Patent Publication Number: US-2021180185-A1

Title: Substrate processing apparatus, method of manufacturing semiconductor device, and recording medium

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a Bypass Continuation Application of PCT International Application No. PCT/JP2018/033627, filed Sep. 11, 2018, the disclosure of which is incorporated herein in its entirety by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a substrate processing apparatus, a method of manufacturing a semiconductor device, and a recording medium. 
     BACKGROUND 
     In the related art, as a process of manufacturing a semiconductor device, a process gas may be supplied to a substrate accommodated in a reaction tube to perform a process (for example, a film-forming process) on the substrate. At this time, when reaction by-products adhere to an inner wall of the reaction tube, foreign substances (particles) are generated due to the reaction by-products, which deteriorates a quality of the process on the substrate. 
     SUMMARY 
     Some embodiments of the present disclosure provide a technique capable of preventing generation of deposits on an inner wall of a reaction tube. 
     According to some embodiments of the present disclosure, there is provided a technique that includes: a substrate support configured to support at least one substrate; a reaction tube configured to accommodate the at least one substrate support and process the at least one substrate; and an inert gas supply system configured to supply an inert gas into the reaction tube, wherein the inert gas supply system includes a nozzle including at least one first ejection hole configured to eject the inert gas toward a center of the at least one substrate and at least one second ejection hole configured to eject the inert gas toward an inner wall of the reaction tube. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure. 
         FIG. 1  is a schematic configuration view of a vertical process furnace of a substrate processing apparatus suitably used in some embodiments of the present disclosure, in which a portion of the process furnace is illustrated in a vertical cross-sectional view. 
         FIG. 2  is a schematic configuration view of the vertical process furnace of the substrate processing apparatus suitably used in some embodiments of the present disclosure, in which a portion of the process furnace is illustrated in a cross-sectional view taken along a line A-A in  FIG. 1 . 
         FIG. 3  is a schematic configuration view of a nozzle structure of a substrate processing apparatus suitably used in some embodiments of the present disclosure, in which a portion of the nozzle structure is illustrated in a vertical cross-sectional view. 
         FIGS. 4A and 4B  are schematic configuration views of a buffer structure of a substrate processing apparatus suitably used in some embodiments of the present disclosure, in which  FIG. 4A  is an enlarged horizontal cross-sectional view for explaining the buffer structure, and  FIG. 4B  is a schematic view for explaining the buffer structure. 
         FIG. 5  is a schematic configuration diagram of a controller of the substrate processing apparatus suitably used in some embodiments of the present disclosure, in which a control system of the controller is illustrated in a block diagram. 
         FIG. 6  is a flowchart of a substrate processing process according to some embodiments of the present disclosure. 
         FIG. 7  is a diagram showing gas supply timings in the substrate processing process according to some embodiments of the present disclosure. 
         FIGS. 8A and 8B  are schematic configuration views for explaining a first modification of a nozzle structure of a substrate processing apparatus suitably used in some embodiments of the present disclosure, in which  FIG. 8A  is an enlarged horizontal cross-sectional view of a portion of the nozzle structure, and  FIG. 8B  is an enlarged horizontal cross-sectional view of a portion of a gas supply hole in a nozzle. 
         FIG. 9  is a schematic configuration view for explaining a second modification of a nozzle structure of a substrate processing apparatus suitably used in some embodiments of the present disclosure, in which a portion of the nozzle structure is illustrated in a vertical cross-sectional view. 
         FIG. 10  is a schematic configuration view for explaining a third modification of a nozzle structure of a substrate processing apparatus suitably used in some embodiments of the present disclosure, in which a portion of the nozzle structure is illustrated in a horizontal cross-sectional view. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure will be now described with reference to  FIGS. 1 to 7 . 
     (1) Configuration of Substrate Processing Apparatus (Heating Device) 
     As illustrated in  FIG. 1 , a process furnace  202  is a so-called vertical furnace in which substrates can be accommodated in multiple stages in a vertical direction, and includes a heater  207  as a heating device (a heating mechanism). The heater  207  has a cylindrical shape and is supported by a heater base (not shown) serving as a holding plate to be vertically installed. As will be described later, the heater  207  also functions as an activation mechanism (an excitation part) configured to thermally activate (excite) a gas. 
     (Process Chamber) 
     A reaction tube  203  is disposed inside the heater  207  to be concentric with the heater  207 . The reaction tube  203  is made of, for example, a heat resistant material such as quartz (SiO 2 ), silicon carbide (SiC) or silicon nitride (SiN) and is formed in a cylindrical shape with its upper end closed and its lower end opened. A manifold (inlet flange)  209  is disposed under the reaction tube  203  to be concentric with the reaction tube  203 . The manifold  209  is made of, for example, metal such as stainless steel (SUS: Steel Use Stainless) and is formed in a cylindrical shape with both of its upper and lower ends opened. The upper end portion of the manifold  209  engages with the lower end portion of the reaction tube  203  to support the reaction tube  203 . An O-ring  220   a  serving as a seal member is installed between the manifold  209  and the reaction tube  203 . As the manifold  209  is supported by the heater base, the reaction tube  203  is in a state of being vertically installed. A process container (reaction container) mainly includes the reaction tube  203  and the manifold  209 . A process chamber  201  is formed in a hollow cylindrical portion which is the inside of the process container. The process chamber  201  is configured to be capable of accommodating a plurality of wafers  200  as substrates. Note that the process container is not limited to the above configuration, and only the reaction tube  203  may be referred to as the process container. 
     Nozzles  249   a  and  249   b  are installed in the process chamber  201  to penetrate a sidewall of the manifold  209 . Gas supply pipes  232   a  and  232   b  are connected to the nozzles  249   a  and  249   b , respectively. In this way, the two nozzles  249   a  and  249   b  and the two gas supply pipes  232   a  and  232   b  are installed at the reaction tube  203 , thereby allowing plural types of gases to be supplied into the process chamber  201 . 
     Mass flow controllers (MFCs)  241   a  and  241   b , which are flow rate controllers (flow rate control parts), and valves  243   a  and  243   b , which are opening/closing valves, are installed at the gas supply pipes  232   a  and  232   b , respectively, sequentially from the corresponding upstream sides of a gas flow. Gas supply pipes  232   c  and  232   d  configured to supply an inert gas are connected to the gas supply pipes  232   a  and  232   b  at downstream sides of the valves  243   a  and  243   b , respectively. MFCs  241   c  and  241   d  and valves  243   c  and  243   d  are installed at the gas supply pipes  232   c  and  232   d , respectively, sequentially from the corresponding upstream sides of a gas flow. 
     As illustrated in  FIG. 2 , the nozzle  249   a  is installed in a space between an inner wall of the reaction tube  203  and the wafers  200  to extend upward along a stack direction of the wafers  200  from a lower portion to an upper portion of the inner wall of the reaction tube  203 . Specifically, the nozzle  249   a  is installed in a region horizontally surrounding a wafer arrangement region (mounting region) in which the wafers  200  are arranged (mounted) at a lateral side of the wafer arrangement region, along the wafer arrangement region. That is, the nozzle  249   a  is installed in a perpendicular relationship with the surfaces (flat surfaces) of the wafers  200  at a lateral side of end portions (peripheral portions) of the respective wafers  200  loaded into the process chamber  201 . 
     As illustrated in  FIGS. 2 and 3 , as gas supply holes configured to supply a gas, a first ejection hole  250   a  and a second ejection hole  250   b  are formed on the side surface of the nozzle  249   a.    
