CN1853140B - Positive resist composition and method for forming resist pattern - Google Patents

Abstract

A positive resist composition comprising (A) a resin ingredient which has acid-dissociable dissolution-inhibitive groups and comes to have enhanced alkali solubility by the action of an acid and (B) an acid generator ingredient which generates an acid upon exposure to light, wherein the resin ingredient (A) is a copolymer (A1) which comprises first structural units (a1) derived from hydroxystyrene and second structural units (a2) derived from a (meth)acrylic ester having an alcoholic hydroxy group and in which part of the hydroxy groups of the structural units (a1) and of the alcoholic hydroxy groups of the structural units (a2) have been protected by the acid-dissociable dissolution-inhibitive groups. The acid generator ingredient (B) comprises a diazomethane type acid generator and an onium salt type acid generator, or the composition further contains a compound which has at least one acid-dissociable dissolution-inhibitive group and can generate an organic carboxylic acid by the action of the acid generated from the ingredient (B).

Description

Positive resist composition and method for forming resist pattern

technical field

The present invention relates to a positive type resist composition and a method for forming a resist pattern. The present invention claims Japanese Patent Application No. 2003-326146 filed on September 18, 2003 and Japanese Patent Application No. 2003-331606 filed on September 24, 2003 and Japanese Patent Application No. 2003-331606 filed on April 14, 2004. Priority of .2004-119494, the contents of which are hereby incorporated by reference.

Background technique

In recent years, developments in photolithography have led to rapid progress in miniaturization in the production of semiconductor elements and liquid crystal display elements. Typically, these miniaturization techniques involve shortening of the exposure source wavelength. Until recently, ultraviolet rays such as g-line and i-line have been used as exposure sources, however, recently KrF excimer lasers (248 nm) have been introduced and even ArF excimer lasers (193 nm) are now being used.

An example of a resist material that satisfies high-resolution conditions required to be able to reproduce minute-sized patterns is a chemically amplified resist composition comprising a base resin and an acid generator dissolved in an organic solvent, the base resin The change of alkali solubility occurs under the action of acid, and the acid generator generates acid by exposure.

Chemically amplified resist compositions that have been proposed as ideal resist materials for methods in which exposure is performed using a KrF excimer laser typically use polyhydroxystyrene-based resins in which acid-dissociable, soluble An inhibiting group serves as a base resin to protect part of hydroxyl groups (for example, see Patent Reference 1).

Examples of the most commonly used acid-cleavable, dissolution-inhibiting groups include so-called acetal groups, including chain ether groups represented by 1-ethoxyethyl and tetrahydropyranyl groups a cyclic ether group, and a tert-alkyl group represented by a t-butyl group and a tert-alkoxycarbonyl group represented by a t-butoxycarbonyl group.

On the other hand, in addition to research into resist materials capable of ultra-miniaturization, research and development of patterning methods are being conducted to develop technologies capable of overcoming the resolution limitation of resist materials.

An example of such a miniaturization technique recently proposed is a heat flow method in which a resist pattern is formed using a usual photolithography technique and then heat-treated to reduce the pattern size (for example, see Patent References 2 and 3).

Heat flow is a method in which, after a resist pattern is formed using a photolithography technique, the resist pattern is heated and softened, causing the pattern to flow toward a gap in the pattern, thereby reducing the size of the resist pattern, that is, no resist pattern is formed. The size of the portion of the agent (eg, hole diameter in a hole pattern, or space width in a line and space (L&S) pattern).

(Patent Reference 1)

Japanese Unexamined Patent Application, First Publication No.Hei 4-211258

(Patent Reference 2)

Japanese Unexamined Patent Application, First Publication No.2000-188250

(Patent Reference 3)

Japanese Unexamined Patent Application, First Publication No.2000-356850

In recent years, as the speed of miniaturization has accelerated, further improvement in the resolution of resist materials is now required.

However, the above-mentioned conventional polyhydroxystyrene-based resins can no longer be required to provide sufficient resolution. In addition, the degree of rectangle is not good in the cross-sectional shape of the resist pattern, and its problems include poor verticality of the resist pattern sidewall and rounding of the top shape of the resist pattern such as a line and space (L&S) pattern . These problems of squareness become particularly pronounced in the heat flow method, where the resist pattern is heated and causes post-development flow.

Furthermore, the inventors of the present invention made the following findings by investigating the improvement of resolution using a wide range of different materials. That is, in a copolymer comprising a structural unit derived from hydroxystyrene and a structural unit derived from (meth)acrylate having an alcoholic hydroxyl group in which a part of the hydroxyl group has been protected by an acid-dissociable, dissolution-inhibiting group is In those cases where resin components that are resist materials are used, the increased protection ratio provided by the acid-cleavable, dissolution-inhibiting groups improves resolution. However, such an increased protection ratio tends to increase the occurrence of development defects such as development residue. The occurrence of development defects is disadvantageous, which can become a significant problem in the production of semiconductor elements.

Contents of the invention

Accordingly, an object of the present invention is to provide a positive resist composition capable of preparing a resist pattern having excellent resolution and favorable rectangularity, a positive resist composition that resists the development of development defects while retaining excellent resolution. A resist composition, and a method of forming a resist pattern using the positive resist composition.

The first aspect of the present invention to achieve the above objects is a positive resist composition comprising a resin component (A) containing an acid-dissociable, dissolution-inhibiting group and exhibiting enhanced alkali solubility under the action of an acid and an acid generator component (B) that generates an acid by exposure, wherein

The resin component (A) is a copolymer ( A1), wherein the hydroxyl group of the structural unit (a1) and the alcoholic hydroxyl group of the structural unit (a2) have been protected by an acid-dissociable, dissolution-inhibiting group, and

The acid generator component (B) includes a diazomethane acid generator and an onium salt-based acid generator.

The second aspect of the present invention to achieve the above-mentioned object is a positive resist composition comprising a resin component (A) containing an acid-dissociable, dissolution-inhibiting group and exhibiting enhanced alkali solubility under the action of an acid and an acid generator component (B) that generates an acid by exposure, wherein

The resin component (A) is a copolymer (A1) comprising a first structural unit (a1) derived from hydroxystyrene and a second structural unit (a2) derived from a (meth)acrylate having an alcoholic hydroxyl group, A moiety wherein the hydroxyl group of structural unit (a1) and the alcoholic hydroxyl group of structural unit (a2) have been protected by an acid-cleavable, dissolution-inhibiting group; and

The composition also comprises a compound (C), said compound (C) containing at least one acid-dissociable, dissolution-inhibiting group and under the action of an acid generated from component (B), said dissolution-inhibiting group The group dissociates to form an organic carboxylic acid.

The third aspect of the present invention that achieves the above object is a method for forming a resist pattern, the method comprising the steps of: forming a positive resist film on top of a substrate using the positive resist composition described above, The positive type resist film is subjected to selective exposure treatment and alkaline development to form the resist pattern.

A fourth aspect of the present invention is a method of forming a resist pattern, the method comprising the steps of: forming a positive resist film on top of a substrate using the positive resist composition according to the second aspect of the present invention, The positive type resist film is subjected to selective exposure treatment and alkaline development to form the resist pattern.

In the present invention, the term "(meth)acrylic" is a general term including methacrylate and acrylate. The term "structural unit" refers to a monomeric unit that contributes to the formation of a polymer.

(Effect of the present invention)

A first aspect of the present invention provides a positive resist composition capable of producing excellent resolution and favorable rectangularity, and a method of forming a resist pattern using the positive resist composition.

A second aspect of the present invention provides a positive resist composition which is resistant to the development of development defects, particularly scum, while retaining excellent resolution, and a positive resist composition formed using the positive resist composition. Method of resist patterning.

Best Mode for Carrying Out the Invention

The following is a more detailed description of the invention.

