JP2003084431A - Method for adjusting surface energy of antireflection film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antireflection film for lithography having a high antireflection effect, free of intermixing with a photoresist layer, giving an excellent photoresist pattern, having a higher dry etching rate than the photoresist and ensuring a larger margin for the depth of a focus and higher resolution than a conventional antireflection film. SOLUTION: In a method for forming an antireflection film as a layer under a photoresist using an antireflection film forming material comprising a resin, a crosslinker and a solvent, an antireflection film whose surface energy has been adjusted according to the magnitude of the surface energy of the coating photoresist is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for an antireflection film material which is effective in reducing the adverse effect of reflection from a base substrate, and a method for forming a photoresist pattern using the composition for an antireflection film material. is there.

[0002]

2. Description of the Related Art Conventionally, in the manufacture of semiconductor devices, fine processing by lithography using a photoresist composition has been performed. The fine processing forms a thin film of a photoresist composition on a silicon wafer, irradiates with active rays such as ultraviolet rays through a mask pattern on which a semiconductor device pattern is drawn, and develops it.
This is a processing method of etching a silicon wafer using the obtained photoresist pattern as a protective film. However, in recent years, as the degree of integration of semiconductor devices has increased, the wavelength of active rays used has tended to be shortened from the KrF excimer laser (248 nm) to the ArF excimer laser (193 nm). Along with this, the influences of diffuse reflection of active rays from the substrate and standing waves are major problems. Therefore, an antireflection film (Bottom An) is formed between the photoresist and the substrate.
ti-Reflective Coating, BAR
The method of providing C) has been widely studied.

Known antireflection films are inorganic antireflection films such as titanium, titanium dioxide, titanium nitride, chromium oxide, carbon and α-silicon, and organic antireflection films made of a light absorbing substance and a polymer compound. ing. While the former requires equipment such as a vacuum vapor deposition apparatus, a CVD apparatus, and a sputtering apparatus for forming a film, the latter is advantageous because it requires no special equipment, and many studies have been conducted. For example, an acrylic resin-type antireflection film having a hydroxyl group and a light-absorbing group which are cross-linking reactions described in US Pat. No. 5,919,599 in the same molecule, US Pat. No. 5,693,691.
Novolak resin-type antireflection films having a hydroxyl group and a light-absorbing group in the same molecule, which are cross-linking reactions described in the specification of the publication, and the like.

Physical properties desired as a material for an organic antireflection film are that it has a large absorbance for light and radiation and that it does not intermix with a photoresist layer (it is insoluble in a photoresist solvent). ,
No low-molecular diffuses from the antireflective coating material into the overcoat photoresist during coating or heat drying, having a higher dry etching rate than photoresist, less defects after coating, exposure and development That is, the photoresist pattern is fine, and the pattern does not collapse even if the focus shifts during exposure (a wide focus margin). SPIE, Vol. 2195
225-229 (1999) and Proc. SPIE,
Vol. 2195, 225-229 (1994).

[0005]

The focus margin is the width of the entire depth region in which the photoresist pattern can be maintained in a practical state when the focus shifts upward or downward with respect to the optimum focus position. If the width is wide, it means that there is a large margin in the manufacturing process. For example, one of techniques for extending the focus margin is described in Japanese Patent Laid-Open No. 6-348036.

Manufacturing of semiconductor devices includes a step of forming a photoresist pattern by selectively exposing a photoresist film formed on a workpiece such as a silicon wafer and then developing it. ing. During this exposure, the focus of the exposure irradiation light may deviate from the optimum position. From the side of the manufacturing equipment, this factor is field curvature, focus position reproducibility (detection, stage), focus control stability (heat, environment).
From the side surface of the wafer, there are device steps formed on the wafer, global inclination of the wafer, local unevenness, and the like. Then, due to the deviation of the focus from the optimum position, the shape of the photoresist pattern is changed such as thinning of the pattern, which causes defective formation of the photoresist pattern such as pattern collapse, and the photoresist pattern is formed with high dimensional accuracy. The problem arises that you cannot do it. In particular, in fine processing using irradiation light with a wavelength of 193 nm, thinning of the photoresist pattern and pattern collapse due to deviation from the optimum focus position pose problems. In such a situation, it is possible to reduce the influence of the shift of the focus of the exposure irradiation light on the formation of the photoresist pattern, that is,
There is an increasing demand for antireflection film materials to have a wide focus depth margin. In addition, as the degree of integration of semiconductor devices increases, the antireflective film material is required to have a property of having higher resolution, that is, capable of forming a rectangular photoresist pattern having a finer pattern size. Is becoming.

For example, the pattern collapse problem has been attracting attention due to the miniaturization of photoresist patterns. The photoresist pattern collapse often occurs due to the miniaturization of the line width of the photoresist and the shift of the focus from the optimum position, which causes transfer failure to the underlying substrate. In addition, the coating property of the antireflection film on the base substrate is improved, the coating property of the photoresist formed on the antireflection film is improved, and the defects generated in the pattern forming process, so-called defects are improved. It is desired to be done. For that purpose, it is considered effective to modify the surface condition of the coating film.

[0008]

