Review of multi-layer graphene nanoribbons for on-chip interconnect applications

A review of the analytical models for signal transport in multi-layer graphene nanoribbon (GNR) interconnects, current distribution between GNR layers, and a comparison of GNR interconnects against copper is presented here. The multiconductor transmission line (MTL) models and the simplified equivalent distributed RC models presented here consider the realistic effect of having contacts that couple only to the top layer. The MTL models are used to show the distribution of current among different layers along the interconnect length. For digital circuits and interconnect dimensions of interest, it is shown that the equivalent RC models have an error of less than 15% in estimating the interconnect delay. However, for RF circuits where the accurate frequency response is important, it is shown that MTL models are essential. The optimal number of GNR layers to minimize the delay and energy-delay-product (EDP) are derived using the distributed RC models for futuristic technology nodes. Using the predictions made by the International Technology Roadmap for Semiconductors (ITRS), it is shown that for short interconnects, multi-layer GNR with smooth edges can outperform copper.