Abstract:
A vacuum processing apparatus using a shield member that is used in a processing chamber of the vacuum processing apparatus, that has a heating unit and that has a simple structure enabling the shield member to be thinned. A vacuum processing apparatus having a processing chamber, a gas exhaust unit for discharging gas in processing space inside the processing chamber, a support base for holding a substrate to be processed, and a shield member placed inside the processing chamber. The shield member has an outer wall structure exposed to the processing space that is located inside the processing chamber and is reduced in pressure, inner space formed inside the outer wall structure and isolated from the processing space, and a heating unit placed in the inner space and heating the outer wall structure. The inner space is communicated with the outside of the vacuum processing chamber, and the heating unit is constructed so as to extend into the inner space in a sheet-like form.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a shield member for use in a vacuum processing apparatus and a vacuum processing apparatus using the shield member.  
       BACKGROUND OF THE INVENTION  
       [0002]     Conventionally, in the manufacture of, e.g., semiconductor devices, display devices and electronic devices, use has been made of various kinds of so-called vacuum processing apparatuses that perform processing of a target substrate, such as film formation, etching, surface treatment and the like, in an atmosphere of vacuum state or depressurized state.  
         [0003]     In case of using these vacuum processing apparatuses, debris scattered during the process of film formation, etching, surface treatment or the like adhere to an inner wall surface of a processing chamber in which the target substrate is held. In this case, the debris may be turned to a deposit which in turn is peeled off in the form of particles, thus becoming a cause of contaminating the target substrate.  
         [0004]     In order to prevent the debris from adhering to the inner wall surface of the processing chamber, there has been used a so-called shield plate for covering debris-depositing portions within the processing chamber, including the inner wall surface of the processing chamber.  
         [0005]     In case such a shield plate is provided inside the processing chamber of the vacuum processing apparatus, generation of particles can be avoided by replacing the shield plate with a new one or removing the debris deposited on the shield plate during the course of maintenance. This helps to save maintenance costs and shorten a maintenance time, as compared with a case where the debris are deposited on the processing chamber and the like.  
         [0006]     However, in the event that the shield plate is arranged within the processing chamber of the vacuum processing apparatus, the shield plate is expanded or contracted in accordance with a temperature variation in the processing chamber during the course of, e.g., film formation, etching and surface treatment. This may sometimes cause the deposit adhering to the shield plate to be peeled off from the shield plate, thus creating particles. Furthermore, since the temperature of the shield plate may sometimes affect the substrate processing, it is desirable to make the temperature of the shield plate controllable.  
         [0007]     Taking this into account, there has been a case where a heating unit, e g., a heater is added to a shield plate in a processing chamber to heat the shield plate (see, Japanese Patent Laid-open Publication No. 2000-082699).  
         [0008]     However, addition of the heater to the shield plate provided within a processing chamber of a vacuum processing apparatus may cause various problems as follows.  
         [0009]     For example, in case of attaching a heater to an outside of a shield plate, the heater is required to withstand a vacuum or depressurized state developed within a processing chamber. Accordingly, a limited kind of material is usable as the heater, which may often impose a restriction on the heater in terms of its kind structure material or the like.  
         [0010]     Furthermore, the shield plate carrying the heater comes to have a complicated and large-sized structure, so that the shield plate becomes thickened. Also, the cost of the shield plate including the heater may be increased.  
       SUMMARY OF THE INVENTION  
       [0011]     It is, therefore, an object of the present invention to provide a novel and useful shield member for use in a vacuum processing apparatus that can eliminate the problems noted above and a vacuum processing apparatus using the shield member.  
         [0012]     More specifically, the present invention provides a structurally simple and thin shield member having a heating unit, which is usable within a processing chamber of a vacuum processing apparatus, and a vacuum processing apparatus using the shield member.  
         [0013]     In accordance with a first aspect of the present invention, there is provided a shield member provided in a processing chamber of a vacuum processing apparatus, the shield member including: an outer wall structure exposed to a depressurized processing space in the processing chamber, the outer wall structure having an inner space isolated from the processing space; and a heating unit provided within the inner space for heating the outer wall structure, wherein the inner space communicates with an outside of the processing chamber and the heating unit is formed into a sheet shape to extend through the inner space.  
