Composition for forming resist underlayer film, resist underlayer film, method for manufacturing resist underlayer film, patterning process, and method for manufacturing semiconductor device

Abstract

To provide a composition for forming a resist underlayer film with which it is possible to form a resist underlayer film that exhibits excellent processing resistance and excellent gas permeability.SOLUTION: The present invention provides a composition for forming a resist underlayer film, containing: (A) a novolak resin having a repeating unit structure represented by the following general formula (I) and / or (II); and (B) an organic solvent, where R1 is a combination of at least two kinds in a single resin.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a composition for forming a resist underlayer film, a resist underlayer film, a method for producing a resist underlayer film, a pattern forming method, and a method for producing a semiconductor device. In particular, the present invention relates to a composition for forming a resist underlayer film for nanoimprinting that can be used for fine patterning by a photo-nanoimprinting method in the process of producing a semiconductor device. [Background technology]

[0002] In the manufacture of semiconductor devices and MEMS, which require miniaturization, photo-nanoimprinting technology, which can form fine structures on the order of several nanometers on a substrate, has been attracting attention. In a typical photo-nanoimprinting technology, a liquid resist composition is first dropped onto a pattern formation area on a substrate using an inkjet method or the like, and the droplets of the resist composition are spread on the substrate (press-spreading). Next, this resist composition is molded using a mold that is transparent to the irradiated light and on which a pattern has been formed. At this time, the droplets of the resist composition spread over the entire gap between the substrate and the mold by capillary action (spreading). The resist composition also fills the inside of the recess on the mold by capillary action (filling). The time until the spreading and filling are completed is the filling time. After the filling of the resist composition is completed, the resist composition is hardened by irradiating light, and then the two are separated. By carrying out these steps, a resist pattern having a predetermined shape is formed on the substrate.

[0003] In the demolding process of the photo-nanoimprint technique, the adhesion between the resist composition and the substrate is important. If the adhesion between the resist composition and the substrate is low, when the mold is detached in the demolding process, a part of the photocured product obtained by curing the resist composition may peel off while still adhering to the mold, resulting in a pattern peeling defect. In this context, a technique for forming an adhesion layer between the resist composition and the substrate, which is a layer for adhering the resist composition to the substrate, has been proposed as a technique for improving the adhesion between the resist composition and the substrate (Patent Document 1).

[0004] Patent Document 2 discloses a reversal process in nanoimprinting, and since Spin On Carbon (SOC) is used as the processed layer, properties such as processing resistance, embeddability, and flatness are required. In addition, the nanoimprinting process on SOC generally involves applying an adhesive layer material for nanoimprinting onto the SOC and then performing imprinting on the SOC. In addition, bubbles generated when a mold is pressed against a curable composition (resist) can cause molding defects, so it is necessary to eliminate the bubbles. Patent Document 3 improves the oxygen permeability of the mold side, but further improvement in defoaming is expected with miniaturization. In light of this background, it has been proposed to eliminate gas from the underlayer film side, and there is a demand for the development of an underlayer film with high gas permeability (Non-Patent Document 1).

[0005] Gas permeability tends to increase with a hydrophobic film for hydrophobic gases and with a hydrophilic film for highly hydrophilic gases. Since relatively hydrophobic gases such as He, H2, N2, and air are selected as the atmosphere for the process of pressing the mold, Patent Document 4 and Patent Document 5 propose a highly hydrophobic film with a high water contact angle as the underlayer film material. However, these documents do not discuss the actual gas permeability. Furthermore, in reality, a relatively hydrophilic gas such as CO2 may be selected. On the other hand, it is known that gas permeability is greatly affected not only by hydrophilicity but also by film density and compounding agents. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2013-202982 [Patent Document 2] Special Publication No. 2006-524919 [Patent Document 3] Patent No. 6703253 specification [Patent Document 4] International Publication No. 2021-125036 [Patent Document 5] International Publication No. 2023-145923 [Non-patent literature]

[0007] [Non-Patent Document 1] Proc. SPIE 10958, Novel Patterning Technologies for Semiconductors, MEMS / NEMS, and MOEMS 2019, 109580H Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a composition for forming a resist underlayer film capable of forming a resist underlayer film exhibiting excellent processing resistance and excellent gas permeability, a resist underlayer film which is a cured product of a coating film comprising the composition, a method for producing a resist underlayer film using the composition, a pattern formation method, and a method for producing a semiconductor device. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention provides a polymerizable composition comprising: (A) a novolak resin having a repeating unit structure represented by the following general formula (I) and / or (II); (B) an organic solvent; The present invention provides a composition for forming a resist underlayer film, comprising: [ka] (In the above general formulas (I) and (II), Ar1 and Ar2 are each independently a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted heteroaryl group having 6 to 30 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms condensed or connected to an aliphatic ring or an ether ring, or a plurality of substituted or unsubstituted aryl groups having 6 to 30 carbon atoms connected to each other via a linear, branched or cyclic hydrocarbon group, an ether group or a carbonyl group; Ar1 ​​may be one type or a combination of multiple types in the same resin, and Ar2 may be one type or a combination of multiple types in the same resin. R1 is and a combination of at least two or more of them, which are a hydrogen atom, a substituted or unsubstituted linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted linear, branched or cyclic alkenyl group having 2 to 20 carbon atoms, or a substituted or unsubstituted linear, branched or cyclic alkynyl group having 2 to 20 carbon atoms. R2 is any one of a substituted or unsubstituted linear, branched or cyclic saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms, an amino group, a thiol group, and a halogen atom. n1 is an integer of 1 or more. 、 n2, n3, and n4 are integers equal to or greater than 0.

[0010] The component (A) is a novolac resin, and therefore the main skeleton contains an aromatic ring, and the mechanical strength (also called processing resistance) required to withstand processing is excellent. Furthermore, by combining at least two or more types of R1, at least two types of repeating units with different OR1 groups are present in the same resin, and / or repeating units containing two or more types of OR1 groups are present. In this way, the steric hindrance of the substituent introduced via the ether structure can suppress dense packing between aromatic rings and dense crosslinking reactions, and can suppress densification of the film obtained by curing the composition. By suppressing densification, the film obtained by curing the composition can exhibit excellent gas permeability. In this way, by appropriately selecting the main skeleton structure and the substituent structure, it is possible to achieve both the contradictory performances of processing resistance and gas permeability. In addition, by combining at least two or more types of R1, it is possible to suppress the crystallinity of the resin, suppress densification of the film, and also impart thermal fluidity. Therefore, the composition for forming a resist underlayer film of the present invention can provide a resist underlayer film that is expected to have excellent embedding ability and flatness after baking, good film hardness, and mechanical strength capable of withstanding processing (good processing resistance), as well as low film density and good gas permeability.

[0011] In the above formulas (I) and (II), at least one of R1 is a structure R selected from the group consisting of groups represented by the following formula (III-1): 1-1 It is preferable that: [ka] (In formula (III-1), * represents a bond to an oxygen atom.)

[0012] In the above general formulas (I) and (II), at least one of R1 is a structure R selected from the group consisting of groups represented by the above general formula (III-1). 1-1If the composition has a cyclic structure, the processing resistance is not easily impaired, while the cyclic structure itself has a low density, and furthermore, the steric hindrance is large, so that the effect of preventing the aromatic rings from being closely adjacent to each other is large, and a film with a low film density can be provided. That is, according to the composition for forming a resist underlayer film of this preferred embodiment, a resist underlayer film that is excellent in processing resistance and can exhibit better gas permeability can be provided.

[0013] Furthermore, in the above formulas (I) and (II), R1 is a structure R selected from the group consisting of groups shown in the following (III-1): 1-1 and a structure R selected from the group consisting of groups represented by the following formula (III-2): 1-2 It is a combination of structure R 1-1 The ratio of a to R 1-2 When the ratio of a to b is taken as the ratio, it is preferable that the ratios a and b satisfy the relationships 1≦a≦99, 1≦b≦99, and a+b=100. [ka] (In formulas (III-1) and (III-2), * represents a bond to an oxygen atom.)

[0014] In the above formulas (I) and (II), R1 is a structure R selected from the group consisting of groups shown in the following (III-1): 1-1 and a structure R selected from the group consisting of groups represented by the following formula (III-2): 1-2 If combined with, structure R 1-1 Many of the structures have a cyclic structure and are less likely to impair processing resistance, while the cyclic structure itself has a low density and, because of its large steric hindrance, is highly effective in preventing aromatic rings from being closely adjacent to each other, making it possible to realize a film with low film density. 1-2Since it acts as a thermosetting group, it can increase the curing property of the resin when the curing property of the resin alone is insufficient. In addition, by sealing the hydroxyl group, it is possible to increase the hydrophobicity, and it is possible to increase the affinity with hydrophobic gases such as He and N2, thereby improving the gas permeability. Furthermore, by containing two or more different kinds of substituents, it is expected that it will have excellent solubility and excellent thermal fluidity. Therefore, it is possible to provide a resist underlayer film that is expected to have good processing resistance, excellent embedding property and flatness, and further to have low film density and good gas permeability when baked.

[0015] In addition, in the above general formula (II), Ar2 is preferably a benzene ring.

[0016] In the above formula (II), if Ar2 is a benzene ring, various raw materials with different substituents are available, so that the physical properties can be tuned to meet the required performance.

[0017] Furthermore, in the above general formulas (I) and (II), it is preferable that Ar1 is selected from the group consisting of structures represented by the following formula (Ar-1). [ka]

[0018] In the above general formulas (I) and (II), if Ar1 is a benzene ring or a naphthalene ring, there are many types of monomers, and various physical properties can be tuned by selecting a substituent according to the required performance. In addition, all of the other structures shown in the above formula (Ar-1) have two benzene rings in one molecule, which are further bonded or condensed with a linear or cyclic alkyl group or ether group, so that the structure can suppress packing between aromatic rings, and the film after baking can be suppressed from becoming dense. Therefore, a resist underlayer film that exhibits good gas permeability and further has good flatness can be provided.

[0019] In addition, in the above general formula (II), n3+n4 is preferably an integer of 2 or more.

[0020] In the above general formula (II), if the composition is one in which n3+n4 is an integer of 2 or more, the number of substituents increases, and therefore the effects of suppressing packing and suppressing crystallinity can be improved.

[0021] The (A) novolak resin preferably has a weight average molecular weight Mw of 2,000 to 8,000 in terms of polystyrene as determined by gel permeation chromatography.

[0022] When the weight average molecular weight Mw of the (A) novolak resin is 2000 to 8000, the amount of low molecular weight components that cause sublimation during baking is reduced, making it difficult for film formation defects to occur, and it is possible to prevent poor filling properties due to a decrease in thermal fluidity caused by an excessively large molecular weight from being induced, thereby providing a composition for forming an underlayer film.

[0023] The composition for forming a resist underlayer film is applied to a substrate to obtain a coating film, the coating film is baked at 180° C. for 60 seconds, and then additionally baked at 350° C. for 60 seconds. The thickness of the coating film after the baking is designated as FT-1; After the additional baking, OK73 thinner obtained by mixing propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate in a ratio of 7:3 was dispensed onto the coating film, and then the coating film was left for 30 seconds, and then the coating film was spin-dried, and then the coating film was baked at 100°C for 60 seconds to evaporate the OK73 thinner. When the thickness of the coating film is FT-2, 100.5<{(FT-2) / (FT-1)}×100 It is preferable that the above formula is satisfied.

[0024] If the ratio is 100.5<{(FT-2) / (FT-1)}×100, it indicates that the film after rework has swelled compared to the film immediately after firing, and it is considered that a porous film with many fine pores that allow the OK73 thinner to penetrate is formed immediately after firing, suggesting that a film with low film density is formed rather than a dense film. Therefore, the film obtained from the composition of this embodiment is expected to have excellent gas permeability.

[0025] It is preferable that the composition further contains a surfactant (C).

[0026] (C) The surfactant can suppress film formation defects such as striations on the film surface and disturbances in the in-plane uniformity.

[0027] (D) a crosslinking agent, The composition for forming a resist underlayer film is applied to a substrate to obtain a coating film, the coating film is baked at 180° C. for 60 seconds, and then additionally baked at 350° C. for 60 seconds. The thickness of the coating film after the baking is designated as FT-1; After the additional baking, OK73 thinner obtained by mixing propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate in a ratio of 7:3 was dispensed onto the coating film, and then the coating film was left for 30 seconds, and then the coating film was spin-dried, and then the coating film was baked at 100°C for 60 seconds to evaporate the OK73 thinner. When the thickness of the coating film is FT-2, 100<{(FT-2) / (FT-1)}×100<101 It is also preferable that the above formula is satisfied.

[0028] (D) The crosslinking agent can accelerate curing when the resin alone does not cure sufficiently, and can increase the hardness of the film and strengthen its processing resistance. It can also suppress swelling of the film after rework, making it possible to adjust the degree of porosity of the film.

[0029] (E) further comprising a thermally decomposable resin; The composition for forming a resist underlayer film is applied to a substrate to obtain a coating film, the coating film is baked at 180° C. for 60 seconds, and then additionally baked at 350° C. for 60 seconds. The thickness of the coating film after the baking is designated as FT-1; After the additional baking, OK73 thinner obtained by mixing propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate in a ratio of 7:3 was dispensed onto the coating film, and then the coating film was left for 30 seconds, and then the coating film was spin-dried, and then the coating film was baked at 100°C for 60 seconds to evaporate the OK73 thinner. When the thickness of the coating film is FT-2, 101<{(FT-2) / (FT-1)}×100 It is also preferable that the above formula is satisfied.

[0030] (E) By including a thermally decomposable resin, the thermally decomposable resin decomposes during baking and sublimes from within the film, which can form additional pores within the film. This increases the swelling of the film after reworking, making it possible to adjust the degree of porosity of the film.

[0031] (D) a crosslinking agent and (E) a thermally decomposable resin; The composition for forming a resist underlayer film is applied to a substrate to obtain a coating film, the coating film is baked at 180° C. for 60 seconds, and then additionally baked at 350° C. for 60 seconds. The thickness of the coating film after the baking is designated as FT-1; After the additional baking, OK73 thinner obtained by mixing propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate in a ratio of 7:3 was dispensed onto the coating film, and then the coating film was left for 30 seconds, and then the coating film was spin-dried, and then the coating film was baked at 100°C for 60 seconds to evaporate the OK73 thinner. When the thickness of the coating film is FT-2, 100<{(FT-2) / (FT-1)}×100 It is also preferable that the above formula is satisfied.

[0032] (D) Crosslinking agent and (E) thermally decomposable resin have opposing effects as film density adjusters. Therefore, when using both at the same time, it is sufficient to confirm only the hardening of the film. When comparing the difference in film thickness before and after rework, it is sufficient if (FT-2)>(FT-1).

[0033] Furthermore, (F) an acid generator may be further contained.

[0034] (F) By including an acid generator, it may be possible to enhance the curability of a resin or the decomposition property of a thermally decomposable resin.

[0035] The composition for forming a resist underlayer film of the present invention may be for use in nanoimprinting.

[0036] The use of the resist underlayer film formed by the composition according to the present invention is not particularly limited. For example, the composition for forming a resist underlayer film of the present invention may be for nanoimprinting. The resist underlayer film formed by the composition for forming a resist underlayer film of the present invention has good processing resistance, excellent embedding property and flatness, and further has low film density and good gas permeability. Therefore, the composition of the present invention can realize a resist underlayer film that is very useful for nanoimprinting.

[0037] The present invention also provides a resist underlayer film which is a cured product of a coating film made of the composition for forming a resist underlayer film of the present invention.

[0038] The resist underlayer film formed from the composition for forming a resist underlayer film of the present invention has good processing resistance, excellent embedding property and flatness, and further has low film density and can exhibit good gas permeability.

