JP2002299326A - Transparent conductive film etching liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an etching liquid for etching a transparent conductive film containing indium oxide. SOLUTION: The etching liquid for etching a transparent conductive film contains halogen acid and a metal halide, and the liquid further contains an oxidizer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an etching solution for a transparent conductive film containing indium oxide used for a liquid crystal display (LED) and the like.

[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 reflective films, photoelectric conversion elements and transparent electrodes of various flat panel displays. Have been. Recently, with the spread of notebook PCs, small TVs, portable information terminals, and the like, demand for liquid crystal displays (LCDs) is increasing.

[0003] In the field of flat panel display, a transparent conductive film such as ITO is used as a display electrode of a pixel and is formed by etching by photolithography. Such a transparent conductive film has an oxidizing effect on the metal layer, and a fine electrode pattern can be formed with high accuracy by using an etching solution composed of an acidic aqueous solution containing halogen ions.

Japanese Patent Application Laid-Open No. 5-62966 proposes a method using a saturated aqueous solution of oxalic acid. In this method, since the etching rate of the crystalline transparent electrode is low, the method is limited to an amorphous transparent electrode film.

Japanese Patent Application Laid-Open No. Hei 10-91084 proposes a method in which an etching treatment is performed using an acid solution containing halogen ions such as hydrochloric acid and an oxidizing agent, and then sludge is removed using a solution of a halogen alkali metal salt. In this method, the etching rate is low because the first-step processing in which etching is performed at a low etching rate and the second-step processing using a halogen alkali metal salt solution that is not related to the etching rate.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the prior art and to provide an etching solution capable of obtaining a high etching rate for a crystalline transparent electrode film by a one-step process.

[0007]

The present inventors have made intensive studies on the patterning of a transparent conductive film containing indium oxide on a glass substrate or a plastic substrate. Further, the present inventors have found that a large etching rate can be obtained by one-step processing using an etching solution containing an oxidizing agent, and that corrosion of device materials can be prevented. That is, the present invention relates to an etching solution for a transparent conductive film which is an aqueous solution containing a halogen acid and a halogen metal salt, and further relates to an etching solution for a transparent conductive film which is an aqueous solution containing an oxidizing agent.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A transparent conductive film, which is an object of the present invention, is formed on a glass substrate or a plastic substrate by a method such as a sputtering method, an ion plating method, and a vapor deposition method.
A film formed with a thickness of 0 to 5000 ° is exemplified.
Further, a case where the light transmittance is 70% or more and the specific resistance is 1 Ωcm or less is also exemplified. Other oxides such as tin oxide and zinc oxide may be added to the thin film. The etching solution of the present invention is particularly advantageous for a crystal-type transparent electrode.

The halogen acids used in the present invention include hydrofluoric acid, hydrochloric acid, hydrogen bromide and hydrogen iodide. Examples of the halogen metal salts include halides of fluoride, chloride, bromide and iodide of alkali metals such as sodium and potassium, halogen salts of alkaline earth metals such as calcium and magnesium, and halogen salts of aluminum. In particular, since alkaline earth metals have high solubility in halogen acids, it is preferable that the concentration can be increased so that the etching rate can be improved. Two or more of these halogen metal salts can be used. The halogen acid and halogen metal salt are diluted with water or an organic solvent such as alcohols.

The oxidizing agent is used to increase the etching rate and to greatly reduce the corrosion of the device material by the halogen acid or the halogen metal salt. Specifically, nitrates, nitrites, hydrogen peroxide, organic peroxides and the like of alkali metals and alkaline earth metals, such as calcium chlorate,
Examples include sodium nitrate, calcium nitrate, acetic peroxide, and hydrogen peroxide.

[0011] The concentration of each component is 0.1 to 6 halogen acid.
mol / L, preferably 1 to 5 mol / L, and the halogen metal salt is 0.01 to 6 mol / L, preferably 0.1
-5 mol / L, and the oxidizing agent is 0.01-2 mol / L.
L. Furthermore, in order to obtain a preferable etching rate, the halogen concentration in the etching solution is 1 mol / L or more.
It is a saturated concentration, and the halogen content of the halogen metal salt is 10 to 90% by weight of the total halogen content in the etching solution.
It is.

The etching temperature is a temperature at which a predetermined etching rate can be obtained, and is generally 30 to 70 ° C. The etching method is performed by a ripping method or a spray method, but is not particularly limited. In addition, by etching while blowing a gaseous oxidizing agent such as oxygen, chlorine, nitrogen oxide, or ozone, corrosion of the device material can be reduced and the life of the device can be extended.

The method of using the etchant is as follows. 1. A photosensitive material is applied on the thin film. 2. The photosensitive material is irradiated with an electromagnetic wave or an electron beam through a photomask on which a pattern is drawn. 3. The photosensitive material is developed to obtain a resist pattern. 4. The portion of the thin film that is not protected by the resist is etched and removed with the etching solution of the present invention.

[0014]

EXAMPLES The present invention will be specifically described by way of examples.
The concentration is Mol / L.

Examples 1 to 18 and Comparative Examples 1 to 12 (1) Film formation A thin film of indium oxide (95%) + tin oxide (5%) having a thickness of 1500.degree. A thin film was formed on a substrate (0.25 mm thick) by a sputtering method. (2) Film properties The thin film thus formed had the light transmittance and specific resistance shown in Table 1.

[0016]

[Table 1]

(3) Formation of resist pattern A resist solution was applied on the thin film surface of the substrate shown in Table 1 with a roll coater and prebaked with hot air at 100 ° C. for 15 minutes. The thickness of the resist after prebaking was 2 μm. Thereafter, through a photomask on which a pattern is drawn, a wavelength of 35
The resist was irradiated and exposed to a light beam of 0 to 450 nm. Then, immersing and developing while applying vibration to the developer at 25 ° C., peeling off the unexposed portion of the resist with a peeling agent, and washing with water,
Dry at 100 ° C. for 30 minutes.

(4) Etching solution The chemical compositions of the aqueous solution for the one-stage treatment of the present invention used for etching the thin film surface of the resist-patterned substrate are shown in Table 2 by the chemical numbers 1 to 8. Drugs used for the comparative example in the one-stage process are shown as drug numbers 9 to 12, and drugs used in the two-stage process are shown as number 13.

[0019]

[Table 2]

(5) Etching A chemical was sprayed on the thin film surface of the resist-patterned substrate and etched under the conditions shown in Table 3. The etching time was defined as the time during which the surface resistance after etching became infinite with a tester.

[0021]

[Table 3]

(6) Corrosion resistance of metallic material of equipment Round bar of Ti alloy material (diameter 10 mm × length 5
mm) was immersed in a drug at 25 ° C. for 7 days, and the corrosiveness of the drug was confirmed from the weight loss of the round bar. Table 4 shows the results.

[0023]

[Table 4]

[0024]

According to the present invention, the etching rate is improved by the etching solution of the present invention, and good patterning can be obtained. Then, the halogen acid concentration can be reduced, the contamination of the working environment of the halogen acid can be reduced, and the etching can be performed without corroding the device material.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tadashi Okazaki 6-1-1-1 Shinjuku, Katsushika-ku, Tokyo Inside the Tokyo Research Laboratory Mitsubishi Gas Chemical Co., Ltd. (72) Inventor Yoshiaki Inoue 6-1-1 Shinjuku, Katsushika-ku, Tokyo No. 1 In the Tokyo Laboratory, Mitsubishi Gas Chemical Co., Ltd. (72) Inventor Joji Kiuchi 5-428, Hanakoganei, Kodaira-shi, Tokyo F-term in Nihon Fluorine Industry Co., Ltd. 2K009 CC03 DD12 EE03 5F043 AA26 BB18 GG04

Claims (3)

[Claims] An etching solution for a transparent conductive film containing a halogen acid and a halogen metal salt. 2. The etching solution for a transparent conductive film according to claim 1, further comprising an oxidizing agent. 3. A method for etching a transparent conductive film, wherein etching is performed while blowing a gaseous oxidant into the etching solution according to claim 1.