Electromigration in a two-level Al-Cu interconnection with W studs

Electromigration lifetime tests on single-level Al-Cu interconnection with straight and meandering lines and two-level Al-Cu interconnection with W stud chains have been carried out. The electromigration resistance of W stud chains was found to be less than half of that of Al-Cu straight lines. The discontinuity of Cu supply at Al-Cu/W interfaces accounts for most of the reduction in the electromigration resistance of W stud chains. The shorter electromigration lifetime in W stud chains and Al-Cu meandering lines as compared to Al-Cu straight lines reflects the effect of current crowding at studs.