Abstract:
An apparatus for processing wafer-shaped articles comprises a closed process chamber, a chuck located within the closed process chamber, and at least one process liquid dispensing device disposed within the chamber. The closed process chamber comprises a lid that can be opened to position a wafer-shaped article within the closed process chamber. The lid incorporates a heater adapted to heat a wafer-shaped article positioned in the closed process chamber.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates generally to an apparatus for treating a wafer-shaped article, such as a semiconductor wafer. 
         [0003]    2. Description of Related Art 
         [0004]    Semiconductor wafers are subjected to various surface treatment processes such as etching, cleaning, polishing and material deposition. To accommodate such processes, a single wafer may be supported in relation to one or more treatment fluid nozzles by a chuck associated with a rotatable carrier, as is described for example in U.S. Pat. Nos. 4,903,717 and 5,513,668. 
         [0005]    Such spin chucks may be accommodated in closed process chambers, as described for example in commonly-owned co-pending U.S. patent application Ser. No. 12/913,405, filed Oct. 27, 2010. Certain cleaning processes utilize aggressive liquid chemicals at elevated temperatures, as described for example in commonly-owned co-pending U.S. patent application Ser. No. 12/959,924, filed Dec. 3, 2010. 
         [0006]    However, when a high temperature process is performed in an environmentally controlled process chamber, it can be difficult to maintain the desired temperature of the process liquid across the surface of the wafer, especially for wafers of relatively larger diameter, such as 300 mm and above. 
       SUMMARY OF THE INVENTION 
       [0007]    An apparatus for processing wafer-shaped articles according to the present invention comprises a closed process chamber, a chuck located within the closed process chamber, and at least one process liquid dispensing device disposed within the chamber. The closed process chamber comprises a lid that can be opened to position a wafer-shaped article within the closed process chamber. The lid comprises a heater adapted to heat a wafer-shaped article positioned in the closed process chamber. 
         [0008]    In preferred embodiments of the apparatus according to the present invention, the heater comprises a plurality of infrared heating elements. 
         [0009]    In preferred embodiments of the apparatus according to the present invention, the infrared heating elements are individually tuneable to apply a desired heating profile to a surface of a wafer-shaped article positioned within the closed process chamber. 
         [0010]    In preferred embodiments of the apparatus according to the present invention, the lid is axially displaceable relative to a remaining structure of the closed process chamber while sealingly engaged with the remaining structure, so as to vary a distance between the heater and a wafer-shaped article positioned within the closed process chamber. 
         [0011]    In preferred embodiments of the apparatus according to the present invention, the heater comprises one or a plurality of infrared heating elements, and the lid comprises a downwardly-facing peripheral shield that is essentially opaque to IR radiation. 
         [0012]    In preferred embodiments of the apparatus according to the present invention, the lid comprises an internal gas inlet communicating with one or more internal peripheral recesses surrounding the heater, to permit a cooling gas to be supplied adjacent a periphery of the heater. 
         [0013]    In preferred embodiments of the apparatus according to the present invention, the internal gas inlet is disposed in a central region of the lid, and is connected to the one or more internal peripheral recesses by a plurality of radially extending channels. 
         [0014]    In preferred embodiments of the apparatus according to the present invention, the heater comprises one or a plurality of infrared heating elements, and the lid comprises an internal IR shield separating the one or a plurality of infrared heating elements from the one or more internal peripheral recesses. 
         [0015]    In preferred embodiments of the apparatus according to the present invention, the heater is sealed within the lid so as to be protected from contact with process liquids inside the closed process chamber. 
         [0016]    In preferred embodiments of the apparatus according to the present invention, the lid comprises at least one gas nozzle opening on or extending beyond a downwardly facing surface of the lid, so as to supply gas into the closed process chamber. 
         [0017]    In preferred embodiments of the apparatus according to the present invention, the apparatus includes a drive unit for the at least one process liquid dispensing device, the drive unit being drivingly connected to the at least one dispensing device to move the at least one dispensing device from a peripheral standby position to one or more active positions in which a dispensing end of the at least one dispensing device is moved radially inwardly of the chuck, the drive unit being mounted outside of the chamber. 
         [0018]    In preferred embodiments of the apparatus according to the present invention, the chamber is a component of a process module for single wafer wet processing of semiconductor wafers. 