     The first ejection hole  250   a  is opened toward a center of the reaction tube  203  (the wafers  200 ) to allow a gas (particularly an inert gas) to be supplied (ejected) to the wafers  200 . That is, the first ejection hole  250   a  is formed on one side surface of the nozzle  249   a  to eject the inert gas or the like toward the centers of the wafers  200 . 
     The second ejection hole  250   b  is opened toward the inner wall of the reaction tube  203  to allow a gas (particularly an inert gas) to be supplied (ejected) to the inner wall of the reaction tube  203 . That is, the second ejection hole  250   b  is formed on the other side surface of the nozzle  249   a  (a surface facing the first ejection hole  250   a ) to eject the inert gas or the like to the inner wall of the reaction tube  203 . 
     In this way, the first ejection hole  250   a  configured to eject the inert gas or the like toward the center of the wafers  200  and the second ejection hole  250   b  configured to eject the inert gas or the like toward the inner wall of the reaction tube  203  are formed at positions opposite to each other in the nozzle  249   a.    
     A plurality of first ejection holes  250   a  and a plurality of second ejection holes  250   b  are formed from the lower portion to the upper portion of the reaction tube  203 . Specifically, the plurality of first ejection holes  250   a  are formed from the lower portion to the upper portion of the reaction tube  203  along a height direction of the nozzle  249   a . The first ejection holes  250   a  are formed to have the same opening area at first predetermined intervals. Further, the plurality of second ejection holes  250   b  are formed from the lower portion to the upper portion of the reaction tube  203  along the height direction of the nozzle  249   a . The second ejection holes  250   b  are formed to have the same opening area at second predetermined intervals, each of which is wider than each of the first predetermined intervals. That is, the plurality of first ejection holes  250   a  are formed at the first predetermined intervals with respect to the height direction of the nozzle  249   a , and the plurality of second ejection holes  250   b  are formed at the second predetermined intervals, each of which is wider than each of the first predetermined intervals, with respect to the height direction of the nozzle  249   a.    
     Since the second predetermined interval is wider than the first predetermined interval, the number of first ejection holes  250   a  is larger than the number of the second ejection holes  250   b . Specifically, the first ejection holes  250   a  and the second ejection holes  250   b  are formed at, for example, a ratio of 2.5:1 in number. Further, it is assumed that an opening diameter of the first ejection holes  250   a  is larger than an opening diameter of the second ejection holes  250   b . Specifically, the opening diameter of the first ejection holes  250   a  and the opening diameter of the second ejection holes  250   b  are formed, for example, at a ratio of 2:1. Further, each of the ratios given here is merely a specific example, but the present disclosure is not limited thereto. Further, shapes of openings of the first ejection holes  250   a  and shapes of openings of the second ejection holes  250   b  may be circular but are not limited thereto. For example, these holes  250   a  and  250   b  may have another shape such as an elliptical shape. 
     As illustrated in  FIGS. 1 and 2 , the nozzle  249   b  is connected to a leading end of the gas supply pipe  232   b . The nozzle  249   b  is disposed in a buffer chamber  237  serving as a gas dispersion space. As illustrated in  FIG. 2 , the buffer chamber  237  is disposed in an annular space, in a plane view), between the inner wall of the reaction tube  203  and the wafers  200 , along the stack direction of the wafers  200  from the lower portion to the upper portion of the inner wall of the reaction tube  203 . That is, the buffer chamber  237  is formed by a buffer structure  300  along the wafer arrangement region in a region horizontally surrounding the wafer arrangement region at the lateral side of the wafer arrangement region. The buffer structure  300  is made of insulating material such as quartz. Gas supply ports  302  and  304  configured to supply a gas are formed on an arc-shaped wall surface of the buffer structure  300 . As illustrated in  FIGS. 2, 4A and 4B , the gas supply ports  302  and  304  are respectively opened toward the center of the reaction tube  203  at positions opposite to plasma generation regions  224   a  and  224   b  between rod-shaped electrodes  269  and  270  to be described below and between rod-shaped electrodes  270  and  271  to be described below, thereby allowing a gas to be supplied toward the wafers  200 . A plurality of gas supply ports  302  and  304  may be formed to have the same opening area at the same opening pitch between the lower portion and the upper portion of the reaction tube  203 . 
     The nozzle  249   b  is installed to extend upward along the stack direction of the wafers  200  from the lower portion to the upper portion of the inner wall of the reaction tube  203 . Specifically, the nozzle  249   b  is installed in a region horizontally surrounding the wafer arrangement region in which the wafers  200  are arranged at the lateral side of the wafer arrangement region inside the buffer structure  300 , along the wafer arrangement region. That is, the nozzle  249   b  is installed in a perpendicular relationship with the surfaces of the wafers  200  at the lateral side of the end portions of the wafers  200  loaded into the process chamber  201 . A gas supply hole  250   c  configured to supply a gas is formed on the side surface of the nozzle  249   b . The gas supply hole  250   c  is opened toward a wall surface formed in the radial direction with respect to the arc-shaped wall surface of the buffer structure  300 , thereby allowing a gas to be supplied toward the wall surface. As a result, a reaction gas is dispersed in the buffer chamber  237  and is not directly ejected to the rod-shaped electrodes  269  to  271 , thereby suppressing generation of particles. As with the first ejection holes  250   a , a plurality of gas supply holes  250   c  are formed between the lower portion and the upper portion of the reaction tube  203 . 
     In this way, in the embodiments, a gas is transferred via the nozzles  249   a  and  249   b  and the buffer chamber  237  arranged in an annular longitudinal space, that is, a cylindrical space, in the plane view, defined by the inner wall of the side wall of the reaction tube  203  and the ends of the plurality of wafers  200  arranged in the reaction tube  203 . Then, the gas is ejected into the reaction tube  203  near the wafers  200  for the first time from the first ejection holes  250   a , the second ejection holes  250   b , and gas supply holes  250   c  formed in the nozzles  249   a  and  249   b  and the gas supply ports  302  and  304  formed in the buffer chamber  237 . The main flow of the gas in the reaction tube  203  is in a direction parallel to the surfaces of the wafers  200 , that is, in a horizontal direction. With such a configuration, the gas can be uniformly supplied to each wafer  200 , so that uniformity of film thickness formed on each wafer  200  can be improved. A gas flowing on the surfaces of the wafers  200 , that is, the residual gas after reaction flows toward an exhaust port, that is, an exhaust pipe  231  to be described below. However, a direction of the flow of the residual gas is appropriately specified depending on the position of the exhaust port, and is not limited to the vertical direction. 
     A precursor containing a predetermined element, for example, a silane precursor gas containing silicon (Si) as the predetermined element, is supplied from the gas supply pipe  232   a  into the process chamber  201  via the MFC  241   a , the valve  243   a , and the nozzle  249   a.    
     A precursor gas refers to a gaseous precursor, for example, a gas obtained by vaporizing a precursor in a liquefied state at normal temperature and normal pressure, a precursor in a gaseous state at normal temperature and normal pressure, and the like. When the term “precursor” is used herein, it may indicate a case of including a “liquid precursor in a liquefied state,” a case of including a “precursor gas in a gaseous state,” or a case of including both of them. 
