Patent Publication Number: US-2013251896-A1

Title: Method of protecting component of film forming apparatus and film forming method

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Japanese Patent Application No. 2012-067573 filed on Mar. 23, 2012, in the Japan Patent Office, the disclosure of which is incorporated herein in its entirety by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a method of protecting components of a film forming apparatus and a film forming method. 
     BACKGROUND 
     In manufacturing semiconductor integrated circuit devices, a film forming apparatus is used for forming a thin film. The film forming apparatus deposits, for example, silicon, silicon oxide, silicon nitride or the like on a semiconductor wafer that is a target substrate to be processed, and forms a silicon film, a silicon oxide film, a silicon nitride film or the like on the semiconductor wafer. 
     However, such a deposition does not occur only on the semiconductor wafer, but on an inner surface of a processing chamber or surfaces of components arranged within the processing chamber such as a processing gas inlet tube and the like. For this reason, after performing the film forming processing several times, a so-called cleaning process has to be performed to remove the thin films deposited on the inner surface of the processing chamber or the components such as the processing gas inlet tube and the like. 
     As described above, the thin films deposited on the components are cleaned and removed after the film forming process is performed several times. 
     However, the thin film subjects the components to a strong stress. For example, in case of components made of quartz, the component is subjected to a strong tensile stress when silicon nitride is deposited on the component. If the deposition of silicon nitride accumulates, the component is more likely have fine cracks, and finally, a superficial layer portion of the component could be thinly delaminated and then fall off. 
     As described above, a component which is finely cracked or has a portion that has a superficial layer of damage which could be thinly delaminated may be a source of unwanted particles. 
     SUMMARY 
     The present disclosure provides a component protection method of a film forming apparatus capable of suppressing damage of a component of the film forming apparatus even though a thin film has been deposited on the component, and a film forming method including the component protection method. 
     According to a first aspect of the present disclosure, provided is a component protection method of protecting a component of a film forming apparatus, the method comprising forming a film having a rough surface on a surface of a component of a film forming apparatus such that the surface of the component is coated with the film having the rough surface, before or after film forming processing on a target substrate in the interior of a processing chamber of a film forming apparatus, and the component being located in the interior of the processing chamber and exposed to a film forming atmosphere during the film forming processing on the target substrate. 
     According to a second aspect of the present disclosure, provided is a film forming method of performing film forming processing on a target substrate, the method comprising carrying the target substrate into an interior of a processing chamber of a film forming apparatus, the target substrate being loaded in a substrate loading jig; performing film forming processing on the target substrate in the interior of the processing chamber; and forming a film having a rough surface on a surface of a component of a film forming apparatus such that the surface of the component is coated with the film having the rough surface, before film forming processing on a Target substrate, or after the film forming processing on the target substrate, or both before and after the film forming processing on the target substrate, and the component being located in the interior of the processing chamber and exposed to a film forming atmosphere during the film forming processing on the target substrate. 
    
    
     
       BRIEF DESCRIPTION OF THE 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 showing an example of a film forming apparatus to which a component protection method according to an embodiment of the present disclosure may be applied; 
         FIG. 2  is a transverse sectional view of the film forming apparatus shown in  FIG. 1 ; 
         FIG. 3  is a flow chart illustrating an example of a component protection method according to a first embodiment of the present disclosure; 
         FIGS. 4A to 4C  are enlarged sectional views schematically showing a portion of a component; 
         FIG. 5  is a flow chart illustrating an example of a component protection method according to a second embodiment of the present disclosure; 
         FIGS. 6A to 6C  are enlarged sectional views schematically showing a portion of a component; 
         FIG. 7  is a view illustrating stress on a silicon nitride film; 
         FIG. 8  is a flow chart illustrating an example of a component protection method according to a third embodiment of the present disclosure; and 
         FIG. 9  is a flow chart illustrating an example of a component protection method according to a fourth embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In addition, throughout the drawings, like reference numerals are used to designate like elements. 
     &lt;Film Forming Apparatus&gt; 
     First of all, an example of a film forming apparatus, to which a component protection method according to an embodiment of the present disclosure may be applied, will be described. 
       FIG. 1  is a longitudinal sectional view showing an example of a film forming apparatus to which a component protection method according to an embodiment of the present disclosure may be applied; and  FIG. 2  is a transverse sectional view of the film forming apparatus shown in  FIG. 1 . 
       FIG. 1  shows a batch type film forming apparatus  100  for forming a silicon nitride film on a semiconductor wafer (silicon substrate) W, which is a target substrate to be processed, using an ALD (Atomic Layered Deposition) method, as an example of a film forming apparatus to which a component protection method according to an embodiment of the present disclosure may be applied. 
     As shown in  FIG. 1 , the film forming apparatus  100  includes a cylindrical processing chamber  101  having an open lower end and a ceiling. The processing chamber  101  is entirely formed, for example, of quartz. A quartz ceiling plate  102  is located at the ceiling of the processing chamber  101  and makes acts as a seal. In addition, a manifold  103 , which, for example, is formed of stainless steel in the shape of a cylinder, is connected to the opening of the lower end of the processing chamber  101  through a sealing member  104  such as an O-ring. 
