JP7803826B2 - Substrate processing method and etching solution composition used therein - Google Patents

Description

This disclosure relates to a substrate processing method and an etching solution composition used therein.

2. Description of the Related Art In the manufacturing process of a semiconductor device, an etching step is performed in which a film to be etched containing a metal is etched into a predetermined pattern shape.
In recent years, the semiconductor industry has seen increasing integration density, which has led to demands for more complex and finer wiring. This has led to increased demands for pattern processing techniques and etching solutions, and various etching methods have been proposed.

For example, Patent Document 1 discloses that by controlling the molar ratio of phosphoric acid to water (P/W) in a mixed acid (etchant) containing phosphoric acid, nitric acid, and water to fall within a certain range, it is possible to suppress fluctuations in the etching rate and reduce variations in the amount of tungsten etched among a plurality of substrates.
Patent Document 2 discloses that in a laminate in which two types of metal films and insulating layers are alternately stacked, when etching two types of metal films (including tungsten) between insulating layers (for example, when etching from FIG. 1A to FIG. 1B), the etching rate of an etching solution containing phosphoric acid, acetic acid, and nitric acid is changed (for example, the etching rate is lowered), thereby enabling efficient etching of the two types of metal films.

JP 2018-164034 A Japanese Patent Application Laid-Open No. 2020-145412

For example, when an aqueous mixed acid solution of phosphoric acid, acetic acid, and nitric acid is used as an etching solution, a film containing a metal such as tungsten can be etched at a high speed.
On the other hand, when the mixed acid aqueous solution is used as an etching solution, non-uniform etching may occur, resulting in loss of gloss on the metal film surface after etching. Loss of gloss can interfere with laser scattering measurement devices, making it impossible to accurately measure the surface cleanliness, shape, etc. In the semiconductor wafer manufacturing process, an etching solution that does not easily lose gloss is required from the viewpoints of productivity and yield.

In one aspect, the present disclosure provides a substrate processing method and an etching solution composition that can suppress the reduction in gloss of a metal film due to etching.

In one aspect, the present disclosure provides a substrate processing method including an etching step of etching an exposed portion of a metal film of a substrate having a metal film with an etching solution composition, the method comprising:
the metal film is any one of a tungsten film, a molybdenum film, an osmium film, an iridium film, a ruthenium film, a rhodium film, a copper film, and a nickel film;
the etching solution composition contains a mixed acid component, an etching inhibitor, and water, and has a pH of 1 or less;
the mixed acid component comprises phosphoric acid, an organic acid, and nitric acid;
the etching inhibitor is at least one organic amine compound selected from polyalkyleneimine, a polymer having a constitutional unit derived from diallylamine, and polyalkylenepolyamine;
the mass ratio of the mixed acid component to the etching inhibitor in the etching solution composition is 20 or more and 900 or less.

In one aspect, the present disclosure provides an etching solution composition for use in an etching step in a substrate processing method of the present disclosure, comprising:
The etching inhibitor includes a mixed acid component, an etching inhibitor, and water.
The pH is 1 or less,
the mixed acid component comprises phosphoric acid, an organic acid, and nitric acid;
the etching inhibitor is at least one organic amine compound selected from polyalkyleneimine, a polymer having a constitutional unit derived from diallylamine, and polyalkylenepolyamine;
The etching solution composition relates to a mass ratio of the mixed acid component to the etching inhibitor in the etching solution composition of 20 or more and 900 or less.

In one aspect, the present disclosure relates to a method for producing an etching solution composition of the present disclosure, the method including a step of blending a mixed acid composition containing a mixed acid component including phosphoric acid, an organic acid, and nitric acid with an etching inhibitor to obtain the etching solution composition.
In one aspect, the present disclosure relates to a mixed acid composition for use in the substrate processing method of the present disclosure or the method for producing an etching solution composition of the present disclosure, the mixed acid composition comprising a mixed acid component consisting of phosphoric acid, an organic acid, and nitric acid.

In one aspect, the present disclosure provides a substrate processing method and an etching solution composition that can suppress a decrease in the gloss of a metal film due to etching.

FIG. 1 is an explanatory diagram of an example of a substrate processing (etching process) according to the prior art.

In one aspect, the present disclosure is based on the finding that mixing a specific organic amine compound in a specific ratio relative to the amount of mixed acid component in an etching solution containing a mixed acid component made of phosphoric acid, an organic acid, and nitric acid reduces the etching rate without significantly impairing handleability, and further prevents the gloss of the metal film from decreasing due to etching.

In one aspect, the present disclosure provides a substrate processing method including an etching step of etching an exposed portion of a metal film of a substrate having a metal film with an etching solution composition, the method comprising:
the metal film is any one of a tungsten film, a molybdenum film, an osmium film, an iridium film, a ruthenium film, a rhodium film, a copper film, and a nickel film;
the etching solution composition contains a mixed acid component, an etching inhibitor, and water, and has a pH of 1 or less;
the mixed acid component comprises phosphoric acid, an organic acid, and nitric acid;
the etching inhibitor is at least one organic amine compound selected from polyalkyleneimine, a polymer having a constitutional unit derived from diallylamine, and polyalkylenepolyamine;
the mass ratio of the mixed acid component amount to the etching inhibitor amount in the etching solution composition is 20 or more and 900 or less (hereinafter also referred to as the "substrate processing method of the present disclosure").

The substrate processing method disclosed herein can, for example, suppress the reduction in gloss of a metal film due to etching without significantly impairing the handleability of the etching solution composition.

Although the details of the mechanism by which the effects of the present disclosure are manifested are not clear, it is presumed as follows.
The present disclosure uses an etching solution composition containing a mixed acid component consisting of phosphoric acid, an organic acid, and nitric acid, and an etching inhibitor, wherein the mass ratio of the mixed acid component to the etching inhibitor is within a predetermined range. This allows the etching inhibitor to form a dense coating or a thick protective film on the surface of the metal film to be etched, protecting the surface while etching slowly. This is thought to suppress uneven etching and reduce the gloss of the metal film due to etching. If the mass ratio of the mixed acid component to the etching inhibitor is too large, the amount of etching inhibitor relative to the amount of acid becomes too small, making it difficult to form a dense coating or a thick protective film on the surface of the metal film to be etched. This is thought to result in rapid etching by the acid, resulting in surface roughness and reduced gloss. On the other hand, if the mass ratio of the mixed acid component to the etching inhibitor is too small, the amount of etching inhibitor relative to the amount of acid is sufficient, preventing gloss reduction, but the viscosity of the etching composition increases, making it difficult to handle.
However, the present disclosure need not be construed as being limited to these mechanisms.

The substrate processing method disclosed herein can control the etching rate to a low level by adding an etching inhibitor to an etching solution containing a mixed acid component consisting of phosphoric acid, an organic acid, and nitric acid, and is therefore preferably applicable to substrate processing including etching processes that require a low etching rate.

[Substrate processing method]
The substrate processing method of the present disclosure includes an etching step of etching an exposed portion of a metal film of a substrate having a metal film thereon with an etching solution composition.

[substrate]
In one or more embodiments, the substrate to be processed by the substrate processing method of the present disclosure has a metal film as a film to be etched. In one or more embodiments, the film to be etched of the substrate to be processed is entirely or partially exposed so as to be contactable with an etching solution.
The substrate processing method of the present disclosure is capable of etching at a suppressed etching rate, and therefore can also process substrates having a structure for which a low etching rate is preferred, as disclosed in Patent Document 2 (for example, a substrate as shown in FIG. 1A ). In FIG. 1A , 100 denotes a polysilicon film, 101 denotes a tungsten film (film to be etched), 102 denotes a titanium nitride film (film to be etched), and 103 denotes an insulating layer (SiO ₂ layer). The film to be etched 102 in FIG. 1 may be a film other than a titanium nitride film, and the substrate may not have the film to be etched 102.
Therefore, in one or more embodiments, the substrate to be processed by the substrate processing method of the present disclosure may be a substrate having a laminate structure in which a metal film layer including a film to be etched and an insulating layer (e.g., a _SiO2 layer) are alternately and repeatedly stacked, in one or more embodiments, a substrate in which a part of the film to be etched of the substrate is exposed, and in one or more embodiments, a substrate in which the metal film layer is a layer including one or more metal films.

[Metal film]
The metal film, which is the film to be etched provided on the substrate to be processed, is any one of a tungsten film, a molybdenum film, an osmium film, an iridium film, a ruthenium film, a rhodium film, a copper film, and a nickel film, and in one or more embodiments, is any one of a tungsten film, a molybdenum film, and a nickel film. In one or more embodiments, from the viewpoint of increasing the complexity and miniaturization of wiring, the metal film in the present disclosure is preferably a metal film containing at least one metal selected from Group 6 transition metals and Group 10 transition metals, and for example, at least one selected from a tungsten film, a molybdenum film, and a nickel film is preferred.

