Abstract:
An electrode adjustment method and apparatus are disclosed for use in workpiece processing. The assembly may include an electrode assembly having first and second ends. First and second manipulators may be coupled to the first and second ends. The manipulators may be used to selectively impart movement to the first and second ends of the electrode assembly to adjust one or more properties of an ion beam passing through the electrodes. The first and second manipulators may be independently actuatable so that the first and second ends of the electrode can be adjusted independent of one another. Methods of using the disclosed apparatus are also disclosed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a non-provisional of pending U.S. provisional patent application Ser. No. 61/625,428 filed Apr. 17, 2012, the entirety of which application is incorporated by reference herein. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    Embodiments of the invention relate to semiconductor processing in general and in particular to systems and methods for manipulating an electrode assembly in relation to semiconductor processing applications. 
         [0004]    2. Discussion of Related Art 
         [0005]    Ion implantation is a process of introducing chemical species into a workpiece by bombardment of the workpiece with energized ions. In semiconductor manufacturing, ion implanters are used for doping processes that alter the type and level of conductivity of target materials. A precise doping profile in a workpiece, such as an integrated circuit (IC) substrate, and its thin-film structure is important for proper IC performance. To achieve a desired doping profile, one or more ion species may be implanted in different doses and at different energy levels. 
         [0006]      FIG. 1  depicts an ion implanter system. The ion implanter  100  includes a an ion source  101 , an electrode assembly  102  including a plurality of electrodes, and a plurality of beamline components  103  for manipulating ion energies and to cause an ion beam  10  to hit a target workpiece  114  at a desired energy. 
         [0007]    As noted, ion implanters use electrodes to manipulate ion energies (i.e., guide, accelerate, or decelerate the ions in an ion beam). For example, the plurality of electrodes  104  may be used to extract and form an ion beam from an ion source. The position of these electrodes may need to be adjusted to account for changes in ion beam energy or ion beam current. The orientation of these electrodes also may need to be adjusted to correct for mechanical misalignments or to change the ion beam direction. As electrodes become larger or as ion beams increase in size, it becomes more challenging to support the electrodes at a single end. There is a need, therefore, for an improved device to adjust the position of large electrodes in an ion implanter to maintain a desired uniform ion beam. 
       SUMMARY OF THE INVENTION 
       [0008]    This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Description of Embodiments. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended as an aid in determining the scope of the claimed subject matter. 
         [0009]    An electrode adjustment assembly is disclosed for use in workpiece processing. The assembly may include an electrode having first and second ends, a first manipulator coupled to the first end, and a second manipulator coupled to the second end. The first and second manipulators may be configured to selectively impart movement to the first and second ends of the electrode. The first and second manipulators may be independently actuatable so that the first and second ends of the electrode can be adjusted independent of one another. 
         [0010]    An electrode adjustment assembly is disclosed for use in workpiece processing. The assembly may include an electrode assembly having first and second ends, a first manipulator coupled to the first end and a second manipulator coupled to the second end. The first and second manipulators may be configured to selectively and independently impart movement to the first and second ends of the electrode assembly. 