     The manifold  103  supports the lower end of the processing chamber  101 . A wafer boat  105  made of quartz, to which plural sheets, for example, 50 to 100 sheets of semiconductor wafers W can be loaded in a multistage manner, can be carried into or out of the processing chamber  101  from the bottom of the manifold  103 . The wafer boat  105 , which is a substrate loading jig configured to load a target substrate to be processed, has, for example, three pillars  106  (see  FIG. 2 ), and allows plural sheets of wafers W to be supported by means of grooves (not shown) formed in the pillars  106 . 
     The wafer boat  105  is loaded on a table  108  through a thermal insulation container  107  made of quartz. The table  108  is supported on a rotating shaft  110 , which penetrates a lid portion  109  opening and closing a lower end of the manifold  103 , for example, the lid portion  109  is made of stainless steel. 
     In addition, the portion penetrated by the rotating shaft  110 , for example, is fitted with a magnetic fluid seal  111  and airtightly seals and supports the rotating shaft  110  to be rotatable. Also, a sealing member  112  such as an O-ring is interposed and installed between a periphery of the lid portion  109  and the lower end of the manifold  103 , thereby maintaining the processing chamber  101  to be sealed. 
     The rotating shaft  110  is mounted to a leading end of an arm  113  supported by a lift unit (not shown) such as a boat elevator and is configured to lift up or down the wafer boat  105 , the lid portion  109 , and the like together so that they can be inserted into or be separated from the processing chamber  101 . In addition, the table  108  may be fixedly installed to the lid portion  109 , and thus, the wafers W may be processed without rotating the wafer boat  105 . 
     The film forming apparatus  100  is provided with a nitriding agent-containing gas supply unit  114 , a silicon source gas supply unit  115 , and an inert gas supply unit  116 . The nitriding agent-containing gas supply unit  114  feeds a nitriding agent-containing gas into the processing chamber  101 . The silicon source gas supply unit  115  also feeds a silicon source gas into the processing chamber  101 . The inert gas supply unit  116  also feeds an inert gas into the processing chamber  101 . The inert gas is used, for example, as a purge gas and a dilution gas within the processing chamber  101 . 
     The nitriding agent-containing gas may include, for example, ammonia (NH 3 )-containing gas, nitrogen oxide (NO)-containing gas, ammonia and nitrogen oxide-containing gas, and the like. The silicon source gas may include, for example, silane-based gas, such as monosilane (SiH 4 ), disilane (Si 2 H 6 ), or dichlorosilane (DCS:SiH 2 Cl 2 ). 
     In addition, a plurality of silicon source gases are prepared in the silicon source gas supply unit  115 , and at least one of the prepared silicon source gases may be selected to be fed into the processing chamber  101 . The inert gas includes, for example, nitrogen gas (N 2  gas), argon gas (Ar gas), and the like. 
     The nitriding agent-containing gas supply unit  114  is configure to includes a nitriding agent-containing gas supply source  118   a,  a nitriding agent-containing gas supply line  119   a  for inducing a nitriding agent-containing gas from the nitriding agent-containing gas supply source  118   a,  an opening and closing valve  122   a  and a flow controller  123   a  which are installed in the middle of the nitriding agent-containing gas supply line  119   a.    
     The silicon source gas supply unit  115  is configured to include a silicon source gas supply source  118   b,  a silicon source gas supply line  119   b  for inducing a silicon source gas from the silicon source gas supply source  118   b,  an opening and closing valve  122   b  and a flow controller  123   b  which are installed in the middle of the silicon source gas supply line  119   b.    
     The inert gas supply unit  116  is configured to include an inert gas supply source  118   c,  an inert gas supply line  119   c  for inducing an inert gas from the inert gas supply source  118   c,  an opening and closing valve  122   c  and a flow controller  123   c  which are installed in the middle of the inert gas supply line  119   c.    
     The gas inlet tubes such as a nitriding agent-containing gas dispersion nozzle  120   a , silicon source gas dispersion nozzles  120   b  and  120   c,  and an inert gas inlet nozzle  120   d  are arranged in the processing chamber  101  and supply the processing gas into the processing chamber  101 . The nitriding agent-containing gas supply line  119   a  is connected to a nitriding agent-containing gas dispersion nozzle  120   a,  which consists of a quartz tube penetrating a sidewall of the manifold  103  inwards, bent upwards and extending vertically. The silicon source gas supply line  119   b  is also connected to silicon source gas dispersion nozzles  120   b  and  120   c,  each of which consists of a quartz tube penetrating the sidewall of the manifold  103  inwards, bent upwards and extending vertically. Each of the nitriding agent-containing gas dispersion nozzle  120   a  and the silicon source gas dispersion nozzles  120   b  and  120   c  has a plurality of gas injection holes  121   a  to  121   c  formed in the vertical portion thereof to be spaced apart from each other at a predetermined interval (see  FIG. 2  for the gas injection holes  121   c ). In addition, the inert gas supply line  119   c  is connected to an inert gas inlet nozzle  120   d,  which penetrates the sidewall of the manifold  103  inwards. 
