Simulation of Silicon Carbide Sputtering by a Focused Gallium Ion Beam

Abstract—

The precision fabrication of microstructures and nanostructures by the focused-ion-beam method is significantly simplified by the simulation of sputtering of materials by accelerated ions. A widely used approach to such simulation is the Monte Carlo method, which, to be correctly used, requires data on the surface binding energy of sample atoms. In this study, to obtain data on the surface binding energy for silicon carbide, test structures in the form of rectangular areas sputtered using gallium ions with a dose of 10¹⁷ cm^–2 are fabricated. Their cross sections are studied by transmission electron microscopy and energy-dispersive X‑ray microanalysis. The average gallium concentration in the vicinity of its maximum is found to be ${{\langle {{C}_{{{\text{Ga}}}}}\rangle }_{{\exp }}}$ = 25 at %. This value and a sputtering yield of Y_exp = 2.1 are used for comparison with the results of calculation in the SDTrimSP 5.07 software package using the R factor. The comparison is made using available continuous and discrete models and the proposed discrete-continuous model for calculating the surface binding energy. The best agreement between the calculated and experimental data is obtained with the discrete-continuous model, which yields $\left\langle {{{C}_{{{\text{Ga}}}}}} \right\rangle$ = 30 at % and Y = 2.57, as well as the physically adequate values of the surface binding energy, by varying two fitting parameters. The efficiency of the discrete-continuous model is due to the fact that it takes into account the weak chemical interaction of sample atoms and the ion beam atoms  and the formation of implanted gallium precipitates in irradiated silicon carbide.