KR20100123652A - Etching solution for copper-containing multilayer film - Google Patents

Abstract

PURPOSE: An etching solution for copper containing stacked layer, which controls the dissolution of copper alloy oxide layer, is provided to perform the blanket etching of a copper alloy stacked layer in a tapered shape. CONSTITUTION: An etching solution for copper containing stacked layer comprises peroxide and organic acid. The copper-containing lamination film is Cu/CuXO or CuX / CuXO. X is Ca or MgAl. The pH of etchant is 3-6. The peroxide is hydrogen peroxide. Etchant additionally contains a chelating agent. The organic acid is citric acid or glycine. The peroxide comprises persulfate or persulfated salts. The organic acid is acetic acid.

Description

Etching solution for copper-containing multilayer film

TECHNICAL FIELD The present invention relates to an etching solution for a laminated film used for a semiconductor or the like.

As the display area of the LCD display device becomes larger, the gateway line and the data line connected to the thin film transistor become longer, and the resistance of the wiring increases, which causes problems such as signal delay. Although aluminum (Al) is used for the metal wiring of the conventional liquid crystal display device, copper (Cu) wiring with lower resistance is used for a large substrate.

In the case of copper (Cu) wiring, a metal film such as Ti, Mo, Cr, or the like is used for the barrier metaaru to prevent Cu from diffusing into the semiconductor film and to improve the adhesion between the semiconductor film and the semiconductor film. That is, a laminated film of Cu / Mo, Cu / Ti, Cu / Cr, or the like is formed. In the case of etching the laminated film structure, the etching process of the Cu film is performed, followed by the two-step method of etching the Mo and Ti to the base film and the Cu / Mo or Cu / Ti laminated film in one liquid, and the etching process is performed at once. There are two methods of batch processing. Although the latter batch processing method is advantageous as a work process, it is difficult to collectively etch the laminated film into a tapered shape without step difference in consideration of the effect of battery effect, since it is difficult to etch a metal laminated film having different corrosion resistance in one solution. In addition, the development of a batch etching solution is very difficult in that excessive etching in the transverse direction (side etching) must be avoided with the maximum force in the processing accuracy of the wiring.

Against this background, a batch of etching methods such as Cu / Mo, Cu / Ti, Cu / Cr, etc. have been studied by selecting an effective antioxidant for each metal constituting each layer.

For example, Patent Literature 1 discloses an etching technique using potassium peroxide as a Cu dissolving oxidant, and studies on etching liquids in which various acids are combined with a base laminated metal. That is, in the case of Cu / Ti, an etching composition combining fluoric acid or peroxide sulfate and fluoride, Cu / Mo, an etching composition combining phosphoric acid and nitric acid, and Cu / Cr Further discloses an etching composition combining hydrochloric acid.

In addition, Patent Literatures 2 to 4 disclose etching techniques using hydrogen peroxide as a Cu dissolving oxidant, and it is studied to simultaneously etch a Cu / Mo or Cu / Ti laminated film by using various organic acids, neutral salts, or even various additives in combination. It is becoming.

Recently, a laminated film including a copper alloy oxide layer has been developed as a laminated film instead of a Cu / Mo and Cu / Ti laminated film. These have the advantage that not only the performance is excellent as a base film but also each layer of the lamination can be formed in the same apparatus also in the film forming process. However, no effective etching method for the laminated film including this newly developed copper alloy oxide layer is considered.

[Patent Document 1] Patent No. 3974305

[Patent Document 2] Japanese Patent Application Laid-Open No. 2002-302780

[Patent Document 3] US Patent Application Publication No. 2006/105579

[Patent Document 4] Japanese Patent Application Laid-Open No. 2004-193620

The present inventors attempt to develop a batch etching technique of a new laminated film composed of copper and a copper alloy oxide, such as CuMg / CuMgO, CuCa / CuCaO, Cu / CuCaO, Cu / CuAlMgO, and the like, for example. , FeCl ₃ , CuCl ₂ and mixed acid etchant, which have been used for etching Cu single layer films and batch etching of conventional copper laminated films such as Cu / Mo, Cu / Ti, Cu / Cr, are used for lower layer films such as CuMgO and CuCaO. Since the solubility is high, there exists a problem that a base film side etching becomes large and a taper shape cannot be obtained.

