Abstract:
An ion implanter and method for adjusting the shape of an ion beam are disclosed. After an ion beam is outputted from an analyzer magnet unit, at least one set of bar magnets is used to adjust the shape of the ion beam when the ion beam passes through a space enclosed by the bar magnets. The set of bar magnets can apply a multi-stage magnetic field on the ion beam. Hence, different portions of the ion beam will have different deformations or alterations, because the multi-stage magnetic field will apply a non-uniform force to change the trajectory of ions. Moreover, each bar magnet of the set is powered by one and only one power source, such that the set of bar magnets essentially only can adjust the magnitude of the multi-stage magnetic field. Particular structures and techniques for achieving the multi-stage magnetic field are not limited.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to ion implantation, and more particularly, to an ion implanter and a method for adjusting a shape of an ion beam with a simple mechanism and relatively low cost. 
     2. Description of the Prior Art 
     Ion implantation processes are widely used in semiconductor manufacture, for example, to implant wafers with various ions having desired energy. Ion implantation processes typically require a uniform and consistent amount of ions to be implanted into a semiconductor wafer. 
     A conventional ion implanter includes at least an ion source and an analyzer magnet unit (AMU). The ion source is used to generate an ion beam. The ion beam generated from the ion source is analyzed by the AMU before the required ions are implanted into a wafer. Although the ion beam is analyzed by the AMU, the shape (cross-sectional shape) of the ion beam usually is not perfect as required. For different applications, the shape required for the ion beam usually varies. Different implantation parameters usually correspond to different required shapes; for example, a spot-shape and a line-shape are used for different implantation parameters. 
     Some prior art devices achieve these different beam-shape requirements by amending the designs of the ion source and/or the AMU, such that ion beams outputted from the AMU can almost, even perfectly, have the required shapes. However, implementation of the technology is difficult, and usually requires a complex mechanism and a high cost. 
     On the other hand, some prior art devices achieve the beam-shape requirement by applying a magnetic field, or an electromagnetic field, to change the motion trajectories of ions, such that the shape of the ion beam  10  is changed. Here, after an ion beam is outputted from the AMU, the magnetic field is applied to further adjust the shape of the ion beam. As shown in  FIG. 1A , a conventional ion implanter typically includes an ion source  110 , an AMU  120 , a first bar magnet  131 , and a second bar magnet  132 . The ion beam  10  is generated by the ion source  110  and adjusted by the AMU  120  before it is injected into a wafer  20 . Herein, the first bar magnet  131  and the second bar magnet  132  are separately located on opposing sides of the trajectory of the ion beam  10  and used to adjust the shape of the ion beam  10 . 
       FIG. 1B  shows an example of the first bar magnet  131  and the second bar magnet  132  being located on opposite sides of the pre-determined trajectory of the ion beam  10 . Moreover, the first bar magnet  131  includes a first support rod  141  and a first winding coil  151 , and the second bar magnet  132  includes a second support rod  142  and a second winding coil  152 . Hence, when current I 1  and/or I 2  flows through the first bar magnet  131  and/or the second bar magnet  132  respectively, a magnetic field between the first bar magnet  131  and the second bar magnet  132  is generated which then affects the motion of ions. 
       FIG. 1C  shows how the shape of the ion beam  10  is affected by the magnetic field between the first bar magnet  131  and the second bar magnet  132 . As usual, the first winding coil  151  and the second winding coil  152  are uniformly distributed along the first support rod  141  and the second support rod  142 , respectively, such that a continuous magnetic filed is formed, whereby the ion beam  10  can then be adjusted. Herein, each of the first/second support rod  141 / 142  is usually distributed along a direction intersecting with the ion beam travel direction. For example, the rod can be distributed along a direction perpendicular to the ion beam travel direction. Moreover, the continuous magnetic field essentially is a single-stage magnetic field because both the magnitude and the direction of the continuous magnetic field are gradually varied without any back and forth variation. When the currents I 1  and I 2  are parallel as shown in  FIG. 1B , the magnetic fields generated by each bar magnet are generally opposite in direction in the space between the bar magnets. Significantly, the overall magnetic field contributed by both bar magnets points down near bar magnet  131 , points up near bar magnet  132 , points left toward magnet  131  in space below the center point, and points right toward bar magnet  132  in space above the center point. This is a typical quadrupole field. The quadrupole field can compress the ion beam in one direction and extend it in the other direction, depending on the relative direction between an ion beam and the bar magnets. When an ion beam  10  travels out of the paper in  FIG. 1C , and the currents I 1  and I 2  flow in the direction shown in  FIGS. 1B and 1C , the quadrupole field compresses the ion beam in the X direction and extends it in the Y direction, forming a beam narrower in the X direction and taller in the Y direction. When both currents I 1  and I 2  are reversed, the field extends the beam in the X direction and compresses it in the Y direction, forming a beam wider in the X direction and shorter in the Y direction. 
