JPH0456450B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to, for example, a film forming method for manufacturing a large number of amorphous silicon photoreceptor drums continuously and in a much shorter time than conventional methods.

[Technical background of the invention and its problems]

FIG. 1 shows an example of a conventional film forming apparatus for an amorphous silicon photoreceptor (hereinafter referred to as a-Si photoreceptor) drum. Referring to the film forming apparatus shown in FIG. 1, a conventional film forming method for an a-Si photoreceptor drum will be explained step by step. First, the inside of the reaction vessel 1 is evacuated to about 10 ^-5 Torr using a diffusion pump and a rotary pump (not shown). At the same time, the temperature of the drum-shaped substrate 3 is raised to 150°C to 250°C by the heater 2. Next, the valve 4 is opened to introduce a gas containing Si into the reaction vessel 1, and at the same time, the exhaust system is switched from a diffusion pump and rotary pump system (not shown) to a mechanical booster pump 5 and rotary pump 5 system. Gas containing Si is supplied to the drum-shaped base 3 from the gas ejection pipe/counter electrode 7.
Mechanical booster pump 5
After passing through a rotary pump 6 and a combustion tower and a scrubber (not shown), it is discarded. The gas containing Si is introduced into the reaction vessel 1 at a constant flow rate through a mass flow controller (not shown). In addition, in the figure, 9A is a rotating base, and 9B is 9A.
A gear 9C is integral with the gear 9B, and a drive gear 9E is driven by the motor 9D.
is an exhaust pipe, and 9F is a filter.

Then, the pressure inside the reaction vessel 1 is 0.1 to 1 Torr.
After adjusting the capacity of the exhaust system so that The film formation of the a-Si photoreceptor is started on the surface of No. 3. However, when forming a film on an a-Si photoreceptor using such a film forming method, first the inside of the reaction vessel 1 is evacuated to 10 ^-5 Torr, and at the same time the temperature of the drum-shaped substrate 3 is raised to 150°C to 250°C. It takes at least 1 hour. Furthermore, since the current film formation rate of the a-Si photoreceptor is 6 μm/hour at the maximum, it takes about 2.5 hours to form the film to obtain a film thickness of 15 μm, which is necessary for the photoreceptor. Furthermore, after film formation, a drum-shaped substrate 3 is used to avoid sudden temperature changes when the a-Si photoreceptor drum is taken out into the atmosphere.
It is necessary to wait for about 1 to 2 hours to slowly cool the temperature from 150°C to 250°C to at least 100°C or lower. As a result, it took a total of about 6 hours to form a film on one a-Si photoreceptor, which caused problems in mass production.

In order to improve the above problems, the present inventors have already proposed a film forming method suitable for mass production of a-Si photoreceptor drums as shown in FIG. That is, a first vacuum chamber 13 and a second vacuum chamber 14 are provided via the reaction vessel 10 and gate valves 11 and 12.

First, the first vacuum chamber 13, the reaction vessel 10, and the second vacuum chamber 14 are evacuated to 10 ^-5 Torr using the rotary pump 15 and the mechanical booster pump 16. At this time, the first vacuum waiting room 1
The plurality of conductive drum-shaped substrates 17A arranged in the drum 3 are heated to a predetermined temperature between 150° C. and 250° C. by heaters 18. Next, the gate valve 11 is opened and the plurality of drum-shaped substrates 17A...
After moving the rotary bases 25A from the first vacuum chamber 13 into the reaction vessel 10 on rails (not shown), the gate valve 11 is closed. Next, the valve 20 is opened and a raw material gas containing Si such as SiH ₄ (silane) or Si ₂ H ₆ (disilane) or, if necessary, a gas containing Si and impurities such as O ₂ , NH ₃ , CH ₄ etc. A mixed gas is introduced into the reaction vessel 10. Needless to say, at this time, the gas introduced into the reaction vessel 10 is adjusted to a predetermined flow rate by a mass flow controller (not shown).

