| 摘要 |
PURPOSE:To conduct securely a detection of the position of each wafer and a detection of the aging of the wafer carrying mechanism by a wafer position detecting device in a simple constitution by a method wherein the device is provided with a parallel shifting mechanism for the wafer optical path. CONSTITUTION:A laser beam 2 to be emitted from a laser light source 1 is made to refract by a rotating glass plate 3 to be provided as the luminous flux parallel shifting means for the laser optical path and after the course thereof is changed, the laser beam 2 is emitted by a reflecting mirror 4 in parallel to wafers 7 or a finger 5. The rotating glass plate 3 can be made to rotate toward arbitrary positions and the control unit is capable of knowing the angles to be made to rotate. A carrier stand 9 is made to shift to the upper direction higher than the position of a photosensor 8 in a state that the finger 5 is made to contract, the state between the reflecting mirror 4 and the photosensor 8 is set into such a state that a wafer alone of the wafers 7, which is placed on the finger 5, exists between them, the glass plate 3 is made to rotate, the angle of rotation at the time the output of the photosensor begins falling is memorized, the center in the thickness direction of the wafer 7 is calculated and the position of the finger 5 is calculated from the value of the center calculated. Then, the wafer 7 on the finger 5 is removed and the position of the desired wafer and the position of the wafer to be located under the lower side of the desired wafer are found out. |
