The thermal stability of an &agr;‐Ti film in contact with a &dgr;‐TiN film in the structure of a TiN/Ti/TiN film stack on SiO2substrates was studied byinsitusheet resistance (Rs) measurement, Auger electron spectroscopy, glancing angle x‐ray diffractometry, cross‐sectional transmission electron microscopy, scanning electron microscopy, and atomic force microscopy. It was found that nitrogen dissolves from TiN into Ti between 405 and 474 °C and a significant reaction between Ti and TiN results in the formation of &egr;‐Ti2N in the temperature range of 505–548 °C. ©1996 American Institute of Physics.