KR20130008331A - An etching solution composition for copper layer/titanium layer - Google Patents

Abstract

PURPOSE: An etchant composition of a copper film and a titanium film is provided to uniformly etch a multi-metal film composed of the copper film and the titanium film at a rapid etching speed, thereby obtaining excellent etching properties. CONSTITUTION: An etchant composition of a copper film and a titanium film comprises 5-20wt% of persulfate, 0.01-2wt% of a fluorocompound, 0.001-3wt% of a chloridecompound, a mineral acid, salts thereof or 1-10wt% of a compound thereof, 0.3-5wt% of a ring-type aminocompound, an organic acid, salts thereof or 1-10wt% of a compound thereof, 0.1-5wt% of a P-toluenesulfonic acid, and remained water.

Description

Etch liquid composition of copper film / titanium film {AN ETCHING SOLUTION COMPOSITION FOR COPPER LAYER / TITANIUM LAYER}

The present invention relates to an etching liquid composition of a copper film / titanium film capable of ensuring excellent etching characteristics by uniformly batch-etching a multi-metal film composed of a copper film and a titanium film at a high etching rate.

Typical electronic circuits for driving semiconductor devices and flat panel displays are thin film transistors (TFTs). The manufacturing process of TFT-LCD typically forms a metal film as a wiring material for gate and source / drain electrodes on a substrate, forms a photoresist in an optional region of the metal film, and then etches the upper metal film using the photoresist as a mask. It consists of a process.

Conventionally, as a wiring material for gate and source / drain electrodes, a metal film in which aluminum or an alloy thereof and another metal are laminated is used. While aluminum is inexpensive and low in resistance, it does not have good chemical resistance and causes short phenomena with other conductive layers due to defects such as hillocks in later processes, or insulating layers due to contact with oxide layers. It causes the malfunction of the liquid crystal panel.

In view of this, a double metal film of a copper film and a titanium film has been proposed as a wiring material for the gate and source / drain electrodes.

However, in order to etch the double metal film of the copper film and the titanium film, there is a disadvantage in that two different etching solutions for etching each metal film must be used. In particular, a hydrogen peroxide-based or oxone-based etchant is mainly used to etch a copper film containing copper, and hydrogen peroxide-based etchant causes disproportionation reactions, resulting in instability due to decomposition of the composition itself or rapid change in composition over time. Hand-based etchant has a slow etching speed and unstable over time. In addition, an etching solution obtained by simply mixing an etching solution for a copper film and an etching solution for a titanium film was also used, but in this case, the etching profile was poor and difficulty in post-processing. In particular, the fluorine ion (F ⁻ ) used for etching titanium is a glass substrate and a silicon. It damages the layers and is not suitable for practical application.

The present invention has excellent storage stability without degrading the composition itself or a sudden change in composition with time, and can uniformly batch-etch multiple metal films composed of a copper film and a titanium film at a high etching rate to secure excellent etching characteristics. It is an object to provide an etching liquid composition of a copper film / titanium film.

Another object of the present invention is to provide a method of manufacturing a thin film transistor using the etching solution composition of the copper film / titanium film.

1. 5-20 wt% persulfate; 0.01 to 2% by weight of a fluorine compound; 0.001 to 3 weight percent of a chlorine compound; 1 to 10% by weight of inorganic acid, salts thereof or mixtures thereof; 0.3 to 5% by weight of the cyclic amine compound; 1 to 10% by weight of organic acid, salt thereof or mixture thereof; 0.1 to 5% by weight of p-toluenesulfonic acid; And a residual amount of water.

2. The etching solution of claim 1, wherein the persulfate is at least one selected from the group consisting of ammonium persulfate, sodium persulfate and potassium persulfate.

3. In the above 1, the fluorine compound is hydrofluoric acid, ammonium fluoride, ammonium bifluoride, ammonium fluoride, potassium fluoride, potassium bifluoride, potassium fluoride, sodium fluoride, sodium bifluoride, aluminum fluoride, boric fluoride, lithium fluoride And at least one copper film / titanium film selected from the group consisting of calcium fluoride.

4. In the above 1, wherein the chlorine compound is at least one selected from the group consisting of hydrochloric acid, sodium chloride, potassium chloride and ammonium chloride etching liquid composition of the copper film / titanium film.

