Patent Publication Number: US-2021189557-A1

Title: Substrate processing apparatus

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION 
     This non-provisional U.S. patent application claims priority under 35 U.S.C. § 119 of Japanese Patent Application No. 2019-231154, filed on Dec. 23, 2019, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND 
     1. Field 
     The present disclosure relates to a substrate processing apparatus. 
     2. Description of the Related Art 
     A substrate processing apparatus is used to perform a substrate processing which is a part of manufacturing processes of a semiconductor device. For example, the substrate processing apparatus is configured to perform the substrate processing by supplying a process gas to a process chamber where a substrate is accommodated and exhausting the process gas from the process chamber through an exhaust pipe. 
     However, reaction by-products may be deposited in the exhaust pipe of the substrate processing apparatus. Thereby, a conductance of a gas flow may decrease in the exhaust pipe and a pressure gradient in the process chamber may increase. As a result, a uniformity of the substrate processing of the substrate may be deteriorated. 
     SUMMARY 
     Described herein is a technique capable of suppressing a deposition of reaction by-products in an exhaust pipe. 
     According to one aspect of the technique of the present disclosure, there is provided a substrate processing apparatus including: a process chamber where a substrate is processed; a process chamber gas supply system configured to supply a process gas, a purge gas or a cleaning gas into the process chamber; an exhaust pipe configured to perform gas exhaust from the process chamber; an exhaust pipe gas supply system connected to a predetermined deposition risky portion in the exhaust pipe and configured to supply a cleaning contribution gas to the deposition risky portion; and a controller configured to control gas supply through each of the process chamber gas supply system and the exhaust pipe gas supply system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically illustrates a single-wafer type substrate processing apparatus according to a first embodiment described herein. 
         FIG. 2  is a flowchart schematically illustrating a substrate processing according to the first embodiment described herein. 
         FIG. 3  is a flowchart schematically illustrating a film-forming step of the substrate processing shown in  FIG. 2 . 
         FIG. 4  schematically illustrates a single-wafer type substrate processing apparatus according to a third embodiment described herein. 
         FIG. 5  schematically illustrates a multi-wafer type substrate processing apparatus according to a fourth embodiment described herein. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments according to the technique of the present disclosure will be described with reference to the drawings. 
     In the following description, a substrate processing apparatus is an example of an apparatus used to perform a substrate processing in manufacturing processes of a semiconductor device. That is, the substrate processing apparatus is configured to perform a predetermined processing (also referred to as a “substrate processing”) on a substrate to be processed. For example, a silicon wafer (hereinafter, also simply referred to as a “wafer”) serving as a semiconductor substrate on which the semiconductor device is formed may be used as the substrate to be processed. 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 predetermined layers or films formed on a surface of the wafer”. That is, the term “wafer” may collectively refer to “the wafer and the layers or the films formed on the surface of the wafer. In addition, the term “surface of a wafer” may refer to “a surface (exposed surface) of a wafer itself” or may refer to “a surface of a predetermined layer or a film formed on the wafer, i.e. a top surface (uppermost surface) of the wafer as a stacked structure”. In the present specification, the terms “substrate” and “wafer” may be used as substantially the same meaning. For example, as the predetermined processing (substrate processing), a process such as an oxidation process, a diffusion process, an annealing process, an etching process, a pre-cleaning process, a chamber cleaning process and a film-forming process may be performed. Specifically, the embodiments will be described by way of an example in which the film-forming process is performed as the substrate processing. 
     First Embodiment 
     First, a first embodiment according to the technique of the present disclosure will be described in detail. 
     (1) Configuration of Substrate Processing Apparatus 
     Hereinafter, a configuration of a substrate processing apparatus according to the first embodiment will be described. The first embodiment will be described by way of an example in which a single-wafer type substrate processing apparatus configured to process a wafer to be processed one by one is used as the substrate processing apparatus according to the first embodiment.  FIG. 1  schematically illustrates the single-wafer type substrate processing apparatus according to the first embodiment. 
     &lt;Process Vessel&gt; 
     As shown in  FIG. 1 , a substrate processing apparatus  100  according to the first embodiment includes a process vessel  202 . For example, the process vessel  202  is a flat and sealed vessel having a circular horizontal cross-section. The process vessel  202  is made of a metal material such as aluminum (Al) and stainless steel (SUS). The process vessel  202  is constituted by an upper vessel  202   a  and a lower vessel  202   b.  A partition plate  204  is provided between the upper vessel  202   a  and the lower vessel  202   b.    
     A process chamber  201  serving as a process space where a wafer  200  is processed and a transfer chamber  203  serving as a transfer space through which the wafer  200  is transferred into or out of the process chamber  201  are provided in the process vessel  202 . 
     An exhaust buffer chamber  209  is provided in the vicinity of an outer peripheral edge inside the upper vessel  202   a.  The exhaust buffer chamber  209  functions as a buffer space when a gas such as a process gas in the process chamber  201  is exhausted through an outer peripheral portion of the process chamber  201 . Therefore, the exhaust buffer chamber  209  includes a space provided so as to surround the outer peripheral portion of the process chamber  201 . That is, when viewed from above, the exhaust buffer chamber  209  includes the space of a ring shape (annular shape) on the outer peripheral portion of the process chamber  201 . 
     A substrate loading/unloading port  206  is provided on a side surface of the lower vessel  202   b  adjacent to a gate valve  205 . The wafer  200  is transferred (moved) between a vacuum transfer chamber (not shown) and the transfer chamber  203  through the substrate loading/unloading port  206 . Lift pins  207  are provided at a bottom of the lower vessel  202   b.    
     &lt;Substrate Support&gt; 
     A substrate support  210  capable of supporting the wafer  200  is provided in the process chamber  201 . The substrate support  210  mainly includes a substrate support table  212  having a substrate placing surface  211  on which the wafer  200  is placed and a heater  213  serving as a heating source embedded in the substrate support table  212 . Through-holes  214  penetrated by the lift pins  207  are provided at the substrate support table  212  corresponding to the locations of the lift pins  207 . 
     The substrate support table  212  is supported by a shaft  217 . The shaft  217  penetrates the bottom of the process vessel  202 . The shaft  217  is connected to an elevating mechanism  218  outside the process vessel  202 . The wafer  200  placed on the substrate placing surface  211  of the substrate support table  212  may be elevated and lowered by operating the elevating mechanism  218  by elevating and lowering the shaft  217  and the substrate support table  212 . A bellows  219  covers a lower end portion of the shaft  217  to maintain the process chamber  201  airtight. 
     When the wafer  200  is transferred, the substrate support table  212  is moved downward until the substrate placing surface  211  faces the substrate loading/unloading port  206  (that is, the substrate support table  212  is moved to a wafer transfer position). When the wafer  200  is processed, the substrate support table  212  is moved upward until the wafer  200  reaches a processing position (also referred to as a “wafer processing position”) in the process chamber  201  as shown in  FIG. 1 . Specifically, when the substrate support table  212  is lowered to the wafer transfer position, upper end portions of the lift pins  207  protrude from an upper surface of the substrate placing surface  211 , and the lift pins  207  support the wafer  200  from thereunder. When the substrate support table  212  is elevated to the wafer processing position, the lift pins  207  are buried from the upper surface of the substrate placing surface  211 , and the substrate placing surface  211  supports the wafer  200  from thereunder. 
     &lt;Shower Head&gt; 
     A shower head  230  serving as a gas dispersion mechanism is provided at an upper portion of the process chamber  201 . That is, the shower head  230  is provided upstream of the process chamber  201  in reference to a gas supply direction. A gas introduction port  241  is provided at a cover  231  of the shower head  230 . The gas introduction port  241  is configured to communicate with a gas supply system described later. The gas such as the process gas introduced through the gas introduction port  241  is supplied to a buffer space  232  of the shower head  230 . 
     The cover  231  of the shower head  230  is made of a conductive metal. The cover  231  is used as an electrode configured to generate plasma in the buffer space  232  or in the process chamber  201 . An insulating block  233  is provided between the cover  231  and the upper vessel  202   a.  The insulating block  233  electrically insulates the cover  231  from the upper vessel  202   a.    
