Method for manufacturing semiconductor substrate and composition for forming resist underlayer film

Abstract

The purpose of the present invention is to provide: a method for producing a semiconductor substrate that has excellent pattern rectangularity; and a composition for forming a resist underlayer film. A method for producing a semiconductor substrate, the method comprising: a step in which a composition for forming a resist underlayer film is directly or indirectly applied to a substrate; a step in which a metal-containing resist film is formed on a resist underlayer film that is formed by the above-described step for applying a composition for forming a resist underlayer film; a step in which the metal-containing resist film is exposed to light; and a step in which a resist pattern is formed by volatilizing a part of the light-exposed metal-containing resist film.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a semiconductor substrate and a composition for forming an underlayer film of a resist.

Background Art

[0002] In a general pattern formation method used for microfabrication by lithography, a resist film formed from a radiation-sensitive composition for forming a resist film is exposed to electromagnetic waves such as far ultraviolet rays (e.g., ArF excimer laser light, KrF excimer laser light, etc.), extreme ultraviolet rays (EUV), or charged particle beams such as electron beams to generate acid in the exposed areas. Then, a difference in the dissolution rate with respect to a developer is caused between the exposed areas and the unexposed areas by a chemical reaction using this acid as a catalyst, and a pattern is formed on the substrate. The formed pattern can be used as a mask or the like in substrate processing. With such a pattern formation method, it is required to improve the resist performance as the miniaturization of processing technology progresses. In response to this requirement, the types, molecular structures, etc. of the organic polymer, acid generator, and other components used in the radiation-sensitive composition for forming a resist film have been studied, and furthermore, their combinations have also been studied in detail (see Japanese Patent Application Laid-Open No. 2000-298347). Also, using a metal-containing compound instead of an organic polymer has been studied.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the resist pattern formed using the above-described metal-containing compound, the resist pattern may fall over or the pattern may be pulled at the bottom of the resist film.

[0005] An object of the present invention is to provide a method for manufacturing a semiconductor substrate and a composition for forming a resist underlayer film that can suppress the collapse of a resist pattern and the trailing of the pattern at the bottom of the resist film, and form a resist pattern with excellent pattern rectangularity.

Means for Solving the Problems

[0006] In one embodiment, the present invention A step of applying a composition for forming a resist underlayer film directly or indirectly on a substrate; A step of forming a metal-containing resist film on the resist underlayer film formed by the step of applying the composition for forming a resist underlayer film; A step of exposing the metal-containing resist film; A step of forming a resist pattern by volatilizing a part of the exposed metal-containing resist film and relates to a method for manufacturing a semiconductor substrate.

[0007] In another embodiment, the present invention A step of applying a composition for forming a resist underlayer film directly or indirectly on a substrate; A step of forming a metal-containing resist film on the resist underlayer film formed by the step of applying the composition for forming a resist underlayer film; A step of exposing the metal-containing resist film; A composition for forming a resist underlayer film used in a method for manufacturing a semiconductor substrate, comprising: At least one selected from the group consisting of an acid generating component, an acid group-containing component, a photo base generator, and a base-containing component; A solvent and relates to a composition for forming a resist underlayer film.

Effects of the Invention

[0008] According to the method for manufacturing the semiconductor substrate, since a composition for forming a resist underlayer film capable of forming a resist underlayer film excellent in resist pattern rectangularity is used, a semiconductor substrate having a good pattern shape can be efficiently manufactured. According to the composition for forming a resist underlayer film, since a resist underlayer film excellent in resist pattern rectangularity can be formed, a semiconductor substrate having a good pattern shape can be efficiently manufactured. Therefore, the method for manufacturing the semiconductor substrate and the composition for forming a resist underlayer film can be suitably used for manufacturing semiconductor devices and the like that are expected to further progress in miniaturization in the future.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, the method for manufacturing a semiconductor substrate and the composition for forming a resist underlayer film according to each embodiment of the present invention will be described in detail.

[0010] 《Method for Manufacturing a Semiconductor Substrate》 The method for manufacturing the semiconductor substrate includes a step of coating a composition for forming a resist underlayer film directly or indirectly on a substrate (hereinafter, also referred to as "resist underlayer film forming composition coating step"), and a step of forming a metal-containing resist film on the resist underlayer film formed by the resist underlayer film forming composition coating step (hereinafter, also referred to as "metal-containing resist film forming step"), a step of exposing the metal-containing resist film (hereinafter, also referred to as "exposure step"), and a step of forming a resist pattern by volatilizing a part of the exposed metal-containing resist film (hereinafter, also referred to as "resist pattern forming step").

[0011] Hereinafter, each step of the method for manufacturing the semiconductor substrate will be described.

[0012] [Resist Underlayer Film Forming Composition Coating Step] In this process, the composition for forming a resist underlayer film is applied directly or indirectly onto the substrate. The method of applying the composition for forming a resist underlayer film is not particularly limited, and it can be carried out by an appropriate method such as spin coating, casting, roll coating, etc. Thereby, a coating film is formed, and a resist underlayer film is formed by volatilization of the solvent in the composition for forming a resist underlayer film. The composition for forming a resist underlayer film will be described later.

[0013] Next, the coating film formed by the above application is heated. Heating of the coating film promotes the formation of the resist underlayer film. More specifically, heating of the coating film promotes volatilization of the solvent in the composition for forming a resist underlayer film.

[0014] The heating of the above coating film may be carried out in an air atmosphere or in a nitrogen atmosphere. As the lower limit of the heating temperature, 100 °C is preferable, 150 °C is more preferable, and 200 °C is even more preferable. As the upper limit of the above heating temperature, 400 °C is preferable, 350 °C is more preferable, and 280 °C is even more preferable. As the lower limit of the time in heating, 15 seconds is preferable, and 30 seconds is more preferable. As the upper limit of the above time, 1,200 seconds is preferable, and 600 seconds is more preferable.

[0015] As the lower limit of the average thickness of the formed resist underlayer film, 0.5 nm is preferable, 1 nm is more preferable, and 2 nm is even more preferable. As the upper limit of the above average thickness, 50 nm is preferable, 20 nm is more preferable, 10 nm is even more preferable, and 7 nm is particularly preferable. The method for measuring the average thickness is according to the description in the examples.

[0016] [Metal-Containing Resist Film Formation Step] In this step, a metal-containing resist film is formed on the resist underlayer film formed by the above resist underlayer film forming composition application step.

[0017] The metal-containing resist film can be formed by depositing a metal compound on the above resist underlayer film.

[0018] The deposition of the metal compound on the resist underlayer film may be carried out by vapor deposition such as chemical vapor deposition (CVD) or atomic layer deposition (ALD). The vapor deposition may be carried out by plasma-enhanced (PE)CVD or plasma-enhanced (PE)ALD.

[0019] The metal atoms contained in the metal-containing resist film are preferably at least one selected from the group consisting of Sn and Hf.

[0020] Examples of the metal compound include the metal compound represented by the following formula (1). M(X)4(1) (In formula (1), M is Sn or Hf. X is each independently a halogen atom or an alkyl group.)

[0021] Examples of the metal compound include Sn(CH3)4, Sn(Br)4, HfCl4, etc. Two or more metal compounds can be used in combination.

[0022] For example, the process conditions suitable for the deposition of Sn(CH3)4 on the resist underlayer film include a deposition temperature between about -54°C and 30°C (for example, about 20°C) and a reactor pressure of 20 Torr or less (for example, a pressure maintained at about 1 Torr at 20°C). By maintaining the flow rate of Sn(CH3)4 between about 100 sccm and 1000 sccm, the deposition rate can be controlled.

[0023] For example, the process conditions suitable for the deposition of HfCl4 on the resist underlayer film include a deposition temperature between about 0°C and 300°C (for example, about 100°C) and a reactor pressure of 10 Torr or less (for example, a pressure maintained between 0.1 and 1 Torr at 100°C). By maintaining the flow rate of HfCl4 between about 10 sccm and 100 sccm, the deposition rate can be controlled.

[0024] The Sn(Br)4 film can be made into a SnX4 film by the reaction of the following formula with the reactant X2 (for example, when X is Cl, I, or H). SnBr4 + X2 → SnX4 + 2Br2

[0025] The film of HfCl4 can be converted into a film of HfX4 by reaction with a reactant X2 (for example, when X is Br, I, or H) according to the following formula. HfCl4 + X2 → HfX4 + 2Cl2

[0026] As the lower limit of the average thickness of the formed metal-containing resist film, 0.1 nm is preferable, 0.5 nm is more preferable, and 1 nm is even more preferable. As the upper limit of the above average thickness, 50 nm is preferable, 20 nm is more preferable, 10 nm is even more preferable, and 5 nm is particularly preferable. The method for measuring the average thickness is as described in the examples.

[0027] [Exposure step] In this step, the metal-containing resist film formed in the above metal-containing resist film forming step is exposed.

[0028] The radiation used for exposure can be appropriately selected according to the type of the metal-containing resist film to be used, etc. For example, electromagnetic waves such as visible light, ultraviolet light, far ultraviolet light, X-rays, γ-rays, and particle beams such as electron beams, molecular beams, and ion beams can be mentioned. Among these, far ultraviolet light is preferable, and KrF excimer laser light (wavelength 248 nm), ArF excimer laser light (wavelength 193 nm), F2 excimer laser light (wavelength 157 nm), Kr2 excimer laser light (wavelength 147 nm), ArKr excimer laser light (wavelength 134 nm), or extreme ultraviolet light (wavelength 13.5 nm, etc., also referred to as "EUV") is more preferable, and EUV is even more preferable. Also, the exposure conditions can be appropriately determined according to the type of the metal-containing resist film to be used, etc.

[0029] For example, EUV decomposes the metal compound (including the above SnX4 and HfX4) in the exposed portion of the metal-containing resist film. For example, when the metal compound is Sn(Br)4, the decomposition reaction of the metal compound proceeds as follows. SnBr4 → Sn + 2Br2 EUV directly decomposes SnBr4 into Sn and bromine gas (Br2).

[0030] When the metal compound is Sn(CH3)4, the decomposition reaction of the metal compound by EUV proceeds as follows: Sn(CH3)4 → Sn + 2C2H6

[0031] When the metal compound is HfCl4, the decomposition reaction of the metal compound by EUV proceeds as follows: HfCl4 → Hf + 2Cl2

[0032] [Resist Pattern Formation Step] In this step, a part of the exposed metal-containing resist film is volatilized to form a resist pattern.

[0033] A resist pattern can be formed by volatilizing the unexposed portion of the exposed metal-containing resist film. The volatilization of the unexposed portion of the exposed metal-containing resist film can be performed by reducing the pressure, heating, or a combination thereof.

[0034] For example, in the case of a metal-containing resist film formed by the deposition of Sn(CH3)4, since the exposed portion becomes Sn, the metal-containing resist film can be developed and a resist pattern can be formed by volatilizing the unexposed Sn(CH3)4.

[0035] [Etching Step] In this step, etching using the resist pattern as a mask is performed. The number of etching times can be once or multiple times, that is, sequential etching can be performed using the pattern obtained by etching as a mask. Examples of the etching method include dry etching and wet etching. By the above etching, a semiconductor substrate having a predetermined pattern is obtained.

[0036] As dry etching, for example, it can be carried out using a known dry etching apparatus. The etching gas used for dry etching can be appropriately selected according to the mask pattern, the elemental composition of the film to be etched, etc. For example, fluorine-based gases such as CHF3, CF4, C2F6, C3F8, SF6, etc., chlorine-based gases such as Cl2, BCl3, etc., oxygen-based gases such as O2, O3, H2O, etc., reducing gases such as H2, NH3, CO, CO2, CH4, C2H2, C2H4, C2H6, C3H4, C3H6, C3H8, HF, HI, HBr, HCl, NO, NH3, BCl3, etc., and inert gases such as He, N2, Ar, etc. These gases can also be used in combination.

[0037] 《Composition for Forming Resist Underlayer Film》 The composition for forming a resist underlayer film is used in a method for manufacturing a semiconductor substrate, which includes a step of coating the composition for forming a resist underlayer film directly or indirectly on a substrate, a step of forming a metal-containing resist film on the resist underlayer film formed by the above composition coating step for forming a resist underlayer film, a step of exposing the metal-containing resist film, and a step of forming a resist pattern by volatilizing a part of the exposed metal-containing resist film. The details of each step can preferably adopt the steps of the above method for manufacturing a semiconductor substrate. The composition for forming a resist underlayer film contains at least one selected from the group consisting of [A] an acid generating component, [B] an acid group-containing component, [C1] a photo base generator, and [C2] a base-containing component, and [E] a solvent.

[0038] ([A] Acid generating component) [A] The acid generating component includes a thermal acid generator (hereinafter, also referred to as [A1] thermal acid generator), a thermal acid generating polymer (hereinafter, also referred to as [A2] thermal acid generating polymer), and a photo acid generator (hereinafter, also referred to as [A3] photo acid generator). [A] The acid generating component can be used alone or in combination of two or more.

[0039] 〔[A1] Thermal acid generator〕 [A1] The thermal acid generator has a sulfo group, a carboxy group, a phosphono group, a phosphate group, a sulfate group, a sulfonamide group, a sulfonylimide group, -CRF1 R F2 OH (R F1 is a fluorine atom or a fluorinated alkyl group. R F2 is a hydrogen atom, a fluorine atom or a fluorinated alkyl group.) or a component of a low molecular weight compound generated by the action of heat having an acid group (hereinafter also referred to as "acid group (a)") which is a combination of these.

[0040] [A1] As the component generated from the thermal acid generator, sulfonic acid is preferred, fluorinated alkyl sulfonic acid having 1 to 10 carbon atoms and sulfonic acid having an alicyclic structure are more preferred, perfluoroalkyl sulfonic acid and 10-camphorsulfonic acid are even more preferred, and trifluoromethanesulfonic acid, nonafluorobutanesulfonic acid and 10-camphorsulfonic acid are particularly preferred.

[0041] [A1] Examples of the thermal acid generator include onium salt compounds such as iodonium salt compounds, organic sulfonic acid alkyl esters, 2,4,4,6-tetrabromocyclohexadienone, benzoin tosylate, 2-nitrobenzyl tosylate and the like.

[0042] Examples of the iodonium salt compound include salts of anions such as trifluoromethanesulfonate, nonafluoro-n-butanesulfonate, 10-camphorsulfonate, pyrenesulfonate, n-dodecylbenzenesulfonate, naphthalenesulfonate and the like with iodonium cations such as diphenyliodonium, bis(4-t-butylphenyl)iodonium and the like.

[0043] [A1] As the thermal acid generator, onium salt compounds are preferred, iodonium salt compounds are more preferred, and bis(4-t-butylphenyl)iodonium trifluoromethanesulfonate, bis(4-t-butylphenyl)iodonium nonafluoro-n-butanesulfonate and bis(4-t-butylphenyl)iodonium 10-camphorsulfonate are even more preferred.

[0044] When the composition for forming a resist lower layer film contains a [A1] thermal acid generator, the lower limit of the content ratio of the [A1] thermal acid generator in the components other than the solvent in the lower layer film forming composition is preferably 0.1% by mass, more preferably 1% by mass, and still more preferably 2% by mass. Further, as the upper limit of the above content ratio, 20% by mass is preferable, 15% by mass is more preferable, 12% by mass is still more preferable, and 10% by mass is particularly preferable.

[0045] 〔[A2] Thermal acid generating polymer〕 [A2] The thermal acid generating polymer is an organic polymer that generates a component having an acid group (a) by the action of heat. The component generated from the [A2] thermal acid generating polymer may be a low molecular compound having an acid group (a) or an organic polymer having an acid group (a), but an organic polymer having an acid group (a) is preferable.

[0046] The lower limit of the Mw of the [A2] thermal acid generating polymer is preferably 1,600, more preferably 2,000, and still more preferably 2,500. The upper limit of the above Mw is preferably 50,000, more preferably 30,000, and still more preferably 15,000.

[0047] Examples of the [A2] thermal acid generating polymer include polymers having a structural unit in which one or more [A1] thermal acid generators are incorporated, and a structural unit having an alkoxysulfonyl group is preferable. Examples of the alkoxysulfonyl group include an alkoxysulfonyl group having 1 to 20 carbon atoms, and an ethoxysulfonyl group is preferable. As the structural unit containing an alkoxysulfonyl group, a styrene-based structural unit containing an aromatic ring substituted with an alkoxysulfonyl group is preferable, and a structural unit represented by the following formula is more preferable. Note that the [A2] thermal acid generating polymer may have other structural units other than the structural unit in which the [A1] thermal acid generator is incorporated.

[0048]

Chemical formula

[0049] In the above formula, R 1is a hydrogen atom, a fluorine atom, a methyl group or a trifluoromethyl group. A is a single bond, an alkylene group having 1 to 10 carbon atoms, a cycloalkylene group having 4 to 20 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a divalent hydrocarbon group composed of a combination thereof. R 2 is an alkyl group having 1 to 20 carbon atoms.

[0050] [A2] As the lower limit of the content ratio of the structural unit in which the [A1] thermal acid generator is incorporated in all the structural units constituting the thermal acid generating polymer, 1 mol% is preferable, and 5 mol% is more preferable. As the upper limit of the content ratio of the above structural unit, 80 mol% is preferable, and 60 mol% is more preferable.