         [0019]    In preferred embodiments of the apparatus according to the present invention, the chuck is a spin chuck having a drive shaft extending downwardly from the chamber. 
         [0020]    In preferred embodiments of the apparatus according to the present invention, the at least one process liquid dispensing device is operable to dispense liquid into the chamber while the lid is in the closed position. 
         [0021]    In preferred embodiments of the apparatus according to the present invention, the chuck is vertically movable relative to the closed process chamber, and is configured to have at least three stopping positions, these being an uppermost position for loading and unloading a wafer-shaped article from the chuck, and at least two lower positions within the chamber, each of the at least two lower positions corresponding to a distinct process level of the chamber. 
         [0022]    In preferred embodiments of the apparatus according to the present invention, the apparatus includes a drive mechanism that moves the lid from the closed position to the open position, the drive mechanism being adapted to displace the lid both upwardly and laterally relative to the chamber. 
         [0023]    In preferred embodiments of the apparatus according to the present invention, drive unit is a motor mounted on a side housing of the chamber, an output shaft of the motor passing into the side housing and driving a link that passes into the chamber and connects to the at least one liquid dispensing device. 
         [0024]    In preferred embodiments of the apparatus according to the present invention, the at least one process liquid dispensing device is a media supply arm pivotably mounted within the chamber and movable from a peripheral standby position to one or more active positions in which a dispensing end of the media supply arm is moved radially inwardly of the chuck. 
         [0025]    In preferred embodiments of the apparatus according to the present invention, the media supply arm has one end pivotally connected to a link that passes through a wall of the chamber and an opposite end provided with a dispensing nozzle. 
         [0026]    In preferred embodiments of the apparatus according to the present invention, the lid is arranged parallel to a wafer-shaped article received on the chuck. 
         [0027]    In preferred embodiments of the apparatus according to the present invention, the closed process chamber comprises a plurality of superposed process levels, each of the plurality of superposed process levels having a respective gas exhaust connected thereto, wherein the gas exhausts are individually controllable. 
         [0028]    In preferred embodiments of the apparatus according to the present invention, the closed process chamber is mounted on an upper surface of a base plate, and the apparatus also includes a drive unit for the chuck mounted in a housing that depends from a lower surface of the base plate. 
         [0029]    In preferred embodiments of the apparatus according to the present invention, the drive mechanism that moves the lid from the closed position to the open position is mounted on a lower surface of a base plate, and the closed process chamber is mounted on an upper surface of the base plate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    Other objects, features and advantages of the invention will become more apparent after reading the following detailed description of preferred embodiments of the invention, given with reference to the accompanying drawings, in which: 
           [0031]      FIG. 1  is a perspective view of a preferred embodiment of a closed chamber module according to the present invention; 
           [0032]      FIG. 2  is a view similar to  FIG. 1 , in which the chamber lid has been moved up and away from the module, so as to permit loading or unloading of the module; 
           [0033]      FIG. 3  is a perspective view of the  FIG. 1  embodiment from below, showing several of the mechanisms used to operate the module; 
           [0034]      FIG. 4  is another perspective view of the  FIG. 1  embodiment, sectioned in an axial plane, so as to illustrate internal components thereof; 
           [0035]      FIG. 5  is an axial cross-section of the  FIG. 1  embodiment, in the same plane as that of  FIG. 4 ; 
           [0036]      FIG. 6  is a perspective view from above of the lid of the  FIG. 1  embodiment; 
           [0037]      FIG. 7  is a top plan view of the lid, in which the cover is rendered in transparent form; 
           [0038]      FIG. 8  is a perspective view from below of the lid of the  FIG. 1  embodiment; 
           [0039]      FIG. 9  is a cross-sectional view along the line A-A of  FIG. 7 ; 
           [0040]      FIG. 10  is a cross-sectional view along the line D-D of 
           [0041]      FIG. 7 ; 
           [0042]      FIG. 11  is an axial cross-section of the  FIG. 1  embodiment in a plane that intersects the pivotal mounting of one of the media supply arms; 
           [0043]      FIG. 12  is a sectional view illustrating the mechanism for driving and raising and lowering the spin chuck of this embodiment; 
           [0044]      FIG. 13  is a radial section of the  FIG. 1  embodiment, illustrating the media supply arms in their standby position; 
           [0045]      FIG. 14  is a fragmentary perspective view of the pivotal mounting of one of the media supply arms; 
           [0046]      FIG. 15  is a radial section of the  FIG. 1  embodiment, in which one of the media supply arms has been pivoted to its service position; and 
           [0047]      FIG. 16  is a perspective view of the  FIG. 1  embodiment, with the upper chamber cover removed. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0048]    Referring to  FIG. 1 , a closed chamber module  10  is mounted on a base plate  15 , and is constituted by a preferably cylindrical chamber wall  30  and an annular upper chamber cover  32  secured to the chamber wall  30  by a series of screws or the like. The chamber module  10  is closed at its upper end by a lid  100 , which seals at its outer periphery to the inner periphery of the annular upper chamber cover  32 . 
