Composition for forming protective film, protective film, method for manufacturing substrate, and method for manufacturing semiconductor device

Abstract

This composition for forming a protective film against a wet etching solution for semiconductors includes: component (A): a film-forming component; component (B): a compound selected from the group consisting of condensed tannin (b1) obtained by polymerizing a compound having a flavanol skeleton, a hydrolyzable tannin (b2) obtained by ester-bonding a sugar to an aromatic compound of gallic acid or ellagic acid, and a flavonoid (b3) derived from a compound having a flavanone skeleton structure; and component (C): a solvent.

Description

Composition for forming protective film, protective film, method for manufacturing substrate, and method for manufacturing semiconductor device

[0001] The present invention relates to a composition for forming a protective film, which is used in a lithography process in semiconductor manufacturing to form a protective film having excellent resistance to a semiconductor wet etching solution, and also to a method for manufacturing a substrate having a resist pattern using the composition for forming a protective film, and a method for manufacturing a semiconductor device.

[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 to be formed thereon, thereby forming a resist pattern of a desired shape. After the resist pattern is formed, the substrate is processed. Dry etching is the main process used for this, but wet etching may also be used depending on the type of substrate. Patent Document 1 discloses a resist underlayer film material that is resistant to alkaline hydrogen peroxide solution.

[0003] Japanese Patent Application Laid-Open No. 2018-173520

[0004] When a protective film for a semiconductor substrate is formed using a protective film-forming composition and the underlying substrate is processed by wet etching using the protective film as an etching mask, the protective film is required to have a good masking function against the semiconductor wet etching solution (i.e., to be able to protect the masked portion of the substrate). Furthermore, in the manufacturing process of a semiconductor device, if a large amount of sublimate is generated from the protective film, problems such as contamination of the baking tray and inside of the piping used during baking occur.

[0005] The present invention has been made in view of the above circumstances, and aims to provide a composition for forming a protective film that can form a protective film that has excellent resistance to a semiconductor wet etching solution while suppressing the generation of sublimated products. Another aim of the present invention is to provide a method for manufacturing a substrate with a protective film, a method for manufacturing a substrate with a resist pattern, and a method for manufacturing a semiconductor device using the composition for forming a protective film.

[0006] As a result of intensive research conducted by the inventors to solve the above-mentioned problems, they discovered that the above-mentioned problems can be solved by using a composition for forming a protective film containing a specific compound, and thus completed the present invention.

[0007] That is, the present invention encompasses the following aspects. [1] A composition for forming a protective film for a semiconductor wet etching solution, comprising: component (A): a film-forming component; component (B): a compound selected from the group consisting of condensed tannins (b1) formed by polymerization of a compound having a flavanol skeleton, hydrolyzable tannins (b2) formed by an ester bond between an aromatic compound such as gallic acid or ellagic acid and a sugar, and flavonoids (b3) derived from compounds having a flavanone skeleton structure; and component (C): a solvent. [2] The composition for forming a protective film according to [1], wherein component (B) is one or more compounds selected from the condensed tannins and the hydrolyzable tannins. [3] The composition for forming a protective film according to [1] or [2], wherein component (B) is the hydrolyzable tannin. [4] The composition for forming a protective film according to [3], wherein the hydrolyzable tannin is tannic acid represented by the following formula (I): (In the above formula (I), each G independently represents a hydrogen atom or a monovalent group represented by the following formula (II).) (In the above formula (II), n represents an integer of 0 to 3. However, the number of benzene rings in the above formula (I) is 4 or more and 17 or less. * represents a bond.) [5] The composition for forming a protective film according to any one of [1] to [4], further comprising a component (D): a curing catalyst. [6] The composition for forming a protective film according to any one of [1] to [5], wherein the content of the component (B) is 0.1 to 50 mass% relative to the mass of the solid content of the component (A). [7] A protective film against a semiconductor wet etching solution, which is a fired product of a coating film made of the composition for forming a protective film according to any one of [1] to [6]. [8] A method for producing a substrate with a protective film used in the production of a semiconductor, comprising a step of applying the composition for forming a protective film according to any one of [1] to [6] onto a semiconductor substrate and firing the composition to form a protective film. [9] A method for manufacturing a substrate with a resist pattern, which is used in manufacturing a semiconductor, comprising the steps of: applying the composition for forming a protective film according to any one of [1] to [6] onto a semiconductor substrate and baking the composition to form a protective film as a resist underlayer film; and forming a resist film on the protective film directly or via another layer, and then exposing and developing the resist film to form a resist pattern.

[10] A method for manufacturing a semiconductor device, which comprises the steps of forming a protective film using the composition for forming a protective film according to any one of [1] to [6] on a semiconductor substrate, on the surface of which an inorganic film may be formed, forming a resist pattern on the protective film, dry-etching the protective film using the resist pattern as a mask to expose the surface of the inorganic film or the semiconductor substrate, and wet-etching and cleaning the inorganic film or the semiconductor substrate using a semiconductor wet etching solution using the protective film after dry etching as a mask.

[0008] According to the present invention, there is provided a composition for forming a protective film, which is capable of forming a protective film having excellent resistance to a semiconductor wet etching solution while suppressing the generation of sublimated products. Furthermore, according to the present invention, there are provided a method for manufacturing a substrate with a protective film, a method for manufacturing a substrate with a resist pattern, and a method for manufacturing a semiconductor device using the composition for forming a protective film.

[0009] Fig. 1 is a cross-sectional view schematically showing a part of a semiconductor substrate used in a resistance test; Fig. 2 is a cross-sectional view schematically showing a part of a semiconductor substrate on which a protective film is formed; Fig. 3 is a cross-sectional view schematically showing a part of a semiconductor substrate after dry etching; and Fig. 4 is a cross-sectional view schematically showing a part of a semiconductor substrate after wet etching.

[0010] (Composition for forming a protective film) The composition for forming a protective film of the present invention is a composition for forming a protective film. The protective film is preferably a protective film that protects an inorganic film formed on a surface of a semiconductor substrate from wet etching. The composition for forming a protective film includes components (A), (B), and (C). Component (A) is a film-forming component. Component (B) is a compound selected from the group consisting of condensed tannins (b1) formed by polymerization of a compound having a flavanol skeleton, hydrolyzable tannins (b2) formed by ester bonding an aromatic compound of gallic acid or ellagic acid to a sugar, and flavonoids (b3) derived from compounds having a flavanone skeleton. Component (C) is a solvent.

[0011] The present inventors conducted extensive research to form a protective film having excellent resistance to semiconductor wet etching solutions. They discovered that adding an additive having an aromatic ring and an aromatic hydroxy group (e.g., gallic acid) to a protective film-forming composition can form a protective film having excellent resistance to semiconductor wet etching solutions. However, the present inventors discovered that adding the additive to a protective film-forming composition increases the amount of sublimates generated from the protective film. As a result of further research, they discovered that adding a specific component (B) to a protective film-forming composition, rather than simply adding an additive having an aromatic ring and an aromatic hydroxy group, can form a protective film having excellent resistance to semiconductor wet etching solutions while suppressing the amount of sublimates generated, thereby completing the present invention.

