WO2012023349A1 - Pattern-forming method and radiation-sensitive resin composition - Google Patents

Abstract

The present invention is a trench pattern-forming or hole pattern-forming method comprising (1) a step for forming a resist film in which a radiation-sensitive resin composition is applied to a substrate, (2) an exposure step in which radiation is irradiated onto the resist film via a photomask, and (3) a development step in which the exposed resist film is developed, wherein the trench pattern-forming or hole pattern-forming method is characterized in that the radiation-sensitive resin composition comprises: [A] a polymer containing 10 mol% or less of structural units having acid-dissociating groups; [B] a polymer containing more than 10 mol% of structural units having acid-dissociating groups; and [C] a radiation-sensitive acid generator, and the development solution for the development step (3) comprises 80 mass% or more of an organic solvent.

Description

Pattern forming method and radiation-sensitive resin composition

The present invention relates to a pattern forming method and a radiation sensitive resin composition.

With the miniaturization of various electronic device structures such as semiconductor devices and liquid crystal devices, miniaturization of resist patterns in the lithography process is required. At present, a fine resist pattern having a line width of about 90 nm can be formed by using, for example, an ArF excimer laser, but further fine pattern formation will be required in the future.

On the other hand, according to the immersion exposure, it is said that even when a light source having the same exposure wavelength is used, the same high resolution as that when a light source having a shorter wavelength is used can be achieved. Therefore, immersion exposure is attracting attention as a technique for achieving high resolution while reducing an increase in cost in the manufacture of semiconductor elements that require a large capital investment.

However, in immersion exposure, the resist film changes quality due to elution of substances contained in the resist into the immersion medium, etc., and its performance deteriorates, or the refractive index of the immersion medium changes locally due to the eluted substance. In addition, there may be a disadvantage that the lithographic properties are adversely affected due to contamination of the lens surface by the eluted substance (see WO 04/068242 pamphlet). For such inconvenience, it is conceivable to increase the hydrophobicity of the resist film. For this purpose, it is necessary to change the resist composition, and such a change usually tends to deteriorate the lithography characteristics. In addition, double exposure technology and double patterning technology are known as technologies for enhancing the resolution by using the characteristics of chemically amplified resist materials, but the technology for increasing the resolution without increasing the number of processes using existing equipment. For example, a technique using an organic solvent having a polarity lower than that of an alkaline aqueous solution as a developing solution is disclosed (see JP-A-2000-199953). It is difficult to form a fine pattern due to poor optical contrast when forming a trench pattern or a hole pattern using an alkaline aqueous solution as a developer, but when an organic solvent is used, This is because a fine pattern can be formed because the optical contrast can be increased.

In the formation of a resist pattern by immersion exposure as described above, particularly a trench pattern or a hole pattern, an optimal radiation-sensitive resin composition, a developer to be used, and a combination thereof have not been found to date.

International Publication No. 04/068242 Pamphlet JP 2000-199953 A

The present invention has been made based on the above circumstances, and an object thereof is to provide a method for forming a trench pattern or a hole pattern excellent in lithography characteristics, and a radiation-sensitive resin composition.

The invention made to solve the above problems is
(1) a resist film forming step of applying a radiation sensitive resin composition on a substrate;
(2) An exposure step of irradiating the resist film with radiation through a photomask, and (3) a trench pattern or hole pattern forming method including a development step of developing the exposed resist film,
The radiation sensitive resin composition is
[A] a polymer in which the content of the structural unit having an acid dissociable group is 10 mol% or less (hereinafter, also referred to as “[A] polymer”),
[B] a polymer in which the content of the structural unit having an acid dissociable group exceeds 10 mol% (hereinafter, also referred to as “[B] polymer”), and [C] a radiation-sensitive acid generator,
(3) A method for forming a trench pattern or a hole pattern, wherein the developer in the developing step contains 80% by mass or more of an organic solvent.

[A] The polymer has 10 mol% or less of a structural unit having an acid dissociable group, and even if all the acid dissociable groups are dissociated, the solubility of the [A] polymer in the developer is not impaired. Therefore, the occurrence of defects such as residues and bridges can be suppressed. Here, the structural unit having an acid dissociable group refers to a structural unit in which a hydrogen atom of a polar group such as a carboxy group is substituted with an acid dissociable group. On the other hand, the [B] polymer has a structural unit having an acid dissociable group in excess of 10 mol%, and this acid dissociable group is dissociated by the action of an acid generated from the [C] radiation sensitive acid generator. To do. As a result, the polarity increases, the poor solubility of the [B] polymer in the exposed area increases, and the dissolution of the polymer in the resist film in the unexposed area in the developing solution is promoted. Further, in the pattern forming method, a developer containing an organic solvent having a polarity lower than that of an alkaline aqueous solution used for forming a positive chemically amplified resist as a developer in the development step (dissolves an unexposed portion of the resist film, A developer capable of forming a negative image is used, and this organic solvent has excellent affinity with the resist film surface, and as a result, developability can be improved. Therefore, a combination of such a specific composition and a characteristic pattern forming method enables pattern formation excellent in lithography properties such as sensitivity, cross-sectional shape, hole pattern circularity, and resolution.

[A] The fluorine content of the polymer is preferably higher than that of the [B] polymer. [A] When the fluorine content of the polymer is higher than that of the [B] polymer, the [A] polymer tends to be unevenly distributed near the resist film surface, and the acid generator or [D It is possible to suppress the acid diffusion control agent and the like from being eluted into the immersion medium. Further, the advancing contact angle between the resist film and the immersion medium can be controlled within a desired range, and the occurrence of bubble defects can be suppressed. Furthermore, the receding contact angle between the resist film and the immersion medium is increased, and high-speed scanning exposure is possible without leaving water droplets.

The organic solvent contained in the developer is preferably at least one organic solvent selected from the group consisting of ether solvents, ketone solvents and ester solvents. By using the specific organic solvent, an appropriate combination with a predetermined resist composition can be realized, and a pattern with more excellent lithography characteristics can be obtained.

[A] The polymer comprises at least one structural unit selected from the group consisting of the structural unit (I) represented by the following formula (1) and the structural unit (II) represented by the following formula (2). It is preferable to have.

(In the formula (1), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ² is a linear or branched alkyl group having 1 to 6 carbon atoms or 4 carbon atoms. To 20 monovalent alicyclic hydrocarbon groups, provided that at least a part of the hydrogen atoms of the alkyl group and alicyclic hydrocarbon group are substituted with fluorine atoms.)

(In Formula (2), R ³ is a hydrogen atom, a methyl group or a trifluoromethyl group. R ⁴ is an (m + 1) -valent linking group. X is a divalent linking group having a fluorine atom. R ⁵ is a hydrogen atom or a monovalent organic group, m is an integer of 1 to 3, provided that when there are a plurality of m, the plurality of X and R ⁵ are the same as each other. May be different.)

[A] When the polymer has the above-mentioned specific structural unit, it has a fluorinated group in the structure, thereby improving the hydrophobicity of the resist film and being excellent in suppression of substance elution during immersion exposure. In addition, since the receding contact angle between the resist film and the immersion liquid can be sufficiently increased, and there are effects such as no water droplets remaining when scanning exposure is performed at high speed, it is highly useful for immersion exposure.

[B] The acid dissociable group of the polymer preferably has a chain hydrocarbon group or a monocyclic or polycyclic alicyclic hydrocarbon group. [B] Since the acid-dissociable group of the polymer has the above specific group, the resist film can be made highly transparent with respect to an ArF excimer laser or the like, and a pattern with higher resolution can be formed.

