JP2006058842A - Resist composition and method of forming resist pattern - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resist composition capable of reducing the elution of a substance into a solvent used in an immersion lithography process, and to provide a method of forming a resist pattern using the resist composition. <P>SOLUTION: The resist composition contains, as an acid generator ingredient (B), an onium salt type acid generator (B1) represented by the general formula (b-1) (wherein R<SP>11</SP>to R<SP>13</SP>each independently represent aryl or alkyl, provided that at least one of R<SP>11</SP>to R<SP>13</SP>represents aryl in which at least one hydrogen atom has been replaced with alkyl; and Z<SP>-</SP>represents an anion) or an onium salt type acid generator (B2) having a cyclic-group-containing anion. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a resist composition used in a resist pattern forming method including an immersion lithography (immersion exposure) step, and a resist pattern forming method using the resist composition.

Lithography is frequently used to manufacture fine structures in various electronic devices such as semiconductor devices and liquid crystal devices. At present, in the lithography method, for example, in a state-of-the-art region using an ArF excimer laser, it is possible to form a fine resist pattern having a line width of about 90 nm. Therefore, further miniaturization of the resist pattern is required. As a miniaturization means for achieving miniaturization of a resist pattern, a short wavelength light source wavelength using a light source having a shorter wavelength, for example, an F ₂ laser, EUV (extreme ultraviolet light), EB (electron beam), X-ray or the like. Generally, increasing the numerical aperture (NA) of an exposure apparatus lens (NA) is common. In addition, as a resist that satisfies such high sensitivity to a short wavelength light source and high resolution capable of reproducing a pattern with a fine dimension, a base resin whose alkali solubility is changed by the action of an acid, and an acid upon exposure. There is known a chemically amplified resist composition containing an acid generator that generates acid. However, shortening the light source wavelength requires a new expensive exposure apparatus. Further, the increase in NA has a limit because NA and the depth of focus are in a trade-off relationship, and it is difficult to achieve resolution without reducing the depth of focus.

Under such circumstances, a method called immersion lithography has been reported (for example, see Non-Patent Documents 1 to 3). In this method, a solvent having a refractive index larger than the refractive index of air, for example, a portion between a lens and a resist layer on the wafer, which is conventionally filled with an inert gas such as air or nitrogen, is exposed during exposure. In this method, exposure (immersion exposure) is performed in a state filled with a solvent such as pure water or a fluorine-based inert liquid. According to such immersion lithography, even when a light source with the same exposure wavelength is used, the same high resolution as when a light source with a shorter wavelength or a high NA lens is used can be achieved, and the depth of focus can be achieved. It is said that there is no decline in width. Immersion lithography can be performed using an existing exposure apparatus. Therefore, immersion lithography is expected to be able to form resist patterns with low cost, high resolution, and excellent depth of focus, and it is costly in the manufacture of semiconductor devices that require large capital investment. In addition, in terms of lithography characteristics such as resolution, the semiconductor industry is attracting a great deal of attention.
Journal of Vacuum Science & Technology B (USA), 1999, Vol. 17, No. 6, pp. 3306-3309. Journal of Vacuum Science & Technology B (USA), 2001, Vol. 19, No. 6, pp. 2353-2356. Proceedings of SPIE (USA) 2002, 4691, pp. 459-465.

However, it is still unclear whether a resist pattern as good as the conventional normal exposure process can be formed by immersion lithography. For example, in immersion lithography, as described above, the solvent contacts the resist layer and the lens during exposure. For this reason, the resist layer changes in quality due to elution of the substances contained in the resist into the solvent, etc., and the performance of the resist layer deteriorates. It can be considered that the resist pattern formation is adversely affected by contamination of the resist pattern. That is, problems such as deterioration in sensitivity, a resulting resist pattern having a T-top shape, and surface roughness and swelling of the resist pattern are expected. The present invention has been made in view of the above circumstances, and provides a resist composition capable of reducing substance elution into a solvent used in an immersion lithography process, and a resist pattern forming method using the resist composition. With the goal.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have eluted an onium salt acid generator having a specific cyclic structure in the anion part or cation part into the solvent used in the immersion lithography process. As a result, the present invention has been completed. That is, the first aspect of the present invention includes a step of immersion exposure, which includes a resin component (A) whose alkali solubility is changed by the action of an acid and an acid generator component (B) that generates an acid upon exposure. A resist composition used for a resist pattern forming method, wherein the acid generator component (B) contains an onium salt acid generator (B1) represented by the following general formula (b-1): The resist composition is characterized.

［式中、Ｒ^１１〜Ｒ^１３は、それぞれ独立に、アリール基またはアルキル基を表し、Ｒ^１１〜Ｒ^１３のうち少なくとも１つは、少なくとも１つの水素原子がアルキル基で置換されたアリール基を表し、Ｚ⁻はアニオンを表す。］

[Wherein, R ^{11 to} R ¹³ each independently represents an aryl group or an alkyl group, and at least one of R ^{11 to} R ¹³ represents an aryl group in which at least one hydrogen atom is substituted with an alkyl group. represents, Z ^- represents an anion. ]

Moreover, the 2nd aspect of this invention contains the resin component (A) from which alkali solubility changes with the effect | action of an acid, and the acid generator component (B) which generate | occur | produces an acid by exposure, and includes the process of immersion exposure. A resist composition for use in a resist pattern forming method, wherein the acid generator component (B) contains an onium salt acid generator (B2) having a cyclic group-containing anion. It is a thing.

According to a third aspect of the present invention, there is provided a resist pattern forming method using the resist composition of the first aspect or the second aspect, comprising a step of immersion exposure. It is.

According to the resist composition and the resist pattern forming method of the present invention, substance elution into a solvent (hereinafter sometimes referred to as an immersion medium) used in an immersion lithography process can be reduced.

Hereinafter, the present invention will be described in more detail. << Resist Composition of First Aspect >> The resist composition of the first aspect of the present invention includes a resin component (A) whose alkali solubility is changed by the action of an acid (hereinafter sometimes referred to as component (A)) and And an acid generator component (B) (hereinafter also referred to as component (B)) that generates an acid upon exposure, and is used in a resist pattern forming method including a step of immersion exposure, The component B) contains an onium salt acid generator (B1) represented by the general formula (b-1).

<Component (B)> In formula (b-1), R ^{11 to} R ¹³ each independently represents an aryl group or an alkyl group, and at least one of R ^{11 to} R ¹³ is at least one hydrogen atom. Must be an aryl group substituted with an alkyl group. By having such a structure, the elution of the cation portion of the onium salt acid generator (B1) into the immersion medium is reduced, and as a result, the elution of the substance into the immersion medium can be reduced.

The aryl group of R ¹¹ to R ^13, not particularly limited, for example, an aryl group having 6 to 20 carbon atoms, an alkyl group, a phenyl group which may not be substituted with a halogen atom or the like And a naphthyl group. An aryl group having 6 to 10 carbon atoms is preferable because it can be synthesized at a low cost, and a phenyl group is particularly preferable. The alkyl group of R ¹¹ to R ^13, not particularly limited, for example, a straight, include alkyl groups such as branched or cyclic. It is preferable that it is C1-C5 from the point which is excellent in resolution. Specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an n-pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a nonyl group, and a decanyl group. A methyl group is preferable because it is excellent in resolution and can be synthesized at low cost. Among ^these, it is preferable that two or more of R 11 ^{to R 13} is an aryl ^group, more preferably all of R 11 ^{to R 13} is an aryl ^group, R 11 ^{to R 13} in all phenyl groups Most preferably it is.

In addition, the alkyl group in the “aryl group in which at least one hydrogen atom is substituted with an alkyl group” is not particularly limited, and examples thereof include a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms. It is done. Among them, a branched alkyl group having 10 or less carbon atoms is preferable, a branched alkyl group having 5 or less carbon atoms is more preferable, and a tertiary alkyl group is particularly preferable because of excellent effects of the present invention. Specific examples include a tert-butyl group.

Specific examples of the onium salt-based acid generator (B1) include iodonium salts such as trifluoromethanesulfonate or nonafluorobutanesulfonate of bis (4-tert-butylphenyl) iodonium; trifluoromethane of tri (4-methylphenyl) sulfonium Sulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, trifluoromethane sulfonate of (4-methylphenyl) diphenylsulfonium, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, of tri (4-tert-butyl) phenylsulfonium Sulfoniu such as trifluoromethane sulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate Salt and the like.

In the present invention, it is particularly excellent that the onium salt-based acid generator (B1) contains an onium salt-based acid generator (B11) represented by the following general formula (b-2). ,preferable.

［式中、Ｒ^１４〜Ｒ^１６は、それぞれ独立に、アルキル基を表し、ｐ、ｑ、ｒは、それぞれ独立に、１〜５の整数を表し、Ｚ⁻はアニオンを表す。］

[Wherein, R ^{14 to} R ¹⁶ each independently represents an alkyl group, p, q and r each independently represent an integer of 1 to 5, and Z ⁻ represents an anion. ]

In formula (b-2), examples of the alkyl group of R ^{14 to} R ¹⁶ include the same alkyl groups as those in the above “aryl group in which at least one hydrogen atom is substituted with an alkyl group”. p, q, and r each independently represent an integer of 1 to 5, more preferably an integer of 1 to 3, and most preferably 1. The anion of Z ⁻ is not particularly limited, and may be any one that has been proposed as an anion in a known acid generator conventionally used in a chemically amplified resist composition. In the present invention, particularly from the viewpoint of resolution, Z ⁻ is preferably a fluorinated alkyl sulfonate ion in which at least one hydrogen atom of the alkyl group is substituted with a fluorine atom. It is preferably a perfluoroalkylsulfonic acid ion in which all of the hydrogen atoms of the group are substituted with fluorine atoms.

As the onium salt-based acid generator (B11), an onium salt represented by the following general formula (b-3) is particularly preferable because the amount of cation portion eluted into the immersion medium is small and the effect of the present invention is excellent. It is preferable that a system acid generator (B12) is included.

［式中、ｓは１〜１０の整数を表す。］

[Wherein, s represents an integer of 1 to 10. ]

In formula (b-3), s is preferably an integer of 1 to 8, and more preferably an integer of 1 to 4.

The onium salt-based acid generator (B1) may be used alone or in combination of two or more.

In this embodiment, the component (B) further includes an onium salt acid generator (B2) shown in the second embodiment to be described later, and known acid generators used in conventional chemically amplified resist compositions ( Hereinafter, the acid generator (B3) may be contained), but the ratio of the onium salt acid generator (B1) in the component (B) is the onium salt acid generator (B2). ) Is preferably 25 to 100% by mass of the total component (B), more preferably 50 to 100% by mass, still more preferably 80 to 100% by mass, and 100% by mass. Most preferred. When the ratio of the onium salt acid generator (B1) in the component (B) is 25% by mass or more, the effect of the present invention is sufficient. Moreover, when (B) component contains both onium salt type acid generator (B1) and onium salt type acid generator (B2), onium salt type acid generator (B1) and onium salt type acid generator The total amount of (B2) is preferably 25 to 100% by mass, more preferably 30 to 100% by mass, based on the entire component (B). At this time, the ratio of the onium salt-based acid generator (B1) to the onium salt-based acid generator (B2) is not particularly limited, but considering elution suppression into the immersion medium, it is 1: 9 to 9: 1. Is preferable, and 8: 2 to 2: 8 is more preferable.

Other acid generators (B3) include onium salt acid generators such as iodonium salts and sulfonium salts, oxime sulfonate acid generators, bisalkyl or bisarylsulfonyldiazomethanes, and poly (bissulfonyl) diazomethane. There are various known diazomethane acid generators, nitrobenzyl sulfonate acid generators, imino sulfonate acid generators, disulfone acid generators and the like.

Specific examples of the onium salt acid generator in the other acid generator (B3) include diphenyliodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, triphenylsulfonium trifluoromethanesulfonate, heptafluoropropanesulfonate, or nonafluoro thereof. Butanesulfonate, trifluoromethanesulfonate of dimethyl (4-hydroxynaphthyl) sulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate, trifluoronemethanesulfonate of monophenyldimethylsulfonium, its heptafluoropropanesulfonate, or its nonafluorobutanesulfonate, Trifluoromethane sulfone of diphenylmonomethylsulfonium Over DOO, heptafluoropropane sulfonate or nonafluorobutane sulfonate, (4-methoxyphenyl) trifluoromethanesulfonate diphenylsulfonium, its like heptafluoropropane sulfonate or nonafluorobutane sulfonates.

Specific examples of the oxime sulfonate acid generator include α- (p-toluenesulfonyloxyimino) -benzyl cyanide, α- (p-chlorobenzenesulfonyloxyimino) -benzyl cyanide, α- (4-nitrobenzenesulfonyl). Oxyimino) -benzylcyanide, α- (4-nitro-2-trifluoromethylbenzenesulfonyloxyimino) -benzylcyanide, α- (benzenesulfonyloxyimino) -4-chlorobenzylcyanide, α- (benzene Sulfonyloxyimino) -2,4-dichlorobenzylcyanide, α- (benzenesulfonyloxyimino) -2,6-dichlorobenzylcyanide, α- (benzenesulfonyloxyimino) -4-methoxybenzylcyanide, α- (2-Chlorobenzenesulfonyloxyimi ) -4-methoxybenzylcyanide, α- (benzenesulfonyloxyimino) -thien-2-ylacetonitrile, α- (4-dodecylbenzenesulfonyloxyimino) -benzylcyanide, α-[(p-toluenesulfonyloxy) Imino) -4-methoxyphenyl] acetonitrile, α-[(dodecylbenzenesulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α- (tosyloxyimino) -4-thienyl cyanide, α- (methylsulfonyloxyimino) -1 -Cyclopentenylacetonitrile, α- (methylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) -1-cycloheptenylacetonitrile, α- (methylsulfonyloxyimino) -1-cycloo Tenenyl acetonitrile, α- (trifluoromethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -cyclohexylacetonitrile, α- (ethylsulfonyloxyimino) -ethylacetonitrile, α- (propyl Sulfonyloxyimino) -propylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclopentylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclohexylacetonitrile, α- (cyclohexylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- ( Ethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (isopropylsulfonyloxyimino) -1-cycl Lopentenylacetonitrile, α- (n-butylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (ethylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (isopropylsulfonyloxyimino) -1-cyclohexenylacetonitrile , Α- (n-butylsulfonyloxyimino) -1-
Cyclohexenylacetonitrile, α- (methylsulfonyloxyimino) -phenylacetonitrile, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -phenylacetonitrile, α- (trifluoro Methylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (ethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (propylsulfonyloxyimino) -p-methylphenylacetonitrile, α- (methylsulfonyloxyimino) -P-bromophenylacetonitrile and the like. Of these, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile is preferred.

Among the diazomethane acid generators, specific examples of bisalkyl or bisarylsulfonyldiazomethanes include bis (isopropylsulfonyl) diazomethane, bis (p-toluenesulfonyl) diazomethane, bis (1,1-dimethylethylsulfonyl) diazomethane. Bis (cyclohexylsulfonyl) diazomethane, bis (2,4-dimethylphenylsulfonyl) diazomethane, and the like. Examples of poly (bissulfonyl) diazomethanes include 1,3-bis (phenylsulfonyldiazomethylsulfonyl) propane (Compound A, decomposition point 135 ° C.), 1,4-bis (phenyl) having the following structure. Sulfonyldiazomethylsulfonyl) butane (compound B, decomposition point 147 ° C.), 1,6-bis (phenylsulfonyldiazomethylsulfonyl) hexane (compound C, melting point 132 ° C., decomposition point 145 ° C.), 1,10-bis (phenyl) Sulfonyldiazomethylsulfonyl) decane (compound D, decomposition point 147 ° C.), 1,2-bis (cyclohexylsulfonyldiazomethylsulfonyl) ethane (compound E, decomposition point 149 ° C.), 1,3-bis (cyclohexylsulfonyldiazomethylsulfonyl) ) Propane (Compound F, decomposition point 153 ° C.), , 6-bis (cyclohexylsulfonyldiazomethylsulfonyl) hexane (Compound G, melting point 109 ° C., decomposition point 122 ° C.), 1,10-bis (cyclohexylsulfonyldiazomethylsulfonyl) decane (Compound H, decomposition point 116 ° C.), etc. Can be mentioned.

