SEM images of polystyrene honeycomb mask and photoresist honeycomb mask. (a, b) Polystyrene honeycomb mask after removing silica spheres by immersion in 10 wt.% HF for 10 min and (c, d) photoresist honeycomb mask formed by sphere lithography. (a, c) Low-magnification and (b, d) high-magnification images taken at an angle of 45° to the surface.
Asoh et al. Nanoscale Research Letters 2012 7:406 doi:10.1186/1556-276X-7-406