| 摘要 |
<p>A multi-station step-and-repeat apparatus (stepper) for imaging semiconductor wafers (114,114',116). The stepper (300) has at least 2 stations (106,106',108), at least one (108) of which is for imaging. The second station (106) may be used for image field characterization, or image defect correction, or for phase shift mask (PSM) loop cutting. Multiple laser beams (310-326') directed in orthogonal directions provide interferometric monitoring to track wafer locations for wafers on the stepper. <IMAGE></p> |
