Resist pattern formation method

Abstract

In the present invention, in a semiconductor device manufacturing process, forming a multilayer structure of a metal oxide (e.g., copper oxide) and a resist underlayer film on a stepped metal substrate reduces exposure reflectance from the substrate, thereby reducing standing waves of the resist pattern (defects caused by reflection) and providing a favorable rectangular resist pattern on the substrate. Provided is a pattern-equipped substrate manufacturing method that includes: a step for performing an oxidation treatment on a substrate containing metal on a surface thereof to form a metal oxide film on the substrate surface; a step for applying a resist on the metal oxide film and conducting baking to form a resist film; a step for exposing a semiconductor substrate covered by the metal oxide film and the resist; and a step for developing the exposed resist film and conducting patterning.

Description

Resist pattern forming method

[0001] The present invention relates to a method for forming a resist pattern, a method for manufacturing a substrate having a resist pattern, a method for manufacturing a semiconductor device, and a method for reducing standing waves in a resist pattern.

[0002] In semiconductor manufacturing, a lithography process is widely known in which a resist underlayer film is provided between a substrate and a resist film formed thereon to form a resist pattern of a desired shape. In recent years, the so-called wiring process (post-process) has become increasingly miniaturized, and metal substrates such as copper substrates are now processed by the lithography process.

[0003] Patent Document 1 discloses a method for producing a resist pattern and a conductor pattern.

[0004] Japanese Patent Application Laid-Open No. 2006-154570

[0005] In a semiconductor device manufacturing process, when a resist underlayer film is used on a metal substrate (e.g., copper) having a step, the resist underlayer film is required to have high film thickness uniformity (conformality) in order to reduce the etching load. Although film thickness uniformity (conformality) can be improved by thinning the resist underlayer film, there is a problem in that reflection from the substrate cannot be sufficiently suppressed, and standing waves are generated in the upper layer resist pattern.

[0006] The present invention encompasses the following.

[0007] [1] A method for producing a substrate having a resist pattern, comprising: a step of performing an oxidation treatment on a substrate containing a metal on a surface thereof to form a metal oxide film (or a film of an oxide of the metal) on the surface of the substrate; a step of applying a resist onto the metal oxide film and baking the resist to form a resist film; a step of exposing the substrate, preferably a semiconductor substrate, coated with the metal oxide film and the resist; and a step of developing and patterning the resist film after exposure.

[0008] [2] A method for producing a resist patterned substrate, comprising: applying a resist underlayer film-forming composition to a substrate containing a metal on its surface, and then heating the composition in the presence of oxygen to form a laminated film in which the resist underlayer film is present on a metal oxide film (or a laminate having a film of the metal oxide on the substrate and a resist underlayer film thereon); applying a resist on the resist underlayer film and baking the composition to form a resist film; exposing the substrate, preferably a semiconductor substrate, coated with the resist underlayer film and the resist; and developing and patterning the resist film after exposure.

[0009] [3] The method for producing a substrate having a resist pattern according to [1] or [2], in which standing waves in the resist pattern are reduced.

[0010] [4] The method for producing a substrate having a resist pattern according to [1], wherein the oxidation treatment is selected from a heat treatment in the presence of oxygen, an oxygen plasma treatment, an ozone treatment, a hydrogen peroxide treatment, and a treatment with an alkaline chemical solution containing an oxidizing agent.

[0011] [5] The method for producing a substrate provided with a resist pattern according to [1] or [2], wherein the metal includes copper.

[0012] [6] The method for producing a substrate provided with a resist pattern according to [2], wherein the resist underlayer film contains a heterocyclic compound.

[0013] [7] The method for producing a substrate provided with a resist pattern according to any one of [2] to [6], wherein the resist underlayer film contains a compound represented by the following formula (I): [In formula (I), A １ ~A ３ are each independently a directly bonded or optionally substituted alkylene group having 1 to 6 carbon atoms, １ ~B ３ each independently represents a direct bond, an ether bond, a thioether bond, or an ester bond; R ４ ~R １２ each independently represents a hydrogen atom, a methyl group, or an ethyl group; Z １ ~Z ３ represents the following formula (II): (In formula (II), n Xs each independently represent an alkyl group, a hydroxyl group, an alkoxy group, an alkoxycarbonyl group, a halogen atom, a cyano group, or a nitro group; R represents a hydrogen atom, an alkyl group, or an arylene group; Y represents an ether bond, a thioether bond, or an ester bond; and n represents an integer of 0 to 4.)

[0014] [8] A method for manufacturing a semiconductor device, comprising: a step of performing an oxidation treatment on a semiconductor substrate containing a metal on its surface to form a metal oxide film (or a film of an oxide of the metal) on the substrate surface; a step of applying a resist onto the metal oxide film and baking the resist to form a resist film; a step of exposing the semiconductor substrate coated with the metal oxide film and the resist; and a step of developing and patterning the resist film after exposure.

[0015] [9] A method for manufacturing a semiconductor device, comprising the steps of: applying a resist underlayer film-forming composition to a semiconductor substrate containing a metal on a surface thereof, and then heating in the presence of oxygen to form a laminated film in which a resist underlayer film is present on a metal oxide film (or a laminate having a film of the metal oxide on the substrate and a resist underlayer film thereon); applying a resist on the resist underlayer film and baking the composition to form a resist film; exposing the resist underlayer film and the semiconductor substrate coated with the resist; and developing and patterning the resist film after exposure.

[0016]

[10] A method for reducing standing waves in a resist pattern, comprising: a step of performing an oxidation treatment on a substrate containing a metal on its surface, preferably a semiconductor substrate, to form a metal oxide film (or a film of an oxide of the metal) on the substrate surface; a step of applying a resist onto the metal oxide film and baking the resist to form a resist film; a step of exposing the substrate, preferably a semiconductor substrate, coated with the metal oxide film and the resist; and a step of developing and patterning the resist film after exposure.

