High aspect ratio arrays of Si nano-pillars using displacement Talbot lithography and gas-MacEtch

Structuring Si in arrays of vertical high aspect ratio pillars, ranging from nanoscale to macroscale feature dimensions, is essential for producing functional interfaces many applications. Arrays silicon 3D nanostructures are needed realize photonic and phononic crystals, waveguides, metalenses, X-ray wavefront sensors, detectors. In particular, nanopillars used as bio-interfaces neural activity recording, cell culture, microfluidics, sensing on-chip manipulation. Here, we demonstrate a strategy realizing protruding sharp nanopillars, using displacement Talbot lithography combined with metal-assisted chemical etching (MacEtch) gas phase. Such combination enables reliable low cost pathway fabrication ordered on large scale. With the double exposure linear grating mask orthogonal orientations lift-off technique, realized catalyst pattern holes Pt thin film period 1 μm hole diameter range 100–250 nm. MacEtch phase by vapor HF oxygen air allows etch 200 nm-thick (pillar height/width) an rate up μm/min. Gas-MacEtch has advantage no capillary stiction, ion beam damage substrate, nanometric resolution fidelity transfer. controlled uniformity size area, spatial frequency doubling lithography, proposed method easy-to-scale-up processing that can support pillars valuable applications both at micro nano-scale.