That is, the problem of the present invention solves the above problems, and in order to collectively etch the Cu metal layer and the Cu alloy oxide layer, it is possible to control the dissolution of the highly soluble copper alloy oxide layer, and furthermore, in the lamination which is a batch etching object, It is to provide an etching solution and an etching method in which the dissolution of all the layers including the Cu alloy oxide layer reproduces a condition having a proper balance.

As a result of intensive studies to solve such problems, the inventors have surprisingly found a method for batch-etching the laminated film well using an etching solution containing a peroxide and an organic acid. Came to complete.

That is, the present invention relates to an etching solution containing a peroxide and an organic acid in an etching solution for etching a copper-containing laminated film on a substrate, comprising a copper oxide layer or a copper alloy oxide layer in contact with the substrate.

Moreover, this invention relates to the said etching liquid whose copper containing laminated film is Cu / CuXO or CuX / CuXO (wherein X is Ca or MgAl).

Furthermore, this invention relates to the said etching liquid whose pH is 3-6.

Moreover, this invention relates to the said etching liquid whose peroxide is hydrogen peroxide.

Furthermore, this invention relates to the said etching liquid which further contains a chelating agent.

The present invention also relates to the above etching solution wherein the chelating agent is EDTA and its alkali salt or diethylenetriamine pentacetic acid and its alkali salt.

Furthermore, this invention relates to the said etching liquid whose organic acid is citric acid or glycine.

Moreover, this invention relates to the said etching liquid in which a peroxide contains a persulfate or a persulfate.

Furthermore, the present invention relates to the etching solution selected from the group consisting of persulfate KHSO ₅ , NaHSO ₅ , K ₂ S ₂ O ₈ , Na ₂ S ₂ O ₈ and (NH ₄ ) ₂ S ₂ O ₈ .

Moreover, this invention relates to the said etching liquid whose organic acid is acetic acid.

Furthermore, the present invention relates to a method for etching a copper-containing laminated film of a board comprising a copper oxide layer or a copper alloy oxide layer in contact with a substrate, the method comprising the step of etching using an etchant comprising a peroxide and an organic acid. will be.

In the above configuration, the layer in contact with the substrate of the copper-containing laminated film can act on the copper oxide layer or the copper alloy oxide layer to control the dissolution rate of the copper alloy oxide layer, for example, Cu / CuXO ( X can achieve batch etching of any metal) laminated | multilayer film to taper shape with little side etching.

This is because the batch etching solution for the conventional copper laminated film is all caused by metal oxide dissolution, and the dissolution of the copper alloy oxide laminated film does not involve a change in the oxidation number of copper, that is, it is considered to be chemical dissolution instead of oxidation dissolution. When the oxide film is regarded as an oxide such as CuO, CuO _2, etc., the boundary between CuO, CuO ₂ stable region and Cu ion stable region because Cu ion becomes Cu ions instead of the stable region of the oxide at pH 4 or lower in the Cu potential-pH line state diagram. It can also be explained that since the dissolution rate of a Cu alloy oxide film can be controlled by controlling to an example of conditions: pH 3-6).

1 is No. CuMg / CuMgO substrate treatment result with 3 solution It is the figure which observed the cross section after 110 sec (JET * 1.5) etching process (Example 3).
2 is No. Cu / Mo Substrate Treatment with Three Solutions As a result, the cross section after 171 sec (JET × 1.5) etching treatment was observed (Comparative Example 3).
3 is No. CuMg / CuMgO substrate treatment result with 8 solution The figure which observed the cross section after 96 sec (JET * 1.5) etching process (Example 8).
4 is No. CuMg / CuMgO substrate treatment result with 9 solution The figure which observed the cross section after 132 sec (JET * 1.5) etching process (Example 9).
5 is No. Cu / Mo substrate processing result by 8 solution The figure which observed the cross section after 158 sec (JET * 1.2) etching process (comparative example 8).
6 is No. Cu / CuCaO substrate treatment result with 10 solutions The figure which observed the cross section after 53 sec (JETx1.5) etching process (Example 10).
7 is No. Cu / Mo substrate processing result by the 10 solution It is the figure which observed the cross section after 354 sec (JET * 1.5) etching process (comparative example 10).

This invention provides the said etching liquid containing a peroxide and an organic acid in the etching liquid for etching the copper containing laminated film on the board | substrate containing the copper oxide layer or copper alloy oxide layer which contact | connects a board | substrate in one Embodiment.

The substrate is preferably any one that can be used for a semiconductor substrate and the like, and generally includes glass, quartz, ceramics and the like.

