Patent Application
20240191360
The present invention relates to a chemical solution for removing a precious metal, a method for manufacturing a chemical solution, a method for treating a substrate, and a method for manufacturing a semiconductor device.
Priority is claimed on United States Patent Application, Application No. 63/431,318, filed on Dec. 9, 2022, the content of which is incorporated herein by reference.
A semiconductor device manufacturing process consists of various multi-stage processing steps. Such processing steps include a process of patterning semiconductor layers, electrodes, and the like by etching or the like. In recent years, following advances in the integration, speed, and the like of semiconductor devices, precious metals such as ruthenium (Ru) have come to the used for wiring and the like.
As a ruthenium-etching solution for etching ruthenium, for example, etching solutions containing othoperiolic acid as an oxidizing agent have been proposed (PCT International Publication No. WO2016/68183 and Japanese Unexamined Patent Application, First Publication No. 2016-92101).
Along with the demand for wiring patterns using precious metals such as ruthenium, there is a demand for the development of chemical solutions having an excellent removal performance for these precious metals. In addition, since the chemical solution may be stored for a long period of time, it is desirable for the chemical solution to have high storage stability.
The present invention was made in view of the above circumstances and has an object of providing a chemical solution having a good removal performance for precious metals such as ruthenium and good storage stability, a method for manufacturing the chemical solution, a method for treating a substrate using the chemical solution, and a method for manufacturing a semiconductor device.
In order to solve the problems described above, the present invention adopted the configurations described below.
A first aspect of the present invention is a chemical solution for removing a precious metal including a cerium-containing oxidizing agent (A), an acid component (B) that is two or more acid components having different pKa's one another, provided that perchloric acid is excluded, and water.
A second aspect of the present invention is a method for manufacturing the chemical solution according to the first aspect, the method including a step for dissolving the cerium-containing oxidizing agent (A) and the acid component (B) in water.
A third aspect of the present invention is a method for treating a substrate, the method including a step for bringing the chemical solution according to the first aspect 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.
A fourth aspect of the present invention is a method for manufacturing a semiconductor device, the method including a step for treating a substrate by the method for treating a substrate according to the third aspect.
According to the present invention, it is possible to provide a chemical solution having a good removal performance for precious metals such as ruthenium and good storage stability, a method for manufacturing the chemical solution, a method for treating a substrate using the chemical solution, and a method for manufacturing a semiconductor device.
The chemical solution according to the first aspect of the present invention includes a cerium-containing oxidizing agent (A), an acid component (B) that is two or more acid components having different pKa's one another, and water. Perchloric acid is excluded from the acid components. The chemical solution of the present embodiment is used to remove precious metals.
The cerium-containing oxidizing agent (also referred to below as “component (A)”) is an oxidizing agent that contains cerium (Ce). Examples of component (A) include cerium nitrate salts and cerium sulfate salts. Examples of cerium nitrate salts include cerium(IV) ammonium nitrate ((NH4)2Ce(NO3)6). Examples of cerium sulfate salts include cerium (IV) ammonium sulfate ((NH4)4Ce(SO4)4) cerium sulfate (Ce(SO4)2), and the like. Component (A) may be used in the form of a hydrate. Examples of the hydrates of component (A) include cerium(IV) ammonium sulfate dihydrate ((NH4)4Ce(SO4)4·2H2O) and cerium(IV) sulfate tetrahydrate (Ce(SO4)2·4H2O).
Among the above, as component (A), cerium (IV) ammonium nitrate, cerium (IV) ammonium sulfate dihydrate, or cerium (IV) sulfate tetrahydrate is preferable and cerium (IV) ammonium nitrate is more preferable.
The chemical solution of the present embodiment may include only one type of component (A), or may include two or more types.
The content of component (A) in the chemical solution of the present embodiment is not particularly limited and examples thereof include 0.01 to 60% by mass with respect to the total mass of the chemical solution. When the content of component (A) is within the above range, the precious metal removal performance of the chemical solution is further improved. The content of component (A) is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, yet more preferably 1.5% by mass or more, and particularly preferably 2% by mass or more. The content of component (A) is preferably 55% by mass or less, more preferably 50% by mass or less, even more preferably 45% by mass or less, and particularly preferably 40% by mass or less. Examples of the content range of component (A) include 0.1 to 55% by mass, 1 to 50% by mass, 1 to 45% by mass, 1.5 to 45% by mass, 1.5 to 40% by mass, and 2 to 40% by mass.
In a case where the content of component (A) in the chemical solution is set in mol/L, the content of component (A) is, for example, 1.0×10−4 to 3.0×100 (mol/L with respect to the volume of the chemical solution. When the content of component (A) is within the above range, the precious metal removal performance of the chemical solution is further improved. The content of component (A) is preferably 2.0×10−4 mol/L or more, more preferably 4.0×10−4 mol/L or more, even more preferably 6.0×10−4 mol/L or more, particularly preferably 8.0×10−4 mol/L or more, and most preferably 1.0×10−3 mol/L or more. The content of component (A) is preferably 2.6=100 mol/L or less, more preferably 2.2×100 mol/L or less, even more preferably 1.8×100 mol/L or less, particularly preferably 1.4×100 mol/L or less, and more particularly preferably 1.0×100 mol/L or less.
The acid component (also referred to below as “component (B)”) is composed of two or more acid components having different pKa's one another. However, perchloric acid is excluded from the acid components. Component (B) is composed at least two or more acid components and may be composed of three or more acid component or be composed of four or more acid component. The two or more acid components composing component (B) have different pKa's one another. The acid components composing component (B) may be an acid or may be a salt. In a case where the acid component composing of component (B) is a salt, an acid salt is preferable.
The acid component composing component (11) may be an inorganic acid or an organic acid. Examples of the acid components composing component (B) include two or more components selected from the group consisting of hydrochloric acid (pKa −5.9), nitric acid (pKa −1.8), sulfuric acid (pKa 1.9%), carbonic acid (pKa 6.11), carboxylic acid, sulfonic acids, and salts thereof. Examples of the carboxylic acid include formic acid (pKa 3.75), acetic acid (pKa 4.76), propionic acid (pKa 4.87), butyric acid (pKa 4.83), and the like. Examples of the sulfonic acid include alkylsulfonic acid, fluoroalkylsulfonic acid, arylsulfonic acid, and the like. Examples of the alkylsulfonic acid include methanesulfonic acid (pKa −2.6), ethanesulfonic acid (pKa 1.83), and the like. Examples of the fluoroalkylsulfonic acid include trifluoromethylsulfonic acid (pKa −14) and the like. Examples of the arylsulfonic acid include benzenesulfonic acid (pKa 0.7). Among the above, methanesulfonic acid is preferable as the sulfonic acid. The inorganic acid may be phosphoric acid, phosphonic acid, or boric acid. The organic acid may be organic phosphoric acid, organic phosphonic acid, organic boric acid, dicarboxylic acid (oxalic acid, succinic acid, malonic acid, or the like), tricarboxylic acid (citric acid or the like), acidic amino acid (glutamic acid or the like), and the like. The pKa value is a value calculated from the concentration measured under conditions of room temperature (25° C.) and normal pressure (I atmospheric pressure), or calculated from a titration curve.
The acid component composing component (B) may be a salt of hydrochloric acid, a salt of nitric acid, a salt of sulfuric acid, a salt of carbonic acid, a salt of carboxylic acid, or a salt of sulfonic acid. The salt is preferably an acid salt. Examples of the salt include salts with alkali metals (sodium, potassium, lithium, or the like), salts with alkaline earth metals (calcium, magnesium, beryllium, or the like), ammonium salts, salts with organic amines, and the like.
