Mechanism of Precursor Blocking by Acetylacetone Inhibitor Molecules during Area-Selective Atomic Layer Deposition of SiO2

Area-selective atomic layer deposition (ALD) is currently attracting significant interest as a solution to the current challenges in alignment that limit the development of sub-5 nm technology nodes in nanoelectronics. Development of area-selective ALD processes with high selectivity requires understanding of the mechanisms involved in the loss of selectivity. In this work, the use of acetylacetone (Hacac) inhibitor molecules in ABC-type cycles for area-selective ALD of SiO2 is investigated as model system to gain insight into precursor blocking. In situ infrared (IR) spectroscopy measurements show that at saturation, Hacac adsorbs in a mixture of chelate and monodentate bonding configurations. Hacac adsorbates in monodentate configuration were found to desorb as a result of purging or be displaced by bis(diethylamino)silane (BDEAS) precursor dosing and therefore significantly contribute to the loss of selectivity during area-selective ALD. Density functional theory (DFT) calculations reveal that the obse...