JP2005330572A - Etchant, replenishment solution and method for producing copper wiring using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a fine and dense wiring pattern with reduced undercut, and to produce a printed circuit board at a high yield using the same. <P>SOLUTION: The etchant for copper and copper alloys includes an aqueous solution containing 14 to 155 g/liter of cupric ion source as oxidizing metal ion source in terms of a concentration of copper ions; 7 to 180 g/liter of hydrochloric acid; and 0.1 to 50 g/liter of azole, the azole including nitrogen atoms only as heteroatoms residing in a ring. The method for producing a wiring by etching of copper or copper alloys, includes the step of: etching a portion of a copper layer on an electrical insulative member (1) that is not covered with an etching resist (3) using the above-described etchant so as to form the wiring (2). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an etching agent and replenisher for copper or copper alloy, and a method of manufacturing a wiring using the same.

  In the production of a printed wiring board, when a copper wiring is formed by a photoetching method, an iron chloride-based etching agent, a copper chloride-based etching agent, an alkaline etching agent, or the like is used as an etching agent. However, these etching agents have a problem that copper under an etching resist called undercut dissolves. In particular, when the wiring pattern is fine, the undercut must be minimized.

Conventionally, the etching agent which suppressed the said undercut has been examined. For example, Patent Document 1 below proposes an aqueous solution containing cupric chloride, hydrochloric acid, a 2-aminobenzothiazol compound, polyethylene glycol, and a polyamine compound.
Japanese Patent No. 3387528

  However, the conventional etching agent may not be sufficient to suppress undercut, and there is a need for an etchant that further suppresses undercut.

  As a result of intensive studies to solve the above problems, the inventors of the present invention can suppress pattern undercut when a specific amount of a specific azole is added to an etchant having an oxidizing metal ion source as an oxidizing agent. The present invention has been completed.

That is, the etching agent of the present invention is an etching agent of copper or copper alloy,
An oxidizing metal ion source having a metal ion concentration of 14 to 155 g / liter,
7 to 180 g / liter of at least one acid selected from inorganic acids and organic acids;
It consists of the aqueous solution which contains the azole which has only a nitrogen atom as a different atom in a ring in the range of 0.1-50 g / liter.

  The etching agent may further contain at least one selected from a cationic surfactant, glycol and glycol ether.

The replenisher of the present invention is a replenisher that is added to the etchant when the etchant of the present invention is used repeatedly,
7 to 360 g / liter of at least one acid selected from inorganic acids and organic acids;
It consists of the aqueous solution which contains the azole which has only a nitrogen atom as a different atom in a ring in the range of 0.1-50 g / liter.

  The method of manufacturing a wiring of the present invention is a method of manufacturing a wiring by etching copper or a copper alloy, and etches a portion of the electrical insulating material that is not covered with an etching resist by using the above-described etching agent. And forming a wiring.

  When a wiring pattern is formed using the etching agent of the present invention, a fine and high-density wiring pattern can be formed because there is little undercut. Therefore, for example, when applied to the manufacture of a printed wiring board, it can be manufactured with a high yield. In addition, when the etching agent of the present invention is used repeatedly, if the replenisher of the present invention is added to the etching agent, each component ratio of the etching agent is maintained appropriately, so that the wiring pattern with less undercut is stable. Can be formed.

  The etching agent of the present invention is an acidic type etching agent mainly composed of an oxidizing metal ion source and an acid.

  Examples of the oxidizing metal ion source include a cupric ion source such as a cupric salt and a ferric ion source such as a ferric salt. Specific examples of the cupric ion source include copper chloride, copper sulfate, copper bromide, organic acid copper salts, copper hydroxide, and the like. Specific examples of the ferric ion source include iron chloride, iron bromide, iron iodide, iron sulfate, iron nitrate, and iron salts of organic acids. Among the oxidizing metal ion sources, it is preferable to use a cupric ion source from the viewpoint of etching rate stability. In particular, the use of copper chloride (cupric chloride) is preferable because the etching rate is increased.

  The concentration of the oxidizing metal ion source is 14 to 155 g / liter, preferably 33 to 122 g / liter in terms of metal ion concentration. If the concentration is too low, the etching rate decreases. On the other hand, when too high, it will become difficult to melt | dissolve and an etching rate will become unstable. When cupric chloride is used as the oxidizing metal ion source, the concentration of cupric chloride is 30 to 330 g / liter, preferably 70 to 260 g / liter.

