DFT modeling of atomic layer deposition of Ru interconnect metal for EUV scaling

Density functional theory (DFT) simulations have been applied to understand the surface reaction mechanisms for the selective deposition of Ru metal for use in vias or interconnects. Ruthenium-ALD with bis-(ethylcyclopentadienyl)-ruthenium [Ru(EtCp)(2)] and O-2 as reactants shows promising surface selectivity but necessitates activation steps for desorption of ligands to complete each ALD cycle. DFT modeling of Ru(EtCp)(2) on Ru surfaces reveals that ALD processes are limited by the strong aromatic-ring interaction with the metallic surface. Introduction of atomic H as a nonoxidizing co-reactant gas in place of O-2 can overcome these barriers by saturation of the Cp pi-bonds, weakening the bonds to the metallic Ru surface. This study aims to provide a comprehensive understanding of leveraging ligand-surface, surface-hydrogen, and ligand-hydrogen interactions to achieve oxygen-free ALD with the Ru(EtCp)(2) precursor at moderate to low temperatures.

Automated summary

Density functional theory (DFT) simulations were used to investigate the surface reaction mechanisms of selective deposition of Ru metal using Ru(EtCp)(2) and O-2 as reactants. The study found that the ALD processes were limited by the strong interaction between the aromatic ring and the metallic surface. Introducing atomic H as a nonoxidizing co-reactant gas can overcome these limitations by saturating the Cp pi-bonds and weakening the bonds to the Ru surface. This study aims to provide a comprehensive understanding of leveraging ligand-surface, surface-hydrogen, and ligand-hydrogen interactions for oxygen-free ALD with the Ru(EtCp)(2) precursor at moderate to low temperatures.