JPH049872B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a deposited film forming apparatus using a vapor phase method, particularly,
This article relates to devices for forming deposited films using discharge energy such as plasma CVD methods, glow discharge methods, and arc discharge methods, and in particular to devices suitable for forming film bodies constituting photoconductive members such as electrophotographic photoreceptors. . [Prior art] One of the methods for manufacturing deposited films is CVD (Chemical Vapor Deposition), which uses heat, light, or discharge energy.
There are three methods: deposition method, glow discharge method, and arc discharge method, and in particular, CVD method using low-temperature plasma has been attracting attention in recent years. In this method, the pressure inside the reaction tank is reduced to a high vacuum, the raw material gas is supplied into the reaction tank, and then the raw material gas is decomposed by glow discharge to form a film on the substrate placed in the reaction tank. in,
For example, it is applied to the production of amorphous silicon films. The amorphous silicon film created by this method using silane gas (SiH ₄ ) as a raw material gas has relatively few localized levels in the forbidden band of amorphous silicon, and due to doping with substitutional impurities, valence electrons are reduced. It can be controlled and has excellent properties as an electrophotographic photoreceptor, and is therefore highly anticipated. By the way, for example, an electrophotographic photoreceptor generally has a photoconductive layer provided on a cylindrical (drum-shaped) base for forming a deposited film, but plasma CVD
When producing a cylindrical electrophotographic photoreceptor by this method, an apparatus having a configuration as shown in FIG. 3 has conventionally been used. That is, this device includes a vacuum chamber container 51, an upper lid or gate 52 of the container, a DC or high frequency cathode electrode 54 connected to a power source 53, an exhaust system 55 for reducing the pressure inside the container, and a gas for forming a deposited film. It is equipped with a gas introduction system 56 for introducing gas, a heater 57 for heating the substrate, and the like. A normally conductive cylindrical substrate 58 housed in a vacuum chamber 51 is attached to an electrically grounded rotating shaft 59 and rotated by a drive motor 60 during deposition film formation. Further, 61 is a shield plate for confining plasma. By the way, in this type of vacuum chamber container, since the rotation mechanism is located at the axial center of the container, the exhaust hole for evacuating the inside of the container or reducing the pressure is provided offset from the axial center. That is, conventionally, for example, a single exhaust hole 62 with a large diameter is provided as shown in FIG. 4, or a plurality of exhaust holes 63 with a small diameter are provided as shown in FIG.
63, 63, 63, but the following problems arose. () At the exhaust port shown in FIG. 4, the flow of gas inside the vacuum chamber becomes non-uniform, making it impossible to obtain a uniform plasma reaction within the chamber, resulting in poor uniformity of the deposited film formed on the substrate. () In order to compensate for the drawbacks of (), the device shown in Fig. 5 has a plurality of exhaust ports located symmetrically with respect to the center. In order to obtain a uniform reaction within the container, the greater the number of exhaust ports, the better, but on the other hand, the problem is that the shape of the reactor becomes complicated, and the number of joints for the exhaust pipe increases, which is disadvantageous in terms of leak prevention and poor equipment reliability. , If the total effective area of the exhaust ports is the same in order to make the effective displacement the same, the number of exhaust ports (pipes) n
The relationship between and the effective inner diameter d _o of each exhaust port (pipe) is d _o = d ₁ /√n, and the larger the number, the smaller the effective diameter per one pipe. This thing is
Powder, which is a by-product generated during plasma reaction, tends to cause powder clogging during the reaction process.
As a result, it is difficult to maintain a constant internal pressure inside the vacuum chamber, making it difficult to form a stable film. Therefore, the present inventors have conducted extensive studies to solve the above-mentioned problems associated with conventional deposited film forming methods. As a result, when a deposited film is formed using a device with a specific structure and configuration, unexpectedly uniform film formation is obtained, and the stability of the internal pressure (discharge) during the reaction process is improved, and the deposited film formed is improved. The present invention was completed by discovering that the desired characteristics can be easily obtained. [Objective and Summary of the Invention] The object of the present invention is to maintain the uniformity of the film formation and improve the stability of the discharge when forming a deposited film using a discharge phenomenon, while maintaining uniform and excellent characteristics. An object of the present invention is to provide a deposited film forming apparatus capable of forming a deposited film. The above object is to provide a cylindrical reaction vessel for forming a deposited film on the substrate by generating an electric discharge between the cylindrical substrate housed with their axes aligned, and a cylindrical reaction vessel provided within the reaction vessel. In a deposited film forming apparatus having a gas supply pipe for supplying raw material gas and an exhaust pipe communicating with the reaction tank, the reaction tank accommodates a cylindrical substrate in a stationary state. The gas supply pipe and the exhaust hole each have a plurality of them, and are symmetrical with respect to the axis of the reaction tank, and the exhaust pipe has a plurality of exhaust holes at an end of the reaction tank. This is accomplished by a deposited film forming apparatus that is in communication with the reaction tank via a deposited film forming apparatus, and has a single exhaust pipe at a connection portion with the reaction tank. [Embodiments] Hereinafter, embodiments of the present invention will be described with reference to the attached drawings. FIG. 1 is a schematic diagram showing a configuration example of a deposited film forming apparatus of the present invention equipped with a cylindrical conductive substrate. The apparatus shown in FIG. 1 includes a cylindrical reaction vessel 1 which is made of a conductive structural material such as stainless steel, aluminum, nickel, or an alloy made of these materials as a substrate, and which can function as a cathode electrode.