As another acid generator (B3), these may be used individually by 1 type, and may be used in combination of 2 or more type.

(B) 0.5-30 mass parts is preferable with respect to 100 mass parts of (A) component, and, as for content of a component, 1-10 mass parts is more preferable. If the amount is less than the above range, pattern formation may not be sufficiently performed, and if the amount exceeds the above range, a uniform solution is difficult to obtain, which may cause a decrease in storage stability.

<Component (A)> The component (A) is not particularly limited, and one or more alkali-soluble resins or resins that can be alkali-soluble have been proposed so far as base resins for chemically amplified resists. Can be used. In the former case, a so-called negative type resist composition is used, and in the latter case, a so-called positive type resist composition.

In the case of the negative type, a crosslinking agent is blended in the resist composition together with the alkali-soluble resin and the component (B). When an acid is generated from the component (B) by exposure at the time of resist pattern formation, the acid acts to cause cross-linking between the alkali-soluble resin and the cross-linking agent, thereby changing to alkali-insoluble.

As the alkali-soluble resin, a resin having a unit derived from at least one selected from α- (hydroxyalkyl) acrylic acid or a lower alkyl ester of α- (hydroxyalkyl) acrylic acid is swelled in immersion exposure. Less favorable resist patterns can be formed, which is preferable. In addition, as the cross-linking agent, for example, when an amino-based cross-linking agent that is hardly soluble in a solvent for immersion exposure such as glycoluril having a methylol group or an alkoxymethyl group, in particular, butoxymethyl group, is usually used. Can form a good resist pattern with less swelling. The blending amount of the crosslinking agent is preferably in the range of 1 to 50 parts by mass with respect to 100 parts by mass of the alkali-soluble resin.

In the case of the positive type, the component (A) is an alkali-insoluble one having a so-called acid dissociable dissolution inhibiting group, and when acid is generated from the component (B) by exposure, the acid is converted into the acid dissociable dissolution inhibiting group. (A) component becomes alkali-soluble by dissociating. Therefore, in the formation of the resist pattern, when the resist composition applied on the substrate is selectively exposed, the alkali solubility of the exposed portion increases and alkali development can be performed.

The component (A) preferably contains a structural unit derived from an (α-lower alkyl) acrylic acid ester in both positive and negative types. In the present invention, the “structural unit” means a monomer unit (monomer unit) constituting the polymer. The “(α-lower alkyl) acrylate ester” means one or both of an acrylate ester and an α-lower alkyl acrylate ester such as a methacrylic acid ester. Further, the lower alkyl group as a substituent at the α-position of “(α-lower alkyl) acrylic acid ester” is an alkyl group having 1 to 5 carbon atoms, specifically, a methyl group, an ethyl group, Examples include lower linear or branched alkyl groups such as propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, isopentyl group, and neopentyl group. The “structural unit derived from (α-lower alkyl) acrylate ester” means a structural unit formed by cleavage of an ethylenic double bond of (α-lower alkyl) acrylate ester. In the present invention, the component composition (A) preferably contains 20 mol% or more, more preferably 50 mol% or more of a structural unit derived from (α-lower alkyl) acrylic acid ester. It is desirable because it is obtained.

Structural Unit (a1) When the resist composition of the present invention is positive, the component (A) is a structural unit derived from an (α-lower alkyl) acrylate ester having an acid dissociable, dissolution inhibiting group (a1). It is preferable to have. The acid dissociable, dissolution inhibiting group in the structural unit (a1) has an alkali dissolution inhibiting property that makes the entire component (A) insoluble in alkali before exposure, and is dissociated by the action of an acid generated from the component (B) after exposure. And if it changes this whole (A) component to alkali solubility, it can use without limitation in particular. In general, a group that forms a cyclic or chain tertiary alkyl ester, a tertiary alkoxycarbonyl group, or a chain alkoxyalkyl group is widely known with a carboxyl group of (meth) acrylic acid. . “(Meth) acrylic acid ester” means one or both of acrylic acid ester and methacrylic acid ester.

As the acid dissociable inhibitory group in the structural unit (a1), for example, an acid dissociable, dissolution inhibiting group containing an aliphatic cyclic group can be preferably used. The term “aliphatic” in the present invention is a relative concept with respect to aromatics, and is defined to mean groups, compounds, etc. that do not have aromaticity. The “aliphatic cyclic group” means a monocyclic group or a polycyclic group (alicyclic group) having no aromaticity, and the “aliphatic cyclic group” means carbon and Although it is not limited to being a group consisting of hydrogen (hydrocarbon group), it is preferably a hydrocarbon group. The “hydrocarbon group” may be either saturated or unsaturated, but is usually preferably saturated. A polycyclic group (alicyclic group) is preferred. Specific examples of such aliphatic cyclic groups include, for example, monocycloalkanes, bicycloalkanes, tricycloalkanes, tera-ra which may or may not be substituted with a fluorine atom or a fluorinated alkyl group. Examples thereof include a group in which one hydrogen atom is removed from cycloalkane or the like. Specific examples include monocycloalkanes such as cyclopentane and cyclohexane, and groups obtained by removing one hydrogen atom from polycycloalkanes such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Such monocyclic or polycyclic groups can be appropriately selected and used from among many proposed ArF resists. Among these, a cyclopentyl group, a cyclohexyl group, an adamantyl group, a norbornyl group, and a tetracyclododecanyl group are preferable from an industrial viewpoint, and an adamantyl group is particularly preferable.

More specifically, examples of the structural unit (a1) include structural units represented by general formulas (a1-1) to (a1-9) shown below.

（式中、Ｒは水素原子またはα−低級アルキル基、Ｒ^１は低級アルキル基である。）

(In the formula, R is a hydrogen atom or an α-lower alkyl group, and R ¹ is a lower alkyl group.)

（式中、Ｒは水素原子またはα−低級アルキル基、Ｒ^２およびＲ^３はそれぞれ独立して低級アルキル基である。）

(In the formula, R is a hydrogen atom or an α-lower alkyl group, and R ² and R ³ are each independently a lower alkyl group.)

（式中、Ｒは水素原子またはα−低級アルキル基、Ｒ^４は第３級アルキル基である。）

(In the formula, R is a hydrogen atom or an α-lower alkyl group, and R ⁴ is a tertiary alkyl group.)

（式中、Ｒは水素原子またはα−低級アルキル基である。）

(In the formula, R is a hydrogen atom or an α-lower alkyl group.)

（式中、Ｒは水素原子またはα−低級アルキル基、Ｒ^５はメチル基である。）

(In the formula, R is a hydrogen atom or an α-lower alkyl group, and R ⁵ is a methyl group.)

（式中、Ｒは水素原子またはα−低級アルキル基、Ｒ^６は低級アルキル基である。）

(In the formula, R is a hydrogen atom or an α-lower alkyl group, and R ⁶ is a lower alkyl group.)

（式中、Ｒは水素原子またはα−低級アルキル基である。）

(In the formula, R is a hydrogen atom or an α-lower alkyl group.)

（式中、Ｒは水素原子またはα−低級アルキル基である。）

(In the formula, R is a hydrogen atom or an α-lower alkyl group.)

（式中、Ｒは水素原子またはα−低級アルキル基、Ｒ^７は低級アルキル基である。）

(In the formula, R is a hydrogen atom or an α-lower alkyl group, and R ⁷ is a lower alkyl group.)

Each of R ^{1 to} R ³ and R ^{6 to} R ⁷ is preferably a lower linear or branched alkyl group having 1 to 5 carbon atoms, and includes a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, Examples include isobutyl group, tert-butyl group, pentyl group, isopentyl group, neopentyl group and the like. Industrially, a methyl group or an ethyl group is preferable. R ⁴ is a tertiary alkyl group such as a tert-butyl group or a tert-amyl group, and the case where it is a tert-butyl group is industrially preferable.

Among the structural units (a1) mentioned above, the structural units represented by the general formulas (a1-1), (a1-2), (a1-3), and (a1-6) are particularly immersion lithography. It is more preferable because a pattern having excellent resistance to dissolution in the solvent used in the step and excellent resolution can be formed.

