A Cu–Cu Wire-Bonding Enabled by a Cu-Selective Passivation Coating to Enhance Packaging Reliability
John Alptekin, Kevin Antony Jesu Durai, Dinesh Kumar Kumaravel, Logan Estridge, Oliver Chyan, Rusli Ibrahim, Guangming Li, Varughese Mathew
Abstract
Semiconductor device packaging reliability specifications are tightening toward a low ppb to zero defect rate standard due to the increasingly stringent automotive safety requirements. When exposed to chloride ions contamination, the typical copper (Cu) to aluminum (Al) wire-bonding connection could be a potential source of corrosion-related reliability concerns in wire-bonded devices. This article studies the effect of replacing the Al bond pad with Cu on the corrosion-induced lift-off of wire bonds when exposed to low ppm levels of chloride contamination. Real-time immersion corrosion screening was carried out on a wire-bonded device for accelerated time-dependent observation of corrosion progression in 100-ppm chloride solution. The newly developed Cu–Cu wire-bonded devices, enabled by selective passivation to prevent Cu oxidation, dramatically outperformed Cu–Al wire-bonded devices in complete immersion in chloride solution. A chemically discerning reflection–absorption infrared spectroscopy (RAIRS) metrology was used to measure the oxidation suppression provided by a mere few nanometers of passivation coating.