Characterization of a low-frequency inductively coupled plasma source

A hemispherical inductively coupled plasma source is characterized with Langmuir probes, microwave interferometry, voltage, and current monitors, optical emission, and mass spectrometry. The plasma source is operated with up to 2 kW of 0.46 MHz rf power and with a 5 mTorr mixture of argon, oxygen, and hydrogen gases. The rf power is efficiently coupled to the plasma. The ion and neutral compositions show substantial dissociation and water vapor formation. Maps of ion density, electron temperature, and plasma potential are obtained that are consistent with diffusive particle transport and edge power deposition. The latter contributes to an excellent plasma radial uniformity near the bottom electrode. (C) 1996 American Vacuum Society.