[0039] In addition, the present invention provides a method for producing a coating film by applying the composition for forming a resist underlayer film of the present invention onto a semiconductor substrate; baking the coating film to obtain a resist underlayer film. The present invention provides a method for producing a resist underlayer film, comprising the steps of:

[0040] Such a method for producing a resist underlayer film of the present invention uses the composition for forming a resist underlayer film of the present invention, and therefore it is possible to realize a resist underlayer film that has good processing resistance, excellent embedding ability and flatness, and further has low film density and good gas permeability.

[0041] The present invention also provides a pattern forming method, comprising the steps of: forming a resist underlayer film on a semiconductor substrate from the composition for forming a resist underlayer film of the present invention; forming a curable composition film on the resist underlayer film; contacting the curable composition film with a mold; a step of irradiating the curable composition film with light or an electron beam to form a cured film; separating the cured film from the mold; The present invention provides a pattern forming method comprising the steps of:

[0042] According to the pattern formation method by the imprint method of the present invention, a resist underlayer film having good processing resistance, excellent embedding property and flatness, and further having low film density and good gas permeability can be used. Therefore, according to the pattern formation method by the imprint method of the present invention, air bubbles generated when a mold is pressed against a curable composition film can be quickly removed, and a fine pattern can be formed.

[0043] The step of forming a curable composition film on the resist underlayer film may also include forming an adhesion layer and / or a silicone layer containing 99% by mass or less of Si on the resist underlayer film by coating or vapor deposition, and forming a curable composition film thereon.

[0044] By forming an adhesion layer, it is possible to sufficiently suppress pattern peeling during the process of removing the mold. In addition, by forming a silicone layer containing 99 mass % or less of Si, it is possible to adjust the optical properties of the film, enabling reflection control, etc.

[0045] The present invention also provides a method for manufacturing a semiconductor device, comprising the steps of: forming a resist underlayer film on a semiconductor substrate from the composition for forming a resist underlayer film of the present invention; forming a resist film on the resist underlayer film; a step of irradiating the resist film with light or an electron beam, and then developing the resist film to form a resist pattern; a step of etching the resist underlayer film using the formed resist pattern as a mask to obtain a patterned underlayer film; processing the semiconductor substrate using the patterned underlayer film as a mask; The present invention provides a method for manufacturing a semiconductor device, comprising the steps of:

[0046] The present invention also provides a method for manufacturing a semiconductor device, comprising the steps of: forming a resist underlayer film on a semiconductor substrate from the composition for forming a resist underlayer film of the present invention; forming a hard mask on the resist underlayer film; further forming a resist film on the hard mask; a step of irradiating the resist film with light or an electron beam, and then developing the resist film to form a resist pattern; Etching the hard mask using the formed resist pattern as a mask to obtain a patterned hard mask; Etching the underlayer film using the patterned hard mask as a mask to obtain a patterned resist underlayer film; processing the semiconductor substrate using the patterned resist underlayer film as a mask; The present invention provides a method for manufacturing a semiconductor device, comprising the steps of:

[0047] The composition for forming a resist underlayer film of the present invention can provide a resist underlayer film that has good processing resistance, excellent embedding property and flatness, and further has low film density and good gas permeability, and is therefore useful in a method for manufacturing a semiconductor device using a pattern formation method other than the nanoimprint method, for example, a multilayer resist method, as described above. That is, according to the method for manufacturing a semiconductor device of the present invention, a fine pattern can be formed on a semiconductor substrate. Effect of the Invention

[0048] As described above, the resist film-forming composition of the present invention is a composition containing (A) a novolac resin having a repeating unit structure represented by the above general formula (I) and / or (II) and (B) an organic solvent, and since the novolac resin (A) contains an aromatic ring, it has sufficient mechanical strength to withstand processing, and furthermore, since dense packing between aromatic rings and dense crosslinking reaction are inhibited, it is possible to suppress the film from becoming dense. Therefore, according to the resist underlayer film-forming composition of the present invention, it is possible to provide a resist underlayer film that has good processing resistance, excellent embedding property and flatness, and further has low film density and good gas permeability.

[0049] Furthermore, the resist underlayer film of the present invention exhibits good processing resistance, excellent embedding properties and flatness, and further has a low film density and good gas permeability.

[0050] Furthermore, according to the method for forming a resist underlayer film of the present invention, it is possible to produce a resist underlayer film that exhibits good processing resistance, excellent embedding ability and flatness, as well as low film density and good gas permeability.

[0051] Furthermore, according to the pattern forming method of the present invention, air bubbles generated when the mold is pressed against the curable composition film can be quickly removed, and a fine pattern can be formed.

[0052] Furthermore, according to the method for manufacturing a semiconductor device of the present invention, a semiconductor device having a fine pattern formed on a semiconductor substrate can be manufactured. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0053] As described above, in the fine patterning process, there has been a demand for the development of an underlayer film that has excellent embedding ability, processing resistance, and also high gas permeability in order to form a resist underlayer film that can transfer a resist pattern to a substrate to be processed with higher accuracy.

[0054] As a result of intensive research into the above-mentioned problems, the present inventors have focused on the characteristics of aromatic ring-containing polymers that have sufficient mechanical strength but form dense films due to packing, and have considered the introduction of a structure that inhibits packing and have conducted intensive research. As described above, photo-nanoimprint technology that can form fine structures on the order of several nanometers on a substrate has attracted attention, but there is a problem that defects occur due to bubbles that are generated when the mold is pressed, and so far, improvements have been made to the gas permeability of the mold side. On the other hand, currently, improvements only on the mold side are insufficient, and it is thought that bubbles can be eliminated from the underlayer film (resist underlayer film) side as well, but material development has not progressed and there are still few options. In addition, when used as an underlayer film, it is preferable for the material to have processing resistance and flattening properties. The present inventors have focused on novolac resins, which have excellent processing resistance, and thought that by etherifying at least one hydroxyl group in the novolac resin, it is possible to suppress the packing between aromatic rings, form a film with low film density, and become a film with high gas permeability. Furthermore, the inventors believed that by introducing multiple ether substituents, it would be possible to enhance the packing suppression effect and impart fluidity, resulting in a composition for forming a resist underlayer film with excellent filling properties and planarization characteristics.

[0055] As a result of further intensive research, the present inventors have found that a composition containing (A) a novolak resin having a repeating unit structure represented by the above general formula (I) and / or (II) and (B) an organic solvent can serve as a composition for forming a resist underlayer film that has mechanical strength sufficient to withstand processing, excellent embedding ability and flatness, and further has a low film density and is therefore expected to have excellent gas permeability, thereby completing the present invention.

[0056] That is, the present invention relates to a polymerizable composition comprising: (A) a novolak resin having a repeating unit structure represented by the following general formula (I) and / or (II); (B) an organic solvent; The composition for forming a resist underlayer film is characterized by comprising: [ka] (In the above general formulas (I) and (II), Ar1 and Ar2 are each independently a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted heteroaryl group having 6 to 30 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms condensed or connected to an aliphatic ring or an ether ring, or a plurality of substituted or unsubstituted aryl groups having 6 to 30 carbon atoms connected to each other via a linear, branched or cyclic hydrocarbon group, an ether group or a carbonyl group; Ar1 ​​may be one type or a combination of multiple types in the same resin, and Ar2 may be one type or a combination of multiple types in the same resin. R1 is and a combination of at least two or more of them, which are a hydrogen atom, a substituted or unsubstituted linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted linear, branched or cyclic alkenyl group having 2 to 20 carbon atoms, or a substituted or unsubstituted linear, branched or cyclic alkynyl group having 2 to 20 carbon atoms. R2 is any one of a substituted or unsubstituted linear, branched or cyclic saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms, an amino group, a thiol group, and a halogen atom. n1 is an integer of 1 or more. 、 n2, n3, and n4 are integers equal to or greater than 0.

[0057] The present invention will be described in detail below, but the present invention is not limited thereto.

[0058] <Composition for forming resist underlayer film> The composition for forming a resist underlayer film of the present invention is a composition for forming a resist underlayer film, characterized by containing (A) a novolak resin having a repeating unit structure represented by the following general formula (I) and / or (II) and (B) an organic solvent: [ka] (In the above general formulas (I) and (II), Ar1 and Ar2 are each independently a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted heteroaryl group having 6 to 30 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms condensed or connected to an aliphatic ring or an ether ring, or a plurality of substituted or unsubstituted aryl groups having 6 to 30 carbon atoms connected to each other via a linear, branched or cyclic hydrocarbon group, an ether group or a carbonyl group; Ar1 ​​may be one type or a combination of multiple types in the same resin, and Ar2 may be one type or a combination of multiple types in the same resin. R1 is and a combination of at least two or more of them, which are a hydrogen atom, a substituted or unsubstituted linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted linear, branched or cyclic alkenyl group having 2 to 20 carbon atoms, or a substituted or unsubstituted linear, branched or cyclic alkynyl group having 2 to 20 carbon atoms. R2 is any one of a substituted or unsubstituted linear, branched or cyclic saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms, an amino group, a thiol group, and a halogen atom. n1 is an integer of 1 or more. 、 n2, n3, and n4 are integers equal to or greater than 0.

[0059] In the resist underlayer film forming composition of the present invention, the component (A) is a novolak resin, so that the main skeleton contains an aromatic ring, and the mechanical strength (also called processing resistance) for withstanding processing is excellent. Furthermore, by combining at least two or more types of R1, at least two types of repeating units having different OR1s are present in the same resin, and / or repeating units containing two or more types of OR1 groups are present. In this way, the steric hindrance of the substituent introduced via the ether structure can suppress dense packing between aromatic rings and dense crosslinking reactions, and the film obtained by curing the composition can be suppressed from becoming densified. By suppressing densification, the film obtained by curing the composition can exhibit excellent gas permeability. In this way, by appropriately selecting the main skeleton structure and the substituent structure, it is possible to achieve both the contradictory performances of processing resistance and gas permeability. In addition, by combining at least two or more types of R1, it is possible to suppress the crystallinity of the resin, suppress the densification of the film, and also impart thermal fluidity. Therefore, the composition for forming a resist underlayer film of the present invention can provide a resist underlayer film that is expected to have good processing resistance, excellent embedding ability and flatness, low film density, and good gas permeability.

[0060] According to the composition for forming a resist underlayer film of the present invention, a resist underlayer film that can be used in various pattern forming methods can be formed. For example, the resist underlayer film formed from the composition for forming a resist underlayer film of the present invention can be used as a resist underlayer film in a pattern forming method by a multilayer resist process, or as a resist underlayer film in a pattern forming method by an imprinting method, or can be used in other pattern forming methods. In particular, as described above, the resist underlayer film formed from the composition for forming a resist underlayer film of the present invention has good processing resistance, excellent embedding property and flatness, and further has low film density and good gas permeability. Therefore, according to the composition for forming a resist underlayer film of the present invention, a resist underlayer film that is very useful for nanoimprinting can be realized.

[0061] Hereinafter, each component of the composition for forming a resist underlayer film of the present invention will be described in more detail.

[0062] <(A) Novolac resin> In the above general formulas (I) and (II), R1 is a combination of at least two or more in the same resin, and is a hydrogen atom, a substituted or unsubstituted linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted linear, branched or cyclic alkenyl group having 2 to 20 carbon atoms, or a substituted or unsubstituted linear, branched or cyclic alkynyl group having 2 to 20 carbon atoms, and two or more can be used in combination depending on the properties to be imparted. For example, from the viewpoint of suppressing packing of aromatic rings and dense crosslinking reaction, it is preferable to use linear alkyl groups such as n-hexyl groups and n-octyl groups, branched alkyl groups such as neopentyl groups, cyclic alkyl groups such as methylcyclohexyl groups and methyladamantyl groups, and cyclic ether groups such as methyltetrahydrofuran, and from the viewpoint of maintaining processing resistance, it is more preferable to use cyclic alkyl groups or ether groups. In addition, from the viewpoint of thermosetting, it is preferable to contain unsaturated bonds.

[0063] In the above general formulas (I) and (II), specific examples of structures other than a hydrogen atom for R1 include, but are not limited to, the structures shown below. (* represents the bond to oxygen.)

[0064] [ka]

[0065] In the above formulas (I) and (II), at least one of R1 is a structure R selected from the group consisting of groups represented by the following formula (III-1): 1-1 It is preferable that: [ka] (In formula (III-1), * represents a bond to an oxygen atom.)

[0066] In the above general formulas (I) and (II), at least one of R1 is a structure R selected from the group consisting of groups represented by the above general formula (III-1). 1-1 If the composition has a cyclic structure, the processing resistance is not easily impaired, while the cyclic structure itself has a low density, and furthermore, the steric hindrance is large, so that the effect of preventing the aromatic rings from being closely adjacent to each other is large, and a film with a low film density can be provided. That is, according to the composition for forming a resist underlayer film of this preferred embodiment, a resist underlayer film that is excellent in processing resistance and can exhibit better gas permeability can be provided.

[0067] In the above formulas (I) and (II), R1 is a structure R selected from the group consisting of groups shown in the following (III-1): 1-1 and a structure R selected from the group consisting of groups represented by the following formula (III-2): 1-2 It is a combination of structure R 1-1 The ratio of a to R 1-2 When the ratio of a to b is taken as the ratio, it is preferable that the ratios a and b satisfy the relationships 1≦a≦99, 1≦b≦99, and a+b=100. [ka] (In formulas (III-1) and (III-2), * represents a bond to an oxygen atom.)

[0068] In the above general formulas (I) and (II), R1 is a structure R selected from the group consisting of groups represented by the above formula (III-1) from the viewpoints of maintaining processing resistance, reducing film density, and improving thermal fluidity. 1-1 From the viewpoint of curability, it is preferable that the structure R is selected from the group consisting of groups represented by the following formula (III-2): 1-2 Therefore, if the resin is not sufficiently hardened, the structure R 1-1 and structure R 1-2 It is preferable to select one or more of the following and use them in combination. 1-2 The hardening and structural R obtained by 1-1In order to balance the effects obtained by the above, it is more preferable that the ratio of the combination of the substituent structures of these two groups is a ratio that ensures the curability of the resin alone at the very least, and specifically, it is preferable that the relationships 1≦a≦99, 1≦b≦99, a+b=100 are satisfied, more preferably the relationships 10≦b≦90, a+b=100 are satisfied, and further preferably the relationships 10≦b≦50, a+b=100 are satisfied.

[0069] R1 may be a combination of at least two or more in the same resin, and n1 R1s in the same repeating unit structure may all be the same. By having at least two or more combinations of R1 in the same resin, the novolac resin contained in the composition for forming a resist underlayer film of the present invention can contain, for example, at least two repeating units in which OR1 is different from each other in the same resin. Alternatively, when n1 is 2 or more, the novolac resin contained in the composition for forming a resist underlayer film of the present invention can contain repeating units containing two or more OR1 groups. By having at least two or more combinations of R1 in the same resin, the thermal fluidity is improved, the flatness is improved, and the swelling (density reduction) after rework of the film obtained from the composition can be achieved.

[0070] In the above general formulas (I) and (II), Ar1 and Ar2 are each independently a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted heteroaryl group having 6 to 30 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms fused or connected to an aliphatic ring or ether ring, or a linear, branched or cyclic hydrocarbon group, an ether group or a plurality of substituted or unsubstituted aryl groups having 6 to 30 carbon atoms connected to each other via a carbonyl group, and from the viewpoint of processing resistance, it is preferable that the simple aromatic compound is benzene, naphthalene, anthracene, etc. Also, with regard to Ar1, from the viewpoint of reducing the film density, it is preferable that the compound has a structure in which an aryl group bonded or fused to a linear, branched or cyclic alkyl group or ether is combined, such as a spiroindane structure or a spiro ring structure, or that the compound has resveratrol or hematoxylin.

