Cu Wire resistance improvement using Mn-based Self-Formed Barriers

Cu wire resistance reduction using CVD Mn-based Self-Formed Barrier (SFB) compared to conventional PVD barrier was investigated at 40 and 100 nm half pitch (HP). Mn-based SFB leads to both (1) maximum fractional Cu area in the trenches and (2) Cu resistivity reduction at scaled dimensions. This represents a breakthrough for future interconnect scaling. Blanket Cu experiments suggest that the Cu resistivity reduction in the case of Mn-based SFB can be attributed to lower surface scattering at the dielectric/Cu interface. Finally, promising reliability has been demonstrated in 20 nm HP single damascene (SD) SiO₂ trenches integrated with Mn-based SFB.