WO2011125839A1

WO2011125839A1 - Composition for forming resist underlayer film and pattern forming method

Info

Publication number: WO2011125839A1
Application number: PCT/JP2011/058221
Authority: WO
Inventors: 慎也中藤; 信也峯岸; 和彦香村; 孝徳中野
Original assignee: Jsr株式会社
Priority date: 2010-03-31
Filing date: 2011-03-31
Publication date: 2011-10-13
Also published as: JPWO2011125839A1; TW201202856A; JP5794228B2

Abstract

A composition for forming a resist underlayer film, from which a resist underlayer film having excellent etching resistance and so on can be formed, comprising at least one member selected from the group consisting of photopolymerizable compounds represented by general formula (1) and general formula (2) together with a solvent. In general formulae (1) and (2), R¹¹, R¹² and R¹³ represent a hydrogen atom, etc.; R³ represents an n1-valent group derived from an aromatic compound; R⁴ represents a hydrogen atom, etc.; R⁵ represents a monovalent organic group derived from an aromatic compound; R⁶ represents an n2-valent organic group; X represents -COO-* [wherein * represents a bond binding to R⁶], etc.; n1 represents an integer of 2 to 4; and n2 represents an integer of 2 to 10.

Description

Resist underlayer film forming composition and pattern forming method

The present invention relates to a resist underlayer film forming composition and a pattern forming method. More specifically, the present invention relates to a resist underlayer film forming composition and a pattern forming method capable of forming a resist underlayer film having high elastic modulus and high etching resistance while maintaining a standing wave preventing effect.

In an integrated circuit element manufacturing method, in order to obtain a higher degree of integration, the processing size using a multi-layer resist process is miniaturized. In this process, a liquid resist underlayer film forming composition is first applied on a substrate to form a resist underlayer film (hereinafter sometimes simply referred to as “underlayer film”), and then a liquid is formed on the underlayer film. The photoresist composition (resist composition) is further applied to form a photoresist film (resist film). Next, the photoresist film is exposed using a reduction projection exposure apparatus (stepper) and then developed to obtain a photoresist pattern. Thereafter, the photoresist pattern is transferred to the resist underlayer film by dry etching. Next, by transferring the pattern of the resist underlayer film to which the photoresist pattern has been transferred to the substrate by dry etching, a substrate on which a desired pattern is formed can be obtained. The case where one kind of resist underlayer film is used is called a two-layer resist process, and the case where two kinds of resist underlayer films are used is sometimes called a three-layer resist process.

The resist underlayer film generally has a function as an antireflection film that absorbs radiation reflected from the substrate. In addition, the resist underlayer film formed immediately above the substrate is often formed of a material having a high carbon content (composition for forming a resist underlayer film). This is because if the carbon content is high, the etching resistance during substrate processing is improved, and more accurate pattern transfer is possible. As a composition for forming a resist underlayer film having a high carbon content, those containing a thermosetting phenol novolak and those containing a polymer having an acenaphthylene skeleton are known (see, for example, Patent Documents 1 and 2). ).

Further, as a composition for forming a resist underlayer film, a composition containing a photopolymerizable compound is known instead of a composition containing a resin such as thermosetting phenol novolak (see, for example, Patent Document 3).

JP 2000-143937 A JP 2001-40293 A International Publication No. 2006/115044 Pamphlet

However, the resist underlayer film forming compositions described in Patent Documents 1 and 2 have problems such as bending of the underlayer film pattern when the pattern is transferred from the resist underlayer film to the substrate by etching, and the pattern is satisfactorily applied to the substrate. There was a problem that it was impossible to transfer. Particularly, since the miniaturization of integrated circuit elements has recently been advanced, problems such as bending of a lower layer film pattern caused by heat have become a problem. Here, the cause of the bending of the lower layer film pattern is considered to be that the elastic modulus of the resist lower layer film is insufficient because the resins are not sufficiently crosslinked.

The resist underlayer film forming composition described in Patent Document 3 contains a photopolymerizable compound, but is intended to obtain a material having low etching resistance. What is the resist underlayer film of the present invention? Disclose materials for different applications.

The present invention has been made to solve the above-described problems of the prior art, and is capable of forming a resist underlayer film having a high elastic modulus and high etching resistance while maintaining a standing wave prevention effect. It aims at providing the composition for lower layer film formation, and the pattern formation method.

As a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that the above-mentioned problems can be achieved by photopolymerizing a compound having a specific structure to form a crosslinked structure. The invention has been completed.

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

[1] (A) At least one photopolymerizable compound selected from the group consisting of a photopolymerizable compound represented by the following general formula (1) and a photopolymerizable compound represented by the following general formula (2) And (B) a resist underlayer film forming composition containing a solvent.

(In the general formula (1), R ¹¹ to R ¹³ are each independently a monovalent group derived from an aromatic compound, a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an alkyl group having 3 to 20 carbon atoms. cycloalkyl group, a nitro group, a cyano ^group, -COR 2, shows a -COOR ² or -CON ^(R ₂₎ 2 ^{^(where,} -COR 2, -COOR ^2, and -CON ^(R ₂₎ in _2, ^{R 2} Each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or a monovalent organic group derived from an aromatic compound, and having a substituent. Provided that any one of R ¹¹ to R ¹³ is a monovalent group derived from an aromatic compound, a nitro group, a cyano group, —COR ² , —COOR ² or —CON (R ² ) is a ₂ .R ³ may have a substituent, .n1 showing the n1 valent organic radical derived from aromatic compounds is an integer of 2-4.)

