Abstract:
The object of the present invention is to provide a deposited film forming apparatus and deposited film forming method that can efficiently, cheaply, and stably supply high-quality amorphous silicon devices. This object is achieved by providing a vacuum vessel capable of providing a substrate therein, evacuating the inside of the vacuum vessel by an evacuation means, introducing a gas from gas supply means into the vacuum vessel, and applying high-frequency power from a high-frequency power source, thereby generating a plasma, wherein the evacuation means comprises at least two evacuation means as first evacuation means and second evacuation means, wherein the vacuum vessel is moved while maintaining a vacuum between the two evacuation means, and wherein the vacuum vessel is capable of being connected to each of the evacuation means, high-frequency power source, and gas supply means through a detachable connection mechanism.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a vacuum processing apparatus and vacuum processing methods typified by deposited film forming apparatus and deposited film forming methods using plasma enhanced CVD capable of forming on a substrate a deposited film. This invention relates more particularly to the formation of a functional deposited film, especially a non-monocrystalline semiconductor typified by amorphous semiconductors, an insulating coating such as silicon nitride, silicon carbide, or amorphous carbon, used in semiconductor devices, light-receiving members for electrophotography, line sensors for image input, image pickup devices, photovoltaic devices, and so on. 
     2. Related Background Art 
     Deposited films of semiconductors or the like made of amorphous materials such as amorphous silicon, for example, amorphous silicon compensated by hydrogen and/or halogen, have been proposed as element members for use in semiconductor devices, light-receiving members for electrophotography, line sensors for image input, image pickup devices, photovoltaic devices, other various electronics elements, and so on. Some of them are in practical use. 
     A variety of device forming apparatuses using amorphous silicon as described above have been proposed heretofore. For example, Japanese Patent Application Laid-open No. 58-83855 discloses a forming apparatus (of the coaxial type) for an amorphous silicon photosensitive member in which the cathode electrode and a cylindrical substrate are arranged on a coaxial basis. Further, Japanese Patent Application Laid-open No. 62-219524 discloses an example of a forming apparatus (of the concentric circle type) for an amorphous silicon photosensitive member with improved productivity, in which cylindrical substrates are arranged on one circle. 
     With recent improvements in overall performance of devices using amorphous silicon materials as described above, however, demands have increased for further improvement in the quality of the materials themselves, including various characteristics of amorphous silicon materials. 
     For example, in the field of electrophotography, there has been a strong push to save space and to lower prices in order to improve office environments. 
     On the other hand, demands have increased for further increase of copy image definition and for further increase of image formation speed. Under such circumstances demands for a decrease in the diameter of amorphous silicon photosensitive members and for commonality thereof have increased. At the same time, the tendency to specialize with respect to the diameters of photosensitive members also exists in order to make configurations optimum for characteristics of the electrophotographic process. 
     Under such circumstances, the conventional deposited film forming apparatus did not always meet the demands in some cases. 
     For example, in the case where an amorphous silicon photosensitive member for electrophotography was formed by the deposited film forming apparatus of the coaxial type as described above, changing the diameter of the photosensitive member also changed the diameter of a support member. It also resulted in changing the distance to the cathode and the like. This changed forming conditions of the deposited film, and in order to deal with the change, the apparatus needed to be modified, including the diameter of the cathode, change of evacuation position, and so on. Such modification normally required a period of several days. 
     In the case of the deposited film forming apparatus of the concentric circle type as described above, changing the diameter of the photosensitive member required changing the placement of substrates in order to form the discharge space. The modification usually required several days, too. 
     The dead time for the apparatus during modification caused degradation of operation rates of the starting material gas supply means and the evacuation system, thereby requiring big investments and other incidental facilities. 
     If photosensitive members of different diameters are intended to be produced by changing other deposition conditions without modifying the deposited film forming apparatus in order to avoid dead time, the apparatus configuration would deviate from the optimum shape. This would inevitably result in the occurrence of dispersion in the characteristics of the deposited film and the like or often requiring still more improvements for fully meeting recent, high desired performance demands. 
     The above problems occur not only in the case of formation of a deposited film, but also in the case of plasma processing of a surface to be processed. In such a case, it is considered important to optimize the configuration of the overall apparatus and its characteristics, due to variations in etch amount, modification amount, etc., though these variations are not as prominent as in the formation of deposited film. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is, therefore, to provide a vacuum processing apparatus and vacuum processing method, typified by the deposited film forming apparatus and deposited film forming method, capable of efficiently, cheaply, and stably supplying non-monocrystalline semiconductor devices including high-quality amorphous silicon devices meeting the above demands and solving the above problems. 
     Another object of the present invention is to provide a vacuum processing apparatus and vacuum processing method capable of supplying non-monocrystalline semiconductor devices while suppressing dispersion of characteristics, by facilitating supply of desired gas such as starting material gas into a movable vacuum vessel, thus preventing the occurrence of leakage or the like, and stabilizing the supply of gas. 
