Abstract:
An ion beam apparatus includes a plasma chamber with a grid assembly installed at one end of the plasma chamber and a plasma sheath controller disposed between the plasma chamber and the grid assembly. The grid assembly includes first ion extraction apertures. The plasma sheath controller includes second ion extraction apertures smaller than the first ion extraction apertures. When the plasma sheath controller is used in this configuration, the surface of the plasma takes on a more planar configuration adjacent the controller so that ions, extracted from the plasma in a perpendicular direction to the plasma surface, pass cleanly through the apertures of the grid assembly rather than collide with the sidewalls of the grid assembly apertures. A semiconductor manufacturing apparatus and method for forming an ion beam are also provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Korean Patent Application No. 10-2007-0009476, filed Jan. 30, 2007, the disclosure of which is hereby incorporated herein by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an apparatus using plasma, and more particularly, to an ion beam apparatus having a plasma sheath controller and a semiconductor surface treatment apparatus employing the same. 
     2. Description of the Related Art 
     Semiconductor manufacturing apparatuses using plasma are widely used, for example, a plasma etcher, a plasma enhanced chemical vapor deposition (PECVD) apparatus, a surface treatment apparatus for metal or polymer, a synthesizing apparatus for new materials, an adhesion apparatus for different thin films, and so on. The semiconductor manufacturing apparatuses using plasma may include an ion beam apparatus. 
       FIG. 1  is a partial cross-sectional view of a conventional ion beam apparatus. 
     Referring to  FIG. 1 , the conventional ion beam apparatus includes first and second ion extraction grids  15  and  17  disposed at one surface of a plasma chamber (not shown). The ion extraction grids  15  and  17  have aligned ion extraction apertures  16 . A positive voltage is applied to the first ion extraction grid  15 . A negative voltage is applied to the second ion extraction grid  17 . The second ion extraction grid  17  may be grounded. 
     The plasma chamber functions to generate plasma  11 . Generally, a plasma sheath  13  is formed between the plasma  11  and an object opposite thereto. In this case, a plasma surface  12  exists at a position spaced apart from the opposite object by a thickness of the plasma sheath  13 . Therefore, the plasma sheath  13  is formed between the plasma  11  and the first ion extraction grid  15 . 
     The ion extraction grids  15  and  17  extract ions from the plasma  11  to discharge the ions via the ion extraction apertures  16 . The extracted ions are accelerated in the form of an ion beam  19  while the ions pass through the ion extraction apertures  16 . 
     Generally, an increase in density of the plasma  11  or expansion of the ion extraction apertures  16  is advantageous to an increase of ion flux of the ion beam  19 . When the ion extraction apertures  16  have a diameter much smaller than the thickness of the plasma sheath  13 , the plasma surface  12  is formed parallel to a surface of the first ion extraction grid  15 . However, the higher the density of the plasma  11 , the smaller the thickness of the plasma sheath  13 . 
     Further, when the density of the plasma  11  is increased more, the plasma sheath  13  is formed along the ion extraction apertures  16 . That is, the plasma  11  bows outward into the ion extraction apertures  16 . In this case, the plasma surface  12  assumes a periodic curved/spherical form into the ion beam pathways through the ion extraction apertures  16 . 
     The disadvantage of this deformation of the plasma surface is that the ions in the plasma  11  are extracted in a direction perpendicular to the plasma surface  12 . Therefore, the ions extracted from the curved plasma surface  12  collide with the ion extraction grids  15  and  17 . As a result, the ion flux of the ion beam  19  is somewhat reduced. This detrimental effect becomes even more pronounced as the density of the plasma  11  (e.g. the energy supplied to the plasma) is increased. It therefore becomes impossible to obtain high ion flux of the ion beam  19 . 
     Semiconductor manufacturing apparatus using plasma is disclosed in U.S. Pat. No. 4,450,031, entitled “Ion Shower Apparatus,” filed by Ono, et al. According to Ono, et al., an ion shower apparatus including a shield grid and an ion extraction grid is provided. However, an ion beam apparatus capable of increasing ion flux is still required. 
     Accordingly, the need remains for methods of improving the ion flux of an ion beam. 
     SUMMARY OF THE INVENTION 
     An embodiment of the invention provides an ion beam apparatus with high ion flux. 
     Another embodiment of the invention provides a semiconductor manufacturing apparatus using an ion beam apparatus with high ion flux. 
