The particle bombardment and other effects occurring in plasma systems used to process semiconductor devices have been described and characterized, in particular in the dc and RF diode and dc triode systems commonly used for processing. DC diode systems and RF diode systems are shown to cause degradaztion in processed devices due to energetic particle bombardment, as do de triode systems. In triode systems magnetic field protection is of assistance; in dc and RF diodes, grid systems may be necessary. Since the degradation of processed devices is often not annealable, some protection of devices from degradation during processing may be essential.