JPS62103370A - Apparatus for manufacturing electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To increase the speed of forming the film of amorphous silicon and to improve production efficiency by arraying permanent magnets to the outside periphery of a reaction vessel by alternating N poles and S poles over the entire periphery. CONSTITUTION:The bar magnets 3, 4 and 7 are formed like a cusp on the inside wall of the cylindrical reaction vessel 1 of a thin film forming device utilizing plasma for forming the amorphous silicon film by alternately arranging the N poles and S poles thereof around the vessel 1. The diffusion of the plasma to the inside wall is thereby shut out and the high-density plasma is formed in the state of floating the same from the wall of the vessel 1. The sticking of the amorphous silicon to the inside wall of the vessel 1 and the formation of the pulverized powder-like amorphous silicon are decreased by such constitution and the high production efficiency is obtd.; in addition, the speed of forming the amorphous silicon film is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an apparatus for producing an electrophotographic photoreceptor.

[Background of the invention]

Conventionally, in order to produce a hydrogenated amorphous silicon photoreceptor at high speed, a large amount of silicon hydride gas such as mono-7 run gas (SIH4) as the main raw material has been used and decomposed with high power.

However, since the gas utilization efficiency is at most 10%, most of the main raw material gas is either exhausted to the atmosphere or attached to the inner wall of the reaction tube, making this method extremely inefficient.

Conventional plasma CVD apparatuses are shown in FIGS. 9 to 11. In the case of FIG. 9 (this method is common), since the plasma is not controlled, the plasma spreads as shown in the figure and reaches the wall surface of the reaction vessel, so that an amorphous silicon film adheres to the wall surface. In the case of FIG. 10, by surrounding it with a mesh-like electrode, the spread of plasma is improved compared to the method shown in FIG. 9, but there is a lot of adhesion to this mesh-like electrode, and the actual manufacturing efficiency is not high. The method shown in Fig. 11, as shown in Japanese Patent Laid-Open Nos. 57-47710 and 57-45224, attempts to confine plasma in the entire center using a magnetic field formed by an electromagnet set on the outer wall of the reaction vessel. . Although this method is effective in confinement, the magnetic field becomes as shown in FIG. 11, making it easier for plasma to escape along the lines of magnetic force.

[Purpose of the invention]

The purpose of the present invention is to isolate the plasma from the wall surface of the reaction vessel and improve the plasma density by using an external magnetic field.
It is an object of the present invention to provide an electrophotographic photoreceptor manufacturing apparatus that is capable of high-speed deposition and has high manufacturing efficiency.

[Summary of the invention]

The basic points of this invention are narrowed down to the following two points. (1) Plasma confinement uses a magnetic field.

(2) To form the magnetic field, as shown in Figure 1, a rod-shaped N pole,
The south poles are arranged alternately to form a cup-like magnetic field on the inner wall of the container. Figure 2 shows the magnetic field when viewed from above the container.

By forming such a magnetic field distribution on the inner wall of the reaction vessel, diffusion of the plasma to the inner wall can be shut out, and the entire high-density plasma can be formed in a state floating from the wall.

[Embodiments of the invention]

The present invention will be explained in detail below.

Example 1 The apparatus shown in FIG. 1 was used for producing an amorphous silicon (a-8iiH) film. Rod-shaped permanent magnets 3, 4 and 7 are arranged around the cylindrical reaction vessel 1. The strength of this magnet at the inner wall of reaction vessel 1 is 10
00 Gauss, and 1 at 4-5 cm further inward.
It drops to 00 Gawasu. The magnetic field created by these magnets (see Figure 2) acts as a reflective barrier for charged particles and surrounds the plasma. A substrate 2 is fixed at the center of the reaction vessel 1 by a Holter internal heater (including a Holter internal heater), and is maintained at a predetermined temperature between 200 and 350° C. during film formation. At the bottom of the reaction vessel, a filament 5 for emitting thermionic electrons generates plasma by passing a current of 20 to 30 A, and an arc current of up to 1
It can generate up to 0A. Monosilane gas, the main raw material, is mixed with hydrogen or diborane gas as necessary and introduced through pipe 8, and unreacted gas is released into the atmosphere from exhaust port 9 via a mechanical pump, rotary pump, tari pump, and waste gas treatment tank. be done.

First, the inside of the reaction vessel is evacuated to IXt 0-a Torr, and then a conductor such as a substrate CAt is heated to 250°C.

After that, monosilane gas was introduced into the reaction tank and the temperature was set at 1 mTorr.
r, and a current of 3OA is applied to the filament 5 to excite plasma. On the other hand, the substrate has a bias voltage of 6 to 1200
Apply v. After one-time open film formation in this manner, the substrate is cooled to 20°C.

The film formation rate under these conditions was 10 μm/h.

Bias voltage 1-300. The film formation speed when set to -400v was 16.5 and 20 μm/h. These results are shown in FIG.

