This chapter introduces the interconnects in semiconductor devices. It explains the damascene process for fabricating copper (Cu) interconnects. The chapter briefly addresses reliability concerns and explores how manganese (Mn) doping can enhance Cu interconnect performance. It then outlines criteria for identifying materials “better than Cu”. Cobalt (Co) was proposed to replace Cu or its liner layers. Ruthenium (Ru), which have been explored in dual-, single-, and semi-damascene processes. Beyond elemental metals, intermetallic compounds–particularly NiAl–are presented as promising candidates for future interconnects. Finally, back-side power delivery networks (BSPDNs), which is an architectural innovation that reroute power lines from the wafer’s backside to increase the interconnect density on the front side. The cover image of this chapter is showing the 3D copper interconnect in microprocessors firstly produced by IBM in 1997. Reprint Courtesy of IBM Corporation © 2025.