WO2009119201A1 - Resist underlayer film, composition for resist underlayer film formation, and method for resist underlayer film formation - Google Patents

Abstract

Disclosed is a resist underlayer film, which has excellent etching resistance and, particularly in a dry etching process, is less likely to cause bending of an underlayer film pattern, and can realize the transfer of a resist pattern onto a substrate to be processed faithfully with good reproducibility. Also disclosed are a composition for resist underlayer film formation and a method for resist underlayer film formation. The resist underlayer film is used in a multilayer resist process comprising forming a resist underlayer film on a substrate to be processed, forming a resist pattern on the resist underlayer film, then once transferring the resist pattern onto the resist underlayer film to form an underlayer film pattern, and then performing transfer onto the substrate to be processed, using the underlayer film pattern as an etching mask. The content of a hydrogen atom in the resist underlayer film is 20 to 30 atomic%.

Description

Resist underlayer film, resist underlayer film forming composition, and resist underlayer film forming method

The present invention relates to a resist underlayer film, a resist underlayer film forming composition, and a resist underlayer film forming method. More specifically, the present invention can be suitably used for microfabrication in a lithography process using various types of radiation (particularly, a multilayer resist process suitable for manufacturing a highly integrated circuit element), and has excellent etching resistance. The present invention relates to a resist underlayer film, a resist underlayer film forming composition, and a resist underlayer film forming method capable of transferring a resist pattern to a substrate to be processed faithfully with high reproducibility in an etching process.

The semiconductor device manufacturing process includes many steps of depositing a plurality of substances as a film to be processed on a silicon wafer and patterning the same into a desired pattern. In patterning a 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 portion or the unexposed portion of the resist film is removed by development processing to form a resist pattern, and the processed film is dry-etched using the resist pattern as an etching mask.

In such a process, ultraviolet light such as an ArF excimer laser is used as an exposure light source for exposing the resist film. Currently, there is an increasing demand for miniaturization of large-scale integrated circuits (LSIs), and the required resolution may be less than the wavelength of exposure light. As described above, when the resolution is less than the wavelength of the exposure light, the exposure process tolerance such as the exposure tolerance and the focus tolerance is insufficient. In order to make up for such a shortage of exposure process tolerance, it is effective to improve the resolution by reducing the thickness of the resist film. On the other hand, the resist thickness required for etching the film to be processed It becomes difficult to ensure.
For this reason, a resist underlayer film (hereinafter also simply referred to as “underlayer film”) is formed on the film to be processed, and the resist pattern is once transferred to the underlayer film to form the underlayer film pattern. Studies have been conducted on a process of transferring an underlayer film pattern to a film to be processed using an etching mask (hereinafter, also simply referred to as “multilayer resist process”). In such a multilayer resist process, the lower layer film is preferably made of a material having etching resistance. Examples of the material for forming such a lower layer film include, for example, a resin containing a benzene ring that absorbs energy during etching and is known to have etching resistance, in particular, a composition containing a thermosetting phenol novolac, and acenaphthylene. A composition containing a polymer having a skeleton has been proposed (see, for example, Patent Documents 1 and 2).

JP 2001-40293 A JP 2000-143937 A

However, with further miniaturization of the etching pattern, over-etching of the resist underlayer film becomes a big problem, and further improvement in etching resistance is required.
As the etching pattern is further miniaturized, the aspect ratio of the lower layer film pattern (the ratio of the pattern width (line width) to the film thickness of the lower layer film pattern) is increased, and the lower layer film pattern is changed during etching of the substrate to be processed. There was also a problem of bending. For example, since the composition described in Patent Document 1 has low bending resistance as an underlayer film pattern, the underlayer film pattern is bent during etching of the substrate to be processed, and the resist pattern is faithfully transferred to the substrate to be processed. I could not.

The present invention has been made in view of the above-mentioned problems of the prior art, and can be suitably used for microfabrication in a lithography process using various types of radiation, has excellent etching resistance, and particularly dry etching. Provided are a resist underlayer film, a resist underlayer film forming composition, and a resist underlayer film forming method capable of transferring a resist pattern to a substrate to be processed faithfully with high reproducibility.

As a result of intensive studies, the present inventors have found that when the hydrogen content in the resist underlayer film is within a specific range (particularly 30 atom% or less), the underlayer film pattern during etching of the substrate to be processed is the conventional resist underlayer. The present inventors have found that it is harder to bend than a film and have completed the present invention.

The present invention is as follows.
[1] A resist underlayer film is formed on a substrate to be processed, a resist pattern is formed on the resist underlayer film, the resist pattern is temporarily transferred to the resist underlayer film, and then the underlayer film pattern is formed. Is a resist underlayer film used in a multilayer resist process for transferring to a substrate to be processed using an etching mask,
A resist underlayer film, wherein the content of hydrogen atoms in the resist underlayer film is 20 to 30 atom%.
[2] A resist underlayer film forming method for forming the resist underlayer film according to [1],
A step of forming a resist underlayer film by heating a coating film obtained using a composition for forming a resist underlayer film containing a resin having a phenolic hydroxyl group and a solvent; A resist underlayer film forming method, characterized in that it is in air, a heating temperature is 300 to 550 ° C., and a heating time is 30 to 600 seconds.
[3] The resist underlayer film forming method according to [2], wherein the heating temperature is 350 to 550 ° C., and the heating time is 120 to 600 seconds.
[4] The resist underlayer film forming method according to [2] or [3], wherein the coating film is preheated at a temperature of 100 to 250 ° C. before the coating film is heated at a temperature of 300 to 550 ° C.
[5] The resin having a phenolic hydroxyl group is an aromatic compound having 6 to 10 carbon atoms having two phenolic hydroxyl groups, and at least selected from formaldehyde, paraformaldehyde, trioxane, furfural, benzaldehyde, vanillin, and naphthaldehyde. The resist underlayer film forming method according to any one of the above [2] to [4], which is a resin obtained by a condensation reaction with one kind of aldehyde derivative.
[6] The resist underlayer film forming method according to [5], wherein dihydroxynaphthalene is used as the aromatic compound having 6 to 10 carbon atoms having two phenolic hydroxyl groups.
[7] The resist underlayer film forming method according to the above [5], wherein resorcinol is used as the aromatic compound having 6 to 10 carbon atoms having two phenolic hydroxyl groups. [8] The resist underlayer film forming composition is Furthermore, the resist underlayer film forming method according to any one of [2] to [7], further comprising an accelerator.
[9] A resist underlayer film forming composition for forming the resist underlayer film according to [1],
The resist underlayer film forming composition contains a resin having a phenolic hydroxyl group and a solvent,
The resin having a phenolic hydroxyl group is obtained by a condensation reaction of dihydroxynaphthalene and at least one aldehyde derivative selected from formaldehyde, paraformaldehyde, trioxane, furfural, benzaldehyde, vanillin and naphthaldehyde. A resist underlayer film forming composition.
[10] A resist underlayer film forming composition for forming the resist underlayer film according to [1],
The resist underlayer film forming composition contains a resin having a phenolic hydroxyl group and a solvent,
The resin having a phenolic hydroxyl group is obtained by a condensation reaction between resorcinol and at least one aldehyde derivative selected from formaldehyde, paraformaldehyde, trioxane, furfural, benzaldehyde, vanillin and naphthaldehyde. A composition for forming a resist underlayer film.

