On Relationships between Plasma Chemistry and Surface Reaction Kinetics Providing the Etching of Silicon in CF4, CHF3, and C4F8 Gases Mixed with Oxygen

In this work, we discuss the effects of component ratios on plasma characteristics, chemistry of active species, and silicon etching kinetics in CF4 + O-2, CHF3 + O-2, and C4F8 + O-2 gas mixtures. It was shown that the addition of O-2 changes electrons- and ions-related plasma parameters rapidly suppresses densities of CFx radicals and influences F atoms kinetics through their formation rate and/or loss frequency. The dominant Si etching mechanism in all three cases is the chemical interaction with F atoms featured by the nonconstant reaction probability. The latter reflects both the remaining amount of fluorocarbon polymer and oxidation of silicon surface.

Automated summary

In this study, we investigated the impact of component ratios on various aspects of plasma characteristics, chemistry of active species, and silicon etching kinetics in CF4 + O-2, CHF3 + O-2, and C4F8 + O-2 gas mixtures. The results showed that the addition of O-2 significantly altered the plasma parameters, suppressed the densities of CFx radicals, and influenced the kinetics of F atoms. Furthermore, the dominant Si etching mechanism was found to be the chemical interaction with F atoms, which is characterized by a nonconstant reaction probability reflecting the presence of fluorocarbon polymer and oxidation of the silicon surface.