     The shower head  230  includes a dispersion plate  234  configured to disperse the gas supplied through the gas supply system via the gas introduction port  241 . An upstream side of the dispersion plate  234  is referred to as the buffer space  232 , and a downstream side of the dispersion plate  234  is referred to as the process chamber  201 . The dispersion plate  234  is provided with a plurality of through-holes  234   a.  The dispersion plate  234  is arranged to face the substrate placing surface  211 . 
     &lt;Gas Supply System&gt; 
     A common gas supply pipe  242  is connected to the cover  231  of the shower head  230  so as to communicate with the gas introduction port  241 . The common gas supply pipe  242  communicates with the buffer space  232  in the shower head  230  via the gas introduction port  241 . In addition, a first gas supply pipe  243   a,  a second gas supply pipe  244   a  and a third gas supply pipe  245   a  are connected to the common gas supply pipe  242 . The second gas supply pipe  244   a  is connected to the common gas supply pipe  242  via a remote plasma mechanism (also referred to as a “remote plasma unit” or simply referred to as an “RPU”)  244   e.    
     A source gas, which is one of process gases, is supplied mainly though a source gas supply system  243 . The source gas supply system  243  is a part of the gas supply system, and includes the first gas supply pipe  243   a.  A reactive gas, which is another of the process gases, is supplied mainly though a reactive gas supply system  244  (hereinafter, the source gas and the reactive gas as the process gases may also be collectively or individually referred to as the “process gas”). The reactive gas supply system  244  is a part of the gas supply system, and includes the second gas supply pipe  244   a.  When processing the wafer  200 , an inert gas serving as a purge gas is mainly supplied though a purge gas supply system  245 . The purge gas supply system  245  is a part of the gas supply system, and includes the third gas supply pipe  245   a.  When cleaning the shower head  230  or the process chamber  201 , a cleaning gas is mainly supplied though the purge gas supply system  245 . Among the gases supplied through the gas supply system, the source gas may also be referred to as a “first gas”, the reactive gas may also be referred to as a “second gas”, the inert gas may also be referred to as a “third gas”, and the cleaning gas (for the process chamber  201 ) may also be referred to as a “fourth gas”. The source gas may also be referred to a “first process gas”, and the reactive gas may also be referred to a “second process gas”. In addition, a cleaning contribution gas (for an exhaust pipe  222 ) supplied through an exhaust pipe cleaning contribution gas supply system described later may be referred to as a “fifth gas”. The exhaust pipe cleaning contribution gas supply system is a part of the gas supply system. 
     As described above, the first gas supply pipe  243   a,  the second gas supply pipe  244   a  and the third gas supply pipe  245   a  are connected to the common gas supply pipe  242 . Thereby, the common gas supply pipe  242  is configured to selectively supply the gases such as the source gas (first gas) or the reactive gas (second gas) serving as the process gas, the inert gas (third gas) serving as the purge gas and the cleaning gas (fourth gas) to the process chamber  201  through the buffer space  232  of the shower head  230 . That is, the common gas supply pipe  242  functions as a “first supply pipe” configured to supply the process gas, the purge gas or the cleaning gas to the process chamber  201 . 
     &lt;Source Gas Supply System&gt; 
     A source gas supply source  243   b,  a mass flow controller (MFC)  243   c  serving as a flow rate controller (also referred to as a “flow rate control mechanism”) and a valve  243   d  serving as an opening/closing valve are provided at the first gas supply pipe  243   a  in the sequential order from an upstream side to a downstream side of the first gas supply pipe  243   a.  The source gas is supplied into the shower head  230  via the first gas supply pipe  243   a  provided with the MFC  243   c  and the valve  243   d  and the common gas supply pipe  242 . 
     The source gas (first gas) is one of the process gases. For example, the source gas contains silicon (Si) serving as a first element. Specifically, a gas such as dichlorosilane (SiH 2 Cl 2 , abbreviated as DCS) gas and tetraethoxysilane (Si(OC 2 H 5 ) 4 , abbreviated as TEOS) gas may be used as the source gas. Hereinafter, the first embodiment will be described by way of an example in which the DCS gas is used as the source gas. 
     The source gas supply system  243  is constituted mainly by the first gas supply pipe  243   a,  the MFC  243   c  and the valve  243   d.  The source gas supply system  243  may further include the source gas supply source  243   b  and a first inert gas supply system described later. In addition, since the source gas supply system  243  is configured to supply the source gas which is one of the process gases, the source gas supply system  243  is a part of a process gas supply system. 
     A downstream end of a first inert gas supply pipe  246   a  is connected to the first gas supply pipe  243   a  downstream of the valve  243   d  provided at the first gas supply pipe  243   a.  An inert gas supply source  246   b,  an WC  246   c  and a valve  246   d  are provided at the first inert gas supply pipe  246   a  in the sequential order from an upstream side to a downstream side of the first inert gas supply pipe  246   a.  The inert gas is supplied into the shower head  230  via the first inert gas supply pipe  246   a  provided with the WC  246   c  and the valve  246   d  and the first gas supply pipe  243   a.    
     The inert gas acts as a carrier gas of the source gas. It is preferable that a gas that does not react with the source gas is used as the inert gas. Specifically, for example, nitrogen (N 2 ) gas may be used as the inert gas. Instead of the N 2  gas, for example, a rare gas such as helium (He) gas, neon (Ne) gas and argon (Ar) gas may be used as the inert gas. 
     The first inert gas supply system is constituted mainly by the first inert gas supply pipe  246   a,  the WC  246   c  and the valve  246   d.  The first inert gas supply system may further include the inert gas supply source  246   b  and the first gas supply pipe  243   a.  As described above, the source gas supply system  243  may further include the first inert gas supply system. 
     &lt;Reactive Gas Supply System&gt; 
     A reactive gas supply source  244   b,  an MFC  244   c  and a valve  244   d  are provided at the second gas supply pipe  244   a  in the sequential order from an upstream side to a downstream side of the second gas supply pipe  244   a.  The RPU  244   e  is provided downstream of the valve  244   d  provided at the second gas supply pipe  244   a.  The reactive gas is supplied into the shower head  230  via the second gas supply pipe  244   a  provided with the MFC  244   c  and the valve  244   d  and the common gas supply pipe  242 . The reactive gas is activated into a plasma state by the RPU  244   e  and then supplied (irradiated) onto the wafer  200 . 
     The reactive gas (second gas) is another of the process gases. For example, the reactive gas contains a second element (for example, nitrogen) different from the first element (for example, silicon) contained in the source gas. Specifically, for example, ammonia (NH 3 ) gas serving as a nitrogen (N)-containing gas may be used as the reactive gas. 
     The reactive gas supply system  244  is constituted mainly by the second gas supply pipe  244   a,  the MFC  244   c  and the valve  244   d.  The reactive gas supply system  244  may further include the reactive gas supply source  244   b,  the RPU  244   e  and a second inert gas supply system described later. In addition, since the reactive gas supply system  244  is configured to supply the reactive gas which is another of the process gases, the reactive gas supply system  244  is a part of the process gas supply system. 
     A downstream end of a second inert gas supply pipe  247   a  is connected to the second gas supply pipe  244   a  at a downstream side of the valve  244   d  provided at the second gas supply pipe  244   a.  An inert gas supply source  247   b,  an MFC  247   c  and a valve  247   d  are provided at the second inert gas supply pipe  247   a  in the sequential order from an upstream side to a downstream side of the second inert gas supply pipe  247   a.  The inert gas is supplied into the shower head  230  via the second inert gas supply pipe  247   a  provided with the MFC  247   c  and the valve  247   d,  the second gas supply pipe  244   a  and the RPU  244   e.    
     The inert gas acts as a carrier gas or a dilution gas of the reactive gas. Specifically, for example, the nitrogen (N 2 ) gas may be used as the inert gas. Instead of the N 2  gas, for example, a rare gas such as helium (He) gas, neon (Ne) gas and argon (Ar) gas may be used as the inert gas. 
     The second inert gas supply system is constituted mainly by the second inert gas supply pipe  247   a,  the MFC  247   c  and the valve  247   d.  The second inert gas supply system may further include the inert gas supply source  247   b,  the second gas supply pipe  244   a  and the RPU  244   e.  As described above, the reactive gas supply system  244  may further include the second inert gas supply system. 
