Stability of Nitrogen and Hydrogen in High-k Dielectrics

ABSTRACTWe report here on atomic transport, thermal stability, and chemical evolution of HfSiO, HfSiN, and AlON films on Si(001), aiming at investigating the atomic scale behaviour of the involved chemical species, N and H in particular, when the films are submitted to usual thermal processing steps in inert and oxidizing atmospheres. The films were characterized by nuclear reaction analyses in resonant and non-resonant regions of the cross-section curves, X-ray photoelectron spectroscopy, and low energy ion scattering. The HfSiN/Si structure was shown to be more resistant to oxygen diffusion than HfSiO/Si, although the amounts of O incorporated in HfSiN/Si are larger than in HfSiO/Si. The main channel of oxygen incorporation is atomic exchange with nitrogen or oxygen atoms. HfSiN film on Si incorporate more hydrogen (or deuterium) and in more stable configurations than HfSiO/Si. Nitrogen incorporation into AlON films on Si renders this structure more stable against thermal annealing in vacuum and/or oxidizing atmospheres than Al2O3/Si.