| 摘要 |
PURPOSE:To realize the stable mark detection by a method wherein a capacitor, which composes a processing means of a mark wave signal produced by an electron beam reflected on the mark, is put in a closed circuit while a drawn pattern is exposed and is put in an open circuit while the mark is detected. CONSTITUTION:During a drawing period, a switch S is ON. At this state, the voltage of an output line 11 is O V. During a mark detection period, an electron beam is cut off and the position of the electron beam is transferred to the neighborhood where the mark exists. At that state, the offset voltage of a detector 6 is applied to both ends of a capacitor C. At the time Tm, the switch S is OFF and a wafer is irradiated and scanned by the electron beam whose intensity is high enough to detect the mark. At this state, a mark wave on the output line 11 is stable and is put into a processor 8. This signal is binarized by a slice level setting circuit 14 and the edge part of the mark is detected and the signal is put out on the output line 11. |