[0051] [A2] The thermal acid generating polymer may have other structural units other than the structural unit in which the [A1] thermal acid generator is incorporated. The above structural unit is not particularly limited, and examples thereof include the same as the structural units constituting each resin in the [D1] organic polymer described later.

[0052] [A2] As the lower limit of the content ratio of the above other structural units in all the structural units constituting the thermal acid generating polymer, 5 mol% is preferable, and 10 mol% is more preferable. As the upper limit of the content ratio of the above structural unit, 80 mol% is preferable, and 50 mol% is more preferable.

[0053] When the resist underlayer film forming composition contains the [A2] thermal acid generating polymer, as the lower limit of the content ratio of the [A2] thermal acid generating polymer in the components other than the solvent in the underlayer film forming composition, 80% by mass is preferable, 90% by mass is more preferable, and 95% by mass is even more preferable. Also, the upper limit of the above content ratio may be 100% by mass.

[0054] ([A3] Photoacid generator) [A3] The photoacid generator is a component that generates an acid by the action of radiation. The [A3] photoacid generator can be used alone or in combination of two or more.

[0055] [A3] As the acid generated from the photoacid generator, sulfonic acid is preferred, more preferably fluorinated alkyl sulfonic acid having 1 to 10 carbon atoms and sulfonic acid having an alicyclic structure, still more preferably perfluoroalkyl sulfonic acid and 10-camphorsulfonic acid, and particularly preferably trifluoromethanesulfonic acid, nonafluorobutanesulfonic acid and 10-camphorsulfonic acid.

[0056] [A3] Examples of the photoacid generator include onium salt compounds, N-sulfonyloxyimide compounds, halogen-containing compounds, diazoketone compounds and the like.

[0057] Examples of the onium salt compound include sulfonium salts, tetrahydrothiophenium salts, iodonium salts, phosphonium salts, diazonium salts, pyridinium salts and the like.

[0058] Examples of the anion of the onium salt compound include anions represented by the following formula and the like.

[0059]

Chemical formula

[0060] Examples of the cation of the onium salt compound include cations represented by the following formula and the like.

[0061]

Chemical formula

[0062] As the onium salt compound, those obtained by appropriately combining the above anion and the above cation can be used.

[0063] Examples of the N-sulfonyloxyimide compound include compounds represented by the following formula and the like.

[0064]

Chemical formula

[0065] [A3] As the photoacid generator, an onium salt compound is preferable, a sulfonium salt is more preferable, and triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluorobutanesulfonate, and triphenylsulfonium camphorsulfonate are even more preferable.

[0066] When the composition for forming the resist underlayer film contains the [A3] photoacid generator, the lower limit of the content ratio of the [A3] photoacid generator in the components other than the solvent in the underlayer film-forming composition is preferably 0.1% by mass, more preferably 1% by mass, and even more preferably 2% by mass. Further, the upper limit of the above content ratio is preferably 20% by mass, more preferably 15% by mass, even more preferably 12% by mass, and particularly preferably 10% by mass.

[0067] ([B] Acid group-containing component) [B] The acid group-containing component is a component other than the [A] acid-generating component and has an acid group (a). The [B] acid group-containing component may be a low molecular compound (hereinafter also referred to as [B1] acid group-containing compound) or an organic polymer (hereinafter also referred to as [B2] acid group-containing polymer). The [B] acid group-containing component can be used alone or in combination of two or more.

[0068] [[B1] Acid group-containing compound] [B1] The acid group-containing compound is a low molecular compound having an acid group (a). Specific examples of the [B1] acid group-containing compound include those similar to the components having the acid group (a) generated from the above-mentioned [A1] thermal acid generator.

[0069] When the composition for forming a resist underlayer film contains a [B1] acid group-containing compound, the lower limit of the content ratio of the [B1] acid group-containing compound in the components other than the solvent in the underlayer film-forming composition is preferably 0.1% by mass, more preferably 1% by mass, and still more preferably 2% by mass. Further, the upper limit of the above content ratio is preferably 20% by mass, more preferably 15% by mass, still more preferably 10% by mass, and particularly preferably 8% by mass.

[0070] [[B2] Acid group-containing polymer] [[B2] Acid group-containing polymer is an organic polymer having an acid group (a). Examples of the [B2] acid group-containing polymer include ion exchange resins having a structural unit containing the acid group (a).

[0071] The lower limit of the Mw of the [B2] acid group-containing polymer is preferably 1,600, more preferably 2,000, and still more preferably 2,500. On the other hand, the upper limit of the above Mw is preferably 50,000, more preferably 30,000, and still more preferably 15,000.

[0072] Examples of the ion exchange resin include polymers obtained by introducing the acid group (a) into organic polymers such as styrene-based polymers, (meth)acrylic-based polymers, polyester-based polymers, cellulose, and polytetrafluoroethylene. More specifically, polymers obtained by sulfonating novolak resins, polymers obtained by sulfonating resol resins, polymers obtained by sulfonating styrene-based polymers crosslinked with divinylbenzene, polymers obtained by carboxylating (meth)acrylic-based polymers crosslinked with divinylbenzene, and the like can be mentioned. Examples of the novolak resin and resol resin sulfonated in the ion exchange resin include those similar to the novolak resin and resol resin in the [D1] organic polymer described later.

[0073] As the structural unit containing the acid group (a), those obtained by introducing a sulfonic group into the structural unit of a novolak resin are preferable. Examples of such a structural unit include structural units represented by the following formula.

[0074] [Chemical formula]

[0075] [B2] As the lower limit of the content ratio of the structural unit containing the acid group (a) in all the structural units constituting the acid group-containing polymer, 5 mol% is preferable, and 10 mol% is more preferable. On the other hand, as the upper limit of the content ratio of the above structural unit, 80 mol% is preferable, and 50 mol% is more preferable.

[0076] [B2] As the lower limit of the content ratio of the structural unit not containing the acid group (a) in all the structural units constituting the acid group-containing polymer, 5 mol% is preferable, and 10 mol% is more preferable. On the other hand, as the upper limit of the content ratio of the above structural unit, 80 mol% is preferable, and 50 mol% is more preferable.

[0077] When the composition for forming a resist lower layer film contains a [B2] acid group-containing polymer, as the lower limit of the content ratio of the [B2] acid group-containing polymer in the components other than the solvent in the composition for forming a lower layer film, 80% by mass is preferable, 90% by mass is more preferable, and 95% by mass is even more preferable. Also, the upper limit of the above content ratio may be 100% by mass.

[0078] ([C1] Photo-base generator) [C1] A photo-base generator is a component that generates a base by the action of radiation. Examples of the base generated from the [C] photo-base generator include amines such as primary amines, secondary amines, and tertiary amines. The [C1] photo-base generator can be used alone or in combination of two or more.

[0079] Examples of the [C1] photo-base generator include transition metal complexes such as cobalt, ortho-nitrobenzyl carbamates, α,α-dimethyl-3,5-dimethoxybenzyl carbamates, acyloxyimino compounds, acetophenone-based compounds, and the like.

[0080] Examples of the cobalt transition metal complex include compounds described in paragraph

[0198] of JP-A-2017-009673 and the like.

[0081] Examples of the ortho-nitrobenzyl carbamates include [[(2-nitrobenzyl)oxy]carbonyl]methylamine, [[(2-nitrobenzyl)oxy]carbonyl]propylamine, [[(2-nitrobenzyl)oxy]carbonyl]hexylamine, [[(2-nitrobenzyl)oxy]carbonyl]cyclohexylamine, [[(2-nitrobenzyl)oxy]carbonyl]aniline, [[(2-nitrobenzyl)oxy]carbonyl]piperidine, bis[[(2-nitrobenzyl)oxy]carbonyl]hexamethylenediamine, bis[[(2-nitrobenzyl)oxy]carbonyl]phenylenediamine, bis[[(2-nitrobenzyl)oxy]carbonyl]toluenediamine, bis[[(2-nitrobenzyl)oxy]carbonyl]diaminodiphenylmethane, bis[[(2-nitrobenzyl)oxy]carbonyl]piperazine, [[(2,6-dinitrobenzyl)oxy]carbonyl]methylamine, [[(2,6-dinitrobenzyl)oxy]carbonyl]propylamine, [[(2,6-dinitrobenzyl)oxy]carbonyl]hexylamine, [[(2,6-dinitrobenzyl)oxy]carbonyl]cyclohexylamine, [[(2,6-dinitrobenzyl)oxy]carbonyl]aniline, [[(2,6-dinitrobenzyl)oxy]carbonyl]piperidine, bis[[(2,6-dinitrobenzyl)oxy]carbonyl]hexamethylenediamine, bis[[(2,6-dinitrobenzyl)oxy]carbonyl]phenylenediamine, bis[[(2,6-dinitrobenzyl)oxy]carbonyl]toluenediamine, bis[[(2,6-dinitrobenzyl)oxy]carbonyl]diaminodiphenylmethane, bis[[(2,6-dinitrobenzyl)oxy]carbonyl]piperazine, and the like.

[0082] Examples of α,α-dimethyl-3,5-dimethoxybenzyl carbamates include [[(α,α-dimethyl-3,5-dimethoxybenzyl)oxy]carbonyl]methylamine, [[(α,α-dimethyl-3,5-dimethoxybenzyl)oxy]carbonyl]propylamine, [[(α,α-dimethyl-3,5-dimethoxybenzyl)oxy]carbonyl]hexylamine, [[(α,α-dimethyl-3,5-dimethoxybenzyl)oxy]carbonyl]cyclohexylamine, [[(α,α-dimethyl-3,5-dimethoxybenzyl)oxy]carbonyl]aniline, [[(α,α-dimethyl-3,5-dimethoxybenzyl)oxy]carbonyl]piperidine, bis[[(α,α-dimethyl-3,5-dimethoxybenzyl)oxy]carbonyl]hexamethylenediamine, bis[[(α,α-dimethyl-3,5-dimethoxybenzyl)oxy]carbonyl]phenylenediamine, bis[[(α,α-dimethyl-3,5-dimethoxybenzyl)oxy]carbonyl]toluenediamine, bis[[(α,α-dimethyl-3,5-dimethoxybenzyl)oxy]carbonyl]diaminodiphenylmethane, bis[[(α,α-dimethyl-3,5-dimethoxybenzyl)oxy]carbonyl]piperazine, and the like.

[0083] Examples of acyloxyimines include propionylacetophenone oxime, propionylbenzophenone oxime, propionylacetone oxime, butyrylacetophenone oxime, butyrylbenzophenone oxime, butyrylacetone oxime, adipoylacetophenone oxime, adipoylbenzophenone oxime, adipoylacetone oxime, acryloylacetophenone oxime, acryloylbenzophenone oxime, acryloylacetone oxime, and the like.

[0084] Examples of acetophenone compounds include acetophenone compounds having an α-aminoketone structure such as 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one, 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, and the like.

[0085] Examples of the photo-base generator include, in addition to the above-described compound examples, 2-nitrobenzyl cyclohexylcarbamate, O-carbamoylhydroxyamide, and O-carbamoylhydroxyamide.

[0086] As the photo-base generator, acetophenone compounds and 2-nitrobenzyl cyclohexylcarbamate are preferred, acetophenone compounds having an α-aminoketone structure and 2-nitrobenzyl cyclohexylcarbamate are more preferred, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one are even more preferred.

[0087] ([C2]Base-containing component) Examples of the base-containing component include onium salt compounds that do not decompose by the action of heat, such as sulfonium salt compounds, and amines.

[0088] Examples of the sulfonium salt compound include compounds represented by the following formula.

[0089]

Chemical formula

[0090] Examples of the amines include aliphatic amines, aromatic amines, heterocyclic amines, quaternary ammonium hydroxides, carboxylic acid quaternary ammonium salts, and the like.

[0091] Examples of the aliphatic amine include aliphatic amines such as trimethylamine, diethylamine, triethylamine, di-n-propylamine, tri-n-propylamine, di-n-pentylamine, tri-n-pentylamine, diethanolamine, triethanolamine, dicyclohexylamine, dicyclohexylmethylamine, and the like.

[0092] Examples of the aromatic amine include aniline, benzylamine, N,N-dimethylaniline, diphenylamine, and the like.

[0093] Examples of the heterocyclic amine include pyridine, 2-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 4-ethylpyridine, 2-phenylpyridine, 4-phenylpyridine, N-methyl-4-phenylpyridine, 4-dimethylaminopyridine, imidazole, benzimidazole, 4-methylimidazole, 2-phenylbenzimidazole, 2,4,5-triphenylimidazole, nicotine, nicotinic acid, nicotinamide, quinoline, 8-hydroxyquinoline, pyrazine, pyrazole, pyridazine, purine, pyrrolidine, piperidine, piperazine, morpholine, 4-methylmorpholine, 1,5-diazabicyclo[4,3,0]-5-nonene, 1,8-diazabicyclo[5,3,0]-7-undecene, and the like.

[0094] Examples of the quaternary ammonium hydroxide include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetra-n-butylammonium hydroxide, tetra-n-hexylammonium hydroxide, and the like.

[0095] Examples of the quaternary ammonium carboxylate salt include tetramethylammonium acetate, tetramethylammonium benzoate, tetra-n-butylammonium acetate, tetra-n-butylammonium benzoate, and the like.

[0096] When the composition for forming a resist underlayer film contains a [C1] photo-base generator or a [C2] base-containing component, the lower limit of the content ratio of the [C1] photo-base generator or the [C2] base-containing component in the components other than the solvent in the underlayer film-forming composition is preferably 0.1% by mass, more preferably 1% by mass, and even more preferably 2% by mass. Further, as the upper limit of the above content ratio, 20% by mass is preferable, 15% by mass is more preferable, 10% by mass is even more preferable, and 8% by mass is particularly preferable.

[0097] The composition for forming a resist underlayer film may further contain an organic polymer other than the [B] acid group-containing component (hereinafter also referred to as "[D1] organic polymer"), [D2] inorganic polymer, [D3] aromatic ring-containing compound, [D4] additive, and the like.

[0098] ([D1] organic polymer) As the [D1] organic polymer, for example, those described in paragraphs

[0040] to

[0116] of JP-A-2016-206676 can be used. From the viewpoint of further improving the etching resistance of the underlayer film, novolak resins, resol resins, aromatic ring-containing vinyl resins, acenaphthylene resins, indene resins, polyarylene resins, triazine resins, calixarene resins, fullerene resins, and pyrene resins are preferable, and novolak resins and acenaphthylene resins are more preferable.

[0099] The lower limit of the Mw of the novolak resin, resol resin, aromatic ring-containing vinyl resin, acenaphthylene resin, indene resin, polyarylene resin, triazine resin, fullerene resin, or pyrene resin is preferably 500, more preferably 1,000, and even more preferably 2,000. On the other hand, the upper limit of the Mw is preferably 10,000. Further, the lower limit of the ratio of Mw to Mn (Mw / Mn) of these resins is preferably 1.1. On the other hand, the upper limit of the Mw / Mn is preferably 5, more preferably 3, and even more preferably 2. By setting the Mw and Mw / Mn within the above ranges, the flatness and surface coatability of the underlayer film can be improved.

[0100] From the viewpoint of improving the flatness of the resist underlayer film, the lower limit of the molecular weight of the calixarene-based resin is preferably 500, more preferably 700, and even more preferably 1,000. As the upper limit of the molecular weight, 5,000 is preferable, 3,000 is more preferable, and 1,500 is even more preferable. When the calixarene-based resin has a molecular weight distribution, the molecular weight of the calixarene-based resin means Mw in terms of polystyrene by GPC.

[0101] ([D2] Inorganic polymer) Examples of the [D2] inorganic polymer include [D2-1] polysiloxane, [D2-2] a complex (polynuclear complex) containing a plurality of metal atoms, oxygen atoms (hereinafter also referred to as "crosslinking oxygen atoms") that crosslink between these metal atoms, and a polydentate ligand coordinated to the above metal atoms, and [D2-3] polycarbosilane and the like.

[0102] 〔[D2-1] Polysiloxane〕 Examples of the [D2-1] polysiloxane include those having a structural unit (I) represented by the following formula (I) and / or a structural unit (II) represented by the following formula (II). Each structural unit in the [D2-1] polysiloxane can be used alone or in combination of two or more.

[0103]

Chemical formula

[0104] In the above formula (I), R X1 is a monovalent organic group having 1 to 20 carbon atoms.

[0105] Here, the "organic group" means a group having at least one carbon atom.

[0106] R X1As the monovalent organic group represented by , a monovalent hydrocarbon group, a monovalent fluorinated hydrocarbon group, or a monovalent group (α) having a divalent heteroatom-containing group between carbon-carbon atoms of a monovalent hydrocarbon group is preferable, a monovalent chain hydrocarbon group, a monovalent aromatic hydrocarbon group, a monovalent fluorinated aromatic hydrocarbon group, or a group containing a heterocyclic ring is more preferable, and an alkyl group, an aryl group, a fluoroaryl group, or a group containing a nitrogen-containing heterocyclic ring is more preferable. Examples of the nitrogen-containing heterocyclic ring include an azocycloalkane ring, an isocyanuric ring, and the like.

[0107] Examples of the structural unit (I) include structural units represented by the following formulas and the like.

[0108] [Chemical formula]

[0109] [D2-1] As the lower limit of the content ratio of the structural unit (I) in the polysiloxane, 1 mol% is preferable, and 5 mol% is more preferable. On the other hand, as the upper limit of the content ratio of the structural unit (I), 60 mol% is preferable, and 40 mol% is more preferable.

[0110] [D2-1] As the lower limit of the content ratio of the structural unit (II) in the polysiloxane, 40 mol% is preferable, and 60 mol% is more preferable. On the other hand, as the upper limit of the content ratio of the structural unit (II), 99 mol% is preferable, and 95 mol% is more preferable.

[0111] [D2-1] As the lower limit of Mw of the polysiloxane, 500 is preferable, 800 is more preferable, and 1,200 is further preferable. On the other hand, as the upper limit of the above Mw, 100,000 is preferable, 30,000 is more preferable, 10,000 is further preferable, and 5,000 is particularly preferable.

[0112] [Complex [D2-2]] [D2-2] As the metal atoms in the complex, titanium, tantalum, zirconium, and tungsten (hereinafter also referred to as "specific metal atoms") are preferred, and titanium and zirconium are more preferred. These metal atoms can be used alone or in combination of two or more.

[0113] [D2-2] By containing a bridging oxygen atom, the complex can become a stable polynuclear complex. A plurality of bridging oxygen atoms may be bonded to one metal atom, but for some metal atoms, only one bridging oxygen atom may be bonded to one metal atom. [C2-2] The complex preferably mainly contains a structure in which two bridging oxygen atoms are bonded to one metal atom. Here, "mainly containing" the above structure means that for 50 mol% or more, preferably 70 mol% or more, more preferably 90 mol% or more, and particularly preferably 95 mol% or more of the total metal atoms constituting the [D2-2] complex, two bridging oxygen atoms are bonded to each metal atom.

[0114] [D2-2] In addition to the bridging oxygen atom, the complex may have other bridging ligands such as a peroxide ligand (-O-O-).

[0115] [D2-2] The polydentate ligand in the complex improves the solubility of the [C2-2] complex, thereby improving the removability of the underlying film. As the polydentate ligand, a hydroxy acid ester, β-diketone, β-ketoester, malonic acid diester (hereinafter also referred to as "malonic acid diesters") in which the carbon atom at the α-position may be substituted, a hydrocarbon having a π bond, or a ligand derived from these compounds is preferred. These compounds usually form a polydentate ligand as an anion obtained by gaining one electron, as an anion from which a proton has been eliminated, or form a polydentate ligand in their original structure.

[0116] [D2-2] As the lower limit of the molar ratio of the polydentate ligand to the metal atom (polydentate ligand / metal atom) in the complex, 1 is preferable, 1.5 is more preferable, and 1.8 is even more preferable. On the other hand, as the upper limit of the above ratio, 3 is preferable, 2.5 is more preferable, and 2.2 is even more preferable.

[0117] [D2-2] The complex may contain other ligands in addition to the above-mentioned bridging ligand and polydentate ligand.

[0118] [[D2-3] Polycarbosilane] [D2-3] Polycarbosilane is a polymer having a Si-C bond in the main chain.

[0119] [D2-3] Polycarbosilane has, for example, a first structural unit represented by the following formula (i) (hereinafter also referred to as "structural unit (i)"). Further, [D2-3] polycarbosilane may have a second structural unit represented by formula (ii) (hereinafter also referred to as "structural unit (ii)") and a third structural unit represented by formula (iii) (hereinafter also referred to as "structural unit (iii)") described later. [D2-3] Polycarbosilane can be used alone or in combination of two or more.

[0120] (Structural unit (i)) The structural unit (i) is represented by the following formula (i).

[0121] [Chemical formula]

[0122] In the above formula (i), R 1 is a divalent hydrocarbon group having 1 to 20 carbon atoms which may be substituted or unsubstituted. X and Y are each independently a hydrogen atom, a hydroxy group, a halogen atom or a monovalent organic group having 1 to 20 carbon atoms.

[0123] R in the above formula (i) 1Examples thereof include a substituted or unsubstituted divalent linear hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 20 carbon atoms, and the like. In the present specification, the linear hydrocarbon group includes both a linear hydrocarbon group and a branched-chain hydrocarbon group.

[0124] Examples of the above unsubstituted divalent linear hydrocarbon group having 1 to 20 carbon atoms include linear saturated hydrocarbon groups such as a methanediyl group and an ethanediyl group, and linear unsaturated hydrocarbon groups such as an ethenediyl group and a propenediyl group.

[0125] Examples of the above unsubstituted divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include monocyclic alicyclic saturated hydrocarbon groups such as a cyclobutanediyl group, monocyclic alicyclic unsaturated hydrocarbon groups such as a cyclobutenediyl group, polycyclic alicyclic saturated hydrocarbon groups such as a bicyclo[2.2.1]heptanediyl group, and polycyclic alicyclic unsaturated hydrocarbon groups such as a bicyclo[2.2.1]heptenediyl group.

[0126] Examples of the above unsubstituted divalent aromatic hydrocarbon group having 6 to 20 carbon atoms include a phenylene group, a biphenylene group, a phenyleneethylene group, a naphthylene group, and the like.

[0127] Examples of the substituent in the above substituted divalent hydrocarbon group having 1 to 20 carbon atoms represented by R 1 include a halogen atom, a hydroxy group, a cyano group, a nitro group, an alkoxy group, an acyl group, an acyloxy group, and the like.

[0128] R 1 is preferably an unsubstituted linear saturated hydrocarbon group, more preferably a methanediyl group or an ethanediyl group.

[0129] Examples of the monovalent organic group having 1 to 20 carbon atoms represented by X or Y in the above formula (i) include a monovalent hydrocarbon group having 1 to 20 carbon atoms, a monovalent group having a divalent heteroatom-containing group between carbon-carbon atoms of this hydrocarbon group, a monovalent group in which part or all of the hydrogen atoms of the above hydrocarbon group or the group containing the above divalent heteroatom-containing group are substituted with a monovalent heteroatom-containing group, and the like.

[0130] Examples of the monovalent hydrocarbon group having 1 to 20 carbon atoms include a monovalent linear hydrocarbon group having 1 to 20 carbon atoms, a monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, a monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms, and the like.

[0131] Examples of the monovalent linear hydrocarbon group having 1 to 20 carbon atoms include an alkyl group such as a methyl group or an ethyl group, an alkenyl group such as an ethenyl group, and an alkynyl group such as an ethynyl group.

[0132] Examples of the monovalent alicyclic hydrocarbon group having 3 to 20 carbon atoms include a monovalent monocyclic alicyclic saturated hydrocarbon group such as a cyclopentyl group or a cyclohexyl group, a monovalent monocyclic alicyclic unsaturated hydrocarbon group such as a cyclopentenyl group or a cyclohexenyl group, a monovalent polycyclic alicyclic saturated hydrocarbon group such as a norbornyl group or an adamantyl group, and a monovalent polycyclic alicyclic unsaturated hydrocarbon group such as a norbornenyl group or a tricyclodecenyl group.

[0133] Examples of the monovalent aromatic hydrocarbon group having 6 to 20 carbon atoms include an aryl group such as a phenyl group, a tolyl group, a xylyl group, a naphthyl group, a methylnaphthyl group, or an anthryl group, and an aralkyl group such as a benzyl group, a naphthylmethyl group, or an anthrylmethyl group.

[0134] Examples of the heteroatom constituting the divalent or monovalent heteroatom-containing group include an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom, a silicon atom, a halogen atom, and the like. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like.

[0135] Examples of the divalent heteroatom-containing group include -O-, -CO-, -S-, -CS-, -NR'-, and groups formed by combining two or more of these, where R' is a hydrogen atom or a monovalent hydrocarbon group.

[0136] Examples of the monovalent heteroatom-containing group include halogen atoms such as fluorine atom, chlorine atom, bromine atom, and iodine atom, hydroxy group, carboxy group, cyano group, amino group, and sulfanyl group.

[0137] The monovalent organic group having 1 to 20 carbon atoms represented by X or Y is preferably a monovalent hydrocarbon group, more preferably a monovalent chain hydrocarbon group or a monovalent aromatic hydrocarbon group, and still more preferably an alkyl group or an aryl group.

[0138] The number of carbon atoms of the monovalent organic group represented by X or Y is preferably 1 to 10, and more preferably 1 to 6.

[0139] Examples of the halogen atom represented by X or Y include fluorine atom, chlorine atom, bromine atom, and iodine atom. As this halogen atom, a chlorine atom or a bromine atom is preferable.

[0140] When the polycarbosilane [D2-3] has the structural unit (i), the lower limit of the content ratio of the structural unit (i) to all the structural units constituting the polycarbosilane [D2-3] is preferably 5 mol%, more preferably 30 mol%, still more preferably 60 mol%, and particularly preferably 80 mol%. The upper limit of the content ratio of the structural unit (i) may be 100 mol%. By setting the content ratio of the structural unit (i) within the above range, the removability of the silicon-containing film (I) by the removing liquid (I) in the method for treating the semiconductor substrate can be further improved. The content ratio (mol%) of each structural unit of the polycarbosilane [D2-3] usually becomes equivalent to the molar ratio of the monomer that gives each structural unit used in the synthesis of the polycarbosilane [D2-3].

[0141] (Structural unit (ii)) The structural unit (ii) is an optional structural unit that the [D2-3] polycarbosilane may have, and is represented by the following formula (ii).

[0142] [Chemical formula]

[0143] When the [D2-3] polycarbosilane has the structural unit (ii), the lower limit of the content ratio of the structural unit (ii) to all the structural units constituting the [D2-3] polycarbosilane is preferably 0.1 mol%, more preferably 1 mol%, and even more preferably 5 mol%. On the other hand, the upper limit of the content ratio of the structural unit (ii) is preferably 50 mol%, more preferably 40 mol%, even more preferably 30 mol%, and particularly preferably 20 mol%.

[0144] (Structural unit (iii)) The structural unit (iii) is an optional structural unit that the [D2-3] polycarbosilane may have, and is represented by the following formula (iii).

[0145] [Chemical formula]

[0146] In the above formula (iii), R 2 is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms. c is 1 or 2. When c is 2, the two R 2 are the same as or different from each other.

[0147] As the above c, 1 is preferred.

[0148] R 2 Examples of R include the same groups as the monovalent hydrocarbon groups having 1 to 20 carbon atoms exemplified for X and Y in the above formula (i). Further, examples of the substituents of the monovalent hydrocarbon groups having 1 to 20 carbon atoms include the same groups as the monovalent heteroatom-containing groups exemplified for X and Y in the above formula (i).

[0149] R 2 is preferably a substituted or unsubstituted monovalent linear hydrocarbon group or a substituted or unsubstituted monovalent aromatic hydrocarbon group, more preferably an alkyl group or an aryl group, and even more preferably a methyl group or a phenyl group.

[0150] When the polycarbosilane [D2-3] has the structural unit (iii), the lower limit of the content ratio of the structural unit (iii) to all the structural units constituting the polycarbosilane [D2-3] is preferably 0.1 mol%, more preferably 1 mol%, and even more preferably 5 mol%. The upper limit of the content ratio of the structural unit (iii) is preferably 50 mol%, more preferably 40 mol%, even more preferably 30 mol%, and particularly preferably 20 mol%.

[0151] ([D3] Aromatic ring-containing compound) [D3] The aromatic ring-containing compound is a compound having an aromatic ring and a molecular weight of 600 or more and 3,000 or less (however, excluding [D1] organic polymers and [D2] inorganic polymers). When the [D3] aromatic ring-containing compound has a molecular weight distribution, the molecular weight of the [D3] aromatic ring-containing compound means, for example, the weight average molecular weight (Mw) in terms of polystyrene by GPC. By containing the [D3] aromatic ring-containing compound in the resist underlayer film-forming composition, the heat resistance and etching resistance of the underlayer film can be improved in the same manner as in the case of containing the [D1] organic polymer having an aromatic ring. Specific examples of the [D3] aromatic ring-containing compound include, for example, the compounds described in paragraphs

[0117] to

[0179] of JP-A-2016-206676.

[0152] ([D4] Additive) [Examples of the [D4] additive include [D4-1] crosslinking agents, [D4-2] crosslinking accelerators, surfactants, etc. The resist underlayer film-forming composition preferably further contains a [D4-1] crosslinking agent and / or a [D4-2] crosslinking accelerator.

[0153] [[D4-1] Crosslinking agent] [D4-1] The crosslinking agent is a component that forms a crosslinking bond between organic polymers or the like by the action of heat or the like. By containing the [D4-1] crosslinking agent in the composition for forming the resist underlayer film, the hardness of the underlayer film can be improved.

[0154] Examples of the [D4-1] crosslinking agent include compounds having an alkoxylated amino group, hydroxymethyl group-substituted phenol compounds, and the like.

[0155] Examples of the hydroxymethyl group-substituted phenol compound include 2-hydroxymethyl-4,6-dimethylphenol, 1,3,5-trihydroxymethylbenzene, 3,5-dihydroxymethyl-4-methoxytoluene [2,6-bis(hydroxymethyl)-p-cresol], 4,4'-(1-(4-(1-(4-hydroxy-3,5-bis(methoxymethyl)phenyl)-1-methylethyl)phenyl)ethylidene)bis(2,6-bis(methoxymethyl)phenol), 5,5'-(1-methylethylidene)bis(2-hydroxy-1,3-benzenedimethanol), and the like.

[0156] Examples of the compound having an alkoxylated amino group include compounds in which at least a part of the hydrogen atoms of the hydroxy groups in the methylol groups of nitrogen-containing compounds having a plurality of active methylol groups in one molecule, such as (poly)methylolated melamine, (poly)methylolated glycoluril, (poly)methylolated benzoguanamine, (poly)methylolated urea, are substituted with alkyl groups such as methyl groups and butyl groups. The compound having an alkoxylated amino group may be a mixture of a plurality of substituted compounds, or may contain an oligomer component formed by partial self-condensation.

[0157] [D4-1] As crosslinking agents, in addition to the compounds described above, for example, polyfunctional (meth)acrylate compounds, epoxy compounds, hydroxymethyl group-substituted phenol compounds, alkoxyalkyl group-containing phenol compounds, etc. can also be used. Specific examples of these compounds include, for example, the compounds described in paragraphs

[0203] to

[0207] of JP-A-2016-206676.

[0158] [D4-1] As crosslinking agents, hydroxymethyl group-substituted phenol compounds and compounds having an alkoxylated amino group are preferred, and 5,5'-(1-methylethylidene)bis(2-hydroxy-1,3-benzenedimethanol) and 2,4,6-tris[bis(methoxymethyl)amino]-1,3,5-triazine are more preferred.

[0159] When the composition for forming a resist underlayer film contains a [D4-1] crosslinking agent, the lower limit of the content ratio of the [D4-1] crosslinking agent in the components other than the solvent in the underlayer film-forming composition is preferably 0.1% by mass, more preferably 1% by mass, and even more preferably 2% by mass. Further, the upper limit of the above content ratio is preferably 20% by mass, more preferably 15% by mass, even more preferably 10% by mass, and particularly preferably 8% by mass.

[0160] 〔[D4-2] Crosslinking accelerator〕 [D4-2] Crosslinking accelerators promote the formation of crosslinking bonds by [D4-1] crosslinking agents and hydrolysis condensation by hydrolyzable groups remaining in [D2-1] polysiloxanes, [D2-2] complexes, etc. As [D4-2] crosslinking accelerators, for example, nitrogen-containing compounds having acid dissociable groups can be used.

[0161] Examples of the nitrogen-containing compound having an acid-dissociable group include N-t-butoxycarbonylpiperidine, N-t-butoxycarbonylimidazole, N-t-butoxycarbonylbenzimidazole, N-t-butoxycarbonyl-2-phenylbenzimidazole, N-(t-butoxycarbonyl)di-n-octylamine, N-(t-butoxycarbonyl)diethanolamine, N-(t-butoxycarbonyl)dicyclohexylamine, N-(t-butoxycarbonyl)diphenylamine, N-t-butoxycarbonyl-4-hydroxypiperidine, N-t-amyloxycarbonyl-4-hydroxypiperidine, and the like.

[0162] When the composition for forming a resist underlayer film contains a [D4-2] crosslinking accelerator, the lower limit of the content ratio of the [D4-2] crosslinking accelerator in the components other than the solvent in the composition for forming a lower layer film is preferably 0.1% by mass, more preferably 1% by mass, still more preferably 2% by mass. Further, the upper limit of the above content ratio is preferably 20% by mass, more preferably 15% by mass, still more preferably 10% by mass, and particularly preferably 8% by mass.

[0163] The surfactant improves the coating surface uniformity of the formed underlayer film and suppresses the occurrence of coating spots. As specific examples of the surfactant, those described in paragraph

[0216] of JP-A-2016-206676 and the like can be used.

[0164] ([E] Solvent) Examples of the [E] solvent include hydrocarbon solvents, ester solvents, alcohol solvents, ketone solvents, ether solvents, nitrogen-containing solvents, and the like. The [E] solvent can be used alone or in combination of two or more.

