Electromigration reliability of Cu interconnects and the impact of low-k dielectrics

Electromigration (EM) reliability in Cu dual-damascene structures integrated with oxide and low-k ILD was investigated using a statistical approach. This approach is efficient in addressing early failures using multi-link structures to sample very large number of interconnect elements. In this paper, we summarize results first on early failures of Cu/oxide structures, then EM characteristics of Cu/low-k structures are discussed and compared with Cu/oxide structures. The integration of low-k ILD was found to degrade EM performance and to induce a new failure mechanism. These results can be attributed to the thermomechanical properties of the low-k ILD and its implication on EM reliability will be discussed.