CoW alloy as multi-function diffusion barrier material for next-generation Cu metallization

In this study, CoW alloy co-sputtered with various conditions was investigated as a Cu diffusion barrier to replace the conventional Cu seed/liner/barrier structure. By fabricating Cu/CoW/Si stacks, we found that under certain Co/W ratio, CoW layers showed similar wetting ability with Ta and can avoid Cu diffusion up to 570 °C for 56 min. Furthermore, Cu was found capable to be directly electroplated on CoW layers. As a result, a single layer of CoW alloy which demonstrates electroplating, wetting and barrier ability simultaneously could become a promising material for next-generation Cu metallization.