Fabrication of Vertical Silicon Nanotube Array Using Spacer Patterning Technique and Metal-Assisted Chemical Etching

We propose a process combining metal-assisted chemical etching and a spacer patterning technique to fabricate dense, vertical silicon nanotubes (SiNTs) with sub-60 nm wall thickness, which may have potential advantages for various devices. Moreover, we investigate the effect of the etch rate controlled by the mixture solution ratio to obtain SiNTs with ideal morphology. The fabricated high aspect ratio SiNTs exhibit good structural stability, leading to bundle-free arrays, which can be ideal for nanostructure-based suppression of optical reflection.