Patent Publication Number: US-2018051374-A1

Title: Film-forming apparatus, film-forming method, and storage medium

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2016-160147, filed on Aug. 17, 2016, the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a technique for sequentially supplying process gases which react with each other to a substrate so as to laminate reaction products on a surface of the substrate. 
     BACKGROUND 
     As one of techniques for forming a thin film such as a silicon nitride film on a semiconductor wafer (hereinafter, referred to as a “wafer”) which is a substrate, there is known an Atomic Layer Deposition (ALD) method in which a source gas and a reactant gas are sequentially supplied to the surface of the wafer to laminate reaction products. As a film-forming apparatus for performing a film-forming process using such an ALD method, for example, there is a configuration in which a rotary table for rotating a plurality of wafers arranged in the circumferential direction thereof is installed inside a vacuum vessel. 
     In such a film-forming apparatus, a gas nozzle is installed horizontally so as to extend in the radial direction of the rotary table, and a large number of gas discharge holes are arranged in the lower side of the gas nozzle in a region corresponding to a passage region of the wafer. Then, by discharging the gas downward from the gas discharge holes while rotating the rotary table, each of the source gas and the reactant gas is supplied to the entire surface of the wafer. For example, the source gas such as dichlorosilane (DCS) used for forming a silicon nitride film is adsorbed onto the wafer by chemical adsorption through the activation of the gas. 
     To do this, the wafer is heated via the rotary table by a heating part installed below the rotary table, so that the gas discharged from the gas nozzle is heated and activated. Here, specifically describing the activation of the gas, the gas discharged from the gas nozzle is heated by the heat radiated from the rotary table or the wafer while diffusing in the radial direction on the rotary table. At each position on the wafer, the gas is injected from above the respective position. Even if the gas is not yet sufficiently heated, another gas is injected to another position and flows into the respective position. Thus, another gas is also heated and activated while moving the rotary table or the wafer. 
     Thus, in a central region of the wafer, the gas discharged to a position far from the central region as seen in the radial direction of the rotary table travels a long distance and gets to the central region, so that the gas is activated during the period of time. That is to say, in the central region of the wafer, the gas remains sufficiently activated. On the other hand, at a peripheral portion of the wafer close to the central region of the rotary table, a distance between the peripheral portion of the wafer and an end portion of the gas nozzle is short. Thus, a movement distance at which the gas discharged from the end portion of the gas nozzle travels to the peripheral portion of the wafer is short. This holds true in a peripheral portion of the wafer close to an outer edge side of the rotary table. As a result, at the peripheral portions of the wafer in the radial direction of the rotary table, a film thickness tends to be lower than a film thickness of the central side of the wafer because the activation of the source gas is difficult to be performed sufficiently. 
     SUMMARY 
     Some embodiments of the present disclosure provide a technique for improving the in-plane uniformity of a film thickness by sequentially supplying process gases reacting with each other to a substrate to laminate reaction products on a surface of the substrate. 
     According to one embodiment of the present disclosure, there is provided a film-forming apparatus for forming a thin film on a substrate by performing, inside a vacuum vessel, a cycle of sequentially supplying a source gas and a reactant gas reacting with the source gas to generate a reaction product a plurality of times, the film-forming apparatus including: a rotary table installed inside the vacuum vessel, and including a substrate mounting region, on which the substrate is mounted, formed at one surface side of the rotary table, the rotary table being configured to rotate the substrate mounting region; a heating part configured to heat the substrate mounted on the rotary table; a first process region in which the source gas is supplied toward the substrate mounting region of the rotary table to perform a first process; a second process region defined apart from the first process region in a circumferential direction of the rotary table via a separation portion, and in which the reactant gas is supplied to perform a second process; and a main nozzle, a central-side auxiliary nozzle and a peripheral-side auxiliary nozzle installed in the first process region to extend in a direction intersecting with a movement path of the rotary table and along a rotational direction of the rotary table, each of the main nozzle, the central-side auxiliary nozzle and the peripheral-side auxiliary nozzle including gas discharge holes formed to discharge the source gas downward in a longitudinal direction thereof, wherein when a central side and a peripheral wall side of the vacuum vessel are respectively defined as an inner side and an outer side, respectively, the gas discharge holes of the main nozzle are formed to face an entire region of a passage region of the substrate when viewed in inward and outward directions and to face inner and outer regions of the passage region of the substrate on the rotary table, the gas discharge holes of the central-side auxiliary nozzle are formed in a region facing the inner region of the passage region of the substrate on the rotary table, the gas discharge holes of the peripheral-side auxiliary nozzle are installed in a region facing the outer region of the passage region of the substrate on the rotary table, and each of the central-side auxiliary nozzle and the peripheral-side auxiliary nozzle is installed to compensate for a shortage of the source gas supplied to an inner peripheral portion and an outer peripheral portion of the substrate from the main nozzle. 
     According to another embodiment of the present disclosure, there is provided a film-forming method for forming a thin film on a substrate by performing, inside a vacuum vessel, a cycle of sequentially supplying a source gas and a reactant gas reacting with the source gas to generate a reaction product a plurality of times, the film-forming method including: mounting the substrate on one surface side of a rotary table installed inside the vacuum vessel; heating the substrate; and repeatedly performing an operation of supplying and adsorbing the source gas to and onto the substrate by using gas nozzles, which are installed in a first process region and have gas discharge holes formed to discharge the source gas downward in a longitudinal direction, while rotating the substrate on the rotary table, and an operation of supplying, a plurality of times, the reactant gas to the substrate in a second process region separated from the first process region by a separation portion, wherein when a central side and a peripheral wall side of the vacuum vessel are respectively defined as an inner side and an outer side, respectively, in the first process region, an operation of supplying, by a main nozzle, the source gas to an entire region of a passage region of the substrate when viewed in inward and outward directions and each of an inner region and an outer region of the passage region of the substrate on the rotary table, an operation of supplying, by a central-side auxiliary nozzle, the source gas to an inner region of the passage region of the substrate on the rotary table, and an operation of supplying, by a peripheral-side auxiliary nozzle, the source gas to an outer region of the passage region of the substrate on the rotary table are performed. 
     According to yet another embodiment of the present disclosure, there is provided a non-transitory computer-readable storage medium storing a computer program that is used in a film-forming apparatus for forming a thin film on a substrate, by performing, inside a vacuum vessel, a cycle of sequentially supplying a source gas and a reactant gas reacting with the source gas to generate a reaction product a plurality of times, wherein the computer program incorporates a group of steps so as to execute the aforementioned film-forming method. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the present disclosure. 
         FIG. 1  is a longitudinal sectional view of a film-forming apparatus according to an embodiment of the present disclosure. 
         FIG. 2  is a plan view of the film-forming apparatus. 
         FIGS. 3A and 3B  are a perspective view and a cross-sectional view showing a first process region. 
         FIG. 4  is a plan view showing the first process region. 
         FIG. 5  is an explanatory view showing the activation of a DCS gas supplied in the first process region. 
