Patent Publication Number: US-2021183670-A1

Title: Substrate processing apparatus, substrate retainer and method of manufacturing semiconductor device

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION 
     This non-provisional U.S. patent application claims priority under 35 U.S.C. § 119 of International Application No. PCT/JP2018/033861, filed on Sep. 12, 2018, in the WIPO, the entire contents of which are hereby incorporated by reference. 
    
    
     FIELD 
     The present disclosure relates to a substrate processing apparatus, a substrate retainer and a method of manufacturing a semiconductor device. 
     DESCRIPTION OF THE RELATED ART 
     As a part of manufacturing processes of a semiconductor device, a substrate processing (for example, a film-forming process) may be performed by supplying a process gas to a substrate accommodated in a process vessel of a substrate processing apparatus. When the substrate processing described above is performed, a part of the process gas may be adsorbed (adhered) to an inner wall or other location of the process vessel. 
     For example, according to some related arts, a technique of suppressing the generation of a foreign substance in the process vessel is disclosed. 
     The foreign substance in the process vessel may adhere to an inner wall of a reaction tube, may be remained on the inner wall of the reaction tube, or may be accumulated below the reaction tube. It is preferable to efficiently remove the foreign substance. 
     SUMMARY 
     Described herein is a technique capable of efficiently removing a foreign substance in a reaction tube. 
     Other problems and novel features of the technique described herein will become apparent from the descriptions of the present specification and the accompanying drawings. 
     The following is a brief overview of a representative one of the present disclosure. 
     That is, according to one aspect of the technique of the present disclosure, there is provided a substrate processing apparatus including: a reaction tube in which a substrate is processed; and a substrate retainer including a plurality of support columns configured to support the substrate, wherein at least one among the plurality of the support columns includes: a hollow portion through which an inert gas is supplied; and a gas supply port through which the inert gas is supplied toward an inner wall of the reaction tube. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically illustrates a vertical cross-section of a vertical type process furnace of a substrate processing apparatus preferably used in one or more embodiment described herein. 
         FIG. 2  schematically illustrates a horizontal cross-section taken along the line A-A of the vertical type process furnace of the substrate processing apparatus preferably used in the embodiments shown in  FIG. 1 . 
         FIG. 3A  is an enlarged cross-sectional view for explaining a buffer structure of the substrate processing apparatus preferably used in the embodiments described herein, and  FIG. 3B  is a schematic diagram for explaining the buffer structure of the substrate processing apparatus preferably used in the embodiments described herein. 
         FIG. 4  is a block diagram schematically illustrating a configuration of a controller and related components of the substrate processing apparatus preferably used in the embodiments described herein. 
         FIG. 5  is a flow chart schematically illustrating a substrate processing according to the embodiments described herein. 
         FIG. 6  is a timing diagram schematically illustrating a gas supply used in the substrate processing according to the embodiments described herein. 
         FIG. 7  schematically illustrates a horizontal cross-section of the vertical type process furnace shown in  FIG. 2  with a boat loaded according to the embodiment described herein. 
         FIG. 8  schematically illustrates a vertical cross-section of the vertical type process furnace with the boat loaded according to the embodiment described herein. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, one or more embodiments (also simply referred to as “embodiments”) according to the technique of the present disclosure will be described with reference to the drawings. Like reference numerals represent like components in the drawings, and redundant descriptions related thereto will be omitted. In the drawings, for the sake of convenience of the descriptions, features may be schematically illustrated as compared with actual features. However, the drawings are merely examples of the embodiments, and the embodiments according to the technique of the present disclosure are not limited thereto. 
     Embodiment 
     Hereinafter, an embodiment according to the technique of the present disclosure will be described with reference to  FIGS. 1 through 8 . 
     (1) Configuration of Substrate Processing Apparatus (Heating Apparatus) 
     As shown in  FIG. 1 , for example, a substrate processing apparatus  100  according to the present embodiment includes a vertical type process furnace (also simply referred to as a “process furnace”)  202  capable of accommodating a plurality of substrates in a multistage manner in a vertical direction. The process furnace  202  includes a heater  207  serving as a heating apparatus (heating structure). The heater  207  is of a cylinder shape, and is vertically installed while being supported by a heater base (not shown) serving as a support plate. As described later, the heater  207  also functions as an activator (which is an activation structure) or an exciter (which is an excitation structure) capable of activating (or exciting) a gas such as a source gas and a reactive gas by heat. 
     &lt;Process Chamber&gt; 
     A reaction tube  203  is provided at an inner side of the heater  207  to be aligned in a manner concentric with the heater  207 . For example, the reaction tube  203  is made of a heat resistant material such as quartz (SiO 2 ), silicon carbide (SiC) and silicon nitride (SiN). The reaction tube  203  is of a cylinder shape with a closed upper end and an open lower end. A manifold (which is an inlet flange)  209  is provided under the reaction tube  203  to be aligned in a manner concentric with the reaction tube  203 . The manifold  209  is made of a metal such as stainless steel (SUS). The manifold  209  is of a cylinder shape with open upper and lower ends. The upper end of the manifold  209  is engaged with the lower end of the reaction tube  203  so as to support the reaction tube  203 . An O-ring  220   a  serving as a seal is provided between the manifold  209  and the reaction tube  203 . As the manifold  209  is supported by the heater base (not shown), the reaction tube  203  is installed vertically. A process vessel (also referred to as a “reaction vessel”) is constituted mainly by the reaction tube  203  and the manifold  209 . A process chamber  201  is provided in a hollow cylindrical portion of the process vessel. The process chamber  201  is configured to accommodate a plurality of wafers including a wafer  200  serving as a substrate. The process vessel is not limited to the configuration described above. For example, the reaction tube  203  alone may be referred to as the process vessel. 
     &lt;Gas Supplier&gt; 
     Nozzles  249   a  and  249   b  are provided in the process chamber  201  so as to penetrate a side wall of the manifold  209 . Gas supply pipes  232   a  and  232   b  are connected to the nozzles  249   a  and  249   b,  respectively. As described above, the two nozzles  249   a  and  249   b  and the two gas supply pipes  232   a  and  232   b  are provided in the reaction tube  203 , and various gases may be supplied into the process chamber  201  via the two nozzles  249   a  and  249   b  and the two gas supply pipes  232   a  and  232   b.    
     Mass flow controllers  241   a  and  241   b  serving as flow rate controllers (flow rate control structures) and valves  243   a  and  243   b  serving as opening/closing valves are sequentially installed at the gas supply pipes  232   a  and  232   b,  respectively, from upstream sides to downstream sides of the gas supply pipes  232   a  and  232   b.  Hereinafter, a mass flow controller is also referred to as an “MFC”. 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  of the gas supply pipes  232   a  and  232   b,  respectively. MFCs  241   c  and  241   d  and valves  243   c  and  243   d  are sequentially installed at the gas supply pipes  232   c  and  232   d,  respectively, from upstream sides to downstream sides of the gas supply pipes  232   c  and  232   d.    
