JPS6288216A - Manufacture of 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> Conventionally, transparent conductive films have been used as display elements such as liquid crystal displays, electroluminescent displays, and electroluminescent displays, or as sensitive electrode materials for photoelectric conversion elements such as solar cells.

As this transparent conductive film, gold, silver,
Precious metals FfJ IIQ such as platinum and palladium are formed, as well as indium oxide, stannic oxide, indium tin oxide (ITO), and cadmium tin oxide (CTO).
Examples include those in which an oxide semiconductor thin film such as the following is formed.

Among these, transparent conductive films made of noble metal thin films have a sheet resistance of 1000/hole (Ω/hole means sheet resistance per unit square centimeter) or less, although their light transmittance is slightly inferior. It also has excellent properties such as having an electromagnetic shielding effect. On the other hand, a transparent conductive film based on an oxide semiconductor thin film has a sheet resistance inferior to that of a white metal thin film (usually 100 Ω/hole or more), but a light transmittance of 85 to 90%.
and has excellent characteristics. Generally, materials are selected as appropriate depending on the required characteristics, and the latter, oxide semiconductor thin film, is currently most widely used.

As mentioned above, these oxide semiconductor thin films used as conductive layers have a somewhat high sheet resistance, so in order to lower the sheet resistance, for example, tin oxide is used for indium oxide, and tin oxide is used for stannic oxide. A method of doping each with cadmium oxide has been used.

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, indium oxide-based materials are generally used because a film with low surface resistance can be obtained relatively easily.

As for the method of doping fluorine into the above-mentioned oxide semiconductor film such as indium oxide, a physical vapor deposition method or a chemical vapor deposition method is used. Carbon tetrafluoride
Vapor deposition is generally performed by generating plasma in a mixed gas atmosphere containing a fluorine-containing hydrocarbon gas such as CF4).

<Problems to be Solved by the Invention> According to the above-described method for producing a transparent conductive film, it is necessary to control the concentration and distribution of fluorine, which is a dopant, in the film. It is necessary to form a film while sequentially controlling the mixture ratio and partial pressure of hydrogen 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 by which a transparent conductive film with low sheet resistance can be manufactured easily and at low cost with less than 1 loss.

<Means and effects for solving the problems> In order to achieve the above object, the method for manufacturing a transparent conductive film of the present invention includes forming a lower oxide of indium doped with aluminum fluoride on a light-transmitting substrate. The method is characterized in that a film is formed, and this lower oxide film is oxidized to form an indium oxide film doped with aluminum fluoride.

That is, this invention provides a transparent conductive film that exhibits excellent properties in both light transmittance and sheet resistance, which could not be achieved with a film made of indium oxide alone, when an indium oxide film doped with aluminum fluoride is formed. This was done based on this knowledge.

Specifically, an indium lower oxide film doped with aluminum fluoride is formed on a molded body made of a polymeric material such as glass or a plastic film by a [J formation method such as a physical vapor deposition method, This lower oxide film is oxidized to form an indium oxide film doped with aluminum fluoride. As for the physical vapor deposition method as a method for forming the lower oxide film, for example, a vacuum deposition method can be employed.

Note that the doping amount of aluminum fluoride is not particularly limited, but is 1 to 20% with respect to indium oxide.
．． A range of lff1% is particularly desirable.

Further, examples of the oxidation method for the lower indium oxide film doped with aluminum fluoride include thermal oxidation in air, oxidation treatment in oxygen plasma, and ozone oxidation.

In this way, when a transparent S dielectric film is formed using an indium oxide film doped with aluminum fluoride, there is no need to use an expensive fluorine-containing hydrocarbon as a fluorine source, which is advantageous in terms of cost. In addition, a transparent IJ conductive film can be easily formed without requiring delicate control of atmospheric gas.

<Example 1> Using a mixture of indium oxide and aluminum fluoride formed into a pellet shape on a glass substrate at room temperature by vacuum evaporation method as an evaporation raw material, a 600A thick aluminum fluoride-doped indium film was prepared. A lower oxide film was formed. However, ■ The glass substrate has a thickness of 0.5 mm and a visible light transmittance of 92.
% ■ Oxygen partial pressure 3 x 10' Torr (Ultimate vacuum 2 x 10' Torr) ■ Indium oxide/aluminum fluoride = 90/10
(Weight ratio) ■ Heating temperature: 1500°C The lower oxide film obtained above has a sheet resistance of 2×10
70/mouth, visible light transmittance was 33%.

Next, the lower oxide film was thermally oxidized in air at 250° C. for 60 minutes to obtain an indium oxide film doped with aluminum fluoride. The sheet resistance of this transparent conductive film is 56
0Ω/mouth, visible light transmittance was 86%.

<Example 2> A mixture of indium oxide and aluminum fluoride was formed into a pellet shape on an air-temperature glass substrate by cluster ion beam evaporation method, and a crucible (number of nozzles: 4) was formed.
An aluminum fluoride-doped indium lower oxide film having a thickness of 800 Å was formed.

However, ■ The glass substrate has a thickness of 0.5 m + n and a visible light transmittance of 92%. ■ Oxygen partial pressure 5. X10'■orr (Ultimate vacuum level 7×
10'Torr) ■ Indium oxide/aluminum fluoride = 85/15
(Weight ratio) ■ Heating temperature 1600℃ ■ Ionization current OmA ■ Ion acceleration voltage OKV The lower oxide film obtained above has a sheet resistance of 6×10
It was 6Ω/mouth and the visible light transmittance was 27%.

Next, the lower oxide film was thermally oxidized in air at 300° C. for 30 minutes to obtain an indium oxide film doped with aluminum fluoride. The sheet resistance of this transparent conductive film is 36
0Ω/mouth, visible light transmittance was 85%.

<Example 3> A mixture of indium oxide and aluminum fluoride was molded into a pellet shape on an air-temperature polyester film substrate using a cluster ion beam evaporation method, and then supplied into a crucible (number of nozzles: 4). An aluminum fluoride-doped indium lower oxide film having a thickness of 400 Å was formed.

However, ■ The polyester film substrate has a thickness of 100 mm and a visible light transmittance of 90%. ■ Oxygen partial pressure is 5 x 10-4 Torr (Ultimate vacuum level is 6 x 10-7 Torr). ■ Indium oxide/aluminum fluoride = 90/10.
<11 amount ratio) ■ Heating temperature 1600℃ ■ Ionization current 50mA ■ Ion acceleration voltage IKV The lower oxide film obtained above has a sheet resistance of 8×10
It was 7Ω/mouth, and the visible light transmittance was 40%.

Next, the lower oxide film was thermally oxidized in air at 200° C. for 60 minutes to obtain an indium oxide film doped with aluminum fluoride. The sheet resistance of this transparent conductive film is 72
0Ω/mouth, visible light transmittance was 87%.

<Comparative example> When a lower oxide film of indium alone was formed under the same conditions as in Example 1 without doping with aluminum fluoride, the sheet resistance was 7 x 10 Ω/hole and the visible light transmittance was 30%. A film was obtained.

Next, the above lower oxide film was subjected to Illization in air at 250° C. for 30 minutes in the same manner as in Example 1, to obtain an indium oxide film doped with aluminum fluoride. This transparent conductive film had a sheet resistance of 5×10′Ω/hole and a visible light transmittance of 85%.

As described above, the transparent conductive film produced according to the present invention is
It is clear that good optical transparency can be exhibited and low sheet resistance can be achieved.

<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 surface resistance can be produced without using an expensive fluorine-containing hydrocarbon as a fluorine source. In addition, it has the unique effect of not requiring delicate control of atmospheric gas and facilitating manufacturing.

Claims (1)

[Claims] 1. Forming an indium lower oxide film doped with aluminum fluoride on a light-transmitting substrate, and oxidizing this lower oxide film to form an indium oxide film doped with aluminum fluoride. A method for producing a transparent conductive film characterized by: