TWI403845B - Resist composition for liquid immersion lithography and resist pattern forming method - Google Patents

Abstract

Disclosed is a resist composition for immersion exposure, comprising: a resin component (A) whose alkali solubility can be changed by the action of an acid; and an acid-generator component (B) which can generate an acid upon being exposed to light, wherein the acid-generator component (B) comprises an acid-generator (B1) having a cationic moiety represented by the general formula (b1-1). (b1-1) wherein R<SUP>42</SUP> and R<SUP>43</SUP> independently represent an alkyl group, an alkoxy group or a hydroxyl group; and n<SUP>2</SUP> and n<SUP>3</SUP> independently represent an integer ranging from 0 to 2.

Description

Photoresist composition for immersion exposure and method for forming photoresist pattern

The present invention relates to a immersion-type photoresist composition for use in a method for forming a photoresist pattern containing an immersion lithography process, and a method for forming a photoresist pattern.

The present invention claims priority on the basis of Japanese Patent Application No. 2006-148172, filed on Jan. 29, 2006, the entire content of

In recent years, in the manufacture of fine structures of various electronic devices such as semiconductor devices and liquid crystal devices, a photolithography method has been widely used. Therefore, as the device structure is miniaturized, the photoresist pattern in the lithography process is also required to be miniaturized.

At present, in the lithography method, for example, in the field of the most advanced technology using an ArF excimer laser, a fine photoresist pattern having a line width of about 90 nm can be formed, but there will be a demand for further miniaturization in the future.

In order to achieve the formation of the aforementioned fine pattern, the first step must be to develop an exposure device and its corresponding photoresist.

In order to achieve a high resolution, the photoresist has a quantum yield of 1 or more by using a catalyst reaction or a chain reaction of an acid generated by radiation irradiation, and the enhanced chemical resistance of the high sensitivity is greatly increased. Attention, and extensive research and development.

The base resin for enhancing the chemical resistance is a resin which is protected by a polyhydroxystyrene (PHS) having a high transparency to a KrF excimer laser (248 nm) or a hydroxyl group which is protected by an acid dissociable dissolution inhibiting group ( PHS resin), or a resin having an excellent transparency in an ArF excimer laser (near 193 nm) having a structural unit derived from a (meth) acrylate (acrylic resin), the carboxyl group is dissociated by acid dissociation The resin obtained by the inhibition of the base protection is a common user.

Further, the acid dissociable dissolution inhibiting group is known, for example, an acetal group such as ethoxyethyl group, a tertiary alkyl group such as tert-butyl group, a tert-butoxycarbonyl group or a tert-butoxycarbonylmethyl group. For example, a structural unit having an acid dissociable dissolution inhibiting group in the resin component of the conventional ArF positive resist composition is used, and for example, 2-alkyl-2-adamantyl (meth)acrylic acid disclosed in Patent Document 1 below is often used. A structural unit derived from a tertiary ester compound of (meth)acrylic acid such as an ester.

Further, "acrylic acid ester" means one or both of an acrylate having a hydrogen atom bonded to the α-position and a methyl methacrylate bonded to the α-position. "(Meth)acrylate" means an acrylate having a hydrogen atom bonded to the α-position, and one or both of the methyl methacrylate bonded to the α-position. "(Meth)acrylic acid" means one or both of acrylic acid having a hydrogen atom bonded to the α-position and one or both of the methyl methacrylate bonded to the α-position.

Further, in the exposure apparatus, a method of shortening the wavelength of the light source or increasing the number of lens openings (NA), such as a large diameter (high NA), is generally the main method. For example, when the resolution of the photoresist is about 0.5 μm, the main spectrum of the mercury lamp is 364 nm, and when it is about 0.5 to 0.3 μm, the main spectrum of the mercury lamp is 365 nm. When it is about 0.3 to 0.15 μm, 248 nm KrF excimer laser light is used, and when it is about 0.15 μm or less, 193 nm ArF excimer laser light is used.

Further, in order to make it more fine, for example, F ₂ excimer laser (157 nm) or Ar ₂ excimer laser (126 nm), EUV (extreme ultraviolet light, 13.5 nm), EB (electron line), X have been studied. Line and so on.

However, in order to shorten the wavelength of the light source, it is necessary to add a new expensive exposure apparatus. Further, in the case of high NA, since the resolution has a trade-off correlation with the depth of focus (DOF), there is a problem that the depth of focus is lowered even if the resolution is improved.

Among them, there have been reports of immersion lithography methods (for example, Non-Patent Documents 1 to 3).

In the case of exposure, the portion between the lens filled with an inert gas such as air or nitrogen and the photoresist layer on the wafer is filled with a solvent having a refractive index higher than that of air (immersion medium). Exposure (immersion exposure) method.

Under the immersion exposure lithography process, even when a light source of the same exposure wavelength is used, the same high resolution can be achieved as in the case of using a shorter wavelength light source or in the case of using a high NA lens. Reduce the focus of the depth of focus of the focus. Further, the immersion lithography can be performed using an existing exposure apparatus. Therefore, the immersion exposure speculates that a photoresist pattern having high resolution and excellent depth of focus can be obtained at a low cost, and therefore, in the manufacturing technology of a semiconductor element that currently requires a large amount of equipment investment, The lithography characteristics such as resolution can provide excellent results in the semiconductor industry and attract great attention. Currently, infiltration media is mainly for the study of water.

Further, in the method of immersion exposure, it is also possible to prevent the immersion medium from impregnating the photoresist film formed on the wafer, or preventing the sublimation substance generated by the photoresist film from contaminating the lens of the exposure device. A method of forming a top coat film (hereinafter also referred to as "protective film") is provided on the photoresist film.

[Patent Document] Japanese Patent Publication No. Hei 10-161313

[Non-Patent Document 1] Journal of Vacuum Science & Technology B (USA), 1999, Vol. 17, No. 6, pages 3306 to 3309; [Non-Patent Document 2] Journal of Vacuum Science & Technology B (USA), 2001 , Vol. 19, No. 6, pp. 2353 to 2356; [Non-Patent Document 3] Proceedings of SPIE (USA), 2002, Vol. 4691, 459-465

However, in the immersion exposure, there are still many unknowns. Whether the micro-pattern can reach the actual use level still has many difficulties.

For example, in the conventional resist composition for immersion exposure, as described above, when a photoresist pattern having a top coat film on a photoresist film is formed, there is a case where the lithography characteristics are adversely affected. For example, the surface of the photoresist pattern may be roughened, or the line width of the line pattern may be "Line Width Roughness" (hereinafter referred to as "LWR").

The present invention is a solution proposed in view of the foregoing problems, and provides a good lithographic etching property even when a photoresist pattern having a top coat provided on a photoresist film is provided. The purpose of forming a photoresist composition for immersion exposure and a photoresist pattern is for the purpose.

The present inventors have proposed the following means in order to solve the above problems.

That is, the first aspect of the present invention is a wet-type resist composition for immersion exposure, which is a resin component containing (A) a change in alkali solubility due to an action of an acid, and (B) An immersion-type resist composition for producing an acid generator component by exposure, wherein the acid generator component (B) is an acid generator containing a cation portion represented by the following formula (b1-1) ( B1),

[wherein, R ⁴² and R ⁴³ are each independently an alkyl group, an alkoxy group or a hydroxyl group, and n ² and n ³ are each independently an integer of 0 to 2].

Further, a second embodiment of the present invention is a method for forming a photoresist pattern, which comprises forming a photoresist film on a substrate by using the resist composition for immersion exposure using the first embodiment. And the step of immersing the photoresist film to expose the photoresist film to form a photoresist pattern.

In the specification and claims of the present invention, "structural unit" means a monomer unit of a structural resin component (polymer).

"Exposure" is the general concept of radiation exposure.

The "alkyl group" is a linear monovalent, branched, and cyclic monovalent saturated hydrocarbon group, unless otherwise specified.

"Lower alkyl" means an alkyl group having 1 to 5 carbon atoms.

The present invention provides a photoresist composition for immersion exposure and a method for forming a photoresist pattern which can obtain good lithographic etching characteristics even when a photoresist pattern having a top coating film is formed on a photoresist film. .

<Immersion type photoresist composition for exposure>

The photoresist composition for immersion exposure of the present invention contains (A) a resin component which changes the solubility of an alkali by an action of an acid (hereinafter also referred to as a component (A)), and (B) an acid generated by exposure. The immersion exposure photoresist composition of the acid generator component (hereinafter also referred to as (B) component), wherein the component (B) is an acid generator containing a cation portion represented by the formula (b1-1) (B1).

The photoresist composition for immersion exposure of the present invention may be a negative photoresist composition or a positive photoresist composition, and a positive photoresist composition is preferred.

When the photoresist composition for immersion exposure of the present invention is a negative photoresist composition, the component (A) is an alkali-soluble resin, and the negative-type photoresist composition is added with a (C) crosslinking agent.

In the negative-type photoresist composition, when an acid is generated in the component (B) due to exposure when the photoresist pattern is formed, cross-linking occurs between the alkali-soluble resin and the crosslinking agent via the action of the acid. The change is alkali insoluble.

The alkali-soluble resin is a resin having at least one unit selected from the group consisting of α-(hydroxyalkyl)acrylic acid or a lower alkyl ester of α-(hydroxyalkyl)acrylic acid, which is less swollen and can be formed into a good one. The photoresist pattern is preferred. Further, α-(hydroxyalkyl)acrylic acid means an acrylic acid having a hydrogen atom bonded to a carbon atom at the α-position bonded to a carboxyl group, and a hydroxyalkyl group bonded to a carbon atom at the α-position (preferably having a carbon number of 1~) One or both of the α-hydroxyalkylacrylic acid of 5 hydroxyalkyl). The α-(hydroxyalkyl)acrylate refers to an acrylate in which a carbon atom bonded to the α-position of a carbonyl group is bonded with a hydrogen atom, and a hydroxyalkyl group is bonded to the carbon atom at the α-position (preferably, the number of carbon atoms is 1~) One or both of the α-hydroxyalkyl acrylates of 5 hydroxyalkyl groups.

The crosslinking agent (C), for example, is generally an amine-based crosslinking agent such as glycoluril having a methylol group or an alkoxymethyl group, and is preferably formed into a good photoresist pattern having less swelling. . The amount of the crosslinking agent (C) to be added is preferably in the range of 1 to 50 parts by mass based on 100 parts by mass of the alkali-soluble resin.

Further, when the resist composition for immersion exposure of the present invention is a positive photoresist composition, the component (A), that is, an alkali-insoluble component having an acid-dissociable dissolution inhibiting group, when forming a photoresist pattern, When the acid of the component (B) is generated by exposure, the acid dissociable dissolution inhibiting group is dissociated via the acid, and the component (A) is made alkali-soluble. Therefore, in the formation of the photoresist pattern, when the photoresist film coated on the substrate is selectively exposed by the positive photoresist composition, the exposed portion can be converted into an alkali-soluble, unexposed portion. The alkali insoluble state is maintained, and alkali development can be performed.