As the structural unit (a1), one type may be used alone, or two or more types may be used in combination. (A) As for the ratio of the structural unit (a1) in a component, 5-60 mol% is preferable with respect to the sum total of all the structural units of (A) component, and 5-50 mol% is more preferable. By setting it to the lower limit value or more, a pattern can be obtained when the resist composition is used, and by setting it to the upper limit value or less, it is possible to balance with other structural units.

Structural Unit (a2) The component (A) is a structural unit derived from an (α-lower alkyl) acrylate ester having a lactone-containing monocyclic or polycyclic group in addition to the structural unit (a1) (a2). ). The lactone-containing monocyclic or polycyclic group of the structural unit (a2) can improve adhesion of the resist film to the substrate or can be hydrophilic with a developer when the component (A) is used for forming a photoresist film. It is effective in improving the sex. In addition, lactone here shows one ring containing -O-C (O)-structure, and this is counted as one ring. Therefore, when it has only a 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.

As the structural unit (a2), any structural unit can be used without particular limitation as long as it has both such a lactone structure (—O—C (O) —) and a cyclic group. Specifically, examples of the lactone-containing monocyclic group include groups obtained by removing one hydrogen atom from γ-butyrolactone, and examples of the lactone-containing polycyclic group include bicycloalkanes having a lactone ring, tricyclo Examples include groups in which one hydrogen atom has been removed from an alkane or tetracycloalkane. In particular, a group obtained by removing one hydrogen atom from a lactone-containing tricycloalkane having the following structural formula (IV) or structural formula (V) is advantageous in that it is easily available in the industry.

Examples of the structural unit (a2) include a structural unit derived from an acrylate ester containing a lactone-containing monocycloalkyl group or a tricycloalkyl group (α-lower alkyl group). More specifically, examples of the structural unit (a2) include structural units represented by general formulas (a2-1) to (a2-5) shown below.

（式中、Ｒ’は水素原子または低級アルキル基である。）

(In the formula, R ′ is a hydrogen atom or a lower alkyl group.)

（式中、Ｒ’は水素原子または低級アルキル基である。） この構成単位は、結合位置が５位又は６位の異性体の混合物として存在する。

(In the formula, R ′ is a hydrogen atom or a lower alkyl group.) This structural unit exists as a mixture of isomers at the 5-position or 6-position.

（式中、Ｒ’は水素原子または低級アルキル基であり、Ｒ^８、Ｒ^９は、それぞれ独立に、水素原子または低級アルキル基である。）

(In the formula, R ′ is a hydrogen atom or a lower alkyl group, and R ⁸ and R ⁹ are each independently a hydrogen atom or a lower alkyl group.)

（式中、Ｒ’は水素原子または低級アルキル基であり、ｏは０または１である。）

(In the formula, R ′ is a hydrogen atom or a lower alkyl group, and o is 0 or 1.)

（式中、Ｒ’は水素原子または低級アルキル基である）

(Wherein R ′ is a hydrogen atom or a lower alkyl group)

In general formulas (a2-1) to (a2-5), the lower alkyl group for R ′ is the same as the lower alkyl group for R in the structural unit (a1). In general formula (a2-3), R ⁸ and R ⁹ are each independently a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms, and in view of industrial availability, etc., a hydrogen atom Is preferred.

Among the structural units represented by the general formulas (a2-1) to (a2-5), when used in a resist composition, the effect of suppressing and reducing the proximity effect is excellent. Γ-butyrolactone ester of (α-lower alkyl) acrylic acid represented by formula (a2-3) having an ester bond at the α carbon on the lactone skeleton, ie, (α-lower alkyl) acrylic of γ-butyrolactone A structural unit derived from an acid ester is preferred. Further, a configuration derived from a norbornane lactone ester of (α-lower alkyl) acrylic acid represented by general formulas (a2-1) and (a2-2), that is, a (α-lower alkyl) acrylate ester of norbornane lactone. The unit is preferable because the shape of a resist pattern obtained when used in a resist composition, for example, rectangularity is even better. In particular, the structural unit represented by the general formula (a2-2) is preferable because of its extremely high effect. Among these, the structural unit represented by general formula (a2-3) is most preferable.

In the component (A), as the structural unit (a2), only one type may be used, or two or more types different from each other may be used in combination. It is preferable to introduce two or more different lactone skeletons into the skeleton of the component (A) because the adhesion of the photoresist film to the substrate, the affinity with an alkali developer, and the etching resistance are further improved.

5-80 mol% is preferable with respect to the sum total of all the structural units which comprise (A) component, and, as for the ratio of structural unit (a2), 5-60 mol% is more preferable. By setting it to the lower limit value or more, the effect of containing the structural unit (a2) is sufficiently obtained, and by setting the upper limit value or less, it is possible to balance with other structural units.

Structural Unit (a3) The component (A) contains a polar group-containing aliphatic hydrocarbon group in addition to the structural unit (a1) or in addition to the structural units (a1) and (a2) ( It is preferable to have a structural unit derived from (α-lower alkyl) acrylate ester. By having the structural unit (a3), the hydrophilicity of the component (A) is increased, the affinity with the developer is increased, the alkali solubility in the exposed area is improved, and the resolution is improved. Examples of the polar group include a hydroxyl group and a cyano group, and a hydroxyl group is particularly preferable. Examples of the aliphatic hydrocarbon group include a linear or branched hydrocarbon group (alkylene group) having 1 to 10 carbon atoms and a polycyclic aliphatic hydrocarbon group (polycyclic group). As the polycyclic group, for example, a resin for a resist composition for ArF excimer laser can be appropriately selected from among many proposed ones. Among these, a structural unit containing a hydroxyl group, a cyano group or a carboxyl group-containing aliphatic polycyclic group and derived from a (meth) acrylic acid ester is more preferable. Examples of the polycyclic group include groups in which one or more hydrogen atoms have been removed from bicycloalkane, tricycloalkane, tetracycloalkane, or the like. Specific examples include groups in which one or more hydrogen atoms have been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane. Such a polycyclic group can be appropriately selected and used from among many proposed polymers (resin components) for resist compositions for ArF excimer lasers. Among these polycyclic groups, an adamantyl group, a norbornyl group, and a tetracyclododecanyl group are industrially preferable.

As the structural unit (a3), when the hydrocarbon group in the polar group-containing aliphatic hydrocarbon group is a linear or branched hydrocarbon group having 1 to 10 carbon atoms, (α-lower alkyl) acrylic acid A structural unit derived from hydroxyethyl ester is preferable, and when the hydrocarbon group is a polycyclic group, structural units represented by the following formulas (a3-1) and (a3-2) are preferable. .

（式中、Ｒ’は前記に同じであり、ｎは１〜３の整数である。）

(In the formula, R ′ is the same as above, and n is an integer of 1 to 3).

Among these, those in which n is 1 and the hydroxyl group is bonded to the 3-position of the adamantyl group are preferable.

（式中、Ｒ’は前記に同じであり、ｋは１〜３の整数である。）

(In the formula, R ′ is the same as described above, and k is an integer of 1 to 3).

Among these, those in which k is 1 are preferable. These exist as a mixture of isomers (a mixture of compounds in which the cyano group is bonded to the 4-position or 5-position of the norbornanyl group).

The structural unit (a3) is not an essential component of the component (A). However, when the structural unit (a3) is contained in the component (A), it is 5 to 50 mol based on the total of all the structural units constituting the component (A). %, Preferably 10 to 40 mol%. By setting it to the lower limit value or more, the effect of improving LER (line edge roughness) is improved, and when the upper limit value is exceeded, the resist pattern shape may be deteriorated due to the balance of other structural units.

-Structural unit (a4) The component (A) is another structural unit (a4) not classified into the above structural units (a1) to (a3), that is, acid dissociable dissolution inhibition, as long as the effects of the present invention are not impaired. It may have a structural unit that does not contain a group, a lactone functional group, or a polar group. As the structural unit (a4), for example, a structural unit containing an acid non-dissociable aliphatic polycyclic group and derived from an (α-lower alkyl) acrylate ester is preferable. When such a structural unit is used, when used for a positive resist composition, a solution from an isolated pattern to a semi-dense pattern (a line and space pattern having a space width of 1.2 to 2 with respect to a line width of 1) is obtained. It is excellent in image properties and is preferable.

