KR20100021376A - Etching liquid composition for transparent conductive film - Google Patents

Abstract

PURPOSE: An etching liquid composition for a transparent conductive film is provided to extend the lifetime of etchant by suppressing crystal precipitation of indium oxalate in an etching process of a transparent conductive film. CONSTITUTION: An etching liquid composition for a transparent conductive film comprises oxalic acid and an alkaline compound excluding triethanolamine. The alkaline compound is at least one or two selected from the group consisting of quaternary ammonium hydroxides, hydroxide of alkali metal, alkanolamines excluding triethanolamine, and hydroxylamines.

Description

Etching liquid composition for transparent conductive films {ETCHING LIQUID COMPOSITION FOR TRANSPARENT CONDUCTIVE FILM}

This invention relates to the etching liquid composition for transparent conductive films used for a liquid crystal display (LCD), an electroluminescence display (ELD) display element, etc.

Examples of transparent conductive films used for liquid crystal displays, electroluminescent display display devices, and the like include indium oxide (ITO), indium zinc oxide (IZO), indium oxide, stone oxide, and zinc oxide, among others, ITO film and IZO. Membranes are widely used. As a method of patterning a transparent conductive film, a method of forming an electrode pattern by forming a resist pattern by a photolithography method after forming a transparent conductive film on a substrate such as glass by a sputtering method or the like and etching the transparent conductive film is common. .

As an etching solution of a transparent conductive film, indium oxides, such as (1) iron chloride solution, (2) aqueous solution of iodide, (3) aqueous solution of phosphate, (4) hydrochloric acid and nitric acid (aqua regia), and (5) aqueous solution of oxalic acid, are dissolved. Etching liquids containing components have been proposed.

Conventionally, as the ITO film, a polycrystalline ITO film having good basic characteristics as a transparent conductive film such as specific resistance and transmittance has been used, but in recent years, the processing precision has been improved and the process temperature has been lowered in order to increase the size, high precision, and high performance of the display device. In order to improve the surface flatness and the like, an amorphous ITO film or an IZO film has been used as a transparent conductive film that satisfies these requirements.

As an etching solution for transparent conductive films such as amorphous ITO films and IZO films, an oxalic acid aqueous solution which is inexpensive, excellent in stability, has a practical etching rate, and has little damage to Al wiring is widely used. However, in the etching of the transparent conductive film by the oxalic acid aqueous solution, there is a problem that crystals of indium oxalate are easily precipitated.

Usually, since etching liquid is circulated in an etching apparatus and used repeatedly, when a transparent conductive film is etched using the etching liquid containing oxalic acid, the indium concentration in an etching liquid rises and crystals of indium oxalate tend to precipitate. Once precipitated, crystal growth proceeds as a nucleus to form coarse, large crystals that adhere to the device. As a result, problems such as malfunction of the apparatus, clogging of the filter, damage to the substrate, and the like arise.

Since indium oxalate is an extremely poorly soluble salt, it is difficult to re-dissolve in the etching solution and also difficult to dissolve in water. For this reason, in order to remove the crystal which precipitated in the apparatus, after removing the etching liquid in a apparatus, it can only remove by manual methods, such as removal by dissolution by a chemical liquid, and it is related with the fall of a production volume and a production cost increase. In addition, the blind filter has no choice but to remove the crystals or replace the filter, which is also related to a decrease in production and an increase in production cost. Thus, in the etching of the transparent conductive film using the etching liquid containing oxalic acid, it is a big problem that crystal | crystallization of indium oxalate tends to precipitate.

As a countermeasure for this problem, use of a component that dissolves indium oxide other than the above-described oxalic acid can be cited. However, the iron chloride solution has a disadvantage that the amount of side etching is large and contains Fe, which adversely affects the semiconductor. In addition, the aqueous solution of iodine has a disadvantage of being expensive in addition to lack of stability because iodine is easily released. In addition, the aqueous solution of phosphoric acid has a drawback of damaging the A1 wiring and easily causing etching residues. In addition, the hydrochloric acid-nitric acid mixture (aqua regia) has a drawback that the change over time is difficult and the process control is difficult, and thus distribution is impossible.

