JPH0250195B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a film forming method and a film forming apparatus for forming an amorphous Si layer on the surface of a photoreceptor by, for example, glow discharge.

Technical background and problems of the invention Generally, in electrophotographic devices, Se,
Photoreceptors such as ZnO and OPC are used, but Se photoreceptors have a low glass transition point of 42 to 40℃, so
When the temperature inside the device increases rapidly, such as in summer, the surface potential decreases, resulting in a decrease in image density, and ZnO photoreceptors also have the disadvantage of shortened moisture resistance and life.

Therefore, a photoreceptor made of gold-dot amorphous Si (a-Si) has attracted attention. This a-Si photoreceptor is molded, for example, as shown in FIGS. 1 and 2. That is, a mixed gas of SiH ₄ gas and about 10 ppm B ₂ H ₆ is introduced into the chamber 1, which is evacuated to 10 ^-5 Torr or more, through the introduction pipe 2, and the pressure is reduced to 0.1.
The temperature of the aluminum drum substrate 3 is set to 250° C. by the heater 5, and power is supplied from the RF power supply source 4 to the electrode 9 to start glow discharge. As a result, SiH ₄ and B ₂ H ₆ move in the direction of the arrow and form radicals such as Si-H, Si-H ₂ and Si-H ₃ by glow discharge within the chamber 1, and the aluminum drum substrate 3 to form an amorphous Si layer. On the other hand, the SiH ₄ and B ₂ H ₆ gases in the chamber 1 are exhausted through the mechanical booster pump 7 and the rotary pump 8, and are disposed of through a combustion tower (not shown).
Note that the aluminum drum substrate 3 is rotated as shown in FIG. 2, and there is no uneven deposition in the circumferential direction.

However, in the past, SiH ₄ , B ₂ H ₆
As can be seen from the gas flow, the exhaust is done from below, so the aluminum drum board 3 is
The density of the gas is different at the bottom. For this reason, the matching state of the glow discharge changes, and the film thickness of the a-Si layer 6 on the aluminum drum substrate 3 after deposition is different at the top, middle, and bottom of the drum substrate 3, resulting in an inconvenient nonuniformity. Ta.

Purpose of the Invention The present invention has been made focusing on the above circumstances,
The purpose is to provide a film forming method and a film forming apparatus that can form an amorphous Si layer with a uniform thickness.

Summary of the Invention The present invention separates a cylindrical electrode into a plurality of parts along its axis, connects a power source to each of these separated electrodes individually, and constantly supplies a constant amount of current from each power source to each separated electrode. It was designed to be supplied.

Embodiment of the Invention Hereinafter, an embodiment of the present invention will be described based on FIGS. 3 and 4. In the figure, reference numeral 11 denotes a chamber, and within this chamber 11 is rotatably housed an aluminum drum substrate 12 serving as a membrane support. A heater 13 is inserted into the drum substrate 12, and the outer periphery of the drum substrate 12 is surrounded by a cylindrical electrode 14. This electrode 14 is divided into upper, middle, and lower parts in the axial direction, and each of these separated electrodes 14a, 14b, 1
Insulating tubes 15, 16, and 17 are interposed between 4c. Separate RF power supplies P ₁ , P ₂ and P ₃ are connected to these separation electrodes 14a, 14b and 14c, respectively. In addition, the separation electrodes 14a, 14b, 1
The amount of discharge current supplied to 4c is measured by the ammeter 18,1
9 and 20. Furthermore, the above-mentioned ammeters 18, 19, 20 and the above-mentioned
RF power supplies P ₁ , P ₂ , P ₃ are feedback circuit 18
Connected by turning a, 19b, 20c, ammeter 1
When the current flowing through terminals 8, 19, and 20 differs from a predetermined value, a signal is sent to the RE power supplies P ₁ , P ₂ , and P ₃ to control the current so that a predetermined amount of current flows at all times. There is.

Furthermore, an exhaust pipe 2 is provided at the bottom of the chamber 11.
3 is connected to the exhaust pipe 23, and a mechanical booster pump 21 and a rotary pump 22 are attached to this exhaust pipe 23.

Further, the separation electrodes 14a, 14b, 14c have a gas passage 24 inside, and a large number of ejection holes 25 are bored in the inner peripheral surface. Furthermore, a gas introduction pipe 26 is connected to the inner bottom of the chamber 11 .

