Abstract:
An apparatus to treat a substrate includes a processing chamber including a reaction space where a substrate to be treated is placed and a plasma is formed, a ferrite core having a plurality of poles disposed outside the reaction space and a connector facing the reaction space across the plurality of poles and connecting the plurality of the poles each other, a coil winding around the plurality of poles, and an electric power unit supplying electric power to the coil.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority of Korean Patent Application No. 2005-0066915, filed on Jul. 22, 2005, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present general inventive concept relates to an apparatus to treat a substrate, and more particularly, to an apparatus to treat a substrate using a ferrite core to improve plasma-generating efficiency. 
     2. Description of the Related Art 
     A substrate for a semiconductor wafer or a display apparatus (hereinafter, referred to as “substrate”) is manufactured by performing repeated deposition and etching processes of a thin film. 
       FIG. 1  is a sectional view illustrating an apparatus to treat a substrate using a ferrite core, and  FIG. 2  is a plane view illustrating the apparatus of  FIG. 1 . 
     Referring to  FIGS. 1 and 2 , a conventional apparatus to treat a substrate comprises an upper container  111  and a lower container  112  which are combined with each other. A space formed by both containers  111  and  112  is divided into an upper reaction space  113  and a lower reaction space  114  by partitions  121  and  122 . Gas is brought in the reaction spaces  113  and  114  and ionized, thereby generating plasma. An upper chuck  131  is disposed in the upper reaction space  113  and a lower chuck  132  is disposed in the lower reaction space  114 . Typically, the substrate to be treated is disposed only on the lower chuck  132 . Six toroidal ferrite cores  141  are disposed circularly on the same plane in a middle of both reaction spaces  113  and  114  at a regular interval. A coil  142  winds around each ferrite core  141 . The coil  142  winds around adjacent ferrite cores  141  in opposite directions, thereby making phases of an induced electromotive force generated by the adjacent ferrite cores  141  opposite. 
     Both reaction spaces  113  and  114  communicate with each other through a through hole  152  formed in a tube  151  passing through the center of the ferrite core  141 . Reactant gas passes through the through hole  152 . The through hole  152  is a passage of a discharging current. When treating the substrate, the coil  142  winding around the ferrite core  141  becomes a primary side and the plasma becomes a secondary side, and accordingly high-frequency electric power applied to the coil  142  is transmitted to the secondary side of the plasma. The phase difference of the induced electromotive force between the adjacent ferrite cores  141  is 180 degrees. The passage of the current induced in the plasma is formed in a closed circuit through two adjacent through holes  152 . Arrows in  FIG. 1  shows six induced currents formed between the adjacent through holes  152 . 
     In order to improve plasma-generating efficiency, the passage of the secondary current induced in the plasma should be formed in a closed circuit. Therefore, the conventional apparatus for treating the substrate  100  comprises the two reaction spaces  113  and  114 . However, only one side of the substrate is treated in the conventional apparatus for treating the substrate  100  while the plasma is generated in both sides of the substrate, thereby reducing density and efficiency of the plasma. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an aspect of the present general inventive concept to provide to an apparatus having high plasma-generating efficiency. 
     Additional aspects and advantages of the present general inventive concept will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the general inventive concept. 
     The foregoing and/or other aspects of the present general inventive concept may be achieved by providing an apparatus to treat a substrate comprising: a processing chamber comprising a reaction space where a substrate to be treated is disposed and a plasma is formed, a ferrite core comprising a plurality of poles disposed outside the reaction space and a connector to face the reaction space across the plurality of poles and to connect the plurality of the poles each other, a coil to wind around the plurality of poles, and an electric power unit to supply electric power to the coil. 
     The coil may wind around the adjacent poles in the opposite direction. 
     The connector may be formed in a closed loop. 
     The plurality of poles connected each other by the connector may be disposed in a round shape. 
     The plurality of poles connected to each other by the connector may be disposed at a regular distance. 
     The number of poles connected to each other by the connector may be even. 
     The connectors may be disposed in a round shape. 
     The connector may comprise an interior connector and an exterior connector surrounding the interior connector. 
     The interior connector and the exterior connector may be disposed coaxially in a round shape. 
     The electric power unit may supply electric power to the interior connector and the exterior connector independently. 
