JPS61260505A - 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] [Field of Application of the Invention] The present invention relates to a method for producing a transparent conductive film, which allows a desired transparent conductive film to be formed on a substrate with low heat resistance at low temperature and at high speed with good reproducibility. be.

[Background of the invention]

Generally speaking, a sputtering method is used to form a transparent conductive film on a substrate using InzOsSn as a target.
Two methods have been proposed: a method in which O2 oxide or the like is sputtered in an Ar gas atmosphere, and a method in which In-8n alloy or the like is sputtered in a mixed gas of Ar and O2. In the former method, a film with low electrical resistance and high light transmittance can be formed immediately after sputtering, but it is difficult to increase the film formation rate. On the other hand, in the latter case, although the film formation rate is high, the range of film formation conditions that allow a film with low electrical resistance and high light transmittance to be obtained without substrate heating or heat treatment is extremely narrow, making film formation control extremely difficult. There was a drawback.

On the other hand, Japanese Patent Laid-Open No. 56-9905 reports a method in which a vapor deposited film formed by vacuum evaporation is subjected to oxidation treatment by using metal indium as an evaporation source and including water vapor in an oxidizing gas atmosphere.

[Purpose of the invention]

Therefore, the present invention has been made in view of the above-mentioned conventional problems, and its purpose is to create a transparent conductive film that enables the formation of a transparent conductive film at high speed and with good reproducibility without raising the substrate temperature. The purpose is to provide a manufacturing method.

[Summary of the invention]

In order to achieve such an object, the present invention accurately controls film formation by applying a bias voltage to the substrate holder during sputtering and controlling the film quality of the transparent conductive film.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a cross-sectional view of a main part of a sputtering apparatus for illustrating an example of a method for manufacturing a transparent conductive film according to the present invention. In the figure, 1 is a sputtering device, 2 is a holder for holding a substrate on which a transparent conductive film is to be formed, 3 is a target made of In-8n alloy and placed opposite to the holder 2, and 4 is a sputtering device.
is a substrate mounted on the holder 2, 5 is a power source that applies high voltage to the target 3, 6 is a mass 70-controller that controls the flow rate of oxygen (O2), and 7 is a mass that controls the flow rate of argon (Ar). 70 - controller, 8 is holder 2
A bias power supply is used to apply voltage to the

In the sputtering apparatus configured in this way, first, a mixed gas of argon gas and oxygen gas of a factor of 10 is introduced into the sputtering apparatus 1 by the mass 70-controllers 26, 7, and a voltage is applied to the target 3. Then, the In-8n alloy of the target 3 is sputtered onto the opposite surface of the substrate 4. A power source 5 that applies voltage to this target 3
For example, by fixing the input power and argon gas flow rate and increasing the oxygen gas flow rate without applying a bias voltage, a transparent conductive film can be formed using film formation parameters such as the input power, oxygen and argon gas flow rates, and voltage of the bias power supply. When a film is formed, the quality of the transparent conductive film changes as shown in FIG. That is, in the same figure, 02 indicates the minimum value of sheet resistance.
On the low oxygen flow rate side, the film forms a black, indium-rich lower oxide), and on the high oxygen flow side, the film forms a transparent, high-resistance oxide. The film formation rate changes rapidly in the region where this lower oxide changes to a high resistance oxide with a stoichiometric composition, and in region A where this rapid change in film formation rate occurs, low electrical resistance and high light transmission occur. A transparent conductive film having a high conductivity was obtained.

However, this film-forming area A varies greatly depending on the surface condition of the target 30, so even if the oxygen flow rate is optimized in advance and film-forming conditions are fixed, the optimal film-forming area is narrow and a high-quality film cannot be obtained. It was difficult to form a film with good reproducibility.

