| 摘要 |
PURPOSE:To compute the rotary angle of a wafer even if a semiconductor element becomes small by setting three or more scanning lines on a rectangular windows at accepting images, removing the maximum value or the minimum value among the detecting positions of the boundary lines on these scanning lines, and obtaining the average value. CONSTITUTION:At respective windows 2 in accepting regions A and B of a semiconductor element 10 formed on a wafer 1, the position of a boundary line 11 on each window 2 is detected. At this time, three or more scanning lines in the direction approximately perpendicular to the displayed boundary line are set at a constant interval. Then, the change of the level of the image signal on the scanning line at each preset scanning line is cheked. Thereafter, the coordinate values on the detecting positions (a)-(i) on each scanning line are compared. The maximum value or the minimum value is removed, and the average value is obtained. Then, the rotary angle of the wafer 1 is obtained by a trigonometric function by using the respective coordinate values of the detected positions obtained in the respective accepting regions A and B. |
