Etching liquid composition

Abstract

To provide an etching liquid composition with excellent storage stability.SOLUTION: An etching liquid composition for etching a layer to be etched containing at least one metal includes nitric acid, a polyvalent amine with a number average molecular weight of 300 or more, a nitrogen-containing basic compound having a molecular weight of less than 300, and water.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] In the manufacturing process of a semiconductor device, a process 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 and processed into a predetermined pattern shape. In recent years, the semiconductor field has seen an increase in integration density, which has led to a demand for more complex and finer wiring. This has resulted in increased demands for pattern processing techniques and etching solutions, and various etching methods and etching solutions have been proposed (Patent Documents 1 to 4).

[0003] For example, Patent Document 1 proposes a method for etching a multi-layer film such as a Cu / Mo laminated metal film in one go using an etching solution composition containing 50 to 80 mass% phosphoric acid, 0.5 to 10 mass% nitric acid, 5 to 30 mass% acetic acid, and 0.01 to 5 mass% imidazole. Patent Document 2 proposes a method of etching a titanium-containing layer and a silicon-containing layer using an etching solution containing nitric acid, a fluorine-containing compound, and a nitrogen-containing organic compound A having a plurality of repeating units having a nitrogen atom or a phosphorus-containing compound B. Patent Document 3 proposes an etching solution containing phosphoric acid, nitric acid, and a polyalkylene polyamine containing three or more amino groups in one molecule, which is used for etching a metal film having at least one thin metal layer of molybdenum or a molybdenum alloy. Patent Document 4 proposes an etching solution suitable for both tungsten-containing metals and TiN-containing materials, which contains at least one or more components selected from water, an oxidizing agent, a fluorine-containing etching compound, an organic solvent, a chelating agent, a corrosion inhibitor, and a surfactant. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-49535 A [Patent Document 2] JP2015-144230A [Patent Document 3] JP 2013-237873 A [Patent Document 4] Patent Publication No. 2022-2324 Summary of the Invention [Problem to be solved by the invention]

[0005] As an etching solution, a mixed acid aqueous solution (strong acid aqueous solution) containing phosphoric acid, nitric acid, and acetic acid is generally used. Patent Document 2 proposes adding a nitrogen-containing organic compound such as polyethyleneimine as an agent for suppressing etching and improving etching selectivity, but adding polyethyleneimine or the like to the mixed acid aqueous solution causes turbidity and deteriorates the storage stability of the etching solution. In particular, there is a problem that turbidity is likely to occur when the etching solution is stored at a low temperature (for example, 10°C or lower).

[0006] In view of this, in one aspect, the present disclosure provides an etching solution composition having excellent storage stability and an etching method using the same. [Means for solving the problem]

[0007] In one aspect, the present disclosure relates to an etching solution composition for etching a layer to be etched that contains at least one metal, the etching solution composition comprising nitric acid, a polyamine having a number average molecular weight of 300 or more, a nitrogen-containing basic compound having a molecular weight of less than 300, and water.

[0008] 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 composition of the present disclosure. Effect of the Invention

[0009] According to one aspect of the present disclosure, an etching solution composition having excellent storage stability can be provided. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] As a result of intensive research, the present inventors have found that by using an etching solution containing nitric acid, a polyamine having a number average molecular weight of 300 or more, and a nitrogen-containing basic compound having a molecular weight of less than 300, storage stability can be improved, particularly at low temperatures (10°C or lower).

[0011] In one aspect, the present disclosure relates to an etching solution composition for etching a layer to be etched that contains at least one kind of metal, the etching solution composition comprising nitric acid, a polyamine having a number-average molecular weight of 300 or more, a nitrogen-containing basic compound having a molecular weight of less than 300, and water (hereinafter also referred to as the "etching solution composition of the present disclosure").

