Abstract:
An electrode assembly for use in a plasma processing system that includes removable rails that are adjustable for reconfiguring the electrode to accommodate substrates of different widths. The electrode assembly includes an electrode having a plurality of first connecting members. Associated with the electrode is a plurality of rails that cooperate for supporting the substrates on the electrode. Each of the rails includes a plurality of second connecting members. Each of the second connecting members is connected detachably with one of the first connecting members for removably mounting the rails with the electrode.

Description:
FIELD OF THE INVENTION 
   The invention relates generally to plasma processing systems and, more particularly, to an electrode assembly for supporting substrates in a plasma processing system. 
   BACKGROUND OF THE INVENTION 
   Plasma processing systems are commonly used for modifying the surface properties of substrates in various industrial applications. For example, plasma processing systems are routinely used to plasma treat the surfaces of integrated circuits, electronic packages, and printed circuit boards in semiconductor applications, solar panels, hydrogen fuel cell components, automotive components, and rectangular glass substrates used in flat panel displays. Often, the substrates that are subjected to plasma processing have the geometrical form factor or shape of rectangular strips with opposite side edges that are substantially parallel. 
   Conventional plasma processing systems include a plasma chamber and a material handling system that transfers substrates to a processing space inside the plasma chamber for plasma treatment. Traditionally, electrodes inside the plasma chamber of an in-line plasma processing system have included rails used to support the transferred strips during plasma treatment. The rails are supplied in parallel pairs that are ideally aligned with corresponding rails on the material handling system. The rails inside the plasma processing system have a separation selected such that the rails contact side edges of each strip loaded from the material handling system onto the rails. 
   In one conventional electrode design, the substrate-supporting rails are formed integrally with the rest of the electrode. If the plasma processing system is retooled to plasma treat strips having a different width between the contacted side edges, the entire electrode must be replaced with a different electrode having integral rails with a different relative separation. This results in lost production time for replacing the electrode. Moreover, the integral rails on the new electrode may be misaligned with the rails on the material handling system, which is impossible to remedy with an adjustment to the electrode rails because of their integral construction. 
   To overcome this deficiency, plasma processing system manufacturers have introduced electrode assemblies with non-integral rails that are movable among multiple different separations across the surface of an electrode. This conventional rail construction features guide bars and rails with set screws that are loosened to change the separation between the rails constrained by the guide bars and tightened to fix the separation between the rails. Typically, an operator will make fiduciary marks on the electrode for use in aligning the rails to accept strips of different widths. However, aligning the rails with fiduciary marks to fix the rail positions is not readily reproducible, especially among multiple different operators, due in large part to the subjectivity involved in aligning the rails with the fiduciary marks. Moreover, the set screws must be loosened and tightened in order to change the distance between adjacent rails, which requires tools and slows the process. Productivity is lost during the time required to loosen each rail, align the rails with a set of fiduciary marks, and then tighten each rail without inadvertently altering the alignment. 
   It would be desirable, therefore, to provide an electrode construction for a plasma processing system that overcomes these and other deficiencies of conventional electrode constructions. 
   SUMMARY 
   In an embodiment of the present invention, an electrode assembly for supporting one or more substrates in a plasma processing system comprises an electrode having a plurality of first connecting members. Associated with the electrode is a plurality of rails that cooperate for supporting the substrates on the electrode. Each of the rails includes a plurality of second connecting members. Each of the second connecting members is connected detachably with one of the first connecting members for removably mounting the rails with the electrode. 
   In one specific embodiment of the present invention, an electrode assembly for supporting one or more substrates in a plasma processing system includes an electrode having first and second grooves that are aligned substantially parallel. A first bar is positioned in the first groove and a second bar is positioned in the second groove. The electrode assembly further includes a plurality of rails each removably engaged with the first and second bars and each extending between the first and second bars. The rails cooperate for supporting the substrates on the electrode. 
   The electrode assemblies of the invention may comprise a portion or component of a plasma processing system. The plasma processing system includes a vacuum chamber enclosing a processing space capable of being evacuated to a partial vacuum, a gas port defined in the vacuum chamber for admitting a process gas into the processing space, and a power supply. The electrode assembly is positioned in the processing space and is electrically coupled with the power supply for converting the process gas to the plasma. The electrode assemblies of the invention may also be retrofitted to existing plasma processing systems as a replacement for a conventional electrode. 