<<Positive resist composition>>

[Positive resist composition embodiment 1 (positive resist composition of the first aspect of the present invention)]

The positive resist composition of the first aspect of the present invention comprises a resin component (A) containing an acid-dissociable, dissolution-inhibiting group and exhibiting enhanced alkali solubility under the action of an acid (hereinafter referred to as component (A) )) and an acid generator component (B) that generates acid by exposure (hereinafter referred to as component (B)).

In component (A), the action of the acid generated from component (B) causes the dissociation of the acid-dissociable, dissolution-inhibiting group, thereby causing the entirety of component (A) to change from an alkali-insoluble state to an alkali-soluble state .

As a result, when the resist is exposed through a mask pattern during resist pattern formation, or alternatively exposed and then post-exposure baked, the exposed portions of the resist become alkali-soluble while the unexposed portions remain in the alkali-soluble state. Moderately insoluble, meaning that alkali development can then be used to form a positive tone resist pattern.

<Component (A)>

In the present invention, component (A) is composed of, as basic structural units, a first structural unit (a1) derived from hydroxystyrene and a second structural unit derived from (meth)acrylate having an alcoholic hydroxyl group A copolymer of (a2) (hereinafter referred to as copolymer (A1)), wherein the hydroxyl groups of the first structural unit (a1) and the hydroxyl groups of the second structural unit (a2) have been protected by acid-cleavable, dissolution-inhibiting groups. Alcoholic hydroxyl moiety.

This copolymer (A1) may further include a third structural unit (a3) derived from styrene in addition to the first structural unit (a1) and the second structural unit (a2).

[First structural unit (a1)]

The first structural unit (a1) is a structural unit derived from hydroxystyrene, and is represented by the general formula (I) shown below. In other words, in this description, the name hydroxystyrene describes both the intended hydroxystyrene and α-methylhydroxystyrene.

In the structural unit (a1) represented by the general formula (I) shown below, the bonding position of the hydroxyl group may be the ortho-position, the meta-position or the para-position, but considering availability and cost, it is preferable to - bit.

(where R represents a hydrogen atom or a methyl group)

[Second structural unit (a2)]

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

As a result of the inclusion of the structural unit (a2), the copolymer (A1) is less soluble in alkaline developing solutions than conventional resins (hereinafter also referred to as PHS resins) in which acid-dissociable, soluble Inhibiting groups protect part of the hydroxyl groups of polyhydroxystyrene.

In other words, in conventional PHS resins, all units other than those protected by acid-cleavable, dissolution-inhibiting groups are structural units derived from hydroxystyrene (hereinafter also referred to as hydroxystyrene units). The hydroxyl groups of the hydroxystyrene units are phenolic hydroxyl groups. On the contrary, the copolymer (A1) contains a structural unit capable of introducing alcoholic hydroxyl group (structural unit (a2), which has lower alkali solubility than phenolic hydroxyl group, said structural unit becomes the base resin instead of the above hydroxystyrene unit part of the side chain. As a result, the solubility of the copolymer (A1) in the alkaline developing solution is lower than that of the PHS resin. This means that the protection ratio can be reduced, the defect level can be reduced, and the resolution can be improved.

Therefore, assuming that the structural unit (a2) of the present invention exhibits such an effect, there is no particular limitation on the structural unit, and any structural unit derived from (meth)acrylate having an alcoholic hydroxyl group can be used, although derived from The structural unit of (meth)acrylate having an aliphatic polycyclic group having an alcoholic hydroxyl group exhibits particularly excellent resolution and dry etching resistance, and thus is preferable.

Examples of the polycyclic group constituting the above-mentioned aliphatic polycyclic group having an alcoholic hydroxyl group include groups in which one hydrogen atom has been removed from bicycloalkane, tricycloalkane or tetracycloalkane or the like. Specific examples include groups in which one hydrogen atom has been removed from polycyclic alkanes such as adamantane, norbornane, isobornane, tricyclodecane or tetracyclododecane. These types of polycyclic groups can be suitably selected from the numerous groups suggested for conventional ArF resists. Among these groups, adamantyl, norbornyl and tetracyclododecyl are industrially preferred.

As the structural unit (a2), a structural unit derived from a (meth)acrylate containing an adamantyl group having at least one alcoholic hydroxyl group, as represented by the general formula (II) shown below, can be used particularly favorably.

Among the structural units (a2) represented by the general formula (II) shown below, the structural unit represented by the general formula (IIa) shown below is most desirable.

(wherein, R represents a hydrogen atom or a methyl group, and x represents an integer of 1 to 3.)

[acid-cleavable, dissolution-inhibiting group]

In the copolymer (A1), some of the hydroxyl groups of the first structural unit (a1) and the alcoholic hydroxyl groups of the second structural unit (a2) must be protected by acid-cleavable, dissolution-inhibiting groups.

As for the acid-dissociable, dissolution-inhibiting groups, numerous acid-dissociable, dissolution-inhibiting groups suggested for conventional chemically amplified KrF positive resist compositions or ArF positive resist compositions can be used Any of these, and specific examples include chain or ring tertiary alkyl groups such as tert-butyl, tert-pentyl, 1-methylcyclopentyl, 1-ethylcyclopentyl, 1-methylcyclohexyl and 1 - ethylcyclohexyl, cyclic ether groups such as tetrahydropyranyl and tetrahydrofuryl, and 1-lower alkoxyalkyl represented by the general formula (III) shown below, wherein the 1-position consists of 1 to 8 Straight-chain, branched-chain or cyclic alkoxyalkyl substituted carbon atoms. Among these groups, 1-lower alkoxyalkyl groups represented by the general formula (III) are particularly preferred. Specific examples of these groups include linear and branched alkoxyalkyl groups such as 1-ethoxyethyl and 1-isopropoxyethyl, and cycloalkoxyalkyl groups such as 1-cyclohexyloxyethyl groups, and among these, 1-ethoxyethyl groups are particularly desirable because they provide excellent resolution.

(Wherein, R ¹ represents an alkyl group of 1 to 4 carbon atoms, R ² represents a linear or branched chain alkyl group of 1 to 8 carbon atoms, or a cycloalkyl group of 5 to 7 carbon atoms)

In the present invention, the hydroxyl group protection ratio in the copolymer (A1) is preferably in the range of at least 10 mol% to not more than 25 mol%, the hydroxyl group in the structural unit (a1) and the alcohol formula in the structural unit (a2) The combined total of hydroxyl groups is preferably in the range of at least 15 mole percent to no more than 20 mole percent.

Ensuring that the hydroxyl protection ratio does not exceed the upper limit of the above range can achieve favorable rectangularity of the developed resist pattern. In addition, pattern defects (development defects) in the resist pattern after development can also be effectively prevented. On the other hand, ensuring that the hydroxyl protection ratio is at least as large as the lower limit of the above range can achieve favorable resolution performance.

In the copolymer (A1), the hydroxyl group protected by the acid-dissociable, dissolution-inhibiting group may be the hydroxyl group of the structural unit (a1) or the alcoholic hydroxyl group of the structural unit (a2), and is not particularly limited, but preferably is a copolymer in which only the hydroxyl group (hydroxystyrene phenolic hydroxyl group) of the structural unit (a1) is protected by an acid-dissociable, dissolution-inhibiting group, or in which the structure is simultaneously protected by an acid-dissociable, dissolution-inhibiting group A copolymer of the hydroxyl group of the unit (a1) and the alcoholic hydroxyl group of the second structural unit (a2). In addition, although depending on the acid-dissociable, dissolution-inhibiting group used, the protection of the hydroxyl group of the structural unit (a1) and the alcoholic hydroxyl group of the structural unit (a2) by the acid-dissociable, dissolution-inhibiting group The situation is usually the most preferred.

In copolymer (A1), the molar ratio between copolymer structural units (a1) and structural units (a2) before protection by acid-dissociable, dissolution-inhibiting groups is preferably 85:15 to 70:30 , more preferably 82:18 to 78:22.

