Atomic Layer Deposited RuO<sub>2</sub> Diffusion Barrier for Next Generation Ru‐Interconnects
Youn‐Hye Kim, Minsu Kim, Yohei Kotsugi, Taehoon Cheon, Debananda Mohapatra, Yujin Jang, Jong‐Seong Bae, Tae Eun Hong, Rahul Ramesh, Ki‐Seok An, Soo‐Hyun Kim
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.