Abstract:
A tool and method for assessing whether a disk carrier, and especially a carrier for holding semiconductor disks, is properly dimensioned. The tool has a body that includes a socket in which a portion of the disk carrier will seat fully if the disk carrier is properly dimensioned. Alignment structures may be provided in the socket to align with features of the carrier to assist in determining whether the disk carrier is properly dimensioned. The socket may include two spaced apart cavities that correspond with end portions of walls of the disk carrier.

Description:
FIELD OF INVENTION  
       [0001]     This invention relates generally to semiconductor manufacturing equipment and more particularly to an apparatus and method for checking the dimensions of a wafer carrier.  
       BACKGROUND  
       [0002]     Wafer or disk carriers are used with semiconductor manufacturing equipment such as wafer handlers to store and transport semiconductor wafers in processes for making semiconductor devices such as integrated circuits. A common design for such wafer carriers stacks a plurality of the wafers in close proximity to each other, with each wafer having its own slot within the carrier. It is important that the wafers be precisely spaced and aligned within the carrier so that when the carrier is in use, the wafer handlers are properly aligned with the individual wafers. Misaligned wafers can result in damage to the tooling, breakage of the wafers or improperly etched wafers.  
         [0003]     It can be difficult to determine from a visual inspection whether a carrier is properly dimensioned. Through repeated use, or trauma, a carrier can lose its proper shape. Additionally, new carriers often do not match specifications. As a result, users commonly rely on “known good” carriers that have been used successfully in the past, which can result in moving wafers from loaded carriers that are of unknown quality to known good carriers. Such changing of carriers can increase the contamination of the wafers, and may even result in additional broken wafers.  
         [0004]     What is needed is a device to easily and quickly verify whether a disk carrier complies with the desired size and shape specifications. Preferably the device is simple and economical to use and construct.  
       SUMMARY OF THE INVENTION  
       [0005]     According to one embodiment, the present invention provides an apparatus for use with a disk carrier of the type that has spaced-apart first and second side walls with respective first and second end portions spaced apart by a distance and defining an opening having respective slots for receiving and stacking a plurality of semiconductor wafers within the carrier during a semiconductor manufacturing process. The apparatus includes a body that has a first structure for forming a first cavity adapted to confine the first end portion of the carrier on the body and a second structure for forming a second cavity adapted to confine the second end portion of the carrier on the body. The first and second cavities are spaced apart a distance equal to the distance between the first and second end portions of the carrier. The carrier is properly dimensioned when the first and second end portions of the carrier fully seat within the first and second cavities of the body.  
         [0006]     According to another embodiment, the present invention provides an apparatus for determining whether a size and shape of a portion of a disk carrier used in a semiconductor manufacturing process is properly dimensioned. The apparatus comprises a body provided with a socket having a reciprocal size and shape adapted to receive a portion of a disk carrier. If the portion is properly dimensioned the portion seats fully within the socket and if the portion is not properly dimensioned the portion will not seat fully into the socket.  
         [0007]     According to yet another embodiment, the invention provides a method of assessing a portion of a disk carrier. An apparatus is provided that has at least one cavity of a desired size and shape to receive the portion of the disk carrier. An attempt is made to insert a portion of the disk carrier into the cavity, and then a determination is made as to whether the disk carrier conforms to the desired configuration depending on whether the portion fits into the cavity. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1  is a perspective view showing a disk carrier checker according to the present invention with a disk carrier mounted thereon.  
         [0009]      FIG. 2  is a perspective view of the disk carrier of  FIG. 1 .  
         [0010]      FIG. 3  is a top plan view of the disk carrier checker of  FIG. 1 .  
         [0011]      FIG. 4  is a cross-sectional view of the disk carrier checker of  FIG. 1  taken along the line  4 - 4  of  FIG. 3 , showing in phantom lines a portion of a conforming disk carrier fully seated within the checker.  
         [0012]      FIG. 5  is a cross-section view of the disk carrier checker of  FIG. 1  taken along line  4 - 4  of  FIG. 3 , showing in phantom lines a portion of a nonconforming disk carrier that will not fully seat within the checker.  
         [0013]      FIG. 6  is a cross sectional view of the disk carrier checker of  FIG. 1  taken along the line  6 - 6  of  FIG. 4  showing a portion of a conforming disk carrier with the disk slot alignment protrusions registering with corresponding disk slots of the conforming disk carrier.  
         [0014]      FIG. 7  is a cross sectional view of the disk carrier checker of  FIG. 1  taken along the line  6 - 6  of  FIG. 4  showing a portion of a nonconforming disk carrier with the disk slot alignment protrusions interfering with corresponding disk slots of the nonconforming disk carrier.  
         [0015]      FIG. 8  is a perspective view showing the disk carrier of  FIG. 1  being inserted into the disk carrier checker of  FIG. 1  to determine if the disk carrier is properly dimensioned.  
         [0016]      FIG. 9  is a partial perspective view of the disk carrier and disk carrier checker of  FIG. 1  after the disk carrier has been fully inserted into the disk carrier checker, for example in accordance with  FIG. 8 .  
         [0017]      FIG. 10  is an enlarged partial perspective view showing the disk carrier checker and disk carrier of  FIG. 1 , where the disk carrier is a conforming disk carrier fully seated in the checker, for example in accordance with  FIG. 8 .  
         [0018]      FIG. 11  is an enlarged partial perspective view showing the disk carrier checker and disk carrier of  FIG. 1 , where the disk carrier is a nonconforming disk carrier that is not fully seated in the checker, for example in accordance with  FIG. 8 . 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0019]     Apparatus or disk carrier checker  101  of the present invention is used to determine whether a disk carrier  102  conforms to a desired size and shape. As seen in  FIG. 1 , according to one embodiment of the present invention, the disk carrier checker  101  has a generally flat base  103  that includes a socket into which a carrier  102  that conforms to the desired size and shape will seat flatly. Thus, the carrier checker  101  acts as a tool to assess a disk carrier  102 , or at least a portion of the disk carrier  102 , for compliance with a specified size and shape. Disk carriers  102  that conform to the desired shape and size are identified as “good” or “conforming” disk carriers  102 . Disk carriers  102  that do not conform to the desired shape and size are identified as “bad” or “nonconforming” disk carriers  102 . The features and operation of the checker  101  are described in detail below.  
         [0020]     The carrier  102  includes facing spaced-apart first and second side walls  107 . Parallel first and second slots  108  are formed in the respective first and second side walls  107  to retain disks (not shown) within the carrier  102  in a stacked arrangement. The carrier  102  shown in the drawings is suited to hold about twenty-five (25) disks; however, the exact capacity and design of the carrier  102  is not crucial to the workings of the present invention. As shown in  FIG. 2 , the first and second end portions  125  and  126  of the first and second side walls  107  are capped by respective first and second feet  104  and  109 . In the embodiment shown, each foot  104  and  109  is a generally flat plate that is substantially perpendicular to the respective side wall  107  to which it is affixed. The feet  104  and  109  may include a pin  110  or similar projecting structure protruding from their bottom surface. Similarly, an aperture  111 , or other opening, bore or passageway, may be provided on one or more of the feet  104  and  109 . Pins  110  and apertures  111  are common to such carriers  102  and may be used to align two carriers  102  in a facing relation to transfer disks between the two carriers  102 .  
         [0021]     One preferred embodiment of the apparatus or checker  101  includes a base  103  having an upper surface  112 , as illustrated in  FIGS. 1 and 3 . Cavities or pockets  105  and  106  provided on the upper surface  112  have a reciprocal shape that corresponds with a desired shape and size for the feet  104  and  109  of the carrier  102 . The pockets  105  and  106  can be formed, as shown in  FIG. 3 , by facing surfaces or walls or rails, or similar members, mounted to the upper surface  112  of the base  103 . For example, the first pocket  105  can be formed by a first outer side rail  113 , a first inner side rail  114 , a top rail  115  and a bottom rail  116 . Similarly, the second pocket  106  can be formed by facing surfaces of a second outer side rail  117 , a second inner side rail  118 , the top rail  115 , and the bottom rail  116 . A first seating pad  119  and a second seating pad  120  may be provided on surface  112  of base  103  to form the bottom surfaces of the pockets.  
         [0022]     The base  103  is a relatively rigid substrate with a generally flat upper surface  112 . Preferably the base  103  is durable and difficult to deform, so that it retains its shape. Preferred materials for the base include a sheet of hard plastic, metal, or composite material. The overall outer shape of the base  103  is not critical; however, it is preferred to leave some amount of border around the rails  113 ,  115 ,  116 , and  117  in order to facilitate handling of the tool  101 . Preferably the base  103  will be relatively resistant to expansion and contraction in response to temperature changes.  
