JPS6117151A - Plasma cvd device - Google Patents

Abstract

PURPOSE:To eliminate the stagnancy of gas to prevent a fine powder or peeled pieces from being caught into a film on a substrate, by providing exhaust ports near both ends of the substrate and an electrode. CONSTITUTION:The first exhaust port 6 is provided under lower parts of both of a cylindrical substrate 1 and a cylindrical electrode 2 which is arranged with the same axis as the substrate 1, and the second exhaust port 6' is provided on their upper end parts. Exhaust ports 6 and 6' are connected to a common vacuum pump 7 through exhaust control valves 9 and 9' respectively. Gas passes a gas chamber 3 from an introducing entrance 4 and is mixed and dispersed uniformly and is blown to a discharging area between the electrode 2 and the substrate 1 and is discharged from upper and lower end parts through exhaust ports 6 and 6' as shown by arrows. Thus, the stagnancy of gas near end parts of the cylindrical substrate is eliminated to prevent the occurrence of fine powder.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a plasma CV method for depositing a film on a cylindrical substrate.
Regarding D device.

(Prior Art) Plasma CVD technology is a film forming technology characterized by being able to grow thin films at relatively low temperatures. In plasma CVD technology, by placing a reactive gas in a discharge plasma state, for example, by high-frequency radiation, the chemical bonds of the reactive gas are decomposed at a low temperature, and activated particles are created. A CVD film is formed by the reaction between the particles.

The properties of plasma CVD films are influenced by numerous factors. These factors include production temperature, production gas ratio, production pressure, electrode structure, reaction vessel structure, pumping speed, production RF power, and R
There are F frequency, plasma generation method, etc. Therefore, many factors must be controlled in order to form a plasma CVD film.

Plasma CVD technology is used to form films of various substances, and can also form films of amorphous silicon (a-8i), for example. a-8i is also suitable as an electrophotographic photoreceptor. When used as an electrophotographic photoreceptor, a
-8i film is relatively thick (2
0 to 50 μm) and must be formed uniformly.

FIG. 5 schematically shows an example of a conventional plasma CVD apparatus for A-8I. The substrate 1 made of an aluminum cylinder is
It is provided inside the cylindrical electrode 2 so as to be rotatable around its axis. The electrode 2 is composed of two cylindrical plates 2a and 2b that share the same axis as the substrate 1, and the gas chamber 3 is defined by these two cylindrical plates 2a and 2b. The outer cylindrical plate 2a is provided with an inlet 4 for introducing raw material gas from a gas supply device (not shown), while the inner cylindrical plate 2a is provided with an inlet 4 for introducing raw material gas from a gas supply device (not shown). 1) is provided with a large number of small supply ports (not shown) for introducing raw material gas into the internal space (discharge area) of this cylindrical plate 2b. The chamber (vacuum chamber) 5 consists of an electrode 2, an upper part 5a, and a lower part 5b.
b is insulated from the electrode 2.

The gas introduced into the chamber 5 from the above supply port is
A vacuum pump 7 is connected to the bottom of the chamber 5 through an exhaust port 6.
Exhausted by. RF power source 8 is connected to electrode 2 via inlet 4, while substrate 1 is grounded. Heaters (not shown) are attached to the substrate 1 and electrode 2, respectively, and connected to a heater power source.

A-8i film formation by plasma CVD is performed as follows. (Refer to Paschen's law or the start of a self-sustaining discharge).
The exhaust port 6 is provided only at the - location, usually at the lower end of the vacuum chamber. Therefore, the gas in the open discharge area between the substrate 1 and the electrode 2 flows out from the side near the exhaust port 6, but on the other hand, it is difficult to flow out from the side far from the exhaust port, and from the exhaust port of the substrate 1. Gas tends to stagnate near the far end (indicated by P in FIGS. 5 and 6). Moreover, due to the structure, a discharge concentration area occurs at the end of the substrate 1 and the electrode 2 due to a non-uniform electric field. This gas retention, combined with the concentration of discharge, tends to generate fine powder of (SiH2)n near the gas retention part P, and also tends to cause the film to peel off in the discharge concentration part. The generated flakes and fine powder are carried by the gas flow in the discharge region between the substrate 1 and the electrode 2, and are taken into the film on the substrate 1, deteriorating the film quality. This causes white spot noise. Furthermore, in the plasma CVD apparatus shown in FIG. 4 of Japanese Patent Application Laid-open No. 58-52650,
The exhaust ports are provided at approximately equal positions from the upper and lower ends of the substrate. Furthermore, in the plasma CVD apparatus disclosed in Japanese Unexamined Patent Publication No. 59-70760, two exhaust ports are similarly provided at approximately equal positions on the upper and lower ends of the substrate. The electrodes of the latter device have a complicated structure consisting of a gas chamber for introducing gas and a gas exhaust port, making it difficult to manufacture the electrodes.

