Role of Impurity Segregation into Cu/Cap Interface and Grain Boundary in Resistivity and Electromigration of Cu/Low-fr Interconnects

摘要

The role of impurity segregation into the Cu/cap interface and grain boundary is discussed in terms of resistivity and electromigration (EM) lifetime. A Co-based metal capping, a CuAl seed, and new liners (Ti, Zr, and Hf) are compared as technologies for EM lifetime improvement. The roles of impurity in grain growth and electron scattering are investigated by residual resistivity measurement and physical analysis. The EM lifetime distribution and activation energy of lifetime are also investigated. The efficiency of EM improvements is discussed in terms of the trade-off characteristics of each technologv during use. The EM improvement efficiency is categorized into three groups.