High-order stitching overlay analysis for advanced process control

In recent years, layer-to-layer overlay methods moved from the linear regime into non-linear high-order methods in order to meet the shrinking overlay requirements. In this study we investigate a large number of metrology structures in the overlapped scribe-line between adjacent scanner fields and the opportunity for improved overlay performance. Sampling and modeling considerations are discussed. In this investigation we consider the opportunities for high-order stitching analysis in process control and scanner monitoring. The goal of this work is to establish a systematic methodology for high order stitching to characterize and reduce overlay errors for advanced IC manufacturing.