Self-consistent particle modeling of inductively coupled CF/sub 4/ discharges and radical flow

The structures of axisymmetrical inductively coupled CF₄ plasmas were examined by the use of the particle-in-cell/Monte Carlo method. The effects of gas pressure and power deposition on the structure of plasmas were examined for 2-10 mtorr and 200-600 W. The electron density increased with the power and pressure, while the electron temperature increased with power deposition and decreased with increasing pressure. The latter resulted in an increase in plasma potential. The density of CF₃ ⁺ ion, which is the dominant positive species, slightly changed with gas pressure. The density of other positive species also weakly depended on the gas pressure and power. The dominant negative ion was F^-. Its density was about half of the electron density. The electron energy distribution was near the Maxwellian distribution. Flows of CF₄ and other CF_x radicals were examined by the use of the direct simulation Monte Carlo method. The production rate of CF_x radicals, which was derived from the plasma simulation, was employed as the input data in the flow simulation. The spatial distributions of pressure, density, temperature, and flow velocity were obtained. CF₄ density increased with pressure and decreased with increasing power. The densities of other CF_x radicals were almost one order smaller than the density of CF₄ and weakly depended on the pressure and power. At a low gas pressure, however, the density of the radicals became comparable to that of CF₄ density. These results are in a qualitative agreement with previous measurements and the results of the global model