Etching solution composition

Abstract

To provide an etchant composition capable of reducing etching unevenness.SOLUTION: An etchant composition for etching an etched layer containing at least one metal contains an etching inhibitor, an acid containing at least nitric acid, and water, and has a pH of 1 or less, and the etching inhibitor is at least one nitrogen-containing compound selected from polyalkyleneimines and polymers containing structural units derived from diallylamine.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] In the manufacturing process of a semiconductor device, a 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 field has seen increasing integration, which has led to a demand for more complex and finer wiring. This has led to increasing demands for pattern processing techniques and etching solutions, and various etching methods have been proposed (Patent Documents 1 to 3).

[0003] For example, Patent Document 1 proposes a method of simultaneously etching a tungsten film and a titanium nitride film using an etching solution composition containing nitric acid and water. Patent Document 2 proposes a method of etching a tungsten layer using hydrogen peroxide and one of a strong acid and a strong base. Patent Document 3 proposes a method of simultaneously etching a tungsten film and a titanium nitride film using hydrogen peroxide, phosphoric acid, and an amine or amide polymer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-6715 [Patent Document 2] Japanese Patent Application Publication No. 2019-114791 [Patent Document 3] Korean Patent Publication 10-2014-0065771 Summary of the Invention [Problem to be solved by the invention]

[0005] In conventional etching methods, layers containing metals such as tungsten are often over-etched, resulting in uneven etching. In particular, in the manufacturing process of semiconductor wafers, there is a demand for an etching solution that is less likely to cause uneven etching, from the viewpoints of productivity and yield.

[0006] Therefore, in one aspect, the present disclosure provides an etching solution composition that can reduce etching unevenness and an etching method using the same. [Means for solving the problem]

[0007] In one aspect, the present disclosure relates to an etching solution composition for etching a layer to be etched that contains at least one type of metal, the etching solution composition comprising an etching inhibitor, an acid containing at least nitric acid, and water, and having a pH of 1 or less, wherein the etching inhibitor is at least one nitrogen-containing compound selected from the group consisting of polyalkyleneimine and a polymer containing a constitutional unit derived from diallylamine.

[0008] In one aspect, the present disclosure relates to an etching solution composition for etching a layer to be etched that contains at least one metal, the etching solution composition comprising an etching inhibitor, an acid containing phosphoric acid, acetic acid, and nitric acid, and water, and having a pH of 1 or less, wherein the etching inhibitor is a nitrogen-containing compound having an etching inhibition rate of 30% or more as determined under the following conditions: Here, the etching inhibition rate is a value obtained by subtracting the relative etching rate A of the etching rate of the etching solution composition from 100 when etching is performed at a predetermined temperature and for a predetermined time using a mixed acid aqueous solution containing phosphoric acid, acetic acid, nitric acid, and water, wherein the mass ratio of the blended amounts of phosphoric acid, acetic acid, and nitric acid is the same as the mass ratio of the blended amounts of phosphoric acid, acetic acid, and nitric acid in the etching solution composition and the total blended amount of phosphoric acid, acetic acid, and nitric acid is 86 mass%, where the etching rate is set to 100.

[0009] In one aspect, the present disclosure relates to an etching solution composition for etching a layer to be etched that contains at least one metal, the etching solution composition comprising an etching inhibitor, an acid containing at least nitric acid, and water, and having a pH of 1 or less, wherein the etching inhibitor is a nitrogen-containing compound that can adjust the zeta potential of the surface of the metal contained in the layer to be etched to more than 0 mV and not more than 50 mV.

[0010] In one aspect, the present disclosure relates to an etching method including a step of etching a layer to be etched that contains at least one metal using the etching solution composition of the present disclosure. [Effects of the Invention]

[0011] According to one aspect of the present disclosure, an etching solution composition capable of reducing etching unevenness can be provided. DETAILED DESCRIPTION OF THE INVENTION

[0012] In one aspect, the present disclosure is based on the finding that the etching rate can be slowed and etching unevenness can be reduced by using an etching solution containing at least an acid containing nitric acid, an etching inhibitor, and water.

[0013] In one aspect, the present disclosure relates to an etching solution composition for etching a layer to be etched that contains at least one metal, the etching solution composition comprising an etching inhibitor, an acid containing at least nitric acid, and water, and having a pH of 1 or less, wherein the etching inhibitor is at least one nitrogen-containing compound selected from the group consisting of polyalkyleneimine and polymers containing a constitutional unit derived from diallylamine (hereinafter also referred to as the "etching solution composition of the present disclosure"). The etching solution composition of the present disclosure can reduce etching unevenness.

[0014] Although the details of the mechanism by which the effects of the present disclosure are manifested are not clear, it is presumed as follows. By covering the surface of the layer to be etched without any gaps or by forming a thick protective film, the etching inhibition rate tends to be high. In the present disclosure, it is believed that the specific nitrogen-containing compound, which is an etching inhibitor, selectively adsorbs to the layer to be etched and gently etches the surface of the layer to be etched while protecting it, thereby reducing uneven etching. Furthermore, the zeta potential of the surface of the metal contained in the layer to be etched under acidic conditions is negative, and the nitrogen-containing compound serving as the etching inhibitor of the present disclosure is positively charged under acidic conditions, and therefore is easily selectively adsorbed to the layer to be etched. Therefore, in the present disclosure, the specific nitrogen-containing compound serving as the etching inhibitor gently etches the surface of the metal contained in the layer to be etched while protecting it, which is thought to reduce etching unevenness. It is presumed that conventional etching using hydrogen peroxide tends to oxidize the metal contained in the layer to be etched or to generate multiple types of oxides of the metal, which makes etching unevenness more likely to occur. Furthermore, it is presumed that nitrogen-containing compounds other than the etching inhibitors of the present disclosure (e.g., polyalkylene polyamines) are less likely to form a protective film on the surface of the metal contained in the layer to be etched, making etching unevenness more likely to occur. However, the present disclosure need not be construed as being limited to these mechanisms.

