In this study, we are pursuing an ultra low-loss interconnect pathway for 3D chip-chip connectivity, incorporating air-clad planar interconnects, air-clad TSVs, and gradual vertical-horizontal transitions. The motivation is to create an air-gap technology that offers the lowest possible effective k-value and near zero loss tangent minimizing the dielectric loss. The design and modeling of air-gap interconnection is presented. The fabrication challenges in air-clad interconnect lines are discussed. A monolithic inverted air-gap horizontal transmission line structure is proposed as a means for further decreasing the dielectric loss. Extension of air-clad TSV technology for optical transmission is briefly discussed.