JP2005173463A - Photoresist composition and resist pattern forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoresist composition which improves the shape of a resist pattern, that is, rectangularity and line edge roughness while retaining high resolution. <P>SOLUTION: The photoresist composition contains (A) a polymer component including an alkali-soluble constitutional unit having an alicyclic group having both (i) a fluorine atom or a fluoroalkyl group and (ii) an alcoholic hydroxyl group, and having alkali solubility changed by the action of an acid; and (B) an acid generator component which generates an acid when it receives exposure light, and contains at least (B-1) an onium salt including a linear-fluoroalkylsulfonic acid ion as an anion moiety and (B-2) an onium salt including a sulfonic acid ion having a fluorine-unsubstituted heterocycle as an anion moiety. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a photoresist composition used for patterning of a semiconductor integrated circuit by lithography and a resist pattern forming method using the composition, and more specifically, resolution in fine patterning using exposure light of 200 nm or less. The present invention relates to a photoresist composition having improved resist characteristics such as pattern formability and a resist pattern forming method using the composition.

  As is well known, in lithography, a photoresist layer coated on a laminated semiconductor substrate is irradiated (exposed) with short wavelength light through a mask reflecting a negative or positive pattern of a semiconductor integrated circuit pattern to be realized. In this case, the photoresist composition used for the photoresist layer contains, as a main component, a photosensitive polymer that becomes insoluble (negative) or soluble (positive) in alkali in response to irradiation light. After the pattern light irradiation described above, heating (post exposure bake, hereinafter sometimes abbreviated as “PEB”) is performed to ensure the reaction of the resist layer by exposure, and subsequently, a portion that can be developed and dissolved is formed. By removing the photoresist pattern layer, a photoresist pattern layer accurately reflecting the circuit pattern to be realized is formed on the laminated semiconductor substrate. Thereafter, the patterned photoresist layer may be sufficiently cured by heating (post bake) to have resistance to etching in the next step. In the etching step, the surface layer or the upper layer of the laminated semiconductor substrate is dry-etched along the pattern using the patterned photoresist layer as a mask.

  Since the patterning of the semiconductor integrated circuit is performed through such steps, the first characteristic required for the photoresist composition is to obtain the characteristic of forming a fine pattern, that is, the resolution. Therefore, in lithography using ArF excimer laser light, a positive resist composition having excellent resolution and exposure margin has been proposed (see, for example, Patent Document 1).

By the way, research for obtaining a further ultrafine resist pattern is currently being conducted. In particular, lithography using an F ₂ excimer laser is attracting attention as a person who will bear future fine processing technology of 65 nm or less.

In the photoresist composition used for the F ₂ excimer laser beam which will be the next generation light source, the resolution is naturally required. In order to obtain the resolution, the pattern irradiation light reaches not only the surface portion of the resist layer but also the bottom surface portion on the substrate side, so that the irradiation layer can sufficiently expose the resist layer to the bottom surface portion. It is necessary to have “transparency with respect to”. That is, in order to obtain high resolution, high transparency is required at 157 nm, which is the main spectrum of F ₂ excimer laser light.

  Therefore, at present, in the technical field of providing a photoresist composition, by introducing fluorine (F), it is possible to ensure transparency to irradiation light having a wavelength of 157 nm as a main spectrum and to influence development characteristics after exposure. Development of a new polymer having resist performance such as solubility, pattern transfer resolution, and etching resistance is in progress.

JP 2002-341539 A

However, in the polymer into which the fluorine (F) is introduced, an onium salt having an anion moiety of a fluorinated alkyl sulfonate ion, which is known as an acid generator conventionally used in KrF or ArF resist compositions, is used alone. When a resist composition is prepared and exposed using an F ₂ excimer laser, a fine resist pattern can be formed, but the resist top portion is rounded or line edge roughness (LER) is generated. The shape of was insufficient.

  In addition, LER means the uneven unevenness | corrugation formed in the side wall of a line and space pattern, for example in the resist pattern after image development.

The present invention has been made in view of the above, and provides an unachieved technique of forming a fine pattern using exposure light of 200 nm or less, specifically, ArF excimer laser light and F ₂ excimer laser light. It is. That is, an object of the present invention is to provide a photoresist composition having improved resist pattern shape, that is, improved rectangularity and LER while maintaining high resolution.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by using a specific fluoropolymer in combination with a specific acid generator.