     However, for practical implantation requirements, the continuous magnetic field shown in  FIG. 1C  usually cannot effectively adjust the shape of the ion beam  10 . In short, it only can smoothly change the ion beam shape between spot-shape and line-shape, but cannot strongly deform the ion beam shape because the corresponding winding coil and the support rod can change only the magnitude of the continuous magnetic field. 
     Therefore, as shown in  FIG. 1D , yet another prior art approach was devised for adjusting the structure of both the first bar magnet  131  and the second bar magnet  132 . In this case, the first bar magnet  131  includes a first support rod  141  and a plurality of winding coils  151 / 153 / 155 . The winding coils  151 / 153 / 155  may be variably distributed along the first support rod  141 . The second bar magnet  132  includes a second support rod  142  and a plurality of winding coils  152 / 154 / 156 . The winding coils  152 / 154 / 156  also may be variably distributed along the second support rod  142 . Power sources  161 - 166  are electrically coupled with the winding coils  151 - 156  respectively. Hence, when the real position/length of each of the winding coils  151 - 156  is variable and the power sources  161 - 166  are independently operable, it is possible to induce a multi-stage magnetic field wherein both the magnitude and the direction of the continuous magnetic field can be gradually varied with at least one back and forth oscillation. Therefore, owing to the fact that different portions of the ion beam may be affected by different portions of the multi-stage magnetic field, the shape of different portions of the ion beam  10  can be independently adjusted. 
     However, for practical implantation requirements, the multi-stage magnetic field shown in  FIG. 1D  usually is too complex and expensive to be used. In short, to the extent winding coils  151 - 156  and power sources  161 - 166  are provided with different configurations and currents such that multi-stage magnetic fields can be induced, the total mechanism and its proper operation may be too complex. 
     Because of disadvantages associated with the prior art mentioned above, a need exists to propose a novel ion implanter and a novel method for adjusting an ion beam so as to effectively and economically adjust the shape of an ion beam without having to substantially modify the conventional ion implanter. 
     SUMMARY OF THE INVENTION 
     Accordingly, discovery has been made of the present invention, which is believed to meet such a need as described above by way of providing a novel ion implanter and method for effectively and economically adjusting the shape of an ion beam without requiring substantial or expensive changes to the conventional ion implanter. 
     As usual, for many practical ion implantation processes used in semiconductor manufacturing, the required variations in the shape of the ion beam are finite. Particularly, the combination of both the commercial ion source and the commercial analyzer magnet unit (AMU) usually can provide an ion beam with a real shape briefly similar to (e.g., about the same as) the required shape. Moreover, as usual, the ion beam shape is only a spot-shape and/or a line-shape, i.e., the cross-section of the ion beam usually is not polygon- and/or irregular-shaped. Therefore, according to a feature of the present invention, it is possible to achieve the required ion beam shape by adjusting only the magnitude of the magnetic field, which is being applied, in order to change the forces being applied on different portions of the ion beam. 
     The invention provides a method for adjusting the shape of an ion beam. After the ion beam is outputted from an AMU, at least one set of bar magnets is used to adjust the shape of the ion beam when the ion beam passes through a space enclosed by the bar magnets. Here, the set of bar magnets can apply a magnetic field of multiple stages (multi-stage magnetic field) on the ion beam. Hence, different portions of the ion beam will be differently deformed (e.g., altered) whereby the shape of the ion beam can be adjusted. Each bar magnet of the set is powered by one and only one power source, such that the set of bar magnets essentially can adjust only the magnitude of the multi-stage magnetic field. As disclosed herein, particulars on how the non-uniform magnetic field is provided are not intended to be limited. 
     The present invention also provides an ion implanter for adjusting an ion beam. The ion implanter includes an ion source, an AMU, and a first set of bar magnets. The ion source is capable of generating an ion beam, the AMU is capable of analyzing the ion beam, and the first set of bar magnets is capable of changing a shape of the ion beam after the ion beam is adjusted. The first set of bar magnets includes a first bar magnet and a second bar magnet, whereby at least one bar magnet set is capable of applying a multi-stage magnetic field on the analyzed ion beam when the analyzed ion beam passes through a space between the first bar magnet and the second bar magnet. 