     As shown in  FIG. 2 , the nozzle  249   a  is installed in a space between an inner wall of the reaction tube  203  and the plurality of the wafers including the wafer  200  accommodated in the process chamber  201 , and extends from a lower portion of the inner wall of the reaction tube  203  to an upper portion of the inner wall of the reaction tube  203  along a stacking direction of the plurality of the wafers. That is, the nozzle  249   a  is provided adjacent to edges (peripheral portions) of the plurality of the wafers accommodated in the process chamber  201 . In other words, the nozzle  249   a  is provided perpendicularly to surfaces (flat surfaces) of the plurality of the wafers. A plurality of gas supply holes  250   a  configured to supply the gas are provided at a side surface of the nozzle  249   a.  The gas supply holes  250   a  are open toward a center of the reaction tube  203 , and are configured to supply the gas toward the plurality of the wafers accommodated in the process chamber  201 . The gas supply holes  250   a  are provided from a lower portion of the reaction tube  203  to an upper portion of the reaction tube  203 . The opening areas of the gas supply holes  250   a  are equal to one another, and the gas supply holes  250   a  are provided at the same pitch. 
     The nozzle  249   b  is connected to a front end of the gas supply pipe  232   b.  The nozzle  249   b  is provided in a buffer chamber  237  serving as a gas dispersion space. As shown in  FIG. 2 , the buffer chamber  237  is installed in an annular space between the inner wall of the reaction tube  203  and the plurality of the wafers including the wafer  200  accommodated in the process chamber  201  when viewed from above, and extends from the lower portion of the inner wall of the reaction tube  203  to the upper portion of the inner wall of the reaction tube  203  along the stacking direction of the plurality of the wafers. That is, the buffer chamber  237  is defined by a buffer structure  300  provided in a region that horizontally surrounds a wafer arrangement region where the plurality of the wafers are arranged along the stacking direction of the plurality of the wafers. The buffer structure  300  is made of an insulating material such as quartz. A plurality of gas supply ports  302  and a plurality of gas supply ports  304 , through which the gas is supplied, are provided on an arc-shaped wall surface of the buffer structure  300 . As shown in  FIGS. 2 and 3 , the gas supply ports  302  and the gas supply ports  304  are provided to face a plasma generation region  224   a  between rod-shaped electrodes  269  and  270  described later and a plasma generation region  224   b  between rod-shaped electrodes  270  and  271  described later, respectively. The gas supply ports  302  and the gas supply ports  304  are open toward the center of the reaction tube  203  to supply the gas toward the plurality of the wafers accommodated in the process chamber  201 . The gas supply ports  302  and the gas supply ports  304  are provided from the lower portion of the reaction tube  203  to the upper portion of the reaction tube  203 . The opening areas of the gas supply ports  302  are equal to one another, and the gas supply ports  302  are provided at the same pitch. The opening areas of the gas supply ports  304  are equal to one another, and the gas supply ports  304  are provided at the same pitch. 
     The nozzle  249   b  is provided in the buffer structure  300  adjacent to the region that horizontally surrounds the wafer arrangement region where the plurality of the wafers are arranged along the stacking direction of the plurality of the wafers. That is, the nozzle  249   b  is provided adjacent to the edges (the peripheral portions) of the plurality of the wafers accommodated in the process chamber  201 . In other words, the nozzle  249   b  is provided perpendicularly to the surfaces (the flat surfaces) of the plurality of the wafers. A plurality of gas supply holes  250   b  configured to supply the gas are provided at a side surface of the nozzle  249   b.  The gas supply holes  250   b  are open toward a wall surface of the buffer structure  300  provided along a radial direction with respect to the arc-shaped wall surface of the buffer structure  300 , and are configured to supply the gas toward the wall surface of the buffer structure  300 . As a result, the reactive gas is dispersed (diffused) in the buffer chamber  237 , and is not directly sprayed onto the rod-shaped electrodes  269  through  271 . Therefore, it is possible to suppress the generation of particles. The gas supply holes  250   b  are provided from the lower portion to the upper portion of the reaction tube  203 . 
     According to the present embodiment, the gas such as the source gas and the reactive gas are supplied through the nozzles  249   a  and  249   b  and the buffer chamber  237 , which are provided in the vertical annular space (that is, a cylindrical space) when viewed from above defined by an inner surface of a side wall (that is, the inner wall) of the reaction tube  203  and the edges of the plurality of the wafers including the wafer  200  arranged in the reaction tube  203 . Then, the gas is ejected into the reaction tube  203  in the vicinity of the plurality of the wafers through the gas supply holes  250   a  and the gas supply holes  250   b  of the nozzles  249   a  and  249   b,  respectively, and the gas supply ports  302  and the gas supply ports  304  of the buffer chamber  237 . The gas ejected into the reaction tube  203  mainly flows parallel to the surfaces of the plurality of the wafers, that is, in a horizontal direction. Thereby, it is possible to uniformly supply the gas to each of the plurality of the wafers and to improve a thickness uniformity of a film formed on each of the plurality of the wafers. After passing the surfaces of the plurality of the wafers, the gas (for example, a residual gas remaining after the reaction) flows toward an exhaust port, that is, toward an exhaust pipe  231  described later. However, a flow direction of the gas may vary depending on the location of the exhaust port, and is not limited to the vertical direction. 
     The source gas containing a predetermined element is supplied into the process chamber  201  through the gas supply pipe  232   a  provided with the MFC  241   a  and the valve  243   a  and the nozzle  249   a.  For example, a silane source gas containing silicon (Si) as the predetermined element may be used as the source gas. 
     In the present specification, the term “source gas” may refer to a source material in a gaseous state under the normal temperature and the normal pressure (atmospheric pressure) or a gas obtained by vaporizing a source material in a liquid state (that is, a liquid source) under the normal temperature and the normal pressure. In the present specification, the term “source material” may indicate only “source material in a liquid state”, may indicate only “source material (source gas) in a gaseous state” and may indicate both of “source material in the liquid state” and “source material in the gaseous state”. 
     A source gas containing silicon (Si) and a halogen element, that is, a halosilane source gas may be used as the silane source gas. A halosilane source material refers to a silane source material containing a halogen group. The halogen group includes at least one halogen element selected from the group consisting of chlorine (Cl), fluorine (F), bromine (Br) and iodine (I). That is, the halosilane source material may include at least one halogen group selected from the group consisting of a chloro group, a fluoro group, a bromo group and an iodo group. The halosilane source material may be considered as a halide. 
     For example, a source gas containing silicon (Si) and chlorine (Cl), that is, a chlorosilane source gas may be used as the halosilane source gas. For example, dichlorosilane (SiH 2 Cl 2 , abbreviated to DCS) gas may be used as the chlorosilane source gas. 
     The reactive gas serving as a reactant containing an element different from the predetermined element is supplied into the process chamber  201  through the gas supply pipe  232   b  provided with the MFC  241   b  and the valve  243   b  and the nozzle  249   b.  For example, a nitrogen (N)-containing gas may be used as the reactive gas. As the nitrogen-containing gas, for example, a hydrogen nitride-based gas may be used. The hydrogen nitride-based gas may also be referred to as a substance constituted by two elements of nitrogen (N) and hydrogen (H) without any other elements. The hydrogen nitride-based gas serves as a nitriding gas, that is, a nitrogen source material. For example, ammonia (NH 3 ) gas may be used as the hydrogen nitride-based gas. 
     The inert gas such as nitrogen (N 2 ) gas is supplied into the process chamber  201  through the gas supply pipes  232   c  and  232   d  provided with the MFCs  241   c  and  241   d  and the valves  243   c  and  243   d,  respectively, the gas supply pipes  232   a  and  232   b  and the nozzles  249   a  and  249   b.    
