Study of the Bottom Antireflective Coating Process Using a High-Transparency Resist for ArF Excimer Laser Lithography

Abstract

We have investigated the effect of substrate reflectivity and resist transparency on resist performance in ArF excimer laser lithography with bottom antireflective coating (BARC). Both depth-of-focus (DOF) and exposure latitude in low-transparency (49% per 0.5 µm thickness) resist were improved as the substrate reflectivity was decreased. However, the DOF and the exposure latitude decreased, since the resist profile was tapered on the extremely low-reflectivity (∼0%) substrate. On the other hand, the DOF of high-transparency (67% per 0.5 µm thickness) resist was wider than that of low-transparency resist and was independent of substrate reflectivity. The exposure latitude also improved with decreasing reflectivity. High-transparency resist achieved a 0.75 µm DOF at 0.15 µm lines and spaces (L/S) on BARC using a 0.60-NA lens without any resolution enhancement techniques. Good critical dimensional control at 0.15-µm L/S patterns over the topography with 200-nm step was obtained without significant linewidth variation. Gate etching was successfully achieved down to 0.11 µm L/S with the etching conditions developed for KrF resists.