Fabrication of arbitrarily shaped silicon and silicon oxide nanostructures using tip-based nanofabrication

The authors report fabrication of arbitrary shapes of silicon and silicon oxide nanostructures using tip-based nanofabrication (TBN). A heated atomic force microscope (AFM) tip deposits molten polymer on a substrate to form polymer nanostructures that serve as etch mask to fabricate silicon or silicon oxide nanostructures. The authors demonstrate how TBN can be combined with conventional wet etching as well as metal-assisted chemical etching, in order to fabricate these nanostructures. The size of the TBN-fabricated silicon nanostructures is around 200 nm. Silicon nanostructures fabricated using metal-assisted chemical etch can have very smooth sidewalls with, roughness as small as 2 nm. The authors show fabrication of arbitrary shapes of silicon and silicon oxide nanostructures including those with curved and circular shapes. Our results show that TBN using a heated AFM tip can function as an additive nanolithography technique with minimum contamination, and is compatible with existing nanofabrication methods.