Fig. 1. Diagram of the fitted removal function

Fig. 2. Diagram of the raster path scan

Fig. 3. Simulation of different stacking spacings. (a) Stacking spacing is σ; (b) stacking spacing is 1.5σ; (c) stacking spacing is 2σ

Fig. 4. Fluctuation value curve

Fig. 5. One-dimensional equivalent-etching results of ion beams with different stacking spacings. (a) Stacking spacing is σ; (b) stacking spacing is 1.2σ; (c) stacking spacing is 1.5σ

Fig. 6. One-dimensional equivalent removal contour of ion beams with different stacking spacings. (a) Stacking spacing is σ; (b) stacking spacing is 1.2σ; (c) stacking spacing is 1.5σ

Fig. 7. Simulation of two-dimensional equivalent removal. (a) Top view; (b) side view

Fig. 8. Two-dimensional equivalent removal results. (a) Etching result; (b) etching profile

Fig. 9. Surface shape before ion beam modification

Fig. 10. Dwell time distribution map

Fig. 11. Dwell time distribution map after continuation

Fig. 12. Simulated processing result

Fig. 13. Full-caliber surface shape after ion beam modification

Fig. 14. Surface shape of 85% aperture after ion beam modification