Patent Publication Number: US-11047048-B2

Title: Method of manufacturing semiconductor device, substrate processing apparatus, and recording medium

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from U.S. Non-Provisional patent application Ser. No. 16/190,834, filed Nov. 14, 2018, and Japanese Patent Application No. 2017-220187, filed on Nov. 15, 2017, the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a method of manufacturing a semiconductor device, a substrate processing apparatus, and a recording medium. 
     BACKGROUND 
     As one of the processes of manufacturing a semiconductor device, a process of forming a film on a substrate may be performed. 
     SUMMARY 
     Some embodiments of the present disclosure provide a technique capable of controlling the substrate in-plane film thickness distribution of a film formed on a substrate. 
     According to one embodiment of the present disclosure, there is provided a technique that includes providing a substrate; and forming a film on the substrate by performing: supplying a first inert gas from a first supplier to the substrate; supplying a second inert gas from a second supplier to the substrate; and supplying a first processing gas from a third supplier, which is installed on an opposite side of the first supplier across a straight line passing through the second supplier and a center of the substrate, to the substrate, wherein in the act of forming the film, a substrate in-plane film thickness distribution of the film formed on the substrate is adjusted by controlling a balance between a flow rate of the first inert gas supplied from the first supplier and a flow rate of the second inert gas supplied from the second supplier. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic configuration diagram of a vertical process furnace of a substrate processing apparatus suitably used in an embodiment of the present disclosure, in which a part of the process furnace is shown in a vertical sectional view. 
         FIG. 2  is a schematic configuration diagram of a part of a vertical process furnace of a substrate processing apparatus suitably used in an embodiment of the present disclosure, in which a part of the process furnace is shown in a sectional view taken along line A-A in  FIG. 1 . 
         FIG. 3  is a schematic configuration diagram of a controller of a substrate processing apparatus suitably used in an embodiment of the present disclosure, in which a control system of the controller is shown in a block diagram. 
         FIG. 4  is a diagram showing a film-forming sequence according to an embodiment of the present disclosure. 
         FIGS. 5A and 5B  are horizontal sectional views showing modifications of a vertical process furnace, respectively, in which a reaction tube, a buffer chamber, a nozzle and the like are shown in a partially extracted state. 
         FIGS. 6A and 6B  are diagrams showing film thickness measurement results at the outer peripheral portions of substrates for the films formed on the substrates. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure will be now described in detail with reference to the drawings. Like or equivalent components, members, and processes illustrated in each drawing are given like reference numerals and a repeated description thereof will be properly omitted. Further, the embodiments are presented by way of example only, and are not intended to limit the present disclosure, and any feature or combination thereof described in the embodiments may not necessarily be essential to the present disclosure. 
     One Embodiment of the Present Disclosure 
     An embodiment of the present disclosure will now be described with reference to  FIGS. 1 to 4 . 
     (1) Configuration of Substrate Processing Apparatus 
     As shown in  FIG. 1 , a process furnace  202  includes a heater  207  as a heating mechanism (temperature adjustment part). The heater  207  has a cylindrical shape and is vertically installed by being supported by a holding plate. The heater  207  also functions as an activation mechanism (excitation part) that thermally activates (excites) a gas. 
     Inside the heater  207 , a reaction tube  203  is arranged concentrically with the heater  207 . The reaction tube  203  is made of a heat-resistant material such as, for example, quartz (SiO 2 ) or silicon carbide (SiC) and is formed in a cylindrical shape with its upper end closed and its lower end opened. Under the reaction tube  203 , a manifold  209  is disposed concentrically with the reaction tube  203 . The manifold  209  is made of a metallic material such as, for example, stainless steel (SUS) or the like and is formed in a cylindrical shape with its upper and lower ends opened. The upper end portion of the manifold  209  is engaged with the lower end portion of the reaction tube  203  and is configured to support the reaction tube  203 . An O-ring  220   a  as a seal member is installed between the manifold  209  and the reaction tube  203 . The reaction tube  203  is vertically installed just like the heater  207 . A process container (reaction container) mainly includes the reaction tube  203  and the manifold  209 . A process chamber  201  is formed in the hollow portion of the process container. The process chamber  201  is configured to be able to accommodate wafers  200  as substrates. A process on the wafers  200  is performed in the process chamber  201 . 
     In the process chamber  201 , nozzles  249   a  to  249   c  as first to third suppliers are respectively installed so as to penetrate the side wall of the manifold  209 . Gas supply pipes  232   a  to  232   c  are connected to the nozzles  249   a  to  249   c , respectively. The nozzles  249   a  to  249   c  are respectively different nozzles. Each of the nozzles  249   a  and  249   c  is installed adjacent to the nozzle  249   b.    
     Mass flow controllers (MFCs)  241   a  to  241   c  as flow rate controllers (flow rate control parts) and valves  243   a  to  243   c  as opening/closing valves are respectively installed in the gas supply pipes  232   a  to  232   c  sequentially from the upstream side of a gas flow. Gas supply pipes  232   d  and  232   e  are connected to the gas supply pipes  232   a  and  232   b , respectively, on the downstream side of the valves  243   a  and  243   b . Gas supply pipes  232   f  and  232   g  are respectively connected to the gas supply pipe  232   c  on the downstream of the valve  243   c . In the gas supply pipes  232   d  to  232   g , MFCs  241   d  to  241   g  and valves  243   d  to  243   g  are installed sequentially from the upstream side of a gas flow. 
     As shown in  FIG. 2 , the nozzles  249   a  to  249   c  are arranged in an annular space in a plan view between the inner wall of the reaction tube  203  and the wafers  200  and are installed so as to extend upward in the arrangement direction of the wafers  200  from the lower portion of the inner wall of the reaction tube  203  to the upper portion thereof. In other words, the nozzles  249   a  to  249   c  are respectively installed in a region existing on the side of a wafer arrangement region, in which the wafers  200  are arranged, and horizontally surrounding the wafer arrangement region, so as to extend along the wafer arrangement region. In a plan view, the nozzle  249   b  is disposed so as to be opposed to a below-described exhaust port  231   a  on a straight line across the centers of the wafers  200 , which is interposed between the nozzle  249   b  and the exhaust port  231   a , loaded into the process chamber  201 . The nozzles  249   a  and  249   c  are arranged so as to sandwich a straight line L, that passes through the nozzle  249   b  and the center of the exhaust port  231   a , from both sides along the inner wall of the reaction tube  203  (the outer peripheral portions of the wafers  200 ). The straight line L is also a straight line passing through the nozzle  249   b  and the centers of the wafers  200 . That is, it can be said that the nozzle  249   c  is installed on the side opposite to the nozzle  249   a  across the straight line L. The nozzles  249   a  and  249   c  are arranged line-symmetrically with respect to the straight line L as an axis of symmetry. Gas supply holes  250   a  to  250   c  for supplying gases are formed on the side surfaces of the nozzles  249   a  to  249   c , respectively. Each of the gas supply holes  250   a  to  250   c  is opened so as to oppose (face) the exhaust port  231   a  in a plan view and is capable of supplying a gas toward the wafers  200 . The gas supply holes  250   a  to  250   c  are formed in a plural number from the lower portion to the upper portion of the reaction tube  203 . 
     From the gas supply pipe  232   a , a processing gas (second processing gas), for example, a silane-based gas containing silicon (Si) as a main element constituting a seed layer to be described later is supplied into the process chamber  201  via the MFC  241   a , the valve  243   a , and the nozzle  249   a . As the silane-based gas, it may be possible to use a halogen-element-free silicon hydride gas, for example, a disilane (Si 2 H 6 , abbreviation: DS) gas. 
