text: while the making and using of various embodiments of the present invention is discussed in detail below , it should be appreciated that the present invention provides many applicable inventive concepts which can be embodied in a wide variety of specific contexts . the specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention , and do not delimit the scope of the invention . referring to fig1 a lower housing member of a containment device for retaining semiconductor wafers is depicted and generally designated 10 . lower housing member 10 includes a substantially planar frame 12 upon which semiconductor wafers will be placed . extending generally perpendicularly from frame 12 is inner wall 14 . inner wall 14 is sized to closely receive the semiconductor wafers that will be retained within the containment device of the present invention . for example , inner wall 14 may be sized to receive 6 inch , 8 inch , 12 inch or other diameter semiconductor wafers . also extending generally perpendicularly from frame 12 is an outer wall 16 . between inner wall 14 and outer wall 16 is a gap 18 . together outer wall 16 and gap 18 protect the semiconductor wafers from the direct transmission of forces that my contact outer wall 16 during the transportation of semiconductor wafers within the containment device of the present invention . as best seen in fig2 a pair of latches 20 extend generally perpendicularly from frame 12 . each of the latches 20 includes a hook 22 that will securably attach lower housing member 10 to an upper housing member as will be more fully discussed with reference to fig5 . referring now to fig1 and 3 , outer wall 16 includes a pair of oppositely disposed slots 24 . similarly , inner wall 14 has a pair of oppositely disposed slots 26 . together , slots 24 and slots 26 allow for the automated loading and unloading of semiconductor wafers using a typical wafer loading arm . in addition , inner wall 14 includes a pair of oppositely disposed notches 28 that are used to determine the maximum height for stacking semiconductor wafers within lower housing member 10 of the containment device of the present invention . referring now to fig4 a top view of lower housing member 10 is depicted . frame 12 of lower housing member 10 includes a plurality of reinforcement members including ribs 30 and rings 32 . as best seen in fig3 rings 32 , as well as ribs 30 , extend outwardly from the bottom surface of frame 12 and prevent the flexure of frame 12 during , for example , loading , unloading and transporting semiconductor wafers within the containment device of the present invention . additionally , frame 12 includes an outer lip 34 that will mesh with an outer lip of an upper housing member of the containment device of the present invention as will be more fully explained with reference to fig5 . lower housing member 10 may be constructed from any suitably rigid material that provides support and containment for the semiconductor wafers to be disposed therein . for example , lower housing member 12 may be constructed from a plastic such as polypropylene . in addition , it has been found that the use of a conductive material will minimize the buildup of static charge on the semiconductor wafers disposed within lower housing member 10 . for example , a carbon impregnated polypropylene is suitable for discharging such static buildup . referring now to fig5 a top view of the upper housing member is depicted and generally designated 36 . upper housing member 36 includes a frame 38 that is generally planar . frame 38 includes a pair of oppositely disposed holes that are designed to receive hooks 22 of latches 20 of lower housing member 10 . in operation , latches 20 are hingably attached to lower housing member 10 such that hooks 22 may be radially deflected outward as the inner surface of holes 40 come in contact with the angled surface of hooks 22 as best seen in fig2 . when hooks 22 extend above holes 40 , latches 20 snap radially inwardly so that hooks 22 overlap the inner edge of holes 40 such that lower housing member 10 and upper housing member 36 are securably attached together . frame 38 of upper housing member 36 includes an outer lip 42 . outer lip 42 is sized such that it may be closely received within outer lip 34 of lower housing member 10 as best seen in fig3 . as such , similarly designed containment devices may be stacked together in a secure manner thereby preventing potential damage to the semiconductor wafers stored therein as the containment devices of the present invention are transported from one location to another . as best seen in fig6 frame 38 includes a series of reinforcement members in the form of concentric rings such as ring 44 . the reinforcement members minimize the flexure of upper housing member 36 such that when upper housing member 36 and lower housing member 10 are securably attached together , protection is provided for the semiconductor wafers disposed therein . inwardly extending from frame 38 is a spacer 46 that contacts the upper surface of the semiconductor wafers stacked within the containment device of the present invention . spacer 46 minimizes the axial movement of the semiconductor wafers within the containment device of the present invention during the transportation of the semiconductor wafers . referring now to fig7 a bottom view of upper housing member 36 is depicted . upper housing member 36 has a wall 48 that