Semiconductor substrate manufacturing method and composition for forming resist underlayer film

Abstract

The present invention aims to provide: a production method for a semiconductor substrate that has excellent pattern rectangularity; and a composition for forming a resist underlayer film. The semiconductor substrate production method comprises: a step in which a resist underlayer film-forming composition is directly or indirectly applied to the substrate; a step in which a metal-containing resist film is formed on the resist underlayer film formed in the resist underlayer film-forming composition coating step; a step in which the metal-containing resist film is exposed; a step in which a developing solution is prepared; and a step in which an exposed section of the exposed metal-containing resist film is dissolved by the developing solution to form a resist pattern.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a semiconductor substrate and a composition for forming a resist underlayer film. [Background technology]

[0002] In a typical pattern formation method used in 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 rays such as electron beams to generate acid in the exposed areas. Then, a chemical reaction catalyzed by this acid generates a difference in dissolution rate in a developer between the exposed and unexposed areas, forming a pattern on a substrate. The formed pattern can be used as a mask or the like in substrate processing. With the advancement of microfabrication technology, such pattern formation methods require improved resist performance. To meet this demand, the types and molecular structures of organic polymers, acid generators, and other components used in radiation-sensitive compositions for forming resist films have been investigated, and their combinations have also been extensively studied (see JP 2000-298347 A). The use of metal-containing compounds instead of organic polymers has also been considered. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-298347 Summary of the Invention [Problem to be solved by the invention]

[0004] Resist patterns formed using the above-mentioned metal-containing compounds may suffer from collapse of the resist pattern or pattern footing at the bottom of the resist film.

[0005] An object of the present invention is to provide a method for manufacturing a semiconductor substrate in which the resist pattern has excellent rectangularity by suppressing collapse of the resist pattern and tailing of the pattern at the bottom of the resist film. [Means for solving the problem]

[0006] In one embodiment, the present invention provides a step of directly or indirectly applying a composition for forming a resist underlayer film to a substrate; forming a metal-containing resist film on the resist underlayer film formed by the resist underlayer film-forming composition coating step; exposing the metal-containing resist film to light; preparing a developer; a step of dissolving the exposed portion of the exposed metal-containing resist film with the developer to form a resist pattern; The present invention relates to a method for manufacturing a semiconductor substrate, comprising:

[0007] In another embodiment, the present invention provides a step of directly or indirectly applying a composition for forming a resist underlayer film to a substrate; forming a metal-containing resist film on the resist underlayer film formed by the resist underlayer film-forming composition coating step; exposing the metal-containing resist film to light; preparing a developer; a step of dissolving the exposed portion of the exposed metal-containing resist film with the developer to form a resist pattern; A composition for forming a resist underlayer film used in a method for producing a semiconductor substrate, comprising: at least one selected from the group consisting of a thermal acid generating component, an acid group-containing component, a photobase generator, and a base-containing component; Solvent and The present invention relates to a composition for forming a resist underlayer film, comprising: [Effects of the Invention]

[0008] According to this method for producing a semiconductor substrate, a composition for forming a resist underlayer film is used that can form a resist underlayer film with excellent resist pattern rectangularity, so that a semiconductor substrate with a good pattern shape can be efficiently produced. According to this composition for forming a resist underlayer film, a resist underlayer film with excellent resist pattern rectangularity can be formed, so that a semiconductor substrate with a good pattern shape can be efficiently produced. Therefore, this method for producing a semiconductor substrate and this composition for forming a resist underlayer film can be suitably used in the production of semiconductor devices, which are expected to become even more miniaturized in the future. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, the method for producing 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 semiconductor substrate>> The method for manufacturing a semiconductor substrate includes a step of directly or indirectly applying a resist underlayer film-forming composition to a substrate (hereinafter also referred to as a "resist underlayer film-forming composition applying step"), a step of forming a metal-containing resist film on the resist underlayer film formed by the resist underlayer film-forming composition applying step (hereinafter also referred to as a "metal-containing resist film forming step"), a step of exposing the metal-containing resist film formed by the metal-containing resist film forming step (hereinafter also referred to as an "exposure step"), a step of preparing a developer (hereinafter also referred to as a "developer preparing step"), and a step of dissolving the exposed portion of the exposed metal-containing resist film in the developer to form a resist pattern (hereinafter also referred to as a "resist pattern forming step"). The developer preparing step may be performed at any stage prior to the resist pattern forming step.

[0011] Each step of the method for manufacturing the semiconductor substrate will be described below.

[0012] [Resist underlayer film forming composition application process] In this step, the composition for forming a resist underlayer film is applied directly or indirectly to a substrate. The method for applying the composition for forming a resist underlayer film is not particularly limited, and can be carried out by any appropriate method such as spin coating, casting coating, or roll coating. This forms a coated film, and the solvent in the composition for forming a resist underlayer film evaporates, 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 coating is heated. Heating the coating film promotes the formation of a resist underlayer film. More specifically, heating the coating film promotes the volatilization of the solvent in the composition for forming a resist underlayer film.

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

[0015] The lower limit of the average thickness of the resist underlayer film formed is preferably 0.5 nm, more preferably 1 nm, and even more preferably 2 nm. The upper limit of the average thickness is preferably 50 nm, more preferably 20 nm, even more preferably 10 nm, and particularly preferably 7 nm. The average thickness is measured as described in the Examples.

