Recently, advancing RF interconnect technologies for future 2.5D and 3D integration have been identified as an important game changer for energy efficient complex integrated circuit systems. Researchers are improving the performance of traditional interconnect technologies, such as wire bonds, and are exploring novel technologies as alternative interconnect solutions, such as stich chip and copper nanowire vias. Due to the high speed needs of 5G and 6G communication, interconnect operation needs to extend into the millimeter and sub-millimeter wave frequency range, which poses big challenges for designs with low loss and broad bandwidth. Herein, this review discusses and describes recent advances in interconnect technologies for wired and wireless RF applications. The research work is promising and shows a variety of methods to achieve low loss over a broad range of frequencies needed to truly enable design of energy efficient complex integrated circuit systems.