Fabrication of Cu nanowires along atomic step edge lines on Si(111) substrates

We have succeeded in the fabrication of high-aspect-ratio (length to width) Cu nanowires along atomic step edge lines on Si(1 1 1) substrates. The fabrication procedure consisted of two wet process steps: (1) flattening of the surface roughness to an atomic level by immersing Si(1 1 1) wafers in ultralow-dissolved-oxygen water (LOW), and (2) Cu nanowire formation by immersion in LOW containing 10 ppm Cu ions for 1 s at room temperature. On the other hand, no Cu nanowires were formed on the Si(1 1 1) surfaces when the dissolved oxygen content was 8 ppm in alkaline solution during the Cu deposition stage, even though the Si etching with OH− was enhanced. We consider that it is due to the decrease in reduced Cu atom density by the existence of the dissolved oxygen as superoxide anion radicals.