Measurement point selection for in-operation wear-out monitoring

In recent IC designs, the risk of early failure due to electromigration wear-out has increased due to reduced feature dimensions. To give a warning of impending failure, wear-out monitoring approaches have included delay measurement circuitry on-chip. Due to the high cost of delay measurement circuitry this paper presents a method to reduce the number of necessary measurement points. The proposed method is based on identification of wear-out sensitive interconnects and selects a small number of measurement points that can be used to observe the state of all the wear-out sensitive interconnects. The method is demonstrated on ISCAS85 benchmark ICs with encouraging results.