This invention is made | formed based on the said knowledge, ie, 1st invention of this invention has (A) (i) a fluorine atom or a fluorinated alkyl group, and (ii) both alcoholic hydroxyl groups. A polymer component containing an alkali-soluble structural unit having an aliphatic cyclic group, the alkali solubility being changed by the action of an acid, and (B) an acid generator component that generates an acid upon exposure to light, B-1) containing at least an onium salt having a linear fluoroalkyl sulfonate ion as an anion part, and (B-2) an onium salt having a sulfonate ion having a heterocyclic ring not substituted with fluorine as an anion part. A photoresist composition comprising an acid generator component.

  In the second invention of the present application, the photoresist composition is coated on a substrate to form a resist film, the resist film is selectively exposed, and then heated and developed to form the resist film on the substrate. A resist pattern forming method is characterized by forming a resist pattern.

  Disadvantages of using the present invention as a photoresist composition using a polymer containing fluorine (F) and an onium salt having a conventional fluorinated alkyl sulfonate ion as an anion alone, while maintaining high resolution. It is possible to improve the rectangularity and line edge roughness (LER) of the resist pattern.

Hereinafter, embodiments of the present invention will be described.
The polymer component (A) which is a base polymer in the photoresist composition of the present invention having the above-described structure comprises (i) an aliphatic cyclic group having both a fluorine atom or a fluorinated alkyl group and (ii) an alcoholic hydroxyl group. It is a polymer that contains an alkali-soluble structural unit (a1) and that changes its alkali solubility by the action of an acid. The polymer component (A) has an alkali-soluble structural unit (a1) having an aliphatic cyclic group having (i) a fluorine atom or a fluorinated alkyl group and (ii) an alcoholic hydroxyl group, and the action of an acid. The polymer is not limited as long as it is a polymer whose alkali solubility changes, but is preferably a polymer (positive type) component whose alkali solubility is increased by the action of an acid.

  The change in alkali solubility due to the action of an acid is a change in the polymer component in the exposed area, and if the alkali solubility increases in the exposed area, the exposed area becomes alkali-soluble, so it is used as a positive resist, On the other hand, if the alkali solubility in the exposed area decreases, the exposed area becomes insoluble in alkali and can be used as a negative resist.

  (I) The alkali-soluble structural unit (a1) having an aliphatic cyclic group having both a fluorine atom or a fluorinated alkyl group and (ii) an alcoholic hydroxyl group has both (i) and (ii). What is necessary is just to have the organic group couple | bonded with the aliphatic cyclic group and to have this cyclic group in a structural unit.

  Examples of the aliphatic cyclic group include groups in which one or more hydrogen atoms have been removed from a monocyclic or polycyclic hydrocarbon such as cyclopentane, cyclohexane, bicycloalkane, tricycloalkane, and tetracycloalkane. it can.

  More specifically, examples of the polycyclic hydrocarbon include groups in which one or more hydrogen atoms have been removed from a polycycloalkane such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclododecane. Of these, groups derived from cyclopentane, cyclohexane and norbornane by removing a hydrogen atom are preferred industrially.

  (I) Examples of the fluorine atom or fluorinated alkyl group include those in which part or all of the hydrogen atoms of the fluorine atom or lower alkyl group are substituted with fluorine atoms. Specific examples include a trifluoromethyl group, a pentafluoroethyl group, a heptafluoropropyl group, and a nonafluorobutyl group, and industrially preferred are a fluorine atom and a trifluoromethyl group.

  (Ii) The alcoholic hydroxyl group may be simply a hydroxyl group, an alcoholic hydroxyl group-containing alkyloxy group such as an alkyloxy group having a hydroxy group, an alkyloxyalkyl group or an alkyl group, or an alcoholic hydroxyl group-containing alkyl. Examples thereof include an oxyalkyl group or an alcoholic hydroxyl group-containing alkyl group. Examples of the alkyloxy group, the alkyloxyalkyl group or the alkyl group include a lower alkyloxy group, a lower alkyloxy lower alkyl group and a lower alkyl group.