The radiation sensitive resin composition of the present invention,
(1) a resist film forming step of applying a radiation sensitive resin composition on a substrate;
(2) An exposure step of irradiating the resist film with radiation through a photomask, and (3) a trench pattern or hole pattern forming method including a development step of developing the exposed resist film,
The developer in the step (3) contains 80% by mass or more of an organic solvent,
The radiation sensitive resin composition is
[A] a polymer in which the content of the structural unit having an acid dissociable group is 10 mol% or less,
[B] A polymer in which the content of the structural unit having an acid dissociable group exceeds 10 mol%, and [C] a radiation-sensitive acid generator.

The present invention provides a method for forming a trench pattern or a hole pattern that is suitable for immersion exposure and has excellent lithography properties such as sensitivity, cross-sectional shape, circularity, and resolution, and a radiation-sensitive resin composition. Can do.

<Pattern formation method>
The pattern forming method of the present invention comprises:
(1) a resist film forming step of applying a radiation sensitive resin composition on a substrate;
(2) An exposure step of irradiating the resist film with radiation through a photomask, and (3) a development step of developing the exposed resist film. Hereinafter, each process is explained in full detail.

[Step (1)]
This step is a step of applying a radiation-sensitive resin composition of the present invention on a substrate to form a resist film. As the substrate, for example, a conventionally known substrate such as a silicon wafer or a wafer coated with aluminum can be used. An organic or inorganic antireflection film may be formed on the substrate.

Examples of the application method include spin coating, spin coating, roll coating, and the like. The thickness of the resist film to be formed is usually 0.01 μm to 1 μm, preferably 0.01 μm to 0.5 μm.

After applying the radiation sensitive resin composition, the solvent in the coating film may be volatilized by pre-baking (PB) as necessary. The heating conditions for PB are appropriately selected depending on the composition of the radiation sensitive resin composition, but are usually about 30 ° C. to 200 ° C., preferably 50 ° C. to 150 ° C.

In order to prevent the influence of basic impurities contained in the ambient atmosphere, a protective film disclosed in, for example, Japanese Patent Laid-Open No. 5-188598 can be provided on the resist layer. Further, in order to prevent the acid generator and the like from flowing out of the resist layer, an immersion protective film disclosed in, for example, Japanese Patent Application Laid-Open No. 2005-352384 can be provided on the resist layer. These techniques can be used in combination.

[Step (2)]
This step is a step of irradiating the resist film formed in step (1) with radiation through a photomask. Further, exposure is performed by reducing and projecting through an immersion liquid as necessary. For example, an isotrench pattern can be formed by performing reduced projection exposure on a desired region through an isoline pattern mask. Moreover, you may perform exposure twice or more with a desired pattern and a mask pattern. When performing exposure twice or more, it is preferable to perform exposure continuously. In the case of performing multiple exposures, for example, a first reduced projection exposure is performed on a desired area via a line and space pattern mask, and then the second is so that the line intersects the exposed portion where the first exposure has been performed. Reduced projection exposure is performed. The first exposure part and the second exposure part are preferably orthogonal. By being orthogonal, it becomes easy to form a circular contact hole pattern in the unexposed portion surrounded by the exposed portion. Examples of the immersion liquid used for exposure include water and a fluorine-based inert liquid. The immersion liquid is preferably a liquid that is transparent to the exposure wavelength and has a refractive index temperature coefficient that is as small as possible so as to minimize distortion of the optical image projected onto the film. In the case of excimer laser light (wavelength 193 nm), it is preferable to use water from the viewpoints of availability and easy handling in addition to the above-described viewpoints. When water is used, an additive that decreases the surface tension of water and increases the surface activity may be added in a small proportion. This additive is preferably one that does not dissolve the resist layer on the wafer and can ignore the influence on the optical coating on the lower surface of the lens. The water used is preferably distilled water.

The radiation used for exposure is appropriately selected according to the type of [C] radiation sensitive acid generator, and examples thereof include ultraviolet rays, far ultraviolet rays, X-rays, and charged particle beams. Among these, far ultraviolet rays represented by ArF excimer laser light and KrF excimer laser light (wavelength 248 nm) are preferable, and ArF excimer laser light is more preferable. The exposure conditions such as the exposure amount are appropriately selected according to the blending composition of the radiation-sensitive resin composition, the type of additive, and the like. In the pattern forming method of the present invention, the exposure process may be performed a plurality of times, and the plurality of exposures may be performed using the same light source or different light sources, but ArF excimer laser light is used for the first exposure. Is preferably used.

Moreover, it is preferable to perform post-exposure baking (PEB) after exposure. By performing PEB, the dissociation reaction of the acid dissociable group in the radiation sensitive resin composition can proceed smoothly. The heating conditions for PEB are usually 30 ° C. to 200 ° C., preferably 50 ° C. to 170 ° C.

[Step (3)]
This step is a step of developing the exposed resist film. Contains organic solvent after exposure. The developer used for development is not particularly limited as long as it selectively dissolves and removes the low-exposed portion and the unexposed portion, and contains 80% by mass or more of an organic solvent. Examples of the organic solvent include at least one selected from the group consisting of alcohol solvents, ether solvents, ketone organic solvents, amide solvents, ester organic solvents, and hydrocarbon solvents.

Examples of the alcohol solvent include 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 -Monoalcohol solvents such as heptadecyl alcohol, furfuryl alcohol, phenol, cyclohexanol, methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol, 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 ether solvents include diethyl ether, dipropyl ether, dibutyl ether, diphenyl ether, methoxybenzene, and the like.

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, methyl-n- And ketone solvents such as hexyl ketone, di-iso-butyl ketone, trimethylnonanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone, acetophenone, etc. .

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

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, 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, acetoacetic acid Methyl, 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.

Examples of hydrocarbon solvents include n-pentane, iso-pentane, n-hexane, iso-hexane, n-heptane, iso-heptane, 2,2,4-trimethylpentane, n-octane, iso-octane, cyclohexane , Aliphatic hydrocarbon solvents such as methylcyclohexane;
Fragrances such as benzene, toluene, xylene, mesitylene, ethylbenzene, trimethylbenzene, methylethylbenzene, n-propylbenzene, iso-propylbenzene, diethylbenzene, iso-butylbenzene, triethylbenzene, di-iso-propylbenzene, n-amylnaphthalene Group hydrocarbon solvents and the like.

Among these, the organic solvent is preferably at least one organic solvent selected from the group consisting of ether solvents, ketone solvents and ester solvents, and includes n-butyl acetate, isopropyl acetate, amyl acetate, Methyl ethyl ketone, methyl-n-butyl ketone, methyl-n-pentyl ketone, and anisole are more preferable. By using the specific organic solvent, an appropriate combination with a predetermined resist composition can be realized, and a pattern with more excellent lithography characteristics can be obtained. In addition, these organic solvents may be used independently and may use 2 or more types together.

An appropriate amount of a surfactant can be added to the developer as necessary. Examples of the surfactant include ionic and nonionic fluorine-based surfactants and silicon-based surfactants.

As a developing method, for example, a method in which a substrate is immersed in a tank filled with a developer for a certain period of time (dip method), a method in which the developer is raised on the surface of the substrate by surface tension and is left stationary for a certain time (paddle method) ), A method of spraying the developer on the substrate surface (spray method), a method of continuously applying the developer while scanning the developer coating nozzle on the substrate rotating at a constant speed (dynamic dispensing method) Etc.