[0016] [Metal-containing resist film formation process] In this step, a metal-containing resist film is formed on the resist underlayer film formed in the resist underlayer film-forming composition application step.

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

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

[0019] The deposition temperature by ALD may be 50°C to 600°C. The deposition pressure by ALD may be 100 to 6000 mTorr. The flow rate of the metal compound by ALD may be 0.01 to 10 sccm, and the gas flow rate (CO2, CO, Ar, N2) may be 100 to 10000 sccm. The plasma power by ALD may be 200 to 1000 W per 300 mm wafer station using a high frequency plasma (e.g., 13.56 MHz, 27.1 MHz, or higher).

[0020] Suitable process conditions for CVD deposition include a deposition temperature of about 250°C-350°C (e.g., 350°C), a reactor pressure of less than 6 Torr (e.g., maintained at 1.5-2.5 Torr at 350°C), a plasma power / bias of 200 W per 300 mm wafer station using a high frequency plasma (e.g., 13.56 MHz or higher), a metal compound flow rate of about 100-500 sccm, and a CO2 flow rate of about 1000-2000 sccm.

[0021] Metal compounds include trimethyltin chloride, dimethyltin dichloride, methyltin trichloride, tris(dimethylamino)methyltin(IV), and (dimethylamino)trimethyltin(IV).

[0022] The metal-containing resist film preferably contains an organic tin oxide, such as an oxide of an organic metal, such as haloalkyltin, alkoxyalkyltin, or amidoalkyltin.

[0023] [Exposure process] In this process, the metal-containing resist film formed in the metal-containing resist film forming process is exposed to light. This process results in a difference in solubility in a developer between the exposed and unexposed portions of the metal-containing resist film. More specifically, the solubility in a developer of the exposed portions of the metal-containing resist film is increased.

[0024] The radiation used for exposure can be appropriately selected depending on the type of metal-containing resist film used. Examples include visible light, ultraviolet light, far ultraviolet light, electromagnetic waves such as X-rays and gamma rays, and particle beams such as electron beams, molecular beams, and ion beams. Among these, far ultraviolet light is preferred, 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 preferred, with EUV being even more preferred. In addition, exposure conditions can be appropriately determined depending on the type of metal-containing resist film used.

[0025] EUV exposure induces dimerization of organotin oxides in exposed areas of metal-containing resist films. For example, the organotin oxide CH3Sn(SnO)3 can undergo dimerization upon EUV exposure to produce Sn2((SnO)3)2.

[0026] Furthermore, in this process, after the exposure, post-exposure baking (hereinafter also referred to as "PEB") can be performed to improve the performance of the resist film, such as resolution, pattern profile, and developability. The PEB temperature and PEB time can be appropriately determined depending on the type of material used to form the metal-containing resist film. The lower limit of the PEB temperature is preferably 50°C, more preferably 70°C. The upper limit of the PEB temperature is preferably 500°C, more preferably 300°C. The lower limit of the PEB time is preferably 10 seconds, more preferably 30 seconds. The upper limit of the PEB time is preferably 600 seconds, more preferably 300 seconds.

[0027] [Developer preparation process] In this step, a developer is prepared. Examples of the developer include water, alcohol-based liquids, and ether-based liquids, and two or more of these may be used in combination.

[0028] Examples of the alcohol-based liquid include: Examples of the alcohol include monoalcohol liquids such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, t-butanol, n-pentanol, iso-pentanol, sec-pentanol, t-pentanol, 2-methylpentanol, and 4-methyl-2-pentanol.

[0029] Examples of the ether-based liquid include Examples of suitable solvents include polyhydric alcohol partial ether solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, and propylene glycol monoethyl ether; and polyhydric alcohol partial ether acetate liquids such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate (PGMEA), and propylene glycol monoethyl ether acetate.

[0030] The developer is preferably water or an alcohol-based liquid, more preferably water, ethanol or a combination thereof.

[0031] In this step, heating may be performed. The lower limit of the heating temperature is preferably 20°C, more preferably 30°C. The upper limit of the heating temperature is preferably 70°C, more preferably 60°C.

[0032] [Resist pattern formation process] In this process, the exposed portions of the exposed metal-containing resist film are dissolved in the developer to form a resist pattern. The dimerization product of the organotin oxide in the metal-containing resist film is dissolved in the developer to develop the metal-containing resist film. Specifically, Sn2((SnO)3)2 produced by the dimerization reaction due to EUV exposure is dissolved in the developer to develop the metal-containing resist film and form a resist pattern.

[0033] The temperature of the developer can be appropriately determined depending on the type of material used to form the metal-containing resist film, etc. The lower limit of the developer temperature is preferably 20°C, more preferably 30°C, and even more preferably 40°C. The upper limit of the developer temperature is preferably 70°C, more preferably 60°C. The lower limit of the development time is preferably 10 seconds, more preferably 30 seconds. The upper limit of the development time is preferably 600 seconds, more preferably 300 seconds.

[0034] In this step, the exposed portion of the exposed metal-containing resist film may be dissolved in the developer, followed by washing and / or drying.

[0035] [Etching process] In this process, etching is performed using the resist pattern as a mask. Etching may be performed once or multiple times, i.e., etching may be performed sequentially using the pattern obtained by etching as a mask. Etching methods include dry etching and wet etching. A semiconductor substrate having a predetermined pattern is obtained by the above etching.

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

[0037] <<Composition for forming a resist underlayer film>> The resist underlayer film-forming composition is used in a method for producing a semiconductor substrate, the method comprising the steps of: applying the resist underlayer film-forming composition directly or indirectly to a substrate; forming a metal-containing resist film on the resist underlayer film formed by the resist underlayer film-forming composition application step; exposing the metal-containing resist film; preparing a developer; and dissolving the exposed portion of the exposed metal-containing resist film in the developer to form a resist pattern. Details of each step can be suitably adopted from the steps in the method for producing a semiconductor substrate. The resist underlayer film-forming composition contains [A] an acid generating component, [B] an acid group-containing component, [C1] at least one selected from the group consisting of a photobase generator and [C2] a base-containing component, and [E] a solvent.

[0038] ([A] Acid-generating component) Examples of the acid-generating component [A] include a thermal acid generator (hereinafter also referred to as an [A1] thermal acid generator), a thermal acid-generating polymer (hereinafter also referred to as an [A2] thermal acid-generating polymer), and a photoacid generator (hereinafter also referred to as an [A3] photoacid generator). The acid-generating component [A] may be used alone or in combination of two or more.

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

[0040] The component generated from the thermal acid generator [A1] is preferably a sulfonic acid, more preferably a fluorinated alkylsulfonic acid having 1 to 10 carbon atoms and a sulfonic acid having an alicyclic structure, even more preferably a perfluoroalkylsulfonic acid and 10-camphorsulfonic acid, and particularly preferably trifluoromethanesulfonic acid, nonafluorobutanesulfonic acid, and 10-camphorsulfonic acid.

[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, and 2-nitrobenzyl tosylate.

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

[0043]

[0033] The thermal acid generator [A1] is preferably an onium salt compound, more preferably an iodonium salt compound, and even more preferably bis(4-t-butylphenyl)iodonium trifluoromethanesulfonate, bis(4-t-butylphenyl)iodonium nonafluoro-n-butanesulfonate, or bis(4-t-butylphenyl)iodonium 10-camphorsulfonate.

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

[0045] [A2] Thermal acid-generating polymer The thermal acid-generating polymer [A2] is an organic polymer that generates a component having an acid group (a) by the action of heat. The component generated from the thermal acid-generating polymer [A2] may be a low-molecular-weight 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 preferred.

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

[0047] Examples of the thermal acid-generating polymer [A2] include polymers having structural units incorporating one or more thermal acid generators [A1], with structural units having an alkoxysulfonyl group being preferred. Examples of the alkoxysulfonyl group include alkoxysulfonyl groups having 1 to 20 carbon atoms, with an ethoxysulfonyl group being preferred. Examples of structural units containing an alkoxysulfonyl group are styrene-based structural units containing an aromatic ring substituted with an alkoxysulfonyl group, with a structural unit represented by the following formula being more preferred. The thermal acid-generating polymer [A2] may also have structural units other than the structural unit incorporating the thermal acid generator [A1].

[0048] [ka]

[0049] In the above formula, R 1 is 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 consisting of a combination thereof. R 2 is an alkyl group having 1 to 20 carbon atoms.

[0050] The lower limit of the content of the structural unit incorporating the thermal acid generator [A1] in all structural units constituting the thermal acid-generating polymer [A2] is preferably 1 mol %, more preferably 5 mol %, and the upper limit of the content of the structural unit is preferably 80 mol %, more preferably 60 mol %.

[0051] The thermal acid-generating polymer [A2] may have structural units other than the structural unit in which the thermal acid generator [A1] is incorporated. The structural units are not particularly limited, and examples thereof include those similar to the structural units constituting each resin in the organic polymer [D1] described below.

[0052] The lower limit of the content of the other structural units in all structural units constituting the thermoacid-generating polymer [A2] is preferably 5 mol %, more preferably 10 mol %, and the upper limit of the content of the other structural units is preferably 80 mol %, more preferably 50 mol %.

[0053] When the composition for forming a resist underlayer film contains the thermal acid-generating polymer [A2], the lower limit of the content of the thermal acid-generating polymer [A2] in the components other than the solvent in the composition for forming an underlayer film is preferably 80 mass %, more preferably 90 mass %, and even more preferably 95 mass %, and the upper limit of the content may be 100 mass %.

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

[0055] [A3] The acid generated from the photoacid generator is preferably a sulfonic acid, more preferably a fluorinated alkylsulfonic acid having 1 to 10 carbon atoms and a sulfonic acid having an alicyclic structure, even more preferably a perfluoroalkylsulfonic 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, and diazoketone compounds.

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

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

[0059] [ka]

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

[0061] [ka]

[0062] As the onium salt compound, a suitable combination of the above anions and the above cations can be used.

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

[0064] [ka]

[0065] The photoacid generator [A3] is preferably an onium salt compound, more preferably a sulfonium salt, and even more preferably triphenylsulfonium trifluoromethanesulfonate, triphenylsulfonium nonafluorobutanesulfonate, or triphenylsulfonium camphorsulfonate.

[0066] When the composition for forming a resist underlayer film contains a photoacid generator [A3], the lower limit of the content of the photoacid generator [A3] in the components other than the solvent in the composition for forming an underlayer film is preferably 0.1% by mass, more preferably 1% by mass, and even more preferably 2% by mass, and the upper limit of the content 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) The acid group-containing component [B] is a component other than the acid-generating component [A] that has an acid group (a). The acid group-containing component [B] may be a low molecular weight compound (hereinafter also referred to as the acid group-containing compound [B1]) or an organic polymer (hereinafter also referred to as the acid group-containing polymer [B2]). The acid group-containing component [B] may be used alone or in combination of two or more.

[0068] [[B1] Acid group-containing compound] The acid group-containing compound [B1] is a low molecular weight compound having an acid group (a). Specific examples of the acid group-containing compound [B1] include the same compounds as the components having an acid group (a) generated from the thermal acid generator [A1] described above.

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

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

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

[0072] Examples of ion exchange resins include polymers in which an acid group (a) has been introduced into organic polymers such as styrene polymers, (meth)acrylic polymers, polyester polymers, cellulose, and polytetrafluoroethylene. More specific examples include polymers of sulfonated novolac resins, polymers of sulfonated resol resins, polymers of sulfonated styrene polymers cross-linked with divinylbenzene, and polymers of carboxylated (meth)acrylic polymers cross-linked with divinylbenzene. Examples of novolac resins and resol resins that are sulfonated in ion exchange resins include the same novolac resins and resol resins as those in the organic polymer [D1] described below.

[0073] The structural unit containing the acid group (a) is preferably a structural unit of a novolak resin having a sulfo group introduced therein. Examples of such a structural unit include structural units represented by the following formula:

[0074] [ka]

[0075] The lower limit of the content of the structural unit containing the acid group (a) in all structural units constituting the acid group-containing polymer [B2] is preferably 5 mol %, more preferably 10 mol %, while the upper limit of the content of the structural unit is preferably 80 mol %, more preferably 50 mol %.

[0076] The lower limit of the content of structural units not containing an acid group (a) in all structural units constituting the acid group-containing polymer [B2] is preferably 5 mol %, more preferably 10 mol %, while the upper limit of the content of the structural units is preferably 80 mol %, more preferably 50 mol %.

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

[0078] ([C1] Photobase generator) The photobase generator [C1] is a component that generates a base when exposed to radiation. Examples of the base generated by the photobase generator [C] include amines such as primary amines, secondary amines, and tertiary amines. The photobase generator [C1] can be used alone or in combination of two or more.

[0079] [C1] Examples of the photobase generator include transition metal complexes such as cobalt, orthonitrobenzyl carbamates, α,α-dimethyl-3,5-dimethoxybenzyl carbamates, acyloxyimino compounds, and acetophenone compounds.

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

[0198] of JP-A No. 2017-009673.

[0081] Examples of 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- [[(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, Examples thereof include 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, and bis[[(2,6-dinitrobenzyl)oxy]carbonyl]piperazine.

[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-

[0033] bis[[(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 acyloxyiminos include propionylacetophenone oxime, propionylbenzophenone oxime, propionylacetone oxime, butyrylacetophenone oxime, butyrylbenzophenone oxime, butyrylacetone oxime, adipoylacetophenone oxime, adipoylbenzophenone oxime, adipoylacetone oxime, acroylacetophenone oxime, acroylbenzophenone oxime, and acroylacetone oxime.

[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, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one.

[0085]

[0033] In addition to the above-mentioned compound examples, examples of the photobase generator [C1] include 2-nitrobenzylcyclohexylcarbamate, O-carbamoylhydroxyamide, and O-carbamoylhydroxyamide.

[0086] [C1] As the photobase generator, an acetophenone compound or 2-nitrobenzyl cyclohexyl carbamate is preferred, an acetophenone compound having an α-aminoketone structure or 2-nitrobenzyl cyclohexyl carbamate is more preferred, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one or 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one is even more preferred.

[0087] ([C2] Base-containing component) [C2] Examples of the base-containing component include onium salt compounds that do not decompose under 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] [ka]

[0090] Examples of amines include aliphatic amines, aromatic amines, heterocyclic amines, quaternary ammonium hydroxides, and quaternary ammonium carboxylates.

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

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

[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-oxyquinoline, pyrazine, pyrazole, pyridazine, purine, pyrrolidine, piperidine, piperazine, morpholine, 4-methylmorpholine, 1,5-diazabicyclo[4,3,0]-5-nonene, and 1,8-diazabicyclo[5,3,0]-7undecene.

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

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

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

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

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

[0040] to

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

[0099] The lower limit of Mw of the novolac-based resin, resol-based resin, aromatic ring-containing vinyl-based resin, acenaphthylene-based resin, indene-based resin, polyarylene-based resin, triazine-based resin, fullerene-based resin, or pyrene-based resin is preferably 500, more preferably 1,000, and even more preferably 2,000. Meanwhile, the upper limit of the Mw is preferably 10,000. Furthermore, the lower limit of the ratio of Mw to Mn (Mw / Mn) of these resins is preferably 1.1. Meanwhile, 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 resin is preferably 500, more preferably 700, and even more preferably 1,000. The upper limit of the molecular weight is preferably 5,000, more preferably 3,000, and even more preferably 1,500. When the calixarene resin has a molecular weight distribution, the molecular weight of the calixarene resin refers to the Mw calculated as polystyrene by GPC.

[0101] ([D2]Inorganic polymer) Examples of the inorganic polymer [D2] include polysiloxane [D2-1], complexes (multinuclear complexes) [D2-2] containing multiple metal atoms, oxygen atoms bridging the metal atoms (hereinafter also referred to as "bridging oxygen atoms"), and multidentate ligands coordinated to the metal atoms, and polycarbosilane [D2-3].

[0102] [D2-1] Polysiloxane Examples of the polysiloxane [D2-1] 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 polysiloxane [D2-1] can be used alone or in combination of two or more types.

[0103] [ka]

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

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

[0106] R X1The monovalent organic group represented by the formula (I) is preferably a monovalent hydrocarbon group, a monovalent fluorinated hydrocarbon group, or a monovalent group (α) having a divalent heteroatom-containing group between carbon atoms of the monovalent hydrocarbon group, more preferably a monovalent linear hydrocarbon group, a monovalent aromatic hydrocarbon group, a monovalent fluorinated aromatic hydrocarbon group, or a group containing a heterocycle, and more preferably an alkyl group, an aryl group, a fluoroaryl group, or a group containing a nitrogen-containing heterocycle. Examples of the nitrogen-containing heterocycle include an azocycloalkane ring and an isocyanuric ring.

[0107] Examples of the structural unit (I) include structural units represented by the following formula:

[0108] [ka]

[0109] The lower limit of the content of the structural unit (I) in the polysiloxane [D2-1] is preferably 1 mol %, more preferably 5 mol %, while the upper limit of the content of the structural unit (I) is preferably 60 mol %, more preferably 40 mol %.

[0110] The lower limit of the content of the structural unit (II) in the polysiloxane [D2-1] is preferably 40 mol %, more preferably 60 mol %, while the upper limit of the content of the structural unit (II) is preferably 99 mol %, more preferably 95 mol %.

[0111] The lower limit of the Mw of the polysiloxane [D2-1] is preferably 500, more preferably 800, and even more preferably 1,200. On the other hand, the upper limit of the Mw is preferably 100,000, more preferably 30,000, even more preferably 10,000, and particularly preferably 5,000.

[0112] [D2-2] Complex The metal atom in the [D2-2] complex is preferably titanium, tantalum, zirconium, or tungsten (hereinafter, these may be referred to as "specific metal atoms"), and more preferably titanium or zirconium. These metal atoms may be used alone or in combination of two or more.

[0113] The [D2-2] complex can become a stable dinuclear complex by including bridging oxygen atoms. It is preferable that multiple bridging oxygen atoms be bonded to one metal atom, but for some metal atoms, only one bridging oxygen atom may be bonded to one metal atom. It is preferable that the [C2-2] complex mainly contains a structure in which two bridging oxygen atoms are bonded to one metal atom. Here, "mainly containing" the above structure means that two bridging oxygen atoms are bonded to each of 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.

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

[0115] The multidentate ligand in the [D2-2] complex improves the solubility of the [C2-2] complex, thereby improving the removability of the underlayer film. Preferred multidentate ligands include hydroxy acid esters, β-diketones, β-ketoesters, malonic acid diesters (hereinafter also referred to as "malonic acid diesters") whose α-carbon atom may be substituted, and hydrocarbons having a π bond, or ligands derived from these compounds. These compounds typically form multidentate ligands as anions that have gained one electron, as anions that have lost a proton, or as they remain as such.

[0116] The lower limit of the molar ratio of the polydentate ligand to the metal atom in the [D2-2] complex (polydentate ligand / metal atom) is preferably 1, more preferably 1.5, and even more preferably 1.8, while the upper limit of this ratio is preferably 3, more preferably 2.5, and even more preferably 2.2.

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

[0118] [D2-3] Polycarbosilane [D2-3] Polycarbosilane is a polymer that has Si-C bonds in the main chain.

[0119] The polycarbosilane [D2-3] has, for example, a first structural unit (hereinafter also referred to as "structural unit (i)") represented by the following formula (1). The polycarbosilane [D2-3] may also have a second structural unit (hereinafter also referred to as "structural unit (ii)") represented by the following formula (2) and a third structural unit (hereinafter also referred to as "structural unit (iii)") represented by the following formula (3). The polycarbosilane [D2-3] may be used alone or in combination of two or more types.

[0120] (Structural unit (i)) The structural unit (i) is represented by the following formula (1).

[0121] [ka]

[0122] In the above formula (1), R 1 is a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms. 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 (1) 1Examples of the hydrocarbon group include a substituted or unsubstituted divalent chain hydrocarbon group having 1 to 20 carbon atoms, a substituted or unsubstituted divalent alicyclic hydrocarbon group having 3 to 20 carbon atoms, and a substituted or unsubstituted divalent aromatic hydrocarbon group having 6 to 20 carbon atoms. In this specification, the chain hydrocarbon group includes both linear hydrocarbon groups and branched hydrocarbon groups.

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

[0125] Examples of the 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 unsubstituted divalent aromatic hydrocarbon group having 6 to 20 carbon atoms include a phenylene group, a biphenylene group, a phenyleneethylene group, and a naphthylene group.

