Patent Publication Number: US-6338872-B1

Title: Film forming method

Description:
This application is a division of application Ser. No. 08/704,138, filed Aug. 28, 1996. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a film forming apparatus and method for forming functional deposited films for photovoltaic elements or various kinds of sensors. More particularly, the invention relates to an improved film forming apparatus and method in which the maintenance time for continuous film formation such as a roll-to-roll film formation is shortened to enhance the working efficiency of the apparatus. 
     2. Related Background Art 
     A variety of semiconductor devices or electronic devices including photovoltaic elements or various kinds of sensors are provided with one or more functional deposited films on a substrate. In a manufacturing process of such devices, it is desired to form the deposited films as having certain level of characteristics continuously and efficiently to mass produce the products of superior characteristics. 
     For example, in a photovoltaic element such as a solar cell of the structure in which a plurality of semiconductor layers (i-layer, n-layer, p-layer) are laminated, various examinations for the stable film forming process have been made to enhance its function. 
     In recent years, a power generation system with a solar battery using the sunlight has drawn attention as a clean power generation system which can cope with increased demands for electric power in the future, without causing environmental destruction, since it does not bring about problems of radioactive pollution or global warming, uses a less maldistributed energy source, and further can accomplish a relatively high efficiency of power generation without needing complex and large installations. Various activities of research and development have been made for practical use of such a battery. 
     To establish the power generation system using the solar battery as meeting the demands for electric power, it is fundamentally required that the solar battery has a high enough photoelectric conversion efficiency, stable characteristics, and is capable of mass production. 
     In this respect, a solar battery which can be fabricated, using a source gas such as silane, in a gaseous body, which is easily available, by depositing a semiconductor film of e.g. amorphous silicon (hereinafter abbreviated as “a-Si”) on a relatively inexpensive substrate made of glass or metal, has been noted, such a battery is suited for mass production, with the possibility of lower production costs, as compared with the solar battery fabricated using a single crystal silicon. Various proposals have been made for the constitution of basic layers and the manufacturing methods thereof. 
     Although a-Si deposited film is formed on a band-like substrate by chemical vapor deposition (CVD) which typically occurs from the gas phase under reduced pressures, or sputtering, a plasma CVD method making use of glow discharge plasma is widely utilized because the characteristics of the deposited film are superior, and can be mass produced. 
     Recently, a plasma process making use of microwave has been also noted. The microwave, which is short in frequency band, can have a higher energy density than when using RF, and thus is suited for generating and sustaining plasma efficiently. 
     For example, in U.S. Pat. Nos. 4,517,223 and 4,504,518, a method of depositing a thin film on a substrate of small area within microwave glow discharge plasma under low pressures has been disclosed. With this method, since the film formation can be made via a process under low pressures, high quality deposited films can be produced by preventing polymerization of active species which may cause degraded film characteristics. In forming an Si film, the film forming speed can be remarkably increased, while generation of polymers such as polysilane in plasma is suppressed. 
     However, in microwave plasma, though much higher film forming speed may be typically expected, microwave applicator means making use of a microwave generator, an isolator, a waveguide, and an arsela ceramics window is needed to introduce microwave into a film forming chamber, resulting in higher costs than the conventional RF methods. Accordingly, for example, in the formation of a-Si film in manufacturing the a-Si solar cell, the microwave is used for fabrication of a photovoltaic layer (i-type a-Si layer) having large film thickness for which high throughput is required, while the RF method is used for making other layers, i.e., n-type a-Si layer and p-type a-Si layer. A so-called hybrid method has thus been proposed. 
     On the other hand, from the viewpoint of a film formation process, and in consideration of mass production of final devices, a continuous plasma CVD system which adopts a roll-to-roll (Roll to Roll) type substrate which is wound like a roll has been disclosed in U.S. Pat. No. 4,400,409. 
     With this apparatus, a plurality of glow discharge regions are provided, a flexible substrate having a desired width and a sufficient length is laid along a path extending through the glow discharge regions, through which the substrate is passed successively. A semiconductor layer of the required conduction type is deposited in the glow discharge regions, while the substrate is conveyed continuously in a longitudinal direction, to allow for the continuous formation of elements having semiconductor junctions. 
     Note that in U.S. Pat. No. 4,400,409, a gas gate was used to prevent dopant gas for use in forming each semiconductor layer from diffusing and mixing into other glow discharge regions. Specifically, the glow discharge regions are separated from one another by a slit-like separation passage, and the separation passage is provided with means for forming the flow of scavenging gas such as Ar or H 2 . In this respect, it can be said that the roll-to-roll type is suitable for mass production of semiconductor devices in which various functional films are laminated. 
     In addition, a continuous plasma CVD system of roll-to-roll type for forming a large area a-Si deposited film was disclosed in U.S. Pat. No. 4,485,125. 
     For a plasma process using microwave, a deposited film forming method and apparatus of roll-to-roll type using a microwave plasma CVD system was disclosed, for example, in Japanese Laid-Open Patent Application No. 3-30419. 
     A typical plasma CVD system of roll-to-roll type will be described below with reference to the drawings. 
     FIG. 1 is a cross-sectional view showing the constitution of the plasma CVD system of roll-to-roll type, and FIG. 2 is a cross-sectional view showing the constitution of a vacuum vessel (chamber) and a film forming chamber which are contained in the apparatus. In FIG. 1,  500  to  504  are vacuum vessels (chambers),  505  to  507  are film forming chambers,  508  to  510  are discharge electrodes,  511  to  513  are glow discharge spaces,  514  to  516  are rf oscillators,  517  to  519  are substrate heaters,  520  to  522  are gas heaters,  523  to  525  are source gas inlet ports,  526  is a magnet roller,  527  to  530  are gas gates,  531  to  533  are exhaust pumps,  534  to  535  are pressure gauges,  537  to  540  are gate gas inlet ports,  541  is a delivery bobbin,  542  is a winding bobbin, and  543  to  545  are gas gate exhaust ports. 
     FIG. 2 is a cross-sectional view of the apparatus (one vacuum vessel) as seen from the side. The prismatic vacuum vessels  500  to  504  are arranged on a straight line as viewed from the upper face, or like a catenary as viewed from the lateral side. The substrate for forming the film thereon is a band-like substrate  100  having a desired width and a sufficient length. 
     Provided inside the vacuum vessels  501  to  503  are film forming chambers  505  to  507 , respectively, in which desired semiconductor layers are formed on the band-like substrate  100  within the glow discharge spaces  511  to  513  which are enclosed by the band-like substrate  100 , the discharge electrodes  508  to  510 , and the film forming chambers  505  to  507 . 
     In FIG. 1, a vacuum vessel  500  at the left end as shown contains the delivery bobbin  541  for the band-like substrate  100 , and a vacuum vessel  503  at the right end as shown contains the winding bobbin  542 . 
     The band-like substrate  100  extending lengthwise as a band is made of a material having electrical conductivity, flexibility and magnetism such as stainless steel, is delivered from the delivery bobbin  541  to pass through the vacuum vessels  501  to  503  and the film forming chambers  505  to  507 , in succession, and wound around the winding bobbin  542 . 
     On a conveyance passageway of the band-like substrate  100 , there are disposed a plurality of magnet rollers  526  at appropriate locations thereof, which are magnetized and rotatable, to support the band-like substrate by magnetic suction to retain a predetermined conveyance passageway. 
     In FIG. 1, the film forming chambers  505  to  507  are connected to exhaust pumps  531  to  533  having an exhaust speed regulating function, to keep the inside of film forming chambers at desired pressures by measuring the pressure by means of the pressure gauges  534  to  536 , and controlling the exhaust speed of the exhaust pumps  531  to  533  by means of a pressure control device (not shown). 
     A plurality of different kinds of source gases are mixed into desired constituents by means of a gas mixer (not shown), and this mixed gas is fed through source gas inlet ports  523  to  525  into the film forming chambers. Also, the vacuum vessels are connected via the gas gates  527  to  530 , respectively, which have both functions of preventing mutual diffusion of source gases of adjacent vacuum vessels by isolating them, and passing the band-like substrate  100  therethrough. 
     A gas isolating function can be fulfilled by connecting adjacent vacuum vessels via a slit-like separation passageway, and flowing a separation gas (gate gas) from the upper and lower faces of the gas gate to collide with the source gas to shorten the diffusion length of the source gas. 
     Examples of the gate gas include H 2 , He and Ar. The exhaust pipes connected to the film forming chambers  505  to  507  are provided with the gate gas exhaust ports  543  to  545 , respectively, whereby the source gases or decomposed gases which flow out of the glow discharge spaces  511  to  513  are exhausted from the gate gas exhaust ports  543  to  545 , together with the gate gas, to prevent the gate gas and the mixed gases from adjacent vacuum vessels from entering the glow discharge spaces. 
     The above-described constitution of the apparatus of a double chamber structure having vacuum vessels and film forming chambers, with a gas gate provided between adjacent vacuum vessels, is an important technique for the plasma roll-to-roll type CVD system. 
     Even if the band-like substrate  100  is moved into a next vacuum vessel, the source gas within the vacuum vessel is not transferred. Further, even if there is any pressure difference within each vacuum vessel, mutual diffusion or mixture of source gases between adjacent vacuum vessels can be suppressed to a minimum, so that the semiconductor layers of desired conduction type having excellent characteristics can be deposited in succession on the band-like substrate  100 . 
     Referring now to FIG. 2, the internal structure of vacuum vessels  501  to  503  containing the film forming chambers  505  to  507  of FIG. 1 will be described below. 
     In FIG. 2,  700  is a film forming chamber,  701  is a feeder board,  702  is a shield,  703  is an rf introducing flange,  704  is a gas introducing flange,  705  is a gas introducing tube,  706  is a film forming chamber stay,  100  is a band-like substrate,  101  is a vacuum vessel,  102  is a ceiling plate,  104  is a discharge electrode,  105  is a guard electrode,  110  to  112  are insulators,  113  is a substrate heater,  114  is a gas heater,  115  is a heater supporting stay, and  118  is a glow discharge space. 
     In FIG. 2, RF power from the rf oscillator (not shown) is supplied via the rf introducing flange  703 , and the feeder board  701 , to the discharge electrode  104 . Also, the source gas is supplied via the gas introducing flange  704  into the film forming chamber  700 . 
     In FIG. 2, a space enclosed by the film forming chamber  700 , the band-like substrate  100 , the ceiling plate  102  and the discharge electrode  104  is the glow discharge space  118 . 
     By decomposing the source gas introduced into the glow discharge space  118  with RF power applied to the discharge electrode  104 , the semiconductor deposited film of desired conduction type can be formed on the band-like substrate  100 . The ceiling plate  102  is attached to the film forming chamber  700 , to form an upper lid of the film forming chamber  700 , along with the band-like substrate  100 . 
     Also, on the back face side of the band-like substrate  100 , the heater  113  is provided to heat the band-like substrate  100  to a proper substrate temperature. The source gas is heated by the gas heater  114 , and fed into the glow discharge space  118 . Also, the gas heater  114  heats the film forming chamber  700 , the discharge electrode  104  and the guard electrode  105 . 
     Heating of these has the effect of preventing the powder of polysilane produced by decomposition of the source gas from depositing on the wall face of film forming chamber  700  as well as the surface of discharge electrode  104 . 
     In order to form the film to be deposited on the band-like substrate  100 , with good controllability and reproducibility, it is requisite to introduce the RF power and the film forming gas into the film forming chamber  700  without leakage. 
     For example, to keep the RF power from leaking from the shield  702 , it is desired that the shield  702  is rigidly attached to a bottom face of vacuum vessel  101  without clearance, and that the feeder board  701  is made of copper having a high electrical conductivity. 
     However, because copper has also a high thermal conductivity, the feeder board  701  will be heated by thermal conduction from the discharge electrode  104  heated by plasma of the glow discharge space  118  and the gas heater  114 . 
     It is necessary to provide such a design that the feeder board  701  having caused thermal expansion does not make contact with the shield  702  by deformation. 
     Further, it is necessary to provide such a design that the source gas is introduced into the film forming chamber  700 , and may not leak into the vacuum vessel  101  except for the film forming chamber  700 . From the above reasons, the use of a bellows-like flexible mechanism for the feeder board  701 , the shield  702 , and the gas introducing tube  705  may be considered. However, this mechanism may possibly cause breakage due to changes with the lapse of time. In an apparatus which will operate long term as a production machine, because it is important to have reproducibility and reliability, the feeder board  701 , the shield  702  and the gas introducing tube  705  are desirably in the form of a durable rod. 
     The operation of the plasma CVD system of roll-to-roll type will be schematically described in the following. In FIG. 1, if the plasma CVD system is activated, the land-like substrate  100  delivered from the delivery bobbin  541  is continuously conveyed in a longitudinal direction thereof at a constant rate, passed through the film forming chambers  505  to  507  to form desired semiconductor layers in succession on the band-like substrate  100  within the glow discharge spaces  511  to  513 , and then wound around the winding bobbin  542 . 
     Finally, a plurality of sorts of semiconductor layers are laid down on the band-like substrate  100  to continuously form desired semiconductor junction devices. As a result, the semiconductor junction devices of large area can be mass-produced. 
     The apparatus as shown in FIG. 1 is a plasma CVD system of roll-to-roll type to form a photovoltaic element having one pin structure, i.e., a single cell, if applied to the manufacture of photovoltaic element. However, this apparatus is able to form a so-called triple cell having a pin-pin-pin structure with enhanced photoelectric conversion efficiency, if more film forming chambers are connected. 
     Generally, the whole size of the apparatus may be different depending on the production throughput, but the apparatus having the capability of producing photoelectric elements of triple type which generate about 10 MW of optical power for one year has approximately 20 film forming chambers, with the overall length of apparatus being about 40 m in a longitudinal direction. 
     In view of an example of the film forming process for a photovoltaic element such as a solar cell, as above described, fabrication of devices having multiple functional films can be applied as a mass production method having a greater throughput by reasonably combining a continuous film forming system such as roll-to-roll production as above described with various film forming processes. However, in such a mass production system which is considered to be ideal, the following problems arose. 
     Active species, precursors for forming the deposited film, may deposit on some regions of the film forming chamber other than the substrate of interest in the form of powder or film. 
     Such film deposited on some regions other than the substrate may be exfoliated from the bottom, beyond a certain limit of thickness. Some exfoliated film pieces may stick to the substrate, yielding defective portions on the deposited film. To prevent such a situation, cleaning the film forming chamber every time a certain number of film formations is reached, or the total time of film formation is exceeded. However, it takes considerable time to clean away the powder or film. For example, if using a file or brush to take off the film, more time and labor was required, and the small portion not easily accessible was difficult to clean. Also, in the case of powder, there was a risk of causing a fire. 
     Accordingly, a cleaning method in which only an easily detachable portion within the film forming chamber is removed, and reused by etching or blasting for regeneration. 
     Even with this method, it took much time to perform mounting or dismounting of individual parts, assembling, and the etching process, resulting in reduced availability of the apparatus. 
     A further problem, when using the roll-to-roll type apparatus, is handling of the band-like substrate at the time of maintenance. 