     For example, a source gas supply system serving as a first gas supply system is constituted mainly by the gas supply pipe  232   a,  the MFC  241   a,  the valve  243   a,  and a reactive gas supply system (which is a reactant supply system) serving as a second gas supply system is constituted mainly by the gas supply pipe  232   b,  the MFC  241   b  and the valve  243   b.  An inert gas supply system is constituted mainly by 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 source gas supply system, the reactive gas supply system and the inert gas supply system may be collectively referred to as a process gas supply system (or a process gas supplier or a gas supplier). Further, the source gas and the reactive gas may be collectively referred to as the process gas. 
     &lt;Plasma Generator&gt; 
     As illustrated in  FIGS. 2 and 3 , in the buffer chamber  237 , three rod-shaped electrodes  269 ,  270  and  271  made of a conductor and formed as an elongated thin and long structure are provided from the lower portion to the upper portion of the reaction tube  203  along the stacking direction of the plurality of the wafers including the wafer  200 . Each of the rod-shaped electrodes  269 ,  270  and  271  is provided parallel to the nozzle  249   b.  Each of the rod-shaped electrodes  269 ,  270  and  271  is covered and protected by an electrode protecting pipe  275  from an upper portion to a lower portion thereof. The rod-shaped electrode  270  is connected to and grounded to the electrical ground serving as a reference potential, and the two rod-shaped electrodes  269  and  271  of the three rod-shaped electrodes  269 ,  270  and  271  disposed at both sides of the rod-shaped electrode  270  are connected to a high frequency power supply  273  through a matcher  272  (which is a matching structure). That is, the rod-shaped electrodes  269  and  271  connected to the high frequency power supply  273  and the rod-shaped electrode  270  connected to the electrical ground are alternately arranged, and the rod-shaped electrode  270  provided between the rod-shaped electrodes  269  and  271  serves as a common ground for the rod-shaped electrodes  269  and  271 . In other words, the rod-shaped electrode  270  connected to the electrical ground is disposed between the rod-shaped electrodes  269  and  271 , and the rod-shaped electrodes  269  and  270  and the rod-shaped electrodes  271  and  270  respectively form pairs to generate plasma. That is, the rod-shaped electrode  270  connected to the electrical ground is commonly used for the two rod-shaped electrodes  269  and  271  adjacent to the rod-shaped electrode  270  and connected to the high frequency power supply  273 . By applying high frequency power (that is, RF power) to the rod-shaped electrodes  269  and  271  from the high frequency power supply  273 , the plasma is generated in the plasma generation region  224   a  between the rod-shaped electrodes  269  and  270  and in the plasma generation region  224   b  between the rod-shaped electrodes  270  and  271 . A plasma generator (which is a plasma generating apparatus) capable of generating the plasma in the plasma generation regions  224   a  and  224   b  is constituted mainly by the rod-shaped electrodes  269 ,  270  and  271 , the electrode protecting pipe  275 . The plasma generator serves as a plasma source. The plasma generator may further include the matcher  272  and the high frequency power supply  273 . As described later, the plasma generator (plasma source) also functions as an activator (which is an activation structure) or an exciter (which is an excitation structure) capable of activating (or exciting) the gas to the plasma (that is, into a plasma state). 
     The electrode protecting pipe  275  is configured to insert each of the rod-shaped electrodes  269 ,  270  and  271  into the buffer chamber  237  in a state of being isolated from an inner atmosphere of the buffer chamber  237 . If an oxygen (O 2 ) concentration of an inside of the electrode protecting pipe  275  is set to the same level as an oxygen concentration of an outside air (an air atmosphere), each of the rod-shaped electrodes  269 ,  270  and  271  inserted into the electrode protecting pipe  275  may be oxidized by the heat of the heater  207 . Therefore, by charging the inside of the electrode protecting pipe  275  with the inert gas such as the N 2  gas or by purging the inside of the electrode protecting pipe  275  with the inert gas such as the N 2  gas using an inert gas purge apparatus, it is possible to lower the oxygen concentration of the inside of the electrode protecting pipe  275 . Thereby, it is possible to suppress the oxidation of the rod-shaped electrodes  269 ,  270  and  271 . 
     &lt;Exhauster&gt; 
     The exhaust pipe  231  configured to exhaust an inner atmosphere of the process chamber  201  is provided at the reaction tube  203 . A vacuum pump  246  serving as a vacuum exhaust apparatus is connected to the exhaust pipe  231  through a pressure sensor  245  and an APC (Automatic Pressure Controller) valve  244 . The pressure sensor  245  serves as a pressure detector (pressure detection device) to detect an inner pressure of the process chamber  201 , and the APC valve  244  serves as an exhaust regulator (pressure regulator). With the vacuum pump  246  in operation, the APC valve  244  may be opened or closed to vacuum-exhaust the process chamber  201  or stop the vacuum exhaust. With the vacuum pump  246  in operation, an opening degree of the APC valve  244  may be adjusted based on pressure information detected by the pressure sensor  245 , in order to control (adjust) the inner pressure of the process chamber  201 . An exhaust system (also referred to as an “exhauster”) is constituted mainly by the exhaust pipe  231 , the APC valve  244  and the pressure sensor  245 . The exhaust system may further include the vacuum pump  246 . The present embodiment is not limited to an example in which the exhaust pipe  231  is provided at the reaction tube  203 . For example, similar to the nozzles  249   a  and  249   b,  the exhaust pipe  231  may be provided at the manifold  209  instead of the reaction tube  203 . 
     A seal cap  219  serving as a furnace opening lid capable of airtightly sealing a lower end opening of the manifold  209  is provided under the manifold  209 . The seal cap  219  is in contact with the lower end of the manifold  209  from thereunder. The seal cap  219  is made of a metal such as SUS (stainless steel), and is of a disk shape. An O-ring  220   b  serving as a seal provided on an upper surface of the seal cap  219  so as to be in contact with the lower end of the manifold  209 . A rotator  267  configured to rotate a boat  217  described later is provided under the seal cap  219  opposite to the process chamber  201 . A rotating shaft  255  of the rotator  267  is connected to the boat  217  through the seal cap  219 . As the rotator  267  rotates the boat  217 , the plurality of the wafers including the wafer  200  supported by the boat  217  are rotated. That is, the rotator  267  is configured to rotate the plurality of the wafers including the wafer  200 . A boat elevator  115  serving as an elevator is provided outside the reaction tube  203  vertically. The seal cap  219  may be elevated or lowered in the vertical direction by the boat elevator  115 . When the seal cap  219  is elevated or lowered by the boat elevator  115 , the boat  217  placed on the seal cap  219  may be transferred (loaded) into the process chamber  201  or transferred (unloaded) out of the process chamber  201 . The boat elevator  115  serves as a transfer device (or a transport device) capable of loading the boat  217  (that is, the plurality of the wafers including the wafer  200  accommodated in the boat  217 ) into the process chamber  201  or unloading the boat  217  (that is, the plurality of the wafers including the wafer  200  accommodated in the boat  217 ) out of the process chamber  201 . A shutter  219   s  serving as a furnace opening lid capable of airtightly sealing the lower end opening of the manifold  209  is provided under the manifold  209 . The shutter  219   s  is configured to close the lower end opening of the manifold  209  when the seal cap  219  is lowered by the boat elevator  115 . The shutter  219   s  is made of a metal such as SUS (stainless steel), and of a disk shape. An O-ring  220   c  serving as a seal is provided on an upper surface of the shutter  219   s  so as to be in contact with the lower end of the manifold  209 . An opening/closing operation of the shutter  219   s  such as an elevation operation and a rotation operation is controlled by a shutter opener/closer (which is a shutter opening/closing structure)  115   s.    
     &lt;Substrate Retainer&gt; 
     As shown in  FIG. 1 , the boat  217  (which is a substrate retainer) is configured to align the plurality of the wafers including the wafer  200 , for example, from 25 to 200 wafers in the vertical direction and configured to support the plurality of the wafers in a multistage manner, while the plurality of the wafers are horizontally oriented with their centers aligned with each other. That is, the boat  217  supports (accommodates) the plurality of the wafers including the wafer  200  with a predetermined interval therebetween. The boat  217  is made of a heat resistant material such as quartz and SiC. A plurality of insulating plates  218  are provided under the boat  217  in a multistage manner. 
     As shown in  FIG. 2 , a temperature sensor  263  serving as a temperature detector is provided in the reaction tube  203 . The state of electric conduction to the heater  207  is adjusted based on temperature information detected by the temperature sensor  263  such that a desired temperature distribution of the inner temperature of the process chamber  201  can be obtained. Similar to the nozzles  249   a  and  249   b,  the temperature sensor  263  is provided along the inner wall of the reaction tube  203 . 
       FIG. 7  schematically illustrates a horizontal cross-section of the vertical type process furnace  202  shown in  FIG. 2  with the boat  217  loaded according to the present embodiment.  FIG. 8  schematically illustrates a vertical cross-section of the vertical type process furnace  202  with the boat  217  loaded according to the present embodiment. 
     As shown in  FIGS. 7 and 8 , the boat  217  includes a pair of end plates (an upper end plate  30  and a lower end plate  31 ) and a plurality of support columns (which are boat columns, for example, three support columns  32   a,    32   b  and  32   c ) provided between the upper end plate  30  and the lower end plate  31  to connect the upper end plate  30  and the lower end plate  31 . The boat  217  may further include the rotator  267 . As such, the boat  217  and the rotator  267  may be collectively referred to as the substrate retainer. A plurality of support recesses  33  are engraved at each of the three support columns  32   a,    32   b  and  32   c  at equal intervals in a lengthwise direction of each of the three support columns  32   a,    32   b  and  32   c.  The support recesses  33  engraved at the same stage of each of the three support columns  32   a,    32   b  and  32   c  are open to face one another. By inserting the plurality of the wafers including the wafer  200  to the support recesses  33  engraved at the same stage of each of the three support columns  32   a,    32   b  and  32   c,  the boat  217  supports the plurality of the wafers vertically arranged in a multistage manner while the plurality of the wafers are horizontally oriented with their centers aligned with one another. The three support columns  32   a ,  32   b  and  32   c  are made of an insulating material such as quartz. 
     A hollow portion (which serves as a gas supply tube)  35  through which the inert gas is supplied and a plurality of gas supply ports  36  through which the inert gas (purge gas) is supplied (ejected) toward the inner wall of the reaction tube  203  are provided at at least one among the three support columns  32   a,    32   b,    32   c  provided with the support recesses  33 . The plurality of the gas supply ports  36  may also be referred to as the gas supply ports  36 . For example, the hollow portion  35  and the gas supply ports  36  are provided at the support column  32   a.  The gas supply ports  36  are open toward the inner wall of the reaction tube  203 , and are configured to supply the inert gas (“PG 1 ” shown in  FIGS. 7 and 8 ) toward the inner wall of the reaction tube  203 . The gas supply ports  36  are provided from the lower portion of the reaction tube  203  to the upper portion of the reaction tube  203 . The opening areas of the gas supply ports  36  are equal to one another, and the gas supply ports  36  are provided at the same pitch. Thereby, it possible to supply the inert gas to regions  203   a  and  203   b  on the inner wall of the reaction tube  203  where a foreign substance (by-products) is likely to adhere or remain. Further, it is also possible to effectively remove the foreign substance adhered to or remaining in the regions  203   a  and  203   b  on the inner wall of the reaction tube  203 . 
     For example, the rotator  267  includes: the rotating shaft  255  configured to rotate the boat  217  in a boat rotating direction (“BR” shown in  FIG. 7 ); a rotating table  256  configured to hold the boat  217  (for example, the three support columns  32   a,    32   b  and  32   c ); and gas supply pipes (also referred to as “inert gas supply pipes” or “purge gas supply pipes”)  38   a  and  38   b  configured to supply the inert gas to the boat  217  provided with the hollow portion  35 . The gas supply pipe (also referred to as a “first gas supply pipe”)  38   a  installed at the rotating shaft  255  is provided at a rotation center (“BRC” shown in  FIG. 8 ) of the rotating shaft  255 . The gas supply pipe (also referred to as a “second gas supply pipe”)  38   b  installed at the rotating table  256  is provided so as to connect the gas supply pipe  38   a  provided at a center (that is, the rotation center) of the rotating shaft  255  and the hollow portion  35  of the boat  217 . 
     A gas supply pipe (also referred to as an “inert gas supply pipe” or a “purge gas supply pipe”)  38   c  configured to supply the inert gas is provided at an inlet adapter  209   a  configured to hold the reaction tube  203 , the boat elevator  115  serving as a boat elevating structure and the rotator  267 . 
     For example, the inert gas is supplied to the hollow portion  35  of the boat  217  through the gas supply pipe  38   a  of the rotating shaft  255  and the gas supply pipe  38   b  of the rotating table  256  via the inlet adapter  209   a,  the boat elevator  115  and the rotator  267 , and is ejected from the gas supply ports (which are openings)  36  of the boat  217  to the inner wall of the reaction tube  203  at a predetermined flow rate. 
     By rotating the boat  217  in the boat rotating direction BR by the rotator  267 , it is possible to supply the purge gas PG 1  to the entire inner wall of the reaction tube  203  including the regions  203   a  and  203   b  where the foreign substance (by-products) is likely to adhere or remain. 
     With respect to the pitch (opening pitch) of the gas supply ports  36  provided in the support column  32   a,  in order to supply a constant flow rate of the inert gas to the inner wall of the reaction tube  203 , the opening pitch may be widened when a distance between the inner wall of the reaction tube  203  and each of the three support columns  32   a,    32   b  and  32   c  is short, and the opening pitch may be narrowed when the distance between the inner wall of the reaction tube  203  and each of the three support columns  32   a,    32   b  and  32   c  is long. 
     A gas supply port  37  is proved at the rotating shaft  255 . The gas supply port  37  is configured to supply the purge gas to the manifold (inlet flange)  209  and/or the inlet adapter  209   a  provided under the reaction tube  203 . Thereby, it possible to remove the by-products deposited (or accumulated) below the reaction tube  203 . 
     The gas supply ports  36  and the gas supply port  37  may be of circular or elliptical shape. 
     &lt;Controller&gt; 
     Hereinafter, a controller  121  will be described with reference to  FIG. 4 . As shown in  FIG. 4 , the controller  121  serving as a control device (control structure) is constituted by a computer including a CPU (Central Processing Unit)  121   a,  a RAM (Random Access Memory)  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  may exchange data with the CPU  121   a  through an internal bus  121   e.  For example, an input/output device  122  such as a touch panel is connected to the controller  121 . 
     The memory  121   c  is configured by components such as a flash memory and a hard disk drive (HDD). For example, a control program configured to control the operation of the substrate processing apparatus  100  or a process recipe containing information on the sequences and conditions of a substrate processing such as a film-forming process described later is readably stored in the memory  121   c.  The process recipe is obtained by combining steps of the substrate processing such as the film-forming process described later such that the controller  121  can execute the steps to acquire a predetermine result, and functions as a program. Hereafter, the process recipe and the control program may be collectively or individually referred to as a “program”. In addition, the process recipe may also be simply referred to as a “recipe”. In the present specification, the term “program” may indicate only the process recipe, may indicate only the control program, or may indicate both of the process recipe and the control program. The RAM  121   b  functions as a memory area (work area) where a program or data read by the CPU  121   a  is temporarily stored. 
     The I/O port  121   d  is connected to the above-described components such as the mass flow controllers (MFCs)  241   a,    241   b,    241   c  and  241   d,  the valves  243   a,    243   b,    243   c  and  243   d,  the pressure sensor  245 , the APC valve  244 , the vacuum pump  246 , the heater  207 , the temperature sensor  263 , the matcher  272 , the rotator  267 , the boat elevator  115  and the shutter opener/closer  115   s.    
     The CPU  121   a  is configured to read a control program from the memory  121   c  and execute the read control program. In addition, the CPU  121   a  is configured to read a recipe from the memory  121   c  in accordance with an operation command inputted from the input/output device  122 . According to the contents of the read recipe, the CPU  121   a  may be configured to control various operations such as a control operation of the rotator  267 , flow rate adjusting operations for various gases by the MFCs  241   a,    241   b,    241   c  and  241   d,  opening/closing operations of the valves  243   a ,  243   b,    243   c  and  243   d,  an operation of adjusting the high frequency power supply  273  based on an impedance monitoring, an opening/closing operation of the APC valve  244 , a pressure adjusting operation by the APC valve  244  based on the pressure sensor  245 , a start and stop of the vacuum pump  246 , a temperature adjusting operation of the heater  207  based on the temperature sensor  263 , an operation of adjusting a forward/backward rotation, a rotation angle and a rotation speed of the boat  217  by the rotator  267  and an elevating and lowering operation of the boat  217  by the boat elevator  115 . 
     The controller  121  may be embodied by installing the above-described program stored in an external memory  123  into a computer. For example, the external memory  123  may include a magnetic disk such as a hard disk, an optical disk such as a CD, a magneto-optical disk such as an MO and a semiconductor memory such as a USB memory. The memory  121   c  or the external memory  123  may be embodied by a non-transitory computer readable recording medium. Hereafter, the memory  121   c  and the external memory  123  are collectively or individually referred to as recording media. In the present specification, the term “recording media” may indicate only the memory  121   c,  may indicate only the external memory  123 , and may indicate both of the memory  121   c  and the external memory  123 . Instead of the external memory  123 , a communication means such as the Internet and a dedicated line may be used for providing the program to the computer. 
     (2) Substrate Processing 
     Hereinafter, the substrate processing (that is, the film-forming process) of forming a film on the wafer  200 , which is a part of manufacturing processes of a semiconductor device, will be described with reference to  FIGS. 5 and 6 . Hereinafter, operations of the components constituting the substrate processing apparatus are controlled by the controller  121 . 
     Hereinafter, an example of forming a silicon nitride film (SiN film) serving as a film containing silicon (Si) and nitrogen (N) on the wafer  200  will be described. The SiN film is formed on the wafer  200  by performing a cycle a predetermined number of times (once or more). The cycle includes a step of supplying the DCS gas serving as the source gas onto the wafer  200  and a step of supplying a plasma-excited ammonia (NH 3 ) gas serving as the reactive gas onto the wafer  200 . The steps included in each cycle are performed non-simultaneously. A predetermined film may be formed on the wafer  200  in advance. Further, a predetermined pattern may be formed on the wafer  200  or on the predetermined film in advance. 
     In the present specification, a process flow of the film-forming process shown in  FIG. 6  may be illustrated as follows. 
       (DCS&gt;NH 3 *)× n =&gt;SiN
 
     In the present specification, the term “wafer” may refer to “a wafer itself” or may refer to “a wafer and a stacked structure (aggregated structure) of a predetermined layer (or layers) or a film (or films) formed on a surface of the wafer”. In the present specification, the term “a surface of a wafer” may refer to “a surface of a wafer itself” or may refer to “a surface of a predetermined layer or a film formed on a wafer”. Thus, in the present specification, “forming a predetermined layer (or film) on a wafer” may refer to “forming a predetermined layer (or film) on a surface of a wafer itself” or may refer to “forming a predetermined layer (or film) on a surface of another layer or another film formed on a wafer”. In the present specification, the term “substrate” and “wafer” may be used as substantially the same meaning. That is, the term “substrate” may be substituted by “wafer” and vice versa. 
     &lt;Wafer Charging Step and Boat Loading Step: S 1  and S 2 &gt; 
     The plurality of the wafers including the wafer  200  are transferred into the boat  217  (wafer charging step S 1 ). After the boat  217  is charged with the plurality of the wafers, the shutter  219   s  is moved by the shutter opener/closer  115   s  to open the lower end opening of the manifold  209  (shutter opening step). Then, as shown in  FIG. 1 , the boat  217  charged with the plurality of the wafers is elevated by the boat elevator  115  and transferred into the process chamber  201  (boat loading step S 2 ). With the boat  217  loaded, the seal cap  219  seals the lower end opening of the manifold  209  via the O-ring  220   b.    
     &lt;Pressure and Temperature Adjusting Step: S 3 &gt; 
     The vacuum pump  246  vacuum-exhausts the inner atmosphere of the process chamber  201  until the inner pressure of the process chamber  201  in which the plurality of the wafers including the wafer  200  are accommodated reaches and is maintained at a desired pressure (vacuum degree). In the pressure and temperature adjusting step S 3 , the inner pressure of the process chamber  201  is measured by the pressure sensor  245 , and the APC valve  244  is feedback-controlled based on the measured pressure information (pressure adjusting step). The vacuum pump  246  continuously vacuum-exhausts the inner atmosphere of the process chamber  201  until at least a film-forming step described later is completed. 
     The heater  207  heats the process chamber  201  until the inner temperature of the process chamber  201  reaches and is maintained at a desired temperature. The state of the electric conduction to the heater  207  is feedback-controlled based on the temperature information detected by the temperature sensor  263  such that a desired temperature distribution of the inner temperature of the process chamber  201  can be obtained (temperature adjusting step). The heater continuously heats the process chamber  201  until at least the film-forming step described later is completed. However, when the film-forming step is performed at a temperature equal to or lower than the room temperature, the heating of the process chamber  201  by the heater  207  may be omitted. When the film-forming step is performed only at the temperature equal to or lower than the room temperature, the heater  207  may be omitted and the substrate processing apparatus may be implemented without the heater  207 . In such a case, it is possible to simplify the configuration of the substrate processing apparatus. 
     Then, the rotator  267  rotates the plurality of the wafers including the wafer  200  by rotating the boat  217 . The rotator  267  continuously rotates the boat  217  and the plurality of the wafers accommodated in the boat  217  until at least the film-forming step described later is completed. 
     &lt;Film-Forming Step&gt;Thereafter, the film-forming step is performed by performing the cycle including a source gas supply step S 4 , a purge gas supply step S 5 , a reactive gas supply step S 6  and a purge gas supply step S 7 . 
     &lt;Source Gas Supply Step and Purge Gas Supply Step: S 4  and S 5 &gt; 
     In the step S 4 , the DCS gas is supplied onto the wafer  200  in the process chamber  201 . 
     The valve  243   a  is opened to supply the DCS gas into the gas supply pipe  232   a.  After a flow rate of the DCS gas is adjusted by the MFC  241   a,  the DCS gas whose flow rate is adjusted is supplied into the process chamber  201  through the nozzle  249   a  and the gas supply holes  250   a,  and is exhausted through the exhaust pipe  231 . Simultaneously, the valve  243   c  may be opened to supply the N 2  gas into the gas supply pipe  232   c.  After a flow rate of the N 2  gas is adjusted by the MFC  241   c,  the N 2  gas whose flow rate is adjusted is supplied with the DCS gas into the process chamber  201 , and is exhausted through the exhaust pipe  231 . 
     In order to prevent the DCS gas from entering the nozzle  249   b,  the valve  243   d  may be opened to supply the N 2  gas into the gas supply pipe  232   d.  The N 2  gas is supplied into the process chamber  201  through the gas supply pipe  232   b  and the nozzle  249   b,  and is exhausted through the exhaust pipe  231 . 
     For example, a supply flow rate of the DCS gas adjusted by the MFC  241   a  may be within a range from 1 sccm to 6,000 sccm, preferably from 3,000 sccm to 5,000 sccm. In the present specification, a notation of a numerical range such as “from 1 sccm to 6,000 sccm” means that a lower limit and an upper limit are included in the numerical range. Therefore, for example, a numerical range “from 1 sccm to 6,000 sccm” means a range equal to or higher than 1 sccm and equal to or lower than 6,000 sccm. The same also applies to other numerical ranges described herein. For example, supply flow rates of the N 2  gas adjusted by the MFCs  241   c  and  241   d  may be within a range from 100 sccm to 10,000 sccm, respectively. For example, the inner pressure of the process chamber  201  may be within a range from 1 Pa to 2,666 Pa, preferably from 665 Pa to 1,333 Pa. For example, a time duration of exposing (supplying) the DCS gas onto the wafer  200  may be within a range from 1 second to 10 seconds, preferably from 1 second to 3 seconds. The time duration of exposing the wafer 200 to the DCS gas may vary depending on a thickness of the film. 
     The temperature of the heater  207  is set (adjusted) such that the temperature of the wafer  200  may be within a range from, for example, from 0° C. to 700° C., preferably from the room temperature (25° C.) to 550° C., and more preferably from 40° C. to 500° C. When the temperature of the wafer  200  is maintained at 700° C. or lower, preferably 550° C. or lower, and more preferably 500° C. or lower according to the present embodiment, it is possible to reduce the heat applied to the wafer  200 . Thereby, it is possible to properly control the thermal history of the wafer  200 . 
     By supplying the DCS gas into the process chamber  201  according to the above-described processing conditions, a silicon-containing layer is formed on the wafer  200  (that is, on a base layer formed on the surface of the wafer  200 ). The silicon-containing layer may contain chlorine (Cl) and hydrogen (H) in addition to silicon (Si). The silicon-containing layer may be formed by the physical adsorption of the DCS on a top surface of the wafer  200 , by the chemical adsorption of substances generated by decomposing a part of the DCS on the top surface of the wafer  200 , or by the deposition of silicon generated by the thermal decomposition of the DCS on the top surface of the wafer  200 . That is, the silicon-containing layer may be an adsorption layer (a physical adsorption layer or a chemical adsorption layer) of the DCS or the substances generated by decomposing a part of the DCS, or may be a silicon deposition layer (a silicon layer). 
     After the silicon-containing layer is formed in the step S 4 , the valve  243   a  is closed to stop the supply of the DCS gas into the process chamber  201 . With the APC valve  244  open, the vacuum pump  246  vacuum-exhausts the inner atmosphere of the process chamber  201  to remove a residual DCS gas or reaction byproducts which did not react or which contributed to the formation of the silicon-containing layer from the process chamber  201  (step S 5 ). By maintaining the valves  243   c  and  243   d  open, the N 2  gas is continuously supplied into the process chamber  201 . The N 2  gas serves as a purge gas. The step S 5  is optional and may be omitted. 
     While the DCS gas is exemplified as the source gas in the present embodiment, various gases may be used as the source gas. Instead of the DCS gas, for example, an aminosilane source gas such as tetrakis(dimethylamino)silane (Si[N(CH 3 ) 2 ] 4 , abbreviated as 4DMAS) gas, tris(dimethylamino)silane (Si[N(CH 3 ) 2 ] 3 H, abbreviated as 3DMAS) gas, bis(dimethylamino)silane (Si[N(CH 3 ) 2 ] 2 H 2 , abbreviated as BDMAS) gas and bis(diethylamino)silane (Si[N(C 2 H 5 ) 2 ] 2 H 2 , abbreviated as BDEAS) gas, bis(tertiarybutylamino)silane gas (SiH 2 [NH(C 4 H 9 )] 2 , abbreviated as BTBAS), dimethylaminosilane (DMAS) gas, diethylaminosilane (DEAS) gas, dipropylaminosilane (DPAS) gas, diisopropylaminosilane (DIPAS) gas, butylaminosilane (BAS) gas and hexamethyldisilazane (HMDS) gas may be used as the source gas. Instead of the DCS gas, for example, an inorganic halosilane source gas such as monochlorosilane (SiH 3 Cl, abbreviated as MCS) gas, trichlorosilane (SiHCl 3 , abbreviated as TCS) gas, tetrachlorosilane (SiCl 4 , abbreviated as STC) gas, hexachlorodisilane (Si 2 Cl 6 , abbreviated as HCDS) gas and octachlorotrisilane (Si 3 Cl 8 , abbreviated as OCTS) gas may be used as the source gas. Instead of the DCS gas, for example, an inorganic silane source gas free of halogen such as monosilane (SiH 4 , abbreviated as MS) gas, disilane (Si 2 H 6 , abbreviated as DS) gas and trisilane (Si 3 H 8 , abbreviated as TS) gas may also be used as the source gas. 
     While the N 2  gas is exemplified as the inert gas in the present embodiment, a rare gas such as argon (Ar) gas, helium (He) gas, neon (Ne) gas and xenon (Xe) gas may be used as the inert gas instead of the N 2  gas. 
     &lt;Reactive Gas Supply Step and Purge Gas Supply Step: S 6  and S 7 &gt; 
     After the silicon-containing layer is formed, in the reactive gas supply step, the plasma-excited NH 3  gas serving as the reactive gas is supplied onto the wafer  200  in the process chamber  201  (step S 6 ). 
     In the step S 6 , the opening and the closing of the valves  243   b,    243   c  and  243   d  may be controlled in the same manners as those of the valves  243   a,    243   c  and  243   d  in the step S 4 . After a flow rate of the NH 3  gas is adjusted by the MFC  241   b,  the NH 3  gas whose flow rate is adjusted is supplied into the buffer chamber  237  through the nozzle  249   b.  Simultaneously, the high frequency power is applied to the rod-shaped electrodes  269 ,  270  and  271 . The NH 3  gas supplied into the buffer chamber  237  is excited into the plasma state (activated by the plasma), is supplied into the process chamber  201  as active species NH 3 *, and is exhausted through the exhaust pipe  231 . 
     For example, a supply flow rate of the NH 3  gas adjusted by the MFC  241   b  may be within a range from 100 sccm to 10,000 sccm, preferably from 1,000 sccm to 2,000 sccm. For example, the high frequency power applied to the rod-shaped electrodes  269 ,  270  and  271  may be within a range from 50 W to 600 W. For example, the inner pressure of the process chamber  201  may be within a range from 1 Pa to 500 Pa. By using the plasma, the NH 3  gas is activated even when the inner pressure of the process chamber  201  is relatively low as described above. A time duration of exposing (supplying) the active species obtained by plasma-exciting the NH 3  gas onto the wafer  200  (that is, a gas supply time) may be within a range from 1 second to 180 seconds, preferably from 1 second to 60 seconds. Other processing conditions of the step S 6  are the same as those of the step S 4 . 
     By supplying the NH 3  gas into the process chamber  201  according to the above-described processing conditions, the silicon-containing layer formed on the wafer  200  is plasma-nitrided. During the nitridation, Si—Cl bonds and Si—H bonds included in the silicon-containing layer are broken by the energy of the plasma-excited NH 3  gas. The chlorine (Cl) and hydrogen (H) separated from silicon (Si) are desorbed from the silicon-containing layer. The dangling bond of silicon in the silicon-containing layer produced due to the separation of chlorine and hydrogen enables the bonding of silicon in the silicon-containing layer to nitrogen (N) in the NH 3  gas to form Si—N bonds. As the reaction of forming the Si—N bonds progresses, the silicon-containing layer is changed (modified) into a layer containing silicon and nitrogen, that is, a silicon nitride layer (SiN layer). 
     In order to modify the silicon-containing layer into the SiN layer, it is preferable that the NH 3  gas is plasma-excited and then supplied. When the NH 3  gas is supplied under a non-plasma atmosphere, the energy demanded to nitride the silicon-containing layer may be insufficient at the above-described temperature range. Therefore, it is difficult to fully separate chlorine or hydrogen from the silicon-containing layer or fully nitride the silicon-containing layer to increase the number of the Si—N bonds. 
     After the silicon-containing layer is modified to the SiN layer, the valve  243   b  is closed to stop the supply of the NH 3  gas into the process chamber  201 . The high frequency power applied to the rod-shaped electrodes  269 ,  270  and  271  is also stopped. The NH 3  gas and by-products remaining in the process chamber  201  are removed from the process chamber  201  according to the same sequence and conditions as those of the step S 5  (step S 7 ). The step S 7  is optional and may be omitted. 
     While the NH 3  gas is exemplified as a nitriding agent in the present embodiment, instead of the NH 3  gas, a gas such as diazene (N 2 H 2 ) gas, hydrazine (N 2 H 4 ) gas and N 3 H 8  gas may be used as the nitriding agent, that is, the nitrogen-containing gas excited by the plasma. 
     While the N 2  gas is exemplified as the inert gas in the present embodiment, a rare gas may be used instead of the N 2  gas as the inert gas similar to the step S 4 . 
     &lt;Performing Predetermined Number of Times: S 8 &gt; 
     By performing the cycle wherein the steps S 4 , S 5 , S 6  and S 7  are performed non-simultaneously in order a predetermined number of times (n times), a silicon nitride film (SiN film) of a predetermined composition and a predetermined thickness is formed on the wafer  200  (S 8 ). It is preferable that the cycle is performed a plurality of times. That is, it is preferable that the SiN film of a desired thickness is formed by laminating the SiN layer thinner than the desired thickness by performing the cycle a plurality of times until the desired thickness obtained. 
     &lt;Returning to Atmospheric Pressure Step: S 9 &gt; 
     After the film-forming step described above is completed, the N 2  gas serving as the inert gas is supplied into the process chamber  201  through each of the gas supply pipes  232   c  and  232   d , and then is exhausted through the exhaust pipe  231 . The process chamber  201  is thereby purged with the inert gas such that the gas or the reaction by-products remaining in the process chamber  201  are removed from the process chamber  201  (purging by inert gas). Thereafter, the inner atmosphere of the process chamber  201  is replaced with the inert gas (substitution by inert gas), and the inner pressure of the process chamber  201  is returned to the atmospheric pressure (S 9 ). 
     &lt;Boat Unloading Step and Wafer Discharging Step: S 10  and S 11 &gt; 
     Then, the seal cap  219  is lowered by the boat elevator  115  and the lower end of the manifold  209  is opened. The boat  217  with a plurality of processed wafers including the wafer  200  charged therein is unloaded out of the reaction tube  203  through the lower end of the manifold  209  (boat unloading step S 10 ). After the boat  217  is unloaded, the shutter  219   s  is moved. Thereby, the lower end of the manifold  209  is sealed by the shutter  219   s  through the O-ring  220   c  (shutter closing step). The plurality of the processed wafers including the wafer  200  are taken out of the reaction tube  203 , and then discharged from the boat  217  (wafer discharging step S 11 ). 
     &lt;Performing Film-forming Process Predetermined Number of Times: S 12 &gt; 
     In a step S 12 , it is determined whether or not the film-forming process (that is, the steps S 1  through S 11 ) has been performed a predetermined number of times. When the film-forming process has not been performed the predetermined number of times, the steps S 1  through S 11  are repeatedly performed. When the film-forming process has been performed the predetermined number of times, a purge gas supply step (inert gas supply step) S 15  of purging the inner wall of the reaction tube  203  is performed as described later. For example, the predetermined number of times may be set to 20 times. That is, when the film-forming process is performed 20 times (that is, 20 batches), the purge gas supply step S 15  of purging the inner wall of the reaction tube  203  is performed. The predetermined number of times of the film-forming process may be appropriately determined by a thickness of the by-products deposited on the inner wall of the reaction tube  203 . 
     &lt;Boat Loading Step: S 13 &gt; 
     The shutter  219   s  is moved by the shutter opener/closer  115   s  to open the lower end opening of the manifold  209  (shutter opening step). Then, the boat  217  without accommodating the plurality of the wafers (also referred to as “empty boat  217 ”) is elevated by the boat elevator  115  and transferred into the process chamber  201  (boat loading step S 13 ). With the empty boat  217  loaded, the seal cap  219  seals the lower end opening of the manifold  209  via the O-ring  220   b.    
     &lt;Pressure and Temperature Adjusting Step: S 14 &gt; 
     The vacuum pump  246  vacuum-exhausts the inner atmosphere of the process chamber  201  until the inner pressure of the process chamber  201  reaches and is maintained at a desired pressure (vacuum degree). In the pressure and temperature adjusting step S 14 , the inner pressure of the process chamber  201  is measured by the pressure sensor  245 , and the APC valve  244  is feedback-controlled based on the measured pressure information (pressure adjusting step). The vacuum pump  246  continuously vacuum-exhausts the inner atmosphere of the process chamber  201  until at least the purge gas supply step S 15  of purging the inner wall of the reaction tube  203 , which is described later, is completed. 
     The heater  207  heats the process chamber  201  until the inner temperature of the process chamber  201  reaches and is maintained at a desired temperature. The state of the electric conduction to the heater  207  is feedback-controlled based on the temperature information detected by the temperature sensor  263  such that a desired temperature distribution of the inner temperature of the process chamber  201  can be obtained (temperature adjusting step). The heater continuously heats the process chamber  201  until at least the purge gas supply step S 15  of purging the inner wall of the reaction tube  203 , which is described later, is completed. However, when the purge gas supply step S 15  of purging the inner wall of the reaction tube  203  is performed at a temperature equal to or lower than the room temperature, the heating of the process chamber  201  by the heater  207  may be omitted. 
     Then, the rotator  267  rotates the empty boat  217 . The rotator  267  continuously rotates the empty boat  217  until at least the purge gas supply step S 15  of purging the inner wall of the reaction tube  203 , which is described later, is completed. 
     &lt;Purge Gas Supply Step: S 15 &gt; 
     When the rotator  267  rotates the empty boat  217  at a predetermined speed, the N 2  gas serving as the purge gas (inert gas) is supplied to the hollow portion  35  of the empty boat  217  at a desired supply flow rate, and the N 2  gas is ejected at a predetermined flow rate toward the inner wall of the reaction tube  203  through the gas supply ports  36  provided at the support column  32   a  of the empty boat  217 . Further, the N 2  gas is ejected at a predetermined flow rate toward the manifold (inlet flange)  209  and/or the inlet adapter  209   a  provided under the reaction tube  203  through the gas supply port  37  of the rotating shaft  255 . 
     For example, a process time of purging the inner wall of the reaction tube  203  in the step S 15  may be set to about 5 minutes when the rotation speed of the empty boat  217  is one rotation per minute. Further, the process time of purging the inner wall of the reaction tube  203  in the step S 15  may be appropriately determined based on parameters such as the thickness of the by-products of the inner wall of the reaction tube  203  and the supply flow rate of the purge gas. 
     While the present embodiment is described by way of an example in which the purge gas supply step S 15  of purging the inner wall of the reaction tube  203  is performed after the film-forming process is performed the predetermined number of times, the present embodiment is not limited thereto. For example, the purge gas supply step S 15  of purging the inner wall of the reaction tube  203  may be performed simultaneously with the step S 5  or S 7  of supplying the purge gas in the film-forming process. Further, the purge gas supply step S 15  of purging the inner wall of the reaction tube  203  may be performed simultaneously with a cleaning process of cleaning the inside of the reaction tube  203 . 
     &lt;Returning to Atmospheric Pressure Step: S 16 &gt; 
     After the purge gas supply step S 15  of purging the inner wall of the reaction tube  203  is completed, the inner pressure of the process chamber  201  is returned to the atmospheric pressure (S 16 ). 
     &lt;Boat Unloading Step: S 17 &gt; 
     Then, the seal cap  219  is lowered by the boat elevator  115  and the lower end of the manifold  209  is opened. The empty boat  217  is unloaded out of the reaction tube  203  through the lower end of the manifold  209  (boat unloading step S 17 ). 
     As described above, the present embodiment is described by way of an example in which the substrate processing apparatus  100  is provided with the buffer structure  300 . However, the buffer structure  300  is optional and may be omitted. For example, the present embodiment may also be applied to a substrate processing apparatus without the buffer structure  300 . 
     (3) Effects according to Present Embodiment 
     (a) The hollow portion  35  and the gas supply ports  36 , through which the purge gas is supplied toward the inner wall of the reaction tube  203 , are provided at at least one (for example, at the support column  32   a ) among the three support columns  32   a,    32   b,    32   c.  Thereby, it possible to supply the purge gas to the regions  203   a  and  203   b  on the inner wall of the reaction tube  203  where the foreign substance (the by-products) is likely to adhere or remain. Further, it is also possible to effectively remove the foreign substance adhered to or remaining in the regions  203   a  and  203   b  on the inner wall of the reaction tube  203 . 
     (b) The gas supply port  37  configured to supply the purge gas to the manifold (inlet flange)  209  and/or the inlet adapter  209   a  provided under the reaction tube  203  is provided at the rotating shaft  255 . Thereby, it possible to remove the by-products deposited below the reaction tube  203 . 
     Other Embodiments 
     For example, the above-described embodiment is described by way of an example in which the reactive gas is supplied after the source gas is supplied. However, the above-described technique is not limited thereto. The above-described technique may also be applied when a supply order of the source gas and the reactive gas is changed. That is, the above-described technique may be applied when the source gas is supplied after the reactive gas is supplied. By changing the supply order of the gases, it is possible to change the quality or the composition of the film formed by performing the substrate processing. 
     For example, the above-described embodiment is described by way of an example in which the silicon nitride film (SiN film) on the wafer  200 . However, the above-described technique is not limited thereto. For example, the above-described technique may also be applied to form, on the wafer  200 , a silicon-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). For example, the above-described technique may also be applied to form, on the wafer  200 , a silicon-based nitride film such as a silicon carbonitride film (SiCN film), a silicon boronitride film (SiBN film) and a silicon boron carbonitride film (SiBCN film). In such cases, an oxygen (O)-containing gas, a carbon (C)-containing gas such as C 3 H 6 , a nitrogen (N)-containing gas such as NH 3  and a boron (B)-containing gas such as BCl 3  may be used as the reactive gas to form the above-described films. 
     The above-described technique may also be applied to form, on the wafer  200 , an oxide film (which is a metal-based oxide film) or a nitride film (which is a metal-based 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, the above-described technique may also be applied to form, on the wafer  200 , a film such as 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, and 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 AN 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 WBN film and a WBCN film. 
     For example, various gases such as tetrakis(dimethylamino)titanium (Ti[N(CH 3 ) 2 ] 4 , abbreviated as TDMAT) gas, tetrakis(ethylmethylamino)hafnium (Hf[N(C 2 H 5 )(CH 3 )] 4 , abbreviated as TEMAH) gas, tetrakis(ethylmethylamino)zirconium (Zr[N(C 2 H 5 )(CH 3 )] 4 , abbreviated as TEMAZ) gas, trimethylaluminum (Al(CH 3 ) 3 , abbreviated as TMA) gas, titanium tetrachloride (TiCl 4 ) gas and hafnium tetrachloride (HfCl 4 ) gas may be used as the source gas to form the metal-based oxide film or the metal-based nitride film described above. As the reactive gas, the above-described reactive gas may be used. 
     That is, the above-described technique may also be applied to form a metalloid film containing a metalloid element or a metal-based film containing a metal element. The processing sequences and the processing conditions of the film-forming process of the metalloid film or the metal-based film may be substantially the same as those of the film-forming process according to the embodiment or the modified examples. Even when the above-described technique is applied to the film-forming process of the metalloid film or the metal-based film, it is possible to obtain the same effects as the above-described embodiment or the modified examples. 
     Recipes used in the film-forming process are preferably prepared individually according to the process contents and stored in the memory  121   c  via an electric communication line or the external memory  123 . When starting various processes, the CPU  121   a  is configured to select an appropriate recipe among the recipes stored in the memory  121   c  according to the process contents. Thus, various films of different composition ratios, qualities and thicknesses may be formed in a reproducible manner by using a single substrate processing apparatus. In addition, since the burden on an operator of the substrate processing apparatus may be reduced, various processes may be performed quickly while avoiding a malfunction of the substrate processing apparatus. 
     The above-described recipe is not limited to creating a new recipe. For example, the recipe may be prepared by changing an existing recipe stored in the substrate processing apparatus in advance. When changing the existing recipe to a new recipe, the new recipe may be installed in the substrate processing apparatus via the electric communication line or the recording medium in which the new recipe is stored. The existing recipe already stored in the substrate processing apparatus may be directly changed to a new recipe by operating the input/output device  122  of the substrate processing apparatus. 
     While the technique is described in detail by way of the embodiment and the modified examples, the above-described technique is not limited thereto. The above-described technique may be modified in various ways without departing from the gist thereof. 
     As described above, according to some embodiments in the present disclosure, it is possible to efficiently remove the foreign substance in the reaction tube of the substrate processing apparatus.