Evaluation and localization of oxygen in thin TiN layers obtained by RTLPCVD from TiCl4-NH3-H2

Oxygen is well known to play a significant role in the barrier behavior of titanium nitride layers for the IC metallization. TIN thin films are deposited by rapid thermal low pressure chemical vapor deposition from the TiCl4-NH3-H-2 gaseous phase onto silicon substrate. Oxygen contamination level lies in the range of 3.5-10% when the deposition temperature decreases from 800-500 degrees C. The aim of this paper is to localize oxygen in the layer by a variety of complementary analytical techniques: Rutherford backscattering spectrometry, nuclear reactive analysis, Auger electron spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction and scanning electron microscopy. These analyses show that O is diffused in the him from the surface, and for low temperature films, O is most present at the interface TiN/Si. With small O contents (<3%), this contamination is situated at grain boundaries, and for higher contents, O is diffused in the grains. For high temperatures, a columnar structure is observed, and for low temperatures, a granular structure is observed. The layers are covered by copper and work well as a diffusion barrier between copper and silicon. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.