Fig. 1. Schematic diagram of measurement system

Fig. 2. Diagrams of simulated sample. (a) 3D structure of the simulated sample; (b) cross section of 200th row

Fig. 3. Results of simulation. (a) The restored results; (b) the error distribution; (c) the 200th row cross section of each restored result

Fig. 4. Configuration of experimental system

Fig. 5. Standard step sample surface height measurement results

Fig. 6. Comparison between practical modulation curves and theoretical modulation curves. (a) Comparison of 20 nm step group; (b) comparison of 30 nm step group; (c) comparison of 40 nm step group; (d) comparison of 50 nm step group

Fig. 7. Experimental results. (a) 3D restoration result of 20 nm step group; (b) 3D restoration result of 30 nm step group; (c) 3D restoration result of 40 nm step group; (d) 3D restoration result of 50 nm step group