[0071] Ar1 may be one type or a combination of multiple types in the same resin, and Ar2 may be one type or a combination of multiple types in the same resin. By combining multiple types, it is possible to adjust the molecular weight during condensation, and further to improve the solubility and thermal fluidity of the condensate.

[0072] In the above general formulas (I) and (II), R2 is any of a substituted or unsubstituted linear, branched or cyclic saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms, an amino group, a thiol group, or a halogen atom, which can be selected according to the properties to be imparted. For example, from the viewpoint of thermal fluidity, it is preferable that it is a linear, branched or cyclic hydrocarbon group or a heteroalkyl group, and further, from the viewpoint of suppressing packing of aromatic rings while maintaining processing resistance, it is preferable that it is a cyclic hydrocarbon group. In addition, from the viewpoint of thermosetting, it is preferable that it contains an unsaturated bond, and from the viewpoint of increasing the hydrophobicity of the film, it is preferable that it contains a fluorine atom.

[0073] Specific examples of the core structure including Ar1, R2, and OR1 in the above general formulas (I) and (II) include, but are not limited to, the following structures. OR1 can be appropriately selected from the above specific examples.

[0074] [ka]

[0075] [ka]

[0076] [ka]

[0077] [ka]

[0078] [ka]

[0079] Specific examples of the core structure including Ar2, R2, and OR1 in the above general formula (II) include, but are not limited to, the following structures. In addition, OR1 can be appropriately selected from the above specific examples. (* is the bond to the trityl group.)

[0080] [ka]

[0081] In the above general formulas (I) and (II), Ar1 is preferably selected from the group consisting of structures represented by the following formula (Ar-1) from the viewpoints of raw material availability, reactivity, and reduction in film density. [ka]

[0082] In the above general formulas (I) and (II), if Ar1 is a benzene ring or a naphthalene ring, there are many types of monomers, and various physical properties can be tuned by selecting a substituent according to the required performance. For example, if you want to suppress packing, you can select an alkyl group such as a t-butyl group or a cyclohexyl group, or if you want to make the film hydrophobic, you can select a fluorine atom. In addition, all of the other structures shown in the above formula (Ar-1) have two benzene rings in one molecule, which are further bonded or condensed with a linear or cyclic alkyl group or ether group, so that they have a structure that can suppress packing between aromatic rings, and can suppress the film from becoming dense after baking. Therefore, it is possible to provide a resist underlayer film that exhibits good gas permeability and also has good flatness.

[0083] In addition, in the above general formula (II), Ar2 is preferably a benzene ring from the viewpoints of availability of raw materials and reactivity.

[0084] In the above formula (II), if Ar2 is a benzene ring, various raw materials with different substituents are available, so that the physical properties can be tuned to meet the required performance.

[0085] In the general formulas (I) and (II), n1 is an integer of 1 or more. 、 n2, n3, and n4 are integers of 0 or more. From the viewpoint of decreasing the film density and further increasing the thermal fluidity, n1 is more preferably 2 or more. From the viewpoint of polymerizability, n2 is preferably 0, and from the viewpoint of decreasing the film density and further increasing the thermal fluidity, it is preferably 1 to 2. Moreover, from the viewpoint of decreasing the film density and further increasing the thermal fluidity, n3 and n4 are preferably n3+n4=1 or more.

[0086] Furthermore, in the above formula (II), n3+n4 is more preferably an integer of 2 or more, and the following structure is a preferred specific structure of the core structure including Ar2, R2, and OR1. OR1 can be appropriately selected from the specific examples mentioned above. (* is the bond to the trityl group.)

[0087] [ka]

[0088] The composition for forming a resist underlayer film of the present invention may contain at least one of a novolac resin having a repeating unit structure represented by the above general formula (I) and a novolac resin having a repeating unit structure represented by the above general formula (II), and may contain either one of a novolac resin having a repeating unit structure represented by the above general formula (I) and a novolac resin having a repeating unit structure represented by the above general formula (II), or may contain both. In addition, it may contain a novolac resin having both a repeating unit structure represented by the above general formula (I) and a repeating unit structure represented by the above formula (II). In another aspect, the novolac resin contained in the composition for forming a resist underlayer film of the present invention may contain two or more of the above repeating unit structures in which R1 is different from each other.

[0089] <(A) Method for synthesizing novolac resin> The (A) novolak resin can be synthesized by carrying out a condensation reaction (STEP 1 shown below) using a hydroxyl group-containing derivative of Ar1 (X), a formaldehyde or benzaldehyde derivative containing Ar2 (Y), and a catalyst, and then etherifying the resulting condensate with an alkyl halide, alkyl tosylate, or alkyl mesylate (Z) or the like using a catalyst (STEP 2 shown below). (R1, R2, n1, n2, n3, and n4 are the same as above, X is a halogen group, a mesyl group, or a tosyl group, and two or more types of R1-X are used, but for convenience of explanation, only one type is described.)

[0090] [ka]

[0091] [ka]

[0092] The condensation reaction using the above-mentioned hydroxyl group-containing Ar1 derivative (X), formaldehyde or benzaldehyde derivative (Y), and a catalyst can usually be carried out without a solvent or in a solvent using an acid or a base as a catalyst at room temperature or under cooling or heating as necessary.

[0093] Examples of the solvent that can be used include alcohols such as methanol, ethanol, isopropyl alcohol, butanol, ethylene glycol, propylene glycol, diethylene glycol, glycerol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, and propylene glycol monomethyl ether; ethers such as diethyl ether, dibutyl ether, diethylene glycol diethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, and 1,4-dioxane; and chlorine-based solvents such as methylene chloride, chloroform, dichloroethane, and trichloroethylene. Examples of solvents include solvents such as hexane, heptane, benzene, toluene, xylene, cumene, etc., nitriles such as acetonitrile, ketones such as acetone, ethyl methyl ketone, isobutyl methyl ketone, etc., esters such as ethyl acetate, n-butyl acetate, propylene glycol methyl ether acetate, etc., lactones such as γ-butyrolactone, dimethyl sulfoxide, N,N-dimethylformamide, N-methyl-2-pyrrolidone, hexamethylphosphoric triamide, etc., and these can be used alone or in combination of two or more. These solvents can be used in an amount of, for example, 0 to 3000 parts by mass per 100 parts by mass of the reaction raw materials.

[0094] Examples of the acid catalyst that can be used include inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, and heteropolyacids; organic acids such as oxalic acid, trifluoroacetic acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, and trifluoromethanesulfonic acid; and Lewis acids such as aluminum trichloride, aluminum ethoxide, aluminum isopropoxide, boron trifluoride, boron trichloride, boron tribromide, tin tetrachloride, tin tetrabromide, dibutyltin dichloride, dibutyltin dimethoxide, dibutyltin oxide, titanium tetrachloride, titanium tetrabromide, titanium(IV) methoxide, titanium(IV) ethoxide, titanium(IV) isopropoxide, and titanium(IV) oxide. Examples of the base catalyst that can be used include inorganic bases such as sodium hydroxide, potassium hydroxide, barium hydroxide, sodium carbonate, sodium hydrogencarbonate, potassium carbonate, lithium hydride, sodium hydride, potassium hydride, and calcium hydride, alkyl metals such as methyllithium, n-butyllithium, methylmagnesium chloride, and ethylmagnesium bromide, alkoxides such as sodium methoxide, sodium ethoxide, and potassium t-butoxide, and organic bases such as triethylamine, diisopropylethylamine, N,N-dimethylaniline, pyridine, and 4-dimethylaminopyridine. The amount of the base catalyst used is in the range of 0.001 to 100% by weight, preferably 0.005 to 50% by weight, based on the raw material.

[0095] The reaction temperature is preferably from -50°C to the boiling point of the solvent, more preferably from room temperature to 130°C.

[0096] Condensation reaction methods include a method of charging a hydroxyl group-containing Ar1 derivative (X), a formaldehyde or benzaldehyde derivative (Y), and a catalyst all at once, a method of dropping a formaldehyde or benzaldehyde derivative (Y) or a solution of formaldehyde or benzaldehyde derivative (Y) dissolved in a reaction solvent in the presence of a derivative (X) and a catalyst, and a method of dropping a derivative (X) or a solution of derivative (X) dissolved in a reaction solvent in the presence of a catalyst. The amount of formaldehyde or benzaldehyde derivative (Y) used at this time is preferably 0.7 to 1.2 equivalents relative to the derivative (X), more preferably 0.8 to 1.05 equivalents. After the condensation reaction is completed, in order to remove unreacted raw materials, catalysts, etc. present in the system, the temperature of the reaction vessel is raised to 130 to 230°C and volatile matters are removed at about 1 to 50 mmHg, an appropriate poor solvent or water is added to reprecipitate the polymer, or the polymer is fractionated, and other methods can be used depending on the properties of the raw materials used and the reaction product obtained. In addition, a process can be added in which the obtained condensate is dissolved in an appropriate water-immiscible solvent such as methyl isobutyl ketone or ethyl acetate and washed with water.

[0097] The subsequent etherification can be carried out in a solvent or without a solvent using a base as a catalyst at room temperature or under cooling or heating as necessary. Examples of the solvent that can be used include alcohols such as methanol, ethanol, isopropyl alcohol, butanol, ethylene glycol, propylene glycol, diethylene glycol, glycerol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, and propylene glycol monomethyl ether, ethers such as diethyl ether, dibutyl ether, diethylene glycol diethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, and 1,4-dioxane, and chlorine-based solvents such as methylene chloride, chloroform, dichloroethane, and trichloroethylene. Examples of solvents include hydrocarbons such as hexane, heptane, benzene, toluene, xylene, and cumene; nitriles such as acetonitrile; ketones such as acetone, ethyl methyl ketone, and isobutyl methyl ketone; esters such as ethyl acetate, n-butyl acetate, and propylene glycol methyl ether acetate; lactones such as γ-butyrolactone; and aprotic polar solvents such as dimethyl sulfoxide, N,N-dimethylformamide, hexamethylphosphoric triamide, and N-methylpyrrolidone. These can be used alone or in combination of two or more.

[0098] These solvents can be used in the range of 0 to 2,000 parts by mass per 100 parts by mass of the reaction raw materials.

[0099] Examples of the base catalyst that can be used include inorganic bases such as sodium hydroxide, potassium hydroxide, barium hydroxide, sodium carbonate, sodium hydrogen carbonate, potassium carbonate, lithium hydride, sodium hydride, potassium hydride, and calcium hydride, alkyl metals such as methyllithium, n-butyllithium, methylmagnesium chloride, and ethylmagnesium bromide, alkoxides such as sodium methoxide, sodium ethoxide, and potassium t-butoxide, and organic bases such as triethylamine, diisopropylethylamine, N,N-dimethylaniline, pyridine, and 4-dimethylaminopyridine. The amount of the catalyst used is preferably 0.5 to 1.5 equivalents, more preferably 1.0 to 1.2 equivalents, relative to the equivalent amount of hydroxyl groups contained in the raw materials for the condensation reaction.

[0100] The reaction temperature is preferably from -50°C to the boiling point of the solvent, more preferably from room temperature to 130°C.

[0101] The reaction method of (STEP 2) includes a method of charging the above condensate, compound (Z) and a catalyst all at once, a method of dropping the above condensate and the catalyst, compound (Z) or a solution of compound (Z) dissolved in a reaction solvent, and a method of dropping a solution of the above condensate in a reaction solvent in the presence of compound (Z) and a catalyst. In addition, since the synthesis of the compound of the present invention uses a plurality of compounds (Z), the above condensate and the catalyst are used in the presence of the above condensate and the catalyst, and the compound (Z) with a large steric hindrance at the reaction site and low reactivity, such as bromomethylcyclohexane, is added dropwise first, and then matured, and the compound (Z) with a small steric hindrance at the reaction site and high reactivity, such as propargyl bromide, is added later, or a solution of high-boiling point (Z) such as bromomethylcyclohexane, mesyl or tosyl body, which cannot be removed under reduced pressure after the reaction, or a solution of the same dissolved in a reaction solvent is added dropwise first, and then matured, and a small excess of low-boiling point compound (Z) such as propargyl bromide or bromopropene, which can be removed under reduced pressure after the reaction, is added dropwise to increase the substitution rate. After the etherification is completed, in order to remove unreacted raw materials, catalysts, etc. present in the system, the temperature of the reaction vessel is raised to 130 to 230°C, and volatiles are removed at about 1 to 50 mmHg, or an appropriate poor solvent or water is added to reprecipitate the polymer, or a polymer is fractionated, and the like, depending on the properties of the reaction product obtained, can be used. Finally, a process may be added in which the obtained novolak resin is dissolved in a suitable water-immiscible solvent such as methyl isobutyl ketone or ethyl acetate, and then acid-washed with a suitable acid such as nitric acid or hydrochloric acid or washed with ultrapure water to remove metal species such as sodium or potassium.

[0102] Furthermore, the weight average molecular weight Mw of the novolak resin (A) obtained by, for example, the above-mentioned synthesis method, as calculated in terms of polystyrene, as determined by gel permutation chromatography, is preferably 2,000 to 8,000, more preferably 2,000 to 6,000, from the viewpoints of embeddability and suppression of sublimate.

[0103] When the weight average molecular weight Mw of the (A) novolak resin is 2000 to 8000, the amount of low molecular weight components that sublimate upon baking is reduced, so that poor film-forming properties can be suppressed and an underlayer film that does not impair embedding properties can be obtained. When the weight average molecular weight Mw is 2000 to 6000, the effect is even greater.

[0104] <(B) Organic solvent> The (B) usable organic solvent is not particularly limited as long as it dissolves the (A) novolak resin and, if contained, the optional components (C) surfactant, (D) crosslinking agent, (E) thermally decomposable resin, (F) acid generator (e.g., a thermal acid generator), and other additives, which are described below.

[0105] Specifically, the organic solvents described in paragraphs

[0091] to

[0092] of JP 2007-199653 A can be added. More specifically, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, 2-heptanone, cyclopentanone, cyclohexanone, γ-butyrolactone, or a mixture containing one or more of these is preferably used.

[0106] The amount of the organic solvent to be added is preferably within a range of 200 to 10,000 parts, and more preferably 250 to 5,000 parts, based on 100 parts by mass of the novolak resin (A).

[0107] In addition, in the composition for forming a resist underlayer film of the present invention, the (B) organic solvent may be a mixture of one or more organic solvents having a boiling point of less than 180°C and one or more organic solvents having a boiling point of 180°C or higher ((B2) high boiling point solvent).

[0108] The (B2) high boiling point solvent is not particularly limited as long as it can dissolve each component of the composition for forming a resist underlayer film of the present invention, and may be, for example, a hydrocarbon, an alcohol, a ketone, an ester, an ether, or a chlorine-based solvent. Specific examples include 1-octanol, 2-ethylhexanol, 1-nonanol, 1-decanol, 1-undecanol, ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol, 2-ethyl-1,3-Hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, glycerin, n-nonyl acetate, monohexyl ether, ethylene glycol mono-2-ethylhexyl ether, ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, diethylene glycol monoethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol monoisobutyl ether, diethylene glycol monohexyl ether, diethylene glycol monophenyl ether, diethylene glycol monobenzyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol butyl methyl ether, triethylene glycol dimethyl ether, triethylene glycol monomethyl ether, triethylene glycol-n-butyl ether, triethylene glycol butyl methyl ether, tetraethylene glycol dimethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-n-butyl ether, tripropylene glycol dimethyl ether, tripropylene glycol monomethyl ether, tripropylene glycol mono-n-propyl ether, tripropylene glycol mono-n-butyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, triacetin, propylene glycol diacetate, dipropylene glycol methyl-n-propyl ether, dipropylene glycol methyl ether acetate, 1,4-butanediol diacetate, 1,3-butylene glycol diacetate, 1,Examples of the diethyl ester include 6-hexanediol diacetate, triethylene glycol diacetate, γ-butyrolactone, methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, dihexyl malonate, diethyl succinate, dipropyl succinate, dibutyl succinate, dihexyl succinate, dimethyl adipate, diethyl adipate, and dibutyl adipate. These may be used alone or in combination.

