Etching solution and method for manufacturing semiconductor device using same

Abstract

To provide an etchant by which a satisfactory etching face can be formed on a surface of a copper-containing metal layer while controlling an etching quantity, and a method for manufacturing a semiconductor device by use thereof.SOLUTION: An etchant is arranged for etching a surface of a copper-containing metal layer. The etchant comprises (A) 0.01-0.5 mass% of hydrogen peroxide based on a total mass of the etchant, (B) 0.01-20 mass% of organic acid of which the minimum acid dissociation constant pKa is 2.0 or larger, (C) 0.005-0.3 mass% of a nitrogen-containing hetero-monocyclic compound, and (D) water. The content of the inorganic acid is less than 0.1 mass%.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an etching solution for etching the surface of a copper-containing metal layer and a method for manufacturing a semiconductor device using the same. [Background technology]

[0002] In recent years, with the trend toward smaller, lighter, and more sophisticated electronic devices, there has been a demand for finer and denser metal wiring in semiconductor devices such as semiconductor elements and integrated circuits. Accordingly, there has been a demand for improved metal wiring processing techniques, and in some cases, it has been required to perform etching while controlling the amount of etching. For example, in multilayer wiring technology, as metal wiring becomes finer and denser, misalignment when connecting upper and lower metal wiring layers makes it more likely for short circuits to occur in the metal wiring, which is one of the factors that reduces yield in semiconductor device manufacturing lines.The Fully Self-Aligned Via (FSAV) process is one approach to addressing the above problem, and proposes performing extremely small recess etching on the surface of the metal embedded in vias or trenches in the lower metal wiring layer, thereby increasing the distance between adjacent vias or trenches and making short circuits less likely to occur. Conventionally, a dry etching process is used after chemical polishing, but the dry etching process may have an adverse effect on the environment, so it is preferable to use a wet etching process. Patent Document 1 describes that an etching solution containing hydrogen peroxide, a fluorine-free inorganic acid, an organic acid, an amine compound, an azole, and a hydrogen peroxide stabilizer and having a pH of 2.5 to 5 is suitable for etching a multilayer thin film containing a copper layer and a molybdenum layer. Patent Document 2 describes that a copper or copper alloy surface treatment agent containing hydrogen peroxide, a mineral acid, an azole, and an aromatic amine compound can be used to uniformly roughen the copper surface, thereby improving adhesion to dry film resists and the like. Furthermore, Patent Document 3 describes that an aqueous solution containing hydrogen peroxide, phosphoric acid, and an amino group-containing azole can finish copper and copper alloy surfaces to have good adhesion to dry film resists and the like without roughening the surface. However, with conventional etching solutions, it has been difficult to form a desired etched surface on the surface of a copper-containing metal layer while controlling the amount of etching. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2011 / 099624 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-133147 [Patent Document 3] Japanese Patent Application Laid-Open No. 2009-299096 Summary of the Invention [Problem to be solved by the invention]

[0004] It is desired to provide an etching solution that can form a good etched surface on the surface of a copper-containing metal layer while controlling the etching amount, and a method for manufacturing a semiconductor device using the same. [Means for solving the problem]

[0005] The present invention relates to the following etching solution and method for manufacturing a semiconductor device. [1] An etching solution for etching the surface of a copper-containing metal layer, the etching solution comprising, based on the total amount of the etching solution: (A) 0.01 to 0.5 mass% hydrogen peroxide, (B) 0.01 to 20 mass% of an organic acid having a minimum acid dissociation constant pKa of 2.0 or more; (C) 0.005 to 0.3 mass% of a nitrogen-containing heteromonocyclic compound, and (D) contains water; The etching solution has an inorganic acid content of less than 0.1% by mass. [2] The etching solution according to [1] above, wherein the component (B) is a carboxylic acid having less than three carboxyl groups. [3] The etching solution according to [1] or [2], wherein the component (B) is a carboxylic acid having less than two hydroxyl groups and one or more carbon atoms not included in the carboxyl group. [4] The etching solution according to any one of [1] to [3], wherein the component (B) is one or more selected from the group consisting of malic acid, succinic acid, lactic acid, and acetic acid. [5] The etching solution according to any one of [1] to [4], wherein the component (C) is one or more selected from the group consisting of triazoles, tetrazoles, thiazoles, pyrazoles, imidazoles, and nucleic acid bases. [6] The etching solution according to [5] above, wherein the component (C) is one or more selected from tetrazoles having a substituent at the 5-position. [7] The etching solution according to [6], wherein the component (C) is 5-aminotetrazole. [8] The etching solution according to any one of [1] to [7] above, having a pH value of less than 4.0. [9] The etching solution according to any one of [1] to [8] above, wherein the etching rate of copper is in the range of 2.0 to 10.0 nm per minute.

