JPS6243012A - Etching of transparent conducting film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for etching transparent conductive films used in display devices such as liquid crystal displays.

2. Description of the Related Art Transparent conductive films are used in display devices such as liquid crystal displays and electrochromic displays. Thin film materials containing indium oxide as a main component have low resistivity, high light transmittance, and are easily etched, making them the most suitable transparent electrode materials for display devices. Usually, the transparent conductive film is patterned into stripes or the like. A common patterning method is to form a photoresist into a predetermined pattern and then etch the indium oxide film using a mixture of hydrochloric acid, ferric chloride, and water.

Problems to be Solved by the Invention In the conventional method, when etching indium oxide, the etching solution penetrates into the interface between the photoresist and the indium oxide film, resulting in etching into a shape smaller than the photoresist pattern.

The present invention has been made in view of this point, and an object of the present invention is to provide a method for etching an indium oxide film into the same shape as a photoresist.

Means for solving the problem: A solution containing hydrobromic acid as a main component is used as an etching solution for the indium oxide film.

Etching solution mainly composed of hydrobromic acid can etch the indium oxide film without seeping into the interface between the photoresist layer and indium oxide, so the pattern of the indium oxide film is the same as the photoresist pattern. can.

EXAMPLE A negative resist was applied using a spinner onto an indium oxide film to which tin oxide was added, which was formed on a glass substrate. The thickness of the indium oxide film is 150 nm.

The film thickness of the photoresist is 1.2 μm. 1 at 90℃
After prebaking for 0 minutes, it was exposed to ultraviolet light using a photomask. After development, post-baking was performed at 130° C. for 30 minutes. Etching was performed in 47% hydrobromic acid at room temperature for 4 minutes.

The minimum pattern width is 20 μm. The cross section of the pattern after washing with water was observed using a scanning electron microscope (SKM). The results are schematically shown in FIG. The indium oxide film 2 on the glass substrate 1 is patterned in the same shape as the photoresist film 3. For comparison, FIG. 2 shows the results of etching at 40° C. for 6 minutes using a mixture of hydrochloric acid, ferric chloride, and water. The indium oxide film 12 on the glass substrate 11 was thinner than the photoresist pattern because the etching solution penetrated into the interface with the photoresist 13. Furthermore, the reproducibility of pattern width is also poor.

Note that when a positive type photoresist was used, the same results as with a negative type photoresist were obtained.

Effects of the Invention According to the present invention, a pattern of an indium oxide film can be formed with high precision through an extremely simple process, and is extremely useful in practice.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a cross section of a transparent electrode obtained by the etching method of the present invention, and Fig. 2 is a schematic diagram showing a cross section of a transparent electrode obtained by a conventional etching method.
Indium oxide film, 3,13...photoresist film.

Claims (1)

[Claims] A photoresist is formed in a predetermined pattern on a transparent conductive film mainly composed of indium oxide formed on a substrate,
A method for etching a transparent conductive film, which is characterized by etching using this photoresist as a mask and using hydrobromic acid as an etchant.