Etchant for copper

Abstract

The present invention addresses the problem of providing a copper etchant capable of stably maintaining smoothness after etching. The etching agent includes hydrogen peroxide, sulfuric acid, an aromatic compound, and chloride ions, and the aromatic compound includes a structure in which a hydroxyl group and / or a carboxyl group is bonded to a benzene ring.

Description

Technical Field

[0001] The present invention relates to an etchant for copper. Background Art

[0002] In the manufacturing process of semiconductors or printed wiring boards, patterning of metals or formation of recesses is performed by wet etching. For example, in the manufacturing steps of semiconductors, trenches or recesses are formed by wet etching. In addition, in the manufacturing steps of printed wiring boards, a metal layer made of copper or the like is patterned by wet etching to form metal wirings.

[0003] In the process of forming copper wirings by a semi-additive process which is a kind of wiring formation method, a copper layer called a "seed layer" is formed on an insulating substrate by electroless plating. After forming a plating resist on the seed layer, pattern plating is performed on the resist openings on the seed layer by electroplating copper. Then, the plating resist is removed, and the seed layer remaining between the wirings is removed by wet etching to form copper wirings. In the process of removing the seed layer by wet etching, not only the seed layer but also the copper wiring portion is etched by the etchant. Therefore, this etching may affect the wiring shape or characteristics.

[0004] Regarding such an etchant for removing the seed layer, for example, it is described in Patent Documents 1 and 2.

[0005] Patent Document 1 describes an etchant which contains sulfuric acid and hydrogen peroxide, and also contains a benzotriazole compound and an amine compound. Patent Document 1 describes that this etchant can suppress undercut of copper wirings when removing the seed layer.

[0006] Patent Document 2 describes an etchant which contains sulfuric acid and hydrogen peroxide, and also contains nitrogen-containing heterocyclic compounds such as amino acids and azoles, halogens, etc. Patent Document 2 describes that this etchant can keep the surface shape of copper wirings and the like smooth even after removing the seed layer.

[0007] However, in the etching performed with the so-called sulfuric acid-hydrogen peroxide-based etchant described in Patent Documents 1 and 2, the smoothness of the etched copper surface is insufficient. Especially in the case of continuously performing etching treatment, there is a problem that it is difficult to stably maintain the smoothness after etching.

[0008] [Prior Art Documents]

[0009] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-202242

[0011] [Patent Document 2] Japanese Patent Application Laid-Open No. 2021-195572. Summary of the Invention

[0012] [Problems to be Solved by the Invention]

[0013] The present invention has been completed in view of the problems of the aforementioned prior art, and an object thereof is to provide an etchant for copper that can stably maintain the smoothness of the copper surface after etching.

[0014] [Means for Solving the Problems]

[0015] The present invention includes hydrogen peroxide, sulfuric acid, an aromatic compound, and chloride ions, and the aforementioned aromatic compound includes a structure in which a hydroxyl group and / or a carboxyl group is bonded to a benzene ring.

[0016] It may also contain 0.000020% by mass or more and 0.02% by mass or less of the aforementioned chloride ions.

[0017] The aforementioned aromatic compound may also be one or more selected from the group consisting of phenols, benzoic acid compounds, 2-hydroxybenzoic acid, 5-sulfosalicylic acid, methyl salicylate, sodium salicylate, isoamyl salicylate, and acetylsalicylic acid.

[0018] It may also further contain triazoles.

[0019] The aforementioned triazoles may also be one or more selected from the group consisting of 1,2,4-triazole, 1,2,3-triazole, 3-amino-5-mercapto-1,2,4-triazole, 3,5-diamino-1,2,4-triazole, 3,5-dimethyl-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 4-amino-1,2,4-triazole, 3-amino-1,2,4-triazole, 4-amino-3-mercapto-4H-1,2,4-triazole, and 3-amino-5-methylthio-1H-1,2,4-triazole.

[0020] [Effects of the Invention]

[0021] According to the present invention, an etchant for copper that can stably maintain the smoothness of the copper surface after etching can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a chart showing the results of analyzing the surface of the test substrate with an EDS device.

[0023] Figure 2 It is a chart showing the results of analyzing the surface of the test substrate with an EDS device.

[0024] Figure 3 It is a chart showing the relationship between the change in chloride ion concentration and the Sdr value. DETAILED DESCRIPTION OF THE INVENTION

[0025] The following describes an embodiment of an etchant for copper (hereinafter also simply referred to as an etchant) of the present invention.

