Stability Analysis of Nanoscale Copper-Carbon Hybrid Interconnects

Abstract

Copper Carbon (Cu-Carbon) hybrid interconnect is a new and an extremely promising candidate for future VLSI circuit applications, so it needs to be analyzed for not only propagation delay but its stability should also be examined in order to consolidate its claim as an alternative to existing interconnect configurations. In this work, stability analysis of the recently proposed Cu-Carbon hybrid interconnect is performed and compared with existing alternate hybrid interconnect candidates (i.e. copper, copper-graphene hybrid and copper-carbon nanotube composite). A three-line coupled interconnect system for 7 nm technology node is considered in this study whose dimensional parameters are adopted as per the IRDS roadmap guidelines. The unit-step response of Cu-Carbon hybrid interconnect is steepest as compared to others because of its lowest switching delay. Cu-Carbon hybrid appears to be the most stable as its nyquist plot intersects farthest from the critical point (-1, j0) towards origin. The effect of crosstalk leads to undershoots as seen in the time domain response of copper interconnects, but it does not have any notable effect on Cu-Carbon hybrid interconnects. It is evident that as the fraction of carbon nanotube in Cu-Carbon hybrid (Fcnt) increases, bandwidth increases due to decrease in resistance. Also, Cu-Carbon with Fcnt = 0.8 is most stable amongst all configurations. We conclude that Cu-Carbon hybrid is the most stable candidate among all the alternative interconnect configurations, claiming it to be a desirable interconnect alternative for near-future VLSI applications.