Fabrication of a Nanometer-Scale Si-Wire by Micromachining of a Silicon-on-Insulator Substrate

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Abstract
Air-bridge-structured Si wires were fabricated by using a silicon-on-insulator (SOI) substrate and electrically characterized. The SOI substrate used had a sandwich structure of a 200-nm-thick p-type Si layer (SOI layer), a 400-nm-thick buried oxide layer (BOX layer) and a p-type Si substrate. The wires were made by conventional photolithography process followed by dry etching and thermal oxidation thinning of the SOI layer. The Si wires were isolated from the substrate by an air gap made in the BOX layer and had dimensions of typically 20 nm in width, 40 nm in height and 150 nm in length. It was found from the measurements of current-voltage characteristics that the current through the wires much increased by illumination with a He-Ne laser and reached about 20 nA at a bias of 1 V.