Chemically Distinct Adsorption of Sulfide Inhibitors for Multi-Surface Passivation and Area Selective Deposition

Area-selective atomic layer deposition (AS-ALD) is a promising approach for precise thin film deposition and nanoscale patterning in 2D and 3D architectures. Since ALD growth is strongly dependent on surface chemistry, area-selective deposition (ASD) can be achieved either through intrinsic differences in surface reactivity or through deliberate surface functionalization via chemisorption of molecules called inhibitors that suppress thin film formation on targeted surfaces or via promoters that favor thin film formation on desired surfaces. Therefore, understanding the selective adsorption of these molecules as well as their interactions with ALD precursors and reactants is crucial for determining growth versus non-growth surfaces and the extent of surface passivation. In this study, two organosulfide inhibitors, dipropyl sulfide (DPS) and isopropyl sulfide (IPS), have been utilized for AS-ALD on Cu, SiO₂, and TiN surfaces. Despite sharing the same chemical composition, DPS and IPS exhibit distinct adsorption behaviors. Both DPS and IPS selectively adsorbed on Cu, whereas only DPS adsorbed on SiO₂, while both inhibitors remained unreactive toward TiN. Density functional theory (DFT) calculations suggest that the inhibitors can dissociate into fragments whose adsorption geometries differ between substrates, enabling DPS to achieve multi-surface passivation while IPS remains surface selective.