MODELING AND EXPERIMENTAL STUDIES OF A REACTIVE ION ETCHER USING SF6/O2 CHEMISTRY

A mathematical model of a showerhead-type reactive ion etching reactor using SF6/O2 chemistry is developed. Experimental measurements of the plasma density, electron energy, and exit gas composition are used to provide information on the gas-phase reactions taking place and the values for the kinetic rate constants. The concentration distributions of the various molecules and radicals are obtained by solving numerically the mass balances with finite differences. Surface recombination and competition between flourine and oxygen atoms to absorb on the silicon surface are considered, and the chemical etch rate of silicon is calculated. A correlation between the activation energy of the etching reaction and the energy and density of bombarding ions is obtained by comparing the calculated chemical etch rate distribution with the one measured experimentally.