Resist underlayer film forming method and pattern forming method

Abstract

The present invention relates to a method for forming a resist underlayer film and a method for forming a pattern, which exhibit excellent dry etching resistance and film thickness uniformity by plasma irradiation. The resist underlayer film forming method includes (i) a step of applying a composition containing (A) a polymer and (B) an organic solvent and performing heat treatment; (ii) a step for forming a resist underlayer film by plasma irradiation, the polymer (A) containing a structural unit represented by formula (1) and having a weight-average molecular weight of 2500-20000; in the formula (1), Ar1 and Ar2 are benzene rings or naphthalene rings, X is a structure of formula (1A), Y is an organic group, and k is 0 or 1. In the formula (1A), n1 is 0 or 1, n2 is 1 or 2, and R2 is a hydrogen atom, an organic group or a structure of formula (1B). R3 represents a hydrogen atom, an alkyl group, an aryl group, or a group represented by formula (1C), and n3 represents 0-2. In formula (1B), RA is an organic group, and RB is a hydrogen atom or an organic group. In formula (1C), R4 represents a hydrogen atom or a hydrocarbon group. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to a resist underlayer film forming method applicable to fine patterning by a multilayer resist method in a semiconductor device manufacturing process, and a pattern forming method using the resist underlayer film. Background Art

[0002] With the high integration and high speed of LSI, the pattern size is being miniaturized rapidly. With this miniaturization, photolithography technology realizes the formation of fine patterns by shortening the wavelength of the light source and appropriately selecting the resist composition. The focus is on the positive photoresist composition used in the form of a single layer. The single-layer positive photoresist composition has a skeleton with etching resistance to dry etching based on chlorine or fluorine gas plasma in the resist resin, and has a switching mechanism such that the exposed part dissolves, so that the exposed part dissolves to form a pattern, and the residual resist pattern is used as an etching mask to perform dry etching processing on the processed substrate.

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

[0004] On the other hand, in the processing of the processed substrate, a method of processing the substrate by dry etching is usually used to form a photoresist film with a pattern as an etching mask, but in reality, there is no dry etching method that can obtain complete etching selectivity between the photoresist film and the processed substrate. Therefore, there is the following problem: in the processing of the substrate, the photoresist film is also damaged and collapsed, and the resist pattern cannot be accurately transferred to the processed substrate. Therefore, with the miniaturization of the pattern, a higher dry etching resistance is required for the resist composition. However, on the other hand, in order to improve the definition, for the resin used in the photoresist composition, a resin with small light absorption under the exposure wavelength is required. Therefore, as the exposure light is i-ray, KrF, ArF and the wavelength is shortened, the resin is also changed to a novolac resin, polyhydroxystyrene, and a resin with an aliphatic polycyclic skeleton, but in reality, the etching speed under the dry etching conditions during substrate processing gradually becomes faster, and the current photoresist composition with high definition has a tendency to weaken etching resistance.

[0005] Therefore, it is necessary to perform dry etching processing on the substrate to be processed using a thinner photoresist film with weaker etching resistance, and ensuring the materials and process in this processing step has become a top priority.

[0006] As one of the methods to solve this problem, there is a multilayer resist method. This method is as follows: a resist intermediate film having an etching selectivity different from that of a photoresist film (i.e., a resist upper film) is sandwiched between the resist upper film and a substrate to be processed, and after the resist upper film is patterned, the resist upper film pattern is used as a dry etching mask to transfer the pattern to the resist intermediate film by dry etching, and further, the resist intermediate film is used as a dry etching mask to transfer the pattern to the substrate to be processed by dry etching.

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

[0008] On the other hand, in recent years, the miniaturization of DRAM memory has been accelerating, and the need for further improvement of dry etching resistance and resist underlayer films with excellent filling and planarization characteristics has gradually increased. As coating-type organic underlayer film materials with excellent filling and planarization characteristics, for example, the material described in Patent Document 2 has been reported, but when considering the application in the next generation, there are concerns about dry etching resistance, and the application of existing coating-type organic underlayer film materials is approaching the limit.

[0009] In response to the above-mentioned problems, Patent Document 3 reports that the etching resistance of the substrate during processing is improved by performing additional treatments of plasma irradiation and electron beam irradiation on the resist lower film. It can be considered that by performing the above-mentioned additional treatment, the chemical bonding of the hydrocarbon-containing film is separated and re-bonded, and it is reconstructed in the form of a solidified film having a diamond-like carbon structure, which helps to increase the hardness and density. However, it can be predicted that the film thickness change caused by the above-mentioned additional treatment of the resist lower film used in the above-mentioned embodiment is as large as 100nm or more, and the uniformity of the film thickness after the additional treatment is also insufficient. In the case of a filling film for a processed substrate with a height difference, it is considered that there is the possibility that the flatness may be deteriorated due to the influence of the film shrinkage caused by plasma irradiation and electron beam irradiation; during the process of plasma irradiation and electron beam irradiation, there is the possibility that pores may be generated in the filling film due to excessive scattering of the solid components in the film. Therefore, it is considered that a method for forming a resist lower film with a small film thickness change before and after plasma irradiation is needed.

[0010] Prior art literature

[0011] Patent Literature

[0012] Patent Document 1: Japanese Patent Application Publication No. 2004-205685

[0013] Patent Document 2: Japanese Patent No. 6714493

[0014] Patent Document 3: Japanese Patent Application Publication No. 2020-183506 Summary of the invention

[0015] Problem that the invention aims to solve

[0016] The present invention is made in view of the above situation, and its purpose is to provide a method for forming an anti-etching underlayer film that exhibits extremely excellent dry etching resistance and excellent film thickness uniformity for existing organic underlayer film materials by plasma irradiation, and a pattern forming method using the anti-etching underlayer film.

[0017] Solutions for solving problems

[0018] In order to solve the above-mentioned problems, the present invention provides a method for forming a resist underlayer film, which is a method for forming a resist underlayer film on a substrate, comprising the following steps:

[0019] (i) a step of coating a resist underlayer film-forming composition comprising (A) a polymer and (B) an organic solvent on the substrate, and curing the composition by heat treatment at a temperature of 100° C. to 800° C. for 10 seconds to 7,200 seconds to form an underlayer film precursor film; and

[0020] (ii) a step of irradiating the substrate on which the underlayer film precursor film is formed with plasma to form a resist underlayer film,

[0021] The polymer (A) includes a structural unit represented by the following general formula (1), and has a polystyrene-equivalent weight average molecular weight of 2,500 to 20,000 based on gel permeation chromatography.

[0022]

[0023] (In the formula, Ar1 and Ar2 are independently substituted or unsubstituted benzene rings or substituted or unsubstituted naphthalene rings, X is a structure represented by the following general formula (1A), Y is a divalent organic group having 6 to 50 carbon atoms, and k is 0 or 1.)

[0024]

[0025] (In the formula, n1 is 0 or 1, n2 is 1 or 2, R2 is a hydrogen atom, an organic group having 1 to 10 carbon atoms, or any one of the structures represented by the following general formula (1B). R3 is a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a group represented by the following general formula (1C), n3 is 0, 1 or 2, * is a bonding portion bonded to a methylene group, and ** is a bonding portion bonded to a quaternary carbon of fluorene.)

[0026]

[0027] (where * represents the bonding site to the oxygen atom, R A is a divalent organic group having 1 to 10 carbon atoms, R B It is a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms.

[0028]

[0029] (In the formula, R4 is a hydrogen atom or a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms, and the hydrogen atoms on the benzene ring in the formula may be optionally replaced by a methyl group or a methoxy group.)

[0030] According to the resist underlayer film forming method, the structure including the fluorene skeleton with high carbon density is repeatedly bonded by the methylene group, so that the film is easily modified by plasma irradiation, and a resist underlayer film with excellent dry etching resistance can be provided. In addition, by including the crosslinking group structure containing oxygen atoms and the methylene group, the curability, density and heat resistance of the resist underlayer film are improved, and the scattering of the solid components in the film caused by plasma irradiation can be alleviated. Therefore, the film thickness change before and after plasma irradiation is small, and a resist underlayer film with high film thickness uniformity and dry etching resistance can be formed.

[0031] In the general formula (1), Y is preferably any one of the structures represented by the following formula (Y-1).

[0032]

[0033]

[0034] (The hydrogen atoms in the above structure may be substituted with a hydroxyl group or a monovalent organic group having 1 to 10 carbon atoms.)

[0035] According to such a resist underlayer film forming method, the film is easily modified by plasma irradiation, and a resist underlayer film having excellent dry etching resistance can be provided.

[0036] In the above general formula (1A), R2 is preferably a hydrogen atom.

[0037] Such a resist underlayer film forming method can provide a resist underlayer film having excellent substrate adhesion after plasma irradiation, and is also preferred because it contributes to high film density.

[0038] In addition, in the general formula (1A), R2 is a hydrogen atom or a structure represented by the general formula (1B). Among the structures constituting the above R2, when the proportion of hydrogen atoms is set to a and the proportion of the structure represented by the general formula (1B) is set to b, it is preferred to satisfy the relationship of a+b=1 and 0.1≤b≤0.9.

[0039] Such a resist underlayer film forming method can provide a resist underlayer film having excellent substrate adhesion after plasma irradiation. In addition, since a polymer having excellent fluidity is formed, a resist underlayer film forming method having excellent planarization characteristics can be provided.

[0040] In addition, it is preferred that: in the aforementioned general formula (1), Ar1 and Ar2 are unsubstituted benzene rings, and in the aforementioned general formula (1A), n1 is 0, n2 is 1 or 2, and n3 is 0.

[0041] If this resist underlayer film forming method is used, the film is easily modified by plasma irradiation, and a resist underlayer film with excellent dry etching resistance can be provided. In addition, since a polymer with excellent fluidity is formed, a resist underlayer film forming method with excellent planarization characteristics can be provided.

[0042] In the above general formula (1), k is preferably 0.

[0043] According to such a resist underlayer film forming method, a polymer having excellent solvent solubility is formed, so that the storage stability of the resist underlayer film forming composition is improved, and a resist underlayer film forming method having excellent practicality can be provided.

[0044] The (A) polymer preferably has a polystyrene-equivalent weight average molecular weight of 7,000 to 15,000 as determined by gel permeation chromatography.

[0045] If this method is used to form a resist underlayer film, the curability, density and heat resistance of the resist underlayer film are improved, and the scattering of solid components in the film caused by plasma irradiation can be alleviated. Therefore, a resist underlayer film with high film thickness uniformity and dry etching resistance can be formed.

[0046] Furthermore, the resist underlayer film-forming composition preferably further contains one or more of (C) a crosslinking agent, (D) a surfactant, (E) an acid generator, and (F) a plasticizer.

[0047] By using the resist underlayer film-forming composition containing the above additives, various properties required for forming a resist underlayer film, such as coating properties, film thickness uniformity, dry etching resistance, and filling / planarization characteristics, can be adjusted within appropriate ranges.

[0048] The (B) organic solvent is preferably a mixture of one or more organic solvents having a boiling point of less than 180 degrees and one or more organic solvents having a boiling point of 180 degrees or more, that is, (B-1) a high boiling point solvent.

[0049] By using the resist underlayer film-forming composition containing such a component (B), a resist underlayer film having excellent planarization characteristics can be formed.

[0050] In the step (ii), the plasma irradiation is preferably performed in an atmosphere of N2, NF3, H2, fluorocarbon, rare gas or a mixture of any of them.

[0051] By using plasma irradiation as the curing method for the resist underlayer film, a resist underlayer film having excellent dry etching resistance compared with a curing method using only heating can be provided.

[0052] In the step (i), the heat treatment is preferably performed in an atmosphere having an oxygen concentration of 1% to 21%.

[0053] This method can activate the reaction sites of the resin in the resist underlayer film, and promote the curing reaction by plasma irradiation.

[0054] In the step (i), the heat treatment is preferably performed in an atmosphere having an oxygen concentration of less than 1%.

[0055] This method is useful because it can activate the reaction sites of the polymer in the resist underlayer film and promote the curing reaction based on plasma irradiation, without causing degradation of the processed substrate even when the processed substrate contains a raw material that is unstable to heating in an oxygen atmosphere.

[0056] In addition, the present invention provides a pattern forming method, which is a method for forming a pattern on a processed substrate, comprising the following steps:

[0057] (I-1) a step of forming a resist underlayer film on a substrate to be processed by the resist underlayer film forming method described above;

[0058] (I-2) a step of forming a resist intermediate film on the resist underlayer film;

[0059] (I-3) a step of forming a resist upper layer film on the resist intermediate film using a photoresist material;

[0060] (I-4) a step of exposing the resist upper layer film to pattern exposure and then developing the resist upper layer film with a developer to form a pattern on the resist upper layer film;

[0061] (I-5) a step of transferring the pattern to the resist intermediate film by dry etching using the resist upper layer film having the pattern as a mask;

[0062] (I-6) a step of transferring the pattern to the resist underlayer film by dry etching using the resist intermediate film to which the pattern is transferred as a mask; and

[0063] (I-7) A step of processing the substrate to be processed using the resist underlayer film having the pattern formed thereon as a mask to form a pattern on the substrate to be processed.

[0064] The above-mentioned pattern forming method can form a fine pattern on a workpiece with high precision.

[0065] In addition, the present invention provides a pattern forming method, which is a method for forming a pattern on a processed substrate, comprising the following steps:

[0066] (II-1) a step of forming a resist underlayer film on a substrate to be processed having a height difference by the resist underlayer film forming method described above;

[0067] (II-2) forming a resist upper layer film on the upper layer of the resist lower layer film;

[0068] (II-3) a step of exposing the resist upper layer film to pattern exposure and then developing the resist upper layer film with a developer to form a pattern on the resist upper layer film;

[0069] (II-4) a step of transferring the pattern to the resist lower film by dry etching using the resist upper film having the pattern formed thereon as a mask;

[0070] (II-5) A step of processing the substrate to be processed using the resist underlayer film having the pattern formed thereon as a mask to form a pattern on the substrate to be processed.

[0071] The above-mentioned pattern forming method can form a fine pattern on a workpiece with high precision.

[0072] In this case, it is preferable that the aspect ratio of the height difference of the substrate to be processed is set to 3 or more.

[0073] The pattern forming method of the present invention can form a resist underlayer film having high filling / planarization properties, and is therefore particularly useful in microfabrication of such a substrate having a structure or a step.

[0074] Effects of the Invention

[0075] As described above, the resist lower film forming method and pattern forming method of the present invention are particularly suitable for multilayer resist processes including embedding / planarization of processed substrates with height differences and concave-convex surfaces, and are extremely useful in the fine patterning for manufacturing semiconductor devices. In particular, in the fine patterning process using the multilayer resist method in the semiconductor device manufacturing process, even on the processed substrate with a dense portion of a fine pattern structure with a high aspect ratio represented by a gradually miniaturized DRAM memory, which is difficult to embed / planarize, it is possible to embed without producing defects such as pores and peeling, and a resist lower film with excellent flat characteristics can be formed. In addition, the existing resist lower film forming method shows excellent etching resistance and film thickness uniformity, especially by plasma irradiation, so that its effect can be exerted. Therefore, a fine pattern can be formed on the processed body with higher precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] Figure 1 It is an explanatory diagram of an example (three-layer resist process) of the pattern forming method of the present invention.

[0077] Figure 2 This is a diagram for explaining the landfill characteristics evaluation method.

[0078] Figure 3 This is a diagram for explaining the method of evaluating the planarization characteristics.

[0079] Description of Reference Numerals

[0080] 1 ... supporting substrate, 1A ... substrate to be processed, 2 ... processed layer,

[0081] 2a ... pattern (pattern formed on the processed layer), 3 ... resist underlayer film,

[0082] 3a... resist lower layer film pattern, 4... resist intermediate film,

[0083] 4a... resist intermediate film pattern, 5... resist upper film,

[0084] 5a…resist upper film pattern, 6…exposed portion,

[0085] 7…Base substrate with dense lines & spaces, 8…Resist underlayer film,

[0086] 9…Base substrate with dense lines and spaces, 10…Resist underlayer film,

[0087] Delta10: height difference of the resist underlayer film 10 between the pattern portion and the non-pattern portion. DETAILED DESCRIPTION

[0088] As described above, there is a demand for the development of a resist underlayer film forming method capable of transferring a resist pattern to a substrate to be processed with higher accuracy in a fine patterning process using a multilayer resist method, and a pattern forming method using the resist underlayer film.

[0089] Patent Document 3 reports that plasma irradiation improves the dry etching resistance of the resist underlayer film during substrate processing. It is speculated that plasma irradiation separates and rebonds the carbon bonds of the resist underlayer film, reconstructing the film in the form of a solidified film having a diamond-like carbon structure, thereby contributing to an increase in hardness and density.

[0090] On the other hand, it is believed that the resist underlayer film forming composition used in the embodiment of Patent Document 3 may be due to the use of oligomers with a molecular weight of less than 1,100, and the curability of the resist underlayer film before the additional treatment is insufficient, and not only the separation and rebonding of carbon bonds are carried out, but also the scattering of solid components in the film is actively caused. In the above embodiment, the film thickness change caused by the plasma irradiation treatment is as large as more than 100nm, and it can be predicted that the film thickness uniformity of the resist underlayer film after plasma irradiation is also insufficient. In the case of a filling film for a processed substrate with a height difference, there may be the following possibilities: the possibility of deterioration of flatness due to the influence of film shrinkage caused by plasma irradiation and electron beam irradiation; the possibility of excessive scattering of solid components in the film during plasma irradiation and electron beam irradiation, resulting in pores in the filling film. Therefore, it is believed that a resist underlayer film forming method with a small film thickness change before and after plasma irradiation is required.

[0091] The present inventors have conducted intensive studies in search of a resist underlayer film forming method that can achieve both high dry etching resistance and film thickness uniformity. As a result, it was found that: if it is the following resist underlayer film forming method, the resist underlayer film forming method is characterized in that it includes the following steps: a step of applying a resist underlayer film forming composition and curing it by heat treatment at a temperature of not less than 100°C and not more than 800°C for 10 seconds to 7,200 seconds to form an underlayer film precursor film; and a step of plasma irradiating the substrate on which the above-mentioned underlayer film precursor film is formed to form a resist underlayer film (cured film), wherein the resist underlayer film forming composition is characterized in that it contains (A) a polymer containing a structural unit represented by general formula (1) and (B) an organic solvent, and the weight average molecular weight of the above-mentioned (A) polymer in terms of polystyrene conversion based on gel permeation chromatography is 2,500 to 20,000; then, compared with the conventional resist underlayer film forming method based on plasma irradiation, the film thickness change before and after plasma irradiation is small, and a resist underlayer film showing excellent dry etching resistance and film thickness uniformity can be formed, thereby completing the present invention.

[0092] Hereinafter, the present invention will be described in detail, but the present invention is not limited to these.

[0093] <Resist Underlayer Film Formation Method>

[0094] The present invention is a method for forming a resist underlayer film, which is a method for forming a resist underlayer film on a substrate, comprising the following steps: (i) a step of forming an underlayer film precursor film by coating a resist underlayer film forming composition comprising (A) a polymer and (B) an organic solvent on the aforementioned substrate, and curing the composition by heat treatment at a temperature of not less than 100° C. and not more than 800° C. for 10 seconds to 7,200 seconds; and (ii) a step of forming a resist underlayer film by plasma irradiation of the substrate on which the aforementioned underlayer film precursor film is formed, wherein the aforementioned (A) polymer comprises a structural unit represented by the following general formula (1) and has a weight average molecular weight of 2,500 to 20,000 in terms of polystyrene based on gel permeation chromatography.

[0095]

[0096] (In the formula, Ar1 and Ar2 are independently substituted or unsubstituted benzene rings or substituted or unsubstituted naphthalene rings, X is a structure represented by the following general formula (1A), Y is a divalent organic group having 6 to 50 carbon atoms, and k is 0 or 1.)

[0097]

[0098] (In the formula, n1 is 0 or 1, n2 is 1 or 2, R2 is a hydrogen atom, an organic group having 1 to 10 carbon atoms, or any one of the structures represented by the following general formula (1B). R3 is a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a group represented by the following general formula (1C), n3 is 0, 1 or 2, * is a bonding portion bonded to a methylene group, and ** is a bonding portion bonded to a quaternary carbon of fluorene.)

[0099]

[0100] (where * represents the bonding site to the oxygen atom, R A is a divalent organic group having 1 to 10 carbon atoms, R B It is a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms.

[0101]

[0102] (In the formula, R4 is a hydrogen atom, or a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms, and the hydrogen atoms on the benzene ring in the formula may be substituted with a methyl group or a methoxy group.)

[0103] The method for applying the resist underlayer film-forming composition in the step (i) is not particularly limited. The resist underlayer film-forming composition will be described in detail later.

[0104] In the above step (i), the heat treatment (baking) temperature of the coating film is set to a temperature of 100° C. to 800° C., more preferably 150° C. to 600° C., further preferably 150° C. to 400° C., further preferably 200° C. to 350° C. The baking time is set to a range of 10 seconds to 7,200 seconds, further preferably 30 seconds to 600 seconds.

[0105] By appropriately adjusting the baking temperature and time within the above range, it is possible to obtain planarization / burying characteristics suitable for the application, as well as curing characteristics such as dry etching resistance and heat resistance. By performing heat treatment (baking) in a temperature range of more than 150°C and less than 400°C, a state in which a large number of active points for separation and rebonding of carbon bonds in the lower film precursor film are present in the film is presented, which easily promotes film modification based on plasma irradiation, and thus, a resist lower film with excellent dry etching resistance can be formed. At a baking temperature of more than 100°C, the residual solvent in the film can be reduced, and the degradation of the film thickness uniformity caused by plasma irradiation can be suppressed. If the baking temperature is set to less than 800°C, the thermal decomposition of the base resin can be suppressed, and a resist lower film with a small amount of sublimates can be provided. The heat treatment can also be performed in multiple times (stage baking).

[0106] In the step (i) above, the heat treatment may be performed in an atmosphere having an oxygen concentration of 1% to 21%.

[0107] By this method, the reaction sites of the resin in the resist underlayer film precursor film can be activated, and the curing reaction by plasma irradiation can be promoted.

[0108] Alternatively, in the step (i) above, the heat treatment may be performed in an atmosphere having an oxygen concentration of less than 1%.

[0109] As the baking atmosphere, any of an oxygen-containing atmosphere such as air (oxygen concentration is 1% to 21%) and a non-oxygen atmosphere such as nitrogen can be selected as needed. For example, when the substrate to be processed is easily oxidized by air, a cured film can be formed by heat treatment in an atmosphere with an oxygen concentration of less than 1%, thereby suppressing damage to the substrate.

[0110] Plasma irradiation can be performed by a known method, for example, the method described in Japanese Patent No. 5746670, "Improvement of the wiggling profile of spin-on carbon hard mask by H2 plasma treatment" (J. Vac. Sci. Technol. B26 (1), Jan / Feb 2008, p67-71).

[0111] The RF discharge power is preferably 100 to 10,000W, more preferably 500 to 5,000W.

[0112] As the gas atmosphere, for example, rare gases such as N2, NF3, H2, and He, and fluorocarbon compounds can be listed; more preferably, He, Ar, N2, Ne, NF3, H2, CF4, CHF3, CH2F2, CH3F, C4F6, C4F8, etc. can be listed. Two or more of these gases can be used in combination. It is an advantage of the present invention that the effect of the present invention can be expected even when a gas atmosphere containing no O2 is used.

[0113] The plasma irradiation time can be selected from, for example, 10 to 240 seconds, and the pressure can be appropriately selected.

[0114] In the above step (ii), the plasma irradiation is preferably carried out in an atmosphere of a rare gas such as N2, NF3, H2, fluorocarbons, He, or a mixture of any of them.

[0115] From the viewpoint of productivity, particularly preferred gas atmospheres include He, Ar, N 2 , and H 2 .

[0116] After plasma irradiation, the resist lower film may be subjected to heat treatment. When heating is performed after plasma irradiation, as heating conditions, the heating temperature may be appropriately selected from the range of 80 to 800° C. (preferably from 100 to 700° C., more preferably from 200 to 600° C.), and the heating time may be appropriately selected from the range of 30 to 180 seconds (preferably from 30 to 120 seconds). Although not bound by theory, it can be considered that by performing high-temperature heating after plasma irradiation, the dangling bonds are bonded, which can contribute to the high density of the cured film (resist lower film).

[0117] As the atmosphere for heating after plasma irradiation, any of an oxygen-containing atmosphere such as air (oxygen concentration is 1% to 21%) and a non-oxygen atmosphere such as nitrogen can be selected as needed. For example, in the case where the substrate to be processed is easily oxidized by air, a cured film can be formed by heat treatment in an atmosphere with an oxygen concentration of less than 1%, thereby suppressing damage to the substrate.

[0118] The irradiation device is not particularly limited as long as it can perform plasma irradiation, and for example, Telius SP and Tactras Vigus manufactured by Tokyo Electron Limited can be used. The device can be selected and the conditions can be set so that the effects of the present invention can be more significantly exhibited.

[0119] In the pattern forming method of the present invention using the resist underlayer film forming composition described in detail below, it is preferred to use a substrate to be processed having a structure or height difference with an aspect ratio of more than 3 or a height of 30nm. The resist underlayer film forming composition used in the present invention has excellent filling / planarization characteristics, so even if the substrate to be processed has a structure or height difference (concave-convex) with an aspect ratio of more than 3 or a height of more than 30nm, a flat resist underlayer film (cured film) can be formed. The aspect ratio of the structure possessed by the above-mentioned processed body substrate is preferably more than 3, and the aspect ratio is more preferably more than 5. The height of the structure or height difference possessed by the above-mentioned processed body substrate is preferably more than 30nm, more preferably more than 50nm, and more preferably more than 100nm. In the method for processing a height difference substrate having a pattern with the above-mentioned aspect ratio and the above-mentioned height, a resist underlayer film is formed by utilizing the resist underlayer film formation method of the present invention for filling / flattening, thereby enabling the film thickness of the resist intermediate film and the resist upper film formed thereafter to be uniform. Therefore, it is easy to ensure the exposure depth margin (DOF) during lithography, which is very preferred.

[0120] <Resist Underlayer Film-Forming Composition>

[0121] The resist underlayer film forming method of the present invention is characterized by using a resist underlayer film forming composition comprising (A) a polymer and (B) an organic solvent, wherein the (A) polymer comprises a structural unit of the following general formula (1) and has a polystyrene-equivalent weight average molecular weight of 2,500 to 20,000 based on gel permeation chromatography.

[0122]

[0123] (In the formula, Ar1 and Ar2 are independently substituted or unsubstituted benzene rings or substituted or unsubstituted naphthalene rings, X is a structure represented by the following general formula (1A), Y is a divalent organic group having 6 to 50 carbon atoms, and k is 0 or 1.)

[0124]

[0125] (In the formula, n1 is 0 or 1, n2 is 1 or 2, R2 is a hydrogen atom, an organic group having 1 to 10 carbon atoms, or any one of the structures represented by the following general formula (1B). R3 is a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a group represented by the following general formula (1C), n3 is 0, 1 or 2, * is a bonding portion bonded to a methylene group, and ** is a bonding portion bonded to a quaternary carbon of fluorene.)

[0126]

[0127] (where * represents the bonding site to the oxygen atom, R A is a divalent organic group having 1 to 10 carbon atoms, R B It is a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms.

[0128]

[0129] (In the formula, R4 is a hydrogen atom, or a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms, and the hydrogen atoms on the benzene ring in the formula may be substituted with a methyl group or a methoxy group.)

[0130] [(A) Polymer (resin)]

[0131] If the (A) polymer is a resin containing a structural unit represented by the general formula (1), the structure containing a high carbon density fluorene skeleton is repeatedly bonded by methylene groups, so that the separation and rebonding of carbon bonds are easily promoted by plasma irradiation, and a resist underlayer film having a diamond-like carbon structure can be formed. In addition, by containing a cross-linking group structure containing oxygen atoms and methylene groups, the curability, density, and heat resistance of the resist underlayer film are improved, and the scattering of solid components in the film caused by plasma irradiation can be alleviated, so that a resist underlayer film with a high degree of film thickness uniformity and dry etching resistance can be formed.

[0132] In the above general formula (1B), R A Examples of the divalent organic group having 1 to 10 carbon atoms include alkane diyl groups such as methylene, ethanediyl, propanediyl, butanediyl, pentanediyl, hexanediyl, octanediyl, and decanediyl; and aromatic diyl groups such as benzene diyl, methylbenzene diyl, and naphthalene diyl.

[0133] In the above general formula (1B), R B Examples of the monovalent organic group having 1 to 10 carbon atoms include alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-octyl, and n-decyl; and aryl groups such as phenyl, tolyl, xylyl, mesityl, and naphthyl.

[0134] A part or all of the hydrogen atoms possessed by the above-mentioned alkanediyl, arenediyl, alkyl, aryl, etc. may be optionally substituted, and examples of the substituent include alkoxy groups such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, n-pentoxy, and n-hexoxy; and alkoxycarbonyl groups such as methoxycarbonyl, ethoxycarbonyl, n-propoxycarbonyl, isopropoxycarbonyl, n-butoxycarbonyl, isobutoxycarbonyl, sec-butoxycarbonyl, tert-butoxycarbonyl, n-pentoxycarbonyl, and n-hexoxycarbonyl.

[0135] As a particularly preferred example, the structure shown in the following formula (1D) can be cited. When having such a structure, a resist lower layer film material having good thermal fluidity and excellent filling / planarization characteristics can be provided. In addition, heat resistance and film forming properties become good, the generation of sublimates during heat curing can be suppressed, the device contamination caused by the sublimates can be suppressed, and the generation of coating defects can be suppressed.

