Area-Selective Atomic Layer Deposition of Ruthenium via Reduction of Interfacial Oxidation

Abstract

Achieving atomic-scale precise control over material layering is critical for the development of future semiconductor technology. Area-selective deposition (ASD) has emerged as an indispensable tool for crafting semiconductor components and structures via bottom-up pattern transfer. Ruthenium has attracted significant interest as a low-resistivity conducting material for next-generation interconnect technology. However, the oxidative counter-reactants such as O2 often used for atomic layer deposition (ALD) of metallic Ru films result in a considerable increase in contact resistance because of substrate oxidation, limiting the applications of both ALD and ASD of Ru. In this study, Ru ASD is demonstrated using two-step ALD with the sequential use of H2 and O2 as counter-reactants and dimethylamino-trimethylsilane (DMATMS) as a precursor inhibitor. Both theoretical and experimental results demonstrate that in the two-step Ru ALD, the oxide layer can be eliminated via the reduction of the oxidized substrate metal surface by the H2 counter-reactant. This mechanism simultaneously facilitates the adsorption of the Ru precursor (tricarbonyl-(trimethylenemethane)-ruthenium) and removal of the surface oxide layer. Consequently, Ru growth is suppressed on the DMATMS-inhibited SiO2 surface during ASD, enabling exclusive deposition of Ru on the Mo surface. The currently proposed Ru ASD scheme using two-step ALD is highly promising for driving advancements in interconnect technology for commercial applications.