JP6327481B2 - Resist underlayer film forming composition - Google Patents

Description

The present invention relates to a resist underlayer film forming composition for a lithography process. In particular, the present invention relates to a composition for forming a resist underlayer film that has high hardness and is less likely to cause wiggling of a resist pattern formed by a lithography process.

In manufacturing a semiconductor device, fine processing is performed by a lithography process. In the lithography process, when the resist layer on the substrate is exposed with an ultraviolet laser such as a KrF excimer laser or an ArF excimer laser, the desired effect is caused by the standing wave generated by the reflection of the ultraviolet laser on the substrate surface. There is a known problem that a resist pattern having a shape is not formed. In order to solve the problem, it is adopted to provide a resist underlayer film (antireflection film) between the substrate and the resist layer. And it is known to use a novolak resin as a composition for forming a resist underlayer film. For example, Patent Document 1 and Patent Document 2 disclose a photoresist underlayer film forming material containing a resin having a repeating unit obtained by novolakizing a compound having a bisphenol group. Furthermore, Patent Document 3 discloses a spin-coatable antireflection film composition containing a polymer having an aromatic ring condensed in three or more in the main chain of the polymer.

In addition, a lithography process is also known in which at least two resist underlayer films are formed and used as a mask material in order to reduce the thickness of the resist layer required in accordance with the miniaturization of the resist pattern. Examples of the material forming the at least two layers include organic resins (for example, acrylic resins and novolac resins), silicon resins (for example, organopolysiloxane), and inorganic silicon compounds (for example, SiON, SiO ₂ ). When dry etching is performed using a pattern formed from the organic resin layer as a mask, the pattern needs to have etching resistance to an etching gas (for example, fluorocarbon). As a composition for forming such an organic resin layer, for example, Patent Document 4 discloses a composition containing a polymer containing a heterocyclic aromatic moiety.

JP 2006-259249 A JP 2007-316282 A Special table 2010-528334 gazette JP 2007-017976 A

By the way, when forming a resist pattern on a substrate to be processed through the above-described lithography process and etching process, there is a problem that irregular pattern bending tends to occur as the formed pattern width becomes narrower. . Specifically, in a resist underlayer film that is used as a mask material when etching a target processed substrate, a phenomenon that a pattern formed from an organic resin layer, in particular, bends left and right occurs. .

（式中、Ｘ^１は、ハロゲノ基、ニトロ基、アミノ基又はヒドロキシ基で置換されていてもよい芳香環を少なくとも１つ有する炭素原子数６乃至２０の二価の有機基を表し、Ｘ^２は、ハロゲノ基、ニトロ基、アミノ基又はヒドロキシ基で置換されていてもよい芳香環を少なくとも１つ有する炭素原子数６乃至２０の有機基、又はメトキシ基を表す。）
で表される構造単位を有するポリマー及び溶剤を含むレジスト下層膜形成組成物である。The present invention solves the above problems. That is, the present invention provides the following formula (1):

(Wherein X ¹ represents a divalent organic group having 6 to 20 carbon atoms having at least one aromatic ring optionally substituted with a halogeno group, a nitro group, an amino group or a hydroxy group, and X ² Represents an organic group having 6 to 20 carbon atoms having at least one aromatic ring optionally substituted with a halogeno group, a nitro group, an amino group or a hydroxy group, or a methoxy group.
It is a resist underlayer film forming composition containing the polymer which has a structural unit represented, and a solvent.

Examples of the halogeno group described above and below will include a chloro group and a bromo group. Examples of the divalent organic group having 6 to 20 carbon atoms having at least one aromatic ring described above and below will be, for example, a phenylene group, biphenylylene group, terphenylylene group, fluorenylene group, naphthylene group, anthrylene group, pyrenylene group (the following formula ( a-1) and a group represented by the following formula (a-2)), a carbazolylene group (a group represented by the following formula (b)) and a group represented by the following formula (c) (wherein n represents Represents 0 or 1.). Examples of the organic group having 6 to 20 carbon atoms having at least one aromatic ring include a phenyl group, a biphenylyl group, a terphenylyl group, a fluorenyl group, a naphthyl group, an anthryl group, a pyrenyl group, a carbazolyl group, and the following formula (d-1 ) And a group represented by the following formula (d-2) (wherein n represents 0 or 1).