(In the general formula (2), R ⁴ is independently of each other a monovalent organic group derived from an aromatic compound, a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a cycloalkyl having 3 to 20 carbon atoms. group, a nitro group, a cyano ^group, -COR 7, showing a -COOR ⁷ or -CON ^(R _{7) 2} ^{^(where,} -COR 7, in -COOR ⁷ or ^{_{^{-CON (R 7) 2, R}}} 7 are mutually And independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or a monovalent organic group derived from an aromatic compound, and may have a substituent. R ⁵ represents a monovalent organic group derived from an aromatic compound which may have a substituent, R ⁶ represents an n2-valent organic group, and X represents —COO—. * or -CONH- * the show ( "*" represents a bond that binds to ^{R 6).} 2 is an integer of 2-10.)

[2] The photopolymerizable compound represented by the general formula (1) is a compound represented by the following general formula (1-1), and the photopolymerizable compound represented by the general formula (2) is The composition for forming a resist underlayer film according to the above [1], which is a compound represented by the following general formula (2-1).

(In general formula (1-1), R ¹ independently represents a hydrogen atom or a cyano group. R ² independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, 3 to 20 cycloalkyl groups, or monovalent organic groups derived from aromatic compounds, which may have a substituent, R ³ may have a substituent, an aromatic group An n1-valent organic group derived from a compound, where n1 is an integer of 2 to 4.)

(In the general formula (2-1), R ⁴¹ independently represents a hydrogen atom or a cyano group, R ⁶ represents an n2 valent hydrocarbon group, and n2 represents an integer of 2 to 10. R ^P is .n _p indicating a substituent is an integer of 0-5.)

[3] For forming a resist underlayer film according to [1] or [2], wherein the photopolymerizable compound represented by the general formula (1) is a compound represented by the following general formula (1-11): Composition.

(In General Formula (1-11), R ¹ independently represents a hydrogen atom or a cyano group. R ² independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, 3 to 20 cycloalkyl groups or monovalent organic groups derived from aromatic compounds, which may have a substituent, n1 represents an integer of 2 to 4.

[4] The resist underlayer according to any one of [1] to [3], wherein the photopolymerizable compound represented by the general formula (1) is a compound represented by the following general formula (1-111): Film forming composition.

(In General Formula (1-111), R ¹ independently represents a hydrogen atom or a cyano group. R ² independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, 3 to 20 cycloalkyl groups or a monovalent organic group derived from an aromatic compound, which may have a substituent)

[5] A coating film forming step of coating the composition for forming a resist underlayer film according to any one of [1] to [4] on a substrate to be processed to form a coating film, and the formed coating film An underlayer film forming step of forming a resist underlayer film on the substrate to be processed by irradiating the film with radiation and curing the coating film; and applying a resist composition on the resist underlayer film and drying the resist composition A resist film forming process for forming a film; an exposure process for selectively irradiating the resist film with radiation to expose the resist film; and a resist pattern having a predetermined pattern by developing the exposed resist film Forming a predetermined pattern on the substrate to be processed by etching the resist underlayer film and the substrate to be processed using the resist pattern as a mask. Pattern forming method and a etching process for forming the same pattern as.

The resist underlayer film forming composition of the present invention is at least one selected from the group consisting of a photopolymerizable compound represented by the general formula (1) and a photopolymerizable compound represented by the general formula (2). Since it contains a photopolymerizable compound, when irradiated with light, the cross-linking structure formed by the polymerization reaction of these compounds becomes strong, and the elastic modulus is maintained while maintaining the standing wave prevention effect. In addition, a resist underlayer film having high etching resistance can be formed.

According to the pattern forming method of the present invention, a resist underlayer film forming composition is applied on a substrate to be processed to form a coating film, and the formed coating film is irradiated with radiation to be applied. And a lower layer film forming step of forming a resist lower layer film on a substrate to be processed by curing the film, so that the resist lower layer film to be formed has a high elastic modulus and effectively prevents defects such as pattern bending. . Therefore, a good pattern can be formed on the substrate to be processed.

Hereinafter, although the form for implementing this invention is demonstrated, this invention is not limited to the following embodiment. That is, it is understood that modifications and improvements as appropriate to the following embodiments are also within the scope of the present invention based on ordinary knowledge of those skilled in the art without departing from the spirit of the present invention. Should be.

In the present specification, the “substituent” is not particularly limited. For example, —R ^S1 , —R ^S2 —O—R ^S1 , —R ^S2 —CO—R ^S1 , —R ^S2 —CO— OR ^S1 , —R ^S2 —O—CO—R ^S1 , —R ^S2 —OH, —R ^S2 —COOH, —R ^S2 —CN, —R ^S2 —NH ₂ , —R ^S2 —NR ^S1 ₂ etc. Can do. R ^S1 independently represents an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or an aryl group having 6 to 30 carbon atoms, and one of hydrogen atoms contained in these groups. Part or all may be substituted with a fluorine atom. R ^S2 is independently of each other a single bond, an alkanediyl group having 1 to 10 carbon atoms, a cycloalkanediyl group having 3 to 20 carbon atoms, an arylene group having 6 to 30 carbon atoms, or hydrogen contained in these groups A group in which some or all of the atoms are substituted with fluorine atoms. Further, “having a substituent” means having one or more of the above substituents alone, or having one or more of each of the above substituents.

[1] Composition for forming a resist underlayer film:
The resist underlayer film forming composition of the present invention is selected from the group consisting of (A) a photopolymerizable compound represented by the general formula (1) and a photopolymerizable compound represented by the general formula (2). Containing at least one photopolymerizable compound and (B) a solvent. Since this resist underlayer film forming composition contains the photopolymerizable compound (A), when the compound is irradiated with light, the cross-linked structure formed by the polymerization reaction of these compounds is strong. Thus, the elastic modulus and etching resistance are high while maintaining the standing wave preventing effect. Therefore, according to such a composition for forming a resist underlayer film, it is possible to form a resist underlayer film that hardly causes pattern bending.

