First-principles calculations reveal precursor-dependent reaction mechanisms in ZrO2 atomic layer deposition

While atomic layer deposition (ALD) of ZrO2 enables conformal, high–κ dielectric films with sub-nanometer thickness control, the atomistic origins of precursor-dependent reactivity remain unresolved. Here, density functional theory (DFT) is used to dissect the ligand-controlled half-reactions of ZrO2 ALD using TDMAZr and TEMAZr with O3 as the oxidant. During the first half-cycle, TDMAZr adsorption and dissociation proceed with a lower maximum activation barrier and a more exothermic profile than TEMAZr, establishing TDMAZr as the kinetically more reactive precursor. In contrast, O3 oxidation of TEMAZr-derived surfaces proceeds with both a lower activation barrier and greater exothermicity, indicating faster kinetics, deeper thermodynamic stabilization, and more complete ligand removal for the EMA pathway. Electronic structure analysis (PDOS and Bader charge transfer) reveals broader O 2p–N 2p hybridization and larger charge redistribution for tri-EMAZr, consistent with its stronger electronic activation toward O3 oxidation, whereas tri-DMAZr reaches a deeper adsorption energy minimum, supporting more stable precursor anchoring during the first half-cycle. Collectively, these results reveal a kinetic–thermodynamic complementarity in which TDMAZr accelerates precursor activation, whereas TEMAZr enables both faster and more complete oxidation, rationalizing the observed trade-off between growth rate and film quality and guiding rational precursor selection for amido-based ZrO2 ALD.