JP7727416B2 - Cobalt etching chemicals - Google Patents

Description

The present invention relates to a chemical solution for cobalt etching and a method for manufacturing an etched substrate using the chemical solution.

2. Description of the Related Art With the miniaturization of semiconductor devices, various studies are underway regarding the interconnects, contact plugs, and interconnect materials that are fabricated within semiconductor devices.
Furthermore, due to the challenges of electromigration and increased resistance caused by miniaturization of wiring, cobalt is being used as a cap layer to cover copper wiring, or the copper wiring itself is being replaced with cobalt wiring. For these reasons, in the manufacturing process of semiconductor devices, regions made of materials other than cobalt are often provided on a semiconductor substrate along with regions made of cobalt.

During the manufacturing process of semiconductor devices, for example, for the purpose of wiring processing, cobalt etching may be performed on a semiconductor substrate that has regions made of cobalt as well as regions made of materials other than cobalt. Known cobalt etching methods include exposing the substrate surface to a halide, plasma, and applying a bias voltage (see Patent Document 1).

JP 2017-063186 A

However, with the method described in Patent Document 1, the difference in etching rate depending on the metal type is small, making it difficult to preferentially etch only cobalt. Furthermore, when etching cobalt in the manufacture of semiconductor devices, it is also desirable to avoid increasing the surface roughness of the etched cobalt.

The present invention was developed in consideration of the above circumstances, and aims to provide a chemical solution that can preferentially etch only cobalt or cobalt alloys while suppressing an increase in surface roughness after etching, and a method for manufacturing an etched substrate using this chemical solution.

The inventors discovered that the above problems can be solved by using a chemical solution containing an amine compound (A), a carboxylic acid (B), a corrosion inhibitor (C), a water-soluble organic solvent (O), and water (W) for etching cobalt or a cobalt alloy, and thus completed the present invention.

A first aspect of the present invention is a chemical solution for cobalt etching, comprising an amine compound (A), a carboxylic acid (B), a corrosion inhibitor (C), a water-soluble organic solvent (O), and water (W).

A second aspect of the present invention is
providing a substrate having a region composed of cobalt or a cobalt alloy on at least a portion of a surface thereof;
a step of contacting a substrate with the chemical solution according to the first aspect to etch at least a part of a surface layer;
1. A method for producing an etched substrate, comprising:

The present invention provides a chemical solution that can preferentially etch only cobalt or cobalt alloys while suppressing an increase in surface roughness after etching, and a method for manufacturing an etched substrate using this chemical solution.

The following describes in detail an embodiment of the present invention, but the present invention is not limited to the following embodiment and can be implemented with appropriate modifications within the scope of the present invention.

<Chemical solution>
The chemical solution is used for cobalt etching, which includes not only etching of cobalt alone but also etching of cobalt alloys or materials containing cobalt alloys.
The metal contained in the cobalt alloy is not particularly limited as long as the desired effect is not impaired. Examples of metals that may be contained in the cobalt alloy include molybdenum, tantalum, titanium, tungsten, iron, aluminum, nickel, niobium, zirconium, and palladium. Examples of cobalt alloys or materials containing them include cobalt-molybdenum, cobalt-tantalum, cobalt-titanium, cobalt-tungsten, cobalt-iron, cobalt-tungsten-phosphorus, cobalt-tungsten-boron, cobalt-chromium, cobalt-chromium-molybdenum, cobalt-niobium-zirconium, cobalt-aluminum, cobalt-nickel, iron-nickel-cobalt, and cobalt-palladium.

The chemical solution essentially contains an amine compound (A), a carboxylic acid (B), a corrosion inhibitor (C), a water-soluble organic solvent (O), and water (W). By using this chemical solution, it is possible to preferentially etch only the cobalt or cobalt alloy while suppressing an increase in surface roughness after etching.

The drug solution may be a one-component composition in which all components are dissolved, or a multi-component composition consisting of two or more components.

