Pressure dependence of the nitrogen dissociation fraction and concentration of active species in Magnetic Pole Enhanced Inductively Coupled Plasma

摘要

RF generated inductively coupled Ar-N_2 plasma is investigated by optical emission spectroscopy and Langmuir probe over a wide range of filling pressure (15-300mTorr), different rf power (10-100W) and various argon content (5-95%) in nitrogen discharge. The emission intensity of second positive band head of molecular nitrogen N_2 at (λ=337.1 nm, 0-0) and atomic nitrogen N at (λ=746.83 nm) are used to determine the concentration of their ground electronic states and dissociation fraction using actinometry method. The Boltzmann plot method is used to calculate the excitation temperature. Important plasma parameters such as electron temperature and electron number density are determined by the Langmuir probe for different discharge conditions in Ar-N_2 discharge. It is observed that the filling pressure and input rf power influence strongly the plasma parameters, dissociation fraction and the concentration of reactive species in the ground electronic state. "The maximum dissociation is found with filling pressure of 150mTorr in Ar-N_2 plasma". It is also found that the excitation temperature and electron temperature have similar trends with rf power and filling pressure.PACS: 52.80.Hc; 52.80.Sm; 34.70. +e; 52.70.Kz; 81.65.Lp)