[0012] <Component (A)> Component (A) is a film-forming component. In this specification, the film-forming component refers to components other than component (B) and component (C) in the composition for forming a protective film.

[0013] The film-forming component includes, for example, an organic compound. The organic compound may be a low-molecular-weight compound or a high-molecular-weight compound (polymer). Examples of such organic compounds include the following compounds: a compound having a group represented by formula (1) at a side chain or terminal and having a weight average molecular weight of 800 or more in the protective film-forming composition described in WO 2017 / 191767; a compound represented by formula (1a) or formula (1b), a compound having a molecular weight of 300 or more but less than 800 and having a substituent represented by formula (2), or a compound having a weight average molecular weight of 300 or more but less than 800 in the protective film-forming composition described in WO 2018 / 052130; a resin (e.g., polyester, polyether, polyether ether ketone, novolac resin, maleimide resin, acrylic resin, and methacrylic resin) in the protective film-forming composition described in WO 2018 / 203464; a compound containing at least one pair of two adjacent hydroxyl groups in the molecule, or a polymer thereof, in the protective film-forming composition described in WO 2019 / 124474. - A compound containing at least one acetal structure in the molecule, or a polymer thereof, in the protective film-forming composition described in WO 2019 / 124475; - A ring-opening polymer (C) obtained by reacting a diepoxy compound (A) with a difunctional or higher proton-generating compound (B) in the protective film-forming composition described in WO 2020 / 090950; - A compound or polymer containing at least one acetal structure and one amide structure in the protective film-forming composition described in WO 2020 / 153278. The contents of these publications are incorporated herein by reference to the same extent as if expressly stated in their entirety.

[0014] The polymer is not particularly limited, but preferably includes a polymer having at least one of a partial structure represented by the following formula (1), a partial structure represented by the following formula (2), and a partial structure represented by the following formula (3) (hereinafter, sometimes referred to as "polymer (A)"). It is more preferable that polymer (A) has a partial structure represented by the following formula (1), a partial structure represented by the following formula (2), and a partial structure represented by the following formula (3). (In formula (1), X １ represents a divalent group represented by the following formula (1-1), (1-2), or (1-3): １ and Z ２ A each independently represents a direct bond or a divalent group represented by the following formula (1-4): １ , A ２ , A ３ , A ４ , A ５ and A ６ Each of Q independently represents a hydrogen atom, a methyl group, or an ethyl group. * represents a bond. １ represents a divalent organic group having an aromatic hydrocarbon ring or an aliphatic hydrocarbon ring. １１ , A １２ , A １３ , A １４ , A １５ and A １６ Each of n1 and n2 independently represents a hydrogen atom, a methyl group, or an ethyl group. Each of n1 and n2 independently represents 0 or 1. * represents a bond. In formula (3), R １１ represents an organic group having 1 to 30 carbon atoms. m1 and m2 each independently represent 0 or 1. * represents a bond. (In formulas (1-1) to (1-3), R １ ~R ５R each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may be interrupted by an oxygen atom or a sulfur atom, an alkenyl group having 2 to 10 carbon atoms which may be interrupted by an oxygen atom or a sulfur atom, an alkynyl group having 2 to 10 carbon atoms which may be interrupted by an oxygen atom or a sulfur atom, a benzyl group, or a phenyl group, and the phenyl group may be substituted with at least one monovalent 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, and an alkylthio group having 1 to 6 carbon atoms. １ and R ２ may be bonded to each other to form a ring having 3 to 6 carbon atoms. ３ and R ４ may be bonded to each other to form a ring having 3 to 6 carbon atoms. * represents a bond. *1 represents a bond bonded to a carbon atom. *2 represents a bond bonded to a nitrogen atom. (In formula (1-4), m1 is an integer of 1 to 4, m2 is 0 or 1, *3 represents a bond bonded to a nitrogen atom, and *4 represents a bond bonded to a carbon atom.)

[0015] R in formulas (1-1) to (1-3) １ ~R ５ Examples of the alkyl group having 1 to 10 carbon atoms which may be interrupted by an oxygen atom or a sulfur atom in the formula (I) include an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkoxyalkyl group having 2 to 10 carbon atoms, an alkoxyalkoxyalkyl group having 3 to 10 carbon atoms, an alkylthio group having 1 to 10 carbon atoms, and an alkylthioalkyl group having 2 to 10 carbon atoms. The alkyl group having 1 to 10 carbon atoms which may be interrupted by an oxygen atom or a sulfur atom may contain two or more oxygen atoms or sulfur atoms.

[0016] <<X １ >> X in formula (1) １ From the viewpoint of suitably obtaining the effects of the present invention, it is preferable that the compound represented by formula (1-3) is used.

[0017] The structure represented by the following (1A) in formula (1) is (In formula (1A), Z １ , Z２ and X １ respectively represent Z in formula (1). １ , Z ２ and X １ (The symbol * represents a bond.) For example, the following structures are given as examples. In the above structure, * represents a bond.

[0018] <<Q １ >> Q in formula (2) １ From the viewpoint of suitably obtaining the effects of the present invention, it is preferable that the compound be represented by any one of the following formulas (2-1) to (2-4). (In formulas (2-1) to (2-4), R ２１ ~R ２６ each independently represents a halogen atom, a hydroxy group, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkenyloxy group having 2 to 6 carbon atoms, an alkynyloxy group having 2 to 6 carbon atoms, an acyl group having 2 to 6 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, an arylcarbonyl group having 7 to 13 carbon atoms, or an aralkyl group having 7 to 13 carbon atoms. * represents a bond. In formula (2-1), n3 represents 0 or 1. When n3 is 0, n11 represents an integer of 0 to 4. When n3 is 1, n11 represents an integer of 0 to 6. R ２１ When is 2 or more, R is 2 or more ２１ may be the same or different. １ represents a single bond, an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or an alkylene group having 1 to 6 carbon atoms. n12 and n13 each independently represent an integer of 0 to 4. R ２２ When is 2 or more, R is 2 or more ２２ may be the same or different. ２３ When is 2 or more, R is 2 or more ２３ In formula (2-3), Y may be the same or different. １ and Y ２each independently represents a single bond or an alkylene group having 1 to 6 carbon atoms. n14 represents an integer of 0 to 4. R ２４ When is 2 or more, R is 2 or more ２４ may be the same or different. ２ represents a single bond, an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or an alkylene group having 1 to 6 carbon atoms. n15 and n16 each independently represent an integer of 0 to 4. R ２５ When is 2 or more, R is 2 or more ２５ may be the same or different. ２６ When is 2 or more, R is 2 or more ２６ may be the same or different.)

