Insight Into Electromigration Reliability of Buried Power Rail With Alternative Metal Material

As the technology node scales toward 1 nm, the emerging metal materials are being explored as the potential replacements for Cu interconnects. To better understand the electromigration (EM) of different metals used in actual interconnection layers, in this work, we investigate the EM reliability of buried power rail (BPR) with alternative metal materials, including W, Ru, Co, and Mo. The kinetic Monte Carlo (KMC) simulation is used to describe the microcosmic migration paths of metal atoms and the void morphology under EM stress. The time-to-failure (TTF) of BPR and middle-of-line (MOL) consisting of different metals are comprehensively discussed by considering the conductive mechanism, thermal effects, stress gradients, and current flows. The optimal metallic selection guidance is further provided to improve the EM lifetime of BPR, which helps accelerate the development of advanced integration technology beyond 3 nm.