Therefore, in the present invention, after optimizing the oxygen flow rate in advance, the film forming parameters such as the input gas and the oxygen and argon gas flow rates are fixed, and the bias voltage applied to the substrate holder 2 is made variable. The thickness of the transparent conductive film is controlled by this bias voltage.As shown in Figure 3, by increasing or decreasing the bias voltage, the quality of the transparent conductive film gradually changes and a high quality film can be obtained. The bias voltage range is wide, so film quality can be easily controlled.

The present invention will be explained in detail below.

First, an In-5wt%Sn alloy was used for the target 3, and the distance between the substrate 4 and the target 3 was 12011 ml.

Argon gas flow rate 65SCCM, oxygen gas flow rate 158
The input power of the CCM was fixed at 200 W with direct current, the substrate 4 held in the holder 2 was made of underglass, and the bias power supply 8 was a direct current power supply. Here, the bias power supply 8 is Ov
It should be possible to vary between ~+100v.

Under the above film forming conditions, a transparent conductive film is formed by changing only the bias voltage applied to the substrate 4, and the bias voltage applied to the substrate holder 2 is optimized based on the quality of the obtained film. As a result, the latitude for film formation was improved, and a transparent conductive film having low electrical resistance and high light transmittance could be obtained at low temperature with good reproducibility.

The inventors have already reported in Japanese Patent Application No. 56-192935 that the emission line intensities of indium and oxygen in the plasma were measured during film formation, and feedback was applied to the film formation parameters so that this ratio remained constant. It has been shown that reproducibility is improved. Reproducibility is further improved when the bias voltage to the substrate according to the present invention is used as the film forming parameter to which this feedback is applied.

According to such a method, a high-quality transparent conductive film can be produced with good reproducibility at a temperature of the substrate 4 of about 100° C. or lower and a film formation rate of 600 cm or higher. In this case, the film characteristics differ somewhat depending on the type and material of the substrate 4, but for example, in the case of a transparent conductive film with a film thickness of about 300X formed on soda glass in the above example, the sheet resistance is about 100Ω/gate, and the wavelength A light transmittance of about 88% was obtained at 500 nm.

In this example, In-5wt%S was added to the target 3.
Although n is used, the present invention is not limited thereto, and may also be In+Sn+Sn, Sb, Zn, etc. Furthermore, in the case of an alloy, the same effect can be achieved even if the composition ratio is changed.

In addition, in this example, the case where oxygen was used as the oxidizing gas was explained, but the same effect can be obtained when using an oxidizing gas such as COz gas r Nz O gas or a mixed gas of these and oxygen gas. Effects can be obtained.

Further, the bias power source 8 is not limited to a DC power source, but may also be a high frequency power source and the same effect can be obtained.

〔Effect of the invention〕

As explained above, according to the method for manufacturing a transparent conductive film according to the present invention, a transparent conductive film can be formed at high speed and with good reproducibility without increasing the substrate temperature, and the substrate temperature can be raised to a high temperature. Even on substrates with low heat resistance such as plastic substrates, polarizing plates, etc., an extremely excellent effect can be obtained in that the transparent conductive film can be formed at low temperature and at high speed, and the film quality can be easily controlled.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a main part of a sputtering apparatus for explaining an example of the method for forming a transparent conductive film according to the present invention, and FIG. 2 shows changes in sheet resistance and light transmittance with respect to oxygen flow rate of the transparent conductive film. A characteristic diagram, FIG. 3, is a characteristic diagram showing changes in sheet resistance and light transmittance of a transparent conductive film with respect to bias voltage when a film is formed with fixed input power, argon, and oxygen flow rates. 1... Sputtering device, 2... Substrate holder, 3...
...Target, 4...Substrate, No.5...φ power supply%
6...Oxygen gas mass flow controller 7 II
@...Argon gas mass flow controller, 8...
bias ti.

Claims (1)

[Claims] In a method for producing a transparent conductive film in which a transparent conductive film is formed on a substrate by sputtering a metal in a mixed gas of an inert gas and an oxidizing gas, a bias voltage is applied to the substrate during the sputtering to form a transparent conductive film. A method for producing a transparent conductive film characterized by controlling film quality.