Aluminum electromigration of 1-mil bond wire in octal inverter integrated circuits

Aluminum electromigration of 1-mil GND bond wires in Octal Buffer Inverter integrated circuits packaged in ceramic DIPs was observed after a few years usage in the field. Bench simulations on functionally good parts that were returned from the field were performed to replicate failures and to determine under what conditions the part would fail in a similar fashion. The simulations were also conducted to determine if the failures were caused by aluminum electromigration, electrical-overstress (EOS) or electrostatic discharge (ESD). The burned-out bonding wires of the field failures were characterized by broken or melted wires with some amount of recrystallization. The field failures did not show any evidence of burned-out areas on the die or in the metallization runners. The morphology and the microstructures of the burned-out bond wires exhibited evidence of the aluminum electromigration. The thinning and the thickening of parts of the wires indicate that there was an aluminum mass redistribution associated with the electromigration process. The "bamboo" structure of the wire that resulted from the electromigration is clearly obvious and revealing. The aluminum electromigration process of these 1-mil bond wires as well as the solutions to the problem will be discussed.