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

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.