Electromigration resistance of TiWN/Cu/TiWN interconnections

Abstract The present paper describes the activation energy for electromigration damage (EMD) of the Cu multilayer interconnection. The Cu multilayer (TiWN/Cu/TiWN) interconnections (width ∼ 0.7 μm) were fabricated by the Ar-sputtering method. The electromigration (EM) resistance measurements were carried out on a wafer level. The AlCu multilayer (TiN/AlCu/TiN/Ti) interconnections were also prepared by the conventional process, and EM resistance was evaluated by the same method. A current density applied to the interconnection was in the range of 16 to 24 MA/cm 2 . After the EM test, voids were formed in the Cu layer of the TiWN/Cu/TiWN multilayer, and the Cu hillocks were formed at the anode side. The activation energies for electromigration damage (EMD) of the Cu and AlCu interconnections were 0.97 and 0.62 eV, respectively. The activation energies and medium time to failures (MTF) of Cu and AlCu showed that the lifetime of the Cu interconnections at 110°C was about three orders of magnitude longer than that of AlCu.