If the proportion of the structural unit (a2) exceeds the above range, the solubility of the copolymer in a developing solution is insufficient, but if the proportion is too small, the effect achieved by using the structural unit (a2) is not sufficiently developed.

Furthermore, in the copolymer (A1), the combination of the structural unit (a1) and the structural unit (a2) preferably accounts for all the structural units constituting the copolymer (A1) before protection by an acid-cleavable, dissolution-inhibiting group of at least 90 mole percent. If the ratio is lower than 90%, the resolution tends to deteriorate. The proportion of the copolymer composed of the combination of the structural unit (a1) and the structural unit (a2) is even more preferably 95 mol% or more, and may also be 100 mol%.

[Third structural unit (a3)]

The structural unit (a3) is a structural unit derived from styrene, and is represented by the general formula (IV) shown below. In other words, in this description, the name styrene refers to the original meaning of styrene as well as α-methylstyrene.

(where R represents a hydrogen atom or a methyl group)

In the present invention, the structural unit (a3) is not essential, however, the inclusion of such a structural unit provides certain benefits such as improved depth of focus and improved dry etching resistance.

If the third structural unit (a3) is used, the proportion of the structural unit (a3) in the copolymer (A1) is preferably 0.5 to 10 mol %, even more preferably 2 to 5 mol%. If the proportion of the structural unit (a3) exceeds the above range, the solubility of the copolymer in a developing solution tends to deteriorate.

In copolymer (A1), the weight-average molecular weight of the copolymer (polystyrene equivalent value determined using gel permeation chromatography, which is also valid for all Molecular weight value below) is preferably at least 2,000 but not more than 8,500, even more preferably at least 4,500 but not more than 8,500. Provided that the weight average molecular weight is not more than 8,500, the rectangularity of the resist pattern can be improved. In addition, the generation of microbridges can also be prevented. Furthermore, provided that the weight average molecular weight is at least 2,000, etch resistance and heat resistance are favorable.

In this description, the term "microbridge" describes this type of development defect in which line-and-space patterns, for example, portions of adjacent resist patterns near the surface of the pattern, are linked together by parts of the resist, resulting in a bridge-like defect. For higher weight average molecular weight values, and for higher temperatures within the post-exposure bake (PEB), microbridges are increasingly possible.

Furthermore, the copolymer is preferably a monodisperse system with low polydispersity (Mw/Mn ratio) before the hydroxyl moieties are protected by acid-cleavable, dissolution inhibiting groups, as it provides excellent resolution.

Specifically, the polydispersity typically does not exceed 2.0, more preferably 1.5 or less.

For example, the copolymer (A1) can be prepared by using a usual method such as a conventional method using a radical initiator such as azobisisobutyronitrile (AIBN) or azobis(2-methylpropionate). A radical polymerization method in which a monomer corresponding to the structural unit (a1) in which the hydroxyl group is not protected and a monomer corresponding to the structural unit (a2) in which the hydroxyl group is not protected are copolymerized, and then converted from an acid by using a known technique Dissociative, dissolution-inhibiting groups protect the hydroxyl groups of structural unit (a1) and/or structural unit (a2).

In addition, the copolymer (A1) can also be prepared by preparing a monomer corresponding to a structural unit obtained by protecting the hydroxyl group of the structural unit (a1) with an acid-cleavable, dissolution-inhibiting group, and converting this A monomer is copolymerized with a monomer corresponding to the structural unit (a2), and then using hydrolysis to change part of the hydroxyl groups that have been protected by acid-cleavable, dissolution-inhibiting groups back to hydroxyl groups, and if necessary, then using the usual method by The acid-cleavable, dissolution-inhibiting group protects the hydroxyl group of structural unit (a2).

The amount of the copolymer (A1), that is, the amount of the component (A) in the positive resist composition of the present invention can be adjusted according to the thickness of the resist film to be formed.

<Component (B)>

In the present invention, as component (B), a combination of at least one diazomethane-based acid generator and at least one onium-based acid generator is used. By combining the above-mentioned component (A) with such an acid generator mixture, a resist pattern exhibiting high resolution and favorable rectangularity can be formed.

As for the diazomethane-based PAG, any compound suitably selected from conventional materials can be used, and among these compounds, the compound represented by the general formula (V) shown below in consideration of transparency, suitable acid strength, alkali solubility, etc. For example bis(hydroxysulfonyl)diazomethane is particularly desirable:

In formula (V), R ³ and R ⁴ each independently represent a branched or cyclic alkyl or aryl group of 3 to 8 carbon atoms, preferably 4 to 7 carbon atoms. Specific examples of ^R3 and ^R4 include tert-butyl, cyclohexyl or phenyl. Among these, the cyclohexyl group produces better improvement in the rectangularity of the resist pattern and further improvement in the resolution, and is therefore preferable. The reason for the preference is believed to be because the cyclohexyl group is a bulky group, inhibiting the diffusion of the generated acid through the resist.

Specific examples of bis(hydroxysulfonyl)diazomethane include: bis(alkylsulfonyl)diazomethane containing a linear or branched chain alkyl group of 1 to 4 carbon atoms, such as bis(n-propylsulfonyl) Diazomethane, bis(isopropylsulfonyl)diazomethane, bis(n-butylsulfonyl)diazomethane, bis(isobutylsulfonyl)diazomethane, bis(tert-butylsulfonyl)diazo Methane and bis(1,1-dimethylsulfonyl)diazomethane; bis(alkylsulfonyl)diazomethane containing cycloalkyl groups of 5 to 6 carbon atoms, such as bis(cyclopentylsulfonyl) diazomethane and bis(cyclohexylsulfonyl)diazomethane; and bis(arylsulfonyl)diazomethane containing aryl groups, such as bis(m-toluenesulfonyl)diazomethane and bis(2,4-bis Methylphenylsulfonyl) diazomethane. Among these, bis(cyclohexylsulfonyl)diazomethane is preferable because it gives a large improvement in rectangularity and is capable of forming a high-resolution resist pattern.

These compounds of component (B) may be used alone, or two or more different compounds may be used in combination.

Specific examples of onium salt-based acid generators include: diphenyliodonium trifluoromethanesulfonate, (4-methoxyphenyl)phenyliodonium trifluoromethanesulfonate, bis(m-tert-butyl Phenyl)iodonium trifluoromethanesulfonate, triphenylsulfonium trifluoromethanesulfonate, (4-methoxyphenyl)diphenylsulfonium trifluoromethanesulfonate, (4-methylphenyl ) diphenylsulfonium nonafluorobutanesulfonate, (m-tert-butylphenyl) diphenylsulfonium trifluoromethanesulfonate, diphenyliodonium nonafluorobutanesulfonate, bis(m- tert-butylphenyl)iodonium nonafluorobutanesulfonate and triphenylsulfonium nonafluorobutanesulfonate. Among these, onium salts containing fluorinated alkylsulfonate ions as anions are preferred. These onium salt-based acid generators may be used alone, or two or more different materials may be used in combination.

In component (B), the diazomethanelic acid generator is preferably the main component. Describing the diazomethane-acid generator as the main component means that in component (B), the compounding amount of the diazomethane-acid generator is the largest.

In component (B), the compounding amount of the diazomethanelic acid generator is preferably 40 to 95% by weight, more preferably 50 to 90% by weight, even more preferably 55 to 90% by weight, most preferably 80 to 90% by weight In the range.

On the other hand, the compounding amount of the onium salt-based acid generator in component (B) is preferably 5 to 60% by weight, more preferably 10 to 50% by weight, even more preferably 10 to 45% by weight, most preferably 10 to 20% by weight. in the weight percent range.

In the present invention, component (B) may also include other materials typically used as acid generators in conventional chemically amplified resists other than diazomethane-based acid generators and onium-based acid generators, although for To maximize the effect of the present invention, the combination of the diazomethanelic acid generator and the onium base acid generator preferably accounts for at least 80% by weight of component (B), and may also be 100%.

Component (B) is typically used in an amount in the range of 1 to 20 parts by weight, preferably 2 to 10 parts by weight, per 100 parts by weight of component (A). If the amount is below the above range, pattern formation is not performed satisfactorily, but if the amount exceeds the above range, it is difficult to achieve a uniform solution, and there is a risk that the storage stability of the composition deteriorates.

<Nitrogen-containing compound D)>

In the positive resist composition of the present invention, in order to improve the resist pattern shape including rectangularity and the post-exposure stability of the latent image formed by patterned exposure of the resist layer, a nitrogen-containing organic compound (D ) (hereinafter referred to as component (D)) as an optional component.

A large number of these organic compounds have been proposed and any of these known compounds may be used as component (D), although amines, especially lower aliphatic secondary amines or lower aliphatic tertiary amines are preferred.

Here, lower aliphatic amines refer to alkylamines or alkanolamines having no more than 5 carbon atoms, examples of these secondary and tertiary amines include trimethylamine, diethylamine, triethylamine, di-n-propylamine, tri-n-propylamine, Propylamine, Triisopropylamine, Tripentylamine, Diethanolamine, and Triethanolamine. Among these, tertiary alkanolamines such as triethanolamine are particularly preferred.

These compounds may be used alone, or two or more different compounds may be used in combination.

Component (D) is typically used in an amount of 0.01 to 5.0% by weight relative to component (A).

<Crosslinking agent (E)>

In those cases where the positive resist composition of the present invention is used in a method in combination with heat flow treatment described below, the positive resist composition of the present invention may further include a crosslinking agent (E) (hereinafter referred to as component (E)).

This component (E) reacts with component (A) by heating and produces crosslinking. By adding component (E), the rectangularity of the resist pattern can be further improved when heat flow treatment is performed.

As component (E), any material known as a suitable crosslinking agent for chemically amplified resist compositions suitable for heat flow treatment may be used.

Specifically, as component (E), compounds containing at least two crosslinked vinyl ether groups can be used, and examples include compounds in which polyoxyalkylene glycols or polyols are substituted with vinyl ether groups At least two hydroxyl groups, the polyoxyalkylene glycol such as alkylene glycol, dialkylene glycol and trialkylene glycol, the polyhydric alcohol such as trimethylolpropane, pentaerythritol or 2, 2-Dimethylpropanediol. A specific example of a preferred component (E) is cyclohexyldimethanol divinyl ether.

Component (E) may be used alone, or two or more different compounds may be used in combination.

If used, the amount of component (E) is typically in the range of 0.1 to 25% by weight, preferably 1 to 15% by weight relative to component (A).

<Other optional components>

Other miscible additives may also be added to the positive resist composition of the present invention as needed, and examples include additive resins for improving resist film properties, surfactants for improving coating easiness, dissolving Inhibitors, plasticizers, stabilizers, colorants and antihalation agents. Of these, the addition of dissolution inhibitors yields additional improvements in resolution and squareness and is therefore preferred.

<Organic solvent>

It can be obtained by dissolving basic components (A) and (B) in an organic solvent, or component (A), component (B), component (C), and if necessary, components (D) and (E) and Any other optional components to prepare the positive resist composition according to the present invention.

The organic solvent may be any solvent capable of dissolving each component used to produce a uniform solution, and one or more solvents selected from known materials used as solvents for conventional chemically amplified resists may be used.

Examples of the organic solvent include those listed below. Namely, ketones such as acetone, methyl ethyl ketone, cyclohexanone, methyl isoamyl ketone, and 2-heptanone; polyhydric alcohols and their derivatives such as 1,2-ethylene glycol, ethylene glycol- Acetate, Diethylene Glycol, Diethylene Glycol Monoacetate, Propylene Glycol, Propylene Glycol Monoacetate, Dipropylene Glycol or Monomethyl Ether of Dipropylene Glycol Monoacetate, Monoethyl Ether, Monopropyl base ether, monobutyl ether or monophenyl ether; cyclic ethers such as dioxane; and esters such as methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, Ethyl pyruvate, methyl methoxypropionate and ethyl ethoxypropionate. These organic solvents may be used alone, or a mixed solvent containing two or more different solvents.

Specifically, a mixed solvent of propylene glycol monomethyl ether acetate (PGMEA) and a polar solvent containing hydroxyl or lactone such as propylene glycol monomethyl ether (PGME), ethyl acetate (EL) or γ-butyrolactone provides positive An improved level of storage stability of the resist composition is therefore preferred. In the case of a mixed solvent containing EL, it is preferable that the weight ratio of PGMEA:EL is in the range of 6:4 to 4:6.

In those cases where PGME is added, typical weight ratios of PGMEA:PGME are in the range of 8:2 to 2:8, preferably 8:2 to 5:5.

There is no particular limitation on the amount of the organic solvent used, although typically, enough solvent is added to obtain a solid fraction concentration of 8 to 25% by weight, preferably 10 to 20% by weight.

[Positive resist composition embodiment 2 (positive resist composition of the second aspect of the present invention)]

Embodiment 2 of the positive resist composition of the present invention comprises: a resin component (A) (hereinafter referred to as component ( A), in the same manner as Embodiment 1 of the positive resist composition), the generator component (B) that generates acid by exposure (hereinafter referred to as component (B), implemented with the positive resist composition Scheme 1 in the same manner), and compound (C) (hereinafter referred to as component (C)), said compound (C) contains at least one acid dissociable, dissolution inhibiting group, and the compound Under the action of the acid generated in component (B), the dissolution inhibiting group dissociates to generate an organic carboxylic acid.

As for component (A), the action of the acid generated from component (B) causes the dissociation of the acid-dissociable, dissolution-inhibiting group, thereby causing the entirety of component (A) to change from an alkali-insoluble state to an alkali-soluble state.

As a result, when the resist is exposed through a mask pattern during resist pattern formation, or alternatively, when exposure is followed by a post-exposure bake, the exposed portion of the resist becomes an alkali-soluble state, while the unexposed portion retains the alkali Insoluble, meaning that alkali development can then be used to form a positive tone resist pattern.

The above description for Embodiment 1 of the positive resist composition described above can also be applied to component (A), component (D), component (E) and other components and organic components of this embodiment. solvent.

<Component (B)>

In the positive resist composition Embodiment 2, as the component (B), a compound suitably selected from known materials used as acid generators in conventional chemically amplified resists can be used.

Among possible acid generators, diazomethanelic acid generators and onium salt-based acid generators are preferred. Specific examples of these acid generators include the same compounds listed in Embodiment 1 with respect to the positive resist composition described above.

As for component (B), a single acid generator may be used alone, or two or more different compounds may also be used in combination.

Component (B) is typically used in an amount of 1 to 20 parts by weight, preferably 2 to 10 parts by weight, per 100 parts by weight of component (A). If the amount is below the above range, pattern formation is not performed satisfactorily, while if the amount exceeds the above range, it is difficult to achieve a uniform solution, with a risk of deterioration in storage stability of the composition.

<Component (C)>

By adding component (C), development defects, especially development residues can be suppressed while maintaining a favorable level of resolution. As a result, very fine resist patterns can be resolved.

There is no particular limitation on the component (C), which can use, for example, one of many compounds proposed in: Japanese Unexamined Patent Application, First Publication No. Hei 6-287163, Japanese Unexamined Patent Application, No. First Publication No.Hei 7-285918, Japanese Unexamined Patent Application, First Publication No.Hei 8-193052, Japanese Unexamined Patent Application, First Publication No.Hei8-193054, Japanese Unexamined Patent Application, No. Primary Publication No. Hei 8-193055, Japanese Unexamined Patent Application, First Publication No. Hei 8-245515, or Japanese Unexamined Patent Application, First Publication No. Hei 9-77720.

The acid-cleavable, dissolution-inhibiting groups may be suitably selected from those known from conventional chemically amplified resists, and these groups can be divided into two main types: A group for those cases of a phenolic hydroxyl group protected by a dissociated, dissolution inhibiting group, and a group for those cases of a carboxyl group protected by an acid cleavable, dissolution inhibiting group.

Specific examples of these types of acid-cleavable, dissolution-inhibiting groups include: tertiary alkoxycarbonyl such as tert-butoxycarbonyl or tert-amyloxycarbonyl; tertiary alkoxycarbonylalkyl such as tert-butoxycarbonylmethyl; or tert-butoxycarbonylethyl; tertiary alkyl such as tert-butyl or tert-amyl; cyclic ether such as tetrahydropyranyl or tetrahydrofuryl; alkoxyalkyl such as ethoxyethyl or methoxy Propyl; and 1-alkylcycloalkyl, including 1-lower alkyl monocycloalkyl such as 1-methylcyclohexyl or 1-ethylcyclohexyl, and 1-lower alkyl polycycloalkyl such as 1- Methyladamantyl or 1-ethyladamantyl.

Among these, tert-butoxycarbonyl, tert-butoxycarbonylmethyl, tert-butyl, tetrahydropyranyl, ethoxyethyl, 1-methylcyclohexyl or 1-ethylcyclohexyl are preferred.

Suitable examples of acid-cleavable, dissolution-inhibiting groups for phenolic hydroxyl groups include all of the above acid-cleavable, dissolution-inhibiting groups except 1-alkylcycloalkyl. Suitable examples of acid-cleavable, dissolution-inhibiting groups for the carboxyl group include all of the above acid-cleavable, dissolution-inhibiting groups except tertiary alkoxycarbonyl groups.

Component (C) must undergo dissociation of acid-cleavable, dissolution-inhibiting groups and formation of organic carboxylic acids under the action of the acid formed from component (B). Therefore, in those cases where component (C) is prepared from a carboxyl-free phenolic compound, at least one of the phenolic hydroxyl groups must be protected using a carboxylic acid generating group such as t- Alkoxycarbonylalkyl.

Furthermore, in those cases where component (C) is prepared from a compound containing at least one carboxyl group, any one of the above-mentioned dissolution-inhibiting groups can be selected by protecting the carboxyl group with the above-mentioned dissolution-inhibiting group.

Particularly preferable examples of the component (C) include phenol derivatives (c-1) having a weight average molecular weight of 200 to 1,000, preferably 600 to 900, in view of achieving high level resolution and favorable resist pattern shape at low cost , and a copolymer (c-2) containing at least 2 mol% of structural units derived from (meth)acrylic acid having an acid-dissociable, dissolution-inhibiting group and having a weight average molecular weight of 2,000 to 20,000.

As component (c-1), preferred are phenol derivatives containing 1 to 6, preferably 2 to 4, substituted or unsubstituted benzene rings.

Component (c-1) can be further divided into (i), (ii) and (iii) described below:

(i) Compounds prepared by dehydrohalogenation of a mixture of a phenolic compound such as bisphenol A or trisphenol and a tert-alkyl ester of a halogenated fatty acid such as tert-butyl bromoacetate in the presence of a base catalyst, by This replaces the hydrogen atom of the phenolic hydroxyl group by a tertiary alkoxycarbonylalkyl group. In those cases where the compound contains multiple hydroxyl groups, the other hydroxyl hydrogen atoms may also be replaced by other acid-cleavable, dissolution-inhibiting groups other than tertiary alkoxycarbonylalkyl groups.

(ii) Compounds prepared by substituting a carboxyl group containing compound such as biphenyl dicarboxylic acid, naphthalene dicarboxylic acid or benzophenone dicarboxylic acid with an acid-cleavable, dissolution inhibiting group.

or Hydroxyl substitution. In this case, the carboxyl and hydroxyl groups can be substituted with different acid-cleavable, dissolution-inhibiting groups.

Many of the phenolic compounds classified as (i) above have been known as phenolic compounds for photosensitive components in non-chemically amplified positive-tone resists, and for sensitive compounds added to such positive-tone resists. improving agent, and any of these known compounds may be used. Examples of these compounds include: bis(4-hydroxyphenyl)methane, bis(2,3,4-trihydroxyphenyl)methane, 2-(4-hydroxyphenyl)-2-(4'-hydroxyphenyl) ) propane, 2-(2,3,4-trihydroxyphenyl)-2-(2',3',4'-trihydroxyphenyl)propane, tris(4-hydroxyphenyl)methane, bis(4 -Hydroxy-3,5-dimethylphenyl)-2-hydroxyphenylmethane, bis(4-hydroxy-2,5-dimethylphenyl)-2-hydroxyphenylmethane, bis(4-hydroxy -3,5-dimethylphenyl)-3,4-dihydroxyphenylmethane, bis(4-hydroxy-2,5-dimethylphenyl)-3,4-dihydroxyphenylmethane, di (4-Hydroxy-3-methylphenyl)-3,4-dihydroxyphenylmethane, bis(3-cyclohexyl-4-hydroxy-6-methylphenyl)-4-hydroxyphenylmethane, di (3-cyclohexyl-4-hydroxyl-6-methylphenyl)-3,4-dihydroxyphenylmethane, 1-[1-(4-hydroxyphenyl)isopropyl]-4-[1, 1-Bis(4-hydroxyphenyl)ethyl]benzene, and dimers, trimers and tetramers of formaldehyde condensation products of phenols such as phenol, m-cresol, p-cresol and xylenol .

As the carboxyl group-containing compound of (ii) above, any known carboxylic acid compound can be used. Examples include cyclohexanecarboxylic acid, benzoic acid, salicylic acid, biphenyl polycarboxylic acid, naphthalene(di)carboxylic acid, naphthalenetriacetic acid, benzoylbenzoic acid, anthracenecarboxylic acid, benzophenonedicarboxylic acid, 1-naphthalene Glycolic acid and compounds represented by the formula:

As for the compound containing both carboxyl and hydroxyl groups in (iii) above, any known compounds can be used. Examples include 2,2'-bis(4-hydroxyphenyl)propanoic acid and 4,4'-bis(4-hydroxyphenyl)pentanoic acid.

Particularly preferred forms of compound (c-1) can be further classified into: (c-1-1) compounds represented by general formula (i) shown below, wherein at least one hydrogen atom of a hydroxyl or carboxyl group has been decomposed by an acid Dissociated, dissolution inhibiting group substitution, and condensation products of (c-1-2) formaldehyde with at least one compound selected from phenol, m-cresol, p-cresol and xylenol, wherein the hydroxyl At least one hydrogen atom has been replaced by tert-butoxycarboxyalkyl.

These compounds (c-1-1) and (c-1-2) provide a positive resist composition with high contrast, and can further improve resist pattern shape and resolution, and thus are preferable.

[Wherein, R ¹ to R ⁴ each independently represent a hydrogen atom, a linear, branched or cyclic alkyl group having no more than 6 carbon atoms, a lower alkoxy group, a hydroxyl group, a carboxyl group or an alkyl group containing a carboxyl group, although R ¹ to At least one of R ⁴ must be a hydroxyl or carboxyl group, each X independently represents a single bond, -C(O)- or -C(R ⁵ )(R ⁶ )-, R ⁵ represents a hydrogen atom or a lower alkyl group, R ⁶ represents a hydrogen atom, a lower alkyl group, a carboxyl group, an alkyl group containing a carboxyl group, or an aryl group represented by the general formula (ii) shown below (wherein, the groups ^R1 to ^R4 in the formula (ii) are as above defined), r represents 0 or an integer from 1 to 2, and q represents 0 or 1, although in those cases where q is 0, the groups enclosed in parentheses are hydrogen atoms]

In addition, compounds represented by the general formula (I) shown below, in which at least one hydrogen atom of a hydroxyl group or a carboxyl group has been replaced by an acid-dissociable, dissolution-inhibiting group, are particularly preferred:

[wherein, R ¹ to R ⁴ , and X are as defined above]

Examples of suitable straight-chain, branched-chain or cyclic alkyl groups of not more than ⁶ carbon atoms for the above groups R ^to R include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, cyclopentyl and cyclohexyl.

Examples of suitable lower alkoxy groups include alkoxy groups of 1 to 5 carbon atoms such as methoxy, ethoxy and propoxy.

Examples of suitable lower alkyl groups include alkyl groups of 1 to 5 carbon atoms such as methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl and tert-butyl. Suitable carboxy-containing alkyl groups include groups in which a carboxyl group is bonded to an alkylene group of 1 to 10 carbon atoms, and suitable examples of such an alkylene group include methylene, ethylene, and straight or branched chain propylene, butylene, hexylene, heptylene and nonylene.

Specific examples of component (c-1) according to the present invention include the compounds shown below:

Furthermore, among the above-mentioned (c-1-1) compounds, those represented by the formulas (1) and (2) shown below are preferable:

(where R' represents an acid-dissociable, dissolution-inhibiting group)

(where R' represents an acid-dissociable, dissolution-inhibiting group)

In the general formulas (1) and (2) shown above, examples of the R' group include the acid-cleavable, dissolution-inhibiting groups described above, and are preferably selected from tertiary alkoxycarbonyl, tertiary alkoxy at least one of carbonylalkyl, tertiary alkyl, cyclic ether, alkoxyalkyl and 1-alkylcycloalkyl.

Furthermore, it is preferred that the acid-cleavable, dissolution-inhibiting group is selected from the group consisting of tert-butoxycarbonyl, tert-butoxycarbonylmethyl, tert-butyl, tetrahydropyranyl, ethoxyethyl, 1-methyl at least one of cyclohexyl and 1-ethylcyclohexyl.

Furthermore, it is more preferred that the acid-cleavable, dissolution-inhibiting group is selected from the group consisting of tert-butoxycarbonylmethyl, tert-butyl, tetrahydropyranyl, ethoxyethyl, 1-methylcyclohexyl and 1- At least one group in ethylcyclohexyl.

Among these, tert-alkoxycarbonylmethyl is preferred, and among these, tert-butoxycarbonylmethyl is particularly desirable.

Among the compounds represented by the above-mentioned general formulas (1) and (2), those represented by the general formula (1) are preferred, and among these, it is particularly desirable that all R' groups are tert-butoxycarbonyl Methyl compounds.

The mixing ratio of component (C) is typically in the range of 0.1 to 20 parts by weight, preferably 0.5 to 10 parts by weight, per 100 parts by weight of component (A). By ensuring that the ratio is at least as large as the lower limit of the range, a reduction in the degree of development defects is obtained. Ensuring that the ratio does not exceed the upper limit is beneficial in terms of contrast.

In those cases where the low molecular weight component (c-1) is used, use of 0.5 to 10 parts by weight per 100 parts by weight of component (A) produces resist patterns with high resolution and excellent drying resistance, so is preferred.

A resist pattern can be formed using the positive resist composition of the present invention in the same manner as a conventional KrF positive resist composition.

The heating temperature used during prebake and post-exposure bake (PEB) is typically 90°C or higher, and in order to form a resist pattern with favorable rectangularity, the temperature is preferably 90 to 120°C, more preferably 90 to 110°C . Furthermore, the use of temperatures in this range means that the occurrence of microbridges can also be effectively suppressed.

According to Embodiment 1 of the positive resist composition of the present invention, a resist pattern having excellent resolution and favorable rectangularity can be obtained.

Furthermore, by using Embodiment 1 of the positive resist composition of the present invention, the occurrence of development defects such as microbridges can also be reduced.

Embodiment 2 of the positive resist composition of the present invention is capable of reducing the degree of development defects in the resist pattern while retaining excellent resolution. As a result, characteristics other than resolution such as the cross-sectional shape of the resist pattern can also be improved.

Furthermore, in the present invention, the protection ratio of hydroxyl groups in the copolymer (A1) is lower than that in conventional PHS resins, meaning that a satisfactory level of insolubility in alkali developing solutions can be obtained.

For example, the effects of improving resolution performance and improving squareness of the present invention can be confirmed by examining a resist pattern obtained after a development process using a SEM (Scanning Electron Microscope).

In addition, the effect of the present invention for suppressing development defects can be confirmed, for example, by inspecting a resist pattern using the above-mentioned SEM or development defect inspection apparatus, and looking for the presence of microbridges and other defects.

In addition, the positive resist composition of the present invention can also be desirably used in a method of forming a resist pattern that includes heat flow treatment described below and that produces a favorable flow rate. Specifically, the positive type resist composition of the present invention can be used to form an advantageous ultrafine resist pattern by a method of forming a resist pattern including heat flow treatment, even if the composition does not contain a crosslinking agent component ( component (E)), the crosslinking agent component may have a deteriorating effect on the storage stability of the resist composition. The reason for this finding is considered to be that heating actually causes a crosslinking reaction between the structural unit (a1) and the structural unit (a2) of the copolymer (A1). Component (E) may also be included, if desired.

In addition, as described above, the development step before the heat flow treatment can form a resist pattern showing a high level of resolution and rectangularity, and in which development defects have been prevented, meaning that the narrowed resist obtained by performing the subsequent heat flow treatment The patterns also exhibit high levels of resolution performance, excellent squareness and reduced levels of development defects.

"Method of Forming a Resist Pattern"

Next is a description of a method of forming a resist pattern according to the present invention.

First, the above-described positive resist composition of the present invention is applied onto the surface of a substrate such as a silicon wafer using a spin coater or the like, followed by prebaking. The coating of the positive resist composition is then selectively exposed with an exposure instrument through a desired mask pattern, followed by PEB (Post Exposure Baking). Next, a developing treatment using an alkali developing solution, followed by a rinsing treatment to wash away any developing solution left on the surface of the substrate, and those sections of the resist composition dissolved in the developing solution, followed by drying Substrate.

The steps up to this point can be performed using conventional techniques. Depending on the composition and characteristics of the positive resist composition to be used, operating conditions and the like can be appropriately set.

Exposure is preferably performed using a KrF excimer laser, although compositions of the invention may also be used with e-beam resists and EUV (extreme ultraviolet).

It is also possible to provide an organic or inorganic antireflection film between the substrate and the coating of the resist composition.

<Heat flow treatment>

In the method of forming a resist pattern according to the present invention, it is preferable to subject the resist pattern that has been formed by the above method to heat flow treatment, thereby narrowing the resist pattern. The following is a description of this heat flow treatment.

The heat flow treatment is performed by heating the resist pattern at least once. It is preferable to increase the number of repetitions of heating because it is possible to change the degree of change in resist pattern size per unit temperature (hereinafter referred to as flow rate). However, the number of steps increases, and the time required for processing increases, which leads to a decrease in throughput.

For the pattern size of the narrowed resist pattern formed on the wafer, the lower flow rate in the heat flow process produces higher in-plane uniformity, and the cross-sectional shape of the narrowed resist pattern is also excellent . If the resist film thickness is 1,000 nm or less, the film thickness has little influence on the flow rate.

The heating temperature used in the heat flow treatment is selected according to the composition of the resist pattern, and is typically selected in the range of 100 to 200°C, preferably 110 to 180°C. In those cases where two or more heating repetitions are performed, the second and subsequent heating repetitions are performed at the same temperature as the first heating repetition or at a higher temperature than the first heating repetition.

There is no particular limitation on the heating time, as long as it does not impede throughput and produce the desired resist pattern size, although each heating repetition is preferably performed for 30 to 270 seconds, more preferably 60 to 120 seconds.

The method of forming a resist pattern including heat flow treatment can be advantageously used in the formation of the type of ultra-fine resist hole pattern that is difficult to form using ordinary methods.

The method of forming a resist pattern according to the present invention is carried out using the positive resist composition of the present invention, therefore, for the composition not containing a crosslinking agent and the composition containing the above-mentioned crosslinking agent component (E) , a favorable flow rate can be obtained. Thus, a narrowed resist pattern can be obtained which exhibits high horizontal resolution and favorable rectangularity of the resist pattern, minimal development defects and a high level of in-plane uniformity of pattern dimensions.

Example

The following is a more detailed description of the invention using a series of examples.

Example 1

First, component (A) is prepared. That is, using a common method, in the presence of an acid catalyst, a copolymer (molar ratio: 80 : 20, weight average molecular weight (Mw): 8,000, polydispersity (Mw/Mn): 1.78) reacted with ethyl vinyl ether, thereby forming resin X (Mw=10,000, Mw/Mn=1.7), wherein A resin having protected some of the hydroxyl groups of the copolymer with 1-ethoxyethyl groups was used as component (A).

When this resin X was analyzed by ¹ H-NMR, the amount of 1-ethoxyethyl group was 18% with respect to all the hydroxyl groups in p-hydroxystyrene and adamantanol. This shows that the protection ratio of the hydroxyl group is 18 mol%.

In a mixed solvent of 500 parts by weight of PGMEA and EL (wherein the weight ratio of PGMEA:EL is 6:4), dissolve 100 parts by weight of component (A), 5.0 parts by weight of bis(cyclohexylsulfonyl)diazo Methane, 6.0 parts by weight of bis(isopropylsulfonyl)diazomethane and 2.0 parts by weight of triphenylsulfonium nonafluoromethanesulfonate as component (B) and 0.15 parts by weight of triethanolamine and 0.15 parts by weight of Triisopropylamine was used as component (D), whereby a positive resist composition was obtained.

Meanwhile, a substrate was prepared by laminating an organic antireflective film (trade name DUV-44, manufactured by Brewer Science Ltd.) on top of an 8-inch silicon wafer, and then heating at 205° C. to form a film with a thickness of 65 nm.

The positive type resist composition obtained above was applied to the surface of this substrate using a spinner, and then prebaked and dried on a 100° C. hot plate for 90 seconds, thereby forming a resist layer with a film thickness of 410 nm. .

Then, through a typical chromium reticle, using a KrF scanner (wavelength λ: 248nm) S203B (manufactured by Nikon Corporation, NA (numerical aperture) = 0.68, 2/3 ring illumination), a KrF excimer laser (248nm ) to selectively irradiate the layer, said chrome reticle is the mask used in reduced projection exposure.

Next, the irradiated resist was subjected to PEB treatment at 110° C. for 60 seconds, followed by puddle development in 2.38 wt % tetramethylammonium hydroxide aqueous solution at 23° C. Rinse with water for 15 seconds. Then, the resist was shake-dried, and then further dried by heating at 100° C. for 60 seconds, thereby forming a resist pattern.

In this way, a resist hole pattern with a hole diameter of 140 nm was formed. Furthermore, examination of the substrate and the resist pattern thus formed using a scanning electron microscope (Measurement SEM, S-9200) manufactured by Hitachi Ltd. revealed that the cross-sectional shape of the resist pattern was very favorable, being highly rectangular.

Furthermore, inspection of the substrate using a surface defect inspection instrument KLA2132 manufactured by KLA Tencor Corporation revealed only a very small amount of surface defects, the amount not exceeding 10, indicating effective suppression of developing defects.

Measurement of the pure water contact angle (fixed contact angle, which is also used below) of the unexposed portion showed a value of 59 degrees, indicating favorable hydrophilicity.

The depth of focus of the 140 nm resist hole pattern is 0.6 μm.

Furthermore, examination of a 1:1 line and space resist pattern formed in a similar manner revealed that excellent resolution was achieved even at a line width of 120 nm.

Example 2

In addition to using 4.0 parts by weight of bis(cyclohexylsulfonyl)diazomethane, 1.0 parts by weight of bis(2,4-dimethylphenylsulfonyl)diazomethane and 4.0 parts by weight of triphenylsulfonium nonafluorobutane Alkane sulfonate as component (B), using 0.3 parts by weight of triethanolamine and 0.3 parts by weight of triisopropanolamine as component (D), also adding 2 parts by weight represented by the formula (VI) shown below Except for the dissolution inhibitor, a positive resist composition was obtained in the same manner as in Example 1.

Meanwhile, an organic antireflective film (trade name DUV-44, manufactured by Brewer Science Ltd.) was laminated on top of an 8-inch silicon wafer, and then heated at 225° C. for 60 seconds to form a film with a thickness of 65 nm to prepare a substrate.

The positive resist composition obtained above was applied to the surface of this substrate using a spinner, and then prebaked and dried on a 100° C. hot plate for 60 seconds, thereby forming a resist layer with a film thickness of 287 nm. .

Then, through the 8% halftone reticle, using a KrF scanner (wavelength λ: 248 nm) NSR-S203B (manufactured by Nikon Corporation, NA (numerical aperture) = 0.68, 2/3 ambient illuminance), a KrF excimer laser (248 nm) selectively irradiates the layer.

Next, the irradiated resist was subjected to a post-exposure bake (PEB) treatment at 110° C. for 60 seconds, followed by a mud treatment in 2.38 wt % tetramethylammonium hydroxide aqueous solution at 23° C. Rinse with water for 15 seconds. Vibration drying, followed by further drying by heating at 100° C. for 60 seconds, thereby forming a resist pattern.

Confirmation of resist properties using a scanning electron microscope (measurement SEM, S-9200) manufactured by Hitachi Ltd. revealed that a line and space resist pattern with a pattern size of 120 nm has been formed, the pattern shape exhibits a high degree of rectangularity, and The depth of focus is 0.3 μm. In addition, the measurement of the development defect level showed that the result was 5 defects or less.

Reference example 1

Except for using 5.0 parts by weight of bis(cyclohexylsulfonyl)diazomethane as component (B), a positive resist composition was prepared in the same manner as in Example 2, and then this positive resist composition was used form a resist pattern.

As a result, a line-and-space pattern with a pattern size of 130 nm was formed, but the pattern had poor rectangularity in which the top of the pattern was rounded.

This reference example 1 corresponds to an example of the second aspect and is provided here for comparison with examples 1 and 2.

Reference example 2

Except using 5.0 parts by weight of triphenylsulfonium nonafluorobutanesulfonate as component (B), prepare a positive resist composition in the same manner as in Example 2, and then use this positive resist The composition forms a resist pattern.

As a result, a line-and-space pattern with a pattern size of 150 nm was formed, but the pattern was poor in rectangularity, in which a pattern having a T-top shape was formed.

This reference example 2 corresponds to an example of the second aspect and is provided here for comparison with examples 1 and 2.

Example 3

A positive resist composition was prepared in the same manner as in Example 1.

Using a spinner, on the surface of the same type of organic anti-reflective coating film substrate as used in Example 1, the same positive resist composition as used in Example 1 was applied, and then the composition was Prebaking and drying were performed on a 100° C. hot plate for 90 seconds, whereby a resist layer having a film thickness of 410 nm was formed.

Then, the layer was selectively irradiated with a KrF excimer laser (248 nm) through a 6% halftone reticle (hole pattern with a hole diameter of 150 nm), using the same KrF scanner as in Example 1.

Next, the irradiated resist was subjected to PEB treatment at 110° C. for 90 seconds, followed by sequential development, water rinsing, and drying in the same manner as in Example 1, thereby forming a resist pattern.

In this way, a resist hole pattern with a hole diameter of 150 nm was formed. Examination of the substrate on which the resist pattern had been formed in the same manner as in Example 1 revealed that the resist pattern shape had a high degree of rectangularity. In addition, surface defects are only a very small amount of not more than 10. In addition, the depth of focus of the resist hole pattern with a hole diameter of 150 nm was 0.6 μm.

Hole diameter measurements of the resist hole patterns were performed using a survey SEM.

Next, heat flow treatment is performed on the substrate on which the resist hole pattern has been formed by heating the substrate on a hot plate under predetermined conditions, thereby producing a narrowed resist hole pattern.

The flow rate was determined by changing the heating conditions used in the heat flow treatment while measuring the size of the resulting resist hole pattern, thereby determining the flow rate. In other words, in the same manner as above, five above-mentioned substrates were prepared, on which a pattern of resist holes with a diameter of 150 nm was formed, and these substrates were respectively heated at 140° C., 145° C., 150° C., Heat at 155°C and 160°C for 90 seconds.

At each temperature, the heating resulted in a narrowing of the hole diameter of the resist hole pattern, resulting in a favorable shape of the narrowed resist hole pattern, although the narrowed hole diameter varied depending on the heating temperature used. A graph was drawn so as to show the temperature along the horizontal axis and the degree of change in the size of the resist pattern (change in hole diameter) at each temperature along the vertical axis, and the resist pattern after narrowing was determined using the graph At a point where the size (pore diameter) is 100 nm, the size of the resist pattern changes per unit temperature change (° C.), that is, the flow rate.

The resist pattern size (pore diameter) after narrowing was: 147 nm at 140°C, 140 nm at 145°C, 128 nm at 150°C, 100 nm at 155°C, and 80 nm at 160°C for a narrowed hole of 100 nm The required flow rate for the diameter is 4.8 nm/°C.

From these results, it is apparent that Examples 1 to 3 using the positive resist composition according to the first aspect of the present invention produced resist patterns having excellent resolution and favorable rectangularity.

Furthermore, in Example 3, in the case of using the positive resist composition of the present invention in the method of forming a resist pattern including heat flow treatment, a favorable flow rate was obtained.

Example 4

First, component (A) is prepared. That is, using a common method, in the presence of an acid catalyst, a copolymer (molar ratio: 80 : 20, weight-average molecular weight (Mw): 8,000, polydispersity (Mw/Mn): 1.78) was reacted with ethyl vinyl ether, thereby forming resin X (Mw=10,000, Mw/Mn=about 1.7), This resin, in which some hydroxyl groups of the copolymer have been protected by 1-ethoxyethyl groups, was used as component (A).

When this resin X was analyzed by ¹ H-NMR, the amount of 1-ethoxyethyl group was 20% relative to the total hydroxyl groups in p-hydroxystyrene and adamantanol. This indicates that the protection ratio of the hydroxyl group is 20 mol%.

In a mixed solvent of 500 parts by weight of PGMEA and EL (wherein the weight ratio of PGMEA:EL is 6:4), dissolve 100 parts by weight of component (A), 4.0 parts by weight of bis(cyclohexylsulfonyl)diazo Methane, 1.0 parts by weight of bis(2,4-dimethylphenylsulfonyl)diazomethane and 4.0 parts by weight of triphenylsulfonium nonafluoromethanesulfonate as component (B) and 2 parts by weight from the following The component (°C) represented by the shown chemical formula, the triethanolamine of 0.3 parts by weight and the triisopropylamine of 0.3 parts by weight are used as component (D), thus obtaining the positive resist composition:

Meanwhile, the substrate was prepared by coating an organic antireflection film (trade name DUV-44, manufactured by Brewer Science Ltd.) on top of an 8-inch silicon wafer, and then heating at 225° C. for 60 seconds, thereby forming its A substrate with an anti-reflection film with a film thickness of 65 nm formed on it.

Using a spin coater, the above-obtained positive resist composition was applied to the surface of the antireflective film on the top of this substrate, and then prebaked and dried on a 100° C. electric hot plate for 60 seconds, thereby forming a film having a thickness of 287nm resist layer.

Then, through an 8% halftone reticle, using a KrF scanner (wavelength λ: 248 nm) NSR-S203B (manufactured by Nikon Corporation, NA (numerical aperture) = 0.68, 2/3 ring illumination), the KrF excimer A laser (248 nm) selectively irradiates the resist layer.

Next, the obtained resist layer was subjected to PEB treatment at 110° C. for 60 seconds, then subjected to mud treatment at 23° C. for 60 seconds in a 2.38% by weight aqueous solution of tetramethylammonium hydroxide, and rinsed with pure water for 15 seconds. Second. The resist was then shake-dried, and then further dried by heating at 100° C. for 60 seconds, thereby forming a resist pattern.

Examination of the substrate and the resist pattern thus formed using a scanning electron microscope (Measuring SEM, S-9200) manufactured by Hitachi Ltd. revealed that a line and space resist pattern of 120 nm was resolved. In addition, there were no development defects such as development residue.

Reference example 3

When the test was carried out in the same manner as in Example 4, except that component (C) was not added, and the resulting pattern was evaluated, a 130 nm line and space resist pattern was resolved. However, there are development residues in the resist pattern in which there are obvious fine uneven development defects, especially at the interface between lines and spaces.

This reference example 3 corresponds to an example of the first aspect, and is provided here for comparison with example 4.

From the results of Example 4 and Reference Example 3 described above, it is clear that by adding component (C), occurrence of development defects such as development residue can be effectively suppressed.

Claims (11)

1. A positive resist composition comprising a resin component (A) containing an acid-dissociable, dissolution-inhibiting group and showing improved alkali solubility under the action of an acid and an acid-generating Agent component (B), wherein The resin component (A) is a copolymer ( A1), wherein the hydroxyl group of the structural unit (a1) and the alcoholic hydroxyl group of the structural unit (a2) are protected by an acid-dissociable, dissolution-inhibiting group in a protection ratio of at least 10 mol% to no more than 25 mol % range; The acid generator component (B) includes a diazomethane acid generator and an onium salt-based acid generator, and Said composition also comprises component (C) which contains at least one acid-dissociable, dissolution-inhibiting group and its , the dissolution inhibiting group dissociates to generate an organic carboxylic acid, For every 100 parts by weight of component (A), the mixing ratio of said component (C) is in the range of 0.1 to 20 parts by weight, The component (C) is a phenol derivative containing 1 to 6 substituted or unsubstituted benzene rings, has a weight average molecular weight in the range of 200 to 1,000, and is represented by the general formula (1) shown below Compound:

wherein R' represents an acid-dissociable, dissolution-inhibiting group. 2. The positive resist composition according to claim 1, wherein in said general formula (1), R' represents t-butoxycarbonylmethyl. 3. The positive resist composition according to claim 1, wherein said copolymer (A1) has a weight average molecular weight of at least 2,000, but not more than 8,500. 4. The positive resist composition according to claim 1, wherein, in said copolymer (A1), said structural unit ( The molar ratio between a1) and the structural unit (a2) is 85:15 to 70:30. 5. The positive resist composition according to claim 1, wherein said structural unit (a2) is a structural unit derived from (meth)acrylate containing an aliphatic polycyclic group having an alcoholic hydroxyl group . 6. The positive resist composition according to claim 5, wherein said structural unit (a2) is a structural unit derived from (meth)acrylate containing an adamantyl group having an alcoholic hydroxyl group. 7. The positive resist composition according to claim 1, wherein the acid-dissociable, dissolution-inhibiting group is a 1-lower alkoxyalkyl group. 8. The positive resist composition according to claim 1, wherein said copolymer (A1) has a polydispersity Mw/Mn ratio of No more than 2.0. 9. The positive resist composition according to claim 1, further comprising a nitrogen-containing organic compound (D). 10. A method for forming a resist pattern, the method comprising the steps of: using the positive resist composition according to claim 1 to form a positive resist film on top of a substrate, for said positive resist The resist film is selectively exposed and developed to form the resist pattern. 11. The method of forming a resist pattern according to claim 10, wherein said resist pattern formed by performing a development treatment is subjected to heat flow treatment, thereby narrowing said resist pattern.