Example 2 In the same manner as in Example 1, mono7/gas was heated to 2 mTor.
r was introduced. A current of 30 A is passed through the filament 5 to excite plasma. On the other hand, a bias voltage of 6 to 200 V is applied to the substrate. After forming a film in this manner for one hour, the entire substrate was cooled to 20°C. The film formation rate under these conditions was 17 μm/h. Similarly, when the bias voltage is -300y and -400V, the film forming rate is 25°35 μm/h. A summary is shown in Figure 4.

In both Examples 1 and 2, the amorphous silicon film adhering to the inner wall of the reaction vessel is concentrated at the center/portion of the N or S pole magnet (explained in Figure 2, the source of the magnetic field lines), and the degree of plasma convergence is It is good, and there is only a trace amount of powdered amorphous silicon produced when monosilane gas decomposes.

Example 3 For comparison with Examples 1 and 2, a film was formed by removing the permanent magnet attached to the outer periphery of the reaction vessel.

The monosilane gas introduced into the reaction vessel was at 1 mTorr. A current of 3OA is applied to the filament 5 to excite plasma. On the other hand, the substrate KH bias voltage is 6 to 200V.
Apply it. After forming a film in this manner for one hour, the substrate is cooled to 20°C. The film formation rate under these conditions is 5 μm
/h. Similarly, increase the bias voltage to -300.
, -400V, the film formation rate is 7.10μm/h
It is.

These results are summarized in FIG. In the absence of this permanent magnet, an amorphous silicon film would adhere to the entire circumference of the inner wall of the reaction vessel, and a large amount of powdered amorphous silicon would be produced.

Comparing Examples 1 and 2 and Example 3 above, it can be seen that plasma confinement using a magnetic field is effective (that is, the film formation rate is faster when a magnetic field is provided, and the generation of fine powder and the inner wall of the container are Example 4 In Examples 1 and 2, thermoelectrons emitted from the filament were used for plasma excitation, but the filament life was short, about 100 hours. To compensate for this drawback, plasma is excited using a high frequency power source (frequency: 13.56 MHz). Figure 6 shows the apparatus. (The difference from Figure 1 is that a high-frequency coil is used for 15 and the bias voltage is omitted.) This coil can have the same effect even if it is attached to the outer periphery of the reaction vessel. Furthermore, the same effect can be expected even if opposing electrode plates are used as shown in FIG.

First, as in the above example, 6txto-'To in the reaction vessel
After evacuation to r r, the substrate is heated to 250°C.

After that, monosilane gas was introduced into the reaction tank and the temperature was set at 1 mTorr.
Let r be the fossa frequency! Input 50W between the poles and start broadcasting TV. On the other hand, the board is kept electrically grounded. After forming a film in this manner for one hour, the substrate is cooled to 't20'c. The film formation rate under these conditions was 8 μm/h. The reason why no bias voltage is used, unlike the previous embodiment, is that the same condition as when a bias voltage (self-bias) is applied to one of the high-frequency electrodes is created due to the accumulation effect of charged particles. Therefore, in order to improve the film formation speed, the high frequency output was increased to 100, 150, and 300 W to form a film. The film formation rate at this time was 15.19
．． It was 37 μm/h. The results are summarized in Figure 8.

In this example as well, there is little adhesion of the amorphous silicon film to the tube wall and electrodes.

In addition, - Examples of the method of plasma excitation in this method include a method using microwaves, a method of exciting with ultraviolet light, far ultraviolet light, etc.

・If the bias voltage is positive, it can become an etching device.

・Can be used to contain plasma in sputtering equipment.

〔Effect of the invention〕

According to the present invention, the deposition rate of the amorphous silicon film can be more than twice as fast as that of the conventional method, and the adhesion of amorphous silicon to the inner wall of the reaction vessel and the amount of amorphous silicon in the form of fine powder can be reduced. It is possible to provide amorphous silicon manufacturing equipment with high manufacturing efficiency.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a magnetic field superimposed type plasma CVD device according to an embodiment of the Naoko photographic photoconductor cleaving device of the present invention, and FIG.
3, 4, and 5 are explanatory diagrams of the relationship between bias voltage and film-forming rate in the case of manufacturing using the apparatus shown in FIG. FIG. 8 is a cross-sectional view of a magnetic field superimposition type high frequency plasma CVD device of another embodiment of the electrophotographic photoreceptor explosion device, and FIG. 10 is a cross-sectional view of a conventional plasma CVD apparatus using mesh electrodes, and FIG. 11 is a cross-sectional view of a conventional magnetic field superimposition type high-frequency plasma CVD apparatus. DESCRIPTION OF SYMBOLS 1... Reaction container, 2... Substrate, 3.4... Permanent magnet, 5... Thermionic source (filament), 6... Bias voltage.

Claims (1)

[Claims] 1. An electrophotographic photoreceptor manufacturing apparatus that uses plasma to form a thin film, and is characterized in that rows of permanent magnets are arranged around the outer periphery of a reaction container, alternating with N poles and S poles.