The Correlation between an Electric Field and the Metastable Chlorine Ion Density Distributions in an Ultrahigh-Frequency Plasma

Abstract

The electric field strength in an ultrahigh-frequency (UHF) plasma, as well as in an inductively coupled plasma (ICP), is measured with an electrostatic probe as a function of the radial and azimuthal positions of the plasma reactor. On comparing the electric field distribution with the radial density profile of metastable chlorine ions measured by Doppler-shifted laser-induced fluorescence, the electric field distribution is determined to be positively correlated to the ionization rate distribution in the UHF plasma, while that in the ICP seems to be less dependent on the electric field distribution. This phenomenon probably arises due to the large difference in the discharge frequency between the UHF plasma and the ICP. No remarkable azimuthal dependence of the radial average velocity and the temperature of the metastable Cl+ is observed, indicating that the two-dimensionally uniform plasma is produced by UHF power through a spokewise antenna.