Engineering copper surface microstructures for dramatically reduced thermal contact resistance with carbon nanotubes:...

The efficient dissipation of heat from integrated circuits is critically limited by high interfacial thermal resistance (ITR) at material junctions. Vertically aligned carbon nanotube (VACNT) arrays offer a promising solution but they face challenges in integration and exhibit inherently high ITR with metal heat spreaders like copper (Cu). This study employs molecular dynamics simulations to systematically investigate the mechanism regulating the Cu-CNT ITR. By designing and analyzing 24 distinct interfacial structures, it is found that ITR can be either significantly reduced or unexpectedly increased, governed by the interplay between the geometric contact, vibrational density of states (VDOS) overlap, and phonon participation ratio (PPR). Key findings reveal that negative-height nanopillars achieve up to a 75% reduction in ITR dominated by enhanced sidewall contact. Positive-height pillars generally reduce ITR via enhanced VDOS overlap in the 0-7 THz range, but an anomalous increase occurs at low heights due to PPR collapse and strong localization. Similarly, low-density atomic wells reduce ITR by 27.6-42.8%, whereas high-density deep atomic wells increase ITR drastically due to phonon channel collapse in the 3-5 THz range. This work provides fundamental insights and a novel strategy for designing ultra-low-resistance thermal interfaces, facilitating the adoption of VACNT-based thermal management solutions for high-heat-flux applications.