On the Effect of the Ratio of Concentrations of Fluorocarbon Components in a CF4 + C4F8 + Ar Mixture on the Parameters of Plasma and SiO2/Si Etching Selectivity

The effect of the CF4/C4F8 ratio in a CF4 + C4F8 + Ar mixture on the parameters of the gaseous phase of a low-pressure inductively coupled plasma, defining the kinetics and selectivity of etching in an SiO2/Si system, is investigated. It is found that increasing the SiO2/Si etching ratio, with an increase of the quantity of C4F8 in the plasma-forming mixture, is determined by various changes of the effective interaction probabilities for these materials. It is demonstrated that, within the investigated range of conditions, the kinetics of the formation of the fluorocarbon polymer film on the processed surface exerts a decisive influence on the character of the variation of the effective interaction probability. The interrelationships between the gas-phase and heterogeneous characteristics of the etching process are revealed.