Patent Publication Number: US-2010108108-A1

Title: Substrate mounting table, substrate processing apparatus and method for treating surface of substrate mounting table

Description:
FIELD OF THE INVENTION 
     The present invention relates to a substrate processing apparatus which performs, for example, a cleaning process for removing a metal oxide film on a surface of a metal film formed on a substrate; and also relates to a substrate mounting table and a method for treating a surface of the substrate mounting table. 
     BACKGROUND OF THE INVENTION 
     In order to meet the recent demands for increase in lifetime, a miniaturization of wirings and a higher speed of a semiconductor device, Cu (copper) or a Cu alloy having lower electric resistance and higher electromigration resistance has been employed as a main material for a metal wiring instead of conventionally employed Al (aluminum). When such a Cu-based metal wiring is formed on a semiconductor substrate such as a semiconductor wafer, a damascene method is generally employed because patterning Cu by plasma etching or the like is difficult. 
     To achieve electric connection between, e.g., a lower Cu-based metal wiring and an upper Cu-based metal wiring by using the damascene method, a via hole is first formed in an interlayer dielectric film formed on the lower Cu-based metal wiring. Then, the Cu-based metal is coated on the entire surface of the wafer by a plating method or the like so that the via hole is filled with the Cu-based metal. Thereafter, a CMP (Chemical Mechanical Polishing) is used to remove unnecessary Cu-based metal on the interlayer dielectric film so that only the Cu-based metal is left in the via hole. Subsequently, the upper Cu-based metal wiring is formed by coating the Cu-based metal on the entire wafer surface again. In this way, the lower Cu-based metal wiring and the upper Cu-based metal wiring are electrically connected with each other through the via hole. 
     If the surface of the lower Cu-based metal wiring is kept exposed to the atmosphere after the via hole is formed in the interlayer dielectric film, the surface would be oxidized, resulting in a formation of a native oxide film (metal oxide film) of the Cu-based metal on that surface. Especially, since Cu tends to be easily oxidized, the formation of the metal oxide film is highly likely to occur. 
     If the via hole is filled with the Cu-based metal while the oxide film still exists in the via hole, contact resistance between the lower Cu-based metal wiring and the Cu-based metal filled in the via hole may be increased due to the presence of the oxide film therebetween. In such case, fine electric characteristics of a semiconductor device to be formed on the wafer may not be obtained. Thus, the metal oxide film formed on the Cu-based metal wiring needs to be removed before the Cu-based metal is filled in the via hole. 
     As a conventional technique for removing such a metal oxide film, there is known a method of cleaning the surface of a metal wiring such as a Cu-based metal wiring by using carboxylic acid such as formic acid or the like (see, for example, Patent Document 1). By performing a cleaning process (dry cleaning) on the surface of the metal wiring by using such organic acid, the metal oxide film formed on the surface of the metal wiring can be reduced and removed. 
     Patent Document 1: Japanese Patent Laid-open Application No. 2002-270609 
     Patent Document 2: Japanese Patent Laid-open Application No. 2004-356624 
     However, the above-mentioned drying cleaning has a problem in that a part of a metal component generated as a result of the reduction of the metal oxide film on the surface of the metal wiring is dispersed in a space within a processing chamber after separated from the surface of the metal wiring layer and finally adhered to various components in the processing chamber. Especially, the dispersed metal component is highly likely to be adhered to an exposed peripheral surface of a mounting table that is not covered by the wafer. 
     Further, as such a cleaning process is repeated, the metal component dispersed onto the surface of the mounting table may be deposited, resulting in a formation of an undesired metal layer thereon. If the wafer drying cleaning process is performed in this state, the metal layer adhered to the surface of the mounting table may be etched by the organic acid used in the cleaning process, which may result in particle generation. The particles thus produced are highly likely to be adhered to a portion of the wafer surface again. Such metal contamination may affect subsequent wafer processing, causing a problem such as a failure to obtain a standard quality of the semiconductor device formed on the wafer. 
     As a solution to this problem, a cleaning operation has been conventionally performed by an operator when deposit of the metal component is accumulated on the surface of the mounting table to a certain extent. Such a mounting table cleaning operation has been generally carried out manually by way of washing away the metal deposit on the surface of the mounting table after opening, e.g., a cover of the processing chamber (wet cleaning). In case that the mounting table or members constituting the surface thereof are taken out and cleaned in the aforementioned way, the mounting table and the like has to be re-installed in the processing chamber after the surface of the mounting table is cleaned and it is also required to check if the processing chamber is normally operable or not. Thus, it takes some time to carry out the mounting table cleaning operation, during which the wafer processing cannot be performed. 
     Therefore, if the mounting table cleaning operation is frequently performed, overall throughput may be deteriorated. Moreover, the problem of metal contamination due to the metal deposit on the surface of the mounting table may be also caused in a film forming process for forming a metal film such as a Cu film on the wafer. 
     Accordingly, to prevent the occurrence of the metal contamination due to the wafer cleaning process, the surface treatment of the mounting table needs to be performed to make the surface of the mounting table as smooth as possible so that the metal component is hardly adhered thereto and can be removed readily even if the metal component is adhered. 
     Conventionally, however, it has been mainly focusing on preventing the adhesion of the deposit on the wafer surface after the deposit is peeled off from the mounting table surface. Thus, there has been an attempt to, for example, intensionally roughen the surface of the mounting table rather than to smoothen it. For example, Patent Document 2 discloses the mounting table made of quartz glass, on which a deposit such as metal cannot be easily adhered. However, Patent Document 2 also discloses intensional roughening of the surface of the mounting table to suppress peeling off of the deposit such as metal or the like from the surface of the mounting table, thus reducing the number of cleaning operations for the mounting table. 
     However, as the surface roughness of the mounting table increases, the deposit such as metal or the like adhered on that surface becomes difficult to peel off, and as the deposit becomes more difficult to peel off, a metal layer is more easily formed. Thus, the mounting table cleaning operation needs to be carried out more frequently to prevent the occurrence of wafer metal contamination which may be caused by the above-described cleaning process. 
     Moreover, as the surface roughness of the mounting table increases, it takes more time and effort for the metal film adhered on the surface thereof to be removed. 
     Conventionally, once the metal deposit is adhered to the mounting table, it could not be removed unless the operator puts in effort to wash it away with a cleaning solution, which may impose a burden on the operator and result in deterioration of processing efficiency. 
     As stated above, the conventional mounting table does not have a sufficient countermeasure to the occurrence of the metal contamination that might be caused in the wafer cleaning process. 
     SUMMARY OF THE INVENTION 
     In view of the problems set forth above, it is an object of the present invention to provide a substrate mounting table capable of suppressing adhesion of a metal component generated in performing, e.g., a cleaning process for removing a metal oxide film on a substrate, and also capable of easily removing a metal component even if the metal component is adhered to the substrate. 