         FIGS. 6A to 6C  are explanatory views showing an adsorption amount of a DCS gas supplied in the first process region. 
         FIG. 7  is a plan view showing another example of a film-forming apparatus according to an embodiment of the present disclosure. 
         FIG. 8  is a cross-sectional perspective view showing a modified example of a peripheral-side auxiliary nozzle. 
         FIG. 9  is a cross-sectional view showing a modified example of a peripheral-side auxiliary nozzle. 
         FIG. 10  is an explanatory view for explaining main nozzles in Experimental Examples 1-1 to 1-3. 
         FIG. 11  is a characteristic view showing a film thickness distribution of a wafer in an X-axis direction in Experimental Examples 1-1 to 1-3. 
         FIG. 12  is a characteristic view showing a film thickness distribution of a wafer in a Y-axis direction in Experimental Examples 1-1 to 1-3. 
         FIG. 13  is an explanatory view for explaining central-side auxiliary nozzles in Experimental Examples 2-1 to 2-3. 
         FIG. 14  is a characteristic view showing a film thickness distribution of a wafer in a Y-axis direction in Experimental Examples 2-1 to 2-3. 
         FIG. 15  is a characteristic view showing a film thickness distribution of a wafer in a Y-axis direction in Experimental Examples 2-4 to 2-7. 
         FIG. 16  is an explanatory view for explaining peripheral-side auxiliary nozzles in Experimental Examples 3-1 to 3-3. 
         FIG. 17  is a characteristic view showing a film thickness distribution of a wafer in a Y-axis direction in Experimental Examples 3-1 to 3-3. 
         FIG. 18  is a characteristic view showing a film thickness distribution of a wafer in a Y-axis direction in Experimental Examples 3-4 to 3-7. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to various embodiments, examples of which are illustrated in the accompanying drawings. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be apparent to one of ordinary skill in the art that the present disclosure may be practiced without these specific details. In other instances, well-known methods, procedures, systems, and components have not been described in detail so as not to unnecessarily obscure aspects of the various embodiments. 
     A film-forming apparatus according to an embodiment of the present disclosure will be described. As shown in  FIGS. 1 and 2 , the film-forming apparatus includes a vacuum vessel  1  having a substantially circular shape in a plan view, and a rotary table  2  installed in the vacuum vessel  1  and rotates a wafer W. The rotary table  2  has a rotational center at the center of the vacuum vessel  1 . The vacuum vessel  1  is provided with a ceiling plate  11  and a container body  12 . The ceiling plate  11  can be attached to and detached from the container body  12 . A separation gas supply pipe  51  which supplies a nitrogen (N 2 ) gas as a separation gas is connected to a central portion at an upper surface side of the ceiling plate  11  so as to suppress different process gases from being mixed with each other at a central portion in the vacuum vessel  1 . 
     The rotary table  2  is fixed to a substantially cylindrical core portion  21  in a central region C. The rotary table  2  can be rotated around a vertical axis, in this embodiment, in the clockwise direction as viewed from above, by a rotary shaft  22  connected to a lower surface of the core portion  21  and extending in a vertical direction. In  FIG. 1 , reference numeral  23  denotes a driving part for rotating the rotary shaft  22  around the vertical axis, and reference numeral  20  denotes a case body for accommodating the rotary shaft  22  and the driving part  23 . A purge gas supply pipe  72  for supplying a N 2  gas as a purge gas to a region below the rotary table  2  is connected to the case body  20 . 
     As shown in  FIGS. 1 and 2 , a circular concave portion  24  in which a wafer W having a diameter of, for example, 300 mm is mounted, is formed as a substrate mounting region in a surface portion (upper surface portion) of the rotary table  2 . The concave portion  24  is formed at a plurality of (e.g., five) locations along a rotational direction (circumferential direction) of the rotary table  2 . The concave portion  24  has a diameter dimension and a depth dimension so that when the wafer W is accommodated in the concave portion  24 , a surface of the wafer W and a surface of the rotary table  2  (area where the wafer W is not mounted) are aligned. 
     Returning to  FIG. 1 , a heater unit  7  as a heating part is installed over the entire circumference in a space between the rotary table  2  and a bottom surface portion of the vacuum vessel  1 . The heater unit  7  heats the wafer W mounted on the rotary table  2  at, for example, 400 degrees C. via the rotary table  2 . In  FIG. 1 , reference numeral  71  denotes a cover member installed at a lateral side of the heater unit  7 , and reference numeral  70  denotes a cover member for covering an upper side of the heater unit  7 . In addition, a purge gas supply pipe  73  is installed to pass through the bottom surface portion of the vacuum vessel  1  at a plurality of locations below the heater unit  7  in the circumferential direction. 
     As shown in  FIG. 2 , a transfer port  15  through which the wafer W is transferred between an external transfer arm (not shown) and the rotary table  2 , is formed in a lateral wall of the vacuum vessel  1 . The transfer port  15  can be air-tightly opened and closed by a gate valve (not shown). The wafer W is transferred between the external transfer arm and the rotary table  2  at a transfer position facing the transfer port  15  in the concave portion  24  of the rotary table  2 . Transfer lifting pins and a lifting mechanism (both not shown) are installed at a location corresponding to the transfer position. The transfer lifting pins pass through the concave portion  24  from below the rotary table  2  to lift up the wafer W from a back surface thereof. 
     As shown in  FIG. 2 , at positions facing regions through which the concave portions  24  of the rotary table  2  pass, a modification region P 3 , a separation gas supply part  35 , a first process region P 1 , a separation gas supply part  34 , and a second process region P 2  are arranged in this order at intervals in the clockwise direction (rotational direction of the rotary table  2 ) as viewed from the transfer port  15  and in the circumferential direction (the rotational direction of the rotary table  2 ) of the vacuum vessel  1 . 
     The first process region P 1  will be described with reference to  FIGS. 2 to 4 . In addition, gas discharge holes  44  formed in each nozzle are formed in a lower surface of the respective nozzle. However, for the sake of convenience in description, the gas discharge holes  44  are shown to be formed in an upper surface of the nozzle in  FIG. 4 . A main nozzle  41 , a peripheral-side auxiliary nozzle  42 , and a central-side auxiliary nozzle  43  which respectively supply a DCS gas as the process gas, are sequentially installed in the first process region P 1  from an upstream side in the rotational direction. These nozzles are installed to extend horizontally while facing the substrate mounting region of the rotary table  2 . 
     The main nozzle  41 , which extends from an outer peripheral wall of the vacuum vessel  1  toward the central region C, is installed to stride over a passage region through which the wafer W passes when the rotary table  2  is rotated. The main nozzle  41  is formed in a cylindrical shape whose distal end is sealed. A plurality of gas discharge holes  44  is formed in a lower surface of the main nozzle  41 . The plurality of gas discharge holes  44  is aligned at equal intervals in the longitudinal direction in a range from a position of 26 mm, which is a distance from an outer peripheral edge of the passage region of the wafer W to an outer peripheral side of the rotary table  2 , to a position of 24 mm, which is a distance from an inner peripheral edge of the passage region of the wafer W to a rotational central side of the rotary table  2 . 