[1-1] (A) Photopolymerizable compound:
In the photopolymerizable compound represented by the general formula (1) and the photopolymerizable compound represented by the general formula (2), the carbon-carbon double bond is converted to another carbon- by irradiation with light. It is a compound that undergoes recombination of carbon double bond and bond to form a cyclobutane ring. That is, by containing the (A) photopolymerizable compound, in the resist underlayer film (in the coating film formed by the resist underlayer film forming composition of the present invention), (A) two photopolymerizable compounds are contained. It is strongly cross-linked by a carbon-carbon bond to form a cross-linked structure. Therefore, a hard resist underlayer film can be formed by using such a compound ((A) photopolymerizable compound). Here, the conventional resist underlayer forming composition forms a crosslinked structure in the resist underlayer film by using a crosslinking agent or the like, but since this crosslinked structure is due to a single bond, the strength of the bond is low. Not enough (bonding strength was not enough). Therefore, the pattern may be bent during etching (so-called pattern bending may occur). On the other hand, since the cross-linked structure formed by the photopolymerizable compound (A) has a stronger bonding force than that of a single bond, it is considered that a hard resist underlayer film is obtained and the pattern does not bend during etching.

In the general formula (1), the monovalent group derived from an aromatic compound represented by R ¹¹ to R ¹³ is a group obtained by removing one hydrogen atom from an aromatic hydrocarbon having 6 to 10 carbon atoms. Can be mentioned. Examples of the aromatic hydrocarbon include aromatic hydrocarbons such as benzene and naphthalene; nitrogen-containing aromatic hydrocarbons such as pyrrole, pyridine, pyrazine, pyrimidine, pyridazine, triazine and indole; and oxygen-containing aromatic carbons such as furan. Hydrogen: Sulfur-containing aromatic hydrocarbons such as thiophene. Among these, a group derived from benzene, naphthalene, and pyridine is preferable because of high etching resistance. The monovalent group derived from the aromatic compound may have a substituent.

In the general formula (1), the alkyl group having 1 to 10 carbon atoms represented by R ¹¹ to R ¹³ is methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n- Linear alkyl groups such as hexyl group, n-octyl group, n-dodecyl group, n-tetradecyl group and n-octadecyl group, branching such as isopropyl group, isobutyl group, t-butyl group, neopentyl group and 2-ethylhexyl group An alkyl group can be mentioned. Among these, a methyl group, an ethyl group, an i-propyl group, and an i-butyl group are preferable. The alkyl group may have a substituent.

In the general formula (1), the cycloalkyl group having 3 to 20 carbon atoms represented by R ¹¹ to R ¹³ is a monocyclic cycloalkyl group such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, or a cyclooctyl group. An alkyl group; and a polycyclic cycloalkyl group such as a tricyclodecanyl group, a tetracyclododecyl group, a norbornyl group, and an adamantyl group. The cycloalkyl group may have a substituent.

-COR ^2, ^{R 2} is preferably in the ^{^{_{-COOR 2, -CON (R 2)}}} 2, as described above, independently of one another, a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, cycloalkyl of 3 to 20 carbon atoms An alkyl group or a monovalent organic group derived from an aromatic compound. Among these, a hydrogen atom, a methyl group, an ethyl group, an i-propyl group, an i-butyl group, a phenyl group, and a pyridyl group are preferable.

In the general formula (1), examples of the group represented by “—CR ¹¹ ═CR ¹² R ¹³ ” include groups represented by the following general formulas (a) to (n). In the following general formulas (a) to (n), R ²¹ independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a cycloalkyl group having 3 to 20 carbon atoms. R ¹⁴ represents a monovalent group derived from an aromatic compound which may have a substituent. R ² is each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or a monovalent organic group derived from an aromatic compound. A wavy line indicates that the direction of coupling is unspecified.

In the general formulas (a) to (n), R ¹⁴ is a monovalent group derived from an aromatic compound similar to the monovalent group represented by R ¹¹ to R ¹³ derived from an aromatic compound. The monovalent group derived from this aromatic compound may have a substituent. Among monovalent groups derived from these aromatic compounds, groups derived from benzene, naphthalene, and pyridine are preferable because a resist underlayer film having high etching resistance can be formed.

In the general formula (a) ~ ^(n), the cycloalkyl group of the alkyl group or 3 to 20 carbon atoms having 1 to 10 carbon atoms represented as ^{R 21,} 1 carbon atoms represented as the ^{R 2} ~ Examples thereof are the same as 10 alkyl groups or cycloalkyl groups having 3 to 20 carbon atoms. Among these, a group represented by the following general formula (a-1) is preferable from the viewpoint of easy availability of raw materials.

(In the general formula (a-1), R ¹ represents a hydrogen atom or a cyano group. R ² independently of each other represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a cyclohexane having 3 to 20 carbon atoms. (It is a monovalent organic group derived from an alkyl group or an aromatic compound.)

In the general formula (1), the n1-valent organic group derived from the aromatic compound represented by R ³ includes a group obtained by removing (n1) hydrogen atoms from an aromatic hydrocarbon having 6 to 10 carbon atoms. Can be mentioned. Examples of the aromatic hydrocarbon include aromatic hydrocarbons such as benzene and naphthalene; nitrogen-containing aromatic hydrocarbons such as pyrrole, pyridine, pyrazine, pyrimidine, pyridazine, triazine and indole; and oxygen-containing aromatic carbons such as furan. Hydrogen: Sulfur-containing aromatic hydrocarbons such as thiophene. Among these, since a resist underlayer film having high etching resistance can be formed, a group derived from benzene, naphthalene, and pyridine is preferable. R ³ may have a substituent.

In the general formula (1), n1 is preferably 2 or 3, and more preferably 2.

In the compound represented by the general formula (1-1), the group represented by “—CR ¹¹ = CR ¹² R ¹³ ” in the general formula (1) is represented by the general formula (a-1). It is a group. Further, the compound represented by the general formula (1-11) is a compound in the case where R ³ is a benzene-derived divalent group in the general formula (1-1). Further, the compound represented by the general formula (1-111) is a compound in the case where n1 is 2 in the general formula (1-11).

