Fabrication of 70-nm-Pitch Two-Level Interconnects by using Extreme Ultraviolet Lithography

Abstract

A 70 nm pitch two-level interconnects have been successfully fabricated using extreme ultraviolet lithography (EUVL) (λ=13.5 nm). EUVL enabled us to obtain fine pattern formation and usable overlay accuracy at each metal and via patterning. CF3I etching gas and ruthenium (Ru) barrier film deposited with physical vapor deposition (PVD) are key technologies for achieving good electrical properties. Very low effective resistivity of less than 4.5 µΩ cm in 35-nm-width wiring was obtained by using PVD-Ru barrier film. Via resistance of 12.4 Ω for via-holes with diameter of 35 nm was obtained.