         [0049]    Lid  100  is secured to lid arm  22 , which moves the lid  100  from the closed position shown in  FIG. 1  to the open position shown in  FIG. 2 , and which is in turn positioned on lid support shaft  26 . A gas feed line  24  supplies gas to the lid  100 . In practice a plurality of gas feed lines may be provided. 
         [0050]    First and second drive units  52 ,  62  are provided for respective media supply arms to be described below, and lead to respective covers  54 ,  64  for the pivotal movement mechanisms for the media supply arms. Reference numeral  56  denotes a lead-in for the first media supply line. 
         [0051]    The closed chamber module of this embodiment has three interior levels, each of which has an associated gas exhaust, with reference numerals  82 ,  84  and  86  in  FIG. 1  denoting the associated exhausts for the lower, middle and upper levels, respectively and  81 ,  83  and  85  denoting the associated lower, middle and upper gas suctions for those exhausts. 
         [0052]    Referring now to  FIG. 2 , the closed chamber module is shown in its open position, which involves both raising the lid upwardly relative to the chamber and pivoting it about the lid support shaft  26 , which accommodates the hollow shaft  18 . 
         [0053]    Inside the chamber, spin chuck  70  is visible, which in this embodiment is a chuck of the double-sided type. Also visible are the second media supply arm  63  in its standby position, and upper, middle and lower levels  34 ,  35 ,  36 . 
         [0054]    In  FIG. 3 , the underside of the lid  100  includes a central gas nozzle  23 . 
         [0055]    Motor  27 , which may for example be a pneumatic cylinder, drives link  19 , which in turn drives hollow shaft  18  (see  FIG. 4 ). Motor  27  thus drives the pivotal movement of lid  100 . Motor  28  is a lifting motor for raising and lowering the lid  100 , whereas  29  denotes a lead-in for the gas feed lines  21 ,  24  that are accommodated in the hollow shaft  18 . 
         [0056]    A spin motor  72  spins the spin chuck  70 , whereas motor  76  raises and lowers spin chuck  70  via slider  74 . A lower chamber cover  31  accommodates the bellows of the spin chuck, as will be described below. 
         [0057]    In  FIG. 4 , the upper, middle and lower levels  34 ,  35  and  36  are more readily visible. The structure of these levels and their respective exhausts  86 ,  84  and  82  may be as described in commonly-owned application WO 2004/084278 A1. Also visible in  FIG. 4  is the gas feed line  21  for the central gas nozzle  23 , an expansion bellows  75  that serves to isolate the drive mechanisms from the interior ambient of the chamber, a frame  77  that connects the chuck drive mechanism to the underside of the chamber, a non-rotating nozzle head  79  supplying the bottom nozzles of the chuck, and a non-rotating hollow shaft  78  accommodating the bottom nozzle head  79 . 
         [0058]    The axial cross-section of  FIG. 5  shows the afore-mentioned components in greater detail, along with the plate  37  defining the chamber bottom, the first media supply arm  53  shown in its standby position, and the stowage area  55  for the arm  53 . It will be noted that shaft  18  is rigidly secured to lid arm  22 , such that the rotational and translational movements imparted to shaft  18  are imparted to lid arm  22  and lid  100  as well, as described below. 
         [0059]    Lid  100  is depicted in greater detail in  FIGS. 6-10 . A plurality of electrical connectors  122  are provided for the heating lamps  120 . The upper cover of lid  100  is normally optically opaque but is rendered in transparent form in  FIG. 7 , to reveal the infrared lamps  120  and the ribs  115 , between which the channels of the cooling gas distribution network are established. 