     An object of the present invention is to provide a vacuum processing apparatus comprising a vacuum vessel capable of providing a substrate therein, the vacuum processing apparatus being arranged to evacuate the inside of the vacuum vessel by evacuation means, introduce a gas from gas supply means into the vacuum vessel, and apply high-frequency power from a high-frequency power source to electrodes, thereby generating a plasma, wherein the evacuation means comprises at least two evacuation means as first evacuation means and second evacuation means, wherein the vacuum vessel is moved between the two evacuation means while maintaining vacuum, and wherein the vacuum processing apparatus comprises a connection mechanism capable of detachably connecting the vacuum vessel to each of the evacuation means, high-frequency power source, and gas supply means. 
     Another object of the present invention is to provide the vacuum processing apparatus wherein the first evacuation means can be used as evacuation means for evacuating the vacuum vessel from atmospheric pressure to a vacuum and the second evacuation means can be used as evacuation means for evacuating the inside of the vacuum vessel during generation of the plasma. 
     A further object of the present invention is to provide the vacuum processing apparatus wherein in a connection part between the vacuum vessel and gas supply means, the connection mechanism has a double structure of a starting material gas supply pipe through which a starting material gas flows and an external pipe for separating a connection portion of the pipe for supply of starting material gas from the atmosphere and permitting evacuation to a vacuum. If necessary, this external pipe is constructed as a pipe for detachably connecting the vacuum vessel to the evacuation means. 
     Still another object of the present invention is to provide the vacuum processing apparatus wherein the connection portion of the gas supply pipe comprises valves capable of sealing the connection portion before and after the connection portion and a pressure gauge for measuring a pressure inside the gas supply pipe between the valves. 
     A further object of the present invention is to provide a vacuum processing method for evacuating the inside of a vacuum vessel provided with a substrate therein by evacuation means, introducing a gas into the vacuum vessel and applying high-frequency power thereto, thereby generating a plasma inside the vacuum vessel, wherein the evacuation means comprises at least two evacuation means as first evacuation means and second evacuation means, the vacuum processing method comprising the steps of: connecting the vacuum vessel to the first evacuation means to evacuate the vacuum vessel from atmospheric pressure to a vacuum, disengaging and moving the vacuum vessel from the first evacuation means while maintaining vacuum, connecting the vacuum vessel with each of gas supply means, the second evacuation means for evacuating the inside of the vacuum vessel, and a high-frequency power source, supplying energy from the power source to generate the plasma, and disconnecting the vacuum vessel from the second evacuation means, the gas supply means, and the high-frequency power source. 
     Another object of the present invention is to provide the vacuum processing method further comprising a step of, in connecting the vacuum vessel with the gas supply means, replacing the atmosphere inside of a gas supply pipe through which a gas flows with an inert gas, and thereafter measuring a seal pressure of a connection portion. 
     Another object of the present invention is to provide the vacuum processing method capable of, during generation of the plasma with the vacuum vessel being connected to the second evacuation means, gas supply means, and high-frequency power source, connecting another vacuum vessel to the first evacuation means and setting a substrate in or evacuating the other vacuum vessel. 
     In the vacuum processing apparatus of the present invention, achieving the above objects, the evacuation means is fixed, and the vacuum vessel is freely movable. Therefore, for example, when vacuum vessels preliminarily prepared to be suitable for the production of desired amorphous silicon devices are used, no modification is necessitated for the vacuum processing apparatus (deposited film forming apparatus in the case of formation of deposited film) even for the production of many kinds and small numbers of lots. In this way, the dead time of the producing apparatus can be minimized. Since optimum configurations can be selected for respective vacuum vessels suitable for production methods of respective individual amorphous silicon devices, high-quality devices can be provided on a stable basis. 
     Further, since the vacuum vessel is movable, when a plurality of vacuum vessels are used, one vacuum vessel can be subjected to maintenance at a position apart from the evacuation means, while formation of a deposited film can be carried out in another vacuum vessel. 
     Accordingly, the dead time of a deposited film forming apparatus can also be minimized from this point, and high-quality devices can be supplied at low prices. 
     The present invention is effective not only in the formation of deposited film, but also in applications to plasma processing such as etching or modification of a processed body by use of plasma (for example, compensation for dangling bonds by hydrogen plasma). However, when the present invention is applied to the formation of a deposited film, its most prominent effect is seen in the fabrication of devices of higher performance and higher quality. Thus, the application to the formation of a deposited film is a preferred application. Particularly, a preferred application is the fabrication of devices having a non-monocrystalline material such as amorphous silicon, especially fabrication of optical devices typified by the photosensitive members for electrophotography. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic, structural drawing which shows a preferred example of the configuration of the vacuum processing apparatus according to the present invention; 
     FIG. 2 is a schematic, cross-sectional, structural drawing which shows a preferred example of the vacuum vessel of the vacuum processing apparatus; and 
     FIGS. 3,  4 ,  5  and  6  are schematic, structural drawings, each of which explains a preferred example of the connection mechanism used in the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will be described in detail by reference to the drawings. 
     FIG. 1 is a schematic, structural drawing which shows an example of the deposited film forming apparatus of the present invention. 
