Abstract:
A substrate container including substrate supports, such as concentric rings, adapted to receive substrates in a substrate stack. The container includes a base and a top cover to enclose the substrate stack. A latching mechanism is adapted to latch the top cover to the base and secure the substrate stack within the container. The latching mechanism includes resilient corner flanges on an outside portion of the container, the flanges acting as springs to exert a biasing force on the cover and on the substrate stack. The flanges hold the stack within the container while accommodating stack-up uncertainty caused by the accumulation of uncertainties due to component machining tolerances. In some embodiments, a gap is created between a side wall of the top cover and the base of the container to assure compression of the substrate stack. Deflection limiters may be implemented to prevent over-deflection of the flanges.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 62/089,103, filed on Dec. 8, 2014, the disclosure of which is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    In general, substrate containers or carriers are used for transporting and/or storing batches of substrates such as silicon wafers or magnetic disks, before, during and after processing of the substrates. The substrates can be processed into integrated circuits and the disks can be processed into magnetic storage disks for computers. The terms wafer, disk, and substrate are used interchangeably herein and any of these terms can refer to semiconductor wafers, magnetic disks, flat panel substrates, and other such substrates, unless otherwise indicated. 
         [0003]    Semiconductor wafers, from which integrated circuits and the like are manufactured, are conventionally round in shape and made from silicon, which is highly brittle. Such wafers are subjected to a variety of processing steps in transforming the semiconductor wafer into integrated circuit components. The various processing steps are performed under ultra-clean conditions to minimize the potential of contamination of the wafers as they are being processed. Each wafer may be subjected to dozens if not hundreds of steps in its processing cycle. The potential for contamination and destruction of a wafer or reduction in yield is ever present throughout the various processing and packaging steps. Particularly during the steps that take place at fabrication facilities, any minute particulates can destroy the integrated circuit on which it falls. Once the processing steps of the wafers are completed they are generally shipped while still in wafer form to a facility that will dice and capsulate in integrated circuit packaging each individual circuit on the wafer. The terms wafer containers, carriers, shippers, cassettes, transport/storage bins, and the like, are used interchangeably herein unless otherwise indicated. 
         [0004]    Traditionally, during processing, storage and shipping of substrates, the substrates are supported and constrained at their edges to mitigate contact and possible damage and contamination to the faces of the substrates having the circuits thereon. 
         [0005]    Even as substrates are getting larger in scale, up to 450 millimeters and greater in diameter, the density of components is getting significantly greater. Moreover, disks also are getting thinner providing much thinner completed integrated circuit packages. Accompanying the trend towards larger, denser, and thinner substrates, the substrates are becoming more valuable, more brittle, and more easily damaged during shipment. For thinner, more fragile substrates, enclosures are utilized in which the substrates are stacked on top of one another about a central axis. 
         [0006]    Commonly assigned U.S. Pat. No. 7,040,487 to Zabka et al. (hereinafter “Zabka”) discloses a protective shipper including a cover and a base that are held together by a latching mechanism. The base is configurable to protect semiconductor wafers or other substrates within a storage pocket. The base includes a support wall that defines the storage pocket, and the cover encloses the storage pocket. The cover includes one or more latching apertures configured to minimize unintended unlatching. Commonly assigned U.S. Pat. No. 6,550,619 to Bores et al. (hereinafter “Bores”) discloses another shipper having a base, a cover and a latching mechanism. Zabka and Bores are hereby incorporated by reference herein in their entirety except for express definitions and patent claims contained therein. 
       SUMMARY 
       [0007]    Various embodiments of the disclosure include a container that accommodates substrate stacks of varying height due to the accumulation of dimensional uncertainties associated with fabrication tolerances. That is, components within the substrate container are subject to dimensional uncertainty due to specified machining tolerances, for example, of thickness and flatness of support rings. The resulting dimensional uncertainties of these components result in what is herein referred to as “stack-up uncertainty.” Rather than tightening the dimensional tolerance of the components, which would drive up fabrication costs, various embodiments of the disclosure describe substrate containers that readily accommodate a wide range of stack-up uncertainty. 
         [0008]    For some embodiments of the disclosure, the same mechanism that enables the wide range of stack-up uncertainty also provides effective cushioning of the substrate carrier and its contents against shock. 
