Novel Corrosion Prevention Treatments for Cu Wire Bonded Device to Improve Bonding Reliability

In this paper, we report an efficient corrosion screening method using micro-pattern test structures for analyzing Al bond pad corrosion in Cu wire bonded assembly. The new insights of the corrosion mechanism on Al bond pad in chloride environment help to identify, for the first time, the hydrogen evolution is the key cathodic reaction for the observed acute Al bond pad corrosion. We developed a novel prevention treatment based on this new corrosion mechanistic understanding. The subsequent failure analyses of treated Cu wire bonded device assembly showed excellent resistance to the chloride-induced Al bond pad corrosion. The molded Cu wire bonded devices treated with selected corrosion inhibitor passed the electrical failure tests even under massive internal chloride contamination and harsh autoclave stress test for 48 hours.