Target surface oxide layer formed by reactive sputtering of Ti target in $Ar+O2$ mixed gas

Reactive sputtering is one of the most widely used techniques for preparing compound thin films. In this study, a Ti model target, a $1μm$ thick Ti film sputter deposited on a Si wafer, was used as the sputtering target. The thickness of the oxide layer formed on the surface of the model target after sputtering in an $Ar+O2$ mixed gas atmosphere was measured by ellipsometry under various varying processing parameters including oxygen flow ratio, sputtering time, rf power, and total gas pressure. The oxide layer thickness was varied from a few nanometers to approximately $100nm$ by changing the parameters, and a nonuniform oxide layer thickness was observed on the target surface.