[0136]

[0137] (In the above formula, * represents a bonding site to an oxygen atom.)

[0138] In the above formula (1), Y is preferably any one of the structures represented by the following formula (Y-1). In the following structure, the position of the bond to the methylene group in formula (1) is not particularly limited.

[0139]

[0140]

[0141] (The hydrogen atoms in the above structure may be substituted with a hydroxyl group or a monovalent organic group having 1 to 10 carbon atoms.)

[0142] By using a polymer having the above structure, the carbon density in the resist underlayer film increases, so that separation and re-bonding of carbon bonds are easily promoted by plasma irradiation, and a resist underlayer film having a diamond-like carbon structure can be formed.

[0143] The hydrogen atoms in the above structure may be optionally substituted by a hydroxyl group or a monovalent organic group having 1 to 10 carbon atoms. Examples of the monovalent organic group having 1 to 10 carbon atoms include a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms or a group represented by the following general formula (Y-2).

[0144]

[0145] (wherein, * represents the bonding site to the structure of the above formula (Y-1), R A is a divalent organic group having 1 to 10 carbon atoms, R B is a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms, and s is 0 or 1. )

[0146] From the viewpoint of dry etching resistance, it is more preferable that the hydrogen atoms in the structure represented by the above formula (Y-1) are unsubstituted.

[0147] More preferable examples of the structure represented by the above formula (Y-1) include the following structures.

[0148]

[0149] In the above formula (1C), R4 is preferably a hydrogen atom, or a hydrocarbon group having 1 to 10 carbon atoms including a vinyl group or an ethynyl group, and the hydrogen atom on the benzene ring is preferably unsubstituted.

[0150] If R4 is a hydrogen atom, the curability of the polymer can be further improved, and the uniformity of the film thickness after plasma irradiation can be further improved. If R4 is a hydrocarbon group having 1 to 10 carbon atoms including a vinyl group or an acetylene group, the fluidity of the polymer can be further improved, and the flattening characteristics after plasma irradiation can be further improved.

[0151] Preferably, in the above formula (1), Ar1 and Ar2 are unsubstituted benzene rings or unsubstituted naphthalene rings, n2 is 1, and n3 is 0.

[0152] In addition, it is more preferred that: in the above formula (1), Ar1 and Ar2 are unsubstituted benzene rings, and in the above formula (1A), n1 is 0, n2 is 1 or 2, and n3 is 0.

[0153] According to a resist underlayer film forming method using a resist underlayer film-forming composition containing such a polymer, separation and re-bonding of carbon bonds are easily promoted by plasma irradiation, and a resist underlayer film having a diamond-like carbon structure can be formed.

[0154] In addition, by including a crosslinking group structure containing oxygen atoms, the curability, compactness, and heat resistance of the resist underlayer film are improved, and a resist underlayer film having excellent uniformity of film thickness before and after plasma irradiation can be formed. On the other hand, when there are fewer crosslinking group structures containing oxygen atoms, the number of oxygen atoms remaining in the film decreases, and therefore, it is preferred from the viewpoint of etching resistance. Therefore, n2 is more preferably 1, and n3 is more preferably 0.

[0155] In the above formula (1A), k is preferably 0.

[0156] According to such a resist underlayer film forming method, a polymer having excellent solvent solubility is formed, so that the storage stability of the resist underlayer film forming composition is improved, and a resist underlayer film forming method having excellent practicality can be provided.

[0157] Specifically, the following structure (1-A1) can be exemplified as an example of a preferred structure, but the present invention is not limited to these.

[0158]

[0159] (In the above formula, R2 is the same as in the above formula (1A).)

[0160] In the above formula (1A), n1 is more preferably 0.

[0161] In a resist underlayer film forming method using a resist underlayer film forming composition containing such a polymer, a structure containing a fluorene skeleton with a high carbon density is repeatedly bonded via methylene groups, so that separation and rebonding of carbon bonds are easily promoted by plasma irradiation, and a resist underlayer film having a diamond-like carbon structure can be formed. In addition, since a polymer having excellent fluidity is formed, a resist underlayer film forming method having excellent planarization characteristics can be provided.

[0162] In the above formula (1A), from the viewpoint of curability, R2 is more preferably a hydrogen atom or a structure represented by the general formula (1B).

[0163] By including the crosslinking group structure, the curability and heat resistance of the resist underlayer film are improved, and a resist underlayer film having excellent film thickness uniformity before and after plasma irradiation can be formed.

[0164] The following polymer is preferably used: in the above formula (1A), R2 is a hydrogen atom or a structure represented by the general formula (1B), and in the structure constituting the above R2, when the proportion of hydrogen atoms is set to a and the proportion of the structure represented by the above general formula (1B) is set to b, the relationship of a+b=1 and 0.1≤b≤0.9 is satisfied.

[0165] By controlling the ratio of hydrogen atoms to the above-mentioned general formula (1B) to the above-mentioned range, it is possible to highly exert fluidity and substrate adhesion, and a resist lower film material with increased embedding / planarization characteristics can be provided. If the range of b is ≤0.9, the content of hydroxyl groups is sufficient, and the adhesion with the substrate becomes good. In addition, in order to form a dense film, it is preferably a cross-linking reaction of hydroxyl groups, and from the viewpoint of heat resistance, it is also preferred to contain hydroxyl groups above a specified ratio. On the other hand, if the range of b is 0.1≤, the thermal fluidity of the resin becomes sufficient, and the embedding / planarization characteristics become good.

[0166] In the above formula (1A), R2 is more preferably a hydrogen atom.

[0167] In a resist underlayer film forming method using a resist underlayer film forming composition containing such a polymer, separation and recombination of carbon bonds can be easily promoted by plasma irradiation, and a resist underlayer film having a diamond-like carbon structure can be formed. In addition, the curability, compactness, and heat resistance of the resist underlayer film are improved, so that the film thickness change before and after plasma irradiation is small, and a resist underlayer film having excellent film thickness uniformity after plasma irradiation can be formed.

[0168] The weight average molecular weight of the polymer (A) is 2,500 to 20,000, preferably 5,000 to 18,000, and more preferably 7,000 to 15,000, based on gel permeation chromatography. When it is above 2,500, the amount of sublimation can be suppressed, and the degradation of the uniformity of the film thickness can be suppressed. When it is below 20,000, the solvent solubility of the resin can be maintained and precipitation over time can be prevented, so it is preferred from the perspective of storage stability. In addition, due to the excellent fluidity, excellent filling properties and excellent flatness can be achieved. In addition, it is possible to suppress outgassing during baking without damaging the solubility of the polymer in organic solvents.

[0169] Regarding the dispersion degree (Mw / Mn) of the aforementioned (A) polymer, it is preferably used in the range of 1.2 to 12. When the molecular weight distribution is narrowed by removing monomer components, oligomer components or low molecular weight bodies with a molecular weight (Mw) of 1,100 or less, the crosslinking efficiency becomes high. In addition, by suppressing the volatile components during baking and plasma irradiation, it is possible to form a resist underlayer film with excellent film thickness uniformity. By suppressing the volatile components during baking, it is also possible to prevent contamination around the baking cup. It should be noted that Mn represents the number average molecular weight.

[0170] The polymer (A) may be copolymerized with other copolymerizable monomers (A-2) as long as it contains the structural unit of the above formula (1). Specifically, phenol, o-cresol, m-cresol, p-cresol, 2,3-dimethylphenol, 2,5-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2,4-dimethylphenol, 2,6-dimethylphenol, 2,3,5-trimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2,4-dimethylphenol, 2,6-dimethylphenol, 2,3,5-trimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2,3,5-trimethylphenol, 2,3 ,4,5-trimethylphenol, 2-tert-butylphenol, 3-tert-butylphenol, 4-tert-butylphenol, 2-phenylphenol, 3-phenylphenol, 4-phenylphenol, 3,5-diphenylphenol, 2-naphthylphenol, 3-naphthylphenol, 4-naphthylphenol, 4-tritylphenol, resorcinol, 2-methylresorcinol, 4-methylresorcinol, 5-methylresorcinol, catechol, 4-tert-butylcatechol, 2- Methoxyphenol, 3-methoxyphenol, 2-propylphenol, 3-propylphenol, 4-propylphenol, 2-isopropylphenol, 3-isopropylphenol, 4-isopropylphenol, 2-methoxy-5-methylphenol, 2-tert-butyl-5-methylphenol, pyrogallol, thymol, isothymol, 1-naphthol, 2-naphthol, 2-methyl-1-naphthol, 4-methoxy-1-naphthol, 7-methoxy-2-naphthol and 1,5 -dihydroxynaphthalene, 1,7-dihydroxynaphthalene, 2,6-dihydroxynaphthalene and other dihydroxynaphthalene; 3-hydroxy-naphthalene-2-carboxylic acid methyl ester, indene, hydroxyindene, benzofuran, hydroxyanthracene, acenaphthylene, biphenyl, bisphenol, terphenol, dicyclopentadiene, tetrahydroindene, 4-vinylcyclohexene, norbornadiene, 5-vinylnorbornane-2-ene, α-pinene, β-pinene, limonene, etc., which can be copolymers of three or more species to which these substances are added.

[0171] When the above-mentioned (A) polymer contains structural units derived from other monomers (A-2), when the structural unit of the above-mentioned formula (1) is set to c, and the structural unit derived from other monomers (A-2) is set to d, the ratio of the structural unit of the above-mentioned formula (1) to the structural unit derived from other monomers (A-2) preferably satisfies the relationship of c+d=1, 0.5≤c≤0.9, and 0.1≤d≤0.5.

[0172] By including structural units derived from other monomers (A-2), the coating properties, film thickness uniformity, filling characteristics, planarization characteristics and dry etching resistance of the resist underlayer film can be appropriately adjusted. In order to form a resist underlayer film with good dry etching resistance after plasma irradiation, a polymer containing a large number of structural units of the above formula (1) is preferred, and a polymer not containing structural units derived from other monomers (A-2) is more preferred.

[0173] The blending ratio of the (A) polymer in the resist underlayer film-forming composition is not particularly limited, and can be, for example, 1 to 50 parts by mass, preferably 1 to 20 parts by mass, and more preferably 1 to 10 parts by mass, relative to 100 parts by mass of the total composition.

[0174] The aforementioned (A) polymer only needs to contain a resin having a structural unit of the above formula (1), and may further be blended with other compounds or polymers. The blending compound or the blending polymer is mixed with the resin having a structural unit shown in the general formula (1), which has the effect of improving the film-forming property of spin coating and the embedding property in the substrate with a height difference. In addition, the blending compound or the blending polymer is preferably a compound having a phenolic hydroxyl group.

[0175] Examples of such materials include phenol, o-cresol, m-cresol, p-cresol, 2,3-dimethylphenol, 2,5-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2,4-dimethylphenol, 2,6-dimethylphenol, 2,3,5-trimethylphenol, 3,4,5-trimethylphenol, 2-tert-butylphenol, 3-tert-butylphenol, 4-tert-butylphenol, 2-phenylphenol, 3-phenylphenol, 4-phenylphenol, 3,5-diphenylphenol, 2-naphthylphenol, 3-naphthylphenol, 4-naphthylphenol, 4-tritylphenol, resorcinol, 2-methylresorcinol, 4-methylresorcinol, 5-methylresorcinol, catechol, 4-tert-butylcatechol, 2-methoxybenzene, Phenol, 3-methoxyphenol, 2-propylphenol, 3-propylphenol, 4-propylphenol, 2-isopropylphenol, 3-isopropylphenol, 4-isopropylphenol, 2-methoxy-5-methylphenol, 2-tert-butyl-5-methylphenol, pyrogallol, thymol, isothymol, 4,4'-(9H-fluorene-9-ylidene)bisphenol, 2,2'-dimethyl-4 ,4'-(9H-fluorene-9-ylidene)bisphenol, 2,2'-diallyl-4,4'-(9H-fluorene-9-ylidene)bisphenol, 2,2'-difluoro-4,4'-(9H-fluorene-9-ylidene)bisphenol, 2,2'-diphenyl-4,4'-(9H-fluorene-9-ylidene)bisphenol, 2,2'-dimethoxy-4,4'-(9H-fluorene-9 - bisphenol, 2,3,2',3'-tetrahydro-(1,1')-spirobiindene-6,6'-diol, 3,3,3',3'-tetramethyl-2,3,2',3'-tetrahydro-(1,1')-spirobiindene-6,6'-diol, 3,3,3',3',4,4'-hexamethyl-2,3,2',3'-tetrahydro-(1,1')- Spirobiindene-6,6'-diol, 2,3,2',3'-tetrahydro-(1,1')-spirobiindene-5,5'-diol, 5,5'-dimethyl-3,3,3',3'-tetramethyl-2,3,2',3'-tetrahydro-(1,1')-spirobiindene-6,6'-diol, 1-naphthol, 2-naphthol, 2-methyl-1-naphthol, 4-methoxy -1-naphthol, 7-methoxy-2-naphthol and dihydroxynaphthalenes such as 1,5-dihydroxynaphthalene, 1,7-dihydroxynaphthalene and 2,6-dihydroxynaphthalene; 3-hydroxynaphthalene-2-carboxylic acid methyl ester, indene, hydroxyindene, benzofuran, hydroxyanthracene, acenaphthylene, biphenyl, bisphenol, terphenol, dicyclopentadiene, tetrahydroindene, 4-vinylcyclohexene, norbornadiene, 5-vinylnorborn-2-ene, α-pinene, β-pinene, limonene and other phenolic varnish resins; polyhydroxystyrene, polystyrene, polyvinylnaphthalene, polyvinylanthracene, polyvinylcarbazole, polyindene, polyacenaphthylene, polynorbornene, polycyclodecene, polytetracyclododecene, polynortricyclene, poly(meth)acrylate and copolymers thereof.In addition, naphthol dicyclopentadiene copolymers described in Japanese Patent Application Laid-Open No. 2004-205685, fluorene bisphenol novolac resins described in Japanese Patent Application Laid-Open No. 2005-128509, acenaphthylene copolymers described in Japanese Patent Application Laid-Open No. 2005-250434, fullerenes having a phenol group described in Japanese Patent Application Laid-Open No. 2006-227391, bisphenol compounds and novolac resins thereof described in Japanese Patent Application Laid-Open No. 2006-293298, novolac resins of adamantane phenol compounds described in Japanese Patent Application Laid-Open No. 2006-285095, bisnaphthol compounds and novolac resins thereof described in Japanese Patent Application Laid-Open No. 2010-122656, fullerene resin compounds described in Japanese Patent Application Laid-Open No. 2008-158002, etc. may be blended.

[0176] The amount of the compound or polymer for blending is preferably 5 to 100 parts by mass, more preferably 5 to 50 parts by mass, based on 100 parts by mass of the (A) polymer (resin having a structural unit represented by the general formula (1)).