The present invention is to adjust the surface energy of an antireflection film as a guide for surface modification. That is, as a first aspect of the present invention, a resin,
In the method of forming an antireflection film in the lower layer of the photoresist using an antireflection film forming material containing a crosslinking agent and a solvent, the surface energy of the antireflection film, depending on the magnitude of the surface energy of the coated photoresist. A method of forming an antireflection film, which comprises forming an adjusted antireflection film. As a second aspect, the resin is a copolymer of monomers constituting the resin so that the surface energy of the antireflection film is adjusted. A method for forming an antireflection film according to the first aspect, which comprises a copolymer resin having an adjusted ratio,
As a third aspect, the method for forming an antireflection film according to the first aspect or the second aspect, wherein the resin contains a structure of a repeating unit (A) having at least an absorptive group, and as a fourth aspect, in the resin. The light-absorptive group contained in the repeating unit (A) is selected from the group consisting of an anthryl group, a naphthyl group, and a phenyl group. 1st viewpoint to 4th viewpoint which contains the structure of the repeating unit (A) which has a hydrophilic group, the structure of the repeating unit (B) which has a hydrophilic group, and the structure of the repeating unit (C) which has a hydrophobic group. As a sixth aspect, the forming method according to any one of
The resin is an acrylic resin, and 1000 to 10
And a repeating unit (A) of 1 to 98% by weight, a repeating unit (B) of 1 to 98% by weight, and a repeating unit (C) of 1 to 98. % By weight, and the repeating unit (A),
The total amount of (B) and (C) does not exceed 100% by weight, the method for forming an antireflection film according to any one of the first to fifth aspects, and the seventh aspect, the repeating unit in the resin. The hydrophilic group contained in (B) is selected from the group consisting of a hydroxyl group, an amino group, an isocyanate group, an amide group, a carboxyl group, a mercapto group, a methylol group, an acyloxyalkyl group, and a sulfonic acid group. The method for forming an antireflection film according to any one of 1st to 6th viewpoints, and 8th viewpoint includes the repeating unit (C) in the resin.
The hydrophobic group contained in is optionally substituted with 1 carbon atoms
To linear and branched alkyl groups having 20 to 20 carbon atoms, optionally substituted aromatic ring groups having 4 to 14 carbon atoms, alicyclic groups, heteroaromatic ring groups and heterocyclic groups, having 1 to 20 carbon atoms As a ninth aspect, the method for forming an antireflection film according to any one of the first aspect to the seventh aspect, which is selected from the group consisting of an alkoxy group and a halogenated alkyl group having 1 to 20 carbon atoms, 9. The method for forming an antireflection film according to any one of the first to eighth aspects, wherein the magnitude of the surface energy of the antireflection film is adjusted to match the magnitude of the surface energy of the photoresist. As a tenth aspect, the method according to any one of the first to eighth aspects in manufacturing a semiconductor device using a lithographic process of forming an antireflection film on a substrate, coating a photoresist, and then performing exposure and development. By using the antireflection film formed by the method, the surface energy of the antireflection film is adjusted so as to match the magnitude of the surface energy of the overcoat photoresist at the interface between the photoresist and the antireflection film. And a method for manufacturing a semiconductor device.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is characterized in that the surface energy of an antireflection film is adjusted according to the magnitude of the surface energy of a coated photoresist to form an antireflection film. It is a forming method. Here, the method of calculating the surface energy value is shown below, but the method of calculating the surface energy value in the present invention is not limited to this. The following equation (I) is derived using Owen's approximate equation.

[Equation 1] From this equation, using water and methylene iodide droplets with known surface energy dispersion force component γ ^d and polar force component γ ^p , the contact angle was measured on the solid surface, and γ _S ^d and γ _{S of the} solid surface were measured. It is calculated by solving the simultaneous equations of ^p . The surface energy values of methylene iodide and water used in the present invention are shown in Table 1 (unit is mN / m).

[Table 1] Let θ be the contact angle of methylene iodide and θ ′ be the contact angle of water,
Substituting into the above equation, the following equation (II):

[Equation 2] And formula (III):

[Equation 3] Is obtained. Using this formula, γ _S ^d and γ _S ^p of the antireflection film and the photoresist were calculated. The surface energy γ _S is calculated by the sum of these, that is, γ _S = γ _S ^d + γ _S ^p . The surface is modified by adjusting these surface energies.

In the present invention, the adjustment of the surface energy is achieved by a method of using a copolymer resin in which the copolymerization ratio of the monomers constituting the resin is changed in the antireflection film forming material containing the resin, the crosslinking agent and the solvent. It An acrylic resin can be used as the resin, and the weight average molecular weight is 1000 to 1,000,000. The repeating unit (A) in the resin is 1 to 98% by weight, the repeating unit (B) is 1 to 98% by weight, and the repeating unit (C) is 1%.
It can be copolymerized at a ratio of up to 98% by weight.

The above-mentioned copolymer resin contains at least the structure of the repeating unit (A) having an absorptive group. The light-absorbing group contained in the repeating unit (A) in this resin is selected from the group consisting of an anthryl group, a naphthyl group, and a phenyl group. Examples of the raw material for the structure of the repeating unit (A) having a light absorbing group include acrylic acid ester and methacrylic acid ester having units such as anthryl group, naphthyl group and phenyl group, and benzyl (meth) acrylate and methoxy. Examples thereof include benzyl (meth) acrylate, phenyl (meth) acrylate, hydroxyphenyl (meth) acrylate, cresyl (meth) acrylate, naphthyl (meth) acrylate, and anthryl (meth) acrylate.

The above-mentioned copolymer resin is composed of the structure of the repeating unit (A) having a light-absorbing group and other structural parts, and by changing the copolymerization ratio thereof, the copolymer resin, the cross-linking agent and the solvent. It is possible to apply a desired surface energy to the antireflection film by applying the antireflection film-forming material consisting of the above onto the substrate, drying and baking. The copolymer resin contains a structure of a repeating unit (A) having a light-absorbing group, a structure of a repeating unit (B) having a hydrophilic group, and a structure of a repeating unit (C) having a hydrophobic group. Is preferred. The above-mentioned light-absorbing group, hydrophilic group and hydrophobic group can be incorporated into the main chain forming the skeleton of the resin itself, but the light-absorbing group, hydrophilic group from the main chain forming the skeleton of the resin It can have a structure in which a group and a hydrophobic group are suspended.

The hydrophilic group contained in the repeating unit (B) in the above resin is, for example, a hydroxyl group, amino group, isocyanate group, amide group, carboxyl group, mercapto group, methylol group, acyloxyalkyl group or sulfonic acid group. Can be mentioned. Examples of the raw material for the structural unit of the repeating unit (B) having a hydrophilic group include acrylic acid esters and methacrylic acid esters having an alkyl group having 1 to 100 carbon atoms substituted with the above functional group, and examples thereof include 2-hydroxyethyl. Hydroxyalkyl (such as (meth) acrylate, 2-hydroxypropyl (meth) acrylate, ethylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, propylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate ( Aminoalkyl methacrylates such as (meth) acrylate, aminopropyl (meth) acrylate, aminoethyl (meth) acrylate,
(Meth) acrylic acid and the like can be mentioned.

