The Influence of Small F2, H2, and HF Additives on the Concentration of Active Particles in Tetrafluoromethane Plasma

A comparative study of the effect of small (up to 20%) substituting additives F 2 , H 2 , and HF on the kinetics and stationary concentrations of neutral particles in 50% CF 4 + 50% Ar plasma under the typical conditions of reactive ion etching (RIE) of silicon and its compounds is carried out. It is shown that the variation of the CF 4 /F 2 and CF 4 /H 2 ratios leads to opposite, interrelated, and nonadditive changes in the concentrations of fluorine atoms and fluorocarbon radicals. This provides wide ranges of regulation of the etching rate and polymerization capacity with the minimal disturbance of the parameters of the electronic and ionic components of the plasma. In contrast, the CF 4 /HF relation has the minimal effect on the rate of surface polymerization, but noticeably changes the concentration of fluorine atoms. Thus, there is a selective effect on the rate of the heterogeneous chemical reaction.