In the pattern formation, it is preferable to wash the resist film with a rinsing liquid after the development in the step (3). Moreover, an organic solvent can be used also as the rinse liquid in the rinse process, and the generated scum can be efficiently washed. As the rinsing liquid, hydrocarbon solvents, ketone solvents, ester solvents, alcohol solvents, amide solvents and the like are preferable. Of these, alcohol solvents and ester solvents are preferable, and monovalent alcohol solvents having 6 to 8 carbon atoms are more preferable. Examples of monohydric alcohols having 6 to 8 carbon atoms include linear, branched or cyclic monohydric alcohols such as 1-hexanol, 1-heptanol, 1-octanol, and 4-methyl-2-pentanol. 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol, 3-heptanol, 3-octanol, 4-octanol, benzyl alcohol and the like. Of these, 1-hexanol, 2-hexanol, 2-heptanol, and 4-methyl-2-pentanol are preferable.

Each component of the rinse liquid may be used alone or in combination of two or more. The water content in the rinse liquid is preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 3% by mass or less. By setting the water content to 10% by mass or less, good development characteristics can be obtained. In addition, the surfactant mentioned later can be added to the rinse liquid.

As a cleaning method, for example, a method of continuously applying a rinse liquid onto a substrate rotating at a constant speed (rotary coating method), a method of immersing the substrate in a tank filled with the rinse liquid for a predetermined time (dip method) ), A method (spray method) of spraying a rinse liquid on the substrate surface, and the like.

<Radiation sensitive resin composition>
The radiation sensitive resin composition used in the present invention contains a [A] polymer, a [B] polymer, and a [C] radiation sensitive acid generator. [A] The polymer has 10 mol% or less of a structural unit having an acid dissociable group, and even if all the acid dissociable groups are dissociated, the solubility of the [A] polymer in the developer is not impaired. Therefore, the occurrence of defects such as residues and bridges can be suppressed. Here, the structural unit having an acid dissociable group refers to a structural unit in which a hydrogen atom of a polar group such as a carboxy group is substituted with an acid dissociable group. On the other hand, the [B] polymer has a structural unit having an acid dissociable group in excess of 10 mol%, and this acid dissociable group is dissociated by the action of an acid generated from the [C] radiation sensitive acid generator. To do. As a result, the polarity increases, the poor solubility of the [B] polymer in the exposed area increases, and the dissolution of the polymer in the resist film in the unexposed area in the developing solution is promoted. Moreover, the said radiation sensitive resin composition may contain arbitrary components, unless the effect of this invention is impaired. Hereinafter, each component will be described in detail.

<[A] polymer>
[A] A polymer is a polymer whose content rate of the structural unit which has an acid dissociable group is 10 mol% or less. Since the content ratio of the structural unit having an acid-dissociable group is 10 mol% or less, even if all the acid-dissociable groups are dissociated, the solubility in the developer is not impaired. Can be suppressed. Examples of the structural unit having an acid dissociable group include a structural unit (III) represented by the formula (5) described later. [A] As a content rate of the structural unit which has an acid dissociable group in a polymer, 0 mol% is preferable.

Further, the fluorine content of the [A] polymer is preferably higher than that of the [B] polymer. [A] When the fluorine content of the polymer is higher than that of the [B] polymer, the [A] polymer tends to be unevenly distributed near the resist film surface, and the acid generator or [D It is possible to suppress the acid diffusion control agent and the like from being eluted into the immersion medium. Further, the advancing contact angle between the resist film and the immersion medium can be controlled within a desired range, and the occurrence of bubble defects can be suppressed. Furthermore, the receding contact angle between the resist film and the immersion medium is increased, and high-speed scanning exposure is possible without leaving water droplets.

Examples of the [A] polymer containing a fluorine atom include (i) a structure in which a fluorinated alkyl group is bonded to the main chain, (ii) a structure in which a fluorinated alkyl group is bonded to a side chain, (iii) Examples include a structure in which a fluorinated alkyl group is bonded to a chain and a side chain.

Examples of the monomer that gives the polymer having the structure (i) include an α-trifluoromethyl acrylate compound, a β-trifluoromethyl acrylate compound, an α, β-trifluoromethyl acrylate compound, and one or more types of vinyl moieties. And the like in which hydrogen is substituted with a fluorinated alkyl group such as a trifluoromethyl group.

Examples of the monomer that gives a polymer having the structure (ii) include those in which the side chain of an alicyclic olefin compound such as norbornene is a fluorinated alkyl group, a fluorinated alkyl ester compound of acrylic acid or methacrylic acid, One or more olefin side chains (sites not containing a double bond) are fluorinated alkyl groups or derivatives thereof.

Examples of the monomer that gives a polymer having the structure (iii) include fluorinated side chains such as α-trifluoromethylacrylic acid, β-trifluoromethylacrylic acid, α, β-trifluoromethylacrylic acid, etc. An ester compound of an alkyl group or a derivative thereof, a compound in which the side chain of a compound in which hydrogen at one or more vinyl sites is substituted with a fluorinated alkyl group such as a trifluoromethyl group, or the like is substituted with a fluorinated alkyl group or a derivative thereof; Examples include those in which hydrogen bonded to the double bond of more than one kind of alicyclic olefin compound is substituted with a fluorinated alkyl group such as a trifluoromethyl group and the side chain is a fluorinated alkyl group or a derivative thereof. It is done. In addition, an alicyclic olefin compound shows the compound in which a part of ring is a double bond.

[A] The polymer comprises at least one structural unit selected from the group consisting of the structural unit (I) represented by the formula (1) and the structural unit (II) represented by the formula (2). It is preferable to have. [A] The polymer may have “another structural unit” other than the structural unit (I) and the structural unit (II). [A] A polymer may have 2 or more types of each structural unit. Hereinafter, each structural unit will be described in detail.

[Structural unit (I)]
The structural unit (I) is a structural unit represented by the above formula (1). In said formula (1), R < ¹ > is a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group. R ² is a linear or branched alkyl group having 1 to 6 carbon atoms or a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms. However, at least a part of the hydrogen atoms of the alkyl group and the alicyclic hydrocarbon group are substituted with fluorine atoms.

Examples of the linear or branched alkyl group having 1 to 6 carbon atoms represented by R ² include a methyl group, an ethyl group, an n-propyl group, and an n-butyl group.

Examples of the monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms represented by R ² include a cyclopentyl group, a cyclopentylpropyl group, a cyclohexyl group, a cyclohexylmethyl group, a cycloheptyl group, a cyclooctyl group, and a cyclooctyl group. A methyl group etc. are mentioned.

As the structural unit (I), structural units represented by the following formulas (1-1) and (1-2) are preferable.

In the above formulas (1-1) and (1-2), R ¹ has the same meaning as in the above formula (1).

Examples of the monomer that gives the structural unit (I) include trifluoromethyl (meth) acrylate, 2,2,2-trifluoroethyl (meth) acrylate, perfluoroethyl (meth) acrylate, perfluoro n-propyl ( (Meth) acrylate, perfluoro i-propyl (meth) acrylate, perfluoro n-butyl (meth) acrylate, perfluoro i-butyl (meth) acrylate, perfluoro t-butyl (meth) acrylate, perfluorocyclohexyl (meth) Acrylate, 2- (1,1,1,3,3,3-hexafluoro) propyl (meth) acrylate, 1- (2,2,3,3,4,4,5,5-octafluoro) pentyl ( (Meth) acrylate, 1- (2,2,3,3,4,4,5,5-octafluoro) hex (Meth) acrylate, perfluorocyclohexylmethyl (meth) acrylate, 1- (2,2,3,3,3-pentafluoro) propyl (meth) acrylate, 1- (2,2,3,3,4, 4,4-Heptafluoro) penta (meth) acrylate, 1- (3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10- Heptadecafluoro) decyl (meth) acrylate, 1- (5-trifluoromethyl-3,3,4,4,5,6,6,6-octafluoro) hexyl (meth) acrylate and the like.

[A] The content of the structural unit (I) in the polymer is preferably 30 mol% to 100 mol% with respect to the total structural units.

[Structural unit (II)]
The structural unit (II) is a structural unit represented by the above formula (2). In the above formula (2), R ³ is a hydrogen atom, a methyl group or a trifluoromethyl group. R ⁴ is a (m + 1) -valent linking group. X is a divalent linking group having a fluorine atom. R ⁵ is a hydrogen atom or a monovalent organic group. m is an integer of 1 to 3. However, when m is plural, the plural X and R ⁵ may be the same or different.

Examples of the (m + 1) -valent linking group represented by R ⁴ include a linear or branched hydrocarbon group having 1 to 30 carbon atoms, an alicyclic hydrocarbon group having 3 to 30 carbon atoms, and a carbon number. 6-30 aromatic hydrocarbon groups, or these groups combined with one or more groups selected from the group consisting of oxygen atom, sulfur atom, ether group, ester group, carbonyl group, imino group and amide group Groups and the like. The (m + 1) -valent linking group may have a substituent.

Examples of the linear or branched hydrocarbon group having 1 to 30 carbon atoms include hydrocarbon groups such as methane, ethane, propane, butane, pentane, hexane, heptane, decane, icosane and triacontane (m + 1). And a group excluding individual hydrogen atoms.

Examples of the alicyclic hydrocarbon group having 3 to 30 carbon atoms include monocyclic saturated hydrocarbons such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclodecane, methylcyclohexane, and ethylcyclohexane;
Monocyclic unsaturated hydrocarbons such as cyclobutene, cyclopentene, cyclohexene, cycloheptene, cyclooctene, cyclodecene, cyclopentadiene, cyclohexadiene, cyclooctadiene, cyclodecadiene;
Bicyclo [2.2.1] heptane, bicyclo [2.2.2] octane, tricyclo [5.2.1.0 ^2,6 ] decane, tricyclo [3.3.1.1 ^3,7 ] decane, Tetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] polycyclic saturated hydrocarbons such as dodecane and adamantane;
Bicyclo [2.2.1] heptene, bicyclo [2.2.2] octene, tricyclo [5.2.1.0 ^2,6 ] decene, tricyclo [3.3.1.1 ^3,7 ] decene, Tetracyclo [6.2.1.1 ^3,6 . And a group obtained by removing (m + 1) hydrogen atoms from a polycyclic hydrocarbon group such as 0 ^2,7 ] dodecene.

Examples of the aromatic hydrocarbon group having 6 to 30 carbon atoms include (m + 1) from aromatic hydrocarbon groups such as benzene, naphthalene, phenanthrene, anthracene, tetracene, pentacene, pyrene, picene, toluene, xylene, ethylbenzene, mesitylene, cumene and the like. ) Groups from which a single hydrogen atom is removed.

Examples of the substituent that the (m + 1) -valent linking group may have include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a 2-methylpropyl group, 1- Examples thereof include alkyl groups such as methylpropyl group, t-butyl group and cyclohexyl group, hydroxy group, cyano group, hydroxyalkyl group having 1 to 10 carbon atoms, carboxy group, carbonyl group and the like.

Examples of the divalent linking group having a fluorine atom represented by X include a C 1-20 divalent linear hydrocarbon group having a fluorine atom. Examples of the divalent linear hydrocarbon group having 1 to 20 carbon atoms having a fluorine atom include groups represented by the following formulas (X-1) to (X-6).

X is preferably a group represented by the above formula (X-1) or (X-2).

Examples of the monovalent organic group represented by R ⁵ include linear or branched hydrocarbon groups having 1 to 30 carbon atoms, alicyclic hydrocarbon groups having 3 to 30 carbon atoms, and 6 to 6 carbon atoms. 30 aromatic hydrocarbon groups, or a combination of these groups and one or more groups selected from the group consisting of oxygen, sulfur, ether, ester, carbonyl, imino and amide groups, etc. Is mentioned.

The group represented by R ⁵ is preferably a hydrogen atom from the viewpoint of improving the solubility of the [A] polymer in the developer.

Examples of the structural unit (II) include structural units represented by the following formulas (2-1) and (2-2).

In the above formula (2-1), R ⁴ is a divalent linear, branched or cyclic saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms. R ³ , X and R ⁵ are as defined in the above formula (2). In the above formula (2-2), R ³ , X, R ⁵ and m are as defined in the above formula (2). However, when m is plural, the plural X and R ⁵ may be the same or different.

The structural unit (II) is preferably a structural unit represented by the following formula.

In said formula, R < ³ > is synonymous with the said Formula (2).

Examples of the monomer that gives structural unit (II) include (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-3-propyl) ester, (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-butyl) ester, (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy -5-pentyl) ester, (meth) acrylic acid (1,1,1-trifluoro-2-trifluoromethyl-2-hydroxy-4-pentyl) ester, (meth) acrylic acid 2-{[5- ( 1 ′, 1 ′, 1′-trifluoro-2′-trifluoromethyl-2′-hydroxy) propyl] bicyclo [2.2.1] heptyl} ester and the like.

[A] The content ratio of the structural unit (II) in the polymer is preferably 30 mol% to 100 mol% with respect to the total structural units.

[Other structural units]
[A] The polymer is further divided into “other structural units” as a structural unit having a lactone structure to control the dissolution rate in the developer, a structural unit having a cyclic carbonate structure, and an alicyclic ring to increase etching resistance. You may have a structural unit etc. which have a formula structure.

Examples of the structural unit having a lactone structure and the structural unit having a cyclic carbonate structure include a structural unit represented by the following formula. Here, the group having a lactone structure refers to a cyclic group containing one ring (lactone ring) containing an —O—C (O) — structure. The lactone ring is counted as the first ring, and when it is only the lactone ring, it is called a monocyclic group, and when it has another ring structure, it is called a polycyclic group regardless of the structure.

In the above formula, R ^L1 is a hydrogen atom, a methyl group or a trifluoromethyl group.

Examples of the monomer that gives a structural unit having a lactone structure include a compound represented by the following formula (L-1). As the monomer that gives the structural unit having a lactone structure, monomers described in International Publication No. 2007/116664 pamphlet are preferable.

Examples of the structural unit having an alicyclic structure include a structural unit represented by the following formula (4).

In the formula (4), R ⁶ is a hydrogen atom, a methyl group or a trifluoromethyl group. X ² is an alicyclic hydrocarbon group having 4 to 20 carbon atoms.

Examples of the alicyclic hydrocarbon group having 4 to 20 carbon atoms include cyclobutane, cyclopentane, cyclohexane, bicyclo [2.2.1] heptane, bicyclo [2.2.2] octane, and tricyclo [5.2.1]. .0 ^2,6] decane, tetracyclo [6.2.1.1 ^3,6. 0 ^2,7 ] dodecane, tricyclo [3.3.1.1 ^3,7 ] decane and the like. These alicyclic hydrocarbon groups having 4 to 20 carbon atoms may have a substituent. Examples of the substituent include those having 1 to 4 carbon atoms such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, 2-methylpropyl group, 1-methylpropyl group and t-butyl group. Examples thereof include a linear, branched or cyclic alkyl group, a hydroxyl group, a cyano group, a hydroxyalkyl group having 1 to 10 carbon atoms, a carboxy group, and an oxygen atom.

Examples of the monomer that gives a structural unit containing an alicyclic compound include (meth) acrylic acid-bicyclo [2.2.1] hept-2-yl ester and (meth) acrylic acid-bicyclo [2.2. 2] Oct-2-yl ester, (meth) acrylic acid-tricyclo [5.2.1.0 ^2,6 ] dec-7-yl ester, (meth) acrylic acid-tricyclo [3.3.1.1] ^3,7 ] dec-1-yl ester, (meth) acrylic acid-tricyclo [3.3.1.1 ^3,7 ] dec-2-yl ester, and the like.

In addition, it is preferable that the [A] polymer does not have a structural unit having an aromatic group. In particular, when an ArF light source is used, it may cause a decrease in sensitivity.

<[A] Polymer Synthesis Method>
[A] The polymer can be produced, for example, by polymerizing a monomer corresponding to each predetermined structural unit in a suitable solvent using a radical polymerization initiator.

Examples of the solvent used for the polymerization include alkanes such as n-pentane, n-hexane, n-heptane, n-octane, n-nonane and n-decane;
Cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, norbornane;
Aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, cumene;
Halogenated hydrocarbons such as chlorobutanes, bromohexanes, dichloroethanes, hexamethylene dibromide, chlorobenzene;
Saturated carboxylic acid esters such as ethyl acetate, n-butyl acetate, i-butyl acetate and methyl propionate;
Ketones such as acetone, 2-butanone, 4-methyl-2-pentanone, 2-heptanone;
Ethers such as tetrahydrofuran, dimethoxyethanes, diethoxyethanes;
Examples thereof include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, and 4-methyl-2-pentanol. These solvents may be used alone or in combination of two or more.

The reaction temperature in the above polymerization is usually preferably 40 ° C to 150 ° C and 50 ° C to 120 ° C. The reaction time is usually preferably 1 hour to 48 hours and 1 hour to 24 hours.

[A] The weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) of the polymer is preferably 1,000 to 50,000, more preferably 1,000 to 30,000, and 1,000. ˜10,000 is particularly preferred. [A] When the Mw of the polymer is less than 1,000, a sufficient advancing contact angle cannot be obtained. On the other hand, when Mw exceeds 50,000, the developability of the resist tends to decrease.

[A] The ratio (Mw / Mn) of the polymer Mw to the polystyrene-equivalent number average molecular weight (Mn) by GPC method is usually 1 to 3, preferably 1 to 2. In addition, Mw and Mn in this specification were measured on the following conditions using the GPC column (Tosoh Corp., 2 G2000HXL, 1 G3000HXL, 1 G4000HXL).
Column temperature: 40 ° C
Elution solvent: Tetrahydrofuran (Wako Pure Chemical Industries)
Flow rate: 1.0 mL / min Sample concentration: 1.0 mass%
Sample injection volume: 100 μL
Detector: Differential refractometer Standard material: Monodisperse polystyrene

<[B] polymer>
[B] The polymer is a polymer containing more than 10 mol% of a structural unit having an acid dissociable group. In addition, the [B] polymer is a polymer whose polarity is increased by the action of an acid and hardly or insoluble in a developer containing an organic solvent.

[Structural unit (III)]
Examples of the structural unit having an acid dissociable group include structural unit (III) represented by the following formula (5).

In the above formula (5), R ⁷ is a hydrogen atom, a methyl group or a trifluoromethyl group. R ^p is an acid dissociable group.

The acid dissociable group represented by R ^p is preferably a group represented by the following formula (6).

In the above formula (6), R ^p1 is an alkyl group having 1 to 4 carbon atoms or a monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms. R ^p2 and R ^p3 are each independently an alkyl group having 1 to 4 carbon atoms or an alicyclic hydrocarbon group having 4 to 20 carbon atoms. R ^p2 and R ^p3 may be bonded to each other to form a divalent alicyclic hydrocarbon group having 4 to 20 carbon atoms together with the carbon atoms to which R ^p2 and R ^p3 are bonded. However, some or all of the hydrogen atoms of these groups may be substituted with a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms.

Examples of the alkyl group having 1 to 4 carbon atoms represented by R ^p1 , R ^p2 and R ^p3 include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, and 2-methylpropyl. Group, 1-methylpropyl group, t-butyl group and the like.

Examples of the monovalent alicyclic hydrocarbon group having 4 to 20 carbon atoms represented by R ^p1 , R ^p2 and R ^p3 include polycyclic alicyclic rings having a bridged skeleton such as an adamantane skeleton and a norbornane skeleton. A formula group;
And monocyclic alicyclic groups having a cycloalkane skeleton such as cyclopentane and cyclohexane.

As the acid dissociable group represented by R ^p , R ^p1 is an alkyl group having 1 to 4 carbon atoms, R ^p2 and R ^p3 are bonded to each other, and together with the carbon atom to which each is bonded, an adamantane skeleton or It is preferable to form a divalent group having a cycloalkane skeleton.

Examples of the structural unit (III) include a structural unit represented by the following formula.

In said formula, R < ⁷ > is synonymous with the said Formula (5).

[B] The content of the structural unit (III) in the polymer is preferably 20 mol% to 60 mol% with respect to the total structural units. In addition, the [B] polymer may have 1 type, or 2 or more types of structural units (III).

[Structural unit (IV)]
[B] The polymer preferably has a structural unit (IV) that does not have a fluorine atom and is derived from an acrylate ester having a lactone structure. [B] Since the polymer has the structural unit (IV), the adhesion of the resist film to the substrate can be improved. As the structural unit (IV), a structural unit similar to the structural unit having a lactone structure as the “other structural unit” described above and having no fluorine atom can be applied.

[B] The content ratio of the structural unit (IV) in the polymer is preferably 30 mol% to 60 mol% with respect to the total structural units.

[Other structural units]
[B] The polymer may have other structural units different from the structural unit (III) and the structural unit (IV). Examples of the other structural unit include a structural unit represented by the following formula containing a polar group.

In the above formula, R ⁸ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group.

[B] The content of the structural unit (V) in the polymer is preferably 0 mol% to 30 mol%, more preferably 0 mol% to 20 mol%.

<[B] Polymer Synthesis Method>
[B] The polymer can be produced, for example, by polymerizing a monomer corresponding to each predetermined structural unit in a suitable solvent using a radical polymerization initiator.

Examples of the solvent used for the polymerization include the same solvents as mentioned in the method for synthesizing [A] polymer. The reaction temperature in the polymerization is usually preferably 40 ° C. to 150 ° C. and 50 ° C. to 120 ° C. The reaction time is usually preferably 1 hour to 48 hours and 1 hour to 24 hours.

[B] The Mw of the polymer by GPC method is preferably 1,000 to 100,000, more preferably 1,000 to 50,000, and particularly preferably 1,000 to 30,000. [B] By setting the Mw of the polymer in the above specific range, the polymer has sufficient solubility in a resist solvent to be used as a resist, and the dry etching resistance and resist pattern cross-sectional shape are improved. [B] The ratio of Mw to Mn (Mw / Mn) of the polymer is usually 1 to 3, and preferably 1 to 2.

<[C] Radiation sensitive acid generator>
[C] The radiation sensitive acid generator generates an acid upon exposure, and the acid dissociates an acid dissociable group present in the [B] polymer to generate an acid. As the containing form of the [C] radiation sensitive acid generator in the radiation sensitive resin composition, even in the form of a compound as described later (hereinafter also referred to as “[C] radiation sensitive acid generator” as appropriate) [B] The form may be contained as a structural unit of a polymer or other polymer, or may be a form in which both are combined.

[C] Examples of the radiation sensitive acid generator include onium salt compounds, sulfonimide compounds, halogen-containing compounds, diazoketone compounds and the like. Of these [C] radiation sensitive acid generators, 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.

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-cyclohexyl Phenyldiphenylsulfonium perfluoro-n-octanesulfonate, 4-cyclohexylphenyl diphe 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, trif Niruhosuhoniumu 1,1,2,2-tetrafluoro-6- (1-adamantanecarbonyloxy) - hexane-1-sulfonate, and the like. Of these, triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate and triphenylphosphonium 1,1,2,2-tetrafluoro-6- (1-adamantane carbonyloxy) -hexane-1 Sulfonate is preferred.

Examples of the tetrahydrothiophenium salt include 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium nona. Fluoro-n-butanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium perfluoro-n-octanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiofe Nitro 2-bicyclo [2.2.1] hept-2-yl-1,1,2,2-tetrafluoroethanesulfonate, 1- (4-n-butoxynaphthalen-1-yl) tetrahydrothiophenium camphorsulfonate , 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-tert-butylphenyl) iodonium trifluoromethanesulfonate, bis (4-tert-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.

These [C] radiation sensitive acid generators may be used alone or in combination of two or more. [C] The amount used when the radiation-sensitive acid generator is an acid generator is usually 0 with respect to 100 parts by mass of the polymer [B] from the viewpoint of ensuring sensitivity and developability as a resist. .1 to 20 parts by mass, preferably 0.5 to 15 parts by mass. [C] If the usage-amount of a radiation sensitive acid generator is less than 0.1 mass part, there exists a tendency for a sensitivity and developability to fall. On the other hand, when the amount of the [C] radiation sensitive acid generator used exceeds 15 parts by mass, the transparency to radiation tends to decrease, and it becomes difficult to obtain a desired resist pattern.

<Optional component>
In addition to the [A] polymer, [B] polymer and [C] radiation sensitive acid generator, the radiation sensitive resin composition includes [D] acid diffusion as an optional component within a range not impairing the effects of the present invention. A control body, [E] solvent, surfactant, alicyclic skeleton containing compound, sensitizer and the like can be contained. Hereinafter, each optional component will be described in detail.

[[D] Acid diffusion controller]
[D] The acid diffusion controller controls the diffusion phenomenon in the resist coating film of the acid generated from the [C] radiation-sensitive acid generator by exposure, and has the effect of suppressing undesirable chemical reactions in non-exposed areas, The storage stability of the resulting radiation-sensitive resin composition is further improved, the resolution as a resist is further improved, and it is possible to suppress changes in the line width of the resist pattern due to fluctuations in the holding time from exposure to development processing. And a composition having excellent process stability can be obtained. [D] The inclusion form of the acid diffusion controller in the radiation-sensitive resin composition may be a form of a free compound, a form contained as a structural unit of a polymer, or a combination of both.

[D] Examples of the acid diffusion controller include amine compounds, amide group-containing compounds, urea compounds, nitrogen-containing heterocyclic compounds, and the like.

Examples of the amine compound include mono (cyclo) alkylamines; di (cyclo) alkylamines; tri (cyclo) alkylamines; substituted alkylanilines or derivatives thereof; ethylenediamine, N, N, N ′, N′-tetra Methylethylenediamine, tetramethylenediamine, hexamethylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 4,4′-diaminobenzophenone, 4,4′-diaminodiphenylamine, 2,2-bis (4 -Aminophenyl) propane, 2- (3-aminophenyl) -2- (4-aminophenyl) propane, 2- (4-aminophenyl) -2- (3-hydroxyphenyl) propane, 2- (4-amino) Phenyl) -2- (4-hydroxyphenyl) propane, 1 4-bis (1- (4-aminophenyl) -1-methylethyl) benzene, 1,3-bis (1- (4-aminophenyl) -1-methylethyl) benzene, bis (2-dimethylaminoethyl) Ether, bis (2-diethylaminoethyl) ether, 1- (2-hydroxyethyl) -2-imidazolidinone, 2-quinoxalinol, N, N, N ′, N′-tetrakis (2-hydroxypropyl) ethylenediamine N, N, N ′, N ″ N ″ -pentamethyldiethylenetriamine and the like.

Examples of amide group-containing compounds include Nt-butoxycarbonyl group-containing amino compounds, formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, propionamide, Examples thereof include benzamide, pyrrolidone, N-methylpyrrolidone, N-acetyl-1-adamantylamine, and isocyanuric acid tris (2-hydroxyethyl).

Examples of urea compounds include urea, methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3,3-tetramethylurea, 1,3-diphenylurea, tri-n-butylthiourea, etc. Is mentioned.

Examples of the nitrogen-containing heterocyclic compound include imidazoles; pyridines; piperazines; pyrazine, pyrazole, pyridazine, quinosaline, purine, pyrrolidine, piperidine, piperidine ethanol, 3-piperidino-1,2-propanediol, morpholine, 4- Methylmorpholine, 1- (4-morpholinyl) ethanol, 4-acetylmorpholine, 3- (N-morpholino) -1,2-propanediol, 1,4-dimethylpiperazine, 1,4-diazabicyclo [2.2.2 ] Octane etc. are mentioned.

Further, as the [D] acid diffusion control agent, a photodegradable base that is exposed to light and generates a weak acid can be used. The photodegradable base generates an acid in the exposed portion to increase the insolubility of the [B] polymer in the developer, while the unexposed portion exhibits a high acid capturing function by an anion and functions as a quencher. Captures acid that diffuses from As an example of the photodegradable base, there is an onium salt compound that is decomposed by exposure and loses acid diffusion controllability. Examples of the onium salt compound include a sulfonium salt compound represented by the following formula (7), an iodonium salt compound represented by the following formula (8), and the like.

The equation (7) and wherein ^{(8), R 18 ~ R} 22 are each independently a hydrogen atom, an alkyl group, an alkoxy group, hydroxy group, a halogen atom, or _-SO 2 -R ^C. R ^C is an alkyl group, a cycloalkyl group, an alkoxy group or an aryl group. In the above formulas (7) and (8), Z ⁻ represents OH ⁻ , R ²³ —COO ⁻ , R ^D —SO ₂ —N ⁻ —R ²³ , R ²³ —SO ₃ ⁻ , or the following formula (9) An anion represented by R ²³ is a linear or branched alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, or an alkaryl group having 7 to 30 carbon atoms. . However, one part or all part of the hydrogen atom which the said alkyl group, cycloalkyl group, aryl group, and alkaryl group have may be substituted. R ^D is a linear or branched alkyl group having 1 to 10 carbon atoms or a cycloalkyl group having 3 to 20 carbon atoms. However, some or all of the hydrogen atoms of the alkyl group and cycloalkyl group may be substituted with fluorine atoms. However, when Z ⁻ is R ²³ —SO ₃ ^— , the fluorine atom is not bonded to the carbon atom to which SO ₃ ^— is bonded.

In the above formula (9), R ²⁴ represents a linear or branched alkyl group having 1 to 12 carbon atoms, in which part or all of the hydrogen atoms may be substituted with fluorine atoms, or 1 to 12 carbon atoms. These are linear or branched alkoxyl groups. u is an integer of 0-2.

The alkyl group represented by R ^23, a methyl group, an ethyl group, a propyl group, i- propyl group, butyl group, i- butyl group, a t- butyl group and the like can be mentioned.

The cycloalkyl group represented by R ^23, for example a cyclopentyl group, a cyclohexyl group, a norbornyl group, tricyclodecanyl group, tetracyclododecanyl group, and adamantyl.

The aryl group represented by R ^23, a phenyl group, a naphthyl group, anthranyl group, and the like.

The alkaryl group represented by R ^23, for example, benzyl, phenylethyl group, phenylpropyl group and the like.

Examples of the substituent that the alkyl group, cycloalkyl group, aryl group, and alkaryl group have include a hydroxyl group, a halogen atom, an alkoxy group, a lactone group, and an alkylcarbonyl group.

Examples of the alkyl group represented by ^RD include a methyl group, an ethyl group, a propyl group, and a butyl group.

Examples of the cycloalkyl group represented by ^RD include a cyclopentyl group, a cyclohexyl group, a norbornyl group, an adamantyl group, and the like.

Examples of the photodegradable base include compounds represented by the following formulas.

[D] The acid diffusion controller may be used alone or in combination of two or more. [D] The content of the acid diffusion controller is preferably less than 15 parts by mass with respect to 100 parts by mass of the [B] polymer. When the content exceeds 15 parts by mass, the sensitivity as a resist tends to decrease.

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

Specific examples of the solvent include the same organic solvents listed in the pattern formation step (3) above. Of these, propylene glycol monomethyl ether acetate and cyclohexanone are preferred. These solvents may 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 diacrylate. In addition to nonionic surfactants such as stearate, the following trade names are KP341 (Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 (above, Kyoeisha Chemical Co., Ltd.), F-Top EF301, EF303, EF352 (above, Tochem Products), MegaFuck F171, F173 (above, Dainippon Ink and Chemicals), Florard FC430, FC431 ( Sumitomo 3M), Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105, SC-106 (above, Asahi Glass Industry) Company). These surfactants may 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.

[Sensitizer]
The sensitizer exhibits an action of increasing the amount of [C] radiation-sensitive acid generator, and has an effect of improving the “apparent sensitivity” of the radiation-sensitive resin composition.

<Preparation of radiation-sensitive resin composition>
The radiation-sensitive resin composition can be prepared, for example, by mixing [A] polymer, [B] polymer, [C] radiation-sensitive acid generator, and optional components in a predetermined ratio in an organic solvent. . Moreover, the said radiation sensitive resin composition can be prepared and used in the state melt | dissolved or disperse | distributed to the appropriate organic solvent. [A] The content of the polymer is preferably 1 part by mass to 15 parts by mass and more preferably 2 parts by mass to 10 parts by mass with respect to 100 parts by mass of the polymer [B].

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples.

<[A] Synthesis of polymer>
[Synthesis Example 1]
10.4 g (30 mol%) of a monomer represented by the following formula (M-1) and 19.6 g (70 mol%) of a monomer represented by the formula (M-4) were dissolved in 30 g of methyl ethyl ketone, Further, a solution charged with 0.91 g of 2,2′-azobis (isobutyronitrile) was prepared. Next, a 200 mL three-necked flask charged with 30 g of methyl ethyl ketone was purged with nitrogen for 30 minutes, and then the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added over 3 hours using a dropping funnel. And dripped. 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 solution was cooled with water and cooled to 30 ° C. or lower. The reaction solution was transferred to a 1 L separatory funnel, and then the polymerization solution was uniformly diluted with 90 g of n-hexane, and 360 g of methanol was added. Mixed. Next, 20 g of distilled water was added, and the mixture was further stirred and allowed to stand for 30 minutes. Thereafter, the lower layer was recovered to obtain a propylene glycol monomethyl ether solution containing the polymer (A-1). Mw of the polymer (A-1) was 5,900, Mw / Mn was 1.58, and the yield was 68%. As a result of ¹³ C-NMR analysis, the content ratio of the structural unit (II) given by (M-1) and the structural unit (I) given by (M-4) was 31:69 (mol%). The ¹³ C-NMR analysis was measured using a nuclear magnetic resonance apparatus (JEOL Ltd., JNM-EX270).

[Synthesis Examples 2 to 10]
Each polymer was synthesized in the same manner as in Synthesis Example 1 except that a predetermined amount of the monomers listed in Table 1 were blended. In addition, Table 1 shows the Mw, Mw / Mn, yield (%), and the content ratio of the structural unit provided by each monomer in each polymer. In addition, the monomer used for the synthesis | combination of each [A] polymer is shown below.

<[B] Synthesis of polymer>
[B] Monomers used for polymer synthesis are shown below.

[Synthesis Example 11]
12.9 g (50 mol%) of the monomer represented by the above formula (M-11) and 17.1 g (50 mol%) of the monomer represented by the formula (M-16) were dissolved in 60 g of methyl ethyl ketone, Further, a solution charged with 1.77 g of dimethylazobisisobutyronitrile was prepared. Next, a 200 mL three-necked flask charged with 30 g of methyl ethyl ketone was purged with nitrogen for 30 minutes, and then the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added over 3 hours using a dropping funnel. And dripped. 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 with water, cooled to 30 ° C. or lower, poured into 600 g of methanol, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 150 g of methanol in the form of a slurry, then filtered again and dried at 50 ° C. for 17 hours to obtain a white powder (B-1) polymer. Mw of the polymer (B-1) was 6,900, Mw / Mn was 1.35, and the yield was 80%. As a result of ¹³ C-NMR analysis, the content ratio of the structural unit (III) given by (M-11) and the structural unit (IV) given by (M-16) was 49:51 (mol%).

[Synthesis Example 12]
In the above formula (M-12), 12.57 g (35 mol%) of the monomer represented by the formula (M-12), 5.13 g (15 mol%) of the monomer represented by the formula (M-15), and formula (M-17) A solution was prepared by dissolving 12.30 g (50 mol%) of the monomer represented in 60 g of methyl ethyl ketone and further adding 1.19 g of dimethylazobisisobutyronitrile. Next, a 200 mL three-necked flask charged with 30 g of methyl ethyl ketone was purged with nitrogen for 30 minutes, and then the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added over 3 hours using a dropping funnel. And dripped. 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 with water, cooled to 30 ° C. or lower, poured into 600 g of methanol, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 150 g of methanol in the form of a slurry, then filtered again and dried at 50 ° C. for 17 hours to obtain a white powder (B-2) polymer. Mw of the polymer (B-2) was 5,800, Mw / Mn was 1.37, and the yield was 68%. As a result of ¹³ C-NMR analysis, the content ratio of the structural unit (III) given by (M-12), the structural unit given by (M-15), and the structural unit (IV) given by (M-17) was 33: 16:51 (mol%).

[Synthesis Example 13]
11.73 g (40 mol%) of the monomer represented by the above formula (M-13), 2.62 g (10 mol%) of the monomer represented by the formula (M-14), and (M-18) A solution was prepared by dissolving 15.66 g (50 mol%) of the monomer represented in 60 g of methyl ethyl ketone and further adding 0.92 g of dimethylazobisisobutyronitrile. Next, a 200 mL three-necked flask charged with 30 g of methyl ethyl ketone was purged with nitrogen for 30 minutes, and then the reaction kettle was heated to 80 ° C. with stirring, and the monomer solution prepared in advance was added over 3 hours using a dropping funnel. And dripped. 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 with water, cooled to 30 ° C. or lower, poured into 600 g of methanol, and the precipitated white powder was separated by filtration. The filtered white powder was washed twice with 150 g of methanol in the form of a slurry, then filtered again and dried at 50 ° C. for 17 hours to obtain a white powder (B-3) polymer. Mw of the polymer (B-3) was 7,200, Mw / Mn was 1.41, and the yield was 75%. As a result of ¹³ C-NMR analysis, the content ratio of the structural unit (III) given by (M-13), the structural unit given by (M-14), and the structural unit (IV) given by (M-18) was 40: It was 10:50 (mol%).

<Preparation of radiation-sensitive resin composition>
The [C] radiation sensitive acid generator, acid diffusion controller and solvent used in the preparation of the radiation sensitive resin composition are as follows.

<[C] Radiation sensitive acid generator>
Compound represented by the following formula

<[D] Acid diffusion controller>
Compound represented by the following formula

<[E] solvent>
E-1: Propylene glycol monomethyl ether acetate E-2: Cyclohexanone E-3: γ-butyrolactone

[Example 1]
[A] 3 parts by mass of (A-1) as a polymer, [B] 100 parts by mass of (B-1) as a polymer, [C] (C-1) as a radiation-sensitive acid generator 8 parts by mass, (D) 4.3 parts by mass as an acid diffusion controller, (E-1) 2,185 parts by mass as an [E] solvent, (E-2) 935 parts by mass, (E-3) A radiation-sensitive resin composition was prepared by mixing 30 parts by mass.

[Examples 2 to 13 and Comparative Examples 1 and 2]
Each radiation-sensitive resin composition was prepared in the same manner as in Example 1 except that a predetermined amount of each component shown in Table 2 was blended.

<Formation of resist pattern>
An organic antireflection film forming agent (Nissan Chemical Co., ARC66) was applied to the wafer surface using a spin coater (CLEAN TRACK Lithius Pro i, Tokyo Electron), and then heated at 205 ° C. for 60 seconds to give a film thickness of 105 nm. An organic antireflection film was formed. On the surface of this substrate, each radiation sensitive resin composition was applied by spin coating using a clean track (Tokyo Electron Co., Ltd., ACT12), and soft-baked on a hot plate at 100 ° C. for 60 seconds to obtain a film thickness. A 0.10 μm resist film was formed. Next, using an ArF immersion exposure apparatus (NSR-S610C, Nikon Seiki Company), exposure was performed under the best focus condition with NA = 1.3 and quadropole optical conditions. For exposure, a 1 / 4-times projection scanner (NSR-S610C, Nikon Seiki Company) was used, the size on the reticle was 0.220 um chrome / 0.440 um pitch, and the mask bias was 0 nm. Thereafter, post-exposure baking was performed on the hot plate at the temperature shown in Table 3 for 60 seconds, followed by development with butyl acetate at 23 ° C. for 30 seconds and rinsing with 4-methyl-2-pentanol solvent for 10 seconds. After performing, it dried and formed the negative resist pattern.

<Evaluation>
Each of the formed resist patterns was evaluated as follows. The results are shown in Table 3.

[Sensitivity (mJ / cm ² )]
A mask having a dot pattern is exposed through immersion water so that the diameter of the hole pattern after reduced projection exposure is 0.055 μm, and the hole pattern formed has a hole size of 0.055 μm in diameter. The exposure amount was the optimum exposure amount, and this optimum exposure amount was the sensitivity (mJ / cm ² ). Note that a scanning electron microscope (Hitachi High-Technologies Corporation, CG4000) was used for length measurement. At this time, the sensitivity was judged to be good when the sensitivity was 16 (mJ / cm ² ) or less.

[Cross-sectional shape]
The cross-sectional shape of the 0.055 μm hole pattern in the sensitivity evaluation was observed using Hitachi High-Technologies Corporation, S-4800. The line width Lb in the middle of the resist pattern and the line width La in the upper part of the film are measured, and when the range is 0.9 ≦ (La / Lb) ≦ 1.1, “A” (determined as good), range The case of being outside was designated as “B” (determined as defective).

[Circularity]
At the optimum exposure amount, a 0.055 μm hole pattern formed on the resist coating film on the substrate was observed from above the pattern using a length measurement SEM (Hitachi High-Technologies Corporation, CG4000). The diameter was measured at an arbitrary point, and the measurement variation was evaluated by 3σ. When the diameter was 0.009 μm or less, it was judged as “good”, and when it exceeded 0.009 μm, it was judged as “bad”.

[Resolution]
Exposure was performed through immersion water using a mask having a dot pattern, and the minimum size of holes obtained when the exposure amount was increased was measured. When the minimum dimension of the hole was less than 0.050 μm, it was judged as “good”, and when it was 0.050 μm or more, it was judged as “bad”.

As is clear from Table 3, it was found that the composition used in the pattern forming method of the present invention was excellent in sensitivity, and the formed resist pattern was excellent in cross-sectional shape, circularity and resolution.

The present invention provides a method for forming a trench pattern or a hole pattern that is suitable for immersion exposure and has excellent lithography properties such as sensitivity, cross-sectional shape, circularity, and resolution, and a radiation-sensitive resin composition. Can do.

Claims (6)

1. (1) a resist film forming step of applying a radiation sensitive resin composition on a substrate;
   (2) An exposure step of irradiating the resist film with radiation through a photomask, and (3) a trench pattern or hole pattern forming method including a development step of developing the exposed resist film,
   The radiation sensitive resin composition is
   [A] a polymer in which the content of the structural unit having an acid dissociable group is 10 mol% or less,
   [B] a polymer in which the content ratio of the structural unit having an acid dissociable group exceeds 10 mol%, and [C] a radiation-sensitive acid generator,
   (3) The method for forming a trench pattern or a hole pattern, wherein the developer in the developing step contains 80% by mass or more of an organic solvent.
2. The pattern formation method according to claim 1, wherein the fluorine content of the [A] polymer is higher than that of the [B] polymer.
3. The pattern forming method according to claim 1, wherein the organic solvent is at least one organic solvent selected from the group consisting of ether solvents, ketone solvents and ester solvents.
4. [A] The polymer comprises at least one structural unit selected from the group consisting of the structural unit (I) represented by the following formula (1) and the structural unit (II) represented by the following formula (2): The pattern forming method according to claim 1.
   

   

   (In the formula (1), R ¹ is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. R ² is a linear or branched alkyl group having 1 to 6 carbon atoms or 4 carbon atoms. To 20 monovalent alicyclic hydrocarbon groups, provided that at least a part of the hydrogen atoms of the alkyl group and alicyclic hydrocarbon group are substituted with fluorine atoms.)
   

   

   (In Formula (2), R ³ is a hydrogen atom, a methyl group or a trifluoromethyl group. R ⁴ is an (m + 1) -valent linking group. X is a divalent linking group having a fluorine atom. R ⁵ is a hydrogen atom or a monovalent organic group, m is an integer of 1 to 3, provided that when there are a plurality of m, the plurality of X and R ⁵ are the same as each other. May be different.)
5. [B] The pattern forming method according to claim 1, wherein the acid dissociable group of the polymer has a chain hydrocarbon group or a monocyclic or polycyclic alicyclic hydrocarbon group.
6. (1) a resist film forming step of applying a radiation sensitive resin composition on a substrate;
   (2) An exposure step of irradiating the resist film with radiation through a photomask, and (3) a trench pattern or hole pattern forming method including a development step of developing the exposed resist film,
   The developer in the step (3) contains 80% by mass or more of an organic solvent,
   The radiation sensitive resin composition is
   [A] a polymer in which the content of the structural unit having an acid dissociable group is 10 mol% or less,
   [B] A polymer in which the content of the structural unit having an acid-dissociable group exceeds 10 mol%, and [C] a radiation-sensitive resin composition, comprising a radiation-sensitive acid generator.