         [0009]    Structurally, various embodiments of the disclosure present a substrate container or shipper that includes substrate supports, in the form of concentric rings, adapted to receive substrates in a stack. The container includes a base and a top cover to enclose the substrate stack. A latching mechanism is adapted to latch the base and top cover with respect to each other and secure the substrate stack within the container. The latching mechanism includes deflectable, biased corner flanges on an outside portion of the container, the flanges acting as springs to create load on the cover and on the substrate stack. The flanges hold the stack within the container while accommodating stack-up uncertainty. A gap is created between a side wall of the top cover and the base of the container. Deflection limiters prevent over-deflection of the flanges. Embodiments of the disclosure can be used with containers accommodating multiple different substrate sizes, for example 150 mm, 200 mm, 300 mm and 450 mm substrates, to name several examples. Other aspects will be apparent to those of ordinary skill upon reading this disclosure, and this Summary should not be considered limiting. 
         [0010]    In various embodiments of the disclosure, a container for substrates defining a substrate storage area adapted to receive a plurality of stacked substrates is disclosed, the container including a base having an upwardly extending side wall, the side wall being disposed to at least partially surround the substrate storage area, the base further including at least one resilient latching member extending upwardly from the base, the latching member including an engagement portion having a substantially downwardly facing engagement surface. A cover includes a downwardly extending side wall, the cover cooperating with the base to at least partially surround the substrate storage area. At least one deflectable corner flange is operably coupled to the cover and extending radially outwardly relative to the side wall of the cover, the deflectable corner flange being constructed and arranged to be deflectable downwardly relative to the cover, the deflectable corner flange defining an aperture adapted to receive the latching member. The deflectable corner flange defines an upper surface adapted to engage the engagement portion of the latching member to latch the cover with respect to the base. A deflection limiter may be at least partially disposed on the latching member below the deflectable corner flange to engage and limit downward deflection of the deflectable corner flange. 
         [0011]    In some embodiments, the at least one deflectable corner flange includes at least four deflectable corner flanges distributed around the cover, and the at least one latching member includes at least four latching members distributed around the base and generally aligned with the at least four corner flanges. The latching member may define a hook portion having a cam surface adapted to engage an edge of the aperture of the deflectable corner flange such that downward movement of the cover and corner flange together relative to the base applies force to the cam surface to bias the latching member toward a central axis of the container. In some embodiments, the corner flange is constructed and arranged such that deflection of the corner flange relative to the cover causes the hook portion to clear the aperture and causes the latching mechanism to snap radially outwardly to a latching position. The engagement portion of the latching member may engage the upper surface of the corner flange to latch the cover with respect to the base. In certain embodiments, the cam surface defines two cam surface portions adapted to engage said aperture edge, the two cam surface portions defining a gap therebetween. Each latching member may define a side surface and a base surface at an upper portion thereof, the side surface and the base surface being disposed to define the gap between the two cam surface portions. In some embodiments, the base surface defines a central opening defined at a bottom of the gap between the two cam surface portions. The central opening may be disposed directly above and in line with the deflection limiter. The corner flange may define a push pad adapted to receive downward force to deflect the corner flange. In some embodiments, the deflectable corner flange is molded as one-piece with the cover. 
         [0012]    In various embodiments of the disclosure, a substrate container is disclosed, including a plurality of substrate supports adapted to receive substrates in a substrate stack within the container. First and second case portions define outer structure of the container and enclose the substrate supports. A latching mechanism is adapted to latch the first and second case portions with respect to each other and secure the substrate stack within the container. The latching mechanism includes a deflectable tab secured to and disposed at a radially outward position of the first case portion, the latching mechanism including a latching member secured to and disposed at a radially outward portion of the second case portion. The deflectable tab may define an opening therein, the opening adapted to receive the latching member to latch the first and second case portions together. In some embodiments, the deflectable tab is biased against the latching member to apply compressive force against the substrate stack through one of the case portions such that substrate stack is held fast within the first and second case portions. 
         [0013]    The substrate stack may create a hard stop against movement of the first and second case portions with respect to each other. The substrate stack may also create a gap between the first and second case portions. In various embodiments, a deflection limiter is at least partially attached to the latching member to limit deflection of the tab. The deflection limiter may include a rib rotatable about a hinge disposed on the latching member, and a pocket defined by the deflectable tab adapted to receive the rotatable rib. 
