Abstract:
An apparatus and method for positioning packaged semiconductor devices having different rectangular shapes and sizes. A positioning apparatus includes an adjustable alignment guide releasably coupled to a base. The adjustable alignment guide may be positioned along a first axis to partially define a recess into which the packaged semiconductor devices are placed during positioning. The positioning apparatus may also include additional adjustable alignment guides that may be positioned along the first or a second axis to further define the recess into which the packaged semiconductor device is to placed during positioning. The adjustable alignment guides may have alignment surfaces against which the integrated circuit rests when placed into the recess that is partially defined by the alignment surfaces. The adjustable alignment guides may be slidably attached to a base, and moved by sliding the guides to an appropriate position according to the shape and size of the packaged semiconductor device to be positioned.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional of pending U.S. patent application Ser. No. 09/321,266, filed May 27, 1999. 
    
    
     TECHNICAL FIELD 
     The present invention relates generally to the field of semiconductor device manufacturing, and more particularly, to an apparatus and method of coarsely aligning a packaged semiconductor device. 
     BACKGROUND OF THE INVENTION 
     Semiconductor devices are typically fabricated on thin wafers of silicon. Several die are produced on each wafer, with each die representing a single semiconductor device. Each die on a wafer is tested for gross functionality, and sorted according to whether the die passes or fails the gross functionality test. After being sorted according to gross functionality, the wafers are cut using a wafer saw and the individual die are separated. The die determined to be non-functional are scrapped. The functional die are packaged and further tested to ensure that each packaged device satisfies a minimum level of performance. The reliability of the packaged devices are tested by further subjecting them to a “burn-in” period where the devices are tested at an elevated voltage and elevated temperature for a period of time. 
     Functional devices may be permanently packaged by encapsulating the die in a plastic package, or temporarily packaged by mounting the die in a ceramic package. Packaging the functional devices facilitates handling of the device and also protects the die from damage during performance and reliability testing. The packaged devices are typically stored in carrying trays having recesses into which the device is placed. The packaged devices are transported from one test station to another in the carrying trays. 
     Automated device handlers are used during the testing and burn-in phase to facilitate handling of the packaged devices. The handlers automatically unload the packaged devices from the carrying trays, and transport and position the devices for testing by a test unit. The handler then reloads the packaged devices into a carrying tray when testing is complete. 
     When unloading a packaged device from a carrying tray, the handler may need to align the packaged device prior to placing it into a handler boat. Although the carrying tray provides some alignment, it may not be within the precision required for placement into the handler boat without damaging the packaged device. A mechanical structure known as a precisor is used to coarsely align the packaged device. The packaged device is placed into a recess in the precisor for alignment. The packaged device is then removed from the precisor and placed into the handler boat to be transported within the automated device handler to a handler chuck. 
     The handler chuck receives the packaged device from the handler boat and positions it to come in contact with a contactor. The contactor has a series of conductors that electrically contact the leads of the packaged device. A tester unit connected to the contactor applies a series of signals to the packaged device through the series of conductors in order to test the functionality of the device. Before the handler chuck puts the packaged device into contact with the contactor, the packaged device must be correctly oriented. Although the contactor is designed to receive a packaged device that is not precisely oriented to the contactor, the packaged device must still be coarsely aligned within a certain measure. An incorrectly oriented packaged device may be damaged when forced into contact with the contactor, or incorrectly tested when the leads of the packaged device contact the incorrect conductors because the device is misaligned with respect to the contactor. 
     After testing is complete, the packaged device is pulled away from the contactor by the handler chuck and returned to the handler boat. The packaged device is transported by the handler boat to be reloaded into a carrying tray. 
     Shown in FIG. 1 is an example of a conventional fixed alignment tooling  2  used for coarsely aligning a packaged device  3 . The fixed alignment tooling  2  may be used in the singulated device handling applications described previously, that is, for a precisor, or handler boat or chuck. The fixed tooling  2  includes a base  4  having a recess  6  defined by chamfered surfaces  8   a-d . The packaged device  3  is coarsely aligned by the chamfered surfaces when placed into the recess  6  and rests on either on the package balls or on the package substrate if relief for the ball pattern is provided. The chamfered surfaces  8   a-d  also guide the packaged device  3  into the recess  6  when slightly skewed and facilitate positioning of the packaged device  3  within the recess  6 . The coarsely aligned packaged device  3  can then be transported or transferred within the automatic handler positioned with the proper alignment. 
