Self‐Formation of a Ru/ZnO Multifunctional Bilayer for the Next‐Generation Interconnect Technology via Area‐Selective Atomic Layer Deposition
Yuki Mori, Taehoon Cheon, Yohei Kotsugi, Youn‐Hye Kim, Yejin Park, Mohd Zahid Ansari, Debananda Mohapatra, Yujin Jang, Jong‐Seong Bae, Woobin Kwon, Gahui Kim, Young‐Bae Park, Han‐Bo‐Ram Lee, Wooseok Song, Soo‐Hyun Kim
Abstract
Abstract This study suggests a Ru/ZnO bilayer grown using area‐selective atomic layer deposition (AS‐ALD) as a multifunctional layer for advanced Cu metallization. As a diffusion barrier and glue layer, ZnO is selectively grown on SiO 2 , excluding Cu, where Ru, as a liner and seed layer, is grown on both surfaces. Dodecanethiol (DDT) is used as an inhibitor for the AS‐ALD of ZnO using diethylzinc and H 2 O at 120 °C. H 2 plasma treatment removes the DDT adsorbed on Cu, forming inhibitor‐free surfaces. The ALD‐Ru film is then successfully deposited at 220 °C using tricarbonyl(trimethylenemethane)ruthenium and O 2 . The Cu/bilayer/Si structural and electrical properties are investigated to determine the diffusion barrier performance of the bilayer film. Copper silicide is not formed without the conductivity degradation of the Cu/bilayer/Si structure, even after annealing at 700 °C. The effect of ZnO on the Ru/SiO 2 structure interfacial adhesion energy is investigated using a double‐cantilever‐beam test and is found to increase with ZnO between Ru and SiO 2 . Consequently, the Ru/ZnO bilayer can be a multifunctional layer for advanced Cu interconnects. Additionally, the formation of a bottomless barrier by eliminating ZnO on the via bottom, or Cu, is expected to decrease the via resistance for the ever‐shrinking Cu lines.