Etching solution

Abstract

In one embodiment, an etching solution is provided that exhibits excellent storage stability and can suppress etching and improve the quality of the surface of the layer to be etched after etching. In one embodiment, the present disclosure relates to an etching solution for etching a layer to be etched comprising at least one metal, wherein the etching solution is formed by combining a nitrogen-containing compound having a ratio of carbon atoms (C) to nitrogen atoms (N) in one molecule, C / N, of 2.2 or more, an acid including an organic acid, nitric acid, and phosphoric acid, and water, and the amount of organic acid in the etching solution is 50 mass% or more.

Description

Technology Field

[0001] The present disclosure relates to an etching solution and an etching method using the same. Background Technology

[0002] In the manufacturing process of a semiconductor device, for example, a process is performed to etch a layer to be etched, comprising at least one metal such as tungsten, tantalum, zirconium, hafnium, molybdenum, niobium, ruthenium, osmium, rhenium, rhodium, copper, nickel, cobalt, titanium, titanium nitride, alumina, aluminum, and iridium, and process it into a predetermined pattern shape.

[0003] In the recent semiconductor field, high integration is progressing, and there is a demand for increased complexity and miniaturization of wiring. As the demand for pattern processing technology and etching solutions increases, various etching methods and etching solutions are being proposed.

[0004] For example, Japanese Patent Publication No. 2013-237873 (Patent Document 1) proposes an etching solution containing phosphoric acid, nitric acid, and a polyalkylene polyamine containing three or more amino groups in one molecule, which is used for etching a metal film having at least one layer of a metal thin film of molybdenum or a molybdenum alloy.

[0005] Japanese Patent Publication No. 2021-114569 (Patent Document 2) proposes a substrate processing method comprising: a process of supplying a first etching solution, which includes an oxidizing agent (e.g., nitric acid), a catalyst (e.g., phosphoric acid), and a moisture adjusting agent (e.g., an organic acid), wherein the ratio of the moisture adjusting agent is greater than the total ratio of the oxidizing agent and the catalyst, to a substrate having a stacked film including a molybdenum film; and a process of supplying a second etching solution, wherein the ratio of the moisture adjusting agent is greater than that of the first etching solution, to the substrate after supplying the first etching solution to the substrate.

[0006] In Japanese Patent Publication No. 2022-502835 (Patent Document 3), an etching solution for selectively etching aluminum oxide, tungsten and / or titanium nitride is proposed, comprising about 65 to 90 weight% phosphoric acid, about 0.01 to 4 weight% acetic acid, 0.01 to 5 weight% nitric acid, and water.

[0007] The present disclosure relates to an etching solution for etching a layer to be etched comprising at least one metal, wherein, in one embodiment, the etching solution is formed by combining a nitrogen-containing compound having a ratio of carbon atoms (C) to nitrogen atoms (N) in one molecule, C / N, of 2.2 or more, with an acid including an organic acid, nitric acid, and phosphoric acid, and the amount of the organic acid in the etching solution is 50 mass% or more.

[0008] The present disclosure relates to an etching method, wherein, in one embodiment, the method comprises a process of etching a layer to be etched comprising at least one metal using an etching solution of the present disclosure, wherein the temperature of the etching solution during etching is 20°C or higher and 50°C or lower.

[0009] The present disclosure relates to an etching solution for etching a layer to be etched comprising at least one metal in one embodiment, wherein the etching solution comprises a salt of a nitrogen-containing compound having a ratio of carbon atoms (C) to nitrogen atoms (N) in one molecule, C / N, of 2.2 or more, and an acid including an organic acid, nitric acid, and phosphoric acid, and wherein the amount of the organic acid in the etching solution is 50 mass% or more.

[0010] The present disclosure relates to an etching solution for etching a layer to be etched comprising at least one metal, wherein, in one embodiment, the etching solution is formed by combining a nitrogen-containing compound having a ratio of carbon atoms (C) to nitrogen atoms (N) in one molecule, C / N, of 2.2 or more, and an acid including an organic acid, nitric acid, and phosphoric acid, wherein the amount of the organic acid in the etching solution is 80 mass% or more.

[0011] The present disclosure relates to an etching solution for etching a layer to be etched containing molybdenum in one embodiment, wherein the etching solution is formed by combining at least one nitrogen-containing compound having a ratio of carbon atoms (C) to nitrogen atoms (N) in one molecule, C / N, of 2.2 or more, with an acid including an organic acid, nitric acid, and phosphoric acid, and the amount of the organic acid in the etching solution is 50 mass% or more.

[0012] The present disclosure relates to a method for manufacturing an electronic component, comprising, in one embodiment, a process of etching a layer to be etched comprising at least one metal using the etching solution of the present disclosure. Specific details for implementing the invention

[0013] As an etching solution, a mixed acid aqueous solution (strongly acidic aqueous solution) containing phosphoric acid, nitric acid, and an organic acid (e.g., acetic acid) is generally used. In addition, nitrogen-containing compounds are sometimes used as etching inhibitors in the etching solution for reasons such as not damaging the quality of the surface of the layer to be etched (metal film surface) after etching. Patent Document 1 proposes adding polyalkylene polyamine to an etching solution that does not contain acetic acid as an essential component, but there is a problem that if an auxiliary agent such as polyalkylene polyamine is added to the above mixed acid aqueous solution, turbidity occurs and the storage stability of the etching solution deteriorates.

[0014] Accordingly, the present disclosure provides, in one embodiment, an etching solution capable of exhibiting excellent storage stability, suppressing etching, and improving the quality of the surface of the layer to be etched after etching, and an etching method using the same.

[0015] As a result of careful examination by the inventors, it was discovered that by using an etching solution containing or combining a specific nitrogen-containing compound and an acid containing 50 mass% or more of an organic acid, it is possible to suppress etching and improve the quality of the surface of the etched layer after etching (uniform etching of the etched layer), while also improving storage stability.

[0016] The present disclosure relates to an etching solution for etching a layer to be etched comprising at least one metal in one embodiment, wherein the etching solution is formed by combining a nitrogen-containing compound having a ratio of carbon atoms (C) to nitrogen atoms (N) in one molecule of 2.2 or more with an acid including an organic acid, nitric acid, and phosphoric acid, and the amount of the organic acid in the etching solution is 50 mass% or more (hereinafter also referred to as the “etching solution of the present disclosure”).

[0017] According to the present disclosure, in one embodiment, an etching solution can be provided that exhibits excellent storage stability, suppresses etching, and improves the quality of the surface of the etched layer after etching.

[0018] The details of the mechanism of effect manifestation of the present disclosure are not clear, but are presumed as follows.

[0019] When a nitrogen-containing compound, such as a polyvalent amine, is mixed as an etching inhibitor into a mixed acid aqueous solution (strongly acidic aqueous solution) containing phosphoric acid, nitric acid, and an organic acid (e.g., acetic acid), which is commonly used as an etching solution, the polyvalent amine can form a salt with the acid within the mixed acid aqueous solution. In particular, for example, in the case of a polyvalent amine in which the molecule contains a large number of hydrophilic nitrogen atoms, the hydrophilic polyvalent amine and the acid salt are easily soluble in aqueous solvents. In the case of a polyvalent amine in which the molecule contains a large number of hydrophobic methylene groups, the hydrophobic polyvalent amine and the acid salt are difficult to dissolve in aqueous solvents.

