Patent Publication Number: US-2004040583-A1

Title: Workpiece processing system

Description:
[0001] This Application is a Continuation-In-Part of U.S. patent application Ser. No. 09/621,028, filed Jul. 21, 2000 and now pending, which is a Continuation-in-Part and U.S. National Phase of International Patent Application PCT/US99/08516, filed Apr. 16, 1999, which is a Continuation-in-Part of U.S. patent application Ser. No. 09/061,318, filed Apr. 16, 1998, now abandoned, which is a Continuation-in-Part of U.S. patent application Ser. No. 08/853,649, filed May, 9, 1997, now U.S. Pat. No. 6,240,933. This Application is also a Continuation-in-Part of U.S. patent application Ser. No. 10/315,609, filed Dec. 10, 2002, and now pending. This application also claims priority to U.S. Provisional Patent Application 60/486,771, filed Jul. 10, 2003. Priority to these Applications is claimed under 35 U.S.C. 119 and 120. These Applications are incorporated herein by reference. 
    
    
     
       BACKGROUND OF THE INVENTION  
       [0002] The invention relates to surface preparation, cleaning, rinsing and drying of workpieces, such as semiconductor wafers, flat panel displays, glass masks, rigid disk or optical media, thin film heads, or other articles or workpieces formed from a substrate on which microelectronic circuits, data storage elements or layers, or micro-mechanical elements may be formed. These and similar articles are collectively referred to here as a “wafer” or “workpiece”.  
       [0003] The semiconductor manufacturing industry is constantly seeking to improve the processes used to manufacture microelectronic circuits and components, such as the manufacture of integrated circuits from wafers. The objectives of many of these improved processes are decreasing the amount of time required to process a wafer to form the desired integrated circuits; increasing the yield of usable integrated circuits per wafer by, for example, decreasing contamination of the wafer during processing; reducing the number of steps required to create the desired integrated circuits; and reducing the costs of manufacture.  
       [0004] In the processing of wafers, it is often necessary to subject one or both sides of the wafer to a fluid in either liquid, vapor or gaseous form. Such fluids are used to, for example, etch the wafer surface, clean the wafer surface, dry the wafer surface, passivate the wafer surface, deposit films on the wafer surface, etc.  
       [0005] Various systems and methods have been used for carrying out these manufacturing processes. For example, manual or automated wet benches have long been used for various manufacturing process steps. Wet benches typically have a row of immersion tanks, and a mechanism for sequentially immersing a batch a workpieces into each tank. However, these systems have several disadvantages. These disadvantages include relatively large consumption of process chemicals and water, e.g., 30-35 liters for each wet bench tank, with a bath life of for example 2-4 hours. This consumption of process chemicals increases manufacturing costs, which ultimately increases the cost of the final product, such as e.g., computers, cell phones, and virtually all types of consumer, industrial, commercial and military electronic products.  
       [0006] Many chemistries used in processing, such as HF, HCl, H 2 SO 4 , and H 2 O 2 , are toxic, expensive, and/or difficult to handle and dispose of. As a result, complex draining, recycling, and removal systems are often required for effectively handling and disposing of these used processing chemistries. Furthermore, even when proper disposal procedures are followed, there is still a potential for the used processing chemistries to have a negative environmental impact. Accordingly, there is a need for processing machines and methods having less reliance on these types of chemistries.  
       [0007] Reducing consumption of water is also beneficial, especially in areas where clean water is becoming increasingly scarce. Disposing of waste water from manufacturing operations, in environmentally friendly ways, can often be difficult or costly. Accordingly, reducing water consumption in the manufacturing process is important.  
       [0008] Wafers are processed in clean rooms, to reduce potential for contamination resulting in defects in the end products, such as microelectronic or micromechanical devices. Clean rooms are costly and time consuming to build and maintain. Wafer or workpiece processing machines now in use, such as wet benches, often require a large amount of clean room space. This results in higher manufacturing costs and other disadvantages. Accordingly, there is a need for more compact processing machines, which require less clean room space while maintaining or improving on processing speed or throughput.  