     When the film formation for the band-like substrate one wind of bobbin is completed, one does not fully take out the band-like substrate from the apparatus. Since it is difficult to pass a new band-like substrate through the film forming chambers and the gas gates, due to narrowness of a gap of gas gates (normally from 1 mm to 10 mm), it is common practice that the leading end of a new band-like substrate is bonded to, by adhesion or welding means, and pulled by the trailing end of the previously film formed band-like substrate in order to pass throughout the apparatus. 
     That is, the band-like substrate always exists in the film forming chamber, thereby hampering the maintenance operation for the film forming chamber. Sometimes a desired component can not be taken out due to presence of the band-like substrate. 
     FIG. 3 is a typical view representing such a situation. In FIG. 3,  301  is a vacuum chamber,  302  is a gas gate,  303  is a band-like substrate,  304  is an upper lid, and  305  is a film forming chamber. 
     As will be clear from the figure, the parts constituting the film forming chamber, can not be easily taken out, because the band-like substrate  303  is an obstacle. Also, the band-like substrate  703  is difficult to clean on the bottom side. Namely, with a batch-type film forming apparatus, the maintenance operation can be performed after taking out the substrate, while with a roll-to-roll type, the maintenance was difficult, because the substrate remains in the form of a lengthwise continuous body. 
     Also, with the film forming apparatus and process making use of the above-described band-like substrate, problems such as discharge leakage, deformation of band-like substrate, difficulty in conveying the band-like substrate, rupture, or short-circuit of rf introducing portion, may occur as a result of repeated heating and cooling of the vacuum vessels and film forming chambers by operation and stop of the apparatus. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to resolve the aforementioned problems in carrying out the continuous film formation on a substrate, and to provide a film forming apparatus where unnecessary matter, such as powder or film material deposited on sites other than the substrate, can be removed in a short time, thus improving maintenance and limiting apparatus down-time. 
     It is another object of the invention to resolve the aforementioned problems in carrying out the continuous film formation on a substrate, and to provide a film forming apparatus which can raise the yield of forming functional deposited films in various electronic devices by avoiding discharge leakage, abnormal discharge (local discharge), deformation or rupture of band-like substrate, or the trouble in conveying the substrate. 
     To accomplish the above objects, as a first form of the present invention, there is provided a film forming apparatus for performing a continuous process on a substrate to form multiple films, comprising a plurality of vacuum chambers in communication to each other via a connection, at least one vacuum chamber internally having a treatment room for performing a predetermined treatment on the substrate, which can be attached on or detached from said vacuum chamber. 
     To accomplish the above another object, as a second form of the present invention, there is provided a film forming apparatus for performing a continuous process on a substrate to form multiple films, comprising a plurality of vacuum chambers in communication to each other via a connection, at least one vacuum chamber internally having a treatment room for performing a predetermined treatment on the substrate, and a mechanism for adjusting the position within said vacuum chamber of said treatment room in a horizontal plane. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a view showing one example of a plasma CVD system of roll-to-roll type. 
     FIG. 2 is a view showing one example of the internal structure of a vacuum vessel for use with the apparatus as shown in FIG.  1 . 
     FIG. 3 is a view showing one example of a typical film forming apparatus of roll-to-roll type. 
     FIGS. 4 to  6  are views showing the structure of a vacuum chamber and a film forming chamber in one embodiment of a first film forming apparatus of the present invention. 
     FIG. 7 is a view showing the structure of a vacuum chamber in another embodiment of the first film forming apparatus of the present invention. 
     FIG. 8 is a view showing one example of a film forming apparatus of roll-to-roll type to which the present invention is applied. 
     FIG. 9 is a view schematically showing another example of a film forming apparatus of roll-to-roll type to which the present invention is applied. 
     FIGS. 10A and 10B are views showing one example of a pinch valve for use with the film forming apparatus of the invention. 
     FIG. 11 is a view showing a further example of a film forming apparatus of roll-to-roll type to which the present invention is applied. 
     FIG. 12 is a view showing the junction structure of a band-like substrate. 
     FIG. 13 is a view schematically showing a further example of a film forming apparatus of roll-to-roll type to which the present invention is applied. 
     FIG. 14 is a view showing the positional relation between vacuum chambers, treatment rooms and a substrate in the film forming apparatus of roll-to-roll type. 
     FIG. 15 is a view of the apparatus as shown in FIG. 14, as viewed from above. 
     FIG. 16 is a chart showing the displacement amount of the vacuum chamber in the apparatus for continuously forming the film on the band-like substrate. 
     FIG. 17 is a view showing the structure of a vacuum chamber and a film forming chamber in one embodiment of a second film forming apparatus of the present invention. 
     FIG. 18 is a view showing the structure of a joint of a feeder board within the vacuum chamber in one embodiment of the second film forming apparatus of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A first form of the present invention is an apparatus for performing the continuous film formation particularly on a substrate, having enhanced maintenance capability and less down-time, in which a film forming chamber can be pulled out of a vacuum chamber and detached therefrom. That is, a film forming apparatus for performing the continuous film formation on a substrate, comprising a plurality of vacuum chambers connected to each other via e.g. a gas gate, while having internally a treatment room such as a film forming chamber, a film forming space being formed by said substrate in contact with the opening side of the film forming chamber, wherein the film is continuously formed on the substrate while the substrate is being moved in a longitudinal direction of said plurality of vacuum chambers connected to each other, characterized in that said treatment room can be pulled out of said vacuum chamber, and detached from said vacuum chamber. 
     In the present invention, said treatment room, forming one face of vacuum chamber, can be pulled out of said vacuum chamber by removing a flange detachable from said vacuum chamber from said vacuum chamber. 
     In doing so, the flange supports detachably the treatment room by means of a support mechanism provided on the flange and extending in a direction into the vacuum chamber, wherein the treatment room is pulled out of the vacuum chamber by guiding the support mechanism via a guide mechanism. 
     Also, in cases where the treatment room is the film forming chamber, it is connected to a gas supply portion for supplying a film forming gas to the film forming chamber via a joint having an O-ring, wherein this gas supply portion is provided within the vacuum chamber and outside the film forming chamber in the state where the film forming chamber is placed within the vacuum chamber. 
     Further, with the present invention, the film forming chamber can be pulled out of the vacuum chamber by one-touch, in which a waveguide for introducing electric power provided on the side of the film forming chamber is connected via a connecting clamp to an applicator for applying electric power to the waveguide which is provided on the side of the flange for the vacuum chamber. 
     By using such apparatus of the present invention, after the end of the film forming process once to several times, the treatment room pulled out of the vacuum chamber can be replaced with a new treatment room which has been cleaned for the film formation. 
     The present invention is also effective not only for the cases of introducing microwaves into the film forming chamber as the treatment room, but also for introducing RF power for film formation. 
     A first embodiment of the first invention will be described in detail in the following. 
     The present invention can greatly enhance the maintenance capability and decrease down-time of the apparatus simply by replacing the film forming chamber, without taking extra time for cleaning, because the treatment room such as the film forming chamber can be pulled out of the vacuum chamber and removed therefrom, after the end of the film forming process once to several times, as above described. 
     In the following, the contents of the present invention will be more specifically described, based on the drawings. 
     FIGS. 4 to  6  are typical views showing an example of a film forming chamber and a vacuum chamber as a treatment room in a film forming (CVD) process using microwaves, constituting a film forming apparatus of the present invention. FIG. 4 is a cross-sectional view of one chamber taken along a direction perpendicular to the longitudinal direction of the film forming apparatus, showing the state where the film forming chamber is pulled out of the vacuum chamber, together with the flange of vacuum chamber, at the time of maintenance. 
     In FIG. 4,  401  is a vacuum chamber for placing the inside at reduced pressure, one face thereof being made up by a detachable flange  402 . In this figure, the flange has been separated and pulled out therefrom. 
       403  is a bracket secured to the flange and extending toward the inside of the vacuum chamber, for detachably placing a film forming chamber  404  thereon, and supporting a plate  405  internally having a gas introducing mechanism (not shown). Also, the plate  405  is also supported by a bracket  406 . The bracket  406  internally has a roller to be movable on a rail  407  in the directions of the arrow  416 . On the other hand, a flange  102  is connected to a conveyance guiding mechanism  408  outside the chamber, thereby allowing the film forming chamber to be smoothly pulled out, e.g., manually, from the inside of the vacuum chamber. 
     On the faces opposite the vacuum chamber, microwave applicator means ( 409   a ,  409   b ) for introducing microwaves into the vacuum chamber are inserted, respectively, and on the atmosphere side (outside) are connected to microwave waveguides, not shown, to supply microwave power from microwave generators, not shown. The vacuum chamber  401  and the film forming chamber  404  are connected via the microwave guiding paths (waveguides)  410   a ,  410   b  for introducing microwaves from applicators  409   a ,  409   b  into the film forming chamber. The wave guiding paths  410   a ,  410   b  and the applicators  409   a ,  409   b  are connected and secured together by clamps  111   a ,  111   b , respectively. 
     The upper side of the vacuum chamber  101  is an upper lid  112 , which can be opened and closed around a hinge  113  as a fulcrum in the direction of the arrow  422 . 
     On an inner side (inside the chamber) of the upper lid  112 , an infrared lamp heater  414  for heating the substrate is placed to heat the substrate  415  passing continuously through the vacuum chamber  401 . Also, the film forming chamber  404 , together with the waveguides  410   a ,  410   b , is designed to be easily detachable therefrom, with a portion indicated by the slant line being as a piece. 
     The side walls of the film forming chamber  404  at both ends in a longitudinal direction of the apparatus serve as the exhaust passage of film forming gases introduced into the film forming chamber  404 , and are formed of a porous plate (punching metal)  416  for enclosing microwaves within the film forming chamber. 
     The waveguides  410   a ,  410   b  are preferably made in the form of a so-called PF (plasma-free) window. For example, the PF window has a number of metal fins having a thickness of about 1 mm stacked at an interval of several millimeters, the microwaves can proceed through their voids without loss by matching with the microwaves in the oscillating direction thereof, while plasma will attenuate through the voids. Thereby, the abnormal heating of the applicator due to plasma can be prevented. 
     Note that the waveguide  410   a  of FIG. 4 schematically shows the behavior of a fin in the PF window. 
     Referring now to FIG. 5, the state where the film forming chamber as shown in FIG. 4 is inserted within the vacuum chamber will be described below. In FIG. 5,  201  is a vacuum chamber for evacuating the inside of the air, and  231  is an upper lid for making up the vacuum chamber, which has been closed to reduce the internal pressure in this figure. 
     One face of the vacuum chamber is formed by a detachable flange  241 , which is tightly secured to the vacuum chamber  201  via an O-ring (not shown) to reduce the internal pressure in this figure. 
     On the bottom face of the vacuum chamber, a valve  202  and a vacuum pump such as a diffusion pump are connected to make it possible to reduce the pressure within the vacuum chamber. As previously described in FIG. 4, the members  236 ,  237  making up the film forming chamber are a series of guide mechanisms for pulling out the film forming chamber, having a plate  205  for laying thereon the members  236 ,  237  on a guide mechanism  204 . Also, the plate  205  is connected with a film forming gas introducing pipe. At the other end of the gas introducing pipe  206  there is a joint  208  having an O-ring  207 , which is inserted into a connection sleeve  209  secured to the vacuum chamber side. Also, film forming gases are introduced from a gas supply unit, not shown, through the gas introducing flange  210  into the connection sleeve. 
     The connection between joint  208  and sleeve  209  is sealed by the O-ring  207 , so that the gas introduced from the gas supply device not shown into the gas introducing flange  210  can pass to the plate  205  without leakage. 
     The plate  205  has a cavity inside, such that the gas introduced through the pipe  206  into the cavity within the plate is discharged through a hole provided at the other end of the plate, through a gas discharge hole penetrating through a bottom plate of the film forming chamber into the film forming chamber. 
     On the other hand, the upper lid  231  is provided with an infrared lamp heater  233  via a bracket  232 . When an electric power controlled by a signal from a temperature sensor  235  provided in contact with the substrate  234  for forming the deposited film thereon is applied to the lamp heater, the substrate  234  is heated up to a desired temperature. A member  230  constituting the film forming chamber is secured to the bottom plate  237  which serves as a bottom member for the chamber wall. The bottom plate  237  is placed on the plate  205 , both plates being secured together by screw or clamp, as required. The microwave waveguide  242  is fixed to the applicator  244  by a clamp  243 . A film forming space is formed by the film forming chamber composed of members  236 ,  237  and the substrate  234 . 
     Referring now to FIG. 6, a maintenance process for the film forming apparatus as above described will be described below. FIG. 6 is an upper view showing the state where the film forming chamber has been pulled out, at maintenance time. 
     In FIG. 6,  311  is a vacuum chamber,  312  is a plate pulled out forwards by sliding it via a guide mechanism  313 , on which the film forming chamber  314  is laid. On both sides of the film forming chamber  314  are provided punching plates, the film forming gas discharged through the gas discharge hole  316  passing through a punching metal  315  out the film forming chamber  317 . Thereafter, the gas is exhausted out of the system through a vacuum pipe not shown connected to the gas exhaust port  317 . 
     Note that  318  is an exhaust port for evacuation of the air to be used in beginning to pull vacuum from a state near the atmospheric pressure. 
     In the following, using the film forming apparatus of roll-to-roll type according to the present invention as above described, a film forming process and a maintenance process which are carried out in practice will be described below with reference to FIG.  4 . 
     Referring to FIG. 4, the maintenance process will be first described below. After the end of a first film forming process, the system is sufficiently purged, and after cooling, the exhaust valve is closed to introduce the inert gas such as N 2  or Ar into the system to place the interior of the vacuum chamber at an atmospheric pressure. After the inside of the chamber has been made atmospheric pressure, jigs such as bolts for securing the flange  402  to the vacuum chamber  401  are removed. 
     Subsequently, the upper lid  412  is opened, and the clamp  411  for securing the microwave waveguide  410  to the applicator  409  is removed. 
     Thereafter, the flange  412  is pulled out, using the rail  417  and the guide mechanism  418 , along with the parts of the film forming chamber  414 , to take out the film forming chamber  404  from the vacuum chamber  401 . 
     Then, the securing jigs such as screws for securing the film forming chamber  414  to the plate  415  are removed. 
     In this state, the film forming chamber  414  can be easily removed in the form of cassette, together with the microwave waveguide. 
     In place of the removed film forming chamber, a new film forming chamber which has been cleaned is placed on the plate  405 . 
     The removed film forming chamber is to be cleaned and regenerated by the time when the newly installed film forming chamber is removed again. 
     Preferably, several film forming chambers are prepared for use in rotation. 
     If the new film forming chamber has been installed, the film forming chamber is moved into the vacuum chamber. Thereafter, the flange  402  is fixed to the vacuum chamber  401  by means of screw and a vacuum seal is provided. 
     Subsequently, the waveguide  410  and the applicator  409  are connected by the clamp  411 , the lid  412  is closed, and a vacuum seal is provided. 
     Referring now to FIGS. 5 and 6, a preprocessing and a film forming process will be described below. 
     After the film forming chamber is inserted into the vacuum chamber, with vacuum seals provided at all sites (FIG.  5 ), the valve connected to an exhaust port  318  for roughing as shown in FIG. 6 is opened to reduce the pressure within the system. 
     If the vacuum chamber has been placed in a fully reduced pressure state, the roughing is stopped, and then the exhaust port  317  is opened. 
