Etching solution

Abstract

To provide etching solution that has excellent storage stability and being capable of suppressing etching and improving quality of a surface of a layer to be etched after etching.SOLUTION: Etching solution for etching a layer to be etched containing at least one kind of a metal is obtained by blending 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 acid containing organic acid, nitric acid, and phosphoric acid, and water. A blending amount of the organic acid in the etching solution is 50% by mass or more.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] In the manufacturing process of semiconductor devices, for example, a step of etching an etched layer containing 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 to process it into a predetermined pattern shape is performed. In recent years, in the semiconductor field, high integration has been progressing, and the wiring has become more complex and finer. The requirements for pattern processing technology and etching solutions are also increasing, and various etching methods and etching solutions have been proposed (Patent Documents 1 to 3).

[0003] For example, in Patent Document 1, 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, has been proposed. In Patent Document 2, a first etching solution containing an oxidizing agent (for example, nitric acid), a catalyst (for example, phosphoric acid), and a moisture adjuster (for example, an organic acid), and having a ratio of the moisture adjuster larger than the total ratio of the oxidizing agent and the catalyst, is supplied to a substrate having a laminated film including a molybdenum film. After supplying the first etching solution to the substrate, a step of supplying a second etching solution having a ratio of the moisture adjuster larger than that of the first etching solution to the substrate is included, and a substrate processing method has been proposed. In Patent Document 3, an etching solution containing about 65 to 90% by weight of phosphoric acid, about 0.01 to 4% by weight of acetic acid, 0.01 to 5% by weight of nitric acid, and water has been proposed as an etching solution for selectively etching aluminum oxide, tungsten, and / or titanium nitride.

Prior Art Documents

Patent Document

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] As an etching solution, a mixed acid aqueous solution (strongly acidic aqueous solution) containing phosphoric acid, nitric acid, and an organic acid (for example, acetic acid) is generally used. In addition, a nitrogen-containing compound may be used as an etching inhibitor in the etching solution for reasons such as not deteriorating the quality of the surface of the etched layer (metal film surface) after etching. In Patent Document 1, it is proposed to add a polyalkylene polyamine to an etching solution that does not contain acetic acid as an essential component. However, when an auxiliary agent such as a polyalkylene polyamine is added to the mixed acid aqueous solution, turbidity occurs, and there is a problem that the storage stability of the etching solution deteriorates.

[0006] Therefore, in one aspect, the present disclosure provides an etching solution having excellent storage stability and capable of suppressing etching and improving the quality of the surface of the etched layer after etching, and an etching method using the same.

Means for Solving the Problems

[0007] In one aspect, the present disclosure relates to an etching solution for etching an etched layer containing at least one kind of metal, which is prepared by mixing 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 acid containing an organic acid, nitric acid, and phosphoric acid, and the content of the organic acid in the etching solution is 50% by mass or more.

[0008] In one aspect, the present disclosure relates to an etching method including a step of etching an etching target layer containing 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.

[0009] In one aspect, the present disclosure relates to an etching solution for etching an etching target layer containing at least one metal, the etching solution containing 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.

[0010] In one aspect, the present disclosure relates to an etching solution for etching an etching target layer containing at least one metal, the etching solution being 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 80% by mass or more.

[0011] In one aspect, the present disclosure relates to an etching solution for etching an etching target layer containing molybdenum, the etching solution being prepared by blending at least one 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.

[0012] In one aspect, the present disclosure relates to a method for manufacturing an electronic component, including a step of etching an etching target layer containing at least one metal using the etching solution of the present disclosure.

Advantages of the Invention

[0013] According to the present disclosure, in one aspect, an etching solution having excellent storage stability and capable of suppressing etching and improving the quality of the surface of the etching target layer after etching can be provided.

Embodiments for Carrying Out the Invention

[0014] As a result of intensive studies by the present inventors, by using an etching solution containing or formulated with a specific nitrogen-containing compound and an acid containing 50% by mass or more of an organic acid, it has been found that it is possible to improve the storage stability while exhibiting etching suppression and improvement in the quality of the surface of the layer to be etched after etching (uniform etching of the layer to be etched).

