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

Abstract

A comparative study of the effect of small (up to 20%) substituting additives F2, H2, and HF on the kinetics and stationary concentrations of neutral particles in 50% CF4 + 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 vari-ation of the CF4/F2 and CF4/H2 ratios leads to opposite, interrelated, and nonadditive changes in the con-centrations of fluorine atoms and fluorocarbon radicals. This provides wide ranges of regulation of the etch-ing rate and polymerization capacity with the minimal disturbance of the parameters of the electronic and ionic components of the plasma. In contrast, the CF4/HF relation has the minimal effect on the rate of sur-face polymerization, but noticeably changes the concentration of fluorine atoms. Thus, there is a selective effect on the rate of the heterogeneous chemical reaction.