Atomic layer deposition of Ru thin film using N2/H2 plasma as a reactant

Ruthenium (Ru) thin films were grown by atomic layer deposition using IMBCHRu [(η6-1-Isopropyl-4-MethylBenzene)(η4-CycloHexa-1,3-diene)Ruthenium(0)] as a precursor and a nitrogen–hydrogen mixture (N2/H2) plasma as a reactant, at the substrate temperature of 270 °C. In the wide range of the ratios of N2 and total gas flow rates (fN2/N2 + H2) from 0.12 to 0.70, pure Ru films with negligible nitrogen incorporation of 0.5 at.% were obtained, with resistivities ranging from ∼ 20 to ∼ 30 μΩ cm. A growth rate of 0.057 nm/cycle and negligible incubation cycle for the growth on SiO2 was observed, indicating the fast nucleation of Ru. The Ru films formed polycrystalline and columnar grain structures with a hexagonal-close-packed phase. Its resistivity was dependent on the crystallinity, which could be controlled by varying the deposition parameters such as plasma power and pulsing time. Cu was electroplated on a 10-nm-thick Ru film. Interestingly, it was found that the nitrogen could be incorporated into Ru at a higher reactant gas ratio of 0.86. The N-incorporated Ru film (∼ 20 at.% of N) formed a nanocrystalline and non-columnar grain structure with the resistivity of ∼ 340 μΩ cm. - Highlights: ► Atomic layer deposition (ALD) of Ru and N-incorporated Ru film using N2/H2 plasma. ► The growth rate of 0.057 nm/cycle and negligible incubation cycle. ► A low resistivity of Ru (∼ 16.5 μΩ cm) at the deposition temperature of 270 °C. ► Electroplating of Cu on a 10-nm-thick ALD-Ru film.