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

[0128] R 1 As the alkyl group, an unsubstituted chain saturated hydrocarbon group is preferred, and a methanediyl group or an ethanediyl group is more preferred.

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

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

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

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

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

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

[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 even more preferably an alkyl group or an aryl group.

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

[0139] Examples of the halogen atom represented by X or Y include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc. The halogen atom is preferably a chlorine atom or a bromine atom.

[0140] When the [D2-3] polycarbosilane contains the structural unit (I), the lower limit of the content of the structural unit (I) relative to all structural units constituting the [D2-3] polycarbosilane is preferably 5 mol%, more preferably 30 mol%, even more preferably 60 mol%, and particularly preferably 80 mol%. The upper limit of the content of the structural unit (I) may be 100 mol%. By setting the content of the structural unit (I) within the above range, the removability of the silicon-containing film (I) by the removal solution (I) in the semiconductor substrate processing method can be further improved. Note that the content (mol%) of each structural unit in the [D2-3] polycarbosilane is usually equivalent to the molar ratio of the monomers that provide each structural unit used in the synthesis of the [D2-3] polycarbosilane.

[0141] (Structural unit (ii)) The structural unit (ii) is an arbitrary structural unit that the [D2-3] polycarbosilane may have, and is represented by the following formula (2).

[0142] [ka]

[0143] When the polycarbosilane [D2-3] has the structural unit (ii), the lower limit of the content of the structural unit (ii) relative to all structural units constituting the polycarbosilane [D2-3] is preferably 0.1 mol%, more preferably 1 mol%, and even more preferably 5 mol%, while the upper limit of the content 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 arbitrary structural unit that the [D2-3] polycarbosilane may have, and is represented by the following formula (3).

[0145] [ka]

[0146] In the above formula (3), 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, two R 2 are the same or different from each other.

[0147] The above c is preferably 1.

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

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

[0150] When the polycarbosilane [D2-3] has the structural unit (iii), the lower limit of the content of the structural unit (iii) relative to all structural units constituting the polycarbosilane [D2-3] is preferably 0.1 mol%, more preferably 1 mol%, and even more preferably 5 mol%, and the upper limit of the content 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) The aromatic ring-containing compound [D3] is a compound having an aromatic ring and a molecular weight of 600 to 3,000 (excluding the organic polymer [D1] and the inorganic polymer [D2]). When the aromatic ring-containing compound [D3] has a molecular weight distribution, the molecular weight of the aromatic ring-containing compound [D3] means, for example, the weight average molecular weight (Mw) in terms of polystyrene measured by GPC. By including the aromatic ring-containing compound [D3] in the composition for forming a resist underlayer film, the heat resistance and etching resistance of the underlayer film can be improved, similar to when the composition contains the organic polymer [D1] having an aromatic ring. Specific examples of the aromatic ring-containing compound [D3] include the compounds described in paragraphs

[0117] to

[0179] of JP 2016-206676 A.

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

[0153] [D4-1] Crosslinking agent The crosslinking agent [D4-1] is a component that forms crosslinks between the organic polymers [D1], etc., by the action of heat, etc. When the composition for forming a resist underlayer film contains the crosslinking agent [D4-1], the hardness of the underlayer film can be improved.

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

[0155] Examples of hydroxymethyl group-substituted phenol compounds 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), and 5,5'-(1-methylethylidene)bis(2-hydroxy-1,3-benzenedimethanol).

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

[0157] [D4-1] As the crosslinking agent, in addition to the compounds mentioned above, it is also possible to use, for example, a polyfunctional (meth)acrylate compound, an epoxy compound, a hydroxymethyl group-substituted phenol compound, an alkoxyalkyl group-containing phenol compound, etc. Specific examples of these compounds include the compounds described in paragraphs

[0203] to

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

[0158] [D4-1] As the crosslinking agent, a hydroxymethyl-substituted phenol compound and a compound having an alkoxyalkylated 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 the crosslinking agent [D4-1], the lower limit of the content of the crosslinking agent [D4-1] in the components other than the solvent in the composition for forming an underlayer film is preferably 0.1% by mass, more preferably 1% by mass, and even more preferably 2% by mass, and the upper limit of the content 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 The crosslinking accelerator [D4-2] accelerates the formation of crosslinked bonds by the crosslinking agent [D4-1], and hydrolysis condensation by hydrolyzable groups remaining in the polysiloxane [D2-1], the complex [D2-2], etc. As the crosslinking accelerator [D4-2], for example, a nitrogen-containing compound having an acid-dissociable group can be used.

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

[0162] When the composition for forming a resist underlayer film contains the crosslinking accelerator [D4-2], the lower limit of the content of the crosslinking accelerator [D4-2] in the components other than the solvent in the composition for forming an underlayer film is preferably 0.1% by mass, more preferably 1% by mass, and even more preferably 2% by mass, and the upper limit of the content is preferably 20% by mass, more preferably 15% by mass, even 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. Specific examples of the surfactant include those described in paragraph

[0216] of JP-A-2016-206676.

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

[0165] Examples of hydrocarbon solvents 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-based solvents include carbonate-based solvents such as diethyl carbonate, acetate monoester-based solvents such as methyl acetate and ethyl acetate, lactone-based solvents such as γ-butyrolactone, polyhydric alcohol partial ether carboxylate-based solvents such as diethylene glycol monomethyl ether acetate and propylene glycol monomethyl ether acetate, and lactate-based 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 polyalcohol solvents such as ethylene glycol and 1,2-propylene glycol.

[0168] Examples of the ketone solvent 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, polyhydric alcohol ether solvents such as cyclic ether solvents such as tetrahydrofuran, and polyhydric alcohol partial ether solvents such as diethylene glycol monomethyl ether and propylene glycol monomethyl ether.

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

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

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

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

[0174] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Measurement methods for various physical properties 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 (two "G2000HXL" and one "G3000HXL" manufactured by Tosoh Corporation) under the analytical conditions of a flow rate of 1.0 mL / min, elution solvent: tetrahydrofuran, and column temperature: 40°C, with monodisperse polystyrene as the standard.

[0176] [Average film thickness] The average thickness of the film was determined by measuring the film thickness at nine arbitrary positions at 5 cm intervals, including the center of the resist underlayer film, using a spectroscopic ellipsometer (JAWOOLLAM's "M2000D") and calculating the average of these film thicknesses.

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

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

[0179] [ka]

[0180] [A3] Compounds (A-5) and (A-6) which are photoacid generators are shown below. A-5: A compound represented by the following formula (a-5): A-6: A compound represented by the following formula (a-6):

[0181] [ka]

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

[0183] ([C1] Photobase generator) C1-1: A 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] [ka]

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

[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: Organic polymer (Mw: 2,000) represented by the following formula (c-1) D1-2: Organic polymer (Mw: 1,100) represented by the following formula (c-2) D1-3: Organic polymer (Mw: 2,000) represented by the following formula (c-3) D1-4: Organic polymer (Mw: 1,800) represented by the following formula (c-4) D1-5: Organic polymer (Mw: 2,800) represented by the following formula (c-5) D1-6: Organic polymer (Mw: 2,000) represented by the following formula (c-6) D2-1-1: Inorganic polymer (Mw: 1,500) represented by the following formula (c-7) D2-1-2: Inorganic polymer (Mw: 2,000) represented by the following formula (c-8) D2-1-3: Inorganic polymer (Mw: 2,000) represented by the following formula (c-9) D2-1-4: Inorganic polymer (Mw: 3,000) represented by the following formula (c-10) D2-2-1: Inorganic polymer (Mw: 2,500) represented by the following formula (c-11) D2-2-2: Inorganic polymer (Mw: 3,000) represented by the following formula (c-12)

[0187] [ka]

[0188] [ka]

[0189] <[D2] Synthesis of inorganic polymer [D2-3] Polycarbosilane> The monomers used in the synthesis of this example are listed below. In the following Synthesis Examples 1 to 10, unless otherwise specified, parts by mass refer to the total mass of the monomers used or the mass of a diisopropyl ether solution of polycarbosilane (g), taken as 100 parts by mass. Molar % refers to the value when the total number of moles of Si in the monomers used is taken as 100 mole %.

[0190] [ka]

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

[0192] (Synthesis of polycarbosilane (g)) [Synthesis Example 1] (Synthesis of polycarbosilane (g-1)) In a nitrogen-purged reaction vessel, magnesium (120 mol%) and tetrahydrofuran (35 parts by mass) were added and stirred at 20°C. Next, the compound represented by the formula (H-1), the compound represented by the formula (S-2), and the compound represented by the formula (S-3) were dissolved in tetrahydrofuran (355 parts by mass) in a molar ratio of 50 / 15 / 35 (mol%) to prepare a monomer solution. The temperature inside the reaction vessel was raised to 20°C, and the monomer solution was added dropwise over 1 hour with stirring. The end of the dropwise addition marked the start 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 the reaction was completed, tetrahydrofuran (213 parts by mass) was added, and the polymerization solution was cooled to below 10°C with ice. Triethylamine (150 mol%) was added to the cooled polymerization solution, and then methanol (150 mol%) was added dropwise from the dropping funnel over 10 minutes with stirring. The end of the dropwise addition marked the start 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, tetrahydrofuran, excess triethylamine, and excess methanol were removed from the filtrate using an evaporator. The resulting residue was poured into diisopropyl ether (180 parts by mass), and the precipitated salt was filtered off. 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 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)) Diisopropyl ether solutions of polycarbosilanes (g-2) to (g-5) were obtained in the same manner as in Synthesis Example 1, except that the types and amounts of each monomer shown in Table 1 below were used. The Mw of polycarbosilane (g) in the obtained polycarbosilane (g) solution and the concentration (mass %) of polycarbosilane (g) in the diisopropyl ether solution are also shown in 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 temperature inside the reaction vessel was brought to 30°C, and 8 parts by mass of a 3.2% by mass aqueous oxalic acid solution was added dropwise over 20 minutes while stirring. The reaction was initiated when the addition was complete, and was carried out at 40°C for 4 hours. After completion of the reaction, the reaction vessel was cooled to below 30°C. 198 parts by mass of propylene glycol monomethyl ether acetate was added to the cooled reaction solution, and water, alcohols produced by the reaction, and excess propylene glycol monomethyl ether were removed using an evaporator to obtain a propylene glycol monomethyl ether acetate solution of polycarbosilane (D2-3-1). The concentration of this polycarbosilane (D2-3-1) in the 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)) Solutions of polycarbosilanes (D2-3-2) to (D2-3-5) in propylene glycol monomethyl ether acetate were obtained in the same manner as in Synthesis Example 6, except that polycarbosilanes (g-2) to (g-5) were used instead. The concentrations of these polycarbosilanes (D2-3-2) to (D2-3-5) in the propylene glycol monomethyl ether acetate solutions 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: Polycarbosilane (D2-3-1) synthesized above (Mw: 2,500) D2-3-2: Polycarbosilane (D2-3-2) synthesized above (Mw: 1,800) D2-3-3: Polycarbosilane (D2-3-3) synthesized above (Mw: 2,100) D2-3-4: Polycarbosilane (D2-3-4) synthesized above (Mw: 1,300) D2-3-5: Polycarbosilane (D2-3-5) synthesized above (Mw: 1,800)

