Diffusion barrier property of molybdenum nitride films for copper metallization

Diffusion barrier characteristics of sputtered molybdenum nitride films in copper metallizations for silicon were investigated in terms of interlayer reactions under various conditions of annealing treatments. The Cu/gamma-Mo2N/Si structure remained stable upon annealing at 600 degrees C for 30 min, but failure of the diffusion barrier occurred after the heat treatment of 650 degrees C-30 min, when molybdenum silicides and copper silicides were thought to be formed. On heating, the stress of the Cu/gamma-Mo2N/Si films decreased due to the agglomeration of the films. Furthermore, interlayer interactions between copper and silicon increased with increasing annealing temperature. These results were investigated by Rutherford backscattering spectrometry, Auger electron spectroscopy, Nomarski microscopy and electrical measurements.