JPS5955343A - Plasma cvd device - Google Patents

Abstract

PURPOSE:To produce a CVD film of uniform thickness and characteristics by providing plural gas introducing systems which can control independently the introducing rate of a gaseous mixture and evacuation system which can control independently the suction rate of the gase. CONSTITUTION:A photosensitive drum of amorphous silicon is manufactured after the flow rates are empirically verified by mass flow controllers 23a-23d for gaseous mixtures and conductance valves 27a-27d for controlling evacuation rates in such a way that the film forming speed is made uniform in a plasma CVD device having an electrode 25 provided with plural gas blow-out ports and an electrode 26 provided with plural gas suction ports. As a result, the variance in the film thickness is 1.05 ratio between the max. value and the min. value when an average film thickness is 22mu, and the extremely uniform film thickness is obtd. as compared with the prior art. The film has 400+ or -15V electrifying potential thus exhibiting uniform characteristics.

Description

Detailed Description of the Invention The present invention has a plurality of gas introduction systems that can independently control the amount of mixed gas introduced, and an exhaust system that can independently control the amount of gas suction. The present invention relates to a plasma CVD apparatus that aims for uniformity of characteristics.

In recent years, with a focus on amorphous silicon, plasma OVD
Research into thin film devices using this method has become active.

FIG. 1 is a block diagram showing an example of a conventional Amol 7 Asun Recon photoreceptor manufacturing apparatus. In the same figure, 10
11 to 10 g are hydrogen, argon, methane, diborane, and monosilane cylinders, respectively. Also 11α~11
d is a valve, 12a to 12g are mass flow controllers for adjusting gas flow rate, 13 is a mixed gas introduction pipe, 14 is an electrode equipped with a gas outlet, 15 is a drum, 16 is a vacuum chamber, 17 is a shaft, and 18 is a motor , 19 is a pump.

The electrode 14 has a shape in which two cylindrical surfaces with different radii of curvature overlap, and the side surfaces are tightly covered.

Additionally, there are numerous gas blow holes on the side facing the drum. A plurality of gas introduction tubes are attached to the opposite cylindrical surface, and gas is introduced from the tubes into the space surrounded by the two cylindrical surfaces and the side surface, and is discharged through the holes to the drum side.

A method of manufacturing an amorphous silicon film for a photosensitive drum using the apparatus shown in FIG. 1 will be described.

The inside of the vacuum chamber 16 is pumped by the pump 19.
The temperature of the drum is maintained at 230 to 250°C while exhausting to 10-3 Torr. Heating can be done by placing the cylindrical drum in a cylindrical drum holder with a built-in heater and heating it from inside, or by infrared heating. Use.

When the temperature of the drum reaches a predetermined temperature, hydrogen, argon, methane, diborane, and monolan gases are flown into the vacuum chamber as a mixed gas by controlling the flow rates thereof by the mass 70-controller. The flow rate ratio of each gas has a large relationship with the photosensitive characteristics of the photosensitive drum, and the optimum value also depends on the high frequency power and the temperature of the drum during thin film deposition. To give one example, the high frequency power is 500W.
.

When the temperature of the drum is 230°C, the flow rate ratio of each gas is 10 for hydrogen, 04 for argon, 05 for methane, and 1 x 104 for diborane. Monosilane is 1.0.

Furthermore, the gas flow rate is adjusted so that the pressure inside the vacuum chamber when the gas is flowing becomes I Torr.

When a high frequency discharge is generated between the electrode 14 and the drum 15 in this state, the introduced gas is decomposed and an amorphous silicon film is completely formed on the surface of the drum 15. In order to obtain uniformity of film thickness, the drum is rotated by a motor 18 through a shaft 17. The rotation speed is about 10 revolutions per minute.

Although it is possible to produce an amorphous silicon photosensitive drum using such an apparatus, the performance cannot be said to be sufficient. The problem is that the film thickness cannot be sufficiently uniform.

That is, it has the following drawbacks.

■Mixed gas (H2+ A r OH4, B2H6.

S:LH,) is introduced into the \rt, pole 14 from a plurality of introduction pipes, but since each introduction pipe does not have a flow rate control function, the gas flow rate of each introduction pipe differs due to slight differences in impedance. Therefore, variations occur in the thickness of the amorphous silicon film formed on the drum.

(2) Since the exhaust port of the vacuum chamber is located at the bottom, even if the same amount of gas is blown out from the gas outlet of the electrode 14, the amount of gas that comes into contact with the lower part of the drum will be larger. Therefore, the film thickness becomes thicker at the bottom of the drum.