     An example of the silane precursor gas may include a precursor gas containing Si and a halogen element, that is, a halosilane precursor gas. The halosilane precursor is a silane precursor having a halogen group. The halogen element includes at least one selected from the group of chlorine (Cl), fluorine (F), bromine (Br), and iodine (I). That is, the halosilane precursor contains at least one halogen group selected from the group of a chloro group, a fluoro group, a bromo group, and an iodo group. The halosilane precursor may be said to be a type of halide. 
     An example of the halosilane precursor gas may include a precursor gas containing Si and Cl, that is, a chlorosilane precursor gas. An example of the chlorosilane precursor gas may include a dichlorosilane (SiH 2 Cl 2 , abbreviation: DCS) gas. 
     A reactant containing an element different from the above-mentioned predetermined element, for example, a nitrogen (N)-containing gas as a reaction gas, is supplied from the gas supply pipe  232   b  into the process chamber  201  via the MFC  241   b , the valve  243   b , and the nozzle  249   b . An example of the N-containing gas may include a hydrogen nitride-based gas. The hydrogen nitride-based gas may be said to be a substance including only two elements of N and H, and acts as a nitriding gas, that is, a N source. An example of the hydrogen nitride-based gas may include an ammonia (NH 3 ) gas. 
     An inert gas, for example, a nitrogen (N 2 ) gas, is supplied from the gas supply pipes  232   c  and  232   d  into the process chamber  201  via the MFCs  241   c  and  241   d , the valves  243   c  and  243   d , the gas supply pipes  232   a  and  232   b , and the nozzles  249   a  and  249   b , respectively. 
     A precursor supply system as a first gas supply system mainly includes the gas supply pipe  232   a , the MFC  241   a , and the valve  243   a . Further, a reactant supply system as a second gas supply system mainly includes the gas supply pipe  232   b , the MFC  241   b , and the valve  243   b . The precursor supply system and the reactant supply system are collectively referred to as a process gas supply system (a process gas supply part). The precursor gas and the reaction gas are collectively referred to as a process gas. 
     An inert gas supply system mainly includes the gas supply pipes  232   c  and  232   d , the MFCs  241   c  and  241   d , and the valves  243   c  and  243   d . The inert gas supply system may include the nozzle  249   a  connected to the gas supply pipe  232   c  via the gas supply pipe  232   a . In that case, the inert gas supply system includes the nozzle  249   a  with the first ejection holes  250   a  and the second ejection holes  250   b.    
     The precursor supply system, the reactant supply system, and the inert gas supply system described above are also collectively referred to as a gas supply system (a gas supply part). 
     (Plasma Generation Part) 
     As illustrated in  FIGS. 2, 4A, and 4B , three rod-shaped electrodes  269 ,  270 , and  271 , which are made of a conductor and have an elongated structure, are disposed in the buffer chamber  237  to span from the lower portion to the upper portion of the reaction tube  203  along the stack direction of the wafers  200 . Each of the rod-shaped electrodes  269 ,  270 , and  271  is installed parallel to the nozzle  249   b . Each of the rod-shaped electrodes  269 ,  270 , and  271  is covered with and protected by an electrode protective tube  275  over a region spanning from an upper portion to a lower portion thereof. Of the rod-shaped electrodes  269 ,  270 , and  271 , the rod-shaped electrodes  269  and  271  disposed at both ends are connected to a high frequency power supply  273  via a matching device  272 . The rod-shaped electrode  270  is grounded by being connected to the ground that is the reference potential. That is, the rod-shaped electrodes connected to the high frequency power supply  273  and the grounded rod-shaped electrode are alternately arranged. As the grounded rod-shaped electrode, the rod-shaped electrode  270  interposed between the rod-shaped electrodes  269  and  271  connected to the high frequency power supply  273  is used in common for the rod-shaped electrodes  269  and  271 . In other words, the grounded rod-shaped electrode  270  is disposed to be sandwiched between the rod-shaped electrodes  269  and  271  connected to the adjacent high frequency power supply  273 , and the rod-shaped electrode  269  and the rod-shaped electrode  270 , and similarly, the rod-shaped electrode  271  and the rod-shaped electrode  270  are configured to be paired to generate plasma. That is, the grounded rod-shaped electrode  270  is used in common for the rod-shaped electrodes  269  and  271  connected to two high frequency power supplies  273  adjacent to the rod-shaped electrode  270 . Then, by applying high frequency (RF) power from the high frequency power supply  273  to the rod-shaped electrodes  269  and  271 , plasma is generated in a plasma generation region  224   a  between the rod-shaped electrodes  269  and  270  and in a plasma generation region  224   b  between the rod-shaped electrodes  270  and  271 . A plasma generation part (a plasma generator) as a plasma source mainly includes the rod-shaped electrodes  269 ,  270 , and  271  and the electrode protective tube  275 . The plasma source may include the matching device  272  and the high frequency power supply  273 . As described below, the plasma source functions as a plasma excitation part (an activation mechanism) that plasma-excites a gas, that is, excites (activates) a gas into a plasma state. 
     The electrode protective tube  275  has a structure in which each of the rod-shaped electrodes  269 ,  270 , and  271  can be inserted into the buffer chamber  237  while keeping each of the rod-shaped electrodes  269 ,  270 , and  271  isolated from an internal atmosphere of the buffer chamber  237 . In a case where an O 2  concentration within the electrode protective tube  275  is substantially equal to an O 2  concentration in an ambient air (atmosphere), each of the rod-shaped electrodes  269 ,  270 , and  271  inserted into the electrode protective tube  275  may be oxidized by heat generated from the heater  207 . For this reason, by charging the interior of the electrode protective tube  275  with an inert gas such as a N 2  gas, or by purging the interior of the electrode protective tube  275  with an inert gas such as a N 2  gas through the use of an inert gas purge mechanism, it is possible to reduce the O 2  concentration within the electrode protective tube  275 , thereby preventing oxidation of the rod-shaped electrodes  269 ,  270 , and  271 . 
     (Exhaust Part) 
     As illustrated in  FIGS. 1 and 2 , the exhaust pipe  231  configured to exhaust an internal atmosphere of the process chamber  201  is installed at the reaction tube  203 . A vacuum pump  246 , as a vacuum-exhausting device, is connected to the exhaust pipe  231  via a pressure sensor  245 , which is a pressure detector (pressure detecting part) that detects an internal pressure of the process chamber  201 , and an auto pressure controller (APC) valve  244 , which is an exhaust valve (pressure regulation part). The APC valve  244  is configured to perform or stop a vacuum-exhausting operation in the process chamber  201  by opening or closing the valve while the vacuum pump  246  is actuated, and is also configured to regulate the internal pressure of the process chamber  201  by adjusting an opening degree of the valve based on pressure information detected by the pressure sensor  245  while the vacuum pump  246  is actuated. An exhaust system mainly includes the exhaust pipe  231 , the APC valve  244 , and the pressure sensor  245 . The exhaust system may include the vacuum pump  246 . The exhaust pipe  231  is not limited to being installed at the reaction pipe  203 , but may be installed at the manifold  209  in the same manner as the nozzles  249   a  and  249   b.    
