Influence of post-bonding heating process on the long-term reliability of Cu/Al contact

Abstract

Copper (Cu) wire bonding had been increasingly used in the LST devices in the last decade, especially in the consumer product due to the cost advantage over gold (Au) wire. Recently, needs for replacing Au wire with Cu wire is increasing also automotive industry where electronic devices need to survive harsher environment for a much longer period of time as compared with consumer product. Accordingly, a research effort for understanding product failure mechanism and reliability testing for the Cu wire bond is more important than ever. In this study, post-bonding heating process was induced after Cu wire bonding as a new approach to understand its effect on bond reliability and further understanding of Cu bond failure mechanism. The results show that introducing the post-bonding heating process is effective to restrain the progress of corrosion at the CuAl IMC during the bHAST (Biased highly accelerated temperature and humidity stress test) and mechanical factors may be related to the progress of corrosion.