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

Abstract

The invention relates to a resist underlayer film forming composition, a pattern forming method, and a resist underlayer film forming method. The present invention addresses the problem of providing a composition for forming a resist underlayer film, said composition being capable of forming a resist underlayer film exhibiting excellent dry etching resistance compared to known organic underlayer film materials. A composition for forming a resist underlayer film, characterized by containing (A) a polymer having a structure represented by general formula (1) as a repeating unit and (B) an organic solvent, the molecular weight of the (A) polymer being 300-3,000, and the (A) polymer not containing a repeating unit containing a hydroxyl group as a substituent and not containing a repeating unit containing a heteroaromatic ring. In formula (1) in # imgabs0 #, Ar is an unsubstituted divalent aromatic group having 6 to 30 carbon atoms.

Description

Technical Field

[0001] The present invention relates to a resist underlayer film forming composition, a pattern forming method, and a resist underlayer film forming method. More specifically, the present invention relates to a resist underlayer film forming composition that can be used for fine patterning using a multilayer resist method in a semiconductor device manufacturing step, a pattern forming method using the material, and a resist underlayer film forming method. Background Art

[0002] With the high integration and high speed of LSI, the miniaturization of pattern size is progressing rapidly. With this miniaturization, photolithography technology has achieved the formation of fine patterns by shortening the wavelength of the light source and appropriately selecting the corresponding resist composition. The core of this is the positive photoresist composition used in a single layer. This single-layer positive photoresist composition has a skeleton with etching resistance to dry etching using chlorine-based or fluorine-based gas plasma in the resist resin and a switching mechanism that dissolves the exposed part, thereby dissolving the exposed part to form a pattern, and using the remaining resist pattern as an etching mask to dry etch the substrate to be processed.

[0003] However, if the thickness of the photoresist film used is directly miniaturized, that is, if the pattern width is further reduced, the resolution performance of the photoresist film will be reduced, and if the photoresist film is to be patterned using a developer, the so-called aspect ratio will become too large, resulting in a problem of pattern collapse. Therefore, as the pattern becomes miniaturized, the photoresist film will become thinner and thinner.

[0004] On the other hand, the processing of the processed substrate usually uses a method of processing the substrate by dry etching using a patterned photoresist film as an etching mask, but in reality there is no dry etching method that can obtain complete etching selectivity between the photoresist film and the processed substrate. Therefore, in the substrate processing, there will be a problem that even the photoresist film is damaged and collapsed, and the resist pattern cannot be correctly transferred to the processed substrate. With the miniaturization of the pattern, higher dry etching resistance is required for the resist composition. However, on the other hand, in order to improve the resolution, the resin used in the photoresist composition is increasingly required to have a small light absorption at the exposure wavelength. Therefore, as the exposure light progresses to the shorter wavelength of i-rays, KrF, and ArF, the resin also changes to novolac resin, polyhydroxystyrene, and resin with an aliphatic polycyclic skeleton. However, in reality, the etching speed of the dry etching conditions during substrate processing becomes faster, and the recent photoresist composition with high resolution tends to weaken the etching resistance instead.

[0005] Therefore, the substrate to be processed must be dry-etched with a thinner photoresist film with weaker etching resistance, and ensuring the materials and processing in this processing step becomes a top priority.

[0006] One method for solving such a problem is a multilayer resist method. This method is to insert a resist intermediate film having a different etching selectivity from the photoresist film (i.e., the resist upper film) between the resist upper film and the substrate to be processed, and after obtaining a pattern on the resist upper film, use the resist upper film pattern as a dry etching mask to transfer the pattern to the resist intermediate film by dry etching, and then use the resist intermediate film as a dry etching mask to transfer the pattern to the substrate to be processed by dry etching.

[0007] One of the multilayer resist methods is a three-layer resist method that can be implemented using a general resist composition used in the single-layer resist method. In this three-layer resist method, for example, an organic film obtained from a novolac resin or the like is formed on a substrate to be processed as a resist lower film, a silicon-containing resist intermediate film is formed thereon as a resist intermediate film, and a normal organic photoresist film is formed thereon as a resist upper film. When dry etching is performed using fluorine-based gas plasma, the organic resist upper film can achieve a good etching selectivity ratio with respect to the silicon-containing resist intermediate film, and therefore, the resist upper film pattern can be transferred to the silicon-containing resist intermediate film by dry etching using fluorine-based gas plasma. According to this method, even when a resist composition that is difficult to form a pattern with a sufficient film thickness for a substrate to be directly processed is used, or a resist composition that does not have sufficient dry etching resistance for substrate processing is used, if the pattern can be transferred to a silicon-containing resist intermediate film (resist intermediate film), and then the pattern transfer is performed by dry etching performed by oxygen-based or hydrogen-based gas plasma, a pattern of an organic film (resist underlayer film) made of novolac resin or the like having sufficient dry etching resistance for substrate processing can be obtained. As for the above-mentioned resist underlayer film, many are known, such as those described in Patent Document 1.

[0008] On the other hand, in recent years, the miniaturization of DRAM memory has accelerated, and there is a growing demand for resist underlayer films with improved dry etching resistance and excellent filling and planarization characteristics. Coating-type organic underlayer film materials with excellent filling and planarization characteristics, such as those described in Patent Document 2, have been reported, but it is expected that when the advanced generation is applied, there will be concerns about dry etching resistance, and the application limit of known coating-type organic underlayer film materials has been approached.

[0009] In order to solve the above-mentioned problem, Patent Document 3 reports that the etching resistance of the resist underlayer film during substrate processing has been improved by heating the resist underlayer film at a temperature of 450° C. to 800° C. in a gas atmosphere having an oxygen concentration of less than 1% by volume. However, many of the resist underlayer films used in the above-mentioned embodiments are resins or compounds containing hydroxyl groups or propargyl groups, and it is believed that oxygen atoms remain in the film, which is not ideal from the perspective of etching resistance.

[0010] Patent Document 4 reports a resist underlayer film material containing a condensed polycyclic polynuclear aromatic (COPNA) resin. The flatness of the cured film after treatment at 400°C is discussed, but there is no example of a cured film formed by baking in an inert gas at a temperature exceeding 500°C, and the change in etching resistance of the cured film formed by treatment under high temperature conditions in an inert gas is not clear.

[0011] Prior art literature

[0012] Patent Literature

[0013] [Patent Document 1] Japanese Patent Application Publication No. 2004-205685

[0014] [Patent Document 2] Japanese Patent Application Publication No. 2017-119671

[0015] [Patent Document 3] Japanese Patent Application Publication No. 2016-206676

[0016] [Patent Document 4] Japanese Patent Application Publication No. 2017-092457 Summary of the invention

[0017] [Problems to be solved by the invention]

[0018] In view of the above situation, the present invention aims to provide a composition for forming a resist underlayer film, which can form a resist underlayer film with extremely excellent dry etching resistance compared with known organic underlayer film materials, and to provide a pattern forming method using the composition for a resist underlayer film material, and a resist underlayer film forming method using the composition.

[0019] [Methods for solving problems]

[0020] In order to solve the above problems, the present invention provides a resist underlayer film-forming composition, characterized in that it contains (A) a polymer having a structure represented by the following general formula (1) as a repeating unit, and (B) an organic solvent.

[0021] The molecular weight of the polymer (A) is 300 to 3,000, and the polymer (A) does not contain a repeating unit containing a hydroxyl group as a substituent and does not contain a repeating unit containing a heteroaromatic ring.

[0022] [Chemistry 1]

[0023]

[0024] In the above formula (1), Ar is an unsubstituted divalent aromatic group having 6 to 30 carbon atoms.

[0025] If the composition for forming an anti-etching underlayer film contains a polymer (A) having a structure represented by the above-mentioned general formula (1), since the polymer (A) does not contain a polymer composed of repeating units having hydroxyl groups and / or heteroaromatic rings, a anti-etching underlayer film (high carbon film) with excellent dry etching resistance during substrate processing can be formed by, for example, thermal curing.

[0026] Furthermore, if the molecular weight is within the above range, not only is the solvent solubility excellent, but also good thermal decomposition can be exhibited by high temperature treatment. The resist underlayer film forming composition of the present invention promotes the dissociation and rebonding of carbon bonds of the polymer (A) by thermal decomposition, and becomes a diamond-like carbon structure, which can form a resist underlayer film with high carbon and excellent etching resistance.

[0027] The aromatic group Ar is preferably any of the following structures (1-a).

[0028] [Chemistry 2]

[0029]

[0030] In the above formula (1-a), * represents the bonding position to the methylene group (CH2) in the above general formula (1).

[0031] If the aromatic group Ar is any of the above structures (1-a), it contains a high carbon density aromatic ring and a methylene group that is easily thermally decomposed, thereby promoting the dissociation and rebonding of carbon bonds during high temperature treatment, thereby forming a resist underlayer film having a diamond-like carbon structure.

[0032] The aromatic group Ar is preferably any one of naphthalene, anthracene, phenanthrene, and pyrene.

[0033] It is preferred that the aromatic group Ar is any of naphthalene, anthracene, phenanthrene, and pyrene from the viewpoint of solvent solubility and productivity.

[0034] The polymer (A) is preferably a copolymer having two types of repeating units represented by the following general formula (2).

[0035] [Chemistry 3]

[0036]

[0037] In the above formula (2), Ar1 is any one of naphthalene, anthracene, phenanthrene, and pyrene, and Ar2 is a structure different from that of Ar1 and is any one selected from the following formula (1-a): a+b is 100, 30≤a≤99, 1≤b≤70.

[0038] [Chemistry 4]

[0039]

[0040] If the resist underlayer film forming composition contains the (A) polymer having a structure represented by the general formula (2), the solvent solubility can be improved while maintaining a high carbon composition.

[0041] In this case, the polymer (A) of the copolymer having two types of repeating units represented by the general formula (2) is preferably a polymerization reaction product of a monomer represented by the following formula (2-a) and a monomer represented by the following formula (2-b).

[0042] [Chemistry 5]

[0043] Ar1-CH2-X (2-a)

[0044] Ar2-CH2-X (2-b)

[0045] In the above formula, Ar1 is any one of naphthalene, anthracene, phenanthrene, and pyrene, Ar2 is a structure different from Ar1 and is any one selected from the above formula (1-a), and X is a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, or a halogen group.

[0046] If the polymer (A) obtained by the polymerization reaction of the monomers represented by the above formulas (2-a) and (2-b) is a polymer randomly containing different Ar structures, then when it is used as a resist underlayer film forming composition, a resist underlayer film forming composition with better solvent solubility can be provided.

[0047] Furthermore, Ar1 in the above formula (2) is more preferably anthracene.

[0048] The resist underlayer film forming composition in the above formula (2) in which Ar1 is anthracene is advantageous from the viewpoint of productivity in addition to the viewpoints of etching resistance and solvent solubility.

[0049] The molecular weight of the polymer (A) is preferably 300 to 1,500.

[0050] When the molecular weight of the polymer (A) is 300 to 1,500, a resist underlayer film-forming composition having excellent solvent solubility can be provided. Furthermore, when a resist underlayer film is formed using the composition, a resist underlayer film having excellent film thickness uniformity can be provided.

[0051] The aforementioned polymer (A) preferably has a terminal sealing group represented by the following general formula (3).

[0052] [Chemistry 6]

[0053]

[0054] In the above formula (3), * is a bonding portion with a methylene group in the above formula (1), d is an integer of 1-9, and e is an integer of 0-2.

[0055] If the resist underlayer film-forming composition contains the (A) polymer having the structure represented by the general formula (3), the adhesion with the substrate can be improved without deteriorating the dry etching resistance.

[0056] The resist underlayer film-forming composition preferably further contains (C) a blending resin which is a phenolic resin or a phenolic hydroxyl group-containing resin.

[0057] The resist underlayer film-forming composition containing such a phenolic resin or a phenolic hydroxyl group-containing resin can minimize the degradation of etching resistance after high-temperature treatment in a nitrogen atmosphere and improve film thickness uniformity.

[0058] In this case, the molecular weight of the (C) blended resin is more preferably 4,000 to 12,000.

[0059] When the resist underlayer film forming composition contains the blended resin (C) having a molecular weight within the above range, the uniformity of the film thickness after high-temperature treatment in a nitrogen atmosphere can be improved without deteriorating the filling property and / or planarization.

[0060] The amount of the blending resin (C) added is preferably 10 to 100 parts by mass based on 100 parts by mass of the polymer (A).

[0061] When the resist underlayer film forming composition contains 10 to 100 parts by mass of the (C) blended resin relative to 100 parts by mass of the (A) polymer, both film thickness uniformity and dry etching resistance after high temperature treatment in a nitrogen atmosphere can be achieved to a high degree.

[0062] Furthermore, the aforementioned (C) blended resin is preferably a resin represented by any of the following general formulas (C-1), (C-2) and (C-3).

[0063] [Chemistry 7]

[0064]

[0065] In the above formula (C-1), R is a monovalent to trivalent organic group having 1 to 20 carbon atoms which may contain an oxygen atom, o is an integer of 1 to 3, and p is an integer of 1 to 3.

[0066] [Chemistry 8]

[0067]

[0068] In the above formula (C-2), q is an integer of 0 or 1, and r is an integer of 1-6.

[0069] [Chemistry 9]

[0070]

[0071] In the above formula (C-3), s is an integer of 0 or 1, t is an integer of 1 to 6, and u is an integer of 0 or 1.

[0072] When the (C) blended resin has a structure represented by any of the above formulae (C-1) to (C-3), it is possible to achieve both uniformity of film thickness and etching resistance after high-temperature treatment in a nitrogen atmosphere at a higher level.

[0073] The resist underlayer film forming composition preferably further contains (D) a cross-linking agent having a structure represented by the following general formula (4).

[0074] [Chemistry 10]

[0075]

[0076] In the above formula (4), Ar3 and Ar4 are each a benzene ring or a naphthalene ring which may have a substituent, and R A represents a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, and W is a group represented by the following general formula (5).

[0077] [Chemistry 11]

[0078]

[0079] In the above formula (5), * represents a bonding position.

[0080] If the resist underlayer film forming composition contains a crosslinking agent having a structure represented by the general formula (4), a resist underlayer film forming composition having a higher crosslinking density can be provided. As a result, a resist underlayer film forming composition having a stronger etching resistance can be provided. Furthermore, by crosslinking the resist underlayer film before high-temperature treatment in a nitrogen environment, the uniformity of the film thickness during high-temperature treatment can be improved.

[0081] The resist underlayer film forming composition preferably further contains (E) a fluidity enhancer having a weight reduction rate of less than 30% at 30° C. to 190° C. and a weight reduction rate of 98% or more at 30° C. to 350° C.

[0082] The above-mentioned (E) fluidity promoter helps to improve the fluidity of the above-mentioned composition during coating and is removed from the film after baking at 350°C, so that the embedding property and / or flatness can be improved without deteriorating the etching resistance. In addition, it can also suppress the occurrence of defects caused by drying and can also contribute to improving the yield of semiconductor manufacturing.

[0083] In this case, the fluidity improving agent (E) preferably contains one or more compounds selected from the group consisting of compounds represented by the following general formulae (i) to (iii).

[0084] [Chemistry 12]

[0085]

[0086] In the above formula (i), R1 is independently a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms which may be substituted. W1 is a phenylene group or a divalent group represented by the following general formula (i-1). W2 and W3 are each a single bond or any divalent group represented by the following general formula (i-2). g is an integer of 1 to 5, and h is an integer of 0 to 10.

[0087] [Chemistry 13]

[0088]

[0089] In the above formula (i-1), * represents the bonding position, R 10 , R 11 , R 12 , and R 13 Each is a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms. 10 and W 11 Each independently represents a single bond or a carbonyl group. i and j are integers of 0 to 10, and i+j≥1.

[0090] [Chemistry 14]

[0091]

[0092] In the above formula (i-2), * represents a bonding position.

[0093] [Chemistry 15]

[0094]

[0095] In the above formula (ii), R2 is independently a hydrogen atom or an organic group having 1 to 10 carbon atoms which may be substituted. W4 is a divalent group represented by the following general formula (ii-1). W5 is a single bond or any divalent group represented by the following general formula (ii-2). k is an integer of 0 to 5, and l is an integer of 2 to 10.

[0096] [Chemistry 16]

[0097]

[0098] In the above formula (ii-1), * represents the bonding position, R 20 , R 21 , R 22 and R 23 Each is a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms. m and n are integers of 0 to 10, and m+n≥1.

[0099] [Chemistry 17]

[0100]

[0101] In the above formula (ii-2), * represents a bonding position.

[0102] [Chemistry 18]

[0103]

[0104] In the above formula (iii), R3 and R4 are each a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms which may be substituted, and may be bonded to form a cyclic structure. R5 and R6 are each an organic group having 1 to 10 carbon atoms, and R5 is a group containing an aromatic ring or one of the divalent groups represented by the following general formula (iii-1). W6 and W7 are each a single bond or any divalent group represented by the following general formula (iii-2), and at least one of them is a divalent group represented by any of (iii-2).

[0105] [Chemistry 19]

[0106]

[0107] In the above formula (iii-1), * represents the bonding position, W 30 It is an organic group having 1 to 4 carbon atoms.

[0108] [Chemistry 20]

[0109]

[0110] In the above formula (iii-2), * represents a bonding position.

[0111] By adding (E) a fluidity enhancer comprising one or more compounds selected from the general formulae (i) to (iii) to the polymer (A) to impart thermal fluidity, the resist underlayer film forming composition can have high filling properties and / or flatness.

[0112] The resist underlayer film forming composition further comprises

[0113] (F) surfactant,

[0114] (G) an acid generator, and

[0115] (H) Plasticizer

[0116] Preferably, at least one of the following is used.

[0117] If the resist underlayer film forming composition contains the above-mentioned additives, the resist underlayer film forming composition can be more excellent in coating property, etching resistance, filling property and / or planarity.

[0118] Furthermore, the present invention provides a pattern forming method, which is a method for forming a pattern on a processed substrate, characterized by comprising the following steps:

[0119] (I-1) applying the resist underlayer film forming composition of the present invention on a substrate to be processed to obtain a coating film, and heat-treating the coating film to form a resist underlayer film,

[0120] (I-2) forming a resist upper layer film on the resist lower layer film using a photoresist material,

[0121] (I-3) after pattern exposure of the resist upper layer film, developing with a developer to form a pattern on the resist upper layer film,

[0122] (I-4) using the patterned resist upper film as a mask, transferring the pattern to the resist lower film by dry etching, and

[0123] (I-5) The substrate to be processed is processed using the patterned resist underlayer film as a mask to form a pattern on the substrate to be processed.

[0124] The pattern forming method using the above-mentioned two-layer resist process can form a fine pattern on a workpiece (workpiece substrate).

[0125] Furthermore, the present invention provides a pattern forming method, which is a method for forming a pattern on a processed substrate, characterized by comprising the following steps:

[0126] (II-1) applying the resist underlayer film-forming composition of the present invention on a substrate to be processed to obtain a coating film, and heat-treating the coating film to form a resist underlayer film,

[0127] (II-2) forming a resist intermediate film on the resist underlayer film,

[0128] (II-3) forming a resist upper layer film on the resist intermediate film using a photoresist material,

[0129] (II-4) after pattern exposure of the resist upper layer film, developing with a developer to form a pattern on the resist upper layer film,

[0130] (II-5) using the patterned resist upper film as a mask, transferring the pattern to the resist intermediate film by dry etching,

[0131] (II-6) using the resist intermediate film to which the pattern has been transferred as a mask, transferring the pattern to the resist lower layer film by dry etching, and

[0132] (II-7) The substrate to be processed is processed using the patterned resist underlayer film as a mask to form a pattern on the substrate to be processed.

