Low-temperature area-selective MLD of polyurea on OTS-SiO2 nanopatterned substrates fabricated via microcontact printing

초록

Area-selective deposition (ASD) provides a bottom-up approach to nanostructure fabrication by exploiting the differences in chemical reactivity between surfaces. Although area-selective atomic layer deposition (AS-ALD) has been extensively studied to enable conformal-and thickness-controlled inorganic film growth, the development of area-selective molecular layer deposition (AS-MLD) remains in its early stages. AS-MLD of organic thin films is particularly relevant for applications in sensors, energy storage, and optoelectronics; however, the understanding of process-structure-selectivity relationships remains limited. In this study, we demonstrated AS-MLD of polyurea using 1,4-phenylene diisocyanate (PDIC) and ethylenediamine (ED) precursors on octadecyltrichlorosilane self-assembled monolayer (OTS SAM)-SiO2 nanopatterned substrates. After the MLD window was established on hydrophilic and hydrophobic blanket substrates, microcontact printing was employed to generate OTS SAM-SiO2 nanopatterns. The effects of the precursor pressure, pulse duration, and pattern scale on film selectivity were investigated using atomic force microscopy and scanning electron microscopy. The results highlight the importance of molecular transport and steric effects at the nanoscale for achieving high selectivity and provide valuable insights into the parameter space required for reliable AS-MLD of polymer thin films.

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