     From the gas supply pipe  232   b , a processing gas (third processing gas), for example, a gas containing Si and a halogen element, i.e., a halosilane-based gas is supplied into the process chamber  201  via the MFC  241   b , the valve  243   b  and the nozzle  249   b . The halogen element includes chlorine (Cl), fluorine (F), bromine (Br), iodine (I), and the like. As the halosilane-based gas, it may be possible to use a chlorosilane-based gas containing Si and Cl, for example, a dichlorosilane (SiH 2 Cl 2 , abbreviation: DCS) gas. 
     From the gas supply pipe  232   c , a processing gas (first processing gas), for example, a silane-based gas containing Si as a main element constituting a film formed on each of the wafers  200  is supplied into the process chamber  201  via the MFC  241   c , the valve  243   c  and the nozzle  249   c . As the silane-based gas, it may be possible to use a halogen-element-free silicon hydride gas, for example, a monosilane (SiH 4 , abbreviation: MS) gas. 
     From the gas supply pipes  232   d  to  232   f , an inert gas, for example, a nitrogen (N 2 ) gas is supplied into the process chamber  201  via the MFCs  241   d  to  241   f , the valves  243   d  to  243   f , the gas supply pipes  232   a  to  232   c  and the nozzles  249   a  to  249   c . The N 2  gas functions as a purge gas, a carrier gas, a dilution gas and the like, and further functions as a film thickness distribution control gas for controlling the in-plane film thickness distribution of the film formed on each of the wafers  200 . 
     From the gas supply pipe  232   g , a dopant gas, for example, a gas containing an impurity (dopant) is supplied into the process chamber  201  via the MFC  241   g , the valve  243   g , the gas supply pipe  232   c  and the nozzle  249   c . As the dopant gas, it is possible to use a gas containing an element which is one of a group III element (group 13 element) and a group V element (group 15 element) and which becomes solid by itself, for example, a phosphine (PH 3 , abbreviation: PH) gas which is a gas containing a group V element. 
     A processing gas supply system mainly includes the gas supply pipes  232   a  to  232   c , the MFCs  241   a  to  241   c  and the valves  243   a  to  243   c . The gas supply pipe  232   g , the MFC  241   g  and the valve  243   g  may be included in the processing gas supply system. Further, an inert gas supply system mainly includes the gas supply pipes  232   d  to  232   f , the MFCs  241   d  to  241   f  and the valves  243   d  to  243   f . In this specification, the gas supply system including the gas supply pipe  232   d , the MFC  241   d  and the valve  243   d  is also referred to as a first supply system. The gas supply pipe  232   a , the MFC  241   a  and the valve  243   a  may be included in the first supply system. The gas supply system including the gas supply pipe  232   e , the MFC  241   e  and the valve  243   e  is also referred to as a second supply system. The gas supply pipe  232   b , the MFC  241   b  and the valve  243   b  may be included in the second supply system. The gas supply system including the gas supply pipe  232   c , the MFC  241   c  and the valve  243   c  is also referred to as a third supply system. The gas supply pipes  232   g  and  232   f , the MFCs  241   g  and  241   f , and the valves  243   g  and  243   f  may be included in the third supply system. 
     One or all of the above-mentioned various supply systems may be configured as an integrated supply system  248  formed by integrating the valves  243   a  to  243   g , the MFCs  241   a  to  241   g  and the like. The integrated supply system  248  is connected to each of the gas supply pipes  232   a  to  232   g  and is configured so that the supply operations of the various gases to the gas supply pipes  232   a  to  232   g , i.e., the opening/closing operation of the valves  243   a  to  243   g , the flow rate adjustment operation of the MFCs  241   a  to  241   g , and the like can be controlled by a controller  121  which will be described later. The integrated supply system  248  may be formed of one-piece-type or split-type integrated units. The integrated supply system  248  may be attached to and detached from the gas supply pipes  232   a  to  232   g  or the like on an integrated unit basis. The maintenance, replacement, expansion or the like of the integrated supply system  248  may be performed on an integrated unit basis. 
     An exhaust port  231   a  for exhausting the atmosphere inside the process chamber  201  is installed in the lower portion of the side wall of the reaction tube  203 . As shown in  FIG. 2 , the exhaust port  231   a  is installed at a position opposed to (facing) the nozzles  249   a  to  249   c  (gas supply holes  250   a  to  250   c ) across the wafers  200  in a plan view. The exhaust port  231   a  may be installed to extend from the lower portion to the upper portion of the side wall of the reaction tube  203 , i.e., along the wafer arrangement region. An exhaust pipe  231  is connected to the exhaust port  231   a . A vacuum pump  246  as a vacuum-exhaust device is connected to the exhaust pipe  231  via a pressure sensor  245  as a pressure detector (pressure detection part) for detecting the pressure inside the process chamber  201  and an APC (Auto Pressure Controller) valve  244  as a pressure regulator (pressure regulation part). The APC valve  244  is configured so that the vacuum-exhaust of the interior of the process chamber  201  and the stop of the vacuum-exhaust can be performed by opening and closing the APC valve  244  in a state in which the vacuum pump  246  is operated, and so that the pressure inside the process chamber  201  can be adjusted by adjusting the valve opening degree based on the pressure information detected by the pressure sensor  245  in a state in which the vacuum pump  246  is operated. An exhaust system mainly includes the exhaust pipe  231 , the APC valve  244  and the pressure sensor  245 . The vacuum pump  246  may be included in the exhaust system. 
     A seal cap  219  as a furnace opening lid capable of airtightly closing the lower end opening of the manifold  209  is installed below the manifold  209 . The seal cap  219  is made of a metallic material such as, for example, stainless steel or the like and is formed in a disc shape. On the upper surface of the seal cap  219 , there is installed an O-ring  220   b  as a seal member which makes contact with the lower end of the manifold  209 . Under the seal cap  219 , there is installed a rotation mechanism  267  for rotating a boat  217  to be described later. A rotating shaft  255  of the rotation mechanism  267  passes through the seal cap  219  and is connected to the boat  217 . The rotation mechanism  267  is configured to rotate the wafers  200  by rotating the boat  217 . The seal cap  219  is configured to be raised and lowered in the vertical direction by a boat elevator  115  as an elevating mechanism installed outside the reaction tube  203 . The boat elevator  115  is configured as a transfer device (transfer mechanism) that loads and unloads (transfers) the wafers  200  into and out of the process chamber  201  by raising and lowering the seal cap  219 . Under the manifold  209 , there is installed a shutter  219   s  as a furnace opening lid capable of airtightly closing the lower end opening of the manifold  209  in a state in which the seal cap  219  is lowered to unload the boat  217  from the process chamber  201 . The shutter  219   s  is made of a metallic material such as, for example, stainless steel or the like and is formed in a disk shape. On the upper surface of the shutter  219   s , there is installed an O-ring  220   c  as a seal member which makes contact with the lower end of the manifold  209 . The opening/closing operations (the elevating operation, the rotating operation and the like) of the shutter  219   s  are controlled by a shutter opening/closing mechanism  115   s.    
     The boat  217  serving as a substrate support is configured to support a plurality of wafers  200 , e.g., 25 to 200 wafers  200  in such a state that the wafers  200  are arranged in a horizontal posture and in multiple stages along a vertical direction with the centers of the wafers  200  aligned with one another. The boat  217  is made of a heat-resistant material such as, for example, quartz or SiC. Heat insulating plates  218  made of a heat-resistant material such as, for example, quartz or SiC are disposed at multiple stages in the lower portion of the boat  217 . 
