Composition for resist underlayer film formation, pattern formation method, and resist underlayer film formation method

Abstract

To provide a composition for resist underlayer film formation which enables formation of a resist underlayer film exhibiting extremely excellent dry etching resistance to conventional organic underlayer film materials.SOLUTION: A composition for resist underlayer film formation contains a polymer (A) having a structure represented by the following general formula (1) as a repeating unit, and an organic solvent (B), wherein a molecular weight of the polymer (A) is 300 to 3,000, and the polymer (A) does not contain both a repeating unit containing a hydroxyl group as a substituent and a repeating unit containing a heteroaromatic ring. In the formula (1), Ar is a non-substituted divalent aromatic group having 6 to 30 carbon atoms.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a composition for forming a resist underlayer film, a pattern forming method, and a method for forming a resist underlayer film, and more particularly to a composition for forming a resist underlayer film that can be used for fine patterning by a multilayer resist method in a semiconductor device manufacturing process, a pattern forming method using the material, and a method for forming a resist underlayer film. [Background technology]

[0002] As LSIs become more highly integrated and faster, pattern dimensions are becoming finer at a rapid pace. Lithography technology has achieved the formation of fine patterns by shortening the wavelength of light sources and selecting appropriate resist compositions to match them, in line with this miniaturization. The core of this technology is a positive photoresist composition used in a single layer. This single-layer positive photoresist composition has a skeleton in the resist resin that is resistant to dry etching using chlorine- or fluorine-based gas plasma, and also has a switching mechanism that dissolves the exposed parts, forming a pattern by dissolving the exposed parts, and then dry etching the substrate to be processed using the remaining resist pattern as an etching mask.

[0003] However, when the thickness of the photoresist film used is made finer, that is, when the pattern width is made smaller, the resolution performance of the photoresist film decreases, and when an attempt is made to develop the photoresist film into a pattern using a developer, the so-called aspect ratio becomes too large, resulting in problems such as pattern collapse. For this reason, the photoresist film has been made thinner as the pattern becomes finer.

[0004] On the other hand, in the processing of a substrate to be processed, a method is usually used in which a photoresist film on which a pattern is formed is used as an etching mask to process the substrate by dry etching, but in reality, there is no dry etching method that can obtain perfect etching selectivity between the photoresist film and the substrate to be processed. Therefore, there is a problem that the photoresist film is also damaged and collapsed during processing of the substrate, and the resist pattern cannot be accurately transferred to the substrate to be processed. Therefore, with the miniaturization of patterns, a higher dry etching resistance has been required for the resist composition. However, on the other hand, in order to increase the resolution, a resin with low light absorption at the exposure wavelength has been required for the resin used in the photoresist composition. Therefore, as the exposure light has become shorter in wavelength from i-line to KrF and ArF, the resin has also changed to novolac resin, polyhydroxystyrene, and resin with an aliphatic polycyclic skeleton. However, in reality, the etching speed under dry etching conditions during substrate processing has become faster, and recent photoresist compositions with high resolution tend to have weaker etching resistance.

[0005] This means that the substrate must be dry etched using a thinner photoresist film with weaker etching resistance, and there is an urgent need to secure materials and processes for this processing step.

[0006] One method for solving such problems is the multi-layer resist method, in which a resist intermediate film having a different etching selectivity from a photoresist film (i.e., a resist upper layer film) is interposed between the resist upper layer film and a substrate to be processed, a pattern is obtained in the resist upper layer film, and the resist upper layer film pattern is used as a dry etching mask to transfer the pattern to the resist intermediate film by dry etching, and the resist intermediate film is further used 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 performed using a general resist composition used in a single-layer resist method. In this three-layer resist method, for example, an organic film made of novolac resin or the like is formed on a substrate to be processed as a resist underlayer film, a silicon-containing resist intermediate film is formed on the organic film as a resist intermediate film, and a normal organic photoresist film is formed on the organic film as a resist upper layer film. When dry etching is performed using fluorine-based gas plasma, the organic resist upper layer film has a good etching selectivity to the silicon-containing resist intermediate film, so that the resist upper layer 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 if a resist composition that is difficult to form a pattern with a sufficient film thickness for directly processing a substrate to be processed or a resist composition that does not have sufficient dry etching resistance for processing a substrate is used, a pattern can be transferred to the silicon-containing resist intermediate film (resist intermediate film), and then, by performing pattern transfer by dry etching using oxygen-based or hydrogen-based gas plasma, a pattern of an organic film (resist underlayer film) made of novolac resin or the like that has sufficient dry etching resistance for processing a substrate can be obtained. As the above-mentioned resist underlayer film, many films are already known, for example, the one described in Patent Document 1.

[0008] On the other hand, in recent years, the miniaturization of DRAM memories has accelerated, and the need for a resist underlayer film having further improved dry etching resistance and excellent filling and planarization properties has increased. As a coating-type organic underlayer film material having excellent filling and planarization properties, for example, the one described in Patent Document 2 has been reported, but in terms of application to the latest generation, there are concerns about dry etching resistance, and the application limit of conventional coating-type organic underlayer film materials is approaching.

[0009] In response to the above problem, Patent Document 3 reports that the etching resistance during substrate processing can be improved by heating the resist underlayer film in an atmosphere with an oxygen concentration of less than 1% by volume at a temperature of 450° C. to 800° C. However, many of the resist underlayer films used in the above examples contain resins or compounds containing hydroxyl groups or propargyl groups, and oxygen atoms remain in the film, which is considered to be undesirable from the viewpoint of etching resistance.

[0010] Patent Document 4 reports a resist underlayer film material containing a condensed polycyclic polynuclear aromatic (COPNA) resin. Although the flatness of the cured film when treated at 400°C has been discussed, there is no example of forming a cured film by baking in an inert gas at over 500°C, and the change in etching resistance of the cured film formed by high-temperature treatment under an inert gas has not been clarified. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] JP 2004-205685 A [Patent Document 2] JP 2017-119671 A [Patent Document 3] JP 2016-206676 A [Patent Document 4] JP 2017-092457 A Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a composition for forming a resist underlayer film, which is capable of forming a resist underlayer film that exhibits extremely superior dry etching resistance compared to conventional organic underlayer film materials, a pattern formation method using the composition as a resist underlayer film material, and a method for forming a resist underlayer film using the composition. [Means for solving the problem]

[0013] In order to solve the above problems, the present invention provides a composition for forming a resist underlayer film, comprising: A polymer (A) having a repeating unit represented by the following general formula (1): (B) Organic solvent Contains A composition for forming a resist underlayer film, wherein the molecular weight of the polymer (A) is 300 to 3,000, and the polymer (A) does not contain any repeating unit having a hydroxyl group as a substituent, nor any repeating unit having a heteroaromatic ring. [ka] (In the above formula (1), Ar is an unsubstituted divalent aromatic group having 6 to 30 carbon atoms.)

[0014] In the case of a composition for forming a resist underlayer film containing the polymer (A) having the structure represented by the above general formula (1), since the polymer (A) does not contain a polymer constituted of a repeating unit having a hydroxy group and / or a heteroaromatic ring, it is possible to form, for example, by thermal curing, a resist underlayer film (high carbon film) having excellent dry etching resistance during substrate processing.

[0015] In addition, if the molecular weight is within the above range, not only is the composition excellent in solvent solubility, but it also exhibits good thermal decomposition by high-temperature treatment. In the composition for forming a resist underlayer film of the present invention, the dissociation and recombination of the carbon bonds of the (A) polymer are promoted by thermal decomposition, resulting in a diamond-like carbon structure, and a resist underlayer film having a high carbon content and excellent etching resistance can be formed.

[0016] The aromatic group Ar preferably has any one of the following structures (1-a). [ka] (In the above formula (1-a), * indicates the bonding position with the methylene group (CH2) in the general formula (1).)

[0017] When the aromatic group Ar has any of the above structures (1-a), it contains a methylene group that is easily thermally decomposed in addition to a high carbon density aromatic ring, and thus dissociation and recombination of carbon bonds are promoted during high temperature treatment, making it possible to form a resist underlayer film having a diamond-like carbon structure.

[0018] The aromatic group Ar is preferably any one of naphthalene, anthracene, phenanthrene, and pyrene.

[0019] From the viewpoint of solvent solubility and productivity, the aromatic group Ar is preferably any one of naphthalene, anthracene, phenanthrene, and pyrene.

[0020] The polymer (A) is preferably a copolymer having two types of repeating units represented by the following general formula (2). [ka] (In the above formula (2), Ar1 is any one of naphthalene, anthracene, phenanthrene, and pyrene, and Ar2 has a structure different from Ar1 and is any one selected from the following formula (1-a). a+b is 100, 30≦a≦99, and 1≦b≦70.) [ka]

[0021] A composition for forming a resist underlayer film that contains the polymer (A) having the structure represented by the above general formula (2) can increase the solvent solubility while maintaining a high carbon content of the composition.

[0022] In this case, it is more preferable that the polymer (A), which is a copolymer having two types of repeating units represented by the above 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). [ka] (In the above formula, Ar1 is any one of naphthalene, anthracene, phenanthrene, and pyrene, Ar2 has a structure different from Ar1 and is any one selected from the above formula (1-a), and X is a hydroxy group, an alkoxy group having 1 to 4 carbon atoms, or a halogen group.)

[0023] The polymer (A) obtained by the polymerization reaction of the monomers represented by the above formulas (2-a) and (2-b) is a polymer containing different Ar structures randomly. Therefore, when this polymer is used in a resist underlayer film-forming composition, a resist underlayer film-forming composition having excellent solvent solubility can be provided.

[0024] It is further preferable that Ar1 in the formula (2) is anthracene.

[0025] Such a resist underlayer film forming composition in which Ar1 in the above formula (2) is anthracene is advantageous not only from the standpoint of etching resistance and solvent solubility, but also from the standpoint of productivity.

[0026] The molecular weight of the (A) polymer is preferably 300 to 1,500.

[0027] 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. In addition, when a resist underlayer film is formed using this composition, a resist underlayer film having excellent film thickness uniformity can be provided.

[0028] The polymer (A) preferably has an end-capping group represented by the following general formula (3). [ka] (In the above formula (3), * is a bond to the methylene group in the above formula (1), d is an integer of 1 to 9, and e is an integer of 0 to 2.)

[0029] A composition for forming a resist underlayer film containing the polymer (A) having the structure represented by the above general formula (3) can improve adhesion to a substrate without deteriorating dry etching resistance.

[0030] It is preferable that the composition for forming a resist underlayer film further contains (C) a blend resin which is a phenol resin or a resin containing a phenolic hydroxy group.

[0031] A composition for forming a resist underlayer film containing such a phenolic resin or a resin containing a phenolic hydroxy group can improve film thickness uniformity while minimizing deterioration of etching resistance after high-temperature treatment in a nitrogen atmosphere.

[0032] In this case, the molecular weight of the (C) blend resin is more preferably 4,000 to 12,000.

[0033] A resist underlayer film forming composition containing the (C) blend resin having a molecular weight within the above range can achieve good film thickness uniformity after high-temperature treatment in a nitrogen atmosphere without deteriorating embedding ability and / or flatness.

[0034] The amount of the blend resin (C) added is preferably 10 to 100 parts by mass per 100 parts by mass of the polymer (A).

[0035] When the resist underlayer film-forming composition contains 10 to 100 parts by mass of the (C) blend resin relative to 100 parts by mass of the (A) polymer, it is possible to highly achieve both film thickness uniformity after high-temperature treatment in a nitrogen atmosphere and dry etching resistance.

[0036] The (C) blend resin is preferably a resin represented by any one of the following general formulas (C-1), (C-2) and (C-3). [ka] (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.) [ka] (In the above formula (C-2), q is an integer of 0 or 1, and r is an integer of 1 to 6.) [ka] (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.)

[0037] When the (C) blend resin has a structure represented by any one of the above formulas (C-1) to (C-3), it becomes possible to more highly achieve both film thickness uniformity after high-temperature treatment in a nitrogen atmosphere and etching resistance.

[0038] It is preferable that the composition for forming a resist underlayer film further contains (D) a crosslinking agent having a structure represented by the following general formula (4). [ka] 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). [ka] (In the above formula (5), * indicates a bond position.)

[0039] A resist underlayer film-forming composition containing such a crosslinking agent having the structure represented by the general formula (4) can provide a resist underlayer film-forming composition having a higher crosslink density. As a result, a resist underlayer film-forming composition having stronger etching resistance can be provided. In addition, crosslinking before high-temperature treatment under a nitrogen atmosphere can improve the film thickness uniformity during high-temperature treatment.

[0040] It is preferable that the composition for forming a resist underlayer film further contains (E) a flowability promoter having a weight loss rate of less than 30% from 30°C to 190°C and a weight loss rate of 98% or more from 30°C to 350°C.

[0041] The flow promoter (E) contributes to improving the flowability of the composition when it is applied, and is removed from the film after baking at 350° C., so that it is possible to improve the embedding property and / or flatness without deteriorating the etching resistance. In addition, it is possible to suppress the occurrence of defects caused by drying, and it can also contribute to improving the yield in semiconductor manufacturing.

[0042] In this case, it is preferable that the (E) flow promoter contains one or more compounds selected from the group consisting of compounds represented by the following general formulas (i) to (iii). [ka] (In the above formula (i), R1's are each 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 a 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.) [ka] (In the above formula (i-1), * indicates a bond position, and R 10 , R 11 , R 12 , and R 13 Each of W is a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms. 10 and W 11 are each independently a single bond or a carbonyl group. i and j are integers of 0 to 10, and i+j≧1. [ka] (In the above formula (i-2), * indicates a bond position.) [ka] (In the above formula (ii), R2 is each 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 a 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.) [ka] (In the above formula (ii-1), * indicates a bond position, and R 20 , R 21 , R 22 and R 23 are each 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. [ka] (In the above formula (ii-2), * indicates a bond position.) [ka] (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 either an aromatic ring or a divalent group represented by the following general formula (iii-1). W6 and W7 are each a single bond or a 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).) [ka] (In the above formula (iii-1), * indicates a bond position, and W 30 is an organic group having 1 to 4 carbon atoms. [ka] (In the above formula (iii-2), * indicates a bond position.)

[0043] The (A) polymer is imparted with thermal fluidity by the addition of the (E) fluidity promoter containing one or more compounds selected from the general formulas (i) to (iii) above, so that the composition for forming a resist underlayer film has high embedding ability and / or flatness.

[0044] The composition for forming a resist underlayer film further comprises (F) a surfactant, (G) an acid generator, and (H) Plasticizer It is preferable that the composition contains one or more of the above.

[0045] A composition for forming a resist underlayer film containing the above additives provides a composition for forming a resist underlayer film that is more excellent in coatability, etching resistance, embedding ability and / or flatness.

[0046] The present invention also provides a method for forming a pattern on a workpiece substrate, comprising the steps of: (I-1) a step of applying the composition for forming a resist underlayer film of the present invention onto a substrate to be processed to obtain a coating film, and then heat-treating the coating film to form a resist underlayer film; (I-2) forming a resist upper layer film on the resist underlayer film using a photoresist material; (I-3) a step of forming a pattern on the resist upper layer film by pattern-exposing the resist upper layer film and then developing the resist upper layer film with a developer; (I-4) a step of transferring the pattern to the resist underlayer film by dry etching using the resist upper layer film on which the pattern is formed as a mask; and (I-5) A step of processing the substrate to be processed using the resist underlayer film on which the pattern has been formed as a mask to form a pattern on the substrate to be processed. The present invention provides a pattern forming method comprising the steps of:

[0047] By the pattern formation method using the two-layer resist process, a fine pattern can be formed on a workpiece (substrate).

