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

Technical Field

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

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

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

[0004] Patent Document 1 Japanese Unexamined Patent Publication No. 2006-154570 Summary of the Invention Problem to be Solved by the Invention

[0005] In a semiconductor device manufacturing process, when an underlayer resist film is used on a stepped metal substrate (e.g., a copper substrate), an underlayer resist film with high film thickness uniformity (conformality) is required to reduce etching load. Although thinning the underlayer resist film improves the film thickness uniformity (conformality), reflection from the substrate cannot be sufficiently suppressed, which causes a problem that standing waves are generated in the upper-layer resist pattern. Means for Solving the Problem

[0006] The present invention includes the following.

[0007] [1] A method for manufacturing a substrate with a resist pattern, A step of performing an oxidation treatment on a substrate containing a metal on its surface to form a metal oxide film (or a film of the oxide of the said metal) on the substrate surface. A step of applying a resist onto the metal oxide film and baking it to form a resist film, A step of exposing a substrate coated with the metal oxide film and the resist, preferably a semiconductor substrate, and The process of developing and patterning the resist film after exposure. A method for manufacturing a substrate with a resist pattern, including the method described above.

[0008] [2] A method for manufacturing a substrate with a resist pattern, A step of forming a laminated film (or a laminate having a film of the metal oxide on the substrate and a resist underlayer film thereon) by applying a resist underlayer film forming composition to a substrate containing a metal on its surface, and then heating it in the presence of oxygen, A step of forming a resist film by coating the resist on the resist underlayer film and baking it. A step of exposing the resist underlayer film and the substrate coated with the resist, preferably a semiconductor substrate, and The process of developing and patterning the resist film after exposure. A method for manufacturing a substrate with a resist pattern, including the method described above.

[0009] [3] A method for manufacturing a resist patterned substrate according to [1] or [2], wherein the standing waves of the resist pattern are reduced.

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

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

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

[0013] [7] The method for producing a substrate with a resist pattern according to any one of [2] to [6], wherein the resist underlayer film comprises a compound represented by the following formula (I).

Chemical Formula

Chemical Formula

[0014] [8] A method for manufacturing a semiconductor device, comprising: a step of performing an oxidation treatment on a semiconductor substrate having a metal on a surface thereof to form a metal oxide film (or an oxide film of said metal) on the substrate surface, A step of applying a resist onto the metal oxide film and baking it to form a resist film, A step of exposing a semiconductor substrate coated with the metal oxide film and the resist, and The process of developing and patterning the resist film after exposure. A method for manufacturing a semiconductor device, including the method described above.

[0015] [9] A method for manufacturing a semiconductor device, A step of forming a laminated film (or a laminate having a film of the metal oxide on the substrate and a resist underlayer film thereon) by applying a resist underlayer film forming composition to a semiconductor substrate containing a metal on its surface, and then heating it in the presence of oxygen, A step of forming a resist film by coating the resist on the resist underlayer film and baking it. A step of exposing the resist underlayer film and the semiconductor substrate coated with the resist, and The process of developing and patterning the resist film after exposure. A method for manufacturing a semiconductor device, including the method described above.

[0016]

[10] A method for reducing standing waves in a resist pattern, 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 the oxide of the said metal) on the substrate surface. A step of applying a resist onto the metal oxide film and baking it to form a resist film, A step of exposing a substrate coated with the metal oxide film and the resist, preferably a semiconductor substrate, and The process of developing and patterning the resist film after exposure. A method for reducing standing waves in a resist pattern, including the method described above.

[0017]

[11] A method for reducing standing waves in a resist pattern, A step of forming a laminated film (or a laminate having a film of the metal oxide on the substrate and a resist underlayer film thereon) on a substrate containing a metal on its surface, preferably a semiconductor substrate, by applying a resist underlayer film forming composition to the substrate, and then heating it in the presence of oxygen, A step of forming a resist film by coating the resist on the resist underlayer film and baking it. A step of exposing the resist underlayer film and the substrate coated with the resist, preferably a semiconductor substrate, and The process of developing and patterning the resist film after exposure. A method for reducing standing waves in a resist pattern, including the method described above. [Effects of the Invention]

[0018] Metal oxide films (e.g., copper oxide films) exhibit high n / k (refractive index / absence coefficient) values, for example, for the i-line (365 nm). Therefore, in the lithography process of semiconductor device manufacturing, by pre-forming a metal oxide film (e.g., copper oxide) on the surface of the semiconductor substrate, or by creating a laminated structure of a metal oxide film (e.g., copper oxide) and a resist underlayer film, the exposure reflectance from the substrate is reduced, thereby reducing standing waves (defects due to reflection) in the resist pattern and making it possible to obtain a good rectangular resist pattern on the substrate (e.g., copper substrate). By applying this manufacturing method, it is possible to manufacture substrates with resist patterns having a good shape and semiconductor devices manufactured using said resist patterns. Furthermore, a method for reducing defects (standing waves) in the resist pattern during the lithography process of semiconductor devices can also be provided. [Modes for carrying out the invention]

[0019] <Manufacturing method for substrates with resist patterns> The method for manufacturing a resist patterned substrate according to the present invention is: A process of performing an oxidation treatment on a substrate containing 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 it to form a resist film, A step of exposing a substrate coated with the metal oxide film and the resist, preferably a semiconductor substrate, and The process of developing and patterning the resist film after exposure. This is a method for manufacturing a substrate with a resist pattern, including the following:

[0020] The method for manufacturing a resist patterned substrate according to the present invention is: A process of forming a laminated film in which a resist underlayer film is formed on a substrate containing a metal on its surface by applying a resist underlayer film forming composition, and then heating it in the presence of oxygen, A step of forming a resist film by coating the resist on the resist underlayer film and baking it. A step of exposing the resist underlayer film and the substrate coated with the resist, preferably a semiconductor substrate, and The process of developing and patterning the resist film after exposure. It may include.

[0021] The standing waves of the resist pattern may be reduced. The reduction of standing waves (undulation, standing waves) can be determined by the fact that the standing waves of the resist pattern manufactured by the method of the present invention are clearly reduced compared to the case where a metal oxide film is not formed on the substrate surface. In order for the above-mentioned standing waves to be reduced, it is necessary to reduce the "standing ratio S," which is an index for quantifying standing waves and is shown by the following formula, as described in, for example, Japanese Patent Publication No. 2000-506288. For example, the reflectance calculation result of the laminated film such as the resist film, possibly the resist underlayer film, metal oxide film, and substrate used to form 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]

number

[0023] Here, 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 substrate, α is the absorption coefficient of the resist with respect to 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 given by sinθi / sinθr=n air / n resist (n air , n resist (These are the refractive indices of air and the resist, respectively) (Reference: T. Brunner, Proc. SPIE1466, 297 (1991)).

[0024] <Metal> The metal referred to in this invention is not particularly limited as long as it is a metal used as a wiring material or the like in the manufacture of semiconductor devices. Specific examples include iron, copper, tin, and aluminum, but copper and aluminum are particularly preferred, with copper being especially preferred.

[0025] <Oxidation treatment> The oxidation treatment referred to in this invention is not limited to any method that forms a metal oxide of a certain thickness on the metal substrate, but may be selected from heat treatment in the presence of oxygen, oxygen plasma treatment, ozone treatment, hydrogen peroxide treatment, and alkaline chemical treatment containing an oxidizing agent.

[0026] <Film thickness, n / k (refractive index / absorption coefficient)> (film thickness) The thickness of the metal oxide film in this invention can be adjusted to an appropriate thickness by the n / k (refractive index / absorption coefficient) value with respect to the exposure wavelength, for example by known reflectance simulations described in Japanese Patent Publication No. 2000-506288, etc., but is for example 1 to 100 nm. Therefore, the preferred thickness range for the resist underlayer film / metal oxide film in this 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 this invention are, for example, within the following ranges at an exposure wavelength of 365 nm.

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

[0029] <Underlying resist film> The resist underlayer film referred to in this invention is a film placed beneath the resist in the lithography process of semiconductor device manufacturing. There are no limitations as long as the resist underlayer film achieves the effects of this invention, but it may contain known organic compounds and may contain known heterocyclic compounds.

[0030] Furthermore, it may contain known organic polymers or inorganic polymers.

[0031] The resist underlayer film described in the present invention can be manufactured by coating a known resist underlayer film forming composition onto a substrate and firing it.

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

[0033] For example, the compound may be represented by the following formula (I). [ka] [In formula (I), A1 to A3 are each an alkylene group having 1 to 6 carbon atoms, which may be directly bonded or substituted. B1 to B3 each independently represent a direct bond, an ether bond, a thioether bond, or an ester bond. R4~R 12 Each of these independently represents a hydrogen atom, a methyl group, or an ethyl group. Z1 to Z3 represent equation (II). [ka] (In formula (II), Each of the n X 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, thioether bond, or ester bond. n represents an integer between 0 and 4.

[0034] Examples of the alkyl groups mentioned above include linear or branched alkyl groups that may or may not have substituents, such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, n-hexyl group, isohexyl group, n-heptyl group, n-octyl group, cyclohexyl group, 2-ethylhexyl group, n-nonyl group, isononyl group, p-tert-butylcyclohexyl group, n-decyl group, n-dodecylnonyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, and eicosyl group. Preferably, the alkyl group has 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, even more preferably 1 to 8 carbon atoms, and most preferably 1 to 4 carbon atoms.

[0035] Examples of the alkoxy groups mentioned above include groups in which an oxygen atom is bonded to the alkyl group. These include methoxy groups, ethoxy groups, propoxy groups, and butoxy groups.

[0036] Examples of the alkoxycarbonyl group mentioned above include groups in which an oxygen atom and a carbonyl group are bonded to the alkyl group. For example, methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, butoxycarbonyl group, etc.

[0037] Examples of the alkylene groups mentioned above include divalent groups obtained by further removing hydrogen atoms from the alkyl group. These include methylene groups, ethylene groups, 1,3-propylene groups, and 1,2-propylene groups.

[0038] Examples of the above-mentioned arylene groups include phenylene group, o-methylphenylene group, m-methylphenylene group, p-methylphenylene group, α-naphthylene group, β-naphthylene group, o-biphenylylene group, m-biphenylylene group, p-biphenylylene group, 1-antrylene group, 2-antrylene group, 9-antrylene group, 1-phenanthrylene group, 2-phenanthrylene group, 3-phenanthrylene group, 4-phenanthrylene group, and 9-phenanthrylene group. Preferably, the arylene group has 6 to 14 carbon atoms, and more preferably, the arylene group has 6 to 10 carbon atoms.

[0039] Halogen atoms typically refer to the atoms of fluorine, chlorine, bromine, and iodine.

[0040] The ester bond as used in this invention includes -COO- and -OCO-.

[0041] The full disclosure of WO2020 / 255984 is incorporated into the present application as reference.

[0042] The resist underlayer film referred to in this invention is the following formula (1) described in WO2013 / 018802: [ka] [In the formulas, A1, A2, A3, A4, A5, and A6 represent a hydrogen atom, a methyl group, or an ethyl group, respectively, and X1 is formula (2), formula (3), formula (4), or formula (0): [ka] (In the formula, R1 and R2 each represent 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 are substituted with a group selected from the group consisting of alkyl groups having 1 to 6 carbon atoms, halogen atoms, alkoxy groups having 1 to 6 carbon atoms, nitro groups, cyano groups, hydroxyl groups, carboxyl groups, and alkylthio groups having 1 to 6 carbon atoms.) R1 and R2 may be bonded to each other to form a ring having 3 to 6 carbon atoms, R3 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 alkyl groups having 1 to 6 carbon atoms, halogen atoms, alkoxy groups having 1 to 6 carbon atoms, nitro groups, cyano groups, hydroxyl groups, and alkylthio groups having 1 to 6 carbon atoms), and Q represents formula (5) or formula (6): [ka] The polymer may contain a repeating unit structure represented by the formula (wherein Q1 represents an alkylene group, phenylene group, naphthylene group, or anthrylene group having 1 to 10 carbon atoms, 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 hydroxyl 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, and n1 and n2 each represent the number 0 or 1, and X2 represents formula (2), formula (3), or formula (0)).

[0043] The resist underlayer film referred to in this invention comprises a polymer (P) having a dicyanostyryl group or a compound (C) having a dicyanostyryl group, as described in WO2020 / 255985. Contains solvents, It does not contain alkylated aminoplast crosslinking agents derived from melamine, urea, benzoguanamine, or glycoluryl. Does not contain protonate curing catalysts. It may be derived from a resist underlayer film forming composition.

[0044] The resist underlayer film forming composition of the present invention is described in Japanese Patent Publication No. 11-511194. 1. a. Dye-grafted hydroxyl-functional oligomer reaction product of a pre-selected phenol- or carboxylic acid-functional dye and a poly(epoxide) resin having an epoxy functional value greater than 2.0 and less than 10; the product has light-absorbing properties effective for ARC coating of the base layer; b. Alkylated aminoplast crosslinking agents derived from melamine, urea, benzoguanamine, or glycolyl; c. Protonate curing catalyst; and d. A solvent system containing a low- to medium-boiling point alcohol; in the solvent system, the alcohol accounts for at least 20% by weight of the total solvent content, and the molar ratio of the alcohol is at least 4:1 per equivalent methylol units of the aminoplast; It consists of, and e. Ether or ester bonds derived from poly(epoxide) molecules An improved ARC composition having; The improved ARC may be derived from the improved ARC composition, which eliminates mutual mixing of resist / ARC components by the thermosetting action of ARCs, provides improved optical density in target exposure and ARC layer thickness, and eliminates the need for high molecular weight thermoplastic ARC binders that exhibit large solubility differences.

[0045] The resist underlayer film referred to in the present invention is an anti-reflective coating composition used in a microlithographic process as described in Japanese Patent Application Publication No. 2009-37245, wherein the composition contains a polymer dispersed or dissolved in a solvent system, a crosslinking agent, a light-attenuating compound, and a strong acid. 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. The strong acid may be derived from an anti-reflective coating composition in which the strong acid is contained in less than 1.0% by mass when 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 full disclosures in Japanese Patent Publication No. WO2013 / 018802, WO2020 / 255985, Japanese Patent Publication No. Hei 11-511194, and Japanese Patent Publication No. 2009-37245 are incorporated herein by reference.

[0047] Furthermore, the resist underlayer film may contain a compound represented by the following formula. [ka] [ka]

[0048] The resist underlayer may contain 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.) [ka] [ka] [ka] [ka] [ka] [ka] [ka]

[0050] <Method for manufacturing a semiconductor device, resist underlayer film, resist pattern formation method> The method for manufacturing a semiconductor device of the present invention is: A process of performing an oxidation treatment on a substrate containing 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 it to form a resist film, A step of exposing a semiconductor substrate coated with the metal oxide film and the resist, and The process of developing and patterning the resist film after exposure. Includes.

[0051] The method for manufacturing a semiconductor device of the present invention is: A process of forming a laminated film in which a resist underlayer film is formed on a substrate containing a metal on its surface by applying a resist underlayer film forming composition, and then heating it in the presence of oxygen, A step of forming a resist film by coating the resist on the resist underlayer film and baking it. A step of exposing the resist underlayer film and the semiconductor substrate coated with the resist, and The process of developing and patterning the resist film after exposure. It may include.

[0052] [substrate] In the present invention, substrates used in the manufacture of semiconductor devices (semiconductor substrates) include, for example, silicon wafer substrates, silicon / silicon dioxide coated substrates, silicon nitride substrates, glass substrates, ITO substrates, polyimide substrates, and low-dielectric material (low-k material) coated substrates.

[0053] Recently, in the field of three-dimensional packaging in semiconductor manufacturing processes, the FOWLP process has begun to be applied with the aim of achieving high-speed response and power saving by shortening the wiring length between semiconductor chips. In the RDL (redistribution) process, which creates wiring between semiconductor chips, copper (Cu) is used as the wiring material, and as copper wiring becomes finer, it becomes necessary to apply an anti-reflective film (resist underlayer film forming composition).

[0054] [Method for manufacturing resist underlayer films and semiconductor devices] The following describes the method for manufacturing a resist underlayer film and a semiconductor device according to the present invention.

[0055] A known resist underlayer forming composition, as defined in the present invention, is applied to a substrate used in the manufacture of the semiconductor device described above (for example, a substrate containing copper on its surface) by a suitable coating method such as a spinner or coater, and then fired to form a resist underlayer. The resist underlayer film in this invention typically contains compounds or polymers, acid generators, crosslinking agents, and solvents to adjust the refractive index for anti-reflection, absorb light, and achieve adhesion with the material contained in the resist. The firing conditions are appropriately selected from a firing temperature of 80°C to 400°C and a firing time of 0.3 to 60 minutes. Preferably, the firing temperature is 150°C to 350°C and the firing time is 0.5 to 2 minutes. The thickness of the underlayer film formed 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 (hard mask) can be formed on the organic resist underlayer according to the present invention. For example, in addition to the method of forming the silicon-containing resist underlayer (inorganic resist underlayer) formation composition described in WO2009 / 104552A1 by spin coating, a Si-based inorganic material film can be formed by CVD or the like.

