Area-Selective Atomic Layer Deposition of Ruthenium Using a Novel Ru Precursor and H₂O as a Reactant

Ruthenium (Ru) has drawn attention in the field of future semiconductor processing as a diffusion barrier layer and an electrode material. Here, ruthenium films are deposited by atomic layer deposition (ALD) using a novel precursor, Ru₂{μ₂-η³-N­(tBu)–C­(H)–C­(iPr)}­(CO)₆ (T-Rudic), and two different co-reagents, that is, H₂O and O₂. Ru films are deposited at 0.1 Å/cycle at 150 °C with H₂O and 0.8 Å/cycle at 200 °C with O₂. The H₂O reactant set exhibits ALD saturation between 150 and 200 °C. However, the O₂ reactant set shows a linear incremental growth rate over 200 °C and nongrowth under 175 °C. Film growth preference is observed on various substrates (e.g., Si, SiO₂, Al₂O₃, and graphitic carbon) when the H₂O reactant is applied at 150 °C. Both experimental data and density functional theory calculations indicate that preferential growth occurs on a hydrogen-terminated surface (Si) rather than a hydroxyl-terminated surface (SiO₂). The Auger electron spectroscopy mapping image of a selectively deposited Ru film on a patterned Si and SiO₂ substrate supports that this selective deposition mechanism also occurs in a square-patterned substrate.