Below, we will explain the essential and optional ingredients contained in the medicinal solution.

<Amine Compound (A)>
The amine compound (A) is not particularly limited as long as it is a compound generally recognized as an amine compound by those skilled in the art of chemistry. The amine compound (A) may be an aromatic amine having an aromatic group bonded to a nitrogen atom, an aliphatic amine having only an aliphatic group bonded to a nitrogen atom, or hydroxylamine or a derivative thereof.
The amine compound (A) can also be used as a salt. The salt may be a salt of an amine compound with an inorganic acid or a salt of an amine compound with an organic acid. Examples of inorganic acids include hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid. The amine compound (A) may form a salt with a carboxylic acid (B) described later in the chemical solution.

Specific examples of amine compounds include alkylamines such as ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, tri-n-propylamine, and methyldiethylamine; alkanolamines such as ethanolamine, diethanolamine, triethanolamine, dimethylethanolamine, and methyldiethanolamine; and hydroxylamines or derivatives thereof such as hydroxylamine, O-methylhydroxylamine, O-ethylhydroxylamine, N-methylhydroxylamine, N,N-dimethylhydroxylamine, N,O-dimethylhydroxylamine, N-ethylhydroxylamine, N,N-diethylhydroxylamine, N,O-diethylhydroxylamine, O,N,N-trimethylhydroxylamine, N,N-dicarboxyethylhydroxylamine, and N,N-disulfoethylhydroxylamine.

Of these amine compounds, alkanolamines and hydroxylamines are preferred because they tend to provide a sufficiently high etching rate for cobalt.

The content of the amine compound (A) in the chemical solution is not particularly limited as long as the desired effect is not impaired. The content of the amine compound (A) in the chemical solution is preferably 0.01% by mass or more and 5% by mass or less, more preferably 0.05% by mass or more and 2% by mass or less, and even more preferably 0.1% by mass or more and 1% by mass or less, based on the mass of the chemical solution.
The chemical solution may be a multi-component type (two or more components), as described below. When the chemical solution is a multi-component type, the content of the amine compound (A) in the chemical solution is the ratio of the mass of the amine compound (A) to the total mass of the multiple components.

<Carboxylic Acid (B)>
The chemical solution contains a carboxylic acid (B). The carboxylic acid (B) is not particularly limited as long as it is a compound having a carboxy group. The carboxylic acid (B) may be an aliphatic carboxylic acid or an aromatic carboxylic acid having an aromatic group. The carboxylic acid (B) may be a monocarboxylic acid having one carboxy group or a polycarboxylic acid having two or more carboxy groups. As the carboxylic acid (B), a polycarboxylic acid having two or more carboxy groups is preferred because it can provide a wider pH buffer range. As the polycarboxylic acid, a dicarboxylic acid, a tricarboxylic acid, or a tetracarboxylic acid is preferred.

Specific examples of carboxylic acids (B) include aliphatic monocarboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, isovaleric acid, and lactic acid; aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, maleic acid, malic acid, and tartaric acid; aliphatic tricarboxylic acids such as citric acid; aromatic monocarboxylic acids such as benzoic acid, 1-naphthoic acid, 2-naphthoic acid, p-hydroxybenzoic acid, m-hydroxybenzoic acid, and o-hydroxybenzoic acid (salicylic acid); aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and phthalic acid; aromatic tricarboxylic acids such as trimellitic acid; and aromatic tetracarboxylic acids such as pyromellitic acid. Among these, aliphatic dicarboxylic acids are preferred.

The content of the carboxylic acid (B) in the chemical solution is not particularly limited as long as the desired effect is not impaired. The content of the carboxylic acid (B) in the chemical solution is preferably 0.01% by mass or more and 5% by mass or less, more preferably 0.05% by mass or more and 3% by mass or less, and even more preferably 0.1% by mass or more and 2% by mass or less, relative to the mass of the chemical solution.
The chemical solution may be a multi-component type (two or more components), as described below. When the chemical solution is a multi-component type, the content of the carboxylic acid (B) in the chemical solution is the ratio of the mass of the carboxylic acid (B) to the total mass of the multiple components.

