Oxygen active species in an Ar–O2 magnetron discharge for titanium oxide deposition

Emission spectroscopy of an Ar–O2 dc magnetron sputtering plasma has been performed at 3.5 cm above a Ti target. The behavior of O2+ and O have been studied by introducing O2 into the Ar plasma. The vibrational distributions of O2+ (b) radiative state have been determined. It is found to exhibit a quasi-Boltzmann distribution with vibrational temperatures between 2500 and 3500 K for discharge current between 200 and 500 mA at 5 mTorr. By comparing intensities of O and O2+ by emission spectroscopy and O2+ relative density by mass spectroscopy, the O/O2 relative dissociation rate is found to be followed by the IO/IO2+ optical intensity ratio. It is found to have an increase of nO/nO2 with the discharge current.