     The aforementioned configuration allows the nitriding agent-containing gas, the silicon source gas and the inert gas to be independently supplied into the processing chamber  101  while the flow rate of each gas is independently controlled. 
     A plasma generation unit  124  for generating plasma of the nitriding agent-containing gas is formed on a portion of a sidewall of the processing chamber  101 . The plasma generation unit  124  has a plasma compartment wall  125 . The plasma compartment wall  125  is airtightly connected to an outer wall of the processing chamber  101  in order to cover an opening  101   a  formed in the sidewall of the processing chamber  101 . The opening  101   a  is formed to be vertically elongated by cutting the sidewall of the processing chamber  101  off in the vertical direction to have a predetermined width. This is to uniformly supply plasmas and radicals through the opening  101   a  to all of the wafers W held and supported on the wafer boat  105  in a multistage manner. Further, the plasma compartment wall  125  is formed to have a U-shaped cross section and to be vertically elongated corresponding to the shape of the opening  101   a  and, for example, is made of quartz. The plasma compartment wall  125  is formed on the processing chamber  101 , so that the portion of the sidewall of the processing chamber  101  protrudes outward to be convex and an inner space of the plasma compartment wall  125  is in integral communication with an inner space of the processing chamber  101 . 
     The plasma generation unit  124  is provided with a pair of plasma electrodes  126  (see  FIG. 2 ), a high frequency power supply  127 , and a feed line  128  for feeding high frequency power from the high frequency power supply  127 . The pair of plasma electrodes  126 , each of which is formed to be long and narrow to conform to the shape of the plasma compartment wall  125 , are arranged to face each other on outer surfaces of both sidewalls of the plasma compartment wall  125  along the vertical direction. 
     While extending upward within the processing chamber  101 , the nitriding agent-containing gas dispersion nozzle  120   a  is bent toward the outside of the processing chamber  101  and then erected upward along the innermost portion (the furthermost portion from the center of the processing chamber  101 ) within the plasma compartment wall  125 . Thus, if the high frequency power supply  127  is turned on to generate a high frequency electric field between the pair of plasma electrodes  126 , the nitriding agent-containing gas injected from the gas injection holes  121  a of the nitriding agent-containing gas dispersion nozzle  120   a  is plasma-excited, radicals of the nitriding agent-containing gas are generated, and then, they diffuse and flow toward the center of the processing chamber  101 . For example, if a high frequency voltage of 13.56 MHz is applied from the high frequency power supply  127  to the pair of plasma electrodes  126 , the nitriding agent-containing gas supplied to the space defined by the plasma compartment wall  125  is plasma-excited, and radicals of the nitriding agent-containing gas are generated. For example, if the nitriding agent-containing gas is ammonia, ammonia radicals are generated, and the ammonia radicals react with a silicon source gas or a silicon film in the processing chamber  101 , so that a silicon nitride film can be formed. Also, the frequency of the high frequency voltage is not limited to 13.56 MHz, but the other frequencies, e.g., 400 kHz and the like, may be used. 
     In order to cover the plasma compartment wall  125 , an insulation protection cover  129 , which, for example, is made of quartz, is mounted to the outside of the plasma compartment wall  125 . 
     An evacuation opening  130  for vacuum evacuating the processing chamber  101  is installed to an opposite portion of the opening  101   a  of the processing chamber  101 . The evacuation opening  130  is formed to be narrow and long by cutting off the sidewall of the processing chamber  101  in the vertical direction. An evacuation opening cover member  131 , which is formed to have a U-shaped cross section in order to cover the evacuation opening  130 , is mounted to a portion corresponding to the evacuation opening  130  of the processing chamber  101  by welding. The evacuation opening cover member  131  extends upward along the sidewall of the processing chamber  101  and defines a gas outlet  132  at an upper portion of the processing chamber  101 . An evacuation unit  133 , including a vacuum pump or the like, is connected to the gas outlet  132 . The evacuation unit  133  evacuates the processing chamber  101  to exhaust the processing gas used in the processing and to make the pressure in the processing chamber  101  be a processing pressure required as the processing progresses. 
     A cylindrical heating unit  134  is installed on an outer periphery of the processing chamber  101 . The heating unit  134  activates the gas supplied into the processing chamber  101  and simultaneously heats the wafers W accommodated in the processing chamber  101 . Meanwhile, the heating unit  134  is omitted from being shown in  FIG. 2 . 
     The control of each component of the film forming apparatus  100  is performed, for example, by a process controller  150  consisting of a microprocessor (computer). A user interface  151 , which includes a keyboard or touch panel for input operation of commands and the like for an operator to control the film forming apparatus  100 , a display for visualizing and displaying the operational status of the film forming apparatus  100 , and the like, is connected to the process controller  150 . 
