High aspect ratio nanostructuring requires high precision pattern transfer with highly directional etching. In this work, we demonstrate the fabrication of structures with ultra-high aspect ratios (up to 10 000 : 1) in the nanoscale regime (down to 10 nm) by platinum assisted chemical etching of silicon in the gas phase. The etching gas is created by a vapour of water diluted hydrofluoric acid and a continuous air flow, which works both as an oxidizer and as a gas carrier for reactive species. The high reactivity of platinum as a catalyst and the formation of platinum silicide to improve the stability of the catalyst pattern allow a controlled etching. The method has been successfully applied to produce straight nanowires with section size in the range of 10-100 nm and length of hundreds of micrometres, and X-ray optical elements with feature sizes down to 10 nm and etching depth in the range of tens of micrometres. This work opens the possibility of a low cost etching method for stiction-sensitive nanostructures and a large range of applications where silicon high aspect ratio nanostructures and high precision of pattern transfer are required.
CITATION STYLE
Romano, L., Kagias, M., Vila-Comamala, J., Jefimovs, K., Tseng, L. T., Guzenko, V. A., & Stampanoni, M. (2020). Metal assisted chemical etching of silicon in the gas phase: A nanofabrication platform for X-ray optics. Nanoscale Horizons, 5(5), 869–879. https://doi.org/10.1039/c9nh00709a
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