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 similar to 1.8 eV and, through FA, we associate it to grain boundary diffusion. Conservative lifetime predictions confirm a high J(MAX) but high self-heating (>100 degrees C) @J(MAX). We venture that Ru J(MAX) will be limited by the maximum heating allowed at each interconnect level without degrading the chip performance.