Process window analysis of the ARC and TAR systems for quarter-micron optical lithography

摘要

A practical process window, considering the standing wave effect, was investigated for anti-reflective coating (ARC) and top anti- reflector (TAR) in KrF excimer laser lithograph, using an accurate profile simulator. The practical process window was defined on the exposure/defocus plane as the area where two process windows at the resist thicknesses corresponding to maximum and minimum linewidths on a swing curve are overlapped. ARC and TAR thickness latitude values for optimized ARC and TAR refractive indexes are also discussed. Simulation results show that the practical process window for the TAR system is wider than that for the ARC system, since the sidewall angle decreases by the use of ARC. Although TAR thickness latitude is smaller than that for ARC, the TAR system has an advantage in regard to reliable device fabrication, considering both the practical process window and the thickness latitude.