In the resist composition for immersion exposure of the present invention, the component (A) is preferably a resin component (A1) (hereinafter also referred to as (A1) component) which increases alkali solubility by the action of an acid. That is, the positive-type photoresist composition for immersion exposure of the present invention is preferably a positive-type photoresist composition.

Next, the (A1) component which is preferably used for the positive-type resist composition for immersion exposure will be exemplified.

<(A1) ingredient>

In the positive resist composition for the immersion liquid exposure, the (A1) component which is preferably used is preferably a structural unit (a1) derived from an acrylate having an acid dissociable dissolution inhibiting group.

Further, the component (A1) is preferably a structural unit (a2) derived from an acrylate having a cyclic group containing a lactone.

Further, the component (A1) is preferably a structural unit (a3) derived from an acrylate having an aliphatic hydrocarbon group having a polar group.

In the present specification and the scope of the patent application, "the structural unit derived from the acrylate" means the structural unit constituted by the cracking of the ethylenic double bond of the acrylate.

The "acrylate" refers to a concept in which a carbon atom in the alpha position is a compound in which a carbon atom bonded to a hydrogen atom is bonded to a carbon atom at the alpha position (atom or a group other than a hydrogen atom).

The substituent is, for example, a halogen atom, a lower alkyl group, a halogenated lower alkyl group or the like. A halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, an iodine atom or the like is preferable, and a fluorine atom is particularly preferable.

Further, the α-position (carbon atom at the α-position) of the structural unit derived from the acrylate means a carbon atom bonded to the carbonyl group unless otherwise specified.

In the acrylate, a lower alkyl group of the substituent at the α-position, specifically, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isoprene group A linear or branched chain lower alkyl group such as a benzyl group or a neopentyl group. The halogenated lower alkyl group substituted with an α-position, for example, a group obtained by substituting at least one hydrogen atom with a halogen atom in a specific example of the above lower alkyl group.

In the present invention, the α-position of the acrylate is bonded with a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group, and a hydrogen atom, a fluorine atom, a lower alkyl group or a fluorinated lower alkyl group. More preferably, it is preferable to use a hydrogen atom or a methyl group from the viewpoint of easy industrial availability.

. Structural unit (a1) structural unit (a1), a structural unit derived from an acrylate having an acid dissociable dissolution inhibiting group.

The acid dissociable dissolution inhibiting group in the structural unit (a1) is such that, as long as the (A1) component has an alkali-insoluble alkali dissolution inhibiting property before dissociation, the entire component (A1) is changed to alkali solubility after dissociation. The base may be used, and it is possible to use an acid dissociable dissolution inhibiting group which has been proposed as a base resin for enhancing a chemical type resist composition.

In general, for example, a carboxyl group or a chain-like tertiary alkyl ester group or a acetal acid dissociable dissolution inhibiting group such as an alkoxyalkyl group can be formed with a carboxyl group in (meth)acrylic acid.

Here, the "trialkyl ester", for example, a hydrogen atom of a carboxyl group is substituted with a chain or a cyclic alkyl group to form an ester, and an oxygen atom at the terminal of the carbonyloxy group (-C(O)-O-) is bonded. A structure obtained by the tertiary carbon atom of the above-mentioned chain or cyclic alkyl group. In the above tertiary alkyl ester, the bond between the oxygen atom and the tertiary carbon atom can be interrupted by the action of an acid.

Further, the aforementioned chain or cyclic alkyl group may have a substituent.

Hereinafter, the acid dissociable group composed of a carboxyl group and a tertiary alkyl ester is conveniently referred to as a "triester alkyl ester type acid dissociable dissolution inhibiting group".

The tertiary alkyl ester type acid dissociable dissolution inhibiting group is, for example, an aliphatic branched chain acid dissociable dissolution inhibiting group, an acid dissociable dissolution inhibiting group containing an aliphatic cyclic group, and the like.

The term "aliphatic" as used in the scope of the present application and the specification refers to the relative concept of aromatics, that is, the meaning of a group or a compound having no aromaticity.

The "aliphatic branched chain" means a branched chain structure having no aromaticity.

The structure of the "aliphatic branched chain acid dissociable dissolution inhibiting group" is not limited to a group (hydrocarbon group) formed of carbon and hydrogen, but a hydrocarbon group is preferred.

Further, the "hydrocarbon group" may be either saturated or unsaturated, and it is generally preferred to saturate.

The aliphatic branched chain acid dissociable dissolution inhibiting group is preferably a C 4 to 8 tertiary alkyl group, specifically, for example, tert-butyl, tert-pentyl, tert-heptyl or the like.

The "aliphatic cyclic group" means a monocyclic or polycyclic group having no aromaticity.

The "aliphatic cyclic group" in the structural unit (a1) is preferably a carbon number of 4 to 20, and may have a substituent or may not have a substituent. The substituent is, for example, a lower alkyl group having 1 to 5 carbon atoms, a fluorine atom, a fluorinated lower alkyl group having 1 to 5 carbon atoms substituted by a fluorine atom, an oxygen atom (=O) or the like.

The basic ring structure in which the substituent is removed in the "aliphatic cyclic group" is not limited to a group (hydrocarbon group) composed of carbon and hydrogen, but a hydrocarbon group is preferred. Further, the "hydrocarbon group" may be either saturated or unsaturated, and generally it is preferably saturated. The "aliphatic cyclic group" is preferably a polycyclic group.

Specific examples of the aliphatic cyclic group, for example, may be substituted by a lower alkyl group, a fluorine atom or a fluorinated alkyl group having 1 to 5 carbon atoms, or a monocyclic alkane or a dicycloalkane which may be unsubstituted. A group obtained by removing at least one hydrogen atom from a polycyclic alkane such as a tricycloalkane or a tetracycloalkane. Specifically, for example, at least 1 is removed from a monocyclic alkane such as cyclopentane or cyclohexane or a polycyclic alkane such as adamantane, raw spinane, isopentane, tricyclodecane or tetracyclododecane. The basis of a hydrogen atom.

Further, the acid dissociable dissolution inhibiting group containing an aliphatic cyclic group, for example, a group having a tertiary carbon atom in a ring skeleton of a cyclic alkyl group, etc., specifically, for example, 2-methyl-2-adamantane Base, or 2-ethyl-2-adamantyl and the like. Or, for example, in the structural unit represented by the following formula (a1"), an aliphatic ring group such as an adamantyl group is bonded to a group of an oxygen atom of a carbonyloxy group (-C-(O)-O-). And a group having a branched chain alkyl group having a tertiary carbon atom bonded thereto.

Wherein R is an atom or a group bonded to the carbon atom at the alpha position of the above acrylate, such as a hydrogen atom, a halogen atom, a lower alkyl group or a halogenated lower alkyl group; and R ¹⁵ and R ¹⁶ are an alkyl group (which may be straight) Both chains and branched chains may be used, preferably having a carbon number of 1 to 5)].

The "acetal type acid dissociable dissolution inhibiting group" is generally an oxygen atom bonded to a hydrogen atom at the terminal of an alkali-soluble group such as a carboxyl group or a hydroxyl group. Therefore, when an acid is generated by exposure, the bond between the acetal type acid dissociable dissolution inhibiting group and the oxygen atom to which the acetal type acid dissociable dissolution inhibiting group is bonded is cut off based on the action of the acid.

The acetal type acid dissociable dissolution inhibiting group is, for example, a group represented by the following formula (p1).

Wherein R ^{1 '} and R ^{2 '} are each independently a hydrogen atom or a lower alkyl group, n is an integer of 0 to 3, and Y is a lower alkyl group or an aliphatic cyclic group]

In the above formula, n is preferably an integer of 0 to 2, more preferably 0 or 1, and most preferably 0.

The lower alkyl group of R ^{1 '} and R ^{2 '} is, for example, the same as the lower alkyl group of the above R, and preferably a methyl group or an ethyl group, and a methyl group is most preferable.

In the present invention, it is preferred that at least one of R ^{1 '} and R ^2' is a hydrogen atom. In other words, the acid dissociable dissolution inhibiting group (p1) is preferably a group represented by the following formula (p1-1).

The lower alkyl group of Y is, for example, the same as the lower alkyl group of the above R.

The aliphatic ring group of Y may be appropriately selected from among the monocyclic or polycyclic aliphatic ring groups which have been proposed many times in the conventional ArF photoresist, etc., and have a carbon number of 4 to 20 It is better.

[In the formula, R ^{1 '} , n, and Y are the same as those described above. 〕

The lower alkyl group of Y is, for example, the same as the lower alkyl group of the above R.

The aliphatic ring group of Y may be appropriately selected from among the monocyclic or polycyclic aliphatic ring groups which have been proposed many times in the conventional ArF photoresist, for example, and the above-mentioned "aliphatic ring type". The base is the same content.

Further, the acetal type acid dissociable dissolution inhibiting group is, for example, a group represented by the following formula (p2).

[wherein, R ¹⁷ and R ¹⁸ are each independently a linear or branched alkyl group or a hydrogen atom, and R ¹⁹ is a linear, branched or cyclic alkyl group, or each of R ¹⁷ and R ¹⁹ independently a linear or branched alkylene of chain, R ¹⁷ and R-terminal end of the bond of the junction ¹⁹ may form a ring]

In R ¹⁷ and R ¹⁸ , the alkyl group preferably has 1 to 15 carbon atoms, and may be linear or branched, preferably ethyl or methyl, and most preferably methyl.

In particular, any of R ¹⁷ and R ¹⁸ is a hydrogen atom, and the other is preferably a methyl group.

When R ¹⁹ is a linear, branched or cyclic alkyl group, the carbon number is preferably from 1 to 15, and it may be any of a linear chain, a branched chain or a ring.

When R ¹⁹ is a linear or branched chain, the carbon number is preferably from 1 to 5, more preferably ethyl or methyl, and most preferably ethyl.

When R ¹⁹ is a ring, it is preferably 4 to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and most preferably 5 to 10 carbon atoms. Specifically, it may be substituted by a fluorine atom or a fluorinated alkyl group having 1 to 5 carbon atoms, or a monocyclic alkane, a bicycloalkane, a tricycloalkane or a tetracycloalkane which are not substituted. A group of one or more hydrogen atoms is removed from the cycloalkane. Specifically, for example, a monocyclic alkane such as cyclopentane or cyclohexane or one or more polycyclic alkane such as adamantane, raw spinane, isopentane, tricyclodecane or tetracyclododecane is removed. The base of a hydrogen atom, etc. Among them, the base obtained by removing one or more hydrogen atoms from adamantane is preferred.

Further, in the above formula, R ¹⁷ and R ¹⁸ are each independently a linear or branched alkyl group (preferably a C 1 to 5 alkyl group), and the end of R ¹⁹ may be combined with R ¹⁷ The end of the bond can also be.

