Identifying the crossover between growth regimes via in-situ conductance measurements in focused electron beam induced deposition

Abstract

Focused electron beam induced deposition presents a promising technique for the fabrication of nanostructures. However, due to the dissociation of mostly organometallic precursor molecules employed for the deposition process, prepared nanostructures contain organic residues leading to rather low conductance of the deposits. Post-growth treatment of the structures by electron irradiation or in reactive atmospheres at elevated temperatures can be applied to purify the samples. Recently, an in-situ conductance optimization process involving evolutionary genetic algorithm techniques has been introduced leading to an increase of conductance by one order of magnitude for tungsten-based deposits using the precursor W(CO)6. This method even allows for the optimization of conductance of nano-structures for which post-growth treatment is not possible or desirable. However, the mechanisms responsible for the observed enhancement have not been studied in depth. In this work, we identified the dwell-time dependent change of conductivity of the samples to be the major contributor to the change of conductance. Specifically, the chemical composition drastically changes with a variation of dwelltime resulting in an increase of the metal content by 15 at% for short dwell-times. The relative change of growth rate amounts to less than 25 % and has a negligible influence on conductance. We anticipate the in-situ genetic algorithm optimization procedure to be of high relevance for new developments regarding binary or ternary systems prepared by focused electron or ion beam induced deposition.

Electron interactions with the heteronuclear carbonyl precursor H2FeRu3(CO)13 and comparison with HFeCo3(CO)12: from fundamental gas phase and surface science studies to focused electron beam induced deposition

“…Considering the extremely pronounced edge bulging for the short dwell time of 200 ns and the rounded shape for longer dwell times (500 µs), we attribute these morphological changes to a transition from a reaction-rate limited (RRL) to a mass-transport limited (MTL) regime with increasing dwell time. This is analogous to our previous results for the precursor W(CO) 6 described in [ 91 ]. For short dwell times the dish-shape is particularly strongly pronounced and does in fact lead to a lateral inflation of the targeted size by a factor of two.…”

Superconductivity in the system MoxCyGazOδ prepared by focused ion beam induced deposition

“…Details of this procedure can be found in 8 . In particular, for FEBID structures prepared with the precursor W(CO) 6 we could show, that the optimized deposition parameter set does indeed lead to deposits with the largest conduc-tivity and that parameter-dependent changes of the overall growth rate are rather insignificant 8,12,13 . Based on these findings we employed this optimization scheme here for FIBID and identified the dwell time and pitch parameters that were used for sample 6.…”

Superconductivity in the system $\rm Mo_xC_yGa_zO_δ$ prepared by focused ion beam induced deposition

“…Details of this procedure can be found in 8 . In particular, for FEBID structures prepared with the precursor W(CO) 6 we could show, that the optimized deposition parameter set does indeed lead to deposits with the largest conduc-tivity and that parameter-dependent changes of the overall growth rate are rather insignificant 8,12,13 . Based on these findings we employed this optimization scheme here for FIBID and identified the dwell time and pitch parameters that were used for sample 6.…”