JPH06163485A - Removing method of residual halogen inside reaction furnace for glow discharge film formation - Google Patents

Abstract

PURPOSE:To enable the reliability upon the film formation characteristics to be enhanced further enabling the corrosion inside a reaction furnace to be avoided for making the longevity of the furnace feasible, by a method wherein He gas plasma is generated after a specified cleaning is conducted and a specified gas is passed through a reaction furnace with a heated heater. CONSTITUTION:A film forming gas is led into a reaction furnace 1 wherein a substrate 10 for film formation and a heater 3 to set up a specific temperature are provided and then glow discharge is initiated inside the reaction furnace 1 to form an amorphous silicon base film on the substrate 10. Next, an etching gas containing halogen element is led into the reaction furnace 1 after taking out the film forming substrate 10 to perform the cleaning step and then air or an inert gas or hydrogen gas is passed through the reaction furnace 1 in the heating state of a heater 3. Finally, He gas is led into the reaction furnace 1 in the heating state of the heater 3 simulatneously producing plasma by the He gas to remove any resisdual halogen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention removes halogens remaining in a reaction furnace for film formation or etching to improve the reliability of film formation characteristics and prevents corrosion inside the reaction furnace, thereby prolonging the life of the reaction furnace. The present invention relates to a method for removing residual halogen in a reaction furnace for glow discharge film formation, which is capable of achieving high temperature.

[0002]

2. Description of the Related Art When an amorphous silicon film is formed by a glow discharge decomposition method, the discharge electrode plate and other insides of the reaction furnace are powdered as the film forming raw material silane gas is decomposed. Polluted by. Such a powder is formed by using the same glow discharge decomposition apparatus as the following amorphous silicon film (hereinafter, amorphous silicon is referred to as aS
When a film is abbreviated as i), it is taken in during film formation to cause a film formation defect, and the characteristic deterioration occurs in the defect portion.

In order to solve such a problem, a-Si
A fluorine-based etching gas such as CF ₄ gas, SF ₆ gas, ClF ₃ gas, and NF ₃ gas is introduced into the reaction furnace of the glow discharge decomposition apparatus on which a film is formed, and plasma is generated if necessary, and The powder is gasified and removed by etching accompanying the above.

However, when such a fluorine-based etching gas is used, the above gas etching cleaning can be performed, but on the other hand, there is a problem that the fluorine remains inside the reaction furnace. .

In order to solve such a problem, there has been proposed a fluorine removing method of removing molecular fluorine by flowing hydrogen in a molecular state after the gas etching cleaning (see JP-A-1-152274).

Further, a method for removing fluorine has been proposed in which a fluorine-containing compound gas, which is at least one of silane, phosphine, arsine, diborane, ammonia and lower paraffin hydrocarbons in a molecular state, is flowed to remove fluorine. 2-190472).

However, various experiments have revealed that the above proposed gas etching cleaning and fluorine removal methods still do not remove fluorine to a satisfactory degree.

Therefore, an object of the present invention is to further improve the reliability of film forming characteristics, and further, to prevent corrosion inside the reaction furnace and to extend the life of the reaction furnace. A method for removing residual halogen inside a furnace is provided.

[0009]

The method for removing residual halogen in a glow discharge film forming reactor according to the present invention comprises a substrate for film formation and a heater for setting the substrate at a predetermined temperature. The gas for a-Si film formation is introduced into the reaction furnace, and the glow discharge is generated inside the reaction furnace.
An a-Si-based film is formed on the substrate, the film-forming substrate is taken out of the reaction furnace, and an etching gas containing a halogen element is introduced into the reaction furnace for cleaning.
Next, the heater allows air or an inert gas or hydrogen gas to pass through the inside of the reaction furnace in the heated state, after which the heater introduces helium gas into the reaction furnace in the heated state, and It is characterized in that plasma is generated to remove residual halogen.

[0010]

The heater for heating the film-forming substrate is provided inside the reaction furnace of the glow discharge decomposition apparatus on which the a-Si film is formed. The gas etching cleaning is performed without heating by the heater. As a result, the heater surface is not corroded by the gas, and the life of the heater can be remarkably extended. However, the subsequent fluorine removal is also performed with the heater still attached, but it was found that some fluorine still remained in this heater even after the fluorine removal was performed by the already proposed fluorine removal method. . The presence of such residual fluorine causes the heater to be about 300 to 4 when forming the a-Si film.
It was found that fluorine was released under the high energy state of the heater since the temperature was raised to 00 ° C.

Therefore, according to the method for removing residual halogen in the glow discharge film forming reaction furnace having the above-described structure, based on the above knowledge, after the etching gas containing a halogen element is introduced into the reaction furnace and cleaning is performed, In the removal of residual halogen, the heater passes air or an inert gas or hydrogen gas into the heated reaction furnace, and then the heater introduces helium gas into the heated reaction furnace and the reaction furnace The residual halogen is removed by generating a plasma with helium gas inside. This removes the halogen adhering to the heater and eliminates the halogen emission due to the temperature rise of the heater in the next film formation. As a result, high quality a
-Form a Si film.