[0020] Meanwhile, in a mixed acid aqueous solution (strongly acidic aqueous solution) with a low pH, organic acids are not dissociated, and as the amount of organic acid increases, the hydrophobicity of the mixed acid aqueous solution increases. Consequently, hydrophobic polyamines and acid salts can be dissolved, but hydrophilic polyamines and acid salts are extremely degraded and become cloudy.

[0021] In the present disclosure, it is believed that as an etching inhibitor, a specific nitrogen-containing compound with high hydrophobicity or amphiphilicity (a nitrogen-containing compound having a ratio of carbon atoms (C) to nitrogen atoms (N) in one molecule, C / N, of 2.2 or more) is used, and by combining this nitrogen-containing compound with a mixed acid containing 50 mass% or more of an organic acid, the solubility of the nitrogen-containing compound and the salt of the acid can be improved, and the storage stability of the etching solution can be improved.

[0022] In addition, it is known that a nitrogen-containing compound used as an etching inhibitor acts on a metal surface to inhibit etching by acid. In the present disclosure, since a high concentration of organic acid lowers the viscosity of the mixed acid aqueous solution, the diffusivity of the acid itself or the nitrogen-containing compound is improved, and uniform etching of the surface is achieved. That is, it is believed that etching inhibition and improvement of the surface quality of the etched layer after etching can be achieved.

[0023] However, the present disclosure is not to be interpreted as being limited to these mechanisms.

[0024] [Nitrogen-containing compound (Component A) having a carbon (C) to nitrogen (N) ratio of 2.2 or higher in one molecule (C / N)]

[0025] The etching solution of the present disclosure is formed by containing or combining a nitrogen-containing compound (hereinafter also referred to as “Component A”) having a ratio of carbon atoms (C) to nitrogen atoms (N) in one molecule, C / N, of 2.2 or more.

[0026] The number of carbon atoms (C) in one molecule of component A is preferably 4 or more and more preferably 8 or more from the perspective of storage stability and etching inhibition, and is preferably 24 or less and more preferably 18 or less from the perspective of improving the quality of the etched layer. From the same perspective, the number of carbon atoms in one molecule of component A is preferably 4 or more and 24 or less, and more preferably 8 or more and 18 or less.

[0027] The number of nitrogen atoms (N) in one molecule of component A is preferably 1 or more, more preferably 2 or more, from the perspective of storage stability and etching inhibition, and is preferably 3 or less from the perspective of improving the quality of the etched layer. From the same perspective, the number of nitrogen atoms in one molecule of component A is preferably 1 or more and 3 or less.

[0028] In one or more embodiments, the ratio C / N of the number of carbon atoms (C) and nitrogen atoms (N) in one molecule of component A is 2.2 or higher, preferably 2.3 or higher, more preferably 4 or higher, and even more preferably 8 or higher, from the perspective of storage stability and etching inhibition, and is preferably 20 or lower, and more preferably 18 or lower, from the perspective of improving the quality of the etched layer. More specifically, the ratio C / N of component A is preferably 2.2 or higher and 20 or lower, more preferably 4 or higher and 18 or lower, and even more preferably 8 or higher and 18 or lower.

[0029] Component A included in or formulated in the etching solution of the present disclosure is, in one or more embodiments, at least one nitrogen-containing compound selected from aliphatic amines, aromatic amines, and amino alcohols.

[0030] Ingredient A may be one type or a combination of two or more types.

[0031] In one or more embodiments, component A may be in the form of a salt of the nitrogen-containing compound. In one or more embodiments, component A may form an acid and a salt in the etching solution.

[0032] Accordingly, the present disclosure relates to an etching solution for etching a layer to be etched comprising at least one metal in another embodiment, the etching solution comprising a salt of component A and an acid including an organic acid, nitric acid and phosphoric acid, wherein the amount of the organic acid in the etching solution is 50 mass% or more.

[0033] (Aliphatic amines)

[0034] As component A, an aliphatic amine is exemplified in one or more embodiments. As an aliphatic amine, a primary, secondary, or tertiary aliphatic amine is exemplified. The aliphatic amine may be a single type or a combination of two or more types.

[0035] In the present disclosure, a primary, secondary, or tertiary aliphatic amine is a compound in which at least one hydrogen atom of ammonia (NH3) is substituted with a hydrocarbon group. In one or more embodiments, a primary aliphatic amine is one in which one hydrogen atom of ammonia is substituted with a hydrocarbon group, a secondary aliphatic amine is one in which two hydrogen atoms of ammonia are substituted with a hydrocarbon group, and a tertiary aliphatic amine is one in which three hydrogen atoms of ammonia are substituted with a hydrocarbon group. Examples of the hydrocarbon group include, for instance, a hydrocarbon group having 1 to 24 carbon atoms. The hydrocarbon group may be straight-chain, branched-chain, or cyclic. The hydrocarbon group may contain unsaturated bonds. The hydrocarbon group may have a portion substituted with oxygen atoms, etc.

[0036] The number of carbon atoms of the above aliphatic amine is preferably 4 or more and more preferably 8 or more from the perspective of storage stability and etching inhibition, and is preferably 24 or less and more preferably 18 or less from the perspective of improving the quality of the etched layer. From the same perspective, the number of carbon atoms of the primary, secondary, or tertiary aliphatic amine is preferably 4 or more and 24 or less, and more preferably 8 or more and 18 or less.

[0037] The ratio of the number of carbon atoms (C) to the number of nitrogen atoms (N) in one molecule of the aliphatic amine, C / N, is preferably 4 or more and more preferably 6 or more from the perspective of storage stability, and is preferably 24 or less, more preferably 20 or less, and even more preferably 18 or less from the perspective of improving the quality of the etched layer. From the same perspective, the ratio of the number of carbon atoms to the number of nitrogen atoms, C / N, in one molecule of the aliphatic amine is preferably 4 or more and 24 or less, more preferably 6 or more and 20 or less, and even more preferably 6 or more and 18 or less.

[0038] Examples of the above primary aliphatic amines include oleylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, 2-ethylhexylamine, nonylamine, aminodecane, aminoundecane, aminododecane (dodecylamine), aminotridecane, tetradecylamine, aminopentadecane, hexadecylamine, aminoheptadecane, stearylamine (octadecylamine), aminononadecane, 2-ethylhexylamine, etc.

[0039] Examples of the above secondary aliphatic amines include methylhexylamine, methylpentylamine, methyloctylamine, methylnonylamine, methyldecylamine, methylundecylamine, methyldodecylamine, methyloctadecylamine, cyclohexylamine, bis(hexamethylene)triamine, N-butylethylenediamine, etc.

[0040] Examples of the above tertiary aliphatic amines include dimethylbutylamine, dimethylpentylamine, dimethylhexylamine, methylpentylamine, methyloctylamine, methylnonylamine, methyldecylamine, methylundecylamine, methyldodecylamine, dimethyloctadecylamine, etc.

[0041] The above aliphatic amine may be one or more compounds represented by the following formula (I) in one or more embodiments.

