WO2012046581A1 - Pattern forming method and radiation-sensitive resin composition - Google Patents

Abstract

The purpose of the present invention is to provide: a method for forming trench patterns and/or hole patterns, which is capable of forming patterns that minimize the occurrence of roughness on the upper patterned surface of a resist film, and that have excellent resolution, pattern size uniformity, cross-sectional shape, etc.; and a radiation-sensitive resin composition. The present invention is a method for forming trench patterns and/or hole patterns which includes, (1) a resist film forming step in which a radiation-sensitive resin composition is applied on a substrate, (2) an exposure step in which the resist film is exposed, and (3) a development step in which the exposed resist film is developed with a developing solution; said method being characterized in that the developing solution contains at least 80 mass % of an organic solvent, and the radiation-sensitive resin composition contains, [A] a polymer that includes a structural unit containing an acid dissociable group, and the polarity of which increases due to the effect of acid, [B] radiation-sensitive acid-generating body, and [C] an acid diffusion control body having a polar group.

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 a finer pattern formation is required.

As a means for enabling finer pattern formation, a technique for improving resolution by using an organic solvent having a polarity lower than that of an alkaline aqueous solution as a developer is known (see Japanese Patent Application Laid-Open No. 2000-199953). As described above, an advantage of using an organic solvent as a developer is that the optical contrast can be increased as compared with the case where a trench pattern or a hole pattern is formed using an alkaline aqueous solution.

However, in the development process using an organic solvent as the developer, there is a disadvantage that the acid generated in the exposed part of the resist film diffuses to the unexposed part and the dissolution contrast between the exposed part and the unexposed part becomes insufficient. . Therefore, in order to suppress an undesirable chemical reaction in the unexposed region of the resist film, an acid diffusion control agent has been added, but since the poor solubility in organic solvents is insufficient, an acid diffusion control agent is used. It has been pointed out that even when blended, roughness occurs on the upper surface of the pattern. Also, during the pre-baking (PB), evaporation of the acid diffusion control agent occurs, and there is a disadvantage that the T-top shape is generated in the trench pattern, the missing contact hole is generated in the hole pattern, and the pattern size is not uniform. .

In particular, in the method of forming a negative resist trench pattern and / or hole pattern using an organic solvent as the developer, an optimal radiation-sensitive resin composition that solves the above disadvantages, a developer to be used, and a combination thereof Has not been found to date.

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

The present invention has been made on the basis of the above circumstances, and its purpose is to satisfy the basic characteristics such as sensitivity in the lithography process, and to suppress the roughness of the upper surface of the pattern of the resist film, thereby improving the resolution. Another object of the present invention is to provide a trench pattern and / or hole pattern forming method and a radiation-sensitive resin composition that are excellent in pattern size uniformity, cross-sectional shape, and the like.

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 exposing the resist film; and (3) a trench pattern and / or hole pattern forming method including a development step of developing the exposed resist film with a developer,
The developer contains 80% by mass or more of an organic solvent,
The radiation sensitive resin composition is
[A] a polymer having a structural unit containing an acid dissociable group and having increased polarity by the action of an acid (hereinafter also referred to as “[A] polymer”),
[B] Radiation sensitive acid generator (hereinafter also referred to as “[B] acid generator”), and [C] Acid diffusion controller having a polar group (hereinafter also referred to as “[C] acid diffusion controller”). .)
It is a pattern formation method characterized by containing.

According to the pattern forming method of the present invention, the occurrence of roughness at the top of the resist pattern is suppressed. This is presumably because the [C] acid diffusion controller contained in the radiation-sensitive resin composition used in the forming method has a polar group, so that the solvent resistance to the organic developer in the resist film exposed portion is increased. In addition, since the [C] acid diffusion controller is likely to interact with the resin and other components via the polar group, it is difficult to evaporate in a treatment process at a high temperature such as PB. Therefore, according to the pattern formation method, the concentration distribution of the [C] acid diffusion controller in the film thickness direction of the resist film is difficult to be formed, and a pattern having excellent cross-sectional shape and pattern size uniformity can be formed. Conceivable.

[C] The acid diffusion controller is preferably a nitrogen-containing compound represented by the following formula (1).
(In the formula (1), R ¹ , R ² and R ³ are each independently a linear or branched alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms or an alkoxycarbonyl group. it. However, although any two of R 1 ^~ R ³ may be bonded to each other to form a hetero ring together with the nitrogen atom to which they are attached. However, R ^{1, R 2,} R ³ or above At least one of the heterocyclic hydrogen atoms is substituted with a polar group.)

[C] When the acid diffusion controller is a nitrogen-containing compound represented by the above formula (1), the acid diffusion controller has an appropriate basicity and is suitable for the diffusion phenomenon of acid generated from the acid generator upon exposure in the resist film. Can be controlled. Furthermore, since at least one of R ¹ , R ² , R ³ in the formula (1) or the hydrogen atom of the heterocycle is substituted with a polar group, according to the pattern formation method, the resist film at the time of pattern formation The occurrence of surface roughness is suppressed, and the uniformity in resolution, cross-sectional shape, and pattern size is also excellent.

The polar group is preferably a hydroxy group or a carboxy group. When the polar group is a hydroxy group or a carboxy group, it interacts with a lactone group or a polar group in the polymer via the polar group, so that transpiration in PB can be suppressed. As a result, according to the pattern forming method, the roughness of the resist film surface can be suppressed, and the uniformity in resolution, cross-sectional shape, and pattern size is excellent.

Any ^one of R ¹ , R ² and R ³ is preferably represented by the following formula (2).

(In Formula (2), R ⁴ , R ⁵ and R ⁶ are each independently a linear or branched alkyl group having 1 to 4 carbon atoms or a cycloalkyl group having 4 to 12 carbon atoms. However, R ⁴ and R ⁵ may be bonded to each other to form a cycloalkanediyl group having 4 to 12 carbon atoms together with the carbon atom to which they are bonded, * indicates a site bonded to a nitrogen atom. )

Said R ^1, R ² or R ³ is, to have a structure represented by the above formula (2), in order to improve the affinity of [C] the acid diffusion controller and the acid, [B] a radiation-sensitive acid generator It is thought that the acid generated from the body can be quickly captured. Moreover, since molecular weight becomes large, it becomes difficult to evaporate also in the case of PB.

