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

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 lowresistance 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 endbonded 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.