     Subsequently, the inert gas such as He or Ar is supplied from the gas supply means, not shown, into the gas introducing flange  210  in FIG.  5 . The supplied gas passes through the pipe  206  and plate  205  as shown in FIG. 5 between the film forming chambers, and then through the punching board to the exhaust port for exhausting the gas. In this state, electric power is supplied from electric power supply means not shown to the lamp heater  233 , to start heating the substrate  234 . 
     Heating and burning are performed in this state, usually at least thirty minutes, or several hours or more, as necessary, until the temperature is sufficiently at equilibrium, and residual gas within the chamber is evacuated fully for practical use. 
     If the heating is ended, the film formation is subsequently performed. To perform the film formation, the supply of gas such as He or Ar used for heating is stopped. 
     Then, at least the film forming source gases such as SiH 4  and GeH 4  and diluent gases such as H 2 , He and Ar to be added as necessary or doping gases such as PH 3 , BF 3  and B 2 H 6  are supplied from the gas supply unit, not shown, in adjusted desired flow amounts. Such film forming gases flow through the gas discharge hole into the film forming chambers ( 236 ,  237 ), while at the same time being exhausted through the punching metal, so that the pressure can be determined from the relation between the flow and the exhaust speed, but is preferably adjusted in a range from about 1 to 100 mtorr. 
     In this state, if microwave power is applied from the microwave generator, not shown, via the applicator  244 , through the waveguide  242  into the film forming chambers ( 236 ,  237 ) and film forming space made up by the substrate  234 , a microwave discharge plasma is excited within the film forming chambers ( 236 ,  237 ), to start formation of desired deposited films on the substrate  234 . 
     If the deposited film having a desired film thickness is obtained, the supply of microwave power is stopped in order to cease the film formation. 
     Subsequently, the supply of electric power to the lamp heater is stopped to cool the system. Thereafter, the maintenance process is repeated over again. 
     Although the process was thus described, the present invention has a joint  208  having an O-ring  207  at one end of the pipe  206  for supplying the film forming gas from the vacuum chamber  201  into the film forming chamber composed of the members  236 ,  237  and the substrate  234 , whereby there is no need of disassembling or assembling the pipes in pulling out the film forming chamber from the vacuum chamber, or conversely placing back the film forming chamber into the vacuum chamber, because of the provision of the joint inserted into the sleeve  209 . 
     In pulling or pushing the film forming chamber, this joint is automatically disengaged or engaged, thus yielding extremely enhanced operability. The waveguide passage  242  is similarly constructed, or can be detached by one-touch by means of a clamp in this embodiment, although it was fixed to the applicator and the film forming chamber by means of a number of bolts and nuts, typically using ordinary waveguides, for which it took a lot of time, with poor maintenance capability. 
     Also, in a normal microwave film forming apparatus, after the individual parts secured within the vacuum chamber are taken out, cleaned and regenerated, they must be reassembled, thus requiring much maintenance time. In contrast, the present invention provides a double structure in which the detachable film forming chamber is provided within the vacuum chamber, as above described, and the connection between them can be freed by one touch, and then assembled. Thus, the maintenance operation to be effected quite rapidly. 
     In the following, a film forming apparatus using an RF system according to the present invention will be exemplified. FIG. 7 is a cross-sectional view of one chamber of the film forming apparatus for continuously forming the film on the substrate, taken along a direction perpendicular to the longitudinal direction of the film forming apparatus, typically showing the film forming chamber and the vacuum chamber making use of the RF. 
     In FIG. 7,  251  is a vacuum chamber, one face thereof being formed by a detachable flange  252 . Provided inside the flange  252  is a stay  253 , on which the film forming chamber  254  is placed detachably. Like the microwave system, the film forming gas introducing pipe is provided with a joint  255  having an O-ring for connection between the pipe on the side of the vacuum chamber and the pipe on the side of the film forming chamber  254 . The film forming gas is introduced through this joint  255 , and blown through the gas discharge hole into the film forming chamber  254 . 
     The flange  252  has a guide mechanism (not shown) as in the case with the microwave system as previously described, and can be smoothly attached or detached. A practical film forming process is substantially the same as that of the microwave system previously described, except for the following several items, and is not further explained. 
     As is the case of the microwave system, a film forming space is formed by the film forming chamber  254  and the substrate  256 . The different point from the microwave system is that discharge is excited between the cathode and the substrate by an electrode rather than applicator means, since the plasma exciting means is RF (with a radio frequency of nominally 13.56 MHz as broadly used), and exhaust means such as a mechanical booster pump is employed, since the pressure for forming the film is in a range from 0.1 to 10 torr. 
     Also in the film forming apparatus making use of the RF system, according to the present invention, the maintenance can be achieved only by allowing replacement of the film forming chamber ( 254 ), as is the case of the microwave system previously described, resulting in greatly enhanced availability factor of the apparatus. 
     An example in which a solar battery of a-SiGe single cell using an a-SiGe layer as an i-layer (photoelectric conversion layer) is fabricated, using a film forming apparatus of roll-to-roll type to which the first invention is applied, will be described below. 
     The film forming apparatus of roll-to-roll type which is applied to the manufacture of a solar cell is one of forming a plurality of layers including at least an n-type a-Si layer, an i-type a-SiGe layer and a p-type a-Si layer, making up the solar cell within the treatment rooms which are separate reaction vessels, by continuously delivering a band-like substrate for forming the a-SiGe film from a bobbin having the band-like substrate wound like a roll, this apparatus comprising a connecting member (commonly referred to as a “gas gate” or simply “gate”) for allowing the substrate to move within a plurality of film forming spaces, while maintaining the reduced pressure state within each of the film forming spaces, and having a function of preventing mutual diffusion and mixture of source gases for e.g., n-type a-Si layer and p-type a-Si layer which are supplied into the film forming chambers. 
     FIG. 8 is a typical view showing one example of a film forming apparatus of roll-to-roll type for use in fabricating an a-SiGe solar cell of the present invention. Such apparatus makes an i-type a-SiGe layer having a great thickness of deposited film and for which high throughput is required, by means of μW (microwave), and makes n-type and p-type a-Si layers having a small thickness of deposited film and for which so high throughput is not required, by RF method. 
     In FIG. 8,  801  is a band-like substrate for depositing a-Si film thereon, which is usually a deformable conductive substrate in this example, for example, a flexible plate member such as a stainless or aluminum plate, or a member having coating of a conductive thin film on a non-conductive thin plate. The band-like substrate  801  is wound around the circular bobbin  511 , and placed within a delivery room  810 . The band-like substrate  801  delivered from the bobbin placed within the delivery room  810  is passed through a gas gate (hereinafter simply referred to as a “gate”)  820 , a vacuum chamber  830  having an n-type a-Si film forming chamber internally, a gate  840 , a vacuum chamber  850  having an i-type a-Si film forming chamber internally, a gate  860 , a vacuum chamber  870  having a p-type a-Si film forming chamber internally, and a gate  880 , and then wound around a winding bobbin  891  placed within a winding chamber  890 . 
       830   a ,  870   a  are RF generators, and  830   b ,  870   b  are cathode electrodes for exciting RF discharge to which electric power for depositing n-type a-Si layer and p-type a-Si layer is supplied, respectively. 
       850  is an applicator composed of a dielectric window for radiating microwave to the discharge space, to which electric power is applied from a microwave generator, not shown, through a rectangular waveguide  550   b  placed vertically in the dielectric window, to excite glow discharge within the i-type a-SiGe film forming chamber. 
     The vessels  802  to  806  are filled with gases which are sources for forming the deposited film, wherein  802  is filled with SiH 4  gas,  803  with GeH 4  gas,  804  with H 2  gas,  805  with PH 3  gas, and  806  with B 2 H 6 , for example. 
     Those gases are led through respective shut-off valves  802  to  806  and respective pressure reducers  802  to  806  into the gas mixers  830 ,  850 ,  870 . The source gases which are mixed at desired flow amounts and mixing ratios by the gas mixers  830  to  870  are passed through the gas introducing lines  830 ,  850 ,  870  and blown into the film forming chambers. The gases introduced into the film forming chambers are exhausted by exhausters  810   e ,  830   e ,  850   e ,  870   e ,  890   e  comprised of an oil diffusion pump, a mechanical booster pump and a rotary pump, while the chamber pressures are being regulated to desired values, and led into an exhaust gas treating unit, not shown. Electric power is supplied from the power sources  830   g ,  850   g ,  870   g  for film forming chambers to the substrate heating infrared lamp heaters  830   f ,  850   f ,  870   f.    
       841 ,  860  are parts for adjusting the gate opening in cross section to reduce the mutual diffusion of gases between film forming chambers by narrowing the gas flow passage. Further, to the gate, the gas such as e.g., H 2 , or He which has no detrimental effect on the formation of film is supplied via gas inlet ports  842 ,  862  from a bomb  807  through respective pressure reducers  807 , and flow regulators  807   c ,  807   d , further preventing mutual diffusion of source gases between the film forming chambers. 
     The band-like substrate  801  delivered from the delivery chamber  810  is advanced through the film forming chambers in succession, to form an n-type a-Si film, an i-type a-SiGe film and a p-type a-Si film thereon, and finally entered into the winding chamber  890 . 
     First, in the vacuum chamber  830  containing n-type a-Si film forming chamber internally, the band-like substrate is heated by the infrared lamp heater  830  up to a desired temperature. Also, the gases such as SiH 4 , H 2 , PH 3  which are sources for the n-type a-Si film are mixed at optimal flow rates by the gas mixer  830 , and introduced into the film forming chamber. At the same time, RF power is applied from the RF generator  830   a  to the cathode  830   b , to excite glow discharge within the film forming chamber to form n-type a-Si film on the surface of the band-like substrate  801 . 
     Then, the band-like substrate  801  is advanced through the gate  840  to enter the vacuum chamber  850  having i-type a-SiGe film forming chamber internally. Within the vacuum chamber  850 , the gases of SiH 4 , GeH 4  and H 2  at optimal flow rates are supplied with optimal power to form i-type a-SiGe film on the n-type a-Si film, in the same manner as previously described. In the same manner, the band-like substrate  801  is passed through the gate  860  and the vacuum chamber  870  having p-type a-Si film forming chamber internally, and wound around the bobbin  891  within the winding chamber  890 . 
     Herein, the vacuum chambers  830 ,  850 ,  890  are provided with detachable flanges  831 ,  851 ,  871  which are characteristic of the present invention. These flanges are provided with stay guide mechanisms for supporting the film forming chambers which are detachable in a direction perpendicular to the longitudinal direction of the vacuum chamber, as already described. 
     According to the procedure as previously described, the film formation and maintenance are performed. Then, before the deposited film is exfoliated from a site other than the band-like substrate of interest, the film forming operation is stopped, the system is purged, and the exhaust valve is closed to set the inside of the system at an atmospheric pressure. 
     Thereafter, the flanges  831 ,  851 ,  871  are pulled out, and the film forming chambers are replaced with new spare parts which have been cleaned, respectively. Subsequently, a vacuum is pulled on the system, and the film formation is started again. 
     EXPERIMENT 1 
     The film formation and maintenance was performed in a case of using the above-described film forming apparatus and in a case of using the apparatus having the vacuum chamber and the film forming chamber as shown in FIG. 3 under the same film forming conditions, and the maintenance time required was compared between both cases. For the apparatus as shown in FIG. 3, it took a total of three hours and fifty minutes including, 
     Leak: 20 minutes 
     Dismounting of parts: 30 minutes 
     Regeneration of parts (blasting, etching): one hour 
     Drying of parts: one hour 
     Mounting of parts: 40 minutes 
     Pulling vacuum: 20 minutes, 
     while in the present invention (with the apparatus as shown in FIG.  8 ), it took a total of one hour including, 
     Leak: 20 minutes 
     Replacement of parts: 20 minutes 
     Pulling parts: 20 minutes 
     with a greatly enhanced availability factor of the apparatus. 
     An example of an apparatus for fabricating a solar battery of a triple cell structure composed of three p-i-ns, using the film forming apparatus of roll-to-roll type of the first invention, will be described below. 
     The configuration of solar battery comprises photoelectric conversion layers of a-SiGe on a bottom cell made by microwave method, a-SiGe on a middle cell made by microwave method, a-Si on a top cell made by RF method, or other layers made by RF method. FIG. 9 is a typical view showing an typical example of the film forming apparatus of the present invention for fabricating such solar battery. 
     In FIG. 9,  601  is a band-like substrate. The band-like substrate is SUS430 e.g. 350 mm wide and 0.15 mm thick, which has been subjected to washing and surface preparation at the previous step. The surface preparation specifically includes a coating of metal to enhance the light utilization efficiency with increased reflection, but is listed in detail in Table 1. 
     Such band-like substrate is let out from the delivery bobbin  603  placed on the delivery chamber  602  to the film forming chambers. 
     The substrate having passed through all the film forming chambers to form the films thereon is wound around the winding bobbin  605  placed within the winding chamber  604 .  611  to  623  are vacuum chambers having film forming chambers internally, all chambers, including the delivery chamber  602  and the winding chamber  604 , being connected via gas gates through which the band-like substrate can pass. 
     Also, with the increased number of chambers and the extended total length, one cannot ignore the drooping, due to gravity, of the band-like substrate, whereby all the chambers are arranged in a catenary form. 
     A flange of each vacuum chamber which is characteristic of the first invention, having a structure as shown in FIGS. 4 and 5, for example, can be removed, together with the film forming chamber, in a direction perpendicular to the longitudinal direction of the connected vacuum chambers. 
     The functions of a film forming chamber placed within each vacuum chamber are listed below. 
       611 : RF film forming chamber for bottom cell n-layer film formation 
       612 : RF film forming chamber for bottom cell n/i diffusion preventing layer film formation 
       613 : Microwave film forming chamber for bottom cell i-layer film formation 
       614 : RF film forming chamber for bottom cell i/p diffusion preventing layer film formation 
       615 : RF film forming chamber for bottom cell p-layer film formation 
       616 : RF film forming chamber for middle cell n-layer film formation 
       617 : RF film forming chamber for middle cell n/i diffusion preventing layer film formation 
       618 : Microwave film forming chamber for middle cell i-layer film formation 
       619 : RF film forming chamber for middle cell i/p diffusion preventing layer film formation 
       620 : RF film forming chamber for middle cell p-layer film formation 
       621 : RF film forming chamber for top cell n-layer film formation 
       622 : RF film forming chamber for top cell i-layer film formation 
       623 : RF film forming chamber for top cell p-layer film formation 
     EXPERIMENT 2 
     A triple cell solar battery was fabricated in practice using a film forming apparatus as shown in FIG. 9. A specific procedure thereof is the same as that of the apparatus as shown in FIG.  8  and already applied in experiment 1. Also, the film forming conditions in detail are listed in Table 1 below. Note that the conveying speed of band-like substrate was 500 mm/min. 
     The band-like substrate corresponding to one bobbin was wound around a winding bobbin, the film formation is stopped at every time the exchange of bobbin is required (hereinafter referred to as “one film forming cycle”), to perform maintenance for all the chambers by purging, cooling and leaking. 
     The exchange of i-layer film forming chambers  613 ,  618  using microwave having high film forming speed and requiring deposit of substantial film thickness was done every film forming cycle, and the exchange of other film forming chambers was done every five film forming cycles. 
     In this way, a total of ten film forming cycles were performed. From the resulting solar batteries for ten film forming cycles, i.e., ten rolls, three samples 1 cm square per roll were cut out, to which a transparent electrode (ITO) and a collector electrode (Al) were vapor deposited, whereby the solar battery conversion efficiency was evaluated under illumination of AM1. 
     The result of evaluating the characteristics for 30 sheets of samples indicated that the conversion efficiency could fall within a range from 10.58 to 10.75%. 
