Gas supply device for precursors with a low vapor pressure

[0001] [Technical field to which the invention belongs] The present invention relates to a gas supply device for a precursor having a low vapor pressure, which is described in the writing section in the premise of claim 1, particularly a gas supply device for a CVD-Beschichtungsanlage. [0002] [Conventional technology] In the latest CVD (Chemical Vapor Deposition) film forming apparatus (chemical vapor deposition deposition apparatus), a special thin film is always formed on a member or a substrate. In this case, the thin film, which can be composed of a laminate of several different thin layers, must meet the extremely high requirements for its properties. Remarkably high demands are placed on the quality of sediments to obtain these properties. This includes, for example, deposition parameters such as deposition rates that have a significant effect on membrane quality. In the case of the CVD deposition method, this deposition rate is determined decisively by the partial pressure of the gaseous precursor, so this partial pressure must be adjusted very accurately and its variation is unacceptable. [0003] A special film material is used for film formation, which is brought into the film formation equipment by the precursor of choice. Especially TiO as this precursor₂/ SiO₂Titanium tetrachloride (TiCl) for the production of alternating multilayer films₄) Or Hexamethyldisiloxane (HDMSO), which under standard conditions have a low vapor pressure well below atmospheric pressure. This low vapor pressure is usually too small to obtain sufficient deposition rates as required in industrial deposition. Therefore, this precursor must first be heated to the first evaporation temperature in the storage vessel, which results in a sufficiently high vapor pressure. [0004] In order to suppress the condensation of the precursor in the path to the film forming apparatus, the gas supply device must be heated from the storage container to the film forming apparatus to a second temperature higher than the first evaporation temperature. [0005] In addition, the material TiCl that forms the precursor or film₄, And hexamethyldisiloxane may be intermediately stored in the intermediate reservoir at a vapor pressure of approximately 50 mbar or higher so that they have a sufficiently high mass flow rate (mass flow) through subsequent valves, mass flow controllers and piping systems. Are known. In order to achieve such partial pressure, the interim storage facility is TiCl.₄Is heated to at least 50 ° C, or to hexamethyldisiloxane to 30 ° C. [0006] In addition, Nb has the advantage of less tendency to crystallize.₂O₂/ SiO₂Alternating multilayer films can also be manufactured. In addition, NbO₂Can be deposited at a relatively high deposition rate. In addition, Nb₂O₅The expansion coefficient of TiO₂More than the expansion coefficient of SiO₂Better fits to the coefficient of expansion of, resulting in Nb₂O₅Can be used to produce thicker alternating multilayer films. However, Nb₂O₅For the production of thin films, the precursors HMDSO and TiCl under standard conditions₄Only precursors with even lower vapor pressures that are well below their vapor pressure can be used. NbCl, the Nb compound with the highest vapor pressure on the market₅Presents a vapor pressure of 50 mbar for the first time at a temperature of about 170 ° C. NbCl₅The temperature dependence of the vapor pressure of is shown by the lower curve in FIG. NbCl₅The gas supply device for a homogeneous supply of steam-based PICVD film formation equipment must therefore maintain this temperature. [0007] Gas supply devices for providing low vapor pressure precursors with storage vessels for precursors and intermediate storage for mixing and buffering the vaporized precursor with other gases are known. (Japanese Patent Laid-Open No. 2-250977). The storage container is temperature controlled to the first temperature T1 and the interim storage is temperature controlled to the second temperature T2, where the first temperature T1 is lower than the second temperature and is therefore intermediate. Precursor condensation in the reservoir is avoided. A carrier gas is introduced into the storage vessel, which transports the precursor into the interim storage facility and from there into the reaction chamber. The gas supply device can be provided with a second storage vessel, from which the second precursor is introduced into the interim storage with carrier gas, resulting in two precursors. And the carrier gas are mixed with each other. In the case of this device, the interim storage facility and the device connected to it must be kept at a high temperature T2, so that the cooling time required for maintenance work is wasted and the material used. And the equipment must withstand the high temperature T2. [0008] A gas supply device for a low vapor pressure precursor in which the storage container for the precursor is held at the first temperature, particularly a gas supply device for a PICVD film forming apparatus, is prior art and is known (Germany). Patent Invention No. 4236324). Further, the gas supply device has an interim storage for intermediate storage of the vapor state precursor, which is connected to the storage container via a gas conduit. From this interim storage facility, the gas containing the precursor can be taken out from the PICVD film forming apparatus. In the case of this gas supply device, the interim storage unit is held at a second temperature, which is higher than the first temperature of the storage container. With this interim storage, pressure fluctuations in the precursor-bearing gas are significantly compensated for through removal into the PICVD film forming apparatus with different mass flow rates. [0009] However, due to the maintenance work and repairs that should be performed regularly in the interim storage facility, the interim storage facility and the gas supply and extraction equipment connected to it must be cooled at a considerable waste of time. This also requires the use of an expensive high temperature-mass flow control device for the interim storage. Furthermore, the continuous removal of the maximum precursor mass flow rate is limited by the evaporation rate of the storage vessel held at a lower temperature. [0010] [Problems to be Solved by the Invention] An object of the present invention is that maintenance work and repair work in the interim storage facility can be easily and quickly performed, and there is no need to limit the maximum achievable mass flow rate of the precursor, and the interim storage facility and its constituent members The purpose is to further improve the gas supply for precursors with low vapor pressure so that more advantageous components can be used. [0011] [Means for solving problems] This problem is solved by the feature portion according to claim 1. [0012] According to claim 1, the gas supply device according to the present invention for a precursor having a low vapor pressure includes a storage container for storing the first precursor having a low vapor pressure and a first precursor evaporated from the storage container. It has an intermediate storage section for intermediate storage of the body, a first gas conduit connecting the storage container and the intermediate storage section, and a second gas conduit for taking out gas from the intermediate storage section. This gas supply device is also referred to as a gas generator in this embodiment. [0013] The storage container is held at the first temperature T1. The gas reaches the second interim storage facility through the first conduit, where it is held at the second temperature T2. Similarly, the pressure in the interim storage is held at a constant pressure p2, which is lower than the pressure p1 in the storage vessel, so the first precursor in the vapor state is due to the higher pressure in the storage vessel. Then, it flows into the interim storage facility. According to the present invention, the first temperature T1 in the storage container is higher than the second temperature T2 in the interim storage. [0014] The removal of gas through the second gas conduit on the side of the interim storage facility is used to supply the first gaseous precursor to the film forming apparatus. The film forming apparatus is particularly a CVD film forming apparatus or the like. The precursor is also commonly referred to as the raw material (Eduktspezies), starting material or film forming material. Precursors with low vapor pressure (precursors with low vapor pressure) are interpreted as solid or liquid film-forming compounds, which have a vapor pressure of less than 10 mbar at a temperature of 50 ° C. are doing. [0015] Here, the storage container is usually a quartz flask, a special container, or something similar, in which case the container material is resistant to reaction with the precursor. The interim storage facility can be similarly formed from quartz, special steel, or the like. The interim storage facility is preferably designed to have a large capacity in order to buffer pressure fluctuations when gas is irregularly taken out from the interim storage facility. The optimum capacity of the interim storage facility is known from German Patent Invention No. 4236324, and the disclosure contents are incorporated in the present specification. [0016] The maximum mass flow rate that can be removed from the storage vessel depends on the pressure p1. In normal operation, the gas capacity of the storage vessel is filled with pure precursor vapor, so the pressure p1 is the same as the equilibrium vapor pressure of the precursor. It increases with temperature T1. The maximum amount of precursor mass flow that can be removed from the interim storage for the film forming equipment is limited by the flow of material (Stoffstrom) between the storage and the interim storage. Therefore, an increase in temperature T1 and thereby an increase in pressure p1 increases the maximum available mass flow rate for film formation. [0017] The evaporation rate of the first precursor in the storage vessel depends on the temperature T1 and the partial pressure of the first precursor in the storage vessel. This evaporation rate increases as the temperature rises. When the vaporized precursor is removed from the interim storage, the precursor is replenished very quickly due to evaporation. The saturated vapor pressure of the precursor in the storage vessel is substantially maintained. Since this saturated vapor pressure is extremely dependent on temperature (see FIG. 2), a slight change in temperature T1 can significantly change the pressure p1. [0018] Since the pressure p2 in the interim storage is even lower, the precursors are only present in the interim storage in a preferably gaseous state, so the maximum retrievable mass flow rate within a suitable temperature interval (Temperatur interval) is the interim storage. It is not limited by the smaller temperature T2 within some suitable temperature interval of the part. This temperature T2 can therefore be selected independently of the temperature T1, and the interim storage and the equipment connected to this interim storage need only have heat resistance to the smaller temperature T2. This makes it possible to use inexpensive components such as mass flow control devices and valves. For maintenance or repair work on the interim storage facility, the waiting time for the interim storage facility and the equipment connected to it to cool down is thus reduced. [0019] In addition, the lower temperature T2, which must maintain a large interim storage, helps save energy. On the other hand, the storage container can be assumed to have a smaller size than the interim storage facility, and can be incorporated in the heating region of the interim storage facility in a heat-insulated state. [0020] The temperature T2 of the interim storage is preferably adjusted so that the maximum partial pressure of the first precursor in the interim storage is lower than the saturated vapor pressure of this precursor in the interim storage at temperature T2. .. This prevents the first precursor from condensing and being left behind in the interim storage facility. [0021] [0021] If the pressure p1 is greater than or equal to 1.5 times the pressure p2 in the interim storage, a pressure gradient between the storage and the interim storage is obtained, where the connection between the storage and the interim storage is blocked. Will be. At this time, the transport speed depends positively on the differential pressure (p1-p2) and the conductance of the conduit connection between the storage container and the interim storage facility. Ideally In the extreme case of blocked flow, the maximum material flow is simply determined by p1 and the opening area of the conductive part at the blocking part (Verblockung) (eg, conduit end or valve opening). [0022] By blocking in this way, it is also avoided that the precursor vapor enters the storage container from the interim storage facility in reverse by diffusion. When a gas mixture of precursor vapor and other gas is used in the interim storage, it is avoided that the precursor in the storage vessel mixes with other gas. [0023] When a valve is used, for example, between the interim storage and the storage vessel to regulate the mass flow rate, its conductance depends only on the mass flow rate on the inlet pressure p1 and on the outlet pressure p2. It can be adjusted to be irrelevant (blocking condition) (Bedingungen der Verblockung). The pressure p1 is preferably twice as high as the pressure p2. [0024] In a preferred embodiment of the gas supply device, a regulated supply device is provided between the storage container and the interim storage unit. This regulated supply device is used to regulate the mass flow rate from the storage container to the interim storage facility. In this case, the adjustment supply device is usually a nozzle for limiting the opening area of the conductive portion, a valve for opening and closing, a throttle valve whose cross-sectional area can be changed, and the like. This regulated feeder is used to limit the mass flow from the storage container to the interim storage. Preferably, the regulated supply device increases the mass flow rate when the pressure in the interim storage is below a constant pressure p2, and when the pressure in the interim storage is above p2, for example by the regulator. Is controlled to decrease. [0025] This first regulated supply device can be controlled by a control unit or regulator on the one hand and controllable mass flow control so that the mass flow rate flowing between the storage container and the interim storage can be measured on the other hand. It is preferably a device. [0026] According to another embodiment of the gas supply device, the gas is discharged from the interim storage facility to the gas outlet via the second regulated supply device. As a result, the gas can be continuously discharged from the interim storage facility. In addition, the second regulated supply device is controlled so that gas can be discharged from the interim storage facility when the pressure exceeds p2 in order to keep the pressure in the interim storage facility constant. This outlet can also be used for exhaust and cleaning of the interim storage. [0027] The second regulated supply device may preferably be a throttle valve, in the case of such a throttle valve, the cross-sectional area for gas release is adjusted. [0028] According to other embodiments, the gas outlet is connected to a vacuum pump and / or a cold trap. This vacuum pump exhausts the discharge side of the gas outlet to a pressure below the pressure p2 of the intermediate storage so that a pressure gradient can be generated and the gas can be discharged. Also, the vacuum pump and cold trap can be used together so that the condensable gas freezes in the cold trap and the non-condensable gas is expelled from the vacuum pump. By using a cold trap, the precursors are reused, so that most expensive precursors with relatively low vapor pressure can be recovered. [0029] In a particularly preferred embodiment of the gas supply device, the carrier gas is supplied into the first gas conduit between the storage container and the interim storage. The carrier gas can be an inert gas, a second precursor, or a gas mixture containing the second precursor. In the case of a CVD process, the carrier gas is used to more quickly transport the precursor to the object to be filmed and to carry out reaction products or impurities from it. This carrier gas thus transfers the first precursor through the gas supply device more quickly. In this case, by mixing the first precursor and the carrier gas, the partial pressure of the first precursor in the interim storage is reduced below the total pressure p2 in the interim storage through the dilution of the first precursor. The additional advantageous effect of doing so is obtained. As a result, the temperature T2 of the interim storage facility can be further lowered. This is because the condensation of the precursor depends only on the partial pressure of the first precursor, not the total pressure in the interim storage. By reducing the partial pressure in the interim storage, the temperature T2 can be further reduced. This temperature T2 is limited to a lower limit such that the temperature-dependent saturated vapor pressure exceeds the partial pressure of the first precursor in the interim storage, thereby avoiding condensation. [0030] In the case of this embodiment, the mixture is stored in the interim storage, and the precursor concentration (for example, mole fraction) is adjusted to be constant. This is ensured by adjusting the ratio between the two inflowing gas streams (precursor and transport gas / reaction gas) to be constant. By placing the above-mentioned blocking part (Verblockung) between the storage container and the interim storage part, a predetermined mass flow rate from the storage container to the interim storage part is guaranteed at a constant pressure p1. Further, this blocking portion can prevent the gas mixture from flowing back by diffusion from the interim storage portion into the storage container. [0031] Since the carrier gas is actually supplied downstream of the first regulated supply device, the mass flow rate flowing through this regulated supply device contains only the precursor, and the carrier gas is supplied due to the pressure gradient through the regulated supply device. Does not flow into the storage container. [0032] In the case of other embodiments, the carrier gas is supplied via a third regulated supply device, which is preferably a mass flow control device, so that the mass flow rate of the carrier gas can be adjusted. [0033] In a particularly preferred embodiment, the mass flow rate of the carrier gas is adjusted proportionally to the mass flow rate of the first precursor from the storage vessel to the interim storage. As a result, in the interim storage facility, the mixing ratio of the first precursor and the carrier gas given in advance by the proportional factor is determined. A constant mixing ratio within the interim storage allows a tightly defined supply of the first precursor to the film forming apparatus, which in turn achieves a uniform deposition rate. [0034] To make an optically functional thin film with a niobium oxide thin film, the first precursor is an Nb compound, preferably NbCl.₅Alternatively, Nb alcoholate is used, and the carrier gas is preferably O.₂Is said to be. For example, SiO₂/ Nb₂O₅When manufacturing alternating multilayer films, O in the interim storage₂And NbCl₅With the gas mixture of Nb, there is no need to use another gas as a carrier gas.₂O₅The reaction gas for depositing the thin film can be used as it is. [0035] For thin films containing tantalum, TaCl₅Alternatively, Ta alcoholate can be preferably used. For thin films containing titanium or aluminum, TIPT (titanium-isopropilate) or AlCl₃Can be preferably used. [0036] BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, examples of the present invention will be described in detail with reference to the drawings. [0037] In the lower curve of the graph in Figure 1, NbCl₅The temperature-dependent transition of the saturated vapor pressure of is shown. Niobium pentoxide (NbCl)₅) Exists as a solid over the indicated temperature range, which sublimates directly into the gas phase. The lower curve of this graph shows NbCl in the gas phase in equilibrium with the solid phase.₅Represents the saturated vapor pressure at which the partial pressure of At 50 ° C, this saturated vapor pressure is about 0.04 mbar. This pressure is applied to NbCl in the gaseous state through the pipeline and valves of the gas supply system.₅Too small to achieve sufficient mass flow rate. In order to provide a sufficient amount of gas and to carry this amount of gas through the piping system, the temperature as well as the saturated vapor pressure must be increased. [0038] The upper curve in Figure 1 is NbCl₅NbCl until the percentage of₅Shows maximum adjustable total or absolute pressure when diluted with other gases. This total pressure is NbCl₅Starts condensing from this gas mixture NbCl₅It is about 20 times higher than the saturated vapor pressure of. [0039] Figure 2 shows the precursor NbCl in storage container 2.₅Is illustrated in the gas supply device 1 in which is stored. The evaporation of this precursor creates a first pressure p1 in the storage vessel 2. The storage container 2 is connected to the interim storage unit 4 via a first gas conduit 3. In the first gas conduit 3, the first shutoff valve 5 and the mass flow control device 6 (MFC) are arranged in order from the storage container 2. The first gas conduit 3 is shut off from the storage vessel 2 by the first shutoff valve 5, so that the storage vessel 2 is for maintenance work or the precursor NbCl.₅Can be removed from the gas supply device 1 for additional pouring. [0040] During the gas supply operation, the first mass flow rate control device 6 is used to measure the mass flow rate from the storage container 2 to the intermediate storage unit 4 and adjust the mass flow rate to a predetermined value. [0041] Another gas conduit is branched from the first gas conduit 3 between the first shutoff valve 5 and the first mass flow control device 6, and the other gas conduit is the second shutoff valve 7. It is blocked by. When the shutoff valve 7 is opened and the shutoff valve 5 is opened, the storage container 2 is exhausted by the pump 8. Similarly, the supplied purge gas (this supply portion is not shown) is discharged via the pump 8. [0042] Another conduit opens in the first gas conduit 3 between the first mass flow control device 6 and the interim storage unit 4. A second mass flow control device 9 is arranged in this conduit. By the second mass flow control device 9, the carrier gas or oxygen (O in this embodiment) into the first gas conduit 3₂) Is introduced. This results in the precursor NbCl₅Is mixed with the carrier gas and introduced into the interim storage facility 4. [0043] The gas or gas mixture can be taken out from the interim storage facility 4 through the second gas conduit 10 and supplied to the gas exchange station 11. Upon exiting the interim storage facility 4, the second gas conduit 10 has a first regulated supply valve 12 and a third shutoff valve 13 before the second gas conduit 10 reaches the depositor 14. Have been placed. When the third shutoff valve 13 is opened, the first regulated supply valve 12 creates a pressure difference between the interim storage facility 4 and the outlet side of the first regulated supply valve 12. [0044] From the interim storage facility 4, another gas conduit is drawn out through the throttle valve 15, and the other gas conduit is similarly connected to the pump 8. The pressure in the interim storage unit 4 is measured by the pressure sensor 16. The measured pressure value is supplied to the pressure regulator 17, which controls the throttle valve 15. The pressure regulator 17 maintains the pressure in the interim storage facility 4 at a predetermined second pressure value p2. When the pressure in the intermediate reservoir 4 exceeds a predetermined second pressure value p2, the pressure regulator 17 opens the throttle valve 15 and adjusts the throttle valve 15 to discharge an excess amount of gas to the pump 8. To do. [0045] In the gas exchange station 11, another gas conduit is selectively introduced from another gas conduit into the second gas conduit 10 through the fourth shutoff valve 18 behind the third shutoff valve 13. Can be done. In this embodiment, this other deposited gas is SiO₂Hexamethyldisiloxane / oxygen-mixture (HMDSO / O) for depositing thin films₂). Thus, by switching between the shutoff valve 13 and the shutoff valve 18, (precursor NbCl)₅By) Nb₂O₅From the deposition of SiO₂Can be switched to depositing. [0046] The gas supply device 1 is divided into two temperature zones. The first temperature zone is the storage area 19, which is the storage container 2, the first shutoff valve 5, a part of the first gas conduit 3, the first mass flow control device 6, the second. It has a shutoff valve 7 and a part of the supply and exhaust gas conduits. This storage area 19 is kept constant at the first temperature T1. This heating is performed by a conventional heating technique. This temperature is preferably kept constant by the regulator. The first precursor (in this case NbCl) in the storage vessel by the first temperature T1₅) Saturated vapor pressure p1 is generated. Heating of the member connected to the storage container 2 avoids condensation in the storage area 19. [0047] Further, the intermediate storage area 20 is a part of the first gas conduit 3, an intermediate storage part 4, a part of the second gas conduit 10, a first throttle valve 12, a pressure sensor 16, a throttle valve 15, and the case. Some have gas conduits for cleaning or other gas supply, which are held at a second temperature T2. [0048] In the case of the present embodiment, oxygen is supplied into the first gas conduit 3 by the second mass flow control device 9. With proper control of the mass flow controller 6 and the mass flow controller 9, the second mass flow controller 9 introduces the mass flow of oxygen in proportion to the first mass flow controller 6. become. Oxygen mass flow is NbCl₅It is 19 times the mass flow of. As a result, NbCl in the interim storage facility 4₅A mixing ratio of 5% gas to 95% oxygen is achieved. This interim storage is held at a total pressure of 40 mbar. At this time, NbCl in the interim storage facility₅The partial pressure of is about 2 mbar, which is clearly below the saturated vapor pressure of 4 mbar at 120 ° C (see Figure 1), NbCl.₅Condensation is avoided. [0049] The first temperature T1 is equal to 200 ° C, so NbCl₅The saturated vapor pressure of is to have a value of about 105 mbar according to FIG. 1, so p1 is around 100 mbar. At this time, the pressure difference between the storage container 2 and the interim storage unit 4 is more than doubled, which guarantees the mass flow from the storage container 2 into the interim storage unit 4. [0050] The adjustment of the pressure p2 in the interim storage 4 is performed by the throttle valve 15. In the mass flow control device, a constant flow rate is adjusted at that time. Apart from this, the pressure adjustment with respect to p2 is to variably control the mass flow rate of the mass flow rate controllers 6 and 9 at a certain ratio in a fixed adjusted opening section of the throttle valve 15 to the pump 8. Also done by. [0051] Further pressure reduction is performed through the first throttle valve 12 between the interim storage and the gas exchange station. This will result in NbCl₅The partial pressure of the gas exchange station is further reduced, and the temperature in the region of the gas exchange station can be further reduced. At this time, the temperature was 75 ° C, and as a result, according to Fig. 1, NbCl₅The maximum partial pressure of can have a value of 0.25 mbar, so the total pressure of the gas mixture can be up to 5 mbar. Thus, from the interim storage facility 20 to the gas exchange station 11, the pressure drops by at least one-eighth. During this pressure drop, some blocking occurs in the first throttle valve 12. That is, during this pressure drop, the mass flow rate through the first throttle valve depends only on its conductance and the pressure p2 in the intermediate reservoir 4, not on the pressure in the gas exchange station 11. The need for additional mass flow control devices to maintain a constant mass flow rate from the interim storage facility 4 to the gas exchange station 11 and further to the deposition device 14 is thus eliminated. This mass flow rate is determined by the constant pressure p2 and the regulated conductance of the first throttle valve. [0052] In another embodiment of the gas supply device, the first mass flow control device 6 can be replaced with a throttle valve corresponding to the first throttle valve 12. This is because the pressure drop between the storage container 2 and the interim storage unit 4 is more than doubled here. This replaces the high temperature-mass flow control device 6 with a suitable throttle valve. [0053] The gas supply device 1 described above is, for example, NbCl as a precursor.₅And although only the case of using oxygen as the carrier gas has been described, other precursors with low vapor pressure and other carrier gases can be used as well. Examples of this precursor are niobium ethoxydo, aluminum trichloride, titanium isopropoxide, tantalum ethoxydo. The temperature T1 to be set for the storage region 19, the temperature T2 for the intermediate storage region 20, and the temperature T3 for the gas exchange station are individual with reference to the saturated vapor pressure curve of each precursor. It can be determined while considering the concentration (mole fraction). [0054] FIG. 3 shows a multi-chamber film forming apparatus 14, 14 ́, which alternates two different precursors from the gas supply apparatus 19, 20; 19 ́, 20 ́ via the gas exchange station 11. It can be supplied for the production of multilayer films. The reference numerals given in FIG. 2 above are also used for the same members in FIG. [0055] Two gas supply devices 19,20; 19 ́,20 The function of ́ is roughly the same as that of the gas supply device 1 in FIG. 2, except that the temperature T1 of the storage region 19 and the temperature T2 of the intermediate storage region 20 are dependent on the temperature dependence of the precursor in the storage container 2. Optimized and the temperature T4 in the storage area 19 ́ and the temperature T5 in the intermediate storage area 20 ́ are relative to the temperature dependence of the vapor pressure of the second precursor in the storage container 2 ́. It is optimized. [Simple explanation of drawings] [Fig. 1] NbCl₅It is a graph which shows the temperature dependence of the saturated vapor pressure of a precursor. FIG. 2 is a diagram showing an embodiment of a gas supply device together with a gas exchange station and a CVD deposition device. FIG. 3 is a diagram showing a combination of two gas supply devices including two film forming devices connected to each other via a gas exchange station. [Explanation of symbols] 1 Gas supply device 2 Storage container 3 ... 1st gas conduit 4 Interim storage 5 1st shutoff valve 6 ... 1st mass flow control device (1st adjustment supply device) 7 2nd shutoff valve 8 Pump 9 ... 2nd mass flow control device (3rd adjustment supply device) 10 Second gas vessel 11 Gas exchange station 12 1st aperture valve 13 Third shutoff valve 14 Sedimentation device 15 Squeeze valve (second adjustment supply device) 16 Pressure sensor 17 Pressure regulator 18 4th shutoff valve 19 Storage area 20 Interim storage area