[10] The etching solution according to any one of [1] to [9] above, which is used to perform recess etching on the surface of a copper-containing metal layer embedded in a via or trench formed in a semiconductor substrate.

[11] A method for manufacturing a semiconductor device, comprising the step of contacting the surface of a copper-containing metal layer with the etching solution according to any one of [1] to

[10] above to perform etching.

[12] The method for manufacturing a semiconductor device according to

[11] , wherein the step includes bringing the etching solution into contact with a surface of a copper-containing metal layer embedded in a via or trench formed in a semiconductor substrate to perform recess etching. [Effects of the Invention]

[0006] The etching solution of the present invention is suitably used as an etching solution for the surface of a copper-containing metal layer. According to a preferred embodiment of the present invention, a good etched surface can be formed while controlling the etching amount. [Brief explanation of the drawings]

[0007] [Figure 1] 1A to 1C are explanatory views of a recess etching process using the etching solution of the present invention. [Figure 2] SEM image (a) of the surface of the evaluation sample after etching treatment in Example 1, SEM image (b) of the surface of the evaluation sample after etching treatment in Comparative Example 10, and SEM image (c) of the surface of the untreated evaluation sample (each observed at a magnification of 100,000 times). DETAILED DESCRIPTION OF THE INVENTION

[0008] 1. Etching solution The etching solution of the present invention is an etching solution for etching the surface of a copper-containing metal layer, and contains, based on the total amount of the etching solution, (A) 0.01 to 0.5 mass% hydrogen peroxide, (B) 0.01 to 20 mass% of an organic acid having a minimum acid dissociation constant pKa of 2.0 or more; (C) 0.005 to 0.3 mass% of a nitrogen-containing heteromonocyclic compound, and (D) contains water; It is characterized by having an inorganic acid content of less than 0.1% by mass.

[0009] Each component will be described below. (A) Hydrogen peroxide In the present invention, hydrogen peroxide (hereinafter also referred to as component (A)) is a component that functions as an oxidizing agent for copper. There are no particular limitations on component (A), and various grades can be used, including those for industrial and electronics industries. In general, it is preferable to use an aqueous hydrogen peroxide solution in terms of availability and ease of use.

[0010] The content of component (A) is in the range of 0.01 to 0.5 mass% based on the total amount of the etching solution, preferably 0.02 to 0.4 mass%, more preferably 0.03 to 0.35 mass%, even more preferably 0.04 to 0.3 mass%, particularly preferably 0.05 to 0.25, and still more preferably 0.05 to 0.2. In the present invention, by having the content of component (A) within the above range, the amount of etching can be controlled, and a smooth surface can be formed without roughening. When a numerical range is given in this specification, the upper and lower limits can be combined as appropriate, and the resulting numerical range is also considered to be disclosed.

[0011] (B) Organic acids with a minimum acid dissociation constant pKa of 2.0 or more In the present invention, the organic acid having a minimum acid dissociation constant pKa of 2.0 or more (hereinafter also referred to as component (B)) has an etching action on the copper-containing metal layer. Component (B) is not particularly limited as long as it has a minimum acid dissociation constant pKa of 2.0 or more. That is, when a molecule contains multiple acidic hydroxyl groups, dissociation occurs stepwise, resulting in multiple pKa values. In this case, component (B) contains an organic acid whose minimum acid dissociation constant pKa is 2.0 or more. The minimum acid dissociation constant pKa of component (B) is preferably 2.5 or more and 7 or less, more preferably 3.0 or more and 6 or less, even more preferably 3.1 or more and 5.5 or less, and particularly preferably 3.2 or more and 5 or less.

