Interconnects exhibiting enhanced electromigration short-length effects by line width variation

A novel model and approach for obtaining improved electromigration short-length effects are reported. The results for a structure with Dual Damascene copper-based metallization and two width regions demonstrate that increasing the line width for a portion of the line length generates longer electromigration lifetimes. Moreover, the lifetimes are accurately characterized by introducing an equivalent length for the structure that depends on the width and length of each region. The results are explained in terms of a modulation of the stress profile in the structure with more than one width region. A consequence of these findings is increased design flexibility since more options are available to improve the electromigration reliability of short interconnects.