Direct nanofabrication of copper on silicon substrate by electrochemical atomic force microscope lithography

The electrochemical reaction by applying an electrical bias between an atomic force microscope (AFM) tip and a substrate was used to directly fabricate desired copper patterns. The negative sample bias could strongly reduce copper at the point localized by an AFM tip but not oxidize silicon. The mixture solution of Cu(NO3)2 and poly(sodium 4-styrenesulfonate) which are highly soluble in water was used to form a conductive copper ion film. The arrayed dots and line patterns were fabricated by electrical exposure at regular steps and continuous bias, respectively. This technique demonstrated the fabrication of copper patterns by using the electrochemical reduction by AFM lithography.