     Still another embodiment of the invention provides a method for producing an ion beam with a high ion flux. 
     In one aspect, the invention is directed to an ion beam apparatus having a plasma sheath controller. The apparatus includes a plasma chamber. A grid assembly is installed at one end of the plasma chamber. The grid assembly includes first ion extraction apertures. The plasma sheath controller is disposed between the plasma chamber and the grid assembly. The plasma sheath controller includes second ion extraction apertures smaller than the first ion extraction apertures. 
     In some embodiments of the present invention, the second ion extraction aperture may have a width smaller than the thickness of a plasma sheath of the plasma chamber. 
     In other embodiments, the plasma sheath controller may be in contact with the grid assembly. In addition, the plasma sheath controller may be a conductor. 
     In still other embodiments, the plasma sheath controller may be a net grid or a porous material layer. In this case, the plasma sheath controller may be formed of one selected from the group consisting of graphite, metal, and carbon nano tubes. 
     In yet other embodiments, the grid assembly may include a first ion extraction grid and a second ion extraction grid. In this case, the first ion extraction grid may be interposed between the plasma sheath controller and the second ion extraction grid. In addition, the plasma sheath controller may be thinner than the first ion extraction grid. A positive voltage may be applied to the first ion extraction grid. A negative voltage may be applied to the second ion extraction grid, and the second ion extraction grid may be grounded. 
     In yet other embodiments, the grid assembly may include the first ion extraction grid, the second ion extraction grid, and a third ion extraction grid. In this case, the second ion extraction grid may be interposed between the first ion extraction grid and the third ion extraction grid. In addition, a positive voltage may be applied to the third ion extraction grid. 
     In another aspect, the present invention is also directed to a semiconductor manufacturing apparatus having a plasma sheath controller. The manufacturing apparatus includes a plasma chamber. A specimen chamber in communication with the plasma chamber is provided. A grid assembly is disposed between the plasma chamber and the specimen chamber. The grid assembly includes first ion extraction apertures. The plasma sheath controller is disposed between the plasma chamber and the grid assembly. The plasma sheath controller includes second ion extraction apertures smaller than the first ion extraction apertures. 
     In some embodiments, a gas inlet port may be disposed at one surface of the plasma chamber. In addition, an exhaust port may be disposed in the specimen chamber. A wafer stage may be disposed in the specimen chamber. 
     In other embodiments, the second ion extraction apertures may have a width smaller than the thickness of a plasma sheath of the plasma chamber. 
     In yet another aspect, the present invention is also directed to a method for providing an ion beam from a plasma source. The method comprises positioning a plasma sheath controller adjacent the plasma sheath of a plasma source and in front of a grid assembly so that multiple apertures of the plasma sheath controller are in communication with each aperture of the grid assembly and the resulting plasma sheath is substantially coplanar with a surface of the plasma sheath controller. A voltage is applied to the grid assembly. Ions are extracted through apertures in the plasma sheath controller and then through apertures in the grid assembly to form an ion beam. 
     Where a first extraction grid of the grid assembly and a second extraction grid, aligned with the first, are provided, the method further comprises applying the voltage to the first extraction grid and a different voltage to the second extraction grid. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other objects, features and advantages of the invention will become more apparent from the following more particular description of exemplary embodiments of the invention and the accompanying drawings. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. 
         FIG. 1  is a partial cross-sectional view of a conventional ion beam apparatus. 
         FIG. 2  is a cross-sectional view of a semiconductor surface treatment apparatus in accordance with exemplary embodiments of the present invention. 
         FIG. 3  is an enlarged perspective view of a plasma sheath controller and an ion extraction grid in accordance with exemplary embodiments of the present invention. 
         FIGS. 4 and 5  are enlarged perspective views of portion E 2  of  FIG. 3  according to alternate embodiments of the invention. 
         FIGS. 6 to 8  are enlarged cross-sectional views of portion E 1  of  FIG. 2  according to alternate embodiments of the invention. 
         FIGS. 9 and 10  are graphs of ion current characteristics representing variation of ion beams extracted by use of the plasma sheath controller. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the present invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. In the drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. Like numbers refer to like elements throughout. 
       FIG. 2  is a cross-sectional view of a semiconductor surface treatment apparatus in accordance with exemplary embodiments of the present invention. 
