Simulation study on the robustness of polar mark for incident light polarization states

In order to improve the alignment accuracy of advanced lithography processes, the polar mark was designed to balance the requirement between pitch size device matching and process uniformity. In this paper, the polar mark is studied using the rigorous coupled wave method, as the period is close to the incident wavelength. The robustness of polar mark for incident light polarization states is investigated. Comparing with segmented alignment mark, the polar mark showed better robustness. And polar mark exhibits high process adaptability. The determination of the polar mark pattern density must be in combination with the process. The wet recess process changes the wafer quality (WQ) of the polar mark. The polar mark with this process still has good polarization robustness. The research content of this paper shows significance in enhancing the alignment performance of lithography.