Recently, ArF immersion lithography has been considered as a promising method after ArF dry lithography by a factor of refractive index n of the liquid filled into the space between the bottom lens and wafer, in the case of 193-nm exposure tools, water (n = 1.44) has been found as the best liquid. We explore the NAσ's dependence of depth of focus (DOF) under 3/4 annular and 3/4 quasar illumination by resist imaging simulation. Line/space pairs of line-to-space ratios 1:1, 1:2, 1:4 on binary mask