（式中、Ｘ^１はハロゲノ基、ニトロ基、アミノ基又はヒドロキシ基で置換されていてもよい芳香環を少なくとも１つ有する炭素原子数６乃至２０の二価の有機基を表し、Ｒ^３はフェニル基、ナフチル基、アントリル基、ピレニル基、チエニル基又はピリジル基を表し、Ｒ^４は水素原子、フェニル基又はナフチル基を表し、Ｒ^３及びＲ^４がそれぞれフェニル基を表すときＲ^３及びＲ^４はそれらが結合する同一の炭素原子と一緒になってフルオレン環を形成してもよい。）
で表される構造単位を有してもよい。The polymer is further represented by the following formula (2):

(Wherein X ¹ represents a C 6-20 divalent organic group having at least one aromatic ring optionally substituted with a halogeno group, a nitro group, an amino group, or a hydroxy group, and R ³ represents A phenyl group, a naphthyl group, an anthryl group, a pyrenyl group, a thienyl group or a pyridyl group; R ⁴ represents a hydrogen atom, a phenyl group or a naphthyl group; and R ³ and R ⁴ each represent a phenyl group, R ³ and R ⁴ may form a fluorene ring together with the same carbon atom to which they are attached.
You may have a structural unit represented by these.

The resist underlayer film forming composition of the present invention may further contain at least one of a crosslinking agent, an acidic compound, a thermal acid generator and a surfactant as an optional component.

The resist underlayer film formed by using the resist underlayer film forming composition of the present invention has high hardness, and by applying the resist underlayer film, the bending of the pattern formed in the lithography process is suppressed. can do.

Examples of the structural unit of the polymer having the structural unit represented by the above formula (1) contained in the resist underlayer film forming composition of the present invention are represented by the following formulas (1-1) to (1-10). Structural units.

Furthermore, examples of the structural unit represented by the above formula (2) include a structural unit represented by the following formula (2-1).

The weight average molecular weight of the polymer contained in the resist underlayer film forming composition of the present invention is, for example, 2,000 to 10,000 in terms of standard polystyrene.

The polymer polymerizes a biphenol compound having two hydroxyphenyl groups, an aromatic compound or a heterocyclic compound, and if necessary, an aromatic aldehyde or an aromatic ketone in the presence of an acid catalyst such as a sulfonic acid compound. It can be synthesized by reaction. Examples of the biphenol compound having two hydroxyphenyl groups used for the synthesis of the polymer include 3,3 ', 5,5'-tetramethoxymethyl-4,4'-dihydroxybiphenyl. Examples of the aromatic compound used for the synthesis of the polymer include benzene, naphthalene, anthracene, pyrene, fluorene, and m-terphenyl. Examples of the heterocyclic compound used for the synthesis of the polymer include carbazole. Examples of the aromatic aldehyde used for the synthesis of the polymer include furfural, pyridinecarboxaldehyde, benzaldehyde, naphthylaldehyde, anthrylaldehyde, phenanthrylaldehyde, salicylaldehyde, phenylacetaldehyde, 3-phenylpropionaldehyde, tolylaldehyde, ( N, N-dimethylamino) benzaldehyde, acetoxybenzaldehyde, 1-pyrenecarboxaldehyde, anisaldehyde. Moreover, the aromatic ketone used for the synthesis | combination of the said polymer is diaryl ketones, For example, diphenyl ketone, phenyl naphthyl ketone, dinaphthyl ketone, phenyl tolyl ketone, ditolyl ketone, 9-fluorenone is mentioned. The biphenol compound used for the synthesis of the polymer is not limited to one type of compound, and two or more types may be used, and aromatic compounds, heterocyclic compounds, aromatic aldehydes and aromatic ketones are also limited to one type of compound. Two or more of them may be used.

