CONSIDERATION OF THE CHEMICAL-REACTIVITY OF TRACE IMPURITIES PRESENT IN A GLOW-DISCHARGE

Optical and mass spectrometric diagnostics were applied in a study of the chemical reactivity of the plasma impurity species in an r.f. glow discharge source. Copper, Fe and Ta metals and Ta powder-based compac ted discs were chosen as test cathodes. A cryogenic coil incorporated within the discharge source was used in the investigations of the pote ntial interactions. Significant increases were observed in the sputter ing gas and cathode matrix ion signals, as well as the ground- and exc ited-state populations of these species with cryogenic cooling. The re lative reactivities of the matrix-element species with water-related s pecies in the plasma and the significance for glow discharge-based ana lytical techniques are discussed