OFF-AXIS ALIGNING DEVICE FOR SCANNING TYPE PHOTOLITHOGRAPHY AND PHOTOLITHOGRAPHY TOOL

摘要

PROBLEM TO BE SOLVED: To improve the alignment precision between a wafer and a mask by providing a sub-system formed of an alignment sensor head, an alignment lighting device and an alignment detecting device. SOLUTION: This device has a lighting source 68, a reticule 32, a first lens device for directing a beam, an aperture stop 38, and a beam splitter 42. It also has second lens devices 48, 50 for directing the beam to a wafer 18 and collecting the beam reflected and scattered by the wafer 18, and the wafer 18 has plus and minus alignment marks thereon. Further, this device has a first detector device related to the beam splitter 42 for detecting the beam reflected by the wafer 18, a detector device for detecting the beam scattered from the plus alignment mark 34' on the wafer 18, and a third detector for detecting the beam scattered from the minus alignment mark 34 on the wafer 18. Thus, a more precise alignment can be attained regardless of number, thickness and layer structure characteristics.