The resist underlayer film forming composition of the present invention can further contain a crosslinking agent. As the cross-linking agent, a cross-linkable compound having at least two cross-linking substituents is preferably used. Examples thereof include melamine compounds, substituted urea compounds and phenolic compounds having a crosslink forming substituent such as a methylol group or a methoxymethyl group. Specific examples include compounds such as methoxymethylated glycoluril and methoxymethylated melamine, and examples include tetramethoxymethylglycoluril, tetrabutoxymethylglycoluril, and hexamethoxymethylmelamine. Furthermore, examples of the substituted urea compound include tetramethoxymethylurea and tetrabutoxymethylurea. Examples of phenolic compounds include tetrahydroxymethyl biphenol, tetramethoxymethyl biphenol, and tetramethoxymethyl bisphenol.
As the cross-linking agent, a compound having at least two epoxy groups can also be used. Examples of such compounds include tris (2,3-epoxypropyl) isocyanurate, 1,4-butanediol diglycidyl ether, 1,2-epoxy-4- (epoxyethyl) cyclohexane, glycerol triglycidyl ether, and diethylene glycol. Diglycidyl ether, 2,6-diglycidylphenyl glycidyl ether, 1,1,3-tris [p- (2,3-epoxypropoxy) phenyl] propane, 1,2-cyclohexanedicarboxylic acid diglycidyl ester, 4,4 '-Methylenebis (N, N-diglycidylaniline), 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, trimethylolethane triglycidyl ether, bisphenol-A-diglycidyl ether, Daipel Co., Ltd. Epolide [registered trademark] GT-401, GT-403, GT-301, GT-302, Celoxide [registered trademark] 2021, 3000, Mitsubishi Chemical Corporation 1001, 1002 1003, 1004, 1007, 1009, 1010, 828, 807, 152, 154, 180S75, 871, 872, EPPN201, 202, EOCN-102, 103S, 104S, 1020 manufactured by Nippon Kayaku Co., Ltd. 1025, 1027, Denasel (registered trademark) EX-252, EX-611, EX-612, EX-614, EX-622, EX-622, EX-411, manufactured by Nagase ChemteX Corporation EX-512, EX-522, EX-421, EX-313, EX-314, EX-321, BAS Japan made of (stock) CY175, CY177, CY179, CY182, CY184, CY192, DIC (Ltd.) of Epichlone 200, the 400, the 7015, the 835LV, mention may be made of the same 850CRP. As the compound having at least two epoxy groups, an epoxy resin having an amino group can also be used. Examples of such epoxy resins include YH-434 and YH-434L (manufactured by Nippon Kayaku Epoxy Manufacturing Co., Ltd.).
As the crosslinking agent, a compound having at least two blocked isocyanate groups can also be used. Examples of such compounds include Takenate [registered trademark] B-830 and B-870N manufactured by Mitsui Chemicals, Inc., and VESTANAT [registered trademark] B1358 / 100 manufactured by Evonik Degussa.
As the cross-linking agent, a compound having at least two vinyl ether groups can also be used. Examples of such compounds include bis (4- (vinyloxymethyl) cyclohexylmethyl) glutarate, tri (ethylene glycol) divinyl ether, adipic acid divinyl ester, diethylene glycol divinyl ether, 1,2,4-tris (4-vinyl). Oxybutyl) trimellitate, 1,3,5-tris (4-vinyloxybutyl) trimellitate, bis (4- (vinyloxy) butyl) terephthalate, bis (4- (vinyloxy) butyl) isophthalate, ethylene glycol divinyl ether, 1 , 4-butanediol divinyl ether, tetramethylene glycol divinyl ether, tetraethylene glycol divinyl ether, neopentyl glycol divinyl ether, trimethylolpropane trivinyl ether Le, trimethylolethane trivinyl ether, hexanediol divinyl ether, 1,4-cyclohexanediol divinyl ether, tetraethylene glycol divinyl ether, pentaerythritol divinyl ether, and pentaerythritol trivinyl ether, and cyclohexanedimethanol divinyl ether.
One kind selected from these various crosslinking agents may be added, or two or more kinds may be added in combination. The content of the crosslinking agent is, for example, 2% by mass to 60% by mass with respect to the solid content excluding the solvent described later from the resist underlayer film forming composition of the present invention.

The resist underlayer film forming composition of the present invention can further contain an acidic compound. The acidic compound serves as a catalyst for promoting a crosslinking reaction, such as p-toluenesulfonic acid, trifluoromethanesulfonic acid, pyridinium-p-toluenesulfonate, salicylic acid, camphorsulfonic acid, 5-sulfosalicylic acid, 4-chlorobenzenesulfonic acid, Examples include 4-hydroxybenzenesulfonic acid, benzenedisulfonic acid, 1-naphthalenesulfonic acid, citric acid, benzoic acid, sulfonic acid compounds such as hydroxybenzoic acid, and carboxylic acid compounds, and inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid. be able to. Instead of the acidic compound or together with the acidic compound, a thermal acid generator can be contained. The thermal acid generator also serves as a catalyst for promoting the crosslinking reaction, and examples thereof include quaternary ammonium salts of trifluoromethanesulfonic acid. One kind selected from these acidic compounds and thermal acid generators may be added, or two or more kinds may be added in combination. The content ratio of the acidic compound or thermal acid generator is, for example, 0.1% by mass to 20% by mass with respect to the solid content excluding the solvent described later from the resist underlayer film forming composition of the present invention.

The resist underlayer film forming composition of the present invention can further contain a surfactant. Examples of the surfactant include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, polyoxyethylene alkyl ethers such as polyoxyethylene oleyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene Polyoxyethylene alkyl aryl ethers such as ethylene nonylphenyl ether, polyoxyethylene / polyoxypropylene block copolymers, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trioleate, sorbitan Sorbitan fatty acid esters such as tristearate, polyoxyethylene sorbitan monolaurate, polyoxyethylene Nonionic surfactants such as polyoxyethylene sorbitan fatty acid esters such as rubitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan tristearate, Ftop [registered trademark] ] EF301, EF303, EF352 (Mitsubishi Materials Electronics Chemical Co., Ltd.), MegaFuck [registered trademark] F171, F173, R-30, R-30-N, R-40, R- 40-LM (manufactured by DIC Corporation), Florard FC430, FC431 (manufactured by Sumitomo 3M Corporation), Asahi Guard [registered trademark] AG710, Surflon [registered trademark] S-382, SC101, SC102, SC103 SC104, SC105, SC10 (Asahi Glass Co., Ltd.) Fluorine-based surfactant and the like can be mentioned organosiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co.). One kind selected from these surfactants may be added, or two or more kinds may be added in combination. The content rate of the said surfactant is 0.01 mass% thru | or 5 mass% with respect to solid content except the solvent mentioned later from the resist underlayer film forming composition of this invention.

The resist underlayer film forming composition of the present invention can be prepared by dissolving each of the above components in an appropriate solvent, and is used in a uniform solution state. Examples of such solvents include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol, propylene glycol monomethyl ether, propylene glycol monopropyl ether, propylene glycol monomethyl ether acetate, propylene glycol. Propyl ether acetate, methyl cellosolve acetate, ethyl cellosolve acetate, toluene, xylene, methyl ethyl ketone, cyclopentanone, cyclohexanone, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, 2-hydroxy-3-methyl Methyl butanoate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethyl acetate, butyl acetate, ethyl lactate, lactic acid Examples include butyl, N, N-dimethylformamide, N, N-dimethylacetamide, and N-methylpyrrolidone. These organic solvents can be used alone or in combination of two or more. The ratio of the solid content excluding the organic solvent from the composition is, for example, 0.5% by mass to 30% by mass, preferably 0.8% by mass to 15% by mass.

The step of applying and baking the resist underlayer film forming composition of the present invention includes a base material (for example, a silicon wafer, which is a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a metal film such as aluminum or tungsten). The composition may be coated by a suitable coating method such as a spinner or a coater, and then baked using a heating means such as a hot plate. Baking conditions are appropriately selected from a baking temperature of 100 ° C. to 400 ° C. and a baking time of 0.3 minutes to 10 minutes.

An organopolysiloxane film is formed as a second resist underlayer film on the first resist underlayer film formed by the above process, and a resist pattern is formed thereon. The second resist underlayer film may be a SiON film or a SiN film formed by a vapor deposition method such as CVD or PVD. Further, an antireflection film (BARC) may be formed as a third resist underlayer film on the second resist underlayer film, and the third resist underlayer film is a resist shape correction film having no antireflection ability. May be. In the step of forming the resist pattern, exposure is performed through a mask (reticle) for forming a predetermined pattern or by direct drawing. As the exposure source, for example, g-line, i-line, KrF excimer laser, ArF excimer laser, EUV, or electron beam can be used. After the exposure, post-exposure heating (Post Exposure Bake) is performed as necessary. Thereafter, development is performed with a developer (for example, an aqueous 2.38 mass% tetramethylammonium hydroxide solution), and further rinsed with a rinse solution or pure water to remove the used developer. Thereafter, the resist pattern is dried and post-baked in order to improve adhesion to the base.