[0026] The etchant for copper in this embodiment is an etchant that contains hydrogen peroxide, sulfuric acid, an aromatic compound, and chloride ions, and the aforementioned aromatic compound contains a structure in which a hydroxyl group or / and a carboxyl group is bonded to a benzene ring.

[0027] [Copper]

[0028] The copper etched with the etchant of this embodiment can be copper (pure copper) and copper alloys containing copper. Hereinafter, "copper" in this specification refers to copper or a copper alloy.

[0029] [Hydrogen peroxide]

[0030] Hydrogen peroxide functions as an "oxidizer for copper" in the etchant.

[0031] The concentration of hydrogen peroxide in the etchant is, for example, in the range of 4 mass% or more and 25 mass% or less, or 5 mass% or more and 20 mass% or less.

[0032] When the concentration of hydrogen peroxide is in the above range, it can function appropriately as an oxidizer for copper.

[0033] [Sulfuric acid]

[0034] Sulfuric acid functions as a "component for dissolving the oxidized copper" in the etchant. In the etchant, copper becomes copper oxide due to hydrogen peroxide, but this copper oxide is dissolved in the liquid due to the acid, so the copper is etched.

[0035] The sulfuric acid concentration during etching is, for example, in the range of 5 mass% or more and 30 mass% or less, or 10 mass% or more and 20 mass% or less.

[0036] When the sulfuric acid concentration is in the above range, the oxidized copper can be appropriately dissolved in the etchant.

[0037] [Aromatic compound]

[0038] The aromatic compound is a compound having a structure in which a hydroxyl group or / and a carboxyl group is bonded to a benzene ring.

[0039] In the aromatic compound of this embodiment, it is more preferable that at least one of a hydroxyl group and a carboxyl group is directly bonded to a carbon atom constituting the benzene ring.

[0040] Regarding the aromatic compound having a structure in which a hydroxyl group is bonded to a benzene ring, examples include phenols such as phenol, cresol, and xylenol. Among them, a phenol having a structure in which only a hydroxyl group is bonded to the benzene ring is more preferable.

[0041] Regarding aromatic compounds having a "structure in which a carboxyl group is bonded to a benzene ring", examples include benzoic acid, nitrobenzoic acid, aminobenzoic acid, and addition products in which other functional groups are added to benzoic acid, or salts of benzoic acid such as sodium benzoate, etc.

[0042] Regarding aromatic compounds having a "structure in which a hydroxyl group and a carboxyl group are bonded to a benzene ring", examples include 2-hydroxybenzoic acid (i.e., salicylic acid), 5-sulfosalicylic acid, methyl salicylate, sodium salicylate, isopentyl salicylate, acetylsalicylic acid, etc.

[0043] When using a "compound having a structure in which both a hydroxyl group and a carboxyl group are bonded to a benzene ring" as the aromatic compound, there is an advantage that the smoothness after etching can be maintained in a particularly preferred state.

[0044] The concentration of the aromatic compound in the etchant is, for example, in the range of 0.0001% by mass or more and 1% by mass or less, or 0.0005% by mass or more and 0.5% by mass or less, or 0.0008% by mass or more and 0.1% by mass or less.

[0045] When the concentration of the aromatic compound is in the above range, the smoothness after etching can be maintained in a more preferred state.

[0046] [Chloride ion]

[0047] Chloride ions act as "components that inhibit the etching of copper".

[0048] Chloride ions can be incorporated by including a chloride ion source in the etchant. Examples of the chloride ion source include sodium chloride, calcium chloride, aluminum chloride, magnesium chloride, ammonium chloride, etc.

[0049] The chloride ion concentration in the etchant is, for example, in the range of 0.00001% by mass or more and 0.5% by mass or less, or 0.000015% by mass or more and 0.05% by mass or less, or 0.00002% by mass or more and 0.02% by mass or less.

[0050] When the chloride ion concentration is in the above range, the etching rate of copper can be appropriately inhibited, and it is easy to adjust the etching performance to a more preferred range.

[0051] [Triazoles]

[0052] The etchant of this embodiment may further contain triazoles.

[0053] In this embodiment, triazoles refer to 1,2,3-triazole, 1,2,4-triazole, and derivatives in which various functional groups are bonded to the triazole skeleton.