Specific examples of the photopolymerizable compound represented by the general formula (1) include the following compounds.

Specific examples of the photopolymerizable compound represented by the general formula (1-111) include the following compounds.

Among the above compounds, the following compounds are preferred because crosslinking proceeds easily (a crosslinked structure is formed) and the crosslinking density is increased by light irradiation.

The photopolymerizable compound represented by the general formula (1) can be obtained, for example, by condensing an aromatic ring having a plurality of formyl groups and cyanoacetic acid esters in the presence of a base.

In the general formula (2), the monovalent organic group derived from the aromatic compound represented by R ⁵ includes a monovalent group represented by R ¹¹ to R ¹³ and derived from the aromatic compound. A monovalent group derived from the same aromatic compound can be exemplified, and the monovalent group derived from this aromatic compound may have a substituent. Among these, a group derived from benzene and pyridine is preferable because of high etching resistance.

In the general formula (2), a monovalent organic group derived from an aromatic compound represented by R ⁴ , an alkyl group having 1 to 10 carbon atoms, and a cycloalkyl group having 3 to 20 carbon atoms are A monovalent group derived from an aromatic compound represented by R ¹¹ to R ¹³ in the general formula (1), an alkyl group having 1 to 10 carbon atoms, and a cycloalkyl group having 3 to 20 carbon atoms; The same thing can be illustrated.

In the general formula (2), examples of the group represented by “—X—CR ⁴ ═CR ⁴ R ⁵ ” include groups represented by the following general formulas (o) to (z). . In the following general formulas (o) to (z), R ²¹ independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a cycloalkyl group having 3 to 20 carbon atoms. R ⁵ represents a monovalent organic group derived from an aromatic compound which may have a substituent. R ⁸ independently of one another represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or a monovalent organic group derived from an aromatic compound, You may have. A wavy line indicates that the direction of coupling is unspecified.

Among the above compounds, a group represented by the following general formula (o-1) is preferable from the viewpoint of easy availability of raw materials.

(In the general formula (o-1), R ⁴¹ represents a hydrogen atom or a cyano group. R ^p represents a substituent. N _p represents an integer of 0 to 5.)

In the general formula (2), examples of the n2-valent organic group represented by R ⁶ include n2-valent hydrocarbon groups. Examples of such hydrocarbon groups include methane, ethane, n-propyl group, n-butane, n-pentane, n-hexane, n-octane, n-dodecane, n-tetradecane, and n-octadecane. Chain alkanes: Chain hydrocarbons such as branched alkanes such as isopropane, isobutane, t-butane, neopentane, 2-ethylhexane, etc., monocyclic cyclohexane such as cyclopropane, cyclobutane, cyclopentane, cyclohexyl group, cyclooctane, etc. An alkane; a group in which n2 hydrogen atoms are removed from a cyclic hydrocarbon such as polycyclocycloalkane such as tricyclodecane, tetracyclododecane, norbornene, adamantane and the like.

N2 in the general formula (2) is preferably 2 to 8, and particularly preferably 2 to 6.

In the compound represented by the general formula (2-1), the group represented by “—X—CR ⁴ ═CR ⁴ R ⁵ ” in the general formula (2) is represented by the general formula (o-1). This is the case when the group is represented.

Specific examples of the photopolymerizable compound represented by the general formula (2) include compounds represented by the following formulas (B-1) to (B-5). Among these, a compound represented by the formula (B-5) is preferable because a resist underlayer film having high etching resistance can be formed.

The photopolymerizable compound represented by the general formula (2) can be obtained, for example, by reacting cinnamic acid with a carbon source (for example, dimethylformamide or alkyl bromide) in the presence of a base.

In addition, the composition for resist underlayer film formation of this invention is the photopolymerizable compound represented by the said General formula (1), and the photopolymerizable compound represented by the said General formula (2), respectively. It may contain, may contain both the photopolymerizable compound represented by the general formula (1) and the photopolymerizable compound represented by the general formula (2), It is preferable that the photopolymerizable compound represented by the general formula (1) is contained alone. This is because the photopolymerizable compound represented by the general formula (1) can form a resist underlayer film having high etching resistance because the photocrosslinkable sites are connected by an aromatic ring.

[1-2] (B) Solvent:
(B) A solvent will not be specifically limited if it can dissolve the (A) photopolymerizable compound contained. Specific examples of the solvent (B) include propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, n-butyl acetate, ethyl 3-ethoxypropionate, methyl 3-methoxypropionate having high coatability, -Heptanone, γ-butyrolactone, cyclohexanone and the like.

(B) The content of the solvent is 5 to 80 parts by mass with respect to 100 parts by mass of the total amount of the photopolymerizable compound represented by the general formula (1) and the photopolymerizable compound represented by the general formula (2). Preferably, the amount is 5 to 40 parts by weight, more preferably 8 to 30 parts by weight. When the content is within the above range, (A) the photopolymerizable compound can be dissolved satisfactorily, and striation occurs due to the film thickness of the resist underlayer film formed being too thin. It is preferable in that there is little fear.

[1-3] Additive:
The composition for forming a resist underlayer film of the present invention may further contain an additive in addition to (A) the photopolymerizable compound and (B) the solvent. Examples of the additive include a binder resin, a radiation absorber, a surfactant, a storage stabilizer, an antifoaming agent, and an adhesion assistant.

Examples of the binder resin include various thermoplastic resins and thermosetting resins. A thermoplastic resin is a component which has the effect | action which provides the fluidity | liquidity, mechanical characteristic, etc. of the added thermoplastic resin to a lower layer film | membrane. The thermosetting resin is a component that is cured by heating and becomes insoluble in a solvent, and has a function of preventing intermixing between the resulting resist underlayer film and the resist film formed thereon. It can be preferably used as a resin. Among these, thermosetting resins such as urea resins, melamine resins, and aromatic hydrocarbon resins are preferable. In addition, these binder resin may be used individually by 1 type, and may be used in combination of 2 or more type.