     The present invention further provides another method for adjusting an ion beam. This method first prepares an ion implanter as mentioned above, and then adjusts at least one factor of a multi-stage magnetic field. Hence, at least the magnitude of the multi-stage magnetic field is adjusted to deform (e.g., alter) the shape of the ion beam. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a simplified diagram of a conventional ion implanter; 
         FIG. 1B  shows a magnetic field generated by a first bar magnet and a second bar magnet respectively; 
         FIG. 1C  shows how the shape of an ion beam is controlled by the magnetic field between the first bar magnet and the second bar magnet according to one prior-art construction; 
         FIG. 1D  shows how the shape of the ion beam is controlled by the magnetic field between the first bar magnet and the second bar magnet according to another prior-art construction; 
         FIG. 2A  shows a diagram of an ion implanter for adjusting an ion beam in accordance with an embodiment of the present invention; 
         FIG. 2B  shows a first embodiment of the first set of bar magnets shown in  FIG. 2A ; 
         FIG. 2C  shows a second embodiment of the first set of bar magnets shown in  FIG. 2A ; 
         FIG. 2D  shows a third embodiment of the first set of bar magnets shown in  FIG. 2A ; 
         FIG. 2E  shows a fourth embodiment of the first set of bar magnets shown in  FIG. 2A ; 
         FIG. 2F  shows a fifth embodiment of the first set of bar magnets shown in  FIG. 2A ; 
         FIG. 2G  shows a sixth embodiment of the first set of bar magnets shown in  FIG. 2A ; 
         FIG. 2H  shows a seventh embodiment of the first set of bar magnets shown in  FIG. 2A ; 
         FIG. 2I  shows a diagram of an ion implanter for adjusting an ion beam in accordance with another embodiment of the present invention; and 
         FIG. 3  shows a flow diagram of a method for adjusting an ion beam in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A detailed description of the present invention will be provided by way of the following embodiments, which are not intended to limit the scope of the present invention and which can be adapted for other applications. While the drawings are illustrated in detail, it is appreciated that the quantity of the disclosed components may be greater or less than that disclosed, except for instances expressly restricting the amount of the components. 
       FIG. 2A  shows a diagram of an ion implanter  200  for adjusting an ion beam  10  in accordance with an embodiment of the present invention. The ion implanter  200  includes an ion source  210 , an analyzer magnet unit (AMU)  220 , and a first set of bar magnets  230 . Here, the ion source  210  is capable of generating an ion beam  10 , the AMU  220  is capable of analyzing the ion beam  10 , and the first set of bar magnets  230  is capable of adjusting a shape of the ion beam  10  after the ion beam  10  is adjusted by the AMU  220 . 
     The first set of bar magnets  230  includes a first bar magnet  231  and a second bar magnet  232 . The first bar magnet  231  includes a first support rod  251  and a first continuous loop of winding coils  261  which is distributed along the first support rod  251 , and the second bar magnet  232  is located in a first preset distance D 1  from the first bar magnet  231 . The second bar magnet  232  likewise includes a second support rod  252  and a second continuous loop of winding coils  262  which is distributed along the second support rod  252 . Moreover, the ion implanter  200  also includes a first power source  271  and a second power source  272  which are electrically coupled with the first bar magnet  231  and the second bar magnet  232  respectively. Here, the operation of the first power source  271  can be independent or dependent on the operation of the second power source  272 . Particularly, at least one bar magnet  231 / 232  is capable of applying a magnetic field of multiple stages (multi-stage magnetic field) on the analyzed ion beam  10  when the analyzed ion beam  10  passes through a space between the first bar magnet  231  and the second bar magnet  232 . 
     One basic concept of the invention is using one and only one power source, such as  271  and  272 , to provide the current required by one bar magnet, such that only the magnitude of a multi-stage magnetic field induced by the bar magnet is changed. Also, another basic concept of the invention is using at least one non-uniform factor, such as different materials or different shapes, to induce the required multi-stage magnetic field for deforming (e.g., altering) a different portion of the ion beam. Furthermore, particulars on how to provide the power source, how to adjust the non-uniform factor(s) for adjusting the multi-stage magnetic field and the practical geometric configuration of the two bar magnets  231 / 232  are not intended to be limited in the invention. 
     Accordingly, by comparing  FIG. 2A  with both  FIG. 1C  and  FIG. 1D , the advantages of the invention are apparent and significant. First, the produced magnetic field is multi-stage rather than a single-stage magnetic field as shown in  FIG. 1C , such that the disadvantages of the prior art shown in  FIG. 1C  can be effectively improved. Next, there is one and only one power source for providing the current required by one bar magnet; hence, the complexity of the prior art structure shown in  FIG. 1D  is effectively avoided. Here, it should be noted that the direction of the first set of bar magnets  230  is not particularly limited. It can be changed to adjust the projection of the ion beam on the wafer  20  to be implanted. 
       FIG. 2B  shows a first embodiment of the first set of bar magnets  230  shown in  FIG. 2A . The first continuous loop of winding coils  261  includes a plurality of sections  2611 - 2613 , wherein at least two different ones of the sections  2611 - 2613  have a different density of coils or coil density (turns/mm). That is, the coil density is the number of coils per unit length. Besides, the second continuous loop of winding coils  262  also includes a plurality of sections  2621 - 2623 , wherein at least two different ones of the sections  2621 - 2623  have different coil density (turns/mm). Herein, the first continuous loop of winding coils  261  and the second continuous loop of winding coils  262  are non-uniformly distributed along the first support rod  251  and the second support rod  252  respectively. 
     In this embodiment, the distribution of the first continuous loop of winding coils  261  along the first support rod  251  is essentially similar to (e.g., about the same as) the distribution of the second continuous loop of winding coils  262  along the second support rod  252 . Such design can simplify the calculation and the control of the non-uniform magnetic field. However, the invention allows for different continuous loops of winding coils having different distributions. Moreover, although  FIG. 2B  shows two non-uniform continuous loops of similar winding coils  261 / 262 , the invention allows for one set of continuous loops of winding coils  261  and  262  to be non-uniform but different, and also allows for only one (e.g., one of the) set of continuous loops of winding coils  261 / 262  to be non-uniform. 
     The direction of current I 1  flow through the first bar magnet  231  is essentially parallel to the direction of current I 2  flow through the second bar magnet  232 , such that the ion beam  10  is compressed in a first direction X and extended in a second direction Y which is essentially vertical to the first direction X. Moreover, by at least changing the magnitudes and alternating the directions of both currents I 1  and I 2 , the distribution of the multi-stage magnetic field appearing is changeable, such that the shape of the ion beam  10  can be reasonably adjusted. 
       FIG. 2C  shows a second embodiment of the first set of bar magnets  230  shown in  FIG. 2A . The first continuous loop of winding coils  261  includes a plurality of sections  2611 - 2613 , wherein at least two different ones of the sections  2611 - 2613  have different inductor coefficients, such as can be achieved from fabrication thereof from different materials. Moreover, the second continuous loop of winding coils  262  can also include a plurality of sections  2621 - 2623 , wherein at least two different ones of the sections  2621 - 2623  have different inductor coefficients, such as by construction from different materials. 
     Again, the first set of bar magnets  230  can have only one continuous loop of winding coils being made of a different material with the other continuous loops of winding coils being made of the same material. Herein, different inductor coefficients will change power through the coils thereby slightly changing the diameters (e.g., via expansion) of the coils, such that a non-uniform magnetic field will be induced. Significantly, other differences of different materials also can be factors of inducing different (non-uniform) magnetic fields. For example, different thermal expansion coefficients can be implemented to change the diameter of each coil, such that the length of each winding coil is changed whereby the induced magnetic field also is correspondingly altered. 
       FIG. 2D  shows a third embodiment of the first set of bar magnets  230  shown in  FIG. 2A . The second support rod  252  is not straight and includes a plurality of sections  2521 - 2522 , wherein at least two different ones of the sections  2521 - 2522  have different directions. Of course, the first support rod  251  also can be non-straight. 
     Clearly, when the distance between two support rods  251 / 252 , or the distance between two continuous loops of winding coils  261 / 262 , is varied along the direction of any support rod  251 / 252 , the magnetic field distributed between the two support rods  252 / 252  will have multi-stages whereby the shape of the ion beam  10  will then be correspondingly adjusted. 
       FIG. 2E  shows a fourth embodiment of the first set of bar magnets  230  shown in  FIG. 2A . The first support rod  251  includes a plurality of sections  2511 - 2513 , wherein at least two different ones of the sections  2521 - 2522  have different width. At least two different sections of the second continuous loop of winding coils  261  can also have different width. Moreover, the second support rod  252  also includes a plurality of sections  2521 - 2523 , wherein at least two different ones of the sections  2521 - 2522  have different width, and at least two different sections of the first continuous loop of winding coils  261  can also have different width. 
