Patent Publication Number: US-2023151486-A1

Title: Raw material supply system

Description:
TECHNICAL FIELD 
     The present disclosure relates to a raw material supply system. 
     BACKGROUND 
     There is known a technique in which, after a solid raw material is dissolved in a solvent and sprayed into a processing chamber, the interior of the processing chamber is heated to remove the solvent so that a solid raw material remains, and then the processing chamber is heated to sublimate the solid raw material and to produce a corresponding gas (see, for example, Patent Document 1). 
     PRIOR ART DOCUMENT 
     Patent Document 
     
         
         
           
             Patent Document 1: Japanese Laid-Open Patent Publication No. 2004-115831 
           
         
       
    
     The present disclosure provides a technique capable of controlling an amount of a solution or a dispersion stored in a storage part. 
     SUMMARY 
     A raw material supply system according to an aspect of the present disclosure includes: a first storage part configured to store a solution obtained by dissolving a first solid raw material in a solvent or a dispersion obtained by dispersing the first solid raw material in the solvent; a second storage part configured to store the solution or the dispersion transported from the first storage part; a detection part configured to detect an amount of the solution or the dispersion stored in the first storage part; and a heating part configured to heat a second solid raw material formed by removing the solvent from the solution or the dispersion stored in the second storage part. 
     According to the present disclosure, it is possible to control an amount of a solution or a dispersion stored in a storage part. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1     1  is a view illustrating a raw material supply system according to a first embodiment. 
         FIG.  2    is a first view for explaining an operation of the raw material supply system of the first embodiment. 
         FIG.  3    is a second view for explaining the operation of the raw material supply system of the first embodiment. 
         FIG.  4    is a third view for explaining the operation of the raw material supply system of the first embodiment. 
         FIG.  5    is a fourth view for explaining the operation of the raw material supply system of the first embodiment. 
         FIG.  6    is a view illustrating a raw material supply system according to a second embodiment. 
         FIG.  7    is a view illustrating a raw material supply system according to a third embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, non-limitative exemplary embodiments of the present disclosure will now be described with reference to the accompanying drawings. In all the accompanying drawings, the same or corresponding members or components will be denoted by the same or corresponding reference numerals, and redundant explanations thereof will be omitted. 
     First Embodiment 
     (Raw Material Supply System) 
     A raw material supply system of a first embodiment will be described with reference to  FIG.  1   .  FIG.  1    is a view illustrating the raw material supply system according to the first embodiment. 
     The raw material supply system  1  is a system that produces a reactive gas obtained by sublimating a second solid raw material formed by removing a solvent from a solution obtained by dissolving a first solid raw material in the solvent (hereinafter, also simply referred to as “solution”), and performs film formation in a processing apparatus by using the produced reactive gas. 
     The first solid raw material is not particularly limited, but may be, for example, an organic metal complex containing a metal element such as strontium (Sr), molybdenum (Mo), ruthenium (Ru), zirconium (Zr), hafnium (Hf), tungsten (W), aluminum (Al) or the like, or a chloride containing a metal element such as tungsten (W), aluminum (Al) or the like. The solvent may be any material, for example, hexane, as long as it can dissolve or disperse the first solid raw material to form a solution. 
     The raw material supply system  1  may include a raw material source  10 , a buffer apparatus  20 , raw material supply apparatuses  30  and  40 , a processing apparatus  50 , and a control device  90 . 
     The raw material source  10  supplies a solution M 1  to the buffer apparatus  20 . In the present embodiment, the raw material source  10  includes a tank  11  and a float sensor  12 . The tank  11  is filled with the solution M 1 . The float sensor  12  detects an amount of the solution M 1  filled in the tank  11 . 
     One end of a pipe L 1  is inserted into the raw material source  10  from above the tank  11 . The other end of the pipe L 1  is connected to a source G 1  of a carrier gas. The carrier gas is supplied from the source G 1  into the tank  11  via the pipe L 1 . The carrier gas is not particularly limited, but may be, for example, an inert gas such as nitrogen (N 2 ), argon (Ar) or the like. A valve V 1  is provided in the pipe L 1 . When the valve V 1  is opened, the carrier gas is supplied from the source G 1  to the raw material source  10 . When the valve V 1  is closed, the supply of the carrier gas from the source G 1  to the raw material source  10  is cut off. In addition, the pipe L 1  may be provided with a flow rate controller (not illustrated) for controlling a flow rate of the carrier gas flowing through the pipe L 1 , an additional valve, and the like. 
     One end of a pipe L 2  is inserted into the raw material source  10  from above the tank  11 . The other end of the pipe L 2  is connected to the buffer apparatus  20 . When the carrier gas is supplied into the tank  11  from the source G 1 , the interior of the tank  11  is pressurized, and the solution M 1  in the tank  11  is supplied to the buffer apparatus  20  via the pipe L 2 . Valves V 2   a  and V 2   b  are provided in the pipe L 2  in order from the side of the raw material source  10 . When the valves V 2   a  and V 2   b  are opened, the solution M 1  is supplied from the raw material source  10  to the buffer apparatus  20 . When the valves V 2   a  and V 2   b  are closed, the supply of the solution M 1  from the raw material source  10  to the buffer apparatus  20  is cut off. The pipe L 2  may be provided with a flow rate controller (not illustrated) for controlling a flow rate of the solution M 1  flowing through the pipe L 2 , an additional valve, and the like. 
