In this work, the utilization of Cu-AI alloy seed for 90nm node Cu dual-damascene interconnects has been investigated for its effect on reliability improvement. Via reliability, such as stress induced voiding and electromigration resistance, was greatly improved without an unacceptable increase in via resistance. A small amount of Al in Cu seems to help prevent the diffusion of vacancies and Cu atoms in Cu interconnects. Using Cu-AI alloy seed is one of the most promising and simple techniques to improve the via reliability of Cu interconnects for the 65nm node and beyond.