New complementary PVD-Ta/CVD-WN stacked barrier structure for copper metallization

A PVD-Ta/CVD-WN stacked barrier structure has been newly developed. Its PVD-Ta layer and CVD-WN layer work complementarily. Its conformal CVD-WN layer provides an excellent barrier performance and helps the overlying Cu seed suitable for Cu filling. Its PVD-Ta surface layer which contacts Cu directly provides an agglomeration-resistive interface and suppresses migration-up of Cu in features in thermal processes. Its PVD-Ta layer also solves the galvanic corrosion which had been an issue in CMP of the directly contacting Cu/WN system. Sharp distribution in line resistance has been successfully obtained for Cu interconnects with the newly developed complementary PVD-Ta/CVD-WN barrier.