.

  As the fluorine-containing resin, a polymer having a fluorine-containing structural unit is preferable. Examples of the monomer that gives a fluorine-containing structural unit include trifluoromethyl (meth) acrylate, 2,2,2-trifluoroethyl (meth) acrylate, perfluoroethyl (meth) acrylate, Perfluoro n-propyl (meth) acrylic acid ester, perfluoro i-propyl (meth) acrylic acid ester, perfluoro n-butyl (meth) acrylic acid ester, perfluoro i-butyl (meth) acrylic acid ester, perfluoro t-butyl (meth) acrylic acid ester, 2- (1,1,1,3,3,3-hexafluoropropyl) (meth) acrylic acid ester, 1- (2,2,3,3,4,4 , 5,5-octafluoropentyl) (meth) acrylic acid ester, perfluorocyclohexylmethyl (meth) Crylate ester, 1- (2,2,3,3,3-pentafluoropropyl) (meth) acrylic ester, 1- (3,3,4,4,5,5,6,6,7,7 , 8,8,9,9,10,10,10-heptadecafluorodecyl) (meth) acrylic acid ester, 1- (5-trifluoromethyl-3,3,4,4,5,6,6, 6-octafluorohexyl) (meth) acrylic acid ester and the like.

  As the fluorine-containing resin, for example, a copolymer having the fluorine-containing structural unit and a structural unit constituting the polymer [A] is preferable. These fluorine-containing resins can be used alone or in combination of two or more.

(Alicyclic skeleton-containing compound)
The alicyclic skeleton-containing compound has an effect of improving dry etching resistance, pattern shape, adhesion to the substrate, and the like.

Examples of the alicyclic skeleton-containing compound include adamantane derivatives such as 1-adamantanecarboxylic acid, 2-adamantanone, and 1-adamantanecarboxylate t-butyl;
Deoxycholic acid esters such as t-butyl deoxycholate, t-butoxycarbonylmethyl deoxycholic acid, 2-ethoxyethyl deoxycholic acid;
Lithocholic acid esters such as t-butyl lithocholic acid, t-butoxycarbonylmethyl lithocholic acid, 2-ethoxyethyl lithocholic acid;
3- [2-Hydroxy-2,2-bis (trifluoromethyl) ethyl] tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodecane, 2-hydroxy-9-methoxycarbonyl-5-oxo-4-oxa-tricyclo [4.2.1.0 ^3,7 ] nonane, and the like. These alicyclic skeleton-containing compounds can be used alone or in combination of two or more.

(Surfactant)
Surfactants have the effect of improving coatability, striation, developability, and the like.

  Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene n-octylphenyl ether, polyoxyethylene n-nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol In addition to nonionic surfactants such as distearate, KP341 (Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (Kyoeisha Chemical Co., Ltd.), Ftop EF301 (Tochem Products), Ftop EF303 (Tochem Products), Ftop EF352 (Tochem Products), MegaFuck F171 (Dainippon Ink and Chemicals), Mega Fax F173 (Dainippon Ink and Chemicals), Florard FC430 (Sumitomo 3M), Florard FC431 (Sumitomo 3M), Asahi Guard AG710, Surflon S-382 (Asahi Glass Industry), Surflon SC-101 (Asahi Glass Industry) Surflon SC-102 (Asahi Glass Industrial Co., Ltd.), Surflon SC-103 (Asahi Glass Industrial Co., Ltd.), Surflon SC-104 (Asahi Glass Industrial Co., Ltd.), Surflon SC-105 (Asahi Glass Industrial Co., Ltd.), Surflon SC-106 (Asahi Glass Industrial Co., Ltd.) Etc. These surfactants can be used alone or in combination of two or more.

(Acid diffusion controller)
The acid diffusion controller controls the diffusion phenomenon in the resist film of the acid generated from the acid generator [B] by exposure, has the effect of suppressing undesirable chemical reaction in the non-exposed region, and the resulting radiation sensitive resin composition The storage stability of the product is further improved, the resolution of the resist is further improved, and the change in the line width of the resist pattern due to fluctuations in the holding time from exposure to development processing can be suppressed, which greatly improves process stability. An excellent composition is obtained. The inclusion form of the acid diffusion controller in the radiation-sensitive resin composition may be a free compound form, a form incorporated as part of the polymer [A], or both forms.