     A seal cap  219 , which serves as a furnace opening lid configured to be capable of hermetically sealing a lower end opening of the manifold  209 , is installed under the manifold  209 . The seal cap  219  is configured to contact the lower end of the manifold  209  from the lower side in the vertical direction. The seal cap  219  is made of, for example, a metal material such as SUS and is formed in a disc shape. An O-ring  220   b , which is a seal member making contact with the lower end of the manifold  209 , is installed at an upper surface of the seal cap  219 . A rotation mechanism  267  configured to rotate a boat  217  to be described below is installed at the opposite side of the seal cap  219  from the process chamber  201 . A rotary shaft  255  of the rotation mechanism  267 , which penetrates the seal cap  219 , is connected to the boat  217 . The rotation mechanism  267  is configured to rotate the wafers  200  by rotating the boat  217 . The seal cap  219  is configured to be vertically moved up or down by a boat elevator  115  which is an elevation mechanism vertically installed outside the reaction tube  203 . The boat elevator  115  is configured to be capable of loading or unloading the boat  217  into or out of the process chamber  201  by moving the seal cap  219  up or down. The boat elevator  115  is configured as a transfer device (a transfer mechanism) which transfers the boat  217 , that is, the wafers  200 , into or out of the process chamber  201 . Further, a shutter  219   s , which serves as a furnace opening lid configured to be capable of hermetically sealing a lower end opening of the manifold  209  while the seal cap  219  is moved down by the boat elevator  115 , is installed under the manifold  209 . The shutter  219   s  is made of, for example, a metal material such as SUS and is formed in a disc shape. An O-ring  220   c , which is a seal member making contact with the lower end of the manifold  209 , is installed at an upper surface of the shutter  219   s . The opening/closing operation (elevation operation, rotation operation, and the like) of the shutter  219   s  is controlled by a shutter opening/closing mechanism  115   s.    
     (Substrate Support) 
     As illustrated in  FIG. 1 , the boat  217  serving as a substrate support is configured to support a plurality of wafers  200 , for example, 25 to 200 wafers, in such a state that the wafers  200  are arranged in a horizontal posture and in multiple stages along a vertical direction with the centers of the wafers  200  aligned with one another. As such, the boat  217  is configured to arrange the wafers  200  to be spaced apart from each other. The boat  217  is made of a heat resistant material such as quartz or SiC. Heat insulating plates  218  made of a heat resistant material such as quartz or SiC are supported in multiple stages below the boat  217 . 
     As illustrated in  FIG. 2 , a temperature sensor  263  serving as a temperature detector is installed in the reaction tube  203 . Based on temperature information detected by the temperature sensor  263 , a state of supplying electric power to the heater  207  is regulated such that the interior of the process chamber  201  has a desired temperature distribution. The temperature sensor  263  is installed along the inner wall of the reaction tube  203  in the same manner as the nozzles  249   a  and  249   b.    
     (Control Device) 
     Next, a control device will be described with reference to  FIG. 5 . As illustrated in  FIG. 5 , a controller  121 , which is a control part (control device), may be configured as a computer including a central processing unit (CPU)  121   a , a random access memory (RAM)  121   b , a memory  121   c , and an I/O port  121   d . The RAM  121   b , the memory  121   c , and the I/O port  121   d  are configured to be capable of exchanging data with the CPU  121   a  via an internal bus  121   e . An input/output device  122  formed of, for example, a touch panel or the like, is connected to the controller  121 . 
     The memory  121   c  includes, for example, a flash memory, a hard disk drive (HDD), and the like. A control program that controls operations of a substrate processing apparatus, a process recipe, in which sequences and conditions of a film-forming process to be described below are written, and the like are readably stored in the memory  121   c . The process recipe functions as a program configured to cause the controller  121  to execute each sequence in various types of processes (film-forming processes) to be described below, to obtain an expected result. Hereinafter, the process recipe and the control program may be generally and simply referred to as a “program.” Further, the process recipe may be simply referred to as a “recipe.” When the term “program” is used herein, it may indicate a case of including the recipe only, a case of including the control program only, or a case of including both the recipe and the control program. The RAM  121   b  is configured as a memory area (work area) in which a program or data read by the CPU  121   a  is temporarily stored. 
     The I/O port  121   d  is connected to the MFCs  241   a  to  241   d , the valves  243   a  to  243   d , the pressure sensor  245 , the APC valve  244 , the vacuum pump  246 , the heater  207 , the temperature sensor  263 , the matching device  272 , the high frequency power supply  273 , the rotation mechanism  267 , the boat elevator  115 , the shutter opening/closing mechanism  115   s , and the like. 
     The CPU  121   a  is configured to read and execute the control program from the memory  121   c . The CPU  121   a  also reads the recipe from the memory  121   c  according to an input of an operation command from the input/output device  122 . The CPU  121   a  is configured to control the rotation mechanism  267 , the flow rate regulating operation of various types of gases by the MFCs  241   a  to  241   d , the opening/closing operation of the valves  243   a  to  243   d , the regulating operation of the high frequency power supply  273  based on impedance monitoring, the opening/closing operation of the APC valve  244 , the pressure regulating operation performed by the APC valve  244  based on the pressure sensor  245 , the actuating and stopping of the vacuum pump  246 , the temperature regulating operation performed by the heater  207  based on the temperature sensor  263 , the forward/backward rotation, rotation angle and rotation speed adjustment operation of the boat  217  by the rotation mechanism  267 , the operation of moving the boat  217  up or down by the boat elevator  115 , and the like, according to contents of the read recipe. 
     The controller  121  may be configured by installing, on the computer, the aforementioned program stored in an external memory  123  (for example, a magnetic disk such as a HDD, an optical disc such as a CD, a magneto-optical disc such as a MO, or a semiconductor memory such as a USB memory). The memory  121   c  and the external memory  123  are configured as a computer-readable recording medium. Hereinafter, the memory  121   c  and the external memory  123  may be generally and simply referred to as a “recording medium.” When the term “recording medium” is used herein, it may indicate a case of including the memory  121   c  only, a case of including the external memory  123  only, or a case of including both the memory  121   c  and the external memory  123 . Further, the program may be provided to the computer by using communication means such as the Internet or a dedicated line, instead of using the external memory  123 . 
     (2) Substrate Processing Process 
     Next, as a process of manufacturing a semiconductor device, a process of forming a thin film on a wafer  200  by using a substrate processing apparatus will be described with reference to  FIGS. 6 and 7 . In the following descriptions, operations of various parts constituting the substrate processing apparatus are controlled by the controller  121 . 
     Here, an example will be described in which a silicon nitride film (SiN film) is formed, as a film containing Si and N, on a wafer  200  by, non-simultaneously, that is, without being synchronized, a predetermined number of times (one or more times), performing a step of supplying a DCS gas as a precursor gas and a step of supplying a plasma-excited NH 3  gas as a reaction gas. For example, a predetermined film may be formed in advance on the wafer  200 . A predetermined pattern may be formed in advance on the wafer  200  or the predetermined film. 
     In the present disclosure, for the sake of convenience, the film-forming process flow illustrated in  FIG. 7  may be denoted as follows. The same notation will be used in description of modifications and other embodiments to be described below. 
       (DCS→NH 3 *)× n ⇒SiN
 
     When the term “wafer” is used in the present disclosure, it may refer to “a wafer itself” or “a wafer and a laminated body of certain layers or films formed on a surface of the wafer”. When the phrase “a surface of a wafer” is used in the present disclosure, it may refer to “a surface of a wafer itself” or “a surface of a certain layer formed on a wafer”. When the expression “a certain layer is formed on a wafer” is used in the present disclosure, it may mean that “a certain layer is formed directly on a surface of a wafer itself” or that “a certain layer is formed on a layer formed on a wafer”. When the term “substrate” is used in the present disclosure, it may be synonymous with the term “wafer.” 