[0133] The pattern forming method using the three-layer resist process can form a fine pattern with high precision on a workpiece.

[0134] Furthermore, the present invention provides a pattern forming method, which is a method for forming a pattern on a processed substrate, characterized by comprising the following steps:

[0135] (III-1) applying the resist underlayer film-forming composition of the present invention on a substrate to be processed to obtain a coating film, and heat-treating the coating film to form a resist underlayer film,

[0136] (III-2) forming an inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film, and a silicon oxide nitride film on the resist underlayer film,

[0137] (III-3) forming an organic thin film on the aforementioned inorganic hard mask intermediate film,

[0138] (III-4) forming a resist upper layer film on the aforementioned organic thin film using a photoresist material,

[0139] (III-5) after pattern exposure of the resist upper layer film, developing with a developer to form a pattern on the resist upper layer film,

[0140] (III-6) using the patterned resist upper layer film as a mask, transferring the pattern to the organic thin film and the inorganic hard mask intermediate film by dry etching,

[0141] (III-7) using the inorganic hard mask intermediate film to which the pattern has been transferred as a mask, transferring the pattern to the resist underlayer film by dry etching, and

[0142] (III-8) The substrate to be processed is processed using the patterned resist underlayer film as a mask to form a pattern on the substrate to be processed.

[0143] By using the pattern forming method using the above-mentioned four-layer resist process, a fine pattern can be formed on a workpiece with high precision.

[0144] As the substrate to be processed, a substrate having a structure with a height of 30 nm or more or a height difference can be used.

[0145] The pattern forming method of the present invention is particularly useful for microfabrication of substrates having such structures or levels, since the resist underlayer film composition of the present invention is used to form a resist underlayer film having a high degree of filling property and / or flatness.

[0146] Furthermore, the present invention provides a method for forming an anti-etching underlayer film, which is a method for forming an anti-etching underlayer film that acts as an organic flat film used in the manufacturing step of a semiconductor device, and is characterized in that: the composition for forming an anti-etching underlayer film of the present invention is spin-coated on a processed substrate to obtain a coating film, and the coating film is heat-treated at a temperature in the range of 450°C to 800°C for 10 to 600 seconds to harden it and form a anti-etching underlayer film.

[0147] By using such a method, the crosslinking reaction during the formation of the resist lower film can be promoted, and the mixing with the resist upper film can be suppressed to a higher degree. In addition, by appropriately adjusting the heat treatment temperature, time and oxygen concentration within the above range, thermal decomposition can be promoted to form a film with excellent dry etching resistance.

[0148] Furthermore, the present invention provides a method for forming a resist underlayer film, which is a method for forming a resist underlayer film that acts as an organic flat film used in the manufacturing step of a semiconductor device, and is characterized in that: a coating film is obtained by spin-coating the resist underlayer film forming composition of the present invention on a processed substrate, and the coating film is hardened by heat treatment in a gas environment with an oxygen concentration of not less than 1% and not more than 21%, thereby forming a resist underlayer film.

[0149] By using such a method, the crosslinking reaction during the formation of the resist lower film can be promoted, and the mixing with the resist upper film can be suppressed to a higher degree. In addition, by appropriately adjusting the heat treatment temperature, time and oxygen concentration within the above range, thermal decomposition can be promoted to form a film with excellent dry etching resistance.

[0150] Furthermore, the present invention provides a method for forming a resist underlayer film, which is a method for forming a resist underlayer film that acts as an organic flat film used in the manufacturing step of a semiconductor device, and is characterized in that: a coating film is obtained by spin-coating the resist underlayer film forming composition of the present invention on a processed substrate, and the coating film is hardened by heat treatment in a gas environment with an oxygen concentration of less than 1%, thereby forming a resist underlayer film.

[0151] By using such a method, even if the substrate to be processed contains a component that is unstable to heating in an oxygen environment, the crosslinking reaction during the formation of the resist underlayer film can be promoted without causing degradation of the substrate to be processed, thereby forming a film with excellent dry etching resistance.

[0152] In this case, a substrate having a structure with a height of 30 nm or more or a height difference can be used as the aforementioned processed substrate.

[0153] The resist underlayer film forming method of the present invention uses the resist underlayer film material of the present invention which can form a resist underlayer film having a high degree of dry etching resistance and a high degree of filling property and / or flatness, and is therefore particularly suitable for forming a resist underlayer film on a substrate having such a structure or height difference.

[0154] [Effects of the Invention]

[0155] As described above, according to the resist underlayer film forming composition of the present invention, a resist underlayer film (high carbon film) having excellent dry etching resistance during substrate processing can be formed.

[0156] Furthermore, according to the pattern forming method of the present invention, a fine pattern can be formed on a workpiece with high precision.

[0157] Furthermore, according to the resist underlayer film forming method of the present invention, a film having excellent dry etching resistance can be formed.

[0158] Furthermore, the resist underlayer film forming composition, pattern forming method, and resist underlayer film forming method of the present invention are particularly suitable for multilayer resist processing including filling and / or flattening of a processed substrate with height difference and concave-convex, and are extremely useful in fine patterning for semiconductor device manufacturing. In particular, in the fine patterning processing using the multilayer resist method in the semiconductor device manufacturing step, even on the processed substrate with a dense part of a fine pattern structure with a high aspect ratio represented by a DRAM memory with a progress in miniaturization, which has a part difficult to fill and / or flatten, it is possible to fill without causing defects such as pores and peeling, and to form a resist underlayer film with excellent flatness characteristics. Moreover, it is possible to show better etching resistance than the known type of resist underlayer film without deteriorating the in-plane uniformity of the film thickness, and in particular, in a gas environment with an oxygen concentration of less than 1 volume%, heating at a temperature of 450°C to 800°C can exert its effect. Therefore, a fine pattern can be formed on the processed body with higher precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0159] Figure 1 (A) to (F) are explanatory diagrams of an example (three-layer resist process) of the pattern forming method of the present invention.

[0160] Figure 2 (Q) to (S) are explanatory diagrams of the landfill characteristic evaluation method.

[0161] Figure 3 (T) and (U) are explanatory diagrams of the planarization characteristic evaluation method. DETAILED DESCRIPTION

[0162] As described above, there is a demand for the development of a resist underlayer film forming composition used for forming a resist underlayer film capable of transferring a resist pattern to a substrate to be processed with higher precision in a fine patterning process using a multilayer resist method.

[0163] The inventors of the present application focused on a method for improving the dry etching resistance of a resist underlayer film during substrate processing by heating, for example, heating at a temperature of 450°C to 800°C in a gas atmosphere with an oxygen concentration of less than 1% by volume, and worked hard to develop a resist underlayer film-forming composition with greatly improved dry etching resistance using the above method. The inventors of the present application found that, unlike the resist underlayer film material having excellent heat resistance, if the thermal decomposition of the cured film by high-temperature baking is actively carried out, then, when heated at a temperature of 450°C to 800°C, for example, decomposition and re-bonding of carbon bonds occur, and the cured film becomes dense. The inventors of the present application have made further efforts to explore and found that if a polymer has a structure represented by the above general formula (1) composed only of carbon and hydrogen as a repeating unit but does not contain a repeating unit containing a hydroxyl group as a substituent and does not contain a repeating unit containing a heteroaromatic ring, then, for example, in a gas environment with an oxygen concentration of less than 1 volume %, when heated at a temperature of 450°C to 800°C, the resist underlayer film will densify and show extremely excellent dry etching resistance compared to known resist underlayer films, thereby completing the present invention.

[0164] That is, the present invention is a resist underlayer film-forming composition, which is characterized by:

[0165] (A) a polymer having a structure represented by the following general formula (1) as a repeating unit, and

[0166] (B) an organic solvent,

[0167] The molecular weight of the polymer (A) is 300 to 3,000, and the polymer (A) does not contain a repeating unit containing a hydroxyl group as a substituent and does not contain a repeating unit containing a heteroaromatic ring.

[0168] [Chemistry 21]

[0169]

[0170] In the above formula (1), Ar is an unsubstituted divalent aromatic group having 6 to 30 carbon atoms.

[0171] The present invention is described in detail below, but the present invention is not limited thereto.

[0172] <Resist Underlayer Film Forming Composition>

[0173] The composition for forming an anti-etching agent underlayer film of the present invention is characterized by containing (A) a polymer having a structure represented by the following general formula (1) as a repeating unit, and (B) an organic solvent, wherein the molecular weight of the aforementioned (A) polymer is 300 to 3,000, and the aforementioned (A) polymer does not contain a repeating unit containing a hydroxyl group as a substituent and does not contain a repeating unit containing a heteroaromatic ring.

[0174] [Chemistry 22]

[0175]

[0176] In the above formula (1), Ar is an unsubstituted divalent aromatic group having 6 to 30 carbon atoms.

[0177] If the composition for forming an anti-etching underlayer film is a polymer (A) that contains a structure having the formula (1) composed only of carbon and hydrogen as a repeating unit but does not contain a repeating unit containing a hydroxyl group as a substituent and does not contain a repeating unit containing a heteroaromatic ring, then the anti-etching underlayer film will be densified when fired at a high temperature in a nitrogen environment, and a anti-etching underlayer film showing excellent etching resistance can be formed.

[0178] The aromatic group Ar is preferably an unsubstituted divalent organic group having 6 to 30 carbon atoms, and more preferably any of the following structures (1-a).

[0179] [Chemistry 23]

[0180]

[0181] In the above formula (1-a), * represents the bonding position to the methylene group (CH2) in the above general formula (1).

[0182] The aromatic group Ar is preferably any of the above structure (1-a), but from the viewpoint of etching resistance and solvent solubility, and further from the viewpoint of productivity, any of naphthalene, anthracene, phenanthrene, and pyrene is particularly preferred. In view of the fact that the dissociation and rebonding of carbon bonds are easily promoted during high-temperature treatment in a nitrogen environment, and an amorphous carbon film can be formed, the aromatic group Ar is preferably naphthalene or anthracene, and anthracene is further preferred.

[0183] The molecular weight of the polymer (A) is 300 to 3,000, preferably 300 to 2,000, more preferably 300 to 1,500.

[0184] When the molecular weight of the polymer (A) is 300 to 3,000, the composition for forming a resist underlayer film can be excellent in solvent solubility, and a resist underlayer film can be formed with excellent film thickness uniformity after high-temperature firing in a nitrogen atmosphere. When the molecular weight is less than 300, a large amount of sublimates are produced during high-temperature treatment, and film thickness uniformity becomes poor. On the other hand, when the molecular weight is greater than 3,000, solvent solubility becomes poor.

[0185] When the aromatic group Ar is benzene, the molecular weight of the polymer (A) is preferably 500 to 3000. When the aromatic group Ar is naphthalene, the molecular weight of the polymer (A) is preferably 500 to 2500. When the aromatic group Ar is anthracene, the molecular weight of the polymer (A) is preferably 400 to 800. When the aromatic group Ar is phenanthrene, the molecular weight of the polymer (A) is preferably 400 to 800. When the aromatic group Ar is pyrene, the molecular weight of the polymer (A) is preferably 400 to 800.

[0186] The polymer (A) is preferably a copolymer having two types of repeating units represented by the following general formula (2).

[0187] [Chemistry 24]

[0188]

[0189] In the above formula (2), Ar1 is any one of naphthalene, anthracene, phenanthrene, and pyrene, Ar2 is a structure different from that of Ar1 and is any one selected from the above formula (1-a), and a+b is 100, 30≤a≤99, and 1≤b≤70.

[0190] In the above formula (2), Ar1 is any of naphthalene, anthracene, phenanthrene, and pyrene, but from the viewpoint that the dissociation and rebonding of carbon bonds are easily promoted during high-temperature treatment in a nitrogen environment, and an amorphous carbon film can be formed, Ar1 is preferably naphthalene or anthracene, and anthracene is more preferably. In the above formula (2), Ar2 is a structure different from Ar1, and when Ar1 is anthracene, Ar2 is preferably naphthalene, phenanthrene, or pyrene from the viewpoint of etching resistance, solvent solubility, and productivity.

[0191] In the above formula (2), the ranges of a and b are 30≤a≤99 and 1≤b≤70, and preferably 50≤a≤80 and 20≤b≤50 from the viewpoint of etching resistance and solvent solubility.

[0192] The polymer (A) of the copolymer having two types of repeating units represented by the general formula (2) is preferably a polymerization reaction product of a monomer represented by the following formula (2-a) and a monomer represented by the following formula (2-b).

[0193] [Chemistry 25]

[0194] Ar1-CH2-X (2-a)

[0195] Ar2-CH2-X (2-b)

[0196] In the above formula, Ar1 and Ar2 are the same as in formula (2), and X is a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, or a halogen group.

[0197] In the aforementioned formula (2-a) and the aforementioned formula (2-b), X is a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, or a halogen group. From the viewpoint of productivity and reactivity, a hydroxyl group or a methoxy group is preferred, and a hydroxyl group is even more preferred. In addition, in the monomers represented by the aforementioned formula (2-a) and the aforementioned formula (2-b), X may contain a hydroxyl group, but X will be separated by the polymerization reaction, so the polymer having the structure represented by the formula (2) of the polymerization reaction product of these monomers does not contain a hydroxyl group in the repeating unit.

[0198] The polymer (A) mentioned above preferably has a terminal sealing group represented by the following general formula (3).

[0199] [Chemistry 26]

[0200]

[0201] In the above formula (3), * is a bonding portion to the methylene group (CH2) in the above formula (1) or (2), d is an integer of 1 to 9, and e is an integer of 0 to 2.

[0202] In the above formula (3), d is an integer of 1 to 9, and e is an integer of 0 to 2. However, from the perspective of both etching resistance and solvent solubility / substrate adhesion, and further from the perspective of productivity, d is preferably 1 or 2, and e is preferably 0 or 1. In order to improve etching resistance, it is more desirable that d is smaller and e is larger, and in order to improve solvent solubility / substrate adhesion, it is more desirable that d is larger and e is smaller.

[0203] The polymer (A) may contain the terminal-sealing group represented by the formula (3) at the terminal, but the repeating unit constituting the polymer (A) does not contain a hydroxyl group.

[0204] [(A) First method for producing polymer]

[0205] The polymer (A) having the structure represented by formula (1) as a repeating unit can be obtained, for example, by the polycondensation reaction of an aromatic ring compound or a condensed aromatic ring compound represented by Ar' shown below with formaldehyde. Ar in the following formula is the same as that described above, and Ar' is an aromatic ring compound or a condensed aromatic ring compound having an unsubstituted aromatic ring with 6 to 30 carbon atoms.

[0206] [Chemistry 27]

[0207]

[0208] The aromatic ring compound or condensed aromatic ring compound used in the polycondensation reaction may be used alone or in combination of two or more. These compounds may be appropriately selected and combined depending on the required properties.

[0209] The polycondensation reaction can be generally carried out in an organic solvent in the presence of an acid catalyst at room temperature or under cooling or heating as required. Acid catalysts that can be used include inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, and heteropoly acids, organic acids such as oxalic acid, trifluoroacetic acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, and trifluoromethanesulfonic acid, aluminum trichloride, aluminum ethoxide, aluminum isopropoxide, boron trifluoride, boron trichloride, boron tribromide, tin tetrachloride, tin tetrabromide, dibutyltin dichloride, dimethoxydibutyltin, dibutyltin oxide, titanium tetrachloride, titanium tetrabromide, titanium (IV) methoxide, titanium (IV) ethoxide, titanium (IV) isopropoxide, and Lewis acids such as titanium (IV) oxide.

[0210] As for the acid catalyst, any of the above examples can be synthesized, but if a metal-containing Lewis acid is used for synthesis, it becomes difficult to remove the metal from the polymer. Therefore, a metal-free organic acid is preferred, and trifluoroacetic acid, methanesulfonic acid, benzenesulfonic acid, and p-toluenesulfonic acid are more preferred.

[0211] The organic solvent used in the polycondensation reaction includes, for example, alcohols such as methanol, ethanol, isopropanol, butanol, ethylene glycol, propylene glycol, diethylene glycol, glycerol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, etc., ethers such as diethyl ether, dibutyl ether, diethylene glycol diethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, 1,4-dioxane, etc., chlorine-based solvents such as dichloromethane, chloroform, dichloroethane, trichloroethylene, etc., hydrocarbons such as hexane, heptane, benzene, toluene, xylene, cumene, 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, and aprotic polar solvents such as dimethyl sulfoxide, N,N-dimethylformamide, and hexamethylphosphoric triamide, and the like. These can be used alone or in combination of two or more.

[0212] The reaction method includes, for example, a method of feeding the aromatic ring compound or condensed aromatic ring compound, formaldehyde, and an acid catalyst in batches, a method of dispersing or dissolving the aromatic ring compound or condensed aromatic ring compound and formaldehyde, and then adding the acid catalyst in batches or diluting with a solvent and adding dropwise, or a method of dispersing or dissolving the acid catalyst, and then adding the aromatic ring compound or condensed aromatic ring compound and formaldehyde in batches or diluting with a solvent and adding dropwise. After the reaction is completed, the organic film-forming composition of the present invention can be used directly, but in order to remove unreacted raw materials, acid catalysts, etc. present in the system, it can also be diluted in an organic solvent, separated and washed, and recovered.

[0213] The organic solvent used for separation and washing is not particularly limited as long as it can dissolve the compound and separate into two layers when mixed with water, for example, hydrocarbons such as hexane, heptane, benzene, toluene, xylene, esters such as ethyl acetate, n-butyl acetate, propylene glycol methyl ether acetate, ketones such as methyl ethyl ketone, methyl amyl ketone, cyclohexanone, methyl isobutyl ketone, ethers such as diethyl ether, diisopropyl ether, methyl-tert-butyl ether, ethylcyclopentyl methyl ether, chlorine-based solvents such as dichloromethane, chloroform, dichloroethane, trichloroethylene, and mixtures thereof.

[0214] The washing water used in the separation and washing is usually deionized water or ultrapure water. The washing frequency may be one or more, and even if the washing frequency is 10 or more, the effect may not be obtained, so the washing frequency is preferably about 1 to 5 times.

[0215] In order to remove the unreacted raw materials or acidic components in the system during liquid separation and washing, it can also be washed with an alkaline aqueous solution. Specifically, the alkali contained in the alkaline aqueous solution includes, for example, alkali metal hydroxides, alkali metal carbonates, alkaline earth metal hydroxides, alkaline earth metal carbonates, ammonia, and organic ammonium.

[0216] Furthermore, in order to remove unreacted raw materials, metal impurities or alkaline components in the system during liquid separation and washing, washing with an acidic aqueous solution can also be performed. Specifically, the acid contained in the acidic aqueous solution includes inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, and heteropoly acids, and organic acids such as oxalic acid, trifluoroacetic acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, and trifluoromethanesulfonic acid.

[0217] The above-mentioned liquid separation washing using alkaline aqueous solution and acidic aqueous solution can be performed alone or in combination. Liquid separation washing is preferably performed in order of washing with alkaline aqueous solution and acidic aqueous solution from the viewpoint of removing metal impurities.

