| 摘要 |
PURPOSE:To enable a mark to be detected correctly, by slightly deviating a beam for scanning over the mark toward the direction vertical to the beam scanning direction. CONSTITUTION:A microprocessor 5 gives beam scanning conditions to an X/Y scanner 6 such that the X/Y scanner scans horizontally over a mark MK. The X/Y scanner 6 outputs a scan signal scanning along the X axis to an X/Y modulator 8 via a D/A converter 7. The X/Y modulator 8 modulates the X-axis scan signal with a micro signal for slightly deviating the electron beam toward the Y-axis and outputs to a deflector 3. The deflector 3, which receives the modulated signal from the X/Y modulator 8, scanns the electron beam. Thereby, the electron beam deviated a little toward the Y axis is allowed to have a spread scanning area and to be applied to the mark MK with a longer trace. Accordingly, any defect or contaminant in the MK mark can be detected with high reliability. |