     This apparatus is mainly composed of vacuum vessel  100 , starting material gas supply means  200 , evacuation unit  102  as first evacuation means for evacuating the vacuum vessel  100  to a vacuum, evacuation unit  103  as second evacuation means for evacuating starting material gases from the vacuum vessel  100  during formation of deposited film, and high-frequency power source  105 . The evacuation unit  102  is connected to connection mechanism  107  through evacuation pipe  109 , and the second evacuation unit  103  is connected to connection mechanism  108  through vacuum pipe  110 . 
     In FIG. 1, the starting material gas supply means  200  is connected to the vacuum vessel  100  through starting material gas supply pipe  113  and starting material gas connection mechanism  300 . The starting material gas connection mechanism  300  is connected to evacuation pipe  114  branching off from the evacuation pipe  110 , thereby enabling the evacuation of the inside of the starting material gas supply path. The high-frequency power source  105  is connected via high-frequency transmission circuit  111  and connection mechanism  106  to the vacuum vessel  100 . The vacuum vessel  100  is arranged to be separated at the connection mechanisms  106 ,  108 ,  300  and to be moved freely, and it is capable of being also connected to the evacuation unit  102  through the connection mechanism  107 . 
     The frequency of energy supplied from the high-frequency power source  105  may be any one of those used in ordinary plasma enhanced CVD, and it is selected preferably from so-called radio frequencies (the RF band) and the VHF band. A specific example of the frequency band applicable is the range of 10 MHz to 450 MHz. For supplying the energy into the vacuum apparatus, a part of the vacuum vessel may be used as an electrode or a separate electrode from the main body of the vacuum vessel may be provided. 
     FIG. 2 is a schematic, cross-sectional view of an example of the vacuum vessel in the deposited film forming apparatus of the present invention for forming the amorphous silicon photosensitive member. 
     In the example of FIG. 2, the vacuum vessel  100  is constructed so that vacuum furnace  138  is placed on movable carriage  147 . 
     Casters  148  are attached to the movable carriage  147 , whereby the whole of vacuum vessel  100  is movable. 
     Matching box  145  is connected via high-frequency transmission circuit  146  to the vacuum furnace  138 , thereby comprising high-frequency introducing means. 
     The high-frequency introducing means is further connected to connection mechanism  106  for connection to the high-frequency power source. In this case, the wall surface of vacuum furnace  138  also serves as the cathode electrode. This wall surface is configured in close fit with pedestal  136  and door  141  through insulators  137 ,  140  and is insulated from the earth. 
     Starting material gas supply pipes  139  and cylindrical, conductive substrate  142  are installed inside the vacuum furnace  138 . 
     Heater  143  can be placed, if necessary, inside the cylindrical, conductive substrate. 
     The starting material gas supply pipes  139  penetrate the pedestal  136  to be connected to starting material gas introducing pipe  133  and further to valve  134 , thereby comprising starting material gas introducing means. 
     The starting material gas introducing means is connected to connection mechanism  300  for connection with the starting material gas supply means. Exhaust ports  149  are formed in the pedestal  136  and are connected to evacuation pipe  132 . 
     Vacuum gauge  131  and valve  135  are connected to the evacuation pipe  132  to be further connected with connection mechanism  108  for connection to the evacuation unit. 
     The vacuum vessel  100  can be moved while maintaining vacuum by closing the door  141  and valves  134  and  135 . 
     FIG. 3 is a schematic, structural drawing of an example of the connection mechanism for connecting the starting material gas introducing means with the starting material gas supply means in the deposited film forming apparatus of the present invention. 
     In the example of FIG. 3, the starting material gas supply pipe  113  and starting material gas introduction pipe  133  are connected by couplers  302 ,  301  capable of being engaged or disengaged. Evacuation pipe  114  connected through valve  304  enables the evacuation of the inside of starting material gas supply pipe  113 . 
     The evacuation pipe  114  may be configured to be connected to the evacuation pipe  110  so as to be evacuated by the second evacuation unit as shown in FIG. 1 or may also be configured to be evacuated by a separate evacuation unit. 
     Next described is an example of procedures for forming a deposited film by use of the apparatus shown in FIGS. 1 to  3 . 
     First, the vacuum vessel  100  in which the high-frequency introducing means and starting material gas introducing means were preliminarily set is connected through the connection mechanism  107  to the evacuation pipe  109  and evacuation unit  102 . 
     Then the cylindrical, conductive substrate having been degreased is set in the vacuum vessel  100 . Here, the door  141  provided in the top part of vacuum furnace  138  and the valve  134  are closed, and the valve  135  and an evacuation valve (not illustrated) provided in the connection mechanism  108  are opened to evacuate the inside of vacuum furnace  138  to a vacuum. Observing the indication of vacuum gauge  131 , the valve  135  and the evacuation valve (not illustrated) provided in the connection mechanism  108  are closed at a desired pressure, and then the connection mechanism  108  is disconnected to detach the vacuum vessel  100  from the evacuation unit  102  while maintaining vacuum inside the vacuum vessel  100 . 
     Then the vacuum vessel  100  is moved to the predetermined position, where it is connected with the starting material gas supply means  200 , evacuation unit  103 , and high-frequency power source  105  through the connection mechanisms  300 ,  108 , and  106 , respectively. 
     The following is an example of procedures for introduction of starting material gas by use of the connection mechanism shown in FIG.  3 . 
     First, after connection of each connection mechanism is confirmed, the evacuation valve (not illustrated) provided in the connection mechanism  108  is opened to evacuate the inside of connection mechanism  108 . 
     In tandem with this, the valve  304  provided in the connection mechanism  300  is opened to evacuate the inside of starting material gas supply pipe  113 . After sufficient evacuation, the valve  304  is closed, then the inert gas such as Ar or He is introduced from the starting material gas supply means  200  into the starting material gas supply pipe  113  to fill the inside of pipe  113  up to before the valve  134 , and then the valve  304  is again opened to evacuate the inside. 
