Figure 3.

SEM images of (a) a single layer of microspheres (0.97 μm diameter) on top of photoresist; (b) AZ5214 photoresist nanoholes after microsphere removal and photoresist development; (c) high aspect-ratio cross-section of nanopatterns formed by silica spheres and AZ5214 photoresist; (d) Shipley 1805 photoresist used as negative photoresist to form nanopillars of photoresist

Wu et al. Nanoscale Research Letters 2008 3:123-127   doi:10.1007/s11671-008-9124-6