However, during film formation, the vacuum chamber 11 is
A vacuum of 10 ^-6 Torr is drawn and electricity is applied to the heater 13 to heat the conductive drum substrate 12 to 250°C. In addition, SiH ₄ gas is introduced from the gas introduction pipe 26.
A 300 _SCCM is introduced and SiH ₄ gas is sprayed from the gas spout 25 toward the surface of the drum substrate 12.
The gas is exhausted by an exhaust system of a mechanical booster pump 21 and a rotary pump 22. An exhaust valve (not shown) is adjusted so that the SiH ₄ gas pressure in the vacuum container 11 is 1.0 Torr. Further, in order to ensure uniformity of the a-SiH film in the circumferential direction, the drum substrate 12 is rotated by a motor (not shown).

From this state, turn on the radio frequency power (RFPower) power supplies P ₁ , P ₂ , and P ₃ and set the power of all power supplies P ₁ , P ₂ , and P ₃ to 500W.

Generally, SiH ₄ plasma discharge is performed at the exhaust port (downward).
Ammeters 18, 19,
The value monitored by 20 becomes larger as it moves downward. Therefore, using circuits 18a, 19b, and 20c that feed back these values _, the RF power is reset to a larger power of 550W for power supply _P1 and a smaller power of 450W for power supply _P3 , based on the 500W of power supply P2 in the middle. Ru.

After about 3 hours of film formation, a-
A SiH photoresist film 12a is deposited to a thickness of approximately 25 μm, and during this time, feedback circuits 18a, 19b, and 20c are used to control the upper, middle, and lower portions as the plasma situation changes.
The power setting values of the RF power sources P ₁ , P ₂ , and P ₃ are reset each time.

The photoreceptor film thickness on the a-Si photoreceptor drum formed in this way is 25μ on the upper, middle and lower surfaces of the drum substrate 12.
m±0.5 μm.

On the other hand, in the a-Si photoreceptor drum shown in the conventional a-Si photoreceptor device shown in FIG. The thickness of the membrane is 21μm at the top and about 21μm at the middle.
It was extremely non-uniform, measuring 25 μm and 28 μm at the bottom.

In the above embodiment, the electrode 14 is divided into three parts, but the present invention is not limited to this. If the electrode 14 is further divided into three parts, and the magnitude of the current to each of these separated electrodes is fed back to a separate power supply, the electrode 14 can be divided into three parts. A more uniform film thickness can be obtained.

Effects of the Invention As explained above, the present invention separates a cylindrical electrode into a plurality of parts in the axial direction, connects a power source to each of these separated electrodes individually, and supplies constant constant power from these power sources to the separated electrode. Since the amount of current is supplied, an amorphous Si layer can be uniformly formed on the membrane support even if the density of the reaction gas between the electrode and the membrane support changes. be.

[Brief explanation of the drawing]

Figure 1 is a side sectional view showing a conventional film forming apparatus;
The figure is a cross-sectional view thereof, FIG. 3 is a side cross-sectional view showing a film forming apparatus which is an embodiment of the present invention, and FIG. 4 is a cross-sectional view thereof. 12... Membrane support (drum substrate), 14a, 1
4b, 14c...separation electrode, 12a...amorphous Si layer, _P1 , _P2 , _P3 ...power supply.

Claims (1)

[Claims] 1. A method for forming an amorphous Si layer on the surface of a cylindrical membrane support by supplying a current to a cylindrical electrode and discharging it, wherein the cylindrical electrode is extended in its axial direction. A method for forming a film, characterized in that the separated electrodes are separated into a plurality of electrodes, each of the separated electrodes is individually connected to a power source, and a constant amount of current is constantly supplied to each of the separated electrodes from these power sources to form a film. 2. The film forming method according to claim 1, wherein the separation electrodes are arranged to face the upper, middle, and lower parts of the membrane support, respectively. 3 Monitor the current supplied to each separation electrode,
Claim 1 or 2, characterized in that when a current different from a predetermined current value flows, this is fed back to the power source and controlled so that a constant amount of current flows to each separation electrode. film formation method. 4 A cylindrical electrode comprising a plurality of separated electrodes provided facing a cylindrical membrane support and separated in the axial direction, and forming an amorphous Si layer on the surface of the membrane support by discharging. A structure characterized by comprising: a plurality of power supplies connected to each of the separation electrodes of the electrode for supplying current; and a control means for controlling the current flowing from these power supplies to the separation electrode to a constant value. Membrane device.