  The etching agent of the present invention contains at least one acid selected from inorganic acids and organic acids. The concentration of the acid is 7 to 180 g / liter, preferably 18 to 110 g / liter. If the acid concentration is too low, a stable etching rate cannot be obtained. If the acid concentration is too high, the copper dissolution stability is lowered, or reoxidation occurs on the copper surface. Examples of the inorganic acid include sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid and the like. Examples of the organic acid include formic acid, acetic acid, oxalic acid, maleic acid, benzoic acid, and glycolic acid. Among the acids, hydrochloric acid is preferable from the viewpoints of etching rate stability and copper dissolution stability.

  In the etching agent of the present invention, an azole having only a nitrogen atom as a different atom in the ring is added in order to suppress undercut. The azole may be a monocyclic compound or a compound in which a ring is condensed. In particular, an imidazole compound, a triazole compound, or a tetrazole compound is preferable, and two or more of these azoles may be used in combination.

  Examples of the imidazole compound include alkyl imidazoles such as imidazole, 2-methylimidazole, 2-undecyl-4-methylimidazole, 2-phenylimidazole, benzimidazole, 2-methylbenzimidazole, 2-undecylbenzimidazole, Benzimidazoles such as 2-phenylbenzimidazole and 2-mercaptobenzimidazole may be mentioned. Of these, benzimidazole is preferred.

  Examples of the triazole compound include 1,2,3-triazole, 1,2,4-triazole, 5-phenyl-1,2,4-triazole, 5-amino1,2,4-triazole, benzotriazole, Examples include 1-methyl-benzotriazole and tolyltriazole. Of these, benzotriazole is preferred.

Examples of the tetrazole compounds include 1H-tetrazole, 5-amino-1H-tetrazole, 5-methyl-1H-tetrazole, 5-phenyl-1H-tetrazole, 5-mercapto-1H-tetrazole, 1-phenyl-5 Mercapto-1H-tetrazole, 1-cyclohexyl-5-mercapto-1H-tetrazole, 5,5′-bis-1
H-tetrazole is mentioned. Among these, 5-methyl-1H-tetrazole, 5-phenyl-1H-tetrazole and 5-amino-1H-tetrazole are preferable, and 5-phenyl-1H-tetrazole and 5-amino-1H-tetrazole are particularly preferable.

  The concentration of the azole is 0.1 to 50 g / liter, preferably 0.1 to 15 g / liter, and more preferably 0.2 to 10 g / liter. If the concentration is too low, the undercut is not sufficiently suppressed, and if it is too high, the etching rate decreases.

  The etching agent of the present invention comprises at least one selected from a cationic surfactant, glycol and glycol ether in order to improve the stability of the liquid, perform uniform etching, and make the surface shape after etching uniform. It may be included. Examples of the cationic surfactant include alkyl quaternary ammonium salts such as benzalkonium chloride and alkyltrimethylammonium chloride. Examples of the glycol include ethylene glycol, diethylene glycol, propylene glycol, and polyalkylene glycol. Examples of the glycol ether include propylene glycol monoethyl ether, ethylene glycol monobutyl ether, 3-methyl-3-methoxybutanol, dipropylene glycol methyl ether, and diethylene glycol butyl ether.

  In the etching agent of the present invention, methanol, ethanol, 1-propanol, 2-propanol, butanol, in order to improve the stability of the liquid, perform uniform etching, and make the surface shape after etching uniform, Solvents such as alcohols such as benzyl alcohol, amides such as N, N-dimethylformamide, dimethylimidazolidinone and N-methylpyrrolidone, sulfoxides such as dimethyl sulfoxide, fatty acid salts, alkyl sulfate esters, alkyl phosphoric acids, etc. Nonionic surfactants such as polyoxyethylene alkyl ether, polyoxypropylene alkyl ether, block polymer of polyoxyethylene and polyoxypropylene, lauryldimethylaminoacetic acid betaine, stearyl dimethyl Acid betaine, lauryl dimethylamine oxide, betaines such as lauryl hydroxy sulfobetaine, such as amphoteric surfactants such as amino acids, may be added various additives as necessary.

