Etching solution composition

Abstract

In one embodiment, an etching solution composition that can reduce etching unevenness is provided. [Solution] In one aspect, the present disclosure relates to an etching solution composition for etching a layer to be etched containing at least one metal, wherein the etching solution composition comprises 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 polymers containing polyalkylene imines and diallylamine-derived structural units.

Description

Technical Field

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

Background Art

[0002] In the manufacturing process of semiconductor devices, for example, a step of etching an etched layer containing at least one metal such as tungsten, tantalum, zirconium, hafnium, molybdenum, niobium, ruthenium, osmium, rhenium, rhodium, copper, nickel, cobalt, titanium, titanium nitride, alumina, aluminum, and iridium is performed to process it into a predetermined pattern shape. In recent years, in the semiconductor field, high integration has been progressing, and there is a demand for more complex and finer wiring. The requirements for pattern processing technology and etching solutions are also increasing, and various etching methods have been proposed (Patent Documents 1 to 3).

[0003] For example, Patent Document 1 proposes a method of collectively 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 or a strong base. Patent Document 3 proposes a method of collectively etching a tungsten film and a titanium nitride film using hydrogen peroxide, phosphoric acid, and an amine or an amide polymer.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

[0005] Conventional etching methods sometimes resulted in uneven etching due to excessive etching of the layer to be etched, which contained metals such as tungsten. In particular, in the semiconductor wafer manufacturing process, there is a need for etching solutions that are less prone to etching unevenness, from the viewpoint of productivity and yield.

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

[0007] This disclosure relates, in one aspect, to an etching solution composition for etching a layer to be etched containing at least one metal, wherein the etching solution composition comprises 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 polymers containing polyalkylene imines and diallylamine-derived structural units.

[0008] This disclosure relates, in one embodiment, to an etching solution composition for etching a layer to be etched containing at least one metal, wherein the etching solution composition contains an etching inhibitor, an acid including phosphoric acid, acetic acid, and nitric acid, and water, has a pH of 1 or less, and the etching inhibitor is a nitrogen-containing compound having an etching inhibition rate of 30% or more as determined by the following conditions. Here, the etching inhibition rate is defined as the relative etching rate A of the etching solution composition, which is set to 100 when etching is performed at a predetermined temperature and time using a mixed acid aqueous solution consisting of phosphoric acid, acetic acid, nitric acid, and water, wherein the mass ratio of the amounts of phosphoric acid, acetic acid, and nitric acid is the same as the mass ratio of the amounts of phosphoric acid, acetic acid, and nitric acid in the etching solution composition, and the total amount of phosphoric acid, acetic acid, and nitric acid is 86% by mass, and the etching rate is set to 100.

[0009] This disclosure relates, in one embodiment, to an etching solution composition for etching a layer to be etched containing at least one metal, wherein the etching solution composition contains an etching inhibitor, an acid containing at least nitric acid, and water, has a pH of 1 or less, and the etching inhibitor is a nitrogen-containing compound that can raise the zeta potential of the surface of the metal contained in the layer to be etched to more than 0 mV and less than or equal to 50 mV.

[0010] This disclosure relates, in one embodiment, to an etching method comprising the step of etching a layer to be etched, which contains at least one metal, using the etching solution composition of this disclosure. [Effects of the Invention]

[0011] According to this disclosure, in one embodiment, an etching solution composition that can reduce etching unevenness can be provided. [Modes for carrying out the invention]

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

[0013] This disclosure relates, in one embodiment, to an etching solution composition for etching a layer to be etched containing at least one metal, wherein the etching solution composition comprises 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 polymers containing polyalkylene imines and diallylamine-derived structural units (hereinafter also referred to as "the etching solution composition of this disclosure"). The etching solution composition of this disclosure can reduce etching unevenness.

