In situ observation of electromigration-induced void migration in dual-damascene $Cu$ interconnect structures Available to Purchase

In situ electromigration experiments were carried out to study electromigration-induced failure in the upper and lower layers in dual-damascene $Cu$ test structures. The observations revealed electromigration-induced void movement along the $Cu$/dielectric cap interface. It supports the premise that $Cu∕Si3N4$ interface acts as the dominant electromigration path. However, the observed void nucleation occurs in the $Cu∕Si3N4$ interface at locations which are far from the cathode, and void movement along the $Cu∕Si3N4$ interface in opposite direction of electron flow eventually causes void agglomeration at the via in the cathode end. The different electromigration behaviors of the upper and lower layer dual-damascene structures are discussed.