JP5257009B2 - Resist underlayer film forming composition, resist underlayer film forming method, and pattern forming method - Google Patents

Description

  The present invention relates to a resist underlayer film forming composition for a multilayer resist process suitable for microfabrication in a lithography process using various types of radiation, particularly for the manufacture of highly integrated circuit elements, a resist underlayer film forming method, and a pattern forming method. . More specifically, a composition for forming a resist underlayer film that is excellent in etching resistance, hardly bends in a dry etching process, and can form an underlayer film that can transfer a resist pattern to a substrate to be processed with high reproducibility, The present invention relates to a resist underlayer film forming method and a pattern forming method.

  2. Description of the Related Art A semiconductor device manufacturing process includes a number of steps of laminating a plurality of work films on a silicon wafer and patterning the work films into a desired pattern. In the patterning of the film to be processed, first, a photosensitive material generally called a resist is deposited on the film to be processed to form a resist film, and a predetermined region of the resist film is exposed. Next, the exposed or unexposed portion of the resist film is developed and removed to obtain a resist pattern on which a predetermined pattern is formed. Thereafter, using the resist pattern as an etching mask, the film to be processed is patterned by dry etching.

  In such a process, an ultraviolet light such as an ArF excimer laser is used as an exposure light source for exposing a resist film. Recently, there is an increasing demand for miniaturization of a large scale integrated circuit (LSI). The required resolution has become below the wavelength of exposure light (ultraviolet light). Thus, when the required resolution is less than or equal to the wavelength of the exposure light, the exposure process tolerance such as the exposure tolerance and the focus tolerance is insufficient. In order to compensate for this lack of exposure process tolerance, it is effective to reduce the resist film thickness to improve resolution, but reducing the film thickness is necessary for etching the film to be processed. It becomes difficult to ensure a sufficient resist film thickness.

  For this reason, a resist underlayer film (hereinafter sometimes simply referred to as “underlayer film”) is formed between the film to be processed and the resist film, and the resist pattern is temporarily transferred to the underlayer film to form the underlayer film pattern. After forming the film, a process for transferring the pattern to the film to be processed using the lower layer film pattern as an etching mask has been studied.

  In such a process, the lower layer film is preferably made of a material having etching resistance, and the material includes, for example, a benzene ring that absorbs energy during etching and is known to have etching resistance. A composition containing a resin, in particular, a thermosetting phenol novolak, a composition containing a polymer having an acenaphthylene skeleton, and the like have been proposed (see, for example, Patent Documents 1 and 2). A composition containing a copolymer of a styrene derivative or an allylbenzene derivative and a nortricyclene derivative has also been proposed (see, for example, Patent Document 3).

JP 2001-40293 A JP 2000-143937 A JP 2008-65303 A

  However, with further miniaturization of the etching pattern, overetching of the resist underlayer film has become a big problem, and even underlayer films formed by the compositions described in Patent Documents 1 to 3 are sufficiently etched. Development of a composition (a composition for forming a resist underlayer film) capable of forming a lower layer film having no resistance and having further improved etching resistance is demanded.

  The present invention has been made to solve the above-described problems of the prior art, has excellent etching resistance, hardly bends in a dry etching process, and faithfully transfers a resist pattern to a substrate to be processed with high reproducibility. It is an object of the present invention to provide a resist underlayer film forming composition, a resist underlayer film forming method, and a pattern forming method capable of forming an underlayer film that can be formed.

  The present invention provides the following resist underlayer film forming composition, resist underlayer film forming method, and pattern forming method.

[1] contains a novolak resin and an organic solvent containing a pyrene skeleton having a hydroxyl group, wherein the novolak resin resist underlayer film forming composition further contains a naphthalene skeleton having two or more phenolic hydroxyl groups.

[ 2 ] The resist underlayer film forming composition according to [1 ], wherein the pyrene skeleton is derived from dihydroxypyrene.

[ 3 ] The resist underlayer film forming composition according to [1] or [2] , further including at least one of an acid generator and a crosslinking agent.

[ 4 ] The resist underlayer film forming composition according to any one of [1] to [ 3 ] is applied onto a substrate to be processed to form a coating film, and the formed coating film is applied to the substrate to be processed. And forming a resist underlayer film on the substrate to be processed.

[ 5 ] The method for forming a resist underlayer film according to [ 4 ], wherein the baking is performed in an atmosphere containing oxygen.

[ 6 ] (1) Step of obtaining a resist film by applying a resist composition on the resist underlayer film formed by the method for forming a resist underlayer film according to [ 4 ] or [ 5 ] The resist film is selectively irradiated with radiation to expose the resist film (2), the exposed resist film is developed to form a resist pattern (3), and the resist (4) forming a predetermined pattern on the substrate to be processed by dry etching the resist underlayer film and the substrate to be processed using a pattern as a mask.

  The composition for forming a resist underlayer film of the present invention is excellent in etching resistance, hardly bends in a dry etching process, and can form an underlayer film capable of transferring a resist pattern to a substrate to be processed with high reproducibility. This is an effect.

  The method for forming a resist underlayer film of the present invention is excellent in etching resistance, is not easily bent in a dry etching process, and can form an underlayer film capable of faithfully transferring a resist pattern to a substrate to be processed with high reproducibility. There is an effect.

  The pattern forming method of the present invention has an effect that a resist pattern can be transferred to a substrate to be processed with high reproducibility.

  Hereinafter, the best mode for carrying out the present invention will be described, but the present invention is not limited to the following embodiment. That is, it is understood that modifications and improvements as appropriate to the following embodiments are also within the scope of the present invention based on ordinary knowledge of those skilled in the art without departing from the spirit of the present invention. Should be.

[1] Composition for forming a resist underlayer film:
Resist underlayer film forming composition of the present invention contains a novolak resin and an organic solvent containing a pyrene skeleton having a hydroxyl group, a novolak resin, and further comprising a naphthalene skeleton having two or more phenolic hydroxyl groups is there. Such a composition for forming a resist underlayer film has excellent etching resistance, is difficult to bend in a dry etching process, and can form an underlayer film capable of faithfully transferring a resist pattern to a substrate to be processed with high reproducibility. .

In other words, the composition for forming a resist underlayer film of the present invention can be suitably used for fine processing in a lithography process using various types of radiation, and can form a resist underlayer film having excellent etching resistance. Therefore, it can be particularly suitably used for a pattern forming method using a multilayer resist process in a region finer than 90 nm (ArF, ArF, F ₂ , EUV, nanoimprint in immersion exposure) among multilayer resist processes. .

