JPS6255896A - Pattern formation 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 Industrial Application The present invention relates to a method for forming a pattern of a transparent conductive film containing indium oxide as a main component used in devices such as thin film KL elements and image pickup tubes.

Conventional technology A transparent conductive film containing indium oxide as its main component is generally formed by forming a photoresist into a predetermined pattern, and then using this as a mask for etching with a mixture of hydrochloric acid and ferric chloride. Ta.

Problems to be Solved by the Invention In thin film devices such as thin film IEL elements and image pickup tubes, it is necessary to form a taper at the edge of the transparent electrode pattern to prevent dielectric breakdown of the thin film layer formed thereon. However, when a mixture of hydrochloric acid and ferric chloride is used, there is a problem in that it is not possible to simultaneously form a sufficiently gentle taper at the edge of the pattern and accurately determine the pattern size.

In order to form a gentle taper at the edge of the pattern, the adhesion between the photoresist and the transparent conductive film is adjusted so that an etchant consisting of a mixture of hydrochloric acid and ferric chloride is soaked into the interface between the two. By doing this, the transparent conductive film is etched while the etchant permeates, so that a taper is formed at the edge of the pattern.

However, in order to prevent etching residue, it is necessary to take an extra long etching time. Furthermore, since the etchant penetrates into the interface between the 7-photoresist and the transparent conductive film, the pattern size becomes smaller. In extreme cases, the photoresist peels off during etching. If you try to get the pattern size accurately and prevent the etchant from soaking in, you will not be able to form tabers at the pattern edges. In this way, it has not been possible to form the taper smoothly and to accurately determine the pattern size at the same time.

Means to solve problems Pattern formation of a transparent conductive film is performed through the following steps.

(IL) A step of forming a photoresist film in a predetermined pattern on the transparent conductive film. (b) Etching the ITO transparent conductive film with hydroiodic acid or hydrobromic acid. (C)
A step of forming a taber on the edge of the ITO transparent conductive film pattern using an etching solution containing hydrochloric acid.

Function: After forming a predetermined photoresist pattern using a conventional method, a transparent conductive film pattern having the same dimensions as the photoresist pattern is formed by etching with hydroiodic acid or hydrobromic acid. When the transparent conductive film is etched using an etchant, a transparent conductive film pattern having a gentle taper at the edge portions is formed.

Example An embodiment of the present invention will be described below.

In this method, etching is performed in two stages using two types of etching solutions with different properties.

In the first step, the transparent conductive film containing indium oxide as a main component is etched using hydroiodic acid or hydrobromic acid according to a pattern defined by the photoresist pattern. Since these etchants do not penetrate between the resist and the transparent conductive film, the pattern size does not become narrower even if the etching time is made extra long. On the other hand, almost no tapering is formed at the edge portions of the transparent electrode pattern. In the second step, an etchant containing hydrochloric acid forms a gentle taper at the edge of the pattern.

Since the pattern of the transparent electrode has already been completed, there is no need to take an extra long etching time for forming the taber, so the pattern size does not become smaller.

First Embodiment A concrete first embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, a negative type photoresist film 3 is formed in a predetermined pattern on an ITO transparent conductive film 2 with a film thickness of soon m provided on a glass substrate 1. As shown in FIG.

Post-baking was carried out at 130"C for 30 minutes. The resist used was KMR made by Kodak. Next, etching was performed using hydroiodic acid at 40°C for 10 minutes, resulting in a transparent conductive film as shown in Figure 2. No. 2 was etched with good pattern accuracy without leaving any etching residue.Next, etching No. 4 was performed using an etchant containing a mixture of hydrochloric acid and ferric chloride in a ratio of 1=2.
After etching at 0°C for 3 minutes, the etching solution penetrates from the edges of the resist pattern as shown in Figure 3.
When the resist film 3 is removed after etching, a striped transparent conductive film 2 having a gentle taper at its edges is formed as shown in FIG.

The penetration depth (tabular width) changes depending on the etching temperature and etching time, and is approximately 4 μm at 40'C for 3 minutes.
It is.

Second Example In this example, a positive type photoresist, Microposit 1400 manufactured by Shipley Co., Ltd., was applied on a transparent conductive film.
-31 to form a predetermined pattern. No post-bake is performed. Thereafter, as in the first embodiment, etching was performed for 10 minutes with hydrobromic acid at 35°C, and then etching was performed at 36°C for 2 minutes with a 1:1 mixture of hydrochloric acid, nitric acid, and water. When the resist is removed, a transparent conductive film with a gentle taper is formed at the edges. The reason why post-baking is not performed is that baking prevents the etching solution from penetrating into the positive type resist.

As mentioned in these examples, an etching solution containing hydrochloric acid is preferred because it has the property of easily penetrating into the interface between the photoresist and the transparent conductive film containing indium oxide as a main component, and the property of etching the transparent conductive film. It is.

Effects of the Invention According to the present invention, it is possible to provide a simple and highly reproducible pattern forming method for a transparent conductive film mainly composed of indium oxide, which has an accurate pattern size and a gentle taper at the edge of the pattern. .

[Brief explanation of drawings]

1 to 4 are cross-sectional views showing steps in an embodiment of the method for forming a pattern of a transparent conductive film according to the present invention. 1...Glass substrate, 2-...Transparent conductive film, 3...Photoresist film. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] After forming a photoresist film in a predetermined pattern on a transparent conductive film containing indium oxide as a main component, and etching the transparent conductive film with an etching solution containing at least one of hydroiodic acid and hydrobromic acid, 1. A method for forming a pattern of a transparent conductive film, comprising the step of etching with an etching solution containing hydrochloric acid.