In-situ study of Ti/TiN stability under nitrogen anneal

Abstract

The effectiveness of a TiN capping layer to prevent the conversion of α-titantium to titanium nitride when annealed in a nitrogen ambient has been studied over the temperature range 300-700°C using in-situ high temperature diffraction and transmission electron microscopy. Over the time range of interest (four hours), no evidence of Ti reaction was observed at 300°C. At 450°C, nitrogen was found to diffuse into the Ti to form a Ti(N) solid solution. Above 500°C the titanium is transformed to a second phase; however this reaction follows two different kinetic paths, depending on the annealing temperature. Below 600°C, the reaction proceeds in two stages, with the first stage consisting of Ti(N) formation, and the second stage consisting of the conversion of the Ti(N) with a transformation mechanism characteristic of short range diffusion (grain edge nucleation). Above 600°C, a simple linear transformation rate is observed. © 1999 Materials Research Society.