The chemical solution of the present embodiment may or may not contain an anticorrosive agent. The chemical solution of the present embodiment may not contain one or more selected from the group consisting of nitrogen-containing heterocyclic compounds, ascorbic acids, catechols, sugars, and polycarboxylic acids, and may not contain one or more of the compounds described above as a specific example of the anticorrosive agent.

<<Buffer>>

The chemical solution of the present embodiment may contain a buffer. A buffer is a compound that has the effect of suppressing changes in the pH of a solution.

The buffer is not particularly limited other than being a compound that has a pH buffering ability.

Examples of buffers include weak acids and Good's buffers. Examples of weak acids include acetic acid, citric acid, phosphoric acid, phosphonic acid, boric acid, oxalic acid, malonic acid, succinic acid, glutamic acid, and the like. Examples of Good's buffers include 2-cyclohexylaminoethanesulfonic acid (CHES), 3-cyclohexylaminopropanesulfonic acid (CAPS), N-tris(hydroxymethyl)methyl-3-aminopropanesulfonic acid (TAPS), 4-(cyclohexylamino)-1-butanesulfonic acid (CABS), tricine, bicine, 2-morpholinoethanesulfonic acid-monohydrate (MES), bis(2-hydroxyethyl)aminotris(hydroxymethyl)methane (Bis-Tris), N-(2-acetamido)iminodiacetic acid (ADA), piperazine-1,4-bis(2-ethanesulfonic acid) (PIPES), N-(2-acetamido)-2-aminoethanesulfonic acid (ACES), 2-hydroxy-3-morpholinopropanesulfonic acid (MOPSO), N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid (BES), 3-morpholinopropanesulfonic acid (MOPS), N-tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid (TES), 2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid (HEPES), 3-[N-tris(hydroxymethyl)methyl amino]-2-hydroxypropanesulfonic acid (TAPSO), piperazine-1,4-bis(2-hydroxypropanesulfonic, acid) (POPSO), 4-(2-hydroxyethyl)piperazine-1-(2-hydroxypropane-3-sulfonic acid) (HEPSO), 4-(2-hydroxyethyl)-1-piperazinepropanesulfonic acid (EPPS), and the like.

One type of buffer may be used alone, or two or more types may be used in combination.

In a case where the chemical solution of the present embodiment contains a buffer, the content of the buffer is not particularly limited and examples thereof include 0.001% by mass to 10% by mass with respect to the total mass of the chemical solution, preferably 0.005% by mass to 8% by mass, more preferably 0.01% by mass to 6% by mass, particularly preferably 0.05% by mass to 4% by mass or 0.1% by mass to 3% by mass.

The chemical solution of the present embodiment may or may not contain a buffer. The chemical solution of the present embodiment may or may not contain one or more of the compounds described above as specific examples of the buffer.

The chemical solution of the present embodiment may include a slurry (metal oxide particles) such as used in, for example, a Chemical Mechanical Polishing (CMP) process, or may not include a slurry (metal oxide particles), but preferably not.

Examples of polishing agents include metal oxide particles such as alumina, silica, titania, ceria, and zirconia. The chemical solution of the present embodiment preferably does not include these metal oxide particles.

<<pH>>

The pH of the chemical solution of the present embodiment is not particularly limited. The pH of the chemical solution of the present embodiment is, for example, 5.0 or less. The pH may be 3.0 or less, 2.5 or less, 2.0 or less, 1.5 or less, or 1.0 or less. The pH value is a value measured by a pH meter under conditions of room temperature (25° C.) and normal pressure (1 atmospheric pressure). The pH of the chemical solution of the present embodiment may be less than 1.0. It is possible to calculate a degree of acidity that is less than 1.0 in the chemical solution using Hammett's acidity function, for example.

