JP7713853B2 - Etching solution composition - Google Patents

Description

This disclosure relates to an etching solution composition, and an etching method and a substrate processing method using the same.

In the manufacturing process of a semiconductor device, a process is performed in which a film to be etched containing at least one metal such as tungsten, tantalum, zirconium, hafnium, molybdenum, niobium, ruthenium, osmium, rhenium, rhodium, copper, nickel, cobalt, titanium, titanium nitride, alumina, aluminum, iridium, etc. is etched into a predetermined pattern shape. As an etching solution, a mixed acid solution containing phosphoric acid, nitric acid, and acetic acid is generally used.
In recent years, the semiconductor field has seen an increase in integration density, which has led to a demand for more complex and finer wiring. This has resulted in increased demands for pattern processing techniques and etching solutions, and various etching solution compositions have been proposed.

For example, Patent Document 1 proposes an etching solution composition containing phosphoric acid, nitric acid, methoxyacetic acid, and water as an etching solution composition for etching a metal thin film containing silver as a main component.
Patent Document 2 proposes an etching solution composition for etching a metal oxide containing indium or a metal oxide containing zinc and indium, the etching solution composition containing at least one kind of basic acid (phosphoric acid, nitric acid, etc.) and water, in which the acid dissociation constant pKa at 25° C. in any of the dissociation stages of the basic acid is 2.15 or less and the hydrogen ion concentration pH at 25° C. is 4 or less.
Patent Document 3 proposes a method of simultaneously etching a tungsten film and a titanium nitride film using an etching solution composition containing hydrogen peroxide, phosphoric acid, an amine or amide polymer, sulfuric acid, and deionized water.

JP 2006-253473 A JP 2015-60937 A Korean Patent Publication No. 10-2014-0065771

As an etching solution, a mixed acid aqueous solution (strong acid aqueous solution) containing phosphoric acid, nitric acid, and acetic acid is generally used. Patent Document 3 proposes adding polyethyleneimine as an agent for suppressing etching and improving etching selectivity, but it has been found that adding polyethyleneimine or the like to the mixed acid aqueous solution causes turbidity and deteriorates the storage stability of the etching solution. Furthermore, deterioration of the storage stability of the etching solution affects filterability. Therefore, there is a demand for an etching solution that contains phosphoric acid and nitric acid and can maintain storage stability and filterability even when it further contains polyethyleneimine or the like.

Therefore, in one aspect, the present disclosure provides an etching solution composition that contains phosphoric acid and nitric acid, and can maintain storage stability and filterability even when it further contains an etching inhibitor such as polyethyleneimine.

In one aspect, the present disclosure relates to an etching solution composition for etching a metal film formed on a substrate, the etching solution composition containing phosphoric acid, nitric acid, an organic acid having a solubility in water at 20°C of 900 g/L or less, an etching inhibitor, and water, the etching inhibitor being an amine compound having no carboxyl group, and the metal film being a metal film containing 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.

In one aspect, the present disclosure relates to an etching method that includes a step of etching a metal film containing at least one metal using an etching solution composition of the present disclosure.

In one aspect, the present disclosure relates to a substrate processing method that includes a step of etching a metal film formed on a substrate using an etching solution composition of the present disclosure, the substrate being at least one type of substrate selected from a semiconductor wafer, a substrate for a liquid crystal display device, a substrate for a plasma display, a substrate for an FED (Field Emission Display), a substrate for an optical disk, a substrate for a magnetic disk, a substrate for a magneto-optical disk, a substrate for a photomask, a ceramic substrate, and a substrate for a solar cell.

According to one aspect of the present disclosure, an etching solution composition can be provided that contains phosphoric acid and nitric acid, and further contains an etching inhibitor, while maintaining storage stability and filterability.

In one aspect, the present disclosure is based on the finding that storage stability and filterability can be maintained by using an etching solution containing phosphoric acid, nitric acid, an organic acid having a solubility in water at 20°C of 900 g/L or less, an etching inhibitor, and water.