     In accordance with one aspect of the present invention to solve the problems described above, there is provided a substrate mounting table of a substrate processing apparatus that performs a cleaning process of removing a metal oxide film (e.g., a native oxide film made of such as copper oxide or the like) on a surface of a metal film (e.g., a film including copper) formed on a substrate, including: a mounting table main body for mounting the substrate thereon, wherein a top surface of the mounting table main body includes a substrate mounting region, which is covered by the substrate when the substrate is mounted on the mounting table main body, and a substrate surrounding region, which is disposed outside the substrate mounting region and has a surface treated by a partial surface treatment such that the substrate surrounding region is smoother than the substrate mounting region. 
     Further, there is provided a substrate mounting table of a substrate processing apparatus that performs a cleaning process of removing a metal oxide film on a surface of a metal film formed on a substrate, including: a mounting table main body, at least a top surface of which is covered with a cover member, wherein a top surface of the cover member includes a substrate mounting region, which is covered by the substrate when the substrate is mounted on the cover member, and a substrate surrounding region, which is disposed outside the substrate mounting region and has a surface treated by a partial surface treatment such that the substrate surrounding region is smoother than the substrate mounting region. 
     In accordance with the present invention, the surface of the substrate surrounding region on the top surface of the mounting table main body or the cover member is treated by the partial surface treatment to further smoothen the substrate surrounding region exposed without being covered by the substrate. Thus, when the cleaning process is performed to remove the metal oxide film (e.g., copper oxide) on the substrate, a metal component (e.g., copper) generated by the reduction of the metal oxide film may be suppressed from being easily adhered to the substrate surrounding region with which the metal component tends to contact even though the metal component is dispersed thereto. Moreover, even if metal deposit is accumulated on the substrate surrounding region, the deposit can also be easily removed. Accordingly, an adhesion amount of the metal component on the surface of the substrate mounting table is surely reduced, so that the frequency of the substrate mounting table cleaning process can be reduced. Further, the metal component is easily removed even if adhered, so that the time for completing the substrate mounting table cleaning process can also be shortened. 
     Especially, since the substrate surrounding region is exposed without being covered by the substrate and is a horizontal region closest to the substrate among the entire surface of the substrate, the metal component is highly likely to float and adhere to the substrate surrounding region. In this regard, an effect of preventing the adhesion of the metal component to the entire surface of the substrate mounting table can be efficiently improved by smoothing this substrate surrounding region selectively. Moreover, in case that the top surface of the mounting table main body is covered by the cover member, only the cover member can be separated and cleaned when the dispersed metal component is adhered thereto. Therefore, the time required for the cleaning process of the substrate mounting table can be further shortened. 
     Further, the mounting table main body may include a side surface treated by the partial surface treatment such that the side surface of the mounting table main body has a surface roughness identical to that of the substrate surrounding region. Moreover, a side surface of the mounting table main body may be also covered by a side portion of the cover member and the side portion of the cover member may have a surface treated by the partial surface treatment such that the surface of the side portion of the cover member has a surface roughness identical to that of the substrate surrounding region. 
     Since the metal component is possibly adhered to the mounting table main body and/or the side surface of the cover member, the partial surface treatment is performed on their surfaces. Therefore, the effect of preventing the adhesion of the metal component to the entire surface of the substrate mounting table can be efficiently improved. 
     In such cases, a surface roughness of the surface treated by the partial surface treatment may be equal to or less than 1/10 of a surface roughness of the substrate mounting region. For example, a surface roughness Ra, which is an arithmetic average roughness, of the surface treated by the partial surface treatment is equal to or less than 0.1 μm. Since the partial surface treatment is performed to obtain a higher level of smoothness, the effect of preventing the adhesion of the metal component to the surface treated by the partial surface can be efficiently improved. 
     The surface treated by the partial surface treatment may be made of a quartz member having a surface treated by a fire polish process. Further, the surface treated by the partial surface treatment may be made of an aluminum member having a surface treated by a nonporous anodic oxidation process. By performing the above processes, a surface roughness Ra (an arithmetic average roughness) of the surface treated by the partial surface treatment can be equal to or less than 0.1 μm. 
     Further, in case that the cleaning process is a so-called drying cleaning process performed in a gaseous atmosphere, the metal component generated in the cleaning process is likely to float in the vicinity of the substrates. Thus, by performing the partial surface treatment to further smooth the substrate surrounding region, the effect of preventing the adhesion of the metal component to the entire surface of the substrate mounting table can be further improved. 
     In accordance with another aspect of the present invention to solve the above-mentioned problems, there is provided a substrate processing apparatus for performing a cleaning process for removing a metal oxide film on a surface of a metal film formed on a substrate, including: a vacuum evacuable processing chamber; a substrate mounting table installed in the processing chamber; and a gas supply unit for supplying at least a cleaning processing gas into the processing chamber; and a gas inlet unit, installed in the processing chamber, for introducing a gas from the gas supply unit toward the substrate on the mounting table, wherein the substrate mounting table includes a mounting table main body for mounting the substrate thereon. 
     Herein, a top surface of the mounting table main body includes a substrate mounting region, which is covered by the substrate when the substrate is mounted on the mounting table main body, and a substrate surrounding region, which is disposed outside the substrate mounting region and has a surface treated by a partial surface treatment such that the substrate surrounding region is smoother than the substrate mounting region. 
     Further, there is provide a substrate processing apparatus for performing a cleaning process for removing a metal oxide film on a surface of a metal film formed on a substrate, including: a vacuum evacuable processing chamber; a substrate mounting table installed in the processing chamber; and a gas supply unit for supplying at least a cleaning processing gas into the processing chamber; and a gas inlet unit, installed in the processing chamber, for introducing a gas from the gas supply unit toward the substrate on the mounting table, wherein the substrate mounting table includes a mounting table main body, at least a top surface of which is covered by a cover member. 
     Herein, a top surface of the cover member includes a substrate mounting region, which is covered by the substrate when the substrate is mounted on the cover member, and a substrate surrounding region, which is disposed outside the substrate mounting region and has a surface treated by a partial surface treatment such that the substrate surrounding region is smoother than the substrate mounting region. 
     In accordance with the present invention, the cleaning process for removing the metal oxide film (e.g., copper oxide) on the substrate mounting on the substrate mounting table by supplying a cleaning processing gas (e.g., an organic acid containing gas) toward the substrate while controlling an internal pressure of the processing chamber. At this time, the surface of the substrate surrounding region on the top surface of the mounting table main body or the cover member is treated by the partial surface treatment to further smoothen the substrate surrounding region exposed without being covered by the substrate. Thus, a metal component (e.g., copper) generated by the reduction of the metal oxide film may be suppressed from being easily adhered to the substrate surrounding region with which the metal component tends to contact even if the metal component is dispersed thereto. Moreover, even if metal deposit is accumulated on the substrate surrounding region, the deposit can also be easily removed. Accordingly, an adhesion amount of the metal component on the surface of the substrate mounting table is surely reduced, so that the frequency of the substrate mounting table cleaning process can be reduced. Further, the metal component is easily removed even if adhered, so that the time for completing the substrate mounting table cleaning process can also be shortened. 