[0015] [Etching inhibitor] The etching inhibitor contained in the etching liquid composition of the present disclosure may be used alone or in combination of two or more types.

[0016] From the viewpoint of reducing etching unevenness, the etching inhibitor in the present disclosure preferably has an etching inhibition rate of 20% or more, more preferably 30% or more, even more preferably 40% or more, even more preferably 50% or more, even more preferably 60% or more, even more preferably 70% or more, even more preferably 80% or more, even more preferably 85% or more, even more preferably 90% or more, and even more preferably 94% or more. In the present disclosure, the etching inhibition rate refers to the rate of decrease in the etching rate when an etching inhibitor is used relative to the etching rate when no etching inhibitor is used. In one or more embodiments, the etching inhibition rate can be calculated by subtracting the relative etching rate A of the etching solution composition from 100, where A is the etching rate when etching is performed at a predetermined temperature and for a predetermined time using a mixed acid aqueous solution comprising phosphoric acid, acetic acid, nitric acid, and water, the mass ratio of the phosphoric acid, acetic acid, and nitric acid being the same as the mass ratio of the phosphoric acid, acetic acid, and nitric acid in the etching solution composition, and the total mass ratio of the phosphoric acid, acetic acid, and nitric acid is 86 mass%. The mass ratio of the amounts of each component in the mixed acid aqueous solution can be set as appropriate. In one or more embodiments, the etching inhibition rate can be measured by adjusting the operating conditions, such as temperature and time, to the etching conditions. The measurement conditions for the etching inhibition rate vary depending on the metal contained in the layer to be etched. In one or more embodiments, preferred ranges of temperature and time when measuring the etching inhibition rate include the preferred ranges of etching temperature and etching time in the etching step of the present disclosure described below. For example, the predetermined temperature and predetermined time for measuring the etching inhibition rate can be 90°C for 120 minutes when the metal plate used for measurement is a tungsten plate or a titanium plate, and 40°C for 10 minutes when the metal plate used for measurement is a molybdenum plate, a nickel plate, a cobalt plate, or a copper plate. The shape of the metal plate used for measurement can be, for example, a plate-like body with a length of 2 cm, a width of 2 cm, and a thickness of 0.1 mm. Specifically, the etching inhibition rate can be determined by the method described in the Examples.

[0017] In one or more embodiments, the etching inhibitor of the present disclosure is preferably a nitrogen-containing compound having an etching inhibition rate of 30% or more under the above conditions, from the viewpoint of reducing etching unevenness. Therefore, in one aspect, the present disclosure relates to an etching solution composition for etching a layer to be etched that contains at least one metal, the etching solution composition containing an etching inhibitor, an acid containing phosphoric acid, acetic acid, and nitric acid, and water, and having a pH of 1 or less, and the etching inhibitor is a nitrogen-containing compound that has an etching inhibition rate of 30% or more as determined under the above conditions.

[0018] In one or more embodiments, the etching inhibitor of the present disclosure includes at least one nitrogen-containing compound selected from polyalkyleneimines and polymers having constitutional units derived from diallylamine. Examples of the polyalkyleneimines include polyethyleneimine. Examples of the polymers having constitutional units derived from diallylamine include diallylamine / sulfur dioxide copolymers. Among these, in one or more embodiments, the etching inhibitor is preferably a polyalkyleneimine, more preferably a polyethyleneimine, from the viewpoint of reducing etching unevenness. Polyalkyleneimines such as polyethyleneimine are likely to form a protective film on the surface of the metal contained in the layer to be etched, and can suppress both the oxidation of the metal contained in the layer to be etched and the dissolution of the oxide of the metal, thereby suitably suppressing etching.

[0019] In one or more embodiments, the average molecular weight of the etching inhibitor is preferably 300 or more and 100,000 or less, from the viewpoint of further reducing etching unevenness. When the etching inhibitor is a polyalkyleneimine, the number average molecular weight of the etching inhibitor is preferably 300 or more, more preferably 600 or more, still more preferably 1,200 or more, from the viewpoint of further reducing etching unevenness in one or more embodiments, and preferably 100,000 or less, more preferably 5,000 or less, still more preferably 3,000 or less, from the viewpoint of viscosity. More specifically, the number average molecular weight of the etching inhibitor is preferably 300 or more and 100,000 or less, more preferably 600 or more and 5,000 or less, still more preferably 1,200 or more and 3,000 or less. Also, when the etching inhibitor is a polymer containing a structural unit derived from diallylamine, the weight average molecular weight of the etching inhibitor is preferably 2,000 or more, more preferably 3,000 or more, still more preferably 4,000 or more, from the viewpoint of further reducing etching unevenness 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 molecular weight of the etching inhibitor is preferably 2,000 or more and 50,000 or less, more preferably 3,000 or more and 10,000 or less, still more preferably 4,000 or more and 7,000 or less.

[0020] In the present disclosure, the average molecular weight can be measured by gel permeation chromatography (GPC) under the following conditions. <GPC conditions (polyalkyleneimine)> Sample solution: Adjusted to a concentration of 0.1 wt% Apparatus / detector: HLC-8320GPC (integrated GPC) manufactured by Tosoh Corporation Column: α-M + α-M (manufactured by Tosoh Corporation) Eluent: 0.15 mol / L Na2SO4, 1% CH3COOH / water Column temperature: 40°C Flow rate: 1.0 mL / min Sample solution injection volume: 100 μL Standard polymer: Pullulan with known molecular weight (Shodex P-5, P-50, P-200, P-800) <GPC Conditions (Polymer Containing Structural Units Derived from Diallylamine)> Sample solution: Adjusted to a concentration of 0.1 wt% Detector: HLC-8320GPC (Integrated GPC) manufactured by Tosoh Corporation Column: α-M + α-M (manufactured by Tosoh Corporation) Eluent: 0.15 mol / L Na2SO4, 1% CH3COOH / water Column temperature: 40 °C Flow rate: 1.0 mL / min Sample solution injection volume: 100 μL Standard polymer: Pullulan with known molecular weights (Shodex P-5, P-50, P-200, P-800)

