Abstract:
A pod opening station moves a wafer-carrying pod horizontally to engage a door of the pod with a pod door receiver. The pod door receiver removes and holds the pod door with no vertical movement thereof. The pod is then moved horizontally in a reverse direction a short distance away from the pod door receiver. Then the pod is moved vertically into alignment with an opening in an interface wall. A wafer handler blade is extended through the opening into the pod. The pod is indexed downwardly to transfer a wafer to the wafer handler blade. The wafer handler blade then retracts to remove the wafer from the pod.

Description:
[0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 09/795,907 filed Feb. 27, 2001, which claims priority from U.S. Provisional Application Serail No. 60/187,133 filed Mar. 6, 2000. Both of these applications (U.S. Ser. Nos. 09/795,907 and 60/187,133) are hereby incorporated by reference herein in their entirety. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention is concerned with semiconductor manufacturing, and is more particularly concerned with an automated method and apparatus adapted to open a sealed wafer-carrying pod and extract wafers therefrom.  
         BACKGROUND OF THE INVENTION  
         [0003]    Conventional semiconductor fabrication systems transport a plurality of wafers in a sealed container or pod, thereby maintaining the wafers in a clean/controlled environment. Thus, conventional processing systems include a plurality of pod opening stations where the sealed pods are opened, and wafers are extracted therefrom and loaded into the processing system. Each pod opening station comprises a pod platform adapted to receive a sealed pod, and a pod door receiver adapted to engage and unlatch a door portion of the pod.  
           [0004]    In operation to open a front opening unified pod (a FOUP), the pod platform receives the pod and moves the pod horizontally toward the pod door receiver. The pod door receiver engages and unlatches the pod door, and moves the pod door horizontally away from the pod platform. The pod door receiver then moves vertically downward to provide clear access to wafers contained in the pod.  
           [0005]    Thereafter, to extract a wafer from the pod, a wafer handler moves vertically to an elevation just below a first wafer contained within the pod, extends, elevates to lift the first wafer off of a supporting mechanism, and retracts carrying the wafer therewith. After placing the wafer within a processing system, the wafer handler elevates to a position just below a second wafer contained within the pod, extends, elevates and retracts carrying the second wafer into the processing system. This sequence repeats for each wafer contained within the pod.  
           [0006]    The wafer handler thus requires a wide vertical opening (e.g., in a clean room wall that separates the wafer handler from the pod) through which wafers may be extracted. The wide opening increases the probability that contaminants may enter the processing system&#39;s clean environment. Further, the multi axis movements required of both the wafer handler and the pod door receiver increase equipment expense and reduce equipment reliability.  
           [0007]    Accordingly, there is a need for an improved pod loading station which requires fewer movements and/or reduces potential contaminants and thus addresses the ever-present demand for reduced cost per unit wafer processed.  
         SUMMARY OF THE INVENTION  
         [0008]    According to a first aspect of the invention, a method of interfacing a wafer carrying pod to a pod opening station includes moving the pod horizontally to engage a door of the pod with a pod door receiver of the pod opening station, and moving the pod vertically to align the pod with an opening of an interface wall of the pod opening station.  
           [0009]    The method may further include moving the pod horizontally away from the pod door receiver after the door of the pod is engaged with the pod door receiver and before the step of moving the pod vertically.  
           [0010]    A wafer handler blade may be extended into the pod after the pod is aligned with the opening in the interface wall and the pod may then be indexed downwardly to transfer a wafer from the pod to the wafer handler blade.  
           [0011]    According to another aspect of the invention, a pod opening station adapted to open and unload a wafer-carrying pod includes an interface wall and a pod platform adjacent the interface wall and adapted to move the pod in a horizontal direction and in a vertical direction. The pod opening station further includes a pod door receiver in the interface wall adjacent the pod platform, the pod door receiver being adapted to remove a door from the pod and to hold the removed door in a fixed position. 
       
    
    
       [0012]    Other objects, features and advantages of the present invention will become more fully apparent from the following detailed description of the preferred embodiments, the appended claims and the accompanying drawings.  
       BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    [0013]FIG. 1 is a partial schematic top plan view of a conventional wafer processing system;  
         [0014]    [0014]FIG. 2 is a schematic side view of a conventional pod opening station;  
         [0015]    FIGS.  3 A- 3 E are cross-sectional views of a pod opening station provided in accordance with the invention, showing sequential steps in a pod opening and wafer unloading operation;  
         [0016]    [0016]FIGS. 4A and 4B are side schematic views of a cover plate for a pod-unloading opening shown in a closed position and an open position, respectively; and  
         [0017]    [0017]FIG. 5 is a front schematic view of the cover plate of FIGS. 4A and 4B. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]    [0018]FIG. 1 is a schematic top plan view, in pertinent part, of a conventional processing system  11  having a factory interface wafer handler  13  for transporting wafers between a plurality of pod opening stations  15  and a processing tool  17 . The exemplary processing system  11  shown in FIG. 1 includes an interface chamber  19  and the processing tool  17  which may comprise a pair of loadlock chambers  23 , a transfer chamber  25  coupled to the loadlock chambers  23 , and a plurality of processing chambers  27  coupled to the transfer chamber  25 .  
         [0019]    An interface wall  29  is positioned between the pod opening stations  15  and the processing system  11  for separating a “white area” clean room  31  from a less clean, “gray area” clean room  33 . The pod opening stations  15  are located in the “white area” clean room  31  and the processing system  11  is located in the less clean, “gray area” clean room  33 . The pod opening stations  15  are positioned adjacent sealable openings  35  in the interface wall  29 . Each pod opening station  15  comprises a pod platform (not shown) adapted to receive a sealed pod and a pod door receiver (not shown) adapted to engage and unlatch a door portion of the sealed pod (not shown) as is known in the art.  
         [0020]    The exemplary interface chamber  19  contains an interface wafer handler  13  mounted to a track T (not shown). The transfer chamber  25  of the processing tool  17  contains a transfer wafer handler  37  adapted to transport a wafer W between the loadlock chambers  23  and the processing chambers  27 .  
         [0021]    In operation, a pod containing a cassette of wafers, is loaded onto the pod opening station  15 . A pod door receiver engages and unlatches the door portion of the pod and removes the door portion so as to allow access to the wafers contained in the pod. The interface wafer handler  13  of the interface chamber  19  then extracts a wafer from the pod and transports the wafer to one of the loadlock chambers  23 . Thereafter, the transfer wafer handler  37  of the processing tool  17  transports the wafer from the loadlock chamber  23  to a processing chamber  27  wherein a processing step is performed on the wafer.  
         [0022]    [0022]FIG. 2 is a schematic side view of a conventional pod opening station  15  which may be employed as the pod opening station  15  of FIG. 1. As previously stated, the pod opening station  15  comprises a pod platform  39  adapted to receive a pod  41  and a pod door receiver  43  adapted to engage and unlatch a door portion  45  of the pod  41  as is known in the art. In FIG. 2, the pod  41  is shown positioned on the pod platform  39 .  
         [0023]    In operation, the pod platform  39  moves along a horizontal plane to receive the pod  41  in a position away from the interface wall  29 . The pod platform  39  then moves the pod  41  into a position adjacent the interface wall  29 , wherein the door portion  45  of the pod  41  engages the pod door receiver  43 . The pod door receiver  43  engages and unlatches the door portion  45  of the pod  41 . The pod door receiver  43  moves the pod door portion  45  horizontally away from the pod platform  39  as indicated by arrow A and then moves the pod door  45  vertically downward as indicated by arrow B, until the opening in the interface wall  29  is cleared.  
         [0024]    Thereafter, to extract a wafer from the pod  41 , the interface wafer handler  13  contained within the processing system  11  moves vertically to an elevation just below a first wafer contained within the pod  41 , then extends to a position beneath the first wafer, elevates to lift the first wafer off of the supporting mechanism (which typically supports the wafers contained within the pod  41  by their edges), and retracts carrying the wafer into the processing system  11 . After placing the wafer within the processing system  11 , the interface wafer handler  13  elevates to a position just below a second wafer contained within the pod  41  and then extends, elevates and retracts carrying the second wafer into the processing system  11 . This sequence is repeated for each wafer contained within the pod  41 .  
         [0025]    The interface wafer handler  13  thus requires a wide vertical opening through which to extract each vertically stacked wafer contained within the pod. The wide opening increases the probability that contaminants may enter the processing system&#39;s  11  clean environment. Further, the multi axis movement required of both the interface wafer handler  13  and the pod door receiver  43  increases equipment expense and reduces equipment reliability.  
