Bottom-up nanoscale patterning and selective deposition on silicon nanowires

We demonstrate a bottom-up process for programming the deposition of coaxial thin films aligned to the underlying dopant profile of semiconductor nanowires. Our process synergistically combines three distinct methods-vapor-liquid-solid nanowire growth, selective coaxial lithography via etching of surfaces (SCALES), and area-selective atomic layer deposition (AS-ALD)-into a cohesive whole. Here, we study ZrO₂on Si nanowires as a model system. Si nanowires are first grown with an axially modulated n-Si/i-Si dopant profile. SCALES then yields coaxial poly(methyl methacrylate) (PMMA) masks on the n-Si regions. Subsequent AS-ALD of ZrO₂occurs on the exposed i-Si regions and not on those masked by PMMA. We show the spatial relationship between nanowire dopant profile, PMMA masks, and ZrO₂films, confirming the programmability of the process. The nanoscale resolution of our process coupled with the plethora of available AS-ALD chemistries promises a range of future opportunities to generate structurally complex nanoscale materials and electronic devices using entirely bottom-up methods.