[0042] [Chemical Formula 1]

[0043]

[0044] Among the above equation (I), R 1The group is a straight-chain or branched-chain alkyl group having 1 to 18 carbon atoms, a straight-chain or branched-chain alkenyl group having 1 to 18 carbon atoms, or a cyclic hydrocarbon group having 1 to 18 carbon atoms, and the alkyl group, the alkenyl group, and the cyclic hydrocarbon group may include an amino group or an ether bond.

[0045] R 2 and R 3 Each is independently a hydrogen atom, a straight-chain or branched-chain alkyl group having 1 to 8 carbon atoms, a straight-chain or branched-chain alkenyl group having 1 to 8 carbon atoms, or a cyclic hydrocarbon group having 1 to 8 carbon atoms, and the alkyl group, the alkenyl group and the cyclic hydrocarbon group may include an amino group or an ether bond.

[0046] In the above formula (I), with respect to etching inhibition and improvement of the quality of the layer to be etched, R1 is preferably exemplified as a straight-chain alkyl group having 1 to 18 carbon atoms, a straight-chain alkyl group having 1 to 18 carbon atoms having an amino group, or a branched-chain alkenyl group having 1 to 18 carbon atoms. 2 and R 3 Each is preferably exemplified independently by a straight-chain alkyl group having 1 to 8 carbon atoms, having a hydrogen atom, a methyl group, or an amino group.

[0047] (Aromatic amine)

[0048] As component A, an aromatic amine is exemplified in one or more embodiments. The aromatic amine may be one type or a combination of two or more types.

[0049] In the present disclosure, an aromatic amine is a compound in which at least one hydrogen atom of ammonia (NH3) is substituted with an aromatic ring. For the sake of inhibiting etching and improving the quality of the layer to be etched, a primary aromatic amine in which one hydrogen atom of ammonia is substituted with an aromatic ring is preferred. As an aromatic ring, for example, a benzene ring is exemplified. The aromatic ring may have a substituent. As a substituent, an alkyl group having 1 to 12 carbon atoms is exemplified. The alkyl group may be either straight-chain or branched-chain. As a branched-chain alkyl group, an isopropyl group is exemplified.

[0050] Examples of the above aromatic amines include, in terms of etching inhibition and storage stability, aniline derivatives (e.g., aniline, 2,6-diisopropylaniline, etc.); triazole derivatives (e.g., benzotriazole, 5-methylbenzotriazole, etc.); imidazole derivatives; quinoline derivatives (e.g., isoquinoline, etc.).

[0051] (Amino alcohol)

[0052] As component A, in one or more embodiments, an amino alcohol is exemplified. The amino alcohol may be one type or a combination of two or more types.

[0053] In the present disclosure, an amino alcohol (alkanolamine) is a compound having a hydroxyl group and an amino group. As for the amino group, a primary, secondary, or tertiary amino group is exemplified, and a primary amino group is preferred from the viewpoint of inhibiting etching and improving the quality of the layer to be etched.

[0054] As for the number of carbon atoms of the above amino alcohol, from the perspective of storage stability, it is preferable to have 2 or more and 24 or fewer, more preferable to have 4 or more and 18 or fewer, and even more preferable to have 4 or more and 12 or fewer.

[0055] Examples of the above amino alcohols include, for instance, 2-(2-aminoethoxy)ethanol, triethanolamine, etc.

[0056] The above amino alcohol (component A) may be one or more compounds represented by the following formula (II) in one or more embodiments.

[0057] [Chemical Formula 2]

[0058]

[0059] Among the above equation (II), R 4 is a straight-chain or branched-chain alkyl group having 2 to 6 carbon atoms, and the alkyl group may have an ether group.

[0060] R 5 and R 6 Each is independently a hydrogen atom or a straight-chain or branched-chain alkyl group having 2 to 6 carbon atoms, and the alkyl group may have an amino group, a hydroxyl group, or an ether group.

[0061] Among the above equation (II), in terms of etching inhibition and improvement of the quality of the layer to be etched, R 4 It is preferable that the alkyl group of is straight-chain. In the same regard, R 4 Preferably, a straight-chain alkyl group having 2 to 6 carbon atoms having an ether group, and R 5 and R 6 Each of them is independently preferred to have hydrogen atoms.

[0062] As for component A, in one or more embodiments, at least one selected from butylamine, octylamine, dodecylamine, octadecylamine, methyl octadecylamine, dimethyl octadecylamine, oleylamine, 2-ethylhexylamine, bis(hexamethylene)triamine, aniline, 2,6-diisopropylaniline, 5-methylbenzotriazole, and 2-(2-aminoethoxy)ethanol is preferred from the viewpoint of inhibiting etching and improving the quality of the layer to be etched, and at least one selected from dodecylamine, octadecylamine, methyl octadecylamine, dimethyl octadecylamine, oleylamine, bis(hexamethylene)triamine, aniline, 2,6-diisopropylaniline, 5-methylbenzotriazole, and 2-(2-aminoethoxy)ethanol is more preferred.

[0063] The molecular weight of component A included in the etching solution of the present disclosure is preferably 70 or more, more preferably 120 or more, and more preferably 150 or more, from the perspective of inhibiting etching and improving the quality of the layer to be etched, and is preferably 350 or less, more preferably 300 or less, and more preferably 250 or less. More specifically, the molecular weight of component A is preferably 70 or more and 350 or less, more preferably 120 or more and 300 or less, and more preferably 150 or more and 250 or less.

[0064] The amount of component A in the etching solution of the present disclosure is preferably 0.01 mass% or more, more preferably 0.1 mass% or more, and more preferably 0.5 mass% or more, from the perspective of inhibiting etching and improving the quality of the layer to be etched; and from the perspective of storage stability, it is preferably 5 mass% or less, more preferably 3 mass% or less, and more preferably 2 mass% or less. In the same view, the amount of component A in the etching solution of the present disclosure is preferably 0.01 mass% or more and 5 mass% or less, more preferably 0.1 mass% or more and 3 mass% or less, and more preferably 0.5 mass% or more and 2 mass% or less. When component A is a combination of two or more types, the amount of component A is the total amount of these.

[0065] [mountain]

[0066] The acid included in or blended in the etching solution of the present disclosure is an acid including an organic acid, nitric acid, and phosphoric acid. For the sake of storage stability, the acid included in or blended in the etching solution of the present disclosure is exemplified in one or more embodiments as being composed of an organic acid, nitric acid, and phosphoric acid (mixed acid).

[0067] The amount of acid in the etching solution of the present disclosure is preferably 70 mass% or more, more preferably 80 mass% or more, and even more preferably 90 mass% or more from the perspective of etching inhibition and storage stability.

[0068] (Organic acid)

[0069] As for the organic acid, at least one selected from acetic acid, acetic anhydride, methoxyacetic acid, ethoxyacetic acid, propionic acid, butanoic acid, citric acid, formic acid, gluconic acid, glycolic acid, malonic acid, oxalic acid, lactic acid, and pentacarbonate is exemplified from the perspective of storage stability. Among these, as for the same perspective, at least one selected from acetic acid, acetic anhydride, methoxyacetic acid, and ethoxyacetic acid is preferred as the organic acid, and acetic acid is more preferred. The organic acid may be a single type or a combination of two or more types. When acetic anhydride is used as the organic acid when preparing the etching solution of the present disclosure, the acetic anhydride reacts with water in the etching solution to be converted into acetic acid and water, thereby enabling a reduction in the amount of water in the etching solution.

[0070] The amount of organic acid incorporated in the etching solution of the present disclosure is 50 mass% or more, preferably 70 mass% or more, more preferably 80 mass% or more or 85 mass% or more, and preferably 95 mass% or less, and more preferably 90 mass% or less, from the perspective of improving the quality and preservation stability of the etched layer and reducing the viscosity of the etching solution. More specifically, the amount of organic acid incorporated in the etching solution of the present disclosure is preferably 50 mass% or more and 95 mass% or less, and more preferably 70 mass% or more and 90 mass% or less, or 80 mass% or more and 90 mass% or less. In the case where the organic acid is a combination of two or more types, the amount of organic acid incorporated is the total amount of these.

[0071] Accordingly, the present disclosure relates to an etching solution for etching a layer to be etched comprising at least one metal in another embodiment, wherein the etching solution is formed by combining component A with an acid comprising an organic acid, nitric acid, and phosphoric acid, and the amount of the organic acid in the etching solution is 80 mass% or more.

[0072] (nitric acid)

[0073] The amount of nitric acid incorporated in the etching solution of the present disclosure is preferably 0.1 mass% or more, more preferably 0.5 mass% or more, and more preferably 1 mass% or more, from the perspective of improving the quality of the layer to be etched, and is preferably 10 mass% or less, more preferably 8 mass% or less, and more preferably 5 mass% or less, from the perspective of improving the quality of the layer to be etched and preservation stability. More specifically, the amount of nitric acid incorporated in the etching solution of the present disclosure is preferably 0.1 mass% or more and 10 mass% or less, more preferably 0.5 mass% or more and 8 mass% or less, and more preferably 1 mass% or more and 5 mass% or less.

[0074] (Phosphoric acid)

[0075] The amount of phosphoric acid in the etching solution of the present disclosure is preferably 0.1 mass% or more, more preferably 0.5 mass% or more, and more preferably 1 mass% or more, from the perspective of improving the quality of the layer to be etched, and is preferably 40 mass% or less, more preferably 20 mass% or less, and more preferably 10 mass% or less, from the perspective of improving the quality of the layer to be etched and preservation stability. More specifically, the amount of phosphoric acid in the etching solution of the present disclosure is preferably 0.1 mass% or more and 40 mass% or less, more preferably 0.5 mass% or more and 20 mass% or less, and more preferably 1 mass% or more and 10 mass% or less.

[0076] In the etching solution of the present disclosure, the mass ratio (organic acid / phosphoric acid) of the blended amounts of organic acid and phosphoric acid is preferably 1.2 or more, more preferably 3.5 or more, 5 or more, or 6 or more, and likewise, in terms of etching inhibition, is preferably 950 or less, and more preferably 100 or less, 50 or less, or 20 or less. More specifically, in the etching solution of the present disclosure, the mass ratio (organic acid / phosphoric acid) is preferably 1.2 or more and 950 or less, and more preferably 3.5 or more and 100 or less, 5 or more and 50 or less, or 6 or more and 20 or less.

[0077] In the etching solution of the present disclosure, the mass ratio (organic acid / nitrogen-containing compound) of the blended amount of the organic acid and the nitrogen-containing compound (component A) is preferably 10 or more, more preferably 20 or more, more preferably 30 or more, more preferably 40 or more, more preferably 50 or more, and in the same view, is preferably 10,000 or less, more preferably 5,000 or less, more preferably 2,500 or less, more preferably 1,000 or less, more preferably 500 or less, and more preferably 100 or less. More specifically, in the etching solution of the present disclosure, the mass ratio (organic acid / nitrogen-containing compound) is preferably 10 or more and 10,000 or less, more preferably 20 or more and 5,000 or less, even more preferably 30 or more and 2,500 or less, even more preferably 40 or more and 1,000 or less, even more preferably 50 or more and 500 or less, and even more preferably 50 or more and 100 or less.

[0078] (Other mountain)

[0079] The acid included in or blended in the etching solution of the present disclosure may additionally contain other acids other than nitric acid, phosphoric acid, and organic acids. Examples of other acids include inorganic acids other than nitric acid and phosphoric acid. Examples of inorganic acids include hydrochloric acid, sulfuric acid, hydrofluoric acid, etc.

[0080] [water]

[0081] The etching solution of the present disclosure is further composed of water or water in one or more embodiments. Examples of water included in or combined with the etching solution of the present disclosure include distilled water, ion-exchanged water, pure water, and ultrapure water.

[0082] The amount of water in the etching solution of the present disclosure is preferably 10 mass% or less, more preferably 8 mass% or less, and even more preferably 5 mass% or less, from the perspective of improving the quality of the layer to be etched.

[0083] [Other ingredients]

[0084] The etching solution of the present disclosure may be formed by additionally incorporating other components to the extent that the effects of the present disclosure are not impaired. Examples of other components include chelating agents, surfactants, solubilizing agents, preservatives, rust inhibitors, disinfectants, antibacterial agents, antioxidants, etc.

[0085] The etching solution of the present disclosure may, in one or more embodiments, substantially not contain polyalkyleneimine and polyalkylene polyamine. As the polyalkyleneimine, polyethyleneimine is exemplified, for example. As the polyalkylene polyamine, polyalkylene polyamine containing three or more amino groups in one molecule is exemplified, and triethylenetetramine is exemplified, for example.

[0086] The content of polyalkyleneimine and polyalkylenepolyamine in the etching solution of the present disclosure is preferably less than 0.01 mass%, more preferably 0.001 mass% or less, and even more preferably 0 mass% (i.e., not included).

[0087] [Method for preparing etching solution]

[0088] The etching solution of the present disclosure is obtained, in one embodiment, by combining component A, an acid including an organic acid, nitric acid, and phosphoric acid, water, and, if desired, any of the components described above by a known method. Accordingly, the present disclosure relates to a method for preparing an etching solution (hereinafter also referred to as the "method for preparing an etching solution of the present disclosure") comprising, in one embodiment, a process of combining at least component A, an organic acid, nitric acid, phosphoric acid, and water.

[0089] In the present disclosure, the phrase “mixing at least component A, an organic acid, a nitric acid, a phosphoric acid, and water” includes, in one or more embodiments, mixing component A, an organic acid, a nitric acid, a phosphoric acid, water, and, if necessary, any of the above-described components simultaneously or in sequence. The order of mixing is not particularly limited. The mixing may be performed using a mixer such as, for example, a propeller-type stirrer, a pump-driven liquid circulation stirrer, a homomixer, a homogenizer, an ultrasonic disperser, and a wet ball mill.

[0090] In the method for preparing an etching solution of the present disclosure, the preferred amount of each component can be the same as the preferred amount of each component in the etching solution of the present disclosure described above.

[0091] In the present disclosure, "amount of each component in the etching solution" refers to the amount of each component in the etching solution at the time of initiation of use for the etching process, that is, at the time of use for the etching treatment, in one or more embodiments.

[0092] The blending amount of each component in the etching solution of the present disclosure may be considered as the content of each component in the etching solution of the present disclosure in one or more embodiments. However, in cases where neutralization is applied, the blending amount and the content may differ.

