KR100881304B1 - Positive resist composition and method for forming resist pattern - Google Patents

Abstract

This positive resist composition contains the resin component (A) which alkali solubility increases by the action of an acid, and the acid generator component (B) which generate | occur | produces an acid by exposure, (A) component from hydroxystyrene A hydroxyl group of the first structural unit derived, the second structural unit derived from the (meth) acrylic acid ester having an alcoholic hydroxyl group, the structural unit derived from hydroxystyrene, and the third structural unit protected with an acid dissociable, dissolution inhibiting group and / or A first resin component having a fourth structural unit in which an alcoholic hydroxyl group of a structural unit derived from a (meth) acrylic acid ester having an alcoholic hydroxyl group is protected with an acid dissociable, dissolution inhibiting group, a fifth structural unit derived from hydroxystyrene, The hydroxyl group of the structural unit derived from hydroxystyrene is a sixth structural unit protected by an acid dissociable, dissolution inhibiting group. It is a positive resist composition containing the second resin component (A2).

Description

Positive resist composition and resist pattern formation method {POSITIVE RESIST COMPOSITION AND METHOD FOR FORMING RESIST PATTERN}

The present invention relates to a positive resist composition and a resist pattern forming method using the same.

This application claims priority based on Japanese Patent Application No. 2005-060518 for which it applied on March 4, 2005, and uses the content here.

As a resist material that satisfies the conditions of high resolution capable of reproducing fine-dimensional patterns, a base resin in which alkali solubility is changed by the action of an acid, and a chemical in which an acid generator which generates an acid by exposure is dissolved in an organic solvent. Amplified resist compositions are known.

The chemically amplified positive resist composition proposed as a resist material suitable for a method of exposing with a KrF excimer laser is generally one in which a part of the hydroxyl group of a polyhydroxystyrene resin as a base resin is protected by an acid dissociable, dissolution inhibiting agent. It is used (for example, refer patent document 1).

As the acid dissociable, dissolution inhibiting group, a third group represented by a so-called acetal group and tert-butyl group such as a cyclic ether group represented by a chain ether group represented by 1-ethoxyethyl group or a tetrahydropyranyl group Tertiary alkoxycarbonyl groups represented by tertiary alkyl groups and tert-butoxycarbonyl groups are mainly used.

Patent document 1: Unexamined-Japanese-Patent No. 4-211258

Disclosure of the Invention

Problems to be Solved by the Invention

In recent years, as the speed of miniaturization is gradually accelerated, further resolution is required for the resist material. However, it cannot be said that the positive resist composition using the conventional polyhydroxy styrene resin as mentioned above has sufficient resolution and resist pattern shape.

This invention is made | formed in view of the said situation, and an object of this invention is to provide the positive resist composition excellent in the resolution and the shape of a resist pattern.

Means to solve the problem

In order to achieve the above object, the present invention adopts the following configuration.

1st aspect of this invention is a positive resist composition containing the resin component (A) which alkali solubility increases by the action of an acid, and the acid generator component (B) which generate | occur | produces an acid by exposure, The said resin component (A) The hydroxyl group of the 1st structural unit (a1) derived from this hydroxy styrene, the 2nd structural unit (a2) derived from the (meth) acrylic acid ester which has an alcoholic hydroxyl group, and the structural unit derived from hydroxy styrene. A fourth structural unit in which the alcoholic hydroxyl group of the structural unit derived from the (meth) acrylic acid ester having a third structural unit (a3) and / or an alcoholic hydroxyl group protected with an acid dissociable, dissolution inhibiting group is protected with an acid dissociable, dissolution inhibiting group ( The first resin component (A1) having a4), the fifth structural unit (a5) derived from hydroxystyrene, and the structural unit derived from hydroxystyrene The hydroxyl group of contains a 2nd resin component (A2) which has the 6th structural unit (a6) protected by the acid dissociable, dissolution inhibiting group, It is a positive resist composition characterized by the above-mentioned.

In addition, a second aspect of the present invention provides a resist comprising forming a resist film on a substrate using the positive resist composition of the first aspect, exposing the resist film, and developing the resist film to form a resist pattern. Pattern formation method.

In addition, in this specification, "(meth) acrylic acid" means one or both of methacrylic acid and acrylic acid. A "structural unit" means the monomeric unit which comprises a polymer.

Effects of the Invention

According to the present invention, a positive resist composition having excellent resolution and shape of a resist pattern can be obtained.

Implement the invention  Best form for

The positive resist composition of the present invention has an acid dissociable, dissolution inhibiting group, a resin component (A) (hereinafter sometimes referred to as component (A)) in which alkali solubility increases by the action of an acid, and an acid by exposure. And an acid generator component (B) (hereinafter, sometimes referred to as component (B)) for generating a solvent.

In the component (A), when the acid generated from the component (B) acts upon exposure, the acid dissociable, dissolution inhibiting group is dissociated, whereby the entire component (A) changes from alkali insoluble to alkali soluble.

Therefore, in forming a resist pattern, when exposed through a mask pattern or heating after exposure in addition to the exposure, the exposed portion is converted to alkali solubility while the unexposed portion does not change while being insoluble in alkali. A positive resist pattern can be formed.

<Resin Component (A)>

In the present invention, the resin component (A) (hereinafter sometimes referred to as component (A)) contains the first resin component (A1) and the second resin component (A2).

<1st resin component (A1)>

The first resin component (A1) (hereinafter also referred to as component (A1)) has the following structural unit (a1), structural unit (a2), structural unit (a3) and / or (a4).

