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

Abstract

To provide a resist underlayer film forming composition or the like which exhibits extremely superior dry etching resistance compared to conventional resist underlayer film materials.SOLUTION: The resist underlayer film forming composition contains (A) a polymer having a structure represented by the following general formula (1A), (B) a crosslinking agent of a structure represented by the following general formula (B-1), and (C) an organic solvent. The polymer (A) does not contain a hydroxyl group. The content of the crosslinking agent (B) is 5-50 pts.mass based on 100 pts.mass of the polymer (A).SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] As LSIs become more highly integrated and faster, pattern dimensions are becoming increasingly fine. Lithography technology has achieved this by shortening the wavelength of light sources and selecting appropriate resist compositions to match. Single-layer positive photoresist compositions have become the key to this. These single-layer positive photoresist compositions incorporate a backbone that provides etching resistance to dry etching with chlorine- or fluorine-based gas plasma, and a switching mechanism that dissolves exposed areas. This allows the exposed areas to be dissolved to form a pattern, and the remaining resist pattern is then used as an etching mask to dry etch the substrate.

[0003] However, if the thickness of the photoresist film used is made finer, i.e., the pattern width is made smaller, the resolution of the photoresist film decreases, and when an attempt is made to develop the photoresist film into a pattern using a developer, the aspect ratio becomes too large, resulting in pattern collapse. For this reason, photoresist films have been made thinner as patterns become finer.

[0004] On the other hand, substrate processing typically involves dry etching using a patterned photoresist film as an etching mask. However, in reality, no dry etching method can achieve perfect etching selectivity between the photoresist film and the substrate. As a result, the photoresist film can be damaged and disintegrated during substrate processing, preventing accurate transfer of the resist pattern to the substrate. Therefore, as patterns become finer, resist compositions are required to have higher dry etching resistance. However, to improve resolution, resins used in photoresist compositions must have low light absorption at the exposure wavelength. As a result, as exposure light wavelengths have become shorter (i-line, KrF, and ArF), resins have evolved, such as novolac resins, polyhydroxystyrenes, and resins with aliphatic polycyclic skeletons. However, in reality, the etching rates under dry etching conditions during substrate processing have become faster, and recent photoresist compositions with high resolution tend to have weaker etching resistance.

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

[0006] One method for solving these problems is the multilayer resist method, in which a resist underlayer film having etching selectivity different from that of 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 formed on the resist upper layer film, and then the pattern is transferred to the resist underlayer film by dry etching using the resist upper layer film pattern as a dry etching mask, and the pattern is further transferred to the substrate to be processed by dry etching using the resist underlayer film as a dry etching mask.

[0007] One type of multilayer resist method is the three-layer resist method, which can be performed using a typical resist composition used in single-layer resist methods. In this three-layer resist method, for example, an organic film made of a novolac resin or the like is deposited on a substrate to be processed as a resist underlayer, a silicon-containing resist intermediate film is deposited on top of that as a resist intermediate film, and a conventional organic photoresist film is deposited on top of that as a resist upper layer. When dry etching is performed using a fluorine-based gas plasma, the organic resist upper layer exhibits a favorable etching selectivity relative to the silicon-containing resist intermediate film, allowing the resist upper layer pattern to be transferred to the silicon-containing resist intermediate film by dry etching with a fluorine-based gas plasma. This method allows for pattern transfer to the silicon-containing resist intermediate film (resist intermediate film) even when using a resist composition that is difficult to directly form a pattern with a sufficient thickness for processing the substrate or that does not have sufficient dry etching resistance for substrate processing. Subsequent pattern transfer by dry etching with an oxygen- or hydrogen-based gas plasma allows for the formation of a pattern in an organic film (resist underlayer) made of a novolac resin or the like that has sufficient dry etching resistance for substrate processing. Many resist underlayer films such as those described above are already known, for example, those described in Patent Document 1.

[0008] On the other hand, in recent years, the miniaturization of DRAM memories has accelerated, and there is an increasing need for resist underlayer films that have further improved dry etching resistance and excellent filling and planarization properties. As a coat-type resist underlayer film material that has 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 coat-type resist underlayer film materials is approaching.

[0009] To address the above-mentioned problem, Patent Document 3 reports that etching resistance during substrate processing can be improved by heating a resist underlayer film in an atmosphere with an oxygen concentration of less than 1% by volume at a temperature higher than 450°C and equal to or lower than 800°C. However, the resist underlayer films used in the above examples often contain resins or compounds containing hydroxyl groups or propargyl groups, which leaves oxygen atoms in the film and are therefore considered undesirable from the perspective of etching resistance. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-205685 [Patent Document 2] Patent No. 6714493 [Patent Document 3] Patent No. 6711104 Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a composition for forming a resist underlayer film that exhibits extremely superior dry etching resistance compared to conventional resist 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. [Means for solving the problem]

[0012] In order to solve the above-mentioned problems, the present invention provides a composition for forming a resist underlayer film, comprising: (A) a polymer having a structure represented by the following general formula (1A); (B) a crosslinking agent having a structure represented by the following general formula (B-1); and (C) an organic solvent, wherein the (A) polymer does not contain a hydroxyl group; and the content of the (B) crosslinking agent is 5 to 50 parts by mass relative to 100 parts by mass of the (A) polymer. [ka] (In general formula (1A), R1 is any one of a hydrogen atom, a halogen atom, and a linear, branched, or cyclic hydrocarbon group having 1 to 20 carbon atoms.) [ka] (In general formula (B-1), W1 and W2 each independently represent a benzene ring or a naphthalene ring which may have a substituent, R2 each independently represent a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, and X is a group represented by the following formula (2).) [ka] (In formula (2), * indicates the bond position.)

[0013] Such a composition for forming a resist underlayer film is a combination of a polymer having a structure represented by the above general formula (1A) and a crosslinking agent having a structure represented by the above general formula (B-1), and the composition does not contain a polymer containing a hydroxyl group, so that it is possible to form a high-carbon film that has excellent etching resistance during substrate processing by thermal curing.

[0014] It is preferable that the composition further contains a polymer having a partial structure represented by the following general formula (1B). [ka] (In general formula (1B), R'2, R3, and R4 each independently represent a hydrogen atom, a halogen atom, or a linear, branched, or cyclic hydrocarbon group having 1 to 20 carbon atoms.)

[0015] When the composition further contains a polymer having a partial structure represented by the general formula (1B), the thermal fluidity is improved, and it is possible to provide a composition for forming a resist underlayer film that is excellent in embedding ability and flatness for uneven substrates.

[0016] The polymer (A) preferably has a structure represented by the following general formula (1C). [ka] (In the general formula (1C), a, b, and c are in the ranges of a+b+c=1, 0.5≦a≦0.9, and 0.1≦b+c≦0.5, respectively.)

[0017] When the polymer (A) is a composition for forming a resist underlayer film having a structure represented by the general formula (1C), it becomes possible to achieve a high level of both etching resistance during substrate processing and embedding ability / flatness for uneven substrates.

[0018] The weight average molecular weight Mw of the polymer (A) as measured by gel permeation chromatography in terms of polystyrene is preferably 500 to 5,000.

[0019] When the weight-average molecular weight Mw of the polymer (A) is within the above range, the composition for forming a resist underlayer film has good thermal fluidity, and therefore when blended into a resist underlayer film material, it is possible to form a resist underlayer film that not only satisfactorily fills the microstructure formed on the substrate but also flattens the entire substrate.Furthermore, it is possible to provide a resist underlayer film that produces a small amount of sublimation product during baking.

[0020] The ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn of the (B) crosslinking agent, as determined by gel permeation chromatography in terms of polystyrene, is preferably 1.00≦Mw / Mn≦1.25.

[0021] If the molecular weight dispersity of the (B) crosslinking agent is as described above, the thermal fluidity of the composition for forming a resist underlayer film will be good, and therefore when the crosslinking agent is blended into a resist underlayer film material, not only will it be possible to satisfactorily embed the fine structures formed on the substrate, but it will also be possible to form a resist underlayer film that flattens the entire substrate.

[0022] It is preferable that the composition contains (D) a flow promoter that has 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.

[0023] The flow promoter (D) contributes to improving the flowability of the composition during application and is removed from the film after baking at 350° C., thereby improving filling / planarization properties without deteriorating dry etching resistance. In addition, it can suppress the occurrence of defects caused by drying, contributing to improving yields in semiconductor manufacturing.

[0024] In this case, it is preferable that the (D) flowability promoter contains one or more compounds selected from the following general formulas (i) to (iii). [ka] (In general 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, and W 1 is a phenylene group or a divalent group represented by the following general formula (i-1), and W 2 and W 3 are each independently a single bond or a divalent group represented by the following formula (i-2), and m 1 is an integer between 1 and 10, and n 1 is an integer between 0 and 5.) [ka] (In general formula (i-1), * indicates a bonding position, and R 10 , R 11 , R 12 , and R 13 are each independently a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms; W 10 and W 11 are each independently a single bond or a carbonyl group, and m 10 , m 11 is an integer between 0 and 10, and m 10 +m 11≧1.) [ka] (In formula (i-2), * indicates a bonding position.) [ka] (In general formula (ii), R 2 are each independently a hydrogen atom or an optionally substituted organic group having 1 to 10 carbon atoms, W 4 is a divalent group represented by the following general formula (ii-1), and W 5 is a single bond or a divalent group represented by the following formula (ii-2), and m 2 is an integer between 2 and 10, and n 3 is an integer between 0 and 5.) [ka] (In general formula (ii-1), * indicates a bonding position, and R 20 , R 21 , R 22 , and R 23 are each independently a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms, and m 20 , m 21 is an integer between 0 and 10, and m 20 +m 21 ≧1.) [ka] (In formula (ii-2), * indicates the bonding position.) [ka] (In general formula (iii), R 3 and R 4 are each independently 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; R 5 and R 6 are each independently an organic group having 1 to 10 carbon atoms, and R 5is a group containing either an aromatic ring or a divalent group represented by the following general formula (iii-1), and W 6 and W 7 is a single bond or a divalent group represented by the following formula (iii-2), and at least one of them is a divalent group represented by the following formula (iii-2). [ka] (In general formula (iii-1), * indicates a bonding position, and W 30 is an organic group having 1 to 4 carbon atoms. [ka] (In formula (iii-2), * indicates a bonding position.)

[0025] The polymer (A) is imparted with thermal fluidity by the addition of the fluidity promoter (D) containing one or more compounds selected from the general formulae (i) to (iii) above, and the composition for forming a resist underlayer film thus has both high filling and planarization properties.

[0026] The composition preferably further contains one or more of (E) a surfactant, (F) an acid generator, and (G) a plasticizer.

[0027] A composition for forming a resist underlayer film containing the above additives will have better coatability, dry etching resistance, and filling / planarization properties.

[0028] The present invention also provides a method for forming a pattern on a substrate to be processed, 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, followed by heat treatment 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 has been 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:

[0029] By using the pattern forming method using the two-layer resist process, a fine pattern can be formed on a workpiece (substrate).

[0030] The present invention also provides a method for forming a pattern on a substrate to be processed, 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, followed by heat treatment 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 pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern on the resist upper layer film; (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:

[0031] The pattern formation method using the three-layer resist process described above makes it possible to form a fine pattern on a workpiece with high precision.

[0032] The present invention also provides 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 described above onto a substrate to be processed, followed by heat treatment 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 it with a developer to form a pattern on the resist upper layer film; (III-6) a step of transferring the 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) 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:

[0033] The pattern formation method using the four-layer resist process described above makes it possible to form a fine pattern on a workpiece with high precision.

[0034] In the pattern formation method of the present invention, the substrate to be processed may be a substrate having a structure or step having a height of 30 nm or more.

[0035] The pattern formation method of the present invention uses the composition for forming a resist underlayer film of the present invention, which can form a resist underlayer film having high-level filling / planarization properties, and is therefore particularly useful for microfabrication of substrates having such structures or steps.

[0036] 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, the method comprising spin-coating the composition for forming a resist underlayer film described above onto a substrate to be processed, and heat-treating the substrate coated with the composition for forming a resist underlayer film at a temperature of 100°C or higher and 800°C or lower for 10 to 600 seconds to form a cured film.