The above-mentioned resin preferably has a functional group capable of forming a cross-link with a cross-linking agent in its structure. A part of the hydrophilic group contained in the repeating unit (B) in the resin has a role of a crosslink bond-forming group with the crosslinking agent at the same time as the hydrophilic group. Particularly, a hydroxyl group can be preferably used, and in the structure of the repeating unit (B) having hydrophilicity, when a hydroxyl group is used as a hydrophilic group, the hydroxyl group serves as a hydrophilic group and at the same time partially crosslinks with a crosslinking agent. The formation of bonds is possible.

The hydrophobic group contained in the repeating unit (C) in the above resin has a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, and a substituent. Also selected from the group consisting of an aromatic ring group having 4 to 14 carbon atoms, an alicyclic group, a heteroaromatic ring group and a heterocyclic group, an alkoxy group having 1 to 20 carbon atoms, and a halogenated alkyl group having 1 to 20 carbon atoms. What is mentioned can be used preferably. The starting material for the structural unit of the repeating unit (C) having a hydrophobic group is, for example, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, butyl methacrylate, t-
Alkyl (meth) acrylates such as butyl methacrylate, 2-methylpropyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate,
Epoxyalkyl (meth) acrylates such as 2,3-epoxypropyl methacrylate, heteroaromatic ring group-containing (meth) acrylates such as furfuryl methacrylate, heterocyclic group-containing (meth) acrylates such as butyl lactone methacrylate, benzyl (meth) acrylate , Methoxybenzyl (meth) acrylate, phenyl (meth) acrylate, hydroxyphenyl (meth) acrylate, cresyl (meth) acrylate, naphthyl (meth) acrylate, anthryl (meth) acrylate and other aromatic ring group-containing (meth) acrylate, cyclohexyl Aliphatic group-containing (meth) acrylates such as (meth) acrylate and adamantyl (meth) acrylate, 2,2,2
-A halogenated alkyl group-containing (meth) acrylic acid ester such as trifluoroethyl methacrylate, 2,2,2-trichloroethyl methacrylate, an alkoxy group-containing (meth) acrylate such as 2-ethoxyethyl methacrylate, diethylene glycol monomethyl ether methacrylate, Can be mentioned.

It is desired that these repeating units (C) impart hydrophobicity to the copolymer and do not lead to a decrease in dry etching rate when used as an antireflection film. From these, the hydrophobic group contained in the repeating unit (C) is particularly preferably an alkyl group, an alkoxy group, or a heterocycle among the above.

The present invention uses a lithographic process in which an antireflection film-forming material containing a resin, a crosslinking agent and a solvent is used to form an antireflection film on a substrate, a photoresist is coated on the antireflection film, and exposure and development are performed. In the manufacturing of a semiconductor device, the surface energy of the antireflection film is adjusted according to the magnitude of the surface energy of the photoresist to be coated.

The method of forming an antireflection film of the present invention is achieved by using a copolymer resin as the resin in the antireflection film forming material and using a copolymer in which the copolymerization ratio of the copolymer resin is changed. Therefore, the surface energy of the photoresist to be used can be measured, and the copolymerization ratio can be changed according to the measured value, whereby the adjustment can be performed by a simple method.

The copolymer resin has a repeating unit (A) structure having a light-absorbing group, a repeating unit (B) structure having a hydrophilic group, and a repeating unit (C) structure having a hydrophobic group. It is preferable that they are contained, and the copolymerization ratio of (A), (B) and (C) can be changed according to the magnitude of the surface energy of the overcoat photoresist.

The copolymer can change the surface energy by essentially changing the ratio of the hydrophilic component and the hydrophobic component. Repeating unit (A) having a light-absorbing group
The structure of can basically be a hydrophobic group, but this light-absorbing group is an anthryl group, as illustrated.
Those having an aromatic ring such as a naphthyl group and a phenyl group are mainly used, and if the introduction amount of these aromatic rings is large, the dry etching rate of the antireflection film is lowered in the dry etching step, which is not preferable. That is, when the formed resist pattern is dry-etched, the dry etching rate of the underlying antireflection film is not sufficiently higher than the dry etching rate of the resist, so the antireflection film is removed by dry etching. Then the resist is also removed while exposing the base,
It is considered difficult to transfer an accurate resist pattern to the substrate. Therefore, it is necessary to suppress the introduction amount of the structure (A) in the copolymer, and therefore it is necessary to appropriately introduce the structure (C) as a hydrophobizing component.

In the present invention, it has been found that the surface energy of the antireflection film can be changed according to the surface energy of the photoresist coated on the upper layer. When the method of the present invention is used, the surface energy at the interface between the antireflection film and the photoresist film existing thereabove is the same, or the value of the surface energy of the antireflection film is the value of the surface energy of the photoresist film. It was found that a wide focus depth margin and high resolution can be obtained at the time of exposure by approaching to. by this,
It is possible to form a photoresist pattern having a finer pattern size, and it is possible to manufacture a highly integrated semiconductor device. In this case, it is necessary to match the surface energy at the interface between the antireflection film and the photoresist film existing thereabove, or to bring the surface energy value of the antireflection film close to the surface energy value of the photoresist film. However, for the antireflection film and the photoresist film, the surface energy value based on the contact angle between them should be the same as the surface energy value of the photoresist film within a range of ± 2 mN / m. Is preferred. As a result, a high focus depth margin can be obtained, and exposure with a wide margin can be performed even when the focus shifts during exposure, the focusing operation is easy, and the photoresist pattern can be formed with high dimensional accuracy. It becomes possible and is useful in manufacturing a semiconductor device. When the surface energy value of the antireflection film is within ± 2 mN / m with respect to the surface energy value of the photoresist film, the width of the focus depth margin is 0.8 μm or more.

Even if the surface energy difference exceeds the range of ± 2 mN / m, the width of the focus depth margin is reduced, but the photoresist pattern can be formed by accurately performing the focusing operation in the narrow focus range. .