Moreover, when etching transparent conductive films, such as an amorphous ITO film | membrane and an IZO film | membrane by the etching liquid which has oxalic acid as a main component, there exists a problem that an etching residue tends to occur. As a method for solving this problem, the present inventors propose an etching solution composition for an ITO film containing one or two or more compounds selected from the group consisting of an oxalic acid, a polysulfonic acid compound, and a polyoxyethylene-polyoxypropylene block copolymer. It was (patent document 1). Moreover, the etching liquid composition for ITO membranes containing oxalic acid, aminocarboxylic acid, or triethanolamine (patent document 2), the etching agent for amorphous ITO membranes containing oxalic acid and carboxylic acid (patent document 3), a perfluoroalkyl group containing phosphate ester salt, Although oxalic acid, the etching liquid composition for ITO membranes and IZO membranes containing water (patent document 4), the ITO membrane containing oxalic acid and a fluorine-type surfactant, the etching liquid composition for IZO membranes (patent document 5), etc. are proposed, Although the etching liquid contained has a practical etching rate and the effect is recognized for the prevention of an etching residue, the problem of crystal precipitation of indium oxalate mentioned above is not recognized at all, and it is an unsolved state.

Moreover, as an etching solution which does not contain oxalic acid, the etching agent composition for amorphous ITO membranes which consists of aqueous solution containing a sulfamic acid and polyoxyethylene alkyl ether sulfate, polyoxyethylene alkylphenyl ether sulfate, or polyoxyalkylene alkyl ether phosphoric acid ester ( Although Patent Document 6) and the like have been proposed, the etching solution containing no oxalic acid does not precipitate crystals of indium oxalate, and thus the effect is recognized for the prevention of etching residues, but the etching rate is slower than that of the aqueous solution containing oxalic acid. There is a problem that the yield decreases.

As described above, the conventional etching solution containing, as a main component, an inorganic acid that dissolves indium oxide other than oxalic acid has a large problem in use in terms of etching characteristics and stability of the etching solution, and is comparable to an etching solution containing oxalic acid as a main component. There is no etching liquid having excellent characteristics. In addition, in the nickname which has oxalic acid as a main component, the etching liquid which maintains the outstanding characteristic and can suppress crystal precipitation of indium oxalate does not exist yet.

Therefore, as a countermeasure against crystallization when the etching liquid mainly containing oxalic acid is used in the etching process of the transparent conductive film containing indium, the method of regenerating the etching liquid after use by filtration through the nanofiltration film, and regular maintenance management of the apparatus It is a phenomenon that the countermeasure is taken only in the apparatus side, such as the structure of an apparatus which crystal | crystallization and crystal | crystallization are difficult to precipitate (patent document 7 and nonpatent literature 1).

[Patent Document 1] Japanese Patent Laid-Open No. 2002-164332

[Patent Document 2] Japanese Patent Laid-Open No. 2002-033304

[Patent Document 3] Japanese Patent Laid-Open No. 2003-306676

[Patent Document 4] Japanese Patent Laid-Open No. 2005-116542

[Patent Document 5] Japanese Patent Laid-Open No. 2005-244083

[Patent Document 6] Japanese Patent Laid-Open No. 2002-367974

Patent Document 7: Japanese Patent Laid-Open No. 2006-013158

[Non-Patent Document 1] First Printing, December 17, 2007, Published by Information Agency, Ltd. "Current Collection of Transparent Conductive Films" p556-557

Therefore, the subject of this invention is the etching liquid for transparent conductive films which can prevent the precipitation of the crystal of indium oxalate, and contributes to the improvement of production amount and the cost of production in the etching process of transparent conductive films, such as amorphous ITO and IZO used for a liquid crystal display etc. It is in providing a composition.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, the present inventors carried out earnest research, and the etching liquid composition for transparent conductive films containing an oxalic acid and an alkaline compound has the same outstanding characteristic as the etching liquid which has oxalic acid as a main component, and simultaneously crystallizes indium oxalate As a result of finding the thing which can suppress an exit and having researched, it came to complete this invention.

That is, this invention relates to the etching liquid composition for transparent conductive films containing oxalic acid and an alkaline compound (except triethanolamine).

In addition, the present invention is the transparent compound, wherein the alkaline compound is one or two or more selected from the group consisting of quaternary ammonium hydroxides, hydroxides of alkali metals, alkanolamines (except triethanolamine), and hydroxylamines. It relates to the etching liquid composition for conductive films.

Moreover, this invention relates to the said etching liquid composition for transparent conductive films whose pH is 1.1-5.0.

In addition, the present invention relates to the etching liquid composition for transparent conductive film comprising one or two or more compounds selected from the group consisting of polysulfonic acid compounds, polyoxyethylene-polyoxypropylene block copolymers and sulfonate type anionic surfactants. It is about.

Moreover, this invention relates to the said etching liquid composition for transparent conductive films used for the etching of the transparent conductive film containing indium oxide.

Moreover, this invention relates to the etching method of a transparent conductive film using the said etching liquid composition for transparent conductive films.

It is considered that the cause of crystallization of indium oxalate tends to be due to the low solubility of indium in the oxalic acid aqueous solution. Investigations of the present inventors have revealed that the amount of indium dissolved in an aqueous solution of oxalic acid is about 300 ppm, and crystals of indium oxalate are more likely to precipitate at higher concentrations. That is, it is considered that increasing the dissolution amount of indium in the oxalic acid aqueous solution is related to suppressing crystal precipitation of indium oxalate.

Although the reason why the etching liquid composition for transparent conductive films of this invention contains an alkaline compound suppresses crystal precipitation of indium oxalate is not necessarily obvious, as a pH increases in a liquid, OH group compared with oxalic acid with respect to indium It is considered that it is a condition that complex compounds with amines and quaternary ammonium are likely to be formed, production of indium oxalate is suppressed, and as a result, the amount of dissolution of indium increases.

By the etching liquid composition for transparent conductive films of this invention, since crystal precipitation of indium oxalate is suppressed in the etching process of a transparent conductive film, since the liquid life of an etching liquid is extended and crystal removal work is reduced, the productivity improvement is improved. And the production cost can be reduced.

The present invention will be described in detail below. The transparent conductive film of the present invention is a transparent conductive film made of indium tin oxide (ITO), indium zinc oxide (IZO), indium oxide, or the like, and particularly, a transparent conductive film made of an amorphous ITO film and an IZO film. Moreover, the etching liquid composition for transparent conductive films of this invention is an etching liquid composition used for the etching process of the said transparent conductive film in manufacturing processes, such as a liquid crystal display and an electroluminescent display.

The concentration of oxalic acid used in the etching liquid composition of the present invention is appropriately determined in consideration of the fact that the etching rate is practically sufficient, the crystal of oxalic acid is not precipitated, but is preferably 0.1 to 10% by weight, more preferably Is 0.3 to 8% by weight, particularly preferably 0.5 to 6% by weight. If the concentration of oxalic acid is low, the etching rate is lowered. If the concentration of oxalic acid is high, the crystal of oxalic acid tends to precipitate. If the concentration of oxalic acid is in the above range, a practical etching rate can be obtained, and the crystal of oxalic acid is precipitated. Therefore, it is preferable because there is no fear of causing trouble in storage and distribution.

Although the alkaline compound used for the etching liquid composition of this invention is selected in consideration of the indium dissolution amount, an etching rate, etc., the etching liquid composition of this invention is characterized by the small fall of the etching rate at the time of adding an alkali component, and indium dissolution is carried out. The balance between the amount and the etching rate is particularly important. As an alkaline compound used for the etching liquid composition of this invention, the quaternary ammonium hydroxide, the hydroxide of alkali metals, alkanolamines (except triethanolamine), hydroxylamine, etc. are mentioned typically.

Specifically, as quaternary ammonium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, choline, etc. are mentioned, for example.

Moreover, as hydroxide of alkali metals, sodium hydroxide, a calcium hydroxide, etc. are mentioned, for example.

Examples of alkanolamines include monoalkanolamines, dialkanolamines, and trialkanolamines other than triethanolamine. Examples of monoalkanolamine oils include monoethanolamine, 2-methylaminoethanol, 2-ethylaminoethanol, 2- (2-aminoethoxy) ethanol, 1-amino-2-propanol, monopropanolamine and dimethyl. Aminoethanol, salts thereof, and the like. Moreover, as dialkanolamine, diethanolamine, N-methyl diethanolamine, dibutanolamine, these salts, etc. are mentioned, for example. Among the alkanolamines, monoalkanolamines, dialkanolamines, and the like are preferable from the viewpoint of indium dissolution amount, etching rate, and the like, and more preferably monoalkanolamines and the like are particularly preferred. Preferably, monoethanolamine etc. are mentioned.

As the hydroxylamines, for example, hydroxylamine, N-methylhydroxylamine, N, N-dimethylhydroxylamine, N, N-diethylhydroxylamine, hydroxylamine sulfate, hydrochloride hydrochloride and the like These may be mentioned, Preferably hydroxylamine etc. are mentioned.

Moreover, these alkaline compounds may be included 1 type or 2 or more types according to a use.

Although the density | concentration of the alkaline compound used for the etching liquid composition of this invention is suitably determined in consideration of the amount of indium dissolution, the crystal precipitation of indium oxalate, the pH of the etching liquid composition, an etching rate, etc., Preferably it is 0.1-10 weight%, More preferably, it is 0.3-7 weight%, Especially preferably, it is 0.5-5 weight%. If the concentration of the alkaline compound is low, crystals of indium oxalate tend to be precipitated, and if the concentration is high, the etching rate tends to decrease. If the concentration of the alkaline compound is in the above range, the effect of preventing precipitation of crystals of indium oxalate and practical etching is sufficient. It is preferable because the speed can be obtained.

Although the pH of the etching liquid composition of this invention determines suitably in consideration of the amount of indium dissolution, crystal precipitation of indium oxalate, an etching rate, etc., Preferably it is 1.1-5.0, More preferably, it is 1.2-4.0, Especially preferably, Is 1.3 to 3.0. When the pH is low, crystals of indium oxalate tend to precipitate, and when the pH is high, the etching rate tends to decrease. If the pH is in the above range, a sufficient effect of preventing precipitation of crystals of indium oxalate and a practical etching rate can be obtained. desirable.

PH of the etching liquid composition of this invention WHEREIN: The pH of the composition of this invention containing an oxalic acid and an alkaline compound, and the pH by adding the alkaline compound at the time of comparing the pH of the composition of the same composition except not containing an alkaline compound. The amount of change ΔpH is appropriately determined in consideration of the amount of indium dissolved, crystal precipitation and etching rate of indium oxalate, and is appropriately adjusted by the type and concentration of the alkaline compound to be added.

The range of ΔpH is preferably 0.1 to 4.0, more preferably 0.3 to 3.0, and particularly preferably 0.5 to 2.0. When ΔpH is small, crystals of indium oxalate tend to be precipitated, and when ΔpH is large, the etching rate tends to be low. If ΔpH is within the above range, a sufficient effect of preventing precipitation of crystals of indium oxalate and a practical etching rate are preferable. .

The etching rate of the etchant tidal liquid of the present invention is appropriately controlled by the concentration of the oxalic acid, the type and concentration of the alkaline compound to be added, etc. in consideration of the processing time and uniform etching.

Moreover, the etching liquid composition of this invention can contain the component for removing an etching residue further in the range which does not prevent the said effect. As a component used for such an objective, a polysulfonic acid compound, a polyoxyethylene polyoxypropylene block copolymer, a sulfonate type | mold anionic surfactant, etc. are preferable.

As a polysulfonic acid compound, naphthalene sulfonic-acid formaldehyde condensate and its salt, polystyrene sulfonic acid and its salt, lignin sulfonic acid, its salt, etc. are mentioned, for example. As naphthalene sulfonic acid formaldehyde condensate and its salt, specifically, Lunox 1000C, 1500A, Ionet D-2, Samyang Leveron PHL (above, Dongbu Chemical Co., Ltd.), Rome PWA-40 (Sannofuco Corporation), Demol It is marketed under brand names such as N (Huwang), Polyti N-100K (Lion), and Laberin FH-P (Cheil Industries). As lignin sulfonic acid and its salt, it is marketed specifically by brand names, such as sorbor 9047K (Dong Bang Chemical Co., Ltd.) and San Extract (Japan Paper Chemicals Co., Ltd.). Among these polysulfonic acid compounds, containing metals such as sodium is not preferable when used for the electronic industry, and can be used by removing sodium by treating with an ion exchange resin or the like.

There are various types of polyoxyethylene-polyoxypropylene block copolymers depending on the compounding and molecular weight of polyoxyethylene and polyoxypropylene, and specifically, for example, New Fore PE series (Samyang Chemical) And Epan series (Cheil Industries Pharmaceutical Co., Ltd.).

Examples of the sulfonate type anionic surfactants include alkylbenzene sulfonic acid esters and salts thereof, such as dodecylbenzenesulfonic acid, alkyl sulfate esters and salts thereof, dialkyl esters and salts thereof of sulfobacic acid, polyoxyethylene alkyl ether sulfonic acid, and the like. The salt, polyoxyethylene aryl ether sulfonic acid, its salt, etc. are mentioned. Among them, polyoxyethylene alkyl ether sulfonic acid and salts thereof, polyoxyethylene aryl ether sulfonic acid and salts thereof are relatively preferable because they are relatively low in foaming, and are commercially available under the trade names of Nyucor Series (Japan Emulsifier Co., Ltd.). Moreover, you may contain these compounds 1 type or 2 or more types according to a use.

The concentration of the polysulfonic acid compound, polyoxyethylene-polyoxypropylene block copolymer, and / or sulfonate type anionic surfactant used in the etching solution composition of the present invention is preferably from the viewpoint of obtaining a sufficient etching residue removal effect. Is 0.0001 to 10% by weight, particularly preferably 0.001 to 10% by weight.

Moreover, the etching liquid composition of this invention can contain the component for further suppressing crystal precipitation of indium oxalate in the range which does not prevent the said effect. As a component used for such an objective, the water-soluble polymer which has a scale prevention effect is preferable.

Examples of the water-soluble polymers include polyacrylic acid, polymaleic acid, acrylic acid-maleic acid copolymers, acrylic acid-sulfonic acid copolymers, acrylic acid-styrene copolymers and salts thereof. Specifically, it is marketed under brand names such as Aquaric Series (Japan Catalyst Co., Ltd.), Aaron Series (Dong-A Synthetic Co., Ltd.), and Polyty Series (Lion Corporation). Among these water-soluble polymers, containing metals such as sodium is not preferable when used for the electronics industry, and can be used by a method of removing sodium by treating with an ion exchange resin or the like. Moreover, you may contain these water-soluble polymers 1 type, or 2 or more types according to a use.

The concentration of the water-soluble polymer used in the etching solution composition of the present invention is preferably 0.001 to 10% by weight, particularly preferably 0.01 to 10% by weight, from the viewpoint of obtaining sufficient crystal precipitation inhibiting effect. Moreover, the molecular weight of these water-soluble polymers becomes like this. Preferably it is 200-100,000, Especially preferably, it is 500-10,000.

The etching liquid composition of the present invention can be used at room temperature or by heating, and conditions are appropriately used so that a desired etching rate and etching time can be obtained.

As the etching method of the transparent conductive film using the etching liquid composition of this invention, the spray process which supplies an etching liquid on a board | substrate with a spray nozzle, the dipping process which immerses a board | substrate directly in an etching liquid, shakes a board | substrate itself, or stirs etching liquid, etc. Can be mentioned.

Examples and comparative examples of the present invention will be described below, and the present invention will be described in more detail. However, the present invention is not limited to these examples, and various modifications can be made without departing from the spirit of the present invention. Do.

Example

(Composition of etching liquid)

Table 1 shows the compositions of the etchant of the examples and comparative examples of the present invention.

Table 1

Example number Oxalic acid Alkaline compounds Polysulfonic acid compounds water Example 1 3.4 wt% TMAH 1.5% by weight - Balance Example 2 3.4 wt% TMAH 2.0% by weight - Balance Example 3 3.4 wt% TMAH 2.7 wt% - Balance Example 4 3.4 wt% TMAH 3.8 wt% - Balance Example 5 0.5 wt% TMAH 0.4 wt% - Balance Example 6 1.0 wt% TMAH 0.7 wt% - Balance Example 7 5.0 wt% TMAH 3.2% by weight - Balance Example 8 3.4 wt% Choline 2.6% by weight - Balance Example 9 3.4 wt% MEA 1.4 wt% - Balance Example 10 3.4 wt% 0.8% by weight of hydroxylamine - Balance Example 11 3.4 wt% Sodium hydroxide 0.7% by weight - Balance Example 12 3.4 wt% TMAH 2.4% by weight Demol N 1.0% by weight Balance Example 13 3.4 wt% TMAH 3.0 wt% Demol N 1.0% by weight Balance Comparative Example 1 3.4 wt% - - Balance Comparative Example 2 0.5 wt% - - Balance Comparative Example 3 1.0 wt% - - Balance Comparative Example 4 5.0 wt% - - Balance Comparative Example 5 3.4 wt% - Demol N 1.0% by weight Balance

TMAH: tetramethylammonium hydroxide

MEA: Monoethanolamine

Demol N: sodium salt of naphthalene sulfonic acid formaldehyde condensate (manufactured by Huawang Co., Ltd.)

(Solubility Evaluation of Indium)

Indium oxide powder (average particle diameter: 1 micrometer, purity 99.99%) was added so that each etching liquid shown in Table 1 may be made into 50 degreeC, and it stirred for 2-3 hours. After visually confirming that the indium oxide powder was sufficiently dissolved, each etching solution was filtered through a 0.2 μm filter, the filtrate was sealed in a container, and left in a thermostat set at 37 ° C. Confirmed. In addition, pH of each etching liquid was measured. The amount of indium dissolved in the etching solution was calculated from the weight of added indium, the capacity of the etching solution, and the filter weight change amount before and after filtration. The results are shown in Table 2.

Table 2

Example number pH Indium Dissolution Rate Liquid stability Example 1 1.3 2,000 ppm ○ Example 2 1.5 3,000 ppm ○ Example 3 1.8 5,000 ppm ○ Example 4 3.0 5,000 ppm ○ Example 5 2.0 1,000 ppm ○ Example 6 1.8 1,000 ppm ○ Example 7 1.5 2,000 ppm ○ Example 8 1.5 2,000 ppm ○ Example 9 1.5 2,000 ppm ○ Example 10 1.5 1,000 ppm ○ Example 11 1.3 1,000 ppm ○ Example 12 1.5 3,000 ppm ○ Example 13 1.8 5,000 ppm ○ Comparative Example 1 1.0 1,000 ppm × Comparative Example 2 1.5 1,000 ppm × Comparative Example 3 1.3 1,000 ppm × Comparative Example 4 0.8 1,000 ppm × Comparative Example 5 0.9 1,000 ppm ×

※ Evaluation standard of indium solubility

O: No crystal precipitation over 168 hours (7 days).

X: Precipitate crystal within 24 hours (1 day).

As shown in Table 2, in the etching liquid which does not contain the alkaline compounds like Comparative Examples 1-5, indium melt amount was small and crystal precipitation was recognized within 24 hours. On the other hand, in the etching liquid containing the alkaline compounds of Examples 1-13 of this invention, indium melt | dissolution amount was large and crystal precipitation did not occur over 168 hours (7 days) or more, and liquid safety was extremely excellent. From these results, it can be seen that increasing the indium dissolution amount is effective in suppressing crystal precipitation of indium oxalate, and the etching liquid composition of the present invention has a very excellent effect of suppressing crystal precipitation of indium oxalate. In the etching liquid composition of this invention, the balance of the said indium dissolution amount and liquid stability, and the etching rate mentioned later is especially important.

In addition, as in Comparative Examples 2 and 3, the oxalic acid concentration was lowered, and crystal precipitation was recognized even in a composition having a pH of 1.3 to 1.5. Therefore, simply raising the pH of the oxalic acid-containing etching solution is ineffective and alkaline. It can be seen that the inclusion of the compound is very effective for suppressing the precipitation of crystals of indium oxalate.

(Evaluation of Etching Speed)

Each etching solution shown in Table 1 was heated to 40 ° C, the substrate having a resist pattern formed on an amorphous ITO film having a film thickness of 800 kPa was immersed in each etching solution for 1 minute, washed with water, dried, and then the resist was peeled off. The etching rate was measured by the erosion film thickness meter, and the etching rate was calculated. The results are shown in Table 3.

Table 3

Example number pH Etching Speed (Å / min) Example 1 1.3 620 Example 2 1.5 600 Example 3 1.8 580 Example 4 3.0 440 Example 5 2.0 500 Example 6 1.8 560 Example 7 1.5 590 Example 8 1.5 600 Example 9 1.5 570 Example 10 1.5 570 Example 11 1.3 570 Example 12 1.5 600 Example 13 1.8 580 Comparative Example 1 1.0 640 Comparative Example 2 1.5 530 Comparative Example 3 1.3 590 Comparative Example 4 0.8 640 Comparative Example 5 0.9 640

As shown in Table 3, although the etching liquid containing the alkaline compound of Examples 1-13 of this invention is slightly small compared with the etching liquid which does not contain the alkaline compound of Comparative Examples 1-5, although etching rate is slightly small, it is amorphous. It turns out that it has practically enough etching rate with respect to an ITO film | membrane.

(Residue removal evaluation)

An electron microscope observation was conducted to evaluate the residue after the etching of the substrate on which the ITO film was formed on the glass substrate at a time 1.4 times the appropriate etching time calculated from the etching rate. In addition, an electron microscope observation was performed to etch a substrate on which a silicon nitride (SiN) film was formed on a glass substrate and an ITO film was etched at a time 1.4 times the appropriate etching time calculated at the same etching rate. Later residues were evaluated. The results are shown in Table 4.

Table 4

Example number Residue removal Glass substrate SiN film Example 12 ○ ○ Example 13 ○ ○ Comparative Example 1 × × Comparative Example 5 ○ ○

※ Evaluation standard of residue removal

(Circle): The residue is not recognized at all.

X: The residue is recognized on the entire surface.

As shown in Table 4, in the etching liquid containing only the oxalic acid of Comparative Example 1, the oxalic acid, the alkaline compound and the polysulfonic acid compound of Examples 12 and 13 with respect to the residue recognized on the entire surface together with the glass substrate phase and the SiN film phase. It can be seen that in the etchant containing, it has the same residue removal ability as the etchant containing the oxalic acid and the polysulfonic acid of Comparative Example 5.

The results of Tables 1 to 4 show that the etching solution composition of the present invention has a very good indium dissolution amount and a markedly high liquid stability after dissolving indium, and thus has an excellent effect of inhibiting crystal precipitation of indium oxalate. .

Moreover, it turns out that it has a practically sufficient etching rate equivalent to the etching liquid containing the conventional oxalic acid which does not contain an alkaline compound as a main component.

In addition, it is understood that excellent residue removal ability can be provided by adding a polysulfonic acid compound or the like, as in the etching solution containing a conventional oxalic acid containing no alkaline compound as a main component.

According to the present invention, crystal etching of indium oxalate is effectively performed in an etching apparatus by etching a transparent conductive film such as ITO and IZO formed on a substrate such as glass using an etching solution composition containing oxalic acid and an alkaline compound. It is possible to suppress, the liquid life of the etching solution is greatly extended, thereby reducing the crystal removal work in the apparatus, the frequency of replacement of the filter, and the like, thereby improving the yield and reducing the production cost. Therefore, it is especially useful in the manufacturing technology fields, such as a liquid crystal display and an electroluminescent display, in which transparent conductive films, such as an ITO film and an IZO film, are used.

Claims (7)

The etching liquid composition for transparent conductive films containing oxalic acid and the alkaline compound except triethanolamine. The etching liquid composition according to claim 1, wherein the alkaline compound is one or two or more selected from the group consisting of quaternary ammonium hydroxides, hydroxides of alkali metals, alkanolamines and hydroxylamines except triethanolamine. . The said etching liquid composition for transparent conductive films of Claim 1 or 2 whose pH is 1.1-5.0. The above-mentioned according to claim 1 or 2, further comprising one or two or more compounds selected from the group consisting of polysulfonic acid compounds, polyoxyethylene-polyoxypropylene block copolymers and sulfonate type anionic surfactants. The etching liquid composition for transparent conductive films. The said etching liquid composition for transparent conductive films of Claim 1 or 2 which further contains 1 type (s) or 2 or more types of water-soluble polymers. It is used for the etching of the transparent conductive film containing indium oxide, The said etching liquid composition for transparent conductive films of Claim 1 or 2 characterized by the above-mentioned. The etching method of the transparent conductive film using the etching liquid composition for transparent conductive films of any one of Claims 1-6.