     &lt;Purge Gas Supply System&gt; 
     A purge gas supply source  245   b,  an MFC  245   c  and a valve  245   d  are provided at the third gas supply pipe  245   a  in the sequential order from an upstream side to a downstream side of the third gas supply pipe  245   a.  When processing the wafer  200  according to a substrate processing described later, the inert gas serving as the purge gas is supplied into the shower head  230  via the third gas supply pipe  245   a  provided with the MFC  245   c  and the valve  245   d  and the common gas supply pipe  242 . When cleaning the shower head  230  or the process chamber  201  according to a process space cleaning step described later, the inert gas serving as a carrier gas or a dilution gas of the cleaning gas is supplied into the shower head  230  via the MFC  245   c,  the valve  245   d  and the common gas supply pipe  242  as necessary. 
     The inert gas supplied from the purge gas supply source  245   b  acts as the purge gas of purging the gas remaining in the process vessel  202  or in the shower head  230  in the substrate processing, and may act as the carrier gas or the dilution gas of the cleaning gas in the process space cleaning step. Specifically, for example, the nitrogen (N 2 ) gas may be used as the inert gas. Instead of the N 2  gas, for example, a rare gas such as helium (He) gas, neon (Ne) gas and argon (Ar) gas may be used as the inert gas. 
     The purge gas supply system  245  is constituted mainly by the third gas supply pipe  245   a,  the MFC  245   c  and the valve  245   d.  The purge gas supply system  245  may further include the purge gas supply source  245   b  and a process space cleaning gas supply system  248  described later. 
     &lt;Process Space Cleaning Gas Supply System&gt; 
     A downstream end of a process space cleaning gas supply pipe  248   a  is connected to the third gas supply pipe  245   a  at a downstream side of the valve  245   d  provided at the third gas supply pipe  245   a.  A process space cleaning gas supply source  248   b,  an MFC  248   c  and a valve  248   d  are provided at the process space cleaning gas supply pipe  248   a  in the sequential order from an upstream side to a downstream side of the process space cleaning gas supply pipe  248   a.  In the process space cleaning step, the cleaning gas is supplied into the shower head  230  via the process space cleaning gas supply pipe  248   a  provided with the MFC  248   c  and the valve  248   d,  the third gas supply pipe  245   a  and the common gas supply pipe  242 . 
     In the process space cleaning step, the cleaning gas (fourth gas) supplied from the process space cleaning gas supply source  248   b  acts as a cleaning gas of removing substances such as by-products (also referred to as “reaction by-products”) attached to the shower head  230  and the process vessel  202 . Specifically, for example, nitrogen trifluoride (NF 3 ) gas may be used as the cleaning gas. In addition, for example, a gas such as hydrogen fluoride (HF) gas, chlorine trifluoride (ClF 3 ) gas and fluorine (F 2 ) gas or a combination thereof may be used as the cleaning gas. 
     The process space cleaning gas supply system  248  is constituted mainly by the process space cleaning gas supply pipe  248   a,  the MFC  248   c  and the valve  248   d.  The process space cleaning gas supply system  248  may further include the process space cleaning gas supply source  248   b  and the third gas supply pipe  245   a.  In addition, the purge gas supply system  245  may further include the process space cleaning gas supply system  248 . 
     While the first embodiment is described by way of an example in which each of the source gas supply system  243 , the reactive gas supply system  244 , the purge gas supply system  245  and the process space cleaning gas supply system  248  are connected to the process chamber  201  via the common gas supply pipe (first supply pipe)  242 , the first embodiment is not limited thereto. For example, the gas supply pipes of the source gas supply system  243 , the reactive gas supply system  244 , the purge gas supply system  245  and the process space cleaning gas supply system  248  may be directly connected to components such as the shower head  230  and the process chamber  201 . 
     In addition, each of the source gas supply system  243 , the reactive gas supply system  244 , the purge gas supply system  245  and the process space cleaning gas supply system  248  or a combination thereof may also be referred to as a “process chamber gas supply system”. Then, the process chamber gas supply system functions as a system that supplies the process gas, the purge gas or the cleaning gas to the components such as the shower head  230  and the process chamber  201 . 
     &lt;Gas Exhaust System&gt; 
     The exhaust pipe  222  is connected to an inside of the exhaust buffer chamber  209  via an exhaust port  221  provided on an upper surface or a side surface of the exhaust buffer chamber  209 . Thus, the exhaust pipe  222  communicates with an inside of the process chamber  201  via the exhaust port  221  and the exhaust buffer chamber  209 . 
     An APC (Automatic Pressure Controller) valve  223  serving as a pressure controller is provided at the exhaust pipe  222 . The APC valve  223  is configured to adjust (control) an inner pressure of the process chamber  201  communicating with the exhaust buffer chamber  209  to a predetermined pressure. The APC valve  223  includes a valve body (not shown) capable of adjusting the opening degree thereof. The APC valve  223  is configured to adjust a conductance of the exhaust pipe  222  in accordance with an instruction from a controller  260  described later. Hereinafter, the APC valve  223  provided at the exhaust pipe  222  may be simply referred to as the valve  223 . 
     A vacuum pump  224  is provided at the exhaust pipe  222  at a downstream side of the APC valve  223 . The vacuum pump  224  is configured to exhaust an inner atmosphere of the exhaust buffer chamber  209  and an inner atmosphere of the process chamber  201  communicating with the exhaust buffer chamber  209  via the exhaust pipe  222 . Thus, the exhaust pipe  222  functions as an exhaust pipe configured to exhaust the gas from the process chamber  201 . 
     A gas exhaust system is constituted mainly by the exhaust pipe  222 , the APC valve  223  and the vacuum pump  224 . 
     &lt;Exhaust Pipe Cleaning Contribution Gas Supply System&gt; 
     Separately from the process space cleaning gas supply system  248 , the exhaust pipe cleaning contribution gas supply system (hereinafter, also simply referred to as “exhaust pipe gas supply system”)  249  serving as a part of the gas supply system is connected to the exhaust pipe  222  constituting the gas exhaust system. 
     The exhaust pipe gas supply system  249  includes an exhaust pipe cleaning contribution gas supply pipe (hereinafter, also simply referred to as an “exhaust pipe gas supply pipe”)  249   a  directly communicating with the exhaust pipe  222 . The exhaust pipe gas supply pipe  249   a  is provided separately from the common gas supply pipe (first supply pipe)  242 . Therefore, hereinafter, the exhaust pipe gas supply pipe  249   a  may also be referred to as a “second supply pipe”. 
     The exhaust pipe gas supply pipe (second supply pipe)  249   a  is connected to a predetermined deposition risky portion  222   a  in the exhaust pipe  222 . In the present specification, the term “deposition risky portion” refers to a portion where unwanted reactants (also referred to as “unnecessary reactants”) such as the by-products are likely to be deposited. According to the first embodiment, the deposition risky portion  222   a  is located in the exhaust pipe  222  between the exhaust port  221  and the APC valve  223 . That is, according to the first embodiment, the deposition risky portion  222   a  is determined such that a connection location of the exhaust pipe gas supply pipe  249   a  connected to the exhaust pipe  222  is located between the exhaust port  221  and the APC valve  223 . As described above, the exhaust pipe  222  is configured to communicate with the inside of the process chamber  201  via the exhaust port  221 , and the APC valve  223  is provided at the exhaust pipe  222 . Therefore, the deposition risky portion  222   a  may be located between the process chamber  201  and the APC valve  223 . 
     An exhaust pipe cleaning contribution gas supply source (hereinafter, also simply referred to as an “exhaust pipe gas supply source”)  249   b,  an WC  249   c  and a valve  249   d  are provided at the exhaust pipe gas supply pipe  249   a  in the sequential order from an upstream side to a downstream side of the exhaust pipe gas supply pipe  249   a.  The cleaning contribution gas is supplied into the exhaust pipe  222  via the exhaust pipe gas supply pipe  249   a  provided with the MFC  249   c  and the valve  249   d.    
     In the present specification, the term “cleaning contribution gas” refers to a gas contributing to a cleaning process of removing the substances such as the by-products attached to the exhaust pipe  222 . Specifically, for example, a cleaning gas of removing the substances such as the by-products or a cleaning auxiliary gas of activating the cleaning gas may be referred to as the cleaning contribution gas described herein. According to the first embodiment, the cleaning gas may be used as the cleaning contribution gas. For example, a fluorine-containing gas such as NF 3  gas, F 2  gas, HF gas and ClF 3  gas may be used as the cleaning gas (that is, the cleaning contribution gas). 
     The exhaust pipe gas supply system  249  is constituted mainly by the exhaust pipe gas supply pipe  249   a,  the MFC  249   c  and the valve  249   d.  The exhaust pipe gas supply system  249  may further include the exhaust pipe gas supply source  249   b.    
     &lt;Controller&gt; 
     The substrate processing apparatus  100  includes the controller  260  configured to control operations of the components of the substrate processing apparatus  100 . The controller  260  includes at least an arithmetic unit  261  and a memory device  262 . The controller  260  is connected to the components of the substrate processing apparatus  100  described above, calls a program or a recipe from the memory device  262  in accordance with an instruction from a host controller or a user, and controls the operations of the components of the substrate processing apparatus  100  according to the contents of the instruction. Specifically, the controller  260  may be configured to control the operations of the components such as the gate valve  205 , the elevating mechanism  218 , the heater  213 , the MFCs  243   c  through  248   c,  the valves  243   d  through  248   d,  the MFC  249   c,  the valve  249   d,  the APC valve  223  and the vacuum pump  224 . That is, control targets of the controller  260  may include at least a gas supply through the process chamber gas supply system and a gas supply through the exhaust pipe gas supply system  249 . 
     The controller  260  may be embodied by a dedicated computer or by a general-purpose computer. For example, the controller  260  may be embodied by preparing an external memory device storing the program described above and by installing the program onto the general-purpose computer using the external memory device. For example, the external memory device may include a magnetic tape, a magnetic disk such as a flexible disk and a hard disk, an optical disk such as a CD and a DVD, a magneto-optical disk such as an MO and a semiconductor memory such as a USB memory and a memory card. 
     The means for providing the program to the computer is not limited to the external memory device. For example, the program may be supplied to the computer (general-purpose computer) using communication means such as the Internet and a dedicated line. In addition, the memory device  262  or the external memory device may be embodied by a non-transitory computer readable recording medium. Hereafter, the memory device  262  and the external memory device may be collectively referred to as the recording medium. In the present specification, the term “recording medium” may refer to only the memory device  262 , may refer to only the external memory device or may refer to both of the memory device  262  and the external memory device. 
     (2) Substrate Processing 
     Subsequently, the substrate processing of processing the wafer  200 , which is a part of the manufacturing processes of the semiconductor device, will be described. The substrate processing is performed by using the above-described substrate processing apparatus  100 . Hereinafter, the substrate processing will be described by way of an example in which a film is formed on the wafer  200 . In particular, the substrate processing of the first embodiment will be described by way of an example in which a silicon nitride film (also simply referred to as an “SiN film”) serving as a silicon-containing film is formed on the wafer  200  by alternately supplying the DCS gas and the NH 3  gas onto the wafer  200 . That is, the DCS gas is used as the source gas (first gas), and the NH 3  gas is used as the reactive gas (second gas). In the following descriptions, in the substrate processing, the operations of the components of the substrate processing apparatus  100  are controlled by the controller  260 . 
       FIG. 2  is a flowchart schematically illustrating the substrate processing according to the first embodiment.  FIG. 3  is a flowchart schematically illustrating a film-forming step of the substrate processing shown in  FIG. 2 . 
     &lt;Substrate Loading and Heating Step S 102 &gt; 
     When the substrate processing is performed by using the substrate processing apparatus  100 , first, as shown in  FIG. 2 , a substrate loading and heating step S 102  is performed. In the substrate loading and heating step S 102 , the wafer  200  is transferred (loaded) into the process vessel  202 . After the wafer  200  is loaded into the process vessel  202 , a vacuum transfer robot (not shown) is retracted to an outside of the process vessel  202 , and the gate valve  205  is closed to seal the process vessel  202  hermetically. Thereafter, by elevating the substrate support table  212 , the wafer  200  is placed on the substrate placing surface  211  of the substrate support table  212 . By further elevating the substrate support table  212 , the wafer  200  is elevated to the position for processing the wafer  200  (that is, the wafer processing position) in the process chamber  201 . 
     After the wafer  200  is loaded into the transfer chamber  203  and elevated to the wafer processing position in the process chamber  201 , by operating (opening) the APC valve  223 , the exhaust buffer chamber  209  communicates with the vacuum pump  224  via the APC valve  223 . The APC valve  223  controls an exhaust flow rate of the exhaust buffer chamber  209  by the vacuum pump  224  by adjusting the conductance of the exhaust pipe  222 . The inner pressure of the process chamber  201  communicating with the exhaust buffer chamber  209  is thereby maintained at a predetermined processing pressure. 
     When the wafer  200  is placed on the substrate support table  212 , the electric power is supplied to the heater  213  embedded in the substrate support table  212  such that a temperature (surface temperature) of the wafer  200  is adjusted to a predetermined processing temperature. In the substrate loading and heating step S 102 , a temperature of the heater  213  is adjusted by controlling a state of electric conduction to the heater  213  based on temperature information detected by a temperature sensor (not shown). 
     In the substrate loading and heating step S 102 , the inner pressure of the process chamber  201  is adjusted to the predetermined processing pressure and the surface temperature of the wafer  200  is adjusted to the predetermined processing temperature. In the present specification, the predetermined processing temperature and the predetermined processing pressure refer to a processing temperature and a processing pressure, respectively, at which the SiN film can be formed by alternately supplying the DCS gas and the NH 3  gas onto the wafer  200  in a film-forming step S 104  described later. That is, the predetermined processing temperature and the predetermined processing pressure refer to the processing temperature and the processing pressure, respectively, at which the source gas supplied in a first process gas supply step (also be referred to as a “source gas supply step”) S 202  described later cannot be self-decomposed. Specifically, for example, the processing temperature may range from the room temperature to 500° C., preferably from the room temperature to 400° C. For example, the processing pressure may range from 50 Pa to 5,000 Pa. The processing temperature and the processing pressure are also maintained in the film-forming step S 104  described later. 
     &lt;Film-Forming Step S 104 &gt; 
     After the substrate loading and heating step S 102 , the film-forming step S 104  is performed. Hereinafter, the film-forming step S 104  will be described in detail with reference to 
       FIG. 3 . As the film-forming step S 104 , a cyclic process may be performed by repeating alternately supplying different process gases (that is, by repeatedly and alternately performing the first process gas supply step S 202  and a second process gas supply step S 206  described later). 
     &lt;First Process Gas Supply Step S 202 &gt; 
     In the film-forming step S 104 , first, the first process gas supply step (source gas supply step) S 202  is performed. In the first process gas supply step S 202 , the DCS gas serving as the source gas (first gas) is supplied into the process chamber  201  through the source gas supply system  243 . The DCS gas supplied into the process chamber  201  is then supplied onto a surface of the wafer  200  at the wafer processing position. By the DCS gas contacting the surface of the wafer  200 , a silicon-containing layer serving as a first element-containing layer is formed on the surface of the wafer  200 . For example, the silicon-containing layer having a predetermined thickness and a predetermined distribution is formed according to the conditions such as an inner pressure of the process vessel  202  (that is, the inner pressure of the process chamber  201 ), a flow rate of the DCS gas supplied into the process chamber  201 , a temperature of the substrate support table  212  and the time taken for the DCS gas to pass through the process chamber  201 . 
     After a predetermined time elapses from the supply of the DCS gas, the valve  243   d  is closed to stop the supply of the DCS gas. In the first process gas supply step S 202 , the inner pressure of the process chamber  201  is controlled (adjusted) by the APC valve  223  to the predetermined processing pressure. 
     &lt;Purge Step S 204 &gt; 
     After the first process gas supply step S 202 , a purge step S 204  is performed. In the purge step S 204 , the N 2  gas is supplied through the purge gas supply system  245  to purge the process chamber  201  and the shower head  230 . As a result, the DCS gas that could not be bonded to the wafer  200  in the first process gas supply step S 202  is removed from the process chamber  201  by the vacuum pump  224 . 
     &lt;Second Process Gas Supply Step S 206 &gt; 
     After the purge step S 204 , the NH 3  gas serving as the reactive gas (second gas) is supplied into the process chamber  201  through the reactive gas supply system  244 . The NH 3  gas may be activated into the plasma state by the RPU  244   e  and then irradiated onto the surface of the wafer  200  at the wafer processing position. By supplying the NH 3  gas into the process chamber  201 , the silicon-containing layer formed on the surface of the wafer  200  is modified (changed) to form, for example, the SiN film which is a layer containing silicon (Si) and nitrogen (O). 