     Clearly, if any support rod is made of an electromagnetic conductor, different widths of different sections of any support rod will change the distribution of an induced magnetic field. Moreover, if a continuous loop of winding coils is attached on a support rod, different widths of different sections of a support rod will change the distribution of the continuous loop of winding coils. Hence, the distribution of magnetic field along the direction of each support rod  251 / 252  will be multi-stage, whereby the shape of the ion beam  10  can then be adjusted when at least the magnitude of the magnetic field can be adjusted by changing the widths of at least two sections of the support rod. 
       FIG. 2F  shows a fifth embodiment of the first set of bar magnets  230  shown in  FIG. 2A . The first support rod  251  includes a plurality of sections  2511 - 2513 , wherein at least two different ones of the sections  2511 - 2512  are made of different material. Besides, the second support rod  252  also includes a plurality of sections  2521 - 2523 , wherein at least two different ones of the sections  2521 - 2522  are made of different material. 
     Clearly, the embodiment is similar to the embodiment shown in  FIG. 2C ; the only difference is which portions are made of different materials. However, regardless of whether/how the support rod(s)  251 / 252  are made of different materials and/or the winding coils  261 / 262  are made of different materials, the corresponding magnetic field may be multi-stage between the two support rods  251 / 252  (or two bar magnets  231 / 232 .) 
       FIG. 2G  shows a sixth embodiment of the first set of bar magnets  230  shown in  FIG. 2A . At least one section of the first support rod  251  is located close to a conductive structure  291 - 292  and at least one section of the first support rod  251  is not located close to any conductive structure  291 - 292 . Besides, at least one section of the second support rod  252  is also located close to a conductive structure  293 - 294 , and at least one section of the second support rod  252  is not located close to any conductive structure  293 - 294 . 
       FIG. 2H  shows a seventh embodiment of the first set of bar magnets  230  shown in  FIG. 2A . Different sections of the first support rod  251  are located close to different conductive structures  291 - 293 , wherein each section and a corresponding one of the conductive structures  291 - 293  has an individual relative position. Different sections of the second support rod  252  are also located close to different conductive structures  294 - 296 , wherein each section and a corresponding one of the conductive structures  294 - 296  has an individual relative position. 
     Clearly, in the two previous embodiments, the existence of the conductive structure(s) will change the distribution of magnetic fields, even when the conductive structure(s) is not located directly between the two support rods  251 / 252  (or the bar magnets  231 / 232 ). Again, the shape of the ion beam  10  can be adjusted by the change on the distribution of magnetic field. 
     According to the above embodiments, the multi-stage magnetic field of the first set of bar magnets  230  can be induced by many non-uniform factors. For example, the shape of the magnetic field of the first set of bar magnets  230  can be adjusted by changing one or more of the following factors: the number of coils per unit length of the coils  261 / 262 , the materials used to form the coils  261 / 262 , the materials used to form the support rod  251 / 252  to which the coils  261 / 262  are attached, the shape of the support rod  251 / 252 , and the shape of the coils  261 / 262 . The shape of the magnetic field of the first set of bar magnets  230  can also be adjusted by changing the first preset distance D 1  which is between the first bar magnet  231  and the second bar magnet  232  (such change is not shown in the figure). 
       FIG. 2I  shows another embodiment where the ion implanter  200  further includes a second set of bar magnets  240  which is also capable of changing the shape of the ion beam  10  after the ion beam  10  is adjusted by the AMU  220 . The second set of bar magnets  240  is located in a second preset distance D 2  from the first set of bar magnets  230 . The second set of bar magnets  240  includes a third bar magnet  241  and a fourth bar magnet  242 . The third bar magnet  241  includes a third support rod  253  and a third continuous loop of winding coils  263  which is distributed along the third support rod  253 . The fourth bar magnet  242  is located in a third preset distance D 3  from the third bar magnet  241 . The fourth bar magnet  242  includes a fourth support rod  254  and a fourth continuous loop of winding coils  264  which is distributed along the fourth support rod  254 . The ion implanter  200  can also include a third power source  273  which is electrically coupled with both the third continuous loop of winding coils  263  and the fourth continuous loop of winding coils  264 . The distribution of the third continuous loop of winding coils  263  along the third support rod  253  can be essentially similar to (e.g., about the same as) the distribution of the fourth continuous loop of winding coils  264  along the fourth support rod  254 . The third continuous loop of winding coils  263  is essentially parallel to the fourth continuous loop of winding coils  264 , such that the ion beam  10  is compressed (or extended) in a first direction X and extended (or compressed) in a second direction Y which is essentially vertical to the first direction X. 
