Evaluation and localization of oxygen in thin TiN layers obtained by RTLPCVD from TiCl 4–NH 3–H 2

Abstract

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 TiCl 4–NH 3–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°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 film 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.