Thickness effect on the diffusion barrier properties of ZrN in Cu/ZrN/Si systems

Stoichiometric ZrN films were grown on Si (100) substrates using reactive dc magnetron sputtering and the resistivity and the lattice parameter of these films were studied by post-annealing up to 900°C. Upon annealing, not only increased grain size results but also is the higher mobility by relieving internal stress and by decreasing disorder in the lattice. Therefore, the effect of the annealing on the ZrN films is to decrease their resistivity. Subsequently, the diffusion behavior of the constituent species in the Cu/ZrN/ Si stacks was examined by annealing. The diffusion coefficient and activation energy of Cu in the ZrN barrier were determined with various ZrN thickness. The enhanced barrier properties for the thicker ZrN film was explained in terms of its microstructure.