Determination of Electron Temperatures in Rare-Gases Plasma


Trace rare gases optical emission spectroscopy has been used to measure the electron temperature (Te) in a high-density inductively coupled dichloride-argon (Cl2-Ar) plasma at 0.018Torr as function of the radio-frequency power of 13.56MHz frequency and argon (Ar) fraction. Only the krypton (Kr) and xenon (Xe) emission lines were used to determine electron temperature (Te) because of evidence of radiation trapping, when the argon emission lines were also used for larger Ar fractions. At 600W, electron temperature (Te) increases from 4.06±0.5eV to 6.06±2.0eV as the Ar fraction increases from 1% to 96%. In the inductive mode, electron temperature (Te) for chlorine plasma, including 1% of each He, Ne, Ar, Kr and Xe, increases only slightly from 3.8eV to 4.0eV as power increases from 450W to 750W. This increase is much larger for larger Ar fractions, such as from 4.0eV to 7.3eV for 78% Ar. Most of these effects can be understood using the fundamental particle balance equation.