[0093] Embodiments of the etching solution of the present disclosure may be of the so-called one-component type, supplied to the market in a state where all components are pre-mixed, or of the so-called two-component type, mixed upon use. As an example of an embodiment of the two-component etching solution, it is exemplified that the solution comprises a solution containing component A (first solution) and an aqueous acid solution containing an organic acid, nitric acid, and phosphoric acid (second solution), wherein the first solution and the second solution are mixed upon use. After the first solution and the second solution are mixed, they may be diluted using water or an aqueous acid solution as needed. The first solution or the second solution may contain all or part of the water used in the preparation of the etching solution. The first solution and the second solution may each contain any of the components described above as needed.

[0094] The pH of the etching solution of the present disclosure is preferably 2 or lower, and more preferably 1 or lower, from the perspective of storage stability. In addition, the pH of the etching solution of the present disclosure can be preferably -2.5 or higher, and more preferably -2 or higher. In the present disclosure, the pH of the etching solution is a value at 25°C and can be measured using a pH meter, and specifically, can be measured by the method described in the examples.

[0095] The viscosity of the etching solution of the present disclosure at 25°C is preferably 1 mPa·s or more, more preferably 2 mPa·s or more, from the perspective of improving the quality of the layer to be etched, and is preferably 40 mPa·s or less, more preferably 25 mPa·s or less, and even more preferably 10 mPa·s or less. More specifically, the viscosity of the etching solution of the present disclosure is preferably 1 mPa·s or more and 25 mPa·s or less, and more preferably 2 mPa·s or more and 10 mPa·s or less. In the present disclosure, the viscosity of the etching solution can be measured using a general-purpose viscometer such as a Type B viscometer or a Ubélode viscometer, and specifically, can be measured by the method described in the examples. The viscosity of the etching solution at 25°C can be adjusted, for example, by water or an organic solvent.

[0096] The etching solution of the present disclosure may be preserved and supplied in a concentrated state to the extent that its stability is not compromised. In this case, it is preferable in that it can reduce manufacturing and transportation costs. Furthermore, this concentrated solution may be appropriately diluted using water or an aqueous acid solution as needed and used in an etching process. The dilution ratio may be, for example, 5 to 100 times.

[0097] [Kit]

[0098] The present disclosure relates to a kit for preparing the etching solution of the present disclosure in another embodiment (hereinafter also referred to as the “kit of the present disclosure”).

[0099] As a kit of the present disclosure, for example, a kit (two-component etching solution) is exemplified by comprising a solution containing component A (first solution) and an aqueous acid solution containing an organic acid, nitric acid, and phosphoric acid (second solution) in an unmixed state, wherein they are mixed upon use. After the first solution and the second solution are mixed, they may be diluted using water or an aqueous acid solution as needed. The first solution or the second solution may contain all or part of the water used to prepare the etching solution. The first solution and the second solution may each contain any of the components described above as needed. According to the kit of the present disclosure, an etching solution with excellent storage stability can be prepared.

[0100] [Etched layer]

[0101] The etching layer to be etched using the etching solution of the present disclosure is, in one or more embodiments, a etching layer comprising at least one metal. Here, the metal is not particularly limited as long as it exhibits the effects of the present disclosure, but for example, at least one metal selected from tungsten, tantalum, zirconium, hafnium, molybdenum, niobium, ruthenium, osmium, rhenium, rhodium, copper, nickel, cobalt, titanium, titanium nitride, alumina, aluminum, and iridium is exemplified. Among these, the etching solution of the present disclosure is preferably used for etching a etching layer comprising at least one metal selected from tungsten, molybdenum, niobium, tantalum, and zirconium in one or more embodiments, and is suitably used for etching a molybdenum film in one or more embodiments. That is, as the etching layer, a molybdenum film is exemplified in one or more embodiments.

[0102] Accordingly, the present disclosure relates to an etching solution for etching a layer to be etched containing molybdenum in another embodiment, wherein the etching solution is formed by combining component A with an acid including an organic acid, nitric acid, and phosphoric acid, and the amount of the organic acid in the etching solution is 50 mass% or more.

[0103] The above-mentioned etched layer is an etched layer formed on a substrate in one or more embodiments. As a substrate, at least one substrate selected from a semiconductor wafer (semiconductor substrate), a substrate for a liquid crystal display device, a substrate for a plasma display, a substrate for a Field Emission Display (FED), a substrate for an optical disc, a substrate for a magnetic disc, a substrate for a magneto-optical disc, a substrate for a photomask, a ceramic substrate, and a substrate for a solar cell is exemplified.

[0104] [Etching Method]

[0105] The present disclosure relates to an etching method (hereinafter referred to as the "etching method of the present disclosure") comprising, in one embodiment, a process for etching a layer to be etched comprising at least one metal using an etching solution of the present disclosure (hereinafter also referred to as the "etching process of the present disclosure"), wherein the temperature of the etching solution during etching is 20°C or higher and 50°C or lower. According to the etching method of the present disclosure, in one or more embodiments, the productivity of a semiconductor substrate can be improved by using an etching solution with excellent storage stability.

[0106] In the etching process of the present disclosure, etching treatment methods include, for example, immersion etching, single-wafer etching, etc.

[0107] In the etching process of the present disclosure, the temperature of the etching solution (etching temperature) during etching is preferably 20°C or higher, more preferably 25°C or higher, and more preferably 30°C or higher, and in terms of improving the quality of the layer to be etched, it is preferably 50°C or lower, more preferably 45°C or lower, and more preferably 40°C or lower. More specifically, the etching temperature is preferably 20°C or higher and 50°C or lower, more preferably 25°C or higher and 45°C or lower, and more preferably 30°C or higher and 40°C or lower.

[0108] In the etching process of the present disclosure, the etching time can be set, for example, from 1 minute to 180 minutes. From the perspective of improving the quality of the layer to be etched, it is preferably from 15 minutes to 90 minutes, more preferably from 30 minutes to 60 minutes.

[0109] The etching solution and the etching method of the present disclosure may be used to etch a metal in a manufacturing process of an electronic device, particularly a semiconductor wafer (semiconductor substrate), in one or more embodiments. As the metal, the metal described above is exemplified.

[0110] The etching solution and the etching method of the present disclosure can be suitably used in one or more embodiments for the fabrication of at least one substrate selected from a semiconductor wafer (semiconductor substrate), a substrate for a liquid crystal display device, a substrate for a plasma display, a substrate for a Field Emission Display (FED), a substrate for an optical disc, a substrate for a magnetic disc, a substrate for a magneto-optical disc, a substrate for a photomask, a ceramic substrate, and a substrate for a solar cell. By doing so, uniform etching of the layer to be etched can be realized, and productivity and yield can be improved.

[0111] The etching solution and the etching method of the present disclosure may be used to etch electrodes in a manufacturing process of an electronic device, particularly a semiconductor memory such as a non-volatile memory including a NAND-type flash memory, in one or more embodiments.

[0112] The etching solution and the etching method of the present disclosure can be suitably used for fabricating patterns having a three-dimensional structure in one or more embodiments. By doing so, high-capacity devices such as memory can be obtained.