[0015] In one aspect, the present disclosure relates to an etching solution for etching an etching target layer containing at least one metal, the etching solution being formulated with 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 blending amount of the organic acid in the etching solution is 50% by mass or more (hereinafter, also referred to as "the etching solution of the present disclosure").

[0016] Although the details of the mechanism of the expression of the effects of the present disclosure are not clear, it is presumed as follows. 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 (for example, acetic acid), which is generally 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 the molecule, the salt of the hydrophilic polyvalent amine and the acid is easily dissolved in an aqueous solvent. In the case of a polyvalent amine containing many methylene groups, which are hydrophobic groups, in the molecule, the salt of the hydrophobic polyvalent amine and the acid is hardly dissolved in an aqueous solvent. On the other hand, in a mixed acid aqueous solution (strongly acidic aqueous solution) with a low pH, the organic acid is not dissociated, and as the blending amount of the organic acid increases, the hydrophobicity of the mixed acid aqueous solution increases. Therefore, although the salt of the hydrophobic polyvalent amine and the acid can be dissolved, the solubility of the salt of the hydrophilic polyvalent amine and the acid extremely decreases and becomes cloudy. In the present disclosure, as an etching inhibitor, a specific nitrogen-containing compound having high hydrophobicity or amphiphilicity (a nitrogen-containing compound having a carbon number (C) to nitrogen number (N) ratio C / N of 2.2 or more in one molecule) is used, and by combining this nitrogen-containing compound with a mixed acid containing 50% by mass or more of an organic acid, it is considered that the solubility of the salt of the nitrogen-containing compound and the acid can be improved, and the storage stability of the etching solution can be improved. Also, it is known that a nitrogen-containing compound used as an etching inhibitor acts on the metal surface and suppresses etching by an acid. In the present disclosure, since a high-concentration organic acid reduces the viscosity of the mixed acid aqueous solution, the diffusibility of the acid itself and the nitrogen-containing compound is improved, and uniform etching of the surface is achieved, that is, it is considered that etching suppression and improvement in the quality of the surface of the etched layer after etching can be demonstrated. However, the present disclosure may not be construed as being limited to these mechanisms.

[0017] [A nitrogen-containing compound (component A) having a carbon number (C) to nitrogen number (N) ratio C / N of 2.2 or more in one molecule] 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 carbon number (C) to nitrogen number (N) ratio C / N of 2.2 or more in one molecule. From the viewpoints of storage stability and etching suppression, the carbon number (C) in one molecule of component A is preferably 4 or more, more preferably 8 or more, and from the viewpoint of improving the quality of the etched layer, it is preferably 24 or less, more preferably 18 or less. From the same viewpoints, the carbon number in one molecule of component A is preferably 4 or more and 24 or less, more preferably 8 or more and 18 or less. From the viewpoints of storage stability and etching suppression, the nitrogen number (N) in one molecule of component A is preferably 1 or more, more preferably 2 or more, and from the viewpoint of improving the quality of the etched layer, it is preferably 3 or less. From the same viewpoints, the nitrogen number in one molecule of component A is preferably 1 or more and 3 or less. In one or more embodiments, the ratio 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, still more preferably 8 or more, from the viewpoints of storage stability and etching suppression. 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, still more preferably 8 or more and 18 or less. In one or more embodiments, Component A contained or blended in 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 kind or a combination of two or more kinds.

[0018] 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 can form a salt with an acid in the etching solution. Therefore, in other aspects, the present disclosure relates to an etching solution for etching an etching target layer containing at least one metal, the etching solution containing a salt of Component A and an acid containing an organic acid, nitric acid, and phosphoric acid, and the blending amount of the organic acid in the etching solution being 50% by mass or more.

