Patent Publication Number: US-2015075569-A1

Title: Barrier structure and nozzle device for use in tools used to process microelectronic workpieces with one or more treatment fluids

Description:
PRIORITY CLAIM 
     This application is a divisional of patent application Ser. No. 13/219,220, filed Aug. 26, 2011, now U.S. Publication No. 2011-0308647, and entitled BARRIER STRUCTURE AND NOZZLE DEVICE FOR USE IN TOOLS USED TO PROCESS MICROELECTRONIC WORKPIECES WITH ONE OR MORE TREATMENT FLUIDS, which is a continuation of patent application Ser. No. 12/217,883, filed Jul. 9, 2008, now U.S. Publication No. 2008-0271763, and entitled BARRIER STRUCTURE AND NOZZLE DEVICE FOR USE IN TOOLS USED TO PROCESS MICROELECTRONIC WORKPIECES WITH ONE OR MORE TREATMENT FLUIDS, which is a divisional of patent application Ser. No. 11/376,996, filed Mar. 15, 2006, now U.S. publication No. 2007-0245954-A1, and entitled BARRIER STRUCTURE AND NOZZLE DEVICE FOR USE IN TOOLS USED TO PROCESS MICROELECTRONIC WORKPIECES WITH ONE OR MORE TREATMENT FLUIDS, wherein the respective entireties of said nonprovisional applications are incorporated herein by reference and wherein said nonprovisional applications claim priority under 35 USC §119(e) from U.S. Provisional Patent Applications having Ser. No. 60/667,263, filed on Apr. 1, 2005, by Collins et al. and titled COMPACT DUCT SYSTEM INCORPORATING MOVEABLE AND NESTABLE BAFFLES FOR USE IN TOOLS USED TO PROCESS MICROELECTRONIC WORKPIECES WITH ONE OR MORE TREATMENT FLUIDS and Ser. No. 60/667,369, filed on Apr. 1, 2005, by Rose et al. and titled COMPACT DUCT SYSTEM INCORPORATING MOVEABLE AND NESTABLE BAFFLES FOR USE IN TOOLS USED TO PROCESS MICROELECTRONIC WORKPIECES WITH ONE OR MORE TREATMENT FLUIDS, wherein the respective entireties of said provisional patent applications are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to barrier plates and dispense assemblies for tools used to process microelectronic substrates with one or more treatment fluids, including liquids and gases. More particularly, the present invention relates to such tools that include movable and nestable baffle members that that can be positioned to open and close, and help define the boundaries of, one or more ducts for collecting and recovering the treatment fluids that are used. 
     BACKGROUND OF THE INVENTION 
     The microelectronic industry relies on a variety of different processes to manufacture microelectronic devices. Many processes involve a sequence of treatments in which different kinds of treatments fluids are caused to contact the workpiece in accordance with desired recipes. These fluids may be liquids, gases, or combinations thereof. In some treatments, solids may be suspended or dissolved in a liquid or entrained in a gas. It is highly desirable to capture and recover these treatment fluids for a variety of reasons including proper disposal, recycling, fume containment, process monitoring, process control, or other handling. 
     One capture technique involves using appropriately positioned ducts to capture treatment fluids. For instance, a typical manufacturing tool in the microelectronics industry involves supporting one or more workpieces in a processing chamber on a suitable support, such as a stationary platen, rotating turntable, or rotatable chuck. One or more ducts are positioned at least partially around the outer periphery of the support. As a treatment fluid is introduced into the processing chamber, an exhaust can be used to help pull the treatment fluid into the one or more ducts. With respect to rotating supports, centrifugal force causes fluids on a spinning workpiece and/or support surface to flow radially outward from the spin axis and into the duct(s). 
     Conventionally, a tool may include a single duct to capture different treatment fluids. However, using a single duct like this is not desirable in all instances. For example, some treatment fluids may be too reactive in the presence of other treatment materials. Other times, it may be desirable to capture different fluids using different capture conditions. Still other times, such as when recycling is desired, it may be desirable to capture a fluid in a dedicated duct to avoid contamination with other fluids. 
     Accordingly, tools containing multiple, stacked ducts, fixed relative to each other, have been used. Either the workpiece support and/or the stacked ducts themselves are raised and lowered in order to bring the appropriate duct into position. This conventional approach suffers from serious drawbacks. The stacked ducts make high-density tool packaging more difficult. The different ducts may also be subject to cross-contamination because they are always open to the workpiece and/or exhaust levels are not individually controlled. Some conventional duct systems also may not have the capability to separate the liquid and gas constituents of an exhaust stream. In some tools in which the duct structures themselves are moveable, drain and exhaust connections to external plumbing must also move, thereby adding undue complexity to tool design, manufacture, use, and service. 
     There is a continuing need, therefore, in the microelectronics industry to provide compact tools that nonetheless incorporate multiple ducts for capturing different kinds of treatment fluids. 
     SUMMARY OF THE INVENTION 
     The present invention provides a novel duct system for use in tools in which microelectronic workpieces are treated with treatment fluids, including liquids, gases, fluidized solids, dispersions, combinations of these and the like. The ducts are used to capture the various treatment fluids for recycling, discarding, or other handling. Different treatment fluids can be recovered in different, independent ducts to minimize cross-contamination and/or to use unique capture protocols for different fluids. 
     The duct system of the present invention is extremely compact. The duct system is defined at least in part by moveable and nestable duct structures in which portions of duct pathways may exist between these structures and/or between these and other structures in the tool. For example, when the structures are moved apart relatively, a duct pathway opens and is enlarged between the structures. When the structures are moved together relatively, the duct between the structures is choked and is reduced in size. In preferred embodiments, multiple ducts can exist in the same volume of space depending upon how the moveable duct structures are positioned. Thus, multiple ducts can occupy a volume minimally larger than the volume occupied by only a single duct. 
     The moveable duct structures are preferably fluidly coupled to fixed duct structures so that drain and exhaust connections between the tool and external plumbing are fixed and need not move. 
     In one aspect, the present invention relates to an apparatus for processing a microelectronic workpiece. The apparatus includes a support on which the workpiece is positioned during a process. The apparatus also includes a plurality of moveable and nestable baffle members defining at least portions of a plurality of duct pathways having respective duct inlets proximal to an outer periphery of the workpiece. 
     In another aspect, the present invention relates to an apparatus for processing a microelectronics workpiece. The apparatus includes a rotatable support on which the workpiece is positioned during a process. The apparatus also includes a plurality of moveable baffle members defining at least a first duct pathway between the baffle members and having an inlet proximal to an outer periphery of the rotatable workpiece. Displacement of the baffle members relative to each other opens and chokes at least the first duct pathway. 
     In another aspect, the present invention relates to an apparatus for processing a microelectronic workpiece. The apparatus includes a housing and a rotatable support positioned in the housing and onto which the workpiece is positioned for processing. The apparatus includes a plurality of duct pathways having respective inlets proximal to an outer periphery of the rotatable workpiece. Each duct pathway is defined at least in part by structures comprising a plurality of fixed duct structures that are relatively distal from the rotatable workpiece and a plurality of independently moveable baffle members that are relatively proximal to the rotatable workpiece and that define duct pathway portions that are fluidly coupled to respective fixed duct structures. 
     In another aspect, the present invention relates to an apparatus for processing a microelectronic workpiece. The apparatus includes a processing chamber in which the workpiece is positioned during a process. A barrier structure overlies and covers the workpiece in a manner effective to help provide a tapering flow channel proximal to a major surface of the workpiece. 
     In another aspect, the present invention relates to a method of processing a microelectronic workpiece. The workpiece is positioned in a processing chamber. A barrier structure overlies and covers the workpiece in a manner effective to help provide a tapering flow channel proximal to a major surface of the workpiece that tapers in a radially outward direction relative to said surface. While the workpiece is positioned in the processing chamber and covered by the barrier structure, at least one processing material is caused to flowingly contact said major surface of the workpiece. 
     In another aspect, the present invention relates to an apparatus, comprising a processing chamber in which the workpiece is positioned during a process. A barrier structure overlies and covers the workpiece in a manner effective to help provide a tapering flow channel proximal to a major surface of the workpiece that tapers in a radially outward direction relative to said surface. The barrier structure is controllably moveable through a range of motion including a first position in which the processing chamber is sufficiently open to allow workpiece transfer to and from the processing chamber and a second position in which the barrier structure helps to guide at least one material flowing over said major surface. 
     In another aspect, the present invention relates to a nozzle device comprising an annular body having a lower surface that is angled so as to help define a tapering flow channel over a workpiece surface when the body is positioned over the workpiece surface. At least one nozzle is integrated with the annular body in a manner effective to dispense one or more processing materials downward onto the workpiece surface. The annular body includes one or more processing material supply conduits through which one or more processing materials are supplied to the at least one nozzle. 