extends generally perpendicularly to frame 38 . wall 48 is sized such that when upper housing member 36 is securably attached to lower housing member 10 , wall 48 is exteriorly disposed about outer wall 16 of lower housing member 10 . upper housing member 36 also has a pair of oppositely disposed walls 50 that have a planar surface , as best seen in fig7 and 8 . walls 50 allow adjacent containment devices of the present invention to be packed tightly together in , for example , a shipping box or pallet . additionally , upper housing member 36 has a pair of oppositely disposed planar walls 52 that provide for tight packing of adjacent containment devices as best seen in fig9 . referring now to fig1 , a cross sectional view of lower housing member 10 loaded with a plurality of semiconductor wafers 54 is depicted . prior to loading lower housing member 10 with semiconductor wafers 54 , a cushion 56 is placed on the upper surface of frame 12 . cushion 56 provides protection to semiconductor wafers 54 from external shock . cushion 56 may be constructed from an anti - static foam such that static charge will not develop between cushion 56 and a semiconductor wafer 54 . on top of cushion 56 is a wafer separator 58 . wafer separator 58 is constructed from a conductive material having low ionic contamination and minimal loose particles . for example , wafer separator 58 may be constructed from a carbon impregnated polyethylene . the ionic contamination of wafer separator 58 should not exceed 20 ng / cm 2 of fluoride ions , chloride ions or sodium ions , should not exceed 30 ng / cm 2 of potassium ions or ammonium ions and should not exceed 40 ng / cm 2 of bromide ions , phosphate ions , nitride ions or sulfate ions . additionally , wafer separator 58 should not have more than 100 , 000 loose particles per cubic foot that exceed 0 . 5 micrometers . on top of wafer separator 58 is a semiconductor wafer 54 . thereafter , a plurality of wafer separators 58 and semiconductor wafers 54 may be stacked in sequence . on top of the last semiconductor wafer 54 there is a wafer separator 58 . on top of the last wafer separator 58 is an additional cushion 56 that also protects semiconductor wafers 54 from impacts . referring now to fig1 and 12 there is shown a second form in accordance with the first embodiment of the invention wherein all elements are identical to the first embodiment except that four latches 20 , each with a hook 22 , are provided , one latch at each corner of the lower housing and the upper housing includes four holes 40 for receiving the latches 20 and hooks 22 . the operation is otherwise the same as in the first form of the first embodiment . referring to fig1 to 17 , there is shown a second embodiment in accordance with the present invention . in accordance with the second embodiment of the invention , the outer wall is not provided and , instead , the remaining wall 60 , which corresponds to the inner wall of the first embodiments , is lined with a very soft rubber or foam or the like 62 , preferably of an antistatic variety , such as pink polyethylene antistatic foam , which will absorb shock applied to the housing as shown in fig1 and 16 . this embodiment provides added shock protection and becomes more useful as the diameters of the wafers increase and / or as the thicknesses of the wafers decrease . in accordance with this embodiment , the latches 20 with hooks 22 thereon and the holes 40 for receiving the latches are replaced , the latches being replaced by flaps 64 with hooks 66 at the distal end of each flap and the holes 40 are replaced with a recess 68 in the upper housing for receiving the hooks . the latches 64 are secured to the lower housing , preferably at the bottom of the lower housing as shown and are rotatable about a thinned or scored region 70 so that the latch can be rotated with the hook 66 travelling over the upper housing portion and into the recess 68 in the upper housing portion to provide the locking action and retain the upper and lower housing portions together . the latches 64 are preferably molded along with the lower housing as a single unit with the thin region or score region 70 provided as a part of the molding operation . the upper and lower housings are preferably polypropylene . the upper housing portion contains a downwardly depending member 72 at its inner surface which will impinge against the protective material disposed between the member 72 and the uppermost wafer to provide a minimal force which prevents the wafers from movement within the housing . the housing in accordance with the second embodiment is loaded in the same manner as described above with reference to the first embodiment and the materials for the housing portions are the same as described above with reference to the first embodiment . the upper and lower housing members are shown in assembled state in fig1 with like character references depicting the same structures as in the first embodiments . while this invention has been described with a reference to illustrative embodiments , this description is not intended to be construed in a limiting sense . various modifications and combinations of the illustrative embodiments as well as other embodiments of the invention , will be apparent to persons skilled in the art upon reference to the description . it is , therefore , intended that the appended claims encompass any such modifications or embodiments .