     The peripheral-side auxiliary nozzle  42  is installed at a position adjacent to the main nozzle  41  at the downstream side in the rotational direction of the rotary table  2 . The peripheral-side auxiliary nozzle  42  compensates for the supply of gas from the main nozzle  41  to a peripheral portion of the wafer W at an outer edge side of the rotary table  2 . The peripheral-side auxiliary nozzle  42  extends from the outer peripheral wall of the vacuum vessel  1  toward the central region C in a range outward of the passage region of the wafer W on the rotary table  2 . The peripheral-side auxiliary nozzle  42  is formed in a cylindrical shape whose distal end is sealed. A plurality of another gas discharge holes  44  is formed at equal intervals in a lower surface of the peripheral-side auxiliary nozzle  42  in the longitudinal direction. The plurality of another gas discharge holes  44  is formed over a length region from several millimeters to several tens of millimeters which faces an outer region of the rotary table  2  rather than the passage region of the wafer W on the rotary table  2 . 
     The central-side auxiliary nozzle  43  is installed at a position adjacent to the peripheral-side auxiliary nozzle  42  at the downstream side in the rotational direction of the rotary table  2 . The central-side auxiliary nozzle  43  compensates for the supply of gas from the main nozzle  41  to the peripheral portion of the wafer W at the side of the central region C of the rotary table  2 . The central-side auxiliary nozzle  43  is installed to extend from the outer peripheral wall of the vacuum vessel  1  toward the central region C and stride over the passage region of the wafer W on the rotary table  2 . The central-side auxiliary nozzle  43  is formed in a cylindrical shape whose distal end is sealed. A plurality of another gas discharge holes  44  is formed at equal intervals in a lower surface of the distal end side of the central-side auxiliary nozzle  43  in the longitudinal direction in a length region from several millimeters to several tens of millimeters which faces the central region of the vacuum vessel  1  rather than the inner peripheral edge of the passage region of the wafer W on the rotary table  2 . In addition,  FIG. 3A  is an exploded perspective view of the first process region P 1 , and  FIG. 3B  is a cross-sectional view of the first process region P 1 . In the first process region P 1 , there is installed a nozzle cover  6  having a hat shape in cross-section that covers the main nozzle  41 , the peripheral-side auxiliary nozzle  42 , and the central-side auxiliary nozzle  43  from above in the longitudinal direction. The nozzle cover  6  is made of, for example, quartz. A gap is formed between an upper surface of the nozzle cover  6  and the ceiling plate  11  so that a portion of the separation gas flowing out from the separation gas supply parts  34  and  35  does not enter below the nozzle cover  6 . 
     Base end sides of the main nozzle  41 , the peripheral-side auxiliary nozzle  42 , and the central-side auxiliary nozzle  43  are respectively connected to gas supply pipes  41   a  to  43   a  which pass through the vacuum vessel  1 , and subsequently, are connected to respective DCS gas supply sources  45  via respective valves V 41  to V 43 . In addition, each of the DCS gas supply sources  45  also supplies a mixed gas of DCS and N 2  gas as a carrier gas, but is referred to as a DCS gas supply source for the sake of convenience. In the figures, M 41  to M 43  are flow rate controllers. 
     An ammonia (NH 3 ) gas supply nozzle  32  configured similarly to the main nozzle  41  is installed in the second process region P 2 . A base end side of the NH 3  gas supply nozzle  32  is connected to a gas supply pipe  32   a  passing through the vacuum vessel  1  and subsequently, is connected to an NH 3  gas supply source  48  which supplies an NH 3  gas. A plasma generating part  81  for changing the NH 3  gas discharged from the NH 3  gas supply nozzle  32  into plasma is installed above the second process region P 2 . 
     As shown in  FIGS. 1 and 2 , the plasma generating part  81  is configured by winding antennas  83  made of, for example, a metal wire, in a coil shape, and housed in a housing  80  made of, for example, quartz or the like. Each of the antennas  83  is coupled to a high frequency power source  85  having a frequency of, for example, 13.56 MHz and an output power of, for example, 5,000 W, by a connection electrode  86  in which a matching device  84  is installed. In the figure, reference numeral  82  denotes a Faraday shield for shielding an electric field generated from a high frequency generating part, and reference numeral  87  denotes a slit for allowing the magnetic field generated from the high frequency generating part to reach the wafer W. Further, reference numeral  89  indicated between the Faraday shield  82  and the antenna  83  denotes an insulating plate. 
     A plasma process gas nozzle  33  configured similarly to the main nozzle  41  is installed in the modification region P 3 . A base end side of the plasma process gas nozzle  33  is connected to a gas supply pipe  33   a  passing through the vacuum vessel  1  and subsequently, is connected to a mixed gas supply source  46  which supplies a mixed gas of an argon (Ar) gas and a hydrogen (H 2 ) gas. The plasma generating part  81  for converting the Ar gas and the H 2  gas discharged from the plasma process gas nozzle  33  into plasma is installed above the modification region P 3 , similarly to the second process region P 2 . 
     Each of the two separation gas supply parts  34  and  35  are configured by a nozzle similarly to the main nozzle  41 . Base end sides of the separation gas supply parts  34  and  35  are respectively connected to gas supply pipes  34   a  and  35   a  which pass through the vacuum vessel  1  and subsequently, are connected to respective N 2  gas supply sources  47 . As shown in  FIG. 2 , a convex portion  4  having a substantially fan-like planar shape is formed above each of the separation gas supply parts  34  and  35 . Each of the separation gas supply parts  34  and  35  is accommodated in a groove  36  formed in the convex portion  4 . The N 2  gas discharged from the separation gas supply part  34  diffuses from the separation gas supply part  34  to both sides in the circumferential direction of the vacuum vessel  1 , so that a first separation region D 1  for separating the atmosphere of the first process region P 1  side from the atmosphere of the second process region P 2  side is defined. In addition, the N 2  gas discharged from the separation gas supply part  35  diffuses from the separation gas supply part  35  to both sides in the circumferential direction of the vacuum vessel  1 , so that a second separation region D 2  for separating the atmosphere of the modification region P 3  side and the atmosphere of the first process region P 1  side is defined. 
     Therefore, the separation gas supply part  35  is installed between the modification region P 3  and the first process region P 1  when viewed from the upstream side in the rotational direction of the rotary table  2 , and the separation gas supply part  34  is installed between the first process region P 1  and the second process region P 2  when viewed from the upstream side in the rotational direction of the rotary table  2 . Further, the separation gas supply part  35  is installed between the second process region P 2  and the first process region P 1  when viewed from the upstream side in the rotational direction of the rotary table  2 . 
     As shown in  FIGS. 1 and 2 , a side ring  100  as a cover body, which includes a gas flow pass  101  as a groove portion formed therein, is installed at a position slightly lower than the rotary table  2  in the outer peripheral side of the rotary table  2 . In an upper surface of the side ring  100 , exhaust ports  61  are respectively formed at three locations such as a downstream side of the first process region P 1 , a downstream side of the second process region P 2 , and a downstream side of the modification region P 3  so as to be spaced apart from each other in the circumferential direction. As shown in  FIG. 1 , these exhaust ports  61  are respectively coupled to, for example, a vacuum pump  64  as a vacuum exhaust mechanism through an exhaust pipe  63  in which a pressure adjusting part  65  such as a butterfly valve is installed. 
     In addition, the film-forming apparatus is provided with a controller  120  composed of a computer for controlling the entire operations of the apparatus. A program for performing a film-forming process to be described later is stored in a memory of the controller  120 . This program includes a group of steps so as to execute operations of the apparatus to be described later, and is installed by a storage medium such as a hard disk, a compact disk, a magneto-optical disk, a memory card, a flexible disk, or the like. 
     The operation of the above-described embodiment will be described. In addition, in the specification, for the sake of convenience in description, a direction from an outer wall of the vacuum vessel  1  to the central region C is referred to as an Y-axis direction, and a direction orthogonal to the Y-axis direction, that is to say, a direction in which the wafer W moves when the rotary table  2  is rotated is referred to as an X-axis direction. First, the gate valve is opened and, for example, five wafers W are transferred into the vacuum vessel  1  via the transfer port  15  by the transfer arm while the rotary table  2  is intermittently rotated. Subsequently, the five waters W are mounted on the rotary table  2  with an elevation operation of the above-described lifting pins (not shown). Subsequently, the gate valve is closed and the interior of the vacuum vessel  1  is evacuated by the vacuum pump  64  and the pressure adjusting part  65 . In addition, the wafers W are heated at, for example, 400 degrees C. by the heater unit  7  while the rotary table  2  is rotated in the clockwise direction at a rotational speed of, for example, 10 rpm. 
     Subsequently, a mixed gas having a flow rate of 1,500 sccm in which a DCS gas having a flow rate of, for example, 1,000 sccm and a N 2  gas serving as a carrier gas having a flow rate of 500 sccm are mixed, is supplied from the main nozzle  41  in the first process region P 1 . In addition, a DCS gas is supplied from the peripheral-side auxiliary nozzle  42  at a flow rate of, for example, 20 sccm, and a DCS gas is supplied from the central-side auxiliary nozzle  43  at a flow rate of, for example, 20 sccm. In addition, in the specification, the mixed gas of the DCS gas and the N 2  gas is also described as a DCS gas for the sake of convenience in description. However, in the description of the flow rate of the gas discharged from the nozzle, it is assumed that, unless specifically mentioned otherwise that the DCS gas is a mixed gas, only the DCS gas is supplied. 
     In addition, an NH 3  gas is discharged into the second process region P 2  at a flow rate of, for example, 100 sccm, and a mixed gas of the Ar gas and the H 2  gas is discharged from the modification region P 3  at a flow rate of, for example, 10,000 sccm. In addition, a separation gas is discharged from the separation gas supply part  34  at a flow rate of, for example, 5,000 sccm and a N 2  gas is discharged from the separation gas supply pipe  51  and the purge gas supply pipes  72  and  73  at a predetermined flow rate. Then, the interior of the vacuum vessel  1  is adjusted to have a pressure of, for example, 100 Pa, by the pressure adjusting part  65 . Further, in the plasma generating part  81 , the high-frequency electric power of, for example, 1,500 W, is supplied to each antenna  83 . As a result, the gases supplied below the plasma generating part  81  are respectively activated by virtue of the magnetic field passed through the slits  87 . Thus, plasma such as ions and radicals is generated. 
     Subsequently, the rotary table  2  is rotated at a rotation speed of, for example, 10 rpm. The following description will be primarily focused on a single wafer W. First, the wafer W enters the first process region P 1  and sequentially passes in front of the main nozzle  41 , the peripheral-side auxiliary nozzle  42 , and the central-side auxiliary nozzle  43 . Although the DCS gas discharged from the gas discharge holes  44  of the main nozzle  41  remains not sufficiently heated immediately after the discharge, the DCS gas rises in temperature by the heat radiated from the rotary table  2  or the wafer W while diffusing in the radial direction on the rotary table  2  and gets activated. This phenomenon occurs in the entire area below the main nozzle  41 . Active species which has an amount corresponding to the total amount of gas entering from another position and the sufficiently heated gas, exist at each position of the wafer W as viewed in the radial direction on the wafer W. That is to say, for a certain position on the wafer W, the degree of activation (the amount of the active species) at the respective position is influenced by an arrival path of the gas until the gas reaches the respective position. 
     Therefore, since the DCS gas discharged from the main nozzle  41  reaches a peripheral side of the wafer W when viewed in the radial direction of the rotary table  2 , the DCS gas in the central portion of the wafer W is sufficiently activated. On the other hand, for the DCS gas discharged to the central portion of the wafer W from the main nozzle  41 , it can be said that the arrival path of the DCS gas until the gas reaches the peripheral portion of the wafer W is long at the peripheral portion of the wafer W close to the central side of the rotary table  2 . However, an end portion of the arrangement region of the gas discharge holes  44  of the main nozzle  41 , which is located farthest from the peripheral portion of the wafer W in the vicinity of the central side of the rotary table  2 , is close to the peripheral portion of the wafer W. Thus, an arrival path along which the DCS gas discharged from the end portion of the arrangement region reaches the peripheral portion of the wafer W is shorter than an arrival path to the central side of the rotary table  2  from the end portion of the arrangement region. This may hold true in the peripheral portion of the wafer W close to the outer edge side of the rotary table  2 . As a result, focusing on only to the main nozzle  41 , the degree of activation of the DCS gas is smaller at the peripheral portion of the wafer W than that at the central portion of the wafer W. 
     On the other hand, an arrangement region of the gas discharge holes  44  of the central-side auxiliary nozzle  43  is formed above the rotary table  2  closer to the central region C than the wafer W. Thus, the gas discharged from the gas discharge holes  44  diffuses and reaches the peripheral portion of the wafer W. An arrival path through which the DCS gas discharged from the central-side auxiliary nozzle  43  reaches the peripheral portion of the wafer W is short and the degree of activation in the respective peripheral portion is not large, that is to say, an amount of the activated DCS gas is not large. This compensates for the shortage of the amount of the active species of the DCS gas at the peripheral portion of the wafer W with respect to the central portion thereof, which occurs when only the main nozzle  41  is used. 
     Similarly, the DCS gas discharged from the peripheral-side auxiliary nozzle  42  compensates for the shortage of the amount of the active species of DCS gas at the peripheral portion of the wafer W in the outer edge side of the rotary table  2 . In this way, in the first process region P 1 , the DCS gas is supplied to the wafer W in a state of being activated with the good uniformity in the radial direction (the Y-axis direction) of the rotary table  2 , and adsorbed onto the wafer W. 
       FIG. 5  schematically shows the distribution of the amount of the active species of the DCS gas discharged from the nozzles  43 ,  41  and  42  as widths of strip-shaped portions  91  to  93 . In  FIG. 5 , the strip-shaped portion  91  located at the central portion represents the distribution of the amount of active species of the DCS gas discharged from the main nozzle  41 , the strip-shaped portion  92  located at the outer edge side of the rotary table  2  represents the distribution of the amount of active species of the DCS gas discharged from the peripheral-side auxiliary nozzle  42 , and the strip-shaped portion  93  located at the central side of the rotary table  2  represents the distribution of the amount of active species of the DCS gas discharged from the central-side auxiliary nozzle  43 . 
     Therefore, when the wafer W passes through the three nozzles of the central-side auxiliary nozzle  43 , the peripheral-side auxiliary nozzle  42 , and the main nozzle  41 , the DCS gas supplied from each of the nozzles  41  to  43  is adsorbed onto the wafer W.  FIG. 6  schematically shows an adsorption amount of the DCS gas supplied from each of the central-side auxiliary nozzle  43 , the peripheral-side auxiliary nozzle  42 , and the main nozzle  41  in the wafer W. As shown in  FIG. 6B , the adsorption amount of the DCS gas supplied from the main nozzle  41  decreases both in a region of the rotational central side of the rotary table  2  and a region close to the outer edge side of the rotary table  2  in the wafer W. On the other hand, as shown in  FIG. 6A , a large amount of the DCS gas supplied from the central-side auxiliary nozzle  43  is adsorbed onto the wafer W at the rotational central side of the rotary table  2 . Further, as shown in  FIG. 6C , a large amount of the DCS gas supplied from the peripheral-side auxiliary nozzle  42  is adsorbed onto the wafer W in a region close to the outer edge of the rotary table  2 . Accordingly, as the wafer W passes through the three nozzles  41  to  43 , the adsorption amounts of the DCS gas supplied from the nozzles  41  to  43  are combined with each other on the wafer W so that the uniformity of the adsorption amount of the DCS gas in the Y-axis direction of the wafer W is improved. 
     Then, the wafer W onto which the DCS gas is adsorbed in the first process region P 1  enters the second process region P 2  with the rotation of the rotary table  2 . The DCS gas adsorbed onto the wafer W is nitrided by the plasma of the NH 3  gas so that one or more molecular layers of a silicon nitride film (SiN film) which is a thin film component are formed, thus generating reaction products. 
     Then, by further rotating the rotary table  2 , the wafer W enters into the modification region P 3  where the plasma collides with the surface of the wafer W, for example, impurities are released from the SiN film as HCl, organic gas, or the like, or elements in the SiN film are rearranged, so that densification (high density) of the SiN film is achieved. By continuing the rotation of the rotary table  2  in this manner, the adsorption of the DCS gas onto the surface of the wafer W, the nitridation of the components of the DCS gas adsorbed onto the surface of the wafer W, and the plasma modification of the reaction products are performed multiple times in this order, so that the reaction products are laminated to form a thin film. 
     According to the above-described embodiment, the film forming-apparatus for forming the SiN film on the wafer W by performing, multiple times, a cycle in which the wafer W rotated by the rotary table  2  is heated and the DCS gas and the NH 3  gas are sequentially supplied to the wafer W inside the vacuum vessel  1 , is configured as follows. Specifically, the main nozzle  41  that extends from a peripheral wall of the vacuum vessel  1  toward the center of the rotary table  2  and supplies the DCS gas to the wafer W in the radial direction is installed to supply the DCS gas to the wafer W. Further, the peripheral-side auxiliary nozzle  42  which supplies the DCS gas to a region defined at the outer peripheral side of the rotary table  2  rather than the passage region of the wafer W in the rotary table  2  is installed. The central-side auxiliary nozzle  43  which supplies supply the DCS gas to a region defined at the central side of the rotary table  2  rather than the passage region of the wafer W is installed. Therefore, as described in detail above, when the DCS gas is supplied from the main nozzle  41 , the degree of activation of the DCS gas decreases as viewed in the radial direction of the rotary table  2 . That is to say, the activated DCS gas is supplied to both ends of the wafer W where the adsorption amount of the DSC gas becomes insufficient. Therefore, the in-plane uniformity of a film thickness of the film formed on the wafer W is improved. 
     Further, the adsorption of the DCS gas onto the wafer W requires heating and activating the DCS gas. To do this, the peripheral-side auxiliary nozzle  42  and the central-side auxiliary nozzle  43  are installed such that the gas discharge holes  44  thereof are arranged spaced apart from the passage region of the wafer W. The DCS gas is heated while diffusing and moving from outside the wafer so that the adsorption amount of the DCS gas increases at the inner and outer circumferential sides of the rotary table  2  on the wafer W. 
     It was found by the inventors of the present disclosure that, focusing on the distribution of the adsorption amount of the DCS gas onto the surface of the wafer W in the Y-axis direction when the DCS gas is supplied from the main nozzle  41 , the adsorption amount of the DCS gas at the central side of the rotary table  2  was the smallest at the end portion of the central side of the rotary table  2 . 
     Therefore, the distribution of the adsorption amount of the DCS gas by the central-side auxiliary nozzle  43  in the Y-axis direction may be adjusted such that the adsorption amount of the DCS gas is maximized at the peripheral side of the wafer W in the central side of the rotary table  2 . 
     As shown in a verification test 2 to be described later, the gas discharge holes  44  are arranged at a position close to the central side of the rotary table  2  from the inner peripheral edge of the passage region of the wafer W such that the DCS gas is supplied from the gas discharge holes  44 . It is therefore possible to obtain a maximum value of the adsorption amount of the DCS gas at a position close to the central side of the rotary table  2  in the periphery of the wafer W in the distribution of the adsorption amount of the DCS gas along the Y-axis direction. In some embodiments, a range in which the gas discharge holes  44  are arranged may set to a range of about 8 to 26 mm from the inner peripheral edge of the passage region of the wafer W to the central side of the rotary table  2 . 
     In addition, as a flow velocity of the DCS gas discharged from the central-side auxiliary nozzle  43  becomes slower or a partial pressure of the DCS gas becomes higher (as a value (the flow rate of the DCS gas/the flow rate of the DCS gas+the flow rate of the carrier gas) becomes larger), the DCS gas tends to stay at a discharge position on the rotary table  2 . Accordingly, a period of time until the DCS gas diffuses to the wafer W becomes longer, so that the activity tends to increase to cause the DCS gas to be easily adsorbed onto the wafer W. Therefore, by forming the gas discharge holes  44  in the central-side auxiliary nozzle  43  over an extent covering from the inner peripheral edge of the passage region of the wafer W to the central side of the rotary table  2 , it is possible to maximize the adsorption amount of the DCS at a position close to the peripheral edge of the central side of the rotary table  2 . 
     Therefore, as shown in a verification test 2 to be described later, a flow velocity of the DCS gas supplied from the central-side auxiliary nozzle  43  may be set to 40 sccm or less, specifically, 10 to 30 sccm. Thus, the adsorption amount of the DCS gas by the central-side auxiliary nozzle  43  in the Y-axis direction may be distributed such that the adsorption amount of the DCS gas is maximized at a position close to the central side of the rotary table  2  in the peripheral edge of the wafer W. Thus, by compensating for the shortage of the DCS gas supplied from the main nozzle  41 , it is possible to equalize the adsorption amount of the DCS gas at the position close to the central side of the rotary table  2  in the peripheral edge of the wafer W. 