  Specific examples of the lower alkyloxy group include a methyloxy group, an ethyloxy group, a propyloxy group, and a butyloxy group. Specific examples of the lower alkyloxy and lower alkyl group include a methyloxymethyl group, an ethyl group, and the like. An oxymethyl group, a propyloxymethyl group, a butyloxymethyl group, etc. are mentioned, As a lower alkyl group, a methyl group, an ethyl group, a propyl group, a butyl group etc. are mentioned specifically ,.

  In addition, in the (ii) alcoholic hydroxyl group-containing alkyloxy group, alcoholic hydroxyl group-containing alkyloxyalkyl group, or alcoholic hydroxyl group-containing alkyl group, the alkyloxy group, the alkyloxyalkyl group, or one of hydrogen atoms of the alkyl group. A part or all of them may be substituted with a fluorine atom. Preferably, in the alcoholic hydroxyl group-containing alkyloxy group or the alcoholic hydroxyl group-containing alkyloxyalkyl group, a part of the hydrogen atoms in the alkyloxy part thereof is substituted with a fluorine atom, in the alcoholic hydroxyl group-containing alkyl group, Examples thereof include those in which part of the hydrogen atoms of the alkyl group is substituted with fluorine atoms, that is, alcoholic hydroxyl group-containing fluoroalkyloxy groups, alcoholic hydroxyl group-containing fluoroalkyloxyalkyl groups, or alcoholic hydroxyl group-containing fluoroalkyl groups.

Examples of the alcoholic hydroxyl group-containing fluoroalkyloxy group include (HO) C (CF ₃ ) ₂ CH ₂ O— group, 2-bis (trifluoromethyl) -2-hydroxy-ethyloxy group, (HO) C (CF ₃ ). ₂ CH ₂ CH ₂ O— group, 3-bis (trifluoromethyl) -3-hydroxy-propyloxy group and the like. Examples of the alcoholic hydroxyl group-containing fluoroalkyloxyalkyl group include (HO) C (CF ₃ ). ₂ CH ₂ O—CH ₂ — group, (HO) C (CF ₃ ) ₂ CH ₂ CH ₂ O—CH ₂ — group, and the like. Examples of the alcoholic hydroxyl group-containing fluoroalkyl group include (HO) C (CF _{3) 2} CH ₂ - group, 2- bis (trifluoromethyl) -2-hydroxy - _{ethyl, (HO) C (CF 3} ) 2 CH 2 CH 2 - group, 3-bis (trifluoromethyl) -3 - Proxy - propyl group and the like.

  These groups (i) and (ii) may be bonded directly to the aliphatic cyclic group. In particular, (a1) the structural unit is an alcoholic hydroxyl group-containing fluoroalkyloxy group, an alcoholic hydroxyl group-containing fluoroalkyloxyalkyl group or an alcoholic hydroxyl group-containing fluoroalkyl group bonded to a norbornene ring, and the double bond of the norbornene ring is A unit represented by the following general formula (1) formed by cleavage is preferable because it is excellent in transparency, alkali solubility and dry etching resistance, and is easily available industrially.

In General Formula (1), Z is an oxygen atom, an oxymethylene group (—O (CH ₂ ) —), or a single bond, and n ′ and m ′ are each independently an integer of 1 to 5. .

  And the polymer unit used in combination with such (a1) unit can use a conventionally well-known thing, and is not specifically limited. When used as a polymer component (A-1) whose alkali solubility is increased by the action of a positive acid, the structural unit (a2) derived from a (meth) acrylic ester having a known acid dissociable, dissolution inhibiting group is dissolved. This is preferable because of excellent image properties.

  Examples of the structural unit (a2) include structural units derived from tertiary alkyl esters of (meth) acrylic acid such as tert-butyl (meth) acrylate and tert-amyl (meth) acrylate.

  The polymer component (A) of the present invention further comprises a fluorinated alkylene structural unit (a3) that improves the transparency of the polymer, and the polymer (A-2) that increases alkali solubility by the action of an acid. ). By including such a structural unit (a3), the transparency is further improved. The structural unit (a3) is preferably a unit derived from tetrafluoroethylene.

  The general formulas (2) and (3) representing the polymer component (A-1) and the polymer component (A-2) are shown below.

In the general formula (2), Z, n ′, and m ′ are the same as those in the general formula (1), R ₁ is a hydrogen atom or a methyl group, and R ₂ is an acid dissociable, dissolution inhibiting group. .

In the general formula (3), Z, n ′, m ′, R ₁ and R ₂ are the same as those in the general formula (2).

  The polymer (A-1) and the polymer (A-2) containing the general formula (1) have different structural formulas, but (i) a fluorine atom or a fluorinated alkyl group and (ii) an alcohol. Having an aliphatic-soluble structural unit (a1) having an aliphatic cyclic group having both a functional hydroxyl group and having the following structural units included in the concept of a polymer whose alkali-solubility changes by the action of an acid It may be a thing.

  That is, in the structural unit (a1), (i) a fluorine atom or fluorinated alkyl group and (ii) an alcoholic hydroxyl group are bonded to each other on an aliphatic cyclic group, and the cyclic group constitutes the main chain. Is.

  Examples of the (i) fluorine atom or fluorinated alkyl group include the same ones as described above. In addition, (ii) the alcoholic hydroxyl group is simply a hydroxyl group.

The polymer component (A) having such a unit is formed by cyclopolymerization of a diene compound having a hydroxyl group and a fluorine atom. As the diene compound, heptadiene that easily forms a polymer having a 5-membered ring or a 6-membered ring excellent in transparency and dry etching resistance is preferable. Further, 1,1,2,3,3-pentafluoro- A polymer component formed by cyclopolymerization of 4-trifluoromethyl-4-hydroxy-1,6-heptadiene (CF ₂ ═CFCF ₂ C (CF ₃ ) (OH) CH ₂ CH═CH ₂ ) is industrially used. Most preferred.

  When used as a positive polymer component (A-3) whose alkali solubility is increased by the action of an acid, it contains a structural unit (a4) in which the hydrogen atom of the alcoholic hydroxyl group is substituted with an acid dissociable, dissolution inhibiting group. The polymer component is preferred. As the acid dissociable, dissolution inhibiting group, a chain, branched or cyclic alkyloxymethyl group having 1 to 15 carbon atoms is preferable from the dissociation property of an acid, and particularly a lower alkoxymethyl group such as a methoxymethyl group. It is excellent in resolution and pattern shape. The acid dissociable, dissolution inhibiting group is preferably in the range of 10 to 40%, preferably 15 to 30%, with respect to the total hydroxyl groups, and is excellent in pattern forming ability.

  The general formula (4) representing the polymer component (A-3) is shown below.

In the general formula (4), R ₃ is a hydrogen atom or a C1-C15 alkyloxymethyl group, and a methoxymethyl group is particularly preferable. x and y are each in the range of 10 to 50 mol%. In addition, resins having different protection rates of hydrogen atoms of alcoholic hydroxyl groups may be mixed and used.

  Such a polymer component (A) can be synthesized by a known method. Moreover, the polystyrene conversion mass average molecular weight by GPC of resin of this (A) component is although it does not specifically limit, It is 5000-80000, More preferably, it is 8000-50000.

  Moreover, (A) component can be comprised from 1 type, or 2 or more types of resin, for example, some selected from the above-mentioned (A-1), (A-2), and (A-3) Two or more of these may be mixed and used, and other known resins for photoresist compositions may also be mixed and used.

  The acid generator component (B) in the photoresist composition of the present invention comprises (B-1) an onium salt having a linear fluoroalkylsulfonic acid ion as an anion part, and (B-2) not fluorine-substituted. And at least an onium salt having a sulfonate ion having a heterocyclic ring as an anion portion.

  Examples of the component (B-1) include diphenyliodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, bis (4-tert-butylphenyl) iodonium trifluoromethanesulfonate or nonafluorobutanesulfonate, and triphenylsulfonium trifluoromethanesulfonate. , Its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, tri (4-methylphenyl) sulfonium trifluoromethanesulfonate, its heptafluoropropane sulfonate or its nonafluorobutane sulfonate, dimethyl (4-hydroxynaphthyl) sulfonium trifluoromethanesulfonate , Its heptafluoropropane sulfonate or its nona Carbon numbers such as trifluorobutane sulfonate, monophenyldimethylsulfonium trifluoromethane sulfonate, heptafluoropropane sulfonate or nonafluorobutane sulfonate, diphenyl monomethylsulfonium trifluoromethane sulfonate, heptafluoropropane sulfonate or nonafluorobutane sulfonate Examples thereof include onium salts having 1 to 10 linear fluoroalkylsulfonate ions as an anion moiety.

  The number of carbon atoms of the linear fluoroalkylsulfonic acid ion in the above (B-1) is in the range of 1 to 10, preferably in the range of 1 to 6, more preferably in the range of 1 to 4, most preferably It has 4 carbon atoms.

  On the other hand, the number of carbon atoms of the heterocyclic ring not substituted with fluorine in (B-2) is preferably in the range of 5-10. Specifically, it is preferably an onium salt having camphorsulfonic acid (also referred to as camphorsulfonic acid) as the anion moiety, and particularly preferably an onium salt having the following compound (5) as the anion moiety.

  By combining (B-1) and (B-2), the rectangularity and LER of the resist pattern can be improved. A preferable mixing ratio is such that the ratio of (B-2) is 5 to 60% by mass, preferably 10 to 30% by mass, based on the entire component (B). If it is less than 5% by mass, good effects are not recognized, and if it exceeds 60% by mass, it is not desirable from the viewpoint of transparency.

  The cation part (cationic site) of the acid generators (B-1) and (B-2) is preferably an iodonium salt or a sulfonium salt. More preferably, it is a sulfonium salt. Among these, what the cation part of the said acid generator is a compound represented by following General formula (6) is desirable.

In General Formula (6), R _{4 to} R ₆ each independently represents an aryl group or an alkyl group. At least one of R _{4 to} R ₆ represents an aryl group. Of R _{4 to} R ₆ , two or more are preferably aryl groups, and most preferably R _{4 to} R ₆ are all aryl groups.

The aryl group of R ₄ to R _6, is not particularly limited, for example, an aryl group having 6 to 20 carbon atoms, an alkyl group, a phenyl group which may not be substituted with a halogen atom or the like And a naphthyl group. An aryl group having 6 to 10 carbon atoms is preferable because it can be synthesized at low cost.

There is no restriction | limiting in particular as an alkyl group of R < ₄ > -R < ₆ >, For example, a C1-C10 linear, branched or cyclic alkyl group etc. are mentioned. It is preferable that it is C1-C5 from the point which is excellent in resolution. Specific examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an n-pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a nonyl group, and a decanyl group. A methyl group is preferable because it is excellent in resolution and can be synthesized at low cost. Among these, it is most preferable that all of R _{4 to} R ₆ are phenyl groups.

The component (B) may further contain an acid generator component other than the components (B-1) and (B-2). Specifically, for example, bis (isopropylsulfonyl) diazomethane, bis (p-toluenesulfonyl) diazomethane, bis (1,1-dimethylethylsulfonyl) diazomethane, bis (cyclohexylsulfonyl) diazomethane, bis (2,4-dimethylphenyl) sulfonyl) and diazomethane-based acid generators such as diazomethane. examples of the oxime sulfonate compound, alpha-(methylsulfonyloxyimino) - phenylacetonitrile, alpha-(methylsulfonyloxyimino)-p-methoxyphenyl acetonitrile, alpha-( Trifluoromethylsulfonyloxyimino) -phenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (ethylsulfonyloxyimino) -p-meth Examples include oxime sulfonate acid generators such as xylphenylacetonitrile, α- (propylsulfonyloxyimino) -p-methylphenylacetonitrile, α- (methylsulfonyloxyimino) -p-bromophenylacetonitrile.

  (B) The compounding quantity of a component is 0.5-30 mass parts with respect to 100 mass parts of (A) component, for example, Preferably it is 1-10 mass parts. When the content is less than this range, latent image formation is insufficient, and when the content is greater, the storage stability as a resist composition may be impaired.

  The photoresist composition of the present invention can further contain (C) a dissolution inhibitor having fluorine atoms.

  Examples of the (C) fluorine-containing dissolution inhibitor used in the present invention include compounds in which at least one fluorine atom is bonded and the solubility in an alkali developer is increased by the action of an acid. . Such a compound is preferably a low molecular weight phenol, alcohol or carboxylic acid compound having a molecular weight of 100 or more and 500 or less, wherein a part of the hydrogen atom of the hydroxyl group is unstable to acid and has an ability to inhibit dissolution in alkali. A compound substituted with a group (acid dissociable, dissolution inhibiting group) can be mentioned.

  Examples of such an acid dissociable substituent include a tertiary alkyl group, a tertiary alkoxycarbonyl group, a tertiary alkoxycarbonylalkyl group, a chain or cyclic alkoxyalkyl group, and the like.

  Specifically, a tertiary alkyl group such as a tert-butyl group, a tertiary alkoxycarbonyl group such as a tert-butoxycarbonyl group, a tert-butoxycarbonylmethyl group, a tertiary alkoxycarbonylalkyl group, a methoxymethyl group, Examples thereof include a chain, branched or cyclic alkyloxymethyl group having 1 to 15 carbon atoms such as a tert-amyloxymethyl group and a 4-tertbutyl-cyclohexyloxymethyl group.

  Examples of such compounds include compounds represented by the following general formulas (7) and (8).

In general formulas (7) and (8), R ₇ is a hydrogen atom, an alkyl group, an alkoxyl group, or a fluorine atom, and R ₈ is an acid dissociable, dissolution inhibiting group. A is _{-C (C n F 2n + 1} ) -, - (C m F 2m + 1) -O-CO-O -, - (C m F 2m + 1) -O-, or -O-CO- O-, and n, m, p and q are each independently an integer of 1 to 4. However, when A is —O—CO—O—, R ₇ is a fluorine atom.

  Specific examples of the compounds represented by these general formulas include compounds represented by the following chemical formulas (9) to (14).

  Other specific compounds include 3,3 ′, 5,5′-tetrafluoro [(1,1′-biphenyl) -4,4′-di-t-butoxycarbonyl], 4,4 ′. -[2,2,2-trifluoro-1- (trifluoromethyl) ethylidene] bisphenol-4,4'-di-t-butoxycarbonyl, 2-trifluoromethylbenzenecarboxylic acid 1,1-t-butyl ester , 2-trifluoromethylcyclohexanecarboxylic acid-t-butyl ester, and a compound represented by the following chemical formula (15).

Among these, the compounds represented by the chemical formulas (9) to (15) are preferable because they have high transparency to the F ₂ excimer laser and are excellent in a fine pattern shape.

The acid dissociable, dissolution inhibiting group R ₈ is preferably a chain, branched or cyclic alkyloxymethyl group or tertiary alkyl group having 1 to 15 carbon atoms. Among these, the compounds represented by the chemical formulas (13) to (15) are preferable, and the compound represented by the chemical formula (15) is most preferable.

  The addition amount of the (C) fluorine-containing dissolution inhibitor in the photoresist composition according to the present invention is 2 to 30% by mass, preferably 3 to 10% by mass, relative to 100% by mass of the main component polymer (A) component. Is appropriate. If the addition amount of the dissolution inhibitor is less than 2% by mass, the dissolution suppression effect does not appear. On the other hand, when the addition amount exceeds 30% by mass, the heat resistance of the resist is lowered.

  When the dissolution inhibitor used in the present invention contains a fluorine atom, the transparency to 157 nm wavelength light is significantly improved. The present inventors compared (C) the case of using a dissolution inhibitor having a fluorine atom with the case of using a dissolution inhibitor having no fluorine atom. When it is used, it has been confirmed that the pattern resolution is remarkably improved.

  In the photoresist composition of the present invention, a nitrogen-containing organic compound (D) (hereinafter, referred to as “component (D)”) is further blended as an optional component in order to improve the resist pattern shape, stability with time, etc. be able to.

  Since a wide variety of components (D) have already been proposed, any known one may be used, but amines, particularly secondary aliphatic amines and tertiary aliphatic amines are preferred. Here, the aliphatic amine refers to an alkyl or alkyl alcohol amine having 15 or less carbon atoms, and examples of the secondary and tertiary amines include trimethylamine, diethylamine, triethylamine, di-n-propylamine, -N-propylamine, tripentylamine, trihexylamine, triheptylamine, trioctylamine, tridecanylamine, tridodecylamine, tritetradecanylamine, diethanolamine, triethanolamine, triisopropanolamine, etc. In particular, tertiary alkanolamines such as triethanolamine and triisopropanol are preferred. These may be used alone or in combination of two or more. (D) component is normally used in 0.01-5.0 mass parts with respect to 100 mass parts of (A) component.

