| 摘要 |
PURPOSE:To make it possible to check simply a change in the magnification of a projection optical system and thereby to enable the execution of stable and highly- accurate superposed exposure by a method wherein a remaining rotational error of a mask within a plane parallel to an image formation plane is detected after the alignment of the mask is executed, and an amount of variation is calculated as the one corresponding to an amount of variation in the image formation characteristic of an alignment optical system at the time when the center of detection of a mark is set. CONSTITUTION:First a reticle R is put on a reticle stage 2, driving units 5 and 7 is subjected to servo control so that the center 16a of detection and reference marks 30x and 30y be superposed. Then the coordinate values of xy stages 6 and 8 are read from laser interferometers 12 and 14 and memorized. The centers 16a and 17a of detection are set accurately in relation to the coordinate systems xy of the xy stages 6 and 8. The reticle R is aligned accurately with the coordinate systems xy of the xy stages 6 and 8. As to reticle rotation DELTAthetar, an amount DELTARR of deviation of a mark Sy in the direction (y) from the axis (x) is measured as an amount of the rotation. It is determined whether the amount DELTARR of the rotation is substantially zero or not. When DELTARR is large, a magnification error DELTAM is calculated, and the above opera tion is repeated again. |
