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

Abstract

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.