Exposure systems having high numerical apertures (NAs) are essential for increasing the resolution of optical lithography. The efficiency of conventional single-layer bottom antireflective coating (BARC) structures, however, degrades as the angle of incidence increases. In this paper we demonstrate a multilayer BARC structure for high-NA systems employed in ArF lithography. Because the reflection difference between transverse electric (TE or s) and transverse magnetic (TM or p) polarization at the air-resist interface results in low image contrast for high-NA exposure systems, we also describe a single-layer top antireflective coating (TARC) layer that can be used to reduce the polarization effect. By combining the optimized TARC and multilayer BARC structures, the swing effect can be alleviated and the image contrast can be improved for angles of incidence ranging from 00 to 700 (i.e., NA = ca. 0.93). (C) 2008 Elsevier B.V. All rights reserved.