     Similarly, it was found that, in the distribution of the adsorption amount of the DCS gas onto the surface of the wafer W in the Y-axis direction, the adsorption amount of the DCS gas at a position close to the outer edge side of the rotary table  2  in the surface of the wafer W was the smallest at an end portion close to the outer edge side of the rotary table  2  in the wafer W. 
     As shown in a verification test 3 to be described later, the gas discharge holes  44  are formed in the peripheral-side auxiliary nozzle  42  over an extent covering from the outer peripheral edge of the passage region of the wafer W to the outer edge side of the rotary table  2 , thus supplying the DCS gas. Therefore, in the distribution of the adsorption amount of the DCS gas in the Y-axis direction, it is possible to obtain a maximum value of the adsorption amount of the DCS gas at a peripheral edge close to the outer edge side of the rotary table  2  in the wafer W. In some embodiments, a range in which the gas discharge holes  44  are formed may be a range of about 9 to 28 mm from the outer peripheral edge of the passage region of the wafer W to the outer edge side of the rotary table  2 . 
     In addition, even in the peripheral-side auxiliary nozzle  42 , as a flow velocity of the discharged gas becomes slower or a partial pressure of the gas becomes higher, the DCS gas tends to stay and tends to be adsorbed onto the wafer W, so that the maximum value of the adsorption amount of the DCS gas may be obtained at the peripheral edge close to the outer edge side of the rotary table  2  in the wafer W. To achieve the above, a flow rate of the DCS gas may be 40 sccm or less, specifically 10 to 30 sccm. 
     In addition, by adjusting a flow rate ratio of the DCS gas and the carrier gas discharged from the peripheral-side auxiliary nozzle  42  and the central-side auxiliary nozzle  43  as described above, the film thickness distribution of a film formed by a film-forming gas discharged from each of the peripheral-side auxiliary nozzle  42  and the central-side auxiliary nozzle  43  changes. In this regard, the concentration of the DCS gas supplied from the main nozzle  41 , the peripheral-side auxiliary nozzle  42 , and the central-side auxiliary nozzle  43  may be adjusted. For example, as shown in  FIG. 7 , the other end side of the gas supply pipe  41   a  whose one end is connected to the main nozzle  41  is branched. One branched end of the gas supply pipe  41   a  is coupled to the DCS gas supply source  45  via a valve V 411  and a flow rate adjuster M 411 . In addition, the other branched end of the gas supply pipe  41   a  is coupled to an N 2  gas supply source  47  via a valve V 412  and a flow rate adjuster M 412 . Similarly, a gas supply pipe  42   a  is connected to the peripheral-side auxiliary nozzle  42  at one end thereof. The other end of the gas supply pipe  42   a  is branched. The branched ends are connected to the DCS gas supply source  45  and the N 2  gas supply source  47 . A gas supply pipe  43   a  is connected to the central-side auxiliary nozzle  43  at one end thereof. The other end of the gas supply pipe  43   a  is branched. The branched ends are connected to the DCS gas supply source  45  and the N 2  gas supply source  47 . In addition, in  FIG. 7 , reference numerals V 421 , V 422 , V 431 , and V 432  denote valves, and reference numerals M 421 , M 422 , M 431 , and M 432  denote flow rate adjusters. 
     By configuring as the above and adjusting each of the flow rate adjusters M 411 , M 412 , M 421 , M 422 , M 431  and M 432 , and the valves V 411 , V 412 , V 421 , V 422 , V 431  and V 432 , it is possible to adjust the concentration of the DCS gas supplied from each of the main nozzle  41 , the peripheral-side auxiliary nozzle  42 , and the central-side auxiliary nozzle  43 . Accordingly, the film thickness distribution of the film formed by the gas supplied from the main nozzle  41 , the film thickness distribution of the film formed by the gas supplied from the peripheral-side auxiliary nozzle  42 , and the film thickness distribution of the film formed by the gas supplied from the central-side auxiliary nozzle  43  may be respectively changed. It is therefore possible to adjust the uniformity of the film thickness distribution of the film formed on the wafer W. 
     A modified example of the peripheral-side auxiliary nozzle  42  will be described. When the rotary table  2  is rotated, a region at a peripheral wall side of the vacuum vessel  1  has a faster movement speed than the central side. As such, the supplied gas is likely to be cooled and the activity tends to deteriorate. Accordingly, the region of the wafer W in the vicinity of the peripheral wall side of the vacuum vessel  1  is likely to be decreased in the adsorption amount. Thus, the DCS gas supplied from the peripheral-side auxiliary nozzle  42  may be supplied after increasing the activity thereof. 
     For example, as shown in  FIGS. 8 and 9 , the peripheral-side auxiliary nozzle  42  includes a rectangular flat gas chamber  46 . The gas chamber  46  is disposed to face the rotary table  2 . The gas supply pipe  47  for supplying the DCS gas is connected to an upper surface of the gas chamber  46  at an upstream-side peripheral portion of the rotary table  2  in the rotational direction. A plurality of gas discharge holes  48  is formed along the radial direction of the rotary table  2  in a lower surface of the gas chamber  46  at a downstream-side peripheral portion of the rotary table  2  in the rotational direction. A partition wall  49  is installed in the vicinity of the gas supply pipe  47  in the gas chamber  46 . A longitudinally-extended slit  50  is formed in the partition wall  49 . 
     In the case of using the peripheral-side auxiliary nozzle  42  configured as above, the DCS gas supplied from the gas supply pipe  47  into the gas chamber  46  is heated by the heater unit  7  until the DCS gas passes through the slit  50  and is then discharged from the gas discharge holes  48  inside the gas chamber  46 . Therefore, the DCS gas may be supplied to the wafer W with the DCS gas heated to increase the activity thereof. It is therefore possible to quickly adsorb the DCS gas onto the wafer W even in the region of the wafer W in the vicinity of the peripheral wall side of the vacuum vessel  1 . In addition, a heating part may be installed in, for example, the gas chamber  46  in the peripheral-side auxiliary nozzle  42 . Further, the central-side auxiliary nozzle  43  and the main nozzle  41  may employ the same structure as that of the peripheral-side auxiliary nozzle  42  shown in  FIGS. 8 and 9 . 
     As the film-forming apparatus of the present disclosure, for example, a silicon oxide film forming apparatus which uses BTBAS (bistertiarybutylaminosilane) as a source gas and supplies an oxygen (O 2 ) gas instead of the NH 3  gas, or a titanium nitride film forming apparatus which uses a TiCl 4  gas as a source gas and a NH 3  gas as a reactant gas may be used. In addition, the film-forming apparatus may include a rotation mechanism for rotating each of the wafers W mounted on the rotary table  2 . Since the film thickness can be made uniform in both the X-axis direction and the Y-axis direction of the wafer W, the in-plane uniformity of the film thickness is improved when the wafer W is rotated to form a film. 
     [Verification Test 1] 
     The following test was conducted to verify the effect of the present disclosure. The film-forming apparatus according to the above-described embodiment was used to supply a DCS gas only by the main nozzle  41  and perform a film-formation process on the wafer W. As shown in  FIG. 10 , in the main nozzle  41 , the gas discharge holes  44  were arranged over a range d 0  including a section of 24 mm, from an inner peripheral edge close to the central side of the rotary table  2  in the passage region of the wafer W to the central side of the rotary table  2 , and a section of 26 mm from an outer peripheral edge close to the peripheral wall side of the vacuum vessel  1  in the passage region of the wafer W to the peripheral wall side of the vacuum vessel  1 . An example in which a mixed gas of the DCS gas having a flow rate of 1,000 sccm and the N 2  gas having a flow rate of 500 sccm was supplied from the main nozzle  41  is designated as Experimental Example 1-1. In addition, an example in which a mixed gas of the DCS gas having a flow rate of 600 sccm and the N 2  gas having a flow rate of 900 sccm was supplied from the main nozzle  41  is designated as Experimental Example 1-2, and an example in which a mixed gas of the DCS gas having a flow rate of 300 sccm and the N 2  gas having a flow rate of 1,200 sccm was supplied from the main nozzle  41  is designated as Experimental Example 1-3. 
     A heating temperature of the wafer W was set to 400 degrees C., a process pressure was set to 100 Pa, and flow rates of the Ar gas, the H 2  gas, and the NH 3  gas were set to 2,000 sccm, 600 sccm, and 300 sccm, respectively. The rotary table  2  was rotated at a rotational speed of 10 rpm and a cycle of the film-forming process shown in the embodiment was repeated 139 times to form a SiN film, and film thickness distribution of the SiN film formed on the wafer W was investigated in each of Experimental Examples 1-1 to 1-3. 
       FIG. 11  shows the results of the investigation. The results show the film thickness (nm) of the SiN film on the diameter of the wafer W in a direction (the X-axis direction: a downstream side in the rotational direction of the wafer W is defined at 0 mm) orthogonal to the main nozzle  41  in each of Experimental Examples 1-1 to 1-3. In addition,  FIG. 12  shows the film thickness (nm) of the SiN film on the diameter of the wafer W in a direction (the Y-axis direction) in which the main nozzle  41  extends in each of Experimental Examples 1-1 to 1-3. Further, the in-plane uniformity (%: ±[(maximum value of measured value−minimum value of measured value)/(average value of measured value×2)]×100) was obtained by each measured value in the X-axis direction and the Y-axis direction. 
     As shown in  FIGS. 11 and 12 , the in-plane uniformity of Experimental Examples 1-1 to 1-3 was at a low level of 0.99%, 1.17%, and 1.65%, respectively, in the direction (the X-axis direction) orthogonal to the main nozzle  41 , resulting in exhibiting the good in-plane uniformity of the film thickness. However, the in-plane uniformity of Experimental Examples 1-1 to 1-3 was at a high level of 5.46%, 6.01%, and 7.81%, respectively, in the Y-axis direction in which the main nozzle  41  extends, resulting in exhibiting the poor in-plane uniformity of the film thickness. 
     As shown in  FIGS. 11 and 12 , even in both the X-axis direction and the Y-axis direction, the film thickness was thickest in Experimental Example 1-1, and the film thickness was thicker in the order of Experimental Example 1-2 and Experimental Example 1-3. 
     As shown in  FIG. 12 , in the Y-axis direction, in all Experiment Examples 1-1 to 1-3, the film thickness of a portion of the wafer W at the outer peripheral side of the film-forming apparatus was thinner at a level of about 1 nm than the central-side portion of the wafer W. Further, in all Experimental Examples 1-1 to 1-3, the film thickness of a portion of the wafer W at the central side of the rotary table  2  was thinner at a level of about 0.5 nm than the central-side portion of the wafer W. 
     According to these results, it can be said that the film thickness becomes thicker depending on the concentration of the DCS gas. As a result, the NH 3  gas was sufficiently supplied, and the film thickness of the SiN film is not limited by a rate-limitation caused by the shortage of the NH 3  gas. Therefore, it is considered that the film thickness is determined by a difference in the adsorption amount of the DCS gas onto the wafer W, and the adsorption amount is changed by the partial pressure of DCS. 
     [Verification Test 2] 
     The following test was conducted to investigate the film thickness distribution of a film formed on the wafer W, depending on the position of the gas discharge holes  44  formed in the central-side auxiliary nozzle  43  and the flow rate of the discharged DCS gas. As shown in  FIG. 13 , an example in which 92 gas discharge holes  44  were formed in a range d 1  covering the section of 44 mm which includes the section of 24 mm from a position of an inner peripheral edge of the wafer W close to the central side of the rotary table  2  in the central-side auxiliary nozzle  43  to the central side of the rotary table  2  and the section of 20 mm from the position of the peripheral edge of the wafer W to the outer peripheral side of the rotary table  2 , is designated as Experimental Example 2-1. In addition, an example in which 52 gas discharge holes  44  were formed in a range d 2  covering the section of 24 mm from the position of the inner peripheral edge of the wafer W close to the central side of the rotary table  2  in the central-side auxiliary nozzle  43  to the central side of the rotary table  2 , is designated as Experimental Example 2-2. In addition, an example in which 24 gas discharge holes  44  were formed in a range d 3  covering the section of 14 mm spaced apart at a distance 10 to 24 mm from the inner peripheral edge of the wafer W close to the central side of the rotary table  2  in the central-side auxiliary nozzle  43  to the central side of the rotary table  2 , is designated as Experimental Example 2-3. 
     The DCS gas was supplied from the central-side auxiliary nozzle  43  at a flow rate of 20 sccm, a heating temperature of the wafer W was set to 400 degrees C., a process pressure was set to 100 Pa, and flow rates of the Ar gas, the H 2  gas and the NH 3  gas were set to 2,000 sccm, 600 sccm, and 300 sccm, respectively. The rotary table  2  was rotated at a rotational speed of 10 rpm and a cycle of the film-forming process shown in the embodiment was repeated 139 times to form a SiN film. The film thickness distribution of the SiN film formed on the wafer W was investigated in each of Experimental Examples 2-1 to 2-3. 
       FIG. 14  shows the results of the investigation. A position where a maximum value of the film thickness in Experimental Examples 2-1 to 2-3 was measured was a position closest to the central side of the rotary table  2  in Experimental Example 2-3. According to this result, it can be said that the film thickness can be made approximate to the film thickness distribution where the film thickness becomes thicker toward the central side of the rotary table  2 , by forming the gas discharge holes  44  at the central side of the rotary table  2  rather than the position of the inner peripheral edge of the wafer W close to the central side of the rotary table  2 . As shown in  FIG. 14 , an optimum range of the region in which the gas discharge holes  44  are formed was the range d 3  covering the section of 14 mm spaced apart at a distance 10 to 24 mm from the inner peripheral edge of the wafer W close to an inner periphery of the rotary table  2  in the central-side auxiliary nozzle  43  to the central side of the rotary table  2 . From this, the gas discharge holes  44  may be formed beyond a distance of 8 mm from the position of the peripheral edge of the wafer W to the outer peripheral side of the rotary table  2  in consideration of the margin. 