[A] The acid dissociable group of the polymer preferably has an alicyclic group. [A] Since the polymer has an alicyclic group, the resist film can be made highly transparent with respect to an ArF excimer laser or the like. Therefore, according to the pattern forming method, a pattern with higher resolution can be formed.

It is preferable to perform multiple exposures in the above (2) exposure step. By doing so, according to the pattern formation method, it is possible to form a finer pattern with higher resolution.

In the present invention,
(1) a resist film forming step of applying a radiation sensitive resin composition on a substrate;
(2) An exposure step of exposing the resist film, and (3) A radiation-sensitive resin composition used in a trench pattern and / or hole pattern forming method including a development step of developing the exposed resist film with a developer. Because
The developer contains 80% by mass or more of an organic solvent,
The radiation sensitive resin composition is
[A] a polymer having a structural unit containing an acid-dissociable group and having increased polarity by the action of an acid;
The radiation sensitive resin composition characterized by containing [B] a radiation sensitive acid generator, and [C] the acid diffusion control body which has a polar group is also contained.

According to the pattern formation method of the present invention, the formation of a pattern that satisfies basic characteristics such as sensitivity and the occurrence of roughness on the upper surface of the resist film pattern and is excellent in resolution, pattern size uniformity, cross-sectional shape, etc. Is possible. Thereby, it is possible to sufficiently cope with various electronic device structures such as semiconductor devices and liquid crystal devices that require further miniaturization.

<Method for forming trench pattern and / or hole pattern>
The present invention includes (1) a resist film forming step of applying a radiation sensitive resin composition on a substrate, (2) an exposure step of exposing the resist film, and (3) developing the exposed resist film with a developer. A method of forming a trench pattern and / or a hole pattern including a developing step, wherein the developer in the (3) developing step contains 80% or more of an organic solvent, and the radiation sensitive resin composition is [A] A polymer having a structural unit containing an acid-dissociable group and having an increased polarity by the action of an acid, [B] a radiation-sensitive acid generator, and an acid diffusion controller having a [C] polar group It is characterized by. Hereinafter, each process is explained in full detail.

[Step (1)]
In this step, the composition used in the present invention is applied onto 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. Further, for example, an organic or inorganic antireflection film disclosed in Japanese Patent Publication No. 6-12452 and Japanese Patent Application Laid-Open No. 59-93448 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 composition, the solvent in the coating film may be volatilized by PB if necessary. The heating conditions for PB are appropriately selected depending on the composition of the composition, but are usually about 30 to 200 ° C, preferably 50 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)]
In this step, exposure is performed by reducing and projecting onto a desired region of the resist film formed in step (1) through a mask having a specific pattern and, if necessary, an immersion liquid. For example, an isotrench pattern can be formed by performing reduced projection exposure through a mask having an isoline pattern in a desired region. 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 [B] 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 and KrF excimer laser (wavelength 248 nm) are preferable, and ArF excimer laser is more preferable. The exposure conditions such as the exposure amount are appropriately selected according to the composition of the 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 composition can proceed smoothly. The heating conditions for PEB are usually 30 ° C. to 200 ° C., preferably 50 ° C. to 170 ° C.

[Step (3)]
In this step, after the exposure in step (2), development is performed using a negative developer containing 80% by mass or more of an organic solvent to form a trench pattern and / or a hole pattern. The negative developer is a developer that selectively dissolves and removes the low-exposed portion and the unexposed portion. The organic solvent used as the negative developer is at least one selected from the group consisting of alcohol solvents, ether solvents, ketone organic solvents, amide solvents, ester organic solvents, and hydrocarbon solvents. Is preferred.

Examples of alcohol solvents include methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, sec-butanol, tert-butanol, n-pentanol, i-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-heptadec Monoalcohol solvents such as 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 the ether solvent include diethyl ether, dipropyl ether, dibutyl ether, diphenyl ether and the like.

Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, diethyl ketone, methyl-i-butyl ketone, methyl-n-pentyl ketone, ethyl-n-butyl ketone, methyl-n- And ketone solvents such as hexyl ketone, di-i-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 ester solvents include diethyl carbonate, propylene carbonate, methyl acetate, ethyl acetate, γ-butyrolactone, γ-valerolactone, n-propyl acetate, n-butyl acetate, i-butyl acetate, sec-butyl acetate, isoamyl acetate. 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, methyl acetoacetate, Ethyl acetoacetate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monoacetate Non-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, glycol diacetate Methoxytriglycol acetate, ethyl propionate, n-butyl propionate, i-amyl propionate, diethyl oxalate, di-n-butyl oxalate, methyl lactate, ethyl lactate, n-butyl lactate, n-amyl lactate, Examples include diethyl malonate, dimethyl phthalate, and diethyl phthalate.

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

Of these, n-butyl acetate, isoamyl acetate, n-pentyl acetate, methyl ethyl ketone, methyl n-butyl ketone, and methyl n-pentyl ketone are preferred. These organic solvents may be used alone or in combination of two or more.

The content of the organic solvent in the developer is 80% by mass or more, preferably 90% by mass or more. Most preferably, it is 99 mass% or more. When the developer contains 80% by mass or more of the organic solvent, good development characteristics can be obtained, and a pattern with more excellent lithography characteristics can be formed. Examples of components other than the organic solvent include water, silicone oil, and surfactant.

An appropriate amount of a surfactant can be added to the developer as necessary. As the surfactant, for example, an ionic or nonionic fluorine-based and / or silicon-based surfactant can be used.