[0012] Examples of component (B) include carboxylic acids such as aliphatic carboxylic acids and aromatic carboxylic acids, and amino acids. Of these, carboxylic acids with less than three carboxyl groups are preferred, and carboxylic acids with 1 or 2 carboxyl groups are more preferred. As the carboxylic acid, aliphatic carboxylic acids and aromatic carboxylic acids are preferred, and one or more selected from the group consisting of aliphatic carboxylic acids having 1 to 12 carbon atoms and aromatic carboxylic acids having 6 to 16 carbon atoms are more preferred, and aliphatic carboxylic acids having 1 to 6 carbon atoms are particularly preferred. Furthermore, as component (B), a carboxylic acid having less than two hydroxyl groups and one or more carbon atoms not included in the carboxyl groups is more preferred, and a carboxylic acid having zero or one hydroxyl group and one or two carbon atoms not included in the carboxyl groups is even more preferred.

[0013] Examples of aliphatic carboxylic acids include formic acid, acetic acid, propionic acid, lactic acid, glycolic acid, diglycolic acid, butyric acid, hydroxybutyric acid, succinic acid, malic acid, valeric acid, glutaric acid, itaconic acid, adipic acid, caproic acid, propanetricarboxylic acid, enanthic acid, caprylic acid, nonanoic acid, capric acid, lauric acid, myristic acid, palmitic acid, and sorbic acid. These can be used alone or in combination of two or more. Among these, preferred aliphatic carboxylic acids are acetic acid, lactic acid, succinic acid, malic acid, propionic acid, glycolic acid, and combinations thereof.

[0014] Examples of aromatic carboxylic acids include benzoic acid, terephthalic acid, mandelic acid, 2-methylbenzoic acid, 3-methylbenzoic acid, 4-methylbenzoic acid, 2-ethylbenzoic acid, 3-ethylbenzoic acid, 4-ethylbenzoic acid, 3-hydroxybenzoic acid, 4-hydroxybenzoic acid, 3-chlorobenzoic acid, 4-chlorobenzoic acid, 2-fluorobenzoic acid, 3-fluorobenzoic acid, 4-fluorobenzoic acid, 2-cyanobenzoic acid, 3 -Cyanobenzoic acid, 4-cyanobenzoic acid, 3-nitrobenzoic acid, 4-nitrobenzoic acid, 2,3-dimethylbenzoic acid, 3,4-dimethylbenzoic acid, 3,5-dimethylbenzoic acid, 2,5-dimethylbenzoic acid, 2,6-dimethylbenzoic acid, 2-hydroxy-4-methylbenzoic acid, 2-hydroxy-5-methylbenzoic acid, 2-hydroxy-6-methylbenzoic acid, 3-hydroxy-2-methylbenzoic acid, 3-hydroxy 4-methylbenzoic acid, 3-hydroxy-5-methylbenzoic acid, 5-hydroxy-2-methylbenzoic acid, 4-hydroxy-2-methylbenzoic acid, 4-hydroxy-3-methylbenzoic acid, 2-methoxybenzoic acid, 3-methoxybenzoic acid, 4-methoxybenzoic acid, 3,4-dihydroxybenzoic acid, 3,5-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, 2,4,5-trimethylbenzoic acid, 2,4,6-trimethylbenzoic acid, 1-naphthalenecarboxylic acid, 2-naphthalenecarboxylic acid, 1-hydroxy-2-naphthalenecarboxylic acid, 6-hydroxy-1-naphthalenecarboxylic acid, 6-hydroxy-2-naphthalenecarboxylic acid, 2-hydroxy-1-naphthalenecarboxylic acid, 1-anthracenecarboxylic acid, 2-anthracenecarboxylic acid, 9-anthracenecarboxylic acid, gallic acid, and cinnamic acid. These can be used alone or in combination of two or more.

[0015] As component (B), either an aliphatic carboxylic acid or an aromatic carboxylic acid may be used alone, or an aliphatic carboxylic acid and an aromatic carboxylic acid may be used in combination, but it is more preferable to use one or more aliphatic carboxylic acids.

[0016] The content of component (B) is 0.01 to 20 mass%, preferably 0.01 to 19.5 mass%, more preferably 0.01 to 19.0 mass%, even more preferably 0.01 to 18.5 mass%, and particularly preferably 0.01 to 18.0 mass%, based on the mass of the etching solution. When two or more compounds are used as component (B), the total amount thereof should be within the above range.

[0017] (C) Nitrogen-containing heteromonocyclic compound In the present invention, the nitrogen-containing heteromonocyclic compound (hereinafter also referred to as component (C)) can act as a copper corrosion inhibitor. Component (C) is not particularly limited as long as it contains a nitrogen atom as a heteroatom constituting the ring. Examples of the compound include triazoles, tetrazoles, thiazoles, pyrazoles, imidazoles, and nucleic acid bases.

[0018] Examples of triazoles include 1,2,3-triazole, 1,2,4-triazole, 3,5-dimethyl-1,2,4-triazole, 3-amino-1,2,4-triazole, 4-amino-1,2,4-triazole, 3-mercapto-4-methyl-4H-1,2,4-triazole, 1H-benzotriazole, 1H-benzotriazole-1-methanol, 4-methyl-1H-benzotriazole, 2-(2-hydroxy-5-methylphenyl)benzotriazole, 5-methyl-1H-benzotriazole, 3-chloro-1H-benzotriazole, 5-chloro-1H-benzotriazole, 1,2,4-triazole-3-methyl carboxylate, 2-(5-chloro-2-benzotriazolyl)-6-tertbutyl-p-cresol, and 3-amino-1H-triazole. Examples of tetrazoles include 1H-tetrazole, 5-methyl-1H-tetrazole, 5-phenyl-1H-tetrazole, 5-mercapto-1-methyl-1H-tetrazole, 5-mercapto-1-phenyl-1H-tetrazole, 5-benzyl-1H-tetrazole, and 5-amino-1H-tetrazole. Thiazoles include, for example, 1,3-thiazole and 4-methylthiazole. Examples of pyrazoles include pyrazole and 3,5-dimethylpyrazole. Examples of imidazoles include imidazole, 2-methylimidazole, 1-propylimidazole, 1-isopropylimidazole, 2-undecylimidazole, 2-phenylimidazole, benzimidazole, 2-methylbenzimidazole, and 2-hydroxybenzimidazole. Examples of nucleic acid bases include pyrimidine, uracil, thymine, and cytosine, which can be used alone or in combination of two or more. Among these, tetrazoles are preferred as component (C), and one or more selected from tetrazoles having a substituent at the 5-position are more preferred. In this case, the substituent may be a group having 1 to 10 carbon atoms (C1 to C 10 ) hydrocarbon groups (e.g., C1-C 10 Alkyl groups, C1-C 10 Alkenyl groups, C1-C 10 Alkynyl groups, C6-C 10 Aryl groups, C7-C 10 Alkylaryl group, C7-C 10 Aryl alkyl group, carbon number 1 to 10 (C1 to C 10 ) alkoxy group, carbon number 7 to 10 (C7 to C 10 ) alkylaryloxy group having 2 to 10 carbon atoms (C2 to C 10 ), an amino group which may have a substituent (for example, an amino group, a dimethylamino group, a methylamino group, a methylphenylamino group, a phenylamino group, etc.), a hydroxyl group, a mercapto group, etc. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, an octyl group, a nonyl group, and a decyl group. Examples of the alkenyl group include a vinyl group, an allyl group, a propenyl group, an isopropenyl group, a 2-methyl-1-propenyl group, a 2-methylallyl group, and a 2-butenyl group. Examples of the alkynyl group include an ethynyl group, a propynyl group, and a butynyl group. Examples of the aryl group include a phenyl group, a 1-naphthyl group, a 2-naphthyl group, an indenyl group, a biphenyl group, an anthryl group, and a phenanthryl group. Examples of the alkylaryl group include a tolyl group, a xylyl group, a cumenyl group, and a mesityl group. Examples of the arylalkyl group include a benzyl group, a phenethyl group, a 1-naphthylmethyl group, a 2-naphthylmethyl group, a 1-phenylethyl group, a phenylpropyl group, a phenylbutyl group, a phenylpentyl group, a phenylhexyl group, a methylbenzyl group, a dimethylbenzyl group, a trimethylbenzyl group, an ethylbenzyl group, a methylphenethyl group, a dimethylphenethyl group, and a diethylbenzyl group. Among these, 5-amino-1H-tetrazole is preferred as component (C).

[0019] The content of component (C) is 0.005 to 0.3 mass%, preferably 0.005 to 0.2 mass%, more preferably 0.005 to 0.15 mass%, and even more preferably 0.005 to 0.1 mass%, based on the mass of the etching solution. When two or more compounds are used as component (C), the total amount thereof should be within the above range.

