SiO₂ atomic-layer fluorination-passivation for dual-material molybdenum/polypyrrole area-selective deposition and strategies for surface reactivation Available to Purchase

Recent research on area-selective deposition (ASD) has begun to expand beyond ASD of one material on two different surfaces (i.e., a two-color substrate) to explore multicolor substrates and multimaterial ASD processes. This study introduces molybdenum (Mo) metal and polypyrrole (PPy) dual-material ASD by employing the dual-functionality of molybdenum hexafluoride (MoF₆). Mo atomic layer deposition, using MoF₆ and silane (1 wt. % SiH₄ in Ar), selectively deposits Mo on hydrogen-terminated silicon (Si—H) vs hydroxylated SiO₂ (SiO₂—OH), while concurrently forming fluorine-passivated SiO₂ (SiO₂—F). We find that subsequent PPy oxidative chemical vapor deposition, using pyrrole and antimony pentachloride (SbCl₅), is suppressed on SiO₂—F, as confirmed by x-ray photoelectron spectroscopy, cross-sectional scanning electron microscopy, and time-of-flight secondary ion spectrometry analyses. This inhibitory effect enables the formation of self-aligned, colocalized Mo/PPy nanostructures on Si—H vs SiO₂—OH via a sequential integration of two distinct deposition processes: (1) Mo ASD on Si—H vs SiO₂—OH and (2) PPy ASD on Mo vs SiO₂—F. The stability of fluorine-passivation on SiO₂—F in air is further examined. Importantly, we also demonstrate methods to successfully remove the surface passivation (i.e., rehydroxylation of SiO₂—F), suggesting the potential for additional ASD on reactivated SiO₂ using PPy ASD as a sacrificial mask layer.