         [0014]     In accordance with a second aspect of the present invention, there is provided a vacuum processing apparatus including: a gas exhaust unit for evacuating a processing space in a processing chamber; a support base for supporting a target substrate; and a shield member provided in the processing chamber, the shield member comprising: an outer wall structure exposed to the processing space within the processing chamber, the outer wall structure having an inner space isolated from the processing space; and a heating unit provided within the inner space for heating the outer wall structure, wherein the inner space communicates with an outside of the processing chamber and the heating unit is formed into a sheet shape to extend through the inner space.  
         [0015]     In accordance with the present invention, it becomes possible to provide a structurally simple and thin shield member having a heating unit, which is usable within a processing chamber of a vacuum processing apparatus, and a vacuum processing apparatus using the shield member. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  is a schematic view showing a vacuum processing apparatus in accordance with a first embodiment of the present invention.  
         [0017]      FIG. 2  is a perspective view schematically illustrating a shield member employed in the vacuum processing apparatus shown in  FIG. 1 .  
         [0018]      FIG. 3  shows a first modified embodiment of the vacuum processing apparatus shown in  FIG. 1 .  
         [0019]      FIG. 4  shows a second modified embodiment of the vacuum processing apparatus shown in  FIG. 1 .  
         [0020]      FIG. 5  shows a third modified embodiment of the vacuum processing apparatus shown in  FIG. 1 .  
         [0021]      FIG. 6  shows a fourth modified embodiment of the vacuum processing apparatus shown in  FIG. 1 .  
         [0022]      FIG. 7  is a view illustrating a radiation plate used in the vacuum processing apparatus shown in  FIG. 6 .  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]     Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.  
       First Embodiment  
       [0024]      FIG. 1  schematically shows a vacuum processing apparatus  10  in accordance with a first embodiment of the present invention and a shield member  100  employed in the vacuum processing apparatus  10 .  
         [0025]     Referring to  FIG. 1  the vacuum processing apparatus  10  includes a generally cylindrical processing chamber  11  having, e.g., a top opening, and a supply section  13  having, e.g., a so-called shower head structure, the supply section  13  being provided on the processing chamber  11  to close off the opening of the processing chamber  11 .  
         [0026]     A processing space  11 A is defined by the processing chamber  11  and the supply section  13 . At a bottom portion of the processing space  11 A within the processing chamber  11 , there is provided a support base  12  for supporting a target substrate W, e.g., a semiconductor wafer. The support base  12  may be configured to have a heating unit, e g., a heater.  
         [0027]     A gas exhaust unit  14  e.g., a vacuum pump, is connected to a gas exhaust port  11 B of the bottom portion of the processing chamber  11 . The gas exhaust unit  14  is capable of evacuating the processing space  11 A to a vacuum state. The term “vacuum state” used herein refers to not only a vacuum state in a strict sense but also what is called a depressurized state, i.e., a state in which the processing space is evacuated by the vacuum pump but contains a residual material, e g., a residual gas.  
         [0028]     A supply line  15  is connected to the supply section  13 , and a processing gas required to perform a substrate processing such as film formation, etching, surface treatment or the like is supplied from the supply line  15  to be introduced into the processing space  11 A through a plurality of gas inlet holes  13 A formed in the supply section  13 .  
         [0029]     Further a high frequency power supply  16  is electrically connected to the supply section  13  to apply a high frequency power thereto, thereby generating plasma to activate processing gas in the processing space  11 A. This provides a so-called capacitively coupled plasma generating unit.  
         [0030]     With the vacuum processing apparatus  10  of the present embodiment, a shield member  100  for protecting an inner wall surface of the processing chamber  11  is installed within the processing space  11 A. The shield member  100  serves to prevent debris scattered during the substrate processing such as film formation, etching and surface treatment, from adhering to the inner wall surface of the processing chamber  11 . Thus, generation of particles can be avoided by replacing the shield member with a new one or separating the shield member from the processing chamber to remove the debris deposited on the shield member during the course of maintenance. This helps to save maintenance costs and shorten a maintenance time, as compared with a case where the debris are deposited on the processing chamber and the like.  
         [0031]     In the present embodiment, the shield member  100  has an outer wall structure  101  exposed to the processing space  11 A, an inner space  101 A defined in the outer wall structure  101  and isolated from the processing space  11 A, and a heating unit  102  provided in the inner space  101 A for heating the outer wall structure  101 . The inner space  101 A communicates with an outside of the processing space  11 A and the heating unit  102  extends within the inner space  101 A in a sheet-like shape.  
