Study of electromigration at interconnect vias

Results of a study of electromigration at interconnect vias with respect to lifetime of the vias are presented. It is shown that the dependence of the lifetime of the vias on current and on temperature as well as the effect of copper doping is similar to that found in the aluminum stripe. The lifetime is nearly inversely proportional to the number of vias in a chain and the failure occurs in random vias. It is also found that lifetime is affected both by the number of vias and by the total metal length. The lifetime depends on the size of the vias