1 July 2005 Polarization effects in immersion lithography
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Optical proximity correction (OPC) tools are already equipped with the most advanced models for image formation and are capable of thin-film modeling, vector diffraction modeling, and polarization modeling. Accurate simulation of immersion lithography, even in the context of OPC, does not pose any particular difficulty. We use the optical simulator of a commercial OPC software to study source polarization and its impact in process latitude and in proximity and linearity curves. More than a 10-nm difference in both curves is observed versus source polarization at an immersion numerical aperture (NA)>1, projected to print the 45-nm node. Simulation of large and arbitrary layout snippets confirms these results and demonstrates the feasibility of using advanced models in the context of OPC. Also, dry and water-immersion lithography are compared at the same NA<1 and the main differences in imaging are highlighted. The depth-of-focus (DOF) increase in immersion is confirmed in both the ambient medium and the available DOF in resist. The DOF simulation results correlate closely with recent experimental work from other researchers.
Konstantinos Adam, Wilhelm Maurer, "Polarization effects in immersion lithography," Journal of Micro/Nanolithography, MEMS, and MOEMS 4(3), 031106 (1 July 2005). https://doi.org/10.1117/1.2038687

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