A Soft Solution Route of Nano-Alumina Direct Patterning onto the Silicon Substrate in Ambient Condition

Functional oxides of nanostructure always require high-temperature reactions, as well as multi-step batch process technology for their fabrication. However, the proposed novel and unique, soft solution process has proven a state-of-art technology in one-step fabrication of various types, shapes, and sizes of oxides nanostructure[1]. Herewith, alumina nanostructures were micro-patterned directly onto the silicon substrate by this route in a very short period and at ambient conditions. In this process, electrochemically polished ultra-sharp tungsten (W) tips of various tip profiles have been used as a local activation by in-situ plasma emission. A very small amount of (~5 ml) polymerized aluminum-citrate matrix was taken as an electrolyte. The patterning of alumina onto the silicon substrate, hence fabricated by the submerged discharge plasma activation technology. The fabricated patterns were analyzed by scanning electron microscopy, Raman, and X-ray photoelectron spectroscopy.<br/>From these analytical studies, we found that the above technique requires a low amount of process materials, single-step fabrication, operation at ambient conditions, and green process[2]. However, the great challenges are in controlling the submerged discharge plasma condition to achieve high-quality patterning in comparison to the highly sophisticated vacuum technology’s fabrication systems.<br/><br/>This study was funded by the National Cheng Kung University 90 and Beyond (NCKU’90) project of grant no. D110-G2309, and in part by Amada Foundation under contract AF-2020227-B3, Tokyo Ohka Foundation for promotion of science and technology, with the collaborative research project of the Institute of Fluid Science, Tohoku University.<br/>Reference:<br/>[1] M. Yoshimura, J. Ceram. Soc. Japan. 114 (2006) 888–895.<br/>[2] S.K. Sahoo et al. ACS Omega. 8 (2023) 17053–17063.