[0218] After the above-mentioned separation and washing using alkaline aqueous solution and acidic aqueous solution, it can be washed with neutral water. The washing number can be more than 1 time, preferably about 1 to 5 times. Neutral water can be the above-mentioned deionized water, ultrapure water, etc. The washing number can be more than 1 time, and sometimes the alkaline component and acidic component cannot be removed if the number is less. Washing more than 10 times may not necessarily obtain the corresponding cleaning effect, so it is preferably about 1 to 5 times.

[0219] In addition, the reaction product after separation and washing can be recovered in the form of powder by concentrating the solvent to dryness or performing crystallization operation under reduced pressure or normal pressure, but in order to improve the operability when preparing the organic film forming composition, it can also be prepared in advance into a solution state of appropriate concentration. At this time, the concentration is preferably 0.1 to 50% by weight, and more preferably 0.5 to 30% by weight. If it is such a concentration, the viscosity is not easy to increase, thereby preventing damage to the operability, and the amount of the solvent will not become too large, so it is economical.

[0220] The solvent in this case is not particularly limited as long as it can dissolve the polymer. Specific examples include ketones such as cyclohexanone and methyl-2-pentanone; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; ethers such as propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; and esters such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol mono-tert-butyl ether acetate. These may be used alone or in combination of two or more.

[0221] [Second method for producing a polymer (alternative method 1)]

[0222] The polymer (A) having the structure represented by formula (1) as a repeating unit can be obtained by a second production method using a polymerization reaction of a raw material represented by Ar-CH2-X as an alternative method. Ar is the same as described above, and X is a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, or a halogen group.

[0223] [Chemistry 28]

[0224]

[0225] The polymerization reaction described above is a polymerization reaction that can obtain a polymer with a monomer alone. In the polycondensation reaction of the first manufacturing method, two common monomers A and B are used to utilize intermolecular dehydration reactions, etc. to form a general polymer having a form of repeating units from monomers A and B, but if it is the manufacturing method of the above-mentioned polymer, a homopolymer can be synthesized with one monomer. In the present invention, from the viewpoint of productivity, the second manufacturing method is preferred.

[0226] [First method for producing a polymer: monomers alternately form repeating units]

[0227] [Chemistry 29]

[0228]

[0229] [Second method for producing a polymer (alternative method 1): homopolymer of monomer A only]

[0230] [Chemistry 30]

[0231]

[0232] In the above-mentioned polymer synthesis reaction method, when two monomers (Ar and Ar") with different Ar are used as an example, as long as the monomers are fed in batches, a random polymer without specific repeating units can be synthesized. In addition, after synthesizing a polymer with a monomer having Ar in the first stage, a monomer having Ar" is fed in the second stage to synthesize a polymer with a block structure. These synthesis methods can be appropriately selected according to the required performance, etc.

[0233] [2 types of monomers: random type (batch feeding)]

[0234] [Chemistry 31]

[0235]

[0236] [2 types of monomers: block type (2-stage feed)]

[0237] [Chemistry 32]

[0238]

[0239] The polymer having two repeating units represented by formula (2) obtained by the above synthesis method is ideal because it can provide a composition for forming a resist underlayer film showing excellent solvent solubility compared to the polymer obtained by the following third synthesis method (Alternative Method 2). It is speculated that the excellent solvent solubility is achieved by randomly containing two different types of Ar and Ar".

[0240] [Method for producing polymer (Alternative method 2)]

[0241] [Chemistry 33]

[0242]

[0243] Ar', Ar1 and Ar2 are the same as described above, and X is a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, or a halogen group.

[0244] The polymer obtained by the third manufacturing method (method 2) becomes a polymer having repeating units of an aromatic ring compound or a condensed aromatic ring compound and X-CH2-Ar2-CH2-X arranged alternately. This synthesis method can also synthesize a homopolymer if Ar1 and Ar2 are raw materials with the same structure, but the disadvantage is that it is difficult to control the molecular weight. If the molecular weight cannot be controlled, the thermal decomposition behavior during high temperature treatment will change, and sometimes there is a risk of poor dry etching resistance.

[0245] [Monomers A and B alternately form repeating units]

[0246] [Chemistry 34]

[0247]

[0248] In the case of the above-mentioned polymer synthesis reaction method (second production method: alternative method 1), an aromatic component Ar that can react with the monomer may be introduced in the batch or during the reaction. x (Ar x The method for introducing these terminal sealing groups can be appropriately selected according to the reaction rate, etc. The known polymerization method can only be introduced at both ends due to the reactivity, but when this polymerization method is used, one terminal sealing unit can be introduced into one polymer molecule. Therefore, when polar groups such as hydroxyl groups are introduced to adjust the film-forming properties and adhesion when used as a resist lower film material by terminal sealing, it can be expected to achieve performance improvement with a minimum amount of introduction, so it has advantages from the perspective of etching resistance. On the other hand, when the repeating unit structure of the polymer contains polar groups such as hydroxyl groups, the heteroatom content is high, so even if high-temperature treatment causes dissociation and re-bonding of carbon bonds, there are still many heteroatoms remaining, and there is a risk that the dry etching resistance will become poor.

[0249] [End seal: introduced during reaction]

[0250] [Chemistry 35]

[0251]

[0252] [End seal: batch feeding]

[0253] [Chemistry 36]

[0254]

[0255] Aromatic components Ar x The following are mentioned, and these aromatic rings may have substituents such as vinyl, ethynyl, ethynylphenyl, allyl, propargyl, aryl, allyloxy, propargyloxy, etc. From the viewpoint of imparting etching resistance and solvent solubility, the organic group preferably has a naphthalene ring, a fluorene structure, or a carbazole structure.

[0256] [Chemistry 37]

[0257]

[0258] [Chemistry 38]

[0259]

[0260] [Chemistry 39]

[0261]

[0262] The polymer synthesis reaction shown in the second production method (alternative method 1) is different only in that a monomer represented by Ar-CH2-X is used, and the same reaction method and recovery method as those of the first production method can be used for production. The third production method (alternative method 2) is also the same.

[0263] <(B) Organic Solvent>

[0264] The (B) organic solvent that can be used in the resist underlayer film forming composition of the present invention is not particularly limited as long as it can dissolve the above-mentioned (A) polymer and can dissolve the (C) blending resin, (D) cross-linking agent, (E) fluidity promoter, (F) surfactant, (G) acid generator, (H) plasticizer, other additives, etc. that are optionally contained therein.

[0265] Specifically, for example, an organic solvent described in paragraphs

[0091] to

[0092] of Japanese Patent Application Laid-Open No. 2007-199653 may be added. Specifically, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, 2-heptanone, cyclopentanone, cyclohexanone and γ-butyrolactone, or a mixture containing one or more of these is preferably used.

[0266] The amount of the organic solvent to be added is preferably in the range of 200 to 10,000 parts, more preferably 250 to 5,000 parts, based on 100 parts by mass of the (A) polymer.

[0267] <(C) Blending Resin>

[0268] The resist underlayer film forming composition of the present invention preferably further contains (C) a blending resin of a phenolic resin or a phenolic hydroxyl group-containing resin.

[0269] The resist underlayer film forming composition contains the above-mentioned (C) blended resin having excellent thermosetting properties, so that the film thickness uniformity after high-temperature firing in a nitrogen atmosphere is further improved.

[0270] The molecular weight of the aforementioned (C) blended resin is preferably 4,000 to 12,000. From the viewpoint of embedding property and / or flatness and film thickness uniformity, the molecular weight of the (C) blended resin is preferably 6,000 to 10,000, and more preferably 7,000 to 9,000. If the molecular weight is 4,000 or more, the effect of improving the film thickness uniformity of the resist underlayer film can be fully obtained, and if the molecular weight is 12,000 or less, the embedding property and / or flatness of the resist underlayer film forming composition can be fully achieved.

[0271] The amount of the (C) blended resin added is preferably 10 to 100 parts by mass relative to 100 parts by mass of the (A) polymer. From the perspective of etching resistance and film thickness uniformity of the resist underlayer film after high temperature treatment in a nitrogen environment, the amount of the (C) blended resin added is preferably 20 to 80 parts by mass, and more preferably 40 to 60 parts by mass relative to 100 parts by mass of the (A) polymer.

[0272] The aforementioned (C) blended resin is preferably a resin represented by any of the following general formulas (C-1), (C-2) and (C-3).

[0273] [Chemistry 40]

[0274]

[0275] In the above formula (C-1), R is a monovalent to trivalent organic group having 1 to 20 carbon atoms which may contain an oxygen atom, o is an integer of 1 to 3, and p is an integer of 1 to 3.

[0276] [Chemistry 41]

[0277]

[0278] In the above formula (C-2), q is an integer of 0 or 1, and r is an integer of 1-6.

[0279] [Chemistry 42]

[0280]

[0281] In the above formula (C-3), s is an integer of 0 or 1, t is an integer of 1 to 6, and u is an integer of 0 or 1.

[0282] In the above formula (C-1), R is preferably a structure represented by the following formula (C-1a).

[0283] [Chemistry 43]

[0284]

[0285] In the above formula (C-1a), * represents a bonding position.

[0286] In the above formula (C-1), o is preferably 2 or 3, and more preferably 3. p is preferably 1 or 2, and more preferably 1. More specific examples of the compound represented by the above formula (C-1) include the following, but are not limited thereto.

[0287] [Chemistry 44]

[0288]

[0289] In the above formula (C-2), q is preferably 1, r is preferably 1 to 3, and r is more preferably 2 to 3.

[0290] More specifically, the compound represented by the above formula (C-2) includes the following, but is not limited thereto.

[0291] [Chemistry 45]

[0292]

[0293] In the above formula (C-3), s is preferably 1, t is preferably 1 to 3, more preferably t is 2 to 3, and u is preferably 1. More specific examples of the compound represented by the above formula (C-3) include the following, but are not limited thereto.

[0294] [Chemistry 46]

[0295]

[0296] <(D) Cross-linking agent>

[0297] The resist underlayer film forming composition of the present invention preferably further contains (D) a cross-linking agent having a structure represented by the following general formula (4).

[0298] [Chemistry 47]

[0299]

[0300] In the above formula (4), Ar3 and Ar4 are each a benzene ring or a naphthalene ring which may have a substituent, and R A represents a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, and W is a group represented by the following general formula (5).

[0301] [Chemistry 48]

[0302]

[0303] In the above formula (5), * represents a bonding position.

[0304] In the above formula (4), Ar3 and Ar4 are each a benzene ring or a naphthalene ring which may have a substituent, and R A represents a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, W is a group represented by the above formula (5), and from the viewpoint of raw material availability, W is preferably an unsubstituted benzene ring, and R A It is preferably a hydrogen atom or an n-butyl group.

[0305] The ratio Mw / Mn (i.e., the degree of dispersion) of the weight average molecular weight Mw and the number average molecular weight Mn of the crosslinking agent represented by the general formula (4) in terms of polystyrene obtained by gel permeation chromatography is preferably 1.00≤Mw / Mn≤1.25.

[0306] If the dispersion is within the above range, the thermal fluidity of the resist underlayer film-forming composition can be sufficient. When mixed in the resist underlayer film-forming composition, the fine structure formed on the substrate can be fully buried, and a resist underlayer film with a flat substrate can be formed. By definition, if it is a monomolecular compound, Mw / Mn is 1.00, but due to the separation of GPC, the measured value sometimes exceeds 1.00. In general, if a polymer having repeating units does not use a special polymerization method, it is extremely difficult to approach Mw / Mn=1.00, and it will have a distribution of Mw and become a value of Mw / Mn exceeding 1. In the present invention, in order to distinguish monomolecular compounds from polymers, 1.00≤Mw / Mn≤1.25 is defined as an indicator of monomolecularity.

[0307] In the above composition, the content of the crosslinking agent (D) is preferably 5 to 50 parts by mass, more preferably 10 to 40 parts by mass, and even more preferably 15 to 30 parts by mass, based on 100 parts by mass of the polymer (A).

[0308] <(E) Flowability Enhancer>

[0309] The resist underlayer film forming composition of the present invention preferably further contains a fluidity promoter (E) having a weight reduction rate of less than 30% at 30°C to 190°C and a weight reduction rate of 98% or more at 30°C to 350°C.

[0310] A fluidity enhancer having a weight loss rate of less than 30% between 30°C and 190°C and a weight loss rate of 98% or more between 30°C and 350°C is preferred because evaporation during heat treatment is suppressed, the viscosity is sufficiently kept low, the thermal fluidity is excellent, and the residual fluidity enhancer in the resist underlayer film after firing is small. In this specification, the weight loss rate is a value obtained by TG (thermogravimetric) measurement using a differential thermobalance.

[0311] The upper limit of the temperature range in which the weight loss rate of the fluidity promoter (E) does not reach 30% is preferably 210° C., and more preferably 230° C. When the weight loss rate of the fluidity promoter (E) does not reach 30% is within the above temperature range, the filling property and / or flatness can be further improved.

[0312] The temperature at which the weight reduction rate of the fluidity enhancer (E) reaches 98% or more is preferably 330° C., and particularly preferably 310° C. When the weight reduction rate of the fluidity enhancer reaches 98% or more in the above temperature range, the residual fluidity enhancer in the resist underlayer film after firing can be reduced.

[0313] By adding the above-mentioned (E) fluidity promoter, the thermal fluidity of the resist underlayer film-forming composition from the start of heat treatment to the hardening due to the crosslinking reaction is improved, so that better filling properties and / or better flatness can be achieved. On the other hand, the (E) fluidity promoter is reduced by evaporation due to heat treatment, so that etching resistance and optical properties are not impaired.

[0314] In a more preferred embodiment of the fluidity improver (E), for example, one or more compounds selected from the group consisting of compounds represented by the following general formulae (i) to (iii).

[0315] [Chemistry 49]

[0316]

[0317] In the above formula (i), R1 is independently a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms which may be substituted. W1 is a phenylene group or a divalent group represented by the following general formula (i-1). W2 and W3 are each a single bond or any divalent group represented by the following general formula (i-2). g is an integer of 1 to 5, and h is an integer of 0 to 10.

[0318] [Chemistry 50]

[0319]

[0320] In the above formula (i-1), * represents the bonding position, R 10 , R 11 , R 12 , R 13 W is a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms. 10 and W 11 Each independently represents a single bond or a carbonyl group. i and j are integers of 0 to 10, and i+j≥1.

[0321] [Chemistry 51]

[0322]

[0323] In the above formula (i-2), * represents a bonding position.

[0324] [Chemistry 52]

[0325]

[0326] In the above formula (ii), R2 is independently a hydrogen atom or an organic group having 1 to 10 carbon atoms which may be substituted. W4 is a divalent group represented by the following general formula (ii-1). W5 is a single bond or any divalent group represented by the following general formula (ii-2). k is an integer of 0 to 5, and l is an integer of 2 to 10.

[0327] [Chemistry 53]

[0328]

[0329] In the above formula (ii-1), * represents the bonding position, R 20 , R 21 , R 22 and R 23 Each is a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms. m and n are integers of 0 to 10, and m+n≥1.

[0330] [Chemistry 54]

[0331]

[0332] In the above formula (ii-2), * represents a bonding position.

[0333] [Chemistry 55]

[0334]

[0335] In the above formula (iii), R3 and R4 are each a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms which may be substituted, and may be bonded to form a cyclic structure. R5 and R6 are each an organic group having 1 to 10 carbon atoms, and R5 is a group containing an aromatic ring or one of the divalent groups represented by the following general formula (iii-1). W6 and W7 are each a single bond or any divalent group represented by the following general formula (iii-2), and at least one of them is a divalent group represented by any of (iii-2).

[0336] [Chemistry 56]

[0337]

[0338] In the above formula (iii-1), * represents the bonding position, W 30 It is an organic group having 1 to 4 carbon atoms.

[0339] [Chemistry 57]

[0340]

[0341] In the above formula (iii-2), * represents a bonding position.

[0342] In the above general formula (i), R1 is independently a hydrogen atom, a hydroxyl group, or an optionally substituted organic group having 1 to 10 carbon atoms.

[0343] Here, in the present invention, the "organic group" refers to a group containing at least one carbon atom, further containing hydrogen, and, unless otherwise specified, may also contain nitrogen, oxygen, sulfur, silicon, halogen atoms, etc.

[0344] R1 may be a single type or a mixture of multiple types. More specifically, R1 includes, for example, a hydrogen atom, a hydroxyl group, a methyl group, an ethyl group, a vinyl group, a 2,2,2-trifluoroethyl group, a propyl group, an isopropyl group, an allyl group, a butyl group, a sec-butyl group, a tert-butyl group, an isobutyl group, a pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a cyclohexenyl group, a decyl group, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a sec-butoxy group, a norbornyl group, an adamantyl group, a phenyl group, a toluoyl group, a xylyl group, a naphthyl group, a benzyl group, a 2-furanyl group, and a 2-tetrahydrofuranyl group. Among R1, a hydrogen atom is more preferred.

[0345] W1 is a phenylene group or a divalent group represented by the above general formula (i-1). W2 and W3 are each a single bond or an arbitrary divalent group represented by the following general formula (i-2). h is an integer of 0 to 10, and g is an integer of 1 to 5, each independently.

[0346] In the above formula (i-1), R 10 , R 11 , R 12 and R 13 , more specifically, for example, a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms. More specifically, a hydrogen atom, a hydroxyl group, a methyl group, an ethyl group, a vinyl group, a 2,2,2-trifluoroethyl group, a propyl group, an isopropyl group, an allyl group, a butyl group, a sec-butyl group, a tert-butyl group, an isobutyl group, a pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a cyclohexenyl group, a decyl group, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a sec-butoxy group, a butoxy group, a norbornyl group, an adamantyl group, a phenyl group, a toluoyl group, a xylyl group, a naphthyl group, a benzyl group, a 2-furyl group, and a 2-tetrahydrofuranyl group. Among them, R 10 , R 11 , R 12 and R 13 Each is preferably a hydrogen atom or a methyl group, and more preferably a hydrogen atom.

[0347] W 10 and W 11 Each is independently a single bond or a carbonyl group. i and j are integers of 0 to 10, and i+j≥1.

[0348] In the above formula (ii), R2 can be a single type or a mixture of multiple types. More specifically, R2 can be, for example, a hydrogen atom, a hydroxyl group, a methyl group, an ethyl group, a vinyl group, a 2,2,2-trifluoroethyl group, a propyl group, an isopropyl group, an allyl group, a butyl group, a sec-butyl group, a tert-butyl group, an isobutyl group, a pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a cyclohexenyl group, a decyl group, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a sec-butoxy group, a norbornyl group, an adamantyl group, a phenyl group, a toluoyl group, a xylyl group, a naphthyl group, a benzyl group, a 2-furanyl group, and a 2-tetrahydrofuranyl group. Among them, R2 is preferably a hydrogen atom.

[0349] In the above formula (ii), W4 is a divalent group represented by the above general formula (ii-1). W5 is a single bond or any divalent group represented by the above general formula (ii-2). k is an integer of 0 to 5, and l is an integer of 2 to 10.

[0350] In the above formula (ii-1), R 20 , R 21 , R 22 , and R 23 More specifically, for example, a hydrogen atom, a hydroxyl group, a methyl group, an ethyl group, a vinyl group, a 2,2,2-trifluoroethyl group, a propyl group, an isopropyl group, an allyl group, a butyl group, a sec-butyl group, a tert-butyl group, an isobutyl group, a pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a cyclohexenyl group, a decyl group, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a sec-butoxy group, a norbornyl group, an adamantyl group, a phenyl group, a toluoyl group, a xylyl group, a naphthyl group, a benzyl group, a 2-furyl group, and a 2-tetrahydrofuranyl group. 20 , R 21 , R 22 , and R 23 Each is preferably a hydrogen atom or a methyl group, and more preferably a hydrogen atom.

