Abstract:
A substrate container and a bottom plate are connected with a mechanism for adjusting the distance between the container and bottom plate, by, e.g., a threaded connection between two members of the connector mechanism. Also provided are a duck-billed valve for venting the container and a dampener for minimizing damage due to shocks.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS  
       [0001]     This application is a continuation of application Ser. No. 10/982,400 filed Nov. 4, 2005, now U.S. Pat. No. 7,201,276 issued Apr. 10, 2007, which claims the benefit of U.S. Provisional Application No. 60/518,064 filed Nov. 7, 2003. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates to sealable containers with latching systems for confining silicon wafers, flat panels, other substrates and the like for transport storage and processing. More particularly the invention relates to such containers with lower plates for providing engagement and interface with associated equipment.  
       BACKGROUND  
       [0003]     Wafer carriers or pods are utilized for holding, transporting, and storing substrates before, during and after processing. Such substrates are used in the fabrication of semiconductors such as integrated circuits and liquid crystal display panels. In their transformation into the end product, these delicate and highly valuable substrates are subjected to repeated processing, storage, and transportation. Such substrates must be protected from damage from particular contaminants, static discharges, physical damage from breakage, or contamination from vapors or gasses such as those outgassing from materials used in processing.  
         [0004]     Such substrate containers are termed FOUPs, an acronym for front opening unified pods and FOSBs, an acronym for front opening shipping box. Industry standards specify that such substrate containers utilize kinematic couplings comprising three radially oriented grooves on the bottom of the container that interface with three rounded projections arranged in a triangle on the processing equipment. These kinematic couplings provide for the precise orientation of the wafer containers, thereby allowing for precise manipulation of the container and contents, for example robotic removal and insertion of the wafers. Such containers typically will have means for allowing robotic transfer of the containers with contents. Such means may include a robotic flange on the top of the wafer container as well as suitable rails or other features on the bottom of the container to allow the container to be suitably conveyed on conveyors with rollers or suitable carriages. It is apparent that sudden starts and stops, that is jarring of the wafer container with loaded wafers, can cause damage to the wafers. Thus, it is appropriate to provide suitable cushioning for the wafers during transport, including conveyance within a facility. The wafer restraints and exterior packaging conventionally provide such cushioning during transport from facility to facility. It is also desirable to have additional dampening and cushioning for the wafers when the containers are transported by way of conveyors that engage the bottom plate of the FOUP and/or FOSB&#39;s within a facility.  
         [0005]     Such FOUP&#39;s and FOSB&#39;s utilize latching mechanisms in their doors with seals to create a hermetically sealed container. Such containers then need vents and/or purges to prevent deformation of the carrier or unintended leakages due to pressure differentials, for example, changes in barometric pressure. Utilizing such filters in various locations on the pods are known in the art and typically have an aperture in the shell with a suitable fixture and filter secured at the aperture.  
         [0006]     Generally, it is considered desirable by the industry to minimize the number of openings leading into such containers. Prior art containers typically utilize molded-in openings in the shell portion for attachment of such filters or purging features.  
         [0007]     In that the kinematic coupling must be precisely positioned with respect to wafer shells to allow for these precise interactions of processing equipment with the container and wafers, the positioning of the three grooves on the bottom of the wafer container with respect to the shelf location is absolutely critical. In that these wafer containers are conventionally molded of thermal plastics which may warp and distort during the molding process or subsequently, great care must be taken to provide this precise positioning. Known means for attaching the kinematic coupling features to the container portion include direct molding of the grooves in the shell, attachment of a separate plate with the grooves by way of screws, utilization of an interior super structure that includes the wafer shell and a lower plate that has the grooves and that is inserted within the shell portion. It would be desirable to utilize a separately molded plate attachable to the container that has adjustment capability and that is securely attached by more than the minimal near point attachment provided by screws. Such a separate plate can thus easily add additional features such as conveyor interface features, for example rails, coating means, and attachment means for other accessories by using different plate configurations or simply attaching the items to the plate. Also suitable means should ideally be provided for facilitating grounding of the wafer contact areas on the shell through the kinematic coupling to the kinematic coupling protrusions on the equipment or other receiving base upon which the wafer container is seated.  
       SUMMARY OF THE INVENTION  
       [0008]     A front opening substrate carrier having a container portion and a latching door to close the container portion has a separately formed plate that attaches to the bottom of the container portion providing unique attachment means and novel features and advantages. In preferred embodiments the bottom plate has a kinematic coupling groove with contact surfaces formed therein and conveyor rails positioned at the perimeter of said plate. In preferred embodiments the plate may be attached at a plurality of locations on the bottom of the container portion by way of a plurality of large diameter connectors, for example, greater than about one-half inch and less than three inches, extending through cooperating holes on the plate and container portion. Such connections may be made by a unitary snap-in bushing that may be closed or have a bore extending therethrough. Said bore in preferred embodiments may be configured for receiving filter and/or valve cartridges or members. Additionally, such attachment positions may utilize elastomeric bushings or differently configured elastomeric members to provide dampening between the conveyor plate and the shell.  
         [0009]     In other preferred embodiments, the container portion may have a plurality of openings on the bottom that have a first member attached thereto with a threaded end that engages a second member attached to the plate with at least one of the members rotatable to provide precise vertical positioning of the plate with respect to the shell or container portion and thus with respect to the wafer support shell. Said adjustment means may utilize an O-ring or similar friction-providing device to secure the two threaded members in the desired position. Said threaded members may both be formed separately from the container portion and plate, may snap into place, may utilize O-rings for suitable sealing, and may have a bore extending through both members for receiving a filter and/or valve cartridge or members.  
         [0010]     In preferred embodiments, a cartridge may be provided that includes a duck bill purge valve formed of a thermal plastic elastomer with a V or inverted V-shape in one direction and a rectangular shape in a direction taken perpendicular to said first direction. Adding a slit subsequent to the molding of said member may preferably form said duckbill valve. Additionally, the cartridge may have filter members.  
         [0011]     In preferred embodiments elastomeric cushioning members may be positioned at some of the connection points between the container portion and the plate or between all of the connection points between the plate and the container portion thereby providing total isolation of the plate from the container portion by way of the elastomeric dampeners. In other embodiments, the elastomeric dampeners may be positioned to dampen the vibrations caused by conveyance on peripheral rails of the plate while allowing separate rigid fasteners to provide precise and rigid connection of the more inner portions of the conveyor plate, thereby allowing the precise positioning of the kinematic coupling grooves to the wafer shells. 
     
    
     DESCRIPTION OF THE FIGURES  
       [0012]      FIG. 1  is a perspective view of a front opening wafer container tipped on its backside to illustrate the bottom plate, which embodies aspects of the invention herein.  
         [0013]      FIG. 2  is a bottom plan view of a plate attached to the bottom of a wafer container embodying the inventions herein.  
         [0014]      FIG. 3  is a side elevational view of a wafer carrier according to the invention herein.  
         [0015]      FIG. 4  is an exploded perspective view of a container portion, plate, and connectors according to the inventions herein.  
         [0016]      FIG. 5  is a perspective view of the bottom of the wafer container of  FIG. 1  without the plate attached.  
         [0017]      FIG. 6  is a perspective view of the top side of the plate illustrated in  FIG. 1 .  
         [0018]      FIG. 7  is a perspective view of a pronged connector according to aspects of the invention herein.  
         [0019]      FIG. 8  is a cross-sectional view of an apparatus and method to adjust wafer plane using threaded members connecting the container portion with the plate in accordance to the invention herein.  
         [0020]      FIG. 9  is a perspective view of an alternative filter/valve cartridge according to aspects of the invention herein.  
         [0021]      FIG. 10  is a perspective view of an alternative filter/valve cartridge according to aspects of the invention herein.  
         [0022]      FIG. 11  is a cross-sectional view of a duckbill valve in accordance to the invention herein.  
         [0023]      FIG. 12  is an exploded view of the duckbill valve of  FIG. 11 .  
         [0024]      FIG. 13  is a perspective view of an elastomeric dampener according to aspects of the invention herein. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0025]      FIGS. 1, 2 ,  3 , and  4  show different views of a wafer carrier that embody the inventions herein. The carrier is configured as a wafer container, such as a FOSB or FOUP, and is comprised principally of a container portion  20  with an open front  22 , a door  24  to close the open front, and a bottom plate  26 . The container portion generally has a top  30 , a bottom  32 , sides  34 , back  36 , bottom surface  37 , and an open interior  38 . Positioned in the interior at the sides of the container portion are wafer supports  40  for supporting wafers with a single wafer W illustrated in  FIG. 4 . Front opening wafer carriers know in the art have features such as illustrated in U.S. Pat. Nos. RE 28,221; 6,010,008; 6,267,245; commonly assigned with this application, all of which are incorporated herein by reference.  
         [0026]     Referring to  FIGS. 2, 3 ,  4 , and  6  details of the bottom plate are illustrated. The bottom plate has a top surface  44 , a bottom surface  46 , and a periphery  48 . Rail portions  50  for interfacing with conveyor, such as the conveyor  51  illustrated in  FIG. 3 , are located on the front side, back side, left side, and right side of the periphery of the plate. The plate has three kinematic coupling grooves  52  each having kinematic coupling surfaces  54  for engaging the prongs of a cooperating kinematic coupling interface on the processing equipment or other fixture upon which the container is seated. The plate has four apertures  60  which match cooperating apertures  62  on the bottom  37  of the container portion. In one embodiment, pronged bushings as illustrated in  FIG. 4  and  FIG. 7  may be utilized to extend through the aperture in the container portion and the aperture in the plate to secure the two aperture peripheries  64 ,  66  together. Additional structural ribbing  68  provides structural support and engagement contact with the bottom surface  37  of the container portion.  
         [0027]     Referring to  FIG. 8 , a further methodology and apparatus (spacer)  169  for connecting the bottom plate  26  to the container portion or shell  20  is disclosed. A first bushing  70  snaps into place into the aperture  72  in the shell and is secured in place by way of detents  76 . O-rings  78 ,  80  provide tightening and stability of the system as well as frictionally securing the first bushing in place. The first bushing has a bore  84 , a threaded end portion  86 , and a collar  88 . A second connecting member  92  configured as a second annular bushing snaps into place into an aperture  94 . In the plate detents  96  secure the second annular bushing in place within the aperture in the plate. The second annular bushing has an upper end  100  that is threaded to cooperate with the threaded end of the first annular bushing. The spacing between the conveyor plate  26  and the shell can be precisely adjusted by way of rotation, in this embodiment, of the second annular bushing  92  with respect to the first annular bushing  70 . Additional O-rings  102  provide a frictional means to retain the second annular bushing at the desired rotational position for the correct adjusted position. The filter/cartridge described below, a plug, or a filter may be deposited in the bore  84 .  
         [0028]     Referring to  FIGS. 9, 10 ,  11 , and  12  embodiments of a filter/valve cartridge  130 ,  132  are illustrated. The cartridges significantly have a duckbill valve member  138  that is preferably formed from injection molding a material and secondly slicing a slit  140  in the apex  142  of the duckbill valve member, thereby forming flaps  144  and  146 . The duckbill valve member is suitably positioned in place by way of collars  160  into a cartridge shell  164 . O-rings  168  may be utilized to seal the cartridge in place in a suitably sized aperture such as bore  84 . The cartridges of  FIGS. 9, 10 , and  11  also have a filter member  172 ,  174  made of suitable filtering material that is known in the art. Retention member  178 ,  180  respectively holds the filter members in place in the cartridge.  
         [0029]     Referring to  FIG. 13 , a further inventive aspect of the wafer carrier is illustrated and comprises an elastomeric dampener  190 . Said dampener is positioned intermediate the shell and the plate to absorb any shock imparted to the plate to minimize transference of same to the wafers. The elastomeric dampener, as illustrated by the numbers  190  in phantom in  FIG. 4 , may be positioned at the respective apertures  60 ,  62  of the plate shell. Alternatively, the elastomers can be placed using other suitable structural features at other locations in between the shell and plate. The bushing may be utilized to provide complete isolation that is in between the plate and the shell with no direct rigid plastic to rigid plastic contact between the shell and the plate. Alternatively there can be direct engagement between rigid components of the shell and the plate and the dampeners can be placed near the periphery of the plate to provide some measure of dampening at the plates periphery particularly when the conveyor rails  50  are in use for conveying the wafer carrier. In a further embodiment, the kinematic coupling can be integral with the shell or container portion and be exposed at the bottom; the plate can have the conveyor rails that engage a conveyor  51  as shown in  FIG. 3  and be isolated from the shell by the dampeners.  
         [0030]     Various materials are suitable for manufacturing the components of the wafer carrier. For example PEI with carbon fiber filler is suitable for the shell as well as the plate. Carbon fiber filled peek is also suitable but is more expensive. Polycarbonate particularly carbon powder filled polycarbonate may also be utilized but has less desirable characteristics with regard to flammability and smoke and fume generation when burning.  
         [0031]     Thus, various inventive aspects of the substrate carrier are described and portrayed herein. Said inventive aspects specifically include, without limitation, individually and in various combinations, the utilization of the elastomeric dampener intermediate the conveyor plate and the shell; the utilization of a plurality of relatively large diameter that is greater than one-half inch structural attachment members, extending through the shell and plate; utilization pronged bushings to secure the plate on the shell; utilization of connectors with bores extending therethrough that permit insertion of filter/valve cartridges within said bores; utilization of adjustable threaded members for positioning the precise location of the plate with regard to the wafer shell and wafer planes; utilization of O-rings to lock or secure the respective members in the appropriate position; utilization of threaded members for the adjustment and attachment that utilize a bore extending therethrough for insertion of a filter cartridge, valve cartridge, a combination of both, or a solid blank. The utilization of a valve configured as a duckbill valve formed from the elastomeric material to provide purging and/or pressure equalization is further provided.  
         [0032]     Although the features herein are illustrated generally with reference to semiconductor wafer containers, the inventive aspects also are applicable and claimed with respect to flat panel carriers, reticle carriers, film frame carriers and the like.