Microstructure and resistivity of nanoscale Co-Pt intermetallic compounds for scaled interconnects

Abstract

As the complexity of integrated circuits increases, current copper (Cu) based interconnect metallization can no longer withstand the parasitic resistance-capacitance (RC) signal delay. Therefore, it is vital to develop nanoscale materials for scaled interconnects that have all three characteristics: low electrical resistivity, thermal stability, and a high potential for barrierless integration. This study explores cobalt (Co)‑platinum (Pt)-based nanowires (NWs) with a focus on their intermetallic compounds (IMCs), including Co1Pt3, Co1Pt1, and Co3Pt1. These IMCs appear attractive due to their chemical stability under thermal budget constraints. We employ the three-electrode electrodeposition and post-deposition annealing to fabricate nanoscale Co-Pt IMCs. We characterize the electrical properties of a single NW using a four-point probe in a vacuum. The measured resistivity values of the Pt-less Co3Pt1 NWs with diameters of 30 and 130 nm are 77.85 and 35.04 μΩ cm, respectively. Moreover, to emulate the dielectric environment in the back-end-of-line (BEOL) process, silica (SiO2) coating is applied to the NWs. We observe no appreciable interdiffusion of Co and Pt into silica after heat treatment at 450 °C for 6 h.