Electron-Induced Surface Reactions of η³-Allyl Ruthenium Tricarbonyl Bromide [(η³-C₃H₅)Ru(CO)₃Br]: Contrasting the Behavior of Different Ligands

Toward the goal of better understanding the elementary steps involved in the electron beam-induced deposition (EBID) of organometallic precursors, the present study is aimed at understanding the sequence of electron-stimulated reactions of surface-bound η 3 -allyl ruthenium tricarbonyl bromide [(η 3 -C 3 H 5 )Ru(CO) 3 Br], an organometallic complex with three different ligands: carbonyl (CO), halide (Br), and η 3 -allyl (η 3 -C 3 H 5 ). X-ray photoelectron spectroscopy and mass spectrometry were used in situ to probe the effects of 500 eV electrons on nanometer scale films of [(η 3 -C 3 H 5 )Ru(CO) 3 Br]. Initially, electron irradiation decomposes the precursor, reducing the central Ru atom and causing the ejection of CO ligands into the gas phase. Experimental evidence points to the inability of electron irradiation to remove the carbon atoms of the η 3 -allyl (η 3 -C 3 H 5 ) ligand from the resulting EBID deposits. Although the Br atoms are not labile in the initial molecular decomposition step, they are removed from the film after exposure to higher electron doses as a result of a slower, electron-stimulated desorption process. Comparative studies with [(η 3 -C 3 H 5 )Ru(CO) 3 Cl] reveal that the identity of the halogen does not influence the elementary reaction steps involved in the decomposition process. Collectively, results from these studies suggest that sufficiently volatile organometallic precursors with a small number of carbonyl and halide ligands could be used to generate deposits in EBID with significantly higher metal concentrations (and correspondingly lower levels of organic contamination) compared to existing EBID precursors.