Effects of copper and titanium addition to aluminum interconnects on electro- and stress-migration open circuit failures

Electromigration (EM) lifetimes are determined for pure Al, Al-0.1-wt.% Cu, Al-0.15-wt.% Ti, and Al-0.1-wt.% Cu-0.15-wt.% Ti as a function of the line width. The addition of 0.15-wt.% Ti improves the EM resistance, in which the lifetime increases with decreasing linewidth. The lifetimes of Al-0.1-wt.% Cu are similar to pure Al. The stress migration (SM) open failures are also evaluated. The Ti addition has a deteriorating effect on SM. The Cu addition, however, substantially improves the SM resistance. The simultaneous addition of Cu and Ti improves both EM and SM resistances