         [0014]    In various embodiments of the disclosure, a container for substrates in combination with a substrate stack is disclosed. The container includes a base having a perimeter and a side wall extending upwardly inside the perimeter and defining a storage pocket containing the substrate stack inside the side wall, the base including a pair of resilient latching members positioned between the perimeter and the side wall, each latching member having an upright portion with a hook portion having a downwardly facing engagement surface. In some embodiments, a cover has a perimeter and a side wall extending downwardly inside the perimeter, the cover being disposable on the base to enclose the storage pocket, the cover including deflectable flanges defining a pair of latching apertures. The flanges may each define a surface adapted to receive a respective downwardly facing engagement surface adjacent to the latching aperture, the latching apertures positioned between the perimeter of the cover and the side wall of the cover and corresponding to the pair of latching members, whereby when the pair of latching members are engaged with the cover at the pair of apertures, the cover is latched with respect to the base. In some embodiments, the substrate stack includes a plurality of substrates and a plurality of substrate supports. In some embodiments, the deflectable flanges are deflected when the cover is latched with respect to the base, the deflected flanges applying pressure to the latching members to draw the cover toward the base and to cause the cover to apply pressure to the stack to hold the stack within the container. In some embodiments, the cover contacts and applies compressive force against the stack, the stack adapted to stop the cover from movement toward the base when the cover is latched with respect to the base. The stack may be adapted to prevent the side wall of the cover from closing a gap between the base and the side wall of the cover when the cover is latched with respect to the base. The cover may press and seal against an uppermost substrate support when the cover is latched with respect to the base. The deflection of the flanges may accommodate stack-up uncertainty height variations from stack to stack. In some embodiments, the flange surface adapted to receive the respective downwardly facing engagement surface of the hook portion defines a latching recess within the flange. The latching recess may be angled downwardly with respect to a remainder of the flange, and the engagement surface of the hook portion is angled downwardly to correspond to the latching recess. The downward angle of the engagement surface and the downward angle of the latching recess are adapted to deflect the flange downwardly when the cover is latched with respect to the base. 
         [0015]    In various embodiments of the disclosure, a combination of a container for substrates and a plurality of substrates is disclosed, the combination including a container base, a container cover, a plurality of substrate supports disposed within the container, and a plurality of substrates disposed substantially concentrically within the container on the substrate supports. A fastening mechanism may be adapted to secure the base and cover together and secure the plurality of substrates within the container, the fastening mechanism including a bendable flange coupled with the cover and bendable with respect to the cover, the bendable flange defining an aperture. The fastening mechanism may also including a biased fastening member connected to the base, the biased fastening member being constructed to extend through the aperture and spring into a fastening position within the aperture to fasten the cover with respect to the base. In some embodiments, the biased fastening member defining first and second engagement surfaces adapted to contact opposite sides of the bendable flange adjacent the aperture and limit bending of the bendable flange in opposite directions. In some embodiments, only one of the first and second engagement surfaces at a time is able to contact the bendable flange and limit bending of the bendable flange in a respective one of the opposite directions. 
         [0016]    In various embodiments of the disclosure, the substrates are semiconductor wafers. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a perspective view of a substrate container, according to an embodiment of the disclosure; 
           [0018]      FIG. 2  is a perspective cutaway view of the substrate container of  FIG. 1 ; 
           [0019]      FIG. 3  is a partially exploded view of the substrate container of  FIG. 1 ; 
           [0020]      FIG. 4  is an upper perspective view of a latching member of the substrate container of  FIG. 1 ; 
           [0021]      FIG. 5  is a lower perspective view of the latching member of  FIG. 4 ; 
           [0022]      FIG. 6  is a lower perspective view of a latching mechanism of the substrate container of  FIG. 1 ; 
           [0023]      FIG. 7  is an upper perspective view of a deflectable flange of the substrate container of  FIG. 1 ; 
           [0024]      FIG. 8  is a perspective cross-sectional view of the deflectable flange of  FIG. 7 ; 
           [0025]      FIG. 9  is a partially cut-away side view of a latching mechanism of the substrate container of  FIG. 1  in a radially inwardly biased position; 
           [0026]      FIG. 10  is a partially cut-away side view of a latching mechanism of the substrate container of  FIG. 1  in a latching position; 
           [0027]      FIG. 11  is an upper perspective view of the latching mechanism of  FIG. 10 ; 
           [0028]      FIG. 12  is a partial cut-away side view of the substrate container of  FIG. 1  in a pre-latched configuration; 
           [0029]      FIG. 13  is a partial cut-away side view of the substrate container of  FIG. 1  in a latched configuration; 
           [0030]      FIG. 14  is a partially cut-away side view of a latching mechanism in a radially inwardly biased position, according to an embodiment of the disclosure; 
           [0031]      FIG. 15  is a partially cut-away side view of a latching mechanism in a latching position, according to an embodiment of the disclosure; 
           [0032]      FIG. 16  is a bottom perspective view of a deflection limiter according to an embodiment of the disclosure; 
           [0033]      FIG. 17  is top perspective view depicting a feature of the limiter of  FIG. 11 ; and 
           [0034]      FIG. 18  is a bottom perspective view depicting the limiter of  FIG. 11  in an alternate position. 