The etching process performed after forming the resist pattern is performed by dry etching. Examples of the etching gas used for dry etching include CHF ₃ , CF ₄ , and C ₂ F ₆ for the second resist underlayer film (organopolysiloxane film). From the resist underlayer film forming composition of the present invention, For the formed first resist underlayer film, for example, O ₂ , N ₂ O, NO ₂ can be mentioned, and for the surface having a step or a concave portion and / or a convex portion, for example, CHF ₃ , CF ₄ , C ₂ F ₆ is mentioned. Further, argon, nitrogen or carbon dioxide can be mixed with these gases.

EXAMPLES Hereinafter, although a synthesis example and an Example are given and demonstrated about this invention, this invention is not limited by the following description.

The weight average molecular weight and polydispersity shown in the following Synthesis Examples 1 to 3, Comparative Synthesis Example 1 and Comparative Synthesis Example 2 are measured by gel permeation chromatography (hereinafter abbreviated as GPC in this specification). based on. For the measurement, a GPC system manufactured by Tosoh Corporation is used, and the measurement conditions are as follows.
GPC column: TSKgel SuperMultipore [registered trademark] Hz-N (Tosoh Corporation)
Column temperature: 40 ° C
Solvent: tetrahydrofuran (THF)
Flow rate: 0.35 ml / min Standard sample: Polystyrene (Tosoh Corporation)

(Synthesis Example 1)
In a 200 mL four-necked flask, 3,3 ′, 5,5′-tetramethoxymethyl-4,4′-dihydroxybiphenyl (hereinafter abbreviated as TMOM-BP) (23.83 g, 0.066 mol, Honshu Chemical Industry Co., Ltd.), pyrene (27.00 g, 0.134 mol, manufactured by Tokyo Chemical Industry Co., Ltd.), p-toluenesulfonic acid monohydrate (0.53 g, 0.003 mol, Tokyo Chemical Industry Co., Ltd.) )) And 1,4-dioxane (119.84 g, manufactured by Kanto Chemical Co., Inc.) was added, stirred, and heated to dissolve until reflux was confirmed, and polymerization was started. Six hours later, the mixture was allowed to cool to 60 ° C. and then reprecipitated into methanol (1000 g, manufactured by Kanto Chemical Co., Inc.). The obtained precipitate was filtered, dried in a vacuum dryer at 60 ° C. for 12 hours, and a target polymer having a structural unit represented by the following formula (3) (hereinafter referred to as TMOM-Py and (Abbreviated) 28.6 g was obtained. The weight average molecular weight of the obtained TMOM-Py measured in terms of polystyrene by GPC was 2600.

(Synthesis Example 2)
In a 100 mL four-necked flask, TMOM-BP (2.21 g, 0.006 mol, manufactured by Honshu Chemical Industry Co., Ltd.), carbazole (5.00 g, 0.030 mol, manufactured by Tokyo Chemical Industry Co., Ltd.), 1-pyrenecarboxaldehyde (5.76 g, 0.025 mol, manufactured by Sigma-Aldrich), paratoluenesulfonic acid monohydrate (0.89 g, 0.006 mol, manufactured by Tokyo Chemical Industry Co., Ltd.) were added, and 1,4-dioxane ( 25.75 g (manufactured by Kanto Chemical Co., Inc.) was charged, stirred, and heated to dissolve until reflux was confirmed, and polymerization was started. After 7 hours, the mixture was allowed to cool to 60 ° C. and then reprecipitated into methanol (1000 g, manufactured by Kanto Chemical Co., Inc.). The obtained precipitate was filtered, dried in a vacuum dryer at 60 ° C. for 12 hours, and a target polymer having two structural units represented by the following formula (4) (hereinafter referred to as TMOM in the present specification). -Abbreviated as -Cz-PCA.) 6.3 g was obtained. The weight average molecular weight of the obtained TMOM-Cz-PCA measured by polystyrene conversion by GPC was 8,900.

(Synthesis Example 3)
In a 200 mL four-necked flask, TMOM-BP (13.93 g, 0.038 mol, manufactured by Honshu Chemical Industry Co., Ltd.), naphthalene (10.00 g, 0.078 mol, manufactured by Tokyo Chemical Industry Co., Ltd.), p-toluenesulfonic acid Hydrate (0.31 g, 0.002 mol, manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and 1,4-dioxane (56.56 g, manufactured by Kanto Chemical Co., Inc.) was further added and stirred. The temperature was raised until dissolution was confirmed, and polymerization was started. After 5 hours, the mixture was allowed to cool to 60 ° C. and then reprecipitated into methanol (1000 g, manufactured by Kanto Chemical Co., Inc.). The obtained precipitate was filtered, dried in a vacuum dryer at 60 ° C. for 12 hours, and a target polymer having a structural unit represented by the following formula (5) (hereinafter referred to as TMOM-Na in this specification). (Abbreviated) 5.9 g was obtained. The weight average molecular weight of the obtained TMOM-Na measured by polystyrene conversion by GPC was 5000.