   The electrode assembly of the invention simplifies the process of configuring a plasma processing system to accept workpieces or substrates of a different size by readily adjusting the distance between adjacent substrate-supporting rails. The electrode assembly of the invention reduces or eliminates the potential for misalignment between a material handling system and the plasma processing system because of the high reproducibility in rail position when the electrode assembly is modified to change the spacing between adjacent rails. 
   These and other objects and advantages of the present invention shall become more apparent from the accompanying drawings and description thereof. 

   
     BRIEF DESCRIPTION OF THE FIGURES 
     The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the principles of the invention. 
       FIG. 1  is a perspective side view of a plasma processing system having an electrode assembly in accordance with an embodiment of the invention flanked by inlet-side and outlet-side material handling systems; 
       FIG. 1A  is a top view of the plasma processing system of  FIG. 1  shown from a perspective beneath the chamber lid and shown with unprocessed substrates supported by the inlet-side material handling system on the left, substrates to be processed supported by the plasma processing system, and processed substrates supported by the outlet-side material handling system; 
       FIG. 1B  is a diagrammatic view of the plasma processing system of  FIG. 1 ; 
       FIG. 2  is a perspective view of the electrode assembly of  FIG. 1 ; 
       FIG. 3  is an end view of one of the bars of  FIG. 2 ; 
       FIG. 3A  is a side view taken along line  3 A- 3 A in  FIG. 3 ; 
       FIG. 3B  is a bottom view taken along line  3 B- 3 B in  FIG. 3 ; 
       FIG. 3C  is a side view taken along line  3 C- 3 C in  FIG. 3 ; 
       FIG. 3D  is a top view taken along line  3 D- 3 D in  FIG. 3 ; 
       FIG. 4  is a top view of one of the central rails of  FIG. 2 ; 
       FIG. 4A  is an end view of the rail of  FIG. 4 ; 
       FIG. 4B  is a cross-sectional view taken generally along line  4 B- 4 B of  FIG. 4 ; 
       FIG. 4C  is an end view similar to  FIG. 4A  of one peripheral rail of  FIG. 2 ; 
       FIG. 4D  is an end view similar to  FIG. 4A  of the opposite peripheral rail of  FIG. 2 ; 
       FIG. 5  is a bottom view of the central rail of  FIG. 4 ; 
       FIG. 6  is a detailed view of an encircled region in  FIG. 2 ; 
       FIG. 7  is an end view in partial cross-section taken generally along line  7 - 7  in  FIG. 6  showing the coupling between a central rail and a bar of the electrode assembly; and 
       FIG. 8  is an end view in partial cross-section similar to  FIG. 7  in accordance with an alternative embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   With reference to  FIGS. 1 ,  1 A and  1 B, a plasma processing system  10  is flanked on an inlet side by a first material handling system  12  and on an outlet side by a second material handling system  14 . Material handling system  12  includes structure (not shown) that is capable of transferring a plurality of substrates  16  to the plasma processing system  10  for plasma treatment. Material handling system  12  includes structure (not shown) that is capable of removing the processed substrates  16  from the plasma processing system  10 . Each of the material handling systems  12 ,  14  may include structure, such as pinch wheels, pusher arms, and other mechanisms, for manipulating substrates  16  as understood by a person having ordinary skill in the art. 
   The plasma processing system  10  includes a chamber  20  consisting of a chamber base  22  and a chamber lid  24 . The chamber lid  24  is movable relative to the chamber base  22  between an opened position that permits access for substrate exchanges and a closed position. When the chamber lid  24  is in the closed position, an environment is created inside the chamber  20  suitable for plasma treatment of one or more substrates  16 . In its closed position, the chamber lid  24  is lowered such that a peripheral rim of the chamber lid  24  contacts a peripheral rim of the chamber base  22  in a sealing relationship that isolates a processing space  26  from the ambient atmosphere. When the chamber lid  24  is in the opened position, the chamber lid  24  is suspended from a pair of arms  23 ,  25  above the chamber base  22 . The arms  23 ,  25  are vertically movable for providing the opened and closed positions of the chamber lid  24  relative to the chamber base  22 . 
   The processing space  26  defined inside the atmospherically-sealed chamber  20 , which is created when the chamber lid  24  is closed, is evacuatable to a partial vacuum by a vacuum pump  28  coupled with a vacuum port  27  defined in chamber  20 . A gas supply  30  is coupled with a gas port  32  defined in chamber  20  and transfers a stream of an ionizable process gas to the processing space  26  inside the atmospherically-sealed chamber  20 . After an initial evacuation to remove atmospheric gases from the processing space  26 , the mass flow of process gas from the gas supply  30  to the processing space  26  and the pumping rate of spent and fresh process gases from the processing space  26  are regulated to provide a sub-atmospheric chamber pressure suitable for plasma treatment of substrates  16 . 
   A power supply  34 , such as a radiofrequency (RF) power supply, is electrically coupled with an electrode  36  associated with the chamber lid  24  and an electrode assembly  38  associated with the chamber base  22 . When the chamber  20  is sealed, evacuated, and supplied with process gas, the electrode  36  and electrode assembly  38  are energized by the power supply  34 . An electromagnetic field between the energized electrode  36  and electrode assembly  38  interacts with the process gas to generate a plasma inside the processing space  26 . If the power supply  34  supplies RF current to electrode  36  and electrode assembly  38 , the electromagnetic field interacting with the process gas inside the chamber  20  is time-varying. The substrates  16 , which are positioned in the processing space  26  between the electrode  36  and electrode assembly  38 , are exposed to the plasma to accomplish a plasma treatment. 
   The vacuum pump  28 , gas supply  30 , and power supply  34  have a construction understood by a person having ordinary skill in the art and will not be elaborated upon herein. The chamber  20  will also include various seals, gaskets, feedthroughs, etc. (not shown) required to provide an environment inside the chamber  20  suitable for plasma generation, as understood by a person having ordinary skill in the art. 
   With reference to  FIG. 2  in which like reference numerals refer to like features in  FIGS. 1 ,  1 A, and  1 B, the electrode assembly  38  associated with the chamber base  22  includes an electrode  40  having grooves  42 ,  44  that each receive one of a pair of bars  46 ,  48  to form an assembly. The grooves  42 ,  44  are generally parallel and are located near, and slightly inset from, opposite peripheral side edges of the electrode  40 . The depth of the grooves  42 ,  44  may be chosen such that an upper surface of each of the bars  46 ,  48  is substantially flush with an upper surface  41  of the electrode  40  when the bars  46 ,  48  are situated inside the grooves  42 ,  44 . The cross-sectional profile of the bars  46 ,  48  may be complementary to the cross-sectional profile of the grooves  42 ,  44 . Preferably, the bars  46 ,  48  may be interchangeably positioned among the grooves  42 ,  44 . 
   Associated with the bars  46 ,  48  is a plurality of, for example, five guide and support rails  50 ,  52 ,  54 ,  56 ,  58  of which rails  50 ,  58  are peripheral rails and rails  52 ,  54 ,  56  are central rails positioned on the surface of the electrode  40  between rail  50  and rail  58 . The rails  50 ,  52 ,  54 ,  56 ,  58  are aligned substantially orthogonal or perpendicular to the bars  46 ,  48 . The rails  50 ,  52 ,  54 ,  56 ,  58 , which have a mutually parallel arrangement, are substantially collinear with a corresponding plurality of rails  60  associated with material handling system  12  to define a plurality of lanes along which unprocessed substrates  16  are loaded into the chamber  20 . Similarly, the rails  50 ,  52 ,  54 ,  56 ,  58  are substantially collinear with a corresponding plurality of rails  62  associated with material handling system  14  to define a plurality of lanes along which processed substrates  16  are unloaded into the chamber  20 . Each of the lanes is defined between an adjacent pair of rails  60 , between an adjacent pair of rails  62 , and between adjacent pairs of rails  50 ,  52 ,  54 ,  56 ,  58  so that the material handling systems  12 ,  14  and the plasma processing system  10  have an equivalent number of lanes. A person having ordinary skill in the art will appreciate that the specific number of rails may vary contingent upon, among other factors, the dimensions of the substrate  16  and the dimensions of the chamber  20 . 
   Rails  50 ,  52 ,  54 ,  56 ,  58  cooperate for supporting the substrates  16  in a distanced relationship with the upper surface  41  of the electrode  40 . Specifically, the rails  50 ,  52 ,  54 ,  56 ,  58  elevate the substrates  16  above the upper surface  41  of electrode  40  during plasma treatment that exposes the substrates  16  to the plasma in the processing space  26 . 
   With reference to FIGS.  3  and  3 A-D in which like reference numerals refer to like features in  FIGS. 1 ,  1 A,  1 B, and  2 , bar  48  may be centered about a longitudinal axis  63 . Bar  48 , which may be tubular, includes a plurality of sides  64 ,  66 ,  68 ,  70  of substantially equal area that face outwardly and define the exterior surface of the bar  48 . Sides  64  and  66  intersect along right-angle corner  72 , sides  66  and  68  intersect along right-angle corner  74 , sides  68  and  70  intersect along right-angle corner  76 , and sides  70  and  64  intersect along right-angle corner  78 . As such, bar  48  has a four-sided polygonal cross-sectional profile. 
   As best shown in  FIG. 3A , arranged along the length of side  64  is a plurality of openings  80  in which the adjacent pairs of openings  80  are separated by a spacing S 1 . The openings  80  are aligned linearly and are centrally positioned between right-angle corners  72 ,  78  that border the longitudinal edges of side  64 . Side  64  includes an identifier  82  that may be inscribed into the material forming bar  48 . The identifier  82  provides a ready indication to an operator of the value of the opening spacing S 1  so that the operator can reliably determine the distance between adjacent openings  80 . 
   As best shown in  FIG. 3B , a plurality of openings  84  is also arranged along the length of side  66  in which the adjacent pairs of openings  84  are separated by a spacing S 2 . The openings  84  are aligned linearly and are centrally positioned between right-angle corners  72 ,  74  that border the longitudinal edges of side  66 . Side  66  includes an identifier  86  that may be inscribed into the material forming bar  48 . The identifier  86  provides an indication to an operator of the value of the opening spacing S 2  so that the operator can readily and reliably determine the distance between adjacent openings  84 . 
   Similarly and as best shown in  FIG. 3C , a plurality of openings  88  is arranged along the length of side  68 . The adjacent pairs of openings  88  are separated by a spacing S 3 . The openings  88  are aligned linearly and are centrally positioned between right-angle corners  74 ,  76  that border the longitudinal edges of side  68 . Side  68  includes an identifier  90  that may be inscribed into the material forming bar  48 . The identifier  90  provides an indication to an operator of the value of the opening spacing S 3  so that the operator can readily and reliably determine the distance between adjacent openings  88 . 
   As best shown in  FIG. 3D , a plurality of openings  92  is also arranged along the length of side  70 . The adjacent pairs of openings  92  are separated by a spacing S 4 . The openings  92  are aligned linearly and are centrally positioned between right-angle corners  76 ,  78  that border the longitudinal edges of side  70 . Side  70  includes an identifier  94  that may be inscribed into the material forming bar  48 . The identifier  94  provides an indication to an operator of the value of the opening spacing S 4  so that the operator can readily and reliably determine the distance between adjacent openings  92 . 
   The identifiers  82 ,  86 ,  90 ,  94  may be formed in the bar  48  by other vacuum-compatible methods as understood by persons having ordinary skill in the art. When the bar  48  is installed in groove  42 , only one of the sets of openings  80 ,  84 ,  86 ,  88  is exposed as the remaining three sets of openings  80 ,  84 ,  86 ,  88  are hidden by portions of the electrode  40  bounding the groove  42 . The exposed one of the sides  64 ,  66 ,  68 ,  70  and, hence, the exposed set of openings  80 ,  84 ,  86 ,  88 , is changed by lifting the bar  48  and rotating the bar  48  about longitudinal axis  63 . 
   The identifiers  82 ,  86 ,  90 ,  94  permit rapid identification of the particular opening spacing on each of the sides  64 ,  66 ,  68 ,  70 . Each of the identifiers  82 ,  86 ,  90 ,  94  may comprise at least one alphanumeric character indicative or suggestive of the corresponding distance or spacing between adjacent pairs of openings  80 ,  84 ,  88 ,  92 , respectively. Alternatively, the identifiers  82 ,  86 ,  90 ,  94  may comprise simple non-alphanumeric geometrical shapes, such as bars or circles, indicative or suggestive of the corresponding distance or spacing between adjacent pairs of openings  80 ,  84 ,  88 ,  92 , respectively. The invention may, in an alternative embodiment, mark fewer than all of the sides  64 ,  66 ,  68 ,  70  by omitting one or more of the corresponding identifiers  82 ,  86 ,  90 ,  94 . 
   Bar  46  has a construction substantially identical to the construction of bar  48  so that each of the bars  46 ,  48  may be installed in either of the grooves  42 ,  44  in electrode  40 . When bar  48  is installed in groove  44 , one of the sides  64 ,  66 ,  68 ,  70  is exposed and visible. Similarly, when bar  46  is installed in groove  42 , a side of bar  46  corresponding to the exposed one of sides  64 ,  66 ,  68 ,  70  of bar  48  is exposed and visible. The bars  46 ,  48  are positioned in their respective grooves  42 ,  44  such that the openings in bar  48 , for example openings  80  on side  64 , directly opposite to the openings  80  in side  64  of bar  46 . This correlation ensures that the installed rails  50 ,  52 ,  54 ,  56 ,  58  have a substantially parallel relationship with a uniform spacing between adjacent pairs of rails  50 ,  52 ,  54 ,  56 ,  58 . The spacing between adjacent pairs of rails  50 ,  52 ,  54 ,  56 ,  58  is readily determined by reference to the corresponding one of the identifiers  82 ,  86 ,  90 ,  94  on bars  46 ,  48  and is specified by the accessible set of openings  80 ,  84 ,  88 ,  92 . 
   In alternative embodiments of the present invention, the bars  46 ,  48  may have different configurations. For example, the grooves  42 ,  44  and bars  46 ,  48  may have a different complementary cross-sectional profiles, such as a complementary polygonal cross-sectional profiles with less than or more than four contiguous sides. 
   In other alternative embodiments of the present invention, fewer than all of the sides  64 ,  66 ,  68 ,  70  of bars  46 ,  48  may include the respective set of openings  80 ,  84 ,  88 ,  92 . For example, only two sides, such as sides  64  and  66 , of each of the bars  46 ,  48  may be populated with openings  80 ,  82 , respectively, as shown in  FIG. 3 , and the remaining sides  68 ,  70  may omit openings. In this instance, another set of bars (not shown) may be provided that have sides populated with openings having the same spacings as openings  80 ,  82  of bars  46 ,  48  so that this new set of bars and bars  46 ,  48  with populated sides  64 ,  66  will provide the same set of possible rail spacings as bars  46 ,  48  with populated sides  64 ,  66 ,  68 ,  70 . 
   In yet other alternative embodiments of the present invention, a set of four bars (not shown) may each include only a single side that is populated with openings and be useable as a substitute for at least one of the bars  46 ,  48 . In this instance, the four bars would have one side similar in appearance to  FIGS. 3A-D . 
   With reference to  FIGS. 4 ,  4 A,  4 B, and  5  in which like reference numerals refer to like features in  FIGS. 1-3 , rail  56 , which is representative of rail  52  and rail  54 , includes a pair of support surfaces or shelves  96 ,  98  separated by a central divider  100 . The support shelves  96 ,  98  extend between opposite ends  105 ,  107  of the rail  56 . The support shelves  96 ,  98  are spaced from a bottom surface  102  that is adjacent to the electrode  40  when the rail  56  is mounted to bars  46 ,  48 . The support shelves  96 ,  98  each include a beveled surface  104 ,  106 , respectively, at the end  105  of rail  56  that faces toward material handling system  12  when the rail  56  is coupled with bars  46 ,  48 . The beveled surfaces  104 ,  106  are used to guide substrates  16  transferred from rails  60  of material handling system  12  vertically to provide a tolerance for vertical misalignment of rails  60  with rail  56  and the other rails  52 ,  54  that also include the beveled ends  104 ,  106 . 