In the present invention, the copper-containing laminated film includes a layer of copper or a copper alloy (alloy of copper and all metals) and a layer of copper oxide or copper alloy oxide. Generally, lamination | stacking can carry out batch etching also in two or three layers or more. In addition, metal elements other than copper of the copper alloy layer may be the same as or different from metal elements other than copper of the copper alloy oxide layer. Preferred copper-containing laminated films in the present invention are Cu / CuXO or CuX / CuXO, wherein X is Mg, Ca or MgAl.

Although the pH of an etching liquid is not limited in this invention, It is preferable that it is 3-6 from a viewpoint of the kind and thickness of a laminated film, a taper shape, side etching amount, etc., and it is especially preferable that it is 3.5-5.5. pH adjustment uses a buffer of organic acids or organic acid salts, and may add a pH adjuster. If the pH is low, it is difficult to obtain a good taper shape because the lower copper oxide film is quickly dissolved. If the pH is high, the etching reaction of the Cu film does not proceed or the etching does not proceed at a practical etching rate.

Although the oxidizing agent (hydrogen peroxide) used for the etching liquid of this invention is not specifically limited, Hydrogen peroxide, a persulfate, a persulfate, a peracetic acid, a peracetic acid salt, a percarbonate, a percarbonate, etc. are mentioned. In particular, hydrogen peroxide, persulfate, and persulfate are preferable from the viewpoint of stability, easy access, easy handling, cost, and the like of hydrogen peroxide. Further, persulfates include, for example, KHSO ₅ , NaHSO ₅ , K ₂ S ₂ O ₈ , Na ₂ S ₂ O ₈ (NH ₄ ) ₂ S ₂ O ₈ And the like. Furthermore, hydrogen peroxide can be used in combination of 2 or more types as appropriate.

In the present invention, the concentration of hydrogen peroxide is not particularly limited, but in the case of using hydrogen peroxide, it is preferably 0.01 to 3.0 mol / L, more preferably 0.05 to 2.0 mol / L, and even more preferably 0.1 to 1.0 mol /. L. When the concentration of hydrogen peroxide is low, the etching rate is low, and when the concentration is high, the etching rate is high.

In the case of using persulfate or persulfate, the concentration of persulfate is preferably 0.01 to 3.0 mol / L, more preferably 0.05 to 2.0 mol / L, even more preferably 0.1 to 1.0 mol / L. . If the concentration of persulfate is low, the etching rate is slow, and if it is high, the etching rate is high.

Although the organic acid used for the etching liquid of this invention is not specifically limited, Citric acid, glycine, acetic acid, tartaric acid, succinic acid, lactic acid, a phthalate etc. are mentioned. In particular, citric acid, glycine and acetic acid are preferable in view of pH buffering function, solubility, accessibility, cost and the like. In addition, an organic acid can be used in combination of 2 or more type as appropriate.

In the present invention, the concentration of the organic acid is not particularly limited, but is preferably 0.05 to 5.0 mol / L, more preferably 0.05 to 3.0 mol / L, particularly preferably 0.1 to 2.0 mol / L, even more preferably 0.1 ˜1.0 mol / L. If the organic acid concentration is low, the action as a pH buffer is insufficient, making it difficult to maintain the etching solution within a predetermined pH range. In addition, when the concentration of the organic acid is high, there is a problem of solubility, and there is a problem in that the effect of high concentration cannot be sufficiently obtained.

Although the chelating agent used for the etching liquid of this invention is not specifically limited, EDTA and its alkali salt, diethylene triamine pentacetic acid and its alkali salt, nitrilo triacetic acid, its alkali salt, etc. are mentioned. In particular, EDTA and alkali salts thereof, diethylenetriamine pentacetic acid and alkali salts thereof are preferable from the viewpoint of chelating ability, solubility of the chelating agent, and the like. In addition, a chelating agent can be used in combination of 2 or more types as appropriate. By blending such a chelating agent and chelating metal ions such as Cu, Ca, and Mg dissolved by etching, there is an effect of suppressing precipitation in the solution of the etching reactant, for example, hydrogen peroxide decomposition reaction by Cu ions. It can be suppressed.

The concentration of the chelating agent in the present invention is not particularly limited, but is preferably 0.01 to 0.2 mol / L, more preferably 0.03 to 0.15 mol / L, still more preferably 0.05 to 0.1 mol / L. When the concentration of the chelate is low, the action is insufficient as a chelating agent, and when the concentration of the chelate is high, there is a problem that a uniform solution is not formed due to lack of solubility.

