Reduction of Metal/Carbon Nano-Tubes Interface Contact Resistance by Floating Catalyst Growing Method and Semimetals

In this work, we investigate the contact resistance between carbon nanotubes (CNTs) and different metal electrodes (In, Cr, Cu, Ni, W, and Bi) grown by two methods: floating catalyst chemical vapor deposition (FCCVD) and thin Fe metal chemical vapor deposition (CVD). The results demonstrate that CNTs grown by FCCVD have lower contact resistance with metal electrodes compared to those grown by thin Fe metal CVD. The study attributes this to the avoidance of metal-silicide formation between the silicon (Si) substrate and the metal catalyst film during the high-temperature growing process in FCCVD. Moreover, the research shows that the FCCVD method results in a higher CNT density grown in the through Si vias (TSVs) and lower contact resistance between metal electrodes and CNTs, moving toward the 3-D integrated circuits (3-DICs). Further, the use of metals with good wettability such as bismuth (Bi) as the metal electrode reduces contact resistance.