[0014] Although the detailed mechanism of how the effects of this disclosure are realized is not clear, it is presumed to be as follows. By completely covering the surface of the layer to be etched or by forming a thick protective film, the etching suppression rate tends to increase. In this disclosure, it is believed that a specific nitrogen-containing compound, which acts as an etching inhibitor, selectively adsorbs onto the layer to be etched, and gradually etches the layer while protecting its surface, thereby reducing etching unevenness. Furthermore, under acidic conditions, the zeta potential of the metal surface in the layer to be etched is negative, and the nitrogen-containing compound, which is the etching inhibitor in this disclosure, carries a positive charge under acidic conditions, and therefore is easily selectively adsorbed onto the layer to be etched. Accordingly, in this disclosure, it is believed that etching unevenness can be reduced because the specific nitrogen-containing compound, which is the etching inhibitor, slowly etches the metal surface in the layer to be etched while protecting it. Furthermore, it is presumed that conventional etching using hydrogen peroxide tends to result in uneven etching because multiple types of oxidation states and oxides of the metal contained in the etched layer are easily formed. In addition, it is presumed that nitrogen-containing compounds other than the etching inhibitors of this disclosure (e.g., polyalkylene polyamines) do not easily form a protective film on the surface of the metal contained in the etched layer, which also tends to result in uneven etching. However, this disclosure does not have to be construed as being limited to these mechanisms.

[0015] [Etching inhibitor] The etching inhibitor contained in the etching solution composition of this 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 this 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 this disclosure, etching inhibition rate refers to the rate of reduction in etching rate when an etching inhibitor is used compared to the etching rate when no etching inhibitor is used. In one or more embodiments, the etching inhibition rate can be defined as the relative etching rate A of the etching solution composition, where the etching rate when etching is performed at a predetermined temperature and time using a mixed acid aqueous solution consisting of phosphoric acid, acetic acid, nitric acid, and water, wherein the mass ratio of the amounts of phosphoric acid, acetic acid, and nitric acid is the same as the mass ratio of the amounts of phosphoric acid, acetic acid, and nitric acid in the etching solution composition, and the total amount of phosphoric acid, acetic acid, and nitric acid is 86% by mass, is set to 100, and the relative etching rate A of the etching solution composition is subtracted from 100. 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 implementation conditions such as temperature and time to match the etching conditions. The measurement conditions for the etching inhibition rate vary depending on the metal contained in the layer to be etched, and preferred ranges for temperature and time when measuring the etching inhibition rate include, in one or more embodiments, preferred ranges for etching temperature and etching time in the etching process of this disclosure described later. For example, the predetermined temperature and time for measuring the etching inhibition rate can be 90°C for 120 minutes if the metal plate used for measurement is a tungsten plate or a titanium plate, and 40°C for 10 minutes if the metal plate is a molybdenum plate, nickel plate, cobalt plate, or copper plate. The shape of the metal plate used for measurement can be, for example, a plate-like body with dimensions of 2 cm in length, 2 cm in width, and 0.1 mm in thickness. The etching inhibition rate can be specifically determined by the method described in the examples.

[0017] In one or more embodiments of this disclosure, the etching inhibitor is preferably a nitrogen-containing compound that has 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 liquid composition for etching an etching layer containing at least one metal, the etching liquid composition containing an etching inhibitor, an acid containing phosphoric acid, acetic acid, and nitric acid, and water, having a pH of 1 or less, and the etching inhibitor being a nitrogen-containing compound having an etching inhibition rate of 30% or more determined under the above conditions.

[0018] As the etching inhibitor in the present disclosure, in one or more embodiments, at least one nitrogen-containing compound selected from polyalkyleneimine and a polymer having a structural unit derived from diallylamine can be mentioned. Examples of the polyalkyleneimine include polyethyleneimine and the like. Examples of the polymer containing a structural unit derived from diallylamine include diallylamine / sulfur dioxide copolymer and the like. Among these, as the etching inhibitor, in one or more embodiments, from the viewpoint of reducing etching unevenness, polyalkyleneimine is preferable, and polyethyleneimine is more preferable. Polyalkyleneimines such as polyethyleneimine are likely to form a protective film on the surface of the metal contained in the etching layer, can suppress both the oxidation of the metal contained in the etching layer and the dissolution of the oxide of the metal, and can preferably suppress etching.

[0019] In one or more embodiments, from the viewpoint of further reducing etching unevenness, the average molecular weight of the etching inhibitor is preferably 300 or more and preferably 100,000 or less. 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 from 300 to 100,000, more preferably from 600 to 5,000, still more preferably from 1,200 to 3,000. 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 from 2,000 to 50,000, more preferably from 3,000 to 10,000, still more preferably from 4,000 to 7,000.

