JPS5956313A - Method of producing thin conductive 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 The present invention relates to a method for producing a conductive thin film, and in particular to a method for producing a transparent conductive polyethylene terephthalate film base** having excellent alkali resistance.

In general, thin films that are transparent in the visible light range and have conductivity are used as transparent electrodes in new display systems such as liquid crystal displays and electroluminescent displays, as well as for preventing static electricity on transparent articles and blocking electromagnetic waves. ing.

Conventionally, so-called conductive glass, in which an indium oxide film is formed on glass, has been well known as such a transparent conductive thin film, but because the base material is glass, it has poor flexibility and processability. This may be undesirable depending on the application. Therefore, in recent years, transparent conductive thin films based on synthetic resins have come into use due to their advantages such as flexibility, processability, excellent impact resistance, and light weight. Polyethylene terephthalate film is preferably used as the base film because it has excellent heat resistance, strength, and the like.

For example, in order to use a transparent conductive thin film as a transparent electrode, it is patterned into a predetermined shape, and in this process, acids and alkalis are often used. On the other hand, polyethylene terephthalate films are generally hydrolyzed by acids or alkalis to roughen their surfaces.

Therefore, when the conductive thin film formed on this film is inferior to the film, the film does not lose its transparency during or after the patterning process, and the thin film may peel off. So, to get 1 high & quality Φ transparent electrode,
11 #1 membrane'L that can be obtained and obtained together with Na1
Good: Inferior to durability and durability.

The present invention was made in order to solve the above-mentioned problems.It is stable against alkalis and k, and therefore improves adhesion, transparency, and toughness. Our aim is to provide a method for producing a conductive film with excellent conductivity and durability.

The misfire is a method of forming a conductive thin film on the surface of a polyethylene terephthalate film in a vacuum.
The above film was then treated with at least 65.0% argon.
Containing i K 1110-3= A * ToffO
In the atmosphere of yr:, It II~, '3 i
(l W・sec/CM・range: high, 1
The feature is that a conductive thin film is formed by performing a frequency sputter etching process, and then maintaining a vacuum of 1 degree (substantially 1 degree).

Sputter etching place! ! ! ! Although the process of etching is already well known, the present invention is characterized by the fact that the atmosphere in which the film on the polyethylene terephthalate base material is sputter-etched contains at least argon. 5. The atmosphere gas must contain argon, preferably 80% or more, of argon.
IL, To obtain a conductive thin film of 1J ethicine terephthalate film JA copolymer with excellent fluorocarbon resistance 1)
This is extremely important, as is the case with argon, an atmosphere mainly composed of inert nitrogen, helium, etc.
However, it is not possible to use a conductive bamboo thin film with excellent alkali resistance. it
The gas composition may be a gas normally used in the sputter etching process, such as nitrogen, neon, hydrogen, or air, and the gas may contain water vapor. In addition, the atmospheric pressure is also important, and 'l
@-3~1 x IIQ ”T,,rr:tp3 range,
It is necessary that the Glow discharge tends to become unstable in a vacuum higher than the above range, whereas in a vacuum lower than the above range, the effect of improving the adhesion of the base film to the conductive thin film by spack etching treatment □ Φ high i frequency per area, wave force (W/4)
'9, discharge treatment amount 221', 10, 1-. 3 @W-sec/- value: Below the above range, the processing effect is not sufficient, and above the above range, the film may be deformed,
It is not preferable or undesirable because it may cause coloring. :RJl, Taka・
frequency, the supplied power source ・' is the practical industrial allocation: frequency 1
It is convenient to use liL5.6M,.H,z.

The method of the present invention has one important feature in that a conductive film can be formed while substantially maintaining the degree of vacuum in the sputter-etched atmosphere as described above.

Here, "maintaining substantially the N density of the sputter etching process" means the above-mentioned 1x10-3 to iXi
This means forming conductive crotches on the film surface in the next step without breaking the vacuum in the range of 'Or, orr, and in this vacuum range. However, the atmospheric gas composition does not necessarily have to be the same, and may be changed as appropriate depending on the method of forming the conductive thin film employed. On the other hand, after sputter etching the film at the above vacuum level, the film was taken out in the air and
Even if we form conductivity again in a predetermined vacuum zero plane, the principle 111B,' is not necessarily clear.
However, the resulting conductive thin 7 film has poor alkali 1J resistance.

In the present invention, after spuck etching the base polyethylene telex sheet film, the degree of vacuum is maintained as described above, and a conductive thin film is formed at the zero vacuum level. Any method can be used to form one film. A method of forming such a conductive thin film,
For example, as is well known, vacuum evaporation method, sputtering method, ion blating method, etc. can be mentioned. Furthermore, the thin film material is not particularly limited and is non-poisonous; for example, indium oxide containing tin oxide, tin oxide containing antimony, etc. are preferably used. It is formed to a thickness of approximately tens of thousands of people. However, the method of the present invention is particularly effective when forming an indium oxide-tin oxide conductive thin film by a vacuum evaporation method, a sputtering method, etc., and has excellent alkali resistance, and therefore has low sheet resistance and durability. A highly conductive thin film can be obtained.

As mentioned above, the atmospheric pressure for forming the conductive thin film is 1
×10-3 to 1×10 Torr; however, if the vacuum is lower than the above range, the thin film formation efficiency will be poor, and if the vacuum is higher than the above range, the resulting film will not be transparent in the visible light region. This is undesirable because it reduces performance.

In the present invention, the base film only needs to have a surface made of polyethylene terephthalate, and therefore may of course be a laminated film with another resin film having a surface layer of polyethylene terephthalate.

As described above, according to the present invention, a polyethylene terephthalate film as a base material is subjected to sputter etching treatment in a vacuum atmosphere consisting of a predetermined gas, and then, while the degree of vacuum in the atmosphere is substantially maintained, conductive The conductive thin film obtained by this method has low resistance and excellent chemical resistance, particularly alkali resistance, and therefore has excellent adhesion to the film and durability.

Examples of the present invention are listed below along with comparative examples, but the present invention is not limited to these Examples in any way. In addition, in the following, the alkali resistance of the obtained polyethylene terephthalate film base conductive thin film was evaluated as follows.

That is, the film was cut into strips with a width of 1 cm, and heated at 60°C.
The sheet resistance of the conductive thin film was measured after being immersed in a heated 1% aqueous sodium hydroxide solution in a constant temperature bath for 5 minutes, and the alkali resistance was evaluated based on the rate of change. This operation was repeated until the conductive thin film was peeled off from the film. Furthermore, a four-terminal method was used to measure the sheet resistance.

Example 1 Polyethylene terephthalate film with 80% argon
Sputter etching was performed at a discharge treatment rate of 3 W·sec/C♂ in an atmosphere of 4×10′ Torr containing 20% oxygen. Thereafter, without breaking the vacuum and in the same atmospheric gas, a 400 mm thick indium oxide-tin oxide conductive thin film (hereinafter referred to as an ITO film) was formed by reactive sputtering using an indium-tin alloy. .) was formed. The sheet resistance of this film is 200Ω/
He showed his mouth.

When this film base conductive thin film was immersed in a heated sodium hydroxide aqueous solution as described above and the sheet resistance was measured over time, the sheet resistance increased only to 1.6 times the initial value even after 50 minutes of immersion. There wasn't. On the other hand, for comparison, an ITO film was obtained in exactly the same manner as above except that the base film was not subjected to sputter etching treatment, and when it was immersed in an aqueous sodium hydroxide solution, the film peeled off from the film after only 10 minutes. .

In addition, after sputter etching the film, it is taken out into the atmosphere and then IT is etched in the same atmosphere as above.
Although an O film was formed, the sheet resistance of this film reached 7 times the initial value 50 minutes after being immersed in the aqueous sodium hydroxide solution.

Example 2 A laminated film in which polyethylene terephthalate films were adhered and laminated on both sides of a polyvinyl alcohol film with an adhesive was used as a base film. This base film was made of 8×1 consisting of 80% argon and 20% oxygen.
Discharge processing amount 10W・sec/d in an atmosphere of 0 Torr
Sputter etching treatment was carried out. Next, while maintaining this vacuum atmosphere and heating the base film to a temperature of 100° C., an ITO film was formed by a binary vacuum evaporation method of indium and tin. This membrane is 400 people thick,
The sheet resistance was 300Ω/mouth.

Even after this film was immersed in an aqueous sodium hydroxide solution for 50 minutes, the sheet resistance increased only 2.5 times its initial value. However, for comparison, a film obtained in the same manner as above except that the base film was not subjected to sputter etching treatment was
The film peeled off from the film after being immersed for a minute, and after the sputter etching process, the film was taken out into the atmosphere and
After that, the film formed in the same vacuum atmosphere as above was immersed in a caustic soda aqueous solution for 50 minutes, and its sheet resistance reached 13 times the initial value.

Example 3 Polyethylene terephthalate film with 60% argon
Sputter etching treatment was performed at a discharge treatment rate of 0.5 W·sec/c++I in a vacuum atmosphere of I x 10 Torr containing 40% oxygen. Next, while maintaining this vacuum atmosphere, an ITO film was obtained by electron beam evaporation using an indium oxide-tin oxide target. Thereafter, this film was heat-treated at a temperature of 90°C to obtain a transparent conductive ITO film.

This membrane had a thickness of 400 Ω and a sheet resistance of 350 Ω/mouth.

Even after this film was immersed in an aqueous sodium hydroxide solution for 50 minutes, the sheet resistance increased only three times its initial value. However, for comparison, a film obtained in the same manner as above except that the base film was not subjected to sputter etching treatment was
The film peeled off from the film after being immersed for a minute, and after the sputter etching process, the film was taken out into the atmosphere and
After that, the film formed in step 1 in the same vacuum atmosphere as above was immersed in an aqueous sodium hydroxide solution for 50 minutes, and its sheet resistance reached 15 times its initial value.

Comparative Example A TO film was obtained in exactly the same manner as in Example 1, except that the atmospheric gas for sputter etching the film was 80% nitrogen and 20% oxygen. This membrane had a thickness of 400 Ω and a sheet resistance of 200 Ω/mouth.

When this membrane was immersed in a heated aqueous sodium hydroxide solution,
After 10 minutes, the sheet resistance increased to 3 times its initial value and reached 20
The membrane peeled off from the film after minutes.

2 58

Claims (1)

[Claims] (11 In a method of forming a conductive thin film on the surface of a polyethylene terephthalate film in vacuum, the above film contains at least 50% argon.
3~1×lθ In an atmosphere of 6tr, 0.1~3
1. A method for producing a conductive thin film, which comprises performing a high frequency sputter etching treatment with a discharge treatment amount in the range of 0 W·sec/-, and then forming a conductive IF film while substantially maintaining the degree of vacuum.