Nano-structured silver coating on copper prepared in an ethanol-based solution

Recently, silver as an electrochemical deposit on copper substrate has been attracting much attention in the microelectronics field. To deposit nano-scale silver particles on copper, immersion plating using cyanide-based baths is commonly used. In this study, non-toxic ethanol was used as the plating solution. Sputtered copper samples were immersed in an ethanol-based solution containing 0.2 g·L−1 silver for silver deposition. The silver deposits were characterized by a field emission scanning electron microscope (FE-SEM), an energy dispersive X-ray spectroscope (EDS), and an atomic force microscope (AFM). It was found that the deposited particles are metallic silver. After 3 s immersion, fine particles whose diameters were around 6 nm had covered about 40% of the surface of the copper substrate. After 10 s immersion, the copper surface was completely covered by silver particles, the diameters of which have increased to about 10-15 nm. After the whole surface was covered, a dense and smooth silver coating was obtained.