[0048] The present invention also provides a method for forming a pattern on a workpiece substrate, comprising the steps of: (II-1) a step of applying the composition for forming a resist underlayer film of the present invention onto a substrate to be processed to obtain a coating film, and then heat-treating the coating film 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) a step of forming a pattern on the resist upper layer film by pattern-exposing the resist upper layer film and then developing the resist upper layer film with a developer; (II-5) a step of transferring the pattern to the resist intermediate film by dry etching using the resist upper layer film on which the pattern has been formed as a mask; (II-6) a step of transferring a pattern to the resist underlayer film by dry etching using the resist intermediate film to which the pattern has been transferred as a mask; and (II-7) A step of processing the substrate to be processed using the resist underlayer film on which the pattern has been formed as a mask to form a pattern on the substrate to be processed. The present invention provides a pattern forming method comprising the steps of:

[0049] The pattern formation method using the three-layer resist process described above makes it possible to form fine patterns on a workpiece with high precision.

[0050] The present invention also provides a method for forming a pattern on a workpiece substrate, comprising the steps of: (III-1) a step of applying the composition for forming a resist underlayer film of the present invention onto a substrate to be processed to obtain a coating film, and then heat-treating the coating film 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 oxynitride 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 top layer film on the organic thin film using a photoresist material; (III-5) a step of forming a pattern on the resist upper layer film by pattern-exposing the resist upper layer film and then developing the resist upper layer film with a developer; (III-6) a step of transferring a pattern to the organic thin film and the inorganic hard mask intermediate film by dry etching using the resist upper layer film on which the pattern has been formed as a mask; (III-7) a step of transferring a pattern to the resist underlayer film by dry etching using the inorganic hard mask intermediate film to which the pattern has been transferred as a mask; and (III-8) A step of processing the substrate to be processed using the resist underlayer film on which the pattern has been formed as a mask to form a pattern on the substrate to be processed. The present invention provides a pattern forming method comprising the steps of:

[0051] The pattern formation method using the four-layer resist process described above makes it possible to form fine patterns on a workpiece with high precision.

[0052] The substrate to be processed may be a substrate having a structure or steps with a height of 30 nm or more.

[0053] The pattern formation method of the present invention uses the resist underlayer film composition of the present invention, which is capable of forming a resist underlayer film having high embedding ability and / or flatness, and is therefore particularly useful for microfabrication of a substrate having such a structure or step.

[0054] The present invention also provides a method for forming a resist underlayer film that functions as an organic flat film used in the manufacturing process of a semiconductor device, comprising spin-coating a composition for forming a resist underlayer film of the present invention onto a substrate to be processed to obtain a coating film, and curing the coating film by heat-treating it at a temperature of 450° C. or higher and 800° C. or lower for 10 to 600 seconds, thereby forming a resist underlayer film.

[0055] By using such a method, the crosslinking reaction during the formation of the resist underlayer film can be promoted, and mixing with the resist overlayer film can be more effectively suppressed. In addition, by appropriately adjusting the heat treatment temperature, time, and oxygen concentration within the above ranges, the thermal decomposition can be promoted, and a film having excellent dry etching resistance can be formed.

[0056] The present invention also provides a method for forming a resist underlayer film that functions as an organic flat film used in the manufacturing process of a semiconductor device, comprising spin-coating a composition for forming a resist underlayer film of the present invention onto a substrate to be processed to obtain a coating film, and curing the coating film by heat-treating it in an atmosphere with an oxygen concentration of 1% or more and 21% or less to form a resist underlayer film.

[0057] By using such a method, the crosslinking reaction during the formation of the resist underlayer film can be promoted, and mixing with the resist overlayer film can be more effectively suppressed. In addition, by appropriately adjusting the heat treatment temperature, time, and oxygen concentration within the above ranges, the thermal decomposition can be promoted, and a film having excellent dry etching resistance can be formed.

[0058] The present invention also provides a method for forming a resist underlayer film that functions as an organic flat film used in the manufacturing process of a semiconductor device, comprising spin-coating a composition for forming a resist underlayer film of the present invention onto a substrate to be processed to obtain a coating film, and curing the coating film by heat-treating it in an atmosphere with an oxygen concentration of less than 1%, thereby forming a resist underlayer film.

[0059] By using this method, even if the substrate to be processed contains a material that is unstable when heated in an oxygen atmosphere, it is possible to promote the crosslinking reaction during the formation of the resist underlayer film without causing deterioration of the substrate to be processed, thereby enabling the formation of a film with excellent dry etching resistance.

[0060] In this case, the substrate to be processed may be a substrate having a structure or steps with a height of 30 nm or more.

[0061] The resist underlayer film forming method of the present invention uses the resist underlayer film material of the present invention, which is capable of forming a resist underlayer film having high dry etching resistance and at the same time high embedding ability and / or flatness, and is therefore particularly suitable for forming a resist underlayer film on a substrate having such structures or steps. Effect of the Invention

[0062] As described above, the composition for forming a resist underlayer film of the present invention makes it possible to form a resist underlayer film (high carbon film) that has excellent resistance to dry etching during substrate processing.

[0063] Furthermore, the pattern forming method of the present invention makes it possible to form a fine pattern on a workpiece with high precision.

[0064] Furthermore, the method for forming a resist underlayer film of the present invention makes it possible to form a film having excellent dry etching resistance.

[0065] Furthermore, the resist underlayer film forming composition, the pattern forming method, and the resist underlayer film forming method of the present invention are particularly suitable for use in a multilayer resist process including filling and / or planarizing a substrate to be processed having steps and irregularities, and are extremely useful in fine patterning for manufacturing semiconductor devices. In particular, in a fine patterning process using a multilayer resist method in a semiconductor device manufacturing process, even on a substrate to be processed having a portion that is difficult to fill and / or planarize, such as a dense portion of a fine pattern structure with a high aspect ratio, as typified by a DRAM memory that is becoming increasingly finer, it is possible to fill without causing defects such as voids or peeling, and a resist underlayer film with excellent flatness characteristics can be formed. In addition, the in-plane uniformity of the film thickness is not deteriorated, and the film exhibits a superior etching resistance to conventional resist underlayer films, and the effect can be exhibited by heating at a temperature of 450°C to 800°C in an atmosphere with an oxygen concentration of less than 1% by volume. Therefore, a fine pattern can be formed on the substrate to be processed with even greater precision. [Brief description of the drawings]

[0066] [Figure 1] FIG. 1 is an explanatory diagram of an example of the pattern forming method of the present invention (three-layer resist process). [Diagram 2] FIG. 2 is an explanatory diagram of a method for evaluating embedding characteristics. [Diagram 3] FIG. 3 is an explanatory diagram of a method for evaluating flattening characteristics. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0067] As described above, in a fine patterning process using a multilayer resist method, there has been a demand for the development of a composition for forming a resist underlayer film, which is used for forming a resist underlayer film capable of transferring a resist pattern to a substrate to be processed with higher accuracy.

[0068] The present inventors have focused on a method of improving the dry etching resistance of a resist underlayer film during substrate processing by heating, for example, at a temperature of 450°C to 800°C in an atmosphere with an oxygen concentration of less than 1% by volume, and have begun to develop a composition for forming a resist underlayer film that dramatically improves dry etching resistance by the above method, and have conducted intensive research.The present inventors have found that, unlike resist underlayer film materials with excellent heat resistance, in the case of a high-carbon material in which thermal decomposition of the cured film actively occurs upon high-temperature baking, when heated at a temperature of, for example, 450°C to 800°C, decomposition and recombination of carbon bonds occur, and the cured film becomes dense. As a result of further intensive research, the present inventors have found that a polymer having a structure represented by the above general formula (A) consisting only of carbon and hydrogen as a repeating unit, but not containing any repeating unit containing a hydroxyl group as a substituent or any repeating unit containing a heteroaromatic ring, can densify a resist underlayer film when heated at a temperature of 450° C. or higher and 800° C. or lower in an atmosphere having an oxygen concentration of less than 1 vol %, and exhibit extremely superior dry etching resistance compared to conventional resist underlayer films, thereby completing the present invention.

[0069] That is, the present invention provides a composition for forming a resist underlayer film, A polymer (A) having a repeating unit represented by the following general formula (1): (B) Organic solvent Contains The composition for forming a resist underlayer film is characterized in that the molecular weight of the polymer (A) is 300 to 3,000, and the polymer (A) does not contain any repeating unit containing a hydroxyl group as a substituent, nor any repeating unit containing a heteroaromatic ring. [ka] (In the above formula (1), Ar is an unsubstituted divalent aromatic group having 6 to 30 carbon atoms.)

[0070] The present invention will be described in detail below, but the present invention is not limited thereto.

[0071] <Composition for forming resist underlayer film> The composition for forming a resist underlayer film of the present invention is a composition for forming a resist underlayer film comprising: (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 polymer (A) is 300 to 3,000; and the polymer (A) does not contain any repeating unit containing a hydroxyl group as a substituent, nor any repeating unit containing a heteroaromatic ring. [ka] (In the above formula (1), Ar is an unsubstituted divalent aromatic group having 6 to 30 carbon atoms.)

[0072] A composition for forming a resist underlayer film containing a polymer (A) having a repeating unit represented by formula (1) consisting only of carbon and hydrogen, but not containing any repeating unit containing a hydroxyl group as a substituent or any repeating unit containing a heteroaromatic ring, can form a resist underlayer film that is densified when baked at high temperature in a nitrogen atmosphere and exhibits excellent etching resistance.

[0073] The aromatic group Ar is preferably an unsubstituted divalent organic group having 6 to 30 carbon atoms, and more preferably has any one of the following structures (1-a). [ka] (In the above formula (1-a), * indicates the bonding position with the methylene group (CH2) in the general formula (1).)

[0074] The aromatic group Ar is more preferably any one of the above structures (1-a), and is particularly preferably any one of naphthalene, anthracene, phenanthrene, and pyrene from the viewpoints of etching resistance and solvent solubility, and further productivity. From the viewpoint of facilitating dissociation and recombination of carbon bonds during high-temperature treatment in a nitrogen atmosphere and forming an amorphous carbon-like film, the aromatic group Ar is more preferably naphthalene or anthracene, and even more preferably anthracene.

[0075] The molecular weight of the polymer (A) is from 300 to 3,000, preferably from 300 to 2,000, and more preferably from 300 to 1,500.

[0076] If the molecular weight of the polymer (A) is 300 to 3,000, a composition for forming a resist underlayer film having excellent solvent solubility can be obtained, and a resist underlayer film having excellent film thickness uniformity after high-temperature baking in a nitrogen atmosphere can be formed. If the molecular weight is less than 300, a large amount of sublimate is produced during high-temperature treatment, resulting in poor film thickness uniformity. On the other hand, if the molecular weight is more than 3,000, the solvent solubility is poor.

[0077] Furthermore, 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.

[0078] The polymer (A) is preferably a copolymer having two types of repeating units represented by the following general formula (2). [ka] (In the above formula (2), Ar1 is any one of naphthalene, anthracene, phenanthrene, and pyrene, and Ar2 has a structure different from Ar1 and is any one selected from the above formula (1-a). a+b is 100, 30≦a≦99, and 1≦b≦70.)

[0079] In the formula (2), Ar1 is any one of naphthalene, anthracene, phenanthrene, and pyrene, but from the viewpoint of easily promoting dissociation and recombination of carbon bonds during high-temperature treatment in a nitrogen atmosphere and being able to form an amorphous carbon-like film, Ar1 is preferably naphthalene or anthracene, and more preferably anthracene. In addition, in the formula (2), Ar2 has a structure different from Ar1, but when Ar1 is anthracene, from the viewpoints of etching resistance, solvent solubility, and productivity, Ar2 is preferably naphthalene, phenanthrene, or pyrene.

[0080] In the formula (2), the ranges of a and b are 30≦a≦99 and 1≦b≦70, and from the viewpoint of etching resistance and solvent solubility, it is preferable that they are 50≦a≦80 and 20≦b≦50.

[0081] The polymer (A), which is a copolymer having two types of repeating units represented by the above 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).

[0082] [ka] (In the above formula, Ar1 and Ar2 are the same as those in formula (2), and X is a hydroxy group, an alkoxy group having 1 to 4 carbon atoms, or a halogen group.)

[0083] In the formula (2-a) and the formula (2-b), X is a hydroxy group, an alkoxy group having 1 to 4 carbon atoms, or a halogen group, and from the viewpoint of productivity and reactivity, it is preferably a hydroxy group or a methoxy group, and more preferably a hydroxy group. Note that the monomers represented by the formula (2-a) and the formula (2-b) may contain a hydroxy group (hydroxyl group) as X, but since X is eliminated by the polymerization reaction, the polymer having a structure represented by the formula (2), which is the polymerization product of these monomers, does not contain a hydroxyl group in the repeating unit.

[0084] The polymer (A) preferably has an end-capping group represented by the following general formula (3). [ka] (In the above formula (3), * is a bond to the methylene group (CH2) in the above formula (1) or formula (2), d is an integer of 1 to 9, and e is an integer of 0 to 2.)

[0085] In the formula (3), d is an integer of 1 to 9, and e is an integer of 0 to 2, but from the viewpoint of the balance between etching resistance and solvent solubility / substrate adhesion, and further from the viewpoint of productivity, d is preferably 1 or 2, and e is preferably 0 or 1. When it is desired to improve the etching resistance, it is preferable that d is small and e is large, and when it is desired to improve the solvent solubility / substrate adhesion, it is preferable that d is large and e is small.

[0086] Although the polymer (A) may contain the above-mentioned terminal blocking group represented by formula (3) at the terminal, the repeating units constituting the polymer (A) do not contain a hydroxyl group.

[0087] [(A) First method for producing polymer] The polymer (A) having the structure represented by formula (1) as a repeating unit can be obtained, for example, by a polycondensation reaction between an aromatic ring compound or a condensed aromatic ring compound represented by Ar' shown below and formaldehyde. In the following formula, Ar is the same as above, and Ar' is an aromatic ring compound or a condensed aromatic ring compound having an unsubstituted aromatic ring having 6 to 30 carbon atoms. [ka]

[0088] The aromatic ring compounds or condensed aromatic ring compounds used in the polycondensation reaction may be used alone or in combination of two or more kinds, which can be appropriately selected according to the required properties.

[0089] The polycondensation reaction can be carried out in an organic solvent in the presence of an acid catalyst, usually at room temperature or under cooling or heating as necessary. Examples of the acid catalyst that can be used include inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, and heteropolyacids, organic acids such as oxalic acid, trifluoroacetic acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, and trifluoromethanesulfonic acid, and Lewis acids such as aluminum trichloride, aluminum ethoxide, aluminum isopropoxide, boron trifluoride, boron trichloride, boron tribromide, tin tetrachloride, tin tetrabromide, dibutyltin dichloride, dibutyltin dimethoxide, dibutyltin oxide, titanium tetrachloride, titanium tetrabromide, titanium(IV) methoxide, titanium(IV) ethoxide, titanium(IV) isopropoxide, and titanium(IV) oxide.

[0090] Although any of the above-mentioned acid catalysts can be used for synthesis, synthesis using a Lewis acid containing a metal makes it difficult to remove the metal from the polymer, so an organic acid that does not contain a metal is preferred, and trifluoroacetic acid, methanesulfonic acid, benzenesulfonic acid, and p-toluenesulfonic acid are more preferred.

[0091] Examples of the organic solvent used in the polycondensation reaction include alcohols such as methanol, ethanol, isopropyl alcohol, butanol, ethylene glycol, propylene glycol, diethylene glycol, glycerol, ethylene glycol monomethyl ether, and propylene glycol monomethyl ether; ethers such as diethyl ether, dibutyl ether, diethylene glycol diethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, and 1,4-dioxane; chlorine-based solvents such as methylene chloride, chloroform, dichloroethane, and trichloroethylene; hydrocarbons such as hexane, heptane, benzene, toluene, xylene, and cumene; nitriles such as acetonitrile; ketones such as acetone, ethyl methyl ketone, and isobutyl methyl ketone; esters such as ethyl acetate, n-butyl acetate, and propylene glycol methyl ether acetate; and aprotic polar solvents such as dimethyl sulfoxide, N,N-dimethylformamide, and hexamethylphosphoric triamide. These can be used alone or in combination of two or more.

