of Cu/low-k Metallization Systems By

Cu and low-dielectric-constant (k) metallization schemes are critical for improved performance of integrated circuits. However, low elastic moduli, a characteristic of the low-k materials, lead to significant reliability degradation in Cu-interconnects. A thorough understanding of the effects of mechanical properties on electromigration-induced failures is required for accurate reliability assessments. During electromigration inside Cu-interconnects, a change in atomic concentration correlates with a change in stress through the effective bulk modulus of the materials system, B, which decreases as the moduli of low-k materials used as inter-level dielectrics (ILDs) decrease. This property is at the core of discussions on electromigration-induced failures by all mechanisms. B is computed using finite element modeling analyses, using experimentally determined mechanical properties of the individual constituents. Characterization techniques include nanoindentation, cantilever deflection, and pressurized membrane deflection for elastic properties measurements, and chevron-notched double-cantilever pull structures for adhesion measurements