Electromigration in damascene copper interconnects of line width down to 100 nm

The electromigration reliability of Cu interconnects of line width down to 100 nm is investigated. The activation energy for the electromigration failure of the line width of 150 nm is found to be 1.2 eV, and the Cu/Ta interface is found to be the fast diffusion path for the line widths of 100 nm and 150 nm without any catastrophic void formation in the lines. An atomic flux divergence-based finite element model is used to explain the observed failure sites. Both the resistivity and electromigration reliability of the fabricated interconnects are found to be promising for future technology nodes.