[0113] The etching solution and the etching method of the present disclosure may be used in an etching method such as that disclosed in Japanese Patent Publication No. 2020-145412, for example.

[0114] [Method for manufacturing electronic components]

[0115] The present disclosure relates to a method for manufacturing an electronic component (hereinafter also referred to as the "method for manufacturing an electronic component of the present disclosure") comprising, in one embodiment, a process (etching process) for etching a layer to be etched comprising at least one metal using an etching solution of the present disclosure. Examples of electronic components include, for instance, at least one substrate selected from a semiconductor wafer (semiconductor substrate), a substrate for a liquid crystal display device, a substrate for a plasma display, a substrate for a Field Emission Display (FED), a substrate for an optical disc, a substrate for a magnetic disc, a substrate for a magneto-optical disc, a substrate for a photomask, a ceramic substrate, and a substrate for a solar cell; semiconductor memory such as a non-volatile memory including a NAND-type flash memory; etc. As for the etching treatment method or etching treatment condition in the etching process of the method for manufacturing an electronic component of the present disclosure, the same etching treatment method or etching treatment condition as the etching process of the etching method of the present disclosure described above is exemplified. As an etching layer, the etching layer described above is exemplified.

[0116] The present disclosure also relates to one or more of the following embodiments.

[0117] <1> As an etching solution for etching a layer to be etched comprising at least one type of metal,

[0118] A nitrogen-containing compound having a ratio of carbon atoms (C) to nitrogen atoms (N) in one molecule, C / N, of 2.2 or more, and

[0119] Acids including organic acids, nitric acid, and phosphoric acid

[0120] It is formed by combining,

[0121] An etching solution having an organic acid content of 50 mass% or more.

[0122] <2> As an etching solution for etching a layer to be etched comprising at least one type of metal,

[0123] A salt of a nitrogen-containing compound having a ratio of carbon atoms (C) to nitrogen atoms (N) in one molecule, C / N, of 2.2 or more, and

[0124] Acids including organic acids, nitric acid, and phosphoric acid

[0125] Contains,

[0126] An etching solution having an organic acid content of 50 mass% or more.

[0127] <3> As an etching solution for etching a layer to be etched comprising at least one type of metal,

[0128] A nitrogen-containing compound having a ratio of carbon atoms (C) to nitrogen atoms (N) in one molecule, C / N, of 2.2 or more, and

[0129] Acids including organic acids, nitric acid, and phosphoric acid

[0130] It is formed by combining,

[0131] An etching solution having an organic acid content of 80 mass% or more.

[0132] <4> As an etching solution for etching a layer to be etched containing molybdenum,

[0133] At least one nitrogen-containing compound having a ratio of carbon atoms (C) to nitrogen atoms (N) in one molecule, C / N, of 2.2 or more, and

[0134] Acids including organic acids, nitric acid, and phosphoric acid

[0135] It is formed by combining,

[0136] An etching solution having an organic acid content of 50 mass% or more.

[0137] <5> The above nitrogen-containing compound is at least one selected from aliphatic amines, aromatic amines, and amino alcohols, <1> inside <4> Etching solution listed in any one of the following.

[0138] <6> The above-mentioned aliphatic amine is one in which the ratio of the number of carbon atoms (C) to the number of nitrogen atoms (N) in one molecule, C / N, is 4 or more, <5> Etching solution as described in

[0139] <7> The above nitrogen-containing compound is a primary, secondary, or tertiary aliphatic amine, <1> inside <6> Etching solution listed in any one of the following.

[0140] <8> The above primary aliphatic amine is one or more selected from oleylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, 2-ethylhexylamine, nonylamine, aminodecane, aminoundecane, aminododecane (dodecylamine), aminotridecane, tetradecylamine, aminopentadecane, hexadecylamine, aminoheptadecane, stearylamine (octadecylamine), aminononadecane, and 2-ethylhexylamine, <7> Etching solution as described in

[0141] <9> The above secondary aliphatic amine is one or more selected from methylhexylamine, methylpentylamine, methyloctylamine, methylnonylamine, methyldecylamine, methylundecylamine, methyldodecylamine, methyloctadecylamine, cyclohexylamine, bis(hexamethylene)triamine, and N-butylethylenediamine, <7> or <8> Etching solution as described in

[0142] <10> The above tertiary aliphatic amine is one or more selected from dimethylbutylamine, dimethylpentylamine, dimethylhexylamine, methylpentylamine, methyloctylamine, methylnonylamine, methyldecylamine, methylundecylamine, methyldodecylamine, and dimethyloctadecylamine, <7> inside <9> Etching solution listed in any one of the following.

[0143] <11> The above aliphatic amine is one or more of the compounds represented by the following formula (I), <5> inside <10> Etching solution listed in any one of the following.

[0144] [Chemical Formula 3]

[0145]

[0146] Among the above equation (I), R 1The group is a straight-chain or branched-chain alkyl group having 1 to 18 carbon atoms, a straight-chain or branched-chain alkenyl group having 1 to 18 carbon atoms, or a cyclic hydrocarbon group having 1 to 18 carbon atoms, and the alkyl group, the alkenyl group, and the cyclic hydrocarbon group may include an amino group or an ether bond.

[0147] R 2 and R 3 Each independently comprises a hydrogen atom, a straight-chain or branched-chain alkyl group having 1 to 8 carbon atoms, a straight-chain or branched-chain alkenyl group having 1 to 8 carbon atoms, or a cyclic hydrocarbon group having 1 to 8 carbon atoms, and the alkyl group, the alkenyl group and the cyclic hydrocarbon group may include an amino group or an ether bond.

[0148] <12> The above aromatic amine is one or more selected from aniline derivatives (e.g., aniline, 2,6-diisopropylaniline, etc.); triazole derivatives (e.g., benzotriazole, 5-methylbenzotriazole, etc.); imidazole derivatives; and quinoline derivatives (e.g., isoquinoline, etc.). <5> inside <11> Etching solution listed in any one of the following.

[0149] <13> The above amino alcohol is one or more of the compounds represented by the following formula (II), <5> inside <12> Etching solution listed in any one of the following.

[0150] [Chemical Formula 4]

[0151]

[0152] Among the above equation (II), R 4 It is a straight-chain or branched-chain alkyl group having 2 to 6 carbon atoms, and the alkyl group may have an ether group.

[0153] R 5 and R 6Each independently is a hydrogen atom or a straight-chain or branched-chain alkyl group having 2 to 6 carbon atoms, and the alkyl group may have an amino group, a hydroxyl group, or an ether group.

[0154] <14> The above organic acid is at least one selected from acetic acid, acetic anhydride, methoxyacetic acid, ethoxyacetic acid, propionic acid, butyric acid, citric acid, formic acid, gluconic acid, glycolic acid, malonic acid, oxalic acid, lactic acid, and pentacarbonate. <1> inside <13> Etching solution listed in any one of the following.

[0155] <15> The blending amount of the above nitrogen-containing compound is 0.01 mass% or more and 5 mass% or less, or 0.1 mass% or more and 3 mass% or less, or 0.5 mass% or more and 2 mass% or less, <1> inside <14> Etching solution listed in any one of the following.

