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Focused electron beam induced processing (FEBIP) of volatile organometallic precursors has become an effective and versatile method of fabricating metal-containing nanostructures. However, the electron stimulated decomposition process responsible for the growth of these nanostructures traps much of the organic content from the precursor’s ligand architecture, resulting in deposits composed of metal atoms embedded in an organic matrix. To improve the metallic properties of FEBIP structures, the metal content must be improved. Toward this goal, the authors have studied the effect of atomic hydrogen (AH) and atomic oxygen (AO) on gold-containing deposits formed from the electron stimulated decomposition of the FEBIP precursor, dimethyl-(acetylacetonate) gold(III), AuIII(acac)Me2. The effect of AH and AO on nanometer thick gold-containing deposits was probed at room temperature using a combination of x-ray photoelectron spectroscopy (XPS), scanning Auger electron spectroscopy, and atomic force microscopy (AFM). XPS revealed that deposits formed by electron irradiation of AuIII(acac)Me2 are only ?10% gold, with ?80% carbon and ?10% oxygen. By exposing deposits to AH, all of the oxygen atoms and the majority of the carbon atoms were removed, ultimately producing a deposit composed of ?75% gold and ?25% carbon. In contrast, all of the carbon could be etched by exposing deposits to AO, although some gold atoms were also oxidized. However, oxygen was rapidly removed from these gold oxide species by subsequent exposure to AH, leaving behind purely metallic gold. AFM analysis revealed that during purification, removal of the organic contaminants was accompanied by a decrease in particle size, consistent with the idea that the radical treatment of the electron beam deposits produced close packed, gold particles. The results suggest that pure metallic structures can be formed by exposing metal-containing FEBIP deposits to a sequence of AO followed by AH., IST/Imaging Science and Technology, Applied Sciences

Electron beam induced deposition of organometallic precursors has emerged as an effective and versatile method for creating two-dimensional and three-dimensional metal-containing nanostructures. However, to improve the properties and optimize the chemical composition of nanostructures deposited in this way, the electron stimulated decomposition of the organometallic precursors must be better understood. To address this issue, we have employed an ultrahigh vacuum-surface science approach to study the electron induced reactions of dimethyl-(acetylacetonate) gold(III) [AuIII(acac)Me2] adsorbed onto solid substrates. Using thin molecular films adsorbed onto cooled substrates, surface reactions, reaction kinetics, and gas phase products were studied in the incident energy regime between 40 and 1500 eV using a combination of x-ray photoelectron spectroscopy (XPS), reflection absorption infrared spectroscopy (RAIRS), and mass spectrometry (MS). XPS and RAIRS data indicate that electron irradiation of AuIII(acac)Me2 is accompanied by the reduction in AuIII to a metallic Au0 species embedded in a dehydrogenated carbon matrix, while MS reveals the concomitant evolution of methane, ethane, carbon monoxide, and hydrogen. The electron stimulated decomposition of AuIII(acac)Me2 is first-order with respect to the surface coverage of the organometallic precursor, and exhibits a rate constant that is proportional to the electron flux. At an incident electron energy of 520 eV, the total reaction cross section was ? 3.6×10?16?cm2. As a function of the incident electron energy, the maximum deposition yield was observed at ?175 eV. The structure of discrete Au-containing deposits formed at room temperature by rastering an electron beam across a highly ordered pyrolytic graphite substrate in the presence of a constant partial pressure of AuIII(acac)Me2 was also investigated by atomic force microscopy., Imaging Science and Technology, Applied Sciences

The total cross section has been measured for the electron induced dissociation of trimethyl (methylcyclopentadienyl) platinum (IV) [MeCpPt(IV)Me3], a Pt precursor often used in focused electron beam induced processing (FEBIP), for incident electron energies ranging between 3–3 keV. Measurements were performed for the precursor in the adsorbed state under ultrahigh vacuum conditions. The techniques used in this study were temperature programmed desorption, x-ray photoelectron spectroscopy and mass spectrometry. Two surfaces were used in these experiments, amorphous carbon overlayers containing embedded Pt atoms (a:C-Pt), formed by the electron decomposition of the Pt precursor, and atomically clean Au. The results from these three experiments revealed a comparatively low total cross section at 8 eV (4.2+/-0.3xE?17 cm2 on the a:C-Pt and 1.4+/-0.1xE?17 cm2 on the Au) that increases with increasing incident electron energy, reaching a maximum at around 150 eV (4.1+/-0.5xE?16 cm2 on the a:C-Pt and 2.3+/-0.2xE?16 cm2 on the clean Au), before decreasing at higher incident electron energies, up to 3000 eV. Differences in the measured cross sections between Au and a:C-Pt surfaces demonstrate that the substrate can influence the reaction cross section of adsorbed species. Temperature programmed desorption was also used to measure the adsorption energy of MeCpPt(IV)Me3, which was found to depend on both the substrate and the adsorbate coverage. The work in this paper demonstrates that surface science techniques can be used to quantitatively determine the total cross section of adsorbed FEBIP precursors for electron induced dissociation as a function of incident electron energy. These total cross section values are necessary to obtain quantitatively accurate information from FEBIP models and to compare the reaction efficiencies of different precursors on a quantitative basis. (doi:10.1063/1.3225091), IST, Applied Sciences