Time-dependent dielectric breakdown (TDDB) between Cu interconnects is investigated. TDDB lifetime strongly depends on the surface condition of the Cu interconnect and surrounding pTEOS. A NH3-plamsa treatment prior to cap-pSiN deposition on Cu interconnect improved the dielectric breakdown lifetime ( G~) over cap-pSiN deposition only. The plasma treatment also has the beneficial effect of suppressing wiring resistance increase during pSiN deposition. These results suggest that CuO reduction to Cu, and CUN formation at the Cu interconnect surface prevents Cu silicidation during pSiN deposition. Futhermore, 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 damage of the Si02 surface during CMP process degrades TDDB. Adoption of a mechanical damage free slurry or a post-CMP HF treatment to remove the damaged layer from the surface improves TDDB .

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Cu metallization technology using sputtered Cu wiring and W-plug is developed. Submicron trenches for wiring with even 0.4 p m in width are filled with Cu by a low-pressure long-throw sputtering method followed by a reflow process. Blanket-W