Photo-chemically assisted redox-nano welding for highly conductive and robust copper-based electrodes

In this study, high-quality conductive electrodes were fabricated by improving the sintering efficiency and packing density of Cu sub-microparticle (sub-μP) electrodes through IPL sintering with redox reaction-induced nano-welding. This process includes both pre-oxidation and photothermal chemical reduction. The pre-oxidation in the Cu sub-μP electrodes can easily be triggered (within a few seconds) via a hot air treatment (500 °C). The oxidized Cu sub-μP electrodes are reduced and sintered simultaneously through a photothermal chemical reaction during the IPL sintering process. Cu nanoparticles, which are newly formed in the photothermal chemical reduction process, play an important role as interconnection materials between Cu sub-μPs during the IPL sintering process. The effect of exposure time and temperature in the hot air treatment on the oxidation properties of Cu sub-μPs are investigated systematically using noncontact spectroscopic temperature-sensing techniques and X-ray diffraction analysis. After IPL sintering, the conductive Cu sub-μP electrodes showed highly sintered morphologies, which resulted in extremely low electric resistivity (8.34 μΩ cm) under optimal conditions.