Etching method

Abstract

One mode of the present invention provides an etching method that, even when an etching liquid is re-used, can suppress rate variability between the etching rate when the etching liquid is used for the first time and the etching rate when the etching liquid is re-used.　In one mode, the present disclosure pertains to an etching method comprising a step for etching an etching target layer containing a group-6 element metal, by using an etching liquid containing phosphoric acid, nitric acid, and the following component A. If the etching liquid contains a group-6 element metal, the etching method comprises a step for adding the following component A to the etching liquid before performing the etching. Component A: 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.

Description

Etching Method

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

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

[0003] For example, Japanese Patent Laid-Open Publication No. 2024-37160 (Patent Document 1) proposes an etching solution composition for etching a layer to be etched containing 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. Japanese Patent Laid-Open Publication No. 2024-37705 (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 filling the etching solution composition into a container 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 sections of this document state that the etching solution composition contains phosphoric acid, nitric acid, an organic acid, an etching inhibitor, and water.

[0004] 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, wherein when the etching solution contains the 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 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.

[0005] 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.

[0006] As an etching solution, a mixed acid aqueous solution (strong acid aqueous solution) containing nitric acid is commonly used. Patent Documents 1 and 2 propose blending 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 etching progresses, so the etching rate increases over time as the number of times the etching solution is reused increases. 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.

[0007] 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.

[0008] 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.

[0009] 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.

[0010] In one aspect, the present disclosure relates to an etching method (hereinafter also referred to as the "etching method of the present disclosure") that includes a step of etching a layer to be etched that contains 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 includes a step of adding the following component A to the etching solution (hereinafter also referred to as the "addition step") before the etching: Component A: 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.

[0011] Although the details of the mechanism by which the effects of the present disclosure are manifested are not clear, it is speculated 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 the etching inhibitor adsorbing a certain amount to 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, as a result of extensive research, the present inventors have found that, rather than adding a large amount of etching inhibitor to the etching solution before the start of etching (i.e., the etching solution 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 (e.g., molybdenum) to be reused (i.e., the etching solution used for the first time), the etching rate when reused can be maintained 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.

[0012] [Layer to be etched] In the present disclosure, the layer to be etched is a layer to be etched containing 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).

[0013] [Addition Step] In one or more embodiments, the addition step in the etching method of the present disclosure is a step of adding additional 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 when the additional component A is added in this addition 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 combined, the content of the Group 6 element metals is the total content thereof.

[0014] 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, relative to the total amount of the etching solution, from the viewpoint of suppressing variation in the 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, relative to the total amount of the etching solution.

[0015] From the viewpoint of suppressing variation in the 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.

[0016] 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 the 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.

[0017] 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.

[0018] In one or more embodiments, the etching method of the present disclosure may further include a step of measuring the concentration of the Group 6 element metal in the etching solution used in the etching step, before the addition step.

[0019] [Etching Step] 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.

[0020] In the etching step, examples of the etching method include immersion etching and single wafer etching.

[0021] In one or more embodiments, when the layer to be etched is a tungsten film, the temperature of the etching solution (etching temperature) in the etching step of the present disclosure 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 (etching temperature) in the etching step of the present disclosure 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.

[0022] In the etching step, the etching time can be set to, for example, 1 minute or more and 180 minutes or less.

[0023] In one or more embodiments, the etching step is a step of contacting an etching solution containing phosphoric acid, nitric acid, and component A with a substrate having a metal layer containing a Group 6 element metal. Examples of substrates having a metal layer containing a Group 6 element metal include substrates having a tungsten layer and substrates having a molybdenum layer. Examples of substrates include silicon wafers. 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 an etching solution containing phosphoric acid, nitric acid, and component A with a substrate having a metal layer containing a Group 6 element metal; and Step 2: When the etching solution in Step 1 contains a Group 6 element metal, a step of adding component A to the etching solution before contacting the etching solution.

