Introduction of new techniques for matching overlay enhancement

This paper discusses two new techniques that have been developed to improve overlay matching accuracy over multiple wafer scanners: Super Distortion Matching system (SDM) and Grid Compensation for Matching (GCM), and actual data from experiments performed using the techniques. Overlay matching errors can be divided into the two basic categories, intra-shot error and inter-shot error, which can be improved by SDM and GCM, respectively.