Influence of etching process parameters on the antireflection property of Si SWSs by thermally dewetted Ag and Ag/SiO 2 nanopatterns

The etching parameter dependent antireflection characteristics of disordered Si subwavelength structures (SWSs) by inductively coupled plasma (ICP) etching in a mixture gas of SiCl 4 /Ar using thermally dewetted Ag and Ag/SiO 2 nanopatterns are investigated. The average size and period of Si SWSs are closely correlated with thermal dewetting conditions. For desirable Ag nanoparticle patterns, the profile of Si SWSs is optimized by changing the ICP etching process parameters to obtain the lowest reflectance spectrum. The most tapered SWS with the highest height leads to a relatively low reflectance. The Ag nanopatterns result in more tapered and rough surface SWSs compared to the Ag/SiO 2 nanopatterns, indicating a slightly reduced reflectance. The Si SWS etched using Ag nanopatterns by SiCl 4 /Ar of 5 sccm/10 sccm at 50 W RF power, 200 W ICP power, and 10 mTorr process pressure exhibits a very low total reflectance of <∼2.4% in the wavelength range of 400–1000 nm, maintaining a specular reflectance of <16% at 350–1100 nm up to the incident angle of θ i  = 50°.