At this time, R ¹⁷ and R ¹⁹ , and an oxygen atom bonded to R ¹⁹ form a cyclic group with the oxygen atom bonded to the carbon atom bonded to R ¹⁷ . The ring base is preferably a 4 to 7 member ring, and a 4 to 6 member ring is preferred. Specific examples of the cyclic group include, for example, a tetrahydropyranyl group, a tetrahydrofuranyl group and the like.

The structural unit (a1) is one or more selected from the group consisting of the structural unit represented by the following formula (a1-0-1) and the structural unit represented by the following formula (a1-0-2). good.

(wherein R has the same content as described above; and X ¹ is an acid dissociable dissolution inhibiting group)

(wherein R has the same content as described above; X ² is an acid dissociable dissolution inhibiting group; Y ² is an alkylene group or an aliphatic cyclic group)

In the formula (a1-0-1), the halogen atom, the lower alkyl group or the halogenated lower alkyl group of R is the same as the above-mentioned halogen atom which may be bonded to the α-position of the acrylate, lower alkyl group or halogenated lower alkyl group. The content.

X ¹ is not particularly limited as long as it is an acid dissociable dissolution inhibiting group, and may be, for example, a tertiary alkyl ester type acid dissociable dissolution inhibiting group or an acetal type acid dissociating dissolution inhibiting group, and a trisalkane. The ester-type acid dissociable dissolution inhibiting group is preferred.

In the formula (a1-0-2), R has the same content as described above.

X ² is the same as X ¹ in the formula (a1-0-1).

Y ^{2 is} preferably an alkylene group having 1 to 4 carbon atoms or a divalent aliphatic cyclic group. In the case of the aliphatic cyclic group, the same as the description of the above-mentioned "aliphatic cyclic group" can be used, for example, in addition to the group in which two or more hydrogen atoms are removed.

In the structural unit (a1), more specifically, for example, the structural unit represented by the following general formulae (a1-1) to (a1-4).

[In the above formula, X' is a tertiary alkyl ester type acid dissociable dissolution inhibiting group; Y has the same content as described above; n is an integer of 0 to 3; m is 0 or 1; and R has the above The same content; R ^{1 '} and R ^{2 '} are each independently a hydrogen atom or a lower alkyl group having 1 to 5 carbon atoms]

It is preferable that at least one of R ^{1 '} and R ^2' is a hydrogen atom, and more preferably a hydrogen atom at the same time. n is preferably 0 or 1.

The content of X' is the same as that of the cyclic tertiary alkyl ester type acid dissociable dissolution inhibiting group exemplified in the above X ¹ .

The aliphatic cyclic group of Y is, for example, the same as that exemplified in the description of the above "aliphatic cyclic group".

The following are specific examples of the structural unit represented by the above general formulae (a1-1) to (a1-4).

The structural unit (a1) may be used alone or in combination of two or more.

Among them, the structural unit represented by the formula (a1-1) is preferred. Specifically, at least one selected from the structural units represented by the formulae (a1-1-1) to (a1-1-6) or the formulas (a1-1-35) to (a1-1-41) is used. For the best.

Further, the structural unit (a1) is specifically a unit represented by the following general formula (a1-1-01) including the structural unit of the formula (a1-1-1) to the formula (a1-1-4), or The following general formula (a1-1-02) of the structural unit of the formula (a1-1-35) to (a1-1-41) is preferred.

(wherein R has the same content as described above, and R ¹¹ is a lower alkyl group)

(wherein R has the same content as described above, R ¹² is a lower alkyl group, and h is an integer of 1 to 3)

In the formula (a1-1-01), R has the same content as described above. The lower alkyl group of R ¹¹ is the same as the lower alkyl group represented by R, and a methyl group or an ethyl group is preferred.

In the formula (a1-1-02), R has the same content as described above. The lower alkyl group of R ¹² is the same as the lower alkyl group represented by R, and is preferably a methyl group or an ethyl group, and preferably an ethyl group. h is preferably 1 or 2, and 2 is the best.

In the component (A1), the ratio of the structural unit (a1) is preferably from 10 to 80 mol%, more preferably from 20 to 70 mol%, based on the entire structural unit constituting the component (A1). 25 to 50 mol% is the best. When it is more than the lower limit value, it can be easily formed into a pattern when it is a positive-type photoresist composition for immersion exposure, and when it is less than an upper limit, it can balance with another structural unit.

. Structural unit (a2) In the present invention, the component (A1) is preferably a structural unit (a2) derived from an acrylate having a cyclic group containing a lactone, in addition to the above structural unit (a1).

Wherein the cyclic group containing a lactone is a cyclic group containing one ring of the -O-C(O)- structure. The lactone ring is counted as a ring unit, and the monocyclic group is only a lactone ring. If it has other ring structures, it is called a polycyclic group regardless of its structure.

The structural unit (a2) contains a lactone ring group, and in the case where the (A1) component is used for forming a photoresist film, the adhesion of the photoresist film to the substrate can be effectively improved, and the hydrophilicity can be improved, so It is effective from the viewpoint of improving the affinity with the developer.

Among them, the structural unit (a2) can be used without any limitation.

Specifically, a monocyclic group containing a lactone, for example, a group obtained by removing one hydrogen atom from γ-butyrolactone or the like. Further, the polycyclic group having a lactone is, for example, a group obtained by removing one hydrogen atom from a bicycloalkane having a lactone ring, a tricycloalkane or a tetracycloalkane.

In the example of the structural unit (a2), more specifically, for example, a structural unit represented by the following general formulae (a2-1) to (a2-5).

Wherein R has the same content as described above, and R' is each independently a hydrogen atom, a lower alkyl group, or an alkoxy group having 1 to 5 carbon atoms, and m is an integer of 0 or 1]

In the formulae (a2-1) to (a2-5), R has the same content as R in the above structural unit (a1).

The lower alkyl group of R' has the same content as the lower alkyl group of R in the above structural unit (a1).

Among the formulae (a2-1) to (a2-5), R' is preferably a hydrogen atom from the viewpoint of industrial availability.

The following are examples of specific structural units of the above general formulae (a2-1) to (a2-5).

Wherein, at least one selected from the structural units represented by the formulas (a2-1) to (a2-5) is preferably used, and at least one selected from the formulas (a2-1) to (a2-3) One is better. Specifically, at least one of the formulas (a2-1-1), (a2-1-2), (a2-2-1), (a2-2-2), (a2-3-1) is used. The selected ones of (a2-3-2), (a2-3-9) and (a2-3-10) are the best.

In the component (A1), the structural unit (a2) may be used alone or in combination of two or more.

The ratio of the structural unit (a2) in the component (A1) is preferably from 5 to 60 mol%, more preferably from 10 to 50 mol%, based on the total of the structural units constituting the component (A1). 20 to 50 mol% is the best. When it is more than the lower limit, the effect can be sufficiently obtained when the structural unit (a2) is contained, and when it is equal to or less than the upper limit, a balance with other structural units can be obtained.

. Structural unit (a3) In the present invention, the component (A1) further contains (a3) an aliphatic hydrocarbon group having a polar group in addition to the structural unit (a1) or the structural units (a1) and (a2). The structural unit derived from the acrylate is preferred. When the structural unit (a3) is contained, the hydrophilicity of the component (A1) can be improved, and the affinity with the developer can be improved, and the alkali solubility of the exposed portion can be improved, and the resolution can be expected to be improved.

The polar group, for example, a hydroxyl group, a cyano group, a carboxyl group, a hydroxyalkyl group in which at least one hydrogen atom of the alkyl group having 1 to 5 carbon atoms is substituted by a fluorine atom, and the like, preferably a hydroxyl group.

An aliphatic hydrocarbon group, for example, a linear or branched hydrocarbon group having 1 to 10 carbon atoms (preferably an alkylene group), or a polycyclic hydrocarbon group having a carbon number of 4 to 20 (polycyclic group) . The polycyclic group may be, for example, a resin which can be used for a resist composition for an ArF excimer laser, and is appropriately selected from many proposals.

Further, it is derived from an aliphatic polycyclic acrylate having a hydroxyl group, a cyano group, a carboxyl group, or a hydroxyalkyl group having at least one hydrogen atom substituted by a fluorine atom in an alkyl group having 1 to 5 carbon atoms. The structural unit is better. The polycyclic group is, for example, a group obtained by removing one or more hydrogen atoms from a bicycloalkane, a tricycloalkane or a tetracycloalkane. Specifically, for example, a group obtained by removing one or more hydrogen atoms from a polycyclic alkane such as adamantane, raw spinane, isopentane, tricyclodecane or tetracyclododecane is used. In the above polycyclic group, it is more suitable for industrial use to remove two or more hydrogen atoms from adamantane, to remove two or more hydrogen atoms from the original spinel, and to remove two or more hydrogen atoms from tetracyclododecane. use.

In the structural unit (a3), when the hydrocarbon group in the aliphatic hydrocarbon group having a polar group is a linear or branched hydrocarbon group having 1 to 10 carbon atoms, the structural unit derived from hydroxyethyl acrylate is preferred. When the hydrocarbon group is a polycyclic group, for example, a structural unit represented by the following formula (a3-1), a structural unit represented by (a3-2), a structural unit represented by (a3-3), or the like is preferable.

(wherein R has the same content as described above, j is an integer of 1 to 3, k is an integer of 1 to 3, t' is an integer of 1 to 3, 1 is an integer of 1 to 5, and s is 1 to 3 integer)

In the formula (a3-1), it is preferable that j is 1 or 2, and 1 is more preferable. In the case where j is 2, it is more preferable that the hydroxyl group is bonded to the 3 and 5 positions of the adamantyl group. In the case where j is 1, it is particularly preferable that the hydroxyl group is bonded to the 3 position of the adamantyl group.

Among them, j is preferably one, and especially the hydroxy group bonded to the adamantyl group is the best.

In the formula (a3-2), it is preferred that k is one. Further, it is preferred that the cyano group is bonded to the 5- or 6-position of the original spinnyl group.

In the formula (a3-3), it is preferable that t' is one, and one is preferably one, and s is one. A compound in which a terminal of a carboxyl group of the above acrylic acid is bonded to a 2-pyrrolidyl group or a 3-pyrosylalkyl group is preferred. The fluorinated alkyl alcohol is preferably bonded to the 5 or 6 position of the original spinnyl group.

In the component (A1), the structural unit (a3) may be used singly or in combination of two or more.

The ratio of the structural unit (a3) in the component (A1) is preferably 5 to 50 mol%, more preferably 5 to 40 mol%, and more preferably 5 to 50% of the total structural unit constituting the component (A1). 25% Mo is the best. When it is more than the lower limit value, the effect of containing the structural unit (a3) can be sufficiently obtained, and when it is less than the upper limit value, the balance with other structural units can be obtained.

. The structural unit (a4) (A1) component may further contain other structural units (a4) other than the above structural units (a1) to (a3) insofar as the effects of the present invention are not impaired.

The structural unit (a4) is not particularly limited as long as it is a structural unit that is not classified into the structural units (a1) to (a3). It is possible to use a conventionally known structural unit used for a photoresist composition such as ArF excimer laser or KrF excimer laser (preferably for ArF excimer laser).