     After a predetermined time elapses from the supply of the NH 3  gas, the valve  244   d  is closed to stop the supply of the NH 3  gas. Similar to the first process gas supply step S 202 , the inner pressure of the process chamber  201  in the second process gas supply step S 206  is controlled (adjusted) by the APC valve  223  to the predetermined processing pressure. 
     &lt;Purge Step S 208 &gt; 
     After the second process gas supply step S 206 , a purge step S 208  is performed. The operations of the components of the substrate processing apparatus  100  in the purge step S 208  is similar to those of the components in the purge step S 204 . Therefore, the detailed descriptions of the purge step S 208  are omitted. 
     &lt;Determination Step S 210 &gt; 
     Hereinafter, a determination step S 210  will be described. After the purge step S 208  is completed, in the determination step S 210 , the controller  260  determines whether a cycle including the first process gas supply step S 202  through the purge step S 208  has been performed a predetermined number of times (n times). When the controller  260  determines, in the determination step S 210 , that the cycle has not been performed the predetermined number of times (n times) (“NO” in  FIG. 3 ), the first process gas supply step S 202  through the purge step S 208  are performed again. When the controller  260  determines, in the determination step S 210 , that the cycle has been performed the predetermined number of times (n times) (“YES” in  FIG. 3 ), the film-forming step S 104  is terminated. 
     As described above, in the film-forming step S 104 , by sequentially performing the first process gas supply step S 202  through the purge step S 208 , the SiN film having a predetermined thickness is deposited on the surface of the wafer  200 . By performing the cycle including the first process gas supply step S 202  through the purge step S 208  a predetermined number of times, it is possible to control the thickness of the SiN film formed on the surface of the wafer  200  to a desired thickness. 
     &lt;Substrate Unloading Step S 106 &gt; 
     After the film-forming step  5104  is completed, as shown in  FIG. 2 , a substrate unloading step  5106  is performed by the substrate processing apparatus  100 . In the substrate unloading step S 106 , the processed wafer  200  is transferred (unloaded) out of the process vessel  202  in the order reverse to that of the substrate loading and heating step  5102 . Subsequent to a determination step S 108  described later, an unprocessed wafer  200  may be loaded into the process vessel  202  in the order same as that of the substrate loading and heating step  5102 . The loaded wafer  200  will be subject to the film-forming step S 104  thereafter. 
     &lt;Determination Step S 108 &gt; 
     After the substrate unloading step  5106  is completed, in the determination step  5108 , the controller  260  of the substrate processing apparatus  100  determines whether a cycle including the substrate loading and heating step  5102 , the film-forming step  5104  and the substrate unloading step S 106  has been performed a predetermined number of times. That is, the controller  260  determines whether the number of wafers including the wafer  200  processed in the film-forming step S 104  is equal to the predetermined number. When it is determined, in the determination step S 108 , that the cycle has not been performed the predetermined number of times (“NO” in  FIG. 2 ), the substrate loading and heating step S 102 , the film-forming step S 104  and the substrate unloading  5106  are performed again to process the unprocessed wafer  200 . When it is determined, in the determination step S 108 , that the cycle has been performed the predetermined number of times (“YES” in  FIG. 2 ), the substrate processing is terminated. 
     When the substrate processing is completed, no wafer remains in the process vessel  202 . 
     (3) Cleaning Step of Process Chamber 
     Subsequently, a cleaning step (also referred to as the “process space cleaning step”) of performing a cleaning process to the inside of the process chamber  201  of the substrate processing apparatus  100 , which is a part of the manufacturing processes of the semiconductor device, will be described. 
     When the substrate processing described above is repeatedly performed, the unnecessary reactants such as the by-products may be attached to a surface of a wall in the process vessel  202  (particularly, in the process chamber  201 ). Therefore, the substrate processing apparatus  100  performs the cleaning step of the process chamber  201  (that is, the process space cleaning step) at a predetermined timing (for example, after performing the substrate processing a predetermined number of times, after processing a predetermined number of wafers including the wafer  200  or after a predetermined time has elapsed from the previous cleaning process). 
     In the cleaning step of the process chamber  201 , the valve  248   d  is opened while the valves  243   d,    244   d,    245   d,    246   d,    247   d  and  249   d  are closed. Thereby, the cleaning gas is supplied into the process chamber  201  from the process space cleaning gas supply source  248   b  of the process space cleaning gas supply system  248  via the third gas supply pipe  245   a  and the common gas supply pipe  242 . Then, the cleaning gas supplied into the process chamber  201  removes attached substances such as the reaction by-products in the buffer space  232  and in the process chamber  201 . 
     As a result, for example, even when the substances such as the by-products attached to the surface of the wall in the process chamber  201 , it is possible to remove the substances such as the by-products by performing the cleaning step of the process chamber  201  at the predetermined timing. 
     (4) Cleaning Step of Exhaust Pipe 
     Subsequently, a cleaning step (also referred to as the “exhaust pipe cleaning step”) of performing a cleaning process to an inside of the exhaust pipe  222  of the substrate processing apparatus  100 , which is a part of the manufacturing processes of the semiconductor device, will be described. 
     When the substrate processing described above is repeatedly performed, the unnecessary reactants such as the by-products may be attached to not only the inside of the process chamber  201  but also the inside of the exhaust pipe  222  configured to exhaust the gas from the process chamber  201 . In particular, the unnecessary reactants such as the by-products may easily be attached to and be deposited on the deposition risky portion  222   a  of the exhaust pipe  222 . As described above, the deposition risky portion  222   a  is located between the exhaust port  221  and the APC valve  223 . Hereinafter, the reason will be briefly described. 
     The APC valve  223  is configured to adjust a pressure such as the inner pressure of the process chamber  201  and an inner pressure of the exhaust pipe  222  (particularly, a pressure of a portion between the exhaust port  221  and the APC valve  223  in the exhaust pipe  222 ). For example, the APC valve  223  adjusts the inner pressure of the process chamber  201  to the predetermined processing pressure when the substrate processing is performed. The heater  213  heats the inside of process chamber  201  to the predetermined processing temperature when the substrate processing is performed. Since an O-ring (not shown) having a low heat resistance is disposed as a sealing part between the exhaust pipe  222  and the process vessel  202 , the exhaust pipe  222  is configured not to be affected by the heat from the heater  213 . In addition, when the substrate processing is performed, the inner pressure of the exhaust pipe  222  becomes high because the gas flows from the process chamber  201 , which is wider, into the pipe (that is, the exhaust pipe  222 ), which is narrower. As described above, since the pressure is high and the temperature is low in the exhaust pipe  222 , particularly in a portion such as the deposition risky portion  222   a  between the exhaust port  221  and the APC valve  223 , the substances such as the by-products may easily be attached to and be deposited on the portion. 
     Therefore, according to the first embodiment, after the cleaning step of the process chamber  201  is performed, subsequently, the cleaning step of the exhaust pipe  222  is performed. 
     According to the cleaning step of the exhaust pipe  222 , after stopping the supply of the cleaning gas through the common gas supply pipe  242 , which has been performed in the cleaning step of the process chamber  201 , the supply of the purge gas through the common gas supply pipe  242  is started. More specifically, by closing the valve  248   d  and opening the valve  245   d,  the purge gas is supplied into the process chamber  201  from the purge gas supply source  245   b  through the third gas supply pipe  245   a  and the common gas supply pipe  242 . 
     Thereafter, in the cleaning step of the exhaust pipe  222 , the valve  249   d  is opened. Thereby, the cleaning gas serving as the cleaning contribution gas is supplied to the deposition risky portion  222   a  in the exhaust pipe  222  (that is, the portion between the exhaust port  221  and the APC valve  223 ) from the exhaust pipe gas supply source  249   b  through the exhaust pipe gas supply pipe  249   a.  That is, in parallel with supplying the purge gas through the common gas supply pipe  242  to the process chamber  201 , the cleaning gas is supplied to the deposition risky portion  222   a  in the exhaust pipe  222  through the exhaust pipe gas supply pipe  249   a.  As a result, the cleaning gas supplied to the deposition risky portion  222   a  removes the attached substances such as the reaction by-products at the deposition risky portion  222   a.    
     In the cleaning step of the exhaust pipe  222 , the purge gas is supplied into the process chamber  201 . Therefore, even when the cleaning gas is supplied directly into the exhaust pipe  222 , it is possible to suppress the cleaning gas from entering the process chamber  201 . That is, the purge gas supplied into the process chamber  201  prevents the cleaning gas supplied into the exhaust pipe  222  from entering the process chamber  201 . In addition, by supplying the purge gas into the process chamber  201  before starting the supply of the cleaning gas into the exhaust pipe  222 , it is possible to reliably prevent the cleaning gas from entering the process chamber  201 . 
     (5) Effects According to First Embodiment 
     According to the first embodiment described above, it is possible to provide one or more of the following effects. 
     (a) According to the first embodiment, the exhaust pipe gas supply pipe  249   a  is connected to the deposition risky portion  222   a  in the exhaust pipe  222 . Therefore, even when the substances such as the by-products are easily attached to and deposited on the deposition risky portion  222   a,  it is possible to remove the attached substances such as the reaction by-products at the deposition risky portion  222   a  by supplying the cleaning contribution gas to the deposition risky portion  222   a.    
     As described above, according to the first embodiment, it is possible to suppress the deposition of the reaction by-products not only in the process chamber  201  but also in the exhaust pipe  222 . Therefore, it is possible to suppress a decrease in a conductance of a gas flow due to the deposition of the reaction by-products in the exhaust pipe  222 . In addition, it is possible to prevent an increase in pressure gradient in the process chamber  201  due to the decrease in the conductance. As a result, it is possible to prevent a processing uniformity of the wafer  200  from deteriorating. 
     (b) According to the first embodiment, the deposition risky portion  222   a  in the exhaust pipe  222  is located between the exhaust port  221  and the APC valve  223 . As described above, the exhaust pipe  222  is configured to communicate with the inside of the process chamber  201  via the exhaust port  221 , and the APC valve  223  is provided at the exhaust pipe  222 . Since the pressure of the portion between the exhaust port  221  and the APC valve  223  is high and the temperature of the portion is low, the substances such as the by-products may easily be attached to and be deposited on the portion. Particularly, the exhaust pipe gas supply pipe  249   a  is connected to the portion where the reaction by-products are likely to be deposited. Therefore, it is possible to more effectively and efficiently suppress the deposition of the reaction by-products in the exhaust pipe  222 . 
     (c) According to the first embodiment, the cleaning gas serving as the cleaning contribution gas is supplied through the exhaust pipe gas supply system  249 . That is, the cleaning gas that directly contributes to the removal of the substances such as the by-products attached to the exhaust pipe  222  is supplied as the cleaning contribution gas. Therefore, by using the cleaning gas serving as the cleaning contribution gas, it is possible to more efficiently and reliably remove the substances such as the reaction by-products deposited on the exhaust pipe  222 . 
     (d) According to the first embodiment, when the gas is supplied through the exhaust pipe gas supply pipe  249   a  into the exhaust pipe  222 , the purge gas is supplied through the common gas supply pipe  242  into the process chamber  201 . Therefore, even when the cleaning gas is supplied directly into the exhaust pipe  222 , by supplying the purge gas, it is possible to suppress the cleaning gas from entering the process chamber  201 . In addition, by supplying the purge gas into the process chamber  201  before starting the supply of the cleaning gas into the exhaust pipe  222 , it is possible to reliably prevent the cleaning gas from entering the process chamber  201 . 
     Second Embodiment 
     Hereinafter, a second embodiment according to the technique of the present disclosure will be described in detail. In the second embodiment, only portions different from those of the first embodiment will be described in detail below, and the description of portions the same as the first embodiment will be omitted. 
     In the second embodiment, a configuration of the exhaust pipe gas supply system  249  and a cleaning step of the exhaust pipe  222  using the exhaust pipe gas supply system  249  according to the second embodiment are different from those of the first embodiment. 
     According to the second embodiment, the cleaning auxiliary gas serving as the cleaning contribution gas is supplied from the exhaust pipe gas supply source  249   b  of the exhaust pipe gas supply system  249 . When the fluorine-containing gas such as NF 3  gas and F 2  gas is supplied as the cleaning gas into the process chamber  201 , an oxygen-containing gas such as nitric oxide (NO) gas and oxygen (O 2 ) gas of activating the cleaning gas may be used as the cleaning auxiliary gas. In addition, the exhaust pipe gas supply system  249  may be configured to supply the cleaning gas in addition to the cleaning auxiliary gas. 
     Subsequently, the cleaning step of the exhaust pipe  222  using the exhaust pipe gas supply system  249  according to the second embodiment will be described. 
     In the cleaning step of the process chamber  201 , the cleaning gas is supplied into the process chamber  201  through the common gas supply pipe  242 . Then, the cleaning gas supplied into the process chamber  201  is exhausted out of the process vessel  202  through the exhaust buffer chamber  209  and the exhaust pipe  222 . 
     When the cleaning gas is exhausted through the exhaust buffer chamber  209  and the exhaust pipe  222 , the energy of the cleaning gas may be deactivated by the time it reaches the exhaust pipe  222 . In particular, since the inner pressure of the exhaust pipe  222  is higher than the inner pressure of the process chamber  201 , a kinetic efficiency of the cleaning gas is further reduced, and a cleaning effect by the cleaning gas is also reduced. 
     Therefore, according to the second embodiment, the cleaning step of the exhaust pipe  222  is performed in parallel with the cleaning step of the process chamber  201 . 
     In the cleaning step of the exhaust pipe  222 , by opening the valve  249   d,  the cleaning auxiliary gas serving as the cleaning contribution gas is supplied to the deposition risky portion  222   a  in the exhaust pipe  222  (that is, the portion between the exhaust port  221  and the APC valve  223 ) from the exhaust pipe gas supply source  249   b  through the exhaust pipe gas supply pipe  249   a.  That is, in parallel with supplying the cleaning gas through the common gas supply pipe  242  to the process chamber  201 , the cleaning auxiliary gas is supplied to the deposition risky portion  222   a  in the exhaust pipe  222  through the exhaust pipe gas supply pipe  249   a.    
     As a result, the cleaning gas, supplied through the common gas supply pipe  242  and having reached the deposition risky portion  222   a  in the exhaust pipe  222  via the process chamber  201 , is activated by the cleaning auxiliary gas supplied to the deposition risky portion  222   a.  Then, the cleaning gas activated by the cleaning auxiliary gas removes the attached substances such as the reaction by-products at the deposition risky portion  222   a  in the exhaust pipe  222  while an energy efficiency of the cleaning gas is increased and a cleaning ability of the cleaning gas in the exhaust pipe  222  is enhanced. 
     In the cleaning step of the exhaust pipe  222 , the cleaning gas, in addition to the cleaning auxiliary gas, may be simultaneously supplied through the exhaust pipe gas supply pipe  249   a.  When the cleaning gas is simultaneously supplied with the cleaning auxiliary gas through the exhaust pipe gas supply pipe  249   a,  a concentration of the cleaning gas is increased. As a result, it is possible to further enhance the cleaning ability of the cleaning gas in the exhaust pipe  222 . 
     According to the second embodiment described above, it is possible to provide one or more of the following effects in addition to the effects (a) through (d) of the first embodiment described above. 
     (e) According to the second embodiment, the cleaning auxiliary gas serving as the cleaning contribution gas is supplied through the exhaust pipe gas supply system  249  in parallel with supplying the cleaning gas through the common gas supply pipe  242  into the process chamber  201 . That is, by supplying the cleaning auxiliary gas, it is possible to activate the cleaning gas that has reached the deposition risky portion  222   a  in the exhaust pipe  222 . Therefore, the cleaning ability of the cleaning gas is enhanced by activating the cleaning gas. As a result, it is possible to more efficiently and reliably remove the substances such as the reaction by-products deposited on the exhaust pipe  222 . 
     (f) According to the second embodiment, the cleaning auxiliary gas is used as the cleaning contribution gas. Thus, it is possible to perform the cleaning step of the process chamber  201  in parallel with the cleaning step of the exhaust pipe  222 . Therefore, according to the second embodiment, it is possible to reduce the time required for the cleaning steps described above as compared with a case where each of the cleaning steps described above is performed separately. As a result, it is also possible to improve an operation rate of the substrate processing apparatus  100 . 
     Third Embodiment 
     Hereinafter, a third embodiment according to the technique of the present disclosure will be described. In the third embodiment, only portions different from those of the first embodiment or the second embodiment will be described in detail below, and the description of portions the same as the first embodiment or the second embodiment will be omitted. 
     In the third embodiment, a configuration of the exhaust pipe gas supply system  249  and a cleaning step of the exhaust pipe  222  using the exhaust pipe gas supply system  249  are different from those of the first embodiment.  FIG. 4  schematically illustrates a single-wafer type substrate processing apparatus (that is, a substrate processing apparatus  100   a ) according to the third embodiment. 
     As shown in  FIG. 4 , according to the substrate processing apparatus  100   a  of the third embodiment, the exhaust pipe gas supply system  249  further includes an exhaust pipe gas supply pipe (also referred to as a “third supply pipe”)  249   e  in addition to the exhaust pipe gas supply pipe  249   a,  the exhaust pipe gas supply source  249   b,  the MFC  249   c  and the valve  249   d  described in the first embodiment. The exhaust pipe gas supply pipe  249   e  directly communicates with the exhaust pipe  222 . An exhaust pipe gas supply source  249   f,  an MFC  249   g  and a valve  249   h  are provided at the exhaust pipe gas supply pipe  249   e  in the sequential order from an upstream side to a downstream side of the exhaust pipe gas supply pipe  249   e.  The cleaning contribution gas is supplied into the exhaust pipe  222  via the exhaust pipe gas supply pipe  249   e  provided with the MFC  249   g  and the valve  249   h.    
     The exhaust pipe gas supply pipe (third supply pipe)  249   e  is connected to a deposition risky portion  222   b  different from the deposition risky portion  222   a  of the exhaust pipe gas supply pipe  249   a.  The deposition risky portion  222   b  is located downstream of the APC valve  223  provided at the exhaust pipe  222 . More specifically, at the downstream side of the APC valve  223 , the deposition risky portion  222   b  is located immediately after the APC valve  223 . That is, according to the third embodiment, the deposition risky portion  222   b  is set such that a connection location of the exhaust pipe gas supply pipe  249   e  connected to the exhaust pipe  222  is located at the downstream of the APC valve  223  immediately after the APC valve  223 . In the present specification, the term “immediately after the APC valve  223 ” refers to a range of region where the APC valve  223  is not far away and a partial pressure and a temperature can be reduced as described later in detail. 
     Similar to the first embodiment, for example, the cleaning gas is used as the cleaning contribution gas supplied to the deposition risky portion  222   b  through the exhaust pipe gas supply pipe  249   e.  However, the third embodiment is not limited thereto. For example, similar to the second embodiment, the cleaning auxiliary gas may be used as the cleaning contribution gas. 
     Subsequently, the cleaning step of the exhaust pipe  222  performed using the exhaust pipe gas supply system  249  according to the third embodiment will be described. In the third embodiment, the cleaning step of the exhaust pipe  222  will be described by way of an example in which the cleaning gas is used as the cleaning contribution gas. 
     Similar to the first embodiment, after the cleaning step of the process chamber  201  is performed, the cleaning process of the cleaning step of the exhaust pipe  222  is performed by supplying the cleaning gas to the deposition risky portion  222   a  in the exhaust pipe  222  (that is, the portion between the exhaust port  221  and the APC valve  223 ) through the exhaust pipe gas supply pipe  249   e.    
     Thereafter, when the cleaning process for the deposition risky portion  222   a  is completed, the APC valve  223  is closed and the valve  249   h  is opened. Thereby, the cleaning gas serving as the cleaning contribution gas is supplied from the exhaust pipe gas supply source (also referred to as an “exhaust pipe cleaning contribution gas supply source”)  249   f  to the deposition risky portion  222   b  (that is, the portion immediately after the downstream side of the APC valve  223 ) of the exhaust pipe  222  different from the deposition risky portion  222   a.    
     By the influence of the vacuum pump  224 , the partial pressure and the temperature of the portion immediately after the APC valve  223  (that is, the range of the region described above) are reduced simultaneously. Therefore, the substances such as the by-products may easily be attached to and be deposited on the portion. 
     Therefore, according to the third embodiment, the range of the region described above is defined as the deposition risky portion  222   b.  By supplying the cleaning gas to the portion immediately after the downstream side of the APC valve  223 , it is possible to remove the attached substances such as the reaction by-products at the deposition risky portion  222   b.    
     While the third embodiment is described by way of an example in which the cleaning gas is supplied in order to remove the substances such as the by-products at the portion immediately after the downstream side of the APC valve  223 , the third embodiment is not limited thereto. For example, similar to the second embodiment, the cleaning auxiliary gas may be used. 
     While the third embodiment is described by way of an example in which the cleaning step of the exhaust pipe  222  includes the cleaning process of cleaning the deposition risky portion  222   a  (that is, the portion between the exhaust port  221  and the APC valve  223 ) and the cleaning process of cleaning the deposition risky portion  222   b  (that is, the portion immediately after the downstream side of the APC valve  223 ) performed after the cleaning process of cleaning the deposition risky portion  222   a,  the third embodiment is not limited thereto. For example, the cleaning step of the exhaust pipe  222  may include only the cleaning process of cleaning the portion immediately after the downstream side of the APC valve  223 . That is, in the exhaust pipe gas supply system  249 , only the exhaust pipe gas supply pipe  249   e  may be connected to the exhaust pipe  222 , and only the portion immediately after the downstream side of the APC valve  223  may be defined as the deposition risk location  222   b.    
     According to the third embodiment described above, it is possible to provide the following effect in addition to the effects (a) through (f) of the first embodiment or the second embodiment described above. 
     (g) According to the third embodiment, the deposition risky portion  222   b  of the exhaust pipe  222  is located downstream of the APC valve  223  provided at the exhaust pipe  222 . The partial pressure and the temperature of the portion downstream of the APC valve  223  (that is, the portion immediately after the APC valve  223 ) are reduced simultaneously. Particularly, the exhaust pipe gas supply pipe  249   e  is connected to the portion where the reaction by-products are likely to be deposited. Therefore, it is possible to more effectively and efficiently suppress the deposition of the reaction by-products in the exhaust pipe  222 . 
     Fourth Embodiment 
     Hereinafter, a fourth embodiment according to the technique of the present disclosure will be described. In the fourth embodiment, only portions different from those of the first embodiment or the second embodiment will be described in detail below, and the description of portions the same as the first embodiment or the second embodiment will be omitted. 
       FIG. 5  schematically illustrates a multi-wafer type substrate processing apparatus (that is, a substrate processing apparatus  100   b ) according to the fourth embodiment. 
     As shown in  FIG. 5 , a source gas supply region  201   a,  a purge gas supply region  201   b,  a reactive gas supply region  201   c  and a purge gas supply region  201   d  are arranged in the process chamber  201  of the substrate processing apparatus  100   b  of the fourth embodiment. The source gas (first gas), which is one of the process gases, is supplied to the source gas supply region  201   a.  The purge gas is supplied to the purge gas supply region  20  lb. The reactive gas, which is another of the process gases, is supplied to the reactive gas supply region  201   c.  The purge gas is also supplied to the purge gas supply region  201   d.  As the wafer  200  sequentially passes through the regions  201   a  to  201   d  by rotating a substrate support table on which wafers including the wafer  200  are placed, a film-forming process according to the fourth embodiment is performed onto the wafer  200 . 
     In the vicinity of the source gas supply region  201   a  in the process chamber  201 , a source gas exhaust pipe portion  222   c  is connected. The source gas exhausted from the process chamber  201  flows through the source gas exhaust pipe portion  222   c.  In the vicinity of the reactive gas supply region  201   c  in the process chamber  201 , a reactive gas exhaust pipe portion  222   d  is connected. The reactive gas exhausted from the process chamber  201  flows through the reactive gas exhaust pipe portion  222   d.  The source gas exhaust pipe portion  222   c  and the reactive gas exhaust pipe portion  222   d  join (merge) at a confluent portion (also referred to as a “junction”)  222   e  located downstream of each of the source gas exhaust pipe portion  222   c  and the reactive gas exhaust pipe portion  222   d.  That is, according to the substrate processing apparatus  100   b  of the fourth embodiment, the exhaust pipe  222  serving as an exhaust pipe configured to exhaust the gas from the process chamber  201  is constituted by: the source gas exhaust pipe portion  222   c  through which the source gas flows; the reactive gas exhaust pipe portion  222   d  through which the reactive gas flows; and the confluent portion  222   e  where the source gas exhaust pipe portion  222   c  and the reactive gas exhaust pipe portion  222   d  join. 
     The vacuum pump  224  is provided at the exhaust pipe  222  at a downstream side of the confluent portion  222   e  of the exhaust pipe  222 . The vacuum pump  224  is configured to exhaust the inner atmosphere (in particular, the source gas and the reactive gas) of the process chamber  201  via the exhaust pipe  222 . As described above, since the vacuum pump  224  is located downstream of the confluent portion  222   e,  even when exhausting the source gas and the reactive gas from the process chamber  201 , it is possible to exhaust the source gas and the reactive gas by using only the vacuum pump  224  without using separate pumps configured to exhaust the source gas and the reactive gas, respectively. 
     According to a configuration of the substrate processing apparatus  100   b,  the source gas and the reactive gas are simultaneously supplied to the process chamber  201 . Although exhaust ports corresponding to the source gas and the reactive gas are separately provided, the source gas exhaust pipe portion  222   c  and the reactive gas exhaust pipe portion  222   d  communicating with the exhaust ports, respectively, join at the confluent portion  222   e  provided downstream of each of the source gas exhaust pipe portion  222   c  and the reactive gas exhaust pipe portion  222   d.  Therefore, at the confluent portion  222   e,  the source gas and the reactive gas react with each other, whereby the substances such as the by-products may easily be attached to and be deposited on the confluent portion  222   e.  That is, according to the fourth embodiment, the confluent portion  222   e  may also be referred to as a “deposition risky portion  222   e ”. In addition, in order to avoid the deposition of the substances such as the by-products, the confluent portion  222   e  may not be provided. That is, the source gas and the reactive gas may be exhausted by using separate pumps configured to exhaust the source gas and the reactive gas, respectively. In this case, since a pump configured to exhaust the source gas and another pump configured to exhaust the reactive gas are required instead of the vacuum pump  224 , the configuration of the substrate processing apparatus  100   b  becomes complicated, and the cost of the substrate processing apparatus  100   b  increases. Therefore, it is not preferable to exhaust the source gas and the reactive gas in a separate manner. 
     Therefore, since according the substrate processing apparatus  100   b  of the fourth embodiment the confluent portion  222   e  is defined as the deposition risky portion  222   e  (that is, the deposition risky portion  222   e  is located at the confluent portion  222   e ), an exhaust pipe gas supply pipe (also referred to as a “fourth supply pipe”)  249   i  is connected to the confluent portion  222   e.  An exhaust pipe cleaning contribution gas supply source (also simply referred to as an “exhaust pipe gas supply source”)  249   j,  an WC  249   k  and a valve  249   l  are provided at the exhaust pipe gas supply pipe  249   i  in the sequential order from an upstream side to a downstream side of the exhaust pipe gas supply pipe  249   i.  The cleaning contribution gas is supplied into the exhaust pipe  222  via the exhaust pipe gas supply pipe  249   i  provided with the MFC  249   k  and the valve  249   l.    
     Similar to the first embodiment, for example, the cleaning gas is used as the cleaning contribution gas supplied to the confluent portion (deposition risky portion)  222   e  through the exhaust pipe gas supply pipe  249   i.  However, the fourth embodiment is not limited thereto. For example, similar to the second embodiment, the cleaning auxiliary gas may be used as the cleaning contribution gas. 
     Subsequently, the cleaning step of the exhaust pipe  222  performed by the substrate processing apparatus  100   b  of the fourth embodiment will be described. In the fourth embodiment, the cleaning step of the exhaust pipe  222  will be described by way of an example in which the cleaning gas is used as the cleaning contribution gas. 
     Similar to the first embodiment, according to the fourth embodiment, the cleaning step of the process chamber  201  is performed. After the cleaning step of the process chamber  201  is performed, the cleaning step of the exhaust pipe  222  according to the fourth embodiment is performed. 
     In the cleaning step of the exhaust pipe  222  according to the fourth embodiment, the valve  2491  is opened. Thereby, the cleaning gas serving as the cleaning contribution gas is supplied to the confluent portion (deposition risky portion)  222   e  in the exhaust pipe  222  from the exhaust pipe gas supply source  249   j  through the exhaust pipe gas supply pipe  249   i.  As a result, the cleaning gas supplied to the deposition risky portion  222   e  removes the attached substances such as the reaction by-products at the deposition risky portion  222   e.    
     While the fourth embodiment is described by way of an example in which the cleaning gas is supplied in order to remove the attached substances such as the by-products at the confluent portion (deposition risky portion)  222   e  in the exhaust pipe  222 , the fourth embodiment is not limited thereto. For example, similar to the second embodiment, the cleaning auxiliary gas may be used. 
     While the fourth embodiment is described by way of an example in which the cleaning step of the exhaust pipe  222  includes only a cleaning process of cleaning the deposition risky portion  222   e,  the fourth embodiment is not limited thereto. For example, the cleaning step of the exhaust pipe  222  may further include at least one among the cleaning process of cleaning the portion between the exhaust port  221  and the APC valve  223  and the cleaning process of cleaning the portion immediately after the downstream side of the APC valve  223 . 
     According to the fourth embodiment described above, it is possible to provide the following effect in addition to the effects (a) through (g) of the first embodiment, the second embodiment or the third embodiment described above. 
     (h) According to the fourth embodiment, the deposition risky portion  222   b  of the exhaust pipe  222  is located at the confluent portion  222   e  where the source gas exhaust pipe portion  222   c  and the reactive gas exhaust pipe portion  222   d  join. At the confluent portion  222   e,  the source gas and the reactive gas react with each other, whereby the substances such as the by-products may easily be attached to and be deposited on the confluent portion  222   e.  Particularly, the exhaust pipe gas supply pipe  249   i  is connected to the portion where the reaction by-products are likely to be deposited. Therefore, it is possible to more effectively and efficiently suppress the deposition of the reaction by-products in the exhaust pipe  222 . 
     Other Embodiments 
     While the technique is described in detail by way of the above-described embodiments, the above-described technique is not limited thereto. The above-described technique may be modified in various ways without departing from the gist thereof. 
     For example, in the first embodiment and the second embodiment, when the cleaning contribution gas is supplied to the deposition risky portion  222   a  in the exhaust pipe  222  (that is, the portion between the exhaust port  221  and the APC valve  223 ), the APC valve  223  may be fully closed so that the cleaning contribution gas is sealed in deposition risky portion  222   a.  By completely closing the APC valve  223 , the concentration of the cleaning gas at the deposition risky portion  222   a  increases. Therefore, it is possible to effectively improve a cleaning efficiency. 
     For example, the above-described embodiments are described by way of an example in which the SiN film is formed on the wafer  200  by alternately supplying the DCS gas serving as the source gas (first gas) and the NH 3  gas serving as the reactive gas (second gas). However, the above-described technique is not limited thereto. For example, the process gases used in the film-forming process are not limited to the DCS gas and the NH 3  gas. That is, the above-described technique may also be applied to film-forming processes wherein other gases are used to form different films, or three or more different process gases are alternately supplied to form a film. 
     For example, the second embodiment is described by way of an example in which the SiN film serving as a nitride film is formed on the wafer  200  by using the gas such as the NF 3  gas and the F 2  gas as the cleaning gas and using the gas such as the NO gas and the O 2  gas as the cleaning auxiliary gas. However, the above-described technique is not limited thereto. For example, when an oxide film such as a silicon oxide film (also referred to as an “SiO film”) is formed on the wafer  200 , hydrogen fluoride (HF) may be used as the cleaning gas and water vapor (H 2 O) or alcohol may be used as the cleaning auxiliary gas. When the HF and the H 2 O are supplied, the HF and the H 2 O may be supplied alternately (that is, the HF and the H 2 O are supplied using a cyclic supply process). When the HF and the H 2 O are mixed, the corrosiveness increases. Therefore, in order to prevent the HF and the H 2 O from mixing, the HF and the H 2 are separated by the cyclic supply process. 
     According to some embodiments in the present disclosure, it is possible to suppress the deposition of the reaction by-products in the exhaust pipe.