[0019] As used herein, examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms. As used herein, alkyl groups are not limited to linear ones, and may be branched or cyclic. Examples of linear or branched alkyl groups include methyl groups, ethyl groups, isopropyl groups, tert-butyl groups, and n-hexyl groups. Examples of cyclic alkyl groups (cycloalkyl groups) include cyclobutyl groups, cyclopentyl groups, and cyclohexyl groups. As used herein, examples of alkoxy groups include methoxy groups, ethoxy groups, n-pentyloxy groups, and isopropoxy groups. As used herein, examples of alkylthio groups include methylthio groups, ethylthio groups, n-pentylthio groups, and isopropylthio groups. As used herein, examples of alkenyl groups include ethenyl, 1-propenyl, 2-propenyl, 1-methyl-1-ethenyl, 1-butenyl, 2-butenyl, 3-butenyl, 2-methyl-1-propenyl, and 2-methyl-2-propenyl groups. As used herein, examples of alkynyl groups include groups in which the double bond of the alkenyl groups listed above for "alkenyl groups" is replaced with a triple bond. As used herein, examples of alkenyloxy groups include vinyloxy, 1-propenyloxy, 2-n-propenyloxy (allyloxy), 1-n-butenyloxy, and prenyloxy groups. As used herein, examples of alkynyloxy groups include 2-propynyloxy, 1-methyl-2-propynyloxy, 2-methyl-2-propynyloxy, 2-butynyloxy, and 3-butynyloxy groups. As used herein, examples of acyl groups include acetyl groups and propionyl groups. As used herein, examples of aryloxy groups include phenoxy groups and naphthyloxy groups. As used herein, examples of arylcarbonyl groups include phenylcarbonyl groups. As used herein, examples of aralkyl groups include benzyl groups and phenethyl groups.In this specification, examples of the alkylene group include a methylene group, an ethylene group, a 1,3-propylene group, a 2,2-propylene group, a 1-methylethylene group, a 1,4-butylene group, a 1-ethylethylene group, a 1-methylpropylene group, a 2-methylpropylene group, a 1,5-pentylene group, a 1-methylbutylene group, a 2-methylbutylene group, a 1,1-dimethylpropylene group, a 1,2-dimethylpropylene group, a 1-ethylpropylene group, a 2-ethylpropylene group, a 1,6-hexylene group, a 1,4-cyclohexylene group, a 1,8-octylene group, a 2-ethyloctylene group, a 1,9-nonylene group, and a 1,10-decylene group.

[0020] The structure represented by the following (2A) in formula (2) is (In formula (2A), Q １ , n1 and n2 are respectively Q in formula (2) １ , n1 and n2 are the same. * represents a bond.) For example, the following structures can be mentioned. In the above structure, * represents a bond.

[0021] R in formula (3) １１ The organic group having 1 to 30 carbon atoms may or may not have an aromatic ring. Examples of the aromatic ring include an aromatic hydrocarbon ring and an aromatic heterocyclic ring. １１ The organic group having 1 to 30 carbon atoms may have an aliphatic ring or may not have an aliphatic ring. １１ The organic group having 1 to 30 carbon atoms may or may not have an unsaturated bond.

[0022] R in formula (3) １１ Examples of the organic group having 1 to 30 carbon atoms include an alkylene group having 1 to 10 carbon atoms which may be interrupted by an oxygen atom or a sulfur atom. The alkylene group having 1 to 10 carbon atoms which may be interrupted by an oxygen atom or a sulfur atom may contain two or more oxygen atoms or sulfur atoms.

[0023] Examples of the partial structure represented by formula (3) include the following structures: (In the formula, * represents a bond.)

[0024] From the viewpoint of suitably achieving the effects of the present invention, the polymer (A) preferably has at least one of a repeating unit represented by the following formula (A) and a repeating unit represented by the following formula (B). (In formula (A), X １ , Z １ , Z ２ , A １ , A ２ , A ３ , A ４ , A ５ and A ６ are X in formula (1), respectively. １ , Z １ , Z ２ , A １ , A ２ , A ３ , A ４ , A ５ and A ６ It is the same as R １１ , m1 and m2 are R in formula (3), １１ , m1 and m2 are the same as those in formula (B). １ , A １１ , A １２ , A １３ , A １４ , A １５ , A １６ , n1 and n2 are respectively Q in formula (2) １ , A １１ , A １２ , A １３ , A １４ , A １５ , A １６ , n1 and n2. １１ , m1 and m2 are R in formula (3), １１ , m1 and m2 are the same.)

[0025] In the polymer (A), the molar ratio (M1:M2) of the partial structure (M1) represented by formula (1) to the partial structure (M2) represented by formula (2) is not particularly limited, but is preferably 95:5 to 10:90, more preferably 95:5 to 20:80, and particularly preferably 95:5 to 40:60.

[0026] In the polymer (A), the molar ratio [(M1+M2):M3] of the total of the partial structure (M1) represented by formula (1) and the partial structure (M2) represented by formula (2) to the partial structure represented by formula (3) is not particularly limited, but is preferably 80:20 to 20:80, more preferably 70:30 to 30:70, and particularly preferably 60:40 to 40:60.

[0027] In the polymer (A), the molar ratio (MA:MB) of the repeating unit (MA) represented by formula (A) to the repeating unit (MB) represented by formula (B) is not particularly limited, but is preferably 95:5 to 10:90, more preferably 95:5 to 20:80, and particularly preferably 95:5 to 40:60.

[0028] The molar ratio of the total of the repeating units (MA) represented by formula (A) and the repeating units (MB) represented by formula (B) to all repeating units of the polymer (A) is not particularly limited, but is preferably 70 mol% or more, more preferably 80 mol% or more, and particularly preferably 90 mol% or more. The upper limit is not particularly limited, but is preferably 100 mol% or less.

[0029] Examples of the polymer (A) include the following polymers (1a) to (1o).

[0030] <<Method for Producing Polymer>> An example of a method for producing polymer (A) is not particularly limited, and includes, for example, a method of reacting at least one of a diepoxy compound represented by the following formula (A1) and a diepoxy compound represented by the following formula (A2) with a dicarboxylic acid, monocarboxylic acid, or diol represented by the following formula (A3). For example, at least one of a diepoxy compound represented by the following formula (A1) and a diepoxy compound represented by the following formula (A2) with a dicarboxylic acid, monocarboxylic acid, or diol represented by the following formula (A3) is dissolved in an organic solvent in an appropriate molar ratio. Then, a polymer is obtained by polymerization in the presence of a catalyst that activates the epoxy group. Note that, when producing polymer (A), a diepoxy compound other than the diepoxy compound represented by formula (A1) and the diepoxy compound represented by formula (A2) may be used in combination. Furthermore, when producing the polymer, a dicarboxylic acid, monocarboxylic acid, or diol other than the dicarboxylic acid, monocarboxylic acid, or diol represented by formula (A3) may be used in combination.

