| AVS 58th Annual International Symposium and Exhibition | |
| Surface Science Division | Monday Sessions |
| Session SS1-MoA |
| Session: | Selectivity and Reactivity of Chemisorbed Species |
| Presenter: | Howard Fairbrother, Johns Hopkins University |
| Authors: | H. Fairbrother, Johns Hopkins University S. Rosenberg, Johns Hopkins University J. Wnuk, Johns Hopkins University C. Hagen, Delft University of Technology, Netherlands W. vanDorp, Delft University of Technology, Netherlands K. Landheer, Delft University of Technology, Netherlands |
| Correspondent: | Click to Email |
Electron beam induced deposition (EBID) is a direct-write lithographic technique where volatile organometallic precursors are decomposed by a focused electron beam in a low vacuum environment to create metallic nanostructures. As a tool for nanofabrication, EBID offers an attractive and unique combination of capabilities including high spatial resolution and the flexibility to deposit free-standing three-dimensional structures without the need for resist layers. However, a major limitation of EBID is that nanostructures deposited from organometallic precursors typically possess unacceptable levels of organic contamination. To overcome this limitation it is crucial to develop a more detailed and fundamental understanding of how adsorbed organometallics undergo electron stimulated decomposition. Using a selected suite of organometallic precursors used in EBID (CH3CpPt(CH3)3), Pt(PF3)4 and W(CO)6) I will describe how a surface science approach has been used to provide mechanistic and kinetic insights into EBID and to identify key structure-reactivity relationships. Central to our findings is the observation that for many organometallic precursors, EBID is initiated by the cleavage of a single metal-ligand bond and the release of the free ligand into the gas phase. However, subsequent electron stimulated reactions are characterized by decomposition rather than desorption of the residual ligands. Rationale design criteria for new organometallics which will decompose to produce metallic nanostructures with greater metallic purity have also been developed, such as the need to avoid using cyclopentadienyl ligands. In related studies we have also identified and rationalized the often significant effect that substrate temperature exerts on the composition of EBID materials created from organometallic precursors. Specifically, increased purity is expected for EBID films deposited at high substrate temperatures and low electron fluxes; the same conditions that reduce growth rates.