The structural unit (a4), for example, a structural unit derived from an acrylate having a non-acid dissociable aliphatic polycyclic group is preferable. The polycyclic group is, for example, the same as exemplified in the above structural unit (a1), and can be used for ArF excimer laser or KrF excimer laser (preferably for ArF excimer laser). Most of the structural units previously known for use in the resin composition of the photoresist composition.

In particular, when at least one selected from the group consisting of a tricyclodecylalkyl group, an adamantyl group, a tetracyclododecyl group, an iso-spinyl group, and a raw spintenyl group is industrially easy to obtain, it is preferred. The polycyclic group may be substituted by a linear or branched alkyl group having 1 to 5 carbon atoms.

The structural unit (a4) is specifically, for example, a structural unit represented by the following general formulae (a4-1) to (a4-5).

(where R has the same content as described above)

When the structural unit (a4) is contained in the component (A), the ratio of the structural unit (a4) is preferably from 1 to 30 mol%, based on the total of the structural units constituting the component (A1). It is more preferably contained in an amount of 10 to 20 mol%.

In the present invention, the component (A1) is a resin component (polymer) which is increased in solubility based on the action of an acid, and is suitable as a unit of the resin component (polymer), for example, having a structural unit (a1) and a structural unit (a2). And a copolymer of the structural unit (a3), the copolymer, for example, a copolymer obtained from structural units (a1), (a2), and (a3), structural units (a1), (a2), (a3) And the copolymer obtained by (a4).

In the present invention, the component (A) is particularly preferably a copolymer (A1-1) containing a combination of structural units represented by the following formula (A1-1).

[wherein R has the same content as described above. R ²⁰ is a lower alkyl group. ]

In the formula (A1-1), R has the same content as described above, and further preferably a hydrogen atom or a methyl group.

R ²⁰ is a lower alkyl group, of which methyl or ethyl is preferred, and methyl is preferred.

In the component (A), the copolymer (A1-1) may be used singly or in combination of two or more.

The content of the copolymer (A1-1) in the component (A) is preferably 70% by mass or more, more preferably 80% by mass or more, and most preferably 100% by mass. When it is more than the lower limit of this range, when it is a positive-type photoresist composition for immersion type exposure, the lithography etch characteristic can be raised again.

The component (A1) can be obtained, for example, by polymerization of a monomer derived from each structural unit, for example, a radical polymerization initiator such as azobisisobutyronitrile (AIBN) by a known radical polymerization.

And, (A1) component, on the occasion of the above-described polymerization, for example, and, at the end introduced and -C (CF ₃ by _{HS-CH 2 -CH 2 -CH 2} -C (CF 3) 2 -OH chain transfer agent, etc. ) ₂ -OH group. Thus, a copolymer in which at least one hydrogen atom having an alkyl group substituted with a fluorine atom is introduced can be obtained, whereby the defect can be effectively reduced or the LER (Line Edge Roughness) can be effectively reduced.

The mass average molecular weight (Mw) of the component (A1) (the polystyrene equivalent amount of the gel permeation chromatography method) is not particularly limited, and is generally preferably 2,000 to 50,000, more preferably 3,000 to 30,000, and 5,000. Up to 20,000 is the best. When it is less than the upper limit of the range, sufficient solubility is obtained for the photoresist as a photoresist, and when it is larger than the lower limit of the range, a good dry etching resistance or a resist pattern cross-sectional shape can be obtained.

Further, the degree of dispersion (Mw/Mn) is preferably in the range of 1.0 to 5.0, more preferably 1.0 to 3.0, and most preferably 1.2 to 2.5. Further, Mn is a number average molecular weight.

In addition, as the component (A1), an alkali-soluble resin component other than the copolymer (A1-1) may be, for example, another polymer compound used in a conventional positive-type photoresist composition.

In the positive-type photoresist composition for immersion exposure of the present invention, the content of the component (A1) may be appropriately adjusted in accordance with the thickness of the photoresist film to be formed.

<(B) ingredients>

In the resist composition for immersion exposure of the present invention, the component (B) is an acid generator (B1) containing a cationic portion represented by the above formula (b1-1) (hereinafter, also referred to as a (B1) component. ) The ingredients. When the component (B1) is contained, when the photoresist composition for immersion exposure is formed, even if a photoresist pattern having a top coat on the photoresist film is formed, it is good. Photolithography etching characteristics.

Further, the (B1) component can be added in a large amount to the immersion exposure photoresist composition.

The reason for this is presumed to be an effect obtained by extremely high transparency (inhibition of light absorption) with respect to the exposure wavelength band (particularly, the wavelength region of the ArF excimer laser).

In the above formula (b1-1), R ⁴² and R ⁴³ are each independently an alkyl group, an alkoxy group or a hydroxyl group.

In R ⁴² and R ⁴³ , the alkyl group is preferably a lower alkyl group having 1 to 5 carbon atoms, more preferably a linear or branched alkyl group, and a methyl group, an ethyl group, a propyl group, and a n group. - Butyl and tert-butyl are preferred.

The alkoxy group is preferably an alkoxy group having 1 to 5 carbon atoms, more preferably a linear or branched alkoxy group, and most preferably a methoxy group or an ethoxy group.

n ² and n ³ are each independently an integer of 0 to 2, preferably each independently 0 or 1, more preferably 0.

Further, when n ² or n ³ is 2, two R ⁴² or two R ⁴³ may be the same or different.

The anion portion in the component (B1) is not particularly limited, and a component known as an anion portion of a sulfonium acid generator can be generally used.

For example, an anion moiety represented by the general formula "R ¹⁴ SO ₃ ^- (R ¹⁴ is a linear, branched or cyclic alkyl group or a fluorinated alkyl group)", the following formula (b-3) can be used. The anion moiety shown, the anion moiety represented by the following formula (b-4), and the like.

[wherein, X" is an alkylene group having 2 to 6 carbon atoms in which at least one hydrogen atom is replaced by a fluorine atom; Y", Z" are each independently a carbon number of 1 to 10 in which at least one hydrogen atom is replaced by a fluorine atom. Alkyl]

The above formula "R ¹⁴ SO ₃ ^- "R ¹⁴ is a linear, branched or cyclic alkyl group or a fluorinated alkyl group.

The linear or branched chain alkyl group of the above R ¹⁴ is preferably a carbon number of 1 to 10, more preferably a carbon number of 1 to 8, and most preferably a carbon number of 1 to 4.

The cyclic alkyl group of R ¹⁴ is preferably a carbon number of 4 to 15, preferably 4 to 10 carbon atoms, and particularly preferably 6 to 10 carbon atoms.

When the fluorinated alkyl group of R ¹⁴ is linear or branched, the number of carbon atoms is preferably from 1 to 10, more preferably from 1 to 8 carbon atoms, and most preferably from 1 to 4 carbon atoms. When the fluorinated alkyl group is cyclic, it is preferably 4 to 15 carbon atoms, most preferably 4 to 10 carbon atoms, and particularly preferably 6 to 10 carbon atoms. Further, the fluorination ratio of the fluorinated alkyl group (the ratio of the number of substituted fluorine atoms to the number of all hydrogen atoms in the alkyl group, the same applies hereinafter) is preferably from 10 to 100%, more preferably From 50 to 100%, especially in the case where all hydrogen atoms are replaced by fluorine atoms, it is more preferable to increase the strength of the acid.

R ^{14 is} preferably a linear or cyclic alkyl group or a fluorinated alkyl group.

In the formula (b-3), X" is a linear or branched alkyl group in which at least one hydrogen atom is substituted by a fluorine atom, and the carbon number of the alkyl group is preferably from 2 to 6, more preferably The carbon number is 3 to 5, and the carbon number is 3.

In the formula (b-4), Y" and Z" are each independently a linear or branched alkyl group in which at least one hydrogen atom is substituted by a fluorine atom, and the alkyl group preferably has 1 to 10 carbon atoms. More preferably, the carbon number is from 1 to 7, and the most preferred carbon number is from 1 to 3.

When the carbon number of the alkyl group of X" or the carbon number of the alkyl group of Y" or Z" is in the above carbon number range, it is preferably as small as possible because of the excellent solubility to the photoresist solvent.

Further, in the alkyl group of X" or the alkyl group of Y" or Z", the more the number of hydrogen atoms substituted by fluorine atoms, the stronger the strength of the acid, and the higher the energy of light of 200 nm or less. Or the transparency of the electron beam is preferred. The fluorination ratio of the alkyl or alkyl group is preferably from 70 to 100%, more preferably from 90 to 100%, and most preferably all of the hydrogen atoms are replaced by fluorine atoms. Perfluoroalkylene or perfluoroalkyl.

The anion moiety in the component (B-1) is preferably an anion moiety represented by the formula "R ¹⁴ SO ₃ ^- ", and more preferably R ¹⁴ is a fluorinated alkyl group.

Preferred examples of the component (B1) are as shown below.

Among these, at least one selected from the acid generators represented by the above chemical formulas (b1-01) to (b1-03) is particularly preferable.

(B1) The components may be used alone or in combination of two or more.

In the resist composition for immersion exposure of the present invention, the content of the component (B1) in the entire component (B) is preferably 40% by mass or more, more preferably 70% by mass or more, and most preferably 100% by mass. Above the lower limit of the range, in particular, when the top coat film is formed on the photoresist film to form a photoresist pattern, the lithography characteristics are improved.

Further, in the resist composition for immersion exposure of the present invention, the content of the component (B1) is preferably from 1 to 30 parts by mass, more preferably from 5 to 20 parts by mass, per 100 parts by mass of the component (A). 7 to 18 parts by mass is the best. When the photoresist pattern is formed by providing a top coat film on the photoresist film or more in the range of the lower limit of the range, the lithography characteristics are improved. On the other hand, storage stability is improved by being equal to or less than the upper limit.

In the component (B), an acid generator (B2) other than the above component (B1) (hereinafter also referred to as a component (B2)) may be used in combination with the component (B1).

The component (B2) is not particularly limited as long as it is not in the above (B1) component, and it can be used as a component of an acid generator which has been proposed as an enhanced chemical resist.

The acid generator is, for example, a sulfonium acid generator such as an iodonium salt or a sulfonium salt, an oxime sulfonate acid generator, a dialkyl or bisarylsulfonyldiazomethane, or a polysulfonate. Hydrazine-based diazomethane-based acid generator, nitrobenzyl sulfonate-based acid generator, iminosulfonate-based acid generator, diterpenoid acid generator, etc. Compound.

The hydrazine salt-based acid generator is, for example, an acid generator represented by the following formula (b-0).

[wherein R ⁵¹ is a linear, branched or cyclic alkyl group, or a linear, branched or cyclic fluorinated alkyl group; and R ⁵² is a hydrogen atom, a hydroxyl group, a halogen atom, halogenated alkyl of straight or branched chain, of straight or branched chain (hereinafter, also referred to as a halogenated alkyl group), or a linear or branched alkoxy group of chain; R ⁵³ to be An aryl group having a substituent; u" is an integer of 1 to 3]

In the formula (b-0), R ⁵¹ is a linear, branched or cyclic alkyl group, or a linear, branched or cyclic fluorinated alkyl group.

The linear or branched alkyl group is preferably a carbon number of 1 to 10, more preferably a carbon number of 1 to 8, and most preferably a carbon number of 1 to 4.

The above-mentioned cyclic alkyl group is preferably a carbon number of 4 to 12, most preferably a carbon number of 5 to 10, and particularly preferably a carbon number of 6 to 10.

The linear or branched fluorinated alkyl group is preferably a carbon number of 1 to 10, more preferably a carbon number of 1 to 8, and most preferably a carbon number of 1 to 4.

The above cyclic fluorinated alkyl group is preferably a carbon number of 4 to 12, most preferably a carbon number of 5 to 10, and particularly preferably a carbon number of 6 to 10.

Further, the fluorination ratio of the fluorinated alkyl group (the ratio of the number of fluorine atoms to be substituted with respect to the number of all hydrogen atoms in the alkyl group) is preferably from 10 to 100%, more preferably from 50 to 100. %, especially in the case where all hydrogen atoms are replaced by fluorine atoms, it is more preferable to increase the strength of the acid.

R ^{51 is} preferably a linear alkyl group or a fluorinated alkyl group.

R ⁵² is a hydrogen atom, a hydroxyl group, a halogen atom, a linear or branched alkyl group, a linear or branched halogenated alkyl group, or a linear or branched alkoxy group.

In R ⁵² , a halogen atom, for example, a fluorine atom, a bromine atom, a chlorine atom, an iodine atom or the like, is preferably a fluorine atom.

In R ⁵² , the alkyl group is linear or branched, and its carbon number is preferably from 1 to 5, more preferably from 1 to 4, most preferably from 1 to 3.

In R ⁵² , the halogenated alkyl group is a group in which at least one hydrogen atom or all of the alkyl group is substituted by a halogen atom. The alkyl group therein is, for example, the same as the "alkyl group" in the above R ⁵² . The halogen atom to be substituted is, for example, the same as that described above for the "halogen atom". The halogenated alkyl group is preferably one obtained by substituting 50 to 100% of the total number of hydrogen atoms with a halogen atom, and more preferably all of them are substituted.

In R ⁵² , the alkoxy group is linear or branched, and its carbon number is preferably from 1 to 5, particularly from 1 to 4, most preferably from 1 to 3.

R ⁵² , wherein a hydrogen atom is preferred.

R ⁵³ is an aryl group which may have a substituent, and the structure of the basic ring (parent ring) from which the substituent is removed may be, for example, a naphthyl group, a phenyl group, a fluorenyl group or the like, and the effect of the present invention or an ArF excimer laser or the like. From the viewpoint of absorption of exposure light, etc., a phenyl group is preferred.

The substituent is, for example, a hydroxyl group or a lower alkyl group (linear or branched, preferably having a carbon number of 5 or less and more preferably a methyl group).

The aryl group of R ⁵³ is more preferably one having no substituent.

u" is an integer from 1 to 3, and more preferably 2 or 3, especially 3 is optimal.

A preferred example of the acid generator represented by the formula (b-0) is as shown below.

The acid generators of the formula (b-0) may be used singly or in combination of two or more.

Further, the onium acid generator other than the acid generator represented by the above formula (b-0) is, for example, a compound represented by the following formula (b-1) or (b-2).

Wherein R ^1" to R ^3" , R ^5" and R ^6" are each independently an aryl group or an alkyl group; and R ^4" is a linear, branched or cyclic alkyl group or a fluorinated alkyl group. At least one of R ^1" to R ^3" is an aryl group, and at least one of R ^5" and R ^6" is an aryl group]

In the formula (b-1), R ^1" to R ^3" are each independently an aryl group or an alkyl group; and at least one of R ^1" to R ^3" is an aryl group. It is preferable that two or more of R ^{1 "} to R ^{3 "} are aryl groups, and those in which R ^1" to R ^{3" are} all aryl groups are preferred.

The aryl group of R ^1" to R ^3" is not particularly limited, and is, for example, an aryl group having 6 to 20 carbon atoms, and at least one or all of hydrogen atoms of the aryl group may be alkyl group, alkoxy group, A halogen atom or the like may be substituted or unsubstituted. From the viewpoint of inexpensive synthesis of an aryl group, it is preferred to use an aryl group having 6 to 10 carbon atoms. Specifically, for example, a phenyl group, a naphthyl group or the like.

The alkyl group which may substitute the hydrogen atom of the above aryl group is preferably an alkyl group having 1 to 5 carbon atoms, and more preferably a methyl group, an ethyl group, a propyl group, an n-butyl group or a tert-butyl group.

The alkoxy group which may be substituted for the hydrogen atom of the above aryl group is preferably an alkoxy group having 1 to 5 carbon atoms, and more preferably a methoxy group or an ethoxy group. The halogen atom which may substitute the hydrogen atom of the above aryl group is preferably a fluorine atom.

The alkyl group of R ^1" to R ^3" is not particularly limited, and may, for example, be a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms. From the viewpoint of excellent resolution, etc., it is preferred that the carbon number is from 1 to 5. Specifically, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, cyclopentyl, hexyl, cyclohexyl, decyl, decyl, and the like, From the viewpoint of having excellent resolution and being inexpensively synthesized, it is more preferable to use a methyl group.

Among them, those in which R ^{1 "} to R ^{3 "} are each a phenyl group or a naphthyl group are preferred.

R ^4" is a linear, branched or cyclic alkyl group, or a linear, branched or cyclic fluorinated alkyl group.

The linear or branched alkyl group is preferably a carbon number of 1 to 10, more preferably a carbon number of 1 to 8, and most preferably a carbon number of 1 to 4.

The cyclic alkyl group is a cyclic group represented by the above R ^{1 "} , preferably having a carbon number of 4 to 15, preferably 4 to 10 carbon atoms, and most preferably having 6 to 10 carbon atoms. good.

The linear or branched fluorinated alkyl group is preferably a carbon number of 1 to 10, more preferably a carbon number of 1 to 8, and most preferably a carbon number of 1 to 4.

The cyclic fluorinated alkyl group is a cyclic group represented by the above R ^{1 "} , preferably having a carbon number of 4 to 15, preferably a carbon number of 4 to 10, and a carbon number of 6 to 10. For the best.

Further, the fluorination ratio of the fluorinated alkyl group (the ratio of the fluorine atom in the alkyl group) is preferably from 10 to 100%, more preferably from 50 to 100%, and particularly, the hydrogen atom is replaced by a fluorine atom, The strength of the acid is stronger and better. R ^{4" is} preferably a linear or cyclic alkyl group or a linear or cyclic fluorinated alkyl group.

In the formula (b-2), R ^5" to R ^6" are each independently an aryl group or an alkyl group; at least one of R ^5" to R ^6" is an aryl group, and all of R ^5" to R ^6" are The aryl group is the best.

The aryl group of R ^5" and R ^6" is, for example, the same group as the aryl group of R ^1" to R ^3" .

The alkyl group of R ^5" and R ^6" is, for example, the same group as the alkyl group of R ^1" to R ^3" .

Among them, it is preferred that all of R ^5" and R ^6" are phenyl groups.

(B-2) in the above formula R ^{4 "and} (b-1) in the R ^4" is the same as the contents.

Specific examples of the sulfonium acid generators represented by the formulae (b-1) and (b-2), for example, diphenyl iodonium trifluoromethanesulfonate or nonafluorobutane sulfonate, bis (4-tert) -butylphenyl)iodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, triphenylsulfonium trifluoromethanesulfonate, heptafluoropropanesulfonate or its nonafluorobutanesulfonate , tris(4-methylphenyl)phosphonium trifluoromethanesulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, dimethyl(4-hydroxynaphthyl)phosphonium trifluoromethanesulfonate Acid ester, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, triphenylmethanesulfonate of monophenyldimethylhydrazine, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, diphenyl Trifluoromethanesulfonate of monomethylhydrazine, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, trifluoromethanesulfonate of (4-methylphenyl)diphenylphosphonium, and heptafluoropropane a sulfonate or a nonafluorobutanesulfonate thereof, a (4-methoxyphenyl)diphenylphosphonium trifluoromethanesulfonate, a heptafluoropropanesulfonate or a nonafluorobutanesulfonate thereof, (4-tert-butyl)phenylphosphonium trifluoromethane a sulfonate, a heptafluoropropane sulfonate or a nonafluorobutane sulfonate thereof, a triphenylmethanesulfonate of diphenyl(1-(4-methoxy)naphthyl)anthracene, or a heptafluoropropane sulfonate thereof or A nonafluorobutane sulfonate, a trifluoromethanesulfonate of bis(1-naphthyl)phenylhydrazine, a heptafluoropropane sulfonate or a nonafluorobutanesulfonate thereof. Further, as the anion portion of the onium salt, an onium salt substituted with a methanesulfonate, n-propanesulfonate, n-butanesulfonate or n-octanesulfonate can be used.

Further, in the above formula (b-1) or (b-2), the anthracene salt-based acid generator obtained by substituting an anion moiety with an anion moiety represented by the following formula (b-3) or (b-4) can also be used. (The cationic moiety is the same as the above formula (b-1) or (b-2)).

In the present specification, the oxime sulfonate-based acid generator has, for example, a compound having at least one group represented by the following formula (B-1), which has a property of generating an acid by radiation irradiation. The above-mentioned oxime sulfonate-based acid generator is often used for reinforcing a chemical-type positive-type resist composition, and the present invention can be arbitrarily selected and used.

(In the formula (B-1), R ³¹ and R ³² are each independently an organic group)

The organic group of R ³¹ and R ³² is a group containing a carbon atom, but it may also contain an atom other than a carbon atom (for example, a hydrogen atom, an oxygen atom, a nitrogen atom, a sulfur atom, a halogen atom (a fluorine atom, a chlorine atom, etc.), etc.) ).

The organic group of R ³¹ is preferably a linear, branched or cyclic alkyl group or an aryl group. The aforementioned alkyl group or aryl group may have a substituent. The substituent is not limited in any way, and may be, for example, a fluorine atom, a linear one having a carbon number of 1 to 6, a branched or a cyclic alkyl group or the like. Here, the "having a substituent" means that at least one of the hydrogen atoms of the alkyl group or the aryl group is substituted with a substituent.

The alkyl group is preferably a carbon number of 1 to 20, preferably a carbon number of 1 to 10, more preferably a carbon number of 1 to 8, a carbon number of 1 to 6 or a carbon number of 1 to 4. . The alkyl group is particularly preferably a halogenated alkyl group in which at least one hydrogen atom is substituted by a halogen atom. More preferably, the halogenated alkyl group obtained by substituting all hydrogen atoms with a halogen atom. The halogen atom, for example, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom or the like, is preferably a fluorine atom. That is, the halogenated alkyl group is preferably a fluorinated alkyl group.

The aryl group is preferably a carbon number of 4 to 20, preferably a carbon number of 4 to 10, and more preferably a carbon number of 6 to 10. The aryl group is particularly preferably a halogenated aryl group in which at least one hydrogen atom is substituted by a halogen atom. More preferably, the halogenated aryl group obtained by substituting all hydrogen atoms with a halogen atom. The halogen atom, for example, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom or the like, is preferably a fluorine atom.

R ^{31 is} particularly preferably an alkyl group having 1 to 4 carbon atoms or a fluorinated alkyl group having 1 to 4 carbon atoms which has no substituent.

The organic group of R ³² is preferably a linear, branched or cyclic alkyl group, an aryl group or a cyano group. The alkyl group or the aryl group of R ³² is, for example, the same as the alkyl group or the aryl group exemplified in the above R ³¹ .

R ^{32 is} particularly preferably a cyano group, an alkyl group having 1 to 8 carbon atoms which has no substituent, or a fluorinated alkyl group having 1 to 8 carbon atoms.

The oxime sulfonate-based acid generator is more preferably a compound represented by the following formula (B-2) or (B-3).

[In the formula (B-2), R ³³ is a cyano group, an alkyl group having no substituent or an alkyl halide; R ³⁴ is an aryl group; and R ³⁵ is an alkyl group having no substituent or an alkyl halide;

[In the formula (B-3), R ³⁶ is a cyano group, an alkyl group having no substituent or a halogenated alkyl group; R ³⁷ is a 2 or 3 valent aromatic hydrocarbon group; and R ³⁸ is an alkyl group having no substituent or Halogenated alkyl group, p" is 2 or 3]

In the above formula (B-2), the alkyl group or the halogenated alkyl group having no substituent of R ³³ is preferably a carbon number of 1 to 10, more preferably a carbon number of 1 to 8, and a carbon number of 1 to 6. optimal. A halogen atom in the above halogenated alkyl group, for example, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom or the like.

R ³³ is preferably a halogenated alkyl group, more preferably a fluorinated alkyl group.

The fluorinated alkyl group in R ³³ is preferably one in which the hydrogen atom in the alkyl group is fluorinated by 50% or more, more preferably 70% or more, and more preferably 90% or more.

The aryl group of R ³⁴ , for example, a ring of an aromatic hydrocarbon such as a phenyl group or a biphenyl group, a fluorenyl group, a naphthyl group, an anthracyl group or a phenanthroline group, removes one hydrogen atom. And a heteroaryl group obtained by substituting a part of a carbon atom constituting the ring of the above-mentioned group with a hetero atom such as an oxygen atom, a sulfur atom or a nitrogen atom. Among them, the base is better.

The aryl group of R ³⁴ may have a substituent such as an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group or an alkoxy group. A halogen atom in the above halogenated alkyl group, for example, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom or the like. The alkyl group or the halogenated alkyl group in the substituent is preferably a carbon number of 1 to 8, more preferably a carbon number of 1 to 4. Further, the halogenated alkyl group is more preferably a fluorinated alkyl group. The alkoxy group in the substituent is preferably a carbon number of 1 to 5.

The alkyl group or the halogenated alkyl group having no substituent of R ³⁵ is preferably a carbon number of 1 to 10, more preferably a carbon number of 1 to 8, and most preferably a carbon number of 1 to 6. A halogen atom in the above halogenated alkyl group, for example, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom or the like.

R ³⁵ is preferably a halogenated alkyl group, more preferably a fluorinated alkyl group.

The fluorinated alkyl group in R ³⁵ preferably has a hydrogen atom in the alkyl group of 50% or more, more preferably 70% or more, and when it is fluorinated by 90% or more, the acid produced can be increased. For better. The most preferred is a perfluorinated alkyl group in which the hydrogen atom is 100% replaced by fluorine.

In the above formula (B-3), the alkyl group or the halogenated alkyl group having no substituent of R ³⁶ is, for example, the same as the alkyl group or the halogenated alkyl group having no substituent represented by the above R ³³ .

The 2 or 3 valent aromatic hydrocarbon group of R ³⁷ is, for example, a group obtained by further removing 1 or 2 hydrogen atoms from the aryl group of the above R ³⁴ .

The alkyl group or the halogenated alkyl group having no substituent of R ³⁸ is, for example, the same as the alkyl group or halogenated alkyl group having no substituent represented by the above R ³⁵ .

p" is preferably 2.

Specific examples of the sulfonate-based acid generator, such as α-(p-toluenesulfonyloxyimido)-benzyl cyanide (cyanide), α-(p-chlorophenylsulfonyloxyimino) -benzyl cyanide, α-(4-nitrophenylsulfonyloxyimido)-benzyl cyanide, α-(4-nitro-2-trifluoromethylbenzenesulfonyloxyimido)- Benzyl cyanide, α-(phenylsulfonyloxyimido)-4-chlorobenzyl cyanide, α-(phenylsulfonyloxyimido)-2,4-dichlorobenzyl cyanide, --(phenylsulfonyloxyimino)-2,6-dichlorobenzyl cyanide, α-(phenylsulfonyloxyimino)-4-methoxybenzyl cyanide, α-(2 -Chlorobenzenesulfonyloxyimido)-4-methoxybenzyl cyanide, α-(phenylsulfonyloxyimino)-thien-2-ylacetonitrile, α-(4-dodecane Benzosulfonyloxyimido)-benzyl cyanide, α-[(p-toluenesulfonyloxyimino)-4-methoxyphenyl]acetonitrile, α-[(dodecylbenzenesulfonate)醯 亚 imino)-4-methoxyphenyl]acetonitrile, α-(p-toluenesulfonyloxyimino)-4-thyl cyanide, α-(methylsulfonyloxyimino) -1-cyclopentene Acetonitrile, α-(methylsulfonyloxyimino)-1-cyclohexenylacetonitrile, α-(methylsulfonyloxyimino)-1-cycloheptenylacetonitrile, α-(methylsulfonate醯 oxyimino)-1-cyclooctenylacetonitrile, α-(trifluoromethylsulfonyloxyimino)-1-cyclopentenylacetonitrile, α-(trifluoromethylsulfonyloxyimine -cyclohexylacetonitrile, α-(ethylsulfonyloxyimino)-ethylacetonitrile, α-(propylsulfonyloxyimino)-propylacetonitrile, α-(cyclohexylsulfonate) Amino)-cyclopentylacetonitrile, α-(cyclohexylsulfonyloxyimino)-cyclohexylacetonitrile, α-(cyclohexylsulfonyloxyimino)-1-cyclopentenylacetonitrile, α-( Ethylsulfonyloxyimido)-1-cyclopentenylacetonitrile, α-(isopropylsulfonyloxyimino)-1-cyclopentenylacetonitrile, α-(n-butylsulfonyloxy) Imino)-1-cyclopentenylacetonitrile, α-(ethylsulfonyloxyimino)-1-cyclohexenylacetonitrile, α-(isopropylsulfonyloxyimino)-1- Cyclohexenylacetonitrile, α-(n-butylsulfonyloxyimino)-1-cyclohexenylacetonitrile, α-(methylsulfonyloxyimino)-phenylacetonitrile, α (Methylsulfonyloxyimido)-p-methoxyphenylacetonitrile, α-(trifluoromethylsulfonyloxyimino)-phenylacetonitrile, α-(trifluoromethylsulfonate Amino)-p-methoxyphenylacetonitrile, α-(ethylsulfonyloxyimido)-p-methoxyphenylacetonitrile, α-(propylsulfonyloxyimino)-p- Methylphenylacetonitrile, α-(methylsulfonyloxyimido)-p-bromophenylacetonitrile, and the like.

Further, the oxime sulfonate-based acid generator disclosed in JP-A-9-208554 (paragraphs [0012] to [0014] [Chem. 18] to [Chem. 19]), International Publication No. 04/074242 ( The sulfonate-based acid generator disclosed in Examples 1 to 40) on pages 65 to 85 may also be used in combination.

Further, for example, a compound shown below or the like is suitable.

Among the above exemplified compounds, the following four compounds are more preferable.

Specific examples of the dialkyl or bisarylsulfonyldiazomethane in the diazomethane acid generator, such as bis(isopropylsulfonyl)diazomethane or bis(p-toluenesulfonyl) Diazomethane, bis(1,1-dimethylethylsulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane, bis(2,4-dimethylphenylsulfonyl) Diazomethane, etc.

Further, the diazomethane-based acid generator disclosed in JP-A-H11-035551, JP-A-H11-035552, and JP-A-11-035573 is also suitable.

Further, poly(disulfonyl)diazomethane, for example, 1,3-bis(phenylsulfonyldiazomethylsulfonyl)propane disclosed in JP-A-11-322707, 1,4- Bis(phenylsulfonyldiazomethylsulfonyl)butane, 1,6-bis(phenylsulfonyldiazomethylsulfonyl)hexane, 1,10-bis(phenylsulfonate) Base heavy nitrogen methylsulfonyl) decane, 1,2-bis(cyclohexylsulfonyldiazomethylsulfonyl)ethane, 1,3-bis(cyclohexylsulfonyldiazomethylsulfonate) Mercapto)propane, 1,6-bis(cyclohexylsulfonyldiazomethylsulfonyl)hexane, 1,10-bis(cyclohexylsulfonyldiazomethylsulfonyl)decane, and the like.

(B2) The component may be used alone or in combination of two or more.

In the resist composition for immersion exposure of the present invention, the content of the component (B) is from 0.5 to 30 parts by mass, preferably from 1 to 20 parts by mass, per 100 parts by mass of the component (A). In the above range, the pattern can be sufficiently formed. And a uniform solution can be obtained with good preservation stability.

<(D) ingredient>

In the positive-type photoresist composition for immersion exposure of the present invention, in the case of post exposure stability of the latent image formed by the pattern-wise exposure of the resist layer Further, a nitrogen-containing organic compound (D) of any component (hereinafter also referred to as (D) component) may be further added.

As the component (D), proposals have been made for various compounds, and any of the known components may be used, and among them, an aliphatic amine, particularly a secondary aliphatic amine or a tertiary aliphatic amine is preferred. In the specification and the patent application of the present invention, the "aliphatic" is a concept relating to aromaticity, that is, it is defined as a group or a compound having no aromaticity.

The "aliphatic cyclic group" is defined as a monocyclic group or a polycyclic group having no aromaticity.

Aliphatic amines, such as ammonia NH ₃ in the at least one hydrogen atom is 12 or less carbon atoms of alkyl or hydroxyalkyl substituents of the resulting amine (alkylamine or alkanolamine) or a cyclic amine.