[0351] In the above formula (ii-1), m and n are integers of 0 to 10, and m+n≥1.

[0352] In the above formula (iii), R3 and R4 are each a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms. More specifically, for example, a hydrogen atom, a hydroxyl group, a methyl group, an ethyl group, a vinyl group, a 2,2,2-trifluoroethyl group, a propyl group, an isopropyl group, an allyl group, a butyl group, a sec-butyl group, a tert-butyl group, an isobutyl group, a pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a cyclohexenyl group, a decyl group, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a sec-butoxy group, a norbornyl group, an adamantyl group, a phenyl group, a toluoyl group, a xylyl group, a naphthyl group, a benzyl group, a 2-furyl group, or a 2-tetrahydrofuranyl group. Among them, R3 and R4 are each preferably a hydrogen atom.

[0353] In the above formula (iii), R6 is an organic group having 1 to 10 carbon atoms. In the above formula (iii), R5 is an organic group having 1 to 10 carbon atoms and is a group containing an aromatic ring or one of the divalent groups represented by the above general formula (iii-1). Examples of the organic group having 1 to 10 carbon atoms include the groups exemplified for R3 and R4 above.

[0354] In the above formula (iii), W6 and W7 are each a single bond or any divalent group represented by the following general formula (iii-2), and at least one of them is a divalent group represented by any of (iii-2).

[0355] In the above formula (iii-1), W 30is an organic group having 1 to 4 carbon atoms. More specifically, for example, methylene, ethylene, propylene, butylene, trimethylene, and tetramethylene. 30 More preferably, it is ethylene.

[0356] More specifically, the compound represented by the general formula (i) is exemplified below, but is not limited thereto.

[0357] [Chemistry 58]

[0358]

[0359] More specifically, the compound represented by the general formula (ii) is exemplified below, but is not limited thereto.

[0360] [Chemistry 59]

[0361]

[0362] More specifically, the compound represented by the general formula (iii) is exemplified below, but is not limited thereto.

[0363] [Chemistry 60]

[0364]

[0365] If the film-forming properties of the resist underlayer film-forming composition, the filling properties and / or flatness of the substrate, etc. are comprehensively considered, the (E) fluidity promoter used in the resist underlayer film-forming composition of the present invention is preferably an aromatic compound having a benzyl group or a benzoyl group, especially the aromatic compound described below.

[0366] (Ei) (Poly)ethylene glycol dibenzoate

[0367] (E-ii) (Poly)ethylene glycol dibenzyl ether

[0368] (E-iii) (Poly)propylene glycol dibenzyl ether

[0369] (E-iv) (Poly)butylene glycol dibenzyl ether

[0370] (Ev) Straight-chain aliphatic dicarboxylic acid dibenzyl ester

[0371] (E-vi) (Poly)ethylene glycol monobenzyl ether

[0372] (E-vii) (Poly)phenylene ether

[0373] [Chemistry 61]

[0374]

[0375] In addition, n in the above formula is an integer within the range of molecular weight of 500 or less, and is applicable only to this formula.

[0376] The (E) fluidity enhancer used in the resist underlayer film forming composition of the present invention has a structure having both a hydrophobic portion composed of an aromatic ring and a hydrophilic portion (for example, composed of the following (iii-1) structure), so it has excellent compatibility with (A) polymer, (B) organic solvent, and other additives, and can improve the fluidity of the composition without impairing film-forming properties and storage stability.

[0377] [Chemistry 62]

[0378]

[0379] In the formula, * indicates the bonding position, W 30 It is an organic group having 1 to 4 carbon atoms.

[0380] (E) The amount of the fluidity promoter blended is preferably 5 to 100 parts by mass, more preferably 10 to 50 parts by mass, relative to 100 parts by mass of the polymer. If the amount of the fluidity promoter blended is 10% by mass or more, the fluidity of the resist underlayer film-forming composition can be sufficiently improved. When the content of the fluidity promoter relative to the polymer is too low, the effect of improving the thermal fluidity of the resist underlayer film may be too low, while when the content of the fluidity promoter is excessive, there is a possibility that the film-forming property and dry etching resistance of the obtained coating film will be adversely affected.

[0381] As the fluidity improving agent (E), the above aromatic-containing compounds may be used alone or in combination of two or more.

[0382] <Other ingredients>

[0383] [Other crosslinking agents]

[0384] Furthermore, in the resist underlayer film forming composition of the present invention, in addition to the crosslinking agent (D) characterized by the structure of the above-mentioned general formula (4), a general crosslinking agent may also be added. The crosslinking agent used is not particularly limited, and crosslinking agents of various known systems can be widely used. For example, hydroxymethyl or alkoxymethyl type crosslinking agents of polynuclear phenols (polynuclear phenol crosslinking agents), melamine crosslinking agents, glycoluril crosslinking agents, benzoguanamine crosslinking agents, urea crosslinking agents, β-hydroxyalkylamide crosslinking agents, isocyanurate crosslinking agents, aziridine crosslinking agents, oxazoline crosslinking agents, and epoxy crosslinking agents. The amount of the crosslinking agent added is preferably 1 to 50 parts, more preferably 5 to 30 parts, relative to 100 parts by mass of the aforementioned (A) polymer.

[0385] Specific examples of the melamine-based crosslinking agent include hexamethoxymethylated melamine, hexabutoxymethylated melamine, alkoxy and / or hydroxyl-substituted melamines thereof, and partially self-condensed products thereof.

[0386] Specific examples of the glycoluril-based crosslinking agent include tetramethoxymethyl glycoluril, tetrabutoxymethyl glycoluril, alkoxy and / or hydroxyl-substituted products thereof, and partial self-condensation products thereof.

[0387] Specific examples of the benzoguanamine-based crosslinking agent include tetramethoxymethylated benzoguanamine, tetrabutoxymethylated benzoguanamine, alkoxy and / or hydroxyl-substituted products thereof, and partial self-condensation products thereof.

[0388] Specific examples of the urea crosslinking agent include dimethoxymethylated dimethoxyethylene urea, alkoxy and / or hydroxyl-substituted products thereof, and partial self-condensates thereof.

[0389] Specific examples of the β-hydroxyalkylamide crosslinking agent include N,N,N',N'-tetrakis(2-hydroxyethyl)adipamide. Specific examples of the isocyanurate crosslinking agent include triglycidyl isocyanurate and triallyl isocyanurate.

[0390] Specific examples of the aziridine crosslinking agent include 4,4′-bis(ethyleneiminocarbonylamino)diphenylmethane and 2,2-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate].

[0391] Oxazoline crosslinking agents include, for example, 2,2'-isopropylidenebis(4-benzyl-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-tert-butyl-2-oxazoline, 2,2'-bis(2-oxazoline), 1,3-phenylenebis(2-oxazoline), 1,4-phenylenebis(2-oxazoline), and 2-isopropenyloxazoline copolymers.

[0392] Specific examples of the epoxy crosslinking agent 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.

[0393] The polynuclear phenol-based crosslinking agent is specifically, for example, a compound represented by the following general formula (XL-1).

[0394] [Chemistry 63]

[0395]

[0396] In the formula, Q is a single bond or a q having 1 to 20 carbon atoms. c Valence hydrocarbon group. 3c is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. c It is an integer from 1 to 5.

[0397] Q is a single bond, or a carbon number of 1 to 20 c Hydroxyl. c is an integer of 1 to 5, preferably 2 or 3. Q is specifically, for example, methane, ethane, propane, butane, isobutane, pentane, cyclopentane, hexane, cyclohexane, methylpentane, methylcyclohexane, dimethylcyclohexane, trimethylcyclohexane, benzene, toluene, xylene, ethylbenzene, ethylisopropylbenzene, diisopropylbenzene, methylnaphthalene, ethylnaphthalene, or eicosane. c A group with 10 hydrogen atoms. 3c is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. Specifically, the alkyl group having 1 to 20 carbon atoms includes, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, hexyl, octyl, ethylhexyl, decyl, and eicosyl. 3c It is preferably a hydrogen atom or a methyl group.

[0398] Examples of compounds represented by the general formula (XL-1) include the following compounds. Among them, hexamethoxymethylated compounds of trisphenolmethane, trisphenolethane, 1,1,1-tris(4-hydroxyphenyl)ethane, and tris(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene are preferred from the viewpoint of improving the curability and film thickness uniformity of the organic film. 3c Same as above.

[0399] [Chemistry 64]

[0400]

[0401] [Chemistry 65]

[0402]

[0403] [(F) Surfactant]

[0404] In order to improve the coating property of spin coating, a surfactant may be added to the resist underlayer film forming composition of the present invention. The surfactant may be, for example, the surfactants described in

[0142] to

[0147] in Japanese Patent Application Publication No. 2009-269953. The amount of the surfactant added is preferably 0.01 to 10 parts, more preferably 0.05 to 5 parts, relative to 100 parts by mass of the polymer (A).

[0405] [(G) Acid generator]

[0406] In order to further promote the curing reaction, an acid generator may be added to the resist underlayer film forming composition of the present invention. Acid generators may generate acid by thermal decomposition or by light irradiation, and both may be added. Specifically, materials described in paragraphs

[0061] to

[0085] of Japanese Patent Application Publication No. 2007-199653 may be added, but the present invention is not limited thereto.

[0407] The acid generator may be used alone or in combination of two or more. The amount of the acid generator added is preferably 0.05 to 50 parts, more preferably 0.1 to 10 parts, based on 100 parts by mass of the polymer (A).

[0408] [(H) Plasticizer]

[0409] In addition, in the resist underlayer film forming composition of the present invention, a plasticizer may be added in order to further improve the embedding property and / or flatness. The plasticizer is not particularly limited, and plasticizers of various known systems can be widely used. For example, low molecular weight compounds such as phthalates, adipic acid esters, phosphates, trimellitic acid esters, and citrates, polyethers, polyesters, and polymers such as polyacetal polymers recorded in Japanese Patent Publication No. 2013-253227. The amount of the plasticizer added is preferably 1 to 100 parts, and more preferably 5 to 30 parts, relative to 100 parts by mass of the aforementioned (A) polymer.

[0410] In the resist underlayer film forming composition of the present invention, as an additive for imparting embedding property and / or flatness similarly to a plasticizer, for example, a liquid additive having a polyethylene glycol or polypropylene glycol structure, or a pyrolyzable polymer having a weight loss rate of 40% by mass or more between 30° C. and 250° C. and a weight average molecular weight of 300 to 200,000 is preferably used. The pyrolyzable polymer preferably contains a repeating unit having an acetal structure represented by the following general formula (DP1) or (DP1a).

[0411] [Chemistry 66]

[0412]

[0413] In the formula, R6' is a hydrogen atom or an optionally substituted saturated or unsaturated monovalent organic group having 1 to 30 carbon atoms. Y is a saturated or unsaturated divalent organic group having 2 to 30 carbon atoms.

[0414] [Chemistry 67]

[0415]

[0416] In the formula, R 6a Y is an alkyl group having 1 to 4 carbon atoms. aIt is a saturated or unsaturated divalent hydrocarbon group having 4 to 10 carbon atoms, and may have an ether bond. n represents the average number of repeating units, and is 3 to 500.

[0417] <Pattern Formation Method Using Resist Underlayer Film Forming Composition>

[0418] <Pattern Formation Method Using Resist Underlayer Film Forming Composition>

[0419] Furthermore, the present invention provides a pattern forming method, which is a method for forming a pattern on a processed substrate, characterized by comprising the following steps:

[0420] (I-1) applying the resist underlayer film forming composition onto a substrate to be processed to obtain a coating film, and heat-treating the coating film to form a resist underlayer film,

[0421] (I-2) forming a resist upper layer film on the resist lower layer film using a photoresist material,

[0422] (I-3) after pattern exposure of the resist upper layer film, developing with a developer to form a pattern on the resist upper layer film,

[0423] (I-4) using the patterned resist upper film as a mask, transferring the pattern to the resist lower film by dry etching, and

[0424] (I-5) The substrate to be processed is processed using the patterned resist underlayer film as a mask to form a pattern on the substrate to be processed.

[0425] By using the pattern forming method using the two-layer resist process, a fine pattern can be formed on a workpiece (workpiece substrate).

[0426] Furthermore, the present invention provides a pattern forming method, which is a method for forming a pattern on a processed substrate, characterized by comprising the following steps:

[0427] (II-1) applying the resist underlayer film-forming composition onto a substrate to be processed to obtain a coating film, and heat-treating the coating film to form a resist underlayer film,

[0428] (II-2) forming a resist intermediate film on the resist underlayer film,

[0429] (II-3) forming a resist upper layer film on the resist intermediate film using a photoresist material,

[0430] (II-4) after pattern exposure of the resist upper layer film, developing with a developer to form a pattern on the resist upper layer film,

[0431] (II-5) using the patterned resist upper film as a mask, transferring the pattern to the resist intermediate film by dry etching,

[0432] (II-6) using the resist intermediate film to which the pattern has been transferred as a mask, transferring the pattern to the resist lower layer film by dry etching, and

[0433] (II-7) The substrate to be processed is processed using the patterned resist underlayer film as a mask to form a pattern on the substrate to be processed.

[0434] According to the pattern forming method using the three-layer resist process, a fine pattern can be formed on a workpiece with high precision.

[0435] use Figure 1 An example of a method for forming a pattern using a three-layer resist process is described below. Figure 1 Specifically, first, the resist underlayer film-forming composition of the present invention is applied on the processed layer 2 of the processed substrate 1A including the supporting substrate 1 and the processed layer 2 formed thereon to obtain a coating film, and the coating film is heat-treated to form a resist underlayer film 3. Then, a resist intermediate film material is used to form a resist intermediate film 4 on the resist underlayer film 3. Then, a photoresist material is used to form a resist upper film 5 on the resist intermediate film 4. Then, as Figure 1 (B), an exposed portion 6 is formed in the resist upper film 5 by pattern exposure. Then, the exposed portion 6 is developed with a developer, and Figure 1 (C) is to form a resist upper film pattern 5a on the resist upper film 5. Then, the resist upper film 5 having the pattern 5a formed thereon is used as a mask and dry etching is performed. Figure 1 (D) , transfer the resist intermediate film pattern 4a containing silicon to the resist intermediate film 4. Then, using the resist intermediate film 4 to which the pattern 4a has been transferred as a mask, dry etching is performed, such as Figure 1 (E), the resist lower film pattern 3a is transferred to the resist lower film 3. Then, the resist lower film 3 having the pattern 3a formed thereon is used as a mask to process the processed layer 2 of the processed substrate 1A, as shown in FIG. Figure 1 (F) , forming a pattern 2a on the aforementioned processed substrate 1.

[0436] The silicon-containing resist intermediate film in the above-mentioned three-layer resist treatment shows resistance to etching by oxygen-based gases. Therefore, in the above-mentioned three-layer resist treatment, dry etching of the resist lower film using the silicon-containing resist intermediate film as a mask is preferably performed using an etching gas containing oxygen-based gases as the main component.

[0437] It is also ideal to use a polysiloxane-based interlayer for the silicon-containing resist intermediate film in the above-mentioned three-layer resist treatment. By giving the silicon-containing resist intermediate film an anti-reflection effect, reflection can be suppressed. In particular, for 193nm exposure, if a material containing many aromatic groups and having a high etching selectivity with the substrate is used for the organic film, the k value is high and the substrate reflection is high, but by giving the silicon-containing resist intermediate film an absorption with an appropriate k value, reflection can be suppressed and the substrate reflection can be reduced to less than 0.5%. For the silicon-containing resist intermediate film with an anti-reflection effect, it is ideal to use anthracene for 248nm and 157nm exposure, and to use a polysiloxane with a pendant phenyl group or a light-absorbing group with a silicon-silicon bond for 193nm exposure, and cross-linked with acid or heat.

[0438] Furthermore, the present invention provides a pattern forming method as a pattern forming method using a four-layer resist process using such a resist underlayer film forming composition, which is characterized by comprising the following steps:

[0439] (III-1) applying the resist underlayer film-forming composition of the present invention on a substrate to be processed to obtain a coating film, and heat-treating the coating film to form a resist underlayer film,

[0440] (III-2) forming an inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film, and a silicon oxide nitride film on the resist underlayer film,

[0441] (III-3) forming an organic thin film on the aforementioned inorganic hard mask intermediate film,

[0442] (III-4) forming a resist upper layer film on the aforementioned organic thin film using a photoresist material,

[0443] (III-5) after pattern exposure of the resist upper layer film, developing with a developer to form a pattern on the resist upper layer film,

[0444] (III-6) using the patterned resist upper layer film as a mask, transferring the pattern to the organic thin film and the inorganic hard mask intermediate film by dry etching,

[0445] (III-7) using the inorganic hard mask intermediate film to which the pattern has been transferred as a mask, transferring the pattern to the resist underlayer film by dry etching, and

[0446] (III-8) The substrate to be processed is processed using the patterned resist underlayer film as a mask to form a pattern on the substrate to be processed.

[0447] Furthermore, an inorganic hard mask may be formed instead of forming a silicon-containing resist intermediate film. In this case, a resist underlayer film can be formed at least on a workpiece using the resist underlayer film forming composition of the present invention, an inorganic hard mask selected from silicon oxide film, silicon nitride film, and silicon oxide nitride film is formed on the resist underlayer film, a resist upper film is formed on the inorganic hard mask using a photoresist composition, a circuit pattern is formed on the resist upper film, the patterned resist upper film is used as a mask, the inorganic hard mask is etched, the patterned inorganic hard mask is used as a mask, the resist underlayer film is etched, and the patterned resist underlayer film is used as a mask to etch the workpiece and form a pattern on the workpiece, so as to form a circuit pattern of a semiconductor device on the substrate.

[0448] As described above, when an inorganic hard mask is formed on the resist underlayer film, a silicon oxide film, a silicon nitride film, and a silicon oxide nitride film (SiON film) can be formed by using a CVD method, an ALD method, or the like. For example, a method for forming a silicon nitride film is described in Japanese Patent Application Publication No. 2002-334869 and International Publication No. 2004 / 066377. The film thickness of the inorganic hard mask is preferably 5 to 200 nm, and more preferably 10 to 100 nm. In addition, as an inorganic hard mask, it is best to use a SiON film that has a high effect as an anti-reflective film. The substrate temperature when forming the SiON film is 300 to 500°C, and the resist underlayer film needs to withstand a temperature of 300 to 500°C. The resist underlayer film forming composition used in the present invention has high heat resistance and can withstand high temperatures of 300°C to 500°C, so it can be a combination of an inorganic hard mask formed by CVD or ALD and a resist underlayer film formed by spin coating.

[0449] As described above, a photoresist film can be formed on the inorganic hard mask as a resist upper layer film, and an organic antireflection film (BARC) or a bonding film can be formed on the inorganic hard mask by spin coating and a photoresist film can be formed thereon. In particular, when a SiON film is used as an inorganic hard mask intermediate film, the two-layer antireflection film of the SiON film and the BARC can suppress reflection even in immersion exposure with a high NA exceeding 1.0. Another benefit of forming a BARC is that it has the effect of reducing the tailing of the photoresist pattern directly on the SiON film.