[0020] (D)Water The etching solution of the present invention contains water (hereinafter also referred to as component (D)) as a diluent. The water is preferably water from which metal ions, organic impurities, particles, etc. have been removed by distillation, ion exchange treatment, filtration, various adsorption treatments, etc., and pure water or ultrapure water is particularly preferred. The content of component (D) is the remainder of the etching solution, and is preferably 70 mass % or more, more preferably in the range of 75 to 99.9 mass %, and even more preferably 80 to 99.9 mass %, based on the mass of the etching solution.

[0021] (E) Other ingredients In addition to the components (A), (B), (C), and (D), the etching solution of the present invention may contain additives that are generally used in etching copper-containing metal layers, such as alcohols, phosphonic acid compounds, glycol compounds, surfactants, oxidizing agents, reducing agents, chelating agents, and alkalis, to the extent that the effects of the present invention are not impaired. However, if an inorganic acid (such as sulfuric acid, nitric acid, hydrochloric acid, or phosphoric acid) is contained, the surface after etching becomes rough, making it difficult to obtain a smooth surface. Therefore, the etching solution of the present invention preferably does not contain substantially any inorganic acid, and the content of inorganic acid is less than 0.1 mass% based on the mass of the etching solution. The content of inorganic acid is preferably less than 0.05 mass%, more preferably less than 0.03 mass%, and even more preferably less than 0.01 mass% based on the mass of the etching solution.

[0022] According to a preferred embodiment of the present invention, the total content of the components (A), (B), (C), and (D) is preferably 95% by mass or more, more preferably in the range of 96 to 100% by mass, even more preferably 97 to 100% by mass, still more preferably 98 to 100% by mass, and particularly preferably 99 to 100% by mass, based on the mass of the etching solution.

[0023] The pH of the etching solution of the present invention is not particularly limited, but the pH is preferably less than 4, more preferably 1.0 to 3.8, even more preferably 1.2 to 3.6, and particularly preferably 1.3 to 3.6. The etching solution of the present invention may contain a pH adjuster, if necessary, to adjust the pH range. Examples of pH adjusters that can be used include potassium hydroxide, lithium hydroxide, cesium hydroxide, triethylamine, ammonia, tetramethylammonium hydroxide, ethanolamine, and 1-amino-2-propanol. One or more pH adjusters can be used.

[0024] The etching solution of the present invention can be prepared by uniformly stirring the components (A) to (D) and, if necessary, other component (E). Note that some or all of the water in component (D) may be added later. Alternatively, a solution containing components (A) to (C), a portion of component (D), and, if necessary, other component (E) may be prepared in advance, stored, and then diluted with the remainder of component (D) before use.

[0025] The etching rate of the etching solution of the present invention for copper at a treatment temperature of 25°C is preferably 2.0 to 10.0 nm per minute (nm / min), more preferably 3.0 to 10.0 nm / min, even more preferably 4.0 to 10.0 nm / min, and particularly preferably 5.0 to 10.0 nm / min. If the etching rate is too high, it becomes difficult to control the amount of etching, and even if the amount of etching is controlled, etching cannot be performed uniformly, making it difficult to obtain a smooth etched surface. Conversely, if the etching rate is too low, the etching process takes a long time, which is undesirable in terms of work efficiency.

[0026] The etching solution of the present invention can uniformly etch the surface of a copper-containing metal layer while controlling the amount of copper etched, thereby forming a good etched surface. Since the etching solution of the present invention can control the amount of copper etched, it can be suitably used when etching a fine region, and can also accommodate miniaturization and high density of metal wiring.

[0027] The etching solution of the present invention can etch the surface of a copper-containing metal layer by contacting the surface with the copper-containing metal layer.

[0028] The temperature at which the etching solution of the present invention is used is not particularly limited, but is, for example, 0 to 70°C, preferably 10 to 50°C, more preferably 20 to 45°C, and even more preferably 25 to 40°C. If the temperature of the etching solution is 10°C or higher, the etching rate is good, resulting in excellent production efficiency. On the other hand, if the temperature of the etching solution is 50°C or lower, changes in the solution composition can be suppressed, and etching conditions can be maintained constant. Increasing the temperature of the etching solution increases the etching rate, but the optimum treatment temperature can be determined appropriately, taking into consideration factors such as minimizing changes in the composition of the etching solution (decomposition of hydrogen peroxide).

[0029] The etching treatment time using the etching solution of the present invention is not particularly limited, but is preferably 15 seconds or more and 10 minutes or less, more preferably 30 seconds or more and 7.5 minutes or less, and even more preferably 30 seconds or more and 5 minutes or less. The treatment time may be appropriately selected depending on various conditions such as the surface condition of the copper-containing metal layer to be etched, the concentration of the etching solution, the temperature, and the treatment method.

