Blocking mechanisms in area-selective ALD by small molecule inhibitors of different sizes: Steric shielding versus chemical passivation

Pengmei Yu, Marc J.M. Merkx, I. Tezsevin, Paul Lemaire, Dennis M. Hausmann, Tania E. Sandoval (Corresponding author), W.M.M. Kessels, Adriaan J.M. Mackus (Corresponding author)

Onderzoeksoutput: Bijdrage aan tijdschriftTijdschriftartikelAcademicpeer review


Small molecule inhibitors (SMIs) hold great promise for area-selective deposition due to their vapor-phase application being compatible with industrial processing. However, to date only a handful of SMIs have been studied, and the mechanisms of precursor blocking require further understanding. In this study, we explore the inhibition of SiO2 ALD on Al2O3 surfaces comparing three SMIs of different sizes: acetic acid (HAc), acetylacetone (Hacac), and 2,2,6,6-tetramethyl-3,5-heptanedione (Hthd). The goal is to unravel the contributions of two important factors to their blocking performance: steric shielding, i.e. physically covering reactive surface sites, and chemical passivation, i.e. chemically consuming surface reactive sites. Experimentally, it is found that HAc and Hthd outperform the previously studied Hacac, as revealed by longer nucleation delays on functionalized Al2O3 from in-situ spectroscopic ellipsometry, and by enhanced Si precursor blocking inferred from in-situ infrared spectroscopy. Through density functional theory and random sequential adsorption simulations, we illustrate that varying the size of SMIs brings benefits from either higher steric shielding or better chemical passivation. As compared to Hacac, HAc performs better due to its smaller size, yielding denser packing and thus higher chemical passivation. Hthd on the other hand, benefits from its bulkiness with a higher contribution from steric shielding.
Originele taal-2Engels
Aantal pagina's9
TijdschriftApplied Surface Science
StatusGeaccepteerd/In druk - 24 apr. 2024


The authors thank Lam Research Corp. United States for supporting this work. A.J.M.M. and I.T acknowledge support from European Research Council (ERC No. 949202) under the European Union's Horizon 2020 research and innovation program. A.J.M.M. and M.J.M.M thank support from the Dutch Research Council (NWO, the Netherlands) through the Vidi project 18363. T.E.S. acknowledges funding from ANID (Agencia Nacional de Investigaci\u00F3n y Desarrollo, Chile) through FONDECYT 1231197 (Fondo Nacional de Desarrollo Cient\u00EDfico y Tecnol\u00F3gico, Chile). This research was partially supported by the supercomputing infrastructure of the NLHPC, Chile (ECM-02).

Lam Research Corporation
National Agency for Research and Development
Horizon 2020 Framework Programme
European Research Council949202
Nederlandse Organisatie voor Wetenschappelijk Onderzoek18363
Fondo Nacional de Desarrollo Científico y Tecnológico1231197


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