Self-Catalyzed, Low-Temperature Atomic Layer Deposition of Ruthenium Metal Using Zero-Valent Ru(DMBD)(CO)₃ and Water

Abstract

Ruthenium (Ru) films are deposited using atomic layer deposition (ALD), promoted by a self-catalytic reaction mechanism. Using zero-valent, η 4 -2,3-dimethylbutadiene Ruthenium tricarbonyl (Ru(DMBD)(CO) 3 ) and H 2 O, Ru films are deposited at a rate of 0.1 nm/cycle. The temperature for steady deposition lies between 160 and 210 °C. Film structure and composition are confirmed via X-ray diffraction, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. The room-temperature electrical resistivity of 10 nm Ru films is found to be 39 μΩ• cm. In situ quadrupole mass spectrometry and density functional theory are used to understand ALD surface reactions. The ligand, dimethylbutadiene dissociatively desorbs on the surface. On the other hand, the carbonyl ligand is catalyzed by the Ru center. This leads to the water gas shift reaction, forming CO 2 and H 2 . Modulating deposition temperature affects these two ligand dissociation reactions. This in turn affects nucleation, growth, and hence, Ru film properties. Self-catalyzed reactions provide a pathway for low-temperature ALD with milder co-reactants.

Ultralow Loading Ruthenium on Alumina Monoliths for Facile, Highly Recyclable Reduction of p-Nitrophenol

“…The increase in pore radius after 75 cycles compared to the blank may be due to changes in the internal structure during ALD. Overall, the total pore volume decreased as the Ru deposition constricted the pores after ALD; this is consistent with prior literature [39,40]. The surface morphology of Ru 75 @Al 2 O 3 was imaged by Scanning Electron Microscopy (SEM) (Figure 1D,E).…”

“…Growth was achieved utilizing an A-B cycle of alternating η4-2,3-dimethylbutadiene ruthenium tricarbonyl (Ru(DMBD)(CO) 3 ) as a zero-valent ruthenium precursor and water as a co-reactant (Figure 1B). Previous work from one of our groups has shown this specific process to produce metallic Ru [39]. Using A-B cycle sets of 50 and 75, two different materials were prepared: denoted as Ru 50 @Al 2 O 3 and Ru 75 @Al 2 O 3 , respectively.…”

“…ALD: Atomic layer deposition of ruthenium was performed using a home-built system coupled with a downstream quadrupole mass spectrometer (QMS), as described in our previous work [39,[54][55][56]. Briefly, we used a load-locked, hot-wall, viscous flow reactor, 24 in.…”

“…ALD-synthesized catalysts have been previously studied for hydrolysis reactions [29][30][31]; notably, Jiang et al reported the use of an ALD-Ni coated catalyst for nitrophenol reduction [32]. Ruthenium was chosen due to its well-established catalytic activity in reduction reactions [33][34][35][36][37][38], lower cost compared to Pd and Au catalysts which dominate nitroaromatic reductions, and the availability of a well-defined ALD process for Ru films, as developed by one of our groups [39]. The ALD-Ru on alumina monolith catalysts is highly active, exhibiting reaction rates competitive with precious metal catalysts, and is recyclable for up to five trials as tested with no significant loss in activity from trials 2 to 5.…”

Atomic layer deposition of ruthenium using an ABC-type process: Role of oxygen exposure during nucleation

“…25,35,36 To date, a variety of Ru precursors have been examined for Ru ALD including metallocenes, β-diketonates and their derivatives, 25 and recently, zerovalent precursors. 12,[37][38][39] Typically, Ru ALD from metallocene or β-diketonate precursors suffers from long nucleation delays. 25 In addition to requiring a longer process time, recipes with long nucleation delays can result in films with rough interfaces as a result of island formation during the initial growth.…”