This container 1 is a cylindrical conductive substrate holder that is fixed via a suspension member 4 to a container bottom plate 3 that is fixed via an annular insulator 2, and is arranged to be approximately aligned with the axis of the reaction tank container 1. 5, and a cylindrical conductive substrate 6 is placed on this pedestal 5 with its axis substantially aligned with the reaction tank container. FIG. 2 is a cross-sectional view of FIG. 1 taken by cutting the cylindrical conductive substrate holder 5 along a straight line. As shown in FIG. 2, the suspension member 4 (dotted line portion and broken line portion) includes a disk-shaped support 7 for supporting the base holder, and this support 7 and the container bottom plate 3.
It is comprised of four leg members 8 for bridging and forming exhaust holes 9, and the gaps between the leg members 8 serve as the exhaust holes 9. A conductive substrate holder 5 (shaded area) is provided on the disk-shaped support 7 so as to be approximately aligned with the axis thereof, and a resistance heating element 19 (shaded area) is provided inside the conductive substrate holder 5. part) are arranged. In the example shown here, the support 7 and the leg member 8 form the same plane as the suspension member 4 . Although the number of leg members 8 can be determined arbitrarily, it is preferable that the leg members 8 are arranged so as to radiate from each other at a constant angle with respect to the axis of the container 1 in order to make the arrangement of the exhaust holes uniform. Below the suspension member 4, an exhaust pipe 10 whose upper end is widened into a flap shape and fixed to the back surface of the bottom plate 3 is arranged, and is connected to an appropriate evacuation means such as a rotary pump or a mechanical booster pump (not shown). 11 is a valve. Reference numeral 12 denotes an upper lid or gate detachably or slidably attached to the container 1 via an annular insulator 13. Note that the substrate holder does not have to be cylindrical, and may have any shape as long as it can stably place the substrate, but by making it the same cylindrical shape as the substrate,
The device structure can be simplified in terms of arranging heaters and the like. Furthermore, by making the diameter of the cylindrical pedestal substantially the same as or slightly larger than that of the base body, it is possible to contribute to stabilization of glow discharge. Reference numerals 14 and 14 denote gas introduction pipes for forming a deposited film, and in order to maintain uniformity of film formation, a plurality of gas introduction holes 15, 15, 15 are uniformly distributed over a length that is almost the same as the length of the substrate. ..., and for the same reason, it is preferable that a plurality of them are arranged substantially concentrically at substantially uniform angles around the axis of the substrate in the gap between the reaction tank container and the substrate. Furthermore, for the same reason, in relation to the exhaust hole 9, it is preferable that the exhaust hole and the gas introduction pipe 14 are in a point-symmetrical relationship with respect to the axis of the reaction tank container. In the example shown in FIGS. 1 and 2, four gas introduction pipes, including those not shown, are arranged at approximately 90 degrees to each other. Each of the gas introduction pipes 14, 14, . Introductory tube 17
is further connected to a cylinder or the like which is a gas supply source for forming the deposited film. Further, numeral 18 in FIG. 1 is a high frequency matching box electrically connected to the reaction tank container 1, and this matching box (not shown) oscillates a high frequency in a practical high frequency band of 1 km to 1 GHz, for example. It can be connected to a high frequency oscillator to supply high frequency power to the container 1. Furthermore, 19 is a resistance heating element, which allows temperature control to maintain a desired substrate temperature. When carrying out the method of the present invention using an apparatus having such a configuration, first open the top cover or gate 2, put the cylindrical conductive substrate 6 into the container 1, and place the container 1 and the container 1 on the substrate holder 5. Place it so that its axis is almost aligned.
Next, the upper lid or gate 12 is closed and the exhaust pipe 10 is evacuated to reduce the pressure inside the reaction tank to a degree of vacuum of about 10 ^-2 to ^{10 -6} Torr.
