Evaluation and localization of oxygen in thin TiN layers obtained by RTLPCVD from TiCl4-NH3-H-2

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 deposi ted by rapid thermal low pressure chemical vapor deposition from the TiCl4- NH3-H-2 gaseous phase onto silicon substrate. Oxygen contamination level li es in the range of 3.5-10% when the deposition temperature decreases from 8 00-500 degrees C. The aim of this paper is to localize oxygen in the layer by a variety of complementary analytical techniques: Rutherford backscatter ing spectrometry, nuclear reactive analysis, Auger electron spectroscopy, X -ray photoelectron spectroscopy, X-ray diffraction and scanning electron mi croscopy. These analyses show that O is diffused in the him from the surfac e, 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 boun daries, and for higher contents, O is diffused in the grains. For high temp eratures, a columnar structure is observed, and for low temperatures, a gra nular structure is observed. The layers are covered by copper and work well as a diffusion barrier between copper and silicon. (C) 1999 Published by E lsevier Science Ltd. All rights reserved.