The etching agent of the present invention can be easily prepared by dissolving the above-described components in water. The water is preferably water from which ionic substances and impurities such as ion-exchanged water, pure water, and ultrapure water have been removed.

  In the case of etching copper or copper alloy with the etching agent of the present invention using an etching apparatus, for example, after preparing all the components of the etching agent to have a predetermined composition, it may be supplied to the etching apparatus, Each component of the etching agent may be separately supplied to the etching apparatus, and the components may be mixed in the etching apparatus so as to have a predetermined composition, and a part of the components of the etching agent may be mixed in advance. Then, the components may be supplied to the etching apparatus, and further components may be supplied to the etching apparatus to mix the components of the etching agent so as to have a predetermined composition. In addition, when supplying each component of the etching agent to the etching apparatus, the concentration of each component is not particularly limited. For example, the high concentration of each component is supplied to the etching apparatus, and water is used in the etching apparatus. May be diluted to a predetermined concentration.

  The replenisher of the present invention is a replenisher that is added to the etchant when the etchant of the present invention is used repeatedly, and contains at least one acid selected from inorganic acids and organic acids in an amount of 7 to 360 g / liter, Preferably, it contains 30 to 360 g / liter and an azole having only a nitrogen atom as a hetero atom in the ring in a range of 0.1 to 50 g / liter, preferably 0.2 to 30 g / liter. By adding the replenisher, each component ratio of the etchant is maintained appropriately, so that a wiring pattern with less undercut can be stably formed. Of the acids, hydrochloric acid is preferred from the viewpoint of copper dissolution stability. The replenisher of the present invention may further contain an oxidizing metal ion source such as cupric chloride in a range not exceeding a metal ion concentration of 14 g / liter.

  The method of using the etching agent of the present invention is not particularly limited. For example, the method of spraying the etching agent on a portion of the copper layer on the insulating material that is not covered with the etching resist, Examples thereof include a method of applying a film and a method of immersing an object to be etched in the etching agent. Further, before the treatment with the etching agent of the present invention, the surface of copper or copper alloy may be previously wetted with water, low-concentration hydrochloric acid, the replenishing solution, or the like in order to improve the wettability of the etching agent. Also, when using a cupric ion source as the oxidizing metal ion source, the cuprous ions generated in the treatment agent by copper etching are oxidized back to cupric ions to restore the etching ability. In addition, a gas such as air containing at least one of oxygen and ozone may be blown into the etching agent by bubbling or an oxidizing agent such as hydrogen peroxide may be added. Further, for example, the produced cuprous ions may be oxidized by means disclosed in Japanese Patent Application Laid-Open No. 7-243062, Japanese Patent No. 2684492, Japanese Patent No. 3220564, and the like. In addition, as for the temperature of the etching agent when etching copper, 30-50 degreeC is preferable.

  When etching copper or a copper alloy by spraying using the etching agent of the present invention, the etching agent is preferably maintained at a temperature of 30 to 50 ° C. and a spray pressure of 0.03 to 0.3 MPa. Thereby, an etching rate will be 0.1-0.7 micrometer / s, and suppression of an undercut will become easy. Moreover, what is necessary is just to set suitably about other conditions, such as the flow volume of a spray, and the striking force of the spray in the surface of copper or a copper alloy. Furthermore, when using a spray etching apparatus, the type and arrangement of the spray nozzle, the conditions for swinging the spray nozzle, the distance between the spray nozzle and the surface of the etching object, the type and arrangement of the roll, etc. may be set as appropriate. . For example, it is a preferable example to dispose the spray nozzle between the spray nozzle and the object to be etched so that an obstacle that blocks the spray is not disposed. For example, in order to improve the uniformity of etching, an air discharge nozzle or an air knife may be installed in the spray etching apparatus (see JP 2000-328267 A).

  When etching an object to be etched in the etching agent of the present invention to etch copper or a copper alloy, for example, in order to improve etching uniformity, the etching agent is jetted into an immersion tank storing the etching agent. A nozzle may be installed (see, for example, Japanese Utility Model Laid-Open No. 2-136359).

  When the etching agent of the present invention is repeatedly used, the above-described replenisher is added to the etching agent to maintain the copper ion concentration in the etching agent at 155 g / liter or less, preferably 122 g / liter or less. However, it is preferable to etch copper or a copper alloy. Thereby, precipitation of a copper crystal can be prevented. Moreover, about the density | concentration of a cuprous ion among the said copper ions, it is preferable to etch, maintaining at 2.50 g / liter or less, and it is more preferable to etch, maintaining at 1.20 g / liter or less. When the concentration of cuprous ions is too high, the etching rate decreases. In the case where a cupric ion source is used as the oxidizing metal ion source and an oxidizing agent such as hydrogen peroxide is used to restore the etching ability, the concentration of cuprous ions is 0.01 to 2.50 g. Etching is preferably carried out while maintaining in the range of 0.1 / liter, more preferably etching while maintaining in the range of 0.15 to 1.20 g / liter. In this case, if the concentration of cuprous ion is too low, the suppression of undercut tends to be insufficient. In addition, it is preferable to measure the density | concentration of a copper ion by a titration method, an electrical conductivity method, etc.

  When the etching agent of the present invention is used repeatedly, the concentration of each component in the etching agent can be managed by, for example, an etching agent management system proposed in Japanese Patent Application Laid-Open No. 2001-348685. . In addition, in the etching agent management system proposed in the above publication, a conductivity meter, a potentiostat device, a titration analyzer, etc. are installed in place of the pH sensor and the ORP sensor, etc. The concentration can also be controlled.

  When copper or a copper alloy is etched using the etching agent of the present invention, for example, copper chloride, copper oxide, copper hydroxide, the azole, a complex of the azole and copper, or the like remains in the etched portion. There is. For example, when using the etching agent of the present invention to form a copper wiring by etching a portion of copper that is not covered with the etching resist, and manufacturing a printed wiring board, the component of the etching agent is present on the side surface of the copper wiring. If it remains, the electrical insulation reliability of the printed wiring board will decrease. Therefore, when manufacturing printed wiring boards and the like that require long-term electrical insulation reliability, after etching copper or a copper alloy, the etched portion is cleaned with a cleaning solution that dissolves the components of the etching agent. Is preferred. As a result, the component of the etching agent remaining on the side surface of the wiring and the like is removed, so that it is possible to prevent a short circuit between the wirings and poor adhesion of the solder resist due to the component. Here, the cleaning liquid is preferably at least one solution selected from an acidic solution, a solution containing a substance that forms a complex compound with metal ions in the etching agent, and an organic solution. When cleaning with an acidic solution or a solution containing a substance that forms a complex compound with metal ions in the etching agent, in particular, an oxidizing metal ion source in the etching agent, cuprous chloride generated by the reaction, oxidation Residual components such as copper can be effectively removed. In the case of washing with an organic solution, particularly the residual component of azole in the etching agent can be effectively removed.

  In the case where an acidic solution is used as the cleaning solution, it is preferable to adjust the pH to 4 or less using a mixed solution of hydrogen peroxide and sulfuric acid, hydrochloric acid, or the like. The temperature of the cleaning liquid in this case is preferably 15 to 50 ° C., and the cleaning method is preferably spray cleaning, ultrasonic cleaning, immersion cleaning or the like. Moreover, when using the solution containing the substance which forms a complex compound with the metal ion in the etching agent as the cleaning solution, for example, an aqueous solution containing 20 to 200 g / liter of ammonia, monoethanolamine or the like is used. It is preferable to do this. The temperature of the cleaning liquid in this case is preferably 15 to 50 ° C., and the cleaning method is preferably spray cleaning or ultrasonic cleaning. Further, when an organic solution is used as the cleaning solution, dipropylene glycol monomethyl ether or the like is preferably used, and a mixed solution of these organic solution and water is also preferable. The temperature of the cleaning liquid in this case is preferably 15 to 50 ° C., and the cleaning method is preferably spray cleaning or ultrasonic cleaning.

  Further, when cleaning with the cleaning liquid, it is preferable to perform the cleaning immediately after forming the copper wiring with the etching agent of the present invention and then removing the etching resist. Moreover, after preparing the liquid mixture which mixed the said washing | cleaning liquid and the peeling liquid of the etching resist and forming copper wiring with the etching agent of this invention, peeling of the etching resist and the said washing | cleaning were simultaneously performed with the said liquid mixture. Also good. In addition, after the etching resist is stripped, when the stripping solution remaining with the neutralizing solution is neutralized and removed, the cleaning solution may be added to the neutralizing solution, and the neutralization and the cleaning may be performed simultaneously.

