Abstract: A semiconductor wafer placed on a table is rotated by a stepper motor stepwise by a broad pitch. At this time, a CCD line sensor transmits output signals to comparators. A CPU monitors output signals of the comparators and detects a notch formed in the wafer. After the notch is detected, the wafer is rotated stepwise by a fine pitch, and outer peripheral positional data of a notched region (outputs of an analog-to-digital converter) are sampled and stored in a RAM. The CPU computes a notch position from the outer peripheral positional data stored in the RAM. In this way, a V-shaped notch formed in a semiconductor wafer is detected speedily and with high precision.

Abstract: Cutout mask data is easily obtained while setting small unit areas in an original image and displaying them in order on a display unit. Unit areas including vertexes of an outline of a cutout mask are first designated. Unit area images within the unit areas are simultaneously displayed on a display unit. An operator sequentially designates positions of the vertexes while watching the unit area images arrayed in order of the designation. Cutout mask data are formed on the basis of the positions of the vertexes.