Halogen Induced Corrosions in Gold Aluminium (Au-Al) Wire bonds

Abstract

Wire bonding is a widely used interconnection technology in semiconductor packaging, ensuring electrical and mechanical reliability in microelectronic devices. Among various wire bond materials, gold-aluminum (Au-Al) bonding remains a preferred choice due to its stability, malleability, and oxidation resistance. However, prolonged operation and environmental exposure lead to intermetallic compound (IMC) formation, Kirkendall voiding, and eventual bond degradation, compromising long-term device reliability. While extensive research has been conduct-ed on wire bond failure mechanisms, the role of different halogens—particularly their influence on IMC degradation, voiding, and failure progression—remains insufficiently explored. Additionally, the outgassing of halogens from commonly used engineering plastics in semiconductor-tor packaging presents a potential but poorly understood risk, raising concerns about accelerated degradation.

This study systematically investigates halogen-induced corrosion in Au-Al wire bonds by evaluating IMC growth, void formation, and failure mechanisms under controlled high-temperature storage life (HTSL) conditions. Additionally, the study examines how pre-grown IMCs influence degradation when exposed to halogens. A series of HTSL tests were performed on post-production semiconductor components, followed by mechanical testing, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) for microstructural and compositional analysis.

Key findings indicate that halogen exposure significantly accelerates Au-Al bond degradation, with increased IMC growth, Kirkendall void formation, and severe corrosion effects observed at higher halogen concentrations. The degradation rate and failure speed varied among different halogen types, highlighting their distinct influences on wire bond reliability. Additionally, pre-grown IMCs exhibited differential resistance to corrosion, suggesting that aging prior to halogen exposure delays failure mechanisms. Furthermore, humidity was identified as a critical factor in accelerating halogen-induced corrosion, emphasizing the need for environmental control in reliability assessments.

These findings contribute to improving reliability assessment methodologies for semiconductor devices and MEMS (Microelectromechanical Systems) packaging. This research enhances the understanding of halogen-induced degradation in Au-Al wire bonds and informs future material selection strategies to enhance long-term device stability.