"Three-Color" Chemical Selectivity between Oxide, Nitride, and Silicon: Area-Selective Deposition of Metal Oxide and...

Area-selective deposition (ASD) is an appealing bottom-up nanopatterning technique for semiconducting devices, but its capabilities are typically limited to growth and nongrowth surfaces with significantly different chemical properties. Moreover, few studies explore ASD on "multicolor" substrates containing more than two materials. Unlocking the full potential of ASD requires new methods compatible with chemically similar surfaces, such as SiO₂ and SiN. It is shown that exposing nanoscale patterns of SiO₂ and SiN to MoF₆ at 200 °C passivates SiO₂ but allows chemical vapor deposition of polypyrrole and atomic layer deposition of TiO₂ on adjacent SiN. Moreover, using three-color substrates with exposed Si-H, SiO₂, and SiN, transmission electron microscopy shows that one dose of MoF₆ is sufficient to achieve > 9 nm of TiO₂ ASD with S ≳ 0.926 on treated Si-H and SiN versus SiO₂. A mechanism for MoF₆-induced passivation is proposed, involving F transfer and removal of surface -OH groups. It is hypothesized that amine groups remaining on the SiN after MoF₆ subsequently hydrolyze, allowing selective growth on the fluorinated SiN with limited deposition on fluorinated SiO₂. These findings provide new insight for advanced ASD and other atomic scale processes.