       [0009] Overall processing times for large batches of workpieces in existing processing systems are often relatively slow. Wet bench processing can typically take 45 minutes. In some systems, the workpieces may be moved between several processing stations, during a single processing phase or step. This slows total production time. Alternatively, with some processing systems, including spray systems or vapor deposition systems, only a small number of workpieces can be processed at a given time, and/or only a limited number of processing machines or systems can be fit within the clean room. Accordingly, there is a need for workpiece processing systems that are compact but capable of processing large batches of workpieces in a relatively short amount of time.  
       [0010] For certain processing steps, ozone is introduced into the processing chamber. Ozone is typically introduced with water, sometimes containing dilute amounts of chemical. The ozone is then removed from the processing chamber (optionally along with other chemicals, such as acid vapors) and then exhausted to the atmosphere.  
       [0011] However, ozone is a highly chemically reactive gas. In high concentrations, it can become toxic to humans. The exhaust mixture of ozone can therefore be both toxic, and highly corrosive. Consequently, handling the gas exhaust from a processing chamber generally requires special procedures. For example, components such as ducts, etc. generally must be made of PVDF or other plastics which resist corrosion. Leak detectors may also be employed to detect any leaks in the pipes or ducts carrying the exhaust gases from the processing chamber to the outside.  
       [0012] Ozone converters or destructors have been used to convert ozone in an exhaust flow into oxygen. These converters or destructors typically use catalysts, such as maganese dioxide. The catalyst, however, lose efficiency or ability to catalyze, when they become saturated with condensation. It is also important to prevent stray catalyst particles from moving into the processing chamber, where they can cause contamination.  
       [0013] Accordingly, it is a further object of the invention to provide an improved ozone destructor for destroying ozone, by converting ozone into oxygen.  
       SUMMARY OF THE INVENTION  
       [0014] Processing systems or machines, and methods, have now been invented to overcome the disadvantages described above. These new systems and methods provide for rapid and efficient wafer processing, and at a reduced cost. In addition, these systems and methods avoid the need for using large amounts of various costly or toxic chemistries. The invention therefore provides for significant advances in the technology of manufacturing semiconductor wafers and similar workpieces. The invention is directed to a system for processing workpieces preferably in a standalone processing apparatus having vertically stacked modules. The vertically stacked modules advantageously contain the system components used in processing the workpieces.  
       [0015] In a first aspect, a system for processing a workpiece includes a first module including an ozone generator. A second module is attached to the first module and includes a processing chamber for processing a workpiece. The ozone generator provides ozone to the processing chamber. A third module, which includes a system controller, is attached to at least one of the first and second modules. The system is highly compact and requires a minimum amount of floor space in a clean room. This reduces both initial and follow on operating costs, and allows for higher throughput or manufacturing speed, via more systems within the clean room. In comparison to a typical wet bench system which may require 150 square feet of clean room floor space, the present system occupies less than 10 or even less than 8 square feet, while having an increased throughput. Moreover, the present system uses only a small fraction of the volume of process chemistries required by wet bench systems. In addition, the initial cost of the present system is less than wet bench systems.  
       [0016] In another aspect, a rotor in the processing chamber for holding and rotating a plurality of workpieces is rotatable about an axis that is inclined from horizontal. The rotor is preferably configured to hold at least two workpiece-carrying cassettes, with each cassette preferably holding up to 25 workpieces. As a result, processing speeds are increased while use of de-ionized (DI) water per wafer processed, are reduced. In comparison to wet bench processing requiring e.g., 45 minutes, the present system requires only e.g., 15 minutes.  
       [0017] In another aspect, an ozone destructor or converter is connected with the processing chamber. Ozone gas used in processing in the processing chamber is exhausted to the ozone destructor where it is converted to oxygen. This ozone conversion is performed within the system. The potential for release of toxic ozone gas is reduced. The ozone destructor advantageously uses catalyst to convert ozone to oxygen. Saturation of the catalyst with condensation is reduced or avoided by novel design and arrangement of the ozone destructor.  
       [0018] Other features and advantages of the invention will be apparent to persons knowledgeable in this technology, from the following description taken together with the accompanying drawings. While the drawings show a single embodiment of the invention, various changes, modifications and substitutions can of course be made within the scope of the invention. The invention resides as well in sub-combinations of the features described and in the individual components. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0019] In the drawings, wherein the same reference number denotes the same element throughout the several views:  
     [0020]FIG. 1 is a front perspective view of a workpiece processing system according to a preferred embodiment, with various covers removed for purpose of illustration.  
     [0021]FIG. 2 is rear perspective view of the processing system of FIG. 1.  
     [0022]FIG. 3 is a perspective view of a processing chamber assembly according to a preferred embodiment.  
     [0023]FIG. 4 is a perspective view of a rotor that may be used in the processing chamber assembly of FIG. 3.  
     [0024]FIG. 5 is a schematic diagram of a preferred processing method.  
     [0025]FIG. 6 is a schematic diagram of an alternative preferred processing method.  
     [0026]FIG. 7 is an exploded perspective view of the ozone destructor shown in FIGS. 1 and 2.  
     [0027]FIG. 8 is a section view of a preferred ozone destructor as shown in FIGS.  5 - 6 . 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
     [0028] The terms workpiece, wafer, or semiconductor wafer, as used here, mean any flat media, including semiconductor wafers and other substrates or wafers, glass, mask, and memory media, MEMS substrates, or any other workpiece having micro-electronic, micro-mechanical, or micro electro-mechanical devices.  
     [0029] Turning now in detail to the drawings, as shown in FIGS. 1 and 2, a workpiece processing system  10  preferably includes a first module  12 , a second module  14 , and a third module  16 . More or less modules may be included in the processing system  10 , but three modules are preferred. Each module houses a variety of processing system components.  
     [0030] The processing system  10  may be used to process workpieces of various sizes, but is typically configured to process workpieces of one size, such as 200 or 300 mm diameter semiconductor wafers. The area that the processing system  10  occupies on a clean room floor, or the system&#39;s “footprint,” is preferably minimized to increase the amount of space available for additional processing systems and/or other clean room equipment. In the standalone processing system  10 , which uses a modular construction to be as compact as possible, the size of the workpieces to be processed generally dictates the minimum possible size of the system footprint, as well as the minimum height of the system. Thus, with certain limitations, the smaller the size of the workpieces that are processed in the processing system  10 , the smaller the system footprint and height may be.  
     [0031] When processing 200 mm semiconductor wafers, the footprint of the third module  16 , or the bottom module, is preferably 19 to 23 inches wide by 47 to 53 inches long, more preferably 20 to 21 inches wide by 49 to 51 inches long. For processing larger workpieces, such as 300 mm semiconductor wafers, the third module  16  is preferably 24 to 28 inches wide by 47 to 53 inches long, more preferably 26 to 27 inches wide by 49 to 51 inches long. The first and second modules  12 ,  14  preferably have similar cross-sectional areas to the third module  16 , and may be slightly smaller, as illustrated in FIGS. 1 and 2.  
     [0032] When configured for processing 200 mm semiconductor wafers, the first, second, and third modules  12 ,  14 ,  16  preferably have a combined height of 58 to 62 inches, more preferably 60 inches. For processing larger workpieces, such as 300 mm semiconductor wafers, the first, second, and third modules  12 ,  14 ,  16  preferably have a combined height of 62 to 66 inches, more preferably 64 inches. Accordingly, the footprint and height of the standalone workpiece processing system  10  are generally significantly smaller than those of typical existing processing systems. Thus, the processing system  10  is compact, and takes up relatively little space in a clean room environment.  
     [0033] The first module  12  preferably includes a system controller, which includes a control panel and display  18  at the front of the first module  12  for controlling and monitoring operation of the system. The first module  12  also preferably includes a system power supply and any other electrical or electronic devices required for performing the various system operations.  
     [0034] The second module  14  includes a processing chamber assembly  20 , as illustrated in FIGS. 2 and 3. The processing chamber assembly  20  includes a substantially cylindrical processing chamber  22  or bowl that is mounted to the second module  14  via support mounts  23 . The support mounts  23  are preferably attached to support beams or another suitable base structure in the second module  14  via bolts or fasteners.  
     [0035] The second module  14  further includes a door  64  to provide access into the processing chamber  22 . The door  64  preferably forms a seal with a front end  24  of the processing chamber  22 . A window  66  is preferably located in the door  64  for allowing visual inspection into the processing chamber  22 .  
     [0036] The processing chamber  22  may be oriented horizontally but is preferably inclined upwardly at an angle of, for example, 5-30°, and preferably about 10°, so that the front end  24  of the processing chamber  22  is at a higher elevation than the back end  26  of the processing chamber  22 . Examples of such a processing chamber  22  and chamber assembly  20  are described in U.S. Pat. No. 6,418,945, incorporated by reference.  
     [0037] A rotor  40 , as illustrated in FIG. 4, is preferably rotatably supported within the processing chamber  22 . A drive shaft  42  extends from the back of the rotor  40  into a motor  44  located at the back end  26  of the processing chamber  22 . Power cables extending from the system controller in the first module  12  preferably provide electrical power and control to the motor  44  via connectors  46 . The back end  26  of the processing chamber  22  is preferably sealed with a suitable seal assembly  27 .  
     [0038] The rotor  40  preferably incorporates a dual-cassette design including a first or back cassette position  50 , and a second or front cassette position  52 . As a result, the rotor  40  can hold two carriers or cassettes, a first cassette  54 , and a second cassette  56 . Workpieces  55  are held within slots or wafer positions within each cassette  54 ,  56 . Typically, the cassettes hold, for example, up to 25 wafers, although other cassette sizes may be used. The workpieces  55  are spaced apart from each other within the cassette, to allow processing fluids and/or gases to contact all surfaces of the workpieces  55 .  
     [0039] The cassettes are generally standard components available from various manufacturers, although the size, shape, and features of different types of cassettes may vary. The rotor  40  may be adapted to hold a specific cassette (model number) from a specific manufacturer. Thus, the features and dimensions of the rotor  40  are adapted to the specific size, shape, and features of the cassettes selected for use in the processing system  10 . Specific examples of rotors and cassettes that may be used in the processing chamber  22  are described in detail in U.S. Pat. No. 6,418,945.  
     [0040] For ease of design, manufacture, and use, the first cassette  54  is preferably of the same design as the second cassette  56 , so that the first and second cassettes positions  50 ,  52  within the rotor  40  may be the same. Although the invention contemplates any rotor having positions for first and second cassettes, regardless of whether the cassettes are of the same design, using two of the same cassettes: (a) allows the first and second cassette positions  50 ,  52  to be the same; (b) allows the rotor to be generally symmetrical; and (c) makes the loading sequence of the cassettes  54 ,  56  irrelevant.  
     [0041] Depending upon the chemicals to be used in the processing system  10 , the rotor  40  and the processing chamber  22 , as well as other components exposed to the chemicals, may be made of stainless steel, or alternatively the rotor and processing chamber material may be Teflon® (i.e., fluorine containing resins), or another suitable material. In a preferred embodiment, harsh chemicals, such as acids and solvents (e.g., HF, HCl, H 2 SO 4 , and H 2 O 2 ), are not used in the processing system  10 , so that a stainless steel processing chamber  22  and rotor  40  may be used, and so that any negative impact on the environment is substantially minimized.  
     [0042] As illustrated in FIG. 4, spray manifolds  60  for delivering processing fluid and/or rinse water preferably extend substantially along the entire length of the processing chamber  22 . The manifolds  60  have spray nozzles or other openings directed into the processing chamber  22  for spraying liquids or gases into the processing chamber  22 . The spray system in the chamber  22  is preferably designed as described in U.S. patent application Ser. No. 10/199,998, filed Jul. 19, 2002, and incorporated herein by reference. A vent  62  is preferably included to exhaust gases or vapors from the processing chamber  22 , as well as a drain  47  to remove liquids from the processing chamber  22 .  
     [0043] The processing chamber  22  may further include various other components to enhance processing of the workpieces  55 . For example, the processing chamber  22  may include: (a) an anti-static generator to reduce static electricity within the chamber  22 ; (b) one or more heaters to heat the workpieces  55  and/or the processing and or rinsing fluids; (c) an ozone destructor  45  to convert ozone into oxygen.  
     [0044] The third module  16  preferably serves as a process fluid storage compartment. The third module  16  preferably contains an ozone generator  70  in communication with or connecting with the processing chamber  22  for providing ozone gas into the processing chamber  22 . The ozone generator  70  is preferably connected to a gas spray manifold  61  in the processing chamber  22  via one or more ozone delivery lines (not shown). In a preferred embodiment, the ozone generator  70  is a high capacity ozone generator that may generate up to 240 g/cubic meter of ozone, or approximately 90 g/hour of ozone. If needed, separate cooling water lines may be routed to the ozone generator.  
     [0045] A DI water supply is preferably in communication with the processing chamber  22  for supplying DI water into the processing chamber  22 . The DI water may be supplied from a DI water reservoir located in the third module  16 , or may be supplied from an external source via one or more fluid delivery lines or other suitable fluid delivery means. One or more heaters may be located in the third module  16 , or in another suitable location, for heating the DI water before it enters the processing chamber  22 .  
     [0046] The third module  16  may house additional processing fluid supplies, such as an ammonium hydroxide (NH 4 OH) supply, and/or any other suitable processing fluid supplies. Any fluid supplies used in the processing system  10  preferably communicate with the processing chamber  22  via one or more fluid delivery lines. A purge gas and/or drying gas (e.g., N 2  ) and/or clean dry air (CDA) if used, are typically supplied provided to the system from the fab or facility.  
     [0047] The third module  16  may further include pumps, filters, and/or other components for effectively providing the processing fluids and/or gases into the processing chamber  22 . Additionally, the third module  16  may include alarms, sensors, and other monitoring devices to detect processing fluid levels in the processing chamber and to alert an operator when a problem may exist within the processing chamber. One or more of these devices may alternatively be located in the first or second modules  12 ,  14 .  
     [0048] Referring to FIGS. 7 and 8, a preferred ozone destructor  45  has an upper end  151  and a lower end  153 . The exhaust line  52  from the process chamber  22  connects at an inlet  174  at or near the upper end  151  of the ozone destructor  45 . As shown with the arrows E in FIG. 8, exhaust from the process chamber flows down within the ozone destructor  45 , reverses direction, and then flows up through a catalyst  164  and then out of the ozone destructor  45  through an outlet to the system or enclosure exhaust line  63 . The drain line is either valved or trapped to prevent ozone flow to the drain.  
     [0049] While FIG. 8 shows the ozone destructor  45  in a vertically upright position, with exhaust gas flowing vertically up through the catalyst  164 , the ozone destructor  45  may also have a different position or orientation, so long as there is a vertical component to the flow direction through the catalyst.  
     [0050] Referring still to FIG. 8, by having the exhaust gas enter and exit at or adjacent to the top of the ozone destructor  45 , and flow upwardly through the catalyst  164 , the catalyst  164  is better isolated from the chamber exhaust line  52  and the process chambers. Consequently, potential for catalyst particles to move into the chamber exhaust line or process chambers is reduced, as catalyst particles would have to move against both gravity and exhaust flow to move into the chamber exhaust line  52 . As exhaust also flows up through the catalyst, any condensation within the catalyst can run down, via gravity and drain out. This helps to prevent loss of catalytic action due to saturation of the catalyst. Ozone in exhaust flow moving through the catalyst  164  is converted into oxygen, which can then be vented out through the system exhaust  63 .  
     [0051] Referring still to FIGS. 7 and 8, the following additional detailed description relates to a preferred ozone destructor design, without individually describing any single essential elements of the invention. The ozone destructor  45  has an outer container  152  which may be supported on or in an enclosure with a mounting bracket  155 . A lid  166  is supported and attached to a flange  158  of the outer container  152 . An o-ring or seal  156  seals the lid  166  to the outer container  152 . Lid bolts or fasteners  170  secure the lid  166  to the outer container  152 . An inner container or canister  160  contains the catalyst  164 , typically a manganese dioxide-based catalyst suitable for decomposing ozone into oxygen. A perforated plate  162  at the lower end of the canister  160  holds the catalyst  164  (typically beads of solid material) within the canister  160 . The perforated plate  162  has openings allowing exhaust gas to enter at the bottom, with the openings forming canister inlets  165 . A canister collar  163  is attached at the top or upper end of the canister or inner container  160 . Canister mounting bolts  168  attach the canister  160  via the canister collar  163  to the lid  166 . A canister o-ring  172  seals the canister collar  163  against the lid  166 . A lid bushing  176  extends through an opening in the lid and into the canister collar  163 , connecting with the canister outlet  175 , at the top or upper end of the canister  160 . A pipe nipple  178  connects an aspirator  180  with the. canister outlet  175  through the lid bushing  176 . A clean dry air supply line  182  connects to the inlet side of the aspirator  180 . The outlet side of the aspirator  180  connects, directly or indirectly to the system exhaust line  63 . The aspirator  180  may be replaced by an air amplifier. The inlet  174  provides an entry flow path into the ozone destructor  45 , through the lid  166 .  
     [0052] Referring to FIG. 8, the canister or inner container  160  containing the catalyst  164  is preferably suspended within the outer container  152 . As shown in FIG. 7, the outer container  152  and inner container  160  are preferably cylindrical, although other cross section shapes may also be used. Referring to FIG. 8, an annular flow path extends from the inlet  174  down within the ozone destructor  45 , between the outside walls of the inner container  160  and the inside walls of the outer container  152  to the canister inlets  165 . Of course, other types of ozone destructors may also be used, including thermal, UV, and catalytic devices, or other equivalents which can convert, neutralize or destroy ozone.  
     [0053] In use, workpieces  55  are loaded into cassettes  54 ,  56  either manually or via a robot or other automated device. The door  64  on the second module  14  is opened, preferably manually by an operator, to provide access into the processing chamber  22 . The first cassette  54  is lifted and placed into the rotor  40 , as described in U.S. Pat. No. 6,418,945. The first cassette  54  is moved toward the back of the rotor  40  until it can be moved no farther. As the rotor  40  is preferably positioned at an inclined angle, as shown in FIGS. 2 and 3, the first cassette  54  moves down into and is seated into the first cassette position  50  within the rotor  40  with some assistance by gravity.  
     [0054] With the first cassette  54  installed within the rotor  40 , the operator loads the second cassette  56  into the rotor  40 , following the same procedure. The second cassette  56  is moved into the rotor  40  until it contacts the first cassette  50 , such that it can be moved no farther toward the back of the rotor  40 .  
     [0055] The operator then closes the door  64 . A processing sequence can be preprogrammed into the system controller, or can be set up or selected by the operator using the control panel and display  18 . In a typical application, as illustrated in the schematic diagram of FIG. 5, ozone gas is sprayed into the processing chamber  22  via manifolds  60  while the motor  44  spins the rotor  40 . As the rotor  40  begins to rotate, the workpieces  55  are held within their respective cassettes  54 ,  56  by retainer bars or other retaining mechanisms, as described in U.S. Pat. No. 6,418,945.  
     [0056] Heated DI water (provided by a heater  43  in the system or separately supplied) is concurrently sprayed into the processing chamber  22  in order to form a heated liquid boundary layer, through which the ozone gas may diffuse, on the surface of each of the workpieces  55 . The DI water is preferably heated to a temperature of 30 to 110° C., more preferably 40, 50, 60, 70, 80 or 90 to 100° C. The ozone diffuses through the heated boundary layer, which accelerates diffusion-reaction kinetics, to react at the surface of the workpiece, as described in U.S. Pat. No. 6,267,125, and U.S. Pat. No. 6,497,768, incorporated by reference.  
     [0057] In an alternative embodiment, as illustrated in FIG. 6, ammonium hydroxide (NH 4 OH) from a source or tank  49  may be mixed with (or injected via a pump  51 ) into heated DI water before the DI water enters the processing vessel  22 , in order to enhance the cleaning process. The concentration of NH 4 OH in the DI water is preferably very low, on the order of approximately 500-5000:1 or 1000-3000 or about 2000:1 parts DI water to NH 4 OH. The addition of NH 4 OH is particularly effective in photoresist removal applications, as it generally increases the removal rate of photoresist layers. NH 4 OH mixed with heated DI water may also be supplied to the processing chamber as a separate step after first performing the steps of delivering ozone and DI water into the processing chamber  22 . Use of ammonium hydroxide provides improved particle performance, cleaning efficiency of SiN particles, and removal of anti-reflective coatings.  
     [0058] After the cleaning and/or stripping steps are performed, the workpieces  55  are typically rinsed using DI water that is sprayed from the manifolds  60 , and then dried with a drying gas, such as N 2  gas. A purge gas, such as N 2  gas, may be used between the rinsing and drying steps, or between other processing steps, to remove excess fluids from the processing chamber. Exhaust vapors and gases flow out of the chamber through the exhaust port  62  and into the ozone destructor  45 . Ozone in the ozone destructor is converted in oxygen gas which flows out of the system enclosure via an exhaust gas duct  63 , along with other exhaust gases or vapors. The various processing steps may be repeated one or more times to enhance the cleaning or stripping processes, as desired.  
     [0059] Referring to FIG. 8, the exhaust gas moves into the ozone destructor at or near the upper end  151  and moves downwardly, as shown by the arrows E. The exhaust flow E moves to the lower end  153  of the ozone destructor  45 , reverses direction, and flows upwardly through the perforated plate  162  and into the canister  160 . As the exhaust flows through the catalyst  164  within the canister  160 , ozone within the exhaust gas E is converted into oxygen. The aspirator or air amplifier  180  helps to draw exhaust gas flow through the ozone destructor  45 , thereby eliminating any back pressure on the process chamber. Oxygen converted by the catalyst  164 , and any other exhaust gas components, move upwardly through the canister outlet  175 , through the aspirator  180 , and out via the system exhaust line  63 .  
     [0060] If water vapor condenses within the catalyst  164 , the liquid water drains out downwardly through the perforated plate  162  and collects at the lower end  153  of the outer container  152 , where it can be removed by the liquid drain line  184 . Consequently, saturation of the catalyst  164  with condensation is avoided. As the exhaust flow inlet into the ozone destructor  45  is at or near the upper end  151 , the potential for catalyst particles getting into the chamber exhaust line  52  or the process chambers is greatly reduced. Similarly, the potential for condensed liquid to block the exhaust line  52  is reduced or eliminated. Preferably, the components of the ozone destructor  50  coming in contact with exhaust gas are made of stainless steel having a PFA coating to better resist corrosion by chemical vapors in the exhaust flow.  
     [0061] In general, when processing 200 mm workpieces, the processing system  10  has a throughput of approximately 200 workpieces/hour. When processing 300 mm workpieces, the processing system  10  has a throughput of approximately 100 workpieces/hour. The actual throughput will depend on the type of workpiece-processing application that is performed, the number of workpieces processed at one time, and the number of processing steps that are repeated.  
     [0062] The processing system  10  and methods described herein may be used in several different workpiece-processing applications, such as the following: (1) post-ash cleaning; (2) photoresist stripping; (3) organic material cleaning (4) photo reworking/reclaiming; (5) post-etch cleaning; and any other suitable processing applications.  
     [0063] The processing system  10  provides several advantages over existing processing systems. First, the system  10  is extremely compact so it does not take up significant space in a clean room environment. Due to the limited number of components and processing stations required, the processing system  10  is also relatively inexpensive. The processing system  10  uses relatively mild processing chemicals, such as ozone gas and DI water, so there is minimal, if any, negative impact on the environment. Additionally, larger batches of workpieces can be processed in a relatively short amount of time in the processing system  10 .  
     [0064] While embodiments and applications of the present invention have been shown and described, it will be apparent to one skilled in the art that other modifications are possible without departing from the inventive concepts herein. The invention, therefore, is not to be restricted except by the following claims and their equivalents.