PURPOSE: To prevent the wafers picked up and contained from being stained by a method wherein wafers in wafer cassette are processed successively from the bottom one to the upper ones.
CONSTITUTION: The position of centering hand CH i.e. the position of delivery or recovery and the position of bottom wafer WF1 are almost aligned with each other to pick up and contain the wafers at the position nearest to the position wherein overall scanning for detecting wafer positions is finished. In such a case, the upper wafers are not stained by means of processing the wafers from the bottom one to the upper ones. When the delivery or recovery of wafers is set up at the position near the wafer WF2 in the central position i.e. almost the intermediate position of wafer cassette, the total distance of vertical movement of finger FG can be reduced to be optimum.
HIRAGA RYOZO
SEKI MITSUAKI