[0092] The reaction method includes a method of charging an aromatic ring compound or a condensed aromatic ring compound, formaldehyde, and an acid catalyst all at once, a method of dispersing or dissolving an aromatic ring compound or a condensed aromatic ring compound and formaldehyde, and then adding an acid catalyst all at once or diluting it with a solvent and adding it dropwise, or a method of dispersing or dissolving an acid catalyst, and then adding an aromatic ring compound or a condensed aromatic ring compound and formaldehyde all at once or diluting it with a solvent and adding it dropwise. After the reaction is completed, the composition for forming an organic film of the present invention may be used as it is, but it may also be recovered by diluting it with an organic solvent and then performing separation and washing to remove unreacted raw materials, acid catalyst, etc. present in the system.

[0093] The organic solvent used in the liquid separation washing is not particularly limited as long as it can dissolve the compound and separates into two layers when mixed with water. Examples of the organic solvent include hydrocarbons such as hexane, heptane, benzene, toluene, and xylene; esters such as ethyl acetate, n-butyl acetate, and propylene glycol methyl ether acetate; ketones such as methyl ethyl ketone, methyl amyl ketone, cyclohexanone, and methyl isobutyl ketone; ethers such as diethyl ether, diisopropyl ether, methyl tert-butyl ether, and ethyl cyclopentyl methyl ether; chlorine-based solvents such as methylene chloride, chloroform, dichloroethane, and trichloroethylene; and mixtures thereof.

[0094] The washing water used in the liquid separation washing may be what is usually called deionized water or ultrapure water. The number of washings may be one or more times, but washing ten or more times does not necessarily provide the effect of washing, so it is preferably about one to five times.

[0095] In order to remove unreacted raw materials or acidic components from the system during separation washing, washing may be performed with a basic aqueous solution. Specific examples of the base contained in the basic aqueous solution include alkali metal hydroxides, alkali metal carbonates, alkaline earth metal hydroxides, alkaline earth metal carbonates, ammonia, and organic ammonium.

[0096] Furthermore, in order to remove unreacted raw materials, metal impurities, or basic components from the system during separation washing, washing may be performed with an acidic aqueous solution. Specific examples of the acid contained in the acidic aqueous solution include inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, and heteropolyacids, and organic acids such as oxalic acid, trifluoroacetic acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, and trifluoromethanesulfonic acid.

[0097] The above-mentioned separation washing with a basic aqueous solution and an acidic aqueous solution may be performed either alone or in combination. From the viewpoint of removing metal impurities, the separation washing is preferably performed in the order of a basic aqueous solution and an acidic aqueous solution.

[0098] After the above-mentioned separation washing with the basic aqueous solution or acidic aqueous solution, washing with neutral water may be performed successively. The number of washings may be one or more times, but is preferably about 1 to 5 times. As the neutral water, the above-mentioned deionized water or ultrapure water may be used. The number of washings may be one or more times, but if the number of washings is too few, the basic components and acidic components may not be removed. Even if washing is performed 10 times or more, the effect of washing alone may not be obtained, so it is preferably about 1 to 5 times.

[0099] Furthermore, the reaction product after separation washing can be recovered as a powder by concentrating the solvent to dryness or crystallizing it under reduced pressure or normal pressure, but it can also be left in a solution state of a moderate concentration in order to improve operability when preparing an organic film-forming composition. The concentration at this time is preferably 0.1 to 50% by mass, more preferably 0.5 to 30% by weight. At such a concentration, the viscosity is unlikely to increase, so that the operability is prevented from being impaired, and the amount of solvent is not excessive, so that it is economical.

[0100] The solvent used in this case is not particularly limited as long as it can dissolve the polymer, and specific examples include ketones such as cyclohexanone and methyl-2-amyl ketone; 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 can be used alone or in combination of two or more.

[0101] [Second method for producing polymer (alternative method 1)] As a second alternative production method, polymer (A) having the structure represented by formula (1) as a repeating unit can be obtained by a polymerization reaction using a raw material represented by Ar-CH2-X, where Ar is the same as above, and X is a hydroxy group, an alkoxy group having 1 to 4 carbon atoms, or a halogen group. [ka]

[0102] The polymerization reaction described above is a polymerization reaction that can obtain a polymer from a single monomer. In the polycondensation reaction of the first production method, a typical polymer is obtained by using two ordinary monomers A and B and undergoing an intermolecular dehydration reaction or the like to obtain a repeating unit derived from the monomers A and B, but the above-mentioned method for producing a polymer makes it possible to synthesize a homopolymer from one monomer. In the present invention, the second production method is preferred from the viewpoint of productivity.

[0103] [First method for producing polymers: Monomers alternately form repeating units] [ka]

[0104] [Second method for producing polymer (alternative method 1): homopolymer of monomer A only] [ka]

[0105] In the polymer synthesis reaction method shown above, for example, when two types of monomers (Ar and Ar'') with different Ar are used, a random polymer without a specific repeating unit can be synthesized by feeding the monomers all at once. Also, after synthesizing a polymer with a monomer having Ar in the first stage, a monomer having Ar'' can be further fed in two stages to synthesize a polymer with a block structure. These synthesis methods can be appropriately selected depending on the required performance, etc.

[0106] [Two types of monomer: random type (batch charge)] [ka]

[0107] [Two types of monomer: block type (two-step preparation)] [ka]

[0108] The polymer having two types of repeating units represented by formula (2) obtained by the above synthesis method is preferable because it can provide a composition for forming a resist underlayer film that exhibits excellent solvent solubility compared to the polymer obtained by the third synthesis method (alternative method 2) described below. It is presumed that the excellent solvent solubility is due to the random inclusion of two different types of Ar and Ar''.

[0109] [Polymer manufacturing method (alternative method 2)] [ka] (Ar', Ar1 and Ar2 are the same as above, and X is a hydroxy group, an alkoxy group having 1 to 4 carbon atoms, or a halogen group.)

[0110] The polymer obtained by the third manufacturing method (alternative method 2) is a polymer having repeating units in which aromatic ring compounds or condensed aromatic ring compounds and X-CH2-Ar2-CH2-X are arranged alternately. This synthesis method can also synthesize homopolymers if raw materials with the same structure are used for Ar1 and Ar2, but it has the disadvantage 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 as a result, and there is a risk that the dry etching resistance will be deteriorated.

[0111] [Monomers A and B alternate to form repeating units] [ka]

[0112] Furthermore, in the case of the above-mentioned polymer synthesis reaction method (Second Production Method: Alternative Method 1), the aromatic component Ar x (Ar x (has no reactive unit) can be introduced as a terminal blocking unit. The method of introducing these terminal blocking groups can be appropriately selected depending on the reaction rate, etc. In conventional polymerization methods, only both ends can be introduced due to reactivity, but when this polymerization method is used, one molecule of terminal blocking unit can be introduced per polymer molecule. Therefore, when a polar group such as a hydroxyl group is introduced to adjust the film forming property and adhesion when used as a resist underlayer film material by terminal blocking, the performance can be improved with a minimum amount of introduction, which is advantageous in terms of etching resistance. On the other hand, when a polar group such as a hydroxyl group is included in the repeating unit structure of the polymer, many heteroatoms are contained, so even if the carbon bond dissociates and recombines due to high-temperature treatment, many heteroatoms remain, and there is a risk that the dry etching resistance will be deteriorated.

[0113] [End-capping: introduced during the reaction] [ka]

[0114] [End sealing: batch loading] [ka]

[0115] Aromatic component Ar x Examples of the organic group include the following, and these aromatic rings may have a substituent such as a vinyl group, an ethynyl group, an ethynylphenyl group, an allyl group, a propargyl group, an aryl group, an allyloxy group, a propargyloxy group, 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.

[0116] [ka]

[0117] [ka]

[0118] [ka]

[0119] The polymer synthesis reaction shown in the second production method (alternative method 1) can be produced by the same reaction method and recovery method as the first production method, except that a monomer represented by Ar-CH2-X is used. The same is true for the third production method (alternative method 2).

[0120] <(B) Organic solvent> The (B) organic solvent that can be used in the composition for forming a resist underlayer film of the present invention is not particularly limited as long as it can dissolve the above-mentioned (A) polymer and, if contained, the later-described (C) blend resin, (D) crosslinking agent, (E) flow promoter, (F) surfactant, (G) acid generator, (H) plasticizer, other additives, and the like.

[0121] Specifically, for example, the organic solvents described in paragraphs

[0091] to

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

[0122] The amount of the organic solvent added is preferably within a range from 200 to 10,000 parts, and more preferably from 250 to 5,000 parts, based on 100 parts by mass of the polymer (A).

[0123] <(C) Blended resin> The composition for forming a resist underlayer film of the present invention preferably further contains (C) a blend resin which is a phenol resin or a resin containing a phenolic hydroxy group.

[0124] When the composition for forming a resist underlayer film contains the above-mentioned (C) blend resin having excellent thermosetting properties, the film thickness uniformity after high-temperature baking in a nitrogen atmosphere can be made more excellent.

[0125] The molecular weight of the (C) blend resin is preferably 4,000 to 12,000. From the viewpoint of embedding ability and / or flatness and film thickness uniformity, the molecular weight of the (C) blend resin is preferably 6,000 to 10,000, and more preferably 7,000 to 9,000. When the molecular weight is 4,000 or more, the effect of improving the film thickness uniformity of the resist underlayer film can be sufficiently obtained, and when the molecular weight is 12,000 or less, the embedding ability and / or flatness of the composition for forming a resist underlayer film can be sufficiently realized.

[0126] The amount of the (C) blend resin added is preferably 10 to 100 parts by mass relative to 100 parts by mass of the (A) polymer. From the viewpoint of the etching resistance and film thickness uniformity of the resist underlayer film after high-temperature treatment in a nitrogen atmosphere, the amount of the (C) blend resin added is preferably 20 to 80 parts by mass, more preferably 40 to 60 parts by mass, relative to 100 parts by mass of the (A) polymer.

[0127] The (C) blend resin is preferably a resin represented by any one of the following general formulas (C-1), (C-2) and (C-3).

[0128] [ka] (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.) [ka] (In the above formula (C-2), q is an integer of 0 or 1, and r is an integer of 1 to 6.) [ka] (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.)

[0129] In the above formula (C-1), R is preferably a structure represented by the following formula (C-1a).

[0130] [ka] (In the above formula (C-1a), * indicates the bond position.)

[0131] 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.

[0132] More specific examples of the compound represented by the above formula (C-1) include, but are not limited to, the following.

[0133] [ka]

[0134] In the above formula (C-2), q is preferably 1, r is preferably 1 to 3, and r is more preferably 2 to 3.

[0135] More specific examples of the compound represented by the above formula (C-2) include, but are not limited to, the following.

[0136] [ka]

[0137] In the above formula (C-3), s is preferably 1, t is preferably 1 to 3, and more preferably 2 to 3, and u is preferably 1.

[0138] More specific examples of the compound represented by the above formula (C-3) include, but are not limited to, the following. [ka]

[0139] <(D) Crosslinking agent> The composition for forming a resist underlayer film of the present invention preferably further contains (D) a crosslinking agent having a structure represented by the following general formula (4). [ka] 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). [ka] (In the above formula (5), * indicates a bond position.)

[0140] In the formula (4), Ar3 and Ar4 each represent 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), but from the viewpoint of availability of raw materials, W is preferably an unsubstituted benzene ring, and R A is preferably a hydrogen atom or an n-butyl group.

[0141] The ratio Mw / Mn (i.e., dispersity) of the weight average molecular weight Mw to the number average molecular weight Mn in terms of polystyrene as determined by gel permeation chromatography of the crosslinking agent represented by the above general formula (4) is preferably 1.00≦Mw / Mn≦1.25.

[0142] If the dispersity is within the above range, the thermal fluidity of the composition for forming a resist underlayer film can be sufficient, and when the composition for forming a resist underlayer film is blended, it is possible to fully embed the fine structure formed on the substrate, and further, it is possible to form a resist underlayer film that makes the entire substrate flat. By definition, if it is a monomolecular compound, Mw / Mn is 1.00, but due to the convenience of GPC separation, the measured value may exceed 1.00. In general, unless a special polymerization method is used, it is extremely difficult for a polymer having a repeating unit to approach Mw / Mn=1.00, and it has a Mw distribution, and Mw / Mn is a value exceeding 1. In the present invention, 1.00≦Mw / Mn≦1.25 is defined as an index indicating monomolecularity in order to distinguish between monomolecular compounds and polymers.

[0143] 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, relative to 100 parts by mass of the polymer (A).

[0144] <(E) Flow enhancer> It is preferable that the composition for forming a resist underlayer film of the present invention further contains (E) a flowability promoter whose weight loss rate from 30°C to 190°C is less than 30% and whose weight loss rate from 30°C to 350°C is 98% or more.

[0145] A flowability promoter having a weight loss rate of less than 30% from 30° C. to 190° C. and a weight loss rate of 98% or more from 30° C. to 350° C. is preferred because evaporation during heat treatment is suppressed, thereby maintaining a low viscosity sufficiently, the flowability promoter is excellent in thermal fluidity, and little flowability promoter remains in the resist underlayer film after baking. In this specification, the weight loss rate is based on a value determined by TG (thermogravimetry) measurement using a differential thermobalance.

[0146] The upper limit of the temperature range in which the weight loss rate of the (E) fluidity promoter is less than 30% is more preferably 210° C., and even more preferably 230° C. By setting the temperature range in which the weight loss rate of the (E) fluidity promoter is less than 30% within the above temperature range, the embeddability and / or flatness can be further improved.

[0147] The temperature at which the weight loss rate of the (E) fluidity promoter is 98% or more is more preferably 330° C., and particularly preferably 310° C. By setting the temperature at which the weight loss rate of the fluidity promoter is 98% or more within the above temperature range, it is possible to further reduce the amount of fluidity promoter remaining in the resist underlayer film after baking.

[0148] By incorporating the above-mentioned (E) flowability promoter, the thermal flowability of the composition for forming a resist underlayer film is improved from the start of heat treatment to curing by crosslinking reaction, so that the composition can exhibit better embedding properties and / or better flatness. Meanwhile, the (E) flowability promoter is reduced by evaporation or the like during heat treatment, so that the etching resistance and optical properties are not impaired.

[0149] More preferred embodiments of the above (E) flow promoter include one or more compounds selected from the group consisting of compounds represented by the following general formulas (i) to (iii). [ka] (In the above formula (i), R1's are each 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 a 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.) [ka] (In the above formula (i-1), * indicates a bond position, and R 10 , R 11 , R 12 , R13 is a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms. 10 and W 11 are each independently a single bond or a carbonyl group. i and j are integers of 0 to 10, and i+j≧1. [ka] (In the above formula (i-2), * indicates a bond position.) [ka] (In the above formula (ii), R2 is each 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 a 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.) [ka] (In the above formula (ii-1), * indicates a bond position, and R 20 , R 21 , R 22 and R 23 are each 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. [ka] (In the above formula (ii-2), * indicates a bond position.) [ka] (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 either an aromatic ring or a divalent group represented by the following general formula (iii-1). W6 and W7 are each a single bond or a 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).) [ka] (In the above formula (iii-1), * indicates a bond position, and W 30 is an organic group having 1 to 4 carbon atoms. [ka] (In the above formula (iii-2), * indicates a bond position.)

[0150] In the above general formula (i), R1's are each independently a hydrogen atom, a hydroxyl group, or an optionally substituted organic group having 1 to 10 carbon atoms.

[0151] Here, in the present invention, the term "organic group" means a group containing at least one carbon, and may further contain hydrogen, and, unless otherwise specified, may also contain nitrogen, oxygen, sulfur, silicon, halogen atoms, etc.