Further, the present inventor confirmed the following points through repeated experiments.

According to the present invention, it is preferable that the substrate temperature is higher than the substrate temperature at the time of film formation in purging or helium plasma in which the heater is heated. For example, it is preferable to set the temperature to 280 to 330 ° C. compared to the substrate temperature 280 ° C. at the time of film formation. Moreover, in order to promote the release of halogen from the glow discharge decomposition electrode plate and the side wall of the reaction furnace, it is advisable to heat them. If it is an electrode plate for glow discharge decomposition,
It may be set to 150 to 190 ° C. If it is the side wall of the reaction furnace, it may be set to 80 to 120 ° C.

Of the air, the inert gas or the hydrogen gas that is passed through the reaction furnace, the inert gas is particularly preferable because it does not contain water.

Then, when these gases are introduced into the reactor in which the heater is heated, the temperature rise and the temperature rise time in the gas purge should be 30 minutes or more,
As a result, halogen is released.

Further, when helium gas is introduced into the reaction furnace in which the heater is heated and plasma is generated in the reaction furnace by the helium gas to remove the residual halogen, the halogen is largely released in 40 minutes. Since it decays, the time required is 60 minutes or more.
The pressure of this plasma may be 10 to 40 mTorr, preferably about 20 mTorr. The high frequency power applied to it is preferably 300 to 700 W, and more preferably 500 W or more.

[0017]

EXAMPLES The present invention will be described in detail below with reference to a glow discharge decomposition apparatus for producing an a-Si photosensitive drum as an example.

[Glow Discharge Decomposing Device] FIG. 1 shows a glow discharge decomposing device, in which 1 is a cylindrical metal reaction furnace,
Reference numeral 2 is a cylindrical conductive substrate support for mounting a photosensitive drum, 3 is a substrate heating heater, and 4 is a cylindrical glow discharge electrode plate used for film formation of a-Si. A gas outlet 5 is formed in the
Is a gas inlet for introducing gas into the reaction furnace, 7 is a gas outlet for exhausting the residual gas of the gas exposed to glow discharge, and 8 is the substrate support 2 and the electrode plate for glow discharge. A high frequency power source for generating glow discharge between 4 and 9 is an exhaust pump. Further, the reactor 1 has a cylindrical body 1a.
, A lid 1b and a bottom 1c, and an insulating ring 1d is provided between the cylinder 1a and the lid 1b, and between the cylinder 1a and the bottom 1c. As a result, one terminal of the high-frequency power source 8 is electrically connected to the glow discharge electrode plate 4 through the cylindrical body 1a, and the other terminal is electrically connected to the substrate support 2 through the bottom body 1c.

Using this glow discharge decomposition apparatus, a-Si
In the case of producing a photoconductor drum, the drum-shaped substrate 10 for a-Si film formation is mounted on the substrate support 2, and a-Si generation gas is introduced into the reaction furnace through the gas introduction port 6. Gas is ejected to the surface of the substrate through the gas ejection port 5, the substrate is set to a desired temperature by the heater 3, and a glow discharge is generated between the substrate support 2 and the electrode plate 4, whereby the substrate 10 An a-Si film can be formed on the peripheral surface of.

The film forming conditions of this embodiment are as shown in Table 1. In this case, the temperature of the cylindrical body 1a of the reaction furnace 1 was about 80 ° C, and the temperature of the electrode plate 4 was about 150 ° C.

[0021]

[Table 1]

Example 1 When the a-Si photosensitive drum was manufactured as described above, contaminants adhered to the inside of the electrode plate 4 and the reaction furnace.

Therefore, a conductive dummy substrate made of aluminum metal having substantially the same shape as the substrate 10 is mounted on the substrate support 2, then ClF ₃ gas is introduced into the reaction furnace through the gas introduction port 6, and the gas injection port 5 is introduced. The gas is ejected toward the dummy substrate through the gas, and the gas is filled in the reaction furnace, whereby gas etching is performed and the contaminant is gasified. The conditions of this gas etching are as shown in Table 2.

[0024]

[Table 2]

Next, the heater 3 is set to about 300.degree. C., a heater is further provided on the cylindrical body 1a of the reaction furnace 1 and the electrode plate 4, and the respective set temperatures are set to about 100.degree.
The temperature was raised to 0 ° C. Then, purging was performed under the following conditions.

