Reverse sequence of formation of titanium nitrides by nitrogen implantation

Room‐temperature implantation was conducted for the thin titanium films by 80‐keV nitrogen ions. It was found that TiN began to appear at a dose around 2×1017 N/cm2, and the titanium film converted entirely into TiN after 1×1018 N/cm2 implantation. Surprisingly, Ti2N, which has a lower N/Ti ratio than TiN, was only detected at an even higher implantation dose, e.g., as high as 2×1018 N/cm2. This reverse sequence of titanium nitride formation was attributed to the structural compatibility between the matrix and new phase being formed. Viewed in this light, a shearing mechanism is proposed, which can explain the titanium nitride formation, and is also applicable to other metal nitrogen systems.