[0017]

[11] A method for reducing standing waves in a resist pattern, comprising: a step of applying a resist underlayer film-forming composition to a substrate containing a metal on its surface, preferably a semiconductor substrate, and then heating in the presence of oxygen to form a laminated film in which a resist underlayer film is present on a metal oxide film (or a laminate having a film of an oxide of the metal on the substrate and a resist underlayer film thereon); a step of applying a resist on the resist underlayer film and baking the resist to form a resist film; a step of exposing the resist underlayer film and the substrate, preferably a semiconductor substrate, coated with the resist; and a step of developing and patterning the resist film after exposure.

[0018] Metal oxide films (e.g., copper oxide films) exhibit a high n / k (refractive index / absorption coefficient) value, for example, at i-line (365 nm). Therefore, in the lithography process for manufacturing semiconductor devices, forming a metal oxide film (e.g., copper oxide) on the surface of a semiconductor substrate in advance, or forming a laminate structure of a metal oxide film (e.g., copper oxide) and a resist underlayer film, reduces the reflectance of the substrate upon exposure, thereby reducing standing waves (reflection-related defects) in the resist pattern and enabling the production of a good rectangular resist pattern on a substrate (e.g., a copper substrate). By applying this manufacturing method, it is possible to manufacture substrates with well-shaped resist patterns and semiconductor devices manufactured using the resist patterns. Furthermore, a method for reducing defects (standing waves) in the resist pattern during the lithography process for semiconductor devices can also be provided.

[0019] <Method for manufacturing a substrate having a resist pattern> The method for manufacturing a substrate having a resist pattern of the present invention includes: a step of performing an oxidation treatment on a substrate containing a metal on its surface to form a metal oxide film on the surface of the substrate; a step of applying a resist onto the metal oxide film and baking the resist to form a resist film; a step of exposing the substrate, preferably a semiconductor substrate, coated with the metal oxide film and the resist; and a step of developing and patterning the resist film after exposure.

[0020] The method for producing a resist-patterned substrate of the present invention may include: a step of applying a resist underlayer film-forming composition to a substrate containing a metal on its surface, and then heating the composition in the presence of oxygen to form a laminated film in which the resist underlayer film is present on a metal oxide film; a step of applying a resist to the resist underlayer film and baking the resist to form a resist film; a step of exposing the substrate, preferably a semiconductor substrate, coated with the resist underlayer film and the resist; and a step of developing and patterning the resist film after exposure.

[0021] The resist pattern may have reduced standing waves. A reduction in standing waves (waviness, standing waves) can be determined by a clear reduction in the standing waves in the resist pattern produced by the method of the present invention, compared to a case in which a metal oxide film is not formed on the substrate surface. In order to reduce the standing waves, it is necessary to reduce the "standing ratio S," an index for quantifying standing waves, as shown in the following formula, as described in JP-A 2000-506288. For example, the calculated reflectance of a laminate film, such as a resist film, optionally a resist underlayer film, a metal oxide film, and a substrate, for forming the resist pattern of the present invention, must be 20% or less, preferably 15% or less, preferably 10% or less, preferably 7% or less, and preferably 6% or less.

[0022]

[0023] where S is the standing ratio, Rt is the interface reflectance between the resist and air, Rb is the interface reflectance between the resist and the underlying substrate, α is the absorption coefficient of the resist for the wavelength of the exposure light source, D is the resist film thickness, and the incident angle θi and refraction angle θr of the exposure light are sinθi / sinθr=n air / n resist are in the relationship (n air , n resist are the refractive indices of air and resist, respectively) (Reference: T. Brunner, Proc. SPIE1466, 297 (1991)).

[0024] <Metal> The metal referred to in the present invention is not particularly limited as long as it is a metal that can be used as a wiring material, etc. in the manufacture of a semiconductor device. Specific examples include iron, copper, tin, and aluminum, with copper and aluminum being particularly preferred, and copper being particularly preferred.

[0025] <Oxidation Treatment> The oxidation treatment referred to in the present invention is not limited as long as it is a method for forming a metal oxide having a certain thickness on the metal substrate, and may be selected from heat treatment in the presence of oxygen, oxygen plasma treatment, ozone treatment, hydrogen peroxide treatment, and treatment with an alkaline chemical solution containing an oxidizing agent.

[0026] <Film Thickness, n / k (Refractive Index / Absorption Coefficient)> (Film Thickness) The film thickness of the metal oxide film referred to in the present invention can be adjusted to an appropriate film thickness by known reflectance simulations, for example, as described in JP-A No. 2000-506288, depending on the n / k (refractive index / absorption coefficient) value for the exposure wavelength, and is, for example, 1 to 100 nm. Therefore, the preferred film thickness range of resist underlayer film / metal oxide film in the present invention is (5 to 300 nm) / (1 to 100 nm).

[0027] (n / k (Refractive Index / Absorption Coefficient)) The n / k values ​​of the metal oxide film and the resist underlayer film used in the present invention are, for example, in the following ranges when the exposure wavelength is 365 nm.

[0028] Metal oxide film: n=1.0 to 4.0, k=0.1 to 2.0 Resist underlayer film: n=1.5 to 2.0, k=0.1 to 0.6

[0029] <Resist Underlayer Film> The resist underlayer film referred to in the present invention is a film disposed under a resist in a lithography step for manufacturing a semiconductor device. There are no limitations on the resist underlayer film as long as it exhibits the effects of the present application, and it may contain a known organic compound or a known heterocyclic compound.

[0030] It may also include known organic or inorganic polymers.

[0031] The resist underlayer film according to the present invention can be produced by applying a known resist underlayer film-forming composition to a substrate and baking the composition.

[0032] For example, the resist underlayer film may contain a heterocyclic compound having a dicyanostyryl group, as described in WO2020 / 255984.