     This operation is repeated several times to sufficiently purge the inside of starting material gas supply pipe  113 . After that, the valve  304  is closed, and, while keeping the inside of starting material gas supply pipe  113  under pressure with the inert gas, for example, a gas leak detection liquid is applied to the coupler portion to check whether a leak is present. If no leak is observed, the valve  304  is opened to again evacuate the inside of starting material gas supply pipe  113 , and then starting material gas, for example, SiH 4 , CH 4 , or B 2 H 6 , is introduced thereinto. 
     The above completes the procedures for introducing the starting material gas to the inside of starting material gas supply pipe  113 . Then the valve  135  is opened to evacuate the inside of vacuum vessel  100 . 
     Checking the indication of vacuum gauge  131 , it is confirmed whether the pressure inside the vacuum vessel is lowered to below desired pressure, and after confirmation, the valve  134  is opened to introduce the starting material gas. 
     At this time, the starting material gas, for example SiH 4 , CH 4 , or B 2 H 6 , is introduced while suppressing pressure change by a needle valve (not illustrated) provided separate from the valve  134 . The starting material gas is supplied from cylinder  241  to  244  through regulator  231  to  234 , primary valve  221  to  224 , mass flow controller  211  to  214 , and secondary valve  201  to  204  and through the valve  251  to the starting material gas supply pipe. 
     After the starting material gas is supplied at desired flow rates into the vacuum vessel  100  and the inside of vacuum vessel  100  is adjusted to desired pressure by a pressure adjusting valve (not illustrated), the high-frequency power is supplied from the high-frequency power source  105  to induce glow discharge therein, thereby forming a deposited film on the substrate  142 . 
     Prior to this, the heater  143  provided in the vacuum vessel may also be connected to the power source, if necessary, thereby heating the substrate to a desired temperature between 20° C. and 500° C. 
     In this case, the substrate can also be heated while introducing the inert gas such as Ar or He from the starting material gas supply means. 
     After the desired deposited film is formed, supply of the starting material gas and high-frequency power is stopped and then the inside of starting material gas supply pipe  113  is purged according to the same procedures as described previously. 
     When the sufficient purge operation is completed, the evacuation valve (not illustrated) provided in the connection mechanism  108  is closed, the connection mechanisms  106 ,  108 ,  300  are disengaged, and the vacuum vessel  100  is detached from the respective units to be moved. 
     The deposited film formed is cooled if necessary, and thereafter the vacuum vessel  100  is made to leak by a leak mechanism (not illustrated). Then the substrate  142  is taken out, thereby completing the sequence of procedures for forming the deposited film. 
     The deposited film forming apparatus of the present invention can increase productivity, because the vacuum vessel can be moved while maintaining vacuum. 
     For example, during formation of a deposited film with one vacuum vessel being connected to the starting material gas supply mechanism, high-frequency power source, and evacuation unit, installation of a conductive substrate and evacuation to vacuum can be carried out with another vacuum vessel being connected to the first evacuation means. 
     With the deposited film forming apparatus of the present invention, as described above, even if one vacuum vessel is, for example, being maintained or modified formation of deposited film can be carried out with another vacuum vessel; therefore, there should be no decrease in the operation rates of the starting material gas supply means, evacuation means, and high-frequency power source, thereby obviating big investments and other incidental facilities and enabling the supply of cheap amorphous silicon devices. 
     For forming amorphous silicon photosensitive members of different diameters or the like, vacuum vessels of configurations optimum for the respective diameters are preliminarily prepared. In this way the problems of the conventional apparatus are not raised, including the decrease of operation rates due to modification of apparatus, occurrence of dispersion of characteristics due to use of the vacuum vessel deviating from the optimum configuration, and so on. 
     In the deposited film forming apparatus according to the present invention, the connection mechanism  300  between the vacuum vessel and the starting material gas supply means can be constructed in double structure. 
     FIG. 4 is a schematic, structural drawing schematically showing an example of the connection mechanism constructed in the double pipe structure. 
     In FIG. 4 the couplers  301 ,  302  are covered by external pipe  307  so as to be separated from the atmosphere. 
     The external pipe has such structure that it can be disengaged at the dotted-line portion of FIG. 4 into the vacuum vessel side and the starting material gas supply means side. Together with the starting material gas supply pipe, it is connected by a clamp (not illustrated) and a vacuum seal (not illustrated), and it can be evacuated to a vacuum while the evacuation pipe  114  is connected thereto through valve  306 . 
     The procedures for introduction of starting material gas by use of the introducing mechanism of FIG. 4 may include a procedure for evacuating the inside of external pipe  307  to a vacuum, in addition to the procedures of the above-stated introducing mechanism of FIG.  3 . 
     Specifically, in connecting the vacuum vessel with the starting material gas supply means, the couplers  301 ,  302  are first connected. 
     Then the valve  304  is opened to evacuate the inside of starting material gas supply pipe  113  to a vacuum. After completion of sufficient evacuation, the valve  304  is closed, and the inert gas such as Ar or He is introduced up to before the valve  134  from the starting material gas supply unit  200  into the starting material gas supply pipe  113 . Then the valve  304  is again opened to evacuate the inside. 
     This operation is repeated several times to perform the purge operation, and during this period the valve  306  is closed. 