[0012] Although the details of the mechanism by which the effects of the present disclosure are manifested are not clear, it is presumed as follows. Polyamines have multiple amino groups in their molecules, and all of these amino groups can form salts with nitric acid in water. Since salts of amino groups and nitric acid are not very soluble in water, the more amino groups that form salts with nitric acid, the lower the solubility in the solution, and the more likely the liquid becomes cloudy, especially at low temperatures (for example, 10°C or lower). In the present disclosure, a polyamine having a number average molecular weight of 300 or more is used in combination with a nitrogen-containing basic compound having a molecular weight of less than 300. As a result, the nitrogen-containing basic compound forms a salt with nitric acid, so the amount of nitrate ions decreases, and the amount of amino groups that form salts with nitric acid in one molecule of polyamine decreases. It is believed that the amount of salts of amino groups and nitric acid in one molecule of polyamine decreases, making the liquid less likely to become cloudy even when stored at low temperatures (for example, 10°C or lower), and improving storage stability. In addition, since the etching solution composition of the present disclosure has a stable composition, it is believed that uniform contact with the layer to be etched can be achieved, allowing uniform etching to be performed. However, the present disclosure need not be construed as being limited to these mechanisms.

[0013] [nitric acid] The amount of nitric acid in the etching solution composition of the present disclosure is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 1.5% by mass or more from the viewpoint of improving the etching rate, and is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 8% by mass or less from the viewpoint of improving storage stability. More specifically, the amount of nitric acid in the etching solution composition of the present disclosure is preferably 0.5% by mass or more and 20% by mass or less, more preferably 1% by mass or more and 10% by mass or less, and even more preferably 1.5% by mass or more and 8% by mass or less.

[0014] [Polyamine with number average molecular weight of 300 or more] The polyvalent amine having a number average molecular weight of 300 or more contained in the etching liquid composition of the present disclosure may be a compound having two or more amino groups in the molecule in one or more embodiments. In one or more embodiments, examples of the polyvalent amine include polymers having structural units derived from polyalkyleneimine, compounds having an amino group and an ethylenically unsaturated double bond, etc., from the viewpoint of etching suppression. Examples of the polyalkyleneimine include polyethyleneimine (PEI), etc., and branched polyethyleneimine is preferable. Examples of the polymer having a structural unit derived from a compound having an amino group and an ethylenically unsaturated double bond include diallylamine copolymer, diallylamine / sulfur dioxide copolymer, diallyldimethylammonium chloride polymer, diallyldimethylammonium chloride / sulfur dioxide copolymer. Among these, from the viewpoint of etching suppression, as the polyvalent amine, polyalkyleneimine such as PEI is preferable. The polyvalent amine having a number average molecular weight of 300 or more may be used alone or in combination of two or more.

[0015] In one or more embodiments, from the viewpoint of etching suppression, the number average molecular weight of the polyvalent amine is 300 or more, preferably 600 or more, more preferably 1,200 or more, and from the viewpoint of improving storage stability, preferably 100,000 or less, more preferably 5,000 or less, still more preferably 3,000 or less. More specifically, the number average molecular weight of the polyvalent amine is preferably 300 or more and 100,000 or less, more preferably 600 or more and 5,000 or less, still more preferably 1,200 or more and 3,000 or less.

[0016] In the present disclosure, the number average molecular weight can be measured by gel permeation chromatography (GPC) under the following conditions. <GPC conditions> Sample solution: Adjusted to a concentration of 0.1 wt% Apparatus / detector: HLC-8320GPC (integrated GPC) manufactured by Tosoh Corporation Column: α-M + α-M (manufactured by Tosoh Corporation) Eluent: 0.15mol / L Na2SO4,1% CH3COOH / water Column temperature: 40℃ Flow rate: 1.0mL / min Sample injection volume: 100μL Standard polymer: Pullulan with known molecular weight (Shodex P-5, P-50, P-200, P-800)

[0017] The amount of the polyamine having a number average molecular weight of 300 or more in the etching solution composition of the present disclosure is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.4% by mass or more from the viewpoint of improving storage stability, and is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less from the viewpoint of the liquid permeability during filtration due to the solution viscosity. More specifically, the amount of the polyamine having a number average molecular weight of 300 or more in the etching solution composition of the present disclosure is preferably 0.1% by mass or more and 20% by mass or less, more preferably 0.2% by mass or more and 10% by mass or less, and even more preferably 0.4% by mass or more and 5% by mass or less. When the polyamine is a combination of two or more kinds, the amount of the polyamine is the total amount thereof.