     One end of the pipe L 3  is connected to the side of the buffer apparatus  20  rather than the valve V 2   b  of the pipe L 2 . The other end of the pipe L 3  is connected to a source G 3  of a carrier gas. The carrier gas is supplied from the source G 3  to the buffer apparatus  20  via the pipes L 3  and L 2 . The carrier gas is not particularly limited, but may be, for example, an inert gas such as N 2 , Ar or the like. A valve V 3  is provided in the pipe L 3 . When the valve V 3  is opened, the carrier gas is supplied from the source G 3  to the buffer apparatus  20 , and when the valve V 3  is closed, the supply of the carrier gas from the source G 3  to the buffer apparatus  20  is cut off. In addition, the pipe L 3  may be provided with a flow rate controller (not illustrated) for controlling a flow rate of the carrier gas flowing through the pipe L 3 , an additional valve, and the like. 
     The buffer apparatus  20  stores the solution M 1  transported from the raw material source  10 . In the present embodiment, the buffer apparatus  20  includes a container  21  and a float sensor  22 . Further, the buffer apparatus  20  may include a heating part (not illustrated) such as a heater that heats the container  21 . The container  21  temporarily stores the solution M 1  transported from the raw material source  10 . The float sensor  22  detects an amount of the solution M 1  stored in the container  21 . However, instead of the float sensor  22 , another level sensor, such as a load cell type level sensor or a temperature detection type level sensor, may be provided to detect the amount of the solution M 1  stored in the container  21 . 
     The buffer apparatus  20  is connected to the raw material supply apparatus  30  via pipes L 4  and L 5 , and supplies the solution M 1  to the raw material supply apparatus  30  via the pipes L 4  and L 5 . Valves V 4  and V 5  are provided in the pipes L 4  and L 5 , respectively. When the valves V 4  and V 5  are opened, the solution M 1  is supplied from the buffer apparatus  20  to the raw material supply apparatus  30 , and when the valves V 4  and V 5  are closed, the supply of the solution M 1  from the buffer apparatus  20  to the raw material supply apparatus  30  is cut off. The pipe L 5  may be provided with a flow rate controller (not illustrated) for controlling a flow rate of the solution M 1  flowing through the pipe L 5 , an additional valve, and the like. 
     The buffer apparatus  20  is connected to the raw material supply apparatus  40  via the pipe L 4  and a pipe L 6 , and supplies the solution M 1  to the raw material supply apparatus  40  via the pipes L 4  and L 6 . A valve V 6  is provided in the pipe L 6 . When the valves V 4  and V 6  are opened, the solution M 1  is supplied from the buffer apparatus  20  to the raw material supply apparatus  40 , and when the valves V 4  and V 6  are closed, the supply of the solution M 1  from the buffer apparatus  20  to the raw material supply apparatus  40  is cut off. The pipe L 6  may be provided with a flow rate controller (not illustrated) for controlling a flow rate of the solution M 1  flowing through the pipe L 6 , an additional valve, and the like. 
     The raw material supply apparatus  30  stores the solution M 1  transported from the buffer apparatus  20 . In the present embodiment, the raw material supply apparatus  30  includes a container  31 , a heating part  32 , and a pressure gauge  33 . The container  31  stores the solution M 1  transported from the buffer apparatus  20 . The heating part  32  heats a solid raw material (hereinafter referred to as a “second solid raw material M 2 ”) formed by removing the solvent from the solution M 1 , thereby sublimating the second solid raw material M 2  to produce a reactive gas. The heating part  32  may be, for example, a heater disposed so as to cover a bottom portion and an outer periphery of the container  31 . The heating part  32  is configured to be able to heat the interior of the container  31  to a temperature capable of sublimating the second solid raw material to produce the reactive gas. The pressure gauge  33  detects an internal pressure of the container  31 . The detected internal pressure of the container  31  is transmitted to the control device  90 . The control device  90  controls opening/closing operations of various valves based on the detected internal pressure. For example, when the detected internal pressure becomes higher than a predetermined pressure, the control device  90  closes the valve V 5  to prevent the excess solution M 1  from being supplied to the container  31 . 
