Environment of hafnium and silicon in Hf-based dielectric films: An atomistic study by x-ray absorption spectroscopy and x-ray diffraction

The atomic structure of HfSiO and HfSiON was investigated before and after thermal annealing using x-ray diffraction and x-ray absorption spectroscopy. In HfSiO, the Hf atoms are arranged in a monoclinic HfO₂ structure with Hf as second nearest neighbors, while Si is in a SiO₂ environment. Thermal annealing induces crystallization of HfSiO with subtle changes in Hf–Hf distances. In the case of HfSiON, a stable structure is observed around the Hf atoms, which remains unaffected after annealing. Nitrogen is present in the first coordination shell of the Hf atoms, with Si in a SiON environment.