A global model for BF3 plasma in a RF-driven multicusp ion source

A volume averaged model for BF₃ discharges in a RF-driven, inductively coupled multicusp ion source, such as that used on the ULE2 ion implanter, has been developed. Particle and energy balance equations are solved to determine the electron temperature and the densities of all molecular, atomic, and ionic species of interest, including some multiply charged species, as functions of input power, gas flow rate, and source geometry. Comparison of model predictions with extracted beam species distributions is made over the full range of operating conditions of the ULE2 source. Surface magnetic confinement and wall chemistry effects are taken into account using simple models. Extension of the model to other species of interest including PH₃ , AsH₃, and O₂ is discussed