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) dischar ges in a closed cylindrical vacuum chamber are compared with experimen tal data from an amorphous silicon deposition reactor operated in argo n. 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 di ssipated power and for the ion fluxes toward the electrodes. These qua ntities are expressed in the DC bias voltage, the RF excitation freque ncy 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 ge ometry of the discharge chamber and shows an offset.