Ru as an alternative material for advanced contacts

This paper introduces Ru as an alternative material for filling narrow MOL trenches. We show a non-closed layer of TiN (or TiO x ) as thin as 0.3nm can provide sufficient adhesion into surrounding SiO 2 dielectric to enable defect free planarization steps. The resistance of a Ru filled via on this 0.3nm TiN liner (labeled as barrier-less) outperforms the Co filled equivalent process. On planar test structures fabricated on both p-SiGe and n-Si, we confirm resistivity of the contact interface to be independent of the fill metal choice. Finally we confirm a ALD and CVD based Ru fill process can fill high aspect ratio trenches as narrow as 10nm. This makes barrier-less Ru a potential candidate for replacing TiN/Co for advanced nodes.