PNNL

Abstract

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.