Study of silicon dioxide focused ion beam sputtering using electron microscopy imaging and level set simulation

Sputtering silicon dioxide by the ion beam of gallium ions was studied to obtain the angular dependence of the sputtering yield and estimate the secondary sputtering yield of the redeposited material. For this purpose, rectangular boxes were formed in the SiO 2 layer at different incidence angles of the ion beam. The box depths and the distributions of gallium atoms were estimated using the cross-sectional specimens examined by scanning and transmission electron microscopy techniques. The found depth values enabled calculating the sputtering yield angular dependence which was approximated using well-known fitting formulas. It was also demonstrated that for an incidence angle varied from approximately 40°–70° ripple topography is formed on the ion bombarded silicon dioxide. To validate the obtained data characterizing SiO 2 sputtering, test symmetrical and asymmetric structures with different aspect ratios were experimentally prepared and simulated using the level set method taking into account the redeposition effect and reflection of incident ions from the sputtered surface. It was established that the performed simulation provides sufficient accuracy in predicting the shape of the focused ion beam fabricated structures in silicon dioxide. • The ion-irradiated areas were imaged using scanning and transmission electron microscopy. • The angular dependence of the SiO 2 sputtering yield was experimentally determined. • The distribution of the gallium atoms in the near-surface region was evaluated. • The secondary sputtering yield of the redeposited material was established. • The nanostructure fabrication process was simulated using the level set method.