Schematic of the HfO
nanostructuring process. (a) Schematic drawing of the starting multilayer structure. (b) Patterning of the photoresist by laser interference lithography. (c) Pattern transfer to the SiO2 layer by CF4 ICP-RIE. (d) Pattern transfer to the ARC by O2 ICP-RIE. (e) Selective ICP-RIE of the HfO2 layer with CF4. (f) Elimination of the ARC with O2 ICP-RIE and final cleaning with HCl/H2O.