A sputter-prepared Ru (7 nm)/WNx (8 nm) stacked layer was investigated as a diffusion barrier layer between Cu and Si for direct-plateable Cu interconnects, and its performance was compared with that of a Ru single layer with the same thickness (15 nm). X-ray diffractometry and sheet resistance measurements showed that the incorporation of WNx into the Ru single layer system significantly improved the barrier performance against Cu diffusion. The Ru/ WNx bilayer barrier stack failed due to Cu diffusion attack after annealing at 750°C for 30 min, while the Ru single layer failed after annealing at 450°C by the formation of Cu silicide (″ -Cu3 Si). A high resolution transmission electron microscopy analysis clearly suggested that this was due to the excellent diffusion barrier performance of WNx film with a nanocrystalline structure embedded in an amorphous matrix.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Materials Science(all)
- Physical and Theoretical Chemistry
- Electrical and Electronic Engineering