  In addition to the structural unit (1) in the polymer [A], the radiation-sensitive resin composition of the present invention further contains a low-molecular nitrogen-containing compound as another acid diffusion controller unless the effects of the present invention are impaired. You may contain. As this nitrogen-containing compound, for example, a nitrogen-containing compound represented by the following formula can be suitably used.

(In the formula, R ¹¹ and R ¹² are each independently a hydrogen atom or a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, an aryl group or an aralkyl group, and these are substituents. Or a divalent saturated or unsaturated hydrocarbon group having 4 to 20 carbon atoms or a derivative thereof, together with the carbon atoms to which R ^{11 and} R ¹² are bonded to each other. May be formed.)

  Examples of the nitrogen-containing compound represented by the above formula 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-amyloxycarbonyl-4-hydroxypiperidi N-N-butoxycarbonylpyrrolidine, N, N′-di-t-butoxycarbonylpiperazine, N, N-di-t-butoxycarbonyl-1-adamantylamine, N, N-di-t-butoxycarbonyl-N -Methyl-1-adamantylamine, Nt-butoxycarbonyl-4,4'-diaminodiphenylmethane, N, N'-di-t-butoxycarbonylhexamethylenediamine, N, N, N ', N'-tetra- t-butoxycarbonylhexamethylenediamine, N, N′-di-t-butoxycarbonyl-1,7-diaminoheptane, N, N′-di-t-butoxycarbonyl-1,8-diaminooctane, N, N ′ -Di-t-butoxycarbonyl-1,9-diaminononane, N, N'-di-t-butoxycarbonyl-1,10-diamino N, N′-di-t-butoxycarbonyl-1,12-diaminododecane, N, N′-di-t-butoxycarbonyl-4,4′-diaminodiphenylmethane, Nt-butoxycarbonylbenzimidazole, Examples include Nt-alkylalkoxycarbonyl group-containing amino compounds such as Nt-butoxycarbonyl-2-methylbenzimidazole and Nt-butoxycarbonyl-2-phenylbenzimidazole.

  In addition to the nitrogen-containing compound represented by the above formula, examples of the nitrogen-containing compound include a tertiary amine compound, a quaternary ammonium hydroxide compound, a photodegradable base compound, and other nitrogen-containing heterocyclic compounds. be able to.

As the tertiary amine compound, for example,
Triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-pentylamine, tri-n-hexylamine, tri-n-heptylamine, tri-n-octylamine, cyclohexyldimethylamine, dicyclohexylmethylamine , Tri (cyclo) alkylamines such as tricyclohexylamine;
Fragrances such as aniline, N-methylaniline, N, N-dimethylaniline, 2-methylaniline, 3-methylaniline, 4-methylaniline, 4-nitroaniline, 2,6-dimethylaniline, 2,6-diisopropylaniline Group amines;
Alkanolamines such as triethanolamine and N, N-di (hydroxyethyl) aniline;
N, N, N ′, N′-tetramethylethylenediamine, N, N, N ′, N′-tetrakis (2-hydroxypropyl) ethylenediamine, 1,3-bis [1- (4-aminophenyl) -1- Methylethyl] benzenetetramethylenediamine, bis (2-dimethylaminoethyl) ether, bis (2-diethylaminoethyl) ether, and the like.

  Examples of the quaternary ammonium hydroxide compound include tetra-n-propylammonium hydroxide and tetra-n-butylammonium hydroxide.

  The above-mentioned other acid diffusion inhibitors can be used singly or in combination of two or more. The content ratio of the low molecular acid diffusion controller is preferably less than 5 parts by mass, more preferably less than 1 part by mass with respect to 100 parts by mass of the total polymer. When the total amount used exceeds 5 parts by mass, the sensitivity as a resist tends to be remarkably lowered.

(Sensitizer)
The sensitizer absorbs energy other than the energy of the radiation absorbed by the acid generator [B], and transmits the energy to the acid generator [B] in the form of a radical, for example. The effect of increasing the production amount is exhibited, and the effect of improving the “apparent sensitivity” of the radiation-sensitive resin composition is exhibited.

  Examples of the sensitizer include carbazoles, acetophenones, benzophenones, naphthalenes, phenols, biacetyl, eosin, rose bengal, pyrenes, anthracenes, and phenothiazines. These sensitizers can be used alone or in combination of two or more.