(a1): 1st structural unit derived from hydroxy styrene (Hereinafter, it may be called unit (a1).)

(a2): 2nd structural unit derived from the (meth) acrylic acid ester which has an alcoholic hydroxyl group (Hereinafter, it may be called a (a2) unit.)

(a3): 3rd structural unit in which the hydroxyl group of the structural unit derived from hydroxy styrene was protected by the acid dissociable, dissolution inhibiting group (Hereinafter, it may be called (a3) unit.)

(a4): 4th structural unit in which the alcoholic hydroxyl group of the structural unit derived from the (meth) acrylic acid ester which has an alcoholic hydroxyl group was protected by the acid dissociable, dissolution inhibiting group (Hereinafter, it may be called (a4) unit.)

In addition to these units (a1) to (a4), the component (A1) may further have a seventh structural unit (a7) (hereinafter, sometimes referred to as (a7) unit) derived from styrene.

[First structural unit (a1)]

The unit (a1) is a structural unit derived from hydroxystyrene and is represented by the following general formula (I). That is, hydroxy styrene here means literally one or both of hydroxy styrene or (alpha) -methylhydroxy styrene.

(In formula, R is a hydrogen atom or a methyl group, m shows the integer of 1-3.)

In general formula (I), R is a hydrogen atom or a methyl group, and it is preferable that it is a hydrogen atom. m is preferably 1. The position of the hydroxyl group may be any of the o-position, the m-position, and the p-position, but the p-position is preferable because it is readily available and inexpensive.

It is preferable that it is 20-80 mol% with respect to all the structural units which comprise (A1) component, and, as for the ratio of a structural unit (a1) in (A1) component, it is more preferable that it is 30-70 mol%, 40- It is especially preferable that it is 70 mol%, and it is most preferable that it is 45-65 mol%. Thereby, moderate alkali solubility can be obtained.

[Second structural unit (a2)]

The unit (a2) is a structural unit derived from (meth) acrylic acid ester having an alcoholic hydroxyl group.

The 1st resin component (A1) has such a structural unit (a2), and is alkalin than resin (henceforth PHS resin) which protects a part of hydroxyl groups of polyhydroxystyrene with an acid dissociable, dissolution inhibiting group. Solubility in a developing solution is low.

That is, in PHS resin, all except the unit protected by the acid dissociable, dissolution inhibiting group are structural units derived from hydroxy styrene (hydroxy styrene unit), and the hydroxyl group of the hydroxy styrene unit is a phenolic hydroxyl group. On the other hand, in addition to the hydroxystyrene unit (a1), the first resin component (A1) has a structural unit (a2) having an alcoholic hydroxyl group inferior in alkali solubility to the phenolic hydroxyl group. Therefore, the solubility of the copolymer (A1) in the alkaline developing solution can be made smaller than that of the PHS resin. Thereby, it can contribute to reducing defects and improving resolution by lowering a protection rate.

The structural unit (a2) should just be a structural unit derived from the (meth) acrylic acid ester which has an alcoholic hydroxyl group which has such an effect, Although it does not specifically limit, It has an alcoholic hydroxyl group from the point which is excellent in high resolution and dry etching resistance. The structural unit guide | induced from an aliphatic polycyclic group containing (meth) acrylic acid ester is mentioned as a preferable thing.

As a polycyclic group which comprises the aliphatic polycyclic group which has the said alcoholic hydroxyl group, the group etc. which removed one hydrogen atom from bisylchloroalkane, tricycloalkane, tetracycloalkane, etc. can be illustrated. Specifically, the group remove | excluding one hydrogen atom from polycycloalkane, such as adamantane, norbornane, isobornane, tricyclodecane, and tetracyclo dodecane, etc. are mentioned. Such polycyclic groups can be appropriately selected and used among a large number of proposed ones in ArF resists. Among these, adamantyl group, norbornyl group, and tetracyclododecanyl group are industrially preferable.

As a structural unit (a2), the structural unit derived from the adamantyl group containing (meth) acrylic acid ester which has at least 1 alcoholic hydroxyl group especially represented by the following general formula (II) can be used preferably.

Among the structural units (a2) represented by the following general formula (II), most preferred are structural units represented by the following general formula (IIa).

(In formula, R is a hydrogen atom or a methyl group, x is an integer of 1-3.)

It is preferable that it is 5-40 mol% with respect to all the structural units which comprise (A1) component, and, as for the ratio of a structural unit (a2) in (A1) component, it is more preferable that it is 5-30 mol%, 10-10 It is especially preferable that it is 25 mol%, and it is most preferable that it is 10-20 mol%. Thereby, the resolution improves and the effect of reducing defect is acquired.

[Third structural unit (a3) and fourth structural unit (a4)]

The third structural unit (a3) is a structural unit in which the hydroxyl group of the same structural unit as the first structural unit (a1) is protected with an acid dissociable, dissolution inhibiting group. The hydroxystyrene skeleton in the 1st structural unit (a1) and 3rd structural unit (a3) which exists in (A1) component may be same or different. Preferably the same.

The fourth structural unit (a4) is a structural unit in which an alcoholic hydroxyl group of the same structural unit as the second structural unit (a2) is protected with an acid dissociable, dissolution inhibiting group. The (meth) acrylic acid ester frame | skeleton in the 2nd structural unit (a2) and 4th structural unit (a4) which exists in (A1) component may be same or different. Preferably the same.

In the component (A1), both of the unit (a3) and the unit (a4) may be contained, and only one of the units may be contained, but only the unit (a3) or the unit (a3) and the unit (a4) may be contained. It is preferable to contain both of a unit.

