AVS 61st International Symposium & Exhibition
    Surface Science Monday Sessions
       Session SS+AS+EN-MoM

Paper SS+AS+EN-MoM11
Electron Beam Induced Surface Reactions of Adsorbed π-allyl Ruthenium Tricarbonyl Bromide: Towards the Design of Precursors Specifically for Electron Beam Induced Deposition

Monday, November 10, 2014, 11:40 am, Room 309

Session: Mechanistic Insights into Surface Reactions: Catalysis, ALD, etc.
Presenter: Julie Spencer, Johns Hopkins University
Authors: J.A. Spencer, Johns Hopkins University
R.G. Thorman, University of Iceland
M.S. Barclay, Johns Hopkins University
J.A. Brannaka, University of Florida
O. Ingólfsson, University of Iceland
L. McElwee-White, University of Florida
D.H. Fairbrother, Johns Hopkins University
Correspondent: Click to Email
This surface science study focuses on elucidating the electron stimulated elementary reactions involved in Electron Beam Induced Deposition (EBID) of π-allyl ruthenium tricarbonyl bromide (π-C3H5Ru(CO)3Br), an organometallic precursor synthesized specifically to test its suitability as an EBID precursor. EBID is a minimally invasive, resistless lithographic process which uses the electron stimulated decomposition of volatile organometallics under low vacuum conditions to fabricate and prototype three-dimensional metallic nanostructures. To date, EBID of nanostructures has used precursors designed for thermal processes, such as chemical vapor deposition (CVD). However, precursors that yield pure metal deposits in CVD often create EBID deposits with high levels of organic contamination which severely limits the range of potential applications for EBID nanostructures, highlighting the need to better understand how the structure of organometallics influences their electron stimulated reactions. To address this knowledge gap we have conducted ultra-high vacuum (UHV) surface science studies to probe the effects of 500eV electrons on nanometer scale films of organometallics adsorbed on inert substrates at low temperatures using X-ray Photoelectron Spectrometry and Mass spectrometry. Recently, we have collaborated with synthetic organometallic chemists to study organometallic complexes not designed for CVD to test specific hypotheses about how the EBID process occurs; the first example of this new collaboration is π-allyl ruthenium tricarbonyl bromide (π-C3H5Ru(CO)3Br). Experimental results indicate that electron stimulated decomposition of π-C3H5Ru(CO)3Br causes the central Ru atom to become reduced and in the process causes the vast majority of the carbonyl ligands to be ejected into the gas phase, with no loss of Br or the carbon atoms in the π-allyl ligand. A parallel study of π-C3H5Ru(CO)3Cl indicated that the identity of the halogen does not affect the decomposition process. However, although halogen atoms are not labile in the initial decomposition step, they can be removed by a slower electron stimulated desorption process at higher electron fluxes more representative of those encountered in typical EBID experiments which are conducted in electron microscopes. Collectively, these results suggest that organometallic precursors whose ligand architecture contains a combination of carbonyl and halogen ligands could be used to create EBID deposits with higher metal contents than are currently possible. To test this hypothesis we will also present results on the behavior of cis-dicarbonyldichloro platinum(II), cis-PtCl2(CO)2.