Aggravated Electromigration of Power Distribution Networks in ULSI Devices Due to Local Resonant Oscillations

In this paper, the impact of resonant voltage oscillations, triggered on on-die power supply and ground grids by switching of active elements, upon electromigration (EM) and Joule heating of the interconnects, constituting the grids, has been studied. The recorded voltage waveforms inside a working microchip reveal that the voltage oscillations on these grids can locally attain amplitude that is even higher than 10% with regard to the supply voltage. It was observed that these oscillations can appear with an opposite phase at two adjacent power grid areas, thus giving rise to strong currents. These experimentally measured waveforms have been taken as a basis for our calculations. The results reveal that resonant voltage oscillations on both power supply and ground grids lead to a substantial aggravation of both EM and Joule heating. Furthermore, it was found that the situation is aggravated with the growth of the voltage oscillations´ frequency.