The role of electron-stimulated desorption in focused electron beam induced deposition

Abstract

SummaryWe present the results of our study about the deposition rate of focused electron beam induced processing (FEBIP) as a function of the substrate temperature with the substrate being an electron-transparent amorphous carbon membrane. When W(CO)6 is used as a precursor it is observed that the growth rate is lower at higher substrate temperatures. From Arrhenius plots we calculated the activation energy for desorption, E des, of W(CO)6. We found an average value for E des of 20.3 kJ or 0.21 eV, which is 2.5–3.0 times lower than literature values. This difference between estimates for E des from FEBIP experiments compared to literature values is consistent with earlier findings by other authors. The discrepancy is attributed to electron-stimulated desorption, which is known to occur during electron irradiation. The data suggest that, of the W(CO)6 molecules that are affected by the electron irradiation, the majority desorbs from the surface rather than dissociates to contribute to the deposit. It is important to take this into account during FEBIP experiments, for instance when determining fundamental process parameters such as the activation energy for desorption.

Localized Probing of Gas Molecule Adsorption Energies and Desorption Attempt Frequencies

“…19 It was, however, attributed to electron stimulated desorption (ESD) 15,19 rather than the phenomenon of adsorbate depletion which is inherent to EBID. ESD causes the adsorbate concentration (N a ) to decrease at a rate σ E f, where σ E is the cross-section for ESD.…”

“…19 These observations were attributed to electron stimulated desorption. 15,19 Here we show that Arrhenius analyses of EBID rates yield activation energies and pre-exponential factors that are expected to scale with current (and other parameters) and explain these dependencies using established models of EBID rate kinetics. We define conditions under which the activation energies and prefactors correspond to E a and k 0 , respectively.…”

Charging of carbon thin films in scanning and phase-plate transmission electron microscopy

“…However, SEs generated in the thin film have typical kinetic energies of up to 100 eV and thus can induce ESD. ESD indeed plays an important role in focused electron-beam induced processing (FEBIP) where electronbeam illumination is used in combination with suitable precursor gases to, e.g., deposit or etch nm sized structures on sample surfaces [35][36][37].…”

Lateral resolution in focused electron beam-induced deposition: scaling laws for pulsed and static exposure

“…Simultaneous co-adsorption of two precursor gases for deposition without taking surface diffusion into account was studied in [22,23]. Specific phenomena which may appear during the FEBID process, like chemisorption or electron-stimulated desorption of adsorbates, were proposed in [24] and [25], respectively.…”