Specific alkylamines and alkanolamines such as n-hexylamine, n-heptylamine, n-octylamine, n-decylamine, n-decylamine, etc.; monoethylamine; a dialkylamine such as -n-propylamine, di-n-heptylamine, di-n-octylamine or dicyclohexylamine; trimethylamine, triethylamine, tri-n-propylamine , tri-n-butylamine, tri-n-hexylamine, tri-n-pentylamine, tri-n-heptylamine, tri-n-octylamine, tri-n-decylamine, tri- a trialkylamine such as n-decylamine or tri-n-dodecylamine; diethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine, di-n-octanolamine, tri-n An alkanolamine such as an octanolamine. Among them, a trialkylamine having 5 to 10 carbon atoms is preferred, and a tri-n-pentylamine or a tri-n-octylamine is more preferred, and a tri-n-pentylamine is preferred.

The cyclic amine is, for example, a heterocyclic compound containing a nitrogen atom as a hetero atom. The heterocyclic compound may be a monocyclic compound (aliphatic monocyclic amine) or a polycyclic compound (aliphatic polycyclic amine).

Aliphatic monocyclic amines, in particular, for example, piperidine, piperidine Wait.

The aliphatic polycyclic amine is preferably a carbon number of 6 to 10, specifically, for example, 1,5-diazabicyclo[4.3.0]-5-nonene, 1,8-diaza Ring [5.4.0]-7-undecene, hexamethylenetetrazole, 1,4-diazabicyclo[2.2.2]octane, and the like.

They may be used alone or in combination of two or more.

(D) The component (A) component is 100 parts by mass, and is usually used in the range of 0.01 to 5.0 parts by mass.

<arbitrary ingredients>

Further, the positive-type photoresist composition for immersion exposure of the present invention is used for preventing deterioration of sensitivity, or for improving the shape of the photoresist pattern and the post exposure stability of the latent image formed by the For the purpose of pattern-wise exposure of the resist layer, etc., at least one compound (E) selected from the group consisting of an organic carboxylic acid of any composition or an oxyacid of phosphorus or a derivative thereof may be further added (hereinafter also referred to as For (E) ingredients).

An organic carboxylic acid such as acetic acid, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid or the like is preferred.

Phosphorus oxyacids such as phosphoric acid, Phosphonic acid, Phosphinic acid, etc., wherein phosphonic acid is preferred.

The oxo acid derivative of phosphoric acid is, for example, an ester group obtained by substituting a hydrogen atom of the oxo acid with a hydrocarbon group, and the hydrocarbon group is, for example, an alkyl group having 1 to 5 carbon atoms or an aryl group having 6 to 15 carbon atoms.

The phosphoric acid derivative is, for example, a phosphate such as di-n-butyl phosphate or diphenyl phosphate.

Phosphonic acid derivatives such as chromic acid esters such as dimethyl phosphonate, di-n-butyl phosphonate, phenylphosphonic acid, diphenyl phosphonate, dibenzyl phosphonate, and the like.

Phosphinic acid derivatives such as phosphinates such as phenylphosphinic acid.

(E) The components may be used singly or in combination of two or more.

The component (E) is preferably an organic carboxylic acid, particularly salicylic acid.

The component (E) is generally used in an amount of from 0.01 to 5.0 parts by mass per 100 parts by mass of the component (A).

The photoresist composition for immersion exposure of the present invention can be further blended with an additive which is suitable for mixing, for example, an additive resin which can improve the properties of the photoresist film, a surfactant for improving coating properties, a dissolution inhibitor, and a plasticizer. Agents, stabilizers, colorants, halo inhibitors, dyes, and the like.

The photoresist composition for immersion exposure of the present invention can be produced by dissolving a material in an organic solvent (hereinafter also referred to as (S) component).

The component (S) can be used as long as it can dissolve the components to be used, and a suitable solution can be used. For example, one or two or more kinds of the above-mentioned conventionally used solvents can be used.

For example, lactones such as γ-butyrolactone, ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl-n-pentanone, methyl isoamyl ketone, and 2-heptanone; ethylene glycol, Polyols such as ethylene glycol, propylene glycol, dipropylene glycol and derivatives thereof; esters of ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate, or dipropylene glycol monoacetate a compound to be bonded; an ether having a monoalkyl ether or a monophenyl ether such as a monomethyl ether, a monoethyl ether, a monopropyl ether or a monobutyl ether as described above or a compound having an ester bond; a derivative of a polyol such as a bonded compound; wherein propylene glycol monomethyl ether acetate (PGMEA) or propylene glycol monomethyl ether (PGME) is preferred; a cyclic ether such as dioxane; Or methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxy propionate, etc. Esters; anisole, ethylbenzyl ether, cresyl methyl ether, diphenyl ether, dibenzyl ether, phenylethyl ether, butylphenyl ether, ethylbenzene, diethylbenzene, pentylbenzene Cumene, toluene, xylene, cumene, mesitylene and the like, aromatic organic solvents.

The organic solvent may be used singly or in the form of a mixture of two or more.

Further, among them, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), EL, γ-butyrolactone are preferably used.

Further, a mixed solvent obtained by mixing PGMEA with a polar solvent is preferred, and the addition ratio (mass ratio) may be appropriately determined depending on the compatibility of PGMEA with a polar solvent, etc., preferably from 1:9 to 9:1. More preferably, it is in the range of 2:8 to 8:2.

More specifically, when the polar solvent is ethyl lactate (EL), the mass of PGMEA:EL is preferably from 1:9 to 9:1, more preferably from 2:8 to 8:2. When the polar solvent is PGME, the mass of PGMEA:PGME is preferably from 1:9 to 9:1, more preferably from 2:8 to 8:2, most preferably from 3:7 to 7:3.

Further, among the components (S), for example, a mixed solvent of at least one selected from PGMEA and EL and γ-butyrolactone is preferably used. At this time, in the mixing ratio, the former and the latter are preferably 70:30 to 95:5.

Further, the (S) component is preferably a mixed solvent obtained by using a mixed solvent of the above PGMEA and PGME and γ-butyrolactone.

The amount of the component (S) is not particularly limited. Generally, it can be appropriately selected in accordance with the concentration applied to the substrate, the thickness of the coating film, etc., and the solid concentration in the photoresist composition is generally 2 to 20 It is used in the range of % by mass, preferably 5 to 15% by mass.

In the photoresist composition for immersion exposure of the present invention, good lithographic etching characteristics can be obtained even when a photoresist pattern having a top coat film is formed on the photoresist film.

The reason for the above is still unclear, but it is presumed that the acid generator (B1) represented by the above formula (b1-1) used in the present invention is in the exposure wavelength band (particularly, the wavelength region of the ArF excimer laser). The effect of light can be effectively suppressed. Therefore, when the component (B1) is added to the resist composition for immersion exposure of the present invention, the light absorption can be suppressed and the transparency of the photoresist composition can be improved.

Further, since the (B1) component has good dispersibility in the photoresist film, a more uniform distribution can be obtained in the photoresist film as compared with the conventional acid generator. Therefore, when an acid which causes the component (B1) to be generated by exposure is used, it is presumed that a more uniform diffusion can be obtained in the photoresist film as compared with the case of using a conventional acid generator.

For the above reasons, it is known that the photoresist composition for immersion exposure of the present invention can obtain good lithographic etching characteristics even when a photoresist pattern having a top coat film is formed on the photoresist film.

The immersion exposure photoresist composition of the present invention can be formed, for example, to have a good line width uniformity (LWR), a photoresist pattern shape (especially a surface roughness of a photoresist pattern), and a mask error factor. , MEF), exposure latitude (EL latitude) and other lithography characteristics of the photoresist pattern.

Moreover, the MEF is a parameter that can faithfully reproduce the reticle pattern of different sizes when the reticle size (line width and space width) is changed under the same exposure amount and at a fixed pitch, and the MEF is more The closer to one, the higher the reproducibility of the mask.

The EL latitude is a parameter of the amount of change in the dimensional change of the pattern displayed by the change in the amount of exposure, and the larger the value, the smaller the amount of change.

Method for forming photoresist pattern

Next, a method of forming a photoresist pattern of a second embodiment of the present invention will be described.

The method for forming a photoresist pattern of the present invention comprises the step of forming a photoresist film on a substrate by using the positive-type photoresist composition for immersion exposure according to the first embodiment of the present invention, and infiltrating the photoresist film. The step of exposing the photoresist to develop the photoresist film to form a photoresist pattern.

A preferred example of the method of forming the photoresist pattern of the present invention is as follows.

First, the positive-type photoresist composition for immersion exposure of the present invention is applied onto a substrate such as a wafer by a spin coater or the like, and then subjected to a post-bake (PAB) treatment. After that, a photoresist film can be formed.

At this time, an organic or inorganic antireflection film may be provided between the substrate and the coating layer of the positive resist composition to form a two-layer laminate.

Further, an organic anti-reflection film may be further provided on the photoresist film to form a two-layer laminate, or an anti-reflection film may be provided on the lower layer to form a three-layer laminate.

The top coat film is not particularly limited, and it can be used as usual for immersion exposure. For example, the protective film disclosed in the specification of International Publication No. 05/019937 and International Publication No. 04/074937 contains -Q-NH-SO ₂ -R ⁵ (wherein Q is a linear chain having a carbon number of 1 to 5 or a main chain cyclic type resin in which a branched chain alkyl group, R ⁵ is a fluorinated alkyl group, and -CO-O-R ⁷ (wherein R ⁷ is a fluorinated alkyl group) is dissolved in an organic group. A protective film or the like formed of a composition obtained by a solvent (an alcohol solvent such as isobutanol).

Here, the "main chain annular type resin" means that the structural unit constituting the resin has a single ring or a polycyclic ring structure, and at least one, preferably two or more rings on the ring structure. The carbon atom is a structural unit constituting the main chain (hereinafter referred to as "main chain cyclic type structural unit").

The main chain cyclic structural unit is, for example, a structural unit derived from a polycyclic olefin (polycyclic olefin), a structural unit containing a dicarboxylic anhydride, and the like. Further, it is preferred that the main chain has a structural unit derived from a polycycloolefin (polycyclic olefin, preferably raw spinel, etc.).

The top coat film disposed on the photoresist film is preferably one which is soluble in an alkali developer.

The steps so far can be carried out using a known method. The operating conditions and the like are preferably set in accordance with the composition content or characteristics of the photoresist composition for immersion exposure to be used.

Next, the photoresist film obtained by the above method is subjected to liquid immersion exposure (Liquid Immersion Lithography) through a desired mask pattern. In this case, the photoresist (infiltrating medium) having a refractive index higher than that of air may be filled between the photoresist film (or the top coating film) and the lens at the lowest position of the exposure device in advance, and in this state. Exposure is performed under (immersion exposure).

The wavelength used for the exposure is not particularly limited, and it can be carried out using radiation such as ArF excimer laser, KrF excimer laser, or F ₂ laser. The positive photoresist composition of the present invention is effective for KrF or ArF excimer lasers, particularly ArF excimer lasers.

As described above, in the forming method of the present invention, when exposed, the photoresist film (or the top coating film) and the lowermost position of the exposure device are filled with the infiltrating medium between the lenses, and exposure is performed in this state ( Infiltrating exposure).

In this case, the immersion medium is preferably a solvent having a refractive index larger than that of air and smaller than a refractive index of the photoresist film formed by using the positive-type resist composition for immersion exposure. The refractive index of the solvent is not particularly limited as long as it is within the above range.

