Abstract:
A tool and method is described to decide partial wafer sizes to process multiple random sizes of wafers in pick and place equipment for wafermap operation. The tool identifies the wafer and gets wafermap data. The position of one or more cutters is displayed. The position of the cutters relative to the wafer is displayed. The tool generates and displaying the results of the type of dies in each partial that would result from a cut according to said displayed position of the cutters.

Description:
FIELD OF INVENTION  
         [0001]    This invention relates to pick and place equipment in semiconductor manufacturing and more particularly to a tool and method to decide partial wafer sizes to process multiple random size wafers.  
         BACKGROUND OF INVENTION  
         [0002]    The wafermap process eliminates the inking of reject die at the wafer fab by using the map data available from the probe test to position the wafer to exact location of all the good die on the Die Bonder or Tape &amp; Reel. Hence, direct jumps to good die are possible without scanning the whole wafer. See FIG. 1 for a typical wafer.  
           [0003]    In wafermapping environment, the wafermap data contains good, bad, plug and edge dies coordinates with reference to a Reference die of a wafer. A Bin in wafermap data is a category of dies. For example, Bin  1  is all good first grade dies, Bin  2  is all good second grade dies, Bin  3  is all Plug dies, Bin  4  is all bad edge dies and Bin  5  is remaining bad dies.  
           [0004]    With small die wafers having high chips per wafer count, the wafers are also processed in halves, quarters and other sizes to match the production lot size at the Assembly And Test site. Thus, partial wafer processing is very much an operational requirement for small die wafers unlike large die wafers.  
           [0005]    Since each good die is valuable a partial wafer is even more valuable. Partial wafers are formed by cutting a wafer into half (two pieces) or quarter (four pieces) or other different size pieces (multiple pieces). See FIG. 2 for a half pieces, FIG. 3 for quarter pieces and FIG. 4 for other multiple pieces. A fabricator may know how many good dies are needed but with or without wafermap operation, it is difficult to decide for a production demand where to cut a wafer and how many pieces are required. Currently, no known tool exists to perform this type of operation.  
         SUMMARY OF INVENTION  
         [0006]    In accordance with one embodiment of the present invention a method and tool for deciding and providing a partial wafer size for production demands includes the steps of getting wafermap data, providing the coordinates of the one or more cutters relative to the wafer and moving the one or more cutters relative to the wafer to determine the cut of the wafer to form the desired partial wafer.  
           [0007]    In accordance with another embodiment of the present invention the method steps include providing the coordinates of a pair of orthogonal oriented wafer cutters, getting wafermap data of good dies and moving the coordinate positions of the cutters relative to the wafer and displaying the results of the type of dies in each partial that would result from the cut according to said wafermap data.  
           [0008]    In accordance with another embodiment of the present invention the tool automatically queries the number of good dies wanted and the type of partial wafer selected and the system automatically decides the cut position or one or more cutters.  
       
    
    
     DESCRIPTION OF DRAWING  
       [0009]    [0009]FIG. 1 illustrates a typical wafer.  
         [0010]    [0010]FIG. 2 illustrates half wafers.  
         [0011]    [0011]FIG. 3 illustrates quarter wafers.  
         [0012]    [0012]FIG. 4 illustrates multiple partial wafers cut perpendicular to the flat.  
         [0013]    [0013]FIG. 5 illustrates a tool according to one embodiment of the present invention.  
         [0014]    [0014]FIG. 6 is a flow diagram according to one embodiment of the present invention.  
         [0015]    [0015]FIG. 7 illustrates two orthogonal cutters for cutting the wafer.  
         [0016]    [0016]FIG. 8 illustrates two cutters with bin details according to one embodiment of the present invention.  
         [0017]    [0017]FIG. 9 is a flow diagram according to another embodiment of the present invention.  
         [0018]    [0018]FIG. 10 illustrates two cutters and queries to select the position of the two cutters.  
         [0019]    [0019]FIG. 11 illustrates two cutters with the bin details of quarter wafer type.  
         [0020]    [0020]FIG. 12 illustrates two cutters with bin details of half wafer type.  
         [0021]    [0021]FIG. 13 illustrates two cutters with bin details of a partial wafer. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0022]    Referring to FIG. 5 there is illustrated a tool  10  according to one embodiment of the present invention. The tool  10  is connected to a cutting system  11  including a wafer table and a pair of movable cutters. The tool  10  further includes a processor  17 , a keyboard  19  and a display  21 . The tool  10  at display  21  displays the wafer on the wafer table and illustrates by lines  13  and  15  on the display the coordinate positions of orthogonal cutters in the cutter system  11 . The cutters extend in the X and Y directions and are orthogonal to each other. One of the cutters  13  as illustrated by the display is movable in the Y direction and the other orthogonal cutter  15  illustrated by the display is movable in the X direction. The cutting system  11  includes a sensor  14  for sensing the position of the cutters relative to the wafer on the wafer table. The processor  17  receives input signals from the sensor  14  indicating the position of the orthogonal cutters and this is displayed on the display screen  21 . The processor  17  also receives wafermap data from an external server or from its hard disk memory or floppy disk memory. The keyboard  19  also provides inputs to processor  17 . The processor  17  processes the inputs and displays a wafermap and data at display  21 .  
         [0023]    The processor  17  includes a program that follows the steps illustrated by one embodiment in FIG. 6. As illustrated by Step  101 , the tool  10  gets the wafer identification by the user entering the identification number or characters into the processor by the keyboard  19 . The processor  17  gets the wafermap data file that includes the good and bad die locations and bin numbers from a wafermap data server or local disk file or floppy disk file (Step  102 ).  
         [0024]    Referring to FIG. 5 the position of the pair of orthogonal pair of cutters (illustrated by cutters  13  and  15  in the display) is sensed at sensor  14  and provided to the processor  17  and on the display  21 . The processor  17  processes the wafermap data and the sensed coordinates of the orthogonal cutters of the cutter system  11  to display the coordinate position of the orthogonal cutters  13  and  15  and displays the wafermap on the display  21  (Step  103 ). FIG. 7 illustrates the tool  10  display  21  of the position of the two cutters  13  and  15  and the wafer before any selection of coordinates on the wafer.  
         [0025]    When the user places the illustrated cutters  13  and  15  on the wafer illustrated in the display by the tool  10  the bin details for each quadrant (Step  104 ) or each partial wafer resulting from a cut at the indicated positions of the orthogonal cutters is generated and displayed.  
         [0026]    [0026]FIG. 8 illustrates the bin details for each quadrant for the displayed position of the two cutters  13  and  15 . For quadrant Q 1 , the bin details are: Bin  1 =20, Bin  9 =7 and Bin  10 =8. For quadrant Q 2 , the bin details are: Bin  1 =32, Bin  9 =13 and Bin  10 =9. For quadrant Q 3 , the bin details are: Bin  1 =60, Bin  9 =26 and Bin  10 =21. For quadrant Q 4 , the bin details are: Bin  1 =25, Bin  9 =10, and Bin  10 =18. Bin  1  usually relates to the best dies.  
         [0027]    The user of the tool  10  moves the illustrated position of the cutters so that the partial wafer cuts a partial wafer that fits the demand. For example, if 25 good dies are requested, the partial wafer could be quadrant Q 4  in the above illustration. The position of the illustrated cutters on the display is moved to the position where the partial wafer section is the one that provides the desired number of good dies. Similarly, the cut position may be based on the secondary bin dies or first and secondary dies. This coordinate information may then be sent to the cutting system  11  to cut the partial wafer.  
         [0028]    [0028]FIG. 9 illustrates the step of a program in the processor  17  in accordance with another embodiment of the present invention. The user enters the identification number of the wafer in the keyboard (Step  201 ) as done previously. The processor  17  gets the wafermap data (Step  202 ) from the wafermap server or local disk or floppy disk. The wafermap is displayed (Step  203 ). The system also displays the two cutter coordinate positions.  
         [0029]    In Step  204  the tool  10  requests entry by the user of the number of dies in a particular Bin number such as good or best dies in Bin  1 . In FIG. 10 this is represented by the query Bin  1 =? Other Bin numbers may be selected.  
         [0030]    In Step  205  the tool requests the user to input the partial wafer type such as half or quarter? The partial wafer type in FIG. 10 illustrates this.  
         [0031]    The number of dies with the Bin such as Bin  1  and the type of partial wafer type is then inputted by the user (Step  206 ).  
         [0032]    The processor  17  automatically searches out the wafermap data for a match of user inputted partial wafer type and user inputted number dies of a Bin type, such as good dies in Bin  1  for example, and determines and generates at display  21  the coordinate position of the cutters and the partial wafer (Step  207 ). See FIG. 11. The display for half wafer types is illustrated with Bin the numbers is illustrated in FIG. 12. The display for partial wafer is illustrated with Bin numbers in FIG. 13.  
         [0033]    The user may then send the determined position of the cutters from the tool  10  in FIG. 5 to the cutting system  11  and the selected partial wafer is cut.  
         [0034]    While the invention has been described with reference to two embodiments, it will be apparent by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.