ABSTRACT
Carbon nanotubes (CNT) are of interest for interconnects due to their excellent electrical reliability, good electrical conduction and high thermal conductivity. Besides being able to withstand a large current density, CNTs are in general good electrical conductors. For a sufficiently low electrical resistance, a high density of high-quality tubes is required, while for successful integration there are strict demands on the allowed processing temperatures and materials. There are two methods to create CNT vias: either by the traditional top-down approach or bottom-up. In the case of top-down, a contact opening is etched in the dielectric layer between the interconnect levels and subsequently filled with CNTs followed by optional filling of the holes and chemical mechanical polishing (CMP) and finally the deposition of the next metal layer. With the bottom-up method, CNTs are first grown in vertical bundles, followed by dielectric deposition, CMP to make the CNT resurface, and finally metallization.