[0109] The high boiling point solvent may be appropriately selected from the above-mentioned solvents according to the temperature at which the resist underlayer film forming composition of the present invention is heat-treated. The boiling point of the high boiling point solvent is preferably 180°C to 300°C, more preferably 200°C to 300°C. If the solvent has such a boiling point, there is no risk of the solvent volatilizing too quickly during baking (heat treatment), so that sufficient thermal fluidity can be obtained during film formation, and it is believed that a resist underlayer film having excellent filling / flattening properties can be formed. In addition, if the solvent has such a boiling point, there is no risk of the solvent remaining in the film without volatilizing after baking, so there is no risk of adversely affecting the film properties such as filling properties.

[0110] When a high boiling point solvent is used, the blending amount is preferably 1 to 30 parts by mass per 100 parts by mass of an organic solvent having a boiling point of less than 180° C. Such a blending amount is preferable because it can impart sufficient thermal fluidity during baking and does not remain in the film, leading to deterioration of film properties such as embedding characteristics.

[0111] <Optional ingredients> The composition for forming a resist underlayer film of the present invention may further contain optional components other than the (A) novolak resin and the (B) organic solvent. The optional components will be described below.

[0112] <(C) Surfactant> The composition of the present invention may contain a surfactant (C). A surfactant (C) can be added to the composition for forming a resist underlayer film of the present invention in order to improve the coatability in spin coating.

[0113] As the surfactant, for example, those described in

[0142] to

[0147] of JP-A-2009-269953 can be used. When a surfactant is added, the amount of the surfactant added is preferably 0.01 to 10 parts, more preferably 0.05 to 5 parts, based on 100 parts by mass of the novolak resin (A).

[0114] <(D) Crosslinking agent> The composition of the present invention may contain a crosslinking agent (D). The crosslinking agent (D) promotes crosslinking within the film, and because of its structure containing aromatic rings, it is closely adjacent to the novolac resin (A), which has the effect of increasing the density of the film. Therefore, there are fewer holes through which the solvent can penetrate, and swelling of the film after rework is suppressed. Therefore, the crosslinking agent can be added as a crosslinking promoter and also as a film swelling suppressor.

[0115] The (D) crosslinking agent is not particularly limited, and various known crosslinking agents can be widely used. Examples include melamine-based crosslinking agents, acrylate-based crosslinking agents, glycoluril-based crosslinking agents, benzoguanamine-based crosslinking agents, urea-based crosslinking agents, β-hydroxyalkylamide-based crosslinking agents, isocyanurate-based crosslinking agents, aziridine-based crosslinking agents, oxazoline-based crosslinking agents, epoxy-based crosslinking agents, and phenol-based crosslinking agents (e.g., methylol or alkoxymethyl-type crosslinking agents of polynuclear phenols). The content of the (D) crosslinking agent is preferably 5 to 50 parts by mass, more preferably 10 to 40 parts by mass, relative to 100 parts by mass of the (A) novolac resin.

[0116] Specific examples of the melamine-based crosslinking agent include hexamethoxymethylated melamine, hexabutoxymethylated melamine, alkoxy- and / or hydroxy-substituted products thereof, and partial self-condensates thereof.

[0117] A specific example of the acrylate crosslinking agent is dipentaerythritol hexaacrylate.

[0118] Specific examples of glycoluril crosslinking agents include tetramethoxymethylated glycoluril, tetrabutoxymethylated glycoluril, alkoxy and / or hydroxy substituted products thereof, and partial self-condensates thereof.

[0119] Specific examples of benzoguanamine-based crosslinking agents include tetramethoxymethylated benzoguanamine, tetrabutoxymethylated benzoguanamine, alkoxy- and / or hydroxy-substituted products thereof, and partial self-condensates thereof.

[0120] Specific examples of the urea-based crosslinking agent include dimethoxymethylated dimethoxyethyleneurea, its alkoxy and / or hydroxyl substituted derivatives, and partial self-condensates thereof.

[0121] A specific example of the β-hydroxyalkylamide crosslinking agent is N,N,N',N'-tetra(2-hydroxyethyl)adipamide.

[0122] Specific examples of the isocyanurate crosslinking agent include triglycidyl isocyanurate and triallyl isocyanurate.

[0123] Specific examples of the aziridine crosslinking agent include 4,4'-bis(ethyleneiminocarbonylamino)diphenylmethane and 2,2-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate].

[0124] Specific examples of the oxazoline crosslinking agent include 2,2'-isopropylidenebis(4-benzyl-2-oxazoline), 2,2'-isopropylidenebis(4-phenyl-2-oxazoline), 2,2'-isopropylidenebis(4-phenyl-2-oxazoline), 2,2'-methylenebis-4,5-diphenyl-2-oxazoline, 2,2'-methylenebis-4-phenyl-2-oxazoline, 2,2'-methylenebis-4-tertbutyl-2-oxazoline, 2,2'-bis(2-oxazoline), 1,3-phenylenebis(2-oxazoline), 1,4-phenylenebis(2-oxazoline), and 2-isopropenyloxazoline copolymer.

[0125] Specific examples of epoxy crosslinking agents include diglycidyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,4-cyclohexanedimethanol diglycidyl ether, poly(glycidyl methacrylate), trimethylolethane triglycidyl ether, trimethylolpropane triglycidyl ether, and pentaerythritol tetraglycidyl ether.

[0126] Specific examples of polynuclear phenol-based crosslinking agents include compounds represented by the following general formula (XL-1).

[0127] [ka] (In the formula, L is a single bond or a q-valent hydrocarbon group having 1 to 20 carbon atoms. R3 is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. q is an integer of 1 to 5.)

[0128] L is a single bond or a q-valent hydrocarbon group having 1 to 20 carbon atoms. q is an integer of 1 to 5, and is more preferably 2 or 3. Specific examples of L include methane, ethane, propane, butane, isobutane, pentane, cyclopentane, hexane, cyclohexane, methylpentane, methylcyclohexane, dimethylcyclohexane, trimethylcyclohexane, benzene, toluene, xylene, ethylbenzene, ethylisopropylbenzene, diisopropylbenzene, methylnaphthalene, ethylnaphthalene, and eicosane from which q hydrogen atoms have been removed. R3 is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. Specific examples of the alkyl group having 1 to 20 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a pentyl group, an isopentyl group, a hexyl group, an octyl group, an ethylhexyl group, a decyl group, and an eicosanyl group, and a hydrogen atom or a methyl group is preferred.

[0129] Specific examples of the compound represented by the above general formula (XL-1) include the following compounds. Among these, from the viewpoint of improving the curability and thickness uniformity of the organic film, hexamethoxymethylated triphenolmethane, triphenolethane, 1,1,1-tris(4-hydroxyphenyl)ethane, and tris(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene are preferred. R3 is the same as above.

[0130] [ka]

[0131] [ka]

[0132] <(E) Thermally decomposable resin> The composition for forming a resist underlayer film of the present invention may further contain (E) a thermally decomposable resin from the viewpoint of reducing the film density.

[0133] As the (E) thermally decomposable resin, a liquid additive having a polyethylene glycol or polypropylene glycol structure, or a thermally decomposable polymer (resin) having a weight loss rate of 40% or more by mass between 30° C. and 250° C. and a weight average molecular weight of 300 to 200,000 is preferably used. This thermally decomposable polymer preferably contains a repeating unit having an acetal structure represented by the following general formulas (DP1), (DP1a) to (DP3a).

[0134] [ka] (In the formula, R 1 is a hydrogen atom or an optionally substituted saturated or unsaturated monovalent organic group having 1 to 30 carbon atoms. W is a saturated or unsaturated divalent organic group having 2 to 30 carbon atoms.

[0135] [ka] (In formulas (DP1a) to (DP3a), R 1a is an alkyl group having 1 to 4 carbon atoms. a R is a saturated or unsaturated divalent hydrocarbon group having 4 to 10 carbon atoms, which may have an ether bond. b1 are each independently, -W a R is —OH or a saturated or unsaturated monovalent organic group having 1 to 30 carbon atoms which may be substituted. 1c R is a hydrogen atom, or an optionally substituted aryl group having 6 to 20 carbon atoms or a optionally substituted heteroaryl group having 4 to 20 carbon atoms. c1 each independently represents an alkyl group having 1 to 4 carbon atoms, or -W a -OH. n represents the average number of repeating units and is 3 to 500.

[0136] Specific examples of the thermally decomposable resin include, but are not limited to, those shown below.

[0137] [ka]

[0138] [ka]

[0139] [ka]

[0140] [ka] (n represents the average number of repeating units and is 3 to 500).

[0141] When the (E) thermally decomposable resin is added, the amount added is preferably 0.05 to 50 parts, more preferably 0.1 to 10 parts, based on 100 parts by mass of the (A) novolak resin.

[0142] <(F) Acid Generator> In the resist underlayer film forming composition of the present invention, an acid generator can be added to further promote the curing reaction of the novolac resin (A). The acid generator may be one that generates an acid by thermal decomposition (thermal acid generator) or one that generates an acid by light irradiation (photoacid generator), and either one may be added. Specifically, the materials described in paragraphs

[0061] to

[0085] of JP-A-2007-199653 may be added, but are not limited thereto.

[0143] The acid generator may be used alone or in combination of two or more. When an acid generator is added, the amount of the acid generator is preferably 0.05 to 50 parts, more preferably 0.1 to 10 parts, based on 100 parts by mass of the novolak resin (A).

[0144] [Film density properties] The resist underlayer film forming composition of the present invention may be, for example, one in which the resist underlayer film forming composition is applied to a substrate to obtain a coating film, the coating film is baked at 180°C for 60 seconds, and then additionally baked at 350°C for 60 seconds, the thickness of the coating film after which is represented by FT-1, OK73 thinner obtained by mixing propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate in a ratio of 7:3 is dispensed onto the coating film after additional baking, and then the coating film is left for 30 seconds, and then the coating film is spin-dried, and then the coating film is baked at 100°C for 60 seconds to evaporate the OK73 thinner, and the thickness of the coating film after which is represented by FT-2, and the relationship between the thickness of the coating film and the thickness of the coating film can be 100.5<{(FT-2) / (FT-1)}×100.

[0145] {(FT-2) / (FT-1)}×100 being greater than 100.5 means that the film is swollen after rework, and that the film has become porous with fine pores through which the solvent can penetrate. When a dense curing reaction occurs as in normal resins, there are no gaps through which the solvent can penetrate, so such swelling does not occur, and the film thickness after rework does not become extremely thick. Based on the above, the inventors of the present invention considered that the composition of the present invention is a porous film through which the solvent can penetrate, and that the film density is low, and that gas also seeps into the film and penetrates therethrough, just like the solvent.

[0146] If the ratio is 100.5<{(FT-2) / (FT-1)}×100, the film after firing will be porous with many pores that allow the OK73 thinner to soak in, and the larger the value, the more porous and low-density the film will be. Therefore, when considering gas permeability, it is more preferable that the ratio is 101<{(FT-2) / (FT-1)}×100.

[0147] When the composition further contains a crosslinking agent (D), it is preferable that the composition satisfies 100<{(FT-2) / (FT-1)}×100<101. As mentioned above, the crosslinking agent (D) has the effect of increasing the density of the film. Therefore, there are fewer holes through which the solvent can penetrate, and the swelling of the film after rework is suppressed. Therefore, the crosslinking agent can be added as a crosslinking promoter and also as a swelling suppressor of the film.

[0148] When (E) a thermally decomposable resin is further included, it is preferable that 101<{(FT-2) / (FT-1)}×100. By including (E) a thermally decomposable resin, the thermally decomposable resin decomposes during baking and sublimes from within the film, thereby forming minute pores within the film. This increases the swelling of the film after rework, making it possible to increase the porosity of the film and reduce the film density.

[0149] When the composition further contains both the crosslinking agent (D) and the thermally decomposable resin (E), it is also preferable that the relationship satisfies 100<{(FT-2) / (FT-1)}×100.

[0150] (D) Crosslinking agent and (E) thermally decomposable resin have opposing effects as film density adjusters. Therefore, when using both at the same time, it is sufficient to confirm only the hardening of the film. When comparing the difference in film thickness before and after rework, it is sufficient if (FT-2)>(FT-1).

[0151] Hereinafter, a method for producing a resist underlayer film, a method for forming a pattern, and a method for producing a semiconductor device using the resist underlayer film forming composition according to the present invention will be described.

[0152] [Method of manufacturing resist underlayer film] The method for producing a resist underlayer film of the present invention comprises the steps of: Applying the composition for forming a resist underlayer film of the present invention onto a semiconductor substrate to obtain a coating film; baking the coating film to obtain a resist underlayer film. Includes.

[0153] Semiconductor substrates, e.g., substrates used in the manufacture of semiconductor devices, include, for example, silicon wafer substrates, silicon / silicon dioxide coated substrates, silicon nitride substrates, glass substrates, ITO substrates, polyimide substrates, and low dielectric constant material (low-k material) coated substrates.

[0154] The resist underlayer film forming composition of the present invention is applied onto this semiconductor substrate by an appropriate application method such as using a spinner or a coater to obtain a coating film.

[0155] Thereafter, the coating film is baked to form a resist underlayer film.

[0156] The firing conditions are appropriately selected from a firing temperature of 80°C to 400°C and a firing time of 0.3 to 60 minutes. Preferably, the firing temperature is 150°C to 350°C and the firing time is 0.5 to 2 minutes, and more preferably, a two-stage firing is performed by firing at a firing temperature of 100°C to 200°C for 0.5 to 2 minutes, followed by additional firing at 200°C to 350°C for 0.5 to 2 minutes. Here, the film thickness of the lower layer film formed is, for example, 10 to 1500 nm, and more preferably 1000 to 500. Furthermore, if a quartz substrate is used as the substrate, a replica (mold replica) of the quartz imprint mold can be produced.

[0157] Also, an adhesion layer and / or a silicone layer containing 99% by mass or less or 50% by mass or less of Si can be formed by coating or vapor deposition on the resist underlayer film formed as described above. For example, in addition to the adhesion layer described in JP-A-2013-202982 and JP-A-5827180 and the method of forming a silicon-containing resist underlayer film (inorganic resist underlayer film) forming composition described in WO2009 / 104552A1 by spin coating, a Si-based inorganic material film can be formed by a CVD method or the like.

[0158] In addition, as described above, the resist underlayer film forming composition according to the present invention can form an underlayer film exhibiting improved flatness. For example, the resist underlayer film forming composition according to the present invention can be applied onto a semiconductor substrate having a portion with a step and a portion without a step (so-called stepped substrate) to obtain a coating film, and the coating film can be baked to form a resist underlayer film in which the step between the portion with a step and the portion without a step is within the range of 3 to 100 nm.

[0159] [Pattern formation method] The pattern forming method according to the present invention comprises the steps of: forming a resist underlayer film on a semiconductor substrate from the composition for forming a resist underlayer film of the present invention; forming a curable composition film on the resist underlayer film; contacting the curable composition film with a mold; a step of irradiating the curable composition film with light or an electron beam to form a cured film; separating the cured film from the mold; Includes.

[0160] This pattern formation method is called an imprint method using a mold. The imprint method may be a nanoimprint method. According to the pattern formation method by the imprint method of the present invention, a resist underlayer film having good processing resistance, excellent embedding property and flatness, and further having low film density and good gas permeability can be used. Therefore, according to the pattern formation method by the imprint method of the present invention, air bubbles generated when the mold is pressed against the curable composition film can be quickly removed, and a fine pattern can be formed.

[0161] Each step will be described in more detail below.

[0162] <Step of forming resist underlayer film> In this step, for example, a resist underlayer film can be formed on a semiconductor substrate from the composition for forming a resist underlayer film of the present invention by the method for producing a resist underlayer film of the present invention described above.

[0163] <Step of forming a curable composition film> This step is a step of forming a curable composition film on the resist underlayer film.

[0164] The composition of the curable composition film formed on the resist underlayer film is not particularly limited as long as it is sensitive to the light used for exposure. Both negative photoresists and positive photoresists can be used. There are positive photoresists made of novolac resin and 1,2-naphthoquinone diazide sulfonic acid ester, chemically amplified photoresists made of a binder having a group that decomposes with acid to increase the alkaline dissolution rate and a photoacid generator, chemically amplified photoresists made of a low molecular compound that decomposes with acid to increase the alkaline dissolution rate of the photoresist, an alkali-soluble binder, and a photoacid generator, and chemically amplified photoresists made of a binder having a group that decomposes with acid to increase the alkaline dissolution rate, a low molecular compound that decomposes with acid to increase the alkaline dissolution rate of the photoresist, and a photoacid generator. Examples of such photoresists include APEX-E (trade name) manufactured by Shipley, PAR710 (trade name) manufactured by Sumitomo Chemical Co., Ltd., and SEPR430 (trade name) manufactured by Shin-Etsu Chemical Co., Ltd. Further, there can be mentioned fluorine-containing polymer photoresists as described in, for example, Proc. SPIE, Vol. 3999, 330-334 (2000), Proc. SPIE, Vol. 3999, 357-364 (2000), and Proc. SPIE, Vol. 3999, 365-374 (2000).

[0165] [Method of applying the curable composition] Examples of methods for applying the curable composition include inkjet printing, dip coating, air knife coating, curtain coating, wire bar coating, gravure coating, extrusion coating, spin coating, and slit scanning. Inkjet printing is suitable for applying the curable composition as droplets, and spin coating is suitable for coating the curable composition. In this step, an adhesion layer and / or a silicone layer containing 99% by mass or less or 50% by mass or less of Si may be formed on the nanoimprint resist underlayer film by coating or vapor deposition, and the curable composition may be applied thereon.

[0166] In the step of forming the curable composition film, an adhesion layer and / or a silicone layer containing 99 mass % or less of Si can also be formed on the resist underlayer film by coating or vapor deposition.

[0167] By forming an adhesion layer, it is possible to sufficiently suppress pattern peeling in the subsequent mold separation process. In addition, by forming a silicone layer containing 99 mass % or less of Si, it is possible to adjust the optical properties of the film, enabling reflection control, etc.

[0168] <Step of bringing the curable composition film into contact with the mold> In this step, the curable composition film is brought into contact with a mold. For example, when the liquid curable composition film is brought into contact with a mold having a prototype pattern for transferring a pattern shape, a liquid film is formed in which the curable composition fills the recesses of the fine pattern on the mold surface.

[0169] Considering the process of irradiating light or electron beams described later, it is recommended to use a mold having a light-transmitting material as a substrate. Specifically, the mold substrate is preferably glass, quartz, light-transmitting resin such as PMMA or polycarbonate resin, transparent metal deposition film, flexible film such as polydimethylsiloxane, photocured film, metal film, etc. The mold substrate is more preferably quartz because of its small thermal expansion coefficient and small pattern distortion.

[0170] The fine pattern on the surface of the mold preferably has a pattern height of 4 nm or more and 200 nm or less. A certain pattern height is necessary to increase the processing accuracy of the substrate, but the lower the pattern height, the lower the force required to peel the mold from the cured film in the process of separating the cured film and the mold described below, and the fewer defects remaining on the mask side after the resist pattern is torn off. Taking these factors into consideration, it is recommended to select and adopt a pattern height with an appropriate balance.

[0171] In addition, when the mold is peeled off, the elastic deformation of the resist pattern due to the impact can cause adjacent resist patterns to come into contact with each other, resulting in adhesion or damage to the resist patterns. This can sometimes be avoided by making the pattern height approximately twice the pattern width (aspect ratio 2 or less).

[0172] In order to improve the releasability between the curable composition and the surface of the mold, the mold may be subjected to a surface treatment in advance. As a method of surface treatment, a method of applying a release agent to the surface of the mold to form a release agent layer may be mentioned. As the release agent, a silicone-based release agent, a fluorine-based release agent, a hydrocarbon-based release agent, a polyethylene-based release agent, a polypropylene-based release agent, a paraffin-based release agent, a montan-based release agent, a carnauba-based release agent, etc. may be mentioned. Fluorine-based and hydrocarbon-based release agents are preferable. As a commercially available product, for example, Optool (registered trademark) DSX manufactured by Daikin Industries, Ltd. may be mentioned. The release agent may be used alone or in combination of two or more kinds.

[0173] In this step, the pressure applied to the curable composition when the mold and the curable composition are brought into contact with each other is not particularly limited. A pressure of 0 MPa or more and 100 MPa or less is recommended. The pressure is preferably 0 MPa or more and 50 MPa or less, 30 MPa or less, or 20 MPa or less.

[0174] If the pre-spreading of the droplets of the curable composition has progressed in the previous step (the step of applying the curable composition), the spreading of the curable composition in this step is completed quickly. As a result, the time for contacting the mold with the curable composition can be shortened. The contact time is not particularly limited, but is preferably 0.1 seconds or more and 600 seconds or less, 3 seconds or less, or 1 second or less. If the contact time is too short, the spreading and filling may be insufficient, and a defect called an unfilled defect may occur.

[0175] This step can be carried out under any of the conditions of air atmosphere, reduced pressure atmosphere, and inert gas atmosphere, but is preferably carried out under a pressure of 0.0001 atm or more and 10 atm or less. In order to prevent the influence of oxygen and moisture on the curing reaction, it is recommended to carry out the step under a reduced pressure atmosphere or in an inert gas atmosphere. Specific examples of inert gases that can be used to create an inert gas atmosphere include nitrogen, carbon dioxide, helium, argon, CFC, HCFC, HFC, and mixed gases thereof.

[0176] This step may be performed under an atmosphere containing a condensable gas (hereinafter referred to as a "condensable gas atmosphere"). In this specification, the condensable gas refers to a gas that is condensed and liquefied by the capillary pressure generated when the gas is filled into the recesses of the fine pattern formed on the mold and the gap between the mold and the substrate together with the curable composition. The condensable gas exists as a gas in the atmosphere before the curable composition comes into contact with the mold in this step. When this step is performed under a condensable gas atmosphere, the gas filled into the recesses of the fine pattern is liquefied by the capillary pressure generated by the curable composition, and the bubbles disappear, resulting in excellent filling properties. The condensable gas may be dissolved in the curable composition.

[0177] The boiling point of the condensable gas is not limited as long as it is equal to or lower than the atmospheric temperature in this step, but is preferably -10°C or higher, or +10°C or higher and +23°C or lower.

[0178] The vapor pressure of the condensable gas at the atmospheric temperature in this step is not particularly limited as long as it is equal to or lower than the mold pressure, and is preferably in the range of 0.1 MPa to 0.4 MPa.

[0179] Specific examples of condensable gases include chlorofluorocarbons (CFCs) such as trichlorofluoromethane, fluorocarbons (FCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs) such as 1,1,1,3,3-pentafluoropropane (CHF2CH2CF3, HFC-245fa, PFP), and hydrofluoroethers (HFEs) such as pentafluoroethyl methyl ether (CF3CF2OCH3, HFE-245mc).

[0180] The condensable gas may be used alone or in combination of two or more. The condensable gas may be used in combination with a non-condensable gas such as air, nitrogen, carbon dioxide, helium, argon, etc. Air and helium are preferred as non-condensable gases to be mixed with the condensable gas.

[0181] <Step of irradiating the curable composition film with light or electron beam to form a cured film> In this step, the curable composition film is irradiated with light or an electron beam to form a cured film. That is, the curable composition film filled in the fine pattern of the mold is irradiated with light or an electron beam through the mold, and the curable composition filled in the fine pattern of the mold is cured in that state to form a cured film having a pattern shape.

[0182] The light or electron beam is selected according to the sensitivity wavelength of the curable composition. Specifically, ultraviolet light, X-rays, electron beams, etc. having a wavelength of 150 nm or more and 400 nm or less can be appropriately selected and used. Examples of light or electron beam light sources include high pressure mercury lamps, ultra-high pressure mercury lamps, low pressure mercury lamps, Deep-UV lamps, carbon arc lamps, chemical lamps, metal halide lamps, xenon lamps, KrF excimer lasers, ArF excimer lasers, F2 excimer lasers, etc. The number of light sources may be one or more. Irradiation may be performed on the entire curable composition filled in the fine pattern of the mold, or only on a partial area. Light irradiation may be performed intermittently multiple times on the entire area on the substrate, or may be continuously irradiated on the entire area. In addition, a first irradiation may be performed on a partial area on the substrate, and a second irradiation may be performed on an area different from the partial area.

[0183] The cured film thus obtained preferably has a pattern with a size of 1 nm or more, or 10 nm or more, and 10 mm or less, or 100 μm or less.

[0184] <Step of separating the cured film from the mold> In this step, the cured film is separated from the mold. The patterned cured film is separated from the mold to obtain a free-standing cured film having a pattern that is a reverse pattern of the fine pattern formed on the mold.

[0185] The method for separating the cured film having a pattern shape from the mold is not particularly limited as long as it is a means for moving the cured film and the mold in a direction in which they are relatively separated from each other, as long as a part of the cured film having a pattern shape is not physically damaged, and various conditions are also not particularly limited. For example, the substrate may be fixed and the mold may be moved away from the substrate to be peeled off, or the mold may be fixed and the substrate may be moved away from the mold to be peeled off. Alternatively, the substrate and the mold may be pulled and moved in opposite directions to be peeled off.

[0186] In addition, when the above-mentioned step of contacting the curable composition with the mold is carried out in a condensable gas atmosphere, when the cured film is separated from the mold in this step, the pressure at the interface where the cured film and the mold are in contact with each other decreases, and the condensable gas evaporates, which makes it possible to reduce the release force required to separate the cured film from the mold.

[0187] By the above steps, a cured film having a desired concave-convex pattern shape derived from the concave-convex shape of the mold at desired positions can be prepared.

[0188] Although the pattern formation method using the imprint method has been described above, the resist underlayer film obtained from the composition for forming a resist underlayer film of the present invention is not limited to the pattern formation method using the imprint method, and can also be used, for example, as a resist underlayer film in a pattern formation method by a multilayer resist process.

[0189] [Method of manufacturing semiconductor device] A method for manufacturing a semiconductor device according to a first aspect of the present invention includes the steps of: forming a resist underlayer film on a semiconductor substrate from the composition for forming a resist underlayer film of the present invention; forming a resist film on the resist underlayer film; a step of irradiating the resist film with light or an electron beam, and then developing the resist film to form a resist pattern; a step of etching the resist underlayer film using the formed resist pattern as a mask to obtain a patterned underlayer film; processing the semiconductor substrate using the patterned underlayer film as a mask; Includes.

[0190] Further, a method for manufacturing a semiconductor device according to a second aspect of the present invention includes the steps of: forming a resist underlayer film on a semiconductor substrate from the composition for forming a resist underlayer film of the present invention; forming a hard mask on the resist underlayer film; further forming a resist film on the hard mask; a step of irradiating the resist film with light or an electron beam, and then developing the resist film to form a resist pattern; Etching the hard mask using the formed resist pattern as a mask to obtain a patterned hard mask; Etching the underlayer film using the patterned hard mask as a mask to obtain a patterned resist underlayer film; processing the semiconductor substrate using the patterned resist underlayer film as a mask; Includes.

[0191] The first embodiment of the method for manufacturing a semiconductor device and the second embodiment of the method for manufacturing a semiconductor manufacturing apparatus will be described in detail below.

[0192] <First aspect> [Step of forming a resist underlayer film on a semiconductor substrate from the composition for forming a resist underlayer film of the present invention] In this step, for example, the resist underlayer film can be formed by the method for producing the resist underlayer film of the present invention described above.

[0193] [Step of forming a resist film on the resist underlayer film] Next, a step of forming a resist film on the resist underlayer film is performed.

[0194] The material of the resist film is not particularly limited as long as it is a resist material used in a multi-layer resist method.

[0195] [A process of forming a resist pattern by irradiating a resist film with light or an electron beam and then developing the resist film] Next, the resist film thus formed is irradiated with light or an electron beam, and then developed to form a resist pattern.

[0196] The light or electron beam to be irradiated can be appropriately selected depending on the properties of the resist film. The development method is not particularly limited as long as it is a method used in a multi-layer resist method.

[0197] [Step of etching the resist underlayer film using the formed resist pattern as a mask to obtain a patterned underlayer film] Next, the resist underlayer film is etched using the previously formed resist pattern as a protective film.

[0198] In this step, the etching is preferably performed under conditions that allow the resist underlayer film to be etched more easily than the resist film. For example, when the resist film contains a large amount of silicon atoms, the resist film is difficult to remove by dry etching with an oxygen-based gas, and the resist underlayer film is preferentially etched. Therefore, dry etching with an oxygen-based gas is preferably performed.

[0199] This process makes it possible to obtain a patterned underlayer film.

[0200] [Processing the semiconductor substrate using the patterned underlayer film as a mask] Next, a process is carried out in which the semiconductor substrate is processed using the patterned underlayer film as a mask.

[0201] The semiconductor substrate is preferably processed by dry etching using a fluorine-based gas.

[0202] Examples of fluorine-based gases include tetrafluoromethane (CF4), perfluorocyclobutane (C4F8), perfluoropropane (C3F8), trifluoromethane, and difluoromethane (CH2F2).

[0203] <Second aspect> The second embodiment differs from the first embodiment in that a hard mask is formed on the resist underlayer film, the hard mask is etched using the resist pattern as a mask, and the resist underlayer film is etched using the patterned hard mask. The second embodiment will be described below, focusing on the differences from the first embodiment.

[0204] The material of the hard mask is not particularly limited as long as it is a hard mask material that can be used in a multi-layer resist process.

[0205] For example, dry etching can be used for etching the inorganic hard mask. For example, tetrafluoromethane (CF4), perfluorocyclobutane (C4F8), perfluoropropane (C3F8), trifluoromethane, carbon monoxide, argon, oxygen, nitrogen, sulfur hexafluoride, difluoromethane, nitrogen trifluoride, chlorine trifluoride, chlorine, trichloroborane, dichloroborane, and other gases can be used for dry etching the inorganic hard mask. For example, halogen-based gases are used for dry etching the inorganic hard mask, and fluorine-based gases are more preferred. Examples of fluorine-based gases include tetrafluoromethane (CF4), perfluorocyclobutane (C4F8), perfluoropropane (C3F8), trifluoromethane, and difluoromethane (CH2F2).

[0206] As in the second embodiment, in the present invention, after forming a resist underlayer film on a substrate, a hard mask is formed thereon, and a resist film is further coated thereon, thereby narrowing the pattern width of the resist film, and even if the resist film is thinly coated to prevent pattern collapse, it is possible to process the substrate by selecting an appropriate etching gas. For example, a fluorine-based gas that has a sufficiently high etching rate for the resist film can be used as an etching gas to process the resist underlayer film, a fluorine-based gas that has a sufficiently high etching rate for the hard mask can be used as an etching gas to process the substrate, and an oxygen-based gas that has a sufficiently high etching rate for the resist underlayer film can be used as an etching gas to process the substrate.

