窒素イオン注入によるＺｒＮ層の形成と熱処理効果

Abstract

To study the formation process and thermal stability of ZrN layers under nitrogen ion implantation, zirconium films have been implanted with 15N2 ions of 100keV at doses of from 1×1017 to 10×1017N/cm2, at room temperature and 500°C. Effects of post-implantation annealing were also investigated. The depth distribution of the implanted nitrogen was measured in detail by nuclear reaction analysis using the 15N (p, α γ)12C reaction at Ep=429keV. The structure of the implanted layers was measured by thin film XRD, and hardness was measured by a Knoop microhardness indenter. It was found that nitrogen concentration exceeded 50% in the layers that were just shallower and deeper than the mean projected range of nitrogen for a dose of 7×1017N/cm2. The overstoichiometric layers were eliminated by the subsequent ion implantation and a trapezoidal distribution was obtained at a dose of 10×1017N/cm2. The distribution of nitrogen implanted at 500°C can be explained by thermal diffusion, precipitation of nitrogen in the surface layer, and sputtering by ion bombardment. The structure of the ZrN layer produced by nitrogen implantation at room temperature was improved by 500°C annealing, but thermal diffusion of the implanted nitrogen became obvious at 700°C annealing.