Influencing the hysteresis during reactive magnetron sputtering by gas separation

To circumvent the problem of hysteresis a special design magnetron was developed. The difference with a conventional circular planar magnetron is the central gas pipe which allows introduction and distribution of the inert gas at the target level. In contrast, the reactive gas is introduced globally in the vacuum chamber. The effect of the gas separation was investigated using three different target materials (Mg, Al, and Ti), and by comparing the obtained process curves with the normal setup where both the reactive and the inert gas are introduced together in the vacuum chamber. For Al the difference between both ways of introducing the reactive gas is most clear. For Ti and Mg the effect is negligible but for two different reasons. In the case of Ti, the hysteresis under normal conditions is already quite weak, and therefore changing the setup has a minor influence. Magnesium is very sensitive for even traces of oxygen, and the hysteresis is quite pronounced. Therefore it is difficult to change. In the latter case, a series of experiments were performed at extreme high flows, showing that even for systems with a pronounced hysteresis, it is possible to influence the hysteresis.