     After execution of sufficient purge, the valve  304  is closed, and, for example, the gas leak detection liquid is applied to the coupler portion with the inside of starting material gas supply pipe  113  being maintained under pressure with the inert gas, thereby checking a leak. 
     After no leak is confirmed, the valve  304  is opened to again evacuate the starting material gas introducing pipe  113 . Then the valve  304  is closed, and the starting material gas is introduced into the starting material gas introducing pipe  113 . 
     In tandem with this, the external pipe  307  is attached to the couplers  301 ,  302 . After completion of evacuation of starting material gas introducing pipe  113  and at the time of close of valve  304 , the valve  306  is opened to evacuate the inside of external pipe  307 . 
     The above concludes the introduction of starting material gas, and then the formation of deposited film is carried out. Desirably, the valve  306  is opened during the formation of deposited film to continue evacuation of the inside of external pipe  307 . For disengaging the connection mechanism after formation of deposited film, the valve  306  is closed and thereafter the valve  304  is opened to purge the inside of starting material gas supply pipe  113  and to replace the inside with the inert gas. Then the inside of the external pipe  307  is made to leak by the leak mechanism (not illustrated), and the connection mechanism  300  is disengaged. 
     When the connection mechanism as shown in FIG. 4 is used, the starting material gas can be prevented from directly being discharged into the atmosphere even if the starting material gas leaks from the couplers  301 ,  302 . 
     There are cases where the starting material gas supply pipe is kept under pressure below atmospheric pressure, depending upon the conditions for the formation of a deposited film. In such cases, the atmosphere is also prevented from mixing into the starting material gas supply pipe, which prevents pollution due to generation of oxide inside the pipe and suppresses degradation of characteristics of a deposited film. As a consequence, occurrence of dispersion is suppressed in characteristics of a deposited film. It is also conceivable that a pressure gauge is provided in the connection part of the starting material gas supply pipe in the present invention. 
     FIG. 5 is a schematic, structural drawing schematically showing an example of the connection mechanism between the vacuum vessel and the starting material gas supply pipe, provided with a pressure gauge  309 . 
     In the apparatus of FIG. 5, valve  305  is provided in the starting material gas supply pipe and the pressure gauge  309  is connected thereto through valve  308 , thereby constructing the configuration capable of measuring the seal pressure of the connection portion of the starting material gas supply pipe. 
     The procedures for introduction of starting material gas by use of the connection mechanism of FIG. 5 may include a procedure for measuring the seal pressure of the connection portion of the starting material gas supply pipe, in addition to the procedures for formation of deposited film in the case of the above-stated introducing mechanism of FIG.  4 . 
     Specifically, after connection of each connection mechanism is confirmed, the valves  304 ,  305 ,  306 ,  308  are opened to evacuate the inside of the starting material gas introducing pipe  113  and external pipe  307 . After sufficient evacuation, the valves  304  and  306  are closed, and the inert gas such as Ar or He is introduced up to before the valve  134  from the starting material gas supply unit  200  into the starting material gas supply pipe  113 . Then the valve  304  is again opened to evacuate the inside. 
     This operation is repeated several times to perform the purge operation, and during this period the valve  306  is kept closed to seal the pipe in vacuum. Then the inside of the pipe is purged sufficiently, the inert gas is introduced up to before the valve  134  into the starting material gas supply pipe  113 , the valve  305  is closed, and thereafter the seal pressure is measured inside the pipe sealed by the valves  134 ,  304 , and  305 , with the vacuum gauge  309 . 
     During the measurement of pressure, the valve  306  is preferably opened to evacuate the inside of the external pipe  307 . 
     After no reduction of pressure is confirmed within a predetermined time, the valve  306  is closed, and the valves  304 ,  305 ,  308  are opened to evacuate the inside of starting material gas introducing pipe  113 . After that, the starting material gas, for example, SiH 4 , CH 4 , or B 2 H 6 , is introduced. If there is decrease in pressure during measurement of seal pressure, a leak exists from the portion of couplers  301 ,  302 . Then the connection mechanism  300  is disengaged and it is checked and repaired. After that, the connection mechanism  300  is again connected, and the above operations are repeated. 
     The above completes the introduction of starting material gas, and then the formation of deposited film is carried out. During the formation of deposited film, the valve  306  is desirably opened to continue evacuation of the inside of external pipe  307 . 
     For disconnecting the connection mechanism after formation of deposited film, the valve  306  is closed, and thereafter the valves  304 ,  305 ,  308  are opened to purge the inside of starting material gas supply pipe  113  and to replace the inside with the inert gas. Then the inside of external pipe  307  is made to leak by the leak mechanism (not illustrated), and the connection mechanism  300  is disengaged. 
     Since the connection mechanism of FIG. 5 can detect occurrence of leak in the portion of couplers  301 ,  302  by the measurement of seal pressure, it does not have to use the gas leak detection liquid or the like for checking the leak, which was used in the example of FIG.  1  and FIG. 2, and the all steps can be carried out by automatic control. It is also free of a risk of polluting the inside of the pipe with the gas leak detection liquid remaining therein upon disengagement of couplers. 
     In measuring the seal pressure inside the pipe closed by the valves  134 ,  304 ,  305 , the pressure introduced into the pipe may be any pressure higher than the pressure of the pipe during actual formation of deposited film. For example, in the deposited film forming conditions in Example 1, the pressure inside the pipe is about 50 kPa, and any pressure higher than this pressure may be applied. Since the inside of external pipe  307  is evacuated to a vacuum (e.g., to the pressure of about 16 Pa in the conditions of Example 1), the leak can be checked even under the condition of the low pressure as described above. 
