Detecting wafer scanner translation fault in photo-lithographic structuring of semiconductor wafer, especially with RAM component, by forming overlay targets in illumination fields and detemining displacement

摘要

Detection of a translation fault of a wafer scanner in the photo-lithographic structuring of a semiconductor wafer is based on illumination of a resist on the wafer in three illumination fields in specific scanning directions; forming first and second partial structures in each field by photolithographic structuring, such that overlay targets are formed in the second field; and determining the displacement of the partial structures of the overlay targets in the second field. Detection of a translation fault of a wafer scanner in the photo-lithographic structuring of a semiconductor wafer involves: (1) providing a semiconductor wafer with a substrate; (2) applying a resist; (3) aligning the wafer relative to a wafer scanner for illuminating the resist; (4) illuminating the resist with the scanner in a first illumination field (10) in a first scanning direction (24), in a second illumination field (20) in a second scanning direction (26) (opposite to the first scanning direction) and in a third illumination field (10) in the first scanning direction (24); (5) forming a first partial structure (12,12',12'') and a second partial structure (14,14',14'') in each illumination field by photolithographic structuring, such that (a) the first partial structure (12) in the first field and the second partial structure (14') in the second field together form an overlay target (28,32) in the second field (20) and (b) the first partial structure (12'') in the third field and the second partial structure (14') in the second field together form another overlay target (30,34) in the second field; (6) determining the displacement of the partial structures of the overlay targets in the second field; and (7) assessing the translation errors from the values of the displacements.