Examples of the polycyclic group include those similar to those exemplified in the case of the structural unit (a3), and are appropriately selected from a number of conventionally known ArF positive resist materials. Can be used. In particular, at least one selected from a tricyclodecanyl group, an adamantyl group, a tetracyclododecanyl group, and an isobornyl group is preferable in terms of industrial availability. In particular, the following general formulas (a4-1) to (a4-3) are preferable.

（式中、Ｒ’は前記と同じである。）

(In the formula, R ′ is the same as described above.)

（式中、Ｒ’は前記と同じである。）

(In the formula, R ′ is the same as described above.)

（式中、Ｒ’は前記と同じである。）

(In the formula, R ′ is the same as described above.)

The structural unit (a4) is not an essential component of the component (A). However, when the structural unit (a4) is contained in the component (A), the structural unit is based on the total of all the structural units constituting the component (A). When (a4) is contained in an amount of 1 to 30 mol%, preferably 10 to 20 mol%, it is preferable because an excellent improvement effect can be obtained in the resolution of a semi-dense pattern from an isolated pattern.

Component (A) is easily produced by copolymerizing monomers corresponding to the respective structural units by known radical polymerization using a radical polymerization initiator such as azobisisobutyronitrile (AIBN). I can do it.

Further, the mass average molecular weight of the component (A) (polystyrene equivalent, the same applies hereinafter) is not particularly limited, but is preferably 2000 to 30000, more preferably 2000 to 20000 in the case of a negative type, and further 4000 to 15000. Preferably, in the case of a positive type, 5000 to 30000 is more preferable, and 8000 to 20000 is more preferable. If it is larger than this range, the solubility in a resist solvent is deteriorated, and if it is smaller, the dry etching resistance and the resist pattern cross-sectional shape may be deteriorated.

<(C) Component> The resist composition of this embodiment comprises an organic solvent containing the resin component or the component (A), the component (B), and any component (D) and / or (E) described below. It can be produced by dissolving in (C) (hereinafter sometimes referred to as component (C)). As the component (C), any component can be used as long as it can dissolve each component to be used to form a uniform solution, and any one of conventionally known solvents for chemically amplified resists can be used. Two or more types can be appropriately selected and used. For example, ketones such as γ-butyrolactone, acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, 2-heptanone (HP), ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, propylene glycol monoacetate, Polypropylene and its derivatives such as dipropylene glycol or monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether of dipropylene glycol monoacetate, cyclic ethers such as dioxane, lactic acid Methyl, ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, Methyl Tokishipuropion acid, esters such as ethyl ethoxypropionate can be exemplified. Among these, HP or EL, or a mixture thereof is preferable because there is little elution into the immersion medium in the immersion lithography process.

A mixed solvent obtained by mixing propylene glycol monomethyl ether acetate (PGMEA) and a polar solvent is preferable. The blending ratio (mass ratio) may be appropriately determined in consideration of the compatibility between PGMEA and the polar solvent, preferably 9: 1 to 1: 9, more preferably 8: 2 to 2: 8. It is preferable to be within the range. More specifically, when EL is blended as a polar solvent, the mass ratio of PGMEA: EL is preferably 8: 2 to 2: 8, more preferably 7: 3 to 3: 7. In addition, as the organic solvent, a mixed solvent of at least one selected from PGMEA and EL and γ-butyrolactone is also preferable. In this case, the mixing ratio of the former and the latter is preferably 70:30 to 95: 5.

The amount of the component (C) used is not particularly limited, and is a concentration that can be applied to a support such as a substrate, and is appropriately set according to the coating film thickness. It is used so that the partial concentration is in the range of 2 to 20% by mass, preferably 5 to 15% by mass.

<Component (D)> In the positive resist composition of the present invention, a nitrogen-containing organic compound (D) (hereinafter, referred to as “optional”) is further included as an optional component in order to improve the resist pattern shape, the stability over time. (Referred to as component (D)). Since a wide variety of components (D) have already been proposed, any known one may be used, but amines, particularly secondary lower aliphatic amines and tertiary lower aliphatic amines are preferred. . Here, the lower aliphatic amine refers to an alkyl or alkyl alcohol amine having 12 or less carbon atoms, and examples of the secondary or tertiary amine include trimethylamine, diethylamine, triethylamine, di-n-propylamine, Examples include tri-n-propylamine, tri-n-pentylamine, tri-n-dodecylamine, tri-n-octylamine, diethanolamine, triethanolamine, and triisopropanol. In particular, an aliphatic tertiary amine having an alkyl group having 5 to 12 carbon atoms is preferable, and tri-n-octylamine is particularly preferable. Moreover, the nitrogen-containing organic compound represented by the following general formula (VI) can also be used preferably.

（式中、Ｒ^１１、Ｒ^１２は、それぞれ独立して低級アルキレン基、Ｒ^１３は低級アルキル基を示す。）

(In the formula, R ¹¹ and R ¹² each independently represent a lower alkylene group, and R ¹³ represents a lower alkyl group.)

R ¹¹ , R ¹² and R ¹³ may be linear, branched or cyclic, but are preferably linear or branched. R ¹¹ , R ¹² and R ¹³ each have 1 to 5 carbon atoms, preferably 1 to 3 carbon atoms, from the viewpoint of molecular weight adjustment. The carbon numbers of R ¹¹ , R ¹² and R ¹³ may be the same or different. The structures of R ¹¹ and R ¹² may be the same or different. Examples of the compound represented by the general formula (VI) include tris- (2-methoxymethoxyethyl) amine, tris-2- (2-methoxy (ethoxy)) ethylamine, and tris- (2- (2-methoxyethoxy). Methoxyethyl) amine and the like. Of these, tris-2- (2-methoxy (ethoxy)) ethylamine is preferable. Among these (D) components, the compound represented by the general formula (VI) is particularly preferable, and tris-2- (2-methoxy (ethoxy)) ethylamine is particularly preferable because of its low solubility in the immersion medium. . These may be used alone or in combination of two or more. These (D) components are normally used in 0.01-5.0 mass% with respect to (A) component.

<Component (E)> Further, for the purpose of preventing the sensitivity deterioration due to the blending of the component (D) and improving the resist pattern shape, the stability of holding, etc., an organic carboxylic acid or phosphorus oxo is further added as an optional component. An acid or a derivative thereof (E) (hereinafter referred to as “component (E)”) can be contained. In addition, (D) component and (E) component can also be used together, and any 1 type can also be used. As the organic carboxylic acid, for example, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid and the like are suitable. Phosphorus oxoacids or derivatives thereof include phosphoric acid, phosphoric acid di-n-butyl ester, phosphoric acid diphenyl ester and other phosphoric acid or derivatives thereof such as phosphonic acid, phosphonic acid dimethyl ester, phosphonic acid- Like phosphonic acids such as di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, phosphonic acid dibenzyl ester and derivatives thereof, phosphinic acids such as phosphinic acid, phenylphosphinic acid and their esters Among these, phosphonic acid is particularly preferable. (E) A component is used in the ratio of 0.01-5.0 mass parts per 100 mass parts of (A) component.

<Other Optional Components> In the positive resist composition of the present invention, if desired, there are further miscible additives such as an additional resin for improving the performance of the resist film, and an interface for improving the coating property. An activator, a dissolution inhibitor, a plasticizer, a stabilizer, a colorant, an antihalation agent, and the like can be appropriately added and contained.

In the production of the resist composition of the present invention, in order to dissolve the component (A) and the component (B) and other optional components in the component (C), for example, the above-described components are mixed by a usual method, It is only necessary to stir, and if necessary, it may be dispersed and mixed using a disperser such as a dissolver, a homogenizer, or a three roll mill. Moreover, after mixing, you may further filter using a mesh, a membrane filter, etc.

<< Resist Composition of Second Aspect >> The resist composition according to the second aspect of the present invention is such that the component (B) contains an onium salt acid generator (B2) having a cyclic group-containing anion. Except for the characteristics, the resist composition is the same as that of the first aspect.

Here, “having a cyclic group-containing anion” means that the anion of the onium salt acid generator contains a cyclic group in its structure. The cyclic group may be monocyclic or polycyclic, and is preferably a 3- to 20-membered ring (the number of atoms constituting the basic ring excluding the substituent is 3 to 20) from the viewpoint of the effects of the present invention. A ˜15-membered ring is more preferred, and a 5- to 12-membered ring is most preferred. The basic ring may be a heterocyclic group containing a hetero atom such as an oxygen atom, a nitrogen atom or a sulfur atom, or may be a hydrocarbon group consisting of only a carbon atom and a hydrogen atom. The basic ring may have a sulfonyl group (—SO ₂ —), a carboxy group (—CO—), or the like. The hydrocarbon group may be aliphatic or aromatic, and is more preferably aliphatic. As the aliphatic hydrocarbon group, for example, a monocyclic or polycyclic aliphatic hydrocarbon group conventionally known as an ArF positive resist material can be used, one from a monocycloalkane such as cyclohexane or cyclopentane. Or a monocyclic group such as a group in which two hydrogen atoms are removed; a polycyclic alkane such as a group in which one or two hydrogen atoms are removed from a polycycloalkane such as bicycloalkane, tricycloalkane, or tetracycloalkane. Specific examples include groups in which one or two hydrogen atoms have been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, or tetracyclododecane. In addition, a substituent having no charge, such as an alkyl group, may be bonded to the basic ring, but for the effects of the present invention, the shorter the substituent length, the more preferable, for example, alkyl As the carbon number of the group is smaller, for example, the number of carbon atoms is preferably 5 or less, and most preferably has no substituent.

The cyclic group-containing anion may have a negatively charged group or atom (for example, —N ⁻ —) on the basic ring of these cyclic groups. In addition, a group having a negative charge (for example, —SO ₃ ^— ) or an atom may be bonded.

In this embodiment, it is preferable that the onium salt-based acid generator (B2) contains a compound (B21) represented by the following general formula (b-4) because the effects of the present invention are excellent.

［式中、Ｘは、少なくとも１つの水素原子がフッ素原子で置換された炭素数２〜６のアルキレン基を表し；Ｒ^２１〜Ｒ^２３は、それぞれ独立に、アリール基またはアルキル基を表し、Ｒ^２１〜Ｒ^２３のうち少なくとも１つはアリール基を表す］

[Wherein, X represents an alkylene group having 2 to 6 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom; R ^{21 to} R ²³ each independently represents an aryl group or an alkyl group; ^At least one of ^{21 to} R ²³ represents an aryl group]

In formula (b-4), X represents a linear or branched alkylene group in which at least one hydrogen atom is substituted with a fluorine atom, and the alkylene group preferably has 2 to 6 carbon atoms. , More preferably 3-5, most preferably 3. The smaller the carbon number of the alkylene group of X, the better the solubility in the resist solvent, which is preferable. Further, in the alkylene group of X, the larger the number of hydrogen atoms substituted by fluorine atoms, the stronger the acid strength and the better the transparency to high energy light of 200 nm or less and electron beam. The proportion of fluorine atoms in the alkylene group, that is, the fluorination rate, is preferably 70 to 100%, more preferably 90 to 100%, and most preferably 100%, that is, all hydrogen atoms are replaced with fluorine atoms. Perfluoroalkylene group.

R ^{21 to} R ²³ each independently represents an aryl group or an alkyl group. ^Further, among R 21 ^{to R 23,} at least one group represents an aryl group. Of R ^{21 to} R ²³ , two or more are preferably aryl groups, and most preferably R ^{21 to} R ²³ are all aryl groups. The aryl group of R ²¹ to R ^23, not particularly limited, for example, an aryl group having 6 to 20 carbon atoms, an alkyl group, a phenyl group which may not be substituted with a halogen atom or the like And a naphthyl group. An aryl group having 6 to 10 carbon atoms is preferable because it can be synthesized at low cost. The alkyl group of R ²¹ to R ^23, not particularly limited, for example, a straight, include alkyl groups such as branched or cyclic. It is preferable that it is C1-C5 from the point which is excellent in resolution. Specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an n-pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a nonyl group, and a decanyl group. A methyl group is preferable because it is excellent in resolution and can be synthesized at low cost. Among these, it is most preferable that all of R ^{21 to} R ²³ are phenyl groups. A compound (B21) may be used independently and may be used in combination of 2 or more type.

Moreover, in this aspect, it is preferable that the compound (B22) represented by the following general formula (b-5) is included as the onium salt acid generator (B2) because the effects of the present invention are excellent.

［式中、Ｙは環式基を表し；Ｒ^２４〜Ｒ^２６は、それぞれ独立に、アリール基またはアルキル基を表し、Ｒ^２４〜Ｒ^２６のうち少なくとも１つはアリール基を表す］

[Wherein Y represents a cyclic group; R ^{24 to} R ²⁶ each independently represents an aryl group or an alkyl group, and at least one of R ^{24 to} R ²⁶ represents an aryl group]

In formula (b-5), Y represents a cyclic group, and examples of the cyclic group include the same groups as described above. In particular, Y is preferably an aliphatic hydrocarbon group from the viewpoint of excellent effects of the present invention, and particularly preferably Y is an adamantyl group. R ^{24 to} R ²⁶ are the same as R ^{21 to} R ²³ in the above formula (b-4). A compound (B22) may be used independently and may be used in combination of 2 or more type.

In this embodiment, the onium salt-based acid generator (B2) preferably contains one or both of the above-mentioned compounds (B21) and (B22). In the onium salt acid generator (B2), the total amount of the compounds (B21) and (B22) is preferably 50 to 100% by mass, more preferably 80 to 100% by mass of the onium salt acid generator (B2). Most preferably, the onium salt-based acid generator (B2) is preferably composed only of the compound (B21) and / or (B22). When the compounds (B21) and (B22) are used in combination, the ratio of the compounds (B21) and (B22) is preferably 1: 9 to 9: 1, and more preferably 2: 8 to 8: 2.

In this embodiment, the component (B) further includes an onium salt-based acid generator (B1) shown in the first embodiment described above, or a known acid generator (conventional acid generator used in conventional chemically amplified resist compositions). Other acid generators (B3)) may be contained, but the ratio of the onium salt acid generator (B2) in the component (B) does not include the onium salt acid generator (B1). It is preferable that it is 25-100 mass% of the whole (B) component, and 30-100 mass% is more preferable. When the ratio of the onium salt acid generator (B1) in the component (B) is 25% by mass or more, the effect of the present invention is sufficient. Further, when the component (B) contains both the onium salt acid generator (B1) and the onium salt acid generator (B2), the onium salt acid generator (B1) in the component (B) The total amount of the onium salt acid generator (B2) and the ratio of the onium salt acid generator (B1) to the onium salt acid generator (B2) are the same as described in the first embodiment. is there.

(B) Content of a component is the same as having described in the 1st aspect.

<< Resist Pattern Forming Method >> Next, a resist pattern forming method according to the present invention will be described. First, a resist composition according to the present invention is applied on a substrate such as a silicon wafer by a spinner or the like, and then pre-baked (PAB treatment). Note that a two-layer laminate in which an organic or inorganic antireflection film is provided between the substrate and the coating layer of the resist composition may be used. Moreover, it can also be set as the 2 layer laminated body which provided the organic type anti-reflective film on the application layer of the resist composition, and also can be set as the 3 layer laminated body which provided the antireflection film of the lower layer on this. The steps so far can be performed using a known method. The operating conditions and the like are preferably set as appropriate according to the composition and characteristics of the resist composition to be used.

Next, the resist layer, which is a coating film of the resist composition obtained above, is selectively subjected to immersion exposure (Liquid Immersion Lithography) through a desired mask pattern. At this time, the space between the resist layer and the lowermost lens of the exposure apparatus is previously filled with a solvent having a refractive index larger than the refractive index of air, but is further larger than the refractive index of air and the resist layer has It is preferable to perform exposure in a state filled with a solvent having a refractive index smaller than the refractive index. The wavelength used for exposure is not particularly limited, and radiation such as ArF excimer laser, KrF excimer laser, F ₂ laser, EUV (extreme ultraviolet), VUV (vacuum ultraviolet), electron beam, X-ray, soft X-ray is used. It can be carried out. The resist composition according to the present invention is effective for a KrF or ArF excimer laser, particularly an ArF excimer laser.

