JPH0219483A - Formation of electrically conductive film pattern - Google Patents

Abstract

PURPOSE:To form a fine pattern having high linearity and no indent at the line edges by masking an electrically conductive film on the surface of a polymer film with a photosensitive resist, exposing and developing the resist and adhering the electrically conductive film to the developed resist. CONSTITUTION:An electrically conductive transparent film of tin oxide and/or indium oxide is formed on the surface of a polymer film and masked with a photosensitive resist. This resist is exposed through a prescribed pattern and developed. The polymer film is then held at a constant temp. and humidity to tightly adhere the electrically conductive film to the developed resist and etching is carried out to form a fine pattern having high linearity and no indent at the line edges.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for forming a pattern on a conductive film,
More specifically, the present invention relates to a dot matrix etching formation method particularly suitable for forming ultra-fine patterns of conductor or semiconductor films made of metal or metal oxide applied by vapor deposition or the like on a polymer film as a substrate.

The conductive polymer film, which has a conductive thin film on the polymer film, can be used for wiring boards, heaters, touch panel electrodes,
Orui can be considered for use in electrodes for liquid crystal displays, etc.
Generally, in order to use it for such purposes, it is necessary to leave the necessary parts of the conductive film applied over a wide area, usually the entire surface, and to dissolve and remove the other parts, that is, to etch it into a predetermined pattern. becomes.

Recently, there has been active development of liquid crystal display elements using conductive polymer films as electrodes, but especially in the case of dot matrix display types, the electrode patterns are extremely fine (thin line 3
0 to 50 μm) is becoming increasingly necessary.

(Prior Art) Conventionally, as a method for etching a conductive film formed on a substrate, a mask is first formed in a predetermined pattern on the conductive thin film using a screen printing method or a photoresist method. A method is used in which the patterned mask is etched, and then the patterned mask is dissolved and removed using a release agent.

Comparing conventional pattern forming methods in terms of resolution, workability, etc., for example, in the screen printing method, a masking agent is applied on a conductive film according to the pattern using a predetermined pattern screen plate, and then etched to form a predetermined pattern. However, due to the mesh of the screen plate, the resolution is limited to 300 .mu.m, which is extremely unsuitable for forming extremely fine patterns (30 to 50 .mu.m) such as those used as electrodes for dot matrix displays. There are two types of photoresist methods: coating type and resist film sticking type. In this case, unlike the coating type using a screen plate, there is no fundamental problem regarding resolution, and even fairly thin patterns can be formed. Therefore, the resist-coated S type has traditionally been widely used for Nesa glass, but when the substrate is replaced from glass to a polymer film, the adhesion of the conductive imitation is generally poor, but it is difficult to form accurate fine patterns. is difficult to form. Especially indium
Added to this is the poor adhesion between the semiconductor made of tin oxide and the film resist, making it difficult to form accurate fine patterns.

For these reasons, it has been desired to develop a method for forming fine dot matrix etching patterns (30 to 50 .mu.m) for polymer films.

(Objective of the Invention) The present inventors aim to develop a method for etching a conductive film finely so that it can be used as an electrode for displaying a conductive film without unevenness in the lines.

(Structure of the Invention) That is, the present invention involves masking the conductive film of a polymer film having a conductive film on the surface with a photosensitive resist, exposing it to a predetermined pattern, developing it, and then keeping the film at constant temperature and humidity. This is a pattern forming method for a conductive film that is characterized by etching after placing it in an environment.

The heating and humidification in the method of the present invention may be performed at temperatures above the lowest temperature and above 50%.

In the case of polyethylene terephthalate film, which is a typical substrate, the temperature is 25°C to 40'C and 70% to 95%.
The temperature is preferably around 25°C and 180%. At such temperatures and humidity, the processing time required to achieve the objectives of the invention is approximately 8 hours.

In order to shorten this time, it is better to adjust the humidity rather than the temperature. At 25°C and 195%, it takes about half of that, 4 hours.

According to the present invention, water can be gradually removed and dried from the swollen photosensitive resist after viewing in this step,
As a result, the conductive film and the resist can be firmly adhered to each other. Therefore, after this etching, there are no irregularities or chips in the conductive film in the pattern lines.

Examples of the conductive film of the present invention include metal thin films such as silver, copper, and aluminum, and metal oxide thin films such as tin oxide and indium oxide. These thin films are usually applied by vapor deposition or the like, and their thickness is preferably 1000 Å or less. The vapor deposition methods include vacuum vapor deposition, RF and DC.
Any method such as sputtering or ion blating may be used.