[0024] [Etching Solution] In one or more embodiments, the etching solution used in the etching step contains phosphoric acid, nitric acid, and component A, but 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 that contains a Group 6 element metal is the etching solution that has been used one or more times in the etching step (hereinafter also referred to as the "etching solution at the time of reuse"). Hereinafter, each component contained in the etching solution will be described.

[0025] (Group 6 element metal 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 (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, from the viewpoint of keeping the etching rate at a certain level or less, preferably 10,000 ppm or less, more preferably 8,000 ppm or less, and even more preferably 6,000 ppm or less.

[0026] (Phosphoric Acid in Etching Solution) The amount of phosphoric acid in the etching solution used in the etching step (the etching solution at the time of initial use and the etching solution at the time of 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.

[0027] (Nitric Acid in Etching Solution) The amount of nitric acid in the etching solution used in the etching step (the etching solution at the time of initial use and the etching solution at the time of reuse) is preferably 0.1 mass % or more or 0.5 mass % or more, more preferably 1 mass % or more, and even more preferably 2 mass % or more, from the viewpoint of improving the etching rate, and is preferably 20 mass % or less, more preferably 10 mass % or less, and even more preferably 5 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 mass % or more and 20 mass % or less, or 0.5 mass % or more and 20 mass % or less, more preferably 1 mass % or more and 10 mass % or less, and even more preferably 2 mass % or more and 5 mass % or less.

[0028] (Component A in Etching Solution: Compound) Component A contained in the etching solution used in the etching step (the etching solution at the time of initial use and the etching solution at the time of reuse) is 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. 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 polymer, allylamine polymer, etc. Examples of the compound having a repeating unit derived from diallylamine include diallylamine polymer, diallylamine / sulfur dioxide copolymer, etc.

[0029] In one or more embodiments, 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, and even more preferably 1,200 or more, from the viewpoint of uniform etching of the layer to be etched. From the viewpoint of viscosity, it is preferably 100,000 or less, more preferably 10,000 or less, and even more preferably 5,000 or less. 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, and even more preferably 1,200 or more and 5,000 or less. In one or more embodiments, 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, and even more preferably 3,000 or more, and preferably 50,000 or less, more preferably 10,000 or less, and even more preferably 7,000 or less, from the viewpoint of uniform etching of the layer to be etched. More specifically, the weight-average molecular weight of the compound having a repeating unit derived from allylamine is preferably 1,000 to 50,000, more preferably 2,000 to 10,000, and even more preferably 3,000 to 7,000. In one or more embodiments, from the viewpoint of uniform etching of the layer to be etched, 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, and even more preferably 3,000 or more, and is preferably 50,000 or less, more preferably 10,000 or less, and even 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 to 50,000, more preferably 2,000 to 10,000, and even more preferably 3,000 to 7,000.

[0030] An example of a method for measuring the average molecular weight of component A of the present disclosure is shown below. <GPC conditions (compounds having repeating units derived from ethyleneimine, compounds having repeating units derived from allylamine, and compounds having repeating units derived from diallylamine)> 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 NaSO, 1% CHCOOH / water Column temperature: 40°C Flow rate: 1.0 mL / min Sample solution injection amount: 100 μL Standard polymer: pullulan with known molecular weight (Shodex P-5, P-50, P-200, P-800)

[0031] 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. 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 used in the etching step at the time of reuse, the additional amount of component A described above is added to the amount of component A described above in the addition step.

[0032] (Water) In one or more embodiments, the etching solution used in the etching step (the etching solution at the time of initial use and the etching solution at the time of 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. From the viewpoint of uniform etching of the layer to be etched, the amount of water in the etching solution used in the etching step (the etching solution at the time of initial use and the etching solution at the time of 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 same viewpoint, 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 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.

[0033] (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) can further contain an organic acid. Examples of organic acids include 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. The organic acid may be used alone or in combination of two or more types.

[0034] 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, and from the same viewpoint, 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.

[0035] The total amount of phosphoric acid, nitric acid, and organic acid in the etching solution used in the etching step (the etching solution at the time of initial use and the etching solution at the time of 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.

[0036] In one or more embodiments, the acid contained in the etching solution used in the etching step (the etching solution at the time of initial use and the etching solution at the time of reuse) is an acid containing phosphoric acid, nitric acid, and an organic acid. From the viewpoint of improving the etching rate, the acid is preferably an acid containing phosphoric acid, nitric acid, and acetic acid, and more preferably a mixed acid consisting of phosphoric acid, nitric acid, and acetic acid. In the present disclosure, the term "mixed acid" refers to a mixed acid containing phosphoric acid and nitric acid in one or more embodiments, a mixed acid containing phosphoric acid, nitric acid, and an organic acid in one or more embodiments, a mixed acid containing phosphoric acid, nitric acid, and acetic acid in one or more embodiments, and a mixed acid consisting of phosphoric acid, nitric acid, and acetic acid in one or more embodiments.

[0037] (Other Components) 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 a range 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.

[0038] 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 using a known method. Therefore, in one or more embodiments, the method for producing the etching solution for first use can include a step of blending at least phosphoric acid, nitric acid, component A, and water. In one or more embodiments, the etching solution for reuse can be obtained by using the etching solution for first use once or multiple times for etching. In one or more embodiments, the phrase "blending at least phosphoric acid, nitric acid, component A, and water" in the present disclosure includes 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 performed using a mixer such as a propeller-type agitator, a pump for liquid circulation agitation, 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.

[0039] 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 used in the etching step, i.e., the amount of each component in the etching solution at the time of starting use in the etching process (at the time of use). In one or more embodiments, the amount of each component in the etching solution 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.

[0040] 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.

[0041] 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.

[0042] The etching solution for initial 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.

[0043] 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 manufacture of semiconductor wafers. This improves the uniformity of the etched layer, thereby improving 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 manufacture patterns having three-dimensional structures. This allows for the production of advanced devices such as large-capacity memories. The etching method of the present disclosure can be used, for example, in etching methods such as those disclosed in JP 2020-145412 A.

[0044] [Method for Manufacturing Electronic Components] In one aspect, the present disclosure relates to a method for manufacturing an electronic component (hereinafter also referred to as the "method for manufacturing an electronic component of the present disclosure"), which includes etching a layer to be etched containing a Group 6 element metal using the etching method of the present disclosure. That is, in one or more embodiments, the method for manufacturing an electronic component of the present disclosure includes 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 component A. If 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; semiconductor memories such as nonvolatile memories including NAND flash memories; and the like. The etching method and conditions for the method for manufacturing an electronic component of the present disclosure include the same etching method and etching conditions as those for the etching step in the etching method of the present disclosure described above. In the method for producing an electronic component according to the present disclosure, the method for adding Component A may be the same as the adding method used in the etching method according to the present disclosure. The layer to be etched may be the layer to be etched described above.

[0045] The present disclosure further relates to one or more of the following embodiments. <1> An etching method comprising the step of etching a layer to be etched, which contains 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 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> The etching method according to <1>, wherein the content of the Group 6 element metal in the etching solution is 1 ppm or more, or 100 ppm or more, or 1,000 ppm or more. <3> The etching method according to <1> or <2>, wherein the content of the Group 6 element metal in the etching solution is 10,000 ppm or less, or 8,000 ppm or less, or 6,000 ppm or less. <4> The etching method according to any one of <1> to <3>, wherein the Group 6 element metal is at least one selected from tungsten and molybdenum. <5> The etching method according to any one of <1> to <4>, wherein the blending amount of component A in the etching solution used in the etching is 0.01 mass% or more and 10 mass% or less. <6> The etching method according to any one of <1> to <5>, wherein the blending amount of component A in the etching solution used in the etching is 0.01 mass% or more, or 0.05 mass% or more, or 0.1 mass% or more, and 10 mass% or less, or 5 mass% or less, or 3 mass% or less. <7> The etching method according to any one of <1> to <6>, wherein the addition amount of component A in the step of adding component A is 0.01 mass% or more and 10 mass% or less, relative to the total amount of the etching solution. <8> The etching method according to any one of <1> to <7>, wherein the amount of component A added in the step of adding component A is 0.01 mass% or more, or 0.05 mass% or more, or 0.1 mass% or more, and 10 mass% or less, or 5 mass% or less, or 3 mass% or less, relative to the total amount of the etching solution.<9> The etching method according to any one of <1> to <8>, wherein the amount of component A added in the step of adding component A is 0.1 or more and 10 or less, relative to the content of the Group 6 element metal in the etching solution. <10> The etching method according to any one of <1> to <9>, wherein the amount of component A added in the step of adding component A is 0.01 or more, or 0.1 or more, or 0.2 or more, or 0.5 or more, and 10 or less, or 7 or less, or 5 or less, or 3 or less, relative to the content of the Group 6 element metal in the etching solution. <11> The etching method according to any one of <1> to <10>, wherein the ratio of the amount of component A added in the step of adding component A to the amount of component A in the etching solution before adding component A is 0.01 or more and 2 or less. <12> The etching method according to any one of <1> to <11>, wherein in the step of adding component A, the ratio of the amount of component A added to the amount of component A in the etching solution before adding component A is 0.01 or more, or 0.05 or more, or 0.1 or more, and 2 or less, or 1.5 or less, or 1 or less. <13> The etching method according to any one of <1> to <12>, wherein the amount of phosphoric acid in the etching solution used in the etching is 40% by mass or more and 90% by mass or less. <14> The etching method according to any one of <1> to <13>, wherein the amount of phosphoric acid in the etching solution used in the etching is 40% by mass or more, or 50% by mass or more, or 60% by mass or more, and 90% by mass or less, or 85% by mass or less, or 80% by mass or less. <15> The etching method according to any one of <1> to <14>, wherein the amount of nitric acid in the etching solution used in the etching is 0.5% by mass or more and 20% by mass or less. <16> The etching method according to any one of <1> to <15>, wherein the amount of nitric acid in the etching solution used in the etching is 0.1% by mass or more, or 0.5% by mass or more, or 1% by mass or more, or 2% by mass or more, and is 20% by mass or less, or 10% by mass or less, or 5% by mass or less.<17> The etching method according to any one of <1> to <16>, wherein the etching solution further contains water, and the amount of water in the etching solution used in the etching is 2% by mass or more and 30% by mass or less. <18> The etching method according to any one of <1> to <17>, wherein the etching solution further contains an organic acid, and the amount of organic acid in the etching solution used in the etching is 2% by mass or more and 60% by mass or less. <19> The etching method according to any one of <1> to <18>, wherein the etching solution further contains an organic acid, and the organic acid is 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. <20> The etching method according to any one of <1> to <19>, wherein the etching solution further contains an organic acid, and the amount of the organic acid in the etching solution used in the etching is 2% by mass or more, or 3% by mass or more, or 5% by mass or more, and 60% by mass or less, or 50% by mass or less, or 40% by mass or less. <21> The etching method according to any one of <1> to <20>, 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, or 99.9% by mass or less. <22> The etching method according to any one of <1> to <21>, 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, or 75% by mass or more, or 80% by mass or more, and 99.9% by mass or less, or 99% by mass or less, or 98% by mass or less.<23> An etching method comprising the step of etching a layer to be etched containing 1 ppm or more and 10,000 ppm or less of molybdenum or tungsten, using an etching solution containing phosphoric acid, nitric acid, acetic acid, and the following component A, wherein the total blending amount of the phosphoric acid, nitric acid, and organic acid is 70 mass% or more and 99.9 mass% or less, wherein when the etching solution contains molybdenum or tungsten, the etching method comprises the step of adding the following component A to the etching solution in an amount of 0.01 mass% or more and 10 mass% or less, relative to the total amount of the etching solution, before the etching: Component A: 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. <24> A method for producing an electronic component, comprising etching a layer to be etched containing a Group 6 element metal, using the etching method according to any one of <1> to <23>.

[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) A mixed acid (phosphoric acid / acetic acid / nitric acid), water, and Component A (PEI) were blended, and molybdenum (Mo) powder was added. This was 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. Component A (PEI) was then added to the molybdenum-containing solution (addition step), yielding the 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% by mass or 0.2% by mass relative to the solution in which 500 ppm or 5,000 ppm of molybdenum powder was dissolved. Comparative Examples 1 and 2: Mixed acid (phosphoric acid / acetic acid / nitric acid), water, and component A (PEI) were blended, and molybdenum (Mo) powder was added. The mixture was thoroughly dissolved at 60°C until transparent, yielding a molybdenum-containing solution. In Comparative Examples 1 and 2, this molybdenum-containing solution was used as an etching solution (pH: -1). Note that component A (PEI) was not added in Comparative Examples 1 and 2. Reference Example 1: Mixed acid (phosphoric acid / acetic acid / nitric acid), water, and component A (PEI) were blended to obtain the etching solution (pH: -1) of Reference Example 1. The blending amounts (mass %, active content) of each component in each etching solution prepared as described above are shown in Table 1. The mass ratio of the mixed acid is calculated by mass, and the blending amount of water includes the blending amount of water contained in the acid aqueous solution, etc. Note that the etching solution of Reference Example 1 is intended to be an etching solution used for the first time, while Examples 1 to 3 and Comparative Examples 1 and 2 are intended to be reused etching solutions.

[0048] The following components were used to prepare the etching solution: Phosphoric acid [manufactured by 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 (PureConti PC-2000VRL type) and subsystem (Macace KC-05H type) manufactured by Kurita Water Industries Ltd.] Molybdenum powder ["Mo-3K" manufactured by Japan New Metals Co., Ltd.]

[0049] 2. Measurement of 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.

[0050] 3. Evaluation of Etching Solution [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 with each composition, and the molybdenum plate was etched at 40°C for 30 minutes. After washing with water, the molybdenum plate was again weighed, and the difference 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 ) x 2 x 2) / etching time (minutes) / 2

[0051]

[0052] As shown in Table 1, Examples 1 and 2, in which PEI was added in the addition step, showed a more suppressed increase in the etching rate than Comparative Examples 1 and 2, in which no PEI was added. Therefore, it was found that adding Component A, such as PEI, to an etching solution containing a Group 6 element metal, such as Mo, can maintain the etching rate, i.e., it is possible to suppress the variation in the etching rate between the etching rate at the time of initial use of the etching solution (Reference Example 1) and the etching rate at the time of reuse of the etching solution (Examples 1 and 2). Furthermore, when Example 3 and Comparative Example 1 were compared, even though the total amount of PEI in the etching solution when used for etching (0.2 mass%) was the same, Example 3, in which PEI was added in the addition step, showed a more suppressed increase in the etching rate than Comparative Example 1, in which no PEI was added in the addition step.

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

4. An etching method according to any one of claims 1 to 3, wherein the amount of component A in the etching solution used in the etching is 0.01 mass % or more and 10 mass % or less.

5. An etching method according to any one of claims 1 to 4, 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 relative to the total amount of the etching solution.

6. An etching method according to any one of claims 1 to 5, 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. The etching method according to any one of claims 1 to 6, wherein in the step of adding component A, the 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. An etching method according to any one of claims 1 to 7, 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. An etching method according to any one of claims 1 to 8, wherein the amount of nitric acid contained in the etching solution used in the etching is 0.1 mass % or more and 20 mass % or less.

10. An etching method according to any one of claims 1 to 9, wherein the etching solution further contains water, and 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 method according to any one of claims 1 to 10, wherein the etching solution further contains an organic acid, and the amount of organic acid contained in the etching solution used in the etching is 2% by mass or more and 60% by mass or less.

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 using the etching method according to any one of claims 1 to 12.

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