The Impact of Ball-Bonding Induced Voltage Transient on Sub-90nm CMOS Technology

In this paper, the impact of ball bonding (BB) induced voltage transient on the reliability test including electro-migration (EM), time dependent dielectric breakdown (TDDB), negative bias temperature instability (NBTI) and electro-static discharge (ESD) are investigated. During the electronic flame-off (EFO) of ball bonding process, a spark discharge current, which applies a high electric field between the wire and wand, is used to melt the wire to form a free air ball (FAB). In the mean time, however, the spark may generate ions in the air and some of them may charge to die for package. After free air ball was bonded to pad, a BB-induced voltage transient can be measured and may impose an electrical stress to devices, then to degrade the device lifetime if without suitable I/O protection circuits. The degradation mechanism can be considered as charge device model (CDM) electrostatic-discharge (ESD) event. To remove or reduce this package-induced damage, ionizers had been put closely to the bonding tool and showed very good package yield, compared to those without ionizer.