The resist underlayer film of the present invention is excellent in etching resistance, and the underlayer film pattern is not easily bent when the substrate to be processed is etched. Moreover, according to the composition for forming a resist underlayer film of the present invention, the resist underlayer film can be formed. In particular, a resist underlayer film having excellent etching resistance has precise pattern transfer performance and good etching selectivity in a dry etching process, and there is little over-etching of the resist underlayer film, and a resist pattern is formed on a substrate to be processed. Transfers faithfully with good reproducibility. Furthermore, since the lower layer film pattern is not bent when the substrate to be processed is etched, an improvement in yield can be expected in microfabrication in the lithography process, particularly in the manufacture of highly integrated circuit elements. In addition, according to the resist underlayer film forming method of the present invention, the resist underlayer film forming composition is used to form an underlayer film pattern on the substrate to be processed, which has excellent etching resistance and is etched. It is possible to easily form a resist underlayer film that is not easily bent.

Hereinafter, embodiments of the present invention will be described in detail.
[1] Composition for forming resist underlayer film The composition for forming a resist underlayer film of the present invention contains a resin having a phenolic hydroxyl group (hereinafter also referred to as “resin (A)”) and a solvent.

<Resin having a phenolic hydroxyl group>
The resin (A) is obtained by a condensation reaction between an aromatic compound having 6 to 10 carbon atoms having two phenolic hydroxyl groups and an aldehyde derivative. The resin (A) may be a novolak resin obtained by reacting with an acidic catalyst or a resol resin obtained by reacting with an alkaline catalyst.

Examples of the aromatic hydrocarbon having 6 to 10 carbon atoms having two phenolic hydroxyl groups include, for example, phenols such as resorcinol and catechol; dihydroxynaphthalene (for example, 1,5-dihydroxynaphthalene, 2,7-dihydroxynaphthalene). , 2,6-dihydroxynaphthalene, 2,3-dihydroxynaphthalene) and the like. In addition, these aromatic hydrocarbons may be used individually by 1 type, and may be used in combination of 2 or more type.

As the aldehyde derivative, at least one selected from formaldehyde, paraformaldehyde, trioxane, furfural, benzaldehyde, vanillin and naphthaldehyde is used.

In the composition for forming a resist underlayer film of the present invention, as long as the hydrogen content of the resulting resist underlayer film is in the range of 20 to 30 atom%, when preparing the resin (A), Other phenolic compounds other than aromatic hydrocarbons having a phenolic hydroxyl group, other aldehyde compounds other than the above-mentioned aldehyde derivatives, and the like may be used.
Examples of the other phenol compounds include phenols such as phenol, cresol and xylenol; naphthols such as 1-naphthol and 2-naphthol. In addition, these other phenol compounds may be used individually by 1 type, and may be used in combination of 2 or more type.
Examples of the other aldehyde compounds include aldehydes such as acetaldehyde and propionaldehyde. In addition, these other aldehyde compounds may be used individually by 1 type, and may be used in combination of 2 or more type.

In the present invention, the polystyrene-equivalent weight average molecular weight (hereinafter referred to as “Mw”) of the resin (A) by gel permeation chromatography (GPC) is preferably 500 to 5000, more preferably 1000 to 3000. . If this Mw is less than 500, the in-plane uniformity of the film thickness may be impaired due to the effect of sublimation of low molecular components. On the other hand, when it exceeds 5000, when it is applied on a substrate having a pattern such as a via or a trench, the embedding property to the pattern may be impaired.

Also, the composition for forming a resist underlayer film in the present invention may contain only one kind of the resin (A), or may contain two or more kinds.

<Solvent>
The composition for forming a resist underlayer film in the present invention contains a solvent for dissolving the resin (A) (hereinafter referred to as “solvent (B)”), and is usually a liquid composition.
The solvent (B) is not particularly limited as long as it can dissolve the resin (A). For example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono Ethylene glycol monoalkyl ethers such as n-butyl ether; ethylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol mono-n-propyl ether acetate, ethylene glycol mono-n-butyl ether acetate Ether acetates; diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di-n-propyl ether Diethylene glycol dialkyl ethers such as diethylene glycol di-n-butyl ether; triethylene glycol dialkyl ethers such as triethylene glycol dimethyl ether and triethylene glycol diethyl ether; propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n -Propylene glycol monoalkyl ethers such as propyl ether and propylene glycol mono-n-butyl ether; propylene glycol dialkyl ethers such as propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol di-n-propyl ether and propylene glycol di-n-butyl ether Ethers; propylene glycol Monomethyl ether acetate, propylene glycol monomethyl Ether ether acetate, propylene glycol mono -n- propyl ether acetate, propylene glycol monoalkyl ether acetates such as propylene glycol monobutyl -n- butyl ether acetate;

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, 2- Ethyl droxy-2-methylpropionate, methyl 3-methoxy-2-methylpropionate, methyl 2-hydroxy-3-methylbutyrate, ethyl methoxyacetate, ethyl ethoxyacetate, methyl 3-methoxypropionate, 3-ethoxypropionic acid Ethyl, ethyl 3-methoxypropionate, 3-methoxypropyl acetate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutylpropionate, 3-methyl-3-methoxy Other esters such as butyl butyrate, methyl acetoacetate, methyl pyruvate, ethyl pyruvate; aromatic hydrocarbons such as toluene, xylene; methyl ethyl ketone, methyl-n-propyl ketone, methyl-n-butyl ketone, 2- Heptanone, 3-heptano Ketones such as 4-heptanone and cyclohexanone; amides such as N-methylformamide, N, N-dimethylformamide, N-methylacetamide, N, N-dimethylacetamide and N-methylpyrrolidone; lactones such as γ-butyrolactone And the like.