     One end of a pipe L 8  is inserted into the raw material supply apparatus  30  from above the container  31 . The other end of the pipe L 8  is connected to a source G 7  of a carrier gas via a pipe L 7 . The carrier gas is supplied from the source G 7  into the container  31  via the pipes L 7  and L 8 . The carrier gas is not particularly limited, but may be, for example, an inert gas such as N 2 , Ar or the like. Valves V 8   a  and V 8   b  are provided in the pipe L 8  in order from the side of the source G 7 . When the valves V 8   a  and V 8   b  are opened, the carrier gas is supplied from the source G 7  to the raw material supply apparatus  30 , and when the valves V 8   a  and V 8   b  are closed, the supply of the carrier gas from the source G 7  to the raw material supply apparatus  30  is cut off. A flow rate controller F 7  for controlling a flow rate of the carrier gas flowing through the pipe L 7  is provided in the pipe L 7 . In the present embodiment, the flow rate controller F 7  is a mass flow controller (MFC). 
     The raw material supply apparatus  30  is connected to the processing apparatus  50  via pipes L 10  and L 12 , and supplies the reactive gas to the processing apparatus  50  via the pipes L 10  and L 12 . Valves V 10   a  to V 10   c  are provided in the pipe L 10  in order from the side of the raw material supply apparatus  30 . When the valves V 10   a  to V 10   c  are opened, the reactive gas is supplied from the raw material supply apparatus  30  to the processing apparatus  50 , and when the valves V 10   a  to V 10   c  are closed, the supply of the reactive gas from the raw material supply apparatus  30  to the processing apparatus  50  is cut off 
     One end of a pipe L 13  is connected between the valve V 10   a  and the valve V 10   b  of the pipe L 10 . The other end of the pipe L 13  is connected between the valve V 8   a  and the valve V 8   b  of the pipe L 8 . The pipe L 13  functions as a bypass pipe that connects the pipe L 8  and the pipe L 10  without interposing the raw material supply apparatus  30 . A valve V 13  is provided in the pipe L 13 . When the valve V 13  is opened, the pipe L 8  and the pipe L 10  communicate with each other, and when the valve V 13  is closed, the communication between the pipe L 8  and the pipe L 10  is cut off 
     One end of a pipe L 14  is connected between the valve V 10   b  and the valve V 10   c  of the pipe L 10 . The other end of the pipe L 14  is connected to an exhaust apparatus (not illustrated) such as a vacuum pump. A valve V 14  is provided in the pipe L 14 . When the valve V 14  is opened in a state in which the valves V 10   a  and V 10   b  are opened, the interior of the container  31  is exhausted so that the solvent can be removed from the solution M 1  stored in the container  31 . When the valve V 14  is closed, the removal of the solvent from the solution M 1  stored in the container  31  can be stopped. 
     The raw material supply apparatus  40  stores the solution M 1  transported from the buffer apparatus  20 . The raw material supply apparatus  40  is provided in parallel with the raw material supply apparatus  30 . In the present embodiment, the raw material supply apparatus  40  includes a container  41 , a heating part  42 , and a pressure gauge  43 . The container  41  stores the solution M 1  transported from the buffer apparatus  20 . The heating part  42  heats the second solid raw material M 2  formed by removing the solvent from the solution M 1 , thereby sublimating the second solid raw material M 2  to produce a reactive gas. The heating part  42  may be, for example, a heater disposed so as to cover a bottom portion and an outer periphery of the container  41 . The heating part  42  is configured to be able to heat the interior of the container  41  to a temperature capable of sublimating the second solid raw material M 2  to produce the reactive gas. The pressure gauge  43  detects an internal pressure of the container  41 . The detected internal pressure of the container  41  is transmitted to the control device  90 . The control device  90  controls opening/closing operations of various valves based on the detected internal pressure. For example, when the detected internal pressure becomes higher than a predetermined pressure, the control device  90  closes the valve V 6  to prevent the excess solution M 1  from being supplied to the container  41 . 
     One end of the pipe L 9  is inserted into the raw material supply apparatus  40  from above the container  41 . The other end of the pipe L 9  is connected to the source G 7  via the pipe L 7 . The carrier gas is supplied from the source G 7  into the container  41  via the pipes L 7  and L 9 . The carrier gas is not particularly limited, but may be, for example, an inert gas such as N 2 , Ar or the like. Valves V 9   a  and V 9   b  are provided in the pipe L 9  in order from the side of the source G 7 . When the valves V 9   a  and V 9   b  are opened, the carrier gas is supplied from the source G 7  to the raw material supply apparatus  40 , and when the valves V 9   a  and V 9   b  are closed, the supply of the carrier gas from the source G 7  to the raw material supply apparatus  40  is cut off. 
     The raw material supply apparatus  40  is connected to the processing apparatus  50  via pipes L 11  and L 12 , and supplies the reactive gas to the processing apparatus  50  via the pipes L 11  and L 12 . Valves V 11   a  to V 11   c  are provided in the pipe L 11 . When the valves V 11   a  to V 11   c  are opened, the reactive gas is supplied from the raw material supply apparatus  40  to the processing apparatus  50 , and when the valves V 11   a  to V 11   c  are closed, the supply of the reactive gas from the raw material supply apparatus  40  to the processing apparatus  50  is cut off. 
