Effect of NH3-plasma treatment and CMP modification on TDDB improvement inCu metallization

Time-dependent dielectric breakdown (TDDB) between Cu interconnects is inve stigated. TDDB lifetime strongly depends on the surface condition of the Cu interconnect and surrounding pTEOS, A NH3-plasma treatment prior to cap-pS iN deposition on Cu interconnect improved the dielectric breakdown lifetime (tau (BD)) over cap-pSiN deposition only, The plasma treatment also has th e beneficial effect of suppressing wiring resistance increase during pSiN d eposition. These results suggest that CuO reduction to Cu, and CuN formatio n at the Cu interconnect surface prevents Cu silicidation during pSiN depos ition Furthermore, SiN formation and bond termination by hydrogen radicals at the pTEOS surface diminish surface defects such as dangling bonds. TDDB lifetime also strongly depends on the Cu CMP process, in which mechanical d amage of the SiO2 surface during CMP process degrades TDDB, Adoption of a m echanical damage free slurry or a post-CMP HF treatment to remove the damag ed layer from the surface improves TDDB,