The discharged characteristics of capacitively coupled Ar/N₂ plasma driven by the dual frequency 8/100 MHz

Abstract

The discharged characteristics of capacitively coupled Ar/N2 plasma driven by 8 MHz and 100 MHz are investigated at low pressure. The mean electron temperatures at central plasma area are discussed by the corona model with the high frequency (HF) power increase (low frequency (LF) power is fixed) and argon increase. The second positive system (SPS) of nitrogen molecular (C3Πu→B3Πg) from 370 nm to 410 nm in the N2 optical emission spectrum is used to calculate the rotational and vibrational temperature of nitrogen molecular. These results show that the mean electron temperatures both decrease with the argon increase and the HF power increase. The rotational temperature increase with argon increase and decrease with the HF power increase. The particle-in-cell/Monte Carlo (PIC/MC) method is used to calculate the ion density, electron temperature and electron energy probability function (EEPF) according to experimental conditions. These results show that the electron temperatures both decrease with HF power increase and argon content increase, which are agreed with the spectral results. The EEPF show that the low and high energy electrons both increase with the HF power increase and argon increase. The energy exchange by these higher energy electrons is large, which result in the decrease of electron temperatures.