저밀도 플라즈마 측정을 위한 튜닝가능한 랑뮤어 프로브

Abstract

An improved external filter for RF compensation were studied in an inductively coupled plasma. It is difficult to measure the electron energy probability function (EEPF) with the Langmuir probe at low density plasma especially in molecular gas plasma due to RF fluctuation. In contrast with an internal filter, the external filter could be tuned resonance frequency of the choke filter. In previous studies, the external filter has low impedance due to a high value of the stray capacitance between a probe tip and the external filter. To reduce the effect of the stray capacitance, an inductor was connected after the probe tip, and the filter was designed to tune the first and the second harmonic frequency independently. At low density plasma with various gases, the EEPFs are measured to demonstrate the filter performance. The results show the improved performance of the filter as compared to the previous study.