Instability of incorporated nitrogen in HfO2 films grown on strained Si0.7Ge0.3 layers

Abstract

The interfacial characteristics and thermal stability of nitrided HfO2 films grown on strained Si0.7Ge0.3 layers were investigated by medium energy ion scattering, high-resolution x-ray photoelectron spectroscopy, and near-edge x-ray absorption fine structure. N incorporation of HfO2 films grown on Si0.7Ge0.3 layers was strongly related to the diffusion of Si and Ge from strained Si0.7Ge0.3 layers in the interfacial region between HfO2 films and Si0.7Ge0.3 layers by the annealing treatment in NH3 ambient. The chemical states of SiOxNy and GeOxNy were formed in the interfacial region by N incorporation, and SiOxNy was dominant chemical states rather than that of GeOxNy. However, the incorporated N was not stable, which was mostly diffused out during the postnitridation annealing in a N-2 ambient. The instability of incorporated N through the additional annealing treatment extensively caused the change in the structure of HfO2.