Density functional study of initial HfCl4 adsorption and decomposition reactions on silicon surfaces with SiON interfacial layer

The initial adsorption and decomposition of HfCl₄ on silicon surfaces with different types of SiON interfacial layers are investigated using density functional theory. We find that the reactions of HfCl₄ on both the hydroxylated and nitrided silicon surfaces proceed through similar reaction pathways. By comparison of the reaction energies of HfCl₄ with the hydroxyl and amino surface sites, we find that it is both kinetically and thermodynamically favorable for the reactions of HfCl₄ on hydroxyl site of silicon substrates. Comparing with the adjacent bridging oxygen, we also find that the neighboring hydroxyl can facilitate the adsorption of HfCl₄ on the amido surface site. Also, it is more kinetically and thermodynamically favorable for the reaction of HfCl₄ with bridging NH site than that with NH₂ site.