Buried Power Rail Integration with Si FinFETs for CMOS Scaling beyond the 5 nm Node

Buried power rail (BPR) is a key scaling booster for CMOS extension beyond the 5 nm node. This paper demonstrates, for the first time, the integration of tungsten (W) BPR lines with Si finFETs. The characteristics of CMOS in close proximity to floating BPR are found to be similar to the characteristics of CMOS without BPR. Moreover, W-BPR interface with Ru via contact can withstand more than 320 h of electromigration (EM) stress at 4 MA/cm2 and 330 °C, making Ru a candidate for via metallization to achieve low resistance contact strategy to BPR.