Acid Dissociative Dissolution Inhibitors

As an acid dissociable, dissolution inhibiting group in a 3rd structural unit (a3) and a 4th structural unit (a4), acid dissociable dissolution in the conventional chemically amplified type KrF positive type resist composition and ArF positive type resist composition. What has been proposed as an inhibitor can be used suitably. For example, chain or cyclic agents such as tert-butyl group, tert-amyl group, 1-methylcyclopentyl group, 1-ethylcyclopentyl group, 1-methylcyclohexyl group, and 1-ethylcyclohexyl group Cyclic ether groups, such as a tertiary alkyl group, tetrahydropyranyl group, and tetrahydrofuranyl group, 1-lower alkoxyalkyl group, etc. can be used. Among the 1-lower alkoxyalkyl groups, in particular, the 1-lower alkoxyalkyl group represented by the following general formula (III) is preferable. Specific examples thereof include a chain or branched alkoxyalkyl group such as 1-ethoxyethyl group and 1-isopropoxyethyl group, 1-cyclohexyloxyethyl group, 1-adamantoxymethyl group, 2-adamantoxymethyl group and 1-a Cyclic alkoxyalkyl groups, such as methoxyethyl group and 2-adamantoxyethyl group, are mentioned, Among them, 1-ethoxyethyl group is preferable at the point which is excellent in the resolution performance especially.

(In formula, R <^1> represents a hydrogen atom or a C1-C4 linear or branched alkyl group, R <^2> represents a C1-C8 chain or branched alkyl group, or a C5-C7 cycloalkyl group. )

The component (A1) is, for example, a monomer corresponding to the structural unit (a1) and a monomer corresponding to the structural unit (a2), for example, azobisisobutyronitrile (AIBN) and azobis (2-methyl Copolymerization by a conventional method such as a known radical polymerization method using a radical polymerization initiator such as propionate), and then dissociating the acid groups of the structural unit (a1) and / or the structural unit (a2) by a known method. It can be manufactured by the method of protecting by a sex-dissolution inhibiting group, and forming a structural unit (a3) and / or a structural unit (a4).

Or after preparing the monomer corresponded to a structural unit (a3) in advance, and copolymerizing this monomer and the monomer corresponded to a structural unit (a2) by a conventional method, the acid of a structural unit (a3) is hydrolyzed. A part of the dissociable, dissolution inhibiting group may be replaced with a hydroxyl group to form the structural unit (a1), and if necessary, a method of producing the structural unit (a2) may also be produced by a method of protecting the hydroxyl group of the structural unit (a2) with an acid dissociable, dissolution inhibiting group. Can be.

It is preferable that it is 5-50 mol% with respect to all the structural units which comprise (A1) component, and, as for the ratio of a structural unit (a3) in (A1) component, it is more preferable that it is 5-40 mol%, 10-30 It is especially preferable that it is mol%, and it is most preferable that it is 15-30 mol%.

It is preferable that it is 1-10 mol% with respect to all the structural units which comprise (A1) component, and, as for the ratio of a structural unit (a4) in (A1) component, it is more preferable that it is 1-8 mol%, 1-6 It is especially preferable that it is mol%, and it is most preferable that it is 1-5 mol%.

By setting it as said range, since the effect of this invention is excellent, it is preferable.

[7th structural unit (a7)]

The structural unit (a7) is a structural unit derived from styrene, and is represented by the following general formula (IV). That is, styrene here means both literal styrene and (alpha) -methylstyrene.

(Wherein R is a hydrogen atom or a methyl group)

In the first resin component (A1), the unit (a7) is not essential, but if it is contained, an advantage of improving the depth of focus and improving dry etching resistance can be obtained.

When it contains (a7) unit, it is preferable that the ratio of the (a7) unit in a 1st resin component (A1) is 0.5-10 mol% of the sum total of all the structural units which comprise a 1st resin component (A1), More preferably, it is 2-5 mol%. When there are more (a7) units than the said range, there exists a tendency for the solubility to a developing solution to deteriorate.

It is preferable that the mass mean molecular weight (polystyrene conversion by gel permeation chromatography, same as below) of a 1st resin component (A1) is 3000 or more and 20000 or less, More preferably, it is 5000 or more and 15000 or less. The rectangularity of the resist pattern obtained improves that the mass mean molecular weight is below the upper limit of the said range. In addition, it is possible to prevent the occurrence of the micro bridge. Moreover, etching resistance and heat resistance are favorable as the mass mean molecular weight is more than the lower limit of the said range.

The microbridge here is a kind of development defect, and means the defect which the part near the surface of the adjacent resist pattern connected to the resist, and became the bridge | crosslinked state in a line and space pattern, for example. Microbridges are more likely to occur as the mass average molecular weight is higher and as the temperature of post-exposure heating (PEB) is higher.

Moreover, if the dispersion degree (Mw / Mn ratio) of a 1st resin component (A1) is monodispersion with small dispersion degree, it is excellent in resolution and is preferable. Specifically, it is 1-3, Preferably it is 1-2.

<2nd resin component (A2)>

The second resin component (A2) (hereinafter sometimes referred to as component (A2)) is a hydroxyl group of the fifth structural unit (a5) derived from hydroxystyrene and the structural unit derived from hydroxystyrene. It has the 6th structural unit (a6) protected by the dissolution suppressor.

The fifth structural unit (a5) is the same as the first structural unit (a1).

It is preferable that it is 20-80 mol% with respect to all the structural units which comprise (A2) component, and, as for the ratio of a structural unit (a5) in (A2) component, it is more preferable that it is 30-80 mol%, 40-80 It is especially preferable that it is mol%, and it is most preferable that it is 50-80 mol%.

In addition, a 6th structural unit (a6) is the same as that of the said 3rd structural unit (a3). The hydroxystyrene skeleton in the 5th structural unit (a5) and 6th structural unit (a6) which exists in (A2) component may be same or different. Preferably the same.

It is preferable that it is 5-50 mol% with respect to all the structural units which comprise (A2) component, and, as for the ratio of a structural unit (a6) in (A2) component, it is more preferable that it is 10-45 mol%, 15-40 It is especially preferable that it is mol%, and it is most preferable that it is 20-40 mol%.

Although the 2nd resin component (A2) may contain structural units other than a 5th structural unit (a5) and a 6th structural unit (a6) in the range which does not impair the effect of this invention, 5th structural unit (a5) And the sixth structural unit (a6).

In addition, in this invention, it is assumed that the said 1st resin component (A1) is not contained in a 2nd resin component (A2).

The second resin component (A2) can be obtained by protecting a part of the hydroxyl groups of the polymer composed of the fifth structural unit (a5) with an acid dissociable, dissolution inhibiting group. Alternatively, the monomer corresponding to the fifth structural unit (a5) and the monomer corresponding to the sixth structural unit (a6) may be copolymerized by a known method for production.

In 2nd resin component (A2), it is preferable that the sum total of (a5) unit and (a6) unit is 50 mol% or more of the sum total of all the structural units which comprise this (A2) component, More preferably, it is 75 mol It is more than% and 100 mol% is the most preferable.

It is preferable that the mass mean molecular weights of a 2nd resin component (A2) are 3000 or more and 30000 or less, More preferably, they are 5000 or more and 25000 or less. The rectangularity of the resist pattern obtained improves that the mass mean molecular weight is below the upper limit of the said range. In addition, it is possible to prevent the occurrence of the micro bridge. Moreover, etching resistance and heat resistance are favorable as the mass mean molecular weight is more than the lower limit of the said range.

Moreover, if the dispersion degree (Mw / Mn ratio) of 2nd resin component (A2) is monodispersion with a small dispersion degree, it is excellent in resolution and is preferable. Specifically, it is 1-3, Preferably it is 1-2.

In component (A), the mass ratio (A1) :( A2) of the first resin component (A1) and the second resin component (A2) is preferably from 9: 1 to 1: 9, and from 9: 1 to 2: 8 More preferably, 9: 1-4: 6 are especially preferable, and 9: 1-7: 3 are the most preferable. By setting it as said range, the effect of this invention is excellent. Further, the separator margin, LER (line edge roughness), and resist pattern shape are also good.

Moreover, in addition to the said 1st resin component (A1) and a 2nd resin component (A2), (A) component mix | blends other resin which can be used for positive resist compositions, such as polyhydroxy styrene resin and (meth) acrylic resin, suitably Although it may be sufficient, it is preferable that the sum total of a 1st resin component (A1) and a 2nd resin component (A2) is 80 mass% or more in (A) component contained in a positive resist composition for the effect of this invention, and it is 90 mass More than% is more preferable, Most preferably, it is 100 mass%.

<Acid generator component (B)>

The component (B) can be used without particular limitation from known acid generators used in conventional chemically amplified resist compositions.

Examples of such acid generators include onium salt acid generators such as iodonium salts and sulfonium salts, oxime sulfonate acid generators, bisalkyl or bisarylsulfonyldiazomethanes, and poly (bissulfonyl) diazos Many kinds of diazomethane-based acid generators such as methane, nitrobenzylsulfonate-based acid generators, iminosulfonate-based acid generators and disulfone-based acid generators are known.

Specific examples of onium salt-based acid generators include trifluoromethanesulfonate or nonafluorobutanesulfonate of diphenyliodonium, trifluoromethanesulfonate or nonafluoro of bis (4-tert-butylphenyl) iodonium Butanesulfonate, trifluoromethanesulfonate of triphenylsulfonium, heptafluoropropanesulfonate or nonafluorobutanesulfonate thereof, trifluoromethanesulfonate of tri (4-methylphenyl) sulfonium, hepta Fluoropropanesulfonate or nonafluorobutanesulfonate thereof, trifluoromethanesulfonate of dimethyl (4-hydroxynaphthyl) sulfonium, heptafluoropropanesulfonate or nonafluorobutanesulfonate thereof, mono Trifluoromethanesulfonate of phenyldimethylsulfonium, heptafluoropropanesulfonate or nonafluorobutanesulfonate thereof, di Trifluoromethanesulfonate of nilmonomethylsulfonium, heptafluoropropanesulfonate or nonafluorobutanesulfonate thereof, trifluoromethanesulfonate of (4-methylphenyl) diphenylsulfonium, heptafluoro Propanesulfonate or nonafluorobutanesulfonate thereof, trifluoromethanesulfonate of (4-methoxyphenyl) diphenylsulfonium, heptafluoropropanesulfonate or nonafluorobutanesulfonate thereof, tri (4 trifluoromethanesulfonate of -tert-butyl) phenylsulfonium, its heptafluoropropanesulfonate or its nonafluorobutanesulfonate, and the like.

Specific examples of the oxime sulfonate-based acid generator include α- (p-toluenesulfonyloxyimino) -benzyl cyanide, α- (p-chlorobenzenesulfonyloxyimino) -benzyl cyanide, and α- (4- Nitrobenzenesulfonyloxyimino) -benzylcyanide, α- (4-nitro-2-trifluoromethylbenzenesulfonyloxyimino) -benzylcyanide, α- (benzenesulfonyloxyimino) -4-chlorobenzyl Cyanide, α- (benzenesulfonyloxyimino) -2,4-dichlorobenzylcyanide, α- (benzenesulfonyloxyimino) -2,6-dichlorobenzylcyanide, α- (benzenesulfonyloxyimino) 4-methoxybenzyl cyanide, α- (2-chlorobenzenesulfonyloxyimino) -4-methoxybenzyl cyanide, α- (benzenesulfonyloxyimino) -thien-2-ylacetonitrile, α- (4-dodecylbenzenesulfonyloxyimino) -benzyl cyanide, α-[(p-toluenesulfonyloxyimino) -4-methoxyphenyl] acetonitrile, α-[(dodecylbenzenesulfonyloxyimino) -4-methoxyphenyl] acetoni Reel, α- (tosyloxyimino) -4-thienyl cyanide, α- (methylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (methylsulfonyloxyimino) -1-cyclohexenyl Acetonitrile, α- (methylsulfonyloxyimino) -1-cycloheptenylacetonitrile, α- (methylsulfonyloxyimino) -1-cyclooctenylacetonitrile, α- (trifluoromethylsulfonyloxyimino ) -1-cyclopentenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -cyclohexylacetonitrile, α- (ethylsulfonyloxyimino) -ethylacetonitrile, α- (propylsulfonyloxyimino ) -Propylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclopentylacetonitrile, α- (cyclohexylsulfonyloxyimino) -cyclohexylacetonitrile, α- (cyclohexylsulfonyloxyimino) -1 -Cyclopentenyl acetonitrile, α- (ethylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (Isopropylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (n-butylsulfonyloxyimino) -1-cyclopentenylacetonitrile, α- (ethylsulfonyloxyimino) -1-cyclo Hexenyl acetonitrile, α- (isopropylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (n-butylsulfonyloxyimino) -1-cyclohexenylacetonitrile, α- (methylsulfonyl Oxyimino) -phenylacetonitrile, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (trifluoromethylsulfonyloxyimino) -phenylacetonitrile, α- (trifluoromethyl Sulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (ethylsulfonyloxyimino) -p-methoxyphenylacetonitrile, α- (propylsulfonyloxyimino) -p-methylphenylacetonitrile, α- (Methylsulfonyloxyimino) -p-bromophenyl acetonitrile etc. are mentioned. Of these, α- (methylsulfonyloxyimino) -p-methoxyphenylacetonitrile is preferable.

As diazomethane type PAG, arbitrary things can be suitably selected from a conventionally well-known thing, and it is especially represented by the following general formula (V) from a viewpoint of transparency, moderate acid strength, alkali solubility, etc. Bisalkyl or bisarylsulfonyl diazomethanes are used preferably.

In formula (V), R <^3> and R <^4> represents a C3-C8, Preferably 4-7 branched or cyclic alkyl group or an aryl group each independently. As R <^3> and R <^4> , a tert- butyl group, a cyclohexyl group, a phenyl group, etc. can be illustrated more specifically. Among these, a cyclohexyl group is preferable because the rectangularity of the resist pattern obtained further improves and also the resolution improves. As the reason, since the cyclohexyl group is a bulky group, it is thought that the generated acid is difficult to diffuse in the resist.

Specific examples of bisalkyl or bisarylsulfonyldiazomethanes include bis (isopropylsulfonyl) diazomethane, bis (p-toluenesulfonyl) diazomethane and bis (1,1-dimethylethylsulfonyl) dia Crude methane, bis (cyclohexylsulfonyl) diazomethane, bis (2, 4- dimethylphenyl sulfonyl) diazomethane, etc. are mentioned.

As poly (bissulfonyl) diazomethanes, for example, 1,3-bis (phenylsulfonyldiazomethylsulfonyl) propane (when A = 3), 1,4 having a structure shown below -Bis (phenylsulfonyldiazomethylsulfonyl) butane (if A = 4), 1,6-bis (phenylsulfonyldiazomethylsulfonyl) hexane (if A = 6), 1,10-bis (Phenylsulfonyldiazomethylsulfonyl) decane (if A = 10), 1,2-bis (cyclohexylsulfonyldiazomethylsulfonyl) ethane (if B = 2), 1,3-bis ( Cyclohexylsulfonyldiazomethylsulfonyl) propane (if B = 3), 1,6-bis (cyclohexylsulfonyldiazomethylsulfonyl) hexane (if B = 6), 1,10-bis ( Cyclohexylsulfonyl diazommethylsulfonyl) decane (when B = 10) etc. are mentioned.

As the component (B), one type of acid generator may be used alone, or two or more types may be used in combination.

In the present invention, the component (B) preferably contains a diazomethane-based acid generator and / or an onium salt-based acid generator. In particular, the use of at least one diazomethane-based acid generator and at least one onium salt-based acid generator in combination is preferable for obtaining good resolution and rectangularity.

It is preferable that 40-95 mass% of diazomethane-type acid generators are contained in (B) component, More preferably, it is 40-80 mass%, More preferably, it is 40-70 mass%. Most preferably, it is 45-65 mass%. On the other hand, it is preferable that 5-60 mass% of onium salt type acid generators are contained in (B) component, More preferably, it is 10-60 mass%, More preferably, it is 20-60 mass%. Most preferably, it is 30-60 mass%.

It is preferable that the total amount of a diazomethane type acid generator and an onium salt type acid generator is 80 mass% or more in component (B), and 100 mass% may be sufficient as it.

Content of (B) component in a resist composition is 0.5-30 mass parts with respect to 100 mass parts of (A) component, Preferably it is 1-10 mass parts. By setting it as the said range, time-lapse stability after exposure will become favorable. Moreover, pattern formation can fully be performed.

Dissolution Inhibitor (C)

In the positive resist composition of the present invention, as an optional component, at least one acid dissociable, dissolution inhibiting group has a dissolution inhibitor capable of dissociating the dissolution inhibiting group to generate an organic carboxylic acid by the action of an acid generated from the component (B). You may contain (C).

As such a component (C), for example, a phenol derivative having a mass average molecular weight of 200 to 1000 and having 1 to 6 substituted or unsubstituted benzene nuclei is preferable. As a specific example, the compound represented by following General formula (1) is mentioned.

(Wherein R 'is an acid dissociable, dissolution inhibiting group)

The acid dissociable, dissolution inhibiting group R 'can be arbitrarily selected from those known so far for chemically amplified positive resists. Specific examples include tertiary alkyloxycarbonyl groups such as tert-butyloxycarbonyl group and tert-amyloxycarbonyl group; tertiary alkyloxycarbonylalkyl groups such as tert-butyloxycarbonylmethyl group and tert-butyloxycarbonylethyl group; tertiary alkyl groups such as tert-butyl group and tert-amyl group; Cyclic ether groups such as tetrahydropyranyl group and tetrahydrofuranyl group; Preferable alkoxyalkyl groups, such as an ethoxy ethyl group and a methoxypropyl group, are mentioned.

Among them, tert-butyloxycarbonyl group, tert-butyloxycarbonylmethyl group, tert-butyl group, tetrahydropyranyl group, ethoxyethyl group, 1-methylcyclohexyl group and 1-ethylcyclohexyl group are preferable.

However, at least one acid dissociable, dissolution inhibiting group R 'needs to use a carboxylic acid generator such as a tertiary alkyloxycarbonylalkyl group.

(C) component is used in 0.1-50 mass parts with respect to 100 mass parts of (A) components normally, Preferably it is 1-20 mass parts.

<Nitrogen-containing compound (D)>

In order to improve a resist pattern shape, post-exposure time-lapse stability, etc., the nitrogen-containing organic compound (D) can be further mix | blended with the positive type resist composition of this invention.

Since various (1) components of this (D) component are already proposed, what is known may be used arbitrarily, but aliphatic amines, especially secondary aliphatic amine and tertiary aliphatic amine, are preferable.

Examples of the aliphatic amines include amines (alkylamines or alkylalcoholamines) in which at least one hydrogen atom of ammonia NH ₃ is substituted with an alkyl group having 12 or less carbon atoms or a hydroxyalkyl group. As the specific example, Monoalkylamine, such as n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine; Dialkylamines such as diethylamine, di-n-propylamine, di-n-heptylamine, di-n-octylamine, dicyclohexylamine; Trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, tri-n-hexylamine, tri-n-pentylamine, tri-n-heptylamine, tri-n-octylamine, tri trialkylamines such as -n-nonylamine, tri-n-decanylamine and tri-n-dodecylamine; And alkyl alcohol amines such as diethanolamine, triethanolamine, diisopropanolamine, triisopropanolamine, di-n-octanolamine, and tri-n-octanolamine. Among these, alkyl alcohol amine and trialkyl amine are preferable and alkyl alcohol amine is the most preferable. Among the alkyl alcohol amines, triethanolamine and triisopropanolamine are most preferred.

These may be used independently and may be used in combination of 2 or more type.

(D) component is normally used in 0.01-5.0 mass parts with respect to 100 mass parts of (A) component.

<(E) component>

Furthermore, in order to prevent the sensitivity deterioration by mixing with the said (D) component, and to improve resist pattern shape, storage stability, etc., as an arbitrary component, further, an organic carboxylic acid or phosphorus oxo acid or its derivative (E ) (Hereinafter, referred to as component (E)). In addition, (D) component and (E) component may be used together and any 1 type may be used.

As organic carboxylic acid, malonic acid, citric acid, malic acid, succinic acid, benzoic acid, salicylic acid, etc. are preferable, for example.

Examples of phosphorus oxo acids or derivatives thereof include derivatives such as phosphoric acid or esters thereof such as phosphoric acid, di-n-butyl phosphate and diphenyl phosphate, phosphonic acid, phosphonic acid dimethyl ester, phosphonic acid-di-n-butyl ester, Derivatives such as phosphonic acids such as phenylphosphonic acid, phosphonic acid diphenyl ester, phosphonic acid dibenzyl ester and esters thereof, and derivatives such as phosphinic acid such as phosphinic acid and phenylphosphinic acid and esters thereof, among others Phosonic acid is preferred.

(E) component is used in the ratio of 0.01-5.0 mass parts per 100 mass parts of (A) component.

<Other optional ingredients>

The positive resist composition of the present invention may further contain additives that are miscible as desired, for example, additional resins for improving the performance of resist films, surfactants for improving applicability, plasticizers, stabilizers, coloring agents, and halation. An inhibitor etc. can be added and contained suitably.

Organic solvents (S)

The positive resist composition of the present invention can be prepared by dissolving the component (A), the component (B), and optional component (C) described below and any optional components described later in an organic solvent.

It is preferable that (A) component mixes and manufactures the said (A1) component, (A2) component, and other resin component as needed previously.

As an organic solvent, what is necessary is just to be able to melt | dissolve each component to be used and it can be set as a uniform solution, and arbitrary 1 type (s) or 2 or more types can be suitably selected and used out of what is known as a solvent of the conventional chemically amplified resist.

For example, lactones, such as (gamma) -butyrolactone, ketones, such as acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, and 2-heptanone, ethylene glycol, ethylene glycol monoacetate, diethylene glycol, Polyhydric alcohols such as monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether of diethylene glycol monoacetate, propylene glycol, propylene glycol monoacetate, dipropylene glycol or dipropylene glycol monoacetate, and Derivatives thereof, cyclic ethers such as dioxane, esters such as methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate and ethyl ethoxypropionate Etc. can be mentioned.

These organic solvents may be used independently and may be used as 2 or more types of mixed solvents.

Moreover, the mixed solvent which mixed propylene glycol monomethyl ether acetate (PGMEA) and a polar solvent is preferable. The blending ratio (mass ratio) may be appropriately determined in consideration of the compatibility of PGMEA and the polar solvent, and the like, but is preferably in the range of 1: 9-9: 1, more preferably 2: 8-8: 2. Do.

More specifically, when mix | blending EL as a polar solvent, the mass ratio of PGMEA: EL becomes like this. Preferably it is 1: 9-9: 1, More preferably, it is 2: 8-8: 2.

As the organic solvent, a mixed solvent of at least one selected from PGMEA and EL and γ-butyrolactone is also preferable. In this case, as a mixing ratio, the mass ratio of the former and the latter becomes like this. Preferably it is 70: 30-95: 5.

Although the usage-amount of an organic solvent is not specifically limited, Although it sets suitably according to the coating film thickness in the density | concentration which can be apply | coated to a board | substrate etc., it is generally 2-20 mass% of solid content concentration of a resist composition, Preferably it is 5-15 mass% Used to be in range.

<Resist Pattern Forming Method>

The method of forming a resist pattern can be performed as follows, for example.

First, the positive resist composition is coated on a substrate such as a silicon wafer with a spinner or the like, and a resist film is formed by prebaking for 40 to 120 seconds, preferably 60 to 90 seconds under a temperature condition of 80 to 150 ° C. do. Next, the KrF excimer laser light is selectively exposed to the resist film by a KrF exposure apparatus or the like through a desired mask pattern, and then PEB (post-exposure heating) is subjected to 40 to 120 under a temperature condition of 80 to 150 ° C. Seconds, preferably 60 to 90 seconds. Next, this is developed using alkaline developing solution, for example, 0.1-10 mass% tetramethylammonium hydroxide aqueous solution. In this manner, a resist pattern that is faithful to the mask pattern can be obtained.

In addition, an organic or inorganic antireflection film may be formed between the substrate and the coating layer of the resist composition.

The wavelength used for exposure is not particularly limited, and radiations such as ArF excimer laser, KrF excimer laser, F ₂ excimer laser, EUV (extreme ultraviolet), VUV (vacuum ultraviolet), EB (electron beam), X-ray, soft X-ray It can be used. In particular, the photoresist composition according to the present invention is effective for KrF excimer laser.

In this invention, the positive resist composition and the resist pattern formation method which can obtain favorable resolution and a resist pattern shape can be provided. Among the above-mentioned resolutions, the separation resolution (separation margin) is particularly excellent.

Moreover, although the reason is not certain, the line edge roughness [non-uniform unevenness | corrugation of (LER) line side wall] characteristic is also excellent.

The positive resist composition was adjusted to the composition shown in Table 1 below. In Table 1, the numerical value in [] shows a compounding quantity (mass part).

<Explanation of abbreviation> (A1) -1: Resin which consists of a structural unit represented by a following formula.

[In formula, it is a: b: c: d (molar ratio) = 58: 17: 22: 3 (molar ratio), and Ev represents a 1-ethoxyethyl group. Mw = 12000, Mw / Mn = 1.7]

(A2) -1: Resin which consists of a structural unit represented by a following formula.

[Wherein, a: c (molar ratio) is 70:30 (molar ratio), and Ev represents a 1-ethoxyethyl group. Mw = 20000, Mw / Mn = 1.2]

PAG1: triphenylsulfonium nonafluorobutanesulfonate

PAG2: bis (2,4-dimethylphenylsulfonyl) diazomethane

PAG3: bis (cyclohexylsulfonyl) diazomethane

(D) -1: triethanolamine

(D) -2: triisopropanolamine

(C) -1: Dissolution inhibitor represented by the following formula.

ADD1: surfactant XR-104 (manufactured by Dainippon Ink and Chemicals, Inc.)

S1: mixed solvent of PGMEA / EL = 6/4

The board | substrate with which the organic antireflective film (Brewer Science company make, brand name DUV-44) was heated at 225 degreeC for 60 second on the 8-inch silicon wafer, and formed into the film thickness of 65 nm was prepared.

The positive resist composition obtained above was apply | coated using a spinner on the board | substrate, prebaked at 100 degreeC and 60 second on a hotplate, and was dried, and the resist layer of 270 nm thick was formed.

Subsequently, KrF excimer laser (248 nm) was selectively irradiated through the halftone mask by KrF scanner NSR-S203B (made by Nikon, NA (aperture number) = 0.68, 2/3 ring illumination).