     In another aspect, the present invention relates to a nozzle device comprising an annular body having a lower surface that is angled so as to help define a tapering flow channel over a workpiece surface when the annular body is positioned over the workpiece surface. The annular body comprises an inner periphery defining a central pathway that provides egress between a volume above the annular body and a volume below the annular body. An arm structure is coupled to the annular body and extends generally across the central pathway in a manner effective to help define first and second pathway portions. At least a first, independent array of nozzles is integrated with the annular body in a manner such that the first array extends at least partially along the arm structure and a first radius of the annular body in a manner effective to dispense one or more processing materials downward onto the workpiece surface. At least one independent nozzle is integrated into the central arm in a manner effective to dispense one or more processing materials downward onto a central portion of the workpiece. At least one independent nozzle is positioned to dispense one or more processing materials onto the workpiece from a flow path that extends through at least one of the central flow pathway portions. 
     In another aspect, the present invention relates to a nozzle device comprising a first nozzle structure through which one or more processing materials independently are atomizingly dispensed onto a workpiece surface across at least a portion of a radius of the workpiece surface; a second nozzle structure is provided through which one or more processing materials independently are dispensed onto a central portion of the workpiece surface; and a third nozzle structure through which one or more processing materials are independently introduced into a headspace above the workpiece surface. The first, second and third nozzle structures are moveable relative to the workpiece surface. 
     In another aspect, the present invention relates to an apparatus for processing a microelectronic workpiece. The apparatus includes a processing chamber in which the workpiece is positioned during a process and a moveable member comprising a tube portion having a through bore. The moveable member is positioned over the workpiece and is moveable relative to a major surface of the workpiece. At least one independent nozzle structure is physically coupled to the moveable member such that movement of the moveable member allows the relative spacing between the major surface of the workpiece and the nozzle structure to be controllably adjusted. At least a portion of at least one fluid supply pathway in the through bore of the tube portion is fluidly coupled to the at least one independent nozzle structure and workpiece. 
     In another aspect, the present invention relates to an apparatus for processing a microelectronic workpiece. The apparatus includes a processing chamber in which the workpiece is positioned during a process and a ceiling structure overlying the processing chamber in a manner effective to provide a first zone relatively distal from the processing chamber and a second zone relatively proximal to the processing chamber. The ceiling structure comprises a walled conduit providing egress between the first and second zones. A moveable member is housed in the walled conduit. The member comprises at least a tube portion having a first port to provide egress into the through bore from the first zone. The moveable member is moveable relative to the walled conduit and with respect to the workpiece. A nozzle structure is coupled to the moveable member in a manner such that the nozzle structure is positionable to dispense one or more processing materials into the processing chamber. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an isometric view of a preferred tool embodiment of the present invention. 
         FIG. 2  shows an isometric, cross-sectional view of a portion of the tool of  FIG. 1  taken along line A-A in which the tool is in a configuration in which an inner duct pathway is open and the shutter is lowered/closed. 
         FIG. 3  shows an isometric, cross-sectional view of a portion of the tool of  FIG. 1  taken along line B-B in which the tool is in a configuration in which an inner duct pathway is open and the shutter is raised/open. 
         FIG. 4  shows an isometric, cross-sectional view of a portion of the tool of  FIG. 1  taken along line B-B in which the tool is in a configuration in which a middle duct pathway is open. 
         FIG. 5  shows an isometric, cross-sectional view of a portion of the tool of  FIG. 1  taken along line B-B in which the tool is in a configuration in which an outer duct pathway is open. 
         FIG. 6  shows an isometric cross-sectional view of the tool of  FIG. 1  taken along line A-A in which the tool is in a workpiece transfer configuration. 
         FIG. 7  shows an isometric cross-sectional view of the tool of  FIG. 1  taken along line B-B in which the tool is in a workpiece transfer configuration. 
         FIG. 8  is an isometric view of the bottom of the tool of  FIG. 1 . 
         FIG. 9  is an alternative isometric view of the bottom of the tool of  FIG. 1 . 
         FIG. 10  is an isometric view of the base pan of the tool of  FIG. 1  with components removed to show a series of annular, concentric walls rising upward from the bottom of the base pan to define a plurality of exhaust plenums and drain basins. 
         FIG. 11  is an isometric view of the drip ring used in the tool of  FIG. 1 . 
         FIG. 12  is an isometric view of the outer, annular baffle plate used in the tool of  FIG. 1  (The middle and inner baffle plates are not shown but are similar except for being sized to nest inside each other as shown in other Figures and described further herein.). 
         FIG. 13  is an isometric view of the outer baffle hood used in the tool of  FIG. 1  (The middle and inner baffle hoods are not shown but are similar except for being sized to nest inside each other as shown in other Figures and described further herein.). 
         FIG. 14.A  is a close-up, cross-sectional view of a portion of the tool of  FIG. 1  taken along line B-B that generally identifies the area around the annular drip ring. 
         FIG. 14.B  is a close-up, cross-sectional view of a portion of the tool of  FIG. 1  taken along line B-B that generally identifies the area around the inner baffle member. 
         FIG. 14.C  is a close-up, cross-sectional view of a portion of the tool of  FIG. 1  taken along line B-B that generally identifies the area around the middle baffle member. 
         FIG. 14.D  is a close-up, cross-sectional view of a portion of the tool of  FIG. 1  taken along line B-B that generally identifies the area around the outer baffle member. 
         FIG. 14.E  is a close-up, cross-sectional view of a portion of the tool of  FIG. 1  taken along line B-B that generally identifies exhaust plenums and drain basins. 
         FIG. 15  is another close-up, cross-sectional view of a portion of the tool of  FIG. 1  taken along line B-B. 
         FIG. 16  is a cross-sectional view of a portion of the tool of  FIG. 1  taken along line B-B. 
         FIG. 17  shows an isometric, cross-sectional view of a portion of the tool of  FIG. 1  taken along line A-A in which the tool is in a configuration in which the dispense assembly is lowered to carry out a treatment and the shutter is lowered/closed. 
         FIG. 18  shows an isometric view of the ceiling plate used in the tool of  FIG. 1 . 
         FIG. 19  shows an isometric view of the moveable support member used in the tool of  FIG. 1 . 
         FIG. 20  is a cross-sectional view of a portion of the tool of  FIG. 1  taken along line C-C of  FIG. 8  showing actuator parts for the outer and inner baffle members. 
         FIG. 21  is an isometric view of the dispense assembly used in the tool of  FIG. 1 . 
         FIG. 22.A  is a cross-sectional, isometric view of the dispense assembly of  FIG. 21  taken along line G-G. 
         FIG. 22.B  is a cross-sectional, isometric view of the dispense assembly of  FIG. 21  taken along line G-G that is similar to  FIG. 22.A  except for identifying additional reference characters. 
         FIG. 23  is an isometric view of the spray nozzle/barrier structure used in the dispense assembly of  FIG. 22  looking generally at the underside of the structure. 
         FIG. 24  is an isometric view of the spray nozzle/barrier structure used in the dispense assembly of  FIG. 22  looking generally at the top side of the structure. 
         FIG. 25  is a cross-sectional view of the spray nozzle barrier structure of  FIG. 24  taken along line H-H. 
         FIG. 26  is a cross-sectional view of the spray nozzle barrier structure of  FIG. 24  taken along line J-J. 
         FIG. 27  is an isometric view of the central dispense nozzle member used in the dispense assembly of  FIG. 22 . 
         FIG. 28  is an isometric view of the retainer/spacer clamp used in the dispense assembly of  FIG. 22 . 
         FIG. 29  is an isometric view of a portion of the dispense assembly of  FIG. 22  including the central dispense nozzle and retainer/spacer clamp subassembly. 
         FIG. 30  is a cross-sectional, isometric view of the subassembly of  FIG. 29  taken along line D-D. 
         FIG. 31  is a cross-sectional, isometric view of the subassembly of  FIG. 29  taken along line C-C. 
         FIG. 32  is an isometric view of the showerhead dispense assembly used in the dispense assembly of  FIG. 22 , looking generally at the top side of the assembly. 
         FIG. 33  is an isometric view of the showerhead dispense assembly of  FIG. 22  looking generally at the bottom side of the assembly. 
         FIG. 34  is an isometric view of the base used in the showerhead dispense assembly of  FIG. 32 . 
         FIG. 35  is an isometric view of the cover used in the showerhead dispense assembly of  FIG. 32 . 
         FIG. 36  is an isometric view of a mounting standoff used in the dispense assembly of  FIG. 22 . 
         FIG. 37  is a cross-sectional view of a portion of the tool of  FIG. 1  taken along line A-A showing the nesting relationship among the moveable support member, the shutter, and the ceiling plate. 