[0177] In order to form a resist underlayer film having excellent dry etching resistance after plasma irradiation, the compound or polymer for blending is preferably contained in a small amount, and more preferably contains no compound or polymer for blending.

[0178] [(B) Organic solvent]

[0179] The organic solvent that can be used in the resist underlayer film-forming composition is not particularly limited as long as it can dissolve the polymer (A), but is preferably an organic solvent that can also dissolve the crosslinking agent, surfactant, acid generator, and plasticizer described below.

[0180] Specifically, for example, the solvents described in paragraphs

[0091] to

[0092] of Japanese Patent Application Laid-Open No. 2007-199653 may 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 is preferably used.

[0181] The amount of the organic solvent added is preferably adjusted according to the desired film thickness of the resist underlayer film, and is usually in the range of 100 to 50,000 parts by mass based on 100 parts by mass of the (A) polymer.

[0182] [(B-1) High boiling point solvent]

[0183] In addition, in the above-mentioned resist underlayer film forming composition, (B) the organic solvent can be used in the form of a mixture of one or more organic solvents having a boiling point lower than 180 degrees and one or more organic solvents having a boiling point higher than 180 degrees (hereinafter referred to as "(B-1) high boiling point solvent").

[0184] Specific examples of the organic solvent having a boiling point of less than 180 degrees include propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, 2-heptanone, cyclopentanone, and cyclohexanone.

[0185] The high boiling point solvent (B-1) is not particularly limited to hydrocarbons, alcohols, ketones, esters, ethers, chlorine-based solvents, and the like as long as it can dissolve the components of the resist underlayer film forming composition used in the present invention. Specific examples thereof include 1-octanol, 2-ethylhexanol, 1-nonanol, 1-decanol, 1-undecanol, ethylene glycol, 1,2-propylene glycol, 1,3-butanediol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol, 2-ethyl- 1,3-Hexanediol, Diethylene Glycol, Dipropylene Glycol, Triethylene Glycol, Tripropylene Glycol, Glycerol, Nonyl Acetate, Monohexyl Ether, Ethylene Glycol Mono-2-ethylhexyl Ether, Ethylene Glycol Monophenyl Ether, Ethylene Glycol Monobenzyl Ether, Diethylene Glycol Monoethyl Ether, Diethylene Glycol Monoisopropyl Ether, Diethylene Glycol Mono-n-butyl Ether, Diethylene Glycol Monoisobutyl Ether, Diethylene Glycol Monohexyl Ether, Diethylene Glycol Monophenyl Ether, Diethylene Glycol Monobenzyl Ether, Diethylene Glycol Diethyl Ether, Diethylene Glycol Dibutyl Ether, Diethylene Glycol Butyl Methyl Ether, Triethylene Glycol Dimethyl Ether, triethylene glycol monomethyl ether, triethylene glycol n-butyl ether, triethylene glycol butyl methyl ether, tetraethylene glycol dimethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-n-butyl ether, tripropylene glycol dimethyl ether, tripropylene glycol monomethyl ether, tripropylene glycol mono-n-propyl ether, tripropylene glycol mono-n-butyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, triacetin, propylene glycol di Acetate, dipropylene glycol methyl n-propyl ether, dipropylene glycol methyl ether acetate, 1,4-butanediol diacetate, 1,3-butanediol diacetate, 1,6-hexanediol diacetate, triethylene glycol diacetate, γ-butyrolactone, methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, dihexyl malonate, diethyl succinate, dipropyl succinate, dibutyl succinate, dihexyl succinate, dimethyl adipate, diethyl adipate and dibutyl adipate, etc., which can be used alone or in combination.

[0186] (B-1) The high boiling point solvent can be appropriately selected from, for example, the above-mentioned solvents according to the temperature at which the above-mentioned resist underlayer film-forming composition is heat-treated. The boiling point of the high boiling point solvent (B-1) is preferably 180°C to 300°C, and more preferably 200°C to 300°C. If it is such a boiling point, there is no need to worry about volatilization too fast during baking (heat treatment) due to the boiling point being too low, so that sufficient thermal fluidity can be obtained during film formation. In addition, if it is such a boiling point, there is no situation where the boiling point is too high and does not volatilize after baking and remains in the film, so there is no need to worry about adverse effects on film properties such as etching resistance.

[0187] In addition, the blending amount of the high boiling point solvent (B-1) is preferably 1 to 200 parts by mass, more preferably 1 to 100 parts by mass, relative to 100 parts by mass of the polymer (A). If such a blending amount is used, there is no need to worry that the blending amount is too small and sufficient thermal fluidity cannot be imparted during baking, or that the blending amount is too large and remains in the film, resulting in deterioration of film properties such as etching resistance, which is preferred.

[0188] [(C) Cross-linking agent]

[0189] Furthermore, a crosslinking agent (C) may be added to the resist underlayer film-forming composition in order to improve curability and dry etching resistance.

[0190] Specifically, as the cross-linking agent (C), a compound having a structure represented by the following general formula (C-1) is particularly preferred.

[0191]

[0192] (In the above general formula (C-1), W1 and W2 are each a benzene ring or a naphthalene ring which may have a substituent, R2 represents a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, and X is any one of the groups represented by the following general formula (2).)

[0193]

[0194] (Wherein, * indicates the bonding site.)

[0195] By including the crosslinking agent (C), the crosslinking density and hardness of the resist underlayer film can be further increased without deteriorating the dry etching resistance of the resist underlayer film-forming composition.

[0196] The ratio Mw / Mn of the polystyrene-equivalent weight average molecular weight Mw and the number average molecular weight Mn of the cross-linking agent (C) is preferably 1.00≤Mw / Mn≤1.25.

[0197] If the molecular weight dispersion of the cross-linking agent is as described above, the thermal fluidity of the resist underlayer film forming composition becomes good. Therefore, when it is mixed with the resist underlayer film material, it can not only well fill the fine structure formed on the substrate but also form a resist underlayer film with a flat substrate as a whole.

[0198] As other (C) crosslinking agents, there are no particular limitations, and various well-known crosslinking agents can be widely used. As one example, 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, epoxy crosslinking agents, phenol crosslinking agents (e.g., hydroxymethyl or alkoxymethyl type crosslinking agents of polynuclear phenols) can be illustrated.

[0199] As melamine-based crosslinking agents, specifically, hexamethoxymethylated melamine, hexabutoxymethylated melamine, their alkoxy and / or hydroxyl substitutions, and their partial self-condensation products can be exemplified. As glycoluril-based crosslinking agents, specifically, tetramethoxymethylated glycoluril, tetrabutoxymethylated glycoluril, their alkoxy and / or hydroxyl substitutions, and their partial self-condensation products can be exemplified. As benzoguanamine-based crosslinking agents, specifically, tetramethoxymethylated benzoguanamine, tetrabutoxymethylated benzoguanamine, their alkoxy and / or hydroxyl substitutions, and their partial self-condensation products can be exemplified. As urea-based crosslinking agents, specifically, dimethoxymethylated dimethoxyethylene urea, its alkoxy and / or hydroxyl substitutions, and their partial self-condensation products can be exemplified. As β-hydroxyalkylamide-based crosslinking agents, specifically, N,N,N',N'-tetrakis(2-hydroxyethyl)adipamide can be exemplified. Specific examples of isocyanurate crosslinking agents include triglycidyl isocyanurate and triallyl isocyanurate. Specific examples of aziridine crosslinking agents include 4,4'-bis(ethyleneiminocarbonylamino)diphenylmethane and 2,2-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate]. Specific examples of the oxazoline crosslinking agent include 2,2'-isopropylidenebis(4-benzyl-2-oxazoline), 2,2'-isopropylidenebis(4-phenyl-2-oxazoline), 2,2'-methylenebis-4,5-diphenyl-2-oxazoline, 2,2'-methylenebis-4-phenyl-2-oxazoline, 2,2'-methylenebis-4-tert-butyl-2-oxazoline, 2,2'-bis(2-oxazoline), 1,3-phenylenebis(2-oxazoline), 1,4-phenylenebis(2-oxazoline), and 2-isopropenyloxazoline copolymers. Specific examples of the epoxy crosslinking agent include diglycidyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,4-cyclohexanedimethanol diglycidyl ether, poly(glycidyl methacrylate), trimethylolethane triglycidyl ether, trimethylolpropane triglycidyl ether, and pentaerythritol tetraglycidyl ether.

[0200] Specific examples of the polynuclear phenol-based crosslinking agent include compounds represented by the following general formula (C-2).

[0201]

[0202] (In the formula, Q is a single bond or a q-valent hydrocarbon group having 1 to 20 carbon atoms. R3 is a hydrogen atom or a methyl group. q is an integer of 1 to 5.)

[0203] Q in the general formula (C-2) 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. When Q is a q-valent hydrocarbon group having 1 to 20 carbon atoms, Q is a q-valent hydrocarbon group obtained by removing q hydrogen atoms from a hydrocarbon having 1 to 20 carbon atoms. More specifically, examples of the hydrocarbon having 1 to 20 carbon atoms include methane, ethane, propane, butane, isobutane, pentane, cyclopentane, hexane, cyclohexane, methylpentane, methylcyclohexane, dimethylcyclohexane, trimethylcyclohexane, benzene, toluene, xylene, ethylbenzene, ethylisopropylbenzene, diisopropylbenzene, methylnaphthalene, ethylnaphthalene, and eicosane.

[0204] R3 in the above general formula (C-2) is a hydrogen atom or a methyl group, and is preferably a methyl group.

[0205] By including the compound represented by the general formula (C-2) as the cross-linking agent (C), the density of the film can be improved, thereby further improving the heat resistance of the resist underlayer film-forming composition.

[0206] As examples of compounds represented by the above general formula (C-2), specifically, the following compounds can be illustrated, but are not limited to them. In the following formula, R3 is the same as above. When q=3 is satisfied and R3 is a methyl group, it is preferred from the viewpoint of improving curability, uniformity of film thickness and reducing sublimation products, and particularly preferred are trisphenolmethane, trisphenolethane, 1,1,1-tris(4-hydroxyphenyl)ethane, and hexamethoxymethylated bodies of tris(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene.

[0207]

[0208]

[0209] The above-mentioned (C) cross-linking agent can be used alone or in combination of two or more. The content of the (C) cross-linking agent is preferably 5 to 100 parts by mass, more preferably 10 to 50 parts by mass, relative to 100 parts by mass of the above-mentioned (A) polymer. If the addition amount is 5 parts by mass or more, the cross-linking reaction with the (A) polymer is promoted to form a dense film with excellent curing properties, thereby forming a resist lower layer film with good heat resistance, dry etching resistance and film thickness uniformity. On the other hand, if the addition amount is less than 100 parts by mass, the generation of passivated sublimates accompanying the cross-linking reaction of the (A) polymer and the (C) cross-linking agent can be suppressed, and the generation of sublimates and the degradation of film thickness uniformity can be reduced.

[0210] [(D) Surfactant]

[0211] In order to improve the coating property in spin coating, a surfactant (D) may be added to the resist underlayer film-forming composition. As the surfactant, for example, the surfactants described in

[0142] to

[0147] in Japanese Patent Application Publication No. 2009-269953 may be used. The amount of the surfactant added is preferably 0.001 to 20 parts by mass, more preferably 0.01 to 10 parts by mass, relative to 100 parts by mass of the polymer (A).

[0212] [(E) Acid generator]

[0213] The resist underlayer film-forming composition may be a composition that generates an acid by thermal decomposition or a composition that generates an acid by light irradiation, and any of these may be added. Specifically, the materials described in paragraphs

[0061] to

[0085] of Japanese Patent Application Laid-Open No. 2007-199653 may be added, but are not limited thereto.

[0214] The acid generator may be used alone or in combination of two or more. The amount of the acid generator added is preferably 0.05 to 50 parts by mass, more preferably 0.1 to 10 parts by mass, based on 100 parts by mass of the (A) polymer.

[0215] [(F) Plasticizer]

[0216] In addition, in order to further improve the thermal fluidity, a plasticizer (F) may be added to the resist underlayer film-forming composition. The plasticizer is not particularly limited, and plasticizers of various known systems can be widely used. As an example, low molecular weight compounds such as phthalates, adipic acid esters, phosphates, trimellitic acid esters, and citrates; polymers such as polyethers, polyesters, and polyacetal polymers described in Japanese Patent Application Laid-Open No. 2013-253227 can be illustrated. The amount of the plasticizer added is preferably 5 to 500 parts by mass, and more preferably 10 to 200 parts by mass, relative to 100 parts by mass of the polymer (A).

[0217] In addition, in addition to the above-mentioned additives, an additive (fluidity promoter) for further improving thermal fluidity can be added to the above-mentioned resist underlayer film forming composition. The above-mentioned additive is not particularly limited as long as it helps to improve thermal fluidity, impart fill characteristics and planarization characteristics. For example, it is preferred to use a liquid additive having a polyethylene glycol or polypropylene glycol structure; or a thermally decomposable polymer having a weight reduction rate of 40% by mass or more between 30°C and 250°C and a weight average molecular weight of 300 to 200,000. The thermally decomposable polymer preferably contains a repeating unit having an acetal structure represented by the following general formula (DP1) or (DP1a).

[0218]

[0219] (In the formula, R6 is a hydrogen atom or an optionally substituted saturated or unsaturated monovalent organic group having 1 to 30 carbon atoms. Y is a saturated or unsaturated divalent organic group having 2 to 30 carbon atoms.)

[0220]

[0221] (Where R 6a Y is an alkyl group having 1 to 4 carbon atoms. a It is a saturated or unsaturated divalent hydrocarbon group having 4 to 10 carbon atoms, and optionally has an ether bond. n represents the average number of repeating units, and is 3 to 500.

[0222] <Pattern Formation Method>

[0223] In addition, in the present invention, as a pattern forming method using the above-mentioned resist underlayer film forming composition and based on a two-layer resist process, the following pattern forming method is provided, which is characterized in that a resist underlayer film is formed on a processed substrate by the resist underlayer film forming method of the present invention, a resist upper layer film is formed on the resist underlayer film using a photoresist material, the resist upper layer film is subjected to pattern exposure, and then developed using a developer to form a pattern on the resist upper layer film, using the resist upper layer film with the pattern as a mask, the pattern is transferred to the resist underlayer film by dry etching, the processed substrate is processed using the resist underlayer film with the pattern as a mask, and a pattern is formed on the processed substrate.

[0224] The resist upper film in the two-layer resist process is preferably a photosensitive organic metal oxide film. The photosensitive organic metal oxide film shows resistance to etching based on oxygen-based gas, so in the two-layer resist process, it is preferred to use an etching gas mainly composed of oxygen-based gas to perform dry etching of the resist lower film using the resist upper film as a mask.

[0225] In addition, the present invention provides a method for forming a pattern on a substrate to be processed, as a method for forming a pattern based on a three-layer resist process using the resist underlayer film-forming composition, wherein the method comprises the following steps:

[0226] (I-1) a step of forming a resist underlayer film on a substrate to be processed by the resist underlayer film forming method of the present invention;

[0227] (I-2) a step of forming a resist intermediate film on the resist underlayer film;

[0228] (I-3) a step of forming a resist upper layer film on the resist intermediate film using a photoresist material;

[0229] (I-4) a step of exposing the resist upper layer film to pattern exposure and then developing the resist upper layer film with a developer to form a pattern on the resist upper layer film;

[0230] (I-5) a step of transferring the pattern to the resist intermediate film by dry etching using the resist upper layer film having the pattern as a mask;

[0231] (I-6) a step of transferring the pattern to the resist underlayer film by dry etching using the resist intermediate film to which the pattern is transferred as a mask; and

[0232] (I-7) A step of processing the substrate to be processed using the resist underlayer film having the pattern formed thereon as a mask to form a pattern on the substrate to be processed.

[0233] use Figure 1 , an example of a pattern forming method based on a three-layer resist process is described. First, Figure 1 As in (A), by the resist underlayer film forming method of the present invention, a resist underlayer film 3 is formed on the processed layer 2 of a processed substrate 1A including a supporting substrate 1 and a processed layer 2 formed thereon, a resist intermediate film 4 (for example, a silicon-containing resist intermediate film) is formed on the resist underlayer film 3 using a resist intermediate film material, and a resist upper film 5 is formed on the resist intermediate film 4 using a photoresist material. Next, as Figure 1 As in (B), by pattern exposure, an exposed portion 6 is formed in the resist upper film 5. Next, the exposed portion 6 is developed using a developer, such as Figure 1 As in (C), the resist upper film 5 is formed into a resist upper film pattern 5a. Next, the resist upper film 5 having the pattern 5a is used as a mask, and dry etching is performed. Figure 1 As in (D), the resist intermediate film pattern 4a is transferred to the resist intermediate film 4. Next, the resist intermediate film 4 to which the pattern 4a is transferred is used as a mask, and dry etching is performed. Figure 1 As in (E), the resist underlayer film pattern 3a is transferred to the resist underlayer film 3. Then, the resist underlayer film 3 having the pattern 3a is used as a mask to process the processed layer 2 of the processed substrate 1A, as shown in FIG. Figure 1 As in (F), a pattern 2a is formed on the aforementioned processed substrate 1.

[0234] The silicon-containing resist intermediate film of the above-mentioned three-layer resist process shows resistance to etching based on oxygen-based gases. Therefore, in the above-mentioned three-layer resist process, it is preferred to use an etching gas with oxygen-based gas as the main body to perform dry etching of the resist lower layer film using the silicon-containing resist intermediate film as a mask.

[0235] As the silicon-containing resist intermediate film of the above-mentioned three-layer resist process, it is also preferred to use an intermediate film based on polysiloxane. By providing the silicon-containing resist intermediate film with an anti-reflection effect, reflection can be suppressed. In particular, for 193nm exposure purposes, if a material containing a large number of aromatic groups and having a high etching selectivity with the substrate is used as an organic film, the k value becomes higher and the substrate reflection becomes higher, but as a silicon-containing resist intermediate film, by having an absorption that exhibits an appropriate k value, reflection can be suppressed, and the substrate reflection can be set to less than 0.5%. As a silicon-containing resist intermediate film with an anti-reflection effect, in 248nm or 157nm exposure purposes, it is preferred to use a polysiloxane with pendant anthracene and cross-linked by acid or heat, and in 193nm exposure purposes, it is preferred to use a polysiloxane with pendant phenyl or light-absorbing groups having silicon-silicon bonds and cross-linked by acid or heat.

[0236] Furthermore, the present invention provides a pattern forming method using the resist underlayer film forming composition and based on a four-layer resist process, which comprises the following steps: forming a resist underlayer film on a substrate to be processed by the resist underlayer film forming method of the present invention; forming a silicon-containing resist interlayer film on the resist underlayer film using a silicon-containing resist interlayer film material; forming an organic antireflection film (BARC) or a close-fitting film on the silicon-containing resist interlayer film; and forming a photoresist material on the BARC or close-fitting film. A resist upper film is formed on the film, and after the resist upper film is pattern-exposed, it is developed using a developer to form a pattern on the resist upper film, using the resist upper film with the pattern as a mask, and the pattern is transferred to the BARC or the sealing film and the silicon-containing resist intermediate film using dry etching, and the silicon-containing resist intermediate film with the pattern transferred is used as a mask, and the pattern is transferred to the resist lower film using dry etching, and the resist lower film with the pattern is used as a mask to process the processed substrate to form a pattern on the processed substrate.

[0237] In addition, an inorganic hard mask can be formed to replace the silicon-containing resist intermediate film. In this case, at least the resist underlayer film forming composition of the present invention is used to form a resist underlayer film on the workpiece, an inorganic hard mask selected from silicon oxide film, silicon nitride film, and silicon oxide nitride film is formed on the resist underlayer film, a photoresist composition is used to form a resist upper film on the inorganic hard mask, a circuit pattern is formed on the resist upper film, and the inorganic hard mask is etched using the resist upper film with the pattern as a mask. The resist underlayer film is etched using the inorganic hard mask with the pattern as a mask, and further, the workpiece is etched using the resist underlayer film with the pattern as a mask to form a pattern on the workpiece, thereby forming a circuit pattern of a semiconductor device on the substrate.

[0238] As described above, when an inorganic hard mask is formed on the resist underlayer film, a silicon oxide film, a silicon nitride film, and a silicon oxide nitride film (SiON film) can be formed by using a CVD method, an ALD method, or the like. For example, a method for forming a silicon nitride film is described in Japanese Patent Application Publication No. 2002-334869 and International Publication No. 2004 / 066377. The film thickness of the inorganic hard mask is preferably 5 to 200 nm, more preferably 10 to 100 nm. In addition, as an inorganic hard mask, it is most preferable to use a SiON film that has a high effect as an anti-reflection film. In order to make the substrate temperature reach 300 to 500° C. when forming the SiON film, the resist underlayer film must withstand a temperature of 300 to 500° C. The resist underlayer film forming composition used in the present invention has high heat resistance and can withstand high temperatures of 300°C to 500°C. Therefore, it can be a combination of an inorganic hard mask formed by CVD or ALD and a resist underlayer film formed by spin coating.

[0239] As described above, a photoresist film as a resist upper film can be formed on an inorganic hard mask, and an organic anti-reflection film (BARC) or a close-fitting film can be formed on the inorganic hard mask by spin coating, and a photoresist film can be formed thereon. In particular, when a SiON film is used as an inorganic hard mask, the anti-reflection films of the SiON film and the BARC can suppress reflection even in liquid immersion exposure with a high NA exceeding 1.0. As another advantage of forming a BARC, there is an effect of reducing the tailing of the photoresist pattern directly above the SiON film.

[0240] In the above-mentioned pattern forming method, the resist upper layer film may be either positive or negative, and the same film as the commonly used photoresist composition may be used. In addition, the photoresist composition may contain metal atoms such as Sn, In, Ga, Ge, Al, Ce, La, Cs, Zr, Hf, Ti, Bi, Sb, and Zn. When the resist upper layer film is formed using the above-mentioned photoresist composition, it may be a spin coating method or a method of forming it by a vapor deposition process based on CVD or ALD.

[0241] When the photoresist composition is formed by spin coating, a pre-baking is performed after the resist is applied, preferably at 60 to 180° C. and for 10 to 300 seconds. Thereafter, exposure is performed according to a conventional method, and post-exposure baking (PEB) and development are performed to obtain a resist pattern. It should be noted that the thickness of the resist upper layer film is not particularly limited, but is preferably 10 to 500 nm, and particularly preferably 20 to 400 nm.

[0242] When the photoresist composition is formed by evaporation treatment based on CVD or ALD, the resist composition is a metal oxide film with EUV sensitivity, and the metal is selected from Sn, Zr, Hf, Ti, Bi, Sb, etc., wherein Sn with excellent EUV sensitivity is preferred. The film containing the metal oxide can be a photosensitive organic metal oxide film such as an organic tin oxide (such as a halogenated alkyl Sn, an alkoxyalkyl Sn, or an amide alkyl Sn). Several specific examples of suitable precursors include trimethyltin chloride, dimethyltin dichloride, methyltin trichloride, tris(dimethylamino)methyltin(IV), and (dimethylamino)trimethyltin(IV).

[0243] The metal oxide film can be deposited by PECVD or PEALD using, for example, a Lam Vector (registered trademark) tool. In the ALD embodiment, the Sn oxide precursor is separated from the O precursor / plasma. The evaporation temperature is preferably in the range of 50°C to 600°C. The evaporation pressure is preferably between 100 and 6000 mTorr. The flow rate of the precursor liquid of the film containing the metal oxide (for example, an organic tin oxide precursor) can be 0.01 to 10 cmm, and the gas flow rate (CO2, CO, Ar, N2) can be 100 to 10000 sccm. Regarding plasma power, high-frequency plasma (for example, 13.56 MHz, 27.1 MHz or a higher frequency) can be used, which is 200 to 1000 W relative to a 300 mm wafer station. The evaporation thickness is preferably

[0244] Examples of the exposure light include high-energy rays having a wavelength of 300 nm or less, and specifically, excimer lasers of 248 nm, 193 nm, and 157 nm, and soft X-rays, electron beams, and X-rays of 3 to 20 nm.

[0245] As a method for patterning the resist upper layer film, patterning is preferably performed by photolithography with a wavelength of 5 nm to 300 nm, direct writing with electron beams, nanoimprinting, or a combination thereof.

[0246] In addition, the development method in the above-mentioned pattern forming method is preferably set to alkali development or development with an organic solvent.

[0247] Then, etching is performed using the obtained resist pattern as a mask. The etching of the silicon-containing resist intermediate film and the inorganic hard mask in the three-layer resist process is performed using a freon-based gas and the upper layer resist pattern as a mask. Thus, a silicon-containing resist intermediate film pattern and an inorganic hard mask pattern are formed.

[0248] Next, the resist underlayer film is etched using the obtained silicon-containing resist intermediate film pattern and the inorganic hard mask pattern as masks. The resist underlayer film is preferably etched using an etching gas mainly containing an oxygen-based gas.

[0249] The subsequent etching of the workpiece can also be performed by conventional methods. For example, if the workpiece is SiO2, SiN, or a silicon dioxide-based low dielectric constant insulating film, the etching is performed mainly using a Freon-based gas. Regarding substrate processing, when etching is performed using a Freon-based gas, the silicon-containing resist intermediate film pattern in the three-layer resist process is stripped off while the substrate is being processed.

[0250] The resist underlayer film obtained by the resist underlayer film forming method of the present invention has a feature of being excellent in etching resistance when etching such a workpiece.

[0251] It should be noted that there is no particular limitation on the object to be processed (processed substrate), and substrates such as Si, α-Si, p-Si, SiO2, SiN, SiON, W, TiN, Al, etc. can be used; an object on which a processed layer is formed on the substrate (support substrate), etc. As the processed layer, various Low-k films such as Si, SiO2, SiON, SiN, p-Si, α-Si, W, W-Si, Al, Cu, Al-Si, etc. and barrier films thereof can be used, and a thickness of 50 to 10,000 nm can usually be formed, and a thickness of 100 to 5,000 nm can be formed in particular. It should be noted that when forming a film of the processed layer, the substrate and the processed layer can be made of different materials.

[0252] In addition, the present invention provides a pattern forming method, which is a method for forming a pattern on a processed substrate, comprising the following steps:

[0253] (II-1) a step of forming a resist underlayer film on a substrate to be processed having a height difference by the resist underlayer film forming method of the present invention;

[0254] (II-2) forming a resist upper layer film on the upper layer of the resist lower layer film;

[0255] (II-3) a step of exposing the resist upper layer film to pattern exposure and then developing the resist upper layer film with a developer to form a pattern on the resist upper layer film;

[0256] (II-4) a step of transferring the pattern to the resist lower film by dry etching using the resist upper film having the pattern formed thereon as a mask;

[0257] (II-5) A step of processing the substrate to be processed using the resist underlayer film having the pattern formed thereon as a mask to form a pattern on the substrate to be processed.

[0258] An organic underlayer film, a silicon-containing film, an inorganic hard mask, an organic antireflective film (BARC), an adhesion film, or the like may be stacked between the resist underlayer film and the upper resist layer.

[0259] Preferably, the process includes: filling a processed substrate having a height difference with a resist underlayer film, transferring a fine pattern formed on the upper layer of the resist underlayer film (for example, a pattern formed by multi-patterning techniques such as SADP and SAQP) to a hard mask directly above the resist underlayer film, transferring the hard mask pattern to the resist underlayer film, and transferring the resist underlayer film pattern to the processed substrate.

[0260] The materials, film thicknesses and formation methods of the organic underlayer film, silicon-containing film, inorganic hard mask, organic antireflection film (BARC), adhesion film and processed substrate are the same as those described above.

[0261] The resist underlayer film forming method of the present invention has excellent filling characteristics and planarization characteristics for a workpiece substrate having a height difference and excellent etching resistance when the workpiece substrate is etched, and is therefore effective in the above-mentioned pattern forming method.

[0262] Example

[0263] Hereinafter, synthesis examples, embodiments and comparative examples are shown to more specifically describe the present invention, but the present invention is not limited thereto. It should be noted that, as molecular weight and dispersity, the weight average molecular weight (Mw) and number average molecular weight (Mn) of polystyrene conversion based on gel permeation chromatography (GPC) using tetrahydrofuran as an eluent are obtained to obtain dispersity (Mw / Mn).

[0264] In the case of polymers (A1) to (A11) and comparative example compounds (R1) to (R5), the following compounds (G1) to (G10) were used.

[0265]

[0266] Synthesis Example (A) Synthesis of polymer

[0267] [Synthesis Example 1] Synthesis of polymer (A1)

[0268]

[0269] Under a nitrogen atmosphere, 100.0 g of compound (G1), 14.7 g of 92% formaldehyde, 5.0 g of p-toluenesulfonic acid and 200 g of ethylene glycol were added, and the mixture was stirred at an internal temperature of 140° C. for 8 hours. After cooling to room temperature, 500 g of methyl isobutyl ketone was added, and the organic layer was washed five times with 200 g of pure water, and then dried under reduced pressure. 300 g of THF was added to the residue, and the polymer was reprecipitated with 1200 g of hexane. The precipitated polymer was separated by filtration and dried under reduced pressure to obtain polymer (A1).

[0270] When the weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, the following results were obtained.

[0271] (A1): Mw=5,610, Mw / Mn=3.60

[0272] [Synthesis Example 2] Synthesis of polymer (A2)

[0273]

[0274] Under a nitrogen atmosphere, 180 g of compound (G2), 75 g of 37% formalin solution, and 5 g of oxalic acid were added, and the mixture was stirred at an internal temperature of 100° C. for 24 hours. After cooling to room temperature, 500 g of methyl isobutyl ketone was added, and the organic layer was washed 5 times with 200 g of pure water, and then the organic layer was dried under reduced pressure. 320 g of THF was added to the residue, and the polymer was reprecipitated with 1350 g of hexane. The precipitated polymer was separated by filtration and dried under reduced pressure to obtain polymer (A2).

[0275] When the weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, the following results were obtained.

[0276] (A2): Mw=11,200, Mw / Mn=4.35

[0277] [Synthesis Example 3] Synthesis of polymer (A3)

[0278]

[0279] Under a nitrogen atmosphere, 100.0 g of compound (G2), 48.3 g of compound (G3) and 450 g of 1,2-dichloroethane were mixed and uniformly dispersed at an internal temperature of 60°C. Then, 82.4 g of methanesulfonic acid was added dropwise over 1 hour, and the mixture was heated and stirred at an internal temperature of 70°C for 24 hours. After cooling to room temperature, 1000 g of methyl isobutyl ketone was added, and the organic layer was washed 5 times with 200 g of pure water, and then the organic layer was dried under reduced pressure. 450 g of THF was added to the residue, and 1800 g of hexane was used to reprecipitate the polymer. The precipitated polymer was separated by filtration and dried under reduced pressure to obtain polymer (A3).

[0280] When the weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, the following results were obtained.

[0281] (A3): Mw=9,800, Mw / Mn=3.50

[0282] [Synthesis Example 4] Synthesis of polymer (A4)

[0283]

[0284] Under a nitrogen atmosphere, 180.0 g of compound (G2), 58.0 g of compound (G4), 75.0 g of 37% formalin solution, 5.0 g of oxalic acid and 500 g of 2-methoxy-1-propanol were added, and the mixture was stirred at an internal temperature of 100° C. for 24 hours. After cooling to room temperature, 1000 g of methyl isobutyl ketone was added, and the organic layer was washed 5 times with 200 g of pure water, and then the organic layer was dried under reduced pressure. 480 g of THF was added to the residue, and the polymer was reprecipitated using 2400 g of hexane. The precipitated polymer was separated by filtration and dried under reduced pressure to obtain polymer (A4).

[0285] When the weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, the following results were obtained.

[0286] (A4): Mw=9,350, Mw / Mn=3.76

[0287] [Synthesis Example 5] Synthesis of polymer (A5)

[0288]

[0289] In a nitrogen atmosphere, 50.0 g of the compound (A2) obtained in Synthesis Example 2, 38.1 g of potassium carbonate, and 200 g of dimethylformamide were added, and after a uniform dispersion was prepared at 50° C., 23.4 g of allyl bromide was slowly added dropwise. The mixture was stirred at an internal temperature of 50° C. for 8 hours. After cooling to room temperature, 400 ml of methyl isobutyl ketone and 300 g of pure water were added to the reaction solution to dissolve the precipitated salt, and the separated water layer was removed. Furthermore, the organic layer was washed 6 times with 100 g of a 3% nitric acid aqueous solution and 100 g of pure water, and then the organic layer was dried under reduced pressure to obtain a polymer (A5).

[0290] When the weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, the following results were obtained.

[0291] (A5): Mw=12,200, Mw / Mn=4.38

[0292] [Synthesis Example 6] Synthesis of polymer (A6)

[0293]

[0294] In a nitrogen atmosphere, 50.0 g of the compound (A2) obtained in Synthesis Example 2, 41.9 g of potassium carbonate, and 200 g of dimethylformamide were added to prepare a uniform dispersion at 50° C., and then 29.5 g of 3-bromo-1-propyne was slowly added dropwise, and stirred at an internal temperature of 50° C. for 8 hours. After cooling to room temperature, 400 ml of methyl isobutyl ketone and 300 g of pure water were added to the reaction solution to dissolve the precipitated salt, and the separated water layer was removed. Furthermore, the organic layer was washed 6 times with 100 g of a 3% nitric acid aqueous solution and 100 g of pure water, and then the organic layer was dried under reduced pressure to obtain a polymer (A6).

[0295] When the weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, the following results were obtained.

[0296] (A6): Mw=12,800, Mw / Mn=4.43

[0297] [Synthesis Example 7] Synthesis of polymer (A7)

[0298]

[0299] Under a nitrogen atmosphere, 100.0 g of compound (G5), 24.3 g of a 37% formalin solution, and 300 g of 2-methoxy-1-propanol were added to form a uniform solution at an internal temperature of 80°C, and then 25.0 g of a 20% p-toluenesulfonic acid 2-methoxy-1-propanol solution was slowly added, and the mixture was stirred at an internal temperature of 110°C for 8 hours. After cooling to room temperature, 500 g of methyl isobutyl ketone was added, and the organic layer was washed 5 times with 200 g of pure water, and then the organic layer was dried under reduced pressure. 300 g of THF was added to the residue, and 1500 g of methanol was used to reprecipitate the polymer. The precipitated polymer was separated by filtration and dried under reduced pressure to obtain a polymer (A7).

[0300] When the weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, the following results were obtained.

[0301] (A7): Mw=5,340, Mw / Mn=2.40

[0302] [Synthesis Example 8] Synthesis of polymer (A8)

[0303]

[0304] Under a nitrogen atmosphere, 90.1 g of compound (G6), 25.2 g of a 37% formalin solution, and 270 g of 2-methoxy-1-propanol were added, and a uniform solution was prepared at an internal temperature of 80°C. Then, 18 g of a 20% p-toluenesulfonic acid 2-methoxy-1-propanol solution was slowly added, and the mixture was stirred at an internal temperature of 110°C for 8 hours. After cooling to room temperature, 600 g of methyl isobutyl ketone was added, and the organic layer was washed 5 times with 200 g of pure water, and then the organic layer was dried under reduced pressure. 320 g of THF was added to the residue, and 1350 g of methanol was used to reprecipitate the polymer. The precipitated polymer was separated by filtration and dried under reduced pressure to obtain a polymer (A8).

[0305] When the weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, the following results were obtained.

[0306] (A8): Mw=3,520, Mw / Mn=2.60

[0307] [Synthesis Example 9] Synthesis of polymer (A9)

[0308]

[0309] Under a nitrogen atmosphere, 100.0 g of compound (G6), 24.5 g of compound (G7) and 450 g of 1,2-dichloroethane were mixed and uniformly dispersed at an internal temperature of 60°C. Then, 64.1 g of methanesulfonic acid was added dropwise over 1 hour, and the mixture was heated and stirred at an internal temperature of 70°C for 24 hours. After cooling to room temperature, 1000 g of methyl isobutyl ketone was added, and the organic layer was washed 5 times with 200 g of pure water, and then the organic layer was dried under reduced pressure. 450 g of THF was added to the residue, and 1300 g of methanol was used to reprecipitate the polymer. The precipitated polymer was separated by filtration and dried under reduced pressure to obtain polymer (A9).

[0310] When the weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, the following results were obtained.

[0311] (A9): Mw=5,300, Mw / Mn=3.30

[0312] [Synthesis Example 10] Synthesis of polymer (A10)

[0313]

[0314] Under a nitrogen atmosphere, 50.0 g of compound (G6), 17.8 g of compound (G8), 3.0 g of p-toluenesulfonic acid, and 205 g of 2-methoxy-1-propanol were added, and a uniform solution was prepared at an internal temperature of 100° C. Then, 17.1 g of a 37% formalin aqueous solution was slowly added dropwise, and the mixture was stirred at an internal temperature of 110° C. for 8 hours. After cooling to room temperature, 500 g of methyl isobutyl ketone was added, and the organic layer was washed 5 times with 100 g of pure water, and then the organic layer was dried under reduced pressure. 210 g of THF was added to the residue, and 1260 g of hexane was used to reprecipitate the polymer. The precipitated polymer was separated by filtration and dried under reduced pressure to obtain a polymer (A10).

[0315] When the weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, the following results were obtained.

[0316] (A10): Mw=6,400, Mw / Mn=3.70

[0317] [Synthesis Example 11] Synthesis of polymer (A11)

[0318]

[0319] In a nitrogen atmosphere, 50.0 g of the compound (A8) obtained in Synthesis Example 8, 29.9 g of potassium carbonate, and 200 g of dimethylformamide were added to prepare a uniform dispersion at 50° C., and then 18.0 g of 3-bromo-1-propyne was slowly added dropwise, and stirred at an internal temperature of 50° C. for 8 hours. After cooling to room temperature, 300 ml of methyl isobutyl ketone and 200 g of pure water were added to the reaction solution to dissolve the precipitated salt, and the separated water layer was removed. Furthermore, the organic layer was washed 6 times with 100 g of a 3% nitric acid aqueous solution and 100 g of pure water, and then the organic layer was dried under reduced pressure to obtain a polymer (A11).

[0320] When the weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, the following results were obtained.

[0321] (A11): Mw=4,400, Mw / Mn=4.10

[0322] [Synthesis Example 12] Synthesis of Compound (R1) for Comparative Example

[0323]

[0324] Under a nitrogen atmosphere, 160.2 g of 1,5-dihydroxynaphthalene, 64.9 g of a 37% formaldehyde solution, and 300 g of 2-methoxy-1-propanol were added, and homogenized at an internal temperature of 100°C. Thereafter, 18.0 g of a 2-methoxy-1-propanol solution of 20% p-toluenesulfonic acid, which had been pre-mixed and homogenized, was slowly added, and the reaction was carried out at an internal temperature of 80°C for 8 hours. After the reaction was completed, it was cooled to room temperature, 1000 ml of methyl isobutyl ketone was added, and the mixture was washed 6 times with 200 ml of pure water, and the organic layer was dried under reduced pressure. After 300 g of THF was added to the residue to make a uniform solution, it was precipitated into 2000 g of hexane. The precipitated crystals were separated by filtration, washed twice with 500 g of hexane, and recovered. The recovered crystals were vacuum dried at 70°C to obtain a polymer (R1).

[0325] When the weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, the following results were obtained.

[0326] (R1): Mw=4,000, Mw / Mn=3.02

[0327] [Synthesis Example 13] Synthesis of Compound (R2) for Comparative Example

[0328]

[0329] Under a nitrogen atmosphere, 42.8 g of compound (G6), 15.7 g of potassium carbonate and 150 g of DMF were added to prepare a uniform dispersion at an internal temperature of 50°C. 28.2 g of 3-bromo-1-propyne was slowly added, and the reaction was carried out at an internal temperature of 50°C for 24 hours. 300 ml of methyl isobutyl ketone and 300 g of pure water were added to the reaction solution to dissolve the precipitated salt, and then the separated water layer was removed. Furthermore, the organic layer was washed 6 times with 100 g of 3% nitric acid aqueous solution and 100 g of pure water, and then the organic layer was dried under reduced pressure to obtain compound (R2).

[0330] When the weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, the following results were obtained.

[0331] (R2): Mw=560, Mw / Mn=1.01

[0332] [Synthesis Example 14] Synthesis of Compound (R3) for Comparative Example

[0333]

[0334] Under a nitrogen atmosphere, 41.2 g of compound (G9) and 160 g of dichloromethane were mixed. 19.2 g of methanesulfonic acid was slowly added dropwise, and the mixture was reacted under heating and reflux for 8 hours. After cooling to room temperature, 250 g of toluene was added, and the organic layer was washed 5 times with 100 g of pure water. The organic layer was dried under reduced pressure to obtain compound (R3).

[0335] When the weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, the following results were obtained.

[0336] (R3): Mw=1850, Mw / Mn=1.26

[0337] [Synthesis Example 15] Synthesis of Compound (R4) for Comparative Example

[0338]

[0339] Under a nitrogen atmosphere, 230.0 g of compound (G2), 20.0 g of compound (G10) and 1040 g of dichloromethane were added, and a uniform solution was prepared at an internal temperature of 35° C. Then, 9.0 g of trifluoromethanesulfonic acid and 0.6 g of 3-mercaptopropionic acid dissolved in 20.0 g of dichloromethane were added, and the mixture was reacted under heating and reflux for 4 hours. After cooling to room temperature, the organic layer was washed five times with 300 g of pure water. The organic layer was dried under reduced pressure to obtain compound (R4).

[0340] When the weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, the following results were obtained.

[0341] (R4): Mw=680, Mw / Mn=1.26

[0342] [Synthesis Example 16] Synthesis of Compound (R5) for Comparative Example

[0343]

[0344] Under nitrogen atmosphere, 20.0 g of the comparative example compound (R4) obtained in Synthesis Example 15, 32.0 g of potassium carbonate, and 62.0 g of acetone were added, and a uniform solution was prepared at 56° C. Then, 28.0 g of 3-bromo-1-propyne was slowly added to the reactor and stirred at 56° C. for 3 hours. The mixture was cooled to room temperature, and excess potassium carbonate and salt were removed by filtration, and the precipitate was washed with acetone. The organic layer was washed 5 times with 300 g of pure water. The organic layer was dried under reduced pressure to obtain compound (R5).

[0345] When the weight average molecular weight (Mw) and the degree of dispersion (Mw / Mn) were determined by GPC, the following results were obtained.

[0346] (R5): Mw=1,040, Mw / Mn=1.38

[0347] [Synthesis Example (C) Synthesis of Crosslinking Agent]

[0348] [Synthesis Example 17] Synthesis of Compound (C1)

[0349]

[0350] Under a nitrogen atmosphere, 500 mL of a 2.67 M hexane solution of n-butyl lithium was added to a mixed solution of 219.0 g of bis(4-bromophenyl) ether and 750 g of tert-butyl methyl ether, the internal temperature of which was cooled to -20°C, and the mixture was stirred at an internal temperature of -20°C for 20 minutes. 229.0 g of 9-fluorenone was added, the temperature was slowly raised to room temperature, and the mixture was stirred at room temperature for 4 hours. After adding 500 g of pure water to stop the reaction, the separated water layer was removed. Furthermore, after the organic layer was washed 5 times with 300 g of pure water, the organic layer was concentrated under reduced pressure, and 1000 g of hexane was added to precipitate crystals. The precipitated crystals were separated by filtration, washed twice with 500 g of hexane and recovered, and then dried under reduced pressure to obtain compound (C1).

[0351] (C1): Mw=540, Mw / Mn=1.02

[0352] [Resist underlayer film-forming composition (UDL-1)]

[0353] The resist underlayer film-forming polymer (A1) was dissolved in propylene glycol monomethyl ether acetate (PGMEA) containing 0.5 mass % of surfactant FC-4430 (manufactured by Sumitomo 3M Co., Ltd.) at the ratio shown in Table 2, and the mixture was filtered using a 0.02 μm membrane filter to prepare a resist underlayer film-forming composition (UDL-1).

[0354] [Preparation of Resist Underlayer Film-forming Compositions (UDL-2 to 15) and Resist Underlayer Film-forming Compositions for Comparative Examples (Comparative Examples UDL-1 to 5)]

[0355] Each chemical solution was prepared in the same manner as UDL-1 except that the type and content of each component were as shown in Table 2. It should be noted that in Table 2, "-" indicates that the corresponding component was not used. The crosslinking agent used the compound (C1) synthesized in the above-mentioned Synthesis Example 17 and the following formula (C2), the acid generator (TAG) used the following formula (E1), the high boiling point solvent used the following formula (B1), and the blending polymer used the following formula (BP1).

[0356] [Crosslinking agent]

[0357] The cross-linking agents used in the resist underlayer film-forming composition are shown below.

[0358]

[0359] [Acid generator]

[0360] The thermal acid generator (E1) used in the resist underlayer film-forming composition is shown below.

[0361]

[0362] [High boiling point solvent]

[0363] Table 1 shows the high boiling point solvent (B1) used in the resist underlayer film-forming composition.

[0364] [Table 1]

[0365]

[0366] [Polymer for blending]

[0367] The polymer for blending (BP1) used in the resist underlayer film-forming composition is shown below.

[0368]

[0369] (BP1): Mw=9,300, Mw / Mn=3.30

[0370] [Table 2]

[0371]

[0372] [Example 1: Film Thickness Evaluation]

[0373] The resist underlayer film forming composition prepared above (UDL-1 to 15, comparative examples UDL-1 to 5) was applied on a silicon substrate and fired at 250°C for 60 seconds. The film thickness from the center of the substrate to the periphery was measured and the average film thickness (a [nm]) was calculated.

[0374] In addition, separately from the above, a substrate heated at 250°C for 60 seconds was prepared and subjected to the following plasma treatment conditions to form a resist underlayer film. The film thickness from the center of the substrate to the periphery was measured, and the average film thickness (b [nm]) was calculated.

[0375] The thickness change of the resist underlayer film caused by plasma irradiation and the uniformity of the film thickness after plasma irradiation were evaluated. Regarding the uniformity of the film thickness, the film thickness of 225 points from the center of the substrate to the outer periphery of the 300 mm wafer was measured, and the case where the film thickness difference between the maximum film thickness and the minimum film thickness relative to the average film thickness (b) was less than 3% was set as "extremely good", the case where it was more than 3% and less than 5% was set as "good", and the case where it was more than 5% was set as "poor".

[0376] Additional treatment conditions (plasma treatment)

[0377] Each substrate heated at 250° C. for 60 seconds was subjected to plasma treatment under the following conditions using an etching apparatus Telius manufactured by Tokyo Electron Limited.

[0378] Plasma treatment conditions

[0379] Chamber pressure: 100mT

[0380] RF power (upper): 100W

[0381] RF power (lower): 3500W

[0382] H2 gas flow rate: 200sccm

[0383] Time: 20 seconds

[0384] The results are shown in Table 3.

[0385] [Table 3]

[0386]

[0387] ※Film thickness uniformityA…Extremely goodB…GoodC…Poor

[0388] As shown in Table 3, the resist underlayer film forming method of the present invention (Examples 1-1 to 1-15) can obtain a result with good uniformity of film thickness after plasma irradiation. The polymer contained in the resist underlayer film forming composition used in the present invention has the characteristic that the separation and rebonding of carbon bonds are easily promoted by plasma irradiation due to the structure of the fluorene skeleton containing high carbon density and repeated bonding by methylene groups. However, since it is a high molecular weight body containing a crosslinking group structure containing oxygen atoms and methylene groups, it can be inferred that the curability, density and heat resistance of the resist underlayer film are improved, the scattering of solid components in the film caused by plasma irradiation can be alleviated, and a resist underlayer film with small film thickness change before and after plasma irradiation and good film thickness uniformity can be formed. In particular, Examples 1-1, 1-2, 1-5, 1-6, 1-7, 1-8 and 1-11 obtained using the resist underlayer film forming composition containing a polymer in which k in the above formula (1) is 0 have good film thickness uniformity. It is presumed that when k in the above formula (1) is 1, the fluidity of the polymer can be improved, and thus it is effective in improving the planarization property. However, from the viewpoint of curability, k is preferably 0.

[0389] On the other hand, in Comparative Example 1-1, the film thickness before and after plasma irradiation changes greatly compared with the example. In addition, in Comparative Examples 1-2 to 1-5, the film thickness difference before and after plasma irradiation is large, and the film thickness uniformity of the resist lower layer film after plasma irradiation is insufficient. It is believed that in these comparative examples, since oligomers or compounds without methylene groups are used, the curability of the resist lower layer film before the additional treatment is insufficient, and not only the separation and rebonding of carbon bonds are performed, but also the scattering of solid components in the film is actively generated. Therefore, it can be inferred that the film thickness before and after plasma irradiation changes greatly, and the film thickness uniformity after plasma irradiation is insufficient.

[0390] [Example 2: Etching resistance evaluation]

[0391] The resist underlayer film-forming composition prepared above (UDL-1 to 15, comparative example UDL-1 to 5) was applied to a silicon substrate, and after calcining at 250°C for 60 seconds, the film thickness from the center of the substrate to the periphery was measured, and the average film thickness (c [nm]) was calculated. Next, etching was performed using CF4 gas using an etching device Telius manufactured by Tokyo Electron Limited under the following conditions, and the film thickness d was measured. The film thickness etched in 1 minute was calculated from the film thickness (film thickness c - film thickness d) etched during a specified period of time using CF4 gas as an etching rate A (nm / min). The results are shown in Table 4.

[0392] In addition, separately from the above, a substrate heated at 250°C for 60 seconds was prepared, and the following plasma treatment conditions were respectively performed to form a resist lower layer film, and the film thickness e was measured. Next, using the etching device Telius manufactured by Tokyo Electron Limited and the following conditions, CF4 gas was used for etching, and the film thickness f was measured. The film thickness etched within 1 minute was calculated from the film thickness (film thickness e-film thickness f) etched during a specified time period using CF4 gas as the etching rate B (nm / min). The smaller the number of the etching rate, the better the etching resistance for CF4 gas.

[0393] The etching resistance of the film after the additional treatment was compared with that of the film fired at 250° C., and the effect of improving the etching resistance by the additional treatment was calculated (etching rate A (nm / min)−etching rate B (nm / min)).

[0394] The etching conditions are as follows.

[0395] Dry etching conditions based on CF4 gas

[0396] Chamber pressure: 100mT

[0397] RF power (upper): 500W

[0398] RF power (lower): 400W

[0399] CF4 gas flow rate: 300sccm

[0400] Time: 30 seconds

[0401] The additional treatment conditions (plasma irradiation) were the same as those in Example 1.

[0402] [Table 4]

[0403]

[0404] As shown in Table 4, in the resist underlayer film forming method of the present invention (Examples 1-1 to 1-15), the result of greatly improving the dry etching resistance to CF4 gas by plasma irradiation can be obtained. The polymer contained in the resist underlayer film forming composition used in the present invention is a high molecular weight body containing a fluorene skeleton with a high carbon density in the repeating unit. Therefore, it can be considered that: by plasma irradiation, the carbon bonds of the resist underlayer film are separated and re-bonded, and it is easy to reconstruct in the form of a cured film with a diamond-like carbon structure, showing excellent dry etching resistance. In particular, Examples 2-2, 2-5, 2-6, 2-8 and 2-11 using polymers in which k in the above formula (1) is 0 and Ar1 and Ar2 are benzene have good dry etching resistance, and further, Example 2-2 using a polymer in which n1 in the above formula (1A) is 0 and R2 is a hydrogen atom shows extremely good results. The polymer (A2) used in Example 2-2 has a large proportion of the fluorene skeleton contained in the repeating unit. Therefore, plasma irradiation can easily promote the separation and re-bonding of the carbon bonds of the resist lower layer film. Furthermore, the proportion of the cross-linking groups (hydroxyl and methylene) contained in the repeating unit is also large. Therefore, it can be inferred that the density of the resist lower layer film is further improved by plasma irradiation, showing good dry etching resistance.

[0405] The polymer of Comparative Example 2-1 does not contain a fluorene skeleton in the repeating unit, so it can be inferred that the modification of the resist underlayer film by plasma irradiation is insufficient. Comparative Example 2-2 contains a fluorene skeleton and is a compound rather than a polymer, so it can be inferred that the curability of the resist underlayer film before plasma irradiation is insufficient, and the carbon bonds are separated and rebonded by plasma irradiation, and the solid components in the resist underlayer film are scattered, and the film modification is not sufficiently performed by plasma irradiation. Comparative Example 2-3 is a polymer containing a fluorene skeleton, but it is a structure without a methylene group and has a small molecular weight, so it can be inferred that the curability of the resist underlayer film before plasma irradiation is insufficient, and the carbon bonds are separated and rebonded by plasma irradiation, and the solid components in the resist underlayer film are scattered, and the film modification is not sufficiently performed by plasma irradiation. Comparative Examples 2-4 and 2-5 are structures containing a fluorene skeleton but no methylene group, and are oligomers. Therefore, it can be inferred that the curing property of the resist underlayer film before plasma irradiation is insufficient, and the carbon bonds are separated and re-bonded by plasma irradiation. At the same time, the solid components in the resist underlayer film are scattered, and the film modification is not fully carried out by plasma irradiation.

[0406] From the above results, it can be seen that in order to achieve a high balance between modification of the resist underlayer film by plasma irradiation and film thickness uniformity, the structures of the fluorene skeleton and the methylene group are important, and a polymer in which the structure including the fluorene skeleton is connected via the methylene group is preferred.

[0407] [Example 3: Flatness Evaluation]

[0408] The above-mentioned resist underlayer film-forming compositions (UDL-1 to 15 and comparative examples UDL-1 to 5) were coated on SiO2 wafer substrates having a dense line & space pattern (line width of 40 nm, line depth of 120 nm, and center-to-center distance of two adjacent lines of 80 nm), and fired at 250°C for 60 seconds to form a resist underlayer film with a film thickness of 100 nm. Thereafter, the same plasma irradiation treatment as in the above-mentioned dry etching resistance evaluation was performed.

[0409] The substrate used is Figure 2 The base substrate 7 (SiO2 wafer substrate) having a dense line & space pattern as shown in (G) (top view) and (H) (cross-sectional view). Figure 2 As shown in (I), the pattern is filled with the resist underlayer film 8. Then, plasma irradiation treatment is performed, and the cross-sectional shape of each wafer substrate obtained is observed using an electron microscope (S-4700) manufactured by Hitachi, Ltd., as shown in FIG. Figure 3 As shown in (T) and (U) of FIG. 1 , the height difference Delta 10 of the resist lower layer film (filling film) 10 between the line pattern dense part and the non-line pattern forming part in the base substrate 9 is evaluated. In this evaluation, the smaller the height difference, the better the flattening property. The results are shown in Table 5.

[0410] [Table 5]

[0411]

[0412] As shown in Table 5, it was confirmed that the resist underlayer film-forming composition (UDL-1 to 15) of the present invention can provide a resist underlayer film having excellent planarization characteristics even after plasma irradiation. On the other hand, it was confirmed that the planarization characteristics of Comparative Examples 3-1 to 3-5 obtained using Comparative Examples UDL-1 to 5 in which a large change in film thickness before and after plasma irradiation was confirmed in Example 1 were insufficient.

[0413] [Example 4: Pattern Formation Method]

[0414] The resist underlayer film-forming compositions (UDL-1 to 15 and comparative examples UDL-1 to 5) were coated on a silicon wafer substrate on which a SiO2 film having a groove pattern (groove width of 10 μm and groove depth of 0.10 μm) was formed, and fired at 250° C. for 60 seconds in the atmosphere to form an underlayer film precursor film having a film thickness of 100 nm. Thereafter, the same plasma irradiation treatment as in the dry etching resistance evaluation was performed.

[0415] In Comparative Example 4-6, UDL-1 was applied on a silicon wafer substrate having a SiO2 film formed thereon, and fired in air at 250°C for 60 seconds to form a resist underlayer film having a thickness of 100 nm. The resist underlayer film was not irradiated with plasma.

[0416] A resist interlayer material (SOG-1) containing silicon atoms was coated on the resist lower layer film prepared by the above method, and baked at 220°C for 60 seconds to form a resist interlayer film with a film thickness of 20 nm. A single-layer resist for ArF, which was a resist upper layer material, was coated thereon, and baked at 105°C for 60 seconds to form a photoresist film with a film thickness of 100 nm. A liquid immersion protective film material (TC-1) was coated on the photoresist film, and baked at 90°C for 60 seconds to form a protective film with a film thickness of 50 nm.

[0417] A polymer represented by an ArF silicon-containing intermediate film polymer (SiP1) as an anti-etching intermediate layer material (SOG-1) containing silicon atoms and a cross-linking catalyst (CAT1) are dissolved in an organic solvent containing 0.1% by mass of FC-4430 (manufactured by Sumitomo 3M Co., Ltd.) in the proportions shown in Table 6, and filtered using a fluororesin filter with a pore size of 0.1 μm to prepare an anti-etching intermediate layer material (SOG-1) containing silicon atoms.

[0418] [Table 6]

[0419]

[0420] The structural formulas of the ArF silicon-containing interlayer polymer (SiP1) and the crosslinking catalyst (CAT1) used are shown below.

[0421]

[0422] As a resist upper film material (single-layer resist for ArF), a polymer (RP1), an acid generator (PAG1), and a basic compound (Amine1) are dissolved in a solvent containing 0.1% by mass of a surfactant FC-4430 (manufactured by Sumitomo 3M Co., Ltd.) in the proportions shown in Table 7, and the material is prepared by filtering using a 0.1 μm fluororesin filter.

[0423] [Table 7]

[0424]

[0425] The polymer (RP1), the acid generator (PAG1), and the basic compound (Amine1) used in the resist upper layer film material (ArF single-layer resist) are shown below.

[0426]

[0427]

[0428] As the liquid immersion protective film material (TC-1), the protective film polymer (PP1) was dissolved in an organic solvent at a ratio in Table 8, and the solution was filtered through a 0.1 μm fluororesin filter to prepare the liquid immersion protective film material (TC-1).

[0429] [Table 8]

[0430]

[0431] The polymer (PP1) used for the liquid immersion protective film material (TC-1) is shown below.

[0432]

[0433] Next, exposure was performed using an ArF liquid immersion exposure device (manufactured by Nikon; NSR-S610C, NA of 1.30, σ of 0.98 / 0.78, 35-degree dipole s-polarized illumination, 6% halftone phase shift mask), baked at 100°C for 60 seconds (PEB), and developed using a 2.38% by mass tetramethylammonium hydroxide (TMAH) aqueous solution for 30 seconds to obtain a 40nm 1:1 positive line and space pattern (resist pattern).

[0434] Next, using an etching device Telius manufactured by Tokyo Electron Limited, a resist intermediate layer material (SOG-1) containing silicon atoms is etched by dry etching using a resist pattern as a mask to form a hard mask pattern, and the resist lower film is etched using the obtained SOG-1 pattern as a mask to form a resist lower film pattern, and the SiO2 film is etched using the obtained resist lower film pattern as a mask. The etching conditions are as follows.

[0435] Conditions for transferring a resist pattern to a resist intermediate layer material containing silicon atoms (SOG-1).

[0436] Chamber pressure: 50mT

[0437] RF power (upper): 500W

[0438] RF power (lower): 300W

[0439] CF4 gas flow rate: 150sccm

[0440] CHF3 gas flow rate: 50sccm

[0441] Time: 15 seconds

[0442] Conditions for transferring a resist intermediate layer material (SOG-1) pattern containing silicon atoms to a resist underlayer film.

[0443] Chamber pressure: 10mT

[0444] RF power (upper): 1,000W

[0445] RF power (lower): 300W

[0446] CO2 gas flow rate: 320sccm

[0447] N2 gas flow rate: 80sccm

[0448] Time: 55sec

[0449] Conditions for transferring the resist underlayer film pattern to the SiO2 film.

[0450] Chamber pressure: 100mT

[0451] RF power (upper): 500W

[0452] RF power (lower): 300W

[0453] CF4 gas flow rate: 150sccm

[0454] CHF3 gas flow rate: 30sccm

[0455] O2 gas flow rate: 10sccm

[0456] Time: 130 seconds

[0457] Table 9 shows the results of observing the pattern cross section using an electron microscope (S-4700) manufactured by Hitachi, Ltd.

[0458] [Table 9]

[0459]

[0460] As shown in Table 9, it was confirmed that in Examples 4-1 to 4-15 using the resist underlayer film-forming composition (UDL-1 to 15) of the present invention, the resist upper film pattern was finally well transferred to the substrate to be processed in any case, and the resist underlayer film forming method of the present invention can be suitably used for microfabrication based on the multilayer resist method. On the other hand, according to the above-mentioned etching resistance evaluation, it was observed that in Comparative Examples 4-2 to 4-5 obtained using Comparative Examples UDL-2 to 5, which were confirmed to have insufficient etching resistance compared with the resist underlayer film forming method of the present invention, the pattern shape after substrate transfer etching was distorted. In addition, it was observed that Comparative Example 4-1 obtained using Comparative Example UDL-1, which had extremely insufficient etching resistance, and Comparative Example 4-6, which was not irradiated with plasma, had no pattern remaining, and the pattern was not transferred to the substrate to be processed due to insufficient etching resistance of the resist underlayer film.

[0461] In summary, the resist underlayer film forming method of the present invention can form a resist underlayer film with excellent film thickness uniformity and excellent dry etching resistance during substrate processing by plasma irradiation, and is therefore extremely useful in the next generation of micro-processing technology. In addition, it is clear that the pattern forming method of the present invention performed using the method can form a fine pattern with high precision even if the object to be processed is a substrate with a height difference.

[0462] This specification includes the following technical solutions.

[0463] [1]: A method for forming a resist underlayer film, characterized in that it is a method for forming a resist underlayer film on a substrate, comprising the following steps: (i) a step of coating a resist underlayer film forming composition comprising (A) a polymer and (B) an organic solvent on the aforementioned substrate, and curing the composition by heat treatment at a temperature of not less than 100°C and not more than 800°C for 10 seconds to 7,200 seconds to form an underlayer film precursor film; and (ii) a step of plasma irradiating the substrate on which the aforementioned underlayer film precursor film is formed to form a resist underlayer film, wherein the aforementioned (A) polymer comprises a structural unit represented by the following general formula (1) and has a weight average molecular weight in terms of polystyrene based on gel permeation chromatography of 2,500 to 20,000.

[0464]

[0465] (In the formula, Ar1 and Ar2 are independently substituted or unsubstituted benzene rings or substituted or unsubstituted naphthalene rings, X is a structure represented by the following general formula (1A), Y is a divalent organic group having 6 to 50 carbon atoms, and k is 0 or 1.)

[0466]

[0467] (In the formula, n1 is 0 or 1, n2 is 1 or 2, R2 is a hydrogen atom, an organic group having 1 to 10 carbon atoms, or any one of the structures represented by the following general formula (1B). R3 is a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a group represented by the following general formula (1C), n3 is 0, 1 or 2, * is a bonding portion bonded to a methylene group, and ** is a bonding portion bonded to a quaternary carbon of fluorene.)

[0468]

[0469] (where * represents the bonding site to the oxygen atom, R A is a divalent organic group having 1 to 10 carbon atoms, R B It is a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms.

[0470]

[0471] (In the formula, R4 is a hydrogen atom or a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms, and the hydrogen atoms on the benzene ring in the formula may be optionally replaced by a methyl group or a methoxy group.)

[0472] [2]: The resist underlayer film forming method according to [1] above, characterized in that in the general formula (1), Y is any one of the structures represented by the following formula (Y-1).

[0473]

[0474] (The hydrogen atoms in the above structure may be substituted with a hydroxyl group or a monovalent organic group having 1 to 10 carbon atoms.)

[0475] [3]: The method for forming a resist underlayer film according to the above [1] or [2], characterized in that in the above general formula (1A), R2 is a hydrogen atom.

[0476] [4]: A method for forming an anti-etching underlayer film according to any one of [1] to [3] above, characterized in that in the general formula (1A), R2 is a hydrogen atom or a structure represented by the general formula (1B), and in the structure constituting the above R2, when the proportion of hydrogen atoms is set to a and the proportion of the structure represented by the general formula (1B) is set to b, the relationship a+b=1 and 0.1≤b≤0.9 is satisfied.

[0477] [5]: A method for forming an anti-etching agent underlayer film according to any one of [1] to [4] above, characterized in that in the general formula (1), Ar1 and Ar2 are unsubstituted benzene rings, and in the general formula (1A), n1 is 0, n2 is 1 or 2, and n3 is 0.

[0478] [6]: The method for forming a resist underlayer film according to any one of [1] to [5] above, wherein in the general formula (1), k is 0.

[0479] [7]: The method for forming a resist underlayer film according to any one of [1] to [6] above, wherein the weight average molecular weight of the polymer (A) as measured by gel permeation chromatography in terms of polystyrene is 7,000 to 15,000.

[0480] [8]: The method for forming a resist underlayer film according to any one of [1] to [7] above, characterized in that the resist underlayer film forming composition further contains one or more of (C) a crosslinking agent, (D) a surfactant, (E) an acid generator and (F) a plasticizer.

[0481] [9]: A method for forming an anti-etching underlayer film according to any one of [1] to [8] above, characterized in that the aforementioned (B) organic solvent is set to a mixture of one or more organic solvents having a boiling point lower than 180 degrees and one or more organic solvents having a boiling point of more than 180 degrees, namely (B-1) a high boiling point solvent.

[0482]

[10] : A method for forming a resist underlayer film according to any one of [1] to [9] above, characterized in that in the step (ii), the plasma irradiation is carried out in an atmosphere of N2, NF3, H2, fluorocarbons, rare gases or a mixture of any of them.

[0483]

[11] : The method for forming a resist underlayer film according to any one of [1] to

[10] above, characterized in that in the step (i), the heat treatment is performed in an atmosphere having an oxygen concentration of not less than 1% and not more than 21%.

[0484]

[12] : The method for forming a resist underlayer film according to any one of [1] to

[10] above, characterized in that in the step (i), the heat treatment is performed in an atmosphere having an oxygen concentration of less than 1%.

[0485]

[13] : A pattern forming method, characterized in that it is a method for forming a pattern on a processed substrate, comprising the following steps: (I-1) a step of forming a resist lower layer film on the processed substrate by the resist lower layer film forming method described in any one of [1] to

[12] above; (I-2) a step of forming a resist intermediate film on the aforementioned resist lower layer film; (I-3) a step of forming a resist upper layer film on the aforementioned resist intermediate film using a photoresist material; (I-4) pattern exposing the aforementioned resist upper layer film. (I-5) a process of transferring the pattern to the aforementioned resist intermediate film by dry etching using the resist upper film having the aforementioned pattern formed thereon as a mask; (I-6) a process of transferring the pattern to the aforementioned resist lower film by dry etching using the resist intermediate film having the aforementioned pattern transferred thereon as a mask; and (I-7) a process of processing the aforementioned processed substrate by using the resist lower film having the aforementioned pattern formed thereon as a mask to form a pattern on the aforementioned processed substrate.

[0486]

[14] : A pattern forming method, characterized in that it is a method for forming a pattern on a processed substrate, comprising the following steps: (II-1) a step of forming a resist underlayer film on a processed substrate having a height difference by using the resist underlayer film forming method described in any one of [1] to

[12] above; (II-2) a step of forming a resist upper layer film on the upper layer of the aforementioned resist underlayer film; (II-3) a step of exposing the aforementioned resist upper layer film to a pattern and then developing it with a developer to form a pattern on the aforementioned resist upper layer film; (II-4) a step of transferring the pattern to the aforementioned resist underlayer film by dry etching using the resist upper layer film formed with the aforementioned pattern as a mask; (II-5) a step of processing the aforementioned processed substrate using the resist underlayer film formed with the aforementioned pattern as a mask to form a pattern on the aforementioned processed substrate.

[0487]

[15] : The pattern forming method according to

[13] or

[14] above, characterized in that the aspect ratio of the height difference of the processed substrate is set to 3 or more.

[0488] It should be noted that the present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments are for illustration only, and any technical solutions having substantially the same structure and exerting the same effects as the technical concept described in the claims of the present invention fall within the scope of the present invention.

Claims

1. A method for forming a resist underlayer film, characterized in that: The invention relates to a method for forming a resist lower layer film on a substrate, comprising the following steps: (i) a step of coating a resist underlayer film-forming composition comprising (A) a polymer and (B) an organic solvent on the substrate, and curing the composition by heat treatment at a temperature of 100° C. to 800° C. for 10 seconds to 7,200 seconds to form an underlayer film precursor film; and (ii) a step of irradiating the substrate having the underlayer film precursor film formed thereon with plasma to form a resist underlayer film, The polymer (A) comprises a structural unit represented by the following general formula (1), and has a weight average molecular weight of 2,500 to 20,000 in terms of polystyrene based on gel permeation chromatography. In formula (1), Ar1 and Ar2 are independently substituted or unsubstituted benzene rings or substituted or unsubstituted naphthalene rings, X is a structure represented by the following general formula (1A), Y is a divalent organic group having 6 to 50 carbon atoms, k is 0 or 1, In formula (1A), n1 is 0 or 1, n2 is 1 or 2, R2 is a hydrogen atom, an organic group having 1 to 10 carbon atoms, or any one of the structures represented by the following general formula (1B), R3 is a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, or a group represented by the following general formula (1C), n3 is 0, 1 or 2, * is a bonding portion bonded to a methylene group, ** is a bonding portion bonded to a quaternary carbon of fluorene, In formula (1B), * represents a bonding site to an oxygen atom, and R A is a divalent organic group having 1 to 10 carbon atoms, R B is a hydrogen atom or a monovalent organic group having 1 to 10 carbon atoms, In the formula (1C), R4 is a hydrogen atom or a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms, and the hydrogen atom on the benzene ring in the formula may be substituted with a methyl group or a methoxy group.

2. The resist underlayer film forming method according to claim 1, wherein: In the general formula (1), Y is any one of the structures represented by the following formula (Y-1), The hydrogen atoms in the above structure may be substituted with a hydroxyl group or a monovalent organic group having 1 to 10 carbon atoms.

3. The resist underlayer film forming method according to claim 1, wherein: In the general formula (1A), R2 is a hydrogen atom.

4. The resist underlayer film forming method according to claim 1, wherein: In the general formula (1A), R2 is a hydrogen atom or a structure represented by the general formula (1B). When the ratio of hydrogen atoms in the structure of R2 is set to a and the ratio of the structure represented by the general formula (1B) is set to b, the relationship a+b=1 and 0.1≤b≤0.9 is satisfied.

5. The resist underlayer film forming method according to claim 1, wherein: In the general formula (1), Ar1 and Ar2 are unsubstituted benzene rings. In the general formula (1A), n1 is 0, n2 is 1 or 2, and n3 is 0.

6. The resist underlayer film forming method according to claim 1, wherein: In the general formula (1), k is 0.

7. The resist underlayer film forming method according to claim 1, wherein: The (A) polymer has a polystyrene-equivalent weight average molecular weight of 7,000 to 15,000 based on gel permeation chromatography.

8. The resist underlayer film forming method according to claim 1, wherein: The resist underlayer film-forming composition further contains one or more of (C) a crosslinking agent, (D) a surfactant, (E) an acid generator, and (F) a plasticizer.

9. The resist underlayer film forming method according to claim 1, wherein: The (B) organic solvent is a mixture of one or more organic solvents having a boiling point of less than 180 degrees and one or more organic solvents having a boiling point of 180 degrees or more, that is, (B-1) a high boiling point solvent.

10. The resist underlayer film forming method according to any one of claims 1 to 9, wherein: In the step (ii), the plasma irradiation is performed in an atmosphere of N2, NF3, H2, fluorocarbon, rare gas or a mixture of any of them.

11. The resist underlayer film forming method according to any one of claims 1 to 9, wherein: In the step (i), the heat treatment is performed in an atmosphere having an oxygen concentration of 1% to 21%.

12. The resist underlayer film forming method according to any one of claims 1 to 9, wherein: In the step (i), the heat treatment is performed in an atmosphere having an oxygen concentration of less than 1%.

13. A pattern forming method, characterized in that: The method is a method for forming a pattern on a processed substrate, comprising the following steps: (I-1) a step of forming a resist underlayer film on a substrate to be processed by the resist underlayer film forming method according to any one of claims 1 to 9; (I-2) a step of forming a resist intermediate film on the resist underlayer film; (I-3) a step of forming a resist upper layer film on the resist intermediate film using a photoresist material; (I-4) a step of exposing the resist upper layer film to pattern exposure and then developing the resist upper layer film with a developer to form a pattern on the resist upper layer film; (I-5) a step of transferring the pattern to the resist intermediate film by dry etching using the resist upper layer film having the pattern formed thereon as a mask; (I-6) a step of transferring the pattern to the resist underlayer film by dry etching using the resist intermediate film to which the pattern is transferred as a mask; as well as (I-7) A step of processing the substrate to be processed using the resist underlayer film having the pattern formed thereon as a mask to form a pattern on the substrate to be processed.

14. A pattern forming method, characterized in that: The method is a method for forming a pattern on a processed substrate, comprising the following steps: (II-1) a step of forming a resist underlayer film on a substrate to be processed having a height difference by the resist underlayer film forming method according to any one of claims 1 to 9; (II-2) forming a resist upper layer film on the upper layer of the resist lower layer film; (II-3) a step of exposing the resist upper layer film to pattern exposure and then developing the resist upper layer film with a developer to form a pattern on the resist upper layer film; (II-4) a step of transferring the pattern to the resist lower film by dry etching using the resist upper film having the pattern formed thereon as a mask; (II-5) A step of processing the substrate to be processed using the resist underlayer film having the pattern formed thereon as a mask to form a pattern on the substrate to be processed.

15. The pattern forming method according to claim 14, characterized in that: The aspect ratio of the height difference of the processed substrate is set to 3 or more.

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