Resistance modeling of short-range connections: impact of current spreading

Abstract

We investigated the impact of current spreading on the resistance of short-range connections by performing simulations in Synopsys Sentaurus, based on a calibrated resistivity model. As a main case study, we considered vertical-horizontal-vertical (VHV) connections, a novel cell-routing architecture based on a two-level middle-of-line scheme, that has been proposed to boost the routing of four-track standard cells beyond the 2 nm technology node. We analyzed the impact of vias and line geometry on VHV link resistance and we found that low aspect ratio (AR) lines are needed to minimize the average cell resistance. We performed extensive resistance simulations of various short-range connection schemes beyond VHV links. We concluded that large AR lines are detrimental in all cases in which the link resistance is dominated by the vias. Finally, we show that ignoring current spreading can lead to a significant miscalculation of the link resistance in such scenarios.