[0019] (Aliphatic amine) In one or more embodiments, Component A includes aliphatic amines. Examples of the aliphatic amine include primary, secondary, or tertiary aliphatic amines. The aliphatic amine may be one kind or a combination of two or more kinds. 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 hydrocarbon groups, and a tertiary aliphatic amine is one in which three hydrogen atoms of ammonia are substituted with hydrocarbon groups. Examples of the hydrocarbon group include hydrocarbon groups having 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. From the viewpoints of storage stability and etching suppression, the number of carbon atoms of the aliphatic amine is preferably 4 or more, more preferably 8 or more, and from the viewpoint of improving the quality of the layer to be etched, it is preferably 24 or less, more preferably 18 or less. From the same viewpoints, the number of carbon atoms of the primary, secondary, or tertiary aliphatic amine is preferably 4 to 24, more preferably 8 to 18. From the viewpoint of storage stability, 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, more preferably 6 or more, and from the viewpoint of improving the quality of the layer to be etched, it is preferably 24 or less, more preferably 20 or less, and even more preferably 18 or less. From the same viewpoints, 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 to 24, more preferably 6 to 20, and even more preferably 6 to 18. Examples of the primary aliphatic amine include oleylamine, butylamine, pentylamine, hexylamine, heptylamine, octylamine, 2-ethylhexylamine, nonylamine, aminodecane, aminoundecane, aminododecane (dodecylamine), aminotridecane, tetradecylamine, aminopentadecane, hexadecylamine, aminoheptadecane, stearylamine (octadecylamine), aminononadecane, 2-ethylhexylamine, and the like. Examples of the secondary aliphatic amine include methylhexylamine, methylpentylamine, methyloctylamine, methylnonylamine, methyldecylamine, methylundecylamine, methyldodecylamine, methyloctadecylamine, cyclohexylamine, bis(hexamethylene)triamine, N-butylethylenediamine, and the like. Examples of the tertiary aliphatic amine include dimethylbutylamine, dimethylpentylamine, dimethylhexylamine, methylpentylamine, methyloctylamine, methylnonylamine, methyldecylamine, methylundecylamine, methyldodecylamine, dimethyloctadecylamine, and the like. In one or more embodiments, the aliphatic amine may be one or more compounds represented by the following formula (I).

Chemical formula

[0020] (Aromatic amine) Component A includes aromatic amines in one or more embodiments. The aromatic amine may be one kind or a combination of two or more kinds. 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 viewpoint of etching suppression and improvement of 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 preferable. 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 linear or branched. Examples of the branched alkyl group include an isopropyl group. Examples of the aromatic amine include aniline derivatives (for example, aniline, 2,6-diisopropyl aniline, etc.); triazole derivatives (for example, benzotriazole, 5-methylbenzotriazole, etc.); imidazole derivatives; quinoline derivatives (for example, isoquinoline, etc.); etc., from the viewpoints of etching suppression and storage stability.

[0021] (Amino alcohol) Component A includes amino alcohols in one or more embodiments. The amino alcohol may be one kind or a combination of two or more kinds. 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 a primary, secondary, or tertiary amino group, and a primary amino group is preferable from the viewpoints of etching suppression and improvement of the quality of the layer to be etched. From the viewpoint of storage stability, the number of carbon atoms of the amino alcohol is preferably 2 or more and 24 or less, more preferably 4 or more and 18 or less, and still more preferably 4 or more and 12 or less. Examples of the amino alcohol include 2-(2-aminoethoxy)ethanol, triethanolamine, and the like. In one or more embodiments, the amino alcohol (Component A) may be one or more compounds represented by the following formula (II).

Chemical formula

[0022] As component A, in one or more embodiments, from the viewpoints of etching suppression and improvement in the quality of the layer to be etched, at least one selected from butylamine, octylamine, dodecylamine, octadecylamine, methyloctadecylamine, dimethyloctadecylamine, oleylamine, 2-ethylhexylamine, bis(hexamethylene)triamine, aniline, 2,6-diisopropyl aniline, 5-methylbenzotriazole, and 2-(2-aminoethoxy)ethanol is preferable, and at least one selected from dodecylamine, octadecylamine, methyloctadecylamine, dimethyloctadecylamine, oleylamine, bis(hexamethylene)triamine, aniline, 2,6-diisopropyl aniline, 5-methylbenzotriazole, and 2-(2-aminoethoxy)ethanol is more preferable.

[0023] From the viewpoints of etching suppression and improvement in the quality of the layer to be etched, 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, still more preferably 150 or more, and from the viewpoint of improving the quality of the layer to be etched, it is preferably 350 or less, preferably 300 or less, and more preferably 250 or less. More specifically, the molecular weight of the component A is preferably 70 or more and 350 or less, more preferably 120 or more and 300 or less, and still more preferably 150 or more and 250 or less.

[0024] From the viewpoints of etching suppression and improvement in the quality of the layer to be etched, 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, still more preferably 0.5% by mass or more, and from the viewpoint of storage stability, it is preferably 5% by mass or less, more preferably 3% by mass or less, and still more preferably 2% by mass or less. From the same viewpoints, 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 still more preferably 0.5% by mass or more and 2% by mass or less. When component A is a combination of two or more kinds, the blending amount of component A is the total blending amount thereof.

[0025] [Acid] The acids contained in or formulated in the etching solution of the present disclosure are acids including organic acids, nitric acid, and phosphoric acid. From the perspective of storage stability, in one or more embodiments, the acids contained in or formulated in the etching solution of the present disclosure may include those composed of organic acids, nitric acid, and phosphoric acid (mixed acids). From the perspectives of etching suppression and storage stability, the blending amount of the acid in the etching solution of the present disclosure is preferably 70% by mass or more, more preferably 80% by mass or more, and still more preferably 90% by mass or more.

[0026] (Organic acid) From the perspective 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 perspective, the organic acid is preferably at least one selected from acetic acid, acetic anhydride, methoxyacetic acid, and ethoxyacetic acid, and more preferably acetic acid. The organic acid may be one kind or a combination of two or more kinds. When acetic anhydride is used as the organic acid in preparing the etching solution of the present disclosure, acetic anhydride reacts with the moisture in the etching solution to be converted into acetic acid and water, and it is possible to reduce the amount of moisture in the etching solution. From the perspectives of improving the quality of the layer to be etched and storage stability, 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 blending amount of the organic acid in the etching solution of the present disclosure is preferably 50% by mass or more and 95% by mass or less, and more preferably 70% by mass or more and 90% by mass or less or 80% by mass or more and 90% by mass or less. When the organic acid is a combination of two or more kinds, the blending amount of the organic acid is the total blending amount thereof. Accordingly, in other aspects, the present disclosure relates to an etching solution for etching an etching layer containing at least one metal, which is formulated by blending component A and an acid containing an organic acid, nitric acid, and phosphoric acid, and the blending amount of the organic acid in the etching solution is 80% by mass or more.

[0027] (Nitric acid) From the perspective of improving the quality of the etching layer, the blending 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, still more preferably 1% by mass or more. And from the perspectives of improving the quality of the etching layer and storage stability, it is preferably 10% by mass or less, more preferably 8% by mass or less, still more preferably 5% by mass or less. More specifically, the blending 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, still more preferably 1% by mass or more and 5% by mass or less.

[0028] (Phosphoric acid) From the perspective of improving the quality of the etching layer, the blending 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, still more preferably 1% by mass or more. And from the perspectives of improving the quality of the etching layer and storage stability, it is preferably 40% by mass or less, more preferably 20% by mass or less, still more preferably 10% by mass or less. More specifically, the blending 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, still more preferably 1% by mass or more and 10% by mass or less.

[0029] The mass ratio (organic acid / phosphoric acid) of the compounding amounts of the organic acid and 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 suppression, and, similarly from the viewpoint of etching suppression, 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.

[0030] The mass ratio (organic acid / nitrogen-containing compound) of the compounding amounts of the organic acid and the nitrogen-containing compound (Component A) in the etching solution of the present disclosure is preferably 10 or more, more preferably 20 or more, further preferably 30 or more, even more preferably 40 or more, still more preferably 50 or more, from the viewpoints of etching suppression and reduction of the viscosity of the etching solution, and, from the same viewpoints, is preferably 10,000 or less, more preferably 5,000 or less, further preferably 2,500 or less, even more preferably 1,000 or less, still more preferably 500 or less, 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, further preferably 30 or more and 2,500 or less, even more preferably 40 or more and 1,000 or less, still more preferably 50 or more and 500 or less, even more preferably 50 or more and 100 or less.

