There are different approaches for alignment sampling optimization. In order to determine, which approach is optimal, OPAL run-to-run simulations1 must be executed using the result of the different sampling optimization. This means that there is a two-step approach: first, an iterative sampling optimization algorithm that results in optimal overlay modeling. Then, a run-to-run simulation is done to verify the impact on the overlay performance.
In this study, we investigate on the behavior of four different approaches to alignment sampling optimization on four different layers and analyze which approach is most suitable for which layer.