Abstract:
An apparatus for processing wafer-shaped articles comprises a vacuum transfer module and an atmospheric transfer module. A first airlock interconnects the vacuum transfer module and the atmospheric transfer module. An atmospheric process module is connected to the atmospheric transfer module. A gas supply system is configured to supply gas separately and at different controlled flows to each of the atmospheric transfer module, the first airlock and the atmospheric process module, so as to cause: (i) a flow of gas from the first airlock to the atmospheric transfer module when the first airlock and the atmospheric transfer module are open to one another, and (ii) a flow of gas from the atmospheric transfer module to the atmospheric process module when the atmospheric transfer module and the atmospheric process module are open to one another.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to a system for processing wafer-shaped articles in which wet and dry process modules are integrated. 
         [0003]    2. Description of Related Art 
         [0004]    Processing of semiconductor wafers is performed using various process modules. Some process modules, such as those for plasma etching, are conducted in a vacuum environment and are considered to involve “dry” processes. Other process modules utilize various processing liquids and are conducted in an ambient pressure environment, for example wet etching and/or cleaning, and are considered “wet” processes. 
         [0005]    U.S. Patent Pub. No. 2008/0057221 describes a controlled ambient system for interface engineering, in which a lab-ambient environment and a controlled ambient environment are combined. 
         [0006]    In practice, however, it has seldom been efficient to combine wet and dry process modules, because the wafer throughput for these types of modules differs considerably. 
         [0007]    Thus, the wet and dry process modules are conventionally operated independently of one another. The wait times for wafers to be processed in one type of module, after having been processed in the other type of module, can be significant. For example, in a semiconductor manufacturing facility, it is not unusual for a wafer to have a wait time of a few hours or more after undergoing plasma etching, before the wafer can be rinsed in a wet process module. 
         [0008]    The present inventors have discovered that wafers awaiting their turn for wet processing can undergo slow-rate reactions on the device structures formed on the wafers, as a result of reactive etch residues such as halogens that remain on the wafer surface. This has provided an impetus to develop improved systems that integrate wet and dry process modules, to greatly reduce the wait times between carrying out the wet and dry processing of wafers. 
       SUMMARY OF THE INVENTION 
       [0009]    Thus, in one aspect, the present invention relates to an apparatus for processing wafer-shaped articles, comprising a vacuum transfer module and an atmospheric transfer module. A first airlock interconnects the vacuum transfer module and the atmospheric transfer module. An atmospheric process module is connected to the atmospheric transfer module. A gas supply system is configured to supply gas separately and at different controlled flows to each of the atmospheric transfer module, the first airlock and the atmospheric process module, so as to cause: 
         [0010]    (i) a flow of gas from the first airlock to the atmospheric transfer module when the first airlock and the atmospheric transfer module are open to one another, and 
         [0011]    (ii) a flow of gas from the atmospheric transfer module to the atmospheric process module when the atmospheric transfer module and the atmospheric process module are open to one another. 
         [0012]    In preferred embodiments of the apparatus according to the present invention, the gas supply system comprises a first gas showerhead positioned in an upper region of the first air lock, and configured to dispense gas downwardly within the first airlock. 
         [0013]    In preferred embodiments of the apparatus according to the present invention, the first airlock is configured to accommodate at least one wafer-shaped article of a predetermined diameter, and the first gas showerhead comprises downwardly directed gas discharge openings positioned radially outwardly of a wafer-shaped article of the predetermined diameter when positioned in the first airlock. Preferably the gas discharge openings are located at a distance to the vertical chamber walls of the first airlock less than 5 cm. 
         [0014]    In preferred embodiments of the apparatus according to the present invention, the gas supply system comprises a second gas showerhead positioned in an upper region of the atmospheric transfer module, and configured to dispense gas downwardly within the atmospheric transfer module. 
         [0015]    In preferred embodiments of the apparatus according to the present invention, the atmospheric transfer module is configured to accommodate at least one wafer-shaped article of a predetermined diameter, and the second gas showerhead comprises downwardly directed gas discharge openings positioned radially outwardly of a wafer-shaped article of the predetermined diameter when positioned in the atmospheric transfer module. Preferably the gas discharge openings are located at a distance to the vertical chamber walls of the atmospheric transfer module less than 5 cm. Alternatively, the gas discharge openings are annularly arranged in a ring having a diameter at least  5 mm greater than the diameter of the wafer-shaped article to be treated. 
         [0016]    In preferred embodiments of the apparatus according to the present invention, the gas supply system comprises a first exhaust positioned in a lower region of the atmospheric transfer module, and configured to exhaust at least a part of the gas discharged from the second gas showerhead, away from each of the atmospheric transfer module, the first airlock and the atmospheric process module. 
