Combined experimental and DFT analysis of initial adsorption behavior in HfZrO₂ thin films on TiN surface

Zirconium-rich composition in HfZrO₂ thin films deposited by atomic layer deposition (ALD) using cocktail precursors is frequently observed, despite equimolar precursor delivery. This study identifies the origin of this deviation through experimental analysis and density functional theory (DFT) calculations. While CpZr and CpHf exhibit similar reactivity with ozone, supercycle ALD experiments and DFT results reveal stronger adsorption of CpZr on TiN substrates due to lower physisorption, bond dissociation, and chemisorption energies. These findings demonstrate that preferential surface adsorption, not gas-phase reactivity, governs initial composition, emphasizing the importance of substrate–precursor interactions in composition control.