When the film thickness varies, the charging potential naturally varies, causing variations in copying sensitivity, which becomes a major problem.

Even in a photosensitive drum manufactured under optimal conditions using a conventional apparatus, the ratio between the maximum value and the minimum value of the film thickness is 1.1 to 1.2.

The present invention eliminates these drawbacks, and its purpose is to improve the uniformity of the thickness and properties of a film obtained by plasma OVD. Yet another purpose! The purpose is to increase the film formation speed by using both the electrode and the gas blowing part.

FIG. 2 is a block diagram of an embodiment of the invention.

As an example, an apparatus for manufacturing an amorphous silicon photosensitive drum will be described. In Figure 2, 'lOa ~ 20
g are hydrogen, argon, methane, diborane, and monosilane gas cylinders, 21a to 21g are pulp, 22
α~22g are hydrogen and argon gas mass flow controllers, respectively, 23α~26d are mixed gas mass flow controllers, 24a~24d are mixed gas introduction pipes,
25 is an electrode having a gas outlet, 26 is an electrode having a gas exhaust port, 27a to 27d are conductance valves for adjusting the exhaust amount, 28 is a pump, and 29 is a vacuum chamber.

FIG. 3 shows an enlarged view of the electrodes 25 and 26 in FIG.

In the figure, 31 is an outer cylindrical surface of the electrode having a gas outlet, 32 is an inner cylindrical surface, and 63 is a gas outlet. Further, 35 is an outer cylindrical surface of the electrode having a gas exhaust port, 36 is an inner cylindrical surface, and 37 is a gas exhaust port. Further, 38 a N38 d is a mixed gas introduction pipe, and 3917 to 39 d are exhaust pipes.

Using the apparatus shown in FIG. 2, mass flow controllers 2311 to 23d and conductance valves 27α to 27
After experimentally confirming the flow rate to make the film formation speed uniform in step d, we fabricated an amorphous silicon photosensitive drum.As a result, the variation in film thickness was as follows: When the average film thickness was 22 μm, the ratio of the maximum value to the minimum value was 105, and a much more uniform product was obtained compared to the conventional method. Furthermore, the film exhibited uniform characteristics with a charging potential of 400±15V.

Furthermore, since the present invention uses an electrode that serves both as a gas blowout and gas suction port, compared to an electrode placed outside the chamber, the electrode is closer to the drum surface and the plasma density is higher, resulting in a film formation speed of 7. It was also found that it was very large, ~8 μm/).

Although the present invention has been described with respect to a cylindrical electrode, a planar electrode as shown in FIG. 4 has exactly the same effect in terms of measuring the uniformity of the film.

In Fig. 4, 40 is an electrode/gas blowing part, 41a to 41
c is a drum, and 42a to 42d are mixed gas introduction pipes.

In this way, the present invention applies not only to photosensitive drums but also to amorphous silicon devices, such as 5102, Si3N,
This has a great effect on measuring the uniformity of amorphous films such as.

[Brief explanation of the drawing]

Figure 1 shows a conventional amorphous silicon photoreceptor manufacturing apparatus, Figure 2 is a block diagram of the present invention, Figure 3 is an enlarged view of electrodes 25 and 26 in Figure 2, and Figure 4 is a planar electrode. It is a figure showing a structure. 20α~20g...Gas cylinder 21a~21g
...Valves 22α to 22e...Mass flow controller 2
5a to 23d...Mass flow controller 24
α~24d...Mixed gas introduction pipe 25...
・・・・・・・・・・・・・・・Gas outlet 26
・・・・・・・・・・・・・・・・・・Gas exhaust ports 27a to 27d・・・Conductance valve 2
8・・・・・・・・・・・・・・・・・・・・・Pump 29・・・・・・・・・・・・・・・・・・・・・Vacuum chamber and above Applicant Figure 1: Tsutomu Mogami, Patent Attorney, Suwa Seikosha Co., Ltd.

Claims (1)

[Scope of Claims] 1) In a plasma CVD apparatus having a plurality of gas outlets and a plurality of gas inlets, a plurality of mixed gas introduction systems capable of independently controlling the amount of gas introduced, and an independent gas exhaust system are provided. A plasma CVD apparatus having an exhaust system that can control the amount. 2) The plasma CVD apparatus according to claim 1, wherein at least one of the surface having the gas outlet and the surface having the gas exhaust port also serves as a discharge electrode.