[0057] Next, a resist film, such as a photoresist layer, is formed on the resist underlayer. The photoresist layer can be formed by a well-known method of removing the solvent from the coating film made of the resist underlayer forming composition, i.e., by coating the photoresist composition solution onto the underlayer and firing it. The thickness of the photoresist 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 consisting of novolac resin and 1,2-naphthoquinone diazide sulfonic acid ester, chemically amplified photoresists consisting of a binder having a group that decomposes with acid to increase the alkali dissolution rate and a photoacid generator, chemically amplified photoresists consisting of a low molecular weight compound that decomposes with acid to increase the alkali dissolution rate of the photoresist, an alkali-soluble binder and a photoacid generator, and chemically amplified photoresists consisting of a binder having a group that decomposes with acid to increase the alkali dissolution rate, a low molecular weight compound that decomposes with acid to increase the alkali dissolution rate of the photoresist and a photoacid generator. Examples include APEX-E (Chypre Corporation), PAR710 (Sumitomo Chemical Co., Ltd.), and SEPR430 (Shin-Etsu Chemical Co., Ltd.). Furthermore, examples include fluorine-containing polymer-based photoresists, such as those described 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 irradiation with light or an electron beam and development. First, exposure is performed through a predetermined mask. Near-ultraviolet, far-ultraviolet, or extreme ultraviolet (e.g., 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 F2 excimer laser (wavelength 157 nm) can be used. Among these, i-line (wavelength 365 nm) is preferred. After exposure, post-exposure baking can be performed as needed. 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] Furthermore, in this invention, electron beam lithography resists can be used instead of photoresists as the resist. Both negative and positive electron beam resists can be used. Examples include chemically amplified resists consisting of an acid generator and a binder having a group that decomposes with acid to change the alkali dissolution rate, chemically amplified resists consisting of an alkali-soluble binder, an acid generator, and a low-molecular-weight compound that decomposes with acid to change the alkali dissolution rate of the resist, chemically amplified resists consisting of an acid generator, a binder having a group that decomposes with acid to change the alkali dissolution rate, and a low-molecular-weight compound that decomposes with acid to change the alkali dissolution rate of the resist, non-chemically amplified resists consisting of a binder having a group that decomposes with electron beams to change the alkali dissolution rate, and non-chemically amplified resists consisting of a binder having a portion that is cut by an electron beam to change the alkali dissolution rate. When using these electron beam resists, a resist pattern can be formed in the same way as when using photoresists, with an electron beam as the irradiation source.

[0061] Next, development is performed using a developing solution. This removes the photoresist from the exposed areas, for example, if a positive-type photoresist is used, and a photoresist pattern is formed.

[0062] Examples of developers include 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 alkaline aqueous solutions of amines such as ethanolamine, propylamine, and ethylenediamine. Furthermore, surfactants can 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 this invention, an organic underlayer film (lower layer) can be formed on a substrate, followed by an inorganic underlayer film (intermediate layer), and then a photoresist (upper layer) can be coated on top of that. This narrows the pattern width of the photoresist, and even when the photoresist is thinly coated to prevent pattern collapse, substrate processing becomes possible by selecting an appropriate etching gas. For example, a fluorine-based gas that provides a sufficiently fast etching rate for the photoresist can be used as the etching gas to process the underlayer film of the resist, and a fluorine-based gas that provides a sufficiently fast etching rate for the inorganic underlayer can be used as the etching gas to process the substrate, and an oxygen-based gas that provides a sufficiently fast etching rate for the organic underlayer can be used as the etching gas to process the substrate.

[0064] Then, the inorganic underlayer is removed using the photoresist pattern formed in this way as a protective film, and subsequently, the organic underlayer is removed using the film consisting of the patterned photoresist and inorganic underlayer as a protective film. Finally, the semiconductor substrate is processed using the patterned inorganic and organic underlayers as protective films.

[0065] First, the inorganic underlayer film in the areas where the photoresist has been removed is removed by dry etching to expose the semiconductor substrate. Gases such as tetrafluoromethane (CF4), perfluorocyclobutane (C4F8), perfluoropropane (C3F8), 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 halogen-based gases for dry etching of the inorganic underlayer film, and more preferably fluorine-based gases. Examples of fluorine-based gases include tetrafluoromethane (CF4), perfluorocyclobutane (C4F8), perfluoropropane (C3F8), trifluoromethane, and difluoromethane (CH2F2).

[0066] Subsequently, the organic underlayer is removed using a protective film consisting of a patterned photoresist and an inorganic underlayer. Since inorganic underlayers containing many silicon atoms are difficult to remove by dry etching with oxygen-based gases, organic underlayers are often removed by dry etching with oxygen-based gases.

[0067] Finally, the semiconductor substrate is processed. Preferably, the semiconductor substrate is processed by dry etching using a fluorine-based gas. Examples of fluorinated gases include tetrafluoromethane (CF4), perfluorocyclobutane (C4F8), perfluoropropane (C3F8), trifluoromethane, and difluoromethane (CH2F2).