After adjusting the opening degree of the valve 21 so that the gas pressure in the reaction vessel 10 becomes a predetermined value between 0.01 and 10 Torr, DC or AC power is applied to the counter electrode 22 facing the plurality of drum-shaped substrates 17B. is applied to generate raw material gas plasma such as a Si-containing gas or a mixed gas of a Si-containing gas and an impurity gas, and start forming a film on the a-Si photoreceptor. On the other hand, the vacuum state inside the first vacuum waiting chamber 13 is released, the interior is divided at the O-ring 23, and a plurality of new drum-shaped substrates 17A are formed.
...is set. After that, the parts of the O-ring 23 are combined again, and the exhaust system (not shown) is used again.
A vacuum of 10 ^-5 Torr is drawn. At this time, it goes without saying that the new drum-shaped substrate 17A is heated again to a predetermined temperature between 150°C and 250°C. After forming a film on the a-Si photoreceptor for about 3 hours, in the reaction vessel 10, first, the application of power to the counter electrode 22 is stopped, and then the valve 20 is closed, and the Si-containing gas or the Si-containing gas and the impurity gas are removed. The introduction of the raw material gas such as the mixed gas is stopped, and the valve 21 is fully opened to bring the inside of the reaction vessel 10 into a vacuum state of 10 ^-5 Torr again. At this time, the first vacuum chamber 13, the reaction container 10, and the second vacuum chamber 14 are all under a vacuum of 10 ^-5 Torr. Open the gate valves 11 and 12 and remove the a-Si photoreceptor drum 17B inside the reaction container 10.
... into the second vacuum antechamber 14 or the drum-shaped substrate 17A in the first vacuum antechamber 13... is the reaction vessel 10
Each moves inside on a rail (not shown).

The gate valves 11 and 12 are closed, and the second a-Si photoreceptor film forming process begins in the reaction vessel 10. The vacuum state is released in the first reaction vessel 13, and a new drum-shaped substrate is formed. is set. After slowly cooling the a-Si photoreceptor drum for a predetermined period of time, the second vacuum chamber 14 is released from the vacuum state, is divided at the O-ring 24, and the a-Si photoreceptor drum is exposed to the atmosphere. taken out. In this manner, the method of forming an a-Si photoreceptor film previously proposed by the present inventors has made it possible to form films continuously on a plurality of drum-shaped substrates without wasting time. In addition, in FIG. 2, 25A is a bearing that rotatably supports the rotary base 25A, 25C is an exhaust pipe, 25D is a base, 2
5E is a shaft for driving the rotating base 25A, 25F is a gear mechanism that transmits the driving force of the motor 25G to the shaft 25E, 25H is an exhaust pipe,
25I is a valve provided in the exhaust pipe 25H, 25
J is an exhaust pipe, and 25K is a valve installed in the exhaust pipe. By the way, since the film forming time of the a-Si photoreceptor in the reaction vessel 10 remains unchanged at 3 hours,
For example, if the heating time in the first vacuum anteroom 13 is 1.5 hours and the slow cooling time in the second vacuum anteroom 14 is 1.5 hours, then if all the steps are performed simultaneously,
I wasted 1.5 hours.

[Purpose of the invention]

The present invention was developed based on the above circumstances, and it is possible to significantly increase the film formation speed compared to conventional film formation methods, and to prevent the generation of unnecessary powdery by-products, resulting in highly efficient film formation. The purpose of the present invention is to provide a film forming method that can be stably performed.

[Summary of the invention]

The present invention provides a reduced pressure system in which a space containing an electrode and a conductive substrate is surrounded by an electrically grounded cylindrical conductive mesh that allows the flow of raw material gas through the mesh and can act as a plasma barrier. In the reaction chamber under this condition, a necessary amount of raw material gas is introduced into the inside of the conductive mesh through the mesh by flowing the raw material gas through the spatial region within the conductive mesh and the region around the conductive mesh. Along with the gas introduction process and this gas introduction process,
a film forming step of generating plasma in a region between the electrode and the conductive substrate to form a film containing atoms contained in the raw material gas on the conductive substrate; The distance between the conductive mesh and the conductive mesh is smaller than the mean free path of electrons in the plasma during film formation.

[Embodiments of the invention]

Hereinafter, the present invention will be explained with reference to the drawings.
First, the principle of the present invention will be explained with reference to FIGS. 3 and 4. In the a-Si film deposition equipment for flat substrates with the structure shown in these figures, the deposition rate is 16 μm/
It turns out that time moves extremely quickly. That is,
A base 31 for setting the flat substrate 30 and a counter electrode 32 facing the substrate 30 are surrounded by a conductive mesh 34, and the plasma of gas containing Si generated between the base 31 and the counter electrode 32 is transferred to the mesh 34. This is the principle that by confining the plasma to the inside, the plasma positive column 35, which had been biased toward the counter electrode, expands to the substrate 30, thereby dramatically increasing the deposition rate of the a-Si film. In addition, in the figure, 36A is a high frequency power supply, 36B is a reaction vessel, 36C is an exhaust pipe, and 36D
is a valve provided in the exhaust pipe 36C, 36E is a heater, 36F is a source gas introduction pipe, 36G is a valve provided in the gas introduction pipe 36F, and d ₁ is a distance for dark space shielding.

The present invention is based on this principle, and the fifth
6 and 7 show an apparatus for mass production of a-Si photoreceptors suitable for the film forming method of the present invention. FIG. 5 is a sectional view of a mass production apparatus for a-Si photosensitive drums according to the present invention. The basic configuration is the same as the mass production device shown in FIG. 2, but in the device of the present invention, the reaction vessel 40
Inside, conductive meshes 42 and 43 are provided above and below a plurality of conductive drum-shaped substrates 41B. 6th
The figure is the A-A' cross section in Figure 5, and Figure 7 is the 5-5 cross section.
This is a cross section taken along line BB' in the figure. As can be seen from FIG. 6, the upper mesh 42 is provided on almost the entire surface. The lower mesh 43 has a plurality of drum-shaped substrates 41B transferred from the vacuum chamber 44 to the reaction vessel 40 or from the reaction vessel 4.
When moving from 0 to the vacuum waiting room 45, only the passage 47 for the rotating shaft 49 is open (see FIG. 7). When the drum-shaped substrates 41B are in the fixed position in the reaction vessel 40, the movable mesh 48 provided further below the lower mesh moves in the direction of the arrow as shown in FIG. The meshes 43 and 4 are all connected to the base body except for the rotating shaft 49.
It has a structure surrounded by 8.

Further careful considerations have been made in the present invention. That is, the conductive mesh 50 and the counter electrode 5
1 and _{the distance d 2 between} the conductive mesh 43 and the counter electrode 51 are smaller than the mean free path of electrons in the plasma during film formation of the a-Si photoreceptor. Normally, the conductive meshes 42 and 43 are grounded through the inner wall of the reaction vessel 40, so abnormal discharge occurs between the counter electrode 51 and the meshes.
The applied power will be consumed at that location.
However, in the present invention, since d ₁ and d ₂ serve as so-called dark space shields, such abnormal discharge does not occur.

In addition, in the figure, 41A is a conductive drum-shaped substrate, and 50
A is a rotary base, and 50B rotatably supports the rotary base 50A. Bearing, 50C is exhaust pipe, 50
D is the base, 50E is the motor 50 on the rotating base 50A.
The shaft that transmits the driving force of F, 50G is the exhaust pipe, 50H is the valve installed in the exhaust pipe 50G,
50I is an exhaust pipe, 50J is a valve provided on the exhaust pipe 50I, 50K is a raw material gas introduction pipe, and 50L is a valve provided on the raw material gas introduction pipe 50K.

Also, 50M and 50N are gate valves,
50P is the rotation fulcrum of the mesh 48, and 50Q
is the heater, 50R is the O-ring, 50S is the exhaust pipe 5
This is a valve installed at 0C.

(Example) After a vacuum of 10 ^-5 Torr was once drawn in the reaction vessel 2 in which a mesh was provided on the top and bottom of the drum-shaped substrate of the present invention, the temperature of the conductive drum-shaped substrate was set at 250°C, and SiH was used as the raw material gas. ₄ was introduced into the reaction vessel 2 set at a reaction pressure of 1.0 Torr at a flow rate of 1000 SCCM, and an a-Si film containing hydrogen was formed for 1 hour with 1 KW of high-frequency power applied.
A-Si with a uniform film thickness of approximately 18μm for book drums
A photoreceptor was obtained. When these five a-Si photoreceptor drums were corona charged with a corona discharger to which -6.0KV was applied, a uniform surface potential of -250V was obtained, and by light irradiation with 2Lux tungsten light, a uniform surface potential of -250V was obtained. It exhibited a high photosensitivity of 0.6 Lux Sec, and obtained characteristics equivalent to those of a-Si photoreceptor drums deposited at a conventional slow deposition rate.

Furthermore, when a-Si photoreceptor drums were continuously formed in units of five using the above-mentioned a-Si photoreceptor drum mass production apparatus of the present invention, 30 a-Si photoreceptor drums were deposited in 8 hours.
-Production of Si photoreceptor drum was completed.

In addition, in the above-mentioned embodiment, the method for forming a film on a photoreceptor was explained, but it can be applied to forming a film on an optical sensor, etc.
It can also be used to form a film containing Ge.

〔Effect of the invention〕

As explained above, according to the present invention, a cylindrical conductive mesh surrounds the space between the electrode and the conductive substrate disposed in the reaction chamber, and the plasma of the raw material gas is transferred to the conductive mesh. Since the film is confined within the film, the film formation speed can be significantly increased compared to conventional film formation methods.

In addition, out of the raw material gas introduced into the reaction chamber, only the required amount of raw material gas can be introduced inside the conductive mesh through the mesh. It is possible to prevent the generation of powdery by-products and perform highly efficient film formation.

Also, the distance between the electrode and the conductive mesh is
Because it is smaller than the mean free path of electrons in the plasma during film formation, this part acts as a dark space shield, preventing abnormal discharge and eliminating the consumption of applied power, ensuring reliable film formation. It has the same effect as when you can do it.

[Brief explanation of the drawing]

Figure 1 is a schematic configuration diagram of a conventional film forming apparatus;
The figure is a schematic configuration diagram showing a prior art example of a mass-production type film forming apparatus, and Figures 3 to 8 show the configuration of an apparatus that can implement the present invention. Figure 3 is a diagram for explaining the principle. A schematic front view showing the basic configuration of the device, FIG. 4 is a schematic plan view, FIG. 5 is a schematic configuration diagram, FIG. 6 is a sectional view taken along the line A-A' in FIG. 5, and FIG. is a sectional view along the line B-B' in Figure 5, and Figure 8a.
is a sectional view taken along line C-C' in Figure 5, and Figure 8b is a cross-sectional view taken along line C-C' in Figure 5.
It is an enlarged view of part A of figure a. 40... Reaction container, 41B... Conductive drum-shaped substrate, 42, 43... Conductive mesh, 49...
Rotating shaft, 50M, 50N...gate valve, 51
...Counter electrode.

Claims (1)

[Scope of Claims] 1. A space containing an electrode and a conductive substrate surrounded by an electrically grounded cylindrical conductive mesh that allows the flow of source gas through the mesh and can act as a plasma barrier. A necessary amount of the raw material gas is passed through the conductive mesh into the conductive mesh by flowing the raw material gas through the spatial region within the conductive mesh and the area around the conductive mesh in a reaction chamber under reduced pressure including the conductive mesh. a step of introducing a gas into the inside of the gas; and together with this gas introduction step, generating plasma in a region between the electrode and the conductive substrate, and forming a film containing atoms contained in the raw material gas on the conductive substrate. A film forming method comprising: a film forming step of forming a film; and a distance between the electrode and the conductive mesh is smaller than the mean free path of electrons in plasma during film forming. . 2. The film forming method according to claim 1, wherein the conductive substrate is formed into a drum shape.