WAFER DETECTOR FOR ROTARY WAFER PROCESSOR

摘要

PURPOSE:To accurately detect a wafer on a table irrespective of the type of the wafer and a difference of processing modes. CONSTITUTION:A table 2 for placing a wafer in a state for controlling horizontal movement of an outer peripheral edge of the wafer is rotatable around a vertical shaft core P, a high reflection are 6a and a low reflection area 6b having different reflectivities in a rotating direction are formed on an upper surface of the plate 2, and a light source 7 for projecting an optical beam to the areas 6a, 6b and a light receiver 8 for receiving the beam reflected on the area 6a or 6b and outputting a light reception signal are provided at upper positions on the plate 2. The reflected states from the areas 6a, 6b are sensed by a controller 15 based on the signal from the receiver 8 to decide presence or absence of the wafer.