[0152] R1 may be a single group or a mixture of multiple groups. More specifically, R1 may be exemplified by hydrogen atom, hydroxyl group, methyl group, ethyl group, vinyl group, 2,2,2-trifluoroethyl group, propyl group, isopropyl group, allyl group, butyl group, s-butyl group, t-butyl group, isobutyl group, pentyl group, cyclopentyl group, hexyl group, cyclohexyl group, cyclohexenyl group, decyl group, methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, s-butoxy group, t-butyl group, butoxy group, norbornyl group, adamantyl group, phenyl group, toluyl group, xylyl group, naphthyl group, benzyl group, 2-furanyl group, and 2-tetrahydrofuranyl group. Among these, R1 is more preferably a hydrogen atom.

[0153] W1 is a phenylene group or a divalent group represented by the above general formula (i-1). W2 and W3 are a single bond or a divalent group represented by the above general formula (i-2). W2 and W3 are each a single bond or a divalent group represented by the following general formula (i-2). h is an integer of 0 to 10, and g is each independently an integer of 1 to 5.

[0154] In the above formula (i-1), R 10 , R 11 , R 12 and R 13 More specifically, R is a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms. More specifically, R is 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 s-butyl group, a t-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 s-butoxy group, a t-butyl group, a butoxy group, a norbornyl group, an adamantyl group, a phenyl group, a toluyl group, a xylyl group, a naphthyl group, a benzyl group, a 2-furanyl group, or a 2-tetrahydrofuranyl group. 10 , R 11 , R 12and R 13 Each of is more preferably a hydrogen atom or a methyl group, and further preferably a hydrogen atom.

[0155] W 10 and W 11 each independently represents a single bond or a carbonyl group, and i and j each represent an integer of 0 to 10, and i+j≧1.

[0156] In the above formula (ii), R2 may be a single group or a mixture of multiple groups.Specific examples of R2 include hydrogen atom, hydroxyl group, methyl group, ethyl group, vinyl group, 2,2,2-trifluoroethyl group, propyl group, isopropyl group, allyl group, butyl group, s-butyl group, t-butyl group, isobutyl group, pentyl group, cyclopentyl group, hexyl group, cyclohexyl group, cyclohexenyl group, decyl group, methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, s-butoxy group, t-butyl group, butoxy group, norbornyl group, adamantyl group, phenyl group, toluyl group, xylyl group, naphthyl group, benzyl group, 2-furanyl group, and 2-tetrahydrofuranyl group.Among these, R2 is more preferably a hydrogen atom.

[0157] 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.

[0158] In the above formula (ii-1), R 20 , R 21 , R 22 , and R 23More specifically, examples of R include a hydrogen atom, a hydroxy 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 s-butyl group, a t-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 s-butoxy group, a t-butyl group, a butoxy group, a norbornyl group, an adamantyl group, a phenyl group, a toluyl group, a xylyl group, a naphthyl group, a benzyl group, a 2-furanyl group, and a 2-tetrahydrofuranyl group. 20 , R 21 , R 22 , and R 23 Each of is more preferably a hydrogen atom or a methyl group, and further preferably a hydrogen atom.

[0159] In the above formula (ii-1), m and n are integers of 0 to 10, and m+n≧1.

[0160] 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, examples of the hydrogen atom include 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 s-butyl group, a t-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 s-butoxy group, a t-butyl group, a butoxy group, a norbornyl group, an adamantyl group, a phenyl group, a toluyl group, a xylyl group, a naphthyl group, a benzyl group, a 2-furanyl group, and a 2-tetrahydrofuranyl group. Among these, it is more preferable that R3 and R4 are each a hydrogen atom.

[0161] 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 containing either an aromatic ring or a divalent group represented by the above general formula (iii-1). Examples of the organic group having 1 to 10 carbon atoms include the groups listed above for R3 and R4.

[0162] In the above formula (iii), W6 and W7 are each a single bond or a divalent group represented by any of the following general formulas (iii-2), and at least one of them is a divalent group represented by any of (iii-2).

[0163] In the above formula (iii-1), W 30 is an organic group having 1 to 4 carbon atoms. More specifically, examples thereof include a methylene group, an ethylene group, a propylene group, a butylene group, a trimethylene group, and a tetramethylene group. Among these, W 30 More preferably, is an ethylene group.

[0164] More specific examples of the compound represented by the above general formula (i) include, but are not limited to, the following.

[0165] [ka]

[0166] More specific examples of the compound represented by the above general formula (ii) include, but are not limited to, the following.

[0167] [ka]

[0168] More specific examples of the compound represented by the above general formula (iii) include, but are not limited to, the following.

[0169] [ka]

[0170]

[0113] In consideration of the film-forming properties of the composition for forming a resist underlayer film, as well as the embedding properties and / or flatness of the substrate, the flowability promoter (E) used in the composition for forming a resist underlayer film of the present invention is preferably an aromatic-containing compound having a benzyl group or a benzoyl group, and particularly preferably an aromatic-containing compound such as the following:

[0171] (Ei) (Poly)ethylene glycol dibenzoate (E-ii) (Poly)ethylene glycol dibenzyl ether (E-iii) (Poly)propylene glycol dibenzyl ether (E-iv) (Poly)butylene glycol dibenzyl ether (Ev) Dibenzyl linear aliphatic dicarboxylate (E-vi) (Poly)ethylene glycol monobenzyl ether (E-vii) (Poly)phenyl ethers

[0172] [ka]

[0173] In the above formula, n is an integer that results in a molecular weight in the range of 500 or less, and is only applicable within this formula.

[0174] The (E) fluidity promoter used in the composition for forming a resist underlayer film of the present invention has a structure having both a hydrophobic portion consisting of an aromatic ring and a hydrophilic portion (e.g., consisting of the following (iii-1) structure), and therefore has excellent compatibility with the (A) polymer, the (B) organic solvent, and other additives, and can improve the fluidity of the composition without impairing the film-forming properties or storage stability.

[0175] [ka] (In the formula, * indicates a bond position, and W30 is an organic group having 1 to 4 carbon atoms.

[0176] The blending amount of the (E) fluidity promoter is preferably 5 to 100 parts by mass, more preferably 10 to 50 parts by mass, based on 100 parts by mass of the polymer. When the blending amount of the fluidity promoter is 10% by mass or more, the fluidity of the composition for forming the resist underlayer film is 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, it may adversely affect the film formability and dry etching resistance of the obtained coating film.

[0177] As the (E) flow promoter, the above aromatic-containing compounds may be used alone or in combination of two or more.

[0178] <Other ingredients> [Other crosslinking agents] In addition, in addition to the crosslinking agent (D) having the structure of the general formula (4), a general crosslinking agent can be added to the resist underlayer film forming composition of the present invention. The crosslinking agent used is not particularly limited, and various known crosslinking agents can be widely used. Examples include methylol 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. When a crosslinking agent is added, the amount of the crosslinking agent added is preferably 1 to 50 parts, more preferably 5 to 30 parts, based on 100 parts by mass of the polymer (A).

[0179] Specific examples of the melamine-based crosslinking agent include hexamethoxymethylated melamine, hexabutoxymethylated melamine, alkoxy- and / or hydroxy-substituted products thereof, and partial self-condensates thereof.

[0180] Specific examples of glycoluril crosslinking agents include tetramethoxymethylated glycoluril, tetrabutoxymethylated glycoluril, alkoxy and / or hydroxy substituted products thereof, and partial self-condensates thereof.

[0181] Specific examples of benzoguanamine-based crosslinking agents include tetramethoxymethylated benzoguanamine, tetrabutoxymethylated benzoguanamine, alkoxy- and / or hydroxy-substituted products thereof, and partial self-condensates thereof.

[0182] Specific examples of the urea-based crosslinking agent include dimethoxymethylated dimethoxyethyleneurea, its alkoxy and / or hydroxy substituted derivatives, and partial self-condensates thereof.

[0183] A specific example of the β-hydroxyalkylamide crosslinking agent is N,N,N',N'-tetra(2-hydroxyethyl)adipic acid amide. A specific example of the isocyanurate crosslinking agent is triglycidyl isocyanurate or triallyl isocyanurate.

[0184] Specific examples of the aziridine crosslinking agent include 4,4'-bis(ethyleneiminocarbonylamino)diphenylmethane and 2,2-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate].

[0185] Specific examples of the oxazoline-based crosslinking agent include 2,2'-isopropylidenebis(4-benzyl-2-oxazoline), 2,2'-isopropylidenebis(4-phenyl-2-oxazoline), 2,2'-methylenebis4,5-diphenyl-2-oxazoline, 2,2'-methylenebis-4-phenyl-2-oxazoline, 2,2'-methylenebis-4-tertbutyl-2-oxazoline, 2,2'-bis(2-oxazoline), 1,3-phenylenebis(2-oxazoline), 1,4-phenylenebis(2-oxazoline), and 2-isopropenyloxazoline copolymer.

[0186] Specific examples of epoxy crosslinking agents include diglycidyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,4-cyclohexanedimethanol diglycidyl ether, poly(glycidyl methacrylate), trimethylolethane triglycidyl ether, trimethylolpropane triglycidyl ether, and pentaerythritol tetraglycidyl ether.

[0187] Specific examples of polynuclear phenol-based crosslinking agents include compounds represented by the following general formula (XL-1).

[0188] [ka] (In the formula, Q is a single bond or a q c R is a 4-valent hydrocarbon group. 3c is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. c is an integer between 1 and 5.)

[0189] Q is a single bond or a carbon number of 1 to 20 c It is a q-valent hydrocarbon group. c is an integer of 1 to 5, and more preferably 2 or 3. Specific examples of Q include methane, ethane, propane, butane, isobutane, pentane, cyclopentane, hexane, cyclohexane, methylpentane, methylcyclohexane, dimethylcyclohexane, trimethylcyclohexane, benzene, toluene, xylene, ethylbenzene, ethylisopropylbenzene, diisopropylbenzene, methylnaphthalene, ethylnaphthalene, and eicosane. c Examples of such groups include groups in which one hydrogen atom has been removed. 3cis a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. Specific examples of the alkyl group having 1 to 20 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a pentyl group, an isopentyl group, a hexyl group, an octyl group, an ethylhexyl group, a decyl group, and an eicosanyl group. 3c is preferably a hydrogen atom or a methyl group.

[0190] Specific examples of the compound represented by the above general formula (XL-1) include the following compounds. Among these, from the viewpoint of improving the curability and thickness uniformity of the organic film, hexamethoxymethylated products of triphenolmethane, triphenolethane, 1,1,1-tris(4-hydroxyphenyl)ethane, and tris(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene are preferred. 3c is the same as above.

[0191] [ka]

[0192] [ka]

[0193] [(F) Surfactant] A surfactant can be added to the resist underlayer film forming composition of the present invention in order to improve the coating property in spin coating. For example, the surfactants described in

[0142] to

[0147] of JP2009-269953A can be used. When a surfactant is added, the amount of the surfactant added is preferably 0.01 to 10 parts, more preferably 0.05 to 5 parts, based on 100 parts by mass of the (A) polymer.

[0194] [(G) Acid generator] In the resist underlayer film forming composition of the present invention, an acid generator can be added to further promote the curing reaction. The acid generator may be one that generates an acid by thermal decomposition or one that generates an acid by light irradiation, and any of them can be added. Specifically, the materials described in paragraphs

[0061] to

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

[0195] The acid generator may be used alone or in combination of two or more. When an acid generator is added, the amount of the acid generator is preferably 0.05 to 50 parts, more preferably 0.1 to 10 parts, based on 100 parts by mass of the polymer (A).

[0196] [(H) Plasticizer] In addition, a plasticizer can be added to the resist underlayer film forming composition of the present invention in order to further improve embedding property and / or flatness. The plasticizer is not particularly limited, and various known plasticizers can be widely used. Examples include low molecular weight compounds such as phthalates, adipic esters, phosphates, trimellitates, and citrates, polyethers, polyesters, and polymers such as the polyacetal polymers described in JP-A-2013-253227. When a plasticizer is added, the amount of the plasticizer is preferably 1 to 100 parts, more preferably 5 to 30 parts, based on 100 parts by mass of the polymer (A).

[0197] In addition, in the composition for forming a resist underlayer film of the present invention, as an additive for imparting embedding ability and / or flatness in the same manner as a plasticizer, for example, a liquid additive having a polyethylene glycol or polypropylene glycol structure, or a thermally decomposable 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. This thermally decomposable polymer preferably contains a repeating unit having an acetal structure represented by the following general formula (DP1) or (DP1a).

[0198] [ka] (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.)

[0199] [ka] (In the formula, R 6a is an alkyl group having 1 to 4 carbon atoms. a is a saturated or unsaturated divalent hydrocarbon group having 4 to 10 carbon atoms, which may have an ether bond; and n represents the average number of repeating units and is 3 to 500.

[0200] <Pattern Forming Method Using the Composition for Forming Resist Underlayer Film>

[0201] <Pattern Forming Method Using the Composition for Forming Resist Underlayer Film> The present invention also provides a method for forming a pattern on a workpiece substrate, comprising the steps of: (I-1) a step of applying the composition for forming a resist underlayer film described above onto a substrate to be processed to obtain a coating film, and then heat-treating the coating film to form a resist underlayer film; (I-2) forming a resist upper layer film on the resist underlayer film using a photoresist material; (I-3) a step of forming a pattern on the resist upper layer film by pattern-exposing the resist upper layer film and then developing the resist upper layer film with a developer; (I-4) a step of transferring the pattern to the resist underlayer film by dry etching using the resist upper layer film on which the pattern is formed as a mask; and (I-5) A step of processing the substrate to be processed using the resist underlayer film on which the pattern has been formed as a mask to form a pattern on the substrate to be processed. The present invention provides a pattern forming method comprising the steps of:

[0202] By the pattern formation method using the two-layer resist process, a fine pattern can be formed on a workpiece (substrate).

[0203] The present invention also provides a method for forming a pattern on a workpiece substrate, comprising the steps of: (II-1) a step of applying the composition for forming a resist underlayer film described above onto a substrate to be processed to obtain a coating film, and then heat-treating the coating film 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) a step of forming a pattern on the resist upper layer film by pattern-exposing the resist upper layer film and then developing the resist upper layer film with a developer; (II-5) a step of transferring the pattern to the resist intermediate film by dry etching using the resist upper layer film on which the pattern has been formed as a mask; (II-6) a step of transferring a pattern to the resist underlayer film by dry etching using the resist intermediate film to which the pattern has been transferred as a mask; and (II-7) A step of processing the substrate to be processed using the resist underlayer film on which the pattern has been formed as a mask to form a pattern on the substrate to be processed. The present invention provides a pattern forming method comprising the steps of:

[0204] The pattern formation method using the three-layer resist process described above makes it possible to form fine patterns on a workpiece with high precision.

[0205] An example of a pattern forming method by a three-layer resist process will be described with reference to FIG. 1. First, a laminate shown in FIG. 1(A) is formed. Specifically, a resist underlayer film forming composition of the present invention is applied to a workpiece layer 2 of a workpiece substrate 1A including a support substrate 1 and a workpiece layer 2 formed thereon to obtain a coating film, and the coating film is heat-treated to form a resist underlayer film 3. Next, a resist intermediate film 4 is formed on the resist underlayer film 3 using a resist intermediate film material. Next, a resist upper layer film 5 is formed on the resist intermediate film 4 using a photoresist material. Subsequently, as shown in FIG. 1(B), an exposed portion 6 is formed in the resist upper layer film 5 by pattern exposure. Next, the exposed portion 6 is developed with a developer to form a resist upper layer film pattern 5a on the resist upper layer film 5 as shown in FIG. 1(C). Next, a silicon-containing resist intermediate film pattern 4a is transferred to the resist intermediate film 4 by dry etching using the resist upper layer film 5 on which the pattern 5a is formed as a mask, as shown in FIG. 1(D). Next, the resist underlayer film pattern 3a is transferred to the resist underlayer film 3 by dry etching using the resist intermediate film 4 to which the pattern 4a has been transferred as a mask, as shown in Fig. 1(E). Then, the processable layer 2 of the processable substrate 1A is processed using the resist underlayer film 3 to which the pattern 3a has been formed as a mask, to form a pattern 2a on the processable substrate 1 as shown in Fig. 1(F).

