Laser direct writing of conductive micropatterns using copper nanoparticle ink toward 3D interconnection

The formation of conductive micropatterns via laser direct writing using metal nanoparticle ink was studied toward 3D interconnection. Copper (Cu) micropatterns were fabricated by laser irradiation on a precursor film prepared via spin-coating of a Cu nanoparticle ink on a substrate. A focused laser beam was scanned on the copper nanoparticle film using a xyz motion control stage. The solution etching of the film after laser scanning gave a Cu micropattern via removing unirradiated area. A copper wiring with a hollow structure was fabricated by layer-by-layer 3D printing, where the spin-coating of Cu nanoparticle ink and the laser direct writing were repeated alternatively.