Method of low temperature plasma enhanced chemical vapor deposition of TiN film over titanium for use in via level applications

A titanium/titanium nitride film stack can be formed with reduced amounts of impurity by depositing onto a substrate a film of titanium using plasma-enhanced chemical vapor deposition of titanium tetrachloride and hydrogen. This film is then subjected to a hydrogen/argon plasma which significantly reduces the chlorine content of the titanium film. The titanium film can then be subjected to an ammonia plasma which will form a thin layer of titanium nitride which is then coated with a thick layer of titanium nitride using plasma-enhanced chemical vapor deposition of titanium tetrachloride and ammonia. The hydrogen/argon anneal significantly reduces the chlorine content of the titanium film and thus the chlorine content at the titanium substrate interface, particularly when the substrate contains aluminum. This enhances the overall reliability of the formed product.