Expression of Concern: On the Optimal Design, Performance, and Reliability of Future Carbon Nanotube-Based Interconnect Solutions

In this paper, we develop comprehensive modeling and design techniques for carbon nanotube (CNT)-based interconnects, which we utilize to examine the performance, reliability, and fabrication requirements for future nanotube-based interconnect solutions. We create a generalized model for CNT-based interconnect systems that achieves a high degree of accuracy compared to experimental CNT measurements. Leveraging the model, we develop the first closed-form formulation for the optimal nanotube diameter and bundle height for multi-walled CNT (MWCNT) and single-walled CNT (SWCNT) bundle interconnects for a general set of geometric and process parameters. The results indicate that the proposed design method decreases delay by 21% and 29% on average compared to nonoptimized MWCNT and SWCNT bundles. We also find that future CNT bundle fabrication processes must achieve a nanotube area coverage of at least 30% for optimized CNT bundles and 40% for nonoptimized CNT bundles to obtain competitive performance results compared to copper interconnects. In terms of reliability, we find that large diameter MWCNT bundles are significantly more susceptible to process variations than SWCNT bundles, which will have important implications for their utilization in future nanoscale integrated circuits.