     One end of a pipe L 15  is connected between the valve V 11   a  and the valve V 11   b  of the pipe L 11 . The other end of the pipe L 15  is connected between the valve V 9   a  and the valve V 9   b  of the pipe L 9 . The pipe L 15  functions as a bypass pipe that connects the pipe L 9  and the pipe L 11  without interposing the raw material supply apparatus  40 . A valve V 15  is provided in the pipe L 15 . When the valve V 15  is opened, the pipe L 9  and the pipe L 11  communicate with each other, and when the valve V 15  is closed, the communication between the pipe L 9  and the pipe L 11  is cut off 
     One end of a pipe L 16  is connected between the valve V 11   b  and the valve V 11   c  of the pipe L 11 . The other end of the pipe L 16  is connected to an exhaust apparatus (not illustrated) such as a vacuum pump. A valve V 16  is provided in the pipe L 16 . When the valve V 16  is opened in a state in which the valves V 11   a  and V 11   b  are opened, the interior of the container  41  is exhausted so that the solvent can be removed from the solution M 1  stored in the container  41 . When the valve V 16  is closed, the removal of the solvent from the solution M 1  stored in the container  41  can be stopped. 
     The processing apparatus  50  is connected to the raw material supply apparatus  30  via the pipes L 10  and L 12 . The processing apparatus  50  is supplied with the reactive gas produced by heating and sublimating the second solid raw material M 2  in the raw material supply apparatus  30 . The processing apparatus  50  is connected to the raw material supply apparatus  40  via the pipes L 11  and L 12 . The processing apparatus  50  is supplied with the reactive gas produced by heating and sublimating the second solid raw material M 2  in the raw material supply apparatus  40 . 
     The processing apparatus  50  executes various processes such as a film forming process on a substrate such as a semiconductor wafer by using the reactive gases supplied from the raw material supply apparatuses  30  and  40 . In the present embodiment, the processing apparatus  50  includes a processing container  51 , a flow meter  52 , and a valve V 12 . The processing container  51  accommodates one or more substrates. In the present embodiment, the flow meter  52  is a mass flow meter (MFM). The flow meter  52  is provided in the pipe L 12  to measure a flow rate of the reactive gas flowing through the pipe L 12 . The valve V 12  is provided in the pipe L 12 . When the valve V 13  is opened, the reactive gas is supplied from the raw material supply apparatuses  30  and  40  to the processing container  51 , and when the valve V 13  is closed, the supply of the reactive gas from the raw material supply apparatuses  30  and  40  to the processing container  51  is cut off. 
     The control device  90  controls each part of the raw material supply system  1 . For example, the control device  90  controls the operations of the raw material source  10 , the buffer apparatus  20 , the raw material supply apparatuses  30  and  40 , the processing apparatus  50 , and the like. The control device  90  controls the opening/closing of various valves. The control device  90  may be, for example, a computer. 
     [Operation of Raw Material Supply System] 
     An example of the operation of the raw material supply system  1  (a raw material supply method) will be described with reference to  FIGS.  2  to  5   . In the raw material supply system  1 , the control device  90  controls the opening/closing operations of various valves to supply the reactive gas from one of the two raw material supply apparatuses  30  and  40 , which are provided in a parallel relationship with each other, to the processing apparatus  50 , and to fill the other raw material supply apparatus with a solid raw material. Hereinafter, an example of the operation of the raw material supply system  1  will be described in detail. 
     First, with reference to  FIGS.  2  and  3   , a case in which the raw material supply apparatus  30  supplies the reactive gas to the processing apparatus  50  and the raw material supply apparatus  40  is filled with the solid raw material will be described.  FIGS.  2  and  3    are views for explaining the operation of the raw material supply system  1 . In  FIGS.  2  and  3   , the pipes through which the carrier gas, the solution M 1 , and the reactive gas flow are indicated by the thick solid lines, and the pipes through which the carrier gas, the solution M 1 , and the reactive gas do not flow are indicated by thin solid lines. In addition, in  FIGS.  2  and  3   , states in which respective valves are open are indicated by the white symbols, and states in which respective valves are closed are indicated by the black symbols. The raw material supply system  1  will be described assuming that all the valves are closed in an initial state as illustrated in  FIG.  1   , and that the raw material supply apparatus  30  stores the second solid raw material M 2 . 
     The control device  90  controls the heating part  32  of the raw material supply apparatus  30  to heat and sublimate the second solid raw material M 2  in the container  31 , thereby producing the reactive gas. In addition, the control device  90  opens the valves V 8   a , V 8   b , V 10   a  to V 10   c , and V 12 . As a result, the carrier gas is injected from the source G 7  into the container  31  of the raw material supply apparatus  30  via the pipes L 7  and L 8 , and the reactive gas produced in the container  31  is supplied to the processing apparatus  50  via the pipes L 10  and L 12  together with the carrier gas. 