         FIG. 38  is an isometric view of the shutter used in the tool of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF PRESENTLY PREFERRED EMBODIMENTS 
     The embodiments of the present invention described below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather the embodiments are chosen and described so that others skilled in the art may appreciate and understand the principles and practices of the present invention. While the present invention will be described in the specific context of fluid based microelectronic substrate cleaning systems, the principles of the invention are applicable to other microelectronic processing systems as well. 
       FIGS. 1 through 38  show an illustrative tool  10  that incorporates principles of the present invention. For purposes of illustration, tool  10  is of the type in which a single workpiece  12  is housed in the tool  10  at any one time and subjected to one or more treatments in which liquid(s) and/or gas(es) are caused to contact the workpiece  12 . In the microelectronics industry, for instance, tool  10  may be referred to as a single wafer processing tool. Workpiece  12  is typically a semiconductor wafer or other microelectronic substrate. 
     Tool  10  generally includes as main assemblies processing section  11  and barrier dispense section  500 . In actual use, the dispense section  500  and processing section  11  would be mounted to a framework (not shown) and enclosed within a housing (not shown) of tool  10 . This mounting can occur in any manner such as via screws, bolts, rivets, adhesives, welds, clamps, brackets, combinations of these, or the like. Desirably, though, the sections  11  and  500  and/or components thereof are independent and removably mounted to facilitate service, maintenance, upgrade, and/or replacement. 
     Processing section  11  generally includes a base  14  formed at least in part by base pan  16  and peripheral sidewall  18 . Base pan  16  and sidewalls  18  may be formed from parts that are screwed, bolted, glued, welded, or otherwise attached to each other. Alternatively, base pan  16  and sidewalls  18  may be integrally formed as one part as is shown. 
     In this particular preferred embodiment, three pairs of annular, generally concentric walls  22  and  23 ,  24  and  25 , and  26  and  27  project upward from base pan  16 . These walls help to define exhaust plenums  29 ,  30 , and  31  and drain basins  52 ,  53 ,  54  and  55 . The exhaust plenums  29 ,  30 , and  31  and the drain basins  52 ,  53 , and  54  form portions of three independent, nested exhaust duct pathways  330 ,  338 , and  346  to be discussed further below. Of course, other representative embodiments of the invention may include a lesser or greater number of such ducts as desired in which case a lesser or greater number of exhaust plenums and drain basins would be provided, as appropriate. 
     Also in the embodiment of tool  10  as shown, the ducts  330 ,  338 , and  346  preferably are independent and discrete from each other in that each such duct has its own exhaust plenum(s) and drain basin(s). Advantageously, this allows individual exhaust streams to be separately handled at the exhaust and/or other stage(s) of processing. This may be desirable for a variety of reasons. For instance, it may be desirable to recover liquid constituents of an exhaust stream for recycling. Use of a dedicated exhaust duct for such liquid constituents avoids cross-contamination with other streams. In other instances, it may be desirable to exhaust different streams under different conditions. The use of independent and discrete exhaust duct pathways thus is preferred in many instances. However, in other embodiments, especially where an even more compact design is desired, two or more exhaust ducts may share a drain basin and/or an exhaust plenum. 
     The top rims  33  and  34  of walls  22  and  23  define a generally annular exhaust inlet  35  by which an exhaust stream enters inner exhaust plenum  29 . The bottom of exhaust plenum  29  includes one or more exhaust outlet ports  48  through which an exhaust stream exits inner exhaust plenum  29 . In similar fashion, the top rims  38  and  39  of walls  24  and  25  define an annular exhaust inlet  40  by which an exhaust stream enters middle exhaust plenum  30 . The floor of plenum  30  includes one or more exhaust outlet ports  49  through which an exhaust stream exits middle exhaust plenum  30 . Also in similar fashion, the top rims  43  and  44  of walls  26  and  27  define an annular exhaust inlet  45  by which an exhaust stream enters outer exhaust plenum  31 . The floor of plenum  31  includes one or more exhaust outlet ports  50  through which an exhaust stream exits outer exhaust plenum  31 . 
     Each drain basin  52 ,  53 ,  54 , and  55  respectively includes a floor  56 ,  57 ,  58 , and  59 . Each of floors  56 ,  57 ,  58 , and  59  respectively includes one or more drain outlets such as outlets  63  and  67  through which collected liquid exits the corresponding drain basin. The floor  56  of inner drain basin  52  is appropriately sloped to direct collected liquid to drain outlet(s)  63 . Floors  57 ,  58 , and  59  may be sloped in a similar manner. The various drain outlets are fitted with drain couplings  62  or  68  to facilitate connection to suitable drain plumbing (not shown). 
     In the preferred embodiment as shown, a plurality of actuator shaft housings  69  including shaft bores  70  are positioned in inner exhaust plenum  29 . These essentially subdivide inner exhaust plenum  29  into three sub-plenums. To facilitate uniform exhaust flow through the entirety of exhaust plenum, it is therefore desirable to provide one or more exhaust ports in each of such sub-plenums. Shaft housings  69  and bores  70  provide access for actuator shafts  314  to be coupled to and thereby control movement of inner baffle member  174  that operationally engages inner exhaust plenum  29 . In similar fashion, actuator shaft housings  73  including shaft bores  72  are positioned in middle exhaust plenum  30  and provide access for actuator shafts (not shown) to be coupled to and thereby control movement of middle baffle member  218  that operationally engages middle exhaust plenum  30 . Also in similar fashion, actuator shaft housings  75  including shaft bores  76  are positioned in outer exhaust plenum  31  and provide access for actuator shafts  326  to be coupled to and thereby control movement of outer baffle member  262  that operationally engages outer exhaust plenum  31 . 
     The central area of base pan  16  includes central through bore  78 . Central through bore  78  preferably is generally circular in cross-section as shown but could also be provided with other geometries as desired. Cylindrical inner flange  80  projects upward from base pan  16  and helps to define cylindrical inner sidewall  82  and outer sidewall  84 . Outer sidewall  84  includes shoulder  90  at its top rim, and inner sidewall  82  includes a shoulder  92  at its lower rim. 
     Inside processing chamber  503 , workpiece  12  is supported and held by chuck  94 . Chuck  94  is generally cylindrical in shape and includes an upper face  96 , lower face  98 , annular base  100 , central through bore  102 , sidewall  104  at the outer periphery, and annular splash shield  108 . Chuck  94  may be stationary or it may be rotatable about a central axis  106 . For purposes of illustration, the figures illustrate an embodiment of tool  10  in which chuck  94  is rotatably driven by motor  110  so that workpiece  12  may be spun about axis  106  during a treatment. In those embodiments in which workpiece  12  is spun by a rotating chuck  94 , the spinning helps to spread dispensed treatment materials uniformly over the workpiece  12 . Motor  110  may be of the hollow shaft type having central bore  112  and is mounted to tool  10  by any convenient approach such as by mounting structures  114 . 
     Annular splash shield  108  extends downward from lower face  98  of chuck  94 . Lower end  109  of shield  108  is nested in shoulder  90  of inner flange  80  and helps to prevent liquids from splashing over inner flange  80  and then into central through bore  78 . In embodiments in which chuck  94  is rotatable, there is a gap between shield  108  and the walls of shoulder  90  to avoid having the shield  108  and shoulder walls rub against each other, which could generate undesirable debris as the chuck  94  rotates. 
     Chuck  94  may secure workpiece  12  in any of a variety of different ways in accordance with conventional practices now or hereafter developed. Preferably, chuck  94  includes edge gripping structures (not shown) that securely hold workpiece  12  above upper face  96  of chuck  94  such that there is a gap between workpiece  12  and the upper face  96 . Thus, treatment chemicals, including rinse water, may be dispensed onto either upper face  128  or lower face  130  of workpiece  12 . 
     Optionally, tool  10  may include dispense structure(s) for treating the lower face  130  of workpiece  12 . An illustrative backside dispense mechanism is shown as a generally circular dispense head  136  in which one or more treatment chemicals may be dispensed toward lower face  130  of workpiece  12  through a plurality of nozzle orifices (not shown). Treatment chemicals are supplied to backside dispense head  136  via shaft  138  that passes through central bore  102  of chuck  94  and central bore  112  of motor  110 . In embodiments in which chuck  94  rotates, there are gaps in between shaft  138 , and central bores  102  and  112  so that the parts do not rub as the chuck  94  rotates. The backside dispense head  136  may be coupled to one or more supplies (not shown) of treatment materials to be dispensed as supplied or blended on demand. 
