Determination of the electron temperature in a planar inductive argon plasma with emission spectroscopy and electrostatic probe

The electron temperature of planar inductive argon plasma was studied as a function of the gas pressure between 3 and 100 mTorr with a spectral line ratio in optical emission spectroscopy (OES) and a single Langmuir probe. The electron energy probability function (EEPF) showed a bi-Maxwellian distribution at lower pressures and a Maxwellian distribution at higher pressures. Using optical and probe techniques, it was found that the electron temperature decreases as the pressure increases. The electron temperature determined by the spectral line ratio in OES using optical cross-sections was substantially smaller compared with the scope measured by a Langmuir probe. A novel technique that suppresses the large difference in the electron temperature by correcting the electron excitation kinetics was initiated. The correction factor α( P ), which depends on the gas pressure, was derived from the balance between the measured light intensity and the degree of excitation by collisions via the EEPF and the electron density value obtained from the probe measurement. Taking into account α( P ), the electron temperature according to the spectral line ratio approaches the effective electron temperature using a single Langmuir probe.