The blending amount of the binder resin is (A) 100 parts by mass of the photopolymerizable compound (the total amount of the photopolymerizable compound represented by the general formula (1) and the photopolymerizable compound represented by the general formula (2) is 100 parts by mass. ) Is preferably 20 parts by mass or less, and more preferably 10 parts by mass or less. When the blending amount is more than 20 parts by mass, the binder resin may inhibit the polymerization of the (A) photopolymerizable compound. Therefore, a resist underlayer film having a high elastic modulus may not be obtained.

Specific examples of the radiation absorber include oil-soluble dyes, disperse dyes, basic dyes, methine dyes, pyrazole dyes, imidazole dyes, hydroxyazo dyes, and the like; bixin derivatives, norbixine, stilbene, Fluorescent brighteners such as 4,4′-diaminostilbene derivatives, coumarin derivatives, pyrazoline derivatives; hydroxyazo dyes, tinuvin 234 (trade name, manufactured by Ciba Geigy), tinuvin 1130 (trade name, manufactured by Ciba Geigy), etc. Ultraviolet absorbers; aromatic compounds such as anthracene derivatives and anthraquinone derivatives. These radiation absorbers can be used alone or in admixture of two or more.

The compounding amount of the radiation absorber is preferably 100 parts by mass or less, and more preferably 50 parts by mass or less, with respect to 100 parts by mass of the (A) photopolymerizable compound. When the amount is more than 100 parts by mass, the radiation absorber may inhibit the photoreaction of the (A) photopolymerizable compound.

Surfactant is a component having an effect of improving coatability, striation, wettability, developability and the like. Specifically, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene-n-octylphenyl ether, polyoxyethylene-n-nonylphenyl ether, polyethylene glycol dilaurate, polyethylene glycol diester Nonionic surfactants such as stearate, and 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), MegaFuck F171, F172, F173 (above, Dainippon Ink and Chemicals, Inc.) (Manufactured by Kogyo Co., Ltd.), FLORARD FC430, FC431, FC135, FC135, FC93 (above, manufactured by Sumitomo 3M), Asahi Guard AG710, Surflon S382, SC101, SC102, SC103, SC104, SC105, SC106 ( As mentioned above, Asahi Glass Co., Ltd.) can be mentioned. These surfactants can be used alone or in admixture of two or more. These surfactants may be used individually by 1 type, and may be used in combination of 2 or more type.

The compounding amount of the surfactant is preferably 15 parts by mass or less, and more preferably 10 parts by mass or less with respect to 100 parts by mass of the (A) photopolymerizable compound. If the amount is more than 15 parts by mass, the surfactant may affect the performance of the resist underlayer film (decrease the performance of the resist underlayer film).

[2] Pattern formation method:
The pattern forming method of the present invention is a coating film forming step (hereinafter referred to as “step (1)”) in which the resist underlayer film forming composition of the present invention described above is applied onto a substrate to be processed to form a coating film. And a lower layer film forming step (hereinafter referred to as “step (2)”) that forms a resist lower layer film on the substrate to be processed by irradiating the formed coating film with radiation and curing the coating film. And a resist film forming step in which a resist composition is applied on the formed resist underlayer film and dried to form a resist film (hereinafter sometimes referred to as “step (3)”) , An exposure step of exposing the resist coating by selectively irradiating the formed resist coating with radiation (hereinafter sometimes referred to as “step (4)”), and developing the exposed resist coating A resist pattern with A pattern forming step to be formed (hereinafter may be referred to as “step (5)”), and etching the resist underlayer film and the substrate to be processed by using the resist pattern as a mask, thereby forming the same pattern as the predetermined pattern on the substrate to be processed And an etching step (hereinafter, may be referred to as “step (6)”).

According to such a pattern forming method, since the step (1) and the step (2) are provided, the elastic modulus of the resist underlayer film to be formed is high, and defects such as pattern bending are effectively prevented. Therefore, a good pattern can be formed on the substrate to be processed.

Step (1) is a step of coating the resist underlayer film forming composition of the present invention on a substrate to be processed to form a coating film.

As the substrate to be processed, for example, a silicon wafer, a wafer coated with aluminum, or the like can be used.

Further, the method for applying the resist underlayer film forming composition to the substrate to be processed is not particularly limited, and for example, it can be carried out by an appropriate method such as spin coating, cast coating, roll coating or the like.

Next, step (2) is a step of forming a resist underlayer film on the substrate to be processed by irradiating the formed coating film with radiation and curing the coating film.

The radiation to be irradiated can be appropriately selected from, for example, visible light, ultraviolet light, far ultraviolet light, X-ray, electron beam, γ-ray, molecular beam, ion beam and the like.

The film thickness of the resist underlayer film is usually 0.1 to 5 μm.

In addition, before performing step (2) (that is, after step (1)), a step (1a) for forming an intermediate layer (intermediate coating) on the resist underlayer film may be further provided as necessary. Good. 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 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. Materials commercially available under trade names such as “AR-3” and “AR-19” manufactured by the company can be used. Further, as the inorganic oxide, for example, a coating type spin-on glass material manufactured by JSR, polysiloxane formed by a CVD method, titanium oxide, alumina oxide, tungsten oxide, 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, a 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.

Next, step (3) is a step of forming a resist film by coating a resist composition on the formed resist underlayer film and drying it. Specifically, after a resist composition is applied so that the resulting resist film has a predetermined thickness, the solvent in the film is volatilized by pre-baking to form a resist film.

