Si nanostructures formed by pattern-dependent oxidation

A quantitative evaluation of the local Si thickness of oxidized Si nanostructures was performed by scanning probe microscopy. Suppression of oxidation by mechanical stress is a dominant factor in determining the shape of Si structures of widths <100 nm. Oxidation from below caused by oxygen diffusion in the buried oxide layer extends to a few hundred nanometers from the pattern edge. The vertical position of the Si structure can be changed within a few tens of nanometers by oxidation from below. As a result of co-occurence of these two phenomena, the local thickness of the patterned Si layer can be controlled within a range of 0-300% of the unpattemed area thickness.