     The maintenance operation only involves exchanging the film forming chamber after venting the vacuum chamber, and thus can be accomplished quite rapidly, resulting in greatly reduced down-time than ever before. 
     Note that a way of shortening the cleaning time of treatment room in the film forming apparatus has been disclosed in Japanese Laid-Open Patent Application No. 62-218570, for example. 
     According to this patent, a portion requiring cleaning takes the form of a cassette, and the portion requiring cleaning is removed at the time of maintenance, and replaced with a new cassette which has been prepared and cleaned, thereby resulting in substantially shortened cleaning time. 
     That is, a plurality of cassettes are prepared, and cleaned while not in use. 
     However, the above way of shortening the treatment room cleaning time was implemented for the batch-type deposited film manufacturing apparatus, but did not refer to the application to the system of continuously forming the film on the substrate such as a roll-to-roll processing system. In particular, the film forming method or apparatus cleaning only necessary vacuum chambers while the band-like substrate remains within the vacuum chamber is unique to the present invention. 
     Where the substrate is continuously input in a vacuum processing apparatus, for example, an asher, an etcher, and a CVD system, particularly when the roll-like band-like substrate is used, to replace the substrate or the parts of treatment room, it was necessary that all the chambers including the delivery chamber and the treatment room be vented to replace the substrate and the parts because the continuous substrate is delivered. 
     To return to its original state after the so-called maintenance process, the cleaning of treatment room, the vacuum up for removing the gas or water content adsorbed to the wall face of treatment room, the pretreatment, for example, a presputter for cleaning the surface of target oxidized if the sputtering system is used, or an operation of removing attachments on the surface by heating and evaporating the evaporating material which has been oxidized if the evaporation system is used, are required, significantly decreasing the availability of the treatment device or increasing the work involved. 
     In particular, in performing the treatment in vacuum at high temperatures, a sufficient amount of time was needed to decrease the temperature by turning off the switch of the heating device, in addition to the above operation, before venting. Further, after maintenance, more time was required for heating up to high temperatures to return to its original state, often resulting in markedly degraded availability of the apparatus. 
     Specifically considering the time required in such an operation, for example, in the CVD system, it normally takes about 30 minutes to 2 hours to cool the apparatus, about 10 minutes to one hour to vent the vacuum chamber, about one hour to three hours to clean the treatment room, about one hour to five hours to increase the degree of vacuum, and about one hour to five hours to elevate the temperature, depending on the conditions or the dimensions of the individual apparatus. 
     Accumulation of such time for every vacuum chamber remarkably degrades the availability of the apparatus. These affairs are the same as those of the sputtering or etching system. 
     In Japanese Laid-Open Patent Application No. 3-30419 and Japanese Laid-Open Patent Application No. 5-251361, it was disclosed that the delivery chamber and the winding chamber for the substrate, and further the vacuum chambers having predetermined treatment rooms are only selected and set to the atmosphere, while maintaining necessary treatment rooms at predetermined degree of vacuum, using a member for partitioning between adjacent vacuum chambers with the band-like substrate pinched therein. 
     Thereby, the substrate can be replaced, and the cleaning operation of treatment room set to the atmosphere can be also effected, while maintaining the pressure and temperature within the vacuum chamber other than those set to the atmosphere in desired state. However, the cleaning time of the treatment room is not fundamentally shortened. 
     Also, for shortening the cleaning time of the treatment room in the film forming apparatus, there is a method as disclosed in Japanese Laid-Open Patent Application No. 62-218570, previously described, but none of the methods or apparatuses were suggested which can be effectively applied to the system of continuously forming the film on the substrate. 
     Thus, a second film forming apparatus of the present invention is provided with a delivery mechanism, a treatment room, and a winding mechanism within each of a plurality of vacuum chambers connected, wherein the substrate is moved from said delivery chamber to the winding chamber through the vacuum chambers having the treatment rooms to continuously treat the substrate, wherein the treatment room is detachably constructed from the vacuum chamber, and gate valves are provided to yield a pressure difference between adjacent vacuum chambers in a state where the band-like substrate is passed therethrough, and closed at the time of maintenance, with only the vacuum chambers requiring maintenance set to atmospheric pressure, whereby the detachable treatment rooms are replaced with the spare rooms, or the bobbin for the delivery mechanism or winding mechanism is replaced with a new one. 
     In the above-mentioned film forming apparatus and method, in particular, the roll-to-roll processing system, the treatment of the substrate particularly in the form of a band within the treatment room can be effected by making use of a microwave CVD method, an RFCVD method, or the microwave CVD method and RFCVD method at the same time. 
     With the roll-to-roll processing method, the band-like substrate can be continuously moved. 
     And in the above-mentioned film forming apparatus, the gate valve is comprised of a movable portion having a valve for vacuum sealing the band-like substrate on a support, the valve and the support for the movable portion being formed of e.g. an O-ring, and the band-like substrate being made movable continuously. 
     In the apparatus for continuously forming the film with the gate valves applied as above-described, only the vacuum chambers requiring maintenance can be cleaned, while the band-like substrate is left behind within the vacuum chamber, resulting in greatly shortened cleaning time for maintenance, and yielding remarkably enhanced availability of the apparatus. 
     One form of the film forming apparatus and method to which the above-mentioned gate valve is applied in the present invention will be described below. 
     In the apparatus of such a construction, the vacuum chamber having a detachable treatment room may be, for example, a chamber for treating the substrate by microwave CVD, as shown in FIG. 6, or a chamber for treating the substrate by RFCVD method, as shown in FIG.  7 . 
     FIGS. 10A and 10B are schematic views showing a gate valve (hereinafter abbreviated as a “pinch valve”) for providing a pressure difference between adjacent vacuum chambers for use with the present invention, in which FIG. 10A is a side view thereof, and (B) is a front view of a movable portion. 
     In the same figure,  324  is a housing,  322  is the movable portion,  323  is a support,  325  is a drive mechanism, and  321  is a substrate subjected to film formation. The movable portion  322  of the pinch valve has a valve section  326  for shutting off the gas and deposited unwanted matter and a valve section  327  for shutting off deposited unwanted matter which can pinch the substrate  321 , and is driven by a pinch valve driver  325  to open or close the pinch valve to provide a pressure difference therebetween. The valve section for the movable portion  322  in contact with the substrate  321  and the support  323  are formed like an O-ring, the material thereof being Byton rubber for the vacuum seal, for example. 
     In the first film forming apparatus or method of the present invention, use of a pinch valve capable of independently leaking the easily detachable treatment room and each vacuum chamber as already described allows for maintenance by selectively venting only the treatment room having large attachment of the film made by e.g. CVD method. Accordingly, the vent time can be shortened. 
     Also at the time of maintenance to be performed, the vacuum chamber which was not vented can continue to maintain a baking state, resulting in shorter heating time after maintenance. Further, since the vented chamber is limited, the time for pulling vacuum again after maintenance can be shortened. Further, another merit is that since atmospheric leak is not performed for the chambers requiring no maintenance every time after treatment, the mixture of impurities such as water, oxygen or nitrogen which cause problems in vacuum treatment can be reduced. 
     An example of a processing apparatus relying on a method of fabricating an amorphous solar battery with source gas decomposition by microwave and RF in which a film forming apparatus having a pinch valve and a detachable treatment room according to the present invention is applied to the roll-to-roll film forming apparatus, will be schematically described below. The roll-to-roll film forming apparatus which is applicable to the manufacture of the solar battery in which a plurality of layers including at least an n-type a-Si layer, an i-type a-SiGe layer and a p-type a-Si layer which constitute the solar battery are formed within treatment rooms which are separate reaction vessels by continuously delivering the band-like substrate from the bobbin around which the substrate is wound like a roll, but the substrate is made movable through the treatment rooms and supplied thereto, while maintaining a reduced pressure state in each treatment space. For example, there is provided a connecting member (commonly referred to as a “gas gate” or simply a “gate”) having a mechanism for preventing mutual diffusion or mixture of source gases for an n-type a-Si layer and a p-type a-Si layer. 
     FIG. 11 is a typical view showing an example of a film forming apparatus for use in fabricating semiconductor devices such as an a-SiGe solar battery comprising the maintenance chamber and the pinch valve. With such apparatus, the i-type a-SiGe layer having a large thickness of deposited film, for which high throughput is required, is made by μW method (microwave), while the n-type and p-type a-Si layer having small thickness of deposited film, which does not require as high a throughput as the i-type a-SiGe layer, is made by the RF method. 
     The apparatus as shown in FIG. 11 has fundamentally the same constitution as the film forming apparatus as shown in FIG.  8  and previously described (in FIG. 11, like numerals are used to indicate the same parts as in FIG.  8 ), in which the band-like substrate  801  is wound around the circular bobbin  811 , and provided within the chamber  810  having a delivery mechanism inside (hereinafter abbreviated as a “delivery chamber”). 
     The band-like substrate  801  delivered from the bobbin placed in the delivery chamber is passed through the gas gate (hereinafter abbreviated as “gate”)  820 , the vacuum chamber  830  having internally n-type a-Si film forming chamber, the gate  440 , the vacuum chamber  850  having internally i-type a-SiGe film forming chamber, the gate  800 , the chamber  870  having internally p-type a-Si film forming chamber, and the gate  880 , and wound around a winding bobbin  891  placed within the chamber having a winding mechanism (hereinafter abbreviated as a “winding chamber”). 
     And these vacuum chambers  830 ,  850 ,  870  each have a film forming chamber as a treatment room provided inside thereof detachable in a direction perpendicular to the longitudinal direction (arrangement direction) of the vacuum chamber, as shown in FIGS. 4,  5  and  7 . 
     The apparatus as shown in FIG. 11 is characterized in that the pinch valves  823 ,  843 ,  863 ,  883  are provided between chambers  810  and  830 , chambers  830  and  850 , chambers  850  and  870 , and chambers  870  and  890 , respectively. Such pinch valve is opened also during treatment such as film formation. If the treatment is ended, the valves on both sides of the chamber requiring the maintenance are closed to set only the desired chamber at atmospheric pressure. 
     In the apparatus as shown in FIG. 11, the film formation and maintenance can be made in accordance with the method for the apparatus as described in FIG.  8 . 
     The band-like substrate  801  delivered from the delivery chamber  810  is advanced through the treatment rooms in succession, formed with an n-type a-Si film, an i-type a-SiGe film, and a p-type a-Si film on the surface thereof, and finally entered into the winding chamber  490 . 
     First, the band-like substrate is heated up to a desired temperature by an infrared lamp heater within the chamber having the n-type a-Si film forming chamber. Also, the gases such as SiH 4 , H 2 , PH 3  which are sources for n-type a-Si film are mixed at respective optimal flow rates by a gas mixer  830 , a mixed gas being introduced into a vacuum chamber  830 . At the same time, RF power is applied to a cathode  830  by an RF generator  430   a , exciting a glow discharge within the treatment space to form n-type a-Si film on the surface of the band-like substrate  801 . 
     Then, the band-like substrate  801  is advanced through the gate  840  into the chamber  850  having the i-type a-SiGe film forming chamber. Within the chamber  850 , the gases such as SiH 4 , GeH 4 , H 2  set at optical flow rates are supplied with optimal power, as previously described, to form desired i-type a-SiGe film on the n-type a-Si film. 
     Similarly, the band-like substrate  801  is passed through the gate  860  and the chamber having a p-type a-Si film forming chamber and wound around the bobbin  891  within the winding chamber  890 . 
     With this apparatus, if the above treatment is ended, only the chambers requiring the maintenance are open to atmospheric pressure by closing the pinch valves  423 ,  443 ,  463 ,  483 , and the film forming chambers as detachable treatment rooms are replaced with the spare rooms, after which the pressure is reduced for subsequent treatment. 
     Specifically, the chamber  850 , the delivery chamber  810  and the winding chamber  896  are vented to atmospheric pressure by closing the pinch valves  823 ,  843 ,  863 ,  883 . And while the treatment room  850  is replaced with a spare treatment room, the bobbin for the delivery chamber  810  is replaced with a new bobbin, and the bobbin after treatment of the winding chamber  890  is taken out to install a free bobbin. 
     As above-described, the roll-to-roll film forming apparatus and method thereof having the treatment room which can be easily attached or detached, and the pinch valve, is able to have drastically enhanced availability of the apparatus, and perform superior treatment continuously. 
     EXPERIMENT 3 
     A method of fabricating a solar battery of single cell structure having a single photoelectric conversion layer, using a film forming apparatus having a detachable treatment room from the vacuum chamber and the pinch valve, will be described below. 
     The constitution of solar battery uses a photovoltaic conversion layer of a-SiGe made by microwave, and other layers made by RF. 
     A band-like substrate  801  as shown in FIG. 11 is made of SUS430BA 350 mm wide, 0.15 mm thick, and 350 m long, and has already been subjected to washing and a surface preparation in the preprocess. The surface preparation specifically includes a metallic coating for enhancing the light utilization efficiency with increased reflection. 
     The film forming conditions are listed in detail in Table 2. 
     The band-like substrate  801  is passed from the delivery bobbin  811  placed in the delivery chamber  810  through the gate  820 , n-type a-Si film forming chamber  830 , gate  840 , i-type a-SiGe film forming chamber  850 , gate  860 , p-type a-Si film forming chamber  870 , gate  880  around a winding bobbin  891  placed within the winding chamber  890 , under tension adjustment to prevent the band-like substrate  801  from slacking. 
     Then, the delivery chamber  810 , the winding chamber  890 , the film forming chambers  830 ,  850 ,  870  were exhausted by exhausters  810   e ,  830   e ,  850   e ,  870   e ,  890   e  each comprised of an oil diffusion pump, a mechanical booster pump and a rotary pump, until the pressure within each chamber reached 1 Torr. 
     Thereafter, each of the infrared lamp heaters  830   f ,  850   f ,  870   f  was lit up, and the surface temperature of the band-like substrate  801  was made 800° C. under temperature control, followed by heating and degassing. 
     When the heating and degassing was sufficiently performed, the deposited film was continuously formed under the conditions as listed in Table 2. 
     Then, the moving speed of the band-like substrate  801  was 500 mm/min. Each treatment chamber was purged and maintenance was conducted for the next process, every time the band-like substrate  801  having a length of 350 m is ended and bobbin exchange is required (hereinafter referred to as “one process cycle”). 
     In the maintenance, since the replacement of a treatment room for a-SiGe made by microwave having a high depositing rate and requiring a large thickness of the film, a delivery bobbin  811 , and a winding bobbin  891  around which the band-like substrate  801  having the deposited film formed thereon is wound is conducted at every process cycle, the a-SiGe treatment room  850 , the delivery chamber  810  and the winding chamber  890  are returned to atmospheric pressure by closing the pinch valves  823 ,  843 ,  863 ,  883 . 
     However, since other treatment rooms are maintained at every ten cycles, vacuum is retained while the heating infrared lamp heaters  830 ,  870  are lit up. 
     For the a-SiGe treatment room, the cassette having deposited film attached thereon is taken out, and replaced with a new cassette which has been prepared and cleaned, and the delivery bobbin is taken out with the band-like substrate  801  cut away about 1 mm behind, and replaced with a new bobbin around which a new band-like substrate is wound. 
     As shown in FIG. 12, the new band-like substrate  801  is rounded at the end, and welded with the existing band-like substrate  801  by spot welding ( 552 ). The bobbin  891  around which the band-like substrate having deposited film formed is wound is taken out with the band-like substrate cut away, two or three rounds left behind, and replaced with a new winding bobbin, around which the band-like substrate two or three rounds left behind is then wound. 
     If the above maintenance is ended, vacuum is pulled by the exhausters  810   e ,  850   e ,  890   e , and at the pressure equivalent to that of the treatment room retained in vacuum, the pinch valves  823 ,  843 ,  863 ,  883  are opened to restart the process. 
