Abstract:
A protective shipper comprises a cover and a base that are held together by a latching member. The base is configurable to retain and protect semiconductor wafers or film frames with wafers within a storage pocket. The base comprises latching member and a support wall that defines a storage pocket. The cover encloses the storage pocket. One or both of the cover may receive recesses for gripability. The cover may receive one or more latching apertures configured to minimize unintended unlatching. The shipper of the present invention may be manufactured in a mold capable of producing film frame or wafer containing configurations of the shipper by using an interchangeable mold insert.

Description:
REFERENCES TO RELATED APPLICATIONS  
       [0001]    This application is based upon U.S. Provisional Application Serial No. 60/305,422, which is hereby incorporated by reference herein. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention relates to carriers for semiconductor wafers and film frames, and more particularly relates to shippers for same.  
         BACKGROUND OF THE INVENTION  
         [0003]    Integrated circuits are manufactured from semiconductor wafers that are conventionally round in shape and made of highly brittle silicon. Such wafers are subjected to a variety of processing steps in transforming the semiconductor wafer into integrated circuit components. The various processing steps must be 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 encapsulate, in integrated circuit packaging, each individual circuit on the wafer.  
           [0004]    The stringent particulate control that takes place during the processing steps is generally not necessary in shipping the completed wafers to the facility that dices and packages the individual circuits.  
           [0005]    Traditionally, during the processing, storage and shipping of semiconductor wafers, the wafers are supported and constrained at their edges to prevent any contact, possible damage and contamination to the faces of the wafers having the circuits thereon.  
           [0006]    Even as semiconductor wafers are getting larger in scale, now up to 300 millimeters in diameter, the density of components is getting significantly greater. Moreover, disks are also are getting thinner, providing much thinner completed integrated circuit packages. This has been driven, at least in part, by the cellular phone industry that has sought thinner cell phones.  
           [0007]    Accompanying the trend towards larger, more dense and thinner wafers, the wafers are becoming more valuable, more brittle and more easily damaged during shipment. Although it is possible, desirable, and common to ship thicker wafers in enclosed containers that would support the wafers exclusively by their edges, using such devices to ship the thinner wafers has proven problematic due to breakage and damage of the wafers.  
           [0008]    Thus, for the thinner more fragile wafers, enclosures are utilized which have the wafers axially stacked on top of one another and separated by layers of paper-like flexible sheet material. Thus, the support of each wafer is by adjacent wafers and the entire stack of wafers. Foam material, such as urethane, is used to cushion the top and bottom of the stack.  
           [0009]    Such shippers can also be configured to receive film frames. The film frames are packaged similar to the wafers and protected during transport.  
           [0010]    One type of prior art wafer carrier is disclosed in U.S. Pat. No. 5,553,711 to Lin. Lin discloses a container that has a base, upright sidewalls defining a circular pocket, wafer dividers and a cover that comes down and threadingly attaches to the base.  
           [0011]    [0011]FIG. 1 discloses a conventional wafer carrier in which the enclosure is defined by a cookie tin-like plastic container having a bottom  50 , a top lid  52 , and utilizing a circular urethane foam bottom cushion  54 , and sheet material  56  interspersed between the wafer  58 .  
           [0012]    Referring to FIGS. 2 and 3, another wafer shipper is disclosed for shipping the stacked wafers with dividers therebetween. This wafer shipper has a base  60  and a top cover  62 . The base and top cover are injection molded and have circular shaped and axially-extending structural members  64  in the base component. Similarly, the top cover has axially-extending circular structural members  64  and radially extending ribs  66  that also project axially.  
           [0013]    These stacking wafer shippers may be either manually handled, robotically handled or both. Thus, means for opening and closing such containers must be both manually and robotically operable, and for manual purposes should be intuitive as well as simple, and reliable and quick. Various means are known for latching such wafer shippers. These include threads, such as shown in prior art FIG. 1, or a snap-on seal as shown in prior art FIGS.  2 - 3 . Other means for latching are a minimal rotation thread as shown in the embodiment of prior art FIG. 4, and axially-projecting spring latches as discussed hereinbelow.  