The purpose of the present invention is to eliminate the accumulation of force near the edge of a cylindrical substrate in a plasma CVD apparatus, to suppress the generation of fine powder, and to eliminate the possibility of film peeling in areas where discharge is concentrated. The purpose is to prevent deterioration of film quality by promptly discharging film peeling pieces from the discharge area.

The present invention achieves this objective with a configuration different from the conventional example described above.

(Means for Solving the Problems) A plasma CVD apparatus according to the present invention includes a cylindrical electrode with both ends open and a cylindrical substrate rotatably provided inside the electrode with a common axis in a vacuum chamber. In a plasma CVD apparatus that discharges raw material gas from a number of openings provided on the inner circumferential surface of the electrode and forms a film on an opposing substrate, a vacuum chamber is installed near the openings at both ends of the cylindrical electrode. It is characterized by having an exhaust port from.

(Function) By providing exhaust ports near both ends of the substrate and the electrode, there is no gas retention area, and the gas flows from the discharge region toward both ends. Therefore, fine powder and peeled pieces are not incorporated into the film on the substrate.

(Example) Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The first embodiment shown in FIG. 1 is the same as the example shown in FIG. 5 except that two exhaust ports are provided. The first exhaust port 6 is provided below the lower end of both the cylindrical substrate 1 and the cylindrical electrode 2 having a common axis therewith, while the second exhaust port 6 is provided at the upper end. provided on the upper side of the section. Each exhaust port 6, 6' is connected to a common vacuum pump 7 via an exhaust control valve 9, 9', respectively. As shown by the arrows in FIG. 1, the gas is uniformly mixed and diffused from the inlet 4 through the gas chamber 3, and then blown onto the discharge area between the electrode 2 and the substrate 1, and then at the upper and lower ends. The air is exhausted from the air through exhaust ports 6 and 6, respectively.

The exhaust control valves 9, 9' adjust the flow rate of exhaust gas.

Unlike the conventional apparatus shown in FIG. 5, there is no accumulation of gas at the upper end of the chamber 5, and no fine powder is generated. Further, peeled pieces of the a Si film generated in the discharge concentrated area are carried by the gas flow to the outside of the discharge area. In this way, the occurrence of membrane quality abnormalities can be prevented.

The second embodiment shown in FIG. 2 is the same as the example shown in FIG. 6 except that two exhaust ports are provided. The first exhaust port 6 is provided below the lower end of both the cylindrical substrate 1 and the cylindrical electrode 2 having a common axis therewith, while the second exhaust port 6 is provided at the upper end. provided on the upper side of the section. The exhaust port 6 is connected to a vacuum pump 7 via an exhaust control valve 9, while the exhaust port 6' is connected to another vacuum pump 7' via an exhaust control valve 9'. In FIG. 2, gas flows as indicated by the arrows and no gas stagnation occurs.

The third embodiment shown in FIG. 3 corresponds to the first embodiment shown in FIG. 1 in which the substrate 1 and the electrode 2 are arranged horizontally. One exhaust port 6 is provided near the bottom of the right end of both the cylindrical substrate 1 and the electrode 2, and the other exhaust port 6 is symmetrically provided near the bottom of the left end. It will be done. Although not shown, the exhaust ports 6 and 6' are each connected to a vacuum pump via an exhaust control valve. In FIG. 3, gas flows as indicated by the arrows and no gas stagnation occurs.

The fourth embodiment shown in FIG. 4 corresponds to the second embodiment shown in FIG. 2 in which the substrate 1 and the electrode 2 are arranged horizontally. One exhaust port 6 is provided near the bottom of the right end of both the cylindrical substrate 1 and the electrode 2, and the other exhaust port 6 is symmetrically provided near the bottom of the left end. It will be done. Although not shown, the exhaust ports 6 and 6' are each connected to a vacuum pump via an exhaust control valve. In FIG. 4, the gas flows as shown by the arrow, and there is no stagnation of gas at all.

(Effects of the Invention) Gas stagnation near the end of the cylindrical substrate is eliminated. This prevents the generation of fine powder.

Peeled off pieces of the film caused by the concentration of discharge are carried along with the gas flow and are not incorporated into the film on the substrate.

As a result, the film formation properties at both ends of the film on the substrate are improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 to 4 are schematic cross-sectional views of embodiments of the invention. Figures 5 and 6 respectively show conventional plasma CVD
FIG. 2 is a schematic cross-sectional view of the device. 1... Cylindrical substrate, 2... Cylindrical electrode, 3
...Gas chamber, 4...Inlet, 5...
Chamber, 6,6゛...Exhaust port, 7.7゛...Vacuum pump, End...RF power supply. Third cause 6' Figure 4 Figure 5

Claims (1)

[Claims] (1) A cylindrical electrode with open ends at both ends and a cylindrical substrate rotatably provided inside the electrode with a common axis are arranged in a vacuum chamber, and a large number of openings provided on the inner peripheral surface of the electrode are placed. A plasma CVD apparatus for emitting source gas to form a film on an opposing substrate, characterized in that exhaust ports from a vacuum chamber are provided near openings at both ends of the cylindrical electrode.