Hierarchical current-density verification in arbitrarily shaped metallization patterns of analog circuits

Electromigration is caused by high current-density stress in the metallization patterns and is a major source of breakdown in electronic devices. It is, therefore, an important reliability issue to verify current densities within all stressed metallization patterns. In this paper, we propose an efficient methodology for hierarchical verification of current densities in arbitrarily shaped custom-circuit layouts as commonly used in analog circuits and analog blocks in mixed-signal ICs. Our approach includes a quasi-three-dimensional model to verify irregularities, such as vias and incorporates thermal simulation data to account for the temperature dependency of the electrical field configuration and the electromigration process. The described methodology, which can be integrated into any IC design flow as a design rule check, has been successfully tested and verified in commercial design flows.