(solvent)
The radiation sensitive resin composition usually contains a solvent. A solvent will not be specifically limited if said polymer [A], an acid generator [B], and an arbitrary component can be melt | dissolved at least. Examples thereof include alcohol solvents, ketone solvents, amide solvents, ether solvents, ester solvents, and mixed solvents thereof.

As an alcohol solvent, for example,
Methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, tert-butanol, n-pentanol, iso-pentanol, 2-methylbutanol, sec-pentanol, tert- Pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, sec-hexanol, 2-ethylbutanol, sec-heptanol, 3-heptanol, n-octanol, 2-ethylhexanol, sec-octanol, n- Nonyl alcohol, 2,6-dimethyl-4-heptanol, n-decanol, sec-undecyl alcohol, trimethylnonyl alcohol, sec-tetradecyl alcohol, sec-heptadecyl alcohol, furf Alcohol, phenol, cyclohexanol, methyl cyclohexanol, 3,3,5-trimethyl cyclohexanol, benzyl alcohol, mono-alcohol solvents such as diacetone alcohol;
Ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol, 2 -Polyhydric alcohol solvents such as ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol;
Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene glycol mono-2-ethylbutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl Ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol Monomethyl ether, dipropylene glycol monoethyl ether, polyhydric alcohol partial ether solvents such as dipropylene glycol monopropyl ether.

  Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-iso-butyl ketone, methyl-n-pentyl ketone, ethyl-n-butyl ketone, and methyl-n. -Ketones such as hexyl ketone, di-iso-butyl ketone, trimethylnonanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone, diacetone alcohol, acetophenone And system solvents.

  Examples of amide solvents include N, N′-dimethylimidazolidinone, N-methylformamide, N, N-dimethylformamide, N, N-diethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide. , N-methylpropionamide, N-methylpyrrolidone and the like.

  Examples of the ester solvent include diethyl carbonate, propylene carbonate, methyl acetate, ethyl acetate, γ-butyrolactone, γ-valerolactone, n-propyl acetate, iso-propyl acetate, n-butyl acetate, iso-butyl acetate, acetic acid. sec-butyl, n-pentyl acetate, sec-pentyl acetate, 3-methoxybutyl acetate, methyl pentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, benzyl acetate, cyclohexyl acetate, methyl cyclohexyl acetate, n-nonyl acetate, aceto Methyl acetate, ethyl acetoacetate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene acetate Recall mono-n-butyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, diacetic acid Glycol, methoxytriglycol acetate, ethyl propionate, n-butyl propionate, iso-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate , Diethyl malonate, dimethyl phthalate, diethyl phthalate and the like.

Other solvents include, for example,
Aliphatic carbonization such as n-pentane, iso-pentane, n-hexane, iso-hexane, n-heptane, iso-heptane, 2,2,4-trimethylpentane, n-octane, iso-octane, cyclohexane, methylcyclohexane A hydrogen-based solvent;
Fragrances such as benzene, toluene, xylene, mesitylene, ethylbenzene, trimethylbenzene, methylethylbenzene, n-propylbenzene, iso-propylbenzene, diethylbenzene, iso-butylbenzene, triethylbenzene, di-iso-propylbenzene and n-amylnaphthalene Group hydrocarbon solvents;
Examples include halogen-containing solvents such as dichloromethane, chloroform, chlorofluorocarbon, chlorobenzene, and dichlorobenzene.

  Among these solvents, propylene glycol monomethyl ether acetate, cyclohexanone and γ-butyrolactone are preferable. These solvents can be used alone or in combination of two or more.

  The radiation sensitive resin composition has a positive radiation sensitive property. The positive radiation sensitive composition can be prepared, for example, by mixing the polymer [A], the acid generator [B], and an optional component in a predetermined ratio in an organic solvent. The positive radiation sensitive composition can be prepared and used in a state dissolved or dispersed in a suitable organic solvent.

(Other optional ingredients)
Other optional components include, for example, dyes, pigments, adhesion aids, alkali-soluble resins, low-molecular alkali solubility control agents having acid-dissociable protecting groups, antihalation agents, storage stabilizers, antifoaming agents. Etc. Among these, for example, when a dye or a pigment is blended, the latent image of the exposed portion can be visualized, and the influence of halation during exposure can be reduced. Further, when an adhesion assistant is blended, the adhesion to the substrate can be improved. These other optional components can be used alone or in combination of two or more.

