Abstract:
The present invention relates to a test tray for a test handler. According to this invention, there is disclosed a technique that an insert loaded in a loading part which is arranged in a matrix pattern in a frame of the test tray allows an amount and direction of free movement thereof to be determined in accordance with a location of the loading part, where the insert is loaded, on the matrix, thereby enabling a thermal expansion or contraction of a match plate or the test tray to be compensated.

Description:
This application is a Continuation Application of PCT International Application No. PCT/KR2007/000130 filed on Jan. 8, 2007, which designated the United States. 

   FIELD OF THE INVENTION 
   The present invention relates to a side-docking type test handler; and, more particularly, to a method for transferring test trays in the side-docking type test handler. 
   BACKGROUND OF THE INVENTION 
   In general, a test handler is an apparatus for assisting a tester to test semiconductor devices manufactured through predetermined manufacturing processes, and the test handler classifies the semiconductor devices by grade according to a test result. The test handler has been disclosed in several publications, e.g., Korean Patent Laid-open Publication No. 2003-0029266 entitled “Test handler”. 
   Referring to  FIG. 1 , there is shown a conceptual diagram of a conventional side-docking type test handler as viewed from above. The side-docking type test handler includes a loading unit  11 , a soak chamber  12 , a test chamber  13 , a desoak chamber  14 , and an unloading unit  15 . As illustrated in  FIG. 1 , the side-docking type test hander has a structure in which the soak chamber  12  is arranged at a back side of the loading unit  11  positioned on a left side in the test handler; the desoak chamber  14  is arranged at a back side of the unloading unit  15  positioned on a right side in the test handler; and the test chamber  13  is arranged at a back side of the soak chamber  12  and the desoak chamber  14 . 
   In the loading unit  11 , the semiconductor devices loaded on customer trays are transferred to a test tray and loaded thereon. 
   In the soak chamber  12 , the test tray is translated toward the test chamber  13 . While it is translated, the semiconductor devices loaded on the test tray are preheated or precooled depending on a preset test environment in the soak chamber  12 . 
   In the test chamber  13 , the test tray is transferred from the back side of the soak chamber  12  toward the back side of the desoak chamber  14 . When the test tray is positioned at an approximately central portion C of the test chamber  13 , the test tray is made to be closely attached to a tester  21  docked to a back side of the central portion C. Accordingly, the semiconductor devices loaded on the test tray are supplied to the tester  21  for testing (more specifically, the semiconductor devices are made to contact with contact sockets of the tester). 
   In the desoak chamber  14 , the heated or cooled semiconductor devices transferred from the test chamber  13  are restored to a room temperature. 
   In the unloading unit  15 , the semiconductor devices transferred from the desoak chamber  14  while being loaded on the test tray are classified by test grades and then transferred onto customer trays. 
   As described above, the semiconductor devices are transferred from the loading unit  11  to the unloading unit  15  via the soak chamber  12 , the test chamber  13  and the desoak chamber  14 , as indicated by an arrow a in  FIG. 1 . In this regard, the semiconductor devices are transferred from the loading unit  11  to the unloading unit  15  while being loaded on the test tray. This is because the test tray is designed to satisfy test conditions, whereas the customer tray is designed to densely load a large number of semiconductor devices so that a gap between semiconductor devices loaded on the customer tray does not satisfy the test conditions. 
   Since the semiconductor devices are transferred while being loaded on the test tray, the test tray needs to be transferred along a circulation path indicated by an arrow b beginning from the loading unit  11  and returning thereto via the soak chamber  12 , the test chamber  13 , the desoak chamber  14 , and the unloading unit  15 . The related arts of the test tray transfer method are disclosed in, e.g., Korean Patent Laid-open Publication No. 1997-0077466 entitled “TEST TRAY TRANSFER METHOD” (hereinafter, referred to as “prior art”. 