     It can be seen that the fixed tooling  2  works only for a packaged device having a particular shape and size. The fixed alignment tooling  2  requires replacement when the shape or size of the packaged device changes. The costs involved with changing the fixed tooling  2  is considerable when refitting an entire test area. For example, the fixed tooling of the precisor, handler boats and chucks would need to be retrofitted to accommodate a packaged device having a new shape or size. Fortunately, the need to change the fixed tooling  2  arises infrequently because the shape and size of current device package types, for example, SOJ, ZIP, or TSOP packages, are not affected when the size of the die encapsulated within the package is decreased. 
     The die size of a semiconductor device is typically shrunk in an effort to increase the number of die fabricated on each wafer, and consequently, increase the number of die potentially yielded by each wafer. Die shrinks occur throughout the lifetime of a semiconductor device. The shape and size of the package is generally unaffected by a die shrink because each succeeding generation of smaller die are simply encapsulated in the same sized package as their larger progenitor. Thus, the infrequency of changing the fixed tooling  2  allows for the associated costs to be amortized over a relatively long period of time. However, as the shape or size of device packages change more frequently during the lifetime of a device, the relative costs will increase. Therefore, it can be appreciated that there is a need for an apparatus that can coarsely align packaged semiconductor devices and minimize the costs associated with changing the fixed toolings whenever the size of the device package changes. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an apparatus and method for positioning packaged semiconductor devices having different rectangular shapes and sizes. A positioning apparatus includes an adjustable alignment guide that may be positioned along a first axis to partially define a recess into which the packaged semiconductor devices are placed during positioning. The adjustable alignment guide may be an alignment surface against which the integrated circuit rests when placed into the recess partially defined by the alignment surface. The adjustable alignment guide may be slidably attached to a base, and moved by sliding the guide to the appropriate position according to the shape and size of the packaged semiconductor device to be positioned. The positioning apparatus may also include additional adjustable alignment guides that may be positioned along the first or a second axis to further define the recess into which the packaged semiconductor device is to placed during positioning. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an isometric view of a conventional coarse alignment tooling. 
     FIG. 2 is an isometric view of a coarse alignment tooling according to an embodiment of the present invention. 
     FIG. 3 is an isometric view of the coarse alignment tooling of FIG.  2 . 
     FIGS. 4A-D are partial isometric views of the coarse alignment tooling according to several embodiments of the present invention. 
     FIG. 5 is an block isometric view of an automated coarse alignment tooling according to another embodiment of the present invention. 
     FIG. 6 is a block diagram of a test system including an automated handler having the coarse alignment tooling of FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As discussed previously, the fixed alignment tooling must be changed whenever the shape or size of the package device changes. As the frequency with which the package shape or size changes increases, the relative costs associated with re-fitting singulated device handling equipment with new fixed alignment toolings will also increase. Exacerbating this problem is the fact that the frequency with which die shrinks occur has accelerated as a result of a greater demand for smaller and faster semiconductor devices. 
     Additionally, new package types are currently being developed that have shapes and sizes that are affected by the size of the encapsulated die. For example, fine pitch ball grid array (FBGA) packages, and other chip scale packages (CSPs) have package dimensions that are slightly larger than the dimension of the encapsulated die. Therefore, each time a die shrink occurs, the size of the resulting packaged device also decreases. Consequently, the fixed alignment tooling must be changed to accommodate the smaller sized package each time a die shrink occurs. As mentioned previously, die shrinks are occurring more frequently during the lifetime of a semiconductor device. 
     The present invention is embodied in an adjustable alignment tooling  12  shown in FIG.  2 . The adjustable alignment tooling  12  may be used in precising systems utilized in singulated device handling equipment, such as those discussed above. The adjustable alignment tooling  12  may be adjusted to accommodate various package shapes, thus reducing the need to replace the fixed alignment tooling whenever the shape or size of the device package changes. The adjustable alignment tooling  12  is especially useful in light of the recent development in CSPs. 
     The adjustable alignment tooling  12  includes a base  14  and adjustable alignment fixtures  18   a-d  attached to the base  14 . Each of the adjustable alignment fixtures  18   a-d  has a respective alignment surface  20   a-d.  The adjustable alignment fixtures  18   a-d  are adjusted so that the respective alignment surfaces  20   a-d  define a recess  22  into which the packaged semiconductor device is placed for coarse alignment. The alignment surfaces  20   a-d  are chamfered to facilitate placement of the packaged semiconductor into the recess  22  during alignment. Once the packaged semiconductor has been placed into the recess  22 , the packaged semiconductor device is coarsely aligned to the correct orientation. In the case where the packaged semiconductor device is in the form of a ball grid array (“BGA”), the device will rest on either the solder balls, or on the package substrate if relief for the solder ball pattern (not shown) is provided. 
     The adjustable alignment fixtures  18   a,    18   c  and  18   b,    18   d  may be adjusted along two perpendicular axes  26  and  28 , respectively, to accommodate coarse alignment of packaged semiconductor devices having different rectangular shapes and sizes. The adjustable alignment tooling  12  is adjusted by moving the adjustable alignment fixtures  18   a-d  toward or away from the oppositely positioned adjustable alignment fixture, thereby decreasing or increasing the area of the recess  22 . That is, adjustable alignment fixtures  18   a  and  18   c  may be moved along the axis  26 , and adjustable alignment fixtures  18   b  and  18   d  may be moved along the axis  28 , to position the respective alignment surfaces  20   a-d  and define a recess  22  having an appropriate shape and size with respect to a packaged semiconductor device. 
     For example, a packaged device  70  has a shape and size defined by a length  72 , a width  74 , and a height  76 . The adjustable alignment fixtures  18   a-d  are shown in FIG. 2 as being positioned to define a recess  22  and a surface  24  having nearly the same dimensions as the length  72  and the width  74 . Thus, when the packaged device  70  is placed into the recess  22  it will be coarsely aligned. Although the alignment surfaces  20   a-d  do not fully enclose the recess  22 , the flat surfaces of the alignment surfaces have a length sufficient to properly orient the packaged device  70  when placed into the recess  22 . 
     Now consider a packaged device  80 , as shown in FIG. 3, having a length  82 , a width  84 , and a height  86 , where the length  82  and the width  84  is less than the length  72  and width  74 , respectively. The packaged device  80  will not be coarsely aligned if placed into the recess  22  because the dimensions of the recess  22  are too great to properly orient the packaged device  80 . 
     In order for the adjustable alignment tooling  12  to correctly align the packaged device  80 , the adjustable alignment fixtures  18   a-d  should be positioned so that the respective alignment surfaces  20   a-d  define a recess  22  and a surface  24  having nearly the same dimensions as the length  82  and the width  84 . This can be accomplished by moving the alignment fixtures  18   a  and  18   c  toward one another along the axis  26  until the distance separating the alignment surfaces  20   a  and  20   c  along the surface  24  is slightly less than the width  84 . Similarly, the alignment fixtures  18   b  and  18   d  should be moved toward one another along the axis  28  until the distance separating the alignment surfaces  20   b  and  20   d  along the surface  24  is slightly less than the length  82 . When the adjustable alignment fixtures  18   a-d  are positioned in such a manner, the packaged device  80  will be coarsely aligned to the proper orientation when placed into the recess  22  and rests on the alignment surfaces  20   a-d.    
