Saturated thickness of nitride layers formed by high fluence nitrogen implantation into metals

The thickness of the nitride layer formed by a high fluence nitrogen implantation to a metal surface is limited mainly because of the sputtering effects and the migration of the implanted nitrogen towards the surface. We have investigated nitrogen depth profiles implanted to several kinds of metals theoretically by Monte Carlo simulation using the dynamic-SASAMAL code and experimentally by RES and NRA using the N-15(p,alpha gamma)C-12 reaction. In this paper, the saturation fluence and the saturated nitride thickness were calculated for 1-200 keV nitrogen implantations into several kinds of metals (Al, Ti, Fe, Zr, and Hf). In order to find the method to overcome the limited thickness and the severe radiation damage problem at the high fluence implantations necessary for the saturation, the nitrogen depth profiles for an energy scanning implantation with a uniform and a non-uniform energy distribution was calculated and compared with those of mono-energetic implantations.