         [0026]    Accordingly, the present inventors have provided an improved pod opening station which requires fewer movements and/or may reduce potential contaminants, as described below with reference to FIGS.  3 A-E.  
         [0027]    FIGS.  3 A-E are cross-sectional views of an inventive pod opening station  101 . The inventive pod opening station  101  comprises a pod platform  103  and a pod door receiver  105 . A pod  107  is shown positioned on alignment pins  109  which are connected to the pod platform  103 . A locking mechanism  111  coupled to the pod platform  103  secures the aligned pod  107  in place on the pod platform  103 . The pod platform  103  is translatably mounted (via a horizontal actuator  119 ) to a base plate  115  which supports the pod platform  103 . An enclosure wall  117  encloses the horizontal actuator  119  and a vertical actuator  121  which is positioned below the base plate  115  and coupled thereto so as to selectively raise and lower the base plate  115 . In the exemplary embodiment shown in FIGS.  3 A-E, the horizontal actuator  119  comprises a lead screw  119   a  having a fitting  119   b  movably mounted thereto. The base plate  115  fixedly mounts to the fitting  119   b  and translates therewith along the lead screw  119   a.    
         [0028]    The pod door receiver  105  may define a recess  123  into which a pod door  125  may be received. The recess  123  is defined by a plate  127  and walls  129 . The plate  127  of the recess  123  includes a pod door key actuating mechanism which comprises a key  133  and a pneumatic actuator  135  coupled to the key  133  and adapted to rotate the key  133  so as to unlatch the pod door  125  from the remainder of the pod  107 , Alignment pins  137  are also provided on the plate  127  for aligning the pod door  125  with the pod door receiver  105  such that the pod door receiver key  133  enters a corresponding key hole (not shown) on the pod door  125 .  
         [0029]    An opening  139  in the interface wall  29  is positioned directly above the pod door receiver  105 . A higher pressure may be maintained in the interface chamber  19  than that maintained in the white area clean room  31 , thus deterring air from entering the interface chamber  19  via the opening  139 . In this manner, contaminants may be deterred from migrating into the interface chamber  19 . The interface wafer handler  13  is horizontally aligned with the opening  139  and is adapted to extract wafers  141  (shown in phantom) from the pod  107  and to transport the wafers  141  to the processing system  11  as described below. Alternatively or additionally, an optional cover plate  146  (FIGS.  4 A-B and  5 ) may be designed to occlude and/or seal the opening  139  when the pod  107  is either absent or in an initial, lowered position.  
         [0030]    [0030]FIGS. 4A and 4B are side schematic views showing the cover plate  146  in a closed position and an open position, respectively, and FIG. 5 is a front schematic view of the cover plate  146 . The cover plate  146  may comprise an o-ring  142  having a perimeter larger than the perimeter of the opening  139 . Alternatively the o-ring  142  may be mounted to the interface wall  29  (e.g., in a groove, etc.) as shown. The o-ring  142  is adapted to seal between the outer surface of the interface wall  29  and the cover plate  146 , to thereby seal the opening  139 . Attached to the outer surface of the interface wall  29  (in a position so as not to occlude the opening  139 ) may be a guide mechanism  148  (such as a pair of guide rails). The guide mechanism  148  may be attached to and extend horizontally outward a distance from the outer surface of the interface wall  29 . In this manner the guide mechanism  148  provides a ledge on which the cover plate  146  may rest. The guide mechanism  148  may extend upwardly a distance equal to the maximum upward stroke of the cover plate  146 , as described further below. An extension  144  extends from the outer surface of the cover plate  146  downwardly toward the pod platform  103 . The extension  144  terminates at a position so as to be slightly above the top surface of a pod positioned on the pod platform  103 . In this manner pod  107  may be placed on the pod platform  103  and may move horizontally forward toward the interface to a position wherein the pod  107  is under the extension  144 . Thus when the pod  107  elevates it will contact the extension  144  and thereby open the cover plate  146  as further described below with reference to FIGS.  3 A- 5 .  
         [0031]    The operation of the inventive pod opening station  101  is described with reference to the sequential views of FIGS.  3 A-E, which show the movement of the pod  107 , and with reference to FIGS.  4 A- 5  which are close up views of the cover plate  146 . FIG. 3A shows the pod  107  aligned on the alignment pins  109  of the pod platform  103  which ensure proper positioning of the pod  107  relative to the pod door receiver  105 . The locking mechanism  111  secures the pod  107  to the pod platform  103 . The horizontal actuator  119  then moves the pod platform  103  horizontally toward the recess  123  of the pod door receiver  105 , wherein the pod door  125  engages the pod door receiver  105 , as shown in FIG. 3B.  
         [0032]    The alignment pins  137  on the pod door receiver  105  ensure proper alignment of the pod door  125  such that the key  133  positioned on the pod door receiver  105  engages a lock (not shown) on the pod door  125 . The pneumatic actuator  135  rotates the key  133  to unlock the pod door lock (not shown). Once the pod door is unlocked from the remainder of the pod  107 , the pod platform  103  may move horizontally slightly away from the pod door receiver  105  to a position sufficient for the pod  107  to clear the interface wall  29  as shown in FIG. 3C.  
         [0033]    The vertical actuator  121  moves the base plate  115  and the pod  107  positioned thereon upward, to a position adjacent the opening  139  such that a first wafer contained within the pod  107  is just above the elevation of interface wafer handler  13  as shown in FIG. 3D. As the pod  107  is raised from the position shown in FIG. 3C to the position shown in FIG. 3D, the pod  107  contacts the extension  144  of the cover plate  146  (FIG. 4A). Consequently, the pod  107  raises the cover plate from the position shown in FIG. 4A (shown in phantom in FIG. 5) to the position shown in FIG. 4B (shown in solid lines in FIG. 5), thereby uncovering the opening  139 . Thereafter, to extract the first wafer from the pod  107 , the blade of the interface wafer handler  13  moves horizontally and extends to a position beneath the first wafer. The base plate  115  having the pod  107  positioned thereon then indexes downward via the vertical actuator  121  such that the blade may lift the first wafer off of the support provided within the pod  107 . The blade of the interface wafer handler  13  retracts and carries the first wafer out of the pod  107  and into the processing system  11 . The base plate  115  having the pod  107  positioned thereon then indexes downward such that a second wafer contained within the pod  107  is just above the elevation of the interface wafer handler  13 , as shown in FIG. 3E. The blade of the wafer handler  13  extends to a position beneath the second wafer, the base plate  115  then lowers, the wafer handler retracts and the sequence described above repeats for each wafer contained within the pod.  
         [0034]    Accordingly, the inventive pod opening station  101  may eliminate the vertical movement required of conventional interface wafer handlers  13  and the horizontal movement required of conventional pod door receivers  41  (FIG. 2). With the present invention, the interface wafer handler  13  may employ only horizontal movement, and the pod door receiver  105  may remain stationary. Therefore, the inventive pod opening station  101  may decrease equipment expense and increase equipment reliability.  
         [0035]    Further, the size of the opening  139  in the interface wall  29  may be narrower, particularly as compared to the openings required by conventional pod opening systems. Such a narrow opening reduces the probability that contaminants may enter the processing system  11 &#39;s clean environment.  
         [0036]    The foregoing description discloses only the preferred embodiments of the invention, modifications of the above disclosed apparatus and method which fall within the scope of the invention will be readily apparent to those of ordinary skill in the art. For example, the design of the cover plate and the corresponding guide mechanism may vary. To avoid rubbing between the o-ring and cover plate, the system may be designed such that the pod moves horizontally forward toward the interface wall, has its pod door removed and elevates slightly to contact the cover plate extension. After contacting the extension the pod may move horizontally backward to carry the cover plate slightly away from the interface wall before the cover plate is elevated. Quick release detention pins may be employed to hold the cover plate against the opening.  
         [0037]    The horizontal actuator  119 , the vertical actuator  121 , and the pneumatic actuator  135  may comprise a stepper motor, an electric motor, etc. Also, the specific shapes, sizes and interconnections between components are merely exemplary as is the processing system  11  of FIG. 1. The locking and alignment features are optional, and may vary from those described herein.  
         [0038]    Furthermore, the wafer loading opening  139  may be positioned below the pod door receiver  105  instead of above the pod door receiver, so that the pod  107  is moved vertically downwardly instead of upwardly after the pod door  125  is removed.  
         [0039]    Accordingly, while the present invention has been disclosed in connection with the preferred embodiments thereof, it should be understood that there may be other embodiments which fall within the spirit and scope of the invention, as defined by the following claims.