     (Loading Step: S 1 ) 
     When a plurality of wafers  200  is charged on the boat  217  (wafer charging), the shutter  219   s  is moved by the shutter opening/closing mechanism  115   s  and the lower end opening of the manifold  209  is opened (shutter open). Thereafter, as illustrated in  FIG. 1 , the boat  217  supporting the plurality of wafers  200  is lifted up by the boat elevator  115  to be loaded into the process chamber  201  (boat loading). In this state, the seal cap  219  seals the lower end of the manifold  209  via the O-ring  220   b.    
     (Pressure and Temperature Regulating Step: S 2 ) 
     The interior of the process chamber  201 , that is, the space in which the wafers  200  are placed, is vacuum-exhausted (depressurization-exhausted) by the vacuum pump  246  to reach a desired pressure (degree of vacuum). In this operation, the internal pressure of the process chamber  201  is measured by the pressure sensor  245 . The APC valve  244  is feedback-controlled based on the measured pressure information. The vacuum pump  246  keeps operating at least until a film-forming step to be described below is completed. 
     In addition, the wafers  200  in the process chamber  201  are heated by the heater  207  to a desired temperature. In this operation, the state of supplying electric power to the heater  207  is feedback-controlled based on the temperature information detected by the temperature sensor  263  such that the interior of the process chamber  201  has a desired temperature distribution. The heating of the interior of the process chamber  201  by the heater  207  is continuously performed at least until the film-forming step to be described below is completed. However, when the film-forming step is performed under temperature condition of equal to or lower than room temperature, the heating of the interior of the process chamber  201  by the heater  207  may not be performed. In the case where only the process at such a temperature is performed, the heater  207  may not be used, whereby the heater  207  may not be installed in the substrate processing apparatus. This may simplify the configuration of the substrate processing apparatus. 
     Subsequently, rotation of the boat  217  and the wafer  200  by the rotation mechanism  267  is started. The rotation of the boat  217  and the wafer  200  by the rotation mechanism  267  is continuously performed at least until the film-forming step is completed. 
     (Film-Forming Step: S 3 , S 4 , S 5 , and S 6 ) 
     Then, steps S 3 , S 4 , S 5 , and S 6  are sequentially executed to perform a film-forming step. 
     (Precursor Gas Supplying Step: S 3 ) 
     At the step S 3 , a DCS gas is supplied to the wafer  200  in the process chamber  201 . 
     The valve  243   a  is opened to allow the DCS gas to flow through the gas supply pipe  232   a . A flow rate of the DCS gas is regulated by the MFC  241   a , and the DCS gas is supplied from the first ejection holes  250   a  and the second ejection holes  250   b  into the process chamber  201  via the nozzle  249   a  and is exhausted through the exhaust pipe  231 . At the same time, the valve  243   c  is opened to allow a N 2  gas to flow through the gas supply pipe  232   c . A flow rate of the N 2  gas is regulated by the MFC  241   c , and the N 2  gas is supplied into the process chamber  201  together with the DCS gas and is exhausted through the exhaust pipe  231 . 
     In addition, the valves  243   d  is opened to allow a N 2  gas to flow through the gas supply pipe  232   d  to prevent the DCS gas from infiltrating into the nozzle  249   b . The N 2  gas is supplied into the process chamber  201  via the gas supply pipe  232   b  and the nozzle  249   b  and is exhausted through the exhaust pipe  231 . 
     A supply flow rate of the DCS gas, which is controlled by the MFC  241   a , is set to fall within a range of, for example, 1 to 6,000 sccm, specifically 2,000 to 3,000 sccm in some embodiments. A supply flow rate of the N 2  gas, which is controlled by the MFCs  241   c  and  241   d , are set to fall within a range of, for example, 100 to 10,000 sccm. The internal pressure of the process chamber  201  is set to fall within a range of, for example, 1 to 2,666 Pa, specifically 665 to 1,333 Pa in some embodiments. A supply time for the DCS gas is set to a range of, for example, 1 to 10 seconds, specifically 1 to 3 seconds in some embodiments. Further, a supply time for the N 2  gas is set to a range of, for example, 1 to 10 seconds, specifically 1 to 3 seconds in some embodiments. 
     The temperature of the heater  207  is set such that the temperature of the wafer  200  falls within a range of, for example, 0 to 700 degrees C., specifically room temperature (25 degrees C.) to 550 degrees C., more specifically 40 to 500 degrees C. in some embodiments. As in the embodiments, an amount of heat applied to the wafer  200  can be reduced by setting the temperature of the wafer  200  to 700 degrees C. or less, specifically 550 degrees C. or less, and more specifically 500 degrees C. or less, whereby a heat history suffered by the wafer  200  may be controlled appropriately. 
     By supplying the DCS gas to the wafer  200  under the aforementioned conditions, a Si-containing layer is formed on the wafer  200  (surface base film). The Si-containing layer may include Cl or H, in addition to a Si layer. The Si-containing layer is formed on the outermost surface of the wafer  200  when DCS is physically adsorbed, a substance obtained by partial decomposition of DCS is chemically adsorbed, or Si is deposited by thermal decomposition of DCS. That is, the Si-containing layer may be an adsorption layer (physical adsorption layer or chemical adsorption layer) of DCS or a substance obtained by partial decomposition of DCS, or a Si deposition layer (Si layer). 
     After the Si-containing layer is formed, the valve  243   a  is closed to stop the supply of the DCS gas into the process chamber  201 . At this time, with the APC valve  244  kept open, the interior of the process chamber  201  is vacuum-exhausted by the vacuum pump  246  to remove the unreacted DCS gas, the DCS gas having contributed to the formation of the Si-containing layer, or reaction by-products remaining in the process chamber  201  from the process chamber  201 . 
     (Purge Gas Supplying Step: S 4 ) 
     Further, at this time, the supply of the N 2  gas into the process chamber  201  is maintained while the valves  243   c  and  243   d  remain open. The N 2  gas acts as a purge gas. Since the nozzle  249   a  connected to the valve  243   c  includes the first ejection holes  250   a  and the second ejection holes  250   b , the purge gas is supplied (ejected) not only to the wafer  200  supported by the boat  217  but also to the inner wall of the reaction tube  203  (S 4 ). A supply flow rate of the N 2  gas controlled by the MFC  241   c  at this time is set to fall within a range of, for example, 1,000 to 5,000 sccm. At this time, a supply flow rate of the N 2  gas supplied by the first ejection holes  250   a  of the nozzle  249   a  is set to fall within a range of, for example, 900 to 4,500 sccm. Further, a supply flow rate of the N 2  gas supplied by the second ejection holes  250   b  of the nozzle  249   a  is set to fall within a range of, for example, 100 to 500 sccm. The relationship between the supply flow rates of the N 2  gas from the first ejection holes  250   a  and the second ejection holes  250   b  may be regulated by the number of installation and the opening diameters of the first ejection holes  250   a  and second ejection holes  250   b . For example, in a case where the number of installation of the first ejection holes  250   a  and the second ejection holes  250   b  has a ratio of 2.5:1 and the opening diameters of the first ejection holes  250   a  and second ejection holes  250   b  have a ratio of 2:1, the supply flow rate of the N 2  gas may be set to have the above-mentioned relationship. 