[0021] In one or more embodiments, the etching inhibitor in the present disclosure is at least one nitrogen-containing compound selected from polyalkyleneimine and a polymer containing structural units derived from diallylamine, from the perspective of reducing etching unevenness, and is preferably a nitrogen-containing compound having an etching inhibition rate of 30% or more determined under the above conditions. Therefore, in one aspect, the present disclosure relates to an etching liquid composition for etching an etched layer containing at least one metal, the etching liquid composition comprising an etching inhibitor, an acid containing at least nitric acid, and water, having a pH of 1 or less, and the etching inhibitor is at least one nitrogen-containing compound selected from polyalkyleneimine and a polymer containing structural units derived from diallylamine, and is a nitrogen-containing compound having an etching inhibition rate of 30% or more determined under the above conditions.

[0022] In one or more embodiments, the etching inhibitor of the present disclosure is preferably a nitrogen-containing compound capable of adjusting the zeta potential of the surface of a metal contained in the layer to be etched to more than 0 mV and not more than 50 mV, from the viewpoint of reducing etching unevenness. From the viewpoint of reducing etching unevenness, the zeta potential of the surface of the metal is preferably more than 0 mV, more preferably 10 mV or more, and even more preferably 20 mV or more. The zeta potential of the surface of the metal may be 50 mV or less, 40 mV or less, or 35 mV or less. Therefore, in one aspect, the present disclosure relates to an etching solution composition for etching a layer to be etched that contains at least one metal, the etching solution composition containing an etching inhibitor, an acid containing at least nitric acid, and water, and having a pH of 1 or less, and the etching inhibitor is a nitrogen-containing compound that can adjust the zeta potential of the surface of the metal contained in the layer to be etched to more than 0 mV and 50 mV or less.

[0023] In the present disclosure, the zeta potential of the surface of the metal contained in the layer to be etched under acidic conditions is a negative value, and the nitrogen-containing compound serving as the etching inhibitor in the present disclosure is positively charged under acidic conditions, and therefore is easily selectively adsorbed to the layer to be etched. Therefore, when the layer to be etched is etched using the etching composition of the present disclosure, the zeta potential value of the surface of the metal contained in the layer to be etched changes to a positive value, which confirms that the etching inhibitor has been adsorbed to the metal surface, and the metal surface is slowly etched while being protected by the etching inhibitor, which is thought to reduce uneven etching.

[0024] The amount of etching inhibitor in the etching solution composition of the present disclosure is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.5% by mass or more, from the viewpoint of reducing etching unevenness. From the same viewpoint, it 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 etching inhibitor in the etching solution composition of the present disclosure is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.1% by mass or more and 5% by mass or less, and even more preferably 0.5% by mass or more and 3% by mass or less. When two or more etching inhibitors are used in combination, the amount of etching inhibitor is the total amount of the combined etching inhibitors.

[0025] [acid] The acid contained in the etching solution composition of the present disclosure is an acid containing at least nitric acid from the viewpoint of uniform etching of the layer to be etched. The acid may be used alone (nitric acid only) or in combination of two or more kinds.

[0026] In one or more embodiments, the acid in the present disclosure preferably further contains, in addition to nitric acid, at least one selected from phosphoric acid and an organic acid, from the viewpoint of reducing etching unevenness. Examples of organic acids include at least one selected from formic acid, acetic 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. In one or more embodiments, the acid in the present disclosure preferably further contains, in addition to nitric acid, at least one selected from phosphoric acid and acetic acid, from the viewpoint of reducing etching unevenness. For example, in one or more embodiments, the acid may be an acid containing phosphoric acid, acetic acid, and nitric acid, or a mixed acid consisting of phosphoric acid, acetic acid, and nitric acid.

[0027] When a mixed acid containing phosphoric acid, acetic acid, and nitric acid is used as the acid in the present disclosure, the amount of phosphoric acid in the mixed acid is preferably 50% by mass to 95% by mass, more preferably 55% by mass to 93% by mass, and even more preferably 60% by mass to 90% by mass, from the viewpoint of reducing etching unevenness. From the same viewpoint, the amount of acetic acid in the mixed acid is preferably 2% by mass to 80% by mass, more preferably 3% by mass to 70% by mass, and even more preferably 5% by mass to 60% by mass. From the same viewpoint, the amount of nitric acid in the mixed acid is preferably 0.5% by mass to 20% by mass, more preferably 1% by mass to 15% by mass, and even more preferably 1.5% by mass to 10% by mass. The mass ratio of phosphoric acid, acetic acid, and nitric acid (phosphoric acid / acetic acid / nitric acid) can be appropriately set, for example, to 88 / 8 / 4. In one or more embodiments of the present disclosure, the amount of each component in the mixed acid can be considered as the content of each component in the mixed acid.

[0028] When at least nitric acid is used as the acid in the present disclosure, the amount of nitric acid in the etching solution composition of the present disclosure is preferably 0.5% by mass or more and 20% by mass or less, more preferably 1% by mass or more and 10% by mass or less, and even more preferably 1.5% by mass or more and 5% by mass or less.

[0029] The amount of acid in the etching solution composition of the present disclosure 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 reducing etching unevenness. From the same viewpoint, it is preferably 98% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less. More specifically, the amount of acid in the etching solution composition of the present disclosure is preferably 70% by mass or more and 98% by mass or less, more preferably 75% by mass or more and 95% by mass or less, and even more preferably 80% by mass or more and 90% by mass or less. When two or more acids are used in combination, the amount of acid is the total amount of the acids.

[0030] [water] In one or more embodiments, the etching solution composition of the present disclosure 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.

