Formation of SiO2 surface textures via CHF3/Ar plasma etching process of poly methyl methacrylate self-formed masks

This work presents a simplified technique for nanotexturing SiO2 surfaces. Nanotextures were obtained by a mask-less dry-etching process of a spin-coated polymethylmethacrylate (PMMA) on a SiO2 surface. Dot-like nanostructures containing small Al particles were initially formed through reactive ion etching (RIE) using CHF3/Ar etchants for an etching duration of 60 s. The etching duration was increased to 2 min to obtain high-density ring-shaped nanomasks with an outer diameter of 80 nm and a wall thickness of 20 nm. The SiO2 surface was textured with ring-shaped nanomasks after 6 min of RIE. The optical reflectance of the nanotextured SiO2 surface after 6 min of etching was around 15% within the spectral interval of 400-1000 nm, which is suitable for optical devices such as solar cells.