Discharge profiles of internal-antenna-driven inductively-coupled plasmas

In this work radio frequency inductively-coupled plasmas (ICPs) sustained with a single low-inductance antenna (LIA) have been characterized in an attempt to clarify profiles of plasma parameters in the near-antenna region. The present investigations have been carried out for the purpose of understanding the local discharge features with a single LIA unit, which are regarded as one of the elements for sustaining large-area plasma source with multiple LIA configurations. The ion-saturation current profiles had a peak at a distance of 10–20 mm from the outer surface of the antenna insulator and then decreased with increasing distance from the antenna, while the electron temperature peaked in the vicinity of the outer surface of the antenna insulator. These results suggest that the discharge sustained with a single LIA is mainly excited via the induction electric field, which is inherent in near-field nature of the induction electric fields peaking in the vicinity of the antenna and attenuating with a depth of penetration (skin depth) in the plasma. Distribution of the RF fluctuation of the floating potential was also measured to evaluate the electrostatic coupling of the antenna to the plasma.