     Referring to  FIG. 2 , a plasma chamber  31  and a specimen chamber  51  in communication with the plasma chamber  31  may be provided. A grid assembly  49  may be disposed between the plasma chamber  31  and the specimen chamber  51 . A plasma sheath controller  41  or  41 ′ may be disposed between the plasma chamber  31  and the grid assembly  49 . 
     A gas inlet port  37  may be provided at one surface of the plasma chamber  31 . A process gas may be injected into the plasma chamber  31  through the gas inlet port  37 . The plasma chamber  31  may be surrounded by an induction coil  33 . The induction coil  33  may be connected to a radio frequency (RF) power supply  35 . The RF power supply  35  and the induction coil  33  may function to generate plasma  38  in the plasma chamber  31 . 
     An exhaust port  59  may be provided at one side of the specimen chamber  51 . The exhaust port  59  may be in communication with an exhaust apparatus such as a vacuum pump (not shown). Byproducts in the plasma chamber  31  and the specimen chamber  51  may be discharged through the exhaust port  59 . The vacuum pump may function to maintain the interior of the plasma chamber  31  and the specimen chamber  51  at a low pressure. 
     A wafer stage  53  may be disposed in the specimen chamber  51 . A wafer  55  may be mounted on the wafer stage  53 . A mask pattern  56  may be provided on the wafer  55 . 
     The grid assembly  49  may include a first ion extraction grid  43  and a second ion extraction grid  45 . The first ion extraction grid  43  may be disposed between the plasma chamber  31  and the second ion extraction grid  45 . The second ion extract grid  45  may be disposed between the first ion extraction grid  43  and the specimen chamber  51 . An insulating member  44  may be interposed between the first ion extraction grid  43  and the second ion extraction grid  45 . The first ion extraction grid  43  and the second ion extraction grid  45  may be conductors. The insulating member  44  may be an insulator such as an oxide layer or a nitride layer. 
     A positive voltage may be applied to the first ion extraction grid  43 . In this case, the second ion extraction grid  45  may be grounded. In addition, a negative voltage may be applied to the second ion extraction grid  45 . 
     Alternatively, a negative voltage may be applied to the first ion extraction grid  43 . In this case, the second ion extraction grid  45  may be grounded. In addition, a positive voltage may be applied to the second ion extraction grid  45 . 
     The grid assembly  49  may include first ion extraction apertures  49 H. The first ion extraction apertures  49 H may pass through the first ion extraction grid  43 , the insulating member  44 , and the second ion extraction grid  45 . The first ion extraction apertures  49 H may have a cylinder shape or a slit shape. 
     The plasma sheath controller  41  or  41 ′ may be disposed between the plasma chamber  31  and the grid assembly  49 . The plasma sheath controller  41  or  41 ′ may be a conductor or an insulator. The plasma sheath controller  41  or  41 ′ may include second ion extraction apertures smaller than the first ion extraction apertures  49 H. The plasma sheath controller  41  or  41 ′ may be thinner than the first ion extraction grid  43 . 
     The plasma sheath controller  41  or  41 ′ may be in contact with the first ion extraction grid  43 . In this case, the plasma sheath controller  41  or  41 ′ may have the same potential as the first ion extraction grid  43 . 
     The plasma  38  may be generated in the plasma chamber  31 . A plasma sheath  40  may exist between the plasma  38  and the plasma sheath controller  41  or  41 ′. The plasma sheath controller  41  or  41 ′ may function to control formation of the plasma sheath  40 . Therefore, a plasma surface  39  may be spaced apart from the plasma sheath controller  41  or  41 ′ by the thickness of the plasma sheath  40 . 
     The thickness of the plasma sheath  40  may vary depending on the density of the plasma  38 . For example, when the density of the plasma  38  is increased, the thickness of the plasma sheath  40  may be decreased. The plasma surface  39  may be controlled by adjusting the size of the second ion extraction apertures. The second ion extraction apertures may have a width smaller than the thickness of the plasma sheath  40 . When the second ion extraction apertures have a width smaller than the thickness of the plasma sheath  40 , the plasma surface  39  may be substantially parallel to a surface of the plasma sheath controller  41  or  41 ′. 
     The grid assembly  49  may function to extract an ion beam  50  through the first ion extraction apertures  49 H. The ion beam  50  may be injected onto a surface of the wafer  55 . 
