Abstract
Measurements of mass loss during sputtering, atomic emission intensities, and ionization characteristics are described for a coaxial magnetron glow-discharge device. By the use of the magnetic field from a coaxial magnet pair placed behind the cathode, stable plasma operation is achieved for all pressures from 0.0004 Torr (0.05 Pa) to over 2.5 Torr (330 Pa). Mass loss measurement values from pellets of Al, Cu, brass, Zn, and Au located in the region of greatest sputtering show much larger values at pressures which are lower than those usually used with glow-discharge excitation and ionization sources. Emission line ratio measurements at the lower pressures indicate that populations of low-energy electronic states are greater than equilibrium values. This observation suggests that the plasma is dominated by ionization processes rather than by recombination processes. Emission line ratio and mass spectrometric measurements also indicate that ionization is increased at the lower pressures.
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