JPS6280918A - Manufacturing transparent 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] <Industrial application field> The present invention relates to a method for manufacturing a transparent conductive film.

More specifically, the present invention relates to a method of forming a transparent conductive film on a light-transmitting substrate made of glass, polymeric material, or the like.

<Prior art and problems to be solved by the invention> Conventionally, transparent conductive films have been used as window electrode materials for display elements such as liquid crystal displays, electroluminescent displays, and electrochromic displays, or for photoelectric conversion elements such as solar cells. has been done.

As this transparent conductive film, gold, silver,
Precious metals such as platinum and palladium are formed, and indium oxide, stannic oxide, and indium tin oxide (
Examples include those in which a single film of an oxide semiconductor such as ITO) or cadmium tin chloride (CTO) is formed.

Among these, transparent conductive films made of noble metal thin films have a slightly inferior light transmittance, but can easily have a sheet resistance of 100 Ω/hole (Ω/hole means sheet resistance per unit square centimeter), and It has excellent properties such as having an electromagnetic shielding effect. On the other hand, a transparent conductive film made of an oxide semiconductor thin film has a sheet resistance inferior to that of a noble metal thin film (usually 100 Ω/hole or more), but a light transmittance of 85 to 90%.
and has excellent characteristics. In general, materials are selected as appropriate depending on the required characteristics, and there is currently a wide range of materials available (the latter, oxide semiconductor thin films, are in use).

These oxide semiconductor films are used as the conductor'fR layer.
As mentioned above, the sheet resistance is rather high, so in order to lower the sheet resistance, for example, indium oxide is doped with stannic oxide, and stannic oxide is doped with cadmium oxide.

In addition to these methods of doping a different type of oxide semiconductor, a method of doping fluorine into an oxide semiconductor film of indium oxide, stannic oxide, or the like has also been used.

Among these materials, indium oxide-based materials are generally used because films with low surface resistance can be obtained relatively easily, but indium oxide is less expensive than other transparent conductive film materials. The problem is that (chemical costs) are quite high.

Therefore, recently, methods of forming a film by physical vapor deposition or chemical vapor deposition using inexpensive zinc oxide have been studied. However, according to this method, the light transmittance is slightly inferior to the case of using indium oxide-based materials, and the sheet resistance is also high (e.g., electrodes of liquid crystal display elements, window electrodes of photoelectric conversion elements such as solar cells). There is a problem in that it is difficult to use in applications that require particularly low sheet resistance.

On the other hand, physical vapor deposition or chemical vapor deposition is used to dope fluorine into an oxide semiconductor film such as stannic oxide. If carried out, carbon tetrafluoride (
Generally, deposition is performed by generating plasma in a mixed gas atmosphere containing a fluorine-containing hydrocarbon gas such as CF4), but it is necessary to control the concentration and distribution of fluorine, which is a dopant, in the film. Therefore, it is necessary to perform film formation while sequentially controlling the mixing ratio and partial pressure of the fluorine-containing hydrocarbon gas in the mixed gas, which is a problem when it is carried out industrially. Another problem with fluorine-containing hydrocarbon gas is that it is rather expensive.

Purpose The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a method for manufacturing a transparent conductive film with low sheet resistance easily and at low cost.

Means and Effects for Solving the Problems> The method for manufacturing a transparent conductive film of the present invention to achieve the above object includes forming a zinc oxide film doped with aluminum fluoride on a light-transmitting substrate. It is characterized by

That is, the present invention provides that when a zinc oxide film doped with aluminum fluoride is formed by a thin film forming method such as physical vapor deposition, light transmittance and sheet resistance that could not be achieved with a film made of zinc oxide alone can be achieved. This invention was based on the discovery that it was possible to obtain a transparent conductive film that exhibited excellent properties on both sides.

Specifically, FIJIgI of zinc oxide doped with aluminum fluoride is formed on a molded body made of a polymeric material such as glass or a plastic film by a Si formation method such as a physical vapor deposition method. As the above-mentioned thin film forming method, sputtering method, ion blating method, vacuum evaporation method, etc. can also be adopted.

In the above manufacturing method, the amount of aluminum fluoride doped in the zinc oxide film is not particularly limited, but is particularly preferably in the range of 1 to 20% by weight relative to zinc oxide.

Further, the thickness of the zinc oxide film doped with aluminum fluoride may be appropriately selected depending on the application.
When a zinc oxide film doped with 5ffffj% aluminum fluoride and having a thickness of 200 OA is formed using the RF sputtering method, a sheet resistance of 210 Ω/hole is obtained. Note that the sheet resistance of a zinc oxide film alone without doping with aluminum fluoride is 105 Ω/portion, and by doping with aluminum fluoride, the conductivity can be significantly reduced.

In this way, when forming a transparent conductive film using a zinc oxide film doped with aluminum fluoride, there is no need to use expensive materials such as indium oxide, and it is also possible to use expensive fluorine-containing carbide as a fluorine source. Since there is no need to use hydrogen, it is advantageous in terms of cost. However, a transparent conductive film can be easily formed without requiring delicate control of atmospheric gas.

<Example 1> A transparent conductive film made of a zinc oxide film doped with aluminum fluoride was formed on a glass substrate under the following conditions.

■Substrate thickness 0.5M Visible light transmittance 92% ■Equipment used RF sputtering equipment Target Zn O/A I F3-97/3 (multilayer ratio)
Sintering after hot pressing ■RF input power 200W ■Used gas Ar gas Gas pressure 6. OX 10'Torr ■Film thickness 250OA (Measured using a multiple reflection type floating microscope) As a result, the light transmittance for visible light with a wavelength of 400 to 800 nm (hereinafter the same) is 82% or more, and the sheet resistance is 482Ω.
/ A transparent conductive film was obtained.

<Example 2> A transparent conductive film made of a zinc oxide film doped with aluminum fluoride was formed on a glass substrate under the following conditions.

■Substrate thickness 0.5mm Visible light transmittance 92% ■Equipment used RF magnetron sputtering device ■Target Zn O/A I F3-951
5 (weight ratio) Sintering after hot pressing ■RF input power 150W ■Used gas Ar gas gas pressure 1, OX 10'Torr ■Film thickness 200OA As a result, the light transmittance is 80% or more and the sheet resistance is 180Ω/
A transparent conductive film was obtained.

<Example 3> A transparent conductive film made of a zinc oxide film doped with aluminum fluoride was formed on a glass substrate under the following conditions.

■Substrate thickness 0.5mm Visible light transmittance 92% ■Bag used RF ion brating device ■Target Zn O/A I F3=90/1
After mixing the 0 (weight ratio) powder, it is formed into pellets and sintered ■ RF input power 200 W ■ Gas used Mixed gas of Ar and 02 (Ar10
2=80/2G) Gas pressure5. OX 10'Torr ■Film thickness 1500A As a result, light transmittance is 75-80% and sheet resistance is 1300
A transparent conductive film of Ω/mouth was obtained.

<Example 4> A transparent conductive film made of a zinc oxide film doped with aluminum fluoride was formed on a polyester film substrate under the following conditions.

■Substrate thickness: 10 (1m) Visible light transmittance: 90% ■Equipment used: RF magnetron sputtering equipment ■Target: Zn O/A I F3=951
5 (weight ratio) Sintering after hot pressing ■RF input power 100W ■Used gas Ar gas Gas pressure 8. Qx 10'Torr ■Film thickness 1000A As a result, the light transmittance is 83% or more and the sheet resistance is 6700/
A transparent conductive film was obtained.

Comparative Example 1> When a zinc oxide film was formed using a zinc oxide sintered body as a target and under the same conditions as in Example 1, the light transmittance was 70 to 75% and the sheet resistance was 8X10'. Ω/
It was the mouth.

Comparative Example 2> When a zinc oxide film was formed using a zinc oxide sintered body as a target and under the same conditions as in Example 2, the light transmittance was 70-80% and the sheet resistance was 1. 0X104
It was Ω/mouth.

Comparative Example 3 When a zinc oxide film was formed using a zinc oxide sintered body as a target and under the same conditions as in Example 3, the light transmittance was 80% or more and the sheet resistance was 1.0×101Ω.
/It was a mouth.

From the above, it is clear that a transparent conductive T@ film made of a zinc oxide film doped with aluminum fluoride exhibits good light transmittance and can achieve a reduction in sheet resistance.

<Effects of the Invention> As described above, according to the method for producing a transparent conductive film of the present invention, a transparent conductive film with low sheet resistance can be produced without using expensive indium oxide or fluorine-containing hydrocarbons. In addition, it has the unique effect of not requiring delicate control of atmospheric gas and facilitating manufacturing.

Claims (1)

[Claims] 1. A method for producing a transparent conductive film, which comprises forming a zinc oxide film doped with aluminum fluoride on a light-transmissive substrate.