Improvements in Growth Behavior of CVD Ru Films on Film Substrates for Memory Capacitor Integration

Ru thin films were grown by metallorganic chemical vapor deposition using a cyclopentadienylpropylcyclopentadienlylruthenium(II) on the Ta2O5, TiN, Si3N4, SiO2, TiO2 thin-film substrates and their nucleation and growth behaviors were investigated. It was observed that the bonding type between atoms of the substrate thin films has a profound effect on the nucleation behaviors. The more ionic the bonding, the smaller the nucleation barrier and smoother Ru films were obtained. The poor nucleation property of Ru films on TiN, which has a covalent bonding nature, was successfully improved by the Ar-plasma treatment on TiN substrate prior to the deposition of Ru film. It was found that the Ar plasma treatment selectively removes N ions from the surface and made the TiN surface more metallic or ionic (due to the residual Ti-O bonding) and reduced the nucleation barrier. Furthermore, oxidation resistance of Ru/TiN layers was improved by H2 annealing due to the densification of the Ru films.