   A continuously increasing demand for semiconductor devices has led to an increase in a processing amount per unit time of the test handler. Thus, there have arisen needs to increase the number of semiconductor devices to be tested at one time and improve a processing speed of the test handler. The present invention has a purpose of increasing the number of semiconductor devices that can be tested at one time. 
   SUMMARY OF THE INVENTION 
   It is, therefore, an object of the present invention to provide a method for transferring test trays in a side-docking type test handler, wherein semiconductor devices loaded on three test trays can be concurrently tested, thereby resulting in an increase in the number of semiconductor devices that can be tested at a time. 
   In accordance with an aspect of the present invention, there is provided a method for transferring test trays in a side-docking type test handler, the method comprising the steps of: (a) transferring a test tray in a horizontal posture from a loading unit to a test chamber via a soak chamber after semiconductor devices are loaded thereon, wherein the horizontal posture of the test tray is changed to a vertical posture at a point while it is transferred; (b) vertically arranging in three rows three test trays sequentially transferred to the test chamber in the step (a); (c) transferring the three test trays vertically arranged in the three rows in the step (b) to a test position; (d) transferring each of the three test trays from the test chamber to an unloading unit via a desoak chamber after a test for semiconductor devices loaded on the three test trays is completed, wherein the vertical posture of the test tray is changed to the horizontal posture at a point while it is transferred; and (e) transferring each of the test trays transferred to the unloading unit in the step (d) to the loading unit after the semiconductor devices are unloaded therefrom. 
   The step (a) may include the steps of: (a1) transferring the test tray in the horizontal posture from the loading unit into the soak chamber; (a2) changing the horizontal posture of the test tray transferred into the soak chamber in the step (a1) to the vertical posture; (a3) lowering the test tray in the vertical posture obtained in the step (a2) downward to a predetermined position; and (a4) translating the test tray moved downward to the predetermined position in the step (a3) to the test chamber. Further, in the step (a4), the test tray is translated to a middle position of the test chamber, and in the step (b), the three test trays sequentially translated to the test chamber in the step (a4) are arranged at an upper, a lower and the middle position in that order or at the lower, the upper and the middle position in that order. Alternatively, in the step (a4), the test tray is translated to a lower position of the test chamber, and in the step (b), the three test trays sequentially translated to the test chamber in the step (a4) are arranged at an upper, a middle and the lower position in that order. 
   The step (a) may include the steps of: (a1) transferring the test tray in the horizontal posture from a loading unit into the soak chamber and arranging the test trays sequentially transferred into the soak chamber in two vertical rows, wherein the horizontal posture of the test tray is changed to the vertical posture at a point while it is transferred and arranged; and (a2) translating the test trays that have been arranged in the two vertical rows in the step (a1) to the test chamber. Further, in the step (a2), the test trays are translated to a middle position and a lower position of the test chamber, and in the step (b), among the three test trays, two test trays sequentially translated to the middle position of the test chamber are arranged at an upper and the middle position in that order and one test tray translated to the lower position of the test chamber is arranged at the lower position. Alternatively, in the step (a2), the test trays are translated to an upper and a lower position of the test chamber, and in the step (b), among the three test trays, one test tray translated to the upper position of the test chamber is arranged at the upper position and two test trays sequentially translated to the lower position of the test chamber are arranged at a middle and the lower position in that order. Substitutively, in this case, in the step (b), among the three test trays, two test trays sequentially translated to the upper position of the test chamber are arranged at a middle and the upper position in that order and one test tray translated to the lower position of the test chamber is arranged at the lower position. 
