Global model of plasma chemistry in a low-pressure O2/F2 discharge

Global model (volume averaged) calculations are used to study the plasma chemistry in an O-2/F-2 low-pressure high-density discharge. The plasma parameters. electron temperature T-e, dc plasma potential V-pl, electronegativity n(-)/n(e) as well as the densities of the species, were calculated as a function of F-2 content and discharge pressure in the pressure range 1-100 mTorr. The fluorine discharge is highly dissociated. The density of the fluorine atom increases as F-2 is added to the discharge and for mixtures with similar to35% F-2 atomic fluorine is the dominating specie in the discharge. At a fixed ratio of O-2 to F-2, <50% F-2 in the flow rate, the electron temperature decreases with increased pressure and the dominant positive ion species changes from being O+ at low pressure (<5 mTorr) to O-2(+) at high pressure (>50 mTorr). At a fixed ratio of O-2 to F-2, >50% F-2 in the flow rate, the electron temperature decreases with increased pressure at low pressure (<5 mTorr). increases with further increase in pressure up to roughly 40 mTorr and decreases again with further increase in pressure. The dominant positive ions change from being O+ and F+ at low Pressure (<5 mTorr) to O-2(+) and F-2(+) at high pressure (>50 mTorr).