     However, the leak check is desirably carried out under the condition of 100 kPa or more for achieving the pressure measurement within a shorter time and with high accuracy. 
     In the pressure measurement, criteria for determination of what degree of pressure decrease should be regarded as presence of leak differ depending upon the forming conditions of deposited film and aimed characteristics. In general, pressure decrease of within 5% of the initial pressure would pose no problem in practical use. 
     The certainty for detecting the leak increases with longer time for measuring the seal pressure. In practice, however, times of not less than 30 seconds raised no problem in terms of the characteristics of deposited film. It is noted that the above pressure values and times differ depending upon the actual deposited film forming conditions and performance of apparatus and are not absolute conditions for carrying out the present invention. 
     It is also conceivable that a pipe for introduction of inert gas is provided between the valve  305  and the coupler  301 , separate from the starting material gas supply pipe in the apparatus of FIG.  5 . 
     In this case, the purge operation does not have to be conducted for the portion of starting material gas introducing pipe  113  ranging from the starting material gas introducing mechanism  200  to the valve  305 , so that engagement or disengagement of the connection mechanism can be conducted efficiently. 
     In the present invention, the external pipe  307  of the connection mechanism  300  may be arranged to serve also as an evacuation pipe of the vacuum vessel  100 . 
     FIG. 6 is a drawing schematically showing an example of the connection mechanism in which the external pipe also serves as an evacuation pipe. 
     The example of FIG. 6 is constructed in a combined configuration of the connection mechanism  300  for connecting the vacuum vessel  100  to the starting material gas supply mechanism  200 , with the connection mechanism  108  for connecting the vacuum vessel  100  to the second evacuation unit  103 . 
     In FIG. 6, the vacuum vessel and second evacuation mechanism are coupled through flanges  316  and  317 , they are fixed by a clamp (not illustrated), and O ring  314  is set in the flange  316 . 
     Valve  135  and evacuation valve  115  are placed with the coupling portion of the flanges in between, thus comprising a configuration which permits the connection mechanism to be disengaged while keeping the evacuation unit and vacuum vessel in vacuum. 
     Pipe  318  for evacuation is in communication with a portion between the evacuation valve  115  and flange  316  through valve  319 , so that the portion between the valve  135  and evacuation valve  115  can be evacuated independently. This pipe can be omitted if it is not necessitated in design of the apparatus. In that case, the inside of the connection mechanism can be evacuated by opening the evacuation valve  115 . 
     The starting material gas supply pipe is sealed by O ring  315 , through which the vacuum vessel side and the evacuation unit side (the starting material gas supply means side) are connected. 
     Since the O ring  315  is separated from the atmosphere by the O ring  314 , the starting material gas is prevented from being discharged to the atmosphere even in the event of occurrence of leak from the O ring  315 . 
     The following is an example of procedures for introduction of starting material gas with use of the connection mechanism of FIG.  6 . 
     First, after connection of each connection mechanism is confirmed, the valve  319  is opened to evacuate the inside of connection mechanism  108 . 
     At the same time, the valves  311 ,  313  are opened to evacuate the starting material gas supply pipe  113 . After sufficient evacuation, the valve  313  is closed, and the inert gas such as Ar or He is introduced up to before the valve  134  from the starting material gas supply unit  200  into the starting material gas supply pipe  113 . Then the valve  313  is again opened to evacuate the inside. 
     This operation is repeated several times to perform the purge operation, and during this period the valve  319  is opened to evacuate the inside of the connection mechanism  108 . 
     After sufficient purge, the inert gas is introduced up to before the valve  134  into the starting material gas supply pipe  113 , and thereafter the valve  311  is closed. Then the seal pressure in the pipe sealed by the valves  134 ,  311 , and  313  is measured by the pressure gauge  309 . 
     During the measurement of pressure, the valve  319  is preferably opened to evacuate the inside of the connection mechanism  108 . 
     If no decrease of pressure is recognized within the predetermined time, the valves  311 ,  313  are opened to evacuate the inside of the starting material gas introducing pipe  113 , and thereafter the starting material gas, for example, SiH 4 , CH 4 , or B 2 H 6 , is introduced. 
     The above completes the introduction of starting material gas, and then the formation of deposited film is carried out. During the formation of deposited film, the valve  319  is closed, and the evacuation valve  115  is opened to effect evacuation. 
     For disconnecting the connection mechanism after the formation of deposited film, the valve  134  is closed, and thereafter the valves  311 ,  313  are opened to purge the inside of starting material gas supply pipe  113  and to replace the inside with the inert gas. After that, the inside of the connection mechanism  108  is made to leak by the leak mechanism (not illustrated), and the connection mechanism  108  ( 300 ) is disengaged. 
     When the connection mechanism as shown in FIG. 6 is used as described above, it can simplify the apparatus configuration and the procedures for introduction of starting material gas and for disengagement of the connection mechanism. 
     The specific examples of the deposited film forming apparatus according to the present invention were described above, and the present invention will be further described with examples thereof. It is, however, noted that the present invention is by no means intended to be limited to these examples. 
     Experiment Example 1 
     An amorphous silicon deposited film was formed according to the aforementioned procedures under the conditions of Table 1 by use of the deposited film forming apparatus of the present invention shown in FIGS. 1 to  3 . In this example, an aluminum cylinder of the cylindrical shape having the length 357 mm and the diameter 108 mm was used as a conductive substrate. The vacuum vessel used in this example was preliminarily designed so as to match this substrate. The frequency of the high-frequency power supplied was 105 MHz. 
     
