Comparison of the Behaviour of Arsenic During Titanium and Tungsten Disilicide Formation

The direct reaction between W or Ti and silicon, to form tungsten silicide and titanium silicide is studied for both unimplanted and arsenic implanted silicon substrates. For W on implanted substrates, the silicide growth rate decreases drastically, being dependent on the implantation dose and energy. The dopant effect can be explained by the formation of a dopant rich phase at the silicide/silicon interface. For Ti, the dopant effect is much less pronounced, slowing down the rate of formation of the silicon rich phase TiSi2. A clear arsenic pile up at the silicide-silicon interface is not observed. The diffusion barrier is distributed in the whole silicide layer.