[0198] ([D4] Additives) [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: A compound represented by the following formula (d-1): D-2: A compound represented by the following formula (d-2): D-3: A compound represented by the following formula (d-3): D-4: A compound represented by the following formula (d-4):

[0199] [ka]

[0200] ([E] solvent) [E] Solvents (E-1) and (E-2) are shown below. E-1: Propylene glycol monomethyl ether acetate E-2: Propylene glycol monoethyl ether

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

[0202] [Examples 2 to 43] Compositions (J-2) to (J-43) for forming resist underlayer films were prepared in the same manner as in Example 1, except that the types and amounts of each component were used as shown in Table 2. In Table 2, "-" indicates that the corresponding component was not used.

[0203] [Table 2]

[0204] <Creating the circuit board> [Preparation of Substrate (S-1)] A substrate (S-1) was prepared by forming a silicon dioxide film with a thickness of 20 nm on a 12-inch silicon wafer.

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

[0206] [Preparation of Substrate (S-3)] The composition for forming a resist underlayer film prepared above was applied onto the substrate (S-1) by a spin coating method using a spin coater (Tokyo Electron Limited's "CLEAN TRACK ACT12"), 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> A metal-containing resist film having a thickness of 5 nm was formed on the surface of the substrate (S-1), substrate (S-2), or substrate (S-3) prepared above using a CVD apparatus at 350°C with a methyltin trichloride flow rate of 200 ccm and a CO flow rate of 1000 sccm.

[0208] <Formation of Resist Pattern> The metal-containing resist film prepared above was irradiated with extreme ultraviolet rays using an EUV scanner (ASML's "TWINSCAN NXE:3300B" (NA 0.3, sigma 0.9, quadrupole illumination, 1:1 line and space mask with a line width of 16 nm on the wafer). The film was then developed by the puddle method for 60 seconds using ethanol / water (volume ratio 70 / 30) heated to 40°C, and then dried to obtain an evaluation substrate on which a resist pattern was formed.

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

[0210] Pattern Rectangularity A scanning electron microscope (Hitachi High-Technologies Corporation's "SU8220") was used to measure and observe the resist patterns on the evaluation substrates. The pattern rectangularity was evaluated as "A" (good) when the cross-sectional shape of the pattern was rectangular, "B1" (poor) when there was footing on the cross-section of the pattern, and "B2" (poor) when there was collapse of the resist pattern.

[0211] [Table 3]

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

[0213] According to the method for producing a semiconductor substrate of the present invention, a composition for forming a resist underlayer film, which has excellent pattern rectangularity, is used, and therefore a semiconductor substrate having a good pattern shape can be efficiently produced. Therefore, the method for producing a semiconductor substrate can be suitably used for the production of semiconductor devices, which are expected to become even more miniaturized in the future.

Claims

1. a step of directly or indirectly applying a composition for forming a resist underlayer film to a substrate; forming a metal-containing resist film on the resist underlayer film formed by the resist underlayer film-forming composition coating step; exposing the metal-containing resist film to light; preparing a developer; a step of dissolving the exposed portion of the exposed metal-containing resist film with the developer to form a resist pattern; Equipped with forming the metal-containing resist film by depositing a metal compound by CVD or ALD; The method for producing a semiconductor substrate, wherein the metal compound comprises at least one selected from the group consisting of haloalkyl Sn, alkoxyalkyl Sn, and amidoalkyl Sn.

2. 2. The method for producing a semiconductor substrate according to claim 1, wherein the metal compound comprises at least one selected from the group consisting of trimethyltin chloride, dimethyltin dichloride, methyltin trichloride, tris(dimethylamino)methyltin(IV), and (dimethylamino)trimethyltin(IV).

3. 2. The method for producing a semiconductor substrate according to claim 1, wherein the metal-containing resist film contains an organotin oxide.

4. 4. The method for manufacturing a semiconductor substrate according to claim 1, wherein the exposure is exposure to extreme ultraviolet light.

5. The method for manufacturing a semiconductor substrate according to claim 1 , wherein the developer contains water, alcohol, or a combination thereof.

6. 6. The method for manufacturing a semiconductor substrate according to claim 1, wherein the temperature of the developer is 40[deg.] C. or higher at least when the exposed area is dissolved.

7. The composition for forming a resist underlayer film, at least one selected from the group consisting of an acid generating component, an acid group-containing component, a photobase generator, and a base-containing component; Solvent and The method for manufacturing a semiconductor substrate according to claim 1 , comprising:

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