     The control device  90  opens the valves V 1 , V 2   a , and V 2   b , as illustrated in  FIG.  2   . As a result, the carrier gas is supplied from the source G 1  to the raw material source  10 , the solution M 1  is transported from the raw material source  10  to the buffer apparatus  20  via the pipe L 2 , and the solution M 1  is stored in the container  21  of the buffer apparatus  20 . At this time, since the valve V 4  is closed, the solution M 1  stored in the container  21  is not transported to the raw material supply apparatuses  30  and  40 . 
     Subsequently, the control device  90  determines whether or not a predetermined amount of solution M 1  is stored in the container  21  based on a detection value of the float sensor  22 . The predetermined amount is set to, for example, an amount capable of being stored in the container  41  of the raw material supply apparatus  40 . When it is determined that the predetermined amount of solution M 1  is stored in the container  21 , the control device  90  closes the valves V 1 , V 2   a , and V 2   b  and opens the valves V 3 , V 4 , and V 6 , as illustrated in  FIG.  3   . As a result, the carrier gas is supplied from the source G 3  to the buffer apparatus  20  via the pipe L 3 , and the solution M 1  is transported from the buffer apparatus  20  to the raw material supply apparatus  40  via the pipes L 4  and L 6 . As a result, the predetermined amount of solution M 1  is stored in the container  41  of the raw material supply apparatus  40 . In addition, the control device  90  opens the valves V 11   a , V 11   b , and V 16 , as illustrated in  FIG.  3   . As a result, the interior of the container  41  of the raw material supply apparatus  40  is exhausted by an exhaust apparatus, so that the solvent is removed from the solution M 1  in the container  41 , and the second solid raw material M 2  is formed in the container  41 . When removing the solvent from the solution M 1  in the container  41 , it is preferable for the control device  90  to control the heating part  42  to heat the solution M 1  in the container  41  to a predetermined temperature. This facilitates the removal of the solvent. The predetermined temperature is set to be lower than, for example, a temperature at which the second solid raw material M 2  is sublimated to produce the reactive gas.  FIG.  3    illustrate a state before the solvent is removed from the solution M 1  in the container  41 . 
     Next, with reference to  FIGS.  4  and  5   , a case in which the raw material supply apparatus  40  supplies the reactive gas to the processing apparatus  50  and the raw material supply apparatus  30  is filled with the solid raw material will be described.  FIGS.  4  and  5    are views for explaining the operation of the raw material supply system  1 . In  FIGS.  4  and  5   , the pipes through which the carrier gas, the solution M 1 , and the reactive gas flow are indicated by the thick solid lines, and the pipes through which the carrier gas, the solution M 1 , and the reactive gas do not flow are indicated by thin solid lines. In addition, in  FIGS.  4  and  5   , states in which respective valves are open are indicated by the white symbols, and states in which respective valves are closed are indicated by the black symbols. In the raw material supply system  1 , it is assumed that all the valves are closed in an initial state, as illustrated in  FIG.  1   . In addition, the second solid raw material M 2  will be described as being stored in the raw material supply apparatus  40 , as illustrated in  FIG.  4   . 
     The control device  90  controls the heating part  42  of the raw material supply apparatus  40  to heat and sublimate the second solid raw material M 2  in the container  41 , thereby producing the reactive gas. In addition, the control device  90  opens the valves V 9   a , V 9   b , V 11   a  to V 11   c , and V 12 . As a result, the carrier gas is injected from the source G 7  into the container  41  of the raw material supply apparatus  40  via the pipes L 7  and L 9 , and the reactive gas produced in the container  41  is supplied to the processing apparatus  50  via the pipes L 11  and L 12  together with the carrier gas. 
     The control device  90  opens the valves V 1 , V 2   a , and V 2   b , as illustrated in  FIG.  4   . As a result, the carrier gas is supplied from the source G 1  to the raw material source  10 , the solution M 1  is transported from the raw material source  10  to the buffer apparatus  20  via the pipe L 2 , and the solution M 1  is stored in the container  21  of the buffer apparatus  20 . At this time, since the valve V 4  remains closed, the solution M 1  stored in the container  21  is not transported to the raw material supply apparatuses  30  and  40 . 
     Subsequently, the control device  90  determines whether or not a predetermined amount of solution M 1  is stored in the container  21  based on a detection value of the float sensor  22 . The predetermined amount is set to, for example, an amount capable of being stored in the container  31  of the raw material supply apparatus  30 . When it is determined that the predetermined amount of solution M 1  is stored in the container  21 , the control device  90  closes the valves V 1 , V 2   a , and V 2   b  and opens the valves V 3 , V 4 , and V 5 , as illustrated in  FIG.  5   . As a result, the carrier gas is supplied from the source G 3  to the buffer apparatus  20  via the pipe L 3 , and the solution M 1  is transported from the buffer apparatus  20  to the raw material supply apparatus  30  via the pipes L 4  and L 5 . As a result, the predetermined amount of solution M 1  is stored in the container  31  of the raw material supply apparatus  30 . In addition, the control device  90  opens the valves V 10   a , V 10   b , and V 14 , as illustrated in  FIG.  5   . As a result, the interior of the container  31  of the raw material supply apparatus  30  is exhausted by the exhaust apparatus, so that the solvent is removed from the solution M 1  in the container  31 , and the second solid raw material M 2  is formed in the container  31 . When removing the solvent from the solution M 1  in the container  31 , it is preferable for the control device  90  to control the heating part  32  to heat the solution M 1  in the container  31  to a predetermined temperature. This facilitates the removal of the solvent. The predetermined temperature is set to be lower than, for example, a temperature at which the second solid raw material is sublimated to produce the reactive gas.  FIG.  5    illustrate a state before the solvent is removed from the solution M 1  in the container  41 . 
