Characteristics of a 10 nm-thick (TiVCr)N multi-component diffusion barrier layer with high diffusion resistance for Cu interconnects

To fulfill the strict demands for Cu interconnects below 65 nm, a 10 nm-thick (TiVCr)N film with ternary metallic elements was developed in this study as a candidate diffusion barrier by reactive sputtering in an N2/Ar mixed atmosphere. Barrier properties were examined by annealing over a temperature range of 700–900 °C for 30 min. From the analyses of diffusion behaviors after thermal annealing at 700 °C, the electrical resistance of the Si/(TiVCr)N/Cu film stack remained as low as the as-deposited value. No interdiffusion between the Si substrate and the Cu metallization was found through the (TiVCr)N film at temperatures as high as 700 °C. After annealing at 800 °C, the penetration of a partial number of Cu atoms through the (TiVCr)N barrier occurred and thus some Cu silicides were formed. With temperature further increased to 900 °C, severe interdiffusion of Si and Cu through the layer occurred and induced the formation of a large amount of Cu silicides. This demonstrates that TiVCr ternary refractory metal nitrides have potential use as effective diffusion barriers for copper metallization.

Research highlights
► A 10 nm-thick (TiVCr)N film was developed as a candidate diffusion barrier.
► The excellent diffusion resistance of the (TiVCr)N film at 700 °C was verified.
► The full dense microstructure provides a great resistance to the diffusion of atoms.