The regulation mechanism of heat transport at Cu/a-C/3C-SiC heterointerface by interlayer thickness and laser shock

Abstract

It is proved that the introduction of an interlayer into typical heterostructures can effectively improve the interfacial thermal conductance (ITC) in semiconductor chips. Thus, structure changes of the amorphous carbon (a-C) interlayer caused by the thickness and laser shock duration and related effect on the ITC at the Cu/a-C/3C-SiC heterointerface are investigated in depth by non-equilibrium molecular dynamics, simulated magnetron sputtering, vacuum annealing and laser shock. As the increase of the thicknesses, the ITCs significantly increase first, and then decrease slowly. Notably, a thickness of 0.5 nm increases the ITC by a factor of 3.49. The enhancement mechanism stems from the fact that the introduction of all a-C layers enhances the phonon density of states (PDOS) at 13–21 THz, activates high-frequency phonons at 35–65 THz, reduces the phonon mismatch between Cu and 3C-SiC. However, a further enlargement in thickness increases the amorphous structure, decreases the number of phonons in the ranges of 0–9 THz and 22–29 THz, weakens the phonon coupling at the a-C/3C-SiC sub-interface, ultimately, the ITCs reduce accordingly. Additionally, with the increase of the laser shock durations on the a-C layer, the ITCs show a gradual decrease, with the maximum decrease of 11.55 %. This phenomenon originates from the situation that laser shock decreases the surface roughness of the a-C and the effective contact area at the interfaces, reduces the interfacial van der Waals interactions, attenuates the phonon matching at the Cu/a-C sub-interface. The above analysis provides important reference value for thermal management of GaN-based power chips.