[0206] Since the silicon-containing resist intermediate film in the above three-layer resist process exhibits resistance to etching by oxygen-based gas, it is preferable that the dry etching of the resist underlayer film in the above three-layer resist process is performed using the silicon-containing resist intermediate film as a mask, using an etching gas mainly composed of oxygen-based gas.

[0207] As the silicon-containing resist intermediate film in the above three-layer resist process, a polysiloxane-based intermediate film is also preferably used. By imparting an anti-reflection effect to the silicon-containing resist intermediate film, reflection can be suppressed. In particular, for 193 nm exposure, if a material containing many aromatic groups and having high etching selectivity with the substrate is used as the organic film, the k value becomes high and the substrate reflection becomes high, but by imparting absorption to the silicon-containing resist intermediate film to obtain an appropriate k value, it becomes possible to suppress reflection, and the substrate reflection can be reduced to 0.5% or less. As the silicon-containing resist intermediate film having an anti-reflection effect, anthracene is preferably used for 248 nm and 157 nm exposure, and polysiloxane with a pendant light-absorbing group having a phenyl group or a silicon-silicon bond and crosslinked by acid or heat is preferably used for 193 nm exposure.

[0208] In addition, the present invention provides a method for forming a pattern by a four-layer resist process using the composition for forming a resist underlayer film of the present invention, which is a method for forming a pattern on a substrate to be processed, comprising the steps of: (III-1) a step of applying the composition for forming a resist underlayer film of the present invention onto a substrate to be processed to obtain a coating film, and then heat-treating the coating film 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 oxynitride 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 top layer film on the organic thin film using a photoresist material; (III-5) a step of forming a pattern on the resist upper layer film by pattern-exposing the resist upper layer film and then developing the resist upper layer film with a developer; (III-6) a step of transferring a pattern to the organic thin film and the inorganic hard mask intermediate film by dry etching using the resist upper layer film on which the pattern has been formed as a mask; (III-7) a step of transferring a pattern to the resist underlayer film by dry etching using the inorganic hard mask intermediate film to which the pattern has been transferred as a mask; and (III-8) A step of processing the substrate to be processed using the resist underlayer film on which the pattern has been formed as a mask to form a pattern on the substrate to be processed. The present invention provides a pattern forming method comprising the steps of:

[0209] Alternatively, an inorganic hard mask may be formed instead of a silicon-containing resist underlayer film. In this case, at least a resist underlayer film is formed on a workpiece using the composition for forming a resist underlayer film of the present invention, an inorganic hard mask selected from a silicon oxide film, a silicon nitride film, and a silicon oxynitride film is formed on the resist underlayer film, a resist upper layer film is formed on the inorganic hard mask using a photoresist composition, a circuit pattern is formed on the resist upper layer film, the inorganic hard mask is etched using the resist upper layer film on which the pattern has been formed as a mask, the resist underlayer film is etched using the inorganic hard mask on which the pattern has been formed as a mask, and the workpiece is etched using the resist underlayer film on which the pattern has been formed as a mask to form a pattern on the workpiece, thereby forming a semiconductor device circuit pattern on the substrate.

[0210] As described above, when an inorganic hard mask is formed on a resist underlayer film, a silicon oxide film, a silicon nitride film, and a silicon oxide nitride film (SiON film) can be formed by a CVD method, an ALD method, or the like. For example, methods for forming a silicon nitride film are described in JP-A-2002-334869 and WO-A-2004 / 066377. The thickness of the inorganic hard mask is preferably 5 to 200 nm, more preferably 10 to 100 nm. In addition, as the inorganic hard mask, a SiON film, which has a high effect as an anti-reflection film, is most preferably used. Since the substrate temperature during the formation of the SiON film is 300 to 500° C., the resist underlayer film needs to withstand a temperature of 300 to 500° C. The composition for forming the resist underlayer film used in the present invention has high heat resistance and can withstand high temperatures of 300 to 500° C., so that it is possible to combine an inorganic hard mask formed by a CVD method or an ALD method with a resist underlayer film formed by a spin coating method.

[0211] As described above, a photoresist film may be formed on the inorganic hard mask as a resist top layer, but an organic anti-reflective coating (BARC) or adhesion film may be formed on the inorganic hard mask by spin coating, and a photoresist film may be formed on top of that. In particular, when a SiON film is used as the inorganic hard mask, the two-layer anti-reflective coating of the SiON film and the BARC makes it possible to suppress reflection even in immersion exposure with a high NA exceeding 1.0. Another advantage of forming the BARC is that it has the effect of reducing the tailing of the photoresist pattern directly above the SiON film.

[0212] In the above pattern forming method, the resist upper layer film may be either positive or negative, and may be the same as a commonly used photoresist composition. The photoresist composition may contain metal atoms such as Sn, In, Ga, Ge, Al, Ce, La, Cs, Zr, Hf, Ti, Bi, Sb, and Zn. When forming the resist upper layer film using the above photoresist composition, it may be formed by spin coating or deposition processing using CVD or ALD.

[0213] When forming a photoresist composition by spin coating, the resist is prebaked after coating, preferably at 60 to 180° C. for 10 to 300 seconds. Thereafter, exposure is performed according to a conventional method, followed by post-exposure baking (PEB) and development to obtain a resist pattern. The thickness of the resist top layer is not particularly limited, but is preferably 10 to 500 nm, particularly preferably 20 to 400 nm.

[0214] When the photoresist composition is formed by deposition processing by CVD or ALD, the resist composition is an EUV photosensitive metal oxide film, and the metal is selected from Sn, Zr, Hf, Ti, Bi, Sb, etc., among which Sn, which has excellent EUV photosensitivity, is preferred. The metal oxide-containing film may be a photosensitive organometallic oxide film such as an organotin oxide (e.g., haloalkyl Sn, alkoxyalkyl Sn, or amidoalkyl Sn). Some specific examples of suitable precursors include trimethyltin chloride, dimethyltin dichloride, methyltin trichloride, tris(dimethylamino)methyltin(IV), and (dimethylamino)trimethyltin(IV).

[0215] Metal oxide films may be deposited by PECVD or PEALD, for example using a Lam Vector® tool, where the Sn oxide precursor is separated from the O precursor / plasma in ALD. The deposition temperature is preferably in the range of 50° C. to 600° C. The deposition pressure is preferably between 100 and 6000 mTorr. The flow rate of the metal oxide-containing film precursor liquid (e.g., organotin oxide precursor) may be 0.01 to 10 cmm and the gas flow rate (CO2, CO, Ar, N2) may be 100 to 10000 sccm. The plasma power may be 200 to 1000 W per 300 mm wafer station using a high frequency plasma (e.g., 13.56 MHz, 27.1 MHz, or higher). The deposition thickness is preferably 100 to 2000 Å.

[0216] Examples of the exposure light include high energy rays with a wavelength of 300 nm or less, specifically, excimer lasers with wavelengths of 248 nm, 193 nm, and 157 nm, soft X-rays with wavelengths of 3 to 20 nm, electron beams, and X-rays.

[0217] The method for forming the pattern on the resist upper layer film is preferably photolithography with a wavelength of 5 nm or more and 300 nm or less, direct drawing with an electron beam, nanoimprinting, or a combination of these.

[0218] In the pattern forming method, the development method is preferably alkaline development or development using an organic solvent.

[0219] Next, etching is performed using the obtained resist pattern as a mask. In the three-layer resist process, etching of the silicon-containing resist intermediate film and the inorganic hard mask is performed using a fluorocarbon-based gas as a mask for the upper resist pattern. This forms a silicon-containing resist intermediate film pattern and an inorganic hard mask pattern.

[0220] Next, the resist underlayer film is etched using the silicon-containing resist intermediate film pattern or the inorganic hard mask pattern as a mask. The etching of the resist underlayer film is preferably carried out using an etching gas mainly containing an oxygen-based gas.

[0221] The next etching of the workpiece can also be done by a normal method, for example, if the workpiece is SiO2, SiN, or a silica-based low dielectric constant insulating film, etching is done mainly with fluorocarbon gases. When etching the substrate with fluorocarbon gases, the silicon-containing resist intermediate film pattern in the three-layer resist process is peeled off at the same time as the substrate is processed.

[0222] The resist underlayer film obtained from the composition for forming a resist underlayer film of the present invention is characterized by excellent etching resistance when etching the workpiece.

[0223] The workpiece (substrate) is not particularly limited, and may be a substrate such as Si, α-Si, p-Si, SiO2, SiN, SiON, W, TiN, or Al, or a substrate (support substrate) on which a workpiece layer is formed. As the workpiece layer, various low-k films such as Si, SiO2, SiON, SiN, p-Si, α-Si, W, W-Si, Al, Cu, or Al-Si and their stopper films are used, and may be formed to a thickness of usually 50 to 10,000 nm, particularly 100 to 5,000 nm. When forming a workpiece layer, the substrate and the workpiece layer are made of different materials.

[0224] In the pattern forming method using the resist underlayer film forming composition of the present invention, it is preferable to use a substrate to be processed having a structure or step having a height of 30 nm or more. As described above, the resist underlayer film forming composition of the present invention has excellent filling and / or planarization properties, so that even if the substrate to be processed has a structure or step (unevenness) having a height of 30 nm or more, a flat cured film can be formed. The height of the structure or step of the substrate to be processed is preferably 30 nm or more, more preferably 50 nm or more, and more preferably 100 nm or more. In the method for processing a stepped substrate having a pattern of the above height, the resist underlayer film forming composition of the present invention is formed into a film and filled and / or planarized, so that the thickness of the resist intermediate film and resist top layer film formed thereafter can be made uniform, which is very preferable.

[0225] <Method for forming resist underlayer film> The present invention provides a method for forming a resist underlayer film that functions as an organic flat film used in the manufacturing process of a semiconductor device, comprising spin-coating a composition for forming a resist underlayer film of the present invention onto a substrate to be processed to obtain a coating film, and curing the coating film by heat-treating it at a temperature of 450°C or higher and 800°C or lower for 10 to 600 seconds, thereby forming a resist underlayer film.

[0226] The present invention also provides a method for forming a resist underlayer film that functions as an organic flat film used in the manufacturing process of a semiconductor device, comprising spin-coating the composition for forming a resist underlayer film of the present invention on a substrate to be processed to obtain a coating film, and curing the coating film by heat-treating it in an atmosphere with an oxygen concentration of 1% or more and 21% or less to form a resist underlayer film.

[0227] Alternatively, there is provided a method for forming a resist underlayer film that functions as an organic flat film used in the manufacturing process of a semiconductor device, the method being characterized in that the composition for forming a resist underlayer film of the present invention is spin-coated on a substrate to be processed to obtain a coating film, and the coating film is cured by heat-treating it in an atmosphere with an oxygen concentration of less than 1%, thereby forming a resist underlayer film.

[0228] In the resist underlayer film forming method of the present invention, the resist underlayer film material is coated on a substrate to be processed by using a spin coating method or the like. By using a spin coating method or the like, good embedding properties can be obtained. After spin coating, the organic solvent is evaporated, and a heat treatment (baking) is performed to promote a crosslinking reaction in order to prevent mixing with the resist upper layer film or the resist middle layer film. Baking is preferably performed within a temperature range of 100°C to 800°C, more preferably 300°C to 800°C, and even more preferably 450°C to 800°C. The baking time is preferably 10 seconds to 600 seconds, and even more preferably 10 to 300 seconds. By appropriately adjusting the baking temperature and time within the above ranges, flattening and / or embedding properties suitable for the application, as well as hardening properties such as dry etching resistance and heat resistance, can be obtained. By baking within a temperature range of 450°C to 800°C, particularly excellent dry etching resistance can be obtained. At a baking temperature of 100°C or higher, curing proceeds sufficiently and mixing with the resist upper layer or intermediate layer can be suppressed. At a baking temperature of 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.

[0229] The atmosphere during the heat treatment can be selected as necessary from either an oxygen-containing atmosphere such as air (oxygen concentration 1% to 21%) or an oxygen-free atmosphere such as nitrogen. For example, if the substrate to be processed is susceptible to air oxidation, substrate damage can be suppressed by forming a hardened film by performing heat treatment in an atmosphere with an oxygen concentration of less than 1%.

[0230] In the resist underlayer film forming method using the resist underlayer film forming composition of the present invention, it is preferable to use a substrate to be processed having a structure or step having a height of 30 nm or more. As described above, the resist underlayer film forming composition of the present invention has excellent filling and / or planarization properties, so that even if the substrate to be processed has a structure or step (unevenness) having a height of 30 nm or more, a flat cured film can be formed. The height of the structure or step of the substrate to be processed is preferably 30 nm or more, more preferably 50 nm or more, and more preferably 100 nm or more. In the method for processing a stepped substrate having a pattern of the above height, the resist underlayer film forming composition of the present invention is formed into a film and filled and / or planarized, so that the film thickness of the resist intermediate film and resist top layer film formed thereafter can be made uniform, which is very preferable. EXAMPLES

[0231] The present invention will be described in more detail below with reference to Synthesis Examples, Comparative Synthesis Examples, Examples, and Comparative Examples, but the present invention is not limited thereto. Note that, as for the molecular weight and dispersity, the weight average molecular weight (Mw) and number average molecular weight (Mn) in terms of polystyrene were determined by gel permeation chromatography (GPC) using tetrahydrofuran as an eluent, and the dispersity (Mw / Mn) was determined.

[0232] Synthesis Example (A) Polymer Synthesis The polymers (A1) to (A7) were synthesized using the following compound group b: (b1) to (b6). [ka]

[0233] [Synthesis Example 1] Synthesis of polymer (A1) [ka]

[0234] 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 resulting mixture over 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, after which the insoluble matter was removed by filtration. The collected filtrate was washed six 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 collected. The collected crystals were dried in a vacuum at 70°C to obtain polymer (A1).

[0235] The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the results were as follows: (A1): Mw = 2,710, Mw / Mn = 1.86

[0236] [Synthesis Example 2] Synthesis of polymer (A2) [ka]

[0237] In a nitrogen atmosphere, 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 resulting mixture over 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 matter was removed by filtration. The collected filtrate was washed six 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 collected. The collected crystals were dried in a vacuum at 70°C to obtain polymer (A2).

[0238] The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the results were as follows: (A2): Mw = 2,030, Mw / Mn = 1.56

[0239] [Synthesis Example 3] Synthesis of polymer (A3) [ka]

[0240] In a nitrogen atmosphere, 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 resulting mixture over 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 matter was removed by filtration. The collected filtrate was washed six 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 collected. The collected crystals were dried in a vacuum at 70°C to obtain polymer (A3).

[0241] The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the results were as follows: (A3): Mw=560, Mw / Mn=2.43

[0242] [Synthesis Example 4] Synthesis of polymer (A4) [ka]

[0243] 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 resulting mixture over 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 matter was removed by filtration. The collected filtrate was washed six 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 collected. The collected crystals were dried in a vacuum at 70°C to obtain polymer (A4).

[0244] The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the results were as follows: (A4): Mw=680, Mw / Mn=2.27

[0245] [Synthesis Example 5] Synthesis of polymer (A5) [ka]

[0246] Under a nitrogen atmosphere, 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 resulting mixture over 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 matter was removed by filtration. The collected filtrate was washed six 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 collected. The collected crystals were dried in a vacuum at 70°C to obtain polymer (A5).

[0247] The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the results were as follows: (A5): Mw=720, Mw / Mn=2.13

[0248] [Synthesis Example 6] Synthesis of polymer (A6) [ka] In 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 resulting mixture over 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 matter was removed by filtration. The collected filtrate was washed six 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 collected. The collected crystals were dried in a vacuum at 70°C to obtain polymer (A6).

[0249] The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the results were as follows: (A6): Mw=700, Mw / Mn=1.43

[0250] [Synthesis Example 7] Synthesis of polymer (A7) [ka]

[0251] Under a nitrogen atmosphere, 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, and 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 matter was removed by filtration. The collected filtrate was washed six 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 collected. The collected crystals were dried in a vacuum at 70°C to obtain polymer (A7).

[0252] The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the results were as follows: (A7): Mw=942, Mw / Mn=2.73

[0253] Comparative Synthesis Examples Synthesis of Comparative Polymers and Comparative Compounds The comparative polymers (R2), (R3), (R5), (R7), (R9) and (R11) were synthesized using the following compound group c: (c1) to (c5) and the above compound group b: (b2). [ka]

[0254] [Comparative Synthesis Example 1] Synthesis of Comparative Polymer (R1) [ka]

[0255] In a nitrogen atmosphere, 160.2 g of 1,5-dihydroxynaphthalene, 64.9 g of 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 dropped and 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 six 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 homogenous 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 collected. The collected crystals were dried in a vacuum at 70°C to obtain polymer (R1).

[0256] The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the results were as follows: (R1): Mw = 4,000, Mw / Mn = 3.0

[0257] [Comparative Synthesis Example 2] Synthesis of Comparative Polymer (R2) [ka]

[0258] Under a nitrogen atmosphere, 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 obtain a homogeneous solution at a liquid temperature of 80°C. Next, 18 g of a 20% p-toluenesulfonic acid 2-methoxy-1-propanol solution was slowly added, and the mixture was stirred at a liquid temperature of 110°C for 8 hours. After cooling the mixture 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 the organic layer was 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 polymer (R2).

[0259] The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the results were as follows: (R2): Mw = 3,460, Mw / Mn = 4.60

[0260] [Comparative Synthesis Example 3] Synthesis of Comparative Polymer (R3) [ka]

[0261] The polymer reported in [Synthesis Example 1] of JP 2021-138851 was synthesized. 54.5 g of fluorenol (c2) and 200 g of 1,2-dichloroethane were mixed and heated to 50 ° C. 20.3 g of methanesulfonic acid was slowly dropped and heated and stirred at 70 ° C for 6 hours. After cooling to room temperature, 650 g of toluene was added, washed six 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 homogeneous solution, and 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 collected. The collected crystals were vacuum dried at 70 ° C to obtain polymer (R3).

[0262] The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the results were as follows: (R3): Mw = 2,700, Mw / Mn = 1.39

[0263] [Comparative Synthesis Example 4] Synthesis of Comparative Compound (R4) [ka]

[0264] Under a nitrogen atmosphere, 20.0 g of di-1-naphthylmethanol and 240 ml of dichloroethane were mixed and 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 obtain a homogenous solution, the reaction was carried out in a 60°C oil bath 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 to recover the lower organic phase, which was then washed five times with ultrapure water, after which the organic layer was dried under reduced pressure to recover compound (R4).

[0265] The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the results were as follows: (R4): Mw=280, Mw / Mn=1.01

[0266] [Comparative Synthesis Example 5] Synthesis of Comparative Polymer (R5) [ka]

[0267] In a nitrogen atmosphere, 60.0 g of compound (b2) and 300 g of 1,2-dichloroethane were mixed and uniformly dispersed at an internal temperature of 60°C, and then 74.5 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 6 hours. After the mixture was cooled to room temperature, 400 g of 1,2-dichloroethane was added, and the insoluble matter was removed by filtration. The collected filtrate was washed six 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 collected. The collected crystals were vacuum dried at 70°C to obtain polymer (R5).

[0268] The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the results were as follows: (R5): Mw = 3,150, Mw / Mn = 1.43

[0269] [Comparative Synthesis Example 6] Synthesis of Comparative Polymer (R6) [ka]

[0270] Under a nitrogen atmosphere, 15.6g of 2-phenylphenol, 19.1g of 9-anthracenemethanol, 12.3g of divinylbenzene, 30g of cyclopentyl methyl ether (CPME), and 110g of diethylene glycol dimethyl ether were mixed and stirred at room temperature to uniformly disperse. Then, 1.14g of trifluorosulfonic acid was slowly added, and the mixture was stirred for another 5 minutes to obtain a uniform solution. After that, the reaction was carried out for 4 hours in an oil bath at 140°C while removing the water generated from the reaction system. The reactant was cooled to room temperature, diluted with 250g of CPME, transferred to a separatory funnel, washed four times with ultrapure water, and then the organic layer was dried under reduced pressure. 120g of CPME was added to the residue, and a polymer was crystallized with 500g of hexane. The crystallized crystals were separated by filtration, washed twice with 200g of hexane, and the crystals were collected. The collected crystals were dried in a vacuum at 70°C to obtain polymer (R6).

[0271] The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the results were as follows: (R6): Mw = 1,960, Mw / Mn = 1.57

[0272] [Comparative Synthesis Example 7] Synthesis of Comparative Polymer (R7) [ka]

[0273] In 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 carry out a polymerization reaction. After the reactant was gradually cooled to room temperature, the reactant was put into 40 g of ultrapure water and 400 g of methanol, 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 (first step). The supernatant obtained at this time was removed again and the precipitate was dissolved in 80 g of propylene glycol monomethyl ether acetate (PGMEA) (second step). The first and second steps were considered as one purification step, and this purification step was carried out three times in total. After the purification, the polymer was dissolved in 80 g of propylene glycol monomethyl ether acetate (PGMEA), and the remaining methanol and ultrapure water were removed under reduced pressure to obtain polymer (R7).

[0274] The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the results were as follows: (R7): Mw=3,500, Mw / Mn=1.52

[0275] [Comparative Synthesis Example 8] Synthesis of Comparative Polymer (R8) [ka]

[0276] In a nitrogen atmosphere, 28.3 g of pyrene, 28.8 g of 1-naphthol, 12.1 g of p-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 carry out a polymerization reaction. After the reactants were gradually cooled to room temperature, the reactants were put into 40 g of ultrapure water and 400 g of methanol, vigorously stirred, 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 vigorously stirred with 320 g of methanol and allowed to stand (first step). The supernatant obtained at this time was removed again, and the precipitate was dissolved in 80 g of propylene glycol monomethyl ether acetate (PGMEA) (second step). The first and second steps were considered as one purification step, and this purification step was carried out three times in total. After the purification, the polymer was dissolved in 80 g of propylene glycol monomethyl ether acetate (PGMEA), and the remaining methanol and ultrapure water were removed under reduced pressure to obtain a polymer (R8).

[0277] The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the results were as follows: (R8): Mw=4,000, Mw / Mn=1.75

[0278] [Comparative Synthesis Example 9] Synthesis of Comparative Polymer (R9) [ka]

[0279] 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 carry out a polymerization reaction. The reactant was precipitated in methanol to remove monomers and low molecular weight substances, thereby obtaining a polymer (R9).

[0280] The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the results were as follows: (R9): Mw=2,500, Mw / Mn=2.1

[0281] [Comparative Synthesis Example 10] Synthesis of Comparative Polymer (R10) [ka]

[0282] In a nitrogen atmosphere, 3.5g of indole, 6.0g of pyrene, 1.8g of p-formaldehyde, 0.57g of p-toluenesulfonic acid monohydrate, and 100g of propylene glycol monomethyl ether acetate (PGMEA) were mixed and stirred at 90℃ for 12 hours to carry out a polymerization reaction. After the reactants were gradually cooled to room temperature, the reactants were poured into 300g of pure water and 300g of methanol, vigorously stirred, and then allowed to stand. The supernatant was removed and the precipitate was dissolved in 100g of propylene glycol monomethyl ether acetate (PGMEA), and then vigorously stirred with 300g of methanol and 300g of ultrapure water and allowed to stand (first step). The supernatant obtained at this time was removed again, and the precipitate was dissolved in 80g of propylene glycol monomethyl ether acetate (PGMEA) (second step). The first and second steps were counted as one purification step, and this purification step was repeated three times in total. After the purification step, the polymer was dissolved in 80 g of propylene glycol monomethyl ether acetate (PGMEA), and the remaining methanol and ultrapure water were removed under reduced pressure to obtain polymer (R10).

[0283] The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the results were as follows: (R10): Mw = 2,800, Mw / Mn = 1.51

[0284] [Comparative Synthesis Example 11] Synthesis of Comparative Polymer (R11) [ka]

[0285] Under a nitrogen atmosphere, 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, and 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 matter was removed by filtration. The collected filtrate was washed six 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 collected. The collected crystals were dried in a vacuum at 70°C to obtain polymer (R11).

[0286] The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the results were as follows: (R11): Mw=2,480, Mw / Mn=1.93 minutes

[0287] [Example 1 and Comparative Example 1: Solubility Evaluation] The solubilities of the (A) polymers (A1) to (A7) synthesized above and the comparative polymers (R1) to (R11) were confirmed.

[0288] The solvents used were two organic solvents, propylene glycol monomethyl ether acetate (PGMEA) and cyclohexanone (CyHO), and the solubility was evaluated under three conditions: 70 / 30, 50 / 50, and CyHO only. If the material was completely dissolved to form a homogeneous solution, it was rated as "dissolved," and if it was not completely dissolved and some insoluble matter remained, it was rated as "insoluble."

[0289] The results are shown in Table 1 below.

[0290] [Table 1]

[0291] Examples 1-1 to 1-6 using the polymer for use in the composition for forming a resist underlayer film of the present invention showed 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 tended to worsen as the structure of the condensed aromatic ring became larger, but polymers (A1) to (A6) including polymers (A2) and (A3) were soluble in a mixed solvent of PGMEA / CyHO=50 / 50 and a CyHO solvent. Basically, CyHO is superior in resin solubility, but from the viewpoint of film-forming properties, it is preferable that the amount of PGMEA is larger.

[0292] Among the polymers used in the resist underlayer film forming composition of the present invention, only Example 1-7 was insoluble in the PGMEA / CyHO system. This polymer is a resin similar in structure to polymer (A3) in that the aromatic group represented by Ar in the above general formula (1) is anthracene, but it was synthesized by Alternative Method 2, which has a different synthesis recipe. It is difficult to control the molecular weight in the synthesis by Alternative Method 2, and it is presumed that this is because the molecular weight ended up being larger than that of polymer (A3).

[0293] On the other hand, Comparative Example 1-5, which used a comparative polymer (R5) having a higher molecular weight than the polymer used in the composition for forming a resist underlayer film of the present invention, had insufficient solubility in CyHO. This shows that molecular weight control is important for achieving excellent solvent solubility.

[0294] In addition, Comparative Example 1-11, which used the comparative polymer (R11), which is a block copolymer having a repeating unit containing a substituted aromatic group, unlike the polymer used in the composition for forming a resist underlayer film of the present invention, had insufficient solubility in any of the solvents examined.

[0295] The polymers (A4) and (A5) used in the composition for forming a resist underlayer film of the present invention are random polymers, and were soluble in all of a mixed solvent of PGMEA / CyHO=70 / 30, a mixed solvent of PGMEA / CyHO=50 / 50, and CyHO. This shows that the polymers used in the composition for forming a resist underlayer film of the present invention have superior solvent solubility.

[0296] In Examples 1-4 to 1-6, which used polymers (A4) and (A5), which are copolymers having two types of repeating units, and polymer (A6), which was end-capped with 2,3-naphthol, the solubility in a mixed solvent of PGMEA / CyHO=70 / 30 was improved compared to Example 1-3, which used polymer (A3).

[0297] Preparation of composition for forming resist underlayer film Each of the polymers (A1) to (A7) and the comparative polymers (R1) to (R4), and (R6) to (R10) that were evaluated to have good solubility was used to prepare a composition for forming a resist underlayer film according to the following procedure.

[0298] [Preparation of composition for forming resist underlayer film UDL-1] The polymer (A1) was dissolved in a mixed solvent of propylene glycol monomethyl ether acetate (PGMEA) and cyclohexanone (CyHO) containing 0.5 mass % of a surfactant FC-4430 (manufactured by Sumitomo 3M Limited) in the ratio shown in Table 3, and the solution was filtered through a 0.02 μm membrane filter to prepare a composition for forming a resist underlayer film (UDL-1).

[0299] [Preparation of resist underlayer film forming compositions (UDL-2 to 12) and comparative resist underlayer film forming compositions (Comparative UDL-1 to 9)] Each resist underlayer film forming composition was prepared in the same manner as for resist underlayer film forming composition UDL-1, except that the type and content of each component were as shown in Table 3. In Table 3, "-" indicates that the corresponding component was not used. A resin represented by any one of the following formulas (C1) to (C3) was used as the blend resin, a compound represented by the following formula (D1) was used as the crosslinking agent, a compound represented by the following formula (G1) was used as the acid generator (TAG), and a compound represented by the following formula (E1) was used as the flowability promoter.

[0300] [Blend resin] The blend resins (C1) to (C3) used in the resist underlayer film forming compositions UDL-8 to UDL-10 are shown below. [ka]

[0301] [Crosslinking agent] The crosslinking agent (D1) used in the resist underlayer film forming composition UDL-11 is shown below. [ka]

[0302] [Acid generator] The thermal acid generator (G1) used in the resist underlayer film forming composition UDL-11 is shown below. [ka]

[0303] [Flow enhancer] The flow promoter (E1) used in the resist underlayer film forming composition UDL-12 is shown below.

[0304] [Table 2]

[0305] [Table 3]

[0306] [Example 2 and Comparative Example 2: Evaluation of Solvent Resistance and Film Thickness Uniformity During High-Temperature Treatment in a Nitrogen Atmosphere] The above resist underlayer film forming compositions (UDL-1 to 12 and Comparative Examples UDL-1 to 9) were each applied onto a silicon substrate, baked at 350°C for 60 seconds, and then baked at 550°C for 90 seconds in a nitrogen atmosphere with an oxygen concentration controlled to 0.2% or less. The film thickness was measured from the center to the outer periphery of the substrate, and the average film thickness (a [nm]) was calculated. Next, PGMEA solvent was dispensed on it, left for 30 seconds, spin-dried, and baked at 100°C for 60 seconds to evaporate PGMEA, and the film thickness (b [nm]) was measured. The film thickness difference before and after PGMEA treatment (residual film ratio: (b / a) x 100) was calculated.

[0307] In addition, for each film obtained by firing at 550°C for 90 seconds in a nitrogen atmosphere with an oxygen concentration controlled to 0.2% or less, the film thickness was measured from the center of the substrate to the outer periphery. If the difference between the maximum and minimum film thicknesses was less than 4% of the average film thickness (a), it was rated as "very good," if it was 4-8%, it was rated as "good," and if it was 8% or more, it was rated as "poor."

[0308] The results are shown in Table 4 below.

[0309] [Table 4]

[0310] As shown in Table 4, in Examples 2-1 to 2-12, in which the resist underlayer film-forming compositions (UDL-1 to 12) of the present invention were used, 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.

[0311] 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 and minimum film thicknesses of the film baked at 550°C under a nitrogen atmosphere was less than 8% of the average film thickness (a), and it was found that the film thickness uniformity was good. In addition, Examples 2-8 to 2-11 containing the (C) blend resin and the (D) crosslinking agent were confirmed to have improved film thickness uniformity compared to Example 2-3 which did not contain them. On the other hand, Comparative Example 2-4 using a resin with a low molecular weight had a large amount of sublimate during high-temperature treatment, and the film thickness was extremely thin compared to the others, and the film thickness uniformity was also deteriorated. In Comparative Example 2-5, it is presumed that the heat resistance was deteriorated, possibly due to the use of a polymer (R6) containing a repeating unit having a hydroxyl group, and the film thickness uniformity was deteriorated due to intense thermal decomposition.

[0312] [Example 3 and Comparative Example 3: Filling characteristics and flatness evaluation] Embeddability evaluation: The above resist underlayer film forming compositions (UDL-1 to 11 and Comparative Examples UDL-1 to 9) were each applied onto a SiO2 wafer substrate having a dense line & space pattern (line width 60 nm, line depth 100 nm, distance between the centers of two adjacent lines (120 nm)), baked at 350°C for 60 seconds using a hot plate, and then baked at 550°C for 90 seconds in a nitrogen atmosphere with an oxygen concentration controlled to 0.2% or less to form a resist underlayer film with a thickness of 100 nm. The substrate used was a base substrate 9 (SiO2 wafer substrate) having a dense line & space pattern as shown in Figure 2(Q) (overhead view) and (R) (cross-sectional view).

[0313] The cross-sectional shape of each of the obtained wafer substrates was observed using an electron microscope (S-4700) manufactured by Hitachi, Ltd., to confirm whether or not there were voids (air gaps) inside the resist underlayer film that filled the gaps between the lines. The results are shown in Table 5. When a composition for forming a resist underlayer film with poor filling properties was used, voids were generated inside the resist underlayer film that filled the gaps between the lines in this evaluation. When a composition for forming a resist underlayer film with good filling properties was used, a resist underlayer film 10 without voids was filled inside the resist underlayer film that filled the gaps between the lines of a base substrate 9 having a dense line and space pattern, as shown in FIG. 2(S).

[0314] Flatness evaluation: For the base substrate 11 (SiO2 wafer substrate) having a dense line and space pattern as shown in Figure 3 (T), the cross-sectional shape of each wafer substrate obtained in the above-mentioned filling characteristic evaluation as shown in Figure 3 (U) was observed using a scanning electron microscope (SEM), and the step Delta 12 of the filling film 12 between the dense line pattern part and the non-line pattern forming part was observed using an electron microscope (S-4700) manufactured by Hitachi, Ltd. In this evaluation, it can be said that the smaller the step, the better the flattening characteristic. The results are shown in Table 5.

[0315] [Table 5]

[0316] As shown in Table 5, it was confirmed that Examples 3-1 to 3-12, which used the resist underlayer film forming composition (UDL-1 to 12) of the present invention, were capable of filling dense line and space patterns without generating voids, and had good filling properties.

[0317] In addition, when Example 3-1 and Example 3-12 are compared, Example 3-12 has a better flatness. This is believed to be due to the improvement of thermal fluidity by adding the flow promoter (E1).

[0318] On the other hand, voids were generated in Comparative Example 3-4, which used a low molecular weight COPNA resin, and Comparative Example 3-5, which used a polymer (R6) containing a repeating unit having a hydroxyl group. It is presumed that the voids were generated due to decomposition products because the heat resistance of both of these resins was significantly insufficient.

[0319] [Example 4 and Comparative Example 4: Etching Resistance Evaluation] The above resist underlayer film forming compositions (UDL-1 to 12 and Comparative Examples UDL-1 to 9) were each applied onto a silicon substrate, and the coating film was heated at 350°C for 60 seconds using a hot plate to form a resist underlayer film (350°C baked film), and the film thickness a was measured. Next, etching was performed using CF4 gas under the following conditions using a Tokyo Electron etching device Telius, and the film thickness b was measured. The film thickness etched per minute using each gas was calculated as the etching rate A (nm / min) from the film thickness (film thickness a-film thickness b) etched during a specified time.

[0320] In addition, separately from the above, the above resist underlayer film forming compositions (UDL-1 to 12 and Comparative Examples UDL-1 to 9) were applied onto silicon substrates, and the coating film was heated at 350°C for 60 seconds using a hot plate to prepare a substrate, which was then baked at 450°C or 550°C for 90 seconds in a nitrogen atmosphere with an oxygen concentration controlled to 0.2% or less to form a resist underlayer film (high-temperature baked film), and the film thickness c was measured. Next, etching was performed using CF4 gas under the following conditions using a Tokyo Electron etching device Telius, and the film thickness d was measured. The film thickness etched per minute was calculated as the etching rate B (nm / min) from the film thickness (film thickness c-film thickness d) etched during a specified time using each gas. The results are shown in Table 6 below.

[0321] The etching resistance of the film sintered at high temperatures of 450°C or 550°C was compared with that of the film sintered at 350°C, and the improvement in etching resistance due to high temperature sintering at 450°C or 550°C (etching rate B (nm / min) - etching rate A (nm / min)) was calculated. The results are shown in Table 6 below.

[0322] The etching conditions are as follows.

[0323] Dry etching conditions with CF4 gas Chamber pressure: 50mT RF power (top): 500W RF power (bottom): 300W CF4 gas flow rate: 150sccm CHF3 gas flow rate: 50sccm Time: 30sec

[0324] [Table 6]

[0325] 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 using CF4 gas was 70 nm / min or less in the film baked at 350 ° C., and it was found that the etching resistance was excellent. In addition, the etching resistance of the film baked at 450 ° C. or 550 ° C. in a nitrogen atmosphere controlled to an oxygen concentration of 0.2% or less was further improved, and an improvement of 10 nm / min or more in the etching rate was observed compared to the film baked at 350 ° C. This is presumably because the resist underlayer film forming composition of the present invention is a high-carbon material in which thermal decomposition of the cured film actively occurs by high-temperature baking, and therefore when baked at 450 ° C. or 550 ° C., decomposition and recombination of carbon bonds occur, and the cured film becomes densified. In addition, in Examples 4-2 to 4-5, Examples 4-7, and 4-8, by increasing the temperature of high-temperature baking in a nitrogen atmosphere from 450 ° C. to 550 ° C., densification was further promoted, and high etching resistance was improved.

[0326] Furthermore, when Examples 4-1 to 4-5 are compared, it is found that the larger the condensed aromatic ring is, the higher the etching resistance of the film tends to be, among the polymers used in the composition for forming a resist underlayer film of the present invention. Among the compositions examined, the composition containing the polymer (A3) having an anthracene structure showed the highest etching resistance.

[0327] In Examples 4-6 to 4-8 using random polymers (A4) and (A5), in which improved solvent solubility was confirmed, and in Examples 4-11 to 4-14 using blend resins or crosslinking agents, in which improved film thickness uniformity was confirmed during high-temperature treatment, the etching resistance was comparable to that of Examples 4-4 and 4-5 using polymer (A3).

[0328] Compared with Example 4-10, which used polymer (A7), a resin similar to polymer (A3) in that the aromatic group represented by Ar in the above general formula (1) is anthracene, polymer (A3) showed excellent etching resistance. Polymer (A7) had a different synthesis recipe from polymer (A3) and was synthesized by Alternative Method 2. This result is presumed to be due to the fact that, as with the solubility result, molecular weight control is difficult in the synthesis by Alternative Method 2, so that the molecular weight of polymer (A7) becomes larger than that of polymer (A3), and as a result, thermal decomposition becomes difficult. Therefore, from this result, it can be seen that a composition containing a polymer synthesized by Alternative Method 1 is more preferable than a polymer synthesized by Alternative Method 2. In another aspect, it can be seen that when Ar is anthracene, the molecular weight of the polymer is preferably 800 or less.

[0329] In 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, the comparative polymer (R1) composed of a repeating unit containing a hydroxyl group was used, so the oxygen content of the resin itself was high, and the etching resistance of the film baked at 350°C was insufficient, and the etching resistance was also insufficient after baking at 550°C. In Comparative Example 4-2, which uses a comparative polymer (R2) of a novolac resin having a relatively high carbon content, the etching resistance of the film baked at 350°C was relatively good, but the improvement rate of the etching resistance at 550°C was small. This is presumably because the heat resistance of the resin was high, and it was difficult for high carbonization and densification to proceed at high temperatures.

[0330] In Comparative Example 4-3, which used a high-carbon, rigid Comparative Polymer (R3), the repeating unit of Comparative Polymer (R3) did not have an oxygen atom, so the etching resistance of the film baked at 350°C was comparable to that of the resin used in the Examples of the present invention, and was a good result. However, since the repeating unit of Comparative Polymer (R3) did not have a group that promotes thermal decomposition, such as a methylene group, the improvement rate of the etching resistance of this resin at high temperature baking was small.

[0331] In Comparative Example 4-4, which used a comparative polymer (R4) having the same structure as the resin of the present invention but a smaller molecular weight, the improvement rate of etching resistance after high-temperature baking was comparable to that of the product of the present invention. However, the film thickness uniformity and embedding / flatness after high-temperature baking were insufficient, possibly due to a significant lack of heat resistance, making it difficult to apply the film as a resist underlayer film.

[0332] In Comparative Example 4-5, which used a comparative polymer (R6) having a substituted aromatic group together with a COPNA resin component, the thermal decomposition was large, but the degree of improvement in etching resistance was smaller than that of the resin of the present invention. This is presumably because the ratio of the COPNA resin component, which is likely to form an amorphous carbon-like film by thermal decomposition, was small.

[0333] In Comparative Examples 4-6 to 9, which used Comparative Polymers (R7) to (R10) having structures relatively similar to those of the resins used in the Examples of the present invention, the etching resistance of the film baked at 350° C. was relatively good, but the improvement rate of the etching resistance when baked at 550° C. was small. This is probably because, as in the case of R2 above, the heat resistance was increased by including a repeating unit having a hydroxyl group, and high carbonization and densification were difficult to proceed with high-temperature baking.

[0334] In order to form a resist underlayer film having excellent etching resistance, a composition containing a polymer having a structure represented by any one of the general formulas (1) to (3) is preferable.

[0335] [Example 5 and Comparative Example 5: Pattern Forming Method] The above resist underlayer film forming compositions (UDL-1 to 12 and Comparative Examples UDL-1 to 9) were applied onto a silicon wafer substrate on which a SiO2 film having a trench pattern (trench width 10 μm, trench depth 0.10 μm) was formed, and the coating film was baked in air at 350 ° C for 60 seconds. Thereafter, the coating film was heated at 550 ° C for 90 seconds in a nitrogen atmosphere in which the oxygen concentration was controlled to 0.2% or less, to form a resist underlayer film with a thickness of 100 nm. Next, a silicon atom-containing resist intermediate layer material (SOG-1) was applied onto the resist underlayer film, and the coating film was baked at 220 ° C for 60 seconds to form a resist intermediate layer film with a thickness of 20 nm. Next, an ArF single layer resist of the resist upper layer film material was applied onto the resist intermediate layer film, and the coating film was baked at 105 ° C for 60 seconds to form a photoresist film with a thickness of 100 nm. Furthermore, a liquid immersion protective film material (TC-1) was applied onto the photoresist film, and the coating film was baked at 90° C. for 60 seconds to form a protective film with a thickness of 50 nm.

[0336] The silicon-containing resist intermediate layer material (SOG-1) was prepared as follows. The polymer represented by ArF silicon-containing intermediate film polymer (SiP1) and the crosslinking catalyst (CAT1) were dissolved in an organic solvent containing 0.1 mass % of FC-4430 (manufactured by Sumitomo 3M Limited) in the ratio shown in Table 7. The resulting mixture was filtered through a fluorine resin filter with a pore size of 0.10 μm to prepare the silicon-containing resist intermediate layer material (SOG-1).

[0337] [Table 7]

[0338] The structural formulae of the ArF silicon-containing intermediate film polymer (SiP1) and crosslinking catalyst (CAT1) used are shown below.

[0339] [ka]

[0340] The resist top layer film material (ArF single layer resist) was prepared by the following procedure. First, the polymer (RP1), acid generator (PAG1), and basic compound (Amine1) were dissolved in a solvent containing 0.1 mass% of surfactant FC-4430 (Sumitomo 3M Limited) in the ratios shown in Table 8. The resulting mixture was filtered through a 0.10 μm fluorine resin filter to obtain a resist top layer film material.

[0341] [Table 8]

[0342] The polymer (RP1), acid generator (PAG1), and basic compound (Amine1) used in the resist top layer material (ArF single layer resist) are shown below.

[0343] [ka]

[0344] The immersion protective film material (TC-1) was prepared by the following procedure. First, the protective film polymer (PP1) was dissolved in an organic solvent in the ratio shown in Table 9. The resulting mixture was filtered through a 0.10 μm fluororesin filter to obtain an immersion protective film material.

[0345] [Table 9]

[0346] The polymer (PP1) used in the immersion protective film material (TC-1) is shown below.

[0347] [ka]

[0348] Next, the resist was exposed using an ArF immersion exposure tool (Nikon Corporation; NSR-S610C, NA 1.30, σ 0.98 / 0.65, 35 degree dipole s-polarized illumination, 6% halftone phase shift mask), baked at 100°C for 60 seconds (PEB), and developed in a 2.38 mass% tetramethylammonium hydroxide (TMAH) aqueous solution for 30 seconds to obtain a 55 nm 1:1 positive line and space pattern (resist pattern).

[0349] Next, the silicon-containing resist intermediate layer material (SOG-1) was etched by dry etching using the resist pattern as a mask using a Tokyo Electron etching device Telius to form a hard mask pattern (SOG-1 pattern). The resist underlayer film was etched using the obtained SOG-1 pattern as a mask to form a resist underlayer film pattern. Then, the SiO2 film was etched using the obtained resist underlayer film pattern as a mask. The etching conditions are as shown below.

[0350] Transfer conditions of resist pattern to silicon-containing resist intermediate layer material (SOG-1). Chamber pressure: 50mT RF power (top): 500W RF power (bottom): 300W CF4 gas flow rate: 150sccm CHF3 gas flow rate: 50sccm Time: 15sec

[0351] Conditions for transferring the silicon atom-containing resist intermediate layer material (SOG-1) pattern to the resist underlayer film. Chamber pressure: 10mT RF power (top): 1,000W RF power (bottom): 300W CO2 gas flow rate: 320sccm N2 gas flow rate: 80sccm Time: 30sec

[0352] Transfer conditions of resist underlayer film pattern onto SiO2 film. Chamber pressure: 10mT RF Power (Top): 100W RF power (bottom): 800W CF4 gas flow rate: 25sccm CHF3 gas flow rate: 15sccm O2 gas flow rate: 5sccm Time: 100sec

[0353] The cross section of the pattern formed on the SiO2 film was observed with an electron microscope (S-4700) manufactured by Hitachi, Ltd. The results are shown in Table 10. "-" means that the film was not formed properly and was not evaluated.

[0354] [Table 10]

[0355] As shown in Table 10, in Examples 5-1 to 5-12 in which the resist underlayer film forming composition (UDL-1 to 12) of the present invention was used, the resist upper layer film pattern was finally transferred well to the SiO2 film on the substrate in all cases, and it was confirmed that the resist underlayer film forming composition of the present invention is suitable for fine processing by the multilayer resist method. On the other hand, in Comparative Examples 5-1 to 5-3 and Comparative Examples 5-6 to 5-9 in which Comparative Examples UDL-1 to 3 and Comparative Examples UDL-6 to 9 were used, in which the etching resistance was confirmed to be insufficient for the resist underlayer film forming composition of the present invention in the above etching resistance evaluation, the pattern shape after substrate transfer etching was vertical, but deterioration of LWR was observed after substrate processing. In Comparative Examples 5-4 and 5-5 in which voids were generated in the embedding evaluation, pattern collapse occurred.

[0356] From the above, it has become clear that the composition for forming a resist underlayer film of the present invention has both extremely good dry etching resistance and high filling and / or planarization properties, and is therefore extremely useful as a resist underlayer film material for use in a multilayer resist method, and that the pattern formation method of the present invention using this composition makes it possible to form a fine pattern with high precision even if the workpiece is a substrate having steps.