(Photoresist pattern formation method)
As a method for forming a photoresist pattern, for example, the following method is generally used. Using the radiation-sensitive resin composition, a step of forming a photoresist film on the substrate (hereinafter also referred to as step (i)), the formed photoresist film through an immersion medium as necessary, It is also referred to as a step of exposing by exposure to radiation through a mask having a predetermined pattern (hereinafter also referred to as step (ii)) and a step of heating the substrate (exposed photoresist film) (hereinafter referred to as step (iii)). ) And a development step (hereinafter also referred to as step (iv)), a photoresist pattern can be formed.

  In the step (i), a radiation sensitive resin composition or a composition solution obtained by dissolving it in a solvent is applied to a substrate (silicon wafer, silicon dioxide) by coating means such as spin coating, cast coating, roll coating or the like. A photoresist film is formed by volatilizing the solvent in the coating film by applying a resin composition solution to a predetermined film thickness on a wafer coated with an antireflection film, etc., and then pre-baking. To do.

  In step (ii), the photoresist film formed in step (i) is irradiated with radiation (possibly through an immersion medium such as water) and exposed. At this time, radiation is irradiated through a mask having a predetermined pattern. As the radiation, irradiation is performed by appropriately selecting from visible light, ultraviolet light, far ultraviolet light, X-rays, charged particle beams and the like according to the line width of the target pattern. Far ultraviolet rays represented by ArF excimer laser (wavelength 193 nm) and KrF excimer laser (wavelength 248 nm) are preferable, and ArF excimer laser is more preferable.

  Step (iii) is called PEB and is a step in which the acid generated from the acid generator [B] deprotects the polymer in the exposed portion of the photoresist film in step (ii). PEB is usually carried out by appropriately selecting in the range of 50 ° C to 180 ° C.

  In step (iv), the exposed photoresist film is developed with a developer to form a predetermined photoresist pattern. After development, it is common to wash with water and dry. Examples of the developer include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, Ethyldimethylamine, triethanolamine, tetramethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo- [5.4.0] -7-undecene, 1,5-diazabicyclo- [4.3.0 An alkaline aqueous solution in which at least one alkaline compound such as -5-nonene is dissolved is preferable.

  In addition, when performing immersion exposure, before the step (ii), in order to protect the direct contact between the immersion liquid and the resist film, an immersion liquid insoluble immersion protective film is formed on the resist film. It may be provided. Examples of the immersion protective film include a solvent-peelable protective film (see, for example, JP-A-2006-227632) that is peeled off by a solvent before the step (iv), and a development that peels off simultaneously with the development in the step (iv). Any of liquid-removable protective films (see, for example, WO2005-069096 and WO2006-035790) may be used. However, from the viewpoint of throughput, it is preferable to use a developer peeling type immersion protective film.

  The resist pattern obtained in this way has a good rectangularity with a top loss prevented, and is suitable for fine processing using a lithography technique.

  EXAMPLES Hereinafter, although this invention is explained in full detail based on an Example, this invention is not interpreted limitedly based on description of this Example.

  Each radiation sensitive resin composition of an Example and a comparative example is synthesize | combined by using either single or 2 types or more together among resin A-1 to A-4 mentioned later. Resins A-1 to A-4 are synthesized by using any one of the following monomers M-1 to M-5 alone or in combination of two or more.

M-1: 1-methyladamantyl methacrylate M-2: a monomer represented by the following formula

M-3: monomer represented by the following formula

M-4: 4-oxa-5-oxo-tricyclo [4,2,1,0 ^3,7] nonane-2-yl methacrylate

M-5: a monomer represented by the following formula

Example 1
Synthesis of Resin A-1 Monomer M-1 (17.55 g, 60 mol%), Monomer M-2 (2.49 g, 10 mol%) and Monomer M-3 (9.97 g, 30 mol%) Was dissolved in 60 g of 2-butanone, and AIBN (1.02 g, 5 mol% based on the total number of moles of monomers M-1, M-2 and M-3) was added as an initiator, Prepared. Next, 30 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 600 g of methanol, and the precipitated white powder was separated by filtration. The white powder separated by filtration was washed twice as a slurry with 120 g of methanol. Thereafter, the residue was filtered off and dried at 60 ° C. for 17 hours to obtain a white powder copolymer, resin A-1 (19.6 g, yield 65%, Mw = 4,400, Mw / Mn = 1.27). As a result of ¹³ C-NMR analysis of the resin A-1, the content ratio of the structural unit derived from the monomer M-1: the structural unit derived from the monomer M-2: the structural unit derived from the monomer M-3 is: It was 57.5: 10.1: 32.4 (mol%). The ¹³ C-NMR analysis was measured using a nuclear magnetic resonance apparatus (JEOL Ltd., JNM-ECX400). ^The peaks used for calculating the composition ratio in ¹³ C-NMR analysis are as follows.

