| 摘要 |
PURPOSE:To realize higly accurate positioning with a simplified structure by providing a first reflecting material in the opposite side of the projection objective and an inclined second reflecting material in the same side thereof, thereby reflecting the light beam transmitting the pattern surface of reticule, and by observing or measuring reflected light beam which transmits again the pattern surface. CONSTITUTION:A reflector M1 is arranged at the upper part of reticule R, mamely in the opposite side of projection objective L10 and an inclined reflector M2 is provided in the side of projection objective L10. A light beam 20 sent from the alignment mark Ra' on the wafer W and is irradiated to the projection objective L10 passes the reticule pattern surface Rp and is then reflected by the reflector M1 and again passes the reticule pattern surface Rp and again reflected in such a direction as becoming far from the light axis A1 by the refelctor M2. A picture of alignment mark Ra' on the wafer W is also focused at the position of the alignment mark Ra'' and a positional relation between the wafer W and reticule R can be observed from the picture positions of them. |
