A nanoscale conical polymethyl methacrylate (PMMA) sub-wavelength structure with a high aspect ratio realized by a stamping method.

A high aspect ratio conical sub-wavelength structure (SWS) was designed by using rigorous coupled-wave analysis (RCWA) method and was realized on polymethyl methacrylate (PMMA) film using a stamping technique. The silicon template containing a hexagonal array of conical holes with a period of 350 nm and an aspect ratio of 2.8 was fabricated by electron-beam (e-beam) lithography followed by a two-step etching process. The SWS with a high aspect ratio was easily transferred from the fabricated silicon template to PMMA film using the stamping method. The replicated PMMA SWS has an array of cones with nanoscale tips and an aspect ratio higher than 2.8. The average reflectance and transmittance of the PMMA film with the conical SWS in the wavelength ranging from 500 and 1500 nm was improved from 7.1 and 91.1% to 4.3 and 94.2%, respectively, as compared to flat PMMA film.