     As described above, according to the raw material supply system  1 , the control device  90  controls the opening/closing operations of respective valves so that the reactive gas is supplied from one of the two raw material supply apparatuses  30  and  40  to the processing apparatus  50 , and the other raw material supply apparatus is filled with the solid raw material. This makes it possible for the raw material to be automatically replenished to the raw material supply apparatuses  30  and  40 , to improve the continuous operation performance of the processing apparatus  50 , and to improve the operating rate of the processing apparatus  50 . 
     In addition, according to the raw material supply system  1 , the buffer apparatus  20  including the float sensor  22  is provided between the raw material source  10  and the raw material supply apparatuses  30  and  40 . This makes it possible to control a liquid amount of the solution M 1  to be transported from the raw material source  10  inside the buffer apparatus  20 , and to transport the controlled amount of solution M 1  to the raw material supply apparatuses  30  and  40 . Therefore, it is possible to control the liquid amount of the solution M 1  stored in the raw material supply apparatuses  30  and  40  even without providing the float sensor in the raw material supply apparatuses  30  and  40 . As a result, it is possible to heat sublimate the solution M 1  in the raw material supply apparatuses  30  and  40  without being restricted in uses by the level sensor, such as a heat-resistant temperature, a heat cycle durability, and an operational reliability of the float sensor. That is, it is possible to expand a range of the temperature at which the solution M 1  can be heated in the raw material supply apparatuses  30  and  40 . 
     Second Embodiment 
     A raw material supply system of a second embodiment will be described with reference to  FIG.  6   .  FIG.  6    is a view illustrating the raw material supply system according to the second embodiment. 
     The raw material supply system  1 A is different from the raw material supply system  1  of the first embodiment in that raw material supply apparatuses  30 A and  40 A include raw material injection parts  34  and  44  that spray a solution M 1  transported from the buffer apparatus  20  and inject the solution M 1  into containers  31  and  41 , respectively. Since the other configurations are the same as those of the raw material supply system  1  of the first embodiment, different configurations will be mainly described below. 
     The raw material supply apparatus  30 A stores the solution M 1  transported from the buffer apparatus  20 . In the present embodiment, the raw material supply apparatus  30 A includes a container  31 , a heating part  32 , a pressure gauge  33 , and a raw material injection part  34 . The container  31  stores the solution M 1  transported from the buffer apparatus  20 . The heating part  32  heats the second solid raw material M 2  formed by removing the solvent from the solution M 1 , thereby sublimating the second solid raw material M 2  to produce the reactive gas. The heating part  32  may be, for example, a heater disposed so as to cover the bottom portion and the outer periphery of the container  31 . The heating part  32  is configured to be able to heat the interior of the container  31  to a temperature capable of sublimating the second solid raw material M 2  to produce the reactive gas. The pressure gauge  33  detects the internal pressure of the container  31 . The detected internal pressure of the container  31  is transmitted to the control device  90 . The control device  90  controls the opening/closing operations of various valves based on the detected internal pressure. For example, when the detected internal pressure becomes higher than a predetermined pressure, the control device  90  closes the valve V 5  to prevent the excess solution M 1  from being supplied to the container  31 . 
     The raw material injection part  34  sprays the solution M 1  transported from the buffer apparatus  20  via the pipes L 4  and L 5  and injects the solution M 1  into the container  31 . By spraying the solution M 1  by the raw material injection part  34 , the solvent is vaporized before the solution M 1  reaches the bottom portion of the container  31  or the like, and deposited as the second solid raw material M 2 . The raw material injection part  34  may be, for example, a spray nozzle. 
     The raw material supply apparatus  40 A stores the solution M 1  transported from the buffer apparatus  20 . In the present embodiment, the raw material supply apparatus  40 A includes a container  41 , a heating part  42 , a pressure gauge  43 , and a raw material injection part  44 . 
     The container  41 , the heating part  42 , the pressure gauge  43 , and the raw material injection part  44  may have the same configurations as the container  31 , the heating part  32 , the pressure gauge  33 , and the raw material injection part  34  in the raw material supply apparatus  30 A. 