     Annular drip ring  156  is fitted to base pan  16  proximal to inner flange  80 . Drip ring  156  generally includes floor  158 , inner wall  160 , middle wall  162 , curved top rim  164 , and outer wall  166 . Floor  158  cants downward to generally match the slope of and fit against floor  56  in drain basin  52 . Inner wall  160  of drip ring  156  is fitted against lower sidewall portion  86  of inner flange  80 . Middle wall  162  jogs outward so that there is a gap between middle wall  162  and the sidewall  104  of chuck  94 . Curved top rim  164  provides a smooth transition between middle wall  162  and outer wall  166 . This helps promote a smooth flow when an exhaust stream flows over drip ring  156  and into one or more open ducts to be described further below. Curved top rim  164  in this embodiment projects slightly above the upper face  96  of chuck  94 . In this way, some liquid spun outward from chuck  94  and/or workpiece  12  is caught in catch basin  170  formed by drip ring  156 . Drain ports  172  are provided in the lower portion of drip ring  156  formed by floor  158  and middle wall  162  to allow liquid collected in catch basin  170  to drain into drain basin  52 . 
     Tool  10  further includes a plurality of moveable and nestable baffle members  174 ,  218 , and  262  generally corresponding to the number of exhaust plenums  29 ,  30 , and  31  in this particular preferred embodiment. The baffle members  174 ,  218 , and  262  advantageously can be moved independently relative to each other to selectively and controllably open and/or choke one or more exhaust ducts into which exhaust streams may flow radially outward from workpiece  12  and/or chuck  94 . The baffle members  174 ,  218 , and  262  further define at least a portion of the boundaries of such one or more exhaust ducts and thus help guide exhaust streams flowing through the duct(s). The ability of the baffle members  174 ,  218 , and  262  to both move and nest together as desired allows tool  10  to be more compact in that the portions of multiple ducts whose boundaries are at least in part defined by these baffle members can occupy very nearly the same volume in space as only a single duct. Compactness is important for a variety of reasons, including lower required stack height, easier packaging, lesser tool dimensions, and the like. 
     Inner baffle member  174  generally includes annular baffle plate  176  and annular baffle hood  194 . Although plate  176  and hood  194  can be formed as a single, unitary part, it is preferred that these be separate parts that are fastened or otherwise secured together to ease assembly, maintenance, and service of tool  10 . Annular baffle plate  176  has upper surface  178 , lower surface  180 , inner rim  182  proximal to the outer periphery of chuck  94 , outer sidewall flange  186 , and inner sidewall flange  190 . The surfaces among the components of annular baffle plate  176  are connected by smooth transitions to promote smooth exhaust flows over and/or under inner baffle member  174 . The double wall structure provided by outer sidewall flange  186  and inner sidewall flange  190  provides multiple functions. As one function, these flanges  186  and  190  provide a secure, rigid way to secure annular baffle plate  176  to corresponding annular baffle hood  194 . For any of the baffle members  174 ,  218 , or  262 , the respective baffle plate may be attached to the corresponding hood in any desired manner. Preferred approaches are non-permanent so that the parts can be easily separated and replaced after service and maintenance. Using both flanges  186  and  190  also makes it easier to define smooth flow pathways both above and below inner baffle member  174 , as desired. 
     Annular baffle hood  194  fits over and enshrouds exhaust inlet  35  of exhaust plenum  29 . Inner baffle member  174  is translatable up and down so that corresponding movement of hood  194  up and down opens and chokes, to the desired degree, the exhaust inlet  35 . Additionally, hood  194  includes structure that helps provide drain trap functionality in drain basin  52 . This helps to separate liquid and gas constituents of exhaust streams that flow through drain basin  52 . Such separated constituents may be independently recovered for disposal, recycling, further reaction, or other handling as desired. As an additional function, hood  194  helps to fluidly couple exhaust plenum  29  with a portion of the duct pathway whose boundaries are further defined at least in part by the lower surface  180  of annular baffle plate  176 . 
     In more detail, annular baffle hood  194  includes cap plate  196 , inner flange  198 , outer flange  206 , lower end  202 , and inner surface  204 . Cap plate  196  is generally positioned over exhaust inlet  35  and helps to define a headspace  208  over exhaust inlet  35 . As inner baffle member  174  is lowered, the volume of headspace  208  is reduced as cap plate approaches and thereby chokes flow entering exhaust inlet  35 . Inner baffle member  174  desirably can be lowered far enough so that cap plate  196  seats against and closes exhaust inlet  35 . As inner baffle member  174  is raised, the volume of headspace  208  over exhaust inlet  35  is increased as cap plate  196  moves away from and thereby increases flow access to exhaust inlet  35 . 
     Inner flange  198  is spaced apart from annular wall  22  to provide a flow channel  200  fluidly coupling drain basin  52  to headspace  208 . The lower end of inner flange  198  extends below rims  33  and  34  that help define exhaust inlet  35  to exhaust plenum  29 . In this way, inner flange  198  forms a barrier that blocks exhaust streams that enter the drain basin  52  from flowing directly into exhaust plenum  29 . Instead, such a stream must flow downward toward floor  56 , around the lower end of inner flange  198 , and then upward through the flow channel  200  before gaining access to exhaust inlet  35  via headspace  208 . Thus, the positioning and configuration of inner flange  198  helps provide trap functionality within drain basin  52 . Liquid constituents in an exhaust stream flowing through drain basin  52  will have a relatively greater tendency to collect within drain basin  52 , while gaseous constituents will have a relatively greater tendency to flow through drain basin  52  and into exhaust plenum  29 . 
     To help promote this trap functionality, the inner surface of inner flange  198  is provided with surface features that help promote condensation or other collection of liquid upon the inner surface. The liquid collected in this way then drips or otherwise flows downward to floor  56 , where the liquid can be recovered via drain port(s)  63  for further handling. Preferred surface features as shown include an array of triangular protuberances  210 . Each triangular protuberance  210  is oriented so that its apex  212  is upward (facing the incoming exhaust flow) while the base  214  is downward (away from the incoming flow). The relatively sharp apex  212  confronting the incoming exhaust flow is believed to enhance liquid collection. Generally, using a greater number of these protuberances  210  is desired to facilitate liquid trapping. However, the density of these features on the inner flange  198  is such that the bases  214  of the triangular protuberances  210  are spaced apart sufficiently so that liquid collected on the sides of the protuberances can readily drip or flow downward to floor  56 . 
     Outer flange  206  extends downward and is sufficiently close to annular wall  23  to substantially prevent exhaust from flowing between outer flange  206  and annular wall  23 . To minimize the risk of generating debris due to rubbing contact, there preferably is a small gap between annular wall  23  and outer flange  206 . When an exhaust is being pulled through exhaust plenum  29 , this close gap spacing provides a sufficiently high resistance to flow such that substantially all the exhaust will be pulled through plenum  29 . 
     Middle baffle member  218  is similar to inner baffle member  174  and includes annular baffle plate  220  and annular baffle hood  238 . Annular baffle plate  220  includes upper surface  222 , lower surface  224 , inner rim  226 , outer flange  230 , and inner flange  234 . Annular baffle hood  238  includes cap plate  240  helping to define headspace  252 , inner flange  242  helping to define a flow path through flow channel  244  and having lower end  246  and inner surface  248 , outer flange  250 , and triangular protuberances  254  having apexes  256  and bases  258 . Hood  238  of middle baffle member  218  operationally enshrouds middle exhaust plenum  30  and helps to provide trap functionality within middle drain basin  53 . Additionally, inner baffle member  174  and/or middle baffle member  218  are moveable so that inner baffle member  174  may nest within middle baffle member  218  and thereby variably choke, shut off, or otherwise restrict the flow of a material between the two. Alternatively, the two baffle members  174  and  218  can be separated to variably open a flow path between the two. 
     Outer baffle member  262  is similar to inner baffle member  174  and middle baffle member  218  and includes annular baffle plate  264  and annular baffle hood  282 . Annular baffle plate  264  includes upper surface  266 , lower surface  268 , inner rim  270 , outer flange  274 , and inner flange  278 . Annular baffle hood  282  includes cap plate  284  helping to define headspace  296 , inner flange  286  helping to define a flow channel  288  and having lower end  290  and inner surface  292 , outer flange  294 , and triangular protuberances  298  having apexes  300  and bases  302 . Hood  282  of outer baffle member  262  operationally enshrouds outer exhaust plenum  31  and helps to provide trap functionality within outer drain basin  54 . Additionally, outer baffle member  262  is moveable relative to inner baffle member  174  and/or middle baffle member  218  so that middle baffle member  218  may nest within outer baffle member  262  and thereby variably choke, shut off, or otherwise restrict the flow of a material between the two. Alternatively, the two baffle members  218  and  262  can be separated to variably open a flow path between the two. 
