Ti-based Barrier for Cu Interconnect Applications

After being forgotten for a number of years, Ti has recently re-gained attention for use in Cu barrier applications. For advanced logic products utilizing porous ultra low-k (ULK) dielectric, the main motivation of using a Ti-based barrier is that compared with a Ta-based barrier, the Ti-based barrier is more compatible with porous ULK due to its better resistance to the moisture associated with porous ULK films [1]. For memory products, the main driving force for switching from Ta to Ti is lower cost. Ti offers significantly lower cost of consumables (COC) than Ta. Regardless of product types, there is also a general interest in Ti due to its potential for reliability improvement. In this paper we present an approach of Ti-based barrier that not only addresses the known integration issues associated with Ti, but also demonstrates significant reliability improvement over a Ta-based barrier.