Structural unit derived from (M-1): δ 86.55 (1C)
Structural unit derived from (M-2): δ 171.03 (1C)
Structural unit derived from (M-3): δ 157.85 (1C)

(Synthesis Example 1)
Synthesis of Resin A-2 Monomer M-1 (11.38 g, 60 mol%) and monomer M-3 (8.62 g, 40.0 mol%) were dissolved in 40 g of 2-butanone, and AIBN was used as an initiator. (0.66 g, 5 mol% with respect to the total number of moles of monomers M-1 and M-3) was added to prepare a monomer solution. Next, 20 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 400 g of 2-propanol, and the precipitated white powder was separated by filtration. The white powder separated by filtration was washed twice as a slurry with 80 g of methanol. Thereafter, the residue was filtered off and dried at 60 ° C. for 17 hours to obtain a white powder polymer, resin A-2 (13.4 g, yield 68%, MW = 6,800, Mw / Mn = 1.35). As a result of ¹³ C-NMR analysis of Resin A-2, the content ratio of the structural unit derived from monomer M-1 to the structural unit derived from monomer M-3 was 54.5: 45.5 (mol%). Met.

(Synthesis Example 2)
Synthesis of Resin A-3 Monomer M-1 (18.38 g, 60 mol%) and monomer M-4 (11.62 g, 40.0 mol%) were dissolved in 2-butanone 60 g, and AIBN was used as an initiator. (1.07 g, 5 mol% with respect to the total number of moles of monomers M-1 and M-4) was added to prepare a monomer solution. Next, 30 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 600 g of hexane, and the precipitated white powder was separated by filtration. The white powder separated by filtration was washed twice with 120 g of 2-propanol as a slurry. Thereafter, the residue was filtered off and dried at 60 ° C. for 17 hours to obtain a white powder polymer, resin A-3 (21.3 g, yield 71%, Mw = 5,400, Mw / Mn = 1.65). As a result of ¹³ C-NMR analysis of Resin A-3, the content ratio of the structural unit derived from monomer M-1 to the structural unit derived from monomer M-4 was 55.4: 45.6 (mol%). Met.

(Synthesis Example 3)
Synthesis of Resin A-4 Monomer M-1 (17.87 g, 60 mol%), Monomer M-5 (1.97 g, 10 mol%), Monomer M-3 (10.16 g, 30 mol%) Is dissolved in 60 g of 2-butanone, and AIBN (1.04 g, 5 mol% with respect to the total number of moles of monomers M-1, M-3 and M-5) is added as an initiator to prepare a monomer solution. did. Next, 30 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 put into 600 g of 2-propanol, and the precipitated white powder was separated by filtration. The white powder separated by filtration was washed twice as a slurry with 120 g of methanol. Thereafter, the residue was filtered off and dried at 60 ° C. for 17 hours to obtain a white powder polymer, resin A-4 (19.0 g, yield 63%, Mw = 4,200, Mw / Mn = 1.23). As a result of ¹³ C-NMR analysis of resin A-4, the content ratio of the structural unit derived from monomer M-1: the structural unit derived from monomer M-5: the structural unit derived from monomer M-3 is: It was 56.9: 9.9: 33.2 (mol%).

(Preparation of radiation-sensitive resin composition)
Details of the acid generator, the acid diffusion controller and the solvent constituting the radiation sensitive resin composition other than the resins A-1 to A-4 are shown below.

(Acid generator)
Triphenylsulfonium nonafluorobutane sulfonate

(Acid diffusion controller)
Nt-butoxycarbonyl-4-hydroxypiperidine

(solvent)
S-1: Propylene glycol monomethyl ether acetate S-2: Cyclohexanone S-3: γ-butyrolactone

(Example 2)
Resin A-1 (50 mass parts), Resin A-2 (50 mass parts) and acid generation in solvent S-1 (900 mass parts), S-2 (390 mass parts) and S-3 (30 mass parts) What mixed the body (8.4 mass parts) was dissolved, and the obtained mixed solution was filtered with the filter of the hole diameter 0.20 micrometer, and the radiation sensitive resin composition was obtained.

