Etching solution composition

Abstract

To provide an etchant composition with excellent storage stability.SOLUTION: The etchant composition is for etching a layer to be etched containing at least one metal. The etchant composition includes nitric acid, a polyvalent amine having a number average molecular weight of 300 or more, and water. The blending amount of water is equal to or less than 30 mass%. The blending amount of nitric acid (mass%) a and the blending amount of polyvalent amine (mass%) b having an average molecular weight of 300 or more satisfy the relationship a4 / b≤600.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to an etching solution composition 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 into a predetermined pattern shape is performed. In recent years, in the semiconductor field, high integration has been progressing, and the complexity and miniaturization of wiring are required. 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 4).

[0003] For example, in Patent Document 1, a method of collectively etching a multilayer film such as a Cu / Mo laminated metal film using an etching solution composition containing 50 to 80% by mass of phosphoric acid, 0.5 to 10% by mass of nitric acid, 5 to 30% by mass of acetic acid, and 0.01 to 5% by mass of imidazole has been proposed. In Patent Document 2, 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 has been proposed. In Patent Document 3, 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. Patent Document 4 proposes an etching solution suitable for both tungsten-containing metals and TiN-containing materials, comprising 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] Japanese Patent Publication No. 2012-49535 [Patent Document 2] Japanese Patent Publication No. 2015-144230 [Patent Document 3] Japanese Patent Publication No. 2013-237873 [Patent Document 4] Japanese Patent Publication No. 2022-42324 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] A mixed acid aqueous solution (strongly acidic aqueous solution) containing phosphoric acid, nitric acid, and acetic acid is commonly used as an etching solution. Patent Document 2 proposes adding nitrogen-containing organic compounds such as polyethyleneimine as an agent to suppress etching and improve etching selectivity. However, 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 stored at low temperatures (for example, below 10°C).

[0006] Therefore, in one embodiment, this disclosure provides an etching solution composition with excellent storage stability and an etching method using the same. [Means for solving the problem]

[0007] This disclosure relates, in one aspect, to an etching solution composition for etching a layer to be etched containing at least one metal, wherein the etching solution composition comprises nitric acid, a polyhydric amine having a number average molecular weight of 300 or more, and water, wherein the amount of water is 30% by mass or less, and the amount of nitric acid (mass%) a and the amount of polyhydric amine having a number average molecular weight of 300 or more (mass%) b are a 4 This invention relates to etching solution compositions that satisfy the relationship / b ≤ 600. Note that a and b represent mass or mass % (the same applies hereafter).

[0008] This disclosure relates, in one embodiment, to an etching method comprising the step of etching a layer to be etched, which contains at least one metal, using the etching solution composition of this disclosure. [Effects of the Invention]

[0009] According to this disclosure, in one embodiment, an etching solution composition with excellent storage stability can be provided. [Modes for carrying out the invention]

[0010] As a result of diligent research by the inventors, it was found that by using an etching solution containing nitric acid and a polyhydric amine with a number average molecular weight of 300 or more in a predetermined ratio, storage stability can be improved, particularly storage stability at low temperatures (below 10°C).

[0011] This disclosure relates, in one aspect, to an etching solution composition for etching a layer to be etched containing at least one metal, wherein the etching solution composition comprises nitric acid, a polyhydric amine having a number average molecular weight of 300 or more, and water, wherein the amount of water is 30% by mass or less, and the amount of nitric acid (mass%) a and the amount of polyhydric amine having a number average molecular weight of 300 or more (mass%) b are a 4 This invention relates to an etching solution composition (hereinafter also referred to as "the etching solution composition of this disclosure") that satisfies the relationship / b ≤ 600.

[0012] Although the detailed mechanism of how the effects of this disclosure are realized is not clear, it is presumed to be as follows. Polyhydric amines have multiple amino groups in their molecules, and all of these amino groups can form salts with nitric acid in water. The number of amino groups in a polyhydric amine molecule that form salts with nitric acid depends on the amount of nitrate ions and ammonium ions contained in the etching solution composition. As the amount of polyhydric amine increases, 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 polyhydric amine molecule decreases. As the amount of nitric acid increases, in addition to the increase in the amount of nitric acid, the pH decreases significantly, so the amount of nitrate ions in the etching solution composition increases dramatically, and the amount of amino groups that form salts with nitric acid in one polyhydric amine molecule increases significantly. Also, since amine / nitrate salts are not very soluble in water, at low water concentrations, the more amino groups that form salts with nitric acid, the lower the solubility in the solution, and turbidity of the solution is likely to occur, 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, and this is greatly affected by the amount of nitric acid. The inventors have confirmed in detail the effect of the ratio of nitrate ions to ammonium ions, and found that the amount of nitrate (mass%) a and the amount of polyhydric amine with a number average molecular weight of 300 or more (mass%) b are a 4 We have demonstrated that when the relationship / b ≤ 600 is satisfied, turbidity of the liquid is less likely to occur even when stored at low temperatures (e.g., below 10°C), thus improving storage stability. Furthermore, since the etching solution composition of this disclosure has a stable composition, it is believed that uniform contact with the layer to be etched can be achieved, resulting in uniform etching. However, this disclosure does not have to be construed as being limited to these mechanisms.

[0013] [nitric acid] From the viewpoint of improving the etching rate, the amount of nitric acid in the etching solution composition of this 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 storage stability, it is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less. More specifically, the amount of nitric acid in the etching solution composition of this 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 5% by mass or less.

[0014] [Polyhydramines] The polyhydric amine contained in the etching solution composition of this disclosure may, in one or more embodiments, be any compound having two or more amino groups in its molecule. Examples of polyhydric amines, from the viewpoint of etching suppression, in one or more embodiments include polyalkyleneimines, polyalkylene polyamines, alkanolamines, alicyclic amines, polymers having structural units derived from compounds having an amino group and an ethylenically unsaturated double bond, aromatic amines, and the like. Examples of polyalkyleneimines include polyethyleneimine (PEI), with branched polyethyleneimine being preferred. Examples of polyalkylene polyamines include diethylenetriamine and pentaethylenehexamine. Examples of alkanolamines include 2-(2-aminoethylamino)ethanol. Examples of alicyclic amines include N-(2-hydroxyethyl)piperazine and N-(2-aminoethyl)piperazine. Polymers having constituent units derived from compounds with an amino group and an ethylenically unsaturated double bond include, for example, diallylamine copolymers, diallylamine / sulfur dioxide copolymers, diallyldimethylammonium chloride polymers, and diallyldimethylammonium chloride / sulfur dioxide copolymers. Aromatic amines include, for example, benzotriazole, aminopyrazole, aminopyridine, aminopyrimidine, aminopyrazine, aminooxazole, and thiazoleamine. Among these, polyalkyleneimines such as PEI are preferred from the viewpoint of etching suppression. The polyvalent amine may be used alone or in combination of two or more kinds.

[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, it is 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: 0.15 mol / L Na2SO4, 1% CH3COOH / water Column temperature: 40 °C Flow rate: 1.0 mL / min Sample solution injection volume: 100 μL Standard polymer: Pullulan with known molecular weight (Shodex P-5, P-50, P-200, P-800)

[0017] The amount of polyhydric amine in the etching solution composition of this 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 from the viewpoint of liquid permeability during filtration due to solution viscosity, it is preferably 20% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less. More specifically, the amount of polyhydric amine in the etching solution composition of this 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 there is a combination of two or more polyhydric amines, the amount of polyhydric amines is the total amount of those combined.

[0018] In this disclosure, when the amount of nitric acid (mass%) is a and the amount of polyhydric amine having a number average molecular weight of 300 or more (mass%) is b, the amount of nitric acid a and the amount of polyhydric amine having a number average molecular weight of 300 or more b are a 4 The relationship / b ≤ 600 is satisfied. 4 From the viewpoint of improving storage stability and storage stability at temperatures below 10°C, / b is preferably 600 or less, more preferably 550 or less, more preferably 500 or less, and even more preferably 450 or less. From the viewpoint of uniform etching of the etched layer, it is preferably 0.01 or more, more preferably 0.1 or more, and even more preferably 0.5 or more.

[0019] [Acids other than nitric acid] The etching solution composition of this 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 individually or in combination of two or more types. 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, from the viewpoint of uniform etching of the etched layer, at least one selected from phosphoric acid, acetic acid, methoxyacetic acid, and ethoxyacetic acid is preferred as an acid other than nitric acid, at least one of phosphoric acid and acetic acid is more preferred, and a combination of phosphoric acid and acetic acid is even more preferred.

[0020] If the etching solution of this disclosure further contains an acid other than nitric acid, the amount of the acid other than nitric acid in the etching solution of this disclosure is preferably 65% ​​by mass or more, more preferably 70% by mass or more, and even more preferably 75% by mass or more, and from the viewpoint of uniform etching of the layer to be etched, 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 this 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. If the types of acids other than nitric acid are a combination of two or more, the amount of the acids other than nitric acid is the total amount of those acids. 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 this disclosure is preferably 50% to 95% by mass, more preferably 55% to 93% by mass, and even more preferably 60% to 90% by mass, from the viewpoint of uniform etching of the layer to be etched. From a similar viewpoint, the amount of acetic acid in the etching solution composition of this disclosure is preferably 2% to 80% by mass, more preferably 3% to 60% by mass, and even more preferably 5% to 30% by mass.

[0021] [water] The etching solution compositions of this disclosure include water in one or more embodiments. Examples of water contained in the etching solution of this disclosure include distilled water, deionized water, pure water, and ultrapure water.

[0022] The amount of water in the etching solution composition of this 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 from the viewpoint of uniform etching of the layer to be etched, it is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less. More specifically, the amount of water in the etching solution composition of this 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.

[0023] [Other ingredients] The etching solution composition of this disclosure may further contain other components, to the extent that the effects of this disclosure are not impaired. Examples of other components include chelating agents, surfactants, solubilizers, preservatives, rust inhibitors, bactericides, antimicrobial agents, and antioxidants.

[0024] In one or more embodiments, the etching solution compositions of this disclosure may be substantially free of imidazole. The amount of imidazole in the etching solution compositions of this disclosure is preferably less than 0.01% by mass, more preferably 0.001% by mass or less, and even more preferably 0% by mass.

[0025] In one or more embodiments, the etching solution compositions of this disclosure may be substantially free of fluorine-containing compounds. The amount of fluorine-containing compounds in the etching solution compositions of this disclosure is preferably less than 0.001% by mass, more preferably 0.0001% by mass or less, and even more preferably 0% by mass.

[0026] In one or more embodiments, the etching solution composition of this disclosure may contain hydrogen peroxide or may not contain hydrogen peroxide.

[0027] The etching solution compositions of this disclosure do not become turbid 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, in one or more embodiments. The presence or absence of turbidity can be confirmed by the method described in the examples.

[0028] [Method for producing etching solution composition] In one embodiment, the etching solution composition of this disclosure is obtained by blending nitric acid, a polyhydric amine having a number average molecular weight of 300 or more, water, and optionally the above-mentioned optional components in a known manner. Accordingly, in one embodiment, this disclosure relates to a method for producing an etching solution composition (hereinafter also referred to as "the etching solution production method of this disclosure") which includes at least the step of blending nitric acid, a polyhydric amine having a number average molecular weight of 300 or more, and water. In this disclosure, "combining at least nitric acid, a polyhydric amine having a number average molecular weight of 300 or more, and water" means, in one or more embodiments, simultaneously or sequentially mixing nitric acid, a polyhydric amine having a number average molecular weight of 300 or more, water, and any of the above-mentioned optional components as needed. The order of mixing is not particularly limited. The compounding can be carried out using, for example, a mixer such as a propeller-type stirrer, liquid circulation stirring with a pump, a homomixer, a homogenizer, an ultrasonic disperser, and a wet ball mill. In the etching solution manufacturing method of this disclosure, the preferred blending amounts of each component can be the same as the preferred blending amounts of each component in the etching solution composition of this disclosure described above.

[0029] In this disclosure, "amount of each component in the etching solution composition" means, in one or more embodiments, the amount of each component of the etching solution composition used in the etching process, i.e., at the time of use when the etching process begins (at the time of use). The amounts of each component in the etching solution composition of this disclosure can be considered as the content of each component in the etching solution composition of this disclosure in one or more embodiments. However, the amounts of each component and the content may differ when neutralization is involved.

[0030] Embodiments of the etching solution composition of this disclosure may be a so-called one-component type, in which all components are supplied to the market in a pre-mixed state, or a so-called two-component type, in which the components are mixed at the time of use. One embodiment of a two-component etching solution composition is composed of a solution containing nitric acid (first solution) and a solution containing a polyhydric amine having a number average molecular weight of 300 or more (second solution), in which the first and second solutions are mixed at the time of use. After the first and second solutions are mixed, they may be diluted with water or an aqueous acid solution as needed. The first or second solution may contain all or part of the water used to prepare the etching solution. The first and second solutions may each contain the above-mentioned optional components as needed.

[0031] The pH of the etching solution composition of this disclosure is preferably 1 or less, more preferably 0 or less, even more preferably less than 0, and even more preferably around -1, from the viewpoint of uniform etching of the layer to be etched. The pH of the etching solution composition of this disclosure can preferably be -5 or higher, and more preferably -3 or higher. In this disclosure, the pH of the etching solution composition is the value at 25°C and can be measured using a pH meter, specifically by the method described in the examples.

[0032] The etching solution composition of this disclosure may be stored and supplied in a concentrated state, to the extent that its stability is not impaired. This is preferable in that it can reduce manufacturing and transportation costs. This concentrated solution can then be used in the etching process after being appropriately diluted with water or an aqueous acid solution as needed. The dilution ratio can be, for example, 5 to 100 times.

[0033] [kit] In other embodiments, this disclosure relates to a kit for manufacturing the etching solution composition of this disclosure (hereinafter also referred to as the "Kit of this Disclosure"). Examples of the kits in this disclosure include a two-component etching solution containing, for example, a solution containing nitric acid (solution 1) and a solution containing a polyhydric amine with a number-average molecular weight of 300 or more (solution 2), which are mixed separately and mixed at the time of use. After the first and second solutions are mixed, they may be diluted with water or an aqueous acid solution as needed. The first or second solution may contain all or part of the water used to prepare the etching solution. The first and second solutions may each contain the above-mentioned optional components as needed. According to the kits in this disclosure, an etching solution with excellent storage stability can be prepared.

[0034] [Etched layer] In one or more embodiments, the layer to be etched using the etching solution composition of this disclosure is an etchable layer containing at least one metal. Here, the metal is not particularly limited as long as the effects of this disclosure are achieved, but examples 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, the etching solution composition of this disclosure is preferably used in one or more embodiments to etch a layer to be etched containing at least one metal selected from the group of tungsten, molybdenum, niobium, tantalum, and zirconium, and is suitably used in one or more embodiments to etch a tungsten film or a molybdenum film. That is, in one or more embodiments, the layer to be etched is a tungsten film or a molybdenum film.

[0035] [Etching method] This disclosure relates, in one embodiment, to an etching method (hereinafter also referred to as "the etching method of this disclosure") which includes a step of etching a layer to be etched containing at least one metal using the etching solution composition of this disclosure (hereinafter also referred to as "the etching step of this disclosure"). By using the etching method of this disclosure, in one or more embodiments, the productivity of semiconductor substrates can be improved by using an etching solution with excellent storage stability.

[0036] In the etching process of this disclosure, examples of etching methods include immersion etching and single-wafer etching.

[0037] 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 process of this disclosure (etching temperature) is 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, from the viewpoint of reducing etching unevenness. 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 process of the present disclosure (etching temperature) is 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, from the viewpoint of reducing etching unevenness. 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 process of the present disclosure (etching temperature) is 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, from the viewpoint of reducing etching unevenness. 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 process of the present disclosure (etching temperature) is 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, from the viewpoint of reducing etching unevenness. 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 process of this disclosure (etching temperature) is 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, from the viewpoint of reducing etching unevenness. 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 process of the present disclosure (etching temperature) is 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, from the viewpoint of reducing etching unevenness. 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.

[0038] In the etching process of this disclosure, the etching time can be set, for example, to 1 minute or more and 180 minutes or less.

[0039] In one or more embodiments, the etching method of the present disclosure may include a step of storing, preserving, or transporting the etching solution composition of the present disclosure at a temperature of 10°C or lower.

[0040] The etching solution compositions and etching methods of the present disclosure can be used in one or more embodiments to etch metals in the manufacturing process of electronic devices, particularly semiconductor wafers. The etching solution composition and etching method of this disclosure can be suitably used in the production of semiconductor wafers in one or more embodiments. This improves etching uniformity and enhances productivity and yield. The etching solution compositions and etching methods of the present disclosure can be used in one or more embodiments to etch electrodes in the manufacturing process of electronic devices, particularly semiconductor memories such as non-volatile memories including NAND flash memory. The etching solution composition and etching method of this disclosure can be suitably used in one or more embodiments to produce patterns having a three-dimensional structure. This makes it possible to obtain advanced devices such as high-capacity memory. The etching solution composition and etching method of this disclosure can be used, for example, in etching methods such as those disclosed in Japanese Patent Application Publication No. 2020-145412. [Examples]

[0041] The present disclosure will be specifically described below with reference to examples, but the present disclosure is not limited in any way by these examples.

[0042] 1. Preparation of etching solution (Examples 1-12, Comparative Examples 1-3) The etching solutions (pH:-1) of Examples 1-12 and Comparative Examples 1-3 were obtained by combining nitric acid, other acids (phosphoric acid, acetic acid), polyhydric amines, and water as shown in Table 1. Table 1 shows the proportions (mass %) and effective content of each component in the prepared etching solution. Note that the proportion of water in Table 1 includes the amount of water contained in acidic aqueous solutions, etc.

[0043] The following components were used to prepare the etching solution. Nitric acid [Fujifilm Wako Pure Chemical Industries, Ltd., 70% concentration] Phosphoric acid [manufactured by Phosphorus Chemical Industry Co., Ltd., concentration 85%] Acetic acid [Fujifilm Wako Pure Chemical Industries, Ltd., 100% concentration] Polyethyleneimine [Number average molecular weight 1,800, "Epomin SP-018" manufactured by Nippon Shokubai Co., Ltd.] Water [Ultrapure water produced using a continuous pure water production system (PureConti PC-2000VRL model) and subsystem (MacAce KC-05H model) manufactured by Kurita Water Industries Ltd.]

[0044] 2. Measurement 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 Toa DKK Co., Ltd.), and the value was obtained one minute after immersing the pH meter's electrode in the etching solution.

[0045] 3. Evaluation of etching solution [Presence or absence of turbidity (storage stability)] 20 ml of the etching solution composition immediately after preparation was taken into a sample bottle and visually inspected for turbidity after standing at 1°C for various time periods. A sample was marked with ○ if no turbidity occurred after 48 hours or more, △ if turbidity occurred between 24 and 48 hours, and × if turbidity occurred in 24 hours or less. The results are shown in Table 1.

[0046] [Table 1]

[0047] As shown in Table 1, the amount of nitric acid (mass%) a and the amount of polyhydric amine (mass%) b are a 4 Examples 1 to 12 that satisfy / b ≤ 600 all have a 4 Compared to Comparative Examples 1-3, where the temperature was >600, it was found that turbidity was suppressed even when stored at low temperatures, indicating superior storage stability. [Industrial applicability]

[0048] The etching solution composition of this disclosure has excellent storage stability and is useful in a method for manufacturing high-capacity semiconductor memory.

Claims

1. An etching solution composition for etching a layer to be etched, comprising titanium nitride, alumina, or at least one metal, The etching solution composition comprises nitric acid, a polyhydric amine having a number average molecular weight of 300 or more, and water. The aforementioned polyhydric amine is a branched polyethyleneimine, The amount of water used is 30% by mass or less. The amount of nitric acid (mass%) a and the amount of polyhydric amine with a number average molecular weight of 300 or more (mass%) b are, a 4 An etching solution composition that satisfies the relationship / b ≤ 600.

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

3. The etching solution composition according to claim 2, wherein the acid other than nitric acid is at least one selected from phosphoric acid, acetic acid, methoxyacetic acid, and ethoxyacetic acid.

4. The etching solution composition according to claim 1 or 2, wherein the amount of the polyhydric amine blended is 0.1% by mass or more and 20% by mass or less.

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, aluminum, and iridium.

6. The process includes etching a layer to be etched, which contains titanium nitride, alumina, or at least one metal, using an etching solution composition stored at 10°C or below. The etching solution composition comprises nitric acid, a polyhydric amine having a number average molecular weight of 300 or more, and water. The amount of water in the etching solution composition is 30% by mass or less. An etching method in which the amount (mass%) a of nitric acid in the etching solution composition and the amount (mass%) b of a polyhydric amine having a number average molecular weight of 300 or more satisfy the relationship a 4 / b ≤ 600.

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

8. A method for manufacturing a semiconductor wafer using the etching method of Claim 6.

9. A method for manufacturing a semiconductor wafer using the etching method of claim 7.

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