Abstract: With the continuous reduction of the feature size of integrated circuits, traditional etching techniques are facing challenges in terms of selectivity and physical damage control. Radical etching technology, with its advantages of high precision and low etching damage, has significant application value and broad prospects in micro-nano processing. In this study, radical etching technology was utilized, with CF₄/O₂/He mixed gas as the discharge gas. The influence of discharge parameters, including input power and gas flow rate, on the etching rate of poly-Si and F atomic density has been carefully investigated. The F atomic density during the etching process was quantitatively determined using Ar as an actinometer. The results indicated that both the F atomic density and the etching rate initially increased and then tended to stabilize with the increase of input power or CF₄ flux; appropriately increasing the proportion of He or O₂ could enhance the etching rate, but excessively high He or O₂ flux would lead to a decrease in F atomic density and etching rate. This study displays key parameters in the radical etching process, providing theoretical guidance for optimizing the etching process.