TRANSITION FROM A CAPACITIVE TO A RESISTIVE REGIME IN A SILANE RADIO-FREQUENCY DISCHARGE AND ITS POSSIBLE RELATION TO POWDER FORMATION

Self-consistent fluid and particle-in-cell models of radiofrequency glow discharges have been used to analyze the existence of different regimes experimentally observed in silane discharges. The discharge ionization mechanism changes from a situation where the ionization occurs during the expansion of the sheath to a situation where the bulk plasma plays a major role. We suggest that the transition is consistent with powder formation with increasing power. This leads to supplementary losses of electrons and then to an increase in the plasma electric field.