The principle of focused electron beam induced processing (FEBIP) is based on the dissociation of surface-adsorbed gas molecules under the influence of an electron beam (typically 1-30 keV). The precursor molecules are thus dissociated into volatile and non-volatile products. Depending on the type of precursor, the non-volatile components adhere to the substrate (in the case of deposition (FEBID)) or react with the substrate and form volatile species (in the case of etching (FEBIE)) [1]. Since primary electrons, by interacting with the substrate, produce low-energy secondary electrons (SEs), there is considerable interest in identifying the mechanisms by which primary and secondary electrons dissociate precursor molecules [2]. SEs are expected to play a significant role in the decomposition of adsorbed molecules via processes such as dissociative electron attachment or dipolar dissociation, but primary electrons are reported in some cases to contribute to or even dominate the dissociation process. The aim of this work is to determine the role of low-energy electrons (LEEs: < 25 eV) in the dissociation of surface-adsorbed Fe(CO)5, which is a common organometallic precursor for FEBID. It is frequently reported that the FEBID of condensed Fe(CO)5 results in the deposition of Fe via the progressive elimination of CO, but the details of the mechanism of Fe(CO)5 dissociation remains to be determined [3]. Using an electron stimulated desorption (ESD) system consisting of an electron gun and a time-of-flight mass spectrometer [4], we have studied the emission of charged fragments from thin films of Fe(CO)5  condensed on Pt or on Xe (to isolate the Fe(CO)5 film from the influence of the metallic substrate), as a function of electron energy (4-22 eV). Preliminary results suggest that the main loss from Fe(CO)5 is via loss of O- anions, but other fragments were detected, suggesting that Fe(CO)5 dissociates by emission of CO, via one-electron events (e.g., dissociative electron attachment or dipolar dissociation) at LEE energies of 5 eV or higher, producing Fe(CO)xanion fragments.[1] I. Utke, P. Hoffmann, J. Melngailis, J. Vac. Sci. Technol. B 26 , 1071 (2008).[2] W. F. van Dorp, C. W. Hagen, J. Appl. Phys. 104 , 081301 (2008).[3] C. Hauchard, P. A. Rowntree, Can. J. Chem., 89 , 1163-1173 (2011).[4] M. N. Hedhili, P. Cloutier, A. D. Bass, T. E. Madey and L. Sanche, J. Chem. Phys. 125 , 094704 (2006).

Electron stimulated desorption study of the electron-induced degradation of condensed Fe(CO)<sub>5</sub> films in the 4-22 eV energy range

248th National Meeting (2014)

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Electron stimulated desorption study of the electron-induced degradation of condensed Fe(CO)5 films in the 4-22 eV energy range

Electron stimulated desorption study of the electron-induced degradation of condensed Fe(CO)₅ films in the 4-22 eV energy range