Control and analysis of ion species in N2 inductively coupled plasma with inert gas mixing

We control the ion density ratio of [N+]/[N-2(+)] and investigate the relation between the ion ratio and the plasma parameters in inductively coupled plasma. We measure the electron energy distribution functions and the ion ratio in a N-2/He,Ar,Xe mixture system as a function of mixing ratio. We can control the ion ratio from 0.002 to 1.4, and the ion ratio is a strong function of electron temperature. We can calculate the ion ratio using a simple model, and the obtained results agree well with the measured values in N-2/He,Ar, but there is a large discrepancy in the N-2/Xe discharge. The non-Maxwellian structure of the electron energy distribution functions may be the reason for the discrepancy. (C) 2002 American Institute of Physics.