Understanding nitrogen-induced effects on the performance of ultra low-k dielectric systems through ab initio simulations

Large scale ab initio molecular dynamics simulations were performed to investigate how Cu/ultra low-k systems are improved when N is incorporated into the pore-sealing layers. It was found that the high affinity of N to Ta and H gives rise to new phases that prevent H atoms from penetrating the Ta diffusion barrier layer. Consequently, the Ta layer forms organized structures with good barrier performance and electrical conductivity. Furthermore, a continuous ductile film is formed to seal the highly porous polymer dielectrics. Interfacial adhesion between the pore-sealing layer and the dielectrics is also enhanced by inter-diffusion.