Electron beam deposition for nanofabrication: Insights from surface science

• Published in: Surface science Vol. 605; no. 3; pp. 257 - 266
• Main Authors: Wnuk, J.D., Rosenberg, S.G., Gorham, J.M., van Dorp, W.F., Hagen, C.W., Fairbrother, D.H.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 01.02.2011; Elsevier
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Electron beam induced deposition; Electron microscopy; Electron–molecule interactions; Electron–solid interactions; Exact sciences and technology; Mass spectrometry; Organometallics; Photoelectron spectroscopy; Physics; Organometallics; Electron beam induced deposition; Electron–molecule interactions; Electron–solid interactions; Electron microscopy; Photoelectron spectroscopy; Mass spectrometry; Electron-molecule interactions; Electron-solid interactions; Electron beam deposition
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2010.10.035

Electron beam induced deposition (EBID) is a direct-write lithographic technique that utilizes the dissociation of volatile precursors by a focused electron beam in a low vacuum environment to create nanostructures. Notable advantages of EBID over competing lithographic techniques are that it is a single step process that allows three-dimensional free-standing structures to be created, including features with single-nanometer scale dimensions. However, despite the inherent advantages of EBID, scientific and technological issues are impeding its development as an industrial nanofabrication tool. Perhaps the greatest single limitation of EBID is that metal-containing nanostructures deposited from organometallic precursors typically possess unacceptable levels of organic contamination which adversely affects the material's properties. In addition to the issue of purity, there is also a lack of understanding and quantitative information on the fundamental surface reactions and reaction cross-sections that are responsible for EBID. In this prospective, we describe how surface analytical techniques have begun to provide mechanistic and kinetic insights into the molecular level processes associated with EBID. This has been achieved by observing the effect of electron irradiation on nanometer thick films of organometallic precursors adsorbed onto solid substrates at low temperatures (< 200 K) under ultra-high vacuum conditions. Experimental observations include probing changes in surface composition, metal oxidation state, and the evolution of volatile species. Insights into surface reactions associated with purification strategies are also detailed. We also discuss unresolved scientific challenges and opportunities for future EBID research. ► Surface analytical techniques provide mechanistic insights into electron stimulated processes. ► Organometallic precursors undergo electron initiated metal-ligand bond cleavage. ► Total reaction cross-sections for adsorbed precursor species have been quantified. ► Atomic radicals successfully abate organic impurities in metal deposits.