[0165] Examples of the hydrocarbon solvent include aliphatic hydrocarbon solvents such as n-pentane, n-hexane, and cyclohexane, and aromatic hydrocarbon solvents such as benzene, toluene, and xylene.

[0166] Examples of ester solvents include carbonate solvents such as diethyl carbonate, monoester solvents such as methyl acetate and ethyl acetate, lactone solvents such as γ-butyrolactone, polyhydric alcohol partial ether carboxylate solvents such as diethylene glycol monomethyl ether acetate and propylene glycol monomethyl ether acetate, and lactate solvents such as methyl lactate and ethyl lactate.

[0167] Examples of alcohol solvents include monoalcohol solvents such as methanol, ethanol, n-propanol, and 4-methyl-2-pentanol, and polyhydric alcohol solvents such as ethylene glycol and 1,2-propylene glycol.

[0168] Examples of ketone solvents include chain ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, and cyclic ketone solvents such as cyclohexanone.

[0169] Examples of ether solvents include chain ether solvents such as n-butyl ether, cyclic ether solvents such as tetrahydrofuran, polyhydric alcohol ether solvents, and polyhydric alcohol partial ether solvents such as diethylene glycol monomethyl ether and propylene glycol monomethyl ether.

[0170] Examples of nitrogen-containing solvents include chain nitrogen-containing solvents such as N,N-dimethylacetamide, and cyclic nitrogen-containing solvents such as N-methylpyrrolidone.

[0171] [E] As the solvent, an alcohol solvent, an ether solvent or an ester solvent is preferred, a monoalcohol solvent, a polyhydric alcohol partial ether solvent or a polyhydric alcohol partial ether carboxylate solvent is more preferred, and 4-methyl-2-pentanol, propylene glycol monomethyl ether or propylene glycol monomethyl ether acetate is even more preferred.

[0172] As the lower limit of the content ratio of the [E] solvent in the composition for forming a resist underlayer film, 50% by mass is preferable, 60% by mass is more preferable, and 70% by mass is even more preferable. As the upper limit of the above content ratio, 99.9% by mass is preferable, 99% by mass is more preferable, and 95% by mass is even more preferable.

[0173] (Method for preparing a composition for forming a resist underlayer film) The composition for forming a resist underlayer film is prepared by mixing at least one selected from the group consisting of [A] an acid generating component, [B] an acid group-containing component, [C1] a photo base generator, and [C2] a base-containing component, [E] a solvent, and optional components, if necessary, in a predetermined ratio, and preferably filtering the resulting mixture through a membrane filter having a pore size of 0.5 μm or less. [Examples]

[0174] Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. The measurement methods of various physical property values are shown below.

[0175] [Weight average molecular weight (Mw)] The Mw of the polymer was measured by gel permeation chromatography (detector: differential refractometer) using GPC columns of Tosoh Corporation ("G2000HXL" two and "G3000HXL" one), flow rate: 1.0 mL / min, elution solvent: tetrahydrofuran, column temperature: 40 °C, with monodisperse polystyrene as the standard.

[0176] [Average thickness of the film] The average thickness of the film was determined as a value obtained by measuring the film thickness at any 9 positions at 5 cm intervals including the center of the resist underlayer film and the metal-containing resist film using a spectroscopic ellipsometer ("M2000D" manufactured by J.A. WOLLAM) and calculating the average value of those film thicknesses.

[0177] [Preparation of a composition for forming a resist underlayer film] The [A] acid generating component, [B] acid group-containing component, [C1] photo-base generator, [C2] base-containing component, [D1] organic polymer, [D2] inorganic polymer, [D4] additive, and [E] solvent used in the preparation of the lower layer film-forming composition are shown below.

[0178] ([A] acid generating component) [A1] Compounds (A-1) to (A-3) which are thermal acid generators and [A2] thermal acid generating polymer (A-4) are shown below. A-1: Compound represented by the following formula (a-1) A-2: Compound represented by the following formula (a-2) A-3: Compound represented by the following formula (a-3) A-4: Resin represented by the following formula (a-4) (Mw: 3,000)

[0179]

Chemical formula

[0180] [A3] Compounds (A-5) to (A-6) which are photo acid generators are shown below. A-5: Compound represented by the following formula (a-5) A-6: Compound represented by the following formula (a-6)

[0181]

Chemical formula

[0182] ([B] acid group-containing component) [B2] Resin (B-1) which is an acid group-containing polymer is shown below. B-1: Acid group-containing polymer represented by the following formula (b-1) (Mw: 3,000)

Chemical formula

[0183] ([C1] photo-base generator) C1-1: Compound represented by the following formula (c1-1) C1-2: A compound represented by the following formula (c1-2) C1-3: A compound represented by the following formula (c1-3)

[0184]

Chemical formula

[0185] ([C2] Base-containing component) C2-1: A compound represented by the following formula (c2-1)

Chemical formula

[0186] ([D1] Organic polymer and [D2] inorganic polymer) [D1] Organic polymers (D1-1) to (D1-6) and [D2] inorganic polymers (D2-1-1) to (D2-1-4), (D-2-1) to (D2-2-2) are shown below. D1-1: An organic polymer represented by the following formula (c-1) (Mw: 2,000) D1-2: An organic polymer represented by the following formula (c-2) (Mw: 1,100) D1-3: An organic polymer represented by the following formula (c-3) (Mw: 2,000) D1-4: An organic polymer represented by the following formula (c-4) (Mw: 1,800) D1-5: An organic polymer represented by the following formula (c-5) (Mw: 2,800) D1-6: An organic polymer represented by the following formula (c-6) (Mw: 2,000) D2-1-1: An inorganic polymer represented by the following formula (c-7) (Mw: 1,500) D2-1-2: An inorganic polymer represented by the following formula (c-8) (Mw: 2,000) D2-1-3: An inorganic polymer represented by the following formula (c-9) (Mw: 2,000) D2-1-4: An inorganic polymer represented by the following formula (c-10) (Mw: 3,000) D2-2-1: An inorganic polymer represented by the following formula (c-11) (Mw: 2,500) D2-2-2: Inorganic polymer represented by the following formula (c-12) (Mw: 3,000)

[0187] [Chemical formula]

[0188] [Chemical formula]

[0189] [Synthesis of [D2-3] polycarbosilane which is an inorganic polymer] The monomers used in the synthesis in this example are shown below. In the following Synthesis Examples 1 to 10, unless otherwise specified, parts by mass mean the values when the total mass of the monomers used or the mass of the diisopropyl ether solution of polycarbosilane (g) is 100 parts by mass. Mol% means the value when the total number of moles of Si in the monomers used is 100 mol%.

[0190] [Chemical formula]

[0191] [Concentration of [D2-3] polycarbosilane in solution] The mass of the residue after firing 0.5 g of the solution of [D2-3] polycarbosilane at 250 °C for 30 minutes was measured, and the concentration (mass%) of [D2-3] polycarbosilane in the solution was calculated by dividing the mass of this residue by the mass of the solution of [D2-3] polycarbosilane.

[0192] (Synthesis of polycarbosilane (g)) [Synthesis Example 1] (Synthesis of polycarbosilane (g-1)) In a nitrogen-substituted reaction vessel, magnesium (120 mol%) and tetrahydrofuran (35 parts by mass) were added and stirred at 20°C. Next, the compound represented by the above formula (H-1), the compound represented by the above formula (S-2), and the compound represented by the above formula (S-3) were dissolved in tetrahydrofuran (355 parts by mass) so that the molar ratio was 50 / 15 / 35 (mol%) to prepare a monomer solution. The inside of the reaction vessel was set at 20°C, and the above monomer solution was added dropwise over 1 hour while stirring. The end of the addition was taken as the start time of the reaction, and the polymerization reaction was carried out at 40°C for 1 hour and then at 60°C for 3 hours. After completion of the reaction, tetrahydrofuran (213 parts by mass) was added, and the polymerization solution was cooled with ice to 10°C or lower. After adding triethylamine (150 mol%) to the cooled polymerization solution, methanol (150 mol%) was added dropwise from a dropping funnel over 10 minutes while stirring. The end of the addition was taken as the start time of the reaction, and the reaction was carried out at 20°C for 1 hour. The polymerization solution was poured into diisopropyl ether (700 parts by mass), and the precipitated salt was filtered off. Next, using an evaporator, tetrahydrofuran, excess triethylamine, and excess methanol in the filtrate were removed. The obtained residue was poured into diisopropyl ether (180 parts by mass), the precipitated salt was filtered off, and diisopropyl ether was added to the filtrate to obtain a diisopropyl ether solution of polycarbosilane (g-1). The concentration of polycarbosilane (g-1) in the above diisopropyl ether solution was 10% by mass. The Mw of polycarbosilane (g-1) was 700.