(Comparative Synthesis Example 1)
Under nitrogen, carbazole (6.69 g, 0.040 mol, manufactured by Tokyo Chemical Industry Co., Ltd.), 9-fluorenone (7.28 g, 0.040 mol, manufactured by Tokyo Chemical Industry Co., Ltd.), paratoluene in a 100 mL four-necked flask. Sulfonic acid monohydrate (0.76 g, 0.0040 mol, manufactured by Tokyo Chemical Industry Co., Ltd.) was added, and 1,4-dioxane (6.69 g, manufactured by Kanto Chemical Co., Inc.) was further added and stirred. The temperature was raised to 100 ° C. to dissolve, and polymerization was started. After 24 hours, the mixture was allowed to cool to 60 ° C., diluted with chloroform (34 g, manufactured by Kanto Chemical Co., Inc.), and reprecipitated into methanol (168 g, manufactured by Kanto Chemical Co., Inc.). The obtained precipitate was filtered and dried in a vacuum dryer at 80 ° C. for 24 hours to obtain 9.37 g of a target polymer having a structural unit represented by the following formula (6). The weight average molecular weight of the obtained polymer measured by polystyrene conversion by GPC was 2,800.

Example 1
To 20 g of the polymer obtained in Synthesis Example 1, 0.06 g of Megafac R-30 (manufactured by DIC Corporation) as a surfactant was mixed and dissolved in 80 g of cyclohexanone to obtain a solution. Thereafter, the mixture is filtered using a polyethylene microfilter having a pore size of 0.10 μm, and further filtered using a polyethylene microfilter having a pore size of 0.05 μm to prepare a resist underlayer film forming composition used in a lithography process using a multilayer film. did.

(Example 2)
To 20 g of the polymer obtained in Synthesis Example 2, 0.06 g of Megafac R-30 (manufactured by DIC Corporation) was mixed as a surfactant and dissolved in 80 g of cyclohexanone to obtain a solution. Thereafter, the mixture is filtered using a polyethylene microfilter having a pore size of 0.10 μm, and further filtered using a polyethylene microfilter having a pore size of 0.05 μm to prepare a resist underlayer film forming composition used in a lithography process using a multilayer film. did.

(Example 3)
To 20 g of the polymer obtained in Synthesis Example 3, 0.06 g of Megafac R-30 (manufactured by DIC Corporation) was mixed as a surfactant and dissolved in 80 g of cyclohexanone to obtain a solution. Thereafter, the mixture is filtered using a polyethylene microfilter having a pore size of 0.10 μm, and further filtered using a polyethylene microfilter having a pore size of 0.05 μm to prepare a resist underlayer film forming composition used in a lithography process using a multilayer film. did.

(Comparative Example 1)
To 20 g of the polymer obtained in Comparative Synthesis Example 1, 0.06 g of Megafac R-30 (manufactured by DIC Corporation) was mixed as a surfactant and dissolved in 80 g of cyclohexanone to obtain a solution. Thereafter, the mixture is filtered using a polyethylene microfilter having a pore size of 0.10 μm, and further filtered using a polyethylene microfilter having a pore size of 0.05 μm to prepare a resist underlayer film forming composition used in a lithography process using a multilayer film. did.

(Comparative Example 2)
To 20 g of the polymer obtained in Comparative Synthesis Example 1, 3.0 g of TMOM-BP (produced by Honshu Chemical Industry Co., Ltd.) as a crosslinking agent, 0.6 g of pyridinium paratoluenesulfonate as a catalyst, and Megafac R-30 (as a surfactant) DIC Co., Ltd.) (0.06 g) was mixed and dissolved in 80 g of cyclohexanone to obtain a solution. Thereafter, the mixture is filtered using a polyethylene microfilter having a pore size of 0.10 μm, and further filtered using a polyethylene microfilter having a pore size of 0.05 μm to prepare a resist underlayer film forming composition used in a lithography process using a multilayer film. did.

(Measurement of film hardness)
The resist underlayer film forming compositions prepared in Examples 1 to 3, Comparative Example 1 and Comparative Example 2 were each applied onto a silicon wafer using a spin coater. The applied wafer was baked on a hot plate at 240 ° C. for 1 minute or at 400 ° C. for 2 minutes to form a resist underlayer film (film thickness: 0.25 μm). The hardness of the resist underlayer film was measured using a nanoindentation apparatus G200 (manufactured by Agilent Technologies). The results are shown in Table 1.

From the results of Table 1 above, the resist underlayer films formed by baking at 400 ° C. for 2 minutes using the resist underlayer film forming compositions of Examples 1 to 3 according to the present invention are those of Comparative Example 1 and Comparative Example 2. It was found that the resist underlayer film was harder than the resist underlayer film formed by baking under the same conditions using the resist underlayer film forming composition.

(Elution test for photoresist solvent)
The resist underlayer film forming compositions prepared in Examples 1 to 3 and Comparative Example 1 were each applied onto a silicon wafer using a spin coater. The applied wafer was baked on a hot plate at 400 ° C. for 2 minutes to form a resist underlayer film (film thickness: 0.25 μm). This resist underlayer film was immersed in a solvent (ethyl lactate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, cyclohexanone) used for the resist, and it was confirmed that the resist underlayer film was insoluble in these solvents.

(Measurement of optical parameters)
The resist underlayer film forming compositions prepared in Examples 1 to 3 were each applied on a silicon wafer using a spin coater. The applied wafer was baked on a hot plate at 240 ° C. for 1 minute or 400 ° C. for 2 minutes to form a resist underlayer film (film thickness 0.05 μm). These resist underlayer films were measured for refractive index (n value) and optical absorption coefficient (also referred to as k value or attenuation coefficient) at a wavelength of 193 nm using a spectroscopic ellipsometer. The results are shown in Table 2.

(Measurement of heat resistance)
The resist underlayer film forming compositions prepared in Examples 1 to 3 were each applied on a silicon wafer using a spin coater. The applied wafer was baked on a hot plate at 400 ° C. for 2 minutes to form a resist underlayer film (film thickness 0.2 μm). These resist underlayer films were scraped from the silicon wafer to obtain a powder. The thermogravimetric phenomenon at 400 ° C. of the obtained powder was measured with TG / DTA (TG-DTA2010SR manufactured by BRUKER). The results are shown in Table 3.

(Measurement of dry etching rate)
The etcher and etching gas used for the measurement of the dry etching rate are as follows.
Etcher: RIE-10NR (manufactured by Samco)
Etching gas: CF ₄
The resist underlayer film forming compositions prepared in Examples 1 to 3 were each applied on a silicon wafer using a spin coater. The applied wafer was baked on a hot plate at 240 ° C. for 1 minute or 400 ° C. for 2 minutes to form a resist underlayer film (film thickness 0.25 μm). Next, the dry etching rate of these resist underlayer films was measured using CF ₄ gas as an etching gas. In addition, a solution of phenol novolac resin (commercial product, weight average molecular weight Mw measured in terms of polystyrene by GPC is 2000, polydispersity Mw / Mn is 2.5) is applied onto a silicon wafer using a spin coater. The applied wafer was baked on a hot plate at 205 ° C. for 1 minute to form a phenol novolac resin film (film thickness: 0.25 μm). Next, CF ₄ gas was used as an etching gas, and the dry etching rate of the phenol novolac resin film was measured. When the dry etching rate of this phenol novolac resin film was set to 1.00, the dry etching rate of the resist underlayer film formed from the resist underlayer film forming composition prepared in Examples 1 to 3 was expressed as a dry etching rate ratio. The results calculated as are shown in Table 4. The smaller the dry etching rate, the higher the etching resistance against CF ₄ gas.
Dry etching rate ratio = (Dry etching rate of resist underlayer film) / (Dry etching rate of phenol novolac resin film)