The molecular weight of the resin forming the antireflection film of the present invention varies depending on the coating solvent used, the solution viscosity, the film shape, etc., but the weight average molecular weight is 1000 to 1000.
It is 000. The solid content of the antireflection film-forming composition of the present invention is 0.1 to 50% by weight. The content of the resin is 0.1 to 100 parts by weight of the total composition.
It is 50 parts by weight, preferably 1 to 30 parts by weight.

The resin used in the present invention may be a random copolymer, a block copolymer or a graft copolymer. The resin forming the antireflection film of the present invention can be synthesized by a method such as radical polymerization, anionic polymerization, or cationic polymerization. As for the form, various methods such as solution polymerization, suspension polymerization, emulsion polymerization, and bulk polymerization are possible.

The antireflection film-forming composition of the present invention may contain a crosslinking agent having at least two crosslinking functional groups. Examples of the cross-linking agent include melamine-based, substituted urea-based, and epoxy group-containing polymer-based agents.
Compounds such as methoxymethylated glycouril or methoxymethylated melamine are preferable, and tetramethoxymethylglycoluril or hexamethoxymethylol melamine is particularly preferable. The amount of the crosslinking agent added varies depending on the coating solvent used, the underlying substrate used, the required solution viscosity, the required film shape, etc., but 0.001 to 20 parts by weight relative to 100 parts by weight of the total composition. , Preferably 0.01 to 10 parts by weight, more preferably 0.1 to 5.0 parts by weight.

The antireflection film-forming composition of the present invention may further contain a light absorber, a rheology control agent, and
Adhesion aids, surfactants and the like can be added.

The rheology control agent mainly improves the fluidity of the antireflection film-forming composition, especially in the baking step.
It is added for the purpose of enhancing the filling property of the antireflection film-forming composition inside the hole. Specific examples include phthalic acid derivatives such as dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dihexyl phthalate and butyl isodecyl phthalate, dinormal butyl adipate,
Diisobutyl adipate, diisooctyl adipate,
Adipic acid derivatives such as octyldecyl adipate, maleic acid derivatives such as dinormal butyl maleate, diethyl maleate and dinonyl maleate, oleic acid derivatives such as methyl oleate, butyl oleate and tetrahydrofurfuryl oleate, or normal butyl stearate, glyceryl stearate. Examples thereof include stearic acid derivatives such as rate. These rheology control agents are usually added in a proportion of less than 30 parts by weight based on 100 parts by weight of the total composition of the antireflection film for lithography.

The adhesion aid is added mainly for the purpose of improving the adhesion between the substrate or the photoresist and the composition for forming an antireflection film, and especially for preventing the photoresist from peeling during development. Specific examples include trimethylsilane, dimethylvinylchlorosilane, methyldiphenylchlorosilane, chlorosilanes such as chloromethyldimethylchlorosilane, trimethylmethoxysilane,
Dimethyldiethoxysilane, methyldimethoxysilane,
Alkoxysilanes such as dimethylvinylethoxysilane, diphenyldimethoxysilane, phenyltriethoxysilane, hexamethyldisilazane, silazanes such as N, N′-bis (trimethylsiline) urea, dimethyltrimethylsilylamine and trimethylsilylimidazole,
Vinyltrichlorosilane, γ-chloropropyltrimethoxysilane, γ-aminopropyltriethoxysilane,
Silanes such as γ-glycidoxypropyltrimethoxysilane, benzotriazole, benzimidazole, indazole, imidazole, 2-mercaptobenzimidazole, 2-mercaptobenzthiazole, 2-mercaptobenzoxazole, urazolethiouracil, mercaptoimidazole, Examples thereof include heterocyclic compounds such as mercaptopyrimidine, urea such as 1,1-dimethylurea and 1,3-dimethylurea, and thiourea compounds. These adhesion auxiliaries are usually added in an amount of less than 5 parts by weight, preferably less than 2 parts by weight, based on 100 parts by weight of the total composition of the antireflection film for lithography.

A surfactant can be added to the antireflection film-forming composition of the present invention in order to further improve coatability against surface unevenness without causing pinholes or installation. Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether and other polyoxyethylene alkyl ethers, polyoxyethylene octylphenol ether, polyoxyethylene nonylphenol ether. Polyoxyethylene alkyl allyl ethers, polyoxyethylene / polyoxypropylene block copolymers, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, sorbitan tristearate, etc. Sorbitan fatty acid esters, polyoxyethylene sorbitan monolaurate, polyoxyethylene sol Monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate,
Nonionic surfactants such as polyoxyethylene sorbitan tristearate and other polyoxyethylene sorbitan fatty acid esters, eftop EF301, EF30
3, EF352 (manufactured by Tochem Products Co., Ltd.), Megafask F171, F173 (Dainippon Ink Co., Ltd.)
Manufactured by Sumitomo 3M Limited, Asahi Guard AG710, Surflon S-382, SC101, SC102, SC103, S
C104, SC105, SC106 (manufactured by Asahi Glass Co., Ltd.)
Fluorine-based surfactants such as Organosiloxane Polymer KP341 (produced by Shin-Etsu Chemical Co., Ltd.) and the like. The content of these surfactants is usually 0.2 parts by weight or less, preferably 0.1 parts by weight or less, per 100 parts by weight of the total composition of the present invention. These surfactants may be added alone or in combination of two or more.

In the present invention, as the solvent for dissolving the above resin, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol, propylene glycol monomethyl are used. Ether, propylene glycol monomethyl ether acetate, propylene glycol propyl ether acetate, toluene, xylene, methyl ethyl ketone, cyclopentanone, cyclohexanone, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, hydroxyacetic acid Ethyl, methyl 2-hydroxy-3-methylbutanoate Methyl 3-methoxypropionate,
Ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethyl acetate, butyl acetate, ethyl lactate, butyl lactate, cyclohexanone and the like can be used. These organic solvents may be used alone or in combination of two or more.

Further, a high boiling point solvent such as propylene glycol monobutyl ether or propylene glycol monobutyl ether acetate can be mixed and used. Among these solvents, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, butyl lactate, and cyclohexanone are preferable for improving the leveling property.