     Further, a processing chamber inner wall may have a surface exposed to an inside of the processing chamber, and the surface is made of an aluminum member having a surface treated by a nonporous anodic oxidation process. Moreover, the gas inlet unit may have a surface exposed to an inside of the processing chamber, and the surface is made of an aluminum member having a surface treated by a nonporous anodic oxidation process. The dispersed metal component may be adhered to the surface of the processing chamber inner wall and/or the surface of the gas inlet unit (e.g., a shower head). Therefore, by performing the nonporous anodic oxidation process on their surfaces as well as the substrate mounting table, the adhesion of the metal component thereon can be effectively prevented. 
     In accordance with still another aspect of the present invention to solve the above-mentioned problems, there is provided a substrate treatment method for a substrate mounting table of a substrate processing apparatus that performs a cleaning process of removing a metal oxide film on a surface of a metal film formed on a substrate, wherein the substrate mounting table includes a mounting table main body for mounting the substrate thereon, and wherein a top surface of the mounting table main body includes a substrate mounting region, which is covered by the substrate when the substrate is mounted on the mounting table main body, and a substrate surrounding region, which is disposed outside the substrate mounting region. 
     The substrate treatment method includes: performing a partial surface treatment on a surface of the substrate surrounding region such that the substrate surrounding region is smoother than the substrate mounting region. 
     Further, there is provided a substrate treatment method for a substrate mounting table of a substrate processing apparatus that performs a cleaning process of removing a metal oxide film on a surface of a metal film formed on a substrate, wherein the substrate mounting table includes a mounting table main body, at least a top surface of which is covered with a cover member, and wherein a top surface of the cover member includes a substrate mounting region, which is covered by the substrate when the substrate is mounted on the cover member, and a substrate surrounding region, which is disposed outside the substrate mounting region. 
     The substrate treatment method includes: performing a partial surface processing on a surface of the substrate surrounding region such that the substrate surrounding region is smoother than the substrate mounting region. 
     In accordance with the present invention, the surface of the substrate surrounding region on the top surface of the mounting table main body or the cover member is treated by the partial surface treatment to further smoothen the substrate surrounding region exposed without being covered by the substrate. Thus, a metal component dispersed to the substrate surrounding region with which the metal component tends to contact may be suppressed from being easily adhered to the substrate surrounding region. Moreover, even if metal deposit is accumulated on the substrate surrounding region, the deposit can also be easily removed. Accordingly, an adhesion amount of the metal component on the surface of the substrate mounting table is surely reduced, so that the frequency of the substrate mounting table cleaning process can be reduced. Further, the metal component is easily removed even if adhered, so that the time for completing the substrate mounting table cleaning process can also be shortened. 
     Further, the surface treatment method described above may include performing a partial surface treatment on a side surface of the mounting table main body such that the side surface of the mounting table main body has a surface roughness identical to that of the substrate surrounding region. Further, a side surface of the mounting table main body may also be covered by a side portion of the cover member, and the surface treatment method described above may include performing a partial surface treatment on a surface of the side portion of the cover member such that the surface of the side portion of the cover member has a surface roughness identical to that of the substrate surrounding region. 
     Since the metal component is possibly adhered to the mounting table main body and/or the side surface of the cover member, the partial surface treatment is performed on their surfaces. Therefore, the effect of preventing the adhesion of the metal component to the entire surface of the substrate mounting table can be efficiently improved. 
     In such cases, a surface roughness of the surface treated by the partial surface treatment may be equal to or less than 1/10 of a surface roughness of the substrate mounting region. Further, a surface roughness Ra, which is an arithmetic average roughness, of the surface treated by the partial surface treatment, may be equal to or less than 0.1 μm. 
     Since the partial surface treatment is performed to obtain a higher level of smoothness, the effect of preventing the adhesion of the metal component to the surface treated by the partial surface can be efficiently improved. 
     In accordance with still another aspect of the present invention to solve the above-mentioned problems, there is provided a substrate mounting table of a substrate processing apparatus for performing a film forming process for forming a metal film on a substrate or a cleaning process for removing a metal oxide film on the metal film, including: a first member having a substrate mounting surface for mounting the substrate thereon; and a second member, installed to surround the substrate mounting surface, having a substrate surrounding region disposed outside the substrate mounting region, wherein the substrate mounting surface and the substrate surrounding surface are treated by a partial surface treatment such that their surface roughnesses Ra, which is an arithmetic roughness, are equal to or less than 0.1 μm. 
     Further, there is provided a substrate mounting table of a substrate processing apparatus for performing a film forming process for forming a metal film on a substrate or a cleaning process for removing a metal oxide film on the metal film, including: a mounting table main body, at least a top surface of which is covered with a cover member, wherein the cover member includes: a first cover member having a substrate mounting surface for mounting the substrate thereon; and a second cover member, installed to surround the substrate mounting surface, having a substrate surrounding surface disposed outside the substrate mounting surface, wherein the substrate mounting surface and the substrate surrounding surface are treated by a partial surface treatment such that their surface roughnesses Ra, which is an arithmetic roughness, are equal to or less than 0.1 μm. 
     In accordance with the present invention, a metal component (e.g., copper) generated when the film forming process or the cleaning process is performed on the substrate may be suppressed from being easily adhered to the substrate surrounding surface and can be easily removed even if the metal component is deposited on the substrate surrounding surface. Further, the metal component is also hardly adhered to the substrate mounting surface even if the metal component is dispersed into a space between the substrate and the substrate mounting surface. Moreover, even if metal deposit is accumulated on the substrate surrounding region, the deposit can also be easily removed. Accordingly, an adhesion amount of the metal component on the surface of the substrate mounting table is surely reduced, so that the frequency of the substrate mounting table cleaning process can be reduced. Further, the metal component is easily removed even if adhered, so that the time for completing the substrate mounting table cleaning process can also be shortened. 
     Further, in accordance with the present invention, the mounting table main body is divided into the first member including the substrate mounting surface having the substrate mounting region and the second member including the substrate surrounding surface having the substrate surrounding region. Therefore, the partial surface processing can be easily performed on the substrate mounting surface as well as the substrate surrounding surface. Moreover, the cover member of the mounting table main body is divided into the first cover member including the substrate mounting surface having the substrate mounting region and the second cover member including the substrate surrounding surface having the substrate surrounding region. Thus, the partial surface processing can be easily performed on the substrate mounting surface as well as the substrate surrounding surface. 
     Further, the second member of the mounting table main body may include a side surface treated by the partial surface treatment such that the side surface of the second member of the mounting table main body has a surface roughness identical to that of the substrate surrounding region. Further, a side surface of the mounting table main body is also covered by a side portion of the second cover member and the side portion of the second cover member has a surface treated by the partial surface treatment such that the surface of the side portion of the second cover member has a surface roughness identical to that of the substrate surrounding region. 
     Since the metal component is possibly adhered to the mounting table main body and/or the side surface of the cover member, the partial surface treatment is performed on their surfaces. Therefore, the effect of preventing the adhesion of the metal component to the entire surface of the substrate mounting table can be efficiently improved. 