[0357] The present specification includes the following aspects. [1] A composition for forming a resist underlayer film, A polymer (A) having a repeating unit represented by the following general formula (1): (B) Organic solvent Contains A composition for forming a resist underlayer film, wherein the molecular weight of the polymer (A) is 300 to 3,000, and the polymer (A) does not contain any repeating unit having a hydroxyl group as a substituent, nor any repeating unit having a heteroaromatic ring. [ka] (In the above formula (1), Ar is an unsubstituted divalent aromatic group having 6 to 30 carbon atoms.) [2] The composition for forming a resist underlayer film according to [1], wherein the aromatic group Ar is any one of the following structures (1-a): [ka] (In the above formula (1-a), * indicates the bonding position with the methylene group in the general formula (1).) [3] The composition for forming a resist underlayer film according to [1] or [2], wherein the aromatic group Ar is any one of naphthalene, anthracene, phenanthrene, and pyrene. [4] The resist underlayer film forming composition according to any one of [1] to [3], wherein the polymer (A) is a copolymer having two types of repeating units represented by the following general formula (2): [ka] (In the above formula (2), Ar1 is any one of naphthalene, anthracene, phenanthrene, and pyrene, and Ar2 has a structure different from Ar1 and is any one selected from the following formula (1-a). a+b is 100, 30≦a≦99, and 1≦b≦70.) [ka] [5] The resist underlayer film forming composition according to [4], wherein the polymer (A), which is a copolymer having two types of repeating units represented by the above 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): [ka] (In the above formula, Ar1 is any one of naphthalene, anthracene, phenanthrene, and pyrene, Ar2 has a structure different from Ar1 and is any one selected from the above formula (1-a), and X is a hydroxy group, an alkoxy group having 1 to 4 carbon atoms, or a halogen group.) [6] The resist underlayer film forming composition according to [5], wherein Ar1 in the formula (2) is anthracene. [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. [8] The composition for forming a resist underlayer film according to any one of [1] to [7], wherein the polymer (A) has a terminal capping group represented by the following general formula (3): [ka] (In the above formula (3), * is a bond to the methylene group in the above formula (1), d is an integer of 1 to 9, and e is an integer of 0 to 2.) [9] The composition for forming a resist underlayer film according to any one of [1] to [8], further comprising a (C) blend resin which is a phenol resin or a resin containing a phenolic hydroxy group.

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

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

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

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

[11] , wherein the blend resin (C) is a resin represented by any one of the following general formulas (C-1), (C-2) and (C-3): [ka] (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.) [ka] (In the above formula (C-2), q is an integer of 0 or 1, and r is an integer of 1 to 6.) [ka] (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 composition for forming a resist underlayer film according to any one of [1] to

[12] , further comprising (D) a crosslinking agent having a structure represented by the following general formula (4): [ka] 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). [ka] (In the above formula (5), * indicates a bond position.)

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

[13] , further comprising (E) a flowability promoter having a weight loss rate of less than 30% at temperatures from 30°C to 190°C and a weight loss rate of 98% or more at temperatures from 30°C to 350°C.

[15] The composition for forming a resist underlayer film according to

[14] , wherein the (E) flowability promoter contains one or more compounds selected from the group consisting of compounds represented by the following general formulas (i) to (iii): [ka] (In the above formula (i), R1's are each 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 a 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.) [ka] (In the above formula (i-1), * indicates a bond position, and 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. 10 and W 11 are each independently a single bond or a carbonyl group. i and j are integers of 0 to 10, and i+j≧1. [ka] (In the above formula (i-2), * indicates a bond position.) [ka] (In the above formula (ii), R2 is each 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 a 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.) [ka] (In the above formula (ii-1), * indicates a bond position, and R 20 , R 21 , R 22 and R 23 are each 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. [ka] (In the above formula (ii-2), * indicates a bond position.) [ka] (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 either an aromatic ring or a divalent group represented by the following general formula (iii-1). W6 and W7 are each a single bond or a 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).) [ka] (In the above formula (iii-1), * indicates a bond position, and W 30 is an organic group having 1 to 4 carbon atoms. [ka] (In the above formula (iii-2), * indicates a bond position.)

[16] The composition for forming a resist underlayer film further comprises: (F) a surfactant, (G) an acid generator, and (H) Plasticizer The composition for forming a resist underlayer film according to any one of [1] to

[15] , which contains one or more of the following:

[17] A method for forming a pattern on a workpiece substrate, comprising: (I-1) a step of applying a composition for forming a resist underlayer film according to any one of [1] to

[16] onto a substrate to be processed to obtain a coating film, and then heat-treating the coating film to form a resist underlayer film; (I-2) forming a resist upper layer film on the resist underlayer film using a photoresist material; (I-3) a step of forming a pattern on the resist upper layer film by pattern-exposing the resist upper layer film and then developing the resist upper layer film with a developer; (I-4) a step of transferring the pattern to the resist underlayer film by dry etching using the resist upper layer film on which the pattern is formed as a mask; and (I-5) A step of processing the substrate to be processed using the resist underlayer film on which the pattern has been formed as a mask to form a pattern on the substrate to be processed. A pattern forming method comprising the steps of:

[18] A method for forming a pattern on a workpiece substrate, comprising: (II-1) A step of applying a composition for forming a resist underlayer film according to any one of [1] to

[16] onto a substrate to be processed to obtain a coating film, and then heat-treating the coating film 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) a step of forming a pattern on the resist upper layer film by pattern-exposing the resist upper layer film and then developing the resist upper layer film with a developer; (II-5) a step of transferring the pattern to the resist intermediate film by dry etching using the resist upper layer film on which the pattern has been formed as a mask; (II-6) a step of transferring a pattern to the resist underlayer film by dry etching using the resist intermediate film to which the pattern has been transferred as a mask; and (II-7) A step of processing the substrate to be processed using the resist underlayer film on which the pattern has been formed as a mask to form a pattern on the substrate to be processed. A pattern forming method comprising the steps of:

[19] A method for forming a pattern on a workpiece substrate, comprising the steps of: (III-1) A step of applying a composition for forming a resist underlayer film according to any one of [1] to

[16] onto a substrate to be processed to obtain a coating film, and then heat-treating the coating film 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 oxynitride 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 top layer film on the organic thin film using a photoresist material; (III-5) a step of forming a pattern on the resist upper layer film by pattern-exposing the resist upper layer film and then developing the resist upper layer film with a developer; (III-6) a step of transferring a pattern to the organic thin film and the inorganic hard mask intermediate film by dry etching using the resist upper layer film on which the pattern has been formed as a mask; (III-7) a step of transferring a pattern to the resist underlayer film by dry etching using the inorganic hard mask intermediate film to which the pattern has been transferred as a mask; and (III-8) A step of processing the substrate to be processed using the resist underlayer film on which the pattern has been formed as a mask to form a pattern on the substrate to be processed. A pattern forming method comprising the steps of:

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

[17] to

[19] , wherein the substrate to be processed has a structure or step having a height of 30 nm or more.

[21] A method for forming a resist underlayer film that functions as an organic flat film used in a manufacturing process of a semiconductor device, comprising spin-coating a composition for forming a resist underlayer film according to any one of [1] to

[16] on a substrate to be processed to obtain a coating film, and curing the coating film by heat-treating it at a temperature of 450°C or higher and 800°C or lower for 10 to 600 seconds to form a resist underlayer film.

[22] A method for forming a resist underlayer film that functions as an organic flat film used in a manufacturing process of a semiconductor device, comprising spin-coating a composition for forming a resist underlayer film according to any one of [1] to

[16] on a substrate to be processed to obtain a coating film, and curing the coating film by heat-treating it in an atmosphere with an oxygen concentration of 1% or more and 21% or less to form a resist underlayer film.

[23] A method for forming a resist underlayer film that functions as an organic flat film used in a manufacturing process of a semiconductor device, comprising spin-coating a composition for forming a resist underlayer film according to any one of [1] to

[16] on a substrate to be processed to obtain a coating film, and curing the coating film by heat-treating it in an atmosphere with an oxygen concentration of less than 1%, thereby forming a resist underlayer film.

[24] The method for forming a resist underlayer film according to any one of

[21] to

[23] , wherein the substrate to be processed has a structure or step having a height of 30 nm or more.

[0358] The present invention is not limited to the above-described embodiment. The above-described embodiment is merely an example, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits similar effects is included in the technical scope of the present invention. [Explanation of symbols]

[0359] 1...supporting substrate, 1a...substrate to be processed, 2...layer to be processed, 2a...pattern (pattern formed in layer to be processed), 2b...reverse pattern (reverse pattern formed in layer to be processed), 3...resist underlayer film, 3a...resist underlayer film pattern, 4...resist intermediate film, 4a...resist intermediate film pattern, 5...resist top layer film, 5a...resist top layer film pattern, 6...exposed portion, 9...underlying substrate having dense line and space pattern, 10...resist underlayer film, 11...underlying substrate having dense line and space pattern, 12...filling film, Delta 12...step between the filling film and the line pattern dense portion and the non-line pattern forming portion.

Claims

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

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

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

4. 2. The resist underlayer film forming composition according to claim 1, wherein the polymer (A) is a copolymer having two kinds of repeating units represented by the following general formula (2): 【Chemistry 3】 (In the above formula (2), Ar １ is any one of naphthalene, anthracene, phenanthrene, and pyrene, and Ar ２ is Ar １ and is any one selected from the following formula (1-a), where a+b is 100, 30≦a≦99, and 1≦b≦70. 【Chemistry 4】

5. The resist underlayer film forming composition according to claim 4, wherein the polymer (A), which is a copolymer having two kinds of repeating units represented by the above 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): 【Chemistry 5】 (In the above formula, Ar １ is any one of naphthalene, anthracene, phenanthrene, and pyrene, and Ar ２ is Ar １ and is any one selected from the above formula (1-a), and X is a hydroxy group, an alkoxy group having 1 to 4 carbon atoms, or a halogen group.

6. Ar in the formula (2) １ The resist underlayer film forming composition according to claim 5 , wherein is anthracene.

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

8. 2. The composition for forming a resist underlayer film according to claim 1, wherein the polymer (A) has an end-capping group represented by the following general formula (3): 【Chemistry 6】 (In the above formula (3), * is a bond to the methylene group in the above formula (1), d is an integer of 1 to 9, and e is an integer of 0 to 2.)

9. 2. The composition for forming a resist underlayer film according to claim 1, further comprising a blend resin (C) which is a phenol resin or a resin containing a phenolic hydroxy group.

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

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

12. The resist underlayer film forming composition according to claim 9, wherein the blend resin (C) is a resin represented by any one of the following general formulas (C-1), (C-2) and (C-3): 【Chemistry 7】 (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.) 【Chemistry 8】 (In the above formula (C-2), q is an integer of 0 or 1, and r is an integer of 1 to 6.) 【Chemistry 9】 (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 composition for forming a resist underlayer film according to claim 1 , further comprising (D) a crosslinking agent having a structure represented by the following general formula (4): 【Chemistry 10】 (In the above formula (4), Ar ３ and Ar ４ each represents a benzene ring or a naphthalene ring which may have a substituent, 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): 【Chemistry 11】 (In the above formula (5), * indicates a bond position.)

14. The composition for forming a resist underlayer film according to claim 1, further comprising (E) a flowability promoter having a weight loss rate of less than 30% from 30° C. to 190° C. and a weight loss rate of 98% or more from 30° C. to 350° C.

15. The composition for forming a resist underlayer film according to claim 14, wherein the flowability promoter (E) contains one or more compounds selected from the group consisting of compounds represented by the following general formulas (i) to (iii): 【Chemistry 12】 (In the above formula (i), R １ are each independently a hydrogen atom, a hydroxyl group, or an optionally substituted organic group having 1 to 10 carbon atoms. １ W is a phenylene group or a divalent group represented by the following general formula (i-1): ２ and W ３ are each a single bond or a 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. 【Chemistry 13】 (In the above formula (i-1), * indicates a bond position, and 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. １０ and W １１ are each independently a single bond or a carbonyl group. i and j are integers from 0 to 10, and i+j≧1. 【Chemistry 14】 (In the above formula (i-2), * indicates a bond position.) 【Chemistry 15】 (In the above formula (ii), R ２ are each independently a hydrogen atom or an optionally substituted organic group having 1 to 10 carbon atoms. ４ is a divalent group represented by the following general formula (ii-1): ５ is a single bond or a divalent group represented by the following general formula (ii-2), where k is an integer of 0 to 5, and l is an integer of 2 to 10. 【Chemistry 16】 (In the above formula (ii-1), * indicates a bond position, and R ２０ , R ２１ , R ２２ and R ２３ are each a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms; m and n are integers from 0 to 10, and m+n≧1. 【Chemistry 17】 (In the above formula (ii-2), * indicates a bond position.) 【Chemistry 18】 (In the above formula (iii), R ３ and R ４ 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. ５ and R ６ are each an organic group having 1 to 10 carbon atoms, R ５ is a group containing either an aromatic ring or a divalent group represented by the following general formula (iii-1): ６ and W ７ are each a single bond or a 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). 【Chemistry 19】 (In the above formula (iii-1), * indicates a bond position, and W ３０ is an organic group having 1 to 4 carbon atoms. 【Chemistry 20】 (In the above formula (iii-2), * indicates a bond position.)

16. The composition for forming a resist underlayer film further comprises (F) a surfactant, (G) an acid generator, and (H) Plasticizer 2. The composition for forming a resist underlayer film according to claim 1, which comprises one or more of the following:

17. A method for forming a pattern on a workpiece substrate, comprising the steps of: (I-1) A step of applying the composition for forming a resist underlayer film according to any one of claims 1 to 16 onto a substrate to be processed to obtain a coating film, and then heat-treating the coating film to form a resist underlayer film; (I-2) forming a resist upper layer film on the resist underlayer film using a photoresist material; (I-3) a step of pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern on the resist upper layer film; (I-4) a step of transferring the pattern to the resist underlayer film by dry etching using the resist upper layer film on which the pattern is formed as a mask; and (I-5) A step of processing the substrate to be processed using the resist underlayer film on which the pattern has been formed as a mask to form a pattern on the substrate to be processed. A pattern forming method comprising the steps of:

18. A method for forming a pattern on a workpiece substrate, comprising the steps of: (II-1) A step of applying the composition for forming a resist underlayer film according to any one of claims 1 to 16 onto a substrate to be processed to obtain a coating film, and then heat-treating the coating film 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) a step of forming a pattern on the resist upper layer film by pattern-exposing the resist upper layer film and then developing the resist upper layer film with a developer; (II-5) a step of transferring a pattern to the resist intermediate film by dry etching using the resist upper layer film on which the pattern has been formed as a mask; (II-6) a step of transferring a pattern to the resist underlayer film by dry etching using the resist intermediate film to which the pattern has been transferred as a mask; and (II-7) A step of processing the substrate to be processed using the resist underlayer film on which the pattern has been formed as a mask to form a pattern on the substrate to be processed. A pattern forming method comprising the steps of:

19. A method for forming a pattern on a workpiece substrate, comprising the steps of: (III-1) A step of applying the composition for forming a resist underlayer film according to any one of claims 1 to 16 onto a substrate to be processed to obtain a coating film, and then heat-treating the coating film 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 oxynitride 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 top layer film on the organic thin film using a photoresist material; (III-5) a step of pattern-exposing the resist upper layer film and then developing the same with a developer to form a pattern on the resist upper layer film; (III-6) a step of transferring a pattern to the organic thin film and the inorganic hard mask intermediate film by dry etching using the resist upper layer film on which the pattern has been formed as a mask; (III-7) A step of transferring a pattern to the resist underlayer film by dry etching using the inorganic hard mask intermediate film to which the pattern has been transferred as a mask; and (III-8) A step of processing the substrate to be processed using the resist underlayer film on which the pattern is formed as a mask to form a pattern on the substrate to be processed. A pattern forming method comprising the steps of:

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

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

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

23. A method for forming a resist underlayer film that functions as an organic flat film used in a manufacturing process of a semiconductor device, comprising spin-coating a composition for forming a resist underlayer film according to any one of claims 1 to 16 on a substrate to be processed to obtain a coating film, and curing the coating film by heat-treating it at a temperature of 450°C or higher and 800°C or lower for 10 to 600 seconds to form a resist underlayer film.

24. 17. A method for forming a resist underlayer film that functions as an organic flat film used in a manufacturing process of a semiconductor device, comprising spin-coating a composition for forming a resist underlayer film according to any one of claims 1 to 16 onto a substrate to be processed to obtain a coating film, and curing the coating film by heat-treating it in an atmosphere with an oxygen concentration of 1% or more and 21% or less to form a resist underlayer film.

25. 17. A method for forming a resist underlayer film that functions as an organic flat film used in a manufacturing process of a semiconductor device, comprising spin-coating a composition for forming a resist underlayer film according to any one of claims 1 to 16 onto a substrate to be processed to obtain a coating film, and curing the coating film by heat-treating it in an atmosphere with an oxygen concentration of less than 1%, thereby forming a resist underlayer film.

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

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

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

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