     The electric power unit may supply 100 kHz˜1 MHz of electric power to one of the interior connector and the exterior connector. 
     The coil may be divided into two parts, and the two parts may be connected to the electric power unit in parallel. 
     The connectors may be disposed in a toroidal shape. 
     The pole may have a cylinder shape. 
     The electric power unit may supply 100 kHz˜1 MHz of electric power. 
     The coil may be grounded through a capacitor. 
     Impedance of the capacitor may be about half of impedance of the ferrite core. 
     The apparatus to treat the substrate may further comprise a window plate disposed between the reaction space and the ferrite core. 
     The window plate may comprise alumina or quartz. 
     The apparatus to treat the substrate may further comprise an impedance matching unit disposed between the electric power unit and the coil. 
     The foregoing and/or other aspects and utilities of the present general inventive concept may also be achieved by providing an apparatus to treat a substrate comprising a processing chamber having walls to define a reaction space in which a substrate to be treated is disposed and a plasma is formed, a window plate formed as one of the walls of the processing chamber, a plurality of poles disposed on the window plate, and a connector to connect the plurality of poles. 
     The foregoing and/or other aspects and utilities of the present general inventive concept may also be achieved by providing an apparatus to treat a substrate comprising a processing chamber having walls and a window plate to define a reaction space, a plurality of poles disposed on the window plate, a connector to connect the plurality of poles such that induced current is generated beneath the window plate opposite to the plurality of poles when power is applied to the connector. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects and advantages of the present general inventive concept will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is a sectional view illustrating a conventional apparatus to treat a substrate; 
         FIG. 2  is a plan view illustrating the conventional apparatus of  FIG. 1 ; 
         FIG. 3  is a sectional view illustrating an apparatus to treat a substrate according to an embodiment of the present general inventive concept; 
         FIG. 4  is a plan view illustrating the apparatus of  FIG. 3 ; 
         FIG. 5  is a view illustrating an induced current generated in the apparatus of  FIG. 3 ; and 
         FIGS. 6 through 10  are plan views illustrating an apparatus to treat a substrate according to embodiments of the present general inventive concept. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the embodiments of the present general inventive concept, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiments are described below in order to explain the present general inventive concept by referring to the figures. 
     Referring to  FIGS. 3 and 4 , an apparatus to treat a substrate  1  is illustrated according to an embodiment of the present general inventive concept. 
     The apparatus to treat a substrate  1  comprises a reaction chamber  11  to form a reaction space  12 , an antenna unit  20  disposed over the reaction space  12  and an electric power unit  31  to supply electric power to the antenna unit  20 . 
     The reaction chamber  11  forms the reaction space  12  where plasma is formed to treat the substrate and keeps the reaction space  12  at a vacuum and at a constant temperature. A window plate  13  is provided between the reaction chamber  11  and the antenna unit  20 . The window plate  13  may be formed of insulating material such as alumina or quartz. A pair of nozzles  14  is provided in a lateral wall of the reaction chamber  11  through which the reactant gas flows. A chuck  15  is disposed in the reaction space  12 , on which a substrate  50  to be treated is seated. A vacuum port  16  is provided in a lower part of the reaction chamber  11  to keep the reaction space  12  at the vacuum and to discharge the reactant gas, a by-product, or the like to an outside thereof. The vacuum port  16  is connected to a vacuum pump (not shown). 
     The antenna unit  20  faces the reaction space  12  across the window plate  13  and comprises a ferrite core  25  and a coil  26  winding around the ferrite core  25 . 
     The ferrite core  25  comprises a plurality of poles  21  and connectors  22   a  and  22   b  to connect the adjacent poles  21  with one another. The pole  21  contacts the window plate  13  and the connectors  22   a  and  22   b  each are disposed on the pole  21  to connect the poles  21  with one another. The inside connectors  22   b  are dispose inside the outside connectors  22   a  in a circular direction. 
     The connectors  22   a  and  22   b  are formed in a toroidal shape and comprise an outside connector  22   a  and an inside connector  22   b  which are disposed coaxially. The poles  21  are disposed in the connectors  22   a  and  22   b  at a regular interval in a round shape. The pole  21  is formed in a cylinder shape and has a longer diameter than the width of the connectors  22   a  and  22   b . Each of the connectors  22   a  and  22   b  connects the even number of the poles  21 , wherein the outside connector  22   a  connects eight poles  21  and the inside connector  22   b  connects six poles  21 . 
