Hideaki Hirabayashi

Double-Level Cu Inlaid Interconnects with Simultaneously Filled Via Plugs

A double-level Cu interconnection process for lower submicron generation ULSIs was developed. Cu interconnects were successfully formed by Cu/WSiN sputtering, XeCl excimer laser annealing and Cu/WSiN chemical mechanical polishing. The composition of the WSiN barrier metal was optimized to WSi0.6N and the diffusion barrier capability was confirmed by physical analyses and electrical measurements. The electrical resistivity of the inlaid Cu was 1.9±0.1 µ Ωcm and contact resistivity between the first-level Cu and the second-level Cu was (1.54–5.78)×10-9 Ωcm2. The electromigration lifetime of laser-annealed Cu/WSiN wiring was found to be one order of magnitude longer than that of previously reported Cu interconnects. The activation energy for electromigration was determined to be 1.1 eV.