| 摘要 |
PURPOSE:To detect minute foreign matter at a high speed without omission, by irradiating a wafer with almost parallel laser beam from an inclined direction and continuously arranging light receiving parts, which receive light reflected and scattered from the wafer, in the arrangement direction to perform output in parallel. CONSTITUTION:The picture elements 20a of a solid image pick-up element array 20 are arranged so as to be overlapped in the arrangement direction in such a state that insensitive parts 20b are inclined to a large extent. By this arrangement, overlooking can be avoided. In this case, it is necessary to set quantity of inclination to a degree equal to or more than the size of small foreign matter 3c to be detected. The small foreign matter 3c is avoided from double-counting by picture elements (j), (k). |