   The step (a) may includes the steps of: (a1) transferring the test tray in the horizontal posture from the loading unit into the soak chamber; (a2) translating the test tray transferred into the soak chamber in the step (a1) downward to a predetermined position; and (a3) changing the horizontal posture of the test tray to the vertical posture and transferring the test tray in the vertical posture to the test chamber. Further, in the step (a3), the test tray is transferred to a middle position of the test chamber, and in the step (b), the three test trays sequentially transferred to the test chamber in the step (a3) are arranged at an upper, a lower and the middle position in that order or at the lower, the upper and the middle position in that order. Alternatively, in the step (a3), the test tray is transferred to a lower position of the test chamber, and in the step (b), the three test trays sequentially transferred to the test chamber in the step (a3) are arranged at an upper, a middle and the lower position in that order. 
   In accordance with the present invention, the test handler can assist a tester to test semiconductor devices loaded on three test trays concurrently, thereby resulting in an increase in the number of semiconductor devices that can be tested at a time. Accordingly, a processing speed of the test handler is improved. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects and features of the present invention will become apparent from the following description of preferred embodiments, given in conjunction with the accompanying drawings, in which: 
       FIG. 1  is a top view showing a transfer path of semiconductor devices and a test tray in a general side-docking type test handler; 
       FIG. 2  provides a flowchart of a method for transferring test trays in a side-docking type test handler in accordance with a first preferred embodiment of the present invention; 
       FIGS. 3 to 6B  present diagrams for explaining the test tray transfer method of  FIG. 2 ; 
       FIG. 7  represents a flowchart of a method for transferring test trays in a side-docking type test handler in accordance with a second preferred embodiment of the present invention; 
       FIGS. 8 to 10B  offer diagrams for explaining the test tray transfer method of  FIG. 7 ; 
       FIG. 11  is a flowchart of a method for transferring test trays in a side-docking type test handler in accordance with a third preferred embodiment of the present invention; and 
       FIGS. 12 and 13  depict diagrams for explaining the test tray transfer method of  FIG. 11 . 
   

   DETAILED DESCRIPTION OF THE EMBODIMENTS 
   Hereinafter, test tray transfer methods in a side-docking type test handler in accordance with preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
   First Preferred Embodiment 
     FIG. 2  shows a flowchart of a method for transferring test trays in a side-docking type test handler in accordance with a first preferred embodiment of the present invention.  FIG. 3  is a conceptual diagram illustrating a state where the test trays are transferred in the side-docking type test handler in accordance with the test tray transfer method of  FIG. 2 . Hereinafter, the test tray transfer method in accordance with the first preferred embodiment of the present invention will be described with reference to  FIGS. 2 and 3 . 
   After semiconductor devices are loaded onto a test tray  201  positioned in a loading unit, the test tray in a horizontal posture is transferred into a soak chamber  220  (step S 201 ). 
   Next, the horizontal posture of the test tray that has been transferred into the soak chamber  220  in the step S 201  is changed to a vertical posture (step S 202 ). 
   The steps S 201  and S 202  have been disclosed in Korean Patent Application No. 10-2005-0124223 (Korean Patent No. 10-074106) entitled “Test handler and an operation method thereof”, which had been previously filed by the present applicant. In this method, it is possible to reduce time required for testing semiconductor devices since the semiconductor devices loaded on the test tray are preheated or precooled even while the posture of the test tray is changed unlike the prior art. 
   Thereafter, the test tray in the vertical posture obtained in the step S 202  is lowered to a predetermined position (step S 203 ). Herein, the predetermined position approximately corresponds to a middle position of the test chamber  230  in a vertical direction. 
   The test tray, moved downward to the predetermined position in the step S 203 , is translated backward step by step to finally reach the middle position of the test chamber  230  (step S 204 ). As can be seen from  FIG. 3 , the test tray translated to the test chamber  230  from the soak chamber  220  is located at a left side in the test chamber  230 . 
   Three test trays that have been sequentially translated to the middle position of the test chamber  230  in the step S 204  are arranged vertically in three rows, i.e., at an upper, a lower and the middle position in that order (step S 205 ). This will be described in detail with reference to  FIGS. 4A to 4D . 
     FIGS. 4A to 4D  are left side views of the test tray transfer state as shown in  FIG. 3 , in which three test trays are illustrated in bold for convenience of explanation. As illustrated in  FIGS. 4A and 4B , the test trays preheated or precooled in the soak chamber  220  are translated step by step to finally reach the test chamber  230 . At this time, a test tray  202  first arrived at the middle position of the test chamber  230  is lifted to the upper position of the test chamber  230  as shown in  FIG. 4C . A test tray  203  secondly arrived at the middle position of the test chamber  230  is lowered to the lower position of the test chamber  230  as illustrated in  FIG. 4D . Then, a test tray  204  is thirdly arrived at the middle position as shown in  FIG. 4D . Consequently, the three test trays sequentially translated from the soak chamber  220  to the test chamber  230  are arranged vertically in three rows. Alternatively, the three test trays may be arranged vertically at the lower, the upper and the middle position in that order. 
   Next, the three test trays arranged vertically in the three rows in the step S 205  are transferred to a test position corresponding to a central portion of the test chamber  230  (step S 206 ). 
   Thereafter, the semiconductor devices loaded on the three test trays are tested in the test position corresponding to the central portion of the test chamber  230  in the step S 206 , and the three test trays are then transferred to a right side in the test chamber  230 , i.e., to a back side of the desoak chamber  240  (step S 207 ). 
   Among the three test trays transferred to the back side of the desoak chamber  240  in the step S 207 , the test tray at the middle position is transferred forward to the desoak chamber  240  and the test trays at the upper and lower position are sequentially transferred to the middle position and then transferred to the desoak chamber  240 . Consequently, the test trays arranged vertically in the three rows are sequentially transferred to the desoak chamber  240  (step S 208 ). Alternatively, the test trays at the lower and the upper position are sequentially transferred to the middle position and then transferred to the desoak chamber  240 . 
   Next, the test tray transferred from the test chamber  230  to the desoak chamber  240  in the step S 208  is translated forward to a predetermined position step by step (step S 209 ). 
   Then, the test tray translated to the predetermined position in the step S 209  is lifted upward to a prearranged position (step S 210 ). 
   Thereafter, the vertical posture of the test tray lifted upward is changed to the horizontal posture (step S 211 ). 
   The test tray in the horizontal posture obtained in the step S 211  is transferred to the unloading unit, so that it is disposed as indicated by reference numeral  205  (step S 212 ). 
   After the semiconductor devices are unloaded from the test tray transferred to the unloading unit in the step S 212 , the test tray is then transferred to the loading unit, so that it is disposed as indicated by reference numeral  201 . 
   (Modification of the First Preferred Embodiment) 
     FIG. 5  shows a modification of the first preferred embodiment. Referring to  FIG. 5 , in case the test tray transferred from the loading unit into the soak chamber  220   a  is lowered to a predetermined position after its horizontal posture is changed to the vertical posture, the test tray is lowered to a position corresponding to the lower position of the test chamber  230   a  in the vertical direction and then translated to the lower position of the test chamber  230   a . Accordingly, the test tray is transferred to the lower position of the test chamber  230   a  from the soak chamber  220   a . In this case, the three test trays sequentially translated to the test chamber  230   a  are arranged vertically at the upper, the middle and the lower position in that order. When the test trays are transferred from the test chamber  230   a  to the desoak chamber  240   a , they are preferably transferred in the order of the trays at the lower, the middle and the upper position. 
   The first preferred embodiment shown in  FIG. 3  and the modification thereof shown in  FIG. 5  are different from each other in time required for vertically arranging three test trays in three rows. Referring to  FIG. 6A , in case of the first preferred embodiment shown in  FIG. 3 , a total moving distance required to vertically arrange three test trays in three rows corresponds to 2L. However, referring to  FIG. 6B , in case of the modification shown in  FIG. 5 , a total moving distance required to vertically arrange three test trays in three rows corresponds to 3L (this is true when the test trays are transferred from the test chamber to the desoak chamber). The difference in the moving distance is related to the time for vertically arranging the test trays in three rows, so that a processing speed of the test handler increases in case of employing the transfer method of  FIG. 3 . 
   Second Preferred Embodiment 
     FIG. 7  presents a flowchart of a test tray transfer method in accordance with a second preferred embodiment of the present invention.  FIG. 8  represents a conceptual diagram of a side-docking type test handler employing the transfer method of  FIG. 7 . Hereinafter, the test tray transfer method in accordance with the second preferred embodiment of the present invention will be described with reference to  FIGS. 7 and 8 . 
   After semiconductor devices are loaded onto a test tray  701  positioned in a loading unit, the test tray in a horizontal posture is transferred into a soak chamber  720  (step S 701 ). 
   Next, the horizontal posture of the test tray transferred into the soak chamber  220  in the step S 701  is changed to a vertical posture (step S 702 ). 
   Thereafter, the test trays in the vertical posture sequentially obtained in the step S 702  are lowered and arranged in two vertical rows, i.e., an upper and a lower row (step S 703 ). Herein, the positions of the test trays arranged in the two rows approximately correspond to a middle and a lower position of the test chamber  730  in a vertical direction. 
   The test trays arranged in the two vertical rows in the step S 703  are translated backward step by step to finally reach the middle and the lower position of the test chamber  730  (step S 704 ). 
   The test tray translated to the lower position of the test chamber  730  in the step S 704  is maintained at the lower position. Further, two test trays sequentially translated to the middle position are arranged at an upper and the middle position in the order of transfer. Consequently, the three test trays translated from the soak chamber  720  to the test chamber  730  are arranged vertically in three rows in the test chamber  730  (step s 705 ). To that end, the number of the test trays translated from the soak chamber  720  to the middle position of the test chamber  730  is required to be twice the number of the test trays translated from the soak chamber  720  to the lower position of the test chamber  730 , and the test trays whose postures are changed in the step S 702  need to be arranged in the two rows in the step S 703  in a suitable manner to the above requirement. 
   Next, the three test trays arranged in the three rows in the step S 705  are transferred to a test position corresponding to a central portion of the test chamber  730  (step S 706 ). 
   Thereafter, the semiconductor devices loaded on the three test trays are tested in the test position corresponding to the central portion of the test chamber  230  in the step S 706 , and the three test trays are then transferred to a right side in the test chamber  730 , i.e., to a back side of a desoak chamber  740  (step S 707 ). 
   Among the three test trays transferred to the back side of the desoak chamber  740  in the step S 707 , the test trays at the middle and the lower position are transferred to the desoak chamber  740  as they are, and the test tray at the upper position is lowered to the middle position and then transferred to the desoak chamber  240  (step S 708 ). Accordingly, the test trays can be translated forward in a state where they are arranged in two rows in the desoak chamber  740 . 
   Next, the test trays transferred in the two rows from the test chamber  230  to the desoak chamber  240  in the step S 708  are translated forward to a predetermined position step by step (step S 709 ). 
   Then, the test tray translated forward to the predetermined position in the step S 709  is lifted upward to a prearranged position (step S 710 ). 
   Thereafter, the vertical posture of the test tray lifted upward in the step S 710  is changed to the horizontal posture (step S 711 ). 
   The test tray in the horizontal posture obtained in the step S 711  is transferred to an unloading unit, so that it is disposed as indicated by reference numeral  705  (step S 712 ). 
   After the semiconductor devices are unloaded from the test tray transferred to the unloading unit in the step S 712 , the test tray is transferred to the loading unit, so that it is disposed as indicated by reference numeral  701  (step S 713 ). 
   In accordance with the second preferred embodiment, it is possible to further reduce the time required to vertically arrange the test trays in three rows in the test chamber  730 . Therefore, a higher processing speed can be realized in comparison with the first preferred embodiment and the modification thereof. 
   Although the horizontal posture of the test tray in the second preferred embodiment is changed to the vertical posture in the soak chamber  720 , the test tray may be transferred into the soak chamber after its posture is changed to the vertical posture above the soak chamber as in the prior art. 
   (Modification of the Second Preferred Embodiment) 
     FIG. 9  describes a modification of the second preferred embodiment. Referring to  FIG. 9 , positions of a loading unit and an unloading unit correspond to a middle position of a test chamber  730   a  in a vertical direction. Further, respective positions where the test trays change the posture thereof in a soak chamber  720   a  and a desoak chamber  740   a  correspond to the middle position of the test chamber  730   a  in a vertical direction. 
   In case the test trays sequentially transferred from the loading unit into the soak chamber  720   a  are arranged in two rows after changing their horizontal posture to the vertical posture, the positions of the test trays arranged in the two vertical rows approximately correspond to an upper position and a lower position of the test chamber  730   a  in the vertical direction. The test trays arranged in the two rows are translated backward step by step to finally reach the upper and the lower position of the test chamber  730   a . The test tray translated to the upper position of the test chamber  730   a  is maintained at the upper position. Further, two test trays sequentially translated to the lower position are arranged at the middle and the lower position in the order of transfer. Consequently, the three test trays translated from the soak chamber  720   a  to the test chamber  730   a  are arranged vertically in three rows in the test chamber  730   a . To that end, the number of the test trays translated from the soak chamber  720   a  to the lower position of the test chamber  730   a  is required to be twice the number of the test trays translated from the soak chamber  720   a  to the upper position of the test chamber  730   a , and the test trays in the vertical posture need to be appropriately arranged in the two rows in a suitable manner to the requirement. Among the three test trays transferred to a back side of the desoak chamber  740   a , the test trays at the upper and the lower position are transferred to the desoak chamber  740   a  as they are, and the test tray at the middle position is lowered to the lower position and then transferred to the desoak chamber  240   a . Accordingly, the test trays can be translated forward in a state where they are arranged in two rows in the desoak chamber  740   a.    
   The second preferred embodiment shown in  FIG. 8  and the modification thereof shown in  FIG. 9  are different from each other in time required for arranging test trays in two vertical rows. Referring to  FIG. 10A , a total moving distance for arranging three test trays  701  in two rows corresponds to 4L in the second preferred embodiment of  FIG. 8 . Meanwhile, referring to  FIG. 10B , a total moving distance for arranging three test tray  701   a  in two rows corresponds to 3L in the modification of  FIG. 9  (this is true when the test trays are transferred from the desoak chamber to the unloading unit). The difference in the moving distance is related to the time for arranging test trays in two rows, so that a processing speed of the test handler increases in case of employing the transfer method of  FIG. 9 . 
   In case the test trays are arranged in two rows corresponding to the upper and the lower position of the test chamber, it is also possible that two test trays sequentially translated to the upper position of the test chamber are arranged at the middle and the upper position in the order of transfer and, further, the test tray translated to the lower position is maintained at the same position. Accordingly, the three test trays translated from the soak chamber to the test chamber are arranged vertically in three rows in the test chamber. Thereafter, the test trays in the three rows at a back side of the desoak chamber are arranged in two rows through a reverse process of the above and then translated in the desoak chamber. 
   Third Preferred Embodiment 
     FIG. 11  provides a flowchart of a test tray transfer method in accordance with a third preferred embodiment of the present invention.  FIG. 12  presents a conceptual diagram showing a transfer state of test trays in a side-docking type test handler employing the transfer method of  FIG. 11 . Hereinafter, the test tray transfer method in accordance with the third preferred embodiment of the present invention will be described with reference to  FIGS. 11 and 12 . 
   After semiconductor devices are loaded onto a test tray  1101  positioned in a loading unit, the test tray in a horizontal posture is transferred into a soak chamber  1120  (step S 1101 ). 
   Next, the horizontal test tray transferred into the soak chamber  1120  in the step S 1101  is translated downward to a predetermined position (step S 1102 ). 
   Thereafter, the test tray translated downward to the predetermined position in the step S 1102  is transferred to a test chamber  1130  while changing its horizontal posture to a vertical posture (step S 1103 ). Referring to  FIG. 12 , the test tray transferred to the test chamber  1130  from the soak chamber  1120  while changing its posture is transferred approximately to a middle position of the test chamber  1130  in a vertical direction. 
   The test tray transfer method in accordance with the steps S 1101  and S 1102  has been disclosed in Korean Patent Application No. 10-2006-0028191 entitled Method for transferring test trays in a side-docking type test handler which had been previously filed by the present applicant. In accordance with this method, the test tray transferred into the soak chamber is lowered downward in the horizontal posture and its posture is then changed to the vertical, so that there are obtained a shortened circulation path of the test tray, a reduced size of the test handler and the like in comparison with the prior art. 
   The test trays sequentially transferred to the middle position of the test chamber  1130  in the step S 1103  are arranged in three rows, i.e., an upper, a lower and the middle position in that order (step S 1104 ). Alternatively, the three test trays may be arranged at the lower, the upper and the middle position in that order. 
   Next, the three test trays arranged in the three vertical rows in the step S 1104  are transferred to a test position corresponding to a central portion of the test chamber  1130  (step S 1105 ). 
   After completing the test for the semiconductor devices loaded on the three test trays located at the test position corresponding to the central portion of the test chamber  1130  in the step S 1105 , the three test trays are then transferred to a right side in the test chamber  1130 , i.e., to a back side of the desoak chamber  1140  (step S 1106 ). 
   Among the three test trays transferred to the back side of the desoak chamber  1140  in the step S 1106 , the test tray at the middle position is transferred to the desoak chamber  1140  while its vertical posture is changed to the horizontal posture and, then, the test trays at the upper and the lower position are moved to the middle position and then transferred to the desoak chamber  240  while changing their postures in that order or a reverse order. As a result, the test trays arranged in three rows are transferred to the desoak chamber  1140  while changing their vertical postures to the horizontal postures (step S 1107 ). 
   Next, the test tray transferred from the test chamber  1130  to the desoak chamber  1140  while changing its posture in the step S 1107  is translated upward to a predetermined position step by step (step S 1108 ). 
   Then, the test tray translated upward to the predetermined position in the step S 1108  is transferred to an unloading unit, so that it is disposed as indicated by reference numeral  1105  (step S 1109 ). 
   After the semiconductor devices are unloaded from the test tray transferred to the unloading unit in the step S 1109 , the test tray is transferred to the loading unit, so that is disposed as indicated by reference numeral  1101  (step S 1110 ). 
   (Modification of the Third Preferred Embodiment) 
     FIG. 13  describes a modification of the third preferred embodiment. Referring to  FIG. 13 , in case a test tray translated downward to a predetermined position is transferred from a soak chamber  1120   a  to a test chamber  1130   a  while changing its posture, the test tray is transferred to a lower position of the test chamber  1130   a  in a vertical direction. At this time, the three test trays sequentially transferred to the test chamber  1130   a  are arranged in three rows, i.e., an upper, an middle and the lower position in that order. This is true when test trays are transferred from the test chamber  1130   a  to a desoak chamber  1140   a.    
   Although the transfers in the soak chamber and the desoak chamber are made to be symmetrical to each other in the aforementioned embodiments as in a conventional method, the transfers in the soak chamber and the desoak chamber can be made differently to each other as desired. 
   The test tray transfer method described above can be variously modified without departing the scope of the present invention. Accordingly, while the invention has been shown and described in detail with respect to the preferred embodiments, the present invention is not limited thereto and the scope of the present invention should be interpreted by using the following claims and equivalents thereof.