     As described above, the plasma surface  39  may be controlled parallel to the surface of the plasma sheath controller  41  or  41 ′. Generally, ions extracted from the plasma  38  may have a directionality perpendicular to the plasma surface  39 . Therefore, it is possible to minimize collision of the ions extracted from the plasma  38  with the grid assembly  49  and scattering of the ions. Eventually, it is possible to remarkably increase ion flux of the ion beam  50  compared to the conventional art. 
       FIG. 3  is a perspective view of the plasma sheath controller  41  or  41 ′ and the ion extraction grids  43  and  45  in accordance with exemplary embodiments of the present invention, and  FIGS. 4 and 5  are enlarged perspective views of portion E 2  of  FIG. 3 . 
     Referring to  FIGS. 3 ,  4  and  5 , the first ion extraction grid  43  may include the first ion extraction apertures  49 H. The second ion extraction grid  45  may also include the first ion extraction apertures  49 H. The first ion extraction grid  43  and the second ion extraction grid  45  may be aligned with reference to the first ion extraction apertures  49 H. 
     As shown in the drawings, the first ion extraction apertures  49 H may have a cylinder shape. On the other hand, the first ion extraction apertures  49 H may have a slit shape. The first ion extraction grid  43  and the second ion extraction grid  45  may be conductors. The first ion extraction grid  43  and the second ion extraction grid  45  may have the same thickness or different thicknesses. For example, the second ion extraction grid  45  may be thicker than the first ion extraction grid  43 . 
     The plasma sheath controller  41  or  41 ′ may be a net grid  41  or a porous material layer  41 ′. The plasma sheath controller  41  or  41 ′ may include second ion extraction apertures  41 H. The second ion extraction apertures  41 H may be smaller than the first ion extraction apertures  49 H. The plasma sheath controller  41  or  41 ′ may be thinner than the first ion extraction grid  43 . The plasma sheath controller  41  or  41 ′ may be a conductor or an insulator. 
     As shown in  FIG. 4 , the plasma sheath controller  41  or  41 ′ may be a net grid  41 . The net grid  41  may be formed of one selected from the group consisting of graphite, metal, and carbon nano tube. The net grid  41  may include the second ion extraction apertures  41 H. The second ion extraction apertures  41 H may be smaller than the first ion extraction apertures  49 H. The net grid  41  may be thinner than the first ion extraction grid  43 . 
     As shown in  FIG. 5 , the plasma sheath controller  41  or  41 ′ may be a porous material layer  41 ′. In this case, the porous material layer  41 ′ may be a conductor or an insulator. For example, the porous material layer  41 ′ may be a porous metal layer or a porous ceramic layer. The porous material layer  41 ′ may include the second ion extraction apertures  41 H. The second ion extraction apertures  41 H may be smaller than the first ion extraction apertures  49 H. The porous material layer  41 ′ may be thinner than the first ion extraction grid  43 . 
       FIGS. 6 to 8  are enlarged cross-sectional views of portion E 1  of  FIG. 2 . 
     Referring to  FIGS. 2 and 6 , the plasma sheath controller  41  or  41 ′ may be attached to the grid assembly  49 . The grid assembly  49  may include the first ion extraction grid  43 , the insulating member  44 , and the second ion extraction grid  45 . In this case, the plasma sheath controller  41  or  41 ′ may be in contact with the first ion extraction grid  43 . 
     The plasma sheath controller  41  or  41 ′ may have a first thickness T 1 . The first ion extraction grid  43  may have a second thickness T 2 . The insulating member  44  may have a third thickness T 3 . The second ion extraction grid  45  may have a fourth thickness T 4 . The first thickness T 1  may be smaller than the second thickness T 2 . That is, the plasma sheath controller  41  or  41 ′ may be thinner than the first ion extraction grid  43 . The second thickness T 2  and the fourth thickness T 4  may be the same or different. 
     The grid assembly  49  may include the first ion extraction apertures  49 H. The first ion extraction apertures  49 H may pass through the first ion extraction grid  43 , the insulating member  44  and the second ion extraction grid  45 . The first ion extraction apertures  49 H may have a first width W 1 . 
     The plasma sheath controller  41  or  41 ′ may include the second ion extraction apertures  41 H. The second ion extraction apertures  41 H may have a second width W 2 . The second width W 2  may be smaller than the first width W 1 . That is, the second ion extraction apertures  41 H may be smaller than the first ion extraction apertures  49 H. The plasma sheath controller  41  or  41 ′ may be a conductor or an insulator. 