Among these solvents (B), propylene glycol monomethyl ether, ethylene glycol monoethyl ether acetate, ethyl lactate, n-butyl acetate, ethyl 3-ethoxypropionate, methyl 3-methoxypropionate, 2-heptanone, cyclohexanone, γ-butyrolactone is preferred.
In addition, these solvent (B) may be used individually by 1 type, and may be used in combination of 2 or more type.

The amount of the solvent (B) used is such that the solid content concentration of the resulting resist underlayer film forming composition is usually 5 to 80% by mass, preferably 5 to 40% by mass, more preferably 10 to 30% by mass. This is the range.

In addition, the composition for forming a resist underlayer film in the present invention includes, as necessary, an accelerator, an acid generator, a crosslinking agent, a binder resin, a radiation absorber, and a surfactant, as long as the initial effects are not impaired. These various additives can be blended. In particular, the composition for forming a resist underlayer film of the present invention preferably contains an accelerator.

<Accelerator>
The accelerator promotes a dehydrogenation reaction and reduces the hydrogen content of the resist underlayer film when heating the coating film obtained from the resist underlayer film forming composition in order to form the resist underlayer film. It is an auxiliary that can be used. Specific examples of the accelerator include a one-electron oxidant.
The one-electron oxidant means an oxidant that itself undergoes one electron transfer. For example, in the case of cerium (IV) ammonium nitrate, cerium ion (IV) obtains one electron and changes to cerium ion (III). In addition, radical oxidizing agents such as halogen obtain one electron and convert it to an anion. In this way, the phenomenon of oxidizing the oxide by taking one electron from the oxide (substrate, catalyst, etc.) is called one-electron oxidation, and the component that receives one electron at this time is called one-electron oxidant.

Typical examples of the one-electron oxidizing agent include (a) metal compounds, (b) peroxides, (c) diazo compounds, (d) halogens or halogen acids.
Examples of the metal compound (a) include metal compounds containing cerium, lead, silver, manganese, osmium, ruthenium, vanadium, thallium, copper, iron, bismuth, and nickel. Specifically, (a1) cerium salts (such as cerium (IV) ammonium nitrate (CAN; ammonium hexanitratocerium (IV)), cerium (IV) acetate, cerium (IV) nitrate, cerium (IV) sulfate ( For example, tetravalent cerium salt), (a2) lead tetraacetate, lead oxide such as lead (IV) oxide (eg, tetravalent lead compound), (a3) silver (I) oxide, silver (II) oxide, Silver carbonate (Fetizon reagent), silver compounds such as silver nitrate, (a4) manganese compounds such as permanganate, activated manganese dioxide, manganese (III) salts, (a5) osmium compounds such as osmium tetroxide, (a6) Ruthenium compounds such as ruthenium oxide, (a7) Vanadium compounds such as VOCl ₃ , VOF ₃ , V ₂ O ₅ , NH ₄ VO ₃ , NaVO ₃ , (a8) Tariu acetate (III), thallium compounds such as thallium (III) trifluoroacetate, thallium (III) nitrate, (a9) copper (II) acetate, copper (II) trifluoromethanesulfonate, copper (II) trifluoroborate, copper chloride (II), copper compounds such as copper (I) acetate, (a10) iron compounds such as iron (III) chloride and potassium hexacyanoferrate (III), (a11) bismuth compounds such as sodium bismuth, (a12) Examples thereof include nickel compounds such as nickel oxide. In addition, these may be used individually by 1 type and may be used in combination of 2 or more type.

Examples of the (b) peroxide include peracids such as peracetic acid and m-chloroperbenzoic acid, hydroxyperoxides such as hydrogen peroxide and t-butyl hydroperoxide, diacyl peroxide, perester, Examples include acid ketals, peroxydicarbonates, dialkyl peroxides, and peracid ketones. In addition, these may be used individually by 1 type and may be used in combination of 2 or more type.

Examples of the (c) diazo compound include 2,2'-azobisisobutyronitrile. In addition, these may be used individually by 1 type and may be used in combination of 2 or more type.

Examples of the (d) halogen or halogen acid include perhalogen acids, halogen acids, halogen acids, and hypohalous acids selected from halogens such as chlorine, bromine, and iodine, and halogens such as chlorine, bromine, and iodine. And salts thereof. Specific examples of halogen acid salts include sodium perchlorate and sodium bromate. In addition, these may be used individually by 1 type and may be used in combination of 2 or more type.

Among the one-electron oxidants, (b) peroxides and (c) diazo compounds are preferable, and in particular, m-chloroperbenzoic acid, t-butyl hydroperoxide, 2,2′-azobisisobutyronitrile. Is preferred. When these are used, there is no possibility that metal residues or the like adhere to the substrate, which is preferable.

Moreover, the resist underlayer film forming composition in the present invention may contain two or more of the accelerators. In particular, two or more one-electron oxidizing agents selected from the above (a) metal compound and (b) peroxide can be contained.

The amount of the accelerator is usually 1,000 parts by mass or less, preferably 0.01 to 500 parts by mass, and more preferably 0.1 to 100 parts by mass with respect to 100 parts by mass of the resin (A). Part.

