Innovative Cu-Selective Passivation Coatings for Enhanced Reliability in Cu Interconnects for IC Packaging

Copper (Cu) is widely considered as the material of choice for most interconnects in IC packaging due to its cost-effectiveness and superior electrical and thermal properties, making it integral to high-performance and energy-efficient electronic devices. However, Cu's susceptibility to corrosion and oxidation significantly challenges its reliability in various applications. This study focuses on utilizing an innovative Cu-selective passivation coating designed to enhance the reliability of Cu-Al wire bonding and promote flux-less Cu-to-solder wafer-level bonding applications. Our results showed the passivation coating effectively inhibits halide-induced corrosion by passivating exposed Cu regions on palladium-coated Cu (PCC) wires, and the ultra-thin(<10nm) passivation coating significantly reduced Cu oxidation and showed successful thermocompression bonding (TCB) without flux in ambient conditions. This critical advancement in addressing the reliability challenges in Cu interconnects offers a cost-effective solution, paving the way for more robust and reliable ICs in microelectronics packaging.