   The central divider  100  has opposite sidewalls  116 ,  118  that extend vertically to intersect with a corresponding one of the support shelves  96 ,  98 . The separation, W 1 , between the sidewalls  116 ,  118  at end  105  is narrower than the separation, W 2 , between the sidewalls  116 ,  118  at any point along the length of the rail  56 . As a result, the support shelves  96 ,  98  are wider near end  105 , which is adjacent to the rails  60  of material handling system  12 , than near end  107 , which is adjacent to the rails  62  of material handling system  14 . Each of the support shelves  96 ,  98  attains a minimum width at a location L from end  105  and has a constant width from that location to end  107 . The increased width of the support shelves  96 ,  98  near end  105  operates to correct lateral misalignment of the substrates  16  during loading. In one specific embodiment of the invention, divider  100  has a width W 1  at end  105  equal to about 4.5 mm and a maximum width W 2  near end  107  equal to about 6.5 mm, and the location L is about 260 mm from end  105 . 
   Projecting from the bottom surface  102  of rail  56  is a pair of pins or posts  108 ,  110  that are used to engage the rail  56  with the bars  46 ,  48 . Post  108  is spaced along the length of rail  56  from post  110  by a distance, P, substantially equal to the mid-line distance, G, between grooves  42 ,  44  in electrode  40 , as shown in  FIG. 2 . The coupling of posts  108 ,  110  with the openings  80  on side  64 , as well as openings  84 ,  88 ,  92  on sides  66 ,  68 ,  70 , respectively, is highly reproducible. The posts  108 ,  110  have a fixed separation and the openings  80 ,  84 ,  88 ,  92  have a fixed separation, which eliminates user subjectivity when adjusting the position of rail  56 , and rails  50 ,  52 ,  54 ,  58 . 
   With reference to  FIG. 4C  in which like reference numerals refer to like features in  FIG. 4B , rail  58  is a peripheral rail and has a single support shelf  112  that is constructed identical to support shelf  96  on rail  56  ( FIG. 4B ). The support shelf  112  has a beveled surface  120  similar or identical to beveled surfaces  104 ,  106  ( FIG. 4A ) on rail  56 , a divider  120  similar or identical to divider  100  ( FIG. 4A ) on rail  56 , and a sidewall  122  similar or identical to sidewall  116  ( FIG. 4A ). With reference to  FIG. 4D , rail  50 , which is also a peripheral rail, has a single support shelf  114  that is constructed identical to support shelf  98  on rail  56  ( FIG. 4B ). The support shelf  114  has a beveled surface  124  similar or identical to beveled surfaces  104 ,  106  ( FIG. 4A ) on rail  56 , a divider  126  similar or identical to divider  100  ( FIG. 4A ) on rail  56 , and a sidewall  128  similar or identical to sidewall  116  ( FIG. 4A ). 
   With reference to  FIGS. 6 and 7  in which like reference numerals refer to like features in  FIGS. 1-5 , rail  56  has one end coupled by pin  108  with one of the openings  80  in side  64  of bar  46  and an opposite end coupled by pin  110  with one of the openings  80  in side  64  of bar  48 . Pins  108 ,  110  project through the openings  80  and partially into the interior of the bars  46 ,  48 , respectively. Rails  50 ,  52 ,  54 ,  58  have an engagement with bars  46 ,  48  that is substantially identical to the engagement between rail  56  and bars  46 ,  48 . Of course, another of the sides  66 ,  68 ,  70  of each of the bars  46 ,  48  may be exposed to change the width of the substrate  16  being plasma processed by the plasma processing system  10 . The rails  50 ,  52 ,  54 ,  58 , when engaged with the bars  46 ,  48 , extend between the bars  46 ,  48 . 
   The bars  46 ,  48 , grooves  42 ,  44 , and openings  80 ,  84 ,  88 ,  92  operate as one set of connecting members and the pins  108 ,  110  of each of the rails  50 ,  52 ,  54 ,  58  operate as a second complementary set of connecting members that detachably engage one set of openings  80 ,  84 ,  88 ,  92  for detachably connecting the rails  50 ,  52 ,  54 ,  58  with the electrode  40  to form electrode assembly  38 . These complementary connecting member constructions may be varied for detachably connecting the rails  50 ,  52 ,  54 ,  58  with the electrode  40 . For example, the pins  108 ,  110  and openings  80 ,  84 ,  88 ,  92  may have different complementary geometrical shapes. Alternatively, the pins  108 ,  110  and openings  80 ,  84 ,  88 ,  92  may be replaced with a different construction that provides the same certainty and reproducibility in detachably connecting the rails  50 ,  52 ,  54 ,  58 . As another example, the grooves  42 ,  44  and bars  46 ,  48  may be shaped and dimensioned such that a portion of each of the bars  46 ,  48  project above the electrode  40  and the rails  50 ,  52 ,  54 ,  58  may be formed with recesses (not shown) near each opposite end that receive the projecting portion of the respective bars  46 ,  48 . 
   With reference to  FIG. 8  in which like reference numerals refer to like features in  FIGS. 1-7 , an optional height-adjustment member in the form of spacer  120  may be inserted between the rail  56  and the bar  48  and another optional height-adjustment member or spacer (not shown) similar or identical to spacer  120  may be inserted between the rail  56  and the bar  46  for changing the height of the support shelves  96 ,  98  above the upper surface of electrode  40 . This adjustment permits the vertical position of rail  56  to be adjusted relative to the electrode  40  to match the vertical position of the rails  60  of material handling system  12 . Spacer  120  may be a washer-like annular structure that is installed about the pin  108  or have another construction. Similar spacers (not shown) may be provided for adjusting the vertical height of the other rails  50 ,  52 ,  54 ,  58 . 
   To configure the electrode assembly  38  of plasma processing system  10  for handling substrates  16  of differing width and with reference to  FIGS. 1-8 , the chamber lid  24  is moved relative to the chamber base  22  to the opened position to permit access to the electrode assembly  38 . The rails  50 ,  52 ,  54 ,  56 ,  58  are removed by a vertical lifting motion that releases the pins  108 ,  110  from their confinement. The bars  46 ,  48  are each re-oriented within grooves  42 ,  44  of electrode  40  such that the same corresponding one of the sides  64 ,  66 ,  68 ,  70  is exposed along the top surface of electrode  40 . Alternatively, another set of bars (not shown) with different opening spacings may be installed in grooves  42 ,  44 . The rails  50 ,  52 ,  54 ,  56 ,  58  are re-installed by coupling with grooves  42 ,  44 , unless the number of rails is changed to accommodate material handling systems  12 ,  14  with a different number of lanes. The optional spacers  120  may be installed for increasing the distance separating the support shelves  92 ,  94  on rails  52 ,  54 ,  58 , support shelf  112  on rail  58 , and support shelf  114  on rail  50  from electrode  40 . 
   During use, a side edge of at least one substrate  16  may contact each of the support shelves  92 ,  94  on rails  52 ,  54 ,  58 , support shelf  112  on rail  58 , and support shelf  114  on rail  50 . For example and as shown in  FIG. 6 , one of the substrates  16  has a side edge supported on support shelf  98  of rail  56  and another side edge supported on support shelf  112  of rail  58 . 
   The electrode  40 , rails  50 ,  52 ,  54 ,  56 ,  58 , and bars  46 ,  48  may be formed from a conductive material, such as aluminum or an aluminum alloy. The pins  108 ,  110  may be formed from a stainless steel for durability in repeatedly coupling and uncoupling rails  50 ,  52 ,  54 ,  56 ,  58  from bars  46 ,  48 . When assembled, the electrode  40 , rails  50 ,  52 ,  54 ,  56 ,  58 , and bars  46 ,  48  comprise a conductive electrode assembly. 
   A second set of bars (not shown) may be supplied for use with electrode assembly  38  that have opening spacings that differ from the specific opening spacings of bars  46 ,  48 . The opening spacings may be selected to meet a particular customer&#39;s requirements for strip width. Rails  50 ,  52 ,  54 ,  56 ,  58  are designed to be used with any arbitrary set of bars  46 ,  48 . Hence, only a single set of rails  50 ,  52 ,  54 ,  56 ,  58  is required. However, the specific number of rails may vary depending upon the number of substrate lanes to be provided on electrode assembly  38 . For example, rails  50 ,  52 ,  54  and  58  may be used if the electrode assembly  38  only includes three lanes for receiving substrates  16 , instead of four lanes. As another example, rails  50  and  58  may be used if electrode assembly  38  includes only a single lane for receiving substrates  16 . 
   While the present invention has been illustrated by a description of various embodiments and while these embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant&#39;s general inventive concept. The scope of the invention itself should only be defined by the appended claims, wherein I claim: