Atomic Layer Deposited RuO₂ Diffusion Barrier for Next Generation Ru‐Interconnects

Abstract

Abstract Atomic layer deposition (ALD) is a suitable technology for conformally depositing thin films on nanometer‐scale 3D structures. RuO 2 is a promising diffusion barrier for Ru interconnects owing to its compatibility with Ru ALD and its remarkable diffusion barrier properties. Herein, a RuO 2 diffusion barrier using an ALD process is developed. The highly reactive Ru precursor [tricarbonyl(trimethylenemethane)ruthenium] and improved O 2 supply enable RuO 2 deposition. The optimal process conditions [pulsing time ratio ( t O2 / t Ru ): 10, process pressure: 1 Torr, temperature: 180 °C] are established for the RuO 2 growth. Growth parameters, such as the growth rate (0.56 Å cycle –1 ), nucleation delay (incubation period: 6 cycles), and conformality (step coverage: 100%), are also confirmed on the SiO 2 substrate. The structural and electrical properties of the Ru/RuO 2 /Si multilayer are investigated to explore the diffusion barrier performance of the ALD‐RuO 2 film. The formation of Ru silicide does not occur without the conductivity degradation of the Ru/RuO 2 /Si multilayer with an increase in the annealing temperature up to 850 °C, thus demonstrating that interdiffusion of Ru and Si is completely suppressed by a thin (5 nm) ALD‐RuO 2 film. Consequently, the practical growth behavior and diffusion barrier performance of RuO 2 can serve as a potential diffusion barrier for Ru interconnects.