Deuterium Isotopic Effect on Nanometer-Sized Narrow Spaces Formed by Silicon Walls

Unveiling a solid–liquid reaction in a nanoconfined region is required to control the wet processes of advanced semiconductors whose sizes can reach several nanometers. In this study, using deuterium isotope effects, we investigated the influence of reactant consumption by confining walls on the etching rate of nanoconfined spaces. By analyzing the states of the silicon surface and the etching rate of SiO 2 film confined by the silicon walls in hydrofluoric acid diluted with H 2 O or D 2 O, we observed that deuterium can suppress the reaction on the wall surface and that deuterium fluoride increases the etching rate in nanoconfined regions. Therefore, we conclude that the wet-etching behavior can be determined by the reactant consumption on the confining walls.