NOVEL PLASMA REMOVAL OF A TITANIUM NITRIDE FILM

A process has been developed for the highly selective removal of titanium nitride (TiN), an antireflective coating, used in a 1.0-mu-m titanium/aluminum/copper/silicon (TACS) minimum ground-rule dynamic random access memory wiring technology. This technique also eliminates a post-metal-etch surface residue generated during the etch process. This residual was thought to be organic, but has since been determined to be metallic in nature. We found that both the TiN and the metallic residual can be removed from the TACS surface by reversing the passivation-resist strip sequence. This is contrary to the industry-standard sequence of reactive ion etching metal etch. passivation, and resist strip. The elimination of the residual from the surface of the metal results in both post-metal-etch processing and product quality improvements.