     In the reaction tube  203 , there is installed a temperature sensor  263  as a temperature detector. By adjusting the state of supplying electric power to the heater  207  based on the temperature information detected by the temperature sensor  263 , the temperature inside the process chamber  201  is controlled to have a desired temperature distribution. The temperature sensor  263  is installed along the inner wall of the reaction tube  203 . 
     As shown in  FIG. 3 , the controller  121  as a control part (control means) is configured as a computer including a CPU (Central Processing Unit)  121   a , a RAM (Random Access Memory)  121   b , a memory device  121   c  and an I/O port  121   d . The RAM  121   b , the memory device  121   c  and the I/O port  121   d  are configured to exchange data with the CPU  121   a  via an internal bus  121   e . An input/output device  122  formed of, for example, a touch panel or the like is connected to the controller  121 . 
     The memory device  121   c  is configured by, for example, a flash memory, a hard disc drive (HDD), or the like. A control program for controlling the operations of the substrate processing apparatus, a process recipe in which sequences and conditions of a substrate processing process to be described later are written, and the like are readably stored in the memory device  121   c . The process recipe functions as a program for causing the controller  121  to execute each sequence in the substrate processing process, which will be described later, to obtain a predetermined result. Hereinafter, the process recipe and the control program will be generally and simply referred to as a program. Further, the process recipe will be simply referred to as a recipe. When the term “program” is used herein, it may indicate a case of including only the process recipe, a case of including only the control program, or a case of including both the process recipe and the control program. The RAM  121   b  is configured as a memory area (work area) in which a program or data read by the CPU  121   a  is temporarily stored. 
     The I/O port  121   d  is connected to the MFCs  241   a  to  241   g , the valves  243   a  to  243   g , the pressure sensor  245 , the APC valve  244 , the vacuum pump  246 , the temperature sensor  263 , the heater  207 , the rotation mechanism  267 , the boat elevator  115 , the shutter opening/closing mechanism  115   s , and the like. 
     The CPU  121   a  is configured to read the control program from the memory device  121   c  and execute the same. The CPU  121   a  is also configured to read the process recipe from the memory device  121   c  according to an input of an operation command from the input/output device  122  or the like. The CPU  121   a  is configured to control, according to the contents of the process recipe thus read, the flow rate adjustment operation of various gases by the MFCs  241   a  to  241   g , the opening/closing operation of the valves  243   a  to  243   g , the opening/closing operation of the APC valve  244 , the pressure regulation operation performed by the APC valve  244  based on the pressure sensor  245 , the driving and stopping of the vacuum pump  246 , the temperature adjustment operation performed by the heater  207  based on the temperature sensor  263 , the operation of rotating the boat  217  with the rotation mechanism  267  and adjusting the rotation speed of the boat  217 , the operation of raising and lowering the boat  217  with the boat elevator  115 , the opening/closing operation of the shutter  219   s  by the shutter opening/closing mechanism  115   s , and the like. 
     The controller  121  may be configured by installing, in a computer, the above-described program stored in an external memory device  123 . The external memory device  123  includes, for example, a magnetic disk such as an HDD or the like, an optical disk such as a CD or the like, a magneto-optical disk such as an MO or the like, a semiconductor memory such as a USB memory or the like, and so forth. The memory device  121   c  or the external memory device  123  is configured as a non-transitory computer-readable recording medium. Hereinafter, the memory device  121   c  and the external memory device  123  will be generally and simply referred to as a recording medium. When the term “recording medium” is used herein, it may indicate a case of including only the memory device  121   c , a case of including only the external memory device  123 , or a case of including both the memory device  121   c  and the external memory device  123 . The provision of the program to the computer may be performed by using a communication means such as the Internet or a dedicated line without using the external memory device  123 . 
     (2) Substrate Processing Process 
     An example of a substrate processing sequence for forming a film on a substrate, i.e., an example of a film formation sequence will be described with reference to  FIG. 4  as one of the processes of manufacturing a semiconductor device using the substrate processing apparatus described above. In the following description, the operations of the respective parts constituting the substrate processing apparatus are controlled by the controller  121 . 
     In the film formation sequence shown in  FIG. 4 , there is performed a step (Si film formation step) of forming a Si-containing film added (doped) with P, i.e., a P-doped Si film, on a wafer  200 , by preparing the wafer  200  as a substrate, then supplying an N 2  gas as an inert gas to the wafer  200  from a nozzle  249   a  as a first supplier, supplying an N 2  gas as an inert gas to the wafer  200  from a nozzle  249   b  as a second supplier, and supplying an MS gas as a first processing gas and a PH gas as a dopant gas to the wafer  200  from a nozzle  249   c  as a third supplier installed on the opposite side of the nozzle  249   a  across a straight line L passing through the nozzle  249   b  and the center of the wafer  200  in a plan view. In this specification, the P-doped Si film is also simply referred to as a Si film. 
     In the film formation sequence shown in  FIG. 4 , after preparing the wafer  200  and before performing the Si film formation step described above, there is performed a step (seed layer formation step) of forming a layer containing Si, i.e., a Si layer as a seed layer on the wafer  200 , by supplying a DS gas as a second processing gas to the wafer  200  from the nozzle  249   a , supplying an N 2  gas to the wafer  200  from the nozzle  249   b  and supplying an N 2  gas to the wafer  200  from the nozzle  249   c . Hereinafter, this Si layer is also referred to as a Si seed layer. 
     Specifically, in the seed layer formation step, a cycle of alternately performing step 1 of supplying a DCS gas as a third processing gas to the wafer  200  from any one of the nozzles  249   a  to  249   c  (in this case, the nozzle  249   b ) and step 2 of supplying a DS gas to the wafer  200  from the nozzle  249   a , supplying an N 2  gas to the wafer  200  from the nozzle  249   b  and supplying an N 2  gas to the wafer  200  from the nozzle  249   c  is performed a predetermined number of times. 
     In the above-described Si film formation step, the wafer in-plane film thickness distribution of the Si film formed on the wafer  200  (hereinafter also simply referred to as an in-plane film thickness distribution) is adjusted by controlling the balance between the flow rate of the N 2  gas supplied from the nozzle  249   a  and the flow rate of the N 2  gas supplied from the nozzle  249   b.    
     As an example, description will now be made on an example where a bare wafer having a small surface area with no concavo-convex structure formed on the surface thereof is used as the wafer  200  and the in-plane film thickness distribution of the Si film is adjusted by the film formation sequence and the flow rate control described above. In this specification, the in-plane film thickness distribution of a film which is thickest at the central portion of the wafer  200  and gradually becomes thinner toward the outer peripheral portion (peripheral edge portion) is also referred to as a center convex distribution. Further, the in-plane film thickness distribution of a film which is thinnest at the central portion of the wafer  200  and becomes gradually thicker towards the outer peripheral portion is also referred to as a center concave distribution. Moreover, the film thickness distribution of a flat film with little film thickness variation from the central portion to the outer peripheral portion of the wafer  200  is also referred to as a flat distribution. If a film having a center convex distribution can be formed on a bare wafer, it is possible to form a film having a flat distribution on a pattern wafer (product wafer) having a large surface area with a fine concavo-convex structure formed on the surface thereof. 
     In this specification, the film formation sequence shown in  FIG. 4  may be denoted as follows for the sake of convenience. The same notation is also used in the following description of modifications and the like.
 
(DCS→DS)× n →MS+PH⇒P-doped Si
 
     When the term “wafer” is used herein, it may refer to “a wafer itself” or “a laminated body of a wafer and a predetermined layer or film formed on the surface of the wafer.” Furthermore, when the phrase “a surface of a wafer” is used herein, it may refer to “a surface of a wafer itself” or “a surface of a predetermined layer or the like formed on a wafer.” Moreover, the expression “a predetermined layer is formed on a wafer” as used herein may mean that “a predetermined layer is directly formed on a surface of a wafer itself” or that “a predetermined layer is formed on a layer or the like formed on a wafer.” In addition, when the term “substrate” is used herein, it may be synonymous with the term “wafer.” 
     (Wafer Charging and Boat Loading) 
     When a plurality of wafers  200  is charged on the boat  217  (wafer charging), the shutter  219   s  is moved by the shutter opening/closing mechanism  115   s  to open the lower end opening of the manifold  209  (shutter open). Thereafter, as shown in  FIG. 1 , the boat  217  supporting the plurality of wafers  200  is lifted up by the boat elevator  115  and is loaded into the process chamber  201  (boat loading). In this state, the seal cap  219  seals the lower end of the manifold  209  via the O-ring  220   b.    
     (Pressure Regulation and Temperature Adjustment) 
     The interior of the process chamber  201 , namely the space in which the wafers  200  exist, is vacuum-exhausted (depressurization-exhausted) by the vacuum pump  246  so as to reach a desired pressure (degree of vacuum). At this time, the pressure in the process chamber  201  is measured by the pressure sensor  245 . The APC valve  244  is feedback-controlled based on the measured pressure information. The wafers  200  in the process chamber  201  are heated by the heater  207  to a desired film-forming temperature. At this time, the state of supplying electric power to the heater  207  is feedback-controlled based on the temperature information detected by the temperature sensor  263  such that the interior of the process chamber  201  has a desired temperature distribution. In addition, the rotation of the wafers  200  by the rotation mechanism  267  begins. The exhaustion of the process chamber  201  and the heating and rotation of the wafers  200  may be continuously performed at least until the processing of the wafers  200  is completed. 
     (Seed Layer Formation Step) 
     Thereafter, the following steps 1 and 2 are sequentially executed. 
     [Step 1] 
     In this step, a DCS gas is supplied from the nozzle  249   b  to the wafer  200  in the process chamber  201 , and an N 2  gas is supplied from each of the nozzles  249   a  and  249   c  to the wafer  200 . 
     Specifically, the valve  243   b  is opened and the DCS gas is allowed to flow into the gas supply pipe  232   b . The flow rate of the DCS gas is adjusted by the MFC  241   b . The DCS gas is supplied into the process chamber  201  via the nozzle  249   b  and is exhausted from the exhaust port  231   a . At this time, the DCS gas is supplied to the wafer  200 . Furthermore, at this time, the valves  243   d  and  243   f  are opened and the N 2  gas is supplied into the process chamber  201  via each of the nozzles  249   a  and  249   c.    
     By supplying the DCS gas to the wafer  200  under the processing conditions to be described later, it is possible to remove a natural oxide film, impurities, etc. from the surface of the wafer  200  by the treatment action (etching action) possessed by the DCS gas. This makes it possible to clean the surface of the wafer  200 . Thus, the surface of the wafer  200  can become a surface on which the adsorption of Si, i.e., the formation of a seed layer easily proceeds in step 2 to be described later. 
     After the surface of the wafer  200  is cleaned, the valve  243   b  is closed and the supply of the DCS gas into the process chamber  201  is stopped. Then, the inside of the process chamber  201  is vacuum-exhausted and the gas or the like remaining in the process chamber  201  is removed from the inside of the process chamber  201 . At this time, the valves  243   d  to  243   f  are opened and the N 2  gas is supplied into the process chamber  201  via the nozzles  249   a  to  249   c . The N 2  gas supplied from the nozzles  249   a  to  249   c  acts as a purge gas, whereby the interior of the process chamber  201  is purged (purging step). 
     [Step 2] 
     After step 1 is finished, a DS gas is supplied from the nozzle  249   a  to the surface of the wafer  200  existing in the process chamber  201 , i.e., the surface of the cleaned wafer  200 , and an N 2  gas is supplied from each of the nozzles  249   b  and  249   c.    
     Specifically, the valve  243   a  is opened and the DS gas is allowed to flow into the gas supply pipe  232   a . The flow rate of the DS gas is adjusted by the MFC  241   a . The DS gas is supplied into the process chamber  201  via the nozzle  249   a  and is exhausted from the exhaust port  231   a . At this time, the DS gas is supplied to the wafer  200 . Furthermore, at this time, the valves  243   e  and  243   f  are opened and the N 2  gas is supplied into the process chamber  201  via each of the nozzles  249   b  and  249   c.    
     By supplying the DS gas to the wafer  200  under the processing conditions to be described later, it is possible to allow Si contained in the DS gas to be adsorbed on the surface of the wafer  200  cleaned in step 1 and to form seeds (nuclei) on the surface of the wafer  200 . Under the processing conditions to be described later, the crystal structure of the nuclei formed on the surface of the wafer  200  is amorphous. 
     After the nucleus is formed on the surface of the wafer  200 , the valve  243   a  is closed and the supply of the DS gas into the process chamber  201  is stopped. Then, the gas or the like remaining in the process chamber  201  is removed from the inside of the process chamber  201  by the same processing procedure as in the purging step of step 1. 
     [Performed a Predetermined Number of Times] 
     By performing a cycle, which performs the above-described steps 1 and 2 alternately, i.e., non-synchronously without synchronizing steps 1 and 2, a predetermined number of times (n times where n is an integer of 1 or more), it is possible to form a seed layer having the aforementioned nuclei arranged at a high density, i.e., an Si seed layer on the wafer  200 . 
     An example of processing conditions used in step 1 is described as follows. 
     DCS gas supply flow rate: 10 to 1000 sccm 
     DCS gas supply time: 0.5 to 10 minutes 
     N 2  gas supply flow rate (per gas supply pipe): 10 to 10000 sccm 
     Processing temperature (first temperature): 350 to 450 degrees C. 
     Processing pressure: 400 to 1000 Pa 
     An example of processing conditions used in step 2 is described as follows. 
     DS gas supply flow rate: 10 to 1000 sccm 
     DS gas supply time: 0.5 to 10 minutes 
     Other processing conditions are the same as the processing conditions used in step 1. 
     In step 1, as the third processing gas, in addition to the DCS gas, it may be possible to use a chlorosilane-based gas such as a monochlorosilane (SiH 3 Cl, abbreviation: MCS) gas, a tetrachlorosilane (SiCl 4 , abbreviation: STC) gas, a trichlorosilane (SiHCl 3 , abbreviation: TCS) gas, a hexachlorodisilane (Si 2 Cl 6 , abbreviation: HCDS) gas, an octachlorotrisilane (Si 3 Cl 8 , abbreviation: OCTS) gas or the like. Furthermore, as the third processing gas, it may be possible to use a tetrafluorosilane (SiF 4 ) gas, a tetrabromosilane (SiBr 4 ) gas, a tetraiodosilane (SiI 4 ) gas or the like. That is, as the third processing gas, in addition to the chlorosilane-based gas, it may be possible to use a halosilane-based gas such as a fluorosilane-based gas, a bromosilane-based gas, an iodosilane-based gas or the like. In addition, as the third processing gas, it may be possible to use an Si-free halogen-based gas such as a hydrogen chloride (HCl) gas, a chlorine (Cl 2 ) gas, a trichloroborane (BCl 3 ) gas, a chlorine fluoride (ClF 3 ) gas or the like. 
     In step 2, as the second processing gas, in addition to the DS gas, it may be possible to use a silicon hydride gas such as an MS gas, a trisilane (Si 3 H 8 ) gas, a tetrasilane (Si 4 H 10 ) gas, a pentasilane (Si 5 H 12 ) gas, a hexasilane (Si 6 H 14 ) gas or the like. 
     As the inert gas, in addition to the N 2  gas, it may be possible to use a rare gas such as an Ar gas, a He gas, a Ne gas, a Xe gas or the like. This also applies to a temperature raising step, a Si film formation step and the like which will be described later. 
     (Temperature Raising Step) 
     After the seed layer formation step is finished, the output of the heater  207  is adjusted so that the temperature inside the process chamber  201  is changed to a second temperature higher than the aforementioned first temperature. When this step is performed, the valves  243   d  to  243   f  are opened and the N 2  gas is supplied into the process chamber  201  via the nozzles  249   a  to  249   c  to purge the inside of the process chamber  201 . After the temperature inside the process chamber  201  reaches the second temperature and becomes stable, the Si film formation step to be described later is started. 
     (Si Film Formation Step) 
     In this step, an MS gas and a PH gas are supplied from the nozzle  249   c  to the wafer  200  in the process chamber  201 , i.e., the surface of the seed layer formed on the wafer  200 , and an N 2  gas is supplied from each of the nozzles  249   a  and  249   b.    