One of the acid components composing component (B) is preferably sulfonic acid or a salt thereof. The sulfonic acid is preferably benzenesulfonic acid or methanesulfonic acid, and more preferably methanesulfonic acid. The other one of the acid components composing component (B) is preferably nitric acid, carboxylic acid, or a salt thereof, and more preferably nitric acid, acetic acid, or a salt thereof. Component (B) preferably includes nitric acid and sulfonic acid, more preferably includes nitric acid and benzenesulfonic acid or methanesulfonic acid, and even more preferably includes nitric acid and methanesulfonic acid. Specific examples of component (B) include combinations of organic acids and inorganic acids; combinations of inorganic acids; combinations of organic acids; combinations of nitric acid and one or more selected from the group consisting of sulfonic acid, carboxylic acid, hydrochloric acid, sulfuric acid, and carbonic acid; combinations of sulfonic acid and one or more selected from the group consisting of nitric acid, carboxylic acid, hydrochloric acid, sulfuric acid, and carbonic acid; combinations of carboxylic acid and one or more selected from the group consisting of nitric acid, sulfonic acid, hydrochloric acid, sulfuric acid, and carbonic acid; combinations of sulfuric acid and one or more selected from the group consisting of nitric acid, sulfonic acid, hydrochloric acid, carboxylic acid, and carbonic acid; combinations of hydrochloric acid and one or more selected from the group consisting of nitric acid, sulfonic acid, sulfuric acid, carboxylic acid, and carbonic acid; combinations of carbonic acid and one or more selected from the group consisting of nitric acid, sulfonic acid, hydrochloric acid, carboxylic acid, and sulfuric acid; and the like. Among the above, combinations of nitric acid and methanesulfonic acid, combinations of nitric acid, methanesulfonic acid, and acetic acid; and combinations methanesulfonic acid and acetic acid are preferable.
The content of component (B) in the chemical solution of the present embodiment is, for example, 1.0×10−4 to 1.0×10−4 mol/L with respect to the volume of the chemical solution. When the content of component (B) is within the above range, the precious metal removal performance of the chemical solution is further improved. The content of component (B) is preferably 2.0×10−4 mol/L or more, more preferably 3.0×10−4 mol/L or more, more preferably 4.0×10−4 mol/L or more, more preferably 5.0×10−4 mol/L or more, more preferably 6.0×10−4 mol/L or more, more preferably 7.0×10−4 mol/L or more, even more preferably 8.0×10−4 mol/L or more, and particularly preferably 9.0×10−4 mol/L or more, 1.0×10−3 mol/L or more is most preferable. The content of component (B) is preferably 9.5×100 mol/L or less, more preferably 9.0×10−4 mol/l, or less, more preferably 8.5×100 mol/L or less, more preferably 8.0×100 mol/L or less, more preferably 7.5×100 mol/I, or less, even more preferably 7.0×100 mol/L, or less, particularly preferably 6.5×100 mol/L or less, and most preferably 6.0×100 mol/L or less. When component (B) is within the preferable range described above, the precious metal removal ability and storage stability tend to be good. The content of component (B) described above is the total content of acid components forming component (B).
The number of moles (Am) of component (A) per 1000 mL of the chemical solution and the number of moles (Bm) of component (B) per 100 mL of the chemical solution preferably satisfy condition (I) below.
1.0×10−8≤Am×Bm≤1.0×100 (1)
By satisfying condition (1), the precious metal removal ability and storage stability tend to be good. “Am×Bm” is preferably 2.5×10−4 or more, more preferably 5.0×10−8 or more, more preferably 7.5×10−8 or more, more preferably 1.0×10−7 or more, more preferably 2.5×10−7 or more, even more preferably 5.0×10−6 or more, particularly preferably 7.5×10−7 or more, and most preferably 1.0×10−1 or more.
“Am×Bm” is preferably 9.0×10−1 or less, more preferably 8.0×10−1 or less, more preferably 7.0×10−1 or less, more preferably 6.0×10−1 or less, more preferably 5.0×10−1 or less, more preferably 4.0×10−1 or less, even more preferably 3.0×10−1 or less, particularly preferably 2.0×10−1 or less, and most preferably 1.0×10−1 or less.
The chemical solution of the present embodiment includes water as a solvent for the components described above. The water may include inevitably mixed in trace components. The water used in the chemical solution of the present embodiment is preferably water subjected to a purification process, such as distilled water, ion-exchanged water, or ultrapure water and it is more preferable to use ultrapure water commonly used in semiconductor manufacturing.
The content of the water in the chemical solution of the present embodiment is not particularly limited and is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more. In addition, the upper limit value is not particularly limited and is preferably 99.9% by mass or less, more preferably 99.0%, by mass or less, and even more preferably 98.5% by mass or less.
The chemical solution of the present embodiment may include other components in addition to the components described above, within a range in which the effects of the present invention are not impaired. Examples of other components include pH adjusters, water-soluble organic solvents, surfactants, oxidizing agents other than component (A), anticorrosive agents, buffers, and the like.
pH adjuster
The chemical solution of the present embodiment may include a pH adjuster in order to adjust the pH of the chemical solution in a range not departing from the purpose of the present invention. The pH adjuster is not particularly limited other than being a component able to adjust the pH of the chemical solution. The added amount of the pH adjuster is optional and the added amount may be selected to provide the desired pH.
As the pH adjuster, it is possible to use a basic compound.
The basic compound may be an organic basic compound or an inorganic basic compound. Examples of the organic basic compound include quaternary ammonium salts such as organic quaternary ammonium hydroxide; salts of alkyl amines and derivatives thereof, such as trimethylamine and triethylamine; and the like.
Specific examples of organic quaternary ammonium hydroxides include tetramethylammonium hydroxide (TMAH), bis(2-hydroxyethyl)dimethylammonium hydroxide, tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, methyldiethylammonium hydroxide, trimethyl(hydroxyethyl)ammonium hydroxide, triethyl(hydroxyethyl)ammonium hydroxide, and the like.
Examples of inorganic basic compounds include inorganic compounds including alkali metals or alkaline earth metals and salts thereof. Specific examples of inorganic basic compounds include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, and the like.
The chemical solution of the present embodiment may or may not contain a pH adjuster. 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 pH adjuster. The chemical solution of the present embodiment may or may not contain an acidic compound. The chemical solution of the present embodiment may or may not contain a basic compound.
The chemical solution of the present embodiment may contain a water-soluble organic solvent in a range in which the effects of the present invention are not impaired. Examples of water-soluble organic solvents include alcohols (for example, methanol, ethanol, ethylene glycol, propylene glycol, glycerin, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, diethylene glycol, dipropylene glycol, furfuryl alcohol, 1,6-hexanediol, 2-methyl-2,4-pentanediol, and the like), dimethyl sulfoxide, ethers (for example, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, propylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether, and dipropylene glycol monomethyl ether), ketones (for example, acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, cyclohexanone, and isophorone), esters (for example, γ-butyrolactone, ethyl acetate, butyl acetate, propylene carbonate, and 6-valerolactone), and the like.
In a case where the chemical solution of the present embodiment includes a water-soluble organic solvent, the content of the water-soluble organic solvent is preferably 50% by mass or less with respect to the total amount of water and amount of water-soluble organic solvent, more preferably 30% by mass or less, and even more preferably 10% by mass or less. The chemical solution of the present embodiment may not contain a water-soluble organic solvent. 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 water-soluble organic solvent.
The chemical solution of the present embodiment may include a surfactant. By containing a surfactant, it is possible to adjust the wettability of the chemical solution with respect to the substrate. As the surfactant, it is possible to use nonionic surfactants, anionic surfactants, cationic surfactants, or amphoteric surfactants, and the above may be used in combination.
Examples of nonionic surfactants include polyalkylene oxide alkyl phenyl ether-based surfactants, polyalkylene oxide alkyl ether-based surfactants, block polymer-based surfactants consisting of polyethylene oxide and polypropylene oxide, polyoxyalkylene di styrenated phenyl ether-based surfactants, polyalkylene tribenzyl phenyl ether-based surfactants, acetylene polyalkylene oxide-based surfactants, and the like.
