High-Performance Carbon Nanotube Complementary Logic with End-Bonded Contacts

Abstract

Carbon nanotube (CNT) has been envisioned as a promising channel replacement for silicon in sub-5 nm logic technology nodes. Successful implementation of CNT-based CMOS technology requires high-quality low-resistance contacts for both ${p}$ - and ${n}$ -type field-effect transistors (PFETs and NFETs) that can be scaled down to sub-10 nm size. End-bonded contact schemes potentially provide the solution for ultrascaled contacts to CNTs with their low and size-independent contact resistances. In this paper, we report a new form of end-bonded metal contacts made by carbon dissolution into metal contacts with high carbon solubility (e.g., Ni and Co). This new approach requires low annealing temperature (400 °C-600 °C) and maintains metal integrity post contact formation, which has been the major issue in previous metal carbide-based demonstrations where typically >900 °C annealing is required. The end-bonded Ni contacts serve as robust ${p}$ -type contacts to CNTs, and perform better than standard side-bonded Pd contacts at scaled dimensions. In addition, for the first time, we demonstrate CMOS logic with end-bonded Ni contacts, featuring the smallest reported contact size thus far for CNT inverters. These findings could pave the way to realizing CNT-based scalable CMOS technology.