         [0017]    In preferred embodiments of the apparatus according to the present invention, the atmospheric transfer module is not equipped with a vacuum pump. 
         [0018]    In preferred embodiments of the apparatus according to the present invention, the gas supply system comprises a third gas showerhead positioned in an upper region of the atmospheric process module, and configured to dispense gas downwardly within the atmospheric process module. 
         [0019]    In preferred embodiments of the apparatus according to the present invention, the third gas showerhead is positioned adjacent an inlet opening from the atmospheric transfer module. 
         [0020]    In preferred embodiments of the apparatus according to the present invention, the gas supply system comprises a second exhaust positioned in the atmospheric process module, and configured to exhaust at least a part of the gas discharged from the third gas showerhead, away from each of the atmospheric transfer module and the atmospheric process module. 
         [0021]    In preferred embodiments of the apparatus according to the present invention, the atmospheric process module is not equipped with a vacuum pump. 
         [0022]    In preferred embodiments of the apparatus according to the present invention, the atmospheric process module comprises an outer chamber connected to the atmospheric transfer module, and an inner chamber configured to perform wet processing of a wafer-shaped article. 
         [0023]    In preferred embodiments of the apparatus according to the present invention, the inner chamber comprises a lower bowl and an upper lid, wherein the lower bowl and the upper lid are vertically movable relative to one other. 
         [0024]    In preferred embodiments of the apparatus according to the present invention, the inner chamber accommodates a spin chuck for holding and rotating a wafer-shaped article undergoing processing. 
         [0025]    In preferred embodiments of the apparatus according to the present invention, the spin chuck is a levitating chuck. 
         [0026]    In preferred embodiments of the apparatus according to the present invention, the atmospheric process module comprises an outer chamber connected to the atmospheric transfer module, and an inner chamber configured to perform wet processing of a wafer-shaped article, and the third gas showerhead is positioned within the outer chamber and outside of the inner chamber. 
         [0027]    In preferred embodiments of the apparatus according to the present invention, at least one vacuum process module is attached to the vacuum transfer module independently of the first airlock. 
         [0028]    In preferred embodiments of the apparatus according to the present invention, an equipment front end module is connected to the vacuum transfer module via at least one second airlock, the equipment front end module comprising at least one front-opening unified pod for introducing a wafer-shaped article into the equipment front end module and for removing a wafer-shaped article therefrom. 
         [0029]    In preferred embodiments of the apparatus according to the present invention, a wafer-shaped article may be introduced into and removed from the atmospheric process module only by passing through the atmospheric transfer module, the first airlock and the vacuum transfer module. 
         [0030]    In preferred embodiments of the apparatus according to the present invention, a heater is positioned in at least one of the atmospheric transfer module and the first airlock, the heater being configured to evaporate any residual moisture present on a wafer-shaped article being returned from the atmospheric process module to the vacuum transfer module. Such heater could comprise radiation heater such as LED-heating elements. 
         [0031]    In preferred embodiments of the apparatus according to the present invention, the vacuum transfer module comprises a vacuum transfer robot that is operable to transfer a wafer-shaped article from the vacuum transfer module to the first airlock. 
         [0032]    In preferred embodiments of the apparatus according to the present invention, the vacuum transfer module comprises a vacuum transfer robot that is operable to transfer a wafer-shaped article from the at least one second airlock to the vacuum transfer module, and from the vacuum transfer module to the first airlock. 
         [0033]    In preferred embodiments of the apparatus according to the present invention, the atmospheric transfer module comprises an atmospheric transfer robot that is operable to transfer a wafer-shaped article from the first airlock to the atmospheric transfer module, and from the atmospheric transfer module to the atmospheric process module. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0034]    Other objects, features and advantages of the invention will become more apparent after reading the following detailed description of preferred embodiments of the invention, given with reference to the accompanying drawings, in which: 
           [0035]      FIG. 1  is a top plan view of an apparatus comprising integrated wet and dry process modules, according to a first embodiment of the invention; 
           [0036]      FIG. 2  is a schematic sectional view taken along the line II-II of  FIG. 1 ; 
           [0037]      FIG. 3  is a sectional view of a wet processing device suitable for use in the apparatus according to the present invention; and 
           [0038]      FIG. 4  is a top plan view of an apparatus comprising integrated wet and dry process modules, according to a second embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0039]    Referring now to the drawings, the system of  FIG. 1  comprises a series of Front-Opening Unified Pods (FOUPs)  50 , which are the point of entry and exit if wafers to and from the apparatus. An Equipment Front End Module (EFEM)  53 , including an EFEM robot  56 , is provided for transferring wafers from an FOUP  50  to IN airlock  59 , through slot valve  58 . EFEM robot  56  likewise transfers wafers from the OUT airlock  62 , through slot valve  61 , to an FOUP  50 . An optional atmospheric inspection module  65  is connected to EFEM  53  via slot valve  68 . 