[0031] From the viewpoint of reducing etching unevenness, the blending amount of water in the etching solution composition of the present disclosure is preferably 2% by mass or more, more preferably 5% by mass or more, and even more preferably 7% by mass or more, and 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 blending amount of water in the etching solution composition of the present disclosure is preferably 2% by mass or more and 30% by mass or less, more preferably 5% by mass or more and 25% by mass or less, and even more preferably 7% by mass or more and 20% by mass or less.

[0032] [Other ingredients] The etching solution composition of the present disclosure may further contain other components, such as chelating agents, surfactants, solubilizing agents, preservatives, rust inhibitors, disinfectants, antibacterial agents, and antioxidants, as long as the effects of the present disclosure are not impaired.

[0033] From the viewpoint of reducing etching unevenness, the etching solution composition of the present disclosure preferably does not contain hydrogen peroxide. Here, in one or more embodiments, "does not contain hydrogen peroxide" includes not containing hydrogen peroxide, not substantially containing hydrogen peroxide, or not containing an amount of hydrogen peroxide that would affect the etching result. The specific amount of hydrogen peroxide in the etching solution composition of the present disclosure is not particularly limited, but is preferably 3% by mass or less, more preferably 1% by mass or less, even more preferably 0.1% by mass or less, even more preferably 0.01% by mass or less, even more preferably 0.001% by mass or less, and even more preferably 0% by mass.

[0034] [Method of manufacturing the etching solution composition] In one aspect, the etching solution composition of the present disclosure is obtained by blending an etching inhibitor, an acid containing nitric acid, water, and, if desired, the optional components described above, by a known method. Thus, in one aspect, the present disclosure relates to a method for producing an etching solution composition (hereinafter also referred to as the "etching solution production method of the present disclosure"), which includes a step of blending at least an etching inhibitor, an acid containing nitric acid, and water. In the present disclosure, "blending at least an etching inhibitor, an acid containing nitric acid, and water" includes, in one or more embodiments, simultaneously or sequentially mixing the etching inhibitor, the acid containing nitric acid, 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-based liquid circulation agitator, a homomixer, a homogenizer, an ultrasonic disperser, or a wet ball mill. The preferred amount of each component in the method for producing an etching solution according to the present disclosure may be the same as the preferred amount of each component in the etching solution composition according to the present disclosure described above.

[0035] In the present disclosure, the term "amount of each component in the etching solution composition" refers, in one or more embodiments, to the amount of each component of the etching solution composition used in the etching step, i.e., at the time of starting use in the etching treatment (at the time of use). In one or more embodiments, the blending amount of each component in the etching solution composition of the present disclosure can be considered to be the content of each component in the etching solution composition of the present disclosure. However, if there is an effect of neutralization, the blending amount and the content may differ.

[0036] An embodiment of the etching solution composition of the present disclosure may be a so-called one-component type in which all components are supplied to the market in a pre-mixed state, or a so-called two-component type in which components are mixed at the time of use. One embodiment of a two-component etching solution composition is composed of a solution containing an etching inhibitor (first component) and an acid aqueous solution containing nitric acid (second component), and the first component and the second component are mixed at the time of use. The acid contained in the second component may be the entire amount of the acid used to prepare the etching solution composition, or may be a portion thereof. The first component may contain an acid. The first component and the second component may each contain the optional components described above as necessary.

[0037] From the viewpoint of reducing etching unevenness, the pH of the etching solution composition of the present disclosure is 1 or less, preferably 0 or less, more preferably less than 0, and even more preferably about -1. The pH of the etching solution composition of the present disclosure can be -5 or more, or -3 or more. In the present disclosure, the pH of the etching solution composition is a value at 25°C and can be measured using a pH meter, specifically, by the method described in the Examples.

[0038] The etching solution composition of the present disclosure may be stored and supplied in a concentrated state as long as its stability is not impaired. This is preferable in that production and transportation costs can be reduced. The concentrated solution can then be used in the etching process after being appropriately diluted with water or an aqueous acid solution, as needed. The dilution ratio can be, for example, 5 to 100 times.

[0039] [kit] In another aspect, the present disclosure relates to a kit for producing the etching liquid composition of the present disclosure (hereinafter also referred to as the "kit of the present disclosure").

[0040] An example of the kit of the present disclosure is a kit (two-component etching solution) that contains a solution (first liquid) containing an etching inhibitor and an acid aqueous solution (second liquid) containing at least nitric acid in a mutually immiscible state, and that is mixed at the time of use. After the first liquid and the second liquid are mixed, they may be diluted with water or an acid aqueous solution as needed. The first liquid or the second liquid may contain all or a portion of the water used to prepare the etching solution. The acid contained in the second liquid may be all or a portion of the acid used to prepare the etching solution. The first liquid may contain an acid. The first liquid and the second liquid may each contain the optional components described above as needed. The kit of the present disclosure can provide an etching solution that can reduce etching unevenness.

[0041] [Layer to be etched] In one or more embodiments, the layer to be etched using the etching solution composition of the present disclosure is a layer to be etched containing at least one metal. The metal is not particularly limited as long as the effects of the present invention are achieved, but examples include at least one metal selected from tungsten, tantalum, zirconium, hafnium, molybdenum, niobium, ruthenium, osmium, rhenium, rhodium, copper, nickel, cobalt, titanium, titanium nitride, alumina, aluminum, and iridium. Among these, in one or more embodiments, the etching solution composition of the present disclosure is preferably used to etch a layer to be etched containing at least one metal selected from the group consisting of tungsten, molybdenum, niobium, tantalum, and zirconium, and in one or more embodiments, is suitably used to etch a tungsten film or a molybdenum film. That is, in one or more embodiments, the layer to be etched is, for example, a tungsten film or a molybdenum film. In one or more embodiments, the etching solution composition of the present disclosure is preferably used for etching a layer to be etched that contains at least one metal selected from tungsten, molybdenum, copper, nickel, cobalt, and titanium, and in one or more embodiments, is suitably used for etching a tungsten film, a molybdenum film, a copper film, a nickel film, a cobalt film, or a titanium film. That is, in one or more embodiments, the layer to be etched includes a tungsten film, a molybdenum film, a copper film, a nickel film, a cobalt film, or a titanium film.