     Further, each of the surfaces treated by the partial surface treatment may be made of a quartz member having a surface having a surface treated by a fire polish process. Further, each of the surfaces treated by the partial surface treatment is made of an aluminum having a surface treated by a nonporous anodic oxidation process. By performing the above processes, a surface roughness Ra (an arithmetic average roughness) of each of the surfaces treated by the partial surface treatment can be equal to or less than 0.1 μm. 
     In the present specification, 1 sccm is (10 −6 /60)m 3 /sec.
         In accordance with the present invention, a metal component cannot be easily adhered to a surface of a mounting table main body even when a cleaning process for removing a metal oxide film or a film forming process for forming a metal film is performed on a substrate. Moreover, even if metal deposit is accumulated, the deposit can be easily removed. Accordingly, an adhesion amount of the metal component on the surface of the substrate mounting table is surely reduced, so that the frequency of mounting table cleaning process can be reduced. Also, the metal component is easily removed even if adhered, so that the time for completing the substrate mounting table cleaning process can be shortened.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a vertical cross sectional view illustrating a configuration example of a cleaning processing apparatus in accordance with an embodiment of the present invention. 
         FIG. 2  presents a vertical cross sectional view illustrating a film structure of a wafer on which a cleaning process is performed by the cleaning processing apparatus shown in  FIG. 1 . 
         FIG. 3  sets forth a partial cross sectional view illustrating a configuration example of a mounting table shown in  FIG. 1 . 
         FIG. 4  depicts a partial cross sectional view illustrating another configuration example of the mounting table shown in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Throughout the specification and drawings, like reference numerals are used for like or corresponding parts, and redundant description thereof will be omitted. 
     (Configuration Example of a Cleaning Processing Chamber) 
     First, a configuration example of a substrate processing apparatus in accordance with an embodiment of the present invention will be explained with reference to the accompanying drawings.  FIG. 1  is a vertical cross sectional view showing a schematic configuration of a cleaning processing apparatus  100  used as the substrate processing apparatus in accordance with the present embodiment. The cleaning processing apparatus  100  includes an airtightly sealed processing chamber  110  having a substantially cylindrical shape and is configured to accommodate a wafer W in the processing chamber  110  and perform a cleaning process for removing a metal oxide film formed on the wafer W. 
     A shower head  140  serving to introduce a gas from a gas supply unit  170  toward the substrate on a mounting table  120  is installed at a ceiling wall  112  of the processing chamber  110 . The shower head  140  includes an upper block body  142 , an intermediate block body  144  and a lower block body  146 . 
     The lower block body  146  is provided with alternately arranged first gas injection openings  150  for discharging a first processing gas and second gas injection openings  152  for injecting a second processing gas. The upper block body  142  is provided with, on its top surface, a first gas inlet port  154  for introducing the first processing gas and a second gas inlet port  156  for introducing the second processing gas. 
     The upper block body  142  is provided with, in its inside, a plurality of first upper gas channels  158  branched off from the first gas inlet port  154  and extended in horizontal and vertical directions; and a multitude of second upper gas channels  160  branched off from the second gas inlet port  156  and extended in horizontal and vertical directions. Further, the intermediate block body  144  is provided with, in its inside, a plurality of first intermediate gas channels  162  respectively communicating with the first upper gas channels  158  and extending in horizontal and vertical directions; and a multitude of second intermediate gas channels  164  respectively communicating with the second upper gas channels  160  and extending in horizontal and vertical directions. The first intermediate gas channels  162  communicate with the first gas injection openings  150 , while the second intermediate gas channels  164  communicate with the second gas injection openings  152 . 
     The cleaning processing apparatus  100  in accordance with the present embodiment includes the gas supply unit  170 . 
     The gas supply unit  170  includes an organic acid containing gas supply source  172  for supplying an organic acid containing gas as a cleaning processing gas; and an inert gas supply source  174  for supplying an inert gas. In the present embodiment, carbonic acid is used as the organic acid. Examples of the carbonic acid may be oxalic acid, formic acid, acetic acid, citric acid, succinic acid, and so forth. Further, a N 2  (nitrogen) gas, an Ar (argon) gas, or the like may be used as the inert gas. 
     The organic acid containing gas supply source  172  is connected with an organic acid containing gas supply line  176 , and the inert gas supply source  174  is connected with an inert gas supply line  178 . A valve  180 A, a mass flow controller (MFC)  182  and a valve  180 B are installed on the organic acid containing gas supply line  176  in sequence from the upstream side thereof. In the same manner, a valve  184 A, a mass flow controller (MFC)  186  and a valve  184 B are installed on the inert gas supply line  178  in sequence from the upstream side thereof. 
     The organic acid containing gas supply line  176  is connected to the first gas inlet port  154  provided in the upper block body  142  of the shower head  140 , and the inert gas supply line  178  is connected to the second gas inlet port  156 . 
     With this configuration, the organic acid containing gas from the organic acid containing gas supply source  172  is introduced into the shower head  140  via the organic acid containing gas supply line  176  and the first gas inlet port  154  of the shower head  140 , and then injected into the processing chamber  110  from the first gas injection openings  150  after flowing through the first upper gas channels  158  and the first intermediate gas channels  162 . In the same manner, the inert gas from the inert gas supply source  174  is introduced into the shower head  140  via the inert gas supply line  178  and the second gas inlet port  156  of the shower head  140 , and then injected into the processing chamber  110  from the second gas injection openings  152  after flowing through the second upper gas channels  160  and the second intermediate gas channels  164 . 
     The shower head  140  in accordance with the present embodiment is of a post-mix type such that the organic acid containing gas and the inert gas are independently supplied into the processing chamber  110 . Accordingly, in a cleaning process, it may be possible to supply the organic acid containing gas and the inert gas alternately as well as simultaneously, and it may be also possible to supply either one of them. Further, a pre-mix type shower head may be employed instead of the shower head  140 . Moreover, only the organic acid gas containing gas supply line  176  may be installed without the inert gas supply line  178 . 
     A circular opening  114   a  is provided in a central portion of a bottom wall  114  of the processing chamber  110 , and a gas exhaust chamber  190  extending downward from the bottom wall  114  to cover the opening  114   a.  A gas exhaust unit  132  is connected to a sidewall of the gas exhaust chamber  190  via a gas exhaust pipe  192 . By operating the gas exhaust unit  132 , the inside of the processing chamber  110  can be depressurized to a specific vacuum level. 
     Installed at a sidewall  116  of the processing chamber  110  are a loading/unloading port  116   a  through which the wafer W is loaded into or unloaded from the processing chamber  110 ; and a gate valve  134  configured to open or close the loading/unloading port  116   a.    
     A mounting table  120  for mounting the wafer W thereon is provided in the processing chamber  110 . The mounting table  120  includes a circular plate-shaped mounting table main body  122  for holding the wafer W thereon and a cylindrical supporting column  125  supporting the mounting table main body  122 . A lower end of the supporting column  125  is installed in a bottom portion of the processing chamber  110  by using bolts or the like, whereby the mounting table  120  is fixed to the inside of the processing chamber  110 . The mounting table main body  122  includes, for example, a circular plate-shaped main body plate  123 ; and an upper cover member (main body cover member)  124 , which covers a top surface (substrate mounting surface) and a side surface (side surface) of the main body plate  123 . In the mounting table main body  122  having the upper cover member  124 , the top surface and the side surface of the upper cover member  124  serves as a top surface (substrate mounting surface) and a side surface (side surface) of the mounting table main body  122 . 