[0207] In both the first and second embodiments, an organic antireflective film can be formed on the resist underlayer film before the formation of a resist film or a hard mask. There is no particular limitation on the antireflective film composition used therein, and any composition commonly used in the lithography process can be selected and used, and the antireflective film can be formed by a commonly used method, such as coating with a spinner or coater and baking.

[0208] The resist underlayer film formed by the resist underlayer film forming composition of the present invention may also absorb light depending on the wavelength of the light used in the lithography process. In such a case, it can function as an anti-reflection film having the effect of preventing light reflected from the substrate. Furthermore, in the first embodiment, the underlayer film formed by the resist underlayer film forming composition of the present invention can also function as a hard mask. The underlayer film of the present invention can also be used as a layer for preventing the interaction between the substrate and the resist film, a layer having a function of preventing the adverse effect on the substrate of the material used in the resist film or the substance generated during exposure of the resist film, a layer having a function of preventing the diffusion of the substance generated from the substrate during heating and baking into the resist film, and a barrier layer for reducing the poisoning effect of the resist film due to the dielectric layer of the semiconductor substrate.

[0209] In addition, the underlayer film formed from the resist underlayer film forming composition of the present invention can be applied to a substrate having a via hole used in a dual damascene process, and can be used as a filling material capable of filling the hole without gaps. It can also be used as a planarizing material for planarizing the surface of a semiconductor substrate having irregularities.

[0210] As described above, the composition for forming a resist underlayer film of the present invention can realize a resist underlayer film that has excellent embedding properties and flatness and exhibits hardness sufficient to withstand processing. Therefore, the composition for forming a resist underlayer film of the present invention is also very useful in a method for manufacturing a semiconductor device including pattern formation by the multilayer resist method as described above. EXAMPLES

[0211] The present invention will be described in more detail below with reference to Synthesis Examples, Comparative Synthesis Examples, Examples, and Comparative Examples, but the present invention is not limited thereto. Note that the molecular weight was determined as the weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) using tetrahydrofuran as an eluent.

[0212] [Synthesis example] In each of the following synthesis examples and comparative synthesis examples, any of the aromatic compounds Ar1 group (Ar1-1) to (Ar1-8), any of the aldehyde compounds (G1) to (G3) ((G1) is a 36 to 38% aqueous solution), and any of the etherification agents (R1-1) to (R1-8) shown below were used. Each raw material group is shown below.

[0213] [ka]

[0214] [ka]

[0215] [ka] (Ms is a methanesulfonyl group)

[0216] [Synthesis Example 1] Synthesis of compound (A-1) for forming resist underlayer film 5.0g of aromatic compound (Ar1-1), 6.9g of aldehyde compound (G2), 0.15g of paratoluenesulfonic acid monohydrate, and 25g of propylene glycol monomethyl ether (PGME) were mixed and stirred at 120°C for 20 hours. The mixture was returned to room temperature, 150g of hexane was added, and the upper layer was decanted. The residue was then dissolved in 150ml of methyl isobutyl ketone (MIBK) and washed twice with 100ml of water. The solvent was removed under reduced pressure, 200g of dimethylformamide (DMF) was added to the residue, and the solvent was further removed under reduced pressure. Then, 11.0g of potassium carbonate and an additional 20g of DMF were added to the residue and stirred at 90°C. 11.7g of etherification agent (R1-1) was added dropwise thereto, and after reacting for 5 hours, the temperature was lowered to 60°C. Furthermore, 3.8g of etherification agent (R1-2) was added to the mixture and reacted for 16 hours. The reaction product was returned to room temperature, washed with 150 ml of MIBK and 150 ml of water, and then washed with 100 ml of 3% aqueous nitric acid solution. The reaction product was then washed four times with 150 ml of water, and the solvent was removed under reduced pressure. Next, 300 g of PGMEA was added to the residue, and the solvent was removed again under reduced pressure to replace the PGMEA. This resulted in a PGMEA solution of the compound (A-1) for forming a resist underlayer film, which is a novolac resin.

[0217] (A-1): Mw=2198 [ka]

[0218] [Synthesis Example 2] Synthesis of compound (A-2) for forming resist underlayer film A PGMEA solution of a compound for forming a resist underlayer film (A-2), which is a novolak resin, was obtained in the same manner as in Synthesis Example 1, except that the 5.0 g of the aromatic compound (Ar1-1) used in Synthesis Example 1 was changed to 5.0 g of the aromatic compound (Ar1-2), the amount of the aldehyde compound (G2) was changed to 8.0 g, the amount of potassium carbonate added was changed to 12.6 g, and the etherification agents (R1-1) and (R1-2) were changed to 12.1 g of the etherification agent (R1-3) and 5.4 g of the etherification agent (R1-4), respectively.

[0219] (A-2): Mw=2439 [ka]

[0220] [Synthesis Example 3] Synthesis of compound (A-3) for forming resist underlayer film 5.0g of aromatic compound (Ar1-3), 5.5g of aldehyde compound (G3), 0.25g of paratoluenesulfonic acid monohydrate, and 30g of PGME were mixed and stirred at 120°C for 20 hours. The mixture was returned to room temperature and washed twice with 150ml of MIBK and 100ml of water. The solvent was removed under reduced pressure, 200g of dimethylformamide was added to the residue, and the solvent was further removed under reduced pressure. Then, 29.1g of potassium carbonate and an additional 60g of DMF were added to the residue and stirred at 90°C. 14.0g of etherification agent (R1-3) and 15.5g of etherification agent (R1-7) were dropped thereto and reacted for 20 hours. The reaction product was returned to room temperature, washed with 300ml of MIBK and 200ml of water, and washed with 150ml of 3% aqueous nitric acid solution. Furthermore, the reaction product was washed four times with 200ml of water, and the solvent was removed under reduced pressure. Next, 300 g of PGMEA was added to the residue, and the solvent was again removed under reduced pressure to replace it with PGMEA, thereby obtaining a PGMEA solution of a compound (A-3) for forming a resist underlayer film, which is a novolac resin.

[0221] (A-3): Mw=2251 [ka]

[0222] [Synthesis Example 4] Synthesis of compound (A-4) for forming resist underlayer film The aromatic compound and the aldehyde compound were subjected to a condensation reaction and solvent replacement in the same manner as in Synthesis Example 3. Then, 27.4 g of potassium carbonate and 60 g of DMF were added to the reaction product and stirred at 90°C. 14.0 g of etherification agent (R1-3) was added dropwise thereto, and after reacting for 5 hours, 21.0 g of etherification agent (R1-5) was added dropwise and reacted at 55°C for 20 hours. The reaction product was returned to room temperature, washed with 300 ml of MIBK and 200 ml of water, and washed with 150 ml of 3% aqueous nitric acid solution. The reaction product was further washed four times with 200 ml of water, and the solvent was removed under reduced pressure. Next, 300 g of PGMEA was added to the residue, and the solvent was removed again under reduced pressure, thereby replacing with PGMEA. As a result, a PGMEA solution of a compound for forming a resist underlayer film (A-4), which is a novolac resin, was obtained.

[0223] (A-4): Mw=2320 [ka]

[0224] [Synthesis Example 5] Synthesis of compound (A-5) for forming resist underlayer film 10.0g of aromatic compound (Ar1-4), 4.8g of aldehyde compound (G1), 0.3g of paratoluenesulfonic acid monohydrate, and 45g of PGME were mixed and stirred at 120°C for 20 hours. The mixture was returned to room temperature and washed twice with 150ml of MIBK and 100ml of water. The solvent was removed under reduced pressure, 200g of dimethylformamide was added to the residue, and the solvent was further removed under reduced pressure. Then, 17.3g of potassium carbonate and an additional 100g of DMF were added to the residue and stirred at 90°C. 18.3g of etherification agent (R1-3) was added dropwise thereto, and after reacting for 5 hours, 3.7g of etherification agent (R1-4) was added and reacted at 55°C for 16 hours. The reactant was returned to room temperature, washed with 300ml of MIBK and 200ml of water, and washed with 150ml of 3% aqueous nitric acid solution. Furthermore, the reaction product was washed four times with 200 ml of water, the solvent was removed under reduced pressure, 300 g of PGMEA was added, and the solvent was again removed under reduced pressure to replace with PGMEA, thereby obtaining a PGMEA solution of the compound (A-5) for forming a resist underlayer film, which is a novolac resin.

[0225] (A-5): Mw=5594 [ka]

[0226] [Synthesis Example 6] Synthesis of compound (A-6) for forming resist underlayer film 10.0 g of aromatic compound (Ar1-5), 7.8 g of aldehyde compound (G3), 7.0 g of 25% sodium hydroxide aqueous solution, and 50 g of PGME were mixed and stirred at 120°C for 20 hours. The mixture was returned to room temperature, 300 g of hexane was added, and the upper layer was decanted. Furthermore, 20 g of PGME was added to the residue, 200 g of hexane was added again, and the upper layer was decanted. The residue was dissolved in 150 ml of MIBK and washed twice with 100 ml of water. The solvent was removed under reduced pressure, 200 g of dimethylformamide was added to the residue, and the solvent was further removed under reduced pressure. Then, 34.5 g of potassium carbonate and an additional 50 g of DMF were added to the residue, and the mixture was stirred at 90°C. 33.2g of etherification agent (R1-3) was added dropwise thereto, and after reacting for 5 hours, 12.4g of etherification agent (R1-5) was added and reacted at 55°C for 16 hours. The reactant was returned to room temperature, washed with 300ml of MIBK and 200ml of water, and washed with 150ml of 3% aqueous nitric acid solution. The reactant was further washed four times with 200ml of water, the solvent was removed under reduced pressure, 300g of PGMEA was added, and the solvent was removed again under reduced pressure to replace PGMEA. This resulted in a PGMEA solution of the compound (A-6) for forming a resist underlayer film, which is a novolac resin.

[0227] (A-6): Mw=5501 [ka]

[0228] [Synthesis Example 7] Synthesis of compound (A-7) for forming resist underlayer film A PGMEA solution of a compound for forming a resist underlayer film (A-7), which is a novolak resin, was obtained in the same manner as in Synthesis Example 6, except that the 7.8 g of the aldehyde compound (G3) used in Synthesis Example 6 was changed to 11.0 g of the aldehyde compound (G2), the amount of potassium carbonate added was changed to 17.3 g, and the etherification agent was changed to 16.6 g of the etherification agent (R1-3) and 6.5 g of the etherification agent (R1-4).

[0229] (A-7): Mw=4425 [ka]

[0230] [Synthesis Example 8] Synthesis of compound (A-8) for forming resist underlayer film 5.0g of aromatic compound (Ar1-2), 5.0g of aromatic compound (Ar1-6), 4.5g of aldehyde compound (G1), 0.30g of paratoluenesulfonic acid monohydrate, and 40g of PGME were mixed and stirred at 120°C for 20 hours. The mixture was returned to room temperature, 200g of water was added, and the upper layer was decanted. The residue was then dissolved in 200ml of MIBK and washed twice with 150ml of water. The solvent was removed under reduced pressure, 200g of dimethylformamide was added to the residue, and the solvent was further removed under reduced pressure. Then, 22.0g of potassium carbonate and an additional 50g of DMF were added to the residue and stirred at 80°C. 20.7g of etherification agent (R1-3) was added dropwise thereto, and after reacting for 5 hours, 9.5g of etherification agent (R1-4) was added and reacted at 55°C for 16 hours. The reaction product was returned to room temperature, washed with 300 ml of MIBK and 200 ml of water, and washed with 150 ml of 3% aqueous nitric acid solution. The reaction product was further washed four times with 200 ml of water, the solvent was removed under reduced pressure, 300 g of PGMEA was added, and the solvent was again removed under reduced pressure to replace with PGMEA. This resulted in a PGMEA solution of the compound (A-8) for forming a resist underlayer film, which is a novolac resin.

[0231] (A-8): Mw=3755 [ka]

[0232] [Synthesis Example 9] Synthesis of compound (A-9) for forming resist underlayer film 10.0g of aromatic compound (Ar1-7), 1.6g of aldehyde compound (G1), 0.3g of paratoluenesulfonic acid monohydrate, and 30g of PGME were mixed and stirred at 120°C for 20 hours. After the mixture was returned to room temperature, 120g of water was added dropwise to it, and the upper layer was decanted. The residue was washed twice with 200ml of MIBK and 150ml of water. The solvent was removed under reduced pressure, 200g of dimethylformamide was added, and the solvent was further removed under reduced pressure. Then, 16.2g of potassium carbonate and an additional 80g of DMF were added to the residue, and the mixture was stirred at 90°C, and 15.6g of etherification agent (R1-3) and 2.9g of etherification agent (R1-7) were added dropwise thereto, and the reaction was carried out for 20 hours. The reaction product was returned to room temperature, washed with 300ml of MIBK and 200ml of water, and washed with 150ml of 3% aqueous nitric acid solution. Furthermore, the reaction product was washed four times with 200 ml of water, the solvent was removed under reduced pressure, 300 g of PGMEA was added, and the solvent was again removed under reduced pressure to replace with PGMEA, thereby obtaining a PGMEA solution of the compound (A-9) for forming a resist underlayer film, which is a novolac resin.

[0233] (A-9): Mw=4515 [ka]

[0234] [Synthesis Example 10] Synthesis of compound (A-10) for forming resist underlayer film The condensation reaction and solvent replacement of the aromatic compound and the aldehyde compound were carried out in the same manner as in Synthesis Example 9. Then, 16.2 g of potassium carbonate and 80 g of DMF were added to the reaction product and stirred at 90°C. 15.6 g of etherification agent (R1-3) was dropped therein, and after reacting for 5 hours, 5.8 g of etherification agent (R1-5) was further added and reacted at 55°C for 16 hours. The reaction product was returned to room temperature, washed with 300 ml of MIBK and 200 ml of water, and washed with 150 ml of 3% aqueous nitric acid solution. The reaction product was further washed four times with 200 ml of water, and the solvent was removed under reduced pressure. Next, 300 g of PGMEA was added to the residue, and the solvent was removed again under reduced pressure, thereby replacing with PGMEA. As a result, a PGMEA solution of a compound for forming a resist underlayer film (A-10), which is a novolac resin, was obtained.

[0235] (A-10): Mw=4678 [ka]

[0236] [Synthesis Example 11] Synthesis of compound (A-11) for forming resist underlayer film A PGMEA solution of a compound (A-11) for forming a resist underlayer film, which is a novolak resin, was obtained in the same manner as in Synthesis Example 10, except that the etherification agent (R1-3) used in Synthesis Example 10 was changed to 17.1 g of the etherification agent (R1-7).

[0237] (A-11): Mw=4705 [ka]

[0238] [Synthesis Example 12] Synthesis of compound (A-12) for forming resist underlayer film A PGMEA solution of a compound for forming a resist underlayer film (A-12), which is a novolak resin, was obtained in the same manner as in Synthesis Example 9, except that the etherification agent (R1-3) used in Synthesis Example 10 was changed to 19.4 g of the etherification agent (R1-8).

[0239] (A-12): Mw=4611 [ka]

[0240] [Synthesis Example 13] Synthesis of compound (A-13) for forming resist underlayer film A PGMEA solution of a compound for forming a resist underlayer film (A-13), which is a novolak resin, was obtained in the same manner as in Synthesis Example 10, except that the amount of the aldehyde compound (G1) used in Synthesis Example 10 was changed to 2.0 g.

[0241] (A-13): Mw=7600 [ka]

[0242] [Synthesis Example 14] Synthesis of compound (A-14) for forming resist underlayer film 10.0g of aromatic compound (Ar1-8), 1.7g of aldehyde compound (G1), 0.25g of paratoluenesulfonic acid monohydrate, and 30g of PGME were mixed and stirred at 120°C for 20 hours. The mixture was returned to room temperature, 200g of hexane was added, and the upper layer was decanted. The residue was dissolved in 150ml of MIBK and washed twice with 100ml of water. The solvent was removed under reduced pressure, 200g of dimethylformamide was added to the residue, and the solvent was further removed under reduced pressure. Then, 8.1g of potassium carbonate and an additional 50g of DMF were added to the residue and stirred at 90°C, and 7.8g of etherification agent (R1-3) was dropped therein, and after reacting for 5 hours, 2.8g of etherification agent (R1-6) was further added and reacted at 55°C for 16 hours. The reaction product was returned to room temperature, washed with 300 ml of MIBK and 200 ml of water, and washed with 150 ml of 3% aqueous nitric acid solution. It was further washed four times with 200 ml of water, the solvent was removed under reduced pressure, 300 g of PGMEA was added, and the solvent was removed again under reduced pressure to replace with PGMEA. This resulted in a PGMEA solution of the compound for forming resist underlayer film (A-14), which is a novolac resin.

[0243] (A-14): Mw=5850 [ka]

[0244] [Synthesis Example 15] Synthesis of compound (A-15) for forming resist underlayer film 5.0g of aromatic compound (Ar1-5), 2.7g of aldehyde compound (G3), 0.25g of paratoluenesulfonic acid monohydrate, and 30g of PGME were mixed, and the mixture was stirred at 120°C for 8 hours. Then, 1.6g of aldehyde compound (G1) was added to the mixture, and the reaction was continued for another 12 hours. The reactant was dissolved in 150ml of MIBK and washed twice with 100ml of water. The solvent was removed under reduced pressure, 200g of dimethylformamide was added to the residue, and the solvent was removed under reduced pressure. Then, 21.9g of potassium carbonate and an additional 50g of DMF were added to the residue, and the mixture was stirred at 90°C, and 15.6g of etherification agent (R1-3) was added dropwise thereto, and the mixture was reacted for 5 hours, after which 11.2g of etherification agent (R1-5) was added and the mixture was reacted at 55°C for 16 hours. The reaction product was returned to room temperature, washed with 300 ml of MIBK and 200 ml of water, and washed with 150 ml of 3% aqueous nitric acid solution. The reaction product was further washed four times with 200 ml of water, the solvent was removed under reduced pressure, 300 g of PGMEA was added, and the solvent was again removed under reduced pressure to replace with PGMEA. This resulted in a PGMEA solution of the compound for forming resist underlayer film (A-15), which is a novolac resin.

[0245] (A-15): Mw = 3670 [ka]

[0246] [Comparative Synthesis Example 1] Synthesis of compound (R-1) for forming resist underlayer film A PGMEA solution of a compound for forming a resist underlayer film (R-1), which is a novolak resin, was obtained in the same manner as in Synthesis Example 5, except that the etherification agent in Synthesis Example 5 was changed to only 20.4 g of (R1-4) and the reaction temperature was fixed at 55°C.

[0247] (R-1): Mw = 5324 [ka]

[0248] [Comparative Synthesis Example 2] Synthesis of compound (R-2) for forming resist underlayer film 10.0g of 1,5-dihydroxynaphthalene, 10.13g of 4-tert-butylbenzaldehyde, 50g of PGMEA, and 1.2g of methanesulfonic acid were mixed and reacted at 150°C for 2 hours. After the reaction was completed, the reaction solution was dropped into a mixed solution of methanol / water, reprecipitated, and the supernatant was decanted. 100g of PGMEA was added to the residue, and the solvent was replaced by drying under reduced pressure. This resulted in a PGMEA solution of a compound for forming a resist underlayer film (R-2), which is a novolac resin.

[0249] (R-2): Mw=4110 [ka]

[0250] [Comparative Synthesis Example 3] Synthesis of compound (R-3) for forming resist underlayer film 10.0g of phenylnaphthylamine, 8.2g of 9-fluorenone, 1.3g of methanesulfonic acid, and 20g of propylene glycol monomethyl ether acetate were mixed. The mixture was then heated to reflux under nitrogen and reacted for 14 hours. After the reaction was stopped, the reactant was reprecipitated with methanol, and the upper layer was decanted. 100g of PGMEA was added to the residue, and the mixture was dried under reduced pressure. This resulted in a PGMEA solution of a compound for forming a resist underlayer film (R-3), which is a novolac resin.

[0251] (R-3): Mw=1900 [ka]

[0252] [Composition for forming resist underlayer film UDL-1] The resist underlayer film-forming compound (A-1) was dissolved in propylene glycol monomethyl ether acetate (PGMEA) containing 0.5 mass % of a surfactant FC-4430 (manufactured by Sumitomo 3M Limited) in the ratio shown in Table 1, and the solution was filtered through a 0.02 μm membrane filter to prepare a resist underlayer film-forming composition (UDL-1).

[0253] [Preparation of compositions for forming resist underlayer films (UDL-2 to 26) and compositions for forming resist underlayer films for comparative examples (UDL-1 to 3 for comparative examples)] Each chemical solution was prepared in the same manner as in the composition for forming resist underlayer film (UDL-1), except that the type and content of each component were as shown in Table 1. In Table 1, "-" indicates that the corresponding component was not used. The crosslinking agent used was the one shown in the following formula (D-1), the thermally decomposable resin used was the one shown in the following formula (E-1), the high boiling point solvent used was 1,6-diacetoxyhexane (B1-1): boiling point 260°C, and the thermal acid generator used was the one shown in the following formula (TAG-1).

[0254] [Crosslinking agent] The crosslinking agent (D-1) used in the composition for forming the resist underlayer film is shown below.

[0255] [ka]

[0256] [Example of synthesis of thermally decomposable resin] Synthesis of thermally decomposable resin (E-1) To a mixture of 3.8 g of a cation exchange resin (Amberlyst (registered trademark) 15) and 100 g of ethyl acetate, 100 g of diethylene glycol monovinyl ether was added at room temperature and further stirred for 3 hours. 0.8 g of triethylamine was added to the resulting mixture to stop the reaction, and the cation exchange resin was removed by filtration. The filtrate was concentrated under reduced pressure to obtain 100 g of a pyrolyzable resin polymer (E-1) as a highly viscous liquid.

[0257] The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, giving the following results: Mw=5,200, Mw / Mn=2.64.

[0258] [ka]

[0259] [Thermal acid generator] The crosslinking agent (TAG-1) used in the composition for forming the resist underlayer film is shown below.

[0260] [ka]

[0261] [Table 1]

[0262] [Solvent resistance test] Each of the resist underlayer film forming compositions (UDL-1 to 26, Comparative Examples UDL-1 to 3) prepared above was applied onto a silicon substrate to obtain a coating film. The obtained coating film was baked at 180°C for 60 seconds, and then further baked at 350°C for 60 seconds. As a result, each resist underlayer film with a thickness of about 200 nm was formed.

[0263] The thickness (FT-1 [nm]) of the resist underlayer film formed was measured. Furthermore, OK73 thinner (propylene glycol monomethyl ether / propylene glycol monomethyl ether acetate = 7 / 3) was dispensed on the resist underlayer film, then left for 30 seconds, then the resist underlayer film was spin-dried, and then the resist underlayer film was baked at 100 ° C for 60 seconds to evaporate the OK73 thinner (reworked). The thickness (FT-2 [nm]) of the resist underlayer film reworked in this way was measured.

[0264] The difference in film thickness before and after the treatment (film remaining rate: (FT-2 / FT-1) x 100) was determined. The results are shown in Table 2 below.

[0265] [Contact angle measurement / Hardness measurement] Each of the resist underlayer film forming compositions (UDL-1 to 26, Comparative Examples UDL-1 to 3) prepared above was applied onto a silicon substrate to obtain a coating film. Next, the coating film was baked at 180°C for 60 seconds, and then further baked at 350°C for 60 seconds. As a result, each resist underlayer film with a thickness of about 200 nm was formed.

[0266] The contact angle of these resist underlayer films with pure water was measured. In addition, a nanoindentation test was performed using a Nanoindenter SA2 type device manufactured by Toyo Corporation to measure the hardness of the resist underlayer films. The results are shown in Table 2.

[0267] [Table 2]

[0268] As shown in Table 2, in Examples 1-1 to 1-15 of the resist underlayer film forming composition of the present invention, the residual film ratio ((FT-2 / FT-1)×100) before and after rework all exceeded 100.5%, suggesting that the film after baking was a porous film with many pores through which OK73 thinner could penetrate, and that the film density was low. In addition, in Examples 1-9 to 1-14, which have a spiro ring structure in the mother nucleus, the residual film ratio exceeded 102%, at 102%<((FT-2 / FT-1)×100), suggesting that the porosity was further increased by the two effects of the cyclic alkyl structure of the mother nucleus and the cyclic alkyl ether of the substituent. In addition, in each of Examples 1-16 to 1-19 in which a crosslinking agent was added, the residual film ratio ((FT-2 / FT-1) x 100) before and after rework was slightly suppressed compared to the corresponding Examples 1-4, 1-5, 1-7, and 1-10 in which no crosslinking agent was added, while the hardness was increased, resulting in improved processing resistance. In addition, in each of Examples 1-20 to 1-23 in which a thermally decomposable resin was added, the residual film ratio ((FT-2 / FT-1) x 100) before and after rework was increased compared to the corresponding Examples 1-4, 1-5, 1-7, and 1-10 in which no crosslinking agent was added. This shows that the porosity can be adjusted by adding a crosslinking agent and a thermally decomposable resin.

[0269] In Comparative Example 1-1 in which R1 was a single group within the same resin, and Comparative Example 2 in which there was no ether substitution, the improvement in the residual film rate was low and the porosity was insufficient.

[0270] In Comparative Example 1-3, no improvement in the residual film rate was confirmed, and it was found that the porosity was inferior.

[0271] In addition, the contact angle was high at 60° or more in Examples 1-1, 1-2, and 1-7 where fluorine was introduced, and was around 50° in those where fluorine was not introduced, and it was confirmed that it may be possible to use each depending on the hydrophilicity or hydrophobicity of the gas used. In addition, the hardness measured as an index of processing resistance was generally over 0.6 GPa, with some being 0.8 GPa, so it was confirmed that there was sufficient processing resistance.

[0272] [Evaluation of embedding characteristics] The resist underlayer film forming compositions (UDL-1 to 26, Comparative Examples UDL-2 to 3) prepared above were each applied onto a SiO2 wafer substrate having a dense hole pattern (hole diameter 0.16 μm, hole depth 0.50 μm, distance between the centers of two adjacent holes 0.32 μm), and the applied film was baked at 180° C. for 60 seconds, and then further baked at 350° C. for 60 seconds. As a result, each resist underlayer film with a thickness of 200 nm was formed on the substrate having the dense hole pattern.

[0273] The cross-sectional shape of each of the obtained wafer substrates was observed using an electron microscope (S-4700) manufactured by Hitachi, Ltd., to confirm whether the holes were filled with an organic film without any voids (air gaps). The results are shown in Table 3 below. When a composition for forming a resist underlayer film with poor filling properties was used, voids were generated inside the holes. When a composition for forming a resist underlayer film with good filling properties was used, the organic film was filled without any voids in this evaluation. The evaluation was as follows: A: Filling possible without voids, B: Microvoids present, C: Voids present or filling not possible.

[0274] [Table 3]

[0275] As shown in Table 3, in Examples 2-1 to 2-26 in which the resist underlayer film forming compositions of the present invention (UDL-1 to 26) were used, except for Example 2-13, it was possible to fill a dense line and space pattern without generating voids, and it was confirmed that the compositions had good filling properties. It is presumed that the polymer used in Example 2-13, in which voids were observed at the bottom, had a larger molecular weight than the others, and as a result, it was not possible to fill all the way to the bottom without any gaps, which resulted in the appearance of voids after baking.

[0276] In Comparative Example 2-1, which used Comparative Example UDL-2, the result was that the resin was not embedded. This is thought to be because the compound R-2 of Comparative Example UDL-2 does not have an ether substituent and remains a rigid resin structure, so the resin has low fluidity and cannot be embedded in the fine pattern.

[0277] In addition, in Comparative Example 2-2, which used Comparative Example UDL-3, a larger void was confirmed in the bottom than in Example 2-13. This is thought to be because the resin in Comparative Example UDL-3 does not have crosslinking properties itself, and a large amount of crosslinking agent and thermal acid generator was added, which resulted in decomposition of the resin and additives and a large amount of sublimation.

[0278] [Flattening characteristics evaluation] Each of the resist underlayer film forming compositions prepared above was applied onto a SiO2 wafer substrate having a giant isolated trench pattern (trench width 10 μm, trench depth 0.1 μm), and the resulting coating film was baked at 180 ° C for 60 seconds, and then further baked at 350 ° C for 60 seconds. In this way, each resist underlayer film was formed on a substrate having a giant isolated trench pattern. The step between the trench portion and the non-trench portion of the resist underlayer film was observed using an atomic force microscope (AFM) NX10 manufactured by Park Systems. The results are shown in Table 4. In this evaluation, the smaller the step, the better the planarization characteristics. In this evaluation, a trench pattern with a depth of 0.10 μm was planarized using an organic film forming composition with a normal film thickness of about 0.2 μm, and the evaluation conditions were strict to evaluate the superiority or inferiority of the planarization characteristics.

[0279] [Table 4]

[0280] As shown in Table 4, in Examples 3-1 to 3-4 using resist underlayer film forming compositions UDL-4, 5, 7 and 10, which are examples of the present invention, the step between the patterned portion and the non-patterned portion of the film was small compared to Comparative Example 3-2 having no ether structure and Comparative Example 3-3 having a significantly different resin structure, and it was confirmed that the planarization characteristics were excellent. In addition, it was confirmed that Examples 3-1 to 3-4 have a small step and excellent planarization characteristics compared to Comparative Example 3-1 in which R1 in the above general formula (1) is a single ether structure in the same resin, and all of them have the same ether structure, and it can be seen that the thermal fluidity is improved by including multiple types of ether structures as in the above general formula (1), and excellent planarization characteristics are expressed. In particular, Example 3-4 using resist underlayer film forming composition UDL-10 containing resist underlayer film forming compound (A-10) synthesized by mixing other types of carboxylic acids with long alkyl chains showed better planarization characteristics.

[0281] In addition, when comparing Examples 3-5 to 12 in which a crosslinking agent (D-1) or a thermally decomposable resin (E-1) was added with Examples 3-1 to 3-4 in which no crosslinking agent was added, there was no significant change in flatness, and it is believed that the addition of a crosslinking agent or a thermally decomposable resin that can adjust the porosity of the film does not have a significant effect on flatness. In addition, Examples 3-13 to 3-14 in which a high boiling point solvent (B2-1) was added showed improved flatness compared to Examples 3-1 and 3-4 in which no high boiling point solvent was added. This is believed to be due to the improvement in thermal fluidity caused by the high boiling point solvent.

[0282] From the above, the composition for forming a resist underlayer film of the present invention exhibits high filling and planarization properties that can be used as an underlayer film, has high hardness and excellent processing resistance, and can form a porous and low-density film, so that it can provide a resist underlayer film that is also excellent in gas permeability. Such a resist underlayer film is particularly useful for nanoimprinting and is also suitable for use in a multilayer resist process.

[0283] The present specification includes the following aspects. [1] A composition for forming a resist underlayer film, comprising: (A) a novolak resin having a repeating unit structure represented by the following general formula (I) and / or (II); and (B) an organic solvent: [ka] (In the above general formulas (I) and (II), Ar1 and Ar2 are each independently a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted heteroaryl group having 6 to 30 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms condensed or connected to an aliphatic ring or an ether ring, or a plurality of substituted or unsubstituted aryl groups having 6 to 30 carbon atoms connected to each other via a linear, branched or cyclic hydrocarbon group, an ether group or a carbonyl group; Ar1 ​​may be one type or a combination of multiple types in the same resin, and Ar2 may be one type or a combination of multiple types in the same resin. R1 is and a combination of at least two or more of them, which are a hydrogen atom, a substituted or unsubstituted linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted linear, branched or cyclic alkenyl group having 2 to 20 carbon atoms, or a substituted or unsubstituted linear, branched or cyclic alkynyl group having 2 to 20 carbon atoms. R2 is any one of a substituted or unsubstituted linear, branched or cyclic saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms, an amino group, a thiol group, and a halogen atom. n1 is an integer of 1 or more. 、 n2, n3, and n4 are integers equal to or greater than 0. [2] In the above formulas (I) and (II), at least one of R1 is a structure R selected from the group consisting of groups represented by the following formula (III-1): 1-1 The composition for forming a resist underlayer film according to [1], [ka] (In formula (III-1), * represents a bond to an oxygen atom.) [3] In the above formulas (I) and (II), R1 is a structure R selected from the group consisting of groups shown in the following (III-1): 1-1 and a structure R selected from the group consisting of groups represented by the following formula (III-2): 1-2 It is a combination of structure R 1-1 The ratio of a to R 1-2 The composition for forming a resist underlayer film according to [1], characterized in that, when the ratio of a is b, the ratios a and b satisfy the relationships of 1≦a≦99, 1≦b≦99, and a+b=100. [ka] (In formulas (III-1) and (III-2), * represents a bond to an oxygen atom.) [4] The composition for forming a resist underlayer film according to any one of [1] to [3], wherein, in the above general formula (II), Ar2 is a benzene ring. [5] The composition for forming a resist underlayer film according to any one of [1] to [4], wherein in the above general formulas (I) and (II), Ar1 is selected from the group consisting of structures represented by the following formula (Ar-1): [ka] [6] The composition for forming a resist underlayer film according to any one of [1] to [5], wherein in the above general formula (II), n3+n4 is an integer of 2 or more. [7] The composition for forming a resist underlayer film according to any one of [1] to [6], wherein the (A) novolak resin has a weight average molecular weight Mw of 2,000 to 8,000 in terms of polystyrene, as determined by a gel permeation chromatography method. [8] The composition for forming a resist underlayer film according to any one of [1] to [7], wherein FT-2 is a thickness of the coating film obtained by applying the composition for forming a resist underlayer film to a substrate to obtain a coating film, baking the coating film at 180°C for 60 seconds, and then additionally baking the coating film at 350°C for 60 seconds, and dispensing OK73 thinner obtained by mixing propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate in a ratio of 7:3 onto the coating film after the additional baking, leaving the coating film for 30 seconds, spin-drying the coating film, and baking the coating film at 100°C for 60 seconds to evaporate the OK73 thinner, and the thickness of the coating film is 100.5<{(FT-2) / (FT-1)}×100. [9] The composition for forming a resist underlayer film according to any one of [1] to [8], further comprising (C) a surfactant.

[10] (D) A resist underlayer film forming composition further comprising a crosslinking agent, the resist underlayer film forming composition is applied to a substrate to obtain a coating film, the coating film is baked at 180° C. for 60 seconds, and then additionally baked at 350° C. for 60 seconds. The thickness of the coating film after the additional baking is defined as FT-1. After the additional baking, OK73 thinner obtained by mixing propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate in a ratio of 7:3 is dispensed onto the coating film, and the coating film is left for 30 seconds. The coating film is then spin-dried, and then baked at 100° C. for 60 seconds to evaporate the OK73 thinner. The thickness of the coating film after the additional baking is defined as FT-2. The composition for forming a resist underlayer film according to any one of [1] to [7], wherein

[11] (E) The composition for forming a resist underlayer film according to any one of [1] to [7], further comprising a thermally decomposable resin, wherein FT-1 is a thickness of the coating film obtained by applying the composition for forming a resist underlayer film to a substrate to obtain a coating film, baking the coating film at 180°C for 60 seconds and then additionally baking at 350°C for 60 seconds, and FT-2 is a thickness of the coating film obtained by dispensing OK73 thinner obtained by mixing propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate in a ratio of 7:3 onto the coating film after the additional baking, leaving the coating film for 30 seconds, spin-drying the coating film, and baking the coating film at 100°C for 60 seconds to evaporate the OK73 thinner, such that FT-2 satisfies 101<{(FT-2) / (FT-1)}×100.

[12] The composition for forming a resist underlayer film according to any one of [1] to [7], further comprising both (D) a crosslinking agent and (E) a thermally decomposable resin, wherein the composition for forming a resist underlayer film is applied to a substrate to obtain a coating film, the coating film is baked at 180°C for 60 seconds, and then additionally baked at 350°C for 60 seconds, and the thickness of the coating film after the additional baking is defined as FT-1, and OK73 thinner obtained by mixing propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate in a ratio of 7:3 is dispensed onto the coating film after the additional baking, and then the coating film is left to stand for 30 seconds, and then the coating film is spin-dried, and then the coating film is baked at 100°C for 60 seconds to evaporate the OK73 thinner, where FT-2 satisfies 100<{(FT-2) / (FT-1)}×100.

[13] (F) The composition for forming a resist underlayer film according to any one of [1] to

[12] , further comprising an acid generator.

[14] The composition for forming a resist underlayer film according to any one of [1] to

[13] , wherein the composition for forming a resist underlayer film is for nanoimprinting.

[15] A resist underlayer film, which is a cured product of a coating film made of the composition for forming a resist underlayer film according to any one of [1] to

[13] .

[16] A method for producing a resist underlayer film, comprising: applying the composition for forming a resist underlayer film according to any one of [1] to

[13] onto a semiconductor substrate to obtain a coating film; and baking the coating film to obtain a resist underlayer film.

[17] A pattern formation method, comprising the steps of: forming a resist underlayer film on a semiconductor substrate from a resist underlayer film-forming composition according to any one of [1] to

[13] ; forming a curable composition film on the resist underlayer film; contacting the curable composition film with a mold; irradiating the curable composition film with light or an electron beam to form a cured film; and separating the cured film from the mold.

[18] The pattern formation method according to

[17] , wherein the step of forming a curable composition film on the resist underlayer film comprises forming an adhesion layer and / or a silicone layer containing 99 mass % or less of Si on the resist underlayer film by coating or vapor deposition, and then forming a curable composition film thereon.

[19] A method for manufacturing a semiconductor device, comprising the steps of: forming a resist underlayer film on a semiconductor substrate from the composition for forming a resist underlayer film according to any one of [1] to

[13] ; forming a resist film on the resist underlayer film; irradiating the resist film with light or an electron beam and then developing it to form a resist pattern; etching the resist underlayer film using the formed resist pattern as a mask to obtain a patterned underlayer film; and processing the semiconductor substrate using the patterned underlayer film as a mask.

[20] A method for manufacturing a semiconductor device, comprising the steps of: forming a resist underlayer film on a semiconductor substrate from the composition for forming a resist underlayer film according to any one of [1] to

[13] ; forming a hard mask on the resist underlayer film; further forming a resist film on the hard mask; irradiating the resist film with light or an electron beam, followed by development, to form a resist pattern; etching the hard mask using the formed resist pattern as a mask to obtain a patterned hard mask; etching the underlayer film using the patterned hard mask as a mask to obtain a patterned resist underlayer film; and processing the semiconductor substrate using the patterned resist underlayer film as a mask.

[0284] The present invention is not limited to the above-described embodiment. The above-described embodiment is merely an example, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits similar effects is included in the technical scope of the present invention.

Claims

1. (A) a novolak resin having a repeating unit structure represented by the following general formula (I) and / or (II), (B) an organic solvent; A composition for forming a resist underlayer film, comprising: 【Chemistry 1】 (In the above general formulas (I) and (II), Ar １ and Ar ２ are each independently a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted heteroaryl group having 6 to 30 carbon atoms, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms condensed with or connected to an aliphatic ring or an ether ring, or a plurality of substituted or unsubstituted aryl groups having 6 to 30 carbon atoms connected to each other via a linear, branched or cyclic hydrocarbon group, an ether group or a carbonyl group; １ may be one type or a combination of multiple types in the same resin, Ar ２ may be one type or a combination of multiple types in the same resin. １ is a combination of at least two or more in the same resin, and is a hydrogen atom, a substituted or unsubstituted linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted linear, branched or cyclic alkenyl group having 2 to 20 carbon atoms, or a substituted or unsubstituted linear, branched or cyclic alkynyl group having 2 to 20 carbon atoms. ２ is any one of a substituted or unsubstituted linear, branched or cyclic saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms, an amino group, a thiol group, and a halogen atom. １ is an integer equal to or greater than 1 、 n ２ , n ３ and n ４ is an integer equal to or greater than 0.)

2. In the above formulas (I) and (II), R １ At least one of the structures R is selected from the group consisting of groups represented by the following formula (III-1): １－１ 2. The composition for forming a resist underlayer film according to claim 1, 【Chemistry 2】 (In formula (III-1), * represents a bond to an oxygen atom.)

3. In the above formulas (I) and (II), R １ is a structure R selected from the group consisting of groups shown in (III-1) below. １－１ and a structure R selected from the group consisting of groups represented by the following formula (III-2): １－２ and the structure R １－１ The ratio of the structure R １－２ 2. The composition for forming a resist underlayer film according to claim 1, wherein the ratios a and b satisfy the relationships 1≦a≦99, 1≦b≦99, and a+b=100, where b is the ratio of a. 【Chemistry 3】 (In formulas (III-1) and (III-2), * represents a bond to an oxygen atom.)

4. In the above general formula (II), Ar ２ The composition for forming a resist underlayer film according to claim 1 , wherein is a benzene ring.

5. In the above general formulas (I) and (II), Ar １ is selected from the group consisting of structures represented by the following formula (Ar-1): 【Chemistry 4】

6. In the above general formula (II), n ３ +n ４ 2. The composition for forming a resist underlayer film according to claim 1, wherein is an integer of 2 or more.

7. 2. The composition for forming a resist underlayer film according to claim 1, wherein the novolak resin (A) has a weight average molecular weight Mw of 2,000 to 8,000 in terms of polystyrene as determined by gel permeation chromatography.

8. The composition for forming a resist underlayer film is applied to a substrate to obtain a coating film, the coating film is baked at 180° C. for 60 seconds, and then additionally baked at 350° C. for 60 seconds. The thickness of the coating film after the baking is designated as FT-1, After the additional baking, OK73 thinner obtained by mixing propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate in a ratio of 7:3 was dispensed onto the coating film, which was then left for 30 seconds, spin-dried, and baked at 100° C. for 60 seconds to evaporate the OK73 thinner. When the thickness of the coating film was FT-2, 100.5<{(FT-2) / (FT-1)}×100 2. The composition for forming a resist underlayer film according to claim 1,

9. The composition for forming a resist underlayer film according to claim 1 , further comprising (C) a surfactant.

10. (D) further comprising a crosslinking agent; The composition for forming a resist underlayer film is applied to a substrate to obtain a coating film, the coating film is baked at 180° C. for 60 seconds, and then additionally baked at 350° C. for 60 seconds. The thickness of the coating film after the baking is designated as FT-1, After the additional baking, OK73 thinner obtained by mixing propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate in a ratio of 7:3 was dispensed onto the coating film, which was then left for 30 seconds, spin-dried, and baked at 100° C. for 60 seconds to evaporate the OK73 thinner. When the thickness of the coating film was FT-2, 100<{(FT-2) / (FT-1)}×100<101 2. The composition for forming a resist underlayer film according to claim 1,

11. (E) further comprising a thermally decomposable resin; The composition for forming a resist underlayer film is applied to a substrate to obtain a coating film, the coating film is baked at 180° C. for 60 seconds, and then additionally baked at 350° C. for 60 seconds. The thickness of the coating film after the baking is designated as FT-1, After the additional baking, OK73 thinner obtained by mixing propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate in a ratio of 7:3 was dispensed onto the coating film, which was then left for 30 seconds, spin-dried, and baked at 100° C. for 60 seconds to evaporate the OK73 thinner. When the thickness of the coating film was FT-2, 101<{(FT-2) / (FT-1)}×100 2. The composition for forming a resist underlayer film according to claim 1,

12. Further comprising both (D) a crosslinking agent and (E) a thermally decomposable resin; The composition for forming a resist underlayer film is applied to a substrate to obtain a coating film, the coating film is baked at 180° C. for 60 seconds, and then additionally baked at 350° C. for 60 seconds. The thickness of the coating film after the baking is designated as FT-1, After the additional baking, OK73 thinner obtained by mixing propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate in a ratio of 7:3 was dispensed onto the coating film, which was then left for 30 seconds, spin-dried, and baked at 100° C. for 60 seconds to evaporate the OK73 thinner. When the thickness of the coating film was FT-2, 100<{(FT-2) / (FT-1)}×100 2. The composition for forming a resist underlayer film according to claim 1,

13. 2. The composition for forming a resist underlayer film according to claim 1, further comprising (F) an acid generator.

14. The composition for forming a resist underlayer film according to any one of claims 1 to 13, wherein the composition for forming a resist underlayer film is for nanoimprinting.

15. A resist underlayer film, which is a cured product of a coating film comprising the composition for forming a resist underlayer film according to any one of claims 1 to 13.

16. Coating a composition for forming a resist underlayer film according to any one of claims 1 to 13 on a semiconductor substrate to obtain a coating film; baking the coating film to obtain a resist underlayer film. A method for producing a resist underlayer film, comprising:

17. A pattern formation method comprising the steps of: forming a resist underlayer film on a semiconductor substrate from the composition for forming a resist underlayer film according to any one of claims 1 to 13; forming a curable composition film on the resist underlayer film; contacting the curable composition film with a mold; a step of irradiating the curable composition film with light or an electron beam to form a cured film; separating the cured film from the mold; A pattern forming method comprising the steps of:

18. The pattern forming method according to claim 17, wherein the step of forming a curable composition film on the resist underlayer film comprises forming an adhesion layer and / or a silicone layer containing 99% by mass or less of Si on the resist underlayer film by coating or vapor deposition, and forming a curable composition film thereon.

19. A method for manufacturing a semiconductor device, comprising: forming a resist underlayer film on a semiconductor substrate from the composition for forming a resist underlayer film according to any one of claims 1 to 13; forming a resist film on the resist underlayer film; a step of irradiating the resist film with light or an electron beam, and then developing the resist film to form a resist pattern; a step of etching the resist underlayer film using the formed resist pattern as a mask to obtain a patterned underlayer film; processing the semiconductor substrate using the patterned underlayer film as a mask; 2. A method for manufacturing a semiconductor device comprising the steps of:

20. A method for manufacturing a semiconductor device, comprising: forming a resist underlayer film on a semiconductor substrate from the composition for forming a resist underlayer film according to any one of claims 1 to 13; forming a hard mask on the resist underlayer film; further forming a resist film on the hard mask; a step of irradiating the resist film with light or an electron beam, and then developing the resist film to form a resist pattern; Etching the hard mask using the formed resist pattern as a mask to obtain a patterned hard mask; Etching the underlayer film using the patterned hard mask as a mask to obtain a patterned resist underlayer film; processing the semiconductor substrate using the patterned resist underlayer film as a mask; 2. A method for manufacturing a semiconductor device comprising the steps of:

Images