     The plasma sheath  40  may exist between the plasma  38  and the plasma sheath controller  41  or  41 ′. The plasma sheath  40  may have a fifth thickness T 5 . The fifth thickness T 5  may vary depending on the density of the plasma  38 . For example, the higher the density of the plasma  38 , the thinner the fifth thickness T 5 . That is, a distance between the plasma surface  39  and the plasma sheath controller  41  or  41 ′ is decreased as the density of the plasma  30  is increased. 
     The second width W 2  may be smaller than the fifth thickness T 5 . That is, the second ion extraction apertures  41 H may be smaller than the fifth thickness T 5  of the plasma sheath  40 . For example, the fifth thickness T 5  may be several times larger than the second width W 2 . When the second width W 2  is smaller than the fifth thickness T 5 , the plasma surface  39  may be parallel to the surface of the plasma sheath controller  41  or  41 ′. As described above, it is possible to control the plasma surface  39  by adjusting the size of the second ion extraction apertures  41 H. 
     A positive voltage may be applied to the first ion extraction grid  43 . In this case, the second ion extraction grid  45  may be grounded. In addition, a negative voltage may be applied to the second ion extraction grid  45 . When the plasma sheath controller  41  or  41 ′ is a conductor, the plasma sheath controller  41  or  41 ′ may have the same potential as the first ion extraction grid  43 . 
     The first ion extraction grid  43  and the second ion extraction grid  45  may function to extract the ion beam  50  from the plasma  38 . The ion beam  50  sequentially passes through the second ion extraction apertures  41 H and the first ion extraction apertures  49 H to be injected into the specimen chamber  51 . 
     Generally, ions extracted from the plasma  38  may have a directionality perpendicular to the plasma surface  39 . As described above, in accordance with an exemplary embodiment of the present invention, it is possible to control the plasma surface  39  by adjusting the size of the second ion extraction apertures  41 H. That is, though the density of the plasma  38  is increased, the plasma surface  39  may be formed parallel to the surface of the plasma sheath controller  41  or  41 ′ opposite thereto. Therefore, it is possible to minimize collision of the ions extracted from the plasma  38  with the grid assembly  49  and scattering of the ions. 
     Eventually, it is possible to remarkably increase ion flux of the ion beam  50  compared to the conventional art by increasing the density of the plasma  38  and adjusting the size of the second ion extraction apertures  41 H. 
     Referring to  FIGS. 2 and 7 , the plasma sheath controller  41  or  41 ′ may be spaced apart from the grid assembly  49 . The grid assembly  49  may include the first ion extraction grid  43 , the insulating member  44 , and the second ion extraction grid  45 . 
     In this case, a gap region  41 G may be provided between the plasma sheath controller  41  or  41 ′ and the first ion extraction grid  43 . The gap region  41 G may be filled with an insulating material, but its description will be omitted for the sake of convenience. The gap region  41 G may have a sixth thickness T 6 . 
     The grid assembly  49  may include the first ion extraction apertures  49 H. The first ion extraction apertures  49 H may have a first width W 1 . The plasma sheath controller  41  or  41 ′ may include the second ion extraction apertures  41 H. The second ion extraction apertures  41 H may have a second width W 2 . The second width W 2  may be smaller than the first width W 1 . That is, the second ion extraction apertures  41 H may be smaller than the first ion extraction apertures  49 H. The plasma sheath controller  41  or  41 ′ may be a conductor or an insulator. 
     Generally, the plasma sheath  40  may exist between the plasma  38  and an object opposite thereto. That is, the plasma sheath  40  may exist between the plasma  38  and an insulator opposite to the plasma  38 . 
     Therefore, the plasma sheath  40  may exist between the plasma  38  and the plasma sheath controller  41  or  41 ′. The plasma sheath  40  may have a fifth thickness T 5 . The fifth thickness T 5  may vary depending on the density of the plasma  38 . For example, the higher the density of the plasma  38 , the thinner the fifth thickness T 5 . 
     The second width W 2  may be smaller than the fifth thickness T 5 . That is, the second ion extraction apertures  41 H may be smaller than the fifth thickness T 5  of the plasma sheath  40 . For example, the fifth thickness T 5  may be several times larger than the second width W 2 . When the second width W 2  is smaller than the fifth thickness T 5 , the plasma surface  39  may be formed parallel to the surface of the plasma sheath controller  41  or  41 ′ opposite thereto. 
     The first ion extraction grid  43  and the second ion extraction grid  45  may function to extract the ion beam  50  from the plasma  38 . The ion beam  50  sequentially passes through the second ion extraction apertures  41 H and the first ion extraction apertures  49 H to be injected into the specimen chamber  51 . 
     Ions extracted from the plasma  38  may have a directionality perpendicular to the plasma surface  39 . As described above, in accordance with an exemplary embodiment of the present invention, it is possible to control the plasma surface  39  by adjusting the size of the second ion extraction apertures  41 H. That is, though the density of the plasma  38  is increased, the plasma surface  39  may be formed parallel to the surface of the plasma sheath controller  41  or  41 ′ opposite thereto. Therefore, it is possible to minimize collision of the ions extracted from the plasma  38  with the grid assembly  49  and scattering of the ions. 
     Eventually, it is possible to remarkably increase ion flux of the ion beam  50  compared to the conventional art by increasing the density of the plasma  38  and adjusting the size of the second ion extraction apertures  41 H. 
     Referring to  FIGS. 2 and 8 , another grid assembly  49 ′ including the first ion extraction grid  43 , the insulating member  44 , the second ion extraction grid  45 , another insulating member  47 , and a third ion extraction grid  48  may be provided. The plasma sheath controller  41  or  41 ′ may be attached to the grid assembly  49 ′. Hereinafter, only differences therebetween will be described in brief. 
     The third ion extraction grid  48  may be interposed between the second ion extraction grid  45  and the specimen chamber  51 . In this case, the second ion extraction grid  45  may be interposed between the first ion extraction grid  43  and the third ion extraction grid  48 . The other insulating layer  47  may be interposed between the second ion extraction grid  45  and the third ion extraction grid  48 . The third ion extraction grid  48  may be a conductor. 
     The other grid assembly  49 ′ may include the first ion extraction apertures  49 H. The first ion extraction apertures  49 H may pass through the first ion extraction grid  43 , the insulating member  44 , the second ion extraction grid  45 , the other insulating member  47 , and the third ion extraction grid  48 . The first ion extraction apertures  49 H may have a first width W 1 . The first ion extraction grid  43 , the second ion extraction grid  45 , and the third ion extraction grid  48  may be arranged with reference to the first ion extraction apertures  49 H. 
     A voltage of the same polarity as the first ion extraction grid  43  may be applied to the third ion extraction grid  48 . In addition, a voltage lower than the first ion extraction grid  43  may be applied to the third ion extraction grid  48 . For example, when a first positive voltage is applied to the first ion extraction grid  43 , a second positive voltage is applied to the third ion extraction grid  48 , and the second voltage may be lower than the first voltage. 
     The first ion extraction grid  43 , the second ion extraction grid  45 , and the third ion extraction grid  48  may function to extract the ion beam  50  from the plasma  38 . The ion beam  50  sequentially passes through the second ion extraction apertures  41 H and the first ion extraction apertures  49 H to be injected into the specimen chamber  51 . Here, the third ion extraction grid  48  functions to control an acceleration speed of the ion beam  50  extracted through the first ion extraction apertures  49 H. 
     Generally, the ions extracted from the plasma  38  may have a directionality perpendicular to the plasma surface  39 . As described above, in accordance with an exemplary embodiment of the present invention, it is possible to control the plasma surface  39  by adjusting the size of the second ion extraction apertures  41 H. That is, though the density of the plasma  38  is increased, the plasma surface  39  may be formed parallel to the surface of the plasma sheath controller  41  or  41 ′ opposite thereto. Therefore, it is possible to minimize collision of the ions extracted from the plasma  38  with the grid assembly  49 ′ and scattering of the ions. 
     Eventually, it is possible to remarkably increase ion flux of the ion beam  50  compared to the conventional art by increasing the density of the plasma  38  and adjusting the size of the second ion extraction apertures  41 H. 
     EXAMPLE 
       FIG. 9  illustrates ion current characteristics measured in a first ion extraction grid in order to check variation of ion beams extracted by use of a plasma sheath controller, and  FIG. 10  illustrates ion current characteristics measured in a specimen chamber adjacent to a grid assembly in order to check variation of ion beams extracted by use of the plasma sheath controller. Horizontal axes P of  FIGS. 9 and 10  denote radio frequency (RF) power applied to an induction coil of a plasma chamber, and the unit is watt (W). Vertical axes Ic of  FIGS. 9 and 10  denote measured ion current, and the unit is micro ampere (μA). 
     A gas used in the experiment is argon (Ar). A grid assembly including a first ion extraction grid, a second ion extraction grid, and a third ion extraction grid was used. +150V, −100V and 0V were applied to the first ion extraction grid, the second ion extraction grid, and the third ion extraction grid, respectively. The grid assembly had first ion extraction apertures of 3.5 mm. A plasma sheath controller was attached to a surface of the first ion extraction grid. The plasma sheath controller was formed of a conductive net grid. 
     Referring to  FIG. 9 , curve  90  represents ion current characteristics measured in the first ion extraction grid when the plasma sheath controller was omitted and only the grid assembly was mounted. Curve  92  represents ion current characteristics measured in the first ion extraction grid when the plasma sheath controller having the second ion extraction apertures of 200 μm was mounted with the grid assembly. Curve  94  represents ion current characteristics measured in the first ion extraction grid when the plasma sheath controller having the second ion extraction apertures of 400 μm was mounted with the grid assembly. Curve  96  represents ion current characteristics measured in the first ion extraction grid when the plasma sheath controller having the second ion extraction apertures of 600 μm was mounted with the grid assembly. 
     As can be seen from curves  90 ,  92 ,  94  and  96 , it will be appreciated that the ion current measured in the first ion extraction grid is increased as the RF power applied to the induction coil of the plasma chamber is increased. That is, it will be appreciated that the ion current measured in the first ion extraction grid can be increased by an increase of the density of the plasma. 
     In addition, it is possible to relatively reduce the ion current measured in the first ion extraction grid by mounting the plasma sheath controller. That is, the ion current measured in the first ion extraction grid may be somewhat reduced due to installation of the plasma sheath controller. 
     Further, the smaller the size of the second ion extraction apertures, the less the ion current measured in the first ion extraction grid. That is, the ion current measured in the first ion extraction grid may be differently detected depending on the size of the second ion extraction apertures. It will also be appreciated that the ion current measured in the first ion extraction grid may be controlled by adjusting the size of the second ion extraction apertures. 
     Referring to  FIG. 10 , curve  110  represents ion current characteristics measured in the specimen chamber when the plasma sheath controller was omitted and only the grid assembly was mounted. Curve  112  represents ion current characteristics measured in the specimen chamber when the plasma sheath controller having the second ion extraction apertures of 200 μm was mounted with the grid assembly. Curve  114  represents ion current characteristics measured in the specimen chamber when the plasma sheath controller having the second ion extraction apertures of 400 μm was mounted with the grid assembly. Curve  116  represents ion current characteristics measured in the specimen chamber when the plasma sheath controller having the second ion extraction apertures of 600 μm was mounted with the grid assembly. 
     In curve  110 , when the plasma sheath controller was omitted and only the grid assembly was mounted, it will be appreciated that the ion current measured in the specimen chamber is somewhat reduced as the RF power is increased. It can be understood that the thickness of the plasma sheath is reduced due to increase of the plasma density and the ion flux is decreased due to dispersion of the extracted ions. 
     In curves  112 ,  114  and  116 , when the plasma sheath controller was mounted with the grid assembly, it will be appreciated that the ion current measured in the specimen chamber is increased as the RF power is increased. The ion current measured in the specimen chamber may be differently detected depending on the size of the second ion extraction apertures. In addition, it will be appreciated that the ion current measured in the specimen chamber may be controlled by adjusting the size of the second ion extraction apertures. 
     From  FIGS. 9 and 10 , it will be appreciated that an ion beam apparatus with high ion flux can be implemented by increasing the plasma density and using a plasma sheath controller and a grid assembly. 
     As can be seen from the foregoing, an ion beam apparatus having a plasma sheath controller and a grid assembly is provided. The plasma sheath controller functions to adjust formation of a plasma sheath. That is, a plasma surface can be provided parallel to the plasma sheath controller. Therefore, it is possible to implement an ion beam apparatus with high ion flux. In addition, it is possible to implement a semiconductor manufacturing apparatus using the ion beam apparatus with high ion flux. 
     Exemplary embodiments of the present invention have been disclosed herein and, although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. Accordingly, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.