As described above, in the resist pattern forming method of the present invention, it is preferable that the resist layer and the lens at the lowest position of the exposure apparatus are filled with a solvent larger than the refractive index of air during exposure. Examples of the solvent having a refractive index larger than that of air include water and a fluorine-based inert liquid.

Specific examples of the fluorine-based inert liquid include fluorine-based compounds such as C ₃ HCl ₂ F ₅ , C ₄ F ₉ OCH ₃ , C ₄ F ₉ OC ₂ H ₅ , and C ₅ H ₃ F ₇ as a main component. And a liquid having a boiling point of preferably 70 to 180 ° C., more preferably 80 to 160 ° C., such as a liquid or a perfluoroalkyl compound. Specific examples of the perfluoroalkyl compound include a perfluoroalkyl ether compound and a perfluoroalkylamine compound. More specifically, examples of the perfluoroalkyl ether compound include perfluoro (2-butyl-tetrahydrofuran) (boiling point: 102 ° C.). Examples of the perfluoroalkylamine compound include perfluorotributylamine ( Boiling point of 174 ° C.). Among the fluorine-based inert liquids, those having a boiling point in the above range are preferable because removal of the immersion medium after completion of exposure can be performed by a simple method.

In the present invention, the immersion medium is preferably water because the resist composition of the present invention is particularly resistant to adverse effects on water and is excellent in sensitivity and resist pattern profile shape. Water is also preferable from the viewpoints of cost, safety, environmental problems, and versatility.

Next, after the exposure process is completed, PEB (post-exposure heating) is performed, and subsequently, development processing is performed using an alkaline developer composed of an alkaline aqueous solution. And preferably, water rinsing is performed using pure water. In the water rinse, for example, water is dropped or sprayed on the surface of the substrate while rotating the substrate to wash away the developer on the substrate and the resist composition dissolved by the developer. And the resist pattern by which the coating film of the resist composition was patterned by the shape according to the mask pattern by drying is obtained.

In the resist composition and the resist pattern forming method of the present invention, since the elution amount of the component (B) into the immersion medium is small, substance elution into the immersion medium used in the immersion lithography process can be reduced. . Thus, contamination of the immersion medium is reduced, thereby reducing changes in the properties of the immersion medium, for example local changes in the refractive index. Further, contamination of the lens of the exposure apparatus is reduced. Furthermore, since the elution of the component (B) is reduced and the change in the resist composition is reduced, it is presumed that the change in the performance of the resist layer is also suppressed. For this reason, it is expected that the resolution, shape and the like of the formed resist pattern can be suppressed. Further, since contamination of the immersion medium and the lens of the exposure apparatus is reduced, it is not necessary to take protective measures against these, and it is expected to contribute to simplification of the process and the exposure apparatus.

Examples of the present invention will be described below, but the scope of the present invention is not limited to these examples. In addition, the structure of the (B) component used in the following Example and comparative example and its symbol are shown below.

Example 1 A positive resist composition 1 was prepared by uniformly dissolving the following component (A), component (B), and component (D) in component (C). As the component (A), 100 parts by mass of a methacrylic acid ester / acrylic acid ester copolymer composed of three structural units represented by the following formula (1) was used. (A) Ratio of each structural unit p, q, and r used for preparation of component was p = 50 mol%, q = 30 mol%, and r = 20 mol%. The prepared component (A) had a mass average molecular weight of 10,000.

As component (B), 11.7 parts by mass of TTBPS-PFBS was used. As component (C), 1250 parts by mass of propylene glycol monomethyl ether acetate (hereinafter abbreviated as “PM”) was used. As component (D), 1.0 part by mass of tri-n-octylamine was used.

Next, a resist pattern was formed using the positive resist composition 1 obtained above. First, the positive resist composition 1 is applied onto a silicon wafer having a diameter of 8 inches using a spinner, prebaked on a hot plate at 130 ° C. for 90 seconds, and dried to form a resist layer having a thickness of 200 nm. Formed.

On the resist layer thus formed, an in-circle extraction tool having a diameter of 130 mm was provided, and then 30 mL of 23 ° C. pure water was dropped and left at room temperature for 5 minutes. Next, the pure water was analyzed by CE / MS (capillary electrophoresis / mass spectrometer) (G1600A manufactured by Agilent Technologies / 1100 series LC / MSD SL G1946D manufactured by Agilent Technologies) and the cation part (PAG +) of component (B) ) Was measured, and the amount of elution (mol / cm ² ) per square centimeter of the resist layer before exposure was determined. The results are shown in Table 1.

Further, a resist layer is formed in the same manner as described above, and an open frame exposure (30 mJ / cm ² ) with an ArF excimer laser (193 nm) using a simple exposure apparatus VUVES4500 (manufactured by RISOTEC Japan Co., Ltd.) Exposure without passing through a mask). Next, after providing an in-circle extraction tool having a diameter of 130 mm on the exposed resist layer, 30 mL of 23 ° C. pure water was dropped and left at room temperature for 5 minutes. The pure water was analyzed by CE / MS (capillary electrophoresis / mass spectrometer) (G1600A manufactured by Agilent Technologies 1100 series LC / MSD SL G1946D manufactured by Agilent Technologies) and the cation part (PAG +) of component (B) The density was measured, and the amount of elution (mol / cm ² ) per square centimeter of the resist layer after exposure was determined. The results are shown in Table 1.

Comparative Example 1 A positive resist composition was prepared in the same manner as in Example 1 except that 9.0 parts by mass of TPS-PFBS was used as the component (B) in Example 1, and the same evaluation was performed. . The results are shown in Table 1.

[Example 2] A positive resist composition was prepared in the same manner as in Example 1 except that 8.4 parts by mass of TPS-IMIDO was used as the component (B) in Example 1, and the cation part of the component (B). (PAG +) and anion (PAG-) each concentration was measured, except that the resist layer elution amount per square centimeter after exposure (molar / cm ²⁾ was determined and evaluated in the same manner as in example 1 . The results are shown in Table 2.

[Example 3] In Example 1, 7.7 parts by mass of TPS-Ad was used as the component (B), and ethyl lactate (hereinafter abbreviated as “EL”) as the component (C): PM = 4: 6 ( A positive resist composition was prepared in the same manner as in Example 1 except that 1250 parts by mass of the mixed solvent of (mass ratio) was used, and the respective concentrations of the cation part (PAG +) and the anion part (PAG-) of the component (B) And the same evaluation as in Example 1 was performed except that the elution amount (mol / cm ² ) per square centimeter of the resist layer after exposure was determined. The results are shown in Table 2.

[Comparative Example 2] A positive resist composition was prepared in the same manner as in Example 1 except that 6.6 parts by mass of TPS-PFMS was used as the component (B) in Example 1, and the cation of the component (B) The same evaluation as in Example 1 was performed, except that the concentration of each part (PAG +) and anion part (PAG-) was measured, and the amount of elution (mol / cm ² ) per square centimeter of the resist layer after exposure was determined. It was. The results are shown in Table 2.

Comparative Example 3 A positive resist composition was prepared in the same manner as in Example 1 except that 12.2 parts by mass of TPS-PFOS was used as the component (B) in Example 1, and the cation of the component (B) The same evaluation as in Example 1 was performed, except that the concentration of each part (PAG +) and anion part (PAG-) was measured, and the amount of elution (mol / cm ² ) per square centimeter of the resist layer after exposure was determined. It was. The results are shown in Table 2.

[Comparative Example 4] A positive resist composition was prepared in the same manner as in Example 1 except that 9.0 parts by mass of TPS-PFBS was used as the component (B) in Example 1. The same evaluation as in Example 1 was performed, except that the concentration of each part (PAG +) and anion part (PAG-) was measured, and the amount of elution (mol / cm ² ) per square centimeter of the resist layer after exposure was determined. It was. The results are shown in Table 2.