         [0040]    IN airlock  59  and OUT airlock  62  are in turn connected to a vacuum transfer module (VTM)  71 , via respective slot valves  60  and  63 . VTM  71  is equipped with VTM robot  74 , which moves a wafer from IN airlock  59  through slot valve  60 , to a selected one of first vacuum process module  80  and second vacuum process module  83 , through a respective slot valve  81  or  84 . Vacuum process modules  80  and  83  are for example process modules for plasma etching. 
         [0041]    Alternatively, VTM robot  74  moves a wafer from IN airlock  59  through slot valve  60 , to a third vacuum process module  122 , through a slot valve  119 . The third vacuum process module  122  is for example a deposition module. 
         [0042]    VTM robot  74  is also configured to move a wafer from the IN airlock  59  through slot valve  60  to either an optional vacuum inspection module  77 , through its associated slot valve  78 , or to pass-through module (PTM)  87 , through its associated slot valve  86 . 
         [0043]    For all of the foregoing transfers, the VTM robot is also configured to move a wafer along the opposite path to OUT airlock  62  through its associated airlock  61 , as well as between any selected one of the vacuum process modules  80 ,  83 ,  122  and the PTM  87 , in either direction. 
         [0044]    PTM  87  is itself an airlock that connects VTM  71  and an atmospheric transfer module (ATM)  92 , via slot valve  86  on the vacuum side and slot valve  89  on the atmospheric side. ATM  92  is equipped with ATM robot  98 , which is configured to transfer a wafer from PTM  87  through slot valve  89  to an atmospheric process module (APM)  101  through slot valve  96 . APM  101  is for example a process module for wet cleaning of a semiconductor wafer. APM  101  in this embodiment comprises an inner chamber  110  that encloses a spin chuck, as will be described in greater detail below. 
         [0045]    ATM robot  98  is also configured to transfer a wafer from PTM  87  through slot valve  89  to an optional atmospheric inspection module  116  through slot valve  113 . 
         [0046]    Turning now to  FIG. 2 , a first pressure p 1  prevails within VTM  71 , as a wafer is transferred by VTM robot  74 . Pass-through module  87  is equipped with an annular gas distributor  88 , which provides inert gas such as nitrogen gas to the PTM  87 . The annular gas distributer  88  preferably has an inner diameter that is greater than the diameter of the wafer that the apparatus is designed to process, such that the gas outlets of distributor  88  are positioned radially outside of a wafer when present in PTM  87 . In this way, gas discharged from the gas distributor  88  will not impinge in a forceful way on the upwardly-facing surface of a wafer when one is present in the PTM  87 . 
         [0047]    The gas flow generated by gas distributor  88  for purging the PTM  87  is designated G 1  in  FIG. 2 . V 1  denotes a vent for evacuating the purging gas from PTM  87 . The gas distributor  88  and vent V 1  are operated such that a pressure p 2  prevails within PTM  87 . After the wafer has stabilized within the conditions prevailing within PTM  87 , the ATM robot  98  fetches the wafer from PTM  87  through slot valve  89  and brings it into the ATM  92 . 
         [0048]    ATM  92  is equipped with its own gas distributor  95  for purging the ATM  92  with inert gas, and a gas collector  94  that receives gas so as to exhaust the ATM  92 . The gas flow generated by gas distributor  95  is designated G 2  in  FIG. 2 , and the exhaust is designated E 1 . The gas distributor  95  and gas collector  94  are controlled such that a pressure p 3  prevails within the ATM  92 . 
         [0049]    ATM robot  98  next transfers the wafer from ATM  92  to the APM  101 , through slot valve  96 . In APM  101 , there is an inner chamber  110  that contains a spin chuck on which the wafer is mounted, as described in greater detail below. The space within APM  101  outside of inner chamber  110  is maintained as a controlled environment at a prevailing pressure p 4 . In particular, a gas distributor  104  is positioned within the outer chamber of APM  101 , adjacent the slot valve  96 , and generates a downward gas flow G 3 . The inner chamber  110  also receives its won gas flow G 4 . Two exhausts are associated with APM  101 , an exhaust E 2  for the inner chamber  110 , and an exhaust E 3  for the outer environment  107 . 