  The etching agent of the present invention is particularly useful for producing a printed wiring board in which a copper wiring pattern is formed by etching. For example, an etching resist is formed on a copper foil, an electroless copper plating film, an electrolytic copper plating film, a copper sputtering film, a multilayer film thereof, etc. on an insulating base material, and the copper not covered with the etching resist is etched. This is useful when forming a wiring pattern. At this time, the thickness of the copper or copper alloy layer is appropriately set according to the use of the printed wiring board. However, when forming a fine wiring, the thickness of the copper or copper alloy layer is preferably 12 μm or less. Further, the thickness of the etching resist is preferably 40 μm or less, and more preferably 10 μm or less. If the thickness of the etching resist is too thick, the etching rate decreases. Examples of the printed wiring board include a rigid board, a flexible board, a metal core board, and a ceramic board. Examples of the etching resist include those made of a resin called dry film and liquid resist, and those made of one or more layers of metals such as nickel and nickel / gold.

  In addition, when the thickness of the etching resist is thin, it is preferable to use an etching resist having a high mechanical strength so that the etching resist is not damaged by spraying force when spraying the etching agent. Moreover, it is preferable to use what has high adhesiveness with the copper or copper alloy etched as said etching resist. In addition, the copper or copper alloy coated with the etching resist improves the adhesion with the etching resist, for example, mechanical polishing by buff polishing, scrub polishing, etc., organic acid etching agent (for example, MEC Co., Ltd.) Manufactured by CZ-8100), a persulfate-based etching agent, or the like, and preferably subjected to surface treatment by blackening treatment or the like. Thereby, peeling of the etching resist during the etching process can be prevented, and the shape of the formed wiring can be adjusted.

  When etching the etching object in which the etching resist is patterned on the copper or copper alloy layer using the etching agent of the present invention, the thickness (T) of the copper or copper alloy layer and the space (S )) (T / S) is preferably 0.5 to 1.6. It is because an undercut can be suppressed more easily. For example, when the thickness of the copper or copper alloy layer is 8 μm, the space of the etching resist is preferably 5 to 16 μm. The space of the etching resist refers to the interval between the lines in the pattern formed by the etching resist.

  Moreover, the etching agent of the present invention is particularly useful for the production of copper wiring of a substrate on which a semiconductor chip such as a CSP substrate, TAB substrate, build-up substrate or the like is directly mounted.

When the etching agent of the present invention is used in the wiring pattern forming method as described above, since there is little undercut, for example, a copper wiring having an etching factor exceeding 5 can be formed. Even when the copper or copper alloy layer is thick (for example, 18 μm or more), a copper wiring having a line pitch of 60 μm or less can be formed. Thereby, a printed wiring board having a fine and dense wiring pattern can be manufactured with a high yield. The etching factor is 2T / (W ₂ −W ₁ ) where the thickness (height) of the copper wiring is T, the width of the top of the copper wiring is W ₁ , and the width of the base of the copper wiring is W _2. The value calculated by.

FIG. 1 is a cross-sectional view showing a wiring portion in a printed wiring board according to an embodiment of the present invention. 1 is a so-called glass epoxy base material in which a glass fiber fabric is impregnated with an epoxy resin, a so-called phenol paper base material in which paper is impregnated with a phenol resin, a so-called aramid epoxy base material in which an aramid fiber nonwoven fabric is impregnated with an epoxy resin, a polyimide film A substrate such as a ceramic substrate. 2 is a copper wiring. 3 is a resist resin. In the present invention, the difference (W ₂ −W ₁ ) between the width (W ₂ ) of the base and the width (W ₁ ) of the top can be reduced.

  Hereinafter, the present invention will be specifically described with reference to examples. In addition, this invention is limited to a following example and is not interpreted.

(Examples 1-9 and Comparative Examples 1-3)
The components shown in Tables 1 and 2 were mixed to prepare the etching agents of Examples 1 to 9 and Comparative Examples 1 to 3. The etching agent of Example 1 had a specific gravity (40 ° C.) of 1.13 and an oxidation-reduction potential of 550 mV. On the other hand, a copper-clad laminate (substrate for printed wiring board) with a 12 μm thick copper foil attached to a glass epoxy substrate (GEA-67N manufactured by Hitachi Chemical Co., Ltd.) is prepared, and a 15 μm thick dry film is prepared on this. A resist (SUNFORT SPG-152 manufactured by Asahi Kasei) was pasted to form a wiring pattern of line and space = 25 μm / 25 μm (the line width was 25 μm and the gap between the lines was 25 μm). Next, the etching agent shown in Tables 1 and 2 was sprayed under the conditions of 40 ° C. and a spray pressure of 0.15 MPa to etch the copper foil, thereby forming a copper wiring pattern. Next, the dry film resist was peeled off by spraying a 3 wt% sodium hydroxide aqueous solution.

The obtained laminated board is cut, the cross-sectional shape shown in FIG. 1 of the formed wiring pattern is observed, and the difference (W ₂ −W) between the width (W ₂ ) of the base of the copper wiring and the width (W ₁ ) of the top ₁₎ were measured. The results are shown in Tables 1-2.

As is clear from Tables 1 and ₂ , the difference (W ₂ −W ₁ ) between the width (W ₂ ) of the base of the copper wiring and the width (W ₁ ) of the top in Examples 1 to 9 is compared with Comparative Examples 1 to 3. It was small compared with that it was confirmed that there was little undercut. Thereby, the printed wiring board which has a fine and high-density wiring pattern can be manufactured with a sufficient yield.

  The present invention can be applied to the formation of various wirings such as wiring on a glass substrate, wiring on the surface of a plastic substrate, wiring on the surface of a semiconductor, in addition to forming wiring on a printed wiring board.

It is sectional drawing which shows the wiring part of the printed wiring board in one Embodiment of this invention.

Explanation of symbols

1 Substrate 2 Copper wiring 3 Resist resin W ₁ Width of top of copper wiring W ₂ Width of base of copper wiring

Claims (14)

A copper or copper alloy etchant,
An oxidizing metal ion source having a metal ion concentration of 14 to 155 g / liter,
7 to 180 g / liter of at least one acid selected from inorganic acids and organic acids;
An etching agent comprising an aqueous solution containing an azole having only a nitrogen atom as a different atom in the ring in a range of 0.1 to 50 g / liter.   The etching agent according to claim 1, wherein the oxidizing metal ion source is a cupric ion source.   The etching agent according to claim 1, wherein the oxidizing metal ion source is a ferric ion source.   The etching agent according to claim 1, wherein the acid is hydrochloric acid.   The etching agent of Claim 1 which contains the said azole in the range of 0.1-15 g / liter.   The etching agent according to any one of claims 1 to 5, wherein the etching agent further contains at least one selected from a cationic surfactant, glycol and glycol ether.   The etching agent of Claim 2 containing 30-330 g / liter of cupric chloride as said cupric ion source. A replenisher that is added to the etchant when the etchant according to any one of claims 1 to 7 is used repeatedly,
7 to 360 g / liter of at least one acid selected from inorganic acids and organic acids;
A replenisher comprising an aqueous solution containing an azole having only a nitrogen atom as a different atom in the ring in a range of 0.1 to 50 g / liter.   The replenisher according to claim 8, wherein the acid is hydrochloric acid. A method of manufacturing a wiring by etching copper or a copper alloy,
A portion of a copper layer on an electrical insulating material that is not covered with an etching resist is etched using the etching agent according to claim 1 to form a wiring. Production method.   When the etchant is repeatedly used, the replenisher according to claim 8 is added to the etchant to maintain copper or a copper alloy while maintaining a copper ion concentration in the etchant of 155 g / liter or less. The method for manufacturing a wiring according to claim 10, wherein etching is performed.   The method for manufacturing a wiring according to claim 10, wherein after etching copper or a copper alloy using the etchant, the etched portion is cleaned with a cleaning solution that dissolves components of the etchant.   The method of manufacturing a wiring according to claim 12, wherein the cleaning liquid is at least one solution selected from an acidic solution, a solution containing a substance that forms a complex compound with metal ions in the etching agent, and an organic solution.   The wiring manufacturing method according to claim 10, wherein when the etching agent is repeatedly used, copper or a copper alloy is etched while blowing a gas containing at least one of oxygen and ozone into the etching agent.

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