| 摘要 |
PROBLEM TO BE SOLVED: To provide an edge detector for simply and accurately detecting edge positions in a protection film and a wafer on a to-be-detected object comprising the wafer attached to the protection film on a surface. SOLUTION: The to-be-detected object is transmissively illuminated, and imaged by a line sensor through an imaging optical system. An output level of the line sensor is discriminated by a predetermined threshold value. The edge position of the to-be-detected object is detected in the direction of a pixel cell array in the line sensor. A gain and/or a bias of an output signal read from the line sensor are variably set. A level of the output signal whose gain and/or the bias are variably set is discriminated by a plurality of different threshold values. The edge positions at a plurality of locations (the protection film and the wafer) in the to-be-detected object are detected in parallel. COPYRIGHT: (C)2008,JPO&INPIT |
