Fig. 1. (a)–(d) Schematic illustrations of the mask fabrication process by the Au electroplating process, SEM images of the 2D hole mask with (e) 280 nm pitch and (f) an area of 600μm×600μm. Scale bars for (e) and (f) correspond to 500 nm and 200 μm.

Fig. 2. SEM images of the fabricated square nanopatterns with 198 nm period at (a) 0.48 mm and (b) 1.5 mm with a dose of 900mJ/cm2. Scale bars for (a) and (b) are equal to 200 nm. SEM images of the fabricated square nanopatterns with 424 nm period at (c) 2.24 mm and (d) 4.5 mm with a dose of 450mJ/cm2. Scale bars for (c) and (d) are equal to 500 nm.

Fig. 3. (a) Illustration of the three-dimensional graph of the mask structure. A 60 nm thick Au layer with 50% duty cycle was put on a 100 nm Si3N4 membrane. (b) Illustration of the 2D graph of the mask structure. (c) Illustration of the side view of the mask structures with period P and hole diameter D.

Fig. 4. Calculated images for the mask with 280 nm pitch at (a) 0.488 mm and (b) 1.5 mm. Calculated images for the mask with 600 nm pitch at (e) 2.24 mm and (f) 4.5 mm. (c), (d) and (g), (h) Profiles of electrical field intensity distribution along the white dashed lines in (a), (b) and (e), (f), respectively.

Fig. 5. (a), (b) Two representative monochromatic electrical field intensity distributions for the square lattice mask with 600 nm period at 4.5 mm. (c), (d) The sum of those two group patterns with the same symmetry as that in (a) and (b).