Reducing Electrical Resistivity of Copper-CNT Composite Film for High-Ampacity Back End of Line and Interconnection

Abstract

In recent years, sintered silver and sintered copper have attracted attention as die-bonding materials for next-generation power semiconductors. It has been reported that carbon nanotube (CNT)-Cu composites exhibit superior thermal and mechanical properties compared to pure Cu, making them a potential die-bonding material capable of withstanding higher electrical loads. However, a key challenge for CNT-Cu composites is their higher electrical resistivity than that of pure Cu. This study aimed to reduce the electrical resistivity of CNT-Cu nanoparticle (CuNP) composite sintered films to the same level as CuNP sintered films. To achieve this, we experimentally investigated the effects of the composite paste solvent, CNT content, and sintering temperature. Within the scope of this experiment, our results revealed that using ethylene glycol (EG) as the paste solvent, a CNT content of 0.2 wt%, and a sintering temperature of 553 or 573 K were effective conditions for significantly reducing the electrical resistivity of the CNT-CuNP composite films.