[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 weights (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 non-uniformity, and the nitrogen-containing compound preferably has an etching inhibition rate of 30% or more as 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, wherein the etching liquid composition includes an etching inhibitor, an acid containing at least nitric acid, and water, has 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 as determined under the above conditions.

[0022] In one or more embodiments, the etching inhibitor in this disclosure is preferably a nitrogen-containing compound that can raise the zeta potential of the surface of the metal contained in the etched layer to more than 0 mV and 50 mV or less, from the viewpoint of reducing etching unevenness. From the viewpoint of reducing etching unevenness, the zeta potential of the metal surface is preferably greater than 0 mV, more preferably 10 mV or more, and even more preferably 20 mV or more. The zeta potential of the metal surface may be 50 mV or less, 40 mV or less, or 35 mV or less. Accordingly, in one aspect, the present disclosure relates to an etching solution composition for etching a layer to be etched containing at least one metal, wherein the etching solution composition contains an etching inhibitor, an acid containing at least nitric acid, and water, has a pH of 1 or less, and the etching inhibitor is a nitrogen-containing compound that can raise the zeta potential of the surface of the metal contained in the layer to be etched from more than 0 mV to 50 mV or less.

[0023] In this disclosure, the zeta potential of the metal surface in the layer to be etched is negative under acidic conditions, and the nitrogen-containing compound, which is the etching inhibitor in this disclosure, is positively charged under acidic conditions and therefore readily adsorbs selectively onto the layer to be etched. Consequently, when the layer to be etched is etched using the etching composition of this disclosure, the zeta potential of the metal surface in the layer to be etched changes to a positive value, confirming that the etching inhibitor has adsorbed onto the metal surface. Since the metal surface is protected by the etching inhibitor and etched slowly, it is believed that etching unevenness can be reduced.

[0024] From the viewpoint of reducing etching unevenness, the amount of etching inhibitor in the etching solution composition of this 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. Similarly, 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 this 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 there is a combination of two or more etching inhibitors, the amount of etching inhibitors is the total amount of those inhibitors.

[0025] [acid] The acid contained in the etching solution composition of this 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 two or more acids may be used in combination.

[0026] In one or more embodiments, the acid in this disclosure preferably further comprises, in addition to nitric acid, at least one selected from phosphoric acid and organic acids, 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 this disclosure preferably further comprises, 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 include an acid containing phosphoric acid, acetic acid, and nitric acid, and in one or more embodiments, a mixed acid consisting of phosphoric acid, acetic acid, and nitric acid.

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

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

[0029] From the viewpoint of reducing etching unevenness, the amount of acid in the etching solution composition of this disclosure is preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more. Similarly, 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 this 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. If there is a combination of two or more acids, the amount of acid is the total amount of those acids.

[0030] [water] The etching solution compositions of this disclosure include water in one or more embodiments. Examples of water contained in the etching solution of this disclosure include distilled water, deionized water, pure water, and ultrapure water.

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

[0032] [Other ingredients] The etching solution composition of this disclosure may further contain other components, to the extent that the effects of this disclosure are not impaired. Examples of other components include chelating agents, surfactants, solubilizers, preservatives, rust inhibitors, bactericides, antimicrobial agents, and antioxidants.

[0033] The etching solution compositions of this disclosure are preferably hydrogen peroxide-free from the viewpoint of reducing etching unevenness. Here, "hydrogen peroxide-free" includes, in one or more embodiments, the absence of hydrogen peroxide, substantially the absence of hydrogen peroxide, or the absence of hydrogen peroxide in an amount that affects the etching result. The specific amount of hydrogen peroxide blended in the etching solution compositions of this 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 for producing etching solution composition] In one embodiment, the etching solution composition of this disclosure is obtained by compounding an etching inhibitor, an acid containing nitric acid, water, and optionally the above-mentioned optional components in a known manner. Accordingly, in one embodiment, this disclosure relates to a method for producing an etching solution composition (hereinafter also referred to as "the etching solution production method of this disclosure") which includes at least the step of compounding an etching inhibitor, an acid containing nitric acid, and water. In this disclosure, "combining at least an etching inhibitor, an acid containing nitric acid, and water" means, in one or more embodiments, simultaneously or sequentially mixing an etching inhibitor, an acid containing nitric acid, water, and any of the above-mentioned optional components as needed. The order of mixing is not particularly limited. The compounding can be carried out using a mixer such as a propeller-type stirrer, liquid circulation stirring with a pump, a homomixer, a homogenizer, an ultrasonic disperser, and a wet ball mill. In the etching solution manufacturing method of this disclosure, the preferred blending amounts of each component can be the same as the preferred blending amounts of each component of the etching solution composition of this disclosure described above.