     Clearly, when the third and/or fourth bar magnets  241 / 242  has one or more of the factors mentioned above, the second set of bar magnets  240  is essentially similar to (e.g., about the same as) the first set of bar magnets  230 . In other words, two proposed sets of bar magnets are used to adjust the shape of the ion beam in sequence. 
     In contrast, when the third and fourth continuous loops of winding coils  263 / 264  are uniformly distributed, the second set of bar magnets  240  is essentially similar to (e.g., about the same as) the prior art shown in  FIG. 1C . In other words, the proposed set of bar magnets is combined with the prior art shown in  FIG. 1C  to adjust the shape of the ion beam in sequence. 
     Clearly, if the power source  273  is replaced by several power sources to respectively supply current to different portions of the third and fourth continuous loops of winding coils  263 / 264 , the second set of bar magnets  240  is essentially similar to (e.g., about the same as) the prior art shown in  FIG. 1D . In other words, the proposed set of bar magnets is combined with the prior art shown in  FIG. 1D  to adjust the shape of the ion beam in sequence. 
     Accordingly, any type of bar magnets can be positioned between the AMU  220  and the first set of bar magnets  230 , or between the first set of bar magnets  230  and the wafer  20  to further deform (e.g., alter) the shape of the ion beam. Herein, owing to each bar magnet being able to adjust the shape of the ion beam  10  independently, the locations of these bar magnets along a predetermined trajectory of the ion beam  10  are flexible. 
     Of course, when more than one bar magnet is used, each bar magnet can have its individual direction. Then, different portions of the ion beam  10  can be respectively adjusted by different bar magnets, such that a complete deformation (e.g., alteration) of the ion beam  10  is achieved by more than one single and simple deformation (e.g., alteration) of the ion beam  10 . 
     Note that the support rod is optional and not necessary. As usual, a support rod is essentially used to fix a corresponding continuous loop of winding coils, and further used to enhance the induced magnetic field when the support rod is made of an electromagnetic conductor, such as a ferromagnetic material. However, if the structure of the continuous loop of winding coils is strong enough, the support rod can be omitted if it is only used as a support. 
     Accordingly, by using the proposed ion implanter  200 , the shape of the ion beam  10  can be effectively adjusted. Moreover, when only the preexisting (e.g., used) power source(s) and the preexisting (e.g., used) bar magnets are modified to provide a multi-stage magnetic field, the invention can be achieved without strongly amending (e.g., significantly altering) the conventional ion implanter. 
       FIG. 3  shows a flow diagram of a method  300  for adjusting an ion beam in accordance with an embodiment of the present invention. The method  300  includes two essential steps  310  and  320 . First, as shown in block  310 , prepare an ion implanter with a set of bar magnets capable of inducing a multi-stage magnetic field as mentioned above. Then, as shown in block  320 , adjust the factors of forming a multi-stage magnetic field as mentioned above, such that at least the magnitude of the multi-stage magnetic field is changed whereby the ion beam is then deformed (e.g., altered) accordingly. 
     Herein, owing to the details of the ion implanter  200  being equal to those of the embodiments mentioned above, the details and potential variations of the ion implanter  200  are omitted. 
     Clearly, when the power source is turned off, i.e., there is no current passing through the continuous loop of winding coils, it is easy to change these factors. In other words, the method can be used to manufacture a new ion implanter, and also can be used to adjust an in-use ion implanter when it is maintained. 
     Of course, if any of these factors can be adjusted when the power source is turned on, i.e., there is a current passing through the continuous loop of winding coils, the method can be used even to adjust an ion implanter during the operation of the ion implanter. 
     In practice, it may be difficult to change coil shape and rod material during ion implanter operation. However, it is possible to choose any method above to provide a magnetic field to match a specific ion beam shape from an ion source. Hence, the method only needs to adjust the magnetic field magnitude to provide proper ion beam shape. 
     Although specific embodiments have been illustrated and described, it will be appreciated by those skilled in the art that various modifications may be made without departing from the scope of the present invention, which is intended to be limited solely by the appended claims.