     As will be appreciated by a person of ordinary skill in the art, the adjustable alignment tooling  12  may be adjusted to correctly align packaged devices having different rectangular shapes, as well as packaged devices having different sizes. For example, if only the width  74  were to decrease while the length  72  were to remain constant (FIG.  2 ), the adjustable alignment fixtures  18   a  and  18   c  could be moved toward one another along the axis  26  so that the packaged device  70  could still be correctly aligned by the adjustable alignment tooling  12  when positioned in the recess  22 . Similarly, the adjustable alignment tooling  12  could have only two adjacent adjustable alignment fixtures and still accommodate packaged devices of various rectangular shapes and sizes. For example, with reference to FIG. 2 the alignment fixtures  18   a  and  18   d  would have fixed positions while alignment fixtures  18   b  and  18   c  would remain adjustable along the axes  28  and  26 , respectively. When correctly aligning a different shaped or sized packaged device, only adjustable alignment fixtures  18   b  and  18   c  would be adjusted to accommodate the new packaged device. One corner of the recess  22  is defined by the fixed alignment fixtures  18   a  and  18   d , while the diagonal corner of the recess  22  is defined by the adjustable alignment fixtures  18   b  and  18   c.  By defining two corners of the recess  22 , the new packaged device can be correctly aligned when placed into the resulting recess  22 . 
     As illustrated above, the number of adjustable alignment fixtures may range from one to four, depending on the flexibility desired and the specific application. In the case where the adjustable alignment tooling  12  has only one adjustable alignment fixture, it can accommodate packaged devices having different dimensions only along one axis, that is, either a different length or width. 
     The adjustable alignment fixtures  18   a-d  may be positioned on and attached to the base  14  in a variety of manners. One example is shown in FIG. 4A with respect to the adjustable alignment fixture  18   c.  A slot  30  is formed through the alignment fixture  18   c.  A pin  34  is fixed to the base  14  and protrudes perpendicular to the surface of the base to fit into the slot  30 . A screw  32  also fits through the slot  30  and threads into a threaded hole formed in the surface of the base  14 . The pin  34  and the screw  32  are aligned along the axis  26 . In this arrangement, movement of the adjustable alignment fixture  18   c  will be along the axis  26  when the screw  32  is loosened. After the adjustable alignment fixture  18   c  is properly positioned, the screw  32  is tightened snug so that the overlapping portion of the screw head contacting the upper surface of the adjustable alignment fixture  18   c  will hold it in place. If so desired, the pin  34  may be replaced by a second screw if a second threaded hole is formed into the base  14 . 
     Another arrangement for attaching the adjustable alignment fixtures  18   a-d  to the base  14  is shown in FIG. 4B with respect to the adjustable alignment fixture  18   c.  Two slots  36   a  and  36   b  are formed through the alignment fixture  18   c.  The two slots  36   a  and  36   b  are formed laterally from each other and parallel to the axis  26 . Two screws  38   a  and  38   b  fit through slots  36   a  and  36   b,  respectively, and thread into threaded holes formed in the base  14 . The alignment fixture  18   a  may be moved in a direction along the axis  26  when the screws  36   a  and  36   b  are loosened. Once correctly positioned, the alignment fixture  18   a  may be held in place by tightening the screws  36   a  and  36   b  snug against the upper surface of the alignment fixture  18   a.    
     The adjustable alignment fixtures  18   a-d  may also be attached to the base  14  through the arrangement shown in FIG. 4C with respect to alignment fixture  18   c.  A slot  40  is formed through the base  14 . A screw  42  is fit through the slot  40  and threads into a threaded hole formed into the lower surface of the alignment fixture  18   c.  A recessed region is also formed in the base  14  along the slot  40  to accommodate the head of the screw  42 . A pin  44  protrudes perpendicularly from the lower surface of the alignment fixture  18   c  and fits into the slot  40 . The pin  44  and the screw  42  are both aligned along the axis  26  to ensure that movement of the alignment fixture  18   c  is along the axis  26 . The alignment fixture  18   c  may be adjusted to the correct position and held in place by tightening the screw  42  snug. 
     The adjustable alignment fixtures  18   a-d  may also be attached to the base  14  through the arrangement illustrated in FIG. 4D with respect to alignment fixture  18   c.  Two pins  52 ,  54  protruding from the bottom surface of the adjustable alignment fixture  18   c  fit into a series of evenly spaced holes  56  formed in the surface of the base  14 . The alignment fixture  18   c  can be moved by lifting it away from the surface of the base  14  until the two pins  52 ,  54  are removed from the holes  56 . The alignment fixture  18   c  is then repositioned by reinserting the pins  52 ,  54  into another set of the holes  56 . The frictional fit between the pins  52 ,  54  and the holes  56  will prevent the alignment fixture from being inadvertently removed. 
     The movement of the adjustable alignment fixtures  18   a-d  may also be performed through automated means, as shown in FIG. 5, if the alignment fixtures  18   a-d  are coupled to a computer driven actuating system  60 . Such an arrangement allows the adjustable alignment tooling  12  to be quickly adjusted to accommodate a variety of rectangular shaped device packages. A computer driven actuation system having a computer  62  and an actuator  64  may be incorporated into a handler so that the computer  62  may be programmed to move the adjustable alignment fixtures  18   a-d  via connecting arm  66  to predetermined positions whenever a different shaped packaged device is tested. An automated actuation system as described is well known in the art, and may be employed in the precising systems utilized in singulated handling equipment described previously. 
     Although specific arrangements of attaching the adjustable alignment fixtures  18   a-d  to the base  14  have been provided above, the principles of the present invention are applicable regardless of the specific form of attachment. Accordingly, the present invention is not limited by the specific method of attaching the adjustable alignment fixtures  18   a-d  to the base  14 . 
     A person of ordinary skill in the art will appreciate that the minimum size of the recess  22  defined by the adjustable alignment fixtures  18   a-d  is limited by the length of the respective alignment surfaces  20   a-d.  The minimum size of the recess  22  will result when the adjustable alignment fixtures  18   a-d  are moved toward one another until the adjacent alignment fixtures butt against the alignment fixture being moved. This situation is illustrated in FIG.  3 . However, the adjustable alignment fixtures  18   a-d  may be replaced with adjustable alignment fixtures having alignment surfaces  20   a-d  with decreased widths. Consequently, the respective adjustable alignment fixtures  18   a-d  may be moved closer together to accommodate smaller packaged devices. 
     Shown in FIG. 6 is a block diagram of a test system  70  for packaged semiconductor devices. An automated handler  72  is includes a loading mechanism  74  that loads packaged semiconductor devices into the automated handler  72 . The devices are placed into a precisor  75  to be coarsely aligned. The precisor includes an embodiment of an adjustable alignment tooling  12  according to the principles of the present invention. A handler boat  76  receives the packaged devices from the precisor  75  and provides the device to a handler chuck  78 . The handler boat  76  also includes an embodiment of the adjustable alignment tooling  12  so that the device is coarsely aligned when transferred to the handler chuck  78 . The handler chuck  78  receives the device from the handler boat  76  and positions the device in physical proximity to a test head  84  having a contactor  82 . As mentioned previously, when the device comes into contact with the contactor  82 , electrical signals generated by a test unit  86  may be applied to the device. In order to correctly position the device within the contactor  82 , the handler chuck also includes an embodiment of the adjustable alignment tooling  12  that aligns the device with respect to the contactor  82 . After testing of the device is complete, the handler chuck  78  withdraws the device from the contactor  82 , and returns the device to the handler boat  76 . The handler boat  76  receives the device and provides the device to an unloading mechanism  80 , which unloads the device from the automated handler  72  and returns the device to a carrying tray. 
     From the foregoing it will be appreciated that although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention. For example, the adjustable alignment fixtures  18   a-d  have been shown as being positioned to align a packaged device having a square shape. However, the adjustable alignment fixtures  18   a-d  may be adjusted for a packaged device having a rectangular shape as well. Furthermore, the present invention has been described with respect to handling a packaged device during testing. However, some or all of the principles of the present invention are applicable to other operations where singulated packaged device handling equipment is used. For example, tape and reel, device inspection, and packing operations. Furthermore, as will be appreciated by one skilled in the art, a plurality of adjustable alignment toolings according to the embodiments described previously may be used together to facilitate the mass production of semiconductor devices. For example, with reference to FIG. 6, the precisor  75 , handler boat  76 , and the handler chuck  78 , may each include more than one adjustable alignment tooling  12  so that several semiconductor devices may be tested simultaneously. Accordingly, the invention is not limited except as by the appended claims.