[0068] Furthermore, an organic anti-reflective coating can be formed on top of the resist underlayer before the photoresist is formed. There are no particular restrictions on the anti-reflective coating composition used; any composition that has been conventionally used in lithography processes can be arbitrarily selected and used, and the anti-reflective coating can be formed by conventional methods, such as coating with a spinner or coater and firing.

[0069] The resist underlayer formed from the resist underlayer forming composition may also have absorption properties for certain wavelengths of light used in the lithography process. In such cases, it can function as an anti-reflective film that prevents reflected light from the substrate. Furthermore, the underlayer formed with the resist underlayer forming composition of the present invention can also function as a hard mask. The underlayer of the present invention can also be used as a layer to prevent interaction between the substrate and the photoresist, a layer that prevents adverse effects on the substrate from materials used in the photoresist or substances generated during exposure to the photoresist, a layer that prevents the diffusion of substances generated from the substrate to the upper photoresist during heating and firing, and a barrier layer to reduce the poisoning effect of the photoresist layer by the semiconductor substrate dielectric layer.

[0070] Furthermore, the underlayer film formed from the resist underlayer film forming composition can be applied to a substrate with via holes formed in a dual damascene process and used as a filler material that can completely fill the holes. It can also be used as a planarizing material to flatten the surface of an uneven semiconductor substrate.

[0071] On the other hand, in order to simplify the process, reduce substrate damage, and lower costs, methods using wet etching with chemicals are being considered as an alternative to dry etching removal. However, conventional resist underlayer compositions require a cured film with solvent resistance in order to suppress mixing with the resist during resist coating. Furthermore, a developer is required to resolve the resist during resist patterning, and resistance to this developer is also essential. In the method for manufacturing a resist-patterned substrate of the present invention, the resist underlayer may be etchable (removable) with a wet etching solution.

[0072] The wet etching solution preferably contains an organic solvent, and may also 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 or 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. Furthermore, basic compounds include inorganic bases or organic bases. 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. In addition, the wet etching solution may use only one organic solvent or a combination of two or more. Furthermore, the acidic compound or basic compound may be used only one or a combination of two or more. The amount of the acidic compound or basic compound added to the wet etching solution is 0.01 to 20% by weight, preferably 0.1 to 5% by weight, and particularly preferably 0.2 to 1% by weight. Preferably, the wet etching solution is 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 field of three-dimensional packaging in semiconductor manufacturing processes, and a resist underlayer can be applied in the RDL (redistribution) process that forms copper wiring.

[0074] In a typical RDL process, the following is described, but this is not limited to this. First, a photosensitive insulating film is deposited on the semiconductor chip, and then the semiconductor chip electrode area is opened by patterning through light irradiation (exposure) and development. Next, a copper seed layer is deposited by sputtering for the formation of copper wiring, which will be the wiring material, through a plating process. Furthermore, a resist underlayer and a photoresist layer are deposited in sequence, and then the resist is patterned by light irradiation and development. Unnecessary resist underlayers are removed by dry etching, and electrolytic copper plating is performed on the copper seed layer between the exposed resist patterns to form the copper wiring that will become the first wiring layer. Furthermore, unnecessary resist, resist underlayers, and copper seed layers are removed by dry etching, wet etching, or both. Furthermore, the formed copper wiring layer is covered again with an insulating film, and then the copper seed layer, resist underlayer, and resist are deposited in that order, and the second copper wiring layer is formed by resist patterning, resist underlayer removal, and copper plating. This process is repeated to form the desired copper wiring, 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 RDL processes from the viewpoint of simplifying the process and reducing damage to the processed substrate.

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

[0077] <Method for reducing standing waves in resist patterns> The present invention provides a method for reducing standing waves in a resist pattern, A process 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. A step of applying a resist onto the metal oxide film and baking it to form a resist film, A step of exposing a substrate coated with the metal oxide film and the resist, preferably a semiconductor substrate, and The process of developing and patterning the resist film after exposure. Includes.

[0078] The present invention provides a method for reducing standing waves in a resist pattern, A process of forming a laminated film in which a resist underlayer film is formed by applying a resist underlayer film forming composition to a substrate containing a metal on its surface, preferably a semiconductor substrate, and then heating it in the presence of oxygen, wherein the resist underlayer film exists on the metal oxide film. A step of forming a resist film by coating the resist on the resist underlayer film and baking it. A step of exposing the resist underlayer film and the substrate coated with the resist, preferably a semiconductor substrate, and The process of developing and patterning the resist film after exposure. It may include.

[0079] The meanings of the terms used in the above explanation are as stated above. [Examples]

[0080] The present invention will now be specifically described 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] A solution of a lithography resist underlayer forming composition was prepared by adding 3.63 g of a solution (solid content 16.78% by weight) of the reaction product prepared by the method according to Synthesis Example 2 of WO2020 / 255984, to 0.12 g of tetramethoxymethyl glycoluryl (trade name: POWDER LINK [registered trademark] 1174, manufactured by Japan Scientific Industries, Ltd.) as a crosslinking agent, 0.006 g of pyridinium-p-toluenesulfonate, 0.01 g of Megafac R-30N (manufactured by DIC Corporation, trade name), 134.37 g of propylene glycol monomethyl ether, and 14.93 g of propylene glycol monomethyl ether acetate. The reaction product contains a structure represented by the following formula (A-2). [ka]

[0082] [Evaluation of the optical constants of copper oxide films] 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 (attenuation coefficient) of the obtained copper oxide film were measured at a wavelength of 365 nm (i-line wavelength) using a spectroscopic ellipsometer (M-2000D, JAWoolam). The results are shown in Table 1. [Table 1] From the results above, 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-reflective function that can suppress reflection (standing waves) from the underlying substrate, which is a cause of undesirable resist patterns in lithography processes using radiation such as i-rays. For this reason, 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 lithography resist underlayer film formation composition prepared in Preparation Example 1 was coated onto a silicon wafer using a spin coater to a thickness of approximately 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 were measured at a wavelength of 365 nm (i-line wavelength) using a spectroscopic ellipsometer (VUV-VASE, JAWoolam). The results are shown in Table 2. [Table 2] From the above results, the resist underlayer film forming composition obtained by Preparation Example 1 has appropriate n and k values ​​at 365 nm, and therefore has an anti-reflective function that can suppress reflection (standing waves) from the underlying substrate, which is a cause of undesirable resist patterns in lithography processes using radiation such as i-rays. For this reason, it is useful as a resist underlayer film.

[0084] [Evaluation of resist pattern shape] <Example 1> 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. Next, a commercially available i-line exposure positive resist was applied using a spin coater to a thickness of approximately 2 μm, and pre-baked on a hot plate at 90°C for 3 minutes to form a photoresist laminate. Then, the photoresist laminate was subjected to i-line exposure using a stepper (Nikon, NSR-2205i12D) through a pattern mask for resolution measurement. After exposure, it was post-baked at 90°C for 90 seconds, and developed with a 2.38% aqueous solution of tetramethylammonium hydroxide (TMAH) (product name: NMD-3, manufactured by Tokyo Ohka Co., Ltd.), which is a resist developer, to obtain a 0.8 μm 1:1 line-and-space resist pattern. Subsequently, the cross-sectional shape of this resist pattern was observed using a scanning electron microscope, and the degree of undulation due to standing waves in the resist pattern shape was evaluated.

[0085] <Example 2> The lithography resist underlayer film-forming composition prepared in Preparation Example 1 was applied to an 8-inch diameter copper 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 simultaneously form a copper oxide film (thickness approximately 10 nm) on the surface of the copper substrate and the lithography resist underlayer film-forming composition on top of it. Next, a general i-line resist was applied using a spin coater to a thickness of approximately 2 μm, and pre-baked on a hot plate at 90°C for 3 minutes to form a photoresist laminate. Then, the photoresist laminate was subjected to i-line exposure using a stepper (Nikon, 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 2.38% aqueous solution of tetramethylammonium hydroxide (TMAH) (product name: NMD-3, manufactured by Tokyo Ohka Co., Ltd.), a resist developer, to obtain a 0.8 μm 1:1 line-and-space resist pattern. Subsequently, the cross-sectional shape of this resist pattern was observed using a scanning electron microscope, and the degree of undulation due to standing waves in the resist pattern shape was evaluated.

[0086] <Example 3> A copper oxide film (thickness approximately 20 nm) was formed on the surface of an 8-inch diameter copper substrate by baking it on a hot plate at 150°C for 30 minutes. Next, the lithography resist underlayer film forming composition prepared in Preparation Example 1 was applied 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 the lithography resist underlayer film forming composition on top of the copper oxide film. Then, a general i-line resist was applied using a spin coater to a thickness of approximately 2 μm, and pre-baked 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, 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 2.38% aqueous solution of tetramethylammonium hydroxide (TMAH) (product name: NMD-3, manufactured by Tokyo Ohka Co., Ltd.), a resist developer, to obtain a 0.8 μm 1:1 line-and-space resist pattern. Subsequently, the cross-sectional shape of this resist pattern was observed using a scanning electron microscope, and the degree of undulation due to standing waves in the resist pattern shape was evaluated.

[0087] <Comparative Example 1> A commercially available positive-type resist for i-line exposure was applied to an 8-inch diameter copper substrate using a spin coater to a thickness of approximately 2 μm. The substrate was then pre-baked 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 NSR-2205i12D) through a pattern mask for resolution measurement. After exposure, the substrate was post-baked at 90°C for 90 seconds. This was then developed with a 2.38% aqueous solution of tetramethylammonium hydroxide (TMAH) (product name: NMD-3, Tokyo Ohka Co., Ltd.) to obtain a 0.8 μm 1:1 line-and-space resist pattern. Subsequently, the cross-sectional shape of this resist pattern was observed using a scanning electron microscope to evaluate the degree of undulation due to standing waves in the resist pattern shape.

[0088] The evaluation criteria for the resist pattern shape in Examples 1-3 and Comparative Example 1 were as follows: compared to Comparative Example 1, a large amount of standing wave undulation in the resist pattern shape was marked with "×", and a small amount with "○". The results are shown in Table 3 below. The thickness of the copper oxide film was measured by observing the cross-section of the substrate using a scanning electron microscope. [Table 3] From the results above, Examples 1 to 3 yielded resist pattern shapes with less undulation due to standing waves compared to Comparative Example 1. In other words, by using a copper oxide film, or a copper oxide film and a resist underlayer film simultaneously, it is possible to reduce reflection (standing waves) from the copper substrate during exposure in lithography, thereby suppressing the undesirable phenomenon of undulation in the resist pattern shape after development. [Industrial applicability]

[0089] According to the present invention, in the lithography process for semiconductor device manufacturing, by reducing the exposure reflectance from the substrate, standing waves (defects due to reflection) in the resist pattern can be reduced, and a good rectangular resist pattern can be obtained on the substrate.

Claims

1. A method for manufacturing a substrate with a resist pattern, A process of forming a laminated film in which a resist underlayer film is formed on a substrate containing a metal on its surface by applying a resist underlayer film forming composition, and then heating it in the presence of oxygen, A step of forming a resist film by coating the resist on the resist underlayer film and baking it. A step of exposing the resist underlayer film and the substrate coated with the resist, and The process of developing and patterning the resist film after exposure. A method for manufacturing a resist patterned substrate, wherein the resist underlayer film contains a heterocyclic compound, and the standing waves of the resist pattern are reduced.

2. The method for manufacturing a resist patterned substrate according to Claim 1, wherein the metal includes copper.

3. The method for manufacturing a resist patterned substrate according to Claim 1, wherein the resist underlayer film contains a compound represented by the following formula (I). [Chemistry 18] [In formula (I), A1 to A3 are each an alkylene group having 1 to 6 carbon atoms, which may be directly bonded or substituted. B1 to B3 each independently represent a direct bond, an ether bond, a thioether bond, or an ester bond. R4 to R12 each independently represent a hydrogen atom, a methyl group, or an ethyl group. Z1 to Z3 represent the following equation (II): 【Chemistry 19】 (In formula (II), Each of the n X 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, thioether bond, or ester bond, and n represents an integer from 0 to 4.

4. A method for manufacturing a semiconductor device, A process of forming a laminated film in which a resist underlayer film is formed on a semiconductor substrate containing a metal on its surface by applying a resist underlayer film forming composition, and then heating it in the presence of oxygen, wherein the resist underlayer film is present on the metal oxide film. A step of forming a resist film by coating the resist on the resist underlayer film and baking it. A step of exposing the resist underlayer film and the semiconductor substrate coated with the resist, and The process of developing and patterning the resist film after exposure. A method for manufacturing a semiconductor device, comprising a resist patterned substrate, wherein the resist underlayer film contains a heterocyclic compound, and the standing waves of the resist pattern are reduced.

5. A method for reducing standing waves in a resist pattern, A process of forming a laminated film in which a resist underlayer film is formed on a substrate containing metal on its surface or on a semiconductor substrate, and then heating it in the presence of oxygen, wherein the resist underlayer film is present on the metal oxide film. A step of forming a resist film by coating the resist on the resist underlayer film and baking it. A step of exposing the resist underlayer film and the substrate or semiconductor substrate coated with the resist, and The process of developing and patterning the resist film after exposure. A method for reducing standing waves in a resist pattern, wherein the resist underlayer film contains a heterocyclic compound.

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