[0018] [Nitrogen-containing basic compounds having a molecular weight of less than 300] In one or a plurality of embodiments, from the viewpoint of improving storage stability, the molecular weight of the nitrogen-containing basic compound contained in the etching solution composition of the present disclosure is less than 300, preferably 250 or less, and more preferably 200 or less, and from the viewpoint of uniform etching of the layer to be etched, preferably 15 or more, more preferably 20 or more, and even more preferably 30 or more. More specifically, the molecular weight of the nitrogen-containing basic compound is preferably 15 or more and less than 300, more preferably 20 or more and 250 or less, and even more preferably 30 or more and 200 or less.

[0019] In one or a plurality of embodiments, from the viewpoint of improving storage stability, the nitrogen-containing basic compound is preferably at least one selected from ammonia, an alkylamine, an alkanolamine, an alicyclic amine, an aromatic amine, and a polyalkylenepolyamine, and more preferably at least one selected from ammonia, an alicyclic amine, and a polyalkylenepolyamine. The alkylamine may be, for example, ethylamine. The alkanolamine may be, for example, 2-(2-aminoethylamino)ethanol. The alicyclic amine may be, for example, N-(2-hydroxyethyl)piperazine, N-(2-aminoethyl)piperazine. The aromatic amine may be, for example, benzotriazole, aminopyrazole, aminopyridine, aminopyrimidine, aminopyrazine, aminooxazole, or thiazoleamine. From the same viewpoint, the polyalkylenepolyamine is preferably a polyalkylenepolyamine having 2 to 4 amino groups in the molecule, and more preferably at least one selected from alkylenediamines, dialkylenetriamines, and trialkylenetetramines. The alkylenediamine may be, for example, ethylenediamine. The dialkylenetriamine may be, for example, diethylenetriamine. The trialkylenetetramine may be, for example, triethylenetetramine. The nitrogen-containing basic compound having a molecular weight of less than 300 may be used alone or in combination of two or more kinds.

[0020] From the viewpoint of improving storage stability, the blending amount of the nitrogen-containing basic compound having a molecular weight of less than 300 in the etching liquid composition of the present disclosure is preferably 0.4% by mass or more, more preferably 0.8% by mass or more, still more preferably 1.2% by mass or more, and from the viewpoint of the liquid passing property during filtration due to the solution viscosity, it is preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass or less. More specifically, the blending amount of the nitrogen-containing basic compound having a molecular weight of less than 300 in the etching liquid composition of the present disclosure is preferably 0.4% by mass or more and 20% by mass or less, more preferably 0.8% by mass or more and 15% by mass or less, still more preferably 1.2% by mass or more and 10% by mass or less. When the nitrogen-containing basic compound is a combination of two or more kinds, the blending amount of the nitrogen-containing basic compound is the total blending amount thereof.

[0021] In the present disclosure, the blending amount (mass %) a of nitric acid, the blending amount (mass %) b of the polyvalent amine having a number average molecular weight of 300 or more, and the blending amount (mass %) c of the nitrogen-containing basic compound having a molecular weight of less than 300 satisfy (a - c) 4 / b ≦ 600. It is preferable that a and c satisfy the relationship of a < c, a = c, or a > c in one or more embodiments. Note that a, b, and c each represent mass or mass % (hereinafter the same). (a - c) 4 / b is preferably 600 or less, more preferably 550 or less, still more preferably 500 or less, still more preferably 400 or less from the viewpoint of improving storage stability and improving storage stability at a temperature of 10°C or lower, and from the viewpoint of uniform etching of the layer to be etched, it is preferably 0.01 or more, more preferably 0.1 or more, still more preferably 0.5 or more, 50 or more, 100 or more, 200 or more, or 300 or more. From the same viewpoint, (a - c) 4 / b is preferably 0.01 or more and 600 or less, more preferably 0.1 or more and 600 or less, still more preferably 0.5 or more and 600 or less, still more preferably 50 or more and 600 or less, still more preferably 100 or more and 600 or less, still more preferably 200 or more and 600 or less, still more preferably 300 or more and 600 or less, still more preferably 300 or more and 550 or less, still more preferably 300 or more and 500 or less.

[0022] Here, (ac) 4 The reason why / b is preferably 600 or less will be explained below. As described above, polyamines have a plurality of amino groups in the molecule, and all of these amino groups can form salts with nitric acid in water. How many amino groups in the molecule of polyamine form salts with nitric acid depends on the amount of nitrate ions and ammonium ions contained in the etching solution composition. When the amount of polyamine is increased, the amount of nitrate ions decreases relatively to the amount of ammonium ions, so the amount of amino groups that form salts with nitric acid in one molecule of polyamine decreases. When the amount of nitric acid is increased, the amount of nitrate ions in the etching solution composition increases dramatically because the pH is greatly reduced in addition to the increase in the amount of nitric acid, and the amount of amino groups that form salts with nitric acid in one molecule of polyamine increases greatly. When a polyamine having a number average molecular weight of 300 or more and a nitrogen-containing basic compound having a molecular weight of less than 300 coexist, the nitrogen-containing basic compound forms a salt with nitric acid, so the amount of nitrate ions decreases, and it is considered that the amount of amino groups that form salts with nitric acid in one molecule of polyamine decreases. In addition, since amines / nitrates are not very soluble in water, when the concentration of water is low, the greater the number of amino groups that form salts with nitric acid, the lower the solubility in the solution, and the more likely the liquid will become cloudy, especially at low temperatures (e.g., below 10°C). As mentioned above, the amount of salt formed depends on the amount of nitrate ions and ammonium ions, which is greatly affected by the amount of nitric acid and the amount of nitrogen-containing basic compounds. The present inventors have confirmed in detail the effect of the ratio of the amount of nitrate ion to the amount of ammonium ion, and as a result, it has been found that the amount of nitric acid (% by mass) a, the amount of polyamine having a number average molecular weight of 300 or more (% by mass) b, and the amount of nitrogen-containing basic compound having a molecular weight of less than 300 (% by mass) c are (ac) 4 It was revealed that when the relationship of / b≦600 is satisfied, the liquid is less likely to become cloudy even when stored at a low temperature (for example, 10° C. or lower), and storage stability can be further improved. Furthermore, since the etching solution has a more stable composition, it is believed that the etching solution can contact the layer to be etched more uniformly, and etching can be performed with less unevenness.

[0023] [Acids other than nitric acid] The etching solution composition of the present disclosure may further contain an acid other than nitric acid from the viewpoint of uniform etching of the layer to be etched. The acid other than nitric acid may be used alone or in combination of two or more kinds. Examples of acids other than nitric acid include at least one selected from phosphoric acid, hydrochloric acid, sulfuric acid, and organic acids. Examples of organic acids include at least one selected from formic acid, acetic acid, methoxyacetic acid, ethoxyacetic acid, propionic acid, butyric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, fumaric acid, phthalic acid, trimellitic acid, hydroxyacetic acid, lactic acid, salicylic acid, malic acid, tartaric acid, citric acid, aspartic acid, and glutamic acid. Among these, the acid other than nitric acid is preferably at least one selected from phosphoric acid, acetic acid, methoxyacetic acid, and ethoxyacetic acid, more preferably at least one of phosphoric acid and acetic acid, and more preferably a combination of phosphoric acid and acetic acid, from the viewpoint of uniform etching of the layer to be etched.

[0024] When the etching solution of the present disclosure further contains an acid other than nitric acid, the amount of the acid other than nitric acid in the etching solution of the present disclosure is preferably 65% ​​by mass or more, more preferably 70% by mass or more, and even more preferably 75% by mass or more from the viewpoint of uniform etching of the layer to be etched, and from the same viewpoint, it is preferably 98% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less. More specifically, the amount of the acid other than nitric acid in the etching solution composition of the present disclosure is preferably 65% ​​by mass or more and 98% by mass or less, more preferably 70% by mass or more and 95% by mass or less, and even more preferably 75% by mass or more and 90% by mass or less. When the type of acid other than nitric acid is a combination of two or more kinds, the amount of the acid other than nitric acid is the total amount of them. When the acid other than nitric acid is a combination of phosphoric acid and acetic acid, the amount of phosphoric acid in the etching solution composition of the present disclosure is preferably 50% by mass or more and 95% by mass or less, more preferably 55% by mass or more and 93% by mass or less, and even more preferably 60% by mass or more and 90% by mass or less, from the viewpoint of uniform etching of the layer to be etched. From the same viewpoint, the amount of acetic acid in the etching solution composition of the present disclosure is preferably 2% by mass or more and 80% by mass or less, more preferably 3% by mass or more and 60% by mass or less, and even more preferably 5% by mass or more and 30% by mass or less.

[0025] [water] In one or more embodiments, the etching solution composition of the present disclosure contains water. Examples of the water contained in the etching solution composition of the present disclosure include distilled water, ion-exchanged water, pure water, and ultrapure water.

[0026] The amount of water in the etching solution composition of the present disclosure is preferably 2% by mass or more, more preferably 5% by mass or more, and even more preferably 7% by mass or more from the viewpoint of improving storage stability, and is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less from the viewpoint of uniform etching of the layer to be etched. More specifically, the amount of water in the etching solution composition of the present disclosure is preferably 2% by mass or more and 30% by mass or less, more preferably 5% by mass or more and 25% by mass or less, and even more preferably 7% by mass or more and 20% by mass or less.

[0027] [Other ingredients] The etching solution composition of the present disclosure may further contain other components within the scope of the present disclosure, such as a chelating agent, a surfactant, a solubilizing agent, a preservative, a rust inhibitor, a bactericide, an antibacterial agent, and an antioxidant.

[0028] In one or more embodiments, the etching solution composition of the present disclosure may be substantially free of imidazole. The amount of imidazole in the etching solution composition 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 imidazole is included).

[0029] In one or more embodiments, the etching solution composition of the present disclosure may be substantially free of a fluorine-containing compound. The amount of the fluorine-containing compound in the etching solution composition of the present disclosure is preferably less than 0.001% by mass, more preferably 0.0001% by mass or less, and even more preferably 0% by mass (i.e., no fluorine-containing compound is contained).

[0030] In one or more embodiments, the etching solution composition of the present disclosure may or may not contain hydrogen peroxide.

[0031] In one or a plurality of embodiments, the etching solution composition of the present disclosure does not develop turbidity at temperatures of preferably 10° C. or higher, more preferably 5° C. or higher, even more preferably 1° C. or higher, even more preferably 0.5° C. or higher, and even more preferably 0° C. or higher. The presence or absence of turbidity can be confirmed by the method described in the examples.

[0032] [Method of manufacturing the etching solution composition] In one embodiment, the etching solution composition of the present disclosure is obtained by blending nitric acid, a polyamine having a number average molecular weight of 300 or more, a nitrogen-containing basic compound having a molecular weight of less than 300, water, and, if desired, the above-mentioned optional components, by a known method. Thus, in one embodiment, the present disclosure relates to a method for producing an etching solution composition (hereinafter also referred to as the "etching solution production method of the present disclosure") that includes a step of blending at least nitric acid, a polyamine having a number average molecular weight of 300 or more, a nitrogen-containing basic compound having a molecular weight of less than 300, and water. In the present disclosure, "blending at least nitric acid, a polyamine having a number average molecular weight of 300 or more, a nitrogen-containing basic compound having a molecular weight of less than 300, and water" includes, in one or more embodiments, simultaneously or sequentially mixing nitric acid, a polyamine having a number average molecular weight of 300 or more, a nitrogen-containing basic compound having a molecular weight of less than 300, water, and, if necessary, the above-mentioned optional components. The order of mixing is not particularly limited. The blending can be performed using a mixer such as a propeller-type agitator, a pump for liquid circulation agitation, a homomixer, a homogenizer, an ultrasonic disperser, and a wet ball mill. In the method for producing an etching solution according to the present disclosure, the preferred amount of each component may be the same as the preferred amount of each component in the etching solution composition according to the present disclosure described above.

[0033] In the present disclosure, the "amount of each component in the etching solution composition" refers, in one or more embodiments, to the amount of each component of the etching solution composition used in the etching step, i.e., at the time of starting use in the etching treatment (at the time of use). In one or more embodiments, the blending amount of each component in the etching solution composition of the present disclosure can be regarded as the content of each component in the etching solution composition of the present disclosure. However, when the component is affected by neutralization, the blending amount and the content may differ.

[0034] The embodiment of the etching solution composition of the present disclosure may be a so-called one-liquid type in which all components are supplied to the market in a premixed state, or a so-called two-liquid type in which the components are mixed at the time of use. One embodiment of the two-liquid type etching solution composition is composed of a solution (first liquid) containing nitric acid and a solution (second liquid) containing a polyamine having a number average molecular weight of 300 or more and a nitrogen-containing basic compound having a molecular weight of less than 300, 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 acid aqueous solution as necessary. The first liquid or the second liquid may contain all or a part of the water used to prepare the etching solution. The first liquid and the second liquid may each contain the above-mentioned optional components as necessary.

[0035] The pH of the etching solution composition of the present disclosure is preferably 1 or less, more preferably 0 or less, even more preferably less than 0, and even more preferably about -1, from the viewpoint of uniform etching of the layer to be etched. The pH of the etching solution composition of the present disclosure can be preferably -5 or more, more preferably -3 or more. In the present disclosure, the pH of the etching solution composition is a value at 25°C, and can be measured using a pH meter, specifically, by the method described in the Examples.

[0036] The etching solution composition of the present disclosure may be stored and supplied in a concentrated state to the extent that its stability is not impaired. In this case, it is preferable in that the manufacturing and transportation costs can be reduced. The concentrated solution can be appropriately diluted with water or an aqueous acid solution as necessary and used in the etching process. The dilution ratio can be, for example, 5 to 100 times.

[0037] [kit] In another aspect, the present disclosure relates to a kit for producing the etching liquid composition of the present disclosure (hereinafter also referred to as the "kit of the present disclosure"). The kit of the present disclosure includes, for example, a kit (two-liquid etching solution) that contains a solution (first liquid) containing nitric acid and a solution (second liquid) containing a polyamine having a number average molecular weight of 300 or more and a nitrogen-containing basic compound having a molecular weight of less than 300 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 necessary. The first liquid or the second liquid may contain all or a part of the water used to prepare the etching solution. The first liquid and the second liquid may each contain the above-mentioned optional components as necessary. According to the kit of the present disclosure, an etching solution having excellent storage stability can be prepared.

[0038] [Layer to be etched] In one or more embodiments, the layer to be etched using the etching solution composition of the present disclosure is a layer to be etched that contains 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 composition of the present disclosure is preferably used for etching a layer to be etched that contains at least one metal selected from the group consisting of tungsten, molybdenum, niobium, tantalum, and zirconium, and in one or more embodiments, it is preferably used for etching a tungsten film or a molybdenum film. That is, in one or more embodiments, the layer to be etched includes a tungsten film or a molybdenum film.

[0039] [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") including a step of etching a layer to be etched that contains at least one metal using the etching solution composition of the present disclosure (hereinafter also referred to as the "etching step of the present disclosure"). By using 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 having excellent storage stability.

[0040] In the etching step of the present disclosure, examples of the etching method include immersion etching and single wafer etching.

[0041] In one or more embodiments, when the layer to be etched is a tungsten film, the temperature of the etching solution composition in the etching step of the present disclosure (etching temperature) is, from the viewpoint of reducing etching unevenness, preferably 0° C. or higher, more preferably 50° C. or higher, even more preferably 70° C. or higher, and preferably 150° C. or lower, more preferably 130° C. or lower, and even more preferably 110° C. or lower. More specifically, in one or more embodiments, when the layer to be etched is a tungsten film, the etching temperature is preferably 0° C. or higher and 150° C. or lower, more preferably 50° C. or higher and 130° C. or lower, and even more preferably 70° C. or higher and 110° C. or lower. In one or more embodiments, when the layer to be etched is a molybdenum film, the temperature of the etching solution composition in the etching step of the present disclosure (etching temperature) is, from the viewpoint of reducing etching unevenness, preferably 0° C. or higher, more preferably 15° C. or higher, even more preferably 20° C. or higher, and preferably 80° C. or lower, more preferably 65° C. or lower, and even more preferably 50° C. or lower. More specifically, in one or more embodiments, when the layer to be etched is a molybdenum film, the etching temperature is preferably 0° C. or higher and 80° C. or lower, more preferably 15° C. or higher and 65° C. or lower, and even more preferably 20° C. or higher and 50° C. or lower. In one or more embodiments, when the layer to be etched is a nickel film, the temperature of the etching solution composition in the etching step of the present disclosure (etching temperature) is, from the viewpoint of reducing etching unevenness, preferably 0° C. or higher, more preferably 15° C. or higher, even more preferably 30° C. or higher, and preferably 80° C. or lower, more preferably 65° C. or lower, and even more preferably 50° C. or lower. More specifically, in one or more embodiments, when the layer to be etched is a nickel film, the etching temperature is preferably 0° C. or higher and 80° C. or lower, more preferably 15° C. or higher and 65° C. or lower, and even more preferably 30° C. or higher and 50° C. or lower. In one or more embodiments, when the layer to be etched is a cobalt film, the temperature of the etching solution composition in the etching step of the present disclosure (etching temperature) is, from the viewpoint of reducing etching unevenness, preferably 0° C. or higher, more preferably 15° C. or higher, even more preferably 30° C. or higher, and preferably 80° C. or lower, more preferably 65° C. or lower, and even more preferably 50° C. or lower. More specifically, in one or more embodiments, when the layer to be etched is a cobalt film, the etching temperature is preferably 0° C. or higher and 80° C. or lower, more preferably 15° C. or higher and 65° C. or lower, and even more preferably 30° C. or higher and 50° C. or lower. In one or more embodiments, when the layer to be etched is a titanium film, the temperature of the etching solution composition in the etching step of the present disclosure (etching temperature) is, from the viewpoint of reducing etching unevenness, preferably 0° C. or higher, more preferably 50° C. or higher, even more preferably 70° C. or higher, and preferably 150° C. or lower, more preferably 130° C. or lower, and even more preferably 110° C. or lower. More specifically, in one or more embodiments, when the layer to be etched is a titanium film, the etching temperature is preferably 0° C. or higher and 150° C. or lower, more preferably 50° C. or higher and 130° C. or lower, and even more preferably 70° C. or higher and 110° C. or lower. In one or more embodiments, when the layer to be etched is a copper film, the temperature of the etching solution composition in the etching step of the present disclosure (etching temperature) is, from the viewpoint of reducing etching unevenness, preferably 0° C. or higher, more preferably 15° C. or higher, even more preferably 30° C. or higher, and preferably 80° C. or lower, more preferably 65° C. or lower, and even more preferably 50° C. or lower. More specifically, in one or more embodiments, when the layer to be etched is a copper film, the etching temperature is preferably 0° C. or higher and 80° C. or lower, more preferably 15° C. or higher and 65° C. or lower, and even more preferably 30° C. or higher and 50° C. or lower.

[0042] In the etching process of the present disclosure, the etching time can be set to, for example, 1 minute or more and 180 minutes or less.

[0043] In one or a plurality of embodiments, the etching method of the present disclosure may include a step of storing, storing, or transporting the etching solution composition of the present disclosure at a temperature of 10° C. or lower.

[0044] In one or a plurality of embodiments, the etching solution composition and the etching method of the present disclosure can be used to etch metals in the manufacturing process of electronic devices, particularly semiconductor wafers. In one or more embodiments, the etching solution composition and the etching method of the present disclosure can be suitably used in the production of semiconductor wafers, thereby improving etching unevenness and improving productivity and yield. In one or a plurality of embodiments, the etching solution composition and the 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 composition and the etching method of the present disclosure can be suitably used for producing a pattern having a three-dimensional structure, thereby making it possible to obtain an advanced device such as a large-capacity memory. The etching solution composition and the etching method of the present disclosure can be used, for example, in an etching method such as that disclosed in JP2020-145412A. EXAMPLES

[0045] The present disclosure will be specifically described below with reference to examples, but the present disclosure is not limited to these examples in any way.

[0046] 1. Preparation of Etching Solution (Examples 1 to 6, Comparative Example 1) Nitric acid, acids other than nitric acid (phosphoric acid, acetic acid), polyamines, nitrogen-containing basic compounds, and water shown in Table 1 were mixed to obtain etching solutions (pH: -1) of Examples 1 to 6 and Comparative Example 1. The amount of each component (mass %, effective amount) in the prepared etching solution is shown in Table 1. The amount of water in Table 1 includes the amount of water contained in the acid aqueous solution, etc.

[0047] The following components were used to prepare the etching solution. Nitric acid [FUJIFILM Wako Pure Chemical Corporation, concentration 70%] Phosphoric acid [Rinkagaku Kogyo Co., Ltd., concentration 85%] Acetic acid [FUJIFILM Wako Pure Chemical Corporation, concentration 100%] PEI (polyethyleneimine) [number average molecular weight 1,800, "Epomin SP-018" manufactured by Nippon Shokubai Co., Ltd.] Ethylenediamine [molecular weight 60.1, Fujifilm Wako Pure Chemical Corporation] NH3 (ammonia) [molecular weight 17.03, Kishida Chemical Co., Ltd., concentration 28%] Triethylenetetramine [molecular weight 146.23, Fujifilm Wako Pure Chemical Industries, Ltd.] Water [Ultrapure water produced using a continuous pure water production system (Pure Conti PC-2000VRL type) and subsystem (Macace KC-05H type) manufactured by Kurita Water Industries Ltd.]

[0048] 2.Measuring methods for each parameter [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.

[0049] 3.Evaluation of etching solutions [Whether or not turbidity occurs (storage stability)] Immediately after preparation, 20 ml of the etching solution composition was placed in a sample bottle, and the presence or absence of turbidity was visually confirmed when left to stand at 1° C. Samples that did not develop turbidity even after being left to stand for 48 hours or more were rated A, samples that developed turbidity between 24 and 48 hours were rated B, and samples that developed turbidity within 24 hours or less were rated C. The results are shown in Table 1.

[0050] [Evaluation of uneven etching of molybdenum plate] The etching solutions prepared to each composition (Examples 1 to 6 and Comparative Example 1) were stored at 1° C. for one week, and then a molybdenum plate with a length of 2 cm, width of 2 cm, and thickness of 0.1 mm, the weight of which had been measured in advance, was immersed in the etching solution, and the molybdenum plate was etched at 40° C. for 30 minutes. After that, the surface of the molybdenum plate was again observed using a shape measuring laser microscope VK-9710 (lens magnification 150 times) manufactured by KEYENCE Corporation, and a photograph was analyzed using the surface roughness mode of the same device after washing with water. Then, the surface roughness, which is an index of etching unevenness, was calculated by the following formula. The results are shown in Table 1. It can be determined that the smaller the surface roughness value, the more the etching unevenness is suppressed. Surface precision (%) = Surface roughness after etching / Surface roughness before etching x 100

[0051] [Table 1]

[0052] As shown in Table 1, all of the etching solution compositions of Examples 1 to 6 were found to have excellent storage stability, suppressing the generation of turbidity even when stored at low temperatures, compared to Comparative Example 1, which did not contain a nitrogen-containing basic compound having a molecular weight of less than 300. In addition, in Examples 1 to 6, (ac) 4It was found that the relationship between SiO2 and SiO2 / b was 0.01 or more and 600 or less, which effectively suppressed etching unevenness. [Industrial Applicability]

[0053] The etching solution composition of the present disclosure has excellent storage stability and is useful in a method for producing a large-capacity semiconductor memory.

Claims

1. An etching solution composition for etching a layer to be etched, comprising at least one metal, The etching solution composition comprises nitric acid, a polyhydric amine having a number average molecular weight of 300 or more, a nitrogen-containing basic compound having a molecular weight of less than 300, and water.

2. The amount of nitric acid (mass%) a, the amount of polyhydric amine with a number average molecular weight of 300 or more (mass%) b, and the amount of nitrogen-containing basic compound with a molecular weight of less than 300 (mass%) c are (a - c) 4 The etching solution composition according to claim 1, satisfying the relationship / b ≤ 600.

3. The etching solution composition according to claim 1 or 2, further comprising an acid other than nitric acid.

4. The etching solution composition according to claim 3, wherein the acid other than nitric acid is at least one selected from phosphoric acid, acetic acid, methoxyacetic acid, and ethoxyacetic acid.

5. The etching solution composition according to claim 1 or 2, wherein the metal is 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.

6. An etching method comprising the step of etching a layer to be etched, which contains at least one metal, using the etching solution composition according to claim 1 or 2.