[0054] The triazole skeleton refers to a compound containing a "5-membered nitrogen-containing heterocycle containing 3 nitrogen atoms".

[0055] Examples of the aforementioned derivatives include compounds in which an alkyl group such as an amino group, a mercapto group, a methyl group, or an ethyl group is bonded to a triazole skeleton.

[0056] Among them, triazole derivatives bonded with an amino group or a mercapto group are more preferred.

[0057] More specifically, examples include 1,2,3-triazole, 1,2,4-triazole, 3-amino-5-mercapto-1,2,4-triazole, 3,5-diamino-1,2,4-triazole, 3,5-dimethyl-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 4-amino-1,2,4-triazole, 3-amino-1,2,4-triazole, 4-amino-3-mercapto-4H-1,2,4-triazole, 3-amino-5-methylthio-1H-1,2,4-triazole, etc.

[0058] The concentration of triazoles in the etchant is, for example, in the range of 0.00001% by mass or more and 1.0% by mass or less, or 0.00005% by mass or more and 0.5% by mass or less, or 0.00009% by mass or more and 0.48% by mass or less.

[0059] When the concentration of triazole is in the above range, it is easy to maintain a more preferred state of smoothness after etching. In addition, by including triazole, it is easy to improve the etching performance for electroless copper-plated copper. Therefore, an etchant suitable for "removing the seed layer obtained by the semi-additive method so that it does not remain in parts other than the wiring" can be obtained.

[0060] [Other Components]

[0061] In the etchant of the present embodiment, other additives may also be added as required. Examples of other components include additives that improve the solubility of each component, additives that similarly inhibit the decomposition of each component, a copper ion source as a "copper oxidation promoting component for metallic copper", a pH adjuster, a surfactant, and the like.

[0062] For example, when including a copper ion source belonging to a "copper oxidation promoting component for metallic copper", examples of the copper ion source include copper sulfate, copper salts of organic acids, and the like.

[0063] When including a copper ion source, its content is more preferably about 1.4% by mass or more and 4.2% by mass or less.

[0064] In addition, the pH of the etchant of the present embodiment is not particularly limited, and ranges such as pH 3 or less or pH 2 or less can be cited.

[0065] [Solvent]

[0066] An etchant can be easily prepared by dissolving the foregoing components in a suitable solvent such as ion-exchanged water, pure water, or ultrapure water.

[0067] Regarding the components of the etchant, unless otherwise specified, the exemplified components can be used alone or in combination of two or more.

[0068] The etchant of this embodiment can be manufactured by mixing the above components according to publicly known methods.

[0069] In addition, regarding each component, considering solubility and decomposability, some components can be mixed first, and then all components can be mixed immediately before use. Or, a concentrated solution mixed with some solvents can be prepared first, and then the remaining solvents can be mixed immediately before use to prepare an etchant with an appropriate concentration.

[0070] The method of etching copper with the etchant of this embodiment is not particularly limited and can be used according to publicly known methods. Examples of the method include etching treatment by dipping, spraying, etc. The treatment conditions such as treatment temperature and treatment time can also be adjusted appropriately.

[0071] For example, in the case of etching by spraying, it can be cited as follows: the spraying pressure is 0.05 to 0.20 MPa, the liquid temperature is 20°C or higher and 35°C or lower, and the treatment time is 20 seconds or longer and 300 seconds or shorter.

[0072] In addition, in the case of etching by dipping, it can be cited as follows: the liquid temperature is 20°C or higher and 35°C or lower, and the treatment time is 20 seconds or longer and 300 seconds or shorter.

[0073] Regarding the index showing the smoothness of the copper surface etched with the etchant of this embodiment, for example, it can be evaluated according to the following index.

[0074] The developed area ratio (Sdr) value of the interface measured according to ISO25178 can be, for example, 0.20% or less, more preferably 0.18% or less, and even more preferably 0.175% or less.

[0075] The Sdr value represents the degree of increase of the "developed area (surface area) of the measured surface" relative to the "area of the measured surface". The smaller this value, the smoother the surface. This value can be measured, for example, by a publicly known shape analysis laser microscope. Specifically, it can be measured according to the method described in the following examples.

[0076] In addition, the arithmetic mean roughness (Ra) measured according to JIS B 0601 (2013) can be, for example, 0.11 μm or less, or 0.10 μm or less, or 0.095 μm or less.

