An automated methodology to fix electromigration violations on a customized design flow

Electromigration (EM) effects have been a high concern in IC power delivery networks design. As the integrated circuits dimensions become smaller and smaller, those effects become a critical reliability failure mechanism on signal nets and they are known as AC electromigration. The EM problem is not only a reliability matter but it compromises the IC performance, accelerates the aging effects and reduces its lifetime. Most commercial design tools allow to analyze and prevent EM effects. Yet, fixing EM issues demands a considerable charge of handwork. This work follows a previous study done at our group, where a methodology to fix electromigration issues was tested and the corrections where applied manually into a customized design flow. That methodology showed an improvement going from 33% to 83% on the distribution of current density through critical signal interconnections. Now, for the best using of this technique, it is proposed a methodology that automates the electromigration fixing flow, without manual interventions. The basis of the method is to gather the critical nets suffering from high current densities, give them a weight based on their dimensions and the current density and to use integer linear programming (ILP) to calculate the necessary dimension of the nets. So, it can mitigate the electromigration effects for a given mean time to failure (MTTF).