       
         
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
             
             
               
                   
                 Starting material gas flow 
                 300 
               
               
                   
                 rate 
               
               
                   
                 SiH 4  (sccm) 
               
               
                   
                 Substrate temperature (° C.) 
                 120 
               
               
                   
                 Internal pressure (Pa) 
                 50 
               
               
                   
                 High-frequency power (W) 
                 500 
               
               
                   
                   
               
             
          
         
       
     
     With the deposited film thus produced, thicknesses of deposited film were measured at seventeen points in total at intervals of 2 cm along the direction of the generating line from the center of the substrate. A ratio of the maximum thickness value to the minimum thickness value among them was evaluated as nonuniformity of thickness. 
     Experiment Example 2 
     An amorphous silicon deposited film was formed according to the aforementioned procedures under the conditions of Table 2 by use of the deposited film forming apparatus of the present invention shown in FIGS. 1 to  3 . In this example, an aluminum cylinder of the cylindrical shape having the length 357 mm and the diameter 60 mm was used as a conductive substrate. The vacuum vessel used in this experiment example was preliminarily designed so as to match this substrate, and it was different in placement of the starting material gas introducing pipes and exhaust ports and in the diameter of cathode from the vacuum vessel used in Experiment Example 1. 
     
       
         
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
             
             
               
                   
                 Staring material gas flow 
                 230 
               
               
                   
                 rate 
               
               
                   
                 SiH 4  (sccm) 
               
               
                   
                 Substrate temperature (° C.) 
                 120 
               
               
                   
                 Internal pressure (Pa) 
                 50 
               
               
                   
                 High-frequency power (W) 
                 500 
               
               
                   
                   
               
             
          
         
       
     
     With the deposited film thus produced, thicknesses of deposited film were measured at seventeen points in total at intervals of 2 cm along the direction of the generating line from the center of the substrate in the same manner as in Experiment Example 1. A ratio of the maximum thickness value to the minimum thickness value among them was evaluated as nonuniformity of thickness. 
     Comparative Experiment Example 1 
     An amorphous silicon deposited film was formed under the conditions shown in Table 1 and according to the aforementioned procedures, using the vacuum vessel used in Experiment Example 1 and using the cylindrical, conductive substrate (the length 357 mm, the diameter 60 mm) used in Experiment Example 2. With the deposited film thus produced, thicknesses of deposited film were measured at seventeen points in total at intervals of the 2 cm along the direction of the generating line from the center of the substrate in the same manner as in Experiment Example 1. A ratio of the maximum thickness value to the minimum thickness value among them was evaluated as nonuniformity of thickness. 
     Comparative Experiment Example 2 
     An amorphous silicon deposited film was formed under the conditions shown in Table 1 and according to the aforementioned procedures, using the vacuum vessel used in Experiment Example 2 and using the cylindrical, conductive substrate (the length 357 mm, the diameter 108 mm) used in Experiment Example 1. With the deposited film thus produced, thicknesses of deposited film. were measured at seventeen points in total at intervals of 2 cm along the direction of the generating line from the center of the substrate in the same manner as in Experiment Example 1. A ratio of the maximum thickness value to the minimum thickness value among them was evaluated as nonuniformity of thickness. 
     The results of Experiment Examples 1, 2 and Comparative Experiment Examples 1, 2 described above are shown in Table 3. In Table 3, the nonuniformity of thickness is relatively evaluated, with the result of Experiment Example 1 being set to be 1. 
     
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                 TABLE 3 
               
               
                   
                   
               
               
                   
                   
                   
                 Comparative 
                 Comparative 
               
               
                   
                 Experiment 
                 Experiment 
                 Experiment 
                 Experiment 
               
               
                   
                 Example 1 
                 Example 2 
                 Example 1 
                 Example 2 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Nonuniformity 
                 1 
                 1.06 
                 1.18 
                 1.23 
               
               
                 of thickness 
               
               
                   
               
             
          
         
       
     
     As apparent from the results of Table 3, the nonuniformity of thickness becomes worse with change in the diameter of the conductive substrate and without modification of the vacuum vessel. With the vacuum vessels designed so as to match the diameters of the conductive substrate, good results of nonuniformity of thickness, equivalent to each other, were obtained for each of the diameters. 
     EXAMPLE 1 
     An amorphous silicon photosensitive member for electrophotography was made according to the aforementioned procedures and under the conditions of Table 4 by use of the deposited film forming apparatus of the present invention shown in FIGS. 1 to  3 . In the present example, an aluminum cylinder of the cylindrical shape having the length 357 mm and the diameter 30 mm was used as a conductive substrate. The vacuum vessel used in the present example was the one preliminarily designed so as to match this substrate. 
     