A deposited film forming gas is introduced from . Furthermore, the conditions for glow discharge are 150°C as the substrate temperature.
~350°C is preferred, and the cathode (reactor vessel) is
Cooled as desired. Hereinafter, specific examples for demonstrating the effects of the present invention will be described. Example 1, Comparative Example 1, Comparative Example 2 A photoconductive member for an electrophotographic photoreceptor was prepared using the apparatus shown in FIGS. 1 and 2 and the apparatus shown in FIGS. 4 and 5 as a comparative example. Created. As for the equipment conditions, the effective displacement is the same as when a certain amount of inert gas is introduced into the container using a vacuum pump with the same exhaust capacity.The overall length of the exhaust pipe is the same, and the exhaust hole diameter and exhaust pipe diameter are set so that the internal pressure inside the container is the same. did. The conditions for producing the photoconductive member were as follows. [Fabrication conditions] Lamination order of deposited film Raw material gas used Film thickness (μm) Charge injection blocking layer SiH ₄ , B ₂ H ₆ 0.6 Photoconductive layer SiH ₄ 20 Surface protective layer SiH ₄ , C ₂ H ₄ 0.1 Substrate (aluminum cylinder ) 5 temperature: 250
Controlled at ℃±5℃ Deposition chamber internal pressure during deposited film formation: 0.3 Torr Discharge frequency: 13.56MHz Deposited film formation rate: 20 Å/sec Discharge power: 0.18 W/cm ² Gas flow rate: 200 m/s Gas flow rate: Charge injection prevention Layer SiH ₄ 200SCCM
B ₂ H ₆ 200 ppm relative to SiH ₄ Photoconductive layer SiH ₄ 200 SCCM Surface protective layer SiH ₄ 10 SCCM CH ₄ 200 SCCM Thus, the deposited film forming apparatus of the present invention (Figs. 1 and 2, Example 1, Fig. 4) Glow discharge conditions (discharge uniformity, circumferential potential unevenness) when using the apparatus shown in Figure 3 (Comparative Example 1) and the apparatus shown in Figure 5 (Comparative Example 2) , potential unevenness in the direction of the bus line (axis)), stability of the internal pressure of the reaction tank (internal pressure variation ΔP), dust clogging of the exhaust hole, image blurring formed by the formed photoconductive member, and yield of the photoconductive member were measured or evaluated.The results are shown in Table 1.

〔Effect of the invention〕

The effects of the present invention will be summarized as follows based on the embodiments described above. 1. By arranging the exhaust hole approximately concentrically with the cylindrical substrate, uniform discharge can be obtained without rotating the substrate, and a uniform film can be obtained. 2 By reducing the number of exhaust holes to one, the ratio of the exhaust pipe surface area to the effective exhaust diameter can be reduced.
It can prevent powder clogging during the reaction process. 3. By preventing powder clogging, the internal pressure is stabilized during the reaction process, the charging ability is stabilized, and image blurring does not occur. Stable characteristics are reproduced. 4. The device configuration is simplified and leaks can be prevented. 5. The device configuration is simplified and the device cost is advantageous.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram for explaining a configuration example of a deposited film forming apparatus of the present invention equipped with a base. FIG. 2 is a schematic diagram for explaining the arrangement of exhaust holes at the end of the reaction tank of the apparatus shown in FIG. 1. FIG. 3 is a schematic diagram for explaining the configuration of a conventional deposited film forming apparatus. Figures 4 and 5 are
FIG. 4 is a schematic diagram for explaining an example of the arrangement of exhaust holes at the lower end of the conventional deposited film forming apparatus as shown in FIG. 3; DESCRIPTION OF SYMBOLS 1... Reaction tank container, 3... Container bottom plate, 4... Suspension member, 5... Substrate pedestal, 6... Substrate, 9...
Exhaust hole, 10...Exhaust pipe, 12...Top lid or gate, 14...Gas introduction pipe, 18...High frequency matching box.

Claims (1)

[Claims] 1. A cylindrical reaction vessel for forming a deposited film on the substrate by generating an electric discharge between a cylindrical substrate housed with their axes aligned, and a raw material gas provided in the reaction vessel. In a deposited film forming apparatus having a gas supply pipe for supplying a gas, and an exhaust pipe communicating with the reaction tank, the reaction tank accommodates a cylindrical substrate in a stationary state, A plurality of the gas supply pipes and a plurality of the exhaust holes are provided, and these are in a point-symmetrical relationship with respect to the axis of the reaction tank, and the exhaust pipe is provided at an end of the reaction tank through the exhaust hole. A deposited film forming apparatus, characterized in that the apparatus is in communication with the reaction tank, and the exhaust pipe is a single exhaust pipe at a connection part with the reaction tank.