Reliability and Performance Enhancement for Fully Subtractive Ru Topvia Interconnects

Due to continued scaling of BEOL Cu interconnect dimensions, several challenges have arisen in recent technology nodes such as an increase in line resistance and EM performance degradation. Therefore, post-Cu alternative conductors have been studied extensively as an approach to enable lower line resistance and excellent reliability for sub-20 nm pitch technologies due to their smaller scattering effect, less stringent barrier/liner requirement, and higher melting point compared to Cu [1]-[4]. Moreover, airgap implementation is thought to be essential for the BEOL capacitance reduction of alternative metal interconnects in advanced nodes [5], [6].