Metal reliability mechanisms in Ruthenium interconnects

Abstract

We perform a detailed assessment of different reliability mechanisms in Ru interconnects. We show that full Ru vias have no risk of voiding after long thermal storage (>1200 h) at high temperature. Our estimate of the electromigration activation energy is ~1.8 eV and, through FA, we associate it to grain boundary diffusion. Conservative lifetime predictions confirm a high JMAX but high self-heating (>100 °C) @JMAX. We venture that Ru JMAX will be limited by the maximum heating allowed at each interconnect level without degrading the chip performance.