Inorganic ARC for 0.18 μm and sub-0.18 μm multilevel metal interconnects

The accelerated control of critical dimensions (CD) in the sub-0.25 μm region for semiconductor manufacturing has increased worldwide interest in the antireflective coating (ARC) process. In this paper, we report on a novel inorganic ARC design for deep-UV lithography and implementation of the ARC into multilevel metal interconnects for 0.18 μm and sub-0.18 μm technologies. The designed Si_xO _yN_z ARC not only reduces substrate reflectivity to a minimum and prevents DUV resist footing, but also serves as a hard mask for metal etch. Back-end-of-line (BEOL) sub-0.25 μm multilevel metal patterning and etch with the Si_xO_yN_z ARC produced excellent metal profiles and 100% electrical comb yields. The designed ARC has also shown superior results to the conventional TiN metal ARC. The dielectric constant value is close to that of silicon oxide