| 摘要 |
PURPOSE:To improve the relative alignment precision by a method wherein an alignment mark on a wafer is illuminated with light with wavelength distant exceeding 50mum from that of exposing illumination light while the reflected diffractive light thereof is image-formed on an alignment mark of a mask. CONSTITUTION:A wafer mark 22 is illuminated with the light emitted from an illumination system 11 for alignment passing through a half mirror 12 and a projection lens 3. The reflected diffractive light passing through the projection lens 3 and the half mirror 12 further through turning up mirrors 13a, 13b and a light polarizing mechanism 14 reaches the position above a mask mark 21 to form the image of wafer mark 22 thereon. The wavelength of alignment light at this time is distant exceeding 50mum from that of exposing illumination light so that any slip of image-formed positions due to the difference in wavelength may be corrected by the turning up mirrors 13a, 13b. Through these procedures, the light from mark 21 can be detected by a photoelectric detector 16 through another mirror 15 to transmit any position slip signals from a signal processing circuit 17. |