As the photoresist applied to the upper layer of the antireflection film of the present invention, either a negative type or a positive type can be used. A positive type photoresist containing a novolac resin and 1,2-naphthoquinonediazide sulfonic acid ester is used. A chemically amplified photoresist consisting of an acid generator and a binder having a group that decomposes by acid to increase the alkali dissolution rate, and decomposes by an alkali-soluble binder, a photoacid generator and acid to increase the alkali dissolution rate of the photoresist Chemically amplified photoresists consisting of low molecular weight compounds, photo-acid generators and binders having groups that decompose by acid to increase alkali dissolution rate and low molecular weight compounds that decompose by acid to increase alkali dissolution rate of photoresist There is a chemically amplified photoresist.

As a developer for a positive photoresist having an antireflection film for lithography formed using the antireflection film-forming composition of the present invention, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, Inorganic alkalis such as sodium metasilicate and aqueous ammonia, primary amines such as ethylamine and n-propylamine, secondary amines such as diethylamine and di-n-putylamine, tertiary amines such as triethylamine and methyldiethylamine, Uses an aqueous solution of alcohol amines such as dimethylethanolamine and triethanolamine, quaternary ammonium salts such as tetramethylammonium hydroxide, tetraethylammonium hydroxide and choline, and cyclic amines such as pyrrole and piperidine, etc. To do Kill. Furthermore, alcohols such as isopropyl alcohol in the aqueous solution of the alkalis,
It is also possible to use a nonionic surfactant or the like in an appropriate amount. Of these, preferred developers are quaternary ammonium salts, more preferably tetramethylammonium hydroxide and choline.

Next, the photoresist pattern forming method of the present invention will be described. A spinner, a spinner, and the like are formed on a substrate (eg, a silicon / silicon dioxide coating, a glass substrate, a transparent substrate such as an ITO substrate) used for manufacturing precision integrated circuit devices.
The antireflection film-forming composition is applied by an appropriate application method such as a coater, and then baked and cured to form an antireflection film. Here, the thickness of the antireflection film is 0.01 to 3.
0 μm is preferable. The conditions for baking after coating are 80 to 250 ° C. and 1 to 120 minutes. Then, a good photoresist can be obtained by applying a photoresist, exposing through a predetermined mask, developing, rinsing and drying. Post-exposure heating (PE
B: Post Exposure Bake) can also be performed.

[0035]

EXAMPLES Synthesis Example 1 5.44 g of benzyl methacrylate corresponding to the raw material of the repeating unit (A), 8.00 g of 2-hydroxypropyl methacrylate corresponding to the raw material of the repeating unit (B),
And methyl methacrylate represented by the formula (1) corresponding to the raw material of the repeating unit (C):

[Chemical 1] After dissolving 2.56 g in 64 g of propylene glycol monomethyl ether, the reaction solution was heated to 70 ° C., and at the same time, nitrogen was flown into the reaction solution. Then, as a polymerization initiator, azobisisobutyronitrile AIBN (Junsei Kagaku Co., Ltd.)
0.16 g of product) was added. After stirring under a nitrogen atmosphere for 24 hours, 0.05 g of 4-methoxyphenol (product of Tokyo Kasei Co., Ltd.) was added as a polymerization terminator. GPC analysis of the obtained resin revealed that the weight average molecular weight thereof was 84,200 in terms of standard polystyrene. The solid content in the solution was 20% by weight.

Synthesis Example 2 Instead of methyl methacrylate corresponding to the raw material of the repeating unit (C), ethyl methacrylate represented by the formula (2):

[Chemical 2] The same procedure as in Synthesis Example 1 was performed except that 2.56 g was used. When the GPC analysis of the obtained resin was performed, the weight average molecular weight was 73400 in terms of standard polystyrene. The solid content in the solution was 20% by weight.

Synthesis Example 3 2,3-epoxypropyl methacrylate represented by the formula (3) instead of methyl methacrylate corresponding to the raw material of the repeating unit (C):

[Chemical 3] The same procedure as in Synthesis Example 1 was performed except that 2.56 g was used. GPC analysis of the obtained resin showed that the weight average molecular weight thereof was 85700 in terms of standard polystyrene. The solid content in the solution was 20% by weight.

Synthesis Example 4 Instead of methyl methacrylate corresponding to the raw material of the repeating unit (C), isopropyl methacrylate represented by the formula (4):

[Chemical 4] The same procedure as in Synthesis Example 1 was performed except that 2.56 g was used. GPC analysis of the obtained resin showed that it had a weight average molecular weight of 57900 in terms of standard polystyrene. The solid content in the solution was 20% by weight.

Synthesis Example 5 Instead of methyl methacrylate corresponding to the raw material of the repeating unit (C), t-butyl methacrylate represented by the formula (5):

[Chemical 5] The same procedure as in Synthesis Example 1 was performed except that 2.56 g was used. When the GPC analysis of the obtained resin was performed, the weight average molecular weight was 62300 in terms of standard polystyrene. The solid content in the solution was 20% by weight.

Synthesis Example 6 Instead of methyl methacrylate corresponding to the raw material of the repeating unit (C), 2-methylpropyl methacrylate represented by the formula (6):

[Chemical 6] The same procedure as in Synthesis Example 1 was performed except that 2.56 g was used. When the GPC analysis of the obtained resin was performed, the weight average molecular weight was 49300 in terms of standard polystyrene. The solid content in the solution was 20% by weight.

Synthesis Example 7 Butyl methacrylate represented by the formula (7) instead of methyl methacrylate corresponding to the raw material of the repeating unit (C):

[Chemical 7] The same procedure as in Synthesis Example 1 was performed except that 2.56 g was used. When the GPC analysis of the obtained resin was performed, the weight average molecular weight was 58900 in terms of standard polystyrene. The solid content in the solution was 20% by weight.

Synthesis Example 8 Instead of methyl methacrylate corresponding to the raw material of the repeating unit (C), furfuryl methacrylate represented by the formula (8):

[Chemical 8] The same procedure as in Synthesis Example 1 was performed except that 2.56 g was used. When the GPC analysis of the obtained resin was performed, the weight average molecular weight was 17700 in terms of standard polystyrene. The solid content in the solution was 20% by weight.

