Multi-pitch vernier for checking alignment accuracy

摘要

A vernier having multi-pitch for checking alignment accuracy. The vernier has the same pitch as the line width of the IC pattern where the diffraction angle of the vernier is the same as that of the IC pattern. The pitch comprises slits which cannot produce image on the wafer, such that a simultaneous pattern with the conventional pattern on the wafer is formed. Accordingly, the alignment accuracy can be accurately checked, thereby monitoring the alignment of IC patterns.