Then, PEB treatment was performed under conditions of 110 ° C. and 60 seconds, and further developed at 23 ° C. with a 2.38% by mass tetramethylammonium hydroxide aqueous solution for 60 seconds, followed by water rinsing with pure water for 15 seconds. After shaking-drying, it heated and dried at 100 degreeC for 60 second, and formed the 130-nm line-and-space (L / S) pattern of 1: 1.

The following characteristics were evaluated. The results are summarized in Table 2.

Evaluation method <LER>

With respect to the 130 nm L / S pattern obtained above, 3σ, which is a measure of LER, was determined as an evaluation of the line edge roughness LER in which the line pattern sidewall surface becomes uneven. 3 sigma is the 3rd value (3σ) of the standard deviation ((sigma)) calculated by measuring 32 points of the width | variety of the resist pattern of a sample by measurement SEM (Hitachi Corporation make, brand name "S-9220"). The smaller the value of 3σ, the smaller the roughness and the more uniform the resist pattern was obtained.

<Resolution Evaluation: Separate Margin>

In the selective exposure, a pattern was formed for each exposure amount while starting at an exposure amount smaller than Eop and gradually increasing the exposure time (large exposure amount). And it observed in SEM that the pattern isolate | separates at the time of which exposure amount, and the "separation margin" calculated | required by the formula shown below was shown in Table 2. Larger values indicate better separation resolution.

`` Separated margin '' (%) = 100- (Es / Eop * 100)

Es: Sensitivity when pattern is separated (mJ / cm 2) (energy amount)

Eop: Sensitivity (mJ / cm 2) when forming a 130 nm L / S pattern of 1: 1

<Shape>

About the 130 nm L / S pattern obtained above, the cross-sectional shape was observed with the scanning electron microscope. As a result, the thing with good rectangularity was made into (circle) and the thing with inadequate rectangularity was made into x.

Separate Margin LER shape Example 1 30.6% 4.2 nm ○ Example 2 30.6% 3.9 nm ○ Example 3 30.6% 4.3 nm ○ Comparative Example 1 27.8% 5.1 nm ○ Comparative Example 2 28.6% 4.9 nm ×

From the result of the said Examples 1-3 and Comparative Examples 1-2, it turned out that the resolution and resist pattern shape are excellent by using together (A1) component and (A2) component as a base resin of a resist composition. In addition, excellent results were obtained for LER.

INDUSTRIAL APPLICABILITY The present invention is applicable to a positive resist composition used in a lithography technique in the manufacture of a semiconductor element or a liquid crystal display element, and a resist pattern forming method using the same.

Claims (8)

As a positive resist composition containing the resin component (A) which alkali solubility increases by the action of an acid, and the acid generator component (B) which generate | occur | produces an acid by exposure, 1st structural unit (a1) in which the said resin component (A) is derived from hydroxy styrene, 2nd structural unit (a2) derived from (meth) acrylic acid ester which has an alcoholic hydroxyl group, and the structure derived from hydroxystyrene A fourth in which the alcoholic hydroxyl group of the structural unit derived from the (meth) acrylic acid ester having a hydroxyl group of the unit protected by an acid dissociable dissolution inhibiting group and / or an alcoholic hydroxyl group is protected by an acid dissociable dissolution inhibiting group 1st resin component (A1) which has a structural unit (a4), Second resin component (A2) comprising only the fifth structural unit (a5) derived from hydroxystyrene and the sixth structural unit (a6) in which the hydroxyl group of the structural unit derived from hydroxystyrene is protected with an acid dissociable, dissolution inhibiting group. Including, Furthermore, the mass ratio of the said 1st resin component (A1) and the said 2nd resin component (A2) is (A1) :( A2) = 9: 1-4: 6, The positive resist composition characterized by the above-mentioned. delete The method of claim 1, The positive resist composition in which the acid generator component (B) contains a diazomethane-based acid generator and / or an onium salt-based acid generator. The method of claim 1, Furthermore, the positive resist composition containing a nitrogen containing organic compound (D). The method of claim 1, Furthermore, the positive resist composition containing a dissolution inhibitor (C). A resist pattern forming method comprising the step of forming a resist film on a substrate using the positive resist composition according to claim 1, the step of exposing the resist film, and the step of developing the resist film to form a resist pattern. The method of claim 1, The said resin component (A1) is the following general formula (I)

In the formula, R is a hydrogen atom or a methyl group, m represents an integer of 1 to 3 derived from the first structural unit (a1) derived from hydroxystyrene and (meth) acrylic acid ester having an alcoholic hydroxyl group As a 2nd structural unit (a2), following General formula (II)

A structural unit derived from an adamantyl group-containing (methyl) acrylic acid ester having at least one alcoholic hydroxyl group represented by [wherein R represents a hydrogen atom or a methyl group, x represents an integer of 1 to 3], The hydroxyl group of the structural unit derived from the hydroxystyrene represented by the said general formula (I) is protected by the acid dissociable, dissolution inhibiting group, and / or the alcoholic hydroxyl group of the structural unit represented by the said general formula (II) The positive resist composition which has a 4th structural unit (a4) protected by the acid dissociable, dissolution inhibiting group. The method of claim 1, Furthermore, it has at least 1 acid dissociable, dissolution inhibiting group, and the dissolution inhibiting group can be dissociated by the action of the acid generated in the component (B) to generate organic carboxylic acid, Positive resist composition containing the dissolution inhibitor (C) which consists of a phenol derivative which has a mass mean molecular weight 200-1000, and has 1-6 substituted or unsubstituted benzene nuclei.