Etching method

Abstract

In one aspect, provided is an etching method capable of suppressing a variation in rate between an etching rate at the time of initial use of an etching solution and an etching rate at the time of reuse of the etching solution even when the etching solution is reused.SOLUTION: The present disclosure, in one aspect, relates to an etching method including a step of etching a layer to be etched containing a Group 6 element metal using an etching solution containing phosphoric acid, nitric acid, and the following component A, the etching method including a step of adding the following component A to the etching solution before the etching in a case where the etching solution contains a Group 6 element metal. At least one compound selected from a compound having a repeating unit derived from ethyleneimine, a compound having a repeating unit derived from allylamine, and a compound having a repeating unit derived from diallylamine SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to an etching method. [Background technology]

[0002] In the manufacturing process of a semiconductor device, a step is carried out in which a layer to be etched, which contains at least one metal such as tungsten, tantalum, zirconium, hafnium, molybdenum, niobium, ruthenium, osmium, rhenium, rhodium, copper, nickel, cobalt, titanium, titanium nitride, alumina, aluminum, and iridium, is etched and processed into a predetermined pattern shape. In recent years, the semiconductor industry has seen increasing integration density, which has led to demands for more complex and finer wiring. This has led to increased demands for pattern processing techniques and etching solutions, and various etching solutions have been proposed.

[0003] For example, Patent Document 1 proposes an etching solution composition for etching a layer to be etched that contains at least one kind of metal, the etching solution composition including 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. Patent Document 2 proposes a method for producing an etching solution composition for etching a metal film (film to be etched) formed on a substrate, the method comprising a step of filling a container with the etching solution composition using a filling nozzle having a filling port for discharging the etching solution composition, wherein the receding contact angle of the etching solution with respect to the material of the filling port of the filling nozzle is 60° or more and the ratio of the advancing contact angle to the receding contact angle (advancing contact angle / receding contact angle) is 1.4 or less. Claim 3 and other documents in the same document state that the etching solution composition contains phosphoric acid, nitric acid, an organic acid, an etching inhibitor, and water. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2024-37160 [Patent Document 2] Japanese Patent Application Laid-Open No. 2024-37705 Summary of the Invention [Problem to be solved by the invention]

[0005] As an etching solution, a mixed acid aqueous solution containing nitric acid (strong acid aqueous solution) is generally used. Patent Documents 1 and 2 propose adding an etching inhibitor such as polyethyleneimine as an agent for suppressing etching and improving etching selectivity. In an etching solution containing an etching inhibitor, the etching inhibitor interacts with the metal dissolved from the layer to be etched as the etching progresses, so the etching rate increases over time as the etching solution is reused. On the other hand, if an excessive amount of etching inhibitor is present in the etching solution from the beginning (the first etching), etching is excessively suppressed, resulting in a decrease in productivity.

[0006] Therefore, in one aspect, the present disclosure provides an etching method that can suppress the variation in etching rate between the etching rate when the etching liquid is used for the first time and the etching rate when the etching liquid is reused, even when the etching liquid is reused. [Means for solving the problem]

[0007] In one aspect, the present disclosure relates to an etching method comprising the step of etching a layer to be etched that contains a Group 6 element metal using an etching solution containing phosphoric acid, nitric acid, and the following component A, and when the etching solution contains a Group 6 element metal, the etching method further comprises the step of adding the following component A to the etching solution before the etching: Component A: at least one compound selected from the group consisting of a compound having a repeating unit derived from ethyleneimine, a compound having a repeating unit derived from allylamine, and a compound having a repeating unit derived from diallylamine

[0008] In one aspect, the present disclosure relates to a method for manufacturing an electronic component, which includes etching an etching target layer containing a Group 6 element metal using the etching method of the present disclosure. [Effects of the Invention]

[0009] According to one aspect of the present disclosure, an etching method can be provided that can suppress the variation in etching rate between the etching rate when the etching liquid is used for the first time and the etching rate when the etching liquid is reused, even when the etching liquid is reused. DETAILED DESCRIPTION OF THE INVENTION

[0010] As a result of extensive research, the present inventors have found that adding a specific compound (component A) to an etching solution containing a Group 6 element to be reused makes it possible to maintain the etching rate at the time of reuse within an appropriate range, and to suppress the variation in etching rate between the etching rate at the time of initial use and the etching rate at the time of reuse.

