CMP for Cu Interconnect with Advanced Barrier Materials

摘要

Co and Ru have been extensively investigated as candidate materials for advanced barrier applications for the 2X technology node and beyond. However, integration of these barrier materials brings new challenges to Chemical Mechanical Planarization (CMP) processes. Since Co and Ru have different electrochemical potentials relative to Cu, galvanic corrosion can occur at multiple stages of the CMP process, including Cu polishing, barrier polishing, and post CMP cleaning. In this paper, we discuss CMP technology for Cu interconnects with a Co seed enhancement liner (SEL) and Cu with a Ru barrier. Typical forms of galvanic corrosion for each type of barrier are also reviewed. To meet CMP performance requirements, specific polishing and cleaning processes for each CMP step were developed. The overall performance of CMP was evaluated using a variety of patterned wafers, and results are presented.