Abstract:
An apparatus and method is provided for recognizing a working position of a device transfer system in a semiconductor device test handler. The working position of a transfer unit of the handler is adjusted based on tray and change kit positions to allow components to be quickly and precisely loaded and transferred when various kinds of semiconductor devices are tested in the handler. A laser sensor which detects a color change of an object is provided with the transfer unit, and scans corners of the tray and change kits to acquire position information related to the tray and change kits. The working position of the transfer unit is calculated using basic handler information contained in the control unit of the handler and the acquired information.

Description:
This application claims the benefit of the Korean Application No. P2001-80155 filed on Dec. 17, 2001, which is hereby incorporated by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an apparatus and method for recognizing a working position of a device transfer system in a semiconductor device test handler enabling to recognize to reset the working positions of the device transfer system for trays and change kits as replacing components fast and precisely when various kinds of semiconductor devices are tested in the handler. 
   2. Discussion of the Related Art 
   Generally, semiconductor devices produced in a production line undergo tests for checking whether to be good or fail before shipment. 
   A handler is a device for testing such semiconductor devices. The handler uses a semiconductor device transfer system to transfer semiconductor devices received on a tray to another process line automatically, loads the semiconductor devices on a test socket of a test site to carry out a demanded test thereon, and classifies the tested semiconductor devices into various levels to unload them on the tray. The handler carries out such steps repeatedly to perform the tests. 
     FIG. 1  illustrates a layout of a general handler for semiconductor device test. 
   Referring to  FIG. 1 , in a front part of a handler body  1 , formed are a loading unit  2  on which trays receiving test-expecting semiconductor devices thereon are stacked and an unloading unit  3  having a plurality of trays receiving test-completed semiconductor devices classified into good products and fail products in accordance with test results. And, a soaking plate  7  is installed in rear of the loading unit  2 . The soaking plate  7  includes a heating means (not shown in the drawing) and a cooling means (not shown in the drawing) inside to heat or cool the test-expecting semiconductor devices to a predetermined temperature for temperature test. 
   And, a reject multi-stacker  5 , on which a plurality of trays are loaded to receive the semiconductor devices classified by grade into the fail products according to the test results, is installed in rear of the unloading unit  3 . 
   In a test site  10  located at the foremost rear part of the handler body  1 , a test socket  11  connected electrically to an external testing device is installed to test a performance of each of the semiconductor devices. Over the test sockets  11 , formed are first and second index heads  12   a  and  12   b  installed to move horizontally to pick up to load the semiconductor devices, which are transferred to standby positions at both sides of the test sockets  11 , on the test sockets  11  as well as to pick up to retransfer the tested semiconductor devices on the test sockets  11  to the standby positions at both sides. 
   In the very front of the test site  10 , first and second shuttles  8   a  and  8   b  are installed to move back and forth. The first and second shuttles  8   a  and  8   b  receive to transfer the semiconductor devices from the loading unit  2  or the soaking plate  7  to the standby positions at both sides of the test sockets  11  of the test site  10 . At one sides of the first and second shuttles  8   a  and  8   b , third and fourth shuttles  9   a  and  9   b  are installed to move back and forth, respectively. The third and fourth shuttles  9   a  and  9   b  receive to transfer the test-completed semiconductor devices from the test site  10  to an outside of the test site  10 . 
   Fixing frames  13  are installed at the front end of the handler body  1  and over the very front side of the test site  10  across the handler body  1 , respectively. A pair of movable frames  14   a  and  14   b  are installed at the fixing frames  13  to move right and left along the fixing frames  13 . And, two device transfer units  15  are installed at the movable frames  14   a  and  14   b  to move along the movable frames  14   a  and  14   b  to pick up semiconductor devices, respectively. Each of the device transfer units  15  includes a plurality of pickers (not shown in the drawing) to transport a plurality of the semiconductor devices simultaneously. 
   Meanwhile, a handler is constituted to carry out a test on such semiconductor devices as QFP, BGA, SOP, and the like. After one species of the semiconductor devices have been tested, another species of the semiconductor devices are tested. In such a case, a change kit including the tray, soaking plate  7 , shuttles  8   a ,  8   b ,  9   a , and  9   c , test sockets  11 , and the like is replaced by another change kit fitting to the semiconductor device species to carry out the test. 
