KR20150092116A - Etching fluid, replenishing fluid, and method for forming copper wiring - Google Patents

Abstract

The present invention provides an etching solution, a replenishing liquid, and a method of forming a copper wiring that can suppress side etching without deteriorating the linearity of the copper wiring. The etching solution of the present invention is a copper etching solution which is an aqueous solution containing an acid, an oxidizing metal ion and Compound A, and the compound A is a thiol group, a sulfide group and a disulfide group (provided that a sulfide group and a disulfide group are sulfur atoms and Containing hetero atom is a group which is connected by a single bond and does not form a pi conjugate), and an amino group in the molecule.

Description

TECHNICAL FIELD [0001] The present invention relates to an etching solution, a replenishing solution, and a method for forming a copper wiring,

The present invention relates to a copper etching solution and its replenishing solution, and a method for forming a copper wiring.

In the production of a printed wiring board, when a copper wiring pattern is formed by a photoetching method, an iron chloride based etching solution, a copper chloride based etching solution, an alkaline etching solution, or the like is used as an etching solution. When these etchants are used, copper under an etching resist called side etching sometimes dissolves from the side of the wiring pattern. That is, by covering with the etching resist, an undesired portion (that is, a copper wiring portion) is originally removed by etching with the etching solution, and the width becomes narrow from the bottom portion to the top portion of the copper wiring Lt; / RTI > In particular, when the copper wiring pattern is fine, such side etching must be reduced as much as possible. An etchant in which an azole compound is mixed to suppress the side etching has been proposed (for example, see Patent Documents 1 and 2 below).

However, in the etching solution described in Patent Document 1, the side etching suppressing effect is still insufficient.

According to the etching solution described in Patent Document 2, side etching can be suppressed. However, when the etching solution described in Patent Document 2 is used in a usual manner, there is a fear that side surfaces of the copper wiring may be shaken. If the side surface of the copper wiring is wobbled, the linearity of the copper wiring is deteriorated, and when the copper wiring width is optically inspected from the upper side of the printed wiring board, there is a fear that misrecognition is caused. Further, if the linearity at the extreme end deteriorates, the impedance characteristic of the printed wiring board may deteriorate.

As described above, in the conventional etching solution, it is difficult to suppress the side etching without damaging the linearity of the copper wiring.

Patent Document 1: JP-A-6-57453 Patent Document 2: JP-A-2005-330572

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and an object thereof is to provide an etching liquid, a replenishing liquid, and a copper wiring forming method which can suppress side etching without deteriorating the linearity of the copper wiring.

The etching solution of the present invention is an etching solution of copper, which is an aqueous solution containing an acid, an oxidizing metal ion and Compound A, and the compound A is a thiol group, a sulfide group and a disulfide group (provided that a sulfide group and a disulfide group are sulfur atoms and Is a group which is linked by a single bond and does not form a pi conjugate), and an amino group in the molecule.

The replenisher of the present invention is a replenisher to be added to the etching solution when the etching solution of the present invention is continuously or repeatedly used, and is an aqueous solution containing an acid and a compound A. When the compound A is a thiol group, a sulfide group and a disulfide group [provided that a sulfide group and a disulfide group are at least a group selected from the group consisting of a sulfur atom and a hetero atom connected thereto by a single bond and not forming a π conjugate] Containing functional group and an amino group in the molecule.

The copper wiring forming method of the present invention is characterized in that etching is performed using the etching solution of the present invention in the copper wiring forming method for etching a portion of the copper layer not covered with the etching resist.

In the present invention, "copper" may be composed of copper or copper alloy. In this specification, "copper" refers to copper or a copper alloy.

According to the present invention, it is possible to provide an etching liquid, a replenishing liquid, and a copper wiring forming method that can suppress the side etching without deteriorating the linearity of the copper wiring.

1 is a partial cross-sectional view showing an example of a copper wiring after etching by the etching solution of the present invention.

The etching solution of the present invention is an aqueous solution containing an acid, an oxidizing metal ion, and a compound A, wherein the compound A is a thiol group, a sulfide group and a disulfide group (provided that the sulfide group and the disulfide group have a sulfur atom and a hetero atom Containing group and at least one sulfur-containing functional group and amino group selected from the group consisting of a group which is linked by a bond and which does not form a pi conjugate).

1 is a partial cross-sectional view showing an example of a copper wiring after etching by the etching solution of the present invention. On the copper wiring 1, an etching resist 2 is formed. The protective coating 3 is formed on the side surface of the copper wiring 1 immediately below the end portion of the etching resist 2. It is considered that the protective coating 3 is mainly formed by the copper ions and the salt thereof and the compound A generated in the etching solution along with the progress of the etching. According to the etching solution of the present invention, it is considered that a uniform protective film (3) is formed because the compound A is contained. As a result, it is considered that the side etching can be suppressed without deteriorating the linearity of the copper wiring 1 because the shaking of the copper wiring 1 is reduced. Therefore, according to the etching solution of the present invention, it is possible to improve the yield in the production process of the printed wiring board. Further, the protective coating 3 can be easily removed by a treatment with a removing solution after the etching treatment. As the removing solution, a mixed solution of hydrogen peroxide and sulfuric acid, an acidic solution such as hydrochloric acid, or an organic solvent such as dipropylene glycol monomethyl ether is preferable.

In addition, when the copper wiring is formed of the etching solution of Patent Document 2, it is considered that the uniformity of the protective film is formed thicker than when the etching solution of the present invention is etched, and thus the linearity of the copper wiring is impaired.

In addition, in the case of using the etching solution of Patent Document 2, the etching rate is slowed, and the processing speed is lowered and the productivity is lowered. However, the etching solution of the present invention maintains the same etching rate as a general iron chloride etching solution or copper chloride etching solution The yield can be improved without lowering the productivity.

The acid used in the etching solution of the present invention can be appropriately selected from inorganic acids and organic acids. Examples of the inorganic acid include sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid. Examples of the organic acid include formic acid (formic acid), acetic acid (acetic acid), oxalic acid, maleic acid, benzoic acid (benzoic acid) and glycolic acid. Of these acids, hydrochloric acid is preferable from the viewpoints of the stability of the etching rate and the dissolution stability of copper.

The concentration of the acid is preferably 7 to 180 g / L, more preferably 10 to 110 g / L. When the concentration of the acid is 7 g / L or more, it is possible to rapidly etch copper because the etching rate is accelerated. When the concentration of the acid is 180 g / L or less, the dissolution stability of copper is maintained and the deterioration of the working environment can be suppressed.

The oxidizing metal ion used in the etching solution of the present invention may be a metal ion capable of oxidizing metal copper, and examples thereof include cupric ion and ferric ion. From the standpoint of suppressing the side etching and the stability of the etching rate, it is preferable to use the cupric ion as the oxidizing metal ion.

The oxidizing metal ions can be contained in the etching liquid by blending oxidizing metal ions. For example, when a secondary copper ion source is used as an oxidizing metal ion source, specific examples thereof include copper chloride, copper sulfate, copper bromide, copper salt of organic acid, copper hydroxide and the like. For example, when ferric ion is used as the chloride ion source, specific examples thereof include iron chloride, iron bromide, iron iodide, iron sulfate, iron nitrate, and iron salts of organic acids.

The concentration of the oxidizing metal ion is preferably 10 to 250 g / L, more preferably 10 to 200 g / L, still more preferably 15 to 160 g / L, and most preferably 30 to 160 g / g / L. When the concentration of oxidizing metal ions is 10 g / L or more, it is possible to rapidly etch copper because the etching rate is increased. When the concentration of the oxidizing metal ion is 250 g / L or less, the dissolution stability of copper is maintained.

Since the etching solution of the present invention can suppress the side etching while preventing the linearity of the copper wiring from being eliminated, it is possible to prevent the side etching from being caused by the compound having at least one sulfur-containing functional group and an amine group in the molecule selected from the group consisting of a thiol group, a sulfide group and a disulfide group A is blended. In the present invention, both the sulfide group and the disulfide group refer to a group in which a sulfur atom and a hetero atom connected thereto are connected by a single bond and do not form a pi conjugate.

The compound A is not particularly limited as a compound having at least one sulfur-containing functional group and an amine group in the molecule selected from the group consisting of a thiol group, a sulfide group and a disulfide group, but is preferably selected from an aliphatic compound. Since the aliphatic compound has a higher solubility in an aqueous solution than an aromatic compound, it is considered that it is possible to easily form a uniform protective film.

Specific examples of the compound A include compounds having a thiol group and an amino group such as 2-aminoethanethiol, 2- (dimethylamino) ethanethiol, 2- (diethylamino) ethanethiol and 2- (diisopropylamino) ethanethiol; Compounds having sulfide groups and amino groups such as 2,2'-thiobis (ethylamine), 2- (ethylthio) ethylamine and tetramethylthiurammonosulfide; And compounds having disulfide groups and amino groups such as cystamine and bis (2-dimethylaminoethyl) disulfide. The compound A may be used in combination of two or more. Among them, it is preferable to have a thiol group and an amino group from the viewpoint of improving the linearity of the copper wiring and effectively suppressing the side etching.

The concentration of the compound A is preferably 0.005 to 10 g / L, more preferably 0.01 to 5 g / L. Within this range, the linearity of the copper wiring can be improved and the side etching can be effectively suppressed.

An alicyclic (alicyclic) amine compound may be added to the etching solution of the present invention in order to improve the linearity of the copper wiring and effectively suppress the side etching. When the alicyclic amine compound is compounded in the etching solution of the present invention, the concentration of the alicyclic amine compound in the etching solution is preferably 0.01 to 10 g / L, more preferably 0.02 to 5 g / L from the above viewpoint.

As the alicyclic amine compound, it is preferable to use an alicyclic amine compound having a molecular weight of about 43 to 500 from the viewpoints of improving the linearity of the copper wiring and effectively suppressing the side etching. The alicyclic amine compound is preferably a pyrrolidine- It is more preferable to use at least one alicyclic amine compound selected from the group consisting of piperazine compounds.

Among them, it is preferable to use a piperazine-based compound such as piperazine in order to effectively suppress the side etching and further improve the linearity of the copper wiring. It is preferable to use the piperazine-based compound represented by the following formula More preferable.

[In the formula (1), R ¹ and R ² each independently represent hydrogen or a hydrocarbon derivative having 1 to 6 carbon atoms. Provided that at least one of R ¹ and R ² represents a hydrocarbon derivative having 1 to 6 carbon atoms.

The term "hydrocarbon derivative" as used herein means that some of carbon or hydrogen in the hydrocarbon group composed of carbon and hydrogen may be substituted with other atoms or substituents. Examples of the hydrocarbon derivative include methyl, ethyl, propyl, butyl, aminomethyl, aminoethyl, aminopropyl, dimethylaminomethyl, dimethylaminoethyl, dimethylaminopropyl, hydroxymethyl, An allyl group, an acetyl group, a phenyl group, a hydroxyethoxymethyl group, a hydroxyethoxyethyl group, and a hydroxyethoxypropyl group.

Specific examples of the piperazine compound represented by Formula 1 include N-methylpiperazine, N-ethylpiperazine, N, N-dimethylpiperazine, N-allylpiperazine, N-isobutylpiperazine, N- (2-aminoethyl) piperazine, N-phenylpiperazine, 1,4-bis (3-aminopropyl) piperazine, 1- And the like. Among them, from the viewpoints of suppressing the side etching and improving the linearity of the copper wiring, the piperazine-based compound having at least one of R ¹ and R ² in the formula (1) has an amino group is preferable. Examples of such piperazine compounds include 1,4-bis (3-aminopropyl) piperazine, 1- (2-dimethylaminoethyl) -4-methylpiperazine, N- can do.

Examples of pyrrolidine compounds include pyrrolidine, 1-2- (hydroxyethyl) pyrrolidine, 1- (2-aminoethyl) pyrrolidine, N-methylpyrrolidine, Aminopyrrolidine, N-benzyl-3-aminopyrrolidine, and the like.

Examples of the piperidine compound include piperidine, N-piperidine ethanol, N-methylpiperidine, N-ethylpiperidine, 4-aminopiperidine, 4-piperidinecarboxylic acid, Piperidine, and the like.

Other components may be added to the etching solution of the present invention to such an extent as not to interfere with the effects of the present invention. For example, a component stabilizer, antifoaming agent and the like may be added. When the other component is added, the concentration is about 0.001 to 5 g / L.

The above etching solution can be easily prepared by dissolving each component in water. As the water, ionic substances and water from which impurities are removed are preferable. For example, ion-exchanged water, pure water, ultrapure water and the like are preferable.

