A TRIDYN study: Comparison of experimental SIMS useful yields with simulated Cs concentration evolution

Abstract

In a previous paper by the same authors, the sensitivity variations of negative secondary ions during Secondary Ion Mass Spectrometry (SIMS) analysis have been studied with respect to conditions of neutral cesium deposition. An experimental determination of the Cs surface concentration was impossible and it has been described by characteristic parameters. In this paper, the TRIDYN model is used to simulate these surface concentrations with respect to the different conditions used in the experimental study. The simulations give implantation profiles as well as sputtering yields of the involved elements with respect to the primary ion fluence. For the different experimental conditions, the implantation profiles at steady state are used to calculate mean Cs surface concentrations that have been averaged over different depths. The sensitivities of negative secondary ions can now be plotted with respect to these concentrations and experimental and simulated results can be compared to the electron-tunneling model describing ion emission from metallic and semi-conducting samples. Nevertheless, approximations included in this simulation model induce some artefacts which are discussed in this paper.