         [0060]    As shown in  FIGS. 7-9 , lid  100  includes twelve linear infra red (IR) heaters  120 . The IR-heaters are separately tunable, so as to achieve a desired uniformity of heating across the wafer surface. For example, if it is found out that the wafer edge is not heated fast enough the power to the outermost IR-heaters  120  is increased. The tuning of the IR-heaters can be optimized by monitoring the treated wafers regarding the uniformity of heating or by monitoring the temperature increase using local thermometers. 
         [0061]    The IR-heaters are preferably linear quartz rods. There is an isolative coating provided so that the IR-heaters primarily emit IR-light towards the wafer surface. 
         [0062]    The chamber and the IR-heaters are separated by a transparent plate  135 , e.g. made of heat resistant glass (borosilicate glass), or quartz. Surrounding transparent plate  135  is an annular peripheral shield  125 , which is formed of stainless steel or another material that is essentially opaque to infrared radiation. Shield  125  thus serves to focus the IR radiation onto the wafer surface and prevents the surrounding parts (e.g. the chamber walls), which are often made from a plastic material, from being excessively heated. 
         [0063]    The assembly of IR heaters  120  is sealed within the lid  100  so that process liquid inside the sealed chamber cannot make contact with the IR heaters  120 . This can be important for example when the process liquid is flammable, for example in the case of hot isopropyl alcohol used during drying treatments. 
         [0064]    Although the heating elements in this embodiment are linear tubes, the heating elements may alternatively be embodied as tunable spot type IR lamps or concentric annular heating elements. 
         [0065]    As shown in  FIG. 10 , the lid  100  in this embodiment comprises an outer plate  130  and also an inner plate  136 . Inner plate  136  is preferably also an IR shield. Between the outer plate and the inner plate there is a gas distribution chamber  133  that is purged with cooling gas (preferably an inert gas such as nitrogen). The cooling gas is introduced through feed pipe  129  and distributed to six radially arranged gas distribution chambers  133  through channels  131  that are defined by ribs  115 . The ribs  115  are part of the outer plate  130  and are arranged like spokes radiating from the center of lid  100 . As  FIG. 9  is a cross-section through one of the ribs  115 , the gas distribution network is better seen in  FIG. 10 . 
         [0066]    Lid  100  in this embodiment is also axially displaceable relative to lid arm  22 , by virtue of its mounting thereto via a series of six rods  103  that are rigidly secured to lid  100  but whose enlarged heads  104  are captive within pockets formed in lid arm  22 , and in which they may slide axially upwardly against the force of springs  105  that surround the rods  103  and that bear via their upper ends on lid arm  22  and via their lower arms on the outer cover  133  of lid  100 . A suitable gear motor or the like (not shown) can thus vary the spacing between the lid  100  and lid arm  22 , and thus the spacing between the set of IR heating elements  120  and the upper surface of a wafer positioned with the process chamber. This axial positioning thus permits further tuning of the heating profile to be applied to a wafer. 
         [0067]    In the axial cross-section of  FIG. 11 , the sectioning plane passes through the cover  54  of the pivot mechanism for the first media supply arm  53 . From this angle, the second media supply arm  63  is fully visible in its standby position. Reference numeral  17  denotes a pressure-equalizing chamber with the lid  100 . An annular seal  33  such as an O-ring or V-seal is attached to or seated in the annular upper chamber cover  32 , to form a seal with the lid  100 . However, when the lid  100  is axially displaceable relative to the lid arm  22 , then the cylindrical side surface of lid  100  is adapted to remain sealingly engaged with upper chamber  32  throughout the range of axial travel of lid  100  relative to lid arm  22 . 
         [0068]    Turning now to  FIG. 12 , the mechanism for rotating the spin chuck carrier  73  comprises a rotating hollow shaft  71  that drives the spin chuck carrier  73  in rotation, the expansion bellows  75  that shields the drive mechanisms from the interior ambient of the chamber, frame  77  connecting the chuck drive mechanism to the underside of the chamber, non-rotating nozzle head  79  supplying the bottom nozzles of the chuck, and non-rotating hollow shaft  78  accommodating the bottom nozzle head  79 . 
         [0069]    Non-rotating hollow shaft  90  surrounds rotating hollow shaft  71 , which in turn surrounds non-rotating hollow shaft  78 , these three shafts being coaxial with one another. Rotary shaft seal bearing  91  seals the coaxial shafts from the chamber ambient and supports the interconnected rotary hollow shaft  78  and chuck carrier  73 , whereas bearing  92  connects the non-rotating upper ring  94  with the rotating shaft  71 . Membrane cover  93  is fitted within lower chamber cover  31 , and at its inner periphery seals against bellows  75 , and at its outer periphery seals against the chamber bottom  37 . 
         [0070]    In  FIG. 13 , the radial section through the cylindrical chamber wall  30  reveals first and second media supply arms  53  and  63  in their standby position, with the broken lines in  FIG. 8  tracing the arcuate path that the dispensing ends of the media arms  53 ,  63  travel as they are moved from the illustrated standby position to the service position in which the dispensing end of the media arm will be approximately centered over the spin chuck. In practice only one of the media arms will be in use and hence in its service position at any given time, that is, although the media supply arms  53 ,  63  will often both be in the standby position as illustrated, in use typically only one or the other will be in the service position. Nevertheless, both media supply arms  53 ,  63  can move simultaneously, however alternatively approaching the centre, which can be achieved by appropriate software commands. 
         [0071]    In referring to a service position for the media supply arms  53 ,  63 , it will be understood that there can be more than one service position, or for that matter the arms may be in service as they move radially inwardly from the peripheral standby position. Therefore, the service position can refer to any position where the dispensing end of the media supply arm is positioned above a wafer supported on the chuck, and not merely the central innermost position. For instance the service position will move from centre towards the edge and back again during processing of the wafer. 
         [0072]      FIG. 14  shows further detail of the mechanism for driving the media supply and dispense arms between their standby and service positions. Cover  64  is indicated only in broken line in  FIG. 14 , to permit viewing the interior components of the drive mechanism. In practice cover  64  will be made of a solid material mounted in a sealed manner to the cylindrical wall  30  of the chamber, the cylindrical wall  30  having a cutout surrounded by the cover  64  to permit passage therethrough of the link  67  that carries the second media arm  63  on its distal end and which is connected to the output shaft  68  of drive unit  62  for example by a splined connection. Output shaft  68  penetrates cover  64  from below via a sealed bearing, thus drive unit  62  is disposed outside the chamber and is protected from the harsh chemical environment that exists within the chamber. 
         [0073]    Thus, when drive unit  62  is actuated, link  67  will be pivoted over a range of motion dictated by the operating cycle of the drive unit  62 , and which corresponds to displacement of the media supply arm  63  from its standby position to its service position. The size of the cutout in the cylindrical chamber wall  30  is therefore sized to accommodate that range of pivotal motion. 
         [0074]    Lead-in  66  connects to the second media line  61  inside the chamber. Lead-in  66  may for example be a fluid coupling that traverses the cylindrical wall  30  of the chamber in a sealed manner, connecting to inlet tubing at its end outside the chamber and to second media line  61  at its end inside the chamber. 
         [0075]    Also visible in  FIG. 14  is an interior chamber wall positioned radially inwardly of cylindrical chamber wall  30 , which together with wall  30  defines the stowage area  65  for the second media supply arm  63 . That interior wall is provided with a cut-out  69  to permit passage of the downwardly-depending dispensing end of the media supply arm  63  as it is moved from its standby position in stowage area  65  to its service position in which the dispensing end of arm  63  is positioned above the center of the spin chuck. 
         [0076]    It will be appreciated that first and second media supply arms  53  and  63  are equipped with essentially the same drive mechanisms in this embodiment, such that the description of the various components of one unit applies also to the other, although such description might not be repeated herein. Moreover, although the present embodiment of the invention is equipped with two media dispense arms, the number of such arms and their associated drive mechanisms could be only one, or, conversely, could be three or more. 
         [0077]    In  FIG. 15 , the first media arm  53  remains in its standby position, whereas second media supply arm  63  has been pivoted to the service position, in which the downwardly depending dispense nozzle of the arm  63  is positioned above the center of the spin chuck. Second media line  61  is more visible with arm  63  in its service position. That line  61  is depicted schematically in  FIG. 15 , but it will be seen that the length of line  61  is sufficient to accommodate the range of motion of the radially inward end of link  67 , and so too its flexibility. 
         [0078]    The perspective view of  FIG. 16  corresponds to  FIG. 15  and shows cover  54  in place whereas cover  64  is removed to reveal the drive linkage for media arm  63 . 