<Acid generator>
The acid generator is a component that generates an acid upon exposure or heating. In the present invention, by containing an acid generator, a crosslinking reaction can be effectively caused between the molecular chains of each polymer at a relatively low temperature including normal temperature.
Examples of the acid generator that generates an acid upon exposure (hereinafter referred to as “photoacid generator”) include diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-n-butanesulfonate, diphenyliodonium pyrenesulfonate, and diphenyliodonium n. -Dodecylbenzenesulfonate, diphenyliodonium 10-camphorsulfonate, diphenyliodonium naphthalenesulfonate, 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-tert-butylphenyl) iodonium 10-camphorsulfonate, bis (4-tert-butylphenyl) iodonium naphthalenesulfonate, bis (4-tert-butylphenyl) iodonium hexafluoroantimonate, triphenylsulfonium trifluoromethane Sulfonate, triphenylsulfonium nonafluoro-n-butanesulfonate, triphenylsulfonium n-dodecylbenzenesulfonate, triphenylsulfonium naphthalenesulfonate, triphenylsulfonium 10-camphorsulfonate, triphenylsulfonium hexafluoroantimonate, 4-hydroxyphenyl phenyl・ Methylsulfonium p-toluenesulfonate, 4-hydroxyphenyl benzyl methyl Sulfonium 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 trisulfonate Fluoro Tansulfonate, 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) tetrahydro Thiophenium 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, -[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; 1,2-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 Tris (trifluoromethanesulfonate), nitrobenzyl-9,10-diethoxyanthracene-2-sulfonate, trifluoromethanesulfonylbicyclo [2,2,1] hept-5-ene-2,3-dicarbodiimide, N-hydroxysuccinimide Examples thereof include sulfonic acid compound photoacid generators such as trifluoromethanesulfonate and 1,8-naphthalenedicarboxylic acid imide trifluoromethanesulfonate.

Among these photoacid generators, 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-tert-butylphenyl) iodonium 10-camphorsulfonate, bis (4-tert-butylphenyl) Yl) and the like iodonium naphthalene sulfonate is preferred. In addition, these photo-acid generators may be used individually by 1 type, and may be used in combination of 2 or more type.

Examples of the acid generator that generates an acid upon heating (hereinafter referred to as “thermal acid generator”) include 2,4,4,6-tetrabromocyclohexadienone, benzoin tosylate, 2-nitrobenzyl, and the like. Tosylate, alkyl sulfonates and the like can be mentioned. In addition, these thermal acid generators may be used individually by 1 type, and may be used in combination of 2 or more type. Moreover, a photo-acid generator and a thermal acid generator can also be used together as an acid generator.

The amount of the acid generator is usually 5000 parts by mass or less, preferably 0.1 to 1000 parts by mass, more preferably 0.1 to 100 parts by mass with respect to 100 parts by mass of the resin (A). It is.

<Crosslinking agent>
The crosslinking agent is a component having an action of preventing intermixing between the obtained resist underlayer film and the resist film formed thereon, and further preventing the occurrence of cracks in the resist underlayer film.
As such a crosslinking agent, polynuclear phenols and various commercially available curing agents can be used.
Examples of the polynuclear phenols include binuclear phenols such as 4,4′-biphenyldiol, 4,4′-methylene bisphenol, 4,4′-ethylidene bisphenol, and bisphenol A; 4,4 ′, 4 ″ -Trinuclear phenols such as methylidenetrisphenol, 4,4 '-[1- [4- {1- (4-hydroxyphenyl) -1-methylethyl} phenyl] ethylidene] bisphenol; polyphenols such as novolak Is mentioned. Among these, 4,4 ′-[1- [4- {1- (4-hydroxyphenyl) -1-methylethyl} phenyl] ethylidene] bisphenol, novolak, and the like are preferable. In addition, these polynuclear phenols may be used individually by 1 type, and may be used in combination of 2 or more type.

Examples of the curing agent include 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, and the following trade names: Epicoat 812, 815, 826, 828, 834, 834 871, 1001, 1004, 1007, 1007, 1009, 1031 [above, manufactured by Yuka Shell Epoxy Co., Ltd.], Araldite 6600, 6700, 6800, 502, 6071, 6084, 6097, 6099 (above, manufactured by Ciba Geigy), DER331, 332, 333, 66 1, 644, 667 [above, manufactured by Dow Chemical Co., Ltd.]; Cymel 300, 301, 303, 350, 370, 771, 325, 327, 703, 712, Melamine-based curing agents such as 701, 272, 202, Mycoat 506, 508 [Mitsui Cyanamid Co., Ltd.]; Cymel 1123, 1123-10, 1128, Mycoat 102, 105, Benzoguanamine-based curing agents such as 106 and 130 [above, manufactured by Mitsui Cyanamid Co., Ltd.]; Cymel 1170, 1172 [above, manufactured by Mitsui Cyanamid Co., Ltd.], Nicarak N-2702 [manufactured by Sanwa Chemical Co., Ltd.] And the like, and the like. Of these, melamine curing agents, glycoluril curing agents and the like are preferable.
In addition, these hardening | curing agents may be used individually by 1 type, and may be used in combination of 2 or more type. Moreover, polynuclear phenols and a hardening | curing agent can also be used together as a crosslinking agent.

The blending amount of the crosslinking agent is usually 5000 parts by mass or less, preferably 1 to 1000 parts by mass, and more preferably 1 to 20 parts by mass with respect to 100 parts by mass of the resin (A).

<Binder resin>
As the binder resin, various thermoplastic resins and thermosetting resins can be used. The thermoplastic resin is a component having an action of imparting the fluidity and mechanical characteristics of the added thermoplastic resin to the lower layer film.
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, and poly-1-decene. Α-Olefin polymers such as 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) Α, β-unsaturated ketone polymers such as: (meth) acrylic acid, α-chloroacrylic acid, (meth) acrylic acid salt, (meth) acrylic acid Polymers of α, β-unsaturated carboxylic acids or derivatives thereof such as stealth 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; (meth) acrylonitrile such as (meth) acrylonitrile and α-chloroacrylonitrile or derivatives thereof Polymers; (meth) acrylamides such as (meth) acrylamide and N, N-dimethyl (meth) acrylamide Polymers of ruamide or derivatives thereof; polymers of styryl metal compounds; polymers of vinyloxy metal compounds; polyimines; polyphenylene oxide, poly-1,3-dioxolane, polyoxirane, polytetrahydrofuran, polytetrahydropyran, etc. 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; Polysulfones; Polyazines; Polyamines; Polyaromatic ketones; Polyimides; Polybenzimidazoles; Polybenzoxazoles; Polybenzothiazoles; Polyaminotriazoles; S; Poripirazoru like; poly-tetrazole compounds; polyquinoxaline like; poly triazine; polybenzoxazinone like; polyquinoline compounds, poly anthrahydroquinone gelsolin such like.

The thermosetting resin is a component having an action of preventing intermixing between the resist underlayer film obtained and the resist film formed thereon, which is cured by heating and becomes insoluble in a solvent.
Examples of the thermosetting resin include thermosetting acrylic resins, phenol resins, urea resins, melamine resins, amino resins, aromatic hydrocarbon resins, epoxy resins, alkyd resins, and the like. Is mentioned. Of these, urea resins, melamine resins, aromatic hydrocarbon resins and the like are preferable.

