Time-resolved optical emission spectroscopy during pulsed dc magnetron sputter deposition of Ti and TiO₂ thin films

Time-resolved optical emission spectroscopy is applied to analyse pulsed dc magnetron plasmas during sputter deposition of Ti and TiO₂ thin films. The studies are focused on the temporal behaviour of emissions of selected atomic titanium, argon and oxygen during the 'on-time', when the magnetron plasma source is turned on, and during the 'reverse-time', when the magnetron plasma source is turned off. Single and double exponential decays of the optical emissions were found during the 'reverse-time'. During the 'on-time', we observed a rapid increase in some emissions with a more or less pronounced overshoot and a slow increase in other emissions which follow the temporal evolution of the conduction current. The various time constants can be related to the dynamics of the fast electrons, the Ar metastables, the Ti atoms (metallic mode) and the O atoms (oxide mode).