[0030] The method for contacting the etching solution with the etching object is not particularly limited. For example, a wet method (wet etching method) can be used, such as a method in which the etching solution is contacted with the etching object by dropping (single wafer spin processing) or spraying, or a method in which the etching object is immersed in the etching solution. Either method can be used in the present invention.

[0031] The etching target of the etching solution of the present invention is a copper-containing metal layer. The copper-containing metal layer is preferably a copper layer or a copper alloy layer. The copper content in the copper alloy layer is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and may be 99% by mass or more. The copper-containing metal layer may be, for example, an electrolytic copper foil, an electrolytic copper-plated film, or an electroless copper-plated film, or a combination thereof.

[0032] The thickness (etching depth) of the copper-containing metal layer etched using the etching solution of the present invention is not particularly limited, but is preferably in the range of 2.5 to 50 nm, more preferably 5 to 40 nm, even more preferably 5 to 35 nm, and particularly preferably 5 to 30 nm. There is no particular limitation on the width (wiring width) of the copper-containing metal layer etched using the etching solution of the present invention, but since the etching amount can be controlled, it is also possible to accommodate narrower pitches of metal wiring.

[0033] The etching solution of the present invention can be suitably used in processing metal wiring in one step of a method for manufacturing a semiconductor device. According to a preferred embodiment of the present invention, the etching solution can form a good etched surface while controlling the etching amount, and therefore can be suitably used in processing fine metal wiring.

[0034] According to one embodiment of the present invention, the etching solution of the present invention can be suitably used as a recess etching solution for performing recess etching on the surface of a copper-containing metal layer embedded in a via or trench formed in a semiconductor substrate.

[0035] 2. Manufacturing method of semiconductor devices Next, a method for manufacturing a semiconductor device according to the present invention will be described. The method for producing a semiconductor device of the present invention includes a step of etching the surface of a copper-containing metal layer by contacting the surface with the etching solution of the present invention.

[0036] The method for contacting the etching solution with the surface of the copper-containing metal layer, the temperature of the etching solution during contact, and the contact time are as described above in "1. Etching solution." After etching by bringing the copper-containing metal layer into contact with the etching solution, the copper-containing metal layer may be appropriately washed, if necessary, with water, isopropyl alcohol, an aqueous ammonia solution, an aqueous tetramethylammonium hydroxide solution, etc. Furthermore, a rust prevention treatment may be performed with an aqueous solution containing a rust inhibitor.

[0037] In one embodiment of the present invention, the process may be a recess etching process in which the etching solution is brought into contact with the surface of a copper-containing metal layer embedded in a via or trench formed in a semiconductor substrate to perform recess etching. In this case, a semiconductor substrate can be manufactured in which recess etching is performed on the surface of a copper-containing metal layer embedded in a via or trench formed in the semiconductor substrate. A wiring circuit can be constructed by stacking additional copper-containing metal layers on this semiconductor substrate.

[0038] 1 is an explanatory diagram of the recess etching process using the etching solution of the present invention, in which only the structures necessary for explaining the recess etching process are shown schematically.

[0039] First, as shown in FIG. 1(a), a semiconductor substrate 100 is prepared having a wiring structure in which a via or a trench is formed in an interlayer insulating film 20 provided on a substrate 10 and a copper-containing metal layer 30 is embedded in the via or the trench. A barrier metal layer 40 such as a titanium layer or titanium nitride layer may be formed on the inner wall of the via or trench. The semiconductor substrate 100 can be manufactured by a method commonly used in the industry, for example, as follows. First, the interlayer insulating film 20 is formed on the substrate 10 . Next, vias or trenches are formed by dry etching or the like in the interlayer insulating film 20. Furthermore, a barrier metal layer 40 is formed on the inner walls of the vias or trenches as required. Subsequently, a copper-containing metal layer 30 is formed so as to fill the via or trench formed in the interlayer insulating film 20 . Finally, by performing CMP (chemical mechanical polishing) as necessary, a semiconductor substrate 100 with a smooth top surface can be obtained.

[0040] Next, as shown in FIG. 1( b ), the surface of the copper-containing metal layer 30 exposed on the upper part of the semiconductor substrate 100 is brought into contact with the etching solution 50 of the present invention.

[0041] There are no particular limitations on the method for bringing the etching solution 50 into contact with the surface of the copper-containing metal layer 30. For example, a method of bringing the etching solution into contact with the surface of the copper-containing metal layer 30 by dropping (single-wafer spin processing) or spraying the etching solution, or a method of immersing the surface of the copper-containing metal layer 30 in the etching solution can be employed.

[0042] The temperature of the etching solution 50 when it is brought into contact with the copper-containing metal layer 30 is not particularly limited, but is, for example, 0 to 70°C, preferably 25 to 65°C, more preferably 25 to 60°C, and even more preferably 25 to 50°C. If the temperature of the etching solution is 25°C or higher, recess etching can be performed in a shorter time. On the other hand, if the temperature is 50°C or lower, changes in the solution composition can be suppressed, and processing conditions can be maintained constant.

[0043] The time (treatment time) for contacting the copper-containing metal layer 30 with the etching solution 50 is not particularly limited, but is usually preferably 15 seconds to 10 minutes, more preferably 30 seconds to 7.5 minutes, and even more preferably 30 seconds to 5 minutes. The optimum treatment time can be selected depending on the method for contacting the copper-containing metal layer with the etching solution, the temperature of the etching solution, etc.

[0044] When recess etching is performed on a copper-containing metal layer using the etching solution of the present invention, the etching rate of the copper-containing metal layer is preferably 2.0 to 10 nm / min, more preferably 3.0 to 10.0 nm / min, even more preferably 4.0 to 10.0 nm / min, and particularly preferably 5.0 to 10.0 nm / min.

[0045] 1(c), recess etching can be performed on the surface of the copper-containing metal layer 30. The barrier metal layer 40 in the recess-etched portion may be removed by separate etching in a step after the recess etching, or may be left as it is and used for the next step without undergoing an etching step.

[0046] There is no particular limitation on the preferred amount of recess etching performed on the copper-containing metal layer (i.e., the depth of the recess formed by performing recess etching on the copper-containing metal layer), but it is preferably 2.5 to 20 nm, more preferably 5 to 15 nm, and even more preferably 7.5 to 12.5 nm.

[0047] In one embodiment of the present invention, the method for manufacturing a semiconductor device of the present invention includes the steps of: a recess etching step of contacting the surface of the copper-containing metal layer embedded in the via or trench formed in the semiconductor substrate with the etching solution to perform recess etching on the surface of the copper-containing metal layer; a step of stacking metal wiring layers on the surface of the copper-containing metal layer in the surface-treated semiconductor substrate obtained in the step above to obtain a semiconductor device that constructs a wiring circuit; Includes.

[0048] According to a preferred embodiment of the present invention, a smooth recess-etched surface can be formed in the copper-containing metal wiring in the recess etching step. This makes it possible to prevent short circuits in the metal wiring when constructing a wiring circuit by stacking metal wiring layers, thereby obtaining a semiconductor device with excellent electrical properties. The metal wiring layer that can be stacked on the surface of the copper-containing metal layer is not particularly limited as long as it contains copper or cobalt and can be electrically connected to the copper-containing metal layer. The metal wiring layer that can be stacked on the surface of the copper-containing metal layer may be one layer or two or more layers. [Example]

[0049] Next, the present invention will be explained in more detail using examples and comparative examples, but the present invention is not limited to these examples in any way.

[0050] Examples 1 to 10 (1) Preparation of etching solution The components were mixed in the composition ratios shown in Table 1 and stirred to a homogeneous state to prepare an etching solution.

[0051] (2) Etching of copper-containing metal layers As a sample for evaluating the etching solution, a Cu electroplated solid film manufactured by Renesas Electronics Corporation, having a copper layer (thickness: 0.6 μm) on the substrate surface, was used. As a pretreatment, the surface of the evaluation sample was brought into contact with an aqueous solution of sulfuric acid (0.1 mass %) at 25° C. for 30 seconds to remove oxides present on the surface of the copper layer. Next, the pretreated surface of the evaluation sample was immersed in the etching solution (25° C.) prepared in (1) above for 1 minute to perform an etching treatment.

[0052] (3) Observation and evaluation of the surface of the copper-containing metal layer after etching The surface of the evaluation sample after etching was observed with a scanning electron microscope (SEM) (device: "Regulus8220" manufactured by Hitachi High-Technologies Corporation) and evaluated according to the following criteria. ◯: The etched surface of the copper-containing metal layer exhibited smoothness equivalent to that of an untreated surface, or only minute deposits were observed. ×: The appearance of depressions or clearly sized precipitates was observed on the etched surface of the copper-containing metal layer. The results are shown in Table 1. As examples of the surfaces of the evaluation samples after etching, surface SEM images (observed at a magnification of 100,000 times) of the evaluation samples after etching in Example 1 and Comparative Example 10 and an untreated evaluation sample are shown in Figures 2(a), (b), and (c), respectively.

[0053] (4) Etching rate of copper-containing metal layer (Cu ER) The etching rate of the copper-containing metal layer was calculated by dividing the difference in thickness of the copper layer before and after the etching treatment by the treatment time.

[0054] Comparative Examples 1 to 10 An etching solution was prepared in the same manner as in the Examples, except that the composition ratio was set as shown in Table 1, and an etching treatment was performed on a copper-containing metal layer using an evaluation sample. The etching rate of the copper-containing metal layer was calculated in the same manner as in the Examples, and the surface after etching was observed and evaluated.

[0055] The results are shown in Table 1.

[0056] [Table 1]

[0057] As shown in Table 1, by treating a copper-containing metal layer with the etching solution of the present invention, a smooth etched surface can be obtained while controlling the etching rate (Examples 1 to 10). According to a preferred embodiment of the present invention, it is also possible to control the amount of etching in units of several nanometers to several tens of nanometers. On the other hand, if the etching rate is too high, the amount of etching will vary when the etching amount is controlled, making it difficult to obtain a smooth etched surface. Also, if the etching rate is too low, this is not preferable in terms of work efficiency. As shown by the above results, the etching solution of the present invention has an etching rate within an appropriate range and is excellent in obtaining a smooth etched surface while controlling the etching amount in the treatment of a copper-containing metal layer. The etching solution of the present invention is particularly suitable for applications where it is necessary to control the etching amount and where the smoothness of the etched surface is important, such as recess etching. [Explanation of symbols]

[0058] 10 Substrate 20 Interlayer insulating film 30 Copper-containing metal layer 40 Barrier metal layer 50 Etching Solution 60 Recess etching amount 100 Semiconductor substrate

Claims

1. An etching solution for etching a surface of a copper-containing metal layer, the etching solution comprising, based on the total amount of the etching solution: (A) 0.01 to 0.3 mass% hydrogen peroxide, (B) 0.01 to 20% by mass of an organic acid having a minimum acid dissociation constant pKa of 2.0 or more; (C) 0.005 to 0.3 mass% of a nitrogen-containing heteromonocyclic compound, and (D) contains water, The etching solution, wherein the content of the inorganic acid is less than 0.1% by mass.

2. 2. The etching solution according to claim 1, wherein the component (B) is a carboxylic acid having less than three carboxyl groups.

3. 3. The etching solution according to claim 1, wherein the component (B) is a carboxylic acid having less than two hydroxyl groups and one or more carbon atoms not contained in the carboxyl group.

4. 4. The etching solution according to claim 1, wherein the component (B) is at least one selected from the group consisting of malic acid, succinic acid, lactic acid, and acetic acid.

5. 5. The etching solution according to claim 1, wherein the component (C) is at least one selected from the group consisting of triazoles, tetrazoles, thiazoles, pyrazoles, imidazoles, and nucleic acid bases.

6. 6. The etching solution according to claim 5, wherein the component (C) is one or more selected from tetrazoles having a substituent at the 5-position.

7. The etching solution according to claim 6, wherein the component (C) is 5-aminotetrazole.

8. 8. The etching solution according to claim 1, wherein the pH value is less than 4.

0.

9. The etching solution according to any one of claims 1 to 8, wherein the etching rate of copper is in the range of 2.0 to 10.0 nm per minute.

10. The etching solution according to claim 1 , which is used to perform recess etching on a surface of a copper-containing metal layer embedded in a via or trench formed in a semiconductor substrate.

11. A method for manufacturing a semiconductor device, comprising the step of contacting the surface of a copper-containing metal layer with the etching solution according to claim 1 to perform etching.

12. 12. The method for manufacturing a semiconductor device according to claim 11, wherein the step includes performing recess etching by bringing the etching solution into contact with a surface of a copper-containing metal layer embedded in a via or trench formed in a semiconductor substrate.

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