Target-Surface Compound Layers Formed by Reactive Sputtering of Si Target in Ar+O2 and Ar+N2 Mixed Gases
Reactive sputtering is a very useful and widely used technique for preparing compound thin films, however, the target surface state is not fully understood. In this study, a Si wafer was used as a model sputtering target, and the thickness of the oxide and nitride layers formed on the target surface after sputtering in Ar+O2 and Ar+N2 mixed gases, respectively, was measured by ellipsometry. The maximum thicknesses of oxide and nitride layers were found to be approximately 7 nm in pure O2 gas and 4 nm in pure N2 gas, respectively. The oxidation rate of Si in oxygen plasma was thought to be higher than the nitridation rate of Si in nitrogen plasma.