TWI500081B - Cleaning method of transparent electrode film - Google Patents

Description

Transparent electrode film cleaning method

In recent years, transparent electrodes have been indispensable as electrodes for solar cells, liquid crystals, and organic ELs. As a material of the transparent electrode, zinc oxide has an advantage that the material is easily obtained, and good crystals having high transparency can be obtained.

Generally, a film forming system of an oxide film of a plasma is used. When an oxide film is formed, the oxide film adheres to the inner wall surface of the processing chamber or the surface of various devices existing in the processing chamber (hereinafter referred to as a processing chamber surface). When the oxide film of the product is adhered to the inside of the processing chamber as it is, and the film forming operation is repeated, the plasma discharge current value becomes unstable, and the film adhering to the inside of the processing chamber is peeled off, resulting in the peeling film. The composition adheres to the substrate to deteriorate the film quality of the film formed on the substrate.

Therefore, in order to clean the inside of the processing chamber and remove the adhered film in the film forming system of the oxide film, the system for forming the zinc oxide film cannot be removed by the chlorine trifluoride gas used for gas cleaning in the plasma film forming apparatus. It is a wet cleaning with acid cleaning. However, wet cleaning requires maintenance accompanying the decomposition of the device. In addition to the problem of reduced productivity, the zinc oxide film is a film that easily adsorbs moisture, so once the number of repairs increases, the film quality and the true room are adversely affected. The problem.

In the system for forming a zinc oxide film, a cleaning method for treating the inside of a chamber using a mixed gas of methane and hydrogen as a cleaning gas has been proposed. (Patent Document 1)

[prior technical literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2010-3872

In the mixed gas atmosphere of methane-hydrogen proposed in the prior art, it is necessary to stop the supply of methane gas from the middle of the cleaning process, which has a problem that the operation of the cleaning process is troublesome.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for cleaning a zinc oxide film which reliably removes an adhered zinc oxide film in a simple operation sequence.

In order to achieve the above object, the present invention is characterized in that a hydrogen-rich methane chloride-hydrogen mixed gas is used as a cleaning gas.

In order to achieve the above object, in the invention according to the first aspect of the invention, when the zinc oxide film adhering to the inside of the processing chamber of the transparent conductive film generating apparatus which is a transparent conductive film to form a zinc oxide film is cleaned, the processing chamber is chlorinated. The methane gas and the hydrogen gas form a hydrogen-rich hydrogen chloride-methane-hydrogen mixed gas atmosphere, and the plasma is generated in the treatment chamber in the mixed environment of the chlorinated methane-hydrogen gas to remove the zinc oxide film adhering to the inside of the processing chamber.

Further, in the invention according to the second aspect of the invention, when the transparent conductive film attached to the inside of the processing chamber in which the transparent conductive film containing zinc oxide is formed is cleaned, the processing chamber is rich in chlorinated methane gas and hydrogen gas. Contain The hydrogen chloride-methane-hydrogen mixed gas atmosphere is characterized in that a plasma is generated in a treatment chamber in the mixed environment of the chlorinated methane-hydrogen gas to remove a transparent conductive film adhering to the inside of the processing chamber.

In the present invention, since the cleaning gas is used as a hydrogen-rich hydrogenated methane-hydrogen gas mixed gas, a carbon-based film is not formed, and a zinc oxide film or a transparent electrode film containing zinc oxide as a main component can be surely removed at a high etching rate. . As a result, in addition to the fact that the deposit can be removed by a simple operation, the problem of film peeling or poor insulation caused by the deposition of the zinc oxide film can be prevented, contributing to an improvement in quality or throughput.

A plasma or ion plating film forming apparatus to which the present invention is applied, as schematically shown in Fig. 1, has a gas-tight vacuum processing chamber (1); and is disposed on one side wall of the vacuum processing chamber (1) ( 2) a plasma gun (3) acting as a cathode; a hearth (5) provided as an anode function in the bottom wall (4) of the vacuum processing chamber (1); disposed in the vacuum processing chamber (1) a substrate transfer device (6) for transporting a workpiece of a film formation object on the upper wall; a horizontal door (7) constituting an upper wall of the vacuum processing chamber (1); and a surface opposite to the plasma gun (3) The state of the dummy anode (8).

The plasma gun (3) irradiates the hearth (5) with a plasma having a plasma gun body (9) for generating a plasma beam (P); and a plasma gun body (9) The vacuum processing chamber (1) side is formed by an intermediate electrode (10) disposed coaxially with the plasma gun body (9). Further, the plasma gun body (9) is a negative terminal to which the conductor plate (11) is connected to the direct current power source (12), and a discharge is generated between the conductor plate (11) and the hearth (5) to generate a plasma. Bunch (P). A permanent magnet is placed in the intermediate electrode (10), by which the plasma beam (P) generated by the plasma gun (3) is concentrated.

The hearth (5) has a magnetic field generating function for attracting the plasma beam (P), is formed of a conductive material, and is connected to the positive terminal of the pre-recorded DC power source (12). In the hearth (5), a through hole (13) is formed in a central portion where the plasma beam (P) is incident, and a cylindrical ingot (14) is filled in the through hole (13). An insulating tube (15) is provided around the through hole (13), and the hearth (5) and the ingot (14) are insulated in the processing chamber. Further, the ingot (14) is a material material (evaporated material) to be formed, and the electroconductive holder (16) holding the ingot (14) is a positive terminal connected to the DC power source (12).

The dummy anode (8) is disposed in a state of being opposed to the mounting wall surface (2) of the plasma gun (3), and is connected to the positive terminal of the DC power source (12). The virtual anode (8) is provided, whereby the generation of the magnetic field, the scattering effect of the refracted magnetic field or the influence of the evaporation material on the hearth (5) can be reduced due to the reduction of the discharge of the furnace bed (5) of the main anode. It is easy to generate plasma ignition, and at the same time, it can get stable state quickly.

Further, although omitted from the drawing, a cleaning gas introduction pipe is connected to the wall surface of the vacuum processing chamber (1).

In the case where a zinc oxide film is formed on a substrate by using a plasma or ion plating film forming apparatus having the above-described configuration, the surface of each part in the processing chamber is also adhered. The film forming component of zinc oxide. When the zinc oxide in which the film-forming component is not removed on the surface of each part in the processing chamber continues to operate, the plasma discharge current value is unstable, or the film attached to the inside of the processing chamber is peeled off, and the components of the peeled film adhere to the substrate. The film quality of the film formed on the substrate is deteriorated.

The present invention is a method for removing zinc oxide which is a film-forming component adhering to the surface of each portion in the processing chamber by gas cleaning, and as the cleaning gas, a hydrogen-rich methane chloride-hydrogen mixed gas is used. When the zinc oxide film is cleaned by a mixed gas of chlorinated methane and hydrogen, the zinc oxide is mainly dimethyl zinc and is removed as a gas.

In order to detect the cleaning effect by the cleaning gas, the sample in which the zinc oxide film is adhered to the surface of the SUS plate is cleaned by using a hydrogen-rich hydrogen chloride gas which changes the mixing ratio. The results are shown in Table 1.

It is known from Table 1 that when hydrogen is added to the methyl chloride for 10 times or more, the etching effect is particularly enhanced. Further, the methyl chloride monomer was not etched, and the film formation of the carbon-based film was dominated, and it was confirmed that the hydrogen carrier had a very small etching rate.

Next, in Table 2, it is confirmed that the pressure dependence of the gas (pressure The result of dependence).

It is known from Table 2 that it is desirable to treat the environmental pressure at the time of the cleaning treatment in a vacuum state lower than 60 Pa.

In these cases, when a hydrogen-rich methane chloride-hydrogen mixed gas is used as the cleaning gas for the zinc oxide film, the zinc oxide film can be removed without depositing carbon.

Further, in the present embodiment, although pure ZnO is described, when an actual transparent conductive film or the like is produced, an element of a few % of valence ions (Al ₂ O ₃ or Ga) is added for the purpose of improving conductivity. ₂ O _{3 ,} etc., the same effect can be obtained in the application of these materials.

[Industrial Availability]

According to the present invention, when zinc oxide is used as the material of the transparent electrode, the gas can be cleaned in the processing chamber. Therefore, the zinc oxide film can be used as an electrode of a solar cell, a liquid crystal, or an organic EL.

1‧‧‧vacuum processing room

2‧‧‧ side wall

3‧‧‧Plastic gun

4‧‧‧ bottom wall

5‧‧‧ hearth

6‧‧‧Substrate transport device

7‧‧‧ horizontal door

8‧‧‧Virtual anode

9‧‧‧Plastic gun body

10‧‧‧Intermediate electrode

11‧‧‧Conductor board

12‧‧‧DC power supply

13‧‧‧through holes

14‧‧‧ ingots

15‧‧‧Insulation tube

16‧‧‧Electrical spindle

P‧‧‧plasma beam

Fig. 1 is a schematic configuration diagram of a plasma or ion plating film forming apparatus to which the method of the present invention is applied.

Claims (3)

A method for cleaning a transparent electrode film, characterized in that, when cleaning a zinc oxide film attached to a processing chamber surface of a transparent conductive film generating device which is a transparent conductive film to form a zinc oxide film, methane chloride gas is treated in the processing chamber The hydrogen gas forms a hydrogen-rich hydrogen chloride-methane-hydrogen mixed gas atmosphere, and plasma is generated in the treatment chamber in the mixed environment of the hydrogen chloride-methane hydrogen gas to remove the zinc oxide film adhering to the inside of the processing chamber. A method for cleaning a transparent electrode film, characterized in that, when cleaning a transparent conductive film attached to a processing chamber surface of a transparent conductive film containing zinc oxide as a main component, the processing chamber is rich in chlorinated methane gas and hydrogen gas. In a hydrogen-containing chlorinated methane-hydrogen mixed gas atmosphere, plasma is generated in a treatment chamber in the chlorinated methane-hydrogen mixed gas atmosphere, and the transparent conductive film adhering to the inside of the processing chamber is removed. The method for cleaning a transparent electrode film according to the first or second aspect of the invention, wherein a mixing ratio of the chlorinated methane gas to the hydrogen gas is 10 times or more of hydrogen gas added to the chlorinated methane gas.