           [0014]    Wafer shippers that use the threaded engagements are awkward and subject to misalignment and improper attachment. These wafer shippers visually appear symmetrical in at least two planes, and therefore, there are typically four different options in assembling a top cover to a bottom cover. However, conventional prior art shippers generally require that the top cover be assembled in a specific orientation for proper latching.  
           [0015]    U.S. Pat. No. 6,193,068 to Lewis, et al., discloses another type of conventional shipper featuring axially-extending spring latches and utilizing a double wall to define the pocket for the stack of wafer carriers. Said double wall thickness is defined by two spaced thin wall sections which are not attached to one another extending from the base. This configuration appears to allow the individual unsupported thin walls supported only at the base to take on and retain deformation. The concentric arrangement of the thin walls makes any such deformation visibly apparent. The double sidewall in this prior art embodiment may help to isolate direct impact on the top cover from direct communication from top cover structure to the wall defining the wafer pocket.  
           [0016]    In the minimal rotation latch embodiment shown in FIG. 4, any separation stress will occur as illustrated by gap G. Such loading of the wafer shipper also can cause the deformation of the otherwise planar corners of the base to be stressed out of position, causing wobbling when placed on a planar surface and error in seating when placed on a machine interface. Such deformation can be caused in part by an overloading condition and also in part by the structural configuration of the wafer shipper.  
           [0017]    It would be desirable to provide sufficient structure in the base of such wafer shipper to prevent such distortion and bowing. Moreover, it would be highly desirable to provide a wafer carrier that has indicating means therein to prevent such an overloaded condition.  
           [0018]    Other minimal rotation latched shippers may use stunted threads that allow the wafer carrier to be rotated less than 30° to accomplish the latching. Such wafer carrier has the difficultly of requiring relatively precise angular positioning for initial placement of the top cover on the base before said rotation.  
           [0019]    Other embodiments may use axially-projecting double thin walls. Such embodiments provide double sidewalls are connected at the ends of each segment. Thus, four separate wall portions are defined, all of which are distinct from one another and integral with the base. Due to the connecting portions, which connect each of the pairs of thin sidewall segments, a direct impact blow on the top cover will transmit the force of such blow directly from the top cover through said connecting portions to the wafers. This top cover also has features configured as nubs, which may engage a floppy disk.  
           [0020]    Generally, all embodiments of the wafer carriers herein will be injection molded of thermoplastic material such as polypropylene. Such material requires structure such as ribs and channels for rigidity.  
           [0021]    In that these shippers do not have the severe particulate control issues that are necessary for carriers in the fab processing environment, it is not necessary to have hermetic sealing. In fact, such hermetic sealing is inimical to robotic handling and easy manual handling, specifically the opening and closing of the shippers. Still, it is important to have the interface between the top cover and the base to provide the best sealing characteristics possible. Moreover, it is important to eliminate or reduce any bowing that occurs along one of the sidewalls intermediate the corners of the top cover or the base.  
           [0022]    These types of containers may be utilized once and thrown away, or may be recycled and utilized multiple times. Although the product shipped in such containers can be of immense value, it is still important to reduce the manufacturing cost of the shippers to as great as extent as possible, consistent with the other necessary characteristics.  
           [0023]    A most important characteristic of such wafer shippers for stackable wafers is that the shippers provide protection from damage due to shock during the transportation. This shock may consist of direct impact with the shipper&#39;s top cover or base, or consist of jarring of the entire shipper package. In either case, it is important to provide protection from damage to the wafers packed therein.  
           [0024]    Moreover, it is important that such wafer shippers provide latching means of high integrity that do not inadvertently open during shipment or handling; for example, when a shipper is inadvertently dropped.  
           [0025]    Such shippers are typically drop tested to determine the overall integrity of the shipper. Upon such dropping, unlatching, breakage of the shipper or damage to the wafers constitutes a failure. The impact during dropping, including drop testing, creates shear, compressive and torsional forces on the shipper components. The shipper, including the latches, must withstand combinations of these forces when loaded.  
           [0026]    These shippers rely heavily upon the separation of materials between wafers or frames, which may be polyethylene sheet material with carbon providing a static dissipative characteristic, polyurethane foam, or other suitable, flexible thin sheet material. Typically, the packing material placed on the bottom and top of the stack will be the polyurethane foam that is compressible. The compressibility of the foam facilitates packing a variable number of wafers in a particular shipper, which can leave some undesirable discretion to the packer as to how many wafers and/or how much padding material is appropriate for a particular shipper. Moreover, inserting excessive, or even a full load, of wafers and foam padding can, in prior art wafer shippers, particularly those with latches on the diagonal corners, cause distortion and/or bowing of the top cover and/or base. This bowing may actually cause a gap between the top cover and base. Such a gap is visually undesirable, may provide a pathway to contamination of the contents, and may further affect the integrity of the container during impact or shock, causing breakage or unlatching.  
           [0027]    If the shipper is underpacked with foam or other packing material, breakage may occur at limits under normal impact limits. Known prior art wafer carriers have provided no ready assistance in identifying an appropriate range of foam and wafer stacked thickness, which is optimal for providing security to the wafers. Similarly, the stacked wafer shippers with the latches on the diagonally opposite corners have provided no means to minimize the visibility of the gap at the sides of the shipper when the shipper is fully loaded or slightly overloaded. Moreover, these prior art shippers have inadequately provided structural means to the base and top cover to provide rigidity and minimize said bowing and gaps at the interface.  
         SUMMARY OF THE INVENTION  
         [0028]    A protective shipper comprises a cover and a base that are held together by a latching member. The base is configurable to retain and protect semiconductor wafers or film frames with wafers within a storage pocket. The base comprises a latching member and a support wall that defines a storage pocket. The cover encloses the storage pocket. One or both of the cover may receive recesses for gripability. The cover may receive one or more latching apertures having a first engagement width and a second engagement width, the first engagement width being larger than the second engagement width. The shipper of the present invention may be manufactured in a mold capable of producing film frame, wafer containing or combination configurations of the shipper by using an interchangeable mold insert.  
           [0029]    A feature and advantage of particular embodiments of the invention is to improve the handling and stacking of shippers by providing recessed portions therein.  
           [0030]    A further feature and advantage of particular embodiments of the invention is that the shipper is less likely to release when shock is introduced because the latches require a horizontal component of movement within the substantially T-shaped aperture to release.  
           [0031]    A further feature and advantage of particular embodiments of the invention is that the shipper can be configured to retain film frames, semiconductor wafers or a combination thereof.  
           [0032]    A further feature and advantage of particular embodiments of the invention is that the shipper can be produced according to film frame, wafer stack or combination configurations on the same machinery.  
           [0033]    A further feature and advantage of particular embodiments of the present invention is to overcome disadvantages present in the prior art.  
           [0034]    Further features and advantages of particular embodiments of the invention will become apparent to those skilled in the art through the descriptions, claims and the figures herein. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0035]    [0035]FIG. 1 is a perspective view of a prior art wafer carrier for carrying a stack of wafers.  
         [0036]    [0036]FIG. 2 is a perspective view of a base of a prior art wafer carrier.  
         [0037]    [0037]FIG. 3 is a perspective view of a top cover of a prior art wafer carrier.  
         [0038]    [0038]FIG. 4 is a perspective view of a prior art wafer carrier illustrating bowing stability issues.  
         [0039]    [0039]FIG. 5 is a perspective view of the portions of two shippers in stacking alignment according to an embodiment of the present invention.  
         [0040]    [0040]FIG. 6 is a perspective view of the base of a wafer shipper according to an embodiment of the present invention.  
         [0041]    [0041]FIG. 7A is a partial plan view of the film frame support wall according to an embodiment of the present invention.  
         [0042]    [0042]FIG. 7B is a partial plan view of the film frame support wall according to an embodiment of the present invention.  
         [0043]    [0043]FIG. 7C is a partial plan view of the film frame support wall according to an embodiment of the present invention.  
         [0044]    [0044]FIG. 7D is a partial plan view of the film frame support wall according to an embodiment of the present invention.  
         [0045]    [0045]FIG. 7E is a partial plan view of the film frame support wall according to an embodiment of the present invention.  
         [0046]    [0046]FIG. 7F is a partial plan view of the film frame support wall according to an embodiment of the present invention.  
         [0047]    [0047]FIG. 7G is a partial plan view of the film frame support wall according to an embodiment of the present invention.  
         [0048]    [0048]FIG. 8 is a plan view of the inside of the top of a cover for a shipper according to an embodiment of the present invention.  
         [0049]    [0049]FIG. 9 is a side view of a cover for a shipper according to an embodiment of the present invention.  
         [0050]    [0050]FIG. 10 is a plan view of the outside top of a cover for a shipper according to an embodiment of the present invention.  
         [0051]    [0051]FIG. 11 is a side view of a cover for a shipper according to an embodiment of the present invention.  
         [0052]    [0052]FIG. 12 is a perspective edge view of a cover for a shipper according to an embodiment of the present invention.  
         [0053]    [0053]FIG. 13 is a top plan view of a base for a shipper according to an embodiment of the present invention.  
         [0054]    [0054]FIG. 14 is a side view of a base for a shipper according to an embodiment of the present invention.  
         [0055]    [0055]FIG. 15 is a bottom view of a base for a shipper according to an embodiment of the present invention.  
         [0056]    [0056]FIG. 16 is a side view of a base for a shipper according to an embodiment of the present invention.  
         [0057]    [0057]FIG. 17 is a perspective edge view of a base for a shipper according to an embodiment of the present invention.  
         [0058]    [0058]FIG. 18 is a diagram of a latching mechanism before introduction of an impact force.  
         [0059]    [0059]FIG. 19 is a diagram of a shipper in shearing movement.  
         [0060]    [0060]FIG. 20 is a diagram of the latching mechanism of FIG. 43 after the shear movement.  
         [0061]    [0061]FIG. 21 is a perspective view of a recess according to an embodiment of the present invention.  
         [0062]    [0062]FIG. 22 is a perspective view of a convertible mold with inserts for converting the mold according to an embodiment of the present invention.  
         [0063]    [0063]FIG. 23 is a perspective view of the latching member of the base according to an embodiment of the present invention.  
         [0064]    [0064]FIG. 24 is a diagram of the latching member engaging the latching aperture according to an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0065]    Copending U.S. Application No. 09/851,499, filed on May 8, 2001, hereby incorporated by reference, discloses a shock resistant variable load tolerant wafer shipper. Such wafer shipper uses axially projecting spring latches to secure said shipper in the closed position.  
         [0066]    Referring to FIGS.  5 - 6 , a shipper for protecting semiconductor wafers or film frames according to embodiments of the present invention is shown. The shipper  100  generally comprises two cooperating portions, configured as a base  102  and a top cover  104 . The top cover  104  and base  102  meet at an interface  106  and are secured by latch mechanisms  108 .  
         [0067]    The base  102  has a plurality of arcuate lateral wafer support segments  110 , which extend from a planar portion  114  of the base and define the wafer stack pocket  112 . A floor  116  is positioned at the bottom of the pocket  112 . The planar portion  114  constitutes a seat and bearing surface for the top cover edge. A side wall  120  extends around the periphery  170  of the base. Nominal wall structures  122  in the pocket floor  116  provide structural rigidity to the base  102 .  
         [0068]    The planar surface  114 , which constitutes a bearing surface for the top cover edge, extends around the lateral wafer support segments  110 . Extending upwardly from the planar surface  114  is a protruding structure configured as a shoulder  128 . The shoulder  128  includes an upright surface  130 , which operates as an outer constraint to the top cover  104 , primarily during impact or other stressing.  
         [0069]    Extending from two of the four corners of the base  102  are latching members  132 . Latching members  132  include a hook portion  134  with a cam surface  136  and an engagement surface  138 . The cam surface  136  deflects the latching member  132  when the top cover  104  is lowered into the latching position and snaps into place with the surface  138  engaged with top surface of the top cover  104 . Significantly, the latching arm  132  has a horizontal extending section  142  and a curved portion  144  extending into an elongated upright portion  146 . The horizontal portion  142  reduces the spring constant of the latching member  132  in the vertical direction by allowing up and down flex of said member  132 . This compares to conventional wafer carriers with latches that do not include said horizontal member that have a spring constant in the vertical direction that equates to the spring constant of the material and any flex in the base where it is attached. This horizontal portion effectively extends the positions where the top cover  102  may be fixed in position. Moreover, it softens the downward pull of the top cover toward the base, which allows greater shock absorption during impact, such as dropping of the shipper. Said shock absorption can prevent further damage to the wafers and prevent damage to the shipper that would otherwise occur.  
         [0070]    Referring to FIGS.  5 , and  8 - 12 , top cover  104  is depicted. The significant features include a nominal wall  140  that comprises the vast majority of said top cover, including various stiffening structure  174 . The nominal wall may be configured to provide a pocket  176  for a 3½ inch diskette or a CD case. The top cover has a periphery  177  that includes an upwardly-extending lip  178  that follows the periphery. Said lip  178  adds to the structural rigidity and provides a stacking means.  
         [0071]    Four planar sidewalls  175  extend downwardly from the upper lip  178  and, along with inset corner portions  173 , define a wafer enclosure. The wafer enclosure perimeter  179  is generally square in shape. At each corner  173  is a flange portion  171  with apertures  148  to receive the latch member  132 . Top cover  104 , in conjunction with the sidewalls  175 , provide a top cover  104  that is highly rigid, even when formed with such soft plastics as polypropylene.  
         [0072]    The latching apertures  148  in cover  104  are formed in an approximate T-shape. This shape comprises a first width or head  150  and a second narrower width or neck  152 . The neck  152  is slightly greater in width than the width of the latching member  132  where it extends through the neck. The head  150  has a width greater than the neck  152 . The latching member  132  engages the head  150  of the aperture  148  and is moved into the neck region  152  due to the movement of cam surface  136  along the underside of the cover  104  corner portion  173  during the latching process.  
         [0073]    Referring to FIGS. 23 and 24, the movement of latching member  132  within the latching aperture  148  is illustrated. The latching aperture has a depth dimensions d 1 , d 2  and d 3  as shown. Dimension d 2  is equal to d 1  plus d 3 . Dimension d 3  is the depth of the engagement surface  138 . Dimension d 1  is the depth of the upright portion  146  of the latching member  132 . The latching member also defines a width dimension w 1 . It should be appreciated that the dimensions of portions of the latching member may vary when measured at different points, due to tapering or irregular shape. Therefore, the dimensions will be described with reference to a maximum value taken at horizontal plane taken at the height of the engagement surface  138 .  
         [0074]    The latching aperture  148  defines a head  150  having a depth dimension a 1  and a neck  152  having a depth dimension a 3 . Dimension a 2  is the sum of a 1  plus a 3 . The head defines a width w 2  and the neck  152  defines a width w 3 . Again, these dimensions are defined as maximum values. Dimension w 2  is greater than w 3  and w 3  is greater than w 1  (w 2 &gt;w 3 &gt;w 1 ). Moreover, a 2  is greater than d 2 , which is greater than a 1  (a 2 &gt;d 2 &gt;a 1 ). Dimension d 3  is also less than a 1  (d 3 &lt;a 1 ) and d 2  is greater than d 3  (d 2 &gt;d 3 ).  
         [0075]    Referring to FIGS. 18, 19 and  20 , an advantage of the approximately T-shaped aperture  148  is illustrated. FIG. 18 shows the latching member  132  in the engaged or latched position. Latching member  132  must receive a purely perpendicular force L to urge said member  132  into the neck region  152  to complete the unlatching process. A force with any non-perpendicular component, such as that received due to a drop or other strike, will not unlatch the cover  104 .  
         [0076]    In FIG. 18, force F is introduced to the shipper. Force F has both a lateral component and a perpendicular component with respect to member  132 . FIG. 19 illustrates how force F causes base  102  to shear in direction M 1  with respect to cover  104 , which moves relatively in direction M 2 . Such relative movements of the cover  104  and base  102  cause latching member  132  to move in direction S, as shown in FIG. 18. By moving to the position shown in FIG. 20, the member  132  cannot move in perpendicular direction L so as to unlatch the shipper  100 . By preventing the shipper  100  from unintentionally unlatching, the protection of the shipper contents is enhanced.  
         [0077]    A further feature of particular embodiments of the invention is shown in the differences between FIG. 5 and FIG. 6. The shipper  100  may be configured to contain either film frames as shown in FIG. 5, or semiconductor wafers as shown in FIG. 6, or a combination thereof. In wafer shipping configuration, the base  102  of shipper  100  is provided with a wafer support wall  120  that defines an inner pocket  154  and an outer region  156 . The support wall  120  in the preferred embodiment is a continuous ring having a diameter only slightly greater than the diameter of the wafers carried therein.  
         [0078]    In film frame configuration, the base of shipper  100  is provided with a frame support wall  158  that defines an inner frame pocket  160  and outside region  162 . The frame support wall  158  preferably forms an undulating surface that alternates between forming an inner circumference  164  and outer circumference  166 , as shown in FIGS. 5 and 6. Other configurations of frame support walls may be used without departing from the scope of the present invention.  
         [0079]    FIGS.  7 A- 7 G show some of the potential alternative wall  160  configurations contemplated by the present invention. As illustrated in FIGS. 7B, 7C and  7 E, the support wall  158  comprises an inner perimeter  165  and outer perimeter  167 . Inner perimeter  165  has a radius r 1  from a center point  194  of the base  102 . Outer perimeter  167  has a radius r 2  from the center point  194 . Dimension r 2  is greater than r 1 . The radius dimensions r 2  and r 1  are varied in a repeating pattern to define the respective outer  165  and inner  167  perimeters.  
         [0080]    A further feature of particular embodiments of the present invention is shown in FIGS.  8 - 17  and  21 . The cover  104  is provided with a plurality of recesses  168  about the perimeter  170 . The recesses  168  are disposed preferably at the approximate midpoint of each side about the perimeter  170  of the cover  104 . However, other configurations of greater or fewer recesses and at other positions are within the scope of the present invention. The base  102  may also be recessed, as shown in FIGS.  16 - 21 , in addition to, or instead of, the recesses in the cover  104 . The recesses  168  enable the carriers  100  to be more easily grasped by either humans or mechanical devices when vertically stacked with one or more respective shippers  100 .  
         [0081]    The top surface of a first shipper is further configured to cooperate with the bottom surface of a second carrier so that the combination of stacked carriers resists shearing movement. FIG. 21 shows base  102  of a first carrier in alignment with a cover  102  of a second carrier. Clearance is created by a recess  168  between the bottom of base  102  of a first shipper and the top of cover  104  of a second shipper in stacked configuration. The recess  168  is formed by an aperture  169  formed in the cover  104  along the periphery thereof. The aperture extends inwardly of at least a portion of the perimeter  179  of the base  102 . A second aperture  196  may also be formed in the perimeter of the base  102 .  
         [0082]    A further feature of particular embodiments of the present invention is shown in FIGS. 5, 6,  16  and  21 . Tab  172  is provided on one or more sides of base  102 . Tab  172  maybe used for mounting an identification and/or information means, such as a bar code label, on shipper  100 . Additionally, the tab, when aligned with recess  168 , serves as a guard for preventing forces from being introduced to the cover  104  of a shipper  100  when the base  102  of said shipper  100  is grasped at recess  168 .  
         [0083]    A further aspect of the present invention is the method for manufacturing a shipper wherein the mold is easily adapted to produce shippers for both wafers and film frames. Referring to FIG. 22, a mold  180  is shown with a lower portion  184  and an upper portion  182  that cooperate to form a mold cavity  186 . Such a mold  180  is shown for molding the base portion having a mold cavity  186 , including a first set of slots  192  or recesses, which are for forming the frame support wall, and a second set of slots  188  or recesses, which are for forming the wafer support wall. Plugs or blanks  190  sized to fill or cover the second set of slots  188  is utilized for converting from, for example, a wafer shipper to a film frame shipper. The methodology of accomplishing comprises insertion of the blanks into the slots and performing the molding operation.  
         [0084]    Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize changes may be made in form and detail without departing from the spirit and scope of the invention.