         [0032]     Thus, the shield member  100  of the present embodiment has a simple structure with the heating unit. Furthermore, the shield member  100  having therein the heating unit is formed in a thin and compact structure by reducing the thickness of the outer wall structure thereof.  
         [0033]     Moreover, the inner space  101 A is in communication with the exterior of the processing chamber  11 , i.e., an outer space  11 C extending outside the processing space  11 A. In this case, the inner space  101 A communicates with the outer space  11 C via an opening  101 B of the outer wall structure  101  opened toward the outer space  11 C. Since the outer space  11 C is filled with the air and kept in an atmospheric pressure, the inner space  101 A is also filled with the air and comes to have the atmospheric pressure. That is to say, the inner space  101 A is isolated from the processing space  11 A by the outer wall structure  101  on the side of the processing space  11 A and communicates with the outer space  110  via the opening  101 B on the side of the outer space  11 C, thus kept in the atmospheric pressure.  
         [0034]     Thanks to this fact, the heating unit  102 , e.g., a heater, provided in the inner space  101 A, is isolated from a vacuum environment and can be used in an atmospheric pressure state. For example, conventionally, a heating unit is attached to a shield plate in a vacuum environment, the heating unit is subject to various restrictions in terms of a material thereof. For example, the shape and size of the heating unit is restricted in terms of its characteristics, e.g., a gas emission characteristic. In accordance with the present embodiment, the material of the heating unit is less restricted than that of the conventional one in terms of a gas emission characteristic and enjoys an increased design flexibility. This makes it possible to manufacture the heating unit with various kinds of materials in a variety of shapes thereby providing an advantageous effect that the heating unit can be easily formed into a simple, thin and small-sized shape in a cost-effective manner.  
         [0035]     Thus, it becomes possible to use a rubber heater, a polyimide resin heater, a mica sheet heater and the like, which are difficult to use in the vacuum state. This makes it possible to manufacture, e.g., a heating unit extending in a sheet-like shape within the inner space  101 A in a cost-effective manner and in a simple structure.  
         [0036]     Thanks to the features noted above, the shield member of the present embodiment can be formed into a thin shape. As shown in  FIG. 1 , the shield member, i.e., the outer wall structure  101  having the heating unit  102  provided within the inner space  101 A, can be made to have a thickness T of 5 mm or less. In this regard, there is no need for the outer wall structure  101  to have a uniform thickness over the entire region thereof. It will be sufficient if major portions of the outer wall structure  101  exposed to the processing space  11 A have a thickness of T, 5 mm or less in the present embodiment.  
         [0037]     Further, a power supply  103  for supplying an electric power to the heating unit  102  is provided in the outer space  11 C. A connecting line  102 A extends from the heating unit  102  to the power supply  103  through the opening  101 B to thereby connect the heating unit  102  to the power supply  103 . In the case where the heating unit  102  is connected to the power supply  103  provided in the outer space  11 C as described above, it is easy to connect the heating unit to external equipments including the power supply because the inner space  101 A remains in communication with the outer space  11 C. In this case, it is possible to readily connect the heating unit to the external equipments including the power supply in a simple manner without requiring, e.g., a sealing material, a gap-filling material, a flange and so forth.  
         [0038]     Next,  FIG. 2  schematically illustrates a perspective view of the shield member  100  shown in  FIG. 1 . Like parts are designated by like reference numerals in the drawings and redundant descriptions on the parts that have been described above will be omitted.  
         [0039]     Referring to  FIG. 2 , the shield member  100  has a generally cylindrical shape and is of a structure that the heating unit of, e g., sheet-like shape extends along the inner space formed within the generally cylindrical outer wall structure  101 . Furthermore, the shield member  100  is provided with, e.g., a visor-like connection portion  101 C extending radially outwardly from a peripheral edge of the cylindrical outer wall structure. The opening  101 B is formed at a leading end of the connection portion  101 C and the connecting line  102 A is inserted through the opening  101 B.  
         [0040]     As can be seen from  FIGS. 1 and 2 , the shield member  100  of generally cylindrical shape is formed along the inner wall surface of the processing chamber  11  to surround the support base  12 , thereby preventing any debris from adhering to the inner wall surface of the processing chamber  11 . The structure of the shield member is not limited to the shape illustrated in  FIGS. 1 and 2  but may be modified or changed depending on the shape of the processing chamber and the kinds of processing apparatuses. For example, the shield member may be formed into a rectangular shape to conform to a generally rectangular processing chamber. Furthermore, the shield member may be divided into plural parts to match the inner wall surface of the processing chamber. The attachment position of the shield member is not limited to the inner wall surface of the processing chamber. Alternatively, the shield member may be configured to cover structural objects in the processing chamber, e.g., the support base or the gas supply section such as the shower head and the like, thereby avoiding any formation of an attaching material or a deposit on the structural objects.  
       Second Embodiment  
       [0041]      FIG. 3  shows a vacuum processing apparatus  10 A which is a modified embodiment of the vacuum processing apparatus  10  shown in  FIG. 1 . Like parts are designated by like reference numerals in the drawings and redundant descriptions on the parts that have been described above will be omitted.  
         [0042]     Referring to  FIG. 3 , the vacuum processing apparatus  10 A of the present embodiment includes a shield member  100 A that has a temperature measuring unit  104  for measuring a temperature of the outer wall structure  101  and a control unit  105  for controlling the heating unit  102  in response to the temperature measured by the temperature measuring unit  104 .  
         [0043]     The temperature measuring unit  104  includes, e.g., a thermocouple, and a signal corresponding to the temperature measured by the temperature measuring unit  104  is sent to the control unit  105  via the connecting line  104 A. The control unit  105  controls the output of the power supply  103  in response to the temperature of the outer wall structure  101 , thus controlling the heating unit  102 .  
         [0044]     In the shield member  100 A of the present embodiment, the control unit  105  controls the output of the power supply  103  in response to the temperature measured by the temperature measuring unit  104  or the signal corresponding to the temperature. This makes it possible to control the shield member  101 A to a desired temperature, which helps to stabilize the temperature of the shield member. This suppresses peeling-off of an attaching material from the shield member, thereby reducing generation of particles. Furthermore, it is possible to reduce the influence of temperature variation of the shield member on the substrate processing such as film formation, etching and surface treatment which makes the substrate processing stable.  
         [0045]     The power supply and the control unit may be combined into a single unit that has a function of the power supply and a function of the control unit.  
       Third Embodiment  
       [0046]      FIG. 4  shows a vacuum processing apparatus  10 B which is modified from the vacuum processing apparatus  10 A shown in  FIG. 3 . Like parts are designated by like reference numerals in the drawings and redundant descriptions on the parts that have been described above will be omitted.  
         [0047]     Referring to  FIG. 4 , a shield member  100 B is provided in the vacuum processing apparatus  10 B of the present embodiment. Within the inner space  101 A of the shield member  10 B, there is provided a cooling unit  106  for cooling the outer wall structure  101 .  
         [0048]     The cooling unit  106  includes, e.g., a cooling pipe through which a coolant flows. By flowing the coolant, heat exchange occurs between the coolant and the outer wall structure  101  to thereby cool down the outer wall structure  101 . In this case, it is possible to use as the coolant various mediums, e g., a liquid coolant such as cooling water, a gas coolant such as He, and the like.  
         [0049]     The cooling unit  106  is connected to a chiller unit  107  through connecting lines  106 A which includes e.g., a supply line for supplying the coolant from the chiller unit  107  to the cooling unit  106  and a recovery line for recovering the coolant from the cooling unit  106 . The chiller unit  107  serves to cool down the coolant recovered from the cooling unit  106  and supply it to the cooling unit  106 .  
         [0050]     The control unit  105  controls the cooling power of the chiller unit  107  in response to the temperature measured by the temperature measuring unit  104  or the signal corresponding to the temperature. This makes it possible to control the shield member  100 B to a desired temperature, which helps to stabilize the temperature of the shield member. Since the shield member  100 B of the present embodiment has both the heating unit and the cooling unit, it becomes easy to stabilize the temperature of the outer wall structure  101  and to rapidly achieve a desired temperature, as compared with the case where the shield member has only the heating unit.  
       Fourth Embodiment  
       [0051]      FIG. 5  shows a vacuum processing apparatus  10 C which is another modified embodiment of the vacuum processing apparatus  10  shown in  FIG. 1 . Like parts are designated by like reference numerals in the drawings and redundant descriptions on the parts that have been described above will be omitted.  
         [0052]     Referring to  FIG. 5 , the vacuum processing apparatus  10 C includes a high frequency power supply  16 A connected to the support base  12 . This makes it possible to apply a high frequency power to the support base  12 .  
         [0053]     With such a configuration, the vacuum processing apparatus  10 C of the present embodiment is capable of applying the high frequency power to both the supply section  13  and the support base  12 . If necessary, the high frequency power may be applied to any one of the supply section  13  and the support base  12 . Moreover, the frequencies of the high frequency powers applied to the supply section  13  and the support base  12  may be different from each other.  
       Fifth Embodiment  
       [0054]     Next,  FIG. 6  shows a vacuum processing apparatus  10 D which is a still another modified embodiment of the vacuum processing apparatus  10  shown in  FIG. 1 . Like parts are designated by like reference numerals in the drawings and redundant descriptions on the parts that have been described above will be omitted.  
         [0055]     Referring to  FIG. 6 , the vacuum processing apparatus  10 D of the present embodiment includes a cover plate  17  made of a low-loss dielectric material and placed on the processing chamber  11  through a gas supply ring  20  in a position corresponding to the target substrate W on the support base  12 . The cover plate  17  is disposed to face the target substrate W.  
         [0056]     The cover plate  17  is seated on the gas supply ring  20  installed on the processing chamber  11 . A ring-shaped plasma gas passage is formed in the gas supply ring  20  and is connected to a gas supply line for supplying a processing gas for use in a process such as film formation, etching, surface treatment or the like. A plural number of gas inlet holes  20 A communicating with the plasma gas passage are formed in the gas supply ring  20  in a generally axial symmetry with respect to the target substrate W. The processing gas is supplied through the gas inlet holes  20 A into the processing space  11 A above the target substrate.  
         [0057]     A radial line slot antenna  30  that has a radiation plate as shown in  FIG. 7  is placed above the processing chamber  11  and the cover plate  17  with a gap of 4 to 5 mm left from the cover plate  17 .  
         [0058]     The radial line slot antenna  30  is seated on the gas supply ring  20  and is connected to an external microwave source (not shown) via a coaxial waveguide  21 . The radial line slot antenna  30  radiates a microwave supplied from the microwave source toward the processing gas in the processing space  11 A, thereby generating plasma.  
         [0059]     The radial line slot antenna  30  includes a disc-shaped antenna main body  22  connected to an outer waveguide tube  21 A of the coaxial waveguide  21  and a radiation plate  18  placed at the opening of the antenna main body  22 . As shown in  FIG. 7 , a multiple number of mutually orthogonal slots  18   a  and  18   b  are formed in the radiation plate  18 . A phase delay plate  19  formed of a dielectric plate having a uniform thickness is inserted between the antenna main body  22  and the radiation plate  18 . Furthermore, a core conductor  21 B constituting the coaxial waveguide  21  is connected to the radiation plate  18 .  
         [0060]     In the radial line slot antenna  30  configured as above, the microwave supplied through the coaxial waveguide  21  transmits forward while radially spreading between the disc-shaped antenna main body  22  and the radiation plate  18 , at which time the wavelength of the microwave is shortened under the action of the phase delay plate  19 . Accordingly, by forming the slots  18   a  and  18   b  in a concentric pattern and in a mutually orthogonal relationship to correspond to the wavelength of the radially transmitting microwave, it becomes possible to radiate a planar wave having a circularly polarized wave in a direction substantially perpendicular to the radiation plate  18 .  
         [0061]     Use of the radial line slot antenna  30  ensures that high density plasma is uniformly formed in the processing space  11 A immediately below the cover plate  17 . The high density plasma thus formed exhibits a low electron temperature, so that no damage is caused to the target substrate W. Moreover, since sputtering of the outer wall structure  101  of the shield member  100  is reduced, damage to the shield member is decreased.  
         [0062]     Furthermore, the vacuum processing apparatus of the present embodiment shows enhanced uniformity in plasma density on the target substrate. Therefore, when using the shield member whose temperature influence on the target substrate is suppressed, the vacuum processing apparatus of the present embodiment has a feature of improving in-plane uniformity of the target substrate during the course of a substrate processing such as film formation, etching, surface treatment and the like.  
         [0063]     As described above, the shield member of the present invention can be used in combination with a variety of vacuum processing apparatuses. The shield member is not limited to those of the foregoing embodiments but may be employed in various kinds of vacuum processing chambers.  
       INDUSTRIAL APPLICABILITY  
       [0064]     In accordance with the present invention, it becomes possible to provide a structurally simple and thin shield member employed in a processing chamber of a vacuum processing apparatus, the shield member having a heating unit, and a vacuum processing apparatus using the shield member.