A comparative study of CF4/O2/Ar and C4F8/O2/Ar plasmas for dry etching applications

The effect of the O-2/Ar mixing ratio in CF4/O-2/Ar and C4F8/O-2/Ar inductively coupled plasmas with a 50% fluorocarbon gas content on plasma parameters and active species densities, which influence dry etching mechanisms, was analyzed. The investigation combined plasma diagnostics using Langmuir probes and zero-dimensional plasma modeling. It was found that, in both gas systems, the substitution of Ar for O-2 results in a similar change in the ion energy flux but causes the opposite behavior for the F atom flux. The mechanisms of these phenomena are discussed with regards to plasma chemistry. (C) 2015 Elsevier B.V. All rights reserved.