| 摘要 |
PURPOSE:To position always the electron beam to a prescribed position on a pattern accurately by deflecting the electron beam in not only the main scanning direction but also the subscanning direction and by repeating deflection scanning until a mark is detected. CONSTITUTION:The position designation command to read specific information in the pattern is coded by position designating circuits 29 and 30 respectively, and these signals are stored in shift registers 1 and 2. The pulse signal from oscillator 31 is sent to register 11 successively, and the number of pulses is added cumulatively and is added to the output of register 1 through adder 3, and the increment signal is applied to horizontal deflecting circuit 17 to deflect the electron beam in the X direction. The signal obtained by dividing the output of oscillator 31 by frequency divider 32 is subjected to D/A conversion in 6 through shift register 28 and adder 26 and is given to vertical deflecting circuit 18 simultaneously with the Y-direction deflection signal. Thus, the electron beam is deflected gradually in the Y direction. Deflection scanning for line and column mark position detection is repeated in this manner, thereby positioning correspondingly to designation information. |