     A memory unit  152  is connected to the process controller  150 . The memory unit  152  stores a control program for implementing various kinds of processing performed in the film forming apparatus  100  by controlling the process controller  150 , or stores a program for performing the processing for the respective components of the film forming apparatus  100  according to processing conditions, i.e., a recipe. The recipe is stored, for example, in a storage medium of the memory unit  152 . The storage medium may be a portable memory, such as a CD-ROM, DVD, or flash memory, as well as a hard disk or semiconductor memory. In addition, the recipe may be suitably transmitted from other units, for example, through a dedicated line. The recipe, if necessary, is read from the memory unit  152  by instructions or the like from the user interface  151  and the processing according to the read recipe is performed by the process controller  150 , so that the processing for forming a silicon nitride film is performed in the film forming apparatus  100  under the control of the process controller  150 . 
     In embodiments of the present disclosure, component protective coatings are formed on components provided in the film forming apparatus  100 . Hereinafter, some embodiments will be described in detail. 
     First Embodiment 
       FIG. 3  is a flow chart illustrating an example of a component protection method according to a first embodiment of the present disclosure; and  FIGS. 4A to 4C  are enlarged sectional views schematically showing a portion of a component. 
     The first embodiment is an example of forming a component protective coating on a surface of a quartz component which is exposed to a film forming atmosphere during the film forming processing, before a silicon nitride film is formed. 
     As shown in operation S 1  of  FIG. 3 , the component protecting processing is performed. In this embodiment, the component protecting processing is performed as follows. 
     First of all, the film forming apparatus  100  in an initial state is prepared (operation S 11 ). Herein, the term “initial state” is a state that film forming processing is not performed directly after the film forming apparatus  100  has finished or a state that film forming processing is not performed directly after the film forming apparatus  100  has cleaned. Then, the wafer boat  105  in an initial state where the wafers W are not loaded is accommodated in the interior of the processing chamber  101  of the film forming apparatus  100  in the initial state (operation S 12 ). 
     Next, the silicon source gas supply unit  115  included in the film forming apparatus  100  is used to form component protective coatings on the surfaces of the quartz components arranged in the interior of the processing chamber  101  (operation S 13 ). In this embodiment, the component protective coating includes a rough surface film having an undulated surface and is made of silicon. Namely, in this embodiment, a silicon film having a rough surface is formed as the component protective coating. Also, the reason why the silicon is selected as the material of the component protective coating is as follows. 
     If a film formed by means of the film forming apparatus  100  is a silicon nitride film, a silicon nitride film is also formed on the surface of the quartz component arranged in the interior of the processing chamber  101 . This silicon nitride film causes the component to be subjected to a strong tensile stress. The silicon film formed on the component as the component protective coating applies a compressive stress to the silicon nitride film and serves to relieve the tensile stress caused by the silicon nitride film. As such, in this embodiment, the silicon film having a stress for canceling the stress generated in the silicon nitride film formed on the quartz component is used as the component protective coating. This is one reason for selecting the silicon film as the component protective coating. Further, the component protective coating can be roughened to relieve the tensile stress caused by the silicon nitride film. 
     In this embodiment, a silicon film having a rough surface is formed as follows. 
     First, a silicon film  2  is formed on the surface of the component (operation S 131 ). An example of a film forming condition when the silicon film  2  is formed is as follows:
         Silicon Source Gas: Monosilane,   Flow Rate of Silicon Source Gas: 300 to 500 sccm,   Processing Time: 3 min,   Processing Temperature: 500 to 600 degrees C., and   Processing Pressure: 13.3 to 26.6 Pa (0.1 to 0.2 Torr).       

     According to this film forming processing, a silicon film  2   a  is formed on a surface of a quartz component  1  arranged in the processing chamber  101  (see  FIG. 4A ). In this embodiment, the surface of the quartz component  1  includes an inner wall surface of the processing chamber  101 , an inner wall surface of the ceiling plate  102 , an outer peripheral surface of the wafer boat  105  including the pillars  106 , an outer peripheral surface of thermal insulation container  107 , an outer peripheral surface of the nitriding agent-containing gas dispersion nozzle  120   a,  outer peripheral surfaces of the silicon source gas dispersion nozzles  120   b  and  120   c,  an outer peripheral surface of the inert gas inlet nozzle  120   d,  and an inner wall surface of the plasma compartment wall  125 . 
     Next, a surface of the silicon film  2   a  is roughened (operation S 132 ). An example of a surface roughening condition when roughening the surface of the silicon film  2   a  is as follows:
         Processing Time: 30 min,   Processing Temperature: 550 to 600 degrees C., and   Processing Pressure: Vacuum.       

     The term “vacuum” in the aforementioned condition means that the evacuation unit  133  is used to continuously evacuate the processing chamber  101  and maintain the internal pressure of the processing chamber  101  at a high degree of vacuum. For example, the internal pressure of the processing chamber  101  is lower than that of forming the silicon film  2   a.    
     The surface roughening processing causes silicon to be agglomerated on the surface of the silicon film  2   a  and the surface of the silicon film  2   a  to be roughened. Accordingly, the silicon film  2  having the rough surface is completed as the component protective coating (see  FIG. 4B ). In this embodiment, each of the inner wall surface of the processing chamber  101 , the inner wall surface of the ceiling plate  102 , the outer peripheral surface of the wafer boat  105  including the pillars  106 , the outer peripheral surface of thermal insulation container  107 , the outer peripheral surface of the nitriding agent-containing gas dispersion nozzle  120   a,  the outer peripheral surfaces of the silicon source gas dispersion nozzles  120   b  and  120   c,  the outer peripheral surface of the inert gas inlet nozzle  120   d,  and the inner wall surface of the plasma compartment wall  125  is coated with the silicon film  2  having the rough surface. Accordingly, the component protecting processing is finished. 
     Thereafter, the film forming apparatus  100  in which the component protecting processing is finished is used to perform the film forming processing (operation S 2 ). To this end, first, the wafer boat  105  having the outer peripheral surface coated with the silicon film  2  having the rough surface is withdrawn from the interior of the processing chamber  101 , and the wafer boat  105  is loaded with the semiconductor wafers W to be formed with films. Then, the wafer boat  105  with the semiconductor wafers W loaded therein is accommodated in the processing chamber  101  again, and the semiconductor wafers W are carried into the processing chamber  101 . 
     Next, a film, e.g., a silicon nitride film in this embodiment, is formed. The silicon nitride film is formed by a well-known film forming method, such as a CVD (Chemical Vaporization Deposition) method or an ALD method. In this embodiment, the silicon nitride film is formed by an ALD method using dichlorosilane (DCS:SiH 2 Cl 2 ) gas as the silicon source gas and ammonia (NH 3 ) gas as the nitriding agent-containing gas. For example, first, dichlorosilane gas is fed into the interior of the processing chamber  101 , which is heated by the heating unit  134 . Accordingly, a thin silicon film at an atomic layer level is formed on a surface of the semiconductor wafer W to be processed. Then, the interior of the processing chamber  101  is purged using inert gas. Then, ammonia gas is plasma-excited to generate ammonia radicals, and the ammonia radicals react with the silicon film. Accordingly, the silicon film is nitrided to form a silicon nitride film. Then, the interior of the processing chamber  101  is purged using inert gas. Such a film forming cycle is repeated a plurality of times so that a silicon nitride film  3  having a designed film thickness is formed on the surface of the semiconductor wafer W to be processed. 
     In addition, when this film forming processing is performed, silicon nitride is deposited evenly on the components, which are arranged within the processing chamber  101  and coated with the silicon film  2  having the rough surface, and the silicon nitride film  3  is formed thereon (see  FIG. 4C ). 
     Next, the wafer boat  105  is carrying out of the interior of the processing chamber  101 , whereby the semiconductor wafers W are taken out of the interior of the processing chamber  101 . 
     Hereby, the film forming processing of the silicon nitride film using the film forming apparatus  100 , to which the component protection method according to the first embodiment of the present disclosure is applied, are terminated. 
     According to the component protection method of this first embodiment, the surface of the quartz component is coated with the silicon film  2  having a rough surface, which is the component protective coating, before the silicon nitride film is deposited. For this reason, it is possible to suppress the generation of cracks and delamination of a superficial layer portion of the quartz component caused by the deposition of the silicon nitride film. 
     In addition, against the silicon nitride film having a tensile stress, silicon having a compressive stress opposite thereto is used as a material of the component protective coating. For this reason, even though the silicon nitride film is deposited on the surface of the component, it is possible to relieve the stress having the silicon nitride film as described above. 
     Further, according to the first embodiment, the silicon film  2  having the rough surface having a largely undulated surface is used as the component protective coating. For this reason, the stress having the silicon nitride film can be dispersed to be more relieved. Therefore, according to first embodiment, in which the film having the rough surface, for example, the silicon film having the rough surface is used as the component protective coating, it is possible to obtain an advantage of improving an effect of relieving stress as compared with a case where a silicon film having a flat surface is used as the component protective coating. 
     Considering the surface flatness of the film to disperse and relive the stress, an average surface roughness of the silicon film  2  having the rough surface may approximately range from 3.1 to 5 nm and an average film thickness of the silicon film  2  having the rough surface may approximately range from 10 to 30 nm, in some embodiments. To this end, the silicon film  2   a  may be approximately formed to have a film thickness of 5 to 10 nm, before the surface of the silicon film  2   a  is roughened. 
     Further, as a kind of a film having a finely uneven surface, there is a polycrystalline film such as a polycrystalline silicon film. For this reason, a polycrystalline silicon film can be used as the component protective coating. However, a general surface flatness of the polycrystalline silicon film is represented by an average surface roughness of 2 to 3 nm or so. For this reason, in order to further relieve the stress, it is advantageous in some embodiments to use the silicon film  2  having the rough surface. For example, if the average surface roughness of the component protective coating exceeds the above average surface roughness of the polycrystalline silicon film, an effect of relieving stress is further improved as compared with a case where the polycrystalline silicon film is used as the component protective coating. 
     Furthermore, in order to further increase the undulation of the surface of the silicon film  2  having the rough surface, the silicon film  2   a  formed prior to the surface roughening processing is formed to include an amorphous state. If the silicon film  2   a  includes an amorphous state, surface fluidity is improved, for example, as compared with a polycrystalline state in which crystallization proceeds. For this reason, in the surface roughening processing, agglomeration of silicon is promoted, so that it is possible to further increase the undulation of the surface of the silicon film  2  having the rough surface. If the undulation of the surface of the silicon film  2  having the rough surface can be increased, it is possible to further increase an effect of dispersing the stress of the silicon nitride film  3  deposited on the silicon film  2  having the rough surface. Also, the silicon film  2   a  formed under the aforementioned processing condition is formed in a state where an amorphous silicon film is included. 
     Furthermore, a method of roughening the surface of the silicon film  2   a  also includes a method of striking the surface of the silicon film  2   a  by sputtering, sand blast or the like to form unevenness on the surface. However, a sputtering unit or sand blast unit does not exist in the interior of the processing chamber  101  of the film forming apparatus  100 . In addition, it is also impractical to install the sputtering unit or sand blast unit in the interior of the processing chamber  101 . 
     In that sense, according to a method in which after the silicon film  2   a  is formed on the surface of the component, silicon of a surface portion of the silicon film  2   a  is agglomerated by dropping the pressure of the interior of the processing chamber  101  and unevenness is formed on the surface of the silicon film  2   a,  it is not necessary to install the sputtering unit or sand blast unit to the interior of the processing chamber  101 . Also, only using the silicon source gas supply unit  115 , the evacuation unit  133 , the heating unit  134  and the like originally provided in the film forming apparatus  100 , it is possible to form the silicon film  2  having the rough surface on the surfaces of the components arranged in the processing chamber  101 . Of course, if the silicon film  2  having the rough surface, or a thin film formed on the silicon film  2  having the rough surface, e.g., the silicon nitride film  3  in this embodiment, together with the silicon film  2  having the rough surface, is etched by using a dry cleaning method, it is also possible to initialize the components. 
     According to this first embodiment, the surface of the component is directly coated with the component protective coating having an undulated surface, whereby it is possible to obtain the component protection method of a film forming apparatus capable of suppressing damage of the component of the film forming apparatus  100  even though the deposition of a thin film on the component proceeds. In addition, by including the component protection method, it is possible to form a thin film while particles are prevented from being generated in the interior of the processing chamber  101 . 
     Second Embodiment 
     The first embodiment is an example of forming the component protective coating on the surface of the component of the film forming apparatus  100  in an initial state before a silicon nitride film is formed. However, the component protective coating may also be formed after the silicon nitride film is formed. A second embodiment is such an example. 
       FIG. 5  is a flow chart illustrating an example of a component protection method according to the second embodiment of the present disclosure; and  FIGS. 6A to 6C  are enlarged sectional views schematically showing a portion of a component. 
     First, a silicon nitride film is formed using the film forming apparatus  100  (operation S 2   a ). The film forming apparatus  100  may be either in an initial state or a state where, for example, a silicon nitride film has been formed several times (about one to five times). In this embodiment, the film forming apparatus  100  in an initial state is used. In order to form a silicon nitride film, semiconductor wafers W on which the film forming processing will be performed are loaded in the wafer boat  105 . Then, the wafer boat  105  having the semiconductor wafers W loaded therein is accommodated in the interior of the processing chamber  101 . 
     Next, the film forming processing of a silicon nitride film is performed in the interior of the processing chamber  101 , for example, using the processing condition as described in the first embodiment. Accordingly, a silicon nitride film  3   a  is formed on a surface of the quartz component  1  arranged in the interior of the processing chamber  101  (see  FIG. 6A ). In this embodiment, the surface of the quartz component  1  includes an inner wall surface of the processing chamber  101 , an inner wall surface of the ceiling plate  102 , an outer peripheral surface of the wafer boat  105  including the pillars  106 , an outer peripheral surface of thermal insulation container  107 , an outer peripheral surface of the nitriding agent-containing gas dispersion nozzle  120   a,  outer peripheral surfaces of the silicon source gas dispersion nozzles  120   b  and  120   c,  an outer peripheral surface of the inert gas inlet nozzle  120   d,  and an inner wall surface of the plasma compartment wall  125 . The silicon nitride film  3   a  is formed on each surface of component  1 . 
     Next, the wafer boat  105  is carried out of the interior of the processing chamber  101 , and the semiconductor wafers W are taken out of the interior of the processing chamber  101 . Accordingly, the film forming processing using the film forming apparatus  100  is terminated. 
     Thereafter, the component protecting processing is performed as shown in operation S 1   a  of  FIG. 5 . First, the film forming apparatus  100  in which the film forming processing has been performed is prepared (operation S 11   a ). Then, the wafer boat  105  with the wafers W not loaded therein is accommodated in the processing chamber  101  of the film forming apparatus  100  in which the film forming processing has been performed (operation S 12   a ). The wafer boat  105  is what is used one time in the film forming processing in operation S 2   a.    
     Next, a component protective coating is formed on the surface of the quartz component  1  arranged in the interior of the processing chamber  101  (operation S 13   a ). In this embodiment, the component protective coating is formed on the surface of the quartz component, which is has been arranged in the interior of the processing chamber  101  and has had the silicon nitride film  3   a  formed thereon. In this embodiment, the silicon film  2   a  is formed on the surface of the quartz component  1 , which has had the silicon nitride film  3   a  formed thereon, under the same processing condition as the first embodiment (operation S 131   a ). Then, the surface roughening processing is performed on the silicon film  2   a  under the same processing condition as the first embodiment (operation S 132 ). Accordingly, the silicon film  2  having the rough surface, as the component protective coating, is formed on the silicon nitride film  3   a  (see  FIG. 6B ). 
     Thereafter, the film forming apparatus in which the component protecting processing is finished is used to perform the film forming processing (operation S 2 ). The film forming condition may be the same, for example, as the condition in operation S 2   a.  Using this film forming processing, a second silicon nitride film  3   b  is formed on the silicon film  2  having the rough surface (see  FIG. 6C ). 
       FIG. 7  is a view illustrating a stress of the silicon nitride film. 
     When a semiconductor wafer (Si-Sub) is the component, a stress of Sample I, in which a silicon nitride film (SiN) having a film thickness of 100 nm is fanned on the semiconductor wafer, and a stress of Sample II, in which there is formed a laminated film having a rough surface silicon film (Rugged Si) having an average film thickness of 10 nm formed between two silicon nitride films (SiN), each having a film thickness of 50 nm, are shown in  FIG. 7 . Sample I corresponds to a case where a film having a thickness of 50 nm is formed twice, and Sample II corresponds to this second embodiment. 
     As shown in  FIG. 7 , the stress of Sample I is 1256 MPa while the stress of Sample II is 1049 MPa, so that the stress of Sample II is relieved. 
     As such, the silicon film having the rough surface interposed between the two silicon nitride films can relieve the stress as compared with a case where the deposition of the silicon nitride film is accumulated. 
     Accordingly, also in the second embodiment, as the film having the rough surface is or becomes interposed between the thin films deposited on the surface of the component, it is possible to obtain the component protection method of a film forming apparatus capable of suppressing damage of the component of the film forming apparatus  100  even though the deposition of a thin film on the component proceeds, as in the first embodiment. In addition, by including the component protection method, the film forming method is possible to form a thin film while particles are prevented from being generated in the interior of the processing chamber  101 . 
     Third Embodiment 
     A third embodiment, which is an example of a combination of the first embodiment and the second embodiment, is an example of a component protection method which becomes more effective in practical use. 
     The film forming processing using the film forming apparatus  100  is repeated a plurality of times even after a component protective coating is formed. Whenever the film forming processing is performed, the deposition of a thin film, e.g., a silicon nitride film, is accumulated on a quartz component. Thus, the third embodiment is an example where a component protecting processing is further performed according to the number of thin film depositions, e.g., silicon nitride films. 
       FIG. 8  is a flow chart illustrating an example of a component protection method according to the third embodiment of the present disclosure. 
     In operation S 3  shown in  FIG. 8 , it is determined whether or not the film forming apparatus  100  is in an initial state. If it is in the initial state (YES), the process proceeds to operation S 1  and the component protecting processing (operation S 1  of  FIG. 3 ) is performed, which has been described with reference to  FIG. 3  and  FIGS. 4A and 4B . Thereafter, the process proceeds to operation S 2   b,  and the film forming processing using the film forming apparatus in which the component protecting processing is terminated, or the film forming processing using the film forming apparatus in which the film forming processing is terminated, e.g., the film forming processing of a silicon nitride film in this embodiment, is performed. In addition, a film forming condition in operation S 2   b  may be the same, for example, as the film forming condition in operation S 2  of the first embodiment and operation S 2   a  of the second embodiment. On the Contrary, if it is not in the initial state (NO), the process proceeds to operation S 4 . 
     In operation S 4 , it is determined whether or not the number of depositions is the number necessary to perform the component protecting processing. If the component protecting processing is needed (YES), the process proceeds to operation S lb and the component protecting processing (operation S 1   a  of  FIG. 5 ) is performed, which has been described with reference to  FIG. 5  and  FIG. 6B . Thereafter, the process proceeds to operation S 2   b,  and the silicon nitride film is formed as described above. 
     On the contrary, if the component protecting processing is not necessary (NO), the process proceeds to operation S 2   b  and the silicon nitride film is formed in the same manner. 
     In order to perform the following film forming processing, a routine from “Start” to “End” shown in  FIG. 8  has only to be repeated. 
     In this way, whenever the thin film, e.g., the silicon nitride film in this embodiment, is formed one or more times, the component protecting processing, which had been described in the first and second embodiments, may be performed. 
     According to this third embodiment, since the component protecting processing, which had been described in the first and second embodiments, is performed whenever the thin film is formed one or more times, it is advantageous to make it possible to suppress damage of the components of the film forming apparatus  100  while the film forming apparatus  100  operates in practice and the film forming processing is repeated. In addition, by including the component protection method, it is also possible to form a thin film while particles are prevented from being generated in the interior of the processing chamber  101 . 
     Furthermore, as it is determined whether or not the film forming apparatus  100  is in an initial state prior to the film forming processing, the component protecting processing described in the first embodiment can be necessarily performed in the film forming apparatus  100  in the initial state. 
     Fourth Embodiment 
       FIG. 9  is a flow chart illustrating an example of a component protection method according to a fourth embodiment of the present disclosure. 
     As shown in  FIG. 9 , the fourth embodiment is different from the third embodiment shown in  FIG. 8  in that a pre-coating processing is performed as shown in operation S 5  after the component protecting processing shown in operations S 1   a  and S 1   b  is performed. The others are the same as the third embodiment. 
     The silicon film  2  having the rough surface is formed as the component protective coating, and silicon nitride films  3  ( 3   b ) are formed as thin films to be formed. In this case, a material of the surface of the quartz component  1  arranged in the interior of the processing chamber  101  directly after the component protective coating  2  is formed becomes different from that directly after the film forming processing is performed. The material of the component protective coating  2  is silicon (Si) directly after the component protective coating  2  is formed, but the material of the component protective coating  2  is silicon nitride (SiN) directly after the film forming processing is performed. For this reason, there is a possibility for a film quality of the semiconductor wafers to be changed, although subtly, between the silicon nitride films of the semiconductor wafers formed directly after the component protective coating  2  is formed and the silicon nitride films of the semiconductor wafers formed directly after the silicon nitride films  3  ( 3   b ) are formed on the surface of the component. If the film quality is changed subtly, there is a possibility for a deviation of uniformity of the film quality of the silicon nitride films  3  to be increased between the semiconductor wafers, as the film forming processing proceeds. 
     In this respect, in this fourth embodiment, a pre-coating processing is performed to the component as shown in operation S 5  after the component protecting processing shown in operations S 1  and S 1   a  is performed, and then the silicon film  2  having the rough surface on the component is covered with a coating having the same material as the thin film to be formed, i.e. the silicon nitride coating in this embodiment. Accordingly, the material of the surface of the quartz component arranged in the interior of the processing chamber  101  directly after the component protective coating is formed can be equal to that directly after the film forming processing is performed. 
     Therefore, according to the fourth embodiment, it is possible to obtain the same advantage as the first to third embodiments and simultaneously to obtain an advantage of further suppressing an increase in deviation of uniformity of the film quality of the thin films, e.g., the silicon nitride films on the semiconductor wafers in this embodiment, between the wafers. 
     Although the present disclosure has been described with reference to the several embodiments, the present disclosure is not limited to the embodiments but can be variously modified within the scope without departing from the spirit of the present disclosure. 
     For example, although a batch type film forming apparatus has been illustrated in the aforementioned embodiments, the film forming apparatus is not limited to the batch type and may be a single type film forming apparatus. 
     Furthermore, the aforementioned embodiments have been described with the film forming apparatus  100  as an example in which the cylindrical processing chamber  101  having an open lower end and a ceiling defines a processing space allowing the film forming processing to be performed in a lump on a plurality of semiconductor wafers W. However, the film forming apparatus is not limited thereto. For example, a film forming apparatus, which includes a cylindrical quartz outer wall having a ceiling and a cylindrical quartz inner wall installed inside of the outer wall, wherein the inside space of the inner wall is defined as a processing space for performing the film forming processing on a plurality of semiconductor wafers W in a lump and a space between the outer wall and the inner wall is defined as an evacuation path, may also be applied to the aforementioned embodiments. 
     Furthermore, although the film forming apparatus  100  has the plasma generation unit  124  in the aforementioned embodiments, it is natural that the plasma generation unit  124  may be omitted. In such a case, the film forming apparatus  100  is a thermal CVD film forming apparatus or a thermal ALD film forming apparatus. 
     Moreover, although small, silicon nitride may be deposited even on an inner side of the nitriding agent-containing gas dispersion nozzle  120   a  and an inner side of the inert gas inlet nozzle  120   d,  or inner peripheral surfaces of the gas injection holes  121  a of the nitriding agent-containing gas dispersion nozzle  120   a  and an inner peripheral surface of a gas ejection portion of the inert gas inlet nozzle  120   d.  When this small deposition of silicon nitride may adversely affect the nitriding agent-containing gas dispersion nozzle  120   a  or the inert gas inlet nozzle  120   d , a silicon source gas, for example, a monosilane gas, should be supplied from the silicon source gas supply source  118   b  even to the nitriding agent-containing gas dispersion nozzle  120   a  and the inert gas inlet nozzle  120   d  when the component protective coating, e.g., the silicon film  2  having the rough surface in the aforementioned embodiments, is formed. In such a manner, the adverse influence can be solved by forming the silicon film  2  having the rough surface on the inner side of the nitriding agent-containing gas dispersion nozzle  120   a  and the inner side of the inert gas inlet nozzle  120   d,  and the inner peripheral surface of the gas injection holes  121   a  of the nitriding agent-containing gas dispersion nozzle  120   a  and the inner peripheral surface of the gas ejection portion of the inert gas inlet nozzle  120   d.    
     According to the present disclosure, it is possible to provide a component protection method of a film forming apparatus capable of suppressing damage of a component of the film forming apparatus even though a thin film is deposited, and a film forming method including the component protection method. 
     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 novel methods and apparatuses 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.