| AVS 56th International Symposium & Exhibition | |
| Surface Science | Tuesday Sessions |
| Session SS1+PS+TF+AS+NS-TuA |
| Session: | Non-Thermal Chemistry / Ion, Electron Processes |
| Presenter: | H. Fairbrother, Johns Hopkins University |
| Authors: | H. Fairbrother, Johns Hopkins University J. Wnuk, Johns Hopkins University J. Gorham, Johns Hopkins University S. Rosenberg, Johns Hopkins University T. Madey, Rutgers W.F. van Dorp, Delft University of Technology, The Netherlands K. Hagen, Delft University of Technology, The Netherlands |
| Correspondent: | Click to Email |
Focused electron beam induced processing (FEBIP) of volatile organometallic precursors has emerged as an effective and versatile method of fabricating metal-containing nanostructures. However, to improve the materials properties of FEBIP nanostructures, provide information that can aid in the rational design of new precursors and improve the modeling of the FEBIP process it is necessary to better understand the molecular level processes associated with the electron stimulated decomposition of organometallic precursors. To address this issue, we have employed a UHV-surface science approach to study the electron induced reactions of dimethyl(acetylacetonate) gold(III) (Au(acac)Me2), a common precursor used for Au deposition in FEBIP, adsorbed on solid substrates. Surface reactions, reaction kinetics and gas phase products were studied using incident electrons in the energy regime between 40-1500 eV, using a combination of XPS, RAIRS and MS. XPS data indicate that electron irradiation of AuIII(acac)Me2 is accompanied by the reduction of AuIII to a metallic Au0 species embedded in a carbon matrix while MS reveals the concomitant evolution of methane, ethane and hydrogen. The electron stimulated decomposition of the AuIII(acac)Me2 precursor can be described by a first-order decay process with respect to the surface coverage, with a rate constant that is proportional to the electron flux and a total reaction cross-section of ≈3.6 x 10-16 cm2 at an incident electron energy of 520 eV. As a function of the incident electron energy, the maximum deposition yield was observed at ≈175 eV. Our results are consistent with the idea that those carbon atoms removed as volatile species from the AuIII(acac)Me2 precursor during FEBIP are associated with methyl groups attached to the central Au atom. In related studies we also studied the effects of atomic oxygen and atomic hydrogen on Au-containing carbonaceous films deposited by electron beam irradiation of Au(acac)Me2, as a potential route to purify FEBIP deposits. Atomic oxygen was found to be the more effective of the two radical treatments in removing carbon, although a surface layer of gold oxide was formed. Subsequent exposure of this overlayer to atomic hydrogen rapidly removed the oxide, resulting in a pure Au film. AFM analysis of FEBIP deposits before and after radical treatment support the idea that carbon abatement is accompanied by a decrease in particle size.