JPS61208047A - Formation of conductive film pattern - Google Patents

Abstract

PURPOSE:To obtain a superior fine pattern by masking a conductive film on a polymer film with a photosensitive film resist of an aq. soln.-processing type, and after patternwise exposure and development, bringing it into contact with an aq. acid soln. different from an etchant, and then, etching it with the etchant. CONSTITUTION:The conductive film made of SnO2, In2O3, or ITO on a polymer film is masked with a photosensitive film resist of an aq. soln.-processing type, and after exposure to a prescribed pattern and development, it is preliminarily brought into contact with an aq. acid soln. different from an etchant, same in the kind of acid but comparatively lower in concn. and then, it is processed with the etchant. The pattern obtained by peeling the resist after the etching is free from roughness on the edge, good in linearity, and as fine as about 50mum width, thus permitting this process to be used for forming printed circuits, electrodes of heaters and touch panels, and electrodes of liquid crystal display devices, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for forming a polar pattern of a conductive film. This invention relates to a method for forming ultra-fine etching patterns.

A conductive thin film on a polymer film can be used for wiring boards, heaters, touch panel electrodes, liquid crystal display electrodes, etc., but in general, in order to use it for such purposes, It is necessary to dissolve away a portion of the conductive film, ie, to etch it into a predetermined pattern.

Furthermore, recently, liquid crystal display elements using conductive polymer films as substrates have been actively developed, and as a result, it has become necessary to process the electrode patterns into fine lines (50 to 100 microns).

(Prior art) Conventional methods for etching a conductive thin film formed on a substrate include first forming a mask in a predetermined pattern on the conductive thin film using screen printing or photoresist methods, and then etching. Thereafter, the patterned mask is dissolved and removed using a release agent.

Comparing the resolution, workability, etc. of conventional pattern forming methods, for example, in the screen printing method, a masking agent is applied onto a transparent conductive film using a predetermined pattern forming screen plate, and then etched to form a predetermined pattern. However, due to the size of the screen plate, it is difficult to form fine patterns (50 to 100 μm) used as display electrodes. That is, the limit of this resolution is about 300 μm. There are two types of photoresist methods: coating type and solvent-treated Taigu photosensitive film type. In this case, there is no problem with resolution, and even fairly thin patterns can be formed. Therefore, the resist coating type was often used for conventional Nesa glass substrate electrodes, but by replacing the substrate with a transparent conductive polymer film, the resist coating type can be adjusted to match the characteristics of each individual polymer film and conductive film. Adjust the
You need to choose.

From the above, it has been desired to develop a method for forming a gIL#l etching pattern (50 to 100 microns) for polymer films.

(Purpose of the Invention) The present inventors have intensively studied a method of etching a conductive thin film of a transparent conductive film as a display electrode so that there is no unevenness on the car line *m, and as a result, the present invention has been achieved. This is what I did.

(Structure of the Invention) That is, the present invention masks a conductive film on a polymer film using an aqueous solution treatment type photosensitive film resist, exposes it to a predetermined pattern, develops it, and then uses an acid aqueous solution different from the etching solution. This is a pattern forming method for a conductive film in which the conductive film is brought into contact with a conductive film and then etched.

The water-soluble process type photosensitive film resist used in the present invention may be of any alkali-developable type.

How to use it is to use Fumine V with a transparent high-polymer film and a film resist laminator! It is sufficient to expose the film to light in a predetermined pattern.

Examples of the acid aqueous solution used in the present invention and brought into contact after development include hydrochloric acid, sulfuric acid, nitric acid, acetic acid, and citric acid. The concentration of this acid varies depending on the type of acid, but generally it is sufficient to be α1% by weight or more, but it is necessary that the conductive film is hardly etched. The concentration actually used is preferably between 0.5% by weight and 10% by weight, taking into account the removal rate of defective resists such as residual development and damage to the substrate.

There are no particular restrictions on the method of contact with the acid aqueous solution, and spraying or immersion may be used.

The conductive film of the present invention includes a metal thin film such as silver, copper, or aluminum, or a metal oxide thin film such as tin oxide or indium oxide.

These thin films are applied by vapor deposition, etc., and their thickness is usually 1
00OX or less is preferable.

Note that as a vapor deposition method, a vacuum vapor deposition method, RF and DC sputtering, an ion pleating method, etc. can be used.

Generally, etching methods include elatin and etching. In the immersion method, it is also possible to use a method in which the etching solution is stirred at high speed while the conductive film is immersed to accelerate etching.

Any known etching solution can be used, but it is appropriately selected depending on the type of conductive 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 etching is preferred.

20% to 50% by weight considering the speed and damage to the substrate
Preferably between % by weight.

Further, the polymer film used in the present invention includes polystyrene and polymethyl acrylate.

Polycarbonate, polyvinyl chloride, acetate, polyethersulfone, polysulfone, polyethylene, polypropylene, polyamide, polytetrafluoroethylene,
Examples include deranutinks such as polyester.

If a pattern is formed according to the present invention, it is very easy to handle, unlike the case of using a coated photoresist, and water-soluble photosensitive film resists generally contain 1000H groups and are used for metal or metal oxidation. It easily forms chelates with substances and has good adhesion to conductive films. Also.

By contacting with an acid aqueous solution after exposure and development, it is possible to completely remove the resist residue on the line edges in minute areas where washing with water alone was not sufficient, forming a fine pattern of about 50 Inn with no irregularities in the lines. It has the advantage of being

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 was laminated with a water-soluble photosensitive film resist (Liston 3410 manufactured by Shupon Co., Ltd.), and a fine photomask for display (50μ, 60μ
, 70μ, 80μ, 100μ thin line patterns). After dissolving and removing the non-exposed portions with a dilute alkaline aqueous solution, acid treatment was performed using a 0.5% by weight sulfuric acid aqueous solution (25° C.). After this, 25% by volume aqueous acid solution (
Etching was performed at 25°C. After drying, the resist agent was peeled off with dichloroethane, and the laminated resist agent was removed and etching was completed. And 50
A micro-etched pattern with a width of .mu.m had no unevenness on the edge of the line, and a pattern with very good linearity was formed. The display electrode thus formed could be used as a dot matrix. There was no damage to the polyethylene terephthalate film.

Comparative Example 1 In the same manner as in Example 1, a thin film of ronoindium to tin oxide having a surface resistance of 300 Ω was deposited on a polyethylene terephthalate film.

Laminate the same photosensitive film resist on this,
Exposure was performed using a fine display photomask.

After leaving for 15 minutes in a dilute alkaline aqueous solution, the non-exposed areas were dissolved and removed, and then etched with a 25% by volume aqueous hydrochloric acid solution (25°C). After drying, the resist agent was removed with dichloroethane. As a result, an etching pattern with a width of 100 to 80 ILm was formed, but when it came to a pattern with a width of 70 to 50 μm, irregularities were observed in some places on the line edge, 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 80μ.

Claims (1)

[Claims] 1) The conductive film on the polymer film is masked using a water-soluble photosensitive film resist, exposed to light in a predetermined pattern, developed, and then contacted with an acid aqueous solution different from the etching solution. 1. A method for forming a pattern of a conductive film, which comprises etching the conductive film. 2) Claim 1, wherein the conductive film is tin oxide, indium oxide, or indium oxide containing tin oxide
A method for forming a pattern of a conductive film as described in Section 1. 3) The method for forming a pattern of a conductive film according to claims 1 and 2, wherein the acid aqueous solution different from the etching solution is a relatively dilute aqueous solution of the same type of acid.