Toshiji Umezawa

Stoichiometry of Ta–N Film and Its Application for Diffusion Barrier in the Al3Ta/Ta–N/Si Contact System

In order to obtain a stable contact structure applicable to Si–LSI thin film technology, we have produced the contact structure of Al3Ta/Ta–N/Si by interposing the Ta–N film as a diffusion barrier between Al3Ta film and Si substrate. The contact structure was heat-treated at various temperatures in vacuum, and the behavior of mass transport across the interfaces of both Al3Ta/Ta–N and Ta–N/Si caused by the heating process was examined by Auger depth analysis. Also, on the basis of X-ray diffraction and XPS analysis, the barrier properties of the Ta–N film were examined with respect to the crystalline state and the chemical bonding state of the film. It is revealed that the thermal stability of this contact structure is closely related to the stoichiometry of the Ta–N film used as a diffusion barrier.

Preparation and Characterizations of Al3Ta Intermetallic Compound Films

The intermetallic compound film of Al3Ta was prepared by co-sputtering at a substrate temperature as low as 400degC. Effects of subsequent annealing in air on the grain growth and on the electrical properties were examined. It is revealed from the Auger electron spectroscopy analysis that the film surface is covered with a thin Al2O3 layer which protects the film from further oxidation. The films obtained are sufficiently applicable as a metallization material for large-scale integrated circuits.

Interaction of Al3Ta Intermetallic Compound Film with Si

The interaction of deposited Al3Ta intermetallic compound film with a silicon substrate is studied by Auger electron spectroscopy in order to examine the suitability of film for use instead of aluminum as a metallization material. Penetration of aluminum into silicon and formation of aluminum spikes are completely blocked by a thin interfacial layer consisting of Ta and Si formed at the interface between Al3Ta and silicon. It is revealed that Al3Ta film is a useful material as a high-quality metallization for silicon devices.