Generation of Positive and Negative Oxygen Ions in Magnetron Discharge During Reactive Sputtering of Alumina

The paper is devoted to the investigation of ion composition of plasma of dc pulsed magnetron discharge generated by a magnetron with Al target in an Ar/O-2 mixture. The magnetron discharge was investigated in the non-reactive, metallic and oxide mode of sputtering using a mass spectrometer. The amount and energies of neutral oxygen atoms O, positive O+ and O-2(+) ions, and negative O- and O-2(-) ions were measured as a function of oxygen flow rate phi(O2), magnetron voltage U-d and constant power P-d = 400 W delivered to the magnetron discharge, repetition frequency of pulses f(r) = 10 kHz and the ratio of O-2 and Ar flow rates phi(O2)/phi(Ar). The content of ions and radicals in magnetron discharge is compared with optical spectroscopy measurements. The obtained results give a deeper insight into reactive magnetron sputtering of oxide films.