Deterministic fabrication of sharp amorphous silicon oxide nanocones using a single mask

Silicon nanocone formation is well-documented, yet current methods for fabricating silicon oxide nanocones often involve intricate processes, non-deterministic placement, or suffer from poor uniformity. We present a single-mask dry etching technique for the fabrication of amorphous silicon oxide nanocones featuring sharp tips, smooth sidewalls, and deterministic distribution onto substrates. This procedure leverages plasma-enhanced chemical vapor deposition of silicon oxide, followed by electron beam lithography for patterning. Our dry etching process utilizes a thin alumina hard mask with selectivity exceeding 88, enabling the creation of high aspect ratio nanocones with tip sizes limited only by electron beam lithography resolution. We further introduce a novel multistep dry etching approach to achieve ultra-sharp amorphous silicon oxide nanocones with tip diameters as small as 10 nm. The presented processes open up exciting possibilities, including the fabrication of amorphous nanocone arrays onto unconventional substrates or their use as nanoscale probes. We demonstrate the seamless integration of amorphous silicon oxide nanocones into existing nanofabrication process flows by incorporating them onto silicon-on-insulator-based micro-electromechanical springs.