[0033] For example, it may be a compound represented by the following formula (I): [In formula (I), A １ ~A ３ are each independently a directly bonded or optionally substituted alkylene group having 1 to 6 carbon atoms, １ ~B ３ each independently represents a direct bond, an ether bond, a thioether bond, or an ester bond; R ４ ~R １２ each independently represents a hydrogen atom, a methyl group, or an ethyl group; Z １ ~Z ３ represents formula (II). (In formula (II), n Xs each independently represent an alkyl group, a hydroxyl group, an alkoxy group, an alkoxycarbonyl group, a halogen atom, a cyano group, or a nitro group; R represents a hydrogen atom, an alkyl group, or an arylene group; Y represents an ether bond, a thioether bond, or an ester bond; and n represents an integer of 0 to 4.)

[0034] The alkyl group may be a straight-chain or branched alkyl group which may or may not have a substituent, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, an n-hexyl group, an isohexyl group, an n-heptyl group, an n-octyl group, a cyclohexyl group, a 2-ethylhexyl group, an n-nonyl group, an isononyl group, a p-tert-butylcyclohexyl group, an n-decyl group, an n-dodecylnonyl group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, an octadecyl group, a nonadecyl group, and an eicosyl group. Preferably, it is an alkyl group having 1 to 20 carbon atoms, more preferably an alkyl group having 1 to 12 carbon atoms, even more preferably an alkyl group having 1 to 8 carbon atoms, and most preferably an alkyl group having 1 to 4 carbon atoms.

[0035] The alkoxy group includes groups in which an oxygen atom is bonded to the alkyl group described above, such as a methoxy group, an ethoxy group, a propoxy group, and a butoxy group.

[0036] The alkoxycarbonyl group includes a group in which an oxygen atom and a carbonyl group are bonded to the alkyl group, such as a methoxycarbonyl group, an ethoxycarbonyl group, a propoxycarbonyl group, and a butoxycarbonyl group.

[0037] The alkylene group includes a divalent group obtained by removing a hydrogen atom from the alkyl group, such as a methylene group, an ethylene group, a 1,3-propylene group, or a 1,2-propylene group.

[0038] Examples of the arylene group include phenylene, o-methylphenylene, m-methylphenylene, p-methylphenylene, α-naphthylene, β-naphthylene, o-biphenylylene, m-biphenylylene, p-biphenylylene, 1-anthrylene, 2-anthrylene, 9-anthrylene, 1-phenanthrylene, 2-phenanthrylene, 3-phenanthrylene, 4-phenanthrylene, and 9-phenanthrylene. Arylene groups having 6 to 14 carbon atoms are preferred, and arylene groups having 6 to 10 carbon atoms are more preferred.

[0039] The halogen atom generally refers to a fluorine, chlorine, bromine, or iodine atom.

[0040] The ester bond referred to in the present invention includes —COO— and —OCO—.

[0041] The entire disclosure of WO2020 / 255984 is incorporated herein by reference.

[0042] The resist underlayer film of the present invention is a compound represented by the following formula (1): [In the formula, A １ , A ２ , A ３ , A ４ , A ５ , and A ６ represents a hydrogen atom, a methyl group, or an ethyl group, and X １is represented by formula (2), formula (3), formula (4), or formula (0): (In the formula R １ and R ２ each represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 3 to 6 carbon atoms, a benzyl group, or a phenyl group, and the alkyl group having 1 to 6 carbon atoms, the alkenyl group having 3 to 6 carbon atoms, the benzyl group, and the phenyl group may be substituted with a group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, a halogen atom, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, a hydroxy group, a carboxyl group, and an alkylthio group having 1 to 6 carbon atoms; and R １ and R ２ may be bonded to each other to form a ring having 3 to 6 carbon atoms, and R ３ represents a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 3 to 6 carbon atoms, a benzyl group, or a phenyl group, and the phenyl group may be substituted with a group selected from the group consisting of an alkyl group having 1 to 6 carbon atoms, a halogen atom, an alkoxy group having 1 to 6 carbon atoms, a nitro group, a cyano group, a hydroxy group, and an alkylthio group having 1 to 6 carbon atoms; and Q represents a group represented by formula (5) or (6): (Q in the formula １ represents an alkylene group having 1 to 10 carbon atoms, a phenylene group, a naphthylene group, or an anthrylene group, and the alkylene group, phenylene group, naphthylene group, and anthrylene group may each be substituted with an alkyl group having 1 to 6 carbon atoms, a carbonyloxyalkyl group having 2 to 7 carbon atoms, a halogen atom, an alkoxy group having 1 to 6 carbon atoms, a phenyl group, a nitro group, a cyano group, a hydroxy group, an alkylthio group having 1 to 6 carbon atoms, a group having a disulfide group, a carboxyl group, or a group consisting of a combination thereof; n １ and n ２ Each represents the number 0 or 1, and X ２ represents formula (2), formula (3), or formula (0)].

[0043] The resist underlayer film according to the present invention may be derived from a resist underlayer film-forming composition described in WO 2020 / 255985, which contains a polymer (P) having a dicyanostyryl group or a compound (C) having a dicyanostyryl group, contains a solvent, does not contain an alkylated aminoplast crosslinking agent derived from melamine, urea, benzoguanamine, or glycoluril, and does not contain a protonic acid curing catalyst.

[0044] The resist underlayer film forming composition of the present invention is described in JP-A-11-511194, comprising: 1. a. a dye-grafted hydroxyl-functional oligomeric reaction product of a preselected phenol- or carboxylic acid-functional dye with a poly(epoxide) resin having an epoxy functionality of greater than 2.0 and less than 10, the product having light-absorbing properties useful for underlayer ARC coatings; b. an alkylated aminoplast crosslinker derived from melamine, urea, benzoguanamine, or glycoluril; c. a protonic acid cure catalyst; and d. a solvent system comprising a low to medium boiling alcohol, the alcohol comprising at least twenty (20) weight percent of the total solvent content and the molar ratio of the alcohol per equivalent methylol unit of the aminoplast is at least four to one (4:1); and e. Improved ARC compositions may be derived from the improved ARC compositions having ether or ester linkages derived from poly(epoxide) molecules, which eliminate intermixing of resist / ARC components through the thermal curing action of the ARCs, provide improved optical density at target exposures and ARC layer thicknesses, and eliminate the need for high molecular weight thermoplastic ARC binders that exhibit high solubility differentials.

