Prediction of nanopattern topography using two-dimensional focused ion beam milling with beam irradiation intervals

Beam irradiation intervals are a critical parameter in the fabrication of nanopatterns via focused ion beam (FIB) milling. The beam irradiation intervals are defined in terms of the overlap. In this paper, the nanopattern height on a silicon surface is predicted using a mathematical FIB milling model that varies the overlap. The proposed model takes into account the angle dependence of the sputtering yield and redeposition effect, together with the superposition of a bi-Gaussian beam. The model was verified by comparing the results of a nanopattern machining experiment to those of a simulation based on the model. The simulation calculated the final two-dimensional geometry from ion milling parameters. The results of the simulation indicate that the proposed model is more precise than one that only considers the superposition of a Gaussian beam.