Examples of anionic surfactants include alkylsulfonic acids, alkylbenzenesulfonic acids, alkylnaphthalene sulfonic acids, alkyldiphenyl ether sulfonic acids, fatty acid amide sulfonic acids, polyoxyethylene alkyl ether carboxylic acids, polyoxyethylene alkyl ether acetic acids, polyoxyethylene alkyl ether propionic acids, allylphosphonic acid, fatty acid salts, and the like. Examples of the “salt” include ammonium salt, sodium salt, potassium salt, tetramethylammonium salt, and the like.
Examples of cationic surfactants include quaternary ammonium salt-based surfactants, alkylpyridium-based surfactants, and the like.
Examples of amphoteric surfactants include betaine-type surfactants, amino acid-type surfactants, imidazoline-type surfactants, amine oxide-type surfactants, and the like.
These surfactants are generally commercially available. One type of surfactant may be used alone, or two or more types may be used in combination.
The chemical solution of the present embodiment may or may not contain a surfactant. The chemical solution of the present embodiment may or may not contain one or more selected from the group consisting of nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants. 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 surfactant.
Oxidizing Agents Other than Component (A)
In addition to the component (A), the chemical solution of the present embodiment may or may not include other oxidizing agents. Examples of oxidizing agents include transition metal oxides, peroxides, nitrates, nitrites, iodic acids, iodates, periodates, perchlorates, persulfuric acid, persulfates, peracetic acid, peracetic acid salts, permanganate compounds, dichromate compounds, and the like. The chemical solution of the present embodiment may not contain one or more of the compounds described above as specific examples of the oxidizing agent.
The chemical solution of the present embodiment may contain an anticorrosive agent.
Examples of anticorrosive agents include compounds including nitrogen-containing heterocycles such as triazole rings, imidazole rings, pyridine rings, phenanthroline rings, tetrazole rings, pyrazole rings, pyrimidine rings, and purine rings.
Examples of compounds including a triazole ring include triazoles such as 1,2,3-triazole, 1,2,4-triazole, 3-amino-1H-1,2,4-triazole, 1-acetyl-1H-1,2,3-triazolo[4,5-b]pyridine, 1H-1,2,3-triazolo[4,5-b]pyridine, 1,2,4-triazolo[4,3-a]pyridine-3(2H)-one, and 3H-1,2,3-triazolo[4,5-b]pyridine-3-ol; benzotriazoles such as 1,2,3-benzotriazole, 5-methyl-1H-benzotriazole, 1-hydroxybenzotriazole, 1-dihydroxypropylbenzotriazole, 2,3-dicarboxypropylbenzotriazole, 4-hydroxybenzotriazole, 4-carboxyl-1H-benzotriazole, 4-carboxyl-1H-benzotriazole methyl ester, 4-carboxyl-AH-benzotriazole butyl ester, 4-carboxyl-1H-benzotriazole octyl ester, 5-hexylbenzotriazole, [1,2,3-benzotriazolyl-1-methyl][1,2,4-triazolyl-1-methyl][2-ethylhexyl]amine, tolyltriazole, naphthothiazole, bis[(1-benzotriazolyl)methyl]phosphonic acid, and 3-aminotriazole; and the like.
Examples of compounds including an imidazole ring include imidazoles such as 2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, 2-propylimidazole, 2-butylimidazole, 4-methylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, and 2-aminoimidazole; bisimidazoles such as 2,2′-biimidazole; and the like. Among the above, biimidazole is preferable and 2,2′-biimidazole is more preferable.
Examples of compounds including a pyridine ring include pyridines such as 1H-1,2,3-triazolo[4,5-b]pyridine, 1-acetyl-1H-1,2,3-triazolo[4,5-b]pyridine, 3-aminopyridine, 4-aminopyridine, 3-hydroxypyridine, 4-hydroxypyridine, 2-acetamidopyridine, 4-pyrrolidinopyridine, 2-cyanopyridine, 2,6-pyridinecarboxylic acid, and 2,4,6-trimethylpyridine; bipyridyls such as 2,2′-bipyridyl, 4,4′-dimethyl-2,2′-bipyridyl, 4,4′-di-tert-butyl-2,2′-bipyridyl, 4,4′-dinonyl-2,2′-bipyridyl, 2,2″-bipyridine-6,6′-dicarboxylic acid, and 4,4′-dimethoxy-2,2′-bipyridyl, and the like. Among the above, bipyridyls are preferable and 2,2′-bipyridyl, 4,4′-dimethyl-2,2′-bipyridyl, 4,4′-di-tert-butyl-2,2′-bipyridyl, 4,4′-dinonyl-2,2′-bipyridyl, 2,2″-bipyridine-6,6′-dicarboxylic acid, 4,4′-dimethoxy-2,2′-bipyridyl are more preferable.
Examples of compounds including a phenanthroline ring include 1,10-phenanthroline and the like.
Examples of compounds including a tetrazole ring include 1H-tetrazole, 5-amino-1H-tetrazole, 5-methyl-1H-tetrazole, 5-phenyl-1H-tetrazole, 1-(2-diaminoethyl)-5-mercaptotetrazole, and the like.
Examples of compounds including a pyrazole ring include 3,5-dimethylpyrazole, 3-amino-5-methylpyrazole, 4-methylpyrazole, 3-amino-5-hydroxypyrazole, and the like.
Examples of compounds including a pyrimidine ring include pyrimidine, 4-methylpyrimidine, 1,2,4-triazolo[1,5-a]pyrimidine, 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine, 1,3-diphenyl-pyrimidine-2,4,6-trione, 1,4,5,6-tetrahydropyrimidine, 2,4,5,6-tetraaminopyrimidine sulfate, 2,4,5-trihydroxypyrimidine, 2,4,6-triaminopyrimidine, 2,4,6-trichloropyrimidine, 2,4,6-trimethoxypyrimidine, 2,4,6-triphenylpyrimidine, 2,4-diamino-6-hydroxypyrimidine, 2,4-diaminopyrimidine, 2-acetamidopyrimidine, 2-aminopyrimidine, 2-methyl-5,7-diphenyl-(1,2,4)triazolo(1,5-a)pyrimidine, 2-methylsulfanyl-5,7-diphenyl-(1,2,4)triazolo(1,5-a)pyrimidine, 2-methylsulfanyl-5,7-diphenyl-4,7-dihydro-1,2,4)triazolo(1,5-a)pyrimidine, 4-aminopyrazolo[3,4-d]pyrimidine, and the like.
Examples of compounds including purine rings include adenine, guanine, hypoxanthine, xanthine, uric acid, theophylline, and the like.
In addition, examples of anticorrosive agents include ascorbic acids such as ascorbic acid, ascorbic acid phosphate, and ascorbic acid sulfate; catechols such as pyrocatechol, 4-tert-butylcatechol, pyrogallol, gallic acid, methyl gallate, 1,2,4-benzenetriol, and tiron; sugars such as fructose, glucose and ribose; and polycarboxylic acids such as polyacrylic acid, polymaleic acid, and copolymers thereof, and the like.
One type of anticorrosive agent 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 an anticorrosive agent, the content of the anticorrosive agent is not particularly limited, but is preferably 0.001% by mass to 10% by mass with respect to the total mass of the chemical solution, more preferably 0.001% by mass to 7% by mass, even more preferably 0.01% by mass to 5% by mass, and particularly preferably 0.1% by mass to 3% by mass.
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.
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 the buffer include Good's buffers. Examples of Good's buffers include 2-cyclohexylaminoethanesulfonic acid (CHES), 3-cyclohexylaminoprpanesulfonic 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-morpholinopropanesulfinic 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 (I 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 pH 1.0 in the chemical solution using Hammett's acidity function, for example.
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.
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 ppg or more. The total content of organic impurities is, for example, 1 ppg 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 2,000 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 300 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 (Ir), 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 (CV D) 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.
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.