[0045] The resist underlayer film of the present invention may be derived from an antireflective coating composition for use in a microlithographic process, as described in JP 2009-37245 A, wherein the composition contains a polymer, a crosslinking agent, a light-attenuating compound, and a strong acid dispersed or dissolved in a solvent system; the polymer is selected from the group consisting of acrylic polymers, polyesters, epoxy novolacs, polysaccharides, polyethers, polyimides, and mixtures thereof; the crosslinking agent is selected from the group consisting of amino resins and epoxy resins; the light-attenuating compound is selected from the group consisting of phenol compounds, carboxylic acids, phosphoric acids, cyano compounds, benzene, naphthalene, and anthracene; and the strong acid is contained in an amount of less than 1.0% by mass, where the total mass of the composition is 100% by mass, and the strong acid is selected from the group consisting of p-toluenesulfonic acid, sulfuric acid, hydrochloric acid, hydrobromic acid, nitric acid, trifluoroacetic acid, and perchloric acid.

[0046] The entire disclosures of WO2013 / 018802, WO2020 / 255985, JP-A-11-511194 and JP-A-2009-37245 are incorporated herein by reference.

[0047] Alternatively, the resist underlayer film may contain a compound represented by the following formula:

[0048] The resist underlayer film may include a polymer containing a unit structure represented by the following formula:

[0049] (In the formula, m, n, and l represent the number of repeating units or the copolymerization molar ratio.)

[0050] <Method for manufacturing semiconductor device, resist underlayer film, and method for forming resist pattern> The method for manufacturing a semiconductor device of the present invention includes the steps of: performing an oxidation treatment on a substrate containing a metal on its surface to form a metal oxide film on the substrate surface; applying a resist onto the metal oxide film and baking the resist to form a resist film; exposing the metal oxide film and the semiconductor substrate coated with the resist; and developing and patterning the resist film after exposure.

[0051] The method for manufacturing a semiconductor device of the present invention may include the steps of: applying a resist underlayer film-forming composition to a substrate containing a metal on its surface, and then heating the composition in the presence of oxygen to form a laminated film in which the resist underlayer film is present on a metal oxide film; applying a resist onto the resist underlayer film and baking the resist to form a resist film; exposing the resist underlayer film and the semiconductor substrate coated with the resist; and developing and patterning the resist film after exposure.

[0052] [Substrate] In the present invention, the substrate (semiconductor substrate) used in the manufacture of a semiconductor device includes, for example, a silicon wafer substrate, a silicon / silicon dioxide coated substrate, a silicon nitride substrate, a glass substrate, an ITO substrate, a polyimide substrate, and a low dielectric constant material (low-k material) coated substrate.

[0053] Recently, in the field of three-dimensional packaging in semiconductor manufacturing processes, the FOWLP process has begun to be applied in order to shorten the wiring length between semiconductor chips, thereby achieving high-speed response and power saving. In the RDL (redistribution layer) process for creating wiring between semiconductor chips, copper (Cu) is used as the wiring material, and as the copper wiring becomes finer, it becomes necessary to apply an antireflective film (resist underlayer film-forming composition).

[0054] [Method for Producing Resist Underlayer Film and Semiconductor Device] Hereinafter, a method for producing a resist underlayer film and a semiconductor device according to the present invention will be described.

[0055] A known resist underlayer film-forming composition according to the present invention is applied to a substrate (e.g., a substrate containing copper on its surface) used in the manufacture of the above-mentioned semiconductor device by a suitable application method such as a spinner or coater, and then baked to form a resist underlayer film. The resist underlayer film according to the present invention typically contains compounds or polymers for adjusting the refractive index for antireflection, for light absorption, and for adhesion to the materials contained in the resist, an acid generator, a crosslinker, and a solvent. Baking conditions are appropriately selected from a baking temperature of 80°C to 400°C and a baking time of 0.3 to 60 minutes. Preferably, the baking temperature is 150°C to 350°C and the baking time is 0.5 to 2 minutes. The thickness of the underlayer film formed here is, for example, 1 to 1000 nm, or 2 to 500 nm, or 3 to 400 nm, or 5 to 300 nm, or 5 to 200 nm, or 5 to 100 nm, or 5 to 80 nm, or 5 to 50 nm, or 5 to 30 nm, or 5 to 20 nm.

[0056] Furthermore, an inorganic resist underlayer film (hard mask) can be formed on the organic resist underlayer film according to the present invention. For example, a silicon-containing resist underlayer film (inorganic resist underlayer film)-forming composition described in WO 2009 / 104552 A1 can be formed by spin coating, or a Si-based inorganic material film can be formed by CVD or the like.

[0057] Next, a resist film, for example, a photoresist layer, is formed on the resist underlayer film. The photoresist layer can be formed by a well-known method of removing solvent from a coating film made of a resist underlayer film-forming composition, i.e., by applying a photoresist composition solution to the underlayer film and baking it. The photoresist film thickness is, for example, 50 to 10,000 nm, or 100 to 4,000 nm.

[0058] The photoresist formed on the resist underlayer film is not particularly limited as long as it is sensitive to the light used for exposure. Both negative and positive photoresists can be used. Examples include positive photoresists made from a novolak resin and a 1,2-naphthoquinone diazide sulfonic acid ester; chemically amplified photoresists made from a binder having a group that decomposes in the presence of an acid to increase the alkaline dissolution rate and a photoacid generator; chemically amplified photoresists made from a low molecular weight compound that decomposes in the presence of an acid to increase the alkaline dissolution rate of the photoresist, an alkali-soluble binder, and a photoacid generator; and chemically amplified photoresists made from a binder having a group that decomposes in the presence of an acid to increase the alkaline dissolution rate of the photoresist, a low molecular weight compound that decomposes in the presence of an acid to increase the alkaline dissolution rate of the photoresist, and a photoacid generator. Examples include APEX-E (trade name) manufactured by Shipley Chemical Co., Ltd., PAR710 (trade name) manufactured by Sumitomo Chemical Co., Ltd., and SEPR430 (trade name) manufactured by Shin-Etsu Chemical Co., Ltd. Further examples include those disclosed in Proc. SPIE, Vol. 3999, 330-334 (2000), Proc. SPIE, Vol. 3999, 357-364 (2000), and Proc. SPIE, Vol. 3999, 365-374 (2000).

