Growth behavior and mechanism of atomic layer deposition of Ru for replacing Cu-interconnects

The growth behavior and nucleation mechanism of Ru films on various substrates using Ru(EtCp)2 as the precursor and O2 as the reactant were studied systematically. The results show that the Ru films grow rapidly on TiN substrates with almost no incubation time. Different of the segregation and combustion mechanism reported in the previous literature, we established the adsorption and combustion mechanism of ALD-Ru on TiN substrates. SEM and XPS confirmed that the grown Ru films were polycrystalline (average grain size of 16.53 nm, negligible impurities). The Ru films annealed at 600 °C showed significantly low resistivity of 9.73 μΩ•cm, which is one of the lowest resistivities reported in the literature so far. Suppressing electron scattering at grain boundaries is crucial factor to preparing Ru films with low resistivity. The work uses a simple plasma-free technique to construct high-quality Ru films with extremely low resistivity and low impurities, making them one of the ideal candidates for replacing Cu in future ultrafine-pitch interconnects. Furthermore, the work is significant for understanding the growth behaviors and nucleation mechanisms of Ru films on different substrates.