Abstract:
The present disclosure provides a plasma processing apparatus capable of improving uniformity of a process on a substrate surface. The plasma processing apparatus performs a process on a substrate accommodated in a processing chamber by generating inductively coupled plasma in the processing chamber. The plasma processing apparatus includes a processing chamber main body having a top opening and formed in a container shape; an upper lid, configured to cover the top opening, having a ceiling plate formed by alternately and concentrically arranging annular dielectric members and metal members, all having different diameters, and by airtightly sealing gaps between the dielectric members and the metal members; gas introduction units provided at the metal members, for supplying a processing gas into the processing chamber; and a high frequency coil provided on an upper portion of the dielectric members and provided at the outside of the processing chamber.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of Japanese Patent Application No. 2010-240867 filed on Oct. 27, 2010, and U.S Provisional Application Ser. No. 61/413,506 filed on Nov. 15, 2010, the entire disclosures of which are incorporated herein by reference in their entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a plasma processing apparatus. 
       BACKGROUND OF THE INVENTION 
       [0003]    Conventionally, in a semiconductor device manufacturing field, there is known a plasma processing apparatus using inductively coupled plasma (ICP) as an apparatus for performing a process such as a film forming process or an etching process on a substrate such as a semiconductor wafer. 
         [0004]    In a plasma processing apparatus having a high frequency coil provided above an upper portion of a processing chamber, as a processing gas supply structure of the plasma processing apparatus using ICP, a processing gas supply device of an annular hollow pipe is provided around a substrate, i.e., in a space between the high frequency coil and the substrate. Further, a processing gas is discharged into a space above the substrate from a multiple number of gas discharge openings formed at an inner periphery of the hollow pipe (for example, see Patent Document 1). 
         [0005]    Meanwhile, in a plasma processing apparatus having a high frequency coil provided at a sidewall of a processing chamber, for example, a processing gas is discharged from an upper center of the processing chamber to a space above a substrate (for example, see Patent Document 2). 
         [0006]    Further, there is also known a plasma processing apparatus including multiple channels, each having a gas supply mechanism, and RF coils for supplying powers to the multiple channels individually (see, e.g., Patent Document 3). 
         [0007]    As the above-described processing gas supply structures, a nozzle type structure having holes or slits is used. In the plasma processing apparatus having the high frequency coil provided above the upper portion of the processing chamber, if there exists a large structure for introducing the gas to above the substrate, the substrate are blocked by the large structure, so that a non-uniform process on the substrate may be performed. Meanwhile, if a gas diffusion space is provided above the substrate and below the high frequency coil, a means to prevent an electric discharge in this space may be needed. For this reason, a region for discharging a gas is basically limited to a central portion and an outer peripheral portion of the substrate. 
         [0008]    Patent Document 1: Japanese Patent Laid-open Publication No. 2001-085413 
       Patent Document 2: Japanese Patent No. 3845154   
       [0009]    Patent Document 3: Japanese Patent Laid-open Publication No. H09-237698 
         [0010]    As described above, in the conventional plasma processing apparatus and the processing gas supply structure thereof, since the region for discharging a gas is limited, it may be difficult to improve uniformity of a process on a substrate surface by controlling a supply of the processing gas. 
         [0011]    BRIEF SUMMARY OF THE INVENTION 
         [0012]    In view of the above, the present disclosure provides a plasma processing apparatus and a processing gas supply structure thereof, capable of improving uniformity of a process on a substrate surface in comparison with a conventional apparatus. 
         [0013]    In accordance with the present disclosure, there is provided a plasma processing apparatus for performing a process on a substrate accommodated in a processing chamber by generating inductively coupled plasma in the processing chamber. The plasma processing apparatus includes a processing chamber main body having a top opening and formed in a container shape; an upper lid, configured to cover the top opening, having a ceiling plate formed by alternately and concentrically arranging multiple annular dielectric members and multiple metal members, all having different diameters, and by airtightly sealing gaps between the multiple dielectric members and the multiple metal members; multiple gas introduction units provided at the metal members, for supplying a processing gas into the processing chamber; and a high frequency coil provided on an upper portion of the multiple dielectric members and provided at the outside of the processing chamber. 
         [0014]    In accordance with the present disclosure, it may be possible to provide a plasma processing apparatus and a processing gas supply structure thereof, capable of improving uniformity of a process on a substrate surface in comparison with a conventional apparatus. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    Non-limiting and non-exhaustive embodiments will be described in conjunction with the accompanying drawings. Understanding that these drawings depict only several embodiments in accordance with the disclosure and are, therefore, not to be intended to limit its scope, the disclosure will be described with specificity and detail through use of the accompanying drawings, in which: 
           [0016]      FIG. 1  is a schematic cross sectional view showing a configuration of a plasma etching apparatus in accordance with an embodiment of the present disclosure; 
           [0017]      FIG. 2  is a cross sectional view showing major parts of the plasma etching apparatus of  FIG. 1 ; 
           [0018]      FIG. 3  is a top view illustrating a schematic configuration of the plasma etching apparatus of  FIG. 1 ; 
           [0019]      FIG. 4  is a cross sectional view illustrating a schematic configuration of a plasma etching apparatus in accordance with another embodiment of the present disclosure; and 
           [0020]      FIG. 5  is a cross sectional view illustrating a schematic configuration of an embodiment of a temperature control device in accordance with the present disclosure. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]    Hereinafter, the embodiments of the present disclosure will be described with reference to the accompanying drawings. 
         [0022]      FIG. 1  is a schematic diagram showing a configuration of a plasma etching apparatus  1  as a plasma processing apparatus in accordance with an embodiment of the present disclosure. As shown in  FIG. 1 , the plasma etching apparatus  1  may include a processing chamber  10 . The processing chamber  10  may have a substantially cylindrical shape and be made of, e.g., aluminum whose surface is anodically oxidized. Further, the processing chamber  10  may include a processing chamber main body  11  having a top opening and formed in a container shape; and an upper lid  12  disposed to cover the top opening of the processing chamber main body  11 . 
         [0023]    The upper lid  12  may be made of, e.g., aluminum whose surface is anodically oxidized. The upper lid  12  may include a frame body  13  having an opening  13   a,  and a ceiling plate  14  provided so as to close the opening  13   a  of the frame body  13 . 
         [0024]    As shown in  FIGS. 2 and 3 , the ceiling plate  14  may include multiple annular dielectric members  15   a  to  15   c  and metal members  16   a  to  16   c.  The annular dielectric members  15   a  to  15   c  and the metal members  16   a  to  16   c  are alternately and concentrically stacked. Among the metal members  16   a  to  16   c,  the metal members  16   a  and  16   b  may have annular shapes, and the metal member  16   c  may have a circular plate shape. 
         [0025]    Further, the dielectric member  15   c  may be provided outside the metal member  16   c  disposed at a central portion of the ceiling plate  14 ; the metal member  16   b  may be provided outside the dielectric member  15   c;  the dielectric member  15   b  may be provided outside the metal member  16   b;  the metal member  16   a  may be provided outside the dielectric member  15   b;  and the dielectric member  15   a  may be provided outside the metal member  16   a.  The outer side of the dielectric member  15   a  may be fitted into an inner wall portion of the opening  13   a  of the frame body  13 . 
         [0026]    In the present embodiment, although the dielectric members  15   a  to  15   c  may be made of quartz, another dielectric material, e.g., ceramic can be used. Moreover, in the present embodiment, although the metal members  16   a  to  16   c  may be made of aluminum whose surfaces are anodically oxidized, another metal, e.g., stainless steel may be used instead. 
         [0027]    The ceiling plate  14  including the dielectric members  15   a  to  15   c  and the metal members  16   a  and  16   c  may have an outwardly protruding dome shape in which the central portion thereof may be the highest and the height may gradually decrease toward a periphery thereof. Gaps between the dielectric members  15   a  to  15   c  and the metal members  16   a  to  16   c,  and a gap between the outermost dielectric member  15   a  and the frame body  13  may be airtightly sealed. 
         [0028]    As described above, by forming the ceiling plate  14  in the dome shape, a damage of the ceiling plate  14  due to a pressure difference between the interior, which is under a depressurized atmosphere, and the exterior of the processing chamber  10  can be suppressed. Further, besides using a seal member such as an O-ring, the dielectric members  15   a  to  15   c  and the metal members  16   a  to  16   c  can be airtightly sealed by joining the dielectric members  15   a  to  15   c  and the metal members  16   a  and  16   c  by using, e.g., kovar as an intermediate member. Moreover, it may also be possible to attach metal films to contact surfaces of the dielectric members  15   a  to  15   c  so as to contact the metal films to the metal members  16   a  to  16   c.    
         [0029]    A high frequency coil  17  may be provided on the dielectric members  15   a  to  15   c.  The high frequency coil  17  may be connected to a non-illustrated high frequency power supply. A high frequency power having a certain frequency, e.g., about 13.56 MHz may be applied to the high frequency coil  17 . 
         [0030]    A beam member  31  may be provided at an upper portion of the ceiling plate  14  so as to traverse the opening  13   a.  The beam member  31  may have a substantially cross shape when viewed from above, as shown in  FIG. 3 . Further, the shape of the beam member  31  is not limited to the cross shape, and the beam member  31  can have any shape. 
         [0031]    Moreover, as shown in  FIG. 1 , supporting portions  31   a  to  31   c  may be formed at lower portions of the beam member  31 . Further, the supporting portions  31   a  to  31   c  may be protruded downward to correspond to the metal members  16   a  to  16   c,  respectively. The supporting portions  31   a  to  31   c  may be in direct contact with the metal members  16   a  to  16   c.  Further, the beam member  31  and the metal members  16   a  to  16   c  may be fixed by screws  32 . In this way, the ceiling plate  14  may be supported by the beam member  31 . 
         [0032]    Gas inlets  18   a  to  18   c  may be provided at the beam member  31 . The gas inlets  18   a  to  18   c  are connected to gas channels  19   a  to  19   c  provided within the metal members  16   a  to  16   c,  respectively. 
         [0033]    As illustrated in  FIG. 2 , the gas channels  19   a  and  19   b  provided within the annular metal members  16   a  and  16   b  may include annular gas channels  190   a  and  190   b,  and vertical gas channels  191   a  and  191   b.  Here, the annular gas channels  190   a  and  190   b  are annularly formed within the annular metal members  16   a  and  16   b.  Further, the vertical gas channels  191   a  and  191   b  may connect the annular gas channels  190   a  and  190   b  with the gas inlets  18   a  and  18   b,  respectively. Multiple gas discharge openings  20   a  and  20   b  may be formed along the annular gas channels  190   a  and  190   b,  respectively, at a regular interval in a circumferential direction thereof (in  FIG. 2 , only one for each is shown). 
         [0034]    Further, the gas channel  19   c  formed within the metal member  16   c  may include a circular gas channel  190   c  having a circular shape and serving as a gas diffusion space, and a vertical gas channel  191   c  connecting the circular gas channel  190   c  and the gas inlet  18   c.  Multiple gas discharge openings  20   c  may be formed at the circular gas channels  190   c  at a regular interval. 
         [0035]    A processing gas supplied into the gas inlets  18   a  to  18   c  provided at the beam member  31  from a non-illustrated processing gas supply source may be introduced into the processing chamber  10  from the gas discharge openings  20   a  to  20   c  via the gas channels  19   a  to  19   c  provided within the metal members  16   a  to  16   c,  respectively. 
         [0036]    As illustrated in  FIG. 1 , within the processing chamber  10 , a mounting table  21  for mounting thereon a substrate, e.g., a semiconductor wafer may be provided so as to be located below the ceiling plate  14 . Accordingly, a substrate mounting surface of the mounting table  21  and the ceiling plate  14  may be arranged so as to face each other. A non-illustrated electrostatic chuck or the like for attracting and holding the substrate may be provided on the substrate mounting surface of the mounting table  21 . 
         [0037]    A non-illustrated high frequency power supply for applying a bias voltage may be connected to the mounting table  21 . Further, the metal members  16   a  to  16   c  of the ceiling plate  14  positioned to face the mounting table  21  may be connected to a certain potential, e.g., a ground potential in the present embodiment, and may function as a facing electrode facing the mounting table  21 . 
         [0038]    An annular gas exhaust space  22  for exhausting a gas downward may be formed around the mounting table  21 . The annular gas exhaust space  22  may communicate with a gas exhaust unit via a gas exhaust port (all of which are not shown). Further, a baffle plate  24  for partitioning a processing space  23  above the mounting table  21  and the annular gas exhaust space  22  may be provided around the mounting table  21 . 
         [0039]    Further, a loading/unloading port  25  for loading and unloading a substrate to be processed may be formed at a sidewall of the processing chamber main body  11 . A non-illustrated opening/closing mechanism, e.g., a gate valve may be provided at the loading/unloading port  25 . 
         [0040]    In the plasma etching apparatus  1  configured as described above, the ceiling plate  14  may include the dielectric members  15   a  to  15   c  and the metal members  16   a  to  16   c.  The processing gas may be supplied from the metal members  16   a  to  16   c,  and the dielectric members  15   a  to  15   c  may function as dielectric windows for the high frequency coil  17 . 
         [0041]    Since no gas diffusion space is provided next to the high frequency coil  17 , it may be possible to prevent an electric discharge from occurring in the gas diffusion space. Moreover, regions for discharging the processing gas may not be limited to the central portion and the peripheral portion of the substrate, but can be provided to positions corresponding to a multiple number of certain positions of the substrate in a diametrical direction. Therefore, it may be possible to uniformly supply the processing gas into the processing space  23  above the substrate. As a result, it may be possible to improve uniformity of a process on a substrate surface. Alternatively, by non-uniformly supplying the processing gas into the processing space  23 , it may be possible to control a plasma process as desired. Further, since the metal members  16   a  to  16   c  may serve as a facing electrode, it may be possible to easily control the plasma process. Moreover, as described above, since the ceiling plate  14  may be formed by alternatively connecting the dielectric members  15   a  to  15   c  and the metal members  16   a  to  16   c,  the dielectric members  15   a  to  15   c  and the metal members  16   a  to  16   c  may not be airtightly sealed because of a difference in thermal expansion coefficient therebetween. Therefore, it may be desirable to provide a temperature control device  50  for controlling the temperature of the ceiling plate  14  within a certain temperature range. 
         [0042]    Hereinafter, an embodiment of the temperature control device  50  will be explained with reference to  FIG. 5 . As depicted in  FIG. 5 , the temperature control device  50  may include a temperature maintaining cover  53  configured to cover the upper lid  12  and the beam member  31 ; an inlet pipe for introducing a temperature-controlled gas; and an outlet pipe  54  for exhausting the temperature-controlled gas. Further, the inlet pipe  52  and the outlet pipe  54  are connected to the temperature maintaining cover  53 , and a heat exchanger  55  is provided at a downstream of the outlet pipe  54 . Air or an inert gas such as helium gas may be used as the temperature-controlled gas. Further, a temperature of the temperature-controlled gas is controlled by a non-illustrated device, e.g., a vaporizer, for generating heated air or a heated gas. A thermal insulator (not shown) for blocking an influence of an exterior temperature may be provided in the temperature maintaining cover  53 . Here, the heat exchanger  55  is configured to cool the temperature-controlled gas to make the temperature of the temperature-controlled gas similar to the exterior temperature. By way of example, if the temperature of the temperature-controlled gas is low, the temperature-controlled gas may be heated by the heat exchanger  55  to have an approximately similar temperature to the exterior temperature, and then, may be evacuated to the outside. 
         [0043]    When a plasma etching process is performed on a semiconductor wafer (substrate) by the plasma etching apparatus  1  configured as described above, the substrate may be loaded into the processing chamber  10  through the loading/unloading port  25  after the non-illustrated opening/closing mechanism opens the loading/unloading port  25 . Then, the substrate may be mounted on the mounting table  21 , and may be attracted to and held on the electrostatic chuck. 
         [0044]    Thereafter, the non-illustrated opening/closing mechanism closes the loading/unloading port  25 , and then, the inside of the processing chamber  10  may be evacuated to a certain vacuum level from the annular gas exhaust space  22  by a non-illustrated vacuum pump. 
         [0045]    Subsequently, a processing gas (etching gas) having a certain flow rate may be supplied into the processing chamber  10 . At this time, the processing gas introduced from the gas inlets  18   a  to  18   c  may be supplied into the processing chamber  10  from the gas discharge openings  20   a  to  20   c  via the gas channels  19   a  to  19   c  provided within the metal members  16   a  to  16   c,  respectively. 
         [0046]    Subsequently, after the inside of the processing chamber  10  is maintained at a certain pressure, a high frequency power having a certain frequency may be applied to the high frequency coil  17 . Accordingly, in the processing space  23  above the substrate within the processing chamber  10 , ICP (Inductively Coupled plasma) of the etching gas may be generated. Further, when necessary, a high frequency bias power may be applied from a non-illustrated high frequency power supply to the mounting table  21 . Accordingly, an etching process can be performed on the substrate by using the ICP. 
         [0047]    At this time, since the processing gas is supplied from multiple positions within the processing chamber  10  by the processing gas supply structure including the gas inlets  18   a  to  18   c,  the gas channels  19   a  to  19   c,  and the gas discharge openings  20   a  to  20   c,  the processing gas can be more uniformly supplied over the substrate. Further, the processing gas supply structure is provided at the metal members  16   a  to  16   c,  and a member for blocking an electromagnetic field is not provided at the dielectric members  15   a  to  15   c  having thereon the high frequency coil  17 . Accordingly, it may be possible to suppress the non-uniformity of the process on the substrate, which is caused by blocking the electromagnetic field induced into the processing space  23  by the high frequency coil  17 . As a result, a plasma state can be uniformized, so that an etching process can be uniformly performed on each portion of the substrate. That is, it may be possible to improve uniformity of the process on the substrate surface. 
         [0048]    Upon the completion of the plasma etching process, the application of the high frequency power and the supply of the processing gas may be stopped, and the substrate may be unloaded from the processing chamber  10  in the order reverse to that described above. 
         [0049]    Moreover, the present disclosure is not limited to the above-described embodiments but can be modified in various ways. For example, the shape of the ceiling plate  14  formed at the upper lid may not be limited to the dome shape. As in the plasma etching apparatus  101  shown in  FIG. 4 , the ceiling plate  14  can have a flat plate shape. In this case, the beam member  31  may be also formed in a flat plate shape, and may include a groove  40  for burying therein the high frequency coil  17 . Moreover, as for contact surfaces of the airtightly sealed metal members  16   a  to  16   c  and the dielectric members  15   a  to  15   c,  it may be desirable to make inclined surfaces, not vertical surfaces, come into contact with each other as shown in  FIG. 4 . Further, in  FIG. 4 , like reference numerals will be given to parts corresponding to those of the plasma etching apparatus  1  and redundant description thereof will be omitted. 
         [0050]    Further, in the above-described embodiments, although the numbers of the dielectric members  15   a  to  15   c  and the metal members  16   a  to  16   c  of the ceiling plate  14  are three, respectively, the numbers of the dielectric members  15   a  to  15   c  and the metal members  16   a  to  16   c  may not be limited to three. For example, two or more than three can be provided.