[0042] [Etching method] In one aspect, the present disclosure relates to an etching method (hereinafter also referred to as the "etching method of the present disclosure") that includes a step of etching a layer to be etched that contains at least one metal using an etching solution composition of the present disclosure (hereinafter also referred to as the "etching step of the present disclosure"). In one or more embodiments, use of the etching method of the present disclosure can reduce etching unevenness.

[0043] In the etching step of the present disclosure, examples of the etching method include immersion etching and single wafer etching.

[0044] In one or more embodiments, when the layer to be etched is a tungsten film, the temperature of the etching solution composition in the etching step of the present disclosure (etching temperature) is, from the viewpoint of reducing etching unevenness, preferably 0° C. or higher, more preferably 50° C. or higher, even more preferably 70° C. or higher, and preferably 150° C. or lower, more preferably 130° C. or lower, and even more preferably 110° C. or lower. More specifically, in one or more embodiments, when the layer to be etched is a tungsten film, the etching temperature is preferably 0° C. or higher and 150° C. or lower, more preferably 50° C. or higher and 130° C. or lower, and even more preferably 70° C. or higher and 110° C. or lower. In one or more embodiments, when the layer to be etched is a molybdenum film, the temperature of the etching solution composition in the etching step of the present disclosure (etching temperature) is, from the viewpoint of reducing etching unevenness, preferably 0° C. or higher, more preferably 15° C. or higher, even more preferably 25° 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 25° C. or higher and 50° C. or lower. In one or more embodiments, when the layer to be etched is a nickel film, the temperature of the etching solution composition in the etching step of the present disclosure (etching temperature) is, from the viewpoint of reducing etching unevenness, preferably 0° C. or higher, more preferably 15° C. or higher, even more preferably 30° C. or higher, and preferably 80° C. or lower, more preferably 65° C. or lower, and even more preferably 50° C. or lower. More specifically, in one or more embodiments, when the layer to be etched is a nickel film, the etching temperature is preferably 0° C. or higher and 80° C. or lower, more preferably 15° C. or higher and 65° C. or lower, and even more preferably 30° C. or higher and 50° C. or lower. In one or more embodiments, when the layer to be etched is a cobalt film, the temperature of the etching solution composition in the etching step of the present disclosure (etching temperature) is, from the viewpoint of reducing etching unevenness, preferably 0° C. or higher, more preferably 15° C. or higher, even more preferably 30° C. or higher, and preferably 80° C. or lower, more preferably 65° C. or lower, and even more preferably 50° C. or lower. More specifically, in one or more embodiments, when the layer to be etched is a cobalt film, the etching temperature is preferably 0° C. or higher and 80° C. or lower, more preferably 15° C. or higher and 65° C. or lower, and even more preferably 30° C. or higher and 50° C. or lower. In one or more embodiments, when the layer to be etched is a titanium film, the temperature of the etching solution composition in the etching step of the present disclosure (etching temperature) is, from the viewpoint of reducing etching unevenness, preferably 0° C. or higher, more preferably 50° C. or higher, even more preferably 70° C. or higher, and preferably 150° C. or lower, more preferably 130° C. or lower, and even more preferably 110° C. or lower. More specifically, in one or more embodiments, when the layer to be etched is a titanium film, the etching temperature is preferably 0° C. or higher and 150° C. or lower, more preferably 50° C. or higher and 130° C. or lower, and even more preferably 70° C. or higher and 110° C. or lower. In one or more embodiments, when the layer to be etched is a copper film, the temperature of the etching solution composition in the etching step of the present disclosure (etching temperature) is, from the viewpoint of reducing etching unevenness, preferably 0° C. or higher, more preferably 15° C. or higher, even more preferably 30° C. or higher, and preferably 80° C. or lower, more preferably 65° C. or lower, and even more preferably 50° C. or lower. More specifically, in one or more embodiments, when the layer to be etched is a copper film, the etching temperature is preferably 0° C. or higher and 80° C. or lower, more preferably 15° C. or higher and 65° C. or lower, and even more preferably 30° C. or higher and 50° C. or lower.

[0045] In the etching step of the present disclosure, the etching time can be set to, for example, 1 minute or more and 180 minutes or less.

[0046] In one or more embodiments, when the layer to be etched is a tungsten film, the etching rate in the etching step of the present disclosure is, from the viewpoint of improving productivity, preferably 0.0001 g / min or more, more preferably 0.0005 g / min or more, and even more preferably 0.001 g / min or more, and from the viewpoint of reducing etching unevenness, preferably 10 g / min or less, more preferably 1 g / min or less, and even more preferably 0.1 g / min or less. In one or more embodiments, when the layer to be etched is a molybdenum film, the etching rate in the etching step of the present disclosure is, from the viewpoint of improving productivity, preferably 0.01 g / min or more, more preferably 0.03 g / min or more, and even more preferably 0.05 g / min or more, and from the viewpoint of reducing etching unevenness, preferably 10 g / min or less, more preferably 3 g / min or less, and even more preferably 1 g / min or less. In one or more embodiments, when the layer to be etched is a nickel film, the etching rate in the etching step of the present disclosure is, from the viewpoint of improving productivity, preferably 0.001 g / min or more, more preferably 0.005 g / min or more, and even more preferably 0.01 g / min or more, and, from the viewpoint of reducing etching unevenness, is preferably 10 g / min or less, more preferably 1 g / min or less, and even more preferably 0.5 g / min or less. In one or more embodiments, when the layer to be etched is a cobalt film, the etching rate in the etching step of the present disclosure is, from the viewpoint of improving productivity, preferably 0.0001 g / min or more, more preferably 0.0005 g / min or more, and even more preferably 0.001 g / min or more, and from the viewpoint of reducing etching unevenness, preferably 10 g / min or less, more preferably 1 g / min or less, and even more preferably 0.1 g / min or less. In one or more embodiments, when the layer to be etched is a titanium film, the etching rate in the etching step of the present disclosure is preferably 0.00001 g / min or more, more preferably 0.0005 g / min or more, and even more preferably 0.001 g / min or more, from the viewpoint of improving productivity, and is preferably 10 g / min or less, more preferably 3 g / min or less, and even more preferably 1 g / min or less, from the viewpoint of reducing etching unevenness. In one or more embodiments, when the layer to be etched is a copper film, the etching rate in the etching step of the present disclosure is, from the viewpoint of improving productivity, preferably 0.0001 g / min or more, more preferably 0.0005 g / min or more, and even more preferably 0.001 g / min or more, and from the viewpoint of reducing etching unevenness, preferably 10 g / min or less, more preferably 1 g / min or less, and even more preferably 0.1 g / min or less.

[0047] In one or more embodiments, the etching liquid composition and etching method of the present disclosure can be used to etch metals in the manufacturing process of electronic devices, particularly semiconductor wafers. In one or more embodiments, the etching solution composition and the etching method of the present disclosure can be suitably used in the production of semiconductor wafers, thereby improving etching unevenness and increasing productivity and yield. In one or more embodiments, the etching solution composition and the etching method of the present disclosure can be used to etch electrodes in the manufacturing process of electronic devices, particularly semiconductor memories such as nonvolatile memories including NAND flash memories. In one or more embodiments, the etching solution composition and the etching method of the present disclosure can be suitably used for producing a pattern having a three-dimensional structure, thereby enabling the production of advanced devices such as high-capacity memories. The etching solution composition and the etching method of the present disclosure can be used, for example, in an etching method such as that disclosed in JP 2020-145412 A. [Example]

[0048] The present disclosure will be specifically described below using examples, but the present disclosure is not limited to these examples in any way.

[0049] 1. Preparation of Etching Solution Examples 1 to 9 The etching solutions (pH: -1) of Examples 1 to 9 were obtained by blending the etching inhibitor, mixed acid (phosphoric acid / acetic acid / nitric acid, mass ratio: 88 / 8 / 4) and water shown in Table 1. The mass ratio of the mixed acid was calculated by mass. (Comparative Example 1) The etching solution used in Comparative Example 1 was a mixed acid aqueous solution (pH: -1) containing phosphoric acid, acetic acid, nitric acid, and water in a mass ratio (phosphoric acid / acetic acid / nitric acid / water) of 76 / 7 / 3 / 14. (Comparative Example 2) The nitrogen-containing compound (arginine), mixed acid (phosphoric acid / acetic acid / nitric acid, mass ratio: 88 / 8 / 4) and water shown in Table 1 were mixed to obtain an etching solution (pH: -1) of Comparative Example 2. (Comparative Example 3) An etching inhibitor (polyethyleneimine), hydrogen peroxide, phosphoric acid, and water shown in Table 1 were blended to obtain an etching inhibitor of Comparative Example 3 (pH: -1). The amount of each component (mass %, active content) in the prepared etching solution is shown in Table 1. The amount of water in Table 1 also includes the amount of water contained in the acid aqueous solution, hydrogen peroxide solution, etc.

[0050] The following components were used to prepare the etching solution. (etch inhibitors or nitrogen-containing compounds) Polyethyleneimine [number average molecular weight 300, "Epomin SP-003" manufactured by Nippon Shokubai Co., Ltd.] Polyethyleneimine [number average molecular weight 600, "Epomin SP-006" manufactured by Nippon Shokubai Co., Ltd.] Polyethyleneimine [number average molecular weight 1,200, "Epomin SP-0012" manufactured by Nippon Shokubai Co., Ltd.] Polyethyleneimine [number average molecular weight 1,800, "Epomin SP-018" manufactured by Nippon Shokubai Co., Ltd.] Polyethyleneimine [number average molecular weight 10,000, "Epomin SP-200" manufactured by Nippon Shokubai Co., Ltd.] Polyethyleneimine [number average molecular weight 70,000, "Epomin P-1000" manufactured by Nippon Shokubai Co., Ltd.] Diallylamine acetate / sulfur dioxide copolymer [molar ratio 50 / 50, weight-average molecular weight 5,000, "PAS-92A" manufactured by Nittobo Medical Co., Ltd.] N-(2-hydroxyethyl)piperazine [molecular weight 130, Nippon Nyukazai Co., Ltd.] DL-arginine [molecular weight 174, Fujifilm Wako Pure Chemical Industries, Ltd.] (hydrogen peroxide) H2O2 [hydrogen peroxide, concentration 35% by mass, manufactured by ADEKA] (acid) Phosphoric acid [Rinkagaku Kogyo Co., Ltd., concentration 85%] Acetic acid [Fujifilm Wako Pure Chemical Corporation, concentration 100%] Nitric acid [Fujifilm Wako Pure Chemical Corporation, concentration 70%] (water) 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.]

[0051] 2.Measuring methods for each parameter [pH of etching solution] The pH value of the etching solution at 25° C. was measured using a pH meter (manufactured by DKK-Toa Corporation), and was the value measured one minute after the electrode of the pH meter was immersed in the etching solution.

[0052] 3-1. Evaluation of etching solution (layer to be etched: tungsten plate) [Evaluation of etching rate and etching inhibition rate of tungsten plate] A tungsten plate having a length of 2 cm, a width of 2 cm, and a thickness of 0.1 mm, the weight of which had been measured in advance, was immersed in the etching solution prepared for each composition (Examples 1 to 9 and Comparative Examples 1 to 3), and the tungsten plate was etched at 90°C for 120 minutes. After rinsing with water, the tungsten 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 of the tungsten plate was then calculated using the following formula: Etching rate (g / min) = Etching amount (g) / Etching time (min) The results of the etching rate of the tungsten plate are shown in Table 1 as relative values ​​(relative rates) with the etching rate of Comparative Example 1 taken as 100. In addition, the etching inhibition rate (%) is shown in Table 1, calculated by subtracting the relative rate of each example from 100, with the etching rate of Comparative Example 1 taken as 100. The etching rate and etching inhibition rate can be evaluated using a molybdenum plate having a length of 2 cm, a width of 2 cm, and a thickness of 0.1 mm instead of a tungsten plate having a length of 2 cm, a width of 2 cm, and a thickness of 0.1 mm, or the wafer shown in FIG. 1 of JP-A-2020-145412.

[0053] [Evaluation of etching irregularities on tungsten plates (surface accuracy)] A tungsten plate with a length of 2 cm, a width of 2 cm, and a thickness of 0.1 mm, the weight of which had been measured in advance, was immersed in the etching solution prepared for each composition (Examples 1 to 9 and Comparative Examples 1 to 3), and the tungsten plate was etched at 90°C for 120 minutes. After rinsing with water, the surface of the tungsten plate was again observed using a Keyence VK-9710 shape measuring laser microscope (lens magnification: 150x), and photographs were analyzed using the same instrument's surface roughness mode. Surface precision (etching unevenness) was then determined. The surface precision of the tungsten plate was evaluated based on the following evaluation criteria, and the results are shown in Table 1. Surface precision (%) = Surface roughness after etching / Surface roughness before etching x 100 <Evaluation criteria> 5: Surface accuracy less than 120% 4: Surface accuracy 120% or more but less than 200% 3: Surface accuracy 200% or more but less than 300% 2: Surface accuracy 300% or more but less than 500% 1: Surface accuracy 500% or more but less than 700% 0: Surface accuracy 700% or more The evaluation of the etching unevenness can be performed using a molybdenum plate having a length of 2 cm, a width of 2 cm, and a thickness of 0.1 mm instead of a tungsten plate having a length of 2 cm, a width of 2 cm, and a thickness of 0.1 mm, or the wafer shown in FIG. 1 of JP-A-2020-145412.

[0054] [Zeta potential] A tungsten standard solution was added at 100 ppm to the etching solutions prepared to each composition (Examples 1 to 9 and Comparative Examples 1 to 3), and samples for zeta potential measurement were prepared. A precision balance was used to measure the weight. This prepared solution was placed in a capillary cell DTS1070, and the zeta potential was measured using a Malvern Zetasizer Nano ZS under the following conditions. <Measurement conditions> Tungsten: Refractive index: 2.200 Absorption index: 0.390 Dispersion medium: viscosity: 39cP, refractive index: 1.426 Temperature: 25℃

[0055] [Table 1]

[0056] As shown in Table 1, Examples 1 to 9, which contained an etching inhibitor and a mixed acid (an acid containing nitric acid), all had a slower etching rate for the tungsten plate and reduced etching unevenness compared to Comparative Examples 1 and 2, which did not contain an etching inhibitor, and Comparative Example 3, which contained an acid not containing nitric acid.

[0057] Furthermore, the etching solutions of Examples 1, 3 to 4 and Comparative Examples 1 to 3 were further evaluated as follows.

[0058] 3-2. Evaluation of etching solution (etched layer: nickel plate) [Evaluation of etching rate and etching inhibition rate of nickel plate] The nickel plate was etched in the same manner as the tungsten etching method described above, except that a nickel plate measuring 2 cm in length, 2 cm in width, and 0.1 mm in thickness was used instead of the tungsten plate, and the etching conditions were changed to an etching temperature of 40°C and an etching time of 10 minutes, and the etching rate of the nickel plate was measured. The results of the etching rate of the nickel plate are shown in Table 2. In addition, the etching rate of Comparative Example 1 was taken as 100, and the relative rate of each Example was subtracted from 100 to obtain the etching inhibition rate (%), which is shown in Table 2.

[0059] [Evaluation of uneven etching of nickel plate (surface accuracy)] A nickel plate with a length of 2 cm, a width of 2 cm, and a thickness of 0.1 mm, the weight of which had been measured in advance, was immersed in the prepared etching solution (Examples 1, 3-4, and Comparative Examples 1-3), and the nickel plate was etched at 40°C for 10 minutes. After rinsing with water, the surface of the nickel plate was again observed using a Keyence VK-9710 shape measuring laser microscope (lens magnification: 150x), and photographs were analyzed using the same instrument's surface roughness mode. The surface precision (etching unevenness) was then determined. The surface precision of the nickel plate was evaluated based on the same evaluation criteria as for the surface precision evaluation of tungsten described above, and the results are shown in Table 2.

[0060] [Table 2]

[0061] As shown in Table 2, Examples 1, 3 and 4, which contained an etching inhibitor and a mixed acid (an acid containing nitric acid), had reduced etching unevenness compared to Comparative Examples 1 and 2, which did not contain an etching inhibitor, and Comparative Example 3, which contained an acid not containing nitric acid.

[0062] 3-3. Evaluation of etching solution (layer to be etched: cobalt plate) [Evaluation of etching rate and etching inhibition rate of cobalt plate] The cobalt plate was etched in the same manner as the tungsten etching method described above, except that a cobalt plate measuring 2 cm in length, 2 cm in width, and 0.1 mm in thickness was used instead of the tungsten plate, and the etching conditions were changed to an etching temperature of 40°C and an etching time of 10 minutes, and the etching rate of the cobalt plate was measured. The results of the etching rate of the cobalt plate are shown in Table 3. In addition, the etching rate of Comparative Example 1 was taken as 100, and the relative rate of each Example was subtracted from 100 to obtain the etching inhibition rate (%), which is shown in Table 3.

[0063] [Evaluation of uneven etching of cobalt plate (surface accuracy)] A pre-weighed cobalt plate measuring 2 cm in length, 2 cm in width, and 0.1 mm in thickness was immersed in the prepared etching solution (Examples 1, 3-4, and Comparative Examples 1-3), and the cobalt plate was etched at 40°C for 10 minutes. After rinsing with water, the surface of the cobalt plate was again observed using a Keyence VK-9710 shape measurement laser microscope (lens magnification: 150x), and photographs were analyzed using the same microscope's surface roughness mode. Surface precision (etching unevenness) was then determined. The surface precision of the cobalt plate was evaluated based on the same evaluation criteria as for the surface precision evaluation of tungsten described above, and the results are shown in Table 3.

[0064] [Table 3]

[0065] As shown in Table 3, Examples 1, 3 and 4, which contained an etching inhibitor and a mixed acid (an acid containing nitric acid), had reduced etching unevenness compared to Comparative Examples 1 and 2, which did not contain an etching inhibitor, and Comparative Example 3, which contained an acid not containing nitric acid.

[0066] 3-4. Evaluation of etching solution (etched layer: titanium plate) [Evaluation of etching rate and etching inhibition rate of titanium plate] The etching rate of the titanium plate was measured in the same manner as the tungsten etching method described above, except that a titanium plate measuring 2 cm in length, 2 cm in width, and 0.1 mm in thickness was used instead of the tungsten plate. The results of the etching rate of the titanium plate are shown in Table 4. The etching rate of Comparative Example 1 was taken as 100, and the relative rate of each Example was subtracted from 100 to obtain the etching inhibition rate (%), which is shown in Table 4.

[0067] [Evaluation of etching irregularities on titanium plates (surface accuracy)] A titanium plate measuring 2 cm in length, 2 cm in width, and 0.1 mm in thickness, the weight of which had been measured in advance, was immersed in the prepared etching solution (Examples 1, 3-4, and Comparative Examples 1-3), and the titanium plate was etched at 90°C for 120 minutes. After rinsing with water, the surface of the cobalt plate was again observed using a Keyence VK-9710 shape measurement laser microscope (lens magnification: 150x), and photographs were analyzed using the same instrument's surface roughness mode. Surface precision (etching unevenness) was then determined. The surface precision of the titanium plate was evaluated based on the same evaluation criteria as for the surface precision evaluation of tungsten described above, and the results are shown in Table 4.

[0068] [Table 4]

[0069] As shown in Table 4, Examples 1 and 3-4, which contain an etching inhibitor and a mixed acid (an acid containing nitric acid), showed reduced etching unevenness compared to Comparative Examples 1-2, which do not contain an etching inhibitor, and Comparative Example 3, which contains an acid not containing nitric acid.

[0070] 3-5. Evaluation of etching solution (layer to be etched: copper plate) [Evaluation of etching rate and etching inhibition rate of copper plate] The copper plate was etched in the same manner as the tungsten etching method described above, except that a copper plate measuring 2 cm in length, 2 cm in width, and 0.1 mm in thickness was used instead of the tungsten plate, and the etching conditions were changed to an etching temperature of 40°C and an etching time of 10 minutes, and the etching rate of the copper plate was measured. The results of the copper plate etching rate are shown in Table 5. In addition, the etching rate of Comparative Example 1 was taken as 100, and the relative rate of each Example was subtracted from 100 to obtain the etching inhibition rate (%), which is shown in Table 5.

[0071] [Evaluation of uneven etching on copper plate (surface accuracy)] A copper plate with a length of 2 cm, a width of 2 cm, and a thickness of 0.1 mm, the weight of which had been measured in advance, was immersed in the prepared etching solution (Examples 1, 3-4, and Comparative Examples 1-3), and the copper plate was etched at 40°C for 10 minutes. After rinsing with water, the surface of the copper plate was again observed using a Keyence VK-9710 shape measuring laser microscope (lens magnification: 150x), and photographs were analyzed using the same instrument's surface roughness mode. The surface precision (etching unevenness) was then determined. The surface precision of the copper plate was evaluated based on the same evaluation criteria as for the surface precision evaluation of tungsten described above, and the results are shown in Table 5.

[0072] [Table 5]

[0073] As shown in Table 5, Examples 1, 3 and 4, which contained an etching inhibitor and a mixed acid (an acid containing nitric acid), had reduced etching unevenness compared to Comparative Examples 1 and 2, which did not contain an etching inhibitor, and Comparative Example 3, which contained an acid not containing nitric acid. [Industrial Applicability]

[0074] The etching solution composition of the present disclosure can reduce etching unevenness and is useful in a method for manufacturing a large-capacity semiconductor memory.

Claims

1. An etching method comprising a step of etching a layer to be etched, the layer including a molybdenum film, using an etching solution composition, the etching solution composition contains an etching inhibitor, an acid containing at least nitric acid, and water, and has a pH of 1 or less; The etching method, wherein the etching inhibitor is at least one nitrogen-containing compound selected from the group consisting of polyalkyleneimines having an average molecular weight of 1,200 or more and 3,000 or less, and polymers containing constitutional units derived from diallylamine.

2. 2. The etching method of claim 1, wherein the etching inhibitor is polyethyleneimine.

3. 3. The etching method according to claim 1, wherein the acid further contains at least one selected from phosphoric acid and acetic acid in addition to nitric acid.

4. An etching method described in any one of claims 1 to 3, wherein the acid containing at least nitric acid is a mixed acid consisting of phosphoric acid, acetic acid and nitric acid.

5. An etching method as described in claim 4, wherein the amount of phosphoric acid in the mixed acid is 50 mass% or more and 95 mass% or less.

6. An etching method as described in claim 4 or 5, wherein the amount of acetic acid in the mixed acid is 2 mass% or more and 80 mass% or less.

7. An etching method described in any one of claims 1 to 6, wherein the amount of the etching inhibitor is 0.5 mass% or more and 3 mass% or less.

8. An etching method described in any one of claims 1 to 7, wherein the amount of acid in the etching solution composition is 70 mass% or more and 98 mass% or less.

9. The etching method according to claim 1 , wherein the etching solution composition does not contain hydrogen peroxide.

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