<Corrosion inhibitor (C)>
The chemical solution contains an anticorrosive (C). As the anticorrosive (C), any compound that has been known to have anticorrosive properties against metals can be used without any particular limitation. By including the anticorrosive (C) in the chemical solution, an increase in the surface roughness of the cobalt can be suppressed when etching the cobalt using the chemical solution.

Specific examples of corrosion inhibitors (C) include phenol, catechol, 1,2,4-triazole (TAZ), 5-aminotetrazole (ATA), 5-amino-1,3,4-thiadiazole-2-thiol, 3-amino-1H-1,2,4-triazole, 3,5-diamino-1,2,4-triazole, 3-amino-5-mercapto-1,2,4-triazole, 1-amino-1,2,4-triazole, 1-amino-1,2,3-triazole, 1-amino-5-methyl-1,2,3-triazole, 3-mercapto-1,2,4-triazole, 3-isopropyl-1,2,4-triazole, 2-mercaptobenzothiazole (2-MBT), 1-phenyl-2-tetrazoline-5-thione, 2-mercaptobenzimidazole (2- MBI), 4-methyl-2-phenylimidazole, 2-mercaptothiazoline, 2,4-diamino-6-methyl-1,3,5-triazine, thiazole, imidazole, benzimidazole, triazine, methyltetrazole, bismuthiol I, 1,3-dimethyl-2-imidazolidinone, 1,5-pentamethylenetetrazole, 1-phenyl-5-mercaptotetrazole, diaminomethyltriazine, imidazolinethione, 4-methyl-4H-1,2,4-triazole-3-thiol, 5-amino-1,3,4-thiadiazole-2-thiol, benzothiazole, 2,3,5-trimethylpyrazine, 2-ethyl-3,5-dimethylpyrazine, quinoxaline, acetylpyrrole, pyridazine, and pyrazine, etc.

Benzotriazoles are also preferred as the corrosion inhibitor (C). Examples of benzotriazoles include benzotriazole (BTA), 1-hydroxybenzotriazole, 5-phenylthiolbenzotriazole, 5-chlorobenzotriazole, 4-chlorobenzotriazole, 5-bromobenzotriazole, 4-bromobenzotriazole, 5-fluorobenzotriazole, 4-fluorobenzotriazole, naphthotriazole, tolyltriazole, 5-phenylbenzotriazole, 5-nitrobenzotriazole, 4-nitrobenzotriazole, 3-amino-5-mercapto-1,2,4-triazole, 2-(5-amino-pentyl)benzotriazole, 1-aminobenzotriazole, 5-methyl-1H-benzotriazole, benzotriazole-5-carboxylic acid, 4-methylbenzotriazole, 4-ethylbenzotriazole, 5-ethylbenzotriazole, and 4-propylbenzylbenzotriazole. Examples of suitable benzotriazoles include benzotriazole, 5-propylbenzotriazole, 4-isopropylbenzotriazole, 5-isopropylbenzotriazole, 4-n-butylbenzotriazole, 5-n-butylbenzotriazole, 4-isobutylbenzotriazole, 5-isobutylbenzotriazole, 4-pentylbenzotriazole, 5-pentylbenzotriazole, 4-hexylbenzotriazole, 5-hexylbenzotriazole, 5-methoxybenzotriazole, 5-hydroxybenzotriazole, dihydroxypropylbenzotriazole, 5-t-butylbenzotriazole, 5-(1',1'-dimethylpropyl)benzotriazole, 5-(1',1',3'-trimethylbutyl)benzotriazole, 5-n-octylbenzotriazole, and 5-(1',1',3',3'-tetramethylbutyl)benzotriazole.