[0037] 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, the method comprising spin-coating the composition for forming a resist underlayer film described above onto a substrate to be processed, and heat-treating the substrate coated with the composition for forming a resist underlayer film in an atmosphere having an oxygen concentration of 1% or more and 21% or less, thereby forming a cured film.

[0038] By using such a method, the crosslinking reaction during the formation of the resist underlayer film can be promoted, and mixing with the resist toplayer film can be more effectively suppressed. In addition, by appropriately adjusting the heat treatment temperature, time, and oxygen concentration within the above ranges, the resist underlayer film can have filling / planarization properties and curing properties suitable for the application.

[0039] 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, the method comprising spin-coating the composition for forming a resist underlayer film described above onto a substrate to be processed, and heat-treating the substrate coated with the composition for forming a resist underlayer film in an atmosphere with an oxygen concentration of less than 1%, thereby forming a cured film.

[0040] This method is useful because it promotes the crosslinking reaction during the formation of the resist underlayer film and more effectively suppresses mixing with the resist toplayer film without causing deterioration of the substrate to be processed, even when the substrate contains a material that is unstable when heated in an oxygen atmosphere.

[0041] 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.

[0042] The method for forming a resist underlayer film of the present invention uses the composition for forming a resist underlayer film of the present invention, which can form a resist underlayer film having high-level filling / planarizing properties, and is therefore particularly suitable for forming a resist underlayer film on a substrate having such structures or steps. [Effects of the Invention]

[0043] As described above, the resist underlayer film-forming composition, pattern formation method, and resist underlayer film-forming method of the present invention are particularly suitable for use in multilayer resist processes, including filling / planarizing uneven or uneven substrates, and are extremely useful in fine patterning for semiconductor device manufacturing. In particular, in fine patterning processes using multilayer resist methods in semiconductor device manufacturing processes, even on substrates with difficult-to-fill / planarize areas, such as dense high-aspect-ratio fine pattern structures typified by increasingly miniaturized DRAM memory, filling is possible without causing defects such as voids or peeling, thereby forming resist underlayer films with excellent flatness. Furthermore, the resist underlayer film exhibits superior etching resistance compared to conventional resist underlayer films, and this effect can be achieved particularly by heating at temperatures above 450°C and below 800°C in an atmosphere with an oxygen concentration of less than 1% by volume. This allows for even more accurate formation of fine patterns on the substrate. [Brief explanation of the drawings]

[0044] [Figure 1] FIG. 1 is an explanatory diagram of an example of the pattern forming method of the present invention (three-layer resist process). [Figure 2] FIG. 2 is an explanatory diagram of the embedding characteristic evaluation method. [Figure 3] FIG. 3 is an explanatory diagram of the flattening characteristic evaluation method. DETAILED DESCRIPTION OF THE INVENTION

[0045] 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 to form a resist underlayer film that can transfer a resist pattern to a substrate to be processed with higher accuracy.

[0046] The present inventors focused on a method for improving the dry etching resistance of resist underlayer films during substrate processing, and embarked on the development of a composition for forming a resist underlayer film that dramatically improves dry etching resistance, and conducted extensive research. The present inventors discovered that, unlike resist underlayer film materials with excellent heat resistance, high-carbon materials that actively cause thermal decomposition of the cured film upon high-temperature baking cause decomposition and recombination of carbon bonds, resulting in densification of the cured film. The present inventors conducted further extensive research and found that a combination of a polymer having a structure represented by the above general formula (1A), which is composed almost entirely of carbon and hydrogen, and a crosslinker having the above general formula (B-1) results in a densified resist underlayer film that exhibits significantly superior dry etching resistance compared to conventional resist underlayer films, thereby completing the present invention.

[0047] That is, the present invention provides a composition for forming a resist underlayer film, comprising: (A) a polymer having a structure represented by the following general formula (1A); (B) a crosslinking agent having a structure represented by the following general formula (B-1); and (C) an organic solvent, wherein the (A) polymer does not contain a hydroxyl group; and the content of the (B) crosslinking agent is 5 to 50 parts by mass relative to 100 parts by mass of the (A) polymer: [ka] (In general formula (1A), R1 is any one of a hydrogen atom, a halogen atom, and a linear, branched, or cyclic hydrocarbon group having 1 to 20 carbon atoms.) [ka] (In general formula (B-1), W1 and W2 each independently represent a benzene ring or a naphthalene ring which may have a substituent, R2 each independently represent a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, and X is a group represented by the following formula (2).) [ka] (In formula (2), * indicates the bond position.)

[0048] The present invention will be described in detail below, but the present invention is not limited thereto.

[0049] <Composition for forming resist underlayer film> The composition for forming a resist underlayer film of the present invention comprises (A) a polymer having a structure represented by the following general formula (1A), (B) a crosslinking agent having a structure represented by the following general formula (B-1), and (C) an organic solvent, wherein the polymer (A) does not contain a hydroxyl group, and the content of the crosslinking agent (B) is 5 to 50 parts by mass relative to 100 parts by mass of the polymer (A). [ka] (In general formula (1A), R1 is any one of a hydrogen atom, a halogen atom, and a linear, branched, or cyclic hydrocarbon group having 1 to 20 carbon atoms.) [ka] (In general formula (B-1), W1 and W2 each independently represent a benzene ring or a naphthalene ring which may have a substituent, R2 each independently represent a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, and X is a group represented by the following formula (2).) [ka] (In formula (2), * indicates the bond position.)

[0050] In the above general formula (1A), R1 is any one of a hydrogen atom, a halogen atom, and a linear, branched, or cyclic hydrocarbon group having 1 to 20 carbon atoms, and is preferably a hydrogen atom from the viewpoint of etching resistance.

[0051] In the general formula (B-1) above, W1 and W2 each independently represent a benzene ring or a naphthalene ring which may have a substituent, R2 each independently represent a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, and X is a group represented by the following formula (2): From the viewpoint of raw material availability, W1 and W2 are preferably unsubstituted benzene rings, and R2 is preferably a hydrogen atom or an n-butyl group.

[0052] In the composition, the content of the (B) crosslinking agent is 5 to 50 parts by mass, preferably 10 to 40 parts by mass, and more preferably 15 to 30 parts by mass, relative to 100 parts by mass of the (A) polymer.

[0053] If the content of the (B) crosslinking agent in the composition is outside the above range, the thermosetting property of the composition for forming a resist underlayer film deteriorates, resulting in a deterioration in the thickness uniformity of the resist underlayer film and an increase in the amount of sublimation. If it is desired to improve the etching resistance of the resist underlayer film during substrate processing, it is preferable to increase the proportion of the (A) polymer, and if it is desired to improve the thickness uniformity of the resist underlayer film, it is preferable to increase the proportion of the (B) crosslinking agent. These can be adjusted according to the required performance.

[0054] The composition is preferably a composition for forming a resist underlayer film, characterized in that it further contains a polymer having a structure represented by the following general formula (1B): [ka] (In general formula (1B), R'2, R3, and R4 each independently represent a hydrogen atom, a halogen atom, or a linear, branched, or cyclic hydrocarbon group having 1 to 20 carbon atoms.)

[0055] In the above general formula (1B), it is preferable that R'2, R3, and R4 each independently represent a hydrogen atom, a halogen atom, or a linear, branched, or cyclic hydrocarbon group having 1 to 20 carbon atoms, and from the viewpoint of etching resistance, it is more preferable that R'2, R3, and R4 each represent a hydrogen atom.

[0056] The polymer having the structure represented by the general formula (1B) is not particularly limited as long as it is contained in the composition, and may be a mixed composition of a polymer having a structure represented by the general formula (1A) and a polymer having a structure represented by the general formula (1B), or may be a copolymer of the structure represented by the general formula (1A) and the structure represented by the general formula (1B).

[0057] When the composition for forming a resist underlayer film of the present invention further contains a polymer having a structure represented by the above general formula (1B), the thermal fluidity is improved, and it is possible to provide a composition for forming a resist underlayer film that is excellent in embedding ability / flatness for uneven substrates.

[0058] The composition for forming a resist underlayer film is preferably characterized in that the polymer (A) has a structure represented by the following general formula (1C). [ka] (In the general formula (1C), a, b, and c are in the ranges of a+b+c=1, 0.5≦a≦0.9, and 0.1≦b+c≦0.5, respectively.)

[0059] In the above general formula (1C), a, b, and c are preferably in the ranges of a+b+c=1, 0.5≦a≦0.9, and 0.1≦b+c≦0.5, respectively, and more preferably in the ranges of 0.7≦a≦0.9 and 0.1≦b+c≦0.3.

[0060] The weight-average molecular weight Mw of the polymer (A) as measured by gel permeation chromatography in terms of polystyrene is preferably 500 to 5,000, more preferably 1,000 to 4,500, and even more preferably 2,000 to 4,000. When the weight-average molecular weight Mw is 500 or more, the amount of sublimation is reduced, and the film thickness uniformity is not impaired. When the weight-average molecular weight Mw is 5,000 or less, the solvent solubility of the polymer is not impaired, and therefore precipitation does not occur over time, which is preferable from the viewpoint of storage stability. Furthermore, since the flowability is not impaired, the embedding ability and flatness are not impaired.

[0061] Such a weight-average molecular weight provides the resist underlayer film material with good thermal fluidity, and therefore when blended into the resist underlayer film material, it is possible to form a resist underlayer film that not only satisfactorily embeds the fine structures formed on the substrate, but also flattens the entire substrate.

[0062] The polymer (A) can be obtained by polymerizing polymerizable monomers using a known method. When obtaining a polymer, it is also possible to synthesize the polymer by polymerizing each monomer protected with a protecting group as necessary, followed by a deprotection reaction as necessary. The reaction method for obtaining the polymer is not particularly limited, and can be appropriately selected from methods such as radical polymerization and cationic polymerization, depending on the reactivity of the monomers.

[0063] Radical polymerization can be performed by mixing monomers having polymerizable unsaturated bonds, adding a radical initiator in a solvent, and then performing thermal polymerization, thereby obtaining a polymer. Polymerization conditions can be selected according to the monomers used, the target molecular weight, and other factors. Specific examples of solvents used during polymerization include toluene, benzene, tetrahydrofuran, diethyl ether, dioxane, 2-butanone, methyl isobutyl ketone, propylene glycol monomethyl ether acetate, cyclohexanone, γ-butyrolactone, ethyl acetate, and butyl acetate. Examples of polymerization initiators include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile), dimethyl 2,2-azobis(2-methylpropionate), benzoyl peroxide, and lauroyl peroxide. Thiols such as octanethiol and 2-mercaptoethanol may also be added as chain transfer agents during polymerization. The polymerization reaction can be carried out by heating preferably to 40° C. to the boiling point of the reaction solvent, and the reaction time is 0.5 to 100 hours, preferably 1 to 48 hours.

[0064] When cationic polymerization is used, a method is available in which monomers having polymerizable unsaturated bonds are mixed and a cationic polymerization initiator is added to carry out polymerization, thereby obtaining a polymer. Polymerization conditions can be selected in various ways depending on the monomers used, the target molecular weight, etc., and specific examples of solvents used during polymerization include hexane, heptane, octane, toluene, methylene chloride, 1,2-dichloroethane, ethyl ether, and butyl ether. Catalysts used as cationic polymerization initiators include acid, sulfuric acid, perchloric acid, trifluoroacetic acid, methanesulfonic acid, trichloroacetic acid, and tetrahydrofuran. RiffExamples of suitable catalysts include protonic acids such as fluoromethanesulfonic acid, chlorosulfonic acid, and fluorosulfonic acid, and Lewis acids such as boron trifluoride, aluminum chloride, titanium tetrachloride, stannic chloride, and ferric chloride. When using a Lewis acid as a catalyst, the presence of a proton source such as an acid, water, or alcohol in an amount equivalent to the moles of the catalyst may be added to improve cationic polymerization activity. The polymerization reaction is not particularly limited as long as the reaction proceeds at a temperature that is within the range of -10°C to the boiling point of the reaction solvent, but is preferably carried out by heating. The reaction time is 0.5 to 100 hours, preferably 1 to 48 hours.