     Further, the mounting table main body  122  may have only the main body plate  123  without the upper cover member  124 . In such case, the main body plate  123  itself serves as the mounting table main body  122 , such that the top surface and the side surface of the main body plate  123  also serve as the top surface (substrate mounting surface) and the side surface (side surface) of the mounting table main body  122 . Further, a lower cover member  126  for covering both a bottom surface of the main body plate  123  and a surface of the supporting column  125  may be additionally installed. In this configuration, the entire surface of the mounting table  120  is covered with the upper cover member  124  and the lower cover member  126 . 
     Here, specific configuration examples of the cover members  124  and  126  will be explained with reference to the relevant drawings.  FIG. 3  is an enlarged vertical cross sectional view illustrating a part of the mounting table  120 . As shown in  FIG. 3 , the lower cover member  126  is configured to partially or entirely cover a side surface of the main body plate  123  as well as the bottom surface of the main body plate  123  and the surface of the supporting column  125 . The side portion of the upper cover member  124  is preferably configured to cover a radially outermost side of lower cover member  126 . In this configuration, since the side surface of the main body plate  123  is covered by the lower cover member  126  and the upper cover member  124  placed thereon, the entire surface of the mounting table  120  can be covered by the upper cover member  124  and the lower cover member without any gap present therebetween. 
     Further, as illustrated in  FIG. 3  for example, a stepped portion  124   a  may be formed between a substrate mounting region  220  and a substrate surrounding region  222  on the top surface (substrate mounting surface) of the upper cover member  124 , so that the substrate mounting region  220  for mounting the wafer W thereon is positioned lower than the substrate surrounding region  222  around it. This configuration allows the wafer W to be mounted on a preset position on the mounting table  120 . 
     Preferably, the main body plate  123  and the upper cover member  124  included in the mounting table main body  122  as well as the supporting column  125  and the lower cover member  126  may be formed of a material having high heat resistance and high corrosion resistance against a cleaning processing gas, e.g., organic acid, to which these components are exposed during the cleaning process. Further, the upper cover member  124  may be preferably formed of a material to which a floating metal component (e.g., copper) generated in the cleaning process is hardly adhered. Such a material may be, for example, a quartz member (quartz glass) such as quartz (SiO 2 ). It is empirically known that compared to Si, quartz is a material to which a metal component such as Cu is not easily adhered and quartz has a high corrosion resistance to the organic acid and a high heat resistance. Likewise, the main body plate  123  constituting the mounting table main body  122  and the supporting column  125  may be made of a quartz member such as quartz glass. 
     Further, a heater  128  is embedded in the main body plate  123  of the mounting table main body  122 . The heater  128  generates heat depending on a power supplied from a heater power supply  130 , whereby the temperature of the wafer W is controlled. 
     Further, the mounting table  120  further includes a wafer support mechanism (not shown) capable of moving up and down while holding the wafer W thereon so as to transfer the wafer W to/from a transfer mechanism such as a transfer arm. The wafer support mechanism includes, for example, three wafer supporting pins (lifter pins), and each wafer supporting pin is configured to be protruded above and retracted below the surface of the mounting table main body  122  through a hole provided through the mounting table main body  122 . 
     (Specific Example of Cleaning Process) 
     Now, a cleaning process performed by the cleaning processing apparatus  100  in accordance with the above-described embodiment will be explained. The cleaning processing apparatus  100  performs a cleaning process on a wafer W having a film structure as illustrated in  FIG. 2 , for example. The wafer W has an insulating film  202  formed on a bare Si substrate  200 ; a metal wiring layer  204  formed in the insulating film  202 ; and an interlayer dielectric film  206  formed on the insulating film  202 . In the present embodiment, the metal wiring layer  204  is made of Cu. Further, the insulating film  202  and the interlayer dielectric film  206  are made of, e.g., SiO 2  (silicon oxide) or a Low-k material having a lower dielectric constant than SiO 2 . 
     Devices such as MOS (Metal Oxide Semiconductor) transistors and/or a wiring layer electrically connecting these devices may be formed between the bare Si substrate  200  and the insulating film  202 . In such a case, the wiring layer is electrically connected with, e.g., the metal wiring layer  204 . 
     As for the wafer W, the interlayer dielectric film  206  on the metal wiring layer  204  is selectively etched and thus provided with a via hole  208 . By filling the via hole  208  with metal, an upper metal wiring (not shown) to be formed on the interlayer dielectric film  206  layer is allowed to be electrically connected with the metal wiring layer  204 . 
     However, if the via hole  208  is formed in the interlayer dielectric film  206 , a part of the surface of the metal wiring layer  204  is exposed. In this state, if the wafer W is left under the atmosphere or under a low vacuum, the exposed surface of the metal wiring layer  204  may be oxidized, resulting in a formation of a native metal oxide film  210  thereon. In the present embodiment, the metal wiring layer  204  is made of Cu which is highly oxidizable. Thus, the metal oxide film  210  made of CuO x  (copper oxide) may be formed in a short time. 
     If the via hole  208  is filled with the metal while the metal oxide film  210  still exits, the metal oxide film  210  may be interposed between the metal wiring layer  204  and the metal buried in the via hole  208 , resulting in an increase of contact resistance therebetween. In such case, fine electric characteristics of a semiconductor device formed on the wafer W may not be obtained. 
     For that reason, the wafer W is loaded into the processing chamber  110  of the cleaning processing apparatus  100  of the present embodiment before the process of filling the via hole  208  with the metal is performed, and a cleaning process (dry cleaning process) for removing the metal oxide film  210  is performed therein. 
     Such cleaning process (dry cleaning process) is carried out as follows, for example. First, the wafer W is loaded into the processing chamber  110  from the loading/unloading port  116   a  of the processing chamber  110  and is mounted on the mounting table  120 . Then, the gate valve  134  is closed, and the wafer W is heated up to a preset temperature, e.g., 100 to 400° C. by supplying a power to the heater  128  from the heater power supply  130 . Concurrently, the internal pressure of the processing chamber  110  is controlled by the gas exhaust unit  132 . 
     When the temperature of the wafer W reaches the preset temperature and the internal pressure of the processing chamber  110  is stabilized at a certain pressure level, e.g., 0.1 Pa to 101.3 kPa, the valves  180 A and  180 B of the organic acid containing gas supply line  176  are opened, and an organic acid containing gas, e.g., a formic acid gas, is supplied from the organic acid containing gas supply source  172  into the first gas injection openings  150  of the shower head  140 , and the formic acid gas is then injected from the first gas injection openings  150  toward the surface of the wafer W on the mounting table  120 . An injection amount of the formic acid gas is controlled to, e.g., 10 to 500 sccm by the mass flow controller  182 . 