   In this case, the change kits replaced according to the species of the test-expecting semiconductor devices differ from each other in pitches and sizes of landing units where the semiconductor devices land. Hence, working sections of the device transfer unit  15  should be reset. Namely, as options of the change kits are changed, positions, at which the device transfer unit  15  picks up the semiconductor devices, are varied. Hence, displacements of the device transfer unit  15  and pitches between the pickers (not shown in  FIG. 1 ) of the device transfer unit  15 , elevating heights of the pickers, and the like should be reset. 
   However, a worker checks the options of the change kits replaced by the above-explained manner one by one using a measurement jig and inputs the measurements to a control unit (not shown in the drawing) of the handler for programming, thereby setting a working position. In this case, a probability of error occurrence during input is high and a working position setup takes too much time. Hence, daily productivity is reduced and overall efficiency of the test work is decreased. Such problems become more serious when the number and species of the change kit for replacement increase. 
   SUMMARY OF THE INVENTION 
   Accordingly, the present invention is directed to an apparatus and method for recognizing a working position of a device transfer system in a semiconductor device test handler that substantially obviate one or more problems due to limitations and disadvantages of the related art. 
   An object of the present invention is to provide an apparatus and method for recognizing a working position of a device transfer system in a semiconductor device test handler enabling to recognize to reset the working position of the device transfer system for change kits including trays to be replaced as a species of test-expecting semiconductor devices is varied. 
   Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
   To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, in an apparatus of recognizing the working position of a device transfer system for transferring semiconductor devices in handler, the apparatus comprising a laser sensor being horizontally movable and discharging a laser beam downward to a base plate on which one or more trays and change kits are provided and generating a corresponding output signals; a control unit determining locations of the trays and change kits with respect to the base plate upon receiving the output signal from the laser sensor; and a transfer unit moving toward the determined location for transferring semiconductors into or from the trays and change kits, wherein the laser sensor being rigidly fixed to one side of the transfer unit. 
   In another aspect of the present invention, in a method of recognizing a working position of a transfer unit using the above-described apparatus, the method comprises a first step of inputting a species of a test-expecting semiconductor device and a basic information of options of trays and change kits to the control unit; a second step of moving the transfer unit and the laser sensor to a position adjacent to one vertex of the tray and carrying out a scan of a laser sensor by moving the transfer unit in horizontal and vertical directions X and Y; a third step of getting a first position value P 1 y of a point meeting a corner of the tray while the laser sensor scans in the vertical direction Y and a second position value P 2   x  of a point meeting a corner of the tray while the laser sensor scans in the horizontal direction X; a fourth step of moving the transfer unit and the laser senor to another position adjacent to another vertex of the tray in a diagonal direction and having the laser sensor scan in the horizontal and vertical directions X and Y; a fifth step of getting a third position value P 3 y of a point meeting a corner of the tray while the laser sensor scans in the vertical direction Y in the fourth step and a fourth position value P 4 x of a point meeting a corner of the tray while the laser sensor scans in the horizontal direction X in the fourth step; a sixth step of having the control unit calculate a coordinate of the transfer unit for centers of the semiconductor devices at a first row and column ( 1 ,  1 ) and a last row and column (n 2 , n 1 ) of the tray and coordinates of horizontal and vertical pitches using the first to fourth position values and the basic information of the tray; a seventh step of carrying out the second to fifth steps selectively by moving the transfer unit to one of the change kits to get position values of the charge kits; and an eighth step of having the control unit calculate a coordinate of each of the change kits for centers of the semiconductor devices at a First row and column ( 1 ,  1 ) and a last row and column (n 2 , n 1 ) of the corresponding change kit and coordinates of horizontal and vertical pitches using the position values found by the seventh step and the basic information of the change kits. 
   It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings: 
       FIG. 1  illustrates a layout of a general handler for semiconductor device test; 
       FIG. 2  illustrates a diagram for constitution and operation of an apparatus for recognizing a working position of a device transfer system in a handler according to one embodiment of the present invention; 
       FIG. 3  illustrates a layout of a tray for explaining a method of recognizing a working position for a tray of a device transfer system in a handler according to the present invention; 
       FIG. 4  illustrates a flowchart of a method of recognizing working position for a tray of a device transfer system in  FIG. 3 ; 
       FIG. 5  illustrates a layout of a change kit for explaining a method of recognizing working position for a change kit of a device transfer system in a handler according to the present invention; 
       FIG. 6  illustrates a flowchart of a method of recognizing working position for a change kit of a device transfer system in  FIG. 5 ; and 
       FIG. 7  illustrates a layout of a device transfer system for explaining an offset value between a picker of a device transfer system and an apparatus for recognizing a working position. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
   For the convenience of understanding, a constitution of a handler, to which a method of recognizing a working position of a transfer unit according to the present invention, refers to that of the handler according to the related art in FIG.  1 . 
     FIG. 2  illustrates a diagram for constitution and operation of an apparatus for recognizing a working position of a device transfer system in a handler according to one embodiment of the present invention. 
   Referring to  FIG. 2 , a laser sensor  17 , which irradiates a laser beam  17   a  downward and detects a color change of a detected object and send output signals to a controller unit (not shown), is fixedly installed in one side of a device transfer unit  15 . The laser sensor  17  scans a handler body as the pickup device moves. If the laser beam  17   a  comes into contact with such a change kit having a color different that of base plate of the handler body as a tray  200 , soaking plate  7 , and shuttles  8   a ,  8   b ,  9   a , and  9   b , an output waveform is changed to make the laser sensor  17  detect an object. 
     FIGS. 3  to  7  illustrate diagrams for explaining a method of recognizing a working position of the device transfer system according to the present invention.  FIG. 3  illustrates a layout of a tray for explaining a method of recognizing a tray working position of a transfer unit in a handler according to the present invention,  FIG. 4  illustrates a flowchart of a method of recognizing a working position of a tray in  FIG. 3 ,  FIG. 5  illustrates a layout of a change kit for explaining a method of recognizing a change kit working position of a transfer unit in a handler according to the present invention,  FIG. 6  illustrates a flowchart of a method of recognizing a working position of a change kit in  FIG. 5 , and  FIG. 7  illustrates a layout of a transfer unit for explaining an offset value between a picker of a transfer unit and an apparatus for recognizing a working position. 
   First of all, before a recognition operation of working positions of trays and change kits is carried out, species of test-expecting semiconductor devices and various kinds of basic informations of the tray and change kits are inputted to a control unit (not shown in the drawing). The informations of the tray  200  and change kits  7 ,  8   a ,  8   b ,  9   a , and  9   b , which are inputted to the control unit (not shown in the drawing) are basically provided by a manufacturer when the tray and change kits are manufactured. The informations includes sizes of the tray  200  and soaking plate  7 , and shuttles  8   a ,  8   b ,  9   a , and  9   b , a horizontal distance (M 1 , X 1 ) between an origin O and a center of a semiconductor device  100  adjacent to the origin O, a vertical distance (M 2 , Y 1 ) between an origin O and a center of a semiconductor device  100  adjacent to the origin O, a horizontal pitch (Txp, Xp) between the semiconductor devices  100 , a vertical pitch (Typ, Yp) between the semiconductor devices  100 , a count of the semiconductor devices  100 , and an offset compensating value (ΔX, ΔY) (see  FIG. 7 ) between a reference picker  15   a  of a transfer unit and a beam discharging point of the laser sensor  17 . 
   After the basic informations has been inputted to the control unit of the handler, as shown in FIG.  3  and  FIG. 4 , the device transfer unit  15  is moved to a point P 1  adjacent to one vertex as an origin of the tray  200 . The device transfer unit  15  is then moved in a negative vertical direction −Y for scanning with the laser sensor  17 . 
   If the laser beam of the laser sensor  17  comes into contact with a corner of the tray  200  while scanning, the laser sensor  17  transmits a signal of detecting the tray  200  to the control unit. The control unit then memorizes a first position value P 1 y as a coordinate of the pickup device at that point. 
   Subsequently, after the device transfer unit  15  has been moved to a point P 2 , a scan of the laser sensor  17  is carried out by moving the device transfer unit  15  in a positive horizontal direction +X to get a second position value P 2 x of one corner of the tray  200 . 
   After the device transfer unit  15  has been moved to a point P 3  adjacent to a diagonal vertex of the tray  200 , a scan of the laser sensor  17  is carried out by moving the device transfer unit  15  in a positive vertical direction +Y to get a third position value P 3 y of a corner of the tray  200 . 
   After the device transfer unit  15  has been moved to a point P 4 , a scan of the laser sensor  17  is carried out by moving the device transfer unit  15  in a negative horizontal direction −X to get a fourth position value P 4   x  of a corner of the tray  200 . 
   It is able to calculate primarily a coordinate of the device transfer unit  15  and coordinates of horizontal and vertical pitches against central points of the semiconductor devices on first row and column ( 1 , 1 ) and last row and column (N 2 , N 1 ) of the tray  200  using the above-found first to fourth position values P 1   y , P 2   x , P 3   y , and P 4   x  and the information inputted previously to the control unit such as a size of the tray, a count of the semiconductor devices  100  mounted on the tray, horizontal and vertical pitches Txp and Typ between the semiconductor devices  100 , and a distance (M, M 1 ) between the origin (O) and a center of the adjacent semiconductor device  100 . 
   For instance, a coordinate of the center of the semiconductor device on the first row and column ( 1 ,  1 ) can be found by an equation of ( 1 , 1 )±{(P 2   x +M), (P 1   y −M 1 )}. 
   Moreover, a horizontal pitch is (P 4   x -P 2   x - 2 )/(N 1 -1) and a vertical pitch is (P 1   y -P 3   y - 2 M1)/(N 2 -1). 
   Meanwhile, even if the device picking up the semiconductor device in the pickup device is practically the picker  15   a , the coordinates are found by taking the laser beam  17   a  of the laser sensor  17  as a reference. Hence, in order for the device transfer unit  15  to pick up the semiconductor devices correctly for practical use, a distance difference between the reference picker  15   a  of the device transfer unit  15  and the laser beam  17   a  discharging point needs to be compensated for the coordinates. 
   Namely, the offset compensating value (ΔX, ΔY) between the position of the reference picker  15   a  and the laser beam  17   a  discharging point of the laser sensor  17 , as shown in  FIG. 7 , is calculated on the coordinate setup to reset a final coordinate. 
   Once the recognition operation of the working position for the tray  200  is completed, the device transfer unit  15  moves to the change kits such as the soaking plate  7  (see.  FIG. 1 ) and the shuttles  8   a  and  8   b  in turn to carry out the recognition operations of working positions in a manner similar to the above-explained procedures. 
   Referring to FIG.  5  and  FIG. 6 , after the device transfer unit  15  has been moved to a point P 5  adjacent to one side vertex of the shuttle  8   a  or  8   b , the device transfer unit  15  is moved in the positive horizontal direction +X to carry out a scan of the laser sensor  17  to get a fifth position value P 5 x of a corner of the shuttle  8   a  or  8   b . After the device transfer unit  15  has been moved to a point P 6 , the device transfer unit  15  scans in the positive vertical direction +Y to get a sixth position value P 6 y of a corner of the shuttle  8   a  or  8   b.    
   After the device transfer unit  15  has been moved to a point P 7  adjacent to a diagonal vertex of the shuttle  8   a  or  8   b , the device transfer unit  15  scans in the negative horizontal direction −X to get a seventh position value P 7   x.    
   After the device transfer unit  15  has been moved to a point P 8  adjacent to a diagonal vertex of the shuttle  8   a  or  8   b , the device transfer unit  15  scans in the negative vertical direction −Y to get an eighth position value P 8   y.    
   It is able to calculate primarily a coordinate of the device transfer unit  15  and coordinates of horizontal and vertical pitches against central points of the semiconductor devices on first row and column ( 1 , 1 ) and last row and column (n, m) of the shuttle  8   a  or  8   b  using the above-found fifth to eighth position values P 5   x , P 6   y , P 7   x , and P 8   y  and the information inputted previously to the control unit such as a size of the shuttle  8   a  or  8   b , a count of the semiconductor devices  100  mounted on the shuttle  8   a  or  8   b , horizontal and vertical pitches Txp and Typ between the semiconductor devices  100 , a distance (M, M 1 ) between the origin (O) and a center of the adjacent semiconductor device  100 . 
   In this case, a coordinate of the center of the semiconductor device  100  on the first row and column ( 1 , 1 ) can be found by an equation of ( 1 , 1 )═{(P 5   x +X 1 ), (P 6   y +Y 1 )}. 
   After the coordinate has been found primarily, the coordinates of the centers of the semiconductor devices at the first row and column ( 1 , 1 ) and the last row and column (n, m) are finally calculated to reset considering the offset compensating value (ΔX, ΔY) shown in FIG.  7 . 
   Meanwhile, after the operation of recognizing the working positions of the change kits has been carried out, or preferably, before the operation of recognizing the working positions of the change kits is carried out, the device transfer unit  15  carries out an operation of scanning a shuttle ID marks  80  installed at one side of the shuttle  8   a  or  8   b  in order to check whether the change kit is properly replaced to fit with the species of the test-expecting semiconductor devices. 
   The shuttle ID marks  80  attached to the first shuttle  8   a  or  8   b  includes a plurality of holes  81  arranged to leave a predetermined interval from each other. And, each of the holes is recognized as a binary code by the laser sensor  17  to represent the species of the change kit and semiconductor device. 
   Namely, when the laser sensor  17  scans the holes  81  of the shuttle ID marks  80 , a portion having the hole  81  and another portion failing to have the hole  81  are recognized as ‘0’ and ‘1’, respectively to be transferred to the control unit. The control unit then recognizes the chance kit recognizing unit  80  by the binary codes transferred by the laser sensor  17 . 
   For instance, Table 1 shows a construction of the change kit recognizing unit and Table 2 illustrates an exemplary construction of the recognizing unit of the shuttle  8   a  or  8   b  for testing 14×20 TQFP type semiconductor devices and a shuttle information inputted to the control unit based on Table 1. The first two digits of the binary code represented by the holes  81  of the recognizing unit  80 , as shown in Table 1 and Table 2, indicates the species of the change kit, while the following eight digits represent the species of the test-expecting semiconductor device. 
   
     
       
             
             
             
           
         
             
                 
               TABLE 1 
             
             
                 
                 
             
             
                 
               Change kit species 
               Semiconductor device species 
             
             
                 
                 
             
           
           
             
                 
               2 bits 
               8 bits 
             
             
                 
               00: Soaking plate 
               00000000: 14x20 TQFP 
             
             
                 
               01: shuttle 
               10000000: 25x25 BGA 
             
             
                 
                 
             
           
        
       
     
   
   
     
       
             
             
             
             
             
             
             
           
             
             
             
             
             
             
             
           
         
             
               TABLE 2 
             
             
                 
             
             
               Change kit 
                 
                 
                 
                 
                 
                 
             
             
               recognizing 
             
             
               unit 
               X1 
               Y1 
               Xp 
               Yp 
               n 
               M 
             
             
                 
             
           
           
             
                 
             
           
        
         
             
                 
               30 
               30 
               80 
               80 
               2 
               2 
             
             
                 
                 
             
           
        
       
     
   
   Meanwhile, in the above-explained embodiments, the position values of the two points in diagonal directions of the tray and change kit are found to recognize the coordinates again. Yet, the position value of the tray or change kit can be found by selecting a random portion of four vertexes by the demand of an operator. 
   For instance, the tray and change kit may have measurement errors in their manufacturing processes. Besides, when being installed in the handler body, the tray and change kit may fail to fit the positions by the interference with the driving device to be inclined slightly. In order to carry out the recognition operation more precisely and decrease the probability of error occurrence, the position values of the entire four vertexes are preferably found to re-recognize the coordinates. It is a matter of course that this case needs a more time to recognize the working positions. 
   Accordingly, the present invention sets the working position of the transfer unit for the tray and change kit replaced by the simple construction automatically and promptly, thereby enabling to improve work efficiency as well as test productivity. 
   It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.