| 摘要 |
A projection exposure system for printing the pattern formed on a reticle onto a wafer includes a reticle stage (5) and a wafer stage. A first reference plate (9) having a first reference pattern (MM1) formed thereon is mounted on the reticle stage (5), and a second reference plate (25) having a second reference pattern (WM1) formed thereon is mounted on the wafer stage. The first reference pattern (MM1) comprises two cross-marks (60a, 60b) spaced apart from each other in X-direction, and the second reference pattern (WM1) comprises two cross-marks (61a, 61b) spaced apart from each other in X-direction. Images of the cross-marks (61a, 61b) of the second reference pattern (WM1) are formed through a projection optical system (2) on the reticle stage (5) and superimposed with the cross-marks (60a, 60b) of the first reference pattern (MM1). A pair of observation optical systems (10, 11) spaced apart from each other in X-direction are used to observe the superimposed images of the corresponding cross-marks (60a and 61a, 60b and 61b), so as to determine the position shifts in X-direction between the corresponding superimposed images at two positions spaced from each other in X-direction. The determined position shifts are used to calculate the variation in projection magnification. The projection exposure system is capable of quick and high precision detection of the magnification of the projection optical system (2).
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