     As described above, according to the raw material supply system  1 A, as in the raw material supply system  1 , the control device  90  controls the opening/closing operations of the valves, so that one of the two raw material supply apparatuses  30 A and  40 A supplies the reactive gas to the processing apparatus  50  and the other is filled with the solid raw material. This makes it possible for the raw material to be automatically replenished to the raw material supply apparatuses  30 A and  40 A, to improve the continuous operation performance of the processing apparatus  50 , and to improve the operating rate of the processing apparatus  50 . 
     According to the raw material supply system  1 A, by spraying and injecting the solution M 1  into the containers  31  and  41  from the raw material injection parts  34  and  44 , respectively, the solvent is vaporized before the solution M 1  reaches the bottom portions of the containers  31  and  41  and the like, and deposited as the second solid raw material M 2 . As described above, in the raw material supply system  1 A, since the solution M 1  injected into the containers  31  and  41  is deposited and stored as the solid material on the bottom portions of the containers  31  and  41 , it is possible to increase an amount of storable solid raw material per fixed volume. 
     In the raw material supply system  1 A, the solution M 1  obtained by dissolving the solid raw material in the solvent is sprayed and vaporized, and deposited once on the bottom portions of the containers  31  and  41  as the second solid raw material M 2 . Thereafter, the second solid raw material M 2  is sublimated and supplied to the processing apparatus  50 . This facilitates control such as simplification of flow rate control or increase in flow rate. 
     According to the raw material supply system  1 A, as in the raw material supply system  1 , the buffer apparatus  20  including the float sensor  22  is provided between the raw material source  10  and the raw material supply apparatuses  30 A and  40 A. This makes it possible to control a liquid amount of solution M 1  transported from the raw material source  10  in the buffer apparatus  20 , to transport the solution M 1  of the controlled liquid amount to the raw material supply apparatuses  30 A and  40 A, and to spray the solution M 1  into the containers  31  and  41  from the raw material injection parts  34  and  44 . Therefore, it is possible to control a storage amount of the second solid raw material M 2  deposited as the solvent is vaporized by the spraying of the solution M 1  into the containers  31  and  41 . 
     Third Embodiment 
     A raw material supply system of a third embodiment will be described with reference to  FIG.  7   .  FIG.  7    is a view illustrating the raw material supply system according to the third embodiment. 
     A raw material supply system  1 B is different from the raw material supply system  1  of the first embodiment in that each of the interiors of the containers  31  and  41  is formed in multiple stages. Since the other configurations are the same as those of the raw material supply system  1  of the first embodiment, different configurations will be mainly described below. 
     The raw material supply apparatus  30 B stores the solution M 1  transported from the buffer apparatus  20 . In the present embodiment, the raw material supply apparatus  30 B includes a container  31 , a heating part  32 , a pressure gauge  33 , partition plates  35  and  36 , and through pipes  37  and  38 . 
     The container  31 , the heating part  32 , and the pressure gauge  33  may be the same as those of the raw material supply apparatus  30  of the first embodiment. 
     The partition plate  35  is provided inside the container  31  and divides the interior of the container  31  into two upper and lower regions. The partition plate  35  is made of a material that is impermeable to a solution, a solid raw material and a reactive gas, such as stainless steel or a nickel alloy. 
     The partition plate  36  is provided below the partition plate  35  inside the container  31 , and divides a region below the partition plate  35  inside the container  31  into two upper and lower regions. The partition plate  36  is made of, for example, the same material as that of the partition plate  35 . 
     The through pipe  37  is provided to penetrate the partition plate  35  in a thickness direction (vertical direction), and the solution and the reactive gas pass through the partition plate  35  through the through pipe  37 . A height extending upward from the top surface of the partition plate  35  of the through pipe  37  is high enough to secure a required amount of raw material. One or more (two in the illustrated example) through pipes  37  are provided in the plane of the partition plate  35 . 
     The through pipe  38  is provided to penetrate the partition plate  36  in the thickness direction (vertical direction), and the solution and the reactive gas pass through the partition plate  36  through the through pipe  38 . A height extending upward from the top surface of the partition plate  36  of the through pipe  38  is high enough to secure a required amount of raw material. One or more (one in the illustrated example) through pipes  38  are provided in the plane of the partition plate  36 . 
     As described above, since the partition plates  35  and  36  are provided inside the container  31 , the solution transported from the buffer apparatus  20  into the container  31  is stored on the partition plate  35 , on the partition plate  36 , and on the bottom of the container  31 . Therefore, since a specific surface area, which is a surface area per unit volume of the solution stored in the container  31 , becomes large, it is possible to shorten a time for removing the solvent from the solution. In addition, it is possible to increase an amount of the reactive gas produced by sublimating the solid raw material formed by removing the solvent from the solution. 
     The raw material supply apparatus  40 B stores the solution M 1  transported from the buffer apparatus  20 . In the present embodiment, the raw material supply apparatus  40 B includes a container  41 , a heating part  42 , a pressure gauge  43 , partition plates  45  and  46 , and through pipes  47  and  48 . 
     The container  41 , the heating part  42 , the pressure gauge  43 , the partition plates  45  and  46  and the through pipes  47  and  48  have the same configurations as the container  31 , the heating part  32 , the pressure gauge  33 , the partition plates  35  and  36  and the through pipes  37  and  38  in the raw material supply apparatus  30 B. 
     As described above, since the partition plates  45  and  46  are provided inside the container  41 , the solution transported from the buffer apparatus  20  into the container  41  is stored on the partition plate  45 , on the partition plate  46 , and on the bottom of the container  41 . Therefore, since a specific surface area, which is a surface area per unit volume of the solution stored in the container  41 , becomes large, it is possible to shorten a time for removing the solvent from the solution. In addition, it is possible to increase an amount of the reactive gas produced by sublimating the solid raw material formed by removing the solvent from the solution. 
     As described above, according to the raw material supply system  1 B, as in the raw material supply system  1 , the control device  90  controls the opening/closing operations of the valves, so that one of the two raw material supply apparatuses  30 B and  40 B supplies the reactive gas to the processing apparatus  50  and the other is filled with the solid raw material. This makes it possible for the raw material to be automatically replenished to the raw material supply apparatuses  30 B and  40 B, to improve the continuous operation performance of the processing apparatus  50 , and to improve the operating rate of the processing apparatus  50 . 
     According to the raw material supply system  1 B, as in the raw material supply system  1 , the buffer apparatus  20  including the float sensor  22  is provided between the raw material source  10  and the raw material supply apparatuses  30 B and  40 B. This makes it possible to control a liquid amount of the solution M 1  to be transported from the raw material source  10  in the buffer apparatus  20 , and to transport the controlled amount of the solution M 1  to the raw material supply apparatuses  30 B and  40 B. Therefore, it is possible to control the liquid amount of the solution M 1  stored in the raw material supply apparatuses  30 B and  40 B even without providing the float sensor in the raw material supply apparatuses  30 B and  40 B. As a result, it is possible to heat and sublimate the solution M 1  in the raw material supply apparatuses  30 B and  40 B without being restricted in uses by the level sensor such as a heat-resistant temperature, a heat cycle durability, and an operational reliability of the float sensor. That is, it is possible to expand a range of a temperature at which the solution M 1  can be heated in the raw material supply apparatuses  30 B and  40 B. 
     According to the raw material supply system  1 B, each of the interiors of the containers  31  and  41  is formed in multiple stages. As a result, the solution transported from the buffer apparatus  20  into the containers  31  and  41  is stored on the partition plates  35  and  45 , on the partition plates  36  and  46 , and on the bottom of the containers  31  and  41 . Therefore, since a specific surface area, which is a surface area per unit volume of the solution stored in the containers  31  and  41 , becomes large, it is possible to shorten a time for removing the solvent from the solution. In addition, it is possible to increase an amount of the reactive gas produced by sublimating the solid raw material formed by removing the solvent from the solution. 
     In the third embodiment, the case in which each of the interiors of the containers  31  and  41  of the raw material supply system  1  of the first embodiment is formed in multiple stages has been described, but the present disclosure is not limited thereto. For example, each of the interiors of the containers  31  and  41  of the raw material supply system  1 A of the second embodiment may be formed in multiple stages. 
     In the above-described embodiments, the buffer apparatus  20  is an example of a first storage part, the raw material supply apparatuses  30 ,  30 A,  30 B,  40 ,  40 A, and  40 B are examples of second storage parts, and the float sensor  22  is an example of a detection part. In addition, the pipes L 10  and L 11  are examples of exhaust ports, and the raw material injection parts  34  and  44  are examples of injection parts. The control device  90  is an example of a controller. 
     The embodiments disclosed herein should be considered to be exemplary in all respects and not restrictive. The above-described embodiments may be omitted, replaced, or modified in various forms without departing from the scope and spirit of the appended claims. 
     In the above-described embodiments, the system in which the second solid raw material M 2  formed by removing the solvent from the solution M 1  is sublimated to produce the reactive gas, and the produced reactive gas is used to form a film in the processing apparatus  50  has been described, the present disclosure is not limited thereto. For example, instead of the solution M 1 , a dispersion such as a slurry obtained by dispersing the first solid raw material in a solvent or a sol obtained by dispersing the first solid raw material in a solvent may be used. For example, by using the sol, it is possible to fill a precursor having a higher concentration than using the solution M 1  or the slurry. The slurry is also referred to as a suspension. The sol is also referred to as a colloidal solution. 
     The present international application claims priority based on Japanese Patent Application No. 2020-046446 filed on Mar. 17, 2020 and Japanese Patent Application No. 2020-118056 filed on Jul. 8, 2020, the disclosures of which are incorporated herein by reference in their entireties. 
     EXPLANATION OF REFERENCE NUMERALS 
     
         
         
           
               1 ,  1 A,  1 B: raw material supply system,  20 : buffer apparatus,  22 : float sensor,  30 ,  30 A,  30 B,  40 ,  40 A,  40 B: raw material supply apparatus,  32 ,  42 : heating part