[0065] The method for obtaining the polymer (A) is preferably cationic polymerization. In radical polymerization, a terminal structure containing heteroatoms other than carbon, such as oxygen and nitrogen, which deteriorate etching resistance, is introduced into the polymer due to the radical initiator, but cationic polymerization does not have this disadvantage. Therefore, cationic polymerization is preferred as a method for obtaining the polymer from the viewpoint of etching resistance.

[0066] The ratio Mw / Mn (ie, dispersity) of the weight average molecular weight Mw to the number average molecular weight Mn of the (B) crosslinking agent in terms of polystyrene as determined by gel permeation chromatography is preferably 1.00≦Mw / Mn≦1.25.

[0067] When the dispersity is within the above range, the thermal fluidity of the resist underlayer film material is not reduced, and when blended into the resist underlayer film material, it is possible to not only embed the microstructure formed on the substrate but also form a resist underlayer film that flattens the entire substrate. By definition, a monomolecular compound has an Mw / Mn of 1.00, but due to the separability of GPC, the measured value may exceed 1.00. Generally, polymers having repeating units have a very difficult Mw / Mn ratio approaching 1.00 unless a special polymerization method is used, and the Mw / Mn will be a value exceeding 1. In the present invention, in order to distinguish between monomolecular compounds and polymers, the index of monomolecularity is defined as 1.00≦Mw / Mn≦1.25.

[0068] <(C) Organic Solvent> The (C) 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, (B) crosslinking agent, and, if contained, the later-described (D) flowability promoter, (E) surfactant, (F) acid generator, (G) plasticizer, other additives, and the like.

[0069] Specifically, the organic solvents described in paragraphs

[0091] and

[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, and γ-butyrolactone, or a mixture containing one or more of these, are preferably used.

[0070] The amount of the organic solvent to be added is preferably in the range of 200 to 10,000 parts by mass, more preferably 250 to 5,000 parts by mass, per 100 parts by mass of the polymer (A).

[0071] <(D) Flow promoter> It is preferable that the composition contains (D) a flow promoter that has 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.

[0072] A flowability promoter that exhibits a weight loss rate of less than 30% between 30°C and 190°C and a weight loss rate of 98% or more between 30°C and 350°C is preferred because evaporation during heat treatment is suppressed, thereby maintaining a low viscosity, providing excellent thermal fluidity, and leaving little residual flowability 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.

[0073] The upper limit of the temperature range in which the weight loss rate of the (D) 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 fluidity promoter is less than 30% within the above temperature range, the filling / planarization properties can be further improved.

[0074] The temperature at which the weight loss rate of the (D) fluidity promoter reaches 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 reaches 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.

[0075] By incorporating the above-mentioned (D) fluidity promoter, the thermal fluidity of the composition for forming a resist underlayer film is improved from the start of heat treatment to curing by a crosslinking reaction, and therefore the composition has excellent filling / planarization properties. On the other hand, the (D) fluidity promoter is reduced by evaporation or the like during heat treatment, so that etching resistance and optical properties are not impaired.

[0076] A more preferred embodiment of the above (D) flow promoter includes one containing one or more compounds selected from the following general formulae (i) to (iii). [ka] (In general 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, and W 1 is a phenylene group or a divalent group represented by the following general formula (i-1), and W 2 and W 3 are each independently a single bond or a divalent group represented by the following formula (i-2), and m 1 is an integer between 1 and 10, and n 1 is an integer between 0 and 5.) [ka] (In general formula (i-1), * indicates a bonding position, and R 10 , R11 , R 12 , and R 13 are each independently a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms; W 10 and W 11 are each independently a single bond or a carbonyl group, and m 10 , m 11 is an integer between 0 and 10, and m 10 +m 11 ≧1.) [ka] (In formula (i-2), * indicates a bonding position.) [ka] (In general formula (ii), R 2 are each independently a hydrogen atom or an optionally substituted organic group having 1 to 10 carbon atoms, W 4 is a divalent group represented by the following general formula (ii-1), and W 5 is a single bond or a divalent group represented by the following formula (ii-2), and m 2 is an integer between 2 and 10, and n 3 is an integer between 0 and 5.) [ka] (In general formula (ii-1), * indicates a bonding position, and R 20 , R 21 , R 22 , and R 23 are each independently a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms, and m 20 , m 21 is an integer between 0 and 10, and m 20 +m 21 ≧1.) [ka] (In formula (ii-2), * indicates the bonding position.) [ka] (In general formula (iii), R 3 and R 4 are each independently 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; R 5 and R 6 are each independently an organic group having 1 to 10 carbon atoms, and R 5 is a group containing either an aromatic ring or a divalent group represented by the following general formula (iii-1), and W 6 and W 7 is a single bond or a divalent group represented by the following formula (iii-2), and at least one of them is a divalent group represented by the following formula (iii-2). [ka] (In general formula (iii-1), * indicates a bonding position, and W 30 is an organic group having 1 to 4 carbon atoms. [ka] (In formula (iii-2), * indicates a bonding position.)

[0077] In the above general 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. In the present invention, the term "organic group" means a group containing at least one carbon atom, and may further contain hydrogen, nitrogen, oxygen, sulfur, silicon, a halogen atom, or the like.

[0078] R 1 R may be a single type or a mixture of multiple types. 1 More specifically, examples of the alkyl group include 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, and a s-butoxy group. ,ofExamples include a carboxyl group, a phenyl group, 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. Of these, a hydrogen atom is more preferred.

[0079] W 1 is a phenylene group or a divalent group represented by the above general formula (i-1). 2 and W 3 are each independently a single bond or a divalent group represented by the above formula (i-2). 1 is an integer between 1 and 10, and n 1 are each independently an integer of 0 to 5.

[0080] R 10 , R 11 , R 12 , and R 13 are each independently a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms. More specifically, they are 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, or an s-butoxy group. ,of Examples include a carboxyl group, a methyl 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, a hydrogen atom and a methyl group are more preferred, and a hydrogen atom is even more preferred.

[0081] W 10 and W 11 Each m is independently a single bond or a carbonyl group. 10 , m 11 is an integer between 0 and 10, and m 10 +m 11 ≧1.

[0082] In the above general formula (ii), R 2are each independently a hydrogen atom or an optionally substituted organic group having 1 to 10 carbon atoms.

[0083] R 2 R may be a single type or a mixture of multiple types. 2 More specifically, examples of the alkyl group include a hydrogen atom, 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, and a s-butoxy group. ,of Examples include a carboxyl group, a phenyl group, 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. Of these, a hydrogen atom is more preferred.

[0084] W 4 is a divalent group represented by the above general formula (ii-1). 5 is a single bond or a divalent group represented by the above formula (ii-2). 2 is an integer between 2 and 10, and n 3 is an integer between 0 and 5.

[0085] R 20 , R 21 , R 22 , and R 23are each independently a hydrogen atom, a hydroxyl group, or an optionally substituted organic group having 1 to 10 carbon atoms. More specific examples include 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-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, a hydrogen atom and a methyl group are more preferred, and a hydrogen atom is even more preferred.

[0086] m 20 , m 21 is an integer between 0 and 10, and m 20 +m 21 ≧1.

[0087] In the above general formula (iii), R 3 and R 4 are each independently a hydrogen atom, a hydroxyl group, or an optionally substituted organic group having 1 to 10 carbon atoms. More specifically, they are hydrogen atoms, hydroxyl groups, methyl groups, ethyl groups, vinyl groups, 2,2,2-trifluoroethyl groups, propyl groups, isopropyl groups, allyl groups, butyl groups, s-butyl groups, t-butyl groups, isobutyl groups, pentyl groups, cyclopentyl groups, hexyl groups, cyclohexyl groups, cyclohexenyl groups, decyl groups, methoxy groups, ethoxy groups, propoxy groups, isopropoxy groups, butoxy groups, and s-butoxy groups. ,of Examples include a carboxyl group, a phenyl group, 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. Of these, a hydrogen atom is more preferred.

[0088] R 6 is an organic group having 1 to 10 carbon atoms. 5is an organic group having 1 to 10 carbon atoms and containing either an aromatic ring or a divalent group represented by the general formula (iii-1) above. 3 , R 4 Examples include the groups listed above.

[0089] W 6 and W 7 is a single bond or a divalent group represented by the above formula (iii-2), and at least one of them is a divalent group represented by the above formula (iii-2).

[0090] W 30 is an organic group having 1 to 4 carbon atoms. More specific examples include a methylene group, an ethylene group, a propylene group, a butylene group, a trimethylene group, and a tetramethylene group. Of these, an ethylene group is more preferred.

[0091] Specific examples of the compound represented by the above general formula (i) include, but are not limited to, the following: [ka]

[0092] Specific examples of the compound represented by the above general formula (ii) include, but are not limited to, the following: [ka]

[0093] More specific examples of the compound represented by the above general formula (iii) include, but are not limited to, the following: [ka]

[0094]

[0063] When the film-forming properties of the composition for forming a resist underlayer film, the performance of embedding / planarizing the substrate, and the like are taken into consideration comprehensively, the flowability promoter (D) 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 the following aromatic-containing compounds: (i) (Poly)ethylene glycol dibenzoate (ii) (Poly)ethylene glycol dibenzyl ether (iii) (Poly)propylene glycol dibenzyl ether (iv) (Poly)butylene glycol dibenzyl ether (v) Dibenzyl linear aliphatic dicarboxylate (vi) (Poly)ethylene glycol monobenzyl ether (vii) (Poly)phenyl ethers

[0095] [ka] In the above formula, n is an integer that results in a molecular weight of 500 or less, and is applied only within this formula.

[0096] The (D) flowability promoter used in the composition for forming a resist underlayer film of the present invention has a structure having both a hydrophobic moiety consisting of an aromatic ring and a hydrophilic moiety consisting of the (D-1) structure, and therefore has excellent compatibility with the (A) polymer, the (B) crosslinking agent, the (C) organic solvent, and other additives, and can improve the flowability of the composition without impairing the film-forming properties or storage stability. [ka] (In the formula, * indicates a bonding position, and W is an organic group having 1 to 4 carbon atoms.)

[0097] The blending amount of the (D) fluidity promoter is preferably 5 to 100 parts by mass, more preferably 10 to 50 parts by mass, per 100 parts by mass of the (A) polymer. When the blending amount of the (D) fluidity promoter is 10% by mass or more, the fluidity of the composition for forming a resist underlayer film is sufficiently improved. When the content of the (D) fluidity promoter relative to the (A) polymer is within the above range, the thermal fluidity improving effect of the resist underlayer film is sufficient, and the film-forming properties and dry etching resistance of the resulting coating film are also good.

[0098] The (D) flow promoter may be used alone or in combination of two or more.

[0099] <Other ingredients> [Crosslinking agent] In addition to the crosslinking agent (B) having the structure of general formula (B-1), a general crosslinking agent can also be added to the resist underlayer film-forming composition of the present invention. The crosslinking agent used is not particularly limited, and a wide variety of known crosslinking agents can be used. Examples include methylol or alkoxymethyl 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 added is preferably 1 to 50 parts by mass, more preferably 5 to 30 parts by mass, per 100 parts by mass of the polymer (A).

[0100] 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.

[0101] Specific examples of glycoluril crosslinking agents include tetramethoxymethylated glycoluril, tetrabutoxymethylated glycoluril, alkoxy and / or hydroxy substituted products thereof, and partial self-condensates thereof.

[0102] Specific examples of benzoguanamine-based crosslinking agents include tetramethoxymethylated benzoguanamine, tetrabutoxymethylated benzoguanamine, alkoxy- and / or hydroxy-substituted products thereof, and partial self-condensates thereof.

[0103] Specific examples of urea-based crosslinking agents include dimethoxymethylated dimethoxyethylene urea, its alkoxy and / or hydroxy substituted derivatives, and partial self-condensates thereof.

[0104] A specific example of a β-hydroxyalkylamide crosslinking agent is N,N,N',N'-tetra(2-hydroxyethyl)adipamide.Specific examples of an isocyanurate crosslinking agent are triglycidyl isocyanurate and triallyl isocyanurate.

[0105] Specific examples of the aziridine crosslinking agent include 4,4'-bis(ethyleneiminocarbonylamino)diphenylmethane and 2,2-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate].

[0106] 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.

[0107] Specific examples of epoxy-based 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.

[0108] Specific examples of polynuclear phenol-based crosslinking agents include compounds represented by the following general formula (XL-1). [ka] (In general formula (XL-1), Q is a single bond or a q-valent hydrocarbon group having 1 to 20 carbon atoms. R'3 is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. q is an integer of 1 to 5.)

[0109] Q is a single bond or a q-valent hydrocarbon group having 1 to 20 carbon atoms. q is an integer of 1 to 5, and more preferably 2 or 3. Specific examples of Q include groups obtained by removing q hydrogen atoms from methane, ethane, propane, butane, isobutane, pentane, cyclopentane, hexane, cyclohexane, methylpentane, methylcyclohexane, dimethylcyclohexane, trimethylcyclohexane, benzene, toluene, xylene, ethylbenzene, ethylisopropylbenzene, diisopropylbenzene, methylnaphthalene, ethylnaphthalene, and eicosane. R'3 is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. Specific examples of the alkyl group having 1 to 20 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a pentyl group, an isopentyl group, a hexyl group, an octyl group, an ethylhexyl group, a decyl group, and an eicosanyl group, with a hydrogen atom or a methyl group being preferred.

[0110] Specific examples of the compound represented by the general formula (XL-1) include the following compounds. Among these, hexamethoxymethylated triphenolmethane, triphenolethane, 1,1,1-tris(4-hydroxyphenyl)ethane, and tris(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene are preferred from the viewpoint of improving the curability and film thickness uniformity of the resist underlayer film. R'3 is the same as above. [ka]

[0111] [ka]

[0112] [(E) Surfactant] A surfactant (E) can be added to the resist underlayer film-forming composition of the present invention to improve the coating properties in spin coating. Examples of the surfactant (E) that can be used include those described in paragraphs

[0142] to

[0147] of JP-A No. 2009-269953. When surfactant (E) is added, the amount added is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, per 100 parts by mass of the polymer (A).

[0113] [(F) Acid generator] In the composition for forming a resist underlayer film of the present invention, an acid generator (F) can be added to further accelerate the curing reaction. The acid generator (F) can be one that generates an acid by thermal decomposition or one that generates an acid by light irradiation, and either can be added. Specifically, the materials described in paragraphs

[0061] to

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

[0114] The acid generator (F) may be used alone or in combination of two or more. When the acid generator (F) is added, the amount added is preferably 0.05 to 50 parts by mass, more preferably 0.1 to 10 parts by mass, per 100 parts by mass of the polymer (A).

[0115] [(G) Plasticizer] In addition, a (G) plasticizer can be added to the resist underlayer film-forming composition of the present invention to further improve planarization / filling properties. The (G) plasticizer is not particularly limited, and a wide variety of known plasticizers can be used. Examples include low-molecular-weight compounds such as phthalates, adipates, phosphates, trimellitates, and citrates, as well as polymers such as polyethers, polyesters, and polyacetal polymers described in JP 2013-253227 A. When a (G) plasticizer is added, the amount added is preferably 1 to 100 parts by mass, more preferably 5 to 30 parts by mass, per 100 parts by mass of the (A) polymer.

[0116] Furthermore, in the composition for forming a resist underlayer film of the present invention, additives that impart filling / planarization properties similar to those of plasticizers are preferably used, such as liquid additives having a polyethylene glycol or polypropylene glycol structure, or thermally decomposable polymers that have 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. These thermally decomposable polymers preferably contain repeating units having an acetal structure represented by the following general formula (DP1) or (DP1a):

[0117] [ka] (In general formula (DP1), R6 is a hydrogen atom or an optionally substituted saturated or unsaturated monovalent organic group having 1 to 30 carbon atoms, and Y is a saturated or unsaturated divalent organic group having 2 to 30 carbon atoms.)

[0118] [ka] (In general formula (DP1a), R 6a is an alkyl group having 1 to 4 carbon atoms, and Y 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.

[0119] <Pattern Forming Method Using Composition for Forming Resist Underlayer Film> Further, in the present invention, there is provided a method for forming a pattern by a two-layer resist process using the composition for forming a resist underlayer film, the method 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, followed by heat treatment 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 has been 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:

[0120] The resist upper layer film in the two-layer resist process is preferably a photosensitive organometallic oxide film. Since the photosensitive organometallic oxide film exhibits etching resistance against oxygen-based gases, the dry etching of the resist lower layer film in the two-layer resist process, which is performed using the resist upper layer film as a mask, is preferably performed using an etching gas mainly containing oxygen-based gases.

[0121] Further, in the present invention, a pattern formation method by a three-layer resist process using such a composition for forming a resist underlayer film is a method for forming a pattern on a substrate to be processed, 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, followed by heat treatment 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 pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern on the resist upper layer film; (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:

[0122] A pattern formation method using a three-layer resist process will be described with reference to Figure 1. In the present invention, as a pattern formation method using such a three-layer resist process using a composition for forming a resist underlayer film, as shown in Figure 1(A), a resist underlayer film 3 is formed on a processable layer 2 on a processable substrate 1 using the composition for forming a resist underlayer film, a silicon-containing resist intermediate film 4 is formed on the resist underlayer film using a silicon-containing resist intermediate film material, and a resist upper layer film 5 is formed on the silicon-containing resist intermediate film using a photoresist material. Next, as shown in FIG. 1(B), the exposed portion 6 of the resist top layer film is pattern-exposed, and then developed with a developer as shown in FIG. 1(C) to form a resist top layer film pattern 5a on the resist top layer film; as shown in FIG. 1(D), using the patterned resist top layer film as a mask, a silicon-containing resist intermediate film pattern 4a is transferred to the silicon-containing resist intermediate film by dry etching; as shown in FIG. 1(E), using the patterned silicon-containing resist intermediate film as a mask, a resist underlayer film pattern 3a is transferred to the resist underlayer film by dry etching; and as shown in FIG. 1(F), a pattern forming method is provided in which the processable layer on the processable substrate is processed using the patterned resist underlayer film as a mask, thereby forming a pattern 2a on the processable substrate 1.

[0123] The silicon-containing resist intermediate film in the three-layer resist process exhibits resistance to etching by oxygen-based gases. Therefore, in the three-layer resist process, dry etching of the resist underlayer film using the silicon-containing resist intermediate film as a mask is preferably carried out using an etching gas mainly containing an oxygen-based gas.

[0124] Polysiloxane-based interlayers are also preferred as the silicon-containing resist interlayer in the three-layer resist process. By providing the silicon-containing resist interlayer with anti-reflection properties, reflection can be reduced. For 193 nm exposure, in particular, using an organic film containing many aromatic groups and exhibiting high etching selectivity with the substrate results in a high k value and high substrate reflection. However, by providing the silicon-containing resist interlayer with an absorption that results in an appropriate k value, reflection can be reduced, reducing substrate reflection to 0.5% or less. For silicon-containing resist interlayers with anti-reflection properties, anthracene is preferred for 248 nm and 157 nm exposure, while for 193 nm exposure, polysiloxanes with pendant light-absorbing groups containing phenyl groups or silicon-silicon bonds and crosslinked by acid or heat are preferred.

[0125] In addition, in the present invention, a pattern formation method by a four-layer resist process using such a composition for forming a resist underlayer film is provided, forming a resist underlayer film on a substrate to be processed using the composition for forming a resist underlayer film; forming a silicon-containing resist intermediate film on the resist underlayer film using a silicon-containing resist intermediate film material; forming an organic antireflective coating (BARC) or an adhesion film on the silicon-containing resist intermediate film; forming a resist top layer film on the BARC or the adhesion film using a photoresist material; the resist upper layer film is pattern-exposed and then developed with a developer to form a pattern on the resist upper layer film; Using the resist upper layer film on which the pattern has been formed as a mask, the pattern is transferred to the BARC or the adhesion film and the silicon-containing resist intermediate film by dry etching; using the silicon-containing resist intermediate film to which the pattern has been transferred as a mask, transferring the pattern to the resist underlayer film by dry etching; The present invention provides a pattern forming method, comprising the 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.

[0126] In addition, an inorganic hard mask intermediate film may be formed instead of the silicon-containing resist intermediate film. In this case, at least forming a resist underlayer film on a workpiece (substrate) using the composition for forming a resist underlayer film of the present invention; 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; forming a resist upper layer film on the inorganic hard mask intermediate film using a photoresist composition, and forming a circuit pattern on the resist upper layer film; Etching the inorganic hard mask intermediate film using the patterned resist upper layer film as a mask; Etching the resist underlayer film using the patterned inorganic hard mask intermediate film as a mask; Furthermore, by etching the workpiece using the resist underlayer film on which the pattern has been formed as a mask to form a pattern on the workpiece, a semiconductor device circuit pattern can be formed on the substrate.

[0127] As described above, when forming an inorganic hard mask intermediate film on a resist underlayer film, a silicon oxide film, a silicon nitride film, or a silicon oxynitride 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 2002-334869 A and WO 2004 / 066377 A. The thickness of the inorganic hard mask intermediate film is preferably 5 to 200 nm, more preferably 10 to 100 nm. Furthermore, a SiON film, which has a high anti-reflective coating effect, is most preferably used as the inorganic hard mask intermediate film. Since the substrate temperature during the formation of the SiON film is 300 to 500°C, the resist underlayer film must be able to withstand temperatures of 300 to 500°C. The resist underlayer film-forming composition used in the present invention has high heat resistance and can withstand high temperatures of 300 to 500°C, making it possible to combine an inorganic hard mask intermediate film formed by a CVD method or an ALD method with a resist underlayer film formed by a spin coating method.

[0128] As described above, a photoresist film can be formed as a resist top layer on the inorganic hard mask intermediate film. Alternatively, an organic antireflective coating (BARC) or adhesion film can be formed on the inorganic hard mask intermediate film by spin coating, and then a photoresist film can be formed on top of that. In particular, when a SiON film is used as the inorganic hard mask intermediate film, the two-layer antireflective coating consisting of the SiON film and the BARC can suppress reflection even in immersion lithography with a high NA exceeding 1.0. Another advantage of forming a BARC is that it reduces the footing of the photoresist pattern directly above the SiON film.

[0129] The present invention also provides 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 described above onto a substrate to be processed, followed by heat treatment 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 it with a developer to form a pattern on the resist upper layer film; (III-6) a step of transferring the 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) 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:

[0130] In the pattern formation method, the resist top layer film may be either positive or negative, and the same photoresist composition as commonly used may be used. The photoresist composition may also contain metal atoms such as Sn, In, Ga, Ge, Al, Ce, La, Cs, Zr, Hf, Ti, Bi, Sb, and Zn. When forming the resist top layer film using the photoresist composition, it may be formed by spin coating or by vapor deposition using a CVD or ALD method.

[0131] When forming a photoresist composition by spin coating, the photoresist composition is prebaked after application, preferably at 60 to 180°C for 10 to 300 seconds. Then, 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 film is not particularly limited, but is preferably 10 to 500 nm, and more preferably 20 to 400 nm.

[0132] When a photoresist composition is formed by deposition using a CVD or ALD method, the photoresist composition is an EUV-sensitive metal oxide-containing film, and the metal is selected from Sn, Zr, Hf, Ti, Bi, Sb, etc., with Sn being preferred due to its excellent EUV sensitivity. The metal oxide-containing film may be a photosensitive organometallic oxide-containing film such as an organotin oxide (e.g., haloalkyltin, alkoxyalkyltin, or amidoalkyltin). Specific examples of suitable precursors include trimethyltin chloride, dimethyltin dichloride, methyltin trichloride, tris(dimethylamino)methyltin(IV), and (dimethylamino)trimethyltin(IV).

[0133] Metal oxide-containing films may be deposited by PECVD or PEALD, for example, using a Lam Vector® tool. In the ALD example, the Sn oxide precursor is separated from the O precursor / plasma. The deposition temperature is preferably in the range of 50°C to 600°C. The deposition pressure is preferably between 100 and 6,000 mTorr. The metal oxide-containing film precursor liquid flow rate (e.g., organotin oxide precursor) may be 0.01 to 10 cm / s, and the gas flow rate (CO2, CO, Ar, N2) may be 100 to 10,000 sccm. The plasma power may be 200 to 1,000 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 2,000 Å.

[0134] Examples of 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.

[0135] The method for forming a pattern on the resist upper layer film is preferably photolithography with a wavelength of 5 nm or more and 300 nm or less, direct writing with an electron beam, nanoimprinting, or a combination thereof.

[0136] In the pattern forming method, the development method is preferably alkaline development or development using an organic solvent.

[0137] Next, etching is performed using the obtained resist upper layer film pattern as a mask. In the three-layer resist process, etching of the silicon-containing resist intermediate film or inorganic hard mask intermediate film is performed using a fluorocarbon-based gas, using the resist upper layer film pattern as a mask. This forms a silicon-containing resist intermediate film pattern or inorganic hard mask intermediate film pattern.

[0138] Next, the resist underlayer film is etched using the silicon-containing resist intermediate film pattern or inorganic hard mask intermediate film pattern as a mask, preferably using an etching gas mainly containing an oxygen-based gas.

[0139] The next etching of the workpiece can also be carried out using standard methods. For example, if the workpiece is made of SiO2, SiN, or a silica-based low-k insulating film, etching is carried out using mainly fluorocarbon gases. When etching the substrate with fluorocarbon gases, the silicon-containing resist intermediate film pattern in the three-layer resist process is removed at the same time as the substrate is processed.

[0140] 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.

[0141] 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 with a workpiece layer formed thereon. The workpiece layer may be a low-k film or a stopper film thereof, such as Si, SiO2, SiON, SiN, p-Si, α-Si, W, W-Si, Al, Cu, or Al-Si, and may be formed to a thickness of typically 50 to 10,000 nm, particularly 100 to 5,000 nm. When forming a workpiece layer, the substrate and workpiece layer are made of different materials.

[0142] In the pattern formation method of the present invention, the substrate to be processed may be a substrate having a structure or step having a height of 30 nm or more.

[0143] <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, which comprises spin-coating the composition for forming a resist underlayer film described above onto a substrate to be processed, and heat-treating the substrate coated with the composition for forming a resist underlayer film at a temperature of 100°C or higher and 800°C or lower for 10 to 600 seconds to form a cured film.

[0144] 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, which comprises spin-coating the composition for forming a resist underlayer film described above onto a substrate to be processed, and heat-treating the substrate coated with the composition for forming a resist underlayer film in an atmosphere with an oxygen concentration of 1% or more and 21% or less, thereby forming a cured film.

[0145] 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 comprising spin-coating the composition for forming a resist underlayer film described above onto a substrate to be processed, and heat-treating the substrate coated with the composition for forming a resist underlayer film in an atmosphere with an oxygen concentration of less than 1%, thereby forming a cured film.

[0146] In the resist underlayer film formation method of the present invention, the resist underlayer film formation composition is coated onto a substrate to be processed using a spin coating method or the like. Using a spin coating method or the like can achieve excellent filling properties. After spin coating, the organic solvent is evaporated, and baking is performed to promote the crosslinking reaction and prevent mixing with the resist top layer film or resist intermediate film. Baking is performed at a temperature range of 100°C to 800°C, preferably 300°C to 800°C, and more preferably 450°C to 800°C, for 10 to 600 seconds, preferably 10 to 300 seconds. By appropriately adjusting the baking temperature and time within the above ranges, planarization and filling properties suitable for the application, as well as curing properties such as dry etching resistance and heat resistance, can be obtained. Baking at a temperature range of 450°C to 800°C can achieve particularly excellent dry etching resistance. At a baking temperature of 100°C or higher, curing proceeds sufficiently, preventing mixing with the resist top layer film or resist intermediate film. If the baking temperature is set to 800° C. or less, thermal decomposition of the base resin can be suppressed, the film thickness does not decrease, and the film surface becomes uniform.

[0147] The atmosphere during baking can be selected as needed 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 heat treating in an atmosphere with an oxygen concentration of less than 1%.

[0148] In the method for forming a resist underlayer film using the composition for forming a resist underlayer film of the present invention, it is preferable to use a substrate to be processed having structures or steps having a height of 30 nm or more. As described above, the composition for forming a resist underlayer film of the present invention has excellent filling / planarizing properties, so that a flat cured film can be formed even if the substrate to be processed has structures or steps (irregularities) having a height of 30 nm or more. The height of the structures or steps of the substrate to be processed is preferably 30 nm or more, more preferably 50 nm or more, and even more preferably 100 nm or more. In the method for processing a stepped substrate having a pattern with the above height, forming a film using the composition for forming a resist underlayer film of the present invention and performing filling / planarization makes it possible to uniformize the film thickness of the subsequently formed resist intermediate film and resist top layer film, which is highly preferable, as it makes it easier to ensure a depth of exposure margin (DOF) during photolithography. [Example]

[0149] The present invention will be described in more detail below with reference to Synthesis Examples, Comparative Synthesis Examples, Examples, and Comparative Examples, but is not limited thereto. Regarding 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 calculated.

[0150] Synthesis example (A) Polymer synthesis

[0151] [Synthesis Example 1] Synthesis of polymer (A1) Under a nitrogen atmosphere, 3.8 g of methanesulfonic acid and 30 g of methylene chloride were mixed and homogenized at an internal temperature of 30°C. A mixture of 30.0 g of acenaphthylene and 60.0 g of methylene chloride was then added dropwise over 1 hour, and the mixture was heated and stirred at an internal temperature of 35°C for 24 hours. After cooling to room temperature, 300 g of toluene was added, and the mixture was washed six times with 100 g of pure water. The organic layer was evaporated to dryness under reduced pressure. 90 g of THF was added to the residue to form a homogeneous solution, which was then crystallized in 600 g of methanol. The precipitated crystals were separated by filtration, washed twice with 300 g of methanol, and then recovered. The recovered crystals were dried in vacuo at 70°C to obtain 28.7 g of polymer (A1). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (A1): Mw = 2,400, Mw / Mn = 1.93 [ka]

[0152] [Synthesis Example 2] Synthesis of polymer (A2) 37.5 g of propylene glycol monomethyl ether acetate (PGMEA) was heated and stirred at 80°C under a nitrogen atmosphere. To this was added a mixture of 50.0 g of acenaphthylene and 82.5 g of PGMEA, and a mixture of 3.8 g of dimethyl 2,2-azobis(2-methylpropionate) and 30.0 g of PGMEA, simultaneously and separately, over 2 hours. After heating and stirring for an additional 24 hours, the mixture was cooled to room temperature. The reaction solution was added dropwise to 750 g of methanol to crystallize the polymer. The precipitated crystals were separated by filtration, washed twice with 300 g of methanol, and then recovered. The recovered crystals were dried in vacuo at 70°C to obtain 48.3 g of polymer (A2). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (A2): Mw = 4,100, Mw / Mn = 1.73 [ka]

[0153] [Synthesis Example 3] Synthesis of polymer (A3) Under a nitrogen atmosphere, 3.8 g of methanesulfonic acid and 30 g of methylene chloride were mixed and homogenized at an internal temperature of 30°C. A mixture of 15.0 g of acenaphthylene, 11.5 g of indene, and 60.0 g of methylene chloride was then added dropwise over 1 hour, and the mixture was heated and stirred at an internal temperature of 35°C for 24 hours. After cooling to room temperature, 300 g of toluene was added, and the mixture was washed six times with 100 g of pure water. The organic layer was evaporated to dryness under reduced pressure. 90 g of THF was added to the residue to form a homogeneous solution, which was then crystallized in 600 g of methanol. The precipitated crystals were separated by filtration, washed twice with 300 g of methanol, and then recovered. The recovered crystals were dried in vacuo at 70°C to obtain 25.3 g of polymer (A3). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (A3): Mw = 2,100, Mw / Mn = 1.85 [ka]

[0154] [Synthesis Example 4] Synthesis of polymer (A4) Under a nitrogen atmosphere, 3.8 g of methanesulfonic acid and 31.6 g of methylene chloride were mixed and homogenized at an internal temperature of 30°C. A mixture of 24.0 g of acenaphthylene, 7.6 g of 9-vinylcarbazole, and 63.2 g of methylene chloride was then added dropwise over 1 hour, followed by heating and stirring at an internal temperature of 35°C for 24 hours. After cooling to room temperature, 300 g of toluene was added, and the mixture was washed six times with 100 g of purified water. The organic layer was evaporated to dryness under reduced pressure. 95 g of THF was added to the residue to form a homogeneous solution, which was then crystallized in 630 g of methanol. The precipitated crystals were separated by filtration, washed twice with 300 g of methanol, and then recovered. The recovered crystals were dried in vacuo at 70°C to obtain 30.1 g of polymer (A4). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (A4): Mw = 3,500, Mw / Mn = 2.05 [ka]

[0155] [Synthesis Example 5] Synthesis of polymer (A5) 37.5 g of propylene glycol monomethyl ether acetate (PGMEA) was heated and stirred at 80°C under a nitrogen atmosphere. To this mixture, a mixture of 38.0 g of acenaphthylene, 12.0 g of 9-vinylcarbazole, and 82.5 g of PGMEA, and a mixture of 3.6 g of dimethyl 2,2-azobis(2-methylpropionate) and 30.0 g of PGMEA were added simultaneously and separately over 2 hours. After heating and stirring for an additional 24 hours, the mixture was cooled to room temperature. The reaction solution was added dropwise to 750 g of methanol to crystallize the polymer. The precipitated crystals were separated by filtration, washed twice with 300 g of methanol, and then recovered. The recovered crystals were dried in vacuo at 70°C to obtain 46.8 g of polymer (A5). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (A5): Mw = 4,800, Mw / Mn = 2.23 [ka]

[0156] [Synthesis Example 6] Synthesis of polymer (A6) Under a nitrogen atmosphere, 5.7 g of methanesulfonic acid and 29.5 g of methylene chloride were mixed and homogenized at an internal temperature of 30°C. A mixture of 15.0 g of acenaphthylene, 6.9 g of indene, 7.6 g of 9-vinylcarbazole, and 59.0 g of methylene chloride was added dropwise over 1 hour, and the mixture was heated and stirred at an internal temperature of 35°C for 24 hours. After cooling to room temperature, 300 g of toluene was added, and the mixture was washed six times with 100 g of purified water. The organic layer was evaporated to dryness under reduced pressure. 90 g of THF was added to the residue to form a homogeneous solution, which was then crystallized in 600 g of methanol. The precipitated crystals were separated by filtration, washed twice with 300 g of methanol, and then recovered. The recovered crystals were dried in vacuo at 70°C to obtain 27.9 g of polymer (A6). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (A6): Mw = 4,000, Mw / Mn = 2.15 [ka]

[0157] Synthesis Example (B) Synthesis of crosslinker

[0158] [Synthesis Example 7] Synthesis of crosslinking agent (B1) A mixture of 219 g of bis(4-bromophenyl) ether and 1,000 mL of t-butyl methyl ether was cooled to -20°C under a N2 atmosphere, and 500 mL of a 2.67 M hexane solution of n-butyllithium was added. The mixture was stirred at -20°C for 20 minutes. 229 g of 9-fluorenone was added, and the mixture was gradually warmed to room temperature and stirred at room temperature for 4 hours. Water was added to quench the reaction. After washing with water and concentrating under reduced pressure, hexane was added, and the resulting solid was collected by filtration, washed with hexane, and dried under reduced pressure to obtain 293 g of crosslinker (B1). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (B1): Mw = 540, Mw / Mn = 1.02 [ka]

[0159] [Synthesis Example 8] Synthesis of crosslinker (B2) Under a nitrogen atmosphere, 26.4 g (1.09 mol) of magnesium was weighed into a 5 L four-neck flask. 168 g (0.54 mol) of 4,4'-dibromobiphenyl, pre-dissolved in 1,000 mL of anhydrous tetrahydrofuran (THF), and 23.0 g (0.54 mol) of lithium chloride were added to the flask, just enough to cover the magnesium. A small amount of dibromoethane was added to initiate the reaction, and the remaining THF solution was added dropwise over 3 hours while maintaining the exothermic reaction. After the addition was complete, 500 mL of THF was added, and the mixture was refluxed for 8 hours to prepare the Grignard reagent. After cooling to an internal temperature of 55°C, 150 g (0.83 mol) of 9-fluorenone, pre-dissolved in 400 mL of anhydrous THF, was added dropwise over 2 hours. After the addition was complete, the mixture was refluxed for 5.5 hours. The flask was then cooled in an ice bath, and the reaction was quenched with 1,000 mL of saturated aqueous ammonium chloride and 1,000 mL of pure water. At this time, a white precipitate formed in the solution, turning it into a suspension. 150 ml of MIBK (methyl isobutyl ketone) was added to the reaction solution, and the suspension was transferred to a separatory funnel. The aqueous layer was extracted and washed with 500 ml of pure water. The organic layer was then concentrated under reduced pressure. Recrystallization was carried out with diisopropyl ether, and the resulting white crystals were filtered and dried to obtain 109 g of crosslinker (B2). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (B2): Mw = 530, Mw / Mn = 1.02 [ka]

[0160] [Synthesis Example 9] Synthesis of crosslinker (B3) 30.0 g of crosslinker (B1) and 172.8 g of 1-butanol were suspended at an internal temperature of 80°C under a nitrogen atmosphere. 16.8 g of methanesulfonic acid was slowly added, and the reaction was carried out at an internal temperature of 100°C for 6 hours. After cooling in an ice bath to precipitate crystals, the precipitated crystals were separated by filtration, washed twice with 200 g of butanol, and three times with 200 g of diisopropyl ether, and then recovered. The recovered crystals were dried in a vacuum at 60°C to obtain 34.2 g of crosslinker (B3). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (B3): Mw = 640, Mw / Mn = 1.01 [ka]

[0161] Comparative Synthesis Example Synthesis of Comparative Polymer The comparative polymers (R1) and (R2) were synthesized using the following compounds of group G: (G1) to (G3). [ka]

[0162] [Comparative Synthesis Example 1] Synthesis of Comparative Polymer (R1) The polymer reported in [Synthesis Example 1] of JP 2021-084974 A was synthesized. 50.0 g of compound (G1), 31.6 g of compound (G2), and 300 g of 1,2-dichloroethane were suspended under a nitrogen atmosphere at an internal temperature of 60°C. 8 ml of methanesulfonic acid was slowly added, and after confirming that the heat generation had subsided, the reaction was carried out at an internal temperature of 60°C for 6 hours. After cooling to room temperature, 500 ml of methyl isobutyl ketone was added, and the organic layer was washed six times with 100 g of pure water and then evaporated to dryness under reduced pressure. 150 g of tetrahydrofuran (THF) was added to the residue to form a homogeneous solution, and the polymer was reprecipitated with 1,000 g of hexane. The precipitated polymer was separated by filtration, washed twice with 300 g of hexane, and then recovered. The recovered polymer was vacuum dried at 50°C to obtain comparative polymer (R1). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (R1): Mw = 2,120, Mw / Mn = 1.83 [ka]

[0163] [Comparative Synthesis Example 2] Synthesis of Comparative Polymer (R2) The polymer reported in [Synthesis Example 1] of JP 2021-138851 A was synthesized. 54.5 g of fluorenol (G3) and 200 g of 1,2-dichloroethane were mixed and heated to 50°C. 20.3 g of methanesulfonic acid was slowly added dropwise, and the mixture was heated and stirred at 70°C for 6 hours. After cooling to room temperature, 650 g of toluene was added, and the mixture was washed six times with 100 g of pure water. The organic layer was evaporated to dryness under reduced pressure. 200 g of THF was added to the residue to form a homogeneous solution, which was then crystallized in 600 g of methanol. The precipitated crystals were separated by filtration, washed twice with 200 g of methanol, and then recovered. The recovered crystals were dried under vacuum at 70°C to obtain 60.7 g of comparative polymer (R2). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (R2): Mw = 2,700, Mw / Mn = 1.39 [ka]

[0164] [Comparative Synthesis Example 3] Synthesis of Comparative Polymer (R3) A 200 mL flask was charged with 15.2 g of acenaphthylene, 3.3 g of 4-hydroxystyrene, and 60 g of 1,2-dichloroethane as a solvent. 1 g of trifluoroboron was added as a polymerization initiator, and the mixture was heated to 60°C and reacted for 25 hours. 1 L of methanol and 500 g of water were added to the reaction solution to precipitate the polymer. The resulting white solid was filtered and dried, yielding 12 g of Comparative Polymer (R3). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (R3): Mw = 8,800, Mw / Mn = 1.82 [ka]

[0165] [Comparative Synthesis Example 4] Synthesis of Comparative Polymer (R4) Under a nitrogen atmosphere, 5.0 g of methanesulfonic acid and 30.0 g of methylene chloride were mixed and homogenized at an internal temperature of 30°C. A mixture of 30.0 g of indene and 60.0 g of methylene chloride was then added dropwise over 1 hour, and the mixture was heated and stirred at an internal temperature of 35°C for 24 hours. After cooling to room temperature, 300 g of toluene was added, and the mixture was washed six times with 100 g of pure water. The organic layer was evaporated to dryness under reduced pressure. 90 g of THF was added to the residue to form a homogeneous solution, which was then crystallized in 600 g of methanol. The precipitated crystals were separated by filtration, washed twice with 300 g of methanol, and then recovered. The recovered crystals were dried in vacuo at 70°C to obtain 26.9 g of Comparative Polymer (R4). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (R4): Mw = 2,500, Mw / Mn = 1.83 [ka]

[0166] [Comparative Synthesis Example 5] Synthesis of Comparative Polymer (R5) Under a nitrogen atmosphere, 1.9 g of methanesulfonic acid and 30.0 g of methylene chloride were mixed and homogenized at an internal temperature of 30°C. A mixture of 30.0 g of 9-vinylcarbazole and 60.0 g of methylene chloride was then added dropwise over 1 hour, followed by heating and stirring at an internal temperature of 35°C for 24 hours. After cooling to room temperature, 300 g of toluene was added, and the mixture was washed six times with 100 g of pure water. The organic layer was evaporated to dryness under reduced pressure. 90 g of THF was added to the residue to form a homogeneous solution, which was then crystallized in 600 g of methanol. The precipitated crystals were separated by filtration, washed twice with 300 g of methanol, and then recovered. The recovered crystals were dried under vacuum at 70°C to obtain 29.3 g of Comparative Polymer (R5). The weight average molecular weight (Mw) and dispersity (Mw / Mn) were determined by GPC, and the following results were obtained. (R5): Mw = 3,800, Mw / Mn = 2.18 [ka]

[0167] [Composition for forming resist underlayer film UDL-1] Polymer (A1), crosslinking agent (B1), and a flowability promoter (D-1) described below as an additive were dissolved in a mixed solvent of propylene glycol monomethyl ether acetate (PGMEA) and cyclohexanone (CyHO) containing 0.5 mass % of surfactant FC-4430 (manufactured by Sumitomo 3M Limited) in the proportions shown in Table 2, and the resulting solution was filtered through a 0.02 μm membrane filter to prepare a composition for forming a resist underlayer film (UDL-1).

[0168] [Preparation of Resist Underlayer Film-Forming Compositions (UDL-2 to 10) and Comparative Resist Underlayer Film-Forming Compositions (Comparative UDL-1 to 7)] Each composition was prepared in the same manner as UDL-1, except that the type and content of each component were as shown in Table 2. In Table 2, "-" indicates that the corresponding component was not used. The acid generator (TAG) used was the one represented by formula (F-1) below, the flow promoter used was the one represented by formula (D-1) below, and the comparative crosslinker used was the one represented by formula (XL-1) below.

[0169] [Acid generator] The acid generator (F-1) used in the composition for forming a resist underlayer film is shown below. [ka]

[0170] [Flow promoter] Table 1 shows the flowability promoter (D-1) used in the composition for forming a resist underlayer film. [Table 1]

[0171] [Comparative crosslinker] The comparative crosslinking agent (XL-1) used in Comparative Example UDL-5 is shown below. [ka]

[0172] [Table 2]

[0173] [Solvent Resistance Evaluation and Film Thickness Uniformity Evaluation (Examples 1-1 to 1-10, Comparative Examples 1-1 to 1-7)] The resist underlayer film-forming compositions (UDL-1 to 10, Comparative Examples UDL-1 to 7) prepared above were applied to silicon substrates and baked at 350°C for 60 seconds. The film thickness was measured from the center to the periphery of the substrate, and the average film thickness (a [nm]) was calculated. Subsequently, PGMEA solvent was dispensed onto the substrate, left for 30 seconds, spin-dried, and baked at 100°C for 60 seconds to evaporate the PGMEA, and the film thickness (b [nm]) was measured. The difference in film thickness before and after PGMEA treatment (residual film ratio: (b / a) × 100) was calculated. In addition, for films baked at 350°C for 60 seconds, the film thickness was measured from the center of the substrate to the outer periphery, and if the difference between the maximum and minimum film thicknesses was less than 5% of the average film thickness (a), it was rated as "good," and if it was 5% or more, it was rated as "poor." The results are shown in Table 3 below.

[0174] [Table 3]

[0175] As shown in Table 3, Examples 1-1 to 1-10, which used the resist underlayer film-forming compositions (UDL-1 to 10) of the present invention, had a film remaining rate ((b / a) × 100) of 99% or more after PGMEA rinsing, indicating that a crosslinking reaction occurred and sufficient solvent resistance was achieved. On the other hand, Comparative Example 1-4, which used Comparative Example UDL-4, which did not contain a crosslinking agent, had solvent resistance of less than 99%, possibly due to insufficient thermosetting properties. Furthermore, in Examples 1-1 to 1-10, which used the resist underlayer film-forming compositions (UDL-1 to 10) of the present invention, the difference between the maximum and minimum film thicknesses of the films baked at 350°C was less than 5% of the average film thickness (a), demonstrating good film thickness uniformity. On the other hand, in Comparative Example UDL-4, which did not contain a crosslinker, and Comparative Examples 1-4, 1-6, and 1-7, which used polymers different from those of the present invention, the difference between the maximum and minimum film thicknesses of the films baked at 350°C was 5% or more of the average film thickness (a), demonstrating insufficient film thickness uniformity. It is presumed that the absence of a crosslinker in Comparative Example UDL-4 resulted in insufficient thermosetting of the polymer, leading to the sublimation of a large amount of uncured components of the polymer upon baking at 350°C. It is presumed that Comparative Examples UDL-6 and 7 exhibited significantly lower heat resistance of the polymer, resulting in severe thermal decomposition upon baking at 350°C.

[0176] [Evaluation of Filling Characteristics and Flatness (Examples 2-1 to 2-10, Comparative Examples 2-1 to 2-6)] Embeddability evaluation: Each of the resist underlayer film-forming compositions (UDL-1 to 10 and comparative examples UDL-1 to 3, 5 to 7) that had a favorable solvent resistance rating was applied to a SiO2 wafer substrate with a dense line and space pattern (line width 60 nm, line depth 100 nm, center-to-center distance of adjacent two lines 120 nm) and heated at 350°C for 60 seconds using a hot plate to form a 100 nm thick resist underlayer film. The substrate used was base substrate 7 (SiO2 wafer substrate) with a dense line and space pattern as shown in Figure 2(G) (overhead view) and (H) (cross-sectional view). The cross-sectional shape of each wafer substrate obtained was observed using a Hitachi, Ltd. electron microscope (S-4700) to check for the presence of voids (air gaps) within the resist underlayer film that filled the gaps between the lines. The results are shown in Table 4. When a resist underlayer film-forming composition with poor filling properties was used, voids occurred within the resist underlayer film that filled the gaps between the lines in this evaluation. When a resist underlayer film-forming composition with good filling properties was used, a void-free resist underlayer film 8 was filled within the gaps between the lines of the base substrate 7 having a dense line and space pattern, as shown in Figure 2(I).

[0177] Flatness evaluation: For a base substrate 9 (SiO2 wafer substrate) having a dense line and space pattern as shown in Figure 3(J), the cross-sectional shape of each wafer substrate obtained in the above-mentioned embedding characteristic evaluation as shown in Figure 3(K) was observed using a scanning electron microscope (SEM), and the step Delta 10 between the dense line pattern area and the non-line pattern area of ​​the resist underlayer film 10 was observed using an electron microscope (S-4700) manufactured by Hitachi, Ltd. In this evaluation, the smaller the step, the better the flattening characteristics. The results are shown in Table 4.

[0178] [Table 4]

[0179] As shown in Table 4, Examples 2-1 to 2-10, which used the resist underlayer film-forming compositions (UDL-1 to 10) of the present invention, were able to fill dense line and space patterns without generating voids, and were confirmed to have good filling properties. Furthermore, compared to Comparative Examples 2-1 and 2-2, which used Comparative Polymers R1 and R2, which are reported in JP 2021-084974 and JP 2021-138851 as polymers with excellent dry etching resistance during substrate processing, the film had a small step between the patterned and non-patterned portions, and was confirmed to have excellent planarization properties. Comparing Examples 2-1 to 2-4, Examples 2-3 and 2-4, which used polymers UDL-3 and UDL-4 having the structures of general formula (1A) and general formula (1B), respectively, showed superior flatness. This is thought to be due to the improved thermal fluidity of the polymers containing the structure of general formula (1B). Furthermore, when Example 2-8 and Example 2-10 were compared, Example 2-10 showed superior flatness, which is believed to be due to the improved thermal fluidity caused by the addition of the flow promoter (D-1).

[0180] [Evaluation of Etching Resistance (Examples 3-1 to 3-10, Comparative Examples 3-1 to 3-6)] The resist underlayer film-forming compositions (UDL-1 to 10 and comparative examples UDL-1 to 3, 5 to 7) that had a favorable solvent resistance rating were coated onto silicon substrates and heated at 350°C for 60 seconds using a hot plate to form resist underlayer films, and their film thicknesses a were measured. Etching was then performed using a Telius etching system manufactured by Tokyo Electron under the following conditions, with CF4 gas, to measure their film thickness b. The etching rate A (nm / min) was calculated as the film thickness etched per minute from the film thickness etched over a specified time using CF4 gas (film thickness a - film thickness b). Separately, substrates were prepared by heating at 350°C for 60 seconds, and heated at 500°C for 90 seconds in a nitrogen stream with an oxygen concentration controlled to 0.2% or less to form resist underlayer films, and their film thicknesses c were measured. Etching was then performed using a Telius etching system manufactured by Tokyo Electron under the following conditions, with CF4 gas, to measure their film thickness d. The etching rate B (nm / min) was calculated from the thickness of the film etched in 1 minute using CF4 gas (thickness c - thickness d). The smaller the etching rate, the better the etching resistance to CF4 gas. The etching resistance of the film fired at 500°C and the film fired at 350°C was compared, and the improvement in etching resistance due to firing at 500°C (etching rate A (nm / min) - etching rate B (nm / min)) was calculated. The etching conditions are as follows:

[0181] 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

[0182] [Table 5]

[0183] As shown in Table 5, in Examples 3-1 to 3-10, which used the resist underlayer film-forming compositions (UDL-1 to 10) of the present invention, the etching rate using CF4 gas for films baked at 350°C was 70 nm / min or less, demonstrating excellent etching resistance. Furthermore, the etching resistance of films baked at 500°C under a nitrogen stream with an oxygen concentration controlled to 0.2% or less was even better, with an etching rate improvement of 5 nm / min or more compared to films baked at 350°C. This is presumably because the resist underlayer film-forming compositions of the present invention are high-carbon materials that actively cause thermal decomposition of the cured film upon high-temperature baking, and therefore, when baked at 500°C under a nitrogen stream with an oxygen concentration controlled to 0.2% or less, decomposition and recombination of carbon bonds occurred, resulting in densification of the cured film. Comparing UDL-1, which uses polymer (A1) synthesized by cationic polymerization, and UDL-2, which uses polymer (A2) synthesized by radical polymerization, UDL-1 showed better etching resistance. This is presumably because radical polymerization introduces terminal structures containing heteroatoms other than carbon, such as oxygen and nitrogen, which deteriorate etching resistance, due to the radical initiator, but cationic polymerization does not have this drawback. Polymers with a fluorene skeleton are known to have excellent etching resistance during substrate processing. However, Comparative Example 3-1, which used Comparative Polymer R1, exhibited insufficient etching resistance in films baked at 350°C. It is believed that the ether chains in the polymer contributed to the deterioration of etching resistance. The combination of crosslinker and polyether used in the composition for forming a resist underlayer film of the present invention is reported in International Publication No. 2014 / 066268. While the invention described above is for a different application than resist underlayer films, if this composition were used for a resist underlayer film, it is expected that etching resistance would be insufficient for the same reasons as Comparative Example 3-1. Furthermore, Comparative Example UDL-3, which used Comparative Polymer R3, is believed to have inferior etching resistance compared to UDL-1 due to the inclusion of a polymer with hydroxyl groups. Based on the above, the composition for forming a resist underlayer film of the present invention must not contain oxygen atoms in the polymer, which would deteriorate etching resistance. On the other hand, Comparative Example 3-2, which uses Comparative Polymer R2, which is reported in JP 2021-138851 A as a polymer with excellent dry etching resistance during substrate processing, does not contain oxygen atoms that deteriorate etching resistance, and therefore the film baked at 350°C exhibits excellent etching resistance, but the improvement effect when baked at 500°C was small. This is presumably because Comparative Example UDL-2, unlike the composition for forming a resist underlayer film of the present invention, has excellent heat resistance, and therefore densification of the cured film was not promoted when baked at 500°C. Comparative Example UDL-5, in which the crosslinking agent was changed to XL-1, and Comparative Examples 3-4 to 3-6, in which Comparative Examples UDL-6 to 7 were used, each containing only a polymer having a structure represented by general formula (1B) (Comparative Polymers R4 and R5), showed insufficient etching resistance when baked at 350°C, and the improvement effect when baked at 500°C was also small. Comparative Example Polymers R4 and R5 are also polymers that actively undergo thermal decomposition when baked at high temperatures, but it is presumed that sublimation of low-molecular-weight components due to thermal decomposition became dominant, making it difficult for the cured film to be densified compared to Polymer (A1). That is, to form a resist underlayer film having excellent etching resistance, a combination of a polymer having a structure represented by general formula (1A) and a crosslinking agent having a structure represented by general formula (B-1) is required.

[0184] [Pattern Forming Method (Examples 4-1 to 4-10, Comparative Examples 4-1 to 4-6)] The resist underlayer film-forming compositions (UDL-1 to 10, Comparative Examples UDL-1 to 3, and Comparative Examples UDL-5 to 7) were each applied to a silicon wafer substrate with a SiO2 film having a trench pattern (trench width: 10 μm, trench depth: 0.10 μm) and baked in air at 350°C for 60 seconds. The substrate was then heated at 500°C for 90 seconds in a nitrogen stream with an oxygen concentration controlled to 0.2% or less to form a 100 nm thick resist underlayer film. A silicon-containing resist intermediate film material (SOG-1) was applied on top of the resist underlayer film and baked at 220°C for 60 seconds to form a 20 nm thick resist intermediate film. An ArF single-layer resist from the resist upper layer film material was then applied on top of the resist underlayer film and baked at 105°C for 60 seconds to form a 100 nm thick photoresist film. An immersion protective film material (TC-1) was applied onto the photoresist film and baked at 90°C for 60 seconds to form a protective film with a thickness of 50 nm.

[0185] The silicon-containing resist interlayer material (SOG-1) was prepared by dissolving a polymer designated as ArF silicon-containing interlayer polymer (SiP1) and a thermal crosslinking catalyst (CAT1) in an organic solvent containing 0.1 mass% of FC-4430 (manufactured by Sumitomo 3M) in the proportions shown in Table 6, and filtering the solution through a fluororesin filter with a pore size of 0.1 μm.

[0186] [Table 6]

[0187] The structural formulae of the ArF silicon-containing intermediate film polymer (SiP1) and thermal crosslinking catalyst (CAT1) used are shown below. [ka]

[0188] The resist top layer material (ArF single-layer resist) was prepared by dissolving a polymer (RP1), an acid generator (PAG1), and a basic compound (Amine1) in the proportions shown in Table 7 in a solvent containing 0.1 mass% of surfactant FC-4430 (Sumitomo 3M Limited), and filtering the solution through a 0.1 μm fluororesin filter.

[0189] [Table 7]

[0190] The polymer (RP1), acid generator (PAG1), and basic compound (Amine1) used in the resist top layer material (ArF single layer resist) are shown below. [ka]

[0191] The immersion protective film material (TC-1) was prepared by dissolving the protective film polymer (PP1) in an organic solvent in the ratio shown in Table 8 and filtering the solution through a 0.1 μm fluororesin filter.

[0192] [Table 8]

[0193] The protective film polymer (PP1) used in the immersion protective film material (TC-1) is shown below. [ka]

[0194] The resist was then exposed using an ArF immersion exposure system (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% by mass aqueous solution of tetramethylammonium hydroxide (TMAH) for 30 seconds to obtain a 55 nm 1:1 positive line-and-space pattern (resist upper layer film pattern).

[0195] Next, the resist intermediate film was dry-etched using a Tokyo Electron etching system, Telius, with the resist upper layer film pattern as a mask to form a resist intermediate film pattern, the resist underlayer film was etched using the resulting resist intermediate film pattern as a mask to form a resist underlayer film pattern, and the SiO2 film was etched using the resulting resist underlayer film pattern as a mask. The etching conditions are as follows:

[0196] Conditions for transferring the resist upper layer film pattern to the resist intermediate film. Chamber pressure: 50mT RF power (top): 500W RF power (bottom): 300W CF4 gas flow rate: 150sccm CHF3 gas flow rate: 50sccm Time: 15sec

[0197] Conditions for transferring the resist intermediate film 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

[0198] Transfer conditions for 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: 15 sccm O2 gas flow rate: 5sccm Time: 100sec

[0199] The cross section of the pattern was observed using an electron microscope (S-4700) manufactured by Hitachi, Ltd. The results are shown in Table 9. [Table 9]

[0200] As shown in Table 9, in Examples 4-1 to 4-10, which used the resist underlayer film-forming compositions (UDL-1 to 10) of the present invention, the resist upper layer film pattern was ultimately transferred successfully to the substrate in all cases, confirming that the resist underlayer film-forming compositions of the present invention are suitable for fine processing using a multilayer resist method, and the LWR after substrate processing was also good. On the other hand, in Comparative Examples UDL-1 to 3 and Comparative Examples UDL-5 to 7, which were confirmed to have insufficient etching resistance compared to the resist underlayer film-forming compositions of the present invention in the above etching resistance evaluation, the pattern shape after substrate transfer etching was vertical, but deterioration of the LWR after substrate processing was observed.

[0201] From the above, it has become clear that the composition for forming a resist underlayer film of the present invention has both high filling / planarization properties and dry etching resistance, 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 can form a fine pattern with high precision even if the workpiece is a substrate having steps, and that the resist underlayer film formation method of the present invention can form a resist underlayer film without voids even if the workpiece is a substrate having steps.

