More robust alignment mark design

摘要

Robust alignment marks which are substantially resistant to degradation caused by semiconductor device fabrication steps are disclosed. The new alignment marks use a series of geometrical shapes that are staggered in respect to each other to achieve more left and right edges providing a checkerboard alignment mark. The geometrical shapes have a size that is selected so as to be within the resolving capability of the exposure tool, yet smaller than the resolving capability of the alignment system. The small staggered geometrical shapes provide a more symmetrical signal which is more resistant to variability in prior processing steps than the standard mark design.