KR20110076468A - Etchant for metal film of liquid crystal display - Google Patents

Abstract

PURPOSE: An etchant for a metal film of a liquid crystal display is provided to maintain stable state without the composition change of etchant, to minimize lifetime reduction and capacity reduction, and to secure the uniformity of etching. CONSTITUTION: An etchant for a metal film of a liquid crystal display for etching a metal layer functioning as an electrode and a signal line including copper comprises: copper ions as an oxidizing agent; halogen ions; amines compound; organic acids; and etching inhibitors. The concentration of the copper ion is 0.5~20 weight%. The concentration of the halogen ion is 0.001~10 weight%. The concentration of the amines compound is 3~40 weight%. The concentration of the organic acid is 0.5~35 weight%. The concentration of the etching inhibitor is 0.001~5 weight%.

Description

Etchant for metal film of Liquid Crystal Display

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etchant used to form electrodes and signal lines made of metal films in liquid crystal displays.

Liquid crystal displays, along with plasma display panels (PDPs) and field emission displays (FEDs), are used as next-generation displays in the fields of mobile phones, computer monitors, and televisions. Be in the spotlight. Among the liquid crystal display devices, TFT (Thin Film Transister) liquid crystal display devices are provided with various electrodes and signal lines such as gate electrodes and signal lines, source electrodes and signal lines, drain electrodes and signal lines, and transmit signals to devices. I am in charge.

Recently, as a liquid crystal display device is enlarged in size and in high resolution, aluminum (Al) has been replaced by copper (Cu) having excellent electrical characteristics as a material of a metal film constituting an electrode and a signal line. In this case, a form of a single layer metal film made of only copper or a form of a double layer metal film in which titanium (Ti) or a titanium alloy or tantalum (Ta) or a tantalum alloy and copper are laminated is used.

According to the related art, the method of etching the above-described double layer metal film is performed by using an etching solution containing hydrogen peroxide (H ₂ O ₂ ) as a basic oxidant and nitrogen compounds such as fluorine ions (F ⁻ ), sulfuric acid, and amine. It was a way to regulate.

However, when hydrogen peroxide is used as an oxidizing agent, the decomposition of hydrogen peroxide causes a decrease in the life of the etching solution and a decrease in the etching capacity, and a problem such as a change in the etching factor and the etching rate according to the composition of the etching solution occurs. In addition, there is a problem that a safety accident due to instability of hydrogen peroxide occurs, there is a situation that a non-hydrogen peroxide-based etching solution that does not use hydrogen peroxide is required.

An object of the present invention is to provide a metal film etching solution of a liquid crystal display device that can solve the instability of the hydrogen peroxide-based etching solution itself.

The metal film etching solution of the liquid crystal display device according to the present invention for achieving the above object is to etch a metal film containing copper in the liquid crystal display device to function as an electrode and a signal line, copper ions as an oxidant and halogen ions And an amine compound, an organic acid, and an etching inhibitor.

According to the present invention, since copper ions other than hydrogen peroxide are used as the oxidizing agent, a very stable state can be maintained without changing the composition of the etching solution, and life reduction and capacity reduction can be minimized as the etching proceeds. And the damage of the photoresist layer after the etching by etching liquid does not generate | occur | produce, and metal residue does not generate | occur | produce on the surface of a glass substrate. In addition, since the uniformity of etching can be sufficiently secured, it can be applied to the etching of electrodes or signal lines having a fine width of about 3 to 50 µm.

The etchant according to an embodiment of the present invention is to etch a metal film containing copper in the liquid crystal display and functions as an electrode and a signal line. As an example of the metal film, one selected from the group consisting of titanium and titanium alloys and tantalum and tantalum alloys may be in the form of a double layer metal film in which copper is laminated. Etching liquid contains a copper ion, a halogen ion, an amine compound, an organic acid, and an etching inhibitor.

Copper ions act as an oxidant of copper contained in the metal film. Copper ions may be present in various forms in the etchant. For example, copper ions may be in the form of copper chloride, copper bromide, copper sulfate, copper carbonate, copper acetate, copper oxide, or the like. have.

 The oxidation effect of copper ions can be higher when in the form of a copper-complex, than with divalent copper ions alone, and the shape of the copper-composite affects the etch rate. Therefore, depending on which copper-compositing compound is selected, the oxidation effect and the etching rate can be controlled as desired.

The concentration of copper ions is preferably 0.5 to 20% by weight. More preferably, the concentration of copper ions is 1 to 15% by weight. If copper ions are present at concentrations lower than 0.5% by weight, it can be difficult to act as an oxidant. On the other hand, when copper ions are present at a concentration higher than 20% by weight, divalent copper ions can be reduced to monovalent copper ions and deposited on the copper surface of the metal film. For this reason, an uneven etching state may appear on the surface of a metal film, or a stain may arise.

As described above, according to the present embodiment, unlike the related art, copper ions are used as oxidants instead of hydrogen peroxide, and thus, the above-described problems of using hydrogen peroxide can be solved.

Halogen ions increase the solubility of copper in the metal film and play an important role in maintaining a stable state of the etching solution. In addition, when the metal film is in the form of a double layer of copper-titanium, the halogen ions serve to increase the dissolution of titanium and the interlayer portion of the copper-titanium at the center of the two layers in dissolving the double layered metal film.

Halogen ions can be applied in the form of hydrochloric acid, bromic acid and iodic acid. Application is possible.

The concentration of halogen ions is preferably 0.001 to 10% by weight. More preferably, the concentration of halogen ions is 0.01 to 6% by weight. If the halogen ions are present at concentrations lower than 0.001% by weight, the etching rate may be too slow. On the other hand, if halogen ions are present at concentrations higher than 10% by weight, due to too fast etch rates, it is impossible to maintain a proper working zone.

Amine compounds act as complex compounds capable of dissolving copper in the metal film. The amine compounds may be in the form of compounds which are easily dissolved in water. For example, the amine compounds include n-amylamine, ethylenediamine, t-butylamine, 1,6-diaminohexane, and monoethanolamine. (monoethanolamine), diethanolamine, triethanolamine, triethanolamine, propanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine N-diethylethanolamine), cyclohexylamine, dicyclohexylamine, diisopropanolamine, and the like. The amine compounds described above can be applied alone or in combination.

It is preferable that the density | concentration of an amine compound is 3-40 weight%. More preferably, the concentration of the amine compound is 5 to 30% by weight. If the amine compound is present at a concentration lower than 3% by weight, the etching rate is too slow. On the other hand, when the amine compound is present at a concentration higher than 40% by weight, the etching rate may be too fast or the undercut phenomenon may increase.

The organic acid serves as a buffer for the etching solution to maintain a proper pH, and forms a complex with copper to increase the stability of copper ions in the etching solution. Organic acids can be applied in various forms. For example, organic acids include formic acid, acetic acid, propionic acid, butyric acid, acrylic acid, crotonic acid, oxalic acid and malonic acid. (malonic acid), maleic acid, maleic acid, succinic acid, glutaric acid, adipic acid, glycolic acid, lactic acid, malic acid malic acid), citric acid, and the like.

The organic acid may be applied alone or in combination. The concentration of the organic acid is preferably 0.5 to 35% by weight. More preferably, the concentration of organic acid is 1 to 20% by weight. If the organic acid is present at a concentration lower than 0.5% by weight, it is difficult to serve as a buffer and cannot maintain a proper pH. On the other hand, when the organic acid is present at a concentration higher than 35% by weight, precipitation of the organic acid and solubility of copper ions may decrease, and thus the etching rate may be slowed.

The etching inhibitor is for controlling the etching rate of the metal film and improving the roughness of the surface. Etch inhibitors include benzotriazole, imidazole, aminotetrazole, polyvinylpyrrolidine, ethyleneglycol, polyethyleneglycol, polyvinylalcohol , Ethylene oxide / propylene oxide copolymer (ethylene oxide / propylene oxide copolymer) may be applied.

The concentration of the etching inhibitor is preferably 0.001 to 5% by weight. More preferably, the concentration of the etching inhibitor is 0.01 to 1% by weight. If the etch inhibitor is present at a concentration lower than 0.001% by weight, it will not function properly as an etch inhibitor. On the other hand, when the etching inhibitor is present in a concentration higher than 5% by weight, there is a problem that the etching rate is sharply reduced due to the strong inhibitory action. In addition, the etchant contains water so as to exist in the form of an aqueous solution.

Hereinafter, the effect of the etching solution composed of the above-described components will be described. In detail, the etching solution according to Example 1 and the etching solution according to Example 2 were prepared at the ratios of Table 1 below. And the etching liquid which concerns on a comparative example was prepared by the ratio of the following Table 2 for the comparison with Example 1, 2.

Specimens etched by each etchant were sequentially deposited titanium and copper on a glass substrate by deposition, a photoresist (PR) layer formed on the stacked copper layers, and then a photolithography process was completed. Prepared in the form. In addition, the specimen size was prepared 20mm x 20mm (area). For these specimens, spray etching was carried out for 60 seconds at a temperature of 1.4 kgf / cm ² at a temperature of 30 ° C.

Example 1 Example 2 ingredient Ratio (% by weight) ingredient Ratio (% by weight) Copper chloride 5 wt% Copper acetate 8 wt% Triethanolamine 30 wt% N, N-dimethylethanolamine 30 wt% Glacial acetic acid 10 wt% Acrylic acid 8 wt% halogen 1 wt% halogen 2 wt% Etching inhibitor 0.1 wt% Etching inhibitor 0.1 wt% water 53.9% by weight water 51.9 wt% pH: 8.8 pH: 9.2

Comparative example         ingredient      Ratio (% by weight) Hydrogen peroxide 6 wt% Sulfuric acid 12 wt% Monoethanolamine 2 wt% halogen 1 wt% Fruit Stabilizer 0.5 wt% water 78.5 wt% pH: 2.8

According to the experimental results, in both Examples 1 and 2, the double layer metal film could be etched clean enough to satisfy the set conditions. At this time, the etching rate for the copper is about 0.30 ~ 0.35㎛ / min. The damage of the photoresist layer did not occur. Titanium residue remaining on the surface of the glass substrate was not observed under a microscope (× 1,000). When the photoresist layer was stripped, the metal film corresponding to the electrode and the signal line maintained a uniform etching form.

In addition, after performing the primary etching with the etching liquids according to Examples 1 and 2, and performing the secondary etching in a state where 120 hours, 240 hours, and 360 hours had elapsed, the etching rate did not change at all. It was confirmed that the etchant maintained a very stable state. That is, it was confirmed that the life of the etching solution and the decrease in the etching capacity did not occur without changing the composition of the etching solution.

As a comparison experiment, the etching liquid according to the comparative example was etched in the same manner as in Examples 1 and 2. The etching rate for copper is about 0.25-0.30 μm / min. The damage of the photoresist layer did not occur. Fine titanium residue remaining on the surface of the glass substrate was observed under a microscope (× 1,000), but there was no significant difference from Example 1.2.

However, in the secondary etching for investigating the stability of the etching solution, an increase in etching time was observed by about 10% after 120 hours and about 25% after 240 hours. After 360 hours of secondary etching, the etching rate increased by 40% and titanium residues were easily found on the surface of the glass substrate. In addition, damage to the photoresist layer was also observed.

This result is due to the decomposition of hydrogen peroxide, which results in a change in the composition of the etching solution, which makes the working process difficult and reduces the uniformity of the etching. In addition, since the composition change of the etching solution requires the addition of additional etching solution, the production cost is increased.

On the other hand, since the etching solution according to the present embodiment can maintain a very stable state by using copper ions rather than hydrogen peroxide as an oxidizing agent without changing the composition, all the problems caused by applying the etching solution of the comparative example can be solved. In addition, according to the present embodiment, since the uniformity of etching can be sufficiently secured, the present invention can also be applied to the etching of electrodes or signal lines having a fine width of about 3 to 50 µm.

Although the present invention has been described with reference to one embodiment shown in the accompanying drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Could be. Accordingly, the true scope of protection of the present invention should be determined only by the appended claims.

Claims (4)

In the liquid crystal display device for etching a metal film containing copper to function as an electrode and a signal line, A metal film etching liquid of a liquid crystal display device comprising copper ions as an oxidant, halogen ions, amine compounds, organic acids, and an etching inhibitor. The method of claim 1, The concentration of the copper ions is 0.5 to 20% by weight, the concentration of the halogen ions is 0.001 to 10% by weight, the concentration of the amine compounds is 3 to 40% by weight, and the concentration of the organic acid is 0.5 to 35% by weight. And the etching inhibitor has a concentration of 0.001 to 5 wt%, and the remainder of the etching solution is filled with water. 3. The method of claim 2, The concentration of the copper ions is 1 to 15% by weight, the concentration of the halogen ions is 0.01 to 6% by weight, the concentration of the amine compounds is 5 to 30% by weight, and the concentration of the organic acid is 1 to 20% by weight. And the concentration of the etching inhibitor is 0.01 to 1% by weight of the metal film etching solution of the liquid crystal display device. The method according to any one of claims 1 to 3, The metal film is a metal film etching solution of the liquid crystal display device, characterized in that in the form of a double layer metal film in which copper and one selected from the group consisting of titanium and titanium alloys, tantalum and tantalum alloys.