         [0079]    In use, the chamber will be opened to permit loading a wafer to be processed therein. This involves first actuating the motor  28 , which is fixed by posts to the underside of base plate  15  and stationary relative thereto (see  FIG. 3 ), but whose output shaft when extended causes lead-in  29  to be displaced upwardly, and with it the shaft  18 , lid arm  22  and lid  100 . Shaft  18  is preferably journaled in the lead-in  29  such that it is raised with the lead-in, but is rotatable relative to the lead-in  29 . 
         [0080]    Once the lid  100  has been raised to open the chamber, motor  27  is next actuated to drive link  19  in an arcuate range of motion about the axis of shaft  18 . As link  19  is non-rotabably secured to shaft  18 , this motion rotates shaft  18  and with it lid arm  22  and lid  100 , such that the lid  100  is swung away from the opening defined by the upper annular chamber cover  32 , to the position shown in  FIG. 2 . As shown in  FIG. 3 , motor  27  is itself mounted to the underside of base plate  15  via a pivot, to allow the pivotal motion of the link  19 . Link  19  may be splined to shaft  18  and slide relative thereto during vertical displacement of shaft  18  driven by motor  28 , or link  19  may be secured fast to shaft  18 , and be driven by motor  27  at its opposite end via a pivot connection on which it may slide vertically when motor  28  is operated. 
         [0081]    After the chamber has been opened as shown in  FIG. 2 , a wafer to be processed is loaded therein. Apparatus for transporting and loading wafers onto spin chucks are well known in the art. To receive a wafer, motor  76  is actuated to raise the spin chuck  70  via slider  74  to a position in the vicinity of the opening defined in the upper annular chamber cover  32 . In particular, the spin chuck  70  may be raised to a position where it is just below the opening in cover  32 , just above that opening, or flush with that opening. 
         [0082]    It will be noted that the diameter of the opening in the upper annular cover  32  must obviously be greater than the outer diameter of a wafer to be processed in the chamber, but is preferably not of substantially greater diameter. For example, in the case of a 300 mm silicon wafer, the opening in cover  32  preferably has a diameter of approximately 320 mm. In general, the diameter of the opening in the upper end of the chamber should not exceed the diameter of a wafer to be processed by more than 50%, preferably by not more than 20%, and still more preferably by not more than 10%. 
         [0083]    Spin chuck  70  is adapted to hold a wafer of a predetermined diameter, in this case 300 mm. Spin chuck  70  includes a peripheral series of gripping pins, which prevent the wafer from sliding laterally during processing. When spin chuck  70  is implemented as a Bernoulli chuck, a nitrogen gas flow supplied through the chuck and passing radially outwardly beneath the wafer provides the subjacent support of the wafer. Alternatively, the gripping pins may be configured with radially inwardly-facing surfaces that hold the wafer in its working position relative to the chuck, e.g. by having a shape complementary to the peripheral edge of the wafer, thereby providing both lateral and subjacent support. 
         [0084]    Spin chuck  70  is then lowered by motor  76  to a working position at one of the upper, middle and lower levels  34 ,  35 ,  36 , whereafter spin motor  72  commences to spin the spin chuck  70 . Any desired combination of liquids and gases can then be supplied to the chamber interior, the liquids via media supply arms  53 ,  63  and the gases via lid  100 . 
         [0085]    It is preferred that one or more of the seals that seal the chamber be designed so as to permit controlled leakage of gas exteriorly of the chamber at a predetermined level of overpressure. In that way, a substantially oxygen-free atmosphere can be maintained within the chamber during processing of a wafer, while continuing to supply gas from lid  100  and/or through the shaft  78  without accumulation of excess pressure. This design also permits exclusion of oxygen without the need to rely upon the use of vacuum or the maintenance of completely impervious seals. 
         [0086]    It will be appreciated that the design of this embodiment permits the lid and the media supply arms to supply gas and liquid simultaneously to the chamber interior. Furthermore, the design of the media supply arms  53 ,  63  and their associated drive mechanisms permits the arms to be disposed inside the chamber whereas their respective drive units are mounted outside the chamber. This provides the considerable advantage of preventing exposure of those drive units to the very aggressive chemicals often used in such processing modules. 
         [0087]    While the present invention has been described in connection with various illustrative embodiments thereof, it is to be understood that those embodiments should not be used as a pretext to limit the scope of protection conferred by the true scope and spirit of the appended claims.