     The connectors  22   a  and  22   b  connect the even number of the poles  21 , thereby winding the coil  26  on the adjacent poles  21  in an opposite direction from another adjacent pole  21 . Thus, the one of the coils  26  of the adjacent poles  21  is wound in one direction and then another one of the coils  26  of the adjacent poles  21  is wound in the other direction. An end portion of the coil  26  is connected to the electric power unit  31  and the other end portion of the coil  26  is grounded. The coil  26  sequentially winds around the poles  21  connected to the outside connector  22   a , and then sequentially winds around the poles  21  connected to the inside connector  22   b . The coil  26  winds around the adjacent poles  21  in the opposite direction and the even number of the poles  21  are connected to each of the connectors  22   a  and  22   b , and accordingly the coil  26  winds around all the adjacent poles  21  in the opposite direction. 
     The electric power unit  31  supplies 100 kHz˜1 MHz of electric power to the coil  26 . An impedance matching unit  32  disposed between the electric power unit  31  and the coil  26  allows the electric power of the electric power unit  31  to be supplied to the coil  26  without loss. 
     The coil  26  is grounded through a capacitor  33 . The capacitor  33  controls capacitance to distribute voltages to point ‘a’ and point ‘b’. If impedance of the capacitor  33  is about a half of an absolute value of impedance by inductance of the ferrite core  25 , both an input voltage and a ground voltage becomes minimized. Thus, the possibility of generating arcing is reduced and a capacitive coupling effect with the plasma decreases, thereby reducing ion loss in a sheath area of the window plate  13 . 
     Referring to  FIG. 5 , an induced current generated in the apparatus for treating the substrate according to the first embodiment of the present general inventive concept will be illustrated.  FIG. 5  illustrates a schematic view of  FIG. 4 , taken along line V-V. 
     When the electric power unit  31  supplies the electric power to the coil  26  in order to treat the substrate, the current flowing in the coil  26  generates a magnetic field in a sine curve, thereby generating an induced electromotive force in the opposite direction of the current of coil  26  in the reaction space  12 . Also, an induced current is generated in the plasma by the induced electromotive force and heats the plasma. The currents flow in each of the poles  21  in the opposite direction of the magnetic field. The substrate  50  is deposited or etched by the plasma. 
     In this case, a magnetic field is generated in an area (‘A’) through the connectors  22   a  and  22   b  between the poles  21 , thereby preventing the electric power from transmitting to the upper part of the connectors  22   a  and  22   b . Accordingly, the magnetic field is protected from loss due to external disturbances around the upper part of the connectors  22   a  and  22   b _and the magnetic field increases in the reaction space  12 , thereby improving plasma-generating efficiency. 
     Because the apparatus  1  to treat the substrate  50  of the present embodiment has high plasma-generating efficiency, it efficiently generates a uniform plasma even if using low-frequency electric power. As the substrate becomes larger so as to improve productivity of apparatuses using the plasma, it has been more important to generate plasma which has excellent uniformity and high density. If a plasma source is enlarged in a case that the plasma is generated with high-frequency electric power, e.g. 13.56 MHz, the plasma uniformity falls due to a transmission line effect. If the plasma is generated with a relatively low-frequency ω electric power of 100 kHz˜1 MHz, the transmission line effect is eliminated, thereby producing a broad plasma source having excellent uniformity. However, since an induced electromotive force E for generating the plasma is proportional to a magnetic field B of the antenna and the frequency ω of the electric power, the plasma-generating efficiency falls if the plasma is generated with the relatively low-frequency electric power. In the present general inventive concept, the ferrite core  25  having a high magnetic permeability may be used to improve inductive coupling efficiency between the antenna  20  and the plasma, and accordingly the uniform and high density plasma may be obtained even if using the relatively low-frequency electric power. 
     In the apparatus  1  to treat the substrate  50  of the first embodiment, the plasma is generated only in the lower part of the antenna  20  where the substrate  50  is disposed, not in the upper part thereof where the substrate  50  is not disposed. Accordingly, the plasma-generating efficiency becomes high since all the plasma is used for treating the substrate  50  without loss. 
       FIGS. 6 through 10  are plan views illustrating an apparatus to treat the substrate according to embodiments of the present general inventive concept. Like reference numerals of  FIG. 6  refer to like elements of  FIGS. 3-5 . 
     Referring to  FIG. 6 , coils  26  independently wind around poles  21  connected to an outside connector  22   a  and poles  21  connected to an inside connector. The respective coils  26  are connected to separate electric power units  31   a  and  31   b  and capacitors  33   a  and  33   b . The respective electric power units  31   a  and  31   b  supply different frequencies of electric power, for example, one of the electric power units  31   a , 31   b  may supply a high-frequency electric power of 13.56 MHz and the other one of the electric power units  31   a  and  31   b  may supply a relatively low-frequency electric power of 100 kHz˜1 MHz. 
     Referring to  FIG. 7 , there is provided a single connector  22  according to the third embodiment of the present general inventive concept. A coil  26  is divided into two parts, thereby being supplied with electric power from an electric power unit  31  in parallel. Thus, if the coil  26  is divided into two parts in parallel, inductance of an antenna  20  becomes about one-fourth of one in series. If the inductance of the antenna  20  decreases, voltage of the antenna  20  is reduced, thereby decreasing the possibility of generating arcing. 
     The pole  21  in the first embodiment through the third embodiment is of a cylinder shape with a constant diameter and the diameter is larger than the width of the connectors  22 ,  22   a  and  22   b . The shape and the diameter of the pole  21  may change as necessary. The pole  21  may be formed in a triangular prism or a square pillar, or a triangular prism along with a square pillar. The diameter of the pole  21  may be smaller than the width of the connectors  22 ,  22   a  and  22   b  or the respective poles  21  may have different diameters. The shape and size of the pole  21  are adjusted considering plasma uniformity. 
     Referring to  FIG. 8 , embodiments of  FIGS. 3-8 , the diameter of a pole  21  is smaller than the width of connectors  22   a  and  22   b  in the fourth embodiment. A coil  26  winding around the pole  21  is connected to a single electric power unit  31 . 
     Connectors  22 ,  22   a  and  22   b  of the embodiments of  FIGS. 3-8  are of a toroidal shape, i.e., a round loop, but they are not limited to the toroidal shape. The connectors  22 ,  22   a  and  22   b  may be formed in a square loop, a triangle loop, or a square loop along with a triangle loop. The shape of connectors  22 ,  22   a  and  22   b  may be adjusted according to plasma uniformity. 
     Referring to  FIG. 9 , connectors  22   c  and  22   d  are formed in a square shape. Each of the connectors  22   c  and  22   d  connects the even number of poles  21 . A coil  26  winding around the pole  21  is connected to a single electric power unit  31 . 
     In the embodiments of  FIGS. 3-9 , the connectors  22 ,  22   a ,  22   b ,  22   c  and  22   d  are formed in a closed curved line, but the connectors  22 ,  22   a ,  22   b ,  22   c , and  22   d  are not limited to the closed curved line. The connectors  22 ,  22   a ,  22   b ,  22   c  and  22   d  may be formed in a straight line or a curved line, or a combination thereof. The shape of the connectors  22 ,  22   a ,  22   b ,  22   c  and  22   d  may be adjusted according to plasma uniformity. 
     Referring to  FIG. 10 , unlike embodiments of  FIGS. 3-9 , three connectors  22   e  in a straight line are disposed parallel with one another. The respective connectors  22   e  connect five poles  21 . The number of poles  21  should not be even since the connector  22   e  is not formed in a closed loop. A coil  26  is connected to each connector  22   e  in parallel, thereby reducing the possibility of generating arcing. 
     The apparatus to treat the substrate according to the present embodiment may be used to deposit a thin film onto a substrate or to etch the thin film on the substrate. A substrate for a display apparatus, e.g., a liquid crystal display or an organic light emitting diode, or a semiconductor wafer may be treated with the apparatus according to the present general inventive concept. 
     Although a few embodiments of the present general inventive concept have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the general inventive concept, the scope of which is defined in the appended claims and their equivalents.