| 摘要 |
<p>PURPOSE:To detect correctly a substrate and to make it possible to reduce the generation of the erroneous operation of a device by a method wherein a substrate is irradiated with a light beam in such a way that the light beam intersect obliquely the substrate to detect the substrate, and when the result of the detection of the substrate is unclear, the incident angle of the light beam is modified and the substrate is again detected. CONSTITUTION:A cassette placing stage 13 is moved in such a way as to pass through between a light-emitting element 15 and a photodetector 16 and a scanning for detecting semiconductor wafers 11 is performed. Information obtained by the above scanning is stored in a memory or the like and a carrying-in and a carrying-out of the wafers 11 are carried out according to this information. for example, in the case of a semiconductor wafer 11a of a small diameter, as the wafer 11a can not be detected between the positions (a) and (b) of a light beam 14 in the state as the angle of the light beam is (theta), a support member 17 is rotated at a prescribed angle and the angle which is made by the beam 14 with the surface of the wafer 11a is modified from the (theta) to (theta1) according to the diameter of the wafer 11a. When the incident angle of the beam 14 is modified according to a wafer diameter, the wafers 11 can be detected at the optimum beam angle to the wafers 11 of all diameters.</p> |
