Comprehensive modeling of electromigration induced interconnect degradation mechanisms

The reliability requirements on modern interconnect and the physical complexity of electromigration phenomena demand close and systematic application of experimental and TCAD based methods for the assessment of interconnect failure and the development of sophisticated layout design rules. We present and discuss state-of-the art electromigration models for both phases of failure development: void nucleation and void evolution. The discussion includes the role of copper microstructure, mechanical stress, capping layer, and void nucleation conditions. A concept for usage of the presented models for prediction of time-to-failure in three- dimensional interconnect geometries is given and demonstrated on examples. The results of simulations are discussed and verified with results of accelerated interconnect testing.