Estimation of dissociation degree of N2 in an inductively coupled plasma by vacuum ultraviolet emission spectroscopy

A simple procedure for estimation of the N-2 dissociation degrees in low-pressure, high-density plasmas is proposed. This procedure is applied to the estimation of the N-2 dissociation in an N-2 inductively coupled plasma and confirmed to give N-2 dissociation degrees similar to those reported previously. The rf power and N-2 pressure dependence of the N-2 dissociation degree is also presented. The contribution of stepwise excitation out of N-2 A(3)Sigma(u)(+) [N-2(A)] metastables to the N-2 second positive emission is found to be negligible from the net excitation rate computed using an assumed cross section of the electron-impact excitation from N-2(A) to the N(2)C(3)Pi(u) state and the N-2(A) number density deduced from a simple kinetic model. The recombination of N atoms on the inner surfaces of the plasma reactor used in this study is discussed briefly. Finally, the advantages of the N-2 dissociation estimation by vacuum ultraviolet optical emission spectroscopy are mentioned. (C) 2002 American Institute of Physics.