     Further, an inert gas such as a N 2  gas may be introduced into the processing chamber  110  together with the formic acid gas. In such case, after the valves  184 A and  184 B of the inert gas supply line  178  are opened, the N 2  gas is supplied into the second gas injection openings  152  of the shower head  140  from the inert gas supply source  174 , and then is injected from the second injection openings  152  toward the surface of the wafer W on the mounting table. An injection amount of the inert gas is controlled by the mass flow controller  186 . In this way, a gaseous mixture of the formic acid gas and the N 2  gas is supplied onto the surface of the wafer W. 
     After the formic gas or the gaseous mixture of the formic acid gas and the N 2  gas is supplied on the surface of the wafer W, the inside of the processing chamber  110  is maintained at a preset pressure and the wafer W is heated at a preset temperature for, e.g., 30 to 300 seconds. As a result, the CuO x  forming the metal oxide film  210  on the metal wiring layer  204  of the wafer W is converted to formate and reduced thereafter. Further, H 2 O (moisture) and/or CO 2  (carbon dioxide) generated by this chemical reaction is exhausted to the outside of the processing chamber  110  by the gas exhaust unit  132 . 
     Through the above-described cleaning process, the metal oxide film  210  formed on the surface of the metal wiring layer  204  is removed. Then, if the process of filling the via hole  208  with the metal is performed on this wafer W subsequently, fine electric characteristics can be obtained for the contact resistance between the metal wiring layer  204  and the metal in the via hole  208 . 
     (Adhesion of Cu to the Mounting Table) 
     When the above-stated cleaning process is performed on the wafer W in the processing chamber  110 , the CuO x  of the metal oxide film  210  is reduced, so that Cu is generated. At this time, a part of the Cu may be dispersed from the wafer W into the space within the processing chamber  110 . The majority of the dispersed Cu may reach the vicinity of the wafer W and fall down. 
     Accordingly, as shown in  FIG. 3 , given that the top surface (substrate mounting surface) of the mounting table main body  122  (i.e., the top surface of the upper cover member  124 ) is divided into the substrate mounting region  220 , which is covered by the wafer W when the wafer W is mounted thereon and the substrate surrounding region  222  disposed outside the substrate mounting region  220  and exposed to the inside of the processing chamber, the Cu dispersed from the wafer W to the vicinity thereof is highly likely to fall down onto the substrate surrounding region  222  of the mounting table  120  while the Cu dispersed far away from the wafer W may be exhausted out by being carried by an air flow formed within the processing chamber  110 . Thus, it is highly likely that the dispersed Cu is adhered to the substrate surrounding region  222  of the mounting table  120 . Moreover, since a side region  224  which is a side surface of the mounting table main body  122  (i.e., a side surface of the upper cover member  124 ) is adjacent to the wafer W, the dispersed Cu is may also be adhered thereto even though an adhesion amount of the Cu to the side region  224  is smaller than that adhered to the substrate surrounding region  222 . 
     In contrast, since the substrate mounting region  220  is covered by the wafer W during the cleaning process, it is very unlikely that the dispersed Cu is adhered to this region during the cleaning process. 
     As stated above, the Cu dispersed from the wafer W in the cleaning process may be adhered to the surface of the substrate surrounding region  222  of the upper cover member  124 . If such dispersed Cu is continuously deposited thereon, an undesired Cu layer may be formed thereon. If the undesired Cu layer is formed on the upper cover member  124  of the mounting table  120 , the undesired Cu layer is highly likely to be etched by organic acid during a subsequent cleaning process and adhered to an undesired portion of the wafer W again. 
     Thus, in the substrate processing apparatus configured to perform the cleaning process for removing the metal oxide film, there is a demand for a mounting table to which a metal component such as Cu is hardly adhered and from which the metal component can easily removed even if the metal component is adhered. This mounting table is different from a conventional mounting table which is designed to suppress peeling of a metal component adhered to the surface thereof. The mounting table  120  in accordance with the present embodiment is characterized in that surface treatment is partially performed on its surface, which is highly likely to be in contact with the metal component such as the dispersed Cu generated in the cleaning process, such that the dispersed Cu is hardly adhered to this surface and the surface has smoothness (surface roughness) capable of easily removing the metal component therefrom even if the dispersed Cu is adhered. 
     (Surface Treatment of the Mounting Table) 
     Now, the surface treatment of the mounting table in accordance with the present embodiment will be explained. In case that the upper cover member  124  (main body cover member) serving as the surface of the mounting table  120  is made of, e.g., a quartz member as described earlier, the surface of the quartz member may be treated by a sand blast method in which a treatment target surface is polished by blasting an abrasive of, e.g., No. 500 toward the treatment target surface at a preset pressure. Prior to performing the partial surface treatment in accordance with the present embodiment, a surface roughness (arithmetic average roughness) Ra of the upper cover member  124  is about 0.8 to 1.0 μm. 
     However, with such a level of smoothness (surface roughness), a sufficient effect of preventing adhesion of Cu to the surface of the mounting table may not be obtained as described in the conventional case. Especially, since it is highly likely that the dispersed Cu is adhered to the substrate surrounding region  222  and the side region  224  of the upper cover member  124 , it is preferable that the partial surface treatment is further performed on these regions  222  and  224  to obtain higher smoothness. 
     In this regard, the partial surface treatment is performed on at least the substrate surrounding region  222  and the side region  224  of the upper cover member  124  in the mounting table  120  in accordance with the present embodiment. Specifically, if the partial surface treatment is conducted on the surfaces of the substrate surrounding region  222  and the side region  224  of the upper cover member  124 , their surface roughnesses may be reduced to less than or equals to 1/10 of a surface roughness (e.g., surface roughness of the substrate mounting region  220 ) before the partial surface treatment is performed. For example, since a surface roughness Ra (arithmetic average roughness) before conducting the surface treatment is about 1.0 μm, it is preferable to perform the partial surface treatment such that their surface roughnesses (arithmetic average roughness) Ra become equal to or less than 0.1 μm. 
     As a specific method of the partial surface treatment (hereinafter, also referred to as a “high-smoothness surface treatment”) in accordance with the present embodiment, a fire polish (flame polish) method may be employed, for example. In this polishing method, the respective surfaces of the substrate surrounding region  222  and the side region  224  of the upper cover member  124  are exposed to a flame, whereby the quartz constituting these surfaces is softened. 
     Further, as for the mounting table  120  in accordance with the present embodiment, when the mounting table main body  122  has only the main body plate  123  without the upper cover member  124 , the partial surface treatment as described above may be performed on a top and a side surface region of the main body plate  123 , which are corresponding to the substrate surrounding region  222  and the side region  224  of the upper cover member  124 , respectively. 
     In case of the mounting table  120  in accordance with the present embodiment as described above, the partial surface treatment is performed to further smoothen parts of the top surface of the mounting table main body  122  (e.g., the substrate surrounding region  222  and the side region  224 ), which are exposed without being covered by the wafer W. Thus, when the cleaning process is performed to remove the metal oxide film such as copper oxide on the wafer W, the metal component such as copper generated by the reduction of the metal oxide film may be suppressed from being easily adhered to the surface region with which the metal component tends to contact even though the metal component is dispersed thereto. 
     As a result, the effect of preventing adhesion of the metal component improves, so that formation of an undesired metal layer such as a Cu layer on each surface of the substrate surrounding region  222  and the side region  224  of the upper cover member  124  can be suppressed even when the cleaning process for the wafer W is repeatedly performed. 
     Thus, compared to conventional cases, the frequency of maintenance of the cleaning processing apparatus  100  for removing a deposit on the surface of the mounting table  120  can be greatly reduced. Such reduction of the maintenance frequency for the cleaning processing apparatus  100  leads to an improvement of throughput in the manufacture of wafers W. 
     Further, since surface smoothness of each of the substrate surrounding region  222  and the side region  224  of the upper cover member  124  is high, the metal component such as Cu can be easily removed even if it is adhered to such regions. That is, in the maintenance of the cleaning processing apparatus  100 , Cu adhered to the surfaces of the substrate surrounding region  222  and the side region  224  can be easily removed. At this time, Cu can be readily washed away by using, e.g., ethanol or pure water without having to use any special liquid chemical. Therefore, the time required for the maintenance of the cleaning processing apparatus  100  can be reduced, and the throughput for the manufacture of wafers W can be further improved. 
     Moreover, in the present embodiment, since the surface treatment is partially performed only on the mounting table  120 ′s surface portion (e.g., the substrate surrounding region  222  and the side region  224  of the upper cover member  124 ) to which the floating metal component such as Cu is can be easily adhered, manufacturing cost of the mounting table  120  can be greatly reduced compared to a case of performing a same surface treatment on the entire surface of the mounting table  120 . 
     Now, a result of an experiment conducted to observe an effect of the mounting table in accordance with the present embodiment will be explained. In this experiment, a cleaning process was performed by using the cleaning processing apparatus  100  to reduce and remove a copper oxide film formed on a wafer W by way of supplying a gaseous mixture of a formic acid gas and a N 2  gas onto the wafer W mounted on the mounting table  120 . 
     Here, an upper cover member A made of quartz and having a substrate surrounding region on which the surface treatment is being performed by a fire polish (flame polish) method; and an upper cover member B made of quartz without performing the surface treatment thereon are prepared. By using mounting tables on which the upper cover members A and B are respectively installed, a cleaning process was performed repeatedly on a plurality of wafers W consecutively. Then, the upper cover members A and B were taken out, and adhesion state of Cu on their substrate surrounding regions was investigated. 
     In the experiment, Cu deposits were observed on the substrate surrounding regions of both of the upper cover members A and B with naked eyes. However, the adhesion amount of Cu deposits on the upper cover member A treated by the surface treatment was much smaller than the amount of Cu deposits on the upper cover member B not treated by the surface treatment. 
     Moreover, the adhesion of the Cu deposits on the upper cover member B was so strong that the Cu deposits could not be washed away just by ethanol or pure water. Besides, the Cu deposits could not be easily removed even with a special liquid chemical, and it took as much as 30 minutes or more to remove all the Cu deposits when observed with naked eyes. 
     In contrast, the adhesion of the Cu deposits on the upper cover member A was so weak that they could be removed by ethanol or pure water, and could be more easily washed away when a special liquid chemical is used. In this case, it took only 30 seconds or less to complete the removal of all the Cu deposits when observed with naked eyes. That is, it was found that in case that the surface treatment was performed, all the Cu deposits could be removed in a very short period of time which is equal to or less than 1/60 of the time period required in case that the surface treatment was not performed. 
     According to the experiment as described above, it was proved that when the surface treatment was performed on the upper cover member, the amount of Cu deposits adhered to the upper cover member&#39;s portion treated by the surface treatment can be reduced compared to that in case without performing the surface treatment. It was also found out that even if the Cu deposits are adhered to the portion of the upper cover member treated by the surface treatment, they can be very easily removed. 
     Further, in the present embodiment, although the partial surface treatment (high-smoothness surface treatment) was conducted on the respective surfaces of the substrate surrounding region  222  and the side region  224  among the entire surface of the upper cover member  124 , the present invention is not limited thereto. For example, it may be also possible to perform the partial surface treatment (high-smoothness surface treatment) only on the surface of the substrate surrounding region  222  to which the dispersed Cu is most likely to be adhered, depending on the pattern of adhesion of the dispersed Cu. In such case, an increase of cost accompanied by the high-smoothness surface treatment in accordance with the present embodiment can be minimized while effectively preventing adhesion of the dispersed Cu to the surface of the mounting table. 
     Moreover, as illustrated in  FIG. 3 , the stepped portion  124   a  is formed at the top surface (substrate mounting surface) of the upper cover member  124  (main body cover member) such that a region on which the wafer W is mounted is lower than its surrounding region. In such case, if the lower region is slightly larger than the size of the wafer W, an area of the lower region outside the wafer W and a surface of the stepped portion  124   a  may also be regarded as the substrate surrounding region  222 , and it may be possible to perform thereon the high-smoothness surface treatment of the present embodiment. 
     Since the surface of the upper cover member  124  in accordance with the present embodiment is made of quartz, the above-described fire polish method can be employed for the high-smoothness surface treatment. On the contrary, if the surface of the upper cover member  124  is made of aluminum (Al) or an Al compound such as alumina, high surface smoothness can be obtained by performing, for example, a nonporous anodic oxidation process. More specifically, an OGF (Out Gas Free; registered trademark) surface treatment may be employed. By the OGF surface treatment, an Al 2 O 8  composition film having a thickness of about 7000 Å (angstrom) is formed on a treated surface. The film thus obtained features a small outgassing amount (no greater than about 1/10 of a general alumite film) as well as very high surface smoothness. Further, thermal shock resistance or plasma corrosion resistance of the treated surface can also be improved. 
     The high-smoothness surface treatment may also be performed on various components within the processing chamber  110  such as the ceiling wall  112 , the bottom wall  114 , the sidewall  116  and the shower head  140 . In case that these components are made of Al, the above-mentioned OFG surface treatment may be employed. Typically, the surfaces of the components within the processing chamber  110  have been mechanically polished, and a surface roughness Ra (arithmetic average roughness) of, e.g., the shower head  140  is in the range from about 1.3 to 1.8 μm. However, by performing the OGF surface treatment on the surface of this shower head  140 , a higher level of smoothness can be obtained, so that adhesion of dispersed Cu can be effectively prevented. 
     Moreover, although the mounting table  120  in accordance with the present embodiment includes the upper cover member  124  and the lower cover member  126 , the present invention may be applied to a mounting table without having these cover members. In such case, it is preferable to directly perform the high-smoothness surface treatment on a surface of a substrate mounting region and a side surface of the mounting table. 
     Further, although the mounting table  120  in accordance with the present embodiment includes two kinds of cover members (the upper cover member  124  and the lower cover member  126 ), the present invention may also be applied to a mounting table having three or more kinds of cover members. Examples of the three cover members may be a cover member covering the top surface of the mounting table main body  122 ; a cover member covering the side surface of the mounting table main body  122 ; and a cover member covering the bottom surface of the mounting table main body  122  and the surface of the supporting column  125 . In case of such a mounting table having multiple kinds of cover members, it is preferable to select cover members depending on Cu dispersion state and to perform the high-smoothness surface treatment on the selected cover members. 
     Though the metal wiring layer  204  is made of Cu in the above-described embodiment, the present invention may also be applied to a case where the metal layer  204  may be formed of Ag (silver), Co (cobalt), Ni (nickel), Mn (manganese), or the like. 
     Further, in accordance with the present embodiment of the present invention, the mounting table is applied to the apparatus configured to perform the cleaning process for removing the metal oxide film  210  on the surface of the metal wiring layer  204  exposed in the opening formed by etching the interlayer dielectric film  206 , the present invention is not limited thereto. The present invention may also be applied to a mounting table of an apparatus configured to perform another kind of cleaning process, e.g., a cleaning process for removing an oxide film formed on a metal surface after CMP (Chemical-mechanical polishing) is carried out. 
     Further, the mounting table in accordance with the present embodiment may be applied to not only the cleaning processing apparatus configured to perform the cleaning process but also a film forming apparatus configured to perform a film forming process for forming a metal film (e.g., a Cu film) on a substrate. 
     In such a film forming apparatus, a metal film such as a Cu film on a wafer W is formed by, e.g., a CVD (Chemical Vapor Deposition), a PVD (Physical Vapor Deposition) method, or the like. For example, in a film forming process for forming the Cu film by the CVD method, the wafer W is heated to a certain temperature (e.g., 100 to 300° C.), and a thin Cu film is formed on the surface of the wafer W by supplying a preset processing gas on the wafer W. In such case, a gas containing copper hexafluoroacetylacetonate trimethylvinylsilane (Cu(hfac)TMVS) as a source gas; a hydrogen gas (H 2 ) as a reducing gas for the Cu(hfac)TMVS; and an argon gas (Ar) as an inert gas may be used as the processing gas. In such film forming process, Cu is also adhered to the surface of the mounting table as well as to the surface of the wafer W. Thus, a problem of metal contamination may occur, as in the case of the cleaning process. 
     That is, if the film forming process is repeatedly performed without removing a metal deposit on the surface of the mounting table, the metal deposit may be peeled off from the surface of the mounting table, resulting in particle generation. Thus, the metal deposit on the mounting table surface needs to be removed periodically. In the conventional mounting table on which the surface treatment in accordance with the present embodiment is not performed, a cleaning process has taken a long time because removal of the metal deposit is not easy. 
     In contrast, by applying the mounting table treated by the surface treatment in accordance with the present embodiment to the film forming apparatus, an adhesion of metal component can be suppressed during the film forming process, and they can be very easily removed even if the metal component is adhered. Accordingly, the frequency of mounting table cleaning process can be reduced, and the time for completing the mounting table cleaning process can also be shortened. 
     Further, it may be also possible to use the apparatus shown in  FIG. 1  as a film forming apparatus. In such case, the gas supply unit  170  may further include, for example, one more gas supply system for supplying a source gas into the processing chamber  110  via a vaporizer (not shown) in addition to the dual gas supply system shown in  FIG. 1 . For example, the source gas such as Cu(hfac)TMVS may be supplied via the vaporizer, and a H 2  gas as a reducing gas may be supplied from the organic acid containing gas supply source  172  instead of the organic acid containing gas, and an Ar gas may be supplied from the inert gas supply source  174 . Here, though the example has been described for the case of performing the film forming process without exciting plasma, the present invention may also be applied to a case of performing a film forming process by exciting plasma. 
     Moreover, in the above-described embodiment, though the upper cover member  124  is configured to have the substrate mounting region  220  and the substrate surrounding region  222  thereon as shown in  FIG. 3 , the present invention is not limited thereto. For example, it may be also possible to constitute the upper cover member  124  with a first cover member  310  forming the substrate mounting region  220  and a second cover member  320  forming the substrate surrounding region  222  as illustrated in  FIG. 4 . 
     To be more specific, the first cover member  310  is formed in, e.g., a circular plate shape covering the top surface of the main body plate  123 . The top surface of the first cover member  310  includes a substrate mounting surface  312  having the substrate mounting region  220  and an extended surface  314  extended outward from the substrate mounting surface  312  to surround it. The extended surface  314  is depressed lower than the substrate mounting surface  312 , and the second cover member  320  is formed so as to cover the extended surface  314  and the side surface of the main body plate  123 . The top surface of the second cover member  320  serves as a substrate surrounding surface  322  having the substrate surrounding region  222 . 
     As described, by constituting the upper cover member  124  with the first cover member  310  and the second cover member  320 , the above-described high-smoothness surface treatment can be easily performed on the substrate surrounding surface  322 . Further, the high-smoothness surface treatment can also be easily performed on the substrate mounting surface  312  as well as on the substrate surrounding surface  322 . Accordingly, since the high-smoothness surface treatment can be performed on both the substrate surrounding region  222  and the substrate mounting region  220 , metal component such as Cu is hardly adhered to the substrate mounting region  220  even if the metal component is dispersed into a space between the wafer W and the substrate mounting region  220 , and can be easily removed even if adhered. 
     When a film forming process for forming a metal film such as Cu or the like is performed by, e.g., a CVD method, a source gas containing metal and a reducing gas are supplied onto a wafer W mounted on the mounting table  120 , and a film is formed on the substrate by a reduction of the metal. Thus, the metal such as Cu is easily deposited on the substrate surrounding surface  322  and is also easily dispersed into a space between the wafer W and the substrate mounting surface  312 . Thus, in the substrate processing apparatus that performs such a film forming process, it is preferable to perform the high-smoothness surface treatment on the substrate mounting surface  312  as well as the substrate surrounding surface  322 . 
     Further, the above-stated high-smoothness surface treatment may be also performed on the side surface of the second cover member  320  and on the surface of the stepped portion  124   a  of the second cover member  320 . 
     Moreover, in case that a mounting table does not have these cover members, the mounting table may be made up of a first member having a substrate mounting surface  312  serving as a substrate mounting region  220  for mounting a wafer W thereon and a second member having a substrate surrounding surface  322 , which is provided to surround the substrate mounting surface  312  and serves as a substrate surrounding region  222  outside the substrate mounting surface  312 . In such case, it may be preferable to directly perform the above-described high-smoothness surface treatment on the substrate mounting surface  312  of the first member as well as on the substrate surrounding surface  322  of the second member. Moreover, the high-smoothness surface treatment may also be performed on the side surface of the second member. 
     While the invention has been shown and described with respect to the embodiment in connection with the accompanying drawings, the present invention is not limited thereto. It would be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of ideas disclosed in the claims. 
     INDUSTRIAL APPLICABILITY 
     The present invention has many advantages when it is applied to a substrate processing apparatus, a substrate mounting table and a method for treating a surface of the substrate mounting table.