[0450] In the above pattern forming method, the resist upper layer film may be positive or negative, and the same photoresist composition as commonly used may be used. In addition, the photoresist composition may also contain metal atoms such as Sn, In, Ga, Ge, Al, Ce, La, Cs, Zr, Hf, Ti, Bi, Sb, and Zn. When the resist upper layer film is formed using the above photoresist composition, it may be formed by a spin coating method, a CVD method, or an ALD method by vapor deposition.

[0451] When the resist upper layer is formed by spin coating, the resist is pre-baked after coating, preferably at 60 to 180° C. for 10 to 300 seconds. After that, exposure is performed according to the usual method, and post-exposure baking (PEB) and development are performed to obtain a resist pattern. In addition, the thickness of the resist upper layer is not particularly limited, but 10 to 500 nm, especially 20 to 400 nm, is preferred.

[0452] When the resist upper layer is formed by vapor deposition by CVD or ALD, the resist composition is a metal oxide film with EUV sensitivity, and the metal is selected from Sn, Zr, Hf, Ti, Bi, Sb, etc., among which Sn with excellent EUV sensitivity is preferred. The film containing metal oxide can be a photosensitive organic metal oxide film such as organic tin oxide (for example, halogenated alkyl Sn, alkoxyalkyl Sn, or amide alkyl Sn). Some specific examples of suitable precursors include trimethyltin chloride, dimethyltin dichloride, methyltin trichloride, tris(dimethylamino)methyltin(IV), and (dimethylamino)trimethyltin(IV).

[0453] Metal oxide films can be deposited by PECVD or PEALD using a Lam Vector (registered trademark) tool, for example. In the ALD embodiment, the Sn oxide precursor can be separated from the O precursor / plasma. The evaporation temperature is preferably in the range of 50°C to 600°C. The evaporation pressure is preferably between 100 and 6,000 mTorr. The flow rate of the precursor liquid of the metal oxide-containing film (for example, an organic tin oxide precursor) can be 0.01 to 10 cmm, and the gas flow rate (CO2, CO, Ar, N2) can be 100 to 10,000 sccm. The plasma power can use high-frequency plasma (for example, 13.56 MHz, 27.1 MHz, or higher frequencies) of 200 to 1,000 W per 300 mm wafer station. The evaporation thickness is preferably 100 to 2,000 angstroms.

[0454] The exposure light is high-energy radiation having a wavelength of 300 nm or less, and specifically, for example, excimer lasers of 248 nm, 193 nm, and 157 nm, soft X-rays of 3 to 20 nm, electron beams, X-rays, and the like.

[0455] The patterning method of the resist upper layer film is preferably optical lithography with a wavelength of 5 nm to 300 nm, direct writing using an electron beam, nanoimprinting, or a combination thereof.

[0456] Furthermore, the development method of the above-mentioned pattern forming method may be preferably alkali development or organic solvent development.

[0457] The obtained resist pattern is then used as a mask for etching. The etching of the silicon-containing resist intermediate film and the inorganic hard mask of the three-layer resist process is performed using a fluorine-based gas with the upper resist pattern as a mask. In this way, a silicon-containing resist intermediate film pattern and an inorganic hard mask pattern can be formed.

[0458] Next, the resist underlayer film is etched using the obtained silicon-containing resist intermediate film pattern and the inorganic hard mask pattern as masks. The etching of the resist underlayer film is preferably performed using an etching gas mainly containing oxygen-based gas.

[0459] The etching of the processed object can be carried out according to the usual method. For example, if the processed object is SiO2, SiN, or a silicon dioxide-based low dielectric constant insulating film, etching can be carried out mainly using a fluorine-based gas. When the substrate is processed using fluorine-based gas etching, the silicon-containing resist intermediate film pattern of the three-layer resist treatment will be peeled off while the substrate is being processed.

[0460] The resist underlayer film obtained using the resist underlayer film-forming composition of the present invention is characterized by being excellent in etching resistance when etching such a workpiece.

[0461] Furthermore, the object to be processed (substrate to be processed) is not particularly limited, and substrates such as Si, α-Si, p-Si, SiO2, SiN, SiON, W, TiN, Al, and a film on which a processed layer is formed can be used. The processed layer can be various Low-k films such as Si, SiO2, SiON, SiN, p-Si, α-Si, W, W-Si, Al, Cu, Al-Si, and barrier films thereof, and can generally be formed to a thickness of 50 to 10,000 nm, particularly 100 to 5,000 nm. Furthermore, when forming the processed layer, the substrate and the processed layer can be made of different materials.

[0462] The pattern forming method using the resist underlayer film forming composition of the present invention preferably uses a substrate to be processed having a structure or height difference of 30nm or more. As mentioned above, the resist underlayer film forming composition of the present invention has excellent filling and / or flattening properties, so even if the substrate to be processed has a structure or height difference (concave and convex) of 30nm or more, a flat hardened film can still be formed. The height of the structure or height difference of the above-mentioned processed substrate is preferably 30nm or more, more preferably 50nm or more, and more preferably 100nm or more. In the method of processing a substrate with a height difference of a pattern having the above-mentioned height, by forming a film of the resist underlayer film forming composition of the present invention and filling and / or flattening, the film thickness of the resist intermediate film and the resist upper film formed later can be made uniform, so the exposure depth tolerance (DOF) during optical lithography is easy to ensure, which is very ideal.

[0463] <Resist Underlayer Film Formation Method>

[0464] The present invention provides a method for forming an anti-etching underlayer film, which is a method for forming an anti-etching underlayer film that acts as an organic flat film used in the manufacturing step of a semiconductor device. The method is characterized in that a coating film is obtained by spin-coating the composition for forming an anti-etching underlayer film of the present invention on a processed substrate, and the coating film is heat-treated at a temperature in the range of 450°C to 800°C for 10 to 600 seconds to harden it and form a anti-etching underlayer film.

[0465] In addition, a method for forming an anti-etching underlayer film is provided, which is a method for forming an anti-etching underlayer film that acts as an organic flat film used in the manufacturing step of a semiconductor device, and is characterized in that: the composition for forming an anti-etching underlayer film of the present invention is spin-coated on a processed substrate to obtain a coating film, and the coating film is heat-treated in a gas environment with an oxygen concentration of not less than 1% and not more than 21% to harden it, thereby forming a anti-etching underlayer film.

[0466] Or a method for forming an anti-etching underlayer film is provided, which is a method for forming an anti-etching underlayer film that acts as an organic flat film used in the manufacturing step of a semiconductor device, and is characterized in that: the composition for forming an anti-etching underlayer film of the present invention is spin-coated on a processed substrate to obtain a coating film, and the coating film is heat-treated in a gas environment with an oxygen concentration of less than 1% to harden it and form a anti-etching underlayer film.

[0467] The resist lower film forming method of the present invention is to apply the resist lower film material to the processed substrate by spin coating or the like. By using the spin coating method or the like, good filling characteristics can be obtained. After spin coating, the organic solvent is evaporated, and heat treatment (baking) is performed to prevent mixing with the resist upper film and the resist intermediate film and to promote the crosslinking reaction. Baking is preferably performed in the range of 100°C to 800°C, more preferably in the range of 300°C to 800°C, and more preferably in the range of 450°C to 800°C. The baking time is preferably 10 seconds to 600 seconds, and more preferably in the range of 10 to 300 seconds. By appropriately adjusting the baking temperature and time within the above range, flattening and / or filling characteristics suitable for the application can be obtained, and hardening characteristics such as dry etching resistance and heat resistance can be obtained. By baking in the temperature range of 450°C to 800°C, particularly excellent dry etching resistance can be obtained. When the baking temperature is 100°C or higher, curing is fully performed and mixing with the resist upper film or the resist intermediate film can be suppressed. When the baking temperature is 800°C or lower, thermal decomposition of the base resin can be suppressed, the film thickness does not decrease, and the film surface becomes uniform.

[0468] The gas environment during heat treatment can be selected according to the needs, such as oxygen-containing environment in air (oxygen concentration 1% to 21%) or non-oxygen environment in nitrogen. For example, when the substrate to be processed is easily oxidized by air, heat treatment in a gas environment with an oxygen concentration of less than 1% and forming a hardened film can inhibit damage to the substrate.

[0469] In the resist underlayer film forming method using the resist underlayer film forming composition of the present invention, it is preferred to use a processed substrate having a structure or height difference of 30nm or more. As mentioned above, the resist underlayer film forming composition of the present invention has excellent filling and / or flattening properties, and can still form a flat hardened film even if the processed substrate has a structure or height difference (concave and convex) of 30nm or more. The height of the structure or height difference possessed by the above-mentioned processed substrate is preferably 30nm or more, more preferably 50nm or more, and more preferably 100nm or more. In the method of processing a substrate with a height difference having a pattern of the above-mentioned height, by forming a film of the resist underlayer film forming composition of the present invention and filling and / or flattening, the film thickness of the resist intermediate film and the resist upper film formed thereafter can be uniform, so the exposure depth tolerance (DOF) during optical lithography is easy to ensure, which is very ideal.

[0470] [Example]

[0471] The following synthesis examples, comparative synthesis examples, embodiments, and comparative examples are provided to more specifically describe the present invention, but the present invention is not limited thereto. In addition, the molecular weight and the dispersity are obtained by determining the weight average molecular weight (Mw) and the number average molecular weight (Mn) in terms of polystyrene measured by gel permeation chromatography (GPC) using tetrahydrofuran as an eluent, and determining the dispersity (Mw / Mn).

[0472] Synthesis Example (A) Synthesis of polymer

[0473] The following compound group b: (b1) to (b6) was used for the synthesis of polymers (A1) to (A7).

[0474] [Chemistry 68]

[0475]

[0476] [Synthesis Example 1] Synthesis of polymer (A1)

[0477] [Chemistry 69]

[0478]

[0479] Under a nitrogen atmosphere, 31.2 g of compound (b1) and 300 g of 1,2-dichloroethane were mixed and uniformly dispersed at an internal temperature of 60°C. 41.6 g of methanesulfonic acid was added dropwise to the obtained mixture over a period of 1 hour, and the mixture was heated and stirred at an internal temperature of 70°C for 6 hours. The mixture was cooled to room temperature, and then 400 g of 1,2-dichloroethane was added, and the insoluble components were removed by filtration. The recovered filtrate was washed 6 times with 200 g of pure water, and the organic layer was dried under reduced pressure. 150 g of THF was added to the residue to make a uniform solution, and then crystallized in 500 g of methanol. The precipitated crystals were separated by filtration, washed with 300 g of methanol and 300 g of diisopropyl ether in that order, and the crystals were recovered. The recovered crystals were vacuum dried at 70°C to obtain polymer (A1).

[0480] The weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, and the following results were obtained.

[0481] (A1): Mw=2,710, Mw / Mn=1.86

[0482] [Synthesis Example 2] Synthesis of polymer (A2)

[0483] [Chemistry 70]

[0484]

[0485] Under a nitrogen environment, 45.6 g of compound (b2) and 300 g of 1,2-dichloroethane were mixed and uniformly dispersed at an internal temperature of 60°C. 41.6 g of methanesulfonic acid was added dropwise to the obtained mixture over a period of 1 hour, and the mixture was heated and stirred at an internal temperature of 70°C for 6 hours. After the mixture was cooled to room temperature, 400 g of 1,2-dichloroethane was added, and then the insoluble components were removed by filtration. The recovered filtrate was washed 6 times with 200 g of pure water, and the organic layer was dried under reduced pressure. 150 g of THF was added to the residue to make a uniform solution, and then crystallized in 500 g of methanol. The precipitated crystals were separated by filtration, washed with 300 g of methanol and 300 g of diisopropyl ether in that order, and the crystals were recovered. The recovered crystals were vacuum dried at 70°C to obtain polymer (A2).

[0486] The weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, and the following results were obtained.

[0487] (A2): Mw=2,030, Mw / Mn=1.56

[0488] [Synthesis Example 3] Synthesis of polymer (A3)

[0489] [Chemistry 71]

[0490]

[0491] Under a nitrogen environment, 60.0 g of compound (b3) and 300 g of 1,2-dichloroethane were mixed and uniformly dispersed at an internal temperature of 60°C. 55.4 g of methanesulfonic acid was added dropwise to the obtained mixture over a period of 1 hour, and the mixture was heated and stirred at an internal temperature of 70°C for 6 hours. After the mixture was cooled to room temperature, 400 g of 1,2-dichloroethane was added, and the insoluble components were removed by filtration. The recovered filtrate was washed 6 times with 200 g of pure water, and the organic layer was dried under reduced pressure. After adding 150 g of THF to the residue to make a uniform solution, it was crystallized in 500 g of methanol. The precipitated crystals were separated by filtration, washed with 300 g of methanol and 300 g of diisopropyl ether in that order, and the crystals were recovered. The recovered crystals were vacuum dried at 70°C to obtain polymer (A3).

[0492] The weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, and the following results were obtained.

[0493] (A3): Mw=560, Mw / Mn=2.43

[0494] [Synthesis Example 4] Synthesis of polymer (A4)

[0495] [Chemistry 72]

[0496]

[0497] Under a nitrogen atmosphere, 30.0 g of compound (b3), 15.6 g of compound (b1) and 230 g of 1,2-dichloroethane were mixed and uniformly dispersed at an internal temperature of 60°C. 55.4 g of methanesulfonic acid was added dropwise to the obtained mixture over a period of 1 hour, and the mixture was heated and stirred at an internal temperature of 70°C for 6 hours. After the mixture was cooled to room temperature, 200 g of 1,2-dichloroethane was added, and the insoluble components were removed by filtration. The recovered filtrate was washed 6 times with 100 g of pure water, and the organic layer was dried under reduced pressure. 120 g of THF was added to the residue to make a uniform solution, and then crystallized in 600 g of methanol. The precipitated crystals were separated by filtration, washed with 300 g of methanol and 300 g of diisopropyl ether in that order, and the crystals were recovered. The recovered crystals were vacuum dried at 70°C to obtain polymer (A4).

[0498] The weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, and the following results were obtained.

[0499] (A4): Mw=680, Mw / Mn=2.27

[0500] [Synthesis Example 5] Synthesis of polymer (A5)

[0501] [Chemistry 73]

[0502]

[0503] Under a nitrogen environment, 30.0 g of compound (b3), 22.8 g of compound (b4) and 260 g of 1,2-dichloroethane were mixed and uniformly dispersed at an internal temperature of 60°C. 55.4 g of methanesulfonic acid was added dropwise to the obtained mixture over a period of 1 hour, and the mixture was heated and stirred at an internal temperature of 70°C for 6 hours. After the mixture was cooled to room temperature, 200 g of 1,2-dichloroethane was added, and the insoluble components were removed by filtration. The recovered filtrate was washed 6 times with 100 g of pure water, and the organic layer was dried under reduced pressure. 120 g of THF was added to the residue to make a uniform solution, which was then crystallized in 600 g of methanol. The precipitated crystals were separated by filtration, washed with 300 g of methanol and 300 g of diisopropyl ether in that order, and the crystals were recovered. The recovered crystals were vacuum dried at 70°C to obtain polymer (A5).

[0504] The weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, and the following results were obtained.

[0505] (A5): Mw=720, Mw / Mn=2.13

[0506] [Synthesis Example 6] Synthesis of polymer (A6)

[0507] [Chemistry 74]

[0508]

[0509] Under a nitrogen atmosphere, 60.0 g of compound (b3), 4.6 g of compound (b5) and 325 g of 1,2-dichloroethane were mixed and uniformly dispersed at an internal temperature of 60°C. 55.4 g of methanesulfonic acid was added dropwise to the obtained mixture over a period of 1 hour, and the mixture was heated and stirred at an internal temperature of 70°C for 6 hours. After the mixture was cooled to room temperature, 200 g of 1,2-dichloroethane was added, and the insoluble components were removed by filtration. The recovered filtrate was washed 6 times with 100 g of pure water, and the organic layer was dried under reduced pressure. 200 g of THF was added to the residue to make a uniform solution, and then crystallized in 600 g of methanol. The precipitated crystals were separated by filtration, washed with 300 g of methanol and 300 g of diisopropyl ether in that order, and the crystals were recovered. The recovered crystals were vacuum dried at 70°C to obtain polymer (A6).

[0510] The weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, and the following results were obtained.

[0511] (A6): Mw=700, Mw / Mn=1.43

[0512] [Synthesis Example 7] Synthesis of polymer (A7)

[0513] [Chemistry 75]

[0514]

[0515] Under a nitrogen environment, 30.0 g of anthracene, 46.3 g of compound (c6) and 300 g of 1,2-dichloroethane were mixed and uniformly dispersed at an internal temperature of 60°C. Then, 55.0 g of methanesulfonic acid was added dropwise over 1 hour, and the mixture was heated and stirred at an internal temperature of 70°C for 24 hours. After the mixture was cooled to room temperature, 400 g of 1,2-dichloroethane was added, and the insoluble components were removed by filtration. The recovered filtrate was washed 6 times with 200 g of ultrapure water, and the organic layer was dried under reduced pressure. After adding 150 g of THF to the residue to make a uniform solution, it was crystallized in 500 g of diisopropyl ether. The precipitated crystals were separated by filtration, washed twice with 300 g of diisopropyl ether, and the crystals were recovered. The recovered crystals were vacuum dried at 70°C to obtain polymer (A7).

[0516] The weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, and the following results were obtained.

[0517] (A7): Mw=942, Mw / Mn=2.73

[0518] Comparative Synthesis Examples Synthesis of Comparative Polymers and Comparative Compounds

[0519] The synthesis of the comparative example polymers (R2), (R3), (R5), (R7), (R9) and (R11) used the following compound group c: (c1) to (c5) and the above compound group b: (b2).

[0520] [Chemistry 76]

[0521]

[0522] [Comparative Synthesis Example 1] Synthesis of Comparative Polymer (R1)

[0523] [Chemistry 77]

[0524]

[0525] Under a nitrogen atmosphere, 160.2 g of 1,5-dihydroxynaphthalene, 64.9 g of a 37% formaldehyde solution, and 300 g of PGME (propylene glycol monomethyl ether) were mixed and homogenized at an internal temperature of 100°C. Then, a mixture of 8.0 g of p-toluenesulfonic acid monohydrate and 8.0 g of PGME, which had been mixed and homogenized in advance, was slowly added dropwise, and the mixture was reacted at an internal temperature of 80°C for 8 hours. After the reaction was completed, the mixture was cooled to room temperature, 2,000 ml of methyl isobutyl ketone (MIBK) was added, and the mixture was washed 6 times with 500 ml of ultrapure water, and the organic layer was dried under reduced pressure. 300 g of THF was added to the residue to make a uniform solution, and then crystallized in 2,000 g of hexane. The precipitated crystals were separated by filtration, washed twice with 500 g of hexane, and the crystals were recovered. The recovered crystals were vacuum dried at 70°C to obtain a polymer (R1).

[0526] The weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, and the following results were obtained.

[0527] (R1): Mw=4,000, Mw / Mn=3.0

[0528] [Comparative Synthesis Example 2] Synthesis of Comparative Example Polymer (R2)

[0529] [Chemistry 78]

[0530]

[0531] Under a nitrogen environment, 90.1 g of compound (c1), 9.7 g of a 37% formaldehyde solution, and 270 g of 2-methoxy-1-propanol were mixed to form a uniform solution at a liquid temperature of 80°C. Next, 18 g of a 20% p-toluenesulfonic acid solution in 2-methoxy-1-propanol was slowly added, and the mixture was stirred at a liquid temperature of 110°C for 8 hours. After the mixture was cooled to room temperature, 600 g of methyl isobutyl ketone was added, and the organic layer was washed five times with 200 g of ultrapure water, and then dried under reduced pressure. 320 g of THF was added to the residue, and the polymer was reprecipitated with 1,350 g of hexane. The precipitated polymer was separated by filtration and dried under reduced pressure to obtain a polymer (R2).

[0532] The weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, and the following results were obtained.

[0533] (R2): Mw=3,460, Mw / Mn=4.60

[0534] [Comparative Synthesis Example 3] Synthesis of Comparative Example Polymer (R3)

[0535] [Chemistry 79]

[0536]

[0537] The polymer reported in [Synthesis Example 1] of Japanese Patent Application Laid-Open No. 2021-138851 was synthesized. 54.5 g of fluorenol (c2) and 200 g of 1,2-dichloroethane were mixed and the temperature was raised to 50°C. 20.3 g of methanesulfonic acid was slowly added dropwise and heated and stirred at 70°C for 6 hours. After cooling to room temperature, 650 g of toluene was added, and the mixture was washed 6 times with 100 g of ultrapure water, and the organic layer was dried under reduced pressure. 200 g of THF was added to the residue to make a uniform solution, which was then crystallized in 600 g of methanol. The precipitated crystals were separated by filtration, washed twice with 200 g of methanol, and the crystals were recovered. The recovered crystals were vacuum dried at 70°C to obtain a polymer (R3).

[0538] The weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, and the following results were obtained.

[0539] (R3): Mw=2,700, Mw / Mn=1.39

[0540] [Comparative Synthesis Example 4] Synthesis of Comparative Example Compound (R4)

[0541] [Chemistry 80]

[0542]

[0543] Under nitrogen atmosphere, 20.0 g of di-1-naphthylmethanol and 240 ml of dichloroethane were mixed, homogenized at room temperature, and then 11.6 g of triethylsilane and 2.9 g of methanesulfonic acid were added. After stirring for 5 minutes to form a uniform solution, the mixture was reacted in an oil bath at 60°C for 3 hours. The mixture was cooled to room temperature, and 100 ml of ultrapure water was slowly added to quench the reaction. The mixture was transferred to a separatory funnel, the organic phase of the lower layer was recovered, and after washing with ultrapure water 5 times, the organic layer was dried under reduced pressure to recover compound (R4).

[0544] The weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, and the following results were obtained.

[0545] (R4): Mw=280, Mw / Mn=1.01

[0546] [Comparative Synthesis Example 5] Synthesis of Comparative Example Polymer (R5)

[0547] [Chemistry 81]

[0548]

[0549] Under a nitrogen environment, 60.0 g of compound (b2) and 300 g of 1,2-dichloroethane were mixed, and after being uniformly dispersed at an internal temperature of 60°C, 74.5 g of methanesulfonic acid was added dropwise over 1 hour, and heated and stirred at an internal temperature of 70°C for 6 hours. After the mixture was cooled to room temperature, 400 g of 1,2-dichloroethane was added, and the insoluble components were removed by filtration. The recovered filtrate was washed 6 times with 200 g of pure water, and the organic layer was dried under reduced pressure. 200 g of THF was added to the residue to make a uniform solution, and then crystallized in 600 g of methanol. The precipitated crystals were separated by filtration, washed twice with 400 g of methanol, and the crystals were recovered. The recovered crystals were vacuum dried at 70°C to obtain polymer (R5).

[0550] The weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, and the following results were obtained.

[0551] (R5): Mw=3,150, Mw / Mn=1.43

[0552] [Comparative Synthesis Example 6] Synthesis of Comparative Example Polymer (R6)

[0553] [Chemistry 82]

[0554]

[0555] Under nitrogen environment, 15.6g of 2-phenylphenol, 19.1g of 9-anthracene methanol, 12.3g of divinylbenzene, 30g of cyclopentyl methyl ether (CPME) and 110g of diethylene glycol dimethyl ether were mixed, stirred at room temperature and uniformly dispersed. Then, 1.14g of trifluorosulfonic acid was slowly added, stirred for another 5 minutes, and after a uniform solution was made, the reaction was carried out for 4 hours in an oil bath at 140°C while removing the generated water from the reaction system. The reactant was cooled to room temperature, diluted with 250g of CPME and transferred to a separatory funnel. After washing with ultrapure water 4 times, the organic layer was dried under reduced pressure. 120g of CPME was added to the residue, and the polymer was crystallized with 500g of hexane. The crystals of crystallization were separated by filtration, washed twice with 200g of hexane, and the crystals were recovered. The recovered crystals were vacuum dried at 70°C to obtain polymer (R6).

[0556] The weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, and the following results were obtained.

[0557] (R6): Mw=1,960, Mw / Mn=1.57

[0558] [Comparative Synthesis Example 7] Synthesis of Comparative Example Polymer (R7)

[0559] [Chemistry 83]

[0560]

[0561] Under a nitrogen atmosphere, 38.0 g of compound (c3), 17.0 g of 1,4-bis(methoxymethyl)benzene, 0.5 g of diethyl sulfate and 82 g of propylene glycol monomethyl ether acetate (PGMEA) were mixed and stirred at 100°C for 2 to 15 hours to perform a polymerization reaction. After the reactants were slowly cooled to room temperature, the reactants were added to 40 g of ultrapure water and 400 g of methanol and stirred vigorously and then allowed to stand. The supernatant was removed, and the precipitate was dissolved in 80 g of propylene glycol monomethyl ether acetate (PGMEA), and then stirred vigorously with 320 g of methanol and 320 g of ultrapure water and allowed to stand (1st step). At this time, the supernatant obtained was removed again, and the precipitate was dissolved in 80 g of propylene glycol monomethyl ether acetate (PGMEA) (2nd step). The 1st and 2nd steps were regarded as 1st purification step, and this purification step was performed 3 times in total. After the purification, the polymer was dissolved in 80 g of propylene glycol monomethyl ether acetate (PGMEA), and then the remaining methanol and ultrapure water were removed under reduced pressure to obtain a polymer (R7).

[0562] The weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, and the following results were obtained.

[0563] (R7): Mw=3,500, Mw / Mn=1.52

[0564] [Comparative Synthesis Example 8] Synthesis of Comparative Example Polymer (R8)

[0565] [Chemistry 84]

[0566]

[0567] Under a nitrogen atmosphere, 28.3 g of pyrene, 28.8 g of 1-naphthol, 12.1 g of formaldehyde, 0.57 g of p-toluenesulfonic acid monohydrate and 1,000 g of propylene glycol monomethyl ether acetate (PGMEA) were mixed and stirred at room temperature for 17.5 hours to perform a polymerization reaction. After the reactants were slowly cooled at room temperature, the reactants were added to 40 g of ultrapure water and 400 g of methanol and stirred vigorously and then allowed to stand. After the supernatant was removed and the precipitate was dissolved in 80 g of propylene glycol monomethyl ether acetate (PGMEA), 320 g of methanol was used to stir vigorously and then allowed to stand (1st step). At this time, the supernatant obtained was removed again, and the precipitate was dissolved in 80 g of propylene glycol monomethyl ether acetate (PGMEA) (2nd step). The aforementioned 1st and 2nd steps were regarded as 1st purification step, and this purification step was performed 3 times in total. After the purification, the polymer was dissolved in 80 g of propylene glycol monomethyl ether acetate (PGMEA), and then the remaining methanol and ultrapure water were removed under reduced pressure to obtain a polymer (R8).

[0568] The weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, and the following results were obtained.

[0569] (R8): Mw=4,000, Mw / Mn=1.75

[0570] [Comparative Synthesis Example 9] Synthesis of Comparative Example Polymer (R9)

[0571] [Chemistry 85]

[0572]

[0573] Under a nitrogen atmosphere, 5.0 g of compound (c4), 2.1 g of 1,4-bis(methoxymethyl)benzene, 0.1 g of diethyl sulfate and 15 g of propylene glycol monomethyl ether acetate (PGMEA) were mixed and stirred at 100° C. for 24 hours to perform a polymerization reaction. The reactant was precipitated in methanol to remove monomers and low molecular weight products, thereby obtaining a polymer (R9).

[0574] The weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, and the following results were obtained.

[0575] (R9): Mw=2,500, Mw / Mn=2.1

[0576] [Comparative Synthesis Example 10] Synthesis of Comparative Example Polymer (R10)

[0577] [Chemistry 86]

[0578]

[0579] In a nitrogen environment, 3.5 g of indole, 6.0 g of pyrene, 1.8 g of p-formaldehyde, 0.57 g of p-toluenesulfonic acid·monohydrate and 100 g of propylene glycol monomethyl ether acetate (PGMEA) were mixed and stirred at 90°C for 12 hours to perform a polymerization reaction. After the reactants were slowly cooled at room temperature, the reactants were added to 300 g of pure water and 300 g of methanol and stirred vigorously and then allowed to stand. The supernatant was removed, and the precipitate was dissolved in 100 g of propylene glycol monomethyl ether acetate (PGMEA), and then stirred vigorously with 300 g of methanol and 300 g of ultrapure water and allowed to stand (1st step). At this time, the supernatant obtained was removed again, and the precipitate was dissolved in 80 g of propylene glycol monomethyl ether acetate (PGMEA) (2nd step). The aforementioned 1st and 2nd steps were used as 1st purification step, and this purification step was carried out 3 times in total. After the purification, the polymer was dissolved in 80 g of propylene glycol monomethyl ether acetate (PGMEA), and then the remaining methanol and ultrapure water were removed under reduced pressure to obtain a polymer (R10).

[0580] The weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, and the following results were obtained.

[0581] (R10): Mw=2,800, Mw / Mn=1.51

[0582] [Comparative Synthesis Example 11] Synthesis of Comparative Example Polymer (R11)

[0583] [Chemistry 87]

[0584]

[0585] Under a nitrogen environment, 30.0 g of anthracene, 22.2 g of compound (c5) and 300 g of 1,2-dichloroethane were mixed and uniformly dispersed at an internal temperature of 60°C. Then, 55.0 g of methanesulfonic acid was added dropwise over 1 hour, and heated and stirred at an internal temperature of 70°C for 24 hours. After the mixture was cooled to room temperature, 400 g of 1,2-dichloroethane was added, and the insoluble components were removed by filtration. The recovered filtrate was washed 6 times with 200 g of ultrapure water, and the organic layer was dried under reduced pressure. 150 g of THF was added to the residue to make a uniform solution, and then crystallized in 500 g of diisopropyl ether. The precipitated crystals were separated by filtration, washed twice with 300 g of diisopropyl ether, and the crystals were recovered. The recovered crystals were vacuum dried at 70°C to obtain a polymer (R11).

[0586] The weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, and the following results were obtained.

[0587] (R11): Mw=2,480, Mw / Mn=1.93

[0588] [Example 1 and Comparative Example 1: Solubility Evaluation]

[0589] The solubility of the (A) polymers (A1) to (A7) and the comparative example polymers (R1) to (R11) synthesized above was confirmed.

[0590] The solvent used was propylene glycol monomethyl ether acetate (PGMEA) and cyclohexanone (CyHO), and the solubility was evaluated under three conditions: 70 / 30, 50 / 50, and CyHO alone. The solution was evaluated as "soluble" when it was completely dissolved to form a uniform solution, and "insoluble" when it was not completely dissolved and there was insoluble matter.

[0591] The results are shown in Table 1 below.

[0592] [Table 1]

[0593]

[0594] Examples 1-1 to 1-6 using the polymer used in the resist underlayer film forming composition of the present invention show good solubility in a mixed solvent of PGMEA / CyHO=50 / 50 and CyHO. Comparing Examples 1-1 to 1-3, the solubility of the polymer of the present invention tends to deteriorate as the structure of the condensed aromatic ring increases, but polymers (A1) to (A6) containing polymers (A2) and (A3) can be dissolved in a mixed solvent of PGMEA / CyHO=50 / 50 and a solvent of CyHO. Basically, the solubility of the resin is better in CyHO, but from the viewpoint of film-forming properties, it is better to contain more PGMEA.

[0595] Among the polymers used in the resist underlayer film forming composition of the present invention, only Example 1-7 is insoluble in the PGMEA / CyHO system. This polymer is a resin with a similar structure to the polymer (A3) in that the aromatic group represented by Ar in the above general formula (1) is anthracene, but is synthesized by the alternative method 2 having a different synthesis formula. The molecular weight of the synthesis by the alternative method 2 is difficult to control, presumably because the molecular weight is larger than that of the polymer (A3).

[0596] On the other hand, Comparative Example 1-5 using the comparative example polymer (R5) having a higher molecular weight than the polymer used in the resist underlayer film forming composition of the present invention had unsatisfactory solubility in CyHO. It is understood that molecular weight control is important for excellent solvent solubility.

[0597] Furthermore, the comparative polymers (R11) of comparative examples 1-11 using a block copolymer having a unit containing a substituted aromatic group as a repeating unit, which is different from the polymer used in the resist underlayer film forming composition of the present invention, all had unsatisfactory solubility in the experimental solvents.

[0598] The polymers (A4) and (A5) used in the resist underlayer film forming composition of the present invention are random polymers and are soluble in a mixed solvent of PGMEA / CyHO=70 / 30, a mixed solvent of PGMEA / CyHO=50 / 50, and CyHO. Therefore, it can be seen that the polymer used in the resist underlayer film forming composition of the present invention has excellent solvent solubility.

[0599] In Examples 1-4 to 1-6 using polymers (A4) and (A5) having copolymers of two repeating units and a polymer (A6) end-capped with 2,3-naphthol, compared with Example 1-3 using polymer (A3), improved solubility in a mixed solvent of PGMEA / CyHO=70 / 30 was obtained.

[0600] Preparation of resist underlayer film forming composition

[0601] Each resist underlayer film-forming composition was prepared by the following procedure using the polymers (A1) to (A7) having good solubility evaluation and the comparative example polymers (R1) to (R4) and (R6) to (R10).

[0602] [Preparation of Resist Underlayer Film Forming Composition UDL-1]

[0603] The polymer (A1) was dissolved in a mixed solvent of propylene glycol monomethyl ether acetate (PGMEA) and cyclohexanone (CyHO) containing 0.5% by mass of a surfactant FC-4430 (manufactured by Sumitomo 3M Co., Ltd.) in the proportions shown in Table 3, and filtered with a 0.02 μm filter membrane to prepare a composition for forming a resist underlayer film (UDL-1).

[0604] [Preparation of Resist Underlayer Film Forming Compositions (UDL-2 to 12) and Resist Underlayer Film Forming Compositions for Comparative Examples (Comparative Examples UDL-1 to 9)]

[0605] The types and contents of the components are shown in Table 3. The same operations as those for the resist underlayer film forming composition UDL-1 were performed to prepare the resist underlayer film forming compositions. In Table 3, "-" represents that the corresponding component is not used. The blending resin is a resin represented by any of the following formulas (C1) to (C3), the crosslinking agent is a compound represented by the following formula (D1), the acid generator (TAG) is a compound represented by the following formula (G1), and the fluidity promoter is a compound represented by the following formula (E1).

[0606] [Blended resin]

[0607] The blending resins (C1) to (C3) used in the resist underlayer film forming compositions UDL-8 to UDL-10 are as follows.

[0608] [Chemistry 88]

[0609]

[0610] [Crosslinking agent]

[0611] The cross-linking agent (D1) used in the resist underlayer film forming composition UDL-11 is shown below.

[0612] [Chemistry 89]

[0613]

[0614] [Acid generator]

[0615] The thermal acid generator (G1) used in the resist underlayer film forming composition UDL-11 is shown below.

[0616] [Chemistry 90]

[0617]

[0618] [Flowability enhancer]

[0619] The fluidity enhancer (E1) used in the resist underlayer film forming composition UDL-12 is shown below.

[0620] [Table 2]

[0621]

[0622] [Table 3]

[0623]

[0624] [Example 2 and Comparative Example 2: Evaluation of Solvent Resistance and Film Thickness Uniformity during High-Temperature Treatment in a Nitrogen Atmosphere]

[0625] The above-mentioned resist underlayer film forming compositions (UDL-1 to 12 and comparative examples UDL-1 to 9) were coated on a silicon substrate, fired at 350°C for 60 seconds, and then fired at 550°C for 90 seconds in a nitrogen environment with an oxygen concentration of less than 0.2%. The film thickness from the center to the periphery of the substrate was measured, and the average film thickness (a [nm]) was calculated. Then, PGMEA solvent was dispensed on it, left for 30 seconds and spun dry, and baked at 100°C for 60 seconds to evaporate PGMEA, and the film thickness (b [nm]) was measured. The difference in film thickness before and after PGMEA treatment was calculated (residual film rate: (b / a) × 100).

[0626] In addition, for each film obtained by firing at 550°C for 90 seconds in a nitrogen environment with an oxygen concentration of less than 0.2%, the film thickness from the center to the periphery of the substrate was measured, and when the difference between the maximum film thickness and the minimum film thickness relative to the average film thickness (a) was less than 4%, it was rated as "very good", when it was 4-8%, it was rated as "good", and when it was more than 8%, it was rated as "poor".

[0627] The results are shown in Table 4 below.

[0628] [Table 4]

[0629]

[0630]

[0631] As shown in Table 4, in Examples 2-1 to 2-12 using the resist underlayer film forming composition (UDL-1 to 12) of the present invention, the residual film rate ((a / b)×100) after PGMEA rinsing treatment was 99% or more, indicating that a crosslinking reaction occurred and sufficient solvent resistance was exhibited.

[0632] In addition, in Examples 2-1 to 2-12 using the resist underlayer film forming composition (UDL-1 to 12) of the present invention, the difference between the maximum film thickness and the minimum film thickness of the film after firing at 550°C in a nitrogen environment is less than 8% relative to the average film thickness (a), indicating that the film thickness uniformity is good. In addition, it can be confirmed that Examples 2-8 to 2-11 containing (C) blending resin and (D) crosslinking agent have improved film thickness uniformity compared to Example 2-3 not containing them. On the other hand, Comparative Example 2-4 using a resin with a small molecular weight has a large amount of sublimates during high-temperature treatment, and the film thickness becomes extremely thin compared to the others, and the film thickness uniformity is also deteriorated. Comparative Example 2-5 may have poor heat resistance due to the use of a polymer (R6) containing a repeating unit having a hydroxyl group, and it is speculated that the thermal decomposition is severe and the film thickness uniformity is deteriorated.

[0633] [Example 3 and Comparative Example 3: Evaluation of Filling Characteristics and Flatness]

[0634] Evaluation of embedding property: The above-mentioned resist underlayer film forming composition (UDL-1 to 11 and comparative examples UDL-1 to 9) was coated on a SiO2 wafer substrate having a dense line & space pattern (line width 60nm, line depth 100nm, distance between the centers of two adjacent lines (120nm), and fired at 350°C for 60 seconds using a hot plate, and then fired at 550°C for 90 seconds in a nitrogen environment with an oxygen concentration of 0.2% or less to form a resist underlayer film with a film thickness of 100nm. The substrate used was as follows Figure 2 The base substrate 9 (SiO2 wafer substrate) having a dense line & space pattern is shown in (Q) (bird's eye view) and (R) (cross-sectional view).

[0635] The cross-sectional shape of each wafer substrate obtained was observed using an electron microscope (S-4700) manufactured by Hitachi, Ltd. to confirm whether there were pores (voids) inside the resist underlayer film between the filling lines. The results are shown in Table 5. When a resist underlayer film-forming composition with poor filling characteristics was used, pores occurred inside the resist underlayer film between the filling lines in this evaluation. When a resist underlayer film-forming composition with good filling characteristics was used, pores occurred inside the resist underlayer film between the filling lines in this evaluation. Figure 2 As shown in (S), the resist underlayer film 10 without voids is filled inside the resist underlayer film filling the spaces between the lines of the base substrate 9 having a dense line & space pattern.

[0636] Flatness evaluation: For Figure 3 The dense line & space pattern of the base substrate 11 (SiO2 wafer substrate) shown in (T) is observed using a scanning electron microscope (SEM) as shown in Figure 3The cross-sectional shape of each wafer substrate obtained by the above-mentioned filling characteristic evaluation was observed, and the height difference Delta 12 of the filling film 12 in the line pattern dense part and the non-line pattern forming part was observed using an electron microscope (S-4700) manufactured by Hitachi, Ltd. In this evaluation, the larger the height difference, the better the flattening characteristic. The results are shown in Table 5.

[0637] [Table 5]

[0638]

[0639] As shown in Table 5, Examples 3-1 to 3-12 using the resist underlayer film forming composition (UDL-1 to 12) of the present invention can fill the dense line & space pattern without generating voids, and it is confirmed that they have good filling characteristics.

[0640] Furthermore, when Example 3-1 is compared with Example 3-12, Example 3-12 has a better result in flatness. This is considered to be because the thermal fluidity is improved by adding the fluidity promoter (E1).

[0641] On the other hand, Comparative Example 3-4 using a low molecular weight COPNA resin and Comparative Example 3-5 using a polymer (R6) containing a repeating unit having a hydroxyl group generated voids. These both had significantly insufficient heat resistance, and voids were presumably generated by decomposition products.

[0642] [Example 4 and Comparative Example 4: Etching Resistance Evaluation]

[0643] The resist underlayer film-forming compositions (UDL-1 to 12 and comparative examples UDL-1 to 9) were coated on a silicon substrate, respectively, and the coated films were heated at 350°C for 60 seconds using a hot plate to form resist underlayer films (350°C fired films), and the film thickness a was measured. Then, each etching using CF4 gas was performed under the following conditions using an etching apparatus Telius manufactured by Tokyo Electron, and the film thickness b was measured. From the film thickness etched during a specified time using each gas (film thickness a - film thickness b), the film thickness etched in 1 minute was calculated and defined as the etching rate A (nm / min).

[0644] Separately from the above, the above-mentioned resist underlayer film forming compositions (UDL-1 to 12 and comparative examples UDL-1 to 9) were coated on silicon substrates, respectively, and the coated films were heated at 350°C for 60 seconds using a hot plate, and then fired at 450°C or 550°C for 90 seconds in a nitrogen environment with an oxygen concentration of less than 0.2% to form a resist underlayer film (high-temperature fired film), and the film thickness c was measured. Then, each etching using CF4 gas was carried out under the following conditions using an etching device Telius manufactured by Tokyo Electron, and the film thickness d was measured. From the film thickness etched during the specified time using each gas (film thickness c - film thickness d), the film thickness etched in 1 minute was calculated and defined as the etching rate B (nm / min). The results are shown in Table 6 below.

[0645] The etching resistance of the film fired at 450°C or 550°C was compared with that of the film fired at 350°C, and the improvement effect of the etching resistance obtained by firing at 450°C or 550°C was calculated (etching rate B (nm / min) - etching rate A (nm / min)). The results are shown in Table 6 below.

[0646] The etching conditions are as follows.

[0647] Dry etching conditions in CF4 gas

[0648] Chamber pressure: 50mT

[0649] RF power (upper): 500W

[0650] RF power (lower): 300W

[0651] CF4 gas flow rate: 150sccm

[0652] CHF3 gas flow rate: 50sccm

[0653] Time: 30 seconds

[0654] [Table 6]

[0655]

[0656]

[0657] As shown in Table 6, in Examples 4-1 to 4-15 using the resist underlayer film forming composition (UDL-1 to 12) of the present invention, the etching rate of the film fired at 350°C using CF4 gas was 70 nm / min or less, showing excellent etching resistance. In addition, the etching resistance of the film fired at 450°C or 550°C in a nitrogen environment with an oxygen concentration of 0.2% or less was even better, and an improvement of 10 nm / min or more in etching rate was observed compared to the film fired at 350°C. It is presumed that the resist underlayer film forming composition of the present invention is a high-carbon material that actively undergoes thermal decomposition of the cured film due to high-temperature baking, so when fired at 450°C or 550°C, decomposition and recombination of carbon bonds occur, and the cured film becomes dense. In Examples 4-2 to 4-5, Examples 4-7, and 4-8, densification was promoted by increasing the temperature of high-temperature firing in a nitrogen atmosphere from 450° C. to 550° C., resulting in improved high etching resistance.

[0658] Furthermore, when comparing Examples 4-1 to 4-5, the larger the condensed aromatic ring in the polymer used in the resist underlayer film forming composition of the present invention, the higher the etching resistance of the film tends to be. In the experiment, the composition containing the polymer (A3) having an anthracene structure showed the highest etching resistance.

[0659] Examples 4-6 to 4-8 using random polymers (A4) and (A5) whose solvent solubility has been confirmed to be improved, and Examples 4-11 to 4-14 adding blended resins and cross-linking agents that have been confirmed to improve film thickness uniformity during high-temperature treatment, all achieved etching resistance results that were comparable to those of Examples 4-4 and 4-5 using polymer (A3).

[0660] Compared with Examples 4-10 using a resin polymer (A7) similar to polymer (A3) in that the aromatic group represented by Ar in the above general formula (1) is anthracene, polymer (A3) shows excellent etching resistance. Polymer (A7) has a different synthesis formula from polymer (A3) and is synthesized by Alternative Method 2. As a result, similar to the result of solubility, it is difficult to control the molecular weight in the synthesis by Alternative Method 2, so it is speculated that the molecular weight of polymer (A7) becomes larger than that of polymer (A3), resulting in less thermal decomposition. Based on this result, it can be seen that the composition containing the polymer synthesized by Alternative Method 1 is better than the polymer synthesized by Alternative Method 2. On the other hand, it can be seen that when Ar is anthracene, the molecular weight of the polymer is preferably 800 or less.

[0661] Comparative Example 4-1, which uses a comparative polymer (R1) of a novolac resin having a methylene group like the polymer (resin) contained in the resist underlayer film forming composition of the present invention, has poor etching resistance of the film fired at 350°C and poor etching resistance after firing at 550°C because the comparative polymer (R1) is composed of repeating units containing a hydroxyl group and the resin itself has a large amount of oxygen. In addition, Comparative Example 4-2, which uses a comparative polymer (R2) of the same novolac resin and relatively high carbon, has relatively good etching resistance of the film fired at 350°C, but the improvement rate of etching resistance after firing at 550°C is small. It is presumed that the reason is that the resin has high heat resistance and high carbonization and densification are difficult to proceed at high temperature firing.

[0662] Comparative Example 4-3 using a high carbon and rigid comparative polymer (R3) has good etching resistance at 350°C, which is comparable to that of the resin used in the examples of the present invention, because the repeating unit of the comparative polymer (R3) does not have an oxygen atom. However, the repeating unit of the comparative polymer (R3) does not have a group that promotes thermal decomposition, such as a methylene group, so the improvement rate of etching resistance of this resin at high temperature firing is small.

[0663] Comparative Example 4-4, which uses a comparative example polymer (R4) with the same structure as the resin of the present invention but a smaller molecular weight, shows the same improvement rate in etching resistance after high-temperature firing as the product of the present invention. Perhaps due to the significantly insufficient heat resistance, the film thickness uniformity and filling / flatness during high-temperature firing are not ideal, making it difficult to use as an anti-etching agent underlayer film.

[0664] Comparative Examples 4-5, which used both the COPNA resin component and the comparative polymer (R6) having a substituted aromatic group, had a large thermal decomposition, but the degree of improvement in etching resistance was less than that of the resin of the present invention. The reason is presumably that the ratio of the COPNA resin component, which is easy to form an amorphous carbon film by thermal decomposition, was small.

[0665] Comparative Examples 4-6 to 9 using comparative polymers (R7) to (R10) having a resin structure similar to that used in the embodiments of the present invention also showed good etching resistance of the films fired at 350°C, but the improvement rate of etching resistance fired at 550°C was small. It is believed that the reason is that, as in the case of R2 above, the heat resistance is increased due to the presence of repeating units having hydroxyl groups, and high carbonization and densification are difficult to achieve at high temperature firing.

[0666] Furthermore, it can be said that a composition containing a polymer having a structure represented by the general formulae (1) to (3) which forms a resist underlayer film having excellent etching resistance is preferable.

[0667] [Example 5 and Comparative Example 5: Pattern Formation Method]

[0668] The above-mentioned resist underlayer film forming compositions (UDL-1 to 12 and comparative examples UDL-1 to 9) were coated on a silicon wafer substrate formed with a SiO2 film having a trench pattern (trench width 10 μm, trench depth 0.10 μm), and the coating was fired at 350°C for 60 seconds in the atmosphere. Thereafter, the coating was heated at 550°C for 90 seconds in a nitrogen environment with an oxygen concentration of 0.2% or less to form a resist underlayer film with a film thickness of 100 nm. Then, a resist intermediate layer material (SOG-1) containing silicon atoms was coated on the resist underlayer film, and the coating was baked at 220°C for 60 seconds to form a resist intermediate layer film with a film thickness of 20 nm. Then, an ArF single-layer resist of the resist upper layer material was coated on the resist intermediate layer film, and the coating was baked at 105°C for 60 seconds to form a photoresist film with a film thickness of 100 nm. Then, a wet protection film material (TC-1) was coated on the photoresist film, and the coating was baked at 90°C for 60 seconds to form a protection film with a film thickness of 50 nm.

[0669] The silicon-containing resist intermediate layer material (SOG-1) was prepared as follows. A polymer represented by an ArF silicon-containing intermediate film polymer (SiP1) and a crosslinking catalyst (CAT1) were dissolved in an organic solvent containing 0.1% by mass of FC-4430 (manufactured by Sumitomo 3M Co., Ltd.) in the proportions shown in Table 7. The obtained mixture was filtered through a fluororesin filter having a pore size of 0.10 μm to prepare the silicon-containing resist intermediate layer material (SOG-1).

[0670] [Table 7]

[0671]

[0672] The structural formulas of the ArF silicon-containing interlayer polymer (SiP1) and the crosslinking catalyst (CAT1) used are shown below.

[0673] [Chemistry 91]

[0674]

[0675] The resist upper film material (ArF single-layer resist) was prepared according to the following procedure. First, the polymer (RP1), the acid generator (PAG1), and the basic compound (Amine1) were dissolved in a solvent containing 0.1% by mass of the surfactant FC-4430 (manufactured by Sumitomo 3M Co., Ltd.) according to the proportions shown in Table 8. The obtained mixture was filtered with a 0.10 μm fluororesin filter to obtain the resist upper film material.

[0676] [Table 8]

[0677]

[0678] The polymer (RP1), the acid generator (PAG1), and the basic compound (Amine1) used for the resist upper layer film material (single-layer resist for ArF) are shown below.

[0679] [Chemistry 92]

[0680]

[0681] The wet protective film material (TC-1) was prepared according to the following procedure: First, the protective film polymer (PP1) was dissolved in an organic solvent according to the ratio in Table 9. The obtained mixture was filtered through a 0.10 μm fluororesin filter to obtain a wet protective film material.

[0682] [Table 9]

[0683]

[0684] The polymer (PP1) used in the wet protection film material (TC-1) is shown below.

[0685] [Chemistry 93]

[0686]

[0687] Next, the film was exposed with an ArF immersion exposure apparatus (manufactured by Nikon Co., Ltd.; NSR-S610C, NA1.30, σ0.98 / 0.65, 35-degree dipole s-polarized illumination, 6% half-step phase shift mask), baked (PEB) at 100°C for 60 seconds, and developed with a 2.38% by mass tetramethylammonium hydroxide (TMAH) aqueous solution for 30 seconds to obtain a 55nm1:1 positive line and space pattern (resist pattern).

[0688] Next, using the etching device Telius manufactured by Tokyo Electron, the resist pattern was used as a mask to perform etching on the resist intermediate layer material (SOG-1) containing silicon atoms by dry etching to form a hard mask pattern (SOG-1 pattern). The obtained SOG-1 pattern was used as a mask to etch the resist lower film to form a resist lower film pattern. Then, the obtained resist lower film pattern was used as a mask to perform etching on the SiO2 film. The etching conditions are as follows.

[0689] Transfer conditions of the resist pattern to the resist intermediate layer material containing silicon atoms (SOG-1).

[0690] Chamber pressure: 50mT

[0691] RF power (upper): 500W

[0692] RF power (lower): 300W

[0693] CF4 gas flow rate: 150sccm

[0694] CHF3 gas flow rate: 50sccm

[0695] Time: 15 seconds

[0696] Transfer conditions of the resist intermediate layer material (SOG-1) pattern containing silicon atoms to the resist underlayer film.

[0697] Chamber pressure: 10mT

[0698] RF power (upper): 1,000W

[0699] RF power (lower): 300W

[0700] CO2 gas flow rate: 320sccm

[0701] N2 gas flow rate: 80sccm

[0702] Time: 30 seconds

[0703] Transfer conditions of the resist underlayer film pattern to the SiO2 film.

[0704] Chamber pressure: 10mT

[0705] RF power (upper): 100W

[0706] RF power (lower): 800W

[0707] CF4 gas flow rate: 25sccm

[0708] CHF3 gas flow rate: 15sccm

[0709] O2 gas flow rate: 5sccm

[0710] Time: 100 seconds

[0711] The cross section of the pattern formed by the SiO2 film was observed with an electron microscope (S-4700) manufactured by Hitachi, Ltd. The results are shown in Table 10. "-" indicates that the film was not evaluated due to poor film formation.

[0712] [Table 10]

[0713]

[0714]

[0715] As shown in Table 10, in Examples 5-1 to 5-12 using the resist underlayer film forming composition (UDL-1 to 12) of the present invention, the resist upper film pattern was finally well transferred to the SiO2 film on the substrate, confirming that the resist underlayer film forming composition of the present invention is suitable for fine processing using the reuse multilayer resist method. On the other hand, in the above-mentioned etching resistance evaluation, Comparative Examples 5-1 to 5-3 and Comparative Examples UDL-1 to 3 and Comparative Examples UDL-6 to 9 were used to confirm that the etching resistance was insufficient compared to the resist underlayer film forming composition of the present invention. The pattern shape after substrate transfer etching was a vertical shape, but degradation of LWR after substrate processing was observed. In addition, Comparative Examples 5-4 and 5-5, in which voids occurred in the filling evaluation, pattern collapse occurred.

[0716] From the above, it can be understood that the composition for forming an anti-etching underlayer film of the present invention is extremely useful as an anti-etching underlayer film material used in a multilayer anti-etching method because it has significantly good dry etching resistance and a high degree of filling and / or flattening characteristics. Moreover, if the pattern forming method of the present invention uses it, even if the processed body is a substrate with height differences, a fine pattern can be formed with high precision.

[0717] This specification includes the following aspects.

[0718] [1] A composition for forming a resist underlayer film, characterized in that:

[0719] Containing (A) a polymer having a structure represented by the following general formula (1) as a repeating unit, and (B) an organic solvent,

[0720] The molecular weight of the polymer (A) is 300 to 3,000, and the polymer (A) does not contain a repeating unit containing a hydroxyl group as a substituent and does not contain a repeating unit containing a heteroaromatic ring.

[0721] [Chemistry 94]

[0722]

[0723] In the above formula (1), Ar is an unsubstituted divalent aromatic group having 6 to 30 carbon atoms.

[0724] [2] The resist underlayer film forming composition according to [1], wherein the aromatic group Ar is any of the following structures (1-a),

[0725] [Chemistry 95]

[0726]

[0727] In the above formula (1-a), * represents the bonding position to the methylene group in the above general formula (1).

[0728] [3] The resist underlayer film forming composition according to [1] or [2], wherein the aromatic group Ar is any one of naphthalene, anthracene, phenanthrene, and pyrene.

[0729] [4] The resist underlayer film forming composition according to any one of [1] to [3], wherein the polymer (A) is a copolymer having two repeating units represented by the following general formula (2):

[0730] [Chemistry 96]

[0731]

[0732] In the above formula (2), Ar1 is any one of naphthalene, anthracene, phenanthrene, and pyrene, Ar2 is any one of a structure different from that of Ar1 and selected from the following formula (1-a), a+b is 100, 30≤a≤99, 1≤b≤70,

[0733] [Chemistry 97]

[0734]

[0735] [5] The resist underlayer film forming composition according to [4], wherein the polymer (A) of the copolymer having two types of repeating units represented by the general formula (2) is a polymerization reaction product of a monomer represented by the following formula (2-a) and a monomer represented by the following formula (2-b),

[0736] [Chemistry 98]

[0737] Ar1-CH2-X (2-a)

[0738] Ar2-CH2-X (2-b)

[0739] In the above formula, Ar1 is any one of naphthalene, anthracene, phenanthrene, and pyrene, Ar2 is a structure different from Ar1 and is any one selected from the above formula (1-a), and X is a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, or a halogen group.

[0740] [6] The resist underlayer film forming composition as described in [5], wherein Ar1 in the above formula (2) is anthracene.

[0741] [7] The resist underlayer film forming composition according to any one of [1] to [6], wherein the molecular weight of the polymer (A) is 300 to 1,500.

[0742] [8] The resist underlayer film forming composition according to any one of [1] to [7], wherein the polymer (A) has a terminal sealing group represented by the following general formula (3):

[0743] [Chemistry 99]

[0744]

[0745] In the above formula (3), * is a bonding portion with a methylene group in the above formula (1), d is an integer of 1-9, and e is an integer of 0-2.

[0746] [9] The resist underlayer film forming composition according to any one of [1] to [8], wherein the resist underlayer film forming composition further contains (C) a blending resin which is a phenolic resin or a resin containing a phenolic hydroxyl group.

[0747]

[10] The resist underlayer film forming composition according to [9], wherein the molecular weight of the (C) blended resin is 4,000 to 12,000.

[0748]

[11] The resist underlayer film forming composition according to [9] or

[10] , wherein the amount of the (C) blended resin added is 10 to 100 parts by mass relative to 100 parts by mass of the (A) polymer.

[0749]

[12] The resist underlayer film forming composition according to any one of [9] to

[11] , wherein the (C) blended resin is a resin represented by any of the following general formulas (C-1), (C-2) and (C-3),

[0750] [Chemical 100]

[0751]

[0752] In the above formula (C-1), R is a monovalent to trivalent organic group having 1 to 20 carbon atoms which may contain an oxygen atom, o is an integer of 1 to 3, and p is an integer of 1 to 3.

[0753] [Chemistry 101]

[0754]

[0755] In the above formula (C-2), q is an integer of 0 or 1, and r is an integer of 1-6.

[0756] [Chemistry 102]

[0757]

[0758] In the above formula (C-3), s is an integer of 0 or 1, t is an integer of 1 to 6, and u is an integer of 0 or 1.

[0759]

[13] The resist underlayer film forming composition according to any one of [1] to

[12] , wherein the resist underlayer film forming composition further contains (D) a crosslinking agent having a structure represented by the following general formula (4):

[0760] [Chemistry 103]

[0761]

[0762] In the above formula (4), Ar3 and Ar4 are each a benzene ring or a naphthalene ring which may have a substituent, and R A represents a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, and W is a group represented by the following general formula (5).

[0763] [Chemistry 104]

[0764]

[0765] In the above formula (5), * represents a bonding position.

[0766]

[14] A composition for forming an anti-etching underlayer film as described in any one of [1] to

[13] , wherein the composition for forming an anti-etching underlayer film further contains a (E) fluidity promoter having a weight reduction rate of less than 30% between 30°C and 190°C and a weight reduction rate of more than 98% between 30°C and 350°C.

[0767]

[15] The resist underlayer film forming composition according to

[14] , wherein the fluidity enhancer (E) contains one or more compounds selected from the group consisting of compounds represented by the following general formulae (i) to (iii):

[0768] [Chemistry 105]

[0769]

[0770] In the above formula (i), R1 is independently a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms which may be substituted. W1 is a phenylene group or a divalent group represented by the following general formula (i-1). W2 and W3 are each a single bond or any divalent group represented by the following general formula (i-2). g is an integer of 1 to 5, and h is an integer of 0 to 10.

[0771] [Chemistry 106]

[0772]

[0773] In the above formula (i-1), * represents the bonding position, R 10 , R 11 , R 12 , R 13 W is a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms. 10 and W 11 Each independently represents a single bond or a carbonyl group. i and j are integers of 0 to 10, and i+j≥1.

[0774] [Chemistry 107]

[0775]

[0776] In the above formula (i-2), * represents a bonding position.

[0777] [Chemistry 108]

[0778]

[0779] In the above formula (ii), R2 is independently a hydrogen atom or an organic group having 1 to 10 carbon atoms which may be substituted. W4 is a divalent group represented by the following general formula (ii-1). W5 is a single bond or any divalent group represented by the following general formula (ii-2). k is an integer of 0 to 5, and l is an integer of 2 to 10.

[0780] [Chemistry 109]

[0781]

[0782] In the above formula (ii-1), * represents the bonding position, R 20 , R 21 , R 22 and R 23 Each is a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms. m and n are integers of 0 to 10, and m+n≥1.

[0783] [Chemistry 110]

[0784]

[0785] In the above formula (ii-2), * represents a bonding position.

[0786] [Chemistry 111]

[0787]

[0788] In the above formula (iii), R3 and R4 are each a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms which may be substituted, and may be bonded to form a cyclic structure. R5 and R6 are each an organic group having 1 to 10 carbon atoms, and R5 is a group containing an aromatic ring or one of the divalent groups represented by the following general formula (iii-1). W6 and W7 are each a single bond or any divalent group represented by the following general formula (iii-2), and at least one of them is a divalent group represented by any of (iii-2).

[0789] [Chemistry 112]

[0790]

[0791] In the above formula (iii-1), * represents the bonding position, W30 It is an organic group having 1 to 4 carbon atoms.

[0792] [Chemistry 113]

[0793]

[0794] In the above formula (iii-2), * represents a bonding position.

[0795]

[16] The resist underlayer film forming composition according to any one of [1] to

[15] , wherein the resist underlayer film forming composition further comprises

[0796] (F) surfactant,

[0797] (G) an acid generator, and

[0798] (H) Plasticizer

[0799] One or more of the following.

[0800]

[17] A pattern forming method is a method for forming a pattern on a processed substrate, characterized by comprising the following steps:

[0801] (I-1) applying the resist underlayer film forming composition as described in any one of [1] to

[16] on a substrate to be processed to obtain a coating film, and heat-treating the coating film to form a resist underlayer film,

[0802] (I-2) forming a resist upper layer film on the resist lower layer film using a photoresist material,

[0803] (I-3) after pattern exposure of the resist upper layer film, developing with a developer to form a pattern on the resist upper layer film,

[0804] (I-4) using the patterned resist upper film as a mask, transferring the pattern to the resist lower film by dry etching, and

[0805] (I-5) The substrate to be processed is processed using the patterned resist underlayer film as a mask to form a pattern on the substrate to be processed.

[0806]

[18] A pattern forming method is a method for forming a pattern on a processed substrate, characterized by comprising the following steps:

[0807] (II-1) applying the resist underlayer film forming composition as described in any one of [1] to

[16] on a substrate to be processed to obtain a coating film, and heat-treating the coating film to form a resist underlayer film,

[0808] (II-2) forming a resist intermediate film on the resist underlayer film,

[0809] (II-3) forming a resist upper layer film on the resist intermediate film using a photoresist material,

[0810] (II-4) after pattern exposure of the resist upper layer film, developing with a developer to form a pattern on the resist upper layer film,

[0811] (II-5) using the patterned resist upper film as a mask, transferring the pattern to the resist intermediate film by dry etching,

[0812] (II-6) using the resist intermediate film to which the pattern has been transferred as a mask, transferring the pattern to the resist lower layer film by dry etching, and

[0813] (II-7) The substrate to be processed is processed using the patterned resist underlayer film as a mask to form a pattern on the substrate to be processed.

[0814]

[19] A pattern forming method is a method for forming a pattern on a processed substrate, characterized by comprising the following steps:

[0815] (III-1) applying the resist underlayer film forming composition as described in any one of [1] to

[16] on a substrate to be processed to obtain a coating film, and heat-treating the coating film to form a resist underlayer film,

[0816] (III-2) forming an inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film, and a silicon oxide nitride film on the resist underlayer film,

[0817] (III-3) forming an organic thin film on the aforementioned inorganic hard mask intermediate film,

[0818] (III-4) forming a resist upper layer film on the aforementioned organic thin film using a photoresist material,

[0819] (III-5) after pattern exposure of the resist upper layer film, developing with a developer to form a pattern on the resist upper layer film,

[0820] (III-6) using the patterned resist upper layer film as a mask, transferring the pattern to the organic thin film and the inorganic hard mask intermediate film by dry etching,

[0821] (III-7) using the inorganic hard mask intermediate film to which the pattern has been transferred as a mask, transferring the pattern to the resist underlayer film by dry etching, and

[0822] (III-8) The substrate to be processed is processed using the patterned resist underlayer film as a mask to form a pattern on the substrate to be processed.

[0823]

[20] The pattern forming method according to any one of

[17] to

[19] , wherein a substrate having a structure with a height of 30 nm or more or a height difference is used as the substrate to be processed.

[0824]

[21] A method for forming a resist underlayer film, which is a method for forming a resist underlayer film that acts as an organic planar film used in a manufacturing step of a semiconductor device, characterized by:

[0825] A coating film is obtained by spin-coating a resist underlayer film forming composition as described in any one of [1] to

[16] on a substrate to be processed, and the coating film is hardened by heat treatment at a temperature in the range of 450°C to 800°C for 10 to 600 seconds to form a resist underlayer film.

[0826]

[22] A method for forming a resist underlayer film, which is a method for forming a resist underlayer film that acts as an organic planar film used in a manufacturing step of a semiconductor device, characterized by:

[0827] A coating film is obtained by spin-coating a resist underlayer film forming composition as described in any one of [1] to

[16] on a substrate to be processed, and the coating film is hardened by heat treatment in a gas environment with an oxygen concentration of 1% to 21% to form a resist underlayer film.

[0828]

[23] A method for forming a resist underlayer film, which is a method for forming a resist underlayer film that acts as an organic planar film used in a manufacturing step of a semiconductor device, characterized by:

[0829] The resist underlayer film forming composition as described in any one of [1] to

[16] is spin-coated on a substrate to be processed to obtain a coating film, and the coating film is hardened by heat treatment in a gas environment with an oxygen concentration of less than 1%, thereby forming a resist underlayer film.

[0830]

[24] A method for forming a resist underlayer film as described in any one of

[21] to

[23] , wherein a substrate having a structure with a height of 30 nm or more or a height difference is used as the aforementioned processed substrate.

[0831] The present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments are illustrative only, and any device having substantially the same configuration and exhibiting the same function and effect as the technical concept described in the claims of the present invention is included in the technical scope of the present invention.

[0832] Description of Reference Numerals

[0833] 1:Support substrate

[0834] 1A: Processed substrate

[0835] 2: Processing layer

[0836] 2a: Pattern (pattern formed on the processed layer)

[0837] 3: Resist lower layer film

[0838] 3a: Resist lower film pattern

[0839] 4: Resist interlayer

[0840] 4a: Resist interlayer pattern

[0841] 5: Resist upper film

[0842] 5a: Resist upper film pattern

[0843] 6: Exposure part

[0844] 9: Base substrate with dense line & space pattern

[0845] 10: Resist lower layer film

[0846] 11: Base substrate with dense line & space pattern

[0847] 12:Filling film

[0848] Delta 12: The height difference between the densely line patterned part and the non-line patterned part of the filling film

Claims

1. A composition for forming a resist underlayer film, characterized in that: Containing (A) a polymer having a structure represented by the following general formula (1) as a repeating unit, and (B) an organic solvent, The molecular weight of the polymer (A) is 300 to 3,000, and the polymer (A) does not contain a repeating unit containing a hydroxyl group as a substituent and does not contain a repeating unit containing a heteroaromatic ring. In the above formula (1), Ar is an unsubstituted divalent aromatic group having 6 to 30 carbon atoms.

2. The resist underlayer film forming composition according to claim 1, wherein The aromatic group Ar is any of the following structures (1-a), In the above formula (1-a), * represents the bonding position to the methylene group in the general formula (1).

3. The resist underlayer film forming composition according to claim 1, wherein The aromatic group Ar is any of naphthalene, anthracene, phenanthrene, and pyrene.

4. The resist underlayer film forming composition according to claim 1, wherein The polymer (A) is a copolymer having two types of repeating units represented by the following general formula (2): In the above formula (2), Ar1 is any one of naphthalene, anthracene, phenanthrene, and pyrene, Ar2 is any one of a structure different from that of Ar1 and selected from the following formula (1-a), a+b is 100, 30≤a≤99, 1≤b≤70, 5. The resist underlayer film forming composition according to claim 4, wherein The polymer (A) of the copolymer having two types of repeating units represented by the general formula (2) is a polymerization reaction product of a monomer represented by the following formula (2-a) and a monomer represented by the following formula (2-b), Ar1-CH2-X (2-a) Ar2-CH2-X (2-b) In the above formula, Ar1 is any one of naphthalene, anthracene, phenanthrene, and pyrene, Ar2 is a structure different from that of Ar1 and is any one selected from the formula (1-a), and X is a hydroxyl group, an alkoxy group having 1 to 4 carbon atoms, or a halogen group.

6. The resist underlayer film forming composition according to claim 5, wherein Ar1 in the formula (2) is anthracene.

7. The resist underlayer film forming composition according to claim 1, wherein The molecular weight of the polymer (A) is 300 to 1,500.

8. The resist underlayer film forming composition according to claim 1, wherein The polymer (A) has a terminal sealing group represented by the following general formula (3): In the above formula (3), * is a bonding portion with the methylene group in the above formula (1), d is an integer of 1-9, and e is an integer of 0-2.

9. The resist underlayer film forming composition according to claim 1, wherein The resist underlayer film-forming composition further contains (C) a blending resin which is a phenol resin or a phenolic hydroxyl group-containing resin.

10. The resist underlayer film forming composition according to claim 9, wherein The molecular weight of the (C) blended resin is 4,000 to 12,000.

11. The resist underlayer film forming composition according to claim 9, wherein The amount of the (C) blending resin added is 10 to 100 parts by mass based on 100 parts by mass of the (A) polymer.

12. The resist underlayer film forming composition according to claim 9, wherein The (C) blended resin is a resin represented by any of the following general formulas (C-1), (C-2) and (C-3), In the above formula (C-1), R is a monovalent to trivalent organic group having 1 to 20 carbon atoms which may contain an oxygen atom, o is an integer of 1 to 3, and p is an integer of 1 to 3. In the above formula (C-2), q is an integer of 0 or 1, and r is an integer of 1 to 6. In the above formula (C-3), s is an integer of 0 or 1, t is an integer of 1 to 6, and u is an integer of 0 or 1.

13. The resist underlayer film forming composition according to claim 1, wherein The resist underlayer film-forming composition further contains (D) a crosslinking agent having a structure represented by the following general formula (4): In the above formula (4), Ar3 and Ar4 are each a benzene ring or a naphthalene ring which may have a substituent, and R A represents a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, and W is a group represented by the following general formula (5), In the above formula (5), * represents a bonding position.

14. The resist underlayer film forming composition according to claim 1, wherein The resist underlayer film forming composition further contains (E) a fluidity enhancer having a weight reduction rate of less than 30% from 30° C. to 190° C. and a weight reduction rate of 98% or more from 30° C. to 350° C.

15. The resist underlayer film forming composition according to claim 14, wherein The (E) fluidity enhancer contains one or more compounds selected from the group consisting of compounds represented by the following general formulae (i) to (iii): In the above formula (i), R1 is independently a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms which may be substituted, W1 is a phenylene group or a divalent group represented by the following general formula (i-1), W2 and W3 are each a single bond or any divalent group represented by the following general formula (i-2), g is an integer of 1 to 5, and h is an integer of 0 to 10. In the above formula (i-1), * represents the bonding position, R 10 , R 11 , R 12 , R 13 is a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms, W 10 and W 11 Each independently represents a single bond or a carbonyl group, i and j are integers from 0 to 10, i+j≥1, In the above formula (i-2), * represents the bonding position, In the above formula (ii), R2 is independently a hydrogen atom or an organic group having 1 to 10 carbon atoms which may be substituted, W4 is a divalent group represented by the following general formula (ii-1), W5 is a single bond or any divalent group represented by the following general formula (ii-2), k is an integer of 0 to 5, and l is an integer of 2 to 10. In the above formula (ii-1), * represents the bonding position, R 20 , R 21 , R 22 and R 23 Each is a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms, m and n are integers of 0 to 10, and m+n≥1, In the above formula (ii-2), * represents the bonding position, In the above formula (iii), R3 and R4 are each a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms which may be substituted and may be bonded to form a cyclic structure, R5 and R6 are each an organic group having 1 to 10 carbon atoms, R5 is a group containing an aromatic ring or one of the divalent groups represented by the following general formula (iii-1), W6 and W7 are each a single bond or any divalent group represented by the following general formula (iii-2), at least one of which is a divalent group represented by any of (iii-2), In the above formula (iii-1), * represents the bonding position, W 30 is an organic group having 1 to 4 carbon atoms, In the above formula (iii-2), * represents a bonding position.

16. The resist underlayer film forming composition according to claim 1, wherein The resist underlayer film forming composition further comprises (F) surfactant, (G) an acid generator, and (H) Plasticizer One or more of the following.

17. A method for forming a pattern on a processed substrate, The method is characterized by having the following steps: (I-1) Coating on the substrate to be processed (I-2) forming a resist upper film on the resist underlayer film by using a photoresist material, (I-3) after pattern exposure of the resist upper layer film, developing with a developer to form a pattern on the resist upper layer film, (I-4) using the patterned resist upper film as a mask, transferring the pattern to the resist lower film by dry etching, and (I-5) The substrate to be processed is processed using the patterned resist underlayer film as a mask to form a pattern on the substrate to be processed.

18. A method for forming a pattern on a processed substrate, The method is characterized by having the following steps: (II-1) Coating on the substrate to be processed A coating film is obtained by using the resist underlayer film forming composition according to any one of claims 1 to 16, and the coating film is heat-treated to form a resist underlayer film. (II-2) forming a resist intermediate film on the resist underlayer film, (II-3) forming a resist upper layer film on the resist intermediate film using a photoresist material, (II-4) after pattern exposure of the resist upper layer film, developing with a developer to form a pattern on the resist upper layer film, (II-5) using the patterned resist upper layer film as a mask, transferring the pattern to the resist intermediate film by dry etching, (II-6) using the resist intermediate film to which the pattern has been transferred as a mask, transferring the pattern to the resist lower layer film by dry etching, and (II-7) The substrate to be processed is processed using the patterned resist underlayer film as a mask to form a pattern on the substrate to be processed.

19. A method for forming a pattern on a processed substrate, The method is characterized by having the following steps: (III-1) Coating on the substrate to be processed A coating film is obtained by using the resist underlayer film forming composition according to any one of claims 1 to 16, and the coating film is heat-treated to form a resist underlayer film. (III-2) forming an inorganic hard mask intermediate film selected from a silicon oxide film, a silicon nitride film, and a silicon oxide nitride film on the resist underlayer film, (III-3) forming an organic thin film on the inorganic hard mask intermediate film, (III-4) forming a resist upper layer film on the organic thin film using a photoresist material, (III-5) after pattern exposure of the resist upper layer film, developing with a developer to form a pattern on the resist upper layer film, (III-6) using the patterned resist upper layer film as a mask, transferring the pattern to the organic thin film and the inorganic hard mask intermediate film by dry etching, (III-7) using the inorganic hard mask intermediate film to which the pattern has been transferred as a mask, transferring the pattern to the resist underlayer film by dry etching, and (III-8) The substrate to be processed is processed using the patterned resist underlayer film as a mask to form a pattern on the substrate to be processed.

20. The pattern forming method according to claim 17, wherein a substrate having a structure or a height difference of 30 nm or more is used as the substrate to be processed.

21. The pattern forming method according to claim 18, wherein a substrate having a structure or a height difference of 30 nm or more is used as the substrate to be processed.

22. The pattern forming method according to claim 19, wherein a substrate having a structure or a height difference of 30 nm or more is used as the substrate to be processed.

23. A method for forming a resist underlayer film, which is a method for forming a resist underlayer film serving as an organic planar film used in a manufacturing step of a semiconductor device, characterized by: The resist underlayer film forming composition according to any one of claims 1 to 16 is spin-coated on a substrate to be processed to obtain a coating film, and the coating film is heat-treated at a temperature of 450° C. to 800° C. for 10 to 600 seconds to harden it to form a resist underlayer film.

24. A method for forming a resist underlayer film, which is a method for forming a resist underlayer film serving as an organic planar film used in a manufacturing step of a semiconductor device, characterized by: The resist underlayer film forming composition according to any one of claims 1 to 16 is spin-coated on a substrate to be processed to obtain a coating film, and the coating film is heat-treated in a gas atmosphere with an oxygen concentration of 1% to 21% to harden it, thereby forming a resist underlayer film.

25. A method for forming a resist underlayer film, which is a method for forming a resist underlayer film serving as an organic planar film used in a manufacturing step of a semiconductor device, characterized by: The resist underlayer film forming composition according to any one of claims 1 to 16 is spin-coated on a substrate to be processed to obtain a coating film, and the coating film is heat-treated in a gas atmosphere having an oxygen concentration of less than 1% to be cured to form a resist underlayer film.

26. The resist underlayer film forming method according to claim 23, wherein a substrate having a structure or a height difference of 30 nm or more is used as the substrate to be processed.

27. The resist underlayer film forming method according to claim 24, wherein a substrate having a structure or a height difference of 30 nm or more is used as the substrate to be processed.

28. The resist underlayer film forming method according to claim 25, wherein a substrate having a structure or a height difference of 30 nm or more is used as the substrate to be processed.

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