     That is, here, the N 2  gas (inert gas) as the purge gas is supplied from the first ejection holes  250   a  to the wafer  200  and is supplied from the second ejection holes  250   b  to the inner wall of the reaction tube  203 . This step is performed after stop of the supply of the DCS gas as the precursor gas and before start of the supply of the reaction gas to be described below, that is, between the precursor gas supplying step and the reaction gas supplying step. At this time, the flow rate of the N 2  gas supplied from the first ejection holes  250   a  is larger than the flow rate of the N 2  gas supplied from the second ejection holes  250   b , as described above. 
     As the precursor gas, in addition to the DCS gas, it may be possible to appropriately use, for example, various aminosilane precursor gases such as a tetrakisdimethylaminosilane (Si[N(CH 3 ) 2 ] 4 , abbreviation: 4DMAS) gas, a trisdimethylaminosilane (Si[N(CH 3 ) 2 ] 3 H, abbreviation: 3DMAS) gas, a bisdimethylaminosilane (Si[N(CH 3 ) 2 ] 2 H 2 , abbreviation: BDMAS) gas, a bisdiethylaminosilane (Si[N(C 2 H 5 ) 2 ] 2 H 2 , abbreviation: BDEAS) gas, a bistertiarybutylaminosilane (SiH 2 [NH(C 4 H 9 )] 2 , abbreviation: BTBAS) gas, a dimethylaminosilane (DMAS) gas, a diethylaminosilane (DEAS) gas, a dipropylaminosilane (DPAS) gas, a diisopropylaminosilane (DIPAS) gas, a butylaminosilane (BAS) gas, a hexamethyldisilazane (HMDS) gas, and the like, inorganic halosilane precursor gases such as a monochlorosilane (SiH 3 Cl, abbreviation: MCS) gas, a trichlorosilane (SiHCl 3 , abbreviation: TCS) gas, a tetrachlorosilane (SiCl 4 , abbreviation: STC) gas, a hexachlorodisilane (Si 2 Cl 6 , abbreviation: HCDS) gas, an octachlorotrisilane (Si 3 Cl 8 , abbreviation: OCTS) gas, and the like, and halogen group-free inorganic silane precursor gases such as a monosilane (SiH 4 , abbreviation: MS) gas, a disilane (Si 2 H 6 , abbreviation: DS) gas, a trisilane (Si 3 H 8 , abbreviation: TS) gas, and the like. 
     Examples of the inert gas may include rare gases such as an Ar gas, a He gas, a Ne gas, a Xe gas, and the like, in addition to the N 2  gas. 
     (Reaction Gas Supplying Step: S 5 ) 
     After the precursor gas supplying step is completed, a plasma-excited NH 3  gas as a reaction gas is supplied to the wafer  200  in the process chamber  201  (S 5 ). 
     In this step, the opening/closing control of the valves  243   b  to  243   d  is performed in the same procedure as the opening/closing control of the valves  243   a ,  243   c , and  243   d  in the step S 3 . A flow rate of the NH 3  gas is regulated by the MFC  241   b , and the NH 3  gas is supplied into the buffer chamber  237  via the nozzle  249   b . At this time, high frequency power is supplied among the rod-shaped electrodes  269 ,  270 , and  271 . The NH 3  gas supplied into the buffer chamber  237  is excited into a plasma state (converted into plasma and activated), supplied as active species (NH 3 *) into the process chamber  201 , and exhausted via the exhaust pipe  231 . 
     The supply flow rate of the NH 3  gas, which is controlled by the MFC  241   b , is set to fall within a range of, for example, 100 to 10,000 sccm, specifically 1,000 to 2,000 sccm in some embodiments. The high frequency power applied to the rod-shaped electrodes  269 ,  270 , and  271  is set to fall within a range of, for example, 50 to 600 W. The internal pressure of the process chamber  201  is set to fall within a range of, for example, 1 to 500 Pa. By using plasma, the NH 3  gas can be activated even when the internal pressure of the process chamber  201  is set to such a relatively low pressure zone. The time during which the active species obtained by plasma-excitation of the NH 3  gas is supplied to the wafer  200 , that is, the gas supply time (irradiation time), is set to fall within a range of, for example, 1 to 180 seconds, specifically 1 to 60 seconds in some embodiments. Other process conditions are the same as those in the step S 3  described above. 
     By supplying the NH 3  gas to the wafer  200  under the aforementioned conditions, the Si-containing layer formed on the wafer  200  is plasma-nitrided. At this time, the Si—Cl bond and Si—H bond of the Si-containing layer are cut by an energy of the plasma-excited NH 3  gas. Cl and H de-bonded from Si are desorbed from the Si-containing layer. Then, Si in the Si-containing layer, which has a dangling bond due to desorption of Cl or the like, is bonded to N contained in the NH 3  gas to form a Si—N bond. As this reaction proceeds, the Si-containing layer can be changed (modified) into a layer containing Si and N, that is, a silicon nitride layer (SiN layer). 
     The NH 3  gas may be plasma-excited and then supplied to modify the Si-containing layer into the SiN layer. This is because, even when the NH 3  gas is supplied in a non-plasma atmosphere, an energy to nitride the Si-containing layer is insufficient in the above-mentioned temperature zone, and accordingly, it is difficult to increase the Si—N bond by sufficiently desorbing Cl and H from the Si-containing layer or sufficiently nitriding the Si-containing layer. 
     After the Si-containing layer is changed into the SiN layer, the valve  243   b  is closed to stop the supply of the NH 3  gas. Further, the supply of the high frequency power among the rod-shaped electrodes  269 ,  270 , and  271  is stopped. Then, the NH 3  gas and reaction by-products remaining in the process chamber  201  are removed from the process chamber  201  according to the same processing procedure and process conditions as in the step S 4 . 
     (Purge Gas Supplying Step: S 6 ) 
     Then, also at this time, as in the case of the step S 4 , a N 2  gas (inert gas) as a purge gas is supplied from the first ejection holes  250   a  to the wafer  200  and is supplied from the second ejection holes  250   b  to the inner wall of the reaction tube  203 . This step is performed after the supply of the plasma-excited NH 3  gas as the reaction gas is stopped, that is, after the step of supplying the reaction gas is performed. At this time, the flow rate of the N 2  gas supplied from the first ejection holes  250   a  is larger than the flow rate of the N 2  gas supplied from the second ejection holes  250   b , as described above. 
     As a nitriding agent, that is, a NH 3 -containing gas to be plasma-excited, in addition to the NH 3  gas, it may be possible to use, for example, a diazene (N 2 H 2 ) gas, a hydrazine (N 2 H 4 ) gas, a N 3 H 8  gas, or the like. 
     As an inert gas, for example, various rare gases exemplified in the step S 4  may be used in addition to the N 2  gas. 
     (Performing Predetermined Number of Times: S 7 ) 
     A cycle that non-simultaneously, that is, asynchronously, performs the steps S 3 , S 4 , S 5 , and S 6  is performed in this order a predetermined number of times (n times), that is, one or more times (S 7 ), to thereby form a SiN film having a predetermined composition and a predetermined film thickness on the wafer  200 . The aforementioned cycle may be performed multiple times. That is, a thickness of the SiN layer formed per one cycle may be set to be smaller than a desired film thickness. Thus, the aforementioned cycle may be performed multiple times until a film thickness of the SiN film formed by laminating the SiN layers becomes equal to the desired film thickness in some embodiments. 