When using hydrogen peroxide as peroxide in this invention, it is preferable to use citric acid or glycine as an organic acid. Moreover, in this case, it is preferable to include EDTA disodium and diethylene triamine triacetate as additional chelating agent. As described above, in the case of containing hydrogen peroxide, organic acid and chelating agent, the respective concentrations are not particularly limited. For example, the organic acid is 0.05 to 3.0 mol / L, preferably 0.1 to 0.01 to 3.0 mol / L of hydrogen peroxide. To 2.0 mol / L, more preferably 0.1 to 1.0 mol / L, and the chelating agent is 0.01 to 0.2 mol / L, preferably 0.03 to 0.15 mol / L, more preferably 0.05 to 0.1 mol / L. Can be.

When persulfate or persulfate is used as peroxide in this invention, it is preferable to use acetic acid as an organic acid. In this case, although each concentration is not specifically limited, For example, per acetic acid and persulfate 0.01-3.0 mol / L, acetic acid is 0.05-5.0 mol / L, Preferably it is 0.1-3.0 mol / L, Preferably it may be 0.1-1.0 mol / L. If the acetic acid concentration is low, the action as a pH buffer is insufficient, and it is difficult to maintain the etching solution within a predetermined pH range. If the acetic acid concentration is high, there is a problem of acetic acid smell and a problem that the effect of high concentration cannot be sufficiently obtained.

The etching method of this invention WHEREIN: In the method of etching the copper containing laminated film on a board | substrate containing the copper oxide layer or copper alloy oxide layer which contact | connects a board | substrate, the process of etching using the etching liquid containing a peroxide and an organic acid. It includes.

Therefore, the layer in which the object to be etched is in contact with the substrate of the copper-containing laminated film is a copper oxide layer or a copper alloy oxide layer, and is not particularly limited except for using an etching solution containing an etching solution peroxide and an organic acid. Processes for etching can be used.

[Example]

1. CuMg / CuMgO / Glass Substrate Treatment (Examples 1-6)

A 500 Mm CuMgO film was sputtered on the glass substrate, and a 3000 Mm CuMg film was sputtered thereon to form a CuMg / CuMgO double laminated film. Further, the CuMg / CuMgO double laminated film was subjected to photoresist coating, and then selectively exposed and developed to form an etching mask. The etching liquids (No. 1-6) of Table 1 were prepared, and the said board | substrate was stirred and immersed at the solution temperature of 30 degreeC. It was visually observed to confirm the just etching time (JET), and JET 1.5 times was made into the processing time.

Solution No. CuMg / CuMgO / glass substrates were treated using 1-6 and the results are shown in Table 2.

As for Examples 1-6, the cross section was a taper shape in all, and the side etching amount was also comparatively small suppressed to 1.0-1.6 micrometers. In addition, no etching residues remained on the glass substrate.

In addition, a typical cross-sectional view (photograph by scanning electron microscope (SEM). Magnification: 40,000 times) is shown in Fig. 1 (CuMg / CuMgO substrate treatment result by No. 3 solution, after 110 sec (JET x 1.5) etching treatment (execution). Example 3)).

2. Cu / Mo / Glass Substrate Treatment (Comparative Examples 2 ~ 6)

A 250 mmW Mo film was sputtered onto the glass substrate, and a 4000 mmW Cu film was sputtered thereon to form a Cu / Mo double laminated film. Further, the Cu / Mo double laminated film was selectively exposed and developed after photoresist coating to form an etching mask. Etching liquids (No. 2 to 6) of Table 1 were prepared in the same manner as in Examples, and the substrate was stirred at a solution temperature of 30 ° C. and submerged. It was visually observed to confirm the just etching time (JET), and JET 1.5 times was made into the processing time.

Solution No. The Cu / Mo / glass substrates were treated using 2-6 and the results are shown in Table 3.

In addition, the solution No. corresponding to Comparative Example 1 was obtained. The experiment using 1 is the solution No. PH of 1 is 3.3, and solution No. Since it was clear that the shape would be defective from the result of 2-6, it was not performed.