[0031] Examples of catalysts that activate epoxy groups include quaternary phosphonium salts such as tetrabutylphosphonium bromide and ethyltriphenylphosphonium bromide, and quaternary ammonium salts such as benzyltriethylammonium chloride. The amount of catalyst used can be selected appropriately from the range of 0.1 to 10% by mass based on the total mass of the polymer raw materials used in the reaction. Optimal conditions for the temperature and time of the polymerization reaction can be selected, for example, from the ranges of 80 to 160°C and 2 to 50 hours.

[0032] (In formula (A1), X １ , Z １ , Z ２ , A １ , A ２ , A ３ , A ４ , A ５ and A ６ are X in formula (1), respectively. １ , Z １ , Z ２ , A １ , A ２, A ３ , A ４ , A ５ and A ６ is the same as

[0033] (In formula (A2), Q １ , A １１ , A １２ , A １３ , A １４ , A １５ , A １６、 n1 and n2 are respectively Q in formula (2) １ , A １１ , A １２ , A １３ , A １４ , A １５ , A １６、 Same as n1 and n2.)

[0034] (In formula (A3), R １１ , m1 and m2 are R in formula (3), １１ , m1 and m2 are the same.)

[0035] Examples of the diepoxy compound represented by formula (A1) include the following diepoxy compounds.

[0036] Examples of the diepoxy compound represented by formula (A2) include the following diepoxy compounds.

[0037] Examples of the dicarboxylic acid, monocarboxylic acid, or diol represented by formula (A3) include the following compounds.

[0038] As the polymer, in addition to the above-mentioned polymer (A), acrylic resin, epoxy resin, novolac resin, etc. can also be used.

[0039] The weight average molecular weight Mw of the polymer (for example, polymer (A)) is not particularly limited, but is preferably 1,000 to 50,000, more preferably 1,500 to 30,000, and particularly preferably 2,000 to 10,000. In the present invention, the weight average molecular weight Mw is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0040] The content of the polymer (e.g., polymer (A)) in the protective film-forming composition is not particularly limited, but is preferably 50% by mass to 100% by mass, more preferably 75% by mass to 100% by mass, and particularly preferably 90% by mass to 100% by mass, based on the film-forming components.

[0041] <Component (B)> Component (B) is a compound selected from the group consisting of condensed tannins (b1) formed by polymerization of compounds having a flavanol skeleton, hydrolyzable tannins (b2) formed by ester bonding of an aromatic compound such as gallic acid or ellagic acid to a sugar, and flavonoids (b3) derived from compounds having a flavanone skeleton structure.

[0042] <<(b1)>> (b1) is a condensed tannin formed by polymerization of a compound having a flavanol skeleton. In this specification, "tannin" refers to a water-soluble compound derived from a plant that reacts with proteins, alkaloids, and metal ions to form a weakly soluble salt by binding tightly. Tannins are ubiquitous in the plant kingdom and are aromatic compounds with many phenolic hydroxy groups. Tannins according to this embodiment include condensed tannins and hydrolyzable tannins. The condensed tannin according to this embodiment is a compound formed by polymerization of a compound having a flavanol skeleton represented by the following formula (p):

[0043]

[0044] <<(b2)>> (b2) is a hydrolyzable tannin formed by an ester bond between an aromatic compound of gallic acid or ellagic acid and a sugar. The hydrolyzable tannin according to this embodiment is a compound formed by an ester bond between an aromatic compound of gallic acid or ellagic acid represented by the following formula (q) and a sugar such as glucose represented by the following formula (r):

[0045]

[0046]

[0047] A preferred embodiment of the hydrolyzable tannin is, for example, tannic acid represented by the following formula (I).

[0048] (In the above formula (I), each G independently represents a hydrogen atom or a monovalent group represented by the following formula (II).) (In the above formula (II), n represents an integer of 0 to 3. However, the number of benzene rings in the above formula (I) is 4 to 17. * represents a bond.)

[0049] In order to preferably obtain the effects of the present invention, n in formula (II) is preferably 0 to 2, and more preferably 1 or 2.

[0050] An example of the structure of tannic acid represented by the above formula (I) is shown in the following formula (III).

[0051] The formula (III) is a compound in which all Gs in the formula (I) are monovalent groups represented by the formula (II), and all n's in the formula (II) are 1.

[0052] <<(b3)>> (b3) is a flavonoid derived from a compound having a flavanone skeleton structure. The flavonoid according to this embodiment refers to a compound biosynthesized by subjecting flavanone, a type of flavonoid, to various modifications. Examples of the flavonoid according to this embodiment include compounds derived from a compound having a flavanone skeleton structure represented by the following formula (s):

[0053]

[0054] Preferred embodiments of the flavonoid include, for example, flavonoids represented by the following formula (s1) or (s2).

[0055]

[0056] From the viewpoint of suitably achieving the effects of the present invention, component (B) is preferably (b2), and more preferably tannic acid represented by formula (I).

[0057] From the viewpoint of suitably obtaining the effects of the present invention, the content of component (B) is, for example, preferably 0.1 to 50 mass %, more preferably 1 to 20 mass %, and even more preferably 5 to 15 mass %, relative to component (A).

[0058] The weight average molecular weight Mw of component (B) is not particularly limited, but is, for example, preferably 700 to 2500, more preferably 1000 to 2000, and even more preferably 1500 to 1900. In the present invention, the weight average molecular weight Mw is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0059] <Component (C)> Component (C) is a solvent. The composition for forming a protective film of the present invention can be prepared by dissolving the above-mentioned components in a solvent, preferably an organic solvent, and is used in the form of a homogeneous solution.

[0060] As the organic solvent for the composition for forming a protective film according to the present invention, any organic solvent can be used without particular limitation as long as it can dissolve solid components such as component (A), component (B), and other optional solid components. In particular, since the composition for forming a protective film according to the present invention is used in the state of a homogeneous solution, in consideration of its coating performance, it is recommended to use an organic solvent that is generally used in lithography processes in combination with the composition.

[0061] Examples of organic solvents include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolve acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, propylene glycol propyl ether acetate, toluene, xylene, methyl ethyl ketone, and methyl isobutyl Examples of suitable solvents include ketones, cyclopentanone, cyclohexanone, cycloheptanone, 4-methyl-2-pentanol, ethyl ethoxyacetate, 2-hydroxyethyl acetate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl pyruvate, ethyl acetate, butyl acetate, 2-heptanone, methoxycyclopentane, anisole, γ-butyrolactone, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide. These solvents may be used alone or in combination of two or more.