In addition, these binder resins may be used individually by 1 type, and may be used in combination of 2 or more type.
The amount of the binder resin is usually 20 parts by mass or less, preferably 1 to 10 parts by mass with respect to 100 parts by mass of the resin (A).

<Radiation absorber>
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, norbixin, stilbene, 4, Optical brighteners such as 4′-diaminostilbene derivatives, coumarin derivatives, pyrazoline derivatives; UV absorbers such as hydroxyazo dyes, trade names “Tinuvin 234” and “Tinuvin 1130” (manufactured by Ciba Geigy); anthracene derivatives And aromatic compounds such as anthraquinone derivatives. In addition, these radiation absorbers may be used individually by 1 type, and may be used in combination of 2 or more type.

The compounding amount of the radiation absorber is usually 100 parts by mass or less, preferably 1 to 50 parts by mass with respect to 100 parts by mass of the resin (A).

<Surfactant>
The surfactant is a component having an action of improving coatability, striation, wettability, developability and the like.
Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene-n-octylphenyl ether, polyoxyethylene-n-nonylphenyl ether, polyethylene glycol dilaurate , Nonionic surfactants such as polyethylene glycol distearate and the following trade names: KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), Polyflow No. 75, no. 95 [above, manufactured by Kyoeisha Yushi Chemical Co., Ltd.], F-top EF101, EF204, EF303, EF352 [above, manufactured by Tochem Products Co., Ltd.], MegaFuck F171, F172, F173 [above, Dainippon Manufactured by Ink Chemical Industry Co., Ltd.], FLORARD FC430, FC431, FC135, FC135 [above, manufactured by Sumitomo 3M], Asahi Guard AG710, Surflon S382, SC101, SC102, SC103, SC104, SC105, SC106 [above, manufactured by Asahi Glass Co., Ltd.]. In addition, these surfactants may be used individually by 1 type, and may be used in combination of 2 or more type.

The blending amount of the surfactant is usually 15 parts by mass or less, preferably 0.001 to 10 parts by mass with respect to 100 parts by mass of the resin (A).

In addition, in the resist underlayer film forming composition of the present invention, other additives such as a storage stabilizer, an antifoaming agent, and an adhesion aid can be blended in addition to the various additives described above.

[2] Resist Underlayer Film Forming Method The resist underlayer film forming method of the present invention includes a step of forming a resist underlayer film by heating a coating film obtained using the resist underlayer film forming composition. The above description can be applied as it is to the resist underlayer film forming composition.

The coating film is usually formed by applying a resist underlayer film forming composition on a substrate to be processed.
As the substrate to be processed, for example, a silicon wafer; a wafer coated with aluminum, an oxide film, or a nitride film can be used.
Moreover, the application | coating method of the composition for resist underlayer film formation to a to-be-processed substrate is not specifically limited, For example, it can implement by appropriate methods, such as spin coating, cast coating, and roll coating.

Moreover, the said coating film is heated in air | atmosphere.
Further, the heating temperature at this time is 300 to 800 ° C., preferably 300 to 700 ° C., more preferably 350 to 550 ° C. A heating temperature of 300 to 550 ° C. is preferable because the dehydrogenation reaction proceeds sufficiently.
In this case, the heating time is 30 to 1200 seconds, preferably 60 to 800 seconds, and more preferably 120 to 600 seconds.

Further, before the coating film is heated at a temperature of 300 to 550 ° C., it may be preheated at a temperature of 100 to 250 ° C.
The heating time in the preheating is not particularly limited, but is preferably 10 to 300 seconds, and more preferably 30 to 120 seconds.
By performing this preheating, the dehydrogenation reaction can be efficiently advanced by vaporizing the solvent in advance and keeping the film dense.

In the present invention, by heating the coating film, one-electron oxidation of the resin (A) in the resist underlayer film forming composition forming the coating film (for example, one electron of the phenolic hydroxyl group of the resin (A)) Oxidation) is considered to cause a dehydrogenation reaction and increase the molecular weight of the resin.

By such a method for forming a resist underlayer film, a resist underlayer film having a hydrogen content of 30 atom% or less, particularly 20 to 30 atom%, more preferably 20 to 28 atom% can be obtained.
The method for measuring the hydrogen content in the resist underlayer film is the same as in the examples described later.

In the resist underlayer film forming method of the present invention, the coating film is usually cured by heating the coating film to form a resist underlayer film. A predetermined photocuring agent is added to the resist underlayer film forming composition. By containing (crosslinking agent), the exposure process with respect to the heated coating film can be provided, photocured, and a resist underlayer film can also be formed. Depending on the type of acid generator blended in the resist underlayer film forming composition, the radiation exposed at this time is visible light, ultraviolet light, far ultraviolet light, X-ray, electron beam, γ-ray, molecular beam, It is appropriately selected from an ion beam or the like.

In the resist underlayer film forming method of the present invention, by adding a predetermined thermosetting agent and / or a photocuring agent (crosslinking agent) to the resist underlayer film forming composition, before heating the coating film, A crosslinking step by exposure and / or heating may be provided to partially crosslink the resin (A) in the coating film.

[3] Resist Underlayer Film The resist underlayer film of the present invention is formed by forming a resist underlayer film on a substrate to be processed, forming a resist pattern on the resist underlayer film, and then transferring the resist pattern once to the resist underlayer film. After the film pattern is formed, this lower layer film pattern is used as an etching mask and is used in a multilayer resist process that is transferred to a substrate to be processed.
The resist underlayer film can be formed of a resist underlayer film forming composition containing a resin having a phenolic hydroxyl group and a solvent, and has a hydrogen content of 20 to 30 atom%.
Although the resist underlayer film forming composition is not particularly limited, for example, the above-described resist underlayer film forming composition of the present invention can be used.
The resist underlayer film has a hydrogen content of 20 to 30 atom%, preferably 20 to 28 atom%. The method for measuring the hydrogen content in the resist underlayer film is the same as in the examples described later.
The method for forming the resist underlayer film is not particularly limited, and can be obtained, for example, by the above-described resist underlayer film forming method of the present invention.

[4] Pattern Forming Method As a method for forming a resist pattern using the resist underlayer film forming composition of the present invention, for example, (1) a resist underlayer film forming composition is applied on a substrate to be processed and the resist underlayer film is formed. A step of forming a film (hereinafter referred to as "step (1)"), and (2) a step of applying a resist composition on the obtained resist underlayer film to form a resist film (hereinafter referred to as "step (" 2) "), and (3) a step of exposing the resist film by selectively irradiating the resulting resist film with radiation through a photomask (hereinafter referred to as" step (3) "). ), (4) developing the exposed resist film to form a resist pattern (hereinafter referred to as “process (4)”), and (5) using the resist pattern as a mask (etching mask). And a step of forming a pattern by dry etching the bottom layer film and the substrate to be processed (hereinafter referred to as “step (5)”).
According to this pattern forming method, the resist pattern can be faithfully transferred to the substrate to be processed with high reproducibility in the dry etching process.

In the step (1), a resist underlayer film is formed on the substrate to be processed by the resist underlayer film forming method described above. For the resist underlayer film forming method, the above description can be applied as it is.
The thickness of the resist underlayer film formed in this step (1) is usually 0.1 to 5 μm.

Moreover, in this pattern formation method, after the said process (1), the process (1 ') which forms an intermediate | middle layer on a resist lower layer film may be further provided as needed.
This intermediate layer is a layer provided with these functions in order to further supplement the functions of the resist underlayer film and / or the resist film in the formation of the resist pattern, or to obtain the functions that they do not have. . For example, when the antireflection film is formed as an intermediate layer, the antireflection function of the resist underlayer film can be further supplemented.

This intermediate layer can be formed of an organic compound or an inorganic oxide. Examples of organic compounds include materials marketed under the trade names such as “DUV-42”, “DUV-44”, “ARC-28”, and “ARC-29” manufactured by Brewer Science, and Rohm and Haas. Commercially available materials such as “AR-3” and “AR-19” manufactured by the company can be used. Examples of inorganic oxides include materials marketed under the 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.

The method for forming the intermediate layer is not particularly limited, and for example, a coating method, a CVD method, or the like can be used. Among these, the coating method is preferable. When the coating method is used, the intermediate layer can be formed continuously after forming the resist underlayer film.

The film thickness of the intermediate layer is not particularly limited, and is appropriately selected according to the function required for the intermediate layer, but is preferably in the range of 10 to 3000 nm, more preferably 20 to 300 nm. When the film thickness of this intermediate layer is less than 10 nm, the intermediate layer may not be removed during the etching of the resist underlayer film. On the other hand, when the thickness exceeds 3000 nm, a difference in processing conversion occurs remarkably when the resist pattern is transferred to the intermediate layer.

In the step (2), a resist film is formed on the resist underlayer film and / or the intermediate layer using the resist composition solution.
Specifically, the resist composition solution is applied so that the resulting resist film has a predetermined film thickness, and then pre-baked to volatilize the solvent in the film and form a resist film.
Examples of the resist composition solution 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 negative resist composition composed of a crosslinking agent and the like. Further, the solid content concentration of the resist composition solution when applied on the resist underlayer film or intermediate layer is usually about 5 to 50% by mass, and is generally filtered through a filter having a pore diameter of about 0.2 μm, for example. Used. In addition, the said resist composition solution can also use a commercially available thing as it is.

The method for applying the resist composition solution is not particularly limited, and can be performed by, for example, a spin coating method.
The pre-baking temperature is appropriately adjusted according to the type of resist composition solution used and the like, but is usually about 30 to 200 ° C., preferably 50 to 150 ° C.

In the step (3), a predetermined region of the obtained resist film is irradiated with radiation through a photomask and selectively exposed.
As the radiation used for the exposure, depending on the type of acid generator used in the resist composition,
Appropriately selected from visible light, ultraviolet light, far ultraviolet light, X-ray, electron beam, γ-ray, molecular beam, ion beam, etc., but is preferably far ultraviolet light, particularly 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 light (wavelength 13 nm, etc.) are preferred.

In the step (4), a resist pattern is formed by developing the exposed resist film with a developer.
The developer is appropriately selected according to the type of resist composition used. For example, 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 [5.4.0] -7-undecene, 1,5-diazabicyclo [4.3.0] -5 An alkaline aqueous solution such as nonene is used. In addition, an appropriate amount of a water-soluble organic solvent, for example, an alcohol such as methanol or ethanol, or a surfactant can be added to these alkaline aqueous solutions.

Further, after development with the developer, washing and drying are performed to form a predetermined resist pattern.
In this step, post-baking can be performed after the exposure before development in order to improve resolution, pattern profile, developability, and the like. The post-baking temperature is appropriately adjusted according to the type of resist composition used, but is usually about 50 to 200 ° C., preferably 80 to 150 ° C.

In the step (5), the resist pattern is used as a mask, and the pattern is transferred to the intermediate layer and / or the resist underlayer film by performing dry etching of the resist underlayer film using, for example, gas plasma such as oxygen plasma. The substrate to be processed is processed.
In the pattern forming method of the present invention, a predetermined pattern for substrate processing can be formed by appropriately performing the steps (1) to (5).

Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. In the examples and comparative examples, “parts” and “%” are based on mass unless otherwise specified.

[1] Preparation of resin (A) (synthesis of resins (A-1) to (A-18))
A separable flask equipped with a thermometer was charged with 10 parts of a phenol compound shown in Table 1, 10 parts of an aldehyde compound, 10 parts of p-toluenesulfonic acid, and 40 parts of methyl isobutyl ketone, and allowed to react at 50 ° C. for 12 hours with stirring. It was. After completion of the reaction, pure water was added to the reaction solution, and washing was repeated until the aqueous layer became neutral. Thereafter, the organic layer was put into a large amount of n-heptane. Next, the precipitated solid was separated by a decantation method and washed with a large amount of n-heptane. Subsequently, the obtained resin was dried at 50 ° C. for 17 hours to obtain resins (A-1) to (A-18).
In addition, the weight average molecular weight (Mw) of each resin was measured using a “GPC column” (G2000HXL: 2, G3000HXL: 1) manufactured by Tosoh Corporation, flow rate: 1.0 ml / min, elution solvent: tetrahydrofuran, column temperature: Measurement was performed by a gel permeation chromatograph (detector: differential refractometer) using monodisperse polystyrene as a standard under analysis conditions of 40 ° C., and the results are also shown in Table 1.

[2] Preparation of resist underlayer film forming composition (for Examples) Each resin (A) and oxidation accelerator (t-butyl hydroperoxide) shown in Table 2 were mixed in a solvent (propylene glycol monomethyl ether acetate). And dissolved in the proportions shown in Table 2. Thereafter, the mixed solution was filtered through a membrane filter having a pore size of 0.1 μm to obtain resist underlayer film compositions (U-1) to (U-22).

[3] Preparation of resist underlayer film forming composition (for comparative example) Each resin (CA) and oxidation accelerator (t-butyl hydroperoxide) shown in Table 3 were mixed in a solvent (propylene glycol monomethyl ether acetate). , And dissolved at the ratio shown in Table 3. Thereafter, this mixed solution was filtered through a membrane filter having a pore size of 0.1 μm to obtain resist underlayer film compositions (UC-1) to (UC-8).

The details of the resin (CA) in Table 3 are as follows.
CA-1: acenaphthylene / hydroxymethylacenaphthylene copolymer (molar ratio; 1: 1, Mw; 1600)
CA-2: acenaphthylene / hydroxystyrene copolymer (molar ratio; 1: 1, Mw; 2300)
CA-3: Phenol / formaldehyde condensate (Mw; 1800)
CA-4: 1-naphthol / formaldehyde condensate (Mw; 1500)
CA-5: 2,7-dihydroxynaphthalene / propionaldehyde condensate (Mw; 1600)

[4] Formation of resist underlayer film (Example 1)
The resist underlayer film forming composition (U-1) is applied onto a substrate to be processed by spin coating, and baked (baked) in an air atmosphere at 350 ° C. for 120 seconds. A film was formed to obtain a substrate with a resist underlayer film (Example 1) in which a resist underlayer film was formed on a substrate to be processed.
In this embodiment, two types of processing substrates, a silicon wafer and a TEOS substrate, are used as processing substrates, a resist underlayer film is formed on each processing substrate, and two types of resist underlayer films are attached. A substrate was obtained. Further, a resist underlayer film having a thickness of 300 nm was formed on the silicon wafer, and a resist underlayer film having a thickness of 500 nm was formed on the TEOS substrate.

(Examples 2 to 22 and Comparative Examples 1 to 8)
In the same manner as in Example 1, a resist underlayer film was formed on each substrate to be processed using two types of substrates to be processed, that is, a silicon wafer and a TEOS substrate, and a substrate with a resist underlayer film (Examples 2 to 22, and Comparative Examples 1 to 8) were obtained.

[5] Performance evaluation of resist underlayer film Using the substrates with resist underlayer films of Examples 1 to 22 and Comparative Examples 1 to 8, measurement of the elemental composition (hydrogen content) of the resist underlayer film and measurement of film curability Etching resistance and bending resistance were evaluated. The results are shown in Tables 4 and 5.

<Element composition of resist underlayer film (measurement of hydrogen content)>
The content (mass%) of carbon, hydrogen, oxygen, and nitrogen of the resist underlayer film in each substrate with a resist underlayer film using a silicon wafer as the substrate to be processed is measured using an organic element analyzer (manufactured by J Science Co., Ltd. Measurement was performed using “CHN coder JM10”).
Thereafter, the number of atoms of each element contained in the film is calculated by [weight-converted value of each element (mass%) / mass of each element (g)], and then [number of hydrogen atoms in film / in film] From the total number of atoms, the hydrogen content (atom%) after the dehydrogenation reaction was determined.

<Film curability>
Each substrate with a resist underlayer film using a silicon wafer as a substrate to be processed is immersed in propyl glycol monomethyl ether acetate for 1 minute at room temperature, and the film thickness change rate of the resist underlayer film before and after the immersion is measured using a spectroscopic ellipsometer UV1280E (KLA-TENCOR The measurement was performed using The evaluation criteria were “◯” when the film thickness change rate was 0%, and “X” when the film thickness change rate exceeded 0%.

<Etching resistance>
For each substrate with a resist underlayer film using a silicon wafer as the substrate to be processed, CF ₄ / Ar / O ₂ (CF ₄ : 40 mL / min, using an etching apparatus (manufactured by Shinko Seiki Co., Ltd., model number “EXAM”), The resist underlayer film was etched at Ar: 20 mL / min, O ₂ : 5 mL / min, pressure: 20 Pa, RF power: 200 W, processing time: 40 seconds, temperature: 15 ° C.) The film thickness was measured, the etching rate was calculated, and the etching resistance was evaluated.
The etching rate was calculated by forming a reference resist underlayer film using a resist underlayer film forming composition (trade name “NFC CT08”) manufactured by JSR. The evaluation criteria were “◯” when the etching rate was less than + 10% as compared with the reference resist underlayer film, and “X” when the etching rate was + 10% or more.

<Bending resistance>
Each substrate with a resist underlayer film using a TEOS substrate as a substrate to be processed is used. On this resist underlayer film (film thickness 600 nm), an intermediate layer composition solution for a three-layer resist process (manufactured by JSR, trade name “NFC SOG080”) ) Was spin-coated and heated on a hot plate at 200 ° C. for 60 seconds and further at 300 ° C. for 60 seconds to form an intermediate layer having a thickness of 50 nm. Next, an ArF resist composition (trade name “AR1682J” manufactured by JSR Corporation) is spin-coated on this intermediate layer, and prebaked on a hot plate at 130 ° C. for 90 seconds to form a 200 nm-thick photoresist film ( Resist film) was formed.
Thereafter, exposure was performed for an optimal exposure time through a mask pattern using an ArF excimer laser exposure apparatus (lens numerical aperture 0.78, exposure wavelength 193 nm) manufactured by NIKON. Next, after post-baking on a hot plate at 130 ° C. for 90 seconds, using an aqueous solution of tetramethylammonium hydroxide having a concentration of 2.38%, developing at 25 ° C. for 1 minute, washing with water and drying, a positive type for ArF A resist pattern was formed.
Next, the formed resist pattern is transferred to an intermediate layer using a dry etching method to form an intermediate layer pattern. Using this intermediate layer pattern as a mask, the pattern is transferred to the resist underlayer using a dry etching method. Then, a resist underlayer film pattern was formed on the resist underlayer film. Further, using this resist underlayer film pattern as a mask, a pattern was formed on the TEOS substrate to a depth of 300 nm with CF ₄ / Ar / O ₂ .
And in order to evaluate bending tolerance, the lower layer film pattern shape was observed with the scanning electron microscope, and bending tolerance was evaluated. The evaluation criteria were “◯” when the lower layer film pattern was not bent and “X” when the lower layer film pattern was bent.

