연도 | 2009 |
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저널명 | Journal of Korean Physical Society |
쪽 |
The particle contamination and the plasma perturbation by the probe invasion
in the plasma, as the electrical Langmuir probes, should be minimized in the
plasma processing. Since the floating probe method can be minimized to the probe
contact to the plasma, it becomes attractive to monitor the plasma properties.
For the floating probe method, the plasma properties are analyzed from the AC
coupled current signals flown in the system of probe circuit. The main current
is consisted of a displacement current through the stray capacitance of probe
system and a conduction current through the probe sheath. Thus the current
signal is sensitive to the capacitance of probe system and the driving
frequency, so the accuracy of measurement can be improved with the minimization
of the displacement component in the current signal. Here it is introduced that
the accuracy of measurement can be achieved from the conduction sheath current
obtained from the extrapolation of the harmonics of current signals which are
taken at the several different bias frequencies. In addition, the driving
frequency of probe can be optimized with the consideration of the sensing
resistance, the sheath resistance, and the stray capacitance. The improvement of
accuracy in the plasma density and temperature measurements was demonstrated for
the various operating pressures and powers.