         [0023]     The rails  113 ,  114 ,  115 ,  116 ,  117 , and  118  are elongated bars that have side surfaces that extend perpendicularly from the upper surface  112  of the base  103  to form the pockets  105  and  106 . The overall cross-section of the rails are not critical, provided that the side surfaces that form the pockets  105  and  106  are generally perpendicular to the upper surface  112  of the base  103 . Elongated bars with a rectangular cross-section are preferred because they are easy to work with. It should be appreciated that each rail  113 ,  114 ,  115 ,  116 ,  117 , and  118  could include more than one segment or piece of material. The rails  113 ,  114 ,  115 ,  116 ,  117 , and  118  are also preferably made from a rigid durable material such as hard plastic, metal, or composite material. Those of skill in the art will be aware of numerous suitable materials. The rails  113 ,  114 ,  115 ,  116 ,  117 , and  118  are fixed to the upper surface  112  of the base  103  by any suitable means such as bolts or other fasteners (not shown) through the bottom of the base  103  that extend into the rails. Other standard fastening mechanisms such as adhesives, welding, screws and the like would also be suitable. Alternatively, the entire structure of the checker  101 , including the base  103  and the rails  113 ,  114 ,  115 ,  116 ,  117 , and  118 , can be injection molded or otherwise formed as a single unitary piece.  
         [0024]     Seating pads  119  and  120  provide a flat bottom surface for the pockets  105  and  106  respectively. In the embodiment shown, the first seating pad  119  is provided with a pair of alignment protrusions  121  for mating engagement with alignment apertures  111  on the first foot  104 . In some instances it may be preferable to omit the alignment protrusions  121 , because they can make seating of the foot  104  in pocket  105  more cumbersome. The second seating pad  120  is provided with a pair of alignment passages or bores  122  for mating engagement with the alignment pins  110  on the second foot  109 . The seating pads  119  and  120  are similar in form to the rails, but have a lower profile and can have any suitable cross-sectional shape. The top surfaces of the seating pads  119  and  120  are preferably flat, to provide a resting surface for the substantially planar bottom of the feet  104  and  109 . It is appreciated that the top surfaces of the seating pad can be contoured to conform to the bottom of feet  104  and  109  where the bottom of the feet is not planar.  
         [0025]     Slot alignment protrusions  123  are provided in the pockets  105  and  106  to engage slots  108  of the carrier  102 . The slot alignment protrusions  123  are provided at the junctions of the inner side rails  114  and  118  and the seating pads  119  and  120 . The slot alignment protrusions  123  may be formed as part of the pads  119  and  120  or as part of the inner side rails  114  and  118 . Alternatively, the slot alignment protrusions  123  may be separate pieces that are fastened to either or both of the inner side rail and the seating pad. Though not required, the slot alignment protrusions  123  are provided in pairs such that in each pair of slot alignment protrusions  123  engages with or extends into corresponding ends of the associated slot  108 . It should be understood that a single slot  108  may in fact be formed by two corresponding facing pockets formed in the first and second sidewalls  107 . For example a first pair of slot alignment protrusions  123  engages with corresponding ends of the first slot, a second pair of slot alignment protrusions  123  engages with the fifteenth slot, and a third pair of slot alignment protrusions  123  engages with the twenty-fifth slot. The slot alignment protrusions  123  are sized to a close tolerance with the slots  108 , that is the protrusions have a transverse dimension that closely approximates the width of the slots, so that that slot alignment protrusions  123  will interfere with seating of the feet  104  or  109  within the pockets  105  and  106  if the protrusion  123  is not closely aligned with its corresponding slot  108 .  
         [0026]      FIG. 4  shows the first and second pockets  105  and  106  in cross-section. The position of a carrier  102  that conforms to the desired dimensions is illustrated in phantom lines. As can be seen, the width of the pockets  105  and  106  closely matches the width of the feet  104  and  109  so that if the feet  104  and  109  do not closely match the desired specifications, and as such are not properly dimensioned, the feet  104  and  109  will not slide easily into the pockets  105  and  106 . In the circumstance of a conforming carrier  102 , as illustrated in  FIG. 4 , the bottoms of the feet  104  and  109  seat flush against the top surface of the seating pads  119  and  120 . The alignment protrusion  121  in first pocket  105  is matingly received into the alignment aperture  111  in the first foot  104 . Similarly, the alignment passage  122  in the seating pad  120  of the second pocket  106  matingly receives the alignment pin  110  of the second foot  109 .  
         [0027]      FIG. 5  is the same view as  FIG. 4 , except that a non-conforming carrier  102  is shown in phantom lines. In the instance of a non-conforming carrier  102 , the feet  104  and  109  do not seat flat or flush against the pads  119  and  120 . The interference that prevents the feet  104  and  109  from completely seating can result from one or more of the rails  113 ,  114 ,  115 ,  116 ,  117 , or  118 , the alignment protrusion  121 , the alignment passage  122 , or the slot alignment protrusions  123  engaging the improperly dimensioned carrier  102  and thus precluding flush seating of the feet  104  and  109  with respective pads  119  and  120  within respective pockets  105  and  106 .  
         [0028]      FIGS. 6 and 7  show the slot alignment protrusions  123  in cross-section. In  FIG. 6 , a portion of a conforming carrier  102  is shown in cross section in phantom lines. The slot alignment protrusions  123  each engage a corresponding slot  108  in the carrier  102 . Because the slot alignment protrusions  123  are squarely aligned or properly registered with their corresponding slots  108 , the foot  109  can seat flushly against the seating pad  119 . A portion of a nonconforming carrier is shown in cross section in phantom lines in  FIG. 7 . In the case of this nonconforming carrier  102 , the slot alignment protrusions  123  are not squarely or fully aligned or properly registered with their respective slots  108 . The slot alignment protrusions  123  thus interfere with the carrier  102  and prevent the carrier  102  from seating flush within the pocket  106 .  
         [0029]     It should be appreciated that the embodiment described thus far could be modified in order to accommodate carriers  102  of various designs. For instance the pockets  105  and  106  can be formed in virtually any shape and size by varying the characteristics of the rails used to form the pockets  105  and  106 . The number and placement of the alignment protrusions  121 , alignment passages  122 , and slot alignment protrusions  123  within pockets  105  and  106  can be modified to be reciprocal with the desired specifications of the carrier  102 , for example cooperatively mate with corresponding features of the carrier. It should be appreciated that rather than using a single top rail  115  and a single bottom rail  116  that span both pockets  105  and  106 , separate rails could be used for each pocket. Furthermore, it is not necessary to include all of the alignment aids, that is pockets, alignment protrusions, alignment passages and slot alignment protrusions, in order to successfully utilize the checker  101 . Various combinations of the alignment aids may be sufficient to create a viable checker  101  according to the present invention.  
         [0030]     In operation and use, the carrier checker  101  acts as a tool to assess a disk carrier  102 , or at least a portion of the disk carrier  102 , for compliance with a specified size and shape. Disk carriers  102  that conform to the desired shape and size can be identified as “good” or “conforming” disk carriers  102 . Disk carriers  102  that do not conform to the desired shape and size can be identified as “bad” or “nonconforming” disk carriers  102 .  
         [0031]     In order to assess whether a particular disk carrier  102  is a good or bad carrier, a user attempts to seat the feet  104  and  109  of the carrier  102  into their corresponding pockets  105  and  106 . If the feet  104  and  109  easily seat fully within the pockets  105  and  106 , then the carrier  102  is properly dimensioned and can be identified as a good carrier. If, on the other hand, the carrier  102  do not fully seat within the pockets  105  and  106 , then the carrier  102  is not properly dimensioned and can be identified as a bad carrier  102 .  
         [0032]      FIG. 8  illustrates one manner of attempting to seat the carrier feet  104  and  109  within the pockets  105  and  106 . The carrier  102  is tilted so that the first foot  104  is elevated relative to the second foot  109 . The second foot  109  is inserted into the second pocket  106 . The carrier  102  is then released so that the first foot  104  is allowed to fall into the first pocket  105  to the position shown in  FIG. 9 . If both feet  104  and  109  seat fully within their respective pockets  105  and  106  under the force of gravity without the need to force them into place, then the carrier  102  is a good carrier. If on the other hand, either, or both, of the feet  104  and  109  do not seat fully within their respective pockets  105  and  106 , then the carrier  102  is identified as a bad carrier.  
         [0033]      FIG. 10  shows a detailed view of the appearance of a corner of a good carrier  102  that is fully seated within the second pocket  106 . The foot  109  sits flat against the seating pad  120 . While not visible in  FIG. 10 , it should be appreciated that when the good carrier  102  of  FIG. 10  is fully seated in the second pocket  106 , the alignment pin  110  is received within the alignment passage  122  in the seating pad  120 , and the alignment protrusion  121  on the first seating pad  119  is received within the alignment aperture  111  on the first foot  104  (see  FIG. 4 ). The slot alignment protrusions  123  are in engagement with their respective slots  108  (see  FIG. 6 ), when the good carrier  102  is fully seated.  
         [0034]      FIG. 11  shows a detailed view of a portion of a bad carrier  102  that does not seat fully within the second pocket  106  in that at least one of the alignment elements, that is rails, alignment protrusion, alignment passage, or slot alignment protrusion, interferes with its corresponding feature on the carrier  102 . As a result, the carrier  102  is prevented from fully seating in the pocket  106 .  
         [0035]     The above described embodiments of the invention thus provide a tool and method for quickly and easily assessing whether a disk carrier  102  conforms to a desired size and shape.  
         [0036]     Although the present invention has been described with a certain degree of particularity, it is understood that the disclosure has been made by way of example, and changes in detail or structure may be made without departing from the spirit of the invention as defined in the appended claims. For example, the location and number of alignment protrusions  121  and alignment passages  122  can be varied in other embodiments to match the characteristics of a different disk carrier  102 .