Study of the mask topography effect on the OPC modeling of hole patterns

Recently, there have been many studies on the mask topography effect on patterning. Most of existing papers report generally focused on the difference of the aerial image between the thin mask approximation and the rigorous topographic mask models. In this paper, the mask topography effect was analyzed from an OPC modeling perspective. We compared the accuracy of two types of the virtual OPC model of contact patterns that one model used the virtual test patterns generated by the lithography simulator based on the thin mask approximation model and the virtual test patterns of another model were made by the rigorous topographic mask simulation based on FDTD (Finite Difference Time Domain) method. All conditions of lithography simulations and OPC modeling between two models were same except the mask topography parameters in generating virtual test patterns. Differences in model accuracy and convergence values of regression parameters of each models indicated that current OPC modeling tool based on the thin mask approximated optical simulation did not sufficiently cover the mask topography effect, and 3D mask effect should be considered more carefully.