Synthesis of contamination-free silver nanoparticle suspensions for micro-interconnects

Silver nanoparticle suspensions synthesized by chemical reduction from silver nitrate in a formaldehyde reductant and PVP stabilizer using organic bases as the reaction promoter were studied in this research. Two different organic bases of different basicity, triethylamine and pyridine, were used in the reaction. The sizes of the silver particles prepared from the more basic triethylamine were around 20–30 nm. The particles made from the less basic pyridine had smaller sizes (10–20 nm). The suspensions of silver nanoparticles prepared by both methods are free from any metal ion contamination, and are suitable for use in semiconductor industry. The suspensions will be used to make micro-interconnects in integrated circuits (IC) devices by ink-jet printing.