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 4 
               
               
                   
               
               
                   
                 Charge 
                   
                   
               
               
                   
                 injection 
               
               
                   
                 preventing 
                 Photoconductive 
                 Surface 
               
               
                 Layer structure 
                 layer 
                 layer 
                 layer 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Starting material gas 
                   
                   
                   
               
               
                 flow rate 
               
               
                 SiH 4  (sccm) 
                 250 
                 250 
                 20 
               
               
                 B 2 H 6  (ppm) 
                 1000 
                 0.2 
               
               
                 (vs SiH 4 ) 
                   
               
               
                 CH 4  (sccm) 
                   
                   
                 200 
               
               
                 Substrate temperature 
                 210 
                 210 
                 210 
               
               
                 (° C.) 
               
               
                 Internal pressure (Pa) 
                 30 
                 45 
                 25 
               
               
                 High-frequency power (W) 
                 600 
                 800 
                 500 
               
               
                 Thickness (μm) 
                 3 
                 20 
                 0.5 
               
               
                   
               
             
          
         
       
     
     The “thicknesses” in above Table 4 are approximate indices in designing the light-receiving member for electrophotography. 
     Twenty lots of photosensitive members for electrophotography were produced under the above conditions, and chargeability was measured for each of the photosensitive members for electrophotography. The chargeability was measured in the following manner: 
     Each photosensitive member for electrophotography produced was set in an electrophotographic apparatus modified for experiments from GP55 available from CANON Inc., the voltage of 6 kV was applied to a charger thereof to effect corona charging, and dark potentials were measured by a surface potential meter. 
     EXAMPLE 2 
     An amorphous silicon photosensitive member for electrophotography was made according to the aforementioned procedures and under the conditions of Table 4 by use of the deposited film forming apparatus of the present invention shown in FIGS. 1 and 2 and the connection mechanism shown in FIG.  4 . In the present example, the aluminum cylinder of the cylindrical shape having the length 357 mm and the diameter 30 mm was used as a conductive substrate. The vacuum vessel used in the present example was the one preliminarily designed so as to match this substrate. 
     Twenty lots of photosensitive members for electrophotography were produced under the above conditions, and chargeability was measured for each of the photosensitive members for electrophotography. 
     EXAMPLE 3 
     An amorphous silicon photosensitive member for electrophotography was made according to the aforementioned procedures and under the conditions of Table 4 by use of the deposited film forming apparatus of the present invention shown in FIGS. 1 and 2 and the connection mechanism shown in FIG.  5 . In the present example, the aluminum cylinder in the cylindrical shape having the length 357 mm and the diameter 30 mm was used as a conductive substrate. The vacuum vessel used in the present example was the one preliminarily designed so as to match this substrate. 
     Twenty lots of photosensitive members for electrophotography were produced under the above conditions, and chargeability was measured for each of the photosensitive members for electrophotography. 
     EXAMPLE 4 
     An amorphous silicon photosensitive member for electrophotography was made according to the aforementioned procedures and under the conditions of Table 4 by use of the deposited film forming apparatus of the present invention shown in FIGS. 1 and 2 and the connection mechanism shown in FIG.  6 . In the present example, the aluminum cylinder in the cylindrical shape having the length 357 mm and the diameter 30 mm was used as a conductive substrate. The vacuum vessel used in the present example was the one preliminarily designed so as to match this substrate. 
     Twenty lots of photosensitive members for electrophotography were produced under the above conditions, and chargeability was measured for each of the photosensitive members for electrophotography. 
     The chargeability is evaluated according to the following criteria: 
     A: There is little dispersion of chargeability, and thus the results are very good. 
     B: There is dispersion of chargeability, but the overall results are within the specifications of the electrophotographic apparatus. 
     C: There is dispersion of chargeability, and some of the results do not satisfy the specifications. 
     
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                 TABLE 5 
               
               
                   
                   
               
               
                   
                 Example 
                 Example 
                 Example 
                 Example 
               
               
                   
                 1 
                 2 
                 3 
                 4 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Chargeability 
                 B 
                 B 
                 A 
                 A 
               
               
                   
               
             
          
         
       
     
     From the results of Table 5, the dispersion of chargeability is slightly greater in Examples 1 and 2. It is presumed that the gas leak detection liquid used in the leak check intruded into the pipe upon disengagement of the couplers and affected the characteristics. However, the dispersion is small in both Examples 1 and 2 and the good results were achieved in either case by the deposited film forming apparatus of the present invention. 
     In the present invention, as described above, the vacuum vessel is freely movable, and thus the deposited film forming means does not have to be modified even in the production of many types and low volume, by preliminarily preparing the vacuum vessels optimum for production of desired amorphous silicon devices. The present invention can minimize the dead time of the production apparatus, without lowering the operation rates of the starting material gas supply means and evacuation system requiring big investments for facilities and the other incidental facilities. 
     Since optimum vacuum vessel configuration can be selected so as to match the production of individual amorphous silicon devices, high-quality devices can be provided on a stable basis. 
     Further, since the vacuum vessel can be moved while maintaining in vacuum, maintenance of a vacuum vessel can be carried out at a position separate from the evacuation means with use of a plurality of vacuum vessels, and during that period, formation of deposited film can be carried out with another vacuum vessel. From this point, the dead time of a deposited film forming apparatus can also be minimized, and high-quality devices can be supplied on a stable basis.