     After the predetermined number of times (n times) of cycles (see “n th  cycle” in  FIG. 7 ) is completed, the opening/closing control of the valve  243   c  may be then performed to eject a N 2  gas (inert gas) as a purge gas from each of the first ejection holes  250   a  and the second ejection holes  250   b  in the nozzle  249   a  for a predetermined time. In that case, it is possible to shorten at least one selected from the group of the time during which the N 2  gas is supplied in the step S 4  and the time during which the N 2  gas is supplied in the step S 6 , as compared with a case where there is no supply of the inert gas after completion of the cycle. 
     (Returning to Atmospheric Pressure Step: S 8 ) 
     After the aforementioned film-forming process is completed, a N 2  gas as an inert gas is supplied into the process chamber  201  from each of the gas supply pipes  232   c  and  232   d  and is exhausted via the exhaust pipe  231 . Thus, the interior of the process chamber  201  is purged with the inert gas to remove a gas and the like remaining in the process chamber  201  from the interior of the process chamber  201  (inert gas purge). The internal atmosphere of the process chamber  201  is then substituted with the inert gas (inert gas substitution) and the internal pressure of the process chamber  201  is returned to an atmospheric pressure (S 8 ). 
     (Unloading Step: S 9 ) 
     Then, the seal cap  219  is moved down by the boat elevator  115  to open the lower end of the manifold  209 . In addition, the processed wafers  200  supported by the boat  217  are unloaded from the lower end of the manifold  209  to the outside of the reaction tube  203  (boat unloading) (S 9 ). After the boat unloading, the shutter  219   s  is moved, and the lower end opening of the manifold  209  is sealed by the shutter  219   s  via the O-ring  220   c  (shutter closing). After being unloaded from the reaction tube  203 , the processed wafers  200  are discharged from the boat  217  (wafer discharging). After the wafer discharging, an empty boat  217  may be loaded into the process chamber  201 . 
     (3) Effects According to the Embodiments 
     According to the embodiments, one or more effects set forth below may be achieved. 
     (a) According to the embodiments, the nozzle  249   a  includes the first ejection holes  250   a  and the second ejection holes  250   b , and the N 2  gas (inert gas) as the purge gas is supplied (ejected) from the first ejection holes  250   a  to the wafer  200  and is supplied (ejected) from the second ejection holes  250   b  to the inner wall of the reaction tube  203 . That is, the N 2  gas (inert gas) as the purge gas is supplied (ejected) not only to the wafer  200  but also to the inner wall of the reaction tube  203 . Therefore, at the same time when the wafer  200  is purged, the inner wall of the reaction tube  203  is also purged, thereby effectively preventing reaction by-products from adhering to the inner wall of the reaction tube  203 . When the generation of deposits on the inner wall of the reaction tube  203  can be suppressed, the generation of foreign substances (particles) caused by the deposits (reaction by-products, and the like) can also be suppressed, thereby avoiding quality deterioration of processing on the wafer  200  in advance. 
     (b) According to the embodiments, since an installation interval (second predetermined interval) of the second ejection holes  250   b  is wider than an installation interval (first predetermined interval) of the first ejection holes  250   a , the flow rate of the N 2  gas (inert gas) as the purge gas supplied from the first ejection holes  250   a  is larger than the flow rate of the N 2  gas (inert gas) as the purge gas supplied from the second ejection holes  250   b . In other words, the deposits on the inner wall of the reaction tube  203  can be efficiently removed with a flow rate smaller than the flow rate of the purge gas ejected toward the center of the wafer  200 . Therefore, even when the wafer  200  and the inner wall of the reaction tube  203  are purged, each purging can be efficiently performed with an appropriate gas flow rate. 
     (c) According to the embodiments, the first ejection holes  250   a  and the second ejection holes  250   b  are formed at positions opposite to each other. Therefore, it is possible to effectively purge a back side of the nozzle  249   a  when viewed from the wafer  200 &#39;s side, that is, a portion where a gas collects between the nozzle  249   a  and the inner wall of the reaction tube  203 , which is very useful in preventing the generation of deposits on the inner wall of the reaction tube  203 . 
     (First Modification) 
     Next, a first modification of the embodiments will be described with reference to  FIGS. 8A and 8B . In the first modification, only parts different from the aforementioned embodiments will be described below, and description of the same parts will be omitted. 
     In the aforementioned embodiments, the nozzle  249   a  having a configuration in which the second ejection holes  250   b  are formed at positions opposite to the first ejection holes  250   a  has been described in detail, but in the present first modification, as the second ejection holes  250   b , a plurality of ejection holes having different ejection directions are formed in the nozzle  249   a . Therefore, the N 2  gas (inert gas) for the inner wall of the reaction tube  203  is supplied (ejected) from the plurality of second ejection holes  250   b  having different ejection directions. 
     In the first modification, the second ejection holes  250   b  are formed at, for example, two places. In that case, it is assumed that an angle θ formed by the ejection direction of the second ejection holes  250   b  of each of the two places and the direction along the first ejection holes  250   a  falls within a range of 45 degrees to 90 degrees (see  FIG. 8B ). In a case where the angle θ is less than 45 degrees, an effect of purging on the inner wall of the reaction tube  203  is substantially the same as a case where only one second ejection holes  250   b  is formed (that is, the case of the aforementioned embodiments). Further, in a case where the angle θ exceeds 90 degrees, the efficiency of removing the deposits on the back side of the nozzle  249   a  may decrease. When the angle θ falls within the range of 45 degrees to 90 degrees, it is possible to efficiently remove the deposits on the inner wall of the reaction tube  203  over a wide range while enabling effective purging on the back side of the nozzle  249   a.    
     As described above, according to the first modification, the N 2  gas (inert gas) as the purge gas is supplied (ejected) from the plurality of second ejection holes  250   b  having different ejection directions to the inner wall of the reaction tube  203 . Therefore, the deposits on the inner wall of the reaction tube  203  can be efficiently removed over a wide range. Further, it is possible to effectively purge the back side of the nozzle  249   a , that is, a portion where a gas collects between the nozzle  249   a  and the inner wall of the reaction tube  203 . 
     (Second Modification) 
     Next, a second modification of the embodiments will be described with reference to  FIG. 9 . Also in the second modification, only parts different from the aforementioned embodiments will be described below, and description of the same parts will be omitted. 
     In the second modification, the first ejection holes  250   a  and the second ejection holes  250   b  are formed at positions having different heights with respect to the height direction of the nozzle  249   a . That is, unlike the case of the aforementioned embodiments (see  FIG. 3 ), none of the second ejection holes  250   b  is formed at the same height as the first ejection holes  250   a.    
     In this way, according to the second modification, the positions of the first ejection holes  250   a  and the second ejection holes  250   b  are different from each other in the height direction of the nozzle  249   a . Therefore, it may be easier to control the flow rate of the purge gas supplied (ejected) from the first ejection holes  250   a  and the second ejection holes  250   b , as compared with the case of the basic configuration in the aforementioned embodiments (see  FIG. 3 ). That is, it may be suitable for efficiently purging the wafer  200  and the inner wall of the reaction tube  203  with an appropriate gas flow rate. 
     (Third Modification) 
     Next, a third modification of the embodiments will be described with reference to  FIG. 10 . Also in the third modification, only parts different from the aforementioned embodiments will be described below, and description of the same parts will be omitted. 