         [0011]    A method is disclosed for adjusting an electrode as part of a workpiece processing operation. The method may comprise: adjusting first and second ends of an electrode using first and second independently controllable manipulators associated with the first and second ends, respectively, wherein adjusting the first and second ends adjusts a parameter of an ion beam received through an aperture in the electrode. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The accompanying drawings illustrate preferred embodiments of the disclosed method so far devised for the practical application of the principles thereof, and in which: 
           [0013]      FIG. 1  is a schematic illustration of an exemplary ion implant system; 
           [0014]      FIG. 2  is an isometric view of a source chamber assembly of the system of  FIG. 1 ; 
           [0015]      FIG. 3  is a cross-section view of the source chamber assembly of  FIG. 2  taken along line  3 - 3 ; 
           [0016]      FIG. 4  is an isometric view of an embodiment of a suppression-ground electrode assembly portion of the source chamber assembly of  FIG. 2 ; 
           [0017]      FIG. 5  is an isometric view of a portion of the suppression-ground electrode assembly of  FIG. 4 ; 
           [0018]      FIG. 6  is an alternative first side view the portion of the suppression-ground electrode assembly of  FIG. 5  in which the assembly is rotated about a first axis; 
           [0019]      FIG. 7  is an alternative second side view the portion of the suppression-ground electrode assembly of  FIG. 5  in which the assembly is rotated about a second axis; 
           [0020]      FIG. 8  is an isometric view of an exemplary manipulator of the suppression-ground electrode assembly of  FIG. 4 ; 
           [0021]      FIG. 9  is an isometric view of a seal plate assembly of the suppression-ground electrode assembly of  FIG. 4 ; 
           [0022]      FIG. 10  is a reverse isometric view of the seal plate assembly of  FIG. 9 ; 
           [0023]      FIGS. 11-14  are a series of cross-section views of the of the suppression-ground electrode assembly of  FIG. 2 , taken along line  11 - 11  of  FIG. 2 , showing various positioning of the source and ground electrodes using a pair of manipulators; and 
           [0024]      FIG. 15  is a flowchart illustrating an exemplary method according to the disclosure. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0025]    The embodiments are described herein in connection with an ion implanter. This ion implanter may be a beam-line ion implanter that mass analyzes the ion beam or a flood implanter that does not mass analyze the ion beam. However, these embodiments also can be used with other systems and processes involved in semiconductor manufacturing or other systems that use ions. These embodiments may be used in an implanter for flat panels, semiconductor or IC substrates, solar cells, or other workpieces. Thus, the invention is not limited to the specific embodiments described below. 
         [0026]      FIGS. 2 and 3  show an exemplary source chamber assembly  120  which may include a chamber portion  122  and a suppression/ground electrode assembly (“electrode assembly”)  124 . As will be appreciated, the interior of the chamber portion  122  and the electrode assembly  124  will be subject to high vacuum conditions during operation, while the outside of the chamber portion  122  will be exposed to ambient conditions. The electrode assembly  124  has first and second ends  126 ,  128  coupled to first and second manipulators  130 ,  132  positioned outside of the chamber portion  122 . As will be described in greater detail later, the manipulators  130 ,  132  can be used to adjust the position of the first and second ends  126 ,  128  of the electrode assembly  124  in order to adjust one or more properties of the ion beam  10  ( FIG. 1 ) passing there through in the direction of arrow “Z”. 
         [0027]      FIG. 4  shows the electrode assembly  124  and first and second manipulators  130 ,  132  disassociated from the chamber portion  122 . Visible in this view are first and second actuation arm assemblies  134 ,  136  that couple the first and second manipulators  130 ,  132  to respective first and second ends  126 ,  128  of the electrode assembly  124 . As previously noted the electrode assembly  124  is disposed inside the chamber portion  122  and is exposed to high vacuum conditions. The first and second manipulators  130 ,  132  are outside the chamber portion  122  and are exposed to ambient conditions. Since the first and second actuation arm assemblies  134 ,  136  must penetrate the chamber portion  122 , first and second seal plates  138 ,  140  are positioned between the manipulators  130 ,  132  and the outer surface of the chamber portion  122  to prevent ambient air or other contaminants from entering the interior of the chamber portion  122  through the penetrations during operation. 
         [0028]      FIG. 5  shows the interconnection between the first manipulator  130  and the first end  126  of the electrode assembly  124  in greater detail. Although the description will proceed in relation to the first end of the assembly, it will be appreciated that the description will apply equally to the interconnection between the second manipulator  132  and the second end  128  of the electrode assembly. As can be seen, the first manipulator  130  is coupled to the first end  126  of the electrode assembly  124  via the first actuation arm assembly  134 . The actuation arm assembly  134  may include a manipulator rod  142  configured to engage the first manipulator  130 . The manipulator rod  142  may be coupled to a collar  144  which may slidably receive the rod. The collar  144  may be connected to an arm portion  146  which, in the illustrated embodiment, has a curved geometry that enables the arm portion to extend around a distal end  126   a  of the electrode assembly  124  to connect to the electrode assembly on a side opposite that of the incoming ion beam  10  ( FIG. 3 ). In this way, a portion of the actuation arm assembly  134  is shielded from the ion beam by the first end  126  of the electrode assembly. 
         [0029]    The arm portion  146  may be fixed to a first pivot block  148 . The first pivot block  148  may be pivotably coupled to a second pivot block  150  via a first pin connection  152  so that the first and second pivot blocks are rotatable with respect to each other about axis “X-X.” In one embodiment, axis “X-X” is aligned with a short dimension of the ion beam  10 . The second pivot block  150  may be pivotably coupled to a mounting bracket  154  via a second pin connection  156  so that the second pivot block and the mounting bracket  154  are rotatable with respect to each other about axis “Z-Z.” In one embodiment, axis “Z-Z” is aligned with the travel direction of the ion beam  10  (arrow Z in  FIG. 3 ) and is orthogonal to the axis “X-X”. Thus arranged, the electrode assembly  124  and the first manipulator  130  are rotatable with respect to each other about two mutually perpendicular axes. It will be appreciated that this arrangement is not limiting, and the pivot blocks may be arranged so that fewer or greater degrees of freedom are provided. Further, where multiple degrees of freedom are provided, they need not be orthogonally related. 
         [0030]    It will be appreciated that the suppression electrode of the electrode assembly  124  may be maintained at a high voltage during operation, while the manipulator  130  may be held at ground potential. As such, a plurality of insulators  158  may be coupled between the mounting bracket  154  and the first end  126  of the electrode assembly. 
         [0031]    As described, the electrode assembly  124  can pivot with respect to the manipulator  130  about the “X-X” and “Z-Z” axes. The assembly  124  may also be adjustable along the “Y-Y” axis ( FIG. 7 ) via sliding movement between the manipulator rod  142  and collar  144  of the actuation arm assembly  134 . In one embodiment, the “Y-Y” axis is aligned with a long dimension of the ion beam  10 . A set screw  160  may be disposed in an opening in the collar  144  such that a tip of the screw engages the rod  142  to lock the two in position once a desired “Y” position of the electrode assembly  124  is obtained. This can be done in an initial manual adjustment step in which a user can physically manipulate the “Y” position of the electrode assembly  124  to obtain a desired position of the electrodes with respect to the beam  10 . It will be appreciated, however, that the “Y” position of the electrode assembly could be automatically controlled by providing an appropriate adjustment mechanism as part of the manipulator  130 . 
         [0032]    In operation, the electrode assembly  124  will undergo thermal expansion in the “Y-Y” direction. Thus, the set screw  160  associated with the first manipulator  130  may be used to lock the rod  142  and collar  144  together, while the set screw associated with the second manipulator  132  may be eliminated (or not engaged with the rod) so as to allow the rod to slide within the collar to accommodate expansion of the assembly during operation. 
         [0033]      FIGS. 6 and 7  show exemplary movement modes of the electrode assembly  124  via the pin connections  154 ,  156 .  FIG. 6  illustrates the first end  126  of the electrode assembly  124  rotating about the “Z-Z” axis via second pin connection  156 . This motion may be induced via the movement of the manipulator rod  142  in the direction of arrow “A,” which is aligned with the “X-X” axis ( FIG. 5 ).  FIG. 9  illustrates the first end  126  of the electrode assembly  124  rotating about the “X-X” axis via first pin connection  154 . This motion may be induced via the movement of the manipulator rod  142  in the direction of arrow “B,” which is aligned with the “Z-Z” axis ( FIG. 5 ). 
         [0034]    As will be appreciated, a wide range of positions of the electrode assembly  124  may be achieved through relative movement of the first and second ends  126 ,  128  of the electrode assembly  124  using the first and second manipulators  130 ,  132  and the first and second pin connections  154 ,  156 . By moving of the electrode assembly  124  in such a manner, adjustments can be made to one or more properties of the ion beam  10 , such as beam current level, beam current uniformity, and the like. Where beam current parameters are measured before, during or after an implant process, and where one or more parameters fall outside a predetermined range, the ion beam may be re-tuned by adjusting the position of the electrode assembly  124  using the manipulators. 
