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

Abstract

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.