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] acid generator, and a [C] acid diffusion controller. [A] The polymer contains an acid dissociable group, and this acid dissociable group is dissociated by the action of the acid generated from the [B] acid generator. As a result, the polarity of the [A] polymer increases and the poor solubility in the exposed area increases. Since the radiation-sensitive resin composition used in the present invention further contains a [C] acid diffusion controller, the diffusion phenomenon of the acid generated from the [B] acid generator upon exposure in the resist film is controlled, and the unexposed region Undesirable chemical reactions in are suppressed. In addition, since the [C] acid diffusion controller has a polar group, the poor solubility of the exposed area in the negative developer increases, and the dissolution contrast between the exposed / unexposed areas increases. As a result, the solvent resistance to the organic developer above the pattern is increased, so that the roughness of the resist film surface is suppressed.
Moreover, the said composition may contain another arbitrary component, unless the effect of this invention is impaired. Hereinafter, each component will be described in detail.

<[A] polymer>
The polymer [A] is a polymer that contains a structural unit containing an acid dissociable group and whose polarity increases by the action of an acid.

[Structural unit (I)]
[A] The polymer preferably has a structural unit (I) represented by the following formula (3).

(In Formula (3), R ⁷ is a hydrogen atom, a methyl group or a trifluoromethyl group. R ^p is an acid-dissociable group.)

Group as the acid dissociable group represented by R ^p represented by the following formula (4) is preferable.

(In the formula (4), 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 a carbon number. An alkyl group having 1 to 4 or an alicyclic hydrocarbon group having 4 to 20 carbon atoms, wherein R ^p2 and R ^p3 are bonded to each other and have 4 to 20 carbon atoms together with the carbon atoms to which they are bonded. (A divalent alicyclic hydrocarbon group may be formed.)

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 a 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 a polycyclic alicyclic group having a bridged skeleton such as an adamantane skeleton and a norbornane skeleton. Group; a monocyclic alicyclic group having a cycloalkane skeleton such as cyclopentane or cyclohexane. These groups may be substituted with one or more of linear, branched or cyclic alkyl groups having 1 to 10 carbon atoms, for example.

Among these, R ^p1 is an alkyl group having 1 to 4 carbon atoms, R ^p2 and R ^p3 are bonded to each other, and each is a divalent group having an adamantane skeleton or a cycloalkane skeleton together with the bonded carbon atoms. Is preferably formed.

Examples of the structural unit (I) include structural units represented by the following formulas (1-1) to (1-4).

(In the formula (1-1) ~ (1-4), R 7 is ^{.R p1, R p2} and ^{R p3} as defined in the above formula (3) is as defined in the above formula (4) .n _p is (It is an integer from 1 to 3.)

Examples of the structural unit represented by the above formula (3) include a structural unit represented by the following formula.

(Wherein R ⁷ has the same meaning as the above formula (3))

[A] In the polymer, the content of the structural unit (I) is preferably such that the total amount of the structural unit (I) with respect to all the structural units constituting the [A] polymer is 20 mol% to 80 mol%. More preferably, it is 25 mol% to 70 mol%. In addition, the [A] polymer may have 1 type, or 2 or more types of structural units (I).

Monomers that give the structural unit (I) include monomers containing an acid-dissociable group having a monocyclic alicyclic group such as 1-alkyl-cycloalkyl ester, 2-alkyl-2-dicycloalkyl, etc. And monomers containing an acid-dissociable group having a polycyclic alicyclic group such as esters and 2-alkyl-2-tricycloalkyl esters.

[Structural unit (II)]
[A] The polymer preferably has a structural unit (II) containing a lactone structure. By having the structural unit (II), the adhesion of the resist film formed from the radiation-sensitive resin composition to the substrate can be improved. Here, the lactone structure represents a 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.

Examples of the structural unit (II) include structural units represented by the following formulas.

(In the formula, R ^L1 represents a hydrogen atom, a methyl group or a trifluoromethyl group.)

The monomer that generates the structural unit (II) is represented by the following formula (L-1).

(In the formula (L-1), R ^L1 is a hydrogen atom, a methyl group or a trifluoromethyl group. R ^L2 is a single bond or a divalent linking group. R ^L3 is a monovalent organic compound having a lactone structure. Group.)

Examples of the divalent linking group represented by R ^L2 include a divalent linear or branched hydrocarbon group having 1 to 20 carbon atoms.

Examples of the monovalent organic group having a lactone structure represented by R ^L3 include groups represented by the following formulas (L3-1) to (L3-6).

(In the formulas (L3-1) to (L3-6), R ^Lc1 is an oxygen atom or a methylene group. R ^Lc2 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. N _Lc1 is 0 or 1. N _Lc2 is an integer of 0 to 3. * represents a site that binds to R ^L2 in the above formula (L-1), provided that it is represented by formulas (L3-1) to (L3-6). Group may have a substituent.)

Examples of preferable monomers that give the structural unit (II) include monomers described in paragraph [0043] of International Publication No. 2007/116664.

[A] The content of the structural unit (II) in the polymer is preferably 20 mol% to 80 mol%, and more preferably 30 mol% to 70 mol%.

[A] The polymer may contain other structural units in addition to the structural unit (I) and the structural unit (II) as long as the effects of the present invention are not impaired. Examples of other structural units include structural units having a polar group.

<[A] Polymer Synthesis Method>
[A] The polymer 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 solution containing a monomer and a solution containing a radical initiator A method in which a polymerization reaction is carried out by dropping a reaction solvent or a monomer-containing solution separately; a plurality of types of solutions containing each monomer and a solution containing a radical initiator are separately added to the reaction solvent. Or it is preferable to synthesize | combine by methods, such as the method of dripping at the solution containing a monomer, and making it polymerize. In addition, when the monomer solution is dropped and reacted with respect to the monomer solution, the monomer amount in the dropped monomer solution is 30 mol with respect to the total amount of monomers used for polymerization. % Or more is preferable, 50 mol% or more is more preferable, and 70 mol% or more is particularly preferable.

The reaction temperature in these methods may be appropriately determined depending on the initiator type. Usually, it is 30 ° C to 180 ° C, preferably 40 ° C to 160 ° C, and more preferably 50 ° C to 140 ° C. 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, more preferably 1 hour to 5 hours. . The total reaction time including the dropping time varies depending on the conditions as in the dropping time, but is usually from 30 minutes to 8 hours, preferably from 45 minutes to 7 hours, and more preferably from 1 hour to 6 hours.

Examples of the radical initiator used in the polymerization include azobisisobutyronitrile (AIBN), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 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 Mw of the [A] polymer by GPC method is preferably 1,000 to 100,000, more preferably 2,000 to 50,000, and particularly preferably 3,000 to 30,000. [A] By making Mw of a polymer into the said range, the cross-sectional shape of a resist pattern becomes favorable.

[A] The ratio of Mw to Mn (Mw / Mn) of the polymer is usually 1 to 3, and preferably 1 to 2.

<[B] Acid generator>
[B] The acid generator generates an acid by exposure, and the acid dissociable group present in the [A] polymer is dissociated by the acid to generate a polar group such as a carboxy group. As a result, the [A] polymer becomes hardly soluble in the developer. The composition of the [B] acid generator in the composition is incorporated as part of the polymer even in the form of a compound as will be described later (hereinafter sometimes referred to as “[B] acid generator” as appropriate). Or both of these forms.

[B] Examples of the acid generator include onium salt compounds, sulfonimide compounds, halogen-containing compounds, diazoketone compounds, and the like. Of these [B] 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, 2-adamantyl-1,1-difluoroethane-1-sulfonate, and the like. Of these, triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, 2-adamantyl-1,1-difluoroethane-1-sulfonate and triphenylphosphonium 1,1,2,2-tetrafluoro- 6- (1-adamantanecarbonyloxy) -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.

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-difluoroethanesulfonyl Oxy) 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.

These [B] acid generators may be used alone or in combination of two or more. [B] The amount used when the acid generator is an acid generator is usually 0.1 mass with respect to 100 parts by mass of the polymer [A] from the viewpoint of ensuring sensitivity and developability as a resist. Part to 20 parts by mass, preferably 0.5 part to 15 parts by mass. [B] By making the usage-amount of an acid generator into the said specific range, sensitivity can fully be satisfied.

<[C] Acid diffusion controller>
[C] The acid diffusion controller controls the diffusion phenomenon in the resist film of the acid generated from the [B] acid generator by exposure, and has the effect of suppressing an undesirable chemical reaction in the non-exposed region, And if it has a polar group in the structure, it will not specifically limit. The radiation-sensitive resin composition used in the pattern forming method contains the [C] acid diffusion controller having a polar group, thereby adding an effect of adding a normal acid diffusion controller. In addition, the roughness of the upper surface of the pattern of the resist film obtained is suppressed. Further, the reverse taper shape is suppressed in the trench pattern, and the missing contact hole is suppressed in the hole pattern. The inclusion form of the acid diffusion controller in the composition may be in the form of a free compound, incorporated as part of the polymer, or both forms.

Examples of the acid diffusion controller include nitrogen compounds such as amine compounds, amide group-containing compounds, and urea compounds. Of these, nitrogen-containing compounds are preferred.

[C] The acid diffusion controller is preferably a nitrogen-containing compound represented by the above formula (1).

In the above formula (1), R ¹ , R ² and R ³ are each independently a linear or branched alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms or an alkoxycarbonyl group. It is. However, any two of R ¹ to R ³ may be bonded to each other and form a heterocycle together with the nitrogen atom to which they are bonded. In addition, at least one of R ¹ , R ² , R ³ or the hydrogen atom of the heterocycle is substituted with a polar group.

In the above formula (1), the linear or branched alkyl group having 1 to 10 carbon atoms represented by R ¹ , R ² and R ³ includes a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, A decyl group etc. are mentioned. Of these, a methyl group, an ethyl group, and a propyl group are preferable.
In the above formula (1), the cycloalkyl group having 3 to 20 carbon atoms represented by R ¹ , R ² and R ³ includes a cyclopropyl group, a cyclobutyl group, a cyclopentylpropyl group, a cyclohexylmethyl group, a cyclooctyl group, and a cyclooctyl group. A methyl group etc. are mentioned.
In the above formula (1), and any two of R 1 ^~ R ³ bonded to each other, the hetero ring they form together with the nitrogen atom to which they are bonded, a pyrazine ring, a pyrazole ring, a pyridazine ring, quinoxaline ring, Examples include a purine ring, a pyrrolidine ring, and a piperidine ring. Of these, pyrrolidine ring and piperidine ring are preferred.

In the above formula (1), R ¹ , R ² or R ³ is preferably a group represented by the above formula (2). The group represented by the above formula (2) is a group having an acid dissociable group. In the [C] acid diffusion controller in the present invention, the acid dissociable group is dissociated by the action of an acid, and the basic amino Be the basis. Thereby, it has the effect of improving the lithography performance of the resist film obtained from the radiation sensitive resin composition of the present invention.

In the above formula (1), examples of the polar group possessed by the groups represented by R ¹ to R ³ include a hydroxy group, a carboxy group, a cyano group, an amino group, and an amide group. Of these, a hydroxy group or a carboxy group is preferable. [C] The acid diffusion controller has one or more polar groups, and more preferably 1 to 3 polar groups.

In the above formula (2), R ⁴ , R ⁵ and R ⁶ are each independently a linear or branched alkyl group having 1 to 4 carbon atoms or a cycloalkyl group having 4 to 12 carbon atoms. However, R ⁴ and R ⁵ may be bonded to each other to form a cycloalkanediyl group having 4 to 12 carbon atoms together with the carbon atom to which they are bonded. * Indicates a site bonded to a nitrogen atom.

In the above formula (2), examples of the linear or branched alkyl group having 1 to 4 carbon atoms represented by R ⁴ , R ⁵ and R ⁶ include a methyl group, an ethyl group, a propyl group and a butyl group. Of these, a methyl group and an ethyl group are preferred.
In the above formula ^(2), a monovalent alicyclic hydrocarbon group R 4, ^{R 5} and 4 to 12 carbon atoms ^{R 6} represents, and ^{R 4} and ^{R 5} are bonded to each other, and they are attached Examples of the alicyclic hydrocarbon group having 4 to 12 carbon atoms formed together with the carbon atom include cycloalkyl groups such as cyclobutyl group, cyclopentyl group, cyclohexyl group, cyclooctyl group, norbornyl group, tricyclodecyl group, tetra Examples thereof include a group derived from a bridged alicyclic group such as a cyclododecyl group and an adamantyl group.

Examples of the group represented by the above formula (2) include a group represented by the following formula.

Of these, (2-16) and (2-17) are preferred.

The [C] acid diffusion controller comprising a group having an acid dissociable group represented by the above formula (2) is a compound that is dissociated by the action of an acid to form a basic amino group, It has the effect of improving the lithography performance of a resist obtained from the radiation-sensitive resin composition in the pattern forming method. At this time, by increasing the number of carbon atoms of the dissociable group of the acid dissociable group, the dissociation ability of the dissociable group is improved, and the basicity in the resist film can be easily controlled. Furthermore, since the evaporation of the [C] acid diffusion controller from the resist film during PB before exposure or post-exposure baking after exposure is suppressed, lithography performance can be further improved. The number of carbon atoms of the dissociating group is preferably 4-20, and more preferably 4-13. When it is a hydrocarbon group having 4 or more carbon atoms, dissociation by an acid is likely to occur.

[C] The acid diffusion controller is preferably represented by the following formula.

These acid diffusion inhibitors may be used alone or in combination of two or more. [C] The content of the acid diffusion controller is preferably 15 parts by mass or less, more preferably 0.001 to 10 parts by mass, and particularly preferably 0.005 to 100 parts by mass with respect to 100 parts by mass of the [A] polymer. 5 parts by mass. When the content of the acid diffusion control agent is less than 0.001 part by mass, the pattern shape tends to deteriorate, and when it exceeds 15 parts by mass, the sensitivity as a resist tends to decrease.

<Other ingredients>
The radiation-sensitive resin composition is [D] a polymer having a fluorine atom (hereinafter also referred to as “[D] polymer”) and an [E] solvent, as long as the effects of the present invention are not impaired. As other optional components, a surfactant, an alicyclic skeleton-containing compound, and a sensitizer can be contained. Hereinafter, each component will be described in detail.

([D] polymer)
[D] The polymer is a polymer having a fluorine atom. The radiation-sensitive resin composition in the pattern formation contains the [D] polymer, thereby improving the hydrophobicity of the resist film and being excellent in suppressing 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. [D] polymer in this invention is formed by superposing | polymerizing 1 or more types of the monomer which contains a fluorine in a structure.

Examples of the monomer containing fluorine in the structure include those containing a fluorine atom in the main chain, those containing a fluorine atom in the side chain, and those containing a fluorine atom in the main chain and the side chain.
Examples of monomers containing fluorine atoms in the main chain include α-fluoroacrylate compounds, α-trifluoromethyl acrylate compounds, β-fluoroacrylate compounds, β-trifluoromethyl acrylate compounds, α, β-fluoroacrylate compounds. , Α, β-trifluoromethyl acrylate compounds, compounds in which hydrogen at one or more types of vinyl sites is substituted with fluorine or a trifluoromethyl group, and the like.
Examples of the monomer containing a fluorine atom in the side chain include those in which the side chain of an alicyclic olefin compound such as norbornene is fluorine or a fluoroalkyl group or a derivative thereof, or a fluoroalkyl of acrylic acid or methacrylic acid. And an ester compound of a group or a derivative thereof, and one or more olefin side chains (parts not including a double bond) are fluorine or a fluoroalkyl group or a derivative thereof.
Furthermore, examples of the monomer containing a fluorine atom in the main chain and the side chain include α-fluoroacrylic acid, β-fluoroacrylic acid, α, β-fluoroacrylic acid, α-trifluoromethylacrylic acid, β- An ester compound of a fluoroalkyl group such as trifluoromethylacrylic acid or α, β-trifluoromethylacrylic acid or a derivative thereof, or a compound in which hydrogen at one or more vinyl sites is substituted with fluorine or a trifluoromethyl group The chain is substituted with a fluorine or fluoroalkyl group or a derivative thereof, the hydrogen bonded to the double bond of one or more alicyclic olefin compounds is substituted with a fluorine atom or a trifluoromethyl group, and the side chain In which is a fluoroalkyl group or a derivative thereof. In addition, an alicyclic olefin compound here shows the compound in which a part of ring is a double bond.

In the present invention, the structural unit for imparting fluorine to the [D] polymer is not particularly limited, but the structural unit (III) represented by the following formula (5) is used as the fluorine-providing structural unit. Is preferred.

(In the formula (5), R ⁸ is hydrogen, a fluorine atom, a methyl group or a trifluoromethyl group. A is a linking group. R ⁹ has 1 to 6 carbon atoms containing at least one fluorine atom.) A linear or branched alkyl group, or an alicyclic hydrocarbon group having 4 to 20 carbon atoms containing at least one fluorine atom or a derivative thereof.)

In the above formula (5), examples of the linking group represented by A include a single bond, an oxygen atom, a sulfur atom, a carbonyloxy group, an oxycarbonyl group, an amide group, a sulfonylamide group, and a urethane group.

Monomers that give structural unit (III) include trifluoromethyl (meth) acrylate, 2,2,2-trifluoroethyl (meth) acrylate, perfluoroethyl (meth) acrylate, Fluoro 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- (2,2,3,3,4,4,4) 5,5-octafluoropentyl) (meth) acrylic acid ester, perfluorocyclohexylmethyl (meth) acrylic Acid ester, 1- (2,2,3,3,3-pentafluoropropyl) (meth) acrylic acid ester, 1- (3,3,4,4,5,5,6,6,7,7, 8,8,9,9,10,10,10-heptadecafluorodecyl) (meth) acrylic acid ester, 1- (5-trifluoromethyl-3,3,4,4,5,6,6,6 -Octafluorohexyl) (meth) acrylic acid ester and the like.

[D] The polymer may have only one type of structural unit (III), or may have two or more types. [D] The content of the structural unit (III) in the polymer is preferably 10 mol% or more and 80 mol% or less when the total structural unit in the [D] polymer is 100 mol%, preferably 20 mol%. % To 50% is more preferable. If the content of the structural unit (III) is less than 10 mol%, a receding contact angle of 70 degrees or more cannot be achieved, and elution of the acid generator and the like from the resist film may not be suppressed.

[D] In addition to the structural unit (III), the polymer includes, for example, a structural unit having an acid-dissociable group, a lactone skeleton, a hydroxyl group, a carboxyl group, etc. in order to control the dissolution rate in the developer. One or more “other structural units” such as a structural unit derived from an aromatic compound can be contained in order to suppress scattering of light due to reflection from the unit, a structural unit having an alicyclic compound, and the like.

The description of the structural unit (I) of the polymer [A] can be applied to the structural unit having the acid dissociable group.

As the structural unit containing the lactone skeleton, the description of the structural unit (II) of the polymer [A] can be applied.

Examples of the structural unit having the alicyclic compound include a structural unit (IV) represented by the following formula (6).

(In formula (6), R ¹⁰ is a hydrogen atom, a methyl group, or a trifluoromethyl group. B is an alicyclic hydrocarbon group having 4 to 20 carbon atoms.)

Examples of the alicyclic hydrocarbon group having 4 to 20 carbon atoms represented by B in the above formula (6) include cyclobutane, cyclopentane, cyclohexane, bicyclo [2.2.1] heptane, and bicyclo [2.2. 2] Octane, tricyclo [5.2.1.0 ^2,6 ] decane, tetracyclo [6.2.1.1 ^3,6 . And hydrocarbon groups composed of alicyclic rings derived from cycloalkanes such as 0 ^2,7 ] dodecane and tricyclo [3.3.1.1 ^3,7 ] decane. One or all of the hydrogen atoms contained in these cycloalkane-derived alicyclic rings may be substituted with a substituent. Examples of the substituent include a linear, branched or cyclic alkyl group having 1 to 4 carbon atoms, a hydroxyl group, a cyano group, a hydroxyalkyl group having 1 to 10 carbon atoms, a carboxyl group, and oxygen.

Monomers that give the structural unit (IV) include (meth) acrylic acid-bicyclo [2.2.1] hept-2-yl ester, (meth) acrylic acid-bicyclo [2.2.2] octa -2-yl ester, (meth) acrylic acid-tricyclo [5.2.1.0 ^2,6 ] dec-7-yl ester, (meth) acrylic acid-tetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] dodec-9-yl ester, (meth) acrylic acid-tricyclo [3.3.1.1 ^3,7 ] dec-1-yl ester, (meth) acrylic acid-tricyclo [3.3. ^1.1,7 ] dec-2-yl ester and the like are preferable.

Examples of the monomer that gives the structural unit (V) derived from the aromatic compound include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-methoxystyrene, 3-methoxystyrene, 4-methoxystyrene, 4- (2-t-butoxycarbonylethyloxy) styrene 2-hydroxystyrene, 3-hydroxystyrene, 4-hydroxystyrene, 2-hydroxy-α-methylstyrene, 3-hydroxy -Α-methylstyrene, 4-hydroxy-α-methylstyrene, 2-methyl-3-hydroxystyrene, 4-methyl-3-hydroxystyrene, 5-methyl-3-hydroxystyrene, 2-methyl-4-hydroxystyrene , 3-methyl-4-hydroxystyrene, 3,4-dihydroxy Tylene, 2,4,6-trihydroxystyrene, 4-t-butoxystyrene, 4-t-butoxy-α-methylstyrene, 4- (2-ethyl-2-propoxy) styrene, 4- (2-ethyl- 2-propoxy) -α-methylstyrene, 4- (1-ethoxyethoxy) styrene, 4- (1-ethoxyethoxy) -α-methylstyrene, phenyl (meth) acrylate, benzyl (meth) acrylate, acenaphthylene, 5-hydroxyacenaphthylene, 1-vinylnaphthalene, 2-vinylnaphthalene, 2-hydroxy-6-vinylnaphthalene, 1-naphthyl (meth) acrylate, 2-naphthyl (meth) acrylate, 1-naphthylmethyl (meth) acrylate 1-anthryl (meth) acrylate, 2-anthryl (meth) acrylate, 9-an Examples include tolyl (meth) acrylate, 9-anthrylmethyl (meth) acrylate, and 1-vinylpyrene.

The [D] polymer in the present invention may have only one type of the other structural units (I), (II), (IV) or (V), or two or more types. May be. The content of these structural units is usually 0 mol% or more and 80 mol% or less, preferably 0 mol% or more and 75 mol% or less when the total structural unit in the [D] polymer is 100 mol%, 0 mol% or more and 70 mol% or less are more preferable.

[D] The amount of the polymer used is preferably 1 part by mass or more and 15 parts by mass or less, and more preferably 2 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the [A] polymer.

[D] The fluorine atom content in the polymer is preferably larger than that of the polymer [A]. [D] The fluorine atom content in the polymer is usually 5% by mass or more, preferably 5% by mass to 50% by mass, more preferably 5% by mass, with the total amount of the [D] polymer being 100% by mass. % By mass to 45% by mass. The fluorine atom content can be measured by ¹³ C-NMR. [D] A photoresist formed of a radiation-sensitive resin composition containing the [D] polymer and the [A] polymer, when the fluorine atom content in the polymer is larger than that of the [D] polymer. The water repellency of the film surface can be increased, and there is no need to separately form an upper layer film during immersion exposure. In order to sufficiently exhibit the above effect, the difference between the fluorine atom content in the [A] polymer and the fluorine atom content in the [D] polymer is 1% by mass or more. Preferably, it is 5 mass% or more.

<[D] Polymer Synthesis Method>
The [D] polymer is the same as the above-described method for synthesizing the [A] polymer by polymerizing, for example, a monomer corresponding to each predetermined structural unit in a suitable solvent using a radical polymerization initiator. It can manufacture by the method of.

[D] 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.

[D] The ratio (Mw / Mn) between the Mw of the polymer and the polystyrene-equivalent number average molecular weight (Mn) by the GPC method is usually 1 to 3, preferably 1 to 2.

([E] solvent)
The composition usually contains a solvent. The solvent is particularly limited as long as it can dissolve at least the above-mentioned [A] polymer, [B] acid generator, [C] acid diffusion controller, and [D] polymer added as necessary, and other optional components. Not. 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, cyclohexanone and γ-butyrolactone are preferred. These solvents may be used alone or in combination of two or more.

<Other optional components>
The composition may contain various additives for the purpose of adjusting or improving patterning characteristics and substrate processing characteristics.

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

(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)
A sensitizer represents the effect | action which increases the production amount of a [B] acid generator, and there exists an effect which improves the "apparent sensitivity" of the said composition.

<Preparation of radiation-sensitive resin composition>
The composition contains, for example, [A] polymer, [B] acid generator, [C] acid diffusion controller, [D] polymer added as necessary, and other components in an organic solvent. It can be prepared by mixing in proportions. In addition, the composition can be prepared and used in a state dissolved or dispersed in a suitable organic solvent.

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

Mw and Mn of the polymer were measured under the following conditions using GPC columns (Tosoh Corporation, 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

¹ H-NMR analysis and ¹³ C-NMR analysis were measured using a nuclear magnetic resonance apparatus (JEOL Ltd., JNM-EX270).

<[A] Synthesis of polymer>

[A] The monomer used for the synthesis of the polymer is represented by the following formula.

 

[Synthesis Example 1]: Synthesis of (A-1) 12.9 g (50 mol%) of a monomer represented by the following formula (M-1) and a monomer 17 represented by the formula (M-2) A solution was prepared by dissolving 0.1 g (50 mol%) in 2-butanone 60 g and adding 0.50 g of 2,2′-azobis (isobutyronitrile). Next, a 200 mL three-necked flask charged with 30 g of 2-butanone 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 using a dropping funnel. It was added dropwise over time. 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, 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 with 120 g of methanol twice as a slurry, then filtered again and dried at 50 ° C. for 12 hours to obtain a white powder polymer (A-1) (Mw = 13,000, Mw / Mn = 1.56, yield = 82%). The proportion of structural units derived from (M-1) / (M-2) in (A-1) was 49/51 (mol%).

[Synthesis Examples 2 to 4]
Polymers (A-2) to (A-4) were obtained in the same manner as in Synthesis Example 1 except that the types and amounts of monomers listed in Table 1 were used. Moreover, it shows in Table 1 together with the content rate of each structural unit of each obtained polymer, Mw, Mw / Mn ratio, and a yield (%).

<[D] Synthesis of polymer>

[D] The monomer used for the synthesis of the polymer is represented by the following formula.

[Synthesis Example 5]: Synthesis of (D-1) 35.8 g (70 mol%) of a monomer represented by the following formula (M-6) and 14.2 g of a monomer represented by the formula (M-7) ( 30 mol%) was dissolved in 50 g of 2-butanone, and a solution in which 5.17 g of dimethyl-2.2′-azobisisobutyrate was further added was prepared. Next, a 500 mL three-necked flask charged with 50 g of 2-butanone 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 using a dropping funnel for 3 hours. It was dripped over. 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 is cooled with water and cooled to 30 ° C. or lower. The reaction solution is transferred to a 2 L separatory funnel, and then the polymerization solution is uniformly diluted with 150 g of n-hexane, and 600 g of methanol is added. And mixed. Next, 30 g of distilled water was added, and the mixture was further stirred and allowed to stand for 30 minutes. Thereafter, the lower layer was collected to obtain a propylene glycol monomethyl ether acetate solution. Thus, a polymer (D-1) was obtained (Mw = 7,000, Mw / Mn = 1.60, yield = 66%). The ratio of structural units derived from (M-6) / (M-7) in (D-1) was 71/29 (mol%).

[Synthesis Example 6]
A polymer (D-2) was obtained in the same manner as in Synthesis Example 5 except that the types and amounts of monomers listed in Table 2 were used. Table 2 shows the structural unit content, Mw, Mw / Mn ratio, yield (%), and low molecular weight component content of the obtained polymer.

The [B] acid generator, [C] acid diffusion inhibitor and [E] solvent used in the preparation of the radiation sensitive resin composition are as follows.

<[B] Acid generator>
B-1: triphenylsulfonium 1,1,2,2-tetrafluoro-6- (1-adamantanecarbonyloxy) -hexane-1-sulfonate represented by the following formula B-2: represented by the following formula Triphenylsulfonium 2-adamantyl-1,1-difluoroethane-1-sulfonate

<[C] Acid diffusion controller>
C-1 to C-6: Compounds represented by the following formulae

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

<Preparation of radiation-sensitive resin composition>
[Example 1]
100 parts by weight of polymer (A-1), 12.8 parts by weight of acid generator (B-1), 1.7 parts by weight of acid diffusion controller (C-1), 3 parts by weight of polymer (D-1) And a solvent (E-1) 2,185 parts by mass, (E-2) 935 parts by mass, and (E-3) 30 parts by mass were prepared to prepare a radiation sensitive resin composition (R-1). .

[Examples 2 to 9, Comparative Examples 1 and 2]
The same procedure as in Example 1 except that the types and amounts of [A] polymer, [B] acid generator, [C] acid diffusion controller and [D] polymer described in Table 3 were used. Radiation sensitive resin compositions (R-2) to (R-11) were prepared.