[0077] In addition, the root mean square roughness (Rq) measured according to JIS B 0601 (2013) can be, for example, 0.125 μm or less, more preferably 0.120 μm or less.

[0078] Both Ra and Rq are standards for showing the roughness of the surface shape, and the smaller the value, the less uneven (smoother) the surface is.

[0079] This value can be measured, for example, using a publicly known laser microscope. Specifically, it is measured by the method described in the following examples.

[0080] The copper treated with the etchant of this embodiment is not particularly limited, and is particularly suitable for removing the seed layer in the process of forming copper wiring by the semi-additive method.

[0081] In this case, a seed layer is formed on an insulating substrate by electroless copper plating belonging to the copper layer. After forming a plating resist on the seed layer, a resist opening on the seed layer is pattern-plated by electrolytic copper plating. Then, the plating resist is removed and wiring is formed, and the seed layer remaining between the wirings is wet-etched with the etchant of this embodiment to remove it, whereby wiring can be formed.

[0082] In addition, in such wiring formation, the copper surface of the wiring can be made smooth and an appropriate wiring shape with few dents (lateral etching) of the wiring can be maintained.

[0083] By maintaining the smoothness of the copper surface such as the wiring in this way, there is an advantage that the transmission loss of the electrical signal can be reduced.

[0084] In addition, the etchant of this embodiment has etching performance suitable for removing the seed layer. For example, compared with the etching rate of the copper layer formed by electrolytic copper plating, the etching rate of the copper layer formed by electroless copper plating is faster. Therefore, the seed layer removal property is high and the lateral etching of the wiring is less, and it is suitable for removing the seed layer in the wiring formation step.

[0085] In addition, even if the etching treatment is continuously performed, the etchant of this embodiment can suppress the reduction of the smoothness of the treated copper surface. Therefore, a copper surface with high smoothness can be stably obtained.

[0086] In the etching for removing the seed layer in the general process of forming copper wiring by the semi-additive method, it is known that chloride ions contained in the copper plating of the wiring or the seed layer will mix into the etchant, so the chloride ion concentration in the etchant becomes higher as the number of treatments increases. In a sulfuric acid hydrogen peroxide-based etchant, when chloride ions are contained in an appropriate concentration range in the etchant, there is an effect of appropriately suppressing etching and maintaining an appropriate etching rate. However, if the concentration rises excessively, the etching property may be extremely reduced, and copper cannot be sufficiently removed or the smoothness after etching may be reduced.

[0087] The etchant of this embodiment can suppress the reduction of etching performance even when the chloride ion concentration increases, and a copper surface with high smoothness can be stably obtained.

[0088] Therefore, even when a large number of substrates or other objects to be processed are continuously processed, a copper surface with high smoothness can be stably obtained.

[0089] The etchant of this embodiment is as described above, but it should be understood that all features of the embodiments disclosed this time are illustrative and not restrictive. The scope of the present invention is not as described above, but is represented by the scope of the patent application, and is intended to include meanings equivalent to the scope of the patent application and all changes within its scope.

[0090] [Examples]

[0091] Examples are shown below to more specifically illustrate the present invention, but the present invention is not limited to these examples.

[0092] [Test 1: Smoothness test]

[0093] (Etchant)

[0094] Prepare each etchant used in this example.

[0095] Each etchant is an aqueous solution prepared by dissolving the following materials in ion-exchanged water as a solvent so as to have the concentrations of the respective components shown in Tables 1 to 3. In addition, the masses of the respective components are also shown in Tables 1 to 3, but ion-exchanged water is added in such a way that the total amount becomes 1000 g in addition to the components in the tables. In addition, according to the adjustment method described later, 100 g of hydrogen peroxide is added in addition to the components described in Tables 1 to 3 and the etchant is finally adjusted to 1100 g.

[0096] (Materials)

[0097] Sulfuric acid: manufactured by Nissan Chemical Industries, Ltd., refined sulfuric acid

[0098] Copper sulfate: manufactured by Meltex

[0099] Triazoles

[0100] 3,5-Diamino-1,2,4-triazole: manufactured by Tokyo Chemical Industry Co., Ltd.

[0101] 1,2,4-Triazole: manufactured by Fujifilm wako pure chemical corporation

[0102] 3-Amino-5-mercapto-1,2,4-triazole: manufactured by Tokyo Chemical Industry Co., Ltd.