[0062] Among these solvents, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, cyclohexanone, etc. are preferred, with propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate being particularly preferred.

[0063] The solids content of the protective film-forming composition according to the present invention is typically 0.1 to 70% by mass, preferably 0.1 to 60% by mass. The solids content is the content of all components excluding the solvent from the protective film-forming composition. The proportion of component (A) in the solids content is preferably 1 to 99.9% by mass, more preferably 50 to 99.9% by mass, even more preferably 50 to 95% by mass, and particularly preferably 50 to 90% by mass.

[0064] <Component (D)> Component (D) is a curing catalyst. The curing catalyst optionally contained in the protective film-forming composition may be either a thermal acid generator or a photoacid generator, but it is preferable to use a thermal acid generator.

[0065] Examples of the thermal acid generator include sulfonic acid compounds and carboxylic acid compounds such as p-toluenesulfonic acid, trifluoromethanesulfonic acid, pyridinium p-toluenesulfonate (pyridinium p-toluenesulfonic acid), pyridinium phenolsulfonic acid, pyridinium p-hydroxybenzenesulfonic acid (pyridinium p-phenolsulfonate salt), pyridinium trifluoromethanesulfonic acid, salicylic acid, camphorsulfonic acid, 5-sulfosalicylic acid, 4-chlorobenzenesulfonic acid, 4-hydroxybenzenesulfonic acid, benzenedisulfonic acid, 1-naphthalenesulfonic acid, citric acid, benzoic acid, and hydroxybenzoic acid.

[0066] Examples of the photoacid generator include an onium salt compound, a sulfonimide compound, and a disulfonyldiazomethane compound.

[0067] Examples of the onium salt compound include iodonium salt compounds such as diphenyliodonium hexafluorophosphate, diphenyliodonium trifluoromethanesulfonate, diphenyliodonium nonafluoro-normal butanesulfonate, diphenyliodonium perfluoro-normal octanesulfonate, diphenyliodonium camphorsulfonate, bis(4-tert-butylphenyl)iodonium camphorsulfonate, and bis(4-tert-butylphenyl)iodonium trifluoromethanesulfonate; and sulfonium salt compounds such as triphenylsulfonium hexafluoroantimonate, triphenylsulfonium nonafluoro-normal butanesulfonate, triphenylsulfonium camphorsulfonate, and triphenylsulfonium trifluoromethanesulfonate.

[0068] Examples of sulfonimide compounds include N-(trifluoromethanesulfonyloxy)succinimide, N-(nonafluoronormalbutanesulfonyloxy)succinimide, N-(camphorsulfonyloxy)succinimide, and N-(trifluoromethanesulfonyloxy)naphthalimide.

[0069] Examples of the disulfonyldiazomethane compound include bis(trifluoromethylsulfonyl)diazomethane, bis(cyclohexylsulfonyl)diazomethane, bis(phenylsulfonyl)diazomethane, bis(p-toluenesulfonyl)diazomethane, bis(2,4-dimethylbenzenesulfonyl)diazomethane, and methylsulfonyl-p-toluenesulfonyldiazomethane.

[0070] The curing catalyst may be used alone or in combination of two or more.

[0071] When a curing catalyst is used, the content of the curing catalyst relative to component (A) is, for example, 0.1 to 50% by mass, and preferably 1 to 30% by mass.

[0072] (Protective film, method for manufacturing a substrate with a protective film, method for manufacturing a substrate with a resist pattern, and method for manufacturing a semiconductor device) The protective film of the present invention is a fired product of a coating film made of a composition for forming a protective film. The method for manufacturing a substrate with a protective film of the present invention includes a step of applying the composition for forming a protective film of the present invention to a semiconductor substrate having a step and firing the composition to form a protective film.

[0073] The method for producing a substrate having a resist pattern of the present invention comprises the following steps (1) and (2): Step (1): A step of applying the composition for forming a protective film of the present invention onto a semiconductor substrate and baking it to form a protective film as a resist underlayer film; Step (2): A step of forming a resist film on the protective film directly or via another layer, followed by exposure and development to form a resist pattern.

[0074] The method for manufacturing a semiconductor device of the present invention includes the following steps (A) to (D): step (A): forming a protective film on a semiconductor substrate having an inorganic film formed on its surface using the protective film-forming composition of the present invention; step (B): forming a resist pattern on the protective film directly or via another layer; step (C): dry-etching the protective film using the resist pattern as a mask to expose the surface of the inorganic film; and step (D): wet-etching the inorganic film using a semiconductor wet etching solution using the protective film after dry etching as a mask.

[0075] Examples of semiconductor substrates to which the protective film-forming composition (resist underlayer film-forming composition) of the present invention can be applied include silicon wafers, germanium wafers, and compound semiconductor wafers such as gallium arsenide, indium phosphide, gallium nitride, indium nitride, and aluminum nitride.

[0076] When a semiconductor substrate having an inorganic film formed on its surface is used, the inorganic film can be formed by, for example, ALD (atomic layer deposition), CVD (chemical vapor deposition), reactive sputtering, ion plating, vacuum deposition, or spin coating (spin-on glass: SOG). Examples of the inorganic film include polysilicon films, silicon oxide films, silicon nitride films, silicon oxynitride films, BPSG (Boro-Phospho Silicate Glass) films, titanium nitride films, titanium oxynitride films, tungsten nitride films, gallium nitride films, and gallium arsenide films. The semiconductor substrate may be a stepped substrate having vias (holes), trenches (grooves), and the like formed therein. For example, a via has a substantially circular shape when viewed from above, with a diameter of, for example, 0.5 nm to 50 nm and a depth of, for example, 50 nm to 500 nm, and a trench has, for example, a groove (recess in a substrate) with a width of 0.5 nm to 50 nm and a depth of 50 nm to 500 nm. The protective film-forming composition (resist underlayer film-forming composition) of the present invention can fill even uneven substrates such as those described above without defects such as voids (gaps). The absence of defects such as voids is an important characteristic for subsequent processes in semiconductor manufacturing (wet etching / dry etching of a semiconductor substrate, resist pattern formation).

[0077] The protective film-forming composition of the present invention is applied to such a semiconductor substrate using an appropriate application method such as a spinner or coater. A protective film is then formed by baking using a heating means such as a hot plate. Baking conditions are appropriately selected from a baking temperature of 100°C to 400°C and a baking time of 0.3 to 60 minutes. Preferably, the baking temperature is 120°C to 350°C, the baking time is 0.5 to 30 minutes, and more preferably, the baking temperature is 150°C to 300°C, and the baking time is 0.8 to 10 minutes. The thickness of the formed protective film is, for example, 0.001 μm to 10 μm, preferably 0.002 μm to 1 μm, and more preferably 0.005 μm to 0.5 μm. If the baking temperature is lower than the above range, crosslinking may be insufficient, and the formed protective film may not be resistant to resist solvents or basic hydrogen peroxide aqueous solutions. On the other hand, if the baking temperature is higher than the above range, the protective film may be thermally decomposed.