<<Specific Gravity>>

The specific gravity of the chemical solution of the present embodiment is not particularly limited. The specific gravity of the chemical solution of the present embodiment is 0.90 to 1.60. The specific gravity value is a value measured under conditions of room temperature (25° C.) and normal pressure (1 atmospheric pressure). The specific gravity of the chemical solution of the present embodiment may be, for example, 1.55 or less, or 1.50 or less. The specific gravity of the chemical solution of the present embodiment may be, for example, 0.95 or more or 1.00 or more.

<<Impurities and the Like>>

The chemical solution of the present embodiment may include, for example, impurities derived from organic substances (organic impurities). The total content of the organic impurities in the chemical solution of the present embodiment is preferably 5,000 mass ppm or less. The lower limit of the content of the organic impurities is preferably as low as possible, for example, 1 mass ppq or more. The total content of organic impurities is, for example, 1 ppq by mass to 5,000 ppm by mass.

The chemical solution of the present embodiment may include, for example, objects to be counted, which are of a size which is countable using a light scattering particle-in-liquid counter. The size of the objects to be counted is, for example, 0.04 μm or more. The number of objects to be counted in the chemical solution of the present embodiment is, for example, 1,000 or less per 1 mL of the chemical solution and the lower limit value is, for example, 1 or more. It is considered that the effect of suppressing metal corrosion by the chemical solution is improved due to the number of objects to be counted in the chemical solution being within the above range. The size of the objects to be counted may be a size detectable by a light scattering particle-in-liquid counter and may be, for example, 0.01 μm or more.

The organic impurities and/or the objects to be counted may be added to the chemical solution, or may be inevitably mixed into the chemical solution during the manufacturing steps of the chemical solution. Examples of cases where organic impurities are inevitably mixed in the manufacturing steps of chemical solutions include cases where organic impurities are included in raw materials (for example, organic solvents) used in the manufacturing of chemical solutions, cases where organic impurities are mixed in from the external environment during the manufacturing steps of chemical solutions (for example, contamination), and the like, without being limited thereto.

In a case of adding objects to be counted to a chemical solution, the abundance ratio may be adjusted for each specific size, taking into consideration the surface roughness and the like of the object to be cleaned.

The method for storing the chemical solution of the present embodiment is not particularly limited and it is also possible to use storage containers known in the related art. In order to ensure the stability of the chemical solution, the porosity in the container when storing in the container and/or the type of gas filling the void portions may be appropriately set. For example, the porosity in the storage container is approximately 0.01 to 30% by volume.

When using the chemical solution of the present embodiment, a diluted solution may be obtained by diluting the chemical solution 2 to 2000 times and then the substrate may be treated using the diluted solution. It is possible to dilute the chemical solution with water, for example.

The content of each component included in the chemical solution of the present embodiment may be a measurement value measured by a measuring device. It is possible to appropriately select a known measuring device depending on the type of component. In a case where the content of the target component is less than the detection limit, the measurement may be performed after appropriately concentrating the chemical solution.

Each component included in the chemical solution of the present embodiment may be purified as appropriate before being blended into the chemical solution. As the purification method, it is possible to use known methods depending on the type of component.

The chemical solution of the present embodiment is used to remove precious metals and a substrate including precious metals is set as the treating target. The substrate is not particularly limited other than including a precious metal and examples thereof include a substrate having a precious metal-containing layer (precious metal-containing film). The substrates are not particularly limited and examples thereof include various substrates such as semiconductor wafers, glass substrates for photomasks, glass substrates for liquid crystal displays, glass substrates for plasma displays, substrates for Field Emission Displays (FED), substrates for optical discs, substrates for magnetic disks, and substrates for magneto-optical discs. The substrate is preferably a substrate used for producing semiconductor devices. In addition to the ruthenium-containing layer and the base material of the substrate, the substrate may have, as appropriate, various layers and structures, for example, metal wiring, gate structures, source structures, drain structures, insulating layers, ferromagnetic layers, nonmagnetic layers, and the like. In addition, the uppermost layer on the device surface of the substrate may not be a ruthenium-containing layer and, for example, an intermediate layer of a multilayer structure may be the ruthenium-containing layer.