Synthesis Example 9 2-Ethylhexyl methacrylate represented by the formula (9) instead of methyl methacrylate corresponding to the raw material of the repeating unit (C):

[Chemical 9] The same procedure as in Synthesis Example 1 was performed except that 2.56 g was used. GPC analysis of the obtained resin showed that the weight average molecular weight was 39,300 in terms of standard polystyrene. The solid content in the solution was 20% by weight.

Synthesis Example 10 Stearyl methacrylate represented by the formula (10) instead of methyl methacrylate corresponding to the raw material of the repeating unit (C):

[Chemical 10] The same procedure as in Synthesis Example 1 was performed except that 2.56 g was used. GPC analysis of the obtained resin showed that the weight average molecular weight was 79,700 in terms of standard polystyrene. The solid content in the solution was 20% by weight.

Synthesis Example 11 2,2,2-trifluoroethyl methacrylate represented by the formula (11) instead of methyl methacrylate corresponding to the raw material of the repeating unit (C):

[Chemical 11] The same procedure as in Synthesis Example 1 was performed except that 2.56 g was used. GPC analysis of the obtained resin showed that the weight average molecular weight was 8,800 in terms of standard polystyrene. The solid content in the solution was 20% by weight.

Synthesis Example 12 2,2,2-trichloroethyl methacrylate represented by the formula (12) instead of methyl methacrylate corresponding to the raw material of the repeating unit (C):

[Chemical 12] The same procedure as in Synthesis Example 1 was performed except that 2.56 g was used. GPC analysis of the obtained resin revealed that the weight average molecular weight thereof was 93400 in terms of standard polystyrene. The solid content in the solution was 20% by weight.

Synthesis Example 13 2-Ethoxyethyl methacrylate represented by the formula (13) in place of methyl methacrylate corresponding to the raw material of the repeating unit (C):

[Chemical 13] The same procedure as in Synthesis Example 1 was performed except that 2.56 g was used. When the GPC analysis of the obtained resin was performed, the weight average molecular weight was 69000 in terms of standard polystyrene. The solid content in the solution was 20% by weight.

Synthesis Example 14 Instead of methyl methacrylate corresponding to the raw material of the repeating unit (C), ethylene glycol monomethyl ether methacrylate represented by the formula (14):

[Chemical 14] The same procedure as in Synthesis Example 1 was performed except that 2.56 g was used. GPC analysis of the obtained resin showed that the weight average molecular weight thereof was 67400 in terms of standard polystyrene. The solid content in the solution was 20% by weight.

Synthesis Example 15 Butyl lactone methacrylate represented by the formula (15) instead of methyl methacrylate corresponding to the raw material of the repeating unit (C):

[Chemical 15] The same procedure as in Synthesis Example 1 was performed except that 2.56 g was used. When the GPC analysis of the obtained resin was performed, the weight average molecular weight was 66400 in terms of standard polystyrene. The solid content in the solution was 20% by weight.

Synthesis Example 16 5.44 g of benzyl methacrylate corresponding to the raw material of the repeating unit (A), 9.60 g of 2-hydroxypropyl methacrylate corresponding to the raw material of the repeating unit (B),
And 0.96 g of 2-ethylhexyl methacrylate represented by the formula (9), which corresponds to the raw material of the repeating unit (C), was dissolved in 64 g of propylene glycol monomethyl ether, and the reaction solution was heated to 70 ° C. A stream of nitrogen was passed through. Then, as a polymerization initiator, azobisisobutyronitrile AIBN (product of Junsei Chemical Co., Ltd.) 0.16
g was added. After stirring in a nitrogen atmosphere for 24 hours, 0.05 g of 4-methoxyphenol (product of Tokyo Kasei Co., Ltd.) was added as a polymerization terminator. When the GPC analysis of the obtained resin was performed, the weight average molecular weight in terms of standard polyethylene was 63600. The solid content in the solution was 20% by weight.

Synthesis Example 17 23.8 g of benzyl methacrylate corresponding to the raw material of the repeating unit (A), 32.2 g of 2-hydroxypropyl methacrylate corresponding to the raw material of the repeating unit (B),
And 14.0 g of ethyl methacrylate represented by the formula (2) corresponding to the raw material of the repeating unit (C) were dissolved in 280 g of propylene glycol monomethyl ether, and the reaction solution was heated to 70 ° C. Flushed with nitrogen. Then, 0.7 g of azobisisobutyronitrile AIBN (manufactured by Junsei Chemical Co., Ltd.) was added as a polymerization initiator. After stirring under a nitrogen atmosphere for 24 hours, 4-methoxyphenol (manufactured by Tokyo Kasei Co., Ltd.) 0.1 as a polymerization terminator
g was added. GPC analysis of the obtained resin showed that it had a weight average molecular weight of 549 in terms of standard polyethylene.
It was 00. The solid content in the solution was 20% by weight.

Synthesis Example 18 10.2 g of benzyl methacrylate corresponding to the raw material of the repeating unit (A) and 19.8 g of 2-hydroxypropyl methacrylate corresponding to the raw material of the repeating unit (B)
And propylene glycol monomethyl ether 120g
After being dissolved in, the reaction solution was heated to 70 ° C., and at the same time, nitrogen was flown into the reaction solution. Then, as a polymerization initiator, azobisisobutyronitrile AIBN (product of Junsei Chemical Co., Ltd.)
0.3 g was added. After stirring for 24 hours under a nitrogen atmosphere,
As a polymerization terminator, 0.05 g of 4-methoxyphenol (product of Tokyo Kasei Co., Ltd.) was added. G of the obtained resin
When PC analysis was performed, the weight average molecular weight was 61300 in terms of standard polystyrene. The solid content in the solution was 20%.

Synthesis Example 19 15.0 g of benzyl methacrylate corresponding to the raw material of the repeating unit (A) and 15.0 g of 2-hydroxypropyl methacrylate corresponding to the raw material of the repeating unit (B)
And propylene glycol monomethyl ether 120g
After being dissolved in, the reaction solution was heated to 70 ° C., and at the same time, nitrogen was flown into the reaction solution. Then, as a polymerization initiator, azobisisobutyronitrile AIBN (product of Junsei Chemical Co., Ltd.)
0.3 g was added. After stirring for 24 hours under a nitrogen atmosphere,
As a polymerization terminator, 0.05 g of 4-methoxyphenol (product of Tokyo Kasei Co., Ltd.) was added. G of the obtained resin
When PC analysis was performed, the weight average molecular weight was 61,000 in terms of standard polystyrene. The solid content in the solution was 20%.

Example 1 13.5 g of the reaction solution obtained in Synthesis Example 1, 3.4 g of hexamethoxymethylolmelamine as a crosslinking agent, and 0.2 g of pyridinium p-toluenesulfonate as a curing agent were mixed, and propylene glycol as a solvent was mixed. After adding 434.3 g of monomethyl ether and 48.3 g of propylene glycol monomethyl ether acetate, this was filtered using a polyethylene microfilter having a pore size of 0.10. Then, a polyethylene microfilter having a pore size of 0.05 μm was used. An antireflection film-forming composition was prepared by filtration. This solution was applied onto a silicon wafer using a spinner. The film was heated on a hot plate at 205 ° C. for 1 minute to form an antireflection film (film thickness 0.08 μm).

Examples 2 to 17 The same procedure as in Example 1 was repeated except that the reaction liquids obtained in Synthesis Examples 2 to 17 were used instead of the reaction liquids in Synthesis Example 1 to obtain Examples 2 to 17, respectively. . Table 2 shows the names of the compounds corresponding to the starting materials for the repeating unit (A), the repeating unit (B) and the repeating unit (C) used in Synthesis Examples 2 to 17 and their amounts used.

[Table 2]

Reference Example 1 13.5 g of the reaction solution obtained in Synthesis Example 18, 3.4 g of hexamethoxymethylolmelamine as a crosslinking agent, and 0.2 g of pyridinium p-toluenesulfonate as a curing agent.
Were mixed and the solvents propylene glycol monomethyl ether 434.3 and propylene glycol monomethyl ether acetate 48.3 g were added.
0 using a polyethylene microfilter,
Then, it filtered using the polyethylene micro filter with a pore size of 0.05 micrometer, and prepared the antireflection film formation composition. This solution was applied onto a silicon wafer using a spinner. Heat at 205 ° C for 1 minute on a hot plate,
An antireflection film (film thickness 0.08 μm) was formed.

Reference Example 2 Reference Example 2 was carried out in the same manner as Reference Example 1 except that the reaction liquid obtained in Synthesis Example 19 was used instead of the reaction liquid of Synthesis Example 18.

(Solvent Resistance Test) Each of the solutions obtained in Synthesis Examples 1 to 19 was applied onto a silicon wafer by a spinner. The film was heated on a hot plate at 205 ° C. for 1 minute to form an antireflection film (film thickness 0.23 μm). This antireflection film was immersed in a solvent used for photoresist, for example, ethyl lactate and propylene glycol monomethyl ether, and it was confirmed that it was insoluble in the solvent.

(Measurement of Surface Energy of Antireflection Film and Photoresist Film) The above Examples 1 to 17 and Reference Example 1,
Using methylene iodide and water droplets for the antireflection film and the photoresist film obtained from Example 2, the contact angle was measured on the solid surface, and the surface energy (mN / m) was calculated from the formulas (I) to (III). ) Was calculated. The results are shown in Table 3.

In Table 3, "Example 1" shows the measurement results of the antireflection film obtained in Example 1, and Examples 2 to 1 similarly.
7 and Reference Examples 1 and 2 are Examples 2 to 17 and Reference Example 1,
The measurement results of the antireflection film obtained in No. 2 are shown. And
A commercially available photoresist solution (Sumitomo Chemical Co., Ltd., trade name PAR710) was applied on a silicon wafer by a spinner and heated on a hot plate at 90 ° C. for 1 minute to form a photoresist film. The measurement results of the surface energy (mN / m) of this photoresist film are also shown.

[Table 3] As shown in Table 2, by using an antireflection film using the obtained resin used in Examples, the surface energy value is changed according to the surface energy value of the photoresist film coated on the upper layer. It is possible to This is to change the surface energy of the antireflection film using the copolymer resin in which the copolymerization ratio of the repeating unit (A), the repeating unit (B) and the repeating unit (C) is changed. You can

On the other hand, in the case of the copolymer resin composed of the repeating unit (A) and the repeating unit (B) used in Reference Examples 1 and 2, the relationship with the dry etching rate and the reflectance of the antireflection film. Considering the above, the amount of the repeating unit (A) introduced is restricted, and as a result, it is difficult to greatly change the surface energy of the antireflection film in accordance with the surface energy of the overcoating photoresist film.

(Formation of Film on Substrate) Photoresist used for evaluation (Sumitomo Chemical Co., Ltd., trade name PAR710)
Focus margin, which is one of the problems that can be solved by using Examples 16 and 17 that are close to the contact angle and surface energy value of the film, and Reference Example 2 that is far from the contact angle and surface energy value of the photoresist film. Was evaluated according to the following method.

In order to obtain the antireflection films of Examples 16 and 17 and Reference Example 2, the solutions obtained in Synthetic Examples 16, 17 and 19 were applied on a silicon wafer by a spinner. The film was heated on a hot plate at 205 ° C. for 1 minute to form an antireflection film (film thickness 0.078 μm). A commercially available photoresist solution (Sumitomo Chemical Co., Ltd., trade name PAR710) was applied to the upper layer of this antireflection film by a spinner and heated on a hot plate at 90 ° C. for 1 minute to form a photoresist film (film thickness). 0.33 μm) was formed.
A PAS5500 / 990 scanner manufactured by ASML (wavelength 193 nm, NA, σ: 0.63, 0.87 /
0.57 (Annuler), and the line width of the photoresist and the width between the lines are 0.13 after development.
The exposure was carried out through a mask having a thickness of 0.1 μm, that is, 0.13 μmL / S (dense line), and set to form 9 such lines. After that, baking is performed on a hot plate at 130 ° C. for 60 seconds, and after cooling, an industrial standard 60 second single paddle type process is performed.
It was developed with a 26N tetramethylammonium hydroxide developer.

The focus depth margin was determined as follows. That is, the exposure was performed while shifting the focus position vertically by 0.1 μm with respect to the optimum focus position, and a resist pattern was formed by the subsequent development processing. Then, out of the nine photoresist lines to be formed, seven or more lines were formed, and the case where the number of remaining lines was six or less was regarded as a failure. Then, the upper and lower widths of the shift of the focus position that can obtain the pass result are set as the focus depth margin. The respective results are shown in Table 4.

The photoresist line patterns (resist hem shape) obtained here all had a good straight hem shape.

[Table 4]

The focus depth margins of the antireflection films of Examples 16 and 17 obtained from the antireflection film-forming compositions of Synthesis Example 16 and Synthesis example 17 according to the present invention were compared with those of Reference Example 2. It was confirmed that it was wide. The surface energy of the used photoresist film is 43m
In contrast to N / m, the surface energy value of Example 16 is 42 mN / m, the surface energy value of Example 17 is 43 mN / m, and the surface energy difference is 0 to 1 mN.
Was / m. As a result, it is considered that a wide focus depth margin was obtained. On the other hand, in Reference Example 2, the value of the surface energy is 46 mN / m, the difference in the surface energy from the photoresist film is 3 mN / m, and the width of the focus depth margin is narrower than those in the sixteenth and seventeenth embodiments. It is a thing. It can be seen that the antireflection film of the example has a wide focus depth margin while maintaining a practical refractive index and optical absorption coefficient when exposed to exposure light of 193 nm.

In the present invention, attention is paid to the fact that the relationship of the surface energy at the interface between the photoresist film and the antireflection film has a great influence on the lithography process and the obtained resist shape, and the photoresist coated on the upper layer is The surface energy of the antireflection film is changed according to the magnitude of the surface energy, and the surface energy at the interface between the photoresist film and the antireflection film is adjusted by the antireflection film itself. This surface energy can be adjusted by changing the copolymerization ratio of the monomers of the resin used in the antireflection film-forming composition. Therefore,
It is possible to change the surface energy corresponding to various photoresists, which makes it possible to form a resist pattern with high dimensional accuracy. Therefore, when the method of the present invention is used, it is possible to obtain a wide focus depth margin and a high resolution at the time of exposure by making the surface energies of the antireflection film and the photoresist existing thereabove coincident or close to each other. . The obtained antireflection film is effective not only for preventing the reflection from the substrate but also for improving the adhesiveness of the photoresist. According to the present invention, the photoresist layer has high adhesion to an unexposed portion, has a high effect of preventing reflected light, further does not cause intermixing with the photoresist layer, and does not have a diffused substance in the photoresist during heating and drying. It is possible to obtain a composition for an antireflection film material having high resolution and excellent dependence on the photoresist film thickness, and to provide an excellent method for forming a photoresist pattern.

Continued front page    (72) Inventor Kenichi Mizusawa             1, 722, Tsuboi-cho, Funabashi-shi, Chiba Nissan Chemical             Industry Co., Ltd. Electronic Materials Research Center F term (reference) 2H025 AA02 AB16 AC04 AC08 CB14                       CB41 CC03 CC17 DA34                 5F046 PA07 PA09

Claims (10)

[Claims] 1. A method of forming an antireflection film under a photoresist using an antireflection film forming material containing a resin, a crosslinking agent and a solvent, wherein the surface energy of the antireflection film is
A method for forming an antireflection film, which comprises forming an antireflection film adjusted according to the amount of surface energy of a coated photoresist. 2. The resin according to claim 1, wherein the resin is a copolymer resin in which the copolymerization ratio of monomers constituting the resin is adjusted so that the surface energy of the antireflection film is adjusted. Method for forming antireflection film of the above. 3. The method for forming an antireflection film according to claim 1, wherein the resin contains a structure of a repeating unit (A) having at least an absorptive group. 4. The method according to claim 3, wherein the light-absorbing group contained in the repeating unit (A) in the resin is selected from the group consisting of an anthryl group, a naphthyl group, and a phenyl group. 5. The structure of the repeating unit (A) having a light-absorbing group, and the repeating unit (B) having a hydrophilic group, in the resin.
5. The method according to any one of claims 1 to 4, which comprises the structure (1) and the structure of the repeating unit (C) having a hydrophobic group. 6. The resin is an acrylic resin, and 1
000 to 1,000,000, and in the resin, the repeating unit (A) is 1 to 98% by weight, the repeating unit (B) is 1 to 98% by weight, and the repeating unit (C) is 1%. % To 98% by weight, and the total of repeating units (A), (B) and (C) does not exceed 100% by weight, forming an antireflection film according to any one of claims 1 to 5. Method. 7. The hydrophilic group contained in the repeating unit (B) in the resin is a hydroxyl group, an amino group, an isocyanate group,
The antireflection film according to any one of claims 1 to 6, which is selected from the group consisting of an amide group, a carboxyl group, a mercapto group, a methylol group, an acyloxyalkyl group, and a sulfonic acid group. Method. 8. The hydrophobic group contained in the repeating unit (C) in the resin has a linear or branched alkyl group having 1 to 20 carbon atoms, which may have a substituent, and a substituent. A group consisting of an aromatic ring group having 4 to 14 carbon atoms, an alicyclic group, a heteroaromatic ring group and a heterocyclic group, an alkoxy group having 1 to 20 carbon atoms, and a halogenated alkyl group having 1 to 20 carbon atoms 8. Any one of claims 1 to 7 selected from
Item 4. The method for forming an antireflection film as described in the item. 9. The antireflection film according to claim 1, wherein the surface energy of the antireflection film is adjusted to match the surface energy of the photoresist. Forming method. 10. A method of manufacturing a semiconductor device using a lithographic process, comprising forming an antireflection film on a substrate, coating a photoresist, and then exposing and developing the semiconductor device, according to any one of claims 1 to 8. By using the antireflection film formed by the method described above, the surface energy of the antireflection film is adjusted so as to match the magnitude of the surface energy of the overcoat photoresist at the interface between the photoresist and the antireflection film. A method for manufacturing a semiconductor device, comprising: