JP2002033304A - Composition for etching - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an etchant, by which no etching residue is generated and etching is conducted under mild conditions, when wet etching a transparent conductive film. SOLUTION: The composition for etching is composed of an aqueous solution, containing oxalic acid, aminocarboxylic acid and/or salts of aminocarboxylic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an etching composition.

[0002]

2. Description of the Related Art Transparent conductive films such as ITO (indium-tin oxide) films are widely used in the field of electronic devices such as antistatic films, heat reflection films, photoelectric conversion elements and transparent electrodes of various flat panel displays. I have been. In particular,
Recently, with the spread of notebook PCs, small TVs, portable information terminals, and the like, demand for liquid crystal displays (LCDs) is increasing. A transparent conductive film such as ITO is used as a display electrode of a pixel in the field of a flat panel display, and is formed by etching of photolithography. However, liquid crystal displays (LC
D) In particular, in the field of TFT-LCD, polycrystalline ITO has conventionally been used, but as the substrate size increases, it becomes more difficult to make the polycrystalline ITO uniform.
In addition, as a method for forming the display electrode, a photoresist is coated on a transparent conductive film, exposed and developed, and then, using an etching agent with the photoresist as a mask, the remaining photoresist is removed after etching. Formed. Conventionally, ferric chloride / hydrochloric acid aqueous solution, iodic acid aqueous solution, phosphoric acid aqueous solution, hydrochloric acid / nitric acid aqueous solution (aqua regia) and the like have been used as an etching agent for the transparent conductive film such as the polycrystalline ITO. The wet etching agent for the transparent conductive film or the like corrodes to Al or the like during patterning, and selective etching proceeds from the grain boundaries, so that it is difficult to perform patterning with high processing accuracy. For the above reasons, with the enlargement of the substrate size, the enlargement of the TFT panel, the high definition, the Al wiring, etc., the demand for an etching agent capable of etching with high processing accuracy as a pixel display electrode is increasing. . In order to solve these problems, a method of using amorphous ITO and wet-etching the amorphous ITO with a weak acid, particularly an oxalic acid aqueous solution, has recently been proposed. However, when wet etching is performed on amorphous ITO using an oxalic acid aqueous solution, there is a problem that an etching residue is generated, and an etchant that does not generate the etching residue is desired.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of forming a transparent conductive film or the like, as described above, in which no etching residue is generated at the time of wet etching using an oxalic acid aqueous solution. It is an object of the present invention to provide a wet etching agent capable of performing etching under a suitable condition.

[0004]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, the aqueous solution containing oxalic acid and an aminocarboxylic acid and / or a salt of an aminocarboxylic acid was found to be transparent. It has been found that etching of a conductive film or the like can be performed under mild conditions and that no residue is generated, and the present invention has been completed.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The concentration of oxalic acid used in the present invention is 0.01 to 10
% Is preferred, the etching rate is lower than 0.01% by weight, and the etching rate is lower than 10% by weight.

Specific examples of the aminocarboxylic acid and its salt include those described below, but are not particularly limited thereto. (1) Examples of aminocarboxylic acids having one carboxyl group and salts thereof include aminoacetic acid, dihydroxyethylglycine, and the like, and salts thereof.

(2) Examples of aminocarboxylic acids having two carboxyl groups and salts thereof include imino diacetic acid, hydroxyethyl imino diacetic acid, ethylene diamine diacetic acid, ethylene diamine dipropionic acid, and the like, and salts thereof.

(3) Examples of aminocarboxylic acids having three carboxyl groups and salts thereof include nitrilotriacetic acid, hydroxyethylethylenediaminetriacetic acid, nitrilotripropionic acid, and salts thereof.

(4) Aminocarboxylic acids having four carboxyl groups and salts thereof include ethylenediaminetetraacetic acid, trans-1,2-cyclohexanediamine-N,
N, N ', N'-tetraacetic acid, diaminopropanol 4
Examples include acetic acid, glycol ether diamine tetraacetic acid, hexamethylene diamine-N, N, N ', N'-tetraacetic acid, diaminopropane tetraacetic acid, and the like, and salts thereof.