         [0050]    Reference to a vacuum process module herein connotes a module in which the prevailing pressure is less than 10% of atmospheric pressure, preferably 10 torr or less, and more preferably less than 1 torr. Reference to an atmospheric process module herein connotes a module in which the prevailing pressure is in a range of 0.5 to 1.5 bar, and preferably 0.9 to 1.1 bar. 
         [0051]    The flows of inert gas G 1 , G 2 , G 3 , G 4  described above, as well as the vents and exhausts V 1 , E 1 , E 2 , and E 3  are each independently controlled such that the prevailing pressures p 1 -p 4  satisfy the relationship p 1 &gt;p 2 &gt;p 3 &gt;p 4 , irrespective of the direction of transport of a wafer through the apparatus. In this way, there is a gas flow (when the modules are open toward each other) from PTM  87  to ATM  92 , from ATM  92  to the outer chamber environment  107 , and from the outer chamber environment  107  to exhaust E 3 . This enables treating a wafer in a vacuum process module, transferring the wafer for treatment in an atmospheric process module, and then returning the wafer back through the vacuum system, all while excluding oxygen from the vacuum system. 
         [0052]    The ATM  92  of this embodiment differs from conventional atmospheric transfer modules in that preferably no vacuum pumps are used. Instead, the pressure within the ATM  92  is controlled via gas flow G 2  and a scrubbed exhaust El. Furthermore, the ATM  92  of this embodiment is preferably fully sealed, which enables a wafer to be transferred from EFEM  53  to a vacuum process module and then to an atmospheric process module, then returning to a vacuum environment and to EFEM  53 . This sealed environment also helps prevent the wafer from being exposed to oxygen after plasma etching and before liquid cleaning. 
         [0053]    As discussed above, inert gas such as nitrogen is supplied through the disclosed gas distributors, which are in this embodiment annular in shape, of a diameter greater than that of the wafer to be treated, and which are positioned near the top of their respective chamber so as to dispense gas downwardly. Alternatively, the gas distributors could take the form of side-mounted diffusers. 
         [0054]    As the gas is preferably not recirculated, the flow of e.g. nitrogen is limited to about 500 slm. 
         [0055]    Alternatively, one or more of the gas distributors described herein could take the form of a filter fan unit (FFU), with the gas in that case being recirculated. 
         [0056]    The ATM  92  and/or PTM  87  is preferably equipped with a heater (e.g. a radiant heater like a blue LED heating assembly) in order to desorb adsorbed moisture from the wafer (coming from liquid treatment) before it enters into the vacuum system (before it enters the VTM). 
         [0057]    Referring now to  FIG. 3 , an example of an atmospheric process module  101  is shown. This device is generally as described in commonly-owned copending application Pub. No. 2013/0062839, and reference may be had to that application for any structural details not set forth full herein. 
         [0058]    Outer process chamber  101  is preferably made of aluminum coated with PFA (perfluoroalkoxy) resin. The chamber in this embodiment has a main cylindrical wall  10 , a lower part  12  and an upper part  15 . From upper part  15  there extends a narrower cylindrical wall  34 , which is closed by a lid  36 . The wafer is preferably loaded and unloaded into the chamber  101  via a side opening (not shown). 
         [0059]    A rotary chuck  30  is disposed in the upper part of chamber  1 , and surrounded by the cylindrical wall  34 . Rotary chuck  30  rotatably supports a wafer W during use of the apparatus. The rotary chuck  30  incorporates a rotary drive comprising ring gear  38 , which engages and drives a plurality of eccentrically movable gripping members  40  for selectively contacting and releasing the peripheral edge of a wafer W, as will be described in detail below. 
         [0060]    In this embodiment, the rotary chuck  30  is a ring rotor provided adjacent to the interior surface of the cylindrical wall  34 . A stator  32  is provided opposite the ring rotor adjacent the outer surface of the cylindrical wall  34 . The rotor  30  and stator  32  serve as a motor by which the ring rotor  30  (and thereby a supported wafer W) may be rotated and levitated through an active magnetic bearing. For example, the stator  34  can comprise a plurality of electromagnetic coils or windings that may be actively controlled to rotatably drive the rotary chuck  30  through corresponding permanent magnets provided on the rotor. Axial and radial bearing of the rotary chuck  30  may be accomplished also by active control of the stator or by permanent magnets. Thus, the rotary chuck  30  may be levitated and rotatably driven free from mechanical contact. Alternatively, the rotor may be held by a passive bearing where the magnets of the rotor are held by corresponding high-temperature-superconducting magnets (HTS-magnets) that are circumferentially arranged on an outer rotor outside the chamber. With this alternative embodiment each magnet of the ring rotor is pinned to its corresponding HTS-magnet of the outer rotor. Therefore the inner rotor makes the same movement as the outer rotor without being physically connected. 
         [0061]    The lid  36  has a manifold  42  mounted on its exterior, which supplies a medium inlet  44  that traverses the lid  36  and opens into the chamber above the wafer W. It will be noted that the wafer W in this embodiment hangs downwardly from the rotary chuck  30 , supported by the gripping members  60 , such that fluids supplied through inlet  44  would impinge upon the upwardly facing surface of the wafer W. The wafer is preferably loaded onto chuck  30  from below, and thus the inner diameter of chuck  30  may be less than that of wafer W. Moreover, the lid  36  need not be removable. 
         [0062]    In case wafer  30  is a semiconductor wafer, for example of 300 mm or 450 mm diameter, the upwardly facing side of wafer W could be either the device side or the obverse side of the wafer W, which is determined by how the wafer is positioned on the rotary chuck  30 , which in turn is dictated by the particular process being performed within the chamber  1 . 
         [0063]    The apparatus of  FIG. 3  further comprises an interior cover  2 , which is movable relative to the process chamber  1 . Interior cover  2  is shown in  FIG. 3  in its first, or open, position, in which the rotary chuck  30  is in communication with the outer cylindrical wall  10  of chamber  1 . Cover  2  in this embodiment is generally cup-shaped, comprising a base  20  surrounded by an upstanding cylindrical wall  21 . Cover  2  furthermore comprises a hollow shaft  22  supporting the base  20 , and traversing the lower wall  14  of the chamber  101 . 
         [0064]    Hollow shaft  22  is surrounded by a boss  12  formed in the main chamber  101 , and these elements are connected via a dynamic seal that permits the hollow shaft  22  to be displaced relative to the boss  12  while maintaining a gas-tight seal with the chamber  101 . 
         [0065]    At the top of cylindrical wall  21  there is attached an annular deflector member  24 , which carries on its upwardly-facing surface a gasket  26 . Cover  2  preferably comprises a fluid medium inlet  28  traversing the base  20 , so that process fluids and rinsing liquid may be introduced into the chamber onto the downwardly facing surface of wafer W. 
         [0066]    Cover  2  furthermore includes a process liquid discharge opening  23 , which opens into a discharge pipe  25 . Whereas pipe  25  is rigidly mounted to base  20  of cover  2 , it traverses the bottom wall  14  of chamber  1  via a dynamic seal  17  so that the pipe may slide axially relative to the bottom wall  14  while maintaining a gas-tight seal. 
         [0067]    An exhaust opening  16  traverses the wall  10  of chamber  1 , whereas a separate exhaust opening  46  traverses the lid  36  near the inner surface of rotary chuck  30 . Each exhaust opening is connected to suitable exhaust conduits (not shown), which are preferably independently controlled via respective valves and venting devices. 
         [0068]    The position depicted in  FIG. 3  corresponds to loading or unloading of a wafer W. In particular, a wafer W can be loaded onto the rotary chuck  30  either through the lid  36 , or, more preferably, through a side door (not shown) in the chamber wall  10 . However, when the lid  36  is in position and when any side door has been closed, the chamber  101  is gas-tight and able to maintain a defined internal pressure. 
         [0069]    The lower cup  2  is movable vertically relative to outer chamber  101 , until sealing gasket  26  on cover  2  contacts the inside of chamber  101  and gasket  18  on the inside of chamber  101  contacts the deflector  24 , thereby to formed a sealed inner chamber  110  in which processing of the wafer W is performed. 
         [0070]    As described above, the gas flow G 3  is provided into the volume inside chamber  101  and outside of inner chamber  110 , and is exhausted through exhaust E 3 , whereas inlet  46  for example can be utilized to admit the inner gas flow G 4 , which can then be exhausted (E 2 ) for example through conduit  25 . 
         [0071]      FIG. 4  shows an alternative embodiment in which a second atmospheric process module is provided alongside APM  101 . The ATM  128  of this embodiment thus accesses two APMs and also two PTMs, such that one can be used for entry and the other for exit. The embodiment of  FIG. 4  is otherwise as described in connection with  FIGS. 1-3 . 
         [0072]    While the present invention has been described in connection with various preferred embodiments thereof, it is to be understood that those embodiments are provided merely to illustrate the invention, and should not be used as a pretext to limit the scope of protection conferred by the true scope and spirit of the appended claims.