In the Cu / Mo double layered film, the dissolution of the base Mo film proceeded rapidly in any treatment liquid, and the cross-sectional shape became a letter of " <&quot;, so that it was difficult to form a normal wiring. In the instinct form, the etching liquid composition is adjusted to a CuX / CuXO double laminated film, and the point is that the copper alloy oxide film dissolves at an appropriate rate. Therefore, it cannot simply be applied to existing Cu / Mo double layered films.

In addition, a typical cross-sectional view (photograph by scanning electron microscope (SEM). Magnification: 40,000 times) is shown in FIG. 2 (Cu / Mo substrate treatment with No. 3 solution, after 171 sec (JET × 1.5) etching treatment (Comparative Example). 3)).

3. CuMg / CuMgO / Glass Substrate Treatment (Examples 7-9)

Examples 1-6 The CuMg / CuMgO double laminated | multilayer film of the same shape as the board | substrate used was provided, and the etching operation by the solution (No. 7-9) shown in following Table 4 was performed. The solution was stirred at 30 ° C., immersed, and then visually observed to confirm the just etching time (JET), and JET 1.5 times was used as the treatment time.

Solution No. The CuMg / CuMgO / glass substrates were treated using 7-9 and the results are shown in Table 5.

In Examples 7 to 9, the cross section was tapered, and the amount of side etching was also suppressed to be relatively small at 0.9 to 1.3 µm. In addition, no etching residues remained on the glass substrate.

In addition, typical cross-sectional observation is also a photograph by a scanning electron microscope (SEM). Magnification: 40,000 times) in FIG. 3 (CuMg / CuMgO substrate treatment with No. 8 solution, 96 sec (JET × 1.5) after etching treatment (Example 8)) and FIG. 4 (CuMg / CuMgO with solution No. 9) Substrate treatment results are shown after (132 sec (JET x 1.5) etching treatment (Example 9)).

4. Cu / Mo / Glass Substrate Processing (Comparative Examples 7 ~ 9)

As a comparative example, using the Cu / Mo double laminated film similar to the said Comparative Examples 2-6, it stirred and immersed at the solution temperature of 30 degreeC with the etching liquid (No. 7-9) shown in Table 4 similarly to an Example. It was visually observed to confirm just etching time (JET), and JET 1.2 times was made into the processing time.

Solution No. The Cu / Mo / glass substrates were treated using 7-9 and the results are shown in Table 6.

In the Cu / Mo double layered film, the dissolution of the base Mo film proceeds rapidly in any treatment liquid, the cross-sectional shape becomes a little ">" in the vertical form, and the side etching amount is 3.0 µm, so that normal wiring is formed. It was difficult. In the instinct form, the etching liquid composition is adjusted to a CuX / CuXO double laminated film, and the point is that the copper alloy oxide film dissolves at an appropriate rate. It is not applicable to existing Cu / Mo double layered films.

In addition, a typical cross-sectional view (photograph by scanning electron microscope (SEM). Magnification: 40,000 times) is shown in Fig. 5 (Cu / Mo substrate treatment result by No. 8 solution, after 158 sec (JET × 1.2) etching treatment (compared to Example 8)).

5. Various Cu Lamination Film Treatment (Examples 10 to 12 and Comparative Example 10)

A Cu / CuCaO double layered film and a CuCa / CuCaO double layered film were fabricated by sputtering a 500 mm3 CuCaO film on a glass substrate and sputtering a 3000 mm3 Cu or CuCa film thereon. Further, after sputtering a 500 mW CuMgAlO film on the glass substrate as an initial layer, a Cu film of 3000 mW was sputtered thereon to produce a Cu / CuMgAlO double stack. After the photoresist coating on this double layered film, it was selectively exposed and developed to form an etching mask. Next, the etching liquid (No. 10) shown in Table 7 was prepared, and it stirred and submerged at the solution temperature of 30 degreeC with respect to each said double layer board | substrate. Visual observation was conducted to confirm the just etching time (JET), and JET 1.5 times was taken as the treatment time.

In Comparative Example 10, the Cu / Mo double laminated film was used in the same manner as in Comparative Examples 2 to 6, and was stirred and immersed at the solution temperature of 30 ° C. with the etching solution (No. 10) shown in Table 7 as in the Example. . Visual observation was conducted to confirm the just etching time (JET), and JET 1.5 times was taken as the treatment time.

Solution No. Various Cu laminated films by 10 were treated and the results are shown in Table 8.

The double laminated film of Cu / CuCaO, CuCa / CuCaO, Cu / CuMgAlO also had a pure tapered shape in cross section, and the side etching amount was suppressed relatively small at 0.6 to 1.3 μm. In addition, no etching residues remained on the glass substrate.