[0078] A resist film is formed on the protective film formed as described above, either directly or via another layer, followed by exposure and development to form a resist pattern. Exposure is performed through a mask (reticle) for forming a predetermined pattern, and for example, i-line, KrF excimer laser, ArF excimer laser, EUV (extreme ultraviolet), or EB (electron beam) is used. An alkaline developer is used for development, with the development temperature selected from 5°C to 50°C and the development time selected from 10 seconds to 300 seconds. Examples of alkaline developers that can be used include aqueous solutions of inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, and aqueous ammonia; primary amines such as ethylamine and n-propylamine; secondary amines such as diethylamine and di-n-butylamine; tertiary amines such as triethylamine and methyldiethylamine; alcohol amines such as dimethylethanolamine and triethanolamine; quaternary ammonium salts such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, and choline; and cyclic amines such as pyrrole and piperidine. Furthermore, an appropriate amount of an alcohol such as isopropyl alcohol or a nonionic surfactant can be added to the aqueous alkali solution. Among these, preferred developers are quaternary ammonium salts, more preferably tetramethylammonium hydroxide and choline. Furthermore, surfactants can be added to these developers. A method can also be used in which development is carried out with an organic solvent such as butyl acetate instead of an alkaline developer, and the parts of the photoresist where the alkaline dissolution rate is not improved are developed.

[0079] Next, the protective film is dry-etched using the formed resist pattern as a mask, to expose the surface of the inorganic film if the inorganic film is formed on the surface of the semiconductor substrate used, or to expose the surface of the semiconductor substrate if the inorganic film is not formed on the surface of the semiconductor substrate used.

[0080] Furthermore, the protective film after dry etching (and the resist pattern, if any, remaining on the protective film) is used as a mask to perform wet etching using a semiconductor wet etching solution, thereby forming a desired pattern.

[0081] As the wet etching solution for semiconductors, a general chemical solution for etching semiconductor wafers can be used, and for example, either an acidic substance or a basic substance can be used.

[0082] Examples of substances that exhibit acidity include hydrogen peroxide, hydrofluoric acid, ammonium fluoride, acidic ammonium fluoride, ammonium hydrogen fluoride, buffered hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, and mixtures thereof.

[0083] Examples of substances that exhibit basicity include basic hydrogen peroxide solution, which is obtained by mixing ammonia, sodium hydroxide, potassium hydroxide, sodium cyanide, potassium cyanide, or an organic amine such as triethanolamine with hydrogen peroxide solution to make the pH basic. A specific example is SC-1 (ammonia-hydrogen peroxide solution). Other substances that can make the pH basic, such as a solution obtained by mixing urea with hydrogen peroxide solution and heating to cause thermal decomposition of the urea to generate ammonia, which ultimately makes the pH basic, can also be used as a wet etching chemical.

[0084] Among these, acidic hydrogen peroxide solution or basic hydrogen peroxide solution is preferred.

[0085] These chemical solutions may contain additives such as surfactants.

[0086] The temperature at which the semiconductor wet etching solution is used is preferably 25° C. to 90° C., and more preferably 40° C. to 80° C. The wet etching time is preferably 0.5 to 30 minutes, and more preferably 1 to 20 minutes.

[0087] The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples.

[0088] The weight average molecular weights of the polymers shown in the examples below in this specification are the results of measurement by gel permeation chromatography (hereinafter abbreviated as GPC). A GPC device manufactured by Tosoh Corporation was used for the measurement, and the measurement conditions were as follows: GPC column: Shodex (registered trademark) KF803L, Shodex (registered trademark) KF802, Shodex (registered trademark) KF801 (manufactured by Resonac Co., Ltd.) Column temperature: 40°C Solvent: tetrahydrofuran (THF) Flow rate: 1.0 ml / min Standard sample: polystyrene (manufactured by Tosoh Corporation)

[0089] Synthesis Example 1 90.0 g of diglycidyl methylisocyanurate (product name: MeDGIC, manufactured by Shikoku Chemical Industry Co., Ltd., 29.9 wt% propylene glycol monomethyl ether solution), 17.09 g of succinic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), and 2.73 g of tetrabutylphosphonium bromide (manufactured by Hokko Chemical Industry Co., Ltd.) were added to a reaction flask, and the mixture was heated and stirred at 100° C. for 16 hours under a nitrogen atmosphere. The resulting reaction product corresponded to the following formula (1o), and had a weight average molecular weight Mw of 954 as measured by GPC in terms of polystyrene.

[0090]

[0091] Example 1 4.78 g of a solution (solid content 16.5% by mass) of a reaction product obtained by the method described in Synthesis Example 12 of WO 2020 / 026834 (corresponding to the following formula (1n) and a copolymer having a weight average molecular weight of 4500 as measured by GPC relative to polystyrene standards), 0.030 g of pyridinium trifluoromethanesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.040 g of tannic acid (a compound represented by the following formula (I), manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.), 0.00079 g of a surfactant (product name: Megafac (registered trademark) R-40, manufactured by DIC Corporation), 1.9 g of propylene glycol monomethyl ether acetate, and 13.2 g of propylene glycol monomethyl ether were added to form a solution. The solution was filtered using a polyethylene microfilter having a pore size of 0.02 μm to prepare a composition for forming a protective film. (In the above formula (I), each G independently represents a hydrogen atom or a monovalent group represented by the following formula (II).) (In the above formula (II), n represents an integer of 0 to 3. However, the number of benzene rings in the above formula (I) is 4 to 17. * represents a bond.) An example of the structure of tannic acid represented by the above formula (I) is shown in the following formula (III). The formula (III) is a compound in which all Gs in the formula (I) are monovalent groups represented by the formula (II), and all n's in the formula (II) are 1.

[0092] Example 2 4.57 g of a solution (solid content 16.5% by mass) of the reaction product obtained by the method described in Synthesis Example 12 of WO 2020 / 026834 (corresponding to the above formula (1n) and a copolymer having a weight average molecular weight of 4500 measured in polystyrene equivalent by GPC), 0.028 g of pyridinium trifluoromethanesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.076 g of tannic acid (compound represented by the above formula (I), manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.), 0.00076 g of a surfactant (product name: Megafac (registered trademark) R-40, manufactured by DIC Corporation), 1.9 g of propylene glycol monomethyl ether acetate, and 13.4 g of propylene glycol monomethyl ether were added to form a solution. The solution was filtered using a polyethylene microfilter having a pore size of 0.02 μm, to prepare a composition for forming a protective film.

[0093] Example 3 0.030 g of pyridinium trifluoromethanesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.040 g of tannic acid (compound represented by formula (I) above, manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.), 0.00079 g of a surfactant (product name: Megafac (registered trademark) R-40, manufactured by DIC Corporation), 1.9 g of propylene glycol monomethyl ether acetate, and 13.2 g of propylene glycol monomethyl ether were added to 4.84 g of a solution containing the reaction product obtained in Synthesis Example 1 (solid content: 16.3 mass%) to form a solution. The solution was filtered using a polyethylene microfilter having a pore size of 0.02 μm, to prepare a composition for forming a protective film.

[0094] Example 4 To 4.63 g of a solution containing the reaction product obtained in Synthesis Example 1 (solid content: 16.3% by mass), 0.028 g of pyridinium trifluoromethanesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.076 g of tannic acid (compound represented by formula (I) above, manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.), 0.00076 g of a surfactant (product name: Megafac (registered trademark) R-40, manufactured by DIC Corporation), 1.9 g of propylene glycol monomethyl ether acetate, and 13.3 g of propylene glycol monomethyl ether were added to obtain a solution. The solution was filtered using a polyethylene microfilter having a pore size of 0.02 μm, thereby preparing a composition for forming a protective film.

[0095] Comparative Example 1 To 5.01 g of a solution (solids content: 16.5% by mass) of the reaction product (corresponding to the above formula (1n) and a copolymer having a weight average molecular weight of 4,500 as measured by GPC relative to polystyrene standards) obtained by the method described in Synthesis Example 12 of WO 2020 / 026834, 0.031 g of pyridinium trifluoromethanesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.00083 g of a surfactant (product name: Megafac (registered trademark) R-40, manufactured by DIC Corporation), 13.0 g of propylene glycol monomethyl ether, and 1.91 g of propylene glycol monomethyl ether acetate were added to obtain a solution. The solution was filtered using a polyethylene microfilter having a pore size of 0.02 μm, to prepare a composition for forming a protective film.

[0096] Comparative Example 2 To 4.78 g of a solution (solids content: 16.5% by mass) of the reaction product obtained by the method described in Synthesis Example 12 of WO 2020 / 026834 (corresponding to the above formula (1n) and a copolymer having a weight average molecular weight of 4,500 as measured by GPC relative to polystyrene standards), 0.030 g of pyridinium trifluoromethanesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.040 g of gallic acid hydrate (a hydrate of the compound represented by the following formula (3), manufactured by Tokyo Chemical Industry Co., Ltd.), 0.00079 g of a surfactant (product name: Megafac (registered trademark) R-40, manufactured by DIC Corporation), 13.2 g of propylene glycol monomethyl ether, and 1.9 g of propylene glycol monomethyl ether acetate were added to obtain a solution. The solution was filtered using a polyethylene microfilter having a pore size of 0.02 μm to prepare a composition for forming a protective film.

[0097] Comparative Example 3 4.78 g of a solution (solid content: 16.5% by mass) of the reaction product obtained by the method described in Synthesis Example 12 of WO2020 / 026834 (corresponding to the above formula (1n), a copolymer having a weight average molecular weight measured in polystyrene equivalent by GPC of 4500), pyridinium trifluoromethanesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.) 0.030 g, (2,3,4-trihydroxyphenyl) (3,4,5-trihydroxyphenyl) methanone (a compound represented by the following formula (2), also known as 2,3,3',4,4',5'-hexahydroxybenzophenone, exifone, or HHBP, manufactured by Tokyo Chemical Industry Co., Ltd.) 0.040 g, a surfactant (product name: Megafac (registered trademark) R-40, manufactured by DIC Corporation) 0.00079 g, propylene glycol monomethyl ether acetate 1.9 g, and propylene glycol monomethyl ether 13.2 g were added to obtain a solution. The solution was filtered using a polyethylene microfilter with a pore size of 0.02 μm to prepare a composition for forming a protective film.

[0098] Comparative Example 4 4.57 g of a solution (solids content: 16.5% by mass) of the reaction product obtained by the method described in Synthesis Example 12 of WO 2020 / 026834 (corresponding to the above formula (1n), a copolymer having a weight average molecular weight of 4500 as measured by GPC relative to polystyrene standards), 0.028 g of pyridinium trifluoromethanesulfonate (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.076 g of HHBP (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.00076 g of a surfactant (product name: Megafac (registered trademark) R-40, manufactured by DIC Corporation), 1.91 g of propylene glycol monomethyl ether acetate, and 13.4 g of propylene glycol monomethyl ether were added to obtain a solution. The solution was filtered using a polyethylene microfilter having a pore size of 0.02 μm, to prepare a composition for forming a protective film.

[0099] (Formation of Coating Film) [Resistance Test to Basic Hydrogen Peroxide Aqueous Solution] Protective films (coating films) were formed using each of the protective film-forming compositions prepared in Examples 1 to 4 and Comparative Examples 1 to 4, and a resistance test to basic hydrogen peroxide aqueous solution was performed. An outline of the resistance test is shown in FIGS. 1A to 1D. As shown in FIG. 1A, a silicon substrate 1 having a 5-nm-thick titanium nitride (TiN) film formed on its surface and having a step (width 37 nm, depth 240 nm) was used as the semiconductor substrate. FIG. 1A shows a portion of the silicon substrate, and multiple steps are provided. Next, as shown in FIG. 1B, each of the protective film-forming compositions prepared in Examples 1 to 4 and Comparative Examples 1 to 4 was applied to the silicon substrate 1, and heated at 220°C for 60 seconds to form a coating film (protective film 2). Next, as shown in FIG. 1C, the formed protective film 2 was etched using a dry etching apparatus (RIE-200NL, manufactured by Samco Inc.) using N ２ / O ２ Mixed gas (N ２ / O ２The protective film 2 was dry-etched for 60 seconds using a 200 / 10 volume ratio solution. The protective film 2 was dry-etched so that the TiN on the wall surface within the step was exposed. Next, a basic hydrogen peroxide solution was prepared by mixing 20 mL of a 28% by mass ammonia solution, 80 mL of a 33% by mass hydrogen peroxide solution, and 400 mL of ultrapure water. The dry-etched silicon substrate 1 was then immersed in the basic hydrogen peroxide solution heated to 60°C for 100 seconds for wet etching. The protective film 2 was then rinsed with water and dried. The state of the protective film 2 after drying was observed using a field-emission scanning electron microscope (Regulus® 8240) manufactured by Hitachi High-Technologies Corporation. As shown in Figure 1D, the wet etching had removed the TiN to a position deeper within the step than the protective film. The results of the resistance test to the basic hydrogen peroxide solution are shown in Table 1. In Table 1, "○" indicates a state in which no peeling was observed in the protective film after immersion, as in Comparative Example 3, and "×" indicates a worsened state in which peeling was observed in part or all of the protective film after immersion, compared to Comparative Example 3.

[0100]

[0101] [Optical Parameter Test] The protective film-forming compositions prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were each applied to a silicon wafer using a spinner. The coating was baked on a hot plate at 220°C for 1 minute to form a resist underlayer film (film thickness 50 nm). The n value (refractive index) and k value (extinction coefficient or absorption coefficient) of these films were measured at wavelengths of 193 nm and 248 nm using a spectroscopic ellipsometer (J.A. Woollam, VUV-VASE VU-302). The results are shown in Table 2.

[0102]

[0103] [Measurement of Sublimation Amount] Measurement of the amount of sublimation was carried out using the sublimation amount measurement device described in International Publication No. 2007 / 111147. The protective film-forming compositions prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were applied to a 4-inch diameter silicon wafer substrate using a spin coater at 1500 rpm for 60 seconds. The wafer coated with the protective film-forming composition was placed in the sublimation measurement device, which was equipped with a hot plate adjusted to 220°C, and baked for 60 seconds. The sublimation product was collected in a QCM (Quartz Crystal Microbalance) sensor, i.e., a quartz crystal microbalance sensor with electrodes. The QCM sensor is capable of measuring minute mass changes by utilizing the property that when sublimation product adheres to the surface (electrode) of a quartz crystal microbalance sensor, the frequency of the quartz crystal microbalance sensor changes (decreases) depending on the mass of the sublimation product.

[0104] The detailed measurement procedure is as follows: The hot plate of the sublimation amount measuring device was heated to 220°C, and the pump flow rate was set to 1 m ３ The flow rate was set to 1 / s and the device was left to stabilize for the first 60 seconds. Immediately thereafter, the wafer coated with the protective film-forming composition was quickly placed on the hot plate through the slide port. Sublimation was collected from 60 seconds to 120 seconds (60 seconds) after the wafer was placed on the hot plate. The flow attachment (detection part) connecting the QCM sensor and the collection funnel of the sublimation amount measurement device was used without a nozzle. Therefore, the airflow flowed unthrottled through the flow path (diameter: 32 mm) between the sensor (quartz crystal oscillator) and the chamber unit, which was 30 mm away from the sensor. The QCM sensor used had an electrode made primarily of silicon and aluminum (AlSi (with Ti vapor-deposited on the surface)), a quartz crystal oscillator diameter (sensor diameter) of 14 mm, an electrode diameter on the quartz crystal oscillator surface of 5 mm, and a resonant frequency of 9 MHz. For each measurement, the QCM sensor was connected to a computer via a serial cable and dedicated software was installed to enable real-time measurement of the sublimation amount. The thickness of the coating film on the wafer used to measure the amount of sublimation was 100 nm.

[0105] The obtained frequency change was converted into grams from the characteristic value of the quartz crystal oscillator used in the measurement, and the relationship between the amount of sublimation per wafer coated with the protective film-forming composition and the passage of time was clarified. Note that the first 60 seconds was a time period in which the device was left to stabilize (no wafer was set), and the measurement values ​​from 60 seconds after the wafer was placed on the hot plate to 120 seconds were the measurement values ​​for the amount of sublimation per wafer. The amount of sublimation per wafer quantified using the sublimation amount measuring device is shown in Table 3 as a sublimation amount ratio. Note that the value for Comparative Example 3 was converted to 1.0, and the amount of sublimation is shown as a relative value.

[0106]

[0107] As shown in Table 1, the protective films formed using the protective film-forming compositions of Examples 1 to 4 to which the present invention was applied had excellent chemical resistance. In contrast, the protective film formed using the protective film-forming composition of Comparative Example 1, which did not contain any additives, had poor chemical resistance. As shown in Table 2, it was confirmed that the protective films formed using the protective film-forming compositions of Examples 1 to 4 to which the present invention was applied had satisfactory performance as anti-reflective films. As shown in Table 3, it was confirmed that the protective films formed using the protective film-forming compositions of Examples 1 to 4 to which the present invention was applied had a 20 to 60% reduction in the amount of sublimation compared to the protective film formed using the protective film-forming composition of Comparative Example 3, which did not contain the additive component (B).

[0108] The composition for forming a protective film according to the present invention provides a protective film that has excellent resistance when a wet etching solution is applied in substrate processing and produces a small amount of sublimated material when fired.

[0109] 1 Silicon substrate 2 Protective film

Claims

1. A composition for forming a protective film against a wet etching solution for semiconductors, comprising: component (A): a film-forming component; component (B): a compound selected from the group consisting of condensed tannins (b1) formed by polymerization of a compound having a flavanol skeleton, hydrolyzable tannins (b2) formed by ester bonding between an aromatic compound of gallic acid or ellagic acid and a sugar, and flavonoids (b3) derived from a compound having a flavanone skeleton structure; and component (C): a solvent.

2. The composition for forming a protective film according to claim 1, wherein the component (B) is one or more compounds selected from the group consisting of condensed tannins and hydrolyzable tannins.

3. The composition for forming a protective film according to claim 1, wherein the component (B) is the hydrolyzable tannin.

4. The composition for forming a protective film according to claim 3, wherein the hydrolyzable tannin is tannic acid represented by the following formula (I): (In the above formula (I), each G independently represents a hydrogen atom or a monovalent group represented by the following formula (II).) (In the above formula (II), n represents an integer of 0 to 3. However, the number of benzene rings in the above formula (I) is 4 to 17. * represents a bond.) 5. The composition for forming a protective film according to claim 1, further comprising component (D): a curing catalyst.

6. The composition for forming a protective film according to claim 1, wherein the content of said component (B) is 0.1 to 50 mass % based on the mass of the solid content of said component (A).

7. A protective film against a wet etching solution for semiconductors, which is a fired product of a coating film made of the composition for forming a protective film according to any one of claims 1 to 6.

8. A method for producing a substrate with a protective film used in the production of semiconductors, comprising the step of applying the composition for forming a protective film according to any one of claims 1 to 6 onto a semiconductor substrate and baking the composition to form a protective film.

9. A method for manufacturing a substrate with a resist pattern for use in the manufacture of semiconductors, comprising the steps of: applying a composition for forming a protective film according to any one of claims 1 to 6 onto a semiconductor substrate, baking the composition, and forming a protective film as a resist underlayer film; and forming a resist film on the protective film, either directly or via another layer, and then exposing and developing the resist film to form a resist pattern.

10. A method for manufacturing a semiconductor device, comprising the steps of forming a protective film on a semiconductor substrate, which may have an inorganic film formed on its surface, using a protective film-forming composition according to any one of claims 1 to 6, forming a resist pattern on the protective film, dry etching the protective film using the resist pattern as a mask to expose the surface of the inorganic film or the semiconductor substrate, and wet etching and cleaning the inorganic film or the semiconductor substrate using a semiconductor wet etching solution using the protective film after dry etching as a mask.

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