Microstructure and thermal stability of CuSiN self-aligned layer in advanced copper interconnect multilayer films

A CuSiN self-aligned layer with 4 nm in thickness was synthesized by a step-reaction between plasma and Cu film surface in RF-plasma-enhanced chemical vapor deposition system. The microstructure of Si/SiO₂/TaN/Ta/Cu (CuSiN)/SiC:H/SiOC:H multi-layer stacks was investigated by using HRTEM, EDS and XRD. The results indicate that SiN and Cu (Si) layers appeared in bothsides of CuSiN layer, and the thermal stability of the interface of Cu/SiC:H dielectric barriers can be improved by introducing CuSiN self-aligned layer which suppressed copper atom or vacancy diffusion into SiC:H/SiOC:H dielectric film along the interface.