Thermal failure of carbon nanostructures

The greatest weakness of integrated circuits is thermal. Localized temperature increase can significantly degrade circuit performances, sometimes irreversibly. To tackle this issue, carbon-based materials are envisioned as potential candidates to replace metals like copper, tungsten and aluminium. However, little is known about their failure mechanisms. In this thesis, we studied the thermal degradation mechanisms of graphitic materials (Carbon nanotubes, graphite and graphene). To do so, we first examined the joule-heating induced electrical failure of graphene based devices (electro-burning). From our observations, we identified a thermally heterogeneous electro-burning process driven by localised Joule-heating leading to the propagation of a nanometre-spaced gap. To gain more insight into this degradation, we used a femtosecond laser to induce thermal damage to the graphene locally. Our interpretation reveals that heating a graphitic layer leads to the formation of vacancies resulting in an unstable carbon lattice. Finally, we showed how electro-burning, when controlled, can be an advantage. We use a tightly focused femtosecond laser beam to induce defects in graphene according to selected patterns. We show that the nanogaps in pre-patterned devices propagate along the defect line created by the femtosecond laser with a 92\% success rate. Finally, we performed electrical and thermal simulations of an alternative 3D architecture: carbon nanotubes through-substrate vias covalently bonded to graphene/graphite horizontal interconnects. The structure is highly conductive both thermally and electrically and can sustain higher current densities than currently used copper interconnects. However, our results also indicate that graphite anisotropy could worsen the reliability of the architecture due to higher current crowding.Doctor of Philosoph