[0059] Next, a resist pattern is formed by irradiating with light or an electron beam and developing. First, exposure is performed through a predetermined mask. Near ultraviolet, far ultraviolet, or extreme ultraviolet (for example, EUV (wavelength 13.5 nm)) is used for exposure. Specifically, i-line (wavelength 365 nm), KrF excimer laser (wavelength 248 nm), ArF excimer laser (wavelength 193 nm), and F ２ An excimer laser (wavelength 157 nm) or the like can be used. Of these, i-line (wavelength 365 nm) is preferred. After exposure, post-exposure baking can be performed as needed. The post-exposure baking is performed under conditions appropriately selected from a heating temperature of 70°C to 150°C and a heating time of 0.3 to 10 minutes.

[0060] In addition, in the present invention, a resist for electron beam lithography can be used instead of a photoresist. Either a negative or positive type electron beam resist can be used. Examples of such resists include chemically amplified resists consisting of an acid generator and a binder having a group that decomposes in the presence of acid to change the alkaline dissolution rate; chemically amplified resists consisting of an alkali-soluble binder, an acid generator, and a low-molecular-weight compound that decomposes in the presence of acid to change the alkaline dissolution rate of the resist; chemically amplified resists consisting of an acid generator, a binder having a group that decomposes in the presence of acid to change the alkaline dissolution rate, and a low-molecular-weight compound that decomposes in the presence of acid to change the alkaline dissolution rate of the resist; non-chemically amplified resists consisting of a binder having a group that decomposes in the presence of an electron beam to change the alkaline dissolution rate; and non-chemically amplified resists consisting of a binder having a moiety that is cleaved by an electron beam to change the alkaline dissolution rate. When using these electron beam resists, resist patterns can be formed in the same manner as when using a photoresist using an electron beam as the irradiation source.

[0061] Next, development is carried out with a developer, whereby, for example, when a positive photoresist is used, the photoresist in the exposed portion is removed, and a photoresist pattern is formed.

[0062] Examples of the developer include aqueous alkaline solutions such as aqueous solutions of alkali metal hydroxides such as potassium hydroxide and sodium hydroxide, aqueous solutions of quaternary ammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide and choline, and aqueous solutions of amines such as ethanolamine, propylamine and ethylenediamine. Furthermore, surfactants and the like can also be added to these developers. Development conditions are appropriately selected from a temperature of 5 to 50°C and a time of 10 to 600 seconds.

[0063] In the present invention, an organic underlayer film (lower layer) is formed on a substrate, and then an inorganic underlayer film (middle layer) is formed thereon, and a photoresist (upper layer) is then coated on top of that. This narrows the pattern width of the photoresist, and even if the photoresist is thinly coated to prevent pattern collapse, it is possible to process the substrate by selecting an appropriate etching gas. For example, a fluorine-based gas that has a sufficiently high etching rate for the photoresist can be used as the etching gas to process the resist underlayer film, and a fluorine-based gas that has a sufficiently high etching rate for the inorganic underlayer film can be used as the etching gas to process the substrate, and an oxygen-based gas that has a sufficiently high etching rate for the organic underlayer film can be used as the etching gas to process the substrate.

[0064] The inorganic underlayer film is then removed using the photoresist pattern thus formed as a protective film, and then the organic underlayer film is removed using the film consisting of the patterned photoresist and inorganic underlayer film as a protective film. Finally, the semiconductor substrate is processed using the patterned inorganic underlayer film and organic underlayer film as protective films.

[0065] First, the inorganic underlayer film is removed by dry etching from the portion where the photoresist has been removed, to expose the semiconductor substrate. The dry etching of the inorganic underlayer film is performed using tetrafluoromethane (CF ４ ), perfluorocyclobutane (C ４ F ８ ), perfluoropropane (C ３ F ８ Gases such as tetrafluoromethane (CF), trifluoromethane, carbon monoxide, argon, oxygen, nitrogen, sulfur hexafluoride, difluoromethane, nitrogen trifluoride and chlorine trifluoride, chlorine, trichloroborane, and dichloroborane can be used. For dry etching of the inorganic underlayer film, it is preferable to use a halogen-based gas, and more preferably a fluorine-based gas. Examples of fluorine-based gases include tetrafluoromethane (CF), ４ ), perfluorocyclobutane (C ４ F ８ ), perfluoropropane (C ３ F ８), trifluoromethane, and difluoromethane (CH ２ F ２ ) etc.

[0066] The organic underlayer film is then removed using the patterned photoresist and inorganic underlayer film as a protective film. Because inorganic underlayer films containing a large amount of silicon atoms are difficult to remove by dry etching with oxygen-based gases, the organic underlayer film is often removed by dry etching with oxygen-based gases.

[0067] Finally, the semiconductor substrate is processed. The semiconductor substrate is preferably processed by dry etching using a fluorine-based gas. The fluorine-based gas may be, for example, tetrafluoromethane (CF ４ ), perfluorocyclobutane (C ４ F ８ ), perfluoropropane (C ３ F ８ ), trifluoromethane, and difluoromethane (CH ２ F ２ ) etc.

[0068] Furthermore, an organic antireflective coating can be formed on the resist underlayer coating before the formation of the photoresist. The antireflective coating composition used therein is not particularly limited, and any one can be selected from those conventionally used in lithography processes. The antireflective coating can be formed by a conventional method, such as coating with a spinner or coater and baking.

[0069] The resist underlayer film formed from the resist underlayer film-forming composition may also absorb light depending on the wavelength of the light used in the lithography process. In such cases, it can function as an antireflective film that prevents light from being reflected from the substrate. Furthermore, the underlayer film formed from the resist underlayer film-forming composition of the present invention can also function as a hard mask. The underlayer film of the present invention can also be used as a layer for preventing interaction between the substrate and the photoresist, a layer having the function of preventing adverse effects on the substrate of materials used in the photoresist or substances generated during exposure of the photoresist, a layer having the function of preventing diffusion of substances generated from the substrate during heating and baking into an upper photoresist layer, and a barrier layer for reducing the poisoning effect of the photoresist layer due to a dielectric layer of the semiconductor substrate.

[0070] In addition, an underlayer film formed from the resist underlayer film-forming composition can be applied to a substrate having via holes formed therein for use in a dual damascene process, and can be used as a filling material capable of filling the holes without gaps. It can also be used as a planarizing material for planarizing the surface of an uneven semiconductor substrate.

[0071] On the other hand, for the purposes of simplifying the process, reducing substrate damage, and reducing costs, a method of wet etching removal using a chemical solution has also been investigated instead of dry etching removal. However, resist underlayer films formed from conventional resist underlayer film-forming compositions inherently need to be cured films with solvent resistance in order to suppress mixing with the resist during resist application. Furthermore, during resist patterning, a developer must be used to resolve the resist, and resistance to this developer is also essential. In the method for producing a resist-patterned substrate of the present invention, the resist underlayer film may be one that can be etched (removed) with a wet etching solution.

[0072] The wet etching solution preferably contains, for example, an organic solvent and may contain an acidic compound or a basic compound. Examples of organic solvents include dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, N-ethylpyrrolidone, ethylene glycol, propylene glycol, and diethylene glycol dimethyl ether. Examples of acidic compounds include inorganic acids and organic acids. Examples of inorganic acids include hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid. Examples of organic acids include p-toluenesulfonic acid, trifluoromethanesulfonic acid, salicylic acid, 5-sulfosalicylic acid, 4-phenolsulfonic acid, camphorsulfonic acid, 4-chlorobenzenesulfonic acid, benzenedisulfonic acid, 1-naphthalenesulfonic acid, acetic acid, propionic acid, trifluoroacetic acid, citric acid, benzoic acid, hydroxybenzoic acid, and naphthalenecarboxylic acid. The basic compound may be an inorganic or organic base. Examples of inorganic bases include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide; quaternary ammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, and choline; and amines such as ethanolamine, propylamine, diethylaminoethanol, and ethylenediamine. The wet etching solution may contain a single organic solvent or a combination of two or more organic solvents. The acidic or basic compound may be a single organic solvent or a combination of two or more organic solvents. The amount of the acidic or basic compound in the wet etching solution is 0.01 to 20 wt %, preferably 0.1 to 5 wt %, and particularly preferably 0.2 to 1 wt %. The wet etching solution is preferably an organic solvent containing a basic compound, and particularly preferably a mixture containing dimethyl sulfoxide and tetramethylammonium hydroxide.

[0073] Recently, the FOWLP (Fan-Out Wafer Level Package) process has begun to be applied in the three-dimensional packaging field of semiconductor manufacturing processes, and the resist underlayer film can be applied in the RDL (rewiring) process for forming copper wiring.

[0074] A typical RDL process is described below, but is not limited to this. First, a photosensitive insulating film is formed on a semiconductor chip, followed by patterning through light irradiation (exposure) and development to open semiconductor chip electrode portions. Next, a copper seed layer is formed by sputtering to form copper wiring, which will serve as wiring components, through a plating process. A resist underlayer film and a photoresist layer are then formed in sequence, followed by light irradiation and development to pattern the resist. Unnecessary resist underlayer film is removed by dry etching, and electrolytic copper plating is performed on the copper seed layer between the exposed resist patterns to form copper wiring, which will serve as the first wiring layer. Unnecessary resist, resist underlayer film, and copper seed layer are then removed by dry etching, wet etching, or both. The formed copper wiring layer is then again coated with an insulating film, and the copper seed layer, resist underlayer film, and resist are formed in this order. Resist patterning, resist underlayer film removal, and copper plating are then performed to form a second copper wiring layer. This process is repeated until the desired copper wiring is formed, and then bumps for electrode extraction are formed.

[0075] The resist underlayer film described in the present invention can be removed by wet etching, and therefore can be particularly suitably used as a resist underlayer film in such an RDL step from the viewpoints of simplifying the process steps and reducing damage to the processed substrate.

[0076] The meanings of other terms used in the above explanation are as described above.

[0077] <Method for Reducing Standing Waves in a Resist Pattern> The method for reducing standing waves in a resist pattern of the present invention includes the steps of: performing an oxidation treatment on a substrate containing a metal on its surface, preferably a semiconductor substrate, to form a metal oxide film on the substrate surface; applying a resist onto the metal oxide film and baking the resist to form a resist film; exposing the substrate, preferably a semiconductor substrate, coated with the metal oxide film and the resist; and developing and patterning the resist film after exposure.

[0078] The method for reducing standing waves in a resist pattern of the present invention may include the steps of: applying a resist underlayer film-forming composition to a substrate containing a metal on its surface, preferably a semiconductor substrate, and then heating the composition in the presence of oxygen to form a laminated film in which the resist underlayer film is present on a metal oxide film; applying a resist to the resist underlayer film and baking the resist to form a resist film; exposing the resist underlayer film and the substrate, preferably a semiconductor substrate, coated with the resist; and developing and patterning the exposed resist film.

[0079] The terms used in the above explanation have the same meanings as described above.

[0080] The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples.

[0081] (Preparation Example 1) [Preparation of Resist Underlayer Film-Forming Composition] To 3.63 g of a solution of the reaction product (solids content 16.78 wt%) produced by a method similar to Synthesis Example 2 of WO 2020 / 255984, 0.12 g of tetramethoxymethylglycoluril (trade name: POWDER LINK [registered trademark] 1174, manufactured by Japan Scientific Industries Co., Ltd.) as a crosslinking agent, 0.006 g of pyridinium-p-toluenesulfonate as a crosslinking catalyst, 0.01 g of Megafac R-30N (trade name, manufactured by DIC Corporation), 134.37 g of propylene glycol monomethyl ether, and 14.93 g of propylene glycol monomethyl ether acetate were added to prepare a solution of a resist underlayer film-forming composition for lithography. The reaction product contains a structure represented by the following formula (A-2):

[0082] [Evaluation of Optical Constants of Copper Oxide Film] To evaluate the optical constants, a copper substrate was baked on a hot plate at 150°C for 10 to 60 minutes to form a copper oxide film on the surface of the copper substrate. The n value (refractive index) and k value (extinction coefficient) of the obtained copper oxide film at a wavelength of 365 nm (i-line wavelength) were measured using a spectroscopic ellipsometer (M-2000D, manufactured by J.A. Woolam). The results are shown in Table 1. The above results indicate that the copper oxide film obtained by baking on a hot plate has appropriate n and k values ​​at 365 nm, and therefore has an anti-reflection function that can suppress reflections (standing waves) from the underlying substrate, which can cause undesirable resist patterns in lithography processes using radiation such as i-line. Therefore, the copper oxide film is useful as a resist underlayer film.

[0083] [Evaluation of Optical Constants of Preparation Example 1] To evaluate the optical constants, the resist underlayer film-forming composition for lithography prepared in Preparation Example 1 was applied to a silicon wafer using a spin coater to a film thickness of about 50 nm, and baked on a hot plate at 200°C for 90 seconds. The n value (refractive index) and k value (attenuation coefficient) of the obtained resist underlayer film at a wavelength of 365 nm (i-line wavelength) were measured using a spectroscopic ellipsometer (VUV-VASE, manufactured by J.A. Woolam). The results are shown in Table 2. From the above results, it can be seen that the resist underlayer film-forming composition obtained in Preparation Example 1 has appropriate n and k values ​​at 365 nm, and therefore has an antireflection function that can suppress reflections (standing waves) from the underlying substrate, which can cause undesirable resist patterns in lithography processes using radiation such as i-lines, and is therefore useful as a resist underlayer film.

[0084] [Evaluation of Resist Pattern Shape] Example 1 An 8-inch diameter copper substrate was baked (fired) on a hot plate at 150°C for 30 minutes to form a copper oxide film (thickness: approximately 20 nm) on the surface of the copper substrate. A commercially available positive resist for i-line exposure was then applied to the substrate using a spin coater to a thickness of approximately 2 μm, and prebaked on a hot plate at 90°C for 3 minutes to form a photoresist laminate. The photoresist laminate was then exposed to i-line light using a stepper (Nikon Corporation, NSR-2205i12D) through a pattern mask for resolution measurement. After exposure, the resist was post-baked at 90°C for 90 seconds and developed using a resist developer, a 2.38% aqueous solution of tetramethylammonium hydroxide (TMAH) (product name: NMD-3, Tokyo Ohka Kogyo Co., Ltd.), to obtain a 0.8 μm 1:1 line-and-space resist pattern. Thereafter, the cross-sectional shape of this resist pattern was observed with a scanning electron microscope, and the degree of waviness due to standing waves in the resist pattern shape was evaluated.

[0085] Example 2 The resist underlayer film-forming composition for lithography prepared in Preparation Example 1 was applied to a copper substrate having a diameter of 8 inches using a spin coater to a thickness of approximately 10 nm, and then baked on a hot plate at 200°C for 90 seconds, thereby simultaneously forming a copper oxide film (thickness: approximately 10 nm) on the surface of the copper substrate and a resist underlayer film-forming composition for lithography on top of it. Next, a general i-line resist was applied to a thickness of approximately 2 μm using a spin coater, and prebaked on a hot plate at 90°C for 3 minutes to form a photoresist laminate. Next, the photoresist laminate was subjected to i-line exposure using a stepper (Nikon Corporation, NSR-2205i12D) through a pattern mask for resolution measurement. After exposure, the resist was post-baked at 90°C for 90 seconds and then developed with a resist developer, a 2.38% aqueous solution of tetramethylammonium hydroxide (TMAH) (product name: NMD-3, manufactured by Tokyo Ohka Kogyo Co., Ltd.), to obtain a 0.8 µm 1:1 line and space resist pattern. The cross-sectional shape of this resist pattern was then observed with a scanning electron microscope to evaluate the degree of waviness due to standing waves in the resist pattern shape.

[0086] Example 3 An 8-inch diameter copper substrate was baked on a hot plate at 150°C for 30 minutes to form a copper oxide film (thickness: approximately 20 nm) on the surface of the copper substrate. The resist underlayer film-forming composition for lithography prepared in Preparation Example 1 was then applied to the substrate using a spin coater to a thickness of approximately 10 nm, and baked on a hot plate at 200°C for 90 seconds to form a resist underlayer film-forming composition for lithography on top of the copper oxide film. A general i-line resist was then applied to the substrate using a spin coater to a thickness of approximately 2 μm, and prebaked on a hot plate at 90°C for 3 minutes to form a photoresist laminate. The photoresist laminate was then subjected to i-line exposure using a stepper (Nikon Corporation, NSR-2205i12D) via a pattern mask for resolution measurement. After exposure, the resist was post-baked at 90°C for 90 seconds and then developed with a resist developer, a 2.38% aqueous solution of tetramethylammonium hydroxide (TMAH) (product name: NMD-3, manufactured by Tokyo Ohka Kogyo Co., Ltd.), to obtain a 0.8 µm 1:1 line and space resist pattern. The cross-sectional shape of this resist pattern was then observed with a scanning electron microscope to evaluate the degree of waviness due to standing waves in the resist pattern shape.

[0087] Comparative Example 1 A commercially available positive resist for i-line exposure was applied to an 8-inch diameter copper substrate using a spin coater to a film thickness of approximately 2 μm, and the substrate was prebaked on a hot plate at 90°C for 3 minutes to form a photoresist laminate. The photoresist laminate was then exposed to i-line light using a stepper (Nikon Corporation, NSR-2205i12D) through a pattern mask for resolution measurement. After exposure, the resist was post-baked at 90°C for 90 seconds and developed with a resist developer, a 2.38% aqueous solution of tetramethylammonium hydroxide (TMAH) (product name: NMD-3, Tokyo Ohka Kogyo Co., Ltd.), to obtain a 0.8 μm 1:1 line-and-space resist pattern. The cross-sectional shape of this resist pattern was then observed using a scanning electron microscope to evaluate the degree of waviness due to standing waves in the resist pattern shape.

[0088] The evaluation criteria for the resist pattern shapes of Examples 1 to 3 and Comparative Example 1 were as follows: if the waviness of the resist pattern shape due to standing waves was large compared to Comparative Example 1, it was marked with "x", and if it was small, it was marked with "o", and the results are shown in the following Table 3. The film thickness of the copper oxide film was measured by observing the cross section of the substrate using a scanning electron microscope. From the above results, Examples 1 to 3 provided resist pattern shapes with less waviness due to standing waves compared to Comparative Example 1. In other words, by using a copper oxide film, or a copper oxide film in combination with a resist underlayer film, it is possible to reduce reflections (standing waves) from the copper substrate during exposure in lithography, and to suppress the undesirable phenomenon of wavy resist pattern shapes after development.

[0089] According to the present invention, in the lithography process for manufacturing semiconductor devices, the exposure reflectance from the substrate is reduced, thereby reducing standing waves (defects caused by reflection) in the resist pattern and making it possible to obtain a good rectangular resist pattern on the substrate.

Claims

1. A method for producing a substrate having a resist pattern, comprising the steps of: A step of performing an oxidation treatment on a substrate containing a metal on its surface to form a metal oxide film on the substrate surface; A step of applying a resist onto the metal oxide film and baking the resist to form a resist film; exposing the metal oxide film and the resist-coated substrate to light; and A step of developing and patterning the resist film after exposure. A method for producing a substrate having a resist pattern, comprising:

2. A method for producing a substrate having a resist pattern, comprising the steps of: A step of applying a resist underlayer film-forming composition to a substrate containing a metal on its surface, and then heating the composition in the presence of oxygen to form a laminate film in which the resist underlayer film is present on a metal oxide film; A step of applying a resist onto the resist underlayer film and baking the resist to form a resist film; exposing the resist underlayer film and the substrate coated with the resist; and A step of developing and patterning the resist film after exposure. A method for producing a substrate having a resist pattern, comprising:

3. The method for producing a substrate provided with a resist pattern according to claim 1 or 2, wherein standing waves in the resist pattern are reduced.

4. 2. The method for producing a substrate provided with a resist pattern according to claim 1, wherein the oxidation treatment is selected from the group consisting of a heat treatment in the presence of oxygen, an oxygen plasma treatment, an ozone treatment, a hydrogen peroxide treatment, and a treatment with an alkaline chemical solution containing an oxidizing agent.

5. The method for producing a substrate provided with a resist pattern according to claim 1 , wherein the metal comprises copper.

6. The method for producing a substrate provided with a resist pattern according to claim 2 , wherein the resist underlayer film contains a heterocyclic compound.

7. The method for producing a substrate provided with a resist pattern according to claim 2 or 6, wherein the resist underlayer film contains a compound represented by the following formula (I): 【Chemistry 18】 [In formula (I), A １ ~A ３ each independently represents an alkylene group having 1 to 6 carbon atoms which may be directly bonded or substituted, B １ ~B ３ each independently represents a direct bond, an ether bond, a thioether bond, or an ester bond, R ４ ~R １２ each independently represents a hydrogen atom, a methyl group, or an ethyl group; Z １ ~Z ３ represents the following formula (II): 【Chemistry 19】 (In formula (II), Each of the n Xs independently represents an alkyl group, a hydroxyl group, an alkoxy group, an alkoxycarbonyl group, a halogen atom, a cyano group, or a nitro group; R represents a hydrogen atom, an alkyl group, or an arylene group; Y represents an ether bond, a thioether bond or an ester bond, and n represents an integer of 0 to 4.

8. A method for manufacturing a semiconductor device, comprising: A step of performing an oxidation treatment on a semiconductor substrate containing a metal on its surface to form a metal oxide film on the substrate surface; A step of applying a resist onto the metal oxide film and baking the resist to form a resist film; exposing the metal oxide film and the semiconductor substrate covered with the resist to light; and A step of developing and patterning the resist film after exposure. A method for manufacturing a semiconductor device comprising the steps of:

9. A method for manufacturing a semiconductor device, comprising: A step of applying a resist underlayer film forming composition to a semiconductor substrate containing a metal on its surface, and then heating the composition in the presence of oxygen to form a laminate film in which the resist underlayer film is present on a metal oxide film; A step of applying a resist onto the resist underlayer film and baking the resist to form a resist film; exposing the resist underlayer film and the semiconductor substrate covered with the resist; and A step of developing and patterning the resist film after exposure. A method for manufacturing a semiconductor device comprising the steps of:

10. A method for reducing standing waves in a resist pattern, comprising the steps of: A step of performing an oxidation treatment on a substrate containing a metal on its surface or a semiconductor substrate to form a metal oxide film on the substrate surface; A step of applying a resist onto the metal oxide film and baking the resist to form a resist film; exposing the metal oxide film and the resist-coated substrate or semiconductor substrate to light; and A step of developing and patterning the resist film after exposure. A method for reducing standing waves in a resist pattern, comprising:

11. A method for reducing standing waves in a resist pattern, comprising the steps of: A step of applying a resist underlayer film forming composition to a substrate containing a metal on its surface or a semiconductor substrate, and then heating the substrate in the presence of oxygen to form a laminated film in which the resist underlayer film is present on a metal oxide film; A step of applying a resist onto the resist underlayer film and baking the resist to form a resist film; exposing the resist underlayer film and the substrate or semiconductor substrate covered with the resist; and A step of developing and patterning the resist film after exposure. A method for reducing standing waves in a resist pattern, comprising:

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