  In addition, for the purpose of preventing sensitivity deterioration due to the blending with the component (D) and improving the resist pattern shape, retention stability and the like, as an optional component, (E) an organic carboxylic acid or an oxo acid of phosphorus or A derivative thereof (hereinafter referred to as component (E)) can be contained. In addition, (D) component and (E) component can also be used together, and any 1 type can also be used.

  As the organic carboxylic acid, for example, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid and the like are suitable.

  Phosphorus oxoacids or derivatives thereof include phosphoric acid, phosphoric acid di-n-butyl ester, phosphoric acid diphenyl ester and other phosphoric acid or derivatives thereof such as phosphonic acid, phosphonic acid dimethyl ester, phosphonic acid- Like phosphonic acids such as di-n-butyl ester, phenylphosphonic acid, phosphonic acid diphenyl ester, phosphonic acid dibenzyl ester and their esters, phosphinic acids such as phosphinic acid, phenylphosphinic acid and their esters Of these, salicylic acid and phenylphosphonic acid are particularly preferred. (E) A component is used in the ratio of 0.01-5.0 mass parts per 100 mass parts of (A) component.

  The photoresist composition of the present invention is used as a uniform solution by dissolving the component (A), the component (B), and the components (C) to (E) as appropriate in an organic solvent. Specific examples of such organic solvents include ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, and 2-heptanone; ethylene glycol, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monoacetate, propylene glycol, Polyhydric alcohols such as propylene glycol monoacetate, dipropylene glycol, or dipropylene glycol monoacetate, such as monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether, or monophenyl ether; and cyclic ethers such as dioxane Class: methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methoxy Methyl propionate, esters such as ethyl ethoxypropionate can be exemplified. These organic solvents may be used independently and may be used as 2 or more types of mixed solvents. Of these, propylene glycol monomethyl ether acetate (PGMEA), ethyl lactate (EL) and the like are preferable. The amount of the organic solvent is a concentration that can be applied to a substrate or the like when forming a resist film.

  In addition, the photoresist composition of the present invention further contains miscible additives as desired, for example, an additional resin for improving the performance of the resist film, a surfactant for improving the coating property, a dissolution inhibitor, Plasticizers, stabilizers, colorants, antihalation agents and the like can be added and contained.

The method for forming a resist pattern of the present invention is to form a resist pattern by an ordinary lithography process using the above-described photoresist composition. In such a method, first, a photoresist composition is applied on a substrate by spin coating or the like and dried to form a resist film. Subsequently, it selectively exposes through a mask pattern and heats after exposure. Finally, development is performed with an alkaline aqueous solution to form a resist pattern. In addition, you may perform a post-baking process as needed. The light source is not limited, but far ultraviolet light of 200 nm or less, specifically ArF excimer laser, F ₂ excimer laser, EUV (extreme ultraviolet light), electron beam, soft X-ray, X-ray, etc. Can be used. In particular, an F ₂ excimer laser is preferable.

As the substrate, an organic or inorganic antireflection film or a substrate provided with various thin films such as SiON, silicon nitride (SiN), and trisilicon tetranitride (Si ₃ N ₄ ) is used.

  Hereinafter, the present invention will be described in more detail based on examples. In addition, this invention is not limited to the following Example.

<Example 1>
As component (A), a fluorine-containing polymer (in the general formula (4), 20% of R ₃ is protected with a methoxymethyl group and the remaining 80% is a hydrogen atom. X: Y = 50: 50 (molar ratio) 100 parts by weight, 4.0 parts by weight of triphenylsulfonium nonafluorobutanesulfonate as component (B-1), and 1.0 parts by weight of the following chemical formula (16) as component (B-2) And 0.1 part by mass of triisopropanolamine, 0.1 part by mass of salicylic acid, and 5 parts by mass of a fluorine-containing dissolution inhibitor represented by the chemical formula (15), 1300 parts by mass of propylene glycol monomethyl ether acetate (PGMEA) Were added to and mixed with each other to obtain a photoresist composition.