The etching solution may be formulated so that each component is at a predetermined concentration at the time of use, or may be prepared by preparing a concentrate and diluting it immediately before use. The method of using the etching solution is not particularly limited, but it is preferable to etch using a spray as described later in order to effectively suppress the side etching. The temperature of the etching solution during use is not particularly limited, but it is preferable to use the etching solution at 20 to 55 占 폚 in order to effectively suppress the side etching after the productivity is maintained high.

The replenishing liquid of the present invention is a replenishing liquid to be added to the etchant when the etchant of the present invention is used continuously or repeatedly, and is an aqueous solution containing the acid and the compound A. Each component in the replenisher is the same as the component that can be compounded in the above-described etching solution of the present invention. By adding the replenishing liquid, the respective component ratios of the etchant are properly maintained, so that the effect of the above-described etchant of the present invention can be stably maintained. Further, the replenishment solution of the present invention may further contain a secondary copper ion source such as cupric chloride in a range that does not exceed a concentration of 14 g / L at the secondary copper ion concentration. In addition, a component added to the etching solution may be added to the replenishing solution of the present invention in addition to the above components.

The concentration of each component in the replenishing liquid is appropriately set in accordance with the concentration of each component in the etching solution. However, from the viewpoint of stably maintaining the effect of the etching solution of the present invention described above, the concentration of the acid is 7 to 360 g / L, It is preferable that the concentration is 0.005 to 10 g / L. When the etching liquid contains the alicyclic amine compound, the replenishing liquid preferably contains the alicyclic amine compound in a concentration of 0.01 to 10 g / L.

The copper wiring forming method of the present invention is characterized in that the copper wiring is formed by etching the portion of the copper layer not covered with the etching resist by using the etching solution of the present invention. As a result, the side etching can be suppressed without impairing the linearity of the copper wiring as described above. When the etching solution of the present invention is used continuously or repeatedly in the copper wiring forming step employing the copper wiring forming method of the present invention, it is preferable to perform etching while adding the above-described replenishing solution of the present invention. Since the respective component ratios of the etchant are appropriately maintained, the effect of the above-described etchant of the present invention can be stably maintained.

In the copper wiring forming method of the present invention, it is preferable that the etching solution is sprayed to a portion of the copper layer not covered with the etching resist by spraying. Side etching can be effectively suppressed. When spraying, the nozzle is not particularly limited, but a fan-shaped nozzle, a filling nozzle, or the like can be used.

When spraying with a spray, the spray pressure is preferably 0.04 MPa or more, more preferably 0.08 MPa or more. If the spray pressure is 0.04 MPa or more, a protective coating can be formed on the side of the copper wiring with an appropriate thickness. As a result, the side etching can be effectively prevented. The spray pressure is preferably 0.30 MPa or less from the viewpoint of preventing breakage of the etching resist.

Example

Next, Examples of the present invention will be described together with Comparative Examples. The present invention is not limited to the following examples.

Each of the etching solutions having the compositions shown in Tables 1 and 2 was prepared, etching was performed under the conditions described below, and each item was evaluated by the following evaluation method. In each of the etching solutions of the compositions shown in Tables 1 and 2, the remainder is ion-exchanged water. The concentrations of hydrochloric acid shown in Tables 1 and 2 are concentrations as hydrogen chloride.

(Test substrate used)

A copper clad laminate (copper foil laminate) in which an electrolytic copper foil (electrolytic copper foil) having a thickness of 12 占 퐉 (electrolytic copper foil JX, manufactured by Ikki Seisakusho Co., Ltd., standard profile copper foil, trade name: JTC foil) Treated with a catalyst-containing treatment liquid (product of Okuno Pharmaceutical Co., Ltd., trade name: Adokapaparizu), and then electroless copper plating films were formed using an electroless copper plating solution (product name: Adokappa series manufactured by Okuno Pharmaceutical Co., Ltd.). Next, an electrolytic copper plating film having a thickness of 13 탆 was formed on the electroless copper plating film by using an electrolytic copper plating solution (Doppuchnina SF manufactured by Okuno Pharmaceutical Co., Ltd.). An etching resist pattern having a thickness of 25 占 퐉 was formed on the obtained electrolytic copper plating film by using a dry film resist (trade name: SUNFORT AQ-2559, manufactured by Asahi Kasei Imperial Co., Ltd.). At this time, the etching resist pattern was a pattern in which a resist pattern of line / space (L / S) = 45 μm / 35 μm and a resist pattern of line / space (L / S) = 40 μm /

(Etching condition)

The etching was carried out under the conditions of a spray pressure of 0.12 MPa and a treatment temperature of 40 DEG C using a filling nozzle (trade name: ISJIX020, manufactured by Ikeuchi Co., Ltd.). The etching processing time was set to a time point at which the width of the bottom of the copper wiring after etching in the resist pattern area of line / space (L / S) = 45 μm / 35 μm reached 40 μm. After the etching, the substrate was washed with water and dried, and the following evaluations were carried out.

(Side etching amount)

A part of each of the etched test substrates was cut, embedded in a cold-embedding resin, and polished so that the cross section of the copper wiring could be observed. The cross section was observed at a magnification of 200 times using an optical microscope and the width W1 of the copper wiring top portion and the width W1 of the copper wiring bottom portion in the resist pattern area of line / space (L / S) = 45 μm / The width W2 of the bottom portion was measured and the difference W2-W1 was taken as the side etching amount (占 퐉). The results are shown in Tables 1 and 2.

(Linearity)

Each of the etched test substrates was immersed in a 3 wt% aqueous solution of sodium hydroxide for 60 seconds to remove the etching resist. Thereafter, protective coating was removed with a sector nozzle (product name: VP9020, product of Ikeuchi) under the conditions of spray pressure of 0.12 MPa, treatment temperature of 30 DEG C and treatment time of 30 seconds by using hydrochloric acid (hydrogen chloride concentration: 7 wt% . Then, the upper surface of the test substrate was observed at a magnification of 200 times using an optical microscope, and the width of the copper wiring top portion in the resist pattern region of line / space (L / S) = 40 m / And the standard deviation thereof was determined as linearity (占 퐉). The results are shown in Tables 1 and 2.

Furtherance Amount of blending Processing
time
(second) side
Etching amount (占 퐉) Linearity
(탆)
Example 1
Ferric chloride 100 g / L
(34 g / L as ferric ion)
69.5

14.5

0.44
Hydrochloric acid 10 g / L 2-aminoethanethiol hydrochloride 1.0 g / L
Example 2
Cupric chloride · dihydrate 350 g / L
(130 g / L as cupric ion)
60.0

13.2

0.61
Hydrochloric acid 100 g / L 2-aminoethanethiol hydrochloride 0.5 g / L
Example 3 Cupric chloride · dihydrate 350 g / L
(130 g / L as cupric ion)
70.0

13.0

0.53
Hydrochloric acid 100 g / L 2- (dimethylamino) ethanethiol hydrochloride 0.05 g / L
Example 4
Cupric chloride · dihydrate 350 g / L
(130 g / L as cupric ion)
70.0

11.3

0.52
Hydrochloric acid 100 g / L 2- (Diethylamino) ethanethiol hydrochloride 0.05 g / L
Example 5
Cupric chloride · dihydrate 300 g / L
(112 g / L as cupric ion)
66.8

14.2

0.58
Hydrochloric acid 100 g / L 2,2'-thiobis (ethylamine) 0.05 g / L
Example 6

Cupric chloride · dihydrate 350 g / L
(130 g / L as cupric ion)
59.3


12.2


0.45

Hydrochloric acid 100 g / L 2-aminoethanethiol hydrochloride 0.05 g / L Piperidine 0.2 g / L
Example 7
Cupric chloride · dihydrate 350 g / L
(130 g / L as cupric ion)
65.0

13.9

0.50
Hydrochloric acid 100 g / L Cystamine hydrochloride 0.05 g / L
Example 8

Cupric chloride · dihydrate 350 g / L
(130 g / L as cupric ion)
58.0


10.2


0.19

Hydrochloric acid 100 g / L 2-aminoethanethiol hydrochloride 0.05 g / L N- (2-aminoethyl) piperazine 2.0 g / L
Example 9

Cupric chloride · dihydrate 350 g / L
(130 g / L as cupric ion)
59.7


12.1


0.46

Hydrochloric acid 100 g / L 2-aminoethanethiol hydrochloride 0.05 g / L 1- (2-hydroxyethyl) pyrrolidine 1.5 g / L
Example 10
Cupric chloride · dihydrate 300 g / L
(112 g / L as cupric ion)
69.0

14.0

0.63
Hydrochloric acid 70 g / L 2- (ethylthio) ethylamine 0.5 g / L
Example 11

Cupric chloride · dihydrate 350 g / L
(130 g / L as cupric ion)
58.9


11.5


0.25

Hydrochloric acid 100 g / L 2-aminoethanethiol hydrochloride 0.05 g / L Piperazine 0.5 g / L