5. The etching solution of claim 1, wherein the inorganic acid is at least one member selected from the group consisting of nitric acid, sulfuric acid, phosphoric acid, or perchloric acid.

6. In the above 1, the cyclic amine compound is 5-aminotetrazole, tolytriazole, benzotriazole, methylbenzotriazole, imidazole compound, indole compound, purine compound, pyrazole compound, pyridine An etching liquid composition of a copper film / titanium film of at least one selected from the group consisting of a compound, a pyrimidine compound, a pyrrole compound, a pyrrolidine compound and a pyrroline compound.

7. In the above 1, the organic acid is acetic acid, imino diacetic acid, ethylenediamine tetraacetic acid, butanoic acid, citric acid, iso citric acid, formic acid, gluconic acid, glycolic acid, malonic acid, oxalic acid, pentanic acid, sulfobenzoic acid, succinic acid, An etching solution composition of a copper film / titanium film of at least one member selected from the group consisting of sulfosuccinic acid, salicylic acid, sulfosalicylic acid, benzoic acid, lactic acid, glyceric acid, malic acid, tartaric acid, and propenoic acid.

8. according to the above 1, wherein the salt of the organic acid is a potassium salt, sodium salt or ammonium salt etching liquid composition of the copper film / titanium film.

9. The copper film according to the above 1, the copper film is a copper film or a copper alloy film containing at least one selected from the group consisting of copper and aluminum, magnesium, manganese, beryllium, hafnium, niobium, tungsten and vanadium. Etch solution composition of the membrane.

10. In the above 1, the titanium film is a titanium film is an etching solution composition of the copper film / titanium film.

11. In the above 1, the copper film / titanium film is an etching liquid composition of the copper film / titanium film is a multilayer film in which the copper film and titanium film are alternately stacked one or more times.

12. Method of manufacturing a thin film transistor comprising the step of forming a pattern of metal wiring by etching the copper film / titanium film with the etching liquid composition of any one of 1 to 11.

The etchant composition of the present invention can uniformly etch multiple metal films composed of a copper film and a titanium film at a high etching rate, thereby simplifying an etching process and improving productivity, and also securing excellent etching characteristics.

In addition, the etchant composition of the present invention is excellent in storage stability without causing a disproportionation reaction so that the composition itself is degraded or there is no sudden composition change with time.

In addition, the etchant composition of the present invention does not require expensive equipment during etching and does not damage equipment as well, which is advantageous in terms of large area and thus has an economical advantage.

The present invention relates to an etching liquid composition of a copper film / titanium film that can secure excellent etching characteristics.

Hereinafter, the present invention will be described in detail.

In the present invention, 'copper film / titanium film' means a multi-metal film in which a copper film and a titanium film are stacked. Specifically, a double metal film laminated in the order of the copper film / titanium film, and the double metal film stacked in the order of the titanium film / copper film. Further, a multi-metal film in which a copper film and a titanium film are alternately stacked in three or more layers, such as a triple metal film of a copper film / titanium film / copper film, a triple metal film of a titanium film / copper film / titanium film, and a copper film / titanium film / And multiple metal films of copper film / titanium film / copper film. At this time, the thickness of a copper film and a titanium film is not specifically limited.

Further, in the present invention, the 'copper film' may be a copper monolayer composed of only copper, and together with copper, aluminum (Al), magnesium (Mg), manganese (Mn), beryllium (Be), hafnium (Hf), and niobium ( It may be a copper alloy film composed of a copper alloy containing at least one selected from the group consisting of Nb), tungsten (W) and vanadium (V).

In addition, in the present invention, the 'titanium film' may be a titanium single film composed of titanium alone.

The etching liquid composition of the copper film / titanium film of this invention is a persulfate; Fluorine compounds; Chlorine compounds; Inorganic acids, salts thereof or mixtures thereof; Cyclic amine compounds; Organic acids, salts thereof or mixtures thereof; p-toluenesulfonic acid; And water in an optimal content ratio.

More specifically, 5 to 20% by weight persulfate; 0.01 to 2% by weight of a fluorine compound; 0.001 to 3 weight percent of a chlorine compound; 1 to 10% by weight of inorganic acid, salts thereof or mixtures thereof; 0.3 to 5% by weight of the cyclic amine compound; 1 to 10% by weight of organic acid, salt thereof or mixture thereof; 0.1 to 5% by weight of p-toluenesulfonic acid; And residual water.

