Process Optimization of Plasma Etching on the Size Reduction of Polystyrene Microspheres

The inductively coupled plasma (ICP) etching technique，along with polystyrene (PS) microspheres as masks for etching technology，has been widely applied in the fabrication of silicon nanoarrays.However，the size reduction process of PS microspheres during etching is often accompanied by surface quality degradation.Additionally，the morphology of PS microspheres is influenced by multiple process parameters，making research challenging.To address these challenges，an orthogonal experimental method was employed to thoroughly investigate the process effects of the ICP process in the size reduction of PS microspheres with a particle size of 10 μm.Results showed that the gas composition had a significant impact on the etching effect，while the RF power exhibited positive correlations with both microsphere size reduction and surface roughness，pressure showed a negative correlation with microsphere surface roughness，and gas flow rate had negligible effects.Based on the above conclusions，the optimal process parameters were ultimately determined as follows:addition of 20%CF4 to O2，RF power 200 W-100 W (inductive power-DC bias power)，pressure 3.0 Pa，and gas flow rate 50 mL/min (O2 ∶CF4 flow ratio of 4 ∶1).Under the optimal process parameters，the surface roughness was minimized without compromising the etching reduction effect of PS microspheres.The highly linearized silicon nanoarrays with smooth outer surfaces were successfully fabricated using this optimized template.