First, nitrogen (N ₂ ) gas is introduced into the reaction furnace through the gas introduction port 6, and is ejected toward the dummy substrate through the gas ejection port 5 to fill the reaction furnace with the gas. Then, the gas is discharged from the gas discharge port 7. The N ₂ gas inflow condition is a flow rate of 500 sccm and a pressure of 1 Torr.
It was flushed with r and was continuously purged for about 30 minutes. Next, the process of performing vacuuming to the ultimate vacuum and filling the reaction furnace with N ₂ gas until the pressure reaches 500 Torr is repeated three times.

After that, vacuuming is performed up to the ultimate vacuum while continuing to raise the temperature, and helium (He) gas is introduced into the reaction furnace under the conditions of Table 3, and plasma generated by helium gas is introduced into the reaction furnace. Raised.

[0028]

[Table 3]

Next, using the glow discharge decomposition apparatus in which the gas etching and the fluorine removal were performed as described above, the a-Si photosensitive drum was re-produced under the same film forming conditions as above. Then, when the amount of fluorine in the film of the a-Si photosensitive drum was measured, it was 0.1 ppm or less. The amount of fluorine was determined by SIMS analysis method using a secondary ion mass spectrometer.

The amount of fluorine was measured by a method in which a port was provided at the gas outlet 7 and the exhaust gas was evacuated into the Q-Mass apparatus to detect the peak of HF gas. It was Furthermore, there was no reaction when measured using an HF detector tube. Moreover, when the amount of fluorine in the constituent members of the reaction furnace was measured using Ponal Kit F manufactured by Wako Pure Chemical Industries, Ltd., it was 0.5 ppm.

[Example 2] In this example, in performing the same gas etching and fluorine removal as in [Example 1], helium gas was not introduced into the reaction furnace to generate plasma thereof. Took all the same steps.

Using the glow discharge decomposition apparatus from which fluorine has been removed, an a-Si photoconductor drum is produced again under the same film forming conditions as above, and the amount of fluorine in the film of the a-Si photoconductor drum is changed. Was 2 ppm or less.

The peak of the amount of fluorine by the Q-Mass apparatus was 0.20, and when measured using an HF detector tube, it was 0.1 ppm. Moreover,
When the amount of fluorine in the constituent members of the reaction furnace was measured using Ponard Kit F, it was 5 ppm.

Example 3 In removing fluorine in the present example, an a-Si photosensitive drum was prepared under the same conditions except that the heater 3 was not heated, and the a-Si photosensitive drum was prepared. When the amount of fluorine in the film of No. 2 was measured, it was periodically changed in the film direction, and the maximum value was 350 ppm and the minimum value was 180 ppm. Such a periodic fluctuation is caused by turning on the heater 3.
From the experimental results, it is considered that the fluorine adsorbed on the surface of the heater 3 is released by the temperature rise of the heater 3 during film formation and is taken into the film.

Further, the present inventor obtained the same result in the present embodiment even when the gas etching cleaning was performed using CF ₄ , SF ₆ , NF ₃ , F ₂ or the like as the fluorine-based etching gas.

Further, in the above embodiment, N ₂ gas was introduced to remove fluorine, but the same result was obtained by using an inert gas such as Ar or air or hydrogen gas.

[0037]

As described above, according to the method for removing residual halogen in the glow discharge film forming reactor of the present invention, a-Si
The film-forming substrate on which the system film has been formed is taken out of the reaction furnace,
After that, an etching gas containing a halogen element is introduced into the reaction furnace for cleaning, and then the heater is allowed to pass air or an inert gas or hydrogen gas into the heated reaction furnace, after which the heater is heated. The helium gas is introduced into the reaction furnace and the plasma is generated by the helium gas inside the reaction furnace to remove the residual halogen. As a result, the halogen attached to the heater was removed, and in the next film formation, the halogen was not released due to the temperature rise of the heater, and as a result, a high-quality a-Si film containing no halogen element could be formed. .

[Brief description of drawings]

FIG. 1 is a schematic view of a glow discharge decomposition apparatus in an example.

[Explanation of symbols]

 1 Metal Reaction Furnace 1a Cylindrical Body 1b Lid 1d Ring 3 Substrate Heating Heater 4 Glow Discharge Electrode Plate 8 High Frequency Power Supply

Claims (1)

[Claims] 1. An amorphous silicon film-forming gas is introduced into a reaction furnace provided with a film-forming substrate and a heater for setting the substrate to a predetermined temperature, and glow discharge is also introduced into the reaction furnace. To form an amorphous silicon film on the substrate, and after removing the film-forming substrate from the inside of the reaction furnace, an etching gas containing a halogen element is introduced into the inside of the reaction furnace to perform cleaning. The heater allows air or an inert gas or hydrogen gas to pass through the inside of the reactor in a heated state, and then the heater introduces helium gas into the inside of the reactor in a heated state. A method for removing residual halogen in a reactor for glow discharge film formation, which comprises removing residual halogen by generating plasma.