         [0035]      FIG. 8  shows the components of the first manipulator  130 . It will be appreciated that the following description will apply equally to the first and second manipulators  130 ,  132 . The manipulator  130  may include a base plate  161  upon which a slide table  162  is mounted for movement thereon. The slide table  162  may include a rod receiving collar  164  having an opening  166  for receiving an end of the manipulator rod  142  so that a desired motion may be imparted to the rod and, in turn, the first end  126  of the electrode assembly  124 . The slide table  162  may be positioned for movement with respect to the base plate  161  in two mutually orthogonal directions, indicated by arrows “A” and “B.” In the illustrated embodiment, movement of the slide table  162  along arrow “A” results in movement of the first end  126  in a direction parallel to the “X-X” axis ( FIG. 6 ), while movement along arrow “B” results in movement of the first end  126  in a direction parallel to the “Z-Z” axis ( FIG. 5 ). 
         [0036]    The slide table  162  may be moved back and forth on the base plate  161  via first and second actuators  168 ,  170 . In the illustrated embodiment, the first and second actuators  168 ,  170  comprise first and second servomotors  172 ,  174  coupled to respective screws  176 ,  178 . The screws  176 ,  178  are received by correspondingly threaded openings in first and second flanges  180 ,  182  connected to the slide table. As will be understood, actuation of the servomotors  172 ,  174  causes respective belt/pulley arrangements  184 ,  186  to rotate the associated screw  176 ,  178 . Since the screws  176 ,  178  are axially fixed to respective motor brackets  187 ,  188  (which themselves are fixed to the base plate  161 ), rotation of the screws  176 ,  178  causes movement of the respective flange  180 ,  182  via the threaded interaction between the screw threads and the threads in the flange openings. Movement of the flanges  180 ,  182  causes movement of the slide table  162  on the base plate  161 , which, in turn, may move the manipulator rod  142  by a desired amount. It will be appreciated that the first and second actuators  168 ,  170  may be controlled by entering coordinates for motion in “A” and “B” directions that will improve or degrade one or more conditions or properties of the ion beam  10 . Incremental adjustments can be made in both axes until desired beam specifications are achieved. The first and second actuators  168 ,  170  can be independently adjustable to provide a desired movement of the manipulator rod  142 . 
         [0037]    In the illustrated embodiment, first and second optical sensors  189 ,  191  are positioned adjacent to the slide table  162  to provide verification of the position of the slide table  162  with respect to the base plate  161 . These optical sensors  189 ,  191  may read the position of a calibrated tape positioned on the slide table  162  to determine position. This information may be provided to a control system (not shown) for use in controlling the position of the electrode assembly  124 . 
         [0038]      FIGS. 9 and 10  show an embodiment of the first seal plate  138  for sealing the associated manipulator  130  to the chamber portion  122  of the electrode assembly  124 . Once again, it will be appreciated that the description will apply equally to the second seal plate  140 . The seal plate  138  may have an opening  188  for receiving the manipulator rod  142  there through. A plurality of grooves  190   a, b , and  c  may surround the opening  188  to provide a seal against the ingress of air or other gas into the chamber portion  122  during operation. In the illustrated embodiments, the grooves  190   a, b, c  are not symmetric about the opening  188 . The differentially spaced gaps allow for relative motion between adjacent plates and their respective openings to enable differential pumping of two stages between atmospheric pressure and high vacuum conditions within the chamber portion  122 , as will be described in greater detail below. Although not shown, elastomeric o-rings may be disposed in each of the grooves  190   a, b, c.    
         [0039]    The grooves  190   a, b, c  together may comprise a differential pumping region in which the grooves  190   a, b, c  are coupled to openings (not shown) in the base plate  161  of the manipulator, or in an intermediate plate (not shown). The openings may be coupled to a suction source via tube connections  192 ,  194  (see  FIG. 8 ) so as to draw gas out through the grooves  190   a, b , and  c . Thus, any air or other gas traveling from the ambient and/or between the seal plate  138  and the chamber portion  122  will be drawn out between the grooves  190   a, b, c  or seals before reaching the interior of the chamber portion, thus minimizing or eliminating entry of gas from the air bearing or the ambient atmosphere to the chamber portion. 
         [0040]    An intermediate sealing plate  192  may also be provided between the seal plate  138  and the base plate  161 . This intermediate sealing plate  192  can best be seen in  FIG. 10 . The intermediate sealing plate  192  may also have an opening  194  for receiving the manipulator rod  142  there through. Although not shown, the intermediate sealing plate  192  may include a plurality of pumped grooves similar to those previously described in relation to the seal plate  138  to minimize the chance for ingress of air or other contaminants into the chamber portion  122  during operation. These pumped grooves may be connected to a suction source (e.g., via tube connections  192 ,  194 ) to draw air or other gases out through the grooves before they reach the interior of the chamber portion. 
         [0041]    It will be appreciated that although the illustrated embodiment employs a differential pumping arrangement to seal the process chamber from the ambient and the air bearing, other sealing arrangements could be used. For example, one or more lip seal arrangements could be used in lieu of, or in addition to, the series of pumped grooves. In addition, greater or fewer than three grooves could be used, as desired. 
         [0042]    Referring now to  FIGS. 11-15 , a variety of positioning of the electrode assembly  124  is shown. It will be appreciated that these positioning can be achieved using the manipulators  130 ,  132  ( FIG. 2 ). In addition, although these discrete positioning of the electrode assembly  124  are shown, it will be appreciated that a wide variety of other positioning can also be achieved using the disclosed arrangement. These views show a cross-section of the electrode assembly  124  looking down at the second adjustment arm assembly  136 .  FIG. 11  shows the relative position of the ground electrode  196 , the suppression electrode  198  and the extraction electrode  200 . As previously noted, the ground and suppression electrodes  196 ,  198  may together make up the electrode assembly  124 , and thus the position of these electrodes can be manipulated with respect to the extraction electrode  200  and the ion beam  10  which is shown passing through a gap slot  202 . Also shown in this view is a magnetic suppression plate  204  configured to prevent ions from streaming back toward the electrode assembly  124 . As can be seen, the electrode assembly  124  has been adjusted so that the slots  206 ,  208  of the ground and suppression electrodes are slightly off-center with respect to the gap slot  202  of the extraction electrode  200 .  FIG. 12  shows the electrode assembly  124  shifted in the direction of arrow “A,” which is parallel to the “X-X” axis shown in  FIG. 5 . In this position, the slots  206 ,  208  of this portion of the assembly align with the gap slot  202  of the extraction electrode.  FIG. 13  shows the electrode assembly  124  shifted in the direction of arrow “B,” which is parallel (and opposite) to the direction of the ion beam  10  and to the axis Z-Z ( FIG. 5 ), thus bringing the illustrated portion of the assembly closer to the extraction electrode  200 .  FIG. 14  shows yet further adjustment of the electrode assembly  124  in the direction of arrow “B,” bringing the assembly even closer to the extraction electrode  200 . 
         [0043]    This alignment between the electrodes and their respective gaps, along with other beam control elements, will dictate the transmission of ions via the ion beam  10  to a workpiece (i.e., flat panel or semiconductor substrate). Different ions and implanted depths (also referred to as “recipes”) require different optimized positions. The range of movement along each axis imparted by the manipulators can, in some embodiments, be sufficient to cover all desired recipes. 
         [0044]    The extraction, suppression and ground electrodes can be pre-aligned using any of a variety of appropriate fixtures in order to acquire “0 positions” for all axes of both manipulators. The goal is to provide a home position in two directions for the manipulators to start and return to when power is lost or shut down intentionally. 
         [0045]    In some embodiments movements of +7.5 mm along the X-X axis and +18 mm along the Z-Z axis are facilitated, though other movement amounts are possible. The manipulators  130 ,  132  may be configured to support the weight of the electrode assembly  124 , where such an assembly has weight and dimensions that accommodate an ion beam for large workpieces, such as flat panels. 
         [0046]    As will be appreciated, the use of a pair of manipulators  130 ,  132  enables multiple modes of movement. First, the manipulators may move together in the same direction to adjust the entire electrode assembly  124  along the X-X and/or Z-Z axis. In some embodiments, motion along the X-X and/or Z-Z axis may be adjusted during setup and calibration of the system or during recipe creation and beam tuning Small values of Z-Z axis movement (i.e., moving the suppression and ground electrodes are closer to the front plate of the ion source) are generally desirable when higher ion beam currents are extracted or when the ion beam energy is lower. Adjustments along the X-X axis may typically correct for beam misalignment. 
         [0047]    The manipulators  130 ,  132  may also move in opposite directions, which leave the center of the electrode assembly  124  stationary while the first and second ends  126 ,  128  of the electrode assembly move in opposite directions with respect to this center. Such movement may correct for misalignment of the electrode assembly  124 . 
         [0048]    Further, one or both of the manipulators  130 ,  132  may adjust along the X-X and/or Z-Z axes, which may be referred to as adjusting ΔX or ΔZ. ΔX and ΔZ may be used during beam tuning to correct for misalignment. The misalignment may manifest as high current on the suppression electrode power supply, lower overall transmitted ion beam current through the system, or as a non-uniform ion beam current as a function of position along the ribbon ion beam. Mechanical misalignments typically happen due to assembly error, limits on fabrication accuracy, or from thermal expansion of the components due to elevated temperatures during operation of the implanter. ΔX and ΔZ also may be used to adjust for ion beam conditions. This includes raising the ion beam current, which may require along the Z-Z axis toward the ion source, or changing ion beam energy. Lower ion beam energies generally have a smaller value along the Z-Z axis. Position of the assembly along the X-X axis interacts with the analyzer magnet and may determine the ion beam trajectory through the ion implanter. 
         [0049]    While an electrode assembly connected to manipulators is specifically disclosed herein, in an alternate embodiment the manipulators may be connected to individual electrodes within the ion implanter. This may increase the number of manipulators employed to adjust the electrode positions, but it can also enable finer positioning. As will be appreciated, use of the embodiments disclosed herein enables dynamic positioning of long or large electrodes. This positioning may reflect a large range of different ion beam energies or extracted ion beam currents. 
         [0050]    Referring now to  FIG. 15 , an exemplary method of adjusting an electrode assembly will be described. At step  1000 , first and second manipulators are provided at first and second ends of an electrode assembly. The first and second manipulators can be configured to adjust the positions of the first and second ends of the electrode assembly independently. At step  1100 , the first and/or second manipulators are actuated to adjust the first and/or second ends of the electrode assembly to thereby adjust a parameter of an ion beam received through an aperture in the electrode. At step  1200  a parameter of the ion beam may be measured. At step  1300 , a determination is made as to whether the measured parameter is outside a predetermined range. At step  1400 , the first and/or second actuators may be actuated to adjust the first and/or second ends of the electrode assembly to adjust the parameter of the ion beam to be within the predetermined range. 
         [0051]    In some embodiments, adjusting the first and second ends of the electrode comprises moving one of the first and second ends in at least one of two mutually perpendicular directions. In other embodiments, adjusting the first and second ends of the electrode comprises moving the first and second ends in at least one of two mutually perpendicular directions. In additional embodiments, a first of the two mutually perpendicular directions may be aligned with a travel direction of the ion beam. In further embodiments, moving at least one of the first and second ends in at least one of two mutually perpendicular directions comprises applying respective forces to first and second manipulator assemblies associated with the first and second ends. Applying respective forces can comprise adjusting a position of first and second actuation members coupled to the first and second manipulator assemblies. The respective forces may be applied via actuators positioned outside a vacuum chamber, and wherein the first and second manipulator assemblies are positioned within the vacuum chamber. 
         [0052]    The present disclosure is not to be limited in scope by the specific embodiments described herein. Indeed, other various embodiments of and modifications to the present disclosure, in addition to those described herein, will be apparent to those of ordinary skill in the art from the foregoing description and accompanying drawings. Thus, such other embodiments and modifications are intended to fall within the scope of the present disclosure. While the invention has been disclosed with reference to certain embodiments, numerous modifications, alterations and changes to the described embodiments are possible without departing from the spirit and scope of the invention, as defined in the appended claims. Accordingly, it is intended that the present invention not be limited to the described embodiments, but that it has the full scope defined by the language of the following claims, and equivalents thereof.