Electrical properties of carbon nanotube via interconnects for 30nm linewidth and beyond

The continuous downward scaling in integrated circuit (IC) technologies has led to rapid shrinking of transistor and interconnect feature sizes. While scaling benefits transistors by increasing the switching speed and reducing the power consumption, it has an adverse impact on interconnects by degrading its electrical performance and reliability. Scaling causes reduction in interconnect linewidth, which leads to surge in resistance due to increased contributions from grain boundary and surface scattering of electrons in the metal lines. Further, current density inside interconnects is also enhanced by the reduced linewidth and is approaching or exceeding the current-carrying capacity of the existing interconnect metals, copper (Cu) and tungsten (W). The resulting failure due to electromigration presents a critical challenge for end-of-roadmap IC technology nodes. Therefore, alternative materials such as nanocarbons and silicides are being investigated as potential replacements for Cu and W as they have superior electrical and mechanical properties in the nanoscale. In this review, the electrical properties of nanocarbons, in particular carbon nanotubes (CNTs), are examined and their performance and reliability in the sub-100nm regime are assessed. Further, the measured properties are used to project 30nm CNT via properties, which are compared with those of Cu and W.