[0193] [Synthesis Examples 2 to 5] (Synthesis of Polycarbosilanes (g-2) to (g-5)) Except for using each monomer of the types and amounts shown in Table 1 below, diisopropyl ether solutions of polycarbosilanes (g-2) to (g-5) were obtained in the same manner as in Synthesis Example 1. The Mw of polycarbosilane (g) in the obtained solution of polycarbosilane (g) and the concentration (% by mass) of polycarbosilane (g) in the above diisopropyl ether solution are shown in accordance with Table 1. "-" in Table 1 indicates that the corresponding monomer was not used.

[0194] [Table 1]

[0195] [Synthesis Example 6] (Synthesis of Polycarbosilane (D2-3-1)) In a reaction vessel, a diisopropyl ether solution of polycarbosilane (g-1) was dissolved in 90 parts by mass of methanol. The inside of the reaction vessel was set at 30°C, and while stirring, 8 parts by mass of a 3.2% by mass aqueous oxalic acid solution was added dropwise over 20 minutes. The end of the dropwise addition was taken as the start time of the reaction, and the reaction was carried out at 40°C for 4 hours. After completion of the reaction, the inside of the reaction vessel was cooled to 30°C or lower. After adding 198 parts by mass of propylene glycol monomethyl ether acetate to the cooled reaction solution, water, alcohols produced by the reaction, and excess propylene glycol monomethyl ether acetate were removed using an evaporator to obtain a propylene glycol monomethyl ether acetate solution of polycarbosilane (D2-3-1). The concentration of polycarbosilane (D2-3-1) in this propylene glycol monomethyl ether acetate solution was 5% by mass. The Mw of polycarbosilane (D2-3-1) was 2,500.

[0196] [Synthesis Examples 7 to 10] (Synthesis of Polycarbosilanes (D2-3-2) to (D2-3-5)) Propylene glycol monomethyl ether acetate solutions of polycarbosilanes (D2-3-2) to (D2-3-5) were obtained in the same manner as in Synthesis Example 6, except that polycarbosilanes (g-2) to (g-5) were used. The concentrations of these polycarbosilanes (D2-3-2) to (D2-3-5) in the propylene glycol monomethyl ether acetate solution were 5% by mass. The Mw of polycarbosilane (D2-3-2) was 1,800, the Mw of polycarbosilane (D2-3-3) was 2,100, the Mw of polycarbosilane (D2-3-4) was 1,300, and the Mw of polycarbosilane (D2-3-5) was 1,800.

[0197] ([D2-3] Polycarbosilane) D2-3-1: The above-synthesized polycarbosilane (D2-3-1) (Mw: 2,500) D2-3-2: The synthesized polycarbosilane (D2-3-2) (Mw: 1,800) D2-3-3: The synthesized polycarbosilane (D2-3-3) (Mw: 2,100) D2-3-4: The synthesized polycarbosilane (D2-3-4) (Mw: 1,300) D2-3-5: The synthesized polycarbosilane (D2-3-5) (Mw: 1,800)

[0198] ([D4] Additive) [D4-1] Compounds (D-1) to (D-3) which are crosslinking agents and [D4-2] compound (D-4) which is a crosslinking accelerator are shown below. D-1: Compound represented by the following formula (d-1) D-2: Compound represented by the following formula (d-2) D-3: Compound represented by the following formula (d-3) D-4: Compound represented by the following formula (d-4)

[0199]

Chemical formula

[0200] ([E] Solvent) [E-1] to [E-2] solvents which are [E] solvents are shown below. E-1: Propylene glycol monomethyl ether acetate E-2: Propylene glycol monoethyl ether

[0201] [Example 1] 0.3 part by mass of the thermal acid generator (A-1) and 2.7 parts by mass of the organic polymer (D1-2) were dissolved in 97.0 parts by mass of the solvent (E-1). This solution was filtered through a membrane filter with a pore size of 0.45 μm to prepare a composition (J-1) for forming a resist lower layer film.

[0202] [Examples 2 to 43] Except for using the components of the types and contents shown in Table 2, the same operations as in Example 1 were carried out to prepare resist underlayer film-forming compositions (J-2) to (J-43). In Table 2, "-" indicates that the corresponding component was not used.

[0203]

Table 2

[0204] <Fabrication of substrate> [Fabrication of substrate (S-1)] A substrate (S-1) having a silicon dioxide film with a thickness of 20 nm formed on a 12-inch silicon wafer was prepared.

[0205] [Fabrication of substrate (S-2)] A substrate (S-2) having a silicon carbide film with a thickness of 20 nm formed on a 12-inch silicon wafer was prepared.

[0206] [Fabrication of substrate (S-3)] On the above-prepared substrate (S-1), the above-prepared resist underlayer film-forming composition was coated by a spin coating method using a spin coater ("CLEAN TRACK ACT12" manufactured by Tokyo Electron Limited), and heated at 250°C for 60 seconds to form a resist underlayer film with an average thickness of 5 nm, thereby preparing a substrate (S-3).

[0207] <Formation of metal-containing resist film> On the surface of the above-prepared substrate (S-1), substrate (S-2) or substrate (S-3), Sn(CH3)4 was deposited by a CVD apparatus at a pressure maintained at about 1 Torr at 20°C to form a metal-containing resist film with a thickness of 2 nm.

[0208] <Formation of resist pattern> The prepared metal-containing resist film was irradiated with extreme ultraviolet light using an EUV scanner (ASML's "TWINSCAN NXE:3300B" (NA 0.3, Sigma 0.9, quadrupole illumination, mask with a 1:1 line and space of line width 16 nm on the wafer)). Thereafter, an evaluation substrate with a resist pattern formed thereon was obtained by heating at 200 °C for 60 seconds.

[0209] <Evaluation> Regarding the pattern rectangularity, evaluation was performed according to the following method. The evaluation results are shown in Table 3 below. "-" in Table 3 indicates that the composition for forming the resist underlayer film was not coated.

[0210] [Pattern Rectangularity] For the measurement and observation of the resist pattern of the above evaluation substrate, a scanning electron microscope ("SU8220" of Hitachi High-Technologies Corporation) was used. The pattern rectangularity was evaluated as "A" (good) when the cross-sectional shape of the pattern was rectangular, "B1" (bad) when there was a trailing edge in the cross-section of the pattern, and "B2" (bad) when there was a collapse of the resist pattern.

[0211] [Table 3]

[0212] As can be seen from the results in Table 3, in the examples where the resist underlayer film was formed, the pattern rectangularity was excellent compared to the comparative examples where the resist underlayer film was not formed. [Industrial Applicability]

[0213] According to the method for manufacturing a semiconductor substrate of the present invention, since a composition for forming a resist underlayer film having excellent pattern rectangularity is used, a semiconductor substrate having a good pattern shape can be efficiently manufactured. Therefore, the method for manufacturing the semiconductor substrate can be suitably used for the manufacture of semiconductor devices and the like, which are expected to be further miniaturized in the future.

Claims

1. A step of coating a resist underlayer film forming composition directly or indirectly on a substrate; A step of forming a metal-containing resist film on the resist underlayer film formed by the resist underlayer film forming composition coating step; A step of exposing the metal-containing resist film; A step of forming a resist pattern by volatilizing a part of the exposed metal-containing resist film; comprising; The resist underlayer film forming composition is; at least one selected from the group consisting of a photo-base generator and a base-containing component; a solvent; A method for manufacturing a semiconductor substrate containing.

2. The method for manufacturing a semiconductor substrate according to claim 1, wherein the metal-containing resist film is formed by depositing a metal compound.

3. The method for manufacturing a semiconductor substrate according to claim 2, wherein the deposition is by CVD or ALD.

4. The method for manufacturing a semiconductor substrate according to claim 2 or claim 3, wherein the metal compound is represented by the following formula (1). M(X) ４ (1) (In formula (1), M is Sn or Hf. X is, independently of each other, a halogen atom or an alkyl group.)

5. The above metal compound is Sn(CH ３ ), ４ Sn(Br) ４ and HfCl ４ The method for manufacturing a semiconductor substrate according to any one of claims 2 to 4, which is at least one selected from the group consisting of

6. The method for manufacturing a semiconductor substrate according to claim 1, wherein the metal atom contained in the metal-containing resist film is at least one selected from the group consisting of Sn and Hf.

7. The method for manufacturing a semiconductor substrate according to any one of claims 1 to 6, wherein the exposure is exposure by extreme ultraviolet rays.

8. The method for manufacturing a semiconductor substrate according to any one of claims 1 to 7, wherein a resist pattern is formed by volatilizing the unexposed portion of the exposed metal-containing resist film.

9. The method for manufacturing a semiconductor substrate according to any one of claims 1 to 8, wherein a resist pattern is formed by volatilizing a part of the metal-containing resist film by heating the exposed metal-containing resist film.

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