     In the third modification, a nozzle  249   a - 1  configured to supply a N 2  gas (inert gas) as a purge gas and a nozzle  249   a - 2  configured to supply a DCS gas (precursor gas) as a process gas are arranged in the reaction tube  203 , as separate bodies. That is, unlike the case of the aforementioned embodiments in which the nozzle  249   a  is shared in supplying the process gas and supplying the purge gas (see  FIGS. 1 and 2 ), the nozzle  249   a - 1  configured to supply the purge gas is installed in the reaction tube  203 , separately from the nozzle  249   a - 2  configured to supply the process gas (however, an inert gas as a carrier gas may be supplied together). 
     The first ejection holes  250   a  and the second ejection holes  250   b  are formed in the nozzle  249   a - 1  configured to supply the purge gas. The second ejection holes  250   b  are arranged at a positions opposite to the first ejection holes  250   a . However, as in the aforementioned first modification, the second ejection holes  250   b  may be arranged at a plurality of locations having different ejection directions. Further, as in the aforementioned second modification, the first ejection holes  250   a  and the second ejection holes  250   b  may be arranged at positions having different heights with respect to the height direction of the nozzle  249   a - 1 . 
     According to the third modification having such a configuration, since the nozzle  249   a - 1  have the first ejection holes  250   a  and the second ejection holes  250   b , the N 2  gas (inert gas) as the purge gas is supplied (ejected) not only to the wafer  200  but also to the inner wall of the reaction tube  203 . Therefore, at the same time when purging the wafer  200 , the inner wall of the reaction tube  203  is also purged, thereby effectively preventing reaction by-products from adhering to the inner wall of the reaction tube  203 . 
     Further, according to the third modification, since the nozzle  249   a - 1  configured to supply the purge gas is installed separately from the nozzle  249   a - 2  configured to supply the process gas, a versatility of control of supplying the purge gas may be improved and control contents may be optimized, as compared with the case of the aforementioned embodiments (that is, the case where the nozzle is shared). 
     OTHER EMBODIMENTS OF THE PRESENT DISCLOSURE 
     Some embodiments of the present disclosure have been described in detail above. However, the present disclosure is not limited to the aforementioned embodiments but may be variously modified without departing from the gist of the present disclosure. 
     For example, examples in which the reaction gas is supplied after the precursor gas is supplied have been described in the above-described embodiments. However, the present disclosure is not limited to such embodiments, but a supply order of the precursor gas and the reaction gas may be reversed. That is, the precursor gas may be supplied after the reaction gas is supplied. By changing the supply order, a film quality and a composition ratio of a film to be may be changed. 
     Further, configuration examples including the plasma generation part that excites (activates) the reaction gas into the plasma state have been described in the aforementioned embodiments. However, the present disclosure is not limited to such embodiments but may also be applied to a substrate processing apparatus with no plasma generation part. That is, the plasma generation part (buffer chamber) may be included, and even in a case where a substrate processing apparatus does not include the plasma generation part, the present disclosure may be applied to the substrate processing apparatus as long as the substrate processing apparatus includes a dedicated nozzle configured to supply a purge gas. 
     Further, examples in which the SiN film is formed on the wafer  200  have been described in the aforementioned embodiments and the like. The present disclosure is not limited to such embodiments but may be suitably applied to a case of forming a Si-based oxide film such as a silicon oxide film (SiO film), a silicon oxycarbide film (SiOC film), a silicon oxycarbonitride film (SiOCN film), and a silicon oxynitride film (SiON film) on the wafer  200 , and a case of forming a Si-based nitride film such as a silicon carbonitride film (SiCN film), a silicon boronitride film (SiBN film), a silicon borocarbonitride film (SiBCN film), and a borocarbonitride film (BCN film) on the wafer  200 . In these cases, in addition to the O-containing gas, a C-containing gas such as C 3 H 6 , a N-containing gas such as NH 3 , or a B-containing gas such as BCl 3  may be used as the reaction gas. 
     In addition, the present disclosure may also be suitably applied to a case of forming an oxide film or a nitride film containing a metal element such as titanium (Ti), zirconium (Zr), hafnium (Hf), tantalum (Ta), niobium (Nb), aluminum (Al), molybdenum (Mo), and tungsten (W), that is, a metal-based oxide film or a metal-based nitride film, on the wafer  200 . That is, the present disclosure may also be suitably applied to a case of forming a TiO film, a TiN film, a TiOC film, a TiOCN film, a TiON film, a TiBN film, a TiBCN film, a ZrO film, a ZrN film, a ZrOC film, a ZrOCN film, a ZrON film, a ZrBN film, a ZrBCN film, a HfO film, a HfN film, a HfOC film, a HfOCN film, a HfON film, a HfBN film, a HfBCN film, a TaO film, a TaOC film, a TaOCN film, a TaON film, a TaBN film, a TaBCN film, a NbO film, a NbN film, a NbOC film, a NbOCN film, a NbON film, a NbBN film, a NbBCN film, an AlO film, an AlN film, an AlOC film, an AlOCN film, an AlON film, an AlBN film, an AlBCN film, a MoO film, a MoN film, a MoOC film, a MoOCN film, a MoON film, a MoBN film, a MoBCN film, a WO film, a WN film, a WOC film, a WOCN film, a WON film, a MWBN film, a WBCN film, or the like on the wafer  200 . 
     In these cases, as the precursor gas, it may be possible to use, for example, a tetrakis(dimethylamino)titanium (Ti[N(CH 3 ) 2 ] 4 , abbreviation: TDMAT) gas, a tetrakis(ethylmethylamino)hafnium (Hf[N(C 2 H 5 )(CH 3 )] 4 , abbreviation: TEMAH) gas, a tetrakis(ethylmethylamino)zirconium (Zr[N(C 2 H 5 )(CH 3 )] 4 , abbreviation: TEMAZ) gas, a trimethylaluminum (Al(CH 3 ) 3 , abbreviation: TMA) gas, a titaniumtetrachloride (TiCl 4 ) gas, a hafniumtetrachloride (HfCl 4 ) gas, or the like. As the reaction gas, the aforementioned reaction gas may be used. 
     That is, the present disclosure can be suitably applied to a case of forming a half metal-based film containing a half metal element or a metal-based film containing a metal element. The processing procedures and process conditions of this film-forming process may be the same as those of the film-forming processes described in the aforementioned embodiments and modifications. Even in this case, the same effects as those of the aforementioned embodiments and modifications can be obtained. 
     Recipes used in the film-forming process may be provided individually according to the processing contents and may be stored in the memory  121   c  via a telecommunication line or the external memory  123  in some embodiments. Moreover, at the beginning of various types of processes, the CPU  121   a  may properly select an appropriate recipe from the recipes stored in the memory  121   c  according to the contents of the processing in some embodiments. Thus, it is possible for a single substrate processing apparatus to form films of various types, composition ratios, qualities, and thicknesses for general purpose and with enhanced reproducibility. In addition, it is possible to reduce an operator&#39;s burden and to quickly start the various types of processes while avoiding an operation error. 
     The recipes mentioned above are not limited to newly-provided ones but may be provided, for example, by modifying existing recipes that are already installed in the substrate processing apparatus. Once the recipes are modified, the modified recipes may be installed in the substrate processing apparatus via a telecommunication line or a recording medium storing the recipes. In addition, the existing recipes already installed in the substrate processing apparatus may be directly modified by operating the input/output device  122  of the substrate processing apparatus. 
     According to some embodiments of the present disclosure, it is possible to provide a technique capable of preventing generation of deposits on an inner wall of a reaction tube. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosures. Indeed, the embodiments described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the disclosures. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosures.