Self Aligned Barrier Approach: Overview on Process, Module Integration and Interconnect Performance Improvement Challenges

Self aligned barriers approaches are widely investigated because they lead to a strong improvement of the Cu/barrier interface adhesion generally considered as the limiting factor for the electromigration performance of Cu interconnects capped with dielectric barriers. In this paper, several ways to perform self aligned barrier integration, using either Cu line surface treatments or selective deposition process on top of Cu lines and their basic performance are detailed. Achieved electrical and reliability performance are discussed in terms of process, integration feasibility and related issues, and architecture (stand-alone or bi-layered stack) since the self aligned barriers can be introduced at different levels of complexity depending on the performance targets and the applications foreseen