The content of the corrosion inhibitor (C) in the chemical solution is not particularly limited as long as the desired effect is not impaired. The preferred range of the content of the corrosion inhibitor (C) in the chemical solution is 0.0001% by mass to 10% by mass, more preferably 0.001% by mass to 5% by mass, and even more preferably 0.01% by mass to 1% by mass, based on the mass of the chemical solution.

<Surfactant (D)>
The chemical solution may contain a surfactant (D). When the chemical solution contains the surfactant (D), an increase in the surface roughness of the cobalt surface during etching of the cobalt can be easily suppressed.

The surfactant (D) is not particularly limited, and any conventionally known surfactant can be used. Anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants can all be used as the surfactant (D).

As the nonionic surfactant, for example, an alkylene oxide adduct of a diol having a carbon-carbon triple bond, or an alkylene oxide adduct of a monool having a carbon-carbon triple bond is preferred.
As the alkylene oxide adduct of a diol having a carbon-carbon triple bond, for example, a nonionic surfactant represented by the following formula (d-1) is preferred.
HO-(R ^d6 -O) _n1 -CR ^d3 R ^d4 -C≡C-CR ^d1 R ^d2 -(O-R ^d5 ) _n2 -OH...(d-1)
In formula (d-1), R ^d1 to R ^d4 each independently represent a linear or branched alkyl group having from 1 to 6 carbon atoms. ^{R d5} and R ^d6 each independently represent a linear or branched alkylene chain having from 2 to 4 carbon atoms. n1 and n2 each independently represent an integer of from 0 to 30.

R ^d1 to R ^d4 are preferably a methyl group, an ethyl group, or an isopropyl group. ^{R d5} and R ^d6 are preferably an ethane-1,2-diyl group (ethylene group), a propane-1,3-diyl group, a propane-1,2-diyl group, or a butane-1,4-diyl group. n1 and n2 are preferably integers of 0 or more and 16 or less.

Specific examples of alkylene oxide adducts of diols having a carbon-carbon triple bond and alkylene oxide adducts of monools having a carbon-carbon triple bond include Olfine EXP4200 manufactured by Nissin Chemical Industry Co., Ltd.; the "Surfynol 104 series" such as Surfynol 104E, Surfynol 104H, Surfynol 104A, Surfynol 104PA, and Surfynol 104PG-50 manufactured by Air Products Co., Ltd.; and the "Surfynol 400 series" such as Surfynol 420, Surfynol 445, Surfynol 465, and Surfynol 485 manufactured by Air Products Co., Ltd. Of these, the "Surfynol 400 series" is preferred.

Furthermore, polyoxyalkylene alkylamines are also preferred as nonionic surfactants. Polyoxyalkylene alkylamines are compounds in which alkylene oxide is added to alkylamines. As polyoxyalkylene alkylamines, compounds represented by the following formula (d-2) are preferred:
H-(O-R ^d9 ) _n4 -NR ^d7- (R ^d8 -O) _n3 -H...(d-2)

In formula (d-2), R ^d7 represents an aliphatic hydrocarbon group having 8 to 22 carbon atoms, which may have a branch or an unsaturated bond. R ^d8 and R ^d9 each independently represent an ethane-1,2-diyl group (ethylene group) or a propane-1,2-diyl group (propylene group). n3 and n4 represent the average number of moles of ethylene oxide or propylene oxide added, respectively. n3 and n4 are each a number of 0 or greater, and the sum of n3 and n4 is 1 or greater.

The aliphatic hydrocarbon group represented by R ^d7 preferably has 10 or more and 22 or less carbon atoms, more preferably has 12 or more and 20 or less carbon atoms, and even more preferably has 14 or more and 20 or less carbon atoms.

The polyoxyalkylene alkylamine represented by formula (d-2) may be an adduct of alkylamine with ethylene oxide alone, an adduct of propylene oxide alone, or an adduct of a mixture of ethylene oxide and propylene oxide.
When the polyoxyalkylene alkylamine represented by formula (d-2) is a mixed adduct of ethylene oxide and propylene oxide, the ethylene oxide and propylene oxide may be added randomly or in blocks.

Examples of polyoxyalkylene alkylamines represented by formula (d-2) include Puremeal EP-300S, Puremeal CPE-100, Puremeal PPE-103, Puremeal CCS-80, and Puremeal CF-60, all manufactured by Sanyo Chemical Industries, Ltd.

Examples of the anionic surfactant include anionic surfactants represented by the following formula (d-3):
R ^d10 -SO ₃ H... (d-3)

In formula (d-2), R ^d10 represents a linear or branched alkyl group having from 7 to 20 carbon atoms. The alkyl group may have a hydroxyl group and/or a carboxyl group, and may be interrupted by a phenylene group and/or an oxygen atom.
R ^d10 is preferably a linear or branched alkyl group having 8 to 11 carbon atoms.

Specific examples of anionic surfactants represented by formula (d-2) include n-octanesulfonic acid, n-nonanesulfonic acid, n-decanesulfonic acid, and n-undecanesulfonic acid. Of these, n-octanesulfonic acid, n-nonanesulfonic acid, and n-decanesulfonic acid are preferred.

The content of surfactant (D) in the chemical solution is not particularly limited as long as the desired effect is not impaired. The preferred range of the content of surfactant (D) in the chemical solution is 0.0001% by mass to 10% by mass, more preferably 0.001% by mass to 5% by mass, and even more preferably 0.01% by mass to 1% by mass, based on the mass of the chemical solution.

[Chelating agent (E)]
The chemical solution may contain a chelating agent (E) that does not fall under the category of the carboxylic acid (B). When the chemical solution contains the chelating agent (E), the etching rate of the chemical solution for cobalt tends to be improved.

Examples of the chelating agent include sulfonic acid compounds such as methanesulfonic acid, and phosphonic acid compounds such as methyldiphosphonic acid, aminotri(methylenephosphonic acid), 1-hydroxyethylidene-1,1-diphosphonic acid, nitrilotrismethylenephosphonic acid (NTMP), ethylenediaminetetrakis(methylenephosphonic acid) (EDTPO), hexamethylenediaminetetra(methylenephosphonic acid), propylenediaminetetra(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid), triethylenetetraminehexa(methylenephosphonic acid), triaminotriethylaminehexa(methylenephosphonic acid), trans-1,2-cyclohexanediaminetetra(methylenephosphonic acid), glycol etherdiaminetetra(methylenephosphonic acid), tetraethylenepentaminehepta(methylenephosphonic acid), and glycine-N,N-bis(methylenephosphonic acid) (glyphosine).
These chelating agents may be used in the form of salts such as alkali metal salts and ammonium salts.

The content of the chelating agent (E) in the chemical solution is not particularly limited as long as the desired effect is not impaired. The preferred range of the content of the chelating agent (E) in the chemical solution is 0.01% by mass or more and 20% by mass or less, more preferably 0.1% by mass or more and 10% by mass or less, and even more preferably 0.1% by mass or more and 5% by mass or less, based on the mass of the chemical solution.

[Water-soluble organic solvent (O)]
The chemical solution contains a water-soluble organic solvent (O). By including the water-soluble organic solvent (O) in the chemical solution, cobalt can be etched well using the chemical solution. Here, the water-soluble organic solvent (O) is defined as an organic solvent that can be uniformly mixed in a predetermined amount in the chemical solution at 20°C. The water-soluble organic solvent (O) does not necessarily have to be freely miscible with water at 20°C. The water-soluble organic solvent (O) is preferably a solvent that is freely miscible with water at 20°C.

Specific examples of water-soluble organic solvents (O) include sulfolane; hexamethylphosphoric triamide; sulfoxides such as dimethyl sulfoxide; sulfones such as dimethyl sulfone, diethyl sulfone, ethyl methyl sulfone, ethyl isopropyl sulfone, 3-methyl sulfone, bis(2-hydroxyethyl) sulfone, and tetramethylene sulfone; amides such as N,N-dimethylformamide, N-methylformamide, N,N-dimethylacetamide, N-methylacetamide, and N,N-diethylacetamide; N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-propyl-2-pyrrolidone, N-hydroxymethyl-2-pyrrolidone, and N-hydrogen lactams such as hydroxyethyl-2-pyrrolidone; imidazolidinones such as 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, and 1,3-diisopropyl-2-imidazolidinone; alkanols such as methanol, ethanol, and isopropyl alcohol; glycols such as ethylene glycol, propylene glycol (propane-1,2-diol), 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, and diethylene glycol; glycerin; lactones such as β-propylolactone, γ-butyrolactone, and δ-pentyrolactone; and the like.

Of these water-soluble organic solvents (O), glycols are preferred because they provide a higher etching rate for cobalt (including cobalt alloys, etc.), with ethylene glycol and propylene glycol (propane-1,2-diol) being more preferred, and propylene glycol (propane-1,2-diol) being even more preferred.

The content of the water-soluble organic solvent (O) in the chemical solution is not particularly limited as long as the desired effect is not impaired. For example, the content of the water-soluble organic solvent (O) in the chemical solution is preferably 0.1% by mass or more and 50% by mass or less, more preferably 1% by mass or more and 30% by mass or less, and even more preferably 5% by mass or more and 20% by mass or less, based on the mass of the chemical solution.

[Other ingredients]
The chemical solution may contain, in addition to the above components, an antifoaming agent, etc. The amounts of these components used are determined appropriately taking into consideration the amounts of each component normally used.

[Water (W)]
The chemical solution contains water (W). The water (W) is not particularly limited as long as it does not impair the desired effect, and water of various qualities can be used. As the water (W), for example, ion-exchanged water, distilled water, ion-exchanged distilled water, etc. are preferable, and ion-exchanged distilled water is more preferable.
The chemical solution is prepared by dissolving the required or optional components of the chemical solution described above in desired amounts in water (W).

By using the chemical solution described above, the surface made of cobalt or a cobalt alloy can be selectively etched at a high etching rate while suppressing an increase in surface roughness.
More specifically, for the chemical solution described above, the etching rate ER _Co for cobalt is preferably 10 Å/min or more, more preferably 20 Å/min or more, and even more preferably 30 Å/min or more.
The etching rate ER _W for tungsten is preferably 0.5 Å/min or less, more preferably 0.3 Å/min or less, and even more preferably 0.2 Å/min or less.

In addition, the pH of the chemical solution at 20° C. is preferably 5 or less, more preferably 4.5 or less, and even more preferably 4 or less, in order to easily obtain a sufficiently high cobalt etching rate.
The pH of the chemical solution can be adjusted by adjusting the amount of the amine compound (A) used or the amount of the carboxylic acid (B) used, or by adding a pH adjuster to the chemical solution.

<Method for manufacturing an etched substrate>
The method for producing an etched substrate comprises:
providing a substrate having a region composed of cobalt or a cobalt alloy on at least a portion of a surface thereof;
a step of contacting the substrate with the chemical solution to etch at least a portion of the surface layer;
Includes.

The material of the substrate is not particularly limited as long as the desired effect is not impaired. Typical examples of the substrate include semiconductor substrates and glass substrates. Examples of the substrate material include silicon, silicon germanium, and III-V group compounds such as gallium arsenide.
The shape and size of the substrate are not particularly limited and are appropriately selected depending on the application of the substrate.

The method for providing a region made of cobalt or a cobalt alloy on a substrate is not particularly limited. For example, a region made of cobalt or a cobalt alloy can be provided on a substrate by sputtering, physical vapor deposition (PVD), chemical vapor deposition (CVD), molecular beam epitaxy, or the like.

The thickness of the region made of cobalt or a cobalt alloy in the thickness direction of the substrate is not particularly limited. Typically, the thickness of the region made of cobalt or a cobalt alloy in the thickness direction of the substrate is preferably 10 nm or more and 200 nm or less, and more preferably 50 nm or more and 150 nm or less.

The surface layer of the substrate may consist solely of a region made of cobalt or a cobalt alloy, or may include a region made of a material other than cobalt or a cobalt alloy in addition to the region made of cobalt or a cobalt alloy. Suitable examples of other materials include titanium, titanium alloys, titanium oxide, titanium nitride, tantalum, tantalum alloys, tantalum oxide, tantalum nitride, tungsten, and tungsten alloys. Among these, tungsten and titanium nitride are preferred because of their usefulness in manufacturing semiconductor devices and the ease with which a sufficient difference in etching rate can be achieved between the region made of cobalt or a cobalt alloy and the region made of other materials when etching using the above-mentioned chemical solutions.

The region made of the other material may be present on the surface of the substrate, or may be in contact with the region made of cobalt or a cobalt alloy.

In the step of bringing the above-mentioned chemical solution into contact with the substrate to etch at least a part of the surface layer, the etching method is not particularly limited as long as it is a method that can bring the surface layer of the substrate into contact with the above-mentioned chemical solution.
Examples of etching methods include spraying, immersion, and puddling.
In the spray etching, for example, the substrate is conveyed or rotated in a predetermined direction, and the etching solution is sprayed into the space between the substrate and the surface layer of the substrate, and if necessary, the etching solution may be sprayed onto the substrate while rotating it using a spin coater.
In the immersion etching method, the substrate is immersed in a liquid bath containing a chemical solution, and the surface layer of the substrate is brought into contact with the chemical solution within the liquid bath.
In etching using the puddle method, a chemical solution is puddled on the surface of the substrate, and the surface of the substrate is brought into contact with the chemical solution.
These etching methods may be appropriately selected depending on the structure and material of the substrate.

The time for which the chemical solution is in contact with the surface layer of the substrate is determined appropriately, taking into account factors such as the thickness of the region made of cobalt or a cobalt alloy. The temperature of the chemical solution during etching is not particularly limited, as long as it does not damage the substrate. Typically, the temperature of the chemical solution is preferably 10°C or higher and 70°C or lower, and more preferably 20°C or higher and 40°C or lower.

The present invention will be explained in more detail below using examples, but the scope of the present invention is not limited to the following examples.

[Examples 1 to 11 and Comparative Examples 1 to 3]

The components shown in Table 1 were mixed uniformly in the amounts and types shown therein to obtain the chemical solutions of Examples 1 to 11 and Comparative Examples 1 to 3.
In the examples and comparative examples, triethanolamine (A1) or hydroxylamine (A2) was used as the amine compound (A).
In the examples and comparative examples, citric acid, an aliphatic tricarboxylic acid, was used as carboxylic acid (B).
In the examples and comparative examples, the following C1 to C5 were used as the anticorrosive agent (C).
C1: Benzotriazole C2: 5-methylbenzotriazole C3: Catechol C4: 1,2,4-triazole C5: 1-hydroxybenzotriazole In the examples, polyoxyalkylene alkylamine (Puremeal CCS-80, manufactured by Sanyo Chemical Industries, Ltd.) was used as surfactant (D).
In the examples and comparative examples, propylene glycol was used as the water-soluble organic solvent (O).

The pH of the resulting solution at 20°C was measured, as was the etching rate of the solution for cobalt (Co), tungsten (W), and titanium nitride (TiN), and the surface roughness of the cobalt after etching. The results of these measurements are shown in Table 2.

<Measurement of Etching Rate>
A substrate having a surface layer made of cobalt, a substrate having a surface layer made of tungsten, and a substrate having a surface layer made of titanium nitride were immersed in the chemical solutions of each example and comparative example for 10 minutes at 20° C. to perform etching. After etching, the film thickness of the surface layer of each substrate was measured using X-ray fluorescence analysis (XRF), and the etching rate (Å/min) was calculated.

<Measurement of surface roughness of copper-plated object surface after contact with chemical solution>
Substrates having a surface layer made of cobalt were immersed in the chemical solutions of each Example and Comparative Example at approximately 20°C, and etching was performed until the film thickness of the surface layer was reduced by 10 nm. After etching, the surface of the substrate was rinsed with water and then dried. The surface roughness (root mean square height) of the surface layer after etching was measured using an atomic force microscope.

Tables 1 and 2 show that by using the chemical solution of the example containing the amine compound (A), the carboxylic acid (B), the corrosion inhibitor (C), the water-soluble organic solvent (O), and the water (W), it is possible to preferentially etch only the cobalt or the cobalt alloy while suppressing an increase in the surface roughness after etching.
On the other hand, Tables 1 and 2 show that when the chemical solution of Comparative Example 1 containing the amine compound (A), the carboxylic acid (B), and the water (W) but not containing either the anticorrosive (C) or the water-soluble organic solvent (O) is used, it is not possible to etch cobalt at a sufficiently high etching rate, it is not possible to sufficiently suppress etching of materials other than cobalt, and the surface roughness of the cobalt increases after etching.

Claims (11)

The present invention relates to a method for producing a coating composition comprising an amine compound (A), a carboxylic acid (B), a corrosion inhibitor (C), a water-soluble organic solvent (O), and water (W),
the amine compound (A) is an alkanolamine or a hydroxylamine,
the corrosion inhibitor (C) is one selected from the group consisting of benzotriazole, 5-methylbenzotriazole, catechol, 1,2,4-triazole, and 1-hydroxybenzotriazole;
the water-soluble organic solvent (O) is ethylene glycol or propylene glycol,
A chemical solution for cobalt etching that does not contain any of one or more periodic acids selected from the group consisting of periodic acid and its salts, and one or more hydrazines selected from the group consisting of hydrazine, hydrazine salts, and hydrazine derivatives. The chemical solution according to claim 1, wherein the content of the anticorrosive agent (C) is 0.01% by mass or more and 1% by mass or less relative to the mass of the chemical solution. The present invention relates to a method for producing a coating composition comprising an amine compound (A), a carboxylic acid (B), a corrosion inhibitor (C), a water-soluble organic solvent (O), and water (W),
the amine compound (A) is an alkanolamine or a hydroxylamine,
the corrosion inhibitor (C) is one selected from the group consisting of benzotriazole, 5-methylbenzotriazole, catechol, 1,2,4-triazole, and 1-hydroxybenzotriazole;
the water-soluble organic solvent (O) is ethylene glycol or propylene glycol,
A chemical solution for cobalt etching that does not contain one or more periodic acids selected from the group consisting of periodic acid and its salts,
The content of the anticorrosive agent (C) is 0.01 mass% or more and 1 mass% or less relative to the mass of the chemical solution. The chemical solution according to any one of claims 1 to 3, wherein the content of the water-soluble organic solvent (O) is 5 mass% or more relative to the mass of the chemical solution. The chemical solution according to any one of claims 1 to 4 , wherein the carboxylic acid (B) comprises a polycarboxylic acid having two or more carboxy groups. The chemical solution according to any one of claims 1 to 5 , further comprising a surfactant (D). The drug solution according to any one of claims 1 to 6 , having a pH of 5 or less. The chemical solution according to any one of claims 1 to 7 , wherein the etching rate ERCo for cobalt is 10 Å/min or more. The chemical solution according to any one of claims 1 to 8 , wherein the etching rate ERW for tungsten is 0.5 Å/min or less. providing a substrate having a region composed of cobalt or a cobalt alloy on at least a portion of a surface thereof;
a step of contacting the substrate with the chemical solution according to any one of claims 1 to 9 to etch at least a part of the surface layer;
1. A method for producing an etched substrate, comprising: 11. The method for producing an etched substrate according to claim 10 , wherein the substrate has a region made of tungsten or titanium nitride in at least a portion of the surface layer or in a position adjacent to the region made of cobalt or a cobalt alloy.