| 摘要 |
PURPOSE:To prevent the deterioration of mark quality by inclining part or the whole of a photodetecting surface of a mask with regard to the optical axis of laser focusing light and setting the angle of inclination in such a manner that the light reflected from the photodetecting surface of the mask is not irradiated to a field lens. CONSTITUTION:The mask 13 is installed between the field lens 2 and a condenser lens 4 so as to incline with regard to the optical axis of the focusing light Lf. The mark pattern is formed to the shape which looks normal when viewed from the optical axis direction according to the angle of inclination is this stage. The angle of inclination is so set that the reflected light Lr when the light Lf is irradiated to the photodetecting surface of the mask 13 deviates toward the outside of the field lens 2. The erosion of the field lens by the reflected light Lr is thereby eliminated and the deterioration of the mark quality is prevented. |