     In addition, by using the central-side auxiliary nozzle  43  shown in Experimental Example 2-3, the film thickness distribution of the film formed on the wafer W depending on the flow rates of the DCS gas and the N 2  gas discharged from the central-side auxiliary nozzle  43  was investigated. Except for the flow rate ratio (the flow rate of the DCS gas/the flow rate of the N 2  gas) of the DCS gas and the carrier gas (the N 2  gas) which was set to (20/0) sccm, (40/0) sccm, (20/200) sccm, and (20/400) sccm, examples set in the same manner as in Experimental Example 2-3 are designated as Experimental Examples 2-4, 2-5, 2-6, and 2-7, respectively. 
       FIG. 15  shows these results. A position where a maximum value of the film thickness in Experimental Examples 2-4 to 2-7 is measured was a position of the peripheral edge closest to the central side of the rotary table  2  in the wafer W in Experimental Example 2-4. According to this result, it can be said that the film thickness can be made approximate to the film thickness distribution where the film thickness becomes thicker toward the central side of the rotary table  2 , by decreasing the flow rate of the DCS gas and also reducing the flow rate of the carrier gas to increase the partial pressure of the DCS gas. 
     [Verification Test 3] 
     The following test was conducted to investigate the film thickness distribution of the film formed on the wafer W depending on an optimum formation position of the gas discharge holes  44  in the peripheral-side auxiliary nozzle  42  and a flow rate of the discharged DCS gas. As shown in  FIG. 16 , an example in which 110 gas discharge holes  44  were formed in a range d 4  covering the section of 60 mm which includes the section of 26 mm from a position of a peripheral edge of the wafer W close to the outer peripheral side of the rotary table  2  in the peripheral-side auxiliary nozzle  42  to the outer peripheral side of the rotary table  2 , and the section of 34 mm from the position of the peripheral edge of the wafer W to the central side of the rotary table  2 , is designated as Experimental Example 3-1. An example in which 60 gas discharge holes  44  were formed in a range d 5  covering the section of 26 mm from the position of the peripheral edge of the wafer W close to the outer peripheral side of the rotary table  2  in the peripheral-side auxiliary nozzle  42  to the outer peripheral side of the rotary table  2 , is designated as Experimental Example 3-2. An example in which 28 gas discharge holes  44  were formed in a range d 6  covering the section of 15 mm spaced apart at a distance 11 to 26 mm from the position of the peripheral edge of the wafer W close to the outer peripheral side of the rotary table  2  in the peripheral-side auxiliary nozzle  42  to the outer peripheral side of the rotary table  2 , is designated as Experimental Example 3-3. 
     The DCS gas was supplied from the peripheral-side auxiliary nozzle  42  at a flow rate of 20 sccm, a heating temperature of the wafer W was set to 400 degrees C., a process pressure was set to 100 Pa, and flow rates of the Ar gas, the H 2  gas, and the NH 3  gas were set to 2,000 sccm, 600 sccm, and 300 sccm, respectively. The rotary table  2  was rotated at a rotational speed of 10 rpm and a cycle of the film-forming process shown in the embodiment was repeated 139 times to form a SiN film. The film thickness distribution of the SiN film formed on the wafer W was investigated in each of Experimental Examples 3-1 to 3-3. 
       FIG. 17  shows the results of the investigation. A position where a maximum value of the film thickness in Experimental Examples 3-1 to 3-3 was measured was a position closest to the outer wall side of the vacuum vessel  1  in Experimental Example 3-3. According to this result, it can be said that the film thickness can be made approximate to the film thickness distribution where the film thickness becomes thicker toward the outer peripheral side of the rotary table  2 , by allowing the gas discharge holes  44  formed in the peripheral-side auxiliary nozzle  42  to be positioned at the outer peripheral side of the rotary table  2  rather than the peripheral edge of the wafer W close to the outer peripheral side of the rotary table  2 . As shown in  FIG. 17 , an optimum range of the region in which the gas discharge holes  44  are formed was the range d 6  covering the section of 15 mm spaced apart at a distance 11 to 26 mm from the position of the peripheral edge of the wafer W close to the outer peripheral side of the rotary table  2  in the peripheral-side auxiliary nozzle  42  to the outer peripheral side of the rotary table  2 . From this, the gas discharge holes  44  may be formed beyond a distance of 9 mm from the position of the peripheral edge of the wafer W to the outer peripheral side of the rotary table  2  in consideration of the margin. 
     In addition, by using the peripheral-side auxiliary nozzle  42  shown in Experimental Example 3-3, the film thickness distribution of the film formed on the wafer W depending on the flow rates of the DCS gas and the N 2  gas discharged from the peripheral-side auxiliary nozzle  42  was investigated. Except that the flow rate ratio (flow rate of the DCS gas/flow rate of the N 2  gas) of the DCS gas and the carrier gas (the N 2  gas) was set to (20/0) sccm, (40/0) sccm, (20/200) sccm, and (20/400) sccm, examples set in the same manner as in Experimental Example 3-3 are designated as Experimental Examples 3-4, 3-5, 3-6, and 3-7, respectively. 
       FIG. 18  shows these results. In Experimental Example 3-4, a position where a maximum value of the film thickness in Experimental Examples 3-4 to 3-7 was measured was a position closest to the outer peripheral side of the rotary table  2  in the peripheral edge of the wafer W. According to this result, it can be said that the film thickness can be made approximate to the film thickness distribution where the film thickness becomes thicker toward the peripheral edge close to the outer peripheral side of the rotary table  2  in the wafer W, by decreasing the flow rate of the DCS gas and also reducing the flow rate of the N 2  gas to increase the partial pressure of the DCS gas. 
     The present disclosure relates to a technique for supplying a source gas to a substrate mounted on a rotary table, using gas nozzles that extend in a direction intersecting with a movement path of the rotary table and include gas discharge holes formed to discharge gases downward. Defining a central side and a peripheral wall side of a vacuum vessel as an inner side and an outer side, in addition to a main nozzle for supplying the source gas to the entire passage region of the substrate when viewed in the inward and outward directions, auxiliary nozzles may be used to compensate for the shortage of the source gas supplied from the main nozzle. Further, the central-side auxiliary nozzle supplies the source gas to an inner region of the passage region of the substrate on the rotary table, and the peripheral-side auxiliary nozzle supplies the source gas to an outer region of the passage region of the substrate on the rotary table. Thus, it is possible to supply the activated gas to peripheral edges close to the inner and outer regions of the substrate where the activity of the source gas is low when being supplied from the main nozzle. This improves the in-plane uniformity of a film formed on the substrate. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosures. Indeed, the embodiments described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the disclosures. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosures.