Abstract:
A wafer container suitable for the storage and/or transport of multiple IC wafers. The container includes a wafer holder provided with multiple, upward-standing sidewalls, at least one of which is removable to enable horizontal as well as vertical removal of the IC wafers from the wafer holder and prevent collisions which may otherwise occur between the wafer being removed and the sidewalls. The inner, wafer-engaging surface of each of the sidewalls may include a flexible material or pad for preventing scratching and/or chipping of the wafers during wafer storage, transport and/or removal.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to containers used in the packaging of semiconductor wafers for transport or shipping. More particularly, the present invention relates to a new and improved wafer container having a removable sidewall or sidewalls which facilitate(s) horizontal removal of wafers from the container to prevent damage to the wafers.  
         BACKGROUND OF THE INVENTION  
         [0002]    In the semiconductor production industry, various processing steps are used to fabricate integrated circuits on a semiconductor wafer. These steps include the deposition of layers of different materials including metallization layers, passivation layers and insulation layers on the wafer substrate, as well as photoresist stripping and sidewall passivation polymer layer removal. In modern memory devices, for example, multiple layers of metal conductors are required for providing a multi-layer metal interconnection structure in defining a circuit on the wafer. Chemical vapor deposition (CVD) processes are widely used to form layers of materials on a semiconductor wafer. Other processing steps in the fabrication of the circuits include formation of a photoresist or other mask such as titanium oxide or silicon oxide, in the form of the desired metal interconnection pattern, using standard lithographic techniques; subjecting the wafer substrate to a dry etching process to remove the conducting layer from the areas not covered by the mask, thereby leaving the metal layer in the form of the masked pattern; removing the mask layer using reactive plasma and chlorine gas, thereby exposing the top surface of the metal interconnect layer; cooling and drying the wafer substrate by applying water and nitrogen gas to the wafer substrate; and removing or stripping polymer residues from the wafer substrate.  
           [0003]    After the devices are fabricated on the wafer surface, the wafers are packaged and transported to a separate facility which is remote from the fabrication facility for separation of the wafers into individual chips. The integrated circuits on the wafer are prone to damage due to mechanical shock during transit from the fabrication facility to the packaging or other facility. In addition to mechanical shock, integrated circuits are susceptible to damage by electrostatic discharges (ESD) and electrical overstress (EOS). As USLI technology continues downscaling of device features, the wafer size becomes correspondingly larger for economical production of the integrated circuits. Accordingly, the wafers become increasingly expensive with increased size. For example, the cost of a  12 ′ wafer is about 2.5 times the cost of an  8 ′ wafer. One production lot (25 wafers) of  8 ′ wafers costs about $40,000. Thus, protection of the wafers during shipping is of utmost importance. Clearly, suppliers of semiconductor wafers would, if possible, like to avoid or reduce as much as possible the potential wafer damage, inconvenience and quality control issues which are associated with traditional methods of packaging wafers for transport.  
           [0004]    Transport and storage of semiconductor wafers has presented problems as the diameter of wafers has increased in size and the circuitry on the wafers has become increasingly miniaturized. Containers for storing and transporting IC wafers are described in U.S. Pat. Nos. 4,787,508 and 5,366,079. While the disclosed containers are major improvements over other known containers, in certain situations, damage can still occur. The large-diameter wafers (8 or 12 inches in diameter) are the most vulnerable to damage. Any movement of or stress on the wafers in the container could potentially damage the very fragile circuit patterns on the surface of the wafers and/or crack the wafers.  
           [0005]    U.S. Pat. No. 5,366,079 discloses a container and retainer combination that effectively reduces damage due to shifting of the wafers in the container. However, the storage and handling of very large diameter wafers still presents problems due to the flexing of the large diameter containers when they are opened and otherwise manipulated, resulting in fractured and broken wafers.  
           [0006]    A typical conventional IC (integrated circuit) wafer container, such as that disclosed in U.S. Pat. No. 5,699,916, is shown in FIGS. 1 and 2. The wafer container  8  includes a wafer holder  12  including a base  14  with a stepped wafer support surface  16  thereon. Multiple, curved or arcuate wafer panels  18  extend upwardly from the wafer support surface  16 , defining a vertical slot  20  between adjacent wafer panels  18 . As shown in FIG. 2, multiple semiconductor wafers  22  are stacked on the wafer support surface  16  and on each other. An enclosure  10  fits over the upward-standing wafer panels  18  and the wafer support surface  16  and engages the base  14  to enclose the stacked wafers  22 .  
           [0007]    Removal or unpacking of the individual wafers  22  from the wafer holder  12  is effected by extending an elongated vacuum pin  24 , terminated by a vacuum head  25 , through one of the slots  20  and then applying the vacuum head  25  to the upper surface of the uppermost wafer  22  such that vacuum pressure holds the wafer  22  against the vacuum head  25 . Next, the vacuum pin  24  and attached wafer  22  are lifted, as indicated by the arrows, until the wafer  22  being removed clears the height of the wafer panels  18 . The wafer  22  is then moved horizontally over the wafer panels  18  and placed in a separate location.  
           [0008]    One of the problems commonly encountered during unpacking of the wafers  22  from the wafer holder  12  is that the delicate wafers  22 , horizontal movement of which is constrained by the fixed wafer panels  18 , may be damaged in the event that the wafers  22  inadvertently collide with the wafer panels  18  during removal. For that reason, much care must be taken to minimize horizontal movement of the vacuum pin  24  and the wafer  22  being removed to prevent collision of the wafer  22  with the wafer panels  18 . Consequently, unloading of all of the wafers  22  from the wafer holder  12  may require an inordinately long period of time, reducing the operational efficiency of the unpacking procedure. Accordingly, a wafer container is needed which facilitates removal or unpacking of wafers in an efficient and safe manner.  
           [0009]    An object of the present invention is to provide a new and improved wafer container suitable for IC (integrated circuit) wafers.  
           [0010]    Another object of the present invention is to provide a new and improved wafer container suitable for storing and/or transporting IC wafers, which container facilitates the efficient and safe removal of IC wafers from the container.  
           [0011]    Still another object of the present invention is to provide a new and improved wafer container which enables horizontal as well as vertical removal of IC wafers from the container.  
           [0012]    Yet another object of the present invention is to provide a new and improved wafer container which prevents cracking, chipping or other damage to IC wafers as the wafers are unpacked or removed from the container.  
           [0013]    A still further object of the present invention is to provide a new and improved wafer container which includes a wafer holder having multiple, upward-standing sidewalls, at least one of which may be removed to enable horizontal removal of IC wafers from the container.  
           [0014]    Yet another object of the present invention is to provide a new and improved wafer container including a wafer holder having multiple, upward-standing sidewalls, the inner surface of which sidewalls may be fitted or coated with a soft flexible material or pad to prevent scratching of the wafers during wafer storage, transport and/or removal.  
         SUMMARY OF THE INVENTION  
         [0015]    In accordance with these and other objects and advantages, the present invention is generally directed to a wafer container suitable for the storage and/or transport of multiple IC wafers. The container includes a wafer holder provided with multiple, upward-standing sidewalls, at least one of which is removable to enable horizontal as well as vertical removal of the IC wafers from the wafer holder and prevent collisions which may otherwise occur between the wafer being removed and the sidewalls. The inner, wafer-engaging surface of each of the sidewalls may include a flexible material or pad for preventing scratching and/or chipping of the wafers during wafer storage, transport and/or removal.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    The invention will better understood, by way of example, with reference to the accompanying drawings, in which:  
         [0017]    [0017]FIG. 1 is a perspective view, partially in section, of a typical conventional IC wafer container;  
         [0018]    [0018]FIG. 2 is a perspective view of a wafer holder portion of a conventional IC wafer container;  
         [0019]    [0019]FIG. 3 is an exploded, perspective view, partially in section, of an IC wafer container with removable sidewalls of the present invention;  
         [0020]    [0020]FIG. 4 is a front view of the IC wafer container of the present invention;  
         [0021]    [0021]FIG. 5 is a sectional view, taken along section lines  5 - 5  in FIG. 4;  
         [0022]    [0022]FIG. 6 is a front view of another embodiment of the IC wafer container of the present invention;  
         [0023]    [0023]FIG. 7 is a sectional view, taken along section lines  7 - 7  in FIG. 6;  
         [0024]    [0024]FIG. 8 is a front view of the IC wafer container of the present invention, loaded with IC wafers, with the enclosure portion of the container shown in phantom;  
         [0025]    [0025]FIG. 9 is a front view of the IC wafer container of the present invention, more particularly illustrating removal of wafers from the container in implementation of the present invention; and  
         [0026]    [0026]FIG. 10 is a top view of the IC wafer container, illustrating removal of wafers from the container in implementation of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0027]    The present invention has particularly beneficial utility in the storage, transport, and/or shipping of multiple IC semiconductor wafers and facilitating safe and efficient removal or unpacking of the wafers. However, the invention is not so limited in application, and while references may be made to such IC wafers, the present invention is more generally applicable to storing, transporting and/or shipping delicate items or substrates and facilitating safe and efficient removal or unpacking of the items or substrates after storage, transportation and/or shipping.  
         [0028]    Referring initially to FIGS.  3 - 7 , an illustrative embodiment of the IC wafer container of the present invention is generally indicated by reference numeral  28 . Preferably, through not necessarily, the components of the IC wafer container  28  hereinafter described are constructed of a clear or translucent material. The IC wafer container  28  includes a wafer holder  32 , on which is removably fitted an enclosure  30  having an enclosure top  31  from which downwardly extends a cylindrical enclosure wall  33  that defines an enclosure interior  35 . An annular flange  33   a  may be shaped in the interior surface of the enclosure wall  33  at the bottom end thereof. The wafer holder  32  includes a typically circular base  34  from which extends a stepped wafer support surface  36 . The wafer support surface  36  may be provided with a circumferential base groove  34   a  which removably receives the flange  33   a  of the enclosure wall  33  in a snap-fit, as hereinafter further described. A pair of fixed sidewalls  38 , each typically having a generally arcuate or curved cross-section, extends upwardly from the wafer support surface  36  and is fixedly attached to the wafer support surface  36 . The typically concave inside surface of each fixed sidewall  38  may be provided with a flexible cushion or pad  49  which may be constructed of foam or other soft, pliant material, the purpose of which cushion or pad  49  will be hereinafter described. As shown in FIG. 3, in one embodiment at least one, and typically, a pair of sidewall grooves  47 , each matching the contour of each of the removable sidewalls  39 , is provided in the wafer support surface  36  in opposing relationship to the fixed sidewalls  38 . At least one, and typically, a pair of removable sidewalls  39  is removably attached to the wafer support surface  36  typically by friction-fitting the lower end portion  39   a  of each removable sidewall  39  in the corresponding sidewall groove  47 , as shown in FIGS. 3 and 5. In another embodiment of the invention, shown in FIGS. 6 and 7, a pair of parallel, typically arcuate sidewall flanges  61 , which may be connected at each end by a flange connector  62 , extends upwardly from the wafer support surface  36  in place of the sidewall grooves  47  heretofore described with respect to FIG. 3. Accordingly, the bottom end portion  39   a  of each removable sidewall  39  is removably friction-fitted between the corresponding pair of sidewall flanges  61  to removably mount the removable sidewalls  39  on the wafer support surface  36 . Like that of the fixed sidewalls  38 , the typically concave interior face of each removable sidewall  39  may be provided with a flexible cushion or pad  49  which may be constructed of foam or other soft, pliant material. A sidewall space  40  is defined between adjacent ones of the fixed sidewalls  38  and the removable sidewalls  39 .  
         [0029]    Referring again to FIG. 3 and to FIG. 8, the IC wafer container  28  is a suitable vehicle for the storage, transport and/or shipping of multiple IC wafers  42 . Accordingly, the IC wafers  42  are stacked on top of each other on the wafer support surface  36  inside the upward-standing fixed sidewalls  38  and removable sidewalls  39 , as shown in FIG. 8. A sheet of lint-free paper  43  may be interposed between every two of the stacked IC wafers  42 . It will be appreciated by those skilled in the art that the pads  49  on the interior concave surfaces of the fixed sidewalls  38  and removable sidewalls  39 , respectively, prevent scratching or other damage to the IC wafers  42  as the edges of the IC wafers  42  inadvertently contact the pads  49  during loading or transport of the IC wafers  42 . After the IC wafers  42  are loaded in stacked form into the wafer holder  32 , a wafer spring or retainer  64 , constructed of a flexible, resilient material and having a central portion  65  from which outwardly extends multiple retainer arms  66 , is placed on the upper one of the stacked IC wafers  42  or on a sheet of paper  43  placed on the uppermost one of the IC wafers  42 . Finally, the enclosure  30  is lowered in place over the wafer holder  32  until the flange  33   a  on the lower interior of the enclosure wall  33  removably snaps into the circumferential base groove  34   a  of the base  34 . Accordingly, the wafer retainer  64  is interposed between the bottom, interior surface of the enclosure top  31  and the upper one of the IC wafers  42  and functions as a shock-absorbing spring during handling and transport of the IC wafer container  28  during storage, transport and/or shipping of the IC wafers  42  contained therein.  
         [0030]    Referring next to FIGS. 9 and 10, the multiple wafers  42  are removed from the IC wafer container  28  as follows. First, the enclosure  30  is raised from the wafer holder  32  after the flange  33   a  (FIG. 3) is disengaged from the base groove  34   a  of the wafer holder  32 . Next, the removable sidewalls  39  are removed from the wafer support surface  36  by disengaging the lower end  39   a  of each removable sidewall  39  from the corresponding sidewall groove  47  (FIG. 5) or from the corresponding pair of adjacent sidewall flanges  61  (FIG. 7). The uppermost IC wafer  42  is then removed from the wafer holder  32  by applying the vacuum head  45  of a vacuum pin  44  to the upper surface of the uppermost IC wafer  42  in the manner shown in FIG. 9. Accordingly, the IC wafer  42  adheres to the bottom surface of the vacuum head  45  by vacuum suction pressure in such a manner that the IC wafer  42  can be lifted from the underlying IC wafer  45  by lifting upwardly on the vacuum pin  44 . As shown in FIG. 10, in a preferred embodiment a wafer removal opening  41  is defined between a wall end  38   a  of one of the fixed sidewalls  38  and the wall end  38   b  of the adjacent fixed sidewall  38 . The straight-line width of the wafer removal opening  41  is greater than the diameter of each IC wafer  42 . Accordingly, it will be appreciated from a consideration of FIG. 9 that each IC wafer  42  can be moved in both the horizontal direction  71  as well as the vertical direction  70 , through the wafer removal opening  41 , during removal of the IC wafer  42  from the wafer holder  32 , without causing the IC wafer  42  to inadvertently strike one of the remaining upward-standing fixed sidewalls  38 . After the uppermost IC wafer  42  is removed from the wafer holder  32  in the foregoing manner, the remaining underlying IC wafers  42  are removed from the wafer holder  32  in like manner. Finally, the removable sidewalls  39  are replaced on the wafer holder  32  preparatory to loading a second lot of the IC wafers  42  therein for storage, transport and/or shipping as heretofore described.  
         [0031]    While the preferred embodiment of the invention heretofore described includes a pair of fixed sidewalls  38  and a pair of removable sidewalls  39 , it is understood that all of the sidewalls may be removable. Furthermore, any number of the fixed sidewalls  38  may be provided in combination with any number of the removable sidewalls  39 , as long as removal of the removable sidewalls  39  defines a wafer removal opening  41  of sufficient width to facilitate removal of the wafers  42  from the wafer holder  32  along a generally horizontal plane.  
         [0032]    While the preferred embodiments of the invention have been described above, it will be recognized and understood that various modifications can be made in the invention and the appended claims are intended to cover all such modifications which may fall within the spirit and scope of the invention.