Furtherance Amount of blending Processing
Time (seconds) side
Etching amount
(탆) Linearity (㎛) Comparative Example 1
Cupric chloride · dihydrate 350 g / L
(130 g / L as cupric ion) 65.0
16.2
0.24
Hydrochloric acid 100 g / L Comparative Example 2
Ferric chloride 100 g / L
(Ferric ion)
34 g / L) 69.2
17.4
0.64
Hydrochloric acid 10 g / L
Comparative Example 3

Cupric chloride · dihydrate 260 g / L
(97 g / L as cupric ion)
68.0


14.4


1.06

Hydrochloric acid 90 g / L 2-aminobenzothiazole 1.0 g / L Triethylene glycol 20.0 g / L
Comparative Example 4

Cupric chloride · dihydrate 300 g / L
(112 g / L as cupric ion)
136.5


3.7


2.31

Hydrochloric acid 20 g / L 5-Amino-1H-tetrazole 1.5 g / L 2-phenoxyethanol 1.0 g / L
Comparative Example 5
Cupric chloride · dihydrate 350 g / L
(130 g / L as cupric ion)
70.0

16.6

0.55
Hydrochloric acid 100 g / L Ethylenediamine dihydrochloride 0.1 g / L
6.
Cupric chloride · dihydrate 350 g / L
(130 g / L as cupric ion)
70.0

16.4

0.58
Hydrochloric acid 100 g / L 2- (ethylthio) ethanol 0.5 g / L

As shown in Table 1, according to the embodiment of the present invention, good results were obtained for all evaluation items. On the other hand, as shown in Table 2, in Comparative Examples, inferior results were obtained in some evaluation items as compared with the Examples. From these results, it was found that the present invention can suppress the side etching without impairing the linearity of the copper wiring.

Explanation of symbols

1: Copper wiring

2: etching resist

3: Protective coating

Claims (11)

In the copper etching solution,
Wherein the etching solution is an aqueous solution containing an acid, an oxidizing metal ion, and Compound A, and the compound A is a thiol group, a sulfide group, and a disulfide group (provided that a sulfide group and a disulfide group have a sulfur atom and a hetero atom Containing group and at least one sulfur-containing functional group selected from the group consisting of a group not forming a π conjugate and an amino group in the molecule. The method according to claim 1,
Wherein the acid is hydrochloric acid. 3. The method according to claim 1 or 2,
Wherein the oxidizing metal ion is a cupric ion. 4. The method according to any one of claims 1 to 3,
Wherein the compound A is an aliphatic compound. 5. The method according to any one of claims 1 to 4,
The concentration of the acid is 7 to 180 g / L,
The concentration of the oxidizing metal ion is 10 to 250 g / L,
Wherein the concentration of the compound A is 0.005 to 10 g / L. 6. The method according to any one of claims 1 to 5,
And an alicyclic amine compound. The method according to claim 6,
Wherein the alicyclic amine compound is at least one selected from the group consisting of a pyrrolidine-based compound, a piperidine-based compound, and a piperazine-based compound. 8. The method of claim 7,
Wherein the piperazine compound is a compound represented by the following formula (1).
[Chemical Formula 1]

[In the formula (1), R ¹ and R ² each independently represent hydrogen or a hydrocarbon derivative having 1 to 6 carbon atoms. Provided that at least one of R ¹ and R ² represents a hydrocarbon derivative having 1 to 6 carbon atoms. 9. The method according to any one of claims 6 to 8,
Wherein the concentration of the alicyclic amine compound is 0.01 to 10 g / L. A replenishment liquid to be added to the etchant when the etchant of any one of claims 1 to 9 is continuously or repeatedly used,
Wherein the replenishing liquid is an aqueous solution containing an acid and a compound A,
The compound A is selected from the group consisting of a thiol group, a sulfide group and a disulfide group (provided that a sulfide group and a disulfide group are groups in which a sulfur atom and a hetero atom connected thereto are connected by a single bond and do not form a π conjugate) Containing functional group and an amino group in the molecule. A copper wiring forming method for etching a portion of a copper layer not covered by an etching resist,
A method for forming a copper wiring, characterized in that etching is performed using the etching solution of any one of claims 1 to 9.

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