Proximal probe-like nano structuring in metal-assisted etching of silicon
Yamani, Zain Hassan
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CitationBahceci, E., Enders, B., Yamani, Z., Tokmoldin, S., Taukenov, A., Abuhassan, L., Nayfeh, M. (2019). Proximal Probe-like Nano Structuring in Metal-assisted Etching of Silicon. AIP Advances. 9(5), 055228. https://doi.org/10.1063/1.5096659
We use silicon having multiple crystalline orientation domains and high metal doping in metal assisted chemical etching (MACEtch) in HF/H2O2. In device-quality silicon, MACEtch produces high-aspect ratio anisotropic (1-D) structures (wires, columns, pores or holes) and to a lesser degree non-high-aspect ratio luminescent (0-D) nano structures. While the 1-D structure symmetry is understood in terms of crystallography axis-dependent etching, predominantly along the <100> direction, the isotropic 0-D spherical symmetry etching is not understood. We observe in silicon having multiple crystalline orientation domains formation of metal tips (needles or whiskers) of diameters as small as 2-3 nm that bridge the metal to silicon and cause AFM/STM-like nanofabrication, producing 0-D mounds, indentations, or clusters. The formation of sharp needles can be understood in terms of charge injection/electric breakdown between metal clusters and silicon due to charge build-up. Silicon with high degree of impurities as well as with multiple crystalline orientation domains allow imaging these effects using electron spectroscopy without cross sectional cuts.