     Specifically, the valve  243   c  is opened and the MS gas is allowed to flow into the gas supply pipe  232   c . The flow rate of the MS gas is adjusted by the MFC  241   c . The MS gas is supplied into the process chamber  201  via the nozzle  249   c  and is exhausted from the exhaust port  231   a . At this time, the valve  243   g  is opened and the PH gas is allowed to flow into the gas supply pipe  232   g . The flow rate of the PH gas is adjusted by the MFC  241   g . The PH gas is supplied into the process chamber  201  via the gas supply pipe  232   c  and the nozzle  249   c  and is exhausted from the exhaust port  231   a . At this time, the MS gas and the PH gas are supplied simultaneously to the wafer  200 . Furthermore, at this time, the valves  243   d  and  243   e  are opened and the N 2  gas is supplied into the process chamber  201  via each of the nozzles  249   a  and  249   b.    
     By supplying the MS gas and the PH gas to the wafer  200  from the nozzle  249   c  under the processing conditions described later, it is possible to cause Si to be adsorbed (deposited) on the surface of the wafer  200 , i.e., on the seed layer formed on the wafer  200 , thereby forming a P-doped Si film. Under the processing conditions described later, the crystal structure of the Si film formed on the wafer  200  becomes amorphous, polycrystalline or an amorphous/polycrystalline mixed structure. 
     When supplying the MS gas or the PH gas (hereinafter also referred to as MS gas or the like) to the wafer  200 , the balance between the flow rate of the N 2  gas supplied from the nozzle  249   a  and the flow rate of the N 2  gas supplied from the nozzle  249   b  is controlled. Specifically, for example, the flow rate of the N 2  gas supplied from the nozzle  249   a  is made different from the flow rate of the N 2  gas supplied from the nozzle  249   b . This makes it possible to adjust the in-plane film thickness distribution of the Si film formed on the wafer  200 . 
     In the film formation sequence shown in  FIG. 4 , as an example, there is shown a case where the flow rate of the N 2  gas supplied from the nozzle  249   a  is made larger than the flow rate of the N 2  gas supplied from the nozzle  249   b . In this case, for example, the flow rate of the N 2  gas supplied from the nozzle  249   a  is set to 500 to 2000 sccm and the flow rate of the N 2  gas supplied from the nozzle  249   b  is set to 10 to 400 sccm. By controlling the flow rate balance in this way, it is possible to control the wafer in-plane concentration distribution (partial pressure distribution) of the MS gas or the like supplied to the wafer  200 , i.e., the supply amount distribution of the MS gas or the like in the wafer plane. More specifically, the concentration (supply amount) of the MS gas or the like supplied to the central portion of the wafer  200  may be controlled in an increasing direction, and the concentration (supply amount) of the MS gas or the like supplied to the outer peripheral portion of the wafer  200  is controlled in a decreasing direction. Depending on the degree of the control, the concentration (supply amount) of the MS gas or the like supplied to the central portion of the wafer  200  may be set to the same level as the concentration (supply amount) of the MS gas or the like supplied to the outer peripheral portion of the wafer  200 , or may be set to be larger than the concentration (supply amount) of the MS gas or the like supplied to the outer peripheral portion of the wafer  200 . As a result, it becomes possible to bring the in-plane film thickness distribution of the Si film formed on the wafer  200  closer to a flat distribution or to a center convex distribution from a center concave distribution. 
     After the Si film having a desired in-plane film thickness distribution is formed on the wafer  200 , the valves  243   c  and  243   g  are closed and the supply of the MS gas and the PH gas into the process chamber  201  is stopped. Then, the gas and the like remaining in the process chamber  201  are removed from the inside of the process chamber  201  by the same processing procedure as that of the purging step of the above-described step 1. 
     An example of processing conditions used in the Si film formation step is described as follows. 
     MS gas supply flow rate: 10 to 2000 sccm 
     PH gas supply flow rate: 0.1 to 500 sccm 
     MS gas and PH gas supply time: 1 to 300 minutes 
     N 2  gas supply flow rate (per gas supply pipe): 10 to 20000 sccm 
     Processing temperature (second temperature): 500 to 650 degrees C. 
     Processing pressure: 30 to 200 Pa 
     The processing conditions shown here are the conditions under which the MS gas is thermally decomposed in the process chamber  201  when the MS gas exists alone, i.e., the conditions under which a CVD reaction occurs. That is, the processing conditions shown here are the conditions under which no self-limit is imposed on adsorption (deposition) of Si on the wafer  200 , i.e., the conditions under which the adsorption of Si on the wafer  200  is not self-limited. 
     As the first processing gas, in addition to the MS gas, it may be possible to use the various kinds of silicon hydride gases described above and the various kinds of the halosilane-based gases described above. In order to suppress the remaining of a halogen element in the Si film, it is preferable to use a silicon hydride gas as the first processing gas. In order to improve the deposition rate of the Si film, it is preferable to use a highly-reactive halosilane-based gas as the first processing gas. 
     As the dopant gas, in addition to the PH gas, it may be possible to use a gas such as an arsine (AsH 3 ) gas or the like containing an element (P, arsenic (As) or the like) which is a Group V element and which becomes solid by itself. Furthermore, as the dopant gas, in addition to the gas containing a Group V element, it may be possible to use a gas such as a diborane (B 2 H 6 ) gas, a trichloroborane (BCl 3 ) gas or the like containing an element (boron (B) or the like) which is a Group III element and which becomes solid by itself. 
     (After-Purging and Atmospheric Pressure Restoration) 
     After the Si film formation step is completed, the N 2  gas as a purge gas is supplied from the nozzles  249   a  to  249   c  into the process chamber  201  and is exhausted from the exhaust port  231   a . As a result, the interior of the process chamber  201  is purged and the gas or the reaction byproduct remaining in the process chamber  201  is removed from the process chamber  201  (after-purging). Thereafter, the atmosphere in the process chamber  201  is replaced with an inert gas (inert gas replacement), and the pressure in the process chamber  201  is restored to the atmospheric pressure (atmospheric pressure restoration). 
     (Boat Unloading and Wafer Discharging) 
     The seal cap  219  is lowered by the boat elevator  115  and the lower end opening of the manifold  209  is opened. Then, the processed wafers  200  are unloaded from the lower end of the manifold  209  to the outside of the reaction tube  203  in a state in which they are supported by the boat  217  (boat unloading). After the boat unloading, the shutter  219   s  is moved so that the lower end opening of the manifold  209  is sealed by the shutter  219   s  via the O-ring  220   c  (shutter closing). The processed wafers  200  are taken out from the boat  217  after they are unloaded to the outside of the reaction tube  203  (wafer discharging). 
     (3) Effects of the Present Embodiment 
     According to the present embodiment, one or more of the following effects may be obtained. 
     (a) When supplying the MS gas from the nozzle  249   c  in the Si film formation step, by controlling the balance between the flow rate of the N 2  gas supplied from the nozzle  249   a  and the flow rate of the N 2  gas supplied from the nozzle  249   b , it is possible to adjust the in-plane film thickness distribution of the Si film formed on the wafer  200 . For example, it is possible to set the in-plane film thickness distribution of the Si film formed on the wafer  200  configured as a bare wafer to become a center convex distribution. Thus, when a pattern wafer is used as the wafer  200 , it is possible to form a Si film having a flat distribution on the wafer  200 . 
     Although the in-plane film thickness distribution of the film formed on the wafer  200  depends on the surface area of the wafer  200 , it is considered that this is due to the so-called loading effect. When a precursor such as an MS gas or the like flows from the outer peripheral portion to the central portion of the wafer  200  as in the substrate processing apparatus according to the present embodiment, as the surface area of the wafer  200  subjected to film formation becomes larger, the precursor such as the MS gas or the like is consumed in a large amount at the outer peripheral portion of the wafer  200 , and thus it becomes hard for the precursor to reach the central portion of the wafer  200 . As a result, the in-plane film thickness distribution of the film formed on the wafer  200  tends to become a center concave distribution. According to the present embodiment, even when a pattern wafer having a large surface area is used as the wafer  200 , it is possible to correct the in-plane film thickness distribution of the film formed on the wafer  200  from a center concave distribution to a flat distribution, ultimately to a center convex distribution. This makes it possible to freely control the in-plane film thickness distribution of the film formed on the wafer  200 . 
     (b) In the Si film formation step, by supplying the N 2  gas using the two nozzles  249   a  and  249   b , as compared with a case where the N 2  gas is supplied using one nozzle, it is possible to precisely and widely adjust the in-plane film thickness distribution of the Si film to be formed on the wafer  200 . This is because, according to the method of the present embodiment, it is possible to individually, i.e., independently, control the concentration (supply amount) of the MS gas or the like supplied to the central portion of the wafer  200  and the concentration (supply amount) of the MS gas or the like supplied to the outer peripheral portion of the wafer  200 .
 
(c) By disposing at least the nozzle  249   b , preferably the nozzles  249   a  to  249   c  so as to be opposed to the exhaust port  231   a  at least in a plan view, it is possible to enhance the controllability of the in-plane film thickness distribution of the Si film formed on the wafer  200 . Further, by arranging the nozzles  249   a  and  249   c  line-symmetrically with respect to the straight line L as a symmetry axis, it becomes possible to further enhance the controllability of the in-plane film thickness distribution of the Si film formed on the wafer  200 .
 
(d) By performing the seed layer formation step after preparing the wafer  200  and before performing the Si film formation step, it is possible to shorten the incubation time (growth delay) of the Si film formed on the wafer  200 , thereby improving the productivity of the film-forming process.
 
(e) In the seed layer formation step, by alternately performing the supply of the DCS gas and the supply of the DS gas, it is possible to enhance the formation efficiency of the seed layer and to make the seed layer dense. This makes it possible to enhance the productivity of the film-forming process and to make the Si film formed on the wafer  200  dense. In addition, by alternately supplying the gases, it is possible to suppress excess gas phase reaction in the process chamber  201  and to improve the quality of the film-forming process.
 
(f) The aforementioned effects may be similarly obtained even when using the first processing gas other than the MS gas, using the second processing gas other than the DS gas, using the third processing gas other than the DCS gas, using the dopant gas other than PH gas, and using the inert gas other than the N 2  gas.
 
     (4) Modification 
     The film formation step according to the present embodiment is not limited to the embodiment shown in  FIG. 4 , but may be changed as in the following modifications. These modifications may be arbitrarily combined. Unless specifically mentioned otherwise, the processing procedures and processing conditions in each step of each of the modifications may be the same as the processing procedures and processing conditions in each step of the above-described substrate processing sequence. 
     (Modification 1) 
     In the film formation sequence shown in  FIG. 4 , there has been described an example where the seed layer formation step is performed. However, the seed layer formation step may not be performed. Even in this modification, when the MS gas is supplied from the nozzle  249   c  in the Si film formation step, by controlling the balance between the flow rate of the N 2  gas supplied from the nozzle  249   a  and the flow rate of the N 2  gas supplied from the nozzle  249   b , it becomes possible to adjust the in-plane film thickness distribution of the Si film formed on the wafer  200 . 
     (Modification 2) 
     In the Si film formation step, when the MS gas or the like is supplied from the nozzle  249   c , the flow rate of the N 2  gas supplied from the nozzle  249   a  may be smaller than the flow rate of the N 2  gas supplied from the nozzle  249   b . In this case, for example, the flow rate of the N 2  gas supplied from the nozzle  249   a  is set to 10 to 400 sccm and the flow rate of the N 2  gas supplied from the nozzle  249   b  is set to 500 to 2000 sccm. By controlling the flow rate balance in this manner, it is possible to control the concentration (supply amount) of the MS gas or the like supplied to the central portion of the wafer  200  in a decreasing direction and to control the concentration (supply amount) of the gas or the like supplied to the outer peripheral portion of the wafer  200  in an increasing direction. As a result, it becomes possible to bring the in-plane film thickness distribution of the Si film formed on the wafer  200  closer to a flat distribution, ultimately to a center concave distribution from a center convex distribution. 
     In the case where the in-plane film thickness distribution of the Si film formed on the wafer  200  becomes a desired distribution, when the MS gas or the like is supplied from the nozzle  249   c , the flow rate of the N 2  gas supplied from the nozzle  249   a  and the flow rate the N 2  gas supplied from the nozzle  249   b  may be made equal to each other without making them different. 
     (Modification 3) 
     In step 2 of the seed layer formation step as well as the Si film formation step, when the DS gas is supplied from the nozzle  249   a , it may be possible to control the balance between the flow rate of the N 2  gas supplied from the nozzle  249   b  and the flow rate of the N 2  gas supplied from the nozzle  249   c . For example, the in-plane thickness distribution of the seed layer formed on the wafer  200  may be adjusted by making the flow rate of the N 2  gas supplied from the nozzle  249   b  different from the flow rate of the N 2  gas supplied from the nozzle  249   c . As a result, it becomes possible to adjust the in-plane film thickness distribution of the Si film formed on the wafer  200 . 
     For example, when the DS gas is supplied from the nozzle  249   a , the flow rate of the N 2  gas supplied from the nozzle  249   b  may be smaller than the flow rate of the N 2  gas supplied from the nozzle  249   c . In this case, for example, the flow rate of the N 2  gas supplied from the nozzle  249   b  is set to 10 to 400 sccm and the flow rate of the N 2  gas supplied from the nozzle  249   c  is set to 500 to 2000 sccm. By controlling the flow rate balance in this manner, it is possible to bring the in-plane thickness distribution of the seed layer formed on the wafer  200  closer to a flat distribution, ultimately to a center convex distribution from a center concave distribution. 
     Moreover, for example, when the DS gas is supplied from the nozzle  249   a , the flow rate of the N 2  gas supplied from the nozzle  249   b  may be larger than the flow rate of the N 2  gas supplied from the nozzle  249   c . In this case, for example, the flow rate of the N 2  gas supplied from the nozzle  249   b  is set to 500 to 2000 sccm and the flow rate of the N 2  gas supplied from the nozzle  249   c  is set to 10 to 400 sccm. By controlling the flow rate balance in this manner, it is possible to bring the in-plane thickness distribution of the seed layer formed on the wafer  200  closer to a flat distribution, ultimately to a center concave distribution from a center convex distribution. 
     (Modification 4) 
     In step 2 of the seed layer formation step, the N 2  gas may be supplied from the nozzle  249   a  to the wafer  200 , the N 2  gas may be supplied from the nozzle  249   b  to the wafer  200 , and the DS gas may be supplied from the nozzle  249   c  to the wafer  200 . That is, in the Si film formation step and step 2 of the seed layer formation step, the processing gases (the DS gas and the MS gas) may be supplied from the common nozzle  249   c.    
     In this case, in step 2, when the DS gas is supplied from the nozzle  249   c , by controlling the balance between the flow rate of the N 2  gas supplied from the nozzle  249   a  and the flow rate of the N 2  gas supplied from the nozzle  249   b , it is possible to adjust the in-plane thickness distribution of the seed layer formed on the wafer  200 . In this case, the supply conditions of the N 2  gas supplied from each of the nozzles  249   a  and  249   b  can be the same as those in the Si film formation step. 
     For example, when the DS gas is supplied from the nozzle  249   c , by making the flow rate of the N 2  gas supplied from the nozzle  249   a  larger than the flow rate of the N 2  gas supplied from the nozzle  249   b , it becomes possible to bring the in-plane thickness distribution of the seed layer formed on the wafer  200  closer to a flat distribution, ultimately to a center convex distribution from a center concave distribution. As a result, it is possible to adjust the in-plane film thickness distribution of the Si film formed on the wafer  200 . 
     Furthermore, for example, when the DS gas is supplied from the nozzle  249   c , by making the flow rate of the N 2  gas supplied from the nozzle  249   a  smaller than the flow rate of the N 2  gas supplied from the nozzle  249   b , it becomes possible to bring the in-plane thickness distribution of the seed layer formed on the wafer  200  closer to a flat distribution, ultimately to a center concave distribution from a center convex distribution. As a result, it is possible to adjust the in-plane film thickness distribution of the Si film formed on the wafer  200 . 
     (Modification 5) 
     In step 1 of the seed layer formation step, the DCS gas may be supplied to the wafer  200  from any of the nozzles  249   a  and  249   c.    
     In step 1, when supplying the DCS gas from the nozzle  249   c , it may be possible to control the balance between the flow rate of the N 2  gas supplied from the nozzle  249   a  and the flow rate of the N 2  gas supplied from the nozzle  249   b . For example, by making the flow rate of the N 2  gas supplied from the nozzle  249   a  different from the flow rate of the N 2  gas supplied from the nozzle  249   b , it is possible to make the degree of cleaning performed on the surface of the wafer  200  different in the plane of the wafer  200 . Thus, it is possible to adjust the in-plane thickness distribution of the seed layer formed on the wafer  200 . As a result, it is possible to adjust the in-plane film thickness distribution of the Si film formed on the wafer  200 . 
     For example, when supplying the DCS gas from the nozzle  249   c , by making the flow rate of the N 2  gas supplied from the nozzle  249   a  larger than the flow rate of the N 2  gas supplied from the nozzle  249   b , the cleaning action at the central portion of the wafer  200  may be controlled in an increasing direction and the cleaning action at the outer peripheral portion of the wafer  200  may be controlled in a decreasing direction. This makes it possible to bring the in-plane thickness distribution of the seed layer formed on the wafer  200 , i.e., the in-plane film thickness distribution of the Si film formed on the wafer  200  closer to a flat distribution, ultimately to a center convex distribution from a center concave distribution. 
     Furthermore, for example, when supplying the DCS gas from the nozzle  249   c , by making the flow rate of the N 2  gas supplied from the nozzle  249   a  smaller than the flow rate of the N 2  gas supplied from the nozzle  249   b , the cleaning action at the central portion of the wafer  200  may be controlled in a decreasing direction and the cleaning action at the outer peripheral portion of the wafer  200  may be controlled in an increasing direction. This makes it possible to bring the in-plane thickness distribution of the seed layer formed on the wafer  200 , i.e., the in-plane film thickness distribution of the Si film formed on the wafer  200  closer to a flat distribution, ultimately to a center concave distribution from a center convex distribution. 
     When supplying the DCS gas from the nozzle  249   a  in step 1, by controlling the balance between the flow rate of the N 2  gas supplied from the nozzle  249   b  and the flow rate of the N 2  gas supplied from the nozzle  249   c , it is possible to obtain the same effects. 
     (Modification 6) 
     In modifications 3 to 5, the flow rate balance control for the N 2  gas in the Si film formation step may not be performed. Even in this case, it is possible to adjust the in-plane film thickness distribution of the Si film formed on the wafer  200  to some extent by adjusting the in-plane thickness distribution of the seed layer formed on the wafer  200 . 
     (Modification 7) 
     As in the film formation sequence shown below, in the seed layer formation step, step 1 may not be performed and step 2 may be performed a predetermined number of times (one or more times). Furthermore, in step 2, as the second processing gas, in addition to the silicon hydride gas, it may be possible to use an aminosilane-based gas such as a tetrakisdimethylaminosilane (Si[N(CH 3 ) 2 ] 4 , abbreviation: 4DMAS) gas, a trisdimethylaminosilane (Si[N(CH 3 ) 2 ] 3 H, abbreviation: 3DMAS) gas, a bisdiethylaminosilane (Si[N(C 2 H 5 ) 2 ] 2 H 2 , abbreviation: BDEAS) gas, a bis-tertiary-butylaminosilane (SiH 2 [NH (C 4 H 9 )] 2 , abbreviation: BTBAS) gas, a diisopropylaminosilane (SiH 3 N[CH(CH 3 ) 2 ] 2 , abbreviation: DIPAS) gas or the like.
 
DIPAS→MS+PH⇒P-doped Si
 
(Modification 8)
 
     As in the film formation sequence shown below, in the seed layer formation step, each of steps 1 and 2 may be performed once. In addition, in step 1, in addition to the halosilane-based gas, an Si-free halogen-based gas such as an HCl gas or the like may be used as the third processing gas.
 
HCl→DS→MS+PH⇒P-doped Si
 
(Modification 9)
 
     As the first processing gas, in addition to the silicon hydride gas, it may be possible to use, for example, a chlorosilane-based gas such as a DCS gas, an HCDS gas or the like, or an aminosilane-based gas such as a 3DMAS gas, a BDEAS gas or the like. 
     In addition to the above-described processing gases, as a reactant, it may be possible to additionally use, for example, an amine-based gas such as a triethylamine ((C 2 H 5 ) 3 N, abbreviation: TEA) gas or the like, an oxygen (O)-containing gas (oxidizing agent) such as an oxygen (O 2 ) gas, a water vapor (H 2 O gas), an ozone ( 0   3 ) gas, a plasma-excited O 2  gas (O 2 *), a mixture of an O 2  gas and a hydrogen (H 2 ) gas or the like, a carbon (C)-containing gas such as a propylene (C 3 H 6 ) gas or the like, and a B-containing gas such as a BCl 3  gas or the like. 
     For example, according to the film formation sequences shown below, a silicon nitride film (Si film), a silicon oxynitride film (SiON film), a silicon oxycarbide film (SiOC film), a silicon carbonitride film (SiCN film), a silicon oxycarbonitride film (SiOCN film), a silicon borocarbonitride film (SiBCN film), a silicon boronitride film (SiBN film), and a silicon oxide film (SiO film) may be formed on the wafer  200 . In the following film formation sequences, when supplying the first processing gas (the DCS gas, the HCDS gas, the 3DMAS gas or the BDEAS gas) from the nozzle  249   c , the balance of the flow rates of the N 2  gases supplied from the nozzles  249   a  and  249   b  is controlled in the same manner as in the film formation sequence shown in  FIG. 4  or the modification described above. Thus, the same effects as those of the film formation sequence shown in  FIG. 4  or the above-described modifications are obtained.
 
DCS+NH 3 ⇒SiN
 
(DCS→NH 3 )× n ⇒SiN
 
(HCDS→NH 3 →O 2 )× n ⇒SiON
 
(HCDS→TEA→O 2 )× n ⇒SiOC(N)
 
(HCDS→C 3 H 6 →NH 3 )× n ⇒SiCN
 
(HCDS→C 3 H 6 →NH 3 →O 2 )× n ⇒SiOCN
 
(HCDS→C 3 H 6 →BCl 3 →NH 3 )× n ⇒SiBCN
 
(HCDS→BCl 3 →NH 3 )× n ⇒SiBN
 
(HCDS→O 2 +H 2 )× n ⇒SiO
 
(3DMAS→O 3 )× n ⇒SiO
 
(BDEAS→O 2 *)× n ⇒SiO
 
     An example of processing conditions in the step of supplying the first processing gas in this modification is described as follows.
         First processing gas supply flow rate: 10 to 2000 sccm   First processing gas supply time: 1 to 120 seconds   Processing temperature: 250-800 degrees C.   Processing pressure: 1 to 2666 Pa   Other processing conditions are the same as the processing conditions in the Si film formation step of the film formation sequence shown in  FIG. 4 .       

     An example of processing conditions in the step of supplying the reactant is described as follows.
         Reactant supply flow rate: 100 to 10000 sccm   Reactant supply time: 1 to 120 seconds   Processing pressure: 1 to 4000 Pa   Other processing conditions are the same as the processing conditions in the step of supplying the first processing gas in this modification.       

     Even in this modification, the seed layer formation step may be performed on the wafer  200  after preparing the wafer  200  and before performing the film formation sequence described above. 
     Other Embodiments 
     The embodiment of the present disclosure has been concretely described above. However, the present disclosure is not limited to the above-described embodiment. Various modifications may be made without departing from the spirit of the present disclosure. 
     In the above-described embodiment, there has been described an example where the nozzles  249   a  to  249   c  are installed adjacent to each other (in close proximity with each other). However, the present disclosure is not limited to such embodiments. For example, the nozzles  249   a  and  249   c  may be installed at the positions away from the nozzle  249   b  in the annular space in a plan view between the inner wall of the reaction tube  203  and the wafers  200 . 
     In the above-described embodiment, there has been described an example where the first to third suppliers are composed of the nozzles  249   a  to  249   c  and the three nozzles are installed in the process chamber  201 . However, the present disclosure is not limited to such embodiments. For example, at least one selected from the group of the first to third suppliers may be composed of two or more nozzles. Further, a nozzle other than the first to third suppliers may be newly installed in the process chamber  201 , and an N 2  gas or various processing gases may be further supplied using this nozzle. When the nozzle other than the nozzles  249   a  to  249   c  is installed in the process chamber  201 , the newly installed nozzle may be installed at a position facing the exhaust port  231   a  in a plan view or may be installed at a position not facing the exhaust port  231   a . That is, the newly installed nozzle may be located at a position spaced apart from the nozzles  249   a  to  249   c , for example, an intermediate position between the nozzles  249   a  to  249   c  and the exhaust port  231   a  or a position near the intermediate position along the outer peripheries of the wafers  200  in the annular space in a plan view between the inner wall of the reaction tube  203  and the wafers  200 . 
     In the above-described embodiment, there has been described an example where the film containing Si as a main element is formed on the substrate. However, the present disclosure is not limited to such embodiments. That is, the present disclosure may be suitably applied to a case where a film not containing Si but containing a semimetal element such as germanium (Ge), B or the like as a main element is formed on the substrate. The present disclosure may also be suitably applied to a case where a film containing a metal element such as titanium (Ti), zirconium (Zr), hafnium (Hf), niobium (Nb), tantalum (Ta), molybdenum (Mo), tungsten (W), yttrium (Y), lanthan (La), strontium (Sr), aluminum (Al) or the like as a main element is formed on the substrate. 
     It is preferable that the recipes used for substrate processing are individually prepared according to the processing contents and stored in the memory device  121   c  via the electric communication line or the external memory device  123 . When starting a process, it is preferable that the CPU  121   a  appropriately selects an appropriate recipe from the plurality of recipes stored in the memory device  121   c  according to the substrate processing contents. This makes it possible to form films of various film types, composition ratios, film qualities and film thicknesses with high reproducibility in one substrate processing apparatus. It is also possible to reduce the burden on an operator and to quickly start the process while avoiding operation errors. 
     The above-described recipes are not limited to the case of newly creating them, but may be prepared by, for example, changing the existing recipes already installed in the substrate processing apparatus. In the case of changing the recipes, the changed recipes may be installed in the substrate processing apparatus via an electric communication line or a recording medium in which the recipes are recorded. In addition, by operating the input/output device  122  installed in the existing substrate processing apparatus, the existing recipes already installed in the substrate processing apparatus may be directly changed. 
     In the above-described embodiment, there has been described an example where the first to third suppliers are installed in the process chamber so as to extend along the inner wall of the reaction tube. However, the present disclosure is not limited to the embodiments described above. For example, as can be noted from the cross-sectional structure of the vertical process furnace shown in  FIG. 5A , a buffer chamber may be installed in the side wall of the reaction tube, and in the buffer chamber, first to third suppliers having the same configuration as in the above-described embodiment may be installed in the same arrangement as in the above-described embodiment. In  FIG. 5A , there is shown an example where a supply-purpose buffer chamber and an exhaust-purpose buffer chamber are installed in the side wall of the reaction tube and are disposed at positions facing each other across the wafers. Each of the supply-purpose buffer chamber and the exhaust-purpose buffer chamber is installed to extend from the lower portion to the upper portion of the side wall of the reaction tube, i.e., along the wafer arrangement region. In addition,  FIG. 5A  shows an example where the supply-purpose buffer chamber is partitioned into a plurality of (three) spaces, and individual nozzles are disposed in the respective spaces. The arrangement of the three spaces of the buffer chamber is the same as the arrangement of the first to third suppliers. Furthermore, for example, as can be noted from the cross-sectional structure of the vertical process furnace shown in  FIG. 5B , a buffer chamber may be installed in the same arrangement as in  FIG. 5A , a second supplier may be installed in the buffer chamber, and first and third suppliers may be installed so as to sandwich the communication portion, which communicates with the process chamber, of the buffer chamber from both sides of the communication portion and so as to extend along the inner wall of the reaction tube. The configurations other than the buffer chamber and the reaction tube described with reference to  FIGS. 5A and 5B  are the same as the configurations of the respective parts of the process furnace shown in  FIG. 1 . Even when these process furnaces are used, the same effects as those of the above-described embodiment are obtained. 
     In the above-described embodiment, there has been described an example where a film is formed using a batch type substrate processing apparatus that processes a plurality of substrates at a time. The present disclosure is not limited to the above-described embodiments, but may be suitably applied to, for example, a case where a film is formed using a single-wafer type substrate processing apparatus that processes one or plural substrates at a time. Furthermore, in the above-described embodiment, there has been described an example where a film is formed using a substrate processing apparatus including a hot wall type process furnace. The present disclosure is not limited to the above-described embodiments, but may be suitably applied to a case where a film is formed using a substrate processing apparatus including a cold wall type process furnace. 
     Even in the case of using these substrate processing apparatuses, film formation can be performed under the same sequences and processing conditions as those of the above-described embodiment and modifications, and the same effects as described above are obtained. 
     Further, the above-described embodiment and modifications may be used in combination as appropriate. The processing procedures and processing conditions at this time may be the same as, for example, the processing procedures and processing conditions of the above-described embodiment. 
     The various effects described in this specification are similarly obtained not only when the formation of a film on a substrate is performed under the conditions that the processing gas supplied to the substrate is thermally decomposed (under the conditions that a self-limit is not applied) but also when the formation of a film on a substrate is performed under the conditions that the processing gas supplied to the substrate is not thermally decomposed (under the conditions that a self-limit is applied). However, the effect relating to the adjustment of the in-plane film thickness distribution among the various effects described above is particularly effectively obtained when the formation of a film on a substrate is performed under the conditions that the processing gas supplied to the substrate is thermally decomposed and the CVD reaction occurs. 
     [Example] 
     In sample A, using the substrate processing apparatus shown in  FIG. 1 , a Si film was formed on the wafer according to the film formation sequence shown in  FIG. 4 . When performing the Si film formation step, the flow rate of the N 2  gas supplied from the first supplier was set to a predetermined flow rate within a range of 150 to 250 sccm and the flow rate of the N 2  gas supplied from the second supplier was set to a predetermined flow rate within a range of 40 to 80 sccm. Other processing conditions were set to predetermined conditions falling within the processing condition range described in the above embodiment. 
     In sample B, using the substrate processing apparatus shown in  FIG. 1 , a Si film was formed on the wafer according to the film formation sequence shown in  FIG. 4 . When performing the Si film formation step, the flow rate of the N 2  gas supplied from the first supplier was set to a predetermined flow rate within a range of 450 to 550 sccm and the flow rate of the N 2  gas supplied from the second supplier was set to a predetermined flow rate within a range of 40 to 80 sccm. Other processing conditions were the same as the processing conditions used when preparing sample A. 
     In sample C, using the substrate processing apparatus shown in  FIG. 1 , a Si film was formed on the wafer according to the film formation sequence shown in  FIG. 4 . However, when performing the Si film formation step, the balance of the flow rates of the N 2  gases supplied from the first and second suppliers was reversed from that at the time of preparing sample A. Specifically, when performing the Si film formation step, the flow rate of the N 2  gas supplied from the first supplier was set to a predetermined flow rate within a range of 250 to 350 sccm and the flow rate of the N 2  gas supplied from the second supplier was set to a predetermined flow rate within a range of 700 to 900 sccm. Other processing conditions were the same as the processing conditions used when preparing sample A. 
     Then, the film thicknesses of the Si films of samples A to C were measured at the outer peripheral portion of the wafer and compared with each other.  FIG. 6A  is a diagram for comparing the measurement results of samples A and B, and  FIG. 6B  is a diagram for comparing the measurement results of samples A and C. The measurement positions (the distances from the center of the wafer) of samples A and B in  FIG. 6A  are positions corresponding to each other, and the measurement positions (the distances from the center of the wafer) of samples A and C in  FIG. 6B  are also positions corresponding to each other. However, the measurement positions of samples A and B in  FIG. 6A  and the measurement positions of samples A and C in  FIG. 6B  are different positions in the outer peripheral portion of the wafer. Each of the vertical axes in  FIGS. 6A and 6B  indicates a film thickness (A), the horizontal axis in  FIG. 6A  indicates samples A and B, and the horizontal axis in  FIG. 6B  indicates samples A and C. 
     According to  FIG. 6A , it can be seen that the film thickness of the Si film of sample B at the outer peripheral portion of the wafer is smaller than the film thickness of the Si film of sample A at the outer peripheral portion of the wafer. That is, when performing the Si film formation step, by increasing the flow rate of the N 2  gas supplied from the first supplier, i.e., by increasing the ratio of the flow rate of the N 2  gas supplied from the first supplier to the flow rate of the N 2  gas supplied from the second supplier, it is possible to adjust the film thickness of the Si film formed on the outer peripheral portion of the wafer in a decreasing direction. 
     Further, according to  FIG. 6B , it can be seen that the film thickness of the Si film of sample B at the outer peripheral portion of the wafer is larger than the film thickness of the Si film of sample A at the outer peripheral portion of the wafer. That is, when performing the Si film formation step, by reversing the flow rate balance so as to make the flow rate of the N 2  gas supplied from the second supplier larger than the flow rate of the N 2  gas supplied from the first supplier, it is possible to adjust the film thickness of the Si film formed on the outer peripheral portion of the wafer in an increasing direction. 
     From these results, it can be noted that, when performing the Si film formation step, by controlling the balance between the flow rate of the N 2  gas supplied from the first supplier and the flow rate of the N 2  gas supplied from the second supplier, it is possible to adjust the in-plane film thickness distribution of the Si film formed on the wafer over a wide range and in a precise manner. 
     According to the present disclosure in some embodiments, it is possible to control the substrate in-plane film thickness distribution of a film formed on a 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.