[0035] In this disclosure, "amount of each component in the etching solution composition" means, in one or more embodiments, the amount of each component of the etching solution composition used in the etching process, i.e., at the time of use when the etching process begins (at the time of use). The amounts of each component in the etching solution composition of this disclosure can be considered as the content of each component in the etching solution composition of this disclosure in one or more embodiments. However, the amounts of each component and the content may differ when neutralization is involved.

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

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

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

[0039] [kit] In other embodiments, this disclosure relates to a kit for manufacturing the etching solution composition of this disclosure (hereinafter also referred to as the "Kit of this Disclosure").

[0040] Examples of the kits of this disclosure include a two-component etching solution containing, for example, a solution containing an etching inhibitor (first solution) and an aqueous acid solution containing at least nitric acid (second solution), which are mixed separately and mixed at the time of use. After the first and second solutions are mixed, they may be diluted with water or an aqueous acid solution as needed. The first or second solution may contain all or part of the water used to prepare the etching solution. The acid contained in the second solution may be all or part of the acid used to prepare the etching solution. The first solution may contain an acid. The first and second solutions may each contain the above-mentioned optional components as needed. According to the kits of this disclosure, an etching solution capable of reducing etching unevenness can be obtained.

[0041] [Etched layer] In one or more embodiments, the layer to be etched using the etching solution composition of this disclosure is an etchable layer containing at least one metal. Here, the metal is not particularly limited as long as the effects of 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, the etching solution composition of this disclosure is preferably used in one or more embodiments to etch a layer to be etched containing at least one metal selected from the group of tungsten, molybdenum, niobium, tantalum, and zirconium, and is suitably used in one or more embodiments to etch a tungsten film or a molybdenum film. That is, in one or more embodiments, the layer to be etched is a tungsten film or a molybdenum film. The etching solution compositions of this disclosure are preferably used in one or more embodiments to etch a layer to be etched containing at least one metal selected from tungsten, molybdenum, copper, nickel, cobalt, and titanium, and are suitably used in one or more embodiments to etch tungsten films, molybdenum films, copper films, nickel films, cobalt films, or titanium films. That is, examples of the layer to be etched in one or more embodiments include tungsten films, molybdenum films, copper films, nickel films, cobalt films, or titanium films.

[0042] [Etching method] This disclosure relates, in one embodiment, to an etching method (hereinafter also referred to as "the etching method of this disclosure") which includes a step of etching a layer to be etched containing at least one metal using the etching solution composition of this disclosure (hereinafter also referred to as "the etching step of this disclosure"). By using the etching method of this disclosure, etching unevenness can be reduced in one or more embodiments.