In one aspect, the present disclosure relates to an etching solution composition for etching a metal film formed on a substrate, the etching solution composition comprising phosphoric acid, nitric acid, an organic acid having a solubility in water at 20° C. of 900 g/L or less, an etching inhibitor, and water, wherein the etching inhibitor is an amine compound having no carboxyl group, and the metal film is a metal film containing 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 (hereinafter also referred to as the "etching solution composition of the present disclosure").
According to the etching solution composition of the present disclosure, even if it contains phosphoric acid and nitric acid and further contains an etching inhibitor, it is possible to maintain storage stability and filterability.

Although the details of the mechanism by which the effects of the present disclosure are manifested are not clear, it is presumed as follows.
When an etching inhibitor is added to an etching solution containing phosphoric acid and nitric acid (strong acid aqueous solution), the etching inhibitor and nitric acid form a poorly soluble salt, causing turbidity.
When an organic acid having a solubility in water of more than 900 g/L is used as the organic acid, it is considered that the organic acid is highly hydrophilic and therefore does not easily dissolve a poorly soluble salt in a strongly acidic aqueous solution, causing turbidity.
Furthermore, when the etching inhibitor is an amine compound having a carboxyl group, many of the amine compounds are relatively hydrophilic compounds. Therefore, even if an organic acid having a solubility in water of 900 g/L or less is used as the organic acid, it becomes difficult to dissolve a poorly soluble salt, and turbidity is likely to occur.
In the present disclosure, it is considered that an organic acid having a solubility in water of 900 g/L or less dissolves a poorly soluble salt formed by an amine compound having no carboxyl group and nitric acid in a strongly acidic aqueous solution, thereby suppressing the generation of turbidity and maintaining the storage stability and filterability of the etching solution.
However, the present disclosure need not be construed as being limited to these mechanisms.

[phosphoric acid]
The amount of phosphoric acid in the etching solution composition of the present disclosure is, from the viewpoints of the etching rate, and of maintaining storage stability and filterability, preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more, and from the viewpoint of filterability, preferably 90% by mass or less, more preferably 85% by mass or less, even more preferably 80% by mass or less, even more preferably 70% by mass or less, and even more preferably 65% by mass or less.

[nitric acid]
The amount of nitric acid blended in the etching solution composition of the present disclosure is, from the viewpoint of etching rate, preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 1.5% by mass or more, even more preferably 2% by mass or more, even more preferably 3% by mass or more, and even more preferably 4% by mass or more, and from the viewpoint of etching unevenness, is preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 7% by mass or less, and even more preferably 6% by mass or less.

[Organic acid]
From the viewpoint of maintaining storage stability and filterability, examples of organic acids having a solubility of 900 g/L or less in water at 20° C. that are contained in the etching solution composition of the present disclosure include methoxyacetic acid (solubility: 485 g/L), citric acid (solubility: 592 g/L), succinic acid (solubility: 58 g/L), 3-methoxybutyl acetate (solubility: 4.6 g/L), etc. The organic acids having a solubility of 900 g/L or less in water at 20° C. may be used alone or in combination of two or more.

The amount of organic acid having a solubility of 900 g/L or less in water at 20°C in the etching solution composition of the present disclosure is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more, from the viewpoint of maintaining storage stability and filterability, and from the same viewpoint, is preferably 90% by mass or less, more preferably 80% by mass or less, even more preferably less than 70% by mass, even more preferably less than 60% by mass, even more preferably 50% by mass or less, and even more preferably 45% by mass or less. When two or more organic acids having a solubility of 900 g/L or less in water at 20°C are combined, the amount of organic acid having a solubility of 900 g/L or less in water at 20°C is the total amount of them.

The total amount of phosphoric acid, nitric acid, and organic acid having a solubility of 900 g/L or less in water at 20°C 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 maintaining storage stability and filterability, and 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. The total amount of phosphoric acid, nitric acid, and organic acid having a solubility of 900 g/L or less in water at 20°C 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.

