Atomic layer deposition of high-κ dielectrics on nitrided silicon surfaces

An atomistic mechanism for the initiation of atomic layer deposition (ALD) of hafnium oxide (HfO2) on nitrided silicon surfaces was investigated using density functional theory. Reactions involving two different metal precursors are studied. Hf[N(CH3)2]4 does not form an adsorbed molecular complex, while HfCl4 has an adsorption energy of 0.30eV. The ALD ligand exchange reaction is direct and 0.19eV exothermic for Hf[N(CH3)2]4 with a barrier of 0.63eV, while it is mediated by a complex intermediate and 0.40eV endothermic for HfCl4 with a barrier of 0.97eV. These results indicate that Hf[N(CH3)2]4 is both thermodynamically and kinetically superior to HfCl4 for the initial ALD of HfO2 on nitrided silicon surfaces.