(Comparative Examples 1-4)
Except having changed the kind of resin which comprises polymer [A], and the compounding quantity of the acid diffusion control body into the kind shown in Table 1, it operated similarly to Example 2 and obtained the radiation sensitive resin composition. It was.

  About the radiation sensitive resin composition of Example 2 and Comparative Examples 1-4, the following performance evaluation was performed using an ArF excimer laser as a light source. The results are shown in Table 1.

(Measurement of sensitivity)
A lower antireflection film having a thickness of 77 nm was formed on the surface of an 8-inch wafer using a lower antireflection film forming agent (Nissan Chemical Co., ARC29A). Example 2 and Comparative Examples 1 to 4 were applied to the surface of this substrate by spin coating, and soft baking was performed on a hot plate at 100 ° C. for 60 seconds to form a resist film having a thickness of 150 nm.

  This resist film was exposed through a mask pattern using a full-field reduction projection exposure apparatus (Nikon Corporation, S306C, numerical aperture 0.78). Thereafter, PEB was performed for 60 seconds at the temperature shown in Table 1, and then developed with a 2.38 mass% tetramethylammonium hydroxide aqueous solution at 25 ° C. for 30 seconds, washed with water and dried to form a positive resist pattern. Formed.

At this time, the line width formed through a one-to-one line and space mask with a dimension of 75 nm is the exposure amount (mJ / cm ² ) formed in a one-to-one line and space with a line width of 75 nm. The optimum exposure dose was taken as the sensitivity (mJ / cm ² ). Note that a scanning electron microscope (Hitachi High-Technologies Corporation, S9260) was used for length measurement.

(Resolution measurement)
The dimension of the smallest one-to-one line-and-space pattern that can be resolved at the optimum exposure amount was defined as the resolution (nm).

(Exposure margin measurement)
Exposure amount when the line width is 67.9 nm (−10% of 75 nm) when exposed through a mask of a one-to-one line and space pattern with a line width of 75 nm, and 82.5 nm (+ 10% of 75 nm) ), The absolute value of the difference in exposure amount is divided by the sensitivity and multiplied by 100 to obtain the exposure margin (%). The larger the exposure margin, the better the radiation-sensitive resin composition is excellent in process stability. The scanning electron microscope was used to observe the pattern dimensions.

(Evaluation)
From Table 1, it is suggested that Example 2 exhibits better sensitivity, resolution, and exposure margin than Comparative Examples 1 to 4.

  The radiation-sensitive resin composition of the present invention can exhibit superior sensitivity, resolution, and exposure margin as compared with conventional radiation-sensitive resin compositions. Therefore, as a chemically amplified radiation-sensitive resin composition sensitive to actinic radiation with a short wavelength, it is possible to produce a product without causing development defects during microfabrication, and the integration is expected to be further refined in the future. It can be suitably used in the field of circuit elements and the like.

Claims (4)

[A] A polymer having a structural unit represented by the following formula (I), and [B] a radiation-sensitive resin composition containing a radiation-sensitive acid generator.

(In Formula (I), R ¹ is a hydrogen atom or a methyl group. R ² is a hydrocarbon group having 1 to 20 carbon atoms.) The radiation sensitive resin composition according to claim 1, wherein R ² in the formula (I) is an alkanediyl group having 1 to 4 carbon atoms. The radiation sensitive resin composition according to claim 1 or 2, wherein the polymer [A] further has a structural unit represented by the following formula (II).

(In the formula (II), ^{R 3} is, .R ⁴ is a hydrogen atom or a methyl group, a monovalent alicyclic hydrocarbon group having an alkyl group or 4 to 20 carbon atoms having 1 to 4 carbon atoms. R ⁵ and R ⁶ are each independently an alkyl group having 1 to 4 carbon atoms or a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms, or R ⁵ and R ⁶ are bonded to each other. And a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms together with the carbon atom to which they are bonded.)   The sensation according to any one of claims 1, 2 and 3, wherein the polymer [A] further has at least one selected from a structural unit containing a lactone structure and a structural unit containing a cyclic carbonate structure. Radiation resin composition.