 

<Formation of resist pattern>
[Example 10]
An organic antireflective film forming agent (Nissan Chemical Co., ARC66) was applied to the wafer surface to form an organic antireflective film having a film thickness of 105 nm. On the surface of this substrate, the radiation sensitive resin composition (R-1) was applied by spin coating using a clean track (Tokyo Electron, ACT12), and soft baking was performed on a hot plate at 90 ° C. for 60 seconds. Then, a resist film having a thickness of 0.10 μm was formed. Using pure water as the immersion liquid, the resist film is immersed between the dot pattern mask and the resist film using a full-field reduction projection exposure apparatus (Nikon Corporation, S610C, numerical aperture 1.30, illumination quadrupole). Through a reduced projection exposure. Thereafter, post exposure baking at 105 ° C. for 60 seconds, development with butyl acetate at 23 ° C. for 30 seconds, rinsing with 4-methyl-2-pentanol solvent for 10 seconds, rotation speed of 2, The wafer was dried by rotating it at 000 rpm for 10 seconds to form a negative resist pattern.

[Examples 11 to 28 and Comparative Examples 3 to 6]
A resist pattern was formed in the same manner as in Example 10 except that the radiation-sensitive resin composition of the type described in Table 4 and the developer were used.

<Evaluation>
Each of the formed resist patterns was evaluated as follows. The results are shown in Table 4.

[Roughness of resist surface (nm)]
The roughness of the resist surface was measured using an atomic force microscope (0.100 × 0.100 μm). When the roughness of the resist surface was measured and the value calculated by RMS was less than 10 nm, it was judged as “good”, and when it was 10 nm or more, it was judged as “bad”.

[Sensitivity (mJ / cm ² )]
A mask having a dot pattern is exposed through immersion water so that the hole pattern diameter after reduced projection exposure is 0.055 μm and the pitch is 0.110 μm, and the formed hole pattern has a diameter of 0.055 μm, The exposure amount when the pitch becomes a hole size of 0.110 μm was defined as the optimum exposure amount, and this optimum exposure amount was defined as sensitivity (mJ / cm ² ). Note that a scanning electron microscope (Hitachi High-Technologies Corporation, CG4000) was used for length measurement.

[Resolution (nm)]
The hole pattern obtained when the exposure dose is increased through immersion water through a mask having a dot pattern such that the diameter of the hole pattern after reduced projection exposure is 0.055 μm and the pitch is 0.110 μm. The smallest dimension was measured. When there was no missing contact and the minimum dimension of the hole was less than 55 nm, it was judged as “good”, and when the missing contact occurred or when the minimum dimension of the hole was 55 nm or more, it was judged as “bad”.

[Pattern size uniformity (CDU)]
At the optimum exposure amount, a 0.055 μm hole pattern formed in the resist film on the substrate was observed from the upper part of 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 0.004 μm or less, it was judged as “good”, and when it exceeded 0.004 μm, it was judged as “bad”.

[Cross-sectional shape]
In the above sensitivity evaluation, the cross-sectional shape of the 0.055 μm hole pattern was observed (Hitachi High-Technologies Corporation, S-4800). When the rectangular shape was shown, the line width Lb in the middle of the resist pattern and the upper part of the film The line width La was measured, and the case where it was within the range of 0.9 ≦ (La / Lb) ≦ 1.1 was evaluated as “good”, and the case where it was out of the above range was evaluated as “bad”.

As can be seen from Table 4, it was found that the resist pattern formed by the pattern forming method of the present invention was excellent in cross-sectional shape, pattern size uniformity and resolution. Moreover, the roughness of the pattern upper surface was also suppressed compared with the comparative example.

According to the present invention, in the lithography process, the roughness of the upper surface of the pattern of the resist film can be suppressed, and a pattern having excellent resolution, pattern size uniformity, cross-sectional shape, and the like can be formed. Thereby, it is possible to sufficiently cope with various electronic device structures such as semiconductor devices and liquid crystal devices that require further miniaturization.

Claims (7)

1. (1) a resist film forming step of applying a radiation sensitive resin composition on a substrate;
   (2) an exposure step of exposing the resist film; and (3) a trench pattern and / or hole pattern forming method including a development step of developing the exposed resist film with a developer,
   The developer contains 80% by mass or more of an organic solvent,
   The radiation sensitive resin composition is
   [A] a polymer having a structural unit containing an acid-dissociable group and having increased polarity by the action of an acid;
   [B] A pattern forming method comprising a radiation sensitive acid generator, and [C] an acid diffusion controller having a polar group.
2. [C] The pattern formation method according to claim 1, wherein the acid diffusion controller is a nitrogen-containing compound represented by the following formula (1).
   

   

   (In the formula (1), R ¹ , R ² and R ³ are each independently a linear or branched alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or alkoxycarbonyl. Provided that any two of R ¹ to R ³ are bonded to each other and may form a heterocycle together with the nitrogen atom to which they are bonded, and R ¹ , R ² , R ³ or At least one of the hydrogen atoms in the heterocycle is substituted with a polar group.)
3. The pattern forming method according to claim 1, wherein the polar group is a hydroxy group or a carboxy group.
4. The pattern forming method according to claim 2, wherein any one of R ¹ , R ^2, and R ³ is a group represented by the following formula (2).
   

   

   (In Formula (2), R ⁴ , R ⁵ and R ⁶ are each independently a linear or branched alkyl group having 1 to 4 carbon atoms or a cycloalkyl group having 4 to 12 carbon atoms. However, bound R ⁴ and R ⁵ together, they may form a cycloalkane-diyl group having 4 to 12 carbon atoms with the carbon atom bonded. * indicates a site binding to a nitrogen atom. )
5. [A] The pattern forming method according to any one of claims 1 to 4, wherein the acid dissociable group of the polymer has an alicyclic group.
6. The pattern forming method according to any one of claims 1 to 5, wherein the exposure is performed a plurality of times in the (2) exposure step.
7. (1) a resist film forming step of applying a radiation sensitive resin composition on a substrate;
   (2) An exposure step of exposing the resist film, and (3) A radiation-sensitive resin composition used in a trench pattern and / or hole pattern forming method, including a development step of developing the exposed resist film with a developer. Because
   The developer contains 80% by mass or more of an organic solvent,
   The radiation sensitive resin composition is
   [A] a polymer having a structural unit containing an acid-dissociable group and having increased polarity by the action of an acid;
   [B] A radiation sensitive resin composition comprising a radiation sensitive acid generator, and [C] an acid diffusion controller having a polar group.