Examples of the resist composition include a positive or negative chemically amplified resist composition containing a photoacid generator, a positive resist composition comprising an alkali-soluble resin and a quinonediazide-based photosensitizer, and an alkali-soluble resin and a crosslink And negative resist compositions composed of an agent. The resist composition used when forming the resist film on the resist underlayer film has a solid content concentration of usually about 5 to 50% by mass, and is generally filtered through, for example, a filter having a pore diameter of about 0.2 μm. Then, it is used for formation of a resist film. In this step (step (3)), a commercially available resist composition can be used as it is.

The coating method of the resist composition 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 to be used, but is usually about 30 to 200 ° C., preferably 50 to 150 ° C.

Next, step (4) is a step of exposing the resist film by selectively irradiating the formed resist film with radiation.

The radiation used for the exposure is appropriate from visible light, ultraviolet light, far ultraviolet light, X-rays, electron beams, γ rays, molecular beams, ion beams, etc., depending on the type of photoacid generator used in the resist composition. In particular, far ultraviolet rays are preferable, and in particular, KrF excimer laser (248 nm), ArF excimer laser (193 nm), F ₂ excimer laser (wavelength 157 nm), Kr ₂ excimer laser (wavelength 147 nm), ArKr excimer laser (Wavelength 134 nm), extreme ultraviolet light (wavelength 13 nm, etc.) and the like are preferable.

Next, step (5) is a step of developing the exposed resist film to form a resist pattern having a predetermined pattern.

The developer used in this step is appropriately selected depending on the type of resist composition used. Specifically, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, dimethylethanol Amine, triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, pyrrole, piperidine, choline, 1,8-diazabicyclo [5.4.0] -7-undecene, 1,5-diazabicyclo [4.3. 0] -5-nonene and the like.

In addition, water-soluble organic solvents, for example, alcohols such as methanol and ethanol, and surfactants can be added to these alkaline aqueous solutions in appropriate amounts.

Further, after development with the developer, the resist pattern is formed by washing and drying.

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 70 to 150 ° C.

Next, step (6) is a step of forming the same pattern as the predetermined pattern on the substrate to be processed by etching the resist underlayer film and the substrate to be processed using the resist pattern as a mask. Examples of dry etching include gas plasma such as oxygen plasma.

Hereinafter, the present invention will be specifically described based on Examples and Comparative Examples, but the present invention is not limited to these Examples and Comparative Examples. In addition, when only described as “parts” and “%”, it is based on mass unless otherwise specified.

[Weight average molecular weight (Mw)]:
The weight average molecular weight (Mw) was determined by using Tosoh's GPC columns (G2000HXL: 2, G3000HXL: 1), flow rate: 1.0 ml / min, elution solvent: tetrahydrofuran, column temperature: 40 ° C. , And measured by a gel permeation chromatograph (detector: differential refractometer) using monodisperse polystyrene as a standard.

Example 1
A separable flask equipped with a thermometer was charged with 100 parts of isophthalaldehyde, 200 parts of isobutyl cyanoacetate, 1 part of piperidine, and 4000 parts of 4-methyl-2-pentanol under a nitrogen atmosphere and stirred at 60 ° C. And reacted for 1 hour to obtain a reaction solution. Thereafter, the reaction solution was allowed to stand for 1 day, and the precipitated solid was filtered and then washed with 4-methyl-2-pentanol to obtain a white solid. This white solid was a compound represented by the following formula (3).

10 parts of the compound represented by the formula (3) were dissolved in 100 parts of propylene glycol monomethyl ether to obtain a mixed solution. Thereafter, this mixed solution was filtered through a membrane filter having a pore size of 0.1 μm to obtain a resist underlayer film forming composition (1). And the following various evaluation was performed about this resist underlayer film forming composition (1).

(1) Formation of ArF positive resist pattern:
First, a resist underlayer film forming composition (1) was applied on a silicon wafer having a diameter of 8 inches by spin coating to form a coating film. Next, the coating film on the wafer is cured by irradiating the coating film on the wafer with 300 mJ of light having an intensity of 20 mW / cm ² by a small high-precision exposure apparatus for R & D manufactured by TOPCON, and an underlayer film having a film thickness of 0.3 μm is formed. Obtained. Next, an intermediate layer composition solution (trade name “NFC SOG080”, manufactured by JSR Corporation) for a three-layer resist process was spin-coated on this lower layer film. Then, it heated at 200 degreeC for 60 second on the hotplate. Thereafter, the film was further heated at 300 ° C. for 60 seconds to form an intermediate layer film having a thickness of 0.05 μm on the lower layer film. Next, a resist composition was spin-coated on this intermediate layer coating, and pre-baked at 130 ° C. for 90 seconds on a hot plate to form a resist coating having a thickness of 0.2 μm.

In addition, as the resist composition, one prepared as follows was used.

First, in a separable flask equipped with a reflux tube, 8-methyl-8-t-butoxycarbonylmethoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene (referred to as “monomer (a)”) 29 parts, 8-methyl-8-hydroxytetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] dodec-3-ene (referred to as “monomer (b)”) 10 parts, maleic anhydride (referred to as “monomer (c)”) 18 parts, 2,5-dimethyl-2,5 4 parts of hexanediol diacrylate, 1 part of t-dodecyl mercaptan, 4 parts of azobisisobutyronitrile and 60 parts of 1,2-diethoxyethane were charged and polymerized at 70 ° C. for 6 hours with stirring. Thereafter, the reaction solution was poured into a large amount of a mixed solvent of n-hexane / i-propyl alcohol (mass ratio = 1/1) to obtain a coagulated product. The obtained solidified body was washed several times with the above mixed solvent and then vacuum-dried to obtain a resin for a resist composition (yield 60%). Thereafter, the obtained resist composition resin and the resist composition solvent were mixed to prepare a resist composition.

The obtained resin for a resist composition has each repeating unit derived from each of the monomers (a), (b) and (c), and the molar ratio of each of these repeating units is 64: 18:18. Moreover, the weight average molecular weight (Mw) was 27,000. In addition, as a solvent for resist compositions, a mixed solvent (mass ratio 7: 3) of propylene glycol monomethyl ether acetate and cyclohexanone was used.

Next, using a ArF excimer laser exposure apparatus (lens numerical aperture of 0.78, exposure wavelength of 193 nm) manufactured by NIKON, the resist film was exposed through the mask pattern only for the optimal exposure time. Next, after post-baking at 130 ° C. for 90 seconds on a hot plate, the exposed resist film was developed at 25 ° C. for 1 minute using a 2.38 mass% aqueous tetramethylammonium hydroxide solution. . Thereafter, it was washed with water and dried to obtain a resist film (resist film (resist pattern) on which a positive resist pattern was formed) formed to form a line-and-space pattern (1L / 1S) having a line width of 70 nm. .

(2) Standing wave prevention effect:
(1) The following criteria are obtained by observing with a scanning electron microscope whether a standing wave has an influence on the resist film on which the positive resist pattern formed by the evaluation of the ArF positive resist pattern is formed. It was evaluated with. The case where the influence of the standing wave due to the reflection from the lower layer film was not observed on the side surface of the resist pattern was good (denoted as “A” in Table 1), and the case where the influence of the standing wave was observed was poor ( In Table 1, “C” is indicated), and the case where the influence of the standing wave is slightly observed is indicated (indicated by “B” in Table 1).

(3) Elastic modulus:
A resist underlayer film forming composition (1) was spin-coated on a silicon wafer having a diameter of 8 inches to form a coating film. Next, the coating film on the wafer is cured by irradiating the coating film on the wafer at 300 mJ with light having an intensity of 20 mW / cm ² using a small high-precision exposure apparatus for R & D manufactured by TOPCON, and a resist having a film thickness of 0.3 μm. A lower layer film was obtained. Thereafter, the elastic modulus (GPa) of the lower layer film was measured by a nanoindenter method and evaluated. Evaluation criteria set the thing whose elasticity modulus was 10 GPa or more as the pass "G", and made the thing less than 10 GPa the rejection "N".

(4) Etching resistance:
A resist underlayer film forming composition (1) was spin-coated on a silicon wafer having a diameter of 8 inches to form a coating film. Next, the coating film on the wafer is cured by irradiating the coating film on the wafer at 300 mJ with light having an intensity of 20 mW / cm ² using a small high-precision exposure apparatus for R & D manufactured by TOPCON, and a resist having a film thickness of 0.3 μm. A lower layer film was obtained. Thereafter, this lower layer film is subjected to etching treatment (etching conditions are pressure: 0.03 Torr, high frequency power: 3000 W, Ar / CF4 = 40/100 sccm, substrate temperature: 20 ° C.), and the lower layer film after the etching treatment The film thickness was measured. Then, the etching rate (nm / min) was calculated from the relationship between the reduction amount of the film thickness and the processing time. The smaller the calculated value, the higher the etching resistance of the resist underlayer film, which is preferable. The calculated value was evaluated according to the following evaluation criteria. A case of less than 0.9 nm / min was designated as “A”, a case of 0.9 nm / min to 1.2 nm / min was designated as “B”, and a case of exceeding 1.2 nm / min was designated as “C”. In Table 1, this evaluation result is shown in the column of “Etching rate”.

In the resist underlayer film forming composition (1) of this example, the evaluation of the standing wave prevention effect is “A”, the evaluation result of the elastic modulus is “G”, and the evaluation result of the etching resistance is “A”. "Met.

(Example 2)
A separable flask equipped with a thermometer was charged with 100 parts of cinnamic acid, 200 parts of sodium bicarbonate, 1 part of tetra-n-butylammonium chloride, and 4000 parts of N, N-dimethylformaldehyde under a nitrogen atmosphere and stirred. The reaction solution was obtained by reacting at 110 ° C. for 40 hours. Thereafter, methanol was added to the obtained reaction solution to obtain a precipitate. The resulting precipitate was filtered to obtain a white solid. This white solid was a compound represented by the following formula (4).

The composition for forming a resist underlayer film of Example 2 was the same as Example 1 except that the compound represented by Formula (4) was used instead of the compound represented by Formula (3). 2) was obtained. About the obtained resist underlayer film forming composition (2), each said evaluation was performed like Example 1. FIG. The evaluation results are shown in Table 1.

(Example 3)
A composition for forming a resist underlayer film of Example 3 in the same manner as in Example 1 except that the compound represented by the following formula (5) was used instead of the compound represented by the above formula (3). (3) was obtained. Each evaluation was performed like Example 1 about the obtained composition for resist underlayer film formation (3). The evaluation results are shown in Table 1.

Example 4
The composition for forming a resist underlayer film of Example 4 is the same as Example 1 except that the compound represented by the following formula (6) is used instead of the compound represented by the above formula (3). (4) was obtained. Each evaluation was performed like Example 1 about the obtained composition for resist underlayer film formation (4). The evaluation results are shown in Table 1.

(Example 5)
The composition for forming a resist underlayer film of Example 5 is the same as Example 1 except that the compound represented by the following formula (7) is used instead of the compound represented by the above formula (3). (5) was obtained. Each evaluation was performed like Example 1 about the obtained composition for resist underlayer film formation (5). The evaluation results are shown in Table 1.

(Comparative Example 1)
A separable flask equipped with a thermometer was charged with 100 parts of 2,7-dihydroxynaphthalene, 30 parts of formalin, 1 part of p-toluenesulfonic acid and 150 parts of propylene glycol monomethyl ether in a nitrogen atmosphere while stirring. Polymerization was performed at 80 ° C. for 6 hours to obtain a reaction solution. Thereafter, the reaction solution was diluted with 100 parts of n-butyl acetate, and the organic layer was washed with a large amount of water / methanol (mass ratio: 1/2) mixed solvent. Thereafter, the mixed solvent was distilled off to obtain a polymer. The weight average molecular weight (Mw) of the obtained polymer was 1800.

A resist underlayer film forming composition (6) of Comparative Example 1 was obtained in the same manner as in Example 1 except that 10 parts of the polymer was used instead of the compound represented by the formula (3). It was. Each evaluation was performed in the same manner as in Example 1 using the obtained resist underlayer film forming composition (6). The evaluation results are shown in Table 1. In this comparative example, the resist underlayer film (thickness: 0.3 μm) is formed by forming a coating film on the substrate (silicon wafer having a diameter of 8 inches) with the resist underlayer film forming composition (6), and then applying this coating. The substrate on which the film was formed was placed on a hot plate and heated at 300 ° C. for 120 seconds to form the substrate.

(Comparative Example 2)
Instead of the compound represented by the formula (3), 10 parts of bis (4-glycidyloxyphenyl) methane (a compound represented by the following formula (8)) and 1 part of triphenylsulfonium trifluoromethanesulfonate were used. Except for this, a composition for forming a resist underlayer film (7) of Comparative Example 2 was obtained in the same manner as Example 1. Each evaluation was performed like Example 1 about the obtained composition for resist underlayer film formation (7). The evaluation results are shown in Table 1.

As is apparent from Table 1, the resist underlayer film forming compositions of Examples 1 to 5 had the same standing wave prevention effect as the resist underlayer film forming compositions of Comparative Examples 1 and 2, It was confirmed that a resist underlayer film having a high elastic modulus and etching resistance can be formed.

The composition for forming a resist underlayer film of the present invention can be suitably used as a material for a resist underlayer film formed by a multilayer resist process in an integrated circuit element manufacturing method.

Claims

(A) at least one photopolymerizable compound selected from the group consisting of a photopolymerizable compound represented by the following general formula (1) and a photopolymerizable compound represented by the following general formula (2);
(B) A resist underlayer film forming composition containing a solvent.

(In the general formula (1), R 11 to R 13 are each independently a monovalent group derived from an aromatic compound, a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an alkyl group having 3 to 20 carbon atoms. cycloalkyl group, a nitro group, a cyano group, -COR 2, shows a -COOR 2 or -CON (R 2) 2 (where, -COR 2, -COOR 2, and -CON (R 2) in 2, R 2 Each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or a monovalent organic group derived from an aromatic compound, and having a substituent. Provided that any one of R 11 to R 13 is a monovalent group derived from an aromatic compound, a nitro group, a cyano group, —COR 2 , —COOR 2 or —CON (R 2 ) is a 2 .R 3 may have a substituent, .n1 showing the n1 valent organic radical derived from aromatic compounds is an integer of 2-4.)

(In the general formula (2), R 4 is independently of each other a monovalent organic group derived from an aromatic compound, a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a cycloalkyl having 3 to 20 carbon atoms. group, a nitro group, a cyano group, -COR 7, showing a -COOR 7 or -CON (R 7) 2 (where, -COR 7, in -COOR 7 or -CON (R 7) 2, R 7 are mutually And independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or a monovalent organic group derived from an aromatic compound, and may have a substituent. R 5 represents a monovalent organic group derived from an aromatic compound which may have a substituent, R 6 represents an n2-valent organic group, and X represents —COO—. * or -CONH- * the show ( "*" represents a bond that binds to R 6). 2 is an integer of 2-10.)
The photopolymerizable compound represented by the general formula (1) is a compound represented by the following general formula (1-1), and the photopolymerizable compound represented by the general formula (2) is 2. The resist underlayer film forming composition according to claim 1, which is a compound represented by the formula (2-1).

(In general formula (1-1), R 1 independently represents a hydrogen atom or a cyano group. R 2 independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, 3 to 20 cycloalkyl groups, or monovalent organic groups derived from aromatic compounds, which may have a substituent, R 3 may have a substituent, an aromatic group An n1-valent organic group derived from a compound, where n1 is an integer of 2 to 4.)

(In the general formula (2-1), R 41 independently represents a hydrogen atom or a cyano group, R 6 represents an n2 valent hydrocarbon group, and n2 represents an integer of 2 to 10. R P is .n p indicating a substituent is an integer of 0-5.)
3. The resist underlayer film forming composition according to claim 1, wherein the photopolymerizable compound represented by the general formula (1) is a compound represented by the following general formula (1-11).

(In General Formula (1-11), R 1 independently represents a hydrogen atom or a cyano group. R 2 independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, 3 to 20 cycloalkyl groups or monovalent organic groups derived from aromatic compounds, which may have a substituent, n1 represents an integer of 2 to 4.
The composition for forming a resist underlayer film according to any one of claims 1 to 3, wherein the photopolymerizable compound represented by the general formula (1) is a compound represented by the following general formula (1-111): object.

(In General Formula (1-111), R 1 independently represents a hydrogen atom or a cyano group. R 2 independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, 3 to 20 cycloalkyl groups or a monovalent organic group derived from an aromatic compound, which may have a substituent)
A coating film forming step of coating the resist underlayer film forming composition according to any one of claims 1 to 4 on a substrate to be processed to form a coating film;
An underlayer film forming step of forming a resist underlayer film on the substrate to be processed by irradiating the formed coating film with radiation and curing the coating film;
A resist film forming step of applying a resist composition on the resist underlayer film and drying to form a resist film; and
An exposure step of selectively irradiating the resist film with radiation to expose the resist film;
A pattern forming step of developing the exposed resist film to form a resist pattern having a predetermined pattern;
An etching process for forming the same pattern as the predetermined pattern on the substrate to be processed by etching the resist underlayer film and the substrate to be processed using the resist pattern as a mask.