| 摘要 |
PURPOSE:To detect the position of a wafer accurately, by providing photosensors, which detect laser light inputted to a glass rod, on the upper and lower sides of the glass rod. CONSTITUTION:The basic structure of a wafer-position detecting mechanism is composed of a laser source 16; a glass rod, which is arranged at the back side of a cassette 6; a mirror 17, which reflects the laser light 20 emitted from the laser source 16 to the glass rod 18; and photosensors 19 and 19',which detect the inputted laser light to the glass rod. When, e.g., a wafer hand 5 moves from the upper side to the lower side and the wafer is located at the part between them, the laser light 20 is shielded by the wafer and not inputted to the rod 18. The sensor does not detect the light. When the wafer is not present, the photosensor 19 detects the light inputted to the rod 18. Therefore, the position, where the detected light has the least value, is the central position of the wafer. |
