Correlation between vibrational temperature of N-2 and plasma parameters in inductively coupled Ar/N-2 plasmas

Abstract

Vibrational temperature (T-vib) of N-2 gas and electron energy distribution function (EEDF) were measured in Ar/N-2 mixture inductively coupled plasma (ICP). At a low gas pressure of 5 mTorr where the EEDF is bi-Maxwellian distribution, plasma density n(p) and T-vib (from 7000K to 5600 K) slightly decrease. However, remarkable decrease in n(p) and T-vib is found with the dilution of N-2 gas at a high gas pressure of 50 mTorr, where the EEDF is depleted Maxwellian distribution at a fixed ICP power of 150 W. When the ICP power increases from 150 W to 300 W at the gas pressure of 50 mTorr, the depleted tail on the EEDF is replenished, while n(p) is little changed with the dilution of N-2 gas. In this case, T-vib slightly decreases from 9500 K to 7600 K. These results indicate that the variation of T-vib is strongly correlated to the plasma parameters, such as the plasma density and EEDF.