[Etching Inhibitor]
The etching inhibitor contained in the etching liquid composition of the present disclosure is an amine compound having no carboxyl group. The etching inhibitor may be used alone or in combination of two or more.

In the present disclosure, from the viewpoints of reducing etching unevenness and maintaining storage stability and filterability, the etching inhibitor 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, 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 an etching inhibitor is not used. In one or more embodiments, the etching inhibition rate can be a value obtained by subtracting the relative etching rate A of the etching rate of the etching solution composition from 100 when the etching rate is 100 when etching is performed at a predetermined temperature and a predetermined time using a mixed acid aqueous solution consisting of phosphoric acid, nitric acid, an organic acid having a solubility of 900 g/L or less in water at 20°C, and water, the mass ratio of the phosphoric acid, nitric acid, and the organic acid having a solubility of 900 g/L or less in water at 20°C is the same as the mass ratio of the phosphoric acid, nitric acid, and the organic acid having a solubility of 900 g/L or less in water at 20°C in the etching solution composition, and the total amount of the phosphoric acid, nitric acid, and the organic acid having a solubility of 900 g/L or less in water at 20°C is 87% by mass. The mass ratio of the amounts of the components in the mixed acid aqueous solution can be set appropriately. In one or more embodiments, the etching inhibition rate can be measured by adapting the implementation conditions such as temperature and time to the conditions for performing etching. The measurement conditions for the etching inhibition rate vary depending on the metal contained in the layer to be etched. For example, 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 process of the present disclosure described below.

The etching inhibitor in the present disclosure is an amine compound having no carboxyl group, and examples thereof include at least one selected from polyalkyleneimines and polyalkylenepolyamines.
The polyalkyleneimine may, for example, be polyethyleneimine (PEI).
Examples of the polyalkylene polyamine include pentaethylenehexamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine.

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, and even more preferably 1,200 or more from the viewpoint of reducing etching unevenness and maintaining storage stability and filterability, and is preferably 100,000 or less, more preferably 5,000 or less, and even more preferably 3,000 or less from the viewpoint of viscosity. From the same viewpoint, 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, and even more preferably 1,200 or more and 3,000 or less.
When the etching inhibitor is a polyalkylene polyamine, the weight average molecular weight of the etching inhibitor is preferably 50 or more, more preferably 80 or more, and even more preferably 100 or more, from the viewpoints of reducing etching unevenness and maintaining storage stability and filterability, and from the same viewpoint, it is preferably 1,000 or less, more preferably 500 or less, and even more preferably 300 or less. From the same viewpoint, the weight average molecular weight of the etching inhibitor is preferably 50 or more and 1,000 or less, more preferably 80 or more and 500 or less, and even more preferably 100 or more and 300 or less.

In this disclosure, the average molecular weight can be measured by gel permeation chromatography (GPC).
An example of a method for measuring the average molecular weight of the etching inhibitor of the present disclosure is shown below.
<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: 1.0mL/min
Sample solution injection volume: 100 μL
Standard polymer: pullulan with known molecular weight (Shodex P-5, P-50, P-200, P-800)

The amount of the 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 and maintaining storage stability and filterability, and from the same viewpoint, it is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 3% by mass or less, and even more preferably 2% by mass or less. From the same viewpoint, the amount of the 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, even more preferably 0.5% by mass or more and 3% by mass or less, and even more preferably 0.5% by mass or more and 2% by mass or less. When two or more etching inhibitors are used in combination, the amount of the etching inhibitor is the total amount of the etching inhibitors.

[water]
In one or more embodiments, the etching solution composition of the present disclosure contains water. Examples of the water contained in the etching solution of the present disclosure include distilled water, ion-exchanged water, pure water, and ultrapure water.
The amount of water in the etching solution composition of the present disclosure is preferably 2% by mass or more, more preferably 5% by mass or more, even more preferably 7% by mass or more, and even more preferably 10% by mass or more, from the viewpoint of maintaining storage stability and filterability, and from the same viewpoint, it is preferably 35% by mass or less, more preferably 30% by mass or less, even more preferably 25% by mass or less, and even more preferably 20% by mass or less. From the same viewpoint, the amount of water in the etching solution composition of the present disclosure is preferably 2% by mass or more and 35% by mass or less, more preferably 5% by mass or more and 30% by mass or less, even more preferably 7% by mass or more and 25% by mass or less, and even more preferably 10% by mass or more and 20% by mass or less.

[Other ingredients]
The etching solution composition of the present disclosure may further contain other components within the scope of the present disclosure, such as inorganic acids other than phosphoric acid and nitric acid, organic acids other than organic acids having a solubility in water at 20° C. of 900 g/L or less, chelating agents, surfactants, solubilizing agents, preservatives, rust inhibitors, germicides, antibacterial agents, antioxidants, etc.

From the viewpoint of reducing etching unevenness, the etching solution composition of the present disclosure preferably does not contain hydrogen peroxide. Here, "does not contain hydrogen peroxide" includes, in one or more embodiments, not containing hydrogen peroxide, not containing substantially hydrogen peroxide, or not containing an amount of hydrogen peroxide that affects the etching result. The amount of hydrogen peroxide in the etching solution composition of the present disclosure is not particularly limited, but is preferably less than 1 mass%, more preferably 0.5 mass% or less, even more preferably 0.1 mass% or less, even more preferably 0.01 mass% or less, and even more preferably 0 mass%.

In one or more embodiments, the etching solution composition of the present disclosure does not become turbid at 25°C. The occurrence or nonoccurrence of turbidity can be confirmed by the method described in the Examples.

[Method of producing etching solution composition]
In one embodiment, the etching solution composition of the present disclosure is obtained by blending phosphoric acid, nitric acid, an organic acid having a solubility of 900 g/L or less in water at 20° C., an etching inhibitor, water, and, if desired, the optional components described above, by a known method. Thus, in one embodiment, 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") that includes a step of blending at least phosphoric acid, nitric acid, an organic acid having a solubility of 900 g/L or less in water at 20° C., an etching inhibitor, and water.
In the present disclosure, "blending at least phosphoric acid, nitric acid, an organic acid having a solubility in water at 20° C. of 900 g/L or less, an etching inhibitor, and water" includes, in one or more embodiments, simultaneously or sequentially mixing phosphoric acid, nitric acid, an organic acid having a solubility in water at 20° C. of 900 g/L or less, an etching inhibitor, water, and the above-mentioned optional components as necessary. The order of mixing is not particularly limited. The blending can be performed using a mixer such as a propeller-type agitator, liquid circulation agitation by a pump, a homomixer, a homogenizer, an ultrasonic disperser, and a wet ball mill.
In the method for producing an etching solution according to the present disclosure, the preferred amount of each component may be the same as the preferred amount of each component in the etching solution composition according to the present disclosure described above.

In the present disclosure, the "amount of each component in the etching solution composition" refers, in one or a plurality of embodiments, to the amount of each component in the etching solution composition used in the etching step, i.e., at the time when the use in the etching treatment is started (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 regarded as the content of each component in the etching solution composition of the present disclosure. However, when the component is affected by neutralization, the blending amount and the content may differ.

Embodiments of the etching solution composition of the present disclosure may be so-called one-liquid type, in which all components are supplied to the market in a premixed state, or so-called two-liquid type, in which components are mixed at the time of use. Examples of two-liquid type etching solution compositions include those in which water is separated into a first liquid and a second liquid, phosphoric acid, nitric acid, an organic acid with a solubility in water at 20°C of 900 g/L or less, and an etching inhibitor are each contained in either or both of the first liquid and the second liquid, and the first liquid and the second liquid are mixed at the time of use. The first liquid and the second liquid may each contain the optional components described above as necessary.

From the viewpoint of maintaining storage stability and filterability, the pH of the etching solution composition of the present disclosure is preferably 1 or less, more preferably 0 or less, even 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.

The etching solution composition of the present disclosure may be stored and supplied in a concentrated state to the extent that its storage stability is not impaired. In this case, it is preferable in that production and transportation costs can be reduced. This concentrated solution can be appropriately diluted with water or an aqueous acid solution as necessary and used in the etching process. The dilution ratio can be, for example, 3 to 100 times.

[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”).
In one or more embodiments, the kit of the present disclosure includes a kit (two-liquid etching solution) that contains a first liquid and a second liquid in a mutually unmixed state, and phosphoric acid, nitric acid, an organic acid having a solubility of 900 g/L or less in water at 20° C., and an etching inhibitor are contained in either one or both of the first liquid and the second liquid, and the first liquid and the second liquid are mixed when used. After the first liquid and the second liquid are mixed, they may be diluted with water or an acid aqueous solution as necessary. The first liquid or the second liquid may contain all or a part of the water used to prepare the etching solution. The first liquid and the second liquid may each contain the above-mentioned optional components as necessary.
For example, the kit of the present disclosure includes a kit (two-liquid etching solution) that contains a solution (1a liquid) containing an etching inhibitor and an acid aqueous solution (2a liquid) containing phosphoric acid, nitric acid, and an organic acid having a solubility in water at 20 ° C. of 900 g / L or less in a mutually unmixed state, and is mixed at the time of use. After the 1a liquid and the 2a liquid are mixed, they may be diluted with water or an acid aqueous solution as necessary. The 1a liquid or the 2a liquid may contain all or a part of the water used to prepare the etching solution. The acid contained in the 2a liquid may be all or a part of the acid used to prepare the etching solution. The 1a liquid may contain an acid. The 1a liquid and the 2a liquid may each contain the above-mentioned optional components as necessary.
According to the kit of the present disclosure, an etching solution can be obtained that contains phosphoric acid and nitric acid and further contains an etching inhibitor, while maintaining storage stability and filterability.

[Film to be etched]
In one or more embodiments, the film to be etched using the etching solution composition of the present disclosure is a metal film containing at least one metal.Here, the metal film is not particularly limited as long as the effects of the present disclosure are achieved, but examples thereof include metal films containing 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.In one or more embodiments, the metal film does not contain silver.
In one or more embodiments, the etching solution composition of the present disclosure is preferably used for etching a metal film (not including silver) containing at least one metal selected from tungsten, tantalum, zirconium, molybdenum, niobium, and nickel, and is preferably used for etching a tungsten film, a molybdenum film, or a nickel film. That is, in one or more embodiments, the film to be etched is a tungsten film, a molybdenum film, or a nickel film.

[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 metal film containing at least one metal using the etching solution composition of the present disclosure (hereinafter also referred to as the "etching step of the present disclosure"). According to the etching method of the present disclosure, the productivity of semiconductor substrates can be improved by using an etching solution that contains phosphoric acid and nitric acid and maintains storage stability and filterability even when further containing an etching inhibitor.

In the etching process of the present disclosure, examples of the etching method include immersion etching and single-wafer etching.

In one or more embodiments, when the film to be etched is a tungsten film, the temperature (etching temperature) of the etching solution composition in the etching step of the present disclosure 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. From the same viewpoint, in one or more embodiments, when the film 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 film to be etched is a molybdenum film, the temperature (etching temperature) of the etching solution composition in the etching step of the present disclosure 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. From the same viewpoint, in one or more embodiments, when the film 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 film to be etched is a nickel film, the temperature (etching temperature) of the etching solution composition in the etching step of the present disclosure 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. From the same viewpoint, in one or more embodiments, when the film 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 the etching process of the present disclosure, the etching time can be set, for example, to 1 minute or more and 180 minutes or less.

In one or a plurality of embodiments, when the film to be etched is a tungsten film, from the viewpoint of improving productivity, the etching rate in the etching step of the present 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, and from the viewpoint of reducing etching unevenness, it is 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 a plurality of embodiments, when the film to be etched is a molybdenum film, from the viewpoint of improving productivity, the etching rate in the etching step of the present 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, and from the viewpoint of reducing etching unevenness, is 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 a plurality of embodiments, when the film 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, 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 a plurality of embodiments, the etching solution composition and the etching method of the present disclosure can be used to etch metals in the manufacturing process of electronic devices, particularly semiconductor wafers.
In one or more embodiments, the etching solution composition of the present disclosure and the etching method of the present disclosure can be suitably used for the preparation of at least one substrate selected from a semiconductor wafer, a substrate for a liquid crystal display device, a substrate for a plasma display device, a substrate for an FED (Field Emission Display), a substrate for an optical disk, a substrate for a magnetic disk, a substrate for a magneto-optical disk, a substrate for a photomask, a ceramic substrate, and a substrate for a solar cell. That is, in one aspect, the present disclosure relates to a substrate processing method (hereinafter also referred to as the "substrate processing method of the present disclosure") that includes a step of etching a metal film formed on a substrate using the etching solution composition of the present disclosure or the etching method of the present disclosure, and the substrate is at least one substrate selected from a semiconductor wafer, a substrate for a liquid crystal display device, a substrate for a plasma display device, a substrate for an FED (Field Emission Display), a substrate for an optical disk, a substrate for a magnetic disk, a substrate for a magneto-optical disk, a substrate for a photomask, a ceramic substrate, and a substrate for a solar cell. According to the substrate processing method of the present disclosure, by using an etching solution composition that contains phosphoric acid and nitric acid and that maintains storage stability and filterability even when an etching inhibitor is further contained, the productivity and yield of semiconductor substrates can be improved.
In one or a plurality of 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 making it possible to obtain an advanced device such as a large-capacity memory.
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 JP2020-145412A.

The present disclosure will be explained in detail below with reference to examples, but the present disclosure is not limited to these examples.

1. Preparation of Etching Solution (Examples 1 to 9, Comparative Examples 1 and 2, Reference Example 1)
Phosphoric acid, nitric acid, an organic acid shown in Table 1, an etching inhibitor shown in Table 1, and water were mixed to obtain etching solutions (pH: -1) of Examples 1 to 9, Comparative Examples 1 and 2, and Reference Example 1.
The amount of each component (mass %, effective amount) in the prepared etching solution is shown in Table 1. The amount of water in Table 1 includes the amount of water contained in the acid aqueous solution, etc.

The following components were used to prepare the etching solution.
Phosphoric acid [Rinkagaku Kogyo Co., Ltd., concentration 85%]
Nitric acid [FUJIFILM Wako Pure Chemical Corporation, concentration 70%]
(organic acid)
Acetic acid [FUJIFILM Wako Pure Chemical Industries, Ltd., concentration 100%, solubility in water at 20°C: 1000 g/L]
Methoxyacetic acid [FUJIFILM Wako Pure Chemical Industries, Ltd., concentration 95%, solubility in water at 20°C: 485 g/L]
(Etching Inhibitor)
Polyethyleneimine [number average molecular weight 1,800, "Epomin SP-018" manufactured by Nippon Shokubai Co., Ltd.]
Pentaethylenehexamine ["PEHA" manufactured by Tosoh Corporation]
(water)
Water [ultrapure water produced using a continuous pure water production system (Pure Conti PC-2000VRL type) and subsystem (Macace KC-05H type) manufactured by Kurita Water Industries Ltd.]

2. Parameter measurement method [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.

3. Evaluation of the etching solution [Whether or not turbidity occurs (storage stability)]
The etching solution composition immediately after preparation was visually inspected for the presence or absence of turbidity under the following conditions. The results are shown in Table 1.
<Conditions and Facilities>
Temperature of liquid composition: 25°C
Container: 100 ml transparent glass container. Method of blending liquid composition: Predetermined amounts of phosphoric acid, nitric acid, an organic acid having a solubility in water at 20° C. of 900 g/L or less, an etching inhibitor, and water described in the examples were blended while stirring at 200 rpm using a magnetic stirrer. The order of blending may be changed.
Check for cloudiness: After stirring for 30 minutes at 200 rpm using a magnetic stirrer, the etching solution composition was allowed to stand for 5 minutes, and then visually checked for cloudiness. The visual check was performed by one experienced researcher.

[Filterability]
The etching solution composition was passed through the filter under the following conditions: Filterability was "A" when the entire amount of 50 kg of the prepared scale was passed, "B" when the amount of the passed liquid was 20 kg or more and less than 50 kg, "C" when the amount of the passed liquid was 5 kg or more and less than 20 kg, and "D" when the filter was clogged and filtering was not possible (less than 5 kg of the prepared scale).
<Conditions and Facilities>
Liquid temperature: 25℃
Filtration pressure: 0.3MPa
Filtration flow rate: 5 kg/min
Scale: 50 kg of etching solution composition
Pump: Diaphragm pump DP-10BPT (manufactured by Yamada Corporation)
Piping: PFA piping (outer diameter 19φ, manufactured by Fluorochemical Co., Ltd.)
Filter: Clanfil (PTFE, pore size 0.05 μm, manufactured by Kurabo Industries, Ltd.)
Container: 10L container

As shown in Table 1, the etching solutions of Examples 1 to 9, which use a combination of an organic acid (methoxyacetic acid) with a solubility of 900 g/L or less in water at 20°C and an etching inhibitor, do not become turbid, maintain storage stability and filterability, and are able to suppress clogging of the filter when the etching solution is used.

The etching solution composition of the present disclosure is useful for etching metal films on semiconductor wafers, substrates for liquid crystal displays, substrates for plasma displays, substrates for FEDs (Field Emission Displays), substrates for optical disks, substrates for magnetic disks, substrates for magneto-optical disks, substrates for photomasks, ceramic substrates, and substrates for solar cells.

Claims (9)

An etching solution composition for etching a metal film formed on a substrate, comprising:
The solution contains phosphoric acid, nitric acid, an organic acid having a solubility in water at 20° C. of 900 g/L or less, an etching inhibitor, and water,
the etching inhibitor is an amine compound having no carboxyl group, and is at least one selected from polyalkyleneimines and polyalkylenepolyamines ;
The amount of the organic acid is 20% by mass or more,
The etching solution composition, wherein the metal film is a metal film containing 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. The etching solution composition according to claim 1 , wherein the content of the phosphoric acid is 20% by mass or more and 90% by mass or less . The etching solution composition according to claim 1 or 2, wherein the organic acid is methoxyacetic acid. The etching solution composition according to any one of claims 1 to 3, wherein the etching solution does not become turbid at 25°C. 5. The etching solution composition according to claim 1, wherein the etching inhibitor is at least one selected from the group consisting of polyethyleneimine, pentaethylenehexamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine. The etching solution composition according to any one of claims 1 to 5, wherein the substrate is at least one type of substrate selected from a semiconductor wafer, a substrate for a liquid crystal display device, a substrate for a plasma display, a substrate for an FED (Field Emission Display), a substrate for an optical disk, a substrate for a magnetic disk, a substrate for a magneto-optical disk, a substrate for a photomask, a ceramic substrate, and a substrate for a solar cell. The etching solution composition according to any one of claims 1 to 6, wherein the amount of hydrogen peroxide is less than 1 mass%. An etching method comprising a step of etching a metal film containing at least one metal using the etching solution composition according to any one of claims 1 to 7. The method includes a step of etching a metal film formed on a substrate using the etching solution composition according to any one of claims 1 to 7,
The substrate is at least one type of substrate selected from a semiconductor wafer, a substrate for a liquid crystal display device, a substrate for a plasma display, a substrate for an FED (Field Emission Display), a substrate for an optical disk, a substrate for a magnetic disk, a substrate for a magneto-optical disk, a substrate for a photomask, a ceramic substrate, and a substrate for a solar cell.