Numerical modeling of silicon etching in CF/sub 4//O/sub 2/ plasma-chemical system

Abstract

In the paper the results of numerical optimization of radial flow plasma-chemical reactor in dependence on binary gas composition CF/sub 4//O/sub 2/ are presented. The mathematical model of nonisothermal reactor process with multicomponent chemical kinetics of 12 reactants such as F, F/sub 2/, CF/sub 2/, CF/sub 3/, CF/sub 4/, C/sub 2/F/sub 6/, O, O/sub 2/, CO, CO/sub 2/, COF, COF/sub 2/ was used for numerical calculations. The effects of CF/sub 2/, CF/sub 3/ adsorption and "competition" of chemisorption of fluorine and oxygen atoms on the etching of silicon film were included in consideration. The results of optimizing computations of silicon etching rate and uniformity index in binary gas mixture CF/sub 4//O/sub 2/ are presented. It was shown that the etching rate dependence on fluorine concentration with different fractions Of O/sub 2/ in CF/sub 4//O/sub 2/ has a hysteresis character.