Ruthenium for Subtractive and Semi-Damascene Processes of Interconnects Formation

Abstract Ruthenium thin films were deposited by plasma enhanced atomic layer deposition (PEALD) using Ru(EtCp)2 and oxygen plasma on the modified silicon surface and SiO2/Si substrates. The substrate temperature has a significant impact on film growth. The GXRD and SIMS analysis have shown that at the substrate temperature T = 375°C there is a sharp change in the mechanisms of surface reactions, which leads to a change in the film composition from RuO2 at low temperatures to a pure Ru film at higher temperatures. This was confirmed by measurements of the electrical resistivity of Ru-based films. The lowest surface roughness ~1.5 nm was obtained at a film thickness of 29 nm deposited at 375°C on a SiO2/Si-substrate. The measured resistivity of the Ru film was 18–19 μΩ cm. Issues regarding the plasma-chemical etching of ruthenium and the spin-on of a low-k dielectric onto arrays of lines are taken into account.