Persulfate is the main component for etching copper film. Specific examples thereof include ammonium persulfate ((NH ₄ ) ₂ S ₂ O ₈ ), sodium persulfate (Na ₂ S ₂ O ₈ ), potassium persulfate (K ₂ S ₂ O ₈ ), and the like. It can mix and use species.

Persulfate may be included in 5 to 20% by weight of the total 100% by weight of the etchant composition, preferably 7 to 18% by weight. In this content range, the copper film is etched in an appropriate amount and an excellent etching profile can be obtained. If the content is less than 5% by weight, the copper film may not be etched or the etching rate may be slow. If the content is more than 20% by weight, the etching rate may be difficult to control the process.

The fluorine compound is a compound capable of dissociating into fluorine ions or polyatomic fluorine ions in the etching liquid composition, and is a main component for etching the titanium film and removes residues that may occur during etching. The type of the fluorine compound is not particularly limited, and specific examples thereof include hydrofluoric acid (HF), ammonium fluoride (NH ₄ F), ammonium bifluoride (NH ₄ HF ₂ ), ammonium fluoride (NH ₄ BF ₄ ), and fluoride Potassium (KF), Potassium Bifluoride (KHF ₂ ), Potassium Borofluoride (KBF ₄ ), Sodium Fluoride (NaF), Sodium Bifluoride (NaHF ₂ ), Aluminum Fluoride (AlF ₃ ), Boron Fluoride Acids (HBF ₄ ), lithium fluoride (LiF), calcium fluoride (CaF ₂ ), and the like, and these may be used alone or in combination of two or more thereof.

The fluorine compound may be included in an amount of 0.01 to 2% by weight in 100% by weight of the etching liquid composition, preferably 0.01 to 1% by weight. In this content range, the titanium film is etched in an appropriate amount and an excellent etching profile can be obtained. If the content is less than 0.01% by weight, the etching rate of the titanium film may be lowered, and residues may occur. If the content is more than 2% by weight, the substrate may be damaged, such as glass, and the insulating film, such as a silicon film.

The chlorine compound is a compound capable of dissociating into chlorine ions in the etching liquid composition. It is an auxiliary oxidant for etching the copper film and controls the local over-erosion of the persulphate copper film by competing reactions against the etching of the copper film with the persulfate. It is the component to control the etching speed and the taper angle. Specific examples include hydrochloric acid (HCl), sodium chloride (NaCl), potassium chloride (KCl), ammonium chloride (NH ₄ Cl) and the like, these may be used alone or in combination of two or more.

The chlorine compound may be included in 0.001 to 3% by weight in the total 100% by weight of the etching liquid composition, preferably 0.001 to 1.5% by weight. Within this content range, the etching rate of the copper film can be optimized. If the content is less than 0.001% by weight, it may cause defects by local erosion of the copper film by the etching solution.If the content is more than 3% by weight, the number of treatments for a certain content may be reduced, and the etching rate may be excessively increased, resulting in poor etching profiles. have.

Inorganic acids, salts thereof or mixtures thereof are auxiliary oxidants for etching copper films and titanium. Specific examples include nitric acid, sulfuric acid, phosphoric acid, perchloric acid and salts thereof, and these may be used alone or in combination of two or more thereof.

The inorganic acid, salts thereof, or mixtures thereof may be included in an amount of 1 to 10% by weight, preferably 2 to 7% by weight, in 100% by weight of the total amount of the etchant composition. In this content range, the copper film and the titanium film are etched in an appropriate amount, and an excellent etching profile can be obtained. If the content is less than 1% by weight, the etching rate may be lowered, resulting in poor etching profiles and residues. If the content is more than 10% by weight, overetching may occur and cracks may occur in the photoresist. The etchant composition may penetrate and short the wiring.

The cyclic amine compound is a component that controls the etching rate and forms a profile during etching of the copper film. Specific examples include 5-aminotetrazole, tolytriazole, benzotriazole, methylbenzotriazole, An imidazole compound, an indole compound, a purine compound, a pyrazole compound, a pyridine compound, a pyrimidine compound, a pyrrole compound, a pyrrolidine compound, a pyrroline compound, and the like. It can be mixed and used.

The cyclic amine compound may be included in 0.3 to 5% by weight in the total 100% by weight of the etchant composition, preferably 0.5 to 3% by weight. In this content range, it is possible to form an appropriate copper etch rate and taper angle, and to control the side etch amount. If the content is less than 0.3% by weight, it is difficult to sufficiently control the etching rate of copper, and overetching may occur. When the content is more than 5% by weight, the etching rate of copper may be lowered, thereby increasing the etching time in the process, thereby reducing productivity.

An organic acid, a salt thereof, or a mixture thereof is a component that can control a taper angle of the copper film and adjust an etching rate so that a constant etching profile can be maintained when the treated sheet is processed over time in order to obtain a desired side etching. In addition, the chelating action with the etched metal ions to prevent affecting the etching liquid composition also serves to increase the number of treatment for a certain amount.

Specific examples of organic acids, salts thereof, or mixtures thereof include acetic acid, imino diacetic acid, ethylenediaminetetraacetic acid, butanoic acid, citric acid, isocitric acid, formic acid, gluconic acid, glycolic acid, malonic acid, oxalic acid, pentanic acid, sulfobenzoic acid, Succinic acid, sulfosuccinic acid, salicylic acid, sulfosalicylic acid, benzoic acid, lactic acid, glyceric acid, malic acid, tartaric acid, propenoic acid, and the like. In addition, examples of the salts of the organic acids include potassium salts, sodium salts and ammonium salts of the above organic acids. These can be used individually or in mixture of 2 or more types.

The organic acid, a salt thereof, or a mixture thereof may be included in an amount of 1 to 10% by weight, preferably 2 to 7% by weight, in 100% by weight of the total amount of the etchant composition. If the content is less than 1% by weight, it is difficult to maintain a constant etching profile over time, and the increase of the number of treatments is insignificant. If the content is more than 10% by weight, the side etching increases due to overetching and more. It is uneconomical because there is no effect of increasing the number of treatments above.

The p-toluenesulfonic acid is a component that can be stored for a long period of time to prevent the change in the etching properties by changing its composition over time after the preparation of the etching solution composition, improve the storage stability.

The p-toluenesulfonic acid may be included in an amount of 0.1 to 5% by weight in 100% by weight of the total etching solution composition, preferably 0.5 to 3% by weight. If the content is less than 0.1% by weight, it is difficult to prevent the change of its composition with time, and when the content is more than 5% by weight, overetching may occur, resulting in poor etching profiles.

The kind of water is not specifically limited, It is preferable that it is deionized distilled water, More preferably, it is preferable that the specific resistance value is 18 kPa / cm or more as deionized distilled water for a semiconductor process.

Water may be included in the balance in a total of 100% by weight of the etchant composition.

The etchant composition of the present invention may further include one or more additives such as an etching regulator, a surfactant, a metal ion sequestrant, a corrosion inhibitor, a pH regulator, etc. together with the above components.

The etchant composition of the present invention configured as described above does not cause disproportionation reaction and thus has excellent storage stability without degrading the composition itself or sudden change of composition with time, and not only double metal film in which copper film and titanium film are laminated, but also these two or more times. It is particularly useful for uniformly batch etching multiple stacked metal films at a high etching rate. Through this, the etching process can be simplified and productivity can be improved, and excellent etching characteristics can be obtained.

In addition, the etchant composition of the present invention comprises a persulfate and a fluorine compound, which is a main component for etching the copper film and the titanium film, and a component for etching the metal oxide film, respectively, and a copper film / titanium film is used as a source / drain electrode, and a-ITO Indium tin oxide (IZO) or indium zinc oxide (IZO) may be used for the batch etching of the source / drain electrode and the pixel electrode.

In addition, the etchant composition of the present invention can be used not only for the manufacture of flat panel displays such as liquid crystal displays but also for the manufacture of memory semiconductor displays and the like.

The TFT-LCD may be manufactured by a method including etching a multiple metal film of a copper film / titanium film by using the etching solution composition of the present invention to form a pattern of a metal wiring.

The manufacturing method of TFT-LCD is not specifically limited. For example, forming a multi-metal film composed of a copper film / titanium film which is a wiring material for the source / drain electrodes on the substrate; Forming a photoresist in an optional region on the formed copper film / titanium film; And etching the copper film / titanium film with the etchant composition of the present invention using the formed photoresist as a mask to form a pattern of a metal wiring.

According to the TFT-LCD manufacturing method configured as described above, excellent metal wiring, that is, source / drain wiring, can be easily formed, and the size of the TFT-LCD can be achieved.

Hereinafter, preferred examples are provided to aid the understanding of the present invention, but these examples are merely illustrative of the present invention and are not intended to limit the scope of the appended claims. It is apparent to those skilled in the art that various changes and modifications can be made to the present invention, and such modifications and changes belong to the appended claims.

Example

Example 1

10% by weight of ammonium persulfate (APS), 0.5% by weight of ammonium bifluoride (ABF), 0.05% by weight of ammonium chloride (NH ₄ Cl), ₃ % by weight of nitric acid (HNO ₃ ), 5-aminotetra 1% by weight of azole (aminotetrazole (ATZ), 3% by weight of ammonium acetate (AA), 5% by weight of acOH, 2% by weight of p-toluene sulfonic acid (PTA) and residual water This mixed etchant composition was prepared to be 5 kg.

Example  2, Comparative example  1-6

The same procedure as in Example 1, except that the ingredients and contents as shown in Table 1 were used.

division Content (% by weight) APS ABF NH ₄ Cl HNO ₃ ATZ AA AcOH PTA water Example 1 10 0.5 0.05 3 One 3 5 2 Balance Example 2 5 0.5 0.001 5 One 3 5 2 Balance Comparative Example 1 5 0.5 - 3 One 3 5 2 Balance Comparative Example 2 7 0.5 0.05 3 One - - - Balance Comparative Example 3 5 0.5 0.01 - One 3 5 2 Balance Comparative Example 4 15 0.5 0.01 - One 3 - 2 Balance Comparative Example 5 10 0.5 0.1 3 One 3 5 - Balance Comparative Example 6 10 0.5 4 3 One 3 5 2 Balance APS: ammonium persulfate
ABF: ammonium bifluoride
ATZ: 5-aminotetrazole
AA: ammonium acetate
AcOH: acetic acid
PTA: p-toluenesulfonic acid

Test Example

1. Etch Characteristic Evaluation

A silicon layer is deposited on glass, a copper film and a titanium film are stacked on the silicon layer in order, and a substrate is patterned on a titanium film in a uniform shape by using a diamond knife. The specimen was cut into pieces.

The etchant composition prepared in a spray-type etching system (ETCHER (TFT), manufactured by SEMES) was placed, and the temperature was set at 30 캜 and then heated. Thereafter, the etching process was performed after the temperature reached 30 占 0.1 占 폚. The total etching time was performed at 50% based on the EPD time (Ending Point detector, EPD). When the etching was completed, the specimen was injected. After the etching was completed, the substrate was washed with deionized water, dried using a hot air drier, and photoresist was removed using a photoresist stripper. After washing and drying, the electron scanning microscope (SEM) (S-4700, HITACHI Co., Ltd.) was used to evaluate the etching characteristics such as critical dimension (CD), taper angle, and metal film damage.

<Evaluation Criteria>

○: Excellent (CD Skew ≤ 1 μm, taper angle: 40-60 °)

(Triangle | delta): Good (1 micrometer <CD Skew <2 micrometers, taper angle: 30-70 degrees)

X: defective (metal film disappeared and residues generated, taper angle: 80 ° or more)

2. Evaluation of Storage Stability (Storage Characteristics)

A reference etch test was conducted with the prepared etchant composition, and the remaining etchant composition was stored at 25 ° C. for a planned date (based on 5 days). Thereafter, using the stored etchant composition was etched again under the same conditions as in the above test to compare with the results in the reference etching test and to evaluate the storage stability.

<Evaluation Criteria>

○: Excellent (excellent etching profile after 3 days)

X: Defective (less than or equal to etching profile after 3 days)

3. Valuation of treatment quantity

A reference etch test was performed using the prepared etchant composition, and 4,000 ppm of copper powder was added to the reference test etchant to completely dissolve it. Subsequently, etching was performed again, and when the difference occurred because the variation of the side etching exceeded 10% compared to the reference etching test, the difference was evaluated as bad.

<Evaluation Criteria>

○: excellent (10% or less of side etching variation)

×: defective (side etching amount more than 10%)

division Etch characteristics Storage stability Processing Example 1 ○ ○ ○ Example 2 ○ ○ ○ Comparative Example 1 △ ○ × Comparative Example 2 ○ × × Comparative Example 3 × × Comparative Example 4 × ○ × Comparative Example 5 ○ × × Comparative Example 6 × × ×

As shown in Table 2, the etching liquid composition of Examples 1 to 2 according to the present invention can obtain an excellent etching profile during batch etching of a double metal film composed of a copper film / titanium film, without damaging the glass substrate and the silicon layer and Excellent etching characteristics without loss of film and residue were shown. In addition, it was confirmed that the storage stability and treatment number characteristics were also excellent.

On the other hand, Comparative Example 1 containing no chlorine compound was able to secure some etching characteristics and storage stability, but the number of treatment was poor, Comparative Example 2 containing no organic acid / salt and p-toluenesulfonic acid storage stability and treatment The number of sheets was poor, and Comparative Examples 3 and 4, which did not contain an inorganic acid, had very low etching rates, resulting in poor etching and residues, and thus, poor number of sheets. In addition, Comparative Example 5, which does not contain p-toluenesulfonic acid, had poor storage stability and treatment number characteristics, and Comparative Example 6, which contained excessive amounts of chlorine compounds, had poor storage stability and very high etching taper angle, resulting in poor etching characteristics. .

Claims (12)

5-20 wt% persulfate;
0.01 to 2% by weight of a fluorine compound;
0.001 to 3 weight percent of a chlorine compound;
1 to 10% by weight of inorganic acid, salts thereof or mixtures thereof;
0.3 to 5% by weight of the cyclic amine compound;
1 to 10% by weight of organic acid, salt thereof or mixture thereof;
0.1 to 5% by weight of p-toluenesulfonic acid; And
Etching liquid composition of the copper film / titanium film containing a residual amount of water.
The etchant composition of claim 1, wherein the persulfate is at least one member selected from the group consisting of ammonium persulfate, sodium persulfate and potassium persulfate.
The fluorine compound of claim 1, wherein the fluorine compound is hydrofluoric acid, ammonium fluoride, ammonium bifluoride, ammonium fluoride, potassium fluoride, potassium bifluoride, potassium borofluoride, sodium fluoride, sodium bifluoride, aluminum fluoride, boric fluoride, lithium fluoride and fluoride An etching liquid composition of at least one copper film / titanium film selected from the group consisting of calcium.
The etchant composition of claim 1, wherein the chlorine compound is at least one selected from the group consisting of hydrochloric acid, sodium chloride, potassium chloride, and ammonium chloride.
The etchant composition of claim 1, wherein the inorganic acid is at least one selected from the group consisting of nitric acid, sulfuric acid, phosphoric acid, or perchloric acid.
The compound according to claim 1, wherein the cyclic amine compound is 5-aminotetrazole, tolytriazole, benzotriazole, methylbenzotriazole, imidazole compound, indole compound, purine compound, pyrazole compound, pyridine compound And pyrimidine compounds, pyrrole compounds, pyrrolidin compounds, and pyroline compounds. An etching liquid composition of at least one copper film / titanium film selected from the group consisting of compounds.
The method of claim 1, wherein the organic acid is acetic acid, imino diacetic acid, ethylenediamine tetraacetic acid, butanoic acid, citric acid, isocitric acid, formic acid, gluconic acid, glycolic acid, malonic acid, oxalic acid, pentanic acid, sulfobenzoic acid, succinic acid, sulfostone An etching liquid composition of a copper film / titanium film which is at least one selected from the group consisting of citric acid, salicylic acid, sulfosalicylic acid, benzoic acid, lactic acid, glyceric acid, malic acid, tartaric acid and propene acid.
The etchant composition of claim 1, wherein the salt of the organic acid is a potassium salt, a sodium salt, or an ammonium salt.
The etchant of claim 1, wherein the copper film is a copper single film or a copper alloy film containing at least one selected from the group consisting of copper, aluminum, magnesium, manganese, beryllium, hafnium, niobium, tungsten, and vanadium. Composition.
The etchant composition of claim 1, wherein the titanium film is a titanium single film.
The etchant composition according to claim 1, wherein the copper film / titanium film is a multilayer film in which a copper film and a titanium film are alternately stacked one or more times.
A method of manufacturing a thin film transistor comprising etching a copper film / titanium film with the etching liquid composition of any one of claims 1 to 11 to form a pattern of a metal wiring.