Comparative study of CF4- and CHF3-based plasmas for dry etching applications

The influence of O 2 /Ar mixing ratio on plasma characteristics, densities and fluxes of active species determining the dry etching kinetics in both CF 4 /O 2 /Ar and CHF3/O2/Ar plasmas was studied. The investigation combined plasma diagnostics by Langmuir probes and zero-dimensional plasma modeling. It was found that the substitution of O 2 for Ar at constant fraction of CF 4 or CHF 3 in a feed gas noticeably changes electron temperature and electron density, but does not result in the non-monotonic behavior of F atom density. The differences between two gas systems were discussed in details from the point of view of plasma chemistry.