Carbon nanotubes as microbumps for 3D integration

In the future, electronics will face many challenges beyond the prediction of Moore’s law. In this context, nanopackaging will play a crucial role for enabling future electronics to be consistent with future component, system, and circuit board (or global-level) requirements. Moreover, assembly approaches are moving toward heterogeneous three-dimensional integrated circuits (3D ICs) with silicon via wafer thinning, bonding technologies, and 3D system integration and miniaturization. Many of these packaging and assembly requirements are triggering an unprecedented pace of innovation in terms of new technologies, new system integration techniques, and new materials. Intensive research investigations are focused on carbon nanotubes (CNTs), graphene, 2D materials, nanowires, nanoparticles, and so on. In addition, many challenges remain to be faced with regard to the development of state-of-the-art interconnect interfaces, the development of predictive modeling tools based on multidisciplinary and advanced multiscales approaches, and the fabrication and tests of representative demonstrators with a significant impact. The work described in this chapter is in this context. We propose innovative CNTs based on high-frequency interconnections as microbumps. A demonstration of a successfully CNT-based flip chip bonded structure is performed at high frequencies up to 40 GHz. Very encouraging measurements and the dedicated hybrid (EM/analytical) model are in good agreement. We propose that CNT-based microbumps should be a new alternative interconnect for future submillimeter electronics.