As is clear from the above results, in the resist composition of Example 1 using TTBPS-PFBS corresponding to the onium salt acid generator (B1), the cation portion ( Elution of (PAG +) was hardly observed. Further, in the resist compositions of Examples 2 and 3 using TPS-IMIDO and TPS-Ad corresponding to the onium salt acid generator (B2), both the cation part (PAG +) and the anion part (PAG-) In addition, the amount of elution was small both before and after exposure. On the other hand, in the resist compositions of Comparative Examples 2 to 4, both the cation part (PAG +) and the anion part (PAG-) were eluted. Further, when Examples 2 and 3 and Comparative Examples 2 to 4 are compared, the resist compositions of Examples 2 and 3 are the same before the exposure, although the structure of the cation part (PAG +) is the same. The elution amount of the cation part (PAG +) was small. In the above examples and comparative examples, the amount of elution before exposure is for evaluating the amount of elution in an unexposed portion when a resist pattern is formed by performing selective exposure, and the amount of elution after exposure is This is for evaluating the amount of elution in the exposed area. Therefore, in Examples 1 to 3, the resist composition of Examples 1 to 3 because the elution amount of the component (C) was small with respect to the immersion medium (water) both before and after exposure. However, it can be clearly used for a resist pattern forming method including a step of immersion exposure.

  The structure of the component (B) and its abbreviations used in Example 4 and Comparative Example 5 below are shown below.

[Example 4]
In Example 1, 3.5 parts by mass of TPS-IMIDO as component (B), 0.6 parts by mass of tri-n-octylamine as component (D), PGMEA and propylene glycol monomethyl ether (PGME) as organic solvents A positive resist composition was prepared in the same manner as in Example 1 except that 1250 parts by mass of the mixed solvent (mass ratio 6: 4) was used, and the cation part (PAG +) and the anion part (B) component ( PAG-) The same evaluation as in Example 1 was performed except that the respective concentrations were measured and the elution amount (mol / cm ² ) per square centimeter of the resist layer after exposure was determined. The results are shown in Table 3.

[Comparative Example 5]
In Example 1, a mixture of 3.5 parts by mass of TPS-PFBS and 1.0 part by mass of MTPS-PFMS as component (B), 0.3 parts by mass of triethanolamine as component (D), an organic solvent A positive resist composition was prepared in the same manner as in Example 1 except that 1250 parts by mass of a mixed solvent of PGMEA and ethyl lactate (mass ratio 6: 4) was used as a cation part (PAG +) of component (B). ) And anion part (PAG-) were measured in the same manner as in Example 1 except that the elution amount (mol / cm ² ) per square centimeter of the resist layer after exposure was determined. The results are shown in Table 3.

単位：１０^−１２モル／ｃｍ^２
ND：検出限界以下

Unit: 10 ⁻¹² mol / cm ²
ND: Below detection limit

As is clear from the above results, in the resist composition of Example 4 using TPS-IMIDO corresponding to the onium salt acid generator (B2), both the cation part (PAG +) and the anion part (PAG-) In addition, the amount of elution was small both before and after exposure.
On the other hand, in the resist composition of Comparative Example 5, both the cation part (PAG +) and the anion part (PAG-) were eluted.

[Example 5]
Further, immersion exposure was performed using the positive resist composition of Example 4 (the solid content concentration was changed to 3.5% by mass).
First, an organic antireflection film composition “ARC-29” (trade name, manufactured by Brewer Science) is applied onto a silicon wafer using a spinner, and baked on a hot plate at 215 ° C. for 60 seconds to be dried. Thereby, an organic antireflection film having a thickness of 77 nm was formed. Then, the positive resist composition obtained above is applied onto the antireflection film using a spinner, pre-baked on a hot plate at 125 ° C. for 60 seconds, and dried to form a film on the antireflection film. A resist film having a thickness of 100 nm was formed.
Then, as immersion exposure, immersion two-beam interference exposure was performed by using a two-beam interference exposure machine LEIES 193-1 (manufactured by Nikon) and prism, water, and two beam interferences of 193 nm. Next, PEB treatment was performed at 115 ° C. for 60 seconds, followed by development with an alkali developer at 23 ° C. for 60 seconds. As the alkali developer, an aqueous 2.38 mass% tetramethylammonium hydroxide solution was used.

  When the L & S pattern thus obtained was observed with a scanning electron microscope (SEM), a resist pattern having a 45 nm line and space of 1: 1 was formed. At that time, the resist pattern was highly rectangular.

[Comparative Example 6]
Immersion exposure was performed in the same manner as in Example 5 except that the positive resist composition of Comparative Example 5 (the solid content concentration was changed to 3.5% by mass) and PAB was changed to 115 ° C. .

As a result, when the obtained L & S pattern was observed with a scanning electron microscope (SEM), a resist pattern with a 45 nm line-and-space ratio of 1: 1 was formed. Was insufficient.

  As is clear from the above results, the resist composition of Example 4 in which the amount eluted to the immersion medium was reduced, a fine pattern of 45 nm could be formed and the shape was excellent. However, in the resist composition of Comparative Example 5 in which the amount of eluate in the immersion medium was larger than that in Example 4, although a fine pattern of 45 nm was formed, the rectangularity was insufficient.

Claims (14)

A resist composition for use in a resist pattern forming method comprising a resin component (A) whose alkali solubility is changed by the action of an acid and an acid generator component (B) that generates an acid upon exposure, and a step of immersion exposure. And the said acid generator component (B) contains the onium salt type | system | group acid generator (B1) represented by the following general formula (b-1), The resist composition characterized by the above-mentioned.

[Wherein, R ^{11 to} R ¹³ each independently represents an aryl group or an alkyl group, and at least one of R ^{11 to} R ¹³ represents an aryl group in which at least one hydrogen atom is substituted with an alkyl group. represents, Z ^- represents an anion. ] The resist composition according to claim 1, wherein the onium salt-based acid generator (B1) includes an onium salt-based acid generator (B11) represented by the following general formula (b-2).

[Wherein, R ^{14 to} R ¹⁶ each independently represents an alkyl group, p, q and r each independently represent an integer of 1 to 5, and Z ⁻ represents an anion. ] The resist composition according to claim 1, wherein Z ⁻ is a fluorinated alkyl sulfonate ion. The resist composition as described in any one of Claims 1-3 in which the said onium salt type | system | group acid generator (B11) contains the onium salt type | system | group acid generator (B12) represented by the following general formula (b-3). object.

[Wherein, s represents an integer of 1 to 10. ] A resist composition for use in a resist pattern forming method comprising a resin component (A) whose alkali solubility is changed by the action of an acid and an acid generator component (B) that generates an acid upon exposure, and a step of immersion exposure. A resist composition, wherein the acid generator component (B) contains an onium salt acid generator (B2) having a cyclic group-containing anion. The resist composition according to claim 5, wherein the onium salt-based acid generator (B2) contains a compound (B21) represented by the following general formula (b-4).

[Wherein, X represents an alkylene group having 2 to 6 carbon atoms in which at least one hydrogen atom is substituted with a fluorine atom; R ^{21 to} R ²³ each independently represents an aryl group or an alkyl group; ^At least one of ^{21 to} R ²³ represents an aryl group] The resist composition according to claim 5 or 6, wherein the onium salt-based acid generator (B2) contains a compound (B22) represented by the following general formula (b-5).

[Wherein Y represents a cyclic group; R ^{24 to} R ²⁶ each independently represents an aryl group or an alkyl group, and at least one of R ^{24 to} R ²⁶ represents an aryl group] The resist composition according to claim 7, wherein Y is an aliphatic hydrocarbon group. The resist composition according to claim 7 or 8, wherein Y is an adamantyl group. The resist according to any one of claims 1 to 9, wherein the resin component (A) has a structural unit (a1) derived from an (α-lower alkyl) acrylate ester having an acid dissociable, dissolution inhibiting group. Composition. The resist composition according to claim 10, wherein the resin component (A) further comprises a structural unit (a2) derived from an (α-lower alkyl) acrylate ester having a lactone-containing monocyclic or polycyclic group. The resist composition according to claim 10 or 11, wherein the resin component (A) further comprises a structural unit (a3) derived from an (α-lower alkyl) acrylate ester having a polar group-containing aliphatic hydrocarbon group. Furthermore, the resist composition as described in any one of Claims 1-12 containing a nitrogen-containing organic compound (D). It is a resist pattern formation method using the resist composition as described in any one of Claims 1-13, Comprising: The resist pattern formation method characterized by including the process of immersion exposure.