  As a substrate for forming a resist film, an 8-inch silicone wafer on which a SiON thin film was formed was used. On the substrate, the above-described photoresist composition was uniformly applied by spin coating, heated at 90 ° C. for 90 seconds, and dried to obtain a resist film having a thickness of 180 nm.

The resist film was selectively exposed through a mask with an F ₂ excimer laser (wavelength 157 nm) using an F ₂ exposure apparatus (NA = 0.85, 1/2 ring manufactured by Exitech).

  After the exposure, the film was heated at 120 ° C. for 90 seconds, and the pattern was developed with a 2.38 wt% solution of tetramethylammonium hydroxide. The development temperature was 23 ° C. and the development time was 60 seconds. After development, it was washed with deionized water and dried.

As a result, a 200 nm pitch line and space (1: 1.5) pattern was formed on the substrate (the line portion was 80 nm and the space portion was 120 nm). The sensitivity at this time was 71 mJ / cm ² . When the cross-sectional shape of the line of this pattern was observed, it showed a clear rectangle. Moreover, when the unevenness | corrugation of the side wall between resist patterns was observed with SEM (scanning electron microscope), the roughness was hardly recognized.

<Comparative Example 1>
In the same manner as in Example 1 except that (B-2) component was not used as the acid generator and 5.0 parts by mass of triphenylsulfonium nonafluorobutanesulfonate was used as the (B-1) component, Attempted formation.

As a result, a 200 nm pitch line and space (1: 1.5) pattern was formed on the substrate (the line portion was 80 nm and the space portion was 120 nm). The sensitivity at this time was 12.0 mJ / cm ² . When the cross-sectional shape of the line of this pattern was observed, the top of the resist pattern was rounded. Further, when the unevenness of the sidewalls between the resist patterns was observed by SEM (scanning electron microscope), a lot of roughness was recognized as compared with Example 1.

As described above, the photoresist composition and the resist pattern forming method according to the present invention are useful for patterning of semiconductor integrated circuits by lithography, and in particular, ArF excimer laser light and F ₂ excimer laser light that are exposure light of 200 nm or less. It is suitable for fine patterning using the like.

Claims (11)

(A) (i) a polymer comprising an alkali-soluble constituent unit having an aliphatic cyclic group having both a fluorine atom or a fluorinated alkyl group and (ii) an alcoholic hydroxyl group, wherein the alkali solubility is changed by the action of an acid Ingredients,
(B) an acid generator component that generates acid upon exposure to light,
(B-1) at least an onium salt having a linear fluoroalkyl sulfonate ion as an anion part, and (B-2) an onium salt having a sulfonate ion having a heterocyclic ring not substituted with fluorine as an anion part. An acid generator component comprising,
A photoresist composition comprising:   2. The photoresist composition according to claim 1, wherein the carbon number of the linear fluoroalkylsulfonic acid ion in (B-1) is in the range of 1 to 10. 3.   3. The photoresist composition according to claim 1, wherein a ratio of (B-2) in the component (B) is 5 to 60 mass% with respect to the total amount of the component (B).   The photoresist composition according to any one of claims 1 to 3, wherein the number of carbon atoms of the heterocyclic ring not substituted with fluorine in (B-2) is in the range of 5 to 10.   5. The photoresist composition according to claim 1, wherein the sulfonate ion in (B-2) is a camphorsulfonate ion. 6.   6. The photoresist composition according to claim 1, further comprising (C) a dissolution inhibitor having a fluorine atom.   Furthermore, (D) The photoresist composition of any one of Claims 1-6 containing a nitrogen-containing organic compound.   The photoresist composition according to any one of claims 1 to 7, further comprising (E) an organic carboxylic acid or an oxo acid of phosphorus or a derivative thereof.   The photoresist composition according to any one of claims 1 to 8 is applied onto a substrate to form a resist film, the resist film is selectively exposed, and then subjected to heating and development. A resist pattern forming method, comprising forming a resist pattern on a substrate. The resist pattern forming method according to claim 9, wherein the exposure light source is F ₂ excimer laser light. 11. The resist pattern forming method according to claim 9, wherein the substrate is a substrate provided with a SiON film.