Etching solution

Abstract

In one aspect, provided is an etching solution which is excellent in storage stability and exerts suppression of etching and improvement in quality of a surface of an etched layer after etching. In one aspect, the present disclosure relates to an etching solution for etching a layer to be etched, wherein: the layer to be etched contains at least one kind of metal; the etching solution is obtained by blending a nitrogen-containing compound, an acid including an organic acid, nitric acid, and phosphoric acid, and water; the ratio C / N between the number (C) of carbon atoms and the number (N) of nitrogen atoms in one molecule of the nitrogen-containing compound is 2.2 or more; and the blending amount of the organic acid in the etching solution is 50% by mass or more.

Description

Etching solution

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

[0002] In the manufacturing process of semiconductor devices, a step is carried out in which a layer to be etched, which contains 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, is etched into a predetermined pattern shape. In the field of semiconductors in recent years, high integration has progressed, and more complex and finer wiring is required. This has led to increasing demands for pattern processing techniques and etching solutions, and various etching methods and etching solutions have been proposed.

[0003] For example, Japanese Patent Laid-Open 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 per molecule, which is used to etch a metal film having at least one layer of a metal thin film of molybdenum or a molybdenum alloy. Japanese Patent Laid-Open No. 2021-114569 (Patent Document 2) proposes a substrate processing method including the steps of: supplying a first etching solution containing an oxidant (e.g., nitric acid), a catalyst (e.g., phosphoric acid), and a moisture adjuster (e.g., an organic acid), in which the proportion of the moisture adjuster is higher than the combined proportion of the oxidant and the catalyst, to a substrate having a laminate film including a molybdenum film; and, after supplying the first etching solution to the substrate, supplying a second etching solution to the substrate, in which the proportion of the moisture adjuster is higher than that of the first etching solution. JP 2022-502835 A (Patent Document 3) proposes an etching solution containing about 65 to 90 wt % phosphoric acid, about 0.01 to 4 wt % acetic acid, 0.01 to 5 wt % nitric acid, and water as an etching solution for selectively etching aluminum oxide, tungsten, and / or titanium nitride.

[0004] In one aspect, the present disclosure relates to an etching solution for etching a layer to be etched that contains at least one metal, the etching solution comprising a nitrogen-containing compound having a ratio C / N of the number of carbon atoms (C) to the number of nitrogen atoms (N) in one molecule of 2.2 or more, an organic acid, and an acid containing nitric acid and phosphoric acid, wherein the amount of the organic acid in the etching solution is 50 mass% or more.

[0005] In one aspect, the present disclosure relates to an etching method including a step of etching a layer to be etched that contains at least one metal using the 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.

[0006] In one aspect, the present disclosure relates to an etching solution for etching a layer to be etched that contains at least one metal, the etching solution comprising a salt of a nitrogen-containing compound having a ratio C / N of the number of carbon atoms (C) to the number of nitrogen atoms (N) in one molecule of 2.2 or more, an organic acid, and an acid containing nitric acid and phosphoric acid, wherein the amount of the organic acid in the etching solution is 50 mass% or more.

[0007] In one aspect, the present disclosure relates to an etching solution for etching a layer to be etched that contains at least one metal, the etching solution comprising a nitrogen-containing compound having a ratio C / N of the number of carbon atoms (C) to the number of nitrogen atoms (N) in one molecule of 2.2 or more, an organic acid, and an acid containing nitric acid and phosphoric acid, wherein the amount of the organic acid in the etching solution is 80 mass% or more.

[0008] In one aspect, the present disclosure relates to an etching solution for etching a layer to be etched that contains molybdenum, the etching solution comprising at least one nitrogen-containing compound having a ratio C / N of the number of carbon atoms (C) to the number of nitrogen atoms (N) in one molecule of 2.2 or more, an organic acid, and an acid containing nitric acid and phosphoric acid, wherein the amount of the organic acid in the etching solution is 50 mass% or more.

[0009] In one aspect, the present disclosure relates to a method for producing an electronic component, comprising a step of etching a layer to be etched that contains at least one metal using the etching solution of the present disclosure.

[0010] As an etching solution, a mixed acid aqueous solution (strong acid aqueous solution) containing phosphoric acid, nitric acid, and an organic acid (e.g., acetic acid) is generally used. Furthermore, a nitrogen-containing compound may be used as an etching inhibitor in the etching solution to prevent deterioration of the quality of the surface of the etched layer (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. However, adding an auxiliary agent such as polyalkylene polyamine to the mixed acid aqueous solution causes turbidity, which leads to a problem of deteriorating the storage stability of the etching solution.

[0011] Therefore, in one aspect, the present disclosure provides an etching solution that has excellent storage stability and can suppress etching and improve the quality of the surface of a layer to be etched after etching, and an etching method using the same.

[0012] As a result of extensive research, the present inventors have found that by using an etching solution containing or blending a specific nitrogen-containing compound and an acid containing 50 mass % or more of an organic acid, it is possible to suppress etching, improve the quality of the surface of the layer to be etched after etching (uniform etching of the layer to be etched), and improve storage stability.

[0013] In one aspect, the present disclosure relates to an etching solution for etching a layer to be etched that contains at least one metal, the etching solution comprising a nitrogen-containing compound having a ratio C / N of the number of carbon atoms (C) to the number of nitrogen atoms (N) in one molecule of 2.2 or more, an organic acid, and an acid containing nitric acid and phosphoric acid, wherein 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").

[0014] According to one aspect of the present disclosure, an etching solution can be provided that has excellent storage stability and is capable of suppressing etching and improving the quality of the surface of a layer to be etched after etching.

