PLASMA PARAMETERS AND KINETICS OF ACTIVE SPECIES IN HBr + Cl2 + O2 GAS MIXTURE

Abstract

In this work, we performed the combined (experimental and model-based) study of gas-phase plasma characteristics for HBr + Cl2 + O2 gas mixture under conditions of low-pressure inductive 13.56 MHz discharge. The data on internal plasma parameters, plasma chemistry as well as the steady-state plasma composition were obtained using a combination of Langmuir probe diagnostics and 0-dimensional (global) plasma modeling. Both experimental and modeling procedures were carried out at constant total gas pressure (p = 10 mTorr), input power (W = 500 W), bias power (Wdc = 200 W) and O2 fraction in a feed gas (y(O2) = 11 %). The variable parameter was the HBr + Cl2 mixing ratio, which was changed in the range of 0 – 89 % Cl2. It was found that, under the given set of experimental conditions, the substitution of HBr for Cl2: 1) results in increasing both mean electron energy and electron density; 2) causes the mon-monotonic (with a maximum at ~ 45 % Cl2) change in Br atom density; and 3) provides an increase in O atom density at y(O2) = const. The possible impacts of HBr + Cl2 mixing ratio on Si and SiO2 etching kinetics were estimated through the analysis of model-predicted fluxes for plasma active species (Br, Cl and O atoms, positive ions).