[6] Effects of Examples As shown in Table 4, in Examples 1 to 22, film curability, bending resistance, and etching resistance were all “◯”. On the other hand, as shown in Table 5, in Comparative Examples 1 to 8, the bending resistance was not “◯”.
The following reasons can be considered as a cause of obtaining such a result.
Since the resist underlayer film of the example has a hydrogen content of 30 atom% or less, it is considered that the resist underlayer film of the example had bending resistance.
Further, since Comparative Examples 1 to 7 have only one phenolic hydroxyl group, the hydrogen content in the resist underlayer film is increased, and as a result, the bending resistance is estimated to be “x”. . In Comparative Example 8, the hydrogen content of the aldehyde compound is large despite having two phenolic hydroxyl groups, so the hydrogen content in the resist underlayer film exceeds 30 atom%, resulting in bending resistance. It is presumed that it became “x”.

From the above, the resist underlayer formed by the resist underlayer film forming composition containing a resin obtained by a condensation reaction of an aromatic compound having 2 or more phenolic hydroxyl groups and having 6 to 10 carbon atoms and an aldehyde compound It was confirmed that the film had good film curability, etching resistance, and bending resistance.

According to the resist underlayer film forming composition of the present invention, it is possible to form a resist underlayer film that has excellent etching resistance and does not bend the underlayer film pattern when the substrate to be processed is etched. Therefore, it can be used very suitably for fine processing in a lithography process. In particular, in a dry etching process, it has precise pattern transfer performance and good etching selectivity, and there is little over-etching of the resist underlayer film, and the resist pattern can be faithfully transferred to the substrate to be processed with good reproducibility. . In addition, since the lower layer film pattern is not bent when the substrate to be processed is etched, an improvement in yield can be expected in microfabrication in the lithography process, particularly in the manufacture of highly integrated circuit elements.
The resist underlayer film forming method of the present invention is extremely useful as a lithography process, particularly as a process for manufacturing highly integrated circuit elements.

The present invention is not limited to the specific examples described above, and various modifications can be made within the scope of the present invention depending on the purpose and application.
Moreover, in this invention, the following resist underlayer film, the composition for resist underlayer film formation, and the resist underlayer film forming method can be mentioned as reference invention.
[1] A resist underlayer film formed from a composition for forming a resist underlayer film containing a resin having a phenolic hydroxyl group and a solvent, and having a hydrogen content of 20 to 30 atom%.
[2] A resist underlayer film forming composition comprising a resin having a phenolic hydroxyl group and a solvent,
The resin having a phenolic hydroxyl group is an aromatic compound having 6 to 10 carbon atoms having two phenolic hydroxyl groups and at least one selected from formaldehyde, paraformaldehyde, trioxane, furfural, benzaldehyde, vanillin and naphthaldehyde. A composition for forming a resist underlayer film, which is obtained by a condensation reaction with an aldehyde derivative.
[3] The method includes a step of forming a resist underlayer film by heating a coating film obtained using the composition for forming a resist underlayer film according to [2], wherein the heating atmosphere is in the air, A resist underlayer film forming method, wherein the heating temperature is 300 to 550 ° C. and the heating time is 30 to 600 seconds.

Claims (10)

1. A resist underlayer film is formed on a substrate to be processed, a resist pattern is formed on the resist underlayer film, the resist pattern is once transferred to the resist underlayer film, and then the underlayer film pattern is formed. It is a resist underlayer film used in a multilayer resist process that is used as a transfer to a substrate to be processed,
   A resist underlayer film, wherein the content of hydrogen atoms in the resist underlayer film is 20 to 30 atom%.
2. A resist underlayer film forming method for forming the resist underlayer film according to claim 1,
   A step of forming a resist underlayer film by heating a coating film obtained using a composition for forming a resist underlayer film containing a resin having a phenolic hydroxyl group and a solvent; A resist underlayer film forming method, characterized in that it is in air, a heating temperature is 300 to 550 ° C., and a heating time is 30 to 600 seconds.
3. 3. The resist underlayer film forming method according to claim 2, wherein the heating temperature is 350 to 550 ° C. and the heating time is 120 to 600 seconds.
4. 4. The resist underlayer film forming method according to claim 2, wherein the coating film is preheated at a temperature of 100 to 250 ° C. before the coating film is heated at a temperature of 300 to 550 ° C.
5. The resin having a phenolic hydroxyl group is an aromatic compound having 6 to 10 carbon atoms having two phenolic hydroxyl groups, and at least one selected from formaldehyde, paraformaldehyde, trioxane, furfural, benzaldehyde, vanillin and naphthaldehyde. The method for forming a resist underlayer film according to any one of claims 2 to 4, which is a resin obtained by a condensation reaction with an aldehyde derivative.
6. 6. The resist underlayer film forming method according to claim 5, wherein dihydroxynaphthalene is used as the aromatic compound having 6 to 10 carbon atoms having two phenolic hydroxyl groups.
7. 6. The resist underlayer film forming method according to claim 5, wherein resorcinol is used as the aromatic compound having 6 to 10 carbon atoms having two phenolic hydroxyl groups.
8. The method for forming a resist underlayer film according to any one of claims 2 to 7, wherein the composition for forming a resist underlayer film further contains an accelerator.
9. A resist underlayer film forming composition for forming the resist underlayer film according to claim 1,
   The resist underlayer film forming composition contains a resin having a phenolic hydroxyl group and a solvent,
   The resin having a phenolic hydroxyl group is obtained by a condensation reaction of dihydroxynaphthalene and at least one aldehyde derivative selected from formaldehyde, paraformaldehyde, trioxane, furfural, benzaldehyde, vanillin and naphthaldehyde. A resist underlayer film forming composition.
10. A resist underlayer film forming composition for forming the resist underlayer film according to claim 1,
    The resist underlayer film forming composition contains a resin having a phenolic hydroxyl group and a solvent,
    The resin having a phenolic hydroxyl group is obtained by a condensation reaction between resorcinol and at least one aldehyde derivative selected from formaldehyde, paraformaldehyde, trioxane, furfural, benzaldehyde, vanillin and naphthaldehyde. A composition for forming a resist underlayer film.