Any type of photosensitive resist may be used. These are usually divided into two types based on the development method: the solvent type, which removes the unexposed areas with a solvent, and the water-soluble type, which removes the unexposed areas with a water-based product, but there is no difference in the photosensitive mechanism. , either type may be used in the present invention. The material may be selected based on the adhesion of the exposed resist portion to the conductive film. For example, in the case of indium oxide and/or tin oxide, which provide a transparent conductive film, a water-soluble type is preferable.

Development may be performed using a development method unique to the resist.

As the etching method, a method of dipping into an etching solution is generally used. However, a spray method in which etching is performed by spraying an etching solution onto the conductive film can also be used for the purpose of accelerating the etching of the dipping method. In the immersion method, a method may also be used in which etching is accelerated by stirring the etching solution at high speed while the conductive film is immersed.

As the etching solution, a known one can be used, or it is appropriately selected depending on the type of the conductive thin film to be etched. For example, in the case of indium tin oxide, a dilute solution of hydrochloric acid or an acidic aqueous solution of ferric chloride is used. The concentration of these etching solutions may be 1% by weight or more, but preferably 2% by weight considering the etching speed and damage to the substrate.
It is preferably between 0% and 50% by weight.

In addition, the polymer film used in the present invention includes polystyrene, polymethyl acrylate, polycarbonate, polyvinyl chloride, acetate-1~, polyether salvon, polysulfone, polyethylene, polypropylene, polyamide, polytetrafluoroethylene, polyester. Examples include plastics such as

(Effects) In the present invention, if heating and humidification are performed after development, it is effective in easily forming a fine dot matrix display electrode pattern of about 30 μm and having good linearity with no unevenness in the line edges.

Hereinafter, the method of the present invention will be explained in detail with reference to Examples.

Example 1 Polyethylene terephthalate film has a surface resistance of 30
An indium-tin oxide thin film was deposited so that the resistance was 0Ω/mouth. This film has a water-soluble treatment type photosensitive film L/Cyst (PH0TEC862-AF manufactured by Hitachi Chemical Co., Ltd.).
-25> is laminated with a microscopic (for display) A nid mask (
30μ, 40μ, 50μ, 60μ, 70μ, 80μ, 1
00μ thin line pattern). After exposure, the non-exposed areas were dissolved and removed with a dilute aqueous alkaline solution.

After leaving the apparatus in an environment of 25° C. and 80% RH at 8 o'clock, it was etched with a 25% by volume hydrochloric acid aqueous solution (25° C.).

After drying, the resist agent was peeled off with a weakly alkaline solution (0.75 wt aqueous ammonia), and the laminated resist agent was removed and etching was completed.
A fine etching pattern with a width of 0 μm to 100 μm was formed as a pattern with very good linearity, with no unevenness at the edge of the line. The display electrode thus formed could be used as a dot matrix. There was no damage to the appearance of the polyethylene terephthalate film.

Comparative Example 1 In the same manner as in Example 1, an indium-tin oxide thin film having a surface resistance of 3000/hole was deposited on a polyethylene terephthalate film.

This was laminated with the same photosensitive film resist and exposed using a fine display photomask.

After dissolving and removing the non-exposed areas with a dilute alkaline aqueous solution,
It was immediately etched with a 25% by volume aqueous hydrochloric acid solution (25°C). After drying, the resist agent was removed with an aqueous aqueous solution. As a result, etching patterns with a width of 100 to 80 μm were formed, but when etching patterns with a width of 70 to 40 μm were found, there were many irregularities in the line edges in some places, and the line width also deviated by about ±10 μm from the design value. Ta.

Therefore, it was found that the limit of this method is about 80 μm.

Claims (1)

[Claims] 1. The conductive film of a polymer film having a conductive film on its surface is masked with a photosensitive resist, exposed to light in a predetermined pattern, developed, and then the film is placed in a constant temperature and humidity environment. A pattern forming method for a conductive film, characterized in that etching is performed after the conductive film and the resist after development are firmly attached to each other. Claims: The conductive film is a transparent film made of tin oxide and/or indium oxide. Method 3 for forming a pattern on a conductive film according to claim 1. Method for forming a pattern on a conductive film according to claims 1 and 2, wherein the photosensitive resist is water-soluble.