[0031] (Other acids) The acid contained or compounded in the etching solution of the present disclosure may further contain an acid other than nitric acid, phosphoric acid, and the organic acid. Examples of the other acid include inorganic acids other than nitric acid and phosphoric acid. Examples of the inorganic acid include hydrochloric acid, sulfuric acid, hydrofluoric acid, and the like.

[0032] [Water] The etching solution of the present disclosure, in one or more embodiments, further contains or is compounded with water. Examples of the water contained or compounded in the etching solution of the present disclosure include distilled water, ion-exchanged water, pure water, and ultrapure water.

[0033] From the perspective of improving the quality of the layer to be etched, 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 still more preferably 5% by mass or less.

[0034] [Other components] The etching solution of the present disclosure may further contain other components as long as the effects of the present disclosure are not impaired. Examples of other components include chelating agents, surfactants, solubilizing agents, preservatives, rust inhibitors, bactericides, antibacterial agents, antioxidants, and the like.

[0035] In one or more embodiments, the etching solution of the present disclosure can be substantially free of polyalkyleneimine and polyalkylene polyamine. Examples of the polyalkyleneimine include polyethyleneimine. Examples of the polyalkylene polyamine include polyalkylene polyamines containing three or more amino groups in one molecule, such as triethylenetetramine. The content of polyalkyleneimine and polyalkylene polyamine 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 still more preferably 0% by mass (i.e., not contained).

[0036] [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 optionally the above-mentioned optional components by 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 method for producing an etching solution of the present disclosure") including at least the step of blending component A, an organic acid, nitric acid, phosphoric acid, and water. In the present disclosure, "formulating at least component A, an organic acid, nitric acid, phosphoric acid, and water" means, in one or more embodiments, mixing component A, the organic acid, nitric acid, phosphoric acid, water, and, if necessary, any of the above-described optional components simultaneously or in sequence. The order of mixing may not be particularly limited. The above formulation can be carried out, for example, using a mixer such as a propeller-type stirrer, liquid circulation stirring by a pump, a homomixer, a homogenizer, an ultrasonic disperser, and a wet ball mill. In the method for producing an etching solution of the present disclosure, the preferred blending amounts of the respective components can be the same as the preferred blending amounts of the respective components in the etching solution of the present disclosure described above.

[0037] In the present disclosure, "the blending amount of each component in the etching solution" means, in one or more embodiments, the blending amount of each component of the etching solution at the time when it is used in the etching process, that is, at the time point (when in use) when starting to be used for the etching treatment. In one or more embodiments, the blending amount of each component in the etching solution of the present disclosure can be regarded as the content of each component in the etching solution of the present disclosure. However, when affected by neutralization, the blending amount and the content may be different.

[0038] Embodiments of the etching solution of the present disclosure may be in the so-called one-component type in which all components are supplied to the market in a pre-mixed state, or in the so-called two-component type in which they are mixed at the time of use. As one embodiment of the two-component type etching solution, it is composed of a solution containing component A (the first liquid) and an acidic aqueous solution containing an organic acid, nitric acid, and phosphoric acid (the second liquid), and the first liquid and the second liquid are mixed at the time of use. After the first liquid and the second liquid are mixed, they may be diluted with water or an acidic aqueous solution if necessary. The first liquid or the second liquid may contain all or part of the total amount of water used for preparing the etching solution. The first liquid and the second liquid may each contain any of the above-described optional components as necessary.

[0039] From the perspective of storage stability, the pH of the etching solution of the present disclosure is preferably 2 or less, more preferably 1 or less. Note that the pH of the etching solution of the present disclosure can preferably be -2.5 or more, more preferably -2 or more. In the present disclosure, the pH of the etching solution is the value at 25°C, which can be measured using a pH meter, specifically, it can be measured by the method described in the examples.

[0040] From the perspective of improving the quality of the layer to be etched, 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, and from the perspective of improving the quality of the layer to be etched, it is preferably 40 mPa·s or less, more preferably 25 mPa·s or less, still 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 B-type viscometer or an Ubbelohde viscometer, specifically, it 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 aqueous acid solution.

[0041] The etching solution of the present disclosure may be stored and supplied in a concentrated state as long as its stability is not impaired. In this case, it is preferable in terms of reducing the manufacturing and transportation costs. And this concentrated solution can be appropriately diluted with water or an aqueous acid solution as needed and used in the etching process. The dilution ratio can be, for example, 5 to 100 times.

[0042] [Kit] In other aspects, the present disclosure relates to a kit for manufacturing 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 aqueous acid solution containing an organic acid, nitric acid, and phosphoric acid (second liquid) in a state where they are not mixed with each other and are mixed at the time of use. After the first liquid and the second liquid are mixed, they may be diluted with water or an aqueous acid solution as necessary. The first liquid or the second liquid may contain all or part of the total amount of water used for preparing the etching solution. The first liquid and the second liquid may each contain any of the above-described optional components as necessary. According to the kit of the present disclosure, an etching solution excellent in storage stability can be prepared.

[0043] [Etching target layer] In one or more embodiments, the etching target layer to be etched using the etching solution of the present disclosure is an etching target layer containing at least one kind of metal. Here, the metal is not particularly limited as long as the effects of the present disclosure are exhibited. For example, 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 for etching an etching target layer containing at least one kind of metal selected from tungsten, molybdenum, niobium, tantalum, and zirconium, and in one or more embodiments, it is preferably used for etching a molybdenum film. That is, in one or more embodiments, the etching target layer includes a molybdenum film. Therefore, in other aspects, the present disclosure relates to an etching solution for etching an etching target layer containing molybdenum, which is prepared by blending component A and an acid containing an organic acid, nitric acid, and phosphoric acid, and the blending amount of the organic acid in the etching solution is 50% by 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 a 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.

[0044] [Etching Method] In one aspect, the present disclosure relates to an etching method (hereinafter, also referred to as "the etching process of the present disclosure") including a step of etching a layer to be etched containing at least one kind of 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. According to the etching method of the present disclosure, in one or more embodiments, by using an etching solution with excellent storage stability, the productivity of the semiconductor substrate can be improved.

[0045] In the etching process of the present disclosure, examples of the etching treatment method include immersion etching, single-wafer etching, and the like.

[0046] From the viewpoint of improving the quality of the layer to be etched, the temperature of the etching solution during etching (etching temperature) in the etching process of the present disclosure is preferably 20°C or higher, more preferably 25°C or higher, still more preferably 30°C or higher. From the viewpoint of improving the quality of the layer to be etched, it is preferably 50°C or lower, more preferably 45°C or lower, still 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, still more preferably 30°C or higher and 40°C or lower.

[0047] In the etching process of the present disclosure, the etching time can be set, for example, to 1 minute or longer and 180 minutes or shorter. From the viewpoint of improving the quality of the layer to be etched, it is preferably 15 minutes or longer and 90 minutes or shorter, more preferably 30 minutes or longer and 60 minutes or shorter.

[0048] In one or more embodiments, the etching solution and the etching method of the present disclosure can be used for etching a metal in the manufacturing process of an electronic device, particularly a semiconductor wafer (semiconductor substrate). Examples of the metal include the metals described above. In one or more embodiments, the etching solution and the etching method of the present disclosure can be suitably used for fabricating 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 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. Thereby, uniform etching of the layer to be etched can be achieved, and productivity and yield can be improved. In one or more embodiments, the etching solution and the etching method of the present disclosure can be used for etching an electrode in the 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, the etching solution and the etching method of the present disclosure can be suitably used for fabricating a pattern having a three-dimensional structure. Thereby, an advanced device such as a memory with increased capacity can be obtained. The etching solution and the etching method of the present disclosure can be used, for example, in an etching method as disclosed in JP-A-2020-145412.

[0049] [Method for manufacturing electronic components] In one aspect, 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") including a step of etching an etching target layer containing at least one metal using an etching solution of the present disclosure (etching step). Examples of the electronic component 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 a 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; a semiconductor memory such as a non-volatile memory including a NAND type flash memory; and the like. As the etching treatment method and etching treatment conditions in the etching step of the method for manufacturing an electronic component of the present disclosure, the same etching treatment method and etching treatment conditions as those in the etching step of the etching method of the present disclosure described above can be mentioned. As the etching target layer, the etching target layer described above can be mentioned.

Example

[0050] Hereinafter, the present disclosure will be specifically described by way of examples, but the present disclosure is not limited to these examples in any way.

[0051] 1. Preparation of etching solution (Examples 1 to 15, Comparative Examples 1 to 9) Nitric acid, phosphoric acid, acetic acid shown in Table 1, a nitrogen-containing compound shown in Table 1, and water were blended to obtain etching solutions (pH: -2.0 to -1.5) of Examples 1 to 15 and Comparative Examples 1 to 9. The blending amounts (mass%, active ingredient) of the respective components shown in Table 1 are used. The blending amount of water is the remainder excluding the acid and the nitrogen-containing compound. Note that the blending amount of water also includes the blending amount of water contained in an acid aqueous solution or the like.

[0052] The following components were used for the preparation of the etching solution. <Acid> Acetic acid [FUJIFILM Wako Pure Chemical Corporation, concentration 100%] Nitric acid [FUJIFILM Wako Pure Chemical Corporation, concentration 70%] Phosphoric acid [manufactured by Rin Chemical Industry Co., Ltd., concentration 85%] <Nitrogen-containing compound> (Aliphatic amine) 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 amine) Aniline [Tokyo Chemical Industry Co., Ltd.] 2,6-Diisopropylaniline [Tokyo Chemical Industry Co., Ltd.] 5-Methylbenzotriazole [Tokyo Chemical Industry Co., Ltd.] (Amino alcohol) 2-(2-Aminoethoxy)ethanol [Tokyo Chemical Industry Co., Ltd.] (Phenols) Catechol [Tokyo Chemical Industry Co., Ltd.] (Polyalkylene polyamine) 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 ultrapure water production device (Pure Conty PC-2000VRL type) and a subsystem (Mac Ace KC-05H type) manufactured by Kurita Water Industries, Ltd.]

[0053] [pH of the etching solution] The pH value of the etching solution at 25°C is the value measured using a pH meter (manufactured by Toa DKK Corporation), and is the numerical value after immersing the electrode of the pH meter in the etching solution for 1 minute.

[0054] [Viscosity of the 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 type viscometer (with thermostat) manufactured by Toki Sangyo Co., Ltd. Rotator: Spindle No. M1, Cord No. 20 Rotation speed: 100 rpm, measure the viscosity value after 60 seconds. Measurement temperature: 25°C Measure the viscosity 30 minutes after the temperature in the thermostat displayed by the device reaches 25°C.

[0055] 2. Evaluation of the etching solution [Solubility (storage stability)] Mix the mixed acid and nitrogen-containing compound shown in Table 1 in the blending amounts (mass%) shown in Table 1 to prepare 20 mL of the etching solution. After stirring them for 10 minutes, visually confirm the solubility. As the evaluation criteria for solubility, when there is no residue after dissolution and the etching solution is colorless and transparent or light yellow and transparent in the temperature range of 0°C to 40°C, it is rated as A; when there is a residue after dissolution but the etching solution is colorless and transparent or light yellow and transparent in the temperature range of 0°C to 40°C, it is rated as B; when the etching solution becomes turbid or shows other states (for example, changes to black) in the temperature range of 0°C to 40°C, it is rated as C, as shown in Table 1. Separately, points that need to be specifically noted are also described in the same column.

[0056] [Evaluation of the etching inhibition rate] Take a specific etching solution as an example. Let the etching rate of the pure mixed acid constituting the etching solution be α, and the etching rate of the etching solution obtained by mixing the mixed acid and the nitrogen-containing compound be β. Then, the etching inhibition rate is calculated by the following formula. The results are shown in Table 1. Etching inhibition rate (%) = 100 × (α - β) / α

[0057] [State of the substrate surface] Molybdenum plates with a length of 2 cm, a width of 2 cm, and a thickness of 0.1 mm, whose weights had been measured in advance, were immersed in the etching solutions (Examples 1 to 15 and Comparative Examples 1 to 5, 9) prepared according to each composition shown in Table 1, and the molybdenum plates were etched at each temperature and each treatment time. However, the etching solutions containing a mixed acid alone and a nitrogen-containing compound were tested under the same etching conditions. After that, after washing with water, the surface of the molybdenum plate was again observed using a KEYENCE shape measurement laser microscope VK-9710 (lens magnification 150 times), and the photograph was analyzed in the surface roughness mode of the same apparatus. Then, the surface accuracy, which is an index of etching unevenness, was determined by the following formula. The evaluation of the etching unevenness of the molybdenum plate was performed based on the following evaluation criteria. The results are shown in Table 1. Surface accuracy (%) = Surface roughness after etching / Surface roughness before etching × 100 <Evaluation criteria> 4: Surface accuracy less than 150% 3: Surface accuracy of 150% or more and less than 200% 2: Surface accuracy of 200% or more and less than 300% 1: Surface accuracy of 300% or more

[0058]

Table 1

[0059] As shown in Table 1, all of the etching solutions of Examples 1 to 15 containing a nitrogen-containing compound with a C / N ratio of 2.2 or more as the nitrogen-containing compound were compared with the etching solution of Comparative Example 6 containing catechol (phenols) instead of the nitrogen-containing compound and the etching solutions of Comparative Examples 7 to 8 containing a nitrogen-containing compound with a C / N ratio of less than 2.2 as the nitrogen-containing compound. It was found that they had good solubility and excellent storage stability. Furthermore, the etching solutions of Examples 1 to 15 containing a nitrogen-containing compound with a C / N ratio of 2.2 or more and having an acetic acid content of 50% by mass or more were compared with Comparative Examples 2 to 4 containing no nitrogen-containing compound and having an acetic acid content of 50% by mass or more, and the etching solution of Comparative Example 5 containing no nitrogen-containing compound and having an acetic acid content of 30% by mass. It was found that they were excellent in etching suppression and the state of the substrate surface was good. Also, the etching solution of Comparative Example 9 in which the blending amount of acetic acid is less than 50% by mass had a worse substrate surface condition than those of Examples 1, 8, and 15 in which the blending amount of acetic acid is 50% by mass or more.

Industrial Applicability

[0060] The etching solution of the present disclosure is excellent in storage stability and can exhibit suppression of etching and improvement in the quality of the surface of the etched layer after etching, and thus is useful in a method for manufacturing a large-capacity semiconductor memory.

Claims

1. An etchant for etching an etched layer containing at least one metal, 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, an acid containing an organic acid, nitric acid, and phosphoric acid, are blended, and the blending amount of the organic acid in the etchant is 50% by mass or more. The etchant.

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

3. The etchant 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 etchant according to claim 1 or 2, 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 etchant according to claim 1 or 2, wherein the blending amount of the nitrogen-containing compound is 0.01% by mass or more and 5% by mass or less.

6. The etchant according to claim 1 or 2, wherein the mass ratio (organic acid / nitrogen-containing compound) of the blending amount of the organic acid to the nitrogen-containing compound is 10 or more and 10,000 or less.

7. Furthermore, the etchant according to claim 1 or 2, which is blended with water.

8. The etchant according to claim 1 or 2, wherein the pH of the etchant is 2 or less.

9. Including a step of etching an etched layer containing at least one metal using the etchant according to claim 1 or 2, The etching method, wherein the temperature of the etchant during etching is 20°C or more and 50°C or less.

10. An etchant for etching an etched layer containing at least one metal, 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, an acid containing an organic acid, nitric acid, and phosphoric acid, is contained, and the blending amount of the organic acid in the etchant is 50% by mass or more. The etchant.

11. An etchant for etching an etched layer containing at least one metal, 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, an acid containing an organic acid, nitric acid, and phosphoric acid, are blended, An etching solution in which the compounding quantity of the organic acid in the etching solution is 80 mass % or more.

12. An etching solution for etching an etched layer containing molybdenum, At least one 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, An acid containing an organic acid, nitric acid, and phosphoric acid, Are blended, An etching solution in which the compounding quantity of the organic acid in the etching solution is 50 mass % or more.

13. A method for manufacturing an electronic component, including a step of etching an etched layer containing at least one metal using the etching solution according to Claim 1 or 2.

Images