Model improvements to simulate charging in scanning electron microscope

Abstract

Background: Charging of insulators is a complex phenomenon to simulate since the accuracy of the simulations is very sensitive to the interaction of electrons with matter and electric fields. Aim: In this study, we report model improvements for a previously developed Monte-Carlo simulator to more accurately simulate samples that charge. Approach: The improvements include both modeling of low energy electron scattering by first-principle approaches and charging of insulators by the redistribution of the charge carriers in the material with an electron beam-induced conductivity and a dielectric breakdown model. Results: The first-principle scattering models provide a more realistic charge distribution cloud in the material and a better match between noncharging simulations and experimental results. The improvements on the charging models, which mainly focus on the redistribution of the charge carriers, lead to a smoother distribution of the charges and better experimental agreement of charging simulations. Conclusions: Combined with a more accurate tracing of low energy electrons in the electric field, we managed to reproduce the dynamically changing charging contrast due to an induced positive surface potential.

Local voltage contrast changes in MOSFET using scanning electron microscopy with photoelectron beam technology

“…According to a report by K. T. Arat et al 4,5 , the simulated equilibrium state is reached such that δ ~ 1 for SiO2 in positive charging mode. On the other hand, in a report by T. Thome et al, 6 when the irradiation current density is increased, δ of Al2O3 in the equilibrium state becomes less than 1.…”

Reaction-diffusion effects and spatiotemporal oscillations under SEM, STM and AFM-assisted charging in fiber-like and wire-like systems: From molecular and quantum wires to cooperative ferroelectric nanofibers and microfibers

“…The local dielectric charging induced by the line scanning during SEM observation is a well known phenomenon, which can be simulated using simple mathematical/statistical physical approaches [25,26] (including those approved by the standards of NIST (National Institute of Standards and Technology [27] )). The electric charging of electron microscopic specimens has been actively studied from 1960s or 1970s [28,29] .…”

Electron microscopy in semiconductor inspection

“…The charging phenomenon shows a dynamically changing contrast. Arat et al [22] have introduced two physical mechanisms into the simulation to perform dynamic charging accurately in the Monte Carlo simulation. The first is the introduction of a first-principles scattering model into the interaction mechanism between PE and specimen material.…”