[0011] In one aspect, the present disclosure relates to an etching method including a step of etching a layer to be etched that contains a Group 6 element metal using an etching solution containing phosphoric acid, nitric acid, and the following component A (hereinafter also referred to as the "etching step"), and when the etching solution contains the Group 6 element metal, the etching method further includes a step of adding the following component A to the etching solution (hereinafter also referred to as the "adding step") before the etching (hereinafter also referred to as the "etching method of the present disclosure"). Component A: at least one compound selected from the group consisting of a compound having a repeating unit derived from ethyleneimine, a compound having a repeating unit derived from allylamine, and a compound having a repeating unit derived from diallylamine

[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. When an etching solution containing an etching inhibitor such as polyethyleneimine is used, it is believed that the etching rate can be suppressed by a certain amount of the etching inhibitor being adsorbed onto the layer to be etched. However, if the reused etching solution contains a Group 6 element metal dissolved from the layer to be etched, the etching inhibitor interacts with the Group 6 element metal dissolved in the etching solution, making it impossible to maintain the etching rate within an appropriate range when the etching solution is reused. As the number of times the etching solution is reused increases, the etching rate tends to increase over time. Therefore, the present inventors conducted extensive research and found that, instead of adding a large amount of an etching inhibitor to the etching solution before the start of etching (i.e., the etching solution when used for the first time), by adding a specific etching inhibitor (specific compound: component A) to the etching solution containing a Group 6 element metal (molybdenum, etc.) to be reused (i.e., the etching solution when reused), the etching rate when reused can be kept within an appropriate range and the variation in etching rate between the etching rate when the etching solution is used for the first time and the etching rate when the etching solution is reused can be suppressed. However, the present disclosure need not be construed as being limited to these mechanisms.

[0013] [Layer to be etched] In the present disclosure, the layer to be etched is a layer to be etched that contains a Group 6 element metal. Examples of the Group 6 element metal include at least one metal selected from tungsten and molybdenum. In one or more embodiments, the layer to be etched may be a tungsten film (layer) or a molybdenum film (layer).

[0014] [Addition process] In one or more embodiments, the adding step in the etching method of the present disclosure is a step of additionally adding component A to the etching solution before etching when the etching solution contains a Group 6 element metal. Hereinafter, the "addition amount of component A" refers to the amount of component A added in this adding step. In one or more embodiments, the Group 6 element metal contained in the etching solution is derived from the Group 6 element metal contained in the layer to be etched, and in one or more embodiments, is the Group 6 element metal dissolved from the layer to be etched. In one or more embodiments, the Group 6 element metal is at least one selected from tungsten and molybdenum. The Group 6 element metal in the etching solution may be one type or a combination of two or more types. In one or more embodiments, the Group 6 element metal contained in the etching solution is in an ionic state. The concentration (content, dissolved amount) of the Group 6 element metal in the etching solution can be measured using ICP or the like. For example, the content of the Group 6 element metal in the etching solution may be 1 ppm or more, 100 ppm or more, or 1,000 ppm or more in one or more embodiments. In one or more embodiments, the content of the Group 6 element metal in the etching solution is preferably 10,000 ppm or less, more preferably 8,000 ppm or less, and even more preferably 6,000 ppm or less, from the viewpoint of keeping the etching rate at a certain level or less. When two or more types of Group 6 element metals are used in combination, the content of the Group 6 element metals is the total content thereof.

[0015] The amount of component A added in the addition step is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more, based on the total amount of the etching solution, from the viewpoint of suppressing variation in etching rate between the first use and reuse of the etching solution, and from the same viewpoint, is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less. More specifically, the amount of component A added is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.05% by mass or more and 5% by mass or less, and even more preferably 0.1% by mass or more and 3% by mass or less, based on the total amount of the etching solution.

[0016] From the viewpoint of suppressing variation in etching rate between the first use and reuse of the etching solution, the amount of component A added in the addition step is preferably 0.01 or more, more preferably 0.1 or more, even more preferably 0.2 or more, and even more preferably 0.5 or more, as the mass ratio of the amount of component A added to the content of Group 6 element metal in the etching solution after the first use (or before the addition step) (amount of component A added / content of Group 6 element metal), and from the same viewpoint, is preferably 10 or less, more preferably 7 or less, even more preferably 5 or less, and even more preferably 3 or less. More specifically, the amount of component A added is preferably 0.01 or more and 10 or less, or 0.1 or more and 10 or less, more preferably 0.1 or more and 7 or less, more preferably 0.2 or more and 5 or less, and even more preferably 0.5 or more and 3 or less, relative to the content of Group 6 element metal in the etching solution. From the same viewpoint, the amount of component A added in the addition step when the etching solution is reused for the second or subsequent times can be the above-mentioned mass ratio relative to the increased content of the Group 6 element metal in the etching solution since the previous reuse or addition. Alternatively, from the same viewpoint, the amount of component A added in the addition step when the etching solution is reused for the second or subsequent times can be the same as the amount of component A added during the previous reuse or addition.

[0017] In the addition step, the ratio of the amount of component A added to the amount of component A in the etching solution before adding component A (amount of component A added / amount of component A in the etching solution before adding component A) is preferably 0.01 or more, more preferably 0.05 or more, and even more preferably 0.1 or more, from the viewpoint of suppressing variation in etching rate between the first use and reuse of the etching solution, and from the same viewpoint, is preferably 2 or less, more preferably 1.5 or less, and even more preferably 1 or less. More specifically, the ratio (amount of component A added / amount of component A in the etching solution before adding component A) is preferably 0.01 or more and 2 or less, more preferably 0.05 or more and 1.5 or less, and even more preferably 0.1 or more and 1 or less.

[0018] In the adding step, a mixed acid containing phosphoric acid and nitric acid may be added together with component A. That is, in one or more embodiments, the adding step may be a step of adding component A and a mixed acid containing phosphoric acid and nitric acid to an etching solution containing a Group 6 element metal. The mixed acid containing phosphoric acid and nitric acid may contain an organic acid, which will be described later. The content of the mixed acid to be added can be set appropriately.

[0019] In one or more embodiments, the etching method of the present disclosure may further include, before the adding step, a step of measuring the concentration of the Group 6 element metal in the etching solution used in the etching step.

[0020] [Etching process] The etching step in the etching method of the present disclosure is a step of etching a layer to be etched that contains a Group 6 element metal using an etching solution that contains phosphoric acid, nitric acid, and component A.

[0021] In the etching step, examples of the etching method include immersion etching and single wafer etching.

[0022] In one or more embodiments, when the layer to be etched is a tungsten film, the temperature of the etching solution in the etching step of the present disclosure (etching temperature) is, from the viewpoint of uniform etching of the layer to be etched, 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 in the etching step of the present disclosure (etching temperature) is, from the viewpoint of uniform etching of the layer to be etched, 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.

[0023] In the etching step, the etching time can be set to, for example, 1 minute or more and 180 minutes or less.

[0024] In one or more embodiments, the etching step is a step of bringing an etching solution containing phosphoric acid, nitric acid, and component A into contact with a substrate having a metal layer containing a Group 6 element metal. Examples of the substrate having a metal layer containing a Group 6 element metal include a substrate having a tungsten layer and a substrate having a molybdenum layer. Examples of the substrate include a silicon wafer. Therefore, in one or more embodiments, the etching method of the present disclosure is an etching method including the following steps 1 and 2: Step 1: A step of contacting a substrate having a metal layer containing a Group 6 element metal with an etching solution containing phosphoric acid, nitric acid, and component A. Step 2: When the etching solution in Step 1 contains a Group 6 element metal, adding component A to the etching solution before contacting the etching solution.

[0025] [Etching solution] In one or more embodiments, the etching solution used in the etching step contains phosphoric acid, nitric acid, and component A, and does not contain a Group 6 element metal. In one or more embodiments of the present disclosure, the etching solution that does not contain a Group 6 element metal is the etching solution used initially in the etching step (hereinafter also referred to as the "etching solution at the time of first use"). In one or more embodiments, the etching solution used in the etching step contains phosphoric acid, nitric acid, component A, and a Group 6 element metal. In one or more embodiments of the present disclosure, the etching solution containing a Group 6 element metal is an etching solution that has been used one or more times in the etching step (hereinafter also referred to as a "reused etching solution"). Each component contained in the etching solution will be described below.

[0026] (Group 6 metals in etching solution) When the etching solution contains a Group 6 element metal, the content of the Group 6 element metal in the etching solution used in the etching step (the etching solution when reused) is, in one or more embodiments, 1 ppm or more, 100 ppm or more, or 1,000 ppm or more. In one or more embodiments, the content of the Group 6 element metal in the etching solution when reused is preferably 10,000 ppm or less, more preferably 8,000 ppm or less, and even more preferably 6,000 ppm or less, from the viewpoint of keeping the etching rate at a certain level or less.

[0027] (phosphoric acid in etching solution) The amount of phosphoric acid in the etching solution used in the etching step (the etching solution used for the first time and the etching solution used for reuse) is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more, from the viewpoint of uniform etching of the layer to be etched, and from the same viewpoint, is preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 80% by mass or less. More specifically, the amount of phosphoric acid in the etching solution used in the etching step is preferably 40% by mass or more and 90% by mass or less, more preferably 50% by mass or more and 85% by mass or less, and even more preferably 60% by mass or more and 80% by mass or less.

[0028] (nitric acid in etching solution) The amount of nitric acid in the etching solution used in the etching step (the etching solution used for the first time and the etching solution used for reuse) is preferably 0.1% by mass or more or 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 2% 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 5% by mass or less, from the viewpoint of uniform etching of the layer to be etched. More specifically, the amount of nitric acid in the etching solution used in the etching step is preferably 0.1% by mass or more to 20% by mass or 0.5% by mass or more to 20% by mass or more, more preferably 1% by mass or more to 10% by mass or more, and even more preferably 2% by mass or more to 5% by mass or less.

[0029] (Component A in the etching solution: Compound) Component A contained in the etching solution used in the etching step (the etching solution used for the first time and the etching solution used for reuse) is at least one compound selected from compounds having a repeating unit derived from ethyleneimine, compounds having a repeating unit derived from allylamine, and compounds having a repeating unit derived from diallylamine. Component A may be used alone or in combination of two or more. Examples of the compound having a repeating unit derived from ethyleneimine include polyethyleneimine (PEI). Examples of the compound having a repeating unit derived from allylamine include allylamine hydrochloride polymers and allylamine polymers. Examples of compounds having a repeating unit derived from diallylamine include diallylamine polymers and diallylamine / sulfur dioxide copolymers.

[0030] The number average molecular weight of the compound having a repeating unit derived from ethyleneimine is preferably 300 or more, more preferably 600 or more, still more preferably 1,200 or more, from the viewpoint of uniform etching of the etched layer in one or more embodiments, and preferably 100,000 or less, more preferably 10,000 or less, still more preferably 5,000 or less, from the viewpoint of viscosity. More specifically, the number average molecular weight of the compound having a repeating unit derived from ethyleneimine is preferably 300 or more and 100,000 or less, more preferably 600 or more and 10,000 or less, still more preferably 1,200 or more and 5,000 or less. The weight average molecular weight of the compound having a repeating unit derived from allylamine is preferably 1,000 or more, more preferably 2,000 or more, still more preferably 3,000 or more, from the viewpoint of uniform etching of the etched layer in one or more embodiments, and preferably 50,000 or less, more preferably 10,000 or less, still more preferably 7,000 or less. More specifically, the weight average molecular weight of the compound having a repeating unit derived from allylamine is preferably 1,000 or more and 50,000 or less, more preferably 2,000 or more and 10,000 or less, still more preferably 3,000 or more and 7,000 or less. The weight average molecular weight of the compound having a repeating unit derived from diallylamine is preferably 1,000 or more, more preferably 2,000 or more, still more preferably 3,000 or more, from the viewpoint of uniform etching of the etched layer in one or more embodiments, and preferably 50,000 or less, more preferably 10,000 or less, still more preferably 7,000 or less. More specifically, the weight average molecular weight of the compound having a repeating unit derived from diallylamine is preferably 1,000 or more and 50,000 or less, more preferably 2,000 or more and 10,000 or less, still more preferably 3,000 or more and 7,000 or less.

[0031] Examples of the method for measuring the average molecular weight of Component A of the present disclosure are shown below. <GPC conditions (compound having a repeating unit derived from ethyleneimine, compound having a repeating unit derived from allylamine, and compound having a repeating unit derived from diallylamine)> Sample solution: adjusted to a concentration of 0.1 wt% Instrument / detector: HLC-8320GPC (integrated GPC) manufactured by Tosoh Corporation Column: α-M + α-M (Tosoh Corporation) Eluent: 0.15mol / L Na2SO4,1% CH3COOH / water Column temperature: 40℃ Flow rate: 1.0mL / min Sample injection volume: 100 μL Standard polymer: pullulan with known molecular weight (Shodex P-5, P-50, P-200, P-800)

[0032] The amount of component A in the etching solution used in the etching step at the time of initial use is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more, from the viewpoint of maintaining an etching rate at or below a certain level. Also, from the viewpoint of maintaining an etching rate at or above a certain level, the amount is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less. The amount of component A in the etching solution used in the etching is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.05% by mass or more and 5% by mass or less, and even more preferably 0.1% by mass or more and 3% by mass or less. When component A is a combination of two or more types, the amount of component A is the total amount thereof. In the etching solution to be used in the etching step when reused, the additional amount of component A described above is added to the blended amount of component A described above in the adding step.

[0033] (water) In one or more embodiments, the etching solution used in the etching step (the etching solution used for the first time and the etching solution used for reuse) further contains water. Examples of water contained in the etching solution of the present disclosure include distilled water, ion-exchanged water, pure water, and ultrapure water. The amount of water in the etching solution used in the etching step (the etching solution used for the first time and the etching solution used for reuse) 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 uniform etching of the layer to be etched, and from the same viewpoint, 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 used in the etching step 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.

[0034] (organic acid) In one or more embodiments, the etching solution used in the etching step (the etching solution used for the first time and the etching solution used for reuse) may further contain an organic acid. Examples of organic acids include at least one selected from the group consisting of 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. From the viewpoint of uniform etching of the layer to be etched, the organic acid is preferably a monovalent organic acid having 1 to 10 carbon atoms, more preferably a monovalent carboxylic acid having 1 to 10 carbon atoms, and even more preferably one containing acetic acid. One organic acid may be used alone, or two or more organic acids may be used in combination.

[0035] The amount of organic acid in the etching solution used in the etching step (the etching solution used for the first time and the etching solution used for reuse) is preferably 2% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, from the viewpoint of uniform etching of the layer to be etched. From the same viewpoint, it is preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less. More specifically, the amount of organic acid in the etching solution used in the etching step is preferably 2% by mass or more and 60% by mass or less, more preferably 3% by mass or more and 50% by mass or less, and even more preferably 5% by mass or more and 40% by mass or less. When two or more organic acids are used in combination, the amount of organic acid is the total amount of the organic acids.

[0036] The total amount of phosphoric acid, nitric acid, and organic acid in the etching solution used in the etching step (the etching solution used for the first time and the etching solution used for reuse) is preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more, from the viewpoint of uniform etching of the layer to be etched, and from the same viewpoint, is preferably 99.9% by mass or less, more preferably 99% by mass or less, and even more preferably 98% by mass or less. The total amount of phosphoric acid, nitric acid, and organic acid in the etching solution used in the etching step is preferably 70% by mass or more and 99.9% by mass or less, more preferably 75% by mass or more and 99% by mass or less, and even more preferably 80% by mass or more and 98% by mass or less.

[0037] In one or more embodiments, the acid contained in the etching solution used in the etching step (the etching solution used for the first time and the etching solution used for reuse) is an acid containing phosphoric acid, nitric acid, and an organic acid, and from the viewpoint of improving the etching rate, it is preferably an acid containing phosphoric acid, nitric acid, and acetic acid, and more preferably a mixed acid containing phosphoric acid, nitric acid, and acetic acid. In the present disclosure, in one or more embodiments, the "mixed acid" refers to a mixed acid containing phosphoric acid and nitric acid, in one or more other embodiments, a mixed acid containing phosphoric acid, nitric acid, and an organic acid, in one or more other embodiments, a mixed acid containing phosphoric acid, nitric acid, and acetic acid, and in one or more other embodiments, a mixed acid consisting of phosphoric acid, nitric acid, and acetic acid.

[0038] (Other ingredients) The etching solution used in the etching step (the etching solution used for the first time and the etching solution used for reuse) may further contain other components within the scope that does not impair the effects of the present disclosure. Examples of other components include inorganic acids other than phosphoric acid and nitric acid, chelating agents, surfactants, solubilizing agents, preservatives, rust inhibitors, disinfectants, antibacterial agents, antioxidants, etc.

[0039] In one or more embodiments, the etching solution for first use can be obtained by blending phosphoric acid, nitric acid, component A, water, and, if desired, the optional components (organic acid, other components) described above by a known method. Thus, in one or more embodiments, the method for producing the etching solution for first use can include at least a step of blending phosphoric acid, nitric acid, component A, and water. In one or more embodiments, the reused etching solution can be obtained by using the first-use etching solution once or more times for etching. In the present disclosure, "blending at least phosphoric acid, nitric acid, component A, and water" includes, in one or more embodiments, simultaneously or sequentially mixing phosphoric acid, nitric acid, component A, water, and, if necessary, the optional components described above. The order of mixing is not particularly limited. The blending can be carried out using a mixer such as a propeller-type agitator, a pump-based liquid circulation agitator, a homomixer, a homogenizer, an ultrasonic disperser, or a wet ball mill. The preferred blending amounts of each component in the method for producing the etching solution for the first use can be the same as the preferred blending amounts of each component in the etching solution used in the etching step described above.

[0040] In the present disclosure, the "amount of each component of the etching solution" refers, in one or more embodiments, to the amount of each component in the etching solution 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 amount of each component in the etching solution used in the etching step can be considered to be the content of each component in the etching solution used in the etching step. However, if there is an effect of neutralization, the amount of each component may differ from the content.

[0041] The etching solution for first use may be a so-called one-component type, in which all components are premixed and supplied to the market, or a so-called two-component type, in which components are mixed at the time of use. Examples of two-component etching solutions include those in which water is separated into a first component and a second component, and phosphoric acid, nitric acid, and component A are contained in either or both of the first and second components, and the first and second components are mixed at the time of use. The first and second components may each contain the optional components described above (organic acids, other components) as necessary.

[0042] The pH of the etching solution used in the etching step (the etching solution used for the first time and the etching solution used for reuse) 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 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 is a value at 25°C and can be measured using a pH meter, specifically, by the method described in the Examples.

[0043] The etching solution for the first use may be stored and supplied in a concentrated state as long as its storage stability is not impaired. This is preferable because it reduces production and transportation costs. The concentrated solution can then be diluted appropriately with water or an aqueous acid solution as needed for use in the etching process. The dilution ratio can be, for example, 3 to 100 times.

[0044] In one or more embodiments, 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 method of the present disclosure can be suitably used in the production of semiconductor wafers, thereby improving the uniformity of the etched layer and increasing productivity and yield. In one or more embodiments, 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 method of the present disclosure can be suitably used to fabricate a pattern having a three-dimensional structure, thereby enabling the production of advanced devices such as high-capacity memories. The etching method of the present disclosure can be used, for example, in an etching method such as that disclosed in JP 2020-145412 A.

[0045] [Electronic component manufacturing method] 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"), which includes etching an etching target layer containing a Group 6 element metal using the etching method of the present disclosure. That is, in one or more embodiments, the method for producing an electronic component according to the present disclosure includes a step of etching a layer to be etched that contains a Group 6 element metal using an etching solution containing phosphoric acid, nitric acid, and component A, and when the etching solution contains a Group 6 element metal, the method further includes a step of adding component A to the etching solution before the etching. Examples of electronic components include at least one substrate selected from semiconductor substrates (semiconductor wafers), substrates for liquid crystal displays, substrates for plasma displays, substrates for FEDs (Field Emission Displays), substrates for optical disks, substrates for magnetic disks, substrates for magneto-optical disks, substrates for photomasks, ceramic substrates, and substrates for solar cells; and semiconductor memories such as nonvolatile memories including NAND flash memories. The etching method and conditions in the method for producing an electronic component according to the present disclosure include the same etching method and conditions as those in the etching step in the etching method according to the present disclosure described above. The method for adding component A in the method for producing an electronic component according to the present disclosure includes the same addition method as those in the addition step in the etching method according to the present disclosure described above. The layer to be etched includes the layer to be etched described above. [Example]

[0046] The present disclosure will be specifically described below using examples, but the present disclosure is not limited to these examples in any way.

[0047] 1. Preparation of Etching Solution (Examples 1 to 3) Mixed acid (phosphoric acid / acetic acid / nitric acid), water, and component A (PEI) were blended, and molybdenum (Mo) powder was added and thoroughly dissolved at 60°C until the solution became transparent, yielding a molybdenum-containing solution. The amount of Mo dissolved (ppm) in the molybdenum-containing solution is shown in Table 1. Note that 1 ppm is 0.0001% by mass. Thereafter, component A (PEI) was added to the liquid containing molybdenum (addition step) to obtain etching solutions (pH: -1) of Examples 1 to 3. As shown in Table 1, the amount of PEI added in Examples 1 to 3 was 0.05 mass % or 0.2 mass % relative to the liquid in which 500 ppm or 5000 ppm of molybdenum powder was dissolved. (Comparative Examples 1 and 2) A mixed acid (phosphoric acid / acetic acid / nitric acid), water, and component A (PEI) were mixed, molybdenum (Mo) powder was added, and the mixture was thoroughly dissolved at 60°C until the mixture became transparent, thereby obtaining a molybdenum-containing liquid. In Comparative Examples 1 and 2, this molybdenum-containing liquid was used as an etching liquid (pH: -1). In Comparative Examples 1 and 2, component A (PEI) was not added. (Reference example 1) An etching solution (pH: -1) of Reference Example 1 was obtained by mixing a mixed acid (phosphoric acid / acetic acid / nitric acid), water, and component A (PEI). The amount of each component (mass %, active content) in each etching solution prepared as described above is shown in Table 1. The mass ratio of the mixed acid is calculated by mass, and the amount of water included includes the amount of water contained in the acid aqueous solution, etc. The etching solution in Reference Example 1 is assumed to be an etching solution used for the first time, while Examples 1 to 3 and Comparative Examples 1 and 2 are assumed to be etching solutions used for reuse.

[0048] The following components were used to prepare the etching solution. Phosphoric acid [Rinkagaku Kogyo Co., Ltd., concentration 85%] Nitric acid [Fujifilm Wako Pure Chemical Corporation, concentration 70%] 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.] Water [ultrapure water produced using a continuous pure water production system (Pure Conti PC-2000VRL) and a subsystem (MacAce KC-05H) manufactured by Kurita Water Industries Ltd.] Molybdenum powder ["Mo-3K" manufactured by Nippon Shinkinzoku Co., Ltd.]

[0049] 2. Measuring the pH of the 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.

[0050] 3.Evaluation of etching solutions [Evaluation of etching rate of molybdenum plate] A molybdenum plate, 2 cm long, 2 cm wide, and 0.1 mm thick, whose weight had been measured in advance, was immersed in the etching solution prepared for each composition, and the molybdenum plate was etched at 40°C for 30 minutes. After rinsing with water, the molybdenum plate was again weighed, and the difference between the weights was taken as the amount of etching. A precision balance was used to measure the weight. The etching rate was then calculated using the following formula: Etching rate (nm / min) = Etching amount (g) × 10 7 / (10.28(g / cm 3 ) × 2 × 2) / etching time (min) / 2

[0051] [Table 1]

[0052] As shown in Table 1, in Examples 1 and 2 in which PEI was added in the addition step, the increase in etching rate was suppressed compared to Comparative Examples 1 and 2 in which PEI was not added. Therefore, it was found that by adding component A such as PEI to an etching solution containing a Group 6 element metal such as Mo, the etching rate can be maintained, that is, the variation in rate between the etching rate when the etching solution is used for the first time (Reference Example 1) and the etching rate when the etching solution is reused (Examples 1 and 2) can be suppressed. Furthermore, when Example 3 is compared with Comparative Example 1, even though the total amount of PEI in the etching solution used for etching (0.2 mass%) is the same, the increase in etching rate was suppressed in Example 3, in which PEI was added in the addition step, compared to Comparative Example 1, in which PEI was not added in the addition step. [Industrial Applicability]

[0053] The etching method of the present disclosure can maintain the etching rate even when reused, and is therefore useful in manufacturing methods for large-capacity semiconductor memories.

Claims

1. An etching method comprising a step of etching a layer to be etched, the layer containing a Group 6 element metal, using an etching solution containing phosphoric acid, nitric acid, and the following component A: When the etching solution contains a Group 6 element metal, the etching method comprises the step of adding the following component A to the etching solution before the etching: Component A: at least one compound selected from the group consisting of a compound having a repeating unit derived from ethyleneimine, a compound having a repeating unit derived from allylamine, and a compound having a repeating unit derived from diallylamine

2. 2. The etching method according to claim 1, wherein the content of the Group 6 element metal in the etching solution is 1 ppm or more.

3. 2. The etching method according to claim 1, wherein the Group 6 element metal is at least one selected from the group consisting of tungsten and molybdenum.

4. 2. The etching method according to claim 1, wherein the amount of component A in the etching solution used in the etching is 0.01% by mass or more and 10% by mass or less.

5. 2. The etching method according to claim 1, wherein the amount of component A added in the step of adding component A is 0.01 mass % or more and 10 mass % or less with respect to the total amount of the etching solution.

6. 2. The etching method according to claim 1, wherein the amount of Component A added in the step of adding Component A is 0.01 to 10 times the content of the Group 6 element metal in the etching solution.

7. 2. The etching method according to claim 1, wherein in the step of adding component A, a ratio of the amount of component A added to the amount of component A blended in the etching solution before adding component A is 0.01 or more and 2 or less.

8. 2. The etching method according to claim 1, wherein the amount of phosphoric acid contained in the etching solution used in the etching is 40% by mass or more and 90% by mass or less.

9. 2. The etching method according to claim 1, wherein the amount of nitric acid contained in the etching solution used in the etching is 0.1% by mass or more and 20% by mass or less.

10. the etching solution further comprises water; 2. The etching method according to claim 1, wherein the amount of water contained in the etching solution used in the etching is 2% by mass or more and 30% by mass or less.

11. the etching solution further contains an organic acid; 2. The etching method according to claim 1, wherein the amount of the organic acid contained in the etching solution used in the etching is 2% by mass or more and 60% by mass or less.

12. 12. The etching method according to claim 11, wherein the total amount of phosphoric acid, nitric acid, and organic acid in the etching solution used in the etching is 70% by mass or more and 99.9% by mass or less.

13. A method for manufacturing an electronic component, comprising etching a layer to be etched containing a Group 6 element metal by using the etching method according to claim 1 .