[1-1] Novolak resin:
Novolak resin, as described above, viewed contains a pyrene skeleton having a hydroxyl group, the novolak resins are those which further include a naphthalene skeleton having two or more phenolic hydroxyl groups. When such a novolak resin has a hydroxyl group, the hydroxyl group reacts with a hydrogen atom of the pyrene skeleton, and the electron density of pyrene is increased by the hydroxyl group, thereby improving the crosslinking reactivity.

  The aldehyde group possessed by the pyrene skeleton has crosslinkability and has an effect of reducing the hydrogen content of the novolac resin. By reducing the hydrogen content of the novolak resin, there is an advantage that the bending resistance of the lower layer film pattern during etching is improved.

  The pyrene skeleton has one or more hydroxyl groups, preferably 2 to 8, and more preferably 2 to 4. In the case of not having a hydroxyl group or an aldehyde group, there is a problem that the crosslinking reactivity of the novolak resin is lowered or the hydrogen content of the novolak resin is not sufficiently lowered. The upper layer film formed on the lower layer film may cause intermixing. Further, the lower layer film may be easily bent in the dry etching process.

  The pyrene skeleton may have other substituents in addition to the aldehyde group and the hydroxyl group. Examples of other substituents include an alkyl group, an aromatic ring, and a hetero atom.

  The pyrene skeleton is not particularly limited as long as it satisfies the above conditions, but is preferably derived from dihydroxypyrene. When derived from dihydroxypyrene, the electron density of pyrene is increased by two hydroxyl groups, so that the crosslinking reactivity can be improved, and the hydrogen content of the novolak resin can be reduced. is there.

  The novolak resin may further contain other skeletons in addition to the pyrene skeleton. Examples of other skeletons include a naphthalene skeleton having two or more phenolic hydroxyl groups, a phenol skeleton, a naphthol skeleton, and an anthracene skeleton. Examples include a nor skeleton. Among these, a naphthalene skeleton having two or more phenolic hydroxyl groups is preferable. Of the naphthalene skeletons having two or more phenolic hydroxyl groups, a dihydroxynaphthalene skeleton is preferable. Thus, when the naphthalene skeleton having two or more phenolic hydroxyl groups is further included, the above hydroxyl group of the naphthalene skeleton having two or more phenolic hydroxyl groups acts as a cross-linking site, and therefore, there is an advantage that intermixing can be prevented. is there.

  The novolak resin can be obtained, for example, by reacting pyrene having at least one of an aldehyde group and a hydroxyl group in the molecule with a condensing agent. When the novolak resin thus obtained is used, the hydroxyl group reacts with a hydrogen atom in the pyrene skeleton, so that there is an advantage that a lower layer film having a high film density can be formed.

  The condensing agent is not particularly limited as long as it can undergo a condensation reaction with the above pyrene. For example, saturated aliphatic aldehydes such as formaldehyde, paraformaldehyde, acetaldehyde and propylaldehyde; unsaturated fats such as acrolein and methacrolein Examples include aromatic aldehydes; heterocyclic aldehydes such as furfural; aromatic aldehydes such as benzaldehyde, naphthylaldehyde, and anthraldehyde. Among these, formaldehyde, paraformaldehyde, and furfural are preferable. In addition, a condensing agent may be used individually by 1 type, and may use 2 or more types.

  The amount of the condensing agent used is preferably 0.01 to 100 parts by mass, more preferably 0.1 to 50 parts by mass, and 1 to 10 parts by mass with respect to 100 parts by mass of the pyrene. It is particularly preferred. If the content is less than 0.01 parts by mass, the cross-linking reaction between the pyrene and the condensing agent does not sufficiently occur, so that the lower layer film and the upper layer film formed on the lower layer film may cause intermixing. There is. On the other hand, if it exceeds 100 parts by mass, the carbon content of the lower layer film is lowered, so that the etching resistance may be lowered.

  In order to obtain the novolak resin, other compounds (i) may be used in addition to the pyrene and the condensing agent.

  Examples of other compounds (i) include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o-acetoxystyrene, m-acetoxystyrene, p-acetoxystyrene, p- Styrene derivatives such as t-butoxystyrene; vinyl carboxylates such as vinyl acetate, vinyl propionate and vinyl caproate; vinyl cyanide compounds such as (meth) acrylonitrile and α-chloroacrylonitrile; methyl (meth) acrylate, ethyl ( Unsaturated carboxylic ester compounds such as (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, n-hexyl (meth) acrylate, glycidyl (meth) acrylate;

  Unsaturated group-containing unsaturated carboxylic acid ester compounds such as ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, vinyl (meth) acrylate, dimethylvinylmethacryloyloxymethylsilane; 2-chloroethyl vinyl ether, chloroacetic acid Halogen-containing vinyl compounds such as vinyl and allyl chloroacetate; hydroxyl-containing vinyl compounds such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate and (meth) allyl alcohol;

  Amide group-containing vinyl compounds such as (meth) acrylamide and crotonic acid amide; Carboxyl group-containing vinyl compounds such as 2-methacryloyloxyethylsuccinic acid and 2-methacryloyloxyethylmaleic acid; benzene, naphthalene, anthracene, phenanthrene, acenaphthene Unsubstituted aromatic hydrocarbon compounds such as

  Alkyl-substituted aromatic hydrocarbon compounds such as toluene, m-xylene, p-xylene and 1-methylnaphthalene; carboxyl group-substituted aromatic hydrocarbon compounds such as benzoic acid, 1-naphthalenecarboxylic acid and 9-anthracenecarboxylic acid; aniline Amino group-substituted aromatic hydrocarbon compounds such as chlorobenzene, bromobenzene, and other halogenated aromatic hydrocarbon compounds;

  Butadiene, vinylbenzene, divinylbenzene, dicyclopentadiene, tetrahydroindene, 4-vinylcyclohexene, 5-vinylnorborna-2-ene, α-pinene, β-pinene, limonene, 5-vinylnorbornadiene, 1-vinylnaphthalene, 2- Examples thereof include vinyl compounds such as vinyl naphthalene, 9-vinyl anthracene and 9-vinyl carbazole. Among these, divinylbenzene, dicyclopentadiene, 5-vinylnorborna-2-ene, 1-vinylnaphthalene, and 2-vinylnaphthalene are preferable. In addition, another compound may be used individually by 1 type and may use 2 or more types.

  The amount of the other compound (i) used is preferably 0.01 to 100 parts by mass, more preferably 0.1 to 50 parts by mass, with respect to 100 parts by mass of the pyrene. The part by mass is particularly preferred. If the content is less than 0.01 parts by mass, the cross-linking reaction between the pyrene and the condensing agent does not sufficiently occur, so that the lower layer film and the upper layer film formed on the lower layer film may cause intermixing. There is. On the other hand, if it exceeds 100 parts by mass, the carbon content of the lower layer film is lowered, so that the etching resistance may be lowered.

