Abstract
NbN x films were prepared by RF reactive magnetron sputtering from a Nb target in N2/ Ar gas mixtures and then used as diffusion barriers between Cu and Si substrates. Material characteristics of the NbN x, films were investigated and were correlated with the N2/Ar flow ratio. The variations in film resistivity is correlated with the change of phases and chemical compositions from α-Nb, β-Nb 2 N, γ-Nb 4 N 3 , δ-NbN + δ′-NbN as the N2/Ar ratio is increased. The thermal stability of Cu (60 nm)/NbN x (25 nm)/Si multilayers were investigated and our results indicated that the barrier performances were significantly affected by the chemical composition of NbN x films. The diffusion coefficient of Cu in NbN x was measured by four-point probe analysis after annealing Cu/NbN x /Si multilayered samples in the temperature range of 600-850° C. Cu diffusion in NbN x had components from the grain boundaries and the lattice. In addition, our results suggest that the NbN x can be used as a potential diffusion barrier for Cu metallization as compared to the conventional TaN. © 2013 The Electrochemical Society.