The size, thickness, shape, layer structure, and the like of the substrate are not particularly limited and are appropriately selectable depending on the purpose.

The precious metal-containing layer is preferably a layer containing a precious metal and more preferably a precious metal film. The thickness of the precious metal-containing layer on the substrate is not particularly limited and is appropriately selectable depending on the purpose. The thickness of the precious metal-containing layer is, for example, in the range of 0.1 to 500 nm, 0.1 to 30) nm, 0.5 to 200 nm, 0.5 to 100 nm, 1 to 100 nm, and 1 to 50 nm.

Precious metals refer to gold (Au), silver (Ag), platinum (Pt), palladium (Pd), rhodium (Rh), iridium (It), ruthenium (Ru), osmium (Os), and rhenium (Re). As the precious metal, ruthenium, iridium, or platinum is preferable and ruthenium or platinum is more preferable. The precious metal may be a simple substance of a precious metal, an alloy of precious metals, or a precious metal compound. Examples of precious metal compounds include precious metal oxides, precious metal nitrides, precious metal oxynitrides, and the like. The content of the precious metal in the precious metal-containing layer is preferably 20% by mass or more with respect to the total mass of the composition forming the precious metal-containing layer, more preferably 50% by mass or more, even more preferably 80% by mass or more, and may be 100% by mass, it is possible to form the precious metal-containing layer by a known method, for example, it is possible to use a chemical vapor deposition (CVD) method, an atomic layer deposition (ALD) method, a physical vapor deposition (PVD) method, or the like.

It is possible to suitably use the chemical solution of the present embodiment, for example, for removing a precious metal-containing film on the outer edge of a substrate, removing precious metal-containing substances adhering to the back surface of a substrate, and the like.

<<Removal of Precious Metal-Containing Film on Outer Edge of Substrate>>

The chemical solution of the present embodiment may be used to remove a precious metal-containing film on the outer edge of a substrate on which the precious metal-containing film is arranged. The chemical solution of the present embodiment may be used, for example, to remove a precious metal-containing film positioned at the outer edge in a laminate having a substrate and a precious metal-containing film arranged on the main surface of one side of the substrate.

The precious metal-containing film preferably contains at least one selected the group consisting of a simple substance of a precious metal, a precious metal alloy, a precious metal oxide, a precious metal nitride, and a precious metal oxynitride.

Although the specific method is not particularly limited, examples thereof include a method of supplying the chemical solution from a nozzle such that the chemical solution of the present embodiment comes into contact only with the precious metal-containing film on the outer edge of the substrate. The treatment time (contact time between the chemical solution and the wiring substrate) is not particularly limited and examples thereof include 0.01 to 30 minutes, 0.1 to 20 minutes, 0.1 to 10 minutes, 0.15 to 5 minutes, or the like. The treatment temperature is not particularly limited and examples thereof include 15 to 75° C. 15 to 65° C. 15 to 55° C., 15 to 50° C., or the like.

<<Removal of Precious Metal-Containing Substances Adhering to Back Surface of Substrate>>

The chemical solution of the present embodiment may be used to remove precious metal-containing substances adhering to the back surface of a substrate on which a precious metal-containing film is arranged. When forming a laminate including a substrate and a precious metal-containing film arranged on the main surface of one side of the substrate, the precious metal-containing film is formed by PVD) (for example, sputtering), CVD, or the like. At that time, precious metal-containing substances may adhere to the surface of the substrate on the opposite side (the back surface) to the precious metal-containing film side. The chemical solution of the present embodiment may be used to remove precious metal-containing substances adhering to the back surface of such a laminate.

Although the specific method is not particularly limited, examples thereof include a method in which the chemical solution is discharged such that the chemical solution of the present embodiment comes into contact only with the back surface of the substrate. The suitable ranges for the contact time and the temperature of the chemical solution are the same as described above.

According to the chemical solution of the present embodiment described above, the precious metal removal performance is improved by containing the specific acid component (B) in addition to the cerium-containing oxidizing agent (A) component. Therefore, using the chemical solution of the present embodiment makes it possible to efficiently treat a substrate including a precious metal-containing layer.

(Method for Manufacturing Chemical Solution)

The method for manufacturing a chemical solution according to the second aspect of the present invention includes a step for dissolving the cerium-containing oxidizing agent (A) and the acid component (B) in water (also referred to below as “step (i)”). The chemical solution according to the first aspect is manufactured by the manufacturing method of the present embodiment.

Step (i) is a step for dissolving the cerium-containing oxidizing agent (A) and the acid component (B) in water.

Component (A) and component (B) are dissolved in water to prepare a solution including component (A) and component (B). Examples of the content or added amount of component (A) and component (B) include the contents described under “(Chemical Solution)” described above.

In a case of adding an optional component to the chemical solution in addition to component (A) and component (B), the optional component is also dissolved in the solution described above. Examples of optional components include the components described in the section of “<Other Components>” in “(Chemical Solution)” described above,

The manufacturing method of the present embodiment may include an optional step in addition to step (i) described above. An example of the optional step is a step of filtering the solution obtained in step (i) using a filter. By performing filter filtration, it is possible to reduce fine particles in the chemical solution and to obtain a high-quality chemical solution.

Examples of filters used for filtration include filters with openings of 0.1 nm or more and 2.0 μm or less. The opening of the filter is preferably 0.5 nm or more and more preferably 1.0 mm or more. The opening of the filter is preferably 1.0 μm or less, more preferably 0.5 m or less, even more preferably 0.2 μm or less, and particularly preferably 0.1 μm or less.

(Substrate Treating Method)

A method for treating a substrate according to a third aspect of the present invention includes a step of using the chemical solution according to the first aspect, which is brought into contact with a substrate on which a precious metal is exposed on a surface, to remove at least a part of the precious metal from the substrate.

Examples of the substrate on which a precious metal is exposed on the surface include the same examples described in “<Applications>” in “(Chemical Solution)” described above and a substrate having a precious metal-containing layer is a preferable example. The method for forming the precious metal-containing layer on the substrate is not particularly limited and it is possible to use any known method. Examples of such methods include a PVD method (for example, sputtering), a CVD method, a molecular beam epitaxy (MBE) method, an ALD method, and the like. The raw material for the precious metal-containing layer used when forming the precious metal-containing layer on the substrate is also not particularly limited and is appropriately selectable depending on the film-forming method. As the precious metal, ruthenium, iridium, or platinum is preferable and ruthenium or platinum is more preferable.

The present step is a step for treating a substrate in which a precious metal is exposed on the surface using the chemical solution according to the first aspect described above and includes an operation of bringing the chemical solution into contact with the precious metal exposed on the surface of the substrate. The contact method is not particularly limited and it is possible to use any known contact method. Examples of the contact method include a spray method, a dipping method, a piling method, and the like, without being limited thereto.

In the spray method, for example, the substrate is transported or rotated in a predetermined direction and the chemical solution according to the first aspect is ejected into the space to bring the chemical solution into contact with the substrate. As necessary, the chemical solution may be sprayed while rotating the substrate using a spin coater.

In the dipping method, the substrate is immersed in the chemical solution according to the first aspect and the chemical solution is brought into contact with the substrate.

In the piling method, the chemical solution according to the first aspect is placed on a substrate and the substrate and the chemical solution are brought into contact with each other.

It is possible to appropriately select these methods depending on the structure, material, and the like of the substrate. In the case of the spray method or the piling method, the amount of the chemical solution supplied to the substrate may be any amount with which the surface to be treated on the substrate is sufficiently wetted with the chemical solution.

The purpose of the treatment is not particularly limited and may be, microfabrication of the surface to be treated of the substrate including a precious metal (for example, a precious metal-containing layer on the substrate), may be the removal of precious metal-containing deposits attached to the substrate (for example, a substrate having a precious metal-containing layer), and may be the cleaning of the surface to be treated of the substrate including the precious metal (for example, the precious metal-containing layer on the substrate).

In a case where the purpose of the treatment is microfabrication of the surface to be treated of the substrate including the precious metal, the substrate and the chemical solution are usually brought into contact after covering the locations that are not to be etched with an etching mask.

In a case where the purpose of the treatment is to remove precious metal-containing deposits attached to the substrate, it is possible to remove the precious metal deposits from the substrate by dissolving the precious metal-containing deposits by bringing the chemical solution according to the first aspect into contact with the substrate.

In a case where the purpose of the treatment is to clean the surface to be treated of the substrate including the precious metal, by bringing the chemical solution according to the first aspect into contact with the surface to be treated of the substrate, the surface to be treated is quickly dissolved and impurities such as particles attached to the surface of the substrate are removed from the surface of the substrate in a short time.

Specifically, examples of the purpose of the treatment include removing the precious metal-containing film on the outer edge of the substrate and removing precious metal-containing substances attached to the back surface of the substrate.

The treatment temperature is not particularly limited as long as it is a temperature at which the precious metal dissolves in the chemical solution. The treatment temperature is, for example, 15° C. to 75° C. In all the cases of the spray method, dipping method, and piling method, the removal efficiency is increased by increasing the temperature of the chemical solution; however, it is possible to select the treatment temperature, as appropriate, in consideration of keeping changes in the composition of the chemical solution small and of workability, safety, cost, and the like.

The treatment time may be selected as appropriate depending on the purpose of the treatment, the type and amount of precious metal to be removed (for example, the thickness of the precious metal-containing layer, the amount of precious metal deposits, and the like), and the treatment conditions.

The treating method of the present embodiment may include optional steps in addition to the steps described above. Examples of the optional steps include a step for rinsing the substrate, a step for drying the substrate, and the like.

It is possible to perform the rinsing treatment by bringing the rinsing liquid into contact with the substrate. The contact method is not particularly limited and examples thereof include a method for immersing a substrate in a rinsing liquid in a tank, a method for spraying a rinsing liquid onto the surface of a substrate, a method for allowing a rinsing liquid to flow onto the surface of the substrate, a method freely combining these methods, or the like.

Examples of rinsing liquids include hydrofluoric acid, hydrochloric acid, hydrogen peroxide, ammonia, tetramethylammonium hydroxide (TMAH), choline, a mixed liquid of hydrofluoric acid and hydrogen peroxide (FPM), a mixed liquid (SPM) of sulfuric acid and hydrogen peroxide, a mixed liquid of ammonia water and hydrogen peroxide (APM), a mixed liquid of hydrochloric acid and hydrogen peroxide (HPM), a mixed liquid of nitric acid and hydrogen peroxide (NPM), carbon dioxide water, ozone water, hydrogen water, citric acid aqueous solution, sulfuric acid, ammonia water, isopropyl alcohol, hypochlorous acid aqueous solution, ultrapure water, nitric acid, oxalic acid aqueous solution, acetic acid (including an acetic acid aqueous solution), and the like.

Examples of acidic rinsing liquids include a citric acid aqueous solution (preferably 0.01 to 10% by mass citric acid aqueous solution), hydrofluoric acid (preferably 0.001 to 10% by mass hydrofluoric acid), hydrochloric acid (preferably 0.001 to 1% by mass hydrochloric acid), hydrogen peroxide (preferably a 0.05 to 10% by mass hydrogen peroxide and more preferably a 0.3 to 4.5% by mass hydrogen peroxide), a mixed liquid of hydrofluoric acid and hydrogen peroxide (FPM), a mixed liquid of sulfuric acid and hydrogen peroxide (SPM), a mixed liquid of hydrochloric acid and hydrogen peroxide (HPM), a mixed liquid of nitric acid and hydrogen peroxide (NPM), carbon dioxide water (preferably 10 to 1,000 mass ppm carbon dioxide water), ozone water (preferably 5 to 60 mass ppm ozone water), hydrogen water (preferably 0.5 to 20 mass ppm hydrogen water), sulfuric acid (preferably 1 to 10% by mass sulfuric acid aqueous solution), ammonia water (preferably 0.05 to 6% by mass ammonia water), TMAH aqueous solution (preferably 0.05 to 5% by mass TMAH aqueous solution), choline aqueous solution (preferably 0.05 to 5% by mass choline aqueous solution), nitric acid (preferably 0.001 to 20% by mass nitric acid), oxalic acid aqueous solution (preferably a 0.01 to 10% by mass oxalic acid aqueous solution), acetic acid (preferably a 0.01 to 10% by mass acetic acid aqueous solution, or acetic acid stock solution), and the like.

The preferable conditions for FPM, SPM, APM, HPM, and NPM are the same as above.

Hydrofluoric acid, nitric acid, and hydrochloric acid are intended to be aqueous solutions in which HF, HNO₃, and HCl are each dissolved in water. Ozone water, carbon dioxide water, ammonia water, TMAH aqueous solution, choline aqueous solution, and hydrogen water are intended to be aqueous solutions in which O₃, CO₂, NH₃, methylammonium hydroxide ([(CH₃)₄N]⁺[OH]⁻), choline (trimethyl-2-hydroxyethylammonium hydroxide; [(CH₃)₃N(CH₂)₂OH]⁺[OH]⁻), and H₂are each dissolved in water.

These rinsing liquids may be mixed for use in a range in which the purpose of the rinsing treatment is not impaired. In addition, the rinsing liquid may include an organic solvent.

The treatment time of the rinsing treatment (the contact time between the rinsing liquid and the substrate) is not particularly limited, but is, for example, 5 seconds to 5 minutes. The temperature of the rinsing liquid during the treatment is not particularly limited, but, for example, is generally preferably 16° C. to 60° C. and more preferably 18° C. to 40° C.

According to the substrate treating method of the present embodiment described above, the chemical solution according to the first aspect is used to treat the substrate on which the precious metal is exposed on the surface, thus, it is possible to efficiently remove the precious metal which is the removal target exposed on the substrate.

(Method for Manufacturing Semiconductor Device)

The method for manufacturing a semiconductor device of the present embodiment includes a step for treating a substrate by the substrate treating method according to the third aspect.

It is possible to perform the step for treating the substrate in the same manner as the method described in “(Substrate Treating Method)” above. The substrate is preferably a substrate having a precious metal-containing layer. As the substrate, it is possible to use a substrate commonly used for producing semiconductor devices.

The method for manufacturing a semiconductor device of the present embodiment may include other steps in addition to the treating steps described above. Such other steps are not particularly limited and examples thereof include known steps that are performed when manufacturing semiconductor devices. Examples of such steps include steps for forming various structures such as metal wiring, a gate structure, a source structure, a drain structure, an insulating layer, a ferromagnetic layer, and a nonmagnetic layer (laver formation, etching other than the etching treatment described above, chemical mechanical polishing, reforming, and the like), resist film formation steps, exposure steps, development steps, heat treatment steps, cleaning steps, inspection steps, and the like, without being limited thereto. It is possible to perform these other steps as appropriate before or after the above treating steps, as necessary.

EXAMPLES

A description will be given below of the present invention in more detail using Examples, but the present invention is not limited to these examples.

Examples 1 to 10, Comparative Examples 1 to 6

Each component shown in Table 1 and Table 2 was mixed to prepare a chemical solution for each example.

TABLE 1

Component (A)
Component (B)

Com-
Amount
Com-
Amount

pound
(mol/L)
pound
(mol/L)
Water

Example 1
CAN
0.037
Formic acid
0.037
Remainder