[0202] The present specification includes the following aspects. [1]: A composition for forming a resist underlayer film, comprising: (A) a polymer having a structure represented by the following general formula (1A); (B) a crosslinking agent having a structure represented by the following general formula (B-1); and (C) an organic solvent, wherein the (A) polymer does not contain a hydroxyl group; and the (B) crosslinking agent is contained in an amount of 5 to 50 parts by mass relative to 100 parts by mass of the (A) polymer. [ka] (In general formula (1A), R1 is any one of a hydrogen atom, a halogen atom, and a linear, branched, or cyclic hydrocarbon group having 1 to 20 carbon atoms.) [ka] (In general formula (B-1), W1 and W2 each independently represent a benzene ring or a naphthalene ring which may have a substituent, R2 each independently represent a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, and X is a group represented by the following formula (2).) [ka] (In formula (2), * indicates the bond position.) [2]: The composition for forming a resist underlayer film according to the above [1], further comprising a polymer having a partial structure represented by the following general formula (1B): [ka] (In general formula (1B), R'2, R3, and R4 each independently represent a hydrogen atom, a halogen atom, or a linear, branched, or cyclic hydrocarbon group having 1 to 20 carbon atoms.) [3]: The composition for forming a resist underlayer film according to the above [1] or [2], wherein the polymer (A) has a structure represented by the following general formula (1C): [ka] (In the general formula (1C), a, b, and c are in the ranges of a+b+c=1, 0.5≦a≦0.9, and 0.1≦b+c≦0.5, respectively.) [4]: The composition for forming a resist underlayer film according to any one of [1] to [3] above, wherein the weight average molecular weight Mw of the polymer (A) in terms of polystyrene as determined by gel permeation chromatography is 500 to 5,000. [5]: The composition for forming a resist underlayer film according to any one of [1] to [4] above, characterized in that the ratio Mw / Mn of the weight average molecular weight Mw and the number average molecular weight Mn of the crosslinking agent (B) in terms of polystyrene, as determined by gel permeation chromatography, is 1.00≦Mw / Mn≦1.25. [6]: The composition for forming a resist underlayer film according to any one of [1] to [5] above, characterized in that the composition contains (D) a fluidity 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. [7]: The composition for forming a resist underlayer film according to the above [6], wherein the (D) fluidity promoter comprises one or more compounds selected from the following general formulae (i) to (iii): [ka] (In general 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, and W 1 is a phenylene group or a divalent group represented by the following general formula (i-1), and W 2 and W 3 are each independently a single bond or a divalent group represented by the following formula (i-2), and m 1 is an integer between 1 and 10, and n 1 is an integer between 0 and 5.) [ka] (In general formula (i-1), * indicates a bonding position, and R 10 , R 11 , R12 , and R 13 are each independently a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms; W 10 and W 11 are each independently a single bond or a carbonyl group, and m 10 , m 11 is an integer between 0 and 10, and m 10 +m 11 ≧1.) [ka] (In formula (i-2), * indicates a bonding position.) [ka] (In general formula (ii), R 2 are each independently a hydrogen atom or an optionally substituted organic group having 1 to 10 carbon atoms, W 4 is a divalent group represented by the following general formula (ii-1), and W 5 is a single bond or a divalent group represented by the following formula (ii-2), and m 2 is an integer between 2 and 10, and n 3 is an integer between 0 and 5.) [ka] (In general formula (ii-1), * indicates a bonding position, and R 20 , R 21 , R 22 , and R 23 are each independently a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms, and m 20 , m 21 is an integer between 0 and 10, and m 20 +m 21 ≧1.) [ka] (In formula (ii-2), * indicates the bonding position.) [ka] (In general formula (iii), R3 and R 4 are each independently 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; R 5 and R 6 are each independently an organic group having 1 to 10 carbon atoms, and R 5 is a group containing either an aromatic ring or a divalent group represented by the following general formula (iii-1), and W 6 and W 7 is a single bond or a divalent group represented by the following formula (iii-2), and at least one of them is a divalent group represented by the following formula (iii-2). [ka] (In general formula (iii-1), * indicates a bonding position, and W 30 is an organic group having 1 to 4 carbon atoms. [ka] (In formula (iii-2), * indicates a bonding position.) [8]: The composition for forming a resist underlayer film according to any one of [1] to [7] above, characterized in that the composition further contains one or more of (E) a surfactant, (F) an acid generator, and (G) a plasticizer. [9]: A method for forming a pattern on a workpiece substrate, (I-1) A step of applying a composition for forming a resist underlayer film according to any one of the above [1] to [8] onto a substrate to be processed, followed by heat treatment 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 has been 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:

[10] : A method for forming a pattern on a workpiece substrate, (II-1) A step of applying a composition for forming a resist underlayer film according to any one of the above [1] to [8] onto a substrate to be processed, followed by heat treatment 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 pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern on the resist upper layer film; (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:

[11] : A method for forming a pattern on a workpiece substrate, (III-1) A step of applying a composition for forming a resist underlayer film according to any one of the above [1] to [8] onto a substrate to be processed, followed by heat treatment 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 it with a developer to form a pattern on the resist upper layer film; (III-6) a step of transferring the 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) 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:

[12] : The pattern forming method according to any one of [9] to

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

[13] : 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 resist underlayer film-forming composition according to any one of [1] to [8] above onto a substrate to be processed, and heat-treating the substrate coated with the resist underlayer film-forming composition at a temperature of 100°C or higher and 800°C or lower for 10 to 600 seconds to form a cured film.

[14] : 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 resist underlayer film-forming composition according to any one of [1] to [8] above onto a substrate to be processed, and heat-treating the substrate coated with the resist underlayer film-forming composition in an atmosphere having an oxygen concentration of 1% or more and 21% or less to form a cured film.

[15] : 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 resist underlayer film-forming composition according to any one of [1] to [8] above onto a substrate to be processed, and heat-treating the substrate coated with the resist underlayer film-forming composition in an atmosphere with an oxygen concentration of less than 1%, thereby forming a cured film.

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

[13] to

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

[0203] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits similar effects is included within the technical scope of the present invention. [Explanation of symbols]

[0204] 1...Substrate to be processed, 2...Layer to be processed, 2a...pattern (pattern formed on the processing layer), 3...resist underlayer film, 3a...resist underlayer film pattern, 4...resist intermediate film, 4a...resist intermediate film pattern, 5...resist upper layer film, 5a...resist upper layer film pattern, 6...exposed portion, 7...Base substrate having dense line and space pattern, 8...Resist underlayer film, 9...Base substrate having dense line and space pattern, 10...Resist underlayer film, Delta10: Step difference between the dense line pattern area and the non-line pattern area of ​​the resist underlayer film.

Claims

1. A composition for forming a resist underlayer film, comprising: (A) a polymer having a structure represented by the following general formula (1A); (B) a crosslinking agent having a structure represented by the following general formula (B-1); and (C) an organic solvent, wherein the polymer (A) does not contain a hydroxyl group; and the content of the crosslinking agent (B) is 5 to 50 parts by mass relative to 100 parts by mass of the polymer (A): 【Chemistry 1】 (In general formula (1A), R １ is a hydrogen atom, a halogen atom, or a linear, branched, or cyclic hydrocarbon group having 1 to 20 carbon atoms. 【Chemistry 2】 (In general formula (B-1), W １ and W ２ are each independently a benzene ring or a naphthalene ring which may have a substituent, and R ２ each independently represents a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, and X is a group represented by the following formula (2): 【Transformation 3】 (In formula (2), * indicates a bonding position.)

2. 2. The composition for forming a resist underlayer film according to claim 1, further comprising a polymer having a partial structure represented by the following general formula (1B): 【Chemistry 4】 (In general formula (1B), R' ２ , R ３ , and R ４ are each independently a hydrogen atom, a halogen atom, or a linear, branched, or cyclic hydrocarbon group having 1 to 20 carbon atoms.

3. 2. The composition for forming a resist underlayer film according to claim 1, wherein the polymer (A) has a structure represented by the following general formula (1C): 【Transformation 5】 (In general formula (1C), a, b, and c are in the ranges of a+b+c=1, 0.5≦a≦0.9, and 0.1≦b+c≦0.5, respectively.)

4. 2. The composition for forming a resist underlayer film according to claim 1, wherein the polymer (A) has a weight average molecular weight Mw of 500 to 5,000 in terms of polystyrene as determined by gel permeation chromatography.

5. 2. The composition for forming a resist underlayer film according to claim 1, wherein the ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight Mn of the crosslinking agent (B) in terms of polystyrene, as determined by a gel permeation chromatography method, is 1.00≦Mw / Mn≦1.

25.

6. 2. The composition for forming a resist underlayer film according to claim 1, wherein the composition contains (D) a fluidity promoter whose weight loss rate at temperatures from 30°C to 190°C is less than 30% and whose weight loss rate at temperatures from 30°C to 350°C is 98% or more.

7. 7. The composition for forming a resist underlayer film according to claim 6, wherein the fluidity promoter (D) comprises one or more compounds selected from the following general formulas (i) to (iii): 【Transformation 6】 (In general formula (i), R １ are each independently a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms which may be substituted; W １ is a phenylene group or a divalent group represented by the following general formula (i-1), W ２ and W ３ are each independently a single bond or a divalent group represented by the following formula (i-2), and m １ is an integer from 1 to 10, and n １ is an integer from 0 to 5. 【Transformation 7】 (In general formula (i-1), * indicates a bonding position, and R １０ , R １１ , R １２ , and R １３ are each independently a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms; W １０ and W １１ are each independently a single bond or a carbonyl group, and m １０ , m １１ is an integer from 0 to 10, and m １０ +m １１ ≧1.) 【Transformation 8】 (In formula (i-2), * indicates a bonding position.) 【Chemistry 9】 (In general formula (ii), R ２ are each independently a hydrogen atom or an optionally substituted organic group having 1 to 10 carbon atoms, W ４ is a divalent group represented by the following general formula (ii-1), and W ５ is a single bond or a divalent group represented by the following formula (ii-2), and m ２ is an integer from 2 to 10, and n ３ is an integer from 0 to 5. 【Chemistry 10】 (In general formula (ii-1), * indicates a bonding position, and R ２０ , R ２１ , R ２２ , and R ２３ are each independently a hydrogen atom, a hydroxyl group, or an organic group having 1 to 10 carbon atoms, and m ２０ , m ２１ is an integer from 0 to 10, and m ２０ +m ２１ ≧1.) 【Chemistry 11】 (In formula (ii-2), * indicates the bonding position.) 【Chemistry 12】 (In general formula (iii), R ３ and R ４ are each independently 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; R ５ and R ６ are each independently an organic group having 1 to 10 carbon atoms, and R ５ is a group containing either an aromatic ring or a divalent group represented by the following general formula (iii-1), and W ６ and W ７ is a single bond or a divalent group represented by the following formula (iii-2), and at least one of them is a divalent group represented by the following formula (iii-2): 【Chemistry 13】 (In general formula (iii-1), * indicates a bonding position, W ３０ is an organic group having 1 to 4 carbon atoms. 【Chemistry 14】 (In formula (iii-2), * indicates the bonding position.)

8. 2. The composition for forming a resist underlayer film according to claim 1, further comprising at least one of (E) a surfactant, (F) an acid generator, and (G) a plasticizer.

9. A method for forming a pattern on a workpiece substrate, comprising: (I-1) a step of applying the composition for forming a resist underlayer film according to any one of claims 1 to 8 onto a substrate to be processed, followed by heat treatment 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 has been 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:

10. A method for forming a pattern on a workpiece substrate, comprising: (II-1) A step of applying the composition for forming a resist underlayer film according to any one of claims 1 to 8 onto a substrate to be processed, followed by heat treatment 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 pattern-exposing the resist upper layer film and then developing it with a developer to form a pattern on the resist upper layer film; (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:

11. A method for forming a pattern on a workpiece substrate, comprising: (III-1) A step of applying the composition for forming a resist underlayer film according to any one of claims 1 to 8 onto a substrate to be processed, followed by heat treatment 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 it with a developer to form a pattern on the resist upper layer film; (III-6) a step of transferring the 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) transferring the 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:

12. 10. The pattern forming method according to claim 9, wherein the substrate to be processed has a structure or step having a height of 30 nm or more.

13. 10. 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 the composition for forming a resist underlayer film according to any one of claims 1 to 8 onto a substrate to be processed, and heat-treating the substrate coated with the composition for forming a resist underlayer film at a temperature of 100°C or higher and 800°C or lower for 10 to 600 seconds to form a cured film.

14. 10. A method for forming a resist underlayer film that functions as an organic flat film used in a manufacturing process of a semiconductor device, the method comprising spin-coating the composition for forming a resist underlayer film according to claim 1 onto a substrate to be processed, and heat-treating the substrate coated with the composition for forming a resist underlayer film in an atmosphere having an oxygen concentration of 1% or more and 21% or less, thereby forming a cured film.

15. 10. A method for forming a resist underlayer film that functions as an organic flat film used in a manufacturing process of a semiconductor device, the method comprising spin-coating the composition for forming a resist underlayer film according to claim 1 onto a substrate to be processed, and heat-treating the substrate coated with the composition for forming a resist underlayer film in an atmosphere with an oxygen concentration of less than 1%, thereby forming a cured film.

16. 14. The method for forming a resist underlayer film according to claim 13, wherein the substrate to be processed has a structure or step having a height of 30 nm or more.

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