     Tool  10  includes actuating mechanism(s) that independently actuate one or more of baffle members  174 ,  218 , and/or  262  to allow these barriers to be controllably and variably moved and nested relative to each other. Preferred actuating mechanisms for moving baffle members  174  and  262  are shown in the Figures. The actuating mechanisms for middle baffle member  218  would be similar. With respect to inner baffle member  174 , inner baffle actuating motors  312  (motors  318  are used for middle baffle member  218 ) are coupled to corresponding shafts  314  at one end and inner baffle member  174  at the other. The shafts  314  are housed and move up and down within bores  70  of housings  69 . Seals  316  help prevent leaking at these egress areas. Thus, inner baffle member  174  may be moved independently relative to the middle baffle member  218  and outer baffle member  262 . 
     In similar fashion, outer baffle actuating motors  324  are coupled to corresponding shafts  326  at one end and baffle member  262  at the other. The shafts  326  are housed and move up and down within bores  76  of housings  75 . Seals  328  help prevent leaking at these egress areas. Thus, outer baffle member  262  may be moved independently relative to the inner baffle member  174  and middle baffle member  218 . 
     The baffle members  174 ,  218 , and  262  are features of a compact and controllable multi-duct system that can be used to collect and exhaust treatment fluids from processing chamber  503 . One or more of the ducts of the system can be variably opened and/or choked at any one time. In the preferred embodiment depicted in the Figures, each exhaust duct is independent of and discrete from the others. This allows different exhaust protocols to be used with streams exhausted through the different ducts. Also, different treatment materials can be collected in different ducts to facilitate recycling without undue cross-contamination that might otherwise occur if a recycled treatment material were to be recovered from a duct used with other materials. In a typical treatment, one or more kinds of treatment fluids are dispensed onto one or both surfaces of workpiece  12 . When chuck  94 , and hence workpiece  12  rotate, the treatment chemicals tend to flow radially outward and into the appropriate, open exhaust duct(s). Desirably, an exhaust can be pulled through the open duct(s) to help pull materials into the duct(s). Pulling such an exhaust also helps control particles and fumes. A minimal amount of exhaust may be applied to the closed ducts to help prevent cross-contamination. In those embodiments in which the chuck  94 , and hence workpiece  12 , are stationary, pulling an exhaust helps to draw the treatment materials radially outward and into the appropriate exhaust duct(s). 
     It can be appreciated, therefore, that tool  10  has many possible exhaust configurations. For purposes of illustration,  FIGS. 2 through 7  show four representative exhaust configurations that show the versatility of tool  10 .  FIGS. 2 and 3  show tool  10  in an exhaust configuration in which an inner duct pathway  330  is open. In this configuration, all three of baffle members  174 ,  218 , and  262  are raised and nested together. This chokes flow between the members but opens annular duct inlet  332  to duct pathway  330  below inner baffle member  174 . The baffle plates  176 ,  220 , and  264  may be physically touching to choke off flow between the plates, but this can create an undue risk that particles could be generated. Accordingly, it is preferred that the plates  176 ,  220 , and  264  do not physically touch, but nonetheless are sufficiently close enough to create enough flow resistance that substantially the entirety of the exhaust stream flows into the open duct pathway  330 . 
     The annular duct inlet  332  surrounds the outer peripheries of workpiece  12  and chuck  94 . The duct pathway  330  extends radially outward from duct inlet  332  a short distance. Duct pathway  330  then transitions downward to include a more axially oriented flow channel between inner baffle member  174  and outer wall  166  of drip ring  156 . This extends duct pathway  330  into drain basin  52 . The duct pathway  330  continues under hood  194  through flow channel  200 , into headspace  208 , into exhaust plenum  29  via exhaust inlet  35 , and then out through outlet port  36  into suitable plumbing such as inner exhaust manifold  336 . 
       FIG. 4  shows an alternative exhaust configuration of tool  10  in which a middle duct pathway  338  is open. In this configuration, inner baffle member  174  is lowered sufficiently so that flow into the inner duct pathway  330  is choked off. Inner baffle member  174  may physically contact curved top rim  164  of annular drip ring  156 , but it is more preferred that these parts do not touch but are close enough together to choke the flow. At the same time, cap plate  196  seats against and chokes exhaust inlet  35  into inner exhaust plenum  29 . In the meantime, both middle baffle member  218  and outer baffle member  262  are raised with middle baffle member  218  being nested within outer baffle member  262 . This chokes flow between the members but opens annular duct inlet  340  to middle duct pathway  338  above inner baffle member  174  but below middle baffle member  218 . 
     The annular duct inlet  340  surrounds the outer peripheries of workpiece  12  and chuck  94 . The duct pathway  338  extends radially outward from duct inlet  340  a short distance. Duct pathway  338  then transitions downward to include a more axially oriented flow channel between middle baffle member  218  and inner baffle member  174 . This extends duct pathway  338  into drain basin  53 . The duct pathway  338  continues under hood  238  through flow channel  244 , into headspace  252 , into exhaust plenum  30  via exhaust inlet  40 , and then out through outlet port (not shown) into suitable plumbing such as middle exhaust manifold  344 . 
       FIG. 5  shows an alternative exhaust configuration of tool  10  in which an outer duct pathway  346  is open. In this configuration, inner baffle member  174  and middle baffle member  218  are lowered and nested so that plates  176  and  220  are close enough to choke off flow into the inner and middle duct pathways  330  and  338 . At the same time, cap plate  196  seats against and closes exhaust inlet  35  into inner exhaust plenum  29 , and cap plate  240  seats against and closes exhaust inlet  40  into middle exhaust plenum  30 . In the meantime, outer baffle member  262  is raised to thereby open annular duct inlet  348  to outer duct pathway  346  above middle baffle member  218  but below outer baffle member  262 . 
     The annular duct inlet  348  surrounds the outer peripheries of workpiece  12  and chuck  94 . The duct pathway  346  extends radially outward from duct inlet  348  a short distance. Duct pathway  346  then transitions downward to include a more axially oriented flow channel between outer baffle member  262  and middle baffle member  218 . This extends duct pathway  346  into drain basin  54 . The duct pathway  346  continues under hood  282  through flow channel  288 , into headspace  296 , into exhaust plenum  31  via exhaust inlet  45 , and then out through outlet port  46  into suitable plumbing such as outer exhaust manifold  352 . 
       FIGS. 6 and 7  show an alternative exhaust configuration of tool  10  in which duct pathways  330 ,  338 , and  346  are all closed and workpiece  12  may be loaded into and/or taken from processing chamber  503 . In this configuration, inner baffle member  174 , middle baffle member  218 , and outer baffle member  262  are lowered and nested so that plates  176 ,  220 , and  264  are close enough to choke off flow into the inner, middle, and outer duct pathways  330 ,  338 , and  346 . At the same time, cap plate  196  seats against and closes exhaust inlet  35  into inner exhaust plenum  29 , cap plate  240  seats against and closes exhaust inlet  40  into middle exhaust plenum  30 , and cap plate  284  seats against and closes exhaust inlet  45  into outer exhaust plenum  31 . Optionally, barrier plate  556  may be raised to ease access to and from processing chamber  503 . 
     The figures show an illustrative embodiment of one kind of preferred barrier/dispense section  500  useful in dispensing one or more processing materials in the course of processing one or more microelectronic workpieces. The dispense mechanism may be coupled to one or more supplies (not shown) of treatment materials provided via supply lines (not shown). These materials can be dispensed as supplied or blended on demand. A wide variety of treatment materials may be used, as tool  10  is quite flexible in the types of treatments that may be carried out. Just a small sampling of representative treatment materials include gases and liquids such as nitrogen, carbon dioxide, clean dry air, argon, HF gas, aqueous HF, aqueous isopropyl alcohol, deionized water, aqueous ammonia, aqueous sulfuric acid, aqueous nitric acid, hydrogen peroxide, ozone gas, aqueous ozone, organic acids and solvents, combinations of these and the like. Additional representative examples of processes and chemistries suitably practiced in tool  10  include those described in application entitled APPARATUS AND METHOD FOR SPIN DRYING A MICROELECTRONIC SUBSTRATE, attorney docket number FSI0156/US, naming Tracy Gast as one of the inventors, the disclosure of which is fully incorporated herein by reference. 
     Barrier/dispense section  500  includes as major components ceiling plate  504 , moveable support member  526 , dispense assembly  554 , and optional but preferred shutter  818 . Electric, pneumatic, or other suitable actuators (not shown) can be utilized to effect the desired motion of these components. Ceiling plate  504  forms a barrier that helps to define a first zone  506  above ceiling plate  504  and a second zone  508  below ceiling plate  504 . Second zone  508  generally includes headspace  502 , which is generally the volume of second zone  508  above annular body  558 , and processing chamber  503 , which is generally the volume of second zone  508  below annular body  558 . The dimensions of headspace  502  and processing chamber  503  correspondingly change with movement of dispense assembly  554  in z-axis  527 . 
     Ceiling plate  504  includes panel  510  having an outer periphery  512  and an inner periphery  514  defining a generally central through aperture  516 . This aperture  516  may have any desired shape, but preferably is circular as shown. Outer wall  515  extends upward from panel  510  to essentially form a wall around panel  510 . Wall  515  enhances the rigidity of ceiling plate  504 , helps to capture leaks from dispensing components, and provides convenient surfaces by which to mount ceiling plate  504  to its framework/housing. Cylindrical center wall  518  extends upward from panel  510  and has top rim  520  and base  522 . Base  522  is attached to panel  510  proximal to aperture  516 . Thus, cylindrical wall  518  provides a pathway  524  extending from top rim  520  to base  522  that provides egress between first zone  506  and second zone  508 . As described further below, this pathway  524  also helps to house a portion of shutter  818  as well as a portion of the moveable support member  526  which is used to raise and lower the dispense assembly  554  to desired positions. In the preferred embodiment shown, moveable support member  526  and shutter  818  are co-axially nested within this pathway  524 . 
     Moveable support member  526  includes inner wall  528  having top rim  530  and bottom rim  532 . Outer wall  534  is generally concentric with inner wall  528  and extends from top rim  536  to bottom rim  538 . Annular plate  540  couples top rim  530  of inner wall  528  to top rim  536  of outer wall  534 , thus forming an annular chamber  542  between walls  528  and  534 . Outer annular flange  546  extends outward from generally the bottom rim of outer wall  534 , and inner annular flange  548  extends inward generally from bottom rim  532  of inner wall  528 . The annular flanges  546  and  548  help to stiffen moveable support member  526 . Annular flange  548  also provides a convenient surface for mounting dispense assembly  554  to the lower end of moveable support member  526  via mounting holes  549 . Actuating mechanisms (not shown) that cause moveable support member  526  to move through a range of motion in the z-axis  527  may be conveniently coupled to outer annular flange  546 . 
     Inner wall  528  of moveable support member  526  helps to define a conduit  544  that is open from rim  530  to bottom rim  532 . This conduit  544  provides a convenient, protected pathway for leading plumbing and other componentry from first zone  506  to the dispense assembly  554  mounted at the lower end of moveable support member  526 . 
     Moveable support member  526  is moveable in a z-axis  527  relative to the workpiece  12 . Because dispense assembly  554  is mounted to the lower end of moveable support member  526 , movement of moveable support member  526  along the z-axis  527  raises and lowers dispense assembly  554  relative to workpiece  12  as well. 
     Moveable support member  526  is positioned so that inner wall  528  is housed inside pathway  524 . Outer wall  534 , on the other hand, is outside of pathway  524  so that wall  518  remains nested inside annular chamber  542 . There are small, annular gaps between walls  518 ,  528 , and  534  so that these walls do not touch during z-axis movement of moveable support member  526 . These gaps reduce the risk of contamination from debris that might otherwise be generated from contacting surfaces during the course of a treatment. During the course of a treatment, it also may be desirable to maintain the first zone  506  at a slight negative pressure relative to second zone  508 . This would help prevent contamination from passing from first zone  506  through the annular gaps between the ceiling plate  504  and the moveable support member  526  down into the processing chamber  503  area of second zone  508 . As another feature that helps minimize contamination from first zone  506  from compromising the environment within second zone  508 , outer wall  534  of moveable support member  526  also functions in part as a baffle to help block direct access from first zone  506  into the annular gap between inner wall  528  and center wall  518 . The manner in which center wall  518  is nested inside annular chambers  542  and  836  also helps to provide a labyrinth seal between center wall  518  and moveable support member  526  and shutter  818  to further protect the integrity of the environment within second zone  508 . 
     Dispense assembly  554  is mounted to the lower end of moveable support member  526  and generally includes one or more independent mechanisms for dispensing treatment materials into the processing chamber  503 . For instance, the illustrative embodiment of dispense assembly  554  includes at least one, preferably at least two, and more preferably at least three different kinds of dispensing capabilities. As one capability, these mechanisms include one or more dispensing structures that allow assembly  554  to spray one or more treatment fluids downward toward workpiece  12 . In preferred embodiments, this capability is provided by a dispensing structure such as spray nozzle/barrier structure  556  that integrally incorporates independent first and second spray bar functionalities. These independent spraying functionalities allow two independent treatment materials to be sprayed onto workpiece  12  at the same time. Of course, other embodiments may include only a single spray system or three or more spray systems, as desired. 
     Additionally with respect to this particular embodiment, the generally annular body  558  of the spray nozzle/barrier structure  556  functions in one respect as a lid over processing chamber  503  in order to help provide a protected environment for workpiece treatment. However, the generally annular body  558  preferably does not seal processing chamber  503 , but rather comes into close proximity with baffle members  174 ,  218 , and  262  to produce a high restriction to air flow. When tool  10  is placed into a wafer transfer configuration (described further below), the generally annular body  558  and baffle members  174 ,  218 , and  262  are separated by movement of one or more of these components to allow workpiece  12  to be placed into and taken from processing chamber  503 . 
     In more detail, spray nozzle/barrier structure  556  includes an annular body  558  having a lower surface  560 , top surface  562 , inner periphery  564  defining a generally central aperture  575 , and outer periphery  566 . The inner periphery  564  is rounded to help promote smooth gas flow through central aperture  575 . Annular lip  568  extends generally radially outward from outer periphery  566  preferably in a manner so that lip  568  is generally aligned with top surface  562 . Lip  568  and outer periphery  566  form a annular gap  572 . Via z-axis movement of moveable support member  526  to which annular body  558  is mounted, annular body  558  may be positioned so that the ends  182 ,  226 , and/or  270  of one or more of baffle members  174 ,  218  and/or  262  may fit into annular gap  572 . Preferably, a small gap is maintained in annular gap  572  to avoid contact between baffles and annular body  558 . This helps to prevent flow of materials from headspace  502  into the process chamber  503 . Threaded bores  574  facilitate mounting annular body  558 , and hence dispense assembly  554 , to the inner annular flange  548  of moveable support member  526  using screws  846 , or the like, fitted through mounting holes  549 . 
     Preferably, at least lower surface  560  of annular body  558  is canted downward in a radially outward direction relative to workpiece  12  to establish a tapering flow channel  576  between workpiece  12  and annular body  558 . The canted surface  560  can have a variety of geometries. For instance, its geometry can be one or more of conical, parabolic, polynomial, or the like. For purposes of illustration, annular body  558  has a hollow, frustroconical geometry that is truncated at inner periphery  564  so as to provide generally central aperture  575 . The resultant tapering flow channel helps to promote radial flow outward from center of workpiece  12  while minimizing recirculation zones. The taper also helps to smoothly converge and increase the velocity of flowing fluids approaching the outer edge of the workpiece  12 . This helps to reduce liquid splash effects. The angle of lower surface  560  also helps liquid to drain from or drip off of the outer periphery  566  of annular body  558  rather than drain or drip straight down onto the underlying workpiece  12 . 
     Arm structure  578  of spray nozzle/barrier structure  556  extends generally across central aperture  575  and is coupled to inner periphery  564  of annular body  558  at junctures  580  and  582 . Arm structure  578  includes first and second sub-arm portions  584  and  586 . Arm structure  578  includes aperture  589  for mounting central dispense nozzle member  754 . In the preferred embodiment shown, first sub-arm portion  584  is generally aligned with an adjacent portion  590  of annular body  558 , while second sub-arm portion  586  is generally aligned with an adjacent portion  592  of annular body  558 . In particular, the bottom surfaces  598  and  608  of sub-arms  584  and  586  are aligned with lower surface  560  of annular body  558 . Thus, sub-arms  584  and  586  generally meet at an oblique angle. Arm structure  578  subdivides central aperture  575  into first and second aperture portions  594  and  596 . These aperture portions  594  and  596  may function as air intake ports with respect to processing chamber  503  during a treatment. The edges of the adjacent arm structure  578  are desirably rounded to promote smooth, uniform flow through these intake ports. 
     A first generally triangular groove  600  is formed on the underside of spray nozzle/barrier structure  556 . This groove  600  spans at least a portion of a first radius of spray nozzle/barrier structure  556  that extends along portions of first sub-arm portion  584  and the adjacent portion  590  of annular body  558 . This groove  600  includes an apex region  602  extending along the length of groove  600  and adjacent faces  604  and  606 . In a similar fashion, a second generally triangular groove  610  is formed on the underside of spray nozzle/barrier structure  556 . This groove  610  spans at least a portion of a second radius of spray nozzle/barrier structure  556  that extends along portions of second sub-arm portion  586  and the adjacent portion  592  of annular body  558 . Like groove  600 , this groove  610  includes an apex region (not shown) extending along the length of groove  610  and adjacent faces (not shown). 
     The grooves  600  and  610  independently include nozzle features that allow separate streams of treatment materials to be dispensed from one or more respective nozzles or nozzle arrays (described further below) incorporated into the grooves. These nozzles generally dispense treatment material(s) downward toward workpiece  12 , with the nozzle(s) associated with each groove providing coverage with respect to a respective radius of the workpiece  12  for excellent cleaning efficiency. In the preferred embodiment as shown, the grooves  600  and  610  span first and second radii of spray nozzle/barrier structure  556  and are generally opposed with respect to each other. Thus, together, the two grooves substantially span the full diameter of the workpiece  12 . 
     Spray nozzle/barrier structure  556  includes several features in order to incorporate a first, independent spray bar capability into sub-arm portion  584  and the adjacent portion  590  of annular body  558 . These features generally include fluid inlet member  622  having threaded base  624  and flare coupling  626 . A supply tube  854  is fluidly coupled to flare coupling  626  and held in place via flare nut  856  that threadably engages threaded base  624 . Conduit  628  extends from inlet port  630  to flow channel  632  extending generally radially outward through sub-arm portion  584  and a portion of the adjacent portion  590  of annular body  558 . Branch conduits  636  extend from flow channel  632  outward to an array of respective nozzles  638  distributed along apex region  602 . Preferably, the array of nozzles  638  is linear, although other array patterns may be used if desired. It is also preferred that the array of nozzles  638  spans at least a portion and more preferably at least substantially all of a radius of the underlying workpiece  12 . 
     In use, material to be dispensed via nozzles  638  is fed through supply tube  854  into inlet port  630 . From inlet port  630 , the material flows through conduit  628  and then through flow channel  632 . From flow channel  632 , the material is distributed among the branch conduits  636  leading to nozzles  638 , and then is dispensed from the array of nozzles  638 . 
     Sub-arm portion  584  further incorporates fluid inlet member  642  having threaded base  644  and flare coupling  646 . A supply tube  850  is fluidly coupled to flare coupling  646  and held in pace via flare nut  852  that threadably engages threaded base  644 . An inlet conduit  648  extends from inlet port  650  to bifurcation  652 , where the flow channel then splits into conduits  654  and  656 . Conduits  654  and  656  extend from bifurcation  652  to respective flow channels  658  and  660 . Each of flow channels  658  and  660  extend generally radially outward through sub-arm portion  584  and the adjacent portion  590  of annular body  558 . A plurality of branch conduits (not shown) extend from flow channel  658  outward to an array of respective nozzles  664  distributed along face  604  of groove  600 , while branch conduits (not shown) extend from flow channel  660  outward to an array of respective nozzles  665  distributed along face  606  of groove  600 . Preferably, each of the arrays of nozzles  664  and  665  is linear and parallel to each other as well as to the array of nozzles  638 , although other array patterns may be used if desired. It is also preferred that the arrays of nozzles  664  and  665  span at least a portion and more preferably at least substantially all of a radius of the underlying workpiece  12 . 
     Material to be dispensed via nozzles  664  and  665  is fed through supply tube  850  into inlet port  650 . From inlet port  650 , the material flows through conduit  648 . At bifurcation, the flow is distributed between conduits  654  and  656 . The respective flows then flow through channels  658  and  660 . From flow channels  658  and  660 , the respective flows of material are distributed among the branch conduits (not shown) and are then dispensed from the arrays of nozzles  664  and  665 . 
     Conduit  628 , flow channel  632 , and branch conduits  636  are conveniently formed using any desired boring techniques. For instance, flow channels  632 ,  658 , and  660  may be conveniently formed by boring corresponding holes in a direction from the outer periphery  566  of annular body  558  radially inward. After boring the holes to provide flow channels  632 ,  658 , and  660 , plugs  640  may be inserted to seal the ends of the resultant flow channels  632 ,  658 , and  660 . 
     The nozzles  638 ,  664 , and  665  generally dispense fluid streams in a converging fashion so that the dispensed streams atomizingly collide with each other. Liquids, gases, or combinations of these may be dispensed using spray bar system  620 . In one representative mode of operation a liquid material is fed through supply tube  850  and consequently dispensed through nozzles  664  and  665 , while a gaseous material is fed through supply tube  854  and consequently dispensed through nozzles  638 . The respective feeds can be supplied separately or together. When fed together, the dispensed gas stream will help to more energetically atomize the dispensed liquid streams. 
     The spacing, dispense trajectory with respect to the surface of workpiece  12 , orifice size of the nozzles  638 ,  664 , and  665 , and the like may be varied to adjust the spray characteristics of the dispensed streams. For instance, to help create a more uniform spray across the radius of workpiece  12 , the spacing of the nozzle orifices and nozzle orifice sizes may be varied. 
     Additional, independent spray bar functionality may also be incorporated into spray nozzle/barrier structure  556 . As shown, this additional spray functionality is generally identical to that of the first spray bar functionality already described, except for being integrated into second sub-arm portion  586  and the adjacent portion  592  of annular body and extending along a second radius of spray nozzle/barrier structure  556 . The features providing this second spray bar functionality include first fluid inlet member  668  having threaded base  670  and flare coupling  672 , and second fluid inlet member  674  having threaded base  676  and flare coupling  678 . A supply tube  862  is fluidly coupled to flare coupling  672  and held in place by flare nut  864  that threadably engages threaded base  670 . Materials fed through supply tube  862  are dispensed through an array of nozzles (not shown) along an apex of grove  610  that are similar to the array of nozzles  638  along apex  602 . These materials are conveyed through conduits (not shown) that are similar to conduit  628 , flow channel  632 , and branch conduits  636  of first integrated spray bar system  620 . Another supply tube  858  is fluidly coupled to flare coupling  678  and held in place by flare nut  860  that threadably engages threaded base  676 . Materials fed through supply tube  858  are dispensed through arrays of nozzles (not shown) on faces of groove  610  that are similar to arrays of nozzles  664  and  665  on faces  604  and  606 . These materials are conveyed through conduits (not shown) that are similar to inlet conduit  648 , bifurcation  652 , conduits  654  and  656 , flow channels  658  and  660 , and branch conduits (not shown) used in first integrated spray bar system  620 . 
     At least the lower surface  560  of annular body  558  may be hydrophilic or hydrophobic, as desired, depending upon the nature of the treatment(s) that might be carried out using tool  10 . More preferably, the entirety of spray nozzle/barrier structure  556  may be formed from one or more materials having the desired hydrophobic or hydrophilic character. 
     In addition to spraying capabilities, dispense assembly  554  further incorporates dispensing capabilities to dispense one or more treatment fluids generally onto the center of the underlying workpiece  12 . The treatment fluids may be dispensed serially, simultaneously, in overlapping fashion, and/or the like. In preferred embodiments, this capability is provided by a dispensing structure such as central dispense member  754 . For purposes of illustration, central dispense member  754  as shown includes two independent nozzles allowing two different treatment materials to be dispensed onto workpiece  12  at the same time. Of course, other embodiments may include only a single dispensing nozzle or three or more nozzles, as desired. 
     In more detail, central dispense member  754  generally includes body  756  having top  758 , sidewall  760 , and bottom  762 . First and second flare couplings  764  and  766  project from top  758 . First and second rims  768  and  770  project from bottom  762 . A first through conduit  772  extends from first inlet port  774  to first outlet port  776 , while a second through conduit  778  extends from second inlet port  780  to second outlet port  782 . 
     A pin  786  having a threaded bore  788  is housed in conduit  790  extending across body  756 . Pin  786  is inserted into body  756  so that threaded bore  788  is generally aligned with conduit  791 . Mounting screw  793  engages threaded bore  788  and is housed within conduit  791  to help mount central dispense member  754  to dispense assembly  554 . A pair of reliefs  792  and  794  are formed in body  756  to prevent sprayed treatment fluids from impinging on central dispense member  754 . 
     Supply tubes  866  and  868  are coupled to flare couplings  764  and  766  using retainer/spacer clamp  796 . In use, material to be dispensed from central dispense member  754  is fed through one or both of supply tubes  866  and  868  and into one or both of inlet ports  774  and  780 , as the case may be. From inlet ports  774  and/or  780 , the material flows through conduits  772  and/or  778 . From conduits  772  and/or  778 , the material is dispensed from the outlet ports  776  and/or  782  which constitute a pair of nozzles, towards the center of workpiece  12 . Outlet ports  776  and/or  782  can also be angled to help provide fuller coverage of the treatment fluids on the center of workpiece  12 . 
     In addition to spraying and central dispense capabilities, dispense assembly  554  further incorporates still yet further dispensing capabilities to dispense one or more treatment fluids showerhead-style generally downward toward workpiece  12 . This approach is especially useful for dispensing uniform flows of one or more gases and/or vapors into processing chamber  503 . In preferred embodiments, this capability is provided by a dispensing structure such as showerhead dispense member  680 . For purposes of illustration, showerhead dispense member  680  is fed by two supply feeds, which may be the same or independent, thus allowing two different treatment materials to be dispensed into processing chamber  503  at the same time. Of course, other embodiments may include only a single supply feed or three or more feeds, as desired. 
     In more detail, showerhead dispense member  680  generally includes base  682  and cover  734 . Base  682  includes generally circular floor  684  and recessed subfloor  686 . Walls  688  interconnect floor  684  and subfloor  686 . Subfloor  686  includes several aperture features that allow plumbing features to be conveniently and compactly led to spray nozzle/barrier structure  556  and central dispense nozzle member  754 . In particular, apertures  690 ,  696 ,  702 , and  708  fit over fluid inlet members  622 ,  642 ,  668 , and  674 , respectively. Flare nuts  852 ,  856 ,  864 , and  860 , seat against shoulders  700 ,  694 ,  706 , and  712 , respectively, when mounting supply tubes  850 ,  854 ,  862 , and  858  to their respective flare couplings  646 ,  626 ,  672 , and  678 . Optionally, a jam nut can be used to seat against shoulders  694 ,  700 ,  706  and  712  so flare nut does not have to perform dual functions. Similarly, apertures  714  and  716  provide access for coupling supply tubes  866  and  868  to their respective flare couplings  764  and  766  on central dispense nozzle member  754 . 
     Aperture  718  facilitates mounting of central dispense member  754  within aperture  589  and to the underside of subfloor  686  using retainer/spacer clamp  796  and screw  793 . Clamp  796  includes body  798  having sidewall  800 , top  802 , and bottom  804 . First and second conduits  806  and  808  house and help maintain the alignment of supply tubes  866  and  868  that are coupled to central dispense member  754 . Conduit  810  houses screw  793  used to clamp central dispense member  754  in position. Body  798  is relieved on opposing sides so that clamp  796  nests between flare nuts  856  and  864 . 
     Floor  684  of base  682  includes first region  720  and second region  725  positioned on opposing sides of subfloor  686 . First region  720  includes an array of nozzles  722 , while second region  725  includes a second array of nozzles  728 . 
     Cover  734  generally includes raised central panel  736  stiffened by annular rim  738  and beams  739 . First and second chambers  740  and  741  are formed between cover  734  and base  682 . First chamber  740  is generally between cover  734  and nozzles  722 , while second chamber  741  is generally between cover  734  and nozzles  728 . As illustrated, first and second chambers  740  and  741  are isolated from each other, but have a common supply source. If desired, independent supply sources may be used. Fluid inlet members  742  project upward from central panel  736 . Fluid inlet members  742  include threaded bases  744  and flare couplings  746 . Supply tubes  747  are fluidly coupled to flare couplings  746  and held in place via flare nuts  748  that threadably engage threaded bases  744 . Conduits  749  extend from inlet ports  750  to outlet ports  751 , where conduits  749  open into chambers  740  and  741 . 
     Mounting holes  730  on outer periphery  732  of base  682  and mounting holes  752  on cover  734  facilitate mounting showerhead dispense member  680  to annular body  558  using screws  846 . Standoffs  844  help to maintain the desired positioning of showerhead dispense member  680 . Showerhead dispense member  680  is mounted to spray nozzle/barrier structure  556  in a manner so that nozzles  722  and  728  generally overlie aperture sub-sections  594  and  596 . 
     In use, one or more treatment fluids, especially one or more flows of gas(es), are supplied to showerhead dispense member  680  via one or both of supply tubes  747 . The treatment fluids supplied to each tube  747  may be the same or different. The treatment fluids are introduced into chambers  740  and  741  via conduits  749 . The pressure of the treatment fluid(s) within chambers  740  and  741  is generally equalized so that the flow through the nozzles  722  and  728  is uniform. Desirably, the pressure differential of the fluid(s) within chambers  740  and  741  upstream from the showerhead nozzles is desirably less than pressure drop through the nozzles  722  and  728  themselves in accordance with conventional practices to promote such uniform flow. When dispensed through the nozzles  722  and  728 , the dispensed fluid(s) generally flow towards workpiece  12  through aperture sub-sections  594  and  596 . An exhaust may be pulled through one or more of plenums  29 ,  30 , or  31  to facilitate this flow. 
     Shutter  818  is independently moveable in the z-axis  527  relative to the workpiece  12  through a range of motion that includes the generally fully open position as shown in  FIGS. 3 and 6  and the generally fully closed position shown in  FIG. 2 . Desirably, shutter  818  can be positioned in intermediate locations between these two extremes in which shutter  818  is partially opened/closed. In  FIG. 2  in which shutter  818  is in a closed position, moveable support member  526  is lowered into a treatment position at which baffle members  174 ,  218 , and  262  are positioned within annular gap  572  of annular body  558 . This helps to protect the integrity of the environment within process chamber  503 . In the meantime, shutter  818  is raised so that its top portion is nested within annular chamber  542  with annular plate  832  being positioned adjacent to annular plate  540 . A small gap, though, preferably is maintained between annular plates  832  and  540  to prevent contact that might otherwise generate undesired contamination. With the shutter  818  raised and open in this fashion, one or more gases and/or vapors in headspace  502  are free to be drawn into processing chamber  503  through air intake vents formed by aperture sub-sections  594  and  596 . In short,  FIG. 2  shows one embodiment of an illustrative configuration of tool  10  useful to carry out treatment(s) with respect to workpiece  12 . 
     In  FIG. 6 , moveable support member  526  (and hence dispense assembly  554 ) is raised away from baffle members  174 ,  218 , and  262  to allow workpiece  12  to be transferred to and from its position on supporting chuck  94  via resultant gap  874 . In short,  FIG. 6  shows one embodiment of an illustrative configuration of tool  10  useful to accomplish workpiece transfer to and from tool  10 . 
       FIG. 2  shows an illustrative configuration of tool  10  in which shutter  818  is in a closed position. The tool configuration of  FIG. 2  is similar to that of  FIG. 3  except that now shutter  818  is lowered relative to moveable support member  526  so that bottom rim  824  is positioned in close proximity to the top surface  562  of annular body  558 . Desirably, a small gap is maintained so that bottom rim  824  does not actually contact top surface  562 . In this configuration, shutter  818  helps to choke the air intake into processing chamber  503  from the volume of headspace  502  external to shutter  818 , while also helping to contain one or more gases and/or vapors introduced to processing chamber  503  via dispense assembly  554 . For instance, the closed shutter  818  facilitates containing a “fog” of IPA-enriched gas/vapor mixture that might be dispensed toward workpiece  12  via showerhead dispense member  680 . As another example, the closed shutter  818  also could help to contain fluids used to wash the underside of spray nozzle/barrier structure  556 . A suitable negative pressure maintained in headspace  502  relative to processing chamber  503  can help to prevent contamination from entering process chamber  503 . 
     In more detail, shutter  818  includes inner wall  820  having top rim  822  and bottom rim  824 . Outer wall  826  is generally concentric with inner wall  820  and extends from top rim  828  to bottom rim  830 . Annular plate  832  couples top rim  822  of inner wall  820  to top rim  828  of outer wall  826 , thus forming an annular chamber  836  between walls  820  and  826 . Outer annular flange  838  extends outward from generally the bottom rim  830  of outer wall  826  to help stiffen shutter  818 . Annular flange  838  also provides a convenient surface for mounting actuating structures (not shown) that help to move shutter  818  through a range of motion in a z-axis  527  relative to the surface of workpiece  12 . 
     Inner wall  820  of shutter  818  helps to define a conduit  834  that is open from top rim  822  to bottom rim  824 . The inner wall  528  of moveable support member  526  is housed inside this conduit  834 . A small annular gap separates inner wall  528  from inner wall  820  so that the parts do not contact each other when one or both are moved in the z-axis  527 . 
     Shutter  818  is positioned so that outer wall  826  is outside of pathway  524  so that wall  518  remains nested inside annular chamber  836 . In turn, the top part of shutter  818  is nested inside of annular chamber  542  of moveable support member  526 . Preferably, there are small, annular gaps between walls  528 ,  820 ,  518 ,  826 , and  534  so that these walls do not touch during z-axis movements of moveable support member  526  as any contact between the wall surfaces could generate contamination. 
     Other embodiments of this invention will be apparent to those skilled in the art upon consideration of this specification or from practice of the invention disclosed herein. Various omissions, modifications, and changes to the principles and embodiments described herein may be made by one skilled in the art without departing from the true scope and spirit of the invention which is indicated by the following claims.