Fabrication of vertically stacked single-crystalline Si nanowires using self-limiting oxidation

A simple method for fabricating vertically stacked single-crystal silicon nanowires on standard bulk silicon wafers is presented. The process uses inductively coupled plasma (ICP) etching to create silicon fins with uneven yet controllable vertical profiles. The fins are then thermally oxidized in a self-limiting process, and the narrow regions are completely consumed to create multiple nanowires vertically stacked on each other. It was found that the number of nanowires in the vertical stack depends on the number of ICP cycles. A mechanism for the formation of the nanowires is proposed and confirmed with numerical simulations.