  Conventionally known conditions can be adopted as the reaction conditions for obtaining the novolak resin. Specifically, it can be carried out by reacting the pyrene with the condensing agent at the following reaction temperature and reaction time in the presence of an acid catalyst. The reaction temperature is preferably 40 to 200 ° C, more preferably 60 to 150 ° C, and particularly preferably 70 to 100 ° C. The reaction time varies depending on the reaction temperature, but is preferably 30 minutes to 72 hours, more preferably 1 to 24 hours, and particularly preferably 2 to 10 hours.

  Examples of the acid catalyst include mineral acids such as sulfuric acid, phosphoric acid and perchloric acid; organic sulfonic acids such as p-toluenesulfonic acid; carboxylic acids such as formic acid and oxalic acid. Although the usage-amount of an acid catalyst changes with kinds of acid catalyst to be used, it is preferable that it is 0.001-30 mass parts with respect to 100 mass parts of total amounts of the said pyrene and a condensing agent, 0.01-10 It is more preferable that it is a mass part, and it is especially preferable that it is 0.1-5 mass part.

  The novolak resin preferably has a polystyrene-equivalent weight average molecular weight (hereinafter referred to as “Mw”) measured by gel permeation column chromatography of 1,000 to 5,000, It is more preferable that it is 000-3,000, and it is especially preferable that it is 1,000-2,000. There exists a possibility that the applicability | paintability of the composition for resist underlayer film formation may fall that the said weight average molecular weight is less than 1,000. On the other hand, if it exceeds 5,000, the film density of the lower layer film may be lowered.

[1-2] Organic solvent:
The organic solvent is not particularly limited as long as it can dissolve the novolak resin. Specifically, ethylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-n-butyl ether; ethylene glycol monomethyl ether acetate, ethylene glycol mono Ethylene glycol monoalkyl ether acetates such as ethyl ether acetate, ethylene glycol mono-n-propyl ether acetate, ethylene glycol mono-n-butyl ether acetate; diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di-n-propyl ether, diethylene glycol di- Diethylene glycol such as n-butyl ether Le dialkyl ethers; triethylene glycol dimethyl ether, triethylene glycol dialkyl ethers such as triethylene glycol diethyl ether;

  Propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-n-butyl ether; propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol di-n -Propylene glycol dialkyl ethers such as propyl ether and propylene glycol di-n-butyl ether; propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol mono-n-propyl ether acetate, propylene glycol mono-n-butyl ether acetate Propylene glycol such as Roh alkyl ether acetates;

  Lactic acid esters such as methyl lactate, ethyl lactate, n-propyl lactate, i-propyl lactate, n-butyl lactate, i-butyl lactate; methyl formate, ethyl formate, n-propyl formate, i-propyl formate, n-formate Butyl, i-butyl formate, n-amyl formate, i-amyl formate, methyl acetate, ethyl acetate, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, n-amyl acetate, i-acetate -Amyl, n-hexyl acetate, methyl propionate, ethyl propionate, n-propyl propionate, i-propyl propionate, n-butyl propionate, i-butyl propionate, methyl butyrate, ethyl butyrate, n-propyl butyrate Aliphatic carboxylic acid esters such as i-propyl butyrate, n-butyl butyrate and i-butyl butyrate;

  Ethyl hydroxyacetate, ethyl 2-hydroxy-2-methylpropionate, methyl 3-methoxy-2-methylpropionate, methyl 2-hydroxy-3-methylbutyrate, ethyl methoxyacetate, ethyl ethoxyacetate, methyl 3-methoxypropionate , Ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, 3-methoxypropyl acetate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutylpropionate, 3 -Other esters such as methyl-3-methoxybutyl butyrate, methyl acetoacetate, methyl pyruvate, ethyl pyruvate;

  Aromatic hydrocarbons such as toluene and xylene; ketones such as methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, 2-heptanone, 3-heptanone, 4-heptanone, cyclohexanone; N-methylformamide, N , N-dimethylformamide, N-methylacetamide, N, N-dimethylacetamide, N-methylpyrrolidone and other amides; γ-butyrolactone and other lactones.

  Among these, propylene glycol monomethyl ether, ethylene glycol monoethyl ether acetate, ethyl lactate, n-butyl acetate, ethyl 3-ethoxypropionate, methyl 3-methoxypropionate, 2-heptanone, cyclohexanone, and γ-butyrolactone are preferable. In addition, an organic solvent may be used individually by 1 type, and may use 2 or more types.

  The content of the organic solvent is preferably such that the solid content concentration of the resist underlayer film forming composition is 5 to 80% by mass, more preferably 5 to 40% by mass. It is particularly preferable that the amount be ˜30% by mass. If the solid content concentration of the composition for forming a resist underlayer film is less than 5% by mass, a sufficient film thickness cannot be obtained, so that etching may not be possible. On the other hand, if it exceeds 80% by mass, the novolac resin may be precipitated because the solubility is not sufficient.

  The resist underlayer film forming composition of the present invention preferably further contains at least one of an acid generator and a crosslinking agent in addition to the novolak resin and the organic solvent.

[1-3] Acid generator:
The acid generator is a component that generates an acid upon exposure or heating. By containing such an acid generator, the reaction with the hydrogen atom of the pyrene skeleton is promoted, so that there is an advantage that the film density of the lower layer film is improved and the etching resistance is improved. In the present specification, an acid generator that generates an acid upon exposure is referred to as a “photoacid generator”, and an acid generator that generates an acid upon heating is referred to as a “thermal acid generator”. Moreover, a photo-acid generator and a thermal acid generator can also be used together as an acid generator.

  Specific examples of photoacid generators include diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium pyrenesulfonate, diphenyliodonium n-dodecylbenzenesulfonate, diphenyliodonium 10-camphorsulfonate, diphenyliodonium naphthalene. Sulfonate, diphenyliodonium hexafluoroantimonate, bis (4-t-butylphenyl) iodonium trifluoromethanesulfonate, bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate, bis (4-t-butylphenyl) Iodonium n-dodecylbenzenesulfonate, bis (4-t-butylphenyl) iodonium 1 - camphorsulfonate, bis (4-t- butylphenyl) iodonium naphthalene sulfonate, bis (4-t- butylphenyl) iodonium hexafluoroantimonate,

  Triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium n-dodecylbenzenesulfonate, triphenylsulfonium naphthalenesulfonate, triphenylsulfonium 10-camphorsulfonate, triphenylsulfonium hexafluoroantimonate, 4 -Hydroxyphenyl phenyl methylsulfonium p-toluenesulfonate, 4-hydroxyphenyl benzyl methylsulfonium p-toluenesulfonate,

  Cyclohexyl methyl 2-oxocyclohexylsulfonium trifluoromethanesulfonate, 2-oxocyclohexyldicyclohexylsulfonium trifluoromethanesulfonate, 2-oxocyclohexyldimethylsulfonium trifluoromethanesulfonate, 1-naphthyldimethylsulfonium trifluoromethanesulfonate, 1-naphthyldiethylsulfonium trifluoromethanesulfonate 4-cyano-1-naphthyldimethylsulfonium trifluoromethanesulfonate, 4-cyano-1-naphthyldiethylsulfonium trifluoromethanesulfonate, 4-nitro-1-naphthyldimethylsulfonium trifluoromethanesulfonate, 4-nitro-1-naphthyldiethylsulfonium trifluoro Lome Sulfonate, 4-methyl-1-naphthyldimethylsulfonium trifluoromethanesulfonate, 4-methyl-1-naphthyldiethylsulfonium trifluoromethanesulfonate, 4-hydroxy-1-naphthyldimethylsulfonium trifluoromethanesulfonate, 4-hydroxy-1-naphthyldiethyl Sulfonium trifluoromethanesulfonate,

  1- (4-hydroxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-methoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-ethoxynaphthalene-1- Yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-methoxymethoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-ethoxymethoxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethane Sulfonate, 1- (4- (1-methoxyethoxy) naphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4- (2-methoxyethoxy) naphthalene 1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-methoxycarbonyloxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-ethoxycarbonyloxynaphthalen-1-yl) tetrahydrothio Phenium trifluoromethanesulfonate, 1- (4-n-propoxycarbonyloxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate,

  1- (4-i-propoxycarbonyloxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-n-butoxycarbonyloxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, (4-t-butoxycarbonyloxynaphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4- (2-tetrahydrofuranyloxy) naphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4- (2-Tetrahydropyranyloxy) naphthalen-1-yl) tetrahydrothiophenium trifluoromethanesulfonate, 1- (4-benzyloxy) tetrahydrothiophenium trifluoro Methanesulfonate, 1- (naphthyl acetamide methyl) onium salt photoacid generators such as tetrahydrothiophenium trifluoromethanesulfonate;

  Halogen-containing compound-based photoacid generators such as phenylbis (trichloromethyl) -s-triazine, 4-methoxyphenylbis (trichloromethyl) -s-triazine, 1-naphthylbis (trichloromethyl) -s-triazine; 2-naphthoquinonediazide-4-sulfonyl chloride, 1,2-naphthoquinonediazide-5-sulfonyl chloride, 1,3,4-naphthoquinonediazide-4-sulfonic acid ester of 2,3,4,4′-tetrahydroxybenzophenone or 1, Diazoketone compound photoacid generators such as 2-naphthoquinonediazide-5-sulfonic acid ester; sulfone compound photoacid generators such as 4-trisphenacylsulfone, mesitylphenacylsulfone, and bis (phenylsulfonyl) methane Benzoin tosylate, pyrogallol Lith (trifluoromethanesulfonate), nitrobenzyl-9,10-diethoxyanthracene-2-sulfonate, trifluoromethanesulfonylbicyclo [2,2,1] hept-5-ene-2,3-dicarbodiimide, N-hydroxysuccinimide Examples include sulfonic acid compound photoacid generators such as trifluoromethanesulfonate and 1,8-naphthalenedicarboxylic acid imide trifluoromethanesulfonate.

  Among these, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium pyrenesulfonate, diphenyliodonium n-dodecylbenzenesulfonate, diphenyliodonium 10-camphorsulfonate, diphenyliodonium naphthalenesulfonate, bis (4-t -Butylphenyl) iodonium trifluoromethanesulfonate, bis (4-t-butylphenyl) iodonium nonafluoro-n-butanesulfonate, bis (4-t-butylphenyl) iodonium n-dodecylbenzenesulfonate, bis (4-t-butyl) Phenyl) iodonium 10-camphorsulfonate, bis (4-tert-butylphenyl) iodoni Arm naphthalene sulfonate, and the like are preferable. In addition, a photo-acid generator may be used individually by 1 type, and may use 2 or more types.

  Specific examples of the thermal acid generator include 2,4,4,6-tetrabromocyclohexadienone, benzoin tosylate, 2-nitrobenzyl tosylate, and alkyl sulfonates. In addition, a thermal acid generator may be used individually by 1 type, and may use 2 or more types.

  The content of the acid generator is preferably 30 parts by mass or less, more preferably 1 to 20 parts by mass, and particularly preferably 3 to 10 parts by mass with respect to 100 parts by mass of the novolak resin. . When the composition for forming a resist underlayer film contains an acid generator, a crosslinking reaction can be effectively caused between molecular chains of the novolak resin at a relatively low temperature including normal temperature.

[1-4] Crosslinking agent:
The cross-linking agent prevents intermixing between the lower layer film obtained by curing the resist underlayer film forming composition and the resist film formed on this lower layer film, and further the generation of cracks in the lower layer film It is a component which has the effect | action which prevents. As such a crosslinking agent, polynuclear phenols and various commercially available curing agents can be used. Moreover, these can also be used together.

  Specific examples of polynuclear phenols include binuclear phenols such as 4,4′-biphenyldiol, 4,4′-methylenebisphenol, 4,4′-ethylidenebisphenol, and bisphenol A; 4,4 ′, 4 "Trimethylphenols such as" -methylidenetrisphenol, 4,4 '-(1- (4- (1- (4-hydroxyphenyl) -1-methylethyl) phenyl) ethylidene) bisphenol "; polyphenols such as novolak Among these, 4,4 ′-(1- (4- (1- (4-hydroxyphenyl) -1-methylethyl) phenyl) ethylidene) bisphenol, novolac, etc. are preferable. Polynuclear phenols may be used alone or in combination of two or more.

  As commercially available curing agents, specifically, 2,3-tolylene diisocyanate, 2,4-tolylene diisocyanate, 3,4-tolylene diisocyanate, 3,5-tolylene diisocyanate, 4,4 Diisocyanates such as' -diphenylmethane diisocyanate, hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate; hereinafter referred to as “Epicoat 812”, 815, 826, 828, 834, 836, 871, 1001, 1004, 1007, 1009, 1031 (above made by Yuka Shell Epoxy), "Araldite 6600", 6700, 6800, 502, 6071, 6084 6097, 6099 (above, manufactured by Ciba Geigy), "DER331", 332, 333, 661 same 644, the 667 (manufactured by Dow Chemical Co.) epoxy compounds such as;

  "Cymel 300", 301, 303, 350, 370, 771, 325, 327, 703, 712, 701, 272, 202, "My Coat 506", 508 ( As described above, melamine type curing agents such as Mitsui Cyanamid Co., Ltd .; “Cymel 1123”, 1123-10, 1128, “My Coat 102”, 105, 106, 130 (above, Mitsui Cyanamid Co., Ltd.), etc. Benzoguanamine-based curing agents, such as “Cymel 1170”, 1172 (above, manufactured by Mitsui Cyanamid), glycoluril-based curing agents such as “Nikalac N-2702” (manufactured by Sanwa Chemical), and the like. Among these, melamine type curing agents, glycoluril type curing agents and the like are preferable. In addition, a hardening | curing agent may be used individually by 1 type, and may use 2 or more types.

