Molecular phonon couplers at carbon nanotube/substrate interface to enhance interfacial thermal transport

A novel assembling process of incorporating carbon nanotubes as thermal interface materials for heat dissipation has been developed by synthesizing vertically aligned carbon nanotubes on a copper substrate and chemically bonding the carbon nanotubes to a silicon surface. The assembling process and the copper/carbon nanotubes/silicon structure are compatible with current flip-chip technique. The carbon nanotubes are covalently bonded to the silicon surface via a thin but effective bridging layer as a “molecular phonon coupler” at the CNT–silicon interface to mitigate phonon scattering. Experimental results indicate that such an interface modification improves the effective thermal diffusivity of the carbon nanotube-mediated thermal interface by an order of magnitude and conductivity by almost two orders of magnitude. The interfacial adhesion is dramatically enhanced as well, which is significant for reliability improvement of the thermal interface materials.