[0103] 3-Mercapto-1,2,4-triazole: manufactured by Otsuka Chemical Co., Ltd.

[0104] 3-Amino-1H-1,2,4-triazole: manufactured by Fujifilm Wako Pure Chemical Corporation 4-Amino-3-mercapto-4H-1,2,4-triazole: manufactured by Fujifilm Wako Pure Chemical Corporation

[0105] 3-Amino-5-methylthio-1H-1,2,4-triazole: manufactured by Tokyo Chemical Industry Co., Ltd.

[0106] 3,5-Dimethyl-1,2,4-triazole: manufactured by Tokyo Chemical Industry Co., Ltd.

[0107] azole

[0108] 5-Aminotetrazole: manufactured by Tokyo Chemical Industry Co., Ltd.

[0109] Benzotriazole: manufactured by KISHIDA CHEMICAL Co., Ltd.

[0110] Aromatic compound

[0111] 2-Hydroxybenzoic acid (i.e., salicylic acid): manufactured by Fujifilm Wako Pure Chemical Corporation

[0112] Phenol: manufactured by Fujifilm Wako Pure Chemical Corporation

[0113] Benzoic acid: manufactured by Tokyo Chemical Industry Co., Ltd.

[0114] 5-Sulfosalicylic acid dihydrate: manufactured by Tokyo Chemical Industry Co., Ltd.

[0115] Methyl salicylate: manufactured by Fujifilm Wako Pure Chemical Corporation

[0116] Acetylsalicylic acid: manufactured by Fujifilm Wako Pure Chemical Corporation

[0117] Amino acid

[0118] β-Alanine: manufactured by Fujifilm Wako Pure Chemical Corporation

[0119] Hydrogen peroxide: manufactured by ADEKA Corporation

[0120] Method for adjusting an etchant. After mixing sulfuric acid, an aromatic compound or an amino acid in ion-exchanged water (DI water), mix a triazole or an azole and dissolve them sufficiently, and then mix copper sulfate as a copper ion source. Immediately before etching, mix hydrogen peroxide.

[0121] (Test substrate)

[0122] Fabricate the following test substrates 1 and 2.

[0123] Substrate 1: On a copper-clad laminate (CCL) with a thickness of 0.2 mm and dimensions of 340×510 mm, a plating layer (20 μm) is formed using an electrolytic copper plating solution. Based on this, a substrate is fabricated and cut into 100×100 mm.

[0124] Substrate 2: On a wafer with a thickness of 725 μm and a diameter of 200 mm, an insulating resin (25 μm) is laminated. On the insulating resin, a seed layer (0.4 μm) is formed using an electroless copper plating solution. Then, on the seed layer, a pattern layer with a thickness of 6 μm and L / S = 10 / 10 μm is formed using an electrolytic copper plating solution. Based on this, a substrate is fabricated and cut into 10×10 mm.

[0125] (Test method)

[0126] Etch Substrate 1 using each etchant.

[0127] The processing conditions are as follows.

[0128] Using a sprayer, spray each etchant at a temperature of 25°C with a spray pressure of 0.1 MPa onto the substrate, and adjust the etching time to etch the substrate in such a way that the etching amount of copper becomes 1.0 μm. Then, perform water washing and drying.

[0129] (Evaluation method)

[0130] Evaluate the etched test substrates according to the following method.

[0131] (1) Measurement of the spreading area ratio (Sdr) value of the interface

[0132] The spreading area ratio (Sdr) of the interface is measured by a confocal microscope. Using a confocal microscope (manufactured by Lasertec Corporation, OPTELICS HYBRID+), measure the Sdr value using an objective lens with a magnification of 50 times.

[0133] (2) Measurement methods for arithmetic mean roughness (Ra) and root mean square roughness (Rq)

[0134] The arithmetic mean roughness (Ra) and root mean square roughness (Rq) are measured by a confocal microscope. Using a confocal microscope (measurement device: OPTELICS HYBRID+, manufactured by Lasertec Corporation), measure using an objective lens with a magnification of 50 times. The measurement of arithmetic mean roughness and root mean square roughness is carried out in accordance with the standard (JIS B 0633:2001).

[0135] The results are shown in Tables 1 to 3.

[0136] [Table 1]

[0137]

[0138] [Table 2]

[0139]

[0140] [Table 3]

[0141]

[0142] In each of the examples shown in Tables 1 to 3, the Sdr value is 0.20% or less, the Ra is 0.11 μm or less, and the Rq is in the range of 0.125 μm, and the smoothness is superior to that of the etched comparative example (Comparative Example 1 is an untreated control group).

[0143] [Test 2: Evaluation of Cu residue]

[0144] In the above examples, the etchant of Examples 1 and 8 (adding 100 g of hydrogen peroxide to the components in the table) and the substrate 2 were used, and the treatment time was adjusted so that the etching amount of copper in the pattern layer of the substrate 2 became 0.5 μm for treatment, and the copper residue after etching was investigated.

[0145] For the evaluation, three points were arbitrarily selected on the surface of the resin portion between the patterns of the test substrate after etching, and the surface was analyzed by an EDS (Energy dispersive X-ray spectrometry) device. The device used was JSM-IT200A (manufactured by JEOL Ltd.), and the analysis was performed at an acceleration voltage of 10 kv.

[0146] The result of one of the three measured points is shown in Figure 1 and Figure 2 .

[0147] Figure 1 As a result of etching with the etchant of Example 1 containing triazole, peaks were observed at positions where C, Si, and O derived from the insulating resin were shown between the patterns, but no peak appeared at the position where Cu was shown.

[0148] On the other hand, Figure 2 As a result of etching with the etchant of Example 8 not containing triazole, peaks were observed at positions where C, Si, and O derived from the insulating resin were shown between the patterns, and in addition, peaks were also observed at the positions where Cu was shown. In addition, the same results were obtained for the other two points.

[0149] It can be seen from this that the test substrate treated with the etchant of the embodiment containing triazole has good smoothness and low residual copper in the seed layer.

[0150] [Experiment 3: Influence of chloride ion concentration]

[0151] Using DI water as a solvent, an etchant was prepared by adjusting to the concentrations of the respective components shown in Table 4.

[0152] Since the copper-plated substrate was etched for a long time, it was predicted that chloride ions would dissolve into the etchant. Based on the above etchant as a matrix, 14 kinds of etchants were formed by changing the chloride ion concentration between 0.25 mg / L and 100 mg / L, and substrate 1 was etched with these etchants. The etching conditions were the same as those in Experiment 1 above. In addition, 100 g of hydrogen peroxide was added to the components in the table in the same manner as in Experiment 1 to prepare an etchant.

[0153] The Sdr value after etching was measured in the same manner as in Experiment 1, and the results are shown in Table 5 and Figure 3 .

[0154] In addition, regarding the etching rate, the weight of the substrate was measured before and after etching and divided by the value obtained by multiplying the area of the substrate by the etching time, and this was calculated as μm / minute.

[0155] It is also shown in Table 5.

[0156] [Table 4]

[0157]

[0158] [Table 5]

[0159]

[0160] As shown in Table 5 and Figure 3 the chart, if the chloride ion concentration increases, the Sdr value also increases, but even when the chloride ion concentration increases to 100 mg / L, the Sdr value is still below 0.2. In addition, the etching rate is also relatively stable.

Claims

1. A copper etchant, which comprises hydrogen peroxide, sulfuric acid, an aromatic compound, and chloride ions, wherein, The aforementioned aromatic compound contains a structure in which a hydroxyl group and / or a carboxyl group is bonded to a benzene ring.

2. The copper etchant according to claim 1 contains 0.000020% by mass or more and 0.02% by mass or less of the aforementioned chloride ions.

3. The copper etchant according to claim 1, wherein, The aforementioned aromatic compound is one or more selected from the group consisting of phenols, benzoic acid compounds, 2-hydroxybenzoic acid, 5-sulfosalicylic acid, methyl salicylate, sodium salicylate, isoamyl salicylate, and acetylsalicylic acid.

4. The copper etchant according to claim 1 further contains triazoles.

5. The copper etchant according to claim 4, wherein, The aforementioned triazoles are one or more selected from the group consisting of 1,2,4-triazole, 1,2,3-triazole, 3-amino-5-mercapto-1,2,4-triazole, 3,5-diamino-1,2,4-triazole, 3,5-dimethyl-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 4-amino-1,2,4-triazole, 3-amino-1,2,4-triazole, 4-amino-3-mercapto-4H-1,2,4-triazole, and 3-amino-5-methylthio-1H-1,2,4-triazole.

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