Fabrication of Anti-Reflective Composite Structures on Inverted Pyramids Using Inductively Coupled Plasma Etching

The anti-reflective properties of silicon surfaces play a pivotal role in determining the light absorption efficiency of various silicon-based optoelectronic devices, with surface micro-nanostructures emerging as a crucial technological approach for achieving enhanced anti-reflection. In this study, inverted pyramid structures were employed as the micron-scale framework, and micro-nano composite structures were successfully prepared using an inductively coupled plasma (ICP) etching system. This paper, mainly focused on the micro-nano fabrication, investigated the effects of gas flow rate ratio (SF₆:O₂:C₄F₈), ICP power, RF power, and etching time on the surface morphology and reflectance of the composite structures. The results demonstrate that the optimal anti-reflective micro-nano composite structure was achieved under the following conditions: SF₆ flow rate of 18 sccm, O₂ flow rate of 9 sccm, C₄F₈ flow rate of 4 sccm, ICP power of 300 W, RF power of 5 W, and etching time of 5 min. The average reflectivity of the prepared surface structure was as low as 1.86%.