ACCNT: A Metallic-CNT-Tolerant Design Methodology for Carbon Nanotube VLSI: Analyses and Design Guidelines

We present analyses for ACCNT (pronounced as “accent”), which is a solution to the metallic-nanotube problem that does not require any metallic-nanotube removal of any kind. ACCNT uses asymmetrically correlated carbon nanotubes to achieve metallic-nanotube tolerance, delivering high ON-OFF ratios while preserving current drive. We analyze the ACCNT methodology in terms of its tradeoffs and explore optimizations that may serve as future design guidelines. We also investigate circuit-level considerations and the impact of density variation on the ACCNT design. We find that ACCNT can improve the yield of a one-million transistor chip from 0% (conventional CNT design) up to 99% at a cost of 3.3× area overhead if the fraction of semiconducting CNTs is improved to 99.9%.