FREQUENCY-EFFECTS IN CAPACITIVELY COUPLED RADIOFREQUENCY GLOW-DISCHARGES - A COMPARISON BETWEEN A 2-D FLUID MODEL AND EXPERIMENTS

The results of a 2-D fluid model for argon radiofrequency (RF) discharges in a closed cylindrical vacuum chamber are compared with experimental data from an amorphous silicon deposition reactor operated in argon. Good agreement is obtained for the relation between the DC autobias voltage and the dissipated power in the frequency range 40-100 MHz at pressures between 10 and 60 Pa. Scaling laws are presented for the dissipated power and for the ion fluxes toward the electrodes. These quantities are expressed in the DC bias voltage, the RF excitation frequency and the background pressure, Also the uniformity of the ion fluxes is studied. The model yields a linear relation between the applied RF voltage and the DC bias voltage. This relation depends only on the geometry of the discharge chamber and shows an offset.