In one or more embodiments, when the substrate to be processed comprises a plurality of metal films, the first film may comprise one of a tungsten film, a molybdenum film, an osmium film, an iridium film, a ruthenium film, a rhodium film, a copper film, and a nickel film, and the second film may comprise one of a titanium nitride film and a tantalum nitride film.
The first film may be of a plurality of types.
In one or more embodiments, when the substrate to be processed includes a plurality of metal films, the substrate includes at least one first film.
In one or more embodiments, the substrate to be processed may not have the second film.
Therefore, in one or more embodiments, the substrate to be processed in the substrate processing method of the present disclosure is a substrate that includes a laminate structure in which metal film layers and insulating layers are alternately stacked, and the metal film layers include one or more types of metal films, and at least any of a tungsten film, a molybdenum film, an osmium film, an iridium film, a ruthenium film, a rhodium film, a copper film, and a nickel film.
In one or more embodiments, substrates to be processed by the substrate processing method of the present disclosure include 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.

[Etching solution composition]
The etching solution composition used in the etching step of the substrate processing method of the present disclosure (hereinafter also referred to as the “etching solution composition of the present disclosure”) contains a mixed acid component, an etching inhibitor, and water, and has a pH of 1 or less.

[Mixed acid component]
The mixed acid component contained in the etching solution composition of the present disclosure comprises phosphoric acid, an organic acid, and nitric acid.

[phosphoric acid]
The amount of phosphoric acid in the etching solution composition of the present disclosure is, from the viewpoint of glossiness, preferably 35% by mass or more, more preferably 40% by mass or more, even more preferably 45% by mass or more, still more preferably 50% by mass or more, and still more preferably 55% by mass or more, and from the viewpoint of glossiness, is preferably 90% by mass or less, more preferably 85% by mass or less, and still more preferably 80% by mass or less.

[Organic acid]
Examples of organic acids contained in the etching solution composition of the present disclosure 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. From the viewpoint of suppressing a decrease in gloss, the organic acid is preferably a monovalent organic acid having 1 to 10 carbon atoms, more preferably a monovalent carboxylic acid having 1 to 10 carbon atoms, and even more preferably acetic acid. One type of organic acid may be used alone, or two or more types may be used in combination.
The amount of the organic acid in the etching solution composition of the present disclosure is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more, from the viewpoint of etching inhibition rate, and is preferably 45% by mass or less, more preferably 40% by mass or less, and even more preferably 35% by mass or less, from the viewpoint of etching inhibition rate. When two or more organic acids are used in combination, the amount of the organic acid is the total amount thereof.

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

For example, when the organic acid is acetic acid, in one or more embodiments, the amount of phosphoric acid in the mixed acid component consisting of phosphoric acid, acetic acid, and nitric acid is preferably 50% by mass or more and 95% by mass or less, more preferably 60% by mass or more and 93% by mass or less, and even more preferably 65% by mass or more and 90% by mass or less, from the viewpoint of gloss. From the same viewpoint, in one or more other embodiments, the amount of phosphoric acid in the mixed acid is preferably 45% by mass or more and 95% by mass or less, more preferably 50% by mass or more and 93% by mass or less, and even more preferably 55% by mass or more and 90% by mass or less. From the same viewpoint, the amount of acetic acid in the mixed acid is preferably 2% by mass or more and 80% by mass or less, more preferably 3% by mass or more and 70% by mass or less, and even more preferably 5% by mass or more and 60% by mass or less. From the same viewpoint, the amount of nitric acid in the mixed acid is preferably 0.5% by mass or more and 20% by mass or less, more preferably 1% by mass or more and 15% by mass or less, and even more preferably 1.5% by mass or more and 10% by mass or less. The mass ratio of phosphoric acid, acetic acid, and nitric acid (phosphoric acid/acetic acid/nitric acid) can be set as appropriate, for example, 88/8/4.

From the viewpoint of suppressing a decrease in gloss, the total amount of mixed acid in the etching solution composition of the present disclosure is preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more. From the 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. From the same viewpoint, the total amount of mixed acid in the etching solution composition of the present disclosure is preferably 70% by mass or more and 98% by mass or less, more preferably 75% by mass or more and 95% by mass or less, and even more preferably 80% by mass or more and 90% by mass or less.

[Etching inhibitor]
The etching inhibitor in the present disclosure may be an organic amine compound selected from polyalkyleneimine, a polymer having a constitutional unit derived from diallylamine, and polyalkylenepolyamine. Among these, in one or more embodiments, at least one of polyalkyleneimine and polyalkylenepolyamine is preferred as the etching inhibitor from the viewpoint of suppressing a decrease in gloss.
Examples of the polyalkyleneimine include polyethyleneimine.
Examples of the polymer containing a constitutional unit derived from diallylamine include diallylamine/sulfur dioxide copolymers.
Examples of polyalkylene polyamines include triethylenetetramine and diethylenetriamine.
The etching inhibitor contained in the etching liquid composition of the present disclosure may be used alone or in combination of two or more.

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 suppressing a decrease in gloss, and from the viewpoint of viscosity, it 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, 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 polymer containing a constitutional 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, and even more preferably 4,000 or more from the viewpoint of suppressing a decrease in gloss, and from the same viewpoint, is preferably 50,000 or less, more preferably 10,000 or less, and even more preferably 7,000 or less. From the viewpoint of viscosity, the weight-average molecular weight of the etching inhibitor is preferably 2,000 or more and 50,000 or less, more preferably 3,000 or more and 10,000 or less, and even more preferably 4,000 or more and 7,000 or less.
When the etching inhibitor is a polyalkylene polyamine, the number average molecular weight or 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 viewpoint of suppressing a decrease in gloss, 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 number average molecular weight or 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, 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 Na ₂ SO ₄ , 1% CH ₃ COOH/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)
<GPC Conditions (Polymer Containing Diallylamine-Derived Constitutional Units)>
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 Na ₂ SO ₄ , 1% CH ₃ COOH/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)

From the viewpoint of suppressing a decrease in gloss, the etching inhibitor in the present disclosure preferably has an etching inhibition rate of 20% or more, more preferably 30% or more, even more preferably 40% or more, even more preferably 50% or more, even more preferably 60% or more, even more preferably 70% or more, even more preferably 80% or more, even more preferably 85% or more, even more preferably 90% or more, and even more preferably 93% or more.

In the present disclosure, the etching inhibition rate refers to the rate of decrease in the etching rate when an etching inhibitor is used relative to the etching rate when no etching inhibitor is used. In one or more embodiments, the etching inhibition rate can be calculated by subtracting the relative etching rate A of the etching solution composition from 100, where A is the etching rate of a mixed acid aqueous solution comprising phosphoric acid, acetic acid, nitric acid, and water, the mass ratio of the phosphoric acid, acetic acid, and nitric acid being the same as the mass ratio of the phosphoric acid, acetic acid, and nitric acid in the etching solution composition, and the total mass of the phosphoric acid, acetic acid, and nitric acid being 85% by mass. The mass ratio of the amounts of each component in the mixed acid aqueous solution can be set as appropriate. In one or more embodiments, the etching inhibition rate can be measured by adjusting the operating conditions, such as temperature and time, to the etching conditions. The measurement conditions for the etching inhibition rate vary depending on the metal contained in the layer to be etched. In one or more embodiments, preferred ranges of temperature and time for 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. 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 40°C for 10 minutes if the metal plate used for measurement is a molybdenum plate or nickel plate. The shape of the metal plate used for measurement can be, for example, a plate-like body measuring 2 cm in length, 2 cm in width, and 0.1 mm in thickness. Specifically, the etching inhibition rate can be determined by the method described in the Examples.

In one or more embodiments, the etching inhibitor of the present disclosure is preferably an organic amine compound with an etching inhibition rate of 20% or more, from the viewpoint of suppressing a decrease in gloss.

In one or more embodiments, the etching inhibitor of the present disclosure is preferably an organic amine compound that can adjust the zeta potential of the surface of the metal film to be etched to greater than 0 mV and less than or equal to 50 mV, from the viewpoint of suppressing a decrease in gloss. 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 greater, and even more preferably 20 mV or greater. The zeta potential of the metal surface may also be 50 mV or less, 40 mV or less, or 35 mV or less.

The amount of etching inhibitor in the etching solution composition of the present disclosure is preferably 0.05% by mass or more, more preferably 0.07% by mass or more, and even more preferably 0.09% by mass or more, from the viewpoints of suppressing a decrease in gloss and suppressing the etching rate. From the viewpoint of good handleability, it is preferably less than 5% by mass, more preferably 3% by mass or less, and even more preferably 2% by mass or less. More specifically, from the viewpoints of suppressing a decrease in gloss, suppressing the etching rate, and good handleability, the amount of etching inhibitor in the etching solution composition of the present disclosure is preferably 0.05% by mass or more but less than 5% by mass, more preferably 0.07% by mass or more but 3% by mass or less, and even more preferably 0.09% by mass or more but 2% by mass or less. When two or more etching inhibitors are used in combination, the amount of etching inhibitor is the total amount of the combined amounts.

[Mass ratio: mixed acid/etching inhibitor]
The mass ratio of the amount of the mixed acid component to the amount of the etching inhibitor in the etching solution composition of the present disclosure (mixed acid/etching inhibitor) is, from the viewpoint of good handleability, 20 or more, preferably 100 or more, and more preferably 150 or more, and, from the viewpoints of suppressing a decrease in glossiness and suppressing an etching rate, is 900 or less, preferably 500 or less, and more preferably 300 or less. The mass ratio (mixed acid/etching inhibitor) in the etching solution composition of the present disclosure is, from the viewpoints of suppressing a decrease in glossiness, suppressing an etching rate, and good handleability, 20 or more and 900 or less, preferably 100 or more and 500 or less, and more preferably 150 or more and 300 or less.

[water]
In one or more embodiments, the etching solution composition of the present disclosure contains water. Examples of water contained in the etching solution of the present disclosure include distilled water, ion-exchanged water, pure water, and ultrapure water.

From the viewpoint of suppressing a decrease in gloss, 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, and even more preferably 7% by mass or more. From the same viewpoint, the amount of water in the etching solution composition of the present disclosure is preferably 30% by mass or less, 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 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.

[Other ingredients]
The etching solution composition of the present disclosure may further contain other components within the scope that does not impair the effects of the present disclosure, such as inorganic acids other than phosphoric acid and nitric acid, chelating agents, surfactants, solubilizing agents, preservatives, rust inhibitors, disinfectants, 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, in one or more embodiments, "does not contain hydrogen peroxide" includes not containing hydrogen peroxide, not substantially containing hydrogen peroxide, or not containing an amount of hydrogen peroxide that would affect the etching results. The amount of hydrogen peroxide in the etching solution composition of the present disclosure is not particularly limited, but is preferably 3% by mass or less, more preferably 1% by mass or less, even more preferably 0.1% by mass or less, even more preferably 0.01% by mass or less, and even more preferably 0% by mass.

In one aspect, the present disclosure provides an etching solution composition for use in an etching step in a substrate processing method of the present disclosure, comprising:
The etching inhibitor includes a mixed acid component, an etching inhibitor, and water.
The pH is 1 or less,
the mixed acid component comprises phosphoric acid, an organic acid, and nitric acid;
the etching inhibitor is at least one organic amine compound selected from polyalkyleneimine, a polymer having a constitutional unit derived from diallylamine, and polyalkylenepolyamine;
The etching solution composition relates to a mass ratio of the mixed acid component to the etching inhibitor in the etching solution composition of 20 or more and 900 or less.

[Method of manufacturing the etching solution composition]
In one or more embodiments, the etching solution composition of the present disclosure is obtained by blending phosphoric acid, an organic acid, nitric acid, an etching inhibitor, water, and, if desired, the optional components described above, by a known method.
In the present disclosure, "blending at least phosphoric acid, an organic acid, nitric acid, an etching inhibitor, and water" means, in one or more embodiments, simultaneously or sequentially mixing phosphoric acid, an organic acid, nitric acid, an etching inhibitor, water, and, if necessary, the optional components described above. The order of mixing is not particularly limited. The blending can be performed using a mixer such as a propeller-type agitator, a pump-based liquid circulation agitator, a homomixer, a homogenizer, an ultrasonic disperser, or a wet ball mill.
The preferred amount of each component may be the same as the amount of each component in the etching liquid composition of the present disclosure described above.

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

In one or more embodiments, the etching solution composition of the present disclosure can be obtained by blending a mixed acid composition containing phosphoric acid, an organic acid, and nitric acid with an etching inhibitor. Accordingly, in one or more embodiments, the substrate processing method of the present disclosure can include blending a mixed acid composition containing a mixed acid component consisting of phosphoric acid, an organic acid, and nitric acid with an etching inhibitor to obtain the etching solution composition. In one aspect, the present disclosure also relates to a method for producing the etching solution composition of the present disclosure, the method including blending a mixed acid composition containing a mixed acid component consisting of phosphoric acid, an organic acid, and nitric acid with an etching inhibitor to obtain the etching solution composition of the present disclosure. The mixed acid composition may contain water and, if necessary, the other components described above. The blending of the mixed acid composition and the etching inhibitor can be performed using the mixer described above.
The amount of phosphoric acid in the mixed acid composition is preferably 25% by mass or more and 90% by mass or less, more preferably 30% by mass or more and 85% by mass or less, and even more preferably 35% by mass or more and 80% by mass or less, from the viewpoint of suppressing a decrease in gloss.
From the viewpoint of suppressing a decrease in gloss, the amount of the organic acid in the mixed acid composition is preferably 10% by mass or more and 70% by mass or less, more preferably 15% by mass or more and 65% by mass or less, and even more preferably 20% by mass or more and 60% by mass or less.
The amount of nitric acid in the mixed acid composition is preferably 0.5% by mass or more and 20% by mass or less, more preferably 1% by mass or more and 15% by mass or less, and even more preferably 2% by mass or more and 10% by mass or less, from the viewpoint of suppressing a decrease in gloss.
The mass ratio of phosphoric acid, organic acid, and nitric acid in the mixed acid composition (phosphoric acid/organic acid/nitric acid) is preferably 25 to 90/8 to 70/0.5 to 20, more preferably 30 to 85/8 to 65/1 to 15, and even more preferably 35 to 80/8 to 60/2 to 10, from the viewpoint of suppressing a decrease in gloss.
The amount of water in the mixed acid composition is preferably 1% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 25% by mass or less, and even more preferably 5% by mass or more and 20% by mass or less, from the viewpoint of suppressing a decrease in gloss.
In one or more embodiments, the mixed acid composition is used in the substrate processing method of the present disclosure or the method for producing the etching solution composition of the present disclosure. Accordingly, in one aspect, the present disclosure relates to a mixed acid composition for use in the substrate processing method of the present disclosure or the method for producing the etching solution composition of the present disclosure, the mixed acid composition comprising a mixed acid component consisting of phosphoric acid, an organic acid, and nitric acid.

Embodiments of the etching solution composition disclosed herein may be so-called one-component types, in which all components are supplied to the market in a pre-mixed state, or so-called two-component types, in which components are mixed at the time of use. Examples of two-component etching solution compositions include those in which water is separated into a first and second component, and phosphoric acid, an organic acid, nitric acid, and an etching inhibitor are contained in either or both of the first and second components, and the first and second components are mixed at the time of use. The first and second components may each contain the optional components described above, as necessary.

From the viewpoint of suppressing a decrease in gloss, 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 preferably -5 or more, more preferably -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, it can be measured by the method described in the examples.

The etching solution composition of the present disclosure may be stored and supplied in a concentrated state as long as its stability is not impaired. This is preferable because it reduces production and transportation costs. This concentrated solution can then be diluted appropriately with water or an aqueous acid solution as needed 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-component etching solution) that contains a first liquid and a second liquid in a mutually unmixed state, and in which phosphoric acid, an organic acid, nitric acid, and an etching inhibitor are contained in either one or both of the first and second liquids, and the first and second liquids are mixed at the time of use. After the first and second liquids are mixed, they may be diluted with water or an aqueous acid solution as needed. The first or second liquid may contain all or a portion of the water used to prepare the etching solution. The first and second liquids may each contain the optional components described above as needed.
An example of the kit of the present disclosure is a kit (two-component etching solution) that contains a solution containing an etching inhibitor (Liquid 1a) and a mixed acid composition containing phosphoric acid, an organic acid, and nitric acid (Liquid 2a) in a mutually unmixed state, and that is mixed at the time of use. After Liquid 1a and Liquid 2a are mixed, they may be diluted with water or an aqueous acid solution as needed. Liquid 1a or Liquid 2a may contain all or a portion of the water used to prepare the etching solution. The acid contained in Liquid 2a may be all or a portion of the acid used to prepare the etching solution. Liquid 1a may contain an acid. Liquid 1a and Liquid 2a may each contain the optional components described above as needed.
The kit of the present disclosure can provide an etching solution composition that can be used in the substrate processing method of the present disclosure.

[Etching process]
The etching step in the substrate processing method of the present disclosure is a step of etching the exposed metal film portion of the substrate to be processed described above with the etching solution composition of the present disclosure.

The etching solution composition of the present disclosure used in the etching process of the present disclosure has an etching rate controlled to a low level by the etching inhibitor, making it suitable for substrate processing including etching processes that require a low etching rate.

In the etching process of the present disclosure, examples of etching methods 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 suppressing a decrease in glossiness, 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 disclosed herein, the etching time can be set, for example, to between 1 minute and 180 minutes.

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

In one or more embodiments, the substrate processing method and the etching solution composition of the present disclosure can be used to etch substrates in the manufacturing process of electronic devices, particularly semiconductor wafers.
In one or more embodiments, the substrate processing method and the etching solution composition of the present disclosure can be suitably used for producing at least one type of substrate selected from 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.
According to one or more embodiments of the substrate processing method of the present disclosure, a decrease in glossiness of a metal film due to etching is suppressed, and productivity and yield can be improved.
According to one or more embodiments of the substrate processing method of the present disclosure, the etching rate is suppressed, and productivity and yield can be improved.
In one or more embodiments, the substrate processing method and the etching solution composition 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 substrate processing method and the etching solution composition of the present disclosure can be suitably used for producing a pattern having a three-dimensional structure, thereby obtaining an advanced device such as a large-capacity memory.
The substrate processing method and the etching solution composition of the present disclosure can be used in, for example, an etching method such as that disclosed in JP 2020-145412 A (Patent Document 2).

The present disclosure will be explained in detail below using examples, but the present disclosure is not limited to these examples in any way.

1. Preparation of Etching Solution (Examples 1 to 6, Comparative Examples 1 to 3)
The etching inhibitors shown in Table 1, mixed acids (phosphoric acid/acetic acid/nitric acid, mass ratio: 88/8/4), and water were blended to obtain etching solutions (pH: -1) of Examples 1 to 6 and Comparative Examples 1 to 3. The mass ratios of the mixed acids were calculated on a mass basis.
The amount of each component (mass %, active content) in the prepared etching solution is shown in Table 1. The amount of water in Table 1 also includes the amount of water contained in the acid aqueous solution, 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 Industries, Ltd., concentration 70%]
(organic acid)
Acetic acid [Fujifilm Wako Pure Chemical Industries, Ltd., concentration 100%]
(etching inhibitor)
Polyethyleneimine (number average molecular weight 1,800, "Epomin SP-018" manufactured by Nippon Shokubai Co., Ltd.)
Triethylenetetramine [molecular weight 146, "TETA" manufactured by Tosoh Corporation]
(water)
Water [ultrapure water produced using a continuous pure water production system (Pure Conti PC-2000VRL) and subsystem (Macace KC-05H) manufactured by Kurita Water Industries Ltd.]

2. Method for Measuring pH of Etching Solution The pH value of the etching solution was measured using a pH meter (manufactured by DKK-TOA Corporation), and was the value measured one minute after immersing the electrode of the pH meter in the etching solution at 25°C.

3. Method for Measuring Viscosity of Etching Solution The viscosity of the etching solution was measured using the following viscometer under the following conditions.
Device name: TVB-10 viscometer (with thermostatic bath) manufactured by Toki Sangyo Co., Ltd.
Rotor: Spindle No. M1, Cord No. 20
Rotation speed: 100 rpm, viscosity value measured after 60 seconds Measurement temperature: 25°C

4. Evaluation of etching solution [Evaluation of etching rate and etching inhibition rate of tungsten plate]
A tungsten plate having a length of 2 cm, a width of 2 cm and a thickness of 0.1 mm, the weight of which had been measured in advance, was immersed in the etching solution prepared for each composition (Examples 1 to 6 and Comparative Examples 1 to 3), and the tungsten plate was etched at 90°C for 120 minutes. After washing with water, the tungsten plate was again weighed, and the difference between the weights was taken as the amount of etching. A precision balance was used to measure the weight.
The etching rate was then calculated using the following formula:
Etching rate (mg/min) = etching amount (mg) / etching time (min)
The results of the etching rate of the tungsten plate are shown in Table 1. The etching rate of the tungsten plate in Comparative Example 1 was taken as 100, and the relative rate of each example was subtracted from 100 to obtain the etching inhibition rate (%), which is also shown in Table 1.
[Evaluation of etching rate and etching inhibition rate of nickel plate]
The nickel plate was etched in the same manner as the tungsten etching method described above, except that a nickel plate measuring 2 cm in length, 2 cm in width, and 0.1 mm in thickness was used instead of the tungsten plate, and the etching conditions were changed to an etching temperature of 40°C and an etching time of 10 minutes, and the etching rate of the nickel plate was measured. The results of the etching rate of the nickel plate are shown in Table 1. In addition, the etching inhibition rate (%) was calculated by subtracting the relative rate of each example, where the etching rate of the nickel plate in Comparative Example 1 was taken as 100, and this value is shown in Table 1.

[Evaluation of Glossiness]
The appearance of the tungsten plate and nickel plate after etching with each etching solution was visually inspected, and the gloss after etching was evaluated based on the following criteria. The results are shown in Table 1.
<Evaluation criteria>
5: The entire plate is in a mirror-like state. 4: Most of the plate is in a mirror-like state, but some corrosion marks can be seen. 3: Half of the plate is in a mirror-like state, but the other half shows corrosion marks. 2: Most of the plate shows corrosion marks. 1: The entire plate is cloudy and there is no mirror-like state at all.

[Evaluation of handling]
The handling properties of each etching solution were evaluated based on the following criteria, and the results are shown in Table 1.
<Evaluation criteria>
◯: Easy to handle △: High viscosity limits the equipment such as pumps that can be used

As shown in Table 1, the etching solutions of Examples 1 to 6, which contain an etching inhibitor, had a slower etching rate for tungsten plate and nickel plate, suppressed the loss of gloss due to etching, and were easier to handle than the etching solutions of Comparative Examples 1 to 3, which do not contain an etching inhibitor.

The substrate processing method disclosed herein is useful for manufacturing, for example, 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 (8)

A substrate processing method including an etching step of etching an exposed portion of a metal film on a substrate having a metal film with an etching solution composition,
the metal film is any one of a tungsten film, a molybdenum film, an osmium film, an iridium film, a ruthenium film, a rhodium film, a copper film, and a nickel film;
the etching solution composition contains a mixed acid component, an etching inhibitor, and water, and has a pH of 1 or less;
the mixed acid component comprises phosphoric acid, an organic acid, and nitric acid;
the etching inhibitor is at least one organic amine compound selected from polyalkyleneimine, a polymer having a constitutional unit derived from diallylamine, and polyalkylenepolyamine;
the mass ratio of the mixed acid component to the etching inhibitor in the etching solution composition is 20 or more and 900 or less. The substrate processing method according to claim 1, comprising the step of obtaining the etching solution composition by blending a mixed acid composition containing a mixed acid component consisting of phosphoric acid, an organic acid, and nitric acid with an etching inhibitor. the substrate includes a laminate structure in which metal film layers and insulating layers are alternately and repeatedly stacked;
2. The substrate processing method according to claim 1, wherein the metal film layer includes one or more types of metal films, and includes at least one of a tungsten film, a molybdenum film, an osmium film, an iridium film, a ruthenium film, a rhodium film, a copper film, and a nickel film. The substrate processing method of claim 1 , wherein the etchant composition does not contain hydrogen peroxide. 2. The substrate processing method according to claim 1, wherein the substrate is at least one type of substrate selected from the group consisting of 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. An etching solution composition for use in the etching step of the substrate processing method according to claim 1 , comprising:
The etching inhibitor includes a mixed acid component, an etching inhibitor, and water.
The pH is 1 or less,
the mixed acid component comprises phosphoric acid, an organic acid, and nitric acid;
the etching inhibitor is at least one organic amine compound selected from polyalkyleneimine, a polymer having a constitutional unit derived from diallylamine, and polyalkylenepolyamine;
The etching solution composition, wherein the mass ratio of the mixed acid component to the etching inhibitor in the etching solution composition is 20 or more and 900 or less. 7. A method for producing the etching solution composition according to claim 6, comprising:
A method for producing an etching solution composition, comprising the step of blending a mixed acid composition containing a mixed acid component consisting of phosphoric acid, an organic acid, and nitric acid with an etching inhibitor to obtain the etching solution composition. A mixed acid composition for use in the substrate processing method according to any one of claims 2 to 5 or the method for producing the etching solution composition according to claim 7, comprising:
A mixed acid composition comprising a mixed acid component consisting of phosphoric acid, an organic acid, and nitric acid.