A solvent having a refractive index greater than that of air and smaller than the refractive index of the photoresist film, for example, water, a fluorine-based inert liquid, an oxime-based solvent, or the like.

Specific examples of the fluorine-based inert liquid include a liquid such as C ₃ HC ₁₂ F ₅ , C ₄ F ₉ OCH ₃ , C ₄ F ₉ OC ₂ H ₅ , C ₅ H ₃ F ₇ or the like as a main component, and a boiling point It is preferably from 70 to 180 ° C, and more preferably from 80 to 160 ° C. In the fluorine-based inert liquid, when the boiling point is within the above range, the medium used for the wetting type can be removed by a simple method after the completion of the exposure, and is preferable.

The fluorine-based inert liquid is particularly preferably a perfluoroalkyl compound obtained by substituting all hydrogen atoms in the alkyl group with fluorine atoms. The perfluoroalkyl compound is specifically, for example, a perfluoroalkyl ether compound or a perfluoroalkylamine compound.

Further, specifically, the perfluoroalkyl ether compound is, for example, perfluoro(2-butyl-tetrahydrofuran) (boiling point: 102 ° C), and the perfluoroalkylamine compound, for example, perfluorotributylamine (boiling point: 174 ° C) )Wait.

The positive-type resist composition for immersion exposure of the present invention is particularly susceptible to the adverse effects of water, and has an excellent refractive index and a shape of a resist pattern, and has a refractive index higher than that of air. A solvent having a refractive index of a large refractive index is preferably water. Moreover, water is also preferable in terms of cost, safety, environmental and extensive use.

Next, after the end of the immersion exposure step, post exposure bake (PEB) is performed, followed by development treatment using an alkali developer formed of an alkaline aqueous solution. Subsequently, it is preferred to use pure water for water washing. In the case of water washing, for example, water droplets may be sprayed or sprayed on the surface of the substrate to be rotated, and the developer on the substrate and the positive-type photoresist composition for immersion exposure dissolved in the developer may be washed away. Subsequently, drying is carried out, and the photoresist film (coating film of the positive-type resist composition for immersion exposure) is drawn in accordance with the shape of the reticle pattern to obtain a photoresist pattern.

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

<Resin component (A)>

The polymer (A)-1 of the component (A) used in the examples and the comparative examples is as follows.

Here, the mass average molecular weight (Mw) and the degree of dispersion (Mw/Mn) of the following polymer (A)-1 are collectively described. The mass average molecular weight (Mw) and the degree of dispersion (Mw/Mn) were determined by gel permeation chromatography (GPC) on a polystyrene basis.

Further, the composition ratio was calculated by carbon NMR. In the chemical formula, the number listed in the lower right of the structural unit is the ratio (mol%) of each structural unit in the polymer.

(Mw: 10000, Mw/Mn: 2.0; monomers derived from each structural unit are synthesized by a known dropping polymerization method)

<Production of positive resist composition solution for immersion exposure> (Examples 1 to 2, Comparative Examples 1 to 2)

Each component shown in Table 1 was mixed and dissolved to prepare a positive-type resist composition solution for immersion exposure. Also, the "-" in the table means no addition.

Each of the abbreviations in Table 1 has the following meanings. Further, the value in [] is the added amount (parts by mass).

(B)-1: an acid generator represented by the following chemical formula (b1-01).

(B)-2: Di(1-naphthyl)phenylphosphonium hexafluorobutanesulfonate.

(B)-3: Triphenylsulfonium nonafluorobutanesulfonate.

(B)-4: (4-methylphenyl)diphenylphosphonium trifluoromethanesulfonate.

(D)-1: Tri-n-pentylamine.

(D)-2: Triethanolamine.

(E)-1: Salicylic acid.

(S)-1: γ-butyrolactone.

(S)-2: a mixed solvent of PGMEA/PGME=6/4 (mass ratio).

<Evaluation of lithography etching characteristics>

A resist pattern was formed using the resulting immersion exposure positive resist composition, and the following lithographic etching characteristics were evaluated.

Further, the lithographic etching characteristics were evaluated on the photoresist film, respectively, in the case where the top coat film was not provided (Examples 1 to 2, Comparative Examples 1 to 2), and the top coat film was provided. The photoresist pattern formed in the case (Example 1, Comparative Example 1) was evaluated.

The results of the case where the top coat film was not provided are shown in Table 2, and the results obtained by providing the top coat film are shown in Table 3.

[Formation of photoresist pattern]

The organic anti-reflection film composition "ARC-29A" (manufactured by Privah Technology Co., Ltd.) was applied to a ruthenium wafer of 8 inches on a wafer, and was 205 ° C, 60 on a hot plate. After baking and drying under the conditions of seconds, an organic anti-reflection film having a film thickness of 77 nm was formed. Subsequently, the positive-type resist composition solution for immersion exposure obtained above is uniformly applied to the anti-reflection film by using a spin coater, and is applied to the hot plate at temperatures shown in Table 2 and Table 3, respectively. The pre-baking (PAB) treatment was carried out for 60 seconds, and after drying, a photoresist film having a film thickness of 150 nm was formed.

Next, in the case where the top coat film is provided, the coating liquid 1 for forming a protective film is applied onto the resist film using a spin coater, and heat-treated at 90 ° C for 60 seconds. A top coat film having a film thickness of 35 nm was formed.

In addition, the "coating liquid 1 for forming a protective film" is a composition obtained by dissolving a resin having a structural unit derived from a raw material of a sulfonylamino group, which is represented by the following chemical formula, in isobutanol (solid) The concentration of the component is 4% by mass).

(Mw=5000, Mw/Mn=1.5; manufactured by PROMERUS)

Next, an ArF excimer laser (193 nm) was selectively irradiated through a reticle pattern using an ArF exposure apparatus NSR-S302 (manufactured by Ricoh Co., Ltd.; NA (number of openings) = 0.60, 2/3 wheel illumination). Subsequently, according to the temperatures shown in Table 2 and Table 3, the post-exposure heating (PEB) treatment was carried out under heating conditions for 60 seconds, and at 23 ° C, a 2.38 mass% aqueous solution of tetramethylammonium hydroxide (TMAH) was used. The development was carried out under conditions of 30 seconds, and then washed with pure water for 30 seconds, and dried by vibration. As a result, a line-space (1:1) photoresist pattern (L/S pattern) is formed, and the optimum exposure amount of the L/S pattern having a line width of 120 nm and a pitch of 240 nm is formed (sensitivity: Eop) , mJ/cm ² ).

[Line width uniformity (LWR)]

For the line width of the L/S pattern with a line width of 120 nm and a pitch of 240 nm formed by the above Eop, a length measuring SEM (manufactured by Hitachi, Ltd., trade name: S-9220) was used, and 5 points were measured in accordance with the length of the line width. From the result, the three-fold value (3 s) of the standard deviation (s) was calculated as the LWR scale. The results are shown in Tables 2 and 3.

Further, the smaller the value of the 3s is, the smaller the unevenness of the line width is, and the one having the uniform width is obtained.

As is apparent from the results of Table 2, in the case where the top coat film was not provided, the examples 1 and 2 of the present invention showed a smaller LWR value when compared with Comparative Example 2, and it was confirmed that the width was more uniform. Photoresist pattern. Further, the LWR value of Example 1 was confirmed to be equal to Comparative Example 1.

As is apparent from the results of Table 3, in the case where the top coat film was provided, Example 1 of the present invention showed a smaller LWR value when compared with Comparative Example 1, and confirmed that a more uniform width resist was obtained. Graphic type.

From the results of Tables 2 and 3, in the first embodiment of the present invention, the LWR value in the top coating film is set to be smaller when compared with the LWR value in which the top coating film is not provided, and it is confirmed that the top coating is provided. In the case of a membrane, LWR can be suppressed.

Further, in Comparative Example 1, in the case where the top coat film was provided, the LWR value was large, and it was confirmed that the provision of the top coat film caused deterioration of the LWR.

Further, the surface shape of the resist pattern in the case where the top coat film was formed was observed by a scanning electron microscope (SEM), and the photoresist pattern of Example 1 of the present invention was compared with Comparative Example 1. The surface roughness of the type is small.

Further, in the mask error factor (MEF) and the exposure latitude (EL latitude), the same as the LWR, and the case where the top coating film is not provided (Examples 1 to 2, Comparative Examples 1 and 2), The results of the evaluation of the photoresist patterns formed in the case of the top coating film (Example 1, Comparative Example 1) were carried out, and the examples 1 and 2 of the present invention were confirmed, respectively, when compared with the comparative examples 1 and 2, respectively. Have the same degree.

From the above results, it was confirmed that the first embodiment of the present invention can obtain good lithographic etching characteristics even when a photoresist pattern in which a top coat is provided on the photoresist film.

The present invention provides a photoresist composition for immersion exposure and a method for forming a photoresist pattern which can obtain good lithographic etching characteristics even when a photoresist pattern having a top coating film is formed on a photoresist film. . Therefore, the present invention is extremely industrially usable.

Claims (9)

A immersion exposure photoresist composition comprising: (A) a resin component which changes an alkali solubility by an action of an acid, and (B) an immersion exposure light which generates an acid generator component by exposure to an acid The composition of the acid generator (B) is an acid generator (B1) containing a cation portion represented by the following formula (b1-1), and (B) is a component (B1) The content of the component is 70% by mass or more, [wherein, R ⁴² and R ⁴³ are each independently an alkyl group, an alkoxy group or a hydroxyl group, and n ² and n ³ are each independently an integer of 0 to 2]. The photoresist composition for immersion exposure according to the first aspect of the invention, wherein the content of the acid generator (B1) is in the range of 1 to 30 parts by mass based on 100 parts by mass of the resin component (A). . The photoresist composition for immersion exposure according to the first or second aspect of the invention, wherein the resin component (A) is a resin component (A1) which increases alkali solubility by an action of an acid. Such as the immersion exposure photoresist composition of the third application patent scope The resin component (A1) is a structural unit (a1) derived from an acrylate having an acid-dissociable dissolution inhibiting group. The immersion exposure photoresist composition of claim 4, wherein the resin component (A1) further contains a structural unit (a2) derived from an acrylate having a lactone-containing cyclic group. The immersion exposure photoresist composition of claim 4, wherein the resin component (A1) further contains a structural unit (a3) derived from an acrylate having a polar group-containing aliphatic hydrocarbon group. The immersion exposure photoresist composition according to claim 5, wherein the resin component (A1) further contains a structural unit (a3) derived from an acrylate having a polar group-containing aliphatic hydrocarbon group. The immersion exposure photoresist composition of claim 1, which further contains a nitrogen-containing organic compound (D). A method for forming a photoresist pattern, comprising the step of forming a photoresist film on a substrate by using the photoresist composition for immersion exposure according to any one of claims 1 to 8 to cause the photoresist The step of film immersion exposure, the step of developing the photoresist film to form a photoresist pattern.