[0043] In the etching process of this disclosure, examples of etching methods 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 process of this disclosure (etching temperature) is preferably 0°C or higher, more preferably 50°C or higher, even more preferably 70°C or higher, and preferably 150°C or lower, more preferably 130°C or lower, and even more preferably 110°C or lower, from the viewpoint of reducing etching unevenness. More specifically, in one or more embodiments, when the layer to be etched is a tungsten film, the etching temperature is preferably 0°C or higher and 150°C or lower, more preferably 50°C or higher and 130°C or lower, and even more preferably 70°C or higher and 110°C or lower. In one or more embodiments, when the layer to be etched is a molybdenum film, the temperature of the etching solution composition in the etching process of the present disclosure (etching temperature) is preferably 0°C or higher, more preferably 15°C or higher, even more preferably 25°C or higher, and preferably 80°C or lower, more preferably 65°C or lower, and even more preferably 50°C or lower, from the viewpoint of reducing etching unevenness. More specifically, in one or more embodiments, when the layer to be etched is a molybdenum film, the etching temperature is preferably 0°C or higher and 80°C or lower, more preferably 15°C or higher and 65°C or lower, and even more preferably 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 process of the present disclosure (etching temperature) is preferably 0°C or higher, more preferably 15°C or higher, even more preferably 30°C or higher, and preferably 80°C or lower, more preferably 65°C or lower, and even more preferably 50°C or lower, from the viewpoint of reducing etching unevenness. More specifically, in one or more embodiments, when the layer to be etched is a nickel film, the etching temperature is preferably 0°C or higher and 80°C or lower, more preferably 15°C or higher and 65°C or lower, and even more preferably 30°C or higher and 50°C or lower. In one or more embodiments, when the layer to be etched is a cobalt film, the temperature of the etching solution composition in the etching process of the present disclosure (etching temperature) is preferably 0°C or higher, more preferably 15°C or higher, even more preferably 30°C or higher, and preferably 80°C or lower, more preferably 65°C or lower, and even more preferably 50°C or lower, from the viewpoint of reducing etching unevenness. More specifically, in one or more embodiments, when the layer to be etched is a cobalt film, the etching temperature is preferably 0°C or higher and 80°C or lower, more preferably 15°C or higher and 65°C or lower, and even more preferably 30°C or higher and 50°C or lower. In one or more embodiments, when the layer to be etched is a titanium film, the temperature of the etching solution composition in the etching process of this disclosure (etching temperature) is preferably 0°C or higher, more preferably 50°C or higher, even more preferably 70°C or higher, and preferably 150°C or lower, more preferably 130°C or lower, and even more preferably 110°C or lower, from the viewpoint of reducing etching unevenness. More specifically, in one or more embodiments, when the layer to be etched is a titanium film, the etching temperature is preferably 0°C or higher and 150°C or lower, more preferably 50°C or higher and 130°C or lower, and even more preferably 70°C or higher and 110°C or lower. In one or more embodiments, when the layer to be etched is a copper film, the temperature of the etching solution composition in the etching process of the present disclosure (etching temperature) is preferably 0°C or higher, more preferably 15°C or higher, even more preferably 30°C or higher, and preferably 80°C or lower, more preferably 65°C or lower, and even more preferably 50°C or lower, from the viewpoint of reducing etching unevenness. More specifically, in one or more embodiments, when the layer to be etched is a copper film, the etching temperature is preferably 0°C or higher and 80°C or lower, more preferably 15°C or higher and 65°C or lower, and even more preferably 30°C or higher and 50°C or lower.

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

[0046] In one or more embodiments, when the layer to be etched is a tungsten film, the etching rate in the etching process of this disclosure is 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, from the viewpoint of improving productivity, and preferably 10 g / min or less, more preferably 1 g / min or less, and even more preferably 0.1 g / min or less, from the viewpoint of reducing etching unevenness. In one or more embodiments, when the layer to be etched is a molybdenum film, the etching rate in the etching process of this disclosure is 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, from the viewpoint of improving productivity, and 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 nickel film, the etching rate in the etching process of this disclosure is 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, from the viewpoint of improving productivity, and preferably 10 g / min or less, more preferably 1 g / min or less, and even more preferably 0.5 g / min or less, from the viewpoint of reducing etching unevenness. In one or more embodiments, when the layer to be etched is a cobalt film, the etching rate in the etching process of this disclosure is 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, from the viewpoint of improving productivity, and preferably 10 g / min or less, more preferably 1 g / min or less, and even more preferably 0.1 g / min or less, from the viewpoint of reducing etching unevenness. In one or more embodiments, when the layer to be etched is a titanium film, the etching rate in the etching process of this 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 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 process of this disclosure is 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, from the viewpoint of improving productivity, and preferably 10 g / min or less, more preferably 1 g / min or less, and even more preferably 0.1 g / min or less, from the viewpoint of reducing etching unevenness.

[0047] The etching solution compositions and etching methods of the present disclosure can be used in one or more embodiments to etch metals in the manufacturing process of electronic devices, particularly semiconductor wafers. The etching solution composition and etching method of this disclosure can be suitably used in the production of semiconductor wafers in one or more embodiments. This improves etching uniformity and enhances productivity and yield. The etching solution compositions and etching methods of the present disclosure can be used in one or more embodiments to etch electrodes in the manufacturing process of electronic devices, particularly semiconductor memories such as non-volatile memories including NAND flash memory. The etching solution composition and etching method of this disclosure can be suitably used in one or more embodiments to produce patterns having a three-dimensional structure. This makes it possible to obtain advanced devices such as high-capacity memory. The etching solution composition and etching method of this disclosure can be used, for example, in etching methods such as those disclosed in Japanese Patent Application Publication No. 2020-145412. [Examples]

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

[0049] 1. Preparation of etching solution (Examples 1-9) Etching solutions (pH: -1) for Examples 1 to 9 were obtained by combining the etching inhibitors shown in Table 1, mixed acid (phosphoric acid / acetic acid / nitric acid, mass ratio: 88 / 8 / 4), and water. Note that the mass ratio of the mixed acid is calculated on a mass basis. (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 of 76 / 7 / 3 / 14 (phosphoric acid / acetic acid / nitric acid / water). (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 combined to obtain the etching solution of Comparative Example 2 (pH: -1). (Comparative Example 3) The etching inhibitor for Comparative Example 3 (pH:-1) was obtained by combining the etching inhibitor (polyethyleneimine), hydrogen peroxide, phosphoric acid, and water shown in Table 1. Table 1 shows the proportions (mass %) and effective content of each component in the prepared etching solution. Note that the water proportions in Table 1 include water contained in acidic aqueous solutions and hydrogen peroxide solutions.

[0050] The following components were used to prepare the etching solution. (Etching 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 Nitto Boseki Medical Co., Ltd.] N-(2-hydroxyethyl)piperazine [Molecular weight 130, Nippon Emulsifier Co., Ltd.] DL-Arginine [Molecular weight 174, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.] (hydrogen peroxide) H2O2 [Hydrogen peroxide, 35% by mass, manufactured by ADEKA Corporation] (acid) Phosphoric acid [manufactured by Phosphorus Chemical Industry Co., Ltd., concentration 85%] Acetic acid [Fujifilm Wako Pure Chemical Industries, Ltd., 100% concentration] Nitric acid [Fujifilm Wako Pure Chemical Industries, Ltd., 70% concentration] (water) Water [Ultrapure water produced using a continuous pure water production system (PureConti PC-2000VRL model) and subsystem (MacAce KC-05H model) manufactured by Kurita Water Industries Ltd.]

[0051] 2. Measurement methods for each parameter [pH of etching solution] The pH value of the etching solution at 25°C was measured using a pH meter (manufactured by Toa DKK Co., Ltd.), and the value was obtained one minute after immersing the pH meter's electrode in the etching solution.

[0052] 3-1. Evaluation of the etching solution (Etched layer: Tungsten plate) [Evaluation of etching rate and etching suppression rate of tungsten plates] Tungsten plates, measuring 2 cm in length, 2 cm in width, and 0.1 mm in thickness, whose weight had been measured beforehand, were immersed in etching solutions prepared for each composition (Examples 1-9 and Comparative Examples 1-3). The tungsten plates were etched at 90°C for 120 minutes. After rinsing with water, the weight of the tungsten plates was measured again, and the difference was determined as the etching amount. A precision balance was used to measure the weight. The etching rate of the tungsten plate was then determined using the following formula. Etching rate (g / min) = Amount etched (g) / Etching time (min) The etching rates of the tungsten plates are shown in Table 1 as relative values ​​(relative speeds) with Comparative Example 1 set to 100. Furthermore, the etching suppression rate (%) is shown in Table 1, calculated by subtracting the relative speed of each example (with Comparative Example 1's etching rate set to 100) from 100. The etching rate and etching suppression rate can be evaluated using a molybdenum plate measuring 2 cm in length, 2 cm in width, and 0.1 mm in thickness, or the wafer shown in Figure 1 of Japanese Patent Application Publication No. 2020-145412, instead of a tungsten plate measuring 2 cm in length, 2 cm in width, and 0.1 mm in thickness.

[0053] [Evaluation of etching irregularities in tungsten plates (surface accuracy)] Tungsten plates, each 2 cm long, 2 cm wide, and 0.1 mm thick, whose weight had been measured beforehand, were immersed in etching solutions prepared for each composition (Examples 1-9 and Comparative Examples 1-3). The tungsten plates were etched at 90°C for 120 minutes. After rinsing with water, the surface of the tungsten plates was observed again using a KEYENCE VK-9710 shape-measuring laser microscope (lens magnification 150x), and the resulting images were analyzed using the surface roughness mode of the same device. The surface accuracy (etching unevenness) was then determined. The surface accuracy of the tungsten plates was evaluated based on the following evaluation criteria, and the results are shown in Table 1. Surface accuracy (%) = Surface roughness after etching / Surface roughness before etching × 100 <Evaluation Criteria> 5: Surface accuracy less than 120% 4: Surface accuracy between 120% and less than 200% 3: Surface accuracy between 200% and less than 300% 2: Surface accuracy between 300% and less than 500% 1: Surface accuracy between 500% and less than 700% 0: Surface accuracy of 700% or more Furthermore, the evaluation of etching irregularities can be performed using a molybdenum plate measuring 2 cm in length, 2 cm in width, and 0.1 mm in thickness, or the wafer shown in Figure 1 of Japanese Patent Application Publication No. 2020-145412, instead of a tungsten plate measuring 2 cm in length, 2 cm in width, and 0.1 mm in thickness.

[0054] [Zeta potential] To each of the etching solutions prepared to different compositions (Examples 1-9 and Comparative Examples 1-3), a 100 ppm tungsten standard solution was added to prepare samples for zeta potential measurement. A precision balance was used to measure the weight. The 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 rate: 0.390 Dispersion medium: viscosity: 39cP, refractive index: 1.426 Temperature: 25℃

[0055] [Table 1]

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

[0057] Furthermore, the etching solutions of Examples 1, 3-4 and Comparative Examples 1-3 were used for the following evaluations.

[0058] 3-2. Evaluation of etching solution (Etched layer: Nickel plate) [Evaluation of etching rate and etching suppression rate of nickel plates] The nickel plate was etched in the same manner as the tungsten plate, 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. The etching rate of the nickel plate was then measured. The results of the etching rate of the nickel plate are shown in Table 2. In addition, the etching inhibition rate (%) was calculated by subtracting the relative etching rate of each example from 100, with the etching rate of Comparative Example 1 set to 100, and this value is also shown in Table 2.

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

[0060] [Table 2]

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

[0062] 3-3. Evaluation of the etching solution (Etched layer: Cobalt plate) [Evaluation of etching rate and etching suppression rate of cobalt plates] The etching of the cobalt plate was carried out in the same manner as the etching of the tungsten plate, 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. The etching rate of the cobalt plate was then measured. The results of the etching rate of the cobalt plate are shown in Table 3. In addition, the etching inhibition rate (%) was calculated by subtracting the relative etching rate of each example from 100, with the etching rate of Comparative Example 1 set to 100, and is shown in Table 3.

[0063] [Evaluation of etching irregularities in cobalt plates (surface accuracy)] Cobalt plates, each 2 cm long, 2 cm wide, and 0.1 mm thick, whose weight had been measured beforehand, were immersed in the prepared etching solutions (Examples 1, 3-4, and Comparative Examples 1-3). The cobalt plates were etched at 40°C for 10 minutes. After rinsing with water, the surface of the cobalt plates was observed again using a KEYENCE VK-9710 shape-measuring laser microscope (lens magnification 150x), and the resulting photographs were analyzed using the surface roughness mode of the same device. The surface accuracy (etching unevenness) was then determined. The surface accuracy of the cobalt plates was evaluated based on the same evaluation criteria as the tungsten surface accuracy evaluation described above, and the results are shown in Table 3.

[0064] [Table 3]

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

[0066] 3-4. Evaluation of the etching solution (Etched layer: Titanium plate) [Evaluation of etching rate and etching suppression rate of titanium plates] Except for using a titanium plate measuring 2 cm in length, 2 cm in width, and 0.1 mm in thickness instead of the tungsten plate, the titanium plate was etched in the same manner as the tungsten plate etching method, and the etching rate of the titanium plate was measured. The results of the etching rate of the titanium plate are shown in Table 4. In addition, the etching inhibition rate (%) was calculated by subtracting the relative etching rate of each example from 100, with the etching rate of Comparative Example 1 set to 100, and is shown in Table 4.

[0067] [Evaluation of etching irregularities in titanium plates (surface accuracy)] Titanium plates, 2 cm long, 2 cm wide, and 0.1 mm thick, whose weight had been measured in advance, were immersed in the prepared etching solutions (Examples 1, 3-4, and Comparative Examples 1-3). The titanium plates were etched at 90°C for 120 minutes. After rinsing with water, the surface of the cobalt plates was observed again using a KEYENCE VK-9710 shape-measuring laser microscope (lens magnification 150x), and the resulting photographs were analyzed using the surface roughness mode of the same device. The surface accuracy (etching unevenness) was then determined. The surface accuracy of the titanium plates was evaluated based on the same evaluation criteria as the tungsten surface accuracy evaluation described above, and the results are shown in Table 4.

[0068] [Table 4]

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

[0070] 3-5. Evaluation of the etching solution (Etched layer: copper plate) [Evaluation of etching rate and etching suppression rate of copper plates] Except for using a copper plate measuring 2 cm in length, 2 cm in width, and 0.1 mm in thickness instead of the tungsten plate, and changing the etching conditions to an etching temperature of 40°C and an etching time of 10 minutes, the copper plate was etched in the same manner as the tungsten plate etching method, and the etching rate of the copper plate was measured. The results of the etching rate of the copper plate are shown in Table 5. In addition, the etching inhibition rate (%) was calculated by subtracting the relative etching rate of each example from 100, with the etching rate of Comparative Example 1 set to 100, and is shown in Table 5.

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

[0072] [Table 5]

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

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

Claims

1. An etching solution composition for etching a layer to be etched, comprising at least one metal, The etching solution composition comprises an etching inhibitor, an acid containing at least nitric acid, and water, and has a pH of 1 or less. The etching solution composition wherein the etching inhibitor is at least one nitrogen-containing compound selected from polymers containing polyalkylene imines and diallylamine-derived structural units.

2. The etching solution composition according to claim 1, wherein the etching inhibitor is polyethyleneimine.

3. An etching solution composition for etching a layer to be etched containing at least one metal, The etching solution composition contains an etching inhibitor, an acid including phosphoric acid, acetic acid, and nitric acid, and water, and has a pH of 1 or less. The etching solution composition wherein the etching inhibitor is a nitrogen-containing compound that has an etching inhibition rate of 30% or more, as determined under the following conditions. Here, the etching inhibition rate is defined as the relative etching rate A of the etching solution composition, which is set to 100 when etching is performed at a predetermined temperature and time using a mixed acid aqueous solution consisting of phosphoric acid, acetic acid, nitric acid, and water, wherein the mass ratio of the amounts of phosphoric acid, acetic acid, and nitric acid is the same as the mass ratio of the amounts of phosphoric acid, acetic acid, and nitric acid in the etching solution composition, and the total amount of phosphoric acid, acetic acid, and nitric acid is 86% by mass, and the etching rate is set to 100.

4. An etching solution composition for etching a layer to be etched containing at least one metal, 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 solution composition wherein the etching inhibitor is a nitrogen-containing compound that can raise the zeta potential of the metal surface contained in the layer to be etched to more than 0 mV and less than or equal to 50 mV.

5. The etching solution composition according to any one of claims 1 to 4, wherein the average molecular weight of the etching inhibitor is 300 or more.

6. The etching solution composition according to claim 1 or 4, wherein the acid further comprises at least one selected from phosphoric acid and acetic acid in addition to nitric acid.

7. The etching solution composition according to any one of claims 1 to 6, wherein the etching solution composition does not contain hydrogen peroxide.

8. The etching solution composition according to any one of claims 1 to 7, wherein the metal is at least one metal selected from tungsten, tantalum, zirconium, hafnium, molybdenum, niobium, ruthenium, osmium, rhenium, rhodium, copper, nickel, cobalt, titanium, titanium nitride, alumina, aluminum, and iridium.

9. An etching method comprising the step of etching a layer to be etched, which contains at least one metal, using an etching solution composition according to any one of claims 1 to 8.

Images