The influence of the oxygen partial pressure on the ion nitriding of aluminium - An investigation by means of real time elastic recoil detection analysis

Aluminium is known to be a difficult candidate for successful nitriding. It exhibits a dense native surface oxide layer that acts as a barrier for dif fusional nitrogen transport. To investigate the influence of the oxygen par tial pressure, samples of pure polycrystalline Al were ion nitrided at diff erent oxygen partial pressures from a hot filament ion source. Before and d uring the nitriding process depth profiling of nitrogen and oxygen has been performed by real time elastic recoil detection analysis. The oxygen parti al pressure plays a crucial role for the evolution of the surface oxide lay er and thus for the nitriding result. If the surface oxide layer is removed an AlN-layer grows. The evolution of the oxide layer is compared to semi-q uantitative considerations on the interplay of sputtering and oxidation. A criteria for the removal of the surface oxide layer is given. (C) 2000 Publ ished by Elsevier Science B.V. Ah rights reserved.