Competitive Adsorption of Small Molecule Inhibitors and Trimethylaluminum Precursors on the Cu(111) Surface during Area-Selective Atomic Layer Deposition: A GCMC Study

In area-selective atomic layer deposition (AS-ALD), small molecule inhibitors (SMIs) play a critical role in directing surface selectivity, preventing unwanted deposition on non-growth surfaces, and enabling precise thin-film formation essential for semiconductor and advanced manufacturing processes. This study utilizes grand canonical Monte Carlo (GCMC) simulations to investigate the competitive adsorption characteristics of three SMIs─aniline, 3-hexyne, and propanethiol (PT)─alongside trimethylaluminum (TMA) precursors on a Cu(111) surface. Single-component adsorption analyses reveal that aniline attains the highest coverage among the SMIs, attributed to its strong interaction with the Cu surface; however, this coverage decreases by approximately 42% in the presence of TMA, underscoring its susceptibility to competitive adsorption effects. By contrast, 3-hexyne displays minimal alteration in adsorption when it is in competition with TMA, effectively inhibiting TMA adsorption and indicating its suitability as a robust SMI for AS-ALD. PT also demonstrates moderate inhibitory capability against TMA, although it is less effective than 3-hexyne in this regard. These findings highlight the importance of intermolecular forces and adsorption energies in determining SMI effectiveness in blocking TMA on non-growth surfaces. Mechanistic insights from this study reveal the nuanced influence of specific SMI-precursor interactions, emphasizing the necessity of selecting SMIs tailored to precursor characteristics and surface interactions. This work provides essential contributions to the rational design of SMIs in AS-ALD, with implications for improving deposition precision and optimizing AS-ALD parameters in nanomanufacturing applications.