Epitaxial Ruthenium for Advanced Interconnects

As interconnect scaling approaches sub-10 nm critical dimensions, conventional Cu interconnects face increasing challenges, including resistance scaling, degraded electromigration, and complex integration requirements. Recently, Ru has emerged as a promising alternative for barrier-and linerless interconnects due to its more favorable resistance scaling and superior intrinsic electromigration resistance. Epitaxial single-crystal Ru presents additional advantages over polycrystalline Ru, since the absence of grain boundaries reduces resistivity and enhances etching behavior. In this paper, we demonstrate the epitaxial growth of Ru (001) on Si (111) wafers using an AlN (001) buffer layer, an approach that is scalable to 300 mm wafer processing. Furthermore, we explore the feasibility of Ru epitaxy with alternative crystallographic orientations on sapphire substrates. Finally, we discuss potential integration pathways for epitaxial Ru films in advanced interconnects.