  The content of the crosslinking agent is preferably 30 parts by mass or less, more preferably 10 parts by mass or less, with respect to 100 parts by mass of the novolak resin.

[1-5] Other components:
The composition for forming a resist underlayer film of the present invention can contain other components as long as the desired effects are not impaired. Other components are components having functions such as preventing intermixing between the lower layer film and the resist film and improving the coating property of the composition for forming the resist lower layer film, such as a binder resin and a radiation absorber. , Surfactants, storage stabilizers, antifoaming agents, adhesion aids and the like.

  As the binder resin, various thermoplastic resins and thermosetting resins can be used. Specific examples of the thermoplastic resin include polyethylene, polypropylene, poly-1-butene, poly-1-pentene, poly-1-hexene, poly-1-heptene, poly-1-octene, poly-1-decene, Α-olefin polymers such as poly-1-dodecene, poly-1-tetradecene, poly-1-hexadecene, poly-1-octadecene, and polyvinylcycloalkane; poly-1,4-pentadiene, poly-1,4 Non-conjugated diene polymers such as hexadiene and poly-1,5-hexadiene; α, β-unsaturated aldehyde polymers; poly (methyl vinyl ketone), poly (aromatic vinyl ketone), poly (cyclic vinyl ketone) ), Etc .; (meth) acrylic acid, α-chloroacrylic acid, (meth) acrylate, (meth) acrylic acid Polymers of α, β-unsaturated carboxylic acids or derivatives thereof such as tellurium and (meth) acrylic acid halides; α, β-unsaturated polymers of poly (meth) acrylic anhydride and maleic anhydride Polymers of saturated carboxylic acid anhydrides; Polymers of unsaturated polybasic carboxylic acid esters such as methylenemalonic acid diester and itaconic acid diester;

  Polymers of diolefin carboxylic acid esters such as sorbic acid ester and muconic acid ester; Polymers of α, β-unsaturated carboxylic acid thioesters such as (meth) acrylic acid thioester and α-chloroacrylic acid thioester; ) Polymers of (meth) acrylonitrile such as acrylonitrile and α-chloroacrylonitrile or derivatives thereof; Polymers of (meth) acrylamide or derivatives thereof such as (meth) acrylamide, N, N-dimethyl (meth) acrylamide; Polymers of metal compounds; Polymers of vinyloxy metal compounds; Polyimines; Polyethers such as polyphenylene oxide, poly-1,3-dioxolane, polyoxirane, polytetrahydrofuran, polytetrahydropyran; Polysulfides; Polysulfonamides Polypeptides; Polyamides such as nylon 66 and nylon 1 to nylon 12; Polyesters such as aliphatic polyester, aromatic polyester, alicyclic polyester, and polycarbonate; Polyureas; Polysulfones; Polyazines; Polyamines Polyaromatic ketones, polyimides, polybenzimidazoles, polybenzoxazoles, polybenzothiazoles, polyaminotriazoles, polyoxadiazoles, polypyrazoles, polytetrazoles, polyquinoxalines, polytriazines Polybenzoxazinones; polyquinolines; polyanthrazolins and the like.

  The thermosetting resin is a component that is cured by heating and becomes insoluble in a solvent, and has an action of preventing intermixing between the lower layer film and the resist film (upper layer film) formed thereon. Specific examples of thermosetting resins include thermosetting acrylic resins, phenol resins, urea resins, melamine resins, amino resins, aromatic hydrocarbon resins, epoxy resins, alkyd resins. Etc. Among these, urea resins, melamine resins, aromatic hydrocarbon resins and the like are preferable.

  In addition, binder resin may be used individually by 1 type and may use 2 or more types. The content of the binder resin is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less with respect to 100 parts by mass of the novolac resin.

  Examples of the radiation absorber include oil-soluble dyes, disperse dyes, basic dyes, methine dyes, pyrazole dyes, imidazole dyes, hydroxyazo dyes, and the like; bixin derivatives, norbixine, stilbene, 4,4 Fluorescent brighteners such as' -diaminostilbene derivatives, coumarin derivatives, pyrazoline derivatives; UV absorbers such as hydroxyazo dyes, trade names “Tinuvin 234” and 1130 (above, manufactured by Ciba Geigy); anthracene derivatives, There are aromatic compounds such as anthraquinone derivatives. In addition, a radiation absorber may be used individually by 1 type and may use 2 or more types. The content of the radiation absorber is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less with respect to 100 parts by mass of the novolak resin.

  The surfactant is a component having an action of improving coating properties, striation, wettability, developability and the like. Examples of such surfactants include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene-n-octylphenyl ether, polyoxyethylene-n-nonylphenyl ether, and polyethylene. Nonionic surfactants such as glycol dilaurate and polyethylene glycol distearate, and “KP341” (manufactured by Shin-Etsu Chemical Co., Ltd.), “Polyflow No. 75”, and No. 95 (above, manufactured by Kyoeisha Yushi Chemical Co., Ltd.),

  "F Top EF101", EF204, EF303, EF352 (above, manufactured by Tochem Products), "Megafuck F171", F172, F173 (above, manufactured by Dainippon Ink and Chemicals), "Florade FC430 FC431, FC135, FC93 (manufactured by Sumitomo 3M Co., Ltd.), Asahi Guard AG710, Surflon S382, SC101, SC102, SC103, SC104, SC105, SC106 (above, Asahi Glass Co., Ltd.). In addition, surfactant may be used individually by 1 type and may use 2 or more types. The content of the surfactant is preferably 5 parts by mass or less, and more preferably 1 part by mass or less with respect to 100 parts by mass of the novolak resin.

[2] Method for forming resist underlayer film:
The method for forming a resist underlayer film of the present invention comprises forming a coating film by applying the resist underlayer film forming composition of the present invention onto a substrate to be processed, and firing the formed coating film together with the substrate to be processed. This is a method of forming a resist underlayer film on a substrate to be processed. According to such a method, it is possible to form a lower layer film that is excellent in etching resistance, hardly bends in the dry etching process, and can transfer the resist pattern to the substrate to be processed with high reproducibility. That is, a substrate with a resist underlayer film can be obtained satisfactorily.