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 and the storage stability is improved by containing component (B) composed of two or more acid components having different pKa's one another in addition to (A) component that is the cerium-containing oxidizing agent. Therefore, by using the chemical solution of the present embodiment, it is possible to efficiently treat a substrate including a precious metal-containing layer. In addition, it is possible to store the chemical solution of the present embodiment for a long period of time. In the case of storage for a long period of time, the storage period is, for example, one month or more, preferably two moths or more, more preferably three months or more, and even more preferably four months or more. It is possible to evaluate the quality during the storage period, for example, by the presence or absence of precipitates in the 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)>
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 nm or more. The opening of the filter is preferably 1.0 μm or less, more preferably 0.5 μm or less, even more preferably 0.2 μm or less, and particularly preferably 0.1 μm or less.
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 (tor example, sputtering), a CVD method, a molecular beam epitaxy (MBE) method. ALD, 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.
<Step for Removing at Least Part of Precious Metal from Substrate>
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 adhering 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 adhering 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 adhering 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 adhering 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 0.05 to 10% by mass hydrofluoric acid), hydrochloric acid (preferably 0.001 to 1% by mass hydrochloric acid), hydrogen peroxide (preferably a 0.05 to 6% 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 0.01 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. TMA 1 aqueous solution, choline aqueous solution, and hydrogen water are intended to be aqueous solutions in which O. CO2, NH3, methylammonium hydroxide ([(CH3)4N]+[OH]−), choline (trimethyl-2-hydroxyethylammonium hydroxide; [(CH3)3N(CH2)2OH]+[OH]−), and H2 are 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.
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 (layer 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.
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.
Each component shown in Tables 1 to 3 was mixed to prepare a chemical solution for each example.
The abbreviations in Tables 1 to 3 represent the following compounds.
Table 4 shows the values ((Am)×(Bm)) obtained by multiplying the number of the moles of component (A) (Am) per 100 mil of chemical solution and the number of moles of total of component (B) (Bm) per 100 mL of chemical solution in each example.
A ruthenium substrate was used in which a ruthenium film (thickness: 60 nm) was formed on a 12-inch silicon substrate using the PVD method. An etching treatment was performed by putting the chemical solution of each example into a beaker and immersing the ruthenium substrate in the chemical solution of each example for 3 minutes at room temperature (25° C.). During the etching treatment, the beaker was stirred at 300 rpm. After the etching treatment, the ruthenium substrate was taken out from the chemical solution, washed with water, and dried by nitrogen blowing.
The film thickness of the ruthenium substrate was measured before immersion in the chemical solution and after immersion in the chemical solution. A fluorescent X-ray analysis (XRF) device (ZSX Primus IV, Rigaku) was used to measure the film thickness. The etching rate was calculated from the change in the film thickness of the ruthenium film before and after the etching treatment. Using the etching rate (standard ER) in Comparative Example 1 as a standard, the etching rate increase rate (ER increase rate.) in each example was calculated using the following equation. The results are shown in Tables 5 to 7 as the “ER increase rate”.
ER increase rate (%=(ER−standard ER)/standard ER×10)
The chemical solution of each example was stored at 30° C., for 4 months or more. The presence or absence of precipitates in the chemical solution was periodically visually confirmed and evaluated using the following evaluation criteria. The results are shown in Tables 5 to 7 as “storage stability”.
A: The period during which no precipitates were observed was 4 months or more.
B: The period during which no precipitates were observed was 2 months or more and less than 4 months.
C: The period during which no precipitates were observed was 1 month or more and less than 2 months.
D: The period during which no precipitates were observed was less than 1 month.
E: Precipitates were confirmed during the preparation of the chemical solution.
From the results shown in Tables 5 to 7, it was confirmed that the chemical solutions of Examples 1 to 4 increased the etching rate of ruthenium and improved the storage stability compared to the chemical solutions of Comparative Examples 1 to 10. From these results, it was confirmed that the removal performance of precious metals such as ruthenium and the storage stability were improved due to component (B) being contained in the chemical solution.
While preferred embodiments of the invention have been described and illustrated above, it should be understood that these are exemplary of the invention and are not to be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the spirit or scope of the present invention. Accordingly, the invention is not to be considered as being limited by the foregoing description, and is only limited by the scope of the appended claims.
| Number | Date | Country | |
|---|---|---|---|
| 63431318 | Dec 2022 | US |
