Lateral Ordering of Microfabricated SiO2 Nanotips

Micro -fabricated SiO₂ nano - tips are potentially useful as scanning tips in near field optical microscopy and sensor related functions. We report a process in which the rounding nature of isotropic etching is effectively used to micro -fabricate laterally ordered SiO₂ nano -tips. Combination of excessive isotropic wet etching of thermally grown SiO₂ with anisotropic etching of n type silicon along planes leads to the formation of nano -tips with sharpness ~ 15 nm. Uniform periodic array of nano -tips form due to coalescence of excessively etched SiO₂ resulting in nano -tips length the separation between the original photolithographic features. Finally, the overall process of nano -tip formation is discussed by considering the roles of rapid isotropic etching of SiO₂ in buffered oxide etch solution, anisotropic etching of Si in KOH solution, and slow SiO₂ etching in KOH solution.