Currently, CNT is considered as one of the primary candidates to outperform Cu concerning performance and reliability as future back-end-of-line (BEOL) interconnect material due to its properties such as ballistic transport, high thermal conductivity, ampacity and strong sp2 bonding between carbon atoms.
Good contacts between CNT and metal electrodes are very challenging. Poor contacts generate significant contact resistance, which severely degrades the performance of CNT as interconnects. Basically, there are two kinds of contacts such as side-contact and end-contact. The side-contact relies on Van der Waals bond while the end-contact has covalent metal-carbon bonds as an interface. In this manual, we use and describe the end-contact. The selected metal electrode is Pd. It should be noted that SWCNT is a particular case of MWCNT and so in the following introduction and discussion, MWCNT is regarded as a representative of CNT interconnect.
On CVD grown CNTs, defects are omnipresent and may impact its performance. The most typical types include vacancies, interstitials, non-hexagonal rings and grain boundaries . Defects can trap or scatter carriers and thus, ultimately impact CNT interconnect performance. Furthermore, CNT diameter, chirality, and defect variations are found to play an essential role in determining the CNT performance as interconnects. So, a MWCNT/SWCNT compact model capable of evaluating the impact of the defects, diameter and chirality variations on its performance is of high interest.
In this project, we present SWCNT and MWCNT interconnect compact models. These models consider the impact of CNT defects, the chirality and contact resistance between CNT-electrode (Pd) on CNT interconnect performances and power consumption. Variabilities of diameter, defect resistance and chirality are also considered in these models by enabling Monte Carlo simulation. Furthermore, the increase in charge based doping of CNT with PtCl4 is evaluated by Fermi level shift which changes the conducting channel of CNT and then impact the performance, power consumption and variability of CNT interconnect.