Cu Resistivity Scaling Limits for 20nm Copper Damascene Lines

Two of the most important questions concerning the future of interconnects are 1) how scalable is the damascene process to extremely narrow trenches and 2) what is the resistivity of Cu in these trenches? We attempt to answer both these questions through the generation of high aspect ratio, rectangular cross section trenches as narrow as 20 nm using a novel sacrificial Si FIN process flow. To fill such aggressive geometries, we also explore advanced PVD and ALD barrier and seed processes. We find significant electrical yields for 25 to 35 nm test structures with resistivities as predicted by sidewall scattering models.