[0156] <16> The blending amount or content of the above organic acid is 50 mass% or more and 95 mass% or less, or 70 mass% or more and 90 mass% or less, <1> inside <15> Etching solution listed in any one of the following.

[0157] <17> The blending amount or content of the above nitric acid is 0.1 mass% or more and 10 mass% or less, or 0.5 mass% or more and 8 mass% or less, or 1 mass% or more and 5 mass% or less, <1> inside <16> Etching solution listed in any one of the following.

[0158] <18> The blending amount or content of the above phosphoric acid is 0.1 mass% or more and 40 mass% or less, or 0.5 mass% or more and 20 mass% or less, or 1 mass% or more and 10 mass% or less, <1> inside <17> Etching solution listed in any one of the following.

[0159] <19> The mass ratio (organic acid / phosphoric acid) of the blending amount or content of the above organic acid and the above phosphoric acid is 1.2 or more and 950 or less, or 3.5 or more and 100 or less, or 5 or more and 50 or less, or 6 or more and 20 or less, <1> inside <18> Etching solution listed in any one of the following.

[0160] <20> The mass ratio of the blending amount or content of the above organic acid and the above nitrogen-containing compound (organic acid / nitrogen-containing compound) is 10 or more and 10,000 or less, or 20 or more and 5,000 or less, or 30 or more and 2,500 or less, or 40 or more and 1,000 or less, or 50 or more and 500 or less, or 50 or more and 100 or less, <1> inside <19> Etching solution listed in any one of the following.

[0161] <21> Made by adding water, <1> inside <20> Etching solution listed in any one of the following.

[0162] <22> The pH of the above etching solution is 2 or less, or 1 or less, <1> inside <21> Etching solution listed in any one of the following.

[0163] <23> The pH of the above etching solution is -2.5 or higher, or -2 or higher, <1> inside <22> Etching solution listed in any one of the following.

[0164] <24> The viscosity of the above etching solution at 25°C is 1 mPa·s or more and 25 mPa·s or less, or 2 mPa·s or more and 10 mPa·s or less, <1> inside <23> Etching solution listed in any one of the following.

[0165] <25> <1> inside <24> An etching method comprising a process of etching a layer to be etched containing at least one metal using an etching solution described in any one of the above, wherein the temperature of the etching solution during etching is 20°C or higher and 50°C or lower.

[0166] <26> As an etching solution for etching a layer to be etched comprising at least one type of metal,

[0167] A nitrogen-containing compound having a ratio of carbon atoms (C) to nitrogen atoms (N) in one molecule, C / N, of 2.2 or more, and

[0168] Acids including organic acids, nitric acid, and phosphoric acid

[0169] It is formed by combining,

[0170] The nitrogen-containing compound is at least one selected from butylamine, octylamine, dodecylamine, octadecylamine, methyloctadecylamine, dimethyloctadecylamine, oleylamine, 2-ethylhexylamine, bis(hexamethylene)triamine, aniline, 2,6-diisopropylaniline, 5-methylbenzotriazole, and 2-(2-aminoethoxy)ethanol, and

[0171] The amount of organic acid in the etching solution is 50 mass% or more, and

[0172] An etching solution in which the mass ratio (organic acid / nitrogen-containing compound) of the mixture of the organic acid and the nitrogen-containing compound in the etching solution is 10 or more and 10,000 or less.

[0173] <27> <1> inside <24> and <26> A method for manufacturing an electronic component comprising a process of etching a layer to be etched containing at least one metal using an etching solution described in any one of the above.

[0174] Examples

[0175] The present disclosure is described in detail below by way of examples, but the present disclosure is not limited in any way by these examples.

[0176] 1. Preparation of etching solution (Examples 1 to 15, Comparative Examples 1 to 9)

[0177] Etching solutions (pH: -2.0 to -1.5) of Examples 1 to 15 and Comparative Examples 1 to 9 were obtained by combining nitric acid, phosphoric acid, acetic acid, the nitrogen-containing compound shown in Table 1, and water.

[0178] The amount of each component shown in Table 1 is (mass%, effective amount). The amount of water is the remainder excluding acid and nitrogen-containing compounds. In addition, the amount of water includes the amount of water contained in acid aqueous solutions, etc.

[0179] The following components were used to prepare the etching solution.

[0180] Mountain

[0181] Acetic acid [Fujifilm Wako Pure Chemicals Co., Ltd., 100% concentration]

[0182] Nitric acid [Fujifilm Wako Pure Chemicals Co., Ltd., 70% concentration]

[0183] Phosphoric acid [Manufactured by Rinkagaku Kogyo Co., Ltd., concentration 85%]

[0184] Nitrogen-containing compounds

[0185] (Aliphatic amines)

[0186] Butylamine [Tokyo Chemical Industry Co., Ltd.]

[0187] Octylamine [Tokyo Chemical Industry Co., Ltd.]

[0188] Dodecylamine [Tokyo Kasei Kogyo Co., Ltd.]

[0189] Octadecylamine [Tokyo Chemical Industry Co., Ltd.]

[0190] Methyl octadecylamine [Tokyo Kasei Kogyo Co., Ltd.]

[0191] Dimethyl octadecylamine [Tokyo Chemical Industry Co., Ltd.]

[0192] Oleylamine [Tokyo Chemical Industry Co., Ltd.]

[0193] 2-Ethylhexylamine [Tokyo Kasei Kogyo Co., Ltd.]

[0194] Bis(hexamethylene)triamine [Tokyo Chemical Industry Co., Ltd.]

[0195] (Aromatic amine)

[0196] Aniline [Tokyo Chemical Industry Co., Ltd.]

[0197] 2,6-Diisopropylaniline [Tokyo Kasei Kogyo Co., Ltd.]

[0198] 5-Methylbenzotriazole [Tokyo Kasei Kogyo Co., Ltd.]

[0199] (Amino alcohol)

[0200] 2-(2-aminoethoxy)ethanol [Tokyo Kasei Kogyo Co., Ltd.]

[0201] (Phenols)

[0202] Catechol [Tokyo Chemical Industry Co., Ltd.]

[0203] (Polyalkylene polyamine)

[0204] Triethylenetetramine [Molecular weight 146.23, Dosho Corporation]

[0205] (Polyalkyleneimine)

[0206] Polyethyleneimine (PEI) [Number average molecular weight 1,800, "Epomin SP-018" manufactured by Nippon Catalytic Co., Ltd.]

[0207] Water

[0208] Water [Ultrapure water produced using a continuous pure water production device (PureConti PC-2000VRL type) and subsystem (MarkAce KC-05H type) manufactured by Kurita Industrial Co., Ltd.]

[0209] [pH of the etching solution]

[0210] The pH value of the etching solution at 25°C is a value measured using a pH meter (manufactured by Dong-A DKK Co., Ltd.), and is the value after 1 minute of immersing the electrode of the pH meter in the etching solution.

[0211] [Viscosity of the etching solution]

[0212] The viscosity of the etching solution (unit: mPa·s) was measured using the following viscometer under the following conditions.

[0213] Device Name: TVB-10 type viscometer manufactured by Toki Sangyo Co., Ltd. (with constant temperature bath)

[0214] Rotor: Spindle No. M1, Cord No. 20

[0215] Rotation speed: 100 rpm, measure viscosity value after 60 seconds

[0216] Measured temperature: 25℃

[0217] Measure the viscosity 30 minutes after the temperature inside the constant temperature bath indicated by the device reaches 25℃.