(Check wiggling pattern width)
The resist underlayer film forming compositions prepared in Examples 1 to 3 and Comparative Example 2 were each applied onto a silicon wafer with a silicon oxide film using a spin coater. The applied wafer was baked on a hot plate at 400 ° C. for 2 minutes to form a resist underlayer film (film thickness 200 nm). A known silicon hard mask forming composition containing polysiloxane was applied onto the resist underlayer film and baked at 240 ° C. for 1 minute to form a silicon hard mask layer (film thickness: 45 nm). Further, a resist solution (PAR855 S90 (manufactured by Sumitomo Chemical Co., Ltd.)) was applied thereon and baked at 100 ° C. for 1 minute to form a resist layer (film thickness 120 nm). This resist layer was exposed using a mask at a wavelength of 193 nm, post-exposure heating (PEB, 105 ° C. for 1 minute), and then developed to obtain a resist pattern. Thereafter, dry etching was performed with a fluorine-based gas (component is CF ₄ ), and the resist pattern was transferred to the hard mask layer. Next, dry etching was performed with an oxygen-based gas (component is O ₂ ) to transfer the resist pattern to the resist underlayer film. Thereafter, dry etching was further performed with a fluorine-based gas (component is C ₄ F ₈ ) to remove the silicon oxide film on the silicon wafer. Each finally obtained pattern shape was observed with an electron microscope.

As the pattern width narrows, irregular pattern bending called wiggling is likely to occur. Therefore, the above-described pattern formation is performed using the resist underlayer film forming composition prepared in Examples 1 to 3. The process was performed, and the pattern width at which the resulting pattern began to wiggle was observed with an electron microscope. Since the processing of the substrate based on the faithful pattern becomes impossible due to the occurrence of pattern bending, it is necessary to process the substrate with the pattern width (limit pattern width) immediately before the occurrence of the pattern bending. The narrower the limit pattern width at which pattern bending starts to occur, the finer the substrate can be processed. A length measurement scanning electron microscope (manufactured by Hitachi High-Technologies Corporation) was used for resolution measurement. Table 5 shows the measurement results.

The resist underlayer film forming composition used in the lithography process using the multilayer film of the present invention can provide a resist underlayer film that can also have an effect as an antireflection film. Moreover, it turned out that the resist underlayer film forming composition of this invention has the heat resistance which can form a hard mask in the upper layer by CVD method. Further, even when the pattern width is narrowed, a good pattern is obtained in which pattern bending is difficult to occur, and a good pattern with no bend is obtained at a pattern width of at least about 50 nm.

Claims (6)

Following formula (1):

(Wherein X ¹ represents a divalent organic group having 6 to 20 carbon atoms having at least one aromatic ring optionally substituted with a halogeno group, a nitro group, an amino group or a hydroxy group, and X ² Represents an organic group having 6 to 20 carbon atoms having at least one aromatic ring optionally substituted with a halogeno group, a nitro group, an amino group or a hydroxy group, or a methoxy group.
A resist underlayer film forming composition comprising a polymer having a structural unit represented by formula (I) and a solvent. In the formula (1), the divalent organic group having 6 to 20 carbon atoms having at least one aromatic ring is a phenylene group, biphenylylene group, terphenylylene group, fluorenylene group, naphthylene group, anthrylene group, pyrenylene group, carbazolylene group. Or a group represented by the following formula (c) (wherein n represents 0 or 1), and the organic group having 6 to 20 carbon atoms having at least one aromatic ring is a phenyl group, a biphenylyl group, A terphenylyl group, a fluorenyl group, a naphthyl group, an anthryl group, a pyrenyl group, a carbazolyl group, or a group represented by the following formula (d-1) or the following formula (d-2) (wherein n represents 0 or 1) The composition for forming a resist underlayer film according to claim 1, wherein

The polymer is further represented by the following formula (2):

Wherein X ¹ is as defined in claim 1, R ³ represents a phenyl group, a naphthyl group, an anthryl group, a pyrenyl group, a thienyl group or a pyridyl group, and R ⁴ represents a hydrogen atom or a phenyl group. Alternatively, it represents a naphthyl group, and when R ³ and R ⁴ each represent a phenyl group, R ³ and R ⁴ together with the same carbon atom to which they are bonded may form a fluorene ring.
The resist underlayer film forming composition of Claim 1 or Claim 2 which has a structural unit represented by these. The resist underlayer film forming composition according to any one of claims 1 to 3, further comprising a surfactant. Furthermore, the resist underlayer film forming composition as described in any one of Claims 1 thru | or 4 containing a crosslinking agent. Furthermore, the resist underlayer film forming composition as described in any one of Claim 1 thru | or 5 containing an acidic compound and / or an acid generator.