(5) Examples of the aminocarboxylic acid having five carboxyl groups and salts thereof include diethylenetriaminepentaacetic acid and the like, and salts thereof.

(6) Examples of aminocarboxylic acids having six or more carboxyl groups and salts thereof include triethylenetetramine hexaacetic acid and the like, and salts thereof.

(7) Other similar compounds include amine compounds capable of forming a complex such as triethanolamine and salts thereof.

The above-mentioned aminocarboxylic acids and salts thereof may be used alone or in combination of two or more. The preferred concentration is 0.0001 to 5% by weight. The aminocarboxylic acid and its salt preferably include those having four or less carboxyl groups. If the concentration of the aminocarboxylic acid and the salt thereof is 0.0001% by weight or less, a residue is generated at the time of etching. If the concentration is 5% by weight or more, the etching rate of ITO is reduced or the ITO is not sufficiently dissolved. It is not desirable.

The etching composition of the present invention is used in accordance with a conventional method. The use temperature is from room temperature to 90 ° C., and the use time is about 0.1 to 30 minutes. In addition, the present invention provides a transparent conductive thin film such as IZO (indium-zinc oxide) and various semiconductors in addition to amorphous ITO.
It is also suitably used for wet etching.

[0015]

EXAMPLE 1 The substrate shown in FIG. 1 was obtained by forming an insulating film of SiN2 on a glass substrate 1, and further forming an amorphous ITO3 on the glass substrate 1.
This is a state after a resist has been applied on the amorphous ITO and developed. Using the substrate shown in FIG. 1, a cleaning solution, which is an aqueous solution containing 3.4% by weight of oxalic acid and 0.2% by weight of dihydroxyethylglycine, is used.
After etching and washing with water at 2 ° C. for 2 minutes, the resist 4 was further stripped with a basic resist stripper, washed with water, and the surface was observed with a dried SEM (electron microscope). No residue was observed.

COMPARATIVE EXAMPLE 1 The substrate used in Example 1 was etched at 40 ° C. for 2 minutes with a cleaning solution that was an aqueous solution containing 3.4% by weight of oxalic acid, and then dried. Further, after the resist 4 was stripped off with a basic resist stripping solution, the resist was washed with water, and as a result of SEM observation, the amorphous ITO 3 was etched, but a large number of residues 5 were observed as shown in FIG.

Comparative Example 2 The substrate used in Example 1 was etched at 40 ° C. for 2 minutes using a cleaning agent which was an aqueous solution containing 0.2% by weight of dihydroxyethylglycine. After the resist was stripped with a resist stripper, it was washed with water and dried. As a result of SEM observation, the amorphous ITO was hardly etched.

Example 2 The substrate used in Example 1 was etched at 40 ° C. for 2 minutes using a cleaning solution which was an aqueous solution containing 3.4% by weight of oxalic acid and 0.2% by weight of iminodiacetic acid. , After washing with water,
Further, the resist was stripped with a basic resist stripping solution, washed with water and dried. As a result of the SEM observation, the amorphous ITO was favorably etched, and no residue was observed.

Example 3 The substrate used in Example 1 was etched at 40 ° C. for 2 minutes using a cleaning solution which was an aqueous solution containing 3.4% by weight of oxalic acid and 0.2% by weight of hydroxyethyliminodiacetic acid. After washing with water, the resist was stripped with a basic resist stripping solution, washed with water, and dried. As a result of SEM observation,
The amorphous ITO was etched well and no residue was observed.

Example 4 The substrate used in Example 1 was etched at 40 ° C. for 2 minutes using a cleaning solution which was an aqueous solution containing 3.4% by weight of oxalic acid and 0.2% by weight of nitrilotriacetic acid. , After washing, after further stripping the resist with a basic resist stripper,
Washed with water and dried. As a result of the SEM observation, the amorphous ITO was favorably etched, and no residue was observed.

Example 5 The substrate used in Example 1 was etched at 40 ° C. for 2 minutes using a cleaning solution that was an aqueous solution containing 3.4% by weight of oxalic acid and 0.2% by weight of ethylenediaminetetraacetic acid. After washing with water, the resist was stripped with a basic resist stripping solution, washed with water, and dried. As a result of the SEM observation, the amorphous ITO was favorably etched, and no residue was observed.

Example 6 The substrate used in Example 1 was etched at 40 ° C. for 2 minutes using a cleaning solution which was an aqueous solution containing 3.4% by weight of oxalic acid and 0.2% by weight of triethanolamine. ,
After washing with water, the resist was further stripped with a basic resist stripping solution, washed with water, and dried. As a result of SEM observation, amorphous IT
O was etched well and no residue was observed.

Example 7 Using a cleaning solution which is an aqueous solution containing 3.4% by weight of oxalic acid and 2.0% by weight of dihydroxyethylglycine,
The substrate used in Example 1 was etched at 40 ° C. for 2 minutes, washed with water, and further, the resist was stripped off with a basic resist stripping solution, washed with water and dried. As a result of the SEM observation, the amorphous ITO was favorably etched, and no residue was observed.

Example 8 The substrate used in Example 1 was etched at 40 ° C. for 2 minutes using a cleaning solution that was an aqueous solution containing 1.0% by weight of oxalic acid and 0.2% by weight of dihydroxyethylglycine. After washing with water, the resist was further stripped with a basic resist stripping solution, washed with water, and dried. As a result of the SEM observation, the amorphous ITO was favorably etched, and no residue was observed.

Example 9 The substrate used in Example 1 was etched at 40 ° C. for 2 minutes using a cleaning solution which was an aqueous solution containing 5.5% by weight of oxalic acid and 0.2% by weight of dihydroxyethylglycine. After washing with water, the resist was further stripped with a basic resist stripping solution, washed with water, and dried. As a result of the SEM observation, the amorphous ITO was favorably etched, and no residue was observed.

Comparative Example 3 The substrate used in Example 1 was etched at 40 ° C. for 2 minutes using a cleaning solution which was an aqueous solution containing 5.5% by weight of acetic acid and 0.2% by weight of dihydroxyethylglycine.
After washing with water, the resist was further stripped with a basic resist stripping solution, washed with water, and dried. As a result of SEM observation, amorphous IT
O was hardly etched.

[0027]

When the etching composition of the present invention is used, the transparent conductive film can be etched under mild conditions, and no residue is generated.

[Brief description of the drawings]

FIG. 1 is a state diagram after a film of SiN as an insulating film is formed on a glass substrate, a film of amorphous ITO is formed, a resist is applied on the film of amorphous ITO, and development is performed. is there.

FIG. 2 is a diagram showing a state in which a resist is removed after etching the substrate of FIG. 1 with a conventional etching solution.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 glass substrate 2 SiN 3 amorphous ITO 4 resist 5 residue

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Tetsuo Aoyama 182 Tayuhama Niigata, Niigata City, Niigata Prefecture F-term in Niigata Research Laboratory, Mitsubishi Gas Chemical Co., Ltd. 5F033 HH38 QQ20 5F043 AA26 BB18 GG02 GG04

Claims (4)

[Claims] An etching composition comprising an aqueous solution containing oxalic acid and an aminocarboxylic acid and / or a salt of an aminocarboxylic acid. 2. The etching composition according to claim 1, wherein the number of carboxyl groups of the aminocarboxylic acid is 4 or less. 3. The etching composition according to claim 1, which is a composition for wet etching a transparent conductive film. 4. The etching composition according to claim 3, wherein the transparent conductive film is an indium-tin oxide film.