Antireflective silicon subwavelength structure formed by self-aggregated gold nano particle as a catalyst

초록

A Subwavelength structure (SWS) was formed by simple chemical wet etching using two types of gold (Au) catalysis to compare the etching speed due to difference of fill factor. One is the Au thin film which has almost 100 % fill factor and the other is the Au nano particle which has about 50 % fill factor. Single nano-sized Au particle was fabricated by metal self-aggregation effect. The deposition and the thermal annealing of the metallic thin film were carried out. The thermal annealing of a metallic thin film enables to create metal nano particles by isolate from each other by means of the self-aggregation of the metal. Then, samples were soaked in an aqueous etching solution of hydrofluoric acid and hydrogen peroxide. When Si etched during 20 minutes using the Au thin film, the reflectance decreased about 8 %. But, when Si etched just 3 minutes using the Au nano particle, the reflectance decreased below 3 %, and added 10 minutes etch, the reflectance decreased almost 0 % in the whole range from 300 to 900 nm owing to deep and steep double tapered structure.