       
    
    
     DETAILED DESCRIPTION 
       [0035]    Referring to  FIGS. 1-3 , a container  100  is depicted in an embodiment of the disclosure. The depicted container  100  is a shipper for transporting, storing, and/or protecting 300 mm substrates  105  such as semiconductor wafers or other according to embodiments of the disclosure. The 300 mm shipper is depicted for illustrative purposes only, and it should be appreciated that shippers for smaller or larger substrates are included herein. The container  100  generally includes two cooperating portions, configured as a base  110  and a top cover  115 . Top cover  115  enters into proximity with base  110  at interface region  120 , and top cover  115  and base  110  are secured with respect to each other by latching mechanisms  125 . Four latching mechanisms  125  are illustrated, but those of skill in the art will recognize that two, six, or any desired number of latching mechanisms are also contemplated in keeping with the disclosure. 
         [0036]    Container  100  includes a plurality of substantially arcuate lateral substrate supports  130 , in the form of generally concentric rings, for example, constructed to support substrates  105  in substrate stack  133  extending along central axis  134  of container  100 . Supports  130  extend laterally inwardly relative to a generally cylindrical, downwardly extending, side wall  135  of cover  115 . A non-limiting example of substrate supports  130  are disclosed, for example, at commonly assigned International Publication No. WO 2015/130690, published Sep. 3, 2015, the disclosure of which is hereby incorporated by reference in its entirety except for express definitions and patent claims contained therein. 
         [0037]    Supports  130  may be molded or otherwise formed of plastic or other suitable material. In various embodiments, supports  130  are made of polypropylene. The supports  130  may be constructed of other materials including, but not limited to, polycarbonate or acetals. In some embodiments, the materials include a statically-dissipative filler, such as a carbon powder filler, for dissipation of static electricity. 
         [0038]    Side wall  135  generally defines substrate stack pocket  138  for accommodating a substrate stack  133 . Side wall  135  extends downwardly around an outside portion  137  of cover  115  and at least partially defines an outer perimeter  139  of cover  115 . Floor  140  of container  100  is positioned at the bottom of pocket  138 . Additionally, base  110  defines a side wall  145  extending upwardly around an outside portion of base  110  and is spaced inwardly from an outer periphery  146  of base  110 . Side wall  145  may be generally arcuate or curved and is segmented into four side wall portions  147 , according to the illustrated embodiment. 
         [0039]    Herein, the terms “upward” and “upwardly” refer to a direction having a vector that extends in a positive z-direction, in accordance with a cylindrical coordinate system  143  of arbitrary origin (e.g.,  FIGS. 2 and 3 ). The terms “downward” and “downwardly” refer to a direction having a vector that extends in a negative z-direction, in accordance with the cylindrical coordinate system  143 . The terms “outward” and “outwardly” refer to a direction having a vector that extends in a positive r-direction, in accordance with the cylindrical coordinate system  143 . The terms “inward” and “inwardly” refer to a direction having a vector that extends in a negative r-direction, in accordance with the cylindrical coordinate system  143 . 
         [0040]    In some embodiments, base  110  defines protruding structure configured as shoulders  150 , each defining an upper surface  155 . Extending upwardly from upper surface  155  of each shoulder  150  is a latching member  160 , constituting a portion of latching mechanism  125 . 
         [0041]    Cover  115  defines deflectable corner tabs or flanges  162 , disposed directly above corresponding shoulders  150  and at least partially defining the outer perimeter  139  of cover  115 . Flanges  162  are constructed and arranged to deflect downwardly with respect to a remainder of cover  115 . In that regard, flanges  162  may be constructed free of ribs or other structural strengthening aspects that would tend to prevent or hinder such deflection. Flanges  162  each define an upper surface  163  and an aperture  164  for receiving a respective latching member  160 , as will be described further, and thus form part of each latching mechanism  125 . Each aperture  164  defines outdents  165 , as described below in reference to  FIGS. 7 and 8 . Each deflectable corner flange  162  of cover  115  is formed or accommodated within a respective recess or groove  166  disposed in side wall  135 . Although four sets of shoulders  150  and flanges  162  are illustrated, those of skill in the art will recognize upon reading this disclosure that two, six, or any desired number of sets are also contemplated in keeping with the disclosure. 
         [0042]    In certain embodiments, shoulders  150  and latching members  160  are integrally molded as one piece with base  110 , and deflectable flanges  162  are integrally molded as one piece with cover  115 , according to aspects of the disclosure. Plastics or other materials suitable for molding or otherwise forming base  110 , cover  115 , and other components of container  100  will be apparent to those of ordinary skill upon reading this disclosure. 
         [0043]    Referring additionally to  FIGS. 4-6 , latching member  160  of each latching mechanism  125  is disposed upright, or standing, and extends substantially upwardly with respect to shoulder  150  of base  110 . Latching member  160  optionally defines a generally tapered shape bottom-to-top, being wider at a lower end  181  of base  110  than at an upper end  182 , for easier insertion and locking within a corresponding latch opening or aperture  164 . Latching member  160  may be connected to or molded with base  110  by substantially horizontal portion  170 , which reduces a spring constant of latching member  160  in a generally vertical direction, i.e., in a direction generally parallel to central axis  134  of container  100 , by allowing up and down flex of member  160 . Member  160  is also generally flexible or rotatable in a radial direction with respect to container  100 , generally transverse to central axis  134 , as indicated by arrow  175 , such that member  160  flexes radially inwardly from and radially outwardly to the as-molded position illustrated in  FIG. 4 . 
         [0044]    In the depicted embodiments, the latching member  160  depicted as being actuated inwardly, toward the center of the container  100 . It is noted that a latching member that is actuated outwardly is also contemplated, though not depicted. 
         [0045]    Latching member  160  includes hook portion  185  having downwardly facing engagement surface  187 . In some embodiments, such as depicted in  FIG. 5 , in the as-molded or unflexed position, engagement surface  187  angles downwardly with respect to the horizontal, i.e. downwardly with respect to upper surface  155  of shoulder  150  and upper surface  163  of flange  162 . Engagement surface  187  may include two engagement surface portions  188 ,  189 . In some embodiments, hook portion  185  also defines a cam surface  190 , optionally formed as two cam surface portions  191 ,  192 , that define an intervening gap  194 . Gap  194  is bordered by generally upright surface  195  and generally curved base portion  196  of hook portion  185 . 
         [0046]    In various embodiments, each latching member  160  further includes deflection limiter or stop  200 , which may be molded integrally as one piece therewith. Deflection limiter  200  may be disposed centrally along latching member  160  and includes a top engagement surface  205  having a base  210  and angled sides  215 . Together, base  210  and sides  215  define an engagement pocket or recess  218 . In various embodiments, deflection limiter  200  is tapered top to bottom, as depicted in  FIG. 5 . Deflection limiter  200  may be disposed directly below a gap  220  formed in curved base portion  196  of hook portion  185 , to simplify mold tooling. Gap  220  avoids the need for mold action during formation of latching member  160 , for example. 
         [0047]    Bottom surface  225  ( FIG. 6 ) of each deflectable flange  162  includes a protrusion or ridge  230  aligned with and extending along a width of aperture  164 . Protrusion  230  includes a base  235  and side edges  240 , which may correspond to base  210  and sides  215  of engagement recess  218  of deflection limiter  200 . 
         [0048]    Referring to  FIGS. 7-8 , an aperture  164  defined by each deflectable flange  162  of cover  115  is depicted in more detail according to an embodiment of the disclosure. Aperture  164  includes outdents or notches  165 , creating a generally “T”-shaped aperture. Each flange  162  may also include push pad  245 , raised with respect to a remainder of flange  162 , for receiving downward force to deflect flange  162  with respect to a remainder of cover  115 . Further, each flange  162  defines latching recess  246  for receiving engagement surface  187  of hook portion  185 . Latching recess  246  is optionally sloped downwardly relative to the horizontal, or relative to upper surface  163  of flange  162 , to receive corresponding downwardly sloped engagement surface  187  of hook portion  185 . In some embodiments, the shape and slope of latching recess  246  matches the shape of protrusion  230  on bottom surface  225  of flange  162 . 
         [0049]    Functionally, and again in reference to  FIGS. 4-6 , forming hook portion  185  with two cam surface portions  191 ,  192 , and two engagement surface portions  188 ,  189 , separated by gap  194 , as illustrated, helps maintain more consistent thickness of the plastic or other material forming hook portion  185 , lessens the possibility of “sink” or other molding defects if gap  194  were filled in with material, and reduces potential rubbing contact between cam surface  190  and aperture  164 , and between engagement surface  187  and upper surface  163  of flange  162 , and consequent potential particulate generation, according to aspects of the disclosure. The corresponding shapes of the protrusion  230  and engagement recess  218  help guide protrusion  230  into engagement recess  218  upon downward deflection of flange  162  relative to the remainder of cover  115 , as will be described. Outdents  165  of the generally “T”-shaped aperture tend to prevent unintended unlatching of latching mechanism  125  when cover  115  is rotated or otherwise inadvertently displaced with respect to base  110 , or when latching member  160  receives unintended force. Latching member  160  has to receive a generally perpendicular unlatching force relative to central axis  134 , and avoid outdents  165 , for unlatching to occur. Further advantages of aperture  164  in this regard are described in U.S. Pat. No. 7,040,487, previously incorporated by reference herein. Deflection limiters  200  substantially prevent each flange  162  from downward over-deflection. The distance between limiter  200  and bottom surface  225  of flange  162  is chosen to allow a desired amount of maximum deflection, depending, for example, on the thickness and material of flange  162 . The distance between limiter  200  and that illustrated in the figures is not necessarily to scale. Limiter  200  creates a stop location for flange  162  to substantially prevent breakage, permanent deformation, an unacceptably loose latching fit, and other problems ultimately resulting from unlimited or excessive deflection of flange  162 . 
         [0050]    Limiting deflection has utility in both an operational and a non-operational context. In an operational context, when downward pressure is applied to push pad  245  to cause latching member  160  to snap into a latching position, for example, protrusion  230  will be received and stopped within engagement recess  218  of limiter  200  once a downward travel limit of flange  162  is reached. In a non-operational context, deflection limiter  200  may limit deflection of flange  162  that can occur when a latched container  100  is vacuum-sealed in plastic, for example, or subject to other external deflection forces, such as impact loads during shipping. 
         [0051]    Referring to  FIGS. 9-13  and again to  FIG. 2 , operation of container  100  is depicted in an embodiment of the disclosure. Substrate stack  133  is positioned initially within base  110  and/or cover  115  of container  100 . Cover  115  is placed over base  110  for latching, such that latching members  160  enter respective apertures  164  within deflectable corner flanges  162 . As cover  115  and thus flanges  162  are translated downwardly along central axis  134 , cam surfaces  190  engage respective apertures  164  and deflect or rotate each latching member  160  inwardly toward central axis  134 , as depicted by arrow  250 . Hook portion  185  fills a substantial portion of aperture  164 . A lower portion of cover  115 , specifically a lower end of side wall  135 , substantially enters interface region  120  between base  110  and cover  115 . According to certain embodiments, a suitable upper internal portion of cover  115  is brought into contact with and engages wafer stack  133 , specifically an uppermost concentric ring  130  thereof. 
         [0052]    When flange  162  and latching member  160  are in an initial pre-latched position, as illustrated in e.g.  FIG. 9 , a user then applies downward force on push pads  245  ( FIG. 11 ) or another portion of flange  162 , causing downward deflection, bending or rotation of each flange  162  with respect to a remainder of cover  110 , as indicated by arrow  255  in  FIG. 10 . Once continued deflection causes hook portion  185  to substantially clear aperture  164 , the bias of latching member  160  towards its as-molded position causes latching member  160  to snap radially outwardly, as indicated by arrow  260 . Downwardly facing engagement surface  187  of hook portion  185  slides over and into engagement with upper surface  163  of downwardly deflected flange  162 , and is at least partially accommodated by correspondingly downwardly sloped latching recess  246 . It should be noted that the precise downward slope in  FIGS. 9-10  is not necessarily to scale, for purposes of illustration.  FIG. 11  also depicts latching member  160  in its latched position. 
         [0053]    Once latching member  160  reaches the latched position relative to flange  162  ( FIGS. 10-11 ), the user releases the downward force on push pad  245 , causing downwardly deflected flange  162  to at least partially spring upwardly, in a direction opposite to that indicated by arrow  255 , and cause increased pressure and locking contact between flange  162  and engagement surface  187 . The downwardly angled disposition of engagement surface  187  and deflection recess  246  optionally tends to maintain each flange  162  in a partially downwardly deflected position, thereby maintaining upwardly directed spring pressure by flanges  162  on hook portions  185  as the resilience of flanges  162  naturally tend to return to the as-molded position. Each flange  162  may remain partially deflected even when container  100  is in transport, for example, and the resulting deflection/spring force enhances and holds contact pressure of cover  115  relative to base  110 . Cover  115  thus is pulled into tighter contact with respect to base  110  due to the continuous spring action of deflected flange  162 . 
         [0054]    To release cover  115  from latched contact with respect to base  110 , a user presses inwardly on each latching member  160 , in a direction opposite to arrow  260 . In the case where flange  162  is still partially deflected, this inward pressure causes flange  162  to pop up relative to hook portion  185  and latching member  160 , in a direction opposite to that of arrow  255 , once engagement surface  187  moves completely into/over aperture  164  and clears recess  246  and upper surface  163  of flange  162 . Compressive latching pressure between cover  115  and substrate stack  133 , and/or between cover  115  and base  110 , is thereby released, and cover  115  can be readily removed. 
         [0055]    According to various embodiments of the disclosure, cover  115  exerts pressure directly on substrate stack  133 , tending to press stack  133  into or toward floor  140  of container  100 . Some embodiments of the disclosure create a compression force exerted on substrate stack  133  in a range of 5 lbf (pounds-force) to 10 lbf inclusive. Herein, a range that is said to be “inclusive” includes the end point values of the stated range. In some embodiments, the range of compressive force is 7 lbf to 9 lbf inclusive. Some embodiments create about 8 lbf of compression. 
         [0056]    In some embodiments, due to tolerances or long term creep of the flanges  162 , there may not always be a compression force applied by the flanges  162 . This is acceptable functionally because, in certain embodiments, container  100  with substrate stack  133  assembled therein is shipped in a vacuum bag (not depicted) and or secondary foam packaging (not depicted). The vacuum bag/secondary packaging may maintain the container  100  in sufficient compression. 
         [0057]    In one embodiment, cover  115  makes hard contact with an uppermost ring or support  130  of stack  133 . As described in U.S. Provisional Patent Application No. 62/089,087, this hard contact may create a seal and an air cushion to protect stack  133  and especially the uppermost substrate  105  thereof. The larger the substrate diameter, especially 300 mm and greater diameter substrates, the more important it can be to protect the uppermost substrate in this manner. Stack  133  itself thus serves as a hard stop against cover  115 , enhancing stability and security of substrate stack  133  within pocket  138  of container  100 , without damaging individual substrates  105 . U.S. Provisional Patent Application No. 62/089,087, which is commonly assigned, is hereby incorporated by reference herein in its entirety, except for patent claims and express definitions contained therein. 
         [0058]    Additionally, stack-up uncertainty of the rings is easily accommodated due to the spring action of flanges  162 . In an embodiment where stack  133  includes, for example, twenty six rings, a ring molding tolerance of a mere 0.001 in. (one one-thousandth of an inch) can result in relatively significant ring height and stack height variability from stack to stack, over the height of the entire stack. Such stack-up uncertainty thus can be, for example, on the order of about 0.026 in., or in the range of about 0.020 in. to about 0.032 in. inclusive, or in the range of about 0.026 in. to about 0.052 in. inclusive, or in a range of up to about 0.1 in. inclusive or more. Other stack-up uncertainties of greater or lesser dimension will be apparent to those of ordinary skill upon reading this disclosure. By building in deflection using corner flanges  162  of container  100 , optionally in combination with horizontal portion  170  described previously, such uncertainty and variability is easily accommodated, allowing the previously mentioned air seal to be readily created. 
         [0059]    Because cover  115  has a hard stop against, and generates compressive pressure on, stack  133 , a small gap  262  may be created between cover  115  and base  110  in interface region  120  that exists even when cover  115  and base  110  are fully latched with respect to each other. Stack  133  is secured between and prevents the base  110  and cover  115  from moving closer to each other. In some embodiments, a gasket or seal assembly (not depicted) is disposed in the gap  262 , making sealing contact with both the base  110  and the cover  115 . 
         [0060]    Referring to  FIGS. 12-13 , assembly of a loaded container  100  is depicted in an embodiment of the disclosure. In  FIG. 12 , cover  115  is moving into interface region  120 . In  FIG. 13 , cover  115  compresses against stack  133  at the topmost portion thereof (e.g.  FIG. 2 ), leaving gap  262  at the bottom of cover  115 , and specifically at the lower end of side wall  135  thereof, where it would otherwise contact base  110 . Gap  262  helps ensure that contact occurs between cover  115  and stack  133  instead between cover  115  and base  110 , which could cause a looser fit and rattling of stack  133  within container  100 , for example. Stack  133 , cover  115 , and base  110  thus all work together for protection and containment of substrates  105  against external impact shocks on container  100 , for example caused by inadvertent dropping. Other related features and advantages are described in the above-identified commonly assigned U.S. 62/089,087, incorporated by reference above. It should be noted that according to alternative embodiments, cover  115  can be pulled into direct contact with base  110  at interface region  120 , and stack  133  can be secured tightly within container  100  using alternative methods. 
         [0061]    Referring to  FIGS. 14-15 , latching mechanism  125  is depicted according to an embodiment of the disclosure. For purposes of illustration, post-latched, in-use deflection of each flange  162  is not necessarily to scale. According to this embodiment, deflection recess  246  of  FIGS. 9 and 10  is eliminated or reduced in depth, resulting in increased deflection angle relative to the deflection illustrated at  FIG. 10 . Conformance to the downwardly sloped engagement surface  187  may also cause local twisting of flange  162  as depicted. Other characteristics remain as described previously. 
         [0062]    Referring to  FIGS. 16-18 , a deflection limiter  300  is depicted in an embodiment of the disclosure. Limiter  300  includes rib  305  that extends outward from cover  115  beneath flange  162 . A registration structure  340  may be disposed on bottom surface  225  of flange  162  for securing rib  305  in a deployed orientation that is substantially aligned in the radial direction r. In the depicted embodiment, the registration structure  340  includes a ramp block  315  having an inclined surface  320 , and a stop block  325 . A slot  330  is defined between ramp block  315  and stop block  325 , the slot  330  being sized to capture rib  305  between ramp block  315  and stop block  325 . 
         [0063]    In fabrication, rib  305  may be formed by use of a pass-through core (not depicted) in the portion of the mold that forms flange  162 . The pass-through core provides a clearance  345  between bottom surface  225  of flange  162  and an upper edge  350  of rib  305 . In some embodiments, an artifact of the pass-through core is a slot  335  defined in flange  162  that is aligned over rib  305  in the as-molded configuration. 
         [0064]    Functionally, living hinge  310  enables selective, manual rotation of rib  305  with respect to latching member  160 . Molded on bottom surface  225  of deflectable flange  162 . Clearance  345  enables rib  305  to rotate, if needed, about the living hinge  310  for setting in the operative position. Clearance  345  also defines the amount of deflection that flange  162  will undergo before engaging limiter  300 . 
         [0065]    In use, an operator rotates rib  305  from its as-molded, initial position depicted in  FIG. 16 , sliding up and over ramp block  315 , to clip into an operative position within slot  330  as depicted in  FIG. 18 . Deflection limiter  300  limits downward deflection of flange  162  substantially in a manner and with advantages described previously herein, with an additional advantage of optional deployment. The use of the pass-through core may also accurately provide a smaller deflection clearance between flange  162  and limiter  300  for tighter deflection control. 
         [0066]    The embodiments described above are intended to be illustrative and not limiting. Additional embodiments are within the claims. Although the present disclosure describes particular embodiments, those skilled in the art will recognize that changes may be made in form and substance without departing from the spirit and scope of the disclosure. 
         [0067]    Each of the additional figures and methods disclosed herein can be used separately, or in conjunction with other features and methods, to provide improved devices and methods for making and using the same. Therefore, combinations of features and methods disclosed herein may not be necessary to practice the disclosure in its broadest sense and are instead disclosed merely to particularly describe representative and preferred embodiments. 
         [0068]    Various modifications to the embodiments may be apparent to one of skill in the art upon reading this disclosure. For example, persons of ordinary skill in the relevant arts will recognize that the various features described for the different embodiments can be suitably combined, un-combined, and re-combined with other features, alone, or in different combinations. Likewise, the various features described above should all be regarded as example embodiments, rather than limitations to the scope or spirit of the disclosure. 
         [0069]    Persons of ordinary skill in the relevant arts will recognize that various embodiments can include fewer features than illustrated in any individual embodiment described above. The embodiments described herein are not meant to be an exhaustive presentation of the ways in which the various features may be combined. Accordingly, the embodiments are not mutually exclusive combinations of features; rather, the claims can include a combination of different individual features selected from different individual embodiments, as understood by persons of ordinary skill in the art. 
         [0070]    Any incorporation by reference of documents above is limited such that no subject matter is incorporated that is contrary to the explicit disclosure herein. Any incorporation by reference of documents above is further limited such that no claims included in the documents are incorporated by reference herein. Any incorporation by reference of documents above is yet further limited such that any definitions provided in the documents are not incorporated by reference herein unless expressly included herein. 
         [0071]    References to “embodiment(s)”, “disclosure”, “present disclosure”, “embodiment(s) of the disclosure”, “disclosed embodiment(s)”, and the like contained herein refer to the specification (text, including the claims, and figures) of this patent application that are not admitted prior art. 
         [0072]    For purposes of interpreting the claims, it is expressly intended that the provisions of 35 U.S.C. 112(f) are not to be invoked unless the specific terms “means for” or “step for” are recited in the respective claim.