  As the substrate to be processed, for example, an insulating film such as silicon oxide, silicon nitride, silicon oxynitride, polysiloxane, etc., all of which are “Black Diamond” (manufactured by AMAT), “Silk” (manufactured by Dow Chemical Company). ), An interlayer insulating film such as a wafer coated with a low dielectric insulating film such as “LKD5109” (manufactured by JSR) can be used. As the substrate to be processed, a patterned substrate such as a wiring groove (trench) or a plug groove (via) can be used.

  A conventionally known method can be adopted as a method for forming the coating film, and examples thereof include a spin coating method.

  The thickness of the coating film is preferably such that the resulting resist underlayer film has a thickness of 100 to 20000 nm.

  The firing conditions are not particularly limited, but the temperature is preferably 80 to 500 ° C, more preferably 150 to 450 ° C, and particularly preferably 250 to 350 ° C. When the temperature is lower than 80 ° C., the reaction between the hydroxyl group in the pyrene skeleton and the hydrogen atom hardly occurs, and the lower layer film and the upper layer film on the lower layer film may cause intermixing. On the other hand, if it exceeds 500 ° C., the lower layer film may be decomposed.

  Firing can be performed in an inert gas atmosphere or an oxygen-containing atmosphere (oxygen atmosphere), but is preferably performed in an oxygen-containing atmosphere. By firing in an atmosphere containing oxygen, the reaction between the hydroxyl group and the hydrogen atom in the pyrene skeleton is promoted, so that there is an advantage that the film density of the lower layer film is improved and the etching resistance is improved. Here, examples of the inert gas include nitrogen gas, argon gas, helium gas, xenon gas, and krypton gas.

  When firing in an oxygen atmosphere, the oxygen concentration is preferably 1 to 70%, more preferably 2 to 50%, and particularly preferably 10 to 30%. If the oxygen concentration is less than 1%, the reaction between the hydroxyl group in the pyrene skeleton and the hydrogen atom may not occur sufficiently. On the other hand, if it exceeds 70%, the oxidation reaction proceeds excessively and the lower layer film may be decomposed.

[3] Pattern formation method:
The pattern forming method of the present invention includes (1) a step of applying a resist composition on a resist underlayer film formed by the method of forming a resist underlayer film of the present invention to form a resist film, and the resulting resist film , Selectively irradiating radiation to expose the resist film (2), developing the exposed resist film to form a resist pattern (3), and using the resist pattern as a mask, (4) forming a predetermined pattern on the substrate to be processed by dry etching the film and the substrate to be processed.

According to such a process, the resist pattern can be transferred to the substrate to be processed with high reproducibility. Therefore, it can be particularly preferably used in a pattern forming method using a multilayer resist process in a region finer than 90 nm (ArF, ArF in immersion exposure, F ₂ , EUV, nanoimprint) among multilayer resist processes. .

[3-1] (1) Step:
The step (1) is a step of forming a resist film by applying a resist composition on the resist underlayer film formed by the method for forming a resist underlayer film of the present invention.

  Examples of the resist composition include a positive or negative chemically amplified resist composition containing a photoacid generator, a positive resist composition comprising an alkali-soluble resin and a quinonediazide-based photosensitizer, and an alkali-soluble resin and a crosslink And negative resist compositions comprising an agent.

  The solid content concentration of the resist composition is preferably, for example, 5 to 50% by mass. Moreover, as a resist composition, it is preferable to use what was filtered with the filter of the hole diameter of about 0.2 micrometer. In addition, the pattern formation method of this invention can also use a commercially available resist composition as a resist composition as it is.

  Examples of the method for applying the resist composition include conventional methods such as a spin coating method. The application amount of the resist composition is adjusted so that a resist film having a predetermined film thickness is obtained.

  The resist film can be formed by volatilizing the solvent in the coating film (that is, the solvent contained in the resist composition) by pre-baking the coating film of the resist composition. Although the temperature at the time of prebaking can be suitably set according to the kind etc. of resist composition to be used, it is preferable that it is 30-200 degreeC, and it is still more preferable that it is 50-150 degreeC.

  In the pattern forming method of the present invention, in this step, if necessary, an intermediate layer may be further formed on the resist underlayer film, and a resist film may be formed on the intermediate layer. This intermediate layer is a layer having a predetermined function required to further supplement the functions of the lower layer film and / or the resist film in forming a resist pattern or to obtain functions that these layers do not have. For example, when the antireflection film is formed as an intermediate layer, the antireflection function of the lower layer film can be further supplemented.

  This intermediate layer can be formed using an organic compound or an inorganic oxide. Examples of the organic compound include commercially available materials such as “DUV-42”, “DUV-44”, “ARC-28”, and “ARC-29” manufactured by Brewer Science. Alternatively, materials commercially available under trade names such as “AR-3” and “AR-19” manufactured by Rohm and Haas can be used. Examples of the inorganic oxide include materials commercially available under trade names such as “NFC SOG01” and “NFC SOG04” manufactured by JSR, polysiloxane formed by CVD, titanium oxide, alumina oxide, and oxide. Tungsten or the like can be used.

  Examples of the method for forming the intermediate layer include a coating method and a CVD method. Among these, a coating method is preferable. When the coating method is used, there is an advantage that the intermediate layer can be continuously formed after the lower layer film is formed.

  The film thickness of the intermediate layer can be appropriately selected according to the function required for the intermediate layer. For example, in a general lithography process, it is preferably 10 to 3000 nm, and preferably 20 to 300 nm. More preferably. If the film thickness of the intermediate layer is less than 10 nm, the intermediate layer may be scraped and lost during the etching process of the lower layer film. On the other hand, if it exceeds 3000 nm, there is a possibility that the processing conversion difference becomes large when the resist pattern is transferred to the intermediate layer.

[3-2] Step (2):
The step (2) is a step of exposing the resist film by selectively irradiating the obtained resist film with radiation. Here, “selectively” specifically means through a photomask on which a predetermined mask pattern is formed.

Irradiation can be appropriately selected according to the type of acid generator used in the resist composition. For example, visible light, ultraviolet light, far ultraviolet light, X-rays, electron beams, gamma rays, molecules A line, an ion beam, etc. can be mentioned. Among these, far ultraviolet rays are preferable, and in particular, KrF excimer laser (248 nm), ArF excimer laser (193 nm), F ₂ excimer laser (wavelength 157 nm), Kr ₂ excimer laser (wavelength 147 nm), ArKr excimer laser (wavelength 134 nm). Extreme ultraviolet rays (wavelength 13 nm, etc.) are more preferable.

[3-3] (3) Step:
(3) The step is a step of developing the exposed resist film to form a resist pattern.

  The developer used for development can be appropriately selected according to the type of resist composition used. For example, when using a positive chemically amplified resist composition or a positive resist composition containing an alkali-soluble resin, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine , N-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, dimethylethanolamine, triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo Alkaline aqueous solutions such as [5.4.0] -7-undecene and 1,5-diazabicyclo [4.3.0] -5-nonene can be used. These alkaline aqueous solutions may be those obtained by adding an appropriate amount of a water-soluble organic solvent, for example, an alcohol such as methanol or ethanol, or a surfactant.

  Further, when using a negative chemically amplified resist composition or a negative resist composition containing an alkali-soluble resin, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, aqueous ammonia, etc. Inorganic alkalis, primary amines such as ethylamine and n-propylamine, secondary amines such as diethylamine and di-n-butylamine, tertiary amines such as triethylamine and methyldiethylamine, dimethylethanolamine and triethanolamine Alcohol amines such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, choline and other quaternary ammonium salts, and alkaline aqueous solutions such as pyrrole and piperidine cyclic amines can be used.

  In this step, after developing with the developer, it can be washed and dried. In order to improve resolution, pattern profile, developability, etc., it is preferable to perform post-baking before developing the resist film. The post-baking temperature can be appropriately adjusted according to the type of resist composition used, but is preferably 50 to 200 ° C, more preferably 80 to 150 ° C.

[3-4] (4) Step:
Step (4) is a step of forming a predetermined pattern on the substrate to be processed by dry etching the resist underlayer film and the substrate to be processed using the resist pattern as a mask. When the intermediate layer is formed on the resist underlayer film, the intermediate layer is also dry etched together with the resist underlayer film and the substrate to be processed.

A conventionally known dry etching apparatus can be used for the dry etching. The source gas at the time of dry etching is appropriately selected according to the elemental composition of the film to be etched, but includes an oxygen atom gas such as O ₂ , CO, CO ₂ , an inert gas such as He, N ₂ , Ar, A chlorine-based gas such as Cl ₂ or BCl ₄ , a gas of H ₂ or NH ₄ , or the like can be used. In addition, these gases can also be mixed and used.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example and a comparative example, this invention is not limited to these Examples and a comparative example. In the description of Examples, “parts” and “%” are based on mass unless otherwise specified.

[Weight average molecular weight (Mw)]
The weight average molecular weight (Mw) and the number average molecular weight (Mn) of the polymer obtained in each of the following synthesis examples were measured using flow rate: Measurement was performed by a gel permeation chromatograph (detector: differential refractometer) using monodisperse polystyrene as a standard under the analysis conditions of 1.0 ml / min, elution solvent: tetrahydrofuran, and column temperature: 40 ° C.

(Synthesis Example 1)
A separable flask equipped with a thermometer was charged with 100 parts of 1,6-dihydroxypyrene, 30 parts of formalin, 1 part of p-toluenesulfonic acid, and 150 parts of propylene glycol monomethyl ether in a nitrogen atmosphere while stirring. Polymerization was performed at 80 ° C. for 6 hours to obtain a reaction solution. Thereafter, the reaction solution was diluted with 100 parts of n-butyl acetate, and the organic layer was washed with a large amount of a mixed solvent of water / methanol (mass ratio: 1/2). Thereafter, the solvent was distilled off to obtain a polymer (A-1). The weight average molecular weight (Mw) of the obtained polymer (A-1) was 1200. The results are shown in Table 1.

(Synthesis Examples 2 to 5, Comparative Synthesis Example 1)
Polymers (A-2) to (A-5) and (AR-1) were obtained in the same manner as in Synthesis Example 1 except that the monomers shown in Table 1 were used. Table 1 shows the weight average molecular weights (Mw) of the obtained polymers (A-2) to (A-5) and (AR-1).

( Comparative Reference Example 1)
In a separable flask equipped with a reflux tube, 8-methyl-8-t-butoxycarbonylmethoxycarbonyltetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] dodec-3-ene (hereinafter referred to as monomer (I)) 29 parts, 8-methyl-8-hydroxytetracyclo [6.2.1.1 ^3,6 . 0 ^2,7 ] dodec-3-ene (hereinafter referred to as “monomer (II)”) 10 parts, maleic anhydride (hereinafter referred to as “monomer (III)”) 18 parts, 2,5-dimethyl Charge 4 parts of -2,5-hexanediol diacrylate, 1 part of t-dodecyl mercaptan, 4 parts of azobisisobutyronitrile, and 60 parts of 1,2-diethoxyethane and stir at 70 ° C. for 6 hours. Polymerization was performed to obtain a reaction solution.

  Thereafter, the obtained reaction solution was poured into a large amount of a mixed solvent of n-hexane / i-propyl alcohol (mass ratio: 1/1) to solidify the resin in the reaction solution. The coagulated resin is washed several times with the above mixed solvent and then vacuum-dried, and the structure represented by the following formula (a), the structure represented by the following formula (b), and the following formula (c) A resin having the structure shown was obtained (yield 60%). In this resin, the molar ratio of the structure represented by the following formula (a), the structure represented by the following formula (b), and the structure represented by the following formula (c) is 64:18:18. And the weight average molecular weight (Mw) was 27,000.

  80 parts of the resin obtained, 1.5 parts of 1- (4-methoxynaphthalen-1-yl) tetrahydrothiophenium nonafluoro-n-butanesulfonate, and 0.04 part of tri-n-octylamine are propylene. It was dissolved in 533 parts of glycol monomethyl ether acetate to obtain a resist composition.

( Reference Example 1)
10 parts of the polymer (A-1) obtained in Synthesis Example 1, 0.5 part of tetramethoxymethylglycoluril as a crosslinking agent, and bis (4-t-butylphenyl) iodonium nonafluoro-n-butane as an acid generator 0.5 part of sulfonate was dissolved in 89 parts of a solvent (ethyl lactate) to obtain a mixed solution. Thereafter, the mixed solution was filtered through a membrane filter having a pore size of 0.1 μm to obtain a resist underlayer film forming composition. Using this resist underlayer film forming composition as a coating solution, various evaluations shown below were performed.

(1) Formation of ArF positive resist pattern:
First, a resist underlayer film forming composition was applied on a silicon wafer having a diameter of 8 inches by spin coating. Next, it was placed on a hot plate and heated at 180 ° C. for 60 seconds. Then, it heated at 350 degreeC for 60 second, and formed the 0.3-micrometer-thick lower layer film. Next, an intermediate layer composition solution for a three-layer resist process (trade name “NFC SOG080”, manufactured by JSR Corporation) was spin-coated on this lower layer film, placed on a hot plate, and heated at 200 ° C. for 60 seconds. Subsequently, an intermediate layer film having a thickness of 0.05 μm was formed by heating at 300 ° C. for 60 seconds. Next, the resist composition obtained in Comparative Reference Example 1 was spin-coated on the intermediate layer film, and pre-baked on a hot plate at 130 ° C. for 90 seconds to form a resist film having a thickness of 0.2 μm. .

  Next, using an ArF excimer laser exposure apparatus (lens numerical aperture of 0.78, exposure wavelength of 193 nm) manufactured by NIKON, exposure was performed for an optimal exposure time through a mask pattern. Next, after post-baking on a hot plate at 130 ° C. for 90 seconds, the resist film was developed at 25 ° C. for 1 minute using a 2.38 mass% aqueous tetramethylammonium hydroxide solution. Thereafter, it was washed with water and dried to obtain a resist film on which a positive resist pattern was formed.

  Then, the resist film on which the positive resist pattern was formed was observed with a scanning electron microscope and evaluated according to the following criteria (referred to as “pattern shape” in Table 2). The case where the observed pattern shape is a rectangle is good (denoted as “◯” in Table 2), and the shape other than the rectangle (for example, T-top, scum, etc.) is defective (denoted as “X” in Table 2). It was.

(2) Standing wave prevention effect:
The presence or absence of the influence of standing waves on the resist film on which the positive resist pattern was formed was observed with a scanning electron microscope and evaluated according to the following criteria. When the standing wave due to reflection from the lower layer film is not seen on the side of the pattern, it is judged as good (denoted as “◯” in Table 2), and when standing wave is seen as bad (in Table 2, “ X ”).

(3) Optical characteristics:
A resist underlayer film forming composition was spin-coated on a silicon wafer having a diameter of 8 inches. Then, it heated at 300 degreeC for 120 second on the hotplate, and formed the lower layer film with a film thickness of 0.3 micrometer. About this lower layer film, J. Org. A. Using a “spectral ellipsometer VUV-VASE” manufactured by WOOLLAM, the refractive index (shown as “refractive index (n)” in Table 1) and the absorbance (in Table 1, “extinction coefficient (k)”) Measured).

(4) Etching resistance:
First, a resist underlayer film forming composition was spin coated on a silicon wafer having a diameter of 8 inches by spin coating to form an underlayer film having a thickness of 300 nm. Thereafter, this lower layer film was subjected to an etching process (pressure: 0.03 Torr, high frequency power: 3000 W, Ar / CF4 = 40/100 sccm, substrate temperature: 20 ° C.), and the thickness of the lower layer film after the etching process was measured. Then, the etching rate (nm / min) was calculated from the relationship between the reduction amount of the film thickness and the processing time, and the value was used as the evaluation of etching resistance (shown as “etching resistance” in Table 2).

  If the refractive index is in the range of 1.40 to 1.60, it can be determined that the ArF exposure resist process has a sufficient function as an antireflection film. If the extinction coefficient (k) is in the range of 0.25 to 0.40, it can be determined that the ArF exposure resist process has a sufficient function as an antireflection film.

(5) Embeddability in vias:
Evaluation was made as to whether or not the obtained composition for forming a resist underlayer film satisfactorily penetrates into a via hole, that is, whether or not the resist underlayer film formation was satisfactorily embedded in the via hole. First, a resist underlayer film forming composition was spin-coated on a tetraethylorthosilicate (TEOS) substrate on which via holes having a via size of 100 nm, a via pitch of 1H / 1.2S, and a depth of 1000 nm were formed. After spin coating, it was heated on a hot plate at 180 ° C. for 60 seconds, and then further heated at 250 ° C. for 60 seconds. In this manner, the composition for forming a resist underlayer film was embedded in the via hole, and an underlayer film having a thickness of 300 nm was formed on the TEOS surface. Thereafter, via holes were observed with a scanning electron microscope and evaluated according to the following criteria (shown as “via embedding property” in Table 2). When the composition for forming the resist underlayer film penetrates into the via hole (when embedded), it is judged as good (“○”), and when not penetrated (when not buried), it is defective (“×”). ).

In the composition for forming a resist underlayer film of this reference example , the evaluation of the formation of a positive resist pattern for ArF is “◯”, the evaluation of the standing wave prevention effect is “◯”, and the refractive index (n) is It was 1.51, the extinction coefficient (k) was 0.44, the etching rate (nm / min) was 0.68, and the evaluation of embeddability in vias was “◯”. The evaluation results are shown in Table 2.

(Examples 2 and 3, Reference Examples 1, 4, and 5, Comparative Example 1)
A resist underlayer film forming composition was prepared in the same manner as in Reference Example 1 except that the polymers shown in Table 2 (Polymers (A-2) to (A-5) and (AR-1)) were used. The obtained resist underlayer film forming composition was evaluated in the same manner as in Reference Example 1. The evaluation results are shown in Table 2.

As is apparent from Table 2, the resist underlayer film forming compositions of Examples 2 and 3 are superior in etching resistance to the resist underlayer film forming composition of Comparative Example 1, and are not easily bent in the dry etching process. It was confirmed that a lower layer film capable of transferring the resist pattern to the substrate to be processed with high reproducibility can be formed.

  The composition for forming a resist underlayer film according to the present invention is suitable as a material for forming an underlayer film used in a multi-layer resist process suitable for microfabrication in a lithography process, particularly for manufacturing a highly integrated circuit element.

  The method for forming a resist underlayer film according to the present invention can be employed as a method for forming an underlayer film used in a multi-layer resist process suitable for microfabrication in a lithography process, particularly for manufacturing a highly integrated circuit element.

  The pattern formation method of the present invention is suitable as a pattern formation method in a multilayer resist process suitable for microfabrication in a lithography process, particularly for manufacturing a highly integrated circuit element.

Claims (6)

Containing a novolak resin and an organic solvent containing a pyrene skeleton having a hydroxyl group,
The composition for forming a resist underlayer film , wherein the novolac resin further comprises a naphthalene skeleton having two or more phenolic hydroxyl groups . The resist underlayer film forming composition according to claim 1, wherein the pyrene skeleton is derived from dihydroxypyrene. The composition for forming a resist underlayer film according to claim 1 or 2 , further comprising at least one of an acid generator and a crosslinking agent. A resist underlayer film forming composition according to any one of claims 1 to 3 is applied on a substrate to be processed to form a coating film, and the formed coating film is baked together with the substrate to be processed. A method for forming a resist underlayer film, which comprises forming a resist underlayer film on the substrate to be processed. The method for forming a resist underlayer film according to claim 4 , wherein the baking is performed in an atmosphere containing oxygen. (1) a step of applying a resist composition on the resist underlayer film formed by the method of forming a resist underlayer film according to claim 4 or 5 to form a resist film;
(2) step of selectively irradiating the obtained resist film with radiation to expose the resist film;
(3) the step of developing the exposed resist film to form a resist pattern;
(4) A step of forming a predetermined pattern on the substrate to be processed by dry etching the resist underlayer film and the substrate to be processed using the resist pattern as a mask.