     The results of the availability factor of the apparatus for (a) roll-to-roll treatment with the apparatus as shown in FIG.  11  and (b) treatment with the apparatus not using the pinch valve are listed in Table 3. The availability factor is expressed as treatment time/(treatment time+rest time)×100%. 
     In (a), since the exchange of treatment room can be fulfilled in the form of cassette, the time for cleaning the treatment room and passing the band-like substrate through the apparatus, or particularly, the time for increasing vacuum by heating, because vacuum can be held by the pinch valve, where no maintenance is required, can be significantly shortened, resulting in enhanced availability of apparatus up to 81%. 
     Also, the characteristics of deposited film formed in this experiment were examined. Then samples obtained in (a) with an area of 5 cm square were cut out for every 30 m, and deposited with a transparent electrode (ITO) and a collector electrode (Al), whereby the conversion efficiency of solar battery was evaluated. The evaluation result of characteristic for ten samples indicated that the conversion efficiency could fall within a range from 7.81 to 8.03%, favorably compared with a conventional conversion efficiency of 7.95% for the sample similarly obtained in (b). 
     A method of fabricating a solar battery of triple structure having three p-i-n junctions, using a film forming apparatus to which a film forming apparatus having the pinch valve and the treatment room detachable from the vacuum chamber according to the present invention is applied, will be described below. 
     The constitution of solar battery uses a-SiGe made by microwave on the bottom cell and the middle cell, and photovoltaic conversion layer of a-Si made by RF on the top cell, and all other layers made by RF. 
     FIG. 13 is a schematic view showing a typical example of an apparatus for fabricating such a solar cell. 
     A basic constitution of the apparatus as shown in this figure is the same as that of the apparatus as shown in FIG.  9  and previously described (in FIG. 13, like numerals are used to indicate the same parts as in FIG.  9 ). 
     Note that the vacuum chambers  611  to  623 , as well as the delivery chamber  602 , and winding chamber  604  are connected via the gas gates, as shown in the figure. The gates at both ends of i-type a-SiGe treatment room made by microwave, and in the delivery chamber and the winding chamber are provided with pinch valves  631 ,  632 ,  633 ,  634 ,  635 ,  636 . 
     Also, with increased number of chambers and extended total length of apparatus, the drooping due to gravity of the band-like substrate  601  is significant and therefore all the chambers are arranged like a catenary. 
     EXPERIMENT 4 
     A solar battery having triple structure was fabricated, using an apparatus as shown in FIG. 13, according to a method as shown in FIG.  11  and under the conditions as listed in Table 1 and previously described. 
     A band-like substrate  601  is passed from a delivery bobbin  603  placed within a delivery chamber  602  through a chamber  611  having an n-type a-Si treatment room, an n/i diffusion preventing treatment room  612 , a chamber  613  having an i-type a-SiGe treatment room, a chamber  614  having an i/p diffusion preventing treatment room, a chamber  615  having a p-type a-Si treatment room, for the bottom cell; a chamber  616  having an n-type a-Si treatment room, a chamber  617  having an n/i diffusion preventing treatment room  612 , a chamber  618  having an i-type a-SiGe treatment room, a chamber  619  having an i/p diffusion preventing treatment room, a chamber  620  having a p-type a-Si treatment room, for the middle cell; and a chamber  621  having an n-type a-Si treatment room, a chamber  622  having an i-type treatment room, and a chamber  623  having a p-type a-Si treatment room, to a winding bobbin  605  placed within a winding chamber  604 , under tension adjustment to prevent the band-like substrate from slacking. Subsequently, film formation was conducted, according to the method as described in experiment 4, and under the conditions as listed in Table 1. 
     The maintenance for the chamber having a-SiGe treatment room, the delivery chamber, and the winding chamber was conducted every process cycle, while that for other treatment rooms was conducted every ten process cycles, as in experiment 3. 
     The results of comparing the availability factors for (c) roll-to-roll treatment with the apparatus as shown in FIG.  13  and (d) treatment with the apparatus not using the pinch valve for making the triple cell are listed in Table 3. 
     In (c), the number of treatment rooms to be cleaned decreases, the cleaning time, particularly the time for vacuum up can be greatly shortened, resulting in greatly enhanced availability of the apparatus up to 76%. 
     Also, the characteristics of deposited films formed in this experiment were examined. Ten samples with an area of 5 cm square were cut out for every 30 m, and deposited with a transparent electrode (ITO) and a collector electrode (Al), whereby the conversion efficiency of solar battery for triple cell was evaluated. The evaluation of characteristics for ten samples indicated that the conversion efficiency could fall within a range from 10.58 to 10.75%, favorably compared with a conventional conversion efficiency of 10.71% for the sample similarly obtained in (b). 
     In the apparatus for continuously forming the film on the substrate of the structure, as shown in FIG. 8, for example, as a result that heating and cooling of the vacuum vessel and the film forming chamber is repeated by operation and stop of the apparatus, the problems such as discharge leakage, deformation of band-like substrate, difficulty in conveying the band-like substrate, rupture, and short-circuit of rf introducing portion arise. 
     The causes for the problems such as discharge leakage, deformation of the band-like substrate, difficulty in conveying the band-like substrate, rupture, and short-circuit of rf introducing portion will be described below in due order. 
     First, when using an apparatus of roll-to-roll type as shown in FIG. 14, the possibility of discharge leakage will be described below with reference to FIGS. 15 and 16. 
     FIG. 15 is an upper view of the apparatus as shown in FIG. 14, wherein  950  is a common center line of vessels (chambers)  901  to  915  arranged in a sequence. 
     The apparatus as shown in FIG. 14 has the same fundamental structure as that shown in FIG. 9, wherein there are provided in succession a plurality of vacuum chambers  902  to  914  between the chamber  901  on the delivery side and the chamber on the winding side, through which the band-like substrate  900  is conveyed. Also, each chamber  902  to  914  has a treatment room  916  to  928  which function as a film forming room for subjecting the substrate to film formation. Each treatment room  916  to  928  forms a film forming space relative to the band-like substrate  900 . 
       931 ,  932  are a delivery axis and a winding axis, respectively, which are orthogonal to the center line  300 . Also, the center line  950  is substantially coincident with that of the band-like substrate  900 . In the apparatus of FIG. 14, the center line of all the vacuum vessels is substantially a straight line at the early stage of installation, as shown in FIG.  15 . 
     It has been found that thereafter, if the apparatus of FIG. 14 is run, or stopped for the maintenance, the center line  950  might be displaced like an S-character, due to heat history of heating and cooling, depending on the conditions. 
     As will be described later, an example of the result of observing the displacement amount of the center line  950  is graphically represented in FIG.  16 . In FIG. 16, the transversal axis is in a direction of conveying the band-like substrate  900 , with the delivery axis  931  inside a vacuum vessel (chamber)  901  as an origin, and the conveying direction of the band-like substrate  900  or the direction toward the winding axis  932  being defined positive. On the other hand, the longitudinal axis is defined positive in an upper direction from the paper face of FIG. 15, and negative in a lower direction thereof, to represent in which direction the vacuum vessel  902 ,  914  is relatively displaced with reference to the band-like substrate  900 . 
     In FIG. 16, for example, a vacuum vessel  902  (B) is relatively slightly displaced in the lower direction in the drawing of FIG. 15 to the band-like substrate, and a vacuum vessel  914  (N) is slightly displaced in the upper direction. 
     The vacuum vessels  901 ,  915  contain a conveying mechanism, but because of a weight of about 6 tons, they can not be easily moved. 
     By contrast, the vacuum vessels  902  to  914  as light as about a quarter the weight are prone to displacement, and the film forming chambers  916  to  928  contained and fastened within them are displaced by the same amount in the same direction. Owing to this displacement, the center line of the film forming chambers (treatment rooms) and the center line of the band-like substrate  900  are mismatched, resulting in a problem that a gap occurs between the band-like substrate  900  for forming the film forming chambers and the upper plate of treatment rooms  916  to  928  (e.g., a ceiling plate  102  for the chamber as shown in FIG.  2 ), causing discharge leakage. 
     Then, deformation or rupture of the band-like substrate, or difficulty in conveying the band-like substrate will be described below. 
     The discharge leakage was a problem caused by the arrangement relation between the band-like substrate  900  and the ceiling plate of each chamber, but if this displacement was further increased, a phenomenon was observed that the end portion of the band-like substrate mechanically abuts against the inner wall of the vacuum chamber or treatment room with the vacuum chamber. 
     With a slight contact force, the band-like substrate  900  may be only slightly deformed. With a greater contact force, however, a deformed portion of the band-like substrate  900  may be captured within the apparatus, making the conveyance impossible. In this state, if the tension is further increased, a problem arises that the band-like substrate will ultimately break away. 
     In the following, for the problems of short-circuit and local discharge in the RF power introducing portion, the situation that the film forming chambers are heated when the apparatus is activated, will be described, as an example, with the case of using that vacuum chamber as shown in FIG.  2 . The film forming chamber  103  is heated by a substrate heater  113 , a gas heater  114  and a plasma produced in a glow discharge space  118 . 
     As a result, insulators  111 ,  112  for supporting a feeder board  701  and a discharge electrode  104  are broken away, causing the feeder board  701  and a shield  702  to be contacted and short-circuited. Consequently, the discharge can not be maintained and stabilized, resulting in the problem that the quality of deposited film on the band-like substrate  100  is dispersed and the yield is lowered. On the other hand, if the feeder board  701  and the shield  702  are separated apart to avoid short-circuit by thermal deformation, another problem arises. 
     That problem is producing a local discharge between the feeder board  701  and the shield  702 , without exciting discharge in a desired glow discharge space (film forming space)  118 . 
     Since the electric field density between the feeder board  701  and the shield  702  is greater than that of the glow discharge space  118 , the local discharge is easily produced, depending on the condition. The condition is well known as a Paschen&#39;s law, to which no description is given herein. 
     In order to excite discharge only in the glow discharge space without producing the local discharge between the feeder board  701  and the shield  702 , the dimensions of the feeder board  701  and the spacing between the feeder board  701  and the shield  702  may be experimentally determined. 
     As above-described, some measures for avoiding the short-circuit of the feeder board  701  are necessary. 
     A second form of the present invention is that when the arrangement of vacuum vessels is displaced within a horizontal plane due to the reason of repeated heating and cooling of the film forming chambers, the positional adjustment can be made by moving the film forming chamber within the horizontal plane to eliminate the relative misregistration between the film forming chamber and the band-like substrate, thereby preventing leakage of plasma discharge, and avoiding generation of abnormal (local) discharge, and avoiding the trouble such as deformation of the band-like substrate, difficulty in conveying the band-like substrate, or rupture. 
     This will be more specifically described below with reference to the drawings. 
     As previously described in connection with FIG. 15, with the film forming apparatus of roll-to-roll type, there is a phenomenon that as a result that the vacuum vessels  901  to  915  and the film forming chambers  916  to  928  heated and cooled by repeating the heating and cooling of the apparatus, the arrangement of vacuum vessels  901  to  915  is displaced and moved in the horizontal plane. 
     The arrangement of the vacuum vessels  901  to  915  is displaced to cause the film forming chambers  916  to  928  to be relatively misaligned with the band-like substrate  900 , resulting in the problem of deforming the band-like substrate  900 , making the conveyance difficult, or leaking plasma discharge, as previously described. 
     To resolve this, the film forming chambers  916  to  928  are moved in the horizontal plane for positional adjustment so that the band-like substrate  900  may pass through the proper positions of the film forming chambers  916  to  928 . 
     However, in a vessel as shown in FIG. 2, for example, since the RF power and the source gases are introduced from the bottom face of a vacuum vessel  101  into a film forming chamber  700 , and an inlet tube between the vacuum vessel  101  and the film forming chamber  700  is fixed such that the RF power and the source gases may not leak, the film forming chamber  700  can not be moved relative to the vacuum vessel  101  in the horizontal plane. 
     In the second form of the present invention, since the RF power and the source gases are introduced into the film forming chambers through the wall faces of vacuum vessels within a vertical plane, and perpendicular to the conveying direction, the film forming chambers of the present invention can be moved in the horizontal plane, allowing for the positional adjustment such that the center of the band-like substrate may pass through the central position of the film forming chamber. 
     Within one prismatic vacuum vessel, there are two wall faces within the vertical plane and perpendicular to the conveying direction, but the RF power and the source gases may be introduced from the same face among two faces, or another face. 
     Also, since the junction for a portion for introducing the RF power and the source gases which lies outside the film forming chambers and inside the vacuum vessels is elastic, the film forming chambers of the present invention can be moved in the horizontal plane, such that only the film forming chambers can be adjusted in position without moving the vacuum vessels. 
     First, referring to FIG. 17, one form of positional adjustment for the film forming chambers  306  in a second film forming apparatus of the present invention will be described below. 
     FIG. 17 is a cross-sectional view showing the structure of vacuum vessel of the second film forming apparatus (plasma CVD film forming apparatus) according to the present invention. Like numerals are used to indicate the same parts as in FIG.  2 . The cross-section thereof is orthogonal to the conveying direction of the band-like substrate  100 , the band-like substrate being conveyed from the fore side to the rear side on the paper face. 
     In FIG. 17,  100  is a band-like substrate,  101  is a vacuum vessel,  102  is a ceiling plate,  103  is a film forming chamber,  104  is a discharge electrode,  105  is a gate electrode,  106  is a feeder board,  107  is a juncture,  108  is a shield,  109  is an rf introducing flange,  110  to  112  are insulators,  113  is a substrate heater,  114  is a gas heater,  115  is a heater supporting stay,  116  is a film forming chamber supporting stay,  117  is a position securing metal fitting,  118  is a glow discharge space,  119  is a gas introducing tube,  120  is a gas introducing flange, and  121  is an O-ring. 
     In FIG. 17, when the vacuum vessel  101  per se is misregistered 5 mm to right in the figure, for example, it follows that the band-like substrate  100  is displaced 5 mm to left in the figure relative to the film forming chamber  103 . 
     Owing to this misregistration, there occurs an interstice in the glow discharge space  118  corresponding to the film forming space, enclosed by the band-like substrate  100 , the ceiling plate  102  and the film forming chamber  103 , causing leakage of plasma, or contact between the band-like substrate  100  and the film forming chamber  103 , resulting in the problem of deforming the band-like substrate  100 . 
     One way to solve the above problem such that the band-like substrate  100  may be located in the center of the film forming chamber  103 , after the position securing metal fitting  117  is released and the film forming chamber  103  is moved 5 mm to left in the figure, the position securing metal fitting  117  is placed again. Then, the juncture  107  is subjected to compressive force, but since the juncture  107  is configured to be easily flexed by a flexible member having an elliptic cross-section, it can absorb the displacement caused by the movement of film forming chamber  103 . 
     Also, the gas introducing flange  120  secured to the vacuum vessel  101  and the gas introducing tube  119  secured to the film forming chamber  103  are of the construction having pipes of different inner diameters fitted, and slidable, thereby provided with an easily flexible structure, whereby the gas-introducing tube  119  and the gas introducing flange  120  are slidable to left and right in directions leaving apart from each other, so that the displacement due to the movement of the film forming chamber  103  can be absorbed. Also, they are slidable without leakage of source gases from the fitting portion between the gas introducing tube  119  and the gas introducing flange  120  owing to the O-ring  121 . 
     As above described, the position between the band-like substrate  100  and the film forming chamber  103  can be properly retained by moving the film forming chamber in the horizontal plane. 
     Then, while the vacuum vessel  101  of the plasma CVD system as shown in FIG. 17 is operating, the juncture  107  will be specifically described below. 
     When the apparatus is activated, the film forming chamber  103  is heated up to near 300° C. by the heater  113 , heater  114 , and plasma produced by glow discharge. 
     On the other hand, the vacuum vessel  101  is subjected to heat radiation from the film forming chamber  103 , but the temperature thereof will rise up to near 70° C., due to heat diffusion to the atmosphere or the surroundings. 
     Therefore, since the film forming chamber  103  is displaced by great heat expansion, the connecting portion between the film forming chamber  103  and the vacuum vessel  101 , in particular, the juncture  107  for joining with the feeder board  106  for supplying the RF power to the discharge electrode  104 , is subjected to compressive force. 
     The juncture  107  will be deformed elliptically in cross-section of the juncture  107  and contracted to absorb the displacement. 
     Since the juncture  107  is constructed of thin plates placed one on the other, the juncture  107  has the increased surface area, with high conductivity of rf, resulting in the enhanced efficiency of feeding power to the discharge electrode. 
     FIG. 18 is a view of the juncture for the feeder board ( 106  in FIG. 17) for the RF power. 
       270  is a juncture,  271 ,  272  are feeding boards, and  273  is a direction of the force applied on the juncture. 
     If a force is exerted in the direction of the arrow  273  in the figure, a portion of the juncture  270  almost circular in cross-section is easily deformed elliptically. In this way, by making the juncture  270  flexible, the displacement of the feeder board owing to positional adjustment of the film forming chamber, and the displacement of the feeder board due to heat expansion can be absorbed as shape changes of the juncture  270 . 
     Note that a position adjustment mechanism of the film forming chamber (treatment room) within the vacuum vessel (chamber) as above described and shown in FIG. 17 is also applicable to the film forming apparatus having a film forming chamber detachable from the vacuum vessel as shown in FIGS. 4,  5  and  7 . 
     The operation or state of each member in a film forming process for the film forming apparatus (vacuum vessel) of the form as shown in FIG. 17 will be described below. 
     The film forming chamber  103  contains a guard electrode  105 , a feeder board  106 , insulators  111 ,  112 , and a gas heater  114 . The upper face of the film forming chamber  103  is covered with the ceiling plate  102  and the band-like substrate  100 . 
     On the upper portion of the film forming chamber  103 , a substrate heater  113  is disposed. The film forming chamber  103  is connected to a gas inlet tube (not shown) from the outside, and to exhaust means (not shown) outside the film forming chamber  103 . 
     The glow discharge space  118  can be retained at desired pressure by an exhaust speed adjusting mechanism provided on this exhaust means. 
     The source gases are introduced via the gas introducing tube (not shown) into the film forming chamber  103 . The upper face of the film forming chamber  103  is covered with the ceiling plate  102  and the band-like substrate  100 , and the band-like substrate  100  is overlapped at both end portions with the ceiling plate  102 , to prevent leakage of discharge produced in the glow discharge space  118 . 
     A gas heater  114  is provided within the film forming chamber  103 , source gases introduced into the film forming chamber  103 , the discharge electrode  104  and the film forming chamber  103  per se are heated by the heater  114 . 
     On the upper portion of another film forming chamber, a substrate heater  113  is provided to heat the band-like substrate  100  to a desired film forming temperature. 
     RF power is supplied via an RF introducing flange  109 , a connecting portion  107  and a power feeding portion  106  into the discharge electrode  104 . 
     The film forming chamber  103  is supported by the film forming chamber support stay  116 , and normally secured by a position securing metal fitting  117 , but when the position securing metal fitting  117  is loosened, the film forming chamber  103  is movable to left and right in the figure. 
     The connecting portion  107  is flexible to left and right in the figure, such that the position of the film forming chamber  103  can be adjusted in the horizontal direction, in particular to left and right. 
     The glow discharge space  118  is a space enclosed by the wall face of the film forming chamber  103 , discharge electrode  104 , band-like substrate  100  and ceiling plate  102 , the band-like substrate  100  is supported by a magnet roller (not shown) and conveyed in front and back directions on the paper face. 
     The source gases introduced into the glow discharge space  118  are subjected to dissociation by RF power applied between the discharge electrode  104  and the band-like substrate  100 , so that the semiconductor film can be continuously deposited on the band-like substrate  100 . 
     The second film forming apparatus of the present invention uses vacuum vessels containing a film forming chamber of the form as shown in FIG. 17, and was applied to, for example, a plasma CVD system of the roll-to-roll type having the structure as shown in FIG.  14 . If the apparatus is activated, the band-like substrate  900  (substrate  100  in FIG. 17) is successively formed with desired semiconductor layers in a plurality of film forming chambers  916  to  928 , while being continuously conveyed in its longitudinal direction at a constant speed. Finally, the semiconductor layers are laminated on the band-like substrate  900 , so that desired semiconductor junction devices can be formed consecutively. 
     As a result, semiconductor junction devices of large area can be mass produced. 
     In the following, the experimental results made based on the above-described embodiment will be described below, with specific numeric values given. 
     EXPERIMENT 5 
     In a plasma CVD system of roll-to-roll type as shown in FIG. 14, for a case (sample e) where a solar battery of triple cell structure having three pins was fabricated via a film forming process of forming the films on the band-like substrate by the system, using a vacuum vessel  101  having a film forming chamber  103  and a juncture  107 , as shown in FIG. 17, for each of the vacuum vessels  902  to  914 , with the positional adjustment of the film forming chamber  103  during the film forming process, and a case (sample f) where a solar battery of triple structure was fabricated in the same manner by forming the films on the band-like substrate, using the system with vacuum vessels having a film forming chamber  700  as shown in FIG. 2, without positional adjustment of the film forming chamber  700  during the film forming process, the characteristics of the triple cell fabricated were evaluated and compared. 
     The film forming conditions adopted are listed in Table 5. In FIG. 14, for convenience sake, the vacuum vessels  901  to  915  are indicated by A to O in this order. The sorts of semiconductor layers formed in the vacuum vessels B to N are n-type layers for B, G, and L, n/i buffer layers for C, and H, i-type layers for D, I, and M, p/i buffer layers for E, and J, and p-type layers for F, K, and N. 
     First, the experiment of a sample f will be specifically described below. As shown in FIG. 15, at the early stage of installation, the vacuum vessels  901  to  915  were arranged linearly along a center line  950 . 
     In this system, the film formation was conducted with an apparatus (as shown in FIG. 14) having the vacuum vessels as shown in FIG. 2, and under the film forming conditions as listed in Table 5. If a band-like substrate having a total length of one lot of 780 m, is conveyed at a conveying speed of 1270 m/min, continuous film formation for about ten hours for one lot can be effected. After this film formation was repeated for ten lots, there was seen a phenomenon that the arrangement of vacuum vessels was displaced relatively in width direction of the band-like substrate  100 . This displacement amount measured for each of the vacuum vessels is graphically represented in FIG.  16 . The longitudinal axis indicates the displacement amount in a direction perpendicular to the conveying direction of vacuum vessels on the center line  950  as previously described and shown in FIG. 15, and the transversal axis indicates the position of each vacuum vessel in the conveying direction. 
     In FIG. 15, if the vacuum vessels  901  to  915  are displaced in a width direction of the band-like substrate  930  (substrate  100  in FIG.  2 ), the misregistration of the band-like substrate  930  relative to the film forming chambers  916  to  928  takes place. In this state, when making a triple cell by the film formation with that apparatus, there was seen a phenomenon that the interstice occurred in the glow discharge spaces in some of the film forming chambers  916  to  928 , during film formation, so that plasma leaks to the outside of the film forming chambers. 
     Further, on the triple cell structures were formed by vapor deposition a transparent electrode and a collector electrode, thereby completing a solar battery. The evaluation of the resulting solar battery was made by measuring the photoelectric conversion efficiency η when illuminating with artificial sunlight having an AM value of 1.5 and an energy density of 100 mW/cm 2 , as shown in FIG.  2 . The photoelectric conversion efficiency η of the solar battery having an area of 0.25 cm 2  in the central portion and both end portions of the band-like substrate (the band-like substrate  100  of FIG. 2) in the width direction is listed in Table 6. Note that the end portion  1  is a right end of the band-like substrate and the end portion  2  is a left end thereof in FIG.  2 . 
     An experiment for sample e will be specifically described below. The internal constitution of a vacuum vessel for an apparatus for fabricating the sample is shown in FIG. 19, the film forming chamber being adjustable in position within the horizontal plane. To eliminate the interstice of the glow discharge space caused by displacement of the vacuum vessel in a film forming process under the conditions as listed in Table 5, the position of the chamber  927  within the vacuum vessel  913  was corrected so that the center of the film forming chamber  927  may be aligned with the center of the band-like substrate  930  in FIG. 15, for example, the central line of the film forming chamber  927  may be arranged along the central line  950 . In FIG. 17, the position of the film forming chamber  103  was corrected within the vacuum vessel  101 . 
     Specifically, in FIG. 17, where the vacuum vessel  101  was offset 5 mm to the right in the figure from a predetermined position, a position securing metal fitting  117  was loosened to move the film forming chamber  103  to the left by 5 mm, to correct the center of the film forming chamber  103  to be aligned to the center of the band-like substrate  100 . 
     Then, a compressive force is exerted on the juncture  107 , but since the juncture is easily flexible, its displacement due to movement of the film forming chamber  103  can be absorbed, without modification of parts for the juncture. 
     Since a gas introducing tube  119  and a gas introducing flange  120  are slidable to left and right in the figure, the displacement due to movement of the film forming chamber  103  could be absorbed. 
     Note that the displacement of the vacuum vessel  101  to the left in FIG. 17 corresponds to a positive displacement in the chart as shown in FIG.  15 . 
     Also, the maximum movable amount of the fitting portion of the juncture  107  and the gas introducing tube  119  with the gas introducing flange  120  is ±10 mm in this example, so that even with a vacuum vessel  910  (J) having the maximum displacement amount measured for e.g. a sample as shown in FIG. 15, the positional adjustment of the film formation chamber  924  can be effected. 
     As above-described, the positional adjustment of the film forming chamber  103  was made, using a vessel as shown in FIG. 17, and the film formation was conducted under the film forming conditions as listed in Table 5. On a structure of triple cell formed, a transparent electrode and a collector electrode were formed by vapor deposition, thereby completing a solar battery. The results of measuring the photoelectric conversion efficiency η, like the sample e, are listed in Table 6. 
     As will be clear from the results of Table 6, sample f has a non-uniform distribution of characteristics in the width direction of the band-like substrate, while sample e of the present invention has more uniform distribution of characteristics. 
     EXPERIMENT 6 
     A solar battery of a-Si single cell structure was fabricated, using a plasma CVD system of roll-to-roll type having a structure as shown in FIG.  15 . An experiment for measuring the time for which the stable discharge can be sustained was repeated ten times, while the system was continuously operated for ten hours at maximum, whereby comparison was made between a case (sample j) where a solar battery was fabricated using the system comprising vacuum vessels with a juncture  107  having the structure as shown in FIG. 17, and a case (sample h) where a solar battery using the system having the structure of a film forming chamber  700  as shown in FIG.  2 . 
     Note that all the layers were formed by RF plasma CVD in this experiment. 
     The film forming conditions for this experiment were listed in Table 7. 
     The RF power used had an oscillating frequency of 13.56 MHz. The film forming chamber  505  in the vacuum vessel  501  was deposited with an n-type layer, the film forming chamber  506  in the vacuum vessel  502  with an i-type layer, and the film forming chamber  507  in the vacuum vessel  503  with a p-type layer. 
     The heater temperature in Table 7 is a temperature of heater  114  in FIGS. 2 and 17. 
     The apparatus was operated under the film forming conditions to form a single cell. As a result of repeating a continuous operation of the apparatus ten times for a case of making a sample g and a case of making a sample h, the average time when three discharges of the glow discharge spaces  511  to  513  as shown in FIG. 11 were stably sustained is listed in Table 8. 
     In a process of making a sample h, if the time has elapsed from the excitation of discharge, the trouble such as extinction of discharge or increased reflection power arose, while when making the sample g, the discharge was always stable. 
     Further, on the single cell structure formed, the transparent electrode and the collector electrode were formed by vapor deposition to complete a solar battery. 
     The evaluation of the solar battery formed was performed by measuring the photoelectric conversion efficiency η when illuminating with the artificial sunlight having an AM value of 1.5 and an energy density of 100 mw/cm 2 . 
     For the central portion of the band-like substrate  100  in the width direction, the photoelectric conversion efficiency η of the solar battery having an area of 0.25 cm 2  is listed in Table 8. 
     As will be clear from the above results, in experiment 6, the discharge of the glow discharge spaces  511  to  513  could be stably operated continuously over ten hours, thereby stably forming pin-type photovoltaic elements of large area. 
     A first form of the present invention resides in taking out and removing the treatment room such as a film forming chamber from the vacuum chamber in the apparatus for continuously forming the film on the substrate, wherein the maintenance capability and the availability of the apparatus can be greatly enhanced, with reduced costs of the apparatus, by exchanging only the film forming chamber, with a simple operation of taking out and removing the film forming chamber from the vacuum chamber, without spending much time to clean away the powder or film. 
     Also, in the first form of the present invention, the film forming chamber is connected via a joint having an O-ring with the gas supply portion for supplying this film forming gas, and when the film forming chamber is taken out from the vacuum chamber, or conversely, restored into the vacuum chamber, it can be automatically connected therewith by pulling or pushing, resulting in greater workability. 
     Further, the film forming chamber is coupled via a connection clamp with an applicator with which electric power is introduced via the power introducing waveguide provided on the side of the film forming chamber into the waveguide provided on the side of the flange in the vacuum chamber, so that the film forming chamber can be pulled out from the vacuum chamber by one touch, resulting in further enhanced maintenance capability. 
     In the first form of the present invention, since the treatment room can be detached from the vacuum chamber, and a pressure difference between adjacent vacuum chambers can be provided in the state where the band-like substrate is passed through a plurality of vacuum chambers, the gate valve is closed at the time of maintenance, the detachable treatment room can be replaced with a spare room, with the vacuum chamber which requires maintenance being set at atmospheric pressure, or the bobbin for the delivery mechanism or winding mechanism can be replaced with a new one, thereby greatly reducing the maintenance time particularly in the film forming apparatus of roll-to-roll type, and enhancing the availability of the apparatus, with consequent reduced costs of the product. 
     A second form of the present invention, in the apparatus for continuously forming the film on the substrate, by constructing the introducing portion for RF power and the source gases flexible in one vacuum chamber, when the vacuum vessel is displaced relatively in a horizontal plane, for the reason of repeated heating and cooling of the treatment room such as film forming chamber within the vacuum chamber, the positional adjustment can be made by moving the film forming chamber in the horizontal plane, to eliminate the relative misregistration between the film forming chamber and the band-like substrate, thereby preventing leakage of plasma discharge, and avoiding generation of abnormal (local) discharge, whereby a uniform and homogeneous functional deposited film for the photovoltaic element can be manufactured. 
     Also, with the above constitution, a functional deposited film for the photovoltaic element can be manufactured with good yield, while avoiding the trouble such as deformation of the band-like substrate, difficulty in conveying the band-like substrate or rupture. 
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
             
            
               
                   
                 Substrate 
                 SUS430BA 
                 350 mm wide 
                 0.15 mm 
               
               
                   
                   
                   
                   
                 thick 
               
               
                   
                 Reflection 
                 Silver (Ag) 
                 Thin film 
               
               
                   
                 layer 
                   
                 100 nm 
               
               
                   
                 Reflection 
                 Zinc gas flow (ZnO) 
                 Thin film 
               
               
                   
                 augmenting 
                   
                 1 μm 
               
               
                   
                 layer 
               
               
                   
                 Gate gas 
                 H 2  from each gate 
                 1000 cc/min 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
            
               
                   
                   
                   
                   
                   
                 Temperature 
               
               
                   
                   
                 Used gas flow 
                 Discharge 
                 Pressure 
                 of substrate 
               
               
                   
                 Layer name 
                 (cc/min) 
                 power (W) 
                 (Torr) 
                 (° C.) 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Layer 
                 n-type 
                 SiH 4   
                 100 
                 100 (RF) 
                 1.0 
                 290 
               
               
                 fabrication 
                 semiconductor 
                 PH 3 /H 2  (1% diluted 
                 500 
               
               
                 conditions 
                 layer 
                 H 2   
                 700 
               
               
                   
                 n/i diffusion 
                 SiH 4   
                 50 
                 50 (RF) 
                 1.1 
                 270 
               
               
                   
                 preventing 
                 H 2   
                 1000 
               
               
                   
                 layer 
               
               
                   
                 i-type 
                 SiH 4   
                 50 
                 200 
                 0.02 
                 310 
               
               
                   
                 semiconductor 
                 GeH 4   
                 50 
                 (microwave) 
               
               
                   
                 layer 
                 H 2   
                 300 
               
               
                   
                 p/i diffusion 
                 SiH 4   
                 20 
                 50 (RF) 
                 1.1 
                 280 
               
               
                   
                 preventing 
                 GeH 4   
                 7 
               
               
                   
                 layer 
                 H 2   
                 1000 
               
               
                   
                 p-type 
                 SiH 4   
                 100 
                 1000 RF) 
                 1.0 
                 175 
               
               
                   
                 semiconductor 
                 BF 3 /H 2  (1% diluted) 
                 50 
                   
               
               
                   
                 layer 
                 H 2   
                 1500 
               
               
                   
                 n-type 
                 SiH 4   
                 50 
                 50 (RF) 
                 1.0 
                 270 
               
               
                   
                 semiconductor 
                 BF 3 /H 2  (1% diluted) 
                 500 
               
               
                   
                 layer 
                 H 2   
                 1000 
               
               
                   
                 n/i diffusion 
                 SiH 4   
                 50 
                 50 (RF) 
                 1.1 
                 250 
               
               
                   
                 preventing 
                 H 2   
                 1000 
               
               
                   
                 layer 
               
               
                   
                 i-type 
                 SiH 4   
                 45 
                 180 
                 0.015 
                 290 
               
               
                   
                 semiconductor 
                 GeH 4   
                 40 
                 (microwave) 
               
               
                   
                 layer 
                 H 2   
                 300 
               
               
                   
                 p/i diffusion 
                 SiH 4   
                 20 
                 50 (RF) 
                 1.1 
                 280 
               
               
                   
                 preventing 
                 GeH 4  (1% diluted) 
                 5 
               
               
                   
                 layer 
                 H 2   
                 1000 
               
               
                   
                 p-type 
                 SiH 4   
                 100 
                 1000 (RF) 
                 1.0 
                 175 
               
               
                   
                 semiconductor 
                 PH 3 /H 2  (1% diluted) 
                 500 
               
               
                   
                 layer 
                 H 2   
                 1500 
               
               
                   
                 n-type 
                 SiH 4   
                 100 
                 80 (RF) 
                 1.0 
                 270 
               
               
                   
                 semiconductor 
                 PH 3 /H 2  (1% diluted) 
                 120 
               
               
                   
                 layer 
                 H 2   
                 1500 
               
               
                   
                 i-type 
                 SiH 4   
                 150 
                 400 (RF) 
                 1.1 
                 200 
               
               
                   
                 semiconductor 
                 H 2   
                 1000 
               
               
                   
                 layer 
               
               
                   
                 p-type 
                 SiH 4   
                 10 
                 1000 (RF) 
                 1.0 
                 175 
               
               
                   
                 semiconductor 
                 BH 3 /H 2  (1% diluted) 
                 50 
               
               
                   
                 layer 
                 H 2   
                 2500 
               
            
           
           
               
               
               
               
            
               
                   
                 Transparent 
                 ITO (In 2  + SnO 2 ) 
                 Thin film 
               
               
                   
                 electrode 
                   
                 100 nm 
               
               
                   
                 Collector 
                 Aluminum (Al) 
                 Thin film 
               
               
                   
                 electrode 
                   
                 2 μm 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
             
            
               
                   
                 Substrate 
                 SUS430BA 
                 300 mm wide 
                 0.2 mm 
               
               
                   
                   
                   
                   
                 thick 
               
               
                   
                 Reflection 
                 Silver (Ag) 
                 Thin film 
               
               
                   
                 layer 
                   
                 100 nm 
               
               
                   
                 Reflection 
                 Zinc oxide (ZnO) 
                 Thin film 
               
               
                   
                 augmenting 
                   
                 1 μm 
               
               
                   
                 layer 
               
               
                   
                 Gate gas 
                 H 2  from each gate 
                 500 cc/min 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
            
               
                   
                   
                 Used gas flow 
                 Discharge 
                 Pressure 
                 Temperature of 
               
               
                   
                 Layer name 
                 (cc/min) 
                 power (W) 
                 (Torr) 
                 substrate (° C.) 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Layer 
                 n-type 
                 SiH 4   
                 100 
                 100 (RF) 
                 1 
                 270 
               
               
                 fabrication 
                 layer 
                 PH 3 /H 2  (1% diluted 
                 500 
               
               
                 conditions 
                   
                 H 2   
                 700 
               
               
                   
                 i-type 
                 SiH 4   
                 50 
                 200 
                 0.02 
                 360 
               
               
                   
                 layer 
                 GeH 4   
                 50 
                 (microwave) 
               
               
                   
                   
                 H 2   
                 200 
               
               
                   
                 p-type 
                 SiH 4   
                 100 
                 1000 (RF) 
                 1.0 
                 150 
               
               
                   
                 layer 
                 BF 3 /H 2  (1% diluted) 
                 50 
               
               
                   
                   
                 H 2   
                 1500 
               
            
           
           
               
               
               
               
            
               
                   
                 Transparent 
                 ITO (In 2  + SnO 2 ) 
                 Thin film 
               
               
                   
                 electrode 
                   
                 100 nm 
               
               
                   
                 Collector 
                 Aluminum (Al) 
                 Thin film 
               
               
                   
                 electrode 
                   
                 2 μm 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 3 
               
               
                   
                   
               
             
            
               
                   
                 Items 
                 (b) 
                 (a) 
                 Unit 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Treatment 
                 10.0 
                 10.0 
                 Time 
               
               
                   
                 Rest Time 
                 9.1 
                 2.3 
                 Time 
               
               
                   
                 Breakdown 
               
               
                   
                 Leak 
                 0.4 
                 0.2 
               
               
                   
                 Cooling of 
                 1 
                 0.5 
               
               
                   
                 apparatus 
               
               
                   
                 Cleaning of 
                 2.5 
                 0.5 
               
               
                   
                 treatment room 
               
               
                   
                 Pulling vacuum 
                 0.2 
                 0.1 
               
               
                   
                 Vacuum up by 
                 5.0 
                 1.0 
               
               
                   
                 heating 
               
               
                   
                 Availability factor 
                 52 
                 81 
                 % 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 4 
               
               
                   
                   
               
             
            
               
                   
                 Items 
                 (b) 
                 (a) 
                 Unit 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Treatment 
                 10.0 
                 10.0 
                 Time 
               
               
                   
                 Rest Time 
                 12.1 
                 3.1 
                 Time 
               
               
                   
                 Breakdown 
               
               
                   
                 Leak 
                 1.5 
                 0.2 
               
               
                   
                 Cooling of 
                 1.5 
                 0.5 
               
               
                   
                 apparatus 
               
               
                   
                 Cleaning of 
                 3.5 
                 0.7 
               
               
                   
                 treatment room 
               
               
                   
                 Pulling vacuum 
                 0.5 
                 0.2 
               
               
                   
                 Vacuum up by 
                 5.0 
                 1.5 
               
               
                   
                 heating 
               
               
                   
                 Availability factor 
                 45 
                 76 
                 % 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 5 
               
               
                   
                   
               
             
            
               
                   
                 Substrate 
                 SUS430BA 
                 350 mm wide 
                 0.127 mm 
               
               
                   
                   
                   
                   
                 thick 
               
               
                   
                 Reflection 
                   
                 Silver (Ag) 
                 Thin film 
               
               
                   
                 layer 
                   
                   
                 50 nm 
               
               
                   
                 Reflection 
                   
                 Zinc Oxide (ZnO) 
                 Thin film 
               
               
                   
                 augmenting 
                   
                   
                 1 μm 
               
               
                   
                 layer 
               
               
                   
                 Gate gas 
                   
                 H 2  from each gate 
                 1000 cc/min 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
            
               
                   
                   
                   
                   
                   
                 Temperature 
               
               
                   
                   
                 Used gas flow 
                   
                 Pressure 
                 of substrate 
               
               
                   
                 Layer name 
                 (cc/min) 
                 Discharge power (W) 
                 (Torr) 
                 (° C.) 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Layer 
                 n-type 
                 SiH 4   
                 100 
                 100 (RF) 
                 1.0 
                 290 
               
               
                 fabrication 
                 layer 
                 PH 3 /H 2  (1% diluted 
                 400 
               
               
                 conditions 
                   
                 H 2   
                 700 
               
               
                   
                 n/i buffer 
                 SiH 4   
                 50 
                 50 (RF) 
                 1.05 
                 270 
               
               
                   
                 layer 
                 H 2   
                 1000 
               
               
                   
                 i-type 
                 SiH 4   
                 50 
                 150 
                 0.01 
                 300 
               
               
                   
                 layer 
                 GeH 4   
                 50 
                 (microwave) 
               
               
                   
                   
                 H 2   
                 200 
               
               
                   
                 p/i buffer 
                 SiH 4   
                 20 
                 50 (RF) 
                 1.05 
                 280 
               
               
                   
                 layer 
                 GeH 4   
                 7 
               
               
                   
                   
                 H 2   
                 1000 
               
               
                   
                 p-type 
                 SiH 4   
                 100 
                 1200 (RF) 
                 1.0 
                 175 
               
               
                   
                 layer 
                 BF 3 /H 2  (1% diluted) 
                 50 
                   
               
               
                   
                   
                 H 2   
                 2000 
               
               
                   
                 n-type 
                 SiH 4   
                 50 
                 50 (RF) 
                 1.0 
                 270 
               
               
                   
                 layer 
                 BF 3 /H 2  (1% diluted) 
                 500 
               
               
                   
                   
                 H 2   
                 1500 
               
               
                   
                 n/i buffer 
                 SiH 4   
                 50 
                 50 (RF) 
                 1.05 
                 250 
               
               
                   
                 layer 
                 H 2   
                 1000 
               
               
                   
                 i-type 
                 SiH 4   
                 45 
                 150 
                 0.015 
                 290 
               
               
                   
                 layer 
                 GeH 4   
                 40 
                 (microwave) 
               
               
                   
                   
                 H 2   
                 300 
               
               
                   
                 p/i buffer 
                 SiH 4   
                 20 
                 50 (RF) 
                 1.05 
                 280 
               
               
                   
                 layer 
                 GeH 4   
                 5 
               
               
                   
                   
                 H 2   
                 1000 
               
               
                   
                 p-type 
                 SiH 4   
                 100 
                 1200 (RF) 
                 1.0 
                 175 
               
               
                   
                 layer 
                 PH 3 /H 2  (1% diluted) 
                 500 
               
               
                   
                   
                 H 2   
                 2000 
               
               
                   
                 n-type 
                 SiH 4   
                 100 
                 80 (RF) 
                 1.0 
                 270 
               
               
                   
                 layer 
                 PH 3 /H 2  (1% diluted) 
                 120 
               
               
                   
                   
                 H 2   
                 1500 
               
               
                   
                 i-type 
                 SiH 4   
                 150 
                 400 (RF) 
                 1.2 
                 250 
               
               
                   
                 layer 
                 H 2   
                 1000 
               
               
                   
                 p-type 
                 SiH 4   
                 10 
                 1500 (RF) 
                 1.0 
                 175 
               
               
                   
                 layer 
                 BH 3 /H 2  (1% diluted) 
                 50 
               
               
                   
                   
                 H 2   
                 4000 
               
            
           
           
               
               
               
               
            
               
                   
                 Transparent 
                 ITO (In 2  + SnO 2 ) 
                 Thin film 
               
               
                   
                 electrode 
                   
                 100 nm 
               
               
                   
                 Collector 
                 Aluminum (Al) 
                 Thin film 
               
               
                   
                 electrode 
                   
                 2 μm 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
             
               
                   
                 TABLE 6 
               
             
            
               
                   
                   
               
               
                   
                 Photoelectric conversion efficiency η 
               
            
           
           
               
               
               
               
            
               
                   
                   
                 Central 
                   
               
               
                   
                 End portion 1 
                 portion 
                 End portion 2 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 Sample e 
                 12.1% 
                 12.0% 
                 12.1% 
               
               
                   
                 Sample f 
                 12.3% 
                 12.0% 
                 11.3% 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
             
               
                   
                 TABLE 8 
               
               
                   
                   
               
               
                   
                 Discharge 
                   
               
               
                   
                 duration (average 
                 Optical photoelectric 
               
               
                   
                 value of 10 
                 efficiency η (average value 
               
               
                   
                 times) 
                 of 10 times) 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 Sample g 
                 10 hours 
                 5.6% 
               
               
                   
                 Sample h 
                 3.5 hours 
                 5.5% 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
             
               
                   
                 TABLE 7 
               
               
                   
                   
               
             
            
               
                   
                 Substrate 
                 SUS430BA 
                 300 mm wide 
                 0.2 mm 
               
               
                   
                   
                   
                   
                 thick 
               
               
                   
                 Reflection 
                 Silver (Ag) 
                 Thin film 
               
               
                   
                 layer 
                   
                 100 nm 
               
               
                   
                 Reflection 
                 Zinc Oxide (ZnO) 
                 Thin film 
               
               
                   
                 augmenting 
                   
                 1 μm 
               
               
                   
                 layer 
               
               
                   
                 Gate gas 
                 H 2  from each gate 
                 500 cc/min 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                   
                   
                   
                   
                 Temperature 
                 Temperature 
               
               
                   
                   
                 Used gas flow 
                 Discharge 
                 Pressure 
                 of substrate 
                 of heater 
               
               
                   
                 Layer name 
                 (cc/min) 
                 power (W) 
                 (Torr) 
                 (° C.) 
                 (° C.) 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Layer 
                 n-type 
                 SiH 4   
                 100 
                 100 (RF) 
                 1.0 
                 270 
                 300 
               
               
                 fabric- 
                 layer 
                 PH 3 /H 2  (1% diluted 
                 700 
               
               
                 ation 
                   
                   
               
               
                 condi- 
                   
                 H 2   
                 1000 
               
               
                 tions 
               
               
                   
                 i-type 
                 SiH 4   
                 50 
                 200 
                 1.2 
                 230 
                 300 
               
               
                   
                 layer 
                 GeH 4   
                 50 
                 200 (RF) 
               
               
                   
                   
                 H 2   
                 200 
                 200 
               
               
                   
                 p-type 
                 SiH 4   
                 10 
                 2000 RF) 
                 1.0 
                 150 
                  70 
               
               
                   
                 layer 
                 BF 3 /H 2  (1% diluted) 
                 100 
               
               
                   
                   
                 H 2   
                 1000 
               
            
           
           
               
               
               
               
            
               
                   
                 Transparent 
                 ITO (In 2  + SnO 2 ) 
                 Thin film 
               
               
                   
                 electrode 
                   
                 100 nm 
               
               
                   
                 Collector 
                 Aluminum (Al) 
                 Thin film 
               
               
                   
                 electrode 
                   
                 2 μm