[0015] Although the details of the mechanism by which the effects of the present disclosure are manifested are unclear, it is speculated as follows. When a nitrogen-containing compound such as a polyvalent amine is mixed as an etching inhibitor with a mixed acid aqueous solution (strong acid 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 in the mixed acid aqueous solution. In particular, for example, in the case of a polyvalent amine containing many nitrogen atoms, which are hydrophilic groups, in its molecule, a salt of the hydrophilic polyvalent amine and the acid is easily soluble in an aqueous solvent. In the case of a polyvalent amine containing many methylene groups, which are hydrophobic groups, in its molecule, a salt of the hydrophobic polyvalent amine and the acid is difficult to dissolve in an aqueous solvent. On the other hand, in a low-pH mixed acid aqueous solution (strong acid aqueous solution), the organic acid does not dissociate, and the hydrophobicity of the mixed acid aqueous solution increases as the amount of organic acid added increases. Therefore, while a salt of a hydrophobic polyvalent amine and an acid is soluble, the solubility of a salt of a hydrophilic polyvalent amine and an acid is extremely reduced, causing the solution to become cloudy. In the present disclosure, a specific nitrogen-containing compound with high hydrophobicity or amphiphilicity (a nitrogen-containing compound having a ratio C / N of the number of carbon atoms (C) to the number of nitrogen atoms (N) in one molecule of 2.2 or more) is used as an etching inhibitor. Combining this nitrogen-containing compound with a mixed acid containing 50% by mass or more of an organic acid is believed to improve the solubility of the salt of the nitrogen-containing compound and the acid, thereby improving the storage stability of the etching solution. It is also known that the nitrogen-containing compound used as an etching inhibitor acts on the metal surface and inhibits etching by acid. In the present disclosure, a high concentration of organic acid reduces the viscosity of the mixed acid aqueous solution, thereby improving the diffusibility of the acid itself and the nitrogen-containing compound, achieving uniform etching of the surface. In other words, it is believed that etching can be inhibited and the quality of the surface of the etched layer can be improved after etching. However, the present disclosure need not be interpreted as being limited to these mechanisms.

[0016] [Nitrogen-Containing Compound (Component A) Having a Ratio C / N of the Number of Carbons (C) to the Number of Nitrogens (N) in One Molecule of 2.2 or More] The etching solution of the present disclosure contains or is formulated with a nitrogen-containing compound (hereinafter also referred to as "Component A") having a ratio C / N of the number of carbons (C) to the number of nitrogens (N) in one molecule of 2.2 or more. The number of carbons (C) in one molecule of Component A is preferably 4 or more, more preferably 8 or more, from the viewpoints of storage stability and etching inhibition, and is preferably 24 or less, more preferably 18 or less, from the viewpoint of improving the quality of the layer to be etched. From the same viewpoint, the number of carbons in one molecule of Component A is preferably 4 or more and 24 or less, more preferably 8 or more and 18 or less. The number of nitrogens (N) in one molecule of Component A is preferably 1 or more, more preferably 2 or more, from the viewpoints of storage stability and etching inhibition, and is preferably 3 or less, from the viewpoint of improving the quality of the layer to be etched. From the same viewpoint, the number of nitrogens in one molecule of Component A is preferably 1 or more and 3 or less. In one or more embodiments, the ratio C / N of the number of carbon atoms (C) to the number of nitrogen atoms (N) in one molecule of component A is 2.2 or more, preferably 2.3 or more, more preferably 4 or more, and even more preferably 8 or more, from the viewpoint of storage stability and etching inhibition. Also, from the viewpoint of improving the quality of the layer to be etched, it is preferably 20 or less, more preferably 18 or less. More specifically, the ratio C / N of component A is preferably 2.2 or more and 20 or less, more preferably 4 or more and 18 or less, and even more preferably 8 or more and 18 or less. In one or more embodiments, component A contained in or blended with the etching solution of the present disclosure is at least one nitrogen-containing compound selected from aliphatic amines, aromatic amines, and amino alcohols. Component A may be one type or a combination of two or more types.

[0017] 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 a salt with an acid in the etching solution. Therefore, in another aspect, the present disclosure relates to an etching solution for etching a layer to be etched that contains at least one metal, the etching solution comprising a salt of component A and an acid containing an organic acid, nitric acid, and phosphoric acid, wherein the amount of the organic acid in the etching solution is 50 mass% or more.

[0018] (Aliphatic Amine) In one or more embodiments, Component A may be an aliphatic amine. Examples of the aliphatic amine include primary, secondary, and tertiary aliphatic amines. The aliphatic amines may be one type or a combination of two or more types. 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 a compound in which one hydrogen atom of ammonia is substituted with a hydrocarbon group, a secondary aliphatic amine is a compound in which two hydrogen atoms of ammonia are substituted with hydrocarbon groups, and a tertiary aliphatic amine is a compound in which three hydrogen atoms of ammonia are substituted with hydrocarbon groups. Examples of the hydrocarbon group include hydrocarbon groups having from 1 to 24 carbon atoms. The hydrocarbon group may be linear, branched, or cyclic. The hydrocarbon group may contain an unsaturated bond. The hydrocarbon group may be partially substituted with an oxygen atom or the like. The number of carbon atoms in the aliphatic amine is preferably 4 or more, more preferably 8 or more, from the viewpoints of storage stability and etching inhibition, and is preferably 24 or less, more preferably 18 or less, from the viewpoint of improving the quality of the layer to be etched. From the same viewpoint, the number of carbon atoms in 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. The ratio C / N of the number of carbon atoms (C) to the number of nitrogen atoms (N) in one molecule of the aliphatic amine is preferably 4 or more and more preferably 6 or more, from the viewpoint of storage stability, and is preferably 24 or less, more preferably 20 or less, and even more preferably 18 or less, from the viewpoint of improving the quality of the layer to be etched. From the same viewpoint, the ratio C / N of the number of carbon atoms to the number of nitrogen atoms in one molecule of the aliphatic amine is preferably 4 or more and more preferably 6 or more, and is even more preferably 24 or less, more preferably 20 or less, and even more preferably 18 or less.Examples of the 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. Examples of the secondary aliphatic amines include methylhexylamine, methylpentylamine, methyloctylamine, methylnonylamine, methyldecylamine, methylundecylamine, methyldodecylamine, methyloctadecylamine, cyclohexylamine, bis(hexamethylene)triamine, N-butylethylenediamine, etc. Examples of the tertiary aliphatic amine include dimethylbutylamine, dimethylpentylamine, dimethylhexylamine, methylpentylamine, methyloctylamine, methylnonylamine, methyldecylamine, methylundecylamine, methyldodecylamine, dimethyloctadecylamine, etc. In one or more embodiments, the aliphatic amine may be one or more compounds represented by the following formula (I): In the above formula (I), R 1 R is a linear or branched alkyl group having 1 to 18 carbon atoms, a linear or branched 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 contain an amino group or an ether bond. 2 and R 3 are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 8 carbon atoms, a linear or branched 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 contain an amino group or an ether bond. 1R is preferably a linear alkyl group having 1 to 18 carbon atoms, a linear alkyl group having 1 to 18 carbon atoms and containing an amino group, or a branched alkenyl group having 1 to 18 carbon atoms. 2 and R 3 are each independently a hydrogen atom, a methyl group, or a linear alkyl group having 1 to 8 carbon atoms and an amino group.

[0019] (Aromatic Amine) In one or more embodiments, Component A may be an aromatic amine. The aromatic amine may be one type or a combination of two or more types. 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. From the viewpoints of etching suppression and improving the quality of the etched layer, the aromatic amine is preferably a primary aromatic amine in which one hydrogen atom of ammonia is substituted with an aromatic ring. Examples of the aromatic ring include a benzene ring. The aromatic ring may have a substituent. Examples of the substituent include an alkyl group having 1 to 12 carbon atoms. The alkyl group may be either linear or branched. Examples of the branched alkyl group include an isopropyl group. From the viewpoints of etching suppression and storage stability, examples of the aromatic amine include 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.); and the like.

[0020] (Amino Alcohol) In one or more embodiments, component A may be an amino alcohol. The amino alcohol may be one type or a combination of two or more types. In the present disclosure, an amino alcohol (alkanolamine) is a compound having a hydroxyl group and an amino group. Examples of the amino group include primary, secondary, and tertiary amino groups, and from the viewpoints of etching suppression and improving the quality of the etched layer, primary amino groups are preferred. From the viewpoint of storage stability, the number of carbon atoms in the amino alcohol is preferably 2 to 24, more preferably 4 to 18, and even more preferably 4 to 12. Examples of the amino alcohol include 2-(2-aminoethoxy)ethanol and triethanolamine. In one or more embodiments, the amino alcohol (component A) may be one or more compounds represented by the following formula (II): In the above formula (II), R 4 R is a linear or branched alkyl group having 2 to 6 carbon atoms, and the alkyl group may have an ether group. 5 and R 6 are each independently a hydrogen atom or a linear or branched alkyl group having from 2 to 6 carbon atoms, and the alkyl group may have an amino group, a hydroxy group, or an ether group. 4 The alkyl group of R is preferably linear. 4 is preferably a linear alkyl group having 2 to 6 carbon atoms and having an ether group, and R 5 and R 6 are each independently preferably a hydrogen atom.

[0021] In one or more embodiments, from the viewpoint of suppressing etching and improving the quality of the etched layer, Component A is preferably 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 more preferably at least one selected from dodecylamine, octadecylamine, methyloctadecylamine, dimethyloctadecylamine, oleylamine, bis(hexamethylene)triamine, aniline, 2,6-diisopropylaniline, 5-methylbenzotriazole, and 2-(2-aminoethoxy)ethanol.

[0022] The molecular weight of component A contained in the etching solution of the present disclosure is preferably 70 or more, more preferably 120 or more, and even more preferably 150 or more, from the viewpoint of suppressing etching and improving the quality of the layer to be etched, and is preferably 350 or less, preferably 300 or less, and more preferably 250 or less, from the viewpoint of improving the quality of the layer to be etched. 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 even more preferably 150 or more and 250 or less.

[0023] The blending amount of component A in the etching solution of the present disclosure is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.5% by mass or more, from the viewpoint of etching suppression and improving the quality of the etched layer, and from the viewpoint of storage stability, it is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 2% by mass or less. From the same viewpoint, the blending amount of component A in the etching solution of the present disclosure is preferably 0.01% by mass or more and 5% by mass or less, more preferably 0.1% by mass or more and 3% by mass or less, and even more preferably 0.5% by mass or more and 2% by mass or less. When component A is a combination of two or more types, the blending amount of component A is the total blending amount of the two or more types.

[0024] [Acid] The acid contained in or blended into the etching solution of the present disclosure is an acid containing an organic acid, nitric acid, and phosphoric acid. From the viewpoint of storage stability, in one or more embodiments, the acid contained in or blended into the etching solution of the present disclosure may be an acid (mixed acid) consisting of an organic acid, nitric acid, and phosphoric acid. From the viewpoint of etching inhibition and storage stability, the amount of acid blended 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.

[0025] (Organic Acid) From the viewpoint of storage stability, examples of the organic acid include 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 pentanoic acid. Among these, from the same viewpoint, at least one selected from acetic acid, acetic anhydride, methoxyacetic acid, and ethoxyacetic acid is preferred, with acetic acid being more preferred. One organic acid may be used, or two or more organic acids may be used in combination. When acetic anhydride is used as the organic acid in preparing the etching solution of the present disclosure, the acetic anhydride reacts with water in the etching solution to convert it into acetic acid and water, thereby reducing the water content in the etching solution. From the viewpoints of improving the quality and storage stability of the etched layer, and reducing the viscosity of the etching solution, the blending amount of the organic acid in the etching solution of the present disclosure is 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more or 85% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less. More specifically, the amount of organic acid in the etching solution of the present disclosure is preferably 50% by mass or more and 95% by mass or less, more preferably 70% by mass or more and 90% by mass or less, or more preferably 80% by mass or more and 90% by mass or less. When two or more organic acids are used in combination, the amount of organic acid is the total amount of the organic acids. Therefore, in another aspect, the present disclosure relates to an etching solution for etching a layer to be etched that contains at least one metal, the etching solution comprising component A and an acid containing an organic acid, nitric acid, and phosphoric acid, and the amount of organic acid in the etching solution is 80% by mass or more.

[0026] (Nitric Acid) From the viewpoint of improving the quality of the layer to be etched, the amount of nitric acid in the etching solution of the present disclosure is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, and from the viewpoint of improving the quality of the layer to be etched and storage stability, it is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less. More specifically, the amount of nitric acid in the etching solution of the present disclosure is preferably 0.1% by mass or more and 10% by mass or less, more preferably 0.5% by mass or more and 8% by mass or less, and even more preferably 1% by mass or more and 5% by mass or less.

[0027] (Phosphoric Acid) From the viewpoint of improving the quality of the layer to be etched, the amount of phosphoric acid in the etching solution of the present disclosure is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, and from the viewpoint of improving the quality of the layer to be etched and storage stability, the amount is preferably 40% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less. More specifically, the amount of phosphoric acid in the etching solution of the present disclosure is preferably 0.1% by mass or more and 40% by mass or less, more preferably 0.5% by mass or more and 20% by mass or less, and even more preferably 1% by mass or more and 10% by mass or less.

[0028] The mass ratio of the organic acid to the phosphoric acid (organic acid / phosphoric acid) in the etching solution of the present disclosure is preferably 1.2 or more, more preferably 3.5 or more, 5 or more, or 6 or more, from the viewpoint of etching inhibition, and similarly from the viewpoint of etching inhibition, is preferably 950 or less, more preferably 100 or less, 50 or less, or 20 or less. More specifically, the mass ratio (organic acid / phosphoric acid) in the etching solution of the present disclosure is preferably 1.2 or more and 950 or less, 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.

[0029] The mass ratio (organic acid / nitrogen-containing compound) of the amount of the organic acid to the amount of the nitrogen-containing compound (component A) in the etching solution of the present disclosure is preferably 10 or more, more preferably 20 or more, even more preferably 30 or more, still more preferably 40 or more, and even more preferably 50 or more, from the viewpoints of etching suppression and reducing the viscosity of the etching solution, and from the same viewpoints, is preferably 10,000 or less, more preferably 5,000 or less, even more preferably 2,500 or less, still more preferably 1,000 or less, still more preferably 500 or less, and even more preferably 100 or less. More specifically, the mass ratio (organic acid / nitrogen-containing compound) in the etching solution of the present disclosure 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, still more preferably 40 or more and 1,000 or less, still more preferably 50 or more and 500 or less, and even more preferably 50 or more and 100 or less.

[0030] (Other Acids) The acid contained in or blended into the etching solution of the present disclosure may further contain an acid other than nitric acid, phosphoric acid, and organic acid. Examples of other acids include inorganic acids other than nitric acid and phosphoric acid. Examples of inorganic acids include hydrochloric acid, sulfuric acid, and hydrofluoric acid.

[0031] [Water] In one or more embodiments, the etching solution of the present disclosure further contains or is blended with water. Examples of water contained in or blended with the etching solution of the present disclosure include distilled water, ion-exchanged water, pure water, and ultrapure water.

[0032] The blending amount of water in the etching solution of the present disclosure is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less, from the viewpoint of improving the quality of the layer to be etched.

[0033] [Other Components] The etching solution of the present disclosure may further contain other components within the scope that does not impair the effects of the present disclosure. Examples of other components include chelating agents, surfactants, solubilizing agents, preservatives, rust inhibitors, disinfectants, antibacterial agents, antioxidants, etc.

[0034] In one or more embodiments, the etching solution of the present disclosure may be substantially free of polyalkyleneimine and polyalkylenepolyamine. Examples of the polyalkyleneimine include polyethyleneimine. Examples of the polyalkylenepolyamine include polyalkylenepolyamines containing three or more amino groups per molecule, such as triethylenetetramine. The content of polyalkyleneimine and polyalkylenepolyamine in the etching solution of the present disclosure is preferably less than 0.01% by mass, more preferably 0.001% by mass or less, and even more preferably 0% by mass (i.e., no polyalkyleneimine or polyalkylenepolyamine).

[0035] [Method for Producing Etching Solution] In one aspect, the etching solution of the present disclosure is obtained by blending component A, an acid containing an organic acid, nitric acid, and phosphoric acid, water, and, if desired, the optional components described above, using a known method. Therefore, in one aspect, the present disclosure relates to a method for producing an etching solution (hereinafter also referred to as the "etching solution production method of the present disclosure") that includes blending at least component A, an organic acid, nitric acid, phosphoric acid, and water. In one or more embodiments, the phrase "blending at least component A, an organic acid, nitric acid, phosphoric acid, and water" in the present disclosure includes simultaneously or sequentially mixing component A, the organic acid, nitric acid, phosphoric acid, water, and, if necessary, the optional components described above. The order of mixing is not particularly limited. The blending can be performed using a mixer such as a propeller-type agitator, a pump-based liquid circulation agitator, a homomixer, a homogenizer, an ultrasonic disperser, or a wet ball mill. The preferred amounts of each component in the etching solution production method of the present disclosure may be the same as the preferred amounts of each component in the etching solution of the present disclosure described above.

[0036] In the present disclosure, the "amount of each component in the etching solution" refers, in one or more embodiments, to the amount of each component used in the etching step, i.e., the amount of each component in the etching solution at the time of starting use in the etching process (at the time of use). In one or more embodiments, the amount of each component in the etching solution of the present disclosure can be considered to be the content of each component in the etching solution of the present disclosure. However, if there is an effect of neutralization, the amount of each component may differ from the content.

[0037] An embodiment of the etching solution of the present disclosure may be a so-called one-component type, in which all components are supplied to the market in a pre-mixed state, or a so-called two-component type, in which components are mixed at the time of use. One embodiment of a two-component etching solution is one that is composed of a solution containing component A (first component) and an acid aqueous solution containing an organic acid, nitric acid, and phosphoric acid (second component), and the first and second components are mixed at the time of use. After the first and second components are mixed, they may be diluted with water or an acid aqueous solution as needed. The first or second component may contain all or a portion of the water used to prepare the etching solution. The first and second components may each contain the optional components described above as needed.

[0038] From the viewpoint of storage stability, the pH of the etching solution of the present disclosure is preferably 2 or less, and more preferably 1 or less. The pH of the etching solution of the present disclosure can be preferably −2.5 or more, and more preferably −2 or more. In the present disclosure, the pH of the etching solution is a value at 25° C., and can be measured using a pH meter, specifically, by the method described in the Examples.

[0039] 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 viewpoint of improving the quality of the layer to be etched. Also, from the viewpoint of improving the quality of the layer to be etched, the viscosity 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, 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 Brookfield viscometer or an Ubbelohde 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, with water or an organic solvent.

[0040] The etching solution of the present disclosure may be stored and supplied in a concentrated state as long as its stability is not impaired. This is preferable because it reduces production and transportation costs. The concentrated solution can then be diluted appropriately with water or an aqueous acid solution as needed for use in the etching process. The dilution ratio can be, for example, 5 to 100 times.

[0041] [Kit] In another aspect, the present disclosure relates to a kit for producing the etching solution of the present disclosure (hereinafter also referred to as the "kit of the present disclosure"). Examples of the kit of the present disclosure include a kit (two-component etching solution) that contains a solution containing component A (first liquid) and an acid aqueous solution (second liquid) containing an organic acid, nitric acid, and phosphoric acid in a mutually unmixed state, and that is mixed at the time of use. After the first liquid and the second liquid are mixed, they may be diluted with water or an acid aqueous solution as needed. The first liquid or the second liquid may contain all or a portion of the water used to prepare the etching solution. The first liquid and the second liquid may each contain the optional components described above as needed. The kit of the present disclosure allows the preparation of an etching solution with excellent storage stability.

[0042] [Layer to be etched] In one or more embodiments, the layer to be etched using the etching solution of the present disclosure is a layer to be etched containing at least one metal. Here, the metal is not particularly limited as long as the effects of the present disclosure are achieved, but examples thereof include 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. Among these, in one or more embodiments, the etching solution of the present disclosure is preferably used to etch a layer to be etched containing at least one metal selected from tungsten, molybdenum, niobium, tantalum, and zirconium, and in one or more embodiments, is preferably used to etch a molybdenum film. That is, in one or more embodiments, the layer to be etched is a molybdenum film. Therefore, in another aspect, the present disclosure relates to an etching solution for etching a layer to be etched that contains molybdenum, the etching solution comprising Component A and an organic acid, and an acid containing nitric acid and phosphoric acid, wherein the amount of the organic acid in the etching solution is 50 mass% or more. In one or more embodiments, the layer to be etched is a layer to be etched formed on a substrate. Examples of the substrate include 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 an FED (Field Emission Display), a substrate for an optical disk, a substrate for a magnetic disk, a substrate for a magneto-optical disk, a substrate for a photomask, a ceramic substrate, and a substrate for a solar cell.

[0043] [Etching Method] In one aspect, the present disclosure relates to an etching method (hereinafter also referred to as the "etching method of the present disclosure") that includes a step of etching a layer to be etched that contains at least one metal using the etching solution of the present disclosure (hereinafter also referred to as the "etching step of the present disclosure"), in which 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 semiconductor substrates can be improved by using an etching solution that has excellent storage stability.

[0044] In the etching step of the present disclosure, examples of the etching method include immersion etching and single wafer etching.

[0045] The temperature of the etching solution during etching in the etching step of the present disclosure (etching temperature) is preferably 20° C. or higher, more preferably 25° C. or higher, and even more preferably 30° C. or higher, from the viewpoint of improving the quality of the layer to be etched, and is preferably 50° C. or lower, more preferably 45° C. or lower, and even more preferably 40° C. or lower, from the viewpoint of improving the quality of the layer to be etched. 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 even more preferably 30° C. or higher and 40° C. or lower.

[0046] In the etching step of the present disclosure, the etching time can be set to, for example, 1 minute or more and 180 minutes or less. From the viewpoint of improving the quality of the etched layer, it is preferably 15 minutes or more and 90 minutes or less, more preferably 30 minutes or more and 60 minutes or less.

[0047] In one or more embodiments, the etching solution and etching method of the present disclosure can be used to etch metals in the manufacturing process of electronic devices, particularly semiconductor wafers (semiconductor substrates). Examples of metals include those described above. In one or more embodiments, the etching solution and etching method of the present disclosure can be suitably used in the manufacture of at least one substrate selected from semiconductor wafers (semiconductor substrates), substrates for liquid crystal displays, substrates for plasma displays, substrates for field emission displays (FEDs), substrates for optical disks, substrates for magnetic disks, substrates for magneto-optical disks, substrates for photomasks, ceramic substrates, and substrates for solar cells. This enables uniform etching of the layer to be etched, improving productivity and yield. In one or more embodiments, the etching solution and etching method of the present disclosure can be used to etch electrodes in the manufacturing process of electronic devices, particularly semiconductor memories such as nonvolatile memories including NAND flash memories. In one or more embodiments, the etching solution and etching method of the present disclosure can be suitably used in the manufacture of patterns having three-dimensional structures. This allows for the production of advanced devices such as high-capacity memories. The etching solution and the etching method of the present disclosure can be used, for example, in an etching method such as that disclosed in JP 2020-145412 A.

[0048] [Method for Manufacturing Electronic Components] In one aspect, the present disclosure relates to a method for manufacturing electronic components (hereinafter also referred to as the "electronic component manufacturing method of the present disclosure"), which includes a step (etching step) of etching a layer to be etched containing at least one metal using the etching solution of the present disclosure. Examples of electronic components include at least one substrate selected from semiconductor wafers (semiconductor substrates), substrates for liquid crystal displays, substrates for plasma displays, substrates for FEDs (Field Emission Displays), substrates for optical disks, substrates for magnetic disks, substrates for magneto-optical disks, substrates for photomasks, ceramic substrates, and substrates for solar cells; semiconductor memories such as nonvolatile memories including NAND flash memories; and the like. The etching method and etching conditions for the etching step of the electronic component manufacturing method of the present disclosure include the same etching method and etching conditions as those for the etching step of the etching method of the present disclosure described above. Examples of the layer to be etched include the above-mentioned layers to be etched.

[0049] The present disclosure further relates to one or more of the following embodiments: <1> An etching solution for etching a layer to be etched that contains at least one metal, comprising: a nitrogen-containing compound having a ratio C / N of the number of carbon atoms (C) to the number of 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 the organic acid in the etching solution is 50% by mass or more. <2> An etching solution for etching a layer to be etched that contains at least one metal, comprising: a salt of a nitrogen-containing compound having a ratio C / N of the number of carbon atoms (C) to the number of 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 the organic acid in the etching solution is 50% by mass or more. <3> An etching solution for etching a layer to be etched that contains at least one metal, comprising: a nitrogen-containing compound having a ratio C / N of the number of carbon atoms (C) to the number of nitrogen atoms (N) in one molecule of 2.2 or more; and an acid including nitric acid and phosphoric acid, wherein the amount of the organic acid in the etching solution is 80% by mass or more. <4> An etching solution for etching a layer to be etched that contains molybdenum, comprising: at least one nitrogen-containing compound having a ratio C / N of the number of carbon atoms (C) to the number of nitrogen atoms (N) in one molecule of 2.2 or more; and an acid including organic acid, nitric acid, and phosphoric acid, wherein the amount of the organic acid in the etching solution is 50% by mass or more. <5> The etching solution according to any one of <1> to <4>, wherein the nitrogen-containing compound is at least one selected from the group consisting of an aliphatic amine, an aromatic amine, and an amino alcohol. <6> The etching solution according to <5>, wherein the aliphatic amine has a ratio C / N of the number of carbon atoms (C) to the number of nitrogen atoms (N) in one molecule of at least 4. <7> The etching solution according to any one of <1> to <6>, wherein the nitrogen-containing compound is a primary, secondary, or tertiary aliphatic amine.<8> The etching solution according to <7>, wherein the 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. <9> The etching solution according to <7> or <8>, wherein the secondary aliphatic amine is one or more selected from methylhexylamine, methylpentylamine, methyloctylamine, methylnonylamine, methyldecylamine, methylundecylamine, methyldodecylamine, methyloctadecylamine, cyclohexylamine, bis(hexamethylene)triamine, and N-butylethylenediamine. <10> The etching solution according to any one of <7> to <9>, wherein the tertiary aliphatic amine is one or more selected from the group consisting of dimethylbutylamine, dimethylpentylamine, dimethylhexylamine, methylpentylamine, methyloctylamine, methylnonylamine, methyldecylamine, methylundecylamine, methyldodecylamine, and dimethyloctadecylamine. <11> The etching solution according to any one of <5> to <10>, wherein the aliphatic amine is one or more compounds represented by the following formula (I): In the above formula (I), R 1 R is a linear or branched alkyl group having 1 to 18 carbon atoms, a linear or branched 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 contain an amino group or an ether bond. 2 and R 3are each independently a hydrogen atom, a linear or branched alkyl group having from 1 to 8 carbon atoms, a linear or branched alkenyl group having from 1 to 8 carbon atoms, or a cyclic hydrocarbon group having from 1 to 8 carbon atoms, and the alkyl group, the alkenyl group, and the cyclic hydrocarbon group may contain an amino group or an ether bond. <12> The etching solution according to any one of <5> to <11>, wherein the aromatic amine is one or more selected from the group consisting of 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.). <13> The etching solution according to any one of <5> to <12>, wherein the amino alcohol is one or more compounds represented by the following formula (II): In the above formula (II), R 4 R is a linear or branched alkyl group having 2 to 6 carbon atoms, and the alkyl group may have an ether group. 5 and R 6are each independently a hydrogen atom or a linear or branched alkyl group having from 2 to 6 carbon atoms, and the alkyl group may have an amino group, a hydroxy group, or an ether group. <14> The etching solution according to any one of <1> to <13>, 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 pentanoic acid. <15> The etching solution according to any one of <1> to <14>, wherein the amount of the nitrogen-containing compound is 0.01% by mass to 5% by mass, or 0.1% by mass to 3% by mass, or 0.5% by mass to 2% by mass. <16> The etching solution according to any one of <1> to <15>, wherein the amount or content of the organic acid is 50% by mass to 95% by mass, or 70% by mass to 90% by mass. <17> The etching solution according to any one of <1> to <16>, wherein the amount or content of the nitric acid is 0.1% by mass to 10% by mass, or 0.5% by mass to 8% by mass, or 1% by mass to 5% by mass. <18> The etching solution according to any one of <1> to <17>, wherein the amount or content of the phosphoric acid is 0.1% by mass to 40% by mass, or 0.5% by mass to 20% by mass, or 1% by mass to 10% by mass. <19> The etching solution according to any one of <1> to <18>, wherein the mass ratio of the amount or content of the organic acid to the phosphoric acid (organic acid / phosphoric acid) is 1.2 to 950, or 3.5 to 100, or 5 to 50, or 6 to 20. <20> The etching solution according to any one of <1> to <19>, wherein the mass ratio of the blending amounts or contents of the organic acid and the 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. <21> The etching solution according to any one of <1> to <20>, further comprising water. <22> The etching solution according to any one of <1> to <21>, wherein the pH of the etching solution is 2 or less, or 1 or less.<23> The etching solution according to any one of <1> to <22>, wherein the pH of the etching solution is -2.5 or higher, or -2 or higher. <24> The etching solution according to any one of <1> to <23>, wherein the viscosity of the etching solution at 25°C is 1 mPa·s or higher and 25 mPa·s or lower, or 2 mPa·s or higher and 10 mPa·s or lower. <25> An etching method, comprising a step of etching a layer to be etched containing at least one metal using the etching solution according to any one of <1> to <24>, wherein the temperature of the etching solution during etching is 20°C or higher and 50°C or lower. <26> An etching solution for etching a layer to be etched that contains at least one kind of metal, the etching solution comprising: a nitrogen-containing compound having a ratio C / N of the number of carbon atoms (C) to the number of 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 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; the amount of the organic acid in the etching solution is 50% by mass or more; and the mass ratio (organic acid / nitrogen-containing compound) of the amounts of the organic acid and the nitrogen-containing compound in the etching solution is 10 or more and 10,000 or less. <27> A method for producing an electronic component, comprising a step of etching a layer to be etched, the layer containing at least one metal, using the etching solution according to any one of <1> to <24> and <26>.

[0050] The present disclosure will be specifically described below using examples, but the present disclosure is not limited to these examples in any way.

[0051] 1. Preparation of Etching Solutions (Examples 1 to 15, Comparative Examples 1 to 9) Etching solutions (pH: -2.0 to -1.5) of Examples 1 to 15 and Comparative Examples 1 to 9 were obtained by blending nitric acid, phosphoric acid, acetic acid, the nitrogen-containing compound, and water shown in Table 1. The blending amount of each component (mass %, active ingredient) is shown in Table 1. The blending amount of water is the remainder excluding the acid and the nitrogen-containing compound. The blending amount of water also includes the blending amount of water contained in the acid aqueous solution, etc.

[0052] The following components were used to prepare the etching solution. <Acid> Acetic acid [FUJIFILM Wako Pure Chemical Industries, Ltd., concentration 100%] Nitric acid [FUJIFILM Wako Pure Chemical Industries, Ltd., concentration 70%] Phosphoric acid [Rin Kagaku Kogyo Co., Ltd., concentration 85%] <Nitrogen-containing compounds> (Aliphatic amines) Butylamine [Tokyo Chemical Industry Co., Ltd.] Octylamine [Tokyo Chemical Industry Co., Ltd.] Dodecylamine [Tokyo Chemical Industry Co., Ltd.] Octadecylamine [Tokyo Chemical Industry Co., Ltd.] Methyloctadecylamine [Tokyo Chemical Industry Co., Ltd.] Dimethyloctadecylamine [Tokyo Chemical Industry Co., Ltd.] Oleylamine [Tokyo Chemical Industry Co., Ltd.] 2-Ethylhexylamine [Tokyo Chemical Industry Co., Ltd.] Bis(hexamethylene)triamine [Tokyo Chemical Industry Co., Ltd.] (Aromatic amines) Aniline [Tokyo Chemical Industry Co., Ltd.] 2,6-Diisopropylaniline [Tokyo Chemical Industry Co., Ltd.] 5-Methylbenzotriazole [Tokyo Chemical Industry Co., Ltd.] (Amino alcohols) 2-(2-aminoethoxy)ethanol [Tokyo Chemical Industry Co., Ltd.] (phenols) Catechol [Tokyo Chemical Industry Co., Ltd.] (polyalkylenepolyamine) Triethylenetetramine [molecular weight 146.23, Tosoh Corporation] (polyalkyleneimine) Polyethyleneimine (PEI) [number average molecular weight 1,800, "Epomin SP-018" manufactured by Nippon Shokubai Co., Ltd.] <Water> Water [ultrapure water produced using a continuous pure water production system (PureConti PC-2000VRL type) and subsystem (Macace KC-05H type) manufactured by Kurita Water Industries Ltd.]

[0053] [pH of Etching Solution] The pH value of the etching solution at 25° C. was measured using a pH meter (manufactured by DKK-Toa Corporation), and was the value measured one minute after the electrode of the pH meter was immersed in the etching solution.

[0054] [Viscosity of Etching Solution] The viscosity of the etching solution (unit: mPa s) was measured using the following viscometer under the following conditions: Device name: TVB-10 viscometer (with thermostatic bath) manufactured by Toki Sangyo Co., Ltd. Rotor: Spindle No. M1, Cord No. 20 Rotation speed: 100 rpm, viscosity value measured after 60 seconds Measurement temperature: 25°C The viscosity was measured 30 minutes after the temperature inside the thermostatic bath, as displayed by the device, reached 25°C.

[0055] 2. Evaluation of Etching Solution [Solubility (Storage Stability)] The mixed acid and nitrogen-containing compound shown in Table 1 were mixed in the blending amounts (mass %) shown in Table 1 to prepare 20 mL of etching solution. After stirring for 10 minutes, the solubility was confirmed visually. The evaluation criteria for solubility were as follows: A: no residual solution and the etching solution was colorless, transparent, or pale yellowish transparent in the temperature range of 0°C to 40°C; B: some residual solution but the etching solution was colorless, transparent, or pale yellowish transparent in the temperature range of 0°C to 40°C; and C: the etching solution was cloudy or in another state (for example, turned black) in the temperature range of 0°C to 40°C. Any special notes are also listed in the same column.

[0056] [Evaluation of Etching Inhibition Rate] Taking a specific etching solution as an example, the etching rate of the mixed acid alone that constitutes the etching solution is α, and the etching rate of the etching solution in which the mixed acid and a nitrogen-containing compound are mixed is β. The etching inhibition rate is calculated using the following formula. The results are shown in Table 1. Etching inhibition rate (%) = 100 × (α - β) / α

[0057] [Substrate Surface Condition] A molybdenum plate measuring 2 cm in length, 2 cm in width, and 0.1 mm in thickness, the weight of which had been measured in advance, was immersed in the etching solutions (Examples 1 to 15 and Comparative Examples 1 to 5 and 9) prepared to the compositions shown in Table 1, and the molybdenum plate was etched at each temperature and treatment time. However, etching solutions containing a mixed acid alone and a nitrogen-containing compound were tested under the same etching conditions. After rinsing with water, the surface of the molybdenum plate was again observed using a KEYENCE VK-9710 shape-measuring laser microscope (lens magnification: 150x), and photographs were analyzed using the same instrument's surface roughness mode. Surface roughness, an index of etching unevenness, was then calculated using the following formula. Evaluation of etching unevenness of the molybdenum plate was performed based on the following evaluation criteria. The results are shown in Table 1. Surface precision (%) = surface roughness after etching / surface roughness before etching × 100 <Evaluation criteria> 4: Surface precision less than 150% 3: Surface precision 150% or more and less than 200% 2: Surface precision 200% or more and less than 300% 1: Surface precision 300% or more

[0058]

[0059] As shown in Table 1, all of the etching solutions of Examples 1 to 15, which contained a nitrogen-containing compound with a C / N ratio of 2.2 or more as the nitrogen-containing compound, exhibited better solubility and storage stability than the etching solution of Comparative Example 6, which contained catechol (a phenol) instead of the nitrogen-containing compound, and the etching solutions of Comparative Examples 7 and 8, which contained a nitrogen-containing compound with a C / N ratio of less than 2.2 as the nitrogen-containing compound. Furthermore, the etching solutions of Examples 1 to 15, which contained a nitrogen-containing compound with a C / N ratio of 2.2 or more and had 50% or more acetic acid by mass, exhibited superior etching inhibition and better substrate surface conditions than the etching solutions of Comparative Examples 2 to 4, which contained 50% or more acetic acid by mass and no nitrogen-containing compound, and Comparative Example 5, which contained 30% acetic acid by mass and no nitrogen-containing compound. Furthermore, the etching solution of Comparative Example 9, which contained less than 50% acetic acid by mass, exhibited inferior substrate surface conditions than Examples 1, 8, and 15, which contained 50% or more acetic acid by mass.

[0060] The etching solution of the present disclosure has excellent storage stability, and is capable of suppressing etching and improving the quality of the surface of the layer to be etched after etching, and is therefore useful in methods for manufacturing large-capacity semiconductor memories.

Claims

1. An etching solution for etching an etching layer containing at least one kind of metal, which is prepared by blending: a nitrogen-containing compound in which the ratio C / N of the number of carbon atoms (C) to the number of nitrogen atoms (N) in one molecule is 2.2 or more; and an acid containing an organic acid, nitric acid, and phosphoric acid, wherein the blending amount of the organic acid in the etching solution is 50% by mass or more.

2. The etching solution according to claim 1, wherein the nitrogen-containing compound is at least one selected from aliphatic amines, aromatic amines, and amino alcohols.

3. The etching solution according to claim 2, wherein the aliphatic amine has a ratio C / N of the number of carbon atoms (C) to the number of nitrogen atoms (N) in one molecule of 4 or more.

4. The 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 pentanoic acid.

5. The etching solution according to any one of claims 1 to 4, wherein the blending amount of the nitrogen-containing compound is 0.01% by mass or more and 5% by mass or less.

6. The etching solution according to any one of claims 1 to 5, wherein the mass ratio (organic acid / nitrogen-containing compound) of the blending amounts of the organic acid and the nitrogen-containing compound is 10 or more and 10,000 or less.

7. The etching solution according to any one of claims 1 to 6, further blended with water.

8. The etching solution according to any one of claims 1 to 7, wherein the pH of the etching solution is 2 or less.

9. An etching method including a step of etching an etching layer containing at least one kind of metal using the etching solution according to any one of claims 1 to 8, wherein the temperature of the etching solution during etching is 20°C or more and 50°C or less.

10. An etching solution for etching an etching layer containing at least one kind of metal, which contains: a salt of a nitrogen-containing compound in which the ratio C / N of the number of carbon atoms (C) to the number of nitrogen atoms (N) in one molecule is 2.2 or more; and an acid containing an organic acid, nitric acid, and phosphoric acid, wherein the blending amount of the organic acid in the etching solution is 50% by mass or more.

11. An etching solution for etching an etching layer containing at least one metal, comprising: a nitrogen-containing compound having a ratio C / N of the number of carbon atoms (C) to the number of nitrogen atoms (N) in one molecule of 2.2 or more; and an acid containing an organic acid, nitric acid, and phosphoric acid, wherein the amount of the organic acid in the etching solution is 80% by mass or more.

12. An etching solution for etching an etching layer containing molybdenum, comprising: at least one nitrogen-containing compound having a ratio C / N of the number of carbon atoms (C) to the number of nitrogen atoms (N) in one molecule of 2.2 or more; and an acid containing an organic acid, nitric acid, and phosphoric acid, wherein the amount of the organic acid in the etching solution is 50% by mass or more.

13. A method for manufacturing an electronic component, comprising a step of etching an etching layer containing at least one metal using the etching solution according to any one of claims 1 to 8, 10, 11, and 12.

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