Cross-sectional observation (photograph by scanning electron microscope (SEM). Magnification: 40,000 times) is shown in Fig. 6 (Cu / CuCaO substrate treatment result by No. 10 solution, 53 sec (JET x 1.5) after etching treatment (Example 10) ).

On the other hand, in the Cu / Mo double laminated film, dissolution of the basic Mo film proceeds quickly, the cross-sectional shape becomes "inverse taper shape", and the side etching amount is also large at 3.0 µm, and fine particles remain on the glass substrate. It was difficult to form normal wiring. In the instinct form, the etching liquid composition is adjusted to a CuX / CuXO double laminated film, and the point is that the copper alloy oxide film dissolves at an appropriate rate. It is not applicable to existing Cu / Mo double layered films.

Cross-sectional observation (photograph by scanning electron microscope (SEM). Magnification: 40,000 times) is shown in Fig. 7 (Cass / No substrate treatment result No.10 solution 354sec (JET × 1.5) after etching treatment (Comparative Example 10)) Shown in

6. Various Cu laminated film work (Examples 13-15 and Comparative Example 11)

The etching solution (No. 7) shown in Table 4 was prepared for each of the Cu / CuCaO, CuCa / CuCaO, and Cu / CuMgAlO double stacked films using Examples 10 to 12, stirred at a solution temperature of 30 ° C, and immersion. Visual observation was conducted to confirm the just etching time (JET), and JET 1.5 times was taken as the treatment time.

In the same manner as in Comparative Examples 2 to 6 described above in Comparative Example 11, using an Cu / Mo double laminated film, the solution was stirred and immersed at the solution temperature of 30 ° C. with the etching solution (No. 7) shown in Table 4 in the same manner as in Example. Visual observation was conducted to confirm the just etching time (JET), and JET 1.5 times was taken as the treatment time.

Liquid No. Various Cu laminated films by 7 were treated and the results are shown in Table 9.

The double laminated film of Cu / CuCaO, CuCa / CuCaO, Cu / CuMgAlO also had a pure tapered shape in cross section, and the side etching amount was suppressed to be relatively small at 0.5 to 1.0 µm. In addition, no etching residues remained on the glass substrate.

On the other hand, in the Cu / Mo double layered film, the cross-sectional shape of the base Mo film proceeded quickly so that the cross-sectional shape was vertical and the side etching amount was 8.3 m, and it was difficult to form a normal wiring.

In the instinct form, the etching liquid composition is adjusted to a CuX / CuXO double laminated film, and the point is that the copper alloy oxide film dissolves at an appropriate rate. It is not applicable to existing Cu / Mo double layered films.

According to the etching solution and the etching method of the present invention, the layer in contact with the substrate of the copper-containing laminated film is a copper oxide layer or a copper alloy oxide layer, and it is possible to achieve batch etching with little side etching in a tapered shape in a laminate substrate such as a new semiconductor.

Claims (11)

An etching solution for etching a copper-containing laminated film on a substrate, comprising a copper oxide layer or a copper alloy oxide layer in contact with the substrate, the etching solution comprising a peroxide and an organic acid.
The etching liquid according to claim 1, wherein the copper-containing laminated film is a Cu / CuXO or CuX / CuXO (wherein X is Ca or MgAl).
The etching liquid of Claim 1 or 2 whose said pH is 3-6.
The etching solution according to claim 1, wherein the peroxide is hydrogen peroxide.
The etching liquid of Claim 4 in which the said etching liquid contains a chelating agent further.
The etching solution according to claim 5, wherein the chelating agent is EDTA and alkali salts thereof or diethylenetriamine pentacetic acid and alkali salts thereof.
The etching solution according to claim 4, wherein the organic acid is citric acid or glycine.
The etching solution according to claim 1, wherein the peroxide contains persulfate or persulfate.
According to claim 8, wherein the persulfate is KHSO ₅ , NaHSO ₅ , K ₂ S ₂ O ₈ , Na ₂ S ₂ O ₈ And (NH ₄ ) ₂ S ₂ O ₈ .
The etching liquid of Claim 8 whose said organic acid is acetic acid.
A method of etching a copper-containing laminated film on a substrate comprising a copper oxide layer or a copper alloy oxide layer in contact with the substrate, the method comprising etching using an etchant comprising a peroxide and an organic acid.

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