Chemistry of Ruthenium Diketonate Atomic Layer Deposition (ALD) Precursors on Metal Surfaces

The thermal chemistry of tris(2,2,6,6-tetramethyl-3,5-heptanedionato)ruthenium(III) (Ru(tmhd)3), a potential precursor for the chemical deposition of ruthenium -containing films, on Ni(110) single-crystal surfaces was characterized by using a combination of temperature-programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS), and reflection–absorption infrared spectroscopy (RAIRS). Additional characterization of the surface chemistry of the protonated ligand, Htmhd, was evaluated as well for reference. It was found that the molecularly adsorbed ruthenium compound reacts readily by approximately 310 K, loosing its ligands to both the gas phase and the surface as the central ion is reduced to its Ru0 metallic state. The diketonate ligand, now bonded to the nickel surface, starts to decompose at around 400 K, and generates gas-phase carbon monoxide and molecular hydrogen in TPD peaks at 435 K. More extensive decomposition is seen at 535 K, yielding 2,2-dimethyl-3-oxopentanal, isobutene, ketene, an...