[0218] 2. Evaluation of Etching Solution

[0219] [Solubility (Storage Stability)]

[0220] 20 mL of etching solution was prepared by mixing the mixed acid and nitrogen-containing compound shown in Table 1 in the mixing amounts (mass%) shown in Table 1. After stirring for 10 minutes, solubility was checked visually. As criteria for evaluating solubility, A was defined as the case where there is no dissolved residue and the etching solution is colorless transparent or pale yellow transparent in the temperature range of 0°C to 40°C, B was defined as the case where there is a dissolved residue but the etching solution is colorless transparent or pale yellow transparent in the temperature range of 0°C to 40°C, and C was defined as the case where the etching solution is cloudy or in other states (e.g., changes to black) in the temperature range of 0°C to 40°C, as shown in Table 1. Separately, any special notes are also listed in the same column.

[0221] [Evaluation of Etching Inhibition Rate]

[0222] A specific etching solution is taken as an example. If the etching rate of the mixed acid element constituting the etching solution is denoted as α and the etching rate of the etching solution mixed with the mixed acid and a nitrogen-containing compound is denoted as β, the etching inhibition rate is calculated by the following formula. The results are shown in Table 1.

[0223] Etching inhibition rate (%) = 100 × (α―β) / α

[0224] [Condition of the substrate surface]

[0225] A molybdenum plate measuring 2 cm in length, 2 cm in width, and 0.1 mm in thickness, which had been weighed in advance, was immersed in an etching solution prepared with each composition shown in Table 1 (Examples 1 to 15 and Comparative Examples 1 to 5, 9), and the molybdenum plate was etched at each temperature and each treatment time. However, etching solutions containing mixed acid and nitrogen-containing compounds were tested under the same etching conditions. Afterward, after rinsing with water, the surface of the molybdenum plate was observed again using a shape measuring laser microscope VK-9710 (lens magnification 150x) manufactured by KEYENCE, and the resulting image was analyzed using the surface roughness mode of the same device. Then, the surface precision, which serves as an indicator of etching non-uniformity, was calculated using the following formula. The etching non-uniformity of the molybdenum plate was evaluated based on the following evaluation criteria. The results are shown in Table 1.

[0226] Surface precision (%) = Surface roughness after etching / Surface roughness before etching × 100

[0227] <Evaluation Criteria>

[0228] 4: Surface precision less than 150%

[0229] 3: Surface precision 150% or more, less than 200%

[0230] 2: Surface precision 200% or more, less than 300%

[0231] 1: Surface precision 300% or higher

[0232] [Table 1]

[0233]

[0234] As shown in Table 1, it was found that the etching solutions of Examples 1 to 15, which contain nitrogen-containing compounds with a ratio C / N of 2.2 or higher, all have good solubility and excellent storage stability compared to the etching solution of Comparative Example 6, which contains catechol (phenols) instead of nitrogen-containing compounds, and the etching solutions of Comparative Examples 7 to 8, which contain nitrogen-containing compounds with a ratio C / N of less than 2.2.

[0235] In addition, the etching solution of Examples 1 to 15, which contains a nitrogen-containing compound with an acetic acid content of 50 mass% or more and a C / N ratio of 2.2 or more, had excellent etching inhibition and good condition of the substrate surface compared to the etching solution of Comparative Examples 2 to 4, which contains acetic acid content of 50 mass% or more and does not contain a nitrogen-containing compound, and Comparative Example 5, which contains acetic acid content of 30 mass% and does not contain a nitrogen-containing compound.

[0236] In addition, the etching solution of Comparative Example 9, in which the amount of acetic acid was less than 50 mass%, did not have a good condition on the substrate surface compared to Examples 1, 8, and 15, in which the amount of acetic acid was 50 mass% or more.

[0237] Industrial applicability

[0238] The etching solution of the present disclosure is useful in a method for manufacturing a large-capacity semiconductor memory because it has excellent storage stability and can suppress etching and improve the quality of the surface of the layer to be etched after etching.

Claims

Claim 1 An etching solution for etching a layer to be etched containing at least one type of metal, comprising a nitrogen-containing compound having a ratio of carbon atoms (C) to nitrogen atoms (N) in one molecule of 2.2 or more and an acid including an organic acid, nitric acid, and phosphoric acid, wherein the amount of organic acid in the etching solution is 50 mass% or more. Claim 2 An etching solution according to claim 1, wherein the nitrogen-containing compound is at least one selected from aliphatic amines, aromatic amines, and amino alcohols. Claim 3 In paragraph 2, the above-mentioned aliphatic amine is an etching solution having a ratio of carbon atoms (C) to nitrogen atoms (N) in one molecule, C / N, of 4 or more. Claim 4 An etching solution according to any one of claims 1 to 3, wherein the organic acid is at least one selected from acetic acid, acetic anhydride, methoxyacetic acid, ethoxyacetic acid, propionic acid, butanoic acid, citric acid, formic acid, gluconic acid, glycolic acid, malonic acid, oxalic acid, lactic acid, and pentacarbonate. Claim 5 An etching solution according to any one of claims 1 to 4, wherein the amount of the nitrogen-containing compound is 0.01 mass% or more and 5 mass% or less. Claim 6 An etching solution according to any one of claims 1 to 5, wherein the mass ratio (organic acid / nitrogen-containing compound) of the blended amounts of the organic acid and the nitrogen-containing compound is 10 or more and 10,000 or less. Claim 7 An etching solution described in any one of claims 1 to 6, wherein water is additionally mixed in. Claim 8 An etching solution according to any one of claims 1 to 7, wherein the pH of the etching solution is 2 or less. Claim 9 An etching method comprising a process of etching a layer to be etched comprising at least one metal using an etching solution described in any one of claims 1 to 8, wherein the temperature of the etching solution during etching is 20°C or higher and 50°C or lower. Claim 10 An etching solution for etching a layer to be etched comprising at least one type of metal, comprising a salt of a nitrogen-containing compound having a ratio of carbon atoms (C) to nitrogen atoms (N) in one molecule, C / N, of 2.2 or more, and an acid including an organic acid, nitric acid, and phosphoric acid, wherein the amount of organic acid in the etching solution is 50 mass% or more. Claim 11 An etching solution for etching a layer to be etched containing at least one type of metal, comprising a nitrogen-containing compound having a ratio of carbon atoms (C) to nitrogen atoms (N) in one molecule of 2.2 or more and an acid including an organic acid, nitric acid, and phosphoric acid, wherein the amount of organic acid in the etching solution is 80 mass% or more. Claim 12 An etching solution for etching a layer to be etched containing molybdenum, comprising at least one nitrogen-containing compound having a ratio of carbon atoms (C) to nitrogen atoms (N) in one molecule, C